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Wyszukujesz frazę "reaction;" wg kryterium: Temat


Tytuł:
Decomposition Pathways for Aqueous Hydroxylammonium Nitrate Solutions: a DFT Study
Autorzy:
Izato, Y.
Koshi, M.
Miyake, A.
Powiązania:
https://bibliotekanauki.pl/articles/357968.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
hydroxylamine nitrate
reaction pathway
liquid-phase reaction
density functional theory
Opis:
Hydroxylammmonium nitrate (hydroxylamine nitrate, HAN) is one of the most promising candidates as a replacement for commonly used liquid mono-propellants such as hydrazine. The reaction pathways involved in the initial and the catalytic decomposition of HAN in aqueous solution were determined using quantum chemistry calculations incorporating solvent effects. Optimized structures were obtained for the reactants, products and transition states at the ωB97XD/6-311++G(d,p)/SCRF = (solvent = water) level of theory and the total electron energies of these structures were calculated at the CBS-QB3 level of theory. In the initial decomposition, the ion-neutral NH3OH+-HNO3 reaction, the neutral-neutral NH3O-HNO3 reaction and the HNO3 self-decomposition pathways were all found to have reasonable energy barriers, with values of 91.7 kJ/mol, 88.7 kJ/mol and 89.8 kJ/mol, respectively. The overall reaction resulting from any of these pathways can be written as: HAN → HONO + HNO + H2O. The ionic reaction is dominant during the initial decomposition of HAN in aqueous solution because NH3OH+ and NO3– are the major species in such solutions. We also developed six catalytic mechanisms and each of these schemes provided the same global reaction: NH2OH + HONO → N2O + 2H2O. The t-ONONO2 oxidizing scheme is the most plausible based on the energy barrier results.
Źródło:
Central European Journal of Energetic Materials; 2017, 14, 4; 888-916
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A meta-analysis of influence of yoga activities on reaction time as a component of skill related fitness
Autorzy:
Ghuntla, Tejas P.
Dholakiya, Jyoti R.
Powiązania:
https://bibliotekanauki.pl/articles/26917700.pdf
Data publikacji:
2023
Wydawca:
Akademia Tarnowska
Tematy:
yoga activities
auditory reaction time
visual reaction time
fitness
effect
Opis:
Introduction: Yoga practices are known to have beneficial effect on cognitive functions. Reaction is a purposeful voluntary response to external stimuli. Reaction time is a component of skill related fitness. Humans gives response to different external environmental stimuli with different speed. Majority of daily work is done in response to visual and auditory stimuli. Yoga practices may improve reaction time. Objectives: To study influence of yoga practices on auditory reaction time and visual reaction time. Methods: Researchers used the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) guidelines for reporting systematic reviews and meta-analysis. Researchers searched articles on PubMed, Google scholar and by manual search. Searched articles were screened for relevancy. By use of inclusion and exclusion criteria potential articles were selected. Results: Out of 287articles, finally 5 studies included in current meta-analysis. Yoga activities has effect on visual reaction time (VRT): SMD = 3.06, 95% CI = –0.66–6.78, P < 0.01 and auditory reaction time (ART): SMD = 2.86, 95% CI = –0.37–6.09. Conclusion: Yogic activities can provide beneficial effect on reaction time. Improved reaction time is important for reactive activity like sports. Yoga can be useful as a part of training in skill related work. There is wide scope for further studies to evaluate beneficial effects of yoga activities.
Źródło:
Health Promotion & Physical Activity; 2023, 24, 3; 50-55
2544-9117
Pojawia się w:
Health Promotion & Physical Activity
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detonation Reaction Characteristics for CL-20 and CL-20-based Aluminized Mixed Explosives
Autorzy:
Liu, D.
Chen, L.
Wang, C.
Wu, J.
Powiązania:
https://bibliotekanauki.pl/articles/358308.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
detonation reaction zone
aluminum reaction
interfacial particle velocity
interferometry
Opis:
The interfacial particle velocities for CL-20 and CL-20-based aluminized mixed explosives were measured by interferometry in order to analyze the aluminum reactions in the latter. The reaction characteristics were obtained, as well as a better understanding of the effects of aluminum powder on the detonation reaction zone length. Two functions were used to fit the particle velocity-time profiles, and their intersection was the corresponding Chapman-Jouget (CJ) point. From these profiles, the detonation reaction zone length and the aluminum reaction were then analyzed. CL-20-based explosives have a short reaction time (48 ns for a high CL-20 content), while the reaction time of CL-20/Al explosives increased with the aluminum content and particle size. Micron-scale aluminum particles barely reacted in the CL-20 detonation reaction zone, but instead reacted with the detonation products after the CJ point. This reduced the detonation pressure; however, the aluminum reaction can slow down the decrease in particle velocities. The start times of small-particle aluminum reactions were earlier than those of the larger particles. The 2-3-μm aluminum particles start to react within 1 μs after the CJ point, while the 200-nm particles may start to react in the reaction zone.
Źródło:
Central European Journal of Energetic Materials; 2017, 14, 3; 573-588
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kto się boi księcia Metternicha?
Autorzy:
Tarnawski, Eduard
Powiązania:
https://bibliotekanauki.pl/articles/630372.pdf
Data publikacji:
2013
Wydawca:
Szkoła Główna Handlowa w Warszawie
Tematy:
conservatism, reaction, liberalism
Opis:
Th e author proposes a test for the propensity of being a reactionary that he calls ”Metternich test”, although Robert Stewart Castlereagh (1769–1822) could also be called as an examiner. Undoubtedly only Russian tsars can be considered reactionary monarchs, starting from Nicholas I (1796–1855). To judge whether president Putin is a reactionary we need authority of Alexandr Solzhenitsyn (1918–2008). Although Henry Kissinger is called Metternich of 20th century, he is not suit for the function of examiner. Author elaborates on the faith Metternich had in love as a force that makes politics possible. A person that can’t understand the life of other people, cannot understand history. Aft er Nicholas I became tsar all Russian doctinaires, such as Sergey Uvarov (1786–1855), Konstantin Leontiev (1831–1891) and Konstantin Pobedonostsev 1827–1907), formulated principles of reaction. The paper ends with Wacław Nałkowski’s (1851–1911) critique of Henryk Sienkiewicz as a reactionary.
Źródło:
Kwartalnik Kolegium Ekonomiczno-Społecznego Studia i Prace; 2013, 4; 113-136
2082-0976
Pojawia się w:
Kwartalnik Kolegium Ekonomiczno-Społecznego Studia i Prace
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic recykling of complex catalysts immobilized on thiol-functionalized polymer supports
Autorzy:
Bączek, N
Strzelec, K.
Wąsikowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/779554.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
encapsulation
magnetic recycling
epoxy resin
supported catalysts
Heck reaction
hydrogenation reaction
Opis:
In this work, the application of the thiol-functionalized epoxy resin encapsulated on magnetic core as supports for palladium catalysts is reported. The study focuses on obtaining of heterogeneous catalysts which can be separated by magnetic field. Palladium complex catalyst [PdCl2(PhCN)2] has been heterogenized by anchoring to these supports via ligand exchange reaction. The characterization of polymeric supports and heterogenized palladium catalysts has involved research methods like time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning electron microscopy (SEM) and nitrogen BET surface area measurements. The activity and stability during long-term use of the investigated catalytic systems were tested in a Heck and hydrogenation reaction. The influence of the type of thiols used as epoxy hardeners and the morphology of the supports on the catalytic properties of epoxy-supported palladium catalysts was discussed.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 3; 65-68
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One-pot three component (LaCl3•7H2O) catalysed biginelli reaction for the synthesis of 1,2,3,4-tetrahydropyrimidine
Autorzy:
Murugesan, C.
Sihabudeen, M. Mohamed
Ahamed, A. Asrar
Powiązania:
https://bibliotekanauki.pl/articles/1190119.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
2
3
4-tetrahydropyrimidine; one pot synthesis
Multicomponent reaction; Biginelli reaction; 1
Opis:
A Series of tetrahydropyrimidine has been derived by LaCl3•7H2O catalysed one pot three component biginelli reaction. The compounds have synthesised from an aldehyde, ethyl acetoacetate and urea or thiourea in an ethanolic medium using a catalytic amount of (LaCl3•7H2O). This method provides quantitative yield and the catalysis can be easily recovered from the reaction medium and be re-used.
Źródło:
World Scientific News; 2016, 35; 87-99
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza kinetyki reakcji złożonych na przykładzie rozkładu azotanu amonu
Analysis of the kinetics of complex reactions on the example of the decomposition of ammonium nitrate
Autorzy:
Popławski, D.
Huculak-Mączka, M.
Hoffmann, K.
Hoffmann, J.
Powiązania:
https://bibliotekanauki.pl/articles/125902.pdf
Data publikacji:
2018
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
kinetyka rozkładu
reakcja złożona
azotan amonu
reaction kinetics
complex reaction
ammonium nitrate
Opis:
W pracy przedstawiono sposób wyznaczenia parametrów kinetycznych złożonej reakcji rozkładu azotanu amonu. W obliczeniach wykorzystano dane pochodzące z pomiarów przeprowadzonych z zastosowaniem skaningowej kalorymetrii różnicowej sprzężonej z termograwimetrią i spektrometrią mas (DSC-TG-MS). Badane próbki ogrzewano z trzema różnymi szybkościami: 3, 5 i 10 K/min. Parametry kinetyczne reakcji rozkładu wyznaczono z zastosowaniem metody dopasowywania modelu, wykorzystując regresję nieliniową. Uzyskane wyniki zdają się potwierdzać współistnienie dwóch konkurujących ze sobą procesów: endotermicznej dysocjacji i odparowania azotanu amonu oraz jego egzotermicznego rozkładu.
The paper presents a method of determining the kinetic parameters of complex reaction of ammonium nitrate decomposition. The data from measurements carried out with the use of differential scanning calorimetry coupled with thermogravimetry and mass spectrometry (DSC-TG-MS) were used in the calculations. The test samples were heated with three different rates: 3, 5 and 10 K/min. Kinetic parameters of the decomposition reaction were determined by model fitting method using nonlinear regression. The obtained results seem to confirm the existence of two competing processes: the endothermic dissociation and evaporation of ammonium nitrate and its exothermic decomposition.
Źródło:
Proceedings of ECOpole; 2018, 12, 2; 561-569
1898-617X
2084-4557
Pojawia się w:
Proceedings of ECOpole
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of a 9-week training intervention on the reaction time of fencers aged 15 to 18 years
Autorzy:
Balkó, Štefan
Rous, Miroslav
Balkó, Iva
Hnízdil, Jan
Borysiuk, Zbigniew
Powiązania:
https://bibliotekanauki.pl/articles/1031761.pdf
Data publikacji:
2017
Wydawca:
PPHU Projack Jacek Wąsik
Tematy:
simple reaction time
choice reaction time
visual stimulus
fencing
training process
Opis:
The purpose of the present study was to determine if it is possible to affect the level of simple (SRT) and choice (CRT) reaction time of fencers with a specific 9-week (in total 350 minutes) training intervention. The research sample consisted of 19 healthy fencers (12 boys, 16±1.1 years and 7 girls, 16.4±0.9 years). Five of the tested subjects were selected as the control group that did not participate in the reaction time training. The training of the experimental group was conducted on an Electronic Fencing Target (EFT-1). All tested individuals completed an entrance and exit reaction time test on the Fitrosword device, which consisted of hitting the target with an epée from the guard position after lighting of an LED light (green, red, yellow) by using various motor responses of the armed arm. No difference in reaction time (SRT, CRT) was found between the experimental and control groups for the entrance test. A significant difference between groups was found for results of the CRT (p = 0.116, d = 0.722) after the 9-week training. A significant difference in CRT was also found between the entrance and the exit tests in the experimental group (p = 0.013, r = 0.469). This difference was not significant in the case of the control group (p = 0.345, r = 0.298). Based on these results, we can assume a positive impact of specific reaction time training on response speed. We can use these results in the training process to improve reaction time, which is an important component of overall sports performance in many combat disciplines, such as karate, boxing, taekwondo, judo, and fencing, as well as motorsports, ball games, etc.
Źródło:
Physical Activity Review; 2017, 5; 146-154
2300-5076
Pojawia się w:
Physical Activity Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Classical Approach to Dynamics of Parabolic Competitive Systems
Autorzy:
Pietruk, Małgorzata
Przeradzki, Bogdan
Powiązania:
https://bibliotekanauki.pl/articles/44444333.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
Reaction-diffusion system
competition.
Opis:
We study the reaction-diffusion system, its stationary solutions, the behavior of the system near them and discuss similarities and differences for different boundary conditions.
Źródło:
Acta Universitatis Lodziensis. Folia Mathematica; 2010, 17; 23-38
2450-7652
Pojawia się w:
Acta Universitatis Lodziensis. Folia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sprzężone nitroalkeny jako komponenty nieuzgodnionych reakcji Dielsa-Aldera – najnowsze doniesienia
Conjugated nitroalkenes as components of nonconcerted Diels-Alder reactions – recent studies
Autorzy:
Jasińska, E.
Dresler, E.
Łapczuk-Krygier, A.
Kącka, A.
Nowakowska-Bogdan, E.
Jasiński, R.
Powiązania:
https://bibliotekanauki.pl/articles/142568.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
Tematy:
Nitroalkeny
reakcja Dielsa-Aldera
cykloaddycja
mechanizm
Nitroalkenes
Diels-Alder reaction
cycloaddition reaction
mechanism
Opis:
W pracy przedyskutowano najnowsze doniesienia dotyczące możliwego, nieuzgodnionego przebiegu reakcji Dielsa-Aldera z udziałem sprzężonych nitroalkenów.
In the publication the recent progres concerning non-concerted Diels-Alder reactions with conjugated nitroalkenes has been discussed.
Źródło:
Chemik; 2015, 69, 7; 395-400
0009-2886
Pojawia się w:
Chemik
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ability to maintain attention during visuomotor task performance in handball players and non-athletes
Autorzy:
Zwierko, Teresa
Florkiewicz, Beata
Fogtman, Sławomir
Kszak-Krzyżanowska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1054843.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
sustained attention
handball
reaction time
Opis:
One of the important aspects of attentional processes in sport performance is sustained attention during task execution. The objective of this study was to analyze the ability to maintain attention during a serial reaction time task performance in expert handball players (n = 12) and non-athletes (n = 12). Participants p erform a FitLight TrainerTM (Fitlight Sports Corp., Canada) test protocol configured by the PDA controller which consisted of 10 series of simple motor reaction task to visual stimuli appearing on 8 wireless light discs. Each of the 10 series included 22 reactions. Ability to maintain attention was determined by analyzing the variability in results during testing, e.g. the total time of test execution and the average reaction time to visual stimulus in each subsequent series. The main finding in our study was that Non-athletes in comparison to Athletes had: (1) longer total time of test execution; (2) longer reaction time; (3) and higher variability in results during task performance. The results indicate a higher level of ability to maintain attention in handball players.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2014, 7, 3; 99-106
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of in vitro biodegradation on the properties of BNC in the aspect of its use as a material for the cardiac implants production
Autorzy:
Dederko, P.
Walczuk, M.
Malinowska-Pańczyk, E.
Staroszczyk, H.
Kołodziejska, I.
Powiązania:
https://bibliotekanauki.pl/articles/284976.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
BNC reaction
cardiac implants
biodegradation
Źródło:
Engineering of Biomaterials; 2016, 19, 138; 19
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of diamond powder in the ionization process
Autorzy:
Brzecka, P.
Janaszczyk, A.
Chuchracki, M.
Mitura, K.
Powiązania:
https://bibliotekanauki.pl/articles/284028.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
diamond powder
ionization
allergic reaction
Źródło:
Engineering of Biomaterials; 2017, 20, no. 143 spec. iss.; 86
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occurrence of total and sulphate sulphur in arable soils of Poznan region and their reaction
Autorzy:
Jakubus, M.
Czekala, J.
Powiązania:
https://bibliotekanauki.pl/articles/799102.pdf
Data publikacji:
1998
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
occurrence
sulphate sulphur
arable soil
Poznan region
soil reaction
chemical reaction
natural environment
Opis:
In this work are presented the results of investigations related to total and sulphate sulphur contents in humus horizon of arable soils of 15 Poznań province and their soil reaction. On the basis of obtained results it was found that analysed soils of municipalities contained from 9.0 to 182.0 mg total S/100 g of soil. The data follows that the content of total sulphur was differentiated not only between soils of researched municipalities but also in limit of each other. The quantitative differences of sulphate sulphur, which one content range from 0.03 to 19.7 mg S-SO₄/100g of soil corresponded with the differentiation of total sulphur. Soil reaction of the researched soils like sulphur was differentiated and ranged from pH 3.8 to 7.9.
Źródło:
Zeszyty Problemowe Postępów Nauk Rolniczych; 1998, 456
0084-5477
Pojawia się w:
Zeszyty Problemowe Postępów Nauk Rolniczych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of in vitro biodegradation on the structure of BNC in the aspect of its use as a material for the cardiac implants production
Autorzy:
Dederko, P.
Walczuk, M.
Staroszczyk, H.
Malinowska-Pańczyk, E.
Kołodziejska, I.
Powiązania:
https://bibliotekanauki.pl/articles/284696.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
BNC reaction
cardiac implants
biodegradation
Źródło:
Engineering of Biomaterials; 2016, 19, 138; 20
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of diphenylphosphinic acid esters
Autorzy:
Korzeniowska, Ewelina
Powiązania:
https://bibliotekanauki.pl/articles/763978.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
diphenylphosphinic acid esters, substitution reaction
Opis:
The development of new methods for the synthesis of organophosphorus compounds is still an important part of organic chemistry due to the high demand for these compounds in organic synthesis as well as in asymmetric catalysis. Most of the methods for the synthesis of these compounds include the reactivity of the phosphorus atom, which depending on the structure might exhibit both electrophilic and nucleophilic properties. Herein, I will present the results concerning synthesis of diphenylphosphinic acid esters.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia; 2017, 72, 1
2083-358X
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Toward a European Network of Positron Laboratories
Autorzy:
Karwasz, G. P.
Brusa, R. S.
Egger, W.
Ogorodnikova, O. V.
Powiązania:
https://bibliotekanauki.pl/articles/146548.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
positron beams
material science
thermonuclear reaction
Opis:
Some applications of controlled-energy positron beams in material studies are discussed. In porous organic polysilicates, measurements of 3γ annihilation by Doppler broadening (DB) method at the Trento University allowed to trace pore closing and filling by water vapor. In silicon coimplanted by He+ and H+, DB data combined with positron lifetime measurements at the München pulsed positron beam allowed to explain Si blistering. Presently measured samples of W for applications in thermonuclear reactors, irradiated by W+ and electrons, show vast changes of positron lifetimes, indicating complex dynamics of defects.
Źródło:
Nukleonika; 2015, 60, No. 4, part 1; 733-739
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kontrowersyjne produkty reakcji Maillarda w żywności
Controversial Maillard reaction products in food
Autorzy:
Kruszewski, B.
Obiedziński, M.
Powiązania:
https://bibliotekanauki.pl/articles/270510.pdf
Data publikacji:
2011
Wydawca:
Centralny Ośrodek Badawczo-Rozwojowy Aparatury Badawczej i Dydaktycznej, COBRABiD
Tematy:
reakcja Maillarda
żywność
Maillard reaction
food
Opis:
Reakcja Maillarda to szereg następujących po sobie reakcji pomiędzy cukrami redukującymi a aminokwasami, peptydami i białkami zawierającymi wolną grupę aminową, które prowadzą do utworzenia licznej grupy związków chemicznych. Wpływ na reakcję ma przede wszystkim temperatura ale także czas reakcji, ciśnienie, czy pH środowiska. Grupa nowo powstałych związków nadaje głównie barwę, smak i zapach produktowi spożywczemu. Dane literaturowe wskazują na ich liczne pozytywne i negatywne właściwości. Część substancji uznana została za kancerogenne i mutagenne. Natomiast inne wykazują wysoki potencjał przeciwutleniający, antymutagenny i antyrakowy.
The Maillard reaction is number of successive reactions between reducing sugars and amino acids, peptides and proteins containing a free amino group, which lead to the creation of large group of chemical compounds. Influence on the reaction has mostly temperature but also the reaction time, pressure, or matrix pH. Group of new formed compounds mainly gives color, taste and smell of the food product. Literature data indicate many of their positive and negative properties. Some substances has been recognized as carcinogenic and mutagenic. The second part has high antioxidant, anti-cancer and anti-mutagenic potential.
Źródło:
Aparatura Badawcza i Dydaktyczna; 2011, 16, 4; 37-41
2392-1765
Pojawia się w:
Aparatura Badawcza i Dydaktyczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Serum metallothionein in newly diagnosed patients with childhood solid tumours
Autorzy:
Krizkova, Sona
Masarik, Michal
Majzlik, Petr
Kukacka, Jiri
Kruseova, Jarmila
Adam, Vojtech
Prusa, Richard
Eckschlager, Tomas
Stiborova, Marie
Kizek, Rene
Powiązania:
https://bibliotekanauki.pl/articles/1040324.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
cancer
Brdicka reaction
serum
marker
metallothionein
Opis:
Tumour markers are substances produced by malignant cells or by the organism as a response to cancer development. Determination of their levels can, therefore, be used to monitor the risk, presence and prognosis of a cancer disease or to monitor the therapeutic response or early detection of residual disease. Time-consuming imaging methods, examination of cerebrospinal fluid or tumour tissue and assays for hormones and tumour markers have been used for cancer diagnosis. However, no specific marker for diagnosis of childhood solid tumours has been discovered yet. In this study, metallothionein (MT) was evaluated as a prospective marker for such diseases. Serum metallothionein levels of patients with childhood solid tumours were determined using differential pulse voltammetry - Brdicka reaction. A more than 5-fold increase in the amount of metallothionein was found in sera of patients suffering from cancer disease, compared with those in sera of healthy donors. The average metallothionein level in the sera of healthy volunteers was 0.5 ± 0.2 μmol · dm-3 and was significantly different (p<0.05, determined using the Schefe test) from the average MT level found in serum samples of patients suffering from childhood solid tumours (3.4 ± 0.8 μmol · dm-3). Results found in this work indicate that the MT level in blood serum can be considered as a promising marker for diagnostics, prognosis and estimation of therapy efficiency of childhood tumours.
Źródło:
Acta Biochimica Polonica; 2010, 57, 4; 561-566
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Differentiation of Visual Sensorimotor Processes in the Representatives of Various Sport Disciplines
Autorzy:
Lesiakowski, Piotr
Krzepota, Justyna
Zwierko, Teresa
Powiązania:
https://bibliotekanauki.pl/articles/1055208.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
reaction time
selective attention
sport training
Opis:
Sport activities usually require a high efficiency of visual information processing. Therefore, it seems justified to determine the efficiency of visual sensorimotor processes in sports requiring a variety of perception competencies. The aim of this study was to assess the differentiation of sensorimotor processes in terms of simple and choice reaction time, and visual stimulus discrimination in various athletes and untrained persons. The study involved 119 men, of which 95 were athletes: football players (n = 24), volleyball players (n = 22), boxers (n = 26), and rowers (n = 23). The efficiency of sensorimotor processes was evaluated with the Vienna Test System (Schuhfried, Austria). The evaluations included simple reaction time (SRT), choice reaction time (CRT), and visual stimulus discrimination. Analysis of the results showed that volleyball and football players had shorter (p < 0.01) reaction times compared to non-athletes and representatives of the other sports. We found significant differences (p < 0.01) between athletes and non-athletes in visual stimulus discrimination. In addition, boxers showed fewer correct reactions than volleyball players, and shorter times of stimulus detection than in volleyball and soccer players.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2017, 19, 3; 43-53
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptation of PCR technique for quantitative estimation of genetic material from different regions of chromosome 21 in cases of trisomy 21.
Autorzy:
Nowacka, Joanna
Helszer, Zofia
Walter, Zofia
Płucienniczak, Andrzej
Kałużewski, Bogdan
Powiązania:
https://bibliotekanauki.pl/articles/1041513.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
quantitative polymerase chain reaction
trisomy 21
Opis:
Pre- and postnatal diagnosis of chromosomal aberrations is generally based on conventional cytogenetic analysis. In this paper, we have devised a quantitative polymerase chain reaction (Q-PCR) method to determine gene dose effects and applied it in cases of regular trisomy 21 as a model. The method is based on quantitative assessment of PCR products after using primers amplifying DNA fragments located in the pericentromeric, heterochromatic, euchromatic and telomeric regions of chromosome 21. A gene dose effect on the amount of PCR product in cases of trisomy 21 was confirmed. Moreover, a correlation between the amount of the PCR product of the examined sequences and their location in the chromosome was observed. The obtained results suggest that the Q-PCR technique can be applied in the diagnosis of aneuploidies.
Źródło:
Acta Biochimica Polonica; 2004, 51, 4; 995-1001
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetics of in In vitro conversion of creatine to creatinine
Kinetyka konwersji kreatyny do kreatyniny In vitro
Autorzy:
Witkowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1398589.pdf
Data publikacji:
1985
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
creatine
creatinine
pH
kinetics of reaction
Opis:
The conversion of creatine to creatinine was studied at 60°C for pH from 1.2 to 7.0. The results showed that the reaction follow a first order rate. The rate constant calculated by use a simple regression technique achieved its maximal value 6.4X 10⁻² per hour at pH 3.4. The relationships between the rate constant and pH were described empirically by means of two parabolic equations, for pH range 1.2 to 3.4: k₁ = -1.92 X 10⁻² + 1.71 X 10⁻²pH + 2.25 X 10⁻³pH², and for pH range from 3.4 to 7.0 : k₂ = 3.07 X 10⁻¹ - 9.95 X 10⁻²pH+ 8.16 X 10⁻³pH².
Reakcję przemiany kreatyny do kreatyniny prowadzono w roztworach przygotowanych z czystego odczynnika kreatyny, techniką ampuł. Co określony czas wyjmowano po 1 próbie, schładzano, kontrolowano pH i oznaczano produkt reakcji, kreatyninę, metodą pikrynianową. Badania wstępne prowadzono w 100°C, w 0,1 mM HCl, przy początkowym stężeniu kreatyny 10 mM, przy pH 1,6. Wykreślenie zależności logarytmu aktualnego stężenia kreatyny [A] do czasu trwania reakcji (t), dawało linię prostą (rys. 1), badana reakcja jest więc pierwszego rzędu. Badania wpływu pH, (w zakresie od 1,2 do 7,0), na szybkość przemiany kreatyny do kreatyniny prowadzono w temperaturze 60°C, przy początkowym stężeniu kreatyny 5 lub 10 mM, w buforach glicynowym, ftalanowym, fosforanowym, z dodatkiem HCl, NaOH albo NaCI. Dane doświadczalne, wyniki oznaczeń kreatyniny w czasie reakcji oraz stałe szybkości reakcji wyliczone prostą techniką regresji, przedstawiono w tabeli 1. Wysokie współczynniki korelacji między stężeniem kreatyniny i czasem trwania reakcji (r ≤ 0,97) potwierdzają, że jest ona pierwszego rzędu. W badanym przedziale pH, graficzne przedstawienie zależności stałej szybkości reakcji lub jej logarytmu - od pH dawały krzywą Gaussa. Najwyższą szybkość reakcji obserwowano przy pH 3,4. Uzyskaną zależność opisano empirycznie za pomocą dwóch równań paraboli, dla zakresu pH od 1,2 do 3,4 i dla zakresu pH od 3,4 do 7,0. Wyliczone równania przedstawiono w tabeli 2. a ich ilustrację, w porównaniu z wynikami doświadczeń, na rys. 2. Dotychczasowe poglądy, według których szybkość badanej reakcji jest najwyższa przy pH 2, mogły być skutkiem braku kontroli pH w czasie i po reakcji. Prowadzenie reakcji w 100°C, zwłaszcza przy wysokim początkowym stężeniu kreatyny w buforach o niskiej pojemności powodowało wzrost pH, a więc i zmiany stałej szybkości reakcji w czasie jej trwania. Prowadzenie reakcji w 40°C przedłużało czas jej trwania do kilku dni Prowadzenie reakcji w temp. 60°C pozwoliło na uzyskanie dużego stopnia przereagowania (dochodzącego do 80% przy pH około 3,4) w czasie 1 doby bez zmian pH środowiska przy zastosowanych buforach.
Źródło:
Acta Alimentaria Polonica; 1985, 11, 2; 263-269
0137-1495
Pojawia się w:
Acta Alimentaria Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the acrosome reaction on the efficiency of sperm-mediated DNA transfer
Autorzy:
Mu, Y.
Jiang, C.
Jiao, M.
Zhao, Y.
Lv, J.
Liu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2087625.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
spermatoza
SMGT
acrosome reaction
exogenous DNA
Źródło:
Polish Journal of Veterinary Sciences; 2018, 21, 4; 755-762
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metody syntezy pochodnych organicznych zawierających wiązanie potrójne węgiel-węgiel
Methods for the synthesis of organic derivatives containing the triple bond carbon-carbon
Autorzy:
Bylińska, I.
Guzow, K.
Powiązania:
https://bibliotekanauki.pl/articles/171636.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie potrójne
acetylen
synteza
homosprzęganie
heterosprzęganie
reakcja Glasera
reakcja Haya
reakcja Cadiota-Chodkiewicza
reakcja Sonogashiry-Hagihary
triple bond
acetylene
synthesis
homocoupling
heterocoupling
Glaser reaction
Hay reaction
Cadiot-Chodkiewicz reaction
Sonogashira-Hagihara reaction
Opis:
Compounds containing triple bonds are lately in the centre of interest of many research groups. This is mainly connected with their usefulness as substrates to obtain complex compounds with various applications in different areas of science, industry and medicine [1–5]. Because of that many researchers are interested in methods of synthesis of such compounds. As the demand for derivatives with triple bonds is quite big and the one universal method of synthesis does not exist, the new ones are developed or these already known are improved. To enable choosing the best method for synthesis of acetylene derivatives, this review is presented. The oldest methods based on elimination reaction are mentioned [6–9], whereas those enabling incorporation of acetylene unit into more complicated compounds are described more thoroughly [10–92]. The latter methods based on homo- or heterocoupling lead to symmetrical [10–25] and unsymmetrical acetylene and bisacetylene derivatives [26–92]. The most popular reactions such as Glaser reaction (Scheme 1) [10–12], Cadiot-Chodkiewicz reaction (Schemes 11 and 12) [26–49], Hay reaction (Scheme 13) [13, 14] as well as Sonogashira-Hagihara reaction [50–69] and their modifications (Tab. 3) [57] are described. Moreover, the influence of main parameters such as type of substrate used, ratio of reagents, catalyst, base, solvent, reaction time and temperature on the reaction yield is presented (Tabs 1–4) [14, 18, 23, 25, 50–58, 69–78].
Źródło:
Wiadomości Chemiczne; 2012, 66, 9-10; 935-961
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nitrogen-doped pyrene as a catalyst for fuel cells
Autorzy:
Chudoba, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1179638.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
DFT
fuel cells
oxygen reduction reaction
Opis:
Density functional theory (DFT) was applied to study nitrogen-doped pyrene as an oxygen reduction reaction (ORR) cathode catalyst for fuel cells. Transition states and energy barriers were calculated to predict the catalytic properties of this substance.
Źródło:
World Scientific News; 2017, 72; 61-68
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal of oxidable contaminations contained in submarine atmosphere
Autorzy:
Kłos, R.
Powiązania:
https://bibliotekanauki.pl/articles/259834.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
breathing atmosphere contaminations
submarine
catalytic reaction
Opis:
To remove flammable contaminations from submarine atmosphere, devices for their oxidation and chemical absorption of products resulting from the chemical reaction1, can be applied. In this paper a catalytic system designed for hydrogen and carbon monoxide oxidation and its tests are presented.
Źródło:
Polish Maritime Research; 2008, 3; 67-69
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
How to search herbicide stress in plant system at molecular level?
Autorzy:
Korbin, Małgorzata
Adamczewski, Kazimierz
Twardowski, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/703392.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
herbicide
corn
plant reaction
molecular analysis
Opis:
Application of herbicides is connected with stress in plant system. Molecular signals of stress are of significant value. How to find them?
Źródło:
Nauka; 2009, 2
1231-8515
Pojawia się w:
Nauka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Investigation on the Crucible Discharge of Steel and Slag During the Aluminothermic Welding Process
Autorzy:
Weiss, S.
Riehl, I.
Hantusch, J.
Gross, U.
Powiązania:
https://bibliotekanauki.pl/articles/356989.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aluminothermic reaction
thermites
SHS
VOF
OpenFOAM
Opis:
The aluminothermic reaction is a type of self-propagating high-temperature synthesis to produce high quality metals and metal oxides en route. The main use of the aluminothermic reaction is in the field of railway welding. The multiphase flow of steel, slag and air in differently shaped crucibles has been numerically investigated in this work with the volume-of-fluid method. The simulations were carried out with the multiphase solver of the open source toolbox OpenFOAM. To validate the numerical results of the three-dimensional simulations, an experiment was carried out to investigate the discharge of a water-oil system from the crucible. A comparison to a numerical 3D simulation showed reasonable accurate results. It can be said that the solver is capable of predicting the point of the oil penetration of the water phase in the experiment.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 1; 173-180
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and characterization of fully substituted pyrimidines by using ketene dithioacetal as potent antimicrobial agent
Autorzy:
Khunt, H. R.
Pipaliya, P. P.
Ghelani, S. M.
Babariya, J. S.
Naliapara, Y. T.
Powiązania:
https://bibliotekanauki.pl/articles/412064.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
ketene dithioacetal
pyrimidines
guanidine
biginelli reaction
Opis:
Various ketene dithioacetals of acetoacetanilides were reacted with guanidine nitrate in the presence of base to produce the 2-amino-4-isopropyl-6-alkoxy-N-arylpyrimidine-5-carboxamide derivatives with good yields. All the synthesized compounds were characterized by mass, NMR and IR and also evaluated for antimicrobial activity against five different bacterial and fungal strains. The compounds 4i, 4k and 4l has found comparatively good active against all the bacterial strains.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 5; 134-141
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Green synthesis of pyrimidine derivative
Autorzy:
Sonawane, R. P.
Powiązania:
https://bibliotekanauki.pl/articles/412470.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
dihydropyrimidine derivatives
Biginelli reaction
Grindstone chemistry
Opis:
The majority of the drugs on the market today are entirely chemically synthesized in the laboratory. Several scientists had synthesized dihydropyrimidine (DHPMs) derivatives showing a wide spectrum of biological actions as antibacterials, antivirals as well as antitumor agents. This activity is principally due to presence of steriogenic carbon C4 in their structure. The current investigation is study and synthesis of dihydropyrimidinones efficiently and in high yields under mild, solvent free and eco-friendly conditions by using “Grindstone Chemistry Technique” catalyzed by CuCl2•2H2O and Conc. HCl. The obtained products have been identified by comparison with spectral data & their melting points. The synthesis of DHPMs derivative involves a multicomponent reaction (aldehyde derivative, urea /thiourea and 1,3-dicarbonyl compounds) in presence of HCl / NH4Cl as a catalyst. 3,4-dihydropyrimidin-2-(1H)-ones was synthesized and characterized using IR. The melting points was obtained 203 °C.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 2; 64-68
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Study of Chemical Synthesis of Pyrimidine Derivatives by Using Grindstone Chemistry Technique and Conventional Metod
Autorzy:
Sonawane, R. P.
Powiązania:
https://bibliotekanauki.pl/articles/412505.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
dihydropyrimidine derivatives
Biginelli reaction
Grindstone chemistry
Opis:
The majority of the drugs on the market today are entirely chemically synthesized in the laboratory. Several scientists had synthesized dihydropyrimidine (DHPMs) derivatives showing a wide spectrum of biological actions as antibacterials, antivirals as well as antitumor agents. This activity is principally due to presence of steriogenic carbon C4 in their structure. The current investigation is comparative study of chemically synthesis of two DHPMs derivatives by Biginelli Reaction using conventional method and grindstone chemistry technique. The synthesis of DHPMs derivative involves a multicomponent reaction (aldehyde derivative, urea /thiourea and 1,3-dicarbonyl compounds) in presence of HCl / NH4Cl as a catalyst. Two derivative viz. 3,4-dihydropyrimidin-2-(1H)-ones and 3,4-dihydropyrimidin-2-(1H)-thiones were synthesized and characterized using IR. The melting points were obtained are 208 °C and 210 °C respectively. “Grindstone Chemistry Technique” catalyzed by CuCl2•2H2O and Conc. HCl. gave more yield, solvent free and ecofriendly. The obtained products have been identified by comparison with spectral data & their melting points. This study will help to develop easy protocol for the synthesis of many more DHPMs derivative with high field.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 14, 1; 22-27
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of ultrasonic pretreatment on the flotation behavior of galena with and without the presence of pyrite
Autorzy:
Lu, Dongfang
Chen, Lanlan
Ma, Yongyi
Zheng, Xiayu
Wang, Yuhua
Powiązania:
https://bibliotekanauki.pl/articles/1449431.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
galena
ultrasonic pretreatment
flotation
electrochemical reaction
Opis:
Utilizing the ultrasonic pretreatment, flotation tests, ICP-OES, and XPS analysis, the effect of the different ultrasonic pretreatment methods on the flotation behavior of galena were investigated. The flotation recovery of galena was improved for pretreated single galena sample, which is mainly attributed to the efficient removal of the oxidized components and contaminants on the surface of galena by the acoustic cavitation. However, the flotation recovery of galena was decreased when pretreated mixture sample of galena and pyrite was used. Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) and X-ray photoelectron spectroscopy (XPS) results reveal that ultrasonic pretreatment facilitates the conversion of $PbS$ to $Pb(OH)_2$ and $PbSO_4$. Besides, the flotation recovery of galena was affected to varying degrees when the galena was mixed with the pyrite of the different particle sizes in the ultrasonic pretreatment process. The reason is that the change in the surface area ratio of these two minerals affects the electrochemical reaction rate between galena and pyrite.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 4; 611-624
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical reaction algorithm for type-2 fuzzy control optimization in mobile robots
Autorzy:
de la O, D.
Castillo, O.
Soria, J.
Powiązania:
https://bibliotekanauki.pl/articles/384488.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
Chemical Reaction Algorithm
control
fuzzy logic
robotics
Opis:
In this work the optimization process of the tracking and reactive controllers for a mobile robot are presented. The Chemical Reaction Algorithm (CRA) is used to find the optimal parameter values of the membership functions and rules for the reactive and tracking controllers. In this case, we are using five membership functions in each variable of the fuzzy controllers. The main goal of the reactive controller is aimed at providing the robot with the ability to avoid obstacles in its environment. The tests are performed on a benchmark maze problem, in which the goal is not necessarily to leave the maze, but rather that the robot avoids obstacles, in this case the walls, and penalizing for unwanted trajectories, such as cycles. The tracking controller’s goal is for the robot to keep into to a certain path, this in order that the robot can learn to react to unknown environments. The optimization algorithm that was used is based on an abstraction of chemical reactions. To perform the simulation we use the “SimRobot” toolbox, the results of the tests are presented in a detailed fashion, and at the end we are presenting a comparison of results among the CRA, PSO and GA methods.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2018, 12, 3; 10-19
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mild Method to Synthesize TATB by Amination of 1,3,5-Trialkoxy-2,4,6-Trinitrobenzene under Phase Transfer Catalysis Conditions
Autorzy:
Chang, T.
Li, B.
Chen, L.
Ge, L.
Lu, M.
Powiązania:
https://bibliotekanauki.pl/articles/358103.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
TATB
phase transfer catalysis
atmospheric amination reaction
Opis:
Nucleophilic amination, as a vital step in the synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using 1,3,5-trialkoxy-2,4,6-trinitrobenzene (TORTNB) and aqueous ammonia as the starting materials and catalyzed by phase transfer catalysis (PTCs) under mild conditions is described. Various phase transfer catalysts, such as crown ethers, tertiary amines, quaternary ammonium salts, poly ethers and cyclodextrin, and various experimental parameters, such as no. of equivalents of PTC, mole ratio of ammonium hydroxide to the starting material, reaction time, reaction temperature and cycle times of the organic phase were investigated. The crown ethers, especially 18-crown-6, show good catalytic activity and re-usability for the amination of 1,3,5-triethoxy-2,4,6-trinitrobenzene giving a yield of 96.52%. This makes for a safe process and suitable for scale-up, because the reactions are carried out under atmospheric conditions. The material synthesised by the new system was characterized by DSC, SEM and LPS.
Źródło:
Central European Journal of Energetic Materials; 2017, 14, 1; 47-59
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defining Duration of Driver Reaction Time Components Using the NeuroCom Complex
Autorzy:
Zhuk, M.
Kovalyshyn, V.
Tcir, R.
Powiązania:
https://bibliotekanauki.pl/articles/411357.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
driver reaction time
latent period
functional state
Opis:
The research defines components of driver reaction time under different conditions. The duration of a latent period and time of respective response to a stimulus are determined. It is traced how driver reaction time depends on the complexity of the situation the driver was exposed to. With the help of the NeuroCom complex, computer program and processing of video recordings, the main components of driver reaction time were defined to be information in-flow to the cerebral cortex, detection and recognition of a stimulus, making a right decision and respective reaction. The obtained results can be used for determining dynamic gauge and braking distance of a vehicle, which, in its turn, influences the road safety.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2015, 4, 2; 39-44
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of muscle soreness on the speed of performing a motor reaction speed task in football goalkeepers during a training camp
Autorzy:
Muracki, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1030952.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
DOMS
goalkeeper
muscle soreness
pain
reaction
speed
Opis:
Aim: To investigate the influence of muscle soreness on the speed of performing a motor reaction speed task in football goalkeepers. Methods: Twenty-four young healthy football goalkeepers, aged 1618 years old (average 16.7 ±0.67 year), with an average body height of 175.6 ±5.4 cm and body weight of 65 ±5 kg, participated in a study conducted during a 6-day training camp. The first day, referred to as day 0, was intended for initial tests and the following 5 days, referred to as days 15, consisted of training. On day 0, before the training period, anthropometric parameters such as weight and height were measured, subjects were questioned to determine the rate of perceived exertion (RPE) and perceived psychophysical readiness (PPR), a speed test with motor reaction choice (ST) was performed using a Smart Speed System and areas with muscle soreness (MS) were recorded by means of a computer tablet with the Navigate Pain application. The goalkeepers participated in two training sessions on each of the following 5 days. Before each training session, the same speed test was performed. Lap times for 5 m and 15 m were recorded. After the second training session each day, the participants drew digital pain maps using a computer tablet, marking separate areas of the body where they felt muscle soreness. These data were consolidated and the total area was analyzed to investigate if, throughout the training, there were any changes to the size of the area that was indicated as having MS. A categorization of body areas was also made to determine areas where muscle soreness was most frequently indicated. Each training session was monitored with heart rate (HR) registration and each goalkeeper determined his fatigue (RPE) and readiness to exercise (PPR) on a 110-point scale. Results: Twenty-three out of twenty-four (98.5%) goalkeepers indicated that they had MS during the study. Day 2 showed the highest incidence rate with 21 participants indicating that they felt MS. The biggest area of MS was also indicated on day 2, yet statistical analysis did not show significant differences in the area of MS between the training days. MS was most often indicated in the upper leg, i.e. the thighs. The average time of the first 5 m was 1.3 [s] (SD = 0.09), ranging from 1.28 [s] to 1.33 [s], while the average time of the following 10 m was 2.07 [s] (SD = 0.18), ranging from 2.04 to 2.1 [s]. The average total speed test time equaled 3.37 [s] (SD = 0.21), ranging from 3.33 to 3.38. Statistical analysis did not show significant differences in any of the results between the training days. Conclusions: Most of the goalkeepers felt muscle soreness as an effect of specific goalkeeper training, measured by indicating painful zones on digital pain drawings. In this study, where muscle soreness was induced by technical-tactical specific goalkeeper training, no significant changes were noticed in the speed of performing a motor speed test with reaction choice or on the area of muscle soreness indicated on digital pain drawings, although almost every goalkeeper had a large area of muscle soreness. Discussion: Many studies show that delayed onset muscle soreness (DOMS) causes a decrease in strength, power, range of motion and speed. However, in many cases, these studies are designed to induce high intensity DOMS and then conduct isolated motor skill tests. In this study the objective was not to induce high intensity DOMS but to investigate the effect of muscle pain, which is present naturally during training processes, and then assess its effect on a speed test which reflects real game situations – with a component of reaction choice and change of movement and direction. Approaching the subject from a different viewpoint allows us to see that the reliable assessment of the psychophysical state of players, made by observing their actions on the pitch or even using photocells to measure motion speed, is difficult without an insight into the parameters of soreness that players experience. These can be monitored, for example, through digital pain mapping software.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2020, 32, 4; 27-41
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of bovine serum albumin glycated with glucose, galactose and lactose
Autorzy:
Ledesma-Osuna, Ana
Ramos-Clamont, Gabriela
Vázquez-Moreno, Luz
Powiązania:
https://bibliotekanauki.pl/articles/1040702.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
bovine serum albumin glycoconjugates
Maillard reaction
glycation
Opis:
The non-enzymatic reaction between reducing sugars and proteins, known as glycation, has received increased attention from nutritional and medical research. In addition, there is a large interest in obtaining glycoconjugates of pure well-characterized oligosaccharides for biological research. In this study, glycation of bovine serum albumin (BSA) by d-glucose, d-galactose and d-lactose under dry-heat at 60°C for 30, 60, 120, 180 or 240 min was assessed and the glycated products studied in order to establish their biological recognition by lectins. BSA glycation was monitored using gel electrophoresis, determination of available amino groups and lectin binding assays. The BSA molecular mass increase and glycation sites were investigated by mass spectrometry and through digestion with trypsin and chymotrypsin. Depending on time and type of sugar, differences in BSA conjugation were achieved. Modified BSA revealed reduction of amino groups' availability and slower migration through SDS/PAGE. d-galactose was more reactive than d-glucose or d-lactose, leading to the coupling of 10, 3 and 1 sugar residues, respectively, after 120 minutes of reaction. BSA lysines (K) were the preferred modified amino acids; both K256 and K420 appeared the most available for conjugation. Only BSA-lactose showed biological recognition by specific lectins.
Źródło:
Acta Biochimica Polonica; 2008, 55, 3; 491-497
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Global existence and blow up of solutions for a completely coupled Fujita type system of reaction-diffusion equations
Autorzy:
Rencławowicz, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/1338982.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
reaction-diffusion system
global existence
blow up
Opis:
We examine the parabolic system of three equations $u_t$ - Δu = $v^p$, $v_t$ - Δv = $w^q$, $w_t$ - Δw = $u^r$, x ∈ $ℝ^N$, t > 0 with p, q, r positive numbers, N ≥ 1, and nonnegative, bounded continuous initial values. We obtain global existence and blow up unconditionally (that is, for any initial data). We prove that if pqr ≤ 1 then any solution is global; when pqr > 1 and max(α,β,γ) ≥ N/2 (α, β, γ are defined in terms of p, q, r) then every nontrivial solution exhibits a finite blow up time.
Źródło:
Applicationes Mathematicae; 1998-1999, 25, 3; 313-326
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ wymuszonych oscylacji na wydajność autokatalitycznej reakcji chemicznej
Influence of forced oscillations on the performance of autocatalytic chemical reaction
Autorzy:
Zalewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2072160.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
chaos
oscylacje
reakcja autokatalityczna
oscillations
autocatalytic reaction
Opis:
W pracy została przeanalizowana autokatalityczna izotermiczna reakcja chemiczna prowadzona w przepływowym reaktorze chemicznym z idealnym mieszaniem. W celu określenia wydajności reakcji posłużono się wskaźnikami całkowymi, reprezentującymi średnie stężenia produktów i reagentów. Przedstawiono wpływ zmienności natężenia strumienia zasilającego reaktor na powyższe wskaźniki oraz na przebieg trajektorii czasowych stężeń reagentów i produktów.
Isothermal autocatalytic chemical reaction carried on in a stirred tank reactor is analyzed in the paper. In order to determine the reaction efficiency integral indexes representing average concentrations of reactants and products were used. An impact of variability of reactor feed flow rate on integral indexes and on the course of time trajectory of reactants and products concentrations is showed.
Źródło:
Inżynieria i Aparatura Chemiczna; 2013, 4; 382--383
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of pumice and scoria aggregates for controlling alkali silica reaction
Autorzy:
Tapan, M.
Powiązania:
https://bibliotekanauki.pl/articles/110861.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
alkali-silica reaction
aggregate
pumice
scoria
SEM
Opis:
Turkey has important potential pumices reserves (68% of the reserve of the world) and 56 % of pumice reserve of Turkey is in the East Anatolia Region. It is important to assess huge pumice reserves in Eastern Turkey for its use in the cement and concrete industry. Use of acidic pumice and basic pumice (scoria) as cement additive or aggregate are gaining popularity because of their proven structural/durability properties. This paper presents the results of an investigation to assess the effectiveness of pumice and scoria aggregates in controlling alkali silica reaction (ASR) of alkali silica reactive aggregate using the following test methods: the accelerated mortar bar test (ASTM C 1260) and the scanning electron microscopy technique (SEM). The morphologies, structures and properties of the samples were determined by XRD, ICP-MS, XRF and thin section study. Mortar cubes were specially prepared according to ASTM standards using 10, 20 and 30% pumice or scoria aggregate as alkali silica reactive aggregate replacement. The results are compared with ASTM requirements to assess the suitability of pumice or scoria for preventing alkali silica reactivity. According to the results of these methods, pumice aggregates control the alkali silica reaction whereas scoria aggregates decrease expansion but is not as effective as pumice in preventing ASR. The results of SEM analysis showed alkali silica gel formation and serious decomposition of aggregate texture due to ASR in scoria added mortar bars.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 2; 467-475
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetic Modelling of Betalain Stability and Color Changes in Yogurt During Storage
Autorzy:
Guneser, Onur
Powiązania:
https://bibliotekanauki.pl/articles/1363260.pdf
Data publikacji:
2021-04-20
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
natural pigments
betalains
yogurt
reaction kinetics
color
Opis:
Assessment of the storage stability of betalains added to food during processing is crucial to estimate the shelf-life of colored food products and the potency of natural food colorants. The stability of beetroot betalains in yogurt during storage was evaluated in this study. Kinetic experiments were conducted at storage temperatures of 4°C, 10°C, and 20°C. The relationships were also determined between the betalain degradation and lightness (L*), redness (a*), and yellowness (b*). First-order kinetics was observed in the betalain degradation, and the changes in color parameters of the yogurt samples fitted zero-order kinetics. The activation energy required for the degradation of betalains and changes in L*, a*, and b* was found as 104.9, 67.6, 76.5, and 86.1 kJ/mol, respectively. The half-life period of the degradation of red beet betalains was found as 51.43, 30.91, and 4.54 days at 4°C, 10°C, and 20°C, respectively. Multiple linear regression models were also established for betalain content and color parameters. There was a decrease in betalain content and a* color value in the yogurt colored with a beetroot extract during storage. A significant positive correlation was found between pH, a* value, and betalain content in yogurt, while a significant negative correlation was found between betalain content and L* and b* values. Further studies need to be carried out to reveal the relationship between color parameters and natural pigments in food systems.
Źródło:
Polish Journal of Food and Nutrition Sciences; 2021, 71, 2; 135-145
1230-0322
2083-6007
Pojawia się w:
Polish Journal of Food and Nutrition Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat effects in the reaction of sulfuric acid with ilmenites influenced by initial temperature and acid concentration
Autorzy:
Jabłoński, Maciej
Lubkowski, Krzysztof
Tylutka, Sandra
Ściążko, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1849318.pdf
Data publikacji:
2021
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
ilmenites digestion
sulfuric acid
enthalpy of reaction
Opis:
The influence of temperature and sulfuric acid concentration on the enthalpy and the rate of heat release during the reaction of Norwegian and Australian ilmenites with sulfuric acid was determined. The experimental results obtained from calorimetric measurements were compared with theoretical calculations based on the oxide composition and the phase composition of the raw material. Experimentally determined heat of reaction for Norwegian ilmenite (900–940 kJ/kg) and Australian ilmenite (800–840 kJ/kg) showed good agreement with theoretical calculations based on the phase composition of the raw material. It was found that the enthalpy of ilmenites decomposition reaction does not depend on the concentration of sulfuric acid in the concentration range from 83% to 93%. It was also demonstrated that the temperature and concentration of sulfuric acid have a significant impact on the thermokinetics of the decomposition process, increasing the value of the average rate of temperature change.
Źródło:
Polish Journal of Chemical Technology; 2021, 23, 3; 37-42
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of Iron and Aluminium Powder Pressing on the Course of Shrinkage and Properties of the Fe40Al Phase Obtained by Reaction Sintering
Autorzy:
Berendt-Marchel, M.
Siemiaszko, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2048785.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
intermetallic
powder metallurgy
reaction sintering
mechanical properties
Opis:
The effect of the compaction rate on the structure, microstructure and properties of Fe-Al sinters obtained during the SHS reaction is presented in this paper. It was found that increasing the uniaxial pressing pressure led to the increase of the contact area between iron and aluminium particles, which improved the conduction and lowered heat losses during the self-propagating high-temperature synthesis (SHS) reaction and thus result with a sintered material with an improved phase homogeneity. On the other hand, an increase in the pressing pressure causes air be trapped in the pores and later on reacts with iron and aluminium to form oxides. In this work, the shrinkage course was analysed at six different pressing pressures: 50, 100, 150, 200, 300 and 400 MPa. The green compacts were then subjected to the PAIS process (pressure-assisted induction sintering) at a temperature of 1000°C under a load of 100 kN for 5 min. Such prepared samples were subjected to density, porosity, and microhardness (HV0.1) measurements. X-ray diffraction phase analysis and SEM observations were performed together with EDS chemical composition measurements. For studied chemical composition of the samples and sample geometry, 200 MPa compacting pressure was found to be optimal in order to obtain the best sample homogeneity.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 121-126
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved method of isolation of total nucleic acids from hop plants and grapevine before the RT-PCR by addition of polyvinylpolypyrrolidone
Usprawniona metoda izolacji calkowitych kwasow nukleinowych z chmielu i winorosli przez RT-PCR przez dodanie poliwinylopolipirolidonu
Autorzy:
Cajza, M
Folkman, W.
Powiązania:
https://bibliotekanauki.pl/articles/65582.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
isolation
total nucleic acid
nucleic acid
hop plant
grapevine
RT-PCR method zob.reverse transcription polymerase chain reaction
addition
polyvinylpolypyrrolidone
reverse transcription polymerase chain reaction
polymerase chain reaction
Źródło:
Journal of Plant Protection Research; 2003, 43, 4; 375-380
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alkali - carbonate reaction of aggregates
Reaktywność alkaliczna kruszyw węglanowych
Autorzy:
Góralczyk, S.
Powiązania:
https://bibliotekanauki.pl/articles/216015.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
reaktywność alkalia-węglany
istota reakcji
metody badań
alkali-carbonate reaction of aggregates
essence of reaction
requirements
methodology
Opis:
In the construction industry carbonate aggregates are commonly used in processes such as concrete production. Aggregates which contain (in their mineral composition) dolomite and an admixture of clay minerals and amorphous silica , can react with alkalis. These reactions can lead to a destructive expansion in concrete. This article explains the mechanisms and the essence of this phenomenon. What is more, some effective and fast methods of the estimation and evaluation of Polish aggregates consisting of carbonate rocks suggests effective methods to determine the usefulness of Polish carbonate aggregates in concrete production are discussed in the paper. Underneath the quality criteria to determine the reactivity of the aggregates will be given. It has been agreed that alkaline reaction and expansion are two separate phenomena related to each other genetically. The aggregates in which reactions caused by clay-siliceous admixtures occur are subjected to expansion. Mineral composition of expansive aggregates as well as their texture indicate that epigenetic dolomites with a distinctive texture are the most reactive. The phase transformations do not end with a complete disintegration of dolomite. They have a cyclical character. They consist of interchangeable reactions of dedolomitization and dolomitization of secondary calcite formed as a result of dolomite's disintegration. The secondary calcite can be effected by Mg+2 ions from pores' solutions and it can form a secondary dolomite. The Mg2+ ions originate from brucite [Mg(OH)2], created in dolomitization process. As a consequence of its reaction with silica, brucite can dissolve and enrich secondary calcite with magnesium. Therefore the reactions which take place in reactive carbonate aggregates and concrete that ismade of it are in fact ongoing processes which consist of dolomite's changes into calcite and vice versa. They are reactions between dedolomitization products (brucite, silica) and products from outside (water, alkalis). The described dedolomitization reactions are a phase of the process that enables expansion due to formation of pressure in inter-granular cracks, with pressure being a result of dry clay-minerals' expansion under the influence of water solutions. Loosening of the aggregate's structure as an effect of dedolomitization reaction makes it easier for water solutions to migrate far into the aggregate's grains followed by their contact with clay minerals.
Kruszywa ze skał węglanowych stosowane są powszechnie w budownictwie między innymi do produkcji betonów. Niektóre z nich, zawierające w swym składzie mineralnym obok dolomitu domieszki minerałów ilastych i bezpostaciowej krzemionki, mogą reagować z alkaliami powodując szkodliwą ekspansję w betonach.W artykule opisano istotę i mechanizmy tego zjawiska oraz zaproponowano efektywne metody oceny przydatności polskich kruszyw ze skał węglanowych do produkcji betonów. Podano kryteria jakościowe oceny reaktywności. Ustalono, że reakcje alkaliczne i ekspansja to dwa oddzielne zjawiska, ale genetycznie powiązane ze sobą. Ekspansji podlegają tylko te kruszywa, w których wystąpiły reakcje spowodowane występowaniem domieszek ilasto- krzemionkowych. Skład mineralny kruszyw ekspansywnych oraz ich tekstura wskazują, że szczególnie reaktywne są dolomity epigenetyczne o charakterystycznej teksturze. Przemiany fazowe nie kończą się z chwilą całkowitego rozpadu dolomitu, lecz mają charakter cykliczny. Składają się one z następujących po sobie na przemian reakcji dedolomityzacji i dolomityzacji wtórnego kalcytu powstałego z rozpadu dolomitu. Wtórny kalcyt może ulegać oddziaływaniu jonów Mg+2 znajdujących się w roztworach porowych i tworzyć wtórny dolomit. Jony Mg+2 pochodzą z powstającego w procesie dedolomityzacji brucytu [Mg(OH)2], który w wyniku reakcji z krzemionką (SiO2) może się rozpuszczać i wzbogacać wtórny kalcyt w magnez. Tak więc reakcje zachodzące w reaktywnych kruszywach węglanowych i betonach z nich wykonanych są procesami ciągłymi polegającymi na kolejnych przemianach dolomitu w kalcyt i odwrotnie, a także reakcją pomiędzy produktami dedolomityzacji (brucyt, krzemionka) i produktami dostarczonymi z zewnątrz (woda, alkalia). Opisane reakcje dedolomityzacji są etapem umożliwiającym tworzenie się zjawiska ekspansji w wyniku powstawania w porach międzyziarnowych ciśnienia jako efekt pęcznienia suchych minerałów ilastych pod wpływem roztworów wodnych. Rozluźnienie struktury kruszywa jako efekt reakcji dedolomityzacji ułatwia migrację roztworów wodnych w głąb ziaren kruszywa i ich kontakt z minerałami ilastymi.
Źródło:
Gospodarka Surowcami Mineralnymi; 2012, 28, 1; 45-62
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowoczesne metody pozyskiwania substancji biologicznie aktywnych przy zastosowaniu reakcji wieloskładnikowych ze szczególnym uwzględnieniem reakcji Ugi
New methods of receive biologically active substances in multicomponent reactions with particular focus on Ugi reaction
Autorzy:
Ryng, S.
Jęśkowiak, I.
Powiązania:
https://bibliotekanauki.pl/articles/172211.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
reakcja wieloskładnikowa
reakcja Ugi
synteza organiczna
synteza ukierunkowana na różnorodność
multicomponent reaction
Ugi reaction
diversity-oriented synthesis
Opis:
In the last decade a change of thought has taken place in the pharmaceutical industry which has led to a renaissance of the Multicomponent reactions (MCRs) [1]. Under the inspiration of diversity-oriented-synthesis (DOS), numerous efforts have been devoted to find powerful synthetic tools for rapidly accessing maximum molecular diversity with minimum cost. In the toolbox enabling DOS for generating molecular libraries, MCRs are now recognized as one of the most useful and powerful strategies [2], which provide the highest number of compounds for the least synthetic effort [3]. Following the rapid progress in the research area of MCRs, widespread application has been found in many different areas such as chemical biology, natural product synthesis, pharmaceuticals as well as agrochemistry [2]. The overall aim of a DOS is to generate a small-molecule collection with a high degree of structural, and thus functional, diversity that interrogates large areas of chemical space simultaneously [4]. In Targed-Oriented Synthesis (TOS) a complex target is transformed into a sequence of progressively simpler structures by formally performing chemical reactions in the reverse-synthetic direction [3]. Special subclasses are isocyanide based MCRs (IMCRs). They are particularly interesting because they are more versatile and diverse than the remaining MCRs. Today most MCRs chemistry performed with isocyanides relates to the classical reactions of Passerini and Ugi (Scheme 1)[5]. In Ugi four-component reaction (U-4CR), carboxylic acids, primary amines and oxo components (aldehydes or ketones) react with isocyanides in polar solvents to obtain -amino carboxamides (Schemes 2 and 3). Occasionally however, selective conversion of amide groups into other functional groups is desirable for an increase of diversity of the IMCR-derived compounds [6]. In this reaction two substituted amide groups are formed under release of one equivalent of water. Thus, the U-4CR is an atom-economic and environmentally friendly reaction. It was also shown that water can be used as the solvent. This reaction is typically performed by stirrling the components for approximately 1 day in small quantities of a protic solvent (e.g. methanol or trifluoroethanol) [7]. The examples of Ugi reactions are described in the Schemes 4–10. Multicomponent reactions have become attractive tools in modern synthetic organic chemistry. Among their many advantages, they allow the creation of large chemical libraries of diverse, complex molecular structures, starting from simple materials within a short time frame. Not surprisingly, these particular features have made MCRs especially appealing to medicinal chemists [8].
Źródło:
Wiadomości Chemiczne; 2017, 71, 1-2; 45-63
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolina – pospolity aminokwas wyjątkowy katalizator. Część I, Biosynteza proliny. Wewnątrzcząsteczkowa kondensacja aldolowa
Proline as a common amino acid and an exceptional catalyst. Part I, Proline biosynthesis. Intramolecular aldol reaction
Autorzy:
Wróblewski, M.
Kołodziejska, R.
Studzińska, R.
Karczmarska-Wódzka, A.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/172473.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
biosynteza proliny
mechanizm kondensacji aldolowej
wewnątrzcząsteczkowa reakcja aldolowa
proline biosynthesis
mechanism of aldol reaction
intramolecular aldol reaction
Opis:
In asymmetric synthesis of organic compounds more effective solutions are being looked for which will result in higher yield(s) of product(s) and their high enantioselectivity [1]. One of such solutions is an use of a multilevel and cheap catalyst. Proline used as a catalyst is a substance of natural origin which was synthetically obtained by Willstätter who was carrying out research on hygric acid (Scheme 1) [10]. The cells of many organisms have a suitable enzymatic system essential for proline biosynthesis [15]. So far, three proline biosynthesis pathways have been described: from glutamate (Scheme 3 and 4), ornithine (Scheme 5 and 6), and arginine (Scheme 7) [16–28]. Proline which is obtained as a result of biosynthesis or supplementation is a substrate for many proteins. Characteristic and significant content (about 23%) of this amino acid was observed in collage. In cells proline can play an important role of osmoregulator [31–35] – a protective substance regulating the activity of such enzymes as catalase and peroxidase [36]. Proline as a secondary amine shows exceptional nucleophilicity facilitating imine and enamine formation. Used as a catalyst in aldol reaction makes with substrates like imine or enamine transition state imitating the activity of naturally occurring enzymes for this type of reaction, that is aldolases. In their research Hajos and Parrish, and Eder, Sauer and Wiechert used proline in intramolecular aldol reaction obtaining proper enones (Scheme 9) [60–62]. The process of intramolecular aldol reaction was used for a separation of racemic mixture of diketones (Scheme 10) [63, 64], cyclization of ortho-substituted aromatic aldehydes and ketones (Scheme 11) [65], synthesis of cyclic diketones (Scheme 13) [68] and domino reaction to obtain substituted cyclohexanones from beta-diketones and unsaturated ketones (Scheme 14) [69].
Źródło:
Wiadomości Chemiczne; 2013, 67, 9-10; 801-818
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Exercise and Heat-Load on Simple Reaction Time of University Students
Autorzy:
Chandra, A. M.
Ghosh, S.
Barman, S.
Iqbal, R.
Sadhu, N.
Powiązania:
https://bibliotekanauki.pl/articles/89834.pdf
Data publikacji:
2010
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
reaction time
exercise
heat stress
cognitive performance
Opis:
Visual and auditory simple reaction times for both right and left hands of young university male students were recorded with a simple reaction timer, before and after an exercise schedule without and with elevated temperatures in a climatic chamber. The results indicated a decrease in both visual and auditory reaction times after the exercise, but a marked increase in them was noticed when exercise was performed at elevated temperatures. The difference in reaction times in preferred and nonpreferred hands was negligible at rest, i.e., without any exercise and elevated temperature. However, the difference was significant when exercise was performed at elevated temperatures. Visual reaction time was longer than auditory reaction time in all conditions. The results suggest that in hot industries, increased temperature has a specific rather than general effect on cognitive processes, perception and attentiveness, leading to increased chances of human errors, fatal accidents and loss of productivity.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2010, 16, 4; 497-505
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical solution through mathematical modelling of unsteady MHD flow past a semi-infinite vertical moving plate with chemical reaction and radiation
Autorzy:
Bhandari, A.
Powiązania:
https://bibliotekanauki.pl/articles/178846.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
MHD flow
chemical reaction
radiation
numerical solution
Opis:
In the present manuscript, unsteady magnetohydrodynamic (MHD) flow over a moving porous semi-infinite vertical plate with time-dependent suction has been studied in the presence of chemical reaction and radiation parameters. Time-dependent partial differential equations in the dimensionless form are solved numerically through mathematical modelling in COMSOL Multiphysics. The results are obtained for velocity, temperature and concentration profiles at different times. Steady state results are also presented for different values of physical parameters. The parameters involved in the problem are useful to change the characteristics of velocity, heat transfer and concentration profiles. The numerical solution of partial differential equations involved in the problem is obtained without sacrificing the relevant physical phenomena.
Źródło:
Studia Geotechnica et Mechanica; 2018, 40, 4; 270-281
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Visuomotor processing after progressively increased physical exercise
Autorzy:
Zwierko, Teresa
Lesiakowski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/1055162.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
differentiation of visual signal
exercise
reaction time
Opis:
We assessed the effect of physical effort with increasing intensity on the visuomotor processing in physically active young men (n=22). Subjects performed three 10-minute effort-tests with increasing intensity on a cycloergometer. Each participant was assigned individual workload values below the lactate threshold (40% VO2max), at the lactate threshold (60% VO2max) and above the lactate threshold (80% VO2max). Special Ability Signal Test included in the Vienna Test System (Schuhfried, Austria) was used to examine visuomotor processing. The numbers of correct reactions and the median reaction time as a measure of the speed of the detection process were analyzed. Four Signal test recordings were taken: pre-exercise and immediately after the three subsequent effort tests. The numbers of correct reactions increased after the first effort (40% VO2max) in comparison to the pre-exercise state and then significantly decreased after the third effort test (80% VO2max). In contrast, no significant changes in time of signal detection were observed. Physical effort with high intensity might disturb the visuomotor processing in accordance to the accuracy of the visuospatial differentiation of the relevant signal within irrelevant signals.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2014, 5, 1; 27-34
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł

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