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Wyszukujesz frazę "1-6" wg kryterium: Temat


Tytuł:
Synthesis of some butenolides and study of their antibacterial activity
Autorzy:
Tamma, N.
Gherraf, N.
Powiązania:
https://bibliotekanauki.pl/articles/411700.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Butenolides
addition 1,6 reagents organocuprates
biological activity
Opis:
Butenolides and their analogues represent a wide range of natural compounds of a medical and biological importance. In the last decades, a great number of compounds of various structures, in general from Alkylidene butenolide, were isolated and showed biological activities. In this work we have studied the reactivity of some alkylidene butenolide and their antibacterial activity. the study is of a scientific interest in terms of the synthesis of new compounds (Butenolide 01: 5-hydroxy-5-(1-methoxypropan-2-yl)-4-methylfuran-2(5H)-one, Butenolide 02: 5-(1-methoxypropan-2-yl)-4-methylfuran-2(5H)-one) that have not been studied before by other researchers; and of an economic importance because of its synthesis process which is easy and inexpensive. Moreover, butenolide showed a positive antimicrobial activity (antibiotic) against pathogenic bacteria (mainly Enterobacter hafniae).
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 9, 1; 61-67
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rabbit muscle fructose-1,6-bisphosphatase is phosphorylated in vivo.
Autorzy:
Rakus, Dariusz
Zarzycki, Marek
Dzugaj, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1043652.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
aldolase
muscle
phosphorylation
AMP
fructose-1,6-bisphosphatase
Opis:
Phosphorylated fructose-1,6-bisphosphatase (FBPase) was isolated from rabbit muscle in an SDS/PAGE homogeneous form. Its dephosphorylation with alkaline phosphatase revealed 2.8 moles of inorganic phosphate per mole of FBPase. The phosphorylated FBPase (P-FBPase) differs from the dephosphorylated enzyme in terms of its kinetic properties like Km and kcat, which are two times higher for the phosphorylated FBPase, and in the affinity for aldolase, which is three times lower for the dephosphorylated enzyme. ephosphorylated FBPase can be a substrate for protein kinase A and the amount of phosphate incorporated per FBPase monomer can reach 2-3 molecules. Since interaction of muscle aldolase with muscle FBPase results in desensitisation of the latter toward AMP inhibition (Rakus & Dzugaj, 2000, Biochem. Biophys. Res. Commun. 275, 611-616), phosphorylation may be considered as a way of muscle FBPase activity regulation.
Źródło:
Acta Biochimica Polonica; 2003, 50, 1; 115-121
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diverse expression of N-acetylglucosaminyltransferase V and complex-type β1,6-branched N-glycans in uveal and cutaneous melanoma cells
Autorzy:
Pocheć, Ewa
Rydlewska, Magdalena
Przybyło, Małgorzata
Lityńska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1039114.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
β1,4-N-acetylglucosaminyltransferase III
β1,6-N-acetylglucosaminyltransferase V
bisected GlcNAc
β1,6-branched N-glycans
uveal melanoma
cutaneous melanoma
Opis:
Although both uveal (UM) and cutaneous (CM) melanoma cells derive from the transformed melanocytes, their biology varies significantly in several aspects. Malignant transformation is frequently associated with alternations in cell glycosylation, in particular those concerning branched complex-type N-glycans. These changes occur principally in β1,4-N-acetylglucosaminyltransferase III (GnT-III) that catalyzes the synthesis of glycans with bisected N-acetylglucosamine (GlcNAc) and β1,6-N-acetylglucosaminyltransferase V (GnT-V) that is involved in forming β1,6-branched antenna in complex-type glycans. We searched for the reasons of a different behavior of CM and UM cells in the expression of GnT-III and GnT-V and their oligosaccharide products. Our study showed that UM cells have more β1,6-branched glycans than CM cells, what results from a higher expression of MGAT5 gene encoding GnT-V. The higher β1,6-branching of glycans in UM may contribute to their higher potential to migrate on fibronectin and weaker binding to main extracellular matrix proteins, observed in our previous studies.
Źródło:
Acta Biochimica Polonica; 2015, 62, 2; 323-328
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cylindrical shells made of stainless steel – investigation of postbuckling
Powłoki cylindryczne ze stali nierdzewnej - badanie stanów pokrytycznych
Autorzy:
Stehr, S.
Stranghoner, N.
Powiązania:
https://bibliotekanauki.pl/articles/396574.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
powłoka cylindryczna
stal nierdzewna
obciążenie wiatrem
stan pokrytyczny
EN 1993.1.6
cylindrical shells
stainless steel
wind loading
postbuckling
EN 1993-1-6
Opis:
The relevant load case of open thin-walled shells is often wind loading during construction. Because of the missing stabilization effect of the roof they show a very high sensitivity to buckling which results into higher wall thicknesses. As part of the European RFCS research project BiogaSS the Institute for Metal and Lightweight Structures of the University of Duisburg-Essen carried out investigations on open thin-walled tanks made of austenitic and duplex stainless steels under wind load to study a possible economic advantage which might be gained from the consideration of the elastic postbuckling behaviour. This contribution presents not only experimental and numerical results but also first recommendations regarding the range of possible buckling reduction factors which might be incorporated in future revisions of EN 1993-1-6 and EN 1993-4-2.
Najbardziej adekwatnym przypadkiem obciążenia otwartych, cylindrycznych powłok cienkościennych jest obciążenie wiatrem podczas wznoszenia powłoki. Wobec braku stabilizującego efektu dachu, powłoki wykazują bardzo dużą wrażliwość na wyboczenie, która prowadzi do konieczności zwiększenia grubości ścian powłoki. Instytut Konstrukcji Lekkich i Metalowych Uniwersytetu Duisburg-Essen przeprowadził badania stateczności otwartych zbiorników cienkościennych wykonanych z nierdzewnych blach ze stali austenicznej i ze stali duplex poddanych działaniu obciążenia wiatrem. Celem tych badań było określenie możliwych korzyści ekonomicznych wynikających z uwzględnienia sprężystych stanów pokrytycznych. Badania te były częścią Europejskiego Projektu RFCS BiogaSS. Prezentowana praca przedstawia nie tylko wyniki badań eksperymentalnych i analiz numerycznych, lecz także pierwsze propozycje zaleceń dotyczących zakresu redukcyjnych współczynników wyboczeniowych, które w przyszłości mogą być włączone do norm EN 1993-1-6 i EN 1993-4-2.
Źródło:
Civil and Environmental Engineering Reports; 2017, No. 25(2); 185-197
2080-5187
2450-8594
Pojawia się w:
Civil and Environmental Engineering Reports
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Excitation Functions of Longer and Shorter Lived Radionuclides
Autorzy:
Noori, S.
Akkurt, İ.
Demir, N.
Powiązania:
https://bibliotekanauki.pl/articles/1031916.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
Radionuclides
Gamma Irradiation
TALYS 1.6 nuclear reaction simulation code
Opis:
Nuclear reactions, which are very important from the point of view of human health, may occur during the production of the radiation sources, used in radiotherapy. The nuclear reaction data are needed in the radioisotope production procedure. The total cross section is also important in accelerator technology, in view of radiation protection and safety. In general, the significance of the cross section data for nuclear reactions in radionuclide production programs is firmly established. Gamma irradiation tracers can offer a large amount of information about the anatomy of different organs in the human body. The main purpose of this work was to compare the cross section of longer-shorter lived radionuclides. Theoretical excitation functions have been calculated with TALYS 1.6 nuclear reaction simulation code. The calculated results have been discussed and compared with the experimental data.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1186-1188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradation Characterization and Mechanisms of Warm Rolled Mg-1.6Gd with 95% Reduction Ratio for Biodegradable Implant Applications
Autorzy:
Zakiyuddin, Ahmad
Irawan, Arya Abietta
Susanti, Oknovia
Harjanto, Sri
Powiązania:
https://bibliotekanauki.pl/articles/356740.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biodegradable implants
Mg-1.6Gd
warm rolling
Mg-RE
EIS
Opis:
Mg-1.6Gd binary alloy was subjected to uniaxial warm rolling at a unidirectional and cross-sectional with a reduction ratio of 95% in order to observe the relationship between its microstructural changes to the degradation behavior. The warm rolling was performed at a temperature range of its recrystallization temperature, which were 400°C and 560°C, and a feed rate of 10 mm/min. Degradation behaviors of Mg-1.6Gd binary alloy was evaluated by means of potentiodynamic polarization and hydrogen evolution test in modified Kokubo’s SBF solution at temperature of 37 ± 1ºC. The lowest corrosion rate of 0.126 mm/year derived from potentiodynamic polarization test was showed by unidirectional-rolled specimen at temperature of 560°C. Hydrogen evolution test results showed the lowest hydrogen gas formed during 24 hours of immersion was found on unidirectional-rolled specimen at temperature of 560°C with a rate of 0.268 cc/cm2/hours. While cross rolled specimens showed a high corrosion and hydrogen evolution rate of 20 mm/year and 0.28 cc/cm2/hours.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 3; 1015-1018
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of β-1,3/1,6 glucan dietary supplements on some immunological and hematological health markers in Siberian sturgeon (Acipenser baerii) infected with Aeromonas hydrophila
Autorzy:
Duman, S.
Şahan, A.
Powiązania:
https://bibliotekanauki.pl/articles/16647493.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Acipenser baerii
Aeromanas hydrophila
β-1.3/1.6 glucan
hematology
non-specificimmune parameters
Opis:
This experimental study aimed to investigate some hematological and immunological changes as a result of Aeromanas hydrophila infection in Siberian sturgeon (Acipenser baerii Brandt, 1869). Their feeds were supplemented with β-1,3/1,6 glucan at different ratios, 250 mg/kg (βG 250); 500 mg/kg (βG500) and 750 mg/kg (βG750). To create an experimental infection, 4×106 cfu/ml Aeromonas hydrophila inoculum was intraperitoneally injected to fish. 0.1 ml intraperitoneal bacteria injection was given to the fish in 12 of 15 tanks, each consisting of 10 fish (the fish in the control group were not given bacteria). Considering the βG500 and βG750 group fish as positive (C+) and negative control (C−) groups in terms of hematological parameters, it was found that RBC (erythrocyte) and Hb (hemoglobin) values, as well as RBC indices (MCV, MCHC, MCH) significantly increased. The immunological parameters, including WBC (leukocyte), leukocyte cell percentages (lymphocyte, monocyte, neutrophil, eosinophil), as well as cytokines, including IL-1β, IL-6, IL-8, and TNF-α values showed similar increases in the βG500 and βG750 groups. It was found that the addition of 500 and 750 mg/kg doses of β-1,3/1,6 glucan to the feed stimulated non-specific immunity of fish against bacterial agents and/or septicemic diseases and beta glucan at this dosage range was determined to be ideal for fish health and that it may be a herbal immunostimulant that can be an alternative to many medicaments.
Źródło:
Polish Journal of Veterinary Sciences; 2023, 26, 1; 109-118
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Biolex Beta-HP on phagocytic activity and oxidative metabolism of peripherial blood granulocytes and monocytes in rats intoxicated by cyclophosphamide
Autorzy:
Wojcik, R
Powiązania:
https://bibliotekanauki.pl/articles/32265.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beta-1,3-1,6-D-glucan
cyclophosphamide
rat
phagocytic activity
oxidative metabolism
granulocyte
monocyte
flow cytometry
peripheral blood
immunosuppression
blood neutrophil
Opis:
The objective of this study was to determine the effect of ß-l,3/l,6-D-glucan (Biolex-Beta HP) on the phagocytic activity and oxidative metabolism of peripheral blood granulocytes and monocytes in rats intoxicated by cyclophosphamide. The experimental material comprised 40 adult Wistar rats aged 14 weeks, divided into two equal groups, a control group and an experimental group, each of 20 adult rats, including 10 males and 10 females. In the course of 3 successive days, 20 rats from the experimental group were administered cyclophosphamide intramuscularly at a dose of 50 mg/kg body weight/day. On the 8th day of the experiment, 10 control group (K) rats and 10 experimental group (C) rats were sacrificed. Arterial blood samples were collected and diluted with heparin to determine and compare the phagocytic activity (Phatogest) and oxidative metabolism (Bursttest) of peripheral blood granulocytes and monocytes by flow cytometry. Starting on the 8lh day of the experiment, the feed of the remaining 10 rats from the experimental group (C+G) and 10 rats from the control group (G) was supplemented with Biolex-Beta HP at a dose of 50 mg/kg body weight/day for 14 consecutive days. On day 22, arterial blood samples were collected from all (C+G) and (C) group rats, diluted with heparin to determine and compare the phagocytic activity and oxidative metabolism of peripheral blood granulocytes and monocytes by flow cytometry. The results showed that Biolex-Beta HP modulated the phagocytic activity and oxidative metabolism of blood neutrophils and monocytes suppressed by cyclophosphamide in rats. The immunorestoring activity of Biolex-Beta HP was observed in this study.
Źródło:
Polish Journal of Veterinary Sciences; 2010, 13, 1; 181-188
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An efficient protocol for the synthesis of novel 2-amino-N-(1-(aryl-2-oxo-2Hchromen-3-yl)ethylidene) benzohydrazides act as an antimicrobial agents
Autorzy:
Rola, R. R.
Joshi, H. D.
Powiązania:
https://bibliotekanauki.pl/articles/1031432.pdf
Data publikacji:
2021
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
2-amino-N'-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)benzohydrazides
antimicrobial evaluation
efficient procedure
Opis:
We report here the protocol for the preparation of 2-amino-N'-(1-(aryl-2-oxo-2H-chromen-3-yl)ethylidene)benzohydrazides compounds in moderate to excellent yields (46–86%) within a short reaction time (10–15 min), through a clean and efficient procedure. Additionally, the method has a wide substrate scope and provides an accessible route for the large-scale direct synthesis of 2-amino-N'-(1-(aryl-2-oxo-2H-chromen-3-yl)ethylidene)benzohydrazides. The products were assayed for their in vitro biological assay antimicrobial evaluation against two Gram-negative bacteria Escherichia coli MTCC 442, Pseudomonas aeruginosa MTCC 441 and antifungal activity against Candida albicans MTCC 227, Aspergillus Niger MTCC 282, Aspergillus clavatus MTCC 1323 at different concentrations which compared with ampicillin, chloramphenicol, ciprofloxacin, norfloxacin, nystatin, and greseofulvin in as standard drugs which are presented.
Źródło:
World Scientific News; 2021, 152; 15-26
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New thermoplastic poly(carbonate-urethane) elastomers
Autorzy:
Kultys, A.
Rogulska, M.
Powiązania:
https://bibliotekanauki.pl/articles/779306.pdf
Data publikacji:
2011
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
elastomery termoplastyczne
elastomery poliuretanowe
diole
diizocyjanian 4,4'-difenylometanu
diizocyjanian heksano-1,6-diylu
właściwości termiczne
właściwości mechaniczne
mikroskopia sił atomowych
thermoplastic polyurethane elastomers
poly(hexane-1,6-diyl carbonate) diol
4,4'-diphenylmethane diisocyanate
thermal properties
mechanical properties
atomic force microscopy (AFM)
Opis:
Two series of novel thermoplastic poly(carbonate-urethane) elastomers, with different hard-segment content (30 - 60 wt %), were synthesized by melt polymerization from poly(hexane-1,6-diyl carbonate) diol of Mn = 2000 as a soft segment, 4,4'-diphenylmethane diisocyanate (MDI) or hexane-1,6-diyl diisocyanate (HDI) and 6,6'-[methylenebis(1,4-phenylenemethylenethio)]dihexan-1-ol as a chain extender. The structure and basic properties of the polymers were examined by Fourier transform infrared spectroscopy, X-ray diffraction analysis, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Shore hardness and tensile tests. The resulting TPUs were colorless polymers, showing almost amorphous structures. The MDI-based TPUs showed higher tensile strengths (up to 21.3 MPa vs. 15.8 MPa) and elongations at break (up to 550% vs. 425%), but poorer low-temperature properties than the HDI-based analogs.
Źródło:
Polish Journal of Chemical Technology; 2011, 13, 1; 23-30
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Nanomaterials on Thermal Stability of 1,3,6,8-Tetranitro Carbazole
Autorzy:
Pourmortazavi, S. M.
Rahimi-Nasrabadi, M.
Rai, H.
Jabbarzadeh, Y.
Javidan, A.
Powiązania:
https://bibliotekanauki.pl/articles/358744.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
thermal stability
nanomaterial effect
decomposition kinetics
1,3,6,8-tetranitro carbazole
energetic material
Opis:
1,3,6,8-tetranitro carbazole (TNC) as a secondary explosive is used in composite explosive formulations in order to reduce the sensitivity and increase the stability of the explosive composites. In this work, the thermal stabilities of pure TNC and its nanocomposites prepared via three different nanoparticles were studied by thermal analysis, i.e. differential scanning calorimetery (DSC) and thermogravimetry (TG) techniques. Thermal analysis data revealed that the thermal behavior of pure TNC is significantly different from the nanocomposites studied. Pure TNC decomposed completely during a single step in the temperature range 385-425 °C. However, the addition of nanoparticles to the TNC powder leads to higher thermal stability in comparison with the pure TNC. The decomposition kinetics of TNC and its nanocomposites were studied by non-isothermal DSC at several heating rates. Thermokinetic and thermodynamic parameters corresponding to the thermal decomposition of pure TNC and nanocomposites were computed and compared. The results showed that the addition of nanoparticles to the TNC powder has a considerable effect on the thermal stability of the explosive.
Źródło:
Central European Journal of Energetic Materials; 2017, 14, 1; 201-216
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Analysis on the Influence of the Economic Crisis on Education in some European Countries
Autorzy:
Zaharia, Marian
Popescu, Cătălin
Powiązania:
https://bibliotekanauki.pl/articles/633687.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
economic crisis
first and second stage of tertiary education
USM education level
public expenditure on education
Lisbon objectives in education
ISCED 1_6
Opis:
Purpose – This study intends to present some influences developed during the economic crisis related to the education area in some European countries. The study wants to present a comparative analysis among these European countries.Design/Methodology/Approach – This study is based on the Eurostat data series and is designed due to the statistical data processing.Findings – The study revealed some information and ideas about certain aspects as: changes of population structure by educational attainment level, evolutions of the shares with first and second stage of tertiary education, investments in education and training, age distributions for teachers and trainers, participation rates in education.Research Limitations/Implications – This research is based on Eurostat data series considered relevant by the authors and on some other related analyses or research studies. The paper describes case studies from most of European countries but focuses only on few of them.Practical Implications – This study clarifies the influences of the economic crisis on education in some European countries in order to present a real image related to the evolution of education among Europe. Originality/Value – Even though different studies in the education field were developed, this subject was not analyzed in the manner carried out in this paper.
Źródło:
International Journal of Synergy and Research; 2015, 4, 1
2083-0025
Pojawia się w:
International Journal of Synergy and Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occupational exposure to selected isocyanates in Polish industry
Zawodowe narażenie na wybrane izocyjaniany w polskim przemyśle
Autorzy:
Brzeźnicki, Sławomir
Bonczarowska, Marzena
Powiązania:
https://bibliotekanauki.pl/articles/2165381.pdf
Data publikacji:
2015-07-09
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
izocyjaniany
narażenie zawodowe
poliuretany
4’-metylenobis(fenyloizocyjanian)
toluilenodiizocyjanian
diizocyjanian heksano-1'6-diylu
isocyanates
occupational exposure
polyurethanes
4’-methylenediphenyl diisocyanate
toluene diisocyanate
hexamethylene diisocyanate
Opis:
Background Isocyanates constitute a group of highly reactive, low molecular weight chemicals used worldwide for polyurethane manufacturing. The occupational exposure to these compounds is a major cause of occupational asthma, thus it is very important to monitor their concentration in the workplace atmosphere. The aim of the study was to measure the concentration of 4,4’-methylenediphenyl diisocyanate (MDI; CAS 101-68-8), toluene-2,4-di-isocyanate (2,4-TDI; CAS 584-84-9), toluene-2,6-di-isocyanate (2,6-TDI; CAS 91-08-7) and hexamethylene di-isocyanate (HDI; CAS 822-06-0) in the work environment for evaluation of the occupational exposure to these compounds. Material and Methods Determination of concentrations of selected isocyanates was carried out in 21 manufacturing plants, during different industrial processes. The collected air samples (personal samples) were analyzed by means of the high-performance liquid chromatography (HPLC). Results The presented results represent the 1st data on the occupational exposure to isocyanates in Poland. This set of data is generally indicative of concentrations of analyzed isocyanates that are low and do not exceed the maximum admissible concentration (MAC) values in Poland. Elevated concentrations (above the MAC value) were found only for the TDI in the course of manufacturing of polyurethane foam blocks. Conclusions Results of many studies show that low concentrations of isocyanates (particularly of low volatility like for example MDI) in the air cannot exclude the possibility of additional absorption of these compounds through skin. Taking into consideration all the uncertainties associated with the evaluation of the risk of exposure to isocyanates based solely on measurement of their levels in the air, it would seem that the simultaneous application of environmental and biological monitoring would only facilitate a reliable assessment of the occupational exposure risk. Med Pr 2015;66(3):291–301
Wstęp Izocyjaniany stanowią grupę małocząsteczkowych silnie reaktywnych związków chemicznych szeroko stosowanych do produkcji tworzyw poliuretanowych. Uważa się, że zawodowe narażenie na te związki to jeden z głównych czynników powstawania astmy zawodowej i z tego względu istotne jest stałe monitorowanie ich stężeń w środowisku pracy. Celem pracy było wykonanie pomiarów stężeń metylenobis(fenyloizocyjanianu) (MDI; CAS 101-68-8), diizocyjanianu tolueno-2,4-diylu (2,4-TDI; CAS 584-84-9), diizocyjanianu tolueno-2,6-diylu (2,6-TDI; CAS 91-08-7), diizocyjanianuheksano-1,6-diylu (HDI; CAS 822-06-0) w środowisku pracy jako podstawy do oceny zawodowego narażenia na te związki. Materiał i metody Oznaczenia stężeń wybranych izocyjanianów zostały przeprowadzone w 21 zakładach pracy podczas różnych procesów produkcyjnych. Pobrane próbki powietrza analizowano z zastosowaniem wysokosprawnej chromatografii cieczowej (high-performance liquid chromatography – HPLC). Wyniki Przedstawione wyniki są pierwszymi w Polsce ilościowymi danymi dotyczącymi zawodowego narażenia na izocyjaniany. Wynika z nich, że generalnie stężenia oznaczanych związków pozostają na niskim poziomie i nie przekraczają ustanowionych wartości najwyższego dopuszczalnego stężenia (NDS). Przekroczenia wartości normatywnych stwierdzono jedynie w przypadku TDI podczas produkcji bloków pianki poliuretanowej. Wnioski Wyniki wielu badań wskazują, że w przypadku niskich stężeń izocyjanianów w powietrzu (szczególnie słabo lotnego MDI) nie można wykluczyć możliwości wchłaniania tych związków przez skórę. Biorąc pod uwagę wszystkie niepewności związane z oceną zawodowego narażenia na izocyjaniany dokonywaną wyłącznie w oparciu o pomiary ich stężeń w powietrzu wydaje się, że jedynie jednoczesne stosowanie monitoringu środowiskowego i monitoringu biologicznego mogłoby pozwolić na wiarygodną ocenę narażenia zawodowego. Med. Pr. 2015;66(3):291–301
Źródło:
Medycyna Pracy; 2015, 66, 3; 291-301
0465-5893
2353-1339
Pojawia się w:
Medycyna Pracy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Endothelium dependent factors of vaso cons triction (thromboxane B2) and vaso dilation (6-pros taglandin F1α) in children with primary arterial hypertens ion
Czynniki śródbłonka i skurcz naczyń (tromboksan B2) i rozszerzenie naczyń (6-prostaglandyna F1α) u dzieci z nadciśnieniem tętniczym pierwotnym
Autorzy:
Marushko, Yuriy V.
Hyschak, Tatiana V.
Powiązania:
https://bibliotekanauki.pl/articles/526603.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Opolski. Instytut Nauk o Zdrowiu
Tematy:
primary arterial hypertension
children
thromboxane B2
6-prostaglandin F1α
nadciśnienie pierwotne
dzieci
tromboksan B2
6-prostaglandyna F1α
Opis:
Background: Vasoconstriction and vasodilatation substance imbalance plays a major role in the formation of arterial hypertension. But the ratio between thromboxane B2 and 6-prostaglandin F1α in children with various forms of primary arterial hypertension (PAH) has been insufficiently studied. Aim of the study: The aim of the study is to explore the features of the content of thromboxane B2, 6-keto-PGF-1alfa and their correlation in children with different clinical and pathogenetic forms of PAH. Material and methods: The study involved 83 children aged 9 to 17. The first group included 32 children with stable PAH, the second – 32 children with labile PAH, the third (control group) – 21 children with normal blood pressure. TXB2 and 6-PGF1α serum levels were investigated by ELISA. All the children also underwent ambulatory blood pressure monitoring (ABPM). Results: The average TXB2 levels in boys were 25.05 ±6.43 ng/ml in the group with stable PAH and 27.26 ±11.26 ng/ml in labile PAH examinees, which exceeded the levels in the control group (p < 0.05). The girls’ TXB2 level was elevated in labile PAH respondents (to 11.06 ±1.79 ng/ml, p < 0.05) and did not differ from the control group with stable PAH. The girls’ 6-PGF1α level was up to 3.41 ±0.52 ng/ml in the stable group of PAH and up to 2.63 ±0.25 ng/ml in the group with labile PAH. Conclusions: The violation of the ratio between endothelial vasoconstriction (thromboxane) and vasodilatation (prostacyclin) factors in boys with PAH is due to increased TXB2 levels compared to children with normal blood pressure (p < 0.05). Girls with PAH reflect better compensatory vasodilatation opportunities compared to boys according to the increased prostacyclin production. The latter prevents the progression of endothelial dysfunction and ensures PAH stabilization in girls.
Źródło:
Puls Uczelni; 2015, 3; 3-6
2080-2021
Pojawia się w:
Puls Uczelni
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the copper(II)-aminosilane catalysts in the oxidative polymerization of 2,6-dimethylphenol
Zastosowanie kompleksów Cu(II)-aminosilan jako katalizatorów polimeryzacji utleniającej 2,6-dimetylofenolu
Autorzy:
Firlik, S.
Skupiński, W.
Wielgosz, Z.
Stasiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/947507.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
poly(phenylene oxide)
poly(2,6-dimethyl-1,4-phenylene ether)
oxidative polymerization
2,6-dimethylphenol
aminosilane
poli(tlenek fenylenu)
poli(eter 2,6-dimetylo-1,4-fenylenu)
polimeryzacja utleniająca
2,6-dimetylofenol
aminosilan
Opis:
The aim of this work was to examine the aminosilane ligands for the copper(II) salts and their application as catalysts for the oxidative polymerization of 2,6-dimethylphenol leading to poly(2,6-dimethyl-1,4-phenylene ether) (PPE) [also known as poly(phenylene oxide) (PPO)] formation. As aminosilane ligands, silane derivatives containing primary and/or secondary amino groups were tested. Among aminosilanes used, PPE was only obtained when N-methylaminopropyltrimetoxysilane (MAPTMS) as a ligand for copper(II) was used. CuCl2 and CuBr2 were compared as catalyst precursors for 2,6-dimethylphenol polymerization and influence of N/Cu molar ratio in the range from 80 to 160 on PPE yield and its Mw was tested. It was observed, that with increasing N/Cu molar ratio from 80 to 120, both PPE yield and Mw increased. PPE with the highest Mw was obtained when CuBr2-MAPTMS as acatalyst was used. At N/Cu molar ratio equal to 160, a decrease in PPE Mw obtained with use of both precursors and decrease in PPE yield for CuCl2-MAPTMS catalyst were noticed. The condensed nanoorganosilicon particles of spherical shape well dispersed in PPE were determined in the polymer matrix. The UV-Vis studies showed that, strong ligand field of the aminosilane ligand easier electron transfer from monomer to Cu(II) and thus polymerization facilitate.
Silany zawierające pierwszorzędową lub/i drugorzędową grupę aminową zastosowano w charakterze ligandów w kompleksach soli miedzi(II), które następnie użyto w polimeryzacji utleniającej 2,6-dimetylofenolu (2,6-DMP), w wyniku której otrzymano poli(eter 2,6-dimetylo-1,4-fenylenu) (PPE) znany też jako poli(tlenek fenylenu) (PPO). Spośród przebadanych aminosilanów, jedynie N-metyloaminopropylotrimetoksysilan (MAPTMS) — jako ligand Cu(II) — wykazywał aktywność w reakcji syntezy PPE. Porównano aktywność CuCl2 i CuBr2 jako prekursorów katalizatora polimeryzacji 2,6-dimetylofenolu i zbadano wpływ stosunku molowego N/Cu, w zakresie 80—160, na wydajność reakcji otrzymywania PPE i na jego wagowo średni ciężar cząsteczkowy (Mw). Stwierdzono, że zwiększenie stosunku molowego N/Cu w zakresie 80—120 powoduje zarówno wzrost wydajności polimeryzacji utleniającej 2,6-DMP, jak i ciężaru cząsteczkowego PPE. Polimer o największym Mw otrzymano przy użyciu katalizatora CuBr2-MAPTMS. Przy stosunku molowym N/Cu = 160 zaobserwowano spadek ciężaru cząsteczkowego PPE uzyskanego za pomocą obydwu prekursorów oraz, w przypadku zastosowania CuCl2-MAPTMS jako katalizatora, zmniejszenie wydajności polimeryzacji utleniającej. Ponadto, stwierdzono obecność zdyspergowanych w osnowie PPE krzemoorganicznych nanocząstek o sferycznym kształcie. Badania UV-Vis wykazały, że do inicjacji polimeryzacji 2,6-DMP konieczne jest silne, wywoływane przez aminosilan, pole ligandów, które ułatwia przeniesienie elektronu z monomeru do Cu(II).
Źródło:
Polimery; 2015, 60, 6; 372-376
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł

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