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Tytuł:
Microplastics and endocrine-disrupting chemicals released from disposable hot beverage cups and from teabags, and their evaluation in terms of human health safety
Autorzy:
Tabakoglu, N.
Sezer, K.
Çelik, S.
Powiązania:
https://bibliotekanauki.pl/articles/53394024.pdf
Data publikacji:
2024
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Opis:
Microplastics (MPs) are pollutants that contaminate resources such as water, air, and soil. Humans can be exposed to microplastics through inhalation, digestion, or dermal contact. The use of disposable paper and plastic cups, as well as teabags, is widespread. Cups are usually made of plastic, and teabags are generally made of half-synthetic cellulose. This study aims to draw attention to their effects on human health by analyzing MPs due to contact with plastic paper cups and teabags with a hot aqueous solution (50°C, 70°C, and 90°C). This study used scanning electron microscopy (SEM), high-performance liquid chromatography, and mass spectrometry (LC-MS/MS), and the results were confirmed by Fourier transform infrared spectroscopy (FTIR). The number of MP particles released from teabags increased to 4.59 x 104 particles cm-3, while in paper cups and plastic cups, MP particle numbers elevated to 2.94 x 104 particles cm-3 and 2.11 x 104 particles cm-3, respectively. Total phthalate compound concentrations determined in aqueous solution samples were 1.74-2.42 μg dm-3 in teabags, 1.49-2.40 μg dm-3 in paper cups, 1.20 - 1.28 μg dm-3 in plastic cups; Bisphenol A concentration ranges were determined as 0.015-0.045 μg dm-3 in plastic cups, 0.006-0.011 μg dm-3 in teabags and 0.005-0.006 μg dm-3 in paper cups. Consumption of tea or coffee that comes into contact with disposable plastics daily may increase the daily MP intake and cause health problems in the future.
Źródło:
Journal of Elementology; 2024, 29, 1; 245-263
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Boric Acid Content on the Structural and Optical Properties of MnS Films Prepared by Spray Pyrolysis Technique
Autorzy:
Bedır, M.
Öztaş, M.
Çelik, S.
Özdemır, T.
Powiązania:
https://bibliotekanauki.pl/articles/1205283.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Rs
78.28.-e
61.72.Vv
61.05.cp
68.55.Jk
Opis:
Boron doped MnS films were obtained by the spray pyrolysis method using the boric acid ($H_3BO_3$) as dopant source at a substrate temperature of 350°C. The spray pyrolysis method has a wide range of application areas with a low cost well-suited for the manufacture of solar cells. The properties of boron doped MnS films were investigated as a function of doping concentration. The X-ray analysis showed that the films were polycrystalline fitting well with a hexagonal structure and have preferred orientation in the [002] direction. The optical band gap of the undoped and boron doped MnS films were found to vary from 3.38 to 3.20 eV. The changes observed in the energy band gap and structural properties of the films related to the boric acid concentration are discussed in detail.
Źródło:
Acta Physica Polonica A; 2014, 126, 3; 840-844
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Corporate governance and performance of the financial firms in Bahrain
Ład korporacyjny a wyniki firm finansowych w Bahrain
Autorzy:
Aktan, B.
Turen, S.
Tvaronavičienė, M.
Celik, S.
Alsadeh, H. A.
Powiązania:
https://bibliotekanauki.pl/articles/406241.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska
Tematy:
corporate governance
firm performance
emerging market
Bahrain
ład korporacyjny
wydajność firmy
rozwijający się rynek
Opis:
The aim of this paper is to explore the relationship between corporate governance and performance of the financial firms in the Kingdom of Bahrain. The study uses annual data of all listed financial firms on the Bahrain Bourse over the period of 2011-2016. The results show that board size, ownership concentration and auditor’s reputation have a positive and significant impact on firms’ return on assets (ROA), whereas the percentage of independent directors and the annual number of board meetings have negative and significant impact on firms’ return on equity (ROE). CEO duality is found to not be an important determinant factor of firms’ performance, as the results suggest that it shows insignificant effect on ROA, ROE and stock returns (SPR). Furthermore, firm’s size and leverage are found to have negative and insignificant relationship with firms’ performance.
Celem artykułu jest zbadanie związku między ładem korporacyjnym a wynikami firm finansowych w Królestwie Bahrajnu. W badaniu wykorzystano roczne dane wszystkich notowanych firm finansowych w Bahrajnie w okresie 2011-2016. Wyniki pokazują, że wielkość zarządu, koncentracja własności i reputacja audytora mają pozytywny i znaczący wpływ na rentowność aktywów przedsiębiorstw (ROA), podczas gdy odsetek niezależnych dyrektorów i roczna liczba posiedzeń zarządu mają negatywny i znaczący wpływ na przedsiębiorstwa z kapitałem własnym (ROE). Dualizm dyrektorów generalnych nie jest istotnym czynnikiem determinującym wydajność firm, ponieważ wyniki sugerują, że ma on niewielki wpływ na ROA, ROE i stopy zwrotu (SPR). Ponadto stwierdzono, że wielkość firmy i jej wpływ mają negatywny i nieistotny związek z jej wydajnością.
Źródło:
Polish Journal of Management Studies; 2018, 17, 1; 39-58
2081-7452
Pojawia się w:
Polish Journal of Management Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of selective retention of Cd-Ni ions from aqueous solutions by polymer enhanced ultrafiltration
Autorzy:
Can, Muhammed F.
Arslan, Fatma
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/2146925.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cadmium
nickel
polymer enhanced ultrafiltration
polyethylenimine (PEI)
selective heavy metal ion retention
Opis:
Polymer enhanced ultrafiltration (PEUF) technique economically enables separation and/or retention of various heavy metal ions from aqueous solutions for environmental and engineering problems. Polyethylenimine as the water-soluble complexation agent utilized to interact with heavy metal ions of Cd and Ni as cations in ultrafiltration experiments were modeled with protonation data to understand the mechanism. Test runs showed that an enrichment coefficient (the ratio of Cd over Ni in permeate) up to 10 was obtained at pH 4.2 in the temperature range of 20-22oC, whereas full retention of both cations is possible above pH 5.0 and those results are highly compatible with the model developed.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 151913
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of cold storage on the bioactive components and physical properties of caucasian whortleberry (Vaccinium arctostaphylos l.). a preliminary study
Wpływ przechowywania w chłodni na bioaktywne składniki i właściwości fizyczne borówki kaukaskiej (Vaccinium arctostaphylos l.) badanie wstępne
Autorzy:
Ozturk, B.
Karakaya, O.
Celik, S.M.
Karakaya, M.
Guler, S.K.
Yarilgac, T.
Aydin, H.
Ozturk, A.
Powiązania:
https://bibliotekanauki.pl/articles/11543339.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
In this study, antioxidant activity (AA), total phenolics (TP), total flavonoids (TF), individual phenolic compounds (IPCs), vitamin C and six other fruit characteristics including weight loss, flesh firmness, color, soluble solids content (SSC), dry matter and titratable acidity (TA) of Caucasian whortleberry fruits (Vaccinium arctostaphylos L.) were determined at harvest and at a week postharvest intervals throughout the cold storage at 0°C for 4 weeks. Significant decreases were observed in fruit weight and flesh firmness during the cold storage period. While L* and chroma values decreased significantly, an increase was observed in hue angle values. Significant increases were observed in dry matter, but decreases were observed in SSC, TA and vitamin C contents. Caucasian whortleberry fruits had quite high polyphenol contents. Total phenolics (TP), total flavonoids (TF), antioxidant activity (AA) (according to ABTS+, DPPH· and FRAP antioxidant tests) and individual phenolic compounds (IPCs) significantly decreased throughout the cold storage. Chlorogenic acid was the major phenolic in Caucasian whortleberry fruits. It was concluded that Caucasian whortleberry fruits with high phenolic compound and flavonoid levels might serve a potential antioxidant source.
Zbadano aktywność antyoksydacyjną (AA), całkowitą zawartość fenoli (TP), flawonoidów (TF), indywidualnych związków fenolowych (IPC), witaminy C oraz sześć innych cech, takich jak utrata wagi, zwartość miąższu, barwa, zawartość rozpuszczalnych substancji stałych (SSC), sucha masa oraz kwasowość (TA) owoców borówki kaukaskiej (Vaccinium arctostaphylos L.) podczas zbioru oraz z tygodniowymi przerwami po zbiorach w czasie całego okresu przechowywania w chłodni w temperaturze 0°C przez 4 tygodnie. Zaobserwowano istotny spadek masy owoców i zwartości miąższu podczas okresu przechowywania w chłodni. Wartości barwy zmniejszyły się istotnie, natomiast zaobserwowano wzrost wartości kąta odcienia. Zaobserwowano istotny wzrost suchej masy, ale spadek został zanotowany w zawartości SSC, TA oraz witaminy C. Owoce borówki kaukaskiej miały dość wysoką zawartość polifenoli. Całkowita zawartość fenoli (TP), flawonoidów (TF), aktywność antyoksydacyjna (AA) (według testów antyoksydacyjnych ABTS+, DPPH· i FRAP) oraz indywidualne związki fenolowe (IPC) istotnie zmniejszyły się w okresie przechowywania w chłodni. Kwas chlorogenowy był głównym fenolem w owocach borówki kaukaskiej. Wyciągnięto wniosek, że owoce borówki kaukaskiej o wysokim poziomie związków fenolowych i flawonoidów mogą służyć za potencjalne źródło antyoksydantów.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2016, 15, 2; 77-93
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of crystallinity and surface silanol groups on rheological properties of different sepiolites
Autorzy:
Çınar, Mustafa
Gülgönül, Ilhan
Ozdemir, Orhan
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/2146875.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sepiolite
rheology
crystallinity
pH
Opis:
In this study, differences in the rheological properties of three different types of brown sepiolites (K1, K2, and K3) along with one beige (B) sepiolite with different physicochemical properties were explained based on their crystallinity and level of surface silanol groups. Towards this aim, SEM images, XRD and chemical analyses, cation exchange capacity (CEC), and water absorption tests were conducted along with surface area measurements and time-dependent pH profiles. The pH profiles at 3% by wt. revealed that each sepiolite sample attained the equilibrium at different times. These differences showed a parallel behavior with the degree of crystallinity. While sepiolite with better crystallinity (K1) was rather slow in reaching the equilibrium pH, the sepiolites with poor crystallinity (B and K3) reached their equilibrium pH more quickly. The rheological studies conducted with different sepiolites at 3% solids concentration exhibited time-dependent flow of the Bingham plastic model and thixotropic. Differences observed in the rheological behavior of sepiolites were found to correlate with the fiber size, CEC, surface area, and water absorption. The results further indicated that sepiolites with low crystallinity or high level of surface silanol groups (K3 and B sepiolites) show the best rheological properties.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 153947
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphological changes of glass bead particles upon an abrasive blasting as characterized by settling and flotation experiments
Autorzy:
Behzad, Vaziri Hassas
Güven, Onur
Baştürkcü, Esra
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/1448218.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
roundness
flotation
settling rate
energy barrier
Opis:
The recent developments in mineral processing led researchers to look for alternative methods and propose new mechanisms for enhancing the efficiency of relatively costly processes (e.g., flotation, aggregation), where especially dealing with fine particles. Finer the particles, the higher the role of their surface on their behavior and properties. The importance of particle morphology becomes even clearer when particle-particle and particle-bubble interactions are considered. In this study, the effect of particle shape “roundness” on the surface wettability and flotation response was investigated upon producing fine particles with the “abrasion blasting” method. In order to provide a fundamental perspective, adsorption measurements were also carried out along with the flotation experiments under the same conditions. In addition to these, zeta potential measurements were also carried out with both spherical and blasted particles as a function of collector concentration. The results suggested that the roundness of particles decreased up to a certain nozzle pressure value, which was followed by higher adsorption degrees and consequently higher flotation recoveries. Additionally, settling rate tests were also performed with very fine material to show the effect of particle morphology on particle-particle interactions. The results showed that while lower settling rate values were obtained for spherical ones, higher values were obtained in the case of the ground and blasted samples in the presence of DI water. It was concluded from this study that the “Abrasive blasting method” could be an effective alternative for tuning the surface morphology of particles and their wettability, which in turn can affect the particle interactions in the system.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 2; 157-168
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphological analysis of organo-montmorillonites via MD simulations
Autorzy:
Karataş, Deniz
Tekin, Adem
Can, Muhammed F.
Xu, Zhenghe
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/2146936.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
organo-montmorillonite
tetradecyl dimethyl ethyl benzyl ammonium chloride
molecular dynamics simulation
cation exchange capacity
binding energy
Opis:
Adsorption on clay surfaces has been studied intensively in recent years. The most curious subject of these studies, which are generally experimental, is how the surfactants are adsorbed at the atomic level to the surface. In this study, the adsorption of quaternary amine salt (tetradecyl dimethyl ethyl benzyl ammonium chloride–TDEBAC) to sodium montmorillonite (Na-MMT) with various cation exchange capacities (CEC) was investigated by using Molecular Dynamics (MD) simulation. In the simulations, as in the experimental studies, it was revealed that the surfactants were both adsorbed on to basal surfaces and settled between the layers. From the morphological analysis obtained from MD simulations, it was calculated that the inter-molecular interaction between the layers was higher than on the basal surface. For example, for the model with 118 CEC motif, the binding energy of all three surfactants in the models with the hydrophilic heads facing the same direction was calculated as -678.18 kcal/mol at the basal surface, while this value was found to be -688.90 kcal/mol in the interlayer. The more striking result is that in the simulations made by turning the head of the middle one of the three surfactants towards the tails of the right and left ones, only -34.86 kcal/mol binding energy was calculated on the basal surface, while this value was -525.63 kcal/mol in the interlayer. As compared middle reversed surfactant models with the same direction ones, despite increased CEC the intermolecular interaction decreased for the basal surface, but the interaction increased between the layers.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152499
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved flotation of heat treated lignite with saline solutions containing mono and multivalent ions
Autorzy:
Ozdemir, O.
Ersoy, O. F.
Guven, O.
Turgut, H.
Cinar, M.
Çelik, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/109640.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
heat treatment
lignite
DLVO
Saline Solutions
Opis:
Flotation of lignites is inherently difficult. However, pre-heat treatment of coal is also known to make coal surfaces more hydrophobic possibly through removal of water entrapped in the structure of coal. In this context, the objective of this study was, therefore, to determine changes in the hydrophobicity of some lignites under moderately controlled heat treatment and correlate the flotation response of lignites in different salt solutions of NaCl, KCl, CaCl2, and MgCl2 without using any reagent. The results of flotation tests suggested that under the present test conditions, it was possible to float thermally pre-treated lignite samples of partially hydrophobic character in salt solutions in the absence of collector and frother. In addition, the effect of heat treatment on hydrophobicity, and in turn flotation was explained by a theoretical model based on extended DLVO interactions to quantify the effects of both heat treatment and salt concentration on bubble-particle interactions. The results of theoretical modeling suggested that the removal of hydrogen containing groups from coal surfaces significantly contribute to the electrical double layer and hydrophobic forces that govern the magnitude of energetic barrier and also the extent of bubble-particle attachment.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1070-1082
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of particle shape properties on selective separation of chromite from serpentine by flotation
Autorzy:
Guven, Onur
Serdengecti, M. Tayhan
Tunc, Berivan
Ozdemir, Orhan
Karaagaclioglu, Ibrahim E.
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/1845205.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chromite
serpentine
morphology
flotation
mineral mixtures
Opis:
Although many studies have been conducted on the morphological variations and its effects on flotation recoveries of a single mineral system, a systematic study for the flotation behavior of mixtures of minerals has not dwelled much. In this study, th flotation behavior of chromite and serpentine minerals was investigated to distinguish and isolate the contribution of morphology in single and binary systems. For this purpose, the shape analyses for the minerals ground as single and mixture were performed, and their flotation behaviors determined with the micro-flotation experiments. Additionally, the zeta potential measurements were carried out in the presence of sodium oleate as a collector. The shape analysis of the ground samples showed that while the roundness values of chromite and serpentine (gangue) minerals as single were quite different, the particle shape of chromite favored serpentine in the mixture system which in turn suggested that the mineral with the high hardness value dominates the shape characteristics in binary grinding conditions. Accordingly, while the flotation characteristics of chromite in the mixture followed the same trend with the flotation of a single chromite system as a function of particle shape, almost a reverse trend was obtained for the shape and flotation of serpentine in the mixture compared to a single serpentine system. Thus, at roundness values of chromite particles from 0.797 to 0.732, the flotation recoveries of chromite in the mixture increased from 51.0% to 75.4%. On the other hand, likewise chromite, the flotation recoveries of serpentine increased from 20.0% to 37.3% proportional to the roundness range of 0.757 and 0.709. These findings in turn showed that the grinding conditions dictate the soft component to be monitored by the harder and denser component which dominates the angularity and floatability of the mixture.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 5; 818-828
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimum separation route for semi bituminous coal using semi-pilot scale pneumatic stratification jig
Autorzy:
Boylu, F.
Cetinel, T.
Guven, O.
Karakas, F.
Cinku, K.
Karaagaclioglu, I. E.
Celik, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/109366.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
semibituminous coal
dry coal cleaning
Allair jig
optimization
Opis:
Nowadays, dry beneficiation technologies with an air dense medium fluidized bed come into prominence in the field of coal preparation. In this study, the optimum conditions for different operational parameters such as discharge stargate rate, pulsation frequency, and superficial air velocity were investigated on separation of semi bituminous coal from Soma (Imbat) region using a semi pilot scale Allair jig unit. The experimental studies were carried out with two coal size fractions of -15+4 and -4+1 mm by applying rougher and scavenging stages. After the optimization of each parameter, the results for the rougher stages indicated that clean coal products could be obtained with 11.80% and 16.74% ash contents for -15+4 mm and -4+1 mm size ranges, respectively. In addition, discardable tailings with 65.44% and 60.95 % ash contents could be obtained as the result for the scavenging stages. Finally, the combination of these results for -15+1 mm size exhibited that 59.80% of the feed material with 37.70% ash content can be upgraded to clean coal products with low ash content as 19.80% while the remaining part was discarded as tailings with 68.60% ash content. These values suggested that optimizing the operational parameters of unit brings better results which are applicable in industrial application of dry processes compared to wet processes.
Źródło:
Physicochemical Problems of Mineral Processing; 2015, 51, 2; 559-573
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Pressure Effect on Glass Formation and Cluster Structure Evolution during Cooling Process of PdNi Alloy: A Molecular Dynamics Study
Autorzy:
Kazanc, S.
Celik, F.
Powiązania:
https://bibliotekanauki.pl/articles/1195946.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.pe
83.10.Rs
34.20.Cf
Opis:
Based on the embedded atom method a molecular dynamics simulation technique has been used to study the glass formation and atomic short range order in Pd-Ni binary alloy. By using radial distribution functions and Honeycutt-Andersen pair analysis methods, the structural development of this alloy is studied by quenching from the liquid at two different cooling rates and under 0 and 5 GPa pressures. The results show that the variation of local atomic bonded pairs is of great importance to understand the glass formation process and increase of the number of the ideal icosahedra under high pressure contributes to more ideal glass formation of model alloy.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 49-53
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some physical properties of pomegranate cv. Eksinar
Autorzy:
Celik, A
Ercisli, S.
Powiązania:
https://bibliotekanauki.pl/articles/25105.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
physical property
pomegranate
Eksinar cultivar
Punica granatum
porosity
surface area
fruit mass
fruit volume
skin colour
Źródło:
International Agrophysics; 2009, 23, 3; 295-298
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculations of Transition Probabilities for Some Excited Levels of Na I
Autorzy:
Çelik, G.
Ateş, Ş.
Powiązania:
https://bibliotekanauki.pl/articles/1812351.pdf
Data publikacji:
2008-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.10.+z
Opis:
Transition probabilities are calculated for individual and multiplet lines between some excited states in neutral sodium by using the weakest bound electron potential model theory. In the determination of parameters required for calculation of transition probabilities, we employed numerical non-relativistic Hartree-Fock wave functions for expectation values of radii in all levels. The necessary energy values were taken from experimental energy data in the literature. The obtained results were compared with accepted values taken from National Institute of Standards and Technology data and multi-configurational Hartree-Fock results given by Fischer. A good agreement was observed in related excited states.
Źródło:
Acta Physica Polonica A; 2008, 113, 6; 1619-1627
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oscillator Strengths for Allowed Transitions in Li(II)
Autorzy:
Ateş, Ş.
Çelik, G.
Powiązania:
https://bibliotekanauki.pl/articles/1807774.pdf
Data publikacji:
2009-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.15.ag
32.70.Cs
Opis:
Electric dipole oscillator strengths have been computed for transitions between both multiplet and individual lines in the Li(II) ion. The weakest bound electron potential model theory has been used. We have employed both numerical Coulomb approximation wave functions and numerical non-relativistic Hartree-Fock wave functions in the determination of expectation values of radii. The necessary energy values have been taken from experimental ionization energies. The oscillator strengths calculated with parameters obtained by using the two different wave functions have been compared not only to each other but also to other data taken from literature. A good agreement with results in literature has been obtained.
Źródło:
Acta Physica Polonica A; 2009, 116, 2; 169-175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiative lifetimes for singly ionized beryllium
Autorzy:
Çelik, G.
Atalay, B.
Ateş, Ş.
Powiązania:
https://bibliotekanauki.pl/articles/1157856.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.15.ag
32.70.Cs
Opis:
The theoretical lifetimes for singly ionized beryllium (Be II) have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory under the assumption of the LS coupling scheme. In the calculations, many states are considered. Some lifetime values for highly excited levels have been obtained using these methods. The lifetimes presented in this work have been compared with the early theoretical calculations and measurements presented in the literature. A good agreement with the results in the literature has been obtained.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 705-709
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the usability of cubic boron nitride cutting tools as an alternative to diamond cutting tools for the aircraft industry
Badanie użyteczności narzędzi tnących z regularnego azotku boru jako alternatywy dla diamentowych narzędzi tnących
Autorzy:
Islak, S.
Kir, D.
Çelik, H.
Powiązania:
https://bibliotekanauki.pl/articles/353631.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CBN cutting tools
hot-pressing technique
wear
narzędzia skrawające
technika prasowania na gorąco
zużycie
Opis:
Diamond and cubic boron nitride (cBN) cutting segments were produced using hot pressing technique for this study to be used in cutting natural stone. cBN grains were added to bronze powder, the chosen matrix, at a rate of 0%, 20%, 40%, 60%, 80%, and 100% (according to percentage by weight). Segments were produced under a pressure of 35 MPa, at a sintering temperature of 600°C, over a sintering time of 3 minutes. The cutting properties of the produced segments were determined by cutting Ankara andesite. A Scanning Electron Microscope (SEM) and an X-Ray Diffractometer (XRD) were used to analyse the microstructure, phase compound, and wear surfaces of each segment type.
Diamentowe i wytworzone z regularnego azotku boru (cBN) techniką prasowania na gorąco segmenty tnące zostały zastosowane do cięcia kamienia naturalnego. Ziarna cBN dodano do proszku brązu (matrycy) w ilości 0%, 20%, 40%, 60%, 80% i 100% (wagowo). Segmenty wytworzono pod ciśnieniem 35 MPa, w temperaturze spiekania 600 C, w czasie 3 minut. Właściwości tnące wytworzonych segmentów zostały określone przez cięcie andezytu. Skaningowej mikroskopii elektronowej (SEM) i dyfrakcji rentgenowskiej (XRD) użyto do analizy mikrostruktury, składu fazowego, oraz zużycia powierzchni każdego typu segmentu.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 4; 1119-1123
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Excited-State Ionization Potentials for Lithium-Like Sequence Using Weakest Bound Electron Potential Model Theory
Autorzy:
Çelik, G.
Yildiz, M.
Kiliç, H. Ş.
Powiązania:
https://bibliotekanauki.pl/articles/2047731.pdf
Data publikacji:
2007-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.10.-f
31.50.-x
Opis:
In this work, the theoretical calculation of excited-state ionization potentials for 1s$\text{}^{2}$2$\text{}_{p}$ $\text{}^{2}$P$\text{}_{1}\text{}_{/}\text{}_{2}$ , 1s$\text{}^{2}$3$\text{}_{s}^{2}$S$\text{}_{1}\text{}_{/}\text{}_{2}$ , 1s$\text{}^{2}$3$\text{}_{d}^{2}$D$\text{}_{1}\text{}_{/}\text{}_{2}$ , 1s$\text{}^{2}$4$\text{}_{s}^{2}$S$\text{}_{1}\text{}_{/}\text{}_{2}$ , 1s$\text{}^{2}$4$\text{}_{p}^{2}$P$\text{}_{1}\text{}_{/}\text{}_{2}$ , and 1s$\text{}^{2}$4$\text{}_{d}^{2}$D$\text{}_{1}\text{}_{/}\text{}_{2}$ iso-spectrum series of lithium-like elements were carried out using a weakest bound electron potential model theory for nuclear charges from Z=3 to Z=18. The Breit-Pauli approximation was used for relativistic contributions. The obtained values are compared with the experimental results from literature. The overall agreement between data obtained in this work and experimental data from literature can appear to be quite good being generally within 0.1% of experimental values.
Źródło:
Acta Physica Polonica A; 2007, 112, 3; 485-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tribological Characterization of Al-bronzes Used as Mold Materials
Autorzy:
Atapek, Ş. H.
Aktaş Çelik, G.
Polat, Ş.
Pisarek, B.
Powiązania:
https://bibliotekanauki.pl/articles/383212.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wear resistant
aluminium bronze
mechanical properties
tribological properties
tribocorrosion resistance
zużycie ścierne
brąz aluminiowy
właściwości mechaniczne
właściwości trybologiczne
odporność tribokorozyjna
Opis:
Among the copper based alloys, Cu-Al-X bronzes are commonly used as mold materials due to their superior physical and chemical properties. Mold materials suffer from both wear and corrosion, thus, it is necessary to know which one of the competitive phenomenon is dominant during the service conditions. In this study, tribo-corrosion behavior of CuAl10Ni5Fe4 and CuAl14Fe4Mn2Co alloys were studied and electrochemical measurements were carried out using three electrode system in 3.5 % NaCl solution in order to evaluate their corrosion resistance. In tribo-corrosion tests, alloys were tested against zirconia ball in 3.5 % NaCl solution, under 10N load with 0.04 m/s sliding speed during 300 and 600 m. The results indicate that (i) CuAl10Ni5Fe4 alloy is more resistant to NaCl solution compared to CuAl14Fe4Mn2Co alloy that has major galvanic cells within its matrix, (ii) although CuAl10Ni5Fe4 alloy has lower coefficient of friction value, it suffers from wear under dry sliding conditions, (iii) as the sliding distance increases, corrosion products on CuAl14Fe4Mn2Co surface increase at a higher rate compared to CuAl10Ni5Fe4 leading to a decrease in volume loss due to the lubricant effect of copper oxides.
Źródło:
Archives of Foundry Engineering; 2017, 17, 4; 7-12
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural and Mechanical Characterization of Solidified Austenitic Stainless Steels
Autorzy:
Celik, A. G.
Polat, S.
Atapek, S. H.
Haidemenopoulos, G. N.
Powiązania:
https://bibliotekanauki.pl/articles/380707.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
theory of crystallization
Thermo-Calc
metallography
microstructure
tribology
stal nierdzewna
stal austenityczna
zestalenie
badanie mikrostrukturalne
badanie trybologiczne
oprogramowanie
Opis:
Among the family of stainless steels, cast austenitic stainless steels (CASSs) are preferably used due to their high mechanical properties and corrosion resistance. These steels owe their properties to their microstructural features consisting of an austenitic matrix and skeletal or lathy type δ-ferrite depending on the cooling rate. In this study, the solidification behavior of CASSs (304L and 316L grades) was studied using ThermoCalc software in order to determine the solidification sequence and final microstructure during cooling. Theoretical findings were supported by the microstructural examinations. For the mechanical characterization, not only hardness measurements but also tribological studies were carried out under dry sliding conditions and worn surfaces were examined by microscopy and 3D profilometric analysis. Results were discussed according to the type and amount of microstructural features.
Źródło:
Archives of Foundry Engineering; 2017, 17, 3; 163-167
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
www-Based Boolean Function Minimization
Autorzy:
Tomaszewski, S. P.
Celik, I. U.
Antoniou, G. E.
Powiązania:
https://bibliotekanauki.pl/articles/908086.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
informatyka
digital logic
logic design
Boolean function
Boolean minimization
Quine-McCluskey metod
Opis:
In this paper a Boolean minimization algorithm is considered and implemented as an applet in Java. The application is based on the Quine-McCluskey simplification technique with some modifications. The given application can be accessed on line since it is posted on the World Wide Web (WWW), with up to four variables, at the URL http://www.csam.montclair.edu/~antoniou/bs. After extensive testing, the performance of the algorithm has been found to be excellent. The proposed application is a useful aid for students and professors in the fields of electrical and computer engineering and computer science as well as a valuable tool for digital designers.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2003, 13, 4; 577-583
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Immunological harmony: the role of magnesium in the development of euthyroid Hashimoto’s thyroiditis
Autorzy:
Celik, E.
Celik, M.
Bulbul, B.Y.
Andac, B.
Okur, M.
Colak, S.Y.
Yekdes, A.C.
Powiązania:
https://bibliotekanauki.pl/articles/53363878.pdf
Data publikacji:
2024
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Opis:
Magnesium is a trace element that is closely linked to thyroid function and autoimmune thyroiditis. Numerous chronic disorders are also linked to low serum magnesium levels; however, it is unclear how its level relates to the development of autoimmune thyroiditis. In the present study, we evaluated the relationship between Hashimoto’s thyroiditis (HT) and serum magnesium levels in 104 patients: 52 with low and 52 with normal serum magnesium levels. Patient records were retrospectively evaluated and the demographic data, serum levels of thyroid-stimulating hormone, anti-thyroid peroxidase antibody (TPOAb), anti-thyroglobulin antibody (TGAb) and serum magnesium levels were recorded. Patients with low magnesium levels were found to have higher levels of TPOAb, TGAb and radiological evidence of HT when compared to those with normal magnesium levels (P = 0.001, P = 0.007, and P = 0.001, respectively). In logistic regression analysis, ultrasonographic HT findings were found to be significantly more common in the magnesium deficient group (P = 0.001). The serum magnesium level of 0.72 mmol L-1 was determined to be the appropriate cut-off point for the presence of HT ultrasonographic findings with 68.9% sensitivity and 64.4% specificity. As a result, in the present study, low serum magnesium levels were found to be associated with significantly higher incidence of ultrasonographic findings of HT, which may suggest that adequate magnesium supplementation may be an independent protective factor against Hashimoto’s Thyroiditis.
Źródło:
Journal of Elementology; 2024, 29, 2; 367-378
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variation of biochemical content in the almonds of the endemic Argan tree (Argania spinosa (L.) Skeels) populations in Morocco
Autorzy:
Ayan, S.
Abdaloğlu, G.
Laaribya, S.
Turfan, N.
Çelik, E.N.Y.
Ouhaddou, H.
Alaoui, A.
Powiązania:
https://bibliotekanauki.pl/articles/29430778.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Źródło:
Dendrobiology; 2023, 90; 47-57
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of contact characteristics of a patient-specific artificial dysplastic hip joint
Autorzy:
Mutlu, I.
Ugur, L.
Celik, T.
Buluc, L.
Muezzinoglu, U. S.
Kisioglu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/306768.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanics
pressure
hip dysplasia
biomechanika
ciśnienie
biodro
Opis:
This study addresses the results of the experimental measurements for the contact surface areas and contact pressure distributions of a dysplastic hip joint. The hip joint consists of pelvis, proximal femur and artificial cartilages for both acetabulum and femoral head. The dysplastic hip joint is modeled in three dimensional (3D) form using the computerized tomography (CT) images obtained in vivo of an adult female patient. The modeled hip joint components are manufactured as a non-natural dysplastic hip joint using different materials and manufacturing processes. The dysplastic hip joint produced is subjected to compression forces experimentally to measure the contact surface area and contact pressure distributions between the femoral head and acetabulum using the pressure sensitive Fuji film. Different types of specific fixtures and molds are designed and manufactured to produce the dysplastic hip joint components and perform the experimental studies. The measured results using a non-natural dysplastic hip joint are compared with relevant results reported in current literature considering the peak and mean contact pressure values. Therefore, the obtained results showed that the non-natural dysplastic hip models can be generated and replaced to determine the contact characteristics for an elusive cadaveric model. In conclusion, the artificial models might be useful to understand the contact pressure distributions and potential changes in surface pressure contours and their effects on the stress distributions.
Źródło:
Acta of Bioengineering and Biomechanics; 2014, 16, 2; 111-120
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Gd₂O₂SO₄:Pr⁺³ Scintillation Material Produced by Sol-Gel Process for Digital Imaging System
Autorzy:
Aritman, I.
Yildirim, S.
Kisa, A.
Guleryuz, L.
Yurddaskal, M.
Dikici, T.
Celik, E.
Powiązania:
https://bibliotekanauki.pl/articles/1033327.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Hx
Opis:
Scintillation materials are widely used in digital X-ray imaging applications, radiotherapy applications coupled with suitable photoreceptors. Gd₂O₂SO₄ (GOS) scintillator doped with trivalent praseodymium (Pr⁺³) presented high X-ray absorption properties and good spectral compatibility which were utilized extensively for imaging system of X-ray microscopy, soft X-ray phosphor screen for water window. In this study, GOS:0.01Pr⁺³ scintillation material was synthesized by unique sol-gel process which was not previously applied and its characterization properties were investigated. Structure and luminescence properties of GOS:Pr⁺³ were optimized by utilizing X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and luminescence spectroscopy.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 106-108
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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