Thermo-Electrical Properties in Pb-Sb Hypereutectic Alloy

M. ¸Sahin,E. Çadırlı,Y. Sürme,D. Özkır 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.3

Pb-17 wt% Sb hypereutectic alloy was directionally solidified upward with three different growth rates (8μm/s, 18 μm/s, 42 μm/s, 166 μm/s and 497 μm/s) at a constant temperature gradient (3.6 K/mm) in the Bridgman-type growth apparatus. The dependence of characteristic microstructure parameters such as primary dendrite arm spacing (λ1) and secondary dendrite arm spacing (λ2) on the growth rate (V) were determined by using a linear regression analysis. Variations of electrical resistivity (ρ) for cast samples for temperatures in the range of 300-550 K were measured by using a standard dc four-point probe technique. The variations of thermal conductivity with temperature for the same alloys were determined from the WiedemannFranz and SmithPalmer equations by using the measured values of electrical resistivity. The enthalpy of fusion for the same alloys were determined by means of a differential scanning calorimeter from a heating trace during the transformation from solid to liquid. The corrosion resistance was analyzed by Tafel extrapolation and linear polarization resistance methods conducted in a 5% sodium chloride solution in contact with air maintained at room temperature. Effects of the growth rate on the electrical resistivity and corrosion resistance were also investigated.

Cell Viability of Normal Human Skin Fibroblast and Fibroblasts Derived from Granulation Tissue: Effects of Nutraceuticals

Borawska, M.H.,Czechowska, S.K.,Markiewicz, R.,Hayirli, A.,Olszewska, E.,Kazim Sahin, D.V.M The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.2

The effects of lycopene, genistein, and epigallocatechin-3-gallate (EGCG) on cell viability were tested in vitro using a normal human skin fibroblast (NHSF) cell line (CRL-1474) and granulation tissue fibroblasts (GTFs) obtained from a patient with middle ear cholesteatoma. Cell cultures were added with lycopene (1, 5, and $10\;{\mu}M$), genistein (1, 5, 10, 25, and $50\;{\mu}M$), and EGCG (1, 5, 10, 25, and $50\;{\mu}M$) and their respective control cultures were established by adding 5 mL/L tetrahydrofuran (THF), 5 mL/L dimethyl sulfoxide (DMSO), and 5 mL/L DMSO. A colorimetric assay was employed for determining cell viability using thiazolyl blue tetrazolium bromide. Cell viability was expressed as a percentage of the control. Data were analyzed using two-way analysis of variance separately for each compound. Lycopene addition decreased viability of NHSFs and GTFs compared with THF addition (64.1%, 60.5%, and 100%, respectively, P < .0001). Genistein addition also increased viability of both NHSFs and GTFs compared with DMSO addition (P < .02). Increasing EGCG concentration tended to cause a linear increase in viability of NHSFs but did not alter viability of GTFs (P < .10). Our data suggest that genistein and EGCG but not lycopene could help maintaining or improving skin health through enhancing viability of skin fibroblasts.

Effects of Dietary Lycopene and Vitamin E on Egg Production, Antioxidant Status and Cholesterol Levels in Japanese Quail

N. Sahin,K. Sahin,M. Onderci,M. Karatepe,M. O. Smith,O. Kucuk 아세아·태평양축산학회 2006 Animal Bioscience Vol.19 No.2

Japanese Quails were used to evaluate the effects of dietary supplementation with vitamin E (dl-a-tocopheryl-acetate), lycopene, and their combination on egg production, egg quality, concentrations of malondialdehyde (MDA), vitamin E, A and cholesterol in serum and egg yolk. Quails (n = 120; 55 d old) were divided into four groups (n = 30/group) and fed a basal diet or the basal diet supplemented with lycopene (100 mg/kg diet), vitamin E (250 mg dl-慣-tocopheryl-acetate/kg diet) or a combination of lycopene and vitamin E (100 mg/kg lycopene plus 250 mg dl-慣-tocopheryl-acetate/kg diet). Vitamin E and lycopene did not affect (p>0.05) body weight, feed intake or egg weight. Egg production and Haugh unit were greater (p<0.05) in each supplemental group compared with the control group (p<0.05). Serum and liver MDA levels were decreased in supplemented groups compared with the control group. Separately or as a combination, supplemental lycopene and vitamin E increased serum and egg yolk vitamin E and A but decreased cholesterol concentrations (p<0.05). In general, when a significant effect was found for a parameter, the magnitude of the responses to vitamin and lycopene supplements was greatest with the combination of the lycopene and vitamin E, rather than that observed with each supplement separately. Results of the present study indicate that supplementing with a combination of dietary lycopene and vitamin E reduced serum and yolk cholesterol concentrations and improved antioxidant status.

Cell Viability of Normal Human Skin Fibroblast and Fibroblasts Derived from Granulation Tissue: Effects of Nutraceuticals

M.H. Borawska,S.K. Czechowska,R. Markiewicz,A. Hayirli,E. Olszewska,K. Sahin 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.2

The effects of lycopene, genistein, and epigallocatechin-3-gallate (EGCG) on cell viability were tested in vitro using a normal human skin fibroblast (NHSF) cell line (CRL-1474) and granulation tissue fibroblasts (GTFs) obtained from a patient with middle ear cholesteatoma. Cell cultures were added with lycopene (1, 5, and 10 μM), genistein (1, 5, 10, 25, and 50 μM), and EGCG (1, 5, 10, 25, and 50 μM) and their respective control cultures were established by adding 5 mL/L tetrahydrofuran (THF), 5 mL/L dimethyl sulfoxide (DMSO), and 5 mL/L DMSO. A colorimetric assay was employed for determining cell viability using thiazolyl blue tetrazolium bromide. Cell viability was expressed as a percentage of the control. Data were analyzed using two-way analysis of variance separately for each compound. Lycopene addition decreased viability of NHSFs and GTFs compared with THF addition (64.1%, 60.5%, and 100%, respectively, P < .0001). Genistein addition also increased viability of both NHSFs and GTFs compared with DMSO addition (P < .02). Increasing EGCG concentration tended to cause a linear increase in viability of NHSFs but did not alter viability of GTFs (P < .10). Our data suggest that genistein and EGCG but not lycopene could help maintaining or improving skin health through enhancing viability of skin fibroblasts.

Is there a relationship between beginning time and efficiency of octreotide in the treatment of experimental acute pancreatitis?

M. Ertugrul Kafali,Mehmet Gul,Husnu Alptekin,Mustafa Sahin,Hatice Toy,Mehmet Akoz 대한외과학회 2012 Annals of Surgical Treatment and Research(ASRT) Vol.82 No.5

Purpose: The efficacy of octreotide in the treatment of acute pancreatitis is controversial. Octreotide treatment for acute pancreatitis often shows poor correlation between results obtained in experimental studies and results of clinical trials. In a clinical setting, there is always a delay between the onset of the disease and initiation of the octreotide treatment. The aim of this study is to investigate the relationship between the beginning of treatment and alteration in effectiveness of octreotide. Methods: Acute pancreatitis was induced by pancreatic duct ligation in 50 rats. The rats were randomly divided into five groups. Octreotide was not used in group 1 (control group). Only single dose (4 ㎍/㎏) octreotide was administered subcutaneously to rats in group 2, having induced pancreatitis. Octreotide treatment was begun at different times (8th, 24th, 48th hour) in three other groups and continued treatment at a dosage of 4 μg/kg t.i.d. The animals were sacrificed at the end of the 72nd hour and blood and tissue samples were collected. Results: Leukocyte count and plasma amylase values were less in groups 2 and 3. Hemorrhagic focuses were encountered less at pancreas tissues in group 3. Pancreatic necrosis and alveolar capillary basal membrane damage were lower in groups 3 and 4. No difference was found in fasting blood glucose, calcium and hematocrit. Conclusion: Octreotide had benefical effects in acute pancreatitis when octreotide treatment was begun in the first 24 hours.

A Comparative Study of South Korea and Turkey : Attitudes, Beliefs, and Creative Student Oriented Teaching Practices of Middle School Mathematics Teachers

( Corlu M Sencer ),( Erdogan Niyazi ),( Sahin Alpaslan ) 한국수학교육학회 2011 수학교육 학술지 Vol.2011 No.-

Teachers`attitudes and beliefs are related to teaching practices and are dependent upon their teaching domain. The present study compares conceptual models of creative student oriented teaching practices of mathematics teachers in two OECD countries, South Korea and Turkey to provide an insight for teacher educators and policy makers. Teaching and Learning International Survey (TALIS) 2008 data are used to test the fit of a path analysis model with a subsample of 1337 middle school mathematics teachers (NKorea= 562; NTurkey=775). The study showed that Turkish teachers were younger and less experienced, whereas Korean teachers were better educated. Despite the statistical differences in attitudes, beliefs and practices between countries, it was found that the teaching practices of mathematics teachers in both countries were more complex than to be explained only through attitudes and beliefs.

Cognitive UWB-OFDM: Pushing Ultra-Wideband Beyond Its Limit via Opportunistic Spectrum Usage

H. Arslan,M. E. Sahin 한국통신학회 2006 Journal of communications and networks Vol.8 No.2

Synthesis and Antinociceptive Activity of (5-Chloro-2(3H)-Benzoxazolon-3-yl) Propanamide Derivatives

Onkol, Tijen,Sahin, M.Fethi,Yidirim, Engin,Erol, Kevser,Ito, Shigero The Pharmaceutical Society of Korea 2004 Archives of Pharmacal Research Vol.27 No.11

In this study, (5-chloro-2(3H)-benzoxazolon-3-yl)propanamide derivatives were synthesized. The chemical structures of the compounds were elucidated by their IR and $^1H-NMR$ spectral data and microanalysis. The compounds were tested for anti nociceptive activity by using the tail clip, tail flick, hot plate, and writhing methods. The varying levels of anti nociceptive activity of the compounds were compared with those of dipyrone and aspirin. Among these compounds, compound 5e, 5g, and 5h have been found to be significantly more active than the others and the standards in all the tests.

New family of graphene-based organic semiconductors: An investigation of photon-induced electronic structure manipulation in half-fluorinated graphene

Walter, Andrew L.,Sahin, Hasan,Kang, Jun,Jeon, Ki-Joon,Bostwick, Aaron,Horzum, Seyda,Moreschini, Luca,Chang, Young Jun,Peeters, Francois M.,Horn, Karsten,Rotenberg, Eli American Physical Society 2016 Physical Review B Vol.93 No.7

<P>The application of graphene to electronic and optoelectronic devices is limited by the absence of reliable semiconducting variants of this material. A promising candidate in this respect is graphene oxide, with a band gap on the order of similar to 5 eV, however, this has a finite density of states at the Fermi level. Here, we examine the electronic structure of three variants of half-fluorinated carbon on Sic(0001), i.e., the (6 root 3 x 6 root 3) R30 degrees C/SiC 'buffer layer,' graphene on this (6 root 3 x 6 root 3) R30 degrees C/SiC buffer layer, and graphene decoupled from the SiC substrate by hydrogen intercalation. Using angle-resolved photoemission, core level photoemission, and x-ray absorption, we show that the electronic, chemical, and physical structure of all three variants is remarkably similar, exhibiting a large band gap and a vanishing density of states at the Fermi level. These results are explained in terms of first-principles calculations. This material thus appears very suitable for applications, even more so since it is prepared on a processing-friendly substrate. We also investigate two separate UV photon-induced modifications of the electronic structure that transform the insulating samples (6.2-eV band gap) into semiconducting (similar to 2.5-eV band gap) and metallic regions, respectively.</P>

Comparison of In situ Dry Matter Degradation with In vitro Gas Production of Oak Leaves Supplemented with or without Polyethylene Glycol (PEG)

Ozkan, C. Ozgur,Sahin, M. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.8

Dry matter (DM) degradation of leaves from Quercus cercis, Quercus libari, Quercus branti, and Quercus coccifera was determined using two different techniques: (i) in vitro gas production and (ii) the nylon bag degradability technique. In vitro gas production in the presence or absence of PEG and in situ DM disappearance were measured at 3, 6, 12, 24, 48, 72 and 96 h. In situ and in vitro DM degradation kinetics were described using the equation y = a+b ($1-e^{-ct}$). At all incubation times leaves from Quercus branti incubated with or without PEG gave significantly higher gas production than the other oak leaves except for 3 and 6 h incubation when leaves from Quercus branti without PEG supplementation only gave higher gas production than Quercus cercis and Quercus coccifera. At all incubation times except at 3, 6 and 12 h the DM disappearance from Quercus branti was significantly higher than the other species. Generally, PEG supplementation considerably increased the gas production at all incubation times and estimated parameters such as gas production rate ($c_{gas}$), gas production (ml) from the quickly soluble fraction ($a_{gas}$), gas production (b) from the insoluble fraction, potential gas production (a+b). However, all oak leaves did not give the same response to the PEG supplementation. Although the increase in gas production at 96 h incubation time was 8.9 ml for Quercus libari the increase was 5.5 ml for Quercus coccifera. It was concluded that except at early incubation times the relationships between the two methodologies seem to be sufficiently strong to predict degradability parameters from gas production parameters obtained in the presence or absence of PEG.