Genç, Ayten

Article | 2009 | Turkish Journal of Engineering and Environmental Sciences33 ( 1 ) , pp.73 - 81

The membrane potentials for asymmetric membranes where fixed charges varied linearly with position were evaluated from the numerical solutions of Nernst-Planck flux and Donnan potential equations. The evaluated membrane potentials were compared with the results obtained from the conventional TMS theory where the fixed charge concentration in the membrane was assumed to be uniform. In the comparison, the number of fixed charges was kept constant by defining an average for the fixed charge concentration. The numerical results showed that the membrane potential increased in magnitude when the distributions of fixed charges at the membr . . .ane-solution interfaces were unequal. In addition, the deviation from TMS theory increased more as the charge difference at the interfaces increased. © TÜBİTAK Daha fazlası Daha az

Çoruh, Nursen | Özdoğan, Nizamettin

Article | 2017 | Turkish Journal of Biology41 ( 1 ) , pp.195 - 212

Rosa heckeliana, as one of the wild-growing species of the family Rosacea, has a wide use in the folk medicine; however, scientifically there is very little known about it. Our objective was to examine the antioxidative and antiproliferative properties of Rosa heckeliana root extract and its phenolics. The phenolic constituents, namely catechin, caffeic acid, and ellagic acid, were obtained by the methods of extraction, fractionation, and purification through column chromatography. The DPPH and ABTS radical scavenging assays and total flavonoid content analysis were employed as the current antioxidant methods over the crude extract . . .and fractionated parts. Among the extracts/fractions, the ethyl acetate fraction exhibited the highest amount of flavonoid content (4.58 ± 0.018 µg CE/ mg of extract). The ethyl acetate fraction also displayed high antioxidative properties for DPPH (EC50 value: 2.78 ± 0.01 µg/mL) and ABTS scavenging capacities (586 ± 6.64 µM trolox as TEAC value). Additionally, the antiproliferative properties of the crude extract and the ethyl acetate fraction and its isolated constituents were evaluated for two breast cancer cell lines (MCF-7 and MDA-MB-231) using the XTT method. Acetate fraction over the cells of MCF-7 and MDA-MB-231 resulted in ED50 values of 61.18 ± 0.99 µg/mL and 62.54 ± 2.01 µg/mL, respectively. The isolated phenolic constituents were twice as effective as the ethyl acetate fraction on both MCF-7 and MDA-MB-231 cells. Rosa heckeliana, as one of the wild-growing species of the family Rosacea, has a wide use in the folk medicine; however, scientifically there is very little known about it. Our objective was to examine the antioxidative and antiproliferative properties of Rosa heckeliana root extract and its phenolics. The phenolic constituents, namely catechin, caffeic acid, and ellagic acid, were obtained by the methods of extraction, fractionation, and purification through column chromatography. The DPPH and ABTS radical scavenging assays and total flavonoid content analysis were employed as the current antioxidant methods over the crude extract and fractionated parts. Among the extracts/fractions, the ethyl acetate fraction exhibited the highest amount of flavonoid content (4.58 ± 0.018 µg CE/ mg of extract). The ethyl acetate fraction also displayed high antioxidative properties for DPPH (EC50 value: 2.78 ± 0.01 µg/mL) and ABTS scavenging capacities (586 ± 6.64 µM trolox as TEAC value). Additionally, the antiproliferative properties of the crude extract and the ethyl acetate fraction and its isolated constituents were evaluated for two breast cancer cell lines (MCF-7 and MDA-MB-231) using the XTT method. Acetate fraction over the cells of MCF-7 and MDA-MB-231 resulted in ED50 values of 61.18 ± 0.99 µg/mL and 62.54 ± 2.01 µg/mL, respectively. The isolated phenolic constituents were twice as effective as the ethyl acetate fraction on both MCF-7 and MDA-MB-231 cells Daha fazlası Daha az

Erdoğan, Zeynep | Zeydan, Özgür | Sert, Havva

Article | 2008 | İstanbul Üniversitesi Florence Nightingale Hemşirelik Yüksekokulu Dergisi16 ( 61 ) , pp.71 - 76

Dünyanın iklimi jeolojik tarih boyunca birçok kez doğal olarak değişmiştir. Fakat, endüstri devriminden sonra fosil yakıtlarından kaynaklanan emisyonlar ve diğer sentetik sera gazlarının emisyonlarıyla artan sera etkisi nedeniyle sıcaklık kayıtlarında yükseliş trendi mevcuttur. Sera etkisi atmosferin ısı kapasitesini değiştirerek sıcaklık ve yağış anormalliklerine ve en sonunda da iklim değişikliğine neden olur. iklim değişiklinin etkileri ekosistemlerde, sosyal ve ekonomik yaşamda ve arazi kullanımıyla sınırlı olmayıp ayrıca, doğrudan ve dolaylı olarak insan sağlığı üzerine etkileri de vardır. Sıcak dalgalarına bağlı ölümler, solun . . .um ve dolaşım sistemi hastalıkları ve infeksiyon hastalıkları iklim değişikliği sonucunda ortaya çıkan sağlık sorunlarıdır. Earth's climate has changed naturally many times throughout the geological history. However, after the industrial revolution there exists a rising trend in temperature records due to increasing greenhouse effect, which is resulted from fossil fuel emissions and other synthetic greenhouse gasses emissions. Greenhouse effect changes heat capacity of atmosphere that causes temperature and precipitation anomalies and ultimately climate change. The effects of climate change will be seen in ecosystems, in social and economical life and in land use. Moreover, there are direct and indirect health effects of climate change on humans. Mortality depending on heat waves, respiratory and cardiovascular disease and infectious disease are the health problem resulted from climate change Daha fazlası Daha az