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ZnO thin films are prepared on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) at room temperature. Optical parameters such as optical transmittance, reflectance, band tail, dielectric coefficient, refractive index, energy band gap have been studied, discussed and correlated to the changes with film thickness. Kramers-Kronig and dispersion relations were employed to determine the complex refractive index and dielectric constants using reflection data in the ultraviolet-visible-near infrared regions. Films with optical transmittance above 90% in the visible range were prepared at pressure of 6.5 × 10−4 Torr. XRD analysis revealed that all films had a strong ZnO (0 0 2) peak, indicating c-axis orientation. The crystal grain size increased from 14.97 nm to 22.53 nm as the film thickness increased from 139 nm to 427 nm, however no significant change was observed in interplanar distance and crystal lattice constant. Optical energy gap decreased from 3.21 eV to 3.19 eV with increasing the thickness. The transmission in UV region decreased with the increase of film thickness. The refractive index, Urbach tail and real part of complex dielectric constant decreased as the film thickness increased. Oscillator energy of as-deposited films increased from 3.49 eV to 4.78 eV as the thickness increased. 相似文献
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Ebru Begeç Sıtkı Eker Süleyman Bozdemir 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(8):1408-1413
Pressure-induced phase transition in MgS is studied using a constant pressure ab initio molecular dynamics method, and a solid evidence of existence of its high-pressure phase is provided. As predicted by total energy calculations, MgS undergoes a structural phase transformation from the rocksalt structure to a CsCl-type structure under hydrostatic pressure. The transformation mechanism is characterized, and two intermediate phases having P4/nmm and P21/m symmetries for the rocksalt-to-CsCl-type phase transformation of MgS are proposed, which is different from the previously proposed mechanisms. We also study this phase transition using the total energy calculations. Our predicted transition parameters and bulk properties are in good agreement with the earlier first principle simulations. 相似文献
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Baris Kucukkaraduman Ekin Gokce Cicek Muhammad Waqas Akbar Secil Demirkol Canli Burcak Vural Ali Osmay Gure 《Molecules (Basel, Switzerland)》2021,26(19)
Numerous natural products exhibit antiproliferative activity against cancer cells by modulating various biological pathways. In this study, we investigated the potential use of eight natural compounds (apigenin, curcumin, epigallocatechin gallate, fisetin, forskolin, procyanidin B2, resveratrol, urolithin A) and two repurposed agents (fulvestrant and metformin) as chemotherapy enhancers and mesenchymal-to-epithelial (MET) inducers of cancer cells. Screening of these compounds in various colon, breast, and pancreatic cancer cell lines revealed anti-cancer activity for all compounds, with curcumin being the most effective among these in all cell lines. Although some of the natural products were able to induce MET in some cancer cell lines, the MET induction was not related to increased synergy with either 5-FU, irinotecan, gemcitabine, or gefitinib. When synergy was observed, for example with curcumin and irinotecan, this was unrelated to MET induction, as assessed by changes in E-cadherin and vimentin expression. Our results show that MET induction is compound and cell line specific, and that MET is not necessarily related to enhanced chemosensitivity. 相似文献
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Aylin Altınışık Ebru Bozacı Emine Akar Yoldas Seki Kadir Yurdakoc Asli Demir Esen Özdogan 《Cellulose (London, England)》2013,20(6):3111-3121
In order to provide antimicrobial activity to cotton, cotton fabrics were treated by montmorillonite (KSF), montmorillonite–dihydroxy ethylene urea (KSF–MDEU), KSF–chitosan (CS) and KSF–CS–MDEU solutions containing 12.5, 25 and 50 ppm silver ion. The effect of modification on the antibacterial activity of cotton fabrics was also evaluated after 10 cycles of washings. MDEU exhibited better antimicrobial activities after washing process. By using 25 ppm silver, KSF and CS modification solution, good performance in terms of antibacterial activity was obtained. The addition of CS and MDEU increased the whiteness index values of cotton fabrics treated with KSF containing different silver concentrations. The characterization of modified cotton samples was done by Fourier transform infrared spectroscopy, X-ray diffraction analysis, inductively coupled plasma-mass spectroscopy, scanning electron microscopy and thermogravimetric analysis. 相似文献
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Demirbilek ME Demirbilek M Karahaliloğlu Z Erdal E Vural T Yalçın E Sağlam N Denkbaş EB 《Applied biochemistry and biotechnology》2011,164(6):780-792
Oxidative stress may produce high level of reactive oxygen species (ROS) following cell exposure to endogenous and exogenous
factors. Recent experiments implicate oxidative stress as playing an essential role in cytotoxicity of many materials. The
aim of this study was to measure intracellular malondialdehyde (MDA), advanced oxidation protein product (AOPP) levels, and
superoxide dismutase (SOD) activities of L929 fibroblasts cultured on PDLLA, polyethylene glycol (PEG), or ethylenediamine
(EDA) grafted PDLLA by plasma polymerization method. Cell proliferation on these scaffolds was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl
tetrazolium bromide assay. The study showed that MDA, AOPP levels, and SOD activities in L929 fibroblast cells cultured on
all scaffolds were significantly different compared to the control group and each other. The highest MDA (0.42 ± 0.76 nmol/mg
protein), AOPP (14.99 ± 4.67 nmol/mg protein) levels, and SOD activities (7.49 ± 3.74 U/mg protein) were observed in cells
cultured on non-modified scaffolds; meanwhile, the most cell proliferation was obtained in EDA-modified scaffolds (MDA 0.15 ± 0.14 nmol/mg
protein, AOPP 13.12 ± 3.86 nmol/mg protein, SOD 4.82 ± 2.64 U/mg protein). According to our finding, EDA- or PEG-modified
scaffolds are potentially useful as suitable biomaterials in tissue engineering. 相似文献