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Theoretical Study on the Point Defects in N-Doped Anatase TiO2
Song-You Wang,Fei Pei,Song Wu,Gang Wang,Ming Xu,Liang-Yao Chen,Yu Jia 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.4
In this work, first-principles calculations for the electronic and the optical properties of titanium dioxide (TiO2) with point defects are performed by using a plane wave pseudopotential method in the framework of the density functional theory and the generalized gradient approximation. The point defects, substitutional and interstitial nitrogen, in anatase TiO2 are investigated to understand the origin of the visible-light sensitivity of nitrogen (N)-doped TiO2. The results show that bands originating from substitutional N 2p states appear above the top of the valence band. These states tend to be delocalized and to mix with the valence band as the nitrogen concentration is increased. The optical absorption in the range between 400 and 700 nm is enhanced by the substitutional N impurities. The eect of interstitial N on the electronic and the optical properties of TiO2 depends on the interaction between the nitrogen dopants and the surrounding oxygen. The bonding between N and O introduces a series of localized occupied states under and above the upper valence band, and the electron transitions from these states improve the visible-light absorption of TiO2.
Song-You Wang,Zhao-Hua Geng,Gang Wang,Song Wu,Liang-Yao Chen,Yu Jia 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.4
In this paper, the electronic and the optical properties of oxides for group-IV elements in an inverse Ag2O structure, including Si, Ge, and Sn, and their ternary alloys, were studied with the density function theory of first principles. The results show that they have a high-density phase and a high dielectric constant. Moreover, the lattice constants of Si0.5Ge0.5O2 and SiO2 are really close to those of Si(100) surfaces, suggesting the possibility of forming a defect-free superlattice. With changing element, the calculated results show that the lattice constants of the ternary alloys tend to be bigger while the energy gaps show a different trend. The optical properties of these compounds as functions of physical quantities, such as the density of states, the complex dielectric function,and the static dielectric constant, are given to support the potential applications of the compounds in the future.
First-principles Study on the Electronic Structures and the Optical Properties of Hg1−xCdxTe
Song-You Wang,Gang Wang,Song Wu,Zhao-Hua Geng,Liang-Yao Chen,Yu Jia 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.4
The electronic structures and the optical properties of the direct-band-gap infrared alloy Hg1−xCdxTe (x = 0.250, 0.375, 0.500, 0.625, 0.875, and 1.000) were obtained using the local spin density approximation (LSDA) in the density functional theory (DFT). The calculated lattice constants are in agreement with these calculated using Vergard’s law and the band structures of these alloys are similar. The three peaks of the imaginary part in the dielectric function reveal that the conduction bands lift with increasing x. The calculated static dielectric constants of these alloys were shown to behave as a parabolic function. The results for the loss functions and effective electronic densities show that few electrons take part in the interband transitions.
Wang, Chang-Dong,Yuan, Cheng-Fu,Bu, You-Quan,Wu, Xiang-Mei,Wan, Jin-Yuan,Zhang, Li,Hu, Ning,Liu, Xian-Jun,Zu, Yong,Liu, Ge-Li,Song, Fang-Zhou Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.2
Fangchinoline (Fan) inhibits cell proliferation and induces apoptosis in several cancer cell lines. The effects of Fan on cell growth and proliferation in breast cancer cells remain to be elucidated. Here, we show that Fan inhibited cell proliferation in the MDA-MB-231 breast cancer cell line through suppression of the AKT/Gsk-3beta/cyclin D1 signaling pathway. Furthermore, Fan induced apoptosis by increasing the expression of Bax (relative to Bcl-2), active caspase 3 and cytochrome-c. Fan significantly inhibited cell proliferation of MDA-MB-231 cells in a concentration and time dependent manner as determined by MTT assay. Flow cytometry analysis demonstrated that Fan treatment of MDA-MB-231 cells resulted in cell cycle arrest at the G1 phase, which correlated with apparent downregulation of both mRNA and protein levels of both PCNA and cyclin D1. Further analysis demonstrated that Fan decreased the phosphorylation of AKT and GSK-3beta. In addition, Fan up-regulated active caspase3, cytochrome-c protein levels and the ratio of Bax/Bcl-2, accompanied by apoptosis. Taken together, these results suggest that Fan is a potential natural product for the treatment of breast cancer.
Song, Kwan-Jeong,Beak, Dong-Chul,Kim, You-Wang,Kim, Young-Geol,Lee, Min-Seok,Lee, Sam-Pin,Kim, Chan-Shick The Korean Society of Food Science and Nutrition 2010 Preventive Nutrition and Food Science Vol.15 No.3
Caffeine and catechins from the Yabukita, Yutakamidori, Saemidori, Okumidori, and Fushun varieties of tea leaves picked during different harvesting seasons from April to October were evaluated using HPLC. Total content of catechins increased greatly with the later harvesting time of tea leaves (i.e., picking the leaves in September versus in April) and decreased slightly after September. Yabukita tea leaves picked in August contained 43.1 mg% catechins including EGC, EC, ECG, and EGCG, with the ECGC levels constituting greater than 50% of those four compounds. Yutakamidori and Okumidori varieties picked in September contained the highest catechin values, at 43.6 mg% and 31.0 mg%, respectively. Fushun and Saemidori varieties contained lower catechin concentrations of 14.5 mg% (July) and 11.7 mg% (August) compared to other varieties. The EGCG levels gradually decreased in the late harvesting season, while levels of the other catechins, EC, EGC, and ECG, gradually increased. All varieties of green tea showed a gradual decrease in caffeine content toward the end of our harvesting efforts in October, with levels of 58~68 mg% in April and 28~57 mg% in October. Yabukita, Saemidori, and Okumidori varieties reached their highest caffeine levels in late spring/early summer, with Yabukita and Okumidori varieties reaching a high of 73.4% and 63.5% caffeine, respectively, in May, and Saemidori at 64.0% in June. In particular, Fushun still contained high caffeine of 66.8 mg% (September) during the late harvesting season.
Zhang, Song,Huang, Wei-Bin,Wu, Li,Wang, Lai-You,Ye, Lian-Bao,Feng, Bing-Hong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.10
$N^1$-(2, 5-dimethoxyphenyl)-$N^8$-hydroxyoctanediamide (N25) is a novel SAHA cap derivative of HDACi, with a patent (No. CN 103159646). This invention is a hydroxamic acid compound with a structural formula of $RNHCO(CH_2)6CONHOH$ (wherein R=2, 5dimethoxyaniline), a pharmaceutically acceptable salt which is soluble. In the present study, we investigated the effects of N25 with regard to drug distribution and molecular docking, and anti-proliferation, apoptosis, cell cycling, and $LD_{50}$. First, we designed a molecular approach for modeling selected SAHA derivatives based on available structural information regarding human HDAC8 in complex with SAHA (PDB code 1T69). N25 was found to be stabilized by direct interaction with the HDAC8. Anti-proliferative activity was observed in human glioma U251, U87, T98G cells and human lung cancer H460, A549, H1299 cells at moderate concentrations ($0.5-30{\mu}M$). Compared with SAHA, N25 displayed an increased antitumor activity in U251 and H460 cells. We further analyzed cell death mechanisms activated by N25 in U251 and H460 cells. N25 significantly increased acetylation of Histone 3 and inhibited HDAC4. On RT-PCR analysis, N25 increased the mRNA levels of p21, however, decreased the levels of p53. These resulted in promotion of apoptosis, inducing G0/G1 arrest in U251 cells and G2/M arrest in H460 cells in a time-dependent and dose-dependent manner. In addition, N25 was able to distribute to brain tissue through the blood-brain barrier of mice ($LD_{50}$: 240.840mg/kg). In conclusion, our findings demonstrate that N25 will provide an invaluable tool to investigate the molecular mechanism with potential chemotherapeutic value in several malignancies, especially human glioma.
Zhang, You-Gai,Shi, Jian-Xiang,Song, Chun-Hua,Wang, Peng,Dai, Li-Ping,Zhang, Jian-Ying,Shi, Jia-Chen Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.4
Meta-analyses have shown that microRNA polymorphisms have variable effects in different population. Yet, no meta-analysis investigated the association of two common polymorphisms of miRNA, mir-499 rs3746444 polymorphism and mir-149 rs2292832 polymorphism, with cancer risk in the Chinese population. We searched the PubMed, Web of Knowledge, MEDLINE, CNKI databases, as well as Cochrane library, updated on December 31, 2012 for assays regarding cancer risk association with these two common polymorphisms in the present meta-analysis. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to explore the strength of associations. The results showed that rs3746444 polymorphism was associated with increased cancer risk (dominant model: GG/AG vs. AA: OR = 1.43, 95% CI: 1.14-1.80; recessive model: GG vs. AG/AA: OR = 1.54, 95% CI: 1.04-2.30; homozygote model: GG vs. AA: OR = 1.69, 95% CI: 1.10-2.60; heterozygote model: AG vs. AA: OR = 1. 35, 95% CI: 1.09-1.67), and rs3746444 was associated with liver cancer in the subgroup of cancer types. For the rs2292832 polymorphism, the results showed no significant risk association in both overall pooled analysis and subgroup of cancer types, smoking status, gender and tea drinking status in the Chinese population. This meta-analysis suggested that the rs3746444 GG genotype is associated with increased cancer risk, especially liver cancer, while the rs2292832 polymorphism showed no association with cancer risk in Chinese.
Jing Li,Song-You Wang,Ming Xu,Shen-Jin Wei,Song Wu,Fei Pei,Liang-Yao Chen,Yu Jia 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.4
Ge2Sb2Te5 (GST) is widely used as an excellent data recording material based on its fast and reversible amorphous-to-crystalline phase transformation that is accompanied by changes in the optical reflectivity and the electrical conductivity. It was demonstrated that GST can be transformed reversibly between the amorphous and the cubic phases, and, under certain conditions, it can be transformed between the cubic and the hexagonal phases as well. Thus, if we can take advantage of the differences in the optical and the electrical properties among the amorphous, the cubic, and the hexagonal states, we could use GST as a multi-state storage material, and its storage density would be improved remarkably. In this study, we investigate the electronic and the optical properties of crystalline GST by using both ab-initio and experimental analyses. The results show that the cubic GST is semi-conductive while the hexagonal GST may exhibit much higher conductivity. The reflectivity contrast of the two crystalline states is above 8 % in the range from 400 nm to 700 nm, indicating a potential for applications of GST in multi-state optical data storage.