214 results on '"Wu, Xiaowen"'
Search Results
2. Apatinib combined with camrelizumab in advanced acral melanoma patients: An open-label, single-arm phase 2 trial.
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Wang, Xuan, Wu, Xiaowen, Yang, Yue, Xu, Weiran, Tian, Hui, Lian, Bin, Chi, Zhihong, Si, Lu, Sheng, Xinan, Kong, Yan, Zhou, Li, Mao, Lili, Li, Siming, Tang, Bixia, Yan, Xieqiao, Bai, Xue, Guo, Jun, and Cui, ChuanLiang
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THERAPEUTIC use of antineoplastic agents , *FOOT diseases , *IMMUNE checkpoint inhibitors , *CLINICAL trials , *MELANOMA , *SKIN tumors , *PROTEIN-tyrosine kinase inhibitors , *TREATMENT effectiveness , *DESCRIPTIVE statistics , *PROTEINURIA , *PATIENT safety , *IMMUNOTHERAPY , *EVALUATION - Abstract
At present, immune monotherapy and combination therapy has not shown satisfactory effects on acral melanoma, and still no standard treatment is available for advanced acral melanoma. Here, a phase II trial was performed to explore the safety and efficacy of apatinib combined with camrelizumab in advanced acral melanoma patients as first-line therapy (NCT03955354). Patients with pathologically confirmed, locally unresectable or metastatic treatment native acral melanoma received 250 mg apatinib once daily and camrelizumab 200 mg once every two weeks intravenously every 28-day cycle. The primary end-point was objective response rate and the secondary end-points were disease control rate, overall survival, progression-free survival and safety. Thirty patients were recruited between January 2015 and January 2022. Among them, 21 (70.0%) had stage IV, and a median tumour burden was 50 mm (range: 11–187). Objective response rate was 24.1%, and 7 of 29 patients had an anti-tumour response, including partial response (n = 5) and complete response (n = 2). Disease control rate was 82.8%, median progression-free survival was 7.39 months (confidence interval: 3.65-9.92), and median overall survival was 13.4 months (confidence interval: 1.9–25.0). Grade 3–4 treatment-related toxicity (grade 3 50.5%; grade 4 3.3%) included transaminase elevations, proteinuria, leukocytopenia, vomiting, diarrhea and drug-induced liver injury. No treatment-related mortality occurred. The mutations of TTN, MUC16, VPS13D, ALPK2 and SCUBE1 showed significant alterations with survival outcome. Apatinib combined with camrelizumab showed manageable safety profile and reasonable anti-tumour activity in advanced acral melanoma patients as first-line therapy. • Acral melanoma. • Safety and efficacy of apatinib combined with camrelizumab as first-line therapy. • The first trial of immunotherapy combi anti-angiogenesis inhibitor in acral melanoma. [ABSTRACT FROM AUTHOR]
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- 2023
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3. Genome-wide DNA methylation profile analysis identifies an individualized predictive signature for melanoma immune response.
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Yan, Junya, Wu, Xiaowen, Zhu, Yanyan, and Cang, Shundong
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DNA methylation , *PROGRAMMED cell death 1 receptors , *TUMOR-infiltrating immune cells , *IMMUNE response , *CD8 antigen , *MELANOMA - Abstract
Purpose: The current evaluation methods for tumor infiltrating lymphocytes (TILs), particularly CD8 + TILs, mainly rely on semiquantitative immunohistochemistry with high variability. We aimed to construct an individualized DNA methylation-based signature for CD8 + TILs (CD8 + MeTIL) that may characterize melanoma immune microenvironment and guide therapeutic selection. Methods: The transcriptome profiles and DNA methylation data of 457 melanoma patients from The Cancer Genome Atlas (TCGA) database were analyzed. Differential methylation analysis between groups with high and low CD8 + TILs was performed to select differentially methylated positions (DMPs) and define CD8 + MeTIL. The prognostic value of CD8 + MeTIL and its predictive value for immunotherapy response were investigated using multiple melanoma cohorts. Results: We successfully constructed the CD8 + MeTIL signature based on four DMPs. The survival analyses showed that higher CD8 + MeTIL score was associated with worse survival outcomes in TCGA-SKCM and GSE144487 cohorts. The ROC curve for the predictive analysis revealed that the survival prediction of CD8 + MeTIL score was superior compared with CD8 + TILs (CIBERSORT) and CD8B mRNA expression. Furthermore, we founded that tumors with higher CD8 + MeTIL score were marked with immunosuppressive characteristics, including low immune score and downregulated immune-related pathways. More importantly, the CD8 + MeTIL score showed a potential predictive value for the benefit from immunotherapy in two published cohorts. When combined CD8 + MeTIL with PD-L1 expression, the patient classification showed significantly different immunotherapy response rates and long-term survival outcomes. Conclusions: The CD8 + MeTIL signature might be as a novel method to evaluate CD8 + TILs and guide immunotherapy approaches. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Multitech-Based Study on Medicinal Material Basis and Action Mechanism of Herbal Formula Xian-Ling-Gu-Bao Capsule in Treatment of Osteoarthritis.
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Wu, Xiaowen, Sun, Shuai, Wu, Xiaoyi, and Sun, Zengxian
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IN vitro studies , *CARTILAGE cells , *LIPOPOLYSACCHARIDES , *HERBAL medicine , *MEDICINAL plants , *PHARMACEUTICAL encapsulation , *LIQUID chromatography , *PHYTOCHEMICALS , *CELLULAR signal transduction , *OSTEOARTHRITIS , *MASS spectrometry , *DESCRIPTIVE statistics , *DATA analysis software , *CHINESE medicine , *THERAPEUTICS - Abstract
Currently, osteoarthritis (OA) is thought to be the most prevalent chronic joint disease worldwide. The epidemiology of this disorder is complex, and the treatment is challenging. Xian-Ling-Gu-Bao (XLGB) capsule, a herbal compound preparation, is widely used for the treatment of bone disorders, including OA. Although its efficacy and safety have been demonstrated in clinical trials and practice, the underlying medicinal constituents and mechanism have not been clearly elucidated. Therefore, this study aimed to explore the medicinal constituents and mechanism of XLGB for OA treatment. The phytochemical constituents in XLGB capsule were detected by liquid chromatography-mass spectrometry (LC-MS), the medicinal constituents and therapeutic mechanism for OA treatment were deduced by network analysis, and the deduced mechanism was validated by in vitro experiment. As a result, a total of 55 constituents were detected in XLGB extract, in which 16 constituents were screened out for target collection. Based on the analysis of target profile, XLGB targets showed a high degree of similarity with OA targets. Network analysis revealed that XLGB had a holistic effect of multiple active constituents on multiple targets and pathways. The core targets of XLGB were presumed to be MAPKs, PI3K, AKT, BCL2, RELA, TNF, NOS2, and so on, and the mechanism was speculated to mainly inhibit chondrocyte apoptosis and inflammatory response through JNK and PI3K/AKT/NF-κB signaling cascades. Finally, in vitro study confirmed that XLGB extract protected ATDC5 cells against lipopolysaccharide- (LPS-) induced apoptosis and inflammatory response, and these effects were supposed to be involved in the inhibition of JNK and PI3K/AKT/NF-κB pathways. Our study could provide a scientific basis for further research and clinical use of XLGB capsule. [ABSTRACT FROM AUTHOR]
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- 2022
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5. Fluvial landscape change in Anqing through the last glacial cycle: Implications for eustatic controls on the Yangtze River's continental-scale incision-aggradation cycles.
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Wu, Xiaowen, Wang, Lei, Ta, La, Guo, Changhui, Qiao, Long, Wang, Huiying, Wang, Ping, Xu, Liubing, Xie, Jinming, Zhang, Jiafu, Wang, Xin, Wang, Chunxin, and Hu, Gang
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AGGRADATION & degradation , *LANDSCAPE changes , *OPTICALLY stimulated luminescence , *LAST Glacial Maximum , *OPTICALLY stimulated luminescence dating , *MARINE sediments - Abstract
The Yangtze River is known as the 'mother river of China' because it flows through the country's most densely populated and historically wealthiest regions. However, the evolution of the Yangtze River and its controls remain unclear. In this study we dated samples extracted from five bedrock-penetrated boreholes in Anqing, in the lower Yangtze River Valley. The resultant optically stimulated luminescence (OSL) and radiocarbon (14C) dates would suggest that fluvial sediments accumulated during the ∼33–44 ka and ∼11-0.2 ka periods, with extensive erosion during the >44 ka and 33-11 ka timeframes. We also reviewed data from 13 OSL and 14C dated boreholes located between the middle reaches of the Yangtze River and its estuary. The results would suggest that most of the fluvial sediments were deposited during Marine Isotope Stages (MIS) 3 and 1, with a clear erosion hiatus during the Last Glacial Maximum (LGM). Glacial-interglacial cycle-driven eustasy was the main driver of the Yangtze River's incision-aggradation process. The eustatic forcing during the glacial-interglacial cycle influenced the changes in the landscape of the Yangtze River Valley as far inland as ∼1200 km from the present-day shoreline. • Five boreholes were drilled in Anqing city, the lower Yangtze River Valley. • Most of the fluvial sediments were deposited during MIS 3 and 1. • Intensive incision occurred during the LGM and MIS 4. • Eustasy was the main driver of the Yangtze River's incision-aggradation process. • Eustatic forcing influenced fluvial landscape change as far inland as ∼1200 km. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Comprehensive Analysis of HMCN1 Somatic Mutation in Clear Cell Renal Cell Carcinoma.
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Gong, Ziqi, Wu, Xiaowen, Guo, Qian, Du, Haizhen, Zhang, Fenghao, and Kong, Yan
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RENAL cell carcinoma , *SOMATIC mutation , *GENETIC mutation , *ENERGY metabolism - Abstract
Background: Renal cell carcinoma (RCC) is a common malignancy of the genitourinary system and clear cell renal cell carcinoma (ccRCC) is the most representative subtype. The morbidity and mortality of ccRCC have gradually risen during recent years; however, the pathogenesis and potential biomarkers remain unclear. The purpose of our study was to find out prognostic genes correlated with somatic mutation and the underlying mechanisms of HMCN1 mutation in ccRCC. Methods: Somatic mutation data of two ccRCC cohorts were acquired from TCGA and cBioPortal. Genes frequently mutated in both datasets were extracted, from which tumor mutation burden and survival analysis revealed three prognostic genes. Further comprehensive analysis of HMCN1 mutation was carried out to identify differentially expressed genes and apply functional annotations. The correlation of HMCN1 mutation and tumor immunity was also evaluated. Results: HMCN1, SYNE1, and BAP1 mutations were associated with both tumor mutation burden and clinical prognosis in ccRCC. Gene enrichment analysis suggested the effects of HMCN1 mutation on biological processes and pathways linked to energy metabolism. HMCN1 mutation was also correlated with anti-tumor immunity. There were several limitations in the sample size and cohort availability of the present computational study. Conclusions: The present results inferred that HMCN1 mutation might have an important clinical significance for ccRCC patients by regulating metabolism and the immune microenvironment. [ABSTRACT FROM AUTHOR]
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- 2022
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7. Identification of the metabolites of methylophiopogonanone A by ultra‐high‐performance liquid chromatography combined with high‐resolution mass spectrometry.
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Wu, Xiaowen, Sun, Shuai, Wu, Xiaoyi, and Sun, Zengxian
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MASS spectrometry , *LIQUID chromatography , *LIVER microsomes , *METABOLITES , *DAUGHTER ions , *LIQUID chromatography-mass spectrometry , *PHARMACOKINETICS - Abstract
Rationale: Methylophiopogonanone A (MOA) is a naturally occurring homoisoflavonoid from the Chinese herb Ophiopogon japonicus, which has been demonstrated to attenuate myocardial apoptosis. However, the metabolism of MOA remains unknown. The goal of the present work was to investigate the in vitro metabolism of MOA using liver microsomes and hepatocytes. Methods: The metabolites were generated by incubating MOA with rat, monkey and human liver microsomes or hepatocytes. The resulting samples were analyzed by using a quadrupole‐orbitrap high‐resolution mass spectrometer. The metabolites were identified through the measurements of the exact mass, elemental composition and product ions. Results: A total of 15 metabolites were detected and identified. Among these metabolites, M7 (demethylenation) was the most abundant metabolite in liver microsomes, while M6 (hydroxylation) was the predominant metabolite in hepatocytes, and glucuronidation metabolites (M9 and M10) were also the main metabolites in hepatocytes. The metabolic pathways of MOA included hydroxylation, demethylenation, glucuronidation, methylation, sulfation and glutathione conjugation. Conclusions: This study for the first time provides valuable data on the metabolites of MOA, which will be of great importance for a better understanding of its disposition and to predict human pharmacokinetics. [ABSTRACT FROM AUTHOR]
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- 2022
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8. Safety, activity, and pharmacokinetics of camrelizumab in advanced Asian melanoma patients: a phase I study.
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Zhou, Li, Wu, Xiaowen, Chi, Zhihong, Si, Lu, Sheng, Xinan, Kong, Yan, Mao, Lili, Lian, Bin, Tang, Bixia, Yan, Xieqiao, Wang, Xuan, Bai, Xue, Li, Siming, Wei, Xiaoting, Li, Juan, Yang, Qing, Guo, Jun, and Cui, Chuanliang
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Background: Anti-programmed cell death receptor-1 (PD-1) monotherapy is the standard treatment for metastatic melanoma in current. Camrelizumab is a humanized IgG4 anti-PD-1 monoclonal antibody whose safety and efficacy have not been reported in advanced Asian melanoma patients.Methods: This phase I study investigated the safety, activity, and pharmacokinetics of camrelizumab in Chinese patients with advanced melanoma. The study included two phases, the dose-escalation phase ("3 + 3" design at 60 mg, 200 mg, and 400 mg) and the dose-expansion phase.Results: No dose-limiting toxicities were recorded over the dose-escalation phase, and the maximum tolerated dose was not reached. The most common treatment-related adverse events (TRAEs) in 36 patients were reactive cutaneous capillary endothelial proliferation, followed by rash, fever, hypothyroidism, hyperthyroidism, vitiligo, and fatigue. Five grade 3 or above TRAEs were reported (13.9%), including two cases of elevated γ-glutamyltransferase and blood triglycerides without clinical symptoms, and one liver injury recovered after symptomatic treatment. The confirmed overall response rate was 13.9% (95%CI: 4.7, 29.5%) and disease control rate was 38.9% (95%CI: 23.1, 56.5%). The median progression-free survival was 1.8 months (95%CI: 1.1, 2.4) and the median overall survival was 11.1 months (95%CI: 6.8, 15.4).Conclusions: Camrelizumab had acceptable tolerability and similar anti-tumor activity compared with other anti-PD-1 antibodies in advanced Asian melanoma patients.Trial Registration: ClinicalTrials.gov identification: NCT02738489. Registered on 14/04/2016, prospectively registered. [ABSTRACT FROM AUTHOR]- Published
- 2022
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9. Synthesis and Applications of SAPO‐34 Molecular Sieves.
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Yu, Wenhe, Wu, Xiaowen, Cheng, Bohao, Tao, Tianyi, Min, Xin, Mi, Ruiyu, Huang, Zhaohui, Fang, Minghao, and Liu, Yangai
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MOLECULAR sieves , *CATALYSIS , *POROSITY , *CHEMICAL industry , *ZEOLITE catalysts , *INDUSTRIAL goods , *CATALYSTS - Abstract
Silicoaluminophosphate zeolite (SAPO‐34) has been attracting increasing attention due to its excellent form selection and controllability in the chemical industry, as well as being one of the best industrial catalysts for methanol‐to‐olefin (MTO) reaction conversion. However, as a microporous molecular sieve, SAPO‐34 easily generates carbon deposition and rapidly becomes inactivated. Therefore, it is necessary to reduce the crystal size of the zeolite or to introduce secondary macropores into the zeolite crystal to form a hierarchical structure in order to improve the catalytic effect. In this review, the synthesis methods of conventional SAPO‐34 molecular sieves, hierarchical SAPO‐34 molecular sieves and nanosized SAPO‐34 molecular sieves are introduced, and the properties of the synthesized SAPO‐34 molecular sieves are described, including the phase, morphology, pore structure, acid source, and catalytic performance, in particular with respect to the synthesis of hierarchical SAPO‐34 molecular sieves. We hope that the review can provide guidance to the preparation of the SAPO‐34 catalysts, and stimulate the future development of high‐performance hierarchical SAPO‐34 catalysts to meet the growing demands of the material and chemical industries. [ABSTRACT FROM AUTHOR]
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- 2022
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10. Mesoscopic combinatorial design of anisotropic graphitic carbon with ordered porous frameworks for thermoelectric conversion.
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Duan, Shengzhi, Wu, Xiaowen, Ao, Weihua, Lei, Zhi, Leng, Guoqing, Fang, Minghao, Huang, Zhaohui, and Luo, Bingcheng
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THERMOELECTRIC conversion , *CARBON-based materials , *THERMOELECTRIC power , *THERMAL conductivity , *THERMOELECTRIC generators , *THERMOELECTRIC materials , *CARBON composites - Abstract
The incorporation of carbon materials can effectively enhance the performance of thermoelectric materials. By optimizing the thermoelectric properties of the carbon scaffold, it is possible to further improve the thermoelectric performance of the prepared carbon-based composites. To elevate the thermoelectric performance of the carbon scaffold, this work introduces a novel mesoscopic design strategy, utilizing natural flake graphite to create a three-dimensional ordered porous framework. Highly controllable anisotropic conductivity and thermal conductivity of the porous graphite skeleton were achieved, by combining sizable sodium chlorine templates (37.5–250 μm) with a natural flake graphite matrix (50–150 μm). A porous graphite with high electrical conductivity and low thermal conductivity along the vertical axis was obtained by carefully regulating the parameters. The sample demonstrated exceptional thermoelectric conversion performance, achieving a thermoelectric power factor of 12.2 μW m−1 K−2 and a figure of merit value of 28.3 × 10−4. Furthermore, the thermoelectric property of the samples could be greatly improved by adding a small amount of ferric chloride, with a thermoelectric power factor reaching 41.9 × 10−4 and a thermoelectric figure of merit reaching 81.4 μW m−1 K−2. This work provides an effective scheme for the mesoscopic regulation of porous graphite carbon structures and offers a new strategy for enhancing the performance of thermoelectric generators. [Display omitted] [ABSTRACT FROM AUTHOR]
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- 2024
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11. M6PS5X (M = Ag, Cu; X = Cl, Br) chalcohalides exhibiting strong nonlinear optical responses and high laser damage resistances.
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Gao, Lihua, Wu, Xiaowen, Yang, Daqing, Tian, Xinyu, Xu, Jingjing, Zhang, Bingbing, and Wu, Kui
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LASER damage , *LIGANDS (Chemistry) , *NONLINEAR optics , *CRYSTALS - Abstract
A series of M6PS5X (M = Ag, Cu; X = Cl, Br) nonlinear optical (NLO) chalcohalides with special MS3X ligands have been synthesized in this work. Their critical optical performances were systematically measured and the research results show that all of them exhibit strong NLO responses (2.0–2.7 × commercial AgGaS2) and high laser-damage thresholds (1.7–2.3 × AgGaS2), indicating their potential application as good NLO candidates. Furthermore, first-principles calculations were used to study their inherent structure–property relationships and chalcohalides can be expected to be optimal systems for the exploration of new promising IR NLO crystals. [ABSTRACT FROM AUTHOR]
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- 2021
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12. Recent Advances in Three-Dimensional Stem Cell Culture Systems and Applications.
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Wu, Xiaowen, Su, Junxiang, Wei, Jizhen, Jiang, Nan, and Ge, Xuejun
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STEM cell culture , *CELL culture , *EXTRACELLULAR matrix , *CELL growth , *STEM cells - Abstract
Cell culture is one of the most core and fundamental techniques employed in the fields of biology and medicine. At present, although the two-dimensional cell culture method is commonly used in vitro, it is quite different from the cell growth microenvironment in vivo. In recent years, the limitations of two-dimensional culture and the advantages of three-dimensional culture have increasingly attracted more and more attentions. Compared to two-dimensional culture, three-dimensional culture system is better to realistically simulate the local microenvironment of cells, promote the exchange of information among cells and the extracellular matrix (ECM), and retain the original biological characteristics of stem cells. In this review, we first present three-dimensional cell culture methods from two aspects: a scaffold-free culture system and a scaffold-based culture system. The culture method and cell characterizations will be summarized. Then the application of three-dimensional cell culture system is further explored, such as in the fields of drug screening, organoids and assembloids. Finally, the directions for future research of three-dimensional cell culture are stated briefly. [ABSTRACT FROM AUTHOR]
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- 2021
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13. Investigation on drug entrapment location in liposomes and transfersomes based on molecular dynamics simulation.
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Wu, Xiaowen, Dai, Xingxing, Liao, Yuyao, Sheng, Mengke, and Shi, Xinyuan
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MOLECULAR dynamics , *RADIAL distribution function , *NANOTECHNOLOGY , *POTENTIAL functions , *LIPOSOMES - Abstract
In this study, liposome and transfersome were successfully constructed using molecular dynamics simulation. Three drugs with different polarity, including 5-fluorouracil, ligustrazine, and osthole, were selected as model drugs to study the distribution of drugs in lipid vesicles by calculating the radial distribution function and the potential of mean force. The solubility parameters between drugs and different regions in lipid vesicles were calculated to characterize the compatibility of drugs in different regions in lipid vesicles, which provided the basis for the conclusion of this paper. It showed that the radial distribution function and the potential of mean force were consistent in the characterization of drug distribution in vesicles, and the drug distribution in vesicles was closely related to the compatibility between drugs and vesicles. Therefore, the radial distribution function and the potential of mean force can be used to characterize the distribution of drugs in vesicles, and molecular simulation technology has a great potential in studying the characteristics of vesicles. [ABSTRACT FROM AUTHOR]
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- 2021
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14. Pulse EPR spectroscopy and molecular modeling reveal the origins of the local heterogeneity of dietary fibers.
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Syryamina, Victoria N., Wu, Xiaowen, Boulos, Samy, Nyström, Laura, and Yulikov, Maxim
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ELECTRON paramagnetic resonance spectroscopy , *MOLECULAR spectroscopy , *DIETARY fiber , *SPIN labels , *ELECTRON paramagnetic resonance , *DISTRIBUTION (Probability theory) , *POLYMER solutions - Abstract
Optimizing human diet by including dietary fibers would be more efficient when the fibers' chain interactions with other molecules are understood in depth. Thereby, it is important to develop methods for characterizing the fiber chain to be able to monitor its structural alterations upon intermolecular interactions. Here, we demonstrate the utility of the electron paramagnetic resonance (EPR) spectroscopy, complemented by simulations in probing the atomistic details of the chain conformations for spin-labeled fibers. Barley β-glucan, a native polysaccharide with linear chain, was utilized as a test fiber system to demonstrate the technique's capabilities. Pulse dipolar EPR data show good agreement with results of the fiber chain modeling, revealing sinuous chain conformations and providing polymer shape descriptors: the gyration tensor, spin-spin distance distribution function, and information about proton density near the spin probe. Results from EPR measurements point to the fiber aggregation in aqueous solution, which agrees with the results of the dynamic light scattering. We propose that the combination of pulse EPR measurements with modeling can be a perfect experimental tool for in-depth structural investigation of dietary fibers and their interaction under such conditions, and that the presented methodology can be extended to other weakly ordered or disordered macromolecules. [Display omitted] • EPR data augmented by modeling describe conformational distributions of dietary fiber. • Heterogeneities in fibers result in strong T m -filtering in pulse EPR data. • The proposed methodology can have broad applications to polymer solutions. [ABSTRACT FROM AUTHOR]
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- 2023
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15. Simple routes from natural graphite to graphite foams: Preparation, structure and properties.
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Duan, Shengzhi, Wu, Xiaowen, Zeng, Keqing, Tao, Tianyi, Huang, Zhaohui, Fang, Minghao, Liu, Yangai, and Min, Xin
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THERMAL diffusivity , *FOAM , *GRAPHITE , *RAW materials , *SCANNING electron microscopes , *X-ray fluorescence , *RECYCLABLE material - Abstract
Graphite foams were prepared using foaming method and template method with nature flake graphite powder as main raw materials, sucrose as a foaming agent or binder, as well sodium chloride as a template. The compositions, microstructure, thermal properties and mechanical performance of the fabricated graphite foams were investigated by X-ray fluorescence spectrometer, scanning electron microscope, laser thermal conductivity meter, and electronic universal testing machine, respectively. The results show that water in binder played an important role in forming process of graphite foams. Graphite foams with controllable pore structure can be obtained by template method. The porosity of graphite foams increased with increasing the concentration of templating agent. With a fixed concentration of the templating agent the thermal diffusivity of the foams deceased with increasing the concentration of binder. Moreover, the obtained graphite foams has a minimum density of 288 kg/m3, a maximum porosity of 78% and a maximum thermal diffusivity of 7.14 × 10−6 m2/s. Two binding models of graphite foams prepared using template method has been proposed in the first time. This work provided an optimized processing for graphite foams with simple preparation, low-cost recyclable raw materials, and a promising thermal management material for many applications. Image 1 • New type of graphite foams were developed using natural flake graphite as main raw material. • Two binding models of graphite foams prepared using template method has been proposed. • Water can promote the pore-forming during the forming process of graphite foams. • The routes have superiority of simple, low-cost with recyclable raw materials. [ABSTRACT FROM AUTHOR]
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- 2020
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16. Loss of Gsdf leads to a dysregulation of Igf2bp3-mediated oocyte development in medaka.
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Wu, Xiaowen, Zhang, Yingqing, Xu, Shumei, Chang, Yuyang, Ye, Yang, Guo, Anning, Kang, Yi, Guo, Haiyan, Xu, Hongyan, Chen, Liangbiao, Zhao, Xiaomiao, and Guan, Guijun
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ORYZIAS latipes , *SOMATOMEDIN A , *RNA-binding proteins , *GERM cells - Abstract
• Igf2bp3 was strongly upregulated in the gsdf -deficient ovary in medaka. • Igf2bp3 plays an essential role in oocyte development across phyla. • gsdf depletion led to a dysregulation of Igf2bp3-mediated oocyte development in medaka. Gonadal soma-derived factor (Gsdf) is a unique TGF-β factor essential for both ovarian and testicular development in Hd-rR medaka (Oryzias latipes). However, the downstream genes regulated by Gsdf signaling remain unknown. Using a high-throughput proteomic approach, we identified a significant increase in the expression of the RNA-binding protein Igf2bp3 in gsdf -deficient ovaries. We verified this difference in transcription and protein expression against normal gonads using real-time PCR quantification and Western blotting. The genomic structure of igf2bp3 and the syntenic flanking segments are highly conserved across fish and mammals. igf2bp3 expression was correlated with oocyte development, which is consistent with the expression of the igf2bp3 ortholog Vg1-RBP/Vera in Xenopus. In contrast to the normal ovary, cysts of H3K27me3- and Igf2bp3-positive germ cells were dramatically increased in the one-month-old gsdf -deficient ovary, indicating that the gsdf depletion led to a dysregulation of Igf2bp3-mediated oocyte development. Our results provide novel insights into the Gsdf-Igf2bp3 signaling mechanisms that underlie the fundamental process of gametogenesis; these mechanisms may be well conserved across phyla. [ABSTRACT FROM AUTHOR]
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- 2019
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17. Anti-tumor effect of aloe-emodin on cervical cancer cells was associated with human papillomavirus E6/E7 and glucose metabolism.
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Gao, Rui, Wu, Xiaowen, Huang, Zhi, Wang, Bi, Li, Fenghu, Xu, Hui, and Ran, Li
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GLUCOSE metabolism , *CANCER cells , *CERVICAL cancer , *HELA cells , *POLYMERASE chain reaction - Abstract
Background: Aloe-emodin, an anthraquinone present in aloe latex, has been shown to have anti-proliferative properties in cervical cancer disease, all cases of which are almost caused by human papillomavirus (HPV), with the products of E6/E7. It is suggested that aloe-emodin may play an important role in HPV-induced cervical cancer cells. Methods: Hela and SiHa cells were treated with various concentrations of aloe-emodin. MTT assay and flow cytometry were used to identify the cell growth and apoptosis. The expressions of HPV E6, E7 and GLUT1 (glucose transporter-1) were detected by real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot (WB). The glucose uptake, lactate production and ATP production in HeLa and SiHa cells were also investigated. Result: The results indicate that aloe-emodin promoted the apoptosis of HeLa and SiHa cells and decreased the expressions of HPV-related protein E6 and E7. Furthermore, aloe-emodin inhibited glucose metabolism by reducing GLUT1 expression. Overexpression of GLUT1 significantly weakened the apoptosis induced by aloe-emodin in HeLa cells. Conclusion: In this study, we found that aloe-emodin induce apoptosis of cervical cancer cells, which was associated with HPV E6 and E7 and glucose metabolism. [ABSTRACT FROM AUTHOR]
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- 2019
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18. Genetic diversity and metapopulation structures of two intertidal species along the coast of Zhejiang, China: implications for conservation.
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Peng, Xin, Wu, Xiaowen, Zhang, Yongpu, Zhang, Huawei, Tang, Jiu, and Kang, Bin
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MICROSATELLITE repeats , *MARINE parks & reserves , *CYTOCHROME oxidase , *RIBOSOMAL RNA , *MITOCHONDRIAL DNA , *GENE flow - Abstract
To priority areas for conservation in the coast of Zhejiang, this study attempts to map the spatial patterns of the intra-specific genetic diversity of two intertidal species, Septifer virgatus and Tetraclita japonica, using the sequences of mitochondrial DNA cytochrome oxidase subunit I (COI) and large subunit ribosomal RNA (16S rRNA) genes. In total, 129 and 112 specimens were collected from 12 and 11 populations for S. virgatus and T. japonica, respectively. These two species revealed congruent population historical signals, including (1) high levels of haplotype diversity and low values of nucleotide diversity, (2) post-LGM expansion, (3) the lack of population genetic structure, sharing haplotypes over all sampling populations, (4) gene flow connections, and (5) migration directions. Largely, all results supported that all sampling populations could be divided into two main metapopulations, exhibiting a northern and southern distribution. The north metapopulation could be considered as a marine protected area. The genetic patterns of the two species should be considered in the management and conservation in the islands along the Zhejiang, China. [ABSTRACT FROM AUTHOR]
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- 2019
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19. Investigation on two new antimony-based quaternary chalcogenides: Na6CdSb4S10 and Na3CdSbSe4.
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Huang, Yi, Wu, Xiaowen, and Beysen, Sadeh
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CHALCOGENIDES , *ANTIMONY compounds , *MOLECULAR structure - Abstract
Two new quaternary chalcogenides, Na6CdSb4S10 and Na3CdSbSe4, were successfully synthesized by the high-temperature solid-state reaction in vacuum-sealed silica tubes. Note that Na6CdSb4S10 crystallizes in the C2/c space group, whereas Na3CdSbSe4 crystallizes in the P21/c space group. As seen from their structures, Na6CdSb4S10 exhibits a three-dimensional (3D) framework structure composed by the interconnection of isolated [(Cd/Sb)2Sb2S10] clusters and two different layers formed by the NaSn (n = 4, 6) units; besides, the structure of Na3CdSbSe4 is composed of isolated ∞(Cd3Sb2Se12)n chains and 2D layers formed by the NaSen (n = 5, 6) units. Their optical performances (bandgap and Raman spectra) were also investigated. Moreover, theoretical calculation was used to analyze the structure–performance relationship of Na3CdSbSe4. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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20. Structural insights into T2-cluster-containing chalcogenides with vertex-, edge- and face-sharing connection modes of NaQ6 ligands: Na3ZnMIIIQ4 (MIII = In, Ga; Q = S, Se).
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Chen, Ruijiao, Wu, Xiaowen, and Su, Zhi
- Subjects
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CHALCOGENIDES synthesis , *METAL clusters , *LIGANDS (Chemistry) , *HIGH temperatures , *CHEMICAL reactions , *MOLECULAR structure - Abstract
A series of quaternary chalcogenides, Na3ZnMIIIQ4 (MIII = In, Ga; Q = S, Se), were successfully synthesized for the first time through a high temperature solid-state reaction method. All of them exhibit similar structures and crystallize in the I41/acd space group of the tetragonal system. In their structures, typical super-tetrahedron (T2-type) clusters composed of four vertex-sharing (Zn/MIII)S4 tetrahedra are discovered and these T2-clusters further link together to form interesting wavelike chains. Adjacent T2 clusters present a torsion angle of 24.6° with each other when viewed along the c-axis, which has rarely been found among all the reported T2-containing chalcogenides. Moreover, we have systematically investigated the connection modes of NaSn (n = 4–6) in all the known Na-contained quaternary sulfides, and the result shows that the connection modes (corner-, edge-, and face-sharing) of NaS6 ligands in the title sulfides are also rarely (only 3%) found. Besides, the optical properties including diffuse-reflection and Raman spectra are systematically characterized. Theoretical calculations based on the first principles theory were also used to analyze their structure–performance relationships. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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21. Interaction of barley β-glucan with food dye molecules – An insight from pulse dipolar EPR spectroscopy.
- Author
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Wu, Xiaowen, Boulos, Samy, Syryamina, Victoria, Nyström, Laura, and Yulikov, Maxim
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COLORING matter in food , *BETA-glucans , *SPIN labels , *ELECTRON paramagnetic resonance , *SMALL molecules , *ELECTRON paramagnetic resonance spectroscopy , *BARLEY - Abstract
The interactions between dietary fibers (DFs) and small molecules are of great interest to food chemistry and nutrition science. However, the corresponding interaction mechanisms and structural rearrangements of DFs at the molecular level are still opaque due to the usually weak binding and the lack of appropriate techniques to determine details of conformational distributions in such weakly organized systems. By combining our previously established methodology on stochastic spin-labelling of DFs with the appropriately revised set of pulse electron paramagnetic resonance techniques, we present here a toolkit to determine the interactions between DFs and small molecules, using barley β-glucan as an example for neutral DF and a selection of food dye molecules as examples for small molecules. The proposed here methodology allowed us to observe subtle conformational changes of β-glucan by detecting multiple details of the local environment of the spin labels. Substantial variations of binding propensities were detected for different food dyes. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2023
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22. miR-494-5p mediates the antioxidant activity of EPA by targeting the mitochondrial elongation factor 1 gene MIEF1 in HepG2 cells.
- Author
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Lin, Yanqi, Wu, Xiaowen, Lin, Lingli, Mei, Yuanyuan, Zhou, Jing, Chen, Chaoxiang, Li, Jian, Wu, Daren, Liu, Jingwen, and Li, Guiling
- Subjects
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OXIDANT status , *MITOCHONDRIA , *REACTIVE oxygen species , *OXIDATIVE stress , *EICOSAPENTAENOIC acid , *HOMEOSTASIS - Abstract
Eicosapentaenoic acid (EPA) shows antioxidant activity, which may be attributed to its regulatory effect on microRNA expression. Our preliminary study indicated that EPA upregulated miR-494-5p, which was possibly involved in the regulation of cellular stress responses. The current study aimed to address whether miR-494-5p was targeted by EPA to regulate cellular oxidative stress and its possible functional mechanism. The results showed that miR-494-5p mediated the antioxidant effect of EPA and miR-494-5p reduction deteriorated EPA-induced increase in the cellular antioxidant capacity of HepG2 cells. Moreover, the mitochondrial elongation factor 1 (MIEF1) gene was a target gene of miR-494-5p. Both miR-494-5p overexpression and MIEF1 knockdown significantly enhanced cellular antioxidant capacity, as indicated by a reduction in the reactive oxygen species level and an increase in the total cellular antioxidant capacity, along with enhancing antioxidant enzymes. Thus, miR-494-5p and MIEF1 had opposite effects on cellular antioxidant capacity. Furthermore, their regulatory effects on oxidative stress may have been attributed to modulation of mitochondrial function, biogenesis and homeostasis. Taken together, the findings indicated that miR-494-5p mediated EPA activity and promoted cellular antioxidant capacity by inhibiting the expression of MIEF1 , which further modulated mitochondrial structure and activity. This study may provide novel insights into the post-translational regulation of antioxidation reactions, which involves the coordinated control of mitochondria. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2023
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23. PI3K/AKT/mTOR pathway inhibitors inhibit the growth of melanoma cells with mTOR H2189Y mutations in vitro.
- Author
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Wu, Xiaowen, Yu, Jiayi, Yan, Junya, Dai, Jie, Si, Lu, Chi, Zhihong, Sheng, Xinan, Cui, Chuanliang, Ma, Meng, Tang, Huan, Xu, Tianxiao, Yu, Huan, Kong, Yan, and Guo, Jun
- Abstract
mTOR is an important therapeutic target in many types of cancers. In melanoma, the mTOR nonsynonymous mutation rate is up to 10.4%. However, mTOR inhibitors have shown limited effects in clinical trials of melanoma. Because mTOR mutations are distributed, not selecting patients with specific mTOR mutations may be the main reason for therapeutic failures. Our previous research found that mutations in the mTOR P2213S and S2215Y kinase domains resulted in gain-of-function and were sensitive to specific inhibitors. The purpose of this study was to test the effect of heterozygous/homozygous H2189Y mutations on downstream pathways and sensitivity to inhibitors. mTOR kinase activity was analyzed by western blot and a K-LISA™ mTOR activity kit. The sensitivity of melanoma cells to inhibitors was tested by a proliferation assay. The expression of downstream pathway proteins was also analyzed by western blot. The results showed that heterozygous/homozygous H2189Y mutations were gain-of-function. The heterozygous H2189Y mutation was sensitive to the AKT inhibitor, AZD5363, and the phosphoinositide 3-kinase inhibitor, LY294002. The homozygous H2189Y mutation was sensitive to the mTOR inhibitor, everolimus, and the AKT inhibitors AZD5363 and MK-2206 2HCL,and the phosphoinositide 3-kinase inhibitor, LY294002. These results indicated that homozygous mutations in the kinase domain have a greater effect on protein function than heterozygous mutations. The mTOR kinase domain may play an important role in mTOR kinase activity and may be the target of selective inhibitors. Our study can facilitate the selection of appropriate inhibitors for patients in clinical trials. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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24. Electric Resistance Tests on Compacted Clay Material under Dynamic Load Coupled with Dry-Wet Cycling.
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Lu, Zheng, Wu, Xiaowen, Hu, Zhi, Xian, Shaohua, and Fang, Ran
- Subjects
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DYNAMIC testing of materials , *SOIL compaction , *CLAY minerals , *ELECTRIC resistance , *STRAINS & stresses (Mechanics) - Abstract
The study of compacted clay material under dynamic load coupled with dry-wet cycling is one of the most important areas in the field of transportation. In this paper, experiments in terms of compacted clay under dynamic load coupled with dry-wet cycling are performed, and synchronous resistivity tests are also conducted. According to the test results, the influences of cumulative plastic strain, dry-wet cycles, and amplitudes on the soil resistivity are analyzed. Then a new damage factor based on resistivity is proposed to evaluate the long-term performance of compacted clay material. The result of research shows that the evolution of the soil resistivity can be divided into two stages, which has a contrary tendency with that of cumulative plastic strain. The dry-wet cycles and amplitudes have a significant effect on the damage of the compacted soil, which indicates that the dry-wet cycling of compacted soil materials should not be ignored in road engineering, especially in rainy and humid areas. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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25. A segmented attitude planning and controlling method for agile satellite based on Pseudospectral method.
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Zhao, Lin, Wu, Xiaowen, Liu, Yuan, and Hao, Yong
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PSEUDOSPECTRUM , *AGILE software development , *ARTIFICIAL satellites , *ANGULAR velocity , *OPTIMAL control theory - Abstract
To fulfil the high precision requirements of the manoeuvre imaging mode of an agile satellite and solve the shortcomings of existing methods, a segmented attitude planning method based on the Pseudospectral method is proposed. First, a state equation was built by integrating the attitude constraint, time window and other restrictions. Furthermore, to guarantee the accuracy and stability of objects, a segmented strategy of an attitude trajectory approaching the imaging target using a constant angular velocity was proposed. The segmented time, three-axis position and velocity were also determined. Second, taking the global performance into account, the first section of the attitude trajectory was planned by the Legendre Pseudospectral method in order to acquire the optimal state variables and control variables. The second section of the attitude trajectory was then obtained by the constant angular velocity planning method. Next, in order to track the planning trajectory efficiently, a PD controller was designed that was suitable for a segmented planning method. High precision control parameters were obtained by the optimized method. Finally, numerical simulation results show that the proposed segmented attitude planning method successfully meets the high precision requirements of the manoeuvre imaging mode, and the feasibility and effectiveness of this method is verified. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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26. Novel humic acid-based carbon materials: adsorption thermodynamics and kinetics for cadmium(II) ions.
- Author
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Jin, Xiaozhao, Wu, Xiaowen, Zhang, Haiyan, Jiang, Xiaoting, Huang, Zhaohui, Liu, Yan’gai, Fang, Minghao, and Min, Xin
- Subjects
- *
HUMIC acid , *CADMIUM , *CARBONIZATION , *CHEMICAL reactions , *LANGMUIR isotherms - Abstract
Novel humic acid-based carbon materials were prepared by using carbonization and activation in the present paper. The effects of processing and temperatures on the microstructure and the adsorption ability of cadmium ion were investigated. The functional groups, thermal stability, pore structure, and morphology of products were characterized. The results showed that the oxygen functional groups decreased and the pore structure increased with increasing carbonization temperature. The adsorption kinetics of cadmium(II) on humic acid-based carbon materials could be expressed by the pseudo-second-order kinetic model, and the adsorption isotherm of carbonized samples and activated samples was fitted by Langmuir model and Freundlich model respectively. It indicated that the adsorption of cadmium(II) on carbonized humic acid was controlled by the chemical reaction and occurred on the monolayers surface, while the adsorption of cadmium(II) on carbonized humic acid was controlled by the chemical reaction and occurred on the heterogeneous surface. The adsorption quantity increased with pH from 2 to 6 and remained constant up to pH 6. The equilibrium adsorption quantity increased with carbonization temperature from 12.3 mg/g at 400 °C to 17.4 mg/g at 800 °C. After activated at 600 °C, the humic acid-based carbon achieved the maximum adsorption quality (26.3 mg/g). [ABSTRACT FROM AUTHOR]
- Published
- 2018
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27. Analysis of NRAS gain in 657 patients with melanoma and evaluation of its sensitivity to a MEK inhibitor.
- Author
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Yan, Junya, Wu, Xiaowen, Yu, Jiayi, Yu, Huan, Xu, Tianxiao, Brown, Kevin M., Bai, Xue, Dai, Jie, Ma, Meng, Tang, Huan, Si, Lu, Chi, Zhihong, Sheng, Xinan, Cui, Chuanliang, Kong, Yan, and Guo, Jun
- Subjects
- *
MELANOMA prognosis , *DNA analysis , *CELL lines , *MELANOMA , *GENETIC mutation , *NEUROBLASTOMA , *PROBABILITY theory , *SURVIVAL , *TRANSFERASES , *XENOGRAFTS , *DESCRIPTIVE statistics - Abstract
Background Neuroblastoma rat-sarcoma ( NRAS ) mutations have been described in Chinese patients with melanoma. However, the status and the clinical significance of NRAS gain have not been investigated on a large scale. Methods A total of 657 melanoma samples were included in the study. NRAS copy number was examined using the QuantiGene Plex DNA assay. The sensitivities of cell lines and patient-derived xenograft (PDX) models containing NRAS gain to a MAP/ERK kinase (MEK) inhibitor (binimetinib) were also evaluated. Results The overall incidence of NRAS gain was 14.0% (92 of 657). Incidence of NRAS gain in acral, mucosal, chronic sun-induced damage (CSD) and non-CSD melanomas was 12.2%, 15.8%, 9.5% and 19.4%, respectively. NRAS gain was mutually exclusive to NRAS mutations ( P = 0.036). The median survival time for melanoma patients with NRAS gain was significantly shorter than that for patients with normal NRAS copy number ( P = 0.006). For patients containing NRAS gain, the median survival time for higher copy number (>4 copies) was significantly shorter than those with lower copy number (2–4 copies; P = 0.002). The MEK inhibitor (binimetinib) inhibited the proliferation of melanoma cells and the tumour growth of PDX models with NRAS gain. Conclusions NRAS gain is frequent in patients with melanoma and may predict a poor prognosis of melanoma. The melanoma cells and PDX models containing NRAS gain are sensitive to MEK inhibitor (binimetinib), indicating that NRAS gain might be a new therapeutic target for melanoma. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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28. Anti-GD2/4-1BB chimeric antigen receptor T cell therapy for the treatment of Chinese melanoma patients.
- Author
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Yu, Jiayi, Wu, Xiaowen, Yan, Junya, Yu, Huan, Xu, Longwen, Chi, Zhihong, Sheng, Xinan, Si, Lu, Cui, Chuanliang, Dai, Jie, Ma, Meng, Xu, Tianxiao, Kong, Yan, and Guo, Jun
- Subjects
- *
CHIMERIC antigen receptors , *T cells , *CELL-mediated cytotoxicity , *MELANOMA treatment , *GANGLIOSIDES - Abstract
Background: Chimeric antigen receptor (CAR)-engineered T cells have demonstrated promising clinical efficacy in patients with B cell lymphoma. However, the application of CAR-T cell therapy in the treatment of other solid tumors has been limited. We incorporated 4-1BB into the anti-GD2 CAR-T cells to test their cytotoxicity in melanoma in vitro and in vivo. Moreover, we reported the expression of ganglioside GD2 in non-Caucasian melanoma populations for the first time, thus providing a basis for future clinical research. Methods: This study included tumor samples from 288 melanoma patients at the Peking University Cancer Hospital & Institute. Clinical data were collected. Immunohistochemical assays using antibodies against ganglioside GD2 were performed on formalin-fixed, paraffin-embedded specimens. The ability of ganglioside GD2 CAR-T cells to kill ganglioside GD2+ melanoma cells was evaluated in vitro and in a patient-derived xenograft (PDX) model. Results: Among the 288 samples, 49.3% of cases (142/288) demonstrated positive staining with ganglioside GD2. The median survival time in patients exhibiting ganglioside GD2 expression was significantly shorter than that in patients without ganglioside GD2 expression (31 vs. 47.1 months, P < 0.001). In the present study, CAR was constructed using a GD2-specific scFv (14.G2a), T cell receptor CD3ζ chain, and the CD137 (4-1BB) costimulatory motif. In addition, the GD2. BBζ CAR-T cells demonstrated specific lysis of ganglioside GD2-expressing melanoma cells in vitro. In two PDX models, mice that received intravenous or local intratumor injections of GD2.BBζ CAR-T cells experienced rapid tumor regression. Conclusions: These data demonstrate that the rate of GD2 expression in Chinese patients is 49.3%. GD2.BBζ CAR-T cells can both efficiently lyse melanoma in a GD2-specific manner and release Th1 cytokines in an antigen-dependent manner in vitro and in vivo. Anti-GD2/4-1BB CAR-T cells represent a clinically appealing treatment strategy for Chinese melanoma patients exhibiting GD2 expression and provide a basis for future studies of the clinical application of immunotherapy for melanoma. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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29. Evolution of self-generating porous microstructures in polyacrylonitrile-cellulose acetate blend fibres.
- Author
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Mahalingam, Suntharavathanan, Wu, Xiaowen, and Edirisinghe, Mohan
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POLYACRYLONITRILES , *MICROSTRUCTURE , *CELLULOSE acetate , *POLYMER blends , *SOLVENTS - Abstract
Polyacrylonitrile (PAN), cellulose acetate (CA) and polyacrylonitrile - cellulose acetate (PAN-CA) fibres were formed in single and binary solvents which were subjected to gyration under pressure. Fibres in the diameter range 200–2000 nm were generated using a rotating speed of 36,000 rpm and a working pressure of 3 × 10 5 Pa. Long fibre morphologies with isotropic distribution of fibre orientation were obtained from PAN polymer solutions with a concentration of 5–15 wt%. Short fibre morphologies with anisotropic distribution of fibre orientation were produced for CA polymer solutions with a concentration of 25 wt% and below this concentration polygonal beads were generated. PAN-CA fibre bundles were generated and these showed remarkable self-generating porous characteristics when the working pressure was changed from 1 to 3 × 10 5 Pa. For comparison, porous PAN-CA fibres were also generated by solvent etching and porogen leaching techniques and in these the etching time and porogen concentration influenced the pore size of the generated fibres. Fourier transform infrared and Raman spectroscopies were performed to elucidate the bonding characteristics in the fibres. Release characteristics of the porous fibrous structures were studied using vanillin as the active ingredient. A mathematical model which allows the evaluation of the fibre diameter as a function of rotating speed and working pressure is presented and this helps to understand the solvent mass transfer taking place during fibre forming. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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30. Magnetically recoverable Ni@C composites: The synthesis by carbonization and adsorption for Fe3+.
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Wu, Xiaowen, Zhang, Zhijie, Xia, Chao, Chen, Biqiong, Jin, Xiaozhao, Huang, Zhaohui, Liu, Yan-gai, Fang, Minghao, and Min, Xin
- Subjects
- *
CARBONIZATION , *ADSORPTION (Chemistry) , *NICKEL , *MAGNETIZATION , *CHEMICAL synthesis - Abstract
Carbon-encapsulated nickel particles ( Ni@C composites) for removing Fe 3+ in wastewater have been prepared by the carbonization of phenolic resin mixing with nickel particles. XRD results reveal that the Ni@C composites are consisted of C, Ni, and Ni 3 S 2 . The TG-DTG curves of Ni@C composites are almost same as that of phenolic resin. The morphology investigation shows that Ni is distributed randomly on carbon. Based on analysis of N 2 adsorption-desorption isotherm, the surface area and pore volume of Ni@C composites are 187.47 m 2 g −1 and 0.06900 cm 3 g −1 nm −1 , respectively. The saturation magnetization values for Ni@C composites are 68.99 emu·g −1 determined by the Vibrating Sample Magnetometer. Ni@C composites exhibit a high adsorption capacity for Fe 3+ . The adsorption behavior follows the pseudo-second-order kinetic and Langmuir model between the adsorbents and Fe 3+ . Furthermore, the adsorption capacity of Ni@C composites derives from the attractive force between the adsorbed anion and the surface positive charge of Ni@C composites, as well as the bond between the adsorbed cation and the COO − groups. From the above results Ni@C composites can be widely applied in wastewater treatment as a new efficiency and excellent recoverable adsorbent. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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31. Preparation and characterization of (betamethasone sodium phosphate intercalated layered double hydroxide)@liposome nanocomposites.
- Author
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Zhang, Yaping, Wu, Xiaowen, Li, Haiping, Du, Na, Song, Shue, and Hou, Wanguo
- Subjects
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SODIUM phosphates , *HYDROXIDES , *LIPOSOMES , *LECITHIN , *CHOLESTEROL , *NANOCOMPOSITE materials - Abstract
Herein, we report a nanocomposite of betamethasone sodium phosphate (BMP), a glucocorticoid drug, intercalated layered double hydroxide (LDH) nanohybrids encapsulated in liposomes, denoted as BLN@LSs. The BMP-LDH nanohybrids (BLNs) were firstsynthesized via a coassembly route between BMP anions and LDH single-layer nanosheets (SLNSs), and then coated with liposomes consisting of lecithin and cholesterol. The re-dispersity, stability, and drug release behavior of the so-obtained nanocomposites were investigated. Compared with BLNs, the BLN@LSs exhibit excellent water re-dispersity and stability as well as enhanced drug sustained-release performance. The drug release processes can be described using the pseudo-second-order kinetic model, and intraparticle diffusion is the release rate-limiting step. Our work demonstrates that liposome-coating for drug-LDH nanohybrids is an effective strategy to enhance their water dispersity and sustained-release performances, and that (drug-LDH)@LS nanocomposites are a potential drug delivery system. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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32. Engineering of (10-hydroxycamptothecin intercalated layered double hydroxide)@liposome nanocomposites with excellent water dispersity.
- Author
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Zhang, Yongfang, Wu, Xiaowen, Mi, Yuwei, Li, Haiping, and Hou, Wanguo
- Subjects
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LAYERED double hydroxides , *LIPOSOMES , *NANOCOMPOSITE materials , *ANTINEOPLASTIC agents , *LACTATE dehydrogenase - Abstract
A hierarchical nanocomposite of 10-hydroxycamptothecin (HCPT), a nonionic and lipophilic anticancer drug, intercalated layered double hydroxide (LDH) encapsulated in liposomes was constructed. HCPT molecules were first incorporated into sodium cholate (Ch) micelles, and the resultant negatively charged HCPT-loaded Ch micelles were then co-assembled with positively charged LDH single-layer nanosheets, forming a HCPT/Ch intercalated LDH (HCPT-Ch-LDH) host-gest nanohybrid. The nanohybrid particles were further coated with liposomes (LSs), gaining a core-shell nanocomposite, denoted as (HCPT-Ch-LDH)@LS. The so-obtained samples were characterized using TEM, SAXS, FT-IR, DLS, and elemental analyses. Special emphasis was placed on the effect of liposome-coating for the HCPT-Ch-LDH on its water dispersity and drug-release. The results showed that the nanocomposite has excellent water dispersity and enhanced drug sustained-release performance in comparison with the HCPT-Ch-LDH, demonstrating that the liposome-coating for drug-LDH nanohybrids is an effective strategy to enhance their water dispersity and sustained-release performances. This work provides an effective strategy for engineering of LDH-based delivery systems for nonionic and lipophilic drugs. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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33. Printable graphite-based thermoelectric foam for flexible thermoelectric devices.
- Author
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Duan, Shengzhi, Wang, Yifan, Wu, Xiaowen, Wu, Meihua, Wang, Lianyi, Fang, Minghao, Huang, Zhaohui, and Luo, Ruiying
- Subjects
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THERMOELECTRIC apparatus & appliances , *FOAM , *THERMOELECTRIC materials , *SEEBECK coefficient , *RAW materials , *PRINTMAKING - Abstract
Flexible thermoelectric materials are primarily composed of organic thermoelectric materials, which suffer from issues such as instability and poor conductivity. To overcome these limitations, this study aims to develop a cost-effective thermoelectric material by utilizing graphite and hydroxypropyl methylcellulose as raw materials. Through a mechanical foaming process, a graphite-based foam with a porous structure is fabricated. The obtained foam exhibits a Seebeck coefficient of approximately 32 μV K−1 and a power factor of around 0.013 μW m−1 K2. Following an analysis of the microstructural morphology, the foam samples are subjected to compression treatment to convert the 3D foam into a porous film and thereby enhance the power generation efficiency of the thermoelectric material. Notably, the Seebeck coefficient of the compressed sample is 41 μV K−1, and its power factor is approximately 6.7 μW m−1 K2. Furthermore, owing to the high plasticity of the foam slurry prior to molding, it can be used to fabricate thermoelectric devices through printing techniques. By employing this approach, a thermoelectric device consisting of nine individual p-type graphite thermoelectric units is printed on the A4 paper. The device produces a temperature difference of 32 K and a thermoelectric potential of 10 mV on a 373 K heating plate. Since both the sample and the paper are flexible, the device can be folded to reduce its size, which broadens the range of potential applications of these thermoelectric materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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34. Site-selective and stochastic spin labelling of neutral water-soluble dietary fibers optimized for electron paramagnetic resonance spectroscopy.
- Author
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Wu, Xiaowen, Boulos, Samy, Yulikov, Maxim, and Nyström, Laura
- Subjects
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ELECTRON paramagnetic resonance spectroscopy , *SPIN labels , *DIETARY fiber , *EINSTEIN-Podolsky-Rosen experiment - Abstract
Use of spin labels to study structures of polymers has been widely spread in polymer science. However, for the studies of neutral water-soluble dietary fibers (DFs), labelling efficiencies in past studies have only been sufficient for application of continuous wave electron paramagnetic resonance spectroscopy (CW-EPR), but still insufficient for some advanced methods such as pulse EPR. Thus, in this paper, two spin labelling strategies, namely, site-selective mono-spin-labelling and stochastic multi-spin-labelling, were examined on linear cereal β-glucan, as well as linearly branched arabinoxylan and galactomannan. The effects of both methods in DF properties were evaluated. For the mono-labelling pathway, labelling efficiency could reach up to 46 %. In the stochastic labelling strategy, a degree of substitution (DS) up to 150 % could be reached, whereas optimized conditions for this strategy were achieved at DS = 3 % to obtain DFs whose bioactivity properties were still preserved while spin labelling efficiency was still sufficient for CW and pulse EPR experiments. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
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35. Irisin, an exercise-induced bioactive peptide beneficial for health promotion during aging process.
- Author
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Zhang, Hu, Wu, Xiaowen, Liang, Jiling, Kirberger, Michael, and Chen, Ning
- Subjects
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PEPTIDES , *IRISIN , *NEUROLOGICAL disorders , *HEALTH promotion , *FUNCTIONAL foods , *ALZHEIMER'S disease , *OXYGEN consumption - Abstract
Irisin is an exercise-induced myokine expressed as a bioactive peptide in multiple tissues and organs, and exercise and cold exposure are the major inducers for its secretion. Irisin presents a decreasing trend with the extension of age and is also closely associated with a wide range of aging-related diseases. Currently, many studies on irisin are being conducted with respect to physiological functions for health promotion, and the prevention, treatment and rehabilitation of chronic diseases, as well as mechanisms associated with improving energy metabolic balance, enhancing cellular homeostasis by optimizing autophagy, promoting mitochondrial quality control, reducing reactive oxygen species (ROS) production, and mitigating inflammatory responses. These diseases include: metabolic diseases (obesity, type 2 diabetes, and bone metabolism); cardiovascular diseases (hypertension, coronary heart disease, cardiomyopathy and stroke); nervous system diseases (Alzheimer's disease, Parkinson's disease, and stroke); and others (cancer and sarcopenia). Although the current studies on irisin are relatively extensive, some studies have produced unexplained experimental results. This article introduces an overview of the generation, secretion, and tissue distribution, of irisin, and its targeting of tissues or organs for the prevention and treatment of above-mentioned chronic diseases is systematically summarized, with discussion of the underlying molecular mechanisms. This study is expected to improve the understanding of irisin, which may be beneficial to identify novel and effective targets for the screening, diagnosis, or therapy of these chronic diseases, or develop promising interventional strategies, effective drug candidates, functional foods, or exercise mimetics. • Irisin, an exercise-induced myokine, expressed as a bioactive peptide in multiple tissues and organs. • Irisin is beneficial to health promotion through regulating physiological function and pathological progression. • Irisin could be a novel and effective target for the screening, diagnosis, or treatment of aging-related diseases. • Irisin could be an effective drug candidate, functional food, or exercise mimetic. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. Enhanced thermostability of formate dehydrogenase via semi-rational design.
- Author
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Wu, Xiaowen, Jiang, Yingying, Wang, Zengyu, Yu, Xiaobin, Sun, Zhoutong, and Luo, Wei
- Subjects
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THERMAL stability , *ESCHERICHIA coli , *AFFINITY chromatography , *MUTAGENESIS , *AMINO acid residues - Abstract
• A NAD+-dependent formate dehydrogenase was expressed in Escherichia coli. • The comprehensive analysis of enzymatic properties was carried out. • Sequences alignment, homologous modeling and molecular docking were conducted. • A mutant obtained significant improvement in thermostability. An NAD+-dependent formate dehydrogenase from Lodderomyces elongisporus (Le FDH) was expressed in Escherichia coli and then purified by nickel affinity chromatography. The analysis of enzymatic properties showed that the specific activity of Le FDH was much high (16.26 U·mg–1), while the thermal stability may be insufficient for industrial application. To further enhance the thermal stability by semi-rational design, sequences alignment, homologous modeling and molecular dynamic simulations were conducted. As a result, seven non-conserved amino acid residues far from the active center were selected for site-directed mutagenesis. Several mutants as well as a binary mutant displayed improved thermal stability and unreduced specific activity. Then temperature and pH stability, kinetic parameters and specific activity, and structural characteristics of wild-type and mutant Le FDH were compared and evaluated. The variant K21P/K22R exhibited an increased half-life by 211% at 60 °C and a 4.5 °C higher T m than those of wild type, and good stability in alkaline environment. This binary mutant enhances the operational stability of Le FDH in the catalytic reaction and thus improves its potential for application in coenzyme regenerations. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. Biosorption of Eu(III) and U(VI) on Bacillus subtilis: Macroscopic and modeling investigation.
- Author
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Yao, Ting, Wu, Xiaowen, Chen, Xi, Xiao, Yunpeng, Zhang, Yongguo, Zhao, Yuanli, and Li, Fengbo
- Subjects
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SORPTION , *EUROPIUM , *METAL absorption & adsorption , *URANIUM , *BACILLUS subtilis , *PH effect , *CARBOXYL group - Abstract
The biosorption of Eu(III) and U(VI) on Bacillus subtilis ( B. subtilis ) as a function of reaction time, pH, ionic strength, temperature was investigated by macroscopic and modeling techniques. The macroscopic experiments indicated that the biosorption kinetics and isotherms of Eu(III) and U(VI) on B. subtilis can be satisfactorily fitted by pseudo-second-order kinetic model and Langmuir model, respectively. No effect of ionic strength revealed that the inner-sphere surface complexation dominated the biosorption of Eu(III) and U(VI) onto B. subtilis . The maximum sorption capacity of B. subtilis calculated from Langmuir model at pH 4.5 and 298 K was 58.80 and 90.91 mg/g for Eu(III) and U(VI), respectively. According to the surface complexation modeling, the biosorption of Eu(III) and U(VI) on B. subtilis can be simulated by diffuse layer modeling with three inner-sphere surface complexation sites such as phosphoryl, carboxyl and hydroxyl groups. The findings presented herein suggested that B. subtilis is a promising bio-adsorbent for the preconcentration and retardation of radionuclides in the environmental remediation strategy such as permeable reactive barrier. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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38. Electronic structure, elastic and thermal properties of semiconductor GaX (X = , , , ) with zinc blende from first-principles calculation.
- Author
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Luo, Bingcheng, Wu, Xiaowen, and Li, Guowu
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GALLIUM compounds , *SPHALERITE , *ELECTRONIC structure , *SEMICONDUCTORS , *ELASTIC properties of metals , *THERMAL properties of metals , *NUMERICAL calculations - Abstract
The band structure, density of states, elastic properties and thermal properties of semiconductor GaX (X = , , , ) with zinc blende were calculated by using the first principle plane-wave pseudo-potential methods based on density functional theory (DFT). The band structure and density of states for , , and show that GaX compounds are semiconductors with a direct band gap of 1.542, 1.445, 0.34 and 0.257 eV, respectively. The elastic constants and modulus are calculated showing that GaX are mechanically stable and has the largest modulus. The anisotropy factor, internal-strain parameter, shear to bulk modulus and Poisson's ratio are also calculated indicating that GaX exhibit a brittle, anisotropic and plastic character. The dependencies of the Debye temperature, heat capacity, enthalpy, the entropy and free energy on temperature are also investigated. Comparisons with the available experiment and other theoretical calculation show reasonable agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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39. Rational combination of multiple structural groups on regulating nonlinear optical property in hexagonal Ln3MGeS7 polar crystals.
- Author
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Gao, Lihua, Wu, Xiaowen, Xu, Jingjing, Tian, Xinyu, Zhang, Bingbing, and Wu, Kui
- Subjects
- *
SECOND harmonic generation , *OPTICAL properties , *CRYSTALS , *CRYSTAL structure , *NONLINEAR optical materials , *NONLINEAR optics - Abstract
• Y 3 LiGeS 7 and Y 3 Cd 0.5 GeS 7 were successfully synthesized for the first time. • Optical performances of title crystals were systematically investigated. • All of them exhibit large SHG responses with requisite phase-matching behavior. • SHG-density and dipole moment calculation analyze the origin of NLO effect. [Display omitted] Combination of multiple structural groups was developed as one effective method for regulating material property and exploring new nonlinear optical (NLO) crystals. For that reason, four Ln 3 MGeS 7 (Y 3 LiGeS 7 , Y 3 Cd 0.5 GeS 7 , Gd 3 Cd 0.5 GeS 7 and Sm 3 Zn 0.5 GeS 7) crystals with various structural motifs were successfully synthesized and systematically investigated. Note that Y 3 LiGeS 7 and Y 3 Cd 0.5 GeS 7 were firstly synthesized so far. Performance test shows that Ln 3 MGeS 7 compounds exhibit the variable optical bandgaps (1.62–2.33 eV) and good second harmonic generation (SHG) responses (0.7–1.1 × commercial AgGaS 2) with requisite phase-matching behavior, which agree well with the theoretical results (Y 3 LiGeS 7 : Δ n = 0.058 and d 33 = 19.97 pm/V; Y 3 Cd 0.5 GeS 7 : Δ n = 0.055 and d 33 = 20.6 pm/V) and introduction of MIIB (Zn, Cd) atoms into crystal structure is conducive to enlarge the SHG effect. SHG density and dipole-moment calculations indicate that their SHG effects are originated from the major contribution on LnS n units with moderate effect of GeS 4 and MIIBS 6 (Zn, Cd) ligands. Therefore, selecting appropriate functional motifs (LnS n and MIIB) into crystal structure can promote the enhancement of NLO property and further realize the rational design of new promising infrared NLO materials. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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40. Frontispiece: Synthesis and Applications of SAPO‐34 Molecular Sieves.
- Author
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Yu, Wenhe, Wu, Xiaowen, Cheng, Bohao, Tao, Tianyi, Min, Xin, Mi, Ruiyu, Huang, Zhaohui, Fang, Minghao, and Liu, Yangai
- Subjects
- *
MOLECULAR sieves - Abstract
Hierarchical SAPO-34, MTO, nanosized SAPO-34, SAPO-34 molecular sieves, synthesis methods Keywords: hierarchical SAPO-34; MTO; nanosized SAPO-34; SAPO-34 molecular sieves; synthesis methods EN hierarchical SAPO-34 MTO nanosized SAPO-34 SAPO-34 molecular sieves synthesis methods 1 1 1 02/22/22 20220219 NES 220219 The methanol-to-olefins reaction has received considerable interest owing to its importance in converting abundant resources, such as coal, natural gas and biomass, to widely demanded light olefins. SAPO-34, with a CHA topological structure, has high methanol conversion and excellent selectivity for light olefins. [Extracted from the article]
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- 2022
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41. Facile synthesis of camptothecin intercalated layered double hydroxide nanohybrids via a coassembly route.
- Author
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Wu, Xiaowen, Li, Haiping, Song, Shue, Zhang, Renjie, and Hou, Wanguo
- Subjects
- *
CAMPTOTHECIN , *CLATHRATE compounds , *LAYERED double hydroxides , *MOLECULAR self-assembly , *PHARMACEUTICAL chemistry , *CHEMICAL reactions , *ORGANIC synthesis - Abstract
Highlights: [•] Camptothecin intercalated layered double hydroxide (LDH) nanohybrids were successfully synthesized. [•] A coassembly route was used to synthesize these LDH nanohybrids. [•] This route gave short reaction times, mild conditions, and high drug loading. [•] Charge-neutral and poorly water-soluble drugs could be effectively intercalated. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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42. Facile synthesis of deoxycholate intercalated layered double hydroxide nanohybrids via a coassembly process.
- Author
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Wu, Xiaowen, Wang, Shuang, Du, Na, Zhang, Renjie, and Hou, Wanguo
- Subjects
- *
DEOXYCHOLIC acid , *LAYERED double hydroxides , *HYBRID systems , *MOLECULAR self-assembly , *CHEMICAL processes , *ANIONS , *FOURIER transform infrared spectroscopy - Abstract
Abstract: In this paper, we describe a synthesis strategy of deoxycholate (DC) intercalated layered double hydroxide (LDH) nanohybrids via a coassembly method at room temperature. For this strategy, LDH particles were delaminated to well-dispersed 2D nanosheets in formamide, and the resulting LDH nanosheets were then coassembled with DC anions into the DC intercalated LDH (DC-LDH) nanohybrids. The so-synthesized nanohybrids were characterized by XRD, TEM, FT-IR, elemental analyses and TG-DSC. It was found that the loading amount of DC in the nanohybrids could be easily controlled by changing the ratio of DC to LDH. In addition, the nanohybrids have similar characteristics with the DC-LDH nanohybrids synthesized by the hydrothermal method, including their DC loading, crystal structure, morphology and thermal gravimetric behavior. However, this strategy exhibited the advantages of short reaction time and mild experimental conditions compared with the hydrothermal method. [Copyright &y& Elsevier]
- Published
- 2013
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43. Effect of final pyrolysis temperature on the mechanical and thermal properties of carbon foams reinforced by aluminosilicate
- Author
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Wu, Xiaowen, Fang, Minghao, Mei, Lefu, and Luo, Bingcheng
- Subjects
- *
PYROLYSIS , *TEMPERATURE effect , *THERMAL properties of crystals , *MECHANICAL behavior of materials , *FOAMED materials , *ALUMINUM silicates , *MICROSTRUCTURE , *PHENOLIC resins - Abstract
Abstract: Carbon foams with phenolic resin as precursor and aluminosilicate as reinforcement were prepared at different final pyrolysis temperatures. The microstructures, mechanical and thermal properties of the foams were investigated by scanning electron microscopy, mechanical testing and the laser flash method, respectively. The results show that the cells are mainly open with incomplete cell membranes, and the alumninosilicate particles are located in cell walls. The surface of cell openings becomes rougher as the final pyrolysis temperature increases. The ultimate compressive strength increases from 0.45 to 1.74MPa when increasing the final pyrolysis temperature from 1100 to 1550°C. The thermal conductivity ranged from 0.37 to 0.52Wm−1 K−1 at room temperature and decreases with increasing the final pyrolysis temperature. The occurrence of the mullite phase plays a key role in the changes of the mechanical properties and thermal conductivity of the foams. [Copyright &y& Elsevier]
- Published
- 2012
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44. Novel Dual-Site-Binding Neuraminidase Inhibitor from Virtual Screening by Pharmacophore and Molecular Dynamics Methods.
- Author
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Huang, Kun, Wu, Xiaowen, Jiang, Zhengyu, Sun, Haopeng, and You, Qidong
- Abstract
Neuraminidase is a significant anti-influenza target that plays crucial role in virus replication cycle. The discovery of 150-cavity in Group-1 neuraminidase provides us a novel mentality of designing inhibitor which can bind with both conserved site and 150-cavity. In order to discover novel dual-site-binding inhibitors, a 3D chemical-feature-based pharmacophore model was established to cover dual-site in neuraminidase. The dual-site-binding model was consistent in predicting the binding conformation of Group-1 neuraminidase inhibitor and applied for virtual screening of Specs database. Compound 4 (ZINC05790048) that aligned well to the model was selected after multiple filtrations for molecular dynamics simulations, indicating improved binding energy with neuraminidase. It can sever as the lead compound for a novel series of inhibitors. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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45. l-Nipecotic Acid-Porphyrin Derivative: A Chiral Host with Introverted Functionality for Chiral Recognition.
- Author
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Wu, Xiaowen and Starnes, Stephen D.
- Subjects
- *
CHEMICAL derivatives , *PORPHYRINS , *HETEROCYCLIC compounds synthesis , *CHIRALITY , *CARBOXYLATES , *NUCLEAR magnetic resonance spectroscopy , *AMMONIUM salts - Abstract
The synthesis and chiral recognition properties of a porphyrin host with introverted functionality is reported. The host is a hybrid of tetraphenyl zinc porphyrin and the N-phenylamide derivative of (S)-nipecotic acid. The chiral recognition properties of the porphyrin host with chiral carboxylate-containing guests is described. UV/vis and 1H NMR spectroscopic results indicate the host shows enantioselectivity for (S)-mandelate tetrabutyl ammonium salt. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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- View/download PDF
46. Microstructure and electrical resistivity of carbon/carbon composites prepared by thermal gradient chemical vapor infiltration.
- Author
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Wu, Xiaowen, Du, Gaoxiang, Fang, Minghao, and Mei, Lefu
- Subjects
- *
MICROSTRUCTURE , *ELECTRICAL resistivity , *CARBON composites , *SEEPAGE , *POLARIZATION microscopy , *TEMPERATURE effect - Abstract
Carbon/carbon composites were prepared by thermal gradient chemical vapor infiltration with kerosene as precursor. The microstructure and electrical resistivity were examined by polarized light microscopy and low-resistance instrument, respectively. The effects of processing parameters on microstructure as well as the influences of sample density, processing parameters, and needle punch on electrical resistivity of carbon/carbon composites were analyzed. The results show that besides rough laminar, smooth laminar and isotropic pyrocarbon occur at temperatures of 1000°C and 1200°C, respectively. The graphitization degree of composites increases from 16.28% to 63.95% as the heat treatment temperature increases from 2100°C to 2500°C. The electrical resistivity of carbon/carbon composites decreases with increasing heat treatment temperature and sample density but increases as the texture of pyrocarbon varies from rough laminar to smooth laminar. The main mechanism for influencing the electrical resistivity of carbon/carbon composites can be changing carrier concentration, altering grain scattering, or both actions. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
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47. Preparation and characterization of carbon foams derived from aluminosilicate and phenolic resin
- Author
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Wu, Xiaowen, Liu, Yan’gai, Fang, Minghao, Mei, Lefu, and Luo, Bingcheng
- Subjects
- *
FOAM , *PHENOLIC resins , *ALUMINUM silicates , *SCANNING electron microscopes , *MICROSTRUCTURE , *MECHANICAL behavior of materials , *OXIDATION - Abstract
Abstract: Aluminosilicate-reinforced carbon foams have been prepared by chemical foaming with phenolic resin as matrix precursor and aluminosilicate as the additive. The effects of the amount of aluminosilicate used on the microstructure, mechanical properties and oxidation resistance of the carbon foams have been investigated by scanning electronic microscopy, mechanical testing, and oxidation weight loss, respectively. The results show that the amount of aluminosilicate added has a significant influence on the surface roughness and the structure uniformity of carbon foams. The compressive strengths are usually higher than that of the pure carbon foam sample by as much as 60%. The percentage of weight loss of the carbon foams drops with increasing aluminosilicate content up to 11wt%, but then increases. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
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48. Mechanical properties investigation of carbon/carbon composites fabricated by a fast densification process
- Author
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Wu, Xiaowen and Luo, Ruiying
- Subjects
- *
MECHANICAL behavior of materials , *CARBON composites , *FRACTURE mechanics , *MATERIALS testing , *SCANNING electron microscopy , *LAMINAR flow - Abstract
Abstract: Carbon/carbon (C/C) composites were prepared by thermal gradient chemical vapor infiltration with a fast densification rate. The fracture morphology and mechanical properties were examined by scanning electron microscopy and mechanical testing, respectively. The effects of preform type and heat treatment temperature (HTT) on the mechanical properties of C/C composites were analyzed. The results show that the average flexural strength drops from 47.8MPa to 38.6MPa as the HTT increases from 2100°C to 2500°C. C/C composites with felt as preform show brittle fracture and samples with needle-punched felt as reinforcement present obvious pseudoplastic property. The interlaminar shear strength of needle-punched felt reinforced composites is higher than that of sample with felt as preform by 44.26% owing to the needle-punched fiber in the thickness direction. The strength of interfacial bonding plays a key role to mechanical properties and failure behavior of C/C composites. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
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49. Deposition mechanism and microstructure of pyrocarbon prepared by chemical vapor infiltration with kerosene as precursor
- Author
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Wu, Xiaowen, Luo, Ruiying, Zhang, Jincao, Xiang, Qiao, and Ni, Yongfeng
- Subjects
- *
MICROSTRUCTURE , *CARBON composites , *SEEPAGE , *CHEMICAL vapor deposition , *KEROSENE , *SCANNING electron microscopy , *POLARIZATION microscopy , *CHEMICAL kinetics - Abstract
Abstract: Large-size carbon/carbon composites (Φ 450× Φ 230×15mm3) have been produced by chemical vapor infiltration with kerosene as precursor. The microstructure of pyrocarbon was examined by polarized light microscopy and scanning electron microscopy. The infiltration kinetics was analyzed to investigate the infiltration rate limitation by parameters such as temperature. The results show that rough laminar carbon constitutes the majority of the matrix at a medium temperature (about 1100°C), while smooth laminar and isotropic structures occur at temperatures lower than 1000°C and higher than about 1200°C, respectively. The apparent activation energy of kerosene decomposition in the temperature range 900–1200°C is about 125.6kJ/mol. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
50. Kinetics of thermal gradient chemical vapor infiltration of large-size carbon/carbon composites with vaporized kerosene
- Author
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Wu, Xiaowen, Luo, Ruiying, Zhang, Jincao, Li, Qiang, and Ni, Yongfeng
- Subjects
- *
CHEMICAL vapor deposition , *CARBON , *COMPOSITE materials , *DIFFUSION , *KEROSENE , *MICROSTRUCTURE - Abstract
Abstract: Large-size samples of carbon/carbon composites were prepared using thermal gradient chemical vapor infiltration with kerosene precursor at 950, 1020, 1100, 1180 and 1250°C. The temperature gradient, kinetics and density distribution of these samples were studied and the microstructure of pyrolytic carbon was examined by polarized light microscopy. The results show that the initial infiltration rate increased from 5.81 to 21.32gmin−1 by increasing deposition temperature from 950 to 1250°C. The densification kinetics relied on deposition temperature and competition between reaction and diffusion, and the diffusion mechanism transformed from bulk to Knudsen diffusion regime. The calculated apparent activation energy is about 68.2kJmol−1. The temperature range 1020–1100°C is appropriate for fabricating composites with high final bulk density due to high degree of pore filling and the density of sample S3 infiltrated at 1100°C is the highest among all investigated samples. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
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