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排序方式: 共有209条查询结果,搜索用时 31 毫秒
71.
Tryndyak VP Han T Muskhelishvili L Fuscoe JC Ross SA Beland FA Pogribny IP 《Molecular nutrition & food research》2011,55(3):411-418
Scope : A methyl‐deficient diet induces liver injury similar to human nonalcoholic steatohepatitis, one of the main risk factors for the development of hepatocellular carcinoma. Previous studies have demonstrated that this diet perturbs DNA methylation by causing a profound loss of global cytosine methylation, predominantly at heavily methylated repetitive sequences. However, whether methyl deficiency affects the methylation status of gene promoters has not been explored. Methods and results : Mouse gene expression and CpG island microarrays were used to characterize the gene expression and CpG island methylation profiles in the livers of C57BL/6J mice fed a methyl‐deficient diet. We detected 164 genes that were differentially expressed and exhibited an inverse relationship between the gene expression and the extent of CpG island methylation. Furthermore, these genes were associated with altered lipid and glucose metabolism, DNA damage and repair, apoptosis, the development of fibrosis, and liver tissue remodeling. Although there were both increased and decreased levels of CpG island methylation, the number of hypomethylated genes was substantially greater than the number of hypermethylated genes. Conclusion : The results this study demonstrate that pairing methylation profiles with gene expression profiles is a powerful approach to identify dysregulated high‐priority fundamental pathophysiological pathways associated with disease development. 相似文献
72.
Volodymyr Serhiyenko John N. Ivan Nalini Ravishanker Md Saidul Islam 《Accident; analysis and prevention》2014
Uncovering the temporal trend in crash counts provides a good understanding of the context for pedestrian safety. With a rareness of pedestrian crashes it is impossible to investigate monthly temporal effects with an individual segment/intersection level data, thus the time dependence should be derived from the aggregated level data. Most previous studies have used annual data to investigate the differences in pedestrian crashes between different regions or countries in a given year, and/or to look at time trends of fatal pedestrian injuries annually. Use of annual data unfortunately does not provide sufficient information on patterns in time trends or seasonal effects. This paper describes statistical methods uncovering patterns in monthly pedestrian crashes aggregated on urban roads in Connecticut from January 1995 to December 2009. We investigate the temporal behavior of injury severity levels, including fatal (K), severe injury (A), evident minor injury (B), and non-evident possible injury and property damage only (C and O), as proportions of all pedestrian crashes in each month, taking into consideration effects of time trend, seasonal variations and VMT (vehicle miles traveled). This type of dependent multivariate data is characterized by positive components which sum to one, and occurs in several applications in science and engineering. We describe a dynamic framework with vector autoregressions (VAR) for modeling and predicting compositional time series. Combining these predictions with predictions from a univariate statistical model for total crash counts will then enable us to predict pedestrian crash counts with the different injury severity levels. We compare these predictions with those obtained from fitting separate univariate models to time series of crash counts at each injury severity level. We also show that the dynamic models perform better than the corresponding static models. We implement the Integrated Nested Laplace Approximation (INLA) approach to enable fast Bayesian posterior computation. 相似文献
73.
Michael Bratychak Witold Brostow Volodymyr Donchak 《Materials Research Innovations》2002,5(6):250-256
A series of peroxy oligomers has been synthesized on the basis of pyromellitic dianhydride and tetrachloroanhydride of pyromellitic
acid by condensation with polyethylene glycols and tert-butylhydroperoxide. The resulting oligoesters contain two types of functional groups: carboxylic – which can participate
in ionic reactions and peroxide – able to initiate certain radical processes. Concentrations of these groups depend on the
method of synthesis, the nature of starting monomers, and the molecular mass of polyethylene glycol. Structures of oligoesters
have been determined by IR and 1H-NMR spectroscopy. The oligoesters are able to form three-dimensional networks when heated to 400 K. A mechanism of the network
formation is proposed. These materials can be used as curing agents for unsaturated polyesters and also for epoxy + unsaturated
polyester resin compositions.
Electronic Publication 相似文献
74.
目的提高316L不锈钢表面的耐蚀性和生物活性。方法首先采用激光熔覆技术在316L不锈钢表面制备钛层,然后对钛层表面进行微弧氧化处理,从而在316L不锈钢表面制备出含有Ca、P元素的多孔状陶瓷涂层。利用扫描电子显微镜(Scanning Electron Microscope,SEM)、能谱仪(Energy Dispersive Spectrometer,EDS)、X射线衍射仪(X-Ray Diffraction,XRD)分析了钛层厚度对陶瓷涂层的表面显微形貌、元素含量及物相组成的影响。利用电化学实验、浸泡实验分别测试了涂层在1.5倍SBF溶液中的耐蚀性能和生物活性。结果通过激光熔覆复合微弧氧化能够在316L不锈钢表面制备出多孔状陶瓷涂层。随着钛层厚度的增加,微弧氧化原位生成的陶瓷涂层致密度、厚度也增加。当钛层厚度达到0.4 mm时,微弧氧化后得到的陶瓷涂层完整致密,厚度达到20μm。涂层主要由锐钛矿相Ti O2、金红石相Ti O2组成。极化曲线分析可知,腐蚀电位Ecorr为-0.162 V,腐蚀电流密度降至5.11×10-7 A/cm2。陶瓷涂层在1.5倍SBF中浸泡3天后表面即有羟基磷灰石沉积。结论通过激光熔覆复合微弧氧化在316L不锈钢表面制备的陶瓷涂层在模拟体液环境下具有较好的耐蚀性能,同时也具备良好的生物活性。 相似文献
75.
This article represents the latter advancement in the modeling of diffusion processes in deformable solids. Special attention is given to the development of models for thin-walled shells with both thermal and atomic types of diffusion. Based upon these models, a number of general theorems and principles (i.e., the D'Alembert principle, Hamilton principle, mass forces analogy, Clapeyron theorem, fundamental energy theorem, and reciprocity theorem) are formulated and proved. These theorems allow for developing efficient methods for the solution of relevant boundary-value problems for the shells of this kind. 相似文献
76.
Alberto J. Rosales-Silva Francisco J. Gallegos-Funes Volodymyr I. Ponomaryov 《Journal of Visual Communication and Image Representation》2012,23(1):143-149
This paper presents a novel Fuzzy Directional (FD) Filter for suppression of impulsive noise in colour video sequences. The proposed approach consists in the estimation of fuzzy levels to detect movement and noise presence in the neighbourhood frames, permitting to preserve the edges, fine details and chromaticity characteristics in colour images and video sequences. The new framework has been justified applying commonly used objective criteria, such as, Peak Signal to Noise Ratio (PSNR), Mean Absolute Error (MAE) and Normalized Colour Difference (NCD), as well subjective perception by human viewer showing better performance in comparison with known methods presented in the literature. 相似文献
77.
Mykhaylo Lototskyy Serge Nyallang Nyamsi Sivakumar Pasupathi Ivar Wærnhus Arild Vik Crina Ilea Volodymyr Yartys 《International Journal of Hydrogen Energy》2018,43(40):18650-18663
In energy systems, multi-generation including co-generation and tri-generation has gained tremendous interest in the recent years as an effective way of waste heat recovery. Solid oxide fuel cells are efficient power plants that not only generate electricity with high energy efficiency but also produce high quality waste heat that can be further used for hot and chilled water production. In this work, we present a concept of combined cooling, heating and power (CCHP) energy system which uses solar power as a primary energy source and utilizes a reversible solid oxide fuel cell (R-SOFC) for producing hydrogen and generating electricity in the electrolyser (SOEC) and fuel cell (SOFC) modes, respectively. The system uses “high temperature” metal hydride (MH) for storage of both hydrogen and heat, as well as “low temperature” MH's for the additional heat management, including hot water supply, residential heating during winter time, or cooling/air conditioning during summer time.The work presents evaluation of energy balances of the system components, as well as heat-and-mass transfer modelling of MH beds in metal hydride hydrogen and heat storage system (MHHS; MgH2), MH hydrogen compressor (MHHC; AB5; A = La + Mm, BNi + Co + Al + Mn) and MH heat pump (MHHP; AB2; A = Ti + Zr, BMn + Cr + Ni + Fe). A case study of a 3 kWe R-SOFC is analysed and discussed. The results showed that the energy efficiencies are 69.4 and 72.4% in electrolyser and fuel cell modes, respectively. The round-trip COP's of metal hydride heat management system (MHHC + MHHP) are close to 40% for both heating and cooling outputs. Moreover, the tri-generation leads to an improvement of 36% in round-trip energy efficiency as compared to that of a stand-alone R-SOFC. 相似文献
78.
Roman V. Denys Andrey A. Poletaev Jan Ketil Solberg Boris P. Tarasov Volodymyr A. Yartys 《Acta Materialia》2010,58(7):2510-2519
We have successfully applied a hydrogen metallurgy synthesis to yield LaMg12?x intermetallic at 500 °C. During a vacuum thermal desorption from the LaH3–MgH2 nanocomposite prepared by reactive ball milling in H2, hydrogen desorption from the La dihydride occurred via a mechanism of cooperative phase transformation at temperatures being 400° lower than the desorption from pure LaH2. The crystal structure of the intermetallic was determined by synchrotron X-ray diffraction (SR XRD). The orthorhombic LaMg12?x has a giant unit cell, the volume of which exceeds 8000 Å3. In situ SR XRD studies showed the fine details of the hydrogen desorption process with several parallel and consecutive transformation steps. 相似文献
79.
80.
Denys Pogozhykh Yevgen Posokhov Valeriy Myasoedov Galina Gubina-Vakulyck Tetyana Chumachenko Oleksandr Knigavko Hanna Polikarpova Yuliia Kalashnyk-Vakulenko Ketino Sharashydze Oksana Nakonechna Volodymyr Prokopyuk Anatolii Onishchenko Anton Tkachenko 《International journal of molecular sciences》2021,22(20)
The safety of food additives E407 and E407a has raised concerns in the scientific community. Thus, this study aims to assess the local and systemic toxic effects of the common food additive E407a in rats orally exposed to it for two weeks. Complex evaluations of the effects of semi-refined carrageenan (E407a) on rats upon oral exposure were performed. Local effects of E407a on the intestine were analyzed using routine histological stains and CD68 immunostaining. Furthermore, circulating levels of inflammatory markers were assessed. A fluorescent probe O1O (2- (2′-OH-phenyl)-5-phenyl-1,3-oxazole) was used for evaluating the state of leukocyte cell membranes. Cell death modes of leukocytes were analyzed by flow cytometry using Annexin V and 7-aminoactinomycin D staining. Oral administration of the common food additive E407a was found to be associated with altered small and large intestinal morphology, infiltration of the lamina propria in the small intestine with macrophages (CD68+ cells), high systemic levels of inflammation markers, and changes in the lipid order of the phospholipid bilayer in the cell membranes of leukocytes, alongside the activation of their apoptosis. Our findings suggest that oral exposure to E407a through rats results in the development of intestinal inflammation. 相似文献