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排序方式: 共有280条查询结果,搜索用时 15 毫秒
1.
Raquel Cano Jos L. Prez Liss Angarita Dvila ngel Ortega Yosselin Gmez Nereida Josefina Valero-Cedeo Heliana Parra Alexander Manzano Teresa Isabel Vliz Castro María P. Díaz Albornoz Gabriel Cano Joselyn Rojas-Quintero Maricarmen Chacín Valmore Bermúdez 《International journal of molecular sciences》2021,22(9)
Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required. 相似文献
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3.
Margarida Taborda Duarte H. Y. Liu S. Q. Kou P. -A. Lindqvist K. Miskovsky 《Journal of Materials Engineering and Performance》2005,14(1):104-111
The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover,
the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept
that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a
topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is
performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling
of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical
density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull.
It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when
compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the
most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure.
This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of
the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution
of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling,
characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences
in the mechanical behavior obtained in testing several specimens. 相似文献
4.
Maria del Rosario Martínez-Macias Rocio Janeth Aguilar-Ruiz Omar Nateras-Ramírez Dalia Isabel Sánchez-Machado Jaime López-Cervantes Germán Eduardo Dévora-Isiordia Jesús Álvarez-Sánchez Nidia Josefina Ríos-Vázquez 《Journal of the American Oil Chemists' Society》2021,98(10):993-1000
Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m−2 s−1, yielding 3.5 × 108 cells ml−1, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m−2 s−1 with 1.7 × 108 cells ml−1. The highest total lipid contents (% g lipid × g dry biomass−1) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m−2 s−1 and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m−2 s−1, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m−2 s−1) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m−2 s−1, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m−2 s−1 contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%). 相似文献
5.
Juan Manuel González Calleros Josefina Guerrero García Jean Vanderdonckt 《Universal Access in the Information Society》2013,12(4):387-401
The need for accessibility evaluation tools is motivated by several endogenous and exogenous reasons coming from the end user (the designer and the developer) and companies releasing information systems. Existing evaluation tools mainly concentrate on examining the code of Web pages: Web pages more and more frequently contain non-HTML parts that entirely escape from being treated by existing techniques. This is the case of the advanced human–machine interface (AHMI), a piece of software programmed in C/C++, used for controlling the advanced flight management system in the aircraft cockpit. Studying this new user interface (UI) requires a structured approach to evaluate and validate AHMI designs. The goal in this work is to develop an evaluation tool to automate the process of evaluating the AHMI. The method addresses: support of multiple bases of guidelines (accessibility or usability or both) on-demand (partial or total evaluation), with different levels of details (a presentation for developers and for those responsible for certifying accessibility). The method goes a step toward the automatic evaluation of UI containing non-HTML parts. 相似文献
6.
Karlsson H Mörtstedt H Lindqvist H Tagesson C Lindahl M 《Proteomics. Clinical applications》2009,3(6):663-671
Although obesity and high levels of low-density lipoprotein (LDL) are well-known risk factors for cardiovascular disease, the precise role(s) of different LDL constituents in obesity has not been explored. In the present study, we compared the LDL proteome of healthy control adults (body mass index<25) and obese subjects (body mass index>30). LDL was isolated by density-gradient ultracentrifugation and proteins were separated with 2-D PAGE, quantified, and identified by peptide mass fingerprinting using MALDI-TOF MS. A new LDL-associated protein was identified as transthyretin and found to be significantly more abundant in LDL from the obese subjects. In addition, LDL from the obese subjects contained relatively more α(1) -antitrypsin, apo J, apo C-II, than LDL from controls, and also more of an acidic isoform (pI/Mr; 5.2/23 100) of apo A-I. On the other hand, the relative amounts of apo A-IV and the major isoform of apo A-I (pI/Mr; 5.3/23 100) were significantly less in LDL from the obese subjects. Apo E was less and non-sialylated apo C-III more abundant in LDL from obese men than control men, while there were no such differences between LDL from obese and control women. These findings illustrate that obesity is not only associated with increased LDL-cholesterol levels but also with alterations in the LDL protein composition. The presence of transthyretin in LDL from obese subjects may reflect over-nutrition and affect the lipid metabolism in obesity. 相似文献
7.
We report the purification and characterization of glucose-1-phosphate cytidylyltransferase, the first of five enzymes committed to biosynthesis of CDP-D-abequose from Salmonella enterica strain LT2. The purification was greatly facilitated by using a cloned rfbF gene encoding this enzyme. Pure enzyme was obtained by 64-fold enrichment in three chromatography steps. The NH2-terminal sequence of the purified enzyme was in agreement with the sequence predicted from the nucleotide sequence of the rfbF gene. The SDS-polyacrylamide gel electrophoresis estimated subunit M(r) of 31,000 agrees well with the M(r) of 29,035 calculated from the amino acid composition deduced from the nucleotide sequence of the rfbF gene. The glucose-1-phosphate cytidylyltransferase catalyzes a reversible bimolecular group transfer reaction and steady-state kinetic measurements, including product inhibition patterns, indicate that this reaction proceeds by a "ping-pong" type of mechanism. The Km values for CTP, alpha-D-glucose 1-phosphate, CDP-D-glucose, and pyrophosphate are 0.28, 0.64, 0.11, and 1.89 mM, respectively. 相似文献
8.
Lindqvist B 《Applied ergonomics》1993,24(3):174-180
In the process of tightening a joint, the angled nutrunner acts on the operator with a torque reaction in the final stages of the tightening sequence. In the following series of experiments, the torque reaction of a machine acting on various joints is studied. A distinctive feature of the torque reaction is that the handle of the angled nutrunner causes a rapid displacement. The amplitude and time aspect of this displacement depend on the stiffness of the joint (whether it is hard or soft), and the movement of the handle depends on how the operator is holding it. How the operator responds to the torque reaction depends upon, among other things, the displacement amplitude as well as the torque level of the machine. Because of this, the displacement amplitude can be used as a measure of the operator's discomfort. 相似文献
9.
Josefina Sierra-Santibáñez 《Annals of Mathematics and Artificial Intelligence》2003,39(1-2):61-100
We study the declarative formalization of reasoning strategies by presenting declarative formalizations of: (1) the SNLP algorithm for nonlinear planning, and (2) a particular algorithm for blocks world nonlinear planning proposed in this paper. The formal models of a heuristic forward chaining planner, which can take advantage of declarative formalizations of action selection strategies, and of a reasoning strategy based planner, which can use declarative formalizations of reasoning strategies, are proposed. The effectiveness of these systems is studied from formal and empirical points of view. Empirical results showing how the use of declarative formalizations of reasoning strategies can reduce the amount of search required for solving planning problems (with respect to state of the art planning systems) are presented. 相似文献
10.
Plaza-Cazón Josefina González Esteban Donati Edgardo Rubén 《Mine Water and the Environment》2021,40(4):994-1002
Mine Water and the Environment - The role of iron- and sulfur- oxidizing microorganisms in the generation of acid mine drainage (AMD) from sulfide ores and tailings is widely recognized. The... 相似文献