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91.
Barbara P. Atshaves Avery L. McIntosh Stephen M. Storey Kerstin K. Landrock Ann B. Kier Friedhelm Schroeder 《Lipids》2010,45(2):97-110
Since liver fatty acid binding protein (L-FABP) facilitates uptake/oxidation of long-chain fatty acids in cultured transfected
cells and primary hepatocytes, loss of L-FABP was expected to exacerbate weight gain and/or obesity in response to high dietary
fat. Male and female wild-type (WT) and L-FABP gene-ablated mice, pair-fed a defined isocaloric control or high fat diet for
12 weeks, consumed equal amounts of food by weight and kcal. Male WT mice gained weight faster than their female WT counterparts
regardless of diet. L-FABP gene ablation enhanced weight gain more in female than male mice—an effect exacerbated by high
fat diet. Dual emission X-ray absorptiometry revealed high-fat fed male and female WT mice gained mostly fat tissue mass (FTM).
L-FABP gene ablation increased FTM in female, but not male, mice—an effect also exacerbated by high fat diet. Concomitantly,
L-FABP gene ablation decreased serum β-hydroxybutyrate in male and female mice fed the control diet and, even more so, on
the high-fat diet. Thus, L-FABP gene ablation decreased fat oxidation and sensitized all mice to weight gain as whole body
FTM and LTM—with the most gain observed in FTM of control vs high-fat fed female L-FABP null mice. Taken together, these results
indicate loss of L-FABP exacerbates weight gain and/or obesity in response to high dietary fat. 相似文献
92.
The unique properties of gold nanoparticles have stimulated the increasing interest in the application of GNPs in interfacing
biological recognition events with signal transduction and in designing biosensing devices exhibiting novel functions. The
optical properties of GNPs provide wide range opportunities for construction optical biosensors. The excellent biocompatibility,
conductivity, catalytic properties and high surface-to-volume ratio and high density of GNPs facilitate extensive application
of GNPs in construction of electrochemical and piezoelectric biosensors with enhanced analytical performance with respect
to other biosensor designs. In this article, the recent advances in construction of GNP-based optical, electrochemical and
piezoelectric biosensors are reviewed, and some illustrative examples given, with a focus on the roles GNPs play in the biosensing
process and the mechanism of GNPs for improving the analytical performances. Finally, the review concludes with an outline
of present and future research for the real-world applications. 相似文献
93.
Philip Weyrauch Erika Pawlowsky-Reusing Dörthe von Seggern Kai Schroeder 《Water research》2010,44(15):4451-4462
The present study examines the contribution of combined sewer overflows (CSO) to loads and concentrations of trace contaminants in receiving surface water. A simple method to assess the ratio of CSO to wastewater treatment plant (WWTP) effluents was applied to the urban River Spree in Berlin, Germany. The assessment indicated that annual loads are dominated by CSO for substances with removal in WWTP above ∼95%. Moreover, it showed that substances with high removal in WWTP can lead to concentration peaks in the river during CSO events. The calculated results could be verified based on eight years of monitoring data from the River Spree, collected between 2000 and 2007. Substances that are well removed in WWTP such as NTA (nitrilotriacetic acid) were found to occur in significantly increased concentration during CSO, while the concentration of substances that are poorly removable in WWTP such as EDTA (ethylenediaminetetraacetic acid) decreased in CSO-influenced samples due to dilution effects. The overall results indicate the potential importance of the CSO pathway of well-removable sewage-based trace contaminants to rivers. In particular, high concentrations during CSO events may be relevant for aquatic organisms. Given the results, it is suggested to include well-removable, sewage-based trace contaminants, a substance group often neglected in the past, in future studies on urban rivers in case of combined sewer systems. The presented methodology is suggested for a first assessment, since it is based solely on urban drainage data, which is available in most cities. 相似文献
94.
Ebinghaus R Kock HH Temme C Einax JW Lowe AG Richter A Burrows JP Schroeder WH 《Environmental science & technology》2002,36(6):1238-1244
Unlike other heavy metals that are inherently associated with atmospheric aerosols, mercury in ambient air exists predominantly in the gaseous elemental form. Because of its prolonged atmospheric residence time, elemental mercury vapor is distributed on a global scale. Recently, Canadian researchers have discovered that total gaseous mercury levels in the lower tropospheric boundary layer in the Canadian Arctic are often significantly depleted during the months after polar sunrise. A possible explanation may involve oxidation of elemental mercury, followed by adsorption and deposition of the oxidized form, leading to an increased input of atmospheric mercury into the Arctic ecosystem. Here we present the first continuous high-time-resolution measurements of total gaseous mercury in the Antarctic covering a 12-month period between January 2000 and January 2001 at the German Antarctic research station Neumayer (70 degrees 39' S, 8 degrees 15' W). We report that mercury depletion events also occur in the Antarctic after polar sunrise and compare our measurements with a data setfrom Alert, Nunavut, Canada. We also present indications that BrO radicals and ozone play a key role in the boundary-layer chemistry during springtime mercury depletion events in the Antarctic troposphere. 相似文献
95.
Tibor Goda Káeroly Váradi Klaus Friedrich Hermann Giertzsch 《Journal of Materials Science》2002,37(8):1575-1583
FE micro-models have been developed in order to determine contact, stress and strain conditions produced by a steel asperity sliding on the surface of a normally oriented fibre-reinforced polymer composite. A displacement coupling technique was introduced to model a micro-environment as part of a macro-environment and to get more realistic simulation results about the failure conditions in the composite structure, in comparison to the so far widely applied anisotropic analytical or numerical macro-models. On the basis of the results, conclusions may be drawn for the possible wear mechanisms of the fibre-reinforced polymer composite. Stress results in the vicinity of the fibers in the contact area show high shear loading of the matrix leading to the formation of stretched-out matrix wear debris. In addition, high repeated compression-tension stresses at the fibre/matrix interface near the surface can lead to fibre debonding phenomena. Considering the fibre ends in the contact region, high compression stresses at their rear edges can produce fibre cracking features. To study the wear mechanisms experimentally, a single asperity scratch test was also performed showing shear failure events of the polymer matrix, fibre/matrix debonding and fibre cracking effects, as expected from the modelling studies. 相似文献
96.
Chen Edith; Hermann Cathy; Rodgers Denise; Oliver-Welker Tina; Strunk Robert C. 《Canadian Metallurgical Quarterly》2006,25(3):389
This study tested the relationship of anxiety and asthma severity to symptom perception. Eighty-six children diagnosed with mild or moderate asthma had symptom perception and pulmonary function measured throughout methacholine challenge (to induce bronchoconstriction). Higher trait anxiety was associated with heightened symptom perception (controlling for pulmonary function) at baseline. Greater asthma severity was associated with blunted symptom perception (controlling for pulmonary function) at the end of methacholine challenge and with a slower rate of increase in symptom perception across methacholine challenge. These results suggest that anxiety plays a role when children's symptoms are mild, whereas medical variables such as severity play a role in perception of changes in asthma symptomatology as bronchoconstriction worsens. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
97.
Photonic crystals with a complete bandgap can stop the propagation of light of a certain frequency in all directions. We introduce double‐inverse‐opal photonic crystals (DIOPCs) as a new kind of optical switch. In the DIOPC, a movable, weakly scattering sphere is embedded within each pore of the inverse‐opal photonic crystal lattice. Switching between a diffusive reflector and a photonic crystal environment is experimentally demonstrated. Theory shows that a complete bandgap can be realized that can be opened or closed by moving the spheres. This functionality opens up new possibilities for the control of light emission and propagation. The close link and interaction between the chemical synthesis and the computational design and analysis underlines the interdisciplinary focus of this report. 相似文献
98.
Radiometric correction of multi-temporal Landsat data for characterization of early successional forest patterns in western Oregon 总被引:2,自引:0,他引:2
Detecting and characterizing continuous changes in early forest succession using multi-temporal satellite imagery requires atmospheric correction procedures that are both operationally reliable, and that result in comparable units (e.g., surface reflectance). This paper presents a comparison of five atmospheric correction methods (2 relative, 3 absolute) used to correct a nearly continuous 20-year Landsat TM/ETM+ image data set (19-images) covering western Oregon (path/row 46/29). In theory, full absolute correction of individual images in a time-series should effectively minimize atmospheric effects resulting in a series of images that appears more similar in spectral response than the same set of uncorrected images. Contradicting this theory, evidence is presented that demonstrates how absolute correction methods such as Second Simulation of the Satellite Signal in the Solar Spectrum (6 s), Modified Dense Dark Vegetation (MDDV), and Dark Object Subtraction (DOS) actually make images in a time-series somewhat less spectrally similar to one another. Since the development of meaningful spectral reflectance trajectories is more dependant on consistent measurement of surface reflectance rather than on accurate estimation of true surface reflectance, correction using image pairs is also tested. The relative methods tested are variants of an approach referred to as “absolute-normalization”, which matches images in a time-series to an atmospherically corrected reference image using pseudo-invariant features and reduced major axis (RMA) regression. An advantage of “absolute-normalization” is that all images in the time-series are converted to units of surface reflectance while simultaneously being corrected for atmospheric effects. Of the two relative correction methods used for “absolute-normalization”, the first employed an automated ordination algorithm called multivariate alteration detection (MAD) to statistically locate pseudo-invariant pixels between each subject and reference image, while the second used analyst selected pseudo-invariant features (PIF) common to the entire image set. Overall, relative correction employed in the “absolute-normalization” context produced the most consistent temporal reflectance response, with the automated MAD algorithm performing equally as well as the handpicked PIFs. Although both relative methods performed nearly equally in terms of observed errors, several reasons emerged for preferring the MAD algorithm. The paper concludes by demonstrating how “absolute-normalization” improves (i.e., reduces scatter in) spectral reflectance trajectory models used for characterizing patterns of early forest succession. 相似文献
99.
In this paper, we develop the notion of fuzzy unification and incorporate it into a novel fuzzy argumentation framework for extended logic programming. We make the following contributions: The argumentation framework is defined by a declarative bottom-up fixpoint semantics and an equivalent goal-directed top-down proofprocedure for extended logic programming. Our framework allows one to represent positive and explicitly negative knowledge, as well as uncertainty. Both concepts are used in agent communication languages such as KQML and FIPA ACL. One source of uncertainty in open systems stems from mismatches in parameter and predicate names and missing parameters. To this end, we conservatively extend classical unification and develop fuzzy unification based on normalised edit distance over trees. 相似文献
100.
Although fatty acid-binding proteins (FABP) differentially affect fatty acid uptake, nothing is known regarding their role(s)
in determining cellular phospholipid levels and phospholipid fatty acid composition. The effects of liver (L)- and intestinal
(I)-FABP expression on these parameters were determined using stably transfected L-cells. Expression of L- and I-FABP increased
cellular total phospholipid mass (nmol/mg protein) 1.7- and 1.3-fold relative to controls, respectively. L-FABP expression
increased the masses of choline glycerophospholipids (ChoGpl) 1.5-fold, phosphatidylserine (PtdSer) 5.6-fold, ethanolamine
glycerophospholipids 1.4-fold, sphingomyelin 1.7-fold, and phosphatidylinositol 2.6-fold. In contrast, I-FABP expression only
increased the masses of ChoGpl and PtdSer, 1.2- and 3.1-fold, respectively. Surprisingly, both L- and I-FABP expression increased
ethanolamine plasmalogen mass 1.6- and 1.1-fold, respectively, while choline plasmalogen mass was increased 2.3- and 1.7-fold,
respectively. The increase in phospholipid levels resulted in dramatic 48 and 33% decreases in the cholesterol-to-phospholipid
ratio in L- and I-FABP expressing cells, respectively. L-FABP expression generally increased polyunsaturated fatty acids,
primarily by increasing 20∶4n−6 and 22∶6n−3, while decreasing 18∶1n−9 and 16∶1n−7. I-FABP expression generally increased only
20∶4n−6 proportions. Hence, expression of both I- and L-FABP differentially affected phospholipid mass, class composition,
and acyl chain composition. Although both proteins enhanced phospholipid synthesis, the effect of L-FABP was much greater,
consistent with previous work suggesting that these two FABP differentially affect lipid metabolism. 相似文献