31,605 research outputs found
Dual Regulating Effect of Shaoyao-Gangcao-Tang on COX- 2 Expression in Acute and Resolution Phases of Carrageenin-Induced Pleurisy in Rats
Purpose: To investigate the effects and potential mechanisms of Shaoyao-Gangcao-Tang (SGT) on acute and resolution phases of carrageenin-induced pleurisy in rats.Methods: To determine the effects of SGT at 2 h, Sprague-Dawley rats received injection of 0.2 ml of 1 % λ-carrageenin into the pleural cavity after treatment with 4.0, 13.3 and 40.0 g/kg SGT for three days. At 2 h after pleurisy induction, exudate volume, total cell number, prostaglandin E2 (PGE2) production and cyclooxygenase-2 (COX-2) protein expression were measured. To determine the effects at 48 h, the rats were treated with SGT at 24, 36 and 46 h after injection of λ-carrageenin into the pleural cavity, and the exudate volume, total cell number, 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) production and COX-2 protein expression were evaluated.Results: At 2 h after pleurisy induction, 13.3 and 40.0 g/kg SGT significantly decreased exudate volume by 34 (p < 0.05) and b 4 0% (p < 0.01), total cell number by 27 (p < 0.05) and 41 % (p < 0.01), PGE2 production by 17 (p < 0.05) and 35 % (p < 0.01), as well as COX-2 protein expression by 21 (p < 0.01) and 43 % (p < 0.01) compared with control group treated with saline. At 48 h after pleurisy induction, 13.3 and 40 g/kg SGT also significantly decreased exudate volume by 36 (p < 0.05) and 55 % (p < 0.01), as well as total cell number by 31 (p < 0.05) and 43 % (p < 0.01), but markedly increased 15d- PGJ2 production by 26 (p < 0.05) and 51 % (p < 0.01), as well as COX-2 protein expression by 50 (p < 0.01) and 100 % (p < 0.01) compared with control group.Conclusion: The findings suggest that SGT has dual regulating effect in acute and resolution phases of inflammation, involving inhibiting acute inflammation through down-regulation of pro-inflammatory mediators, and promoting inflammatory resolution through up-regulation of pro-resolution mediators.Keywords: Shaoyao-Gangcao-Tang, Cyclooxygenase-2, Prostaglandin E2, 15-Deoxy-Δ12,14-PGJ2, Inflammatio
Improved keratinase production for feather degradation by Bacillus licheniformis ZJUEL31410 in submerged cultivation
Optimal medium was used to improve the production of keratinase by Bacillus licheniformis ZJUEL31410, which has a promising application in the transformation of feather into soluble protein. The results of single factor design revealed that the concentration of feather at 20 g/l and the initial pH at value 8 was the best for the production of keratinase and the degradation of feather. Ammonia salt and nitrate salt strongly restricted the production of keratinase and the degradation of feather. Result of Box-Behnken design (BBD) experiment which was used to optimize concentrations of glucose, corn steep flour and K2HPO4 for further improvement of keratinase productivity showed that the optimal medium was composed of glucose (20 g/l), corn steep flour (7.5 g/l), K2HPO4 (1 g/l) and feather (20 g/l). The result of submerged batch cultivation of B. licheniformis ZJUEL31410 in the 5 L fermentor indicated that the optimal medium had the highest keratinase and the degree of feather degradation (DFD) at 54.9 U/ml and 72.4%; both were 5 times more than the basal medium. The degradation of feather was verified by the analysis of scanning electron microscopy (SEM). This study provides a foundation for the production of keratinase and the conversion of feather to soluble protein through submerged fermentation process by B. licheniformis ZJUEL31410.Key words: Bacillus licheniformis ZJUEL31410, keratinase, culture medium, optimization, Box-Behnken design, scanning electron microscopy, feather degradation
Stress distribution during cold compression of a quartz aggregate using synchrotron X-ray diffraction: Observed yielding, damage, and grain crushing
We report new experimental results that quantify the stress distribution within a quartz aggregate during pore collapse and grain crushing. The samples were probed with synchrotron X-ray diffraction as they were compressed in a multianvil deformation apparatus at room temperature from low pressure (tens of megapascal) to pressures of a few gigapascal. In such a material, stress is likely to concentrate at grain-to-grain contacts and vanish where grains are bounded by open porosity. Therefore, internal stress is likely to vary significantly from point to point in such an aggregate, and hence, it is important to understand both the heterogeneity and anisotropy of such variation with respect to the externally applied stress. In our quartz aggregate (grain size of ~4 μm), the measured diffraction peaks broaden asymmetrically at low pressure (tens of megapascal), suggesting that open pores are still a dominant characteristic of grain boundaries. In contrast, a reference sample of novaculite (a highly dense quartz polycrystal, grain size of ~6–9 μm) showed virtually no peak broadening with increasing pressure. In the quartz aggregate, we observed significant deviation in the pressure-volume curves in the range of P = 400–600 MPa. We suggest that this marks the onset of grain crushing (generally denoted as P* in the rock mechanic literature), which is commonly reported to occur in sandstones at pressures of this order, in general agreement with a Hertzian analysis of fracturing at grain contacts
UV-Diagram: A Voronoi Diagram for Uncertain Spatial Databases
published_or_final_versio
On Feedback Vertex Set: New Measure and New Structures
We present a new parameterized algorithm for the {feedback vertex set}
problem ({\sc fvs}) on undirected graphs. We approach the problem by
considering a variation of it, the {disjoint feedback vertex set} problem ({\sc
disjoint-fvs}), which finds a feedback vertex set of size that has no
overlap with a given feedback vertex set of the graph . We develop an
improved kernelization algorithm for {\sc disjoint-fvs} and show that {\sc
disjoint-fvs} can be solved in polynomial time when all vertices in have degrees upper bounded by three. We then propose a new
branch-and-search process on {\sc disjoint-fvs}, and introduce a new
branch-and-search measure. The process effectively reduces a given graph to a
graph on which {\sc disjoint-fvs} becomes polynomial-time solvable, and the new
measure more accurately evaluates the efficiency of the process. These
algorithmic and combinatorial studies enable us to develop an
-time parameterized algorithm for the general {\sc fvs} problem,
improving all previous algorithms for the problem.Comment: Final version, to appear in Algorithmic
Effects of stitching on delamination of satin weave carbon-epoxy laminates under mode I, mode II and mixed-mode I/II loadings
The objective of the present study is to characterize the effect of modified chain stitching on the delamination growth under mixed-mode I/II loading conditions. Delamination toughness under mode I is experimentally determined, for unstitched and stitched laminates, by using untabbed and tabbed double cantilever beam (TDCB) tests. The effect of the reinforcing tabs on mode I toughness is investigated. Stitching improves the energy release rate (ERR) up to 4 times in mode I. Mode II delamination toughness is evaluated in end-notched flexure (ENF) tests. Different geometries of stitched specimens are tested. Crack propagation occurs without any failure of stitching yarns. The final crack length attains the mid-span or it stops before and the specimen breaks in bending. The ERR is initially low and gradually increases with crack length to very high values. The mixedmode delamination behaviour is investigated using a mixed-mode bending (MMB) test. For unstitched specimens, a simple mixed-mode criterion is identified. For stitched specimens, stitching yarns do not break during 25% of mode I ratio tests and the ERR increase is relatively small compared to unstitched values. For 70% and 50% of mode I ratios, failures of yarns are observed during crack propagation and tests are able to capture correctly the effect of the stitching: it clearly improves the ERR for these two mixed modes, as much as threefold
Recommended from our members
De-pollution efficacy of photocatalytic roofing granules
Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abatement capacity of TiO2-coated granules used in roofing products was evaluated for commercial product development. A laboratory test chamber and ancillary setup were built following conditions prescribed by ISO Standard 22197-1. It was validated by exposing reference P25-coated aluminum plates to a 3 L min−1 air flow enriched in 1 ppm NO under UVA irradiation (360 nm, 11.5 W m−2). We characterized prototype granule-surfaced asphalt shingles and loose granules prepared with different TiO2 loadings and post-treatment formulations. Tests performed at surface temperatures of 25 and 60 °C showed that NOx abatement was more effective at the higher temperature. Preliminary tests explored the use of 1 ppm NO2 and of 1 ppm and 0.3 ppm NO/NO2 mixtures. Specimens were aged in a laboratory accelerated weathering apparatus, and by exposure to the outdoor environment over periods that included dry and rainy seasons. Laboratory aging led to higher NO removal and NO2 formation rates, and the same catalyst activation was observed after field exposure with frequent precipitation. However, exposure during the dry season reduced the performance. This inactivation was mitigated by cleaning the surface of field-exposed specimens. Doubling the TiO2 loading led to a 50–150% increase in NO removal and NOx deposition rates. Application of different post-treatment coatings decreased NO removal rates (21–35%) and NOx deposition rates (26–74%) with respect to untreated granules. The mass balance of nitrogenated species was assessed by extracting granules after UV exposure in a 1 ppm NO-enriched atmosphere
Slow cooling and efficient extraction of C-exciton hot carriers in MoS2 monolayer
In emerging optoelectronic applications, such as water photolysis, exciton fission and novel photovoltaics involving low-dimensional nanomaterials, hot-carrier relaxation and extraction mechanisms play an indispensable and intriguing role in their photo-electron conversion processes. Two-dimensional transition metal dichalcogenides have attracted much attention in above fields recently; however, insight into the relaxation mechanism of hot electron-hole pairs in the band nesting region denoted as C-excitons, remains elusive. Using MoS2 monolayers as a model two-dimensional transition metal dichalcogenide system, here we report a slower hot-carrier cooling for C-excitons, in comparison with band-edge excitons. We deduce that this effect arises from the favourable band alignment and transient excited-state Coulomb environment, rather than solely on quantum confinement in two-dimension systems. We identify the screening-sensitive bandgap renormalization for MoS2 monolayer/graphene heterostructures, and confirm the initial hot-carrier extraction for the C-exciton state with an unprecedented efficiency of 80%, accompanied by a twofold reduction in the exciton binding energy
Observation of ion gettering effect in high temperature superconducting oxide material
Ion gettering effect has been observed in high-temperature superconducting YBa2Cu3O7 material. Silicon ions were implanted into the material and subsequent high-temperature annealing produced ion movement from a low concentration region to a higher concentration region where the damage of the crystal structure is severe. This gettering effect could be used to make a superconductor-nonsuperconductor-superconductor trilayer structure within a single YBCO film.published_or_final_versio
- …