Free vibration of generally-laminated, shear-deformable, composite rectangular plates using a spline Rayleigh-Ritz method

A Rayleigh-Ritz method is presented for predicting the natural frequencies of flat rectangular laminates which can have arbitrary lay-up. The effects of through-thickness shear deformation are included in the analysis. The displacement field utilises B-spline functions in what has been referred to in earlier work as a B_{k, k−1}-spline Rayleigh-Ritz method and the approach is versatile in the specification of boundary conditions. The results of a number of applications are presented in the form of studies showing the convergence of frequency values with increase in the number of spline sections used. The analysis procedure is seen to have good convergence characteristics when dealing with laminates of thin and thick geometry.     

Geometrically nonlinear analysis of rectangular mindlin plates using the finite strip method

A general finite strip method of analysis is presented for the geometrically nonlinear analysis of laterally loaded, rectangular, isotropic plates. The analysis is based on the use of Mindlin plate theory and therefore includes the effects of transverse shear deformation. The nonlinearity is introduced via the strain-displacement equations and correspondingly the analysis pertains to problems involving moderate displacements but small rotations. The principle of minimum potential energy is used in the development of the strip and the complete plate stiffness equations and the latter equations are solved using the Newton-Raphson method. In numerical applications a particular type of finite strip is used in which all five reference quantities (three displacements and two rotations) are represented by cubic polynomial interpolation across the strip whilst the ends of the strip are simply supported for bending/shearing behaviour and immovable for membrane behaviour. These applications are concerned with uniformly loaded plates of both thin and moderately-thick geometry and detailed presentation is given of both displacement- and force-type quantities.     

Extracellular recordings in the colchicine-lesioned rat dentate gyrus following transplants of fetal dentate gyrus and CA1 hippocampal subfield tissue

Grafts of fetal dentate gyrus (DG) and CA1 hippocampal subfield tissue were extruded into the dentate gyri of adult male Sprague-Dawley rats, 7-10 days after lesioning the granule cells with colchicine (0.06 microliter of 7 mg/ml solution at each of 5 sites/hippocampus). Graft area-host and host-graft area connectivities were investigated 4-6 months post-transplantation by recoding extracellular evoked response in hippocampal slice preparations. Following stimulation of the host mid-molecular layer, evoked field potential responses, showing considerable variation, were recorded in both types of graft. Evoked responses in the lesioned DG without grafts were recorded in very few slices. Stimulation of the area of DG tissue grafts occasionally evoked responses in the host CA3/CA4 and there was no evidence for CA1 graft area-CA3/CA4 connectivity; stimulation of DG and CA1 graft areas occasionally evoked responses in the host CA1. Responses in the area of both DG and CA1 grafts supported short-term potentiation following stimulation of the host mid-molecular layer but only DG graft areas supported long-term potentiation of the population spike amplitude. In the area of both types of transplant a tonic bicuculline-sensitive inhibition was present and paired-pulse stimulation paradigms provided some evidence for inhibition. It is possible that responses recorded within the area of grafted tissue to stimulation of the host are attributable to host-graft connectivity and similarly, responses recorded in the host to stimulation of the area of the graft may be attributable to graft-host connectivity. Only DG graft areas received host inputs which were capable of sustaining a long-term potentiation and establishing efferent contacts with the host CA3/CA4 subfield, suggesting that these would be more likely than CA1 grafts to reinstate normal functional circuitry.     

糖浆脱色阴离子交换树脂再生新方法的研究

研究了采用新型再生剂再生糖浆脱色阴离子树脂的新方法,Ｓａｃｃｈａｒａｔｅ再生剂中Ｃａ＾２＋离子的存使得固着在树脂上的色素在低盐浓度下高质量地洗脱,与传统再生方法相比能够大大改善树脂的性能和脱色效率。     

Efficacy of moderation-oriented cue exposure for problem drinkers: A randomized controlled trial.

The effectiveness of cue exposure following a priming dose was compared with cognitive-behavioral intervention in a community sample of problem drinkers. Participants were randomly associated to 1 of the 2 conditions and received a mean of 5.84 (SD=2.69) sessions. A psychologist blind to treatment condition conducted an 8-month follow-up. Compared with pretreatment levels, significant decreased in alcohol consumption were evidence posttreatment and maintained at follow-up for both groups. Reductions in severity of dependence, impaired control, and alcohol-related problems were also evidence for both groups at follow-up. No differences in outcome associated with initial severity of alcohol dependence were apparent. The results raise the issue of the appropriateness of reserving a goal of controlled drinking for those with relatively mild alcohol problems and low alcohol dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequent Spindle Assembly Errors Require Structural Rearrangement to Complete Meiosis in Zea mays

The success of an organism is contingent upon its ability to faithfully pass on its genetic material. In the meiosis of many species, the process of chromosome segregation requires that bipolar spindles be formed without the aid of dedicated microtubule organizing centers, such as centrosomes. Here, we describe detailed analyses of acentrosomal spindle assembly and disassembly in time-lapse images, from live meiotic cells of Zea mays. Microtubules organized on the nuclear envelope with a perinuclear ring structure until nuclear envelope breakdown, at which point microtubules began bundling into a bipolar form. However, the process and timing of spindle assembly was highly variable, with frequent assembly errors in both meiosis I and II. Approximately 61% of cells formed incorrect spindle morphologies, with the most prevalent being tripolar spindles. The erroneous spindles were actively rearranged to bipolar through a coalescence of poles before proceeding to anaphase. Spindle disassembly occurred as a two-state process with a slow depolymerization, followed by a quick collapse. The results demonstrate that maize meiosis I and II spindle assembly is remarkably fluid in the early assembly stages, but otherwise proceeds through a predictable series of events.     

激光的基本特征是高光子简并度

本文提出了激光基本特征的新观点，认为它可以统一关于在这个问题上的不同看法。     

Study of gas-liquid jet boundaries in a gas-solid fluidized bed

The boundaries of gas-liquid jets formed during the air-assisted injection of liquids into gas-solid fluidized beds have been investigated using a small and a commercial scale fluidized bed and several injection nozzles. Two independent techniques (a triboelectric probe system and a thermal tracer method) have successfully allowed the characterization of the jet angle, of the jet penetration, and of the overall mapping of the jet cavity.The study demonstrated the effects of the nozzle geometrical configuration, of the air-to-liquid mass ratio fed through the nozzles, and of the scale of the fluidized bed on the jet boundaries.Finally, the experimental results obtained in this work confirmed the accuracy of an empirical correlation for jet penetration available in the literature.     

Gas and oil production from waterflood residual oil: effects of wettability and oil spreading characteristics

In the depressurisation of reservoirs already produced to waterflooded residual oil, solution gas is released when the reservoir pressure drops to below the bubble point. This gas becomes mobilised when the critical gas saturation has been reached. Additionally, the oil itself can become mobile from its residual state and can also be produced under suitable physical conditions. The critical gas saturation, the rate of saturation change, and the gas saturation remaining at the end of the depressurisation process (unrecoverable gas) are important parameters in determining the overall economic performance when depressurising a reservoir.In this, and previous work, we are demonstrating that these quantities depend additionally upon other factors which affect the fluid distribution and the rate of gas generation, particularly the surface and interfacial properties. For instance, earlier visual experiments in glass micromodels suggested that wettability and oil spreading coefficient could substantially influence both the value of the critical gas saturation and the growth pattern for the developing gas bubbles, and thus the gas flow. In order to confirm these observations and to provide quantitative data, further experiments in large sintered packs, with different matrix wettability and with oils having different spreading coefficients (e.g. oil spreading onto a gas–water interface), have been carried out and are reported here. These new experiments show that the magnitude of the critical gas saturation for a water-wet system is about the same irrespective of whether the oil is spreading or non-spreading, but it is much higher than for the oil-wet case. In addition, oil is also produced but the rate of production is dependent upon the rock wettability and the oil characteristics. We find that in a water-wet medium, for spreading oils, the physical form of the oil becomes transformed from being immobile ganglia into mobile oil films, which can then be transported by the gas. For non-spreading oils, oil has to be pushed out by the gas as discontinuous ganglia so less is oil produced. In contrast, in an oil-wet system, the oil phase already exists as a continuous film on the surface of the solid so that the generation of gas effectively expands the oil phase, enabling the oil to be produced in larger quantities even at lower gas saturations.These new experiments give further evidence that rock wettability has an important influence on the performance of gas production from residual oil. Additionally, significant amounts of oil may be recovered after waterflooding from the residual condition, which could have a beneficial impact on the economics of the depressurisation.