X-ray computed tomography of a gas-sparged stirred-tank reactor

X-ray computed tomography (CT) is used to explore the differences in gas dispersion in a stirred-tank reactor (STR) for different operating conditions by varying the impeller speed and gas flow rate. X-ray imaging has been carried out in a 0.21 m ID acrylic STR equipped with a nylon Rushton-type impeller. From the CT images, major differences in local gas holdup are observed for different operating conditions. Completely dispersed conditions have a relatively uniform holdup profile while flooded conditions show a high gas holdup near the impeller shaft. The high resolution of the X-ray system allowed fine details such as recirculation regions behind the baffles to be visualized.     

Feasibility of Manufacturing A Solid Dosage Form Using A Liquid Nonvolatile Drug Carrier: A Physico-Chemical Characterization

Experiments were performed to determine the formulation and manufacturing feasibility of three model solid capsule formulations using a spray-on liquid drug carrier. Methylparaben was used as a model low-dose drug in the liquid drug carrier. Formulations containing different amounts of liquid drug carrier were successfully encapsulated on the H&K 400 capsule filling machine. The formulations contained varying ratios of liquid (methylparaben-propylene carbonate solution) to solid (compressible sugar, NF), which ranged from 10.0 - 20.0 μL/450 mg. Physical characteristics (i.e. weight variation, dissolution, etc.) of the filled capsules were evaluated. The 20.0 μL liquid/450 mg solid ratio was found to be the best hard gelatin capsule formulation based upon its rapid dissolution profile and was equivalent to all other formulations tested with respect to weight variation and content uniformity.     

MHz-rate nitric oxide planar laser-induced fluorescence imaging in a Mach 10 hypersonic wind tunnel

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging at repetition rates as high as 1 MHz is demonstrated in the NASA Langley 31 in. Mach 10 hypersonic wind tunnel. Approximately 200 time-correlated image sequences of between 10 and 20 individual frames were obtained over eight days of wind tunnel testing spanning two entries in March and September of 2009. The image sequences presented were obtained from the boundary layer of a 20° flat plate model, in which transition was induced using a variety of different shaped protuberances, including a cylinder and a triangle. The high-speed image sequences captured a variety of laminar and transitional flow phenomena, ranging from mostly laminar flow, typically at a lower Reynolds number and/or in the near wall region of the model, to highly transitional flow in which the temporal evolution and progression of characteristic streak instabilities and/or corkscrew-shaped vortices could be clearly identified.     

从设计到建造——清华大学建造设计实验

建造是建筑设计的原点、创意源泉和重要内容。欧美和我国建筑院校的建造设计是将设计拉回到我们的双手、双眼对材料、连接、表现的基本体验和把握中,强调从建造到设计、从做到学的工匠式的感悟和创造。清华大学建筑学院的建造设计教学正是基于这一理念的实验探索。     

Interpenetrated Gel Polymer Binder for High‐Performance Silicon Anodes in Lithium‐ion Batteries

Silicon has attracted ever‐increasing attention as a high‐capacity anode material in Li‐ion batteries owing to its extremely high theoretical capacity. However, practical application of silicon anodes is seriously hindered by its fast capacity fading as a result of huge volume changes during the charge/discharge process. Here, an interpenetrated gel polymer binder for high‐performance silicon anodes is created through in‐situ crosslinking of water‐soluble poly(acrylic acid) (PAA) and polyvinyl alcohol (PVA) precursors. This gel polymer binder with deformable polymer network and strong adhesion on silicon particles can effectively accommodate the large volume change of silicon anodes upon lithiation/delithiation, leading to an excellent cycling stability and high Coulombic efficiency even at high current densities. Moreover, high areal capacity of ～4.3 mAh/cm² is achieved based on the silicon anode using the gel PAA–PVA polymer binder with a high mass loading. In view of simplicity in using the water soluble gel polymer binder, it is believed that this novel binder has a great potential to be used for high capacity silicon anodes in next generation Li‐ion batteries, as well as for other electrode materials with large volume change during cycling.     

Happy affect and smiling: Is their relation moderated by interpersonal power?

Three studies examined the hypothesis that the relation between self-rated happy affect and overall smiling during dyadic interactions is moderated by one's relative power. In all 3 studies, interpersonal power was experimentally manipulated, and smiling and self-reported happy affect were measured during and after the interaction, respectively. Happy affect was positively correlated with overall smiling for both low-power and high-power participants. Moreover, the correlations for both low- and high-power participants were comparable to those found when power roles were not unequal or made salient, based on analysis of the present studies as well as comparison with the previously published literature. Happy affect and overall smiling had a positive relation that was not moderated by interpersonal power. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Induction of long-term receptive field plasticity in the auditory cortex of the waking guinea pig by stimulation of the nucleus basalis.

Learning induces neuronal receptive field (RF) plasticity in primary auditory cortex. This plasticity constitutes physiological memory as it is associative, highly specific, discriminative, develops rapidly, and is retained indefinitely. This study examined whether pairing a tone with activation of the nucleus basalis (NB) could induce RF plasticity in the waking guinea pig and, if so, whether it could be retained for 24 hrs. Subjects received 40 trials of a single frequency paired with electrical stimulation of the NB at tone offset. The physiological effectiveness of NB stimulation was assessed later while subjects were anesthetized with urethane by noting whether stimulation produced cortical desynchronization. Subjects in which NB stimulation was effective did develop RF plasticity and this was retained for 24 hrs. Thus, activation of the NB during normal learning may be sufficient to induce enduring physiological memory in auditory cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transient diffusion and reaction of ions in an electrostatic double-layer: Application to the response of potentiometric electrodes

The transport equations for unsteady diffusion and simultaneous chemical reaction in an electrostatic double-layer in series with a mass transfer boundary layer have been solved. The results are presented in terms of the transient response of a potentiometric electrode, and show hysteresis and non-first-order behavior associated with the transport phenomena in the double-layer. The double-layer effects can be reduced and even eliminated in the presence of chemical reaction, which provides an alternate mechanism for ion transport within the double-layer.