The effect of through plane pore gradient GDL on the water distribution of PEMFC

The effect of through plane pore gradient of gas diffusion layer (GDL) on the performance of Polymer Electrolyte Membrane Fuel Cell is investigated experimentally. The performance with GDLs having no, medium and high pore gradient are compared at 2 different relative humidity (RH) conditions. The medium pore gradient GDL shows generally the best performance in both RH conditions. The performance difference is analyzed based on the water distribution. The water distribution is measured through the X-ray visualization. The amount of water is reduced with the pore gradient GDL. This change reduces the concentration over-potential, and thereby increases the performance at high RH condition. However, the reduction of liquid water results in dehydration of the membrane at low RH condition. This makes lower performance with high pore gradient. The highest performance is not matched with the highest pore gradient. The effect of pore gradient is distinct when water exists sufficiently.     

The analysis of adhesion force at the interface of gas diffusion layer and channel in polymer electrolyte membrane fuel cell

The adhesion force of water droplet on the gas diffusion layer (GDL) is modeled based on the droplet deformation. The deformed droplet is represented as an ovoid shape. The adhesion force is calculated based on it and verified by the surface tilting experiment. The model predicts the shape of deformed droplet and adhesion force within 30% error, whereas previous models predict adhesion force with error larger than 30%. The modified model is used to compare the adhesion force among 3 types of GDL having pore gradient. The comparison result is well matched with the water distribution in polymer electrolyte membrane fuel cell (PEMFC) and water detachment phenomena at the GDL. High adhesion force makes more water accumulation at the interface of GDL and gas supplying channel. This makes different boundary condition and changes the water distribution in PEMFC.     

Amplitude fluctuations and photon statistics of InGaAsP injection lasers

We experimentally show that the statistical distribution of the light output from an injection laser can be adequately described by the superposition of a coherent electric field and narrow-band Gaussian noise. A technique for measuring these fluctuations in the time domain with a resolution of 120 ps is described. The results for several InGaAsP lasers show that intensity fluctuations in an injection laser are rather large, so that the probability of finding the output below 50 percent of the average power in a 120 ps time interval can be as high as 10^-5.     

Energy optimization of multilevel cache architectures for RISC andCISC processors

In this paper, we present the characterization and design of energy-efficient, on chip cache memories. The characterization of power dissipation in on-chip cache memories reveals that the memory peripheral interface circuits and bit array dissipate comparable power. To optimize performance and power in a processor's cache, a multidivided module (MDM) cache architecture is proposed to conserve energy in the bit array as well as the memory peripheral circuits. Compared to a conventional, nondivided, 16-kB cache, the latency and power of the MDM cache are reduced by a factor of 1.9 and 4.6, respectively. Based on the MDM cache architecture, the energy efficiency of the complete memory hierarchy is analyzed with respect to cache parameters in a multilevel processor cache design. This analysis was conducted by executing the SPECint92 benchmark programs with the miss ratios for reduced instruction set computer (RISC) and complex instruction set computer (CISC) machines     

Glucose-stimulated insulin secretion of various mesenchymal stem cells after insulin-producing cell differentiation

Mesenchymal stem cells (MSCs) are capable of crossing germinative layer borders and are obtainable in high numbers via in vitro cultures. Therefore, many researchers have searched for diverse sources of MSCs. Recently the generation of glucose-responsive insulin-producing cells (IPCs) from MSCs has shown immense potential for the treatment of type 1 diabetes mellitus (T1DM) due to a lack of pancreas donors. In this study, we compared the growth potency of four kinds of MSCs derived from bone marrow, Wharton's jelly, adipose tissue, and the periosteum. In addition, in vitro differentiation of these MSCs into IPCs was also investigated. After 2weeks of IPCs differentiation, we compared the expression of the insulin gene and protein using RT-qPCR and immunofluorescence staining. Only IPCs derived from periosteum-derived progenitor cells (PDPCs) showed a response to glucose concentration. Glucose stimulated insulin secretion was conclusive evidence of the potential functionality of IPCs. Therefore, PDPCs are a promising alternative stem cell source for IPCs differentiation.     

Part I: the influence of serial repitching of Saccharomyces pastorianus on the uptake dynamics of metal ions and fermentable carbohydrates during the fermentation of barley and gluten‐free buckwheat and quinoa wort

Recently, research has been focusing on the use of alternative raw materials for brewing purposes and gluten‐free beer‐like beverages from malted buckwheat and quinoa are of commercial interest. A common commercial process involves the serial repitching of the yeast biomass, but this has not been described using buckwheat and quinoa wort fermentations. Our research studies (Parts I–III) explored the serial repitching of the yeast strain Saccharomyces pastorianus TUM 34/70 on the composition of a barley, buckwheat and quinoa fermentation medium. The present paper focuses on the fermentation performance and the uptake dynamics of metal ions and fermentable carbohydrates. Both pseudocereals showed high variations in all of the attributes examined during successive fermentations. In buckwheat the differences between successive fermentations were similar to those observed with barley, whereas differences in quinoa varied quite significantly from those observed with barley and showed a directional trend, suggesting a general weakening of the yeast from the sixth successive fermentation onward. In particular, the assimilation of the fermentable carbohydrates lessened and metal ion uptake appeared poorly controlled. It was concluded that buckwheat showed good potential for serial repitching of S. pastorianus TUM 34/70, whereas serial repitching of a quinoa wort appeared to be limited to five or six fermentations. Copyright © 2015 The Institute of Brewing & Distilling     

Evaluation of Brining Ingredients and Antimicrobials for Effects on Thermal Destruction of Escherichia coli O157:H7 in a Meat Model System

ABSTRACT: Escherichia coli O157:H7 may become internalized during brine injection of meat. This study evaluated the effect of brining ingredients on E. coli O157:H7 in a meat model system after simulated brining, storage, and cooking. Fresh knuckles (5.3 ± 2.4% fat) or beef shoulder (15.3 ± 2.2% fat) were ground individually, mixed with an 8-strain composite of rifampicin-resistant E. coli O157:H7 (7 log CFU/g) and brining solutions. Treatments included no brining, distilled water, sodium chloride (NaCl, 0.5%), sodium tripolyphosphate (STP, 0.25%), sodium pyrophosphate (SPP, 0.25%), NaCl + STP, NaCl + SPP, NaCl + STP + potassium lactate (PL, 2%), NaCl + STP + sodium diacetate (SD, 0.15%), NaCl + STP + PL + SD, NaCl + STP + lactic acid (0.3%), NaCl + STP + acetic acid (0.3%), NaCl + STP + citric acid (0.3%), NaCl + STP + EDTA (20 mM) + nisin (0.0015%) or pediocin (1000 AU/g), NaCl + STP + sodium metasilicate (0.2%), NaCl + STP + cetylpyridinium chloride (CPC; 0.5%), and NaCl + STP + hops beta acids (0.00055%). Samples (30 g) were analyzed for pH, and total microbial and rifampicin-resistant E. coli O157:H7 (inoculum) populations immediately after mixing, storage (24 h at 4 °C), and cooking to 65 °C. Fat and moisture contents and water activity were measured after storage and cooking only; cooking losses also were determined. The effect of beef type on microbial counts, pH, and water activity was negligible. No reductions in microbial counts were obtained by the brining solutions immediately or after storage, except for samples treated with CPC, which reduced (P < 0.05) pathogen counts after storage by approximately 1 log cycle. Cooking reduced pathogen counts by 1.5 to 2.5 logs, while CPC-treated samples had the lowest (P < 0.05) counts compared to any other treatment. These data may be useful in developing/improving brining recipes for control of E. coli O157:H7 in moisture-enhanced beef products.     

Evidence for Intact Selective Attention in Alzheimer's Disease Patients Using a Location Priming Task.

Researchers examining selective attentional mechanisms in patients with Alzheimer's disease (AD) often report impairment in patients' ability to inhibit irrelevant or distracting information. However, in many studies reporting such failures, researchers used tasks that require semantic processing, which a large body of literature documents to be disrupted in AD. The authors of this study used a spatial location-priming task that minimized semantic processing to examine the phenomena of negative priming and facilitative priming in 13 AD patients and 13 healthy older adults. AD patients demonstrated facilitative and negative priming proportionately equivalent to that of older adults. These findings suggest that both the facilitative and inhibitory mechanisms involved in selective attention are preserved in patients with AD and can be revealed in tasks that minimize semantic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Silicon oxide-planarized single-mode 850-nm VCSELs with TO package for 10 Gb/s data transmission

In this letter, we report on an alternative method to fabricate a high-efficiency planar-type oxide-confined 850-nm vertical-cavity surface-emitting lasers (VCSELs). The planarized process of VCSELs was to use the silicon oxide as the buried layer. As a result, these devices with an oxidized aperture of 3 /spl mu/m in diameter exhibit a single-transverse mode behavior throughout the operation current range. In addition, the static characteristics of VCSELs at 300 K include a threshold current of 0.52mA corresponding to a threshold voltage of 2.2 V, a maximum single transverse-mode light output power of 1.13 mW at 4.5 mA, and an external differential quantum efficiency of 35%. On the other hand, this TO-packaged planar-type 850-nm VCSEL for back-to-back test shows a wide open along with symmetric eye diagram and could also pass the 10 Gb/s mask as operating at 10.3 Gb/s and 4 mA. Furthermore, the VCSEL can still keep the eye diagram open and symmetric after the 66-m multi-mode fiber transmission and has a power penalty of 6.6 dB because of fiber dispersion for 10.3 Gb/s data rate at a bit error rate of 10/sup -11/. These results confirm the excellent high-speed performance of SiO/sub x/-planarized VCSELs as compared to the polyimide-planarized VCSELs.