Photocatalytic hydrogen production under visible light over Cd0.1SnxZn0.9−2xS solid solution photocatalysts

A series of Cd_0.1Sn_xZn_0.9−2xS solid solution was successfully synthesized by hydrothermal method and employed as photocatalyst for photocatalytic hydrogen evolution under visible light irradiation. The structures, optical properties and morphologies of the solid solutions were studied by X-ray diffraction, diffuse reflectance UV-visible spectroscopy and field emission scanning electron microscopy. From the characterizations, it was confirmed that Sn can form solid solution with Cd_0.1Zn_0.9S and the high crystallinity can be maintained as well. Among all samples, the highest photocatalytic activity was observed on Cd_0.1Sn_0.01Zn_0.88S photocatalyst, with average rate of hydrogen production 3.52 mmol/h, which was ca. 1.5 times higher than the Cd_0.1Zn_0.9S photocatalyst. In addition to the high activity, the Cd_0.1Sn_0.01Zn_0.88S also showed high stability at long irradiation time. The role of Sn in preventing electron-hole recombination and photocorrosion was proposed.     

Evaluating microbial safety of slow partial-cooking processes for bacon: use of a predictive tool based on small-scale isothermal meat inoculation studies

The objective of this study was to develop a predictive tool for evaluating the safety of slow cooking of pork products and identifying associated critical limits. Small-scale (25 g) ground pork isothermal inoculation studies were done to determine Salmonella serovars, Escherichia coli O157:H7, and Staphylococcus aureus estimated critical times (time until growth reached a predefined increase of concern). Estimated critical time values ranged from 720 min at 21 degrees C (S. aureus) to 120 min at 40.6 degrees C (E. coli O157:H7) and were used to develop a multiple-temperature-interval predictive tool for non-isothermal processes. To test predictions, cured-pumped pork bellies were inoculated with Salmonella serovars, E. coli O157:H7, and S. aureus, subjected to slow partial cooking, and quantitatively analyzed for pathogens. Processes lasted 6 to 18 h, with the product interior temperature within the 21 to 46 degrees C range for 263 to 1080 min (high-humidity processes) and 217 to 921 min (low-humidity processes). Growth of Salmonella serovars (>0.3 log), E. coli O157:H7 (>0.3 log), and S. aureus (>1.3 log) in the pork belly interior was predicted for 10, 14, and 5 of 18 trials, respectively. The tool was fail-safe, because pathogen growth, relative to time zero, did not occur anytime regardless of whether it was predicted. For the pork belly surface, the tool performed similarly. Estimated critical time values obtained by fitting the Baranyi equation to isothermal experiment data were also determined and, if used in the predictive tool, would result in even more conservative predictions. Our study substantiates the safety of the tested bacon slow partial-cooking processes and the potential usefulness of our isothermal-based tool in process safety evaluation.     

Effects of species interactions on the survival and respiration of Limnodrilus hoffmeisteri and Tubifex tubifex (Oligochaeta, tubificidae) exposed to various pollutants and environmental factors

Laboratory tests were conducted to determine short-term (96 h LC 50) and physiological (respiration) effects of various pollutants (Cd, Hg, NaPCP) and environmental factors (temperature, pH, salinity, anoxia) on mixtures of two freshwater oligochaete species: Limnodrilus hoffmeisteri and Tubifex tubifex. Comparisons with similar data for individual species indicated that mixed species were significantly more tolerant of toxicants, similarly tolerant of environmental factors and less tolerant of anoxia. Although individually these species regulated respiration rate, in mixed culture they were non-regulators and respiratory changes in response to stress appeared to vary depending on test conditions.     

Multireference binary phase-only filter optimized by regions of support

A new formulation of a multiplex filter for filtering-based optical processors, based on the VanderLugt architecture, is presented. The multireference binary phase-only filter (MBPOF), optimized by regions of support (ROS), constitutes a formal rewriting of some multiplex or composite filters including optimization functions, such as the distribution function and the selection function. The first function optimizes the multiplexing of references into the multireference filter. The second function defines the ROS of an object's Fourier spectrum and can be independently used to optimize the conventional binary phase-only filter. Both functions result from a segmentation of the Fourier plane. The MBPOF with ROS can be optically implemented in a filtering-based optical processor owing to a binary-phase spatial light modulator. Simulation and optical results are given for different examples of the BPOF and the MBPOF, both with ROS optimizing different criteria of performance, such as peak-to-correlation energy, discrimination capability, and distortion sensitivity.     

Blade geometry effects on initial dispersion of chopped glass fibers

The effects of blade geometry on the initial dispersion of chopped glass fiber bundles in polystyrene during batch mixing are investigated. Roller, banbury, cam, and sigma blades are evaluated for dispersive efficiency and differences in mechanism. Processed samples are characterized by image analysis to focus upon the initial stages of dispersion. Sigma blades are found to be the most effective blades for initial chopped glass dispersion, while banbury blades prove the least effective. Analytical treatment based on the average time for a volume to pass through high stress regions does not explain the results; chopped glass fiber dispersion does not depend solely upon passage through narrow-gap, high-stress regions.     

Initial dispersion mechanisms of chopped glass fibers in polystyrene

Understanding the mechanisms contributing to the initial stage of dispersion for individual fibers from chopped glass bundles is important for optimizing process conditions and obtaining fiber composites with optimal properties. These studies have shown that under model flow conditions, bundles have two separation modes, rupture and erosion. Both of these occur in a stochastic manner and are dependent upon the internal structure of the bundles. Under chaotic flow, both strain rate and total strain to which the material is exposed are important, though the effect of increasing strain rate decreases at higher total strains. To Obtain consistent minimal dispersion in model flows, the maximum nominal stresses required are higher than 10⁴ Pa for simple shear and 10⁶ Pa for squeezing flows. In contrast, stress levels around 10⁴ Pa yield good dispersion under chaotic flow, implying the flow field is a more significant factor than the stresses imposed.     

Evaluation of congestion control protocols for ABR traffic over ATM networks

Congestion control is very important for effective and stable operation of ATM (Asynchronous Transfer Mode) networks. Owing to the bursty and unpredictable characteristic of data network traffic, its congestion control is particularly a challenge for network researchers and designers. The ATM Forum has recently adopted rate‐based congestion control for ABR (Available Bit‐Rate) traffic which is the service class defined for data network applications. However, there is a number of congestion control schemes prevalent. ATM Forum has decided not to specify switch behaviour for ABR traffic; this has further introduced additional ambiguity. Consequently, an evaluation and comparison of the existing protocols would provide valuable guidance for network designers and engineers; it would also give insight for researchers to explore the essence of different congestion control schemes. In the first part of this paper, we investigate the effectiveness of ABR congestion control in the presence of bursty source traffic and the relationship between the burst time scale and the ABR control time scale. Two ABR congestion control schemes, the ABR Explicit Forward Congestion Indication (EFCI) and ABR Congestion Indication (CI) schemes, are compared with Unspecified Bit Rate (UBR) transport which makes no effort to control congestion. Traffic sources of various burst lengths of 100, 1000, 10000, and an equal mix of 100 and 10000 ATM cells are used in simulations. It is found that ABR congestion control schemes effectively control low frequency, medium to long‐term traffic load transients. This is further supported by the result of integrating TCP over ATM congestion control schemes included in the paper. ABR control schemes do not control high frequency, short‐term load transients well, but ABR control is not necessary in such cases since short‐term transients do not require a large amount of buffering. In the second part of this paper, we evaluate and compare six rate‐based congestion control protocols including Scheme I: EFCI, Scheme II: EFCI with separate RM queues, Scheme III: CI, Scheme IV: CI with separate RM queues, Scheme V: the CAPC2 ER (Explicit Rate), and Scheme VI: the EFCI with utilization‐based congestion indication. Each scheme is simulated and compared in the LAN, WAN, and GFC (General Fairness Configuration) environments specified by the ATM Forum. Effects of varying VC (Virtual Circuits) number and changing endsystem–switch distance has been investigated. Their fairness is also compared using the GFC configuration. We have found that ER control scheme performs significantly better than the other five binary control schemes by its faster response to congestion, smoother regulation of bit‐rates, lower queueing delay, shorter buffer queue length, and fairness. Among the other five schemes, the CI scheme performs better than the EFCI scheme. Providing separate RM queues has significantly improved the EFCI scheme in the WAN environment, but has little effect on the CI scheme. Link utilization‐based congestion detection has suffered from either low utilization or an excess cell loss which is unacceptable in most data applications. Copyright © 2000 John Wiley & Sons, Ltd.     

Predicting pathogen growth during short-term temperature abuse of raw pork, beef, and poultry products: use of an isothermal-based predictive tool

A computer-based tool (available at: www.wisc.edu/foodsafety/meatresearch) was developed for predicting pathogen growth in raw pork, beef, and poultry meat. The tool, THERM (temperature history evaluation for raw meats), predicts the growth of pathogens in pork and beef (Escherichia coli O157:H7, Salmonella serovars, and Staphylococcus aureus) and on poultry (Salmonella serovars and S. aureus) during short-term temperature abuse. The model was developed as follows: 25-g samples of raw ground pork, beef, and turkey were inoculated with a five-strain cocktail of the target pathogen(s) and held at isothermal temperatures from 10 to 43.3 degrees C. Log CFU per sample data were obtained for each pathogen and used to determine lag-phase duration (LPD) and growth rate (GR) by DMFit software. The LPD and GR were used to develop the THERM predictive tool, into which chronological time and temperature data for raw meat processing and storage are entered. The THERM tool then predicts a delta log CFU value for the desired pathogen-product combination. The accuracy of THERM was tested in 20 different inoculation experiments that involved multiple products (coarse-ground beef, skinless chicken breast meat, turkey scapula meat, and ground turkey) and temperature-abuse scenarios. With the time-temperature data from each experiment, THERM accurately predicted the pathogen growth and no growth (with growth defined as delta log CFU > 0.3) in 67, 85, and 95% of the experiments with E. coli 0157:H7, Salmonella serovars, and S. aureus, respectively, and yielded fail-safe predictions in the remaining experiments. We conclude that THERM is a useful tool for qualitatively predicting pathogen behavior (growth and no growth) in raw meats. Potential applications include evaluating process deviations and critical limits under the HACCP (hazard analysis critical control point) system.     

Lay theory of race affects and moderates Asian Americans' responses toward American culture.

People may hold different understandings of race that might affect how they respond to the culture of groups deemed to be racially distinct. The present research tests how this process is moderated by the minority individual's lay theory of race. An essentialist lay theory of race (i.e., that race reflects deep-seated, inalterable essence and is indicative of traits and ability) would orient racial minorities to rigidly adhere to their ethnic culture, whereas a social constructionist lay theory of race (i.e., that race is socially constructed, malleable, and arbitrary) would orient racial minorities to identify and cognitively assimilate toward the majority culture. To test these predictions, the authors conducted 4 studies with Asian American participants. The first 2 studies examine the effect of one's lay theory of race on perceived racial differences and identification with American culture. The last 2 studies tested the moderating effect of lay theory of race on identification and assimilation toward the majority American culture after this culture had been primed. The results generally supported the prediction that the social constructionist theory was associated with more perceived similarity between Asians and Americans and more consistent identification and assimilation toward American culture, compared with the essentialist theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyper-reoriented walking in minimal space

Virtual Reality - We present a new reorientation technique, “hyper-reoriented walking,” which greatly reduces the amount of physical space required in virtual reality (VR) applications...