Hollow Fiber Ultrafiltration of Maple Sap: A Performance Study

In an attempt to develop new products from maple sap, membrane technology was used to fractionate and concentrate macromolecular components (10,000 daltons or larger). Permeate fluxes increased with transmembrane pressure, reaching a maximum at 190–200 kPa, at 8–10°C. The flux profiles were similar to those of protein solutions and fruit juices. This method of clarification was successfully applied to obtain a clear “cold sterilized” sap. Application of ultrafiltration to maple farms or industries are discussed.     

一种新的补偿硅电阻率/掺杂浓度模型(英文)

硅片或硅块的电阻率与掺杂浓度的关系模型不适用于补偿硅,如精纯冶金级硅(UMG-Si)。目前尚无合适的理论模型可以准确解释补偿硅实验和观测结果间存在的差异。基于电解液理论提出一种包含电离平衡常数的新方法,可以得到单掺杂硅的电荷载子迁移率Thurber曲线。当掺杂硅中包含一种以上掺杂物质时,需要采用数值算法来解决多重平衡系统。研究表明这类系统表现出一种缓冲溶液的特定行为。通过计算化合物的热力学参数获得平衡常数,并利用现有的电化学知识(Nerust方程和Butler-Volmer方程)提出一个普遍理论。因为硅/掺杂物系统构成一个弱电解质固溶体,电解质溶液理论为太阳能电池行为的认知提供了一个很好的物理模型和数学框架。     

Treating mineral metabolism disorders in patients undergoing long hemodialysis: A search for an optimal strategy

In hemodialysis (HD) patients, mineral metabolism (MM) disorders have been associated with an increased mortality rate. We report the evolution of MM parameters in a stable HD population undergoing long hemodialysis by performing an annual cross-sectional analysis for every year from 1994 to 2008. The therapeutic strategy has changed: the dialysate calcium concentration has decreased from a mean of 1.7 ± 0.1 to 1.5 ± 0.07 mmol/L and has been adapted to parathyroid hormone serum levels (from 1 to 1.75 mmol/L). The use of calcium-based and aluminum-based phosphate binders has decreased and they have been replaced by sevelamer; alfacalcidol has partly been replaced by native vitamin D. The percentage of patients with a parathyroid hormone serum level between 150 and 300 pg/mL has increased from 9% to 67% (P<0.001); the percentage of patients with phosphataemia between 1.15 and 1.78 mmol/L has increased from 39% to 84% (P<0.001). The percentage of those with albumin-corrected calcemia between 2.1 and 2.37 mmol/L has increased from 29% to 61% (P<0.001), and that of patients with a calcium-phosphorous product (Ca × P) level >4.4 mmol/L decreased from 8.8% to 2% (P=0.02). Although patients undergo long and intensive HD treatment, MM disorders are common. However, an appropriate strategy, mostly consisting of native vitamin D supplementation, progressive replacement of calcium-based phosphate binders with non–calcium-based ones, and individualization of dialysis session duration and dialysate calcium concentration, would result in a drastic improvement.     

PREDICTION OF SOLIDS CIRCULATION RATE IN THE RISER OF AN INTERNALLY CIRCULATING FLUIDIZED BED (ICFB)

A predictive mathematical model based on pressure drop in the riser of an Internally Circulating Fluidized Bed (ICFB) is developed to predict solids circulation rate (Gs). The values of G_s predicted using the model agree well with the experimental data. The model also predicts well G_s at higher operating temperatures in the riser of an ICFB.     

Characterization of Culturable PAH and BTEX Degrading Bacteria from Heavy Oil of the Rancho La Brea Tarpits

Novel petroleum degrading bacteria have been identified in heavy oil from natural asphalt seeps using DNA-based methods, but there is little knowledge of the extent to which these bacteria can be cultured by selective enrichments on different aromatic hydrocarbons. Here we report the species composition of bacterial communities from a 40,000 yr-old asphalt deposit that could be grown on selected petroleum compounds. Species compositions of the degrader communities determined by PCR-DGGE and 16S rDNA sequencing showed that selective enrichment using (PAHs) and BTEX (benzene, toluene, ethyl benzene, and xylene) as growth substrates produced relatively simple degrader communities, and included a predominant species, Pseudomonas stutzeri, which grew on multiple compounds. PCR-based techniques further identified genes encoding naphthalene dioxygenase and catechol 2,3-dioxygenase from P. stutzeri in the enrichment cultures. The results suggest that only a small portion of the asphalt-inhabiting community can be cultured under aerobic conditions on individual substrates. Within these communities were several new species that merit further characterization as consortia, as well as new isolates of the cosmopolitan degrader, P. stutzeri.     

Chemical composition and microbial evaluation of Argentinean Corrientes cheese

The chemical and microbial composition of an artisanal cheese made from raw cow's milk produced and consumed in the province of Corrientes (north-eastern Argentina) was evaluated using standard methods. Corrientes cheese has high moisture content (50–60%), normal protein and fat contents (21–27 and 22–26% respectively), and is low in salt (0.5–2.0% w/w). Microbial counts also varied significantly between samples (colony-forming units per gram ranges covering logs of 5–11), probably due to environmental contamination in the raw material. These results will help produce higher quality Corrientes cheeses with well-defined characteristics.     

Use of the quantum entropy of non-probabilistic matrices in automatic control

The quantum mechanical entropy of density matrices defined by Von Neumann in quantum physics has been generalized in the form of quantum entropy of non-probabilistic matrices, and it is shown that the latter can be of some use in automatic control. This quantum entropy can be thought of as a measure of structure complexity and its application is quite relevant and meaningful in the following topics: stability of linear and non-linear systems, robustness and order reduction. Quantum entropy appears to be a new weighted combination of eigenvalues which would allow us to re-examine some problems with new points of view relating to information theory without probability.