Maltose hydrolysis kinetics with glucoamylase immobilized in porous glass fibers in a tubular flow reactor

Glucoamylase has been covalently immobilized in controlled pore glass fibers packed parallel to the axis of a tubular reactor. Flow kinetic studies have been carried out for a range of flow rates and substrate concentrations at 50°C and pH 4.5. Diffusion control has been found negligible with high flow rates and substrate concentrations. The apparent Michaelis constant was three orders of magnitude higher than that of the free enzyme. As flow rate and substrate concentration decrease, the extent of diffusion control increased up to a moderate degree. The immobilized glucoamylase was more stable than the free enzyme when incubated at 50°C.     

Comprehension-monitoring failure in skilled adult readers.

Examined whether monitoring failure or an illusion of knowing occurs when a reader's self-assessment of comprehension is high but an objective measure indicates comprehension failure. Unadulterated expository text was used. 48 undergraduates read either a difficult or an easy expository passage under instructions intended to elicit either deep processing or relatively shallow (but still semantic) processing. The illusion of knowing occurred primarily when the reading level of the passage was difficult and the instructions cued a relatively shallow level of processing. Ss who exhibited an illusion of knowing tended to have shown distortions in their passage summaries, whereas Ss who knew that they had failed to comprehend were more likely to have omitted information relevant to the main point. Findings provide a documentation of metacomprehension failure without the use of the contradiction paradigm. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance evaluation of fault-branch detection in TDM passive optical networks by spectral analysis of interferometric signals

A new fault-branch detection scheme is proposed to troubleshoot the breaks of any distribution fibers in a time-division multiplexing (TDM) passive optical network. We employ a continuous optical frequency sweeper at the optical line terminal (OLT) and an interferometric (IF) device at each optical network unit (ONU). By analyzing the spectrum of the returned combined signals at the OLT, we can obtain the status of all branches. This detection method not only uses a small optical frequency band for surveillance monitoring, but is also simple to operate. Furthermore, a modified architecture is proposed to relax the specifications of IF devices. The tolerance of the IF device length was analyzed using the Monte–Carlo simulation method.     

Random effects mixture models for clustering electrical load series

For purposes such as rate setting and long‐term capacity planning, electrical utility companies are interested in dividing their customers into homogeneous groups or clusters in terms of the customers’ electricity demand profiles. Such demand profiles are typically represented by load series, long time series of daily or even hourly rates of energy consumption of individual customers. The high dimension and time series nature inherent in the load series render existing methods of clustering analysis ineffective. To handle the high dimension and to take advantage of the time‐series nature of load series, we introduce a class of mixture models for time series, the random effects mixture models, which are particularly useful for clustering the load series. The random effects mixture models are based on a hierarchical model for individual components. They employ highly flexible antedependence models to effectively capture the time‐series characteristics of the covariance of the load series. We present details on the construction of such mixture models and discuss a special Expectation‐maximization (EM) algorithm for their computation. We also apply these models to cluster the data set which had motivated this research, a set of 923 load series from BC Hydro, a crown utility company in British Columbia, Canada.     

Optimization of the sputtering process parameters of GZO films using the Grey–Taguchi method

This paper examines the optimization of the process parameters of GZO films deposited on polyethylene terephthalate substrates by R.F. magnetron sputtering using the Taguchi method, aiming to obtain highly transparent and conductive films. The influences of the various sputtering factors (R.F. power, sputtering pressure, deposition time, substrate temperature and post-annealing temperature) on electrical resistivity and structural, morphological and optical transmittance of GZO films are analyzed. The electrical resistivity and the optical transmittance of GZO films were improved by post-annealing the substrate during the deposition process. Experimental results indicate the optimal process parameters in GZO films deposited on polyethylene terephthalate substrates can be determined effectively. The electrical resistivity of GZO films is decreased from 1.194 × 10⁻³ Ω cm to 8.627 × 10⁻⁴ Ω cm and the optical transmittance is increased from 86.148% to 90%, leading to multiple performance characteristics in deposition qualities through the Grey–Taguchi method.     

Two‐phase flow behavior in microtube reactors during biodiesel production from waste cooking oil

Flow patterns in the course of transesterification of waste cooking oil (WCO), sunflower oil (SFO) with water and/or oleic acid as a model of WCO, and pure SFO in the presence of a KOH catalyst in microtubes were investigated. FAME yield for the transesterification of WCO reached more than 89% in the microtube reactors with a residence time of 252 s at 333 K. The flow patterns when using WCO were changed from a liquid–liquid slug flow at the inlet region to a parallel flow at the middle region, and then to a homogeneous liquid flow at the outlet region as the reaction proceeded at 333 K. Fine droplets containing glycerol and methanol generally formed in oil slugs when using pure SFO, but were almost unobservable when using WCO. The soap produced from free fatty acids was considered to be the main factor affecting the flow patterns of WCO and SFO. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Synthesis and Characterization of Organic Dyes Containing Various Donors and Acceptors

New organic dyes comprising carbazole, iminodibenzyl, or phenothiazine moieties, respectively, as the electron donors, and cyanoacetic acid or acrylic acid moieties as the electron acceptors/anchoring groups were synthesized and characterized. The influence of heteroatoms on carbazole, iminodibenzyl and phenothiazine donors, and cyano-substitution on the acid acceptor is evidenced by spectral, electrochemical, photovoltaic experiments, and density functional theory calculations. The phenothiazine dyes show solar-energy-to-electricity conversion efficiency (η) of 3.46–5.53%, whereas carbazole and iminodibenzyl dyes show η of 2.43% and 3.49%, respectively.     

Antimicrobial activity of biodegradable polysaccharide and protein-based films containing active agents

Significant interest has emerged in the introduction of food packaging materials manufactured from biodegradable polymers that have the potential to reduce the environmental impacts associated with conventional packaging materials. Current technologies in active packaging enable effective antimicrobial (AM) packaging films to be prepared from biodegradable materials that have been modified and/or blended with different compatible materials and/or plasticisers. A wide range of AM films prepared from modified biodegradable materials have the potential to be used for packaging of various food products. This review examines biodegradable polymers derived from polysaccharides and protein-based materials for their potential use in packaging systems designed for the protection of food products from microbial contamination. A comprehensive table that systematically analyses and categorizes much of the current literature in this area is included in the review.     

Use of Soy Protein and Microbial Transglutaminase as a Binder in Low-sodium Restructured Meats

ABSTRACT: Pork sticks were prepared by mixing pork chucks with various amounts of bisulfite-treated soy protein and microbial transglutaminase (MTGase) to evaluate the potential of using soy protein as meat binders. According to tensile strength, the favorable conditions for binding the restructured pork chunks were 5% soy protein containing 0.2% NaHSO₃ and 20 unit MTGase/g, and the setting condition was 60 min at 40°C. The tensile strength and cooking yield of restructured pork sticks made with bisulfite-treated soy protein and MTGase were much higher than those of using salt, suggesting the high potential of using soy protein and MTGase as binders in products where NaCl reduction is desired.     

Mineral oil-chitosan emulsion coatings affect quality and shelf-life of coated eggs during refrigerated and room temperature storage

Effects of mineral oil (MO) and 4 emulsions (prepared with different emulsifier types) of MO and chitosan solution (CH) at a fixed ratio of MO:CH = 25:75 as coating materials in preserving the internal quality of eggs were evaluated during 5 wk at 25 °C and 20 wk at 4 °C. Generally, as storage time increased, Haugh unit and yolk index values decreased whereas weight loss increased. However, MO and/or 4 emulsion coatings minimized the weight loss (<1.5%) and preserved the albumen and yolk quality of eggs (with the final B grade) for at least 3 wk longer than those observed for noncoated eggs at 25 °C. At 4 °C, all coated eggs changed from AA to A grade after 5 wk and they maintained this grade for 10 wk (5 wk longer than that of noncoated eggs). Although refrigeration (4 °C) alone could maintain the B grade of noncoated eggs for up to 20 wk, coating treatments were necessary to keep the weight loss below 2%. Compared with 4 °C, the increasing weight loss showed stronger negative correlation (P < 0.01) with the decreasing Haugh unit (-0.46 to -0.89) and yolk index (-0.36 to -0.89) at 25 °C. The emulsifier type used in this study generally did not affect the internal quality of eggs. Salmonella spp. detection was negative for all coated and noncoated eggs. This study demonstrated that MO and MO:CH emulsion coatings preserved the internal quality, prolonged the shelf-life, and minimized weight loss (<2%) of eggs.