Purification and characterization of an endopeptidase from Lactobacillus delbrueckii subsp. bulgaricus B14

An intracellular endopeptidase was purified from cell-free extracts of Lactobacillus delbrueckii subsp. bulgaricus B14 by anion exchange chromatography on DEAE-Sepharose, hydroxyapatite chromatography, second anion exchange chromatography on Mono-Q, and metal-chelating affinity chromatography. The endopeptidase was a monomer with a molecular mass of approximately 70 kDa determined by SDS-PAGE and gel filtration. Various oligopeptides (e.g. Met-enkephalin, bradykinin) were hydrolysed by the endopeptidase. Exopeptidase activity and cleavage of dipeptides or tripeptides was not observed. The K_M value for the cleavage of Metenkephalin was 1.2 mM. Temperature and pH optima were 47 °C and pH 7.7, respectively. The endopeptidase was inhibited by the classical agents for metal-dependent (EDTA) and serine (DFP) enzymes. Activity was increased by Co²⁺ and Mg²⁺, no effect was observed with Ca²⁺. After inhibition with EDTA, enzyme activity could be restored fully by Co²⁺. Activity was inhibited by Zn²⁺, Mn²⁺, Fe²⁺, Cu²⁺, Cd²⁺ and Hg²⁺. The N-terminal sequence of the endopeptidase was determined as: H₂N-Val-Arg-Gly-Gly-Ser-Gly-Asp-Thr-Thr-Val-0H.     

Abrasion phenomena in twill tencel fabric

The abrasion characteristics of Tencel fabrics were evaluated by Martindale abrasion and laundering, and the breakdown mechanism of fibers was surveyed by scanning electron microscopy. The fabric was subjected to pad‐dry‐cure treatment with two different types of modified dimethyloldihydroxyethylene urea resins (Reaktant DH and Reaktant FC). Although the degree of dry abrasion varied with different resins, the damage exhibited by individual fibers differed little from untreated to resin‐treated; the major mechanism of abrasion was through friction, and the mechanism of fiber failure was multiple splitting and transverse cracking. In untreated Tencel, the characteristic feature of wet abrasion was massive fibrillation, and in crosslinked fabrics, the wet abrasion mechanism was through fiber slippage and slicing action, although in the Reaktant FC‐treated fabric, the wet abrasion mechanism was more through slicing than through fiber splitting. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1391–1398, 2006     

Automating manual reward systems

The introduction of Personal Computers has enabled Industrial Engineers to automate many aspects of their responsibilities, thus becoming significantly more productive. One aspect which clearly benefits from automation is the creation, implementation, and periodic maintenance of Pay-for-Performance Reward Systems. However, selecting the correct software package is not easy. Industrial Engineers currently have a variety of fully automated software packages to choose from which can range from $2,000 – $100,000. The initial cost alone may make it difficult to Justify for a small plant. Furthermore, if you have a variety of reward systems (Gainsharing - Small Group - One for One) finding a single program to handle all of them may be impossible.

This was a problem Norton Company faced five years ago. We are a fortune 500 company with manufacturing plants located throughout the world, using a variety of reward systems. To remain cost competitive in all aspects of our business, we had to find a way to reduce the on-going maintenance costs of our incentive systems.

Investigating alternatives uncovered a low cost, flexible solution to our problem. The use of off-the-shelf spreadsheet and data base software enabled us to fully automate all aspects of our reward systems.     

用功放驱动热电致冷器来调节温度

系统设计师设计光纤通信系统时经常会遇到一个问题，那就是如何确保激光系统可在某一温度范围内保持其特性。若温度改变，激光系统的中心频率也会随着改变。为了确保频率保持稳定，新一代的固态激光模块都内置一个热电致冷器(Thermoelectric Cooler, TEC)，以便将热能泵入模块或将热能释出，以调节温度。热电致冷器按照佩尔蒂埃效应(Peltier effect) 的原理运作。每当直流电流经热电致冷器时，热能便会由热电致冷器的一边传送至另一边，令热电致冷器的一边转“热”，另一边则转“冷”。若直流电被逆转，原先热的一边会转冷，冷的一边则会…     

Three-parameter vs. two-parameter Weibull distribution for pultruded composite material properties

The three-parameter and two-parameter Weibull distributions are compared using 26 mechanical property data sets of fiber-reinforced polymeric (FRP) composite materials manufactured by the pultrusion process. Both strength and stiffness properties were examined. The probability distributions were compared on the basis of goodness of fit, nominal design values, and allowable load to achieve uniform reliability. It is recommended that the two-parameter Weibull distribution be used to characterize FRP composite material properties. The primary basis for this recommendation is small differences in nominal design values and small differences in allowable loads between the two-parameter and three-parameter Weibull distributions. Other supporting reasons for the recommendation are similar observed significance levels in distribution fitting, computational efficiency, and the fact that the location parameter of the three-parameter Weibull distribution is near the first order statistic.     

Correction to Construction of Panoramic Image Mosaics with Global and Local Alignment

International Journal of Computer Vision -     

Performance of a non‐load‐bearing steel stud gypsum board wall assembly: Experiments and modelling

A gypsum wall assembly was exposed to an intense real‐scale compartment fire. For the wall assembly, temperatures were measured at the exposed face, within the stud cavity, and at the unexposed face during the fire exposure. Total heat flux gauges were used to measure the temporal variation of the energy incident on the walls, and cameras, both visual and infrared, were used to image the unexposed face of the wall assembly during the fire exposure. The behaviour of the wall assembly under the fire load is discussed as are current model results for a simulation of the fire test. Copyright © 2006 John Wiley & Sons, Ltd.