In vitro degradation of dermal sheep collagen cross-linked using a water-soluble carbodiimide

Bacterial collagenase was used to study the susceptibility of dermal sheep collagen (DSC) cross-linked with a mixture of the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide hydrochloride and N-hydroxysuccinimide (E/N-DSC) towards enzymatic degradation. Contrary to non-cross-linked DSC (N-DSC), which had a rate of weight-loss of 18.1% per hour upon degradation, no weight loss was observed for E/N-DSC during a 24 h degradation period. The tensile strength of the E/N-DSC samples decreased during this time period, resulting in partially degraded samples having 80% of the initial tensile strength remaining. The susceptibility of E/N-DSC samples towards enzymatic degradation could be controlled by varying the degree of cross-linking of the samples. Ethylene oxide sterilization of E/N-DSC samples made the material more resistant against degradation compared with non-sterilized E/N-DSC samples. This may be explained by a decrease of the adsorption of bacterial collagenase onto the collagen owing to reaction of ethylene oxide with remaining free amine groups in the collagen matrix.     

High performance liquid chromatographic separation of sucrose fatty acid esters

The synthesis of sucrose fatty acid esters always results in complex mixtures. Two procedures for quantitative analysis of sucrose monoesters, respectively sucrose diesters, by means of high performance liquid chromatography on reversed-phase columns, are described. A mixture of methanol and water (85:15, v/v) was used for the separation of the monoesters, while methanol, ethyl acetate and water (65:25:10, v/v/v) was used for the separation of diesters. These methods gave information about the amount of monoesters and diesters in the product; the ratio between sucrose monopalmitate and sucrose monostearate, and the number of the most important structure isomers. A complete separation of all the possible diester products seemed to be impossible, due to the presence of more complex structure isomers. The described procedures can give important support during preparative work on sucrose fatty acid esters and also in the evaluation of these products for application purposes.     

From enterprise architecture to business models and back

In this study, we argue that important IT change processes affecting an organization’s enterprise architecture are also mirrored by a change in the organization’s business model. An analysis of the business model may establish whether the architecture change has value for the business. Therefore, in order to facilitate such analyses, we propose an approach to relate enterprise models specified in ArchiMate to business models, modeled using Osterwalder’s Business Model Canvas. Our approach is accompanied by a method that supports business model-driven migration from a baseline architecture to a target architecture and is demonstrated by means of a case study.     

Whiteness and fluorescence of fabrics

A method was devised for measuring the whiteness of fabrics containing optical brighteners. It is simple in operation and gives excellent agreement with the visual appraisal by 27 observers of the whiteness for fabrics with different values for their fluorescence, lightness, yellowness or blueness, and redness or greenness. The fabrics contained different quantities of various blues and optical brighteners. Apart from duplicates it requires only four measurements for each surface, viz., lightness, tristimulus amber and blue reflectance, and the tristimulus blue part of the fluorescent light. Yellowness or blueness, redness or greenness, fluorescence effect on the whiteness, whiteness without fluorescence, and whiteness including fluorescence are calculated from the measurements. The method also indicates which fabrics cannot be called “near white” because they are too gray or too strongly colored. It can be adapted to different compositions of the incident light with regard to the relative intensity of the ultraviolet and visible portions.     

Induction=I-Axiomatization+First-Order Consistency

In the early 1980s, there was a number of papers on what should be called proofs by consistency. They describe how to perform inductive proofs, without using an explicit induction scheme, in the context of equational specifications and ground-convergent rewrite systems. The method was explicitly stated as a first-order consistency proof in the case of pure equational, constructor-based specifications. In this paper, we show how, in general, inductive proofs can be reduced to first-order consistency and hence be performed by a first-order theorem prover. Moreover, we extend previous methods, allowing nonequational specifications (even non-Horn specifications) and designing some specific strategies. Finally, we also show how to drop the ground convergence requirement (which is called Saturatedness for general clauses).     

Optimization of microfluidic particle sorters based on dielectrophoresis

In this paper, improved dielectrophoretic particle sorters are introduced for application in microfluidics. The optimal shape of the electrodes is briefly discussed and two new sorter topologies are introduced. Based on the theoretical considerations, four sorter configurations are analyzed in detail. The devices are modeled by calculating the particle trajectories from a combination of finite-element simulations and analytical calculations. The four sorter configurations have been realized in chips based on silicon, glass, and SU8 technology. The simulations and the experimental results are in very good agreement and confirm that with the new sorter configurations, much higher performance can be realized (+200%) compared to the classical line electrodes found in literature.     

The Role of the Locus Coeruleus in Mediating the Attentional Blink: A Neurocomputational Theory.

The attentional blink refers to the transient impairment in perceiving the 2nd of 2 targets presented in close temporal proximity. In this article, the authors propose a neurobiological mechanism for this effect. The authors extend a recently developed computational model of the potentiating influence of the locus coeruleus-norepinephrine system on information processing and hypothesize that a refractoriness in the function of this system may account for the attentional blink. The model accurately simulates the time course of the attentional blink, including Lag 1 sparing. The theory also offers an account of the close relationship of the attentional blink to the electrophysiological P3 component. The authors report results from two behavioral experiments that support a critical prediction of their theory regarding the time course of Lag 1 sparing. Finally, the relationship between the authors' neurocomputational theory and existing cognitive theories of the attentional blink is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pervaporation of water-n-propanol mixtures through membranes composed of poly(N-vinylpyrrolidone)-poly(methacrylic acid) complexes

Membranes composed of poly(vinylpyrrolidone)-poly(methacrylic acid) (PVP-PMAA) complexes appear to be suitable for pervaporation of water-n-propanol mixtures. The membranes are selective to water. The separation factor α increases with increasing content of propanol, w_PrOH, and reaches a maximum value for w_PrOH at about 0.8 in the case of PVP-rich membranes, and close to w_PrOH = 1 for PMAA-rich membranes. All membranes exhibited maximum swelling at w_PrOH of ca. 0.4. At constant w_PrOH of 0.8 the value of α changes in a complicated manner with the composition of the membrane. Under this condition of constant w_PrOH, α runs parallel with the swelling degree. A tentative explanation is proposed for results pertaining to membranes containing not too high excesses of PVP or PMAA.