Effect of additives on the melt rheology and thermal degradation of poly[(R)‐3‐hydroxybutyric acid]

Thermal degradation of poly[(R)−3‐hydroxybutyric acid] (PHB) during melt mixing results in random chain scission that produces shorter polymer chains containing crotonic and carboxyl end groups. One way of preventing this serious reduction of molar mass is to add agents that react with at least two of the newly generated end groups. Different types of commercially available additives known to react with carboxyl group, namely bis(3,4‐epoxycyclohexylmethyl) adipate (BECMA), 2,2'‐bis(2‐oxazoline) (BOX), trimethylolpropane tris(2‐methyl‐1‐aziridinepropionate) (PETAP), triphenyl phosphate (TPP), tris(nonylphenyl) phosphate (TNPP), polycarbodiimide (PCDI), and poly(methyl metharylate‐co‐glycidyl methacrylate) (GMA.MMA) were mixed with PHB by cocasting from solution in chloroform. Dynamic rheology as well as measurements of molar masses before and after dynamic analysis was used to evaluate the effect of the additives on the melt stability of PHB. Measurements of the dynamic shear modulus and the molar mass of molten PHB with the additives PCDI and GMA.MMA showed a minor improvement on the thermal stability. Furthermore, TPP and TNPP did not affect the thermal stability of PHB, whereas the presence of BECMA, BOX, and PETAP gave a strong decrease of the dynamic modulus compared with neat PHB. © 2014 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41836.     

Crack tip stress intensity factors for a crack emanating from a sharp notch

Accurate calibrations are provided for the crack tip stress intensity factor for a crack of finite length emanating from the symmetric tip of a sharp notch, of arbitrary angle, in terms of the generalised stress intensity quantifying remote loading of the notch. The solution is applied to example problems and shown to be accurate for cases where the crack is much shorter then the notch depth.     

Closure at the root of a sharp notch

Sharp notches subject to remote axial compression suffer closure of the root. In this paper we address this, and determine a first-order approximation to the extent of closure based on the asymptotic solution for a semi-infinite notch. This is then applied to an edge notch, and it is shown that the extent of closure is very small indeed, and likely to be smaller by several orders of magnitude than the notch root radius in any practically realisable case. It also follows that the notch root plasticity present for real materials is likely to encompass this region, and that the ‘open’ notch solution may be used without loss of accuracy.     

Application limits and data correction in number of molecules and brightness analysis

Number of molecules and Brightness (N&B) has been proposed for measuring the molecular brightness and number of fluorophores in time‐sequence of images, in live cells. If the fluorescently tagged‐proteins are mobile in the illumination volume, the stoichiometry of their oligomers can be derived from the increase of the brightness of the fluorescent dyes due to clustering. We examine aspects concerning extra‐fluctuation effects induced by cell shifts and photobleaching, which yield large overestimates of the clusters size and sub‐unit counts. We develop an offline corrective approach consisting in frame re‐alignment and boxcar filtering for recovering precision of the analysis. Using simulations we derive general criteria for approaching this analysis, and assess the application limits of the corrective procedure. We tested the approach in extreme experimental conditions (few pixels, large extra‐variance perturbations), in which we analyzed the minimal increases of brightness as that expected between a monomeric and dimeric GPI‐mEGFP constructs. We show how most of the perturbing effects can be abolished, and obtain the correct the brightness of GPI‐mEGFP monomers and dimers. Microsc. Res. Tech. 76:1135–1146, 2013. © 2013 Wiley Periodicals, Inc.     

A correlation of the process zone properties in complete, incomplete and almost complete fretting contacts

A careful analytical comparison is made of the size and shape of the process zones present in a range of fretting fatigue experiments. These include the conventional Hertzian contact, the ‘flat and rounded’ pad problem and the classical square-ended pad geometries. The results clearly display the load and geometry regimes where the ‘flat and rounded’ pad performance may be matched with either of the limiting forms. This should permit a unifying re-interpretation of fatigue data already obtained from each of the three sources.     

Identification of an epitope of alpha-enolase (a candidate plasminogen receptor) by phage display

Alpha-enolase is an ubiquitous cytoplasmic glycolytic enzyme which also exhibits cell surface mediated functions and a structural role in the lens of some species. An alpha-enolase related molecule (alpha-ERM) is present on the surfaces of neutrophils, monocytes and monocytoid cells and has the capacity to specifically bind plasminogen, suggesting that alpha-ERM may function as a plasminogen receptor. We have generated a monoclonal antibody (mAB), 9C12, against alpha-ERM. This mAB reacted with both alpha-ERM and purified human alpha-enolase in Western blotting and in enzyme linked immunosorbent assays (ELISA). mAB 9C12 detected a cell surface associated molecule on human peripheral blood neutrophils and on U937 human monocytoid cells as assessed by fluorescence activated cell sorting (FACS) analyses. In addition, mAB 9C12 recognized an intracellular pool of alpha-enolase/alpha-ERM in permeabilized U937 cells. A phage display approach was employed to identify the alpha-enolase epitope recognized by mAB 9C12. Random fragments of 100-300 base pairs (bp), obtained from the full length human alpha-enolase cDNA, were cloned into the filamentous phage vector pComb3B, to generate a phage-displayed peptide library. Recombinant phages binding to mAB 9C12 were selected and their DNA inserts characterized by direct sequencing. All of the fragments which bound to mAB 9C12 encoded the common sequence DLDFKSPDDPSRYISP, spanning amino acids 257-272 of human alpha-enolase. This sequence is located within an external loop of the molecule. These data indicate that this sequence contains the epitope recognized by mAB 9C12 and is, therefore, exposed on the cell surface, further suggesting that alpha-enolase and alpha-ERM share common amino acid sequences.     

Photocatalysts prepared from layered clays and titanium hydrate for degradation of organic pollutants in water

Reaction between titanium hydrate sol of strong acidity and four smectite clays were utilized to create composite nanostructures of titanium dioxide (TiO₂) and silicate nanoparticles. The acidic sol solution reacts with the clay platelets and leaches out part of the magnesium or aluminum in the clay, while the sol particles hydrolyze further, yielding larger precursors of TiO₂ nanoparticles and condense on the fragmentised pieces of the leached silicate. Moreover, introducing PEO surfactants into the synthesis can significantly increase the porosity and surface area of the composite solids. The TiO₂ in the product are crystal grains of several nanometres in size. They disperse on silicate plates or are separated by silicate fragments and voids such that they are accessible to organic molecules. The mechanism of the synthesis reaction is distinguishingly different from conventional pillaring process. The composite solids provide highly effective photocatalysts for the degradation of phenol and synthetic dyes in aqueous solution.     

The impact of supply chain disruption on the closed-loop supply chain configuration profit: a study of sourcing policies

A closed-loop supply chain configuration (CLSCC) encompasses the decisions related to the optimal selection of options at each stage of a closed-loop supply chain (CLSC) for the introduction and reconstruction of new products. The extant literature ignores the impact of supply chain disruptions on CLSCC. An attempt is made to fill this gap in this study. Thus, an integrated multi-sourcing CLSCC optimisation model for new and reconstructed products is developed. The optimisation model presented is a mixed-integer nonlinear programming (MINLP) model. Based on a real-world case study of an auto-parts manufacturer in India presented, a comprehensive set of computational experiments, scenario analyses are conducted. The key finding/observation that resulted from our computational experiments is that multi-sourcing generates higher net present value of total profit compared to single sourcing under the risk of supply chain disruption. Several other observations and managerial insights are drawn from computational experiments, and scenario analyses. Firms interested in configuring their CLSC under the risk of supply chain disruption may use the study's outcomes to understand the profit impact of various CLSCC parameters, individually and in combination.     

Women's struggle for urban safety. the Canadian experience and its applicability to the Israeli context

This article examines the ways in which issues of women's safety in public space are integrated into planning practice and policy. It deals with two processes of struggle for urban safety, addressing the integration of ‘voices from the field’ into urban administration and planning, and questioning the possible adaptation of experiences of such integration, as developed in one socio‐culture system, into another. The article focuses on a number of Canadian cities, and assesses if their experience is applicable to cities in Israel. Thus it considers the transferability of knowledge and the potential of cross‐culture study, in relation to the production of professional knowledge. The first part of the article introduces the main issues to be explored in the article and considers these in the context of recent theoretical, professional and public debates, especially as related to gender and urban safety, and in relation to concepts of power, knowledge, meaning and identity. The second part presents the major findings of a research project related to local Canadian actions for urban safety and the urban policies adopted for its provision. The third part analyzes the applicability of the Canadian experience to the Israeli context and contains preliminary conclusions and recommendations as to the transferability of this experience.