Antinucleating action of polystyrene on the isothermal cold crystallization of poly(ethylene terephthalate)

The effect of polystyrene (PS) on the kinetics of the cold crystallization of poly(ethylene terephthalate) (PET) was thoroughly investigated. The PET/PS blends were essentially immiscible, as observed by dynamic mechanical thermal analysis, which showed two distinct glass‐transition temperatures, and by scanning electron microscopy. The neat PET and its blends were isothermally cold‐crystallized at various temperatures, and the kinetic parameters were determined with the Avrami approach. PET and its blends presented values of the Avrami exponent close to 2, and the kinetic constant increased with the crystallization temperature increasing. For all the crystallization temperatures studied, the presence of only 1 wt % PS significantly reduced the rate of cold crystallization of PET. A further increase in the PS concentration did not show any significant influence. The blends presented higher values of the activation energy for cold crystallization, which was estimated from Arrhenius plots. The equilibrium melting temperature of neat PET was determined on the basis of the linear Hoffman–Weeks extrapolative method to be ～ 255°C. This value decreased in the presence of PS, and this suggested limited solubility between PET and PS. From the spherulitic growth equation proposed by Hoffman and Lauritzen, the nucleation parameter was obtained, and it was shown to be higher for the neat PET than for the blends. Moreover, a transition of regimes (I → II) was observed in both PET and its blends. From the investigations conducted here, it is clear that PS in small amounts causes a reduction in the rate of PET crystallization, acting as an antinucleating agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Computerized smoking cessation program for the worksite: Treatment outcome and feasibility.

This study demonstrated the effectiveness of a computer-delivered smoking cessation program for the worksite. 58 VA Medical Center employees were randomly assigned to a computer group (computerized nicotine fading and stop-smoking contest) or a contest-only group. In comparison with the contest-only group, the computer group had nonsignificantly higher abstinence rates across follow-up, had marginally lower CO levels at the 3- and 6-month follow-ups, and smoked cigarettes with lower nicotine levels at the 10-day and 6-month follow-ups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Degradation kinetics of epoxidized soybean oil composites filled with sisal fiber

Epoxidized soybean oil (ESO) composites were cured with methyl tetrahydrophthalic anhydride (MTHPA) and 2,4,6-tris(dimethylaminomethyl)phenol (DEH 35) as a catalyst, sisal fibers were added at 10% and 30% of percent per weight. Composites curing was monitored using Fourier transform infrared spectroscopy, whereas the thermal stability and the degradation kinetics were investigated using thermogravimetry (TG). ESO/MTHPA/DEH35/S10 and ESO/MTHPA/DEH35/S30 composites displayed curing temperatures approximately 100°C lower related to ESO/MTHPA/DEH35, as well as higher degree of conversion. Sisal addition improved the thermal stability, shifting the weight loss shifting the weight loss onset to higher temperature (from 82 to 120°C). Thermal degradation energy $$ was determined using Friedman, Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models. Sisal significantly increased $$, especially in the intermediate phase (α = 0.2 and 0.8). The degradation kinetics was investigated by TG, and the degradation mechanisms modeled using Kamal-Sourour, Sestack-Berggren, and 1st order (F1), showed excellent fit, with R² > 0.99. Acquired results demonstrate that sisal fiber addition benefited the curing process and increased the thermal stability of ESO composites.     

Bacterial Community of Koumiss from Mongolia Investigated by Culture and Culture-Independent Methods

The bacterial community of fermented horse milk (koumiss) from Mongolia was studied using three methods: cultivation, direct identification by 16S rRNA clone library and denaturing gradient gel electrophoresis (DGGE). Ninety-eight strains were isolated by traditional cultivation and 61 of those were randomly selected for further identification by 16S rRNA gene sequencing. The strains were dominated by lactic acid bacteria (LAB; six different lactobacilli), Acinetobacter, Bacillus and Psychrobacter. Construction of the clone library analysis revealed that 16S sequences of 220 clones, genus Lactobacillus was dominant, but Streptococcus thermophilus, Acetobacter pasteurianus and uncultured clones were also detected. Ten unique bands were sequenced from the DGGE and revealed: Lactococcus lactis, Lactococcus lactis subsp. lactis, Clostridium acidurici, Acinetobacter johnsonii, Dickeya sp., Enterobacter sp., Pseudomonas sp., Raoultella sp., and Ruminococcus sp.. In vitro growth inhibition of three human pathogens, Escherichia coli, Enterobacter sakazakii and Staphylococcus aureus by 14 culturable bacteria displayed that only three of the isolates tested inhibit growth of E. sakazakii while most of the other bacteria delayed growth of the target bacteria.     

Measuring Relevance in Support of Design Reuse from Archives of Building Product Models

This paper investigates the use of text analysis techniques to measure relevance between objects in product models. This relevance measure is used to support design reuse from an archive of product models from previous projects. We consider several techniques from the field of information retrieval for comparing documents. Next, we explore whether we can improve the performance of the relevance measure by considering contextual building model elements. The paper concludes with an evaluation and discussion of the techniques considered. We conclude that relatively good retrieval results can be achieved with short texts and sparse building models such as those that occur in current industry practice.     

Sensitivity of 0.1 mu m MOSFETs to manufacturing fluctuations

A sensitivity analysis of 0.1 mu m MOSFETs to manufacturing fluctuations has been carried out. The analysis reveals that the electrical parameter sensitivity in deep submicrometre devices differs from the currently produced micrometre size devices, making a revision of the validity of conventional semiconductor manufacturing heuristics for future technology mandatory.<>     

Briefe Emmy Noethers and P.S. Alexandroff

There are only five letters and two postcards which were written by Emmy Noether to P.S. Alexandroff that have been preserved. These will be edited in this paper. More than any other source, these letters and postcards give an insight into Emmy Noether's privacy, and her sympathy for the problems of her pen pal and colleagues. They illuminate her judgement of different colleagues, students, «mathematical grandchildren» and their papers. They also inform about relationships within the mathematicians' community and the working atmosphere in Goettingen and the US after 1933.

The author thanks Prof. Dr. Walter Purkert, Bonn, for the reference to the writings of Emmy Noether, and Prof. Dr. Albert Shiryaev, Moscow, for the kind publication permission.

     

Peirce algebras

We present a two-sorted algebra, called aPeirce algebra, of relations and sets interacting with each other. In a Peirce algebra, sets can combine with each other as in a Boolean algebra, relations can combine with each other as in a relation algebra, and in addition we have both a set-forming operator on relations (the Peirce product of Boolean modules) and a relation-forming operator on sets (a cylindrification operation). Two applications of Peirce algebras are given. The first points out that Peirce algebras provide a natural algebraic framework for modelling certain programming constructs. The second shows that the so-calledterminological logics arising in knowledge representation have evolved a semantics best described as a calculus of relations interacting with sets.     

Proline versus charge concept for protein stabilization against proteolytic attack

The virtue of the so-called ‘proline concept’ andthe ‘charge concept’ for stabilizing protease-susceptibleregions of a protein structure was compared on bovine pancreaticribonuclease A. Alanine 20 and serine 21, both of whichare located in a loop that is susceptible to the unspecificproteases subtilisin Carlsberg, subtilisin BPN', proteinaseK and elastase, were replaced with proline or lysine by site-directedmutagenesis. The rate constant of proteolysis was decreasedby up to three orders of magnitude for the proline mutants dependingon the site of the mutation and the protease used. In contrast,substitution by lysine increased the proteolytic resistanceby only one order of magnitude characterizing the ‘prolineconcept’ as superior to the ‘charge concept’.Although the four applied proteases are considered to be unspecific,the degree of stabilization of the ribonuclease molecule variedconsiderably, indicating the impact of individual differencesin their substrate specificity on the proteolytic resistanceand degradation pathway of the target protein. Received May 12, 2003; revised October 23, 2003; accepted October 30, 2003