Microstructure and mechanical properties of a polyethylene/polydimethylsiloxane composite prepared using supercritical carbon dioxide

A polymer composite of polyethylene (PE) and polydimethylsiloxane (PDMS) was prepared using supercritical carbon dioxide despite the two polymers usually being immiscible and possessing a phase‐separated morphology. This article reports in detail the preparation, microstructure, crystallinity, and mechanical properties of the resulting PE/PDMS composite. The formation mechanism of the PE/PDMS composite consisted of supercritical impregnation of an octamethylcyclotetrasiloxane (D4) monomer and an initiator into a PE substrate followed by in situ polymerization within the substrate. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and small‐angle X‐ray scattering measurements showed that PE and PDMS were blended at the nanometer level. The PDMS generated in the amorphous region of PE did not affect its crystallinity. Dynamic viscoelastic analyses and tensile tests were used to measure the mechanical properties of the composites including storage and Young's modulus, fracture stress, and strain. These properties were found to depend on the composition of the composite. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Freezing heat transfer along a horizontal cooled plate with a separated region

Experiments were carried out to determine the effect of flow separation on freezing heat transfer characteristics along a horizontal cooled flat plate immersed within a rectangular duct. The flow separation was induced by a vertically situated thin plate placed against the flow at the leading edge of a uniformly cooled plate. The degree of flow separation was altered by employing vertical plates of various heights. The Reynolds number and the cooling temperature ratio ranged from 5.6 x 10² to 8.4 x 10⁴ and from 3.0 to 10.0, respectively. The measurements showed that the flow separation exerts a marked influence on the local ice formation characteristics. Two kinds of ice formation of convex and concave profiles were observed to occur as a function of the Reynolds number, as well as of the cooling temperature ratio. © 1998 Scripta Technica. Heat Trans Jpn Res, 27(1): 43–56, 1998     

An Engineered Old Yellow Enzyme that Enables Efficient Synthesis of (4R,6R)‐Actinol in a One‐Pot Reduction System

(4R,6R)‐Actinol can be stereo‐selectively synthesized from ketoisophorone by a two‐step conversion using a mixture of two enzymes: Candida macedoniensis old yellow enzyme (CmOYE) and Corynebacterium aquaticum (6R)‐levodione reductase. However, (4S)‐phorenol, an intermediate, accumulates because of the limited substrate range of CmOYE. To address this issue, we solved crystal structures of CmOYE in the presence and absence of a substrate analogue p‐HBA, and introduced point mutations into the substrate‐recognition loop. The most effective mutant (P295G) showed two‐ and 12‐fold higher catalytic activities toward ketoisophorone and (4S)‐phorenol, respectively, than the wild‐type, and improved the yield of the two‐step conversion from 67.2 to 90.1 %. Our results demonstrate that the substrate range of an enzyme can be changed by introducing mutation(s) into a substrate‐recognition loop. This method can be applied to the development of other favorable OYEs with different substrate preferences.     

Boron‐Based Inhibitors of Acyl Protein Thioesterases 1 and 2

Ras proteins are of importance in cell proliferation, and hence their mutated forms play causative roles in many kinds of cancer in different tissues. Inhibition of the Ras‐depalmitoylating enzyme acyl protein thioesterases APT1 and ‐2 is a new approach to modulating the Ras cycle. Here we present boronic and borinic acid derivatives as a new class of potent and nontoxic APT inhibitors. These compounds were detected by extensive library screening using chemical arrays and turned out to inhibit human APT1 and ‐2 in a competitive mode. Furthermore, one of the molecules was demonstrated to inhibit Erk1/2 phosphorylation significantly.     

Plasma organochlorine levels and subsequent risk of breast cancer among Japanese women: a nested case-control study

To our knowledge, no prospective study has examined the association between blood levels of organochlorines and breast cancer risk in Asian countries. Here, we tested the hypothesis that higher blood levels of organochlorines are associated with an increased risk of breast cancer in Japanese women. A total of 24,226 women subjects of the Japan Public Health Center-based Prospective Study aged 40 to 69 years who responded to the baseline questionnaire and provided blood in 1990-1995 were followed to December 2002. During 10.7 years follow-up, 144 cases of breast cancer were newly diagnosed. Two matched-controls for each case were selected from the cohort. Plasma levels of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), and beta-hexachlorocyclohexane (beta-HCH) were measured. A conditional logistic regression was used to estimate the odds ratio (OR) of breast cancer according to cholesterol-adjusted organochlorine levels based on 139 matched pairs. We found no statistically significant positive association between plasma organochlorine level and breast cancer risk. Adjusted ORs for p,p'-DDT, HCB, and beta-HCH were less than 1. For p,p'-DDE, adjusted OR for the highest versus lowest quartile was 1.48 (95% confidence interval 0.70-3.13; p for trend=0.25). A stratified analysis by menopausal status showed positive associations for p,p'-DDT and p,p'-DDE in premenopausal but not postmenopausal women, although without statistical significance. Our data do not support the hypothesis that plasma levels of p,p'-DDT, p,p'-DDE, HCB, and beta-HCH are associated with an overall increased risk of breast cancer among Japanese women.     

Preferences for and attitudes towards street flowers and trees in Sapporo, Japan

The benefits of street vegetation, in particular the importance of trees, for urban dwellers have been given wide attention. There is, however, a lack of research on flowers as an element of street vegetation. This paper explores preferences for various street-planting models, particularly those with different compositions of flowers, with or without trees. Eighty-one residents of Sapporo evaluated 59 photomontage simulations and answered a questionnaire concerning their attitudes to street flowers. Results revealed trees to be the factor with the greatest influence on preference. Among possible elements for the space beneath trees from a choice including soil, grass, hedge and flowers, flowers were the most favoured. In particular, low and ordered compositions of brightly coloured flowers were the most preferred. Tall flowers were not found to be either attractive or appropriate for streetscapes in this case study. A factor analysis of the variables related to attitudes towards street flowers revealed the following five factors: “psychological benefits and aesthetic value”, “natural–environmental”, “practical concerns”, “effort to maintain” and “non-aesthetic”. The highest rated items were all related to the aesthetic and psychological benefits of street flowers. Flowers were the most preferred element beneath street trees and were seen as not only contributing to the aesthetic quality of a street but as also having a positive influence on psychological well-being.     

A quantitative evaluation of the production performance of ice slurry by the oscillatory moving cooled wall method

Ice slurry has recently been utilized for a variety of engineering fields such as thermal energy storage and high-density energy transportation. In this paper, as a production method of ice slurry, the oscillatory rotating cooled tube method was proposed. A vertical cooled tube was installed in a test vessel that was filled with ethylene glycol solution being forced to move within an aqueous binary solution to produce the ice slurry. Production performance of ice slurry by the present method was determined under a variety of conditions, such as initial concentration of solution, angular acceleration and rotation angle for the oscillation motion of the cooled tube. The production performance was evaluated analytically by constructing a numerical model. The analysis was made to determine the separation condition of ice layer from the cooled tube surface at first, then the production rate of ice slurry was assessed. It was found from the present study that the ice slurry was produced continuously under the appropriate operating conditions in which the separation of ice layer was caused by oscillating motion of the cooled tube.     

Test data generation for web application using a UML class diagram with OCL constraints

In this paper, we report on our current work toward efficient and effective verification of web application’s basic design. We use a UML class diagram with Object Constraint Language (OCL) to describe the application behaviors and data constraints. Then we generate test data from the formally represented specifications. We make the observation that key web application behaviors can be captured through table size constraints as well as data constraints like foreign key constraints. Based on the observation, we translate the OCL specification into the equivalent constraints using table size expressions. We present a scheme to generate test data from the translated constraints using a Satisfiability Modulo Theories solver. We employ two techniques to reduce constraints. The first is string handling and the other is decomposition of table structures. We also report on an experimental result of test data generation. The result indicates a potential that our scheme works well for real applications in reasonable times.