Interfacial tension of polypropylene/polystyrene: Degradation of polypropylene

The coefficient of the decrease of the interfacial tension of polypropylene/polystyrene with temperature is considerably higher than the value of other polymer pairs. This coefficient can be estimated by considering the change of the interaction parameters with temperature, but this approach fails for polypropylene/polystyrene, and other mechanisms are expected to play a role. In this paper it is shown that polypropylene starts to degrade at higher temperatures, leading to smaller polymer chains, which decrease the interfacial tension. Besides the change of the interaction parameters with temperature, these smaller molecules also contribute to the temperature coefficient, leading to an apparently high coefficient. The smaller molecules, however, lead to a permanent lower interfacial tension, e.g. the interfacial tension of polypropylene/polystyrene at 200°C is 4.9, 3.9, and 3.0 mN/m, if the polypropylene is first processed at 200, 250, and 300°C, respectively.     

Causal attributions predict rate of immune decline in HIV-seropositive gay men.

Research has suggested that attributions—the perceived causes of events—may affect psychological and physical health and the immune system. The authors hypothesized that attributions reflecting negative beliefs about the self, the future, and control would affect helper T cell (CD4) decline and onset of AIDS in individuals with HIV, either directly or through associations with psychological states such as depression. HIV+ gay men (N?=?86) participated in a structured interview from which causal attributions were extracted and coded. Attributing negative events to aspects of the self significantly predicted faster CD4 decline over 18 months following the interview, controlling for potential psychological, behavioral, social, and health mediators such as depression and health behavior. However, attributions did not predict AIDS diagnosis during the study period. The results support the idea that causal attributions related to beliefs about the self may have an influence on the immune system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confocal imaging with bilateral scanning and array detectors

A novel arrangement for confocal microscopy is presented, in which the key elements are the use of an array detector such as a CCD for confocal image collection and the use of one double-sided scanning mirror element for bilaterally scanning the object and collecting the data on the CCD. The resulting arrangement is shown to be capable of confocal imaging with high photon efficiency under adjustable conditions of confocality and varying image acquisition rates, i.e. from slow speed up to real-time imaging. Either laser or conventional light sources may be utilized. In addition to CCD registration, direct observation by eye of the confocal image in fluorescence is also possible.     

On Reciprocating Elastomeric Seals: Calculation of Film Thicknesses Using the Inverse Hydrodynamic Lubrication Theory

The elastohydrodynamic lubrication (EHL) problem of an axi-symmetric, elastomeric, reciprocating seal may be considered as one of a heavily loaded line contact with only small piezo-viscous effects. A method is presented to calculate the overall film thickness for the stationary, isothermal situation with sufficient lubricant supply and negligible surface roughness effects. It applies the inverse theory to the frictionless dry contact pressure distribution, considering the influence of the boosting action in the entry zone of the film. Its validity is shown for the isoviscous EHL of the Hertzian contact. The finite element method (FEM) may be used to calculate the contact situation of mounted and pressurized seals. Important aspects of such calculations are discussed. To calculate film thicknesses using such FEM results, a computer program PROGRES was written. Good correspondence between the predictions of PROGRES and experimental outstroke film thicknesses are obtained for a rectangular rod seal with rounded edges.     

A new kinetic model for titanium dioxide mediated heterogeneous photocatalytic degradation of trichloroethylene in gas-phase

This paper focuses on the kinetics of photocatalytic removal and carbon mineralization of gaseous trichloroethylene (TCE) on near-UV irradiated TiO₂ Degussa P25. Experiments were carried out in a flat-plate photoreactor at TCE inlet concentrations of 100–500 ppmv, relative humidities (RH) of 0–62% and gas residence times of 2.5–60.3 s. Gas residence time distribution (RTD) curves revealed an axial dispersed plug flow in the photoreactor with Peclet numbers above 59.4. For all experimental conditions, the carbon mineralization efficiency (5.1–73.0%) was lower than the removal efficiency (8.6–99.9%) and dichloroacetylchloride (DCAC) was detected as a gas-phase degradation product. TCE removal efficiencies increased with lower TCE inlet concentrations, lower RH and higher gas residence times. Evaluating different kinetic models by least squares analysis, it was shown that the Langmuir–Hinshelwood (LH) model could not give an adequate fitting to the experimental results. A new kinetic model, explicitly taking into account electron–hole pair reactions, was developed based on linear TCE adsorption–desorption equilibrium and first order reaction kinetics. The new kinetic model described the experimental results in a more accurate way, as exemplified by a more randomly distributed set of residuals and by a reduction of the sum of squares (SSQ) by a factor 1.7–8.5. The effect of TCE gas-phase concentration, RH and light intensity on adsorption–desorption kinetics, electron–hole concentrations and chemical conversion rates is discussed.     

Apolipoprotein E Gene Variability and Cognitive Functions at Age 79: A Follow-Up of the Scottish Mental Survey of 1932.

Apolipoprotein E (APOE) genotype is a possible influence on nonpathological cognitive aging. The authors studied 462 community-dwelling, 79-year-old people born in 1921, whose childhood IQ had been assessed in the Scottish Mental Survey of 1932 (Scottish Council for Research in Education, 1933). Adjusting for sex, childhood IQ, and self-reported illnesses, the authors found that those with an APOE e4 allele had significantly lower Wechsler Logical Memory (D. Wechsler, 1987) scores than those without an e4 allele. Those people with APOE s2/e3 genotypes had significantly higher Wechsler Logical Memory scores than e3/s3, who were significantly higher than e3/e4. Neither nonverbal reasoning nor verbal fluency were affected. In this sample, APOE genotype contributed to verbal memory in old age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prone position favors motor development of infants

OBJECTIVE: To determine the motor development in infants sleeping in the supine position compared to infants sleeping in the prone position, and to compare the levels of motor development of infants playing only in the supine position and of infants playing in the prone position as well. DESIGN: Prospective blinded comparing study. SETTING: Department of Physical Therapy, Maasziekenhuis, Boxmeer, the Netherlands. METHODS: Various measuring instruments were used in the home environment to determine the levels of motor development at the age of 5 months of 21 healthy infants born at term selected from a group of 160 infants attending the infant welfare clinic. RESULTS: Infants sleeping in the prone position (n = 8) showed a higher motor development than infants sleeping in the supine position (n = 13). Infants playing in the prone and supine position (n = 5) had a higher motor development than infants who played exclusively in the supine position (n = 15). CONCLUSION: Sleeping and playing in the prone position was accompanied by a higher motor development in healthy mature-born infants at the age of 5 months.     

Role of TNF‐α polymorphism ‐308 in neurosensory irritation

Neurosensory cutaneous discomfort in response to topical products is common, yet the relationship between symptoms such as stinging and visible irritation is currently unclear. The presence of a polymorphism at position ‐308 on the TNF‐α gene has been associated with skin irritation, i.e., erythema, dryness. Individuals with a G to A transition (AA/GA genotypes) have a lower threshold to experimentally induced irritation than those with the wild type (G allele, GG genotype). We investigated the effect of this polymorphism on neurosensory irritation (NSI). DNA genotyping was used to determine the allele type amongst a population of health care workers. The neurosensory response to lactic acid and water on the nasolabial folds and hands was assessed using a quantitative lactic acid sting test. Both genotypes had a more intense response to lactic acid compared with water on the face. The AA/GA genotypes had directionally higher scores from lactic acid (P = 0.1) and significantly higher stinging intensities from water (P = 0.001) on the face. For the hands, stinging intensities were higher for lactic acid and water amongst the AA/GA genotypes (P = 0.03 and 0.006 respectively). NSI to lactic acid was significantly higher on the face than on the hands (P < 0.05). Our findings indicate that subjects with the A transition at position ‐308 on the TNF‐α gene experience more intense NSI with common ingredients, i.e., lactic acid and water, than those with the wild type. TNF‐α polymorphism ‐308 may account for some of the inter‐individual variability in response to skin care practices.     

Abstracts: Natural moisturizing factors in the stratum corneum I. Effects of lipid extraction and soaking

pp. 13–22 Natural moisturizing factor (NMF) is essential for appropriate stratum corneum hydration, barrier homeostasis, desquamation, and plasticity. It is formed from filaggrin proteolysis to small, hygroscopic molecules including amino acids. We hypothesized that common lipid extraction and soaking in water would alter the level of NMF in the upper stratum corneum (SC) and its biophysical properties. A novel method of measuring and quantifying the amino acid components of NMF is presented. Adhesive tapes were used to collect samples of the SC and were extracted with 6 mM perchloric acid for analysis by reverse‐phase high‐performance liquid chromatography (HPLC).The HPLC results were standardized to the amount of protein removed by the tapes. An increase in NMF was found with increased SC depth. Also, the combination of extraction and soaking was found to increase NMF loss relative to control or to extraction or soaking alone. Our results indicate that common skin care practices significantly influence the water binding materials in the upper SC. The findings have implications for the evaluation and formulation of skin care products.