Acylated ascorbate stimulates collagen synthesis in cultured human foreskin fibroblasts at lower doses than does ascorbic acid

Acylated derivatives of ascorbic acid were found to be active in a number of biochemical and physiological processes. In the present study we investigated the effects of 6-O-palmitoyl ascorbate on collagen synthesis by cultured foreskin human fibroblasts. Our observations indicate a marked stimulatory effect on collagen synthesis by 6-O-palmitoyl ascorbate in the concentration range of 5-20 microM, while the synthesis stimulated by ascorbic acid was maximal at concentrations of 20-100 microM. Cells treated with 10 microM palmitoyl ascorbate for 36 h exhibited a production of collagen threefold greater than those in the presence of 10 microM ascorbic acid, and it was about the same as in cells treated with 100 microM ascorbic acid. By 48 h differences were not significant. Acylated ascorbate impaired vitality of the treated fibroblasts at concentrations exceeding 20 microM in media supplemented with 0.5% FCS. However, most of the cytotoxic effect was neutralized by FCS at a concentration of 10%. The resistance of acylated ascorbate against oxidative degradation as well as the role of free radicals in the modulation of collagen synthesis by ascorbic acid and by its derivatives is discussed.     

Prospects for application of post-consumer used plastics in food packaging

The two most widely used polymers in packaging in recent years are polyethylene terephthalate (PET) and polyethylene (PE). The biggest fractions of these polymers are not re-utilized, in spite of the fact that they possess excellent properties even after their first application. The ban on using recycled polymers in food packaging applications and the lack of good value outlets for these materials causes them to end up in landfills. The high cost nylon, used in packaging primarily as high gas barrier laminates with PE, also finds its way to landfills. In this case, the reason is the difficulty of recycling different polymers that are incompatible. Thus, the Municipal Solid Waste (MSW) stream transferred to landfills contains many plastic packages. These packages are being blamed as a major pollutant of the environment in spite of the fact that all plastics contribute only a small percentage to the weight of the garbage in landfills. If proper and cost effective applications for the recycled polymers could be developed, the waste related to their disposal could be limited. In addition, the contribution of plastic packages to the environmental problem could be diminished. In the present paper, the possibility of sandwiching a contaminated PET layer between two layers of the virgin material was studied. The aim of the study was to determine whether such an operation could lower the migration level of contaminants from a multilayer structure (containing a recycled layer of PET) to values below the limits required by regulatory agencies. The diffusion coefficients (required to determine migration) of four organic liquids in PET were determined. As a result of the sandwiching operation, the amount of pollutant (toluene) migrating into the food simulant was reduced by two orders of magnitude. The properties of PE/nylon blends were also studied. It was found that the high gas barrier properties of nylon are preserved in the blend when proper processing conditions are used. Therefore, the recycled material could be used as a centre layer in a multilayer structure providing good gas barrier properties to this structure.     

人性化的用户界面

在过去，移动电话只是带内置地址簿的固定电话的无线替代品。向拥有更多连接性、更多数据和更多性能、更精巧设备的加速推进，使广大用户产生了更多、更强烈的市场需求。移动电话的生态系统正努力寻求适当的途径实现数据和服务，并充分友好地为用户所使用。只有语音功能的移动电话市场将会越来越小。     

Effects of computerized mediation of analogical thinking in kindergartens

Abstract  The current study describes an attempt to improve children's analogical thinking through the use of a 'humanized' computer program. This program was experimentally designed to incorporate several basic features of what has been defined theoretically and empirically as basic criteria of human mediation to children. The objective of the study was to examine the possibility of improving the educational benefits of using computers in early childhood education. More specifically, it was hypothesized that by introducing into a computer program basic features of human mediation, it would be possible to raise children's educational gains to the level of the gain achieved when they work with an adult mediator. Subjects were 120 Israeli-born kindergarten children between 4.5 and 6 years old. Despite no differences in test scores between the two experimental groups a higher frequency of 'stopping to think' (in contrast to trial and error responses) was found in the experimental group working with an adult as compared to the experimental group working independently.     

Structure-property relationships in blends of linear low- and conventional low-density polyethylene as blown films

Three-layer coextruded blown (either blend or composite) films, made of low-density polyethylene and linear lowdensity polyethylene (1:1 ratio) of identical density, were compared. The tensile properties of both systems are nearly as high as those of the linear polyethylene while high strain rate properties including impact strength and tear resistance of the composite film are superior. Some structural insight was obtained by thermal analysis and thermoelastic measurements. Structure property relationships are discussed in light of the unique behavior, structure, and morphology of linear low-density polyethylene. The two polyethylenes are only compatible to a rather limited extent mainly affecting their blend behavior. However, a strong mutual reinforcement effect was observed.     

Simultaneous intraparticle forced convection,diffusion and reaction in a porous catalyst—II: Selectivity of sequential reactions

The selectivity of a sequence of isothermal irreversible heterogeneous reactions

within a catalytic pellet is investigated under conditions where intraparticle forced convection is a non-negligible transport mechanism. The nature of the effect of the internal filter flow depends mostly on the value of the Thiele modulus, φ₂, of the desired (middle) species. The asymptotic values of the selectivity, as φ₂ → 0 and φ₂ → ∞, are unaltered, independent of the strength of the internal flow. The intermediate region is divided into two parts. In the subregion with lower values of φ₂ the selectivity is enhanced. In the other subregion, with higher values of φ₂, the selectivity is significantly retarded to values which can be markedly below the lower asymptote. These trends are common to both poor and good selective catalysts.     

Annular flow of two immiscible liquids I. Mechanisms

A study was made of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal-pipe inlet in initial concentric flow. Extent of the annular flow, its break-up mechanisms and the subsequent flow patterns encountered were investigated with the aid of high-speed photography. Annular-flow break-up was found to occur by one of two mechanisms: collapse of the core-liquid by varicose Rayleigh-type waves or rupture of the top-wall liquid-film, attenuated by the ascent of the lighter core-liquid. Flow patterns observed after break-up involve fine dispersions, slugs or stratified layers. Charts mapping flow-pattern zones show conditions under which annular-flow holds over a considerable extent.     

Mid-infrared fiber-optic attenuated total reflection spectroscopy of the solid-liquid phase transition of water

Measurements of mid-infrared (MIR) absorption spectra of water and heavy water were carried out by fiber-optic evanescent wave spectroscopy, using silver halide (AgClBr) infrared fibers. Such measurements were performed for the first time on one sample, during the solid-liquid phase transition. From the variation of the spectra with temperature we found a new isosbestic point (at 3280 cm(-1) for H(2)O or at 2475 cm(-1) for D(2)O) and we identified five components of the O-H (O-D) stretch band. These phenomena have provided new information about the molecular structure of water.     

On Interpretation of ESCA Spectra with Application to Thymine and Other Molecules

1s binding energies are calculated for nitrogen atoms in thymine, pyrrole, adenine, and pyridine and for carbon atoms in thymine, adenine, pyrrole, and furan, and compared with experimental values. Calculations are performed in the framework of a perturbational model using CNDO molecular wave functions. Interactions of the 1s electron with its own atom are calculated exactly whereas interactions with neighbor atoms are calculated according to two levels of approximation: (1) Point charge approximation. (2) Rigorous calculations of integrals. Magnitudes of the different interactions and integrals are analysed. The questions of assignments of ESCA shifts and the errors inherent in the calculations are discussed.     

Enhanced inactivation of E. coli bacteria using immobilized porous TiO2 photoelectrocatalysis

Immobilized TiO₂ nanotube electrodes with high surface areas were grown via electrochemical anodization in aqueous solution containing fluoride ions for photocatalysis applications. The photoelectrochemical properties of the grown immobilized TiO₂ film were studied by potentiodynamic measurements (linear sweep voltammetry), in addition to the calculation of the photocurrent response. The nanotube electrode properties were compared to mesoporous TiO₂ electrodes grown by anodization in sulfuric acid at high potentials (above the microsparking potential) and to 1 g/l P-25 TiO₂ powder. Photocatalyst films were evaluated by high resolution SEM and XRD for surface and crystallographic characterization. Finally, photoelectrocatalytic application of TiO₂ was studied via inactivation of E. coli. The use of the high surface area TiO₂ nanotubes resulted in a high photocurrent and an extremely rapid E. coli inactivation rate of ∼10⁶ CFU/ml bacteria within 10 min. The immobilized nanotube system is proven to be the most potent electrode for water purification.