Home  About us  Contact
 

Of Chemicals (of + chemical)

Distribution by Scientific Domains
Chemistry60%

Kinds of Of Chemicals

  • variety of chemical
    		•

    Selected Abstracts

    Single-Molecule Spectroscopy for Plastic Electronics: Materials Analysis from the Bottom-Up

    ADVANCED MATERIALS, Issue 15 2010
    John M. Lupton
    Abstract , -conjugated polymers find a range of applications in electronic devices. These materials are generally highly disordered in terms of chain length and chain conformation, besides being influenced by a variety of chemical and physical defects. Although this characteristic can be of benefit in certain device applications, disorder severely complicates materials analysis. Accurate analytical techniques are, however, crucial to optimising synthetic procedures and assessing overall material purity. Fortunately, single-molecule spectroscopic techniques have emerged as an unlikely but uniquely powerful approach to unraveling intrinsic material properties from the bottom up. Building on the success of such techniques in the life sciences, single-molecule spectroscopy is finding increasing applicability in materials science, effectively enabling the dissection of the bulk down to the level of the individual molecular constituent. This article reviews recent progress in single molecule spectroscopy of conjugated polymers as used in organic electronics. [source]

    Teen workers' exposures to occupational hazards and use of personal protective equipment

    AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 10 2008
    Carol W. Runyan MPH
    Abstract Background Prior research indicates that working adolescents seek care for the toxic effects of on-the-job chemical and environmental hazard exposures. Methods This cross-sectional survey of a nationally representative sample of 866 adolescent workers in the retail and service sector examines their exposures, personal protective equipment (PPE) use, and training. Results Two-thirds of respondents were exposed to continuous, very loud noise, 55% to thermal hazards and 54% to chemical hazards. Few teens reported using any PPE, though those who had been trained reported somewhat higher usage. Conclusions Teens working in the retail and service sectors experience a variety of chemical, thermal, biologic and noise exposures. Efforts to eradicate such exposures need to be complemented by increased provision of PPE and appropriate training in their use by employers. Am. J. Ind. Med. 51:735,740, 2008. Published 2008 Wiley-Liss, Inc. [source]

    Underarm cosmetics and breast cancer

    JOURNAL OF APPLIED TOXICOLOGY, Issue 2 2003
    P. D. Darbre
    Abstract Although risk factors are known to include the loss of function of the susceptibility genes BRCA1/BRCA2 and lifetime exposure to oestrogen, the main causative agents in breast cancer remain unaccounted for. It has been suggested recently that underarm cosmetics might be a cause of breast cancer, because these cosmetics contain a variety of chemicals that are applied frequently to an area directly adjacent to the breast. The strongest supporting evidence comes from unexplained clinical observations showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast, just the local area to which these cosmetics are applied. A biological basis for breast carcinogenesis could result from the ability of the various constituent chemicals to bind to DNA and to promote growth of the damaged cells. Multidisciplinary research is now needed to study the effect of long-term use of the constituent chemicals of underarm cosmetics, because if there proves to be any link between these cosmetics and breast cancer then there might be options for the prevention of breast cancer. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Induced changes in total serum IgE concentration in the Brown Norway rat: potential for identification of chemical respiratory allergens

    JOURNAL OF APPLIED TOXICOLOGY, Issue 1 2002
    E. V. Warbrick
    Abstract A variety of chemicals can cause sensitization of the respiratory tract and occupational asthma that may be associated with IgE antibody production. Topical exposure to chemical respiratory allergens such as trimellitic anhydride (TMA) has been shown previously to induce increases in the total serum concentration of IgE in BALB/c strain mice. Contact allergens such as 2,4-dinitrochlorobenzene (DNCB), which apparently lack respiratory sensitizing potential, fail to provoke similar changes. However, it became apparent with time that there was some inter-animal variation in constitutive and inducible IgE levels. We have now examined the influence of topical exposure to TMA and DNCB on serum IgE levels in the Brown Norway (BN) rat. Such animals can be bled serially and thus it is possible to perform longitudinal analyses of changes in serum IgE concentration. The kinetics of IgE responses therefore can be followed on an individual animal basis, allowing discrimination between transient and sustained increases in serum IgE concentration. Rats (n = 5) were exposed on shaved flanks to 50% TMA, to 1% DNCB (concentrations that elicit comparable immune activation with respect to draining lymph node cellularity and proliferation) or to vehicle alone. Total IgE was measured by enzyme-linked immunosorbent assay in serum samples taken prior to and 14,42 days following initial exposure. Those animals having high pre-existing IgE levels (>1.0 µg ml,1) were excluded from subsequent analyses. The levels of serum IgE in the majority of rats exposed to DNCB or vehicle alone remained relatively stable throughout the duration of all the experiments conducted, although some animals displayed transient increases in serum IgE. Only TMA treatment was associated with a significant and sustained increase in the level of serum IgE in the majority of experiments. The elevated concentrations of IgE induced by topical exposure to TMA are persistent, the results reported here demonstrating that induced changes in IgE are maximal or near maximal at approximately 35 days, with a significant increase in IgE demonstrable for at least 42 days following the initiation of exposure. Interestingly, although TMA and DNCB at the test concentrations used were found to be of comparable overall immunogenicity with regard to lymph node activation and the induction of lymph node cell proliferation, there were apparent differences in humoral immune responses. Thus, not only did exposure to TMA stimulate increases in total serum IgE concentration and the production of specific IgE antibody, but also a more vigorous IgG antibody response was provoked by TMA compared with DNCB. These data suggest that the measurement of induced changes in serum IgE concentration in the BN strain of rat is able to differentiate between different classes of chemical allergen. Given the inter-animal variation in IgE production, it would be prudent to incorporate a concurrent assessment of responses induced by treatment with TMA as a positive control against which to assess the activity of other test materials. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Autothermal Catalytic Partial Oxidation of Glycerol to Syngas and to Non-Equilibrium Products

    CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 1 2009
    David
    Abstract Glycerol, a commodity by-product of the biodiesel industry, has value as a fuel feedstock and chemical intermediate. It is also a simple prototype of sugars and carbohydrates. Through catalytic partial oxidation (CPOx), glycerol can be converted into syngas without the addition of process heat. We explored the CPOx of glycerol using a nebulizer to mix droplets with air at room temperature for reactive flash volatilization. Introducing this mixture over a noble-metal catalyst oxidizes the glycerol at temperatures over 600,°C in 30,90,ms. Rhodium catalysts produce equilibrium selectivity to syngas, while platinum catalysts produce mainly autothermal non-equilibrium products. The addition of water to the glycerol increases the selectivity to H2 by the water gas shift reaction and reduces non-equilibrium products. However, water also quenches the reaction, resulting in a maximum in H2 production at a steam/carbon ratio of 2:3 over a Rh-Ce catalyst. Glycerol without water produces a variety of chemicals over Pt, including methylglyoxal, hydroxyacetone, acetone, acrolein, acetaldehyde, and olefins. [source]