Flexible polyurethane foam. II. Fire retardation by tris(1,3-dichloro-2-propyl) phosphate. Part B. Examination of the condensed phase (the pyrolysis zone)

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is used commercially as a fire retardant for flexible polyurethane foams. It was found to act both in the condensed (pyrolysis zone) and the vapor (flame) phases. The extent of its activity in the individual phases depends on the way in which the specimen is ignited. Under conditions of candle-like, top-down burning, retardation seems to occurs mainly in the condensed phase by a mechanism apparently based largely on the barrier properties of a phosphorus-containing carbonaceous layer that builds up on top of the liquid pyrolyzing layer beneath the flame. As the formation of this barrier requires time, extinguishment in this mode is relatively slow. Extinguishment is much faster in bottom-up burning, where the flame appears to be the main site of the retardation. In this mode, because of the orientation of the specimen relative to the flame, a disproportionately large amount of TDCPP enters the flame. It is proposed that TDCPP decomposition products, HCl and other low-fuel-value materials dilute the fuel vapors sufficiently to reduce their flame propagation velocity to below that at which they stream out of the pyrolysis zone. This pushes the flame away from the pyrolysis zone, uncoupling the thermal feedback mechanism that produces the fuel. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:231–254, 1998     

高纯度番茄红素的制备

番茄酱需要经过预处理后才能用于制备高纯度的番茄红素。该文详细考察了预处理各因素对番茄红素提取率和纯度的影响,确定了制备高纯度番茄红素的最优工艺为:取100 g番茄酱,加入200 mLc(Na2CO3)=0.5mol/L的水溶液于40℃皂化30 m in,然后用稀硫酸将皂化液中和起泡至pH=4~5。离心分离,得到的固体部分用100 mLw(C2H5OH)=95%的乙醇处理10 m in后,用有机溶剂进行提取。提取液在低温下结晶,制得的番茄红素质量分数达到了95%,整个过程的提取率为79%。     

Conductive coating films based on low density In2O3 powders and polymer latexes

Several kinds of conductive coating films were prepared from a low-density indium(III) oxide powder (which was employed because it provides a much higher volume for the same weight) and polymer latexes. The low-density In₂O₃, which is an electrically conductive pigment, was prepared by pyrolysis followed by the combustion of water-swellable polymer microspheres imbibed with In(NO₃)₃, the precursor of In₂O₃. Either acrylamide/N,N'-methylenebisacrylamide or poly(vinylalcohol)/glutaricdialdehyde was used to generate spherical hydrogel particles. The polymer latexes with which the In₂O₃ was mixed had a soft core and a hard shell structure to ensure that the coating film has suitable mechanical properties in addition to conductivity. Acrylonitrile/butadiene/styrene copolymer ABS or acrylonitrile/butylacrylate/styrene copolymer ABAS latexes were used as binders for the conductive pigment. The powder coating followed by hot pressing, the water-borne coating consisting of low-density In₂O₃ and polymer latexes followed by curing, or the colloidal dispersion coating was used to deposit flexible conductive coating films on polyester sheets. The conductive pigment density and the polymer latexes' size and flowability are the factors that affect the characteristics of the film. We found that the colloidal suspension coating procedure based on ABAS latexes achieves better electrical and mechanical properties for the coating films. © 1996 John Wiley & Sons, Inc.     

Interaction of proteins with ultrafiltration membranes: Development of a nonfouling index test

Ultrafiltration membranes were prepared from homopolymer [polyacrylonitrile (PAN), polyethersulfone (PES), and polyvivylidenefluoride (PVDF)] and acrylonitrile copolymers with increasing acrylamide content. The membranes containing acrylamide were more hydrophilic and had a smaller dispersive surface energy than those prepared from the acrylonitrile homopolymer. A new nonfouling index (NFI) test was devised and appears to distinguish well between ultrafiltration membranes of different hydrophilicity–hydrophobicity balance. The NFI indices of acrylamide containing copolymer membranes were much higher than those of membranes cast with commercial membrane materials such as PAN, PES, and PVDF. The NFI of ultrafiltration membranes increased as acrylamide substitution in the copolymer increased. The use of acrylamide containing copolymers substantially eliminated intrinsic fouling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1600–1606, 2000     

High Serum Apolipoprotein E Determines Hypertriglyceridemic Dyslipidemias, Coronary Disease and ApoA-I Dysfunctionality

The relevance of serum apolipoprotein E (apoE) levels to two hypertriglyceridemic dyslipidemias has not been clarified. We explored, in a cross-sectional (and short-term prospective) evaluation, the independent relationship of serum apoE to the atherogenic dyslipidemia, hypertriglyceridemia with elevated apoB (HtgB) and to apoA-I dysfunctionality, previously shown in Turkish adults to be independent of apoE genotype. Serum apoE concentrations were measured by immunonephelometry in 1,127 middle-aged adults. In multivariable regression analysis, apoE concentrations showed log-linear associations with apoB and apoA-I levels, waist circumference, independent of C-reactive protein (CRP), homeostatic model assessment (HOMA) index and other confounders. The likelihood of atherogenic dyslipidemia and of HtgB roughly tripled per 1-SD increment in apoE concentrations, additively to apoE genotype, HOMA, apoA-I, CRP concentrations and waist circumference; yet apoA-I, protective against atherogenic dyslipidemia, appeared to promote HtgB, a finding consistent with apoA-I dysfunctionality in this setting. Each 1-SD increment in the apoE level was moreover, associated in both genders with MetS (at OR 1.5), after adjustment for sex, age, apoB, apoA-I and CRP, or for apoE genotypes. Circulating apoE predicted in both genders age-adjusted prevalent and incident coronary heart disease (CHD), independent of apoE genotype and CRP (OR 1.32 [95 % CI 1.11; 1.58]). To conclude, in a general population prone to MetS, elevated apoE concentrations are strongly linked to HtgB and atherogenic dyslipidemia, irrespective of apoE genotype, are associated with MetS and CHD. Excess apoE reflects pro-inflammatory state and likely autoimmune activation.     

RHX Dating of Archeological Ceramics Via a New Method to Determine Effective Lifetime Temperature

Determining the absolute chronology of ceramic artifacts has significant implications for archeological and historical research. Wilson, Hall et al. recently suggested a new technique for direct absolute dating of archeological ceramics based on a moisture‐induced chemical reaction, called rehydroxylation (RHX) dating. RHX dating proceeds by measuring the mass of chemically combined water in the ceramics in the form of OH hydroxyls, and the mass gain rate at the Effective Lifetime Temperature (ELT) that the ceramics experienced over its lifetime. To date, ELT determinations have been based on estimates of the ceramic's lifetime temperature history; taking into account weather and climate data and the depth at which the artifact was found. The uncertainty in determining the ELT can be a major component of the overall dating uncertainty. Here, we propose an alternative method which relies minimally on weather and climate data, and provides more precise determinations of the ELT and the ceramic age. The proposed method (SAS: Same Age Samples) involves a minimum of four measurements of the RHX mass gain rate constant for two ceramic samples of the same age at two temperatures. We show via simulations that the proposed SAS method can determine the ELT with a precision of 0.2 K which is comparable to the best ELT determination based on lifetime temperature history, and also comparable to available microbalance temperature resolutions of around 0.1 K. The corresponding percent age error is then 1.4%, or 43 yr for a 3000‐yr‐old ceramic. The proposed SAS method should be tested with ceramic samples of different ages, whose ELT are well‐known.     

Catalytic Combustion

Increased awareness of the problems caused by air pollution and the decrease of fossil fuel reserves have resulted in great interest in combustion techniques that reduce pollutant emission levels from combustors while simultaneously increasing combustion efficiency. The development of catalytic combustors has two primary objectives: to attain levels of NO_X emissions substantially below those possible with conventional ones, and/or to carry out stable combustion for low concentrations of fuel in air.     

Modelling the impact of crushing on the strength performance of corrugated fibreboard

This paper presents different ways of modelling the strength of corrugated fibreboard (CFB) subjected to different levels of pre-crushing. The strength performance was measured through four-point bending loading and edge crush test (ECT). The models used in this study were an analytical solution, an equivalent flute model, and detailed flute geometry models that consisted of idealized sine geometry and real geometry. The study found that the bending performance was dependent on the calliper of CFB rather than the flute geometry. All models showed a similar trend in predicting the drop in bending stiffness as the level of pre-crushing increased, albeit with different absolute value. It was found that the real geometry model of the board predicted ECT performance better than the other models. However, at severe pre-crushing levels (>50%), there was a significant drop in the experimental ECT force not predicted by the models. For these cases, there was evidence of delamination of the flute, a failure mechanism that was not included in any of the models. The analytical solution model provides the quickest prediction but could not predict the crushed ECT performance due to not considering the calliper variable in the equation. The equivalent model showed faster solving time compared with both real and idealized geometry models, although these microgeometry models predicted ECT the most accurately.