On the linear correlation between microhardness and mechanical properties in polar polymers and blends

The tensile elastic modulus (E), yield stress (σ_Y) and microhardness (MH) of neat and binary and ternary blends of glassy semicrystalline ethylene–vinyl alcohol copolymer (EVOH), a glassy amorphous polyamide and a semicrystalline nylon‐containing ionomer covering a broad range of properties were examined. The tests were carried out on dry and water‐equilibrated samples to produce stiffer and softer materials, respectively. From the results, more accurate linear correlations were found to describe adequately the microhardness, modulus and yield stress of these strongly self‐associated polymers through hydrogen bonding. Copyright © 2003 Society of Chemical Industry     

The amylose and lipid contents,dimensions, and gelatinisation characteristics of some wheat starches and their A- and B-granule fractions

Starches isolated from 23 bread wheats (Triticum aestivum) and 26 durum wheats (T. durum) contained 26.3-30.6% (mean 29.1%) total amylose, 19.3–25.1% (mean 22.9%) apparent amylose and 783–1144mg 100g^?1 (mean 977 mg 100g^?1) lysophos-pholipids. Gelatinisation temperatures were 57.3–64.9°C (mean 61.8°C) and enthalpies 6.4–11.8 Jg^?1 (mean 9.7Jg^?1) in excess water, measured by differential scanning calorimetry. There were no correlations between any of these parameters. Starch granule size distributions were determined with a Coulter Counter and 100–channel analyser. A-granule mean volumes were 1235–2585μm³ (av. 1778), modal volumes 863–1804μm³ (av. 1264), mean diameters 13.9–16.0μm (av. 13.99), and specific surface areas 0.236–0.302m²g^?1. B-granule mean volumes were 35.4–100.4μm³ (av. 55.9), modal volumes 16.5–54.5μm³ (av. 27.7), mean diameters 3.66–5.07μm (av. 4.09), and specific surface areas 0.684–0.920m²g^?1. The B-granule contents of the starches were 12.8–34.6% (av. 27.3) by weight (sedimentation method) and 13.0–37.3% (av. 24.0) by volume (Coulter method), the latter being the more accurate method.     

罐装降脂减肥果茶生产工艺的研究

本文介绍了以各种中药材为主要原料 ,配以茶叶为辅料 ,运用先进的处理方法制备降脂减肥果茶的生产工艺、质量标准 ,并对确定生产工艺的几个主要问题进行了探讨     

Comparison of six methylation methods for analysis of the fatty acid composition of albacore lipid

Six methods widely used to produce methyl esters for the gas chromatographic determination of the fatty acid composition of a marine lipid were compared. Four acid-catalyzed methods (1% H₂SO₄: CH₃OH; 5% HCl: CH₃OH; 7% and 14% BF₃: CH₃OH) and two base-catalyzed methods [0.5M NaOCH₃: CH₃OH; (1:4) tetramethylguanidine: CH₃OH] were used.
The use of BF₃: CH₃OH (7% and 14%) gave a lower content of 18:1 n9 than the other methods and produced an artefact (2.7–3.2% of total fatty acid content) eluting between the 20:5 and 24:1 fatty acid methyl esters. No significant differences were obtained between the other four methods.
Accordingly the use of BF₃: CH₃OH for transmethylation of marine lipids is not recommended. Results obtained in the other four methods showed that all are comparable.     

克拉玛依原油中各组分的乳化性质

用沉淀法和色谱分离法将克拉玛依原油分离成沥青质，极性物和抽余油三组分，红外光谱分析表明，沥青质和极性物中存在一些含氧官能团的羧酸类或酚类以及含氮化合物，而抽余油则主要为烃类物质，因而沥青质和极性物的界面活性大于抽余油，沥青质具有较强的油包水（W／O）乳化能力，是造成克拉玛依原油W／O乳化的主要组分，极性物具有较强的水包油（O／W）乳化能力，是造成克拉玛依原油O／W乳化的主要组分，抽余油的乳化能力很弱。     

Group contributions to activity coefficients from the hard sphere expansion corresponding states theory

A new method has been developed for predicting liquid activity coefficients in ternary mixtures from group contributions. In this method, activity coefficients are obtained from the excess Gibbs free energy of mixing at constant temperature and pressure. In calculating this excess function, the constituent and mixture Gibbs free energies are each represented by an expansion about a pure reference fluid in powers of ratios of hard-sphere diameters and molecular attraction parameters. When the pure component differs from the reference by a single structural group, these ratios represent, respectively, the size contribution and the attraction contribution of this group to the thermodynamic property of the pure fluid. Contributions of intermolecular repulsion to the excess Gibbs free energy are calculated directly from hard-sphere equations of state for the mixture and pure components. The effect of polar contributions calculated by a Padé approximant is also examined. Results indicate that the method developed from the hard-sphere expansion corresponding-states theory is useful for predicting activity coefficients in ternary mixtures when unlike-pair interaction parameters are fitted to binary activity coefficient data. Furthermore, the method shows promise in providing a theoretical basis for applying group contributions to activity coefficients.Nomenclature A Residual Helmholtz free energy - C _p Constant-pressure heat capacity - H _vap Heat of vaporization - P ^s Saturated vapor pressure - R Gas constant - T Temperature - U ^HS Hard-sphere internal energy - V _c Critical volume - V ^L Liquid volume - x Dimensionless residual thermodynamic property - Z Compressibility factor - d Center-to-center distance between two touching molecules - k Boltzmann constant - n Moles - x Liquid mole fraction - y Vapor mole fraction - Volume expansivity - Liquid activity coefficient - Minimum molecular attraction potential - Isothermal compressibility - Permanent dipole moment - 3.14159... - Density - Fugacity coefficient Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Cuticular lipids of the booklouse,Liposcelis bostrychophila: hydrocarbons,aldehydes, fatty acids,and fatty acid amides

The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C₂₁–C₃₄), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C₂₈–C₄₂, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-); with a carbon number range of C₃₁–C₄₃ were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C₁₆–C₂₂ in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C_16:1, C_16:0, C_18:2, C_18:1, and C_18:0 in chain length) and three straight chain aldehydes (C₁₅, C₁₆, and C_17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.     

Separation of Triacylglycerol Species from Interesterified Oils by High-Performance Liquid Chromatography

Using a 1,3-regioselective lipase as a catalyst, soybean oil and olive oil were interesterified with the short-chain triacylglycerol tributyrin (1,2,3-tributyrylglycerol) to produce mixtures of structured triacylglycerols (SL-TAG). The SL-TAG were purified by column chromatography and analyzed by both normal-phase (silica column; NP_SIL) and reversed-phase [octadecyl silane (ODS) column] high-performance liquid chromatography (HPLC). Individual SL-TAG molecular species were detected by evaporative light-scattering detection, and characterized by mass spectrometry. NP_SIL HPLC successfully separated the newly synthesized SL-TAG into two groups of TAG: one composed of one butyryl group and two long-chain fatty acyl groups (from soybean or olive oil); the second was composed of two butyryl groups and one long-chain fatty acyl group. The SL-TAG species were further analyzed by reversed-phase HPLC which gave a more detailed separation of the TAG species present in the two SL-TAG.     

Frying quality and stability of low-and ultra-low-linolenic acid soybean oils

To determine effects of very low levels of linolenic acid on frying stabilities of soybean oils, tests were conducted with 2% (low) linolenic acid soybean oil (LLSBO) and 0.8% (ultra-low) linolenic acid soybean oil (ULLSBO) in comparison with cottonseed oil (CSO). Potato chips were fried in the oils for a total of 25 h of oil use. No significant differences were found for either total polar compounds or FFA between samples of LLSBO and ULLSBO; however, CSO had significantly higher percentage of polar compounds and FFA than the soybean oils at all sampling times. Flavor evaluations of fresh and aged (1, 3, 5, and 7 wk at 25°C) potato chips showed some differences between potato chips fried in different oil types. Sensory panel judges reported that potato chips fried in ULLSBO and aged for 3 or 7 wk at 25°C had significantly lower intensities of fishy flavor than did potato chips fried in LLSBO with the same conditions. Potato chips fried in ULLSBO that had been used for 5 h and then aged 7 wk at 25°C had significantly better quality than did potato chips fried 5 h in LLSBO and aged under the same conditions. Hexanal was significantly higher in the 5-h LLSBO sample than in potato chips fried 5 h in ULLSBO. The decrease in linolenic acid from 2 to 0.8% in the oils improved flavor quality and oxidative stability of some of the potato chip samples.