Synthesis and characterization of PLA nanocomposites containing nanosilica modified with different organosilanes I. Effect of the organosilanes on the properties of nanocomposites: Macromolecular,morphological, and rheologic characterization

Polylactide nanocomposites containing different loadings of nanosilica were prepared by employing bulk ring opening polymerization from lactide. Nanosilica was used as such and after surface treatment with different amounts of two distinct silanes. The effects on the properties of the material were evaluated comparing the samples containing organosilane‐modified nanosilica with poly(lactic acid) (PLA) containing unmodified nanosilica. A standard linear PLA and an industrial “film grade” PLA (PLA Natureworks 4032D) were used as reference. Pure silica tends to decrease the molecular weight of the material, deactivating the catalytic system but when silanes are present on the surface, molecular weights are similar to the ones of standard and industrial PLA. Transmission electron microscopy analysis shows that silanes improve the dispersion of the mineral, while rheologic curves suggest that when silanes are present melt viscosity increases markedly at zero shear and decreases faster as the shear rate increases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of polyamides X 18

Step heating melt polycondensation was adopted in the preparation of polyamides based on 1,16‐octadecane diacid and α,ω? (CH₂)_2n diamines (n = 1–6). The structure was confirmed by various spectroscopic techniques (IR, Raman, ¹H‐NMR, and ¹³C‐NMR). High molecular masses were obtained only in the presence of an excess of diamine and when the diamine possessed low volatility. The molecular masses were between (0.94 and 2.1) × 10⁴ Da for all polyamides under consideration. An excellent correlation between size exclusion chromatography and ¹H‐NMR data was demonstrated in the measurement of the degree of polymerization. The melting temperatures of the polyamides decreased from polyamide 12 18 to polyamide 2 18 as the amide density along the molecular chain declined. No significant variation was observed in the glass‐transition and decomposition temperatures of the polyamides that were obtained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1565–1571, 2005     

A neuro‐fuzzy computational approach for multicriteria optimisation of the quality of espresso coffee by pod based on the extraction time,temperature and blend

We demonstrate how soft computing methods can be exploited to solve multicriteria quality optimisation problems in food science and technology. In particular, we link neuro‐fuzzy modelling techniques with simulated annealing to optimise/design the quality of espresso coffee by pod. The design variables are the extraction time (ranging from 10 to 30 s), temperature (80–110 °C) and blends (100% Arabica, 100% Robusta and Arabica Robusta: A20R80, A80R20 and A40R60); they are not the only variables that affect the sensory profile of a cup of espresso coffee, but have a strong impact on the sensory quality of the beverage. Based on the framework, we show that the particular problem is a nonlinear one. Hence, an espresso coffee characterised by a specific sensory profile can be extracted using different sets of parameter values. For example, the same sensory profile can be obtained using either pure Robusta extracted at 22 s and 94 °C or 90% Arabica and 10% Robusta extracted at 25 s and 99 °C. Yet, the global optimum with respect to the distance to the optimum sensorial values is obtained using 70% Arabica and 30% Robusta extracted at 15 s around 93 °C.     

待机功耗:0.00W

开关电源领域取得的一项新进展可以使电气设备的输入功率低至0.005瓦,同时仍能对远程控制或其他上电刺激做出响应.     

Infrared spectroscopy of supported lipid monolayer, bilayer, and multibilayer membranes

A study was designed to determine the effects of triptorelin (Decapeptyl C.R.), a GnRH-agonist in a depot formulation, on androst-16-en-3-one (androstenone), LH, oestradiol and testosterone and on carcass composition and muscle structure in boars. Treatment with this highly potent GnRH analog ensured peptide release for 4 weeks when given to 18 animals at 135 days of age (group 1). Control animals (n = 20, group 2) received a saline injection. Blood samples (n = 10) were collected by venipuncture from each boar from 7 days before hormone treatment to 28 days after treatment. During the treatment period, three samples of back fat were taken by biopsy to determine the levels of androstenone and skatole. Testis size was determined at slaughter at 165 days of age. The treatment of boars with triptorelin increased concentrations of LH, oestradiol-17 beta, and testosterone for one day, followed by a decrease to base-line concentrations. The result of sensorial testing for boar taint detection at slaughter showed a slight reduction in this trait (0.76 vs. 0.99). The concentration of androstenone in the body fat of all treated animals was lower than the generally accepted limit of 0.5 microgram/g for the absence of boar taint, compared with the concentrations from 20 control animals among which 13 showed levels higher than this limit. The hormonal treatment significantly reduced the weight and size of the tests. There was no effect on skatole levels in backfat (0.141 vs. 0.150 microgram/g). The GnRH-agonist did not influence the carcass composition of treated boars. The muscle meat percentage was not significantly altered in the experimental group (51.39 vs. 50.50%). Overall, these results indicate that the use of this form of GnRH-agonist in a depot formulation offers a new possibility for reducing concentrations of androstenone which is mainly responsible for undesirable boar taint.     

Characterisation of dairy emulsions by NMR and rheological techniques

Droplet size distribution strongly affects macroscopic properties of emulsions. In this work rheological and NMR (nuclear magnetic resonance) analyses were performed to evaluate material properties as well as droplet size distribution and possible flow-induced alteration. The investigated materials were commercial dairy emulsions, based on milk, vegetable fats, a mixture of sugars, emulsifiers (hydrophilic or lipophilic) and natural stabilizers (carrageenan and guar gum). Rheological properties of three different dairy emulsions were related to the droplet size distribution obtained by NMR and dynamic light scattering (DLS) techniques. NMR seems to be a particularly useful technique because no previous sample treatment is necessary, whereas DLS requires a significant emulsion dilution that could change the droplet size distribution. Obtained results evidence the effect of two relevant ingredients (surfactants and fats) on rheological properties and droplet size distribution of tested emulsions. For sample containing sunflower oil and a hydrophilic emulsifier, rheo-NMR evidenced mechanical instabilities also confirmed by rheological tests. Comparison of results about the droplet size distribution evaluated by NMR and DLS evidenced that in this case sample dilution could affect size distribution. Finally, rheo-NMR was confirmed to be a powerful instrument capable of determining the material structure and alterations induced by the flow.     

单级功率因数校正LED驱动器

引言新的能源之星LED驱动器法规要求家用产品的功率因数(PF)达到0.7或更高,要求商用产品的功率因数(PF)达到0.9。本文将介绍一款适用于LED驱动器的极