长期轮作施肥对棕壤磷素形态及转化的影响

对沈阳地区棕壤定位试验地各施肥处理土壤按Hed ley等建议的分级方法进行测定。结果表明,棕壤磷中残留态含量最高,无机磷主要以NaOH-P i和HC l-P i形态存在,有机磷主要以NaOH-Po形态存在,NaHCO3-Po在各组分中所占比例最小。施用有机肥能明显增加潜在活性有机磷(NaOH-Po)的数量。1.0mol L-1HC l浸提的Ca-P i存在着缓慢的动态转化过程,是棕壤中的潜在磷源。     

Effect of temperature and pore size on the fractionation of fresh and reconstituted buttermilk by microfiltration

The objective of this research was to evaluate the effect of temperature (7, 25, and 50 degrees C) and pore size (0.1, 0.8, and 1.4 micro m) on the separation of proteins and lipids (neutral lipids and phospholipids) during microfiltration (MF) of fresh or reconstituted buttermilk. Buttermilk was subjected to MF using a pilot-scale unit mounted with ceramic membranes. The MF runs were carried out in a uniform transmembrane pressure (UTP) mode. Changes in processing temperature had no significant impact on protein transmission, whereas increasing temperature reduced both lipid and phospholipid transmission. A maximum concentration factor (CF) for lipids was reached at 25 degrees C, as protein CF remained essentially unaffected by temperature. The use of the smaller pore size (0.1 microm) resulted in low lipid (10%) and protein (approximately 20%) transmission. Larger pore sizes (0.8 and 1.4 microm) resulted in higher levels of protein, lipid, and phospholipid transmission (>50%), but gave high permeation fluxes. Transmission of both proteins and lipids was markedly different when using fresh buttermilk as opposed to reconstituted buttermilk. This study showed that MF temperature, pore size, and buttermilk type influence fractionation but that MF alone cannot achieve optimal separation of lipids and proteins for the production of novel ingredients from buttermilk.     

An efficient method for the enrichment of the arachidonic acid methyl ester from Mortierella alpina-derived crude oils

An improved method was developed for enriching arachidonic acid (AA) methyl ester from microbial oil by two-step low-temperature wet fractionation. The effects of solvent, operating temperature, and solvent-to-fatty acid methyl esters (FAMEs) ratio on the enrichment of AA were investigated. The best results were achieved when n-hexane was used as solvent. With operating temperatures in the range ?30 °C to ?80 °C and a FAMEs-to-solvent ratio of 1:5 (v/v), the proportion of AA methyl ester isolated could be increased to 83.76 ± 2.78% with a yield of 52.89%. The total recovery of AA methyl ester would be further increased to 90.84% by recrystallization of the solid phases. The 20C, 22C saturated fatty acids were enriched by n-hexane or petroleum ether at ?30 °C, with concentrations increased 7.5-fold or 7.2-fold compared with their original levels, respectively. In addition, a method that combined alkali and acid catalysis of the transmethylation was the most conducive to the preparation of polyunsaturated fatty acid methyl esters.     

Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique

Supercritical carbon dioxide (SC–CO₂) fractionation technique was evaluated as an alternative process for reducing the free‐fatty‐acid (FFA) content and minimizing the phytosterol loss of rice bran oil (RBO) during the process. The effects of pressure (20.5 to 32.0 MPa) and temperature (45 to 80 °C) for isothermal operation of the column on the composition of the resultant fractions were examined. Low‐pressure and high‐temperature conditions were found to be favorable for minimizing triglycerides (TG) and phytosterol losses during the FFA removal from crude RBO. Rice bran oil fractions with < 1% FFA, about 95% TG, and 0.35% free sterol with 1.8% oryzanol content could be obtained utilizing the described SC–CO₂ fractionation technique.     

Purification and identification of a novel cutinase from Coprinopsis cinerea by adsorptive bubble separation

A novel extracellular esterase was separated from culture supernatants of the basidiomycete Coprinopsis cinerea by means of foam fractionation. The parameters pH value, gas flow rate, addition of detergents, and the column design were varied to optimise the transport of the active enzyme into the foam phase. On the 70-mL scale, a recovery of activity of 79% with an enrichment factor of 10.5 was obtained at pH 7 and 20 mL air min⁻¹ within 15 min. The enriched enzyme was characterized biochemically by semi-native SDS-PAGE and IEF electrophoresis with activity staining. Peptide sequencing was performed after tryptic digestion by electrospray tandem mass spectrometry. Homology searches revealed significant similarities to cutinases of various ascomycetes and to C. cinerea genome data recently annotated as cutinases.     

Application of microfiltration to egg white depleted in ovomucin

Summary An attempt was made to reduce the microbial load of unpasteurized fresh egg white by using cross-flow microfiltration and a Tetra-Laval bactocatch installation. Cross-flow tangential microfiltration of liquid fresh egg white was not feasible as there was irreversible membrane clogging within a few minutes of operation. As membrane clogging could have been caused by ovomucin, this protein was removed from whole fresh egg white by increasing the salt strength and lowering the pH. Ovomucin-depleted egg white (ODEW) was successfully microfiltered on the same membrane. Compared to fresh egg white, ODEW had lower foaming and viscous properties, and these properties remained unchanged after bactofiltration. The reduction of microbial load was, however, relatively low.     

基于超临界流体萃取的悬浮床加氢尾油的分离与评价

 用超临界流体萃取分馏(SFEF)装置将克拉玛依渣油悬浮床加氢尾油（KMHR）分离为8个窄馏分和萃余残渣。测定并计算了馏出油的残炭及杂质脱除率，考察了窄馏分SARA族组成、残炭、密度、硫、氮、金属及平均结构参数等的递变规律，预测了窄馏分的裂化性能，并用XRD表征了甲苯不溶物的存在形态。结果表明，超临界流体萃取可以脱除尾油中全部沥青质及甲苯不溶物，质量分数99.5％以上的金属和70.4％以上的残炭富集到萃余残渣中。馏出油符合催化裂化或加氢裂化进料要求并具有优良的裂化性能。     

Food applications of trans fatty acid substitutes

The review outlines the increasing need to reduce trans fatty acids, and addresses the functionality issues of various trans free solutions through discussion of hydrogenation, interesterification, and fractionation, and their influence on fat crystallisation and solid fat content. Caution is urged not to focus solely on physio‐chemical aspects, but to approach trans free designing for specific food applications from a multidisciplinary angle. Examples of specific applications; margarines, shortenings and frying oils are given. The review also offers a glimpse into what the future trans free trends may hold.     

Base‐Catalyzed Depolymerization of Lignin: Separation of Monomers

In our quest for fractionating lignocellulosic biomass and valorizing specific constitutive fractions, we have developed a strategy for the separation of 12 added value monomers generated during the hydrolytic based‐catalyzed depolymerization of a Steam Exploded Aspen Lignin. The separation strategy combines liquid‐liquid‐extraction (LLE), followed by vacuum distillation, liquid chromatography (LC) and crystallization. LLE, vacuum distillation and flash LC were tested experimentally. Batch vacuum distillation produced up to 4 fractions. Process simulation confirmed that a series of 4 vacuum distillation columns could produce 5 distinct monomer streams, 3 of which require further chromatography and crystallization for purification.     

溶解无机碳在地下水中的应用

碳同位素广泛分布于自然界水体中,在降水、地表水、地下水相互转化过程中,同位素分馏作用导致不同水体中具有不同的同位素含量。本文就以位于不同碳酸盐地形的泉为例进行研究,确定区域所处的环境。