预处理方式对小麦秸秆制备高吸水性树脂的影响

以小麦秸秆为原料合成高吸水性树脂需首先对秸秆进行预处理,通过实验分析,比较了预处理方式如酸处理、碱浸泡、氨水浸泡、碱蒸煮及其联合处理对秸秆及高吸水性树脂的影响;用晶相显微镜、IR等表征了处理前后秸秆的微观形貌、化学结构及树脂的化学结构等;结果表明,比较理想的预处理方式是碱蒸煮处理〔w(NaOH)=14%的水溶液、150℃、0.6 MPa、30 m in〕结合浓度为1 mol/L的硝酸在100℃下处理30 m in,及w(NH3.H2O)=10%的氨水室温浸泡48 h结合浓度为1 mol/L的硝酸在100℃下处理45 m in;两种方式所得高吸水性树脂吸收纯水的质量倍率分别为405 g/g和293 g/g,吸收w(复混肥)=0.1%的水溶液的质量倍率分别为124 g/g和82g/g〔复混肥中w(N)=w(P)=w(K)=10%,N、P、K分别以尿素、过磷酸钙、氯化钾存在〕。     

New Pretreatment for Elastomers to Enhance Adhesion

The effects of various chemical pretreatments on the surface chemistry and adhesion performance of an additive-free styrene-butadiene block copolymer and an additive-free ethylene-propylene elastomer have been studied. Most of the powerful oxidising agents that are effective with hydrocarbon plastics were ineffective in enhancing the adhesion to elastomers despite causing major changes to their surface chemistries. The poor adhesion was attributed to the existence of weak boundary layers. Chlorinated agents were also examined and a new pretreatment for elastomers containing carbon-carbon double bonds has been identified. It was found that a mildly acidified dilute aqueous suspension of Chloramine-T was very effective at enhancing the adhesion performance of styrene butadiene copolymers.     

Extraction of lipids from Yarrowia Lipolytica

BACKGROUND: Microorganisms have often been considered for the production of oils and fats as an alternative to agricultural and animal resources. Extraction experiments were performed using a strain of the yeast Yarrowia lipolytica (Y. lipolytica), a high‐lipid‐content yeast. Three different methods were tested: Soxhlet extraction, accelerated solvent extraction (ASE) and supercritical carbon dioxide (SCCO₂) extraction using ethanol as a co‐solvent. Also, high pressure solubility measurements in the systems ‘CO₂ + yeast oil’ and ‘CO₂ + ethanol + yeast oil’ were carried out. RESULTS: The solubility experiments determined that, at the conditions of the supercritical extractor (40 °C and 20 MPa), a maximum concentration of 10 mg of yeast oil per g of solvent can be expected in pure CO₂. 10% w/w of ethanol in the solvent mixture increased this value to almost 15 mg of yeast oil per g of solvent. Different pretreatments were necessary to obtain satisfactory yields in the extraction experiments. The Soxhlet and the ASE method were not able to complete the lipid extraction. The ‘SCCO₂ + ethanol’ extraction curves revealed the influence of the different pretreatments on the extraction mechanism. CONCLUSION: Evaluating the effectiveness of a given pretreatment, ASE reduced the amount of material and solvent used compared with Soxhlet. In all three cases, the best total extraction performance was obtained for the ethanol‐macerated yeast (EtM). Addition of ethanol to the solvent mixture enhanced the oil solubility. Oil can be extracted from Y. lipolytica in two different steps: a non‐selective ethanol extraction followed by TAG‐selective SCCO₂ purification. © 2012 Society of Chemical Industry     

臭氧水浓度对鳙鱼头减菌效果及鲜度品质的影响

目的 研究不同浓度臭氧水对鳙鱼头减菌效果的影响,确定鳙鱼头最佳臭氧水减菌化条件,为鳙鱼头的冰温保鲜奠定基础。方法 采用气液混合法制备不同浓度的臭氧水,通过菌落总数及TBA值、TVB-N值、K值和pH值反映臭氧水浓度对鳙鱼头减菌效果的影响。结果 高浓度臭氧水能显著提高鱼头的减菌率、降低其TVB-N值和K值(p<0.05),对TBA值及pH值无显著影响(p>0.05)。淋洗时间对鳙鱼头的减菌率有显著影响(p<0.05),对其它指标无显著影响(p>0.05)。结论 用浓度为7.8mg/L臭氧水淋洗处理鳙鱼头5min,其减菌率可达到90.43%,且TBA值、TVB-N值和K值均较低,减菌效果较好。     

SDE-GC-MS结合保留指数分析不同预处理的豆浆风味

采用同时蒸馏-气相色谱-质谱联用技术分别对未处理、微波处理、冷冻处理和超声处理后豆浆的挥发性物质进行分析,在利用NIST质谱检索库检索的基础上,结合保留指数进行定性,同时运用峰面积归一化法加苯甲醇作内标定量。结果表明：共鉴定出48 种挥发性成分,4 种预处理后的样品挥发性成分分别为28、26、30 种和33 种。不同预处理后的风味物质均以醛类、醇类、酮类、呋喃为主,醛类含量最多。结合感官评价得出冷冻处理后豆浆风味最佳。     

Effect of pretreatments and drying methods on physico‐chemical,sensory characteristics and nutritional value of oyster mushroom

This study was aimed to evaluate the effect of pretreatments and drying methods on the chemical, physico‐chemical, sensory characteristics and nutritional value of oyster mushroom. Chemical analysis of oyster mushroom (OM) showed that the values content were increased by many times when calculated on dry weight basis. Nine treatments of dried mushroom powders (DMP) were prepared using three drying methods (hot air drying, vacuum drying, and sun drying). Also, three pretreatments of each method of drying were used (untreated, blanching by steaming without or with steeped in 0.5% citric acid solution for 30 min).The results and statistical analysis revealed that, sun dried oyster mushroom samples (without pretreatments) were found to be the best. The DMP samples resulting of the sun drying had a highest physico‐chemical properties, sensory evaluation scores, and contents of the mineral elements and amino acids as compared to other pretreatments and drying methods.

Practical applications

Fresh mushrooms have high water content, high enzymatic activity and hence are highly perishable. Thus, in this study nine treatments of dried mushroom powders (DMP) were prepared using three drying methods (hot air drying, vacuum drying and sun drying).Also, three pretreatments of each method of drying were used (untreated, blanching by steaming without or with steeped in citric acid).The DMP samples (untreated) resulting of the sun drying were better than other pretreatments and drying methods regarding quality attributes.     

Characterization of Surface Pretreatments on Al/Li Alloy and Related Mechanical Properties of Polysulfone Adhesive Bonds

An investigation of polysulfone-Al/Li alloy interaction involved single lap shear joints and wedge samples following an FPL etch, sulfuric acid anodization (SAA) and phosphoric acid anodization (PAA). The study of the Al/Li surfaces involved the determination of the elemental composition and morphological features of the pretreated adherend before bonding and following fracture. When polysulfone was either thermally pressed or primed onto the microporous surface, the polysulfone indeed penetrated into the porous oxide and thereby provided a mechanical means of adhesion. The wedge test results for the adherend pretreated by PAA and SAA were superior to those for the FPL etched adherend. The failure path for the FPL etched samples was at the adhesive/oxide interface whereas the failure path for the PAA samples was within the adhesive but with occasional divergence of the crack into the oxide. The porous oxides on Al/Li alloy formed after PAA and SAA treatment were shown to undergo dramatic changes in morphology on short term (< 95 hrs) exposure to 71°C and 100% R.H. environment. The mechanism of failure was due to moisture which caused hydration and subsequent weakening of the surface oxide layer and the bonded joint. Lithium was not surface concentrated in the PAA treated Al/Li alloy as shown by AES depth profiling and therefore the effect of Li on the durability of the bonded alloy is considered minimal.     

麸皮预处理对全麦面团及面包的影响

本实验分别采用微波、烘烤、常压蒸汽、高压蒸汽对小麦麸皮进行预处理,研究比较了不同预处理方法对全麦面团和面包品质的影响。结果表明：和未处理全麦粉相比,烘烤、常压蒸汽和高压蒸汽处理均使全麦粉的稳定时间提高,其中常压蒸汽效果最显著,提高了4.2 min;同时,这三种处理方式分别使全麦面包的比容增加了6.92%、9.34%、5.19%,硬度分别降低11.81%、21.79%、19.57%,弹性分别提高2.59%、3.06%、1.65%。推测原因是这三种处理方式均显著降低了麸皮中的还原型谷胱甘肽含量,使全麦面团的游离巯基显著减少,二硫键显著增加,其中常压蒸汽和高压蒸汽效果最显著,分别使还原型谷胱甘肽减少了66.77%、69.30%,使游离巯基减少了40.43%、42.77%,使二硫键增加了51.35%、38.63%。综上,采用烘烤、常压蒸汽、高压蒸汽对麸皮预处理,可以通过降低还原型谷胱甘肽含量、提高二硫键含量来提高面团的稳定性,进而改善面包品质,且常压蒸汽处理的改善效果最好。     

Adhesive bonding of aerospace materials — surface characterization of metallic adherends

Adhesively bonded structures are widely used in the aerospace industry. Unfortunately, adhesion is a macroscopic property depending specifically upon numerous sub-microoscopic parameters so that producing a strong and durable bond is a difficult task which needs many fundamental and applied research investigations. In this context, the surface composition of adherends plays an extremely important role in the overall performance of a bonded structure: it is well known that surfaces of ‘as-received’ materials are chemically very different from the bulk composition and are usually unsuitable for adhesive bonding. Consequently, surfaces of such materials hav to be submitted to appropriate chemical or electrochemical prebonding treatments in order to modify both their morphology and chemistry.

This paper discusses the surface characterization of aluminium, titanium and their alloys at various prebonding stages. Practical applications of X-ray fluorescence spectroscopy, low-energy electron-induced X-ray spectroscopy and glow discharge optical spectroscopy are described.