糖醇对冻藏南美白对虾的品质保障作用

目的探讨木糖醇、甘露糖醇和异麦芽糖醇对冻藏南美白对虾的抗冻保水作用。方法以南美白对虾虾仁为研究对象,采用木糖醇、甘露糖醇及异麦芽糖醇浸泡处理虾仁,将其在-18℃条件下冻藏84 d,随后测定虾仁肌肉解冻损失率、pH值、明度、质构特性、肌原纤维蛋白含量、Ca~(2+)-ATPase活性、总巯基含量及肌肉组织微观结构。结果在冻藏过程中,与蒸馏水处理相比较,木糖醇、甘露糖醇和异麦芽糖醇浸泡处理能够有效降低虾仁的解冻损失率,且对冻虾仁的色泽、咀嚼性和弹性等具有很好的保护作用。同时,经3种糖醇处理后显著减缓了冷冻虾仁的肌原纤维蛋白含量、Ca~(2+)-ATPase活性及总巯基含量的下降速率。观察肌肉微观组织发现,3种糖醇对维持虾仁肌肉组织完整、抑制冰晶生长具有明显的作用。结论 3种糖醇类物质有效保持了冻藏南美白对虾虾仁的品质特性,可为低甜味、低热量的无磷保水剂开发提供参考。     

Cobalt-doped cerium oxide nanoparticles: Enhanced photocatalytic activity under UV and visible light irradiation

CeO₂ nanoparticles (NPs) were synthesized by coprecipitation using cerium(III) nitrate hexahydrate as the precursor and ethanol as the solvent. Different concentration of cobalt-doped cerium oxide NPs (3mol % and 6 mol %) were prepared by adding various concentrations of cobalt chloride to cerium nitrate. The as-synthesized NPs were characterized through X-ray diffraction (XRD) measurements, ultraviolet (UV)–visible spectroscopy, Photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). XRD results reveal that the as-prepared CeO₂ NPs had a face-centered cubic structure with crystallite size in the range of 5–8 nm. TEM analyses showed that the CeO₂ NPs and Co-doped CeO₂ NPs had a homogenous size distribution (sizes were within 5–12 nm). Band-edge absorption of CeO₂ NPs redshifted upon increasing the Co concentration as compared to undoped CeO₂ NPs. PL spectra reveal a peak shift of CeO₂ emission upon cobalt doping, which were due to an increase in oxygen defects localized between the Ce4f and O2p energy levels (i.e., via formation of Ce³⁺ states). Photocatalytic degradation of methylene blue in aqueous solution under UV and visible (sunlight) irradiation in the presence of pure CeO₂ NPs and of Co-doped CeO₂ NPs was investigated. The efficiency of photocatalytic degradation of CeO₂ NPs increased with the Co concentration both under UV irradiation and under visible light. Co-doped CeO₂ NPs (6 mol%) showed degradation efficiencies of 98% and 89% at 420 min of exposure to UV irradiation and to visible light, respectively.     

Viscosity change in oil/water food emulsions prepared using a membrane emulsification system

This paper reports viscosity measurements of oil/water (O/W) monodispersed emulsions of different droplet diameters obtained in a membrane emulsification system. Hydrophilic microporous glass membranes of different pore diameters were used to prepare O/W emulsions. The results showed that the droplet diameter of the emulsions varied with the average pore diameter of the membrane. The average droplet diameter was found to be about five times greater than the average membrane pore diameter. A correlation was found for the relationship between the average droplet diameter and the emulsion viscosity. As the dispersed droplet size became smaller, the total surface area of the droplets increased. Therefore, the emulsion viscosity and the relative viscosity increased. Few studies have reported the viscosity of O/W emulsions with droplet diameter of 5 μm or more and an oil phase concentration of 10 vol% or less. In the present study a correlation between the droplet diameter and the emulsion viscosity was statistically established. ©     

热处理对Ag-30Pd粉末相结构与形貌的影响

研究了热处理条件对不同方法制备的Ag-30Pd粉末的相结构与形貌的影响。结果表明,采用水合肼还原制备的Ag-30Pd共沉淀粉末,在335℃下经过油酸或氮气介质中液相或固相热处理后,粉末均朝合金化结构转变;采用抗坏血酸还原制备出的银钯合金粉初始为团聚颗粒,经400~450℃氮气气氛下热处理后,颗粒发生烧结而变得密实,结晶性提高;总体上,银钯共沉淀粉在335℃,合金粉在450℃的氮气保护下保温处理4 h后,粉末致密,粒径为1~3μm,可更好地满足银钯浆料的使用要求。     

深水水基恒流变钻井液流变特性研究

水基恒流变钻井液是一种适用于深水钻井作业的新型工作流体,目前关于该体系的报道较少。通过对一定温度压力下钻井液性能的检测以及流变模型分析,研究了水基恒流变钻井液的流变行为,并初步探索了恒流变机理。结果表明,在0.1～35.4 MPa范围内,当温度从4℃升高到65℃,黏度计读数φ₆/φ₃、动切力、塑性黏度等流变参数的变化幅度较小,分别在10～13、9～12、13～18 Pa及15～22 mPa·s范围内,且φ₆与φ₃读数随温度呈“U”型分布;在温度压力组合条件下,拟合经验流变方程的相关性排序为:宾汉塑性≈幂律＜卡森≈赫-巴≈罗-斯模型,其中双参数卡森模型的相关系数较高,且表达式简洁,适于描述水基钻井液的恒流变特性;以卡森模型为初始方程,引入T/P因子建立了高预测精度的动力学流变方程f（T,P,γ）,相对误差平均值为7.19%±4.07%,偏差极大值集中在100（ r/min）/65℃;分析了关键处理剂的分子形貌、结构及其与黏土片层的缔合作用,提出了基于分子形态的定性构效假设,揭示水基钻井液的流变稳定性本质。      

Synthesis and characterization of CePO4 nanorods via solvothermal process

One-dimensional cerium phosphate(CePO4) nanorods were successfully synthesized by a facile and simple solvothermal method at 150 ℃ for 12 h, using Ce(NO3)3·6H2O and NaH2PO4·2H2O as the starting materials. Phase and morphologie of the as-synthesized CePO4 products, characterized by XRD, FESEM, and TEM, were proved to be perfect and uniform hexagonal CePO4 nanorods with aspect ratio of more than 100. The photoluminescence(PL) spectrometer was used to investigate the optical properties of the assynthesized hexagonal CePO4 nanorods.     

石墨烯防腐涂层对油罐沉积水的防腐机制研究

目的探究石墨烯基防护涂层/碳钢体系在原油储罐沉积水中的防护机制。方法以实际原油储罐的沉积水为腐蚀介质,以自制石墨烯底漆和石墨烯面漆为防护涂层体系,采用交流阻抗谱、动电位极化曲线,结合盐雾实验探究石墨烯涂层体系在沉积水中的腐蚀行为和失效衍化机制。结果石墨烯底漆在浸泡初期对碳钢具有一定的防护效果,随着浸泡时间的延长,水分子逐渐渗透涂层,涂层逐渐失效。采用石墨烯面漆和石墨烯底漆搭配,可显著提高涂层对碳钢在沉积水中的防护性能,浸泡46 d后,涂层电阻仍为162 M?·cm。结论石墨烯底漆和石墨烯面漆涂层体系对储罐底板在沉积水中具有良好的防护性能,研究成果对油罐底板涂层防护选材具有理论指导意义。     

Supplementation with Docosahexaenoic Acid and Vitamin E Improves Hepatic Triglyceride Accumulation Induced by High-Fat Diet in Mice

The study aims to investigate the effect of combined supplementation with docosahexaenoic acid (C22:6 n-3, DHA) and vitamin E (VE) on the oxidative stress and liver triglycerides (TG) accumulation induced by high-fat diet (HFD) in mice. C57BL/6J mice are fed either a control diet or an HFD for 8 weeks. Animals are supplemented with DHA, VE, or DHA + VE, respectively. Supplementation with DHA alone shows significant improvement in oxidative stress and hepatic steatosis in mice. Supplementation with DHA significantly reduces the liver TG and total cholesterol contents, and the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, compared with the HFD. Supplementation with DHA also significantly decreases the mRNA expression level of sterol regulatory element-binding protein 1C. However, supplementation with VE alone does not show improvement in oxidative stress and hepatic steatosis. DHA + VE supply obtains a superior effect in alleviation of hepatic steatosis than DHA supplementation alone in mice fed by HFD. The efficacy of DHA potentiated by VE can be due to that VE enhances the effect of DHA in decrease of ALT and AST levels and increase of antioxidant enzyme activity and glutathione level in mice fed by HFD. Practical Applications: Supplementation with DHA significantly improves the oxidative stress and hepatic steatosis induced by HFD in mice. The efficacy of DHA in the alleviation of hepatic steatosis induced by HFD is potentiated by VE. These findings may provide a rational basis for the use of DHA and VE co-supplementation in patients with liver steatosis.