利用Turbiscan多重光散射技术评价pH值与钙离子对脱脂乳的热稳定性的影响

热稳定性直接影响牛乳的加工与感官特性，准确判断牛乳的热稳定性对优化液态乳制品的加工条件具有重要意义。然而，当前液态奶的稳定性评价主要是通过加速实验后肉眼观察分层、沉淀等情况，以及动态光散射等手段，尚无快速可靠以及量化的评价标准，严重制约了热处理工艺的选择效率。Turbiscan多重光技术在测试流体的稳定性时，无需对样品进行前处理，可实时检测样品的背向散射光和透射光的强度，计算出体系内部颗粒的迁移速率、沉淀层的厚度、体系的不稳定指数等参数，因此是评价流体物理特性的有效手段。研究以动态光散射测试结果为对照，利用Turbiscan多重光技术测定了脱脂乳经过80 ℃条件下加热30 min后，分别在pH值6.3，6.5，6.7和6.9，CaCl₂的浓度在0，20，40，60和80 mmol·L-1条件下的热稳定性。结果表明，当CaCl₂添加量为20，40，60和80 mmol·L-1时，脱脂乳的z-平均直径从152.7增加到1 284.4 nm，20 h后的不稳定指数值从0.98增加到17.04，样品顶端的背散射光强变化值从-4.3降低到-37.4，底端的背散射光强变化值从2.2增加到14.7；当样品的pH值分别为6.3，6.5，6.7和6.9时，脱脂乳的z-平均直径分别为148.1，152.7，132.4和122.4 nm，20 h后的不稳定指数值分别为1.32，1.02，0.98和1.41，样品顶端的背散射光强变化值分别为-3.1，-4.7，-4.2和-5.6，底端的背散射光强变化值分别为5.7，3.4，4.1和6.8。结果表明，随着CaCl₂添加量的增加，脱脂乳的热稳定性显著降低，pH值对脱脂乳热稳定性的影响较小。同时发现，与动态光散射技术相比，Turbiscan多重光散射技术可更精确、方便、快捷地获得热处理后的牛乳背散射光强值和体系不稳定指数等牛乳稳定性指标，从而明确热处理导致的乳蛋白分散体系的不稳定性发生的机理。Turbiscan多重光散射技术比动态光散射技术测定更方便快捷，该研究对优化乳制品加工工艺具有重要指导意义。     

利用多重光散射技术研究吡虫啉悬浮剂的物理稳定性

Turbiscan Lab稳定性分析仪利用多重光散射技术,能够准确测量乳状液、悬浮液等沉淀层、浮油层或澄清层厚度以及粒子平均粒径随时间的变化情况,定性定量分析体系不稳定性发生的机理和速率。本文利用Turbiscan Lab稳定性分析仪测定了不同萘磺酸盐分散剂GY-D10,NNO,Morwet D-425,TERSPERSE 2425制备的350 g·L-1吡虫啉悬浮剂及其悬浮液背散射光强度随时间的变化情况以及颗粒平均粒径的聚结增大速率,同时利用激光粒度分析仪测定加速试验前后颗粒平均粒径的变化情况,结果表明：添加分散剂GY-D10,用量为4 Wt%时悬浮液的稳定性最好,对应的吡虫啉悬浮剂的稳定性也最好。     

蔗糖对酪蛋白结构及其乳化性影响的光谱学分析

酪蛋白酸钠作为一种良好的乳化剂和乳化稳定剂,对乳饮料品质具有重要的作用。蔗糖作为甜味剂,可以提高乳饮料的口感。但酪蛋白结构和性质很容易受到其所处的微环境的影响,为了分析蔗糖对酪蛋白酸钠结构及其乳化性的影响,利用荧光光谱技术探讨了酪蛋白酸钠荧光光谱和表面疏水性的变化,利用动态光散射技术分析了酪蛋白酸钠乳液液滴流体力学直径的变化,利用Turbiscan光谱学稳定性测试评价了酪蛋白酸钠乳液的背散射光强度变化以及稳定性指数(TSI)。结果表明：蔗糖会使酪蛋白酸钠发生内源荧光猝灭,猝灭速率常数K_S＜2.0×1010 L·mol-1·s-1,属于动态猝灭,未形成稳定的基态配合物,表明两者仅以较弱的氢键和疏水相互作用结合。酪蛋白酸钠的表面疏水性显著增强(p＜0.05),部分酪蛋白酸钠聚集程度增加,形成了可溶性聚集体。随着蔗糖浓度的增加,酪蛋白酸钠乳液流体力学直径增大,是高压均质时蛋白聚集体在油水界面上优先吸附的结果。背散射光强度结果显示随着蔗糖浓度的增加,乳液越不易产生分层、浓度变化、乳滴迁移等不稳定性现象。稳定性指数显著增大(p＜0.05),乳液稳定性增强。     

Turbiscan多重光散射法研究纳米银溶胶的分散稳定性

以硝酸银为银源、间苯二酚为还原剂、聚乙烯吡咯烷酮为保护剂通过化学还原法制得纳米银颗粒,通过离心洗涤等操作洗掉多余的反应物,将其分别超声分散于水、无水乙醇和乙二醇中获得0.2 Wt%不同体系的纳米银溶胶。利用激光粒度分析仪、透射电子显微镜、扫描电子显微镜和同步热分析仪对纳米银颗粒进行表征并测定纳米银溶胶中的银含量。激光粒度分析仪的粒度分析结果表明,实验制得的纳米银颗粒的粒径在100 nm左右,且粒径分布均一。透射电子显微镜和扫描电子显微镜的结果进一步证实纳米银颗粒的粒径在纳米尺度范围且粒径均匀。采用Turbiscan多重光散射法研究了不同体系纳米银溶胶的分散稳定性,分析了导致纳米银溶胶不稳定的主要因素。研究发现：影响纳米银溶胶分散稳定性的主要因素包括颗粒粒径的变化和颗粒的迁移。对于水相体系,样品池中间部分背散射光强度随时间变化不大,样品池底部和顶部背散射光强度有较大变化,说明其稳定性的主要影响因素是纳米银颗粒的迁移,颗粒粒径变化影响不大;对于乙醇和乙二醇体系,样品池中间部分、底部和顶部的背散射光强度均有明显变化,说明颗粒粒径的变化和颗粒的迁移对体系稳定性均有一定程度的影响;最后通过比较三个体系的稳定性动力学指数,得到体系稳定性由高到低依次为乙二醇、水和乙醇。     

苯-水混合液体的乳化机理研究

 以研究液体混合材料的冲击压缩状态方程和高温高压条件下的相变机理为最终目标，测量了在常态下苯-水-乳化剂三元样品均匀混合的表面张力、稳定性和粒度分布等量化指标，并讨论了不同制备方法对乳状液性质的影响。实验数据表明，苯-水-乳化液属于热力学不稳定体系；表面张力介于苯和水的张力之间，但不等于二者的简单平均，这与文献值一致；苯-水-乳液的制备、存储和使用环境温度不易超过53 ℃；用超声波处理后的乳液粒度分布区域变窄，但平均粒度变化不明显。本研究为解决液体混合物、特别是难于互溶的多元液体物质爆轰实验样品初始状态的量化难题提供了可靠的数据，对类似实验的制样也具有参考价值。     

火焰原子吸收光谱法间接测定烟草中的烟碱含量

基于盐酸介质中雷氏氨盐的室温下与烟碱定量形成难溶配合物的性质，采用火焰原子吸收光谱法测定反应体系中变化的铬量，根据反应计算出样品中烟碱的含量。方法用于测定烟草中的烟碱含量，回收率91.6%－105.5%，相对标准偏差1.4%-5.2%，结果满意。     

微乳液进样-石墨炉原子吸收光谱法测定生物柴油及其原料菜籽油中铅含量

生物柴油作为一种替代能源,以其良好的可再生性和环境友好性受到世界各国的关注,同时燃料中铅污染也日益引起人们的重视,因此测定生物柴油及其原料菜籽油中铅的含量具有重要的意义.建立了微乳液进样-石墨炉原子吸收法测定油样中铅含量的新方法.以聚乙二醇辛基苯基醚为乳化剂,正丁醇为助乳化剂,NH4H2PO4为基体改进剂,研究了微乳液的稳定性和微乳化剂配比对测定结果的影响,优化了石墨炉原子吸收光谱法测定条件.研究表明,当20%聚乙二醇辛基苯基醚:正丁醇:油样:水相:0.1:8.9:0.5.0.5(ψ)时,体系能形成稳定的微乳液.本方法的检出限为126.2μg·L-1,样品平均回收率在81.8%～109.0%之间,相对标准偏差为5.84%.该法用于实际油样的测定,结果令人满意.     

用扫描式电感耦合等离子体光谱仪测定红矾钾产品中的杂质

应用电感耦合等离子体发射光谱法测定了铬盐清洁工艺红矾钾产品中的微量元素硅、铝、铁、钙、锰、镁和氯。采用基体匹配法消除了大量基体的干扰。实验的优化条件为RF发生器的入射功率095kW;载气压力013MPa,流量12L·min-1;辅助气流量02L·min-1。元素氯用氯化银沉淀间接测定,在6%的硝酸体系中氯离子形成氯化物完全沉淀,在50℃陈化2h后进行测定。样品的加标回收率在90%～104%,RSD<4%,检出限在10-4%～10-5%。随机抽样的分析结果与标准加入法吻合较好,相对误差在-427%～ 526%。本方法用于实际样品分析,快速简单,结果令人满意。     

二极管泵浦无机液体激光器出光实验研究

 为探索新的高能激光体系，搭建了二极管泵浦的液体激光器。采用激光二极管作为泵浦光源，单侧泵浦掺钕离子的无机激光液体，进行了出光实验。通过测量输出光束的近场分布、脉冲波形和光谱，证实实现了激光输出，输出激光的波长为1 053 nm。输出的单脉冲激光能量达到47 mJ，光-光转换效率达到14%。其光-光转换效率高出闪光灯泵浦液体条件下2个数量级，说明该激光体系具有向高能激光体系发展的前景。     

乙基甲基咪唑磷酸二甲酯+甲醇/乙醇+水三元工质溶液比热容的测量及关联

采用绝热量热法测量了由离子液体1-乙基-3-甲基咪唑磷酸二甲酯[Emim][DMP]分别与CH_3OH+H_2O和C_2H_5OH+H_2O构成的两组三元工质溶液体系[Emim][DMP](1)+CH_3OH(2)/C_2H5OH(2)+H_2O(3)在常压、温度范围为298.01~323.34 K、不同浓度下的比热容。采用多项式函数对实验数据进行拟合,获得模型方程中的拟合参数。比热容的计算值与实验值的平均相对偏差分别为0.49%和0.80%。     

Exploring the influence of ultrasound on the antibacterial emulsification stability of lysozyme-oregano essential oil

A lysozyme-oregano essential oil (Lys-OEO) antibacterial emulsion was developed via ultrasonic treatment. Based on the general emulsion materials of ovalbumin (OVA) and inulin (IN), the addition of Lys and OEO successfully inhibited the growth of E. coli and S. aureus, two representatives of which were Gram-negative and Gram-positive bacteria respectively. The emulsion system in this study was designed to compensate for the limitation that Lys could only act on Gram-positive bacteria, and the stability of the emulsion was improved using ultrasonic treatment. The optimal amounts among OVA, Lys and OEO were found to be the mass ratio of 1:1 (Lys to OVA) and 20% (w/w) OEO. The ultrasonic treatment at the power of 200, 400, 600, and 800 W and time length of 10 min improved the stability of emulsion, in which the surface tension was below 6.04 mN/m and the Turbiscan stability index (TSI) did not exceed 10. The multiple light scattering showed that sonicated emulsions were less prone to delamination; salt stability and pH stability of emulsions were improved, CLSM image showed emulsion as oil-in-water type. In the meantime, the particles of the emulsions were found to become smaller and more uniform with ultrasonic treatment. The best dispersion and stability of the emulsion were both achieved at 600 W with a zeta potential of 7.7 mV, the smallest particle size and the most uniform particle distribution.     

紫外分光光度法直接测定废水中微量油的研究

目前 ,环保或其他部门对废水、气中的油的测定 ,一般采用石油醚萃取的重量法、红外或紫外分光光度法[1～ 5] 。因均需除去水分 ,步骤较繁琐。本法根据植物油在紫外区 2 0 0nm附近有强吸收 ,采用在废水中加入S T混合乳化剂进行乳化后 ,直接用紫外分光光度法测定其混合油的含量。方法简便快速 ,稳定性好 ,回收率在 89%～ 12 9%之间 ;线性范围为 :0～ 92 μg·mL-1。     

Fabrication of ZnO:Mn nanoparticles with organic shell in a highly alkaline aqueous environment

Synthesis of undoped and Mn doped ZnO nanoparticles by an inclusive co precipitation method and in situ capping with heteromultifunctional organic stabilizer mercaptosuccinic acid (MSA) in a core shell structure, in highly alkaline aqueous matrix have been accomplished. Near room temperature synthesis resulted in high quality monophasic wurtzite hexagonal structure of rod shaped nanoparticles of bare ZnO:Mn with no signature of dopant as separate phase. MSA capping resulted in nanoball like formation. Thermo gravimetric analysis (TGA) and FTIR confirmed MSA capping. ZnO: Mn particles emit in orange and red when excited by UV and blue light. Surface modification makes the nanoparticles hydrophilic with active organic surface easy for bioconjugation with any ligand and can have applications in drug delivery or as nanoscale fluorescent probe in a biological system.     

水溶性硫化铅纳米粒子的合成及应用于汞离子检测

室温下以柠檬酸三纳为稳定剂,在水相中合成了PbS纳米粒子（NP-PbS）。用共振光散射技术（RLS）探索了最佳条件下,体系RLS强度（IRLS）与汞离子浓度在0.001—10μmol/L测定区间内呈现良好的线性（r=0.9941）,据此,建立了测定水中的微量汞的方法。方法的检出限为0.6nmol/L,样品加标平均回收率为100.35%。     

Linear Stability of Taylor-Couette Flows with Axial Heat Buoyancy

The linear stability is studied of flows confined between two concentric cylinders, in which the radial temperature gradient and axial gravity are considered for an incompressible Newtonian fluid. Numerical method based on the Petrov-Galerkin scheme is developed to deal with the buoyancy term in momentum equations and an additional temperature perturbation equation. Computations of the neutral stability curves are performed for different rotation cases. It is found that the flow instability is influenced by both centrifugal and axial shear instabilities, and the two instability mechanisms interact with each other. The outer cylinder rotation plays dual roles of stabilizer and destabilizer under different rotating stages with the inner cylinder at rest. For the heat buoyancyinduced axial flow, spiral structures are found in the instability modes.     

Improvement of structural,physicochemical, and rheological properties of porcine myofibrillar proteins by high-intensity ultrasound treatment for application as Pickering stabilizers

This study aimed to evaluate the potential of time-dependent (0, 15, 30, 60, 120 min) treatment of porcine-derived myofibrillar proteins (MPs) with high-intensity ultrasound (HIU) for utilizing them as a Pickering stabilizer and decipher the underlying mechanism by which HIU treatment increases the emulsification and dispersion stability of MPs. To accomplish this, we analyzed the structural, physicochemical, and rheological properties of the HIU-treated MPs. Myosin heavy chain and actin were observed to be denatured, and the particle size of MPs decreased from 3,342.7 nm for the control group to 153.9 nm for 120 min HIU-treated MPs. Fourier-transformed infrared spectroscopy and circular dichroism spectroscopy confirmed that as the HIU treatment time increased, α-helical content increased, and β-sheet decreased, indicating that the protein secondary/tertiary structure was modified. In addition, the turbidity, apparent viscosity, and viscoelastic properties of the HIU-treated MP solution were decreased compared to the control, while the surface hydrophobicity was significantly increased. Analyses of the emulsification properties of the Pickering emulsions prepared using time-dependent HIU-treated MPs revealed that the emulsion activity index and emulsion stability index of HIU-treated MP were improved. Confocal laser scanning microscopy images indicated that small spherical droplets adsorbed with MPs were formed by HIU treatment and that dispersion stabilities were improved because the Turbiscan stability index of the HIU-treated group was lower than that of the control group. These findings could be used as supporting data for the utilizing porcine-derived MPs, which have been treated with HIU for appropriate time periods, as Pickering stabilizers.     

吲哚-3-丁酸无保护流体室温燐光和胶束增稳室温燐光性质的比较

仔细研究了吲哚-3-丁酸(IBA)的无保护流体室温燐光(NP-RTP)及以高分子分散剂聚乙二醇-200,聚乙二醇-400和非离子表面活性剂Tween-20,Tween-40, Tween-80,Tween-85,Brij35和乳化剂OP为介质的流体室温燐光性质。表面活性剂和高分子分散剂能抑制IBA燐光猝灭,使其具有更低的检出限,同时也使燐光强度-激发光照射时间曲线发生改变,但不影响IBA燐光光谱特性。无论是否存在表面活性剂或高分子分散剂,TlNO₃都不能诱导IBA产生燐光,KI却能诱导其产生强烈燐光。用于强化水样和土壤样品中IBA的测定,回收率95.2%～104%,相对标准偏差2.4%～4.0%。