HPLC法测定豆腐黄浆水中有机酸质量浓度

建立利用反相高效液相色谱法同时快速的测定豆腐黄浆水中柠檬酸、苹果酸、酒石酸、草酸、富马酸、琥珀酸6种有机酸的方法.采用Agilent Eclipse XDB-C18色谱柱;紫外检测器,检测波长为210 nm;流动相为甲醇∶0.01 mol/L KH2PO4-H3PO4缓冲溶液(3∶97,pH值为2.85);流速为0.8 mL/min;柱温为25℃;进样量为20μL.在最佳色谱条件下,柠檬酸、苹果酸、草酸等6种有机酸能同时、快速的分离.线性相关系数r0.982 4,检出限为0.555 8~1.294 8μg/mL,相对标准偏差0.13%~4.2%,该方法具有分析速度快,重现性好,精密度高,定量准确等特点.适用于豆腐黄浆水中有机酸的定量分析,对黄浆水开发利用有重要意义.     

高效液相色谱法测定市售樱桃酒中的有机酸

采用高效液相色谱法测定8种市售樱桃酒中的有机酸.以0.05 mol/L的磷酸溶液与甲醇(体积比为95∶5)在线混合作为流动相,使用Atlantis dC18色谱柱(250mm×4.6 mm,5μm)检测比较8种樱桃酒中的草酸、苹果酸、乳酸、乙酸、柠檬酸、琥珀酸、富马酸、酒石酸这八种主要有机酸的含量,回收率为78.5％～117.6％,各待测物线性相关系数R均大于0.999,最低检测限均小于1 μg/mL.检测结果可为樱桃酒的在线检测、质量控制以及新产品的开发提供依据.     

有机酸及降解条件对壳聚糖降解速度的影响

试验研究了不同有机酸及反应时间、温度、酸的浓度对壳聚糖降解速度的影响。壳聚糖在不同的有机酸中降解速度有很大差别,在草酸、柠檬酸、琥珀酸、苹果酸、酒石酸中的降解速度以草酸中为最快,苹果酸中为最慢。随反应时间延长,壳聚糖分子量减小的趋势变缓;降解速度随温度的升高而加快,在50~70℃条件下降解速度最快;随有机酸浓度的增加,壳聚糖降解速度也增加。     

不同品种桑椹中糖酸组成和甜酸风味评价

比较不同品种桑椹中的糖酸组成,并对其进行甜酸风味评价。以19 个桑椹品种的果实为试材,采用高效液相色谱法分析不同品种有机酸及糖的种类和含量,在此基础上比较各品种间的果实酸甜风味。结果表明,所有桑椹品种含有柠檬酸、酒石酸、苹果酸、琥珀酸、草酸和富马酸,部分桑椹品种含有乳酸和乙酸,含量较高的4种有机酸为柠檬酸、酒石酸、琥珀酸,苹果酸,总有机酸质量比在1687.9~2972.1mg/kg。最高的是云果1号,最低的是安杂8号。果糖和葡萄糖是桑椹的主要糖类,同一品种二者含量相当,品种之间存在差异。与糖酸比相比,采用甜度和酸度的比值构建的甜酸风味指数更能真实地反映果实的甜酸风味。从甜酸风味指数角度来考虑,以白玉王和太深1号2个品种较佳。     

苯二胺对酒石酸-丙酮双有机底物化学振荡体系的扰动

研究了邻、间、对苯二胺对酒石酸-丙酮-Mn2+-KBrO3-H2SO4双有机底物化学振荡体系的扰动.结果表明,邻、间、对苯二胺的浓度分别在5.00×10-7~3.75×10-5,1.00×10-5~1.00×10-3和5.00×10-6~1.00×10-3mol.L-1范围内时,体系振幅的变化量与所加入邻、间、对苯二胺浓度的负对数呈良好的线性关系,相关系数分别为0.999 2,0.999 0和0.998 9,最低检测限分别为2.50×10-8,1.00×10-6和5.00×10-7mol.L-1.对可能的扰动机理进行了讨论.     

泸型酒酿造过程中上层和下层酒醅的有机酸变化分析

采用高效液相色谱技术(HPLC),对泸型酒上层和下层酒醅发酵过程中的7种有机酸(丙酮酸、草酸、酒石酸、琥珀酸、乳酸、乙酸和柠檬酸)的含量变化进行分析。结果表明,上层和下层酒醅发酵结束时,7种有机酸总量分别为47. 02±0. 83 mg/g干醅和72. 18±0. 11 mg/g干醅。上层酒醅有机酸含量在整个发酵过程中缓慢增长,而下层酒醅在前21天持续较快增长,随后波动增长。乳酸、乙酸、柠檬酸为3种主体有机酸,占7种有机酸总含量的94%以上。乙酸、柠檬酸在上层和下层酒醅中的变化趋势相似,乙酸在第15～18天快速上升,然后急剧下降,之后缓慢增长;柠檬酸在第18～21天出现大幅增长,随后保持缓慢增长。     

桑色素-Al(Ⅲ)复合物测定蛋白质

采用荧光光谱技术,分析研究桑色素-Al(Ⅲ)与生物大分子的相互作用。结果表明:蛋白质对桑色素-Al(Ⅲ)体系有明显的荧光增强作用,在pH=7.7的Tris-HCl缓冲介质中,桑色素-Al(Ⅲ)复合物在520 nm处荧光强度最强,且体系荧光强度的增加与蛋白质的质量浓度在相应范围内呈良好的线性关系。蛋白质(BSA,EA)测定的线性范围分别为:5.00×10-8~3.50×10-6g.mL-1和1.00×10-8~3.00×10-6g.mL-1,检出限分别为2.6×10-9g.mL-1和2.3×10-9g.mL-1。     

鲁米诺-Cu(Ⅱ)-盐酸二甲双胍化学发光体系的研究

在Cu(Ⅱ)存在下,研究了luminol-Cu(Ⅱ)-盐酸二甲双胍化学发光体系,建立了测定盐酸二甲双胍的流动注射化学发光新方法.结果表明,在优化的实验条件下,化学发光强度与盐酸二甲双胍浓度在1.0×10-9~1.0×10-7g/mL范围内呈线性关系.该方法测定盐酸二甲双胍的检出限为5×10-10g/mL,相对标准偏差为1.1%(1.0×10-8g/mL盐酸二甲双胍溶液,n=11).该方法已用于片剂中盐酸二甲双胍含量的测定.     

毛细管区带电泳法检测丁二酸发酵液中多种低相对分子质量有机酸

运用毛细管区带电泳直接检测法,在NaH2PO4Na2B4O7缓冲液中分离草酸、甲酸、富马酸、丁二酸、柠檬酸、苹果酸、乙酸、酒石酸9种有机酸.以溴化十四烷基三甲基溴化铵(TTAB)作电渗流反向修饰剂,研究了缓冲液浓度、pH、TTAB浓度等因素对分离的影响,并对实际发酵液进行分析测定.结果表明:各有机酸加标回收率为95.9%～102.3%,该方法适用于整个发酵过程条件的优化及发酵产物的监控工作.     

ZnSe量子点增敏碱性鲁米诺-高碘酸钾流动注射化学发光法测定苯甲酸

基于在碱性介质中,苯甲酸对ZnSe QDs增敏后的碱性鲁米诺-KIO_4体系的化学发光有抑制作用,建立流动注射化学发光分析方法测定苯甲酸的含量.在最优条件下,体系化学发光强度的猝灭值与苯甲酸的质量浓度在1.0×10~(-7)~1.0×10~(-5) g/mL内呈良好的线性关系,检出限为5.7×10~(-8) g/mL(3σ).对1.0×10~(-6) g/mL的苯甲酸标准溶液平行测定10次,相对标准偏差为1.02%(n=10).该方法用于水样中苯甲酸的检测,加标回收率为92.7%~107.1%.讨论体系的化学发光机理.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the