水产品香气研究进展

香气是水产品新鲜度和风味的重要评价指标,对产品品质评级及消费者消费导向均有重要影响。研究表明:挥发性化合物的种类和含量是造成水产品香气差异的主要原因,不同水产种类、新鲜程度和加工方式等均会影响其最终香气;水产品香气成分复杂,对挥发性风味物质的准确分析是研究其特征香气的关键。概述了水产品香气分析的感官品评和仪器分析技术,总结了不同水产品特征性香气物质。探讨在水产品中已发现的300余种挥发性成分(主要包括醛类、酮类、醇类、酸类、含硫化合物等)的特征性,基于分子感官科学剖析生鲜水产品、热处理及发酵等加工水产品的关键香气活性物质,发现醛类、酮类和醇类等物质赋予生鲜水产品特有的清香,而不同加工方式下的关键香气物质存在较大差异。为系统研究水产品固有香气的化学本质及其风味形成机理,应重点从分子层面揭示水产品关键香气物质的代谢途径。最后探讨了水产品基质与香气物质的相互作用以及腥味、异味的消减机制,提出现代仪器分析手段与分子感官科学结合,深入探讨水产品香气形成途径和香气释放机制等是未来水产品香气研究的重点。     

黄酒风味物质的香气强度与结构关系的研究进展

介绍了黄酒中风味物质的研究及评价方法,就黄酒中挥发性风味物质与香气强度定量关系的研究现状做了论述.从风味物质的嗅觉阈值出发,进一步阐述了黄酒中的醇、酯、酸、醛等挥发性风味化合物的香气强度与分子连接性指数之间的定量关系,并对今后黄酒的发展趋势进行了展望.     

运用气相色谱-嗅觉测量法和气质联用法分析三个桂花品种的香气活性物质

研究目的：分析不同桂花品种感官评价差异所对应的香气成分,及其有贡献的香气活性物质,为桂花的生物科学应用提供依据。创新要点：首次运用气相色谱-嗅觉测量法（GC-O）结合气质联用法（GC-MS）对所分离的挥发性物质进行定性和半定量分析,并同时结合其气味描述,分析不同桂花品种的香气活性物质特征。本研究还根据所检测的香气活性物质的气味特征对香气活性物质进行分组,能更直观地分析桂花不同品种香气差异的原因。研究方法：（1）运用GC-MS 对三个桂花品种的挥发性物质进行定性和半定量的比较分析（见表1）;（2）运用GC-O 对三个桂花品种香气活性物质进行比较分析（见表2）;（3）对香气活性物质进行分组,探究不同桂花品种的香气差异原因（见表3和图2）。重要结论：（1）GC-O 结合GC-MS 分析所得香气活性物质并非都是含量较高的挥发性物质,有些含量较低的挥发性物质也对桂花香气形成有贡献;（2）不同桂花品种的香气差异是由不同香气分组以及香气活性物质强度不同所致。     

白酒风味物质分析研究进展

白酒是有着数千年历史的传统发酵饮料,在中国的饮食文化中有非常重要的作用。系统的探讨了白酒中挥发性风味化合物和非挥发性风味化合物的分析方法,以及白酒中风味化合物相互作用的研究现状。白酒中的挥发性风味化合物之间会产生加成作用、协同作用、掩盖作用或无相互作用,分析这些相互作用的方法有很多,主要有S型曲线法、OAV法、σ-τ图法、分配系数法、矢量模型法以及PDE模型法。有研究通过S型曲线法发现烷基硫醚对酱香型白酒的水果香味有协同作用等；通过OAV法对茅台酒的研究表明:己酸乙酯与乳酸乙酯、乙酸乙酯这两组混合物分别发生了协同作用等,而乙酸乙酯和乳酸乙酯的混合物发生了加成作用等；用σ-τ图法分析了清香型白酒中醛酮类物质和醇类物质间相互作用,醇类物质基本发生掩盖作用,而己醇和苯甲醇则不发生相互作用,醛酮类物质发生协同作用等；通过分配系数法发现白酒中高浓度的2-苯乙醇和1-丙醇可以抑制3-甲基丁酸的释放,并且1-丙醇对3-甲基丁酸的影响要大于2-苯乙醇等；利用矢量模型法研究发现:混合物的香气强度与单个组分的香气强度之和存在良好的线性关系等；PDE模型法对白酒中混合物的香气强度有很好的预测性能。每种方法都有自己的优缺点,相互验证会使研究结果更准确。     

天然MnSOD活性中心的密度泛函理论研究

本文用密度泛函理论对天然MnSOD的活性中心进行了计算,从电子组态、前线分子轨道、Mulliken重叠布居和NBO分析等方面解释了天然MnSOD的活性,为MnSOD模拟化合物的分子设计提供了理论依据。     

世界6大蒸馏酒香气成分研究概况与前景展望

主要回顾了近年来国内外对世界6大蒸馏酒中香气成分分析及其对香气贡献的研究现状和进展。6大蒸馏酒所含的挥发性物质各具特色,特征香气成分也各不相同。如己酸乙酯、丁酸乙酯、戊酸乙酯、2-甲基-1-丙醇等在多数中国白酒中有香气贡献;乙酸异戊酯、苯乙醇、乙酸2-苯乙酯、异丁酸乙酯等在多数国外蒸馏酒中有香气贡献。对蒸馏酒中香气贡献的研究主要采用气相色谱-嗅闻仪结合香味提取物稀释分析、香气活性值、香气重组实验和缺失实验等,确定特征香气成分。     

白酒香气物质研究的方法学

20世纪60年代,具有酱香型白酒窖底香气的己酸乙酯从茅台酒中被成功分离鉴定,标志着我国白酒风味物质研究的开端。近年来,随着分离技术和鉴定技术的发展,白酒香气物质的研究取得了突飞猛进的发展。对白酒香气物质研究现状、新动态、新发现、新技术等内容进行综合分析、归纳讨论,提出了白酒风味物质研究的方法学,论述了白酒香气总体研究思路应包含香气物质提取、香气物质分离、活性香气化合物发现、重要活性香气化合物确认等4个部分的观点;并对香气萃取浓缩分析和Osme等方法在白酒闻香技术中的应用,直接进样和液液萃取等方法在白酒香气成分定量技术中的应用进行了评价;对白酒香气重组与缺失技术进行了专门整理;最后,指出酒类香气物质未来研究发展的可能方向。     

反应温度对以鸢尾根为原料的美拉德产物分布及卷烟加香的影响

研究了以鸢尾根为原料优化反应温度开发新型的烟用香料.用GC-MS分析方法检测了鸢尾根发酵液在不同温度(90、100、110、120℃)时美拉德反应产物的挥发性成分,并进行主成分分析,评价了不同温度下美拉德反应产物在卷烟加香中的作用. GC-MS分析结果表明:美拉德反应100℃下的样品挥发性香味成分的种类最多,为77种;挥发性成分总含量最高,达1034.37μg/g.鸢尾根发酵液美拉德反应产物中特征香气成分含量最多.将100℃时鸢尾根发酵液的MRPs在空白卷烟中加香,烟气细腻,香气丰富性显著提升,刺激性显著降低,余味较舒适.结合GC-MS和主成分分析结果表明100℃是制备具有丰富香味物质和美拉德反应特征香气成分的最佳温度.     

水果香气物质分析研究进展

香气是水果及其产品最重要的质量指标之一。保持天然风味、改善香气以及提高产品品质一直是行业追求的目标,这使得准确全面分析水果中的香气物质至关重要。由于水果基质复杂,香气化合物含量低,特别是一些关键香气物质极微量或不稳定,所以对水果香气成分的准确分析是一项复杂且困难的工作。简述了水果香气物质的提取方法和目前水果香气物质研究方向,以及关键香气物质鉴定方法,并从感知相互作用方面介绍其对水果总体香气影响的研究,最后对完善水果香气物质分析方法及研究方向趋势提出展望,以期为更好地开发高品质的水果及其加工产品提供香气研究的理论依据。     

氢键缔合水分子与水的反常膨胀探析

从水的密度、水分子结构、冰的结构、水分子间的氢键及水分子的缔合等入题,分析了对水的反常膨胀;从微冰结构、晶体结构、极性分子及分子缔合几种解释方法,认为用水分子间形成氢键缔合水分子理论解释水的反常膨胀最为科学,与实验事实及晶体理论相吻合。     

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.     

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.     

A computer generator for randomly layered structures

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

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

正~~     

An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.