酶解鲭鱼罐头蒸煮液制备生物活性肽

以鲭鱼罐头蒸煮液为研究对象,从风味蛋白酶、中性蛋白酶和木瓜蛋白酶中筛得最佳酶为风味蛋白酶,通过单因素实验和正交试验确定风味蛋白酶的最佳酶解工艺为:5 g底物(即5 m L蒸煮液)、加酶量28.6 mg/m L、时间5 h、p H值6.0、温度50℃.按最佳工艺条件酶解,并经小分子电泳分析,证明蒸煮液主要蛋白被风味蛋白酶高效酶解;所得生物活性肽酶解液具有较好的抗氧化活性,其DPPH自由基清除活性的IC50值为31.35 mg/m L;羟自由基清除活性的IC50值为9.807 mg/m L;还原力的IC50值为7.019 mg/m L.     

乳清蛋白肽的酶法制备、分离纯化及活性评价

以抗氧化活性及蛋白质回收率为筛选指标对乳清蛋白肽酶解工艺进行优化,用层析柱对酶解液进行逐级分离纯化,并对其分子质量进行检测.研究结果表明:利用胰酶、复合风味蛋白酶、木瓜蛋白酶和碱性蛋白酶酶解制备乳清蛋白肽,最佳用酶为碱性蛋白酶、最适底物含量为4.0%、最适加酶量为8000U/g、最佳酶解时间为4h;酶解液经DEAE-52纤维素层析后得到的A组分抗氧化活性最好,其还原力为0.320 0±0.004 1,DPPH自由基清除率为6.58%±0.36%;A组分再经Sephadex G-15葡聚糖凝胶层析柱分离纯化后得到组分G,其DPPH自由基清除率为6.73%±0.083%;组分G的主要成分为分子质量378 u的肽段,其一级氨基酸组成为赖氨酸(Lys)、亮氨酸(Leu)及丝氨酸(Ser).     

超声辅助酶解法制备兔肉抗氧化肽工艺

以搅碎的兔肉末为原料，以超声辅助酶解制备抗氧化肽，对其抗氧化活性进行评价，发现抗氧化活性较好.比较不同酶制备的抗氧化肽的DPPH自由基清除率，从胰蛋白酶、碱性蛋白酶、中性蛋白酶、菠萝蛋白酶和木瓜蛋白酶中筛选出最佳用酶，利用单因素实验和响应面法优化了兔肉酶解的工艺条件.结果表明，酶解效果最好的是胰蛋白酶，在超声时间22.5 min,超声温度37℃,超声功率330 W的条件下酶解得到的抗氧化肽DPPH自由基清除率最好，为81.17%,与响应面优化实验回归模型的预测值基本一致；在此基础上制备兔肉抗氧化肽，对酶解液的ABTS、羟基自由基和超氧阴离子清除率进行检测，值分别为44.03%、94.69%和34.32%,均大于未酶解液.该研究可以为制备兔肉抗氧化肽方面提供理论依据和数据支持.     

花生分离蛋白复合酶水解工艺优化研究

探讨了超声波辅助前处理对花生分离蛋白复合酶解的影响,比较了碱性蛋白酶、木瓜蛋白酶、胰蛋白酶、胃蛋白酶、中性蛋白酶、风味蛋白酶等六种蛋白酶解物清除DPPH自由基的效果,确定碱性蛋白酶和胰蛋白酶较佳的复合比例为8∶2.在此基础上,开展响应面优化试验,以DPPH自由基清除率和水解度为指标,探讨复合酶与风味蛋白酶酶解的较佳工艺参数,并分析DPPH清除率和水解度相关性.实验结果表明,复合蛋白酶制备花生分离蛋白抗氧化肽的较佳酶解工艺为pH 8.5,温度49.36℃,酶添加量(E/S,质量分数m/m)3.40%,酶解时间203.59 min.     

鲷鱼鳞多肽的酶法制备及抗氧化活性研究

以鲷鱼鳞为原料,经物理方式处理后,采用单因素实验考察液料比、pH值、温度、酶底比及酶解时间对鲷鱼鳞酶解液水解度和DPPH自由基清除率的影响.结合响应面优化设计对酶解条件进行优化,结果在液料比为28∶1、酶底比7.0%、pH值7.3、50℃、酶解6 h条件下,所得酶解液水解度为10.35%,DPPH自由基清除率为82.33%.DPPH自由基清除、羟基自由基清除、还原力、金属螯合测试表明,酶解产物的抗氧化活性与浓度呈现剂量依赖性,具有抗氧化活性.分子量测定及氨基酸组成分析表明,酶解产物含有大量的寡肽,相对分子质量分布区间为180~1 000 u,其富含甘氨酸、丙氨酸、羟脯氨酸,且含有多种人体必需的氨基酸.     

蚕蛹抗氧化肽的制备及其体外抗氧化活性评价

为更客观地评价蚕蛹抗氧化肽的抗氧化能力, 以人工胃肠模拟液对不同蛋白酶酶解物的抗氧化能力进行评价, 优选获得最佳的制备用酶——碱性蛋白酶. 在此基础上,以蚕蛹抗氧化肽总还原能力为指标, 利用响应曲面法(response surface method, RSM)优化碱性蛋白酶制备蚕蛹抗氧化肽的最佳酶解工艺. 结果表明: 碱性蛋白酶的最佳酶解条件为pH=8.30, 加酶量为15.34 μL(1 902 U), 温度为50.47 ℃, 时间为2.45 h; 在此条件下优化预测得到的2 mg 蚕蛹蛋白/mL 酶解液的总还原能力为0.434, 蚕蛹抗氧化肽对·OH 和DPPH· 自由基的半数清除率IC50 分别为4.51 与4.24 mg/mL.     

菲律宾蛤仔木瓜蛋白酶水解物抗氧化活性研究

以菲律宾蛤仔蛋白为原料,用木瓜蛋白酶对其进行水解,采用正交实验方法研究酶解温度、酶解时间,加酶量和pH对水解度和抗氧化性的影响;通过检测羟自由基清除率、DPPH自由基清除、超氧阴离子自由基清除率和还原力评价水解物的抗氧化性。结果表明：水解度与抗氧化性之间没有正反相关系,当温度为45℃,时间为6 h,加酶量为1 500μg/g,pH为7.0时,水解度最大;温度为45℃,时间为2 h,加酶量为2 000μg/g,pH为7.0时,水解物的抗氧化活性最强;水解物对羟自由、DPPH自由基和超氧阴离子自由基均有很好的清除作用,并呈现浓度依赖性。因此,菲律宾蛤仔蛋白的木瓜蛋白酶水解物具有很好的抗氧化性。     

罗非鱼鱼鳞胶原多肽的优化制备及其生物活性研究

以罗非鱼鱼鳞为原料,采用碱性蛋白酶和胰蛋白酶复合水解,在单因素试验的基础上,采用响应面法优化酶解工艺,制备鱼鳞胶原多肽.测定胶原多肽的抗氧化活性、细菌低温保护活性、氨基酸组成及相对分子质量分布.结果显示,最适酶解条件为:底物质量浓度30.6 mg·m L-1、胰蛋白酶和碱性蛋白的加酶量分别为1.44和0.70 mg·m L-1、酶解温度50℃、pH值8.5、酶解时间6.35 h.酶解胶原多肽对DPPH自由基和羟基自由基的半数清除质量浓度(IC50)分别为2.89和3.54 mg·m L-1.经过细菌低温保护试验,当胶原多肽质量浓度为1 mg·m L-1时,嗜热链球菌的存活率达到75.6%.鱼鳞胶原肽相对分子质量分布显示,78%多肽片段的相对分子质量分布于180~2 000 u之间.氨基酸组成分析显示鱼鳞多肽富含甘氨酸、丙氨酸、脯氨酸、羟脯氨酸及天冬氨酸等,这些特定的氨基酸与胶原多肽的抗氧化活性、细菌低温保护活性相关.     

文蛤蛋白水解制备抗氧化活性肽的研究

以文蛤蛋白为原料,通过蛋白酶水解制备抗氧化活性肽.利用体外清除DPPH活性评价酶解产物的抗氧化活性,采用超滤、葡聚糖凝胶柱层析和HPLC对相应的活性肽进行分离纯化,通过HPLC-MS进行结构鉴定.结果表明:木瓜蛋白酶水解产物的DPPH清除活性明显高于碱性蛋白酶、风味蛋白酶、中性蛋白酶和复合蛋白酶,产物质量浓度为1 mg·mL-1时,DPPH清除率为55.74%;以DPPH清除率为筛选指标,对木瓜蛋白酶酶解产物进行逐级分离,得到4个具有抗氧化活性的目的肽段,氨基酸序列分别为LNFNLEKSR(1120.3 u)、SWLRPR(814.4 u)、RIGNIISQY(1063.3 u)和LNFNLEK(877.2 u).     

木瓜蛋白酶酶解豌豆蛋白挤出物产物自由基清除活性评价

以豌豆蛋白为原料,经过挤压处理得到挤出物.利用木瓜蛋白酶对其进行酶解,通过响应曲面实验对酶解条件进行优化设计.对酶解产物的抗氧化性质进行研究,得出如下结论:木瓜蛋白酶酶解最佳条件为加酶量12.1%(E/S)、温度60.6℃、pH 6.50、底物质量浓度0.071g/mL.在此条件下,DPPH清除率、·OH清除率预测值分别为98.3%、84.7%.经验证,得到最佳DPPH清除率、·OH清除率分别为98.2±0.21%、84.5±0.15%,所建模型预测准确可靠,酶解产物抗氧化性高.     

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