窄安全密度窗口重力置换漏喷函数研究

由于重力置换的原因,钻遇裂缝性地层时,井下经常发生漏喷同存,造成井下复杂情况,增大井控难度,损害地层,影响生产。建立了重力置换数学模型,并基于此形成了高压含气层窄安全密度窗口重力置换漏喷函数,利用地层井筒耦合流动可视化实验装置对漏喷函数进行了验证。实验结果表明,建立的漏喷函数的计算结果与实验数据吻合度较高。当钻遇裂缝性地层时,无论是采用欠平衡钻井、平衡钻井工艺,还是过平衡钻井工艺,均无法避免重力置换现象的发生,但是将井筒压力维持在近平衡(微过)状态,能够显著降低重力置换现象的严重程度。研究成果对研究钻遇裂缝性地层时的井底复杂的物质交换规律及井筒压力的安全控制具有重要的指导意义。

基于分子对接的反向虚拟筛选方法

基于分子对接的反向虚拟筛选方法在药物靶点确定、老药新用以及药物副作用/毒理研究领域具有重要的应用前景,吸引了药物发现领域研究人员的广泛关注.首先对分子对接方法和蛋白质数据库进行细致的介绍,然后列举目前可以用于反向虚拟筛选的网络服务器,并列举该方法在药物设计领域的一些具体应用,最后对该方法目前所存在的问题进行讨论.

激光针刀对椎动脉型颈椎病模型兔椎动脉磷脂酰肌醇3-激酶mRNA表达的影响

目的探讨激光针刀对椎动脉型颈椎病(CSA)模型兔椎动脉磷脂酰肌醇3-激酶(PI-3K)mRNA表达的影响。方法建立家兔CSA模型,采用随机数字表法将造模成功的30只CSA模型兔分为模型组、针刺组和激光针刀组,每组10只,另取10只正常家兔为正常组。针刺组兔给予针刺"风池穴"、"颈夹脊穴"治疗,激光针刀组兔给予第五颈椎棘突旁夹脊穴激光针刀治疗,模型组和正常组仅给予相同的固定,实验前后观察各组家兔行为学体征,分别于造模前1天、造模后第14天(治疗前)、24天(治疗10天后)、34天(治疗20天后)称取兔体质量。采用实时荧光定量PCR检测各组兔椎动脉血管PI-3K mRNA表达情况。结果治疗后针刺组和激光针刀组兔行为学体征有不同程度的改善。与正常组比较,造模后14天,模型组、针刺组和激光针刀组兔体质量显著降低[(2.49±0.12)kg、(2.48±0.13)kg、(2.48±0.10)kg比(2.62±0.13)kg,P均<0.05];造模后24天、34天,模型组兔体质量均明显低于正常组[(2.42±0.13)kg比(2.69±0.13)kg,(2.37±0.12)kg比(2.77±0.14)kg,P均<0.01]。与模型组比较,造模后24天、34天,针刺组、激光针刀组兔体质量明显增加[(2.57±0.13)kg、(2.56±0.09)kg比(2.42±0.13)kg,(2.66±0.12)kg、(2.67±0.11)kg比(2.37±0.12)kg,P<0.05或P<0.01]。与正常组比较,模型组兔颈动脉PI-3KmRNA表达量明显低于正常组[(1.15±0.17)比(1.59±0.19),P<0.01),与模型组比较,针刺组和激光针刀组兔颈动脉PI-3KmRNA表达明显上调[(1.89±0.42)、(2.16±0.48)比(1.15±0.17),P<0.05或P<0.01),针刺组与激光针刀组比较,差异无统计学意义(P>0.05)。结论激光针刀能有效干预CSA模型兔椎动脉PI-3KmRNA表达。

Microcalorimetric Study on the Germination of Seeds

The power-time curves of the germination of different rice and tree seeds have been studied by using a microcalorimeter set up by ourselves. Some characteristic values have been obtained from these curves in different thermogenesising stages of the germination of rice and tree seeds. These parameters can be used in comparison of character and activity for different seeds,moreover the effects of different strain.germinating shape and temperature on the power-time curves of the germination of seeds have been discussed.

A simulation method of combinding boundary element method with generalized Langevin dynamics

A new simulation approach to incorporate hydration force into generalized Langevin dynamics (GLD) is developed in this note. The hydration force determined by the boundary element method (BEM) is taken into account as the mean force terms of solvent including Coulombic interactions with the induced surface charge and the surface pressure of solvent. The exponential model is taken for the friction kernel. A simulation study has been performed on the cyclic undecapeptide cyclosporin A (CPA). The results obtained from the new method (GLDBEM) have been analyzed and compared with that obtained from the molecular dynamics (MD) simulation and the conventional stochastic dynamics (SD) simulation. We have found that the results obtained from GLDBEM show the obvious improvement over the SD simulation technique in the study of molecular structure and dynamic properties.

A holistic molecular docking approach for predicting protein-protein complex structure

A holistic protein-protein molecular docking approach,HoDock,was established,composed of such steps as binding site prediction,initial complex structure sampling,refined complex structure sampling,structure clustering,scoring and final structure selection.This article explains the detailed steps and applications for CAPRI Target 39.The CAPRI result showed that three predicted binding site residues,A191HIS,B512ARG and B531ARG,were correct,and there were five submitted structures with a high fraction of correct receptor-ligand interface residues,indicating that this docking approach may improve prediction accuracy for protein-protein complex structures.

A novel family of green ionic liquids with surface activities

Ionic liquids have many unique properties as a new and remarkable class of environmental benign solvents,which promises widespread applications in industry and other areas. However,the ionic liq-uids with surface activity are rarely reported. In this work,a series of novel ionic liquids was synthe-sized by using N-methyl-2-pyrrolidone and alkyl bromide. The physical properties of this family of ionic liquids have been characterized,which shows that these compounds have ionic liquids characteristics,surface activity and biocompatibility.

Pharmacophore and Docking-based 3D-QSAR Studies on HIV-1 Integrase Inhibitors

Integrase（IN） plays an essential role in the process of HIV-1 replication.IN inhibitors of diketo acid derivatives（DKAs） were analysed by the Comparative Molecular Field Analysis（CoMFA） and Comparative Molecular Similarity Induces Analysis（CoMSIA） methods.A set of 42 compounds were randomly selected as the training set（35） and test set（7）.Firstly,a good pharmacophore（goodness of hit=0.787） was obtained and used to align ligands.Then,predictive models were constructed with the CoMFA and CoMSIA methods based on the pharmacophore alignment.As a result,the CoMS1A method yielded the best model with an r2 of 0.955 and a q2 of 0.665,which can predict the activities of the tested DKAs very well（r2=0.559）.Finally,DKAs were docked into IN,and the predicit modes were superimposed on the contour maps obtained from the best CoMSIA model.The superimposed maps gave a visualized and meaningful insight into the inhibitory behaviors,providing significantly useful information for the rational drug design of anti-IN agents.

Salt and pH-dependent properties of native and mutant insulin

A fast and effective model for predicting the salt and pH dependent properties of protein complexes is presented. It is based on the formal charge parameter sets of ionizable groups and applied in conjunction with the finite difference Poisson-Boltzmann (FDPB) method to calculate the electrostatic interactions. All simulations were performed on the native 2Zn insulin and its fast-acting mutants such as B9D (B9Ser→Asp), B9E (B9Aer→Glu), B9EB10D (B9Ser→ Glu, B10His→Asp), and B10D (B10His→Asp). The salt and pH dependent properties of these dimers were analyzed from the aspect of electrostatic interaction, and the theoretical basis of the fast-acting behavior of these mutants was explained. It is found that the results agree well with experimental observations.

Improvement of the relative entropy based protein folding method

The "relative entropy" has been used as a minimization function to predict the tertiary structure of a protein backbone, and good results have been obtained. However, in our previous work, the ensemble average of the contact potential was estimated by an approximate calculation. In order to improve the theoretical integrity of the relative-entropy-based method, a new theoretical calculation method of the ensemble average of the contact potential was presented in this work, which is based on the thermodynamic perturbation theory. Tests of the improved algorithm were performed on twelve small proteins. The root mean square deviations of the predicted versus the native structures from Protein Data Bank range from 0.40 to 0.60 nm. Compared with the previous approximate values, the average prediction accuracy is improved by 0.04 nm.

Investigation of Thermal Decomposition of Ascorbic Acid by TG-FTIR and Thermal Kinetics Analysis Shi Jingyan

The thermal behavior of dry solid ascorbic acid in nitrogen atmosphere in the temperature range of 25800℃was investigated by TG-FTIR.During the thermal decomposition process,five evolved gaseous species,including H2O,CO2,CO,CH4 and HCOOH,were identified and monitored,in which HCOOH was detected for the first time.The results indicated that ascorbic acid began to decompose at 191℃.Its decomposition process consisted of three stages,and dehydration and decarboxylation to form furfural were the possible principal mechanism.The kinetic analysis for the first decomposition stage was also carried out by the isoconversional method and the master plots method.The results indicated that this process can be described by the model of 1st order reaction.