马氏珍珠贝来源DPP-IV抑制活性肽的虚拟筛选及其作用机制

为了快速发现马氏珍珠贝来源二肽基肽酶IV（dipeptidyl peptidase IV,DPP-IV）抑制活性肽,本研究利用数据库中20个已报道的DPP-IV抑制肽组成训练集,构建了药效团模型并通过测试集分子和Fisher随机验证法对模型进行了评估。利用在线网站PeptideCutter,以珍珠贝肉蛋白为原料,进行虚拟酶解。使用最优药效团模型（Hypo1）对虚拟酶解获得的192个低分子肽（氨基酸数小于或等于5）进行初步筛选,接着以分子对接的方法进一步筛选,并且对潜在的DPP-IV抑制活性肽进行固相合成,体外验证其活性并分析其作用机制。结果表明,药效团结合分子对接技术筛选了4个理论上可能具有高活性的DPP-IV抑制肽,即LPIY、VQDR、PIY和APSL。其中,VQDR、PIY没有表现出抑制活性,而LPIY和APSL具有较高的DPP-IV抑制活性,其IC₅₀值分别为521.19 和258.67 μmol/L。与DPP-IV相互作用的机理表明,肽LPIY和APSL与DPP-IV活性口袋中的氨基酸残基形成了多个氢键,且N-端第二个位置的脯氨酸（P）也均与活性口袋中的残基形成了Pi-Alkyl作用,因此促进了LPIY和APSL的DPP-IV抑制作用。本研究为高效筛选珍珠贝来源的DPP-IV抑制肽提供了理论方法。     

时频电磁(TFEM)技术：数据联合约束反演

在油气勘探中,时频电磁（TFEM）数据反演可以利用更多的已知资料。充分利用已知资料有效减小反演非唯一性具有重要意义。建立联合反演目标函数,采用人工鱼群算法实现TFEM勘探水平电场和垂直磁场的联合约束反演;设计层厚度、电阻率和极化率等参数三类模型空间,以实现对不同层位参数的灵活约束,给出了模型参数空间设置的方法和规则,能够充分利用或多或少的已知资料对反演参数进行约束;同时提出了三类模型的分步反演方案,其中一些措施有效地减小了反演结果的非唯一性、提高了反演精度。模型测试和实际剖面反演表明,人工鱼群算法和分步约束的反演方案能够很好地克服反演的非唯一性并确保勘探精度和效果,有较强的实用性。     

智能自愈合凝胶研究进展及在钻井液领域的应用前景

自愈合凝胶是一类受损后能自行愈合形成接近整体凝胶强度的智能材料。通过系统介绍基于疏水、氢键和静电作用的物理自愈合凝胶和基于亚胺键、酰腙键和Diels-Alder反应的动态化学键作用的化学自愈合凝胶的研究进展,结合钻井液应用实践以及不同类型自愈合凝胶材料自身特性,总结了自愈合凝胶材料在钻井液防漏、堵漏、固壁和降滤失领域的应用前景。自愈合凝胶材料可作为随钻防漏和堵漏剂,进入井下高渗基质和裂缝后聚集堆积,自行愈合形成整体高强度凝胶封堵漏失通道;作为固壁材料可通过氢键、静电和黏滞作用吸附聚集在井筒壁面,愈合后形成高强度凝胶固壁层,封堵孔隙和微裂缝,强化井壁稳定性;作为降滤失材料可与黏土、聚合物协同作用,愈合后在井壁形成一层致密的高强度滤饼,降低钻井液滤失量。自愈合凝胶材料在钻井液领域的研究和应用将促进钻井液技术的智能化。     

Observation and simulation of wind waves near a typical reef lagoon in South China Sea

Due to the inference of the uneven shallow water seabed and the surrounding islands,the wind-generated waves around or in a reef lagoon are rather complicated,and critical to the safety of floating structures deployed near islands or inside a lagoon.This paper aims to find a feasible analysis tool for the wave simulations near islands and reefs.The proposed three methods of grid techniques of WAVEWATCH III(WW3)are assessed by using on-site measured data which was collected and accumulated for about 5 years since August 2014 by a wave observation system deployed inside and outside a reef lagoon in South China Sea.In the assessments,the wave statistics including the correlation coefficients,root mean square errors,and their variances are used to quantify the precisions of the simulation results of the significant wave heights,mean wave periods,and peak wave directions at two sites.Among the three methods,the Multi-scale Zone and Multi-scale grid Technique(MZMGT)established on unstructured triangular grids exhibits better results in terms of the accuracy and CPU cost.In addition,the bimodal feature of wave spectra was observed at both sites of the reef lagoon in different typhoon events.The wave characteristics inside the reef lagoon and open sea are also analyzed.     

人工红树林碳通量变化特征及其影响因素分析

红树林是重要的滨海蓝碳生态系统.人工红树林在恢复过程中碳交换过程受到气候、植被等环境的影响,与成熟红树林呈现较大差异.本研究采用闭路涡动相关系统对珠江河口人工红树林湿地生态系统进行二氧化碳(CO₂)通量和甲烷(CH₄)通量的观测,并基于通径分析方法探讨了环境要素对总初级生产力(GPP)、生态系统呼吸(R_e)、CO₂和CH₄通量的影响.结果表明：CO₂通量呈现明显的日变化特征,受到GPP和R_e的协同影响,其季节变化特征不明显;CH₄通量则呈现明显的季节变化特征.2019—2020年CO₂年通量为74.9～138.4 g·m^-2·a^-1(以C计,下同),CH₄年通量为25.1～25.9 g·m^-2·a^-1.CO₂变化特征受到GPP的直接影响,总辐射(R_a<...     

A linear yield surface in plastic cyclic analysis

A three-parameter, uniaxial symmetric, linear yield surface suitable for tension-weak, as well as equal tension and compression yield stress material, is presented. This yield condition, along with a linear kinematic hardening rule and an associated flow rule, is used to formulate the constitutive laws for sides and comers of the yield surface. The formulation is based on incremental plasticity with the assumption of small displacements and suitable for plane stress problems, under monotonie or cyclic loading. Finite element formulation, numerical solution, and applications are discussed.     

Influences of different modifiers on the disintegration of improved granite residual soil under wet and dry cyclesOA

The disintegration of granite residual soil is especially affected by variations in physical and chemical properties. Serious geologic hazards or engineering problems are closely related to the disintegration of granite residual soil in certain areas. Research on the mechanical properties and controlling mechanisms of disintegration has become a hot issue in practical engineering. In this paper, the disintegration characteristics of improved granite residual soil are studied by using a wet and d...     

后弯管模型多环节能量转换特性实验研究

后弯管（BBDB）技术从波浪能到电能的转换要经过多个环节,为提高后弯管技术能量转换性能,对一种新型的后弯管技术多环节阻尼形式展开了实验研究。水槽实验研究表明,在气流单向做功条件下,规则波下俘获宽度比（CWR）峰值为113.7%,随机波下CWR峰值为81.9%,而在气流双向做功时,规则波下CWR峰值为138.6%,随机波下CWR峰值为94.0%;相对于简单气孔阻尼模型,带有导叶、叶轮和发电机元件阻尼的试验模型的CWR稍高于简单纯气孔模型,两者CWR曲线变化的趋势接近。     

Investigation of structural,optical, and electrochemical properties of niobium-doped Li4Ti5O12 for high-performance aqueous capacitor electrode

In this study, nanocrystalline niobium-doped lithium titanate Li₄Ti₅O₁₂ (LTO) was successfully synthesized with various stoichiometric ratios (x = 0, 0.025, 0.05, 0.075, 0.1) using a niobium ethoxide precursor via the solid-state synthesis method. X-ray diffraction spectroscopy results revealed that the synthesized samples possess a spinel structure without any impurities, and lattice constants expanded from 8.357 Å to 8.363 Å as the concentration of niobium ions increased. Scanning electron microscopy (SEM) analysis demonstrated that particle sizes ranged from 1.13 to 1.56 μm. The smallest particle size was observed in the LTO-Nb-0.075 sample. The maximum absorptions were detected in the ultraviolet region, and the band gaps of Nb-doped Li₄Ti_5-xNb_xO₁₂ (x = 0, 0.025, 0.05, 0.075, 0.1) were determined using Tauc plots. These results showed that the band gaps of Nb-doped LTO were lowered compared to pure LTO, suggesting enhanced electron conductivity. X-ray photoelectron spectroscopy (XPS) measurements confirmed that the band gaps of Nb-doped samples decreased as the formation of oxygen vacancies and Ti³⁺ ions increased due to Nb⁵⁺ substitution. All synthesized samples displayed well-defined redox peaks in pairs during the cyclic voltammetry (CV) measurement. The optimal stoichiometric ratio for doping lithium titanate was found to be x = 0.075, as it yielded the highest specific capacitance of 3.59 F/g and the lowered band gap value of 3.13 eV. Therefore, this study provides further encouragement for applying LTO electrodes in aqueous capacitors and electrical uses.     

低功耗海上仪器回收通信信标的研制

可靠的回收系统是海洋仪器进行有效观测和获取数据的关键一环,其中仪器在海面上与科考船之间的通信信标是回收系统中的重要组成部分.该文设计的低功耗海上仪器回收通信信标是一套可用于海洋仪器回收的轻量化信标机——集成了全球定位系统(GPS)定位模块和Lora低功耗远距离通信模块,浮出海面后可自动切换为待机模式.该系统在低功耗待机...