高纯度藻胆蛋白的分离纯化研究进展

藻胆蛋白在食品、化妆品等领域中具有广泛的应用前景,同时也可以作为医学研究中的荧光标记物和氧化应激疾病的潜在治疗药物。高纯度藻胆蛋白的分离纯化一直是国内外的研究热点。目前,蓝藻中的螺旋藻和红藻中的微藻紫球藻是研究较多的材料,龙须菜近年来的广泛种植,扩大了原材料的来源。藻胆蛋白的粗提主要是由物理破碎和化学沉淀组成,破碎的方法因原料的不同而具有一定的差异。高纯度的藻胆蛋白获取主要是通过离子交换,疏水层析等方法,这些方法耗时长,回收率低;双水相萃取,利凡诺沉淀,壳聚糖和活性碳吸附沉淀为人们分离纯化藻胆蛋白提供了新的思路。     

高压喷射注浆防渗加固若干问题探讨

高压喷射注浆作为一种将水力采煤与静压注浆相结合诞生的注浆形式,已成功应用于地质灾害治理、水库大坝及垃圾渗滤液防渗加固等工程中,取得了显著的社会经济效益。从高压喷射流的特性、高压喷射注浆机理、高压喷射注浆形成防渗固结体的影响因素及其防渗性能、高压喷射注浆对地层切割搅拌范围的影响因素、高压喷射注浆对浆材的要求,以及高压喷射注浆常见事故及对策6个方面对高压喷射注浆防渗加固进行了较为全面的探讨,提出了将包括SJP注浆材料、仿生非光滑技术等在内的新技术应用到高喷注浆防渗加固中解决目前存在问题的新思路,是一种有意义的尝试,同时也是切实可行的。     

抗高温随钻封堵材料研究进展

钻遇渗透性漏失地层、破碎地层及低承压地层时,通常加入随钻封堵材料以防止钻井液漏失、提高孔壁稳定性和地层承压能力。深井高温地层及高温地热、高温干热岩钻探,遇到上述复杂情况时,需采用抗高温封堵材料。本文介绍了我国近年来抗高温随钻封堵材料研究与应用的进展情况,包括由桥接堵漏材料组成的抗高温随钻堵漏剂、膨胀型聚合物堵漏剂、超低渗透处理剂及弹性石墨等新型抗高温随钻堵漏材料。分析了4种抗高温随钻封堵材料的组分及其堵漏原理,并对抗高温随钻封堵材料的研究方向提出了建议。     

Characterization of clastic rock using a biconcave bond model of DEM

This paper presents a biconcave bond model to investigate the effect of the cementation between grains on the mechanical behavior of rock. The proposed model considers the shape of the bonds among particles that have a biconcave cement form, based on observations of microscopic rock images. The general equations of the proposed model are based on Dvorkin theory. The accuracy and efficiency of the bond model is improved in three ways. After the biconcave bond model is implemented in the discrete element method software Particle Flow Code in 2 Dimensions, a series of numerical uniaxial compression tests were performed to investigate the relationships between the micro‐ to macro‐parameters. The simulations revealed that the biconcave bond model reflects the effect of micro‐parameters, such as the elastic modulus and Poisson's ratio of the cement, on the macroscopic deformation of cemented granular material. Variations in the bond geometry caused extremely diverse macro‐mechanical behaviors. Experimental results concerning rock demonstrate that the biconcave bond model accurately captures the mechanical behavior of intact rock and supports an innovative method for investigating the relationships between the micro‐ and macro‐parameters of cemented granular material. Copyright © 2016 John Wiley & Sons, Ltd.     

3-D numerical models of viscous flow applied to fold nappes and the Rawil depression in the Helvetic nappe system (western Switzerland)

The Helvetic nappe system exhibits three-dimensional (3-D) features such as the lateral variation in geometry between the Morcles and Doldenhorn fold nappes or the Rawil depression. We perform 3-D finite element simulations of linear and power-law viscous flow to investigate fold nappe formation during shortening of a half graben with laterally varying thickness. 3-D ellipsoids and corresponding 2-D intersection ellipses are used to quantify finite strain. Fold nappes which formed above a thicker graben have (i) larger amplitudes, (ii) a less sheared and thinned overturned limb, and (iii) a larger thickness than fold nappes formed above a thinner graben. These results agree with observations for the Morcles and Doldenhorn nappes. We also perform 3-D simulations for a tectonic scenario suggested for the evolution of the Rawil depression. The basement is shortened and extended laterally and includes a graben which is oblique to the shortening direction and acts as mechanical weak zone. The graben causes laterally varying basement uplift generating a depression whose amplitude depends on the graben orientation and the stress exponent of basement and sediments. The axial plunge of the depression is smaller (approximately 10°) than the observed plunge (approximately 30°) indicating that additional processes are required to explain the geometry of the Rawil depression.     

Modelling of membranes in the material point method with applications

The objective of this paper is to formulate and validate an accurate MPM approach for the numerical simulation of the large displacement of membranes containing soil. In the proposed approach, the membrane is discretised by a surface mesh that allows accurate simulation of membrane stresses. The membrane is free to move through a three‐dimensional grid for a continuum consisting of tetrahedral elements. The approach is applied to model a geocontainer being released from a split barge, taking into account the frictional contact between the geotextile and the barge. No‐slip contact is assumed between the geotextile and the soil inside. The effect of geocontainer interaction is investigated by dropping a second container. Copyright © 2014 John Wiley & Sons, Ltd.     

An improved implicit numerical integration of a non‐associated,three‐invariant cap plasticity model with mixed isotropic–kinematic hardening for geomaterials

The Sandia GeoModel is a continuum elastoplastic constitutive model that captures many features of the mechanical response for geological materials over a wide range of porosities and strain rates. Among the specific features incorporated into the formulation are a smooth compression cap, isotropic/kinematic hardening, nonlinear pressure dependence, strength differential effect, and rate sensitivity. This study attempts to provide enhancements regarding computational tractability, domain of applicability, and robustness of the model. A new functional form is presented for the yield and plastic potential functions. This reformulation renders a more accurate, robust, and efficient model as it eliminates spurious solutions attributed to the original form. In addition, we achieve a high‐performance implementation, because the local iterative method is allowed to recast residual vectors with a uniform dimensionality. The model is also furnished with a smooth, elliptical tension cap to account for the tensile yielding. Moreover, an efficient algorithm is introduced, which decreases the computational cost by differentiating the updated shear yield surface from the cap surface based on the trial relative stress state. Finally, various numerical examples including a large‐scale boundary value problem are presented to demonstrate the fidelity of the modified model and to analyze its numerical performance. Copyright © 2015 John Wiley & Sons, Ltd.     

散体材料桩复合地基沉降计算方法的研究

对散体材料桩复合地基桩与桩间土的相互作用进行研究,试验表明：散体材料桩在一定深度内发生鼓胀破坏,因此,将复合地基分为鼓胀段、非鼓胀段和下卧层3段进行沉降计算。假定桩-土协调变形,利用弹性力学空间问题理论推导出散体材料桩复合地基的沉降计算公式,为按沉降控制的复合地基优化设计提供计算依据。算例分析表明,所提方法的计算结果与实测值基本吻合。     

泡沫轻质材料试验研究的均匀设计方法及配方优化

泡沫轻质材料是一种用于岩土工程的新型材料。采用均匀试验设计方法进行材料的配方试验,运用多元非线性回归方法进行方差分析,分析了试验因素的主效应和因素间的交互效应,并建立有约束的非线性规划问题,采用最优化方法进行寻优计算,得出满足工程要求的最优配比。     

剪切带图案的复杂性及应力-应变曲线的离散性

在平面应变压缩条件下,通过在岩样左边界靠近下端面的位置及右边界的不同位置预制材料缺陷,采用拉格朗日元法研究了材料缺陷位置不同时的剪切带图案启动、演变及试样的宏观力学行为。在数值计算中,采用了莫尔-库仑与拉破坏复合的破坏准则,峰后岩石的本构关系为线性应变软化。当试样左、右边界上的缺陷距离较远时,剪切带仅出现1条,以通过两缺陷形式贯通试样两边界;当两缺陷距离较近时,启动于缺陷附近的剪切带按各自其固有方向发展,剪切带图案十分复杂。当右缺陷距离试样上端面较近时,由于上端面的约束,仅位于缺陷下方的剪切带能得到充分的发展。若剪切带数量较少且贯通试样两边界时,试样发生脆性剪切破坏,应力-变形曲线软化段比较陡峭;反之,发生韧性剪切破坏,软化段比较平缓。当剪切带的前端迎面遇到试样上、下端面附近的上、下三角形区域时,由于端面的约束,剪切带的方向将改变。当剪切带的前端与试样的纵向对称线距离较近时,剪切带发生折射现象;当距离较远时,剪切带将发生反射现象。