Interpretation of capillary pressure curves using invasion percolation theory

Invasion percolation was studied on three-dimensional regular lattices of various node numbers. A new model has been developed to obtain the pore-size distribution from capillary pressure measurements. The new model is superior to the conventional percolation model, since it takes into account the physical trapping of the wetting phase. The irreducible wetting phase saturation includes the film of the wall of the pores, the dead-end pore volume, and the main contribution by pores isolated from the outlet of the medium by the nonwetting phase. This has been related to the node number and the sample 3dimensions. Over 100 capillary pressure curves of consolidated media have been collected. Good agreement was obtained between this data set out and our invasion percolation predictions using node numbers of 6–13, as reported by Mishra and Sharma. The pore-throat size distribution function estimated by our new model is broader than from the conventional percolation and the capillary tube models.Nomenclature c constant - D pore throat diameter [m] - D _max maximum pore diameter [m] - f(D) correlation function of pore throat size and pore body size - L a parameter representing the dimension of a sample - n node number - p pressure [N/m²] - S _n the nonwetting phase saturation - x random number ranging from 0 to 1.0 - X ^a X _t ^a /X/ _t - X _e ^a X _t ^a –X _t ⁱ - X ⁱ X _t ⁱ /X _t ^a - X _nw fraction of pore volume occupied by the injected phase - X _t fraction of pores larger thanD - X _t ^a total accessibility of pores larger thanD - X _t ⁱ total isolation of pores larger thanD - contact angle - interfacial tension [N/m] - (D) pore throat size distribution     

Comparative Study of a Series of 99mTc(CO)3 Mannosylated Dextran Derivatives for Sentinel Lymph Node Detection

Sentinel lymph node detection (SLND) is rapidly entering common practice in the management of patients with tumors. The introduction of mannose molecules to ^99mTc-labeled dextrans, so far, showed that the sentinel node could trap these agents due to their recognition by the mannose receptors of lymph node macrophages. The current study aimed to synthesize, characterize, and biologically evaluate a series of mannosylated dextran derivatives labeled with ^99mTc for potential use in SLND. The compounds were designed to have a dextran with a molecular weight of 10–500 kDa as a backbone, S-derivatized cysteines, efficient SNO chelators, and mannose moieties for binding to mannose receptors. They were successfully synthesized, thoroughly characterized using NMR techniques, and labeled with the fac-[^99mTc(CO)₃]⁺ synthon. Labeling with high yields and radiochemical purities was achieved with all derivatives. In vivo biodistribution and imaging studies demonstrated high uptake in the first lymph node and low uptakes in the following node and confirmed the ability to visualize the SLN. Among the compounds studied, ^99mTc-D75CM demonstrated the most attractive biological features, and in combination with the high radiochemical yield and stability of the compound, its further evaluation as a new radiopharmaceutical for sentinel lymph node detection was justified.     

Structure of node polynomials for curves on surfaces

We provide a structural generalization of a theorem by Kleiman–Piene, concerning the enumerative geometry of nodal curves in a complete linear system on a smooth projective surface S. Provided that r, the number of nodes, is sufficiently small compared to the ampleness of the linear system, we show that, under certain assumptions, the number of r‐nodal curves passing through points in general position on S is given by a Bell polynomial in universally defined integers which we identify, using classical intersection theory, as linear, integral polynomials evaluated in four basic Chern numbers. Furthermore, we provide a decomposition of the as a sum of three terms with distinct geometric interpretations, and discuss the relationship between these polynomials and Kazarian's Thom polynomials for multisingularities of maps.     

Exploiting perturbed and coalescent anchor node geometry with semidefinite relaxation for sensor network localization

Localization in wireless sensor networks (WSNs) suffer from performance issues whenever the anchor nodes (which are aware of their location) are subjected to motion from their usual position. Moreover, accurate localization demands more anchor nodes which is a scarce resource and needs to be used judiciously. In the current work, we propose a novel framework that addresses these two prime concerns by harnessing the inter relationship of anchor node geometry. For an unknown source node surrounded by anchor nodes, the anchors lying on the inner boundary of the deployment geometry may be carrying closely related information about source node, leading to redundancy and inefficient utilization. By anticipating the level of correlation between these anchors, localization can be made more frugal. Rigorous mathematical analysis is carried out to derive lower bounds on estimated locations. Based on fisher information from two proposed models, a convex estimation objective function is formulated using semidefinite programming (SDP) approach to validate the theoretical proceedings. Based on the findings, the proposed method is able to successfully extract useful information about the unknown source node location with limited number of anchor nodes, hence achieving superior localization.     

MR-DWI成像预测乳腺癌腋窝淋巴转移的价值

本研究探讨磁共振弥散加权成像(MR-DWI)评估乳腺癌患者腋窝淋巴结转移的价值。回顾性选取乳腺癌患者68例(观察组),同时选取乳腺良性病变患者60例作为对照组,比较两组MR-DWI差异。观察组弥漫高信号、混杂高信号比例明显高于对照组(P<0.05);观察组病灶ADC值明显低于对照组(P<0.05);观察组Ⅲ期病灶ADC值明显低于Ⅰ~Ⅱ期(P<0.05);观察组腋窝淋巴结转移ADC值明显低于无淋巴结转移(P<0.05);弥漫高信号和其他信号组织ADC值比较差异无统计学意义(P>0.05);ADC值预测腋窝淋巴结转移的ROC曲线下面积为0.752,P<0.05。MR-DWI在乳腺癌腋窝淋巴结转移诊断应用价值较好,值得临床使用。     

爆炸冲击震动对砖墙破坏作用的数值模拟

砖墙在爆炸冲击震动作用下的动力反应非常复杂,本构关系很难精确建立。本文阐述了砖墙几种常用的有限元模拟方法,分析各种方法的优缺点,确定采用一种砖块和砂浆分开的精细化建模的三维砖墙有限元模型;通过LS-DYNA软件,得到砖墙在水平爆炸冲击震动荷载下的破坏过程,计算结果与实验现象很好。研究表明：该种分析模型综合考虑了砖块和砂浆之间复杂的相互作用,并且对砂浆层进行了单独建模,保证了砖墙在数值模拟上的真实性和正确性,因此可以准确地模拟出实验中砖块之间砂浆层的损伤积累破坏。

     

A RECTANGULAR SHELL ELEMENT FORMULATION WITH A NEW MULTI-RESOLUTION ANALYSIS

A multi-resolution rectangular shell element with membrane-bending based on the Kirchhoff-Love theory is proposed. The multi-resolution analysis （MRA） framework is formulated out of a mutually nesting displacement subspace sequence, whose basis functions are constructed of scaling and shifting on the element domain of basic node shape functions. The basic node shape functions are constructed from shifting to other three quadrants around a specific node of a basic element in one quadrant and joining the corresponding node shape functions of four elements at the specific node. The MRA endows the proposed element with the resolution level （RL） to adjust the element node number, thus modulating structural analysis accuracy accordingly. The node shape functions of Kronecker delta property make the treatment of element boundary condition quite convenient and enable the stiffness matrix and the loading column vectors of the proposed element to be automatically acquired through quadraturing around nodes in RL adjusting. As a result, the traditional 4-node rectangular shell element is a mono-resolution one and also a special case of the proposed element. The accuracy of a structural analysis is actually determined by the RL, not by the mesh. The simplicity and clarity of node shape function formulation with the Kronecker delta property, and the rational MRA enable the proposed element method to be implemented more rationally, easily and efficiently than the conventional mono-resolution rectangular shell element method or other corresponding MRA methods.