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Label-free colorimetric estimation of proteins using nanoparticles of silver

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Nano-Micro Letters 2010年第3期2卷 164-168页

作者： siddhartha Shrivastava Debabrata Dash Department of Biochemistry Institute of Medical SciencesBanaras Hindu University

Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance(SPR) *** nanoparticles have been employed for the development of SPR-based colorimetric *** the present report we have described a sensitive colorimetric approach for estimation of proteins,within a detection limit of 10?80 μg/m L,using unmodified silver *** the common advantages of colorimetric assay such as simplicity,high sensitivity,and low cost,our method has a label-free design and provides an important and attractive alternative to classical sensing probes and *** present work will contribute to the development of nanotechnology-based diagnostic tools.

关键词： Silver nanoparticles Agglutination Surface plasmon resonance Colorimetric estimation Bovine serum albumin Immunoglobulin

Optimization by Estimation of Distribution with DEUM Framework Based on Markov Random Fields

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International Journal of Automation and computing 2007年第3期4卷 262-272页

作者： siddhartha Shakya John McCall Intelligent Systems Research Center British Telicom Adastral ParkIpswich IP5 3REUK School of Computing The Robert Gordon University Aberdeen AB25 1HGUK

This paper presents a Markov random field （MRP） approach to estimating and sampling the probability distribution in populations of solutions. The approach is used to define a class of algorithms under the general heading distribution estimation using Markov random fields （DEUM）. DEUM is a subclass of estimation of distribution algorithms （EDAs） where interaction between solution variables is represented as an undirected graph and the joint probability of a solution is factorized as a Gibbs distribution derived from the structure of the graph. The focus of this paper will be on describing the three main characteristics of DEUM framework, which distinguishes it from the traditional EDA. They are： 1） use of MRF models, 2） fitness modeling approach to estimating the parameter of the model and 3） Monte Carlo approach to sampling from the model.

关键词： Estimation of distribution algorithms evolutionary algorithms fitness modeling Markov random fields Gibbs distri-bution.

Constraint Preserving Schemes Using Potential-Based Fluxes *** Transport Equations

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Communications in Computational Physics 2011年第3期9卷 688-710页

作者： siddhartha Mishra Eitan Tadmor Centre of Mathematics for Applications(CMA) University of OsloP.O.Box 1053BlindernN-0316 OsloNorway Center of Scientific Computation and Mathematical Modeling(CSCAMM) and Department of Mathematicsand Institute for Physical Sciences and Technology(IPST)University of MarylandMD 20742-4015USA

We consider constraint preserving multidimensional evolution equations.A prototypical example is provided by the magnetic induction equation of plasma *** constraint of interest is the divergence of the magnetic *** design finite volume schemes which approximate these equations in a stable manner and preserve a discrete version of the *** schemes are based on reformulating standard edge centered finite volume fluxes in terms of vertex centered *** potential-based approach provides a general framework for faithful discretizations of constraint transport and we apply it to both divergence preserving as well as curl preserving *** present benchmark numerical tests which confirm that our potential-based schemes achieve high resolution,while being constraint preserving.

关键词： Multidimensional evolution equations magnetohydrodynamics finite-difference finite volume schemes constraint transport potential-based schemes

Prognostic Role of Preoperative Tricuspid Annular Plane Systolic Excursion (TAPSE) in Mitral Valve Replacement (MVR) for Rheumatic Mitral Stenosis Patients

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World Journal of Cardiovascular Surgery 2024年第8期14卷 115-130页

作者： Satyajit Sharma Muhit Abdullah Md. Noor-E-Elahi Mozumder Munjerin Refat Synthee Md. Zafar-Al-Nimari Anowarul Azim Saikat Das Gupta Dewan Iftakher Raza Chowdhury siddhartha Shankar Howlader Noel Crypian Gomes Saleh Ahmed Samir Kumar Biswas Department of Cardiac Surgery National Heart Foundation Hospital & Research Institute (NHFH & RI) Dhaka Bangladesh Department of Cardiac Surgery National Institute of Cardiovascular Diseases & Hospital Dhaka Bangladesh Department of Cardiothoracic and Vascular Surgery Square Hospital Dhaka Bangladesh Department of Cardiothoracic and Vascular Surgery Evercare Hospital Chattogram Bangladesh

Tricuspid annular plane systolic excursion has been proposed as a simple and reproducible parameter for quantitative assessment of the right ventricular ejection fraction. The prognostic importance of preoperative TAPSE in patients with mitral valve replacement for rheumatic mitral stenosis patients is still under focused. Therefore, the objective of the study was to predict the outcome after MVR in rheumatic mitral stenosis patients in relation to preoperative TAPSE. This comparative cross-sectional study was conducted at the Department of Cardiac Surgery, National Heart Foundation Hospital and Research Institute. A total of 72 patients of rheumatic mitral stenosis patients who underwent mitral valve replacement were included in the study. They were divided into two groups: Group A and B. Group A included 36 patients with TAPSE 0.05) except for the preoperative TAPSE. Mean TAPSE of Group A was 13.17 (±1.40) and Group B was 18.61 (±1.57), the difference was statistically significant (p 0.05). Among the postoperative complications, including postoperative atrial fibrillation was higher in Group A (30.56%) than Group B (11.11%), mean ventilation time was higher in Group A (27.78%) than Group B (5.56%), length of intensive care was higher in Group A (33.33%) than Group B (11.12%), and hospital stay was higher in Group A (25.0%) than Group B (5.56%), (p < 0.05). Higher preoperative TASPE could be used as a prognostic tool for MVR in rheumatic mitral stenosis patients in our settings.

关键词： Tricuspid Annular Plane Systolic Excursion Mitral Valve Replacement Rheumatic Heart Disease Mitral Stenosis Right Ventricular Ejection Fraction Postoperative Complications

KINETIC FUNCTIONS IN MAGNETOHYDRODYNAMICS WITH RESISTIVITY AND HALL EFFECT

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Acta Mathematica Scientia 2009年第6期29卷 1684-1702页

作者： Philippe G. Le siddhartha Mishra FlochLaboratoire Jacques-Louis Lions Centre National de la Recherche ScientifiqueUniversit Pierre et Marie Curie (Paris 6) 4 Place Jussieu 75258 Paris France Seminar for Applied Mathematics D-Math ETH HG Raemistrasse Zürich-8092 Switzerland

We consider a nonlinear hyperbolic system of two conservation laws which arises in ideal magnetohydrodynamics and includes second-order terms accounting for magnetic resistivity and Hall effect. We show that the initial value problem for this model may lead to solutions exhibiting complex wave structures, including undercompressive nonclassical shock waves. We investigate numerically the subtle competition that takes place between the hyperbolic, diffusive, and dispersive parts of the system. Following Abeyratne, Knowles, LeFloch, and Truskinovsky, who studied similar questions arising in fluid and solid flows, we determine the associated kinetic function which characterizes the dynamics of undereompressive shocks driven by resistivity and Hall effect. To this end, we design a new class of ＂schemes with eontroled dissipation＂, following recent work by LeFloch and Mohammadian. It is now recognized that the equivalent equation associated with a scheme provides a guideline to design schemes that capture physically relevant, nonclassical shocks. We propose a new class of schemes based on high-order entropy conservative, finite differences for the hyperbolic flux, and high-order central differences for the resistivity and Hall terms. These schemes are tested for several regimes of （co-planar or not） initial data and parameter values, and allow us to analyze the properties of nonclassical shocks and establish the existence of monotone kinetic functions in magnetohydrodynamics.

关键词： hyperbolic conservation law magnetohydrodynamics magnetic resistivity Hall effect undercompressive shock kinetic function

Atomistic modeling and rational design of optothermal tweezers for targeted applications

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Nano Research 2021年第1期14卷 295-303页

作者： Hongru Ding Pavana siddhartha Kollipara Linhan Lin Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA

Optical manipulation of micro/nanoscale objects is of importance in life sciences,colloidal science,and *** tweezers exhibit superior manipulation capability at low optical ***,our implicit understanding of the working mechanism has limited the further applications and innovations of optothermal ***,we present an atomistic view of opto-thermo-electro-mechanic coupling in optothermal tweezers,which enables us to rationally design the tweezers for optimum performance in targeted ***,we have revealed that the non-uniform temperature distribution induces water polarization and charge separation,which creates the thermoelectric field dominating the optothermal *** further design experiments to systematically verify our atomistic *** by our new model,we develop new types of optothermal tweezers of high performance using low-concentrated ***,we demonstrate the use of new tweezers in opto-thermophoretic separation of colloidal particles of the same size based on the difference in their surface charge,which has been challenging for conventional optical *** the atomistic understanding that enables the performance optimization and function expansion,optothermal tweezers will further their impacts.

关键词： optothermal tweezers optical tweezers optical manipulation thermophoresis molecular dynamics simulation

Ammonium persulphate promoted synthesis of polyethylene glycol entrapped potassium tribromide and its application in acylation and bromination of some selective organic compounds

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Chinese Chemical Letters 2013年第10期24卷 866-868页

作者： Rupa Rani Dey siddhartha Sankar Dhar Department of Chemistry National Institute of Technology

In this study, a new method of synthesis of polyethylene glycol supported potassium tribromide （PEG KBr3） and its application in acylation and bromination reactions are reported. Ammonium persulphate oxidizes I（Br to the corresponding tribromide which is entrapped by polyethylene glycol leading to stable PEG KBr3. The reagent is proved to be highly efficient for the acylation of variety of alcohols and bromination of activated aromatic substrates. The method is a mild, one pot reaction and involves no use of toxic reagents.

关键词： Potassium bromide Polyethylene glycol (PEG) Ammonium per sulphate Acylation Bromination

α-Fe2O3 immobilized benzimidazolium tribromide as novel magnetically retrievable catalyst for one-pot synthesis of highly functionalized piperidines

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Chinese Chemical Letters 2016年第11期27卷 1725-1730页

作者： Bappi Paul Sethumathavan Vadivel siddhartha Sankar Dhar Department of Chemistry National Institute of Technology Silchar Silchar-788010 Assam India Department of Chemistry PSC College of Technology Peelamedu Coimbatore-641004 Tamilnadu India

Nanostructured ot-Fe2O3 were prepared by precipitation followed by calcination method. Cetyltrimethylammonium bromide （CRAB） was used as surfactant. The nano α-Fe2O3 was then silanized with （3-chloropropyl）-triethoxysilane （CPTES） by room temperature mixing ofα-Fe2O3 and CPTES to produce silane coated ct-Fe2O3 （CIPr-Si@Fe2O3）. As-synthesized CIPr-Si@Fe2O3 was functionalized via covalent grafting of benzimidazole to produce 3-（1-benzimidazole）Pr-Si@Fe2O3. This was further reacted with bromine to afford α-Fe2O3 immobilized benzimidazolium tribromide （α-Fe2O3-BIM tribromide）. This ionic liquid （IL） α-Fe2O3 BIM tribromide was characterized by FT-IR, XRD, TEM, SEM, TGA, VSM, EDX and BET analysis. The as-synthesized IL tribromide was used as catalyst for one-pot synthesis of highly substituted piperidines. The method is greener in terms of solvent selection, recovery of the catalyst and efficiency.

关键词： Nano α-Fe2O3 Covalent grafting Ionic liquid Multicomponent reaction

Optical Patterning of Two-Dimensional Materials

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Research 2020年第1期2020卷 1064-1078页

作者： Pavana siddhartha Kollipara Jingang Li Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA

Recent advances in the field of two-dimensional(2D)materials have led to new electronic and photonic devices enabled by their unique properties at atomic *** 2D materials into desired patterns on substrates is often an essential and foremost step for the optimum performance of the functional *** this regard,optical patterning of 2D materials has received enormous interest due to its advantages of high-throughput,site-specific,and on-demand *** years have witnessed scientific reports of a variety of optical techniques applicable to patterning 2D *** this minireview,we present the state-of-the-art optical patterning of 2D materials,including laser thinning,doping,phase transition,oxidation,and *** applications based on optically patterned 2D materials will be discussed as *** further developments,optical patterning is expected to hold the key in pushing the frontiers of manufacturing and applications of 2D materials.

关键词： frontier doping optimum