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Radio frequency“sutureless”fistulotomy-a new way of treating fistula in anus

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World journal of Gastroenterology 2003年第5期9卷 1082-1085页

作者： Pravin j.gupta gupta Nursing Home D/9LaxminagarNAGPUR-440022India

AIM: To explore the effect of the classical lay open technique or fistulotomy with the radio frequency surgical device in the treatment of fistula in ***: In our study, the conventional 'lay open'technique, or 'fistulotomy' was performed by employing the radio frequency surgical device as an alternative to the traditional knife and scissors. In a span of 18 months starting from july 1999 to December 2000, 210 cases with fistula in anus of varied types were operated in our nursing home exclusively applying the radio frequency ***: The results of the study were not only encouraging but also were satisfactory. A follow up of the operated patients with radio frequency surgery over a period of 15 months, i.e. from December 2000 to March 2002 was summarized as below: (a) average time taken by the patient to resume routine - 7 days; (b) none of the patient had any interference with the continence; (c) the wounds were found healed within an average time of 47 days; (d) delayed wound healing was noticed only in 7 patients; (e) recurrence/failure rate was reduced to as low as 1.5 ***: This technique has been found superior to the conventional fistulotomy in the sense that the time taken for the whole procedure is reduced to almost half, chances of bleeding are reduced to a minimum and the use of suture material is dispensed with. The procedure can safely be called a "Sutureless fistulotomy".

关键词：射频治疗术瘘管切开术肛瘘外科治疗安全性手术方法

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处理CO2/CFC的温室气体

地理译报 1995年第2期14卷 41-49页

作者： j.B.Weenink j.gupta L.H.j.M janssen 李胜强

温室气体ＣＯ２和ＣＦＣ已受到全世界的重视。而本文重点论述的是那睦并未受到同等关注的温室气体。文章试图系统地提出一个框架结构，以保证在此框架内的全球，地区和国家级政策的制定。

关键词：气候变化温室气体二氧化碳 CFC

Corrosion Behavior and Hardness of Al-M (M:Mo,Si,Ti,Cr) Alloys

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 333-341页

作者： j.Esquivel R.K.gupta Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325-3906 USA

The corrosion behavior of Al-5 at.% Cr, A1-5 at.% Si, Al-5 at.% Mo and Al-5 at.% Ti produced via casting and Al-5 at.% Cr produced by high-energy ball milling and subsequent consolidation by cold pressing was studied using potentiodynamic polarization and surface analysis following constant immersion tests. Alloys were characterized using a scanning electron microscope coupled with the energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. Hardness, a representative of the strength, was also measured. The alloys produced by casting contained coarse intermetallics and therefore exhibited poor corrosion resistance. Al-5 at.% Cr alloy produced by high-energy ball milling exhibited a significantly improved corrosion resistance and hardness, which was attributed to the grain refinement to nanoscale and extended solid solubility of Cr in AL The study indicated that the high-energy ball milling was capable of producing Al alloys with improved corrosion behavior and hardness.

关键词： Corrosion Mechanical alloying Casting Aluminum alloys

Instability of binary nanofluids with magnetic field

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Applied Mathematics and Mechanics(English Edition) 2015年第6期36卷 693-706页

作者： U.gupta j.SHARMA V.SHARMA Dr.S.S.Bhatnagar University Institute of Chemical Engineering and Technology Panjab University Energy Research Centre Panjab University Department of Mathematics Himachal Pradesh University

The present paper investigates the effects of a vertical magnetic field on the double diffusive nanofluid convection, The effects of the Brownian motion and ther- mophoresis due to the presence of nanoparticles and the effects of the Dufour and Sorer parameters due to the presence of solute are included in the investigated model. The normal mode technique is used to solve the conservation equations. For the analytical study, valid approximations are made in the complex expression for the Rayleigh number to get useful and interesting results. The bottom heavy binary nanofluids are more stable than the regular binary fluids, while the top heavy binary nanofluids are less stable than the regular binary fluids. The critical wave number and the critical Rayleigh number in- crease whereas the frequency of oscillation （for the bottom heavy configuration） decreases when the Chandrasekhar number increases. The numerical results for the alumina-water nanofiuid are studied by use of the MATHEMATICA software.

关键词： natural convection binary nanofluid Brownian motion thermophoresis,Chandrasekhar number

Evaluation of graphite depressants in a poly-metallic sulfide flotation circuit

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International journal of Mining Science and Technology 2017年第2期27卷 285-292页

作者： Nikhil gupta Department of Mining and Minerals Engineering Virginia Polytechnic Institute and State UniversityBlacksburgVA 24061USA

Synthetic dyes are commonly used for graphite depression in poly-metallic flotation circuits; however,these dyes can be very expensive. The aim of this study is to evaluate performance of certain low-cost alternative depressants for a complex lead-zinc(Pb-Zn) ore rich in graphite(Gr-C) on a conventional mini pilot-scale flotation circuit. The reagents used were commercial and industrial grade starch; agro-based waste-sugarcane bagasse and charred(burnt) bagasse powder. The primary evaluation criteria were quality(grades) of lead and zinc concentrates, their recoveries(%), and graphite rejection(%) in the *** tests using nigrosine as graphite depressant showed 94.3% rejection of Gr-C. The results with commercial starch were found as effective with 93.8% graphite rejection. Furthermore, bagasse powder showed potential in improving product quality(36.4% and 65.6% Pb grade and recovery) with an intermediate effectiveness in graphite rejection(85.6%). The order of effectiveness in Gr-C rejection follows nigrosine % commercial starch > bagasse > industrial starch > charred bagasse. In addition, the effect these depressants on silver(byproduct) grade and recovery was also investigated.

关键词： Graphite depressants Sulfide flotation Dyes Starch Bagasse Hydrophobic impurities

Investigation of strong shock wave interactions with CeO2 ceramic

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journal of Advanced Ceramics 2014年第4期3卷 297-305页

作者： Vishakantaiah jAYARAM Asha gupta K.P.j.REDDY Shock Induced Materials Chemistry Lab SSCUIndian Institute of ScienceBangalore-560012India Texas Materials Institute the University of Texas at AustinAustinTexas 78712USA Department of Aerospace Engineering Indian Institute of ScienceBangalore-560012India

Strong shock wave interactions with ceramic material ceria(CeO_(2))in presence of O_(2)and N2 gases were investigated using free piston driven shock tube(FPST).FPST is used to heat the test gas to very high temperature of about 6800-7700 K(estimated)at pressure of about 6.8-7.2 MPa for short duration(2-4 ms)behind the reflected shock *** is subjected to super heating and cooling at the rate of about 106 K/*** of CeO_(2)sample was done before and after exposure to shock heated test gases(O_(2)and N2).The surface composition,crystal structure,electronic structure and surface morphology of CeO_(2)ceramic were examined using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),Fourier transform infrared(FTIR)spectrometry,scanning electron microscopy(SEM)and high resolution transmission electron microscopy(HRTEM).Results obtained from the experimental investigations show that CeO_(2)can withstand high pressure accompanied by thermal shock without changing its crystal *** CeO_(2)releases lattice oxygen making it possible to shift between reduced and oxidized states upon the interaction with shock heated *** to such reaction mechanism,CeO_(2)ceramic undergoes nitrogen doping with decrease in lattice *** reveal that CeO_(2)retains its crystal structure during strong shock interaction,even at elevated pressure.

关键词： shock tube shock interaction high enthalpy gas ceria nitrogen-doped surface reaction

Beneficiation of coal using supercritical water and carbon dioxide extraction:sulfur removal

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International journal of Coal Science & Technology 2021年第4期8卷 717-726页

作者： Matthew j.DeCuir Ram B.gupta Bhima Sastri Department of Chemical and Life Science Engineering Virginia Commonwealth UniversityRichmondVA 23284-3068USA Office of Fossil Energy U.S.Department of Energy19901 Germantown RoadGermantownMD 20874-1290USA

This work explores the use of carbon dioxide,water,and their mixtures as solvent for the precombustion beneficiation of raw coal without using any toxic mineral acids in the temperature range of 200-400℃.The fluid polarity,ionic constant,and supercritical point can be adjusted by H_(2)O/CO_(2)ratio and *** carbon dioxide to hydrothermal fluid also increases the ionization by forming carbonic *** with supercritical fluids have several benefits including enhanced mass transport,ease of separation and recycle,wide range of extractive capability and tunability,better inherent safety,and in the case of carbon dioxide and water-low cost.A semi-continuous extraction system was designed and built in which pressure,temperature and the relative flow rates of CO_(2)and H_(2)O can be *** powder is kept in a packed bed and the extraction is carried out at 143 bar *** sulfur as a model heteroatom,extractive efficiency is examined as a function of the temperature,fluid composition,fluid flow,and extraction *** results indicate that carbon dioxide,water,and supercritical water-carbon dioxide(ScWC)all can effectively extract about 50%of total sulfur from bituminous coal in 1 *** above 350℃decreased effectiveness,and extraction above the supercritical point of pure water caused hydrothermal *** extraction may provide necessary control to prevent organic dissolution while removing sulfur.

关键词： Coal Supercritical Sulfur Beneficiation Cleaning Extraction

Influence of Various Parameters on Collapse Behaviour of Thin Cylinders

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上海交通大学学报 2004年第z2期38卷 1-7页

作者： N K gupta Applied Mechanics Department ⅡT Delhi India - 110016

Axial compression experiments on as received aluminum tubes and tubes with wall thickness eccentricity incorporated by off centre machining showed that the eccentricity caused transition of their collapse mode from axisymmetric to diamond. The numerical simulation of the collapse phenomenon was undertaken using a static non-linear Finite Element Analysis in ANSYS, and results are found to compare well with the experimental load compression and energy absorption responses for axisymmetric concertina and non-axisymmetric diamond modes. Having validated the numerical model with experiments, it has been used to undertake a systematic study of the load - compression characteristics and collapse mode transitions of the tubes with varying eccentricities in wall thickness and boundary conditions, as well as the material properties.

关键词： thin tube collapse thickness eccentricity ANSYS axial compression

Determining the relationship between chemical composition and size, shape and effective density of airborne fine particles through concurrent use of inertial and optical based measurements

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Particuology 2016年第5期14卷 93-101页

作者： Anand Kumar Tarun gupta Environmental Engineering and Management Program Indian Institute of Technology Kanpur Kanpur 208016 India Institute of Atmospheric and Climate Science Swiss Federal Institute of Technology Zurich Zurich 8092 Switzerland Department of Civil Engineering Indian Institute of Technology Kanpur Kanpur 208016 India

This study presents the development of a medium flow, multiple slit based PM2.5 （particle aerodynamic diameter 〈2.5 μm） inertial impactor. Its performance was compared with that of a light scattering based optical particle sizer in a field study and in controlled lab based experiments using polydisperse dolomite powder as test aerosol. The impactor＇s optimum nozzle configuration had a cutoff size of 2.51 μm （aero- dynamic diameter） at an operating flow rate of 215 L/rain with a pressure drop of 0.35 kPa across the impactor stage. Because the apparent particle density of an ambient aerosol depends on the physical properties and the chemical composition of the particles, the PM2.5 mass concentration was measured with an optical particle sizer and an inertial impactor over a weekday and a weekend day in a field study during which the effective particle shape factor and density were in tandem modified in order to com- pare the results from the two sampling techniques. The correlation of the two instrument results tended towards 1：1 with increasing values of shape factor （irregular shaped） and effective particle density. This observation was supported through chemical investigations of the collected mass, which showed a higher percentage contribution from elements which are mostly of crustal nature （namely, Ca, Fe, and Mg）.

关键词： lmpactor PM2.5 Optical particle counter Effective particle density Shape factor