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Measurement of bit-rock interface temperature and wear rate of the tungsten carbide drill bit during rotary drilling

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Friction 2020年第6期8卷 1073-1082页

作者： Vijay kumar shankar Bijay Mihir KUNAR Chivukula Suryanarayana MURTHY M R RAMESH Department of Mining Engineering National Institute of Technology KarnatakaSurathkal 575025India Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkal 575025India

Rock drilling is an essential operation in mining *** at the bit-rock interface plays a major role in the wear rate of the drill *** paper primarily focuses on the wear rate of tungsten carbide(WC)drill bit and the interrelationship between temperature and wear rate during rotary drilling operations conducted using a computer numerical control(CNC)*** interrelationship between the temperature and wear rate was studied with regard to three types of rock samples,i.e.,fine-grained sandstone(FG)of uniaxial compressive strength(UCS)that is 17.83 MPa,medium-grained sandstone(MG)of UCS that is 13.70 MPa,and fine-grained sandstone pink(FGP)of UCS that is 51.67 *** rate of the drill bit has been measured using controlled parameters,i.e.,drill bit diameter(6,8,10,12,and 16 mm),spindle speed(250,300,350,400,and 450 rpm),and penetration rate(2,4,6,8,and 10 mm/min),***,a fully instrumented laboratory drilling set-up was *** weight of each bit was measured after the bit reached 30 mm depth in each type of the rock ***,effects of the bit-rock interface temperature and operational parameters on wear rate of the drill bits were *** results show that the wear rate of drill bits increased with an increase in temperature for all the bit-rock combinations *** is due to the silica content of the rock sample,which leads to an increase in the frictional heat between the bit-rock ***,in case of medium-grained sandstone,the weight percentage(wt%)of SiO2 is around 7.23 wt%,which presents a very low wear rate coefficient of 6.33×10^–2 mg/(N?m).Moreover,the temperature rise during drilling is also minimum,i.e.,around 74℃,in comparison to that of fine-grained sandstone and fine-grained sandstone *** addition,this paper develops the relationship between temperature and wear rate characteristics by employing simple linear regression analysis.

关键词： temperature wear rate drilling simple linear regression

Structural build-up model for three-dimensional concrete printing based on kinetics theory

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 998-1014页

作者： Prabhat Ranjan PREM P.S.AMBILY shankar kumar Greeshma GIRIDHAR Dengwu JIAO Advanced Materials Laboratory CSIR-Structural Engineering Research CentreChennai 600113India Department of Architecture and Civil Engineering City University of Hong KongHong Kong 999077China

The thixotropic structural build-up is crucial in extrusion-based three-dimensional(3D)concrete *** paper uses a theoretical model to predict the evolution of static and dynamic yield stress for printed *** model employs a structural kinetics framework to create a time-independent constitutive link between shear stress and shear *** model considers flocculation,deflocculation,and chemical hydration to anticipate structural *** reversible and irreversible contributions that occur throughout the build-up,breakdown,and hydration are defined based on the proposed structural ***,detailed parametric studies are conducted to evaluate the impact of model *** is revealed that the proposed model is in good agreement with the experimental results,and it effectively characterizes the structural build-up of 3D printable concrete.

关键词： structural build-up rheology thixotropy 3D printable concrete kinetics theory ultra high performance concrete

Analysis of docosanol using GC/MS:Method development,validation,and application to ex vivo human skin permeation studies

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Journal of Pharmaceutical Analysis 2022年第2期12卷 287-292页

作者： Vijay kumar shankar Mei Wang Srinivas Ajjarapu Praveen Kolimi Bharathi Avula Reena Murthy Ikhlas Khan Sathyanarayana Narasimha Murthy Department of Pharmaceutics and Drug Delivery University of MississippiOxfordMS38677USA Natural Products Utilization Research Unit Agricultural Research ServiceU.S.Department of AgricultureOxfordMS38677USA National Center for Natural Products Research Research Institute of Pharmaceutical SciencesSchool of PharmacyUniversity of MississippiOxfordMS38677USA Topical Products Testing LLC OxfordMS38677USA

Docosanol is the only US Food and Drug Administration(FDA)approved over-the-counter topical product for treating recurrent oral-facial herpes simplex *** analytical methods for docosanol are required to demonstrate the bioequivalence of docosanol topical products.A gas chromatography/selected ion monitoring mode mass spectrometry(GC/SIM-MS)method was developed and validated for docosanol determination in biological *** and isopropyl palmitate(internal standard)were separated on a high-polarity GC capillary column with(88%cyanopropy)aryl-polysiloxane employed as the stationary *** ions of m/z 83 and 256 were selected to monitor docosanol and isopropyl palmitate,respectively;the total run time was 20 *** GC/SIM-MS method was validated in accordance with US FDA guidelines,and the results met the US FDA acceptance *** docosanol calibration standards were linear in the 100-10000 ng/mL concentration range(R^(2)>0.994).The recoveries for docosanol from the receptor fluid and skin homogenates were>93.2%and>95.8%,*** validated method was successfully applied to analyze ex vivo human cadaver skin permeation *** applying Abreva®cream tube and Abreva®cream pump,the amount of docosanol that penetrated human cadaver skin at 48 h was 21.5±7.01 and 24.0±6.95 ng/mg,***,we concluded that the validated GC/SIM-MS was sensitive,specific,and suitable for quantifying docosanol as a quality control *** method can be used for routine analysis as a costeffective alternative to other techniques.

关键词： Docosanol Fatty alcohols Gas chromatography-mass spectrometry Topical formulation Skin permeation

Influence of Benzoate on Substituent Benzoic Acids with Implications on Spectroscopic Studies through Inter Molecular Hydrogen Bonding

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Materials Sciences and Applications 2011年第6期2卷 503-508页

作者： Ravi shankar kumar 不详

Comprehensive study on the homologous series of compounds in the form A-R- HHB are synthesized with central rigid core as benzoic acids together with substituent’s alkoxy (A) and alkyl (R) group of equal chain lengths from 5 to 10 are connected to hexyl-p-hydroxy benzoate (HHB). These complexes form supramolecular structures by self assembling process due to intermolecular hydrogen bonding. The formation is analyzed with techniques involving polarizing optical microscope, infrared spectroscopy, proton NMR spectroscopy and powdered X-ray diffraction. Results suggest that complexes arise from both A and R groups exhibit enantiotropic layered texture of crystal G phase observed by microscopic studies due to flexible nature of mesogenics. The conversion of free to molecular complexes is determined with variations in spectral shifts between its terminal groups COOH and OH of molecules involving inter molecular hydrogen bonding and its bonding index by FTIR spectra. The changes in structure and dynamics due to hydrogen bonding in complexes are convinced by proton NMR spectra with chemical shifts in specified range. The defects in crystal structure responsible for enantiotropic phenomena are analyzed by powdered X ray diffraction.

关键词： Phase Transitions Microscopy IR Spectra and Hydrogen Bonding

Why do young people with chronic kidney disease die early?

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World Journal of Nephrology 2014年第4期3卷 143-155页

作者： shankar kumar Richard Bogle Debasish Banerjee Medical School St George’sUniversity of London Department of Cardiology St George’s Hospital NHS Trust Department of Cardiology Epsom and St Helier University HospitalsNHS Trust Renal and Transplantation Unit St George’s Hospital NHS Trust

Cardiovascular disease poses the greatest risk of premature death seen among patients with chronic kidney disease(CKD).Up to 50% of mortality risk in the dialysis population is attributable to cardiovascular disease and the largest relative excess mortality is observed in younger *** early CKD,occlusive thrombotic coronary disease is common,but those who survive to reach end-stage renal failure requiring dialysis are more prone to sudden death attributable mostly to sudden arrhythmic events and heart failure related to left ventricular hypertrophy,coronary vascular calcification and electrolyte *** this review,we discuss the basis of the interaction of traditional risk factors for cardiovascular disease with various pathological processes such as endothelial dysfunction,oxidative stress,low grade chronic inflammation,neurohormonal changes and vascular calcification and stiffness which account for the structural and functional cardiac changes that predispose to excess morbidity and mortality in young people with CKD.

关键词： Chronic kidney disease Cardiovascular mortality Cardiorenal syndrome Endothelial dysfunction Vascular calcification and stiffness

Unravelling the situation of malaria misdiagnosis in India:Its adverse impact and management strategies

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Asian Pacific Journal of Tropical Medicine 2022年第7期15卷 290-292页

作者： Gaurav kumar Hari shankar ICMR-National Institute of Malaria Research Sector-8DwarkaDelhiIndia Indian Council of Medical Research New DelhiIndia

Malaria is a public health problem in several parts of India.A continuous decrease in malaria has been reported in India,from about 2.0 million cases in 2000 to about 0.2 million in 2020[1].In February 2016,the Government of India formally launched the National Framework for Malaria Elimination,which outlines the strategies for eliminating malaria from India by 2030[2].It aims to interrupt indigenous malaria transmission(zero indigenous case reporting)throughout the country,prevent the re-establishment of transmission in areas where it has been eliminated,and maintain national malaria-free status by 2030 and beyond,using the existing intervention tools and *** 2017,India launched its five-year National Strategic Plan for Malaria Elimination,which is mainly district focused rather than the National Framework for Malaria Elimination,which was state focused[3].India has shown a 71%reduction of malaria cases in 2019 compared to 2015,which was achieved by strengthening surveillance,improving diagnosis and treatment,and intensive vector control measures using existing *** India,Odisha state contributed 37.4%of total malaria cases in 2015,which was reduced to 12%in 2019 using the Durgama Anchalare Malaria Nirakaran initiative and comprehensive case management of malaria[4].

关键词： malaria Malaria India

Failure investigation on high velocity impact deformation of boron carbide(B_(4)C) reinforced fiber metal laminates of titanium/glass fiber reinforced polymer

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Defence Technology（防务技术） 2022年第6期18卷 963-975页

作者： S.Suresh kumar P.A.shankar K.Lalith kumar Department of Mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringKalavakkamChennai603110India

High velocity ballistic impact deformation behaviour of Titanium/GFRP Fiber Metal Laminates(FML)has been *** single and multiple projectiles impact conditions were ***/GFRP FML targets were fabricated with addition of 5%and 10%weight percentage of boron carbide(B_(4)C)*** properties of Ti/GFRP FML targets were determined as per ASTM *** velocity ballistic experiments were conducted using Armour Piercing Projectile(APP)of diameter 7.62 mm and velocity ranging between 350 and 450 m/*** of penetration of the projectile into the target was *** deformation behaviour of Ti/GFRP targets with and without the presence of ceramic powder(B_(4)C)was investigated.“Ductile hole growth”failure mode was observed for pure GFRP target when subjected to single projectile impact whereas“plugging”failure mode was noted for Ti/GFRP *** presence of B_(4)C(5%by weight)particles has significantly improved the ballistic resistance of the Ti/GFRP FML target by offering frictional resistance to the projectile *** addition(10%by weight)of B_(4)C has reduced the ballistic performance due to *** of the targets showed‘brittle cracking’or‘fragmentation’*** compared to the published results of Aluminium(Al 1100/GFRP and Al 6061/GFRP)FMLs,Ti/GFRP FML showed lesser DoP which increases its potential application to aerospace industry.

关键词： Ti/GFRP FML Ballistic impact Armour piercing projectile Boron carbide Depth of penetration Plugging

Entire onion source-derived redox porous carbon electrodes towards efficient quasi-solid-state solar charged hybrid supercapacitor

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Journal of Materials Science & Technology 2022年第30期125卷 118-127页

作者： Edugulla Girija shankar Amit kumar Das Jae Su Yu Department of Electronics and Information Convergence Engineering Institute for Wearable Convergence ElectronicsKyung Hee UniversityGyeonggi-do 17104Republic of Korea

Biomass-derived electrodes inherently containing redox-active species have gained extensive attention recently due to their availability,eco-friendliness,sustainability,and low *** report novel binder-free faradic surface redox onion-derived carbon positive electrode with nano regime particles by hydrothermal synthesis and Na^(+)and Cl^(−)ions diffused porous carbon negative electrode via a carbonization ***-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of oxidized sulfur and(N-6)pyridinic N-based redox groups inherently present in the as-prepared *** electrochemical analysis of the positive electrode revealed its faradic redox type of energy storage mechanism with an excellent specific capacitance of 1805 Fg^(-1) at the current density of 3 Ag^(-1) as well as appreciable long-term cycling stability(76.8%retention after 10000 charge-discharge cycles).Meanwhile,the negative electrode exhibited a maximum specific capacitance of 373 Fg^(-1) at 1 Ag^(-1) with outstanding long-term cycling stability(100.7%retention after 10000 cycles).The fabricated polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state hybrid supercapacitor(QHSC)delivered excellent energy density and power density of 19.94 Wh kg^(-1) and 374.99 W kg^(-1),respectively with an ultralong cyclic life(102.3% retention)over 10000 ***,the QHSC was connected to a solar panel to store renewable *** charged QHSC effectively powered a speedometer,enlightening its potential application in advanced sustainable energy storage systems.

关键词： Binder-free Biomass Green source Hybrid supercapacitor Solar energy storage Faradic redox type

Dynamics of some new solutions to the coupled DSW equations traveling horizontally on the seabed

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Journal of Ocean Engineering and Science 2024年第2期9卷 154-163页

作者： Raj kumar Ravi shankar Verma Department of Mathematics Faculty of Engineering&TechnologyVeer Bahadur Singh Purvanchal UniversityJaunpur 222003India

The system of(1+1)-coupled Drinfel’d-Sokolov-Wilson equations describes the surface gravity waves travelling horizontally on the *** objective of the present research is to construct a new variety of analytical solutions for the *** invariants are derived with the aid of Killing form by using the optimal algebra classification via Lie symmetry *** invariant solutions involve time,space variables,and arbitrary *** adequate constraints on arbitrary constants,solutions are represented graphically to make them more applicable in designing sea *** behavior of solutions shows asymptotic,bell-shaped,bright and dark soliton,bright soliton,parabolic,bright and kink,kink,and periodic *** constructed results are novel as the reported results[26,28,29,30,33,38,42,49]can be deduced from the results derived in this *** remaining solutions derived in this study,are absolutely different from the earlier *** this study,the physical character of analytical solutions of the system could aid coastal engineers in creating models of beaches and ports.

关键词： Coupled Drinfel’d-Sokolov-Wilson model Invariants Killing form Optimal sub algebra Lie symmetry reductions