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Age-hardening behavior,corrosion mechanisms,and passive film structure of nanocrystalline Al-V supersaturated solid solution

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Journal of Materials Science & Technology 2023年第4期135卷 1-12页

作者： J.Christudasjustus M.r.Felde C.S.Witharamage J.Esquivel A.A.Darwish C.Winkler r.k.gupta Department of Materials Science and Engineering North Carolina State UniversityRaleighNC 27606United States Department of Chemical Biomolecular and Corrosion EngineeringThe University of AkronAkronOH 44325United States

The effect of age-hardening on microstructure,hardness,and corrosion of an Al-5at.%V alloy,produced us-ing high-energy ball milling and subsequent cold compaction,has been *** alloy exhibited a grain size below 100 nm and extremely high solid solubility of V in Al(3.1 at.%).The age-hardening was carried out at 150,200,and 250℃.The peak-aged condition of 150℃ demonstrated the highest hardness-transpired from grain refinement,precipitation,and solid solution *** corrosion re-sistance of the Al-5at.%V alloy was studied as a function of aging *** peak-aged condition retained the corrosion resistance while it deteriorated in the over-aged ***,the cor-rosion resistance of the ball-milled Al alloys in all the aging conditions was superior to that of pure *** passive film structure and origin of corrosion were studied using scanning/transmission electron mi-croscopy(S/TEM).The high corrosion resistance of the alloy was attributed to the V enrichment at the film/metal interface and deposition of V on the cathodic phases,which suppresses the dissolution of Al within the pit and therefore promotes repassivation in the early stages of corrosion.

关键词： Al alloys Nanocrystalline alloy Age-hardening Ball milling Corrosion Hardness

Enhanced corrosion resistance of phytic acid coated magnesium by stearic acid treatment

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Transactions of Nonferrous Metals Society of China 2013年第5期23卷 1237-1244页

作者： r.k.gupta k.MENSAH-DArkWA J.SANkAr D.kUMAr Engineering research Center for revolutionizing Metallic Biomaterials(ErC-rMB) North Carolina A&T State University

A green chemical conversion coating for magnesium was obtained with a phytic acid solution. The microstructure and corrosion properties of phytic acid conversion coated magnesium were further improved by soaking in stearic acid solution. The phytic acid conversion coated magnesium after soaking in the stearic acid showed no micro-cracks and the surface became very smooth. The corrosion behavior of the uncoated and coated magnesium samples was studied by electrochemical methods. The corrosion resistance of the stearic acid treated sample was much higher than that of phytic acid conversion coated magnesium or uncoated magnesium. The electrochemical results indicated that the stearic acid treated coating provided effective corrosion protection to the magnesium sample.

关键词： magnesium phytic acid stearic acid corrosion impedance spectroscopy

Pitting corrosion behavior and corrosion protection performance of cold sprayed double layered noble barrier coating on magnesium-based alloy in chloride containing solutions

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Journal of Magnesium and Alloys 2023年第9期11卷 3099-3119页

作者： M.Daroonparvar A.Helmer A.M.ralls M.U.Farooq khan A.k.kasar r.k.gupta M.Misra S.Shao P.L.Menezes N.Shamsaei National Center for Additive Manufacturing Excellence Auburn UniversityAuburnAL 36849USA Department of Mechanical Engineering Auburn UniversityAuburnAL 36849USA Department of Materials Science and Engineering College of EngineeringNorth Carolina State University911 Partners WayRaleighNC 27695USA Department of Mechanical Engineering University of Nevada RenoRenoNV 89501USA Department of Nuclear Engineering and radiological Sciences University of MichiganAnn ArborMI 48105 USA Department of Chemical and Materials Engineering University of Nevada RenoNV 89501USA

Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride containing solutions. In this research, commercially pure α-Ti top coating having good pitting potential(~1293 mV_(SCE)), high microhardness(HV_(0.025): 263.03) and low wear rate was applied on a CP-Al coated Mg-based alloy using high pressure cold spray technology. Potentiodynamic polarization(PDP) curves indicated that the probability of transition from metastable pits to the stable pits for cold spayed(CS) Al coating is considerably higher compared to that with the CS Ti top coating(for Ti/Al/Mg system). In addition, CS Ti top coating was in the passivation region in most pH ranges even after 48 h immersion in 3.5 wt% NaCl solution. The stored energy in the CS Ti top coating(as a passive metal) was presumed to be responsible for the easy passivation. Immersion tests indicated no obvious pits formation on the intact CS Ti top coating surface and revealed effective corrosion protection performance of the CS double layered noble barrier coatings on Mg alloys in 3.5 wt% NaCl solution even after 264 h.

关键词： Ti coating Mg alloys Localized corrosion Passivity Dislocation density Crystallite size

Immunogenicity and reactogenicity of a recombinant hepatitis B vaccine in subjects over age of forty years and response of a booster dose among nonresponders

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World Journal of Gastroenterology 2003年第5期9卷 1132-1134页

作者： kunal Das r.k.gupta V.kumar P.kar Department of Medicine Maulana Azad Medical College & L.N.HospitalNew Delhi.Medical AdvisorPanacea Biotec Co.New Delhi

AIM:The study was initiated to evaluate the reactogenicity and immunogenicity of a recombinant hepatitis B vaccine in age group >40 years and to study the response of a single booster dose in primary non-responders to the hepatitis B vaccination. METHODS:A total of 102 volunteers without markers of hepatitis B infection (negative for HBsAg,anti-HBc antibody, HBeAg and anti-HBs antibody) received 20μg of recombinant HB vaccine intramuscularly at 0,1,and 6 *** HBs titers were evaluated by a quantitative Elisa kit at 90 and 210 days.A booster dose of 20μg HB vaccine was given after 6 months of the 3^(rd) vaccine dose to the 15 non- responders and anti-HBs titers were measured after i month. rESULTS:Seroprotection (anti-HBs GMT^3 10 IU/L) was achieved in 85.3 % (87/102) *** mean GMT titers of the vaccine responders was 136.1 IU/*** the seroprotected individuals,there were 32.4% (33/102) hyporesponders (anti- HBs titers re responders (anti-HBs titers >100 IU/L).All the non-responders (15/15) responded to a single dose of the booster dose of recombinant HB vaccine and their mean anti-HBs antibody titers were more than 100.5 mIU/ml after the booster dose. CONCLUSION:recombinant hepatitis B vaccine offers good seroprotection in the age group >40 years and has a good safety profile.A single booster dose after 6 months in primary non-responders leads to good seroprotective anti-HBs antibody ***,larger population based studies are needed to evaluate the role of a booster dose in selected group of non-responders and whether such an approach will be cost effective.

关键词： Adult Age Factors Aged Female Hepatitis B Antibodies Hepatitis B Vaccines dosage Humans Immunization, Secondary Male Middle Aged Safety Vaccines, Synthetic

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取向聚合物的结晶动力学(下)

国外纺织技术（化纤．染整．环境保护分册） 1990年第2期 5-9页

作者： r.k.gupta 邵惠丽

结果和讨论在180至240℃范围,每相隔10℃,做一熔纺实验。图3所示是炉长为0.7米、温度为220℃时,在三个不同的卷绕速度下,实验得到的纤维温度分布,最大的卷绕速度为1500米/分。从图中可以看出,在炉子内部,纤维的温度基本保持在常数。而... 详细信息

结果和讨论在180至240℃范围,每相隔10℃,做一熔纺实验。图3所示是炉长为0.7米、温度为220℃时,在三个不同的卷绕速度下,实验得到的纤维温度分布,最大的卷绕速度为1500米/分。从图中可以看出,在炉子内部,纤维的温度基本保持在常数。而一离开炉子,便迅速降到玻璃化温度以下。

关键词：取向聚合纤维结晶动力学聚合理论

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蔗糖酯和蔗糖酯-甘油酯乳化剂

日用化学品科学 1984年第1期 1-6页

作者： r.k.gupta 顾季寅

为某一体系选择合适的乳化剂常需进行大量实验。Griffin等根据亲水-亲油平衡(HLB)的原理提出了选择适宜乳化剂的方法。新乳化剂的HLB值是通过其乳化性质与已知HLB值表面活性剂的乳化性质相比较测得。低HLB值(3～6)的表面活性剂是油包水... 详细信息

为某一体系选择合适的乳化剂常需进行大量实验。Griffin等根据亲水-亲油平衡(HLB)的原理提出了选择适宜乳化剂的方法。新乳化剂的HLB值是通过其乳化性质与已知HLB值表面活性剂的乳化性质相比较测得。低HLB值(3～6)的表面活性剂是油包水型乳化剂,中HLB值(8～13)是水包油型乳化剂,高HLB值

关键词： HLB 仁油大豆油校正曲线食用油农药助剂乳化剂多元醇甘油甲乙酮脂肪族酮丁酮水数法去溶剂气相色谱气液色谱油椰子蔗糖酯脂酸

Covalent Bond Based Android Malware Detection Using Permission and System Call Pairs

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Computers, Materials & Continua 2024年第3期78卷 4283-4301页

作者： rahul gupta kapil Sharma r.k.Garg Department of Information Technology Delhi Technological UniversityNew Delhi110042India Department of Mechanical Engineering Deenbandhu Chhotu Ram University of Science and TechnologyMurthal131039India

The prevalence of smartphones is deeply embedded in modern society,impacting various aspects of our *** versatility and functionalities have fundamentally changed how we communicate,work,seek entertainment,and access *** the many smartphones available,those operating on the Android platform dominate,being the most widely used *** widespread adoption of the Android OS has significantly contributed to increased malware attacks targeting the Android ecosystem in recent ***,there is an urgent need to develop new methods for detecting Android *** literature contains numerous works related to Android malware *** far as our understanding extends,we are the first ones to identify dangerous combinations of permissions and system calls to uncover malicious behavior in Android *** introduce a novel methodology that pairs permissions and system calls to distinguish between benign and malicious *** approach combines the advantages of static and dynamic analysis,offering a more comprehensive understanding of an application’s *** establish covalent bonds between permissions and system calls to assess their combined *** introduce a novel technique to determine these pairs’Covalent Bond Strength *** pair is assigned two scores,one for malicious behavior and another for benign *** scores serve as the basis for classifying applications as benign or *** correlating permissions with system calls,the study enables a detailed examination of how an app utilizes its requested permissions,aiding in differentiating legitimate and potentially harmful *** comprehensive analysis provides a robust framework for Android malware detection,marking a significant contribution to the *** results of our experiments demonstrate a remarkable overall accuracy of 97.5%,surpassing various state-of-the-art detection techniques proposed in the current literature.

关键词： Android malware android security hybrid analysis permission and system call pairs

Direct scaling of residual displacements for bilinear and pinching oscillators

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 129-149页

作者： Mohammad Saifullah Vinay k.gupta Department of Civil Engineering Indian Institute of Technology KanpurKanpur 208016India

The estimation of residual displacements in a structure due to an anticipated earthquake event has increasingly become an important component of performance-based earthquake engineering because controlling these displacements plays an important role in ensuring cost-feasible or cost-effective repairs in a damaged structure after the *** attempt is made in this study to obtain statistical estimates of constant-ductility residual displacement spectra for bilinear and pinching oscillators with 5%initial damping,directly in terms of easily available seismological,site,and model *** of the available models for the bilinear and pinching oscillators are useful when design spectra for a seismic hazard at a site are not *** statistical estimates of a residual displacement spectrum are proposed in terms of earthquake magnitude,epicentral distance,site geology parameter,and three model parameters for a given set of ductility demand and a hysteretic energy capacity coefficient in the case of bilinear and pinching models,as well as for a given set of pinching parameters for displacement and strength at the breakpoint in the case of pinching model *** proposed scaling model is applicable to horizontal ground motions in the western *** earthquake magnitudes less than 7 or epicentral distances greater than 20 km.

关键词： residual displacement spectrum bilinear hysteresis model pinching hysteresis model nonlinear analysis scaling model

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聚合物提高采收率技术的现场实施

国外油田工程 1998年第9期14卷 5-5,19页

作者： Mahendra Pratap r.P.roy r.k.gupta 王卫星河南油田科技处

本文介绍了印度Sanand油田采用聚合物驱技术提高采收率的具体做法，详细阐明了聚合物驱机理，在广泛的室内试验的基础上，筛选出了适合于Sanand油田的聚合物类型和最佳浓度。通过先进的先导性试验、先导性扩大试验，最后转入油田规模应... 详细信息

本文介绍了印度Sanand油田采用聚合物驱技术提高采收率的具体做法，详细阐明了聚合物驱机理，在广泛的室内试验的基础上，筛选出了适合于Sanand油田的聚合物类型和最佳浓度。通过先进的先导性试验、先导性扩大试验，最后转入油田规模应用的方法。保证了聚合物驱的经济性。应得结果表明，采收率水平大大提高，增产效果非常明显。

关键词：聚合物驱油提高采收率现场实施油田