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Production and characterisation of new bioresorbable radiopaque mg–Zn–Y alloy to improve X-ray visibility of polymeric scaffolds

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Journal of magnesium and Alloys 2022年第6期10卷 1694-1703页

作者： alok srivastava Naresh Bhatnagar mechanical Engineering Department Indian Institute of TechnologyDelhiIndia

For the medical diagnosis,radiopaque materials(Rm)made from high specific gravity elements like Pt,Au,Ta,Iodine,Bromine are either attached or blended or coated on an implant to makes it detectable under X-ray/Fluoroscopy/*** facilitate the surgeon in an operation theatre to position an implant during the ***,Rm are non-degradable,thus in case of biodegradable implants,it may detach from the body and accumulate in vital organ cause serious health ***,a new bioresorbable radiopaque material(BRm)was produced by alloying the high specific gravity elements Zn(35%w/w)and Y(4%w/w)with mg *** this alloy,three main phases were identified,alpha mg,mg_(7)Zn_(3)and icosahedral quasicrystalline I-phase mg3Zn6Y,which reinforce the mg ***,BRm was powdered to a size of less than 25 microns and blended in different ratios with bioresorbable poly-L-lactic acid(PLLA)for fabricating PLLA/BRm *** microparticles were uniformly distributed and interfacial bonded with the *** X-ray was passed through bio-composite to captureμCT radiograph for evaluating linear attenuation co-efficient(μ)and optical density(OD).Thermal analysis reveals that BRm particles act as a nucleating site and enhance the crystallinity of the polymeric *** the In Vitro accelerated degradation study,the alkaline nature of BRm neutralise the acidity of PLLA and balance the pH of the body fluid to reduce the inflammatory reactions,but this compromises the stability of the polymer as it increases the decomposition rate.

关键词： magnesium alloys X-ray Quasicrystal Polymer matrix composites Radiopacity

Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal

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Acta Oceanologica Sinica 2019年第5期38卷 32-50页

作者： Dwivedi Suneet mishra alok Kumar srivastava Atul K Banerjee Centre of Atmospheric and Ocean Studies and m N Saha Centre of Space Studies University of Allahabad

In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean(10°S–25°N,45°–100°E) covering the Arabian Sea(AS) and Bay of Bengal(BoB). The model run using the open boundary conditions is carried out at 10 km horizontal resolution and highest vertical resolution of 2 m in the upper *** surface and sub-surface structure of hydrographic variables(temperature and salinity) and currents is compared against the observations during 1998–2014(17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The highresolution model's ability in correct estimation of the spatio-temporal mixed layer depth(mLD) variability of the AS and BoB is also shown. The lowest mLD values are observed during spring(march-April-may) and highest during winter(December-January-February) seasons. The maximum mLD in the AS(BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum mLD in these regions during march-April-may becomes as low as 11–12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the mLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents.

关键词： Indian Ocean modeling Arabian Sea and Bay of Bengal mixed layer depth transport

Thermal decomposition and kinetics of plastic bonded explosives based on mixture of HmX and TATB with polymer matrices

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Defence Technology（防务技术） 2017年第1期13卷 22-32页

作者： Arjun Singh Tirupati C.Sharma mahesh Kumar Jaspreet Kaur Narang Prateek Kishore alok srivastava Terminal Ballistics Research Laboratory Defence Research&Development OrganisationMinistry of DefenceExplosive DivisionSector 30Chandigarh(UT)160030India Department of Chemistry&Centre for Advanced Studies in Chemistry Panjab UniversityChandigarh160 014India

This work describes thermal decomposition behaviour of plastic bonded explosives(PBXs) based on mixture of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HmX) and 2,4,6-triamino-1,3,5-trinitrobenzene(TATB)with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis(STA) and differential scanning calorimetry(DSC) to investigate influence of the HmX amount on thermal behavior and its kinetics. Thermogravimetric analysis(TGA) indicated that the thermal decomposition of PBXs based on mixture of HmX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HmX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HmX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HmX and TATB was observed with varying the HmX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn—Wall—Ozawa(FWO) and Kissinger-Akahira-Sunose(KAS)methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.

关键词： Plastic bonded explosives Thermogravimetric analysis Differential scanning calorimeter Thermal decomposition Kinetics

Lipid-nanoparticle-enabled nucleic acid therapeutics for liver disorders

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Acta Pharmaceutica Sinica B 2024年第7期14卷 2885-2900页

作者： Porkizhi Arjunan Durga Kathirvelu Gokulnath mahalingam Ashish Kumar Goel Uday George Zacharaiah alok srivastava Srujan marepally Center for Stem Cell Research(A Unit of inStem Bengaluru)Christian Medical College CampusBagayamVellore 632002Tamil NaduIndia manipal academy for higher education Mangalore 576104KarnatakaIndia Department of Hematology Christian Medical College&HospitalVellore 632004Tamil NaduIndia Department of Hepatology Christian Medical College&HospitalVellore 632004Tamil NaduIndia

Inherited genetic disorders of the liver pose a significant public health *** transplantation is often limited by the availability of donor livers and the exorbitant costs of immunosuppressive *** overcome these limitations,nucleic acid therapy provides a hopeful alternative that enables gene repair,gene supplementation,and gene silencing with suitable *** viral vectors are the most efficient and preferred for gene therapy,pre-existing immunity debilitating immune responses limit their *** a potential alternative,lipid nanoparticle-mediated vectors are being explored to deliver multiple nucleic acid forms,including pDNA,mRNA,siRNA,and ***,we discuss the broader applications of lipid nanoparticles,from protein replacement therapy to restoring the disease mechanism through nucleic acid delivery and gene editing,as well as multiple preclinical and clinical studies as a potential alternative to liver transplantation.

关键词： Lipid nanoparticle Liver disorders Gene therapy Gene editing Nucleic acid delivery pDNA mRNA siRNA ASO Clinical trials

Feasibility of one-shot dilation access in the pediatric age group

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World Journal of Pediatric Surgery 2022年第1期5卷 7-11页

作者： alok srivastava Krishna Kumar Yadav Anjana Singh Anoop Kumar srivastava Sanjeet Kumar Singh Urology Dr Ram Manohar Lohia Institute of Medical SciencesLucknowIndia Pediatrics Dr Ram Manohar Lohia Institute of Medical SciencesLucknowUttar PradeshIndia Department of Pathology Mayo Institute of Medical SciencesBarabankiUttar PradeshIndia Radiotherapy Dr Ram Manohar Lohia Institute of Medical SciencesLucknowIndia

Objective To compare sequential fascial dilation(SFD)versus one-shot dilation(OSD)in the pediatric patients undergoing percutaneous *** The present study is an observational *** study subjects were divided into two *** group 1,renal dilation was done using the SFD and in group 2,renal dilation was done using the *** amount of time exposed to radiation during access to pelvicalyceal system was ***,stone free rates,ancillary procedures for residual stones and hospital stay were *** Clavien-Dindo classification was used for grading the *** Radiation exposure and operative time were less in OSD group(95%confidence interval(CI)3.068 to 14.072,and 2.565 to 12.435,pmean drop of hematocrit was statistically less significant in OSD group(p=0.032).In both groups,complications,stone free rate and hospital stay were statistically *** OSD is feasible in the children with reduced radiation exposure and shorter operative *** outcome was similar to SFD.

关键词： OSD shorter pediatric

Evaluation of Inhibitory Effect of the Plant Phyllanthus amarus Against Dermatophytic Fungi microsporum gypseum

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Biomedical and Environmental Sciences 2004年第3期17卷 359-365页

作者： ANURAG AGRAWAL SHALINI srivastava J.N.srivastava m.m.SRIVASAVA Department of Chemistry Faculty of Science Dayalbagh Educational Institute Deemed University Agra-282 005 IndiaDepartment of Chemistry Faculty of Science Dayalbagh Educational Institute Deemed University Agra-282 005 IndiaDepartment of Botany Faculty of Science Dayalbagh Educational Institute Deemed University Agra-282 005 IndiaDepartment of Chemistry Faculty of Science Dayalbagh Educational Institute Deemed University Agra-282 005 India

Objective The antifungal activity of various solvent extracts (such as ether, chloroform, ethyl acetate and ethyl alcohol) of the plant Phyllanthus amarus against dermatophytic fungi microsporum gypseum was observed. method Antifungal bioassay in terms of reduction in weight, colony diameter and sporulation of the target fungal colony was carried out using Broth Dilution method. Results Root part of the plant, extracted in various organic solvents did not show any noticeable antifungal activity. The percentage inhibition observed in different solvent extracts of aerial part was found as reduction in weight: chloroform [50.3%], ethyl acetate [27.7%] and ethyl alcohol [12.1%], reduction in colony diameter: chloroform [53.4%], ethyl acetate [31.4%] and ethyl alcohol [15.0%] and reduction in sporulation: maximum inhibition in chloroform extract, at test concentration of 4000 ppm at incubation period of 8 days. Conclusion Chloroform fraction of the aerial part of the plant P. amarus shows significant inhibitory effect against dermatophytic fungi m. gypseum and requires chemical characterization for its bioactive principle.

关键词： Phyllanthus amarus Antifungal activity microsporum gypseum Skin infections

Drillability prediction in some metamorphic rocks using composite penetration rate index(CPRI)–An approach

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International Journal of mining Science and Technology 2021年第4期31卷 631-641页

作者： Gaurav Kumar srivastava m.S.R.murthy Vemavarapu Department of mining Engineering Indian Institute of Technology(Indian School of Mines)Dhanbad 826004India

Assessment of drillability of rocks is vital in the selection,operation,and performance evaluation of cutting tools used in various excavation machinery deployed in mining and *** commonly used rock drillability prediction methods,namely,drilling rate index(DRI)and Cerchar hardness index(CHI)have limitations in predicting the penetration rate due to differential wear of the cutting tool in rocks with varied hardness and *** cutting tools get blunt differently in different rocks,the stress beneath the tip of the bit decreases until it reaches a threshold value beyond which the penetration rate becomes *** this research,a new composite penetration rate index(CPRI)is suggested based on the investigations on four metamorphic rocks ***,gneiss,schist and phyllite with varied hardness-abrasivity *** penetration-time behavior was classified into active,moderate,passive,and dormant phases based on the reduction in penetration rate at different stages of drilling.A comparison of predicted penetration rate values using DRI and CPRI with actual penetration rate values clearly establishes the supremacy of ***-structure and hardness-based index was also developed and correlated with *** new indices can help predict cutting tool penetration and its consumption more accurately.

关键词： Abrasivity Hardness Drillability metamorphic rocks Composite penetration rate index(CPRI)

modulation of signal transduction pathways by natural compounds in cancer

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Chinese Journal of Natural medicines 2015年第10期13卷 730-742页

作者： alok Ranjan Neel m.Fofaria Sung-Hoon Kim Sanjay K.srivastava Department of Biomedical Sciences and Cancer Biology Center Texas Tech University Health Sciences Center Cancer Preventive material Development Research Center College of Korean Medicine Department of Pathology Kyunghee University

Cancer is generally regarded as the result of abnormal growth of cells. According to World Health Organization, cancer is the leading cause of mortality worldwide. mother nature provides a large source of bioactive compounds with excellent therapeutic efficacy. Numerous phytochemicals from nature have been investigated for anticancer properties. In this review article, we discuss several natural compounds, which have shown anti-cancer activity. Natural compounds induce cell cycle arrest, activate intrinsic and extrinsic apoptosis pathways, generate Reactive Oxygen Species(ROS), and down-regulate activated signaling pathways, resulting in inhibition of cell proliferation, progression and metastasis of cancer. Several preclinical studies have suggested that natural compounds can also increase the sensitivity of resistant cancers to available chemotherapy agents. Furthermore, combining FDA approved anti-cancer drugs with natural compounds results in improved efficacy. On the basis of these exciting outcomes of natural compounds against several cancer types, several agents have already advanced to clinical trials. In conclusion, preclinical results and clinical outcomes against cancer suggest promising anticancer efficacy of agents from natural sources.

关键词： Natural compounds Capsaicin Curcumin Diindolylmethane(DIm) Isothiocyanate Piperine Deguelin Cucurbitacin B Cancer

Synthesis and enhanced photoluminescence properties of red emitting divalent ion(Ca^(2+))doped Eu:Y_(2)O_(3)nanophosphors for optoelectronic applications

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Journal of Rare Earths 2022年第8期40卷 1187-1198页

作者： Arpita Dwivedi monika srivastava Ankur Dwivedi Amit srivastava Anurag mishra S.K.srivastava Department of Physics Institute of ScienceBanaras Hindu University(BHU)Varanasi221005India School of materials Science and Technology Indian Institute of Technology(BHU)Varanasi221005India Department of mining Engineering Indian Institute of Technology(BHU)Varanasi221005India Department of Physics TDPG College VBS Purvanchal UniversityJaunpur222001India

This work presents the synthesis of Y_(2)O_(3):Eu^(3+),χCa^(2+)(χ=0 mol%,1 mol%,3 mol%,5 mol%,7 mol%,9 mol%,11 mol%)nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic,display,and lighting *** X-ray diffraction(XRD)patterns of the proposed nanophosphor reveal its structural properties and crystalline *** transmission electron microscope(TEm)results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca^(2+).Fourier transform infrared spectroscopy(FTIR)and Raman vibrations also confirm the presence of Y-O vibration and subsequently explain the crystalline nature,structural properties,and purity of the *** the synthesized nanophosphors samples emit intense red emission at 613 nm(~5D_(0)→~7 F_(2))under excitation with 235,394 and 466 nm wavelengths of Eu^(3+)*** photoluminescence(PL)emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength,*** emission intensity of Y_(2)O_(3):Eu^(3+),χCa^(2+)(5 mol%)is increased 8-fold as compared to Eu:Y_(2)O_(3).Doping with Ca^(2+)ions enhances the emission intensity of Eu:Y_(2)O_(3)nanopho sphors due to an increase in energy transfer in Ca^(2+)→Eu^(3+)through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria *** is also observed that the optical band gap and the lifetime of the~5D_(0)level of Eu^(3+)ions in Y_(2)O_(3):Eu^(3+),xCa^(2+)nanophosphor sample gets changed with a doping conce ntration of Ca^(2+)*** also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%,***,CCT,and color purity values(>98%)show an improved red-emitting nanophosphor in the warm region of light,which m

关键词： Red emission Photoluminescence(PL) Y_(2)O_(3):Eu^(3+),xCa^(2+) Rare earths Nanophosphors LEDs