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Repercussions of solar high energy protons on ozone layer during super storms

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Research in Astronomy and Astrophysics 2019年第1期19卷 21-28页

作者： Asheesh Bhargawa Mohd Yakub ashok Kumar Singh Department of Physics University of Lucknow

We are very aware of the importance of the ozone layer, without which life on the Earth would not have evolved in the way it has. Solar storms carry energetic protons into the Earth's upper atmosphere,where they boost production of nitrogen oxides which are known as ozone killers and which ultimately increase ultraviolet(UV) radiations. In the present study, we estimate the effects of solar energetic protons during super storms(Dst index <-300 nT) over the total ozone column for the last 32 yr. We select a total of seven super storm events that occurred during solar cycles 22–24(for the last 32 yr) having Dst index <-300 nT. To that end, we apply superposed epoch analysis(SEA) to verify the impact of storm events on the quantitative variation of total ozone column and on UV radiations during super storm *** completing the empirical analysis, we conclude that the ozone column gets depleted significantly(22±6.8%) as proton density increases during super storm events and this decrement in the ozone level is further responsible for a substantial increase(26±11.2%) in peak UV radiation intensities.

关键词： Sun:particle emission Sun:solar terrestrial relations Sun:astroparticle physics Sun:Physical Data and Processes

Geochemical studies of hybrid granite from Madugulapalli area, Eastern Dharwar Craton, Southern India: Implications for crustal mixing

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Acta Geochimica 2023年第1期42卷 9-23页

作者： Nagamma J Ratnakar J Ajay kumar A ashok Ch State Mines and Geology Department 508001 NalgondaIndia Department of Geology Osmania University500007 HyderabadIndia CSIR-National Geophysical Research Institute 500007 UppalHyderabadIndia

Magma produced by melting of continental crust and mantle at the Archean-Proterozoic boundary are compositionally variable and chemical compositions provide evidence for the mixing of two sources. Understanding the composition of hybrid magma is essential for determining the comparative infl uence of crust and mantle sources during orogenesis. The hybrid granites are less documented in Indian cratons, especially less in Dharwar Craton. Here we present petrographic and whole-rock geochemical data of Madgulapalli granitic rocks situated in the NE part of the Eastern Dharwar Craton(EDC), to elucidate their petrogenesis and role in crust formation. The Madugulapalli granites(MPG) are composed chiefl y of plagioclase, quartz, and alkali feldspar with associated biotite showing alteration and inter-granular textures. Geochemically, they are metaluminous to peraluminous in nature with calc-alkaline hybrid granite. The hybrid granites exhibit both negative and positive europium anomalies;the lower Rb/Sr, Rb, Sr, and higher Sr/Y,(Dy/Yb)N ratios suggest that the interaction of older rocks with residual garnet source melted at high pressures. We hypothesize that hybrid granites are formed by interaction(e.g., metasomatism, mingling, or mixing) between parental magmas and pre-existing rocks with the infl uence of sanukitoid melts(heat source) in a subduction environment. The genesis of the hybrid granites demonstrates the mixing coupled with diff erentiation in the petrogeny’s residue system in a syn-collision setting followed by continental crust stability in EDC during the Neoarchean period.

关键词： Madugulapalli granite Hybrid granite Crustal mixing Subduction

Impact of open dumping of municipal solid waste on soil properties in mountainous region

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 725-739页

作者： Anchal Sharma ashok Kumar Gupta Rajiv Ganguly Department of Civil Engineering Jaypee University of Information Technology

This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.

关键词： Municipal solid waste (MSW) Physical characterization Soil pollution Open dumping Scanning electron microscopy (SEM) Energy disperse X-ray spectroscopy (EDS)

Bioresorbable magnesium-based alloys containing strontium doped nanohydroxyapatite promotes bone healing in critical sized bone defect in rat femur shaft

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Journal of Magnesium and Alloys 2023年第1期11卷 270-286页

作者： Shazia Shaikh Irfan Qayoom R.Sarvesha ashok Kumar Department of Biological Sciences and Bioengineering Indian Institute of Technology KanpurKanpur 208016India Centre for Environmental Science and Engineering Indian Institute of Technology KanpurKanpur 208016India Department of Materials Science and Engineering Indian Institute of Technology KanpurKanpur 208016India Center for Nanosciences Indian Institute of Technology KanpurKanpur 208016India The Mehta Family Centre for Engineering in Medicine Indian Institute of Technology KanpurKanpur 208016India

Magnesium-based biomaterials have been in extensive research for orthopedic applications for decades due to their optimal mechanical features and osteopromotive nature;nevertheless,rapid degradation restricts their clinical *** this study,pristine magnesium was purified(P-Mg)using a melt self-purification approach and reinforced using indigenously synthesized nanohydroxyapatite(HAP,0.6 wt.%)and strontium substituted nanohydroxyapatite(SrHAP,0.6 wt.%)using a low-cost stir assisted squeeze casting method to control their degradation *** electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD)examinations,all casted materials were carefully evaluated for microstructure and phase *** characteristics,in vitro degradation,and in vitro biocompatibility with murine pre-osteoblasts were also tested on the fabricated *** in vivo examination of bone formation,osteointegration,and degradation rate,the magnesium-based alloys were fabricated as small cylindrical pins with a diameter of 2.7 mm and a height of 2 *** pins were implanted in a critical-sized defect in a rat femur shaft(2.7 mm diameter and 2 mm depth)for 8 weeks and evaluated by microCT and histological evaluation for bone growth and *** compared to P-Mg and P-MgHAP,micro-CT and histological analyses revealed that the P-MgSrHAP group had the highest bone formation towards the periphery of the implant and hence maximum *** the removed pins from the bone defect were analyzed using GIXRD,they displayed hydroxyapatite peaks that were consistent with *** P-Mg,P-MgHAP,and P-MgSrHAP 8 weeks after implantation,in vivo degradation rates derived from micro-CT were around 0.6 mm/year,0.5 mm/year,and 0.1 mm/year,***,P-MgSrHAP possesses the requisite degradation rate as well as sufficient mechanical and biological properties,indicating that it has the potential to be used in the development/fabrication of bi

关键词： Magnesium purification Reinforcement Degradation rate Nanocement Bone regeneration

Luminescence Dating and Bracketing Time of the Youngest Toba Tuff Deposits in the Quaternary Sediments of Purna Alluvial Basin,Central India

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Journal of Earth Science 2022年第4期33卷 1007-1016页

作者： Singh Ajab K.Srivastava ashok Chauhan Naveen Department of Geology Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Department of Geology SGB Amravati UniversityAmravati 444602India Physical Research Laboratory Ahmedabad 380009India

Light gray to yellowish brown youngest Toba tuff(YTT)ash,preserved in the Quaternary sediments of India,have been used as a tool to know depositional and bracketing time period of the same in the sediments through applications of luminescence dating to interpret age connotation of various geological ***-and post-tephra sediments of YTT ash beds from Hudki and Sukali areas of Purna alluvial basin,Central India have been optically dated to interpret the depositional age and bracketing time of the tephra within sedimentary *** sediments are yellowish brown,thinly bedded,laminated,silty clay and host laterally extend discontinued beds of 0.15–0.20 m *** ash is light gray,fine grained and powdery in nature,massive to structureless and lacks any sign of retransportation and redeposition,hence,considered as primary in *** four sediment samples,one each from pre-and post-tephra lithounits of both the localities have been dated through optically stimulated luminescence technique(OSL)equipped with single aliquot regenerative(SAR)procedure on the feldspar *** shows pre-and post-tephra ages of 57±5 and 70±4 ka respectively for Hudki and 66±5 and 67±4 ka for Sukali *** depositional ages suggest that the ash was bracketed within sediments thousands years after YTT *** is correlatable with the previously reported depositional and absolute ages for the YTT ash from the localities of Ghoghara and Khuntheli,Son Valley;Tejpur,Madhumati River Basin and Jwalapuram,Jurreru *** ages also provide an idea about the period of existence of biological communities represented by the remains of faunal and vegetational activities before and during settlement of the YTT ash in the basin area.

关键词： youngest Toba tuff Tephra optically stimulated luminescence Quaternary sediments depositional age

Interplay between genome organization and epigenomic alterations of pericentromeric DNA in cancer

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Journal of Genetics and Genomics 2021年第3期48卷 184-197页

作者： Subhadip Kundu M.D.Ray ashok Sharma Laboratory of Chromatin and Cancer Epigenetics Department of BiochemistryAll India Institute of Medical SciencesAnsari NagarNew Delhi 110029India Department of Surgical Oncology IRCHAll India Institute of Medical SciencesAnsari NagarNew Delhi 110029India

In eukaryotic genome biology,the genomic organization inside the three-dimensional(3D)nucleus is highly complex,and whether this organization governs gene expression is poorly *** lamina(NL)is a filamentous meshwork of proteins present at the lining of inner nuclear membrane that serves as an anchoring platform for genome *** chromatin domains termed as lamina-associated domains(LADs),play a major role in silencing genes at the nuclear *** interaction of the NL and genome is dynamic and ***,many genes change their positions during developmental processes or under disease conditions such as cancer,to activate certain sorts of genes and/or silence *** heterochromatin(PCH)is mostly in the silenced region within the genome,which localizes at the nuclear *** show that several genes located at the PCH are aberrantly expressed in *** interesting question is that despite being localized in the pericentromeric region,how these genes still manage to overcome pericentromeric *** epigenetic mechanisms control the expression of the pericentromeric region,recent studies about genome organization and genome-nuclear lamina interaction have shed light on a new aspect of pericentromeric gene regulation through a complex and coordinated interplay between epigenomic remodeling and genomic organization in Cancer.

关键词： LADs Pericentromere Heterochromatin Gene regulation Epigenetics Cancer Genome organization

Emerging molecules,tools,technology,and future of surgical knife in gastroenterology

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World Journal of Gastrointestinal Surgery 2024年第4期16卷 988-998页

作者： ashok Kumar Anirudh Goyal Department of Surgical Gastroenterology Sanjay Gandhi Post Graduate Institute of Medical SciencesLucknow 226014Uttar PradeshIndia

The 21^(st) century has started with several innovations in the medical sciences,with wide applications in health care *** development has taken in the field of medicines(newer drugs/molecules),various tools and technology which has completely changed the patient management including abdominal *** for abdominal diseases has moved from maximally invasive to minimally invasive(laparoscopic and robotic)*** of the newer medicines have its impact on need for surgical *** article focuses on the development of these emerging molecules,tools,and technology and their impact on present surgical form and its future effects on the surgical intervention in gastroenterological diseases.

关键词： Newer molecules Tools and technology Gastroenterology Future of surgical knife

Automotive Visible-Light Communication: Alternative Devices and Systems

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Tsinghua Science and Technology 2023年第4期28卷 719-728页

作者： Lin Cheng Yue Wu Chenren Xu Khadija Ashraf Ashwin ashok Department of Engineering Trinity CollegeHartfordCT 06106USA Department of Computer Science Yale UniversityNew HavenCT 06520USA Department of Computer Science and Technology Peking UniversityBeijing 100084China Department of Computer Science Georgia State UniversityAtlantaGA 30302USA

Continuous advancements in visible-light communication(VLC)technology have paved the way for future high-capacity communication links that can simultaneously provide data transmission and *** is being accepted as a potential complementary technology in 5G networks,and standardization efforts through IEEE 802.15.7 are on their ***,vehicular networking applications have become increasingly complex with tight power and performance ***,devices and systems that can meet diverse vehicular networking applications are in great *** this article,we discuss three alternatives for vehicular networking applications in(1)LED–photodiode-based active VLC,(2)VLC with a multicamera array receiver,and(3)passive VLC based on decoding information from optical *** also present our recent experimental and modeling work using our camera-based and passive VLC prototype implementations.

关键词： visible-light communications automobile camera communications

Varicocele and male infertility： current concepts and Future perspectives

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Asian Journal of Andrology 2016年第2期18卷 161-162,J0002页

作者： ashok Agarwal Sandro C Esteves American Center for Reproductive Medicine Cleveland Clinic 10681 Carnegie Avenue X-11Cleveland OH 44195 USA ANDROFERT Centerfor Male Reproduction Av. Dr. Heitor Penteado 1464Camp nas SP 13075-460 Braz.

This Special Issue of Asian Journal of Andrology is fully dedicated to the thematic area of Varicocele, which has been one of the most controversial issues in the field of Urology, Andrology, and Reproductive Medicine. Recognized as a dinical entity for over a century, varicocele from Latin： varix （dilated vein） and from Greek： kele （tumor） still elicits heated debate among scientists and clinicians on an arguable negative effect on male fertility and gonadal function and has fueled thousands of scholarly articles since its first report in the 18^th century.

关键词： Varicocele male infertility