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The Congo Basin Zonal Overturning Circulation

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Advances in Atmospheric Sciences 2016年第6期33卷 767-782页

作者： naresh NEUPANE Department of Geological Sciences Jackson School of GeosciencesThe University of Texas at Austin

The Gulf of Guinea in the equatorial Atlantic is characterized by the presence of strong subsidence at certain times of the year. This subsidence appears in June and becomes well established from July to September. Since much of the West African monsoon flow originates over the Gulf, Guinean subsidence is important for determining moisture sources for the monsoon. Using reanalysis products, I contribute to a physical understanding of what causes this seasonal subsidence, and how it relates to precipitation distributions across West Africa. There is a seasonal zonal overturning circulation above the Congo basin and the Gulf of Guinea in the ERA-Interim, ERA-40, NCEP2, and MERRA reanalyses. The up-branch is located in the Congo basin around 20°E. Mid-tropospheric easterly flows constitute the returning-branch and sinking over the Gulf of Guinea forms the down-branch, which diverges at 2°W near the surface, with winds to the east flowing eastward to complete the circulation. This circulation is driven by surface temperature differences between the eastern Gulf and Congo basin. Land temperatures remain almost uniform, around 298 K, throughout a year, but the Guinean temperatures cool rapidly from 294 K in May to about 290 K in August. These temperature changes increase the ocean/land temperature contrast, up to 8 K, and drive the circulation. I hypothesize that when the overturning circulation is anomalously strong, the northward moisture transport and Sahelian precipitation are also strong. This hypothesis is supported by ERA-Interim and PERSIANN-CDR （Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record） data.

关键词： climate atmospheric dynamics monsoon

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

A tensile wearable SHF antenna with efficient communication in defense beacon technology

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Defence Technology（防务技术） 2024年第11期41卷 198-210页

作者： Pooja naresh Bhatt Rashmi Pandhare Department of Electronics and Communication Engineering Indian Institute of Information Technology(IIIT)NagpurMaharashtra 440001India Department of Electrical and Electronics Engineering IPS AcademyInstitute of Engineering and ScienceIndoreMP 440001 India

The study projects a flexible and compact wearable pear-shaped Super High Frequency(SHF)antenna that can provide detailed location recognition and tracking applicable to defense beacon *** mini aperture with electrical dimensions of 0.12λ_(0)×0.22λ_(0)×0.01λ_(0)attains a vast bandwidth over 3.1-34.5 GHz Super High Frequency(SHF)frequency band at S_(11)≤-10 dB,peak gain of 7.14 dBi and proportionately homogeneous radiation *** fractional bandwidth(%BW)acquired is 168%that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military *** proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is *** Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety *** flexibility is proven by analyzing the full electromagnetic simulations for various bending *** response analysis is attained with its Fidelity Factor and Group *** excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 *** is fabricated along with experimental *** the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.

关键词： Compact Defense beacon technology Link budget SAR Time domain Wearable

Synthesis of CsPbX_(3)(X=Cl/Br,Br,and Br/I)@SiO_(2)/PM M A composite films as color-conversion materials for achieving tunable multi-color and white light emission

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Nano Research 2021年第4期14卷 1187-1194页

作者： Varnakavi naresh Byung Hyo Kim Nohyun Lee School of Advanced Materials Engineering Kookmin UniversitySeoul 02707Republic of Korea Department of Organic Materials and Fiber Engineering Soongsil UniversitySeoul 06978Republic of Korea

All-inorganic cesium lead halide based perovskite nanocrystals(PNCs)exhibit promising optoelectronic properties,but their poor stability and anion exchange reaction limit their broad commercial ***,we demonstrated the successful synthesis of blue-green-red emitting CsPbX_(3)(X=Cl/Br,Br,and Br/I)PNCs via hot injection method,followed by silica-coating and embedding in poly(methylmethacrylate)(PMMA)*** photoluminescence(PL)spectra of SiO_(2)/PMMA-coated PNCs can be tuned continuously by regulating precursor composition ratio,from blue(CsPb(Cl_(0.5)/Br_(0.5))_(3);460 nm)to red(CsPb(Br_(0.4)/I_(0.6))_(3)via green(CsPbBr_(3);519 nm).The PNCs composite films exhibit improved stability(thermal-,moisture-,and photo-stability)because of the barrier formed by Si0_(2)/PMMA coating and also displayed exceptional photoluminescent quantum yield(PLQY of blue,green,and red-emitting Si0_(2)/PMMA coated PNCs are 37%,86%,and 71%,respectively)with longer lifetimes inhibiting anion ***,the PNCs-encapsulated Si0_(2)/PMMA composite films were integrated into the UV LED chip as down-converting materials to construct a prototype white-peLED *** designed white-peLED unit demonstrated bright white light generating CIE coordinates(0.349,0.350),a luminous efficiency(LE)of 39.2%and a color rendering index(CRI)of *** wide color gamut of 121.47%of NTSC and 98.56%of Rec.2020 is also achieved with the built w-LED ***,the results demonstrated that CsPbX_(3)(X=Cl/Br,Br,and Br/I)PNCs@SiO_(2)/PMMA composite films can be employed as efficient UV to visible color conversion materials for white-LEDs and backlighting.

关键词： lead halide perovskite nanocrystals hot-injection method long term stability PL quantum yield SiO_(2)/PMMA encapsulation white peLED performance

Allium cepa root tip assay in assessment of toxicity of magnesium oxide nanoparticles and microparticles

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Journal of Environmental Sciences 2018年第4期30卷 125-137页

作者： Bhanuramya Mangalampalli naresh Dumala Paramjit Grover Toxicology Unit Pharmacology and Toxicology Division CSIR-Indian Institute of Chemical Technology Academy of Scientific and Innovative Research CSIR-Indian Institute of Chemical Technology

Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide（MgO） particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano-and microparticles（NPs and MPs） at a range of exposure concentrations（12.5, 25, 50, and100 μg/m L）. The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index（MI） when compared to control cells and the effect was more significant for NPs than MPs（at p 〈 0.05）. Comet analysis revealed that the Deoxyribonucleic acid（DNA） damage in terms of percent tail DNA ranged from 6.8–30.1 over 12.5–100 μg/m L concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.

关键词： Magnesium oxide nanoparticles Allium cepa root tip assay Histochemical staining Oxidative stress Internalization of nanoparticles

C-MEMS-derived glassy carbon electrochemical biosensors for rapid detection of SARS-CoV-2 spike protein

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Microsystems & Nanoengineering 2023年第6期9卷 247-260页

作者： naresh Mandal Raja Mitra Bidhan Pramanick School of Electrical Sciences Indian Institute of Technology Goa403401 PondaGoaIndia School of Chemical and Materials Sciences Indian Institute of Technology Goa403401 PondaGoaIndia Centre of Excellence in Particulates Colloids and Interfaces Indian Institute of Technology Goa403401 PondaGoaIndia school of Interdisciplinary Life Sciences Indian Institute of Technology Goa403401 PondaGoaIndia

According to a World Health Organization(WHO)report,the world has experienced more than 766 million cases of positive SARS-CoV-2 infection and more than 6.9 million deaths due to COVID through May *** WHO declared a pandemic due to the rapid spread of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)virus,and the fight against this pandemic is not over *** reasons for virus spread include the lack of detection kits,appropriate detection techniques,delay in detection,asymptomatic cases and failure in mass *** the last 3 years,several researchers and medical companies have introduced successful test kits to detect the infection of symptomatic patients in real time,which was necessary to monitor the ***,it is also important to have information on asymptomatic cases,which can be obtained by antibody testing for the SARS-CoV-2 *** this work,we developed a simple,advantageous immobilization procedure for rapidly detecting the SARS-CoV-2 spike ***-MEMS-derived glassy carbon(GC)is used as the sensor electrode,and the detection is based on covalently linking the SARS-CoV-2 antibody to the GC *** was used as a cross-linker between the antibody and glassy carbon electrode(GCE).The binding was investigated using Fourier transform infrared spectroscopy(FTIR)characterization and cyclic voltammetric(CV)*** impedance spectroscopy(EIS)was utilized to measure the change in total impedance before and after incubation of the SARS-CoV-2 antibody with various concentrations of SARS-CoV-2 spike *** developed sensor can sense 1 fg/ml to 1µg/ml SARS-CoV-2 spike *** detection is label-free,and the chances of false positives are *** calculated LOD was~31 copies of viral RNA/*** coefficient of variation(CV)number is calculated from EIS data at 100 Hz,which is found to be 0.398%.The developed sensor may be used for mass screening because it is cost-effective.

关键词： glassy impedance linking

Historical temporal variation in precipitation over Western Himalayan Region：1857-2006

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Journal of Mountain Science 2016年第4期13卷 672-681页

作者： naresh kumar ashok kumar jaswal India Meteorological Department Lodi Road New Delhi 110003 India India Meteorological Department Pune 411005 India

This study has examined the temporal variation in monthly, seasonal & annual precipitation over the Western Himalayan Region(WHR) and the influence of global teleconnections, like the North Atlantic Oscillation(NAO) and Southern Oscillation(SO) Indices on seasonal & annual precipitation. The Mann–Kendall non-parametric test is applied for trend detection and the Pettitt–Mann–Whitney test is used to detect possible shift. Maximum entropy spectral analysis is applied to find the periodicity in annual & seasonal precipitation. The study shows a non-significant decreasing trend in annual precipitation over WHR for the period 1857-2006. However, in seasonal precipitation, a significant decreasing trend is observed in monsoon and a significant increasing trend in post-monsoon season during the same period. The significant decrease in monsoon precipitation may be due to weakening of its teleconnection with NAO as well as SO Indices mainly during last three decades. It is observed that the probable change of year in annual & monsoon precipitation over WHR is 1979. The study also shows significant periodicities of 2.3-2.9 years and of 3.9-4.7 years in annual & seasonal precipitation over WHR.

关键词： Monsoon Precipitation Western Himalayan region Temporal Variation

Investigation of Supersonic Shock Wave Loading on Thin Metallic Sheets

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Defence Technology（防务技术） 2023年第11期29卷 10-14页

作者： Khushi Ram Kartikeya Kartikeya Puneet Mahajan naresh Bhatnagar Department of Mechanical Engineering IIT DelhiNew Delhi110016India Department of Applied Mechanics IIT DelhiDelhi110016India

Shock tube experiments were carried out to investigate dynamic behavior of Ultra-high hardness(UHH)steel and Aluminium(Al) sheets of 0.8 mm thickness at 0.55, 0.9 and 1.18 MPa peak-over *** results showed that center point deflection increases with an increase in peak-over pressure for Al sheets. However, UHH steel sheets showed negligible deformation when loaded at low peak-over pressures and showed sudden brittle failure at high peak-over pressures. Similar results were obtained by quasi-static testing, UHH steel failed abruptly while Al showed ductile behavior. Results from literature indicate that to protect structures against shock loading it is necessary that they dissipate energy via plastic deformation. The Al sheets were shown to deform plastically both in quasi-static and shock loading. Thus, hardness along with ductility is required to dissipate supersonic shock waves.

关键词： Shock tube Peak-over pressure Shock wave Blast mitigation Plastic deformation

Geochemistry and petrogenesis of Neoproterozoic A-type granites at Nakora in the Malani Igneous Suite,Western Rajasthan,India

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Chinese Journal Of Geochemistry 2012年第3期31卷 221-233页

作者： naresh Kumar Vallinayagam G. Department of Geology Kurukshetra UniversityKurukshetra 136119India

The Nakora Ring Complex(NRC)(732 Ma) occurs as a part of Malani Igneous Suite(MIS) in the West-ern Rajasthan,*** complex consists of three phases(volcanic,plutonic and dyke).Geochemically,the Na-kora granites are peralkaline,metaluminous and slightly *** display geochemical characteristics of A-type granites and distinct variation trends with increasing silica *** peralkaline granites show higher concentrations of SiO2,total alkalies,TiO2,MgO,Ni,Rb,Sr,Y,Zr,Th,U,La,Ce,Nd,Eu and Yb and lower concen-trations of Al2O3,total iron,Cu and Zn than metaluminous *** content is ≥1 for peralkaline granites and <1 for peraluminous and metaluminous *** peralkaline granites are plotted between 4 to 7 kb in pressure and are emplaced at greater depths(16-28 km and 480-840℃) as compared to metaluminous granites which indicate the high fluorine content in peralkaline *** primitive mantle normalized multi-element profiles suggest that Nakora granites(peralkaline,metaluminous and peraluminous) are characterized by low La,Sr and Eu and relatively less minima of Ba,Nb and Ti which suggests the aspects related to crustal origin for Nakora *** Nakora granites are characterized as A-type granites(Whalen et al.,1987) and correspond to the field of "Within Plate Gran-ite"(Pearce et al.,1984).Geochemical,field and petrological data suggest that Nakora granites are the product of partial melting of rocks similar to Banded Gneiss from Kolar Schist Belt of India.

关键词：岩石地球化学特征碱性A型花岗岩火成岩印度新元古代套房碱性花岗岩西部