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Four-year assessment of ambient particulate matter and trace gases in the Delhi -NCR region of India
No full textA key challenge in controlling Delhi's air quality is a lack of clear understanding of the impacts of emissions from the surrounding National Capital Region (NCR). Our objectives are to understand the limitations of publicly available data, its utility to determine pollution sources across Delhi-NCR and establish seasonal profiles of chemically active trace gases. We obtained the spatiotemporal characteristics of daily-averaged particulate matter (PM10, and PM2.5) and trace gases (NOx, O-3, SO2, and CO) within a network of 12 air quality monitoring stations located over 2000 km(2) across Delhi-NCR from January 2014 to December 2017. The highest concentrations of pollutants, except O-3, were found at Anand Vihar compared with lowest at Panchkula. A high homogeneity in PM2.5 was observed among Delhi sites as opposed to a high spatial divergence between Delhi and NCR sites. The bivariate polar plots and k-means clustering showed that PM2.5 and PM10, concentrations are dominated by local sources for all monitoring sites across Delhi-NCR. A consequence of the dominance of local source contributions to measured concentrations, except to one site remote from Delhi, is that it is not possible to evaluate the influence of regional pollution transport upon PM concentrations measured at sites within Delhi and the NCR from concentration measurements alone
Futuristic electron transport layer based on multifunctional interactions of ZnO/TCNE for stable inverted organic solar cells
Get PDFSolution-processed inverted bulk heterojunction (BHJ) organic solar cells (OSCs) are expected to play a significant role in the future of large-area flexible devices and printed electronics. In order to catch the potential of this inverted BHJ technology for use in devices, a solar cell typically requires low-resistance ohmic contact between the photoactive layers and metal electrodes, since it not only boosts performance but also protects the unstable conducting polymer-based active layer from degradation in the working environment. Interfacial engineering delivers a powerful approach to enhance the efficiency and stability of OSCs. In this study, we demonstrated the surface passivation of the ZnO electron transport layer (ETL) by an ultrathin layer of tetracyanoethylene (TCNE). We show that the TCNE film could provide a uniform and intimate interfacial contact between the ZnO and photo-active layer, simultaneously reducing the recombination of electron and holes and series resistance at the contact interface. After successful insertion of TCNE between the ZnO film and the active layer, the parameters, such as short circuit current density (J(sc)) and fill factor (FF), greatly improved, and also a high-power conversion efficiency (PCE) of similar to 8.59% was achieved, which is similar to 15% more than that of the reference devices without a TCNE layer. The devices fabricated were based on a poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b : 4,5-b ']dithiophene-2,6-diyl]-[3-fluoro-2[(2-ethylhexyl)-carbonyl]-thieno[3,4-b]thiophenediyl]] (PTB7):(6,6)-phenyl C71 butyric acid methyl ester (PC71BM) blend system. These results suggest that this surface modification strategy could be readily extended in developing large-scale roll-to-roll fabrication of OSCs
Geochemical, stable isotopic, palynological characterization of surface dry soils and atmospheric particles over Jodhpur city (Thar Desert, Rajasthan) during peak summer of 2013
No full textAtmospheric dust originating from the Thar Desert (India) acts as the local source of mineral dust in South Asia, spreading over an area of 0.32 x 10(6) km(2). Regional studies conducted during peak boreal summer are required to characterize this mineral dust that blows in form of episodic dust storms towards Indo-Gangetic Plains (IGP), using a multi-tracer approach. To achieve this goal, atmospheric PM10 particles were collected along with surface dry soils between 3 and 11 June, 2013, from in and around the Jodhpur city (26.2389 degrees N, 73.0243 degrees E) to glean elemental composition, stable isotopic and palynological (pollen types) database. Typical crustal elemental ratios, e.g. Si/Al, Ca/Al, Fe/Al, K/Al, Mg/Al, Ti/Al, varied in narrow ranges 8.1 +/- 1.21, 1.02 +/- 1.53, 0.50 +/- 0.14, 0.34 +/- 0.06, 0.19 +/- 0.06 and 0.06 +/- 0.02, respectively. Average Sr/Al, Rb/Al and Zr/Al ratios were found to be 39.70 +/- 12.24, 18.00 +/- 2.0 and 70.83 +/- 13.11 (mu g gm(-1)/wt%), respectively. Average delta C-13, delta N-15, delta S-34 values of surface soils were - 10.5 parts per thousand +/- 4.0, 11.4 parts per thousand +/- 1.6 and 3.6 parts per thousand +/- 2.1, while delta C-13 and delta N-15 of atmospheric PM10 particles varied in ranges - 25.6 parts per thousand +/- 0.67 and 9.9 parts per thousand +/- 1.7, respectively. Observed palynoassemblage indicated the open nature of vegetation that usually grows under warm-humid conditions with traces of few allergens and pathogens. Generated chemical-isotopic-pollen database could be utilized for deciphering origin of dust storms in IGP. Detailed multi-proxy characterization of mineral dust from the Thar Desert can further help to determine its role in influencing air quality and human health
Growth of SiO2 microparticles by using modified Stober method: Effect of ammonia solution concentration and TEOS concentration
Get PDFThe unique structural features and suitability of the SiO2 microparticles in different application areas have mobilized a worldwide interest in the last few decades. In this report a classical method known as the Stober method has been used to synthesize silica microspheres. These microparticles have been synthesized by the reaction of tetraethyl orthosilicate (Si(OC2H5)(4), TEOS)(silica precursor)with water in an alcoholic medium (e.g. ethanol) in the presence of KCl electrolyte and ammonia as a catalyst. It has been observed that the size of the microparticles closely depends on the amount of the TEOS and ammonia. A decrease in the size of micro particles from 2.1 mu m to 1.7 mu m has been confirmed as the amount of TEOS increases from 3.5ml to 6.4ml respectively. In similar way a decrease in the diameter of the micro particles from 2.1 mu m to 1.7 mu m has been observed with increase in the ammonia content from 3ml to 9ml
Microstructure and Wear Study of Al 7075-T6/Eggshell/SiC/Al2O3 Hybrid Composites
Get PDFIn present experimental investigation, hybrid aluminium metal matrix composites were fabricated using stir casting technique by infusing eggshell particles (0.5, 1 wt%), SiC particles (1, 1.5 wt%) and Al2O3 particles (1.5, 2.5 wt%) into Al 7075-T6 metal matrix. The developed composites were further characterized for microstructures using FESEM, X-ray diffractometry and EDS techniques. Tribological behaviour investigations were carried out using a pin-on-disk tribometer for comparative study between as-cast Al 7075-T6 alloy and Al-7075-T6/Eggshell/SiC/Al2O3 composites. During dry sliding wear test at room temperature, there was a decrease of 33% in wear rate, 20% in coefficient of friction and 20% in frictional force of composites, whereas in presence of lubricant, the developed composites exhibited maximum reduction of 85% in wear rate, 46% in coefficient of friction and 46% in frictional force as compared to their unreinforced counterparts. Due to augmented tribological properties, fabricated hybrid composites can reasonably be used for lightweight wear-resistant applications
Need of Alcohol Reference Materials and Reliable Measurement of Alcohol Content by Breath Alcohol Analyzer in India: An Overview
No full textBreath alcohol analyser is used to detect alcohol content in end-expiratory breaths in order to enforce driving regulations under the influence of alcohol legislation. The accuracy and reliability of the routine measurements of alcohol content performed with breath alcohol analyser can be achieved by the calibration of the breath alcohol analyser using standards traceable to SI reference material. Proper calibration is essential for transparency in legal verification for which reference material is needed. At international level, a number of NMIs are active to address this important measurement issue of providing accurate measurements. Several international key comparison programs have been organized so far for the determination of ethanol content in aqueous and in nitrogen/air matrix. NIST, USA; BAM, Germany; IRMM, Belgium, Portugal, INMETRO, Brazil, LGC, UK etc. have developed certain reference materials of ethanol in water solution/air with different concentration ranges. However, no such reference material is introduced in India as an indigenous standard, rather, being procured from abroad or using high purity alcohol for calibration purposes. CSIR-NPL, India, being the NMI is now focusing on establishing the calibration facility and development of SI traceable aqueous alcohol standard to provide test reliability for the testing in breath alcohol analyser. This program has a societal impact which contributes to human health and regulatory needs for the nation
A cost-effective liquid phase exfoliation process for large 2D-MoS2 nanosheets and its application in FET
Get PDF2D-TMDC materials are supposed to be suitable materials for the electronic industry requirements due to tunable bandgap. 2D-MoS2 has an advantage over the graphene as it has direct bandgap and high on/off ratio. In this work, 2D-MoS2 nanostructures have been synthesized using a simple and cost-effective liquid phase exfoliation (LPE) method in the organic solvent without any additives. The synthesized MoS2 has up to 4-layer thick nanosheets structure which is confirm by the FESEM and Raman studies. From the UV-Visible absorption spectroscopy, the bandgap of the material is found to be 1.79 eV. This synthesized material is used as the channel material in the field effect transistor. The field effect transistor (FET) device have been fabricated in the top-gate configuration. It has been found that the current on/off ratio is of the order of 10(4
ZnO-rGO nanocomposite based bioelectrode for sensitive and ultrafast detection of dopamine in human serum
No full textWe present a tyrosinase-conjugated zinc oxide-reduced graphene oxide (Tyr/ZnO-rGO) nanocomposite system as a biosensing test-bed for rapid and sensitive detection of dopamine (DA). The bioelectrodes (Tyr/ZnO-rGO/ITO) were designed by covalently immobilizing tyrosinase enzyme on spin-coated films of ZnO-rGO nanocomposite prepared via self-assembly approach. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed fast electron transfer kinetics of ZnO-rGO/ITO electrode. The response studies of the Tyr/ZnO-rGO/ITO bioelectrode revealed ultrafast (0.34 +/- 0.09 s) detection of DA in a wide linear dynamic range of 0.1-1500 pM. The significant performance of the biosensor in terms of low detection limit (8.75 +/- 0.64 pM) and high sensitivity (39.56 +/- 0.41 mu A nM(-1)) values is attributed to the fast and unhindered electron transfer mechanism of ZnO-rGO matrix having low electrochemical band gap. The nanoplatform exhibited high selectivity toward DA in human sera, and remained stable up to 3 months at 4 degrees C, representing its suitability for clinical applications
A Renowned Indian Physicst, an Obituary of Prof. S. K. Joshi OBITUARY
Get PDFShri Krishna Joshi, popularly known as Professor S.
K. Joshi, one of the best science leader and condensed
matter physicists of this country left to his heavenly abode
on 15 May 2020 at the age of 86 at his residence in
Gurugram, Haryana. It was only a few days ago before the
corona lockdown started in the country in the month of
March, and I visited him and had a long chat with him
about his health. At that time, he was suffering from cancer
in his thigh and was confined to bed. He had his usual
charismatic smile beneath which the deep pain of the illness was evident
Thin Film Research: A scientimetric Assessment of Indian Publications during 2009-18
Get PDFThe paper presents a quantitative and qualitative analysis of thin films research in India vis-a-vis the world. The publications data for the study was sourced from Scopus international bibliographical and citation database during 2009-18.The study profiles top 10 most productive countries in the subject, top 20 most productive research organizations, and 15 most productive authors. The study presents distribution of research by subject areas that intersect with thin films and by source journals. The study finds that the China and the USA are the world leader in the subject, followed by South Korea, Japan, India and others.India registered 11.04% annual average growth in the subject, five times the world average growth of 2.20%. India contributed 8.55% share of its output towards global share, 23.47% towards international collaborative papers. It averaged citations impact of 8.73 citations per paper. India contributed 4.12%share of its output as highly cited papers. Shivaji University, Kolhapur has emerged as the top ranking research organization in thin films research in the country