The first simultaneous measurements and analytical data on atmospheric concentrations of PM2.5, PM10, inorganic constituents, carbonaceous species, and their optical properties (aerosol optical ...depth, AOD; absorption coefficient, b abs; mass absorption efficiency, σabs; and single scattering albedo, SSA) from an urban site (Kanpur) in the Indo-Gangetic Plain are reported here. Significantly high aerosol mass concentration (>100 μg m–3) and AOD (> 0.3) are seen as a characteristic feature throughout the sampling period, from October 2008 to April 2009. The temporal variability in the mass fractions of carbonaceous species (EC, OC, and WSOC) is pronounced during October–January when emissions from biomass burning are dominant and OC is a major constituent (∼30%) of PM2.5 mass. The WSOC/OC ratio varies from 0.21 to 0.65, suggesting significant contribution from secondary organic aerosols (SOAs). The mass fraction of SO4 2– in PM2.5 (Av: 12.5%) exceeds that of NO3 – and NH4 +. Aerosol absorption coefficient (@ 678 nm) decreases from 90 Mm–1 (in December) to 20 Mm–1 (in April), and a linear regression analysis of the data for b abs and EC (n = 54) provides a measure of the mass absorption efficiency of EC (9.6 m2 g–1). In contrast, scattering coefficient (@ 678 nm) increases from 98 Mm–1 (in January) to 1056 Mm–1 (in April) and an average mass scattering efficiency of 3.0 ± 0.9 m2 g–1 is obtained for PM10 samples. The highest b scat was associated with the dust storm event (April 17, 2009) over northern Iraq, eastern Syria, and southern Turkey; thus, resulting in high SSA (0.93 ± 0.02) during March–April compared to 0.82 ± 0.04 in October–February. These results have implications to large temporal variability in the atmospheric radiative forcing due to aerosols over northern India.
This study presents a comprehensive 1 year (January 2007–March 2008) data set on the chemical composition of ambient aerosols collected from an urban location (Kanpur) in the Indo‐Gangetic Plain ...(IGP) and suggests that the varying strength of the regional emission sources, boundary layer dynamics, and formation of secondary aerosols all contribute significantly to the temporal variability in the mass concentrations of elemental carbon (EC), organic carbon (OC), and water‐soluble OC (WSOC). On average, carbonaceous aerosols contribute nearly one third of the PM10 mass during winter, whereas their fractional mass is only ∼10% during summer. A three‐ to four‐fold increase in the OC and K+ concentrations during winter and a significant linear relation between them suggest biomass burning (wood fuel and agricultural waste) emission as a dominant source. The relatively high OC/EC ratio (average: 7.4 ± 3.5 for n = 66) also supports that emissions from biomass burning are overwhelming for the particulate OC in the IGP. The WSOC/OC ratios vary from 0.21 to 0.70 over the annual seasonal cycle with relatively high ratios in the summer, suggesting the significance of secondary organic aerosols. The long‐range transport of mineral aerosols from Iran, Afghanistan, and the Thar Desert (western India) is pronounced during summer months. The temporal variability in the concentrations of selected inorganic constituents and neutralization of acidic species (SO42− and NO3−) by NH4+ (dominant during winter) and Ca2+ (in summer) reflect conspicuous changes in the source strength of anthropogenic emissions.
Bakanae disease is an emerging problem for the Basmati rice cultivation in India. Forty-seven endophytes isolated earlier along with three
Talaromyces flavus
isolates evaluated against
Fusaium ...fujikuroi
Nirenberg bakanae pathogen isolate
F250
through dual culture and enzymatic assays. Out of 50 isolates, 6 isolates namely,
Tf
1
,
Tf
2
,
Tf
3
,
Fusarium equiseti
,
Fusarium sp
. and
Trichoderma sp.
produced good inhibitory results under in vitro conditions and were proceeded with
in planta
studies and conducted microscopic studies and real-time PCR assays. Microscopic studies revealed that the defense response system of plants was activated to a longer extent in bioagent treatments, since the number of live nuclei (DAPI staining) and green stained live plant cells (FDA staining) were higher as seen in treated plants when compared to pathogen-inoculated and uninoculated control when observed under confocal laser scanning microscopy. The analysis of cell cycle-related genes expressed during the ROS activity showed increased expression of the cell cycle-related genes involved. The selected isolates were also tested under glasshouse for disease inhibition studies.
F. equiseti
,
Fusarium sp
. and
Trichoderma sp.
gave a disease inhibition of, 87%, 66% and 94%, respectively.
Tf
2
and
Tf
1
isolate dominantly inhibited the disease with 95% whereas
Tf
3
also inhibited successfully with 70%. Through the results of our study, we can deduce that the
T. flavus
(
Tf
1,
Tf
2
, Tf
3
) isolates and the endophytes
F. equiseti
,
Fusarium sp
. and
Trichoderma sp
. may represent an important biocontrol agent to control the bakanae disease of rice and also implicated that could further be befitting to capitalize them for field evaluations.
Dispersion of carbon nanotubes (CNTs) is a challenging task for their utilization in nanoscale device applications. This account reports a comparative analysis on dispersion of multiwalled carbon ...nanotubes (MWNTs) with four surfactants—Triton X-100, Tween 20, Tween 80, and sodium dodecyl sulfate (SDS). Among the four surfactants, Triton X-100 and SDS provide maximum and minimum dispersion, respectively. Dispersion of MWNTs has been characterized with UV–vis spectroscopy and transmission electron microscopy (TEM). TEM results are in agreement with the UV–vis measurements. The experimentally observed trend of dispersing power of surfactants is consistent with their chemical structures. An optimum CNT-to-surfactant ratio has been determined for each surfactant. This parameter is shown to affect the nanotube dispersion significantly. Surfactant concentration above or below this ratio is shown to deteriorate the quality of nanotube dispersion. TEM analysis of a high-surfactant-concentration sample enables us to construct a plausible mechanism for decrease in CNT dispersion at high surfactant concentration, consistent with the UV–vis observations. Temperature stability of the surfactant is another important factor affecting the quality of CNT dispersion.
Optimum CNT-to-surfactant ratio is the most important parameter affecting nanotube dispersion using surfactant. Dispersion also decreases at high surfactant concentrations due to flocculation of CNTs via extra surfactant molecules.
We present 5‐year (2001–2005) monthly mean estimates of direct radiative effects (DRE) due to aerosols over Kanpur region in the Indo‐Gangetic basin for the first time. Further, the monthly and ...annual heterogeneity of aerosol DRE has been evaluated on the basis of the anthropogenic and natural aerosol contribution. An optically equivalent model has been formulated on the basis of the surface measurements, altitude profiles of aerosol properties in conjunction with remotely retrieved aerosol parameters, and the optical properties are used to estimate the aerosol DRE at the top‐of‐atmosphere (TOA), surface and atmosphere in the shortwave (SW) and longwave (LW) region. Water‐solubles, black carbon (BC), and dust in fine (dustf) and coarse (dustc) mode are considered to be the main aerosol components on the basis of the chemical composition measurements. Anthropogenic components (scattering water‐solubles and absorbing BC) contribute more than 80% to the composite aerosol optical depth, AOD (at 0.5 μm) in the winter, whereas the natural dusts contribute more than 55% in the summer months. Aerosols induce large negative surface forcing (more than −20 W m−2) with higher values (more than −30 W m−2) during the premonsoon season, when the transported natural dusts add to the anthropogenic aerosol pollution. The SW surface cooling is partially (maximum up to 11%) compensated by LW surface heating. The SW cloudy‐sky aerosol DRE values are +1.4 ± 6.1, −23.3 ± 9.3 and +24.8 ± 9.7 W m−2 for TOA, surface and atmosphere, respectively. Annually ∼5% BC mass fraction contributes ∼9% to total AOD0.5, but ∼40% to the total aerosol surface DRE. The annual mean (±SD) TOA, surface and atmospheric clear‐sky SW anthropogenic aerosol DRE over Kanpur are +0.3 ± 2.5, −19.9 ± 9 and +20.2 ± 9.9 W m−2, respectively. Large negative surface forcing and positive atmospheric forcing in the Kanpur region raise several climatic issues. Anthropogenic aerosols contribute 65.4% to the mean (±SD) annual heating rate of 0.84 ± 0.3 K d−1 over Kanpur. A persistently large reduction of net surface radiation would affect the regional hydrological cycle through changes in evaporation and sensible heat flux. Our study assesses the aerosol direct radiative effects in Kanpur region for a 5 year period, which would provide a baseline to more thoroughly address these climate‐related issues in the future.
Differences and similarities in aerosol characteristics, for the first time, over two environmentally distinct locations in Indo-Gangetic plain (IGP) – Kanpur (KPR) (urban location) and Gandhi ...College (GC) (rural site) are examined. Aerosol optical depths (AODs) exhibit pronounced seasonal variability with higher values during winter and premonsoon. Aerosol fine mode fraction (FMF) and Ångström exponent (α) are higher over GC than KPR indicating relatively higher fine mode aerosol concentration over GC. Higher FMF over GC is attributed to local biomass burning activities. Analysis of AOD spectra revealed that aerosol size distribution is dominated by wide range of fine mode fractions or mixture of modes during winter and postmonsoon, while during premonsoon and monsoon coarse mode aerosols are more abundant. Single scattering albedo (SSA) is lower over GC than KPR. SSA spectra reveals the abundance of fine mode (coarse mode) absorbing (scattering) aerosols during winter and postmonsoon (premonsoon and monsoon). Spectral SSA features reveal that OC contribution to enhanced absorption is negligible. Analysis shows that absorbing aerosols can be classified as Mostly Black Carbon (BC), and Mixed BC and Dust over IGP. Mixed BC and dust is always higher over KPR, while Mostly BC is higher over GC throughout the year. The amount of long range transported dust exhibits a gradient between KPR (higher) and GC (lower). Results on seasonally varying aerosol types, and absorbing aerosol types and their gradients over an aerosol hotspot are important to tune models and to reduce the uncertainty in radiative and climate impact of aerosols.
•AODs exhibit prominent seasonal variation over Kanpur and Gandhi College in IGP.•Coarse mode aerosol concentration is always higher over Kanpur than Gandhi College.•Fine mode aerosols dominate IGP during winter and postmonsoon.•Absorbing aerosols over IGP are Mostly BC, and Mixed BC and Dust.•Enhanced absorption due to OC aerosols may be negligible over IGP.
Ionic liquid-based gel polymer electrolyte (GPE) has been synthesized using standard solution cast technique. Different weight percent of ionic liquid, 1-Butyl-3-methylimidazolium chloride (BMIMCl) ...and liquid electrolyte, ethylene carbonate (EC)–propylene carbonate (PC)–tetra ethyl ammonium tetra fluoro borate (TEABF
4
) was incorporated in polymer, poly(vinylidene fluoride-co-hexafluoro propylene (PVdF-HFP) to obtain mechanically stable gel polymer electrolyte film (GPE) having maximum conductivity of ~10
−3
S cm
−1
at room temperature, which is acceptable from device fabrication point of view. Potential window and ionic transference number has been obtained to examine the potential limit and ionic characteristics of optimized GPE system. Temperature dependence behavior of electrical conductivity curve follows Arrhenius nature in the temperature range of 303–373 K. Pattern of dielectric constant and its loss as a function of frequency and temperature have been studied and is being explained on the basis of electrode interfacial polarization effect. Frequency-dependent conductivity spectra obey the Jonscher’s power law. Further, optimized composition of GPE has been tested successfully for its application in supercapacitor fabrication with activated charcoal as an electrode material. Maximum specific capacitance of 118.6 mF cm
−2
equivalent to single electrode specific capacitance of 61.7 F g
−1
have been observed for the optimized GPE film.
In the category of 2D materials, MoS2 a transition metal dichalcogenide, is a novel and intriguing class of materials with interesting physicochemical properties, explored in applications ranging ...from cutting-edge optoelectronic to the frontiers of biomedical and biotechnology. MoS2 nanostructures an alternative to heavy toxic metals exhibit biocompatibility, low toxicity and high stability, and high binding affinity to biomolecules. MoS2 nanostructures provide a lot of opportunities for the advancement of novel biosensing, nanodrug delivery system, electrochemical detection, bioimaging, and photothermal therapy. Much efforts have been made in recent years to improve their physiochemical properties by developing a better synthesis approach, surface functionalization, and biocompatibility for their safe use in the advancement of biomedical applications. The understanding of parameters involved during the development of nanostructures for their safe utilization in biomedical applications has been discussed. Computational studies are included in this article to understand better the properties of MoS2 and the mechanism involved in their interaction with biomolecules. As a result, we anticipate that this combined experimental and computational studies of MoS2 will inspire the development of nanostructures with smart drug delivery systems, and add value to the understanding of two-dimensional smart nano-carriers.
This work aimed to develop a novel antimicrobial coating based on chitosan and PVA to evaluate its effect on minimally processed tomato by means of microbiological analyses. In this report an ...antimicrobial film was prepared by blending chitosan (CS) and poly(vinyl alcohol) (PVA) with glutaraldehyde as the cross-linker. The miscibility and morphology of the film were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal property of the chitosan–PVA film was examined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The microbiological screening has demonstrated the antimicrobial activity of the film against food pathogenic bacteria viz.
Escherichia coli, Staphylococcus aureus, and
Bacillus subtilis. The obtained results indicate the film may be a promising material for food packaging applications.
As part of TIGERZ campaign, latitudinal variation of aerosol optical properties was analyzed over Indo‐Gangetic Plains (IGP) to central Himalayas during premonsoon of 2008 and 2009. Measurements of ...aerosol optical depth (AOD) were performed using Aerosol Robotic Network Sun photometer at four sites with different aerosol environments. The AOD increases from Nainital located in central Himalayas to Kanpur located in IGP region. Further, aerosol size varies spatially with dominance of coarse‐mode aerosols at Kanpur compared to fine‐mode aerosols dominated at Nainital. Spectral variation of single‐scattering albedo suggests that during premonsoon, dust is the dominant species in the IGP with exception of Pantnagar, where absorbing aerosols are dominant. The optical properties of aerosols are calculated, and shortwave clear‐sky aerosol radiative forcing (ARF) is estimated. An insignificant difference is found in columnar ARF and columnar heating rate (HR) when vertical profiles of aerosols are included in radiative transfer models. Over Nainital, average ARF is estimated to be −7.61, −45.75, and 38.14 W m−2 at top of atmosphere (TOA), surface (SUR), and in the atmosphere (ATM), respectively. Average ARF is less negative at Kanpur compared to Pantnagar and Bareilly with values −17.63, −73.06, and 55.43 W m−2 at TOA, SUR, and ATM, respectively. ARF shows positive gradient from the highlands to the IGP sites; larger TOA and SUR cooling were observed at the three sites compared to the highland site. This translates into large columnar HR with estimated average values as 1.07, 1.41, 1.58, and 1.56 K d−1 for Nainital, Pantnagar, Bareilly, and Kanpur, respectively.
Key Points
First latitudinal variation of aerosols from IGP to Himalayas
First comprehensive calculations of heating rate
Large gradient in heating rates seen from IGP to Himalayas
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