We report extracellular synthesis of silver nanoparticles (Ag-NPs) from Phoma glomerata and its efficacy against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The bacteria ...exhibiting resistance to various antibiotics showed remarkable sensitivity, when used in combination of antibiotics and Ag-NPs. Biosynthesis of Ag-NPs was carried out by challenging the fungal cell filtrate with 1 mmol l⁻¹ silver nitrate. The Ag-NPs were characterized with the help of UV-Visible spectrophotometer and Fourier transform infrared spectroscopy. Scanning electron microscopy was carried out to detect the size of Ag-NPs. Evaluation of the combined effect(s) was studied by disc diffusion method against E. coli, Staph. aureus and Ps. aeruginosa. The biosynthesis route seems to be eco-friendly and easy to scale up the process. Thus, these Ag-NPs may prove as a better candidate for drugs and can potentially eliminate the problem of chemical agents because of their biogenic nature. The bacterial resistance against antibiotics has been increasing with alarming rate. To overcome this problem, there is a pressing need to develop bactericidal agents. Ag-NPs may prove to be an answer to drug-resistant bacteria.
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In the present investigation, a series of zinc ferrite (ZnFe2O4) nanoparticles were synthesized using a facile, reproducible and scalable chemical co-precipitation route for sunlight ...assisted photocatalytic degradation application. In the present work, we have prepared ZnFe2O4 with 1:1, 1:2 and 1:3 M ratio of zinc chloride and ferric chloride respectively. This work reports the photodegradation of organic methylene blue dye molecules using ZnFe2O4 under both normal sunlight, and collected sunlight. Among other annealing temperatures, particularly the ZnFe2O4 annealed at 600 °C with a molar ratio of 1:3 showed the highest photocatalytic degradation of methylene blue. Interestingly close to 99% degradation in less than 60 min of collected sunlight illumination has been achieved indicating maximum photocatalytic activity under investigation. This expounding study will open new way of light harvesting in the field of photocatalysis which is different from common praxis.
Electrochemical impedance technique has been applied to study the corrosion behavior of galvanized steel under wet–dry cyclic conditions with various drying periods. The wet–dry cycles were carried ...out for the period of 336 h by exposure to alternate conditions of 1 h immersion in a 0.5 M NaCl solution and drying for various time periods (11, 7 and 3 h) at 298 K and 60% RH. During the wet–dry cycles, the polarization resistance,
R
p, and solution resistance,
R
s, were continuously monitored. The instantaneous corrosion rate of the coating was estimated from the obtained
R
p
−1 and time of wetness was determined from the
R
s values. The corrosion potential,
E
corr, was also measured only during the immersion period of each wet–dry cycle. In all cases, the corrosion was accelerated by the wet–dry cycles in the early stage, and started to decrease at a certain cycle and finally became similar to that at the initial cycle. The underlying steel corrosion commenced after the corrosion rate started to decrease. The shorter drying period in each cycle led to higher amount of corrosion of the coating because the surface was under wet conditions for longer periods. On the other hand, time to red rust appearance due to occurrence of the underlying steel corrosion became shorter as the drying period increased, although the total amount of corrosion was smaller. The corrosion mechanism of substrate steel under various drying conditions has been discussed, the galvanic coupling effect being taken into account.
Background & objectives: The global pandemic caused by SARS-CoV-2 virus has challenged public health system worldwide due to the unavailability of approved preventive and therapeutic options. ...Identification of neutralizing antibodies (NAb) and understanding their role is important. However, the data on kinetics of NAb response among COVID-19 patients are unclear. To understand the NAb response in COVID-19 patients, we compared the findings of microneutralization test (MNT) and plaque reduction neutralization test (PRNT) for the SARS-CoV-2. Further, the kinetics of NAb response among COVID-19 patients was assessed.
Methods: A total of 343 blood samples (89 positive, 58 negative for SARS-CoV-2 and 17 cross-reactive and 179 serum from healthy individuals) were collected and tested by MNT and PRNT. SARS-CoV-2 virus was prepared by propagating the virus in Vero CCL-81 cells. The intra-class correlation was calculated to assess the correlation between MNT and PRNT. The neutralizing endpoint as the reduction in the number of plaque count by 90 per cent (PRNT90) was also calculated.
Results: The analysis of MNT and PRNT quantitative results indicated that the intra-class correlation was 0.520. Of the 89 confirmed COVID-19 patients, 64 (71.9%) showed NAb response.
Interpretation & conclusions: The results of MNT and PRNT were specific with no cross-reactivity. In the early stages of infection, the NAb response was observed with variable antibody kinetics. The neutralization assays can be used for titration of NAb in recovered/vaccinated or infected COVID-19 patients.
Background & objectives: Since the beginning of the year 2020, the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacted humankind adversely in almost all spheres ...of life. The virus belongs to the genus Betacoronavirus of the family Coronaviridae. SARS-CoV-2 causes the disease known as coronavirus disease 2019 (COVID-19) with mild-to-severe respiratory illness. The currently available diagnostic tools for the diagnosis of COVID-19 are mainly based on molecular assays. Real-time reverse transcription-polymerase chain reaction is the only diagnostic method currently recommended by the World Health Organization for COVID-19. With the rapid spread of SARS-CoV-2, it is necessary to utilize other tests, which would determine the burden of the disease as well as the spread of the outbreak. Considering the need for the development of such a screening test, an attempt was made to develop and evaluate an IgG-based ELISA for COVID-19.
Methods: A total of 513 blood samples (131 positive, 382 negative for SARS-CoV-2) were collected and tested by microneutralization test (MNT). Antigen stock of SARS-CoV-2 was prepared by propagating the virus in Vero CCL-81 cells. An IgG capture ELISA was developed for serological detection of anti-SARS-CoV-2 IgG in serum samples. The end point cut-off values were determined by using receiver operating characteristic (ROC) curve. Inter-assay variability was determined.
Results: The developed ELISA was found to be 92.37 per cent sensitive, 97.9 per cent specific, robust and reproducible. The positive and negative predictive values were 94.44 and 98.14 per cent, respectively.
Interpretation & conclusions: This indigenously developed IgG ELISA was found to be sensitive and specific for the detection of anti-SARS-CoV-2 IgG in human serum samples. This assay may be used for determining seroprevalence of SARS-CoV-2 in a population exposed to the virus.
In recent decades, the hydrological balance/budget over Himalayan river basins has imperatively become crucial for decision-making in flood risk, water resource management, identifying ...water-sensitive areas etc. In the present study, assessment of the abating total water storage (TWS) in the three river basins viz. Indus (IRB), Ganga (GRB) and Brahmaputra (BRB) is carried out. TWS contributory factors, viz. precipitation, evaporation, runoff, snow water equivalent (SWE), soil moisture, groundwater etc., are arguably assessed. TWS anomaly and other variables are considered, and corresponding statistical seasonal (winter, premonsoon, monsoon and postmonsoon) trends are calculated using the Mann–Kendall test and the Theil-Sen estimator. Dominant monsoon precipitation over GRB and BRB and winter precipitation over IRB contribute to the replenishment of TWS with almost a month lag. Still, there are decreasing TWS trends. Most of the basins are drying, though slower during monsoon. Maximum decrease in TWS is observed in postmonsoon over IRB, while GRB and BRB show it in premonsoon. The highest intraseasonal variability is shown by precipitation, followed by runoff. Evaporation shows less variability and is less dependent. Present work will be of utmost importance for the policy or planning for governance at the state level for societal benefit.
The linkage between elevation and precipitation in the mountainous regions across the world including the Indian Himalayan Region (IHR) is very complex. Various meteorological parameters, viz., ...albedo, shortwave and longwave radiations, humidity, and mass-energy balance, play a major role in the physical processes occurring in these places. The present study examines the changes in precipitation across the IHR. The precipitation patterns act differently from east to west, and north to south due to the varying elevation. The study employed high-resolution observational gridded precipitation analyses (CHELSA) for the period 1980–2018 and the GTOPO 30 DEM for the analyses. The two major precipitating seasons over the IHR such as the monsoon (JJAS) and winter (DJF) precipitation are considered. Characteristics of the precipitation with altitude over subregions of IHR such as Shivalik’s IHR (SH), Lesser IHR (LH) and Higher IHR (HH) are presented. In addition, longitudinal variations over western IHR (WH), central IHR (CH) and eastern IHR (EH) are presented. Further, a non-parametric Mann–Kendall method has been used for trend analysis of precipitation, while the Pettitt test is used for change point detection. A positive precipitation trend is observed over HH and the western part of SH whereas a negative trend is found over the eastern part of SH. In most of the regions in SH, change in mean precipitation is observed during the recent time (1999–2018). However, HH located in the east of CH and west of EH shows a change in mean precipitation quite early (1979–1998).
In the last few decades, the utilization of fuel cells (FCs) in the automotive industry has created much attention due to easy use, modular structure, and higher efficacy. In the future, ...technological evolutions reveal that FC driven electric vehicles (EVs) will grow at a rapid pace and will become an excellent alternative to conventional vehicles. This paper discusses a detailed topological classification of the FC‐based hybrid electric vehicle (FCHEV). In these FCHEVs, one of the critical elements is the DC–DC power converter unit. The hybridization of FCs with the other power sources requires more converter units that make the system complex. A multi‐input DC–DC power converter is used to connect more than one energy source to reduce the system's complexity and improve the overall system efficacy. In this survey, numerous articles have been considered and examined vividly. An assessment of present and future scenarios of FCs based power source topologies and multi‐input DC–DC power converter topologies used in HEV is presented. This survey provides a deep insight into the topic for the researchers and engineers working in this field.
This paper deals with power generation through solar photovoltaic (SPV) system and its implementation as grid‐tied and stand‐alone systems. The major setbacks of SPV system of low conversion ...efficacy, that can be enhanced through the maximum power point tracking (MPPT) algorithm. A modified incremental conductance (MIC), termed as error based incremental conductance MPPT, has been proposed, and its behaviour is comprehensively compared with classical perturb and observe (P&O) and incremental conductance (IC) techniques. Dealing with the on‐grid application of SPV system, maximum power obtained through MIC is fed to a three‐phase grid operating at unity power factor (UPF), and the quality of grid current is monitored. Further, the power obtained through MIC finds its application in designing an SPV‐diesel generator (DG) based hybrid renewable energy system (HRES) for areas either not connected to the grid or have insufficient fossils. The stochastic nature of source or uncertain load demand leads to deviation in system frequency. This paper proposes an intelligent, comprehensive supervisory optimal‐fuzzy‐proportional‐integral‐derivative (O‐F‐PID) controller for load frequency control (LFC). The performance of proposed O‐F‐PID controller has been vividly compared with the designed optimal‐PID (O‐PID) and conventional PID (C‐PID) controllers under varying source and load demand conditions.
The rice–wheat cropping system, occupying 24 million hectares of the productive area in South Asia and China, is important for food security. Monitoring long-term changes in crop yields and ...identifying the factors associated with such changes are essential to maintain and/or improve crop productivity. Long-term experiments (LTE) provide these opportunities. We analyzed 33 rice–wheat LTE in the Indo-Gangetic Plains (IGP) of South Asia, non-IGP in India, and China to investigate the extent of yield stagnation or decline and identify possible causes of yield decline. In treatments where recommended rates of N, P and K were applied, yields of rice and wheat stagnated in 72 and 85% of the LTE, respectively, while 22 and 6% of the LTE showed a significant (
P<0.05) declining trend for rice and wheat yields, respectively. In the rice–wheat system, particularly in the IGP, rice yields are declining more rapidly than wheat. The causes of yield decline are mostly location-specific but depletion of soil K seems to be a general cause. In over 90% of the LTE, the fertilizer K rates used were not sufficient to sustain a neutral K input–output balance. Depletion of soil C, N and Zn and reduced availability of P, delays in planting, decreases in solar radiation and increases in minimum temperatures are the other potential causes of yield decline. A more efficient, integrated strategy with detailed data collection is required to identify the specific causes of yield decline. Constant monitoring of LTEs and analysis of the data using improved statistical and simulation tools should be done to unravel the cause–effect relationships of productivity and sustainability of rice–wheat systems.
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