Effect of the global electroneutrality condition on electromigration Taylor-Aris dispersion in a microcapillary with finite Debye layer thickness.

In this work, the electromigration dispersion (EMD) due to the charged electrolytes in microchannels is considered without using the thin electrical double layer assumption. The electrokinetic flow and transport of ions are actuated within a rectangular micro-/nanochannel having a negative surface charge density under the influence of an external electric field. Due to the local variation of the conductivity and the nonvalidity of the electroneutrality condition, the local electric field varies as a function of the solute concentration, wall surface charge density, valency, and Debye layer length. The resulting electrokinetic flow due to the external electric field drives the fluid along with the charged species, where the Taylor-Aris dispersion separates the solutes into their different constituents. The local concentration dependence of the electric field leads to the formation of concentration profiles that are slightly asymmetric with respect to the standard Gaussian distribution. Including a finite Debye layer thickness has an effect on the advection of the species as well as the diffusion of the species. It is found that in cases where Debye layers are thicker, the species advects faster within the microchannel. This might give valuable insights into the nature of the EMD. Our model aims to predict the evolution of ionic concentration at all positions within the channel. A study of the higher-order statistics in skewness and kurtosis has also been conducted to obtain a better understanding of the idealized model consisting of a buffer solution.

Plastic Pandemic after COVID-19: A Global Health Concern.

Abstract: COVID-19 pandemic has increased the amount of plastic burden to environment and complexities of plastic waste management. Change in behavioral pattern with advent of this pandemic led to increased practice of hygiene and increased use of different types of personal protective equipment. Unfortunately, rapid rise in production of the PPEs (like Hazmat suit, gloves, etc.) and single-use plastics used in RT-PCR and other testing are the biggest source for increased non-biodegradable plastic waste leading to amplified burden on plastic waste management. A number of measures like prioritizing the policies directed towards changes at behavioral, social and institutional level need to be started. Also, reduction in plastic waste along with proper plastic waste management policies should be implemented. To prevent the transition from one pandemic to other; improvement in government policies with public private partnership are the need of the hour.

Unraveling the Mystery of Multi-Oocyte Follicles: An Observational Study.

Introduction: Significant progress has been made in understanding oocyte fertilization and early developmental stages through in vitro fertilization (IVF) techniques. However, irregularities such as conjoined oocytes and binucleate giant oocytes, which are exceptions to the normal rule of one diploid female gamete per follicle, can potentially lead to chromosomal disorders in embryos and are recommended to be excluded from IVF attempts. The formation of primordial follicles during ovarian development, known as follicle assembly, is a critical process that establishes the ovarian follicle reserve. Multi-oocyte follicles (MOFs) containing two or more oocytes have been observed in various species, including humans, and their clinical significance on fertility and reproductive health remains unclear. Genetic and environmental factors, such as gene knockout and exposure to endocrine disruptors, have been implicated in MOF formation, but the mechanisms are not fully understood and require further investigation. Material & Method: In this Observational study, 350 slides of ovarian tissues were scanned using an AI-based automated microscope, Grundium Ocus 20, and the TIFF images were stored in cloud storage. The slides were examined using third-party software, Pathcore Seeden Viewer, for morphometry of binovular follicles. Results: In our observational study, we examined 350 ovarian tissue slides in detail by using an AI-based microscope, uncovering 22 slides from seven different tissues with binovular and multinovular oocytes. These rare multi-oocyte follicles (MOFs) challenge the conventional one-oocyte-per-follicle paradigm. MOFs are likely formed when oocytes fail to separate during cortical sex cord proliferation, regulated by factors several molecular factorsas well as environmental factors. Discussion: Multiple Ovarian Follicles (MOFs) are rare phenomena where two or more oocytes exist in one follicle. They arise when oocytes fail to separate during ovarian development, which is governed by hormones such as follicle-stimulating hormone (FSH), inhibin, BMP-15, GDF-9, and GCNF. MOFs can be caused by dysregulation and exposure to chemicals such as diethylstilbestrol (DES) and isoflavones. Binovular oocytes, which occur when two oocytes are released during ovulation and are fertilised by different sperm, can result in non-identical twins, which are influenced by genetic and environmen-tal factors such as maternal age, heredity, hormonal imbalances, and assisted reproductive techniques such as in vitro fertilisation (IVF). Polynuclear oocytes with many nuclei can develop as a result of meiotic spindle defects and environmental influences. Identifying these oocyte types may aid in improving ART results by improving knowledge of the reasons of infertility and devising appropriate interventions.

Rice-based integrated farming system improves the soil quality, bacterial community structure and system productivity under sub-humid tropical condition.

Rice-based integrated farming system improves the productivity and profitability by recycling resources efficiently. In the sub-humid tropics, rice production without sufficient nutrient replenishment often leads to soil health and fertility degradation. There has been very limited research on soil health and fertility after adopting a multi-enterprising rice-based integrated farming system (IFS), notably in the rice-fish-livestock and agroforestry system, when compared to a conventional farming system (CS). Therefore, the present study analyzed the dynamics of soil properties, soil bacterial community structure and their possible interaction mechanisms, as well as their effect on regulating soil quality and production in IFS, IFSw (water stagnant area of IFS) and CS. The results indicated that soil nutrient dynamics, bacterial diversity indices (Shannon index, Simpson index, Chao 1, ACE and Fisher index) and system productivity were higher in IFSw and IFS compared to CS. Moreover, relative operational taxonomic units of dominant bacterial genera (Chloroflexi, Acidobacteria, Verrucomicrobia, Planctomycetes, Cyanobacteria, Crenarchaeota and Gemmatimonadetes) were also higher in IFSw and IFS compared to CS. Mean soil quality index (SQI) was highest in IFSw (0.780 ± 0.201) followed by IFS (0.770 ± 0.080) and CS (0.595 ± 0.244). Moreover, rice equivalent yields (REY) and rice yields were well correlated with the higher levels of soil biological indices (SQIBiol) in IFS. Overall, our results revealed that rice-based IFS improved the soil health and fertility and ensuing crop productivity through positive interaction with soil bacterial communities and nutrient stoichiometry leading to agroecosystem sustainability.

Two-component nematic superconductivity in 4Hb-TaS2.

Most superconductors have an isotropic, single component order parameter and are well described by the standard (BCS) theory for superconductivity. Unconventional, multiple-component superconductors are exceptionally rare and are much less understood. Here, we combine scanning tunneling microscopy and angle-resolved macroscopic transport for studying the candidate chiral superconductor, 4Hb-TaS2. We reveal quasi-periodic one-dimensional modulations in the tunneling conductance accompanied by two-fold symmetric superconducting critical field. The strong modulation of the in-plane critical field, Hc2, points to a nematic, unconventional order parameter. However, the imaged vortex core is isotropic at low temperatures. We suggest a model that reconciles this apparent discrepancy and takes into account previously observed spontaneous time-reversal symmetry breaking at low temperatures. The model describes a competition between a dominating chiral superconducting order parameter and a nematic one. The latter emerges close to the normal phase. Our results strongly support the existence of two-component superconductivity in 4Hb-TaS2 and can provide valuable insights into other systems with coexistent charge order and superconductivity.

Is predictive coding falsifiable?

Predictive-coding has justifiably become a highly influential theory in Neuroscience. However, the possibility of its unfalsifiability has been raised. We argue that if predictive-coding were unfalsifiable, it would be a problem, but there are patterns of behavioural and neuroimaging data that would stand against predictive-coding. Contra (vanilla) predictive patterns are those in which the more expected stimulus generates the largest evoked-response. However, basic formulations of predictive-coding mandate that an expected stimulus should generate little, if any, prediction error and thus little, if any, evoked-response. It has, though, been argued that contra (vanilla) predictive patterns can be obtained if precision is higher for expected stimuli. Certainly, using precision, one can increase the amplitude of an evoked-response, turning a predictive into a contra (vanilla) predictive pattern. We demonstrate that, while this is true, it does not present an absolute barrier to falsification. This is because increasing precision also reduces latency and increases the frequency of the response. These properties can be used to determine whether precision-weighting in predictive-coding justifiably explains a contra (vanilla) predictive pattern, ensuring that predictive-coding is falsifiable.

Impact of long-term resource conservation techniques on biogeochemical characteristics and biological soil quality indicators in a rice green-gram farming system.

Nutrient management in resource conservation practices influence the structural and functional microbial diversities and thereby affect biological processes and biochemical properties in soil. We studied the long-term effects of resource conservation technologies on functional microbial diversity and their interactions with soil biochemical properties and enzymatic activities in tropical rice-green gram cropping system. The experiment includes seven treatments viz., conventional practice (CC), brown manuring (BM), green manuring (GM), wet direct drum sowing, zero tillage, green manuring-customized leaf colour chart based-N application (GM-CLCC-N) and biochar (BC) application. The result of the present study revealed that microbial biomass nitrogen (N), carbon (C) and phosphorus (P) in GM practice were increased by 23.3, 37.7 and 35.1%, respectively than CC. GM, BM and GM-CLCC-N treatments provide higher yields than conventional practice. The average well color development value, Shannon index and McIntosh index were significantly higher by 26.6%, 86.9% and 29.2% in GM as compared to control treatment. So, from this study we can conclude that resource conservation practices like GM, GM-CLCC N and BM in combination with chemical fertilizers provide easily decomposable carbon source to support the microbial growth. Moreover, dominance of microbial activity in biomass amended treatments (GM, GM-CLCC N and BM) indicated that these treatments could supply good amount of labile C sources on real time basis for microbial growth that may protect the stable C fraction in soil, hence could support higher yield and soil organic carbon build-up in long run under rice-green gram soil.

Soil quality assessment of lowland rice soil of eastern India: Implications of rice husk biochar application.

The role of biochar in improving the soil properties of problem soils is well known, but its long term impact on lowland rice soil is not well recognized. The soil quality indicators of biochar applied lowland rice soil are not widely reported. We developed soil quality index (SQI) of a biochar applied lowland rice soil based on 17 soil properties (indicators). Field experimentation consisted of six treatments such as 0.5, 1, 2, 4, 8 and 10 t ha-1 of rice husk derived biochar (RHB) along with control. An overall SQI was calculated encompassing the indicators using multivariate statistics (principal component analysis) and non-linear scoring functions after generation of minimum data set (MDS). Sequential application of RHB improved the SQI by 4.85% and 16.02% with application of 0.5 t ha-1 and 10 t ha-1 RHB, respectively, over the recommended dose of fertilizer (control). PCA-screening revealed that total organic carbon (Ctot), zinc (Zn), pH and bulk density (BD) were the main soil quality indicators for MDS with 27.79%, 26.61%, 23.67% and 14.47% contributions, respectively. Apart from Ctot, Zn is one of the major contributors to SQI and RHB application can potentially be an effective agronomic practice to improve Zn status in lowland rice soil. The overall SQI was significantly influenced by RHB application even at 0.5 t ha-1. The present study highlights that application of RHB improves the soil quality even in fertile, well managed, lowland rice soil.

Multi-criteria assessment to screen climate smart rice establishment techniques in coastal rice production system of India.

Introduction: Conventional rice production techniques are less economical and more vulnerable to sustainable utilization of farm resources as well as significantly contributed GHGs to atmosphere. Methods: In order to assess the best rice production system for coastal areas, six rice production techniques were evaluated, including SRI-AWD (system of rice intensification with alternate wetting and drying (AWD)), DSR-CF (direct seeded rice with continuous flooding (CF)), DSR-AWD (direct seeded rice with AWD), TPR-CF (transplanted rice with CF), TPR-AWD (transplanted rice with AWD), and FPR-CF (farmer practice with CF). The performance of these technologies was assessed using indicators such as rice productivity, energy balance, GWP (global warming potential), soil health indicators, and profitability. Finally, using these indicators, a climate smartness index (CSI) was calculated. Results and discussion: Rice grown with SRI-AWD method had 54.8 % higher CSI over FPR-CF, and also give 24.5 to 28.3% higher CSI for DSR and TPR as well. There evaluations based on the climate smartness index can provide cleaner and more sustainable rice production and can be used as guiding principle for policy makers.

Homology modeling and virtual characterization of cytochrome c nitrite reductase (NrfA) in three model bacteria responsible for short-circuit pathway, DNRA in the terrestrial nitrogen cycle.

NrfA is the molecular marker for dissimilatory nitrate reduction to ammonium (DNRA) activity, catalysing cytochrome c nitrite reductase enzyme. However, the limited study has been made so far to understand the structural homology modeling of NrfA protein in DNRA bacteria. Therefore, three model DNRA bacteria (Escherechia coli, Wolinella succinogenes and Shewanella oneidensis) were chosen in this study for in-silico protein modeling of NrfA which roughly consists of similar length of amino acids and molecular weight and they belong to two contrasting taxonomic families (γ-proteobacteria with nrfABCDEFG and ε-proteobacteria with nrfHAIJ operon). Multiple bioinformatic tools were used to examine the primary, secondary, and tertiary structure of NrfA protein using three distinct homology modeling pipelines viz., Phyre2, Swiss model and Modeller. The results indicated that NrfA protein in E. coli, W. succinogenes and S. oneidensis was mostly periplasmic and hydrophilic. Four conserved Cys-X1-X2-Cys-His motifs, one Cys-X1-X2-Cys-Lys haem-binding motif and Ca ligand were also identified in NrfA protein irrespective of three model bacteria. Moreover, 11 identical conserved amino acids sequence was observed for the first time between serine and proline in NrfA protein. Secondary structure of NrfA revealed that α-helices were observed in 77.9%, 73.4%, and 77.4% in E. coli, W. succinogenes and S. oneidensis, respectively. Ramachandran plot showed that number of residue in favored region in E. coli, W. succinogenes and S. oneidensis was 97.03%, 97.01% and 97.25%, respectively. Our findings also revealed that among three pipelines, Modeller was considered the best in-silico tool for prediction of NrfA protein. Overall, significant findings of this study may aid in the identification of future unexplored DNRA bacteria containing cytochrome c nitrite reductase. The NrfA system, which is linked to respiratory nitrite ammonification, provides an analogous target for monitoring less studied N-retention processes, particularly in agricultural ecosystems. Furthermore, one of the challenging research tasks for the future is to determine how the NrfA protein responds to redox status in the microbial cells.

Drought hotspot maps and regional drought characteristics curves: Development of a novel framework and its application to an Indian River basin undergoing climatic changes.

Drought is one of the significant natural disasters that incurs billion dollars of economic damage every year. Among all, agricultural drought needs critical attention for drought monitoring due to its direct effect on crop yield and management of irrigation water. Most of the previous studies focused on regionalizing drought using k-means, hierarchal, fuzzy, and entropy-based clustering techniques. However, these techniques are not suitable where the clusters are not separated distinctively, and the number of clusters cannot be estimated automatically. In this study, we have developed agricultural drought hotspot maps using Soil moisture deficit index (SMDI) and the regional severity (S), duration (D), and frequency (F) curves using complex network algorithm for the future warming climate (2041-2070) of the Mahanadi River basin (MRB) in India. We have used a modified dynamic Budyko (DB) hydrological model to simulate daily soil moisture at a spatial scale of 0.25° × 0.25° using input from four GCMs for the RCP 4.5 scenario. The modified DB model was calibrated and validated for the study area. The model proved to be capable of simulating the soil moisture dynamics over the basin and also effectively captured the historical droughts occurred in the basin. The drought hotspot maps of the basin suggest that the northern, south-eastern, and central parts of the basins are going to experience more number of droughts. The results suggest that for most of the clusters, the regional S-D-F curve can be utilized to understand the future drought characteristics at site-specific as well as regional scale, as the confidence band is found to be very narrow. Overall, our study provides a framework to develop regional S-D-F curve.

Evaluation of spatial spreading of phyto-available sulphur and micronutrients in cultivated coastal soils.

Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.

Anomalous magnetoresistance and magneto-thermal properties of the half-Heuslers,RPdSi (R=Y, Gd-Er).

Here, we present a detailed study on the magnetic, magneto-transport, and magneto-thermal properties of the equiatomic half-Heusler compounds with the general formula,RPdSi (R= Y and rare-earth, Gd-Er). These materials crystallize in two different superstructures of the TiNiSi-type orthorhombic unit cell with the space groupsPnmaandPmmn. Our magnetic and heat capacity measurements reveal the onset of an antiferromagnetic (AFM) ordering in the temperature range 3-16 K for all the local moments bearingRPdSi compounds, while the non-magnetic analog, YPdSi exhibits a Pauli-paramagnetic behaviour. The AFM state of these compounds can be tuned by magnetic field and temperature as demonstrated by the magnetic measurements below the Neel temperature (TN). Most importantly, this tuning of the magnetic structure is well documented in the complex temperature and field dependence of magnetoresistance (MR) and magnetocaloric effect (MCE). Our study establishes a striking correlation of the commensurate/incommensurate AFM structure with that of positive/negative MR and MCE in this series of compounds. We emphasize that such a framework applies to a large number of AFM intermetallic systems.

Combined application of ascorbic acid and endophytic N-fixing Azotobacter chroococcum Avi2 modulates photosynthetic efficacy, antioxidants and growth-promotion in rice under moisture deficit stress.

This group has previously reported the role of ascorbic acid (AA) as an antioxidant for survivability and ability to enhancing diazotrophic efficacy in Azotobacter chroococcum Avi2 under hydrogen peroxide (H2O2) stress. However, the present study showed the combined application of AA and Avi2 in drought-susceptible (IR64 and Naveen) and drought-tolerant (Ankit and Satyabhama) rice cultivars to determine their photosynthetic efficacy (chlorophyll fluorescence-imaging), antioxidants, and plant growth-promotion (PGP) under moisture deficit stress (MS, -60 kPa). The results indicated that combined application of AA and Avi2 significantly (p < 0.05) increased the total chlorophyll, relative water content, electrolytic leakage, super oxide dismutase, and catalase activities in all rice cultivars as compared to other MS treatments, whereas stress indicators like proline and H2O2 contents were proportionally increased under MS and their concentration were normalized under combined application of AA and Avi2. Photochemical quenching, non-photochemical quenching, photosynthetic electron transport rate, and the effective quantum efficiency were found to be increased significantly (p < 0.05) in Avi2 + AA as compared to other MS treatments. Moreover, rice roots harbored significantly (p < 0.05) higher copy number of nifH gene in Avi2 + AA treatment followed by Avi2 compared to flooded control and other MS treatments. Combined application of AA and Avi2 also increased the grain yield significantly (p < 0.05) by 7.09 % and 3.92 % in drought-tolerant (Ankit and Satyabhama, respectively) and 31.70 % and 34.19 % in drought-susceptible (IR64 and Naveen, respectively) rice cultivars compared to MS treatment. Overall, the present study indicated that AA along with Avi2 could be an effective formulation to alleviate MS vis à vis enhances PGP traits in rice.

Alteration in plant spacing improves submergence tolerance in Sub1 and non-Sub1 rice (cv. IR64) by better light interception and effective carbohydrate utilisation under stress.

Besides genetic improvement for developing stress-tolerant cultivars, agronomic management may also add considerable tolerance against different abiotic stresses in crop plants. In the present study, we evaluated the effect of six different spacing treatments (S1: 10 × 10 cm; S2: 15 × 10 cm; S3:15 × 15 cm; S4:20 × 10 cm; S5: 20 × 15 cm; S6: 20 × 20 cm (row-row × plant-plant)) for improving submergence tolerance in rice. A high yielding submergence intolerant rice cultivar IR64 was tested against its SUB1 QTL introgressed counterpart (IR64-Sub1) for 12 days of complete submergence for different spacing treatments in field tanks. Relatively wider spaced plants showed higher individual plant biomass and early seedling vigour, which was particularly helpful for IR64 in increasing plant survival (by 150% in S6 over S1) under 12 days of submergence, whereas the improvement was less in IR64-Sub1 (13%). Underwater radiation inside the plant canopy, particularly beyond 40 cm water depth, was significantly greater in wider spacing treatments. Leaf senescence pattern captured by SPAD chlorophyll meter reading and chlorophyll fluorescence imaging data (Fm, Fv/Fm) taken at different time intervals after stress imposition suggested that there was lesser light penetration inside the canopy of closer spaced plants, and that it might hasten leaf senescence and damage to the photosynthetic system. The initial content of total non-structural carbohydrate (NSC) was higher in wider spaced plants of IR64, and also the rate of depletion of NSC was lesser compared with closer spaced plants. In contrast, there was not much difference in NSC depletion rate under different spacing in IR64-Sub1. Further, higher antioxidant enzyme activities in wider spaced plants (both IR64 and IR64-Sub1) after de-submergence indicated better stress recovery and improved tolerance. Taken together we found that wider spacing (row-row: 20 cm and plant-plant: 15 cm and more) can significantly improve submergence tolerance ability in rice, particularly in submergence intolerant non-Sub1 cultivar like IR64, perhaps due to better underwater light penetration, delayed leaf senescence and slower depletion of NSC reserve.

Pre-monsoon spatial distribution of available micronutrients and sulphur in surface soils and their management zones in Indian Indo-Gangetic Plain.

The efficient (site-specific) management of soil nutrients is possible by understanding the spatial variability in distribution of phyto-available nutrients (here after called available nutrients) and identifying the soil management zones (MZs) of agricultural landscapes. There is need for delineating soil MZs of agricultural landscapes of the world for efficient management of soil nutrients in order to obtain sustainability in crop yield. The present study was, therefore, undertaken to understand the spatial distribution pattern of available micronutrients (zinc (Zn), boron (B), iron (Fe), manganese (Mn) and copper (Cu)), available sulphur (S), and soil properties (soil acidity (pH), electrical conductivity (EC) and organic carbon (SOC) content) in soils of intensively cultivated Indo-Gangetic Plain (IGP) of India and to delineate soil MZs for efficient management of soil nutrients. Totally, 55101 soil samples from 0-15 cm depth were obtained from 167 districts of IGP during 2014 to 2017 and were analysed for different soil parameters. Soil pH, EC and SOC content varied from 4.44 to 9.80, 0.02 to 2.13 dS m-1 and 0.10 to 1.99%, respectively. The concentration of available Zn, B, Fe, Mn, Cu and S varied from 0.01 to 3.27, 0.01 to 3.51, 0.19 to 55.7, 0.05 to 49.0, 0.01 to 5.29 and 1.01 to 108 mg kg-1, respectively. Geostatistical analysis resulted in varied distribution pattern of studied soil parameters with moderate to strong spatial dependence. The extent (% area) of nutrient deficiencies in IGP followed the order: S > Zn > B > Mn > Cu > Fe. Principal component analysis and fuzzy c-means clustering produced six distinctly different soil MZs of IGP for implementation of zone-specific soil nutrient management strategies for attaining sustainability in crop yield. The developed MZ maps could also be utilized for prioritization and rationalization of nutrients supply in IGP of India.

Metal(loid)s (As, Hg, Se, Pb and Cd) in paddy soil: Bioavailability and potential risk to human health.

Rice is one of the principal staple foods, essential for safeguarding the global food and nutritional security, but due to different natural and anthropogenic sources, it also acts as one of the biggest reservoirs of potentially toxic metal(loids) like As, Hg, Se, Pb and Cd. This review summarizes mobilization, translocation and speciation mechanism of these metal(loids) in soil-plant continuum as well as available cost-effective remediation measures and future research needs to eliminate the long-term risk to human health. High concentrations of these elements not only cause toxicity problems in plants, but also in animals that consume them and gradual deposition of these elements leads to the risk of bioaccumulation. The extensive occurrence of contaminated rice grains globally poses substantial public health risk and merits immediate action. People living in hotspots of contamination are exposed to higher health risks, however, rice import/export among different countries make the problem of global concern. Accumulation of As, Hg, Se, Pb and Cd in rice grains can be reduced by reducing their bioavailability, and controlling their uptake by rice plants. The contaminated soils can be reclaimed by phytoremediation, bioremediation, chemical amendments and mechanical measures; however these methods are either too expensive and/or too slow. Integration of innovative agronomic practices like crop establishment methods and improved irrigation and nutrient management practices are important steps to help mitigate the accumulation in soil as well as plant parts. Adoption of transgenic techniques for development of rice cultivars with low accumulation in edible plant parts could be a realistic option that would permit rice cultivation in soils with high bioavailability of these metal(loid)s.

Non-target effect of bispyribac sodium on soil microbial community in paddy soil.

Bispyribac sodium is frequently used herbicide in the rice field. Though, it has been targeted to kill rice weeds, but its non-target effect on soil microbes in paddy soil was largely unknown. Therefore, in the present study, an attempt was made to assess the non-target effect of bispyribac sodium on alteration of functional variation of soil microbial community and their correlation with microbial biomass carbon (MBC) and soil enzymes. A microcosm experiment set up was made comprising three treatments viz., control (CON) (without application of bispyribac sodium), recommended dose of bispyribac sodium (35 g ha-1) (BS), and double the dose of BS (70 g ha-1) (DBS). Results indicated that the MBC and soil enzyme activities (dehydrogenase, alkaline phosphatase and urease) in BS and DBS-treated soil were significantly (p < 0.05) declined from 1st to 30th day after application as compared to CON. Counts of heterotrophic bacteria, actinomycetes and fungal population were also decreased in BS and DBS-treated soil. The average well color development (AWCD) values derived from Biolog®ecoplates followed the order of DBS ˂ BS ˂ CON. Shannon index value was high (p ≤ 0.05) in CON compared to soil-treated with BS and DBS. Principal component analysis (PCA) showed a clear distinction of the cluster of treatments between CON, BS and DBS. Biplot analysis and heatmap suggested that carboxylic compounds and amino acids showed positive response towards BS-treated soil, whereas phenolic compounds had positive correlation with DBS-treated soil. PCA analysis indicated that oligotrophs was rich in BS-treated paddy soil, whereas copiotrophs and asymbiotic nitrogen fixers were richer in DBS treatment. Overall, the present study revealed that application of recommended dose of BS and its double dose alter the soil microbial population, enzyme activities and functional microbial diversity in paddy soil.

Practical techniques to homogenize the feed gas mixture and enhance the laser-jet interaction time in laser assisted aerodynamic separation studies.

Laser assisted aerodynamic separation not only suffers from lengthy homogenization time of the feed gas mixture but also dilution of the enriched stream when the duration of the pulsed gas jet stream far exceeds that of the emission of the pulsed laser. We report here practical techniques to overcome the former and alleviate the latter by imposing forced circulation of the feed gas prior to affecting aerodynamic separation and the rim gas during the separation process, respectively. The forced circulation of the feed gas comprising the process gas and the buffer gas resulted in drastic reduction in the time required for their thorough mixing. The recirculation of the rim gas, on the other hand, back to the pulsed nozzle through the feed vessel allowed its increased interaction with the laser beam, thereby reducing the dilution of enrichment to a certain extent.