Microplastic pollution in fragile coastal ecosystems with special reference to the X-Press Pearl maritime disaster, southeast coast of India

Microplastics (MPs) are a global environmental concern and pose a serious threat to marine ecosystems. This study aimed to determine the abundance and distribution of MPs in beach sediments (12 beaches), marine biota (6 beaches) and the influence of microbes on MPs degradation in eco-sensitive Palk Bay and Gulf of Mannar coast. The mean MP abundance 65.4 ± 39.8 particles/m² in beach sediments; 0.19 ± 1.3 particles/individual fish and 0.22 ± 0.11 particles g^-1 wet weight in barnacles. Polyethylene fragments (33.4%) and fibres (48%) were the most abundant MPs identified in sediments and finfish, respectively. Histopathological examination of fish has revealed health consequences such as respiratory system damage, epithelial degradation and enterocyte vacuolization. In addition, eight bacterial and seventeen fungal strains were isolated from the beached MPs. The results also indicated weathering of MPs due to microbial interactions. Model simulations helped in tracking the fate and transboundary landfall of spilled MPs across the Indian Ocean coastline after the X-Press Pearl disaster. Due to regional circulations induced by the monsoonal wind fields, a potential dispersal of pellets has occurred along the coast of Sri Lanka, but no landfall and ecological damage are predicted along the coast of India.

Enabling ultra-low-voltage switching in BaTiO3

Single crystals of BaTiO₃ exhibit small switching fields and energies, but thin-film performance is considerably worse, thus precluding their use in next-generation devices. Here, we demonstrate high-quality BaTiO₃ thin films with nearly bulk-like properties. Thickness scaling provides access to the coercive voltages (<100 mV) and fields (<10 kV cm^-1) required for future applications and results in a switching energy of <2 J cm^-3 (corresponding to <2 aJ per bit in a 10 × 10 × 10 nm³ device). While reduction in film thickness reduces coercive voltage, it does so at the expense of remanent polarization. Depolarization fields impact polar state stability in thicker films but fortunately suppress the coercive field, thus driving a deviation from Janovec-Kay-Dunn scaling and enabling a constant coercive field for films <150 nm in thickness. Switching studies reveal fast speeds (switching times of ~2 ns for 25-nm-thick films with 5-µm-diameter capacitors) and a pathway to subnanosecond switching. Finally, integration of BaTiO₃ thin films onto silicon substrates is shown. We also discuss what remains to be demonstrated to enable the use of these materials for next-generation devices.

Enhanced photocatalytic activity of ZnO hexagonal tube/r-GO composite on degradation of organic aqueous pollutant and study of charge transport properties

ZnO hexagonal tube and ZnO/r-GO nanocomposites were synthesized by hydrothermal method and the nanostructures were characterized by XRD, UV-DRS, PL, FTIR, FESEM, and TEM techniques. The main violet emission peak of the synthesized nanostructures is due to the transition between interstitial zinc and hole (valence band) of ZnO. The potential of ZnO/r-GO nanocomposite was evaluated using methyl orange (MO) and rhodamine-B (RhB), and the results were compared with the activity of synthesized ZnO nanostructures. More than 95% of MO and RhB were by ZnO/r-GO nanocomposite and it was found to be higher than that of ZnO hexagonal tube. The degradation MO and RhB were found to follow first-order kinetics and it has a rate constant of 7.68 × 10^-2and 7.83 × 10^-2 min^-1, respectively. These results are mainly due to the enhanced charge transport property. Trapping experiments show that superoxide radical anion and hydroxide radicals are chief species responsible for the degradation of MO and RhB. The chemical stability of the nanocomposite was evaluated by cycle test experiments and it reveals that the catalyst can be reused up to few cycles without considerable loss of photocatalytic activity. This work affords a simple stratagem to integrate ZnO hexagonal tubes and r-GO nanosheets to construct effective catalysts for the degradation of organic compounds.

Isolation and biological evaluation 7-hydroxy flavone from Avicennia officinalis L: insights from extensive in vitro, DFT, molecular docking and molecular dynamics simulation studies

The flavonoid based 7-hydroxy flavone (PubChem CID: 5281894; molecular formula: C₁₅H₁₀O₃) molecule has been isolated for the first time from the methanolic extract from the leaves of Avicennia officinalis L. in the tropical mangrove ecosystem of Andaman and Nicobar Islands (ANI), India. The molecular structure of bioactive compound was characterized by spectroscopic analysis, including FT-IR, ¹H, ¹³C NMR spectroscopy and ESI-HRMS and elucidated as 7-hydroxy flavone. An anticancer activity of isolated 7-hydroxy flavone was evaluated by in vitro study against two different human cancer cell lines namely, HeLa (cervical cells) and MDA-MB231 (breast cells) and they exhibited promising anticancer activity with IC₅₀ values are 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL, respectively. The antioxidant property of 7-hydroxy flavone at a standard concentration of 50 µg, was found to be (IC₅₀) 5.5486 ± 0.81 µg/mL. In summary, this investigation provides evidence that 7-hydroxy flavone exhibits both anticancer and antioxidant properties. Meanwhile, the antimicrobial activity ability of 7-hydroxy flavone were also evaluated using three Gram positive and two Gram negative strain exhibited no antimicrobial activities. Density-functional theory (DFT) studies confirm the structure is global minima in the PES, from the optimized geometry FMO and MESP map analyzed. Further, the molecular docking and molecular dynamics simulation studies result shows that 7-hydroxy flavone has the better binding ability with anti-apoptotic Bcl-2 protein with the estimated free energy of binding of -6.3 kcal/mol. This bioactive compound may be act as drug candidate for treating various kinds of cancers. HighlightsA 7-hydroxy flavone molecule has been isolated from Avicennia officinalis.The isolated pure compound was subjected to spectral analysis such as FT-IR, ¹H NMR, ¹³C NMR spectral data and HRMS analysis for skeleton of the molecule.The anticancer activity of 7-hydroxy flavone studied against Cervical (HeLa) cancer cell lines and breast (MDA-MB231) cancer cell lines with the IC₅₀ values of 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL), respectively.The antioxidant properties of 7-hydroxy flavone were found to be (IC₅₀) 5.5486 ± 0.81 µg/mL at a standard concentration of 50 µg.DFT, molecular docking and MD simulation results explained that 7-hydroxy flavone could be the most promising candidate to inhibit the function of anti-apoptotic Bcl-2 protein in cancerous cell.Communicated by Ramaswamy H. Sarma.

Materials for a Sustainable Microelectronics Future: Electric Field Control of Magnetism with Multiferroics

This article is written on behalf of many colleagues, collaborators, and researchers in the field of complex oxides as well as current and former students and postdocs who continue to enable and undertake cutting-edge research in the field of multiferroics, magnetoelectrics, and the pursuit of electric-field control of magnetism. What I present is something that is extremely exciting from both a fundamental science and applications perspective and has the potential to revolutionize our world, particularly from a sustainability perspective. To realize this potential will require numerous new innovations, both in the fundamental science arena as well as translating these scientific discoveries into real applications. Thus, this article will attempt to bridge the gap between fundamental materials physics and the actual manifestations of the physical concepts into real-life applications. I hope this article will help spur more translational research within the broad materials community.

Fatty acid signatures of sediment microbial community in the chronically polluted mangrove ecosystem

Phospholipid fatty acid (PLFA) analysis was used to examine variation in the distribution of microbial communities in heavily polluted mangrove sediments of Thane creek, west coast of India. A total of 40 individual PLFAs representing 11 functional groups were identified in the sediment and were mainly dominated by saturated fatty acids (anaerobic prokaryotes) >50%. Significant dominance of PUFA, 16:3 ω6c (34.2%) indicators of micro-eukaryotes, in subsurface depth (p < 0.05) suggests input from the remnants of marine microalgae. Declined mean relative abundance of fungi (<6%) and actinomycetes (<1%) were detected in the sediment indicating their sensitivity to anthropic stressors. Homogenous profile of microbial diversity indicating active bioturbation. Cumulative metabolic stress evident from SAT/MUFA (>1), B/F (>1) and G⁺/G^- (<1) ratio and prolonged hypoxia to be prevalent in the creek during the study. In conclusion, PLFA signatures can thus be used as potential biomarkers of environmental monitoring and proxy for interpreting ecosystem health.

COVID-19 restrictions and their influences on ambient air, surface water and plastic waste in a coastal megacity, Chennai, India

Anthropogenic activities experienced a pause due to the nationwide lockdown, imposed to contain the rapid spread of COVID-19 in the third week of March 2020. The impacts of suspension of industrial activities, vehicular transport and other businesses for three months (25 March-30 June) on the environmental settings of Chennai, a coastal megacity was assessed. A significant reduction in the key urban air pollutants [PM_2.5 (66.5%), PM₁₀ (39.5%), NO₂ (94.1%), CO (29%), O₃ (45.3%)] was recorded as an immediate consequence of the reduced anthropogenic activities. Comparison of water quality of an urban river Adyar, between pre-lockdown and lockdown, showed a substantial drop in the dissolved inorganic N (47%) and suspended particulate matter (41%) during the latter period. During the pandemic, biomedical wastes in India showed an overall surge of 17%, which were predominantly plastic. FTIR-ATR analysis confirmed the polymers such as polypropylene (25.4%) and polyester (15.4%) in the personal protective equipment.

GROUNDWATER AND DRINKING WATER RADON CONCENTRATIONS IN THE COASTAL AND INTERIOR AREAS OF CHENNAI METRO CITY AND ITS IMPACT ON PUBLIC HEALTH

One hundred forty-eight water samples were collected from in and around Chennai and 222Rn concentrations were measured using radon emanometry method. The average 222Rn concentration was estimated to be 6.88, 2.01, 1.17, 0.19 and 0.10 Bq L-1 for borewell water, openwell water, tank water, metro water and lake water, respectively, which were within the U.S. Environmental Protection Agency's (USEPA) Standard limit of 11.1 Bq L-1 and World Health Organization (WHO) global average 10 Bq L-1. The total effective dose obtained has varied from 0 to 157.57 μSv y-1 with ±10% standard deviation. The mean values were 19.608, 8.092, 4.692, 0.761 and 0.423 μSv y-1 for closed borewell, open well water, tank water, metro water and for lake water, respectively. All these values were below the reference point 0.1 mSv y-1 (100 μSv y-1) set by WHO.

Optimized Attribute Selection Using Artificial Plant (AP) Algorithm with ESVM Classifier (AP-ESVM) and Improved Singular Value Decomposition (ISVD)-Based Dimensionality Reduction for Large Micro-array Biological Data

In the tremendous field of the bioinformatics look into, enormous volume of genetic information has been produced. Higher throughput gadgets are made accessible at lower cost made the age of Big data. In a time of developing information multifaceted nature and volume and the approach of huge information, feature selection has a key task to carry out in decreasing high dimensionality in AI issues. Dealing with such huge data has turned out to be incredibly testing strategy for choosing the exact features in enormous medical databases. Large clinical data frequently comprise of an enormous number of identifiers of the disease. Data mining when applied to clinical data for identification of diseases, a few identifiers are will not be much useful and sometimes may even have negative impacts. Consequently, when the FS is applied, it is vital as it can expel those insignificant disease identifiers. It likewise builds the adequacy of decision by a physician emotionally supportive network by viably diminishing the time of learning of the framework. In this paper, a unique approach is presented for the feature selection utilizing the Artificial Plant algorithm which uses the Enhanced Support Vector Machine classifier. The features got are additionally dimensionally decreased by presenting the Improved Singular Value Decomposition strategy; finally, enhancement is done by the outstanding BAT streamlining method. The examinations are completed with real-time large cervical cancer data and it demonstrated to be more effective than the current methods.

Spatiotemporal variations in anthropogenic marine litter pollution along the northeast beaches of India

Marine litter is widely distributed in marine environments and has been a severe concern worldwide, due to the disposal of waste from diverse sources. The severity of this threat has garnered increasing attention in India over the last decade, but the full consequences of this pollution are yet to be quantified. To estimate the spatiotemporal distribution, composition and beach quality of marine litter pollution, 17 beaches along the Hooghly estuary, a part of the Gangetic delta was studied. Marine litter was collected from 100 m long transects during two seasons (monsoon and post-monsoon). The OSPAR monitoring standard was applied to the 16,597 litter items collected, then grouped under 6 types and 44 categories. In terms of number, litter abundance was higher during monsoon (1.10 ± 0.39 items/m²) than that of post-monsoon (0.86 ± 0.32 items/m²). Most of the beaches were categorized as low cleanliness as computed by the general index and clean coast index and the good for the pellet pollution index. Hazardous litter constituted 6.5% of the total collected litter items. The model prediction revealed that the influence of high discharge from Hooghly, Rasulpur and Subarnarekha River carried enormous anthropogenic litter to the northeast beaches. The litter flux decreases with an increase in distance from the shore, and act as a sink to the sea-floor. The results denote that the distribution and typology of marine litter were representatives of household, tourism and fishing, which in turn highlights the need for better regional litter management measures. Suggested management practices include source reduction, mitigation, management of beach environment and change in littering behaviour through environmental education.

Interface enriched highly interlaced layered MoS2/NiS2 nanocomposites for the photocatalytic degradation of rhodamine B dye

In the past few decades, air and water pollution by organic dyes has become a serious concern due to their high toxicity. Removal of these organic dyes from polluted water bodies is a serious environmental concern and the development of new advanced photocatalytic materials for decomposing organic dyes can be a good solution. In this work, layered molybdenum disulfide/nickel disulfide (MoS₂/NiS₂) nanocomposites with various NiS₂ content was synthesized by a one-step hydrothermal method using citric acid as a reducing agent. The X-ray diffraction pattern shows the hexagonal and cubical crystal structure of MoS₂ and NiS₂, respectively. Morphological analysis confirms the formation of MoS₂/NiS₂ nanosheets. The elemental composition of the samples was carried out by XPS, which shows a significant interaction between NiS₂ and MoS₂. The photocatalytic performance of MoS₂/NiS₂ nanocomposites was studied by the degradation of rhodamine B (RhB). Ni-4 sample shows higher photocatalytic activity with a maximum degradation of 90.61% under visible light irradiation for 32 min.

The photocatalytic performance of MoS₂/NiS₂ nanocomposites was studied by the degradation of rhodamine B (RhB). Ni-4 sample shows higher photocatalytic activity with a maximum degradation of 90.61% under visible light irradiation for 32 min.

Engineering new limits to magnetostriction through metastability in iron-gallium alloys

Magnetostrictive materials transduce magnetic and mechanical energies and when combined with piezoelectric elements, evoke magnetoelectric transduction for high-sensitivity magnetic field sensors and energy-efficient beyond-CMOS technologies. The dearth of ductile, rare-earth-free materials with high magnetostrictive coefficients motivates the discovery of superior materials. Fe_1-xGa_x alloys are amongst the highest performing rare-earth-free magnetostrictive materials; however, magnetostriction becomes sharply suppressed beyond x = 19% due to the formation of a parasitic ordered intermetallic phase. Here, we harness epitaxy to extend the stability of the BCC Fe_1-xGa_x alloy to gallium compositions as high as x = 30% and in so doing dramatically boost the magnetostriction by as much as 10x relative to the bulk and 2x larger than canonical rare-earth based magnetostrictors. A Fe_1-xGa_x - [Pb(Mg_1/3Nb_2/3)O₃]_0.7-[PbTiO₃]_0.3 (PMN-PT) composite magnetoelectric shows robust 90° electrical switching of magnetic anisotropy and a converse magnetoelectric coefficient of 2.0 × 10^-5 s m^-1. When optimally scaled, this high coefficient implies stable switching at ~80 aJ per bit.

Assessment of biogrowth assemblages with depth in a seawater intake system of a coastal power station

Marine biogrowth infestation of a seawater intake system was investigated. A digital camera fixed onto a skid was used to record the biogrowth at intervals of 5 m up to a depth of 55 m. Divers inspected the intake shaft and collected the biogrowth samples for biomass estimation. A biomass density of 7.5 kg m^-2 and 28.2 kg m^-2 was recorded at 5 and 30 m depths respectively. Inspection by the divers revealed that hard-shelled organisms such as oysters and brown and green mussels were observed in plenty up to a thickness of 15 cm and bryozoans grew as epibionts. At lower depths (<40 m), hydroids grew on the shells of green mussels along with silt accumulation. The biofouling community was composed of 46 organisms, exhibiting variation in distribution and abundance. The study explains the extent and type of marine biogrowth phenomena with depth and describes biofouling preventive methods.Supplemental data for this article is available online at https://doi.org/10.1080/08927014.2021.1933457 .

Triple-negative breast cancers with expression of glucocorticoid receptor in immune cells show better prognosis

Background

Glucocorticoid receptor (GR) is shown to have variable frequency of expression in invasive tumors of the breast. Investigation of additional nuclear receptors like GR in receptor negative tumors like triple negative breast cancer (TNBC) may have prognostic and therapeutic significance.

Methods

Expression of GR was evaluated by immunohistochemistry in 175 tumors of invasive breast cancer with long term follow up. GR Expression was separately evaluated in invasive tumor cells, stromal cells and tumor infiltrating lymphocytes (TIL's). Staining pattern was categorised as positive when more than 1% of the cells stained in each subpopulation of cells. Disease free survival was analysed between GR positive and negative status by Kaplan Meier analysis.

Results

Of the 175 tumors, 121 (70%) were ER positive, 53 (30%) were ER negative and 29% (51) were triple negative. 74% (130/175) tumors showed expression of GR in invasive tumor cells while (84%) 147/175 had expression in TIL's. No significant difference in distribution of GR was noted between ER positive and ER negative tumors (78% vs 66%, p-0.1). Of the TNBC's 54% (28/51) and 70% (36/51) showed expression of GR in invasive tumor and TIL's respectively. Overall, GR positive tumors had significant better survival than GR negative tumors (mean survival time of 85 vs 59 months respectively, p-0.04) Contrary to the reports that GR expression in TIL's are associated with immunosuppressive activity in model systems, TNBC's with increased expression of GR in immune cells were associated with better survival (Mean survival time 74 vs 41 months, log rank test- p-0.03). TNBC tumors which were GR negative had higher lymph node metastases (p-0.04) and none of the other clinical features like age, menopausal state, tumor size and grade were different between GR positive and negative tumors within TNBC.

Conclusions

Glucocorticoids (GC) are often used to alleviate the adverse symptoms during chemotherapy. Determining the GR status is of importance due to the pro cell survival effect of the glucocorticoids mediated through GR during chemotherapy. Though GC mediated effects on chemotherapy are controversial, our results indicate favourable effects in TNBC.

The construction of a dual direct Z-scheme NiAl LDH/g-C3N4/Ag3PO4 nanocomposite for enhanced photocatalytic oxygen and hydrogen evolution

Dual direct Z-scheme photocatalysts for overall water decomposition have demonstrated strong redox abilities and the efficient separation of photogenerated electron-hole pairs. Overall water splitting utilizing NiAl-LDH-based binary and ternary nanocomposites has been extensively investigated. The synthesized binary and ternary nanocomposites were characterized via XRD, FTIR, SEM, HRTEM, XPS, UV-DRS, and photoelectrochemical measurements. The surface wettability properties of the prepared nanocomposites were measured via contact angle measurements. The application of the NiAl-LDH/g-C3N4/Ag3PO4 ternary nanocomposite was investigated for photocatalytic overall water splitting under light irradiation. In this work, we found that in the presence of Ag3PO4, the evolution of H2 and O2 is high over LCN30, and 2.8- fold (O2) and 1.4-fold (H2) activity increases can be obtained compared with the use of LCN30 alone. It is proposed that Ag3PO4 is involved in the O2 evolution reaction during water oxidation and g-C3N4 is involved in overall water splitting. Our work not only reports overall water splitting using NiAl-LDH-based nanocomposites but it also provides experimental evidence for understanding the possible reaction process and the mechanism of photocatalytic water splitting. Photoelectrochemical measurements confirmed the better H2 and O2 evolution abilities of NiAl-LDH/g-C3N4/Ag3PO4 in comparison with NiAl LDH, g-C3N4, Ag3PO4, and LCN30. The observed improvement in the gas evolution properties of NiAl LDH in the presence of Ag3PO4 is due to the formation of a dual direct Z-scheme, which allows for the easier and faster separation of charge carriers. More importantly, the LCNAP5 heterostructure shows high levels of H2 and O2 evolution, which are significantly enhanced compared with LCN30 and pure NiAl LDH.

Aggregation of Region-based and Boundary-based Knowledge Biased Segmentation for Osteoporosis Detection from X-Ray, Dual X-Ray and CT Images

BACKGROUND

Osteoporosis is a term used to represent the reduced bone density, which is caused by insufficient bone tissue production to balance the old bone tissue removal. Medical Imaging procedures such as X-Ray, Dual X-Ray and Computed Tomography (CT) scans are used widely in osteoporosis diagnosis. There are several existing procedures in practice to assist osteoporosis diagnosis, which can operate using a single imaging method.

OBJECTIVE

The purpose of this proposed work is to introduce a framework to assist the diagnosis of osteoporosis based on consenting all these X-Ray, Dual X-Ray and CT scan imaging techniques. The proposed work named "Aggregation of Region-based and Boundary-based Knowledge biased Segmentation for Osteoporosis Detection from X-Ray, Dual X-Ray and CT images" (ARBKSOD) is the integration of three functional modules.

METHODS

Fuzzy Histogram Medical Image Classifier (FHMIC), Log-Gabor Transform based ANN Training for osteoporosis detection (LGTAT) and Knowledge biased Osteoporosis Analyzer (KOA).

RESULTS

Together, all these three modules make the proposed method ARBKSOD scored the maximum accuracy of 93.11%, the highest precision value of 93.91% while processing the 6th image batch, the highest sensitivity of 92.93%, the highest specificity of 93.79% is observed during the experiment by ARBKSOD while processing the 6th image batch. The best average processing time of 10244 mS is achieved by ARBKSOD while processing the 7th image batch.

CONCLUSION

Together, all these three modules make the proposed method ARBKSOD to produce a better result.

A comprehensive in silico and in vitro studies on quinizarin: a promising phytochemical derived from Rhizophora mucronata Lam

Mangrove plants are a great source of phytomedicines, since from the beginning of human civilization and the origin of traditional medicines. In the present study, ten different mangrove leaf methanolic extracts were screened for the type of phytochemicals followed by assessing antimicrobial, anti-oxidant and anti-cancer activities. The efficient methanolic crude extract of Rhizospora mucornata was further purified and characterized for the presence of the bioactive compound. Based on UV-visible spectroscopy, FTIR, NMR and HRMS analysis, the bioactive compound was 1,4-dihydroanthraquinone; also termed as Quinizarin. This identified compound was potential in exhibiting antimicrobial, antioxidant, and cytotoxic activity. Quinizarin inhibited the growth of Bacillus cereus and Klebsiella aerogenes with minimum inhibitory concentration (MIC) of 0.78 and 1.5 mg/ml. The DPPH free radical scavenging assay revealed the maximum activity of 99.8% at the concentration of 200 µg/ml with an IC50 value of 12.67 ± 0.41 µg/ml. Cytotoxic assay against HeLa (cervical) and MDA-MB231(breast) cancer cell lines revealed IC50 values to be 4.60 ± 0.26 and 3.89 ± 0.15 µg/ml. Together the results of molecular docking and molecular dynamics simulation studies explained that Quinizarin molecule showed stronger binding affinity (-6.2 kcal/mol) and significant structural stability towards anti-apoptotic Bcl-2 protein. Thus, the study put forth the promising role of the natural molecule - Quinizarin isolated from R. mucornata in the formulation of therapeutic drugs against bacterial infections and cancer. Communicated by Ramaswamy H. Sarma.

First report of rhizome rot of banana caused by Klebsiella variicola in India

Rhizome rot or soft rot disease is one of the major problems in banana (Musa spp.) cultivation, as it causes germination failure and death of early stage plants. A roving survey conducted during 2017 to 2019 in the major banana growing states of India indicated a 5-30% incidence of rhizome rot in commercial cultivars. The symptoms observed were yellowing of leaves, necrotic drying with or without heart rot, and yellow or brown water soaked spots with dark brown margins in the rhizomes. Decay of tissues, cavity formation and brown ooze with foul smell, and toppling were also observed. To isolate bacteria, dissected diseased tissues were surface sterilized and plated on Crystal Violet Pectate (CVP) medium. Of 60 samples plated on CVP medium, three samples collected from cvs. NeyPoovan-AB (Karur, Tamil Nadu, 10°56'36.8"N;78°24'12.5"E), Grand Naine-AAA (Tiruchirappalli, Tamil Nadu, 10°47'26.1"N;78°34'14.8"E) and Thellachakkarakeli-AAA (East-Godavari, Andhra Pradesh, 16°51'32.1"N;81°46'08.4"E), did not yield any bacteria; however, when plated on nutrient agar, they produced whitish to dull white, mucoid, raised, round and translucent colonies, and three isolates were named as NPK-3-48, GTC-5 and 1-1B-3, respectively. Because these colonies were distinct from colonies obtained on CVP medium (which were analyzed and confirmed separately as Pectobaterium sp.) (Gokul et al. 2019), they were further characterized. Amplification of 16S rDNA genes of NPK-3-48, GTC-5 and 1-1B-3 isolates using universal primers (27F 5' - AGAGTTTGATCCTGGCTCAG - 3'; 1492 R 5' - GGTTACCTTGTTACGACTT - 3') and rpoB gene (Rosenblueth et al. 2004) was carried; the amplicons were sequenced and deposited in NCBI (Accessions MW036529-MW036531; MW497572-MW497574). Phylogenetic analysis of rpoB clearly showed that the isolates NPK-3-48, GTC-5, 1-1B-3 are Klebsiella variicola (Rosenblueth et al. 2004) Besides, biochemical tests also indicated that all three isolates were Gram negative, catalase positive, oxidase negative and able to utilize glucose, maltose and citrate (Ajayasree and Borkar 2018). Therefore, the above said morphological, molecular and biochemical analyses carried out indicated that NPK-3-48, GTC-5, 1-1B-3 are of K. variicola. Earlier, K. variicola causing soft rot has been reported on banana in China (Fan et al. 2016), plantain soft rot in Haiti (Fulton et al. 2020) and carrot soft rot in India (Chandrashekar et al. 2018). For pathogenicity tests, these three isolates were grown in nutrient broth for 48 h at 37±1°C and the cells were harvested by centrifugation. Five milliliters of the culture suspension (2×108 CFUmL-1) taken in a syringe was injected into rhizomes of three month old tissue cultured Grand Naine plants. Each bacterial isolate was injected into eight banana plants at soil level. Appropriate controls were maintained. Inoculated plants were maintained in a glasshouse at 32±2°C and after 30-35 days, rhizome rot symptoms appeared in all the three bacterial isolates inoculated plants but in none of the control plants. The Koch's postulates were proved by re-isolation and identification.To the best of our knowledge, this is the first report of K. variicola causing rhizome rot disease of banana in India.

Local negative permittivity and topological phase transition in polar skyrmions

Topological solitons such as magnetic skyrmions have drawn attention as stable quasi-particle-like objects. The recent discovery of polar vortices and skyrmions in ferroelectric oxide superlattices has opened up new vistas to explore topology, emergent phenomena and approaches for manipulating such features with electric fields. Using macroscopic dielectric measurements, coupled with direct scanning convergent beam electron diffraction imaging on the atomic scale, theoretical phase-field simulations and second-principles calculations, we demonstrate that polar skyrmions in (PbTiO₃)_n/(SrTiO₃)_n superlattices are distinguished by a sheath of negative permittivity at the periphery of each skyrmion. This enhances the effective dielectric permittivity compared with the individual SrTiO₃ and PbTiO₃ layers. Moreover, the response of these topologically protected structures to electric field and temperature shows a reversible phase transition from the skyrmion state to a trivial uniform ferroelectric state, accompanied by large tunability of the dielectric permittivity. Pulsed switching measurements show a time-dependent evolution and recovery of the skyrmion state (and macroscopic dielectric response). The interrelationship between topological and dielectric properties presents an opportunity to simultaneously manipulate both by a single, and easily controlled, stimulus, the applied electric field.

Accumulation and ecotoxicological risk of weathered polyethylene (wPE) microplastics on green mussel (Perna viridis)

Recent studies have shown that organisms including humans are exposed to microplastics directly or indirectly. The present study aims to examine the ingestion of these microplastics and the consequences of the same by studying the accumulation behavior of weathered Polyethylene (wPE) microplastics. The Perna viridis were exposed chronically to three different environmentally relevant concentrations of wPE for 30 days, followed by a one-week depuration phase. There was no mortality observed in the control and exposed groups, but the feeding rate was observed to have substantially decreased in the group exposed to higher concentration (3 μgL^-1) of wPE. It was also observed that a higher number of wPE particles accumulated in the intestine of exposed organisms. Interestingly, the present study revealed the presence of the substantial number of wPE particles in exposed organisms, which may adversely affect the internal organs as well as growth and reproduction. This study perceived that accumulation is marginally influenced by size of wPE. Similarly, biomarker analysis showed that wPE exposure significantly altered both the metabolism and histology of the internal organs of the exposed organisms. Overall, the study confirmed that the intestine was the most sensitive organ followed by gills, adductor muscles, and foot tissue adding new insights into the adverse effects of wPE in the marine ecosystem.