Effects of the Decrease in Blood Lead Levels on Renal and Neurological Functions Among Occupationally Exposed and Unexposed Populations of South India: A Cohort Study.

INTRODUCTION: Exposure to lead in excess of the permissible limit is a known risk factor leading to preventable morbidity. The present study aimed to assess whether there is a change in the neurological and renal parameters among adults with blood lead levels (BLLs) higher than recommended at baseline and after prevention among differently exposed adults. METHODOLOGY: In the Guntur District of Andhra Pradesh, India, a cohort study was carried out in 2022-2023 among 180 adult males and females aged 20 to 60 years in three groups: direct occupational exposure, indirect occupational exposure, and no occupational exposure. If the blood levels were more than or equal to 5 mcg/dL, the participant's detailed neurological examination was done at baseline and end of follow-up. During the six-month follow-up period, health education on lead awareness was given monthly. BLLs were estimated using graphite furnace atomic absorption spectrometry (GFAAS). Serum creatinine was estimated using Jaffe's modified method. On neurological examination, reflexes, power, and sensation were assessed. The vibration perception threshold was determined using a biothesiometer. A p-value less than 0.05 was considered to be statistically significant. RESULTS: Among the 180 participants, the mean BLLs at baseline were 7.15±3.06 mcg/dL. The findings revealed a statistically significant decrease in mean BLLs at baseline to end of six-month follow-up. Despite this improvement, participants with BLLs ≥5 mcg/dL still accounted for a considerable proportion, albeit reduced, particularly in Groups 1 and 2. There were no statistically significant changes observed in the proportions of participants with abnormal serum creatinine, anemia, or abnormal neurological parameters. CONCLUSION: These results suggest that while prevention activities may effectively reduce overall BLLs, there might be challenges in completely mitigating the impact on certain health parameters, such as renal and neurological functions.

Improved deep belief network for estimating mango quality indices and grading: A computer vision-based neutrosophic approach.

This research introduces a revolutionary machinet learning algorithm-based quality estimation and grading system. The suggested work is divided into four main parts: Ppre-processing, neutroscopic model transformation, Feature Extraction, and Grading. The raw images are first pre-processed by following five major stages: read, resize, noise removal, contrast enhancement via CLAHE, and Smoothing via filtering. The pre-processed images are then converted into a neutrosophic domain for more effective mango grading. The image is processed under a new Geometric Mean based neutrosophic approach to transforming it into the neutrosophic domain. Finally, the prediction of TSS for the different chilling conditions is done by Improved Deep Belief Network (IDBN) and based on this; the grading of mango is done automatically as the model is already trained with it. Here, the prediction of TSS is carried out under the consideration of SSC, firmness, and TAC. A comparison between the proposed and traditional methods is carried out to confirm the efficacy of various metrics.

Complete atrioventricular block-an uncommon clinical presentation in an adult patient with proven dengue fever.

Dengue is a viral disease that clinically presents with fever, thrombocytopenia-related haemorrhagic complications and shock in its severest form. This female patient in her 40s primarily presented to the emergency department of the cardiac centre as syncopal attacks with a complete atrioventricular block. Temporary cardiac pacing as an emergency procedure helped to maintain cardiac rhythm and haemodynamics. A history of recent onset fever helped us to suspect and confirmed by serology for dengue pathology. Normal sinus rhythm was restored after 2 days, and we removed the temporary pacing. Cardiac arrhythmia did not recur in 6 months of follow-up. The aetiology for dengue-related cardiac arrhythmia is still not established. In the recovery phase from fever, complete heart block may show up as a primary presentation in the emergency. Its timely diagnosis and temporary pacing may allow spontaneous recovery. The inclusion of electrocardiography in dengue patient guidelines should help clinicians to dictate its treatment.

Prevalence of overweight and obesity and their effect on COVID-19 severity and hospitalization among younger than 50 years versus older than 50 years population: A systematic review and meta-analysis.

Cohort studies have shown that both overweight and obesity have their impact by increasing hospitalization with COVID-19. We conducted a systematic literature search in PubMed, Google Scholar, and MedRxiv databases following the PRISMA guidelines. Statistical analyses were performed using STATA software version 16 MP (Stata Corp, College Station, TX, USA) and Med Calc software version 22.009(Med Calc software Ltd, Ostend, Belgium). The primary outcome was to measure the prevalence of overweight and obesity and their impact on the risk of hospitalization among COVID-19 patients under and above 50 years of age. In total, 184 studies involving 2,365,377 patients were included. The prevalence of overweight was highest among those younger than 50 years of age over those older than 50 years of age, (26.33% vs. 30.46%), but there was no difference in obesity (36.30% vs. 36.02%). Overall, the pooled prevalence of overweight and obesity among hospitalized COVID-19 patients was 31.0% and 36.26%, respectively. Compared with normal weight, the odds of hospitalization with overweight (odds ratio [OR] 2.186, 95% confidence interval [CI] [1.19, 3.99], p < 0.01) and obesity (OR 3.069, 95% CI [1.67, 5.61], p < 0.001) in those younger than 50 years and obesity (OR 3.977, 95% CI [2.75, 5.73], p < 0.001) in the older than 50 years age group were significantly high. The increased prevalence of overweight and obesity among the under 50 years age group and obesity among the older than 50 years age group significantly increased the rate of COVID-19 infections, severity and hospitalization.

Postoperative acute pain management with duloxetine as compared to placebo: A systematic review with meta-analysis of randomized clinical trials.

BACKGROUND: Duloxetine has been used as an adjunct in multimodal analgesia for acute postoperative pain in clinical studies. This meta-analysis aims to conclude whether oral duloxetine, when given perioperatively, is any better than a placebo in managing postoperative pain. Effects of duloxetine on postoperative pain scores, time to first rescue analgesia, postoperative rescue analgesia consumption, side effects attributable to duloxetine, and patient satisfaction profile were assessed. METHOD: MEDLINE, Web of Science, EMBASE, Scholar Google, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched with keywords including "Duloxetine" AND "postoperative pain", "Duloxetine" AND "acute pain" and with "Duloxetine" till October 2022. This meta-analysis included randomized clinical trials in which perioperative duloxetine 60 mg per oral was administered not more than 7 days before surgery and for at least 24 after surgery but not more than 14 days after surgery. All RCTs in which the comparator is placebo and outcomes related to analgesic efficacy like pain scores, opioid consumption, and side effects of duloxetine until 48 h postoperatively were included. Data were extracted from the studies and a risk of bias summary was formed using the Cochrane Collaboration tool. Effect sizes were given as standardized mean differences for continuous outcomes and risk ratios (RR) by the Mantel-Haenszel test for the categorical outcome. Confirmation of publication bias was done by Egger's regression test (p < 0.05). If publication bias or heterogeneity was detected, the trim-and-fill method was used to calculate the adjusted effect size. Sensitivity analysis was done by leaving one out method after excluding the study with a high risk of bias. Subgroup analysis was done based on the type of surgery and gender. The study was prospectively registered in the PROSPERO under the registration number CRD42019139559. FINDINGS: 29 studies with 2043 patients met the inclusion criteria and were reviewed for this meta-analysis. Postoperative pain scores at 24 h [Std. Mean Difference (95% CI); -0.69 (-1.07, -0.32)] and at 48 h [-1.13 (-1.68, -0.58)] are significantly less with duloxetine (p-value < 0.05). Time to first rescue analgesia was significantly more in patients where duloxetine was administered [1.27 (1.10, 1.45); p-value > 0.05]. Opioid consumption up to 24 h [-1.82 (-2.46, -1.18)] and 48 h [-2.48 (-3.46, -1.50)] was significantly less (p-value < 0.05) in patients who received duloxetine. Complications and recovery profiles were similar in patients receiving either duloxetine or a placebo. INTERPRETATION: Based on GRADE findings, we conclude that there is low to moderate evidence to advocate the use of duloxetine for managing postoperative pain. Further trials are needed to replicate or refute these results based on robust methodology.

Substitutional p-Type Doping in NbS2 -MoS2 Lateral Heterostructures Grown by MOCVD.

Monolayer MoS2 has attracted significant attention owing to its excellent performance as an n-type semiconductor from the transition metal dichalcogenide (TMDC) family. It is however strongly desired to develop controllable synthesis methods for 2D p-type MoS2 , which is crucial for complementary logic applications but remains difficult. In this work, high-quality NbS2 -MoS2 lateral heterostructures are synthesized by one-step metal-organic chemical vapor deposition (MOCVD) together with monolayer MoS2 substitutionally doped by Nb, resulting in a p-type doped behavior. The heterojunction shows a p-type transfer characteristic with a high on/off current ratio of ≈104 , exceeding previously reported values. The band structure through the NbS2 -MoS2 heterojunction is investigated by density functional theory (DFT) and quantum transport simulations. This work provides a scalable approach to synthesize substitutionally doped TMDC materials and provides an insight into the interface between 2D metals and semiconductors in lateral heterostructures, which is imperative for the development of next-generation nanoelectronics and highly integrated devices.

Electrical spectroscopy of defect states and their hybridization in monolayer MoS2.

Defects in solids are unavoidable and can create complex electronic states that can significantly influence the electrical and optical properties of semiconductors. With the rapid progress in the integration of 2D semiconductors in practical devices, it is imperative to understand and characterize the influence of defects in this class of materials. Here, we examine the electrical response of defect filling and emission using deep level transient spectroscopy (DLTS) and reveal defect states and their hybridization in a monolayer MOCVD-grown material deposited on CMOS-compatible substrates. Supported by aberration-corrected STEM imaging and theoretical calculations, we find that neighboring sulfur vacancy pairs introduce additional shallow trap states via hybridization of individual vacancy levels. Even though such vacancy pairs only represent ~10% of the total defect concentration, they can have a substantial influence on the off currents and switching slopes of field-effect transistors based on 2D semiconductors. Our technique, which can quantify the energy states of different defects and their interactions, allows rapid and nondestructive electrical characterization of defect states important for the defect engineering of 2D semiconductors.

High durability and stability of 2D nanofluidic devices for long-term single-molecule sensing.

Nanopores in two-dimensional (2D) membranes hold immense potential in single-molecule sensing, osmotic power generation, and information storage. Recent advances in 2D nanopores, especially on single-layer MoS2, focus on the scalable growth and manufacturing of nanopore devices. However, there still remains a bottleneck in controlling the nanopore stability in atomically thin membranes. Here, we evaluate the major factors responsible for the instability of the monolayer MoS2 nanopores. We identify chemical oxidation and delamination of monolayers from their underlying substrates as the major reasons for the instability of MoS2 nanopores. Surface modification of the substrate and reducing the oxygen from the measurement solution improves nanopore stability and dramatically increases their shelf-life. Understanding nanopore growth and stability can provide insights into controlling the pore size, shape and can enable long-term measurements with a high signal-to-noise ratio and engineering durable nanopore devices.

Disorder-induced bulk photovoltaic effect in a centrosymmetric van der Waals material.

Sunlight is widely seen as one of the most abundant forms of renewable energy, with photovoltaic cells based on pn junctions being the most commonly used platform attempting to harness it. Unlike in conventional photovoltaic cells, the bulk photovoltaic effect (BPVE) allows for the generation of photocurrent and photovoltage in a single material without the need to engineer a pn junction and create a built-in electric field, thus offering a solution that can potentially exceed the Shockley-Queisser efficiency limit. However, it requires a material with no inversion symmetry and is therefore absent in centrosymmetric materials. Here, we demonstrate that breaking the inversion symmetry by structural disorder can induce BPVE in ultrathin PtSe2, a centrosymmetric semiconducting van der Waals material. Homogenous illumination of defective PtSe2 by linearly and circularly polarized light results in a photoresponse termed as linear photogalvanic effect (LPGE) and circular photogalvanic effect (CPGE), which is mostly absent in the pristine crystal. First-principles calculations reveal that LPGE originates from Se vacancies that act as asymmetric scattering centers for the photo-generated electron-hole pairs. Our work emphasizes the importance of defects to induce photovoltaic functionality in centrosymmetric materials and shows how the range of materials suitable for light sensing and energy-harvesting applications can be extended.

Utility of telemedicine for providing Obstetrics and Gynecology services during the COVID-19 pandemic-A single center experience from a tertiary care teaching hospital located in South India.

BACKGROUND: The COVID-19 pandemic greatly impeded the provision of public healthcare within a healthcare system that was already under considerable strain. Routine patient care services were impacted during that time, leading to the promotion of telemedicine as a means of maintaining uninterrupted healthcare services. Telemedicine involves the utilization of electronic technology and communication to provide health-related information and medical care to individuals who are physically separated from healthcare professionals. MATERIALS AND METHODS: To assess the feasibility of utilizing telemedicine for providing women's health services, we conducted a six-month analysis of data collected from the Department of Obstetrics and Gynecology's teleconsultation application at AIIMS, Mangalagiri. Our objective was to evaluate the practicality of telemedicine in delivering diverse healthcare services to women. Our institution offered two types of telehealth services: a "call-based"approach and an "app-based" approach. We examined several parameters within the data, including the distribution of ages, the geographic locations of teleconsultation registrations, whether the registrations were new or follow-up cases, the various presenting complaints, the recommended treatments, the number of consultations (single or multiple), and whether cases required in-person or hospital visits. Additionally, we also compared patient responses between these two modalities. RESULTS: The "call-based" consultation method was preferred by the majority of our patients (94%). The registered cases included both related to obstetrics and gynecology, with a higher proportion of complaints relating to gynecological issues (82.5%). We were able to make a diagnosis in 77% of cases, while in 20% of cases, additional physical examinations and diagnostic tests were necessary. Follow-up appointments were recommended for 53% of patients. The success rate of consultations for patients seeking obstetrics and gynecology services showed a statistically significant difference (P value < 0.001). The vast majority of patients (99%) expressed high satisfaction with the consultation process. CONCLUSION: During the COVID-19 pandemic, telemedicine proved to be an effective approach in mitigating the overcrowding of hospitals and preventing the spread of infection. Its success suggests that telemedicine can be a viable option for managing elective gynecology matters and low-risk obstetric cases in the future, thereby alleviating the strain on healthcare systems.

Mysterious Outbreak of Acute Neurological Syndrome in Eluru, Andhra Pradesh, India: A Post-outbreak Geo-Spatial Analysis.

BACKGROUND: An outbreak characterized by sudden-onset seizures, loss of consciousness, and complete recovery within a few hours was reported from Eluru town in Andhra Pradesh on December 6, 2020. This study was conducted to assess the environmental correlates of the outbreak using geo-mapping tools. METHODS: A post-outbreak survey was conducted among affected cases in January-February, 2021. A house-to-house survey tool collected information on demographics, clinical profile, and environmental and psychological aspects (Impact of Event Scale). Geo-mapping and news media content analyses were done using QGIS and Atlas.ti software, respectively. RESULTS: A total of 394 cases were studied. The median (interquartile range [IQR]) age of the participants was 27 (17-39) years and comprised mostly male students. There was no clustering of cases within 48 hours of illness onset in the spatial analysis. Loss of consciousness was the first (50.7%) and the most common symptom. All cases were taken to a health facility and were discharged after a median duration of 48 minutes. COVID-19-related and environmental practices were not associated with the clinical manifestations. Awareness about pesticides was low. The outbreak reportedly had a psychological impact on 24.4% of the participants. The most common co-occurring themes in the news media analysis were water contamination and pesticides. CONCLUSION: The geo-spatial analysis did not find case clustering or points of convergence during the incubation period. The geo-locations did not distribute around water bodies or suspected landmarks although news media projected water contamination and pesticides as probable causes of the outbreak.

Wafer-scale MoS2 with water-vapor assisted showerhead MOCVD.

Among numerous thin film synthesis methods, metalorganic chemical vapor deposition performed in a showerhead reactor is the most promising one for broad use in scalable and commercially adaptable two-dimensional material synthesis processes. Adapting the most efficient monolayer growth methodologies from tube-furnace systems to vertical-showerhead geometries allows us to overcome the intrinsic process limitations and improve the overall monolayer yield quality. Here, we demonstrate large-area, monolayer molybdenum disulphide growth by combining gas-phase precursor supply with unique tube-furnace approaches of utilizing sodium molybdate pre-seeding solution spincoated on a substrate along with water vapor added during the growth step. The engineered process yields a high-quality, 4-inch scale monolayer film on sapphire wafers. The monolayer growth coverage, average crystal size and defect density were evaluated using Raman and photoluminescence spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and scanning transmission electron microscopy imaging. Our findings provide a direct step forward toward developing a reproducible and large-scale MoS2 synthesis with commercial showerhead reactors.

High-Throughput Nanopore Fabrication and Classification Using Xe-Ion Irradiation and Automated Pore-Edge Analysis.

Large-area nanopore drilling is a major bottleneck in state-of-the-art nanoporous 2D membrane fabrication protocols. In addition, high-quality structural and statistical descriptions of as-fabricated porous membranes are key to predicting the corresponding membrane-wide permeation properties. In this work, we investigate Xe-ion focused ion beam as a tool for scalable, large-area nanopore fabrication on atomically thin, free-standing molybdenum disulfide. The presented irradiation protocol enables designing ultrathin membranes with tunable porosity and pore dimensions, along with spatial uniformity across large-area substrates. Fabricated nanoporous membranes are then characterized using scanning transmission electron microscopy imaging, and the observed nanopore geometries are analyzed through a pore-edge detection and analysis script. We further demonstrate that the obtained structural and statistical data can be readily passed on to computational and analytical tools to predict the permeation properties at both individual pore and membrane-wide scales. As an example, membranes featuring angstrom-scale pores are investigated in terms of their emerging water and ion flow properties through extensive all-atom molecular dynamics simulations. We believe that the combination of experimental and analytical approaches presented here will yield accurate physics-based property estimates and thus potentially enable a true function-by-design approach to fabrication for applications such as osmotic power generation and desalination/filtration.

Ion-Induced Surface Charge Dynamics in Freestanding Monolayers of Graphene and MoS_{2} Probed by the Emission of Electrons.

We compare the ion-induced electron emission from freestanding monolayers of graphene and MoS_{2} to find a sixfold higher number of emitted electrons for graphene even though both materials have similar work functions. An effective single-band Hubbard model explains this finding by a charge-up in MoS_{2} that prevents low energy electrons from escaping the surface within a period of a few femtoseconds after ion impact. We support these results by measuring the electron energy distribution for correlated pairs of electrons and transmitted ions. The majority of emitted primary electrons have an energy below 10 eV and are therefore subject to the dynamic charge-up effects at surfaces.

The Post-Vaccination Quantitative Total Immunoglobulin Levels against SARS-CoV-2 in Healthcare Workers: A Multi-Centric Cohort Study in India.

Healthcare workers (HCWs) in India received the AZD1222 and BBV152 vaccines from January 2021 onwards. The objective of this study was to compare the immune response (seropositivity rate and geometric mean titer (GMT), and 95% confidence interval (CI)] against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in HCWs who received these vaccines, after the first and second doses. Therefore, the total immunoglobulin (Ig) levels specific to SARS-CoV-2 were measured using quantitative enzyme-linked immunosorbent assay (ELISA). The study population of 133 HCWs consisted of two groups in which the immune response was measured for the AZD1222 and BBV152 vaccines. Data collection was performed from 6 February to 20 August 2021. Four weeks after the first and second dose, the odds ratio of seroconversion for AZD1222 and BBV152 vaccine was 10.3 times (95% CI: 4.5-23.7) and 15.9 times (95% CI: 6.3-39.9), respectively. The GMT was 6392.93 and 6398.82 U/mL for AZD1222 and 1480.47 and 990.38 U/mL for BBV152 after the first and second doses, respectively. Both vaccines elicited an immune response, but the seroconversion rate and GMT after each dose were significantly higher for AZD1222 than those for the BBV152 vaccine in this study.

Comparison of two different volumes of 0.5%, ropivacaine used in ultrasound-guided adductor canal block after knee arthroplasty: A randomized, blinded, controlled noninferiority trial.

Background and Aims: The aim of this study was to establish noninferiority of 10 mL of 0.5% ropivacaine as compared to 20 mL of 0.5% ropivacaine; for choosing right dose in adductor canal block (ACB) after knee arthroplasty (KA), this trial was conducted. Material and Methods: Forty patients undergoing bilateral KA with postoperative ultrasound-aided ACB were randomized: Group A patients received 20 mL 0.5% ropivacaine in the right limb and 10 mL 0.5% ropivacaine in the left limb. Group B patients received 10 mL of 0.5% ropivacaine in the right limb and 20 mL of 0.5% ropivacaine in the left limb. Catheter is positioned for intermittent boluses every 12-h up to 48 h. Results: In the final analysis (excluding six patients) based on split-body design between Group I (comprising 34 limbs which received 20 mL of 0.5% ropivacaine) and Group II (comprising 34 limbs which received 10 mL of 0.5% ropivacaine), baseline demographic data were collected. Length of the limb from anterior superior iliac spine (ASIS) to the base of the patella was comparable between two groups: Group I (in cm; 149 ± 1.63) versus Group II (in cm; 149.5 ± 1.51) (P = 0.49, 95% CI of - 1.98 to 0.98). Primary outcomes, that is, quadriceps muscle strength, show a significant difference (P < 0.025) at various timeline. Secondary outcome pain scores and degree of knee flexion at various time intervals showed no significant difference. There was zero incidence of fall of the patient and no significant complication due to catheter was reported leading to discontinuation of catheter use in both groups. Conclusion: 10 mL of 0.5% ropivacaine is noninferior to 20 mL of 0.5% ropivacaine in providing postoperative analgesia with preserved quadriceps muscle strength.

Changes in reverse transcription polymerase chain reaction cycle threshold values of SARS-CoV-2 with topical povidone iodine use: A single-arm open-label interventional study.

Context: Repurposed povidone iodine (PVP-I) has been suggested as an effective adjuvant against coronavirus disease-2019 (COVID-19). Aim: The aim of this study was to assess the changes in RT-PCR cycle threshold (Ct) values of severe acute respiratory Syndrome Coronavirus-2 (SARS-CoV-2) genes with PVP-I intranasal and oral application. Settings and Design: A longitudinal (repeated measures) single-arm open-label interventional study was conducted for 200 samples of ten COVID-19 patients in South India. Methods and Material: Demographic and clinical information were collected. Intranasal application and oral gargle with 1% PVP-I solution was done four times a day for seven days. Nasopharyngeal and oropharyngeal samples were taken for RT-PCR test at hour-0, hour-2, hour-4 on Day-0, Day-3, Day-6, and hour-0 on Day-9. Methods and Material: STATA analysis software version 14.2 was used. McNemar Test was applied for paired samples. Skilling Mack Test was used to assess the association between PVP-I use (intra-day and inter-day) and E gene/N gene Ct values. Pearson correlation coefficients and Bland-Altman plots were used for further analyses. Results: Mean (SD) age of the patients was 41.5 (±8.82) years. A total of 100 pairs of nasopharyngeal and oropharyngeal samples were analysed. No significant difference was observed in the Ct values of asymptomatic and symptomatic patients. E gene Ct values (nasopharyngeal) at Hour-0 increased from Day-0 to Day-9 (P = 0.005). Ct value was higher at Hour-2 for most of the samples. Conclusions: RT-PCR results (qualitative) differed at various testing points in the same patients. Lower Ct values were found in the nasopharyngeal samples. Successive increase in E gene Ct values indicates reduced viral load with natural course of COVID-19. PVP-I may have an optimal impact within 2 h of usage. Clinical trial registration number: CTRI/2020/05/024962.

Low-Power Artificial Neural Network Perceptron Based on Monolayer MoS2.

Machine learning and signal processing on the edge are poised to influence our everyday lives with devices that will learn and infer from data generated by smart sensors and other devices for the Internet of Things. The next leap toward ubiquitous electronics requires increased energy efficiency of processors for specialized data-driven applications. Here, we show how an in-memory processor fabricated using a two-dimensional materials platform can potentially outperform its silicon counterparts in both standard and nontraditional Von Neumann architectures for artificial neural networks. We have fabricated a flash memory array with a two-dimensional channel using wafer-scale MoS2. Simulations and experiments show that the device can be scaled down to sub-micrometer channel length without any significant impact on its memory performance and that in simulation a reasonable memory window still exists at sub-50 nm channel lengths. Each device conductance in our circuit can be tuned with a 4-bit precision by closed-loop programming. Using our physical circuit, we demonstrate seven-segment digit display classification with a 91.5% accuracy with training performed ex situ and transferred from a host. Further simulations project that at a system level, the large memory arrays can perform AlexNet classification with an upper limit of 50 000 TOpS/W, potentially outperforming neural network integrated circuits based on double-poly CMOS technology.

Superconducting 2D NbS2 Grown Epitaxially by Chemical Vapor Deposition.

Metallic two-dimensional (2D) transition metal dichalcogenides (TMDCs) are attracting great attention because of their interesting low-temperature properties such as superconductivity, magnetism, and charge density waves (CDW). However, further studies and practical applications are being slowed down by difficulties in synthesizing high-quality materials with a large grain size and well-determined thickness. In this work, we demonstrate epitaxial chemical vapor deposition (CVD) growth of 2D NbS2 crystals on a sapphire substrate, with a thickness-dependent structural phase transition. NbS2 crystals are epitaxially aligned by the underlying c-plane sapphire resulting in high-quality growth. The thickness of NbS2 is well controlled by growth parameters to be between 1.5 and 10 nm with a large grain size of up to 500 µm. As the thickness increases, we observe in our NbS2 a transition from a metallic 3R-polytype to a superconducting 2H-polytype, confirmed by Raman spectroscopy, aberration-corrected scanning transmission electron microscopy (STEM) and electrical transport measurements. A Berezinskii-Kosterlitz-Thouless (BKT) superconducting transition occurs in the CVD-grown 2H-phase NbS2 below the transition temperature (Tc) of 3 K. Our work demonstrates thickness and phase-controllable synthesis of high-quality superconducting 2D NbS2, which is imperative for its practical applications in next-generation TMDC-based electrical devices.

Preparedness of medical students towards e-learning conducted during COVID-19 lockdown: A cross-sectional descriptive study.

BACKGROUND: COVID-19 lockdown has mandated the medical colleges to start academics using electronic mode. Synchronous e-learning was started by our institute to replicate traditional classes in line with the routine academic schedule. the objective of this study attempted to assess the e-learning readiness of the students of our institute. MATERIALS AND METHODS: A cross-sectional descriptive study was planned using the model proposed by Oketch et al. with local modifications. The questionnaire was designed in Google Forms and mailed to respond using Likert scale. The nonparametric data collected from the total 84 respondents were analyzed for validity and reliability of the questionnaire, mean values to know the readiness (mean = 3.4), and one-step multiple regression to know the predictors. RESULTS: The mean eLR (e-learning readiness) as evaluated from attitudinal readiness (MeanAR = 3.6), culture readiness (MeanCR = 2.3), material and technological readiness (MeanMTR = 3.7), and mental health readiness (MeanMHR = 2.4) is 3.03 (60.6% with n = 84). Multiple regression analysis revealed that all the variables except MHR can significantly predict e-learning readiness linearly (P < 0.05). CONCLUSION: The institute is ready for e-learning in terms of AR and MTR (mean values >3.4). CR and MHR still need a lot of improvisation to make it acceptable for e-learning. The model could explain 54.9% readiness level with CR as the most important predictor. More than 73% (n = 84) of the respondents have acknowledged the present form of online classes to be the best available option in COVID-19 lockdown and most of them are adapted to e-classes in the institute.