Theoretical investigation of quantum capacitance of Co-doped α-MnO2 for supercapacitor applications using density functional theory

The rapid depletion of fossil fuels and ever-growing energy demand have led to a search for renewable clean energy sources. The storage of renewable energy calls for immediate attention to the fabrication of efficient energy storage devices like supercapacitors (SCs). As an electrode material for SCs, MnO2 has gained wide research interest because of its high theoretical capacitance, variable oxidation state, vast abundance, and low cost. However, the low electric conductivity of MnO2 limits its practical application. The conductivity of MnO2 can be enhanced by tuning the electronic states through substitution doping with cobalt. In the present work, first principles analysis based on density functional theory (DFT) has been used to examine the quantum capacitance (CQC) and surface charge (Q) of Co-doped MnO2. Doping enhanced the structural stability, electrical conductivity, potential window, and quantum capacitance of α-MnO2. The shortened band gap and localized states near the Fermi level improve the CQC of α-MnO2. For the narrow potential range (-0.4 to 0.4 V), the CQC is observed to increase with doping concentration. The highest CQC value at +0.4 V is observed to be 2412.59 μF cm-2 for Mn6Co2O16 (25% doping), five times higher than that of pristine MnO2 (471.18 μF cm-2). Mn6Co2O16 also exhibits better CQC and 'Q' at higher positive bias. Hence, it can be used as an anode material for asymmetric supercapacitors. All these results suggest better capacitive performance of Co-doped α-MnO2 for aqueous SCs and as an anode material for asymmetric supercapacitors.

A Critical Review on Orthosilicate Li2MSiO4 (M= Fe, Mn) Electrode Materials for Li Ion Batteries

The development of novel electrode materials with good electrochemical performances is necessary for the expanded and varied applications of lithium-ion batteries, and this development heavily relies on cathode materials. Due to excellent thermal stability, abundance, low cost, and environmental friendliness, orthosilicate cathode materials Li2MSiO4 (M= Fe, Mn) has received a lot of attention recently. The present review article gives a glimpse into the characteristics, advantages, and recent progress of orthosilicate cathode materials. This review starts with a brief history and working mechanism of batteries, the advantages of cathode materials followed by types of cathode materials, various synthesis methods, and different techniques used for their characterization. The most current initiatives to enhance orthosilicate Li2MSiO4 type electrochemical performances were introduced in this review. We provide a critical assessment of the efficient modification techniques for the orthosilicate Li2MSiO4 type cathode materials in particular. These potential cathode materials' synthesis, structure, morphologies, and particularly electrochemical performances have been thoroughly examined. This evaluation, we hope, will clarify the sustained advancement of high-efficiency and reasonably priced Li-ion batteries&#xD.

Transition metal dichalcogenide (TMDs) electrodes for supercapacitors: a comprehensive review

As globally, the main focus of the researchers is to develop novel electrode materials that exhibit high energy and power density for efficient performance energy storage devices. This review covers the up-to-date progress achieved in transition metal dichalcogenides (TMDs) (e.g. MoS₂, WS₂, MoSe_2,and WSe₂) as electrode material for supercapacitors (SCs). The TMDs have remarkable properties like large surface area, high electrical conductivity with variable oxidation states. These properties enable the TMDs as the most promising candidates to store electrical energy via hybrid charge storage mechanisms. Consequently, this review article provides a detailed study of TMDs structure, properties, and evolution. The characteristics technique and electrochemical performances of all the efficient TMDs are highlighted meticulously. In brief, the present review article shines a light on the structural and electrochemical properties of TMD electrodes. Furthermore, the latest fabricated TMDs based symmetric/asymmetric SCs have also been reported.

Structural, electrical properties and dielectric relaxations in Na+-ion-conducting solid polymer electrolyte

In this paper, we have studied the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium-ion-conducting solid polymer electrolyte film comprising PEO₈-NaPF₆+  x wt. % succinonitrile. The structural and surface morphology properties have been investigated, respectively using x-ray diffraction and field emission scanning electron microscopy. The complex formation was examined using Fourier transform infrared spectroscopy, and the fraction of free anions/ion pairs obtained via deconvolution. The complex dielectric permittivity and loss tangent has been analyzed across the whole frequency window, and enables us to estimate the DC conductivity, dielectric strength, double layer capacitance and relaxation time. The presence of relaxing dipoles was determined by the addition of succinonitrile (wt./wt.) and the peak shift towards high frequency indicates the decrease of relaxation time. Further, relations among various relaxation times ([Formula: see text]) have been elucidated. The complex conductivity has been examined across the whole frequency window; it obeys the Universal Power Law, and displays strong dependency on succinonitrile content. The sigma representation ([Formula: see text]) was introduced in order to explore the ion dynamics by highlighting the dispersion region in the Cole-Cole plot ([Formula: see text]) in the lower frequency window; increase in the semicircle radius indicates a decrease of relaxation time. This observation is accompanied by enhancement in ionic conductivity and faster ion transport. A convincing, logical scheme to justify the experimental data has been proposed.

Burden of bacterial upper respiratory tract pathogens in school children of Nepal

INTRODUCTION

Respiratory tract infections are one of the most common human infections in all age group and important cause of mortality and morbidity worldwide. Most bacterial upper respiratory tract infections are vaccine preventable. This study aimed to determine the prevalence of carrier state of bacterial upper respiratory tract pathogens among school children. It also aimed to study their antibiograms.

METHODS

The specimen from posterior pharyngeal wall and tonsils were collected from 204 participants on calcium alginate coated swabs (HiMedia). Isolates were identified by standard microbiological methods and tested for in vitro antibiotic susceptibility testing by modified Kirby-Bauer disc diffusion method.

RESULTS

In this study, Streptococcus pneumoniae (16.6%) was the most common bacterial pathogen recovered, followed by Staphylococcus aureus (14.7%), β-haemolytic streptococci (non-Group A) (8.8%), Streptococcus pyogenes (5.3%) and Corynebacterium diphtheriae (3.4%). The Gram negative bacteria were Klebsiella pneumoniae (4.9%), Haemophilus influenzae (3.4%) and Neisseria meningitidis (1.4%). Important findings in antibiogram include high resistance of Streptococcus pneumoniae to penicillin (91.17%) and resistance of S. aureus to oxacillin (23.3%).

CONCLUSION

Pharyngeal colonisation by S. pneumoniae was found high among school children and this calls for an urgent need to include pneumococcal vaccine in routine national immunisation schedule of Nepal given the high burden of invasive pneumococcal disease. Despite expected universal vaccination, pharyngeal colonisation by C. diphtheriae is possible and there is possibility of transmission of these respiratory pathogens to other healthy children.

ESTIMATES OF EX-SERVICEMEN POPULATION FOR NEXT 30 YEARS: A NEED TO REORIENT OUR HEALTH PLANNING

A mathematical model, using survival analysis methods has been developed to estimate the total population as well as the populations as per specific age groups of ex-servicemen for the next 30 years. The results indicate that from the present population of 13.75 lakhs., the total population of ex-servicemen would be 15.62 lakhs by 2027 A.D. In addition, there are likely to be noteworthy changes in the population structure. While the population of geriatric age group (65 years and above) is only 21% at present compared to 49% from age group 45-54 years, by 2027 A.D. the geriatric age group would contribute to 34% of the ex-servicemen population while 45-54 years age group would constitute only 36%. There is a need, therefore, to start rethinking on our future plans as regards health services since geriatric health problems are likely to become a leading health issue after the next ten years.

Profile of management of animal bite cases among rural population in district Pune, Maharashtra

The study was carried out in three randomly selected Primary Health Centres (PHCs) of district Pune. During three months of study period all the patients with animal bite attending PHCs were enrolled for the study. All the animal bite cases (451) were due to dog bite and 61.4% were reported to be bitten by pet dogs. In spite of having the knowledge about seriousness of illness, immediate care like washing of wound with soap and water was practiced by only 23.5%. Majority of them did not report immediately to PHC for treatment after dog bite.

Saw palmetto berry extract inhibits cell growth and Cox-2 expression in prostatic cancer cells

The cytotoxicity of a commonly used material to alleviate the symptoms of benign prostatic hyperplasia (BPH), Saw Palmetto Berry Extract (SPBE), was examined as neat oil using a set of prostatic cell lines; 267B-1, BRFF-41T and LNCaP. Proliferation of these prostatic derived cell lines is inhibited to different degrees when dosed for 3 days with SPBE. The amount of SPBE required to inhibit 50% growth (IC50) of these cell lines was 20-30 nl equivalents of SPBE per ml of medium for cell lines 267B-1 and BRFF-41T and approximately 10-fold more for the LNCaP cell line. The effect of SPBE dosing on these cell lines is not irreversible, since a 30 min treatment with SPBE at an IC50 concentration does not inhibit their growth. Normal prostate cells were inhibited by 20-25% when grown in the presence of 200 nl SPBE equivalent per ml media. Growth of other non-prostatic cancer cell lines, i.e. Jurkat and HT-29, was affected by approx. 50% and 40%, respectively. When LNCaP cells were grown in the presence of dihydrotestosterone and SPBE, the IC50 concentration decreased significantly compared to LNCaP cells grown in the presence of serum and SPBE. Reduced cellular growth after SPBE treatment of these cell lines may relate to decreased expression of Cox-2 and may be due to changes observed in the expression of Bcl-2. Expression of Cox-1 under similar conditions is not affected because of its constitutive expression. Since increased Cox-2 expression is associated with an increased incidence of prostate cancer, and decrease in its expression by SPBE would provide a basis for further investigation of its use against BPH and in prostatic cancer chemoprevention.

Synthesis and characterization of fluoro-substituted polyaniline

Poly(2-fluoroaniline) was prepared by both chemical and electrochemical polymerization in acidic medium. Characterization of poly(2-fluoroaniline) was accomplished experimentally using ultraviolet-visible, Fourier transform infrared, differential scanning calorimetry, thermal gravimetric analysis, and X-ray diffraction techniques, respectively. Scanning electron microscopy studies revealed globular morphology of chemically synthesized poly(2-fluoroaniline). The cyclic voltammetric studies revealed diffusion-controlled phenomenon in electrochemically synthesized poly(2-fluoroaniline).

EPIDEMIOLOGICAL STUDY OF ENTEROPATHOGENIC CARRIER STATE AMONG FOOD HANDLERS OF ARMED FORCES EATING ESTABLISHMENTS

A cross-sectional epidemiological study was undertaken on a randomly selected sample of 308 food handlers working in different eating establishments of Indian Armed Forces in Pune. These included 101 Service personnel and 207 civilians. Stool samples were analysed for enteropathogens and epidemiological assessment of gastrointestinal disease occurrence in the military units of these food handlers was undertaken. The study revealed that 4 of the subjects were carriers of salmonella typhimurium, thus giving the prevalence as 1.3% (95% confidence interval 0.2% to 2.56%). No other enteropathogen except salmonella typhimurium was isolated. The positive carriers showed a typical "spatial - clustering" in that they were working in two geographically contiguous medical units.