Stable Efficient Solid-State Supercapacitors and Dye-Sensitized Solar Cells Using Ionic Liquid-Doped Solid Biopolymer Electrolyte.

As synthetic and nonbiodegradable compounds are becoming a great challenge for the environment, developing polymer electrolytes using naturally occurring biodegradable polymers has drawn considerable research interest to replace traditional aqueous electrolytes and synthetic polymer-based polymer electrolytes. This study shows the development of a highly conducting ionic liquid (1-hexyl-3-methylimidazolium iodide)-doped corn starch-based polymer electrolyte. A simple solution cast method is used to prepare biopolymer-based polymer electrolytes and characterized using different electrical, structural, and photoelectrochemical studies. Prepared polymer electrolytes are optimized based on ionic conductivity, which shows an ionic conductivity as high as 1.90 × 10-3 S/cm. Fourier transform infrared spectroscopy (FTIR) confirms the complexation and composite nature, while X-ray diffraction (XRD) and polarized optical microscopy (POM) affirm the reduction of crystallinity in biopolymer electrolytes after doping with ionic liquid (IL). Thermal and photoelectrochemical studies further affirm that synthesized material is well stable above 200 °C and shows a wide electrochemical window of 3.91 V. The ionic transference number measurement (t ion) confirms the predominance of ionic charge carriers in the present system. An electric double-layer capacitor (EDLC) and a dye-sensitized solar cell (DSSC) were fabricated by using the highest conducting corn starch polymer electrolyte. The fabricated EDLC and DSSC delivered an average specific capacitance of 130 F/g and an efficiency of 1.73% in one sun condition, respectively.

Stable and Efficient Dye-Sensitized Solar Cells and Supercapacitors Developed Using Ionic-Liquid-Doped Biopolymer Electrolytes.

An ionic liquid (IL) 1-ethyl, 2-methyl imidazolium thiocyanate incorporated biopolymer system is reported in this communication for applications in dual energy devices, i.e., electric double-layer capacitors (EDLCs) and dye-sensitized solar cells (DSSCs). The solution caste method has been used to synthesize ionic-liquid-incorporated biopolymer electrolyte films. The IL mixed biopolymer electrolytes achieve high ionic conductivity up to the order of 10-3 S/cm with good thermal stability above 250 °C. Electrical, structural, and optical studies of these IL-doped biopolymer electrolyte films are presented in detail. The performance of EDLCs was evaluated using low-frequency electrochemical impedance spectroscopy, cyclic voltammetry, and constant current charge-discharge, while that of DSSCs was assessed using J-V characteristics. The EDLC cells exhibited a high specific capacitance of 200 F/gram, while DSSCs delivered 1.53% efficiency under sun conditions.

The Impact of Polymer Electrolyte Properties on Lithium-Ion Batteries.

In recent decades, the enhancement of the properties of electrolytes and electrodes resulted in the development of efficient electrochemical energy storage devices. We herein reported the impact of the different polymer electrolytes in terms of physicochemical, thermal, electrical, and mechanical properties of lithium-ion batteries (LIBs). Since LIBs use many groups of electrolytes, such as liquid electrolytes, quasi-solid electrolytes, and solid electrolytes, the efficiency of the full device relies on the type of electrolyte used. A good electrolyte is the one that, when used in Li-ion batteries, exhibits high Li+ diffusion between electrodes, the lowest resistance during cycling at the interfaces, a high capacity of retention, a very good cycle-life, high thermal stability, high specific capacitance, and high energy density. The impact of various polymer electrolytes and their components has been reported in this work, which helps to understand their effect on battery performance. Although, single-electrolyte material cannot be sufficient to fulfill the requirements of a good LIB. This review is aimed to lead toward an appropriate choice of polymer electrolyte for LIBs.

Graphene nanosheets derived from plastic waste for the application of DSSCs and supercapacitors.

The present study reports the upcycling process of waste plastics into value-added product graphene nanosheets (GNs) and their subsequent applications in dye sensitized solar cells (DSSCs) and supercapacitors. Bentonite nanoclay has been used as an agent for the degradation of waste plastics with two step pyrolysis processes at 450 °C and 945 °C in an inert atmosphere of N2 gas to obtain GNs. The GNs with few layers were confirmed by the RAMAN spectroscopy, XRD and HRTEM analyses. Further, FT-IR and EDX analyses also performed for the identification and quantitative analysis of functional groups in GNs. The GNs thus synthesized from plastic waste have been used for the fabrication of DSSCs and supercapacitors. The DSSC fabrication with GNs as part of photo-anode with polymeric electrolyte showed a high fill factor of 86.4% and high Voc of 0.77 V, which were also supported by the computational findings. On the other hand, the utilization of GNs as an active layer material of supercapacitor electrodes offered a high specific capacitance of 398 F/g with a scan rate of 0.005 V/s. The supercapacitor also exhibited significant energy density (Ed) and power density (Pd) of 38 Wh/kg and 1009.74 W/kg, respectively. Thus, the process illustrated the utility of waste plastics upcycling for conservation of EEE i.e., ecology, economy and energy for better tomorrow.

Participatory modelling for poverty alleviation using fuzzy cognitive maps and OWA learning aggregation.

Participatory modelling is an emerging approach in the decision-making process through which stakeholders contribute to the representation of the perceived causal linkages of a complex system. The use of fuzzy cognitive maps (FCMs) for participatory modelling helps policy-makers develop dynamic quantitative models for strategising development interventions. The aggregation of knowledge from multiple stakeholders provides consolidated and more reliable results. Average aggregation is the most common aggregation method used in FCMs-based modelling for weighted interconnections between concepts. This paper proposes a new aggregation method using learning OWA (ordered weighted averaging) operators for aggregating FCM weights assigned by various stakeholders. Besides, we report a comparative analysis of 'OWA learning aggregation' with the conventional average aggregation method, while evaluating the theory of change for the world's most extensive poverty alleviation programme in India. The results of the FCMWizard web-based tool show that the proposed method provides an opportunity to policy-makers for evaluating outcomes of proposed policies while addressing social resilience and economic mobility.

Evaluating poverty alleviation strategies in a developing country.

A slew of participatory and community-demand-driven approaches have emerged in order to address the multi-dimensional nature of poverty in developing nations. The present study identifies critical factors responsible for poverty alleviation in India with the aid of fuzzy cognitive maps (FCMs) deployed for showcasing causal reasoning. It is through FCM-based simulations that the study evaluates the efficacy of existing poverty alleviation approaches, including community organisation based micro-financing, capability and social security, market-based and good governance. Our findings confirm, to some degree, the complementarity of various approaches to poverty alleviation that need to be implemented simultaneously for a comprehensive poverty alleviation drive. FCM-based simulations underscore the need for applying an integrated and multi-dimensional approach incorporating elements of various approaches for eradicating poverty, which happens to be a multi-dimensional phenomenon. Besides, the study offers policy implications for the design, management, and implementation of poverty eradication programmes. On the methodological front, the study enriches FCM literature in the areas of knowledge capture, sample adequacy, and robustness of the dynamic system model.

An Ultra-Simple Method for Synthesis of Violet CdS Quantum Dots at Sub-Room Temperature.

The emergence of fluorescence quantum dots (QDs) has led to the development of variety of applications in science and technology. Owing to the diverse optical and electrical properties of CdS QDs we have synthesized the same using wet chemical method. The QDs have been prepared at sub-room temperature using a new solvent comprising a mixture of water and methanol. The QDs when seen under UV light radiate violet color. The band-gap of the QDs deduced from the absorption spectra was 3.08 eV while PL spectra of the QDs suggested possibility of multiple exciton generation with a close to narrow size distribution. XRD analysis confirmed cubic structure of the particles. The obtained results suggest that these QDs can play ideal role in quantum dot sensitized solar cells (QDSSC) or in light emitting diodes (LEDs).

Biogenic synthesis and thermo-magnetic study of highly porous carbon nanotubes.

Nanomaterials synthesis using natural sources is the technology to up come with advanced materials through extracts of plant, microorganisms, poultry waste etc. In this study, the authors report the synthesis of porous carbon nanotubes using high-temperature decomposition technique facilitated by cobalt salt using chicken fats, a poultry waste as a precursor. Since chicken fats contain fatty acids which can decompose into short hydrocarbon chains and cobalt can act as the catalyst. The formation of carbon nanotubes was confirmed by Raman spectra, peaks at 1580 and 1350.46 cm-1 confirmed the graphite mode G-band and structural imperfections defect mode D-band, respectively. Transmission electron microscopy showed the formation of tube-like structures. Nitrogen adsorption-desorption studies showed the high-surface area of 418.1 m2g-1 with an estimated pore diameter of 8.1 nm. Thermogravimetry analysis-derivative thermogravimetric analysis-differential thermal analysis showed the instant weight loss at 517°C attributed to the rapid combustion of nanotubes. A vibrating-sample magnetometer showed the paramagnetic nature of the so-formed carbon nanotubes formed.

Visible upconversion in Er3+/Yb3+ co-doped LaAlO3 phosphors.

The Er3+ doped and Er3+/Yb3+ co-doped LaAlO3 phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb3+ ions into Er3+:LaAlO3, the blue, green and red upconversion emissions of Er3+ ions have been enhanced about ~20, ~54 and ~22 times, under 978nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er3+:LaAlO3, whereas energy transfer is dominant mechanism in Er3+/Yb3+:LaAlO3 phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb3+ ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.

Three dimensional graphene transistor for ultra-sensitive pH sensing directly in biological media.

In this work, pH sensing directly in biological media using three dimensional liquid gated graphene transistors is presented. The sensor is made of suspended network of graphene coated all around with thin layer of hafnium oxide (HfO2), showing high sensitivity and sensing beyond the Debye-screening limit. The performance of the pH sensor is validated by measuring the pH of isotonic buffered, Dulbecco's phosphate buffered saline (DPBS) solution, and of blood serum derived from Sprague-Dawley rat. The pH sensor shows high sensitivity of 71 ± 7 mV/pH even in high ionic strength media with molarities as high as 289 ± 1 mM. High sensitivity of this device is owing to suspension of three dimensional graphene in electrolyte which provides all around liquid gating of graphene, leading to higher electrostatic coupling efficiency of electrolyte to the channel and higher gating control of transistor channel by ions in the electrolyte. Coating graphene with hafnium oxide film (HfO2) provides binding sites for hydrogen ions, which results in higher sensitivity and sensing beyond the Debye-screening limit. The 3D graphene transistor offers the possibility of real-time pH measurement in biological media without the need for desaltation or sample preparation.

Acute Respiratory Distress Syndrome: A Rare Complication in Pediatric Diabetic Ketoacidosis.

Cerebral edema (CE) and non cardiogenic pulmonary edema (acute respiratory distress syndrome, ARDS) are life-threatening complications of diabetic ketoacidosis (DKA). In contrast to CE complicating DKA, which is primarily reported in pediatric patients, ARDS is rarely described in this age group. Here, the authors present a child with DKA who developed both cerebral edema and ARDS during the course of her management. It is feasible that severe acidosis, hypotension, azotemia, hypoalbuminemia and the superimposed aggressive intravenous fluid administration were important risk factors for the development of cerebral edema and ARDS in the index patient. The report highlights the importance of early diagnosis and aggressive therapy in the management of ARDS, and summarizes the published literature on this rarely reported complication of pediatric DKA.

RD-1 encoded EspJ protein gets phosphorylated prior to affect the growth and intracellular survival of mycobacteria.

Mycobacterium tuberculosis (MTB) synchronizes a number of processes and controls a series of events to subvert host defense mechanisms for the sake of residing inside macrophages. Besides these, MTB also possesses a wide range of signal enzyme systems, including eleven serine threonine protein kinases (STPKs). The present study describes STPK modulated modification in one of the hypothetical proteins of the RD1 region; EspJ (ESX-1 secretion associated protein), which is predicted to be involved in virulence of MTB. We have employed knock-out MTB, and M. bovis BCG as a surrogate strain to elaborate the consequence of the phosphorylation of EspJ. The molecular and mass spectrometric analyses in this study, confirmed EspJ as one of the substrates of STPKs. The ectopic expression of phosphoablative mutants of espJ in M. bovis BCG also articulated the effect of phosphorylation on the growth and in survival of mycobacteria. Importantly, the level of phosphorylation of EspJ also differed between pathogenic H37 Rv (Rv) and non pathogenic H37 Ra (Ra) strains of MTB. This further suggested that to a certain extent, the STPKs mediated phosphorylation may be accountable, in determining the growth and in intra-cellular survival of mycobacteria.

Biochemical and functional characterizations of tyrosine phosphatases from pathogenic and nonpathogenic mycobacteria: indication of phenyl cyclopropyl methyl-/phenyl butenyl azoles as tyrosine phosphatase inhibitors.

Tyrosine phosphorylation is one of the most common means of posttranslational modifications which can generate novel recognition motifs for protein interactions and thereafter affecting cellular localization, protein stability, and enzyme activity. Mycobacterium tuberculosis (Mtb) possesses a wide range of signal transduction systems, including two protein tyrosine phosphatases (PtpA and PtpB). Since functional diversities between protein tyrosine phosphatases (PTPases) are illustrated by regulatory domains and subunits, we have characterized the nature of tyrosine phosphatases from slow-grower pathogenic species Mtb and from fast-grower nonpathogenic species Mycobacterium smegmatis (MS). The findings delineate that the enzymes present in MS have significantly lesser phosphatase activity than PTPases of Mtb as evidenced by low K cat/K m of recombinantly expressed proteins. The K cat/K m for Mtb PtpA was 500-1000-fold higher than MS PTPases. We have designed and synthesized phenyl cyclopropyl methyl-/phenyl butenyl azoles which inhibit growth of mycobacteria, in culture and in macrophages. The mechanism of efficacy of these compounds against mycobacteria was identified and suggested that the inhibition may possibly be mediated via the targeting of Mtb tyrosine phosphatase. The results further added that these compounds exclusively inhibit PtpA of Mtb.

Effect of variation of average pore size and specific surface area of ZnO electrode (WE) on efficiency of dye-sensitized solar cells.

Mesoporous ZnO nanoparticles have been synthesized with tremendous increase in specific surface area of up to 578 m(2)/g which was 5.54 m(2)/g in previous reports (J. Phys. Chem. C 113:14676-14680, 2009). Different mesoporous ZnO nanoparticles with average pore sizes ranging from 7.22 to 13.43 nm and specific surface area ranging from 50.41 to 578 m(2)/g were prepared through the sol-gel method via a simple evaporation-induced self-assembly process. The hydrolysis rate of zinc acetate was varied using different concentrations of sodium hydroxide. Morphology, crystallinity, porosity, and J-V characteristics of the materials have been studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), BET nitrogen adsorption/desorption, and Keithley instruments.

Metamaterials for remote generation of spatially controllable two dimensional array of microplasma.

Since the initial demonstration of negative refraction and cloaking using metamaterials, there has been enormous interest and progress in making practical devices based on metamaterials such as electrically small antennas, absorbers, modulators, detectors etc that span over a wide range of electromagnetic spectrum covering microwave, terahertz, infrared (IR) and optical wavelengths. We present metamaterial as an active substrate where each unit cell serves as an element for generation of plasma, the fourth state of matter. Sub-wavelength localization of incident electromagnetic wave energy, one of the most interesting properties of metamaterials is employed here for generating high electric field to ignite and sustain microscale plasmas. Frequency selective nature of the metamaterial unit cells make it possible to generate spatially localized microplasma in a large array using multiple resonators. A dual resonator topology is shown for the demonstration. Since microwave energy couples to the metamaterial through free space, the proposed approach is naturally wireless. Such spatially controllable microplasma arrays provide a fundamentally new material system for future investigations in novel applications, e.g. nonlinear metamaterials.

Phosphorylation of pyruvate kinase A by protein kinase J leads to the altered growth and differential rate of intracellular survival of mycobacteria.

PknJ (Rv2088) is a serine/threonine protein kinase of mycobacteria which is present in Mycobacterium tuberculosis (MTB), but its gene is absent in Mycobacterium smegmatis (MS); a fast grower and nonpathogenic species of mycobacteria. The heterologous expression of MTB-specific PknJ in MS altered the growth of recombinant mycobacteria highlighting one of the characteristics of this protein. This nature of the protein was further confirmed when Mycobacterium bovis BCG (BCG) containing antisense copy of pknJ resulted in the increased growth of BCG. The real-time RNA quantification analysis pointed out toward increased expression of this protein during infection of THP-1 macrophage cells which further emphasized that the protein is essential for the intracellular survival of mycobacteria. The differential in gel electrophoresis (DIGE) data followed by mass spectroscopy suggested that PknJ is involved in regulation of pyruvate kinase A (Rv1617). Since pyruvate kinase (PK) A is one of the key enzymes which controls glycolytic cycle in mycobacteria, we looked for its interaction with PknJ during extracellular and intracellular growth of mycobacteria. In order to identify the specific residue(s) involved in post-translational modification, the phospho-null mutants of PK were generated, and their substrate specificities in response to PknJ were assessed through kinase assay. The findings thus underlined that the PK activity is predominantly dependent on the threonine residue at the 94(th) position and further suggested that this site may be plausible in intracellular survival of mycobacteria upon phosphorylation with PknJ.

All electronic approach for high-throughput cell trapping and lysis with electrical impedance monitoring.

We present a portable lab-on-chip device for high-throughput trapping and lysis of single cells with in-situ impedance monitoring in an all-electronic approach. The lab-on-chip device consists of microwell arrays between transparent conducting electrodes within a microfluidic channel to deliver and extract cells using alternating current (AC) dielectrophoresis. Cells are lysed with high efficiency using direct current (DC) electric fields between the electrodes. Results are presented for trapping and lysis of human red blood cells. Impedance spectroscopy is used to estimate the percentage of filled wells with cells and to monitor lysis. The results show impedance between electrodes decreases with increase in the percentage of filled wells with cells and drops to a minimum after lysis. Impedance monitoring provides a reasonably accurate measurement of cell trapping and lysis. Utilizing an all-electronic approach eliminates the need for bulky optical components and cameras for monitoring.

Putative roles of a proline-glutamic acid-rich protein (PE3) in intracellular survival and as a candidate for subunit vaccine against Mycobacterium tuberculosis.

The proline-glutamic acid (PE) protein family of Mycobacterium tuberculosis (Mtb) plays diverse roles in the pathogenesis and modulation of host immune responses. The uniqueness of conserved regions of PE proteins may be useful to test and validate their corresponding functions. Hence, the present study has been undertaken to demonstrate the role of PE3 (Rv0159c) for persistence, host immune response and immunoprophylaxis. We have expressed Mtb-specific PE3 gene in M. smegmatis (MS) and used the strain to infect J774A.1 macrophage cells and BALB/c mice. It was observed that during the infection, the MS expressing PE3 showed higher bacterial load when compared to infection with wild-type MS. In hypoxic condition, the expression level of PE3 gene was induced in Mtb, which further showed its relevance in the cell survival during hypoxia-induced persistence. The expression level of PE3 in Mtb was markedly induced during chronic stage of murine infection, which reiterated its importance in mycobacterial persistence in the host. The immunization of mice with recombinant PE3 protein stimulated the secretion of TNF, IL-6 and IL-2 cytokines and generated strong protective immunity against challenge with live mycobacteria, which was evidenced by decreased viable bacilli in the lungs, histopathological changes and increased survival of PE3 immunized mice. Conclusively, the results indicated that PE3 plays significant roles in mycobacterial persistence during infection, modulate host immune response and hence could be a prospective candidate for the development of subunit vaccine against tuberculosis.

Protective and survival efficacies of Rv0160c protein in murine model of Mycobacterium tuberculosis.

The proline-glutamic acid (PE) and proline-proline-glutamic acid (PPE) multi-gene families code for approximately 10% of the Mycobacterium tuberculosis (Mtb) genome. These proteins are thought to be virulence factors that participate in impounding the host immune responses. While some members have been studied, the functions of most PE/PPE proteins are yet to be explored. The studies presented here have specifically characterized the roles of one of the PE proteins of Mtb, Rv0160c (PE4), in mycobacterial persistence and in prophylactic efficacy. We have expressed Rv0160c in a non-pathogenic fast-growing Mycobacterium smegmatis strain and demonstrated that the protein improves the survival of mycobacteria in macrophages and in mice. The protein has also shown its effect under physiological stress of bacteria, as evidenced by elevated expression in acidic and in hypoxic conditions. In mice, the level of Rv0160c was noticeably high during the chronic stage of tuberculosis. The seroreactivity of the protein against different categories of tuberculosis patients revealed a strong B-cell humoral response in freshly infected pulmonary tuberculosis patients. In mice, it exhibited increased IL-2, TNF, and IL-6 production. The antigenic properties of the protein directed towards the protective efficacy against the Mtb challenge. All together, our findings have identified Rv0160c as an in vivo expressed immunodominant antigen which plays a crucial role in the pathogenesis of mycobacterial disease and could prove to be a good preventive antigen for tuberculosis.

Novel biopolymer gel electrolyte for dye-sensitized solar cell application.

We report a new biopolymer electrolyte for dye sensitized solar cell application. To develop polymer electrolyte, potassium iodide have been added in agarose biopolymer matrix and characterized using various techniques like complex impedance spectroscopy, Infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM). Complex impedance spectroscopy shows many folds enhancement in ionic conductivity (σ) by salt doping and conductivity maxima was obtained near 60:40 composition. Infrared spectroscopy confirms the formation of composite nature. XRD revels the reduction of crystallinity by salt doping as well affirms the composite nature. Scanning electron microscopy (SEM) shows reduction in crystallinity of gel matrix by salt doping which is a known favorable condition for ionic conductivity enhancement. To further affirm the conductivity enhancement in the gel electrolyte system a theoretical hopping model is also described in details. A DSSC has been developed using maximum electrical conductivity film which shows 0.54% efficiency at 1 sun condition.