Graphene-Doped Hydrogels Promoting Ionic Conductivity in Gel-Valve-Regulated Lead Acid Batteries.

In this study, the impact of graphene-doped poly(vinyl alcohol) hydrogels on gel-valve-regulated lead acid batteries was examined. The gel formulations were made by adding various amounts of graphene into the gel system comprising poly(vinyl alcohol) and sulfuric acid. Gel formulations were subjected to an ionic conductivity study and Fourier transform infrared spectroscopy (FTIR) to understand ionic mobility and material interaction, respectively. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) were utilized to find the optimized amount of graphene in gel formulations. Galvanostatic charge-discharge (GCD) techniques were employed on a battery comprising an optimized gel electrolyte. The battery exhibited a discharge capacity of 12.82 mAh at a current density of 15 mA cm-2. After 500 prolonged cycles, the battery displayed a discharge capacity of 87% at 25 mA cm-2 current density, indicating that graphene-doped hydrogels can be a promising gel electrolyte for lead acid batteries.

Studies on Evaluation of the Thermal Conductivity of Alumina Titania Hybrid Suspension Nanofluids for Enhanced Heat Transfer Applications.

Extensive investigations were made and empirical relations were proposed for the thermal conductivity of mono-nanofluids. The effect of concentration, diameter, and thermal properties of participating nanoparticles is missing in the majority of existing thermal conductivity models. An attempt is made to propose a model that considers the influence of such missing parameters on the thermal conductivity of hybrid nanofluids. Al2O3-TiO2 hybrid nanofluids have a 0.1% particle volume concentration prepared with distinct particle volume ratios (k - 1:6 - k, k = 1 to 6) in DI water. The samples were characterized, and the size and shape of the nanoparticles were verified. Also, the influence of varying particle volume ratios and the fluid temperature (varying from 283 to 308 K) were examined. 2.4 and 2.1% enhancements were observed in the thermal conductivity of alumina (5:0) and titania (0:5) nanofluids (having 0.1% volume concentration), respectively. Due to the low thermal conductivity of titania nanoparticles, the conductivity of the hybrid solution is above that of titania and below that of alumina nanofluids. An empirical relation for the thermal conductivity of hybrid nanofluids is established and validated considering the individual particle size, volume ratio, and thermal conductivity of particles.

Fabrication of Flexible Films for Supercapacitors Using Halloysite Nano-Clay Incorporated Poly(lactic acid).

In the past few years, significant research efforts have been directed toward improving the electrochemical capabilities of supercapacitors by advancing electrode materials. The present work signifies the development of poly(lactic acid)/alloysite nano-clay as an electrode material for supercapacitors. Physico-chemical characterizations were analyzed by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and a universal testing machine. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge techniques were employed to evaluate electrochemical characteristics. The optimized poly(lactic acid)/halloysite nano-clay film revealed the highest specific capacitance of 205.5 F g-1 at 0.05 A g-1 current density and showed 14.6 Wh kg-1 energy density at 72 W kg-1 power density. Capacitance retention of 98.48% was achieved after 1000 cycles. The microsupercapacitor device presented a specific capacitance of 197.7 mF g-1 at a current density of 0.45 mA g-1 with 10.8 mWh kg-1 energy density at 549 mW kg-1 power density.

Nanobacterial Cellulose Production and Its Antibacterial Activity in Biodegradable Poly(vinyl alcohol) Membranes for Food Packaging Applications.

Nanobacterial cellulose (NBC) was produced and incorporated into biodegradable poly(vinyl alcohol) (PVA) in different weight ratios to obtain polymer nanocomposite membranes. The physicochemical properties of the membranes were studied using Fourier transform infrared (FTIR) spectroscopy, a universal testing machine (UTM), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD) techniques, and field emission scanning electron microscopy (FESEM). FTIR confirmed the consolidation of NBC into PVA by exhibiting significant changes in the peaks compared to NBC and PVA individually. The highest tensile strength of 53.33 MPa and 235.30% elongation at break of the membrane M-10 mass % NBC was obtained, illuminating that NBC provides stiffness and PVA imparts elasticity. WAXD revealed that the crystalline nature of the membrane increases up to 10 mass % and decreases beyond it. The effect of NBC on the poly(vinyl alcohol) membranes for food packaging was investigated systematically. Among all the membranes, M-10 mass % NBC was found to be the most suitable for packaging applications. Membranes had antimicrobial activity against food microbes and showed degradability behavior in the soil. The tests on membranes for packaging revealed that fruits were protected from spoilage caused by microorganisms. Hence, the prepared membranes could be used as an alternative to conventional plastics for packaging applications.

A Novel Poly(vinyl alcohol)-tetraethylorthosilicate Hybrid Gel Electrolyte for Lead Storage Battery.

The gel electrolyte significantly influences gel valve-regulated lead acid battery performance. To address this, the paper describes the preparation of novel polymer gel electrolytes using poly (vinyl alcohol) (PVA) and tetraethylorthosilicate (TEOS) for valve-regulated lead-acid batteries. FTIR technique is used to confirm the chemical reaction between PVA and TEOS. Electrochemical analyses such as cyclic voltammetry and electrochemical impedance spectroscopy were applied to optimize the concentration of PVA-TEOS polymer gel electrolyte. The optimum concentration of polymer gel electrolyte was determined as 20 wt% of TEOS in PVA (PE-1) with higher anodic peak and lower Rs and Rct values. The Galvanostatic charge-discharge tests were performed on the optimized gel system prototype battery. The highest capacity of 6.86 × 10-5 Ah at a current density of 0.2 mA cm-2 was achieved with an excellent capacity retention ratio of 85.7% over 500 cycles. The exceptional cycle performance and high capacity make PVA-TEOS gel electrolyte a promising candidate for practical battery application.

Novel Polyelectrolyte Complex Membranes Containing Carboxymethyl Cellulose-Gelatin for Pervaporation Dehydration of Azeotropic Bioethanol for Biofuel.

Polyelectrolyte complex membranes (PECMs) were prepared by combining sodium carboxymethyl cellulose (NaCMC) and gelatin (Ge) with variations in the Ge content in the NaCMC matrix. Characterization methods, such as infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), contact angle analysis (CA), and universal testing machines (UTM) were used to investigate the physicochemical studies of the prepared membranes. The pervaporation characteristics of membranes with Ge content were investigated using an azeotropic mixture of water and bioethanol. The obtained data revealed that the membrane with 15 mass% of Ge (M-3) showed a maximum flux of 7.8403 × 10-2 kg/m2·h with separation selectivity of 2917 at 30 °C. In particular, the total and water flux of PECMs are shown as very close to each other indicating that the fabricated membranes could be employed to successfully break the azeotropic point of water-bioethanol mixtures. Using temperature-dependent permeation and diffusion data, the Arrhenius activation parameters were calculated, and the obtained values of water permeation (Epw) were considerably smaller than bioethanol permeation (EpE). Developed membranes showed the positive heat of sorption (ΔHs), suggesting that Henry's sorption mode is predominant.

Experimental and Computational Study of Mechanical and Thermal Characteristics of h-BN and GNP Infused Polymer Composites for Elevated Temperature Applications.

Polymer-based nanocomposites are being considered as replacements for conventional materials in medium to high-temperature applications. This article aims to discover the synergistic effects of reinforcements on the developed polymer-based nanocomposite. An epoxy-based polymer composite was manufactured by reinforcing graphene nanoplatelets (GNP) and h-boron nitride (h-BN) nanofillers. The composites were prepared by varying the reinforcements with the step of 0.1 from 0.1 to 0.6%. Ultrasonication was carried out to ensure the homogenous dispersion of reinforcements. Mechanical, thermal, functional, and scanning electron microscopy (SEM) analysis was carried out on the novel manufactured composites. The evaluation revealed that the polymer composite with GNP 0.2 by wt % has shown an increase in load-bearing capacity by 265% and flexural strength by 165% compared with the pristine form, and the polymer composite with GNP and h-BN 0.6 by wt % showed an increase in load-bearing capacity by 219% and flexural strength by 114% when compared with the pristine form. Furthermore, the evaluation showed that the novel prepared nanocomposite reinforced with GNP and h-BN withstands a higher temperature, around 340 °C, which is validated by thermogravimetric analysis (TGA) trials. The numerical simulation model is implemented to gather the synthesised nanocomposite's best composition and mechanical properties. The minor error between the simulation and experimental data endorses the model's validity. To demonstrate the industrial applicability of the presented material, a case study is proposed to predict the temperature range for compressor blades of gas turbine engines containing nanocomposite material as the substrate and graphene/h-BN as reinforcement particles.

Association of Cord Blood Glucose, Sodium, Potassium, and Calcium Levels With Neonatal Birth Asphyxia: A Hospital-Based Study.

Context Neonatal birth/perinatal asphyxia is a serious condition with the potential to cause damage to various tissues of the body especially the brain. Hypoxia can cause metabolic disturbances, which in turn can lead to imbalances in the levels of glucose, electrolytes, and calcium, which can further worsen the condition. Early detection of these biochemical derangements and immediate correction can prevent the complications and lifelong disabilities of birth asphyxia due to injury to vital organs particularly the brain. The aim is to assess any correlation between the cord blood glucose, electrolytes, and calcium levels and the severity of birth asphyxia. Methods and material In this study, 50 birth asphyxia neonates with birth weight >2.5 kg, and a 5-minute Apgar score ≤ 6 at birth with clinical evidence of asphyxia were compared with healthy neonates with birth weight > 2.5 kg, and a 5-minute Apgar score > 7. In all the cases and controls, cord blood glucose was estimated by glucose oxidase and peroxidase (GOD-POD) method, total calcium by Arsenazo method, and sodium and potassium were estimated by ion-selective Electrode (ISE) method using fully automated biochemistry analyzers. Results The mean cord blood concentrations of glucose, sodium, potassium, and calcium were significantly lower among birth asphyxia neonates in comparison with that of controls (p < 0.05). The correlation coefficient (r) for the study variables among cases indicates that there is a low to moderate positive correlation between the 5-minute Apgar score which is a measure of severity of birth asphyxia and cord blood concentrations of glucose, sodium, and calcium. Conclusion In our study, birth asphyxiated neonates were found to have statistically significant low levels of cord blood glucose and electrolytes like sodium and calcium except for potassium. There was a low to moderate positive correlation between cord blood glucose and electrolyte concentrations with the severity of birth asphyxia. Analysis of cord blood for these simple biochemical tests can help pediatricians in the active management of birth asphyxia cases.

Fabrication and Characterization of Poly(vinyl alcohol)-chitosan-capped Silver Nanoparticle Hybrid Membranes for Pervaporation Dehydration of Ethanol.

Chitosan-capped silver nanoparticle (CS-capped AgNPs)-incorporated Poly(vinyl alcohol) (PVA) hybrid membranes were prepared by a solution-casting technique for ethanol dehydration via pervaporation. The incorporation of CS-capped AgNPs into the PVA membrane and its influence on membrane properties and pervaporation-separation process of azeotropic water/ethanol mixture was studied. The addition of CS-capped AgNPs into the PVA membrane reduced the crystallinity, thereby increasing the hydrophilicity and swelling degree of the hybrid membrane, supported by contact angle (CA) analyzer and swelling degree experiments, respectively. Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of polymeric matrix between PVA and CS and also the binding of AgNPs onto the functional group of CS and PVA, which was also reflected in the microstructure images demonstrated by scanning electron microscopy (SEM) and by 2θ angle of wide-angle X-ray diffraction (WAXD). The effect of CS-capped AgNPs on the thermal stability of the hybrid membrane was demonstrated by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). These characteristics of the hybrid membrane positively impact the efficiency of the dehydration of ethanol, as indicated by pervaporation experiments. The best performances in total flux (12.40 ± 0.20 × 10-2 kg/m2 h) and selectivity (3612.33 ± 6.03) at 30 °C were shown for CS-capped AgNPs PVA hybrid membrane containing 2 wt.% CS-capped AgNPs (M-4). This confirms that the developed hybrid membranes can be efficiently used to separate water from azeotropic aqueous ethanol.

Donut-like organization of inhibition underlies categorical neural responses in the midbrain.

Categorical neural responses underlie various forms of selection and decision-making. Such binary-like responses promote robust signaling of the winner in the presence of input ambiguity and neural noise. Here, we show that a 'donut-like' inhibitory mechanism in which each competing option suppresses all options except itself, is highly effective at generating categorical neural responses. It surpasses motifs of feedback inhibition, recurrent excitation, and divisive normalization invoked frequently in decision-making models. We demonstrate experimentally not only that this mechanism operates in the midbrain spatial selection network in barn owls, but also that it is necessary for categorical signaling by it. The functional pattern of neural inhibition in the midbrain forms an exquisitely structured 'multi-holed' donut consistent with this network's combinatorial inhibitory function for stimulus selection. Additionally, modeling reveals a generalizable neural implementation of the donut-like motif for categorical selection. Self-sparing inhibition may, therefore, be a powerful circuit module central to categorization.

Influence of Dy3+ ion concentration on photoluminescence and energy transfer mechanism of promising KBaScSi3O9 phosphors for warm white LEDs.

A novel white light emitting silicate-based phosphor of Dy3+ activated KBaScSi3O9 (xDyKBS) was prepared by a conventional solid state method. Powder X-ray diffraction patterns represent the pure phase of synthesized materials that was formed with monoclinic structure. The metal-ligand bonding nature and electronic band structure have been examined optical absorption spectra. The luminescence emission curves of the silicate phosphors display an intense yellow emission peak at 579 nm and a blue emission peak at 491 nm. Among the emission bands, the band observed in the yellow region due to 4F9/2→6H13/2 transition was found to be higher intensity. The radiative parameters like transition probabilities (AR), branching ratios (ßR) and stimulated emission cross-section (σPE) values were calculated using Judd-Ofelt parameters and refractive index values for the observed transitions in emission spectra. The life time measurements were made for 4F9/2 → 6H13/2 transition of all the studied samples by keeping an excitation at 350 nm and emission at 579 nm and decay curves were fitted to bi-exponential fitting method. The CCT values obtained from the color coordinates suggested that present xDyKBS phosphors can emit warm and neutral white light depending upon the dopant concentration under near-UV excitation. Our results demonstrated that the optimum concentration 0.05DyKBS phosphor can be successfully utilized as a promising and potential candidate for various innovative photonic applications like warm white LEDs, solar cells, optical sensors and lasers.

Development and Characterization of Biocompatible Membranes from Natural Chitosan and Gelatin for Pervaporative Separation of Water-Isopropanol Mixture.

Natural polymers have attracted a lot of interest in researchers of late as they are environmentally friendly, biocompatible, and possess excellent characters. Membranes forming natural polymers have provided a whole new dimension to the separation technology. In this work, chitosan-gelatin blend membranes were fabricated using chitosan as the base and varying the amount of gelatin. Transport, mechanical, and surface characteristics of the fabricated membranes were examined in detail by means of the characterizing techniques such as Fourier transform infrared spectroscopy, differential scanning colorimetry, wide angle X-ray diffraction, scanning electron microscope, and thermogravimetric analysis. In order to analyze the water affinity of the developed blend chitosan-gelatin membranes, the percentage degree of swelling was examined. Out of the fabricated membranes, the membrane loaded with 15 mass% of gelatin exhibited the better pervaporation performance with a pervaporation separation index value of 266 at 30 °C for the solution containing 10% in terms of the mass of water, which is the highest among the contemporary membranes. All the fabricated membranes were stable during the pervaporation experiments, and permeation flux of water for the fabricated membranes was dominant in the overall total permeation flux, signifying that the developed membranes could be chosen for efficient separation of water-isopropanol mixture on a larger scale.

Fabrication and Physicochemical Study of B2SA-Grafted Poly(vinyl Alcohol)-Graphene Hybrid Membranes for Dehydration of Bioethanol by Pervaporation.

Tetraethylorthosilicate (TEOS)-crosslinked poly(vinyl alcohol) (PVA) solution was prepared and treated with benzaldehyde 2 sulphonic sodium salt acid (B2SA) for sulfonation. Different contents of graphene were incorporated into B2SA-grafted PVA-TEOS hybrid membrane to improve the membrane stability, mechanical strength, and overall pervaporation performance of the membranes. Membranes were fabricated using the casting technique. Developed membranes were then analyzed for their physicochemical changes by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), contact angle analysis (CA), and mechanical strength. The lower d-spacing value observed in WAXD was evidence for the decreased inter-chain distance between the polymer chains. DSC exhibited the enhanced thermal stability of the developed membranes compared to the plane PVA membrane with enhancement in Tg value (106 °C), which was well above the pervaporation experimental temperature. Incorporation of graphene induced higher mechanical strength to the fabricated membranes. Further, the membranes were tested for the pervaporation separation of bioethanol. All the membranes were stable throughout the pervaporation studies, with M-2 G showing the total permeation flux of 11.66 × 10-2 kg/(m2 h) at 30 °C.

Nanoceramic Composites for Nuclear Radiation Attenuation.

The development of radiation attenuation materials with lean cross-sections is the need of the hour. However, the inherent threat of radiations accompanying these processes is of major concern. Thus, in an attempt to shield unnecessary radiations, several novel materials have been fabricated alongside the conventional materials available. Yet, there is a need for cost-effective, efficient shielding materials that have good mechanical strength and effective shielding properties. The present work investigates ceramic composite behaviors and radiation shielding capacity reinforced with lead oxide nano-powder. Developed nano-lead-based cement composites were subjected to mechanical tests to determine flexural and compressive strengths to check their suitability for structural applications. Further, the gamma attenuation test of the composites was conducted to determine their neutron absorption capacity. The addition of nano-leadoxide in the control beams was varied from 0.7 to 0.95 and 1 wt.% of the ceramic matrix. The percentage of nano-leadoxide that gives the best results in both enhanced properties and economic aspects was determined to be 0.6 wt.% of the cement.

Biodegradable carboxymethyl cellulose based material for sustainable packaging application.

The main goal of the present work was to develop a value-added product of biodegradable material for sustainable packaging. The use of agriculture waste-derived carboxymethyl cellulose (CMC) mainly is to reduce the cost involved in the development of the film, at present commercially available CMS is costly. The main focus of the research is to translate the agricultural waste-derived CMC to useful biodegradable polymer suitable for packaging material. During this process CMC was extracted from the agricultural waste mainly sugar cane bagasse and the blends were prepared using CMC (waste derived), gelatin, agar and varied concentrations of glycerol; 1.5% (sample A), 2% (sample B), and 2.5% (sample C) was added. Thus, the film derived from the sample C (gelatin + CMC + agar) with 2.0% glycerol as a plasticizer exhibited excellent properties than other samples A and B. The physiochemical properties of each developed biodegradable plastics (sample A, B, C) were characterized using Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA). The swelling test, solubility in different solvents, oil permeability coefficient, water permeability (WP), mechanical strength of the produced material was claimed to be a good material for packaging and meanwhile its biodegradability (soil burial method) indicated their environmental compatibility nature and commercial properties. The reflected work is a novel approach, and which is vital in the conversion of organic waste to value-added product development. There is also another way to utilize commercial CMC in preparation of polymeric blends for the packaging material, which can save considerable time involved in the recovery of CMC from sugarcane bagasse.

Mass spectral analysis of acetylated peptides: Implications in proteomics.

Sequence determination of peptides using mass spectrometry plays a crucial role in the bottom-up approaches for the identification of proteins. It is crucially important to minimise false detection and validate sequence of the peptides in order to correctly identify a protein. Chemical modification of peptides followed by mass spectrometry is an option for improving the spectral quality. In silico-derived tryptic peptides with different N-terminal amino acids were designed from human proteins and synthesized. The effect of acetylation on the fragmentation of peptides was studied. N-terminal acetylation of the tryptic peptides was shown to form b1-ions, improve the abundance and occurrence of b-ions. In some cases, the intensity and occurrence of some y-ions also varied. Thus, it is demonstrated that acetylation plays an important role in improving the de novo sequencing efficiency of the peptides. The acetylation method was extended to tryptic peptides generated from the proteome of an Antarctic bacterium Pseudomonas syringae Lz4W using the proteomics work flow and mass spectra of the peptides were analysed. Comparison of the MS/MS spectra of the acetylated and unacetylated peptides revealed that acetylation helped in improving the spectral quality and validated the peptide sequences. Using this method, 673 proteins of the 1070 proteins identified were validated.

Novel fabrication of PSSAMA_Na capped silver nanoparticle embedded sodium alginate membranes for pervaporative dehydration of bioethanol.

Polystyrene-4-sulfonic acid co maleic acid sodium salt (PSSAMA_Na) capped silver nanoparticle (Ag_Np) embedded sodium alginate (Na-Alg) nanocomposite membranes have been developed to improve the pervaporation (PV) dehydration of bioethanol. The effect of PSSAMA_Na capped Ag_Nps on the micro-morphology, physicochemical properties and separation performance of the derived membranes was analyzed as a function of temperature at the azeotropic composition of the bioethanol-water mixture. WAXD analysis shows a decrease in crystalline domains with the increase in PSSAMA_Na capped Ag_Nps content and confirms the presence of Ag_Nps. DSC analysis demonstrated that the hydrophilic nature enhances as the PSSAMA_Na capped Ag_Nps content increases in the membrane matrix. Further, both total permeation flux and separation selectivity were increased with an increase in PSSAMA_Na capped Ag_Nps content. The results revealed that the membrane with 3 mass% of PSSAMA_Na capped Ag_Nps exhibited the highest permeation flux (13.40 × 10-2 kg m-2 h-1) and separation selectivity (11 406) at 30 °C which indicate its better PV performance. The total permeation flux and permeation flux of water values were close to each other, which confirms that the membranes can be efficiently used to remove the water from azeotropic aqueous bioethanol.

Distinct recruitment of dorsomedial and dorsolateral striatum erodes with extended training.

Hypotheses of striatal orchestration of behavior ascribe distinct functions to striatal subregions, with the dorsolateral striatum (DLS) especially implicated in habitual and skilled performance. Thus neural activity patterns recorded from the DLS, but not the dorsomedial striatum (DMS), should be correlated with habitual and automatized performance. Here, we recorded DMS and DLS neural activity in rats during training in a task promoting habitual lever pressing. Despite improving performance across sessions, clear changes in corresponding neural activity patterns were not evident in DMS or DLS during early training. Although DMS and DLS activity patterns were distinct during early training, their activity was similar following extended training. Finally, performance after extended training was not associated with DMS disengagement, as would be predicted from prior work. These results suggest that behavioral sequences may continue to engage both striatal regions long after initial acquisition, when skilled performance is consolidated.