Utilization of compressible hydrogels as electrolyte materials for supercapacitor applications.

Utilization of CoO@Co3O4-x-Ag (x denotes 1, 3, and 5 wt% of Ag) nanocomposites as supercapacitor electrodes is the main aim of this study. A new low-temperature wet chemical approach is proposed to modify the commercial cobalt oxide material with silver nanoparticle (NP) balls of size 1-5 nm. The structure and morphology of the as-prepared nanocomposites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption-desorption measurements. Hydrogels known to be soft but stable structures were used here as perfect carriers for conductive nanoparticles such as carbons. Furthermore, hydrogels with a large amount of water in their network can give more flexibility to the system. Fabrication of an electrochemical cell can be achieved by combining these materials with a layer-by-layer structure. The performance characteristics of the cells were examined by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge discharge (GCD). Cobalt oxide modified with 5 wt% Ag gave the best supercapacitor results, and the cell offers a specific capacitance of ∼38 mF cm-2 in two-electrode configurations.

Vanadium oxide nanorods as an electrode material for solid state supercapacitor.

The electrochemical properties of metal oxides are very attractive and fascinating in general, making them a potential candidate for supercapacitor application. Vanadium oxide is of particular interest because it possesses a variety of valence states and is also cost effective with low toxicity and a wide voltage window. In the present study, vanadium oxide nanorods were synthesized using a modified sol-gel technique at low temperature. Surface morphology and crystallinity studies were carried out by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. To the best of our knowledge, the as-prepared nanorods were tested with magnesium ion based polymer gel electrolyte for the first time. The prepared supercapacitor cell exhibits high capacitance values of the order of ~ 141.8 F g-1 with power density of ~ 2.3 kW kg-1 and energy density of ~ 19.1 Wh kg-1. The cells show excellent rate capability and good cycling stability.

Review on Fluorescent Carbon/Graphene Quantum Dots: Promising Material for Energy Storage and Next-Generation Light-Emitting Diodes.

Carbon/graphene quantum dots are 0D fluorescent carbon materials with sizes ranging from 2 nm to around 50 nm, with some attractive properties and diverse applications. Different synthesis routes, bandgap variation, higher stability, low toxicity with tunable emission, and the variation of physical and chemical properties with change in size have drawn immense attention to its potential application in different optoelectronics-based materials, especially advanced light-emitting diodes and energy storage devices. WLEDs are a strong candidate for the future of solid-state lighting due to their higher luminance and luminous efficiency. High-performance batteries play an important part in terms of energy saving and storage. In this review article, the authors provide a comparative analysis of recent and ongoing advances in synthesis (top-down and bottom-up), properties, and wide applications in different kinds of next-generation light-emitting diodes such as WLEDs, and energy storage devices such as batteries (Li-B, Na-B) and supercapacitors. Furthermore, they discuss the potential applications and progress of carbon dots in battery applications such as electrode materials. The authors also summarise the developmental stages and challenges in the existing field, the state-of-the-art of carbon/graphene quantum dots, and the potential and possible solutions for the same.

Electrical, electrochemical and structural studies of a chlorine-derived ionic liquid-based polymer gel electrolyte.

In the present article, an ionic liquid-based polymer gel electrolyte was synthesized by using poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) as a host polymer. The electrolyte films were synthesized by using the solution casting technique. The as-prepared films were free-standing and transparent with good dimensional stability. Optimized electrolyte films exhibit a maximum room-temperature ionic conductivity of σ = 8.9 × 10-3 S·cm-1. The temperature dependence of the prepared polymer gel electrolytes follows the thermally activated behavior of the Vogel-Tammann-Fulcher equation. The total ionic transference number was ≈0.91 with a wider electrochemical potential window of 4.0 V for the prepared electrolyte film which contains 30 wt % of the ionic liquid. The optimized films have good potential to be used as electrolyte materials for energy storage applications.

Surface Modification of Nanocrystalline LiMn2O4 Using Graphene Oxide Flakes.

In this work, a facile, wet chemical synthesis was utilized to achieve a series of lithium manganese oxide (LiMn2O4, (LMO) with 1-5%wt. graphene oxide (GO) composites. The average crystallite sizes estimated by the Rietveld method of LMO/GO nanocomposites were in the range of 18-27 nm. The electrochemical performance was studied using CR2013 coin-type cell batteries prepared from pristine LMO material and LMO modified with 5%wt. GO. Synthesized materials were tested as positive electrodes for Li-ion batteries in the voltage range between 3.0 and 4.3 V at room temperature. The specific discharge capacity after 100 cycles for LMO and LMO/5%wt. GO were 84 and 83 mAh g-1, respectively. The LMO material modified with 5%wt. of graphene oxide flakes retained more than 91% of its initial specific capacity, as compared with the 86% of pristine LMO material.

Solution combustion synthesis of a nanometer-scale Co3O4 anode material for Li-ion batteries.

A novel solution combustion synthesis of nanoscale spinel-structured Co3O4 powder was proposed in this work. The obtained material was composed of loosely arranged nanoparticles whose average diameter was about 36 nm. The as-prepared cobalt oxide powder was also tested as the anode material for Li-ion batteries and revealed specific capacities of 1060 and 533 mAh·g-1 after 100 cycles at charge-discharge current densities of 100 and 500 mA·g-1, respectively. Moreover, electrochemical measurements indicate that even though the synthesized nanomaterial possesses a low active surface area, it exhibits a relatively high specific capacity measured at 100 mA·g-1 after 100 cycles and a quite good rate capability at current densities between 50 and 5000 mA·g-1.

A switchable ceramide transfer protein for dissecting the mechanism of ceramide-induced mitochondrial apoptosis.

Mitochondrial translocation of ceramides triggers Bax-dependent apoptosis. To elucidate how ceramides activate Bax and commit cells to death, we developed a switchable version of the ceramide transfer protein CERT, sCERT. Upon its drug-induced recruitment to mitochondria, sCERT retains the ability to bind VAP proteins in the ER and catalyzes mitochondrial import of externally added fluorescent ceramides. Mitochondrial recruitment of sCERT also triggers mitochondrial translocation of Bax. The ability of mitochondria-bound sCERT to mediate ceramide import and Bax translocation requires both its START domain and ongoing ceramide biosynthesis. These data extend our previous finding that mistargeting of ER ceramides to mitochondria specifically activates Bax and establish sCERT as a novel tool to dissect the underlying mechanism in a time-resolved manner.

Formation and Characterization of Hole Nanopattern on Photoresist Layer by Scanning Near-Field Optical Microscope.

Patterning of lines of holes on a layer of positive photoresist SX AR-P 3500/6 (Allresist GmbH, Strausberg, Germany) spin-coated on a quartz substrate is carried out by using scanning near-field optical lithography. A green 532 nm-wavelength laser, focused on a backside of a nanoprobe of 90 nm diameter, is used as a light source. As a result, after optimization of parameters like laser power, exposure time, or sleep time, it is confirmed that it is possible to obtain a uniform nanopattern structure in the photoresist layer. In addition, the lines of holes are characterized by a uniform depth (71-87 nm) and relatively high aspect ratio ranging from 0.22 to 0.26. Numerical modelling performed with a rigorous method shows that such a structure can be potentially used as a phase zone plate.

Osteoporosis and skeletal dysplasia caused by pathogenic variants in SGMS2.

Mechanisms leading to osteoporosis are incompletely understood. Genetic disorders with skeletal fragility provide insight into metabolic pathways contributing to bone strength. We evaluated 6 families with rare skeletal phenotypes and osteoporosis by next-generation sequencing. In all the families, we identified a heterozygous variant in SGMS2, a gene prominently expressed in cortical bone and encoding the plasma membrane-resident sphingomyelin synthase SMS2. Four unrelated families shared the same nonsense variant, c.148C>T (p.Arg50*), whereas the other families had a missense variant, c.185T>G (p.Ile62Ser) or c.191T>G (p.Met64Arg). Subjects with p.Arg50* presented with childhood-onset osteoporosis with or without cranial sclerosis. Patients with p.Ile62Ser or p.Met64Arg had a more severe presentation, with neonatal fractures, severe short stature, and spondylometaphyseal dysplasia. Several subjects had experienced peripheral facial nerve palsy or other neurological manifestations. Bone biopsies showed markedly altered bone material characteristics, including defective bone mineralization. Osteoclast formation and function in vitro was normal. While the p.Arg50* mutation yielded a catalytically inactive enzyme, p.Ile62Ser and p.Met64Arg each enhanced the rate of de novo sphingomyelin production by blocking export of a functional enzyme from the endoplasmic reticulum. SGMS2 pathogenic variants underlie a spectrum of skeletal conditions, ranging from isolated osteoporosis to complex skeletal dysplasia, suggesting a critical role for plasma membrane-bound sphingomyelin metabolism in skeletal homeostasis.

Helix-Coil Transition Signatures B-Raf V600E Mutation and Virtual Screening for Inhibitors Directed Against Mutant B-Raf.

BACKGROUND: Mutation in the B RAF at V600E has been well implicated in the carcinogenesis that makes it as an attractive therapeutictarget. In the present study, we sought to identify the basis of V600E mutation at functional and structural grounds. The study also endeavors in identification of small molecule as a potential candidate with considerable pharmacological profile than available BRAF inhibitors through computational approaches. METHODS: The functional effects of V600E mutation was predicted using SIFT and Polyphen servers. Protein structural alterations werepredicted using SDM server and RMSD calculations. Virtual screening was performed considering existing BRAF inhibitors viz., Vemurafenib, Sorafenib, Dabrfenib, Trametinibthat formed query compounds for shape similarity search by Tanimoto similarity indices with a threshold of 95%. Compound with high affinity as similar to query compound was retrieved and screened for its ADMET properties. RESULTS: The SNP was shown to be highly vulnerable to malfunction and have damaging effects. Mutated protein showed that the secondary structure was irregular and side chain hydrogen bonds were unsaturated. The superimposition of wild onto mutated V600E BRAF revealed helix-coil transition occurring wherein residues Val 502, Leu 505, Arg506, Lys 507 assumed coiled conformation in the mutated BRAF. Virtual screening led to identification of SCHEMBL298689 akin to Vemurafenib as high affinity B-Raf inhibitors; with least toxicity and optimal bioactivity. CONCLUSION: In the present investigation, we put forth the structural and functional basis of B RAF V600E mutation showing helix coil transitions. In addition identified high affinity compound targeting V600E B RAF through virtual screening.

Membrane contact sites, ancient and central hubs of cellular lipid logistics.

Membrane contact sites (MCSs) are regions where two organelles are closely apposed to facilitate molecular communication and promote a functional integration of compartmentalized cellular processes. There is growing evidence that MCSs play key roles in controlling intracellular lipid flows and distributions. Strikingly, even organelles connected by vesicular trafficking exchange lipids en bulk via lipid transfer proteins that operate at MCSs. Herein, we describe how MCSs developed into central hubs of lipid logistics during the evolution of eukaryotic cells. We then focus on how modern eukaryotes exploit MCSs to help solve a major logistical problem, namely to preserve the unique lipid mixtures of their early and late secretory organelles in the face of extensive vesicular trafficking. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.

Diverting CERT-mediated ceramide transport to mitochondria triggers Bax-dependent apoptosis.

A deregulation of ceramide biosynthesis in the endoplasmic reticulum (ER) is frequently linked to induction of mitochondrial apoptosis. Although in vitro studies suggest that ceramides might initiate cell death by acting directly on mitochondria, their actual contribution to the apoptotic response in living cells is unclear. Here, we have analyzed the consequences of targeting the biosynthetic flow of ceramides to mitochondria using a ceramide transfer protein (encoded by COL4A3BP) equipped with an OMM anchor, mitoCERT. Cells expressing mitoCERT import ceramides into mitochondria and undergo Bax-dependent apoptosis. Apoptosis induction by mitoCERT was abolished through (i) removal of its ceramide transfer domain, (ii) disruption of its interaction with VAMP-associated proteins (VAPs) in the ER, (iii) addition of antagonistic CERT inhibitor HPA12, (iv) blocking de novo ceramide synthesis and (v) targeting of a bacterial ceramidase to mitochondria. Our data provide the first demonstration that translocation of ER ceramides to mitochondria specifically commits cells to death and establish mitoCERT as a valuable new tool to unravel the molecular principles underlying ceramide-mediated apoptosis.

Sphingomyelin synthase-related protein SMSr is a suppressor of ceramide-induced mitochondrial apoptosis.

Cells synthesize ceramides in the endoplasmic reticulum (ER) as precursors for sphingolipids to form an impermeable plasma membrane. As ceramides are engaged in apoptotic pathways, cells would need to monitor their levels closely to avoid killing themselves during sphingolipid biosynthesis. How this is accomplished remains to be established. Here we identify SMSr (SAMD8), an ER-resident ceramide phosphoethanolamine (CPE) synthase, as a suppressor of ceramide-mediated cell death. Disruption of SMSr catalytic activity causes a rise in ER ceramides and their mislocalization to mitochondria, triggering a mitochondrial pathway of apoptosis. Blocking de novo ceramide synthesis, stimulating ceramide export from the ER or targeting a bacterial ceramidase to mitochondria rescues SMSr-deficient cells from apoptosis. We also show that SMSr-catalyzed CPE production, although essential, is not sufficient to suppress ceramide-induced cell death and that SMSr-mediated ceramide homeostasis requires the N-terminal sterile α-motif, or SAM domain, of the enzyme. These results define ER ceramides as bona fide transducers of mitochondrial apoptosis and indicate a primary role of SMSr in monitoring ER ceramide levels to prevent inappropriate cell death during sphingolipid biosynthesis.