Investigation on thermochemical co-gasification of rice husk and groundnut shell in open core gasifier for the generation of producer gas: An optimization by central composite design.

Several energy-related strategies and scenarios have been suggested to address concerns about rising global temperatures. In addition to using renewable energy, the improvement in energy efficiency of conventional systems is also in focus. Policies are already in place in many countries, including India, to address the energy needs of rural and small-scale enterprises by gasifying locally available, diverse agricultural leftovers. Although rice husk and groundnut shell are two commonly used agricultural leftovers in the southern part of India, their appropriate blending must be studied to improve their conversion efficiency in co-gasification. Therefore, the primary objective of this research is to construct a statistical model utilizing response surface methodology (RSM) to analyze the thermochemical co-gasification of the aforementioned biomass materials. Since RSM can predict optimum performance with limited experimental data, this could contribute to the identification of the performance and operating parameters of an open-core gasifier. The model predicts that the mixture containing 20% rice husk and working at an ER of 0.25 and a reduction zone inlet temperature of 879.9 °C will be CO-23.53%, H2-13.97%, and CH4-3.56%. In addition, the lower heating value and gas yield can be as high as 6.17 MJ/Nm3 and 2.369 m3/kg, respectively. This outcome can contribute to the effective utilization of biomass for energy supply in rural areas. However, the economic parameters must be analyzed to implement the same in any region.

Potential drug-drug interactions among hospitalised TB patients.

BACKGROUND: Hospitalised TB patients are at heightened risk for developing drug-drug interactions (DDIs) due to overlapping CYP450 enzyme and/or drug transporter biotransformation of anti-TB drugs and co-medications given for treating TB-associated comorbidities. We aimed to compare the occurrence, characterisation and determinants of database identified potential DDIs (pDDIs) associated with first-line anti-TB drugs and other co-medications using a subscription and free access drug information database.METHOD: This was a single-centre retrospective study to assess pDDIs between first-line anti-TB drugs and other medications for comorbidities among hospitalised TB patients using IBM Micromedex® and Drugs.com.RESULTS: On multivariate regression analysis, hospitalised TB patients with comorbidities such as diabetes mellitus, HIV infection and hypertension, longer hospitalisation, and patients administered with more than seven drugs during their hospital stay were associated with increased risk for the occurrence of pDDIs. Significant discrepancies were observed in the detection and severity of pDDIs between IBM Micromedex and Drugs.com.CONCLUSION: We recommend using free access drug information database to a subscription drug information database in drug interaction screening protocols in clinics for enhanced identification of pDDIs and reducing monetary burden in resource-limited settings.

A comprehensive review on impacts of COVID-19 in food preservation and cold chain: An approach towards implementing green energy technologies.

Technology plays a crucial role in fighting COVID-19 pandemic. The COVID-19 pandemic impacts all facets of human life, including food preservation and supply chain. The changes in the food processing and preservation brings changes to the global food choice. In the age of the COVID-19 pandemic scare, the present article explores the framework for food security. It offers insights into food security with a focus on renewable energy to help rural farmers, besides, exploring the possibility of the diffusion of COVID-19 via food chain. This article indicates that the implementation of stand-alone and hybrid renewable energy systems is relatively fresh in food processing, preservation, and transportation chain. Green food preservation may be a revolutionary idea to address the challenges of the future to secure both producers and customers, besides, to improve the attractiveness of the ecological, economic, and creative sectors. This study reveals that the transformation can be achieved from a technological and economic point of view with the key steps to fulfill this goal in a cost-effective manner. The observation also shows a suitable methodology to identify the best energy, economic and environmental scenario towards fulfilling the energy needs in isolated areas.

Unraveling CoNiP-CoP2 3D-on-1D Hybrid Nanoarchitecture for Long-Lasting Electrochemical Hybrid Cells and Oxygen Evolution Reaction.

Evolving cost-effective transition metal phosphides (TMPs) using general approaches for energy storage is pivotal but challenging. Besides, the absence of noble metals and high electrocatalytic activity of TMPs allow their applicability as catalysts in oxygen evolution reaction (OER). Herein, CoNiP-CoP2 (CNP-CP) composite is in situ deposited on carbon fabric by a one-step hydrothermal technique. The CNP-CP reveals hybrid nanoarchitecture (3D-on-1D HNA), i.e., cashew fruit-like nanostructures and nanocones. The CNP-CP HNA electrode delivers higher areal capacity (82.8 µAh cm-2 ) than the other electrodes. Furthermore, a hybrid cell assembled with CNP-CP HNA shows maximum energy and power densities of 31 µWh cm-2 and 10.9 mW cm-2 , respectively. Exclusively, the hybrid cell demonstrates remarkable durability over 30 000 cycles. In situ/operando X-ray absorption near-edge structure analysis confirms the reversible changes in valency of Co and Ni elements in CNP-CP material during real-time electrochemical reactions.  Besides, a quasi-solid-state device unveils its practicability by powering electronic components. Meanwhile, the CNP-CP HNA verifies its higher OER activity than the other catalysts by revealing lower overpotential (230 mV). Also, it exhibits relatively small Tafel slope (38 mV dec-1 ) and stable OER activity over 24 h. This preparation strategy may initiate the design of advanced TMP-based materials for multifunctional applications.

A waste to energy technology for Enrichment of biomethane generation: A review on operating parameters, types of biodigesters, solar assisted heating systems, socio economic benefits and challenges.

Anaerobic Digestion (AD) is one of the promising wastestoenergy (WtE) technologies that convert organic wastes to useful gaseous fuel (biogas). In this process methane is produced in the presence of methanogens (bacteria). The survival and activities of methanogens are based on several parameters such as pH, temperature, organic loading rate, types of biodigester. Moreover, these parameters influence the production of biogas in terms of yield and composition. Maintaining an appropriate temperaturefor AD is highly critical and energy intensive. This study reviews the various hybrid technologies assistedbio gas production schemes particularly from renewable energy sources. Also discuss the direct and indirect solar assisted bio-digester impacts and recommendation to improve its performance. In addition, the performance analysis Solar Photovoltaic (PV) and thermal collector assisted bio gas plants; besides their impact on the performance of anaerobic digesters. Since opportunities of solar energy are attractive, the effective utilization of the same is selected for the discussion. Besides, the various constraints that affect the yield and composition of biogas are also evaluated along with the current biogas technologies and the biodigesters. The environmental benefits, challenges and socio-economic factors are also discussed for the successful implementation of various technologies.

One-Pot Hydrothermal-Derived NiS2 -CoMo2 S4 with Vertically Aligned Nanorods as a Binder-Free Electrode for Coin-Cell-Type Hybrid Supercapacitor.

Transition bimetallic sulfides are exploited as high-capacity electrode materials in energy storage devices owing to their abundant electroactive sites and relatively high electrical conductivity compared with metal oxides. Here, an in situ conversion of metal ions into NiS2 -CoMo2 S4 vertically aligned nanorod arrays on nickel foam (NS-CMS NRAs@NF) using a one-step hydrothermal technique to address the "dead-mass" limitation and multi-step preparation methods is reported. An in situ-converted NS-CMS NRAs obtained for 12 h of reaction time (NS-CMS NRAs-12 h@NF) delivers a superior areal capacity of 780 µAh cm-2 to the other NS-CMS electrodes synthesized for 6 h (543.1 µAh cm-2 ) and 18 h (636.7 µAh cm-2 ) at 7 mA cm-2 . A coin-cell-type hybrid supercapacitor (HSC) is also fabricated to unveil the practical adaptability of NS-CMS NRAs-12 h@NF electrode. Utilizing its structural and active material intriguing features, assembled coin-cell-type HSC achieves a high areal capacitance of 246.2 mF cm-2 (5 mA cm-2 ) along with maximum areal energy density (147 µWh cm-2 ) and power density (21.3 mW cm-2 ), respectively. Furthermore, the capability of coin-cell-type HSC in real-time applications is also inspected. This work promotes in situ deposition strategy to fabricate metal sulfide-based nanostructures for high-performance electrochemical capacitors.

Nanosilver-Particles Integrated Ni3 Sn2 S2 -CoS Composite as an Advanced Electrode for High Energy Density Hybrid Cell.

An ion-exchange process is a promising approach to design advanced electrode materials for high-performance energy storage devices. Herein, a nanostructured Ni3 Sn2 S2 -CoS (NSS-CS) composite is fabricated by successive hydrothermal and ion-exchange processes. Since the incorporation of redox-rich cobalt element enables the NSS-CS composite to be more electrochemically active, its impact on the electrochemical performance is therefore extensively studied. Particularly, the NSS-CS-0.2 g electrode material delivered a high areal capacity of 830.4 µAh cm-2 at 5 mA cm-2 . Additionally, a room-temperature wet-chemical approach is employed to anchor nanosilver (nAg)-particles on the NSS-CS-0.2 g (nAg@NSS-CS-0.2 g) to further exalt its electrokinetics. Consequently, the nAg@NSS-CS-0.2 g electrode shows a higher areal capacity of 948.5 µAh cm-2 (193.5 mAh g-1 ) than that of the NSS-CS-0.2 g. Furthermore, its practicability is also examined by assembling a hybrid cell. The assembled hybrid cell delivers a high areal capacity of 969.2 µAh cm-2 (49.2 mAh g-1 ) at 7 mA cm-2 and maximum areal energies and power densities of 0.784 mWh cm-2 (40.8 Wh kg-1 ) and 45 mW cm-2 (2347.4 W kg-1 ), respectively. The efficiency of the hybrid cells is also tested by harvesting solar energy, followed by energizing electronic components. This work can pave the way for significant attraction in designing advanced electrodes for energy-related fields.

Metal-Organic Framework-Derived Co3 V2 O8 @CuV2 O6 Hybrid Architecture as a Multifunctional Binder-Free Electrode for Li-Ion Batteries and Hybrid Supercapacitors.

Metal-organic frameworks (MOFs) are promising materials in diverse fields because of their constructive traits of varied structural topologies, high porosity, and high surface area. MOFs are also an ideal precursor/template to derive porous and functional morphologies. Herein, Co3 V2 O8 nanohexagonal prisms are grafted on CuV2 O6 nanorod arrays (CuV-CoV)-grown copper foam (CF) using solution-processing methods, followed by thermal treatment. Direct preparation of active material on CF can potentially eliminate electrochemically inactive and non-conductive binders, leading to improved charge-transfer rate. Furthermore, solution-processing methods are simple and cost-effective. Owing to versatile valence states and good redox activity, the vanadium-incorporated mixed metal oxides (CuV-CoV) exhibited superior electrochemical performance in lithium (Li)-ion battery and supercapacitor (SC) studies. Furthermore, hollow carbon particles (HCPs) derived from MOF particles (MOF-HCPs) are used as the anode material in SCs. A hybrid SC (HSC) fabricated with CuV-CoV and MOF-HCP materials exhibited noteworthy electrochemical properties. Moreover, a solid-state HSC (SSHSC) is constructed and its real-time feasibility is investigated by harvesting the dynamic energy of a bicycle with the help of a direct current generator. The charged SSHSCs potentially powered various electronic components.

Graphene Matrix Sheathed Metal Vanadate Porous Nanospheres for Enhanced Longevity and High-Rate Energy Storage Devices.

Rational design of anode materials comprising rich benefits of high capacity, superior rate capability, and exalted lifetime is of considerable significance in the progress of high-performance Li-ion batteries (LIBs) and supercapatteries. Herein, highly porous cobalt vanadate (Co2VO4) nanospheres encapsulated with reduced graphene oxide (rGO) nanosheets (rGO@CoV PNSs) were prepared by a facile hydrothermal method and employed as a hybrid composite-based anode material for energy storage devices. The nanocavities and porous features of CoV nanospheres, and the laminated rGO nanosheets over CoV PNSs can significantly surpass the volume changes and enhance the surface electrokinetics, respectively. With benefits of rich redox activity and constructive traits, the rGO@CoV PNSs as an electrode material in LIBs exhibited superior reversible capacity of 780.6 mAh/g after 100 cycles with remarkable rate performance. Moreover, the hybrid composite displayed an excellent reversible capacity of 531.8 mAh/g even after 1000 cycles performed at 1000 mA/g. Utilizing the synergistic features, the rGO@CoV PNSs composite was also explored as a battery-type electrode for supercapatteries. The fabricated supercapattery device with rGO@CoV PNSs and rGO demonstrated good rate performance including superior areal energy (0.048 mWh/cm2) and power (9.96 mW/cm2) densities. Therefore, the graphene sheathed metal vanadates would be an ultrahigh rate electrode candidates for energy storage devices.

Ternary MOF-Based Redox Active Sites Enabled 3D-on-2D Nanoarchitectured Battery-Type Electrodes for High-Energy-Density Supercapatteries.

Designing rationally combined metal-organic frameworks (MOFs) with multifunctional nanogeometries is of significant research interest to enable the electrochemical properties in advanced energy storage devices. Herein, we explored a new class of binder-free dual-layered Ni-Co-Mn-based MOFs (NCM-based MOFs) with three-dimensional (3D)-on-2D nanoarchitectures through a polarity-induced solution-phase method for high-performance supercapatteries. The hierarchical NCM-based MOFs having grown on nickel foam exhibit a battery-type charge storage mechanism with superior areal capacity (1311.4 µAh cm-2 at 5 mA cm-2), good rate capability (61.8%; 811.67 µAh cm-2 at 50 mA cm-2), and an excellent cycling durability. The superior charge storage properties are ascribed to the synergistic features, higher accessible active sites of dual-layered nanogeometries, and exalted redox chemistry of multi metallic guest species, respectively. The bilayered NCM-based MOFs are further employed as a battery-type electrode for the fabrication of supercapattery paradigm with biomass-derived nitrogen/oxygen doped porous carbon as a negative electrode, which demonstrates excellent capacity of 1.6 mAh cm-2 along with high energy and power densities of 1.21 mWh cm-2 and 32.49 mW cm-2, respectively. Following, the MOF-based supercapattery was further assembled with a renewable solar power harvester to use as a self-charging station for various portable electronic applications.

Fragmented QRS on electrocardiography as a predictor of myocardial scar in patients with hypertrophic cardiomyopathy.

Background: Fragmented QRS (fQRS) and Q waves are ECG findings in patients with myocardial scar. fQRS is more sensitive than pathological Q waves in detecting myocardial fibrosis in patients with coronary artery disease (CAD). Cardiac magnetic resonance (CMR) imaging is used for the diagnosis and for quantifying scar tissue in patients with HCM. Our aim was to correlate ECG parameters like fQRS and Q waves with the presence of late gadolinium enhancement (LGE) assessed by contrast CMR imaging to elucidate ECG markers which might predict scar tissue in HCM.Methods: This study is a retrospective analysis which included 39 patients who were diagnosed/suspected to have HCM on echocardiography and referred for contrast CMR imaging at our centre between 2010 and 2016. Presence of fQRS was correlated with scar demonstrated by LGE on CMR.Results: Twenty four (66.67%) patients had asymmetrical septal hypertrophy, 7 (19.44%) patients had apical involvement while 5 (13.89%) had concentric pattern. Only 4 (11.11%) patients had pathological Q waves in contiguous leads on surface ECG while fQRS in two contiguous leads was present in 23 (63.89%) patients. Presence of fQRS was more in patients with LGE on CMR than those without (84.61 versus 10%, p<.001). When presence of LGE in specific segments (anterior, lateral and inferior) was correlated with corresponding ECG leads, all the three segments showed significant correlation. The overall sensitivity, specificity, PPV and NPV of fQRS for predicting scar tissue were 84.6, 90.0, 95.6 and 69.2%, respectively.Conclusion: fQRS on surface ECG can be used as an indirect marker to predict the presence of fibrosis in HCM.

Synergistic Effects of Cobalt Molybdate@Phosphate Core-Shell Architectures with Ultrahigh Capacity for Rechargeable Hybrid Supercapacitors.

Designing binder-free and core-shell-like electrode materials with synergistic effects has attracted widespread attention for the development of high energy density hybrid supercapacitors (HSCs). Herein, binder-free cobalt molybdate nanosheet-laminated cobalt phosphate micropetals on nickel foam (CoM NS@CoP/NF) were facilely prepared for use as an effective battery-type electrode in HSCs. With the multifunctional features, the rationally combined core-shell-like CoM NS@CoP/NF electrode exhibited a maximum capacity of 886.8 µA h/cm2 at a current density of 5 mA/cm2 with a good rate capability of 64.2% and cycling stability of 87.4% (after 10 000 cycles). The high electrochemical performance of the hybrid composite could be attributed to the synergistic effects of hierarchical architectures and large accessible electroactive area, which facilitates the fast electron/transportation within the active material and accelerates the redox chemistry process. Utilizing the superior energy-storage properties, a pouch-type HSC was fabricated with core-shell-like CoM NS@CoP-6 h architectures as a battery-type electrode and activated carbon as a capacitive-type electrode in an aqueous alkaline electrolyte. The miniature hybrid device exhibited maximum energy and power densities of 0.44 mW h/cm2 and 40.35 mW/cm2, respectively, with good cycling stability. Moreover, the HSCs can energize various portable electronic equipments, which demonstrates their suitability for real-time applications.

An Integrated Approach Toward Renewable Energy Storage Using Rechargeable Ag@Ni0.67 Co0.33 S-Based Hybrid Supercapacitors.

Self-powered charging systems in conjunction with renewable energy conversion and storage devices have attracted promising attention in recent years. In this work, a prolific approach to design a wind/solar-powered rechargeable high-energy density pouch-type hybrid supercapacitor (HSC) is proposed. The pouch-type HSC is fabricated by engineering nature-inspired nanosliver (nano-Ag) decorated Ni0.67 Co0.33 S forest-like nanostructures on Ni foam (nano-Ag@NCS FNs/Ni foam) as a battery-type electrode and porous activated carbon as a capacitive-type electrode. Initially, the core-shell-like NCS FNs/Ni foam is prepared via a single-step wet-chemical method, followed by a light-induced growth of nano-Ag onto it for enhancing the conductivity of the composite. Utilizing the synergistic effects of forest-like nano-Ag@NCS FNs/Ni foam as a composite electrode, the fabricated device shows a maximum capacitance of 1104.14 mF cm-2 at a current density of 5 mA cm-2 and it stores superior energy and power densities of 0.36 mWh cm-2 and 27.22 mW cm-2 , respectively along with good cycling stability, which are higher than most of previous reports. The high-energy storage capability of HSCs is further connected to wind fans and solar cells to harvest renewable energy. The wind/solar charged HSCs can effectively operate various electronic devices for a long time, enlightening its potency for the development of sustainable energy systems.

Hierarchically Designed Ag@Ce6Mo10O39 Marigold Flower-Like Architectures: An Efficient Electrode Material for Hybrid Supercapacitors.

We facilely prepared silver nanoparticle-decorated Ce6Mo10O39 marigold flower-like structures (Ag NPs@CM MFs) for use as an effective positive material in hybrid supercapacitors (HSCs). With the aid of ethylenediaminetetraacetic acid (EDTA) as a chelating agent, self-assembled CM MFs were synthesized by a single-step hydrothermal method. When the electrochemical properties were tested in an aqueous alkaline electrolyte, the synthesized CM MFs with 0.15 g of EDTA exhibited a relatively high charge storage property (55.3 µA h/cm2 at 2 mA/cm2) with a battery-type redox behavior. The high capacity performance is mainly because of the large surface area of the CM MFs, and the hierarchically connected nanoflakes provide wide open wells for rapid accessibility of electrolyte ions and enable fast transportation of electrons. A further improvement in electrochemical performance was achieved (62 µA h/cm2 at 2 mA/cm2) by decorating Ag NPs on the surface of the CM MFs (i.e., Ag NPs@CM MFs), which is attributed to the increased electric conductivity. Considering the synergistic effect and the high electrochemical activity, Ag NPs@CM MFs were further employed as an effective positive electrode for the fabrication of pouch-type HSC with porous carbon (negative electrode) in an alkaline electrolyte. The HSC exhibited a high cell potential (1.5 V) with maximum energy and power densities of 0.0183 mW h/cm2 and 10.237 mW/cm2, respectively. The potency of HSC in practical applications was also demonstrated by energizing red and yellow light-emitting diodes as well as a three-point pattern torch light.

Achieving a High Areal Capacity with a Binder-Free Copper Molybdate Nanocone Array-Based Positive Electrode for Hybrid Supercapacitors.

Herein, we develop a binder-free copper molybdate nanocone array with a prism-like morphology on nickel foam (Cu3Mo2O9 NCAs/Ni foam) using a single-step hydrothermal method. With an optimal growth time (10 h) under hydrothermal conditions, the prism-like Cu3Mo2O9 NCAs are uniformly decorated on Ni foam with good adhesion and crystallinity. The prepared Cu3Mo2O9 NCAs/Ni foam has been directly used as a binder-free electrode to examine its suitability as a positive electrode in hybrid supercapacitors. In an aqueous 1 M KOH electrolyte, the binder-free Cu3Mo2O9 NCAs/Ni foam showed battery-type behavior with a high areal capacity of 449.5 µAh cm-2 at a discharge current density of 2 mA cm-2 and also exhibited a good cycling stability. In addition, the pouch-type hybrid supercapacitor is assembled using the prism-like Cu3Mo2O9 NCAs/Ni foam as a positive electrode and the activated carbon as a negative electrode in a 1 M KOH electrolyte. The hybrid supercapacitor achieves a maximum cell potential of 1.6 V with superior energy storage properties, including a high areal capacitance of 609.7 mF cm-2 at 3.5 mA cm-2, a high areal energy (0.21 mWh cm-2), and a high power density (2.73 mW cm-2). The obtained results suggest that the facilely synthesized Cu3Mo2O9 NCAs/Ni foam electrode has great potential in high-performance energy storage devices.

Fallen leaves derived honeycomb-like porous carbon as a metal-free and low-cost counter electrode for dye-sensitized solar cells with excellent tri-iodide reduction.

Utilizing carbon-based counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) have received much attention in recent times, owing to their low cost, good electrochemical activity, natural abundance and eco-friendly nature. Herein, we have facilely prepared quince leaves derived porous carbon (QLPC) using fallen quince leaves (QLs) and it was used as a cost-effective CE for the fabrication of DSSCs. By means of alkali treatment and pyrolysis process (at different temperatures of 700, 800 and 900 °C), the QLs powder undergoes chemical activation and carbonization, which results in a honeycomb-like QLPC with abundant micro/mesopores and large surface area. Simple and straightforward coating of QLPC samples onto fluorine doped tin oxide glass substrates led to improved electrocatalytic activity and good tri-iodide reduction in DSSCs. When the DSSCs were illuminated under 1 sun condition (AM 1.5; 100 mW cm-2), the device assembled with QLPC-based CE (prepared at 800 °C) showed a higher current density of ∼14.99 mA/cm2 and power conversion efficiency of ∼5.52% among the other QLPC-based CEs, which are comparable with the platinum-based CE in DSSCs. This facile process for the preparation of biomass derived carbon-based CE provides an alternative to the noble metal-free CE in DSSCs.

Wearable Fabrics with Self-Branched Bimetallic Layered Double Hydroxide Coaxial Nanostructures for Hybrid Supercapacitors.

We report a flexible battery-type electrode based on binder-free nickel cobalt layered double hydroxide nanosheets adhered to nickel cobalt layered double hydroxide nanoflake arrays on nickel fabric (NC LDH NFAs@NSs/Ni fabric) using facile and eco-friendly synthesis methods. Herein, we utilized discarded polyester fabric as a cost-effective substrate for in situ electroless deposition of Ni, which exhibited good flexibility, light weight, and high conductivity. Subsequently, the vertically aligned NC LDH NFAs were grown on Ni fabric by means of a hot-air oven-based method, and fluffy-like NC LDH NS branches are further decorated on NC LDH NFAs by a simple electrochemical deposition method. The as-prepared core-shell-like nanoarchitectures improve the specific surface area and electrochemical activity, which provides the ideal pathways for electrolyte diffusion and charge transportation. When the electrochemical performance was tested in 1 M KOH aqueous solution, the core-shell-like NC LDH NFAs@NSs/Ni fabric electrode liberated a maximum areal capacity of 536.96 µAh/cm2 at a current density of 2 mA/cm2 and excellent rate capability of 78.3% at 30 mA/cm2 (420.5 µAh/cm2) with a good cycling stability. Moreover, a fabric-based hybrid supercapacitor (SC) was assembled, which achieves a stable operational potential window of 1.6 V, a large areal capacitance of 1147.23 mF/cm2 at 3 mA/cm2, and a high energy density of 0.392 mWh/cm2 at a power density of 2.353 mW/cm2. Utilizing such high energy storage abilities and flexible properties, the fabricated hybrid SC operated the wearable digital watch and electric motor fan for real-time applications.

Correspondence between visual and electrical input filters of ON and OFF mouse retinal ganglion cells.

OBJECTIVE: Over the past two decades retinal prostheses have made major strides in restoring functional vision to patients blinded by diseases such as retinitis pigmentosa. Presently, implants use single pulses to activate the retina. Though this stimulation paradigm has proved beneficial to patients, an unresolved problem is the inability to selectively stimulate the on and off visual pathways. To this end our goal was to test, using white noise, voltage-controlled, cathodic, monophasic pulse stimulation, whether different retinal ganglion cell (RGC) types in the wild type retina have different electrical input filters. This is an important precursor to addressing pathway-selective stimulation. APPROACH: Using full-field visual flash and electrical and visual Gaussian noise stimulation, combined with the technique of spike-triggered averaging (STA), we calculate the electrical and visual input filters for different types of RGCs (classified as on, off or on-off based on their response to the flash stimuli). MAIN RESULTS: Examining the STAs, we found that the spiking activity of on cells during electrical stimulation correlates with a decrease in the voltage magnitude preceding a spike, while the spiking activity of off cells correlates with an increase in the voltage preceding a spike. No electrical preference was found for on-off cells. Comparing STAs of wild type and rd10 mice revealed narrower electrical STA deflections with shorter latencies in rd10. SIGNIFICANCE: This study is the first comparison of visual cell types and their corresponding temporal electrical input filters in the retina. The altered input filters in degenerated rd10 retinas are consistent with photoreceptor stimulation underlying visual type-specific electrical STA shapes in wild type retina. It is therefore conceivable that existing implants could target partially degenerated photoreceptors that have only lost their outer segments, but not somas, to selectively activate the on and off visual pathways.

Birnessite-type MnO2 nanosheet arrays with interwoven arrangements on vapor grown carbon fibers as hybrid nanocomposites for pseudocapacitors.

Manganese dioxide nanosheet arrays with interconnected arrangements are easily synthesized on vapor grown carbon fibers (MnO2 NSAs@VCFs) by a simple wet-chemical method at low temperature. The conductive nature of the VCFs serves as a scaffold and easily reduces potassium permanganate species for the formation of hierarchical MnO2 NSAs@VCFs. When utilized as an electroactive material for pseudocapacitors, the sophisticated configuration of the nanocomposite provides an effective electrochemical activity and an electron pathway for higher electrochemical performance in 1 M Na2SO4 aqueous solution. The hierarchical MnO2 NSAs@VCFs exhibit a maximum specific capacitance of 115.3 F g-1 at a current density of 0.5 A g-1 with an excellent cycling stability of 85.6% after 2000 cycles at a current density of 5 A g-1. Such facile and cost-effective fabrication of a metal oxide nanocomposite with improved electrochemical performance allows it to be considered as a promising electroactive material for energy storage devices.

Tickling the retina: integration of subthreshold electrical pulses can activate retinal neurons.

OBJECTIVE: The field of retinal prosthetics has made major progress over the last decade, restoring visual percepts to people suffering from retinitis pigmentosa. The stimulation pulses used by present implants are suprathreshold, meaning individual pulses are designed to activate the retina. In this paper we explore subthreshold pulse sequences as an alternate stimulation paradigm. Subthreshold pulses have the potential to address important open problems such as fading of visual percepts when patients are stimulated at moderate pulse repetition rates and the difficulty in preferentially stimulating different retinal pathways. APPROACH: As a first step in addressing these issues we used Gaussian white noise electrical stimulation combined with spike-triggered averaging to interrogate whether a subthreshold sequence of pulses can be used to activate the mouse retina. MAIN RESULTS: We demonstrate that the retinal network can integrate multiple subthreshold electrical stimuli under an experimental paradigm immediately relevant to retinal prostheses. Furthermore, these characteristic stimulus sequences varied in their shape and integration window length across the population of retinal ganglion cells. SIGNIFICANCE: Because the subthreshold sequences activate the retina at stimulation rates that would typically induce strong fading (25 Hz), such retinal 'tickling' has the potential to minimize the fading problem. Furthermore, the diversity found across the cell population in characteristic pulse sequences suggests that these sequences could be used to selectively address the different retinal pathways (e.g. ON versus OFF). Both of these outcomes may significantly improve visual perception in retinal implant patients.