Studying the Effect of Operating Conditions and NO2 Cathode Contamination on PEM Fuel Cells Using Distribution Function of Relaxation Times Analysis.

The effect of NO2, an air pollutant, on the durability of polymer electrolyte membrane fuel cells (PEMFCs) and the affected electrochemical processes in the PEMFC following the contamination were investigated. In-situElectrochemical Impedance Spectroscopy (EIS) measurements were conducted on PEMFCs under different operating conditions of temperature and relative humidity (RH). NO2 was introduced to the cathode inlet flow. Analyses of the EIS measurements were performed using a genetic algorithm called ISGP (Impedance Spectroscopy by Genetic Programming) to obtain the distribution function of relaxation times (DFRT, a.k.a. DRT) models. Utilizing ISGP enabled us to differentiate the various phenomena in PEMFC and study how they are affected by NO2 contamination. Moreover, the experiments demonstrate the effectiveness of the mitigation method to flush the PEMFC and regenerate its performance after being contaminated, particularly at low operating temperatures. Energy-dispersive X-ray spectroscopy (EDS) technique is performed on the contaminated PEMFC to detect the presence of any nitrogen components in the FC's gas diffusion layer and the catalyst layer post the mitigation step. Cyclic Voltammetry is also performed on the contaminated cell to determine the effect of the contamination on the electrochemically active surface area of the cathode by evaluating the double-layer capacitance.

Scalable, Flexible, Magnetic-Field-Guided rULGO Sponge-BN-Cobalt Oxide-Based Supercapacitors: Mechanistic Insights into Multiple Charge Transfer Pathways by the Distribution of Relaxation Times.

Scalable and flexible supercapacitors are in high demand from an application point of view. Through our exploration, we have attained promising performance of electrochemical energy storage under the influence of an external magnetic field for future energy-based applications. In this work, a commercial sponge is used as a template for ultra-large graphene oxide (rULGO) functionalization, followed by the incorporation of Co3O4:BN without the inclusion of binders or conductive additives. The fabricated electrodes, namely, SPG-rULGO and SPG-rULGO-Co3O4:BN, demonstrate superior performance with a potential window of 2.2 V at a magnetic field strength of 13.5 and 28 mT, respectively. A specific capacitance of 218 ± 5% F·g-1 and 312 ± 5% F·g-1, respectively, with retention rates of 80 and 88% over 5000 charge-discharge cycles are achieved. In contrast to the conventional fabrication of the asymmetric device, both electrodes are made using flexible substrates with SPG-rULGO-Co3O4:BN as the positive electrode and SPG-rULGO as the negative electrode eliminating the need to use activated carbon. This configuration yields a specific capacitance of 153 ± 5% F·g-1 at 1 Ag-1, leading to a high energy density of 103 ± 5% W·h·kg-1 at a power density of 1.10 ± 5% kW kg-1 with an 85% retention rate. The charge-discharge mechanism of bare and modified electrodes is probed by the distribution of relaxation time analysis of the coupled electrochemical impedance spectra. The integration of magnetic field with advanced electrode materials opens up other possibilities for optimizing energy storage systems and advancing the field of flexible and mechanically robust supercapacitors.

Magnetically Triggered Interplay of Capacitive and Diffusion Contributions for Boosted Supercapacitor Performance.

The chemistry involved in supercapacitors in terms of their mechanistic contributions leading to improved specific capacity will aid in easy commercialization. The main contributory factors in a supercapacitor are either capacitive (non-diffusion controlled) or ion-diffusion behavior, which results in enhanced charge-discharge characteristics of a supercapacitor reflected in its power density, whereas ion-diffusion behavior will lead to the enhanced energy density of a supercapacitor. In this context, the present article attempts to understand the use of external magnetic fields, leading to the interplay between capacitive and ion-diffusion behavior in a high-performance supercapacitor. The model system chosen in the present study, nickel cobalt copper carbonate hydroxide (NiCoCuCH), can effectively address the interplay between capacitive and ion diffusion contributions by varying total magnetic effects involving magnetic dilution. The magneto-enhancement of the electrodes nickel cobalt copper carbonate hydroxide (NiCoCuCH) and aluminum-doped nickel cobalt copper carbonate hydroxide (Al-NiCoCuCH) was demonstrated under the magnetic field from 0 to 250 mT. Both NiCoCuCH and Al-NiCoCuCH show dominant non-diffusion-controlled (capacitive) and diffusion-controlled behavior as a function of the applied external magnetic field. Under the influence of the external magnetic field, ferromagnetic coupling between metal-oxygen-metal centers via oxygen 2p orbitals enhances, leading to a facile redox pathway. To further control the charge-discharge behavior of the electrode via the interplay between diffusive and capacitive, a non-magnetic ion, Al3+, was doped into the bare metal carbonate hydroxide crystal lattice. The Al3+ ion not only alters the crystal symmetry but also restricts the alignment of the magnetic domains in the electrode, leading to a sluggish redox pathway, effectively increasing the capacitive contribution, and leading to improved charge-discharge characteristics at the expense of energy density. We have constructed an asymmetric device with the best-performing (110 mT) NiCoCuCH electrode as a positive electrode and activated carbon as a negative electrode. The NiCoCuCH/AC ASC device at 110 mT has the largest specific capacity (1100 C g-1 at 2 A g-1) at 110 mT, leading to a high energy density (250 W h kg-1) and a power density (1.7 kW kg-1) of the electrode.

Structurally flexible pyrrolidinium- and morpholinium-based ionic liquid electrolytes.

Ion transport measures and details as well as physico-chemical and electrochemical properties are presented for a small set of structurally flexible pyrrolidinium (Pyrr) and morpholinium (Morph) cation-based ionic liquids (ILs), all with oligoether phosphate-based anions. All have high thermal stabilities, low glass transition temperatures, and wide electrochemical stability windows, but rather moderate ionic conductivities, where both the anions and the cations of the Pyrr-based ILs diffuse faster than those of the Morph-based ILs. Overall, the Pyrr-based ILs show significantly more promise as high-temperature supercapacitor electrolytes, rendering a specific capacitance of 164 F g-1 at 1 mV s-1, a power density of 609 W kg-1 and a specific energy density of 27 W h kg-1 at 90 °C in a symmetric graphite supercapacitor.

Ionic Liquids and Electrolytes with Flexible Aromatic Anions.

Five new n-tetrabutylphosphonium (P4444 )+ cation-based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 °C), phase behaviour (Tg <-55 °C) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.

Ambient temperature liquid salt electrolytes.

Alkali metal salts usually have high melting points due to strong electrostatic interactions and solvents are needed to create ambient temperature liquid electrolytes. Here, we report on six phosphate-anion-based alkali metal salts, Li/Na/K, all of which are liquids at room temperature, with glass transition temperatures ranging from -61 to -29 °C, and are thermally stable up to at least 225 °C. While the focus herein is on various physico-chemical properties, these salts also exhibit high anodic stabilities, up to 6 V vs. M/M+ (M = Li/Na/K), and deliver some battery performance - at elevated temperatures as there are severe viscosity limitations at room-temperature. While the battery performance arguably is sub-par, solvent-free electrolytes based on alkali metal salts such as these should pave the way for conceptually different Li/Na/K-batteries, either by refined anion design or by using several salts to create eutectic mixtures.

Meta-analytic connectivity modelling of functional magnetic resonance imaging studies in autism spectrum disorders.

Social and non-social deficits in autism spectrum disorders (ASD) persist into adulthood and may share common regions of aberrant neural activations. The current meta-analysis investigated activation differences between ASD and neurotypical controls irrespective of task type. Activation likelihood estimation meta-analyses were performed to examine consistent hypo-activated and/or hyper-activated regions for all tasks combined, and for social and non-social tasks separately; meta-analytic connectivity modelling and behavioral/paradigm analyses were performed to examine co-activated regions and associated behaviors. One hundred studies (mean age range = 18-41 years) were included. For all tasks combined, the ASD group showed significant (p < .05) hypo-activation in one cluster around the left amygdala (peak - 26, -2, -20, volume = 1336 mm3, maximum ALE = 0.0327), and this cluster co-activated with two other clusters around the right cerebellum (peak 42, -56, -22, volume = 2560mm3, maximum ALE = 0.049) Lobule VI/Crus I and the left fusiform gyrus (BA47) (peak - 42, -46, -18, volume = 1616 mm3, maximum ALE = 0.046) and left cerebellum (peak - 42, -58, -20, volume = 1616mm3, maximum ALE = 0.033) Lobule VI/Crus I. While the left amygdala was associated with negative emotion (fear) (z = 3.047), the left fusiform gyrus/cerebellum Lobule VI/Crus I cluster was associated with language semantics (z = 3.724) and action observation (z = 3.077). These findings highlight the left amygdala as a region consistently hypo-activated in ASD and suggest the potential involvement of fusiform gyrus and cerebellum in social cognition in ASD. Future research should further elucidate if and how amygdala-fusiform/cerebellar connectivity relates to social and non-social cognition in adults with ASD.

Vanadium Oxide Nanosheet-Infused Functionalized Polysulfone Bipolar Membrane for an Efficient Water Dissociation Reaction.

A high-performing bipolar membrane (BPM) was fabricated using functionalized polysulfones as the ion-exchange layers (IELs) and two-dimensional (2D) V2O5-nanosheets blended with polyvinyl alcohol (PVA) as the water dissociation catalyst (WDC) at the interfacial layer. The composite BPM showed a low resistance of 0.79 Ω cm2, confirming the good contact between the IEL and WDC, much needed for the ionic conductivity. It also demonstrated high water dissociation performance with a water dissociation voltage of 1.11 V corresponding to a current density of 1.02 mA/cm2 in the presence of a 1 M NaCl electrolytic solution. The functionalization of the polysulfone with -SO3- and R4N+ groups successfully resulted in the increase of hydrophilicity of the polymer, thereby increasing the water uptake capacity of the membranes. The blending of 2D V2O5 nanosheets with PVA proved to be an effective WDC, as confirmed by the increased conductivity and efficiency of the water dissociation (WD) reaction. The 2D V2O5-ns have great potential toward water adsorption onto its surface, thereby interacting with the water molecules, weakening the bonding force of water, and dissociating it into H+ and OH-. The transportation of coions across the membranes and generation of protons and hydroxyl ions at the interfacial layer are correlated with the change in the pH of the catholyte and anolyte as a function of current density during the WD reaction. The high performance of the composite BPM (BPM_VO-ns) was demonstrated at a higher current density of 100 mA/cm2 with a WD resistance of 0.027 Ω cm2. The durability was tested by subjecting it to 45 h of run at lower (1.02 mA/cm2) and higher (100 mA/cm2) current densities which display a negligible change in the interlayer voltage. Thus, the fabricated composite BPMs pave the way to be utilized for efficient and durable WD reactions under neutral electrolytic conditions.

Spectator-metal-ion-guided redox-dominant cobalt oxyhydroxide as a high-performance supercapacitor.

The ability of spectator metal ions such as vanadium to enhance the electrochemical performance of supercapacitors has been explained. Vanadium-incorporated CoO(OH) combined with NiMn-layered double hydroxide (LDH) yields a specific capacitance of 1700 F g-1 at 1 A g-1 with 96% retention after 5000 cycles. The assembled asymmetric supercapacitor exhibits an energy density of 45.93 W h Kg-1 and a power density of 752 W kg-1@1 A g-1.

Diffusion-Mediated Morphological Transformation in Bifunctional Mn2O3/CuO-(VO)3(PO4)2·6H2O for Enhanced Electrochemical Water Splitting.

A strategical approach for morphological transformation and heterojunction formation was utilized to suppress the shortcomings of uni-metal oxide electrocatalysts and enhance their bifunctionality. In situ generation of copper oxide (CuO) over the surface of manganese oxide (Mn2O3) resulted in a morphological transformation from solid spheres to hollow spherical structures due to the ion-exchange diffusion (Kirkendall effect) of Cu ions into Mn2O3 particles. This hollowness resulted in the advancement of the bifunctional electrocatalytic behavior of Mn2O3/CuO (overpotential (η10) of 280 mV for an OER and 310 mV for an HER at a current density of 10 mA/cm2) by virtue of increased exposed surface active sites aiding the adsorption of water molecules on the surface. The increased electrochemical active surface area (ECSA/Cdl = 34 mF/cm2) and reduced charge transfer resistance resulted in the formation of Mn2O3/CuO hollow spheres to achieve an approximately threefold enhancement in the turnover frequency (TOF) compared to the bare Mn2O3. The electrocatalytic efficiency of Mn2O3/CuO was further enhanced by virtue of the faster charge transfer coefficient of two-dimensional (2D) vanadyl phosphate hexahydrate (VOP) sheets deposited over its surface. This boosted the overall water splitting with attained overpotential (η10) values of 190 and 220 mV with Tafel slopes of 60 and 105 mV/decade for an OER and HER, respectively. The morphological transformation and formation of an n-p heterojunction between Mn2O3 and CuO based on their work function (φ) values evaluated from the density functional theory (DFT) calculation and the effect of the VOP overlayer for faster reaction kinetics at the electrolyte interface resulted in an ∼10-fold increment in TOF values compared to the bare counterpart.

Synchronized redox pairs in metal oxide/hydroxide chemical analogues for an efficient oxygen evolution reaction.

A two-step electrodeposition of CoMn2O4 and its chemical analogue CoMn(OH)x directly over Ni-foam yields an excellent water oxidation overpotential of 260 mA cm-2 with a Tafel slope of 29 mV dec-1 and a four-fold increase in turnover frequency. The enhanced efficacy of the composite catalyst is realized through synchronized redox pairs and superior carrier transport.

Physical and electrochemical properties of new structurally flexible imidazolium phosphate ionic liquids.

New structurally flexible 1-methyl- and 1,2-dimethyl-imidazolium phosphate ionic liquids (ILs) bearing oligoethers have been synthesized and thoroughly characterized. These novel ILs revealed high thermal stabilities, low glass transitions, high conductivity and wide electrochemical stability windows up to 6 V. Both the cations and anions of 1-methyl-imidazolium ILs diffuse faster than the ions of 1,2-dimethyl-imidazolium ILs, as determined by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The 1-methyl-imidazolium phosphate ILs showed relatively higher ionic conductivities and ion diffusivity as compared with the 1,2-dimethyl-imidazolium phosphate ILs. As expected, the diffusivity of all the ions increases with an increase in the temperature. The 1-methyl-imidazolium phosphate ILs formed hydrogen bonds with the phosphate anions, the strength of which is decreased with increasing temperature, as confirmed by variable temperature 1H and 31P NMR spectroscopy. One of the representative IL, [EmDMIm][DEEP], presented promising elevated temperature performance as an electrolyte in a supercapacitor composed of multiwall carbon nanotubes and activated charcoal (MWCNT/AC) composite electrodes.

Prediction of COVID-19 Infected Population for Indian States through a State Interaction Network-based SEIR Epidemic Model.

Objective of this present study is to predict the COVID-19 trajectories in terms of infected population of Indian states. In this work, a state interaction network of sixteen Indian states with highest number of infected caseload is considered, based on networked Susceptible-Exposed-Infected-Recovered (SEIR) epidemic model. An intervention term has been introduced in order to capture the effect of lockdown with different stringencies at different periods of time. The model has been fitted using least absolute shrinkage and selection operator (LASSO). Machine learning methods have been used to train the parameters of the model, cross-validate the data, and predict the parameters. The predictions of infected population for each of the sixteen states have been shown using data considered from January 1, 2021 till writing this manuscript on June 25, 2021. Finally, the effectiveness of the model is manifested by the calculated mean error and confidence interval.

Hierarchical FeO(OH)-CoCeV (Oxy)hydroxide as a Water Cleavage Promoter.

The search for a bifunctional electrocatalyst having water cleavage promoting ability along with the operational stability to efficiently generate oxygen and hydrogen could lead to robust systems for applications. These fundamental ideas can be achieved by designing the morphology, tuning the electronic structure, and using dopants in their higher oxidation states. Herein, we have fabricated a binder-free FeO(OH)-CoCeV-layered triple hydroxide (LTH) bifunctional catalyst by a two-step hydrothermal method, in which the nanograin-shaped FeO(OH) coupled with CoCeV-LTH nanoflakes provides more electrocatalytically active sites and enhances the charge-transfer kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The composition-optimized electrocatalyst (FeO(OH)-Co0.5Ce0.05V0.15-LTH) acts as an efficient water cleavage composite by virtue of its favorable oxidation states leading to cyclic redox couples, which yields an overpotential of 53 mV for HER and 227 mV for OER to drive 10 mA/cm2 current density in 1 M KOH with a corresponding Tafel slope of 70 mV/dec for HER and 52 mV/dec for OER. Furthermore, for the overall water splitting reaction, the heterostructure FeO(OH)-Co0.5Ce0.05V0.15-LTH acts as a dual-functional electrocatalyst, which requires a cell voltage of 1.52 V versus RHE to drive 10 mA/cm2 current density.

Hollow cuboidal MnCo2O4 coupled with nickel phosphate: a promising oxygen evolution reaction electrocatalyst.

The growth of hierarchical morphologies of complex metal oxides directly on the substrate is a challenging task. Herein we report a unique hollow-cuboidal MnCo2O4 (h-MCO) morphology that offers insights into the efficient charge-transfer and surface kinetics for the oxygen evolution reaction. h-MCO coupled nickel phosphate under alkaline conditions outperforms the benchmark RuO2.

Phosphorus nitride nano-dots as a versatile and metal-free support for efficient photoelectrochemical water oxidation.

Phosphorus nitride dots (PNDs) are employed as a metal-free and versatile support over a range of metal oxide-based photoanodes for efficient photoelectrochemical (PEC) water oxidation. PNDs have the ability to form various heterojunctions by virtue of their favorable band positions for enhanced charge separation leading to improved photocurrent densities.

Self-Assembly of a [1 + 1] Ionic Hexagonal Macrocycle and Its Antiproliferative Activity.

A unique irregular hexagon was self-assembled using an organic donor clip (bearing terminal pyridyl units) and a complementary organometallic acceptor clip. The resulting metallamacrocycle was characterized by multinuclear NMR, mass spectrometry, and elemental analyses. Molecular modeling confirmed hexagonal shaped cavity for this metallamacrocycle which is a unique example of a discrete hexagonal framework self-assembled from only two building blocks. Cytotoxicity of the Pt-based acceptor tecton and the self-assembled PtII-based macrocycle was evaluated using three cancer cell lines and results were compared with cisplatin. Results confirmed a positive effect of the metallamacrocycle formation on cell growth inhibition.

Coordination-Driven Self-Assembly of Ionic Irregular Hexagonal Metallamacrocycles via an Organometallic Clip and Their Cytotoxicity Potency.

Two new irregular hexagons (6 and 7) were synthesized from a pyrazine motif containing an organometallic acceptor clip [bearing platinum(II) centers] and different neutral donor ligands (4,4'-bipyridine or pyrazine) using a coordination-driven self-assembly protocol. The two-dimensional supramolecules were characterized by multinuclear NMR, mass spectrometry, and elemental analyses. Additionally, one of the macrocycles (6) was characterized by single-crystal X-ray analyses. Macrocycles are unique examples of [2 + 2] self-assembled ensembles that are hexagonal but irregular in shape. These hexagon frameworks require the assembly of only four tectons/subunits. The cytotoxicity of platinum(II)-based macrocycles was studied using various cell lines such as A549 (human lung carcinoma), KB (human oral cancer), MCF7 (human breast cancer), and HaCaT (human skin keratinocyte) cell lines, and the results were compared with those of cisplatin. The smaller macrocycle (7) exhibited a higher cytotoxic effect against all cell types, and its sensitivity was found to be comparable with that of cisplatin for A549 and MCF7 cells. Cell cycle analysis and live propidium iodide staining suggest that the macrocycles 6 and 7 induced a loss of membrane integrity that ultimately might lead to necrotic cell death.

TROVE: a user-friendly tool for visualizing and analyzing cancer hallmarks in signaling networks.

SUMMARY: Cancer hallmarks, a concept that seeks to explain the complexity of cancer initiation and development, provide a new perspective of studying cancer signaling which could lead to a greater understanding of this complex disease. However, to the best of our knowledge, there is currently a lack of tools that support such hallmark-based study of the cancer signaling network, thereby impeding the gain of knowledge in this area. We present TROVE, an user-friendly software that facilitates hallmark annotation, visualization and analysis in cancer signaling networks. In particular, TROVE facilitates hallmark analysis specific to particular cancer types. AVAILABILITY AND IMPLEMENTATION: Available under the Eclipse Public License from: https://sites.google.com/site/cosbyntu/softwares/trove and https://github.com/trove2017/Trove.

First-line antituberculosis drug, pyrazinamide, its pharmaceutically relevant cocrystals and a salt.

A few pyrazinamide (Pyz) cocrystals involving hydroxybenzoic/cinnamic acid derivatives [2,4-dihydroxybenzoic acid (24DHBA); 2,6-dihydroxybenzoic acid (26DHBA); 3,5-dihydroxybenzoic acid (35DHBA) and nutraceutical molecule ferulic acid (FRA)] and the first example of a molecular salt with p-toluenesulfonic acid (pTSA) have been prepared and characterized using various solid-state techniques. A high-temperature cocrystal polymorph of Pyz·FRA has been characterized from the endothermic peaks observed using differential scanning calorimetry. The presence of substituent groups carrying hydrogen bond donors or acceptors and their influence on supramolecular synthon formation has been investigated using a Cambridge Structural Database search. Equilibrium solubility of all the binary complexes of Pyz follows the order of their coformer solubility, i.e. Pyz+·pTSA- > Pyz·35DHBA > Pyz > Pyz·26DHBA > Pyz·24DHBA > Pyz·FRA. A twofold enhancement in solubility of Pyz+·pTSA- molecular salt compared with the parent drug suggests a potential drug formulation for the treatment of tuberculosis.