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Herein, a new and generic strategy has been proposed to introduce uniformly distributed graphitic carbon into the nanostructured metal oxide. A facile and generic synthetic protocol has been proposed to introduce uniformly distributed conducting graphitic carbon into the Co3O4 nanoparticles (Co3O4 NPs@graphitic carbon). The prepared Co3O4 NPs@graphitic carbon has been drop casted onto the portable screen-printed electrode (SPE) to realize its potential application in the individual and simultaneous quantification of toxic Pb(II) and Cd(II) ions present in aqueous solution. The proposed Co3O4 NPs@graphitic carbon-based electrochemical sensor exhibits a wide linear range from 0 to 120 ppb with limit of detection of 3.2 and 3.5 ppb towards the simultaneous detection of Pb(II) and Cd(II), which falls well below threshold limit prescribed by WHO.

The fabrication of an efficient electro-catalyst, made of non-precious metals, for oxygen evolution reaction (OER) is an exciting task. A simple cathodic deposition followed by electrochemical anodic activation has been proposed to prepare a potential electro-catalyst, amorphous nickel oxyhydroxide, on a stainless steel (SS) substrate wherein the whole fabrication procedure completes within a minute. The proposed protocol demonstrates good electrical contact between loosely packed amorphous nickel oxyhydroxide and SS substrate. The experimental results demonstrate cathodic deposition time significantly affect interfacial charge transfer resistance and in turn OER performance. Electrochemical results reveal OER proceeds through the formation of NiO2 intermediate. The amorphous nickel oxyhydroxide@SS fabricated using cathodic deposition time of 40 s followed by anodic activation of 15 s display the low overpotential of 330 mV@25 mA cm−2 (1.56 V vs. RHE) with long-term stability over 70 h.

The potential of silicon-based fluorescent platforms for the detection of trace toxic metal ions was investigated in an aqueous environment. To this aim, silicon chips were first functionalized with amino groups, and fluorescein organic dyes, used as sensing molecules, were then covalently linked to the surface via formation of thiourea groups. The obtained hybrid heterostructures exhibited high sensitivity and selectivity towards copper(II), a limit of detection compatible with the recommended upper limits for copper in drinking water, and good reversibility using a standard metal–chelating agent. The fluorophore–analyte interaction mechanism at the basis of the reported fluorescence quenching, as well as the potential of performance improvement, were also studied. The herein presented sensing architecture allows, in principle, tailoring of the selectivity towards other metal ions by proper fluorophore selection, and provides a favorable outlook for integration of fluorescent chemosensors with silicon photonics technology.

Aluminium/ silicon carbide (Al/SiC) metal matrix composites are widely used in the automotive applications owing to its remarkable tribological properties. In this study, the metal matrix composites with 7.5% SiC (weight proportion) are prepared by stir casting method. To study the influence of process parameters, experiments are designed using L09 orthogonal array. Three parameters, namely sliding speed, load and Sliding Distance, are considered in the present work. The effect of these parameters on friction and wear rate of Al 6061/ SiC metal matrix composites are analyzed. Testing is conducted to access the wear rate and friction. Taguchi grey relation analysis is used to estimate the optimum process parameters. An Analysis of Variance (ANOVA) is conducted to identify significant and non-significant factors. The load applied is found to be the most significant factor. The optimal process parameters are found to be the sliding distance 500 m, load 10 N and sliding speed 4 m/s. The R2 value of the Taguchi grey-based model is found to be 99.44 percentage. Confirmation tests are conducted to verify the optimized results. Metallurgical analysis confirms the defect-free Al/Sic composites with improved tribological properties.

An ultrasound-assisted extraction (leaching) method of valuable metals from discarded lithium-ion batteries (LiBs) is reported. Mild organic citric or acetic acids were used as leaching agents for a more environmentally-friendly recovery of the lithium, nickel, cobalt, and manganese from the discharged and crushed lithium nickel-manganese-cobalt oxide (NMC) LiBs. The extraction was performed with the presence/absence of continuous ultrasound (US) energy supplied by a 110 W ultrasonic bath. The effect of temperature (30–70 °C), reducing agent concentration (H2O2: 0–2.0 vol%), as well as choice of specific acid on the metal dissolution were investigated. The US leaching decreased the leaching time by more than 50% and improved the leached percentage of Li, Mn, Co, and Ni due to the local heat and improved mass transfer between solid and liquid interfaces in the process. The X-ray diffraction results of residues from the US leaching further confirmed an improved dissolution of the crushed layered NMC structure, resulting in the significant improvement of the leached amounts of the valuable metals. Furthermore, it is demonstrated that using citric acid eliminated the need of additional reducing agents and suppressed the dissolution of copper (Cu) due to its inhibitor effect on the Cu surface, i.e. compared with using acetic acid as leaching reagent. Overall, it is shown that recovery of the battery metals can be facilitated and carried out in a more energy-efficient manner at low temperatures (50 °C) using ultrasound to improve metal ions mass transportation in the residue layers of the NMC during the organic acid leaching.

In this research article, the FSW tool parameters for welding the dissimilar aluminium AA7075-T651 and AA6061 alloy were optimized by implementing the Taguchi method. The FSW parameters related to the tool such as tool offset, pin profile of tool and tilt angle of tool were taken into account for the experimental work. The optimal FSW parameters were confirmed through the confirmation experimental run. ANOVA analysis revealed that the tilt angle of tool is the most dominating factor with contribution percentage of 45.85% and other parameters like tool pin profile involved 40.27% and tool offset involved 12.36% for improving the tensile properties of the FSWed dissimilar AA7075-T651 and AA6061 joint. SEM image of tensile fractured surfaces revealed that most of the specimens were failed due to ductile mode of fracture.

A greenhouse experiment was conducted at College of Agriculture V.C. Farm, Mandya using CRD design with ten treatments and three replications with an objective to study the “Effect of urea modified hydroxyapatite nano fertilizer (UHA) on quality of tomato under greenhouse condition”. Whereas, highest TSS content (5.80 0 Brix) was recorded in the treatment T9 which received 100% Nitrogen-Urea + 1.00% UHA spray and significantly highest lycopene content was recorded in treatment T9 (16.85 mg 100g-1). Highest ascorbic acid content of tomato plant was observed in the treatment T8 (68.04 mg 100g-1) with the application of 100% Nitrogen-Urea + 0.50 per cent UHA spray, which showed significant difference with all the treatments. Increased quality parameters in tomato was attributed to increased growth and yield parameters which is due to slow and sustained release of nitrogen, phosphorus and calcium from urea modified hydroxyapatite nano fertilizer.

The search of new multifunctional cathode materials, with new crystal structures and compositions, for lithium ion battery is extremely important to mitigate the drawbacks associated with the current electrode materials used in rechargeable lithium ion batteries. In this paper, orthovanadate family CrVO4 has been identified and investigated as a new cathode material for high-rate and high-capacity lithium ion battery for the first time. A solution-based effective and versatile synthetic protocol has been proposed to synthesize CrVO4 nanoparticles. Physical characterizations reveal that the prepared CrVO4 consists of uniform and discreet nanoparticles of crystallite size ~ 19 nm with widespread pore diameter, enhanced conductivity and surface area. The prepared CrVO4 nanoparticles have been evaluated as a potential cathode material for lithium ion batteries, wherein the experimental results demonstrate enhanced lithium storage with high rate-capability and cyclability. The experimental results reveal that the proposed CrVO4 is working through a partial conversion reaction mechanism.

Herein, a new cathode material, Mn2V2O7, for lithium-ion batteries is identified. A simple chemical method is proposed to synthesize newly identified Mn2V2O7 material for large scale production. The synthesis of nanosized manganese vanadate in high yield with improved electrochemical performance toward lithium-ion battery applications is of fundamental and technological advancement. The newly identified Mn2V2O7 holds a large reversible capacity of 242 mAh/g at 0.2 C rate with 82% of capacitance retention after 1442 cycles and thereby makes it suitable for lithium-ion battery fabrication. This long-term cycling is the highest reported for Mn2V2O7 to the best of our knowledge.

Chemoselective reduction of imines to secondary amines is catalyzed efficiently by tethered and untethered, half-sandwich ruthenium N-heterocyclic carbene (NHC) complexes at room temperature. The untethered Ru-NHC complexes are more efficient as catalysts for the reduction of aldimines and ketimines than the tethered complexes. Using the best untethered complex as a catalyst, electronic and steric demands on the reaction was probed using a series of imines. Chemoselectivity of the catalyst towards imine reduction was tested by performing inter and intramolecular competitive reactions in a variety of ways. The catalyst exhibits a very high TON and TOF under anaerobic conditions. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Tethered and untethered ruthenium half-sandwich complexes were synthesized and characterized spectroscopically. X-ray crystallographic analysis of three untethered and two tethered Ru N-heterocyclic carbene (NHC) complexes were also carried out. These RuNHC complexes catalyze transfer hydrogenation of aromatic ketones in 2-propanol under reflux, optimally in the presence of (25 mol %) KOH. Under these conditions, the formation of 2-3 nm-sized Ru0 nanoparticles was detected by TEM measurements. A solid-state NMR investigation of the nanoparticles suggested that the NHC ligands were bound to the surface of the Ru nanoparticles (NPs). This base-promoted route to NHC-stabilized ruthenium nanoparticles directly from arene-tethered ruthenium-NHC complexes and from untethered ruthenium-NHC complexes is more convenient than previously known routes to NHC-stabilized Ru nanocatalysts. Similar catalytically active RuNPs were also generated from the reaction of a mixture of [RuCl2 (p-cymene)]2 and the NHC precursor with KOH in isopropanol under reflux. The transfer hydrogenation catalyzed by these NHC-stabilized RuNPs possess a high turnover number. The catalytic efficiency was significantly reduced if nanoparticles were exposed to air or allowed to aggregate and precipitate by cooling the reaction mixtures during the reaction.

International audience; The synthesis, structural, photophysical characterization and theoretical studies on homo/heteroleptic neutral 2D layered coordination polymers (CPs), obtained by combining the erbium(III) ion with chlorocyananilates (ClCNAn) and/or tetrafluoroterephthalates (F4BDC) linkers, are herein reported. The structure of the heteroleptic Er III-based CP, formulated as [Er2(ClCNAn)2(F4BDC)(DMSO)6]n (1) is also reported. 1 crystallizes in the triclinic P-1 space group and the structure consists of neutral 2D layers formed by Er III ions linked through the two linkers oriented in such a way that the neighboring 2D layers are eclipsed along the a axis, leading to parallelogram-like cavities. Photophysical measurements highlight the prominent role of chlorocyananilate linkers as optical antennas toward lanthanide ions, while wave-function theory analysis supports the experimental findings providing evidence for the effect of ligand substitution on the luminescence properties of homo/heteroleptic 2D CPs.

Nowadays, the development of nanostructures of oxide-based materials gained significant research interest owing to their new merits and avenues to design better electrodes for lithium-ion battery. It is well known that vanadium and vanadium-based oxide materials have high theoretical capacity but the practical applications are limited mainly due to the fast capacity fading, resulting from the structural collapse, upon cycling and poor electronic conductivity. In this paper, we demonstrate the fabrication of mesoporous vanadium-based oxide with nanostructures, which significantly improved the capacity fading upon cycling. A simple and generic synthetic protocol has been proposed to synthesize highly porous AlV3O9 using aluminum nitrate and ammonium vanadate with the assistance of sucrose. It is found that the decomposition of surface-adsorbed sucrose during the course of AlV3O9 preparation creates homogeneously distributed mesopores. The prepared porous AlV3O9 has been used to fabricate positive electrode for lithium rechargeable battery where high discharge capacity of 240 mAhg−1 was achieved at 0.2 C rate, which is comparable to the best reported results of vanadium-based positive electrodes. The characteristic features are 240 mAhg−1 capacity and ~ 100% columbic efficiency, demonstrating porous AlV3O9 as a promising cathode material for high-power batteries.

A Raman study on Zinc-substituted Cobalt ferrites, with different Zn(II) contents in each sample of formula: CoFe₂O₄ (1), Zn0.30Co0.70Fe2.00O₄ (2), Zn0.46Co0.54Fe2.02O₄ (3), Zn0.53Co0.47Fe2.02O₄ (4) is reported. These samples show the same crystallite size (∼6 nm), particle size (∼7 nm) and particle size distribution (∼20%) and they have been synthesized through heating up surfactant-assisted thermal decomposition of metalorganic precursors. The effect of Zn(II) substitution in the cationic distribution is investigated by using the known metal-oxygen vibrational modes in tetrahedral and octahedral sites. The presence of Zn(II) metal ion is determined through the band at 150 cm-1 (T2g(1) phonon mode), which is not present in the pure Co-ferrite, a blue-shift of the Eg vibrational mode depending on Zn(II)/Co(II) cationic distribution and a shoulder at ∼250 cm-1, which appears when zinc enters in the structure, and a broadening and a red-shift in the A1g phonon mode is observed in Raman spectra of 2-4 samples. Interestingly the latter represents a potential key probe to monitor the Zn(II) presence in Zn-substituted Co-ferrites.

Ruthenium half-sandwich complexes ligated to chiral 2-oxazolidinethiones or 2-thiozolidinethiones in the reduction of N-benzylideneaniline using silyl hydrides as reductants has been examined. The chemoselective reduction of imines takes place under mild conditions to afford the corresponding amines in nearly quantitative yield. Mechanistic studies indicate that dissociation of the ancillary ligands generate the active catalyst in all the complexes studied, which is the same species generated by Ru(p-cymene)(Cl)(2)](2) under the reaction conditions. This results in the formation of a single catalytic species irrespective of the starting half-sandwich complex. Detailed mechanistic studies involving trapping of intermediates, in situ studies using mass spectrometry and NMR spectroscopy were carried out using the active catalyst generated by Ru(p-cymene)(Cl)(2)](2). The mechanism of the reaction is dependent on the number of the hydrogen atoms in the reducing silane. The reaction proceeds via Gade-Hoffman pathway or Zheng-Chan pathway when a dihydro or trihydrosilane is the reductant. However, the use of a monohydrosilane, leads to longer reaction times presumably due to a change in the reaction pathway.

© 2019 Hydrogen Energy Publications LLC We present a facile methodology for the synthesis of a novel 2D-MoS2, graphene and CuNi2S4 (MoS2-g-CuNi2S4) nanocomposite that displays highly efficient electrocatalytic activity towards the production of hydrogen. The intrinsic hydrogen evolution reaction (HER) activity of MoS2 nanosheets was significantly enhanced by increasing the affinity of the active edge sites towards H+ adsorption using transition metal (Cu and Ni2) dopants, whilst also increasing the edge sites exposure by anchoring them to a graphene framework. Detailed XPS analysis reveals a higher percentage of surface exposed S at 17.04%, of which 48.83% is metal bonded S (sulfide). The resultant MoS2-g-CuNi2S4 nanocomposites are immobilized upon screen-printed electrodes (SPEs) and exhibit a HER onset potential and Tafel slope value of – 0.05 V (vs. RHE) and 29.3 mV dec−1, respectively. These values are close to that of the polycrystalline Pt electrode (near zero potential (vs. RHE) and 21.0 mV dec−1, respectively) and enhanced over a bare/unmodified SPE (– 0.43 V (vs. RHE) and 149.1 mV dec−1, respectively). Given the efficient, HER activity displayed by the novel MoS2-g-CuNi2S4/SPE electrochemical platform and the comparatively low associated cost of production for this nanocomposite, it has potential to be a cost-effective alternative to Pt within electrolyser technologies.

The performance of the cathode materials can be enhanced significantly by manipulating the surface properties through a nano-structuring. Porous ZrV2O7 is synthesized, in the present study, by a facile one-step solution-based method wherein the proposed method and the ZrV2O7 have the advantages of less preparation time, low cost, small crystallite size, porous structure, and good electrical conductivity, which dramatically improves the electrochemical properties. The porous ZrV2O7 electrode exhibits the conductivity of 0.57 × 10−6 S/cm, which is close to the conductivity of the traditional cathode materials LiMn2O4 (10−6 S cm−1). The galvanostatic charge-discharge results reveal that the porous ZrV2O7 delivers excellent discharge capacity of 159 mAh g−1 and 126 mAh g−1 at C/10 and 1 C (C = charge and discharge) rate, respectively, besides excellent reversibility.

Nano particulate metal oxides gained significant research interest in recent years for various applications with the intension of exploring enhanced properties of miniaturization. In this research work, nickel tungstate nanoparticles (NiWO4 nanoparticles) were successfully synthesized via a simple and efficient sucrose-nitrate decomposition method. The synthesized nanoparticles were characterized using various analytical techniques such as PXRD, SEM, TEM, BET measurements and FTIR. Transmission electron microscope images reveals the nearly spherical shaped nanoparticles of average particle size 15–35 nm. Photoluminescence characteristics of synthesized NiWO4 nanoparticles were investigated at room temperature. Further, the prepared nanoparticles were utilized as glassy carbon electrode modifier for trace level electrochemical sensing of toxic mercury present in water samples. The electrochemical behavior of mercury(II) ions at modified electrode interface has been studied by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). The results illustrate that, the proposed modified GCE sensor exhibits linearity between the concentration range 10–600 nM with the limit of detection 2.25 nM based on 3σ method for mercury(II) ions.

Nano sized zinc ferrite (ZnFe2O4) particles have been synthesized by a simple solution combustion method and its electrochemical sensing application has been reported after modifying the glassy carbon electrode with thin film of zinc ferrite. The nanoparticles have been characterized by FTIR, XRD, BET, FESEM and TEM techniques to ascertain the particle size and its surface morphology. It has been used as an electrochemical sensing tool in the simultaneous measurement of lead and cadmium ions at trace level by differential pulse anodic stripping voltammetry (DPASV). All the experimental variables have been optimized and it has been utilized in real sample analysis. The sensor exhibited wide linearity in the concentration range 10–130 ppb with detection limits of 1.12 and 2.52 ppb for lead and cadmium metal ions, respectively.

The method of photoplethysmography (PPG) detailed in Chapters 1 and 2 gained enormous prominence due to the development of pulse oximetry. In pulse oximetry, the fact that hemoglobin bound with oxygen (called oxyhemoglobin) and hemoglobin without oxygen (deoxy-hemoglobin or reduced hemoglobin) absorb/reflect light differently is exploited in ascertaining, noninvasively, oxygen saturation in arterial blood. Most pulse oximeters that are in existence today use a couple of PPGs obtained using red and infrared wavelength light sources and calculate oxygen saturation in arterial blood using the red and IR PPGs and an empirical equation. This chapter details the development of pulse oximetry. It describes in detail a couple of novel methods of oxygen saturation calculation using the red and IR PPGs. The methods presented here do not need any calibration to be performed.

© 2020 Hydrogen Energy Publications LLC We describe a novel synthesis technique for the production of graphitic carbon functionalized Co3O4 (G/Co3O4), which involves the rapid decomposition of cobalt nitrate in the presence of citric acid. Upon immobilization of the G/Co3O4 upon Screen-Printed macroElectrodes (G/Co3O4-SPEs) the G/Co3O4-SPEs were found to exhibit remarkable electrocatalytic properties towards the Oxygen Reduction Reaction (OER). A detailed investigation has been carried out on the influence that the graphitization of the citric acid has, during the course of preparation of Co3O4, upon the ability of the G/Co3O4 to catalyse the OER within alkaline conditions (1.0 M KOH). The graphitization of citric acid ensures the uniform distribution of Co3O4 and enhanced conductivity with maximal exposure of active sites, which are the key parameters to delivering enhanced electrochemical activity. The G/Co3O4-SPEs exhibits an overpotential of 304 mV (recorded at 10 mA cm−2), a Tafel slope of 110 mV dec−1 and remain stable in its signal output (achievable current density) at varying temperatures (5–50 °C), and after 10 h of chronoamperometry in 1.0 M KOH. The G/Co3O4-SPE's OER activity was found to be superior to that of bulk and nano Co3O4. The results exhibited within this study will enable production of high-performance and environmentally benign electrocatalysts towards the OER for use within water splitting devices.

Manganese tungstate nanoparticles (NPs) were successfully synthesized via a simple and cost effective citric acid assisted solution combustion method. Rietveld refinement of PXRD pattern indicates the formation of pure wolframite phase of manganese tungstate. Transmission electron microscope (TEM) analyses confirm the spherical shaped nanoparticles with average particle size ranging from 12 to 26 nm. The ultra-light combustion derived manganese tungstate NPs exhibits mesoporous nature with the estimated band gap 2.9 eV. The synthesized NPs were found to be an excellent electrode modifier for the simultaneous detection of Pb(II), Cd(II), Cu(II) and Hg(II) ions at nanomolar (nM) concentration. The present electrochemical sensor exhibits wide linearity of 10 – 500 nM with limit of detection based on 3σ method is 3.3, 3.5, 2.9 and 3.1 nM for Pb(II), Cd(II), Cu(II) and Hg(II) respectively. Additionally, room temperature photoluminescence emission spectrum exhibits an intense band at 445 nm that can be attributed to 1A1 ground-state to the high vibration 1T2 energy levels of distorted [WO6] octahedral groups.

Transition metal homeostasis is necessary to sustain life. First row transition metals act as cofactors within the cell, performing vital functions ranging from DNA repair to respiration. However, intracellular metal concentrations exceeding physiological requirements may be toxic. In E. coli, the YqjH flavoprotein is thought to play a role in iron homeostasis. YqjH is transcriptionally regulated by the ferric uptake regulator and a newly discovered regulator encoded by yqjI. The apo-form of YqjI is a transcriptional repressor of both the yqjH and yqjI genes. YqjI repressor function is disrupted upon binding of nickel. The YqjI N-terminus is homologous to nickel-binding proteins, implicating this region as a nickel-binding domain. Based on function, yqjI and yqjH should be renamed Ni-responsive Fe-uptake regulator (nfeR) and Ni-responsive Fe-uptake flavoprotein (nfeF), respectively. X-ray Absorption Spectroscopy was employed to characterize the nickel binding site(s) within YqjI. Putative nickel binding ligands were targeted by site-directed mutagenesis and resulting variants were analyzed in vivo for repressor function. Isothermal titration calorimetry and competitive binding assays were used to further quantify nickel interactions with wild-type YqjI and its mutant derivatives. Results indicate plasticity in the nickel binding domain of YqjI. Residues C42 and C43 were found to be required for in vivo response of YqjI to nickel stress, though these residues are not required for in vitro nickel binding. We propose that YqjI may contain a vicinal disulfide bond between C42 and C43 that is important for nickel-responsive allosteric interactions between YqjI domains.

Transfer hydrogenation of aromatic ketones catalyzed by eight cyclometallated ruthenium half-sandwich complexes, including three new complexes, was examined. The catalytic process was studied using different ratios of substrate to base and base to catalyst and using a deuterated reductant. Optimum conditions for catalysis were shown to be in the presence of higher amounts of base in refluxing isopropanol. Under these conditions, the complexes were reduced in situ to give Ru(0) nanoparticles invisible to the naked eye. The nanoparticles were characterized by TEM, DLS and XPS. The catalytic transfer hydrogenation, under conditions in which nanoparticles were generated, was found to be far greater than the transfer hydrogenation by the molecular catalyst. Complete characterization of the three new complexes, including the X-ray crystallographic characterization of these complexes was carried out.

The Fe2V4O13 is considered as one of the most promising cathode materials for next generation secondary batteries owing to its high specific capacity and energy density. However, the synthesis of pure Fe2V4O13 is difficult because of complicated Fe2O3–V2O5 phase diagram. Thus, in this paper, a facile solution combustion method which operates relatively at low temperature was proposed to synthesize impurity free Fe2V4O13 nanoparticles. The selection of fuel, oxidizer/fuel (O/F) ratio and temperature on the formation of impurity free Fe2V4O13 has been investigated. The optimum temperature and time for the preparation of impurity free Fe2V4O13 nanoparticles was found to be 350 °C/1 h. The synthesized Fe2V4O13 nanoparticles exhibit monoclinic phase with high surface area of 36 m2/g. The prepared Fe2V4O13 nanoparticles were tested as cathode material for lithium secondary battery and charge discharge results show that the 154 mAh·g−1 is retained after 50 cycle.

Despite its high photoluminescence (PL) performance, cadmium silicate (CdSiO3) as a luminescence host has not been comprehensively studied. In this article, we present a simple solution combustion method for the synthesis of Na+ and K+ co-doped Cd0.95Eu0.05SiO3 phosphor. The influence of charge compensators such as Na+ and K+ on the luminescence performance of Cd0.95Eu0.05SiO3 was systematically investigated. X-ray diffraction results confirms that Cd0.95Eu0.05SiO3:Na+ and Cd0.95Eu0.05SiO3: K+ phosphors are in monoclinic phase and found to increase in the crystallinity as concentration of Na+ and K+ increases. Scanning electron microscope images exhibit agglomerated particles having nanoscale dimension. PL excitation spectra of Cd0.95Eu0.05SiO3, Cd0.95Eu0.05SiO3:Na+ and Cd0.95Eu0.05SiO3:K+ phosphors exhibit excitation peaks in the ultra-violet (UV), near-UV and far-UV regions. Very interestingly, the intensity of PL emission was found to increase with increase in the Na+ and K+ concentrations. The optimum co-dopant concentrations were found to be 7 mol% for both phosphors. The emission intensity of 613 nm peak was enhanced by a factor of 1.78 and 1.66 with Na+ and K+ co-doping respectively. The enhancement in PL emission has been explained by the mechanism of charge compensation and phosphor crystallinity. The PL results confirms that these phosphors could be potential materials for optoelectronic applications.

Design of efficient and stable bifunctional electro-catalysts made of non-precious metals is a field of intense research in order to bring hydrogen production from laboratory to industrial scale. TiO2 is considered as electrochemically inactive may be due to the poor surface reactivity. Manipulating the electronic structure and stability of TiO2 to work under realistic conditions is crucial for the optimal production of hydrogen and oxygen. Herein, new class of titanium compound, LiTiPO4F, has been identified as a water splitting electrocatalyst. The resulted new mesoporous LiTiPO4F has been used as an efficient bifunctional electro-catalyst, to catalyse HER and OER, in alkaline medium, for the first time. The proposed LiTiPO4F catalyst demonstrated an ultrahigh electrocatalytic activity and stability towards HER and OER. The proposed mesoporous LiTiPO4F delivers ηOER, 100 mA cm−2 = 310 mV with Tafel slope of 93 mV dec−1 and ηHER, -100 mA cm−2 = -290 mV with small Tafel slope of 48 mV dec−1, revealing good OER/HER activity.

Water electrolysis powered by renewable energy sources to produce green hydrogen is a very promising and sustainable alternative to fossil fuels, as well as one of the best approaches for significantly reducing carbon footprints and controlling pollution. In this study, novel hybrid non-stoichiometric nanocomposite Co3S4/Co0.85Se electrocatalyst materials were synthesized using a simple and one-pot eco-friendly hydrothermal method. The as-prepared samples were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) for structural features. Crystalline phases of Co3S4, Co0.85Se, and mixed phases in the hybrid samples were confirmed through XRD. Uniformly distributed agglomerated nanoparticles (30-80 nm) of Co3S4, clearly distinguishable nanoaggregates (20-90 nm) of Co0.85Se, and nanoflakes covered with nanoparticles (30-150 nm) of Co3S4/Co0.85Se were confirmed by FESEM. The synergistic effects of the hybrid nanocomposite due to the combination of Co3S4 (containing two different oxidation states of cobalt) and non-stoichiometric Co0.85Se, was investigated towards the oxygen evolution reaction (OER). The electrocatalytic studies confirmed that the Co3S4/Co0.85Se electrocatalyst exhibited a low overpotential of 362 mV @ +30 mA.cm−2 towards the OER in an alkaline solution in comparison with Co3S4 and Co0.85Se electrocatalysts. Furthermore, a low overpotential of 1.59 V at a high current density and a high electrochemical active surface area (ECSA) of 210 cm2 was achieved due to the combined effects of chemical coupling between the Co3S4 and Co0.85Se. Chronoamperometric studies revealed excellent stability of the hybrid nanocomposite samples with negligible changes in the overpotential, even after 30 hours of testing. The synergetic effect of cobalt chalcogenides due to the nanoscale interaction was confirmed by the enhanced electrocatalytic activity.

Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen species, is a challenging task. We report a BODIPY-based luminescence ON reagent for detection of HNO in aqueous solution and in live RAW 264.7 cells, based on the soft nucleophilicity of the phosphine oxide functionality toward HNO. The probe shows high selectivity to HNO over other reactive oxygen/nitrogen and sulfur species. Luminescence properties of the BODIPY-based chemodosimetric reagent make it an ideal candidate for use as a reagent for super-resolution structured illumination microscopy. The viability of the reagent for biological in vivo imaging application was also confirmed using Artemia as a model.

A series of two-dimensional (2D)-layered coordination polymers (CPs) based on the heterosubstituted anilate ligand ClCNAn2- derived from 3-chloro-6-cyano-2,5-dihydroxybenzoquinone and DyIII are reported. By changes in the synthetic methods (layering technique, solvothermal or conventional one-pot reactions) and conditions (solvent, concentration, etc.), different types of 2D extended networks could be prepared and structurally characterized. Compounds 1 and 1', two polymorphs with the formula [Dy2(ClCNAn)3(DMSO)6]n·(H2O)x [x = 7 (1), 0 (1')], were prepared by a conventional one-pot reaction and recrystallized at different concentrations. Compound 2, formulated as [Dy2(ClCNAn)3(DMF)6]n, was prepared by a layering technique, while compound 3, formulated as {(Me2NH2)2[Dy2(ClCNAn)4(H2O)2]·(DMF)2·(H2O)5}n, was obtained by a solvothermal method. Compounds 1 and 2 are neutral 2D CPs of the ClCNAn2- ligand and DyIII ions, while 3 presents 2D anionic layers of [Dy2(ClCNAn)4(H2O)2]2- alternating with cationic layers of Me2NH2+ ions. These compounds show very diverse networks, with compound 1 forming 2D (8,3) and (4,3) topology with eight- and four-membered rings with square cavities, 1' and 2, respectively, a 2D (6,3) topology with six-membered rings (a rectangular cavity for 1' and a regular hexagonal cavity for 2), and 3 a 2D (4,4) topology with distorted square cavities. In this respect, 1 and 1' represent the first examples of polymorphism in the family of anilate-based CPs. Thermal analysis measurements (differential scanning calorimetry and thermogravimetry) show an exothermic polymorphic transformation from the kinetically stable 1' phase to the thermodynamically stable phase 1. The magnetic behavior of 1-3 very likely indicates depopulation of the mJ levels, while the presence of weak antiferromagnetic coupling between the DyIII centers mediated by the anilate bridge cannot be excluded.

Glutathione Peroxidase activity in whole blood is well correlated with the Selenium (Se) levels in cattle hence can be used effectively to assess the supply of Se to farm animals. In this study, Se status of cattle from five different geographic regions of Sri Lanka were assessed based on glutathione peroxidase (GSH-Px) activity. The GSH-Px activity was determined in whole blood samples collected from 80 cattle from 31 different farms in five districts viz. Kandy, Anuradhapura, Batticoloa, Trincomalee and Jaffna using photometric method. Mean GSH-Px activity was found to be 825, 1239, 1039, 849 and 1307 μkat L−1 in above districts, respectively while the reference value was considered as 665.4 μkat L−1. Among the studied animals, insufficient Se levels were detected in 50%, 17%, 9%, 27% and 5%, respectively, from above districts. Kruskal Wallis test indicated a significant variation among the sampled locations with respect to the GSH-Px activity (p = 0.001). Selenium content in pasture and water collected from studied locations varied from 6.0 to 554 μg kg−1 and

The simple mixing of copper(I) compounds with bisphosphines led to the formation of copper(I) complexes with chelating or bridging bisphosphines. A wide vasriety of mononuclear, dinuclear, and polynuclear complexes result. The bisphosphine plays a key role in determining the nuclearity, coordination number, and structure of the complexes formed. Significant deviations from the expected tetrahedral or trigonal coordination geometries are often dictated by the substituents on the phosphorus. The plasticity of the coordination sphere of copper(I) permits distortions from ideal geometries. Limitless variation of substituents on phosphorus, including the possibility of having chiral phosphines, has played a key role in the utility of these copper(I) complexes. Although catalytic reactions promoted by copper(I) complexes do not involve redox transformations, they are useful in chiral transformations.

Substituted selenodiazoles (piazselenols) were used as ligands to synthesize organometallic ruthenium(II) piano-stool complexes using the precursors (eta(6)-cymene)RuX2 (where x = Cl, Br and I). Analytical data suggested that two (eta(6)-cymene)Ru motifs were present per ligand in the solid state. However, H-1 and Se-77 NMR in DMSO solution confirmed the dissociation of the selenodiazole ligand from the ruthenium center. Interestingly, selenodiazole with naphthalene substitutes possess excellent photophysical properties. It showed strong red fluorescence (576 nm) when excited at visible region (488 nm) and was found suitable for use as an imaging agent in HCT 116 cells. Among all ligands examined, only the nitro substituted selenodiazole showed potent anticancer activity against the A2780 cell line.

Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments. Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline.

Herein, the Taguchi L-9 orthogonal technique has been employed to design the optimised conditions (sulfur source, temperature, reaction time and surfactant) for the preparation of nickel sulfide polymorphs using hydrothermal method. The experimental results demonstrate the temperature dependant phase transition of NiS → Ni3S4 → NiS2 and the prepared nickel sulfide polymorphs exhibit distinctive morphologies of sugar cubes, spherical apple, rose type, aggregated stones, and tubular bacteria type structures. The effect of morphology and crystalline structure on oxygen evolution reaction (OER) has been investigated for the first time where the OER performance follows the order: NiS > NiS2 > Ni3S4. Among the various morphologies of NiS, and NiS2, the order of OER performance is as follows: NiS(sugar-cubes) > NiS(agglomerated stone particles) > NiS(apple shaped) and NiS2(aggregated stoneparticles) > NiS2(rose type) > NiS2(tubular bacteria) shaped nanostructure.

Metal nanoparticles exhibit unusual properties different from metal complexes and heterogeneous metals and hence draw considerable attention for applications in catalysis, magnetism, medicine, optoelectronics, and sensors. Herein we present an overview of the recent progress in catalysis using soluble ruthenium nanocatalysts (colloids). These nanocatalysts have been widely used for catalyzing the hydrogenation of various substrates particularly arenes due to the milder conditions and the unique selectivities achieved compared to those exhibited by classical heterogeneous catalysts. Ru(0) colloids have been also examined for catalyzing many different reactions including transfer hydrogenation, dehydrogenation, coupling reactions and C H activation, etc. Although in many of these transformations Ru(0) nanocatalysts exhibit high activities, there remain several challenges such as recovery of the soluble catalyst, catalysis by leached molecular clusters, and asymmetric catalysis with high enantioselectivity.

Lead telluride ( PbTe) with indium ( In) and bismuth ( Bi) as micrometer sized secondary phases dispersed throughout the bulk has been prepared by matrix encapsulation method. In and Bi are not found to substitute in PbTe as shown by Rietveld and room temperature Raman studies but are present as secondary phases. Increased values of temperature dependent electrical resistivity and Seebeck coefficient show the effect of interfaces on electronic transport. As expected, thermal conductivity is found to reduce on addition of secondary phases due to a reduced electronic contribution, further confirming that electron scattering at interfaces is more important than phonon scattering in such systems for thermoelectric properties. However, due to the reduction in the power factor of the In and Bi added samples from that of the parent PbTe, the overall thermoelectric figure of merit ( zT) does not increase beyond that of PbTe, for which the highest value of 0.7 is obtained at 778 K.

The reaction of Ru(eta(6)-cymene)Cl-2](2) and PPh2Cl in the ratio 1:2 gives a stable Ru(h(6)-cymene) Cl-2(PPh2Cl)] complex. Attempts to make the cationic Ru(eta(6)-cymene)Cl(PPh2Cl)(2)]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of Ru(eta(6)-cymene)Cl-2(PPh2OH)]. Attempts to make a phosphinite complex by reacting Ru(eta(6)-cymene)Cl-2](2) with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give Ru(eta(6)-cymene)Cl-2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor.

The first hyperpolarizability (beta) of a series of half-sandwich Ru complexes with a mercaptobenzothiazole ligand bearing a halogen atom substitution in the para-position has been investigated by hyper-Rayleigh scattering and quantum chemical calculations. The heterocyclic ligand with a bromine atom in the para position makes it a very good donor and charge flows to the Ru center enhancing the beta value of the complex by a factor of 2 compared to the complex with the ligand without the halogen substitution. The resonance (+R) and the inductive (-I) effects exerted by the halogen atom in the para position push electrons in opposing directions in the complex. For the Br and Cl atoms the resonance effect dominates which enables the ligand to donate electrons to the metal center thereby increasing the hyperpolarizability whereas for the fluorine atom, the inductive effect is dominant which reduces the charge flow to the metal and the hyperpolarizability drops even below that of the unsubstituted ligand. This unprecedented halogen atom effect on beta of metal complexes is reported. (C) 2015 Elsevier By. All rights reserved.

Organoarsenicals such as the methylarsenical methylarsenate (MAs(V)) and aromatic arsenicals including roxarsone (4-hydroxy-3-nitro-benzenearsenate or Rox(V)) have been extensively used as an herbicide and growth enhancers in animal husbandry, respectively. They undergo environmental degradation to more toxic inorganic arsenite (As(III)) that contaminates crops and drinking water. We previously identified a bacterial gene (arsI) responsible for aerobic demethylation of methylarsenite (MAs(III)). The gene product, ArsI, is an Fe(II)-dependent extradiol dioxygenase that cleaves the carbon–arsenic (C–As) bond in MAs(III) and in trivalent aromatic arsenicals. The objective of this study was to elucidate the ArsI mechanism. Using isothermal titration calorimetry, we determined the dissociation constants and ligand-to-protein stoichiometry of ArsI for Fe(II), MAs(III), and aromatic phenylarsenite. Using a combination of methods including chemical modification, site-directed mutagenesis, and fluorescent spectroscopy, we demonstrated that amino acid residues predicted to participate in Fe(II)-binding (His5–His62–Glu115) and substrate binding (Cys96–Cys97) are involved in catalysis. Finally, the products of Rox(III) degradation were identified as As(III) and 2-nitrohydroquinone, demonstrating that ArsI is a dioxygenase that incorporates one oxygen atom from dioxygen into the carbon and the other to the arsenic to catalyze cleavage of the C–As bond. These results augment our understanding of the mechanism of this novel C–As lyase.

The C-terminal repeat domain of staphylocoagulase that is secreted by the S. aureus is believed to play an important role interacting with fibrinogen and promotes blood clotting. To study this interaction by NMR, full assignment of each amide residue in the HSQC spectrum was required. Despite of the short sequence of the repeat construct, the HSQC spectrum contained a substantial amount of overlapped and exchange broadened resonances, indicating little secondary or tertiary structure. This caused severe problems while using the conventional, amide based NMR method for the backbone assignment. With the growing interest in small apparently disordered proteins, these issues are being faced more frequently. An alternative strategy to improve the backbone assignment capability involved carbon direct detection methods. Circumventing the amide proton detection offers a larger signal dispersion and more uniform signal intensity. For peptides with higher concentrations and in combination with the cold carbon channels of new cryoprobes, higher fields, and sufficiently long relaxation times, the disadvantage of the lower sensitivity of the 13C nucleus can be overcome. Another advantage of this method is the assignment of the proline backbone residues. Complete assignment with the carbon-detected strategy was achieved with a set of only two 3D, one 2D, and a HNCO measurement, which was necessary to translate the information to the HSQC spectrum.

Mulberry being a C3 crop responsive to carbon, climate change in the form of elevated CO2 coupled with increased temperature would be helpful for crop but it gets altered in presence of herbivore. The eCO2 and temperature favoured growth and development of mulberry only in terms of quantity which was evidenced by accelerated growth of more plant height, leaves, leaf area index, leaf yield and plant biomass. Biochemical analysis of mulberry showed a lot of changes in it, wherein, the chlorophyll, carbon and carbon based compounds viz., tannins, phenols, total sugars, carbohydrates significantly increased in eCO2 as compared to aCO2 treatments. On the contrary, nitrogen (N) and N-based compounds viz., proteins decreased in eCO2 compounds which in turn altered C:N ratio.