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For the first time, we report a facile one pot aqueous method for support-free Pd85Pt15 nano-porous structures (NPoS) synthesis from PdMn nano-alloys at ambient conditions. A hierarchical approach was successfully employed through a simple “self-settlement” process with descending amounts of carbon to carbon-free electro-catalysts to improve catalyst utilization and avoid carbon degradation during fuel cell operating conditions. Pd85Pt15 NPoS exhibits enhanced methanol resistive oxygen reduction reaction (ORR) activity owing to the presence of highly active and unique surface PdPt islands compared to HiSPEC Pt/C catalysts. Accelerated durability tests of the support-free PdPt NPoS show enhanced durability in harsh acidic environment (1.0 N H2SO4) compared to HiSPEC Pt/C and DOE 2017–2020 durability target. Preliminary direct methanol fuel cell studies using hierarchically derived Pd85Pt15 NPoS variants were performed at ultra-low Pt content. The effects of carbon content and catalyst layer thickness on fuel cell activities are well discussed.

We report an enhanced power conversion efficiency (PCE) of 11.7% ± 0.2 and a fill factor (FF) of 71% for dye-sensitized solar cells (DSSC) with an active area of 0.16 cm2 after modifying the TiO2photoanode with size-selective (ca. 2 nm) N,F,S-codoped graphene quantum dots (NFS-GQDs) that exhibit a photoluminescence quantum yield (PLQY) of 70%. An upward shift in the Fermi level has been observed, perhaps responsible for the improved performance along with the possibility of preventing the back electron transfer from TiO2. Mott Schottky analysis indicates a shift (52 mV)in the flat band potential, which is directly related to the Voc of the system. Detailed characterization (IPCE, TCSPC etc) indicates the important role of hetero atoms in facilitating the enhanced performance. Thus, our results suggest that the incorporation of size controlled, hetero atom doped GQDs can enhance the efficiency of DSSCs enabling more opto-electronic applications.

Organic Light Emitting Diode (OLED) has major applications in the field of displays, lighting and visible light communication. Due to the advantages of low cost, light weight, low power and high efficiency, flexible organic light emitting diode have attracted the interest of researchers all over the World. Flexible OLEDs are considered to be the best suitable candidate for next generation lighting devices. In this research, a new flexible and transparent substrate with an average transmittance of 60-70% in the visible region (300-700nm) is synthesized with the help of organic materials such as tetraphenylphosphonium modified lithium saponite (TPP-LiSA), Synthetic Saponite (SA) and N, N-dimethylformamide (DMF). The as-synthesized substrate exhibits refractive index as close as glass which makes this substrate to be used for flexible displays. Characteristics such as extinction coefficient (k), absorption of the synthesized substrate are also calculated.

Graphitic carbon continues to dominate as the choice anode material in lithium-ion batteries despite its theoretical specific capacity of 372 mAhg −1 . Tailored forms of graphite with higher practical capacities should, therefore, be of interest to the industry. This paper reports the production of a kish graphitic anode material from polyvinyl chloride by simultaneous carbonization of the polymer and dissolution of the resulting carbon in an iron melt to produce a supersaturated solution of carbon in iron, and subsequent precipitation of the carbon as graphite upon cooling. Our study presents a process for converting non-biodegradable plastic wastes that litter our surroundings into a technologically useful product. The new material exhibits a first-cycle reversible capacity of 444 mAhg −1 and sustains at least 200 cycles at C/10 rate before its capacity drops below 372 mAhg −1 .

Fabrication of quasi solid state dye sensitized solar cell with a stable gel electrolyte employing poly(ethylene oxide) (PEO)-poly(ethylene glycol) (PEG) is reported in this paper. PEO-PEG with either one of alkali iodides (LiI or NaI or KI), 1,2-dimethyl-3-propyl imidazolium iodide (DMPI), 4-tertbutylpyridine (TBP) and iodine in acetonitrile were used for the gel electrolyte preparation. The ionic conductivity and the triiodide diffusion coefficient of the gel electrolytes were measured by Electrochemical Impedance Spectroscopy. The photoconversion efficiency of gel state DSSC with NaI was found to be 5.4% at 100 mW/cm 2 with AM 1.5 Gfilter. When nanocrystalline TiO 2 was used as the filler in the gel electrolyte, the photoconversion efficiency was found to be increased up to 6.3%. The quasi solid state DSSC retained its initial value for 600 hours aging under ambient conditions.

White light emitting alkali metal ion co-doped single host lattice phosphors Sr 2.955 B 2 O 6 :0.02Ce 3+ , 0.005Eu 2+ , 0.02A + [A=Li, Na and K] were synthesized by high temperature solid state reaction. The synthesized phosphors were characterized by powder X-ray diffraction and Fourier transform infrared spectroscopic techniques. The optical properties were studied using diffuse reflectance UV–vis reflectance spectroscopy and photoluminescence (PL) spectroscopy. The role of Ce 3+ as a sensitizer of Eu 2+ was found from PL excitation results. The PL white light emission depends on the nature of co-doped alkali metal ion charge compensator.

Electrochemical properties of FeNbO 4 as a lithium insertion anode material were studied with a view to understand structure–property relationships. Orthorhombic and monoclinic polymorphs of FeNbO 4 were synthesized and characterized by powder X-ray diffraction and laser Raman spectroscopy. Possible redox reactions, as deciphered from cyclic voltammograms, suggest the structural similarity between orthorhombic and monoclinic polymorphs upon lithium insertion. A coating of carbon led to a remarkable improvement in the electrochemical performance of monoclinic FeNbO 4 . The coated material exhibited an average reversible capacity of 125.5 mAh g −1 . The material also sustained hundreds of charge/discharge cycles and exhibited good rate capability. Upon coating with carbon, the monoclinic FeNbO 4 transformed into FeNb 2 O 6 . The conversion and stability were confirmed by powder XRD and laser Raman studies of carbon-coated material before and after 450 cycles. The in situ conversion of FeNbO 4 into FeNb 2 O 6 during carbon coating was further supported by EPR studies in which the absence of signal for the carbon-coated material indicated conversion of Fe 3+ to Fe 2+ . Our study reveals the possibility of exploring potential materials in the Fe–Nb–O system and enhancing their performance as anode materials for lithium-ion batteries.

Chelating terpolymer resin was synthesized from anthranilic acid and 2-amino pyridine with formaldehyde to remove the heavy metal ions present in the solutions. The synthesized terpolymer resin was characterized by spectral techniques such as FTIR, NMR (1H and 13C) and elemental analysis to elucidate the structure of the resin. The physico-chemical parameters have also been evaluated for the terpolymer resin. The surface morphology of the terpolymer resin without the metal ion uptake and with the incorporation of the metal ion was examined by scanning electron microscopy. The chelation ion-exchange property of the terpolymer resin was evaluated by batch equilibrium method for specific metal ions viz. Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Pb2+. The study was extended to three variations such as evaluation of metal ion uptake in presence of various electrolytes in different concentrations, evaluation of the distribution of metal ion uptake at different pH ranges and evaluation of the rate of metal ion uptake at different time intervals. The adsorption isotherm was evaluated by means of Langmuir and Freundlich isotherm models. The order of the kinetics was also determined and the resin follows first order kinetics which shows that physisorption may be involved in the ion-exchange process. From the results, it was observed that the terpolymer resin acts as an excellent cation-exchanger. Compared to the commercially available phenolic and polystyrene resins, the synthesized terpolymer resin showed an excellent ion-exchange capacity with the selected metal ions.

2-Amino-6-nitro-benzothiazole and thiosemicarbazide with formaldehyde (BTF) terpolymer was synthesized by the condensation polymerization technique. The elemental analysis and physico-chemical parameters of the terpolymer were measured. This chelation terpolymer was characterized by infrared, electronic and nuclear magnetic resonance ( 1 H & 13 C NMR) spectral studies. The molecular weight of the terpolymer was determined by gel permeation chromatography (GPC). Surface analysis of the terpolymer was analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) method. The thermal stability of the terpolymer was analyzed by thermogravimetric analysis (TGA). The cation-exchange property of the terpolymer was determined by batch equilibrium method with the effect of pH, contact time and electrolytes. The reusability of the resin was also studied to estimate the effectiveness of the terpolymer resin.

This paper presents in brief the formulation for lateral and longitudinal dynamics associated with the separation and pull out of an ongoing functional stage from the spent stage of a multistage launch vehicle using separation motors as jettisoning system. Taguchi method is employed to understand the influencing parameters in the separation process. It is possible to minimize the number of Monte-Carlo simulations (MCS) by Taguchi's orthogonal array. Statistical analysis has been carried out to identify the probability distribution function (PDF) for reliability and safety assessment of the stage separation system. The tolerances on the pull out time, relative velocity, lateral gap and longitudinal clearances between the separating bodies are taken into account while examining the non-occurrence of collision between the separating bodies. Lateral gap/dynamic clearance between stages are found to be very vital from collision aspects. This study clearly demonstrates the applicability of Taguchi method to capture the essential Monte-Carlo simulation results in the stage separation process. The method of approach followed in this study will be useful to understand the dynamic behavior of the separating bodies during the stage separation process of multistage launch vehicles.

Polyol mediated synthesis for the preparation of tungsten trioxide and titanium doped tungsten trioxide has been reported. The reaction was carried out using chlorides of tungsten and titanium in diethylene glycol medium and water as the reagent for hydrolysis at 190 deg. C. Formation of a blue coloured dimensionally stable suspension of the precursor materials was observed during the course of the reaction. The particle sizes of the precursor materials were observed to be around 100 nm. The precursor materials were annealed to give tungsten trioxide and titanium doped tungsten trioxide. The precursor materials were characterised using TGA/DTA, FT-IR, optical spectra, SEM, TEM and powder XRD methods. It was observed that the doping of titanium could be effected at least up to 10% of Ti in WO{sub 3}. The TGA/DTA studies indicated that WO{sub 3-x}.H{sub 2}O is the dominant material that formed during the polyol mediated synthesis. The XRD data of the annealed samples revealed that the crystalline phase could be manipulated by varying the extent of titanium doping in the tungsten trioxide matrix.

In this paper a M X / G ( a , b )/1 queueing system with multiple vacations, setup time with N -policy and closedown times is considered. On completion of a service, if the queue length is ξ , where ξ a , then the server performs closedown work. Following closedown the server leaves for multiple vacations of random length irrespective of queue length. When the server returns from a vacation and if the queue length is still less than ‘ N ’, he leaves for another vacation and so on, until he finds ‘ N ’ ( N > b ) customers in the queue. That is, if the server finds at least ‘ N ’ customers waiting for service, then he requires a setup time ‘ R ’ to start the service. After the setup he serves a batch of ‘ b ’ customers, where b ⩾ a . Various characteristics of the queueing system and a cost model with the numerical solution for a particular case of the model are presented.

This paper presents in brief the formulation used for the studies of lateral and longitudinal dynamics associated with separation and pull out of an ongoing functional stage from the spent stage of a multistage launch vehicle using retro rockets as jettisoning system. A fourth-order Runge-Kutta method is employed to solve the governing nonlinear differential equations of motion to obtain the state vectors of the separating bodies. A statistical method is adapted to account for the off nominal design parameters of the bodies undergoing separation and the jettisoning system. The tolerances in magnitude of the pull out time, relative velocity, lateral gap and longitudinal clearances between the separating bodies were used to find out the nonoccurrence of collision between the separating bodies. This procedure helps in designing and adapting a suitable jettisoning system to achieve collision free separation of multistage launch vehicle stages.

Yttrium oxide doped with trivalent europium has been prepared by self-propagating high temperature (SPHT) synthesis, also known as combustion synthesis, with nitrogen-based fuels. The materials synthesized have been characterized by X-ray diffraction, scanning electron microscopy, and luminescent emission spectroscopy. Crystallite size, powder density, and photoluminescent-emission intensity/efficiency are found to depend on the fuels used. The phosphor products were sintered with and without sintering aids. The results obtained are discussed with respect to the processing method employed.

Several covalently linked bisporphyrin systems, free-base (H 2 P---H 2 P), hybrid bisporphyrins (Zn---H 2 P) and Zn(II) dimers (ZnP---ZnP) and their 1:1 molecular complexes with sym 1,3,5-trinitrobenzene have been investigated by optical absorption and emission, and magnetic resonance spectroscopic methods. In these systems, two porphyrin units are linked singly through one of the meso aryl groups via ether linkages of variable length. The bisporphyrins cooperatively bind a molecule of a π-acceptor; 1,3,5-trinitrobenzene (TNB). The binding constant values vary with interchromophore separation. Maximum binding is observed in the bisporphyrin bearing a two-ether covalent linkage. It is found that TNB quenches the fluorescence of the two porphyrine units in a selective manner. It is suggested that a critical distance between the two porphyrin units is necessary for the observance of maximum cooperative intermolecular binding with an acceptor.

A supramolecular host—guest assembly based on zeolite YMHCF (M  Ni, Co) is examined electrochemically. Using well-known metal hexacyanoferrate (MHCF) redox chemistry in response to alkali metal cations, revealed by cyclic voltammetric “signatures”, we present the first results on the effects of the zeolite medium and confirm the intrazeolitic presence of MHCF complexes.

Anodic oxidation of 1′,8′-dimethyl- and other 1′,8′-disubstituted a.c -biladiene salts affords novel cyclized products. In addition to porphyrin, an unconjugated macrocyclic intermediate product resulting from oxidadve cyclizatfon during porphyrin synthesis is isolated, structurally identified, and characterized with regard to its spectroscopy, electrochemical behavior and chemical reactivity. The formation of a novel homoporphyrin from a 1′-ethoxycarbonylmethy-8′-(2-methoxycarbonylethyl)- a,c -biladiene salt is also briefly discussed.