Interface-dominated Growth of a Metastable Novel Alloy Phase

A new \textit{D0$_{23}$} metastable phase of Cu$_3$Au is found to grow at the interfaces of Au/Cu multilayers deposited by magnetron sputtering. The extent of formation of this novel alloy phase depends upon an optimal range of interfacial width primarily governed by the deposition wattage of the dc-magnetron used. Such interfacially confined growth is utilized to grow a $\sim$ 300 nm thick Au/Cu multilayer with thickness of each layer nearly equal to the optimal interfacial width which was obtained from secondary ion mass spectrometry (SIMS) data. This growth technique is observed to enhance the formation of the novel alloy phase to a considerable extent. SIMS depth profile also indicates that the mass fragment corresponding to Cu$_3$Au occupies the whole film while x-ray diffraction (XRD) shows almost all the strong peaks belonging to the \textit{D0$_{23}$} structure. High resolution cross-sectional transmission electron microscopy (HR-XTEM) shows the near perfect growth of the individual layers and also the lattice image of the alloy phase in the interfacial region. Vacuum annealing of the alloy film and XRD studies indicate stabilization of the \textit{D0$_{23}$} phase at $\sim$ 150$^{\circ}$C. The role of interfacial confinement, the interplay between interfacial strain and free energy and the hyperthermal species generated during the sputtering process are discussed.Comment: Accepted in Journal of Materials Researc

Lepton flavor violating Higgs boson decay at e(+)e(-) colliders

We estimate the smallest branching ratio for the Higgs decay channel h -> mu tau, which can be probed at an e(+)e(-) collider, and compare it with the projected reach at the high-luminosity run of the LHC. Using a model-independent approach, Higgs production is considered in two separate cases. In the first case, hWW and hZZ couplings are allowed to be scaled by a factor allowed by the latest experimental limits on hWW and hZZ couplings. In the second case, we have introduced higher-dimensional effective operators for these interaction vertices. Keeping BR(h -> mu tau) as a purely phenomenological quantity, we find that this branching ratio can be probed down to approximate to 2.69 x 10(-3) and approximate to 5.83 x 10(-4), respectively, at the 250 GeV and 1000 GeV runs of an e(+)e(-) collider.Peer reviewe

A Systems Approach to a One‐Pot Electrochemical Wittig Olefination Avoiding the Use of Chemical Reductant or Sacrificial Electrode

An unprecedented one‐pot fully electrochemically driven Wittig olefination reaction system without employing a chemical reductant or sacrificial electrode material to regenerate triphenylphosphine (TPP) from triphenylphosphine oxide (TPPO) and base‐free in situ formation of Wittig ylides, is reported. Starting from TPPO, the initial step of the phosphoryl P=O bond activation proceeds through alkylation with RX (R=Me, Et; X=OSO2CF3 (OTf)), affording the corresponding [Ph3POR]+X− salts which undergo efficient electroreduction to TPP in the presence of a substoichiometric amount of the Sc(OTf)3 Lewis acid on a Ag‐electrode. Subsequent alkylation of TPP affords Ph3PR+ which enables a facile and efficient electrochemical in situ formation of the corresponding Wittig ylide under base‐free condition and their direct use for the olefination of various carbonyl compounds. The mechanism and, in particular, the intriguing role of Sc3+ as mediator in the TPPO electroreduction been uncovered by density functional theory calculations.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"TU Berlin, Open-Access-Mittel – 202

Crystalline Copper Selenide as a Reliable Non‐Noble Electro(pre)catalyst for Overall Water Splitting

Electrochemical water splitting remains a frontier research topic in the quest to develop artificial photosynthetic systems by using noble metal‐free and sustainable catalysts. Herein, a highly crystalline CuSe has been employed as active electrodes for overall water splitting (OWS) in alkaline media. The pure‐phase klockmannite CuSe deposited on highly conducting nickel foam (NF) electrodes by electrophoretic deposition (EPD) displayed an overpotential of merely 297 mV for the reaction of oxygen evolution (OER) at a current density of 10 mA cm−2 whereas an overpotential of 162 mV was attained for the hydrogen evolution reaction (HER) at the same current density, superseding the Cu‐based as well as the state‐of‐the‐art RuO2 and IrO2 catalysts. The bifunctional behavior of the catalyst has successfully been utilized to fabricate an overall water‐splitting device, which exhibits a low cell voltage (1.68 V) with long‐term stability. Post‐catalytic analyses of the catalyst by ex‐situ microscopic, spectroscopic, and analytical methods confirm that under both OER and HER conditions, the crystalline and conductive CuSe behaves as an electro(pre)catalyst forming a highly reactive in situ crystalline Cu(OH)2 overlayer (electro(post)catalyst), which facilitates oxygen (O2) evolution, and an amorphous Cu(OH)2/CuOx active surface for hydrogen (H2) evolution. The present study demonstrates a distinct approach to produce highly active copper‐based catalysts starting from copper chalcogenides and could be used as a basis to enhance the performance in durable bifunctional overall water splitting.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"TU Berlin, Open-Access-Mittel – 202

Enabling Iron‐Based Highly Effective Electrochemical Water‐Splitting and Selective Oxygenation of Organic Substrates through In Situ Surface Modification of Intermetallic Iron Stannide Precatalyst

A strategy to overcome the unsatisfying catalytic performance and the durability of monometallic iron‐based materials for the electrochemical oxygen evolution reaction (OER) is provided by heterobimetallic iron–metal systems. Monometallic Fe catalysts show limited performance mostly due to poor conductivity and stability. Here, by taking advantage of the structurally ordered and highly conducting FeSn2 nanostructure, for the first time, an intermetallic iron material is employed as an efficient anode for the alkaline OER, overall water‐splitting, and also for selective oxygenation of organic substrates. The electrophoretically deposited FeSn2 on nickel foam (NF) and fluorine‐doped tin oxide (FTO) electrodes displays remarkable OER activity and durability with substantially low overpotentials of 197 and 273 mV at 10 mA cm−2, respectively, which outperform most of the benchmarking NiFe‐based catalysts. The resulting superior activity is attributed to the in situ generation of α‐FeO(OH)@FeSn2 where α‐FeO(OH) acts as the active site while FeSn2 remains the conductive core. When the FeSn2 anode is coupled with a Pt cathode for overall alkaline water‐splitting, a reduced cell potential (1.53 V) is attained outperforming that of noble metal‐based catalysts. FeSn2 is further applied as an anode to produce value‐added products through selective oxygenation reactions of organic substrates.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"TU Berlin, Open-Access-Mittel – 202

Traumatic globe luxation: A case report

Globe luxation is a rare clinical event. Most of the cases are usually traumatic, although spontaneous globe luxation has also been reported. The majority of the posttraumatic cases are usually associated with the injury or fracture of the bony orbit. We report here a case of globe luxation that occurred per se without any injury to the orbital or maxillo-facial bony structures

Knowledge Based database of arm-muscle and activity characterization during load pull exercise using Diagnostic Electromyography (D-EMG) Signal.

In this paper, Diagnostic Electromyography (D-EMG) signal interpretation of human arm towards characterization of arm-muscle interaction during various arm movements has been discussed. EMG signals from four important arm muscle (i.e., Bicepsbracci, Tricepsbracci, brachioradialis, and lateral deltoids) are recorded clinically during five different arm movements (i.e., Extension of the forearm, flexion of elbow joint, pronation of forearm, shoulder abduction, and Wrist flexor stretch) under load condition (a load of 2 Kg & 4 Kg maintained during experimental arm movement), the recorded D-EMG signals are properly enveloped within a range of 5–100 Hz and quantized within a proper sampling frequency range to produce a knowledge-based database of muscle activity. In addition, correlation of muscle activity and Power spectral density (PSD) analysis has been carried out towards muscle process discriminating during various arm actions