The Synthesis of Highly Active Iridium(I) Complexes and their Application in Catalytic Hydrogen Isotope Exchange

A series of robust iridium(I) complexes bearing a sterically encumbered N‐heterocyclic carbene ligand, alongside a phosphine ligand, has been synthesised and investigated in hydrogen isotope exchange processes. These complexes have allowed isotope incorporation over a range of substrates with the use of practically convenient deuterium and tritium gas. Moreover, these active catalysts are capable of isotope incorporation to particularly high levels, whilst employing low catalyst loadings and in short reaction times. In addition to this, these new catalyst species have shown flexible levels of chemoselectivity, which can be altered by simple manipulation of preparative approaches. Furthermore, a number of industrially‐relevant drug molecules has also been labelled, including the sulfonamide containing drug, Celecoxib. Alongside detailed NMR experiments, initial mechanistic investigations have also been performed, providing insight into both substrate binding energies, and, more importantly, relative energies of key steps in the mechanistic cycle as part of the overall exchange process.

     

Border-hunting optimization for mobile agent-based intrusion detection with deep convolutional neural network

The sensor nodes, which are available in the wireless sensor networks (WSN), are equipped with sensing abilities, and communication. Several domains require the sensor nodes to be arranged in aggressive surroundings, in which observing malicious activities within the sensor network. Therefore, the present research proposes the border-hunting optimization-based deep CNN (BHO-DCNN) for the mobile agent (MA)-based intrusion detection in WSN. The importance of the research relies on the BHO-DCNN model for identifying the intrusion available in the network is established by integrating the optimization with its features through a deep classifier for detection in a precise manner. The algorithm follows the communal hierarchy, surrounding, group hunting, and prey attacking, which provides an enhanced rate of convergence in the method of detection. The analysis is achieved through the database IDS 2018 Intrusion CSVs depending on the performance like delay, alive nodes, normalized energy, as well as throughput. The obtained number of alive nodes through the developed BHO-DCNN algorithm is 45, end-to-end delay is 0.2572 ms, normalized energy is 0.1622 J, as well as throughput, is 0.3125% for nodes 50 at the populate rate of 100, respectively.     

Thermodynamic investigation of the MOCVD of copper films from<Emphasis Type="Italic">bis</Emphasis>(2,2,6,6-tetramethyl-3,5-heptadionato)copper(II)

Equilibrium concentrations of various condensed and gaseous phases have been thermodynamically calculated, using the free energy minimization criterion, for the metalorganic chemical vapour deposition (MOCVD) of copper films usingbis(2,2,6,6-tetramethyl-3,5-heptadionato)copper(II) as the precursor material. From among the many chemical species that may possibly result from the CVD process, only those expected on the basis of mass spectrometric analysis and chemical reasoning to be present at equilibrium, under different CVD conditions, are used in the thermodynamic calculations. The study predicts the deposition of pure, carbon-free copper in the inert atmosphere of argon as well as in the reactive hydrogen atmosphere, over a wide range of substrate temperatures and total reactor pressures. Thin films of copper, grown on SiO₂/Si(100) substrates from this metalorganic precursor by low pressure CVD have been characterized by XRD and AES. The experimentally determined composition of CVD-grown copper films is in reasonable agreement with that predicted by thermodynamic analysis.     

Anomalous high pressure behaviour in nanosized rare earth sesquioxides

We report Raman spectroscopic studies of the nanosized rare earth sesquioxides, namely yttrium sesquioxide (Y(2)O(3)), gadolinium sesquioxide (Gd(2)O(3)) and samarium sesquioxide (Sm(2)O(3)), under high pressure. The samples were characterized using x-ray diffraction, Raman spectroscopy and atomic force microscopy at atmospheric pressures. Y(2)O(3) and Gd(2)O(3) were found to be cubic at ambient, while Sm(2)O(3) was found to be predominantly cubic with a small fraction of monoclinic phase. The strongest Raman peaks are observed at 379, 344 and 363?cm(-1), respectively, for Y(2)O(3), Sm(2)O(3) and Gd(2)O(3). All the samples were found to be nanosized with 50-90?nm particle sizes. The high pressures were generated using a Mao-Bell type diamond anvil cell and a conventional laser Raman spectrometer is used to monitor the pressure-induced changes. Y(2)O(3) seems to undergo a crystalline to partial amorphous transition when pressurized up to about 19?GPa, with traces of hexagonal phase. However, on release of pressure, the hexagonal phase develops into the dominant phase. Gd(2)O(3) is also seen to develop into a mixture of amorphous and hexagonal phases on pressurizing. However, on release of pressure Gd(2)O(3) does not show any change and the transformation is found to be irreversible. On the other hand, Sm(2)O(3) shows a weakening of cubic phase peaks while monoclinic phase peaks gain intensity up to about a pressure of 6.79?GPa. However, thereafter the monoclinic phase peaks also reduce in intensity and mostly disordering sets in which does not show significant reversal as the pressure is released. The results obtained are discussed in detail.     

Comparison of corrosion performance of various conversion coatings on magnesium alloy using electrochemical techniques

Comparative studies on some of the important chemical conversion coatings, namely, phosphate–permanganate, galvanic black anodizing, dichromate treatment, and micro arc oxidized and modified acid fluoride anodizing on magnesium alloy AZ31B have been conducted. The surface morphology and composition of the coatings were examined through SEM and EDX techniques. Corrosion resistances of these coatings were compared using electrochemical impedance spectroscopy (EIS) and linear polarization studies. The corrosion resistances of the coatings investigated were found to be according to the order as follows: modified acid fluoride > micro arc oxidized phosphate > micro arc oxidized silicate > dichromate > galvanic black anodizing > phosphate-permanganate > bare magnesium.     

InGaAs-InGaN Wafer-Bonded Current Aperture Vertical Electron Transistors (BAVETs)

In this paper, we report the fabrication process and direct-current (DC) characteristics of a wafer-bonded heterostructure-based vertical transistor. It comprises an In_0.53Ga_0.47As/In_0.52Al_0.48As/In_0.53Ga_0.47As field-effect transistor wafer-bonded to a Ga-polar In_0.1Ga_0.9N/GaN template. In the DC-bias operation of this device, the current conduction is initially confined lateral to the InGaAs channel and then flows vertically through a conductive aperture defined in the InGaN/GaN layers. The narrow aperture is isolated by ion-implanted current blocking layer (CBL) regions. The I _d–V _ds characteristics of the device demonstrate transistor-like behavior. Design optimizations have been applied to the implant and doping conditions of the InGaN/GaN layers to eliminate the leakage paths through the CBL while simultaneously obtaining unhindered current conduction through the aperture of the device.     

Supercapacitor with superior electrochemical properties derived from symmetrical manganese oxide-carbon fiber coated with polypyrrole

A supercapacitor electrode comprising conducting polypyrrole (PPy) coated on manganese oxide-carbon fiber (CNFMnO₂) was successfully synthesized using electrospinning, followed by carbonization and in-situ polymerization. A non-uniform distribution of PPy on the surface of CNFMnO₂ was observed via FESEM analysis. The chemical bonding of CNFMnO₂/PPy and the valence state of manganese were revealed via FTIR, Raman spectroscopy, XRD and XPS measurements. CNFMnO₂/PPy composite possessed high specific capacitance and specific energy of 315.80 Fg^?1 and 13.68 Wh/kg, respectively. In addition, good electrochemical reversibility was proven upon CNFMnO₂/PPy even at higher sweep rate (5–200 mV/s). Moreover, this one-dimensional electrode achieved an excellent long-term cycling stability (82.46%) over 2000 CV cycles with low charge transfer resistance (4.61 Ω). The modification of CNFMnO₂/PPy contributes to good synergistic effects among the material which improve the electrochemical behavior of manganese oxide-based fiber composite for future supercapacitor.     

Influence of frequency and temperature on dielectric and electrical properties of Ca-substituted barium iron niobate

This paper presents the dielectric and electrical behavior of (Ba_1-xCa_x)(Fe_1/2Nb_1/2)O₃ (x?=?0.0, 0.2, 0.6, 1.0) solid solutions. The dielectric and electrical properties were investigated with respect to variation in temperature (25–250?°C) and frequency (10–970?kHz) using impedance analyzer. This study suggests that the relative permittivity increased with increase in Ca content up to x?=?0.2 and then decreased for higher Ca concentration. Dielectric anomaly observed in ?_r-T plots is frequency dependent which indicates that the relaxation in the system is due to electrons trapped in oxygen vacancies The occurrence of maxima of Z" and M" at different frequencies indicate the presence of Non Debye type relaxation in the studied materials. The purposed materials are potential candidate for multilayer capacitor applications.     

Adsorption behavior of dyes from aqueous solution using agricultural waste: modeling approach

The development of efficient and ecofriendly biosorbent for the removal of dyes is a priority in regions where human health is directly affected by elevated dye concentrations. Biosorption of dyes on shelled Moringa oleifera seed powder (SMOS) was investigated for the removal of methylene blue and Congo red from aqueous solution. Sorption studies led to the standardization of the optimum conditions: dye concentration (25 mg/l), contact time (40 min), particle size (105 μM), and volume (200 ml) at pH 6.5 and 2.5 for the removal of methylene blue (90.27 %) and Congo red (98.52 %). A single layer artificial neural network (ANN) model was developed to simulate the process and predict the removal efficiency of SMOS for the removal of dyes. Different ANN architectures were tested by varying network topology, resulting into an excellent agreement between the experimental data and the predicted values. The Levenberg–Marquardt algorithm was found best of BP algorithms with a minimum mean squared error for training and cross validation as 1.89951E?09 and 0.145001313, respectively.     

Active layer modification of commercial nanofiltration membrane using CuBTC/PVA matrix for improved surface and separation characteristics

The present study proposes a facile route for the modification of commercial nanofiltration (NF) polymeric membrane by embedding metal organic framework (MOF) via dip coating. A mixed membrane matrix comprising of copper benzene-1,3,5-tricarboxylate (CuBTC) and polyvinyl alcohol (PVA) served as the new active layer. The obtained topography, functional group, and surface elemental analysis elucidated the presence of heterogeneous phase and the distribution of the MOF on the membrane. The dip coating well supported the modification through excellent adhesion. The water wettability of the modified membrane displayed a positive correlation with CuBTC loading in the PVA polymer matrix. Permeation and separation characteristics of the resultant membranes were investigated by retaining protein and carbohydrates from synthetic dairy wastewater (SDWW). The permeability rate of modified samples increased to 43% as compared to the commercial NF membrane. A significant improvement in the rejection rate of carbohydrate from 61% to 87% and protein from 88% to 94% was achieved. Membrane Fouling was found to be much lesser for the modified samples. The study highlights the potential of CuBTC as filler material for enhancing the separation characteristic of established NF membrane.