Room-Temperature-Processable Highly Reliable Resistive Switching Memory with Reconfigurability for Neuromorphic Computing and Ultrasonic Tissue Classification

Reversible metal-filamentary mechanism has been widely investigated to design an analog resistive switching memory (RSM) for neuromorphic hardware-implementation. However, uncontrollable filament-formation, inducing its reliability issues, has been a fundamental challenge. Here, an analog RSM with 3D ion transport channels that can provide unprecedentedly high reliability and robustness is demonstrated. This architecture is realized by a laser-assisted photo-thermochemical process, compatible with the back-end-of-line process and even applicable to a flexible format. These superior characteristics also lead to the proposal of a practical adaptive learning rule for hardware neural networks that can significantly simplify the voltage pulse application methodology even with high computing accuracy. A neural network, which can perform the biological tissue classification task using the ultrasound signals, is designed, and the simulation results confirm that this practical adaptive learning rule is efficient enough to classify these weak and complicated signals with high accuracy (97%). Furthermore, the proposed RSM can work as a diffusive-memristor at the opposite voltage polarity, exhibiting extremely stable threshold switching characteristics. In this mode, several crucial operations in biological nervous systems, such as Ca²⁺ dynamics and nonlinear integrate-and-fire functions of neurons, are successfully emulated. This reconfigurability is also exceedingly beneficial for decreasing the complexity of systems—requiring both drift- and diffusive-memristors.     

Highly selective sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene)/poly(ether sulfone) blend proton exchange membranes for direct methanol fuel cells

Proton exchange membranes (PEMs) based on blends of poly(ether sulfone) (PES) and sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene) (sPVdF‐co‐HFP) were prepared successfully. Fabricated blend membranes showed favorable PEM characteristics such as reduced methanol permeability, high selectivity, and improved mechanical integrity. Additionally, these membranes afford comparable proton conductivity, good oxidative stability, moderate ion exchange capacity, and reasonable water uptake. To appraise PEM performance, blend membranes were characterized using techniques such as Fourier transform infrared spectroscopy, AC impedance spectroscopy; atomic force microscopy, and thermogravimetry. Addition of hydrophobic PES confines the swelling of the PEM and increases the ultimate tensile strength of the membrane. Proton conductivities of the blend membranes are about 10^?3 S cm^?1. Methanol permeability of 1.22 × 10^?7cm² s^?1 exhibited by the sPVdF‐co‐HFP/PES10 blend membrane is much lower than that of Nafion‐117. AFM studies divulged that the sPVdF‐co‐HFP/PES blend membranes have nodule like structure, which confirms the presence of hydrophilic domain. The observed results demonstrated that the sPVdF‐co‐HFP/PES blend membranes have promise for possible usage as a PEM in direct methanol fuel cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43907.     

Characterisation of sol–gel method synthesised MgZnFe2 O4 nanoparticles and its cytotoxic effects on breast cancer cell line,MDA MB‐231 in vitro

In this study, nanocrystalline magnesium zinc ferrite nanoparticles were successfully prepared by a simple sol–gel method using copper nitrate and ferric nitrate as raw materials. The calcined samples were characterised by differential thermal analysis/thermogravimetric analysis, Fourier transform infrared spectroscopy and X‐ray diffraction. Transmission electron microscopy revealed that the average particle size of the calcined sample was in a range of 17–41 nm with an average of 29 nm and has spherical size. A cytotoxicity test was performed on human breast cancer cells (MDA MB‐231) and (MCF‐7) at various concentrations starting from (0 µg/ml) to (800 µg/ml). The sample possessed a mild toxic effect toward MDA MB‐231 and MCF‐7 after being examined with MTT (3‐[4, 5‐dimethylthiazol‐2‐yl]‐2, 5 diphenyltetrazolium bromide) assay for up to 72 h of incubation. Higher reduction of cells viability was observed as the concentration of sample was increased in MDA MB‐231 cell line than in MCF‐7. Therefore, further cytotoxicity tests were performed on MDA MB‐231 cell line.Inspec keywords: sol‐gel processing, nanoparticles, nanofabrication, magnesium compounds, zinc compounds, toxicology, biological organs, cancer, cellular biophysics, nanomedicine, calcination, differential thermal analysis, Fourier transform infrared spectra, X‐ray diffraction, transmission electron microscopy, particle size, organic compoundsOther keywords: sol‐gel method, cytotoxic effects, breast cancer cell line, MDA MB‐231 in vitro, nanocrystalline magnesium zinc ferrite nanoparticles, copper nitrate, ferric nitrate, raw materials, calcined samples, differential thermal analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, average particle size, cytotoxicity testing, human breast cancer cells, mild toxic effect, 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyltetrazolium bromide) assay, cell viability, MCF‐7, MDA MB‐231 cell line, size 17 nm to 41 nm     

Green synthesis of copper oxide nanoparticles and mosquito larvicidal activity against dengue,zika and chikungunya causing vector Aedes aegypti

In the present study, high purity copper oxide nanoparticles (NPs) were synthesised using Tridax procumbens leaf extract. Green syntheses of nano‐mosquitocides rely on plant compounds as reducing and stabilising agents. Copper oxide NPs were characterised using X‐ray diffraction (XRD) analysis, Fourier transform infrared (FT‐IR), Field‐emission scanning electron microscopy with energy dispersive spectroscopy, Ultraviolet–visible spectrophotometry and fluorescence spectroscopy. XRD studies of the NPs indicate crystalline nature which was perfectly matching with a monoclinic structure of bulk CuO with an average crystallite size of 16 nm. Formation of copper oxide NPs was confirmed by FT‐IR studies and photoluminescence spectra with emission peaks at 331, 411 and 433 nm were assigned to a near‐band‐edge emission band of CuO in the UV, violet and blue region. Gas chromatography–mass spectrometry studies inferred the phytochemical constituents of the leaf extract. Larvicidal activity of synthesised NPs using T. procumbens leaf extract was tested against Aedes aegypti species (dengue, chikungunya, zika and yellow fever transmit vector).Inspec keywords: photoluminescence, spectrophotometry, thermal analysis, chromatography, nanoparticles, antibacterial activity, field emission electron microscopy, microorganisms, wide band gap semiconductors, scanning electron microscopy, X‐ray diffraction, copper compounds, ultraviolet spectra, nanofabrication, X‐ray chemical analysis, crystallites, visible spectra, field emission scanning electron microscopy, nanobiotechnology, semiconductor materials, semiconductor growth, fluorescence, mass spectraOther keywords: energy dispersive spectroscopy, ultraviolet–visual spectrophotometry, fluorescence spectroscopy, chikungunya, green synthesis, mosquito larvicidal activity, zika, X‐ray diffraction analysis, field‐emission scanning electron microscopy, XRD, gas chromatography–mass spectrometry, copper oxide nanoparticles, dengue, tridax procumben leaf extract, nanomosquitocides, FTIR, monoclinic structure, crystallite size, photoluminescence spectra, near‐band‐edge emission band, phytochemical constituents, Aedes aegypti species, yellow fever transmit vector, CuO     

A proposed specimen for KIIC testing

Unlike mode I, mode II fracture toughness (K_IIC) testing is still some way from standardization. In the present study, a specimen is proposed for K_IIC testing. The specimen is an adaptation of Richard's (1981) specimen, with the exception that the ligament is extended. Based on numerical analysis, the suitability of the proposed specimen has been assessed by comparing it against the two commonly-used mode II specimens of Banks-Sills and Arcan (1986), and Richard (1981), respectively. In comparison, the proposed specimen has been found to be more compact, and to have a significantly lower intensity of normal stress ahead of the crack tip. As a result, it may be inferred that the proposed specimen would be more suitable for K_IIC testing. The modes I and II K-calibration formulae of the proposed specimen have also been deduced.     

Design of high-speed 10-Gb/s wired/FSO systems for local area communication networks for maximum reach

Photonic Network Communications - This paper presents the numerical simulation studies of upgraded system for single-mode fiber (SMF wired)/free space optics (FSO wireless) under high-speed...     

Lattice energy and mechanical stiffness of hydroxyapatite

The lattice energy of the stoichiometric hydroxyapatite is calculated using three methods: the thermochemical method called Born-Fajans-Haber cycle (BHFC), the semi-empirical electrostatic method based on the generalized Kapustinskii equation, and the Glasser-Jenkins unit cell volume method. The three values of the lattice energy of the hydroxyapatite derived by the three methods are within 4% difference to each other (BHFC: 34,191 KJ/mole, generalized Kapustinskii equation: 32,808.9 KJ/mole, unit cell volume: 32,997.4 KJ/mole). The Voigt and Reuss effective elastic moduli of 19 simple ionic crystals, including those of the hydroxyapaptite, are calculated and are found to be linearly dependent on their volumetric lattice energy density (LED).     

Functional Patterning of Biopolymer Thin Films Using Enzymes and Lithographic Methods

Two different lithographic techniques for the patterning of thin biopolymer films are developed. The first method is based on using a microstructured elastomeric mold for the structuring of thin films of regenerated cellulose. The thin films are manufactured by spin‐coating of trimethylsilyl cellulose (TMSC) and subsequent regeneration. The microchannels formed by the mold and the cellulose film are filled with a cellulase solution by capillary action. In the areas exposed to the enzyme solution, the cellulose film is digested, whereas the area in contact with the mold is protected from the enzymatic activity. Optical thickness measurements, atomic force microscopy and fluorescent staining confirm a successful patterning of cellulose on several substrates by this method. The second method is based on the structured regeneration of thin TMSC films. TMSC surfaces are protected with metal masks and exposed to vapors of hydrochloric acid. These treatments result in hydrophilic cellulose structures surrounded by hydrophobic TMSC with differing physicochemical properties. Treatments of the obtained structures with cellulases allow the selective removal of pure cellulose, whereas a TMSC pattern remains on the surface. These TMSC can be regenerated back to pure cellulose by treatments with vapors of hydrochloric acid. The developed methods allow the effective fabrication of micropatterned biopolymer thin films suitable for further functionalization and application in, e.g., bioanalytical devices. This is shown by the immobilization and detection of single‐stranded DNA on structured cellulose surfaces. Owing to the versatility of both patterning approaches the methods can be further extended to other combinations of substrates and enzymes.     

Synthesis and nonlinear optical properties of Lead Telluride nanorods

Lead Telluride (PbTe) nanorods have been uniformly grown on silicon substrates, using the thermal evaporation technique under high vacuum conditions. The structural and morphological studies are done using X-ray diffraction and scanning electron microscopy. Optical nonlinearity studies using the open aperture z-scan employing 5 ns and 100 fs laser pulses reveal a three-photon type absorption. For nanosecond excitation the nonlinear absorption coefficients (γ) are in the order of 10⁻²² m³ W⁻² and for femtosecond excitation it is in the order of 10⁻²⁹ m³ W⁻². The role of free carriers and excitons in causing the nonlinearity in both excitation time domains is discussed. Results indicate that PbTe nanorods are good optical limiters with potential device applications.     

Comparison of treatment potential of electrocoagulation of distillery effluent with and without activated Areca catechu nut carbon

Physico-chemical characteristics of distillery effluent samples have been determined. The water quality parameters (WQPs) measured are colour, pH, electrical conductivity, turbidity, total dissolved solids (TDS), chloride, total hardness (THA), calcium, iron, bio-chemical oxygen demand (BOD) and chemical oxygen demand (COD). Almost all the values of WQPs of the distillery effluents have been found to be very high and well above the permissible limit suggested by Bureau of Indian Standards (BIS). Electrocoagulation (EC) technique is employed to treat the distillery effluents. Removal efficiency of WQPs is compared by adopting EC technique with and without the addition of indigenously prepared activated areca nut [botanical name: Areca catechu; kotta pakku, in (vernacular)] carbon (AAC). About 99% of turbidity has been removed in both the cases. The experimental results also revealed that the WQPs like EC, TDS, etc. of the effluents could be reduced. Loss of weight of sacrificial electrode (anode) is also ascertained. EC with AAC is found to be more effective than EC without AAC.