On Structural,Optical, and Electrical Properties of Chromium Oxide Cr2O3 Thin Film for Applications

Protection of Metals and Physical Chemistry of Surfaces - Chromium oxide thin films were grown on Al2O3 substrates by ablating a pure Cr2O3 target using a KrF excimer laser. The energy density on...     

Highly luminescent film functionalized with CdTe quantum dots by layer‐by‐layer assembly

Robust and facile strategies are required to fabricate film with high luminescence for application in the fields of biomaterials. In this study, the luminescent electrospinning cellulose fibrous mats were decorated with CdTe quantum dots (QDs) and poly(diallyl dimethyl ammonium chloride) (PDDA) using layer by layer (LBL). The characterizations of the LBL films coated mats were executed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, fluorescent spectroscopy, X‐ray diffraction, thermal gravimetric analysis, and differential scanning calorimetry. The luminescent intensities were linearly increased with adding the amount of deposited bilayers. The green fabricated (QDs/PDDA)_n coated mat through physical interactions is a promising luminescent material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41893.     

Aspects of varying crosslinker and catalyst concentrations on tear strength of silicone polymer networks: Comparison of tear strengths using samples of different geometries

Crosslinker and catalyst concentrations have been varied to prepare different hydroxyfunctional poly(dimethylsiloxane) (HOPDMS) polymer network compositions. The tear strengths of these silicone polymer networks have been measured using different geometries, as trouser, crescent, and Graves (angled) specimens. It has been observed that the results of tear strength of Graves and crescent‐shaped specimens do not show a constant ratio with the concentration of crosslinker used for curing of HOPDMS networks. Instead, it has been observed and reported for the first time that the tear strengths of Graves and crescent‐shaped samples show a crossover at about 1.2% crosslinker. The observation of this crossover pattern for different compositions of silicone networks show that it is difficult to compare the results of the tear test of the same polymer performed on samples of different geometries with one another. The crossover pattern of the tear energy results for the test specimens of two different geometries has been explained in the light of essential work facture theory based on the geometry of the testing sample, crosslinking, and testing that alters the distribution of force over the width of the specimen. It was shown that the change in composition of the HOPDMS networks changes the order of ranking of Graves and crescent tear tests. With varying catalyst concentration in the silicone network composition, the tear property differences between the Graves and crescent‐shaped specimens are not significant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43115.     

Ultra-high strength Mg-9Gd-4Y-0.5Zr alloy with bi-modal structure processed by traditional extrusion

It is usual to observe that multi-scale structures can lead to combined strength and ductility both in aluminum alloys and steels, but related research has been seldom reported yet in magnesium alloys. In this study, applying traditional one step extrusion, we have successfully obtained a bimodal (Mg-9Gd-4Y-0.5Zr) alloy capable of ultra-high strength. The characterized sample reveal a bi-modal microstructure with two constitutions, i.e. stretched coarse-grain region with strong basal fiber texture and recrystallization fine-grain region. The bi-modal structured sample exhibit excellent mechanical properties with an ultimate strength 508 MPa and elongation 8% via 400 °C extrusion and subsequently 200 °C-60 h peak aging process. Ultra-high strength can be attributed to its strong extrusion texture in stretched coarse grains and dispersed nano-scale precipitates. This unique bimodal structure could be produced easily by one step extrusion, which is quite reliable and low costs in industrial applications of magnesium alloys with ultra-high strength as well as ideal ductility.     

Accelerated Design of Eutectic High Entropy Alloys by ICME Approach

Eutectic high entropy alloy with seven components is designed based on the integrated computational materials engineering (ICME) framework. The framework includes thermodynamic prediction using calculation of phase diagrams (CALPHAD), microstructure simulation using phase-field method, and experimental validation. The designed alloy shows the eutectic structure consisting of FCC and laves phase in the composition range from 8.25 to 10 at. pct Ta. The simulation and experimental results are co-related and a framework is proposed that can be used for high entropy alloy design subjected to various manufacturing processes.

     

Synthesis of nanostructured copper hexacyanidoferrate and its application in voltammeteric detection of salbutamol

Nanostructured copper hexacyanidoferrate has been synthesized and characterized using elemental analysis, atomic absorption spectroscopy, thermal and infrared spectral studies. The transmission electron microscopic studies of the synthesized material showed that it consisted of irregular oval and rod shaped particles with a size range 70–100 nm. Nanostructured copper hexacyanidoferrate modified glassy carbon electrode was characterized by cyclic voltammetery and nanostructured copper hexacyanidoferrate–carbon nanotube composite material modified glassy carbon electrode has been used for electrocatalytic oxidation of salbutamol. The electrode modified with composite material was found to reduce the peak potential of oxidation of salbutamol by nearly 90 mV.     

Preparation of CaCO3‐based biomineralized polyvinylpyrrolidone–carboxymethylcellulose hydrogels and their viscoelastic behavior

In the blend of natural and synthetic polymer‐based biomaterial of polyvinylpyrrolidone (PVP) and carboxymethylcellulose (CMC), fabrication of CaCO₃ was successfully accomplished using simple liquid diffusion technique. The present study emphasizes the biomimetic mineralization in PVP–CMC hydrogel, and furthermore, several properties of this regenerated and functionalized hydrogel membranes were investigated. The physical properties were studied and confirmed the presence of CaCO₃ mineral in hydrogel by Fourier transform infrared spectroscopy and Scanning electron microscopy. Moreover, the absorptivity of water and mineral by PVP–CMC hydrogel was studied to determine its absorption capacity. Further, the viscoelastic properties (storage modulus, loss modulus, and complex viscosity) of mineralized and swelled samples (time: 5–150 min) were measured against angular frequency. It is interesting to know the increase of elastic nature of mineralized hydrogel filled with CaCO₃ maintaining the correlation between elastic property and viscous one of pure hydrogel. All these properties of biomineralized hydrogel suggest its application in biomedical field, like bone treatment, bone tissue regeneration, dental plaque and tissue replacement, etc. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40237.