Studies on synthesis of calcium ferrite-based bio glass ceramics

The possibility of synthesizing a Ca-ferrite based biocompatible glass ceramic has been explored in the following two glass compositions: (i) 28Na₂O-8CaO-3P₂O₅-llFe₂O₃-50SiO₂, and (ii) 25Na₂O-8CaO-3P₂O₅-20Fe₂O₃-41SiO₂-3B₂O₃ (in weight ratio). The effect of simulated body fluid on the different glasses and glass ceramics was also investigated. While there is no direct evidence for apatite formation, the weight losses recorded and formation of a Si-rich layer at the surface appears to be an indication of onset of apatite formation. The rate of apatite formation is presumably retarded due to the presence of Al³⁺ (picked up from AL₂O₃ crucible). Ferromagnetic resonance experiments at 9.03 GHz demonstrate that these glass ceramics can possibly be used for microwave hyperthermia.     

In0.2Ga0.8As/GaAs quantum well laser with C doped cladding and ohmic contact layers

Carbon doping in Al_xGa_1−xAs was achieved using different approaches. The moderate growth temperature of 650°C was employed to grow C bulk-doped Al_xGa_1−xAs with a high Al mole fraction. The hole-density was altered using different V/III ratios. The trimethylaluminum (TMAl) was used as an effective C δ-doping precursor for growth of C δ-doped pipi doping superlattices in Al_xGa_1−xAs. the average hole-density of C δ-doped pipi superlattices was greater than 2−3 × 10¹⁹ cm⁻³. Zn-free GRINSCH In_0.2Ga_0.8As/GaAs laser structures were then grown using the C bulk-doped Al_xGa_1−xAs and C δ-doped pipi superlattice as a cladding and ohmic contact layer, respectively. The ridge waveguide laser diodes were fabricated and characterized to verify flexibility of these two doping approaches for device structures.     

It's all about speed

The authors discuss techniques for increasing the speed of interconnects by using steerable lasers for free-space optical communications.     

Hydrogen incorporation, diffusivity and evolution in bulk ZnO

Hydrogen is readily incorporated into bulk, single-crystal ZnO during exposure to plasmas at moderate (100–300°C) temperatures. Incorporation depths of >25 μm were obtained in 0.5 h at 300°C, producing a diffusivity of 8 × 10⁻¹⁰ cm²/V s at this temperature. The activation energy for diffusion is 0.17 ± 0.12 eV, indicating an interstitial mechanism. Subsequent annealing at 500–600 °C is sufficient to evolve all of the hydrogen out of the ZnO, at least to the sensitivity of Secondary Ion Mass Spectrometry (<5 × 10¹⁵ cm⁻³). The thermal stability of hydrogen retention is slightly greater when the hydrogen is incorporated by direct implantation relative to plasma exposure, due to trapping at residual damage.     

Properties and sorption studies of polyethylene oxide–starch blended films

A series of polyethylene oxide (PEO) and starch blends were prepared by extrusion and their films prepared by compression molding. The mechanical, barrier, optical, thermal properties and surface morphology characteristics of PEO–starch blended films were studied. The tensile strength of the blended films decreased whereas the haze values increased with an enhanced starch concentration in PEO–starch blends. The inter-molecular interaction between PEO–starch blends were investigated with FTIR. The thermal properties were also analyzed by differential scanning calorimetric (DSC) and thermo-gravimetric analysis (TGA) techniques. Moisture-sorption characteristics of PEO–starch blended films were carried out at 27 °C for water activity (a_w) ranged from 0.1 to 0.9. The sorption data at different a_w were used to fit different sorption isotherm models as proposed in the literatures. The model constants were determined by linear fitting of the sorption equations. The high coefficient of determination R² (ranged from 0.7 to 1) confirms the applicability of the equations employed. The study on the application of such water activity data of PEO/starch blended films on different model equations will be helpful in prediction of durability and functional behavior of moisture sensitive biopolymeric films.     

Evolution of Wurtzite Structured GaAs Shells Around InAs Nanowire Cores

GaAs was radially deposited on InAs nanowires by metal–organic chemical vapor deposition and resultant nanowire heterostructures were characterized by detailed electron microscopy investigations. The GaAs shells have been grown in wurtzite structure, epitaxially on the wurtzite structured InAs nanowire cores. The fundamental reason of structural evolution in terms of material nucleation and interfacial structure is given.