AN EXPERIMENTAL INVESTIGATION IN AN ATMOSPHERE ENTRY SIMULATOR OF NYLON AS AN ABLATIVE MATERIAL FOR BALLISTIC MISSILES

Investigation in atmosphere entry simulator of nylon as ablative material for ballistic missile

Mathieu beams as versatile light moulds for 3D micro particle assemblies

We present tailoring of three dimensional light fields which act as light moulds for elaborate particle micro structures of variable shapes. Stereo microscopy is used for visualization of the 3D particle assemblies. The powerful method is demonstrated for the class of propagation invariant beams, where we introduce the use of Mathieu beams as light moulds with non-rotationally-symmetric structure. They offer multifarious field distributions and facilitate the creation of versatile particle structures. This general technique may find its application in micro fluidics, chemistry, biology, and medicine, to create highly efficient mixing tools, for hierarchical supramolecular organization or in 3D tissue engineering

Electrochemical Evaluation of LaNi_(5–x)Ge_x Metal Hydride Alloys

We report a detailed evaluation of Ge-substituted LaNi_5 for electrochemical application as a negative electrode in alkaline rechargeable cells. Alloys with small substitutions of Ge for Ni show operating pressures, chargeability, cyclic lifetime, and kinetics for hydrogen absorption and desorption all superior to those found in many other substituted LaNi_5 alloys. These improved properties were achieved with a minimal reduction in hydrogen storage capacity

Hydrogen desorption and adsorption measurements on graphite nanofibers

Graphite nanofibers were synthesized and their hydrogen desorption and adsorption properties are reported for 77 and 300 K. Catalysts were made by several different methods including chemical routes, mechanical alloying, and gas condensation. The nanofibers were grown by passing ethylene and H2 gases over the catalysts at 600 °C. Hydrogen desorption and adsorption were measured using a volumetric analysis Sieverts' apparatus, and the graphite nanofibers were characterized by transmission electron microscopy and Brunauer–Emmett–Teller surface area analysis. The absolute level of hydrogen desorption measured from these materials was typically less than the 0.01 H/C atom, comparable to other forms of carbon

Electrochemical Studies on LaNi5–xSnx Metal Hydride Alloys

Electrochemical studies were performed on LaNi5–xSnx with 0 <= x <= 0.5. We measured the effect of the Sn substituent on the kinetics of charge-transfer and diffusion during hydrogen absorption and desorption, and the cyclic lifetimes of LaNi5–-xSnx electrodes in 250 mAh laboratory test cells. We report beneficial effects of making small substitutions of Sn for Ni in LaNi5 on the performance of the metal hydride alloy anode in terms of cyclic lifetime, capacity, and kinetics. The optimal concentration of Sn in LaNi5–xSnx alloys for negative electrodes in alkaline rechargeable secondary cells was found to lie in the range 0.25 <= x <= 0.3

Electrochemical Properties of LaNi5–xGex Alloys in Ni-MH Batteries

Electrochemical studies were performed on LaNi5–xGex metal hydride alloys with 0 <= x <= 0.5. We carried out single-electrode studies to understand the effects of the Ge substituent on the hydrogen absorption characteristics, the electrochemical capacity, and the electrochemical kinetics of hydrogen absorption and desorption. The electrochemical characteristics of the Ge-substituted alloys are compared to those of the Sn-substituted alloys reported earlier. LaNi5–xGex alloys show compositional trends similar to LaNi5–xSnx alloys, but unlike the Sn-substituted alloys, Ge-substituted alloys continue to exhibit facile kinetics for hydrogen absorption/desorption at high solute concentrations. Cycle lives of LaNi5–xGex electrodes were measured in 300 mAh laboratory test cells and were found to be superior to the Sn-substituted LaNi5 and comparable to a Mm(Ni,Co,Mn,Al)5 alloy. The optimum Ge content for LaNi5–xGex metal hydride alloys in alkaline rechargeable cells is in the range 0.4 <= x <= 0.5

Growth studies on Neurospora crassa

Growth studie