Opening the ‘Non-Manufacturing’ envelope: The next big enterprise for international business research

Abstract and Key Results

Oxide-encapsulated vertical germanium nanowire structures and their DC transport properties

We demonstrate the p-type doping of Ge nanowires (NWs) and p-n junction arrays in a scalable vertically aligned structure with all processing performed below 400?°C. These structures are advantageous for the large scale production of parallel arrays of devices for nanoelectronics and sensing applications. Efficient methods for the oxide encapsulation, chemical mechanical polishing and cleaning of vertical Ge NWs embedded in silicon dioxide are reported. Approaches for avoiding the selective oxidation and dissolution of Ge NWs in aqueous solutions during chemical mechanical polishing and cleaning of oxide-encapsulated Ge NWs are emphasized. NWs were doped through the epitaxial deposition of a B-doped shell and transport measurements indicate doping concentrations on the order of 10(19)?cm(-3).     

Exciton dissociation and stark effect in the carbon nanotube photocurrent spectrum

The field-dependent photocurrent spectrum of individual carbon nanotubes is measured using a displacement photocurrent technique. A series of peaks is observed in the photocurrent corresponding to both excitonic and free carrier transitions. The photocurrent peak corresponding to the ground state exciton increases by a factor of 200 beyond a critical electric field, and shows both red and blue shifts depending on the field regime. This provides evidence for field-induced mixing between excitonic and free carrier states.     

Novel poly(methyl methacrylate)‐block‐polyurethane‐block‐poly(methyl methacrylate) tri‐block copolymers through atom transfer radical polymerization

Poly(methyl methacrylate)‐block‐polyurethane‐block‐poly(methyl methacrylate) tri‐block copolymers have been synthesized successfully through atom transfer radical polymerization of methyl methacrylate using telechelic bromo‐terminated polyurethane/CuBr/N,N,N,N″,N″‐pentamethyldiethylenetriamine initiating system. As the time increases, the number‐average molecular weight increases linearly from 6400 to 37,000. This shows that the poly methyl methacrylate blocks were attached to polyurethane block. As the polymerization time increases, both conversion and molecular weight increased and the molecular weight increases linearly with increasing conversion. These results indicate that the formation of the tri‐block copolymers was through atom transfer radical polymerization mechanism. Proton nuclear magnetic resonance spectral results of the triblock copolymers show that the molar ratio between polyurethane and poly (methyl methacrylate) blocks is in the range of 1 : 16.3 to 1 : 449.4. Differential scanning calorimetry results show T_g of the soft segment at ?35°C and T_g of the hard segment at 75°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of niobium and grain boundary density on the fire resistance of Fe–C–Mn steel

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Effect of Rectangular Winglet Pair in Common Flow Down Configuration on Heat Transfer from an Isothermally Heated Plate

ABSTRACT

Present three-dimensional numerical study aims to investigate the effect of mounting rectangular winglet pair (RWP) on heat transfer enhancement in flow over a flat plate. Computations for incompressible flow of air have been carried out using commercial software ANSYS Fluent. Flow of air has been considered over the surface of an isothermally heated horizontal plate in presence of RWP in the range of Reynolds number from 400 to 2000. Common flow down configuration of RWP has been considered to study the effect of various geometric parameters, such as length of RWP, spacing between leading edges of the winglets and angle of attack of RWP, on flow characteristics and enhancement in heat transfer. Flow and temperature field characteristics have been presented using streamlines and temperature contours near the plate surface and streamlines in cross-stream planes. Enhancement in heat transfer in presence of RWP has been quantified using cross-stream variation of local Nusselt number, streamwise variation of span-averaged Nusselt number and surface-averaged overall Nusselt number.     

A new multi-resolution hybrid wavelet for analysis and image compression

Most of the current image- and video-related applications require higher resolution of images and higher data rates during transmission, better compression techniques are constantly being sought after. This paper proposes a new and unique hybrid wavelet technique which has been used for image analysis and compression. The proposed hybrid wavelet combines the properties of existing orthogonal transforms in the most desirable way and also provides for multi-resolution analysis. These wavelets have unique properties that they can be generated for various sizes and types by using different component transforms and varying the number of components at each level of resolution. These hybrid wavelets have been applied to various standard images like Lena (512 × 512), Cameraman (256 × 256) and the values of peak signal to noise ratio (PSNR) obtained are compared with those obtained using some standard existing compression techniques. Considerable improvement in the values of PSNR, as much as 5.95 dB higher than the standard methods, has been observed, which shows that hybrid wavelet gives better compression. Images of various sizes like Scenery (200 × 200), Fruit (375 × 375) and Barbara (112 × 224) have also been compressed using these wavelets to demonstrate their use for different sizes and shapes.     

Electrospun Differential Wetting Membranes for Efficient Oil–Water Separation

Separation of low viscous oil from water has attracted immense attention in recent times due to the ever‐increasing amount of oily industrial wastewater discharge and frequent oil spill accidents. Hence, there is a persistent demand for the fabrication of robust oil–water separation membranes. Herein, robust oil–water separation membranes are successfully fabricated by direct electrospinning of poly(vinylidene fluoride‐co‐hexafluoropropylene) and fluorinated polyhedral oligomeric silsesquioxane composite mixture. These hybrid membranes exhibit differential wetting (highly hydrophobic/superoleophilic) behavior for water and oil. The contact angle made by water and low viscous oil (hexane) with the membrane are measured to be 145 and 0° respectively. The nanofiber membranes efficiently separate low viscous oil from water in a single‐step with separation efficiency of nearly 100%. Furthermore, the results demonstrate that the membranes are robust and durable exhibiting differential wettability even after several oil–water separation cycles. The results reveal the potential of their use for real‐time industrial wastewater treatment applications.

     

A computational model for assessing impact of interfacial morphology on polymer electrolyte fuel cell performance

A two-dimensional, non-isothermal, anisotropic numerical model is developed to investigate the impact of the interfacial morphology between the micro-porous layer (MPL) and the catalyst layer (CL) on the polymer electrolyte fuel cell (PEFC) performance. The novel feature of the model is the inclusion of directly measured surface morphological information of the MPL and the CL. The interfacial morphology of the MPL and the CL was experimentally characterized and integrated into the computational framework, as a discrete interfacial layer. To estimate the impact of MPL|CL interfacial surface morphology on local ohmic, thermal and mass transport losses, two different model schemes, one with the interface layer and one with the traditionally used perfect contact are compared. The results show a ∼54 mV decrease in the performance of the cell due to the addition of interface layer at 1 A cm⁻². Local voids present at the MPL|CL interface are found to increase ohmic losses by ∼37 mV. In-plane conductivity adjacent to the interface layer is determined to be the key controlling parameter which governs this additional interfacial ohmic loss. When the interfacial voids are simulated to be filled with liquid water, the overpotential on the cathode side is observed to increase by ∼25 mV. Local temperature variation of up to 1 °C is also observed at the region of contact between the MPL and the CL, but has little impact on predicted voltage.     

Phosphorene: Current status,challenges and opportunities

The field of 2-dimensional (2D) materials has witnessed a sharp growth since its inception and can majorly be attributed to the substantial technical and scientific developments, leading to significant improvements in their syntheses, characterization and applications. In the list of 2D materials, the relatively newer addition is phosphorene, which ideally consists of a single layer of black phosphorous. Keeping in mind the past, and ongoing research activities, this short account offers a brief overview of the present status and the associated challenges in the field of phosphorene-related research, with special emphasis on their syntheses, properties, applications and future opportunities.