Defect studies on as-synthesized and purified carbon nanostructures produced by arc-discharge in solution process

Carbon nanostructures are synthesized using a novel arc-discharge in solution process. A multitude of defects on nanotubes and nanostructures is found. Evidence of these defects in as-synthesized carbon nanostructures is explored using high-resolution transmission electron microscopy (HRTEM). Tri-, tetra-, penta-, hexa-, heptagonal, toroidal, oval, and spherical nanoshells are found in HRTEM investigation along with carbon nanotubes, carbon nanohorns, carbon rods, nanoporous carbon, dislodged graphene sheets, and amorphous carbon. Purifications are carried out through two oxidation methods to eliminate the amorphous carbon. Several different defects caused by oxidations are also found in purified samples.     

Spiral growth of one dimensional titania nanostructures using anodic oxidation

One dimensional spiral titania nanostructures were obtained by anodization of pure titanium from fluoride containing solutions of phosphoric acid. The formation of nanotubes was found to be dependant on current density. Field Emission Scanning Electron Microscopy (FESEM) shows the diameter of tubes around 70-100 nm which is consistent with the High Resolution Transmission Electron Micrographs (HRTEM) and Atomic Force Microscopy (AFM) images. HRTEM showed the one dimensional growth as spiral in nature which was also supported by AFM images. This anisotropic growth is compared with the possible growth mechanisms.     

Development of a motion simulator for testing a mobile surveillance robot

A 6-axis motion simulator has been developed, in order to regenerate UGV (unmanned ground vehicle) motion and to test the stabilization system of the mobile surveillance robot that is mounted on the UGV. For developing the 6-axis motion simulator, a simulation-based design procedure was introduced. The 3D geometric model of the motion simulator was created by using 3D CAD modeler ProE. The multibody dynamics model of the motion simulator has also been created by using the general purpose dynamic analysis program ADAMS to validate the design of the motion simulator. Dynamics and control co-simulation model for the motion simulator has been also established for control performance analyses. Actual hardware of the motion simulator has been fabricated based on the proposed simulation based design. Hardware test of the motion simulator has been tried to validate the design. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Oskar Wallrapp was awarded a Ph.D. degree in Mechanical Engineering at the Technical University of Berlin, Germany in 1989. Dr. Wallrapp is currently a Professor in the Department of Precision and Micro Engineering, Muenchen University of Applied Science, Munich, Germany. His research interests are mechanism analysis and design, robotics, and bio-mechanics. Sung-Soo Kim received a Ph.D. degree in Mechanical Engineering from the University of Iowa in 1988. Dr. Kim is currently a Professor in the Department of Mechatronics Engineering at Chungnam National University in Daejeon, Korea. His research interests are real-time multibody formulation and its application to the automotive systems and military robot systems.     

Microstructural modification and ageing behaviour of the Al–17Si–5Cu alloy using a novel approach

A novel short duration heat treatment schedule is proposed in the present investigation for the Al-17?wt-% Si-5?wt-% Cu alloy (AR alloy). The existing heat treatment uses long duration (4–24?h) holding at solutionising temperature prior to ageing treatment. In the present investigation, the AR alloy is subjected to isothermal holding at 590°C for 15?min followed by warm water quenching prior to the normal ageing schedule. Detailed microstructural investigations involving size and shape of primary as well as eutectic Si particles, porosity measurements along with hardness and tensile property characterisation are carried out to find the effect of isothermal heat treatment. The study reveals considerable improvement in microstructure and mechanical properties after this isothermal heat treatment.     

I: Dispersibility of robust alumina particles in non-aqueous solution

This article presents the preparation of well dispersed alumina slurries containing relatively large alumina particles that can withstand accelerated weather conditions. Besides using conventional dispersants such as phosphate esters and menhaden fish oil, dispersants widely used in the surface coatings industries such as Disperbyk 110 and Triton X 100 have also been employed. However, sedimentation tests, sediment density, viscosity and gloss measurements indicate the failure of the anionic dispersants as well as menhaden fish oil to disperse the alumina particles in non-aqueous medium. Instead the binder polyvinyl butyral itself acts as the best dispersant. The well dispersed alumina slurry is stabilized in the presence of a commercially available rheology modifier, Bentone SD2 for a period of 144 h at 60 °C. The rheological behavior of the aged sample was studied under various conditions. Although a rise in viscosity of the suspension was observed when the slurry was exposed to accelerated weather conditions, a lower shear thinning index and higher gloss values indicate a better dispersion state with aging.     

3D Coordination Network of Ag(I) Ions with μ 3 -Bridging Melamine Ligands

Abstract  

A new 3D silver complex [Ag(mela)(H₂O)(NO₃)]_n (1) (mela = melamine or 2,4,6-triaminotriazine) is synthesized and characterized by single crystal X-ray diffraction, IR, and elemental analysis. The structural characterization shows that the compound crystallizes in space group C c, a = 8.181(2), b = 10.269(3) c = 11.347(3) ?, β = 105.88(2)°, Z = 4. Out of several structurally characterized transition metal compounds comprising melamine, the titled complex represents a rare example of μ ₃ -melamine coordination mode realized through the heterocycle nitrogen donors. The fluorescent property of complex 1 was investigated and the mechanism was validated by means of a density functional theory (DFT) calculation.     

Overview of Steel Bridges Containing High Strength Steel

The use of high strength steel has the potential to reduce the amount of steel used in bridges and thereby, facilitate a more sustainable construction. A survey of existing bridges built using high strength steel is presented in this paper with emphasis on the Swedish bridge stock. The survey aimed at identifying the steel grades that were used and where in the cross-section they have been used. A case study on the influence of fatigue shows that today’s regulations make it more difficult to use high strength steel in comparison to previous regulations.

     

The Effect of Rock-crude Oil-fluid Interactions on Wettability Alteration of Oil-wet Sandstone in the Presence of Surfactants

The aim of the present work was to study the rock-fluid interaction in presence of surfactants and thereby their effects on wettability alteration of oil-wet sandstone for its essentiality in enhanced oil recovery. Characterization of sandstone sample and its interaction with crude oil, brine and surfactants were investigated by Fourier Transform Infrared spectroscopy. Scanning electron microscope and X-ray diffraction studies were performed to characterize the sandstone sample. Critical micelle concentrations of sodium dodecyl sulfate, cetyltrimethylammonium bromide, Tergitol 15-S-7, Tergitol 15-S-9, and Tergitol 15-S-12 were determined by interfacial tension measurement method. Wettability alteration of sandstone was studied by contact angle method.     

Enantioselective Synthesis of α‐Amino‐γ‐sulfonyl Phosphonates with a Tetrasubstituted Chiral α‐Carbon via Quinine‐Squaramide‐Catalyzed Michael Addition of Nitrophosphonates to Vinyl Sulfones

α‐Nitro‐γ‐sulfonyl phosphonates with a key tetrasubstituted chiral α‐carbon center have been synthesized for the first time in high yield and enantioselectivity through a quinine‐squaramide‐catalyzed conjugate addition of α‐nitro phosphonates to aryl vinyl sulfones. Representative examples presented here for the transformation of nitrosulfonyl phosphonates to aminosulfonyl phosphonates, alkylation at the α‐position of the sulfonyl group followed by desulfonation and scale‐up of the conjugate addition highlight the practical applications of the methodology.