Synthesis of spherical Al2O3 and AlN powder from C@Al2O3 composite powder

A novel approach has been taken to produce (1) spherical Al₂O₃ particles by decarbonisation and (2) spherical AlN particles by nitridation and subsequent decarbonisation of C@Al₂O₃ composite particles. C@Al₂O₃ composite particles have been prepared by heterogeneous nucleation and crystallisation of Al(NO₃)₃ on surfactant encapsulated carbon nano particles followed by evaporative decomposition of the nitrate. Overpressure (0.4 MPa) of nitrogen and a temperature range (1723–1873 K) have been used for nitridation. Whiskers as well as spherical particles of AlN have been observed in the final product. The final product has been characterised by X-Ray Diffraction, Scanning Electron Microscope and Carbon–Hydrogen–Nitrogen content analysis by Elemental Analyser and the mechanism of the nitridation reaction has been analysed. The average size of the spherical AlN particles consisting of crystallites in nano-dimensions (30–50 nm) could be varied from 100 nm to 8 μm by changing the composition of the sol.     

Separation of acid–water mixtures by pervaporation using nanoparticle filled mixed matrix copolymer membranes

BACKGROUND: Low energy and less expensive membrane based separation of acetic acid‐water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5:1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na‐MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 °C. Similarly for a dilute acid–water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic‐water mixtures. Copyright © 2012 Society of Chemical Industry     

First-principles studies of the superconductivity and vibrational properties of transition-metal nitrides TMN (TM = Ti,V, and Cr)

The present paper reports the structural, electronic, phonon and thermodynamical properties of some transition-metal nitrides (TMN: TiN, VN and CrN) by means of first-principles calculations. The computed equilibrium lattice constant and bulk modulus agree well with the available experimental and theoretical data. The electronic band structure and density of states calculations show metallic nature. The phonon frequencies are positive throughout the Brillouin zone for these compounds in rocksalt structure indicating dynamical stability. The calculated electron–phonon coupling constant λ and superconducting transition temperature agree reasonably well with the available experimental data. These compounds behave as a conventional phonon-mediated superconductor. Within the GGA and quasi-harmonic approximation, thermodynamical properties are also investigated.     

Nanointerfacial strength between non-collagenous protein and collagen fibrils in antler bone

Antler bone displays considerable toughness through the use of a complex nanofibrous structure of mineralized collagen fibrils (MCFs) bound together by non-collagenous proteins (NCPs). While the NCP regions represent a small volume fraction relative to the MCFs, significant surface area is evolved upon failure of the nanointerfaces formed at NCP–collagen fibril boundaries. The mechanical properties of nanointerfaces between the MCFs are investigated directly in this work using an in situ atomic force microscopy technique to pull out individual fibrils from the NCP. Results show that the NCP–fibril interfaces in antler bone are weak, which highlights the propensity for interface failure at the nanoscale in antler bone and extensive fibril pullout observed at antler fracture surfaces. The adhesion between fibrils and NCP is additionally suggested as being rate dependent, with increasing interfacial strength and fracture energy observed when pullout velocity decreases.     

Electrical Conduction in Nano-Structured La0.9Sr0.1Al0.85Co0.05Mg0.1O3 Perovskite Oxide

Nanocrystalline La_0.9Sr_0.1Al_0.85Co_0.05Mg_0.1O₃ oxide powder was synthesized by a citrate–nitrate auto-ignition process and characterized by thermal analysis, X-ray diffraction, and impedance spectroscopy measurements. Nanocrystalline (50–100 nm) powder with perovskite structure could be produced at 900°C by this process. The powder could be sintered to a density more than 96% of the theoretical density at 1550°C. Impedance measurements on the sintered samples unequivocally established the potential of this process in developing nanostructured lanthanum aluminate-based oxides. The sintered La_0.9Sr_0.1Al_0.85Co_0.05Mg_0.1O₃ sample exhibited a conductivity of 2.40 × 10⁻² S/cm in air at 1000°C compared with 4.9 × 10⁻³ S/cm exhibited by La_0.9Sr_0.1Al_0.85Mg_0.15O₃.     

Effect of Active Raw Material Variability on Tablet Production: Physicochemical, Physiocomechanical and Pilot Plant Studies

Batch-to-batch variation in an active raw material was evaluated following a production process change by the raw material supplier. Physicochemical and physicomechanical tests were applied and indicated that polymorphism or solvate formation was not occurring but changes in crystal properties in terms of size and degree of aggregation were involved. Other more subtle differences in crystal properties were also possible

The deleterious effect of the raw material process change on tablet production was noted and a method of overcoming the problem identified

The necessity for comprehensive? reformulation studies including physicomechanical screening is underlined. Such studies are also necessary if changes in raw material production methods occur to avoid process problems related to the marked hatch-to-batch variation that can occur in these instances     

Synthesis of SiC ceramics from processed cellulosic bio-precursor

Synthesis of SiC ceramic from processed cellulosic bio-precursor was investigated. Bamboo (Bambusa tulda Roxb.) plants abundantly available in the Jorhat district of Assam, India, were selected for extraction of fibers following Kraft pulping method and bleached bamboo pulp fibers were suitably cast in the form of rectangular boards. Coir fibers available in the Alleppy district of Kerala, India, were initially digested with dilute alkali, mixed with cellulose acetate solution, air dried and then hot-pressed at 140 ± 5 °C under 2.0–2.5 MPa pressure to make rectangular boards. Well-characterized processed bio-precursors were pyrolysed at ～800 °C under flowing N₂ atmosphere to prepare the bio-carbonaceous preforms (carbon templates) which showed nearly uniform shrinkages in all directions. Coir fiber composite board carbon showed lower pyrolytic weight loss (～66%), higher density (0.49 g cm^?3), lower porosity (～58%) and narrower pore diameter (10 μm) compared to the cast bamboo pulp fiber board carbon. The carbon samples showed perfect retention of fibrous morphological features of hierarchically grown bio-structures. Ceramization of carbon templates could be done by reactive melt silicon infiltration into porous channels at ～1600 °C under vacuum. The final ceramics were adequately dense (%theoretical density > 99%), showed negligible linear dimensional changes (indicating net-dimension formation capability), presence of crystalline Si and SiC phases and duplex microstructure with complete preservation of fibrous architecture of plant bio-structure. The Si/SiC ceramic composite synthesized from coir fiber board gave room temperature 3-point flexural strength and Young's modulus values of 121 MPa and 276 GPa, respectively. Both the ceramic composites showed adequate oxidation resistance during heating at 1300 °C for 7 h in air.     

Visual representation of construction management data

Construction projects are associated with voluminous and often unstructured data sets, generated in support of construction management functions. Project managers face the challenge of making meaningful deductions from this data. A central contribution of this paper is that visual analytics can provide a means of analyzing data from various dimensions of a project to extract information in aid of decision making and helping to explain reasons for performance to date. Questions posed relate to the role of visual analytics in the execution and post-construction phases of a project, data representations and transformations of specific interest, and the kinds of visual representations and interactions that provide useful insights to management personnel, help explain performance, or assist with communication. Principles of designing effective visual analytics solutions for various construction management functions and applicable to the associated analytic reasoning tasks, data representations and transformations, and visual representations including relevant interaction features are described. Emphasis is placed on the choice of visual representations along with discussion of approaches for validating the usefulness of the visual analytics solutions proposed. The notion of context dimensions and performance dimensions for representing construction projects is introduced as part of the formulation of visual representation designs. To demonstrate the application of the concepts presented, data sets from two different projects were used to produce visual representations helpful for analytical reasoning about change order management data. A detailed assessment is given of several of the images presented in terms of strengths and weaknesses, and interaction features desired. The findings of the paper in terms of principles, concepts and lessons learned should prove helpful to those wishing to apply visual analytics to a broad range of construction management functions.     

Switching and memory devices based on a polythiophene derivative for data-storage applications

In this article, we report electrical characteristics of devices based on oriented and unoriented films of a polymer, namely poly[3-(6-methoxyhexyl)thiophene]. The current–voltage characteristics of sandwiched devices, based on unoriented polymer, showed hysteresis behavior, while oriented versions exhibited switching characteristics, i.e. presence of two conducting states depending on sweep direction of voltage scans. The ratio between the device current of two conducting states has been as high as 10⁵. This is comparable, if not better, than the results reported so far with complicated device architecture or doped polymeric materials. We have also demonstrated that the switching devices have an associated memory effect for data-storage applications.     

Electrolysis of black liquor for hydrogen production: Some initial findings

Electrolysis of black liquor, an effluent from paper industry, was carried out and compared with alkaline water electrolysis. Energy efficiency in terms of HHV of hydrogen was found in the range of 84–97% whereas under similar conditions alkaline water electrolysis could not give more than 66% efficiency. Hydrogen evolution in black liquor electrolysis was possible even at an inter electrode potential of 1.17 V but in alkaline water electrolysis there was no hydrogen production below an inter electrode potential of 1.31 V. In addition to this, alkali lignin, amounting to 28–46 mg/mg of hydrogen produced, was separated at anode during black liquor electrolysis, which, on account of its good calorific value, has the potential of significantly improving the overall energy efficiency of the process.