Ni/Pillared Clays as Catalysts for the Selective Catalytic Reduction of Nitrogen Oxides by Propene

Different and alternative methods for the preparation of Ni/pillared clays based on impregnation and encapsulation procedures are reported. Several nickel precursors and metal loadings are considered in order to evaluate their influence on the structural, textural and catalytic properties of the resulting solids. The behaviour of the optimum solids as catalysts has been proved in the selective catalytic reduction of nitrogen oxides with propene, and the relevance of the oxidant nature was checked by changing the composition of the oxidant mixture. Of all the factors studied, the nature of the nickel precursors appears as the most important one, owing to the formation of different active nickel species during the synthesis procedure.     

Multi-site phase transfer catalyst assisted radical polymerisation of glycidyl methacrylate using potassium peroxydisulphate as initiator – a kinetic study

In this work, the kinetics and mechanism of free-radical polymerisation of glycidyl methacrylate (GMA) using potassium peroxydisulphate (PDS) as water soluble initiator in the presence of synthesized 1, 4-Bis (tributyl methyl ammonium) benzene dichloride (TBMABDC) as multi-site phase transfer catalyst (MPTC) was studied. The polymerisation reactions were carried out under inert and unstirred conditions at constant temperature of 60 ± 1°C in cyclohexane/water biphase media. The role of concentrations of monomer, initiator, catalyst and volume fraction of aqueous phase, solvent polarity and temperature on the rate of polymerisation (Rp) was ascertained. The order with respect to monomer and initiator was found to be unity. The order with respect to catalyst was found to be 0.51. The rate of polymerisation is independent of ionic strength and pH of the medium. However, an increase in the polarity of solvent has slightly increased the Rp value. Based on the results obtained, a suitable kinetic scheme has been proposed to account for the experimental observations and its significance discussed.     

PURIFICATION AND PROPERTIES OF TRANSGLUTAMINASE FROM STREPTOVERTICILLIUM MOBARAENSE

Transglutaminase (TGase) was separated from the culture broth of an isolated strain of Streptoverticillium mobaraense. The crude enzyme was prepared by centrifugation, ultrafiltration, precipitation by alcohol, centrifugation and freeze‐drying. The yield after these processes was 65–70%. Then the enzyme was purified to homogeneity by chromatography on CM‐cellulose and Sephadex G‐75 on which the yields were about 70% and 80%, respectively; the purified folds reached 2.5–4.7 and 1.08–2.06, respectively. The molecular weight of this TGase was 39,500–40,100 Da by gel filtration chromatography. Optimum enzyme activity was observed in the pH range of 5.0–7.0, and it was maintained stable at 20–40C. The optimal temperature and pH was 52C and 6.0, respectively. At 1 mM and 5 mM metal ion or inhibitors concentration, TGase activity was strongly inhibited by Zn²⁺ and NEM, and not affected obviously by Ba²⁺, Ca²⁺, Co²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Mg²⁺, Mn²⁺, Na⁺ as well as PMSF and EDTA. The effects of these additions on this TGase were compared with those of other microbial TGases.     

Similarity of Stress-Singularity Problems for Materials with Linear and Bilinear Behaviors

An analogy is established between the solutions of the problems of singularities of stresses in linear and bilinear elastic isotropic media. It is shown that the distributions of stresses and displacements in the vicinity of singular points on the boundary of the body (characterized by the singularities of stresses) are described, in both cases, by the same functional dependences on the space coordinates but with different characteristics of the material. We deduce expressions for the effective moduli of elasticity and Poisson's ratio of the bielastic medium including the parameter of hardening of the material. The solution of the problem of singularities of stresses in bilinear materials is obtained from the solution of the corresponding problem for the linear elastic medium by replacing the elastic constants with the corresponding effective values depending on the parameter of hardening of the material. The cases of wedge-shaped notches (for various boundary conditions imposed on their edges), two-component wedges, plane wedge-shaped cracks, and circular conic notches or rigid inclusions in the bielastic space are studied in detail.     

Assessment of a Flexible Architecture for Distributed Control*

Production pipelines of manufactory industries present several machines and robots in which the movements of interpolated axes are managed by computerized numerical controls (CNCs). These are typically synchronized with several other simpler actuators along the pipeline of production. CNCs have to be flexible, easily expandable, and reusable, when pipelines of production are frequently reconfigured to realize different arranged pipelines with different technical requirements. In this paper, the assessment of a flexible CNC for such reconfigurable pipelines is presented. The analysis has been focused on defining objective metrics that can be applied for assessing performance and feasibility of distributed controls for pipelines. The method proposed has been applied on the distributed control architecture defined in the MUPAAC ESPRIT HPCN (Multi Processor Architecture for Automatic Control, High Performance Computer Networking of the European Commission). MUPAAC architecture and prototype has been assessed in order to identify the critical configurations and the limits of the architecture.     

Influence of generator load conditions on third-harmonic voltages in generator stator winding

The influence of changes in load conditions of the generator-transformer unit on the operating conditions of the 100% ground-fault protection of the generator stator winding based on the third-harmonic voltages was analyzed. The analyzed stator ground-fault protection system is by ratio of the voltages third harmonic in generator neutral and at the generator terminals. The third-harmonic voltages were determined on the base of the experimental tests (measurements) run in real conditions at changes in active and reactive load conditions of the generator. It was found that mainly the generator active load influences the voltage feeding the measuring element of ground-fault protection. Therefore, determining operating conditions of ground-fault protection the influence of the generator active and reactive load should be deeply considered. This can ensure the proper operation of the ground-fault protection based on the voltage third harmonics in the whole range of the changes in generator load. Considering the influence of changes in generator load on the third-harmonic voltages (feeding measuring element of the protection system) will allow eliminating irregular generator tripping as a result of unselective operation of these protections.     

Robust autoregressive predictive power control method for mobile CDMA systems

A closed-loop power control (CLPC) scheme with a multistep (indicating multiple prediction steps) linear autoregressive predictor is presented. The proposed CLPC relies on low-rate sample vector based autoregressive prediction. Compared to currently available predictive CLCP schemes, it demonstrates particularly robust performance in the presence of large loop delays and channel estimation errors.     

Effect of Thin Film Thicknesses and Materials on the Response of RTDs and Microthermocouples

Fabrication and thermal characterization of a resistance temperature detector (RTD) heater and microthermocouples (MTs) on silicon substrates have been reported in this paper. The influence of film thickness and nickel-gold (Au) electroplating on RTD on its steady-state temperature with respect to its steady-state electrical power input and resistance is studied. Further, the thermal effects of multiple thermocouples in a thermopile as well as the effects of Au layers in the contact pads of the thermopiles on their open-circuit Seebeck voltage are studied. Therein lies the novelty of this paper. The in situ operating relationships for the RTD heater and the MT are provided     

An Experimental Investigation into the Feed Rate Capacity of Rotary Valve and Blow Tank Feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.     

Highly oriented star-like patterns observed on GaSe epilayers grown on Si(111)

Epitaxial lamellar gallium selenide (GaSe) semiconductors have been grown on trench-patterned silicon (Si) substrates by molecular beam epitaxy. An intriguing star-like patterned morphology was identified by atomic force microscopy on these epilayers. This non-trivial feature can be correlated with the accumulation of stacking faults of two concurrent epitaxial domains around self-oriented triangular pits developed earlier on the Si(111) surface by the chemical etching. Crystallographic considerations show how the stars can be formed.