Preface

Microsystem Technologies -     

Favorable influence of ssDNA-functionalized SWCNT on the navigation pattern of C. elegans

Microsystem Technologies - Single-Walled Carbon Nanotubes (SWCNTs) are widely used as potential carriers in drug delivery systems. The objective of this work was to observe the effects of pristine,...     

Prediction of mode I fracture toughness of unidirectional fibre composites with arbitrary crack fibre orientation from its lowest or matrix fracture tougness

Corrigendum

Prediction of mode I fracture toughness of unidirectional fibre composites with arbitrary crack fibre orientation from its lowest or matrix fracture tougnessby P.K. Sarkar and S.K. Maiti     

Photoelastic Studies on Rubber-to-Rubber Joints

Photoelasticity is a method which yields information on the principal stress difference and orientation in a composite structure. Various problems associated with this technique, especially those concerning the fundamental relationship between the fringe order and the stress, have yet to be investigated. A few studies of this relationship in a universal stress state have been presented, particularly in the field of rubber-to-metal and rubber-to-fabric composites, but no evaluations have so far been made in the field of rubber-to-rubber joints. Applying the photoelastic method, we report our observations on the stress distribution in a natural rubber to natural rubber joint subjected to uniaxial tension. A comparison between the results of experimental photoelastic studies and the corresponding computer modelling has been illustrated. The theoretical displacement pattern of the angular joints of bi-rubber part has also been highlighted.     

Grafting poly(t‐butyl acrylate) to poly(allylamine) by inverse microemulsion radical polymerization: From comb‐polymer to amphiphilic shell crosslinked polymer nanocapsule

An interfacial grafting radical polymerization method for amphiphilic comb copolymer and shell crosslinked polymer nanocapsules was reported. Macropolyradicals on a water soluble long chain polyamine were generated with hydrogen peroxide in the water phase and subsequent grafting radical polymerization of a vinylic monomer at the water/oil interface proceeded at 65°C. In the presence of a crosslinker, the resulting graft copolymer formed a defined core‐shell structure with hydrophilic aqueous core functionalized by the polyamine and a hydrophobic crosslinked polymer shell. The structure of the core‐shell material was characterized by NMR, FTIR, DSC, TGA, SEM, TEM, and the mechanism of the graft polymerization is proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1905–1911, 2007     

Retardation effect of superplasticizer on different cement fractions

Cement hydration is a complex chemical process strongly influenced by the proportions of the various minerals present in the cement, admixtures, and the size of the cement particles. In this note, it is shows that naphthalene based superplasticizer, used at high dosage, does not affect the total heat of hydration but retards the hydration process of portland cement. This retardation, however, is most effective on the medium size fraction of the cement (4 – 30 μm in our case). The superplasticizer does not affect the hydration of the fine fraction (< 4 μm) to that extent due to its richer concentration of SO₃ and alkalies. The coarse fraction of the cement (30 – 72 μm) does not participate (with or without superplasticizer) in the heat evolution process.     

Hydration/dehydration characteristics of struvite and dittmarite pertaining to magnesium ammonium phosphate cement systems

Struvite, an important reaction product in magnesium ammonium phosphate cement systems, was synthesized in the laboratory. The elevated-temperature dehydration and then roomtemperature hydration characteristics of the dehydrated products were studied by thermogravimetric analyses and X-ray diffraction techniques. From isothermal experiments, struvite is found to be thermally unstable in air at temperatures above 50 C. Struvite can lose part or all of its ammonia and water molecules depending on the time and temperature of heat treatment, ultimately forming magnesium hydrogen phosphate. This decomposed product is X-ray amorphous and upon room-temperature rehydration can form struvite, unknown hydrates or newberyite, alone or in combination with each other, depending on the amount of ammonia left in the structure. However, when struvite is heated in excess water, it only loses its water of crystallization to form the monohydrate, dittmarite. Dittmarite is thermally more stable than struvite and like struvite also forms magnesium hydrogen phosphate on decomposition. At room temperature and in the presence of excess water, dittmarite can slowly transform to the hexahydrate, struvite. The consequence of structural similarities between struvite and dittmarite and conditions under which they may be present in cured cements are described.     

Lab-scale feasibility study on new elastomer comprising chloroprene and acrylonitrile for oil and gas applications

The limited options of suitable elastomers with adequate cost-performance balance drive the necessity to introduce new materials in the oil & gas (O&G) application space. The relevance of a recently developed copolymer of chloroprene and acrylonitrile (referred to as acrylonitrile–chloroprene rubber or NCR) to O&G applications is described in this technical contribution. The new elastomer demonstrates adequate physical properties and reasonably good high and low-temperature capabilities. It offers good resistance to several aqueous and non-aqueous fluids with low volume swelling and retains its physical properties to reasonable extents while exposed to hot test oils. Acrylonitrile–chloroprene rubber has been found to sustain “sour gas” exposure. Good abrasion resistance, high tear strength, and remarkably high flex-fatigue resistance coupled with low heat build-up reflect its durability under dynamic conditions. In addition, acrylonitrile–chloroprene rubber can very well withstand the rapid gas decompression test at 25°C. This unique combination of attributes may allow acrylonitrile–chloroprene rubber to be considered as a candidate material for high-performance O&G applications.     

Robustness measure of hybrid intra-particle entanglement,discord, and classical correlation with initial Werner state

Quantum information processing is largely dependent on the robustness of non-classical correlations, such as entanglement and quantum discord. However, all the realistic quantum systems are thermodynamically open and lose their coherence with time through environmental interaction. The time evolution of quantum entanglement, discord, and the respective classical correlation for a single, spin-1/2 particle under spin and energy degrees of freedom, with an initial Werner state, has been investigated in the present study. The present intra-particle system is considered to be easier to produce than its inter-particle counterpart. Experimentally, this type of system may be realized in the well-known Penning trap. The most stable correlation was identified through maximization of a system-specific global objective function. Quantum discord was found to be the most stable, followed by the classical correlation. Moreover, all the correlations were observed to attain highest robustness under initial Bell state, with minimum possible dephasing and decoherence parameters.