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  • Author or Editor: M. Alam x
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Abstract  

A series of silicon containing poly(ester imide)s [PEIs] were synthesized using novel vinyl silane diester anhydride (VSEA) and various aromatic and aliphatic dimines by two-step process includes ring-opening polyaddition reaction to form poly(amic acid) and thermal cyclo-dehydration process to obtain poly(ester imide)s. VSEA was synthesized by using dichloro methylvinylsilane and trimellitic anhydride in the presence of K2CO3 by nucleophilic substitution reaction. The PEIs were characterized by FTIR spectroscopy. The thermal properties of PEIs were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The prepared PEIs showed glass transition temperatures in the range of 320–350°C and their 5% mass loss was recorded in the temperature range of 500–520°C in nitrogen atmosphere. These had char yield in the range of 45–55% at 800°C.

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Abstract

A nanostructured mesoporous MCM-41 supported N-heterocyclic carbene–Pd (NHC–Pd) complex was prepared through the reaction of an ionic liquid immobilized onto MCM-41 with palladium acetate. The MCM-41-supported NHC–Pd complex could serve as a highly effective catalyst for the Suzuki cross-coupling reaction under aqueous conditions. Furthermore, the Pd(II) catalyst was recovered by a simple filtration from the reaction mixture and reused without a significant loss of its catalytic activity. The heterogeneous catalyst was also air-stable and thermally stable to allow its easy use.

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Abstract  

The reinforcement of nano-barium titanate in ferrite filled poly-ether-ether-ketone (PEEK) composites caused a shift in the decomposition temperature, at which maximum mass loss occurred, to higher side and enhancement in char yield in thermogravimetric analysis. Loss tangent and glass transition temperature of ferrite filled PEEK composites were also found to be increased with the reinforcement of nano barium titanate. The effect of nano barium titanate on the melting behaviour of ferrite filled PEEK composites was negligible.

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Growing research on beans suggest that they are good for health, as they reduce the risk and/or help in the management of chronic diseases. Beans are valuable parts of several dietary recommendations. Saponins, α-galactosides, phytates, and lectins are currently drawing attention because of their diverse properties, both adverse and beneficial. The aim was to determine the hepatotoxic effect of dry red kidney beans, i.e. Phaseolus vulgaris, on rabbits at 4 g kg–1, 6 g kg–1, and 8 g kg–1 dosing for the period of 30 days. The histopathological examination revealed inflammation of hepatocyte at all three doses along with congestion. The biochemical testing of liver enzymes revealed elevated alanine transaminase (ALT), aspartate transaminase (AST) and gamma-glutamyl transferase (γ-GT). The dose-dependent increase in liver enzymes indicates the hepatotoxic effect of dry red kidney beans, and various studies have demonstrated that lectins are the toxic components responsible for inflammation of body organs.

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Building Information Modelling (BIM) has become an emerging digital technology in the architecture, engineering and construction (AEC) industry. There is a growing demand on applying BIM for sustainable design including the building energy simulation (BES). Lack of sufficient interoperability has caused barriers to utilize the information from BIM for BES. In this study, the interoperability between BIM and four different BES tools (i.e., Ecotect, EQUEST, Design Builder and IES-VE) was explored by using a case study of a residential building in the design stage. The misrepresented information from BIM to multiple BES tools were identified based on six different categories of building information parameters. The research proposed an approach of creating gbXML file with an improved integrity of information in BIM. Overall, this study would lead to further work in developing platforms for improving the information transformation from BIM to BES.

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Abstract  

The concentration of radioactive226Ra,232Th and40K in building and ceramic materials of Bangladesh was investigated by γ-spectrometry with two HPGe detectors. Radium equivalent activities, representative level index values, criterion formula, emanation coefficients and222Rn mass exhalation rates were estimated for the radiation hazard of the natural radioactivity in the materials. The activity concentrations of the natural radionuclides, radium equivalent activities, emanation coefficients and222Rn mass exhalation rates are compared with the corresponding values for building and ceramic materials of different countries. The radium equivalent activities in the samples varied between 30.9 (mosaic stone) and 328.0 Bq·kg−1 (gypsum). The emanation coefficient of the materials ranged from 7.83 (cement) to 33.0% (soil) and the222Rn mass exhalation rate ranged from 2.31 (stone chips) to 118.0 μBq·kg−1·s−1 (gypsum).

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Abstract  

In this paper we present our recent positron annihilation study of the liquid»solid phase boundary for CO2 confined in nanometer pores of VYCOR glass. We find that CO2 remains liquid in the pores far below the bulk freezing temperature and there is pronounced hysteresis between freezing and melting compared to that seen at the gas-liquid boundary in the pores. On freezing we see evidence of open space created in the pores. This leads to complex melting behaviour possibly involving the formation of gas-liquid interfaces. We see that frezing in the pores is totally irreversible, so that any solid which forms (no matter how small) remains stable up to the higher melting temperature. In contrast melting is more reversible (possibly indicating nucleation centres which permit immediate re-freezing). Finally, the pre-frozen state in the pores is different to the post-melted state.

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Abstract  

Polyimides have aromatic moieties in the backbone structure which are responsible for their increased thermal stability. If phosphorus is introduced in the main chain structure of polyimides, there is further improvement in the thermal stability. This has been proved by the work carried out in our group. The polyimide having amine termination can be used for crosslinking of epoxy resins. In the present study amine terminated phosphorus containing nadicimide were taken as curing agent for DGEBA resins. The curing characteristics of DGEBA resin were studied by DSC using different amounts of nadic endcapped phosphorylated amines. DSC thermogram showed the heat of polymerization was lower as compared to system cured with aromatic amines.

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Abstract  

The phase behaviour of carbon dioxide confined in VYCOR glass at pressures below that of the bulk triple point (0.51 MPa) has been investigated. The temperature at which freezing occurs appears to be pressure dependent below 0.3 MPa. As experiments are performed at successively lower pressures, the confined phase transitions gradually disappear, due to either partial pore filling, or the proximity of the confined triple point.

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Abstract  

In confined (nanometer-scale) geometry, the effects of substrate forces and finite size produce a shift of the gas liquid phase boundary from that found in corresponding bulk. The pore transitions also show marked hysteresis. The phase behaviour of a binary gas mixture in confined geometry is likely to depend on the miscibility of the system and the interaction between the substrate and the individual fluid molecules/atoms. Here, we present the results of a pilot positronium annihilation study of the condensation and evaporation of argon-nitrogen mixtures confined in 4 nm diameter cylindrical pores in VYCOR glass.

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