Polydimethylsiloxane based polyurethane and its composite with layered double hydroxide: Synthesis and its thermal properties

This investigation reports the synthesis of a new class of polyurethane (PU) based on bis(hydroxyalkyl) polydimethylsiloxane (PDMS) as diol and isophorone diisocyanate as diisocyanate followed by the preparation of PU/layered double hydroxide (PU/LDH) nanocomposite via ex-situ technique. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy studies confirm the formation of PU and incorporation of PDMS into the PU backbone. Thermogravimetry analysis revealed that thermal stability of the composite improves significantly with incorporation of LDH into the PU matrix. This may be accredited to the barrier effect rendered by the LDH layers. Differential scanning calorimetry study reveals that with the incorporation of LDH, glass transition temperature (T_g) of the composite increases for an optimum level of loading beyond which it remains constant.     

Effect of spheroidized microstructure on the impact toughness and electrochemical performance of a high-carbon steel

The influence of cementite spheroidization on the impact toughness and electrochemical properties of a high-carbon steel has been thoroughly investigated in this study. Heavy warm rolling, followed by 2 h of annealing, has resulted in near-complete spheroidization, leading to a microstructure consisting of nano-cementite globules dispersed in the ultrafine-grained ferritic matrix. The Charpy impact test exhibited superior impact toughness with increased spheroidization. It is validated by the presence of abundant dimples in the fractographs of spheroidized specimens, in contrast to the as-received one that experienced a brittle failure due to its lamellar pearlitic structure. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) carried out in a 3.5% NaCl solution revealed that the corrosion resistance of the alloy gets improved with the increase in the degree of spheroidization. This is attributed to the lower susceptibility of the spheroidized specimen to microgalvanic corrosion owing to the minimum area of contact between nano-spheroidized cementite and ferrite, as elucidated with the help of EIS results aided by equivalent electrical circuit model.     

EFFECTS OF COAL SURFACE CHARGE ON THE ADSORPTION AND GASIFICATION ACTIVITIES OF CALCIUM AND POTASSIUM

ABSTRACT

The electrokinetic properties of lignite, subbituminous and bituminous coal particles and their demineralized derivatives have been measured as a function of pH. Compared to the raw coals, demineTalization generally increased the net negative surface charge densities on the coals. Calcium or potassium adsorption (by ion-exchange) onto the demineralized coals was strongly dependent on pH and the surface charge properties of the coals. Metals uptake was very low (0,1-0.4% wt.) in strongly acidic media (～pHl) but increased dramatically as the net negative charge on the coals was increased by increasing the pHs of the coal suspensions to pH 6 or 10. The reactivities of the calcium- ot potassium-loaded chars in carbon dioxide at 800^°C were similarly dependent upon the pHs at which the catalysts were ion-exchanged onto the coals. For the calcium-containing chars, the reactivities increased in the order: pH 6 > “pH 10 > pH 1 while the variation of the gasification rates with potassium loading pH was: pH 6 ～ pH 10 ? pH I. These findings are attributed to differences in the extent of electrostatic interaction between the calcium or potassium ions and the charged coal surface during catalyst loading from solution.     

An experimental analysis of subcooled leakage flow through slits from high pressure high temperature pipelines

The work presented here is an experimental investigation of the critical flashing flow of initially subcooled water through circumferential slits in pipes. The study provides first hand information about the prediction of leak flow rates in piping and pressure vessels retaining high temperature and high pressure. The dedicated experimental facility loop simulates the thermal hydraulic condition of Pressurized Heavy Water Reactors (PHWR). The critical flow characteristics found for varying leakage cross sections at different stagnation pressure and different degree of subcooling has been demonstrated in this paper. A marked decrease in mass flux has been found as subcooling decreases for a fixed stagnation pressure. More observation has revealed that the tighter slits or openings with very short duct as small as 0.8 cm flow length have different flow behavior than greater opening dimensions or with longer flow channels or that for nozzles. The critical flow has been seen to occur at higher pressure differentials along the flaws and prominent changes in the flow rate is reported to occur with varying dimensional parameters of the slit or cracks.     

Faecal recovery and diurnal variation in excretion of dietary chromium by mature swine

Diurnal variation in faecal excretion of dietary chromium (Cr) was studied in this experiment in mature swine. Five gestating sows weighing between 225 and 250 kg were fed a corn/soya bean meal diet containing 14% crude protein, NRC recommended amounts of vitamins and minerals with a Ca: P ratio of 1.3:1. Chromic oxide was added (0.1% w/w) to the test diet, and ferric oxide was added (0.5% w/w) to the pre-test and post-test diets as dietary markers. Sows received 0.9 kg of the diet twice daily for 8 days. Total faeces from the test diet were collected and a sample of approximately 150 g of morning samples for days 6 to 9 of the experiment was separated. Faecal recovery of dietary Cr was calculated from the total collection and the samples of the 4-day period. It was found that faecal concentration of the Cr varied between days (P < 0.05) and between times of the day (P < 0.05); true equilibrium of Cr excretion was never reached. Diurnal variation in faecal excretion of dietary Cr was shown to exist; Cr concentration was higher in the late morning samples than in the morning samples (P < 0.05). Total faecal recovery of dietary Cr was 93.27%, whereas a greater (P < 0.05) value was obtained by morning sampling (118.76%). A portion of the dietary Cr (6.73%) was retained in the gastrointestinal tract even after 2 days of Cr withdrawal from the diet.     

Adsorption Desalination Quenches Global Thirst

The search for fresh or potable water remains a pressing concern throughout many regions of the world. Although most of the Earth's surface is covered by oceans, the effort to provide for the world's inhabitants with fresh or potable water seems to be insurmountable; at least one billion people do not have access to clean and fresh water. The World Health Organization (WHO) reported that about 41% of the Earth's population lives in water-stressed areas, and the number of people in the water scarce regions may climb to 3.5 billion by the year 2025. Thus, innovative and cost-effective desalination technologies for producing fresh water are needed to provide practical solutions.     

Evaluation of Petroleum Impurities in Motor Spirit and Diesel Oils Using Artificial Neural Network

Studies have been conducted for the ternary mixture of motor spirit, diesel, and kerosene oil samples using artificial neural network (ANN). American standard for testing materials (ASTM) distillation data of samples were used for the evaluation of respective components. Results of such evaluation of the samples were found to comply well with experimental values.     

Impact of Climate Change on Future Flood Susceptibility: an Evaluation Based on Deep Learning Algorithms and GCM Model

Floods are common and recurring natural hazards which damages is the destruction for society. Several regions of the world with different climatic conditions face the challenge of floods in different magnitudes. Here we estimate flood susceptibility based on Analytical neural network (ANN), Deep learning neural network (DLNN) and Deep boost (DB) algorithm approach. We also attempt to estimate the future rainfall scenario, using the General circulation model (GCM) with its ensemble. The Representative concentration pathway (RCP) scenario is employed for estimating the future rainfall in more an authentic way. The validation of all models was done with considering different indices and the results show that the DB model is most optimal as compared to the other models. According to the DB model, the spatial coverage of very low, low, moderate, high and very high flood prone region is 68.20%, 9.48%, 5.64%, 7.34% and 9.33% respectively. The approach and results in this research would be beneficial to take the decision in managing this natural hazard in a more efficient way.

     

Hierarchical Fuzzy Systems Integrated with Particle Swarm Optimization for Daily Reference Evapotranspiration Prediction: a Novel Approach

Water Resources Management - Reference evapotranspiration (ET0) is a crucial element for deriving irrigation scheduling of major crops. Thus, precise projection of ET0 is essential for better...