Malik Sajjad Mehmood, Asad Muhammad Azam and Tariq Yasin
The present study aims at investigating the effect of incorporating nanoscale MgxNixZn-xFe2O3 (where x=0.15) as nanofillers on the physical and chemical stability of ultra-high molecular weight polyethylene (UHMWPE). The effect of adding 1% and 2% (by weight) nanofillers on the physical and chemical properties of UHMWPE/MgxNixZn-xFe2O3 nanocomposites have also been investigated by using FTIR, Raman, and UV-VIS spectroscopy. FTIR data of UHMWPE/MgxNixZn-xFe2O3 nanocomposites reveal that the addition of MgxNixZn-xFe2O3 up to 1% induces significant chemical and physical structural alterations in UHMWPE matrix. However, this behavior is found to reduce on increasing the concentration of nanofillers from 1% to 2%. Raman spectroscopic data show that crystalline contents of UHMWPE remain unaffected by the addition of nanofillers, however; a significant increase in amorphous contents and decrease in an all-trans interphase region is observed. This behavior is attributed to the chain scission reactions due to the addition of MgxNixZn-xFe2O3 followed by compression molding process at high pressure and elevated temperature. Absorption spectroscopy analysis revealed that the incorporation of MgxNixZn-xFe2O3 results in a decrease of energy band gaps from 2.14eV to 2.08eV (for direct transition) and from 1.54eV to 1.38eV (for indirect transition) due to additional subbandgap energy levels which are induced because of MgxNixZn-xFe2O3 incorporation as nanofillers within the PE matrix.
Abdeen Omer
Over the years, all parts of a commercial refrigerator, such as the compressor, heat exchangers, refrigerant, and packaging, have been improved considerably due to the extensive research and development efforts carried out by academia and industry. However, the achieved and anticipated improvement in conventional refrigeration technology are incremental since this technology is already nearing its fundamentals limit of energy efficiency is described is ‘magnetic refrigeration’ which is an evolving cooling technology. The word ‘green’ designates more than a color. It is a way of life, one that is becoming more and more common throughout the world. An interesting topic on ‘sustainable technologies for a greener world’ details about what each technology is and how it achieves green goals. Recently, conventional chillers using absorption technology consume energy for hot water generator but absorption chillers carry no energy saving. With the aim of providing a single point solution for this dual-purpose application, a product is launched but can provide simultaneous chilling and heating using its vapour absorption technology with 40% saving in heating energy. Using energy efficiency and managing customer energy use has become an integral and valuable exercise. The reason for this is green technology helps to sustain life on earth. This not only applies to humans but to plants, animals and the rest of the ecosystem. Energy prices and consumption will always be on an upward trajectory. In fact, energy costs have steadily risen over the last decade and are expected to carry on doing so as consumption grows. Refrigerants such as hydrochlorofluorocarbons (HCFCs) are present in the ground source heat pump (GSHP) systems and can pose a threat to the environment through being toxic, flammable or having a high global warming potential. However, new types and blends of refrigerant with minimal negative impacts are being developed. A correctly fitted system will also greatly reduce the potential for leakage, which is why using a professional installer is highly recommended. Significant CO2 savings can be gained by displacing fossil fuels. Even compared to the most efficient gas or oil condensing boilers, a well-designed heat pump with COP of 3-4 will reduce emissions by 30-35%. Further carbon savings can be made if the electricity used to power the pump comes from a renewable energy source such as photovoltaic or a renewable electricity tariff. Also, measures can be taken to reduce the impact of pollution from using grid electricity generated through fossil fuel. For example, one can purchase dual tariff green electricity from a number of suppliers. However, even if ordinary grid electricity is used to run the compressor, the system will still produce less CO2 emissions than even the most efficient condensing gas or oil boiler with the same output. The term “vapour compression refrigeration” is somewhat of a misnomer, it would be more accurately described as ' vapour suction refrigeration'. Vapour compression is used to reclaim the refrigerant and is more aptly applied to heat pumps. Vapour compression refrigeration exploits the fact that the boiling temperature of a liquid is intimately tied to its pressure. Generally, when the pressure on a liquid is raised its boiling (and condensing) temperature rises, and vice-versa. This is known as the saturation pressure-temperature relationship.
Bal Chandra Yadav, Rakesh K Sonker, Anjali Sharma, Punit Tyagi, Vinay Gupta and Monika Tomar
ZnO doped SnO2 thin films of various compositions were deposited on the surface of a corning substrate by dropping the two sols containing the precursors for composite (ZSO) with subsequent heat treatment. The sensor materials used for selective detection of nitrogen dioxide (NO2) were designed from the correlation between the sensor composition and gas response. The available NO2 sensors are operative at a very high temperature (150-800°C) with low sensing response (2-100) even in higher concentrations. Efforts are continuing towards the development of NO2 gas sensor aiming with an enhanced response along with a reduction in operating temperature by incorporating some catalysts or dopants. Thus in this work, a novel sensor structure based on ZSO nanocomposite has been fabricated using the chemical route for the detection of NO2 gas. The structural, surface morphological and optical properties of prepared films have been studied by using X-ray diffraction (XRD), Atomic force microscopy (AFM), Transmission electron microscope (TEM) and UV-visible spectroscopy respectively. The effect of thickness variation from 230nm to 644nm of ZSO composite thin film has been studied and the ZSO thin film of thickness ~460nm was found to exhibit the maximum gas sensing response ~2.1×103 towards 20ppm NO2 gas at an operating temperature of 90°C. The average response and recovery times of the sensor were observed to be 3.51 and 6.91 min respectively. Selectivity of the sensor was checked with the cross-exposure of vapour CO, acetone, IPA, CH4, NH3, and CO2 gases. It was found that besides the higher sensing response towards NO2 gas, the prepared ZSO thin film was also highly selective towards NO2 gas.
Sonia Nain and Dinesh Kumar
Carbon nanotubes (CNT) reinforced metal-based composites have become an important area of interest to researchers across the world due to the need for materials with unique properties. Metallic nanoparticles particularly noble metals such as silver (Ag) possess properties such as electrical and thermal conductivity that are far superior to their bulk counterparts. Silver has the highest electrical conductivity among all the metals by virtue of which Ag nanoparticles are considered as very promising candidates in flexible electronics silver/CNT nanocomposites have been fabricated using physical mixing method. Surface morphological studies have revealed that CNT’s are uniformly distributed into the silver matrix. Fabricated samples have been subjected to sintering for 12 hrs at 800oC. Effect of sintering on the electrical conductivity of the Ag/CNT samples is then analyzed. The electrical conductivity of both single wall carbon nanotube (SWCNT) and multiwall carbon nanotubes (MWCNT) reinforced silver nanocomposites increased appreciably upon sintering.
Jothi Narayanan
Conducting biopolymer membrane, which were made by bovine skin collagen doped with metal (Pt,WC). Collagen has great potential in the field of biomaterials. It is a major structural component of connective tissues. Collagen has a unique structure size and amino acid sequence. The collagen molecule consists of three polypeptide chains twined around one another as in a three-stranded rope. Each chain has an individual twist in the opposite directions. The principle feature that affects helix formation is the high content of glycine and amino acid residues. The strands are held together primarily by hydrogen bonds between adjacent-co and –H groups and also by covalent bonds. It has important applications in prosthesis, artificial tissue, drug carrier and cosmetics. Collagen is a biodegradable, biocompatible, non-toxic, and low cost polymer, which shows many interesting properties, such as wound healing, ion-exchange ability and absorption of metal ion. An application of biopolymers in electrical devices is not only interesting but also essential for environmental safety. Collagen is a biomaterial as well as nanowire. The collagen based thin films are responding with electrical conductivity. collagen biopolymers conducting material by doping with molecular charge of donors and acceptors (metal catalyst) and characterizing the nature of the optical band formation and also preliminarily investigation of its electronic transport properties, such as electron hopping and surface morphology.
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