Radiation crosslinked polyvinyl alcohol/polyvinyl pyrrolidone/acrylic acid hydrogels: swelling,crosslinking and dye adsorption study

Iranian Polymer Journal - Hydrogels were produced from mixtures of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and acrylic acid (AAc) using γ-radiation at doses of 3, 7, and...     

An investigation of naturally ventilated teaching spaces with windcathers in secondary school where site is constrained by noise and air pollution

Built environment consumes the bulk of the UK’s fossil fuel. Schools account for 15% of the public sector’s carbon emissions. Energy efficient building design can play a vital role in achieving the national carbon emission reduction target of 80% by 2050. Natural and mixed mode ventilation is at the forefront of suggested energy efficient strategies for reducing carbon emissions from schools while maintaining good indoor air quality and thermal comfort. However, it is challenging to naturally ventilate many urban school buildings through side openings because of high noise and particulate air pollution. An alternative strategy, such as multi floor operation of windcatchers was assessed in this research as a sole source of fresh air in teaching spaces. Dynamic thermal simulation (DTS) and computational fluid dynamics (CFD) simulations assessed the performance of the adopted natural ventilation (NV) strategy in meeting the approved requirements for fresh air, indoor air quality (IAQ) and summertime overheating. Simulation results show that it is challenging to meet approved guidelines on air quality and thermal comfort, only when windcatchers are employed for ventilation purpose. However, fan assisted ventilation in conjunction with windcatchers provided satisfactory results. Detailed performance assessments using CFD seem desirable to validate DTS based findings.     

Analysis of nonlinear thermal radiation and higher‐order chemical reactions on the non‐orthogonal stagnation point flow over a lubricated surface

A numerical study is performed to discuss the heat and mass transfer on oblique stagnation point flow over a lubricated surface with nonlinear thermal radiation and higher‐order chemical reactions. The problem is formulated using basic conservation laws of mass, momentum, energy, and mass concentration in terms of partial differential equations along with nonlinear boundary conditions. These governing equations are transformed into ordinary differential equations by means of similarity transformations. The system of resulting ordinary differential equations are solved numerically by an implicit finite difference scheme known as the Keller–box method. The quantities elaborated in the problem, such as velocity, temperature, skin friction, and local Nusselt and Sherwood numbers are analyzed for several values of involved parameters. The obtained results are presented through various graphs and tabular data and showed a good agreement with the existing results in the literature, which are the subcases of the present work. The heat transfer rate enhances with nonlinear thermal radiation and mass transfer rate decreases with increasing the order of chemical reaction.     

A Coordinated Navigation Strategy for Multi-Robots to Capture a Target Moving with Unknown Speed

The paper proposes an algorithm for multi-robot coordination and navigation in order to intercept a target at a long distance. For this purpose, a limit cycle based algorithm using a neural oscillator with phase differences is proposed. The state of target is unknown, under the assumption that it is stationary or in motion with constant unknown speed along a straight line. Using the proposed algorithm, a group of robots is intended to move towards the target in such a way that the robots surround it. While moving to the target, self-collision between the robots is avoided. Moreover, a collision avoidance with static obstacles as well as dynamic target is realized. The robots reach the target at a desired distance, keeping uniformly distributed angles around the target. The algorithm is further extended so that a static interception point for the target can be estimated in place of pursuing a dynamic target, which is referred to as a virtual target in this paper. In other words, the robots move towards the virtual target instead of the actual target. The robots ultimately encircle the actual target when they arrive at the virtual target. The effectiveness of the proposed method is verified through simulation results.     

Technical appraisal of solar home systems in Bangladesh: A field investigation

Solar Home System (SHS) based rural electrification has experienced a considerable growth in Bangladesh since the start of the Rural Electrification and Renewable Energy Development Project (REREDP) in 2003. The initial target of 50,000 SHS installations in off-grid areas was achieved within 2.5 years, 3 years ahead of schedule. After achieving a revised target of 200,000 SHSs, ahead of schedule in early 2009, a new target of 1 million SHS installations by 2012 was set. The installation of about 0.5 million systems by March 2010 indicates that the current target may well be achieved before the deadline. The size of the SHS market and its impact on the regeneration of the rural economy make it necessary to investigate the quality and reliability of the installed SHSs, if the continued success of the initiative is to be maintained. This paper reports on the findings from a field-based technical appraisal of SHS installations in Bangladesh. Sixty geographically dispersed installation sites were visited. Physical characteristics of the SHSs and their system components were tested to ascertain compliance with and deviations from the approved specifications. Despite the overwhelming success of the REREDP project, the study revealed various shortcomings. Notable among these are: incompatible and sub-optimal component configurations, faulty installations and a lack of effective quality assurance mechanism. The findings are contextualized and the ways to address the identified shortcomings are discussed.     

Chemical composition, in vitro cytotoxic and antioxidant activities of the essential oil and major constituents of Cymbopogon jawarancusa (Kashmir)

The chemical composition of the hydrodistillate of aerial parts of Cymbopogon jawarancusa, a natural grass considered as major forage for animal nutrition, used in food because of the presence of sufficient concentration of minerals like calcium and potassium was analysed by capillary GC–FID, GC–MS and ¹³C NMR. Seventeen constituents representing 97.8% of the total oil with piperitone (58.6%) and elemol (18.6%) as major constituents were identified. In vitro cytotoxicity of the oil and its constituents on human cancer cell lines THP-1 (leukemia), A-549 (lung), HEP-2 (liver) and IGR-OV-1 (ovary) was evaluated by Sulphorhodamine-B assay. The oil was found to be more potent than its components against cancer cell lines tested with IC₅₀ of 6.5 μg/ml (THP-1), 6.3 μg/ml (A-549), 7.2 μg/ml (HEP-2) and 34.4 μg/ml (IGR-OV-1). Antioxidant activity of oil and its constituents was evaluated by DPPH assay. In conclusion, the results demonstrate potent cytotoxic and antioxidant effects of oil, and its components like piperitone, α-pinene, β-caryophyllene and β-elemene.     

Effect of size and shape of metal particles to improve hardness and electrical properties of carbon nanotube reinforced copper and copper alloy composites

Utilizing the extra-ordinary properties of carbon nanotube (CNT) in metal matrix composite (MMC) for macroscopic applications is still a big challenge for science and technology. Very few successful attempts have been made for commercial applications due to the difficulties incorporating CNTs in metals with up-scalable processes. CNT reinforced copper and copper alloy (bronze) composites have been fabricated by well-established hot-press sintering method of powder metallurgy. The parameters of CNT–metal powder mixing and hot-press sintering have been optimized and the matrix materials of the mixed powders and composites have been evaluated. However, the effect of shape and size of metal particles as well as selection of carbon nanotubes has significant influence on the mechanical and electrical properties of the composites. The hardness of copper matrix composite has improved up to 47% compared to that of pure copper, while the electrical conductivity of bronze composite has improved up to 20% compared to that of the pure alloy. Thus carbon nanotube can improve the mechanical properties of highly-conductive low-strength copper metals, whereas in low-conductivity high-strength copper alloys the electrical conductivity can be improved.     

Transforming rice cultivation in flood prone coastal Odisha to ensure food and economic security

Flash floods leading to complete submergence of rice plants for 10–15 days is one of the major constraints for rice production, mainly in rainfed lowland areas. In India, 30% of the rice growing area (12–14 M ha) is prone to flash flooding with average productivity of only 0.5–0.8 t ha^?1. Coastal Odisha is one of the most flood prone areas of India where the paddy crop in the wet season is often devastated by flash floods, forcing farmers either to discontinue paddy cultivation or to revert to traditional varieties with very low yields. The flood tolerant variety, Swarna-Sub1 (SS1), was introduced through cluster demonstrations in some villages of the Bari block of Odisha in 2013. SS1 seeds were provided to 355 farmers in two villages affected by floods twice in 2013. The majority of the farmers cultivated SS1 in 2013 and about 75% of them persisted with the variety in 2014. There has been a steady and significant increase in paddy cultivation and yields per unit area between 2012 and 2014 and a sharp increase in paddy sales during 2013 and 2014. The present study showed that farmers preferred to cultivate low yielding traditional land races owing to their better flood tolerance and the unavailability of flood tolerant high yielding varieties (HYVs). Traditional varieties gave 30–42% higher yields than non-SS1 HYVs when flooding occurred. SS1 on the other hand offered a significant yield advantage of about twice that of traditional varieties, in both flooding and non-flooding years. There is an additional social advantage of SSI in that famers belonging to scheduled castes in flood prone villages, have greater numbers of plots that are exposed to prolonged floods. Thus they benefit proportionately more from the introduction of SS1.     

Process Optimization and Characterization of Popped Brown Rice

The popping process was optimized for brown rice based on an expansion ratio. A central composite design with interactive effect of three independent variables, including salt content (1–2.5 g/100 g raw material), moisture content (13–17 g/100 g raw material), and popping temperature (210–240°C) was used to study their effects on the expansion ratio of rice using response surface methodology. The experimental values of expansion ratio were ranged from 5.24 to 6.85. On fitting the experimental values of expansion ratio to a second order polynomial equation, a mathematical model with the predictability was developed with the statistical adequacy and validity (p ? 0.05). From the model, the optimal condition including salt content (1.75 g/100 g raw material), moisture content (15 g/100 g raw material), and popping temperature (225°C) were predicted for a maximum expansion ratio of 6.79, which was then proved to be 6.85 through experiment. Raw and popped brown rice were investigated for physical properties including hardness, L*, a*, and b* value, length/breadth ratio, bulk density, and minerals, which showed the significant differences. The optimized popped rice sample was evaluated for structural, spectroscopic, and thermal properties, which showed the significant difference from raw rice.