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Search Results: 1 - 10 of 417 matches for " Nishata Royan Rajendran Royan "
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Effect of Acid- and Ultraviolet/Ozonolysis-Treated MWCNTs on the Electrical and Mechanical Properties of Epoxy Nanocomposites as Bipolar Plate Applications
Nishata Royan Rajendran Royan,Abu Bakar Sulong,Jaafar Sahari,Hendra Suherman
Journal of Nanomaterials , 2013, DOI: 10.1155/2013/717459
Abstract:
The Effects of Antioxidants Content on Mechanical Properties and Water Absorption Behaviour of Biocomposites Prepared by Single Screw Extrusion Process
Mohd Hafizuddin Ab Ghani,Mohd Nazry Salleh,Ruey Shan Chen,Sahrim Ahmad,Mohd Rashid Yusof Hamid,Ismail Hanafi,Nishata Royan Rajendran Royan
Journal of Polymers , 2014, DOI: 10.1155/2014/243078
Abstract: The performance of hybrid fillers between rice husk and sawdust filled recycled high density polyethylene (rHDPE) with the presence of antioxidants (IRGANOX 1010 and IRGAFOS 169, with the ratio of 1?:?1) was investigated. The biocomposites with 30?wt% of matrix and around 70?wt% of hybrid fillers (rice husk and sawdust) and different antioxidants’ contents (0 to 0.7?wt%) were prepared with single screw extruder. Increasing the amount of antioxidants in biocomposites reduced the modulus of elasticity and modulus of rupture on flexural testing. The addition of antioxidants increased the tensile and impact strength of biocomposites. From the study, samples with 0.5?wt% of antioxidants produce the most reasonable strength and elasticity of biocomposites. Furthermore, the effect of antioxidants content on water uptake was minimal. This might be caused by the enhanced interfacial bonding between the polymer matrix and hybrid fillers, as shown from the morphology by using scanning electron microscopy (SEM). 1. Introduction The large amount of disposable bottles presently produced makes the search for alternative procedures for recycling of these materials imperative. As chemical processing is most often costly and sometimes aggressive to the environment, a possible solution is the recycling of such material by thermomechanical techniques [1]. Great attention has been focused on the addition of natural fibres as reinforcement for plastics, replacing glass fibres and other synthetic materials. This is due to environmental concerns and also for providing a good combination of high performance, great versatility, and processing advantages at lower cost. Some drawbacks reduce the application of natural fibers as reinforcement in polymers, such as the incompatibility between fibres and polymer matrices, the tendency to form aggregates during processing, and the poor resistance to moisture. Incompatibility of components is responsible for poor thermal and mechanical properties. The stress transfer from the matrix to the fibre depends on fibre-fibre and fibre-matrix interactions [2]. To overcome this problem, it is necessary to promote polymer modification with polar groups (such as maleic anhydride or glycidyl methacrylate stearic acid) to enhance the adhesion between the composite components. The coupling agent more often used for this application is a polyethylene graft maleic anhydride (MAPE). Interactions between the anhydride groups of maleated coupling agents and the hydroxyl groups of natural fibres can overcome the incompatibility and increase tensile and
Effects of Dietary Mineral Premix Reduction or Withdrawal on Broilers Performance
A. Jafari Sayadi,B. Navidshad,A. Abolghasemi,M. Royan
International Journal of Poultry Science , 2005,
Abstract: This experiment was conducted to evaluate the effects of withdrawing or reduction mineral premix from diets at 21 to 42 days of age on broiler performance. Two hundred and eighty day old broiler chickens of Cobb 500 strain used in a completely randomized design with 7 treatments, 4 replicates each. Chickens were fed on a common starter diet with suggested mineral premix level (0.5%) for first three weeks age. Seven corn-soybean meal based grower diets with different mineral premix levels were used at 4 to 6 weeks of age. The dietary treatments were the following: T1) 0.5% mineral premix at weeks 4, 5 and 6 T2) 0.5% mineral premix during weeks 4 and 5, and 0.25% at week 6 T3) 0.5% mineral premix during week 4 and 0.25% during weeks 5 and 6 T4) 0.25% mineral premix at weeks 4, 5 and 6 T5) 0.5% mineral premix at weeks 4 and 5 and omitting it during week 6 T6) 0.5% mineral premix during week 4 and removing it during weeks 5 and 6 T7) using diet without mineral premix during weeks 4, 5 and 6. Feed intake and weight gain were measured at the end of each week and feed conversion ratio was calculated. Results showed that reduction or withdrawal of mineral premix from diets in different weeks of grower period, didn`t affect feed intake. In weeks 4 and 5, there was no significant difference in weight gain and feed conversion ratio, but in week 6, weight gain of treatment T1 which fed diet with 0.5% mineral premix at whole the experiment period was significantly higher and its feed conversion ratio was significantly lower than other treatments. The overall results of the present study indicated that it`s possible to reduce or remove dietary mineral premix during at least first 2 weeks of grower period but longer withdrawal can negatively affect weight gain and feed conversion of broiler chickens. This decline in dietary mineral premix maybe causes an increase in cost per kg of produced chickens.
Effects of Conjugated Linoleic Acid, Fish Oil and Soybean Oil on PPARs (α & γ) mRNA Expression in Broiler Chickens and Their Relation to Body Fat Deposits
Maryam Royan,Goh Yong Meng,Fauziah Othman,Awis Qurni Sazili,Bahman Navidshad
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12128581
Abstract: An experiment was conducted on broiler chickens to study the effects of different dietary fats (Conjugated linoleic acid (CLA), fish oil, soybean oil, or their mixtures, as well as palm oil, as a more saturated fat), with a as fed dose of 7% for single fat and 3.5 + 3.5% for the mixtures, on Peroxisome Proliferator-Activated Receptors (PPARs) gene expression and its relation with body fat deposits. The CLA used in this experiment was CLA LUTA60 which contained 60% CLA, so 7% and 3.5% dietary inclusions of CLA LUTA60 were equal to 4.2% and 2.1% CLA, respectively. Higher abdominal fat pad was found in broiler chickens fed with a diet containing palm oil compared to chickens in the other experimental groups ( P ≤ 0.05). The diets containing CLA resulted in an increased fat deposition in the liver of broiler chickens ( P ≤ 0.05). The only exception was related to the birds fed with diets containing palm oil or fish oil + soybean oil, where contents of liver fat were compared to the CLA + fish oil treatment. PPARγ gene in adipose tissue of chickens fed with palm oil diet was up-regulated compared to other treatments (P ≤ 0.001), whereas no significant differences were found in adipose PPARγ gene expression between chickens fed with diets containing CLA, fish oil, soybean oil or the mixture of these fats. On the other hand, the PPARα gene expression in liver tissue was up-regulated in response to the dietary fish oil inclusion and the differences were also significant for both fish oil and CLA + fish oil diets compared to the diets with palm oil, soybean oil or CLA as the only oil source ( P ≤ 0.001). In conclusion, the results of present study showed that there was a relationship between the adipose PPARγ gene up-regulation and abdominal fat pad deposition for birds fed with palm oil diet, while no deference was detected in n-3 and n-6 fatty acids, as well as CLA on PPARγ down regulation in comparison to a more saturated fat. When used on its own, fish oil was found to be a more effective fat in up-regulating hepatic PPARα gene expression and this effect was related to a less fat deposition in liver tissue. A negative correlation coefficient (?0.3) between PPARα relative gene expression and liver tissue fat content confirm the anti-lipogenic effect of PPARα, however, the change in these parameters was not completely parallel.
Avian Community Responses to Variability in River Hydrology
Alexander Royan, David M. Hannah, S. James Reynolds, David G. Noble, Jonathan P. Sadler
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0083221
Abstract: River flow is a major driver of morphological structure and community dynamics in riverine-floodplain ecosystems. Flow influences in-stream communities through changes in water velocity, depth, temperature, turbidity and nutrient fluxes, and perturbations in the organisation of lower trophic levels are cascaded through the food web, resulting in shifts in food availability for consumer species. River birds are sensitive to spatial and phenological mismatches with aquatic prey following flow disturbances; however, the role of flow as a determinant of riparian ecological structure remains poorly known. This knowledge is crucial to help to predict if, and how, riparian communities will be influenced by climate-induced changes in river flow characterised by more extreme high (i.e. flood) and/or low (i.e. drought) flow events. Here, we combine national-scale datasets of river bird surveys and river flow archives to understand how hydrological disturbance has affected the distribution of riparian species at higher trophic levels. Data were analysed for 71 river locations using a Generalized Additive Model framework and a model averaging procedure. Species had complex but biologically interpretable associations with hydrological indices, with species’ responses consistent with their ecology, indicating that hydrological-disturbance has implications for higher trophic levels in riparian food webs. Our quantitative analysis of river flow-bird relationships demonstrates the potential vulnerability of riparian species to the impacts of changing flow variability and represents an important contribution in helping to understand how bird communities might respond to a climate change-induced increase in the intensity of floods and droughts. Moreover, the success in relating parameters of river flow variability to species’ distributions highlights the need to include river flow data in climate change impact models of species’ distributions.
Analytical solution of the concentration and current in the electoenzymatic processes involved in a PPO-rotating-disk-bioelectrode  [PDF]
Govindhan. Varadharajan, Lakshmanan. Rajendran
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.31001
Abstract: A mathematical model for electroenzymatic process of a rotating-disk-bioelectrode in which polyphenol oxidase occurs for all values of concentration of catechol substrate is presented. The model is based on system of reaction-diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reaction. Approximate analytical method (He’s Homotopy perturbation method) is used to solve the non-linear differential equations that describe the diffusion coupled with a Michaelis-Menten kinetics law. Closed analytical expressions for substrate concentration, product concentration and corresponding current response have been derived for all values of parameter using perturbation method. These results are compared with simulation results and are found to be in good agreement. The obtained results are valid for the whole solution domain.
Application of variational iteration method and electron transfer mediator/catalyst composites in modified electrodes  [PDF]
Alagu Eswari, Lakshmanan Rajendran
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.26076
Abstract: The nonlinear coupled system of diffusion equations are solved analytically for the transport and kinetics of electrons and reactant in the layer of a modified electrode. Analytical expressions of concentrations of substrate and mediator are presented using He’s variational iteration method. The approximate expression of current for microheterogeneous catalysis at isonomer or redox polymer modified electrodes is also obtained. The results of the available limiting cases are compared with our results and are found to be in good agreement.
Analytical solution of coupled non-linear second order differential equations in enzyme kinetics  [PDF]
Govindhan Varadharajan, Lakshmanan Rajendran
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.36063
Abstract: The coupled system of non-linear second-order reaction differential equation in basic enzyme reaction is formulated and closed analytical ex-pressions for substrate and product concentra-tions are presented. Approximate analytical me-thod (He’s Homotopy perturbation method) is used to solve the coupled non-linear differential equations containing a non-linear term related to enzymatic reaction. Closed analytical expres-sions for substrate concentration, enzyme sub-strate concentration and product concentration have been derived in terms of dimensionless reaction diffusion parameters k, and us-ing perturbation method. These results are compared with simulation results and are found to be in good agreement. The obtained results are valid for the whole solution domain.
Analytical Solutions of System of Non-Linear Differential Equations in the Single-Enzyme, Single-Substrate Reaction with Non-Mechanism-Based Enzyme Inactivation  [PDF]
Govindhan Varadharajan, Lakshmanan Rajendran
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.29158
Abstract: A closed form of an analytical expression of concentration in the single-enzyme, single-substrate system for the full range of enzyme activities has been derived. The time dependent analytical solution for substrate, enzyme-substrate complex and product concentrations are presented by solving system of non-linear differential equation. We employ He’s Homotopy perturbation method to solve the coupled non-linear differential equations containing a non-linear term related to basic enzymatic reaction. The time dependent simple analytical expressions for substrate, enzyme-substrate and free enzyme concentrations have been derived in terms of dimensionless reaction diffusion parameters ε, λ1, λ2 and λ3 using perturbation method. The numerical solution of the problem is also reported using SCILAB software program. The analytical results are compared with our numerical results. An excellent agreement with simulation data is noted. The obtained results are valid for the whole solution domain.
Analytical Solutions of Some Two-Point Non-Linear Elliptic Boundary Value Problems  [PDF]
Vembu Ananthaswamy, Lakshmanan Rajendran
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.39154
Abstract: Several problems arising in science and engineering are modeled by differential equations that involve conditions that are specified at more than one point. The non-linear two-point boundary value problem (TPBVP) (Bratu’s equation, Troesch’s problems) occurs engineering and science, including the modeling of chemical reactions diffusion processes and heat transfer. An analytical expression pertaining to the concentration of substrate is obtained using Homotopy perturbation method for all values of parameters. These approximate analytical results were found to be in good agreement with the simulation results.
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