Modeling and control of flexible space platforms with articulated payloads

The first steps in developing a methodology for spacecraft control-structure interaction (CSI) optimization are identification and classification of anticipated missions, and the development of tractable mathematical models in each mission class. A mathematical model of a generic large flexible space platform (LFSP) with multiple independently pointed rigid payloads is considered. The objective is not to develop a general purpose numerical simulation, but rather to develop an analytically tractable mathematical model of such composite systems. The equations of motion for a single payload case are derived, and are linearized about zero steady-state. The resulting model is then extended to include multiple rigid payloads, yielding the desired analytical form. The mathematical models developed clearly show the internal inertial/elastic couplings, and are therefore suitable for analytical and numerical studies. A simple decentralized control law is proposed for fine pointing the payloads and LFSP attitude control, and simulation results are presented for an example problem. The decentralized controller is shown to be adequate for the example problem chosen, but does not, in general, guarantee stability. A centralized dissipative controller is then proposed, requiring a symmetric form of the composite system equations. Such a controller guarantees robust closed loop stability despite unmodeled elastic dynamics and parameter uncertainties

MITIGATING EFFECTS OF ZINGIBER OFFICINALE AGAINST REPRODUCTIVE TOXICITY INDUCED BY DICHLOROVOS IN MALE RATS

Objective: Aim of this study was to evaluate the effect of Z. officinalein mitigating oxidative damage and reproductive toxicity in the testis, induced by chronic dichlorovos administration in male Wistar rats.Methods: Twenty four adult male Wistar rats were divided into 4 groups of 6 rats in each group. Group I received olive oil (1 ml/ kg bwt/day) and served as control group, while Group II was administered dichlorovos (20 mg/kg bwt/day) and Group III & IV received a combination of dichlorovos (20 mg/kg bwt) andZingiber officinale (ginger) extract (100 & 200 mg/kg bwt) for 45 days. At the end of the treatment period, the rats were sacrificed.Results: The weight of the reproductive organs and serum FSH, LH and testosterone levels were assayed. Lipid peroxidation (LPO) (indexed by MDA) and antioxidants enzymes GSH, SOD, CAT were also analysed. Dichlorovos treatment decreased the weight of testis, epididymis, prostate and seminal vesicle as well as the serumlevels of FSH, LH and testosterone. There was a decrease in the activities of GSH, SOD and CAT as well as an increase in MDA concentration.Conclusion: Co-administration of aqueous extract ofZingiber officinalewith dichlorovos showed protective effect and increases the reproductive organs weight and enhancesserum hormones level along with increased antioxidants activities and reduced lipid peroxidation. This indicates that Zingiber officinale mitigates reproductive toxicity and oxidative damage induced by dichlorovos exposure due to its antioxidant activity in the testes

ANTI-ATHEROSCLEROTIC ACTIVITY OF ELAEOCARPUS GANITRUS ROXB. IN CHOLESTEROL-FED RABBITS

  Objectives: Atherosclerosis was experimentally induced in New Zealand white male rabbits by cholesterol feeding for 120 days for investigating effects of 70% ethanolic Elaeocarpus ganitrus seed extract (EEGS) against atherosclerosis.Methods: Anti-atherosclerotic activity of E. ganitrus extract was evaluated at a dose level of 250 and 500 mg/kg of body weight (p.o). On 121st day, the animals were sacrificed to collect the aorta for determining tissue lipid profile, antioxidant parameters, and histopathological changes. One-way ANOVA followed by Tukey's multiple comparison test was used for the statistical analysis.Results: Aorta of cholesterol-fed rabbits for 120 days showed marked elevation in total cholesterol, triglycerides, and phospholipids. EEGS extract treatment significantly (p≤0.01, ≤0.001) corrected disturbed lipid profile in cholesterol-fed rabbits in a dose-dependent manner during the 60 days of the treatment period. A significant reduction in lipid peroxidation and a considerable raise in glutathione, catalase, and superoxide dismutase levels (p≤0.01, ≤0.001) were accompanied by post-treatment with EEGS extract to cholesterol-fed rabbits. The histopathological modifications such as accumulation of foam cells, atheromatous plaque formation, and lumen size reduction supported the successful induction of atherosclerosis in rabbits. The treated rabbits showed significant protective effect by lowering the deposition of cholesterol and increasing the lumen size compared to cholesterol-fed group.Conclusions: Phytoconstituents such as alkaloids, tannins, flavonoids, steroids, triterpenoids, and carbohydrates in the ethanolic extract may be attributed to effective anti-atherosclerotic and antioxidant activity of plant extract. Our study exhibited that EEGS extract could be a potent herbal therapeutic agent for the treatment of atherosclerosis and hypercholesterolemia-related diseases

ANTI-ATHEROSCLEROTIC AND LIPID LOWERING EFFECTS OF CINNAMOMUM VERUM IN CHOLESTEROL-FED RABBITS

Objective: The present study was designed to investigate the antihyperlipidemic and anti-atherosclerotic activity of 70% methanolic crude extract of Cinnamomum verum bark in high cholesterol-fed diet rabbits.Methods: C. verum extract was administered at a dose level of 200 mg/kg and 300 mg/kg (p. o) daily for 120 d to cholesterol-fed rabbits. Lipid profile in serum and histological changes in heart and aorta were investigated. The statistical analysis was carried out by student's ‘t'test.Results: Plant extract showed a significant decrease in the levels of serum total cholesterol, triglycerides, phospholipids, LDL, VLDL (P ≤ 0.001) in a dose-dependent manner in treated animals. HDL ratio improved overwhelmingly as well as the marked decline was also noticed in the atherogenic index after administration with C. verum extract. Histopathological examinations demonstrated less cholesterol deposits in the aorta and significant increase in lumen size of coronary arteries of high cholesterol diet animals given C. verum compared to the high cholesterol diet animals not given C. verum supplement.Conclusion: The phytochemical analysis of methanol extracts indicated a strong presence of alkaloids, flavonoids, tannins, phenols, saponins and fatty acids may be responsible for the significant hypolipidaemic as well as antiatherosclerotic activity. Our study exhibited that the methanol extract of C. verum bark is a potent hypolipidaemic agent and decreased cholesterol deposition in the aorta and plaque formation process in the coronary artery of high cholesterol diet animals

Development of non-invasive transdermal patch of Emblica officinalis for anti atherosclerotic activity

The present study was designed to formulate matrix type transdermal patches of a potent anti atherosclerotic botanical Emblica officinalis on a mercury substrate and evaluated for physicochemical parameters like thickness, % flatness, weight variation, moisture uptake, moisture content, folding endurance, elongation and drug content values. Further, in vivo drug release was also observed by HPLC in rabbit serum. Four formulations were prepared using different ratio of matrix forming polymers, plasticizer and penetration enhancers. Formulations E-1, E-2, E-3 and E-4 were composed of Ethyl cellulose (EC) and Hydroxypropyl Methylcellulose (HPMC) with the following ratios: 6:4, 7:3, 8:2 and 9:1. In vitro cumulative amounts of the permeated drug were observed 48.53, 55.46, 73.26 and 99.72% in 48 hrs from the four formulations. The release profile of the optimized formulation E-4; r2 = 0.984 (Higuchi) showed that permeation of the drug controlled by a diffusion mechanism. The cumulative amount of the permeated drug after 48hrs from E-4 was 343.95mcg/cm2. Permeability coefficient was calculated 7.16mcg/cm2/hr. Based on physicochemical and in vitro skin permeation studies, E-4 was chosen for further in vivo studies. Blood plasma concentration of E-4 after 48 hrs was 0.2914mcg/cm2. Skin permeation performance and scanning electron microscopic studies revealed that formulation E-4 was found to be better than other formulations and it was selected as the optimized formulation. The skin irritation tests showed negligible erythema and edema. The developed transdermal patches may increase the efficacy of E. officinalis for the therapy of atherosclerosis

Development of non-invasive transdermal patch of Emblica officinalis for anti atherosclerotic activity

The present study was designed to formulate matrix type transdermal patches of a potent anti atherosclerotic botanical Emblica officinalis on a mercury substrate and evaluated for physicochemical parameters like thickness, % flatness, weight variation, moisture uptake, moisture content, folding endurance, elongation and drug content values. Further, in vivo drug release was also observed by HPLC in rabbit serum. Four formulations were prepared using different ratio of matrix forming polymers, plasticizer and penetration enhancers. Formulations E-1, E-2, E-3 and E-4 were composed of Ethyl cellulose (EC) and Hydroxypropyl Methylcellulose (HPMC) with the following ratios: 6:4, 7:3, 8:2 and 9:1. In vitro cumulative amounts of the permeated drug were observed 48.53, 55.46, 73.26 and 99.72% in 48 hrs from the four formulations. The release profile of the optimized formulation E-4; r2 = 0.984 (Higuchi) showed that permeation of the drug controlled by a diffusion mechanism. The cumulative amount of the permeated drug after 48hrs from E-4 was 343.95mcg/cm2. Permeability coefficient was calculated 7.16mcg/cm2/hr. Based on physicochemical and in vitro skin permeation studies, E-4 was chosen for further in vivo studies. Blood plasma concentration of E-4 after 48 hrs was 0.2914mcg/cm2. Skin permeation performance and scanning electron microscopic studies revealed that formulation E-4 was found to be better than other formulations and it was selected as the optimized formulation. The skin irritation tests showed negligible erythema and edema. The developed transdermal patches may increase the efficacy of E. officinalis for the therapy of atherosclerosis

Occurrence of the snapper Paracaesio sordida Abe & Shinohara, 1962 from north-west coast of India

Paracaesio sordida Abe & Shinohara 1962, the dirty ordure snapper (Family: Lutjanidae), has a wide distribution in the tropical waters with its occurrence reported from Western Central Pacific and the Indian Ocean. From Indian waters, this species has been previously reported along the east coast, Lakshadweep and from Mangalore in the west coast

Neutron diffraction study of the inverse spinels Co2TiO4 and Co2SnO4

We report a detailed single crystal and powder neutron diffraction study of Co2TiO4 and Co2SnO4 between the temperature 1.6 and 80K to probe the spin structure in the ground state. For both compounds the strongest magnetic intensity was observed for the 111 M reflection due to ferrimagnetic ordering, which sets in below TN 48.6 and 41 K for Co2TiO4 and Co2SnO4, respectively. An additional low intensity magnetic reflection 200 M was noticed in Co2TiO4 due to the presence of an additional weak antiferromagnetic component. Interestingly, from both the powder and single crystal neutron data of Co2TiO4, we noticed a significant broadening of the magnetic 111 M reflection, which possibly results from the disordered character of the Ti and Co atoms on the B site. Practically, the same peak broadening was found for the neutron powder data of Co2SnO4. On the other hand, from our single crystal neutron diffraction data of Co2TiO4, we found a spontaneous increase of particular nuclear Bragg reflections below the magnetic ordering temperature. Our data analysis showed that this unusual effect can be ascribed to the presence of anisotropic extinction, which is associated to a change of the mosaicity of the crystal. In this case, it can be expected that competing Jahn Teller effects acting along different crystallographic axes can induce anisotropic local strain. In fact, for both ions Ti3 and Co3 , the 2tg levels split into a lower dxy level yielding a higher twofold degenerate dxz dyz level. As a consequence, one can expect a tetragonal distortion in Co2TiO4 with c a lt; 1, which we could not significantly detect in the present wor

Numerical simulations of complex fluid-fluid interface dynamics

Interfaces between two fluids are ubiquitous and of special importance for industrial applications, e.g., stabilisation of emulsions. The dynamics of fluid-fluid interfaces is difficult to study because these interfaces are usually deformable and their shapes are not known a priori. Since experiments do not provide access to all observables of interest, computer simulations pose attractive alternatives to gain insight into the physics of interfaces. In the present article, we restrict ourselves to systems with dimensions comparable to the lateral interface extensions. We provide a critical discussion of three numerical schemes coupled to the lattice Boltzmann method as a solver for the hydrodynamics of the problem: (a) the immersed boundary method for the simulation of vesicles and capsules, the Shan-Chen pseudopotential approach for multi-component fluids in combination with (b) an additional advection-diffusion component for surfactant modelling and (c) a molecular dynamics algorithm for the simulation of nanoparticles acting as emulsifiers.Comment: 24 pages, 12 figure