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Molecular Modeling of Cell Adhesion Peptides on Hydroxyapatite and TiO<sub>2</sub>Surfaces: Implication in Biomedical Implant Devices

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Journal of Biomaterials and Nanobiotechnology 2013年第4期4卷 351-356页

作者： Subhashis Biswas Udo Becker Department of Chemistry Narula Institute of Technology Westbengal University of Technology Kolkata India Department of Earth and Environmental Sciences University of Michigan Ann Arbor USA.

Molecular modeling as a tool in studying peptide-substrate interactions provides insight on peptide adsorption conformation, adsorption energy, and stability of the peptide-inorganic interface. This work investigates the hydration and interaction of cell-adhesion peptides, specifically RGD and YIGSR, with the hydroxyapatite surface and TiO2 surface in cluster and periodic boundary condition approaches. The comparison of adsorption energies of RGD and YIGSR on both Hydroxyapatite (HA) and TiO2 surfaces reveals the similarities in adsorption energy and orientation pattern of peptides on both surfaces. The models demonstrate that initial peptide orientation affects adsorption energy for both. YIGSR is consistently more strongly adsorbed to HA-(001) surfaces and steps than RGD for both the surfaces. In addition, RGD maintained its “hairpin”-like structure during adsorption on a flat HA-(001) surface, and a slightly “relaxed hairpin” structure on TiO2 (110) surface. Adsorption energies of RGD on TiO2 (110) surface are significantly more favorable compared to HA-(001) surface, suggesting potential role of TiO2 as biomedical implants when tissue regeneration occurs via cell signaling.

关键词： Hydroxyapatite Nanobiomaterial Bone-Tissue Engineering RGD TiO2

INITIATION OF SHELL MOTION ON SAND BEDS: AN EXPERIMENTAL STUDY

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International Journal of Sediment Research 2002年第4期17卷 286-297页

作者： Subhasish DEY,Alok KUMAR Department of Civil Engineering Indian Institute of Technology Department of Civil Engineering Indian Institute of Technology Associate ProfessorKharagpur 721302 westbengal India.Fax:+*** Student Kharagpur 721302 West Bengal India

Experimental study on initiation of bivalve shell motion on a horizontal sand bed, under a unidirectional flow of water, is presented. Experiments were carried out in a flume with three types of bivalve shells, namely Coquina Clam, Cross-barred Chione and Ponderous Ark, to test the condition for initiation of motion. The shape parameters of bivalve shells are defined appropriately. Experiments were conducted in a flume with a horizontal bed, and the critical shear stresses were estimated using Vanoni's side-wall correction. The characteristic parameters affecting the initiation of shell motion on a horizontal bed in rough-turbulent regime identified based on the physical reasoning and dimensional analysis are the Shields parameter (nondimensional critical shear stress), nondimensional competent mean velocity, nondimensional sand roughness, nondimensional flow depth and shape parameter. Equations of Shields parameter and nondimensional competent mean velocity for the initial movement of shells on a horizontal sand bed with convex upward and downward conditions are obtained using experimental data.

关键词： Bivalve shells Incipient motion Sediment transport Coastal sediment Hydrodynamics Threshold motion

Efficacy of oxytetracycline and potentiated sulphonamide oral therapies against Aeromonas hydrophila infection in Nile tilapia Oreochromis niloticus

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Journal of Coastal Life Medicine 2017年第9期5卷 371-374页

作者： Thangapalam Jawahar Abraham Anwesha Roy Roy Beryl Julinta Jasmine Singha Prasanna Kumar Patil Department of Aquatic Animal Health Faculty of Fishery SciencesWest Bengal University of Animal and Fishery SciencesChakgariaKolkataWestBengalIndia Central Institute of Brackishwater Aquaculture Indian Council of Agricultural ResearchRaja Annamalai PuramChennaiTamil NaduIndia

Objective: To assess the efficacy of feeds containing approved antibiotics, viz., oxytetracycline (OTC) or potentiated sulphonamide [(sulphamethoxazole-trimethoprim) SMZ-TMP] at 1 g, 2 g, 3 g and 4 g of respective antibiotics/kg feed at 2% body weight ration in preventing the Aeromonas hydrophila (A. hydrophila) infection in Oreochromis niloticus. Methods: Commercial pellet feed was top dressed with respective antibiotics using 5 mL vegetable oil as a binder. Fish were injected intramuscularly with A. hydrophila at ≈ 6.0 × 107–8.6 × 107 CFU/fish, and fed subsequently with OTC and SMZ-TMP feeds for 10 and 5 days, respectively. Fish mortalities were recorded during the pre-treatment, treatment and post-treatment periods. Results: Highest mortalities (7.42%–8.33%) were observed in challenged and untreated fish. The mortalities observed in fish fed with OTC or SMZ-TMP were 0%–6.66% with decreasing concentrations of antibiotics from 4 to 1 g/kg feed. Significant differences existed in the mortalities among fish fed with different doses of antibiotics (P < 0.05). The relative percent survival values were 20, 40, 40 and 60 for 1 g, 2 g, 3 g and 4 g OTC/kg feed groups, respectively;while in SMZ-TMP fed fish, the respective relative percent survival values were 10, 100, 100, and 100. Conclusions: The fish fed with feed containing 2 g antibiotic/kg at 2% body weight was the lowest concentration that recorded significantly lower mortality (P < 0.05), which could be the treatment of choice for the control of A. hydrophila in Oreochromis niloticus in tropical condition.

关键词： Aeromonas hydrophila Oreochromis niloticus Oxytetracycline Potentiated sulphonamide

Study of a crop-pest-natural enemy model with Z-type control——An approach to pest management

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International Journal of Biomathematics 2023年第4期16卷 175-207页

作者： Dibyendu Sekhar Mandal Sudip Samanta Rana D.Parshad Abdennasser Chekroun Mohamed Helal Joydev Chattopadhyay Department of Mathematics AmityUniversity Maharashtra Mumbai Maharashtra 410206India Agricultural and Ecological Research Unit Indian Statistical Institute 203B.T.Road Kolkata 700108India Department of Mathematics Bankura University WestBengal722155India Department of Mathematics Iowa State University AmesIA 50011USA Laboratoire d'Analyse Nonlineaire et Mathematiques Appliquees University of Tlemcen Tlemcen 13000Algeria Biomathematics Laboratory Universite Sidi Bel-Abbes P.B.8922000Algeria

In this study,the Z-type control method is applied to an intraguild crop-pest-natural enemy model,assuming that the natural enemy can predate on both crop and pest *** this purpose,the indirect Z-type controller is considered in the natural enemy *** providing the design function for the crop-pest-natural enemy model with Z-control,we find the analytical expression of the update *** findings indicate that the uncontrolled system can produce chaos through perioddoubling bifurcation due to crop over-consumption by the pest *** draw a Poincare map to confirm the occurrence of chaos and compute the maximum Lyapunov *** the observations further indicate that the pest population can be controlled by using an indirect Z-control mechanism in the natural enemy population,we postulate that,if natural enemy abundance can be governed by the update parameter,any desired pest population abundance can be achieved through the proposed Z-type controller,thus controlling the *** verify these assertions,extensive numerical simulations are performed to explore the potential for practical application of the proposed Z-type controller.

关键词： Crop-pest-natural enemy model Z-type control numerical simulations pest control