1,134 research outputs found
Investigating the mechanical properties of nonfunctionalized mwcnt reinforced polymer (pmma) nanocomposites
No Abstract
Synthesis and biological evaluation of dynorphin analogs and, Caco-2 permeability of opioid macrocyclic tetrapeptides
We are interested in the development of potent and highly selective dynorphin (Dyn) analogs targeting kappa opioid receptors (KOR) and studying the pharmacokinetic and physicochemical properties of kappa opioid peptides. In contrast to the extensive structure-activity relationships (SAR) studies on Dyn A, there is minimal SAR information on Dyn B. Therefore we performed an alanine scan of Dyn B amide. The results indicated that Tyr1 and Phe4 residues are critical, while Arg7 is important for maintaining the KOR affinity of Dyn B amide. There is also minimal SAR information for the selective KOR antagonist zyklophin [Nα-benzylTyr1-cyclo(D-Asp5,Dap8)]Dyn A(1-11)NH2 which is active in vivo after systemic administration. Hence, we synthesized linear and cyclic zyklophin analogs using solid phase peptide synthesis. To synthesize cyclic analogs the 5-11 linear fragments were selectively deprotected and cyclized, followed by extension of the peptide chain, coupling of the N-terminal N-alkyl amino acids and cleavage from the resin. We modified a key synthetic step to avoid potential racemization of the N-terminal residue. Pharmacological results suggested that the residue in position 5 has a greater influence on the KOR affinity of zyklophin than the residue in position 8. While Phe4 and Arg6 residues in zyklophin were important for maintaining KOR affinity, surprisingly Tyr1 and Arg7 were not important. The natural product CJ-15,208 (cyclo[Phe-D-Pro-Phe-Trp]) and its D-Trp isomer exhibited KOR activity after oral administration. Therefore, we are investigating the pharmacokinetic and physicochemical properties of these lead peptides. In Caco-2 cell monolayer permeability studies the D-Trp isomer exhibited 7-fold higher permeability in the apical to basolateral direction than CJ-15,208, and the natural product appeared to be an efflux substrate. The permeability of the D-Trp isomer was only 2-fold lower than that of the high permeability compound caffeine. We also examined various agents to solubilize these hydrophobic peptides that are compatible with in vivo studies. The D-Trp isomer had 5- to 40-fold higher solubility than the L-Trp isomer irrespective of the type of solubilizing enhancer used. These studies will help guide the future design of peptidic KOR ligands
Small business owners’ external information-seeking behaviors: The role of perceived uncertainty and organizational identity complexity
This study examines how small business owners’ perceived uncertainty about their environment interacts with the complexity of their organization’s identity to explain their information seeking from external sources. We hypothesize that perceived uncertainty is positively related to external information seeking, and, organizational complexity, in the form of different organizational identities, complicates this relationship and reduces the information seeking in certain conditions while increases in others. The results extend evidence to prior established relationships between perceived uncertainty and information seeking and also suggest that organizational complexity plays an equally important role as a critical moderator. Additionally, we propose a different classification scheme for the external sources and use this to test our hypotheses
EFFECT OF ACETONE SOLUBLE AND ACETONE INSOLUBLE FRACTIONS OF ALLIUM CEPA ON SOME ANIMAL MODELS OF ASTHMA
Current Asthma therapy lack satisfactory effect due to various adverse effects, hence patients are moving to Ayurveda. Researchers conducted studies in last decades on plants mentioned in Ayurveda used for asthama has shown Anti-asthamic, Anti-histaminic and Anti-allergic activity. Present study is conducted to study the anti-asthmatic activity of acetone soluble and insoluble extract of Allium cepa.
In this process dried peels of Allium cepa were immersed in 95% ethanol for 48hr and the extract obtained was further fractionated with anhydrous acetone to get acetone soluble (ASF) and acetone insoluble (AIF) fractions. Effect of the fractions was studied on isolated goat tracheal chain suspended in Kreb’s solution and percentage contractile response was measured. Albino Swiss mice (22-25g) of either sex were subjected to milk- induced leucocytosis and eosinophilia to study adaptogenic and anti-allergic activity respectively. Effects of both the extracts were also studied on clonidine-induced catalepsy and clonidine induced mast cell degranulation in mice as a measure of central and peripheral mast cell stabilization respectively. Wistar rats (150-180g) were used to study effect of fractions on passive paw anaphylaxis to study immunomodulatory and anti-inflammatory activity
A nonlinear control design technique for formation flight of a constellation of satellites
Autonomous control greatly reduces the demand on ground-based resources to keep satellites in a constellation and working reliably, which would be nearly impossible to do without such automation. Linear feedback control is primarily used to counter unexpected small perturbations and to maintain generally sub-optimal trajectories. Linearized approximation of the actual non-linear satellite dynamics cannot predict the "non-local" behavior far from the operating point and certainly not the "global" behavior throughout the state space. The objective of this thesis is development of a formation control and station keeping control laws for a constellation of satellites in a circular orbit. It is shown that by utilizing feedback linearization or nonlinear compensation techniques, an efficient nonlinear control design strategy may be implemented that leads to solutions valid for larger set point regulation, perturbations and station keeping problems. To assess the quality of the proposed control scheme, its performance is compared with that of linear pole placement controller and a nonlinear controller designed using potential function method in a number of simulation case studies. Advantages and disadvantages of the proposed nonlinear control technique are also presented for formation control and station keepin
Assimilation of Intelligent Cloud & IoT based Water Management System and Accumulates Crop Information
Agriculture is a backbone of Indian economy. As India to become a super power, the large development is required in the field of agriculture. Agriculture development will strengthen the Indian economy this will also take small rural areas into limelight and will reduce burden on metros. This project will suggest best irrigation & nutrition management system to the farm and can be remotely operated or controlled by using SMS control. This will provide ideal irrigation conditions by sensing moisture in soil . This helps in preventing drought conditions and water logging also maintains productivity of a soil
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