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Ratan Singh,Raj Kumar,D.P. Singh 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.1
The nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed drugs in the world. Their use as anti-inflammatory, antipyretic, antithrombotic, and analgesic agents is, however, restricted by their adverse effects on gastrointestinal (GI) tract. To overcome this problem with NSAIDs, two new strategies in the development of these drugs are explained. The first approach is the development of selective inhibitors of the enzyme cyclooxygenase (COX)-2, the inducible isoform of the prostaglandin G/H synthetase enzyme. COX exists in two isoforms, viz., COX-1 and COX-2. Selective inhibitors of COX-2 will suppress prostaglandin synthesis at the sites of inflammation, but they will not interfere with the activity of COX-1, in tissues like the GI tract. The use of selective COX-2 inhibitors, however, lacks the cardioprotective effects mediated by COX-1. An alternate approach to reduce the GI toxicity of NSAIDs is the development of nitric oxide (NO)-releasing NSAIDs. It has been reported that NO does not affect the gastroduodenal mucosa and produces the same effects as endogenous prostaglandins. The present article focuses on the NO-releasing NSAIDs, which are from the conventional class of COX-2 inhibitors that have potential clinical applications, as well as some drug candidates still under development.
Temperature-dependent rheological behaviour of methylcellulose nanocomposite organogels
Ratan Pal Singh 한국고분자학회 2023 Macromolecular Research Vol.31 No.1
The temperature-dependent gelation phenomenon of methylcellulose (MC) in the organic solvent N, N-Dimethyl formamide (DMF) is examined for various surfactants using dynamic mechanical analysis under compression technique. The peaks got in the dynamic strain experiment may represent the fluidity in the structure above 60 ℃. Upon further heating, there is an increase in the enthalpy, which involves the arbitrary vibration of free –OCH3 functional groups of MC, resulting in non-polar interactions to build a complex viscous liquid. A vast increment in dynamic strain value manifests the solubility of MC in DMF. During the Scanning electron microscopy (SEM) investigations of dry MC films, the entangled globules-rod conformations are seen. These conformations are capable of absorbing a large amount of energy before the rapture. The spring-like structure of these conformations encourages the MC-DMF gel regime to absorb energy and distribute it among the non-conformational sol–gel area. High storage modulus value signifies a higher crosslink density and a tendency to absorb more vibrational-thermal energy without disintegrating. We investigated the stability of these gels through computational studies, where the potential energy between a single surfactant molecule and the dimeric form of MC is calculated.
Ratan Kumar Ghosh,Aparna (Dey) Ghosh 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.1
The paper presents a study on the effects of soil-structure-interaction (SSI) on the performance of the compliant liquid column damper (CLCD) for the seismic vibration control of short period structures. The frequency-domain formulation for the input-output relation of a flexible-base structure with CLCD has been derived. The superstructure has been modeled as a linear, single degreeof-freedom (SDOF) system. The foundation has been considered to be attached to the underlying soil medium through linear springs and viscous dashpots, the properties of which have been represented by complex valued impedance functions. By using a standard equivalent linearization technique, the nonlinear orifice damping of the CLCD has been replaced by equivalent linear viscous damping. A numerical stochastic study has been carried out to study the functioning of the CLCD for varying degrees of SSI. Comparison of the damper performance when it is tuned to the fixed-base structural frequency and when tuned to the flexible-base structural frequency has been made. The effects of SSI on the optimal value of the orifice damping coefficient of the damper has also been studied. A more convenient approach for designing the damper while considering SSI, by using an established model of a replacement oscillator for the structure-soil system has also been presented. Finally, a simulation study, using a recorded accelerogram, has been carried out on the CLCD performance for the flexible-base structure.
Singh, Ratan,Kumar, Raj,Singh, D.P. The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.1
The nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed drugs in the world. Their use as anti-inflammatory, antipyretic, antithrombotic, and analgesic agents is, however, restricted by their adverse effects on gastrointestinal (GI) tract. To overcome this problem with NSAIDs, two new strategies in the development of these drugs are explained. The first approach is the development of selective inhibitors of the enzyme cyclooxygenase (COX)-2, the inducible isoform of the prostaglandin G/H synthetase enzyme. COX exists in two isoforms, viz., COX-1 and COX-2. Selective inhibitors of COX-2 will suppress prostaglandin synthesis at the sites of inflammation, but they will not interfere with the activity of COX-1, in tissues like the GI tract. The use of selective COX-2 inhibitors, however, lacks the cardioprotective effects mediated by COX-1. An alternate approach to reduce the GI toxicity of NSAIDs is the development of nitric oxide (NO)-releasing NSAIDs. It has been reported that NO does not affect the gastroduodenal mucosa and produces the same effects as endogenous prostaglandins. The present article focuses on the NO-releasing NSAIDs, which are from the conventional class of COX-2 inhibitors that have potential clinical applications, as well as some drug candidates still under development.