72 research outputs found
The Dynamic Response of Double Bilinear Hysteretic Systems
No full textTitle: The Dynamic Response of Double Bilinear Hysteretic Systems, Author: Birendra Sahay, Location: ThodeAn investigation of the dynamic response of single and two degree of freedom systems with double bilinear hysteric restoring force has been made. The stability of the two systems has also been examined. Numerical integration and Digital-Analog simulation of the system equations of motion has been done using fourth order Runge-Kutta Method and MIMIC simulator to check the approximate analysis.ThesisMaster of Engineering (ME
The optical properties of automatically darkening welding filters based on liquid crystal technology
Get PDFThis thesis addresses the problem of the poor optical angular properties displayed by the majority of automatically darkening welding filters currently on the market that are based on liquid crystal technology. It is shown that by reducing the twist-angle present in the liquid crystal cell to below that of 90 together with employment of a novel polariser arrangement, an optical shutter design based on a double-cell construction is obtained that boasts a reduced angular transmittance variation when in the activated phase. This gives an optical filter possessing a wide central viewing cone whilst maintaining the remaining optical parameters at a high level. The only point of compromise comes from the voltage increase requirement upon reduction of the twist- angle in order to maintain cell contrast. Although this inflates the power consumption of the system, beneficial effects upon the total light scattering provoked by the device are also observed. The final sections deal with a new mode of operation for a twisted-nematic liquid crystal cell when placed between crossed polarisers together with an interference filter possessing a high optical transmittance over the central part of the visible spectrum. This mode of operation means that the cell is in a dark state when inactivated. Application of a small stimulating voltage transmutes the unit into the light state, where upon further increment of the driving electronics beyond this point reverts the system back into a low transmittance phase. Such a mode of operation for a twisted-nematic cell offers several advantages over that of the normally white mode when considering the optical lens of an automatically darkening welding filter. In particular, a dark, fail-safe state is provided should the controlling electronics malfunction preventing the unit from holding in a potentially hazardous light phase, a property usually associated with the normally black mode of operation, whilst the fast switching speed from the light to the dark state associated with the normally white mode of operation is maintained. It is shown that there are only two cell types that display this phenomenon and the optical properties of these two systems are analysed in some detail with the view of developing an automatically darkening welding filter based on this technology. This thesis is submitted to the University of Durham for the degree of Master of Science. All work contained within this thesis was carried out by the author at Hornell Innovation AB in Sweden. No material contained within has been submitted for a previous degree and the copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged
Compression and evaluation of extended release matrix pellets prepared by the extrusion/spheronization process into disintegrating tablets
Get PDFIn this study, a novel approach for compression of matrix pellets into disintegrating tablets has been studied in an attempt to overcome the issues pertaining to rupture of polymer coat during compression of reservoir-type pellets. Extended release matrix pellets were prepared by the extrusion/spheronization technique using commercially available aqueous dispersions of ethyl cellulose, acrylic polymers and sodium alginate at 10%, 20% and 30%w/w levels. Sertraline hydrochloride was used as the model drug and an in vitro release profile of 12 h was targeted. Tablets containing matrix pellets were prepared by the direct compression process. Acceptance Value, a pharmacopeial test, was applied to study the uniformity of drug distribution. Effect of compression force (2-6 kN), extrusion screen aperture size, diluent blend composition and pellet percentage on drug release and acceptance value were studied. As polymer is uniformly distributed within each pellet, the drug release pattern from uncompressed pellets was comparable to compressed tablets. Surface morphological changes due to calcium chloride treatment were observed using Scanning electron microscopy. The pellet segregated from the surface of the tablet was found to be flattened in the direction of applied compression force with minor deformities. In conclusion, matrix pellets can constitute an alternative approach to reservoir-type pellets in obtaining disintegrating tablets for extended delivery of drugs.Nesse trabalho, estudou-se nova abordagem para a compressão de matrizes de péletes em comprimidos desintegrantes, com o intuito de resolver os problemas relativos à ruptura do polímero de revestimento durante a compressão dos péletes do tipo reservatório. Matrizes de péletes de liberação estendida foram preparadas pela técnica de extrusão/esferonização, utilizando dispersões aquosas comercialmente disponíveis de etil celulose, polímeros acrílicos e alginato de sódio a 10%, 20% e 30% p/p. O cloridrato de sertralina foi utilizado como fármaco modelo e focalizou-se no perfil de liberação in vitro de 12 horas. Os comprimidos contendo matrizes de péletes foram preparados pelo processo de compressão direta. O valor de aceitação, teste farmacopéico, foi aplicado para estudar a uniformidade de distribuição do fármaco. O efeito da força de compressão (2-6 kN), o tamanho da abertura de extrusão, a composição da mistura diluente, a porcentagem de pélete na liberação de fármaco e o valor de aceitação foram estudados. Como o polímero é uniformemente distribuído dentro de cada pélete, o padrão de liberação do fármaco dos péletes não-comprimidos foi comparável àquele dos comprimidos. As mudanças morfológicas da superfície devidas ao tratamento com cloreto de cálcio foram observadas utilizando-se a microscopia eletrônica de varredura. O pélete segregado da superfície do comprimido mostrou-se plano em direção à força de compressão aplicada com menores deformidades. Em conclusão, os péletes matriz podem se constituir em abordagem alternativa para péletes do tipo reservatório na obtenção de comprimidos desintegrantes para fármacos de liberação estendida
AZETIDIN-2-ONE FUSED QUINOLINE ANALOGUES: SYNTHESIS AND BIOLOGICAL EVALUATION OF SOME NOVEL 2-CHLORO-3-FORMYL QUINOLINE DERIVATIVES
Get PDFObjective: The aim of the present invention is to synthesize and find out the biological significance of the series of the designed azetidin-2-one fused 2-chloro-3-formyl quinoline derivatives.
Methods: A new series of 2-chloro-3-formyl quinolines derivatives 3-chloro-4-(2-chloro-8/7/6-methoxyquinolin-3-yl)-1-phenyl amino)azetidin-2-one, 3-chloro-4-(2-chloro-8/7/6-chloroquinolin-3-yl)-1-(phenylamino) azetidin-2-one, 3-chloro-4-(2-chloro-8/7/6-methylquinolin-3-yl)-1-(phenyl -amino)azetidin-2-one were synthesized by four steps. The cyclization is facilitated by N-aryl acetamides bearing electron donating groups at ortho-position. However yields of quinolines having electron donating groups in all cases. The structures of the synthesized compounds have been established on the basis of physical and spectral data and are screened for diuretic, some of the exhibited significant activity.
Results: The moderate yield of the proposed compounds was obtained. Spectral analysis and physical characteristic showed that the structural confirmation of the quinoline derivatives of the synthesized compounds. Some of the compounds showed lower to moderate level of significant activities.
Conclusion: From the result of spectral data and diuretic activity it has concluded that the compounds were found to exhibited significance activity
GC-MS Analysis of Methanol and Ethyl Acetate Extract of fruits of Sphaeranthus indicus
No full textIntroduction: To identify the various phytoconstituents present in the plant Sphaeranthus indicus by using gas chromatography and mass spectrometry. Methods: The fruits of Sphaeranthus indicus were extracted with Different solvents of increasing polarity. The methanol and ethylacetate extract were subjected to GCMS analysis to detect the phytoconstituents. Results: Totally 26 compounds were identified. Among these 13 constituents in methanol extract and 13 constituents in ethylacetate extract were identified during the GC-MS analysis. Stigmasterol and lupeol which were identified in the plant is considered to have antiarthritic properties.
Keywords: Sphaeranthus indicus, Gas chromatography, Mass spectrometry
Synthesis and Antimicrobial Activity of Azetidin-2-One Fused 2-Chloro-3-Formyl Quinoline Derivatives
No full textDesign and Synthesis of 7-Chloro-3-Substituted Quinazolin-4(3H)-Ones as Potential Anti-inflammatory and Analgesic Agents
No full textIn our effort to identify potent anti-inflammatory and analgesic agents a number of 7-chloro-3-substituted-2-phenylquinazolin-4(3H)-ones have been synthesized starting from 4-chloro anthranilic acid. Docking analysis of the quinazolinone derivatives were done with COX-II protein which was carried out by means of the AutoDock program. Their structures have been elucidated on the basis of elemental analyses and spectroscopic studies (IR, 1H-NMR, MS). The synthesized compounds were tested for their analgesic activity by tail-flick method and anti-inflammatory activity by carrageenan induced rat paw oedema method. Preliminary evaluation of the anti-inflammatory and analgesic properties of the prepared compounds has indicated that some of them exhibit moderate to significant activity, compared to diclofenac standard.</jats:p
Characterization of hydrothermally synthesized SnS nanoparticles for solar cell application
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