16 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
No full textThis 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
Characterization of hydrothermally synthesized SnS nanoparticles for solar cell application
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Nanocrystalline Europium doped barium sulphate as an energy independent thermoluminescent dosimeter
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A study of Co-doping effect on thermoluminescence properties of potassium calcium sulphate
No full textRecent development in metal-doped SBA-15 catalyst for heterogeneous catalysis and sustainable chemistry: a mini-review
No full textFor the invention of new advanced sustainable materials for heterogeneous catalysis require control of structural parameter of active sites. Mesoporous silica, especially SBA-15 has some unique and important features such as highly ordered mesopore, greater hydrothermal stability, greater wall thickness, large surface area, and adjustable pore volume. All these properties render it a promising material for catalysis, adsorption, supporting material, biomedical application, and environmental remediation. However, purely SBA-15 lacks acidic characters, which hinder its catalysis capabilities. Therefore, functionalized SBA-15 improves the catalytic activities for versatile applications. Thus, in this paper, we attempted to summarize the synthesis procedures, various functionalization processes, and application of metal modified SBA-15 in organic synthesis, fine chemical synthesis, photocatalysis, and decontamination of water. Furthermore, physicochemical properties, sustainability, and efficacies are discussed in detail for future reference and scope of studies.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Development of Chitosan-Based Nanoemulsion Gel Containing Microbial Secondary Metabolite with Effective Antifungal Activity: In vitro and in vivo Characterizations [Retraction]
No full textKhan MK, Khan BA, Uzair B, et al. Int J Nanomedicine. 2021;16:8203–8219.
The Editor and Publisher of International Journal of Nanomedicine are retracting the published article. An investigation by the Publisher found duplication in images from another article from a different author group. Specifically,
From the published article above, Figure 4, F2 and F3, have been duplicated with the same images for Figure 4D from Yujuan Mao, Xiaolan Chen, Bohui Xu, Yan Shen, Zixuan Ye, Birendra Chaurasiya, Li Liu, Yi Li, Xiaoling Xing & Daquan Chen. Eprinomectin nanoemulgel for transdermal delivery against endoparasites and ectoparasites: preparation, in vitro and in vivo evaluation. Drug Delivery. 2019;26(1):1104–1114. DOI: 10.1080/10717544.2019.1682720.
The authors cooperated with the investigation and provided data associated with the reported study. However, despite the authors’ assistance, a satisfactory explanation for how the images came to be duplicated could not be provided, and the validity of the published work could not be verified. Therefore, the Editor and Publisher are retracting the article and the authors do not agree with this decision.
We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines.
The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”
Efficient One-pot Synthesis of 4 Hydroxy-2H Chromene by heterogeneously catalyzed ZnO NP and mesoporous aluminosilicate catalysts in solvent free condition.
No full text4Hydroxy-2H Chromenes are fused benzopyran rings, an important class of biologically active compounds, widely used as antibacterial, antiviral, antitumor, and anticancer agents. In this present paper, we report the 4 Hydroxy-2H Chromenes synthesis by using two catalysts namely, (i) ZnO nanoparticles and (ii) mesoporous ZnO/AlSBA-15 (7) catalysts. The ZnO NP catalyst was prepared by using leaf extract while ZnO/AlSBA-15(7) catalysts were prepared by the wet chemical route. All catalysts were characterized by XRD, SEM, EDS, FTIR, and N2 sorption techniques. The catalytic activity of the synthesized catalyst was evaluated in the one-pot reaction using aromatic aldehyde and Coumarin, and found to be maximum yield of 81% at temperature 80C, a catalyst dose of 10 mmol %, in time limit of 4h.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
