1,724,173 research outputs found
Guest-host effect of dyes in polymer dispersed liquid crystals
No full textThe guest-host [GH) effect of a tetracyanoquinodimethane (TCNQ) dye in nematic liquid crystals (LC) and polymer dispersed liquid crystals (PDLC) has been studied and compared with commercial azo and anthraquinone dyes. The adduct (MORPIP) is a conjugated molecule with a high dipole moment of 15 Debyes. E7 LC doped with MORPIP was found to give a dichroic ratio of 2.34 and an order parameter of 0.31; these values are lower than for the other dichroic dyes, typically 0.6 - 0.78. However, MORPIP showed a useful property When doped in LC and PDLC samples. The rise time of E7 was decreased by 21% when doped with 0.3 wt% MORPIP. It was suggested that MORPIP increased the dielectric anisotropy of E7 and hence reduced the rise time. Nevertheless, no change in dielectric anisotropy was observed. This observation favours a model in which the dipolar dopant reorients rapidly in the applied field and drives the reorientation of the surrounding LC The effects of the dyes incorporated in PDLGs were also studied, in order to explore their suitability for use in a colour reflective display. Dichroic PDLQ were made using the photo-initiated phase separation method. 0.37 wt7o MORPIP doped PDLCs showed a 45% faster response to an applied electric field than that of the undoped PDLCs. However, the contrast ratio of the dichroic PDLCs was not sufficiently high for display use due to insufficient scattering and dye trapping. Two new fabrication methods were developed to overcome this problem One method involved the preparation of a network type PDLC into which a doped LC was dispersed. Another method involved the preparation of voids by removing the LC from the PDLC In both methods, subsequent re-filling of the doped LC into the pre-made polymer matrix improved the contrast ratio and reduced the decay time of the dichroic PDL
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Atomic Force Microscopy and X-Ray Photoelectron Spectroscopy Study on the Surface and Interface States of Liq and ITO Films
No full textAn understanding of the surface and interface states of the organic material and the underlying andoe material is meaningful for organic light-emitting devices (OLEDs). The 8-Hydroxyquinolinolatolithium (Liq) was deposited on indium-tin-oxide (ITO) coated glass by traditional vacuum evaporation.The thickness of Liq is about 120nm. The morphology, surface and interface electron states of the Liq and the underlying ITO have been investigated with the utilization of the atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) technology. AFM observation indicated that Liq grows in the shape of an asymmetrically-distributed island, with each island resembling a round hillock and different size. The Liq film is not very uniform and teemed with many pinholes and cracks.The analysis on XPS spectra of the surface of the Liq/ITO samples shows that, the core-levels of Li1s, C1s, N1s, O1s, In3d5/2, and Sn3d5/2, spectra slightly shift towards lower binding energy with the increase of the sputtering time, which may be caused by the effect of oxygen, indium and tin in ITO diffusing into Liq layer and the argon ions beam with energy. Coordination bond between Li atoms and N atoms does not exist in Liq, which is the main reason why Liq is the blue electroluminescent material. The C atoms mainly bond to C, N and O atoms, forming C-C, C-N=C and C-O bonds, respectively. And there is a speculation of the existence of contaminated C atoms in the surface of ITO, while the O atoms basically originate from quinolate rings and the absorption of O2 and H2O. At the interface N and O, In and Sn interact to some extent, which probably affects the emitting colour of Liq based OLEDs. The analysis of surface of In3d and Sn3d spectrum by XPS provides additional evidence of the existence of cracks and pinholes in Liq layer, leading to much absorption of air molecules.</jats:p
INGLIZ VA O'ZBEK TILLARIDA BOLALAR KASALLIKLARIGA BOG`LIQ TERMINLAR
No full textDavolash jarayoni terminlarsiz tasavvur etib bo`lmaydigan jarayon hisoblanadi. Ushbu maqolada bolalar kasalliklariga bog`liq ayrim terminlarning ingliz va o`zbek tilidagi ko`rinishlari muhokama etiladi
Jamiyatdan ajratish bilan bog`liq bo`lmagan jazolar tizimida harbiy yoki maxsus unvonlardan mahrum qilish jazosi
No full textMazkur maqolada jazo tizimi va uning asosiy xususiyatlari, shuningdek, shaxsni jamiyatdan ajratish bilan bog`liq bo`lmagan jazolar tizimida harbiy yoki maxsus unvonlardan mahrum etish jazosining qo`llash tartibi hamda asoslari atroflicha muhokama qilingan. Shuningdek, mazkur jazoni tayinlash bilan bog`liq holatlar yuzasidan xorijiy tajriba asosida tahlil etilgan
Development of an efficient method for isolation and purification of bioactive Compounds from panax ginseng and rhodiola rosea using high performance counter current chromatography
No full textThis Thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.Traditional Chinese medicine has developed for several thousands of years and accumulated an abundant amount of human pharmacological information and experience as a large potential resource in drug discovery and development. Panax ginseng C. A. Meyer and Rhodiola rosea are both popular herbs worldwide and have many potential pharmacological effects including adaptogenic, antistress, and vasodilating, anticancer and anti-inflammatory. To improve the isolation and separation effect of the two traditional Chinese herbs for quantity and quality control herbal products in general, Separation and purification techniques using high performance counter-current chromatography (HPCCC) are widely applied for this purpose. High performance counter-current chromatography (HPCCC) is a form of liquid liquid chromatography with the higher “g” ” field, which the Brunel Institute for Bioengineering (BIB) team have developed to process scale. It would provide not only more rapid and high throughout isolation and purification process of crude sample, but also relatively simply volumetric and linear scale-up between all scales instruments. A rapid and convenient method for the separation and purification of five ginsenosides from crude sample of Panax ginseng by high-performance counter-current chromatography was successfully developed. One gradient method in normal phase mode was applied for the first separation step for the isolation of ginsenosides using a Spectrum CCC (73 ml coil volume, 1.6 mm bore) with an EtOAc/BuOH/aqueous 5mM ammonium acetate solvent system. The composition ratio of mobile phase changed from 3.5:0.5:4 (v/v) to 2.5:1.5:4 (v/v). Ginsenosides Rd, Rg1 and Rb1 were separated in less than 120 minutes with purities of 96.3% and 98.6% yield, 88.5% and 95.8% yield, 93.7% and 97.4% yield respectively and ginsenosides Rb2 and Rb3, Re and Rc were co-eluted. The final retention of stationary phase was 77.6%. Methylene chloride/methanol/aqueous 5mM ammonium acetate/isopropanol (6:3:4:3, v/v/v) solvent system was used for the isocratic separation of ginsenosides Re and Rc in the second separation step. The ginsenosides Rb2 and Rb3 have similar structures and properties as they are isomers and their aglycone moieties both belong to the same 20 (S) – protopanaxadiol. They were difficult to isolate using this solvent system. The purity of ginsenosides Re and Rc was assessed by HPLC–DAD to be 97.5% with 98.2% recovery and 92.6% with 96.3% recovery. These purified ginsenosides was identified using commercial reference standard on the HPLC and MS.A simple and efficient high-performance counter-current chromatography method for the simultaneous separation and purification for quantity and quality of the two biological compounds salidroside and tyrosol from Rhodiola rosea extract has been developed and scale up for the first time. The experiment were conducted initially by sample concentration, sample loading volume and flow rate study at analytical scale using a Mini HPCCC (17.7 ml coil, 0.8 mm bore) with a new MTBE/butanol /ACN/water (4:2:4:10 v/v/v) solvent system. Then linearly scaled up to the Midi-HPCCC (923 ml coil volume, 4.0 mm bore). Midi-HPCCC runs produced 28.2mg (purity 93%) of salidroside and 13.1mg (purity 96.5%) of tyrosol from the 1000mg crude Rhodiola rosea extract. with the throughput scaled up 50 times. The results demonstrate that HPCCC operating at the high flow and high “g” field is a reliable strategy for linear scale-up from analytical-scale high-throughput screening to preparative-scale
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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