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Electrostatic phenomena in polyethyleneBlacker, Richard January 1990 (has links)
Measurement of the electrostatic nature of materials is an essential step towards understanding the underlying processes and to the eventual modification of charge behaviour. Indirect monitoring was achieved by resistivity measurements, however, this approach is limited to studying the material and not the electrostatic charge and is, in general, not a satisfactory method. Electrostatic field meters allowed the electrical behaviour of polyethylene to be monitored; its charge accumulation and decay processes were accurately monitored, thus giving a good information base for material modification later in the programme. The use of a data-logging system (based on the Apple//e computer) allowed the manipulation and long term storage of information, whilst giving improved presentation of results. High Density Polyethylene is an intrinsically insulating polymer whose electrostatic properties can be greatly modified by the use of internal antistats. Such additives migrate to a surtace and become effective [at reducing surtace resistivity] over a period of time depending on the diffusivity of the antistat species, and on the external atmospheric conditions, particularly humidity. The effusion of antistat onto a surface was monitored by surtace analysis techniques including X-ray photoelectron scattering, goniometry and infra-red spectroscopy, however, whilst such techniques offered a direct indication of the surtace state and the effect of any surtace modification, electrostatic testing was found to be the most sensitive technique for following antistat action. It is possible to tailor individual antistats to specific applications, however such usage provides only specific protection (fast acting but short lived, or slow acting but long lived). Two single antistat species were combined, and a synergistic effect was obtained for fast acting and long lived systems. It was found that antistats operate by welting (coating) an insulating surtace, and then absorbing atmospheric water vapour, thus lowering the surtace resistivity. Complete surtace coverage is not possible over an HDPE surtace due to its low surtace energy (28mNm'1), however, more complete surtace coverage was achieved by surtace oxidation [raising the polar surlace energy). Natural HDPE is not readily susceptible to surface oxidation; therefore oxidation treatment had only a limited effect. An addition of the fully compatible polymer LLDPE raised the oxidation level and allowed more complete antistat coverage, thereby improving antistatic activity and raising the level of protection gained by using a standard level of antistat. A patent is being taken out covering the use of LLDPE in conjunction with mixed antistat systems.
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Modeling of ion behavior in inward rectifier potassium channels /Robertson, Janice L. January 2009 (has links)
Thesis (Ph. D.)--Cornell University, January, 2009. / Vita. Includes bibliographical references (leaves 192-205).
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Effects of Dialogical Argumentation – Assessment for Learning Instructional Model on Grade 10 Learners’ Conceptions and Performance on Static ElectricityHlazo, Noluthando January 2021 (has links)
Philosophiae Doctor - PhD / This study examined the effects of using Dialogical Argumentation and Assessment for Learning
as an Instructional Method (DAAFLIM) in teaching static electricity focussing on lightning as an
example of static electricity to Grade 10 learners. Three groups of learners from two township
schools were used as a sample for the study. The Solomon three-group design was employed in
collecting data. One class was used as the experimental group and the other two were the control
groups: control 1 group and control 2 group.
The study drew on theoretical frameworks associated with prior knowledge of learners such as the
constructivist viewpoint. The frameworks that were applied in the analysis of the data were
Toulmin’s Argumentation Pattern (TAP) and Ogunniyi’s Contiguity Argumentation Theory
(CAT). The experimental group and control group 2 were exposed to DAAFLIM as a teaching
method and AFL as the assessment strategy. The control 1 group was taught in the traditional
chalk- talk method and assessment was mostly summative. The experimental and control 1 groups
received pre-tests and also wrote a post-test whereas the control 2 group only wrote the post test.
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Optimal determination of steric mass action model parameters for beta-lactoglobulin using static batch experimentsBarz, T., Loffler, V., Arellano-Garcia, Harvey, Wozny, G. January 2010 (has links)
No / In this work, parameters of the steric mass-formalism SMA are optimally ascertained for a reliable determination of the adsorption isotherms of beta-lactoglobulin A and B under non-isocratic conditions. For this purpose, static batch experiments are used in contrast to the protocols based on different experimental steps, which use a chromatographic column. It is shown that parameters can already be determined for a small number of experiments by using a systematic procedure based on optimal model-based experimental design and an efficient NLP-solver. The in different works observed anti-Langmuir shape of the isotherm for small concentrations of beta-lactoglobulin A was corroborated. Moreover, we also found indications for a porosity variation with changing protein concentrations.
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Exploring static electricity as design material for woven and hand-tufted textilesKATSAROU, STELLA January 2014 (has links)
“Electrostatic textile surfaces” is a design example of surfaces which have the ability to interact to human action by movement. The design exploration was directed by the intention of achieving movement through static electricity. During this project textile techniques such as weaving and hand-tufting have been explored in combination with unconventional materials and functions and used as methods to design the surfaces. The findings from the design process regard the categorization of the yarns through the material exploration, the development of a design method through the experimentation of the technique and the surface appearance through the materialization of the method. The two final surfaces are exhibited horizontally and vertically in relation to the ground. The scale of the final structures is related to the body scale. One can electrify the surfaces by walking around or through them letting an open dialog to take place depended on personal interpretations. / Program: Master Programme in Fashion and Textile Design
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Surface charges contribution to protein stability of Thermococcus celer L30e. / CUHK electronic theses & dissertations collectionJanuary 2010 (has links)
Electrostatic interaction has long been proposed to be an important factor for stabilizing protein. Charge-charge interaction may especially be important to the thermostability of protein, as having more surface electrostatic interactions is one of the common structural features found in thermophilic proteins when compared to their mesophilic homologues. In order to quantitatively investigate the electrostatic contribution to protein stability, two complementary approaches, namely the double mutant cycle approach and pKa shift approach, were carried out. / In the double mutant cycle approach, the coupling free energies of two salt bridges (E6/R92 and K46/E62) and one a long range ion pair (E90/R92) were estimated by using circular dichroism, to find out the thermodynamic parameters of the protein model Thermococcus celer L30e and its charge-to-neutral mutants. It was found that the coupling free energy was temperature independent and was about 3 kJ mol-1 per salt bridge. By using a novel analysis of double mutant cycle of DeltaC p, it was also found that the interaction of salt bridge plays an important role in the reduction of DeltaCp. The temperature independency of coupling free energy and the effect of reducing DeltaCp could explain the general observation very well that thermophilic proteins have highly up-shifted protein stability curves is due to its elevated electrostatic interactions when compared with their mesophilic homologs. / In the pKa shift approach, the native state pKa values of acidic residues were obtained by fitting the side chain carboxyl 13C chemical shifts to microscopic model or global fitting of titrational event (GloFTE), whereas the denatured state pKa values were obtained by conventional pH titration of terminal protected 5-residue glycine-based model peptide. It was found that the surface charge-charge interactions, either attractive or repulsive, were strong and complicated because of the high surface charge density of T. celer L30e. However, the fact that most of the acidic residues have significantly downshifted native state pK a values indicated the surface charge distribution of T. celer L30e is optimized for stabilizing the protein. In addition, we have shown that temperature has negligible effect on pKa values in both native state and denatured state, therefore temperature can only marginally amplify the stabilizing effect in linear manner. / To overcome the unwanted crystallization problem of wild-type T. celer L30e in the low ionic strength neutral pH NMR conditions, which were essential for the pKa shift approach, a quintuple Arg-to-Lys variant was designed to dramatically improve the crystalline solubility, while the surface charges, as well as the structural, thermodynamic, and electrostatic properties, were conserved. It has also shown that electrostatic interaction played a critical role in crystallization at low ionic strength conditions, and arginine residue was especially important in crystal packing because of its high ability of forming salt bridges and hydrogen bonds. / Wild-type T. celer L30e has also shown to have no observable residual structure in the guanidine HC1-induced denatured state, indicating that denatured state of T. celer L30e should not have large effect on the overall protein stability. / Chan, Chi Ho. / Adviser: Kam Bo Wong. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 202-218). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
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Electrostatic interactions and exciton coupling in photosynthetic light-harvesting complexes and reaction centers /Johnson, Ethan Thoreau. January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 184-198).
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A study into the protein/protein interactions involved in HIV-1 capsid assemblyDouglas, Chanel Catherine. January 2007 (has links) (PDF)
Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Feb. 17, 2009). Includes bibliographical references.
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The Relation Among Students& / #8217 / Gender, Socio-economic Status, Interest, Experience And Misconceptions About Static Electricity At Ninth Grade LevelKocyigit, Senkoc 01 December 2003 (has links) (PDF)
This study was designed to identify ninth grade students& / #8217 / misconceptions about static electricity concept and to determine relationship among students& / #8217 / gender, socio-economic status, interest, experience with students& / #8217 / misconceptions about static electricity. For this study, Static Electricity Concept Test (SECT) and Socio-Economic Status, Interest and Experience Questionnaire about Static Electricity (SESIEQ) were developed to assess students& / #8217 / misconceptions related to static electricity and their socio-economic status, interest and experience about static electricity, respectively.
This study was carried out during 2002-2003 spring semester with 1260 ninth grade students from 9 Anatolian and regular high schools in Ç / ankaya and Mamak districts of Ankara.
Findings of the concept test indicated that many students had misconceptions about static electricity. Negative and significant relationships among students& / #8217 / gender, socio-economic status, interest, experience and misconception scores were found. The difference between misconception scores of male and female students was significant in favor of males. However, when the data were analyzed using ANCOVA while controlling students& / #8217 / socio-economic status, interest in static electricity and experience about static electricity, no difference was observed between the misconception scores of male and female students.
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NEGATIVE DIELECTRIC CONSTANT OF PHOTO-CONDUCTING POLYMERS UPON CORONA-CHARGINGYan, Han 04 1900 (has links)
<p>The phenomenon of image blurring on laser-printed or electro-photocopied paper has been discovered since the 1980s. In the 1990s, the problem was confirmed to be associated with the undesired surface conduction along the unique photoconductive polymer surface during the photoconduction process. Other than this, little progress has been made in investigating this phenomenon, due to the limited experimental techniques.</p> <p>In this thesis, the electrical properties of a commercially available photoconductor as a result of Corona charging were studied. Various techniques including vacuum deposition and step-function impedance spectroscopy were employed, to overcome the nature of the photoconductor that prevented the use of conventional techniques such as AC impedance spectroscopy. Negative dielectric constant (NDC) has been prevalently discovered at a broad range of frequencies (below 1Hz and up to 1 MHz) and it was questioned in the form of a physically-impossible inductor. This precipitous sign switch of dielectric constant is found in various areas ranging from physics, chemistry, biology to electronics. The magnitude of the NDC decreased drastically with the decrease of electric field frequency. The system obeyed the proposed free-carrier plasma model with a resonance frequency at MHz level.</p> <p>Commercially available polymeric photoconducting materials showing NDC at extremely low frequency are expected to provide unusual scattering to electromagnetic waves and therefore demonstrate profound implications with reduced cost. It has paved the way for many applications such as inductors in integrated chips without bulky coils and provides an insight into a possible revolution in electronics and photonics.</p> / Doctor of Philosophy (PhD)
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