Dissertations / Theses on the topic 'Conductivity and resistance matrix'
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Tang, Fei. "The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles." Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/835313-syGDu9/webviewable/.
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Rahi, Khayyun Amtair 1954. "Hydraulic conductivity assessment for a variably-saturated rock matrix." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/191883.
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Water flow through unsaturated rock has received increasing attention recently. In order to solve unsaturated flow problems, it is necessary to determine the unsaturated hydraulic conductivity, K. A model which predicts K from water retention data was evaluated for rock matrices. It includes three unknown parameters to be determined from experimental data. To verify the model, K was measured by the outflow method. Water retention data were determined by two methods, the pressure plate extractor and the psychrometer. Near saturation, the water retention curve was best estimated by the pressure extractor method. The outflow method gave reliable measurements of K at low negative pressure heads (≥ -1000 cm of water). The predicted K deviated from the experimental values when only the water retention data were used to estimate the model parameters. When the measured K was incorporated in the parameter estimation process, the deviation was reduced considerably.
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Li, Ju 1975. "Modeling microstructural effects of deformation resistance and thermal conductivity." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/46283.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2000.Includes bibliographical references (p. 344-360).
This is a study of the microstructural influences on thermo-mechanical behavior of selected metals and ceramics using computer simulation, with original contributions in both theoretical and applied aspects. There are three major thrusts. First, by constructing a many-body empirical potential for ZrCx and then carrying out MD simulations to calculate its lattice thermal conductivity, I obtain the first quantitative evidence ever that the vibrational contribution is only a small part of the total thermal conductivity of refractory carbides at realistic carbon vacancy concentrations. This is a long-standing problem which even the most recent review article on the subject give what I now believe is the wrong estimate. Second, ideal strengths are calculated for Ar,Cu,SiC crystals using both lattice and molecular dynamics methods. A set of homogeneous instability criteria are derived. Tension tests are performed on amorphous and nanocrystalline SiC at room temperature, based on which a grain size cutoff of ~20 nm is extrapolated for the Hall-Petch effect. Nano-indentation is performed on single-crystal and nanocrystalline Cu, and bursts of dislocation loops is observed at a local stress level consistent with recent experiments on Cu thin films. Third, an invariant loop summation similar to the J-integral is derived for the driving force on defect motion, but with the loop size now down to nanometers, and the summation now expressed in terms of interatomic forces instead of stress, a field concept which is hard to use in atomistic calculations and becomes ill-defined when defect separations approach the nanometer scale. It is shown first that the change in a system's total Helmholtz free energy due to a defect's move can be approximated by a local quantity involving only scores of atoms immediately surrounding the defect. Then, perturbation expansion is used to evaluate this local invariant for defect translation using only the current configuration. This driving force measure is then tested on a) self-interstitial diffusion near free surface in [alpha]-iron, b) crack-tip extension near a void in Si, c) screw dislocation translation in Si, with convincing results down to literally r = 1 nm, at a fraction of the cost of a full relaxation or free energy calculation for the whole system. This means that defect mobility can now be characterized by a universal and invariant standard, computable from a tiny atomistic calculation without relying on elasticity formulas or image summations. The standard is then used to determine the true Peierls-Nabarro stress in Si-like materials.
by Ju Li.
Ph.D.
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Chinyamakobvu, Oswald Simbarashe. "Metal matrix composites for abrasive wear resistance." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/46998.
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Adhikari, Amit. "Polymer Matrix Composite: Thermally Conductive GreasesPreparation and Characterization." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556282222035491.
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Alshabbani, Haydar Swiry Rahi. "Metal matrix composites with diamond for abrasion resistance." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22944/.
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Metal matrix composites (MMCs) have been used in many applications (such as automotive, aerospace and construction) for many decades. Recently, there have been interesting developments in this type of composite, applying them in electronic and thermal applications such as with semiconductors, in electronic packaging and heat sinks. This is particularly the case for composites of a metal matrix with diamond which are considered a modern sub-class of metal matrix composites. However, while the thermal properties are exceptional, this class of composites has not been extensively examined for mechanical and tribological behaviour, and it may be possible to apply these composites in practical applications, especially those that require extreme mechanical and tribological strength, for example cutting resistance for security applications. Therefore, this research looks for a composite material consisting of metal matrix and diamond particles, which resists abrasive cutting. This progresses through a series of steps, developing methods to process the material, understanding the mechanics of abrasive behaviour and optimizing the composite structure to resist abrasive cutting. Gas Infiltration (GI) casting under gas pressure has been applied to metal matrices with relatively low melting point (aluminium (Al) and tin (Sn)) to obtain a significant penetration of the metal into a preform of diamond particles. Different diamond particle sizes (63-75, 212-250, 420-500 μm) were used to strengthen the Al matrix and diamond coated with a thin Ti layer was used to attempt to enhance the bonding forces between the aluminium matrix and diamond. Al-1 wt. % Mg as a matrix alloy was utilised to investigate the possible effect of Mg on bonding phases and to reduce the surface tension of molten aluminium during the infiltration process. Epoxy was also used as a matrix with diamond in this research by gravity infiltration. Tribological and microstructural tests were performed on the samples, and the results show that the surface modification (Ti coating) of diamond particles has an important role for enhancing the bonding between the aluminium matrix and diamond reinforcement as is apparent under SEM observation, thus improving wear resistance. The coating layer works to either catalyse the graphitisation of diamond surfaces to then dissolve carbon in the metal, or reacts at the diamond surfaces to form carbide crystallites at the interface. This may be one of the reasons contributing to the bonding between the different matrices and diamond. The presence of some of these phases was indicated with XRD patterns and Raman spectra. The principal characterization method was by abrasion cutting tests, which have been carried out on all the samples made. One particle size range, 420-500 μm, of diamond coated by Ti, has been used to manufacture composites with different matrices (titanium (Ti), nickel )Ni(, copper)Cu(, tin)Sn) and epoxy) using different production methods (PM and SPS) for the transition metal matrices due to their high melting points. The abrasion cutting tests of these composites showed that the bonding between the metal matrix and diamond reinforcement and the processing temperature, have an important role in enhancing the abrasion wear resistance of composites, rather than the hardness of matrices.
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Lee, Jae-Kon. "Thermal cycling and creep resistance of metal matrix composites /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/7103.
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Park, Joon-Soo. "Evaluation Methods for Fracture Resistance of Ceramic Matrix Composites." Kyoto University, 2003. http://hdl.handle.net/2433/148648.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第10330号
エネ博第66号
新制||エネ||20(附属図書館)
UT51-2003-H751
京都大学大学院エネルギー科学研究科エネルギー応用科学専攻
(主査)教授 香山 晃, 教授 石井 隆次, 教授 落合 庄治郎
学位規則第4条第1項該当
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Rinkevich, A. B., M. I. Samoylovich, and A. F. Belyanin. "Effective Conductivity and Magnetic Permeability of Nanostructured Materials in Magnetic Field." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35340.
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The problem of homogenization the nanostructured materials placed in DC magnetic field has been discussed. The experimental data are obtained using metallic superlattices, metal-dielectric thin films and 3D-nanostructured materials. All these materials contain ferro- or ferrimagnetic component. The trans-mission and reflection coefficients were measured on the waves of millimeter waveband. It has been shown that the experimental frequency spectra of the coefficients in zero magnetic field can be described by the effective conductivity and dielectric permittivity. The spectra of ferromagnetic resonance, however, cannot be calculated correctly with the averaged magnetization.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35340
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Mackert, Marc. "Conductivity for schematic conversion : a new conceptualization for resistance to organizational change /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025637.
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Santiago, Claudia. "Resistivity and conductivity studies of the Rattlesnake Springs, New Mexico watershed." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Коваленко, Владислав Вячеславович. "Дослідження режимів мереж 35/10кВ операторів системи розподілу електроенергії." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/39563.
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В бакалаврській роботі на тему «Дослідження режимів мереж 35/10кВ операторів системи розподілу електроенергії » виділяються дві частини: перша – розрахункова (розділ1), де реалізуються загальні електроенергетичні задачі розрахунку та оптимізації режимів і визначення струмів короткого замикання для достатньо складних електричних мереж та друга – дослідницька (розділ 2), що присвячена аналізу режимів схем 35/10кВ Одесаобленерго.
Об`єктом дослідження є індивідуальна підстанція 110/35/10кВ, постачальна та розподільчі мережі 10/35кВ, та характерні проблемно-оріентовані експерементальні або промисловні моделі.
Предметом дослідження є невідомі режимні характеристики (напруги, втрати, регулюючі значення реактивної потужності, струми К.З. та інше), а також моделі матриць провідності і опору, методи рішення нелінійних електроенергетичних рівнянь та інше.
Мета роботи – підтвердити рівень інженерної кваліфікації бакалаврської роботи та згідно індивідуального завдання, виконати розробку розрахункової схеми Одесаобленерго і визначення головних характеристик (напруги, втрати потужності, споживання електроенергії) для режимних днів літнього та зимового максимуму.
Бакалаврська робота містить 67 сторінок, 29 рисунків, 7 таблиць, 4 креслення та 11 літературних посилань. Для реалізації завдання задіяно учбовий комп`ютерний комплекс L_APEZ, промислові електроенергентичні комплекси РАОТВ, Z_REGIM, OPTIM.QT. В процесі реалізації задач розроблені індивідуальні розрахункові схеми.In the bachelor's thesis on "Study of 35 / 10kV network modes of electricity distribution system operators" there are two parts: the first - calculation (section 1), which implements the general power problems of calculation and optimization of modes and short circuit currents for sufficiently complex electrical networks and the second - research (section 2), which is devoted to the analysis of the regimes of 35 / 10kV schemes of Odesaoblenergo. The object of studythere is an individual 110/35/10 kV substation, 110/35 kV supply and distribution networks, and typical problem-oriented experimental or industrial models. The subject of research there are unknown mode characteristics (voltages, losses, regulating values of reactive power, currents KZ, etc.), and also models of matrices of conductivity and resistance, methods of the decision of nonlinear electric equations and other. The goal of the work - to confirm the level of engineering qualification of the bachelor's degree and according to the individual task, to develop the calculation scheme of Odesaoblenergo and determine the main characteristics (voltage, power loss, electricity consumption) for the regime days of summer and winter maximum. The bachelor's thesis contains 67 pages, 29 drawings, 7 tables, 4 illustrations and 11 literary references. To implement the task, the educational computer complex L_APEZ, industrial power complexes RAOTV, Z_REGIM, OPTIM.QT are involved. In the process of realization of tasks individual calculation schemes are developed.
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Kalkundri, Kaustubh. "Development and verification of an apparatus for thermal resistance and thermal conductivity measurements." Diss., Online access via UMI:, 2006.
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Stephens, Clifford. "Analysis of the thermal conductivity of epoxy and reaction bonded silicon nitride matrix particulate composites." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11239.
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Russell, Carissa Don. "INTERFACIAL THERMAL CONDUCTIVITY USING MULTIWALL CARBON NANOTUBES." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/30.
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Shrinking volume, coupled with higher performance, microprocessors and integrated circuits have led to serious heat dissipation issues. In an effort to mitigate the excessive amounts of waste heat and ensure electronic survivability, heat sinks and spreaders are incorporated into heat generating device structures. This inevitability creates a thermal pathway through an interface. Thermal interfaces can possess serious thermal resistances for heat conduction. The introduction of a thermal interface material (TIM) can drastically increase the thermal performance of the component. Exceptional thermal properties of multiwall carbon nanotubes (MWCNTs) have spurred interest in their use as TIMs. MWCNTs inherently grow in vertically-oriented, high aspect ratio arrays, which is ideal in thermal interface applications because CNTs posses their superior thermal performance along their axis. In this paper, laser flash thermal characterization of sandwich‐bonded and cap‐screw‐bonded aluminum discs for both adhesive-infiltrated and “dry”, 100% MWCNT arrays, respectively. Thermal contact resistances as low as 18.1 mm2K/W were observed for adhesive‐infiltrated arrays and, even lower values, down to 10.583 mm2K/W were measured for “dry” MWCNT arrays. The improved thermal performance of the arrays compared to thermal adhesives and greases currently used in the electronics and aerospace industries, characterize MWCNT arrays as a novel, lighter‐weight, non‐corrosive replacement.
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Gatchalian, Dennis. "Characterization of aggregate resistance to degradation in stone matrix asphalt mixtures." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3342.
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Stone matrix asphalt (SMA) mixtures rely on stone-on-stone contacts among
particles to resist applied forces and permanent deformation. Aggregates in SMA should
resist degradation (fracture and abrasion) under high stresses at the contact points. This
study utilizes conventional techniques as well as advanced imaging techniques to
evaluate aggregate characteristics and their resistance to degradation. Aggregates from
different sources and types with various shape characteristics were used in this study.
The Micro-Deval test was used to measure aggregate resistance to abrasion. The
aggregate imaging system (AIMS) was then used to examine the changes in aggregate
characteristics caused by abrasion forces in the Micro-Deval.
The resistance of aggregates to degradation in SMA was evaluated through the
analysis of aggregate gradation before and after compaction using conventional
mechanical sieve analysis and nondestructive X-ray computed tomography (CT). The
findings of this study led to the development of an approach for the evaluation of
aggregate resistance to degradation in SMA. This approach measures aggregate
degradation in terms of abrasion, breakage, and loss of texture.
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Jamal, Ahmad. "Subjectivity and social resistance: a theoretical analysis of the Matrix Trilogy." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/7011.
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The Matrix (1999) is a science-fiction film that successfully bridges modern cinematic action sequences with philosophical parables. It recalls the tradition of philosophical elaboration through science-fiction narratives; a tradition that has existed since the time of Plato. This study aims to bridge the divide between philosophy and psychology by using a theoretical analysis to discuss and explore the ideas of social thinkers (featured in the Matrix Trilogy) and critically analyse them alongside established psychological theories. More specifically, this study provides an in-depth and critical exploration of the ways in which the philosophical works of Jean Baudrillard and Karl Marx, and the widely used and recognised psychological perspectives on human development, cognition and learning offered by both Urie Broffenbrenner and Jean Piaget to simultaneously elucidate a model of human subjectivity and development in today's techno- consumerist society with specific attention to critical resistance. This study suggests that with the rise of the internet and modern communication media; sociocultural and political issues that Broffenbrenner conceptualised as existing in the macrosystem, now have a presence in the microsystem, and correspond to Broffenbrenner's requirements as to what constitutes a proximal process. These processes, according to Broffenbrenner, have the most longstanding effects on our development and contribute the most to our personality. This study also argues that the pre-operational stage and the process of symbolisation both of which Piaget identified are important phases in the child's life that see the accrual and development of signs and discourses. These signs and discourses then contribute to the development of our mind's cognitive structures which Piaget called schema. These structures are developed as we grow and help us make sense of the world by processing information and organising our experiences. This would mean that we perceive and interpret our world through ideologically shaped mental structures. These findings stress the importance of ideological influences and their impact on development and hearken more closely towards ideas about the presence and the effects of ideology by thinkers like Plato and Marx, as well as the dystopian futures explored in science-fiction media like the Matrix Trilogy, George Orwell's 1984 (1948) and Aldous Huxley's A Brave New World (1932), and also the options for critical social resistance explored in the narratives and heroic deeds of these books and their characters.
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Imashuku, Susumu. "Electrical Conductivity of Grain Boundary in Accepter Doped Barium Zirconate." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/78014.
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Smith, Craig Edward. "Monitoring Damage Accumulation In SiC/SiC Ceramic Matrix Composites Using Electrical Resistance." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1249917100.
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Oddone, Valerio [Verfasser]. "Lightweight metal matrix composites with graphitic fillers showing high thermal conductivity and low thermal expansion. / Valerio Oddone." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1189139073/34.
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Martin, Jennifer M. "Quantification of the matrix hydraulic conductivity in the Santa Fe River Sink/Rise system with implications for the exchange of water between the matrix and conduits." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002882.
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Al-Fattani, Mohammed A. A. "Role of the biofilm matrix in resistance of Candida biofilms to antifungal agents." Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/4076/.
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The aim of this project was to investigate the possible role of the biofilm matrix as a barrier to drug diffusion in Candida biofilms and in mixed species fungal-bacterial biofilms. The penetration of antifungal agents through single- and mixed-species biofilms containing Candida was investigated using a novel filter disk bioassay. Fluconazole permeated all single-species Candida biofilms more rapidly than flucytosine. Drug penetration was more extensive with C. albicans than with the other species and the rates of diffusion of either drug through biofilms of three strains of C. albicans were similar. In all cases, after 3 to 6h the drug concentration at the distal edge of the biofilm was very high (many times the MIC). Nevertheless, drug penetration failed to produce complete killing of biofilm cells. These results indicate that poor antifungal penetration is not a major drug resistance mechanism for Candida biofilms under these conditions. It has been reported that the production of extracellular matrix by Candida biofilms growing under static incubation conditions is relatively minimal, but increases dramatically when developing biofilms are subjected to a liquid flow. In this study, Candida biofilms were grown under flow conditions in a modified Robbins device (MRD). Biofilms of C. albicans grown in the MRD produced more matrix material than those grown statically, and were significantly more resistant (P<0.001) to amphotericin B. Biofilms of C. tropicalis synthesized large amounts of matrix material even when grown statically, and such biofilms were completely resistant to both amphotericin B and fluconazole. Mixed-species biofilms of C. albicans and S. epidermidis RP62A, when grown statically or in the MRD, were also completely resistant to amphotericin B and fluconazole. Mixed-species biofilms of C. albicans and S. epidermidis M7, on the other hand, were completely drug resistant only when grown under flow conditions. Overall, these findings demonstrate that the matrix can make a significant contribution to drug resistance in Candida biofilms, especially under conditions similar to those found in catheter infections in vivo, and that the composition of the matrix material is an important determinant in resistance.
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Melo, Paola Mejia, Ramos Alexander Linares, Gary Duran Ramirez, and Jose Luis Cardenas Guillen. "Experimental evaluation of matrix suction and shear resistance of partially saturated sandy clay." Institute of Electrical and Electronics Engineers Inc, 2020. http://hdl.handle.net/10757/656563.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.At present, the construction of highways in Andean areas the connect the various most important towns and cities in South America has become has become a key element for its development, since these routes and viaducts allow free access to cover basic needs of education, work, food and health of the population. Much of the land in these areas is clay soils whose behavior is quite unpredictable because they present abrupt volume changes according to the variation of saturation in the soil. People who travel on roads on slopes of this type of soil are at high risk due to the slippage that the slopes suffer each year. The most recent was on April 3, 2020 because of the heavy rainfall that was registered in the area; there was a landslide that affected communication channels in the department of Cajamarca in Peru [1]. In this type of slopes landslides occur when the clayey soil is specifically saturated, because under these conditions the soil is not stable and loses cohesion between its particles, therefore it is important to make slope stability studies taking into account the partially saturated soil. This article presents results of tests allow to recognize the physical characteristics of the clay soil in the province of Chepén in Cajamarca. In addition, the filter paper method is used to elaborate the soil-water characteristic curve and a series of direct shear tests are carried cut at different degrees of saturation. With these results, the partially saturate soil fault surface is constructed that allows visualizing the value of the shear stress of the soil according to the saturation to which it is subjected. This value will be important for calculating the safety factor that the slope floor must have of the resistance shear of the soil according to the saturation, this value will be important for the calculation of the safety factor that the floor of the slope must have so that it does not fall. Therefore, considering this condition of the partially saturated soil in the slope stability analysis provides values of the safety factor that are closer to reality, without the need to carry out the analysis in the most critical condition, such as what it done in classical soil mechanics.
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Hart, Robert James. "Electrical resistance based damage modeling of multifunctional carbon fiber reinforced polymer matrix composites." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5493.
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In the current thesis, the 4-probe electrical resistance of carbon fiber-reinforced polymer (CFRP) composites is utilized as a metric for sensing low-velocity impact damage. A robust method has been developed for recovering the directionally dependent electrical resistivities using an experimental line-type 4-probe resistance method. Next, the concept of effective conducting thickness was uniquely applied in the development of a brand new point-type 4-probe method for applications with electrically anisotropic materials. An extensive experimental study was completed to characterize the 4-probe electrical resistance of CFRP specimens using both the traditional line-type and new point-type methods. Leveraging the concept of effective conducting thickness, a novel method was developed for building 4-probe electrical finite element (FE) models in COMSOL. The electrical models were validated against experimental resistance measurements and the FE models demonstrated predictive capabilities when applied to CFRP specimens with varying thickness and layup. These new models demonstrated a significant improvement in accuracy compared to previous literature and could provide a framework for future advancements in FE modeling of electrically anisotropic materials. FE models were then developed in ABAQUS for evaluating the influence of prescribed localized damage on the 4-probe resistance. Experimental data was compiled on the impact response of various CFRP laminates, and was used in the development of quasi- static FE models for predicting presence of impact-induced delamination.
The simulation-based delamination predictions were then integrated into the electrical FE models for the purpose of studying the influence of realistic damage patterns on electrical resistance. When the size of the delamination damage was moderate compared to the electrode spacing, the electrical resistance increased by less than 1% due to the delamination damage. However, for a specimen with large delamination extending beyond the electrode locations, the oblique resistance increased by 30%. This result suggests that for damage sensing applications, the spacing of electrodes relative to the size of the delamination is important. Finally CT image data was used to model 3-D void distributions and the electrical response of such specimens were compared to models with no voids. As the void content increased, the electrical resistance increased non-linearly. The relationship between void content and electrical resistance was attributed to a combination of three factors: (i) size and shape, (ii) orientation, and (iii) distribution of voids. As a whole, the current thesis provides a comprehensive framework for developing predictive, resistance-based damage sensing models for CFRP laminates of various layup and thickness.
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Pruitt, Freddie Lee III. "Chemoresistance of prostate cancer cells to docetaxel is modified by extracellular matrix substratum." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 92 p, 2008. http://proquest.umi.com/pqdweb?did=1459903001&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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GHOSH, DIPANKAR. "CRACK PROPAGATION AND FRACTURE RESISTANCE BEHAVIOR UNDER FATIGUE LOADING OF A CERAMIC MATRIX COMPOSITE." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1019491575.
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Bykov, P. A., T. A. Chernysheva, and L. I. Kobeleva. "Surface layers by wear tests of particulate metal matrix composites." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20526.
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The dry sliding wear behaviour of varying weight fraction of SiC particles reinforced AK12M2MgN aluminum alloy metal matrix composites (MMCs) fabricated by a vortex method was investigated using a pin-on-disk tester CETR UMT. The effect of
SiC particle content on the friction coefficient and wear resistance has been evaluated. The formation on friction surface of mechanical mixed layers consisting of debris and
fragmented SiC particles was indentified using a optical and a scanning electron microscopes.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20526
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Vallien, Ante. "Material characterization of multi-layered Zn-alloy coatings on fasteners : Effects on corrosion resistance, electrical conductivity and friction." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240956.
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Electroplated zinc-alloy coatings have been used on fasteners in the automotive industry for many years. The coating often consists of three layers: a zinc-alloy layer, a passivation layer and a sealer or top-coat. The coating layers affect the functional properties of the fastener (mainly the corrosion resistance, friction coefficient and electrical conductivity), and the aim of this thesis has been to increase the understanding of how these functional properties are affected by the properties of the coating. The corrosion resistance, friction coefficient and electrical conductivity of several different fasteners have been tested. Variations in these properties are connected with morphological and chemical properties of the electro-deposited zinc-alloy coating, passivation layer and sealer/top-coat of the fasteners. Measurement methods include scanning electron microscope and energy dispersive x-ray spectroscopy (SEM-EDX), light optical microscope (LOM), x-ray fluorescence (XRF), glow discharge optical emission spectroscopy (GD-OES), broad ion beam (BIB) and Fourier transform infrared spectroscopy (FTIR). From the results it can be concluded that the surface structure of zinc-nickel layers differs significantly from supplier to supplier. Screws with a thicker and rougher zinc-nickel surface structure displays higher friction values, but lower electrical resistance values. Optimisation of both of these properties is thus challenging. The distribution and surface structure of the outmost top-coat layer also differs between suppliers, but no connection between this and the functional properties of the screw has been found. The corners of the screw heads are often lacking a proper zinc-alloy coating, and this is also where corrosion is initiated. In general, the zinc-nickel alloy coating systems are performing better and display less corrosion spreading effects than the zinc-iron or pure zinc systems in terms of corrosion.Elektropläterade zinklegeringsbeläggningar har använts på fästelement inom bilindustrin under många år. Beläggningen består ofta av tre skikt: ett zinklegeringsskikt, ett passiveringsskikt och en ”top-coat”, eller ”sealer”. Beläggningsskikten påverkar fästelementens funktionella egenskaper (främst korrosionsbeständighet, friktionskoefficient och elektrisk ledningsförmåga) och syftet med denna avhandling har varit att öka förståelsen för hur dessa funktionella egenskaper påverkas av ytbeläggningens egenskaper. Korrosionsmotståndet, friktionskoefficienten och den elektriska ledningsförmågan hos flera olika fästelement har mätts. Variationer i dessa egenskaper kopplas till de morfologiska och kemiska egenskaperna hos den elektropläterade zinklegeringsskiktet, passiveringsskiktet och top-coat-skiktet hos fästelementen. Mätmetoder inkluderar svepelektronmikroskop och röntgenspektroskopi (SEMEDX), ljusoptiskt mikroskop (LOM), röntgenfluorescens (XRF), optisk strålningsspektroskopi (GD-OES), bred jonstråle (BIB) och Fourier-transformerad infraröd spektroskopi (FTIR). Av resultaten kan man dra slutsatsen att ytstrukturen hos zink-nickelskiktet skiljer sig avsevärt från leverantör till leverantör. Skruvar med tjockare och hårdare zink-nickelytstruktur visar högre friktionsvärden, men lägre elektriska resistansvärden. Optimering av båda dessa egenskaper är således utmanande. Distributionen och ytstrukturen hos det yttersta top-coat-skiktet skiljer sig också mellan leverantörer, men ingen samband mellan detta och skruvens funktionella egenskaper har hittats. Skruvhuvudets hörn saknar ofta en lämplig zinklegeringsbeläggning, och det är också där korrosion initieras. I allmänhet fungerar zink-nickellegeringsbeläggningssystemen bättre och visar mindre spridningseffekter i termer av korrosion än zinkjärn eller rena zinksystem.
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Xu, Degao. "Atomic Force Microscope Conductivity Measurements of Single Ferritin Molecules." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd645.pdf.
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Moxley, Charlotte L. "Heat resistance of Salmonella typhimurium and Listeria monocytogenes in suspension and in a biofilm matrix." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11012008-063019/.
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Perez, Garcia Ramon. "Increasing the Blast Resistance of Concrete Masonry Walls Using Fabric Reinforced Cementitious Matrix (FRCM) Composites." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42095.
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Unreinforced masonry (URM) walls are often used as load-bearing or infill walls in buildings in many countries. Such walls are also commonly found in existing and heritage buildings in Canada. URM walls are strong structural elements when subjected to axial loading, but are very vulnerable under out-of-plane loads. This type of loading may come from different sources , including seismic or blast events. When subjected to blast, wall elements experience large pressures on one of their faces due to the high pressure produced in the air when an explosion takes place. This wave of compressed air travels in a very short time and hits the wall causing immense stresses, which result in large shear and bending demands that may lead to wall failure, and the projection of debris at high velocities that can injure building occupants. This failure process is highly brittle due to the very low out-of-plane strength that characterize such walls.
In the past years, many investigations have been carried out to enhance the structural behaviour of unreinforced masonry walls under out-of-plane loading. Different strengthening methods have been studied, which include the use of polyurea coatings, the application of advanced fiber-reinforced polymer (FRP) composites or the use of concrete overlays in combination with high performance reinforcement. Fabric-reinforced cementitious matrix (FRCM) is a new composite material that overcomes some of the drawbacks of FRP. This composite material consists of applying coatings which consist of one or more layers of cement-based mortar reinforced with a corresponding open mesh of dry fibers (fabric). This material has been studied as a strengthening technique to improve in-plane and out-of-plane capacity of existing URM walls as well as other structural elements, mostly under seismic actions. This thesis presents an experimental and analytical study which investigates the effectiveness of using FRCM composites to improve the out-of-plane resistance of URM walls when subjected to blast loading.
As part of the experimental program, three large-scale URM masonry walls were constructed and strengthened with 1,2 and 3 layers of FRCM using unidirectional carbon fabrics. In all cases the specimens were built as load-bearing concrete masonry (CMU) walls. To increase shear resistance, two of the walls were also grouted with a flowable self-compacting concrete (SCC) mortar. Blast tests were conducted using the University of Ottawa Shock Tube and the results are compared with control walls tested in previous research at the University of Ottawa. The experimental results show that the FRCM retrofit significantly improved the blast performance of the URM load-bearing walls, allowing for increased blast capacity and improved control of displacements. The performance of the retrofit was found to be dependent on the number of retrofit layers.
As part of the analytical research, Single Degree of Freedom (SDOF) analysis was carried out to predict the blast behaviour of the strengthened walls. This was done by computing wall flexural strength using plane sectional analysis and developing idealized resistance curves for use in the SDOF analysis. In general, the analysis procedure is found to produce reasonably accurate results for both the resistance functions and wall mid-height displacements under blast loading.
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SETHI, VARUN. "Effect of Aging on Abrasive Wear Resistance of Silicon Carbide Particulate Reinforced Aluminum Matrix Composite." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1191951786.
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Bhatt, Hemanshu D. "Effect of interfacial thermal conductance and fiber orientation on the thermal diffusivity/conductivity of unidirectional fiber-reinforced ceramic matrix composites." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07282008-135034/.
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Raghavan, Vasudevan. "Effect of Interface, Density and Height of Carbon Nanotube Arrays on Their Thermal Conductivity: An Experimental Study." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289236348.
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Foster, Andrew. "Understanding, predicting and improving the performance of foam filled sandwich panels in large scale fire resistance tests." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/understanding-predicting-and-improving-the-performance-of-foam-filled-sandwich-panels-in-large-scale-fire-resistance-tests(3dc4bf07-82f0-4e3e-9cab-37e9244fe2a2).html.
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This thesis presents the results of research on sandwich panel construction, with the aims of developing tools for modelling sandwich panel fire performance and hence to use the tools to aid the development of sandwich panel construction with improved fire resistance. The research focuses on sandwich panels made of thin steel sheeting and a polyisocyanurate (PIR) foam core. For non-loadbearing sandwich panel construction, fire resistance is measured in terms of thermal insulation and integrity only. However, these two parameters are affected by mechanical performance of sandwich panel construction due to the high distortion and large deformation nature of sandwich panel construction under fire attack. Therefore, it is necessary to consider both thermal and mechanical performances of sandwich panels under fire conditions. The work in this thesis includes development of a thermal conductivity model for PIR foam as this thermal property is one of the key values in determining heat transfer through sandwich panels; this thermal conductivity model is based on the effective thermal conductivity of porous foams proposed by Glicksman (1994) and includes the effects of polymer decomposition and increases in foam cell size. It is validated against fire tests carried out on PIR sandwich panels 80mm and 100mm thick with steel facings of thickness 0.5mm. A large 3D sequentially coupled thermal-stress model of a full scale fire test has been developed in the commercial finite element analysis (FEA) software ABAQUS to provide insight into the way sandwich panels behave in a fire resistance test and also to assess different modelling techniques. Aspects and stages of the simulation that agree well with test data are explained. Limitations of the ABAQUS software for simulating sandwich panel fire tests are highlighted; namely, it is not possible to simulate the correct radiation heat transfer through panel joints, as cavity radiation cannot be specified in a fully coupled thermal-stress analysis. Joints are key components of sandwich panel construction. In order to obtain temperature development data for modelling joints, a number of fire tests have been carried out. These fire tests were conducted with different joint configurations and panel thicknesses under realistic fire conditions using timber cribs. The joint fire tests revealed significant ablation of the foam core within the joints of sandwich panels at high temperatures. At the beginning of fire exposure, the joint temperature on the unexposed surface was lower than that on the panel due to the better insulation property of air compared to the foam. However, as the joint gap increased due to ablation of the foam, the joint temperatures became higher than in the panel. A numerical simulation model has been created to investigate this behaviour. Using the aforementioned thermal model, numerical simulations have been carried out to examine the influences of possible changes to sandwich panel design on sandwich panel construction fire performance. It was suggested that if the maximum gap in the joints can be limited to 5mm, for example, by applying intumescent coating strips within the sandwich panel joints to counter the increasing gap formed due to core ablation, then the joint temperature on the unexposed surface would not exceed that of the panel surface, hence the joint would cease to be the weak link. To increase the panel fire resistance, the use of graphite particles in the PIR foam formulation may be considered to lower the contribution of radiative heat transfer within the foam cells by reducing the transmissivity of the cell walls. Graphite particles may offer considerable increases in the thermal resistance of PIR foam at high temperatures by limiting the radiation contribution which dominates heat transfer above 300oC.
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Elliot, Alexander James. "The evolution of the matrix genes of human influenza A and relationships to functional properties." Thesis, Open University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369075.
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Van, Laningham Gregg Thomas. "Oxidation resistance, thermal conductivity, and spectral emittance of fully dense zirconium diboride with silicon carbide and tantalum diboride additives." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43596.
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Zirconium diboride (ZrB₂) is a ceramic material possessing ultra-high melting temperatures. As such, this compound could be useful in the construction of thermal protection systems for aerospace applications. This work addresses a primary shortcoming of this material, namely its propensity to destructively oxidize at high temperatures, as well as secondary issues concerning its heat transport properties.To characterize and improve oxidation properties, thermogravimetric studies were per- formed using a specially constructed experimental setup. ZrB₂-SiC two-phase ceramic composites were isothermally oxidized for ∼90 min in flowing air in the range 1500-1900°C. Specimens with 30 mol% SiC formed distinctive reaction product layers which were highly protective; 28 mol% SiC - 6 mol% TaB₂ performed similarly. At higher temperatures, specimens containing lower amounts of SiC were shown to be non-protective, whereas specimens containing greater amounts of SiC produced unstable oxide layers due to gas evolution. Oxide coating thicknesses calculated from weight loss data were consistent with those measured from SEM micrographs.
In order to characterize one aspect of the materials' heat transport properties, the thermal diffusivities of ZrB₂-SiC composites were measured using the laser flash technique. These were converted to thermal conductivities using temperature dependent specific heat and density data; thermal conductivity decreased with increasing temperature over the range 25-2000°C. The composition with the highest SiC content showed the highest thermal conductivity at room temperature, but the lowest at temperatures in excess of ∼400°C, because of the greater temperature sensitivity of the thermal conductivity of the SiC phase, as compared to more electrically-conductive ZrB₂. Subsequent finite difference calculations were good predictors of multi-phase thermal conductvities for the compositions examined. The thermal conductivities of pure ZrB₂ as a function of temperature were back-calculated from the experimental results for the multi-phase materials, and literature thermal conductivities of the other two phases. This established a relatively constant thermal conductivity of 88-104 W/m·K over the evaluated temperature range.
Further heat transport characterization was performed using pre-oxidized, directly resistively heated ZrB₂-30 mol% SiC ribbon specimens under the observation of a spectral radiometer. The ribbons were heated and held at specific temperatures over the range 1100- 1330°C in flowing Ar, and normal spectral emittance values were recorded over the 1-6 μm range with a resolution of 10 nm. The normal spectral emittance was shown to decrease with loss of the borosilicate layer over the course of the data collection time periods. This change was measured and compensated for to produce traces showing the emittance of the oxidized composition rising from ∼0.7 to ∼0.9 over the range of wavelengths measured.
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Gordon, Neal A. "Material Health Monitoring of SIC/SIC Laminated Ceramic Matrix Composites With Acoustic Emission And Electrical Resistance." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1414835900.
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Mo, Jingwen. "Numerical and Experimental Study of Anisotropic Effective Thermal Conductivity of Particle Beds under Uniaxial Compression." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1288.
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Measurements of in situ planetary thermal conductivity are typically made using long needle-like probes inserted in a planet's surface, which measure effective thermal conductivity (ETC) in radial direction (parallel to surface). The desired vertical (perpendicular to surface) ETC is assumed to be the same as the horizontal. However, ETC of particle beds in vertical and horizontal directions is known to be an anisotropic property under low compressive pressures. This study further examines the anisotropy of bed ETC under low and high compressive pressures in both vacuum and air environments. The ratio of vertical to horizontal stress, K0, is measured for the particles used in these experiments. A resistance network heat transfer model has been developed in predicting the vertical and the horizontal ETC as a function of applied compressive pressure. The model predicts vertical ETC by using only macro-contact thermal resistances for both high and low applied compressive pressure regimes. It is proposed that the vertical and horizontal ETC of particle beds under uniaxial compression is related by compressive pressures in each direction. The horizontal compressive pressure, which is perpendicular to the applied compressive pressure, can be calculated with the use of at-rest pressure coefficient and subsequently used in macro-contact thermal resistance to predict the horizontal ETC. The vertical ETC is obtained using the same model by substituting vertical compressive pressure into macro-contact thermal resistance. A two-dimensional axisymmetric finite element model in the COMSOL Multiphysics software package has been developed to simulate heat transfer coupled with structural deformation of spheres under compressive pressures in a simple cubic (SC) packing arrangement. The numerical model is used as a tool to predict the lower limit of bed ETC as well as validating thermal contact resistance used in the theoretical model. The predictions from the numerical model can be extended to particle beds with different packing arrangements.
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May, Garrett. "A Periodic Technique for Measuring Thermal Properties of Thin Samples." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/603.
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We present a periodic technique for measuring the thermal conductivity and diffusivity of thin samples simultaneously. In samples of this type, temperature measurements must be made across the sample faces and are therefore subject to large error due to the interface resistance between the temperature sensor and the sample. The technique uses measurements of the amplitude and phase of the periodic temperature across both a reference sample and the unknown material at several different frequencies. Modeling of the heat flow in the sample allows the simultaneous determination of the thermal parameters of the sample as well as the interface resistance. Data will be presented for standard materials to show the viability of the technique.
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Lee, Yong-Joon. "Structure-property behavior of novel high performance thermoplastic and thermoset structural adhesives and composite matrix resins." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-162715/.
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Patankar, M. (Madhura). "Modeling and histopathological recognition of anoikis resistance in colorectal carcinoma." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526224404.
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Abstract Colorectal carcinoma (CRC) is an important cause of cancer-associated deaths. About 30–50% of CRCs show KRAS or BRAF mutation. In many cancers, anoikis, i.e. apoptosis induced by loss of extracellular matrix (ECM) contact, is disturbed. Anoikis resistance is essential for the formation of metastases, and since anoikis resistance assessment is based on in vitro cell cultures, the prognostic value of anoikis resistance is largely unknown. We aimed to identify the histopathological features indicating anoikis resistance in CRC and analyze their prognostic value. The roles of BRAF and KRAS mutations and survivin in anoikis resistance were analyzed and 3-D cell culture was used to model the histopathology of anoikis resistant (AR) structures. The two cohorts of CRC cases used in the study consisted of 62 (series 1) and 137 patients (series 2). Immunohistochemistry for ECM proteins enabled identification of tumor cells with and without ECM contact, and in both populations, apoptosis was determined with staining for caspase-cleaved keratin 18. Based on absence of ECM contact and decreased apoptosis rate, we identified micropapillary (MIP), cribriform and solid structures to represent the putative AR populations. High areal density of AR structures associated independently with short survival and was an independent prognostic factor. MIPs showed lower survivin expression, proliferation and apoptosis rates than non-MIP cells, and low apoptosis rate was associated with poor prognosis in stage I and II cases. For 3-D in vitro model of AR structures, we transfected Caco-2 cells with mutated KRAS or BRAF genes; both induced anoikis resistance as measured with Annexin V test in suspension culture. In 3-D cultures, native Caco-2 cells formed polarized cysts. In contrast, mutated cell lines formed partially filled cysts or solid structures, and inverted polarity in KRAS mutant cells. In conclusion, it is possible to identify putative AR structures by conventional histopathology and their number is associated with poor prognosis. MIPs represent a distinct subpopulation of CRC cells with features of quiescence. KRAS and BRAF mutations induce anoikis resistance in Caco-2 cells. In 3-D cultures, oncogenes KRAS and BRAF induce solid structures and cell piling, with structural resemblance to putative AR structures observed by histopathology. The mutated Caco-2 cells thus serve as a model to study the manifestation of anoikis resistance as a distinct histological feature with oncological significanceTiivistelmä Paksu- ja peräsuolisyöpä on yleinen syöpäkuoleman aiheuttaja. KRAS- tai BRAF-geenien mutaatio todetaan 30–50 prosentissa suolisyövistä. Anoikis tarkoittaa apoptoosia, jonka käynnistää solun irtoaminen soluväliaineesta. Anoikisresistenssi on etäpesäkkeen synnyn edellytys. Anoikisresistenssiä voidaan todeta vain soluviljelyssä, joten sen merkitystä syövässä in vivo ei ole aiemmin arvioitu. Tässä työssä pyrittiin tunnistamaan anoikisresistenssiin viittaavat muutokset histopatologisista suolisyöpänäytteistä ja selvittämään niiden vaikutusta potilaan ennusteeseen. Lisäksi tutkittiin BRAF- ja KRAS-mutaatioiden yhteyttä anoikisresistenssiin ja mallinnettiin anoikisresistenttejä (AR) rakenteita kolmiulotteisessa soluviljelmässä. Potilasaineisto koostui 199 suolisyöpäpotilaasta. Kudosleikkeistä värjättiin soluväliaineen komponentteja sekä määritettiin apoptoottiset ja jakautuvat solut (M30- ja Ki-67-värjäykset). AR-solupopulaatioiden tunnistamisessa käytettiin kriteereinä soluväliainekontaktin puuttumista ja vähentynyttä apoptoositiheyttä. AR-populaatioiksi osoittautuivat mikropapillaariset (MIP), seulamaiset ja solidit rakenteet. Näiden rakenteiden korkea kokonaisesiintyvyys osoittautui itsenäiseksi huonon ennusteen tekijäksi. MIP-rakenteissa surviviinin ilmentyminen ja apoptoosi- ja proliferaatiotiheys olivat vähentyneet muihin kasvainsoluihin verrattuna. Lisäksi apoptoottisten solujen pieni määrä MIP-rakenteissa liittyi huonoon ennusteeseen paikallisessa syövässä. Mallinnusta varten Caco-2 solut transfektoitiin mutatoiduilla KRAS- tai BRAF-geeneillä. Onkogeenien transfektion todettiin indusoivan anoikisresistenssiä. Kolmiulotteisessa soluviljelyssä polarisoituneet Caco-2 solut muodostivat säännöllisiä rauhasmaisia rakenteita. Onkogeeneillä transfektoidut solut muodostivat puolestaan osittain tai kokonaan täyttyneitä rakenteita ja KRAS-transfektio aiheutti solujen polariteetin kääntymistä. Havainnot osoittavat, että anoikisresistenssiä edustavat rakenteet voidaan tunnistaa kudosleikkeestä ja niiden runsas määrä viittaa huonoon ennusteeseen. MIP-rakenteissa todettiin lepotilan (quiescence) piirteitä. KRAS- ja BRAF-mutaatiot aiheuttavat Caco-2 soluissa anoikisresistenssiä. Kolmiulotteisissa soluviljelmissä onkogeenien vaikutus näkyy solujen pinoutumisena, mikä muistuttaa syöpäkudosnäytteissä todettuja AR-rakenteita. Tulosten perusteella modifioituja Caco-2 soluja voidaan hyödyntää anoikisresistenssin mallintamiseen ja tarkempien mekanismien tutkimiseen
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Jain, Shiwani. "Isotropically conductive adhesive filled with silver metalised polymer spheres." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/20297.
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Isotropic conductive adhesives (ICAs) have a growing range of applications in electronics packaging and have recently emerged as an important material in photo-voltaic module interconnections, particularly for thin-film and other non-silicon technologies where soldering processes are often unsuitable due to the nature of the metallisation or the limited maximum temperature the assembly can be exposed to. ICAs typically comprise of a high volume fraction of solid metallic flakes, usually silver, in an adhesive matrix because of its highly conductive oxide however, this thesis will focus on adhesives containing a large volume fraction of silver coated/metalised mono-sized polymer spheres (Ag-MPS). Incorporating silver coated mono-sized polymer spheres is anticipated to deliver specific advantages such as a significant reduction in the required silver content, improvement of the overall mechanical properties and flexibility to tune the properties of the filler according to the application compared with conventional flake filled adhesives. In this research advancements in the understanding of Ag-MPS filled ICAs, both through theory and experiments, have been made. Analytical models to predict an individual Ag-MPS resistance and Ag-MPS filled ICA resistance have been developed. The experiments based on the flat punch nanoindentation technique have been conducted to determine individual Ag-MPS resistances. The theoretical and experimental studies establish Ag-MPS diameter, coating resistivity, coating thickness, contact radius, and contact geometry as the main contributors towards the resistance of an Ag-MPS filled ICAs. These studies showed that Ag-MPS resistance decreases with increasing coating thickness and contact radius but increases with increasing coating resistivity. The experiments have also been conducted to investigate the effect of Ag-MPS volume fraction, diameter, coating thickness, curing conditions and shrinkage (affecting contact radius) on ICA conductivity and comparisons are made with flake filled and commercial ICAs. The results showed that ICA conductivity increases with increasing volume fraction and coating thickness but decreases with diameter. More importantly the results showed that conductivities similar to those of flake filled ICAs, including those commercially available, can be obtained using 70% less silver. The results show that, Ag content can be reduced further to just 7% with use of larger 30μm Ag-MPS but with a lower resulting conductivity. Thus for applications where very high conductivity is not required larger Ag-MPS may offer even greater potential cost benefits, which is something flake filled ICAs cannot offer. This is a significant achievement which can allow tuning of ICA formulations according to the demands of the application, which is not possible with the use of silver flakes as there is only a limited range of silver flake volume fractions that will yield useful levels of conductivity.
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Komori, Shogo. "Conductivity separation method into pore water and matrix components and its application to volcanic fields -New approach to evaluating mass flux of volcanic fluid." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142386.
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Taute, C. J. F. "Tumour specific targeted in vitro theranostics application of fabricated nanostructures in a multi-drug resistant ovarian carcinoma cell line." Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4530.
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Philosophiae Doctor - PhDOvarian cancer is called the “Silent Killer” as it is often diagnosed in advanced stages of the disease or misdiagnosed which ends with a poor prognostic outcome for the patient. A high rate of disease relapse, a high incidence-to-mortality ratio as well as acquired multidrug resistance makes it necessary to find alternative diagnostic- and therapeutic tools for ovarian cancer. Nanotechnology describes molecular devices with at least one dimension in the sub- 1μm scale and has been suggested as a possible solution for overcoming challenges in cancer multidrug resistance as well as early diagnosis of the disease. One-pot synthesized gold nanoparticles were used to demonstrate in vitro drug delivery of doxorubicin in a manner which overcame the cytoprotective mechanisms of a multidrug resistant ovarian carcinoma cell line (A2780cis) by inducing apoptosis mediated by caspase-3 within 3h of treatment. The gold nanoparticles were further functionalized with nitrilotriacetic acid and displayed specific interaction with a 6xHis-tagged cancer targeting peptide, chlorotoxin. Proprietary indium based quantum dots were functionalized with the same surface chemistry used for gold nanoparticles and bioconjugated with chlorotoxin. Wide field fluorescence studies showed the peptide-quantum dot construct specifically targeted enhanced green fluorescent tagged matrix metalloproteinase-2 transfected A2780cis cells in a specific manner. The cytoprotective multidrug resistant mechanisms of the ovarian carcinoma was overcome successfully with a single dose of doxorubicin loaded gold nanoparticles and tumour specific targeting was demonstrated using quantum dots with a similar surface chemistry used for the gold nanoparticles.
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Lemos, Georges [Verfasser], Florian [Gutachter] Pyczak, and Ulrich [Gutachter] Tetzlaff. "Development of Ni-based superalloy metal matrix composites, featuring high creep resistance / Georges Lemos ; Gutachter: Florian Pyczak, Ulrich Tetzlaff." Cottbus : BTU Cottbus - Senftenberg, 2021. http://d-nb.info/1227930690/34.
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Smith, Craig E. "Electrical Resistance Changes of Melt Infiltrated SiC/SiC Subject to Long-Term Tensile Loading at Elevated Temperatures." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461690076.
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Mansour, Rabih. "Mode I Interlaminar Fracture Properties of Oxide and Non-Oxide Ceramic Matrix Composites." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494248628194216.
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Mustapha, Lateef Abimbola, and Lateef Abimbola Mustapha. "Thermo-Mechanical Characterization and Interfacial Thermal Resistance Studies of Chemically Modified Carbon Nanotube Thermal Interface Material - Experimental and Mechanistic Approaches." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625379.
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Effective application of thermal interface materials (TIM) sandwiched between silicon and a heat spreader in a microelectronic package for improved heat dissipation is studied through thermal and mechanical characterization of high thermally conductive carbon nanotubes (CNTs) integrated into eutectic gallium indium liquid metal (LM) wetting matrix. Thermal conductivity data from Infrared microscopy tool reveals the dependence of experimental factors such as matrix types, TIM contacting interfaces, orientation of CNTs and wetting of CNTs in the matrix on the thermal behavior of TIM composite.
Observed generalized trend on LM-CNT TIM shows progressive decrease in effective thermal conductivity with increasing CNT volume fractions. Further thermal characterizations LM-CNT TIM however show over 2x increase in effective thermal conductivity over conventional polymer TIMs (i.e. TIM from silicone oil matrix) but fails to meet 10x improvement expected.
Poor wetting of CNT with LM matrix is hypothesized to hinder thermal improvement of LM-CNT TIM composite. Thus, wetting enhancement technique through electro-wetting and liquid crystal (LC) based matrix proposed to enhance CNT-CNT contact in LM-CNT TIM results in thermal conductivity improvement of 40 to 50% with introduction of voltage gradient of 2 to 24 volts on LM-CNT TIM sample with 0.1 to 1 percent CNT volume fractions over non voltage LM-CNT TIM test samples.
Key findings through this study show that voltage tests on LC- CNT TIM can cause increased CNT-CNT networks resulting in 5x increase in thermal conductivity over non voltage LC-CNT TIM and over 2x improvement over silicone-CNT TIMs. Validation of LM wetting of CNT hypothesis further shows that wetting and interface adhesion mechanisms are not the only factors required to improve thermal performance of LM-CNT TIM. Anisotropic characteristic of thermal conductivity of randomly dispersed CNTs is a major factor causing lower thermal performance of LM-CNTs TIM composite. Other factors resulting in LM-CNT TIM decreasing thermal conductivity with increasing CNT loading are (i) Lack of CNT-CNT network due to large difference in surface tension and mass density between CNTs and LM in TIM composite (ii) Structural stability of MWCNT and small MFP of phonons in ~5um MWCNTs compared to the system resulted in phonon scattering with reduced heat flow (iii) CNT percolation threshold limit not reached owing to thermal shielding due to CNT tube interfacial thermal resistance.
While mixture analytical models employed are able to predict thermal behaviors consistent with CNT-CNT network and CNT- polymer matrix contact phenomenon, these models are not equipped to predict thermo-chemical attributes of CNTs in LM-CNT TIM. Extent of LM-CNT wetting and LM-solid surface interfacial contact impacts on interfacial thermal resistance are investigated through LM contact angle, XPS/AES and SEM-EDX analyses on Au/Ni and Ni coated copper surfaces. Contact angle measurements in the range of 120o at both 55oC and 125oC show non wetting of LM on CNT, Au and Ni surfaces. Interface reactive wetting elemental composition of 21 days aged LM on Au/Ni and Ni surfaces reveals Ga dissolution in Au and Ni diffusion of ~0.32um in Au which are not present for similar analysis of 1 day LM on Au/Ni surface. Formation of Au-Ni-Ga IMC and IMC-oxide iono-covalency occurrence at the interface causes reduction in surface tension and reduction in interfacial contact resistance.
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Seidel, Gary Don. "Micromechanics modeling of the multifunctional nature of carbon nanotube-polymer nanocomposites." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1881.
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