Tesi sul tema "Grafting"
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1
Kulkarni, Nileema N. "Grafting". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ31599.pdf.
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2
Hu, Bizhen. "Improved Tomato Grafting Technologies". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480568784958911.
Testo completo
3
Wilson, Sarah Kate. "Durational painting : gifting, grafting, hosting, collaborating". Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18875/.
Testo completoAbstract (sommario):
This thesis takes as its focus contemporary painting, and develops an understanding of painting as a time-based medium. My research project addresses the array of strategies artists employ to produce durational paintings, a term I have coined as a means of referring to paintings that destabilise the traditional idea of painting as a static object, hung on a wall. The medium of painting embraces other mediums, such as performance and installation, to yield durational paintings. These paintings engage people in their production: vitally, they are participatory and are produced through collaboration. Furthermore, these paintings employ materials imbued with particular properties, such as longevity or, conversely, ephemerality. In time-based media collections and in existing histories of participatory and relational practices painting is absent: these omissions are redressed by the present study. Now that painting is time-based, it is ‘live’.
4
Herbert, Amy Angharad. "Bone grafting : tissue treatment and osseointegration". Thesis, Cardiff University, 2004. http://orca.cf.ac.uk/55547/.
Testo completoAbstract (sommario):
Bone grafts fill skeletal defects and provide a structure upon which new bone can be deposited. There is no standard method of storing bone prior to grafting, the three main storage regimes being stored fresh frozen at -80°C, gamma irradiated or freeze dried. The initial aim of this project was to determine how osteoblastic cells behaved when exposed to bone treated in the above ways. It was found that sterilisation of bone with gamma irradiation caused cell death in a number of the cells that came into contact with it. Therefore the use of gamma irradiation for grafting is contraindicated, a similar observation was observed for freeze-dried bone whereas cells grew and differentiated on fresh frozen tissue. The second aim of this study was to develop a system whereby bone marrow cells could be expanded in culture and retain their osteogenic potential so that they would be suitable for either coating a bone graft (thus increasing the rate of osseointegration of the graft) or used alone to treat small bone defects. Rodent bone marrow was used in a variety of cultures and bone formation was induced by either BGJ-b medium or ECCM (Endothelial cell conditioned medium). Control cultures were grown in alpha modification minimum essential medium. ECCM was overall found to produce a greater number of cells at the end of the incubation periods studied than BGJ-b medium. BGJ-b medium preferentially selected mineralization over cell proliferation under all of the culture conditions studied (monolayers, collagen gels and organ cultures). This medium would be best suited to forming small pieces of bone rapidly from bone marrow, to fill small bone defects such as those seen in the dental field. ECCM produced large numbers of osteogenic cells, which could potentially be used to coat large bone grafts.
5
Hunt, Paul Edward. "Protective colloids : understanding nucleation and grafting". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/protective-colloids-understanding-nucleation-and-grafting(a5f5c8c9-acc7-492b-bf81-3cf327af98cf).html.
Testo completoAbstract (sommario):
Alkali-soluble resins (ASRs) were prepared by (i) solution and (ii) emulsion polymerization. All ASRs were synthesized with number-average molar masses < 20,000 g mol-1 and all had 15 wt% methacrylic acid 5 wt% styrene, the remaining 80 wt% was composed of either methyl methacrylate or a combination of methyl methacrylate and ethyl acrylate. All emulsion ASRs were made to 20% solids, with volume-average particle diameters (dv) in the region 30 – 50 nm, with a glass transition temperature of 80 – 120 °C. Emulsion polymerization was the preferred route for ASR synthesis, to allow further studies on their dissolution behaviour. Before their use as colloidal stabilizers, the dissolution behaviour of the ASRs needed to beinvestigated e.g. effect of temperature, molar mass, and composition. Particle size and absorbance measurements were taken during dissolution of ASRs to achieve 100%neutralization and these were shown to have two stages, an apparent particle swelling (whichwas rapid), and a slower, decrease in particle size as water-soluble polymeric material wasdiffusing out of the ASR particles. From this, further interpretation allowed for calculating the diffusion coefficient of the ASR polymer using the Stokes-Einstein equation. Time-domain nuclear magnetic resonance (TD-NMR) was employed to enhance understanding of what is occurring in the ASR particles, and in the aqueous, continuous phase. The final aspect of this project was to use the ASRs prepared as colloidal stabilizers in emulsion polymerizations of butyl acrylate (BA) and butyl methacrylate (BMA) using varying levels and also the effect of adding additional surfactant. The results show that the effect of ASR molar mass, the concentration of stabilizer, and also the impact of the EA-containing ASR greatly influence stability, whereby lower ASR molar mass, higher levels of stabilizer and including EA greatly benefit colloidal stability in PBA latexes. In PBMA latexes, a similar trend was also observed, but, the presence of ethyl acrylate (EA) in the ASR backbone has a detrimental effect on the colloidal stability, caused by the inability of grafting to occur between the ASR and PBMA.
6
Mak, Siu Yan. "Mechanical factors influencing impaction bone grafting". Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486839.
Testo completoAbstract (sommario):
Impaction grafting for bone stock loss in revision total hip arthroI;>lasty has been used for over a decade. This technique typically involves the insertion of a cemented highly polished stem into impacted morsellised allograft bone. The aim is to compensate for the bone stock loss after failed primary hip arthroplasty and to provide a mechanical and biological scaffold for mechanical support and bone remodelling. The primary objective of this study is to quantify and optimise the graft properties so as to provide maximum supportive forces to the stem, and, at' the same time, to minimise the amount of per.:operative and post-operative femoral fractures. More than 60 parameters that could affect the mechanical properties of graft have been identified. Porcine bone from femoral heads was used in the study which was primarily divided into two parts: fundamental studies of the graft material, and in-vitro mechanical testing to replicate the clinical application of impaction bone grafting. Various techniques of graft preparation including defatting of the graft were investigated. A die-plunger was employed to perform uni-axial compressive testing on the graft at varying strain rates. It was found that defatted' graft demonstrated higher stiffness. Higher rates of loading resulted in increases in stiffness, hoop strain, axial force and Poisson's ratio. Preloading of the graft provided more predictable mechanical characteristics. Cyclic compressive testing showed th~t individual graft particles fractured during compression. In addition, it was found that the graft demonstrated increased viscoelastic properties at higher strain rates. In-vitro mechanical testing was also performed to compare the level of mechanical stability of a cemented polished stem with a larger uncemented polished stem. Composite femora were '' used for this comparison. It was found that the cemented stem showed higher mechanical stability in terms of the level of micromotion and migration, and uncemented stem failed in a catastrophic manner. The study provided information on how various factors contributed to the mechanical behaviour of bone graft and identified parameters that should be used when in-vitro testing of bone graft materials for use in impaction grafting.
7
Twitty, Anne. "The expression of tissue inhibitor of metalloproteinase during the early stages of bone graft healing". Thesis, Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21804023.
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8
Alladin, Tagenine. "Grafting and thermolysis of tetraneopentylzirconium on silica". Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26437.
Testo completoAbstract (sommario):
The gas-solid reaction of tetra(neopentyl)zirconium with the surface of Aerosil 200 pretreated thermally at 200°C has been investigated. Consistent with previous investigations of a similar reaction involving deposition of tetra(neopentyl)zirconium from solution, a unique supported organometallic fragment is formed. It was characterized by IR, 13C CP/MAS NMR, XAS and analytical techniques as (≡SiO)2Zr(CH2 C(CH3)3)2.
Thermolysis of silica-supported bis(neopentyl)zirconium(IV) at ca. 120°C results in the extrusion of one equiv. of neopentane. The nature of the remaining surface organometallic fragment was inferred, by its reactivity in olefin metathesis as well as by curve-fitting of its EXAFS spectrum, to be neopentylidenezirconium(IV), presumably formed by alpha-H abstraction. This result is analogous to previously established transformations of bis(alkyl) complexes of titanium, vanadium and chromium supported on silica, but was unexpected since earlier reports of the thermolysis of Zr(CH2C(CH3)3) 4 supported gamma-H abstraction and the formation of a zirconacyclobutane intermediate. The alpha-H abstraction occurs with pseudo-first-order kinetics and activation parameters DeltaH‡ = 24(5) kJ/mol and DeltaS ‡ = -19(7) J/K•mol.
Both the bis(neopentyl)- and neopentylidenezirconium(IV) fragments were found to catalyze polymerization of ethylene, at room temperature without any added cocatalyst. The reactions are pseudo-first-order in P(C2 H4).
9
Zheng, Betty Qilan. "Investigations of ethyl cellulose based grafting copolymers". Thesis, University of Auckland, 2003. http://hdl.handle.net/2292/2285.
Testo completoAbstract (sommario):
Copolymerisation of ethyl cellulose (EC) with methyl methacrylate (MMA) and vinyl acetate was carried out in solution, using a number of free radical initiators, to form graft copolymers with grafting yields up to 63% and weight average molecular weight about 9 x 104 g mol-1 Graft copolymerisation of MMA and EC appears to involve participation of comonomer charge transfer complexes at the initial stage of reaction, Interaction of EC with the carbonyl group of MMA enhances the electron-accepting ability of EC and promotes the formation of a donor-acceptor complex as matrix, with the resultant generation of a covalent bonded monomer radical, which then propagates in the usual manner to produce EC-g-PMMA. The influence of a number of experimental variables on the grafting efficiency of the EC-g-PMMA reaction, and the properties of the resulting copolymers, was investigated. The initiator has a significant effect on the grafting efficiency, which decreases in the order azobisisobutyronitril>ammonium persulphate>potassium persulphate>Ce(IV) ion. Benzoyl peroxide was found to be unsuitable because it promoted degradation of ethyl cellulose chains. The order of solvent influence on the grafting yield is chloroform>toluene>benzene. The grafting yield is also reaction time and temperature dependent. A2-3 hour reaction time and 40-50°C reaction temperature gives a substantial increase in both reaction rate and the molecular weight of the graft copolymer product. The introduction of PMMA graft side chains onto EC main chains leads to a significant decrease in the radius of gyration in solution, as determined by size exclusion chromatography, compared to linear EC. This finding is explained by the theory of Stockmayer and Fixman in terms of the number and type of long chain graft points in the molecule, Calculation of viscosity of EC-g-PMMA in solution using the Kurata equation gave values in good agreement with the experimentally determined viscosity. A significant result is that grafting PMMA branches onto EC reduces the hydrodynamic volume, and differential scanning calorimetry showed conclusively that increasing PMMA sidechain length reduces the chain flexibility, by reduction of free volume. The glass transition temperature of EC-g-PMMA, produced by using a large excess of MMA monomer and reasonably long reaction time, was shifted to higher temperature with increase of grafting yield and molecular weight. A single glass transition is observed for copolymers made using low initiator concentrations, and two glass transitions are found for higher initiator concentrations. In addition, EC-g-PMMA samples with higher grafting yield are more brittle than those with lower grafting yield. However, both the bending modulus (determined by dynamic mechanical thermal analysis) and elongation at break increase with grafting yield. Our experiments proved that the crystallinity of EC-g-PMMA is less than that of pure EC and greater than that of pure amorphous PMMA. The specific oxygen gas-permeability coefficients of EC-g-PMMA films decrease with increase of grafting yield. The reason is that grafting decreases of hydrodynamic volume. Interestingly, X-ray diffraction showed that the higher the grafting yields of EC-g-PMMA, the higher its crystallinity. Films of EC-blend-PMMA, made by solution casting and examined in cross section using scanning electron microscopy, showed an essentially multiple layer morphology with non-uniform dispersion of PMMA in the EC matrix. Scanning electron microscopy confirmed, as expected, that EC-g-PMMA cast films were homogeneous with no evidence of phase separation. The tensile strength of EC-g-PMMA films was typically about 20% higher than that of EC-blend-PMMA films, and the graft copolymer films exhibited greater oxygen permeability. A new model for graft copolymerisation to EC is proposed. The model provides for the possibility that grafting to EC with 48% ethoxy content can occur at the five OC2H5 groups and one OH group per unit. It was established using NMR spectrometry of EC-g-PMMA and EC-g-Poly (vinyl acetate) that under some conditions the ethoxy groups are the favoured graft sites. The liquid crystalline properties of EC and EC-g-PMMA were extensively investigated. Optical microscopy with crossed polarisers revealed that the relatively short mesomorphic temperature range of ethyl cellulose is extended downwards almost to ambient temperature in the graft copolymer. Low frequency Raman scattering showed that EC-g-PMMA has higher light scattering intensity than EC at ambient temperature. But it was lower than that of EC at 191°C. Moreover, the Jaynes-Cummings model cannot predict the light scattering intensity of EC-g-PMMA as a function of frequency very well, whereas the EIT-Kerr scheme is able to successfully account for the experimental observations. It was found that EC and EC-g-PMMA are pseudoplastic, lyotropic and thermotropic materials whose viscosity in solution is dependent on many factors, particularly on temperature and solution concentration. Both materials show unusual rheological behaviour, including maxima in the isothermal concentration dependence of viscosity. Unmodified EC exhibits thixotropic flow behaviour, whereas grafting PMMA side chains onto EC changes the flow behaviour to rheopectic, which is also typical of PMMA itself. As the temperature and concentration increase, the viscosity increases in response to the transition from an isotropic to an anisotropic state of EC-g-PMMA. Furthermore, experiments on the distinguishing characteristics of EC-g-PMMA indicate that different solvents affect its anisotropic flow behaviour to a greater or lesser extent. In particular, chloroform shows a stronger flow orientation effect than tetrachloroethane on EC-g-PMMA solutions. The rheological behaviour of EC and EC-g-PMMA in the nematic phase is much more complex than that of ordinary polymers or low molecular weight liquid crystals. The Doi theory is usually applicable to ordinary polymers or low molecular weight liquid crystals, but cannot predict shear stress as a function of shear rate; particularly at very low shear rates for EC and EC-g-PMMA. Whereas, the polydomain model is better to account for the observations. Measurements of thermally stimulated depolarisation current showed that EC-g-PMMA has a longer dipolar relaxation time in an electrical field. Molecular dipole motions of EC give a maximum depolarisation current at 138 °C in the glass transition region and another maximum near 200 °C, corresponding to dipolar relaxation in the liquid crystalline phase. EC-g-PMMA shows a broader dipolar relaxation temperature range in the liquid crystalline phase and the depolarisation current maximum shifts to a lower temperature. We have observed that field induced polarisation of EC-g-PMMA is affected by the length of the PMMA side chain, and obeys an interfacial model of the Maxwell-Wagner-Sillars type. It was confirmed by X-ray photoelectron spectroscopy that the length of the PMMA side chain could affect the surface properties. EC-g-PMMA has higher photoemission intensity than EC, and the photoemission intensity and depolarisation current increase with grafting yield.
10
Källrot, Martina. "Covalent vapor-phase grafting of degradable polymers /". Stockholm : Fiber- och polymerteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4544.
Testo completo
11
Dattani, Rupen. "Femoral impaction grafting : using bone graft substitutes". Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444261/.
Testo completoAbstract (sommario):
Background: Femoral impaction allografting to reconstitute bone loss during revision hip surgery has shown excellent results. However, limitations with the use of allografts have warranted research to investigate if bone graft substitutes could be a suitable alternative to replace or augment allograft in impaction grafting.;Aims and Methods: The objectives of this thesis were to assess if: The use of hydroxyapatite (HA) in various combinations with allograft will be biologically effective and functionally stable using a cemented impaction grafting technique in an ovine hemiarthroplasty model. The different treatment groups were compared by measuring the ground reaction forces and new bone formation. The addition of mesenchymal stem cells (MSCs) to allograft, HA or an allograft:HA mixture enhances the amount of new bone formation compared with impaction of the scaffold alone in an ovine metaphyseal femoral bone defect model. The architecture of the HA scaffold influences bone formation in an extra-skeletal sheep model.;Results: HA: allograft mixture of up to 90:10 demonstrated similar functional stability and amount of new bone formation as a 50:50 mixture. Addition of MSCs to allograft or a 50:50 allograft:HA mixture enhances the amount of new bone formation compared with unimpacted constructs. HA either alone or combined with MSCs induces bone growth only when constructed in block form and not in identical porous granular form.;Conclusion: HA is a suitable bone substitute to augment allograft and may be replace bone graft completely in impaction grafting of a femoral component. This has important clinical implications as HA is readily available, easy to use in surgery and not associated with the adverse effects encountered with allografts. The use of MSCs in the treatment of osteolysis holds great potential but further work is required to assess if this technology is transferable to humans.
12
Soliman, Ayman. "Variables affecting impaction grafting for hip revision". Thesis, Keele University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246873.
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13
Holden, Mark Alexander. "Studies on epidermal grafting in the Solanaceae". Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/10958.
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14
Papadopoulou, Kyriaki. "Neuropsychological sequalae of coronary artery bypass grafting". Thesis, University of East London, 2009. http://roar.uel.ac.uk/3735/.
Testo completoAbstract (sommario):
Objectives: To assess neurocognitive function after Coronary Artery Bypass Grafting (CABG); to compare and contrast pre- and post-operative test results and to characterise the degree of change in neurocognitive profiles. To identify neuropsychological patterns associated with different impairment models such as hypoxia and stroke. Methods: A comprehensive neuropsychological battery of tests was administered to a small number of individuals undergoing CABG at pre and post operative stage. In order to minimise practice effects, alternate tests were employed for memory, verbal and visuo-spatial functions. Mood measures were included. Results: There were six variables that indicated significant changes. These changes were in Processing Motor Speed, Verbal Executive function, Verbal, Visual learning and Memory, Verbal functions and Visuospatial functions. There was an overall improvement on mood after CABG. Conclusions: There were different neuropsychological sequelae - considering hypoxia and stroke impairment models - in the participants undergoing CABG via Cardiopulmonary Bypass (CPB). Neuropsychological deficits and improvements were identified.
15
Sommers, Marilyn Sawyer. "Circulatory response following coronary artery bypass grafting /". The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487683401444271.
Testo completo
16
Tork, Amir. "Novel liquid crystalline polymeric materials via ionic grafting". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ36331.pdf.
Testo completo
17
Raivio, Peter. "Role of thrombin in coronary artery bypass grafting". Helsinki University of Helsinki, 2007. http://urn.fi/URN:ISBN:978-952-10-4332-1.
Testo completo
18
Chen, Xiao Hua. "Patterning etch masks via the "Grafting-from polymerization". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/30768.
Testo completo
19
Hollands, Peter. "Differentiation and grafting of embryonic haemopoietic stem cells". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330219.
Testo completo
20
Sun, Zhonghua. "CT virtual intravascular endoscopy in aortic stent grafting". Thesis, University of Ulster, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248607.
Testo completo
21
Chirowodza, Helen. "Polymer-clay nanocomposites prepared by RAFT-supported grafting". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71914.
Testo completoAbstract (sommario):
Thesis (PhD)--Stellenbosch University, 2012.ENGLISH ABSTRACT: In materials chemistry, surface-initiated reversible deactivation radical polymerisation (SI-RDRP) has emerged as one of the most versatile routes to synthesising inorganic/organic hybrid materials consisting of well-defined polymers. The resultant materials often exhibit a remarkable improvement in bulk material properties even after the addition of very small amounts of inorganic modifiers like clay. A novel cationic reversible addition–fragmentation chain transfer (RAFT) agent with the dual purpose of modifying the surface of Laponite clay and controlling the polymerisation of monomer therefrom, was designed and synthesised. Its efficiency to control the polymerisation of styrene was evaluated and confirmed through investigating the molar mass evolution and chain-end functionality. The surface of Laponite clay was modified with the cationic chain transfer agent (CTA) via ion exchange and polymerisation performed in the presence of a free non-functionalised CTA. The addition of the non-functionalised CTA gave an evenly distributed CTA concentration and allowed the simultaneous growth of surface-attached and free polystyrene (PS). Further analysis of the free and grafted PS using analytical techniques developed and published during the course of this study, indicated that the free and grafted PS chains were undergoing different polymerisation mechanisms. For the second monomer system investigated n-butyl acrylate, it was apparent that the molar mass targeted and the monomer conversions attained had a significant influence on the simultaneous growth of the free and grafted polymer chains. Additional analysis of the grafted polymer chains indicated that secondary reactions dominated in the polymerisation of the surface-attached polymer chains. A new approach to separating the inorganic/organic hybrid materials into their various components using asymmetrical flow field-flow fractionation (AF4) was described. The results obtained not only gave an indication of the success of the in situ polymerisation reaction, but also provided information on the morphology of the material. Thermogravimetric analysis (TGA) was carried out on the polymer-clay nanocomposite samples. The results showed that by adding as little as 3 wt-% of clay to the polymer matrix, there was a remarkable improvement in the thermal stability.
AFRIKAANSE OPSOMMING: Oppervlakgeïnisieerde omkeerbare deaktiveringsradikaalpolimerisasie (SI-RDRP) is een van die veelsydigste roetes om anorganiese/organiese hibriedmateriale (wat bestaan uit goed-gedefinieerde polimere) te sintetiseer. Die produk toon dikwels ʼn merkwaardige verbetering in die makroskopiese eienskappe – selfs na die toevoeging van klein hoeveelhede anorganiese modifiseerders soos klei. ʼn Nuwe kationiese omkeerbare addisie-fragmentasie kettingoordrag (RAFT) middel met die tweeledige doel om die modifisering van die oppervlak van Laponite klei en die beheer van die polimerisasie van die monomeer daarvan, is ontwerp en gesintetiseer. Die klei se doeltreffendheid om die polimerisasie van stireen te beheer is geëvalueer en bevestig deur die molêre massa en die funksionele groepe aan die einde van die ketting te ondersoek. Die oppervlak van Laponite klei is gemodifiseer met die kationiese kettingoordragmiddel (CTA) deur middel van ioonuitruiling en polimerisasie wat uitgevoer word in die teenwoordigheid van ʼn vrye nie-gefunksionaliseerde CTA. Die toevoeging van die nie-gefunksionaliseerde CTA het ʼn eweredig-verspreide konsentrasie CTA teweeggebring en die gelyktydige groei van oppervlak-gebonde en vry polistireen (PS) toegelaat. Verdere ontleding van die vrye- en geënte PS met behulp van analitiese tegnieke wat ontwikkel en gepubliseer is gedurende die verloop van hierdie studie, het aangedui dat die vry- en geënte PS-kettings verskillende polimerisasiemeganismes ondergaan. n-Butielakrilaat is in die tweede monomeer-stelsel ondersoek en dit was duidelik dat die molêre massa wat geteiken is en die geënte polimeerkettings. ʼn Nuwe benadering tot die skeiding van die anorganiese/organiese hibriedmateriale in hulle onderskeie komponente met behulp van asimmetriese vloeiveld-vloei fraksionering (AF4) is beskryf. Die resultate wat verkry is, het nie net 'n aanduiding gegee van die sukses van die in-situ polimerisasiereaksie nie, maar het ook inligting verskaf oor die morfologie van die materiaal. Termogravimetriese analise (TGA) is uitgevoer op die polimeer-klei nanosaamgestelde monsters. Die resultate het getoon dat daar 'n merkwaardige verbetering in die termiese stabiliteit was na die toevoeging van so min as 3 wt% klei by die polimeermatriks.
22
Phipps, Kirsty. "The engineering and biology of femoral impaction grafting". Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1445787/.
Testo completoAbstract (sommario):
Femoral impaction grafting is a technique where bone graft is impacted into the femur prior to cementing a stem in place. The technique is designed to compensate for bone stock loss in revision surgery, however it has associated problems of implant movement / subsidence and periprosthetic fractures. The hypothesis for this thesis was that the stability and remodelling of impaction grafting could be improved, either by changing the graft size or by adding a synthetic graft. To quantify the technique of impaction grafting the Exeter slap hammer was modified, enabling force readings to be measured in nine surgical cases with four different surgeons. The results found that the average force that travels through the impactor is 1.8 to 8.4 kN, which is equivalent to three to eleven times body weight. These readings were used in the subsequent studies to replicate the current technique. It was hypothesised that varying the graft size might alter the porosity, strength and remodelling of impacted graft. Three graft groups were studied Small, Large and a Graded mix. The results found that the impacted Large graft had higher porosity and lower axial stiffness than the Small and Graded Graft. A noted reduction in graft density was found after six weeks in-vivo compared with twelve, irrespective of graft type. Since density can be related to mechanical strength this led to the question: Could the inclusion of a synthetic bone graft improve the mechanical properties of remodelling graft A 50:50 mix of allograft and BoneSave was compared with allograft. No difference in stiffness was found between the groups after six and twelve weeks remodelling. These studies were carried out using small test samples either in the laboratory or in- vivo. In order to determine if synthetic graft extenders could be used clinically tests in more realistic models were undertaken. Mechanical analysis was conducted on the 50 % inclusion of two graft extenders with allograft, namely: BoneSave and Appapore-60. The results of both projects showed a positive result.
23
Zilic, Elvis. "Radiation curing and grafting of charge transfer complexes". Thesis, View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/19385.
Testo completoAbstract (sommario):
Charge transfer (CT) complexes have been used in a number of radiation polymerisation processes including grafting and curing. The complexes studied include donor (D) monomers like vinyl ethers and vinyl acetate (VA) with acceptor (A) monomers such as maleic anhydride (MA). Both UV and EB have been utilised as radiation sources. The complexes are directly grafted to these substrates in the presence of radiation. The complexes yield novel copolymers when radiation cured with concurrent grafting improving the properties of the finished product. The term cure grafting has been proposed for this concurrent grafting process. Studies in basic photografting work to complement the cure grafting have been proposed. The role of solvent in grafting is discussed, particularly the effect of aromatics in photografting to naturally occurring trunk polymers like wool and cellulose. The effect of the double bond molar ratio (DBMR) of the DA components in grafting is examined. The ultraviolet (UV) conditions for gel formation during photografting, hence the importance of homopolymer yields in these processes is reported. A plausible mechanism to explain the results from this photografting work is proposed. The significance of these photografting studies in the related field of curing, especially in UV and ionising radiation (EB) systems, is discussed. EB curing and cure grafting of charge transfer (CT) monomer complexes is investigated. The EB results are compared with UV curing and cure grafting of the same complexes. The work has been extended to include EB/UV curing and cure grafting of thiolene systems. The significance of these results in the potential commercial application of these complexes is discussed. Variables affecting the UV/EB curing and cure grafting of thiolenes on cellulose have been studied. These include effect of varying the type of olefin, increasing the functionality of the thiol, use of acrylate monomers and oligomers in hybrid systems, altering the surface structure of the cellulose and finally the role of air in these processes particularly with EB. Photopolymerisation of the thiol-enes in bulk has also been investigated. The thesis content is based on the published work of 14 research papers over the course of the project.
24
Zilic, Elvis. "Radiation curing and grafting of charge transfer complexes". View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/19385.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--University of Western Sydney, 2008.Thesis submitted to the University of Western Sydney, College of Health and Science, School of Natural Sciences, in fulfilment of the requirements for admission to the Doctor of Philosophy. Includes bibliography.
25
Ofoegbu, Chimu K. P. "Outcomes of "off-pump" coronary artery bypass grafting in a developing country : advantages over coronary artery bypass grafting on cardiopulmonary bypass". Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11432.
Testo completoAbstract (sommario):
Includes abstract.Includes bibliographic references (leaves 53-62).
Off-pump coronary artery bypass grafting (OPCAB) was developed to avoid the deleterious effects of CPB. Current literature reveals some peri-operative advantages of OPCAB, with few studies detailing these in Africa. We review our institutional experience with both approaches in higher risk patients to determine pre-operative characteristics, short and mid-term outcomes in a developing country.
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Lie, Ken Jie Ronny Ket Phoei. "The healing of composite endochondral bone grafts a qualitative and quantitative analysis /". Hong Kong : Faculty of Dentistry, The University of Hong Kong, 1995. http://sunzi.lib.hku.hk/HKUTO/record/B38628120.
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李國培 e Ken Jie Ronny Ket Phoei Lie. "The healing of composite endochondral bone grafts: a qualitative and quantitative analysis". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B38628120.
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Houbenov, Nikolay. "Adsorption and Grafting of Polyelectrolytes at Solid-Liquid Interfaces". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1125936797959-47973.
Testo completoAbstract (sommario):
A novel strategy for fabrication of responsive functional polymer films is based on grafting of several different functional polymers onto a solid substrate at high grafting density, resulting in varied types of polymer brushes. Such an arrangement suggests many interesting applications of the multicomponent polymer brushes, regarding their versatile adaptive surfaces, capable for responding to changes of solvent polarity, pH, temperature, electromagnetic field and other stimuli, generally by reversible swelling. Mixed amphiphilic polystyrene-poly(2-vynil pyridine) (PS-P2VP) brushes are an example for responsive class of smart materials, which can switch between hydrophilic and hydrophobic energetic state upon changes in the quality of surrounding media. The switching of wettability was found to operate in a broad range and was selectively controlled in organic solvents and in aqueous solutions. Another example for an adaptive/switching behavior is addressed to a polymer brush with a remarkable response to the pH and the ionic strength variations of the aqueous solutions. Combination of weak polyacrylic acid, PAA, and weak polybase, P2VP, in the anchored layer allowed one with a small shift of the pH, to obtain a significant effect on the surface and the interfacial properties of the material. Both type of polymer brushes were examined as adsorbing materials for nanoparticles and charged synthetic- and bio-macromolecules. Their adaptive properties were successively linked to the results of the adsorption experiments. The simplest case was adsorption of nano-particles, functionalised with strong ionic groups, onto binary, PAA-P2VP, polyelectrolyte brushes. Maintaining a constant charge density of the adsorbing component (strong polyelectrolyte effect), allowed one to cause and manipulate a privileged swelling of one of the weak polyelectrolyte brush layers, without affecting the adsorbate properties, and to regulate the thickness of adsorbed layer only by the pH signal. In the case of adsorption of macromolecules with tuneable electrical charge (polyampholytes and proteins), the system became more complicated, regarding their environmentally responsive properties, similar to that exhibited by the polymer brushes. The driving forces were regulated by the switching performance of the brush, simply by adjusting the pH and/or ionic strength conditions. The adsorbed amount and morphological changes of polyampholyte layers were investigated as function of pH and was performed on mixed amphiphilic and binary polyelectrolyte brushes. A special emphasis was set on the binary brush capability to take the control over the interfacial performance of attaching proteins. It was found, that the sharp environmental response of the adsorbent (the polymer brush) strongly influences the morphology of adsorbed protein layers, their thickness and properties. Changing the polarity of the substrate allowed one to regulate the adsorption processes qualitatively and quantitatively. The significant aggregation of protein molecules on PS-P2VP brush and their disassembly on PAA-P2VP brush at the same solvent conditions, we devote to the hydrophobic-hydrophilic transition, occurred at the surface by replacing PS with PAA. The protein aggregates, monitored on the surface of PS-P2VP, sufficiently decrease their size, when switching the brush energetic state from hydrophobic to hydrophilic by adjusting the pH of the media. This effect was found to be well controlled by the brush switching phenomenon in hydrophilic-hydrophobic direction and vice versa. In conclusion, we showed how the structural reorganization in thin polymer brush layers of different type may dramatically affect their surface properties. The adaptive behavior in response of external stimuli was found to be a basis for highly specific interactions, depending on geometric factors, conformational state and environment.
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Marais, Andrew. "Xyloglucan modification using controlled polymer grafting for biocomposite applications". Thesis, KTH, Centrum för Biofibermaterial, BiMaC, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90872.
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Hanipah, Suhaiza Hanim. "A process for melt grafting itaconic anhydride onto polyethylene". The University of Waikato, 2008. http://hdl.handle.net/10289/2462.
Testo completoAbstract (sommario):
Currently, extensive research in using bio‐derived polymers is being done, highlighting the importance of sustainable, green polymeric materials. Some sustainable alternatives to synthetic polymers include lignin, starch, cellulose or blends of these with petroleum‐based polymers. In New Zealand, large quantities of animal derived proteins are available at very low cost, making it ideal as a sustainable alternative to petroleum‐derived polymers. However, the processability of most proteins is very difficult, but can be improved by blending with synthetic polymers, such as polyolefins. To improve, the compatibility between these substances, a functional monomer could be grafted onto the polyolefin chain. Using an appropriate functional group, the polyolefin could then react with certain amino acids residues in the protein. Lysine and cystein are the two most appropriate amino acid residues because of their reactivity and stability at a wide pH range. In this study, free radical grafting of itaconic anhydride (IA) onto polyethylene was investigated. IA was selected because it is capable of reacting with polyethylene and amino acid residues, such as lysine. The objective of the research was to identify and investigate the effect of reaction parameters on grafting. These were: residence time, temperature, initial monomer concentration as well as peroxide concentration and type. Grafting was characterized in terms of the degree of grafting (DOG), percentage reacted and the extent of side reactions. The reaction temperature was taken above the melting point of the polyethylene, monomer and decomposition temperature of the initiator. It was found that above 160 C polymer degradation occurred, evident from sample discolouration. A higher degree of grafting can be achieved by increasing the initial monomer concentration up to a limiting concentration. The highest DOG achieved was about 1.2 mol IA per mol PE, using 2 wt% DCP. When using 2 wt % peroxide, the limiting concentration was found to be 6 wt% IA, above which no improvement in DOG was achieved. It was found that DCP is much more effective at grafting, compared to DTBP because DTBP is more prone to lead to side reactions than DCP. iv It was found that a residence time of 168 seconds resulted in the highest DOG, corresponding to 4 extrusions in series. However, it was also found that an increase in residence time resulted in an increase in polymer degradation. The tensile strength of PE decreased after two extrusions when using DTBP, and three extrusions, when using DCP. Young's modulus decreased only slightly, while all samples showed a dramatic decrease in ductility, even after one extrusion. It was concluded that degradation had a more pronounced effect on mechanical properties than cross‐linking, and residence time should therefore not exceed three extrusions in series, which corresponded to about 126 seconds. It can be concluded that a high reaction temperature and high initiator concentration lead to a low degree of grafting, accompanied by high cross‐linking and increased degradation. On the other hand, high monomer concentration and high residence time lead to a high degree of grafting. Optimising grafting is therefore a trade off between maximal DOG and minimising side reactions such as cross‐linking and degradation and optimal conditions do not necessarily correspond to a maximum DOG. Other factors, such as the use of additives to prevent degradation should also be investigated and may lead to different optimum conditions.
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Lockowandt, Ulf. "Endothelial function and dysfunction in coronary artery bypass grafting /". Stockholm : [Karolinska institutets bibl.], 2002. http://diss.kib.ki.se/2002/91-7349-111-x/.
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Ohrlander, Mattias. "Modification of stable and degradable polymers by heterogeneous grafting /". Stockholm, 1998. http://www.lib.kth.se/abs98/ohrl0602.pdf.
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Österberg, Klas. "Vascular wall responses to bypass grafting : studies in mice /". Göteborg : Dept. of Molecular and Clinical Medicine, Vascular Surgery, Institute of Medicine, Sahlgrenska Academy at Göteborg University, 2008. http://hdl.handle.net/2077/9437.
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Nelson, Jennifer A. "Fluorescence microscopy analysis of surface grafting on polymeric fibers". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/8648.
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Kibaris, Anna-Maria. "Mary Shelley's monstrous patchwork : textual "grafting" and the novel". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23337.
Testo completoAbstract (sommario):
This thesis examines selected prose fiction works of Mary Wollstonecraft Shelley in an effort to establish a clearer understanding of the creative principles informing her writing, based on more evidence than her well-known novel Frankenstein provides. Overturning the hitherto dismissive and/or reductive critiques of her lesser-known works, this thesis challenges negative assessments by reinterpreting the structure of Shelley's fiction. Concentrating particularly on the early Frankenstein(1818), Mathilda (written in 1819), and The Last Man (1826), with a focus on the use of insistent embedded quotations, this thesis begins by exploring Shelley's belief in textuality as a form of "grafting." As scholars have suggested, Shelley's literary borrowings are a result of her materialist-based views of human reality. The persistent use of embedded quotations is one way in which Shelley's fiction represents texts as collations of materials. The core of the argument posits that citational "grafting" has distinctive and striking effects in each of the works examined. In Frankenstein, quotations underscore existential alienation by pointing to the need for texts to fill in the lacunae of human understanding; in Mathilda, the narrator uses citations to create a sense of personal identity; and in The Last Man, citational excerpts are used with the assumption that they are shared pockets of meaning belonging to a community of human readers. This reconceptualization of Shelley's writing contributes to the generic taxonomies that are now being used to retheorize "the novel" in more inclusive and specific ways.
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Gray, Ian. "Grafting of acrylic monomers to hydrowyethyicellulose during emulsion polymerisation". Thesis, University of Manchester, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506453.
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Dunckley, Maria. "Barriers to recovery after coronary artery bypass grafting surgery". Thesis, Coventry University, 2007. http://curve.coventry.ac.uk/open/items/cb90ef80-269b-6eb1-2986-bb2c61227bb3/1.
Testo completoAbstract (sommario):
Introduction: Coronary artery bypass grafting surgery is an effective treatment for coronary heart disease for many patients; however, evidence suggests that there are some patients who do not report a good post-operative recovery. Although several studies have begun investigating possible reasons for these observations, little is known about the impact of CABG on quality of life and there still remains a lack of information that can help clinicians identify those people more likely to experience poorer recovery so that interventions can be targeted appropriately. Aims: The overall aim was to investigate barriers to and facilitators of recovery after CABG. Method: Phase 1 was a retrospective qualitative study involving semi-structured interviews with eleven patients who had undergone CABG and with ten health professionals experienced in caring for these patients. Data were analysed using thematic analysis. Phase 2 was a prospective study comprising two components, questionnaire and interview. The questionnaire included measures of quality of life, perceived recovery, demographic and psychosocial variables and was administered prior to surgery and at six and twelve months post-surgery. A sample of ten people who completed questionnaires were interviewed at the same time points and data analysed using framework analysis. Results: Interview data described the patient experience of undergoing CABG and identified components of a good recovery from the patient perspective. Patient and health professional participants identified numerous barriers and facilitators to recovery at three key time points - prior to surgery, during the hospital inpatient stay and post-CABG - and noted the complex inter-relationships between them, thus emphasising the need for a holistic approach to investigating recovery. Questionnaire data described the pattern of psychosocial functioning, quality of life and perceived recovery across the surgical pathway and identified depression and self-efficacy as the main predictors of post-CABG quality of life and perceived recovery. Using interview and questionnaire data a model of recovery is proposed. Conclusions: Findings from this research have identified a complex inter-related network of barriers and facilitators to recovery, suggested the possible mechanisms by which they impact on post-CABG outcome and identified recommendations for clinical practice.
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Eshtiagi, Zahra. "Rejuvenation of walnut (Juglans regia L.) by sequential grafting". Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394423.
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Mirdamadian, Pegah, e Nargi Raha Salahshour. "Grafting materials for alveolar cleft reconstruction -a systematic review". Thesis, Malmö universitet, Odontologiska fakulteten (OD), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42795.
Testo completoAbstract (sommario):
Aim: The aim of this literature study was to systematically review the scientific evidence on the most effective donor sites and/or bone substitute material for secondary alveolar cleft grafting in alveolar cleft patients. Material and method: In order to acquire a systematic and transparent reporting this literature review was conducted according to the PRISMA statement. The literature search was performed in the following four databases; PubMed, CENTRAL, Web of Science and Scopus.The quality of the included studies was assessed using the revised Cochrane Risk of Bias 2 tool (RoB 2 tool). Result: The search identified 4754 studies. Five RCT studies was included in this systematic review and assessed different donor site or bone substitute materials. Two studies showed low risk of bias and three moderate risk of bias. Only one study showed a statistically significant difference when comparing iliac bone to substitute material however all studies presented substitute materials with satisfactory results. Conclusion: According to the data from this systematic review no clear conclusion can be drawn regarding what the most effective bone donor site and/or tissue engineered bone substitute material to use in secondary bone grafts. Based on the available evidence iliac bone could still be regarded as a benchmark, but more research and RCT’s of high quality are required, especially for artificial bone substitute materials.Syfte: Syftet med denna litteraturstudie var att systematiskt granska den vetenskapliga evidensen gällande det mest effektiva bentagningsstället och/eller bensubstitutmaterialet vid sekundär bentransplantation hos patienter med käkspalt. Material och metod: För att uppnå en systematisk och transparent rapportering av denna litteraturstudie följdes PRISMA statement. Litteratursökningen gjordes i följande fyra databaser; PubMed, CENTRAL, Web of Science och Scopus. Kvaliteten av inkluderade studier granskades med hjälp av Cochrane Risk of Bias 2 tool (Rob 2 tool). Resultat: Sökningen identifierade 4754 studier. Fem RCT studier inkluderades i denna systematiska översikt vilka värderade olika bentagningsställen eller bensubstitut. Två studier bedömdes ha låg risk för bias och tre artiklar måttlig risk för bias. Endast en studie visade på en statistiskt signifikant skillnad vid jämförelse av höftben med bensubstitut däremot presenterade samtliga studier substitutmaterial med tillfredsställande resultat. Konklusion: Denna systematiska översikt visade att ingen klar slutsats kan dras gällande vilken det mest effektiva bentagningsstället eller bensubstitutsmaterialet är för sekundär bentransplantation hos patienter med käkspalt. Baserat på tillgänglig evidens kan transplantat från höftbenet fortfarande anses vara bäst lämpat men mer forskning samt RCT studier av hög kvalité erfordras, särskilt för artificiella bensubstitutmaterial.
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Alam, Nawsheen. "The cellular biology of tendon grafting and graft integration". Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/the-cellular-biology-of-tendon-grafting-and-graft-integration(ae75cfd2-86f4-4d5d-9511-edca52d2a6f6).html.
Testo completoAbstract (sommario):
Background: Prolonged recovery after tendon injury has given rise to the need for innovative therapy including tendon engineering and cell based therapies. The role of cells in grafted or engineered tendon is poorly understood. Clarifying the persistence of grafted tissue is fundamentally important to ensure that tissue engineering strategies are fit for clinical application. We have devised a murine model for tendon grafting that allows for cell tracking and the assessment of tendon integration and engineered construct integration. Materials and methods: We studied the macroscopic and microscopic architecture of the mouse Achilles tendon to investigate its properties as a study model. Using microsurgical techniques, transgenic tendon grafting procedures were then carried out between C57B/L6 wild type and GFP (Green Fluorescent Protein) mice Achilles tendon. The temporal and spatial fate of the cells in the graft was assessed using quantitative serial histology and immunohistochemistry with Three Dimensional reconstruction. Markers for proliferation, collagen synthesis, cell death and inflammatory infiltrate were used. The Achilles tendon model was also applied to test its applicability to investigate tissue engineered tendon constructs developed in vitro. Results: GFP positive graft cells were seen at Day 3 and Day 21 but disappeared by Day 90. At Day 21both graft cells and the cells of the recipient tendon showed intense collagen synthetic activity. At the same time both graft and host tendon cells began to show signs of apoptosis which continued till Day 90. Subcutaneous tissue and paratenon maintained a much higher level of cellularity, cell proliferation, collagen synthesis and apoptosis at all time. The interplay between cell activity and cell death appear to play central role in the integration of the tendon graft. The persistence of tissue engineered tendon constructs was far less than syngenic or autografts. The Achilles tendon model proved to be a robust and economically viable model for testing of biomaterials particularly at the early stage of their development. Conclusion: The cells of tendon grafts persist only for a finite time before being repopulated by host cells. Tissue engineered cell-based constructs do not provide sufficient persistence to substitute in place of syngenic or autologous graft options. Future designs of engineered tendon should facilitate tendon integration and aim to persist for longer periods of time in order to participate in the healing process.
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Gorey, Colleen Michelle. "Grafting of Stimuli-Responsive Polymer Films to Ultrafiltration Membranes". Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1209667235.
Testo completoAbstract (sommario):
Thesis (M.S.Ch.E.)--University of Toledo, 2008.Typescript. "Submitted as partial fulfillments of the requirements for the Master of Science in Chemical Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 41-45.
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Cuoq, Fabrice. "Fonctionnalisation d’un nouveau matériau pour le traitement de l’eau potable par floculation lestée". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4337.
Testo completoAbstract (sommario):
Le but de ce projet a été d'améliorer un procédé de clarification développé par VEOLIA Environnement : l'Actiflo®. L'Actfilo® est basé sur l'ajout de microsable lors de l'étape de floculation afin d'augmenter les vitesses de décantation. Toutefois, une importante quantité de polymère est continuellement ajoutée au procédé, et des résiduels de ce dernier peuvent être rencontrés dans les eaux décantées. Notre travail a été de fonctionnaliser (i.e. greffer) le microsable avec un polymère floculant afin de pouvoir recycler en continu le matériau hybride par hydrocyclonage. La fonctionnalisation par « Grafting Onto » a consisté à greffer un polymère floculant commercial sur le microsable alors que la fonctionnalisation par « Grafting From » a consisté à faire croître un polymère floculant depuis la surface. Les capacités floculantes des microsables ont été testées en essais classiques de coagulation/floculation. Les microsables fonctionnalisés avec un polymère cationique par « Grafting From » ont démontré leur supériorité en conduisant à un abattement en Carbone Organique Dissous (COD) de 25% contre un abattement de 15 % pour le procédé classique ou pour les microsables fonctionnalisés par « Grafting Onto ». Une turbidité légèrement supérieure est toutefois toujours obtenue avec les sables fonctionnalisés par rapport à l'ajout de polymère libre (+ 0,5 NTU). Enfin, des procédés de régénération permettant de réutiliser les microsables ayant servi en coagulation/floculation ont été mis en place, le plus efficace d'entre eux étant un traitement à base d'Acide Oxalique. Ce traitement a permis de régénérer les propriétés floculantes du sable sur deux cyclesThe purpose of this project was to improve a clarification process developed by VEOLIA Environment: The Actiflo®. The Actfilo® is based on adding microsand in the flocculation stage in order to increase the speed of sedimentation. However, a significant amount of polymeric flocculant is continuously added to the process, and residuals can be found in the decanted water. Our work was to graft a polymeric flocculant onto microsand in order to recycle the full hybrid material through hydrocycloning. Functionalization by "Grafting Onto" was based on grafting a commercial polymer onto microsand whereas “Grafting From” was based on surface-initiated polymerization. Flocculation properties of functionalized microsands were then tested in conventional coagulation/flocculation tests where the effectiveness of the two grafting methods was compared. Cationic functionalized sands, obtained by “Grafting From”, exhibit the best properties as a decrease of Dissolved Organic Carbon of 25% was reached whereas a decrease of 15% was reached by adding free polymer or adding sands from the “Grafting Onto” method. However final turbidity value was always slightly lower for the flocculation that occured when free polymer was added (- 0,5 NTU). Finally, regeneration processes to recycle the functionalized sands were established. The most effective of them being a treatment with Oxalic Acid. This treatment allowed us to regenerate flocculating properties of functionalized sands twice
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Kroggel, Mark, e Chieri Kubota. "Potential Yield Increase by Grafting for Watermelon Production in Arizona". College of Agriculture, University of Arizona (Tucson, AZ), 2017. http://hdl.handle.net/10150/625432.
Testo completoAbstract (sommario):
7 p.Grafting cucurbits onto rootstocks resistant to diseases and abiotic stresses can be a methodto overcome limited availability of effective pre-plant fumigants or land to rotate and to allowearlier planting. Commonly used rootstocks for cucurbits have resistance to Fusarium (race1&2) as well as cold tolerance, among other favorable traits like increased vigor of the scion. Grafting of cucurbits was developed in Asia primarily to allow production without rotation, because arable land is so limited. In the US, crop rotation schedules for seedless watermelon can be 3 years or longer reducing the amount of watermelon a grower can produce in a season. We have been growing grafted and non-grafted seedless watermelon on the same field/plot for 4 years, with no fumigation or off-season rotation of other crops. During the last 2 years, we planted early (March 1) to determine if grafting could overcome low night temperatures in addition to disease pressures. Treatments included grafted and non-grafted plants, covering with frost protection and non-covered. The results of the last 2 years indicate that grafted plants yielded nearly twice as much as non-grafted plants, suggesting that grafting can be a promising technology for Arizona watermelon producers.
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Nuss, Stefan. "Polymermodifizierung von Metall- und Halbleiternanopartikeln durch ATRP "grafting from"-Polymerisation". [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=977228878.
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Steuer, Johnny. "Perioperative Myocardial Damage and Morbidity after Coronary Artery Bypass Grafting". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4199.
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Gibson, Patrick H. "The prediction of atrial fibrillation following coronary artery bypass grafting". Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165981.
Testo completoAbstract (sommario):
Atrial fibrillation (AF) is one of the most frequent complications following coronary artery bypass grafting (CABG), occurring in up to 40% of patients. This thesis investigates the utility of non-invasive markers of left ventricular filling pressure in predicting AF in this setting, and assesses a novel marker of inflammation in the same role. Given the haemodynamic changes occurring peri-operatively it was hypothesised that acute changes in left ventricular filling pressure (LVFP), and resulting atrial stretch, might predispose to post-operative AF. Levels of the natriuretic peptides, BNP and NT-proBNP, were measured pre-operatively in 275 patients undergoing non-emergency CABG, and detailed echocardiographic examination performed. The natriuretic peptides were higher in patients who developed AF, and both were independently predictive of post-operative AF in multivariable analysis. However, their clinical utility appears modest in this role. The only significant echocardiographic predictors of AF were the transmitral E to A-wave ratio and the early mitral annulus velocity. None of the echocardiographic parameters remained independently predictive in multivariable analysis. The strongest echocardiographic correlate of both BNP and NT-proBNP was the left atrial volume index (LAVi), a marker of chronic LV filling pressure. Patients undergoing CABG are subject to a significant peri-operative inflammatory response. This was investigated in the same cohort by means of the neutrophil/lymphocyte (N/L) ratio. Patients who developed AF had greater pre- and post-operative N/L ratios, with no preoperative differences observed in other white blood cell parameters or C-reactive protein. In multivariate models, a greater post-operative N/L ratio was independently associated with the incidence of AF. In patients undergoing CABG, AF remains difficult to predict from pre-operative variables, although age appears to be a consistent factor. Difficulties in the prediction of AF in this setting are likely to reflect the heterogeneity of influences on the development of the arrhythmia in this setting.
47
Richardson, Ffiona. "Development of in vitro grafting technology for Bramley's Seedling Apple". Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324856.
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Au, Yin-Nei Heather. "Development of grafting strategies for the polymer functionalisation of graphene". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/50688.
Testo completoAbstract (sommario):
Graphene is well-known for its exceptional mechanical, electrical, and thermal properties, but its potential is yet to be fully realised in bulk applications due to difficulties in obtaining a large yield of high-quality individually-dispersed graphene sheets. In this thesis, reductive exfoliation of bulk graphite is demonstrated as a promising and versatile method which allows the isolation of single- and few-layer graphenes; the production of reduced graphene, or ‘graphenide’, solutions shows varying efficiency in different solvents. Subsequent functionalisation of graphenide dispersions with various electrophiles, including 1-bromododecane, anionic monomers such as methyl methacrylate, and bromine, results in increased solubility in organic solvents, without damage to the graphene basal plane. Exact characterisation and quantification of grafting is complicated by the presence of solvent remaining between graphene layers, a phenomenon which is not significant in other carbon nanomaterials. Reductive alkylation was carried out on five different graphitic starting materials including two types of natural flake graphite, shear-exfoliated graphite platelets, graphite nanofibres, and few-layer graphene. The study reveals pronounced differences in the obtained grafted species with respect to the degree of functionalisation and residual solvent, exfoliation efficiency and product homogeneity. These results are shown to be dependent on the size and nature of the starting material, with few-layer graphene showing the highest grafting ratios. Few-layer graphene was also functionalised with various molecular weight poly(methyl methacrylate) (PMMA) polymers by grafting-to and grafting-from approaches; the grafting ratios were higher for the grafting-from approach and the products showed a far greater dispersibility in acetone (up to 920 µg/mL). In parallel with these direct polymer-grafting strategies on few-layer graphene, the reduction method was used to dissolve and brominate few-layer graphene sheets, achieving direct covalent attachment of bromine to the graphene framework. The brominated few-layer graphenes provide a convenient, stable, liquid-phase precursor, suitable for the synthesis of a variety of directly functionalised graphenes. As an example, the brominated species was used to initiate atom transfer radical polymerisation, to obtain PMMA-grafted graphene, which was six times more dispersible in acetone than controls. In addition, brominated graphene is active for nucleophilic substitution reactions, as illustrated by the preparation of methoxypolyethylene glycol- and hydroxyl-substituted derivatives. Grafting ratios for these polymer-functionalised materials varied between 6 and 25% and all graphene derivatives showed increased solubility in organic solvents, highlighting the potential of this route for preparing large quantities of dispersed graphene with minimal damage to the carbon framework.
49
Hossain, Mohammed A. "Studies on grafting in the Leguminosae using in vitro techniques". Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/14105.
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Brambilla, Rodrigo. "Sílicas funcionalizadas com octadecilsilano pelos métodos sol-gel e grafting". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10993.
Testo completoAbstract (sommario):
No presente estudo, sílicas funcionalizadas com grupos octadecilsilano (ODS) foram obtidas pelas rotas de grafting e sol-gel. Na rota grafting foram variadas as temperaturas de pré-tratamento da sílica comercial na faixa de 100-450 °C. Na rota sol-gel, foram variadas as razões molares ODS: TEOS, o instante de adição do ODS e a velocidade de agitação da reação. As sílicas foram caracterizadas em termos do teor de carbono, da natureza das espécies imobilizadas, da textura e morfologia pelas técnicas complementares de Análise Elementar (CHN), Espectroscopia Fotoeletrônica de Raios-X (XPS), Espectroscopia molecular no Infravermelho com Transformada de Fourier (FTIR), Espectroscopia de Ressonância Magnética Nuclear de 29Si e 13C (NMR de 29Si e 13C), Adsorção de nitrogênio, Análise Termogravimétrica (TGA), Espalhamento de Laser (LLS), Espectroscopia de Espalhamento de Raios-X em Baixo Ângulo (SAXS), Microscopia de Força Atômica (AFM) e Microscopia Eletrônica de Varredura com Espectroscopia de Emissão de Raios-X por Dispersão de Energia (SEM-EDX).As sílicas funcionalizadas por grafting apresentaram teores de carbono determinados por CHN na faixa de 1,2-3,5 %, morfologia irregular e conformação de grupos ODS próxima ao estado líquido. Já as sílicas funcionalizadas por sol-gel, apresentaram teores de carbono na faixa de 5,0-53 %, combinação de morfologia esférica com lamelar e conformação de grupos ODS próximas ao estado cristalino. A potencialidade das sílicas funcionalizadas como adsorventes de compostos aromáticos em amostras ambientais de água e ar foi avaliada.In the present study, octadecylsilane-modified silicas were obtained by the grafting and the sol-gel methods. In the grafting route, silica pretreatment temperature was varied between 100 and 450 °C. In the sol-gel one, the following variables were evaluated: ODS:TEOS molar ratio, ODS addition time and stirring speed. The resulting silicas were characterized in terms of carbon content, nature of the surface species, texture and morphology by a set of complementary techniques, namely: elemental analysis (CHN), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy with Fourier Transform (FTIR), 29Si e 13C nuclear magnetic resonance (29Si e 13C NMR), nitrogen adsorption, thermogravimetric analysis (TGA), laser-light scattering (LLS), small angle X-ray scattering (SAXS), atomic force microscopy (AFM) and electron scanning microscopy combined with energy dispersive X-ray analysis (SEM-EDX). Chemically-modified silica by grafting presented low carbon content in the range of 1.2 – 3.5 wt.%, irregular morphology and ODS conformation groups close to the liquid state. Hybrid silica prepared by the sol-gel method showed carbon contents between 5.0 and 53.0 wt.%, combining spherical and lamellar morphology, and ODS groups conformation close to the crystalline state. The potentiality of the chemically-modified silicas as sorbents for aromatic compounds was evaluated in environmental water and air matrices.