Membranes are essential components of all living organisms forming the borders of cells and their organelles. Planar lipid membranes deposited on solid substrates (solid supported membranes) provide models to study the functions of membrane proteins and are used as biosensing platforms. However, despite remarkable progress, solid supported membranes are not stable to harsh conditions such as dehydration, high temperature and pressure, and mechanical stress. In addition, the direct deposition of membranes onto a solid substrate often causes restricted mobility and denaturation of reconstituted membrane proteins. Membrane stability can be addressed by altering the structure of the component lipids. Bolalipids are an interesting class of bipolar lipids that have been proposed for biosensing applications. Membranes formed from mixtures of a bolalipid, C20BAS, and dioleoylphosphaphatidylcholine, POPC, were characterized by atomic force spectroscopy (AFM). The lipid mixtures produced a phase separated membrane consisting of thinner bolalipid-rich and thicker monopolar-rich POPC regions, with a height difference of approximately 1-2 nm. This confirmed an earlier prediction that some bolalipid/PC membranes would phase separate due to the hydrophobic mismatch between the two lipids. Interestingly, the surface coverage of the two phases was inconsistent with what one would expect from the initial starting lipid ratios. The complex membrane morphologies observed were accredited to the interplay of several factors, including a compositionally heterogeneous vesicle population, exchange of lipid between the vesicle solution and solid substrate during formation of the supported membrane, and slow equilibration of domains due to pinning of the lipids to the solid support. Decoupling the membrane from its underlying surface is one strategy to maintain the structure and mobility of membrane proteins. This decoupling can be achieved by depositing the membrane on a soft cushion composed of a water swelling hydrophilic polymer. A polyelectrolyte multilayer (PEM) and a tethered poly(ethylene) glycol (PEG) polymer are the two types of polymer cushions used in this study. The PEMs consist of the charged polysaccharides, chitosan (CHI) and hyaluronic acid (HA) which offer the advantage of biocompatibility over synthetic PEMs. DOPC lipid bilayers were formed at pH 4 and 6.5 on (CHI/HA)5 films. At higher pH adsorbed lipids had low mobility and large immobile lipid fractions; fluorescence and AFM showed that this was accredited to the formation of poor quality membranes with defects and pinned lipids rather than to a layer of surface-adsorbed vesicles. However, more uniform bilayers with mobile lipids were produced at pH 4. Measured diffusion coefficients were similar to those for bilayers on PEG cushions and considerably higher than those measured on other polyelectrolyte films. The results suggest that the polymer surface charge is more important than the surface roughness in controlling formation of mobile supported bilayers. The suitability of polymer supported membranes for the incorporation of integral membrane proteins was also assessed. The integral membrane protein Ste14p, a 26 kDa methyltransferase enzyme, was reconstituted into POPC membranes on PEM and PEG supports. A combination of fluorescence microscopy, FRAP, AFM and an in situ methyltransferase activity assay were utilized to characterize the protein incorporated polymer supported membranes. Fluorescence measurements showed that more protein was incorporated in model membranes formed on the PEG support, compared to either glass or PEM cushions. However, the protein activity on a PEG support was comparable to that of the protein in a membrane on glass. FRAP measurements showed that the lipid mobilities of the POPC:Ste14p bilayers on the various supports were also comparable. Lastly, as a new platform for manipulating and handling membrane proteins, nanodiscs containing reconstituted Ste14p were studied. Nanodiscs are small, soluble and stable bilayer discs that permit the study of membrane proteins in a uniform phospholipid bilayer environment. Empty and protein containing nanodiscs were deposited on a mica surface and imaged by AFM. AFM showed that protein containing samples possessed two subpopulations of nanodiscs with a height difference of ~1 nm. The taller discs, ~20% of the population, contained protein. Other experiments showed that the packing of the nanodisc samples was influenced by their initial stock concentration and that both imaging force and the addition of Mg2+ caused formation of larger bilayer patches.

The Diploma thesis is dedicated to design of a hovercraft. The concept of design is a small hovercraft for personal use. The hovercraft is styled into a sports category. The interior is designed for 4 persons and personal luggage. Main part of the work is the exterior of the hovercraft. But it contains also a basic vision of interior solution with basic dimensions according to antropometric measures and other ergonomical criteria. So the result is original hovercraft, which is solved in area of design with regards for ergonomics and technological limitations, which hovercraft brings.

The work presented herein describes the production of hot strip with special attention to the runout table. Because of its high capital and operating costs, a new principle in conveying the strip using an air cushion and a new cooling system for strip cooling have been proposed. Information given here is nearly all from available literature and the author's own experience with Hot Strip Mill production problems. To support the idea of using an air cushion for strip conveying, experimental equipment was designed and built which confirmed the feasibility of the method. A new cooling system was also proposed to meet the ever increasing requirements for better mechanical properties of hot strip. Runout table design application may serve as a guideline in designing new Hot Strip Mill runout table. / Thesis / Master of Engineering (ME)

Mechanical factors have been cited as a primary cause of total knee replacement failure. A hypothesis has been formulated stating that the introduction of a compliant interface into a total knee prosthesis would moderate excessive stresses and strains, thereby, extending joint life. A biocompatable elastomer developed by the Dow Corning Corporation was selected for mechanical evaluation as a cushioning material. Force-strain, impact, and fatigue tests were conducted on several specially designed and fabricated elastomer test shapes. Test results demonstrate that a suitably stiff and dynamically responsive elastomer cushion can be designed to handle repeated physiological knee joint loads. Physiological impacts with cadaver tibias demonstrated significant shock reduction benefits, including peak force reductions of up to 70%, with the addition of different elastomer shapes. Compressive fatigue evaluation of elastomer samples was inconclusive owing to extensive sample wear. As a result configurations or applications where the elastomer can move relative to a rigid surface are not recommended. A new, mechanically contained elastomer shape was designed and tested which greatly reduced wear. Bonding of this new shape to prosthetic joint materials is recommended for further experimental evaluation. / Thesis / Master of Engineering (ME)

In this work the infrared absorption of neutron irradiated silicon was compared to that of non-irradiated silicon at room and liquid nitrogen temperatures. It was found that instead of the 1.75 micron absorption band that has been mentioned in numerous papers transmission was completely cut off below about 2.5 microns at room temperature and about 1.8 microns at liquid nitrogen temperature. A weak absorption band was noted at 4.4 microns for all three samples at liquid nitrogen temperature and the two irradiated samples at room temperature. Absorption due to free carriers depressed at the longer wavelengths (10-15 microns) with irradiation and cooling as was expected from past experiments. The resistivity of Si₄ increased from an assumed initial value of 10³ ohm-om to 1.89 x 10⁵ ohm-om. / Master of Science

Löpning är en av de största fysiska aktiviteterna runt om i världen. Det räknas med att 37-56 % av alla som löper någon gång drabbas av en skada i samband med löpningen. Studiens syfte är att undersöka effekten av olika dämpningsmaterial, drop samt motion-kontroll av löparskor på skadefrekvens i samband med pronation och supination under löpning. Studien gjordes som en litteraturstudie där 11 vetenskapliga artiklar ingick i studien. Resultatet visar att motion-kontroll skor rekommenderas till pronerande löpare och neutrala skor till supinerande eller neutrala löpare. Minskat drop leder till minskad skaderisk. Framfotslöpning är att föredra jämfört med häl till tå löpning. En mjuk sula är bättre vid kortdistans och en hårdare sula vid långdistans. EVA material visade på en bättre återhämtningseffekt än TPU.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

A coleta de sêmen da cauda do epidídimo é a última oportunidade de obter espermatozoides de garanhões valiosos, sendo que durante a criopreservação, a etapa de centrifugação é considerada um ponto crítico. A principal hipótese é que a centrifugação com coloides pode melhorar a qualidade dos espermatozoides coletados da cauda do epidídimo de garanhões. Para avaliação da hipótese foram realizados dois experimentos. O experimento um teve por objetivo avaliar o efeito da centrifugação com cushion e com coloide em camada única (SLC) na motilidade de sêmen do epidídimo de garanhões após a etapa de centrifugação. O experimento dois teve o objetivo de determinar o efeito da SLC prévio ao congelamento e após o descongelamento. Experimento 1) Oito garanhões foram submetidos à orquiectomia bilateral e o sêmen foi coletado da cauda dos epidídimos (n=16). Após a coleta, as amostras foram submetidas a três protocolos de centrifugação: Convencional (20 minutos a 600xg), cushioned (20 minutos a 900xg) e SLC (20 minutos a 300xg). Os pellets foram ressuspendidos e as amostras foram submetidas à avaliação laboratorial de motilidade e morfologia espermática. Experimento 2) Dez garanhões foram submetidos a orquiectomia bilateral e o sêmen foi coletado da cauda dos epidídimos (n=20). Para criopreservação, as amostras foram submetidas a: centrifugação convencional (20 minutos a 600xg), SLC prévio a criopreservação (SLC-Pre) (20 minutos a 300xg) e SLC após a criopreservação (SLC+) (20 minutos a 600xg seguidos de uma segunda centrifugação descrita após descongelamento). Os pellets foram ressuspendidos em diluente de congelamento, submetidos ao processo de congelamento em nitrogênio líquido e descongelamento. Os grupos de 6 centrifugação convencional e SLC-Pre foram avaliados imediatamente após descongelamento. O grupo SLC+ foi descongelado e submetido à SLC (20 minutos a 300xg) e ressupendido em diluente de congelamento (SLC+F) ou resfriamento (SLC+C). A motilidade total e a motilidade progressiva das amostras foram avaliadas com análise computadorizada do movimento espermático. A morfologia foi avaliada com auxílio de microscópio com contraste de fase. Funcionalidade de mitocôndria, integridade de membrana e DNA foram avaliados com auxílio de microscópio de fluorescência. Os dados foram analisados por estatística descritiva, simple one-way ANOVA e Teste de Tukey. Experimento 1) a motilidade de espermatozoide submetidos à SLC (p<0,05) e cushion (p>0,05) foi superior do que os submetidos a centrifugação convencional. Experimento 2) SLC-Pre e SLC+F apresentaram maior motilidade total, enquanto SLC+F apresentou maior motilidade progressiva. O percentual de espermatozoides com morfologia normal foi maior em SLC-Pre e SLC+F. A funcionalidade de mitocôndria foi maior em todos grupos com SLC, enquanto a integridade de membrana foi maior em SLC-Pre. A centrifugação com coloides melhorou a qualidade de espermatozoides coletados da cauda do epidídimo de garanhões, tanto no momento prévio ao congelamento como após o descongelamento. / Epididymis cauda sperm recovery and cryopreservation are last opportunity to obtain spermatozoa from a valuable animal, even though during cryopreservation centrifugation step is considered as a critical point. It is hypothesized that colloidal centrifugation could enhance epididymal stallion sperm parameters. To evaluate this hypothesis two experiments were performed. In experiment one, the objective was to evaluate the effect of cushioned and Single Layer Centrifugation (SLC) on epididymal stallion sperm motility postcentrifugation. In experiment two, the objective was to determine the effect of SLC on epididymal stallion sperm quality pre-freezing and post-thawing. Experiment 1) Eight stallions were submitted to bilateral orchiectomy and the resulting epididymal cauda (n = 16) were flushed with semen extender. After harvesting, samples were submitted to three centrifugation protocols: conventional (20 minutes at 600xg), cushioned (20 minutes at 900xg), and SLC (20 minutes at 300xg). Pellets were resuspended, motility and morphology were evaluated. Experiment 2) Ten stallions were submitted to bilateral orchiectomy and epididymal cauda (n=20) were harvested. For cryopreservation, epididymal sperm were submitted to: conventional centrifugation (20 minutes at 600xg), Single Layer Centrifugation prior cryopreservation (SLC-Pre) (20 minutes at 300xg) and Single Layer Centrifugation after cryopreservation (SLC+) (20 minutes at 600xg followed by a second centrifugation described after thawing). Pellets were resuspended in freezing extender, submitted to cryopreservation process in liquid nitrogen and thawed. Conventional and SLC-Pre were evaluated immediately after thawing. SLC+ samples were thawed, submitted to SLC (20 minutes at 300xg) and the pellets were resuspended with freezing (SLC+F) and cooling extender (SLC+C). Total motility (TM) and progressive 8 motility (PM) were evaluated with computer-assisted semen analyses. Sperm morphology was evaluated under a phase-contrast microscope. Mitochondrial functionality, membrane e DNA integrity were evaluated with an epifluorescence microscope. Data was evaluated by descriptive statistics, simple one-way ANOVA and comparison between means by Tukey test. Significance was assigned to all values p<0.05. Experiment 1) Motility of spermatozoa recovered by SLC (p<0.05) and cushioned centrifugation (p>0.05) were higher than those recovered by conventional centrifugation. Experiment 2) SLC-Pre and SLC+F yielded the highest TM, while SLC+F yielded the highest PM. Higher morphological normal sperm was observed in SLC-Pre and SLC+F. Mitochondrial functionality was significantly higher in all treatments with SLC, while membrane integrity was higher in SLC-Pre. Colloidal centrifugation improved epididymal sperm quality before freezing and after thawing.

Submitted by Sandro Camargo (sandro.camargo@unipampa.edu.br) on 2015-03-08T20:08:58Z No. of bitstreams: 1 127110020.pdf: 531553 bytes, checksum: 0170d654c8a7662821baf128927374e8 (MD5) / Made available in DSpace on 2015-03-08T20:08:58Z (GMT). No. of bitstreams: 1 127110020.pdf: 531553 bytes, checksum: 0170d654c8a7662821baf128927374e8 (MD5) Previous issue date: 2014-08-12 / A técnica de seleção espermática para fecundação in vitro (FIV) deve proporcionar além, da recuperação eficiente de espermatozoides, a manutenção da integridade celular. Diversos métodos vêm sendo propostos para a seleção de espermatozoides bovinos destinados a FIV, sendo o método de centrifugação em gradientes de densidade descontínuos de Percoll® o mais utilizado. Em bovinos esta técnica de seleção vem sendo amplamente modificada no que se refere ao volume, número de gradientes, tempo e força de centrifugação, visando aumentar a recuperação espermática, proporcionando um melhor rendimento da dose. Contudo, a etapa de centrifugação, presente nestes protocolos, pode causar danos irreversíveis aos espermatozoides e assim influenciar nas taxas de fecundação. O presente estudo teve como objetivo determinar a influência da força e do tempo de centrifugação, assim como a associação do meio Cushion Fluid® na segunda centrifugação na seleção espermática por gradientes de Mini Percoll® modificado, através da avaliação de características morfofuncionais, formação de espécies reativas ao oxigênio (EROs), defesas antioxidantes, taxa de fecundação in vitro e desenvolvimento embrionário em três experimentos. No experimento I, um pool contendo sêmen de dois touros Bos taurus taurus com fertilidade conhecida foi submetido ao método de separação por Mini Percoll®, sendo as amostras divididas em quatro grupos e submetidos a duas forças (2200 ou 9000 X g) e dois tempos de centrifugação (1 e 3 minutos). No experimento II e III, um pool de sêmen de dois touros Bos taurus taurus com fertilidade conhecida foram processados pelo método de Mini Percoll® modificado, sendo adicionado uma quantidade de 150μL de Cushion Fluid® (Minitübe, Tiefenbach, Germany) durante a segunda centrifugação. Foram realizadas avaliações morfofuncionais e bioquímicas das amostras do sêmen destinado a FIV, assim como a capacidade fecundante e o desenvolvimento embrionário dos oócitos fecundados com os espermatozoides selecionados. No primeiro experimento foi observada uma melhora no vigor dos espermatozoides após o gradiente de Mini Percoll®, para todos os tratamentos. No segundo experimento, a taxa de recuperação espermática não diferiu entre os tratamentos, sendo 42,0% ± 4,9 para T1 e 38,6% ± 3,6 para T2 (grupo com adição do Cushion Fluid® na segunda centrifugação):. Na morfologia espermática o T2 (5,1 ± 1,1) apresentou menor taxa de espermatozoides com defeitos maiores do que os tratamentos T0 (Pré-Percoll) e T1 (8,8 ± 0,8 e 5,8 ± 1,0). Neste mesmo experimento, os níveis de EROs apresentaram-se aumentados (P < 0,05) no meio com Cushion Fluid® (T2), no entanto, a avaliação das defesas antioxidantes não diferiram entre os tratamentos. No experimento III, não foram observadas diferenças na taxa de fecundação. Este trabalho demonstrou que o uso de uma menor força e tempo (2200 X g/1 min.) de centrifugação pode ser utilizado sem interferir nas taxas de recuperação espermática. O uso do meio Cushion Fluid® durante a centrifugação de espermatozoides bovinos não influenciou a taxa de fecundação e desenvolvimento embrionário até 48 horas. / The technique of sperm selection for in vitro fertilization (IVF) should provide addition, the sperm efficient recovery, the maintenance of cellular integrity. Several methods have been proposed for bovine sperm selection for IVF, and the discontinuous density gradients Percoll® ( Sigma Aldrich – St. Louis MO, USA) centrifugation method on the most used. In cattle this selection technique has been extensively modified with respect to the volume, number of gradients, time, and centrifugal force, to increase the sperm recovery, providing a better yield of the dose. However, the centrifugation step present in these protocols, may cause irreversible damage to sperm and thus influence fertilization rate. The present study aimed to determine the influence of centrifugation force and time, as well as the association of the Cushion Fluid® centrifugation on sperm selection by gradients Mini Percoll® modified by evaluating morphological and functional characteristics, ROS formation, antioxidant defenses, rate of in vitro fertilization and embryo development. Three experiments carry out. In experiment I, a pool containing two semen Bos taurus taurus bulls was subjected Mini Percoll® separation method, samples being divided into four groups, with two centrifugal forces (2200 or 9000 X g) and two times (1 and 3 min). In experiment II and III, the pool has been processed by the Mini Percoll® modified method, being added to an amount of 150μLix of Cushion Fluid® (Minitübe, Tiefenbach, Germany) in the second centrifugation in the treated group. Morphofunctional and biochemical evaluation of semen samples for IVF, as well as the fertilizing capacity and embryo development of oocytes fertilized with sperms were selected performed. In the first experiment an improvement was observed in the vigor of sperm after gradient Mini Percoll® for all treatments. In the second experiment, the recovery rate sperm did not differ between treatments (T1: 42.0 ± 4.9 and T2 (with adding Cushion Fluid® the second centrifugation): 38.6 ± 3.6). In sperm morphology T2 (5.1 ± 1.1) showed a lower sperm rate with major defects than T0 (Pre-Percoll) and T1 (8.8 ± 0.8 and 5.8 ± 1.0 treatments ). In this same experiment, ROS levels were presented increased (P <0.05) in the medium with Cushion Fluid® (T2), however, the evaluation of antioxidant defenses did not differ between treatments. In experiment III, no differences in fertilization rate were observed. This study demonstrated that the use of a smaller force and time (2200 X g / 1 min.) to centrifugation can be used without interfering with the sperm recovery rate. The use of the medium Cushion Fluid® during centrifugation of bovine sperm did not influence the fertilization rate and embryo development to 48 hours.

The aim of this study is to develop new insights which pressure relief (PR) cushion designers can use to guide the design of new cushions with greater efficacy at preventing pressure ulcers than contemporary cushions. A methodological framework was formulated which incorporated a number of research techniques from the user-centred methodology USERfit, and included methodological triangulation. Exploratory interviews and observational work were conducted in a specialist unit for spinal cord injury (SCI). This involved ten patients, four physiotherapists, two nurses and an outpatient technician. Additionally, two questionnaires were designed and circulated amongst SCI patients and staff with completed responses from 41 patients and 31 staff. From the analyses of the data gathered from the literature, observational work, interviews and questionnaire responses, 28 recommendations for cushion design were formulated. These recommendations covered the principles which underpin cushion design, cushion usability and the future direction of cushion design.