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SAMMANFATTNING   Bakgrund: Trycksår är en lokal skada i huden och i underliggande vävnad som kan uppkomma i samband med sjukdom, vård och behandling. Trycksår betraktas idag som en vårdskada och ska anmälas som en avvikelse. För individen innebär det stort lidande och ger höga kostnader för samhället, större omvårdnadsbehov och förlängda vårdtider. Studier visar att kunskap om trycksårsprevention hos sjuksköterskor och undersköterskor i Sverige inte är tillräckligt hög. Ett trycksensorsystem (MAP-system) finns nu tillgängligt som ger omedelbar feedback av patientens tryckpunkter som ett hjälpmedel vid trycksårsprevention. Syfte: Att utvärdera effekten av MAP- systemet avseende förekomst av trycksår hos äldre patienter under vårdtiden på en geriatrisk avdelning på sjukhus. Metod: En randomiserad, kontrollerad studiedesign valdes. En geriatrisk vårdavdelning valdes ut med en MAP-grupp (n=91) och en kontrollgrupp (n=99). Ett studieprotokoll användes med uppgifter om: demografisk data, hudinspektion (trycksårsklassificering kategori 1-4), Modifierad Nortonbedömning, komfort, maxtryck samt preventiva åtgärder. Insamlad data behandlades i SPSS och signifikansberäkning, standardavvikelse och medeltal räknades ut. Resultat: Användande av MAP-systemet gav ingen signifikant skillnad i andelen patienter med trycksår mellan MAP- och kontrollgruppen. Andel patienter med trycksår i MAP-gruppen dag ett var 24,2 % och dag 14, 28,2 %. I kontrollgruppen var andelen dag ett 18,2 % och dag 14, 23,8 %. Vanligaste lokalisationen av trycksår var hälar därefter sakrum och glutealt. Patienter med trycksår fick signifikant fler trycksårsförebyggande åtgärder. Slutsats: Studien visar ingen signifikant skillnad mellan andelen patienter med trycksår i MAP- och kontrollgruppen. Preventiva åtgärder prioriterades främst till patienter med trycksår. Genomförandet av studien antas ha medfört ökat fokus på trycksårsprevention samt påverkat prevalensen av trycksår positivt på den aktuella avdelningen. / ABSTRACT   Background: Pressure ulcers consist of local damage to the skin and underlying tissue and can occur in relation to illness, care and treatment. Pressure ulcers are today considered as an adverse event and are to be reported as a deviation from care routines. For the individual it can be the source of great suffering. It also generates large costs for the community, increased needs of nursing as well as prolonged periods of hospitalization. Studies show that the level of knowledge among registered nurses and assistant nurses in Sweden is insufficient. A pressure mapping system (MAP system) is now available, and can provide immediate feedback about the patient´s pressure points as a tool for pressure ulcer prevention. Aim: To study the effect of the MAP system regarding the presence of pressure ulcers in elderly hospitalized patients on a geriatric ward. Method: A randomized, controlled study design was chosen. A geriatric ward was selected with a MAP group (n=91) and a control group (n=99). A study protocol containing demographic data, systematic skin inspection (with classification of pressure ulcers category 1-4), Modified Norton scale, comfort, maximum pressure and preventive measures was used. Data was processed in SPSS; generating mean, standard deviation and level of significance. Results: No significant difference in the prevalence of pressure ulcers was shown between the MAP- group and the control group. The prevalence of pressure ulcers in the MAP-group was 24,2 % on day one and 28,2 % on day 14. In the control group the corresponding numbers were 18,2 % and 23,8 %. The most common localization of pressure ulcers were heels, followed by the sacral and gluteal regions. Patients with pressure ulcers received significantly more preventive measure compared to patients without pressure ulcers. Conclusion: The study shows no significant differences between the groups regarding the prevalence of patients with pressure ulcers. Preventive measures were prioritized mostly for patients with existing pressure ulcers. The study is assumed to have increased the focus on pressure ulcer prevention thus affecting the prevalence of pressure ulcers in a positive way on the present ward.

Fretting fatigue is a major concern in the design of engineering components that will be subjected to clamping pressures whilst operating in a vibrational environment. The type of loading environment generated in these applications is generally of a variable amplitude nature. Therefore it is important for engineers to understand how such loading affects the severity of fretting fatigue. In the absence of this understanding, engineering designers are left to apply simplistic plain fatigue life prediction rules, such as Miners linear damage law, to try to estimate the damage generated from a particular loading history. In order to try to establish a baseline for the understanding of fretting fatigue under variable amplitude loading, a structured series of CAL and V AL tests were designed and carried out. The aim of the CAL tests was to characterise the fretting fatigue test rig (designed by the author) so that an experimental foundation could be developed, upon which the fretting fatigue study was based. A structured investigation into the effects on fretting fatigue of applying various specifically designed loading histories was carried out and some very distinct relationships between the applied loading spectra and fretting fatigue life were found. For the application of overloads it was observed that overload size, overload application interval and the number of overloads in each application all had a sizeable effect on the severity of fretting. Two-level, three-level and five-level block loading tests were also investigated and numerous loading history dependent results were obtained. The applicability of Miners law to fretting fatigue was assessed. Combining Miners law with well-defined CAL stress-life results gave reasonable predictions for all of the V AL fretting fatigue tests carried out, with damage summations at failure ranging from 0.64 (non-conservative) to 3.19 (conservative). However, a more detailed investigation into the relationship between fretting fatigue lives and damage summations due to the individual loading levels highlighted that the assumption of linear damage may not be applicable to fretting fatigue, especially during crack initiation and early crack growth. A hypothesis was proposed to explain the fretting fatigue life and Miner damage results observed for the different loading spectra, and reasonable success was obtained for tests where the Miners law proved conservative (in 27 of 36 tests), although the hypothesis was not able to explain the non-conservative results obtained in the other nine tests.

The purpose of this investigation was to study the effects of decreasing barometric pressure upon the pressure-flow relationships in a peripheral vascular bed in an attempt at better delineation of the autoregulatory mechanisms. A decrease in barometric pressure does influence the transmural pressure and could theoretically affect smooth muscle tone. An evaluation of the extent of the transmural effect is essential to understanding vascular dynamics at altitudes.

The application of pressure to chemical substances can change their physical properties (optical, magnetic, and electrical) and it can also be used to alter some chemical reactions. The need for compatible pressure generating instruments is constantly growing in various high pressure (HP) researches. The work described in this thesis is focused on development, construction, testing of several high pressure cells of novel design. These designs were developed to meet the requirements of different research collaborations. The main objective of this project is to develop high pressure cells for magnetic studies in the magnetic properties measurement system known as MPMS, which is the most popular commercial magnetometer nowadays. Three high pressure cells were designed and tested for different type of magnetic measurements. The first design presented in this thesis is a cylinder type pressure cell which is specially designed to measure the magnetic susceptibility of the pressure-sensitive material under pressure. The cell is driven by compressed helium gas which allows the internal pressure to be adjusted with small increments (1 MPa) through the regulator of the external gas cylinder. The cell was made of non-magnetic beryllium copper alloy and designed to work up to 100 MPa at 400 K temperature. The design was verified with finite element analysis (FEA) simulation and its sample volume was optimised to provide large sample capacity which allows high quality data to be collected in the MPMS. Modified from the earlier turnbuckle magnetic diamond anvil cell (TM-DAC) reported in Konstantin V. Kamenev (KVK) group, the second high pressure cell presented in this thesis is an opposed diamond anvil pressure cell. The working mechanism of this cell is based on the turnbuckle principle. The cell was specifically developed for iHelium3 system which is a add-on cryostat of the MPMS. The cell was coded TM-3He-DAC to distinguish with the original TMDAC. The cell is 6 mm in diameter and 7 mm in length, which are smaller than the dimensions of the predecessor (TM-DAC). Copper titanium alloy was used in building the cell to further reduce the magnetic background from the cell. The cell is capable of achieving close to 5 GPa sample pressure in the loading test and the magnetic background is significantly lower than the TM-DAC. The development of this cell enables high pressure magnetic measurements to be performed at extreme low temperature (0.5 K) in the iHelium3 system. The third high pressure cell developed for the MPMS is also a turnbuckle diamond anvil cell, however, all the material used in the cell is non-metallic to enable high-pressure ac magnetic measurement to be performed. An advanced high strength polymer was assessed using finite element analysis and experimental testing. The performance and failure modes for the key components of the cell working in tension and in compression were evaluated and the ways for optimising the designs were established. The cell is coded PTM-DAC in this thesis and the composite gasket was also developed and tested for the PTM-DAC. The cell is approximately 14 mm long, 8.5 mm in diameter and was demonstrated to reach pressures of 5.6 GPa. Ac susceptibility data collected on Dy2O3 and U6Fe demonstrated the performance of the cell in magnetic property measurement and confirmed that there was no screening of the sample by the environment which typically accompanies used of conventional metallic high pressure cells in oscillating magnetic fields. Based on the experience of from the development of above two turnbuckle diamond anvil cell, a turnbuckle sapphire anvil cell (T-SAC) was developed in this project for high-pressure neutron scattering. Commercial spherical sapphire were used as anvil in the cell as they are much more cost effective if compared to the diamond anvil. The developed T-SAC can generate and maintain sample pressures above 6 GPa with a sample volume 6 X 10-² mm³ which is 6 times that of conventional diamond anvil cell (DAC). Failure analysis was performed on the sapphire anvil to gain a better understanding of the failure mechanism of the spherical sapphire anvil. The cell had been used in measuring the crystal structure of single crystal niobium at 1.6 GPa through small angle neutron scattering (SANS) technique. The cell is less than 16 mm in length and 14 mm in diameter, it is the smallest sapphire anvil cell to date. The miniature feature allow it can be fit into most cryostat of modern scientific instrument without difficulties. Lastly, two piston-cylinder type high pressure cells were developed for high-pressure chemistry studies. These cells were designed to pressurise large amount of liquid sample (particular for water-based sample) up to 800 MPa in a controllable manner. Each design is presented separately with stress analysis in FEA and a description of the working mechanism. Hoop strain at the external surface of the cell was measured and then the internal pressure was calculated through the Lam´e equation. After that, the load and attainable internal pressure was calibrated for the users. These cells have been used in the high-pressure study of salicylaldoximes process, bio-diesels decomposition and crystallization, material polymerisation and pharmaceutical experiments.

Master of Science / Department of Clinical Sciences / Warren L. Beard / Objectives: To quantify sub-bandage pressures associated with various bandage constructs applied to the abdomen, distal limb, carpus, and tarsus. To assess the effect of time and /or post-bandaging manipulations on sub-bandage pressures. Study design: Randomized clinical trial Methods: Each bandage’s sub-bandage pressures were measured with the Picopress® compression measuring system at various time points determined by the study protocol. Nine horses were randomly assigned to a treatment regimen consisting of placement of three abdominal bandage types. Bandages were maintained for 24 hours. 8 horses had two types of distal limb bandages (DLC and DLP) applied and maintained for 24 hours. 8 horses had a DLC bandage applied for 96 hours. 8 horses had both carpal and tarsal bandages applied and pressures monitored after application and post walking. A generalized linear model evaluating associations of pressure with location of the sensor, bandage type, time of measurement, and the potential interaction between all variables was performed (P< 0.05). Results: For abdominal bandages, no time and treatment interactions were observed, and bandage pressures were maintained within each treatment group over the 24 hour period. For distal limb bandages, bandage type, sensor location, and time had a significant effect on sub-bandage pressures. For joint bandages, bandage type, sensor location, and post-bandaging manipulations had significant effects on sub-bandage pressures associated with compression bandages. Ambulation did not have a significant effect sub-bandage pressures generated by the carpal elastic bandages. Conclusions: Abdominal sub-bandage pressures do not significantly decrease over a 24 hour period, but generate low sub-bandage pressures. In contrast, limb bandages apply high sub-bandage pressures, but these pressures degrade over the initial 24 hours.

Ph.D., Faculty of Health Sciences, University of the Witwatersrand, 2011 / Contemporary notions of the adverse effects of blood pressure (BP) incorporate the increasingly recognised damaging effects of not only distending pressure (indexed by mean arterial pressure-MAP) but also pulse pressure (PP) (the difference between systolic and diastolic BP) on the cardiovascular system. Although the factors which determine brachial artery PP are similar to those affecting central (aortic) PP (PPc), some factors may affect central PP preferentially, and thus PP calculated from brachial artery BP measurement may not closely reflect the PP that accounts for cardiovascular damage. In order that therapeutic strategies are developed that modify PPc independent of distending pressures, there is considerable interest in the pathophysiological mechanisms that explain increases in PPc. In this regard, aortic PP is comprised of the forward or incident pressure component (P1), which is largely determined by stroke volume, aortic compliance or stiffness and aortic diameter; and the augmented pressure component (AP), which is determined by wave reflection. Whilst currently employed antihypertensive agents may modify AP independent of distending pressures, there is little evidence to indicate a similar effect on the structural aortic changes responsible for P1. Although changes in AP as opposed to P1 largely account for age-related increases in PPc across the adult lifespan in normotensives, the relative contribution of AP and P1 to PPc in communities with a high prevalence of uncontrolled BP is unknown. In 1015 randomly recruited participants (range 16-88 years) from a community sample, 37.7% of whom had uncontrolled BP, I demonstrated that independent of MAP and other confounders, P1 contributes as much as AP to age-related increases in PPc and to variations in PPc across the adult lifespan. As no previous studies have assessed the relationship between P1 and cardiovascular damage, in 503 randomly recruited participants from a community with a high prevalence of uncontrolled BP, the relative contribution of P1 and AP to increases in left ventricular mass index (LVMI) was subsequently evaluated. In this regard, independent of distending pressures, P1 was associated with LVMI, highlighting the need to understand the iii potential mechanisms which contribute to P1. Could the pathophysiological mechanisms that determine hypertension account for the contribution of P1 to PPc? In this regard, I evaluated the potential role of three mechanisms. First, in 635 randomly selected participants with 24-hour urine samples that met with pre-specified quality control criteria, I provide the first data to demonstrate that urinary sodium-to-potassium ratio (an index of Na+ and K+ intake) is independently associated with PPc, but not brachial PP independent of distending pressures, a relationship that could be accounted for by changes in both AP and P1, but not aortic pulse wave velocity. Second, I explored the possibility that low grade inflammation as indexed by circulating high-sensitivity C-reactive protein concentrations (hs-CRP) may contribute toward PPc and the component pressures. In this regard, although hs-CRP has been associated with changes in central haemodynamics in small study samples, in a large community sample of participants these findings could not be reproduced. However, in that study the community had a low prevalence of risk-related hs-CRP concentrations. In 836 randomly recruited participants from a population sample with a high prevalence of risk-related hs-CRP concentrations (~57%), although on univariate analysis I showed that hs-CRP was strongly associated with PPc and the component pressures, this relationship did not persist with adjustments for confounders. Last I evaluated the potential contribution of genetic factors toward PPc and the component pressures. Although three prior studies had demonstrated heritability of PPc, AP and P1, two studies failed to adjust for MAP and a third assessed the heritability in females only. In none of these studies was the contribution of aortic PWV to the heritability estimates of PPc, AP and P1 assessed. In 568 participants from 183 nuclear families, I showed that independent of MAP, multivariable adjusted PPc, AP, P1 and PWV aggregated in families and were inherited. However, adjustments for aortic PWV failed to modify the extent of intrafamilial aggregation and heritability of PPc, AP, or P1. In conclusion, in the present thesis I have advanced our understanding of the mechanisms responsible for increases in PPc. In this regard, I provide evidence to suggest that independent of distending pressures and stroke volume, P1 accounts for a significant iv proportion of the age-related increases in PPc and the variability of PPc across the adult lifespan in communities with a high prevalence of uncontrolled hypertension; that P1 contributes substantially to the relationship between PPc and LVMI; and that PPc and both the AP and P1 component pressures are associated with a urinary index of salt intake as well as genetic factors, but not to an index of low-grade inflammation. These findings suggest that to achieve optimal cardiovascular risk reduction in hypertension, therapeutic strategies that target the aortic structural changes responsible for P1 are likely to be required across the adult lifespan, and that this therapy must in-part address the impact of salt intake and genetic factors, but not necessarily low-grade inflammation on PPc.

Genome-wide association studies have revealed an association between variation at the SLC4A7 locus and blood pressure. SLC4A7 encodes the electroneutral Na+/HCO3 - co-transporter NBCn1 which regulates intracellular pH (pHi) in a range of tissues, including vascular smooth muscle and endothelium. Notably, the SLC4A7 knockout mouse has been shown to have an altered blood pressure phenotype. This thesis presents a functional study of variants at this locus in primary cultures of vascular smooth muscle and endothelial cells. There were genotype-dependent differences in DNA-nuclear protein interactions by formaldehyde-assisted isolation of regulatory elements, electrophoretic mobility shift assays and DNA pulldown assays. Subsequently, there were also genotypedependent differences in SLC4A7 expression level and NBCn1 availability at the plasma membrane. In turn, SLC4A7 genotype is associated with Na+/HCO3 --dependent steady-state pHi and recovery from intracellular acidosis. The genotypic effect on pHi regulation was independent of the calcineurin activity, or the amino acid substitution E326K resulting from a missense polymorphism. However, in the presence of Na+/H+ exchange activity, the SLC4A7 genotypic effect on net base uptake and steady-state pHi was detected only in vascular smooth muscle cells but not endothelial cells. The finding of a genotypic influence on SLC4A7 expression and pHi regulation in vascular smooth muscle cells provide an insight into the molecular mechanism underlying the association of variation at the SLC4A7 locus with blood pressure.

Gypsum has been used almost exclusively as the mould material for casting sanitary-ware due to its high versatility, strength and homogenous pore distribution. However gypsum moulds have a number of disadvantages including deterioration on contact with water, deformation, long set times and short mould lives such that a large number of moulds are required for a commercial manufacturing processes. These drawbacks have led to attempts to find a new synthetic material to create moulds with similar properties to gypsum with respect to fine homogeneous pores, but with increased durability. Porous PMMA was developed in 1971 for the purpose of moulding ceramics. The basic approach to making the materials has remained unchanged since its commercial introduction with few academic studies undertaken on the formulations. This thesis describes an investigation into porous PMMA from an academic perspective studying the mechanism of formation of the materials and the role of the components in polymerisation. In particular: the surfactant type and level, monomer type, water to monomer ratio and bead size have been probed to assess their effect on the porosity and mechanical strength. A particular importance has been placed on the commercial viability of formulations because gypsum is a relatively inexpensive material and, due to its versatility and ease of manufacture, is still used throughout the ceramics industry. To increase cost competitiveness through spreading the higher cost of the raw materials and capital investment, the mechanical strength of porous PMMA materials has to be significantly greater to increase the number of casting cycles from each mould. In addition, to achieve competitive advantage in the marketplace, a deep understanding of the formulation was undertaken. This should allow for tailoring of the mould properties allowing for specialised moulds for different applications. In addition, this focused approach facilitates cost-savings allowing for the minimum input of raw materials. The thesis is a comprehensive body of work which looks individually at the components assessing their effect on the properties of the final material. In addition, the formation mechanism of the materials has been explored by breaking down the polymerisation into key stages. Highlighted is the excessive use of surfactant in a commercial formulation and the influence of plasticisation of the ligaments by the surfactant and excess monomer. The theory behind the polymerisation process, which generates the ligaments and traps the polymer beads in an immobile matrix, is developed; forming a comprehensive understanding of the formation of porous PMMA materials and factors influencing their development and final properties.