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The catalytic transformation of polymer waste using modified clay catalystsTaylor, Scott January 2002 (has links)
A variety of modified minerals have been screened to determine their effectiveness as agents for the catalytic transformation of the thermally generated off gases arising from the pyrolysis of the polyolefinic plastic High Density Polyethylene (HDPE). This polymer has been shown to degrade through a series of known mechanisms to yield a hydrocarbon product mixture consisting of an homologous series of saturated and unsaturated hydrocarbons which include alk-1-enes, n-alkanes, alk-x-enes and a-w-dienes. Modification treatments have been wide ranging having included activation of the parent mineral by means of pillaring, ion exchange and acid activation. The activated products have been characterised by XRD, XRF, TGA and vibrational spectroscopy. Moreover, evolved gas analysis has been employed to perform catalytic screening runs on these modified minerals. In particular, attention has been paid to the activity of these materials in respect of the formation of potentially fuel applicable hydrocarbons, namely those exhibiting high octane ratings, including aromatics and branched aliphatics from the feedstock species present in the HDPE pyrolysate gas mixture. Pillared clays (PILC's) have proven ineffective in this role as a consequence of their poor reproducibility and lack of selectivity towards the formation of single ring aromatics. Likewise, ion exchange has been found to influence strongly the catalytic behaviour of previously acid activated clays, with autotransformed samples offering dehydrocyclisation (DHC) activity at levels significantly greater than seen with some ion exchanged samples, particularly protons. Acid activated metakaolinites have demonstrated poor selectivity in terms of aromatic formation, although total DHC activity is good. Metakaolin also gave rise to appreciable activity in respect of the formation of the single ring aromatics selected for monitoring in this work. Isomerisation activity was prevalent over these materials, but coking levels were high. Acid activated smectites represent the most suitable candidates to fulfil the role of single step fuel generation from the transformation of the gas stream resulting from HDPE pyrolysis. It has been found that careful control over the chemical and physical properties of acid activated clays can be achieved through consideration of the severity of the activation parameters chosen to induce modification. In addition, the nature of the activated product is strongly dependant on the nature of the base clay. In particular, acid activated beidellites have been shown to exhibit high levels of surface acidity as determined through the thermal desorption of cyclohexylamine. These materials consequently give rise to respectable activity and selectivity in terms of the formation of highly octane rated methyl substituted single ring aromatics, principally trimethylbenzene. In contrast, acid activated montmorillonites have been seen to offer lower levels of total surface acidity and have been shown to be active in promoting skeletal isomerisation reactions to yield branched aliphatics, again, highly octane rated. This activity variation has been attributed to the formation of highly Bronsted acidic silanol containing Surface Localised Acid Pools (SLAP's) on the exposed surfaces of the former as a consequence of the isomorphous substitution patterns observed in the tetrahedral sheets of beidellites.
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Modeling, design, fabrication and demonstration of multilayered ferromagnetic polymer-dielectric composites for ultra-thin high-denisty power inductorsMishra, Dibyajat 07 January 2016 (has links)
The emerging need for smart and wearable electronic systems are driving new
electronics technology paradigms in miniaturization, functionality and
cost.The operating voltages and power levels for devices in these systems
are becoming increasingly varied with increased diversity of devices to
serve these heterogeneous functions. Power convertor technologies are
incorporated into various parts of these systems to step-up or step-down
battery voltages and currents to address these diverse needs. Hence,
multiple power converters, each requiring several passive components, are
used to create stable power-supplies. This is placing significant challenges
in ultra-miniaturized and ultra-efficient power management technologies.
A typical power convertor consists of magnetic components such as inductors
perform the basic energy storage and delivery functions from the source to
the load. These power components are still at microscale in lithography and
milliscale in component size. They occupy a large volume fraction of the
power circuitry. Power convertors therefore, are a major bottleneck to
system miniaturization. There is, thus, a need for ultra-miniaturized and
high-performance power inductors for scaling down such power convertors. The
critical parameters governing the size and performance of power inductors
are its inductance density and power handling capability. These parameters
are limited by the magnetic properties of the present inductor core
materials. A new approach to inductor cores that achieves the best magnetic
properties and yet allows integration of power inductors into ultra-thin
substrates to meet the emerging needs for performance and size is therefore
required.
The objective of this research is to model, design and synthesize a novel
multilayered ferromagnetic-polymer composite structure for inductor cores
with high permeability and saturation magnetization.The multilayered
composite structure consists of thin magnetic layers interspersed with
ultra-thin polymers. A fabrication approach to integrate the composite
structure in inductor devices is also demonstrated.
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Genetic contributors to high density lipoprotein cholesterol levelsSlatter, Tania Lee, n/a January 2007 (has links)
Reduced high-density lipoprotein cholesterol (HDL-C) concentrations are a major risk factor for cardiovascular disease. Intense interest recently has been in identifying the genetic factors that contribute to an aberrant HDL-C phenotype. Finding genetic factors associated with low HDL-C concentrations in New Zealanders was the major aim of this study, with a similar analysis aimed at finding factors associated with high HDL-C concentrations included. The study began with an investigation of a New Zealand family with HDL-C deficiency. The proband had virtually no HDL-C, and was homozygous for an R1068H mutation in the ABCA1 gene. Nineteen relatives were recruited into the study, and an analysis aimed at finding the underlying cause for the disparate HDL-C phenotypes amongst H1068 carriers initiated.
A further investigation into HDL-C levels aimed to find other genetic factors that contribute to HDL-C in New Zealanders. Subjects were selected from those taking part in the Otago Vascular Disease study, and placed into three groups based on their HDL-C lipid measurement: low (n=154), mid (n=105), and high (n=102) HDL-C. Mutations in ABCAI and the apolipoprotein AI gene (APOAI) were identified in subjects with low HDL-C. Polymorphisms in ABCA1 and APOAI were also investigated as contributors to HDL-C concentrations. Seventeen SNPs in functionally relevant regions were genotyped in the three HDL-C groups. Five single polymorphisms and one polymorphism haplotype showed a statistically significant association with HDL-C concentrations.
The final analysis investigated plasma lipoprotein compositions in individuals with low HDL-C to identify if other lipoprotein abnormalities concurred. Individuals with HDL-C below 0.65 mmol/L were almost invariably associated with triglyceride-rich VLDL and/or triglyceride-rich LDL. This finding may have relevance for an increased atherosclerotic risk for those with low HDL-C.
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The role of anti-inflammatory properties of high density lipoproteins in atheroprotection / by Stephen James Nicholls.Nicholls, Stephen James January 2004 (has links)
"September 2004" / Bibliography: leaves 236-262. / xxxi, 262 leaves : ill., plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2004
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Density ReconsideredLyu, Jiayue 19 January 2022 (has links)
The work seeks to reconsider aspects of high density in urban architecture, exemplified in a site in Hong Kong, where currently urban housing, temple, commercial, office and other structures coexist. While a very high density of urban housing is in place, it does not consider qualities of living such as natural light and view in the apartment layouts. In addition to qualities directly related to living, the thesis also seeks to engage a notion of identity and individuality which is often absent in high density projects. The stereotypical image of mediocre high-density environments is a relentless repetition of stacked units which accommodates only very basic human needs of cooking and sleeping but does not offer high quality urban spaces where people can expand their otherwise tight dwelling.
The investigation seeks to recognize the particularities of the Hong Kong site, including a temple complex which offers itself as a unique and peaceful moment, contrary to the hustle and bustle of the city. The relationship between dwellings and temple is a point of departure which architecturally expresses a deep respect for culture and context of Hong Kong.
A good architectural density in this sense is a composite of diverse function and spaces that offer opportunities of activities that together form a sense of place. / Master of Architecture / This thesis explores what a reconsidered density in a city could benefit the immediate environment and offer a better living quality for the residents.
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LIPOPROTEIN RECEPTORS IN COPPER-DEFICIENT RATS: IN VITRO BINDING OF HIGH DENSITY LIPOPROTEIN SUBFRACTIONS TO LIVER MEMBRANES.Hassel, Craig Alan January 1986 (has links)
Three studies were conducted to determine whether the elevated plasma and HDL cholesterol levels observed in copper-deficient rats could be explained by the interaction of ¹²⁵I-HDL subfractions with liver membrane preparations in vitro. Rats from all studies were randomly divided into two dietary treatments, copper-deficient and adequate (0.7 mg and 8.0 mg Cu/kg diet, respectively). Deionized water and diet were provided ad libitum. After eight weeks, rats were exsanguinated, membranes prepared from livers, and plasma high density lipoproteins (HDL) isolated by ultracentrifugation and agarose column chromatography. Heparin-Sepharose affinity chromatography was used to isolate specific subfractions of HDL. The HDL subfractions derived from rats of each dietary treatment were iodinated and bound to either crude liver membranes or purified liver plasma membranes prepared from rats of both treatment groups. Total binding data and computer derived estimates (K(d) and B(max)) were used to compare differences between treatments. Binding data from all experiments conformed to a one-site model. In all cases, binding was saturable and EDTA and pronase insensitive. Treatment differences were observed in Study I (¹²⁵I-apo E-free HDL binding to crude liver membranes). Significantly lower total binding and B(max) were observed when lipoproteins and membranes from copper-deficient animals were used in the assay. Competition experiments from Studies II and III demonstrate that the different HDL subfractions competed effectively with one another for binding sites, indicating that apo E is not a determinant in binding of rat ¹²⁵I-HDL subfractions to purified liver plasma membranes.
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The investigation of diffractive optics systems and their applicationsYang, Guoguang January 2000 (has links)
No description available.
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Could androgens or zinc underlie the role of HDL-cholesterol in cardiovascular disease : a reviewNg, Waai-yan, Tiffany, 伍尉慇 January 2013 (has links)
Background
Over the past few years, results refuting the causal role of HDL cholesterol (HDL-c) have been reported by a number of randomized controlled trials (RCTs) testing different ways of modifying HDL-c. Results from Mendelian randomization studies showed no difference in cardiovascular disease (CVD) risk among individuals with genetically different serum levels of HDL-c. The causal role of HDL-c in CVD is thus uncertain, raising the question as to whether HDL-c is a worthwhile target of public health interventions and medical treatments. The objective of these meta-analyses is to explore whether changes in HDL-c are symptomatic of prior causes instead of being a causal factor for CVD by first identifying two possible candidates—androgens and zinc—for the investigation of associations. Experimental evidence would then be investigated for whether either of them might underlie (i.e. confound) the observed association of HDL-c with CVD risk factors.
Methods
This study followed the PRISMA statement. A literature search was conducted through PUBMED, MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials. Keywords of “androgens/testosterone”, “HDL”, “high-density lipoprotein”, “lipid”, “cholesterol”, “lipoprotein”, “CVD”, “cardiovascular”, “heart”, “cardiovascular disease” were used with the search period limited to January 2000 – June 2013 with only human RCTs conducted and reported in English. For locating studies concerning the effect of zinc, the keyword “zinc” was used instead of “androgens/testosterone”.
Inclusion and exclusion criteria were applied during study screening and selection. The Cochrane Collaboration’s tool for assessing risk of bias was used for quality assessment. Heterogeneity across included studies was measured using I2 statistic and publication bias was assessed via funnel plots and the Begg’s Rank Correlation test. The “trim and fill” method was also used for the correction of funnel plot asymmetry.
The meta-analyses were performed using The Comprehensive R Archive Network Program (Version R 3.0.0), using the function “metacont” from the “meta” package, where the pooled intervention effects were displayed using forest plots, with inverse variance weighting and random effects model.
Results
A total of twelve and ten RCTs were identified and included in the meta-analyses of androgens and zinc respectively. There were no consistent beneficial effects of androgens on CVD observed, as the results from CVD surrogate markers were inconclusive, despite showing significant overall reduction in HDL-c levels. However, as current findings suggest that lower HDL-c levels are associated with higher cardiovascular risk, it is possible that androgens may increase that risk by influencing HDL metabolism.
On the other hand, zinc was associated with healthier CVD profile. This supports the notion of zinc as a cardioprotective agent. Nonetheless, conclusion failed to be drawn concerning the effect of zinc on HDL-c as there were contradictory results across included studies.
Conclusion
The meta-analyses suggest that androgens could be a factor which lowers HDL-c and thus increases cardiovascular risk, rather than HDL-c being the direct causative agent. This research may serve as a template for more extensive search for other potentially better candidates in this new study focus in cardiovascular epidemiology. / published_or_final_version / Community Medicine / Master / Master of Public Health
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Physical activity and high -density lipoprotein cholesterol in sedentary male smokersShaw, BS, Shaw, I 16 December 2007 (has links)
High-density lipoprotein (HDL) with its cardio-
protective effects has provided remarkable
optimism to the ever-increasing incidences of
coronary artery disease. Therefore, the aim of this
randomized, comparative, research trial was to
determine whether endurance exercise training,
weight training and/or a combination of aerobic and
weight training can be utilized in the management
of high-density lipoprotein cholesterol (HDL-C).
Subsequent to the 16-week intervention period,
dependant t-Tests revealed that the non-exercising
and weight training groups demonstrated non-
significant mean 1.3% (p = 0.754) and 11.1% (p =
0.069) increases in fasting serum HDL-C,
respectively. Conversely, there was a significant
increase in HDL-C following the 16 weeks of
endurance training (p = 0.003) and combination
training (p = 0.005) (22.4% and 37.9%,
respectively). Further, Spearman’s rho indicated no
correlations between HDL-C and BMI (r = -0.131),
percentage body fat (r = - 0.141), cholesterol intake
(r = - 0.026) and total fat intake (r = - 0.239). The
absence of changes in these inter-correlations
indicated that changes in these parameters had no
effect on the HDL-C. On the contrary, moderate
correlations were established between HDL-C and
number of cigarettes smoked daily (r = - 0.344) and
intake of saturated fat (r = - 0.317) indicating that
exercise effect on these variables could have
indirectly contributed significantly in altering HDL-
C in the endurance and combination training
groups. As such, endurance and combination
training can be utilized as an effective method in the
management of HDL-C in sedentary male smokers.
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Remodelling of high density lipoproteins by plasma factors / by Hui-Qi Liang.Liang, Hui-Qi January 1996 (has links)
Bibliography: leaves 105-151. / xi, 151, [47] leaves, [3] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the effect of remodelling HDL on the metabolism of apo A-I. The major focus is on the effects of CETP and LCAT in the regulation of apo A-I concentration in DHL. The effects of incubation of HDL with CETP in the presence of VLDL and/or LDL on apo A-I concentration in HDL are examined. The characterization of the dissociated apo A-I from HDL is presented. The studies demonstrate that the dissociation of apo A-I from HDL mediated by CETP is preventable and reversible in a process dependent on LCAT activity. The mechanism by which HDL apo A-I content is increased is also explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1997?
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