Mechanical testing of natural fibre reinforced polyester resin composites and Mode 1 fracture toughness testing of resin blocks

Recent European Parliament directive requires companies to achieve materials recycling greater than 80% in particular in the automotive sector [1]. The research on natural fibre based composite materials fits well into this ecological image. The advantages of natural fibres over synthetic materials include, low density, relative cheapness, availability and biodegradability. In this paper we explore the fabrication and mechanical testing of natural fibre composites and this is part of an on going study at Strathclyde University and describes the fabrication of composites using natural fibre and styrene polyester resin. The properties of the synthetic resin can be varied by changing the catalysts concentration and flexural (three point bending) and single-edged notched bending (SENB) properties are reported at different concentrations of the catalyst

The effect of alkalisation on the mechanical properties of natural fibres

A study on the effect of alkalisaton using 3% NaOH solution was carried out on Flax, Kenaf, Abaca and Sisal to observe the impact that the common pre-treatment process has on fibre mechanical properties. The result of the investigation indicated that over-treatment of natural fibres using NaOH could have a negative effect on the base fibre properties. It is concluded that a treatment time of less than 10 minutes is sufficient to remove hemicelluloses and to give the optimum effect

Vacuum infusion of natural fibre composites for structural applications

Numerous methods of manufacturing natural fibre composites have been reported in the literature, including compression moudling, often in conjunction with a hot press. Other forms of composite manufacture include 'Vacuum Assisted Resin Transfer Moulding' (VATRM) and the 'Seemann Composite Resin Infusion Moulding Process' (SCRIMP). These methods have been reported to produce natural fibre composies with reasonable mechanical properties [1-2]. In this paper, a vacuum infusion rig is described that has been developed to produce consistent quality composite plates for studies into optimising natural fibre composites. The process aims to harness the benefits of vacuum infusion and compression moulding, where vacuum infusion encourages the removal of trapped air in the system and hence avoid reduction, and additional compression moulding can help to achieve high volume fractions that are otherwise difficult in other processes

Qualitatively modelling genetic regulatory networks : Petri net techniques and tools

The development of post-genomic technologies has led to a paradigm shift in the way we study genetic regulatory networks (GRNs) - the underlying systems which mediate cell function. To complement this, the focus is on devising scalable, unambiguous and automated formal techniques for holistically modelling and analysing these complex systems. Quantitative approaches offer one possible solution, but do not appear to be commensurate with currently available data. This motivates qualitative approaches such as Boolean networks (BNs) , which abstractly model the system without requiring such a high level of data completeness. Qualitative approaches enable fundamental dynamical properties to be studied, and are well-suited to initial investigations. However, strengthened formal techniques and tool support are required if they are to meet the demands of the biological community. This thesis aims to investigate, develop and evaluate the application of Petri nets (PNs) for qualitatively modelling and analysing GRNs. PNs are well-established in the field of computer science, and enjoy a number of attractive benefits, such a wide range of techniques and tools, which make them ideal for studying biological systems. We take an existing qualitative PN approach for modelling GRNs based on BNs, and extend it to more general models based on multi-valued networks (MVNs). Importantly, we develop tool support to automate model construction. We illustrate our approach with two detailed case studies on Boolean models for carbon stress in Escherichia coli and sporulation in Bacillus subtilis, and then consider a multi-valued model of the former. These case studies explore the analysis power of PN s by exploiting a range of techniques and tools. A number of behavioural differences are identified between the two E. coli models which lead us to question their formal relationship. We investigate this by proposing a framework for reasoning about the behaviour of MVNs at different levels of abstraction. We develop tool support for practical models, and show a number of important results which motivate the need for multi-valued modelling. Asynchronous BN s can be seen to be more biologically realistic than their synchronous counterparts. However, they have the drawback of capturing behaviour which is unrealisable in practice. We propose a novel approach for refining such behaviour using signal transition graphs, a PN formalism from asynchronous circuit design. We automate our approach, and demonstrate it using a BN of the lysis-lysogeny switch in phage A. Our results show that a more realistic asynchronous model can be derived which preserves the stochastic switch.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

High temperature radiator materials for applications in the low Earth orbital environment

Radiators must be constructed of materials which have high emittance in order to efficiently radiate heat from high temperature space power systems. In addition, if these radiators are to be used for applications in the low Earth orbital environment, they must not be detrimentally affected by exposure to atomic oxygen. Four materials selected as candidate radiator materials (304 stainless steel, copper, titanium-6% aluminum-4% vanadium (Ti-6%Al-4%V), and niobium-1% zirconium (Nb-1%Zr)) were surface modified by acid etching, heat treating, abrading, sputter texturing, electrochemical etching, and combinations of the above in order to improve their emittance. Combination treatment techniques with heat treating as the second treatment provided about a factor of two improvement in emittance for 304 stainless steel, Ti-6%Al-4%V, and Nb-1%Zr. A factor of three improvement in emittance occurred for discharge chamber sputter textured copper. Exposure to atomic oxygen in an RF plasma asher did not significantly change the emittance of those samples that had been heat treated as part of their texturing process. An evaluation of oxygen penetration is needed to understand how oxidation affects the mechanical properties of these materials when heat treated

Detection rate of actionable mutations in diverse cancers using a biopsy-free (blood) circulating tumor cell DNA assay.

Analysis of cell-free DNA using next-generation sequencing (NGS) is a powerful tool for the detection/monitoring of alterations present in circulating tumor DNA (ctDNA). Plasma extracted from 171 patients with a variety of cancers was analyzed for ctDNA (54 genes and copy number variants (CNVs) in three genes (EGFR, ERBB2 and MET)). The most represented cancers were lung (23%), breast (23%), and glioblastoma (19%). Ninety-nine patients (58%) had at least one detectable alteration. The most frequent alterations were TP53 (29.8%), followed by EGFR (17.5%), MET (10.5%), PIK3CA (7%), and NOTCH1 (5.8%). In contrast, of 222 healthy volunteers, only one had an aberration (TP53). Ninety patients with non-brain tumors had a discernible aberration (65% of 138 patients; in 70% of non-brain tumor patients with an alteration, the anomaly was potentially actionable). Interestingly, nine of 33 patients (27%) with glioblastoma had an alteration (6/33 (18%) potentially actionable). Overall, sixty-nine patients had potentially actionable alterations (40% of total; 69.7% of patients (69/99) with alterations); 68 patients (40% of total; 69% of patients with alterations), by a Food and Drug Administration (FDA) approved drug. In summary, 65% of diverse cancers (as well as 27% of glioblastomas) had detectable ctDNA aberration(s), with the majority theoretically actionable by an approved agent

Hypothesis-based Restoration Study For Mitigation of a Damaged SE Florida Coral Reef: A Work in Progress

The United States Submarine Memphis (Figure 1) ran aground in approximately 10 meter depth on a coral reef off southeast Florida (Figure 2) February 25, 1993. Extensive physical damage to the reef substrate and injury to the coral community were attributed to the initial grounding and subsequent attempts to free the submarine from the impacted reef (Figures 3 and 4). The impact of the grounding was assessed, and the area of damage was determined through field and photographic studies. An impacted area of 2,310 m2 was assessed with 1,205 m2 having been totally destroyed (Figures 3 and 4). In 1997, the State of Florida was awarded a settlement of $750,000 by the Federal government for environmental damages caused by the submarine grounding. A plan to perform hypothesis testing of restoration techniques was developed and initiated. Using artificial reefs as experimental platforms, we are examining three restoration strategies: 1) the potential of enhancing coral recruitment through the use of coral larval attractants, 2) the effect of reef structure on the associated fish assemblages, and 3) the interaction between fish assemblages and coral recruitment and survival

Coral of Opportunity Survivorship and the Use of Coral Nurseries in Coral Reef Restoration

Coral reef damage is unfortunately becoming a common occurrence off southeast Florida, U.S.A. Reattachment of the dislodged scleractinian corals usually initiates damage site restoration. Because mortality of dislodged colonies is typically high and natural recovery in southeast Florida is typically slow, transplantation of additional scleractinian corals into a damaged area has been used to accelerate reef recovery. Donor colonies available for transplantation have been grown in situ, grown in laboratories, and taken from nondamaged reef areas. An alternative source of donor colonies for transplantation into damaged sites is “corals of opportunity,” which we define as scleractinian corals that have been detached from the reef through natural processes or unknown events. This paper describes a project, initiated in 2001 in Broward County, Florida, that was developed to collect these dislodged colonies and transplant them to a coral nursery. Coral nurseries are interim locations that function as storage sites for corals of opportunity where they can be cached, stabilized, and allowed to grow, until needed as donor colonies for future restoration activities. This project is a partnership between a local university, county government, and a volunteer dive group. Two hundred and fifty corals of opportunity were collected, transplanted to the coral nurseries, and monitored for survival. Transplanted colony survival was similar to that of naturally attached control colonies and significantly greater than that of corals of opportunity left unattached. Results provide resource managers with information on the utility of using corals of opportunity as a source of transplant donor colonies, and the value of using coral nurseries to create a reserve of corals of opportunity for use in future coral reef restoration activities

Lithium isotopes in fluid inclusions as tracers of crustal fluids: An exploratory study

Lithium isotopes are extensively used to trace fluid migration and fluid-rock interactions in the shallow Earth's crust. Although, Li isotope systematics might give important information about deep crustal fluids, this stable isotope system remains surprisingly under exploited in fluid inclusions. Here, twenty-three samples from a variety of deep environments, from diagenetic, metamorphic to magmatic-hydrothermal conditions (~150 to 600°C), have been investigated in order to provide the first exploratory overview of the range in Li isotopic composition of fluid inclusions. From 1 to 2g of hydrothermal quartz or dolomite, cation analysis (Na, K, Ca, Mg, Sr, Li), Li fraction recovery and Li isotopic analysis of bulk fluid inclusion leachates were carried out by using an innovative approach coupling crush-leach extraction, high performance ion chromatography and MC-ICPMS analysis. Reconstructed Li concentrations and δ7Li values of these fluid inclusions (respectively 12 to 653mg/l and −1.4±0.2‰ to +41.3±0.8‰) are compatible with previously proposed models for the origin of the fluids and fluid-rock interactions. δ7Li values are independent from other tracers (Br/Cl, I/Cl) and parameters such as temperature, salinity, and cation content (Na/Ca, Na/K, Na/Mg, Na/Li, Na/Sr ratios). The results show that, in conjunction with other parameters, the Li isotopic compositions of fluid inclusions are potentially powerful source and process tracers of deep crustal fluids within a wide range of geological environments and related ore-forming systems, for example in from sedimentary basins, seafloor hydrothermal systems and subduction zones