An eigenfunction expansion-variational method in prediction of the transverse thermal conductivity of fiber reinforced composites considering interfacial characteristics

An eigenfunction expansion-variational method based on a unit cell is developed to deal with the steady-state heat conduction problem of doubly-periodic fiber reinforced composites with interfacial thermal contact resistance or coating. The numerical results show a rapid convergence of the present method. The present solution provides a unified first-order approximation formula of the effective thermal conductivity for different interfacial characteristics and fiber distributions. A comparison with the present high-order results, available experimental data and micromechanical estimations demonstrates that the first-order approximation formula is a good engineering closed-form formula. An engineering equivalent parameter reflecting the overall influence of the thermal conductivities of the matrix and fibers and the interfacial characteristic on the effective thermal conductivity, is found. The equivalent parameter can greatly simplify the complicated relation of the effective thermal conductivity to the internal structure of a composite. (c) 2010 Elsevier Ltd. All rights reserved.

Unified expressions of all integral variational principles

In terms of the quantitative causal principle, this paper obtains a general variational principle, gives unified expressions of the general, Hamilton, Voss, Holder, Maupertuis-Lagrange variational principles of integral style, the invariant quantities of the general, Voss, Holder, Maupertuis-Lagrange variational principles are given, finally the Noether conservation charges of the general, Voss, Holder, Maupertuis-Lagrange variational principles axe deduced, and the intrinsic relations among the invariant quantities and the Noether conservation charges of all the integral variational principles axe achieved.

Synthesis and characterisation of novel imidazolium-based ionic liquid crystals with a p-nitroazobenzene moiety

A novel series of compounds with different counter anions, i.e. 1-{[4-(4-nitrophenylazo)phenyloxy]}alkyl-3-methyl-1H-imidazol-3-ium bromide salts (C-n , n=3, 6, 10) and tetrafluoroborate salts (D-n , n=3, 6, 10), were synthesised by the incorporation of an imidazolium group into paraffin side chain-terminated 4-nitroazobenzene derivatives. Their chemical structures were determined by H-1 NMR, C-13 NMR, UV spectroscopy and elemental analysis.

Synthesis and characterisation of novel functional polyolefin containing sulfonic acid groups

The strong polar group, sulfonic acid, has successfully been introduced into ethylene/allylbenzene copolymers without degradation or crosslinking via chlorosulfonation reaction with chlorosulfonic acid as a chlorosulforiating agent in 1, 1,2,2-tetrachloroethane followed by hydrolysis. The degree of sulforiation (DS) can be easily controlled by changing the ratio of chlorosulfonic acid to the pendant phenyls of the copolymer. The microstructure of sulfonated copolymers were unambiguously revealed by H-1 NMR and H-1-H-1 COSY spectral analyses, which indicates that all the sulforiation reactions exclusively took place at the para-position of the aromatic rings.

Synthesis, characterisation and catalytic activity of propionamide complexes of rare earth chlorides

Propionamide complexes of rare earth chlorides were synthesized, Formula of the complexes is LnCl(3). 3BA. The ligand is shown to behave as a normal amide donor With the oxygen of the carbonyl group coordinated to the metal ions. Binary system composed Elf propionamide and aluminum alkyl shows higher activity and stereospecificity for butadiene polymerization. The cis-1,4 content of polybutadiene is more than 98%.

Molecular cloning and characterisation of prophenoloxidase (ProPO) cDNA from Fenneropenaeus chinensis and its transcription injected by Vibrio anguillarum

The prophenoloxidase(ProPO) gene was cloned from haemocytes of Chinese shrimp Fenneropenaeus chinensis by Rapid Amplification Complementary DNA Ends (RACE) method. The full-length cDNA of prophenoloxidase gene consists of 3040 bp with a 2061 bp Open Reading Frame (ORF), encoding 686 amino acids. Phylogenetic analysis revealed that it belongs to insect-type invertebrate prophenoloxidase gene family. To understand ProPO reaction for pathogeny's challenge in shrimp, the expressions of ProPO in different tissues were studied by real-time PCR after challenged by Vibrio anguillarum. The results showed that the expression level of ProPO gene in haemocytes was highest among three studied tissues including haemocytes, lymphoid organ and hepatopancreas. The time-course change of ProPO mRNA levels in challenge experiment showed that ProPO mRNA transcripts had the biggest change extent in lymphoid organ.

Molecular cloning and characterisation of a pattern recognition protein, lipopolysaccharide and beta-1,3-glucan binding protein (LGBP) from Chinese shrimp Fenneropenaeus chinensis

A pattern recognition protein (PRP), lipopolysaccharide and beta-1,3-glucan binding protein (LGBP) cDNA was cloned from the haemocyte of Chinese shrimp Fenneropenaeus chinensis by the techniques of homology cloning and RACE. Analysis of nucleotide sequence revealed that the full-length cDNA of 1,275 bp has an open reading frame of 1,098 bp encoding a protein of 366 amino acids including a 17 amino acid signal peptide. Sequence comparison of the deduced amino acid sequence of F. chinensis LGBP showed a high identity of 94%, 90%, 87%, 72% and 63% with Penaeus monodon BGBP, Litopenaeus stylirostris LGBP, Marsupenaeu japonicus BGBP, Homarus gammarus BGBP and Pacifastacus leniusculus LGBP, respectively. The calculated molecular mass of the mature protein is 39,857 Da with a deduced pI of 4.39. Two putative integrin binding motifs, RGD (Arg-Gly-Asp) and a potential recognition motif for beta-1,3-linkage of polysaccharides were observed in LGBP sequence. RT-PCR analysis showed that LGBP gene expresses in haemocyte and hepatopancreas only, but not in other tissues. Capillary electrophoresis RT-PCR method was used to quantify the variation of mRNA transcription level during artificial infection with heat-killed Vibrio anguillarum and Staphylococcus aureusin. A significant enhancement of LGBP transcription was appeared at 6 h post-injection in response to bacterial infection. These results have provided useful information to understand the function of LGBP in shrimp.

A key gene of the RNA interference pathway in the black tiger shrimp, Penaeus monodon: Identification and functional characterisation of Dicer-1

RNA interference (RNAi) is an evolutionarily conserved mechanism by which double-stranded RNA (dsRNA) initiates post-transcriptional silencing of homologous genes. Here we report the amplification and characterisation of a full length cDNA from black tiger shrimp (Penaeus monodon) that encodes the bidentate RNAase III Dicer, a key component of the RNAi pathway. The full length of the shrimp Dicer (Pm Dcr1) cDNA is 7629 bp in length, including a 51 untranslated region (UTR) of 130 bp, a 3' UTR of 77 bp, and an open reading frame of 7422 bp encoding a polypeptide of 2473 amino acids with an estimated molecular mass of 277.895 kDa and a predicted isoelectric point of 4.86. Analysis of the deduced amino acid sequence indicated that the mature peptide contains all the seven recognised functional domains and is most similar to the mosquito (Aedes aegypti) Dicer-1 sequence with a similarity of 34.6%. Quantitative RT-PCR analysis showed that Pm Dcr1 mRNA is most highly expressed in haemolymph and lymphoid organ tissues (P 0.05). However, there was no correlation between Pm Dcr1 mRNA levels in lymphoid organ and the viral genetic loads in shrimp naturally infected with gill-associated virus (GAV) and Mourilyan virus (P > 0.05). Treatment with synthetic dsRNA corresponding to Pm Dcr1 sequence resulted in knock-down of Pm Dcr1 mRNA expression in both uninfected shrimp and shrimp infected experimentally with GAV. Knock-down of Pm Dcr1 expression resulted in more rapid mortalities and higher viral loads. These data demonstrated that Dicer is involved in antiviral defence in shrimp. (c) 2007 Elsevier Ltd. All rights reserved.

Purification and characterisation of a natural lectin from the serum of the shrimp Litopenaeus vannamei

A natural lectin from the serum of the shrimp Litopenaeus vannamei was purified to homogeneity by a single-step affinity chromatography using fetuin-coupled agarose. The purified serum lectin (named LVL) showed a strong affinity for human A/B/O erythrocytes (RBC), mouse RBC, chicken RBC and its haemagglutinating (HA) activity was specifically dependent on Ca2+ and reversibly sensitive to EDTA. LVL inactive form had a molecular mass estimate of 172 kDa and was composed of two non-identical subunits (32 and 38 kDa) cross-linked by interchain disulphide bonds. Significant LVL activity was observed between pH 7 and 11. In HA-inhibition assays performed with several carbohydrates and glycoproteins, LVL showed a distinct and unique specificity for GalNAc/GluNAc/NeuAc which had an acetyl group, while glycoproteins fetuin and bovine submaxillary mucin (BSM) had sialic acid. Moreover, this agglutinin appeared to recognise the terminal N- and O-acetyl groups in the oligosaccharide chain of glycoconjugates. The HA activity of L. vannamei lectin was also susceptible to inhibition by lipopolysaccharides from diverse Gram-negative bacteria, which might indicate a significant in vivo role of this humoral agglutinin in the host immune response against bacterial infections. (C) 2006 Elsevier Ltd. All rights reserved.

Small angle scattering characterisation of micellar systems and templated architectures

The work described in this thesis reports the structural changes induced on micelles under a variety of conditions. The micelles of a liquid crystal film and dilute solutions of micelles were subjected to high pressure CO2 and selected hydrocarbon environments. Using small angle neutron scattering (SANS) techniques the spacing between liquid crystal micelles was measured in-situ. The liquid crystals studied were templated from different surfactants with varying structural characteristics. Micelles of a dilute surfactant solution were also subjected to elevated pressures of varying gas atmospheres. Detailed modelling of the in-situ SANS experiments revealed information of the size and shape of the micelles at a number of different pressures. Also reported in this thesis is the characterisation of mesoporous materials in the confined channels of larger porous materials. Periodic mesoporous organosilicas (PMOs) were synthesised within the channels of anodic alumina membranes (AAM) under different conditions, including drying rates and precursor concentrations. In-situ small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) was used to determine the pore morphology of the PMO within the AAM channels. PMO materials were also used as templates in the deposition of gold nanoparticles and subsequently used in the synthesis of germanium nanostructures. Polymer thin films were also employed as templates for the directed deposition of gold nanoparticles which were again used as seeds for the production of germanium nanostructures. A supercritical CO2 (sc-CO2) technique was successfully used during the production of the germanium nanostructures.

Precision biomechanical motion tracking and throw characterisation in professional darts

In professional sports there are in general three steps required to improve performance namely task definition, training and performance assessment. This process is iteratively repeated and feedback generated from quantitative performance measurement is in turn used for task redefinition. Task definition can be achieved in a number of ways including via video streaming or indeed and as is more common, by listening to coaching staff. However non-subjective performance evaluation is difficult due to the complexity of the movements involved. When considering the subset of sports where precision accuracy and repeatability are a necessity this problem becomes inherently more difficult to solve. Until recently sports such as martial arts, fencing and darts, where the smallest deviation from a prescribed movement goal can result in large outcome error, were deemed too difficult to characterise fully. Advances in technology, as illustrated by this study, now make this type of physiometry possible.

The identification and characterisation of Rab4 interacting proteins

Rab4 is a member of the Rab superfamily of small GTPases. It is localized to the early sorting endosome and plays a role in regulating the transport from this compartment to the recycling and degradative pathways. In order to further our understanding of the role Rab4 plays in endocytosis, a yeast two-hybrid screen was performed to identify putative Rab4 effectors. A constitutively active mutant of Rab4, Rab4Q67L, when used as bait to screen a HeLa cDNA library, identified a novel 80kDa protein that interacted with Rab4-GTP. This protein was called Rab Coupling Protein (RCP). RCP interacts preferentially with the GTP-bound form of Rab4. Subsequent work demonstrated that RCP also interacts with Rab11, and that this interaction is not nucleotide-depenedent. RCP is predominantly membrane-bound and localised to the perinuclear recycling compartment. Expression of a truncation mutant of RCP, that contains the Rab binding domain, in HeLa cells, results in the formation of an extensive tubular network that can be labelled with transferrin. These tubules are derived from the recycling compartment since they are inaccessible to transferrin when the ligand is internalised at 18oC. The truncation mutant-induced morphology can be rescued by overexpression of active Rab11, but not active Rab4. This suggests that RCP functions between Rab4 and Rab11 in the receptor recycling pathway, and may act as a ‘molecular bridge’ between these two sequentially acting small GTPases. Quantitative assays demonstrated that overexpression of the truncation mutant results in a dramatic inhibition in the rate of receptor recycling. Database analysis revealed that RCP belongs to a family of Rab interacting proteins, each characterised by a carboxy-terminal coiled-coil domain and an amino-terminal phospholipid-binding domain. KIAA0941, an RCP homologue, interacts with Rab11, but not with Rab4. Overexpression of its Rab binding domain also results in a tubular network, however, this tubulation cannot be rescued by active Rab11.

Molecular characterisation of the mechanisms of compatible solute accumulation in Listeria monocytogenes

The ability of the Gram-positive foodborne pathogen Listeria monocytogenes to survive and grow in environments of elevated osmolarity can be attributed, at least in part, to the accumulation of a restricted range of low molecular mass solutes compatible with cellular function. Accumulated to high internal concentrations in hyper-saline environments, compatible solutes, either transported into the cell or synthesized de novo, play a dual role: helping to stabilize protein structure and function while also counterbalancing external osmotic strength, thus preventing water loss from the cell and plasmolysis. While previous physiological investigations identified glycine betaine, carnitine, and proline as the principal compatible solutes in the listerial osmostress response, genetic alanysis of the uptake/synthesis systems governing the accumulation of these compounds has, until now, remained largely unexplored. Representing the first genetic analysis of compatible solute accumulation in L. monocytogenes, this thesis describes the molecular characterization of BetL; a highly specific secondary glycine betaine transport system, OpuC; a multicomponent carnitine/glycine betaine transporter, and finally proBA; a two-gene operon encoding the first two enzymes of the listerial proline piosynthesis pathway. In addition to their role in osmotolerance, the potential of each system in contributing to listerial pathogenesis was investigated. While mutations in each gene cluster exhibited dramatic reductions in listerial osmotolerance, OpuC- mutants were additionally shown to exhibit reduced virulence when admisistered via the oral route. This represents the first direct link between the salt stress response and virulence in L. monocytogenes.

Preparation and characterisation of ceria particles

Cerium dioxide (ceria) nanoparticles have been the subject of intense academic and industrial interest. Ceria has a host of applications but academic interest largely stems from their use in the modern automotive catalyst but it is also of interest because of many other application areas notably as the abrasive in chemical-mechanical planarisation of silicon substrates. Recently, ceria has been the focus of research investigating health effects of nanoparticles. Importantly, the role of non-stoichiometry in ceria nanoparticles is implicated in their biochemistry. Ceria has well understood non-stoichiometry based around the ease of formation of anion vacancies and these can form ordered superstructures based around the fluorite lattice structure exhibited by ceria. The anion vacancies are associated with localised or small polaron states formed by the electrons that remain after oxygen desorption. In simple terms these electrons combine with Ce4+ states to form Ce3+ states whose larger ionic radii is associated with a lattice expansion compared to stoichiometric CeO2. This is a very simplistic explanation and greater defect chemistry complexity is suggested by more recent work. Various authors have shown that vacancies are mobile and may result in vacancy clustering. Ceria nanoparticles are of particular interest because of the high activity and surface area of small particulates. The sensitivity of the cerium electronic band structure to environment would suggest that changes in the properties of ceria particles at nanoscale dimensions might be expected. Notably many authors report a lattice expansion with reducing particle size (largely confined to sub-10 nm particles). Most authors assign increased lattice dimensions to the presence of a surface stable Ce2O3 type layer at low nanoparticle dimensions. However, our understanding of oxide nanoparticles is limited and their full and quantitative characterisation offers serious challenges. In a series of chemical preparations by ourselves we see little evidence of a consistent model emerging to explain lattice parameter changes with nanoparticle size. Based on these results and a review of the literature it is worthwhile asking if a model of surface enhanced defect concentration is consistent with known cerium/cerium oxide chemistries, whether this is applicable to a range of different synthesis methods and if a more consistent description is possible. In Chapter one the science of cerium oxide is outlined including the crystal structure, defect chemistry and different oxidation states available. The uses and applications of cerium oxide are also discussed as well as modelling of the lattice parameter and the doping of the ceria lattice. Chapter two describes both the synthesis techniques and the analytical methods employed to execute this research. Chapter three focuses on high surface area ceria nano-particles and how these have been prepared using a citrate sol-gel precipitation method. Changes to the particle size have been made by calcining the ceria powders at different temperatures. X-ray diffraction methods were used to determine their lattice parameters. The particles sizes were also assessed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and BET, and, the lattice parameter was found to decrease with decreasing particle size. The results are discussed in light of the role played by surface tension effects. Chapter four describes the morphological and structural characterization of crystalline CeO2 nanoparticles prepared by forward and reverse precipitation techniques and compares these by powder x-ray diffraction (PXRD), nitrogen adsorption (BET) and high resolution transmission electron microscopy (HRTEM) analysis. The two routes give quite different materials although in both cases the products are essentially highly crystalline, dense particulates. It was found that the reverse precipitation technique gave the smallest crystallites with the narrowest size dispersion. This route also gave as-synthesised materials with higher surface areas. HRTEM confirmed the observations made from PXRD data and showed that the two methods resulted in quite different morphologies and surface chemistries. The forward route gives products with significantly greater densities of Ce3+ species compared to the reverse route. Data are explained using known precipitation chemistry and kinetic effects. Chapter five centres on the addition of terbia to ceria and has been investigated using XRD, XRF, XPS and TEM. Good solid solutions were formed across the entire composition range and there was no evidence for the formation of mixed phases or surface segregation over either the composition or temperature range investigated. Both Tb3+ and Tb4+ ions exist within the solution and the ratios of these cations are consistent with the addition of Tb8O15 to the fluorite ceria structure across a wide range of compositions. Local regions of anion vacancy ordering may be visible for small crystallites. There is no evidence of significant Ce3+ ion concentrations formed at the surface or in the bulk by the addition of terbia. The lattice parameter of these materials was seen to decrease with decreasing crystallite size. This is consistent with increased surface tension effects at small dimension. Chapter six reviews size related lattice parameter changes and surface defects in ceria nanocrystals. Ceria (CeO2) has many important applications, notably in catalysis. Many of its uses rely on generating nanodimensioned particles. Ceria has important redox chemistry where Ce4+ cations can be reversibly reduced to Ce3+ cations and associated anion vacancies. The significantly larger size of Ce3+ (compared with Ce4+) has been shown to result in lattice expansion. Many authors have observed lattice expansion in nanodimensioned crystals (nanocrystals), and these have been attributed to the presence of stabilized Ce3+ -anion vacancy combinations in these systems. Experimental results presented here show (i) that significant, but complex changes in the lattice parameter with size can occur in 2-500 nm crystallites, (ii) that there is a definitive relationship between defect chemistry and the lattice parameter in ceria nanocrystals, and (iii) that the stabilizing mechanism for the Ce3+ -anion vacancy defects at the surface of ceria nanocrystals is determined by the size, the surface status, and the analysis conditions. In this work, both lattice expansion and a more unusual lattice contraction in ultrafine nanocrystals are observed. The lattice deformations seen can be defined as a function of both the anion vacancy (hydroxyl) concentration in the nanocrystal and the intensity of the additional pressure imposed by the surface tension on the crystal. The expansion of lattice parameters in ceria nanocrystals is attributed to a number of factors, most notably, the presence of any hydroxyl moieties in the materials. Thus, a very careful understanding of the synthesis combined with characterization is required to understand the surface chemistry of ceria nanocrystals.

Characterisation of the non-muscle α-actinins

Actinins are cytoskeleton proteins that cross-link actin filaments. Evolution of the actinin family resulted in the formation of Ca++-insensitive muscle isoforms (actinin-2 and- 3) and Ca++-sensitive non-muscle isoforms (actinin-1 and -4) with regard to their actin-binding function. Despite high sequence similarity, unique properties have been ascribed to actinin-4 compared with actinin-1. Actinin-4 is the predominant isoform reported to be associated with the cancer phenotype. Actinin-4, but not actinin-1, is essential for normal glomerular function in the kidney and and is able to translocate to the nucleus to regulate transcription. To understand the molecular basis for such isoform-specific functions I have comprehensively compared these proteins in terms of localisation, migration, alternative splicing, actin-binding properties, heterodimer formation and molecular interactions for the first time. This work characterises a number of commercially available actinin antibodies and in doing so, identifies actinin-1, -2 and -4 isoform-specific antibodies that enabled studies of actinin expression and localisation. This work identifies the actinin rod domain as the predominant domain that influences actinin localisation however localisation is likely to be effected by the entire actinin protein. si-RNA- mediated knockdown of actinin-1 and -4 did not affect migration in a number of cell lines highlighting that migration may only require a fraction of total non-muscle actinin levels. This work finds that the Ca++-insensitive variant of actinin-4 is expressed only in the nervous system and thus cannot be regarded as a smooth muscle isoform, as is the case for the Ca++-insensitive variant of actinin-1. This work also identifies a previously unreported exon 19a+19b expressing variant of actinin-4 in human skeletal muscle. This work finds that alternative splice variants of actinin-1 and -4 are co-expressed in a number of tissues, in particular the brain. In contrast to healthy brain, glioblastoma cells express Ca++-sensitive variants of both actinin-1 and -4. Actin-binding properties of actinin-1 and -4 are similar and are unlikely to explain isoform-specific functions. Surprisingly, this work reveals that actinin-1/-4 heterodimers, rather than homodimers, are the most abundant form of actinin in many cancer cell lines. Taken together this data suggests that actinin-1 and -4 cannot be viewed as distinct entities from each other but rather as proteins that can exist in both homodimeric and heterodimeric forms. Finally, this work employs yeast two-hybrid and proteomic approaches to identify actinin-interacting proteins. In doing so, this work identifies a number of putative actinin-4 specific interacting partners that may help to explain some of the unique functions attributed the actinin-4. The observation of alternative splice variants of actinin-1 and -4 combined with the observed potential of these proteins to form homodimers and heterodimers suggests that homodimers and heterodimers with novel actin-binding properties and interaction networks may exist. The ability to behave in this manner may have functional implications. This may be of importance considering that these proteins are central to such processes as cell migration and adhesion. This significantly alters our view of the non-muscle actinins.