[Truncated abstract] Mineralogical and geochemical characteristics were identified for regolith overlying two Australian Au deposits that discriminate mineralized and associated hydrothermally-altered rock from weathered rock that was not hydrothermally-altered. Mineralization was lithologically controlled within a previously unrecognized diorite dyke at the lower Proterozoic mesozonal Groundrush deposit, Tanami region, Northern Territory. Although hydrothermal alteration effects within the dyke were subtle and obliterated by weathering, Ti/Zr ratios clearly discriminated the diorite dyke from visually indistinguishable but generally unmineralized dolerite. In contrast, the Carboniferous Vera Nancy low-sulphidation epithermal Au deposit, located in the Drummond Basin, northeast Queensland, comprises structurally-controlled quartz veins within a relatively chemically homogenous suite of andesitic lavas and subvolcanic intrusions. A zoned hydrothermal alteration system in the hangingwall of the main vein grades from a proximal silica-pyrite alteration zone through an argillic zone into regionally extensive propylitic 'background'. Deep chemical weathering has destroyed the minerals diagnostic of the different alteration zones in bedrock to leave a kaolinitic regolith overlying all alteration zones. However, the silica-pyrite alteration zone is identified in regolith by retention of the anomalous concentrations of Au, As, Sb and Mo present in bedrock, and mineralogical characteristics, determined from X-ray diffraction investigations, discriminated weathered argillic from propylitic alteration zones. ... Metasomatic reactions, including weathering reactions, are typically difficult to specify, as some reactants and products may be removed by fluids, and thus evidence for their involvement is absent from the observed assemblages. In addition, the range of possible reactions even for relatively simple systems is such that identifying the real reaction may be intractable without additional information. Linear algebra provides an approach to this problem. If minerals and aqueous phases are represented as columns in a matrix with elements as rows, any vectors in the null space of this matrix (if it is greater than 0-dimensional) provide coefficients to balance reactions between the phases. The 'Gale' vectors for a set of phase are the row vectors of any basis for this null space. The relationships between phases are clarified through examination of these vectors in d-dimensional Gale vector space, where d is the dimension of the null space. The hyperplane normal to any vector in Gale vector space separates the space into reactant and product half-spaces. The geometric relationships between the Gale phase vectors describe all the possible reactions. Because changes to parameters (e.g. volume, mass, density) can be determined for each possible reaction, Gale analysis can be used to identify reactions consistent with these constraints. Gale analysis of weathering at the Vera deposit indicated that all the possible weathering reactions producing kaolinite, goethite and quartz from illite, pyrite and siderite resulted in minor reductions in volume and mass only, whereas acid-neutral weathering of propylitic rocks exhibited greater mass losses, consistent with observation and geochemical interpretation.

A virus-like particle (VLP) is a biological nanoparticle. It consists of the protective protein shell of a virus that is devoid of the nucleic acid required for viral replication. VLPs have two key uses: they can act as vaccines by inducing an immune response similar to their native virions, or they can facilitate gene therapy and drug delivery by encapsulating non-viral molecules and efficiently transporting them into cells. Manufacture of VLPs involves cell-based expression of virus-shell protein, with particle assembly and purification following one of two paradigms: (i) in vivo VLP assembly, followed by purification of full particles from cell lysate; (ii) partially assembled protein is recovered from cell lysate and assembled into VLPs in vitro. The flexibility and efficiency of both of these VLP manufacturing paradigms can be improved by first gaining a fundamental understanding of what is happening at key process steps. These improvements will lower the cost of VLP manufacture and enhance the viability of VLP products in the biopharmaceutical marketplace. The research reported here yielded positive outcomes for two key steps of the VLP manufacturing process, using murine polyomavirus VLPs for all experimentation. Firstly, enhanced understanding concerning the capture of virus shell protein in pentamer form (capsomeres) from cell lysate using glutathione-S-transferase (GST) affinity chromatography was obtained. It was discovered that prokaryotic expression of GST-tagged capsomeres yielded soluble aggregates having variable size distribution. Methods were developed to physically and chemically characterise these soluble aggregates, and the mechanism by which they adsorb to the chromatography resin was described using an established mathematical model. Secondly, particle characterisation of whole VLPs isolated from cell lysate was undertaken. Methods utilizing three orthogonal and quantitative techniques were developed to suggest that encapsulation of non-viral molecules (nucleic acids or proteins) during in vivo assembly causes distinct changes to the size distribution of isolated VLPs: transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation with multiple-angle light scattering (AFFFF-MALS) and electrospray differential mobility analysis (ES-DMA). The understanding gained from the research presented in this work enables the enhanced capture of partially assembled virus shell protein from cell lysate, as well as a method to efficiently and cost-effectively analyse VLP solutions for the presence of desirable or undesirable encapsulated material.

A virus-like particle (VLP) is a biological nanoparticle. It consists of the protective protein shell of a virus that is devoid of the nucleic acid required for viral replication. VLPs have two key uses: they can act as vaccines by inducing an immune response similar to their native virions, or they can facilitate gene therapy and drug delivery by encapsulating non-viral molecules and efficiently transporting them into cells. Manufacture of VLPs involves cell-based expression of virus-shell protein, with particle assembly and purification following one of two paradigms: (i) in vivo VLP assembly, followed by purification of full particles from cell lysate; (ii) partially assembled protein is recovered from cell lysate and assembled into VLPs in vitro. The flexibility and efficiency of both of these VLP manufacturing paradigms can be improved by first gaining a fundamental understanding of what is happening at key process steps. These improvements will lower the cost of VLP manufacture and enhance the viability of VLP products in the biopharmaceutical marketplace. The research reported here yielded positive outcomes for two key steps of the VLP manufacturing process, using murine polyomavirus VLPs for all experimentation. Firstly, enhanced understanding concerning the capture of virus shell protein in pentamer form (capsomeres) from cell lysate using glutathione-S-transferase (GST) affinity chromatography was obtained. It was discovered that prokaryotic expression of GST-tagged capsomeres yielded soluble aggregates having variable size distribution. Methods were developed to physically and chemically characterise these soluble aggregates, and the mechanism by which they adsorb to the chromatography resin was described using an established mathematical model. Secondly, particle characterisation of whole VLPs isolated from cell lysate was undertaken. Methods utilizing three orthogonal and quantitative techniques were developed to suggest that encapsulation of non-viral molecules (nucleic acids or proteins) during in vivo assembly causes distinct changes to the size distribution of isolated VLPs: transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation with multiple-angle light scattering (AFFFF-MALS) and electrospray differential mobility analysis (ES-DMA). The understanding gained from the research presented in this work enables the enhanced capture of partially assembled virus shell protein from cell lysate, as well as a method to efficiently and cost-effectively analyse VLP solutions for the presence of desirable or undesirable encapsulated material.

In previous studies silicon has been associated with reduced disease severity and incidence, the enhanced accumulation of phenolic compounds and lignin, and with changes in the defence-related enzyme activity and transcript abundance of defence and stress related genes. All of these aspects of plant defence were considered in this study on cotton infected with Fusarium oxysporum f. sp. vasinfectum (Fov), and the results obtained have greatly enhanced our understanding of the effects of silicon on this interaction. In all experiments conducted, defence responses were only significantly enhanced by silicon treatment following inoculation with Fov, strongly suggesting that silicon can prime defence responses in cotton infected with Fov. Sicot F-1 was the cultivar most resistant to Fov infection at the commencement of this research, whilst Sicot 189 was considered to have moderate resistance to the pathogen. Vascular discolouration was significantly reduced in the more resistant cultivar, Sicot F-1 following treatment with potassium silicate, compared to mock inoculated plants and inoculated plants treated with potassium sulphate or calcium sulphate. No significant differences between treatments were observed in the moderately resistant cultivar, Sicot 189, though further trials may need to be conducted to confirm this result. In both cultivars, silicon content was significantly greater in plants which had been treated regularly with liquid potassium silicate, rather than with calcium silicate powder. Histological investigation of cotton infected with Fov, with and without silicon treatment, was conducted to ascertain the effects of this element on the accumulation of fungitoxic phenolic compounds, cell ultrastructural changes and fungal infection structures. Fov proliferated through the cortex and stele of plants from both the resistant (Sicot F-1), and moderately resistant (Sicot 189) cultivars, regardless of silicon treatment. However, defences were more rapidly and intensely induced in endodermal and vascular regions of inoculated, potassium silicate treated Sicot F-1 plants. Significantly more phenolic compounds were present at seven days post infection (dpi) in root extracts of inoculated, potassium silicate treated Sicot F-1 plants. Phenolic compounds were not significantly increased in inoculated, potassium silicate treated root extracts of Sicot 189 plants at three or seven dpi. Lignin assays demonstrated that the dry weight percentage of lignin in root material from inoculated, potassium silicate treated Sicot F-1 plants was significantly higher than that of extracts from inoculated plants not receiving silicon treatment at three dpi. This trend was also observed at seven dpi; however lignin content was not significantly different in this case. Percentage lignin content in the roots of Sicot 189 plants was not significantly different between inoculated potassium silicate treated plants and those not treated with silicon. Histological alterations were not observed in mock inoculated water or potassium silicate treated plants, nor were any significant increases in phenolic compounds or lignin accumulation detected in control treatments not inoculated with the pathogen. The expression of several defence related genes was assessed with quantitative reverse transcriptase real-time polymerase chain reaction. The results obtained verify that potassium silicate can enhance defence responses in Sicot 189 and Sicot F-1 plants inoculated with Fov, with silicon having a more pronounced effect on the more resistant cultivar, Sicot F-1. Genes upregulated at three and four dpi in potassium silicate treated, Fov inoculated Sicot F-1 plants included peroxidase, cadinene synthase and polygalacturonase inhibiting protein (PGIP), with peroxidase associated with phenol oxidation and lignification and cadinene synthase with phytoalexin biosynthesis. Osmotin-like protein and chitinase class I were consistently upregulated in potassium silicate treated, inoculated Sicot 189 plants; both genes coding for pathogenesis related (PR) proteins, with chitinase also classified as an antifungal protein. In both cultivars, silicon treatment without Fov inoculation did not result in the significant up-regulation of any of the defence genes assessed, providing further evidence for the role of silicon in priming in this interaction. The activities of three defence related enzymes, peroxidase, chitinase and β-1, 3- glucanase was assessed in root and shoot material by colourimetric assays. Regular application of potassium silicate significantly increased the activity of peroxidase in root extracts from the highly resistant cultivar Sicot F-1, at three, four and seven dpi with Fov, and in root extracts from the moderately resistant Sicot 189 at three and four dpi. Significant increases in chitinase activity in inoculated, silicon treated Sicot 189 plants were observed in root extracts at three dpi, and in shoot extracts at four dpi. Soluble potassium silicate treatment resulted in significant increases in β-1, 3- glucanase activity in Sicot 189 root extracts at four dpi. Few significant differences between treatments in terms of chitinase and β-1, 3- glucanase activity were detected in Sicot F-1 plants, though higher levels of each of these enzymes were present in root and shoot extracts from this cultivar. In this study the effects of acibenzolar-S-methyl, applied in the form of Bion®, on defence gene expression and enzyme activity in cotton infected with Fov were more pronounced in plants cultivated from treated seed, rather than in plants treated via foliar spray; a finding which is particularly relevant to the industry presently. Significant up-regulation of chitinase class I, peroxidase, and β-1, 3-glucanase transcripts and enzyme activities occurred in the Bion® seed soak treatment with Fov inoculation compared to all other treatments. It was possible to compare the actions of silicon with those of Bion® in this study. Bion® primed defence responses in cotton infected with Fov, in a manner similar to that observed in silicon treated cotton. The use of silicon and Bion® treatments, both alone and in combination as part of integrated disease management programmes, may potentially contribute to increased protection against this pathogen in Australian cotton fields in the future.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 162-169).

Thesis (Ph.D.); Submitted to the University of California at Berkeley, Berkeley, CA (US); 1 Sep 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55024" Williams, Shara Carol. National Institutes of Health (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.

Andrologische Forschungsarbeiten der letzten Jahre beweisen, dass einzelne, aus somatischen Zellen bekannte Apoptose-typische Veränderungen bei humanen Spermien einen negativen Einfluss auf die Fertilität des Mannes haben. Umstritten ist, ob es sich dabei nur um einen abortiven Zelltod als Zeichen einer Reifungsstörung während der Spermatogenese handelt oder ob Apoptose auch in reifen Spermien induzierbar ist. Ziel der vorliegenden Arbeit war es, durch Untersuchungen zur Induzierbarkeit der Apoptose in reifen und unreifen Spermatozoen die vollständige Funktionalität verschiedener Signalkaskaden sowie deren Umsetzung in morphologische Veränderungen aufzudecken. Darüber hinaus sollte die Rolle des intrazellulären Calciumspiegels als möglicher Interaktionspartner zwischen Akrosomreaktion und Apoptose geklärt werden, um Informationen über die Zukunft der nicht fertilisierenden Spermien im weiblichen Genitaltrakt zu erlangen. In den vorliegenden Versuchsreihen konnte erstmals die gezielte Induktion der Apoptose in reifen und unreifen Spermatozoen anhand biochemischer und elektronenmikroskopischer Untersuchungen nachgewiesen werden. Dabei wurde ausführlich die erfolgreiche Aktivierung mehrerer intrinsischer Apoptosesignalwege in reifen Spermien gezeigt, deren Initiation entweder auf den Zusammenbruch innerer Mitochondrienmembranen, auf eine veränderte intrazelluläre Calciumkonzentration oder auf das Einwirken von oxidativem Stress zurückzuführen war. Zudem konnten Erkenntnisse zum antioxidativen Schutzmechanismus von Spermien gewonnen werden, welcher die Spermien gegenüber einer spezifischen Menge an H2O2 vor oxidativem Stress-bedingter Apoptose bewahrt. Sowohl die Apoptose als auch die Akrosomreaktion waren durch die Zugabe eines Calciumchelators blockierbar. Die Initiation des programmierten Zelltodes in Spermien durch einen Anstieg der intrazellulären Calciumkonzentration erklärt zudem eine weitere wichtige Funktion dieses Prozesses: das Absterben von akrosomenreagierten Spermien bei nicht erfolgter Fertilisation im weiblichen Genitaltrakt. Die Theorie einer rein abortiven Apoptose als Folge einer Spermatogenesestörung ist damit widerlegt.

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Ce travail de thèse aborde la problématique de caractérisation structurale à l'échelle atomique d'hétérostructures à base de semiconducteurs II-VI. La sonde atomique tomographique et la microscopie électronique en transmission sont utilisées de façon couplées pour obtenir la structure et la composition des interfaces dans les super-réseaux de ZnTe/CdSe afin d'améliorer leurs processus de croissance. La structure et la distribution des atomes de Cr dans le semiconducteur magnétique (Cd,Cr)Te sont aussi présentées.La sonde atomique tomographique permet d'obtenir des données quantitatives à partir de l'évaporation des semi-conducteurs ZnTe et CdSe lorsque les paramètres expérimentaux sont optimisés. Le spectre de masse à partir duquel les compositions sont extraites doit d'abord être correctement interprétés car il dépend des conditions d'évaporation. Grâce à différentes études expérimentales, il a été observé que pour détecter un mélange stœchiométrique de cations et d'anions dans les semi-conducteurs ZnTe et CdSe, il est nécessaire d'appliquer une faible tension à la pointe et des énergies d'impulsions lasers proche de 2.5 nJ à une longueur d'onde de 515 nm (vert). Régler les rapports de charge entre cation Zn++/Zn+ autour de 0.06 et Cd++/Cd+ autour de 0.35 lors de l'évaporation de différentes pointes et dans différentes sondes atomiques permet d'atteindre une composition correcte des deux couches ZnTe et CdSe. Les paramètres déterminés expérimentalement permettent de réduire la perte de détection des ions liés à leurs différents champs d'évaporations. En revanche, il est préférable de privilégier une évaporation à laser minimale à 343 nm (UV) pour optimiser la résolution spatiale de la sonde et la reconstruction 3D pour ces deux semi-conducteurs. Pour l'analyse des super-réseaux par sonde atomique, il est donc primordiale de d'abord définir l'objectif de l'expérience (précision de composition ou de reconstruction) pour pouvoir choisir les bons paramètres d'analyse.L'étude structurale des super-réseaux de ZnTe/CdSe a révélé que les interfaces sont constituées de liaisons ZnSe. La nature des interfaces a été obtenue par imagerie en contraste chimique en haute résolution, par profils de concentrations obtenus par la méthode des zêta-facteurs en EDX et par la présence d'ions moléculaires ZnSe dans le spectre de masse en sonde atomique. L'étude structurale de nombreux échantillons a prouvé la capacité des atomes de Zn et de Se à former des liaisons au détriment des liaisons CdTe. Les conditions de croissance ont été successivement améliorées pour tenir compte de ces observations et afin de forcer la formation d'interfaces de type CdTe. Malgré les précautions prises, la présence de ZnSe semble inévitable et les options encore envisagées pour obtenir ces interfaces sont réduites.La sonde atomique couplée à l'analyse chimique EDX a révélé la présence d'agglomération des atomes de Cr sous forme de zone riche large de quelques nanomètres dans le semi-conducteur magnétique dilué CdCrTe. Ces deux techniques ne permettent pas de déterminer la composition précise de ces agglomérations riches en Cr mais leurs formes semblent évoluer avec l'augmentation de la teneur en Cr dans différents échantillons. / This PhD work addresses the problem of atomic scale structural characterization of II-VI based heterostructures. The correlative use of atom probe tomography and transmission electron microscopy reveals the structure and composition of interfaces in ZnTe/CdSe superlattices to improve their growth condition. The atomic structure and the atomic Cr distribution are also revealed in (Cd,Cr)Te diluted magnetic semiconductor.When experimental parameters set in the atom probe are optimized, quantitative data can be obtain on both ZnTe and CdSe semiconductors with this technique. Compositions are obtained with the mass spectrum and it has to be correctly indexed. Experimental studies reveal that with the application of a low voltage on the tip and a moderate laser power around 2.5 nJ with a green laser (515 nm), the measured composition in ZnTe and CdSe are close to the stoichiometry between cations and anions. Setting the cations ratio Zn++/Zn+ around 0.06 et Cd++/Cd+ around 0.35 during the evaporation of the field is a reliable way to reach the optimum evaporation condition for different tips and in different atom probes. Those parameters are responsible for lowering the loss in the detection of the ions due to their different evaporation field. However, the application of a low laser power in UV (343 nm) will enhance the spatial resolution of the atom probe and the 3D reconstruction of both semiconductors. Before the evaporation of the superlattices, it is therefore compulsory to define the objectives of the experiment first.Structural studies of ZnTe/CdSe superlattices reveal that interfaces are composed of ZnSe. Their chemistry is obtain by high resolution Z-contrast images, composition profiles obtain by the zeta-factor method in EDX and by the presence of ZnSe molecular ions in the atom probe tomography mass spectrum. Many samples are investigated to highlight the ability of Zn and Se to bind together instead of Cd and Te. Growth condition are improved by taking this information into account and to force the formation of CdTe based interfaces. Despite the growth precaution, ZnSe bonds seem inevitable and it lowers the possibility to finally obtain CdTe interfaces.Atom probe tomography studies correlated with EDX chemical mapping reveal the gathering of Cr in rich region off a few nanometers in the diluted magnetic semiconductor CdCrTe. Both techniques are not reliable to get the composition of this Cr riche regions but they reveal a change in their shapes with the increase of Cr concentration in different samples.

Le domaine des nanofils semi-conducteurs est en pleine expansion depuis ces dix dernières années grâce à leurs applications dans de nombreux domaines tels que l’électronique ou la conversion d’énergie. Dans cette étude on part d’une base de nanofil de germanium (le canal), on dépose des contacts métalliques qui seront chauffés par effet joule. Une différence de potentiel est alors appliquée au contact d’entrée (la source), le courant électrique est récupéré et mesuré par le contact de sortie (le drain). Une réaction à l’état solide permet aux atomes du métal de diffuser dans le nanofil. La propagation d'une phase métal/semi-conducteur est suivie dans un microscope électronique en transmission (MET) dont la résolution permet une observation à l’échelle atomique au niveau de la source, le drain et le canal. Les dispositifs caractérisés au cours de ce stage ont été élaborés à partir de deux types de membranes, l’une plane et l’autre avec des trous. Chacune d’entre elles sont constituées d’une couche de nitrate de silicium Si3N4 à leurs surfaces présentant l’avantage d’être transparents aux électrons et isolants au courant. / Semiconductor nanowires (NWs) are promising candidates for many device applications ranging from electronics and optoelectronics to energy conversion and spintronics. However, typical NW devices are fabricated using electron beam lithography and therefore source, drain and channel length still depend on the spatial resolution of the lithography. In this work we show fabrication of NW devices in a transmission electron microscope (TEM) where we can obtain atomic resolution on the channel length using in-situ propagation of a metallic phase in the semiconducting NW independent of the lithography resolution. We show results on semiconducting NW devices fabricated on two different electron transparent Si3N4 membranes: a planar membrane and a membrane where devices are suspended over holes. First we show the process of making lithographically defined reliable electrical contacts on individual NWs. Second we show first results on in-situ propagation of a metal-semiconductor phase in Ge NWs by joule heating, while measuring the current through the device. Two different devices are studied: one with platinum metal contacts and one with copper contacts. Different phenomena can occur in CuGe NWs during phase propagation.