The petrology and geochemistry of intrusions at selected nunataks in the Ahlmannryggen and Giaeverryggen, western Dronning Maud Land, Antarctica.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.The mid-Proterozoic Borgmassivet intrusions of western Dronning Maud Land intrude Archaean granites and a volcano-sedimentary sequence, the Ritscherflya Supergroup. They are SiO2-rich ultramafic to mafic tholeiitic rocks which occur as layered bodies of unknown dimensions and sills up to 400 m thick. This thesis records detailed field, petrographic and whole rock geochemical studies on Borgmassivet intrusions at three widely-spaced localities within an area of approximately 20 000 km in the Ahlmannryggen and Giaeverryggen. Annandagstoppane-Juletoppane-Forstefjell area: The Annandagstoppane intrusions form part of a layered body or bodies, of which only a small part is exposed. They consist of a medium-grained 'main suite ' of gabbronorites and minor anorthosites, and a Iyounger suite ' of quartz diorite pegmatites, basaltic dykes, fine- to medium-grained gabbroic sills and minor albitite veins. The main suite rocks are ortho-cumulates in which plagioclase, orthopyroxene and clinopyroxene were primocrysts which crystallized in situ. The dykes and sills show typical basaltic and doleritic textures. Geochemical evidence suggests that the main and younger suites may be consanguineous. Robertskollen-Krylen area: The layered complex at Robertskollen comprises a lower, rhythmically layered ultramafic unit, overlain by a mafic unit. Olivine, orthopyroxene and clinopyroxene are the dominant cumulus phases in the ultramafic rocks, whereas plagioclase, orthopyroxene and clinopyroxene fractionation occurred during crystallization of the mafic rocks. Metastable co-existence of quartz with olivine and anomalous incompatible trace element characteristics of the Robertskollen complex suggest contamination of the magma(s) by crustal material. The Krylen intrusions show petrographic and geochemical characteristics similar to those of the main suite at Juletoppane. A felsic dyke at Krylen may represent a rheomorphic product derived from Ritscherflya sediments. (iii) Grunehogna-Jekselen area: The Grunehogna sill is a medium-grained diorite of unknown thickness, characterized by varying amounts of plagioclase and amphibole and a high Fe-Ti oxide content. It is overlain by a 50 m-thick quartz diorite pegmatite. The overlying 400 m-thick Kullen sill varies in composition from gabbronorite to gabbro and diorite and shows evidence for contamination by crustal material. Vugs, evidence for fusion, destruction of sedimentary structures and deformation in sedimentary contact zones and xenoliths and the abundance of pegmatites suggest that the sills intruded wet, unconsolidated or partially lithified sediments. The Jekselen complex consists of quartz diorites intruding Ritscherflya sediments. Amygdales in the upper zones of the complex indicate the subvolcanic nature of the intrusion. Major, trace and rare earth element data of the Borgmassivet intrusions and the Straumsnutane basalts (Watters, 1969a, 1969b, 1972, pers. comm., 1985) show a strong regional coherence, indicating that the rocks may be consanguineous. Abundance ratio patterns ('spidergrams') of the intrusions and basalts are identical. They are consistent with crustal contamination, possibly leucotonalite, of the magmas during ascent. The present distribution of the Borgmassivet. intrusions and Straumsnutane basalts reflects emplacement at stratigraphically higher levels within the Ritscherflya Supergroup from west to east. Previous radiometric isotope studies suggested that the intrusions are approximately 1700 to 1800 Ma in age, but recent investigations show that the isotopic data are poorly understood and have to be re-evaluated. Some of the isotope characteristics may result from crustal contamination and alteration effects during intrusion into water-saturated sediments

Dynamic nuclear polarization and spin-diffusion in non-conducting solids

There has been much renewed interest in dynamic nuclear polarization (DNP), particularly in the context of solid state biomolecular NMR and more recently dissolution DNP techniques for liquids. This paper reviews the role of spin diffusion in polarizing nuclear spins and discusses the role of the spin diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in a special issue that is being published in connection with the DNP Symposium help in Nottingham in August 200

Examining the relationship between employee engagement and perceived managerial wisdom

Wisdom is very difficult to study due to the complexity of defining wisdom outright. Various models propose characteristics of individuals that are perceived as wise but wisdom finds its real application in decision making. People would characterise someone as wise if they believe that the decision made by the person (the manager in this instance) is informed by the values of all stakeholders and have long term validity. With increasing demands placed on managers to make decisions in contexts where various stakeholders and the natural environment have to be taken into consideration, managers have to make increasingly complex decisions. The decision then also has to take into consideration the values, beliefs and needs of the employees. By asking respondents to rate their manager‟s level of wisdom, why they perceive their managers as wise and what constitutes employee engagement in their minds, a relationship between employee engagement and the perception of wisdom can be deduced. The evidence suggests that especially the cognitive and emotional dimensions of employee engagement are correlated with the perception of wisdom of the manager. New models for the measurement of implicit wisdom and employee engagement are proposed. CopyrightDissertation (MBA)--University of Pretoria, 2010.Gordon Institute of Business Science (GIBS)unrestricte

Formation of Columnar Liquid Crystals on the Basis of Unconventional Triazine-Based Dendrimers by the C3-Symmetric Approach

[[abstract]]Two series of unconventional triazine-based dendrimers with C2 symmetry and C3 symmetry were prepared. The newly prepared C3-symmetrical dendrimers were characterized by 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD showed that the C3-symmetrical dendrimers display columnar liquid-crystalline phases during thermal treatment, but the C2-symmetrical dendrimers were not observed to behave correspondingly. The molecular conformations of C3- and C2-symmetrical dendrimers were obtained by computer simulation with the MM2 model of the CaChe program in the gas phase. The simulation results reasonably explain the different mesogenicities of C3- and C2-symmetric dendrimers. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks for displaying columnar liquid-crystalline behavior.[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]DE

Nuclear Magnetic Resonance Study of Ultrananocrystalline Diamonds

We report on a nuclear magnetic resonance (NMR) study of ultrananocrystalline diamond (UNCD) materials produced by detonation technique. Analysis of the 13C and 1H NMR spectra, spin-spin and spin-lattice relaxation times in purified UNCD samples is presented. Our measurements show that UNCD particles consist of a diamond core that is partially covered by a sp2-carbon fullerene-like shell. The uncovered part of outer diamond surface comprises a number of hydrocarbon groups that saturate the dangling bonds. Our findings are discussed along with recent calculations of the UNCD structure. Significant increase in the spin-lattice relaxation rate (in comparison with that of natural diamond), as well as stretched exponential character of the magnetization recovery, are attributed to the interaction of nuclear spins with paramagnetic centers which are likely fabrication-driven dangling bonds with unpaired electrons. We show that these centers are located mainly at the interface between the diamond core and shell.Comment: 25 pages, 7 figure

Scalable Architecture for a Room Temperature Solid-State Quantum Information Processor

The realization of a scalable quantum information processor has emerged over the past decade as one of the central challenges at the interface of fundamental science and engineering. Much progress has been made towards this goal. Indeed, quantum operations have been demonstrated on several trapped ion qubits, and other solid-state systems are approaching similar levels of control. Extending these techniques to achieve fault-tolerant operations in larger systems with more qubits remains an extremely challenging goal, in part, due to the substantial technical complexity of current implementations. Here, we propose and analyze an architecture for a scalable, solid-state quantum information processor capable of operating at or near room temperature. The architecture is applicable to realistic conditions, which include disorder and relevant decoherence mechanisms, and includes a hierarchy of control at successive length scales. Our approach is based upon recent experimental advances involving Nitrogen-Vacancy color centers in diamond and will provide fundamental insights into the physics of non-equilibrium many-body quantum systems. Additionally, the proposed architecture may greatly alleviate the stringent constraints, currently limiting the realization of scalable quantum processors.Comment: 15 pages, 6 figure

Dynamic nuclear polarization DNP in diamond

Here we review the recent studies on Dynamic Nuclear Polarization DNP using nitrogen vacancy centers in diamond NV . First we show the basic principles of DNP and explain its importance for Nuclear Magnetic Resonance NMR . Then we give an overview of the recently developed DNP methods, which utilize the unique properties of NV centers and demonstrate their advantages compared to conventional DNP techniques. Finally we show the potential applications of diamond based DNP for improving the sensitivity and resolution Magnetic Resoance Imaging MR

New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

X-ray diffraction analyses of the pure components n-tricosane and n-pentacosane and of their binary mixed samples have enabled us to characterize the crystalline phases observed at low temperature. On the contrary to what was announced in literature on the structural behavior of mixed samples in odd-odd binary systems with D n = 2, the three domains are not all orthorhombic. This work has enabled us to show that two of the domains are, in fact, monoclinic, (Aa, Z = 4) and the other one is orthorhombic (Pca21, Z = 4). The conclusions drawn in this work can be easily transposed to other binary systems of n-alkanes