A Mineralogical Study of a Dravitic Tourmaline from the Grenville Province

Tourmaline from a gem-quality deposit in the Grenville province has been studied with X-ray diffraction, visible-near infrared spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, electron microprobe and optical measurements. The tourmaline is found within tremolite-rich calc-silicate pods hosted in marble of the Central Metasedimentary Belt. The crystals are greenish-greyish-brown and have yielded facetable material up to 2.09 carats in size. Using the classification of Henry et al. 2011 the tourmaline is classified as a dravite, with a representative formula shown to be (Na0.73Ca0.2380.032)(Mg2+2.913Fe2+0.057Ti4+0.030) (Al3+5.787Fe3+0.017Mg2+0.14)(Si6.013O18)(BO3)3(OH)3((OH,O)0.907F0.093). Rietveld analysis of powder diffraction data gives a = 15.9436(8) Å, c = 7.2126(7) Å and a unit cell volume of 1587.8 Å3. A polished thin section was cut perpendicular to the c-axis of one tourmaline crystal, which showed zoning from a dark brown core into a lighter rim into a thin darker rim and back into lighter zonation. Through the geochemical data, three key stages of crystal growth can be seen within this thin section. The first is the core stage which occurs from the dark core to the first colourless zone; the second is from this colourless zone increasing in brown colour to the outer limit before a sudden absence of colour is noted; the third is a sharp change from the end of the second and is entirely colourless. These events are the result of metamorphism and hydrothermal fluids resulting from nearby felsic intrusive plutons. Scanning electron microscope, and electron microprobe traverses across this cross-section revealed that the green colour is the result of iron present throughout the system while the brown colour is correlated with titanium content. Crystal inclusions in the tourmaline of chlorapatite, and zircon were identified by petrographic analysis and confirmed using scanning electron microscope data and occur within the third stage of formation.

Efficient Blue Electroluminescence Using Quantum-Confined Two-Dimensional Perovskites

Solution-processed hybrid organic–inorganic lead halide perovskites are emerging as one of the most promising candidates for low-cost light-emitting diodes (LEDs). However, due to a small exciton binding energy, it is not yet possible to achieve an efficient electroluminescence within the blue wavelength region at room temperature, as is necessary for full-spectrum light sources. Here, we demonstrate efficient blue LEDs based on the colloidal, quantum-confined 2D perovskites, with precisely controlled stacking down to one-unit-cell thickness (n = 1). A variety of low-k organic host compounds are used to disperse the 2D perovskites, effectively creating a matrix of the dielectric quantum wells, which significantly boosts the exciton binding energy by the dielectric confinement effect. Through the Förster resonance energy transfer, the excitons down-convert and recombine radiatively in the 2D perovskites. We report room-temperature pure green (n = 7–10), sky blue (n = 5), pure blue (n = 3), and deep blue (n = 1) electroluminescence, with record-high external quantum efficiencies in the green-to-blue wavelength region.

Manifestation of Colossal Thermoelectric Power by Charge Ordered Small and Intermediate Bandwidth Manganites

Thermoelectric materials are revisited for various applications including power generation. The direct conversion of temperature differences into electric voltage and vice versa is known as thermoelectric effect. Possible applications of thermoelectric materials are in eco-friendly refrigeration, electric power generation from waste heat, infrared sensors, temperature controlled-seats and portable picnic coolers. Thermoelectric materials are also extensively researched upon as an alternative to compression based refrigeration. This utilizes the principle of Peltier cooling. The performance characteristic of a thermoelectric material, termed as figure of merit (ZT) is a function of several transport coefficients such as electrical conductivity (σ), thermal conductivity (κ) and Seebeck coefficient of the material (S). ZT is expressed asκσTZTS2=, where T is the temperature in degree absolute. A large value of Seebeck coefficient, high electrical conductivity and low thermal conductivity are necessary to realize a high performance thermoelectric material. The best known thermoelectric materials are phonon-glass electron – crystal (PGEC) system where the phonons are scattered within the unit cell by the rattling structure and electrons are scattered less as in crystals to obtain a high electrical conductivity. A survey of literature reveals that correlated semiconductors and Kondo insulators containing rare earth or transition metal ions are found to be potential thermoelectric materials. The structural magnetic and charge transport properties in manganese oxides having the general formula of RE1−xAExMnO3 (RE = rare earth, AE= Ca, Sr, Ba) are solely determined by the mixed valence (3+/4+) state of Mn ions. In strongly correlated electron systems, magnetism and charge transport properties are strongly correlated. Within the area of strongly correlated electron systems the study of manganese oxides, widely known as manganites exhibit unique magneto electric transport properties, is an active area of research.Strongly correlated systems like perovskite manganites, characterized by their narrow localized band and hoping conduction, were found to be good candidates for thermoelectric applications. Manganites represent a highly correlated electron system and exhibit a variety of phenomena such as charge, orbital and magnetic ordering, colossal magneto resistance and Jahn-Teller effect. The strong inter-dependence between the magnetic order parameters and the transport coefficients in manganites has generated much research interest in the thermoelectric properties of manganites. Here, large thermal motion or rattling of rare earth atoms with localized magnetic moments is believed to be responsible for low thermal conductivity of these compounds. The 4f levels in these compounds, lying near the Fermi energy, create large density of states at the Fermi level and hence they are likely to exhibit a fairly large value of Seebeck coefficient.

Optimization of Li-ion solid electrolytes

The synthesis and optimization of two Li-ion solid electrolytes were studied in this work. Different combinations of precursors were used to prepare La0.5Li0.5TiO3 via mechanosynthesis. Despite the ability to form a perovskite phase by the mechanochemical reaction it was not possible to obtain a pure La0.5Li0.5TiO3 phase by this process. Of all the seven combinations of precursors and conditions tested, the one where La2O3, Li2CO3 and TiO2 were milled for 480min (LaOLiCO-480) showed the best results, with trace impurity phases still being observed. The main impurity phase was that of La2O3 after mechanosynthesis (22.84%) and Li2TiO3 after calcination (4.20%). Two different sol-gel methods were used to substitute boron on the Zr-site of Li1+xZr2-xBx(PO4)3 or the P-site of Li1+6xZr2(P1-xBxO4)3, with the doping being achieved on the Zr-site using a method adapted from Alamo et al (1989). The results show that the Zr-site is the preferential mechanism for B doping of LiZr2(PO4)3 and not the P-site. Rietveld refinement of the unit-cell parameters was performed and it was verified by consideration of Vegard’s law that it is possible to obtain phase purity up to x = 0.05. This corresponds with the phases present in the XRD data, that showed the additional presence of the low temperature (monoclinic) phase for the powder sintered at 1200ºC for 12h of compositions with x ≥ 0.075. The compositions inside the solid solution undergo the phase transition from triclinic (PDF#01-074-2562) to rhombohedral (PDF#01-070-6734) when heating from 25 to 100ºC, as reported in the literature for the base composition. Despite several efforts, it was not possible to obtain dense pellets and with physical integrity after sintering, requiring further work in order to obtain dense pellets for the electrochemical characterisation of Li Zr2(PO4)3 and Li1.05Zr1.95B0.05(PO4)3.

MULTI-BAND BOSE HUBBARD MODELS AND EFFECTIVE THREE-BODY INTERACTIONS

Experiments with ultracold atoms in optical lattice have become a versatile testing ground to study diverse quantum many-body Hamiltonians. A single-band Bose-Hubbard (BH) Hamiltonian was first proposed to describe these systems in 1998 and its associated quantum phase-transition was subsequently observed in 2002. Over the years, there has been a rapid progress in experimental realizations of more complex lattice geometries, leading to more exotic BH Hamiltonians with contributions from excited bands, and modified tunneling and interaction energies. There has also been interesting theoretical insights and experimental studies on “un- conventional” Bose-Einstein condensates in optical lattices and predictions of rich orbital physics in higher bands. In this thesis, I present our results on several multi- band BH models and emergent quantum phenomena. In particular, I study optical lattices with two local minima per unit cell and show that the low energy states of a multi-band BH Hamiltonian with only pairwise interactions is equivalent to an effec- tive single-band Hamiltonian with strong three-body interactions. I also propose a second method to create three-body interactions in ultracold gases of bosonic atoms in a optical lattice. In this case, this is achieved by a careful cancellation of two contributions in the pair-wise interaction between the atoms, one proportional to the zero-energy scattering length and a second proportional to the effective range. I subsequently study the physics of Bose-Einstein condensation in the second band of a double-well 2D lattice and show that the collision aided decay rate of the con- densate to the ground band is smaller than the tunneling rate between neighboring unit cells. Finally, I propose a numerical method using the discrete variable repre- sentation for constructing real-valued Wannier functions localized in a unit cell for optical lattices. The developed numerical method is general and can be applied to a wide array of optical lattice geometries in one, two or three dimensions.

Synthesis and proton conduction properties of lanthanide amino-sulfophosphonates

Crystalline acid-functionalized metal phosphonates are potential candidates as proton conducting electrolytes. Their frameworks can be chemically modified to contain proton carriers such as acidic groups (P-OH; -SO3H, -COOH,…) and guest molecules (H2O, NH3,…) that generates hydrogen bond networks stable in a wide range of temperature [1,2]. In this work, focus is laid on properties derived from the combination of lanthanide ions with the amino-sulfophosphonate ligand (H2O3PCH2)2-N-(CH2)2-SO3H. Hightrough-put screening was followed to reach the optimal synthesis conditions under solvothermal conditions at 140 ºC. Isolated polycrystalline solids, Ln[(O3PCH2)2-NH-(CH2)2-SO3H].2H2O (Ln= La, Pr and Sm), crystallize in the monoclinic (La) and orthorhombic (Pr and Sm) systems with unit cell volume of ~2548 Å3. Preliminary proton conductivity measurements for Sm derivative have been carried out between 25º and 80 ºC at relative humidity (RH) values of 70 % and 95 %. The sample exhibits enhanced conductivity at high RH and T (Figure 1) and constant activation energies of 0.4 eV, typical of a Grothuss mechanism of proton.

Crystal structure of Bn IV in complex with myristic acid: A Lys49 myotoxic phospholipase A(2) from Bothrops neuwiedi venom

The LY549-PLA(2)s myotoxins have attracted attention as models for the induction of myonecrosis by a catalytically independent mechanism of action. Structural studies and biological activities have demonstrated that the myotoxic activity of LYS49-PLA(2) is independent of the catalytic activity site. The myotoxic effect is conventionally thought to be to due to the C-terminal region 111-121, which plays an effective role in membrane damage. In the present study, Bn IV LYS49-PLA(2) was isolated from Bothrops neuwiedi snake venom in complex with myristic acid (CH3(CH2)(12)COOH) and its overall structure was refined at 2.2 angstrom resolution. The Bn IV crystals belong to monoclinic space group P2(1) and contain a dimer in the asymmetric unit. The unit cell parameters are a = 38.8, b = 70.4, c = 44.0 angstrom. The biological assembly is a "conventional dimer" and the results confirm that dimer formation is not relevant to the myotoxic activity. Electron density map analysis of the Bn IV structure shows clearly the presence of myristic acid in catalytic site. The relevant structural features for myotoxic activity are located in the C-terminal region and the Bn IV C-terminal residues NKKYRY are a probable heparin binding domain. These findings indicate that the mechanism of interaction between Bn IV and muscle cell membranes is through some kind of cell signal transduction mediated by heparin complexes. (C) 2010 Elsevier Masson SAS. All rights reserved.

Selective Inner Hair Cell Loss in Prematurity: A Temporal Bone Study of Infants from a Neonatal Intensive Care Unit

Premature birth is a well-known risk factor for sensorineural hearing loss in general and auditory neuropathy in particular. However, relatively little is known about the underlying causes, in part because there are so few relevant histopathological studies. Here, we report on the analysis of hair cell loss patterns in 54 temporal bones from premature infants and a control group of 46 bones from full-term infants, all of whom spent time in the neonatal intensive care unit at the Hospital de Nios in San Jose, Costa Rica, between 1977 and 1993. The prevalence of significant hair cell loss was higher in the preterm group than the full-term group (41% vs. 28%, respectively). The most striking finding was the frequency of selective inner hair cell loss, an extremely rare histopathological pattern, in the preterm vs. the full-term babies (27% vs. 3%, respectively). The findings suggest that a common cause of non-genetic auditory neuropathy is selective loss of inner hair cells rather than primary damage to the cochlear nerve.

Molecular Characterization of Strains of Respiratory Syncytial Virus Identified in a Hematopoietic Stem Cell Transplant Outpatient Unit Over 2 Years: Community or Nosocomial Infection?

Respiratory syncytial virus (RSV) is recognized as the leading cause of nosocomial respiratory infection among hematopoietic stem cell transplant (HSCT) recipients, causing considerable morbidity and mortality. RSV is easily transmitted by contact with contaminated surfaces, and in HSCT units, more than 50% of RSV infections have been characterized as of nosocomial origin. From April 2001 to October 2002, RSV was identified by direct immunofluorescent assay in 42 symptomatic HSCT recipients. Seven RSV strains from 2001 and 12 RSV strains from 2002 were sequenced. RNA extraction, cDNA synthesis, and seminested polymerase chain reaction (PCR) with primers complementary to RSV genes G and F were pet-formed. PCR products were analyzed by nucleotide sequencing of the C-terminal region of gene G for typing (in group A or B). Of the 7 strains analyzed in 2001, only 2 belonged to group B; the other 5 belonged to group A. Of these 7 strains, 3 were identical and were from recipients receiving outpatient care. In 2002, of the 12 strains analyzed, 3 belonged to group A and the other 9 belonged to group B. Of these 9 strains, 7 were genetically identical and were also from recipients receiving outpatient care. Therefore, multiple strains of RSV cocirculated in the hematopoietic stem cell transplant units (ward and outpatient units) between 2001 and 2002. Nosocomial transmission was more likely to occur at the HSCT outpatient unit than in the HSCT ward. Infection control practices should also be implemented in the outpatient setting.

Re-mapping the molecular features of the human immunodeficiency virus type 1 and human T-cell lymphotropic virus type 1 Brazilian sequences using a bioinformatics unit established in Salvador, Bahia, Brazil, to give support to the viral epidemiology studies

The analysis of genetic data for human immunodeficiency virus type 1 (HIV-1) and human T-cell lymphotropic virus type 1 (HTLV-1) is essential to improve treatment and public health strategies as well as to select strains for vaccine programs. However, the analysis of large quantities of genetic data requires collaborative efforts in bioinformatics, computer biology, molecular biology, evolution, and medical science. The objective of this study was to review and improve the molecular epidemiology of HIV-1 and HTLV-1 viruses isolated in Brazil using bioinformatic tools available in the Laboratório Avançado de Sáude Pública (Lasp) bioinformatics unit. The analysis of HIV-1 isolates confirmed a heterogeneous distribution of the viral genotypes circulating in the country. The Brazilian HIV-1 epidemic is characterized by the presence of multiple subtypes (B, F1, C) and B/F1 recombinant virus while, on the other hand, most of the HTLV-1 sequences were classified as Transcontinental subgroup of the Cosmopolitan subtype. Despite the high variation among HIV-1 subtypes, protein glycosylation and phosphorylation domains were conserved in the pol, gag, and env genes of the Brazilian HIV-1 strains suggesting constraints in the HIV-1 evolution process. As expected, the functional protein sites were highly conservative in the HTLV-1 env gene sequences. Furthermore, the presence of these functional sites in HIV-1 and HTLV-1 strains could help in the development of vaccines that pre-empt the viral escape process.

Modeling and Control of the Power Conversion Unit in a Solid Oxide Fuel Cell Environment

In this doctoral thesis, a power conversion unit for a 10 kWsolid oxide fuel cell is modeled, and a suitable control system is designed. The need for research was identified based on an observation that there was no information available about the characteristics of the solid oxide fuel cell from the perspective of power electronics and the control system, and suitable control methods had not previously been studied in the literature. In addition, because of the digital implementation of the control system, the inherent characteristics of the digital system had to be taken into account in the characteristics of the solid oxide fuel cell (SOFC). The characteristics of the solid oxide fuel cell as well the methods for the modeling and control of the DC/DC converter and the grid converter are studied by a literature survey. Based on the survey, the characteristics of the SOFC as an electrical power source are identified, and a solution to the interfacing of the SOFC in distributed generation is proposed. A mathematical model of the power conversion unit is provided, and the control design for the DC/DC converter and the grid converter is made based on the proposed interfacing solution. The limit cycling phenomenon is identified as a source of low-frequency current ripple, which is found to be insignificant when connected to a grid-tied converter. A method to mitigate a second harmonic originating from the grid interface is proposed, and practical considerations of the operation with the solid oxide fuel cell plant are presented. At the theoretical level, the thesis discusses and summarizes the methods to successfully derive a model for a DC/DC converter, a grid converter, and a power conversion unit. The results of this doctoral thesis can also be used in other applications, and the models and methods can be adopted to similar applications such as photovoltaic systems. When comparing the results with the objectives of the doctoral thesis, we may conclude that the objectives set for the work are met. In this doctoral thesis, theoretical and practical guidelines are presented for the successful control design to connect a SOFC-based distributed generation plant to the utility grid.

Automation of Chemical Spray Pyrolysis Unit and Fabrication of Sprayed CuInS2/In2S3 Solar Cell

Aim of the present work was to automate CSP process, to deposit and characterize CuInS2/In2S3 layers using this system and to fabricate devices using these films.An automated spray system for the deposition of compound semiconductor thin films was designed and developed so as to eliminate the manual labour involved in spraying and facilitate standardization of the method. The system was designed such that parameters like spray rate, movement of spray head, duration of spray, temperature of substrate, pressure of carrier gas and height of the spray head from the substrate could be varied. Using this system, binary, ternary as well as quaternary films could be successfully deposited.The second part of the work deal with deposition and characterization of CuInS2 and In2S3 layers respectively.In the case of CuInS2 absorbers, the effects of different preparation conditions and post deposition treatments on the optoelectronic, morphological and structural properties were investigated. It was observed that preparation conditions and post deposition treatments played crucial role in controlling the properties of the films. The studies in this direction were useful in understanding how the variation in spray parameters tailored the properties of the absorber layer. These results were subsequently made use of in device fabrication process.Effects of copper incorporation in In2S3 films were investigated to find how the diffusion of Cu from CuInS2 to In2S3 will affect the properties at the junction. It was noticed that there was a regular variation in the opto-electronic properties with increase in copper concentration.Devices were fabricated on ITO coated glass using CuInS2 as absorber and In2S3 as buffer layer with silver as the top electrode. Stable devices could be deposited over an area of 0.25 cm2, even though the efficiency obtained was not high. Using manual spray system, we could achieve devices of area 0.01 cm2 only. Thus automation helped in obtaining repeatable results over larger areas than those obtained while using the manual unit. Silver diffusion on the cells before coating the electrodes resulted in better collection of carriers.From this work it was seen CuInS2/In2S3 junction deposited through automated spray process has potential to achieve high efficiencies.

From a discrete to a continuum model of cell dynamics in one dimension

Multiscale modeling is emerging as one of the key challenges in mathematical biology. However, the recent rapid increase in the number of modeling methodologies being used to describe cell populations has raised a number of interesting questions. For example, at the cellular scale, how can the appropriate discrete cell-level model be identified in a given context? Additionally, how can the many phenomenological assumptions used in the derivation of models at the continuum scale be related to individual cell behavior? In order to begin to address such questions, we consider a discrete one-dimensional cell-based model in which cells are assumed to interact via linear springs. From the discrete equations of motion, the continuous Rouse [P. E. Rouse, J. Chem. Phys. 21, 1272 (1953)] model is obtained. This formalism readily allows the definition of a cell number density for which a nonlinear "fast" diffusion equation is derived. Excellent agreement is demonstrated between the continuum and discrete models. Subsequently, via the incorporation of cell division, we demonstrate that the derived nonlinear diffusion model is robust to the inclusion of more realistic biological detail. In the limit of stiff springs, where cells can be considered to be incompressible, we show that cell velocity can be directly related to cell production. This assumption is frequently made in the literature but our derivation places limits on its validity. Finally, the model is compared with a model of a similar form recently derived for a different discrete cell-based model and it is shown how the different diffusion coefficients can be understood in terms of the underlying assumptions about cell behavior in the respective discrete models.

First-dimension separation with the MicroRotoforTM cell prior to SDS-PAGE and LC-MS/MS analysis

Free-flow isoelectric focusing (IEF) is a gel-free method for separating proteins based on their isoelectric point (pl) in a liquid environment and in the presence of carrier ampholytes. this method has been used with the RotoforTM cell at the preparative scale to fractionate proteins from samples containing several hundred milligrams of protein; see the refeences listed in Bio-Rad bulletin 3152. the MicroRotofor cell applies the same method to much sl=maller protein samples without dilution, separating and recoverng milligram quantities of protein in a total volume of about 2 ml.

Clinical outcome in chronic myeloid leukemia after allogeneic hematopoietic stem cell transplantation: The experience of the Bone Marrow Transplantation Unit of FUNFARME/BRAZIL using FISH

Investigation of the efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in chronic myeloid leukemia patients is essential to predict prognosis and survival. In 20 patients treated at the Bone Marrow Transplantation Unit of São José do Rio Preto (São Paulo, Brazil), we used fluorescence in situ hybridization (FISH) to investigate the frequency of cells with BCR/ABL rearrangement at diagnosis and at distinct intervals after allo-HSCT until complete cytogenetic remission (CCR). We investigated the disease-free survival, overall survival in 3 years and transplant-related mortality rates, too. Bone marrow samples were collected at 1, 2, 3, 4, 6, 12, and 24 months after transplantation and additional intervals as necessary. Success rate of the FISH analyses was 100%. CCR was achieved in 75% of the patients, within on average of 3.9 months; 45% patients showed CCR within 60 days after HSCT. After 3 years of the allo-HSCT, overall survival rate was 60%, disease-free survival was 50% and the transplant-related mortality rate was 40%. The study demonstrated that the BCR-ABL FISH assay is useful for follow-up of chronic myeloid leukemia patients after HSCT and that the clinical outcome parameters in our patient cohort were similar to those described for other bone marrow transplantation units. ©FUNPEC-RP.