[pt] Este trabalho é uma investigação da microestrutura e cinética dos fenômenos de precipitação que ocorrem na Liga 33 (Fe-Ni-Cr-Mo-Cu-N), sistema metálico desenvolvido pela Krupp VDM com o intuito de suportar altas temperaturas e ambiente corrosivo. A Liga 33 incorre precipitação contínua e descontínua simultaneamente, como resultado do tratamento de envelhecimento realizado numa faixa de temperatura correspondente àquela que o material atinge quando submetido a um processo de soldagem. A caracterização microestrutural foi realizada por microscopia ótica, microscopia eletrônica de varredura, e microscopia eletrônica de transmissão, incluindo microanálise, devido à ordem de grandeza nanométrica das fases precipitadas. A precipitação descontínua ocasiona uma estrutura lamelar no contorno dos grãos, resultado do crescimento cooperativo entre as lamelas, envolvendo átomos substitucionais (Cr, por exemplo) e intersticiais (N). A precipitação contínua ocorre no interior dos grãos gerando precipitados com diferentes morfologias. A microanálise revela que os produtos gerados em ambas as reações crescem competindo pelo Cr. Uma análise cinética- morfológica aponta para a natureza não estacionária da reação descontínua, que sofre gradativa diminuição de sua taxa de transformação, até ser totalmente paralisada. / [en] This work is an investigation of the microstructure and kinetics of the phenomena occurring inside Alloy 33 (Fe-Ni- Cr-Mo-Cu-N), a metallic system developed by Krupp VDM to endure high temperatures and corrosive environment. Alloy 33 incurs continuous and discontinuous precipitation simultaneously, as a result of the aging treatment induced in a temperature range correspondent to the one of a welding process in the referred material. The microstructural characterization was performed by optical microscopy, scanning electron microscopy and transmission electron microscopy, including microanalysis, due to the nanometric nature of the precipitated phases. Discontinuous precipitation produces a lamellar structure along grain boundaries as a result of a cooperative growth between the lamellae, involving substitucional and interstitial atoms, Cr and N respectively. Continuous precipitation occurs inside grains, generating precipitates with different morphologies. Microanalysis reveals that products of both precipitation reactions grow competing for Cr. A kinetic-morphological analysis points to the non-stationary characteristic of the discontinuous precipitation, where the transformation rate diminishes until it stops completely, as aging occurs.

Philosophiae Doctor - PhD / Solute carrier transporters belonging to the major facilitator family of membrane transporter are increasingly being recognized as a possible mechanism to explain inter-individual variation in drug efficacy and response. Genetic factors are estimated to be responsible for approximately 15-30% of inter-individual variation in drug disposition and response. The aims of this study were to determine the minor allele frequencies of 78 previously identified single nucleotide polymorphisms in the pharmacogenomically relevant SLC22A1-3 and SLCO1B1 genes in the Admixed population of South Africa. Thereafter, to determine whether allele and genotype frequencies for these SNP were different from that reported for other African, Caucasian, and Asian populations. The inferred haplotypes from the genetic information possessed the potential to subsequently be used in future to design and interpret results of pharmacogenomic association studies involving these genes and their substrate drugs. Furthermore, to determine whether the Cape Admixed population harbour novel SNPs in the proximal promoter regions of SLC22A1- 3 and SLCO1B1-3 genes, that encodes hOCT1-3 and hOATP1 and hOATP3, respectively. SNaPshot™ multiplex single base mini-sequencing systems were developed and optimized for each of SLC22A1, SLC22A2, SLC22A3, and SLCO1B1 genes covering the previously identified 78 SNPs. These systems were then used to genotype the alleles of 130 healthy Cape Admixed subjects residing in Cape Town, South Africa. In addition, the proximal promoter regions of the SLC22A1-3 and SLCO1B1-3 genes of 96 of the participants were screened for novel SNPs by direct sequencing. The Cape Admixed subjects investigated displayed a lack of variation and were monomorphic for 78% of the SNPs screened. None of the SLC22A3 SNPs investigated was observed in this study. Sequencing of the proximal promoter regions of the SLC22 and SLCO genes did not reveal any novel SNPs in the 96 Cape Admixed subjects that were screened. This study highlights the fact that African populations do not have the same allele frequencies for SNPs in harmacogenomically relevant genes. Furthermore, the Cape Admixed and other African populations do not share all reduced-function variants of the SLC22A1-3 and SLCO1B1-3 genes with Caucasian and Asian populations. In addition, previously identified novel regulatory variants in SLC22A2 did not exhibit a significant effect on the ability of the promoter to drive transcription. However, it must be noted that these results were observed at 95% confidence interval, and that a 99% confidence interval the significance may increase theoretically. Additionally, it should be noted that more intensive studies are required to determine the potential effect these novel variants may well cause. This study lays the foundation for the design and interpretation of future pharmacogenomic association studies between the variant alleles of the SLC22A and SLCO genes in the Cape Admixed population, as well as optimizations for future expression, and more importantly, drug transport assays with respect to drug disposition and efficacy. / National Research Foundation (NRF) and the Medical Research Council (MRC)

<p>Ni-based superalloys have been widely used for high temperature applications such as turbine blades for jet propulsion and power plants due to their excellent creep, fatigue, and corrosion resistance. But as the demand for higher temperature capability and strength increases, there remains a need to better understand high temperature deformation mechanisms and improve and strengthen superalloys at these elevated temperatures. Recently, a correlation has been observed between solute segregation at planar defects (stacking faults, antiphase boundaries, etc) and enhanced high temperature creep properties – known colloquially as phase transformation strengthening. Experimentally, regardless of alloy composition, strong Co segregation at planar defects along with Cr has been observed. In addition, it has been suggested by density functional theory work that Co would promote Cr concentration at stacking faults by forming strong Cr-Co bonds. Based on these findings, it was hypothesized the presence of Co provides a significant thermodynamic driving force for segregation to planar defects. </p><p>In order to further investigate the correlation between solute segregation and deformation mechanisms the fabrication of a planar front single crystal Ni-based superalloy and its microstructure, alloy composition, and microhardness properties of the as-zone melted and solution heat treated states were investigated and compared to the directionally-solidified state to study the effect of microsegregation on these alloy characteristics. Next, new Co-containing, Cr-free alloys are designed to optimize g-g’ volume fraction, size, and morphology to mimic microstructures observed in single crystal superalloys. The general alloy design strategy and approach are outlined, and the composition, microstructure, phase transformation temperatures, and mechanical properties of new Cr-free and Co-containing alloys are reported. A new set of Cr-free alloys have thus been designed, with modifications of Nb, Ta, and Ti additions ranging from 3 to 7 at.% to investigate the role of these elements on the phase transformation strengthening mechanism at elevated temperatures.</p><p></p>

Up-to-date methods of numerical modelling of random fields were applied to investigate some features of solute transport in saturated porous media with stochastic hydraulic conductivity. The paper describes numerical experiments which were performed and presents the first results.

In the recent decades, therehave been frequent conflicts between groundwater waterresources and environmentally hazardous activities. Newmethodologies for aiding decision-making in groundwater impactassessment and protection areneeded and in which issues ofincreased awareness, better understanding of the groundwaterresources processes, and validation of predictive mathematicalmodels are addressed. A framework fordecision–aid, based on predictive simulations that a)predicts the environmental impacts b) provides the totaleconomical value c) visualises the impacts and the groundwaterproperties and d) describes the uncertainties in the results isproposed herein. The framework can be applied in environmentalimpact assessments, strategic environmental assessments andprotection and management of water resources. The results ofthe model are used as feedback for determining new scenarios,depending on the required uncertainties, and if the plannedactivity is sustainable, and/or fulfils the legislative andpolicy measures. This framework is applied to a particular casestudy, Nybroåsen, in the south-eastern part of Sweden,where the highway E22 is constructed through the importantglaciofluvial esker aquifer, passing the protection zone of thewater supply for the Kalmar municipality. The impacts from the new highwayand the existing road have been predicted by two-dimensionalphysically based time-variant flow and solute groundwatermodelling. The results, breakthrough curves of contaminantconcentration in wells and maps of concentration distributions,as well as travel times, flow paths, and capture zones forwells determined by particle tracking have been presented. The constructed model of theNybroåsen study area was calibrated by comparing observedand simulated groundwater levels for 15 observation wells forten years of measurements. The model has been evaluated bothgraphically and numerically and the calibration target wasfulfilled for 13 of the 15 observation wells. The model workincludes investigations of the catchment information, a waterbalance study, simulation of the groundwater recharge,consideration of the unsaturated zone by a numerical columnsimulation, and sensitivity analysis. From the sensitivity analysis ofthe flow and transport parameters, it has been shown that theuncertainties are mainly due to the hydraulic conductivity.Comparison of the derived conductivity from the steady-stateautomatic calibration and the time-variant calibration showedthat there are major differences in the derived parameters,which illustrates the importance of a time dependentcalibration over both wet and dry periods and in more than onepoint in the area of interest of the model predictions. In addition, a multi-criteriadecision analysis has been carried out for four roadalternatives (including the new highway E22) and the existingroad in the case study concerned. The multi-criteria decisionaid is applied as an illustration of how it can be used in thestudy area to identify a) interest groups of actors and theirconcerns b) ranking of alternative road scenarios according toactors’preferences and c) coalition groups of actorsi.e.groups that have similar views with regard to theroad alternatives. <b>Keywords:</b>Physically-based groundwater modelling,contamination, flow and solute transport, glaciofluvialdeposits, Nybroåsen, Sweden, and multi-criteriadecision-aid. / NR 20140805

This article presents the derivation of the thermodynamic expressions for the activation free energy and reaction rate constant for cosolvent reaction systems. These expressions account for the factors that are specific to solution-phase reactions, which include isotropic electrostatic effects and close-range solvent−solute interactions. This article discusses the idea that electrostatic effects can be correlated with the isotropic relative permittivity, and solvent−solute interactions can be correlated with the cosolvent mole fraction. This article also shows that this type of thermodynamic analysis is necessary for understanding certain nuances of solution-phase reaction processes not tractable by other types of analyses.

The oncogene c-MYC has guanine-rich and complementary cytosine-rich sequences in its P1 promoter region. The P1 promoter is responsible for over 90% of the c-MYC expression. Downregulation of c-MYC expression represents a novel therapeutic approach to more than 50% of all cancers. A stable i-motif formed by the c-MYC C-rich sequence would be an attractive target for cancer treatment. We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). The question is whether c-MYC promoter sequence i-motif will be stable at physiological pH. In this work, we have investigated the stability of mutant c-MYC i-motif in solutions having pH values from 4 to 7 and containing co-solutes or molecular crowding agents. The crowded nuclear environment was modeled by the addition of polyethylene glycol (PEG, having molecular weights from 200 to 12000 g/mol) at concentrations of 10% to 40% w/w. Circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC) were used to establish the presence and stability of c-MYC i-motifs in buffer solutions having pH values of 4 to 7. The results of these studies are: 1) the addition of up to 20% w/w glycerol does not increase i-motif stability, 2) the addition of 30% PEG results in an increase in i-motif stability to pH values as high as 6.7, 3) i-motif stability is increased with increased PEG concentration and increased PEG molecular weight, and 4) the effects of PEG size and concentration are not linear, with larger PEGs forming DNA/PEG complexes, which destabilize the i-motif. In summary, we have shown that the c-MYC i-motif can exist as a stable structure at pH as high as 6.7 in a crowded environment. Molecular crowding, largely an excluded volume effect, drives the formation of the more compact i-motif, even at higher pH values where the cytosine imino-nitrogen is deprotonated and neutral C-C pairs can form only two H-bonds. Based on this research, it seems possible that a stable c-MYC promoter sequence i-motif could form at physiological pH and would be a reasonable drug target for new cancer therapies.

This article presents reaction rate data for the simple hydrolysis of acetic anhydride in the acetonitrile/water and acetone/water cosolvent systems and regression analyses using recently developed thermodynamic rate equations that contain electrostatic and solvent-solute terms. The isomole fraction plots for these reaction systems are linear, and previous theoretical work has shown that the electrostatic term is negligible for such systems. On the other hand, the reaction rates are dependent upon the cosolvent mole fraction, indicating that the solvent-solute term, which is modeled empirically, is significant. The results of the analyses provide the foundation for a paradigm shift away from the emphasis on electrostatic effects to more tenable explanations of kinetic behavior in solvent systems.

No description available.

The physiological responses to salt stress were measured in Chenopodium quinoa. In a greenhouse experiment, salt water was applied to the quinoa varieties, Chipaya and KU-2, and to the model halophyte Thellungiella halophila to assess their relative responses to salt stress. Height and weight data from a seven-week time course demonstrated that both cultivars exhibited greater tolerance to salt than T. halophila. In a growth chamber experiment, three quinoa cultivars, Chipaya, Ollague, and CICA 17 were hydroponically grown and physiological responses were measured with four salt treatments. Tissues collected from the growth chamber treatments were used to obtain leaf succulence data, tissue ion concentrations, compatible solute concentrations, and RNA for real-time PCR. Stomatal conductance and fresh weight were measured to determine the degree of stress and recovery. The expression profiles of SOS1, NHX1, and TIP2, genes involved in salt stress, showed constitutive expression in root tissue and up-regulation in leaf tissue in response to salt stress. These data suggest that quinoa tolerates salt through a combination of exclusion and accumulation mechanisms.