646 research outputs found
Effective flow properties of heterolithic, cross-bedded tidal sandstones: Part 1. Surface-based modeling
Tidal heterolithic sandstones are commonly characterized by millimeter- to centimeter-scale intercalations of mudstone and sandstone. Consequently, their effective flow properties are poorly predicted by (1) data that do not sample a representative volume or (2) models that fail to capture the complex three-dimensional architecture of sandstone and mudstone layers. We present a modeling approach in which surfaces are used to represent all geologic heterogeneities that control the spatial distribution of reservoir rock properties (surface-based modeling). The workflow uses template surfaces to represent heterogeneities classified by geometry instead of length scale. The topology of the template surfaces is described mathematically by a small number of geometric input parameters, and models are constructed stochastically. The methodology has been applied to generate generic, three-dimensional minimodels (9 m3 volume) of cross-bedded heterolithic sandstones representing trough and tabular cross-bedding with differing proportions of sandstone and mudstone, using conditioning data from two outcrop analogs from a tide-dominated deltaic deposit. The minimodels capture the cross-stratified architectures observed in outcrop and are suitable for flow simulation, allowing computation of effective permeability values for use in larger-scale models. We show that mudstone drapes in cross-bedded heterolithic sandstones significantly reduce effective permeability and also impart permeability anisotropy in the horizontal as well as vertical flow directions. The workflow can be used with subsurface data, supplemented by outcrop analog observations, to generate effective permeability values to be derived for use in larger-scale reservoir models. The methodology could be applied to the characterization and modeling of heterogeneities in other types of sandstone reservoirs
PNEUMATIC ATOMIZING NOZZLES IN FLUIDIZED BED CALCINING. I. CALIBRATION TESTS
The results of test stand studies of a pneumatic atomizing nozzle to be used in the Demonstrational Waste Calcining Facility at the Idaho Chemical Processing Plant are presented. Atomization and performance characteristics are described. The liquid feed control system for the Demonstrational Waste Calciner is compared with results of bench scale tests, and recommendations are made for improving the system. (auth
Transcriptional and epigenetic mechanisms underlying enhanced in vitro adipocyte differentiation by the brominated flame retardant BDE-47
Recent studies suggest that exposure to endocrine-disrupting compounds (EDCs) may play a role in the development of obesity. EDCs such as the flame retardant 2,2′,4,4′-tetrabrominated diphenyl ether (BDE-47) have been shown to enhance adipocyte differentiation in the murine 3T3-L1 model. The mechanisms by which EDCs direct preadipocytes to form adipocytes are poorly understood. Here, we examined transcriptional and epigenetic mechanisms underlying the induction of in vitro adipocyte differentiation by BDE-47. Quantitative high content microscopy revealed concentration-dependent enhanced adipocyte differentiation following exposure to BDE-47 or the antidiabetic drug troglitazone (TROG). BDE-47 modestly activated the key adipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPARγ) in COS7 cells, transiently transfected with a GAL4 reporter construct. Increased gene expression was observed for Pparγ2, leptin (Lep), and glucose-6-phophatase catalytic subunit (G6pc) in differentiated 3T3-L1 cells after BDE-47 exposure compared to TROG.
Methylation-sensitive high resolution melting (MS-HRM) revealed significant demethylation of three CpG sites in the Pparγ2 promoter after exposure to both BDE-47 and TROG in differentiated 3T3-L1 cells. This study shows the potential of BDE-47 to
induce adipocyte differentiation through various mechanisms that include Pparγ2 gene induction and promoter demethylation accompanied by activation of PPARγ, and possible disruption of glucose homeostasis and IGF1 signaling
Development of the State Optimism Measure
Background Optimism, or positive expectations about the future, is associated with better health. It is commonly assessed as a trait, but it may change over time and circumstance. Accordingly, we developed a measure of state optimism. Methods An initial 29-item pool was generated based on literature reviews and expert consultations. It was administered to three samples: sample 1 was a general healthy population (n = 136), sample 2 was people with cardiac disease (n = 96), and sample 3 was persons recovering from problematic substance use (n = 265). Exploratory factor analysis and item-level descriptive statistics were used to select items to form a unidimensional State Optimism Measure (SOM). Confirmatory factor analysis (CFA) was performed to test fit. Results The selected seven SOM items demonstrated acceptable to high factor loadings on a single dominant factor (loadings: 0.64–0.93). There was high internal reliability across samples (Cronbach\u27s alphas: 0.92–0.96), and strong convergent validity correlations in hypothesized directions. The SOM\u27s correlations with other optimism measures indicate preliminary construct validity. CFA statistics indicated acceptable fit of the SOM model. Conclusions We developed a psychometrically-sound measure of state optimism that can be used in various settings. Predictive and criterion validity will be tested in future studies
Structure of the Cytoplasmic Loop between Putative Helices II and III of the Mannitol Permease of Escherichia coli: A Tryptophan and 5-Fluorotryptophan Spectroscopy Study
In this work, four single tryptophan (Trp) mutants of the dimeric mannitol transporter of Escherichia coli, EIImtl, are characterized using Trp and 5-fluoroTrp (5-FTrp) fluorescence spectroscopy. The four positions, 97, 114, 126, and 133, are located in a region shown by recent studies to be involved in the mannitol translocation process. To spectroscopically distinguish between the Trp positions in each subunit of dimeric EIImtl, 5-FTrp was biosynthetically incorporated because of its much simpler photophysics compared to those of Trp. The steady-state and time-resolved fluorescence methodologies used point out that all four positions are in structured environments, both in the absence and in the presence of a saturating concentration of mannitol. The fluorescence decay of all 5-FTrp-containing mutants was highly homogeneous, suggesting similar microenvironments for both probes per dimer. However, Stern-Volmer quenching experiments using potassium iodide indicate different solvent accessibilities for the two probes at positions 97 and 133. A 5 Ã… two-dimensional (2D) projection map of the membrane-embedded IICmtl dimer showing 2-fold symmetry is available. The results of this work are in better agreement with a 7 Ã… projection map from a single 2D crystal on which no symmetry was imposed.
Recommended from our members
Double-Blind Parallel Design Pilot Study of Acetyl Levocarnitine in Patients with Alzheimer's Disease
Acetyl levocarnitine hydrochloride has been reported to retard dementia in patients with Alzheimer's disease. In a double-blind, parallel design, placebo-controlled pilot study of 30 mild to moderately demented patients with probable Alzheimer's disease, tests of memory, attention, language, visuospatial, and constructional abilities were administered, and the level of acetyl levocarnitine was measured in the cerebrospinal fluid. Patients were then randomly assigned to receive acetyl levocarnitine hydrochloride (2.5 g/d for 3 months followed by 3 g/d for 3 months) or placebo. After 6 months, the acetyl levocarnitine group demonstrated significantly less deterioration in timed cancellation tasks and Digit Span (forward) and a trend toward less deterioration in a timed verbal fluency task. No differences were found in any other neuropsychological test results. A subgroup with the lowest baseline scores, receiving acetyl levocarnitine, had significantly less deterioration on the verbal memory test and a significant increase in cerebrospinal fluid acetyl levocarnitine levels compared with those receiving placebo. These results suggest that acetyl levocarnitine may retard the deterioration in some cognitive areas in patients with Alzheimer's disease and stress the need for a larger study of this drug
TYMSTR, a putative chemokine receptor selectively expressed in activated T cells, exhibits HIV-1 coreceptor function
AbstractBackground: Chemokines bind to specific receptors and mediate leukocyte migration to sites of inflammation. Recently, some chemokine receptors, notably CXCR4 and CCR5, have been shown to be essential fusion factors on target cells for infection by human immunodeficiency virus (HIV); the chemokines bound by these receptors have also been shown to act as potent inhibitors of HIV infection. Here, we describe the isolation of a novel, putative chemokine receptor.Results: We have isolated the cDNA for a putative human chemokine receptor, which we have termed TYMSTR (T-lymphocyte-expressed seven-transmembrane domain receptor). The TYMSTR gene is localized to human chromosome 3 and encodes a protein that has a high level of identity with chemokine receptors. TYMSTR mRNA was selectively expressed in interleukin-2-stimulated T lymphocytes but not in freshly isolated lymphocytes and leukocytes or related cell lines. The natural ligand for TYMSTR was not identified among 32 human chemokines and other potential ligands. Cells co-expressing TYMSTR and human CD4 fused with cells expressing envelope glycoproteins of macrophage (M)-tropic HIV-1 as well as T-cell line (T)-tropic HIV-1 isolates. Addition of infectious, T-tropic HIV-1 particles to TYMSTR/CD4-expressing cells resulted in viral entry and proviral DNA formation.Conclusions: Our findings demonstrate that TYMSTR, in combination with CD4, mediates HIV-1 fusion and entry. The high-level expression of TYMSTR in CD4+ T lymphocytes and the selectivity of this receptor for T-tropic and M-tropic HIV-1 strains indicates that TYMSTR might function as HIV coreceptor at both early and late stages of infection
- …