Analysis of signal propagation in optically coupled detectors for digital mammography: II. Lens and fibre optics

An x-ray detector for digital x-ray mammography is under investigation, which consists of a phosphor screen coupled by a demagnifying fibre-optic taper to a time-delay integration mode, charge-coupled device (CCD) image array. The signal propagation through such a detector depends on the intensity and angular emission of light from the phosphor screen, the angular acceptance and transmission of light through the optics, and the spectral sensitivity of the CCD to the fluorescent light. The production of light by the phosphor screen was considered in a previous paper. Here, the issues related to the optics are examined. For phosphor screens coupled by lenses with limiting acceptance angles of less than 30 degrees, it was calculated that the coupling efficiency would be 10% greater than would be estimated under the assumption of a Lambertian source. These increases occur because a phosphor screen typically produces light which is more forward directed than a Lambertian source. Similar increases in efficiency are observed when a phosphor screen is coupled to a fibre-optic faceplate or taper. For fibre optics, exact estimation of the optical coupling efficiency requires knowledge of the angular-dependent transmission efficiency of the fibres.     

Structural brain changes in early‐onset and late‐onset depression: An update of volumetric MRI findings

Early‐onset (EOD) and late‐onset depression (LOD) are associated with different neuropsychological syndromes and structural brain changes. In this article, neuroimaging studies examining structural brain changes in elderly depressed patients are reviewed. The presented findings support current assumptions that depression in the elderly generally is associated with volume reductions in brain structures, notably in the hippocampus and the orbitofrontal cortex (OFC). Concerning structural cerebral differences between EOD and LOD, the review yielded conflicting results—only for OFC, but not for amygdala or hippocampus, pronounced effects in LOD than in EOD can be assumed. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 149–160, 2014     

An integrated system for publishing environmental observations data

Over the next decade, it is likely that science and engineering research will produce more scientific data than has been created over the whole of human history. The successful use of these data to achieve new scientific breakthroughs will depend on the ability to access, integrate, and analyze these large datasets. Robust data organization and publication methods are needed within the research community to enable data discovery and scientific analysis by researchers other than those that collected the data. We present a new method for publishing research datasets consisting of point observations that employs a standard observations data model populated using controlled vocabularies for environmental and water resources data along with web services for transmitting data to consumers. We describe how these components have reduced the syntactic and semantic heterogeneity in the data assembled within a national network of environmental observatory test beds and how this data publication system has been used to create a federated network of consistent research data out of a set of geographically decentralized and autonomous test bed databases.     

Complex metal oxide catalysts for selective oxidation of propane and derivatives: II. The relationship among catalyst preparation, structure and catalytic properties

The effects of the preparation methods on the structure and catalytic performance of the MVTeNb (M=Mo or W) complex metal oxides (CMO) in selective oxidation of propane to acrylic acid (AA) were investigated. Preparation methods can play as significant roles as the chemical composition in determining the structures and catalytic properties of a CMO catalyst. Undesirable preparation methods or conditions can lead to the formation of ineffective crystal phases in the resulting catalysts, leading to poor catalytic activity or selectivity. An effective MoVTeNb oxide catalyst for propane selective oxidation to acrylic acid could be obtained with a combination of a proper metal ratio and proper preparation procedures. Certain drying methods, such as freeze dry and heat evaporation, are undesirable because phase segregation tends to occur during such processes, which negatively affect the catalytic performance. The preferred drying method is the rotavap method, which favors the formation of an effective crystal phase and suppresses the formation of impurity phases. The preferred calcination atmosphere is an inert atmosphere while a calcination atmosphere containing oxygen leads to the formation of significant amounts of MO₃ in MVTeNb oxides (M=Mo or W), which is known to be inactive in propane oxidation. It is proposed that an effective MoVTeNb oxide catalyst for propane selective oxidation to acrylic acid should contain at least two major crystal Phases A and B. Based on studies of oxides of pure Phase A and those exclusively enriched with Phase B, X-ray diffraction (XRD) characteristics of the two major crystal phases (A and B) have been identified and their catalytic functions studied. It is proposed that Phase A is active in propane activation but relatively unselective for the acrylic acid formation, while Phase B is reasonably active for propane activation and fairly selective for acrylic acid formation. It has been shown that using MoVTeNb oxide catalyst with a proper ratio of Phases A and B and synergy between them, very high propane conversion (73%) and acrylic acid selectivity (58%) can be achieved at the same time.     

Dye flocculation using polyampholytes and polyelectrolyte‐surfactant nanoparticles

In this article, we report on the dye flocculation performance of polyampholytes containing hydrophobically modified cationic, hydrophilic nonionic, and anionic monomer units, always with an excess of cationic charges. The results are compared with homopolymers and with those obtained using nonstoichiometric polyelectrolyte–surfactant complex (PSC) dispersions with adjustable surface charge density. The polyampholytes as well as the PSC can successfully remove the dye Celliton Fast Blue (Dispers blue 3). The efficiency of dye separation is mainly influenced by the charge of polymers or complexes, demonstrating that charge neutralization is one flocculation mechanism. However, PSC, which are almost neutral, are also able to remove the dye due to their size and structure. In this case, the degree of dye removal is a little bit better and the so‐called flocculation window is broader as in the case of charge neutralization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1342–1349, 2007     

GLC and NMR analysis of isomeric impurities in the new anti-inflammatory agent benoxaprofen

GLC and NMR methods are described for the determination of four possible isomeric impurities in the novel anti-inflammatory agent benoxaprofen. The 2- and 3-chlorophenyl isomers were determined by GLC after alkaline hydrolysis and subsequent methylation. A rapid NMR procedure, using the lanthanide shift reagent tris- (1, 1, 1, 2, 2, 3, 3-heptafluoro- 7, 7-dimethyl- 4, 6-octanedionato)-europium, was developed for the 6- and 7- (alpha-methylacetic acid) isomers. Similar methodolology, with tris-(3-heptafluorobutyryl-d-camphorato)europium, enabled the determination of the enantiomer ratio for benoxaprofen. For the positional isomers, the limits of detection were 0.05% by GLC and 0.2% by NMR.     

Uranium and technetium bio-immobilization in intermediate-scale physical models of an in situ bio-barrier

We investigated the long-term effects of ethanol addition on U and Tc mobility in groundwater flowing through intermediate-scale columns packed with uncontaminated sediments. The columns were operated above-ground at a contaminated field site to serve as physical models of an in situ bio-barrierfor U and Tc removal from groundwater. Groundwater containing 4 microM U and 520 pM Tc was pumped through the columns for 20 months. One column received additions of ethanol to stimulate activity of indigenous microorganisms; a second column received no ethanol and served as a control. U(VI) and Tc(VII) removal was sustained for 20 months (approximately 189 pore volumes) in the stimulated column under sulfate- and Fe(III)-reducing conditions. Less apparent microbial activity and only minor removal of U(VI) and Tc(VII) were observed in the control. Sequential sediment extractions and XANES spectra confirmed that U(IV) was present in the stimulated column, although U(IV) was also detected in the control; extremely low concentrations precluded detection of Tc(IV) in any sample. These results provide additional evidence that bio-immobilization may be effective for removing U and Tc from groundwater. However, long-term effectiveness of bio-immobilization may be limited by hydraulic conductivity reductions or depletion of bioavailable Fe(III).     

Oral exposure to polystyrene nanoparticles affects iron absorption

The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron transport in an in vitro model of the intestinal epithelium and an in vivo chicken intestinal loop model. Intestinal cells that are exposed to high doses of nanoparticles showed increased iron transport due to nanoparticle disruption of the cell membrane. Chickens acutely exposed to carboxylated particles (50?nm in diameter) had a lower iron absorption than unexposed or chronically exposed birds. Chronic exposure caused remodelling of the intestinal villi, which increased the surface area available for iron absorption. The agreement between the in vitro and in vivo results suggests that our in vitro intestinal epithelium model is potentially useful for toxicology studies.     

Empirical Approach for Determining Ultimate FRP Strain in FRP-Strengthened Concrete Beams

The flexural capacity of concrete beams can be efficiently and effectively improved through bonding fiber-reinforced plastic (FRP) plates to the tensile side. Failure of the strengthened member often occurs through debonding of the FRP from the concrete substrate. If the ultimate FRP strain at debonding failure is known, the moment capacity of the member can be obtained through a simple section analysis. In the American Concrete Institute (ACI) Design Guideline, simple empirical equations are proposed to find the ultimate FRP strain in terms of the FRP stiffness alone. However, when the proposed equations are compared to experimental data, a very large scatter is observed, indicating that the effect of other parameters cannot be neglected. In the present investigation, a new empirical approach to obtain the FRP debonding strain is developed. With a comprehensive experimental database of 143 tests, a neural network relating the ultimate FRP strain to various geometric and material parameters is trained and validated. Using the validated network, an empirical design curve and several correction equations are generated to provide a simple means to find the debonding strain in practical design. Through use of the chart and equations, the calculated ultimate failure moments for the 143 tests in our database are found to be in good agreement with experimental results. The applicability of the new empirical approach to the failure prediction of strengthened members is thus demonstrated.