Ammonia synthesis enhanced by magnesium chloride absorption

Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl₂. The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl₂ salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl₂ than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1364–1371, 2015     

Issues in the use and interpretation of discriminant analysis.

Reviews the 2 problems for which a discriminant analysis is used—separation and classification. Issues related to the use and interpretation of a discriminant analysis are those pertaining to (a) distinguishing between a linear discriminant function and a linear classification function, (b) misusing stepwise discriminant analysis programs, (c) ordering variables and selecting variable subsets, (d) choosing a classification rule, (e) estimating true classification hit rates, (f) assessing classification accuracy, and (g) examining and using classification results. Most of these issues deal with information available from package discriminant analysis computer programs. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microvascular injury in reperfused infarcted myocardium: noninvasive assessment with contrast-enhanced echoplanar magnetic resonance imaging

OBJECTIVES: The purpose of this study was to measure the accumulation of labeled albumin and to visualize its distribution pattern in reperfused infarcted myocardium as a function of time between onset of reperfusion and administration of the tracer. BACKGROUND: Myocardial microvascular injury leads to leakage of albumin from the intravascular space. Quantitative measurements of GdDTPA-albumin with inversion recovery echoplanar imaging (IR-EPI) may allow noninvasive monitoring of microvascular injury. METHODS: After 1 h of coronary artery occlusion, 56 rats were injected with GdDTPA-albumin or 123I-GdDTPA-albumin either immediately before reperfusion or 1/2, 1 or 24 h after reperfusion. GdDTPA-albumin in blood, normal myocardium and reperfused infarction was dynamically measured with IR-EPI during 1 h postinjection (PI). Autoradiograms were obtained at 15 min PI. Accumulation of labeled albumin in myocardium was expressed as the ratio of myocardial to blood content. RESULTS: In normal myocardium, the ratio of changes of relaxation rate-ratio (deltaR1-ratio) was 0.12+/-0.01 and did not change over 1 h. In reperfused infarction, however, the deltaR1-ratio increased after administration. Animals given GdDTPA-albumin before reperfusion exhibited fastest accumulation (deltaR1-ratio 15 min PI: 0.56+/-0.03) and essentially homogeneous distribution. The accumulation was slower when administered at 1/2, 1 and 24 h after reperfusion (deltaR1-ratios 15 min PI: 0.39+/-0.03; 0.31+/-0.04; 0.16+/-0.01; p < 0.001 compared to administration before reperfusion). Moreover, the tracer accumulated predominantly in the periphery of the injury zone. CONCLUSIONS: Amount and distribution pattern of labeled albumin in reperfused infarction are modulated by duration of reperfusion. The accumulation of GdDTPA-albumin can be quantified by IR-EPI. Thus, IR-EPI may be useful to noninvasively monitor myocardial microvascular injury in reperfused infarction.     

Multivariate analysis versus multiple univariate analyses.

The argument for preceding multiple analysis of variance ({anovas}) with a multivariate analysis of variance ({manova}) to control for Type I error is challenged. Several situations are discussed in which multiple {anovas} might be conducted without the necessity of a preliminary {manova}. Three reasons for considering multivariate analysis are discussed: to identify outcome variable system constructs, to select variable subsets, and to determine variable relative worth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ammonia absorption at haber process conditions

The kinetics of ammonia absorption into magnesium chloride is measured as ammonia pressure change in the temperature range 170‐430^°C. The actual pressure minus that at equilibrium drops quickly, with a half life of less than a minute. It varies with the square‐root of time, suggesting diffusion limited absorption. The diffusion coefficient of ammonia in solid magnesium chloride inferred from these data is on the order 10^?11‐10^?13 cm²/s, considerably faster than many solid‐phase diffusivities. While optical microscopy and BET surface area experiments indicate recrystallization and agglomeration of the absorbent at ammonia synthesis temperatures, the absorption rate remains high. The dependence of absorption rate on temperature, particle size and the presence of a silica support is also investigated. The results suggest both improved ammonia separation and ways to develop high‐conversion, small‐scale, multifunctional ammonia synthesis reactors. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Optimale Finanzierung von Ein- und Zweifamilienhäusern

Zusammenfassung Ein Schwerpunkt privater Finanzierungsprobleme ist die Finanzierung von Wohnungseigentum. In der folgenden Untersuchung wird zunächst ein gemischt-ganzzahliges Modell zur Ermittlung der optimalen Finanzierung von Ein- und Zweifamilienhäusern bzw. Eigentumswohnungen kurz beschrieben. Anhand zahlreicher Simulationsläufe wird der Einfluß der Variation des Eigenkapitaleinsatzes und der Überschußbeteiligung auf die optimale Finanzierungsstruktur analysiert.

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Summary The main point of Personal Finance is the financing of proprietor's own used single-unit or doubleunit dwellings respectively owner-occupied apartments. In the following examination a mixed-integer programme for the determination of the optimum financing-mix for home construction is being developed shortly. By means of numeruous simulation tests the influence of varying capital resources of the home owner and the surplus resulting out of private life insurances upon the optimum financing structure is being analysed.

     

Chemical Defenses (Glucosinolates) of Native and Invasive Populations of the Range Expanding Invasive Plant Rorippa austriaca

Due to global warming, species are expanding their range to higher latitudes. Some range expanding plants have become invasive in their new range. The Evolution of Increased Competitive Ability (EICA) hypothesis and the Shifting Defense Hypothesis (SDH) predict altered selection on plant defenses in the introduced range of invasive plants due to changes in herbivore pressures and communities. Here, we investigated chemical defenses (glucosinolates) of five native and seven invasive populations of the Eurasian invasive range expanding plant, Rorippa austriaca. Further, we studied feeding preferences of a generalist and a specialist herbivore among the populations. We detected eight glucosinolates in the leaves of R. austriaca. 8-Methylsulfinyloctyl glucosinolate was the most abundant glucosinolate in all plants. There were no overall differences between native and invasive plants in concentrations of glucosinolates. However, concentrations among populations within each range differed significantly. Feeding preference between the populations by a generalist herbivore was negatively correlated with glucosinolate concentrations. Feeding by a specialist did not differ between the populations and was not correlated with glucosinolates. Possibly, local differences in herbivore communities within each range may explain the differences in concentrations of glucosinolates among populations. Little support for the predictions of the EICA hypothesis or the SDH was found for the glucosinolate defenses of the studied native and invasive R. austriaca populations.     

Mapping invasive Phragmites australis in the coastal Great Lakes with ALOS PALSAR satellite imagery for decision support

The invasive variety of Phragmites australis (common reed) forms dense stands that can cause negative impacts on coastal Great Lakes wetlands including habitat degradation and reduced biological diversity. Early treatment is key to controlling Phragmites, therefore a map of the current distribution is needed. ALOS PALSAR imagery was used to produce the first basin-wide distribution map showing the extent of large, dense invasive Phragmites-dominated habitats in wetlands and other coastal ecosystems along the U.S. shore of the Great Lakes. PALSAR is a satellite imaging radar sensor that is sensitive to differences in plant biomass and inundation patterns, allowing for the detection and delineation of these tall (up to 5 m), high density, high biomass invasive Phragmites stands. Classification was based on multi-season ALOS PALSAR L-band (23 cm wavelength) HH and HV polarization data. Seasonal (spring, summer, and fall) datasets were used to improve discrimination of Phragmites by taking advantage of phenological changes in vegetation and inundation patterns over the seasons. Extensive field collections of training and randomly selected validation data were conducted in 2010–2011 to aid in mapping and for accuracy assessments. Overall basin-wide map accuracy was 87%, with 86% producer's accuracy and 43% user's accuracy for invasive Phragmites. The invasive Phragmites maps are being used to identify major environmental drivers of this invader's distribution, to assess areas vulnerable to new invasion, and to provide information to regional stakeholders through a decision support tool.