The use of remotely sensed data to detect channel hydromorphology; River Tummel,Scotland

Colour aerial photography and multi‐spectral imagery acquired from airborne platforms for the River Tummel, Scotland, was used in conjunction with field survey to assess the feasibility of monitoring hydromorphology and human alteration within the river corridor. The study was undertaken to investigate the possibility of remotely sensing the physical status of a nation's rivers at the national scale to comply with the requirement of the European Water Framework Directive. Visual assessment and unsupervised and supervised automated classifications of the imagery were undertaken and compared with field survey data. In the absence of overhanging vegetation canopies most features above the water line of interest were visible on the imagery. Below the water line, morphology and substrate composition together with bank materials on vertically cut banks are less easily detected. The overall accuracy of automated classification procedures, compared to field survey, was 60% for the colour aerial photography and 68% for the multi‐spectral imagery. Supervised classification was superior to unsupervised classification procedures. Sun glint on water surfaces and shadows caused by high banks, trees and buildings were observed as the cause of most misclassification of features. Overall, the study demonstrates that remotely sensed digital imagery has the potential to allow panoptic mapping of river hydromorphology and human impacts. The possibilities and constraints, in light of the findings of this study, are discussed. In the context of new legislation which requires environmental protection agencies to have robust tools for monitoring the physical status, as part of meeting the objective of good ecological status, of rivers across an entire nation, remote sensing appears to provide a way forward. Copyright © 2004 John Wiley & Sons, Ltd.     

Reaction engineering studies of methane coupling in fluidised-bed reactors

The oxidative coupling of methane has been conducted in 30 and 60mm dia. fluidised-bed reactors. Methane conversions as high as 40% were achieved at isothermal conditions using methane/oxygen mixtures without diluents. At the same contact time the two reactors had similar selectivities to hydrocarbons. At 850°C the hydrocarbon selectivity decreased dramatically with increasing contact time but this effect was much less severe at lower temperatures. Axial gas concentration profiles through the catalyst bed in the 60mm reactor indicated that at 850°C there was a rapid consumption of oxygen and formation of products in the bottom section of the bed followed by a net loss of hydrocarbon in the oxygen-free zone. This loss was due to carbon formation on the catalyst which was circulated back to the oxygen-containing zone of the bed where the carbon was combusted.     

Evolution of silicon bulk lifetime during III–V‐on‐Si multijunction solar cell epitaxial growth

The evolution of Si bulk minority carrier lifetime during the heteroepitaxial growth of III–V on Si multijunction solar cell structures via metal‐organic chemical vapor deposition (MOCVD) has been analyzed. In particular, the impact on Si lifetime resulting from the four distinct phases within the overall MOCVD‐based III–V/Si growth process were studied: (1) the Si homoepitaxial emitter/cap layer; (2) GaP heteroepitaxial nucleation; (3) bulk GaP film growth; and (4) thick GaAs_yP_1‐y compositionally graded metamorphic buffer growth. During Phase 1 (Si homoepitaxy), an approximately two order of magnitude reduction in the Si minority carrier lifetime was observed, from about 450 to ≤1 µs. However, following the GaP nucleation (Phase 2) and thicker film (Phase 3) growths, the lifetime was found to increase by about an order of magnitude. The thick GaAs_yP_1‐y graded buffer was then found to provide further recovery back to around the initial starting value. The most likely general mechanism behind the observed lifetime evolution is as follows: lifetime degradation during Si homoepitaxy because of the formation of thermally induced defects within the Si bulk, with subsequent lifetime recovery due to passivation by fast‐diffusing atomic hydrogen coming from precursor pyrolysis, especially the group‐V hydrides (PH₃, AsH₃), during the III–V growth. These results indicate that the MOCVD growth methodology used to create these target III–V/Si solar cell structures has a substantial and dynamic impact on the minority carrier lifetime within the Si substrate. Copyright © 2015 John Wiley & Sons, Ltd.     

Density,production, and survival of walleye (Sander vitreus) eggs in the Muskegon River,Michigan

Walleye (Sander vitreus) is an important sport fish in the Great Lakes that is experiencing low reproductive success after severe population declines starting in the late 1940s. In the Muskegon River, Michigan, natural reproduction of walleyes remains low and is largely supplemented by stocking. To determine factors influencing walleye reproductive success in the Muskegon River, we estimated walleye egg survival using insitu egg incubators covered with nitex screening (2003–2004) and estimated density and survival of fertilized eggs caught on furnace filter traps across different substrate types (2005–2006). We compared physical habitat suitability for walleye eggs under high and low flow scenarios. Density of walleye eggs was highest in regions of gravel/cobble substrates. Egg survival was higher in egg incubators (24–49.5%) than on furnace filter traps (2.0%), suggesting predation is an important source of walleye egg mortality in the Muskegon River. Cold water temperatures that extended developmental stage durations may also be an important source of egg mortality. The dynamic habitat suitability model predicted low suitability for eggs due to poor temperature and velocity conditions. Despite low egg survival rates, 40 million to 1 billion eggs were estimated to hatch. The low natural reproduction of walleyes in the Muskegon River is likely due to a combination of low walleye egg survival and failure of walleye larvae to reach their nursery grounds in Muskegon Lake.     

Preparation and properties of bisphenol A polyetherketoneketone based phthalonitrile resins

A promising high temperature phthalonitrile (PN) resin composed of a polyetherketoneketone (PEKK) core bridged by two bisphenol A linkers and end capped with PN groups is presented. This PEKK-PN resin was characterized via differential scanning calorimetry, thermogravimetric analysis, proton nuclear magnetic resonance spectroscopy, scanning electron microscopy, dynamic mechanical analysis, attenuated total reflection Fourier transform infrared, and rheometry. The PEKK-PN resin was evaluated with two different compositions containing 1) 70:30 PEKK-PN to bisphenol A PN (n = 0) and 2) pure PEKK-PN. The 70:30 PEKK-PN resin was mixed with bis[4-(3-aminophenoxy)phenyl]sulfone and exhibited a melt viscosity of 271 cP, much lower than the 657 cP viscosity of the pure PEKK-PN mixture. Void-free PEKK-PN polymers were easily prepared by degassing and curing up to 380°C, resulting in fully crosslinked networks exhibiting thermal stability above 500°C and a 75% char yield. Additionally, the cured PEKK-PN polymer samples displayed good mechanical integrity retaining 50% stiffness at 300°C. This combination of properties suggests these new PEKK-PN resins are excellent materials for high temperature thermosets in composite applications.     

Are toxicological responses in laboratory (inbred) zebrafish representative of those in outbred (wild) populations? - A case study with an endocrine disrupting chemical

Laboratory animals tend to be more inbred and less genetically diverse than wild populations, and thus may differ in their susceptibility to chemical stressors. We tested this hypothesis by comparing the responses of related inbred (theoretical inbreeding F(IT) = n + 0.25) and outbred (F(IT) = n) zebrafish (Danio rerio) WIK/Wild family lines to an endocrine disrupting chemical, clotrimazole. Exposure of inbred and outbred zebrafish to 2.9 μg clotrimazole/L had no effect on survival, growth, or gonadal development. Exposure of both lines to 43.7 μg clotrimazole/L led to male-biased sex ratios compared with controls (87% versus 55% and 92% vs 64%, for inbred and outbred males, respectively), advanced germ cell development, and reduced plasma 11-ketotestosterone concentrations in males. However, outbred males (but not inbred males) developed testis that were more than twice the weight of controls, which corresponded with a proliferation of Leydig cells and maintenance of the expression (rather than down-regulation occurring in inbreds) of gonadal aromatase (cyp19a1a) and insulin-like growth factor (igf1). Our results illustrate that the effects of an endocrine disrupting chemical (clotrimazole) on some end points (here testis development) can differ between inbred and outbred zebrafish. This highlights the need for reporting pedigree/genetic information and consistency in the responses of laboratory animals (e.g., by using model compounds as positive controls).     

Relative potencies and combination effects of steroidal estrogens in fish

The natural steroids estradiol-17beta (E2) and estrone (E1) and the synthetic steroid ethynylestradiol-17alpha (EE2) have frequently been measured in waters receiving domestic effluents. All of these steroids bind to the estrogen receptor(s) and have been shown to elicit a range of estrogenic responses in fish at environmentally relevant concentrations. At present, however, no relative potency estimates have been derived for either the individual steroidal estrogens or their mixtures in vivo. In this study the estrogenic activity of E2, E1, and EE2, and the combination effects of a mixture of E2 and EE2 (equi-potent fixed-ratio mixture), were assessed using vitellogenin induction in a 14-day in vivo juvenile rainbow trout screening assay. Median effective concentrations, relative to E2, for induction of vitellogenin were determined from the concentration-response curves and the relative estrogenic potencies of each of the test chemicals calculated. Median effective concentrations were between 19 and 26 ng L(-1) for E2, 60 ng L(-1) for E1, and between 0.95 and 1.8 ng L(-1) for EE2, implying that EE2 was approximately 11 to 27 times more potent than E2, while E2 was 2.3 to 3.2 times more potent than E1. The median effective concentration, relative to E2, for the binary mixture of E2 and EE2 was 15 ng L(-1) (comprising 14.4 ng L(-1) E2 and 0.6 ng L(-1) EE2). Using the model of concentration addition it was shown that this activity of the binary mixture could be predicted from the activity of the individual chemicals. The ability of each individual steroid to contribute to the overall effect of a mixture, even at individual no-effect concentrations, combined with the high estrogenic potency of the steroids, particularly the synthetic steroid EE2, emphasizes the need to consider the total estrogenic load of these chemicals in our waterways.     

Interactions of refractory materials with molten gasifier slags

The current study focuses on the analysis of sessile-drop interfacial reactions between two synthetic slags (based on average ash chemistries of coal and petcoke feedstock) and two refractory materials (90 wt% Cr₂O₃-10 wt% Al₂O₃ and 100 wt% Al₂O₃), using a Confocal Scanning Laser Microscope (CSLM). Ground slag samples (less than 325 mesh) were placed at specific microstructure locations on refractory substrates and heated to 1500 °C in an atmosphere of CO/CO₂ gas mixture (volume ratio = 1.8), using a gold-image heating chamber. Cross-sections of the slag/refractory interface indicated unique slag penetration into preferred areas of the refractory and grain dissolution into the slag which promoted spalling of the refractory. Initially, the slag attacked both grain boundaries and fine microstructure areas, freeing alumina grains into the slag. The formation of VO_x-based crystalline material in the petcoke slag was found to alter the liquid composition. Chemical spalling of Cr-containing crystal layer also facilitated degradation of the refractory.     

Revisiting the Worksite in Worksite Health Campaigns: Evidence From a Multisite Organ Donation Campaign

This article advances the beginnings of a general theory of organizational features to aid in understanding why health campaigns that work well in one organization may be ineffectual in another organization. The physical, social, and information structures of organizations are theorized to create an interaction environment that is distinct to each organization and that influences health campaigns. To test this argument, an organ donation campaign was conducted in 46 organizations. Multilevel modeling yielded mixed findings. Physical structure was negatively associated with signing an organ donor card. Social structure and information structure were positively associated with communication with coworkers about donation and communicative peer influence. Industry type was positively associated with knowledge change.