Misfit strain relaxation and dislocation formation in supercritical strained silicon on virtual substrates

Relaxation of strained silicon on 20% linear graded virtual substrates was quantified using high resolution x-ray diffraction and a defect etching technique. The thickness of strained silicon was varied between 10 and 180 nm. Relaxation was observed in layers below the critical thickness but increased to only 2% relaxation in the thickest layers even with annealings up to 950 °C. Cross-sectional transmission electron microscopy revealed stacking faults present in layers thicker than 25 nm, and nucleated 90° Shockley partial dislocations forming microtwins in the thickest layer. These features are implicated in the impediment of the relaxation process

The influence of flow discharge variations on the morphodynamics of a diffluence-confluence unit on a large river: Impacts of discharge variation on a diffluence-confluence unit

© 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd. Bifurcations are key geomorphological nodes in anabranching and braided fluvial channels, controlling local bed morphology, the routing of sediment and water, and ultimately defining the stability of their associated diffluence–confluence unit. Recently, numerical modelling of bifurcations has focused on the relationship between flow conditions and the partitioning of sediment between the bifurcate channels. Herein, we report on field observations spanning September 2013 to July 2014 of the three-dimensional flow structure, bed morphological change and partitioning of both flow discharge and suspended sediment through a large diffluence–confluence unit on the Mekong River, Cambodia, across a range of flow stages (from 13 500 to 27 000 m 3 s −1 ). Analysis of discharge and sediment load throughout the diffluence–confluence unit reveals that during the highest flows (Q = 27 000 m 3 s −1 ), the downstream island complex is a net sink of sediment (losing 2600 ± 2000 kg s −1 between the diffluence and confluence), whereas during the rising limb (Q = 19 500 m 3 s −1 ) and falling limb flows (Q = 13 500 m 3 s −1 ) the sediment balance is in quasi-equilibrium. We show that the discharge asymmetry of the bifurcation varies with discharge and highlight that the influence of upstream curvature-induced water surface slope and bed morphological change may be first-order controls on bifurcation configuration. Comparison of our field data to existing bifurcation stability diagrams reveals that during lower (rising and falling limb) flow the bifurcation may be classified as unstable, yet transitions to a stable condition at high flows. However, over the long term (1959–2013) aerial imagery reveals the diffluence–confluence unit to be fairly stable. We propose, therefore, that the long-term stability of the bifurcation, as well as the larger channel planform and morphology of the diffluence–confluence unit, may be controlled by the dominant sediment transport regime of the system. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

Analysis of the 2007/8 Defra Farm Business Survey Energy Module

Key points This study has delivered an invaluable baseline estimate of energy use and greenhouse gas (GHG) emissions on commercial farms in England. Energy use and GHG emissions associated with particular commodities were quantified and results broadly agreed with those derived by Life Cycle Assessment, but with much scatter in the environmental performance of farms.Direct energy use on farms was generally less that indirect (embedded) energy use, except for horticulture, which is dominated by heating fuel use. In contrast, most GHG emissions are incurred on farms, rather than as embedded emissions.Scatter in both environmental and economic performance underlies the somewhat disappointing finding of no clear positive link between farm financial performance and energy use or GHG emissions. However, the mere existence of these ranges shows that there is scope for improvement in both financial and environmental performance and that there is no apparent barrier for both to be achievable in harmony. The recording of such farm-level energy data is essential for the future, as it should enable improvements to be made in efficiency of energy use. The improved UK agricultural GHG inventory will depend on high quality energy data on agricultural activities. This study will be invaluable in identifying the level of detail needed. Future data requirements include: contractor work rates and fuel use per unit area and per unit time, fertiliser and pesticide use by brand name, enhanced output data, especially animal live weights, and horticultural produce recorded by weight rather than by value

Flow separation in meander bends.

Most investigations of river meanders have concentrated on classical bends that have a helical flow structure through the pool, which is carried through into the entrance of the next bend. However, it is known that flow separation can occur at the outer bank before the bend apex or at the inner bank after the apex and that this results in the breakdown of the classical flow model. Although some of the controls and the implications of flow separation are now known, the frequency of occurrence, threedimensional (3-D) flow structure, sediment dynamics, controls on separation presence, and full geomorphological implications are poorly understood. This thesis uses a combination of fieldwork and 3-D numerical flow modelling (computational fluid dynamics, CFD) to investigate meander bends where flow separation and recirculation zones are present. An initial reconnaissance survey of over 600 bends revealed that flow separation is common, being present in approximately 50% of bends. The survey also identified high bend angles of tum and the high angles of flow impingement onto the outer bank as important controls on the presence of separation. Investigations in a 22 bend sub-set indicated that expansions in channel width, breaks in bank-line curvature and the angle of inflow, as governed by upstream planform, were important in generating flow separation. Detailed fieldwork combined with validated and verified time-averaged CFD modelling in three bends with separation zones enabled identification and examination of the 3-D flow fields. The simulations reveal that the flow structure in bends with separation differs considerably from the classical flow model, with the helical motion found in classical bends being very intense in the bend entrance but dissipating at or just after the bend apex. The turbulent flow structures produced by the shear layer between the downstream and recirculating flow are also investigated in the field bends and attempts at modelling transient flow structures with large eddy simulation (LES) in a simple open channel flow expansion are detailed. The geomorphological, sedimentological, and ecological implications of both the time-averaged and the transient flow structures within the bends are examined and discussed

Extreme flood-driven fluvial bank erosion and sediment loads: direct process measurements using integrated Mobile Laser Scanning (MLS) and hydro-acoustic techniques: Direct measurement of flood-driven erosion using MLS and MBES

Copyright © 2016 John Wiley & Sons, Ltd. This methods paper details the first attempt at monitoring bank erosion, flow and suspended sediment at a site during flooding on the Mekong River induced by the passage of tropical cyclones. We deployed integrated mobile laser scanning (MLS) and multibeam echo sounding (MBES), alongside acoustic Doppler current profiling (aDcp), to directly measure changes in river bank and bed at high (~0.05 m) spatial resolution, in conjunction with measurements of flow and suspended sediment dynamics. We outline the methodological steps used to collect and process this complex point cloud data, and detail the procedures used to process and calibrate the aDcp flow and sediment flux data. A comparison with conventional remote sensing methods of estimating bank erosion, using aerial images and Landsat imagery, reveals that traditional techniques are error prone at the high temporal resolutions required to quantify the patterns and volumes of bank erosion induced by the passage of individual flood events. Our analysis reveals the importance of cyclone-driven flood events in causing high rates of erosion and suspended sediment transport, with a c. twofold increase in bank erosion volumes and a fourfold increase in suspended sediment volumes in the cyclone-affected wet season. Copyright © 2016 John Wiley & Sons, Ltd

Influence of light and temperature cycles on the expression of circadian clock genes in the mussel Mytilus edulis

Clock genes and environmental cues regulate essential biological rhythms. The blue mussel, Mytilus edulis, is an ecologically and economically important intertidal bivalve undergoing seasonal reproductive rhythms. We previously identified seasonal expression differences in M. edulis clock genes. Herein, the effects of light/dark cycles, constant darkness, and daily temperature cycles on the circadian expression patterns of such genes are characterised.Clock genes Clk, Cry1, ROR/HR3, Per and Rev-erb/NR1D1, and Timeout-like, show significant mRNA expression variation, persisting in darkness indicating endogenous control. Rhythmic expression was apparent under diurnal temperature cycles in darkness for all except Rev-erb. Temperature cycles induced a significant expression difference in the non-circadian clock-associated gene aaNAT. Furthermore, Suppression Subtractive Hybridisation (SSH) was used to identify seasonal genes with potential links to molecular clock function revealed numerous genes meriting further investigation. Understanding the relationship between environmental cues and molecular clocks is crucial in predicting the outcomes of environmental change on fundamental rhythmic processes

Agricultural Pea Waste as a Low-Cost Pollutant Biosorbent for Methylene Blue Removal: Adsorption Kinetics, Isotherm And Thermodynamic Studies

Biosorbents are an alternative pollutant adsorbent, usually sourced from waste biomass and requiring little to no treatment. This makes them cheaper than conventional adsorbents. In this paper, green pea (Pisum sativum) haulm was used as a biosorbent for the adsorption of methylene blue dye. The potential application of pea haulm as a biosorbent has not been investigated before. Characterisation using scanning electron microscopy, infrared spectroscopy and thermal gravitational analysis showed the surface to be coarse, detected functional groups important for adsorption and identified the composition of key biomass components. The effects of particle size, contact time, agitation, dosage, solution pH, temperature and initial dye concentration on the removal of MB by pea haulm were investigated. Using the data from these studies, the best fitting kinetic and isotherm models were found and the thermodynamic properties were identified. The maximum theoretical adsorption capacity was 167 mg/g, which was relatively high compared to other recent biosorbent studies. The pseudo-second-order adsorption kinetic and Freundlich adsorption isotherm models were the best fitting models. The biosorption process was exothermic and spontaneous at low temperatures. It was concluded that pea haulm was an effective adsorbent of methylene blue and could perhaps find application in wastewater treatment

Familiarity Breeds Contempt: Kangaroos Persistently Avoid Areas with Experimentally Deployed Dingo Scents

Background: Whether or not animals habituate to repeated exposure to predator scents may depend upon whether there are predators associated with the cues. Understanding the contexts of habituation is theoretically important and has profound implication for the application of predator-based herbivore deterrents. We repeatedly exposed a mixed mob of macropod marsupials to olfactory scents (urine, feces) from a sympatric predator (Canis lupus dingo), along with a control (water). If these predator cues were alarming, we expected that over time, some red kangaroos (Macropus rufous), western grey kangaroos (Macropus fuliginosus) and agile wallabies (Macropus agilis) would elect to not participate in cafeteria trials because the scents provided information about the riskiness of the area. Methodology/Principal Findings: We evaluated the effects of urine and feces independently and expected that urine would elicit a stronger reaction because it contains a broader class of infochemicals (pheromones, kairomones). Finally, we scored non-invasive indicators (flight and alarm stomps) to determine whether fear or altered palatability was responsible for the response. Repeated exposure reduced macropodid foraging on food associated with 40 ml of dingo urine, X = 986.75±3.97 g food remained as compared to the tap water control, X = 209.0±107.0 g (P0.5). Macropodids did not habituate to repeated exposure to predator scents, rather they avoided the entire experimental area after 10 days of trials (R2 = 83.8; P<0.001). Conclusions/Significance: Responses to urine and feces were indistinguishable; both elicited fear-based responses and deterred foraging. Despite repeated exposure to predator-related cues in the absence of a predator, macropodids persistently avoided an area of highly palatable food. Area avoidance is consistent with that observed from other species following repeated anti-predator conditioning, However, this is the first time this response has been experimentally observed among medium or large vertebrates 2 where a local response is observed spatially and an area effect is revealed over time

Microwave-Assisted Hydrothermal Carbonisation of Waste Biomass: The Effect of Process Conditions on Hydrochar Properties

Hydrochars are an alternative form of biochar produced by hydrothermal carbonisation (HTC), a potentially cheaper and greener method. In this paper, the effect of multiple variables on hydrochar properties was investigated. Waste biomass was converted to hydrochar via microwave-assisted hydrothermal carbonisation. The variables were temperature, solution ratio (water-biomass ratio), time, particle size, pH and acetone washing. The measured properties were yield, carbon, oxygen and ash content, higher heating value (HHV), carbon and energy recovery and dye and water adsorption. Feedstock significance was investigated using apple, wheat, barley, oat and pea straw. The investigation into this specific combination of variables and feedstock has not been done before. HTC increased carbon content (~60%), HHV (~24 MJ/kg) and water adsorption and reduced oxygen content and dye adsorption. Thermal analysis suggested hydrochars were not suitable for sequestration. Decreasing the solution ratio was the most significant factor in increasing yield, carbon recovery and energy yield. Increasing the temperature was the most significant factor in increasing carbon and decreasing oxygen content. This affected HHV, with higher temperatures producing a higher energy material, surpassing brown coal. Hydrochars produced at a high solution ratio, temperature and times showed the best carbonisation. Smaller particle size increased yield and carbonisation but increased ash content. Low solution pH increased carbon content, HHV and water adsorption but lowered yield, carbon recovery, energy yield, dye adsorption and oxygen and ash content. High pH increased ash content and dye adsorption but lowered yield, carbon recovery, energy yield and dye adsorption. Acetone decreased yield, carbon recovery, energy yield, carbon content and HHV but increased oxygen, ash content and dye and water adsorption. Barley biomass showed the highest yield and carbon recovery, and pea showed the highest energy yield and HHV. Apple showed the highest carbon content. All the hydrochars showed promise as solid fuels, a soil additive and a precursor for activated carbon but lacked high adsorption for pollutant adsorbents and stability for carbon sequestration