Evolution of InAs branches in InAs/GaAs nanowire heterostructures

Branched nanowireheterostructures of InAs∕GaAs were observed during Au-assisted growth of InAs on GaAsnanowires. The evolution of these branches has been determined through detailed electron microscopy characterization with the following sequence: (1) in the initial stage of InAsgrowth, the Au droplet is observed to slide down the side of the GaAsnanowire, (2) the downward movement of Aunanoparticle later terminates when the nanoparticle encounters InAsgrowing radially on the GaAsnanowire sidewalls, and (3) with further supply of In and As vapor reactants, the Aunanoparticles assist the formation of InAs branches with a well-defined orientation relationship with GaAs∕InAs core/shell stems. We anticipate that these observations advance the understanding of the kink formation in axial nanowireheterostructures.The Australian Research Council is acknowledged for the financial support of this project. One of the authors M.P. acknowledges the support of an International Postgraduate Research Scholarship

The sustainability conundrum of fishmeal substitution by plant ingredients in shrimp feeds

Aquaculture is central in meeting expanding global demands for shrimp consumption. Consequently, increasing feed use is mainly responsible for the overall environmental impact of aquaculture production. Significant amounts of fishmeal are included in shrimp diets, causing dependency on finite marine resources. Driven by economic incentives, terrestrial plant ingredients are widely viewed as sustainable alternatives. Incremental fishmeal substitution by plant ingredients in shrimp feed was modeled and effects on marine and terrestrial resources such as fish, land, freshwater, nitrogen, and phosphorus were assessed. We find that complete substitution of 20–30% fishmeal totals could lead to increasing demand for freshwater (up to 63%), land (up to 81%), and phosphorus (up to 83%), while other substitution rates lead to proportionally lower impacts. These findings suggest additional pressures on essential agricultural resources with associated socio-economic and environmental effects as a trade-off to pressures on finite marine resources. Even though the production of shrimp feed (or aquafeed in general) utilizes only a small percentage of the global crop production, the findings indicate that the sustainability of substituting fishmeal by plant ingredients should not be taken for granted, especially since aquaculture has been one of the fastest growing food sectors. Therefore, the importance of utilizing by-products and novel ingredients such as microbial biomass, algae, and insect meals in mitigating the use of marine and terrestrial resources is discussed

A Turke turn'd Quaker: conversion from Islam to radical dissent in early modern England

The study of the relationship between the anglophone and Islamic worlds in the seventeenth century has been the subject of increas- ing interest in recent years, and much attention has been given to the cultural anxiety surrounding “Turning Turke”, conversion from Christianity to Islam, especially by English captives on the Barbary coast. Conversion in the other direction has attracted far less scrutiny, not least because it appears to have been far less com- mon. Conversion from Islam to any form of radical dissent has attracted no scholarship whatsoever, probably because it has been assumed to be non-existent. However, the case of Bartholomew Cole provides evidence that such conversions did take place, and examining the life of this “Turke turn’d Quaker” provides an insight into the dynamics of cross-cultural conversion of an exceptional kind

Mining employment scenarios for South Africa to 2024

AugustThis report was prepared for the HSRC and seeks to investigate potential employment in the South African mining industry. The paper focuses on: 1. An assessment of the rate and nature of investment in South Africa's mining industry. This necessarily has to be conducted on a commodity-specific basis and be based on global supply / demand scenarios and planned investments. 2. An assessment of the employment drivers in mining, how these relate to mining investment and in particular whether significant technological changes to mining methods amounting to greater mechanisation will be widely adopted. 3. An assessment of employment, incomes and occupational skills levels, which will be largely determined by the above investment and mining methods drivers. 4. An assessment of the inter-sectoral linkages between mining and upstream suppliers, side-stream (equipment, services and consumables) as well the impact on downstream industries

Relationship between European eel Anguilla anguilla infection with non-native parasites and swimming behaviour on encountering accelerating flow

The effect of Anguillicola crassus, Pseudodactylogyrus bini and Pseudodactylogyrus anguillae infection on the behaviour of downstream migrating adult European eels Anguilla anguilla as they encountered accelerating water velocity, common at engineered structures where flow is constricted (e.g. weirs and bypass systems), was evaluated in an experimental flume. The probability of reacting to, and rejecting, the velocity gradient was positively related to A. crassus larval, adult and total abundance. High abundance of Pseudodactylogyrus spp. reduced this effect, but A. crassus was the strongest parasitic factor associated with fish behaviour, and abundance was positively related to delay in downstream passage. Delayed downstream migration at hydraulic gradients associated with riverine anthropogenic structures could result in additional energetic expenditure for migrating A. anguilla already challenged by A. crassus infection

Novel growth phenomena observed in axial InAs/GaAs nanowire heterostructures.

Growth behavior in Axial InAs/GaAs nanowire heterostructures was observed as they have important applications in optoelectronics. The physical phenomena, which resulted in the failure of axial InAs nanowire growth on GaAs nanowires, was demonstrated. The vapor-liquid-solid (VPS) method was used for the growth of nanowire heterostructures. The changes in the growth directions of nanowires were studied by Transmission electron microscopy (TEM), which lead to the growth failure of InAs Axial growth on the GaAs nanowires. The catalyst used for the growth of the InAs/GaAs nanowires was gold. TEM investigations have determined that the initial InAs clustering at the edge of an Au/GaAs interface results in Au particles that are unbalanced with the GaAs surface and wetting between the Au and the GaAs nanowire sidewalls results in the downward growth of InAs, in which InAs nanowire sections have an epitaxial relationship with GaAs sections

Localization and chemical speciation of Pb in roots of Signal grass (Brachiaria decumbens) and Rhodes grass (Chloris gayana)

Lead (Pb) contamination of soils is of global importance but little is known regarding Pb uptake, localization, or the chemical forms in which Pb is found within plants, or indeed how some plants tolerate elevated Pb in the environment. Two grasses, signal grass (Brachiaria decumbens Stapf) (Pb-resistant) and Rhodes grass (Chloris gayana Kunth) (Pb-sensitive), were grown for 14 d in dilute nutrient solutions before examination of roots using transmission electron microscopy (TEM) to determine the distribution and speciation of Pb in situ. In both grasses, Pb was initially present primarily in the cytoplasm of rhizodermal and cortical cells before being sequestered within vacuoles as the highly insoluble (and presumably nontoxic) chloropyromorphite (Pb(5)(PO(4))(3)CI). In signal grass, Pb also accumulated within membranous structures (perhaps the Golgi apparatus), prior to apoplastic sequestration as chloropyromorphite. These findings suggest that the ability of signal grass to sequester insoluble Pb in the cell wall represents an additional and potentially important mechanism of Pb tolerance not possessed by the Pb-sensitive Rhodes grass

Novel growth phenomena observed in axial InAs/GaAs nanowire heterostructures

Growth behavior in Axial InAs/GaAs nanowire heterostructures was observed as they have important applications in optoelectronics. The physical phenomena, which resulted in the failure of axial InAs nanowire growth on GaAs nanowires, was demonstrated. Th