Antiferromagnetic Coupling of Pr0.9RE0.1Ni (RE = Tb, Dy, Ho) Single Crystals

Magnetization and specific heat measurements were carried out on Pr0.9RE0.1Ni (RE = Tb,Dy, and Ho) single crystals. Spin rearrangements were observed along the c-axis ofsingle crystals with relatively small critical fields, Bc = 6.8, 4.0 and 2.6 T for RE = Tb,Dy and Ho, respectively. The magnetic phase transition temperatures, TM, were extracted from the specific heat data: TM = 22.7, 19.6 and 18.3 K with RE = Tb, Dy and Ho, respectively. The observed Bc values were used to estimate the heterogeneous (Pr-RE) exchange strength, and then calculate expected TM values, which were found to be close to the experimental ones. The present results of Bc and TM, together with the previous ones of Pr0.9Gd0.1Ni, were found to be consistent with the de Gennes rule

Time Dependent Magnetization of an Al-1.6%Mg₂Si Alloy

New observations of time dependent magnetization of an Al-1.6%Mg2Si alloy over a range of constant temperatures between 250 K and 310 K are presented. The post solution heat treatment time variations of magnetization at 300 and 310 K increased with time out to about 1300 minutes, whereas those at 280 and 290 K showed minima around 150 and 50 minutes, respectively. The magnetization at 250 K initially decreased slightly and then became constant with time. The observed time variations of magnetization are explained in terms of clustering reactions of the Mg, Si and vacancies

Early Stage Clustering Behavior in Al-Mg-Si Alloys Observed via Time Dependent Magnetization

Time dependent magnetization of Al-0.67 at.%Mg-0.73 at.%Si, Al-1.07 at.%Mg-0.33 at.%Si and Al-1.07 at.%Mg-0.53 at.%Si alloys are presented over a range of constant temperatures between 250 and 320 K. The magnetization vs. time curves for the samples show minima for temperatures near 290 K. The observed times at which the magnetization minima occur were found to depend on both the solute concentrations and the measurement temperatures. From these results the activation energies from the Si-rich clustering stage to the Mg-Si co-clustering stage were extracted. The deduced activation energies were found to be comparable to those from the positron annihilation measurements, depending on the solute concentrations

Laser-Ablated Vortex Fluidic-Mediated Synthesis of Superparamagnetic Magnetite Nanoparticles in Water Under Flow

ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposesSelective formation of only one iron oxide phase is a major challenge in conventional laser ablation process, as is scaling up the process. Herein, superparamagnetic single-phase magnetite nanoparticles of hexagonal and spheroidal-shape, with an average size of ca. 15 nm, are generated by laser ablation of bulk iron metal at 1064 nm in a vortex fluidic device (VFD). This is a one-step continuous flow process, in air at ambient pressure, with in situ uptake of the nanoparticles in the dynamic thin film of water in the VFD. The process minimizes the generation of waste by avoiding the need for any chemicals or surfactants and avoids time-consuming purification steps in reducing any negative impact of the processing on the environment.The authors gratefully acknowledge the financial support from the Australia Research Council and the Government of South Australia; also the expertise, equipment, and support provided by the Australian Microscopy and Microanalysis Research Facility (AMMRF) and the Australian National Fabrication Facility (ANFF) at the South Australian nodes of the AMMRF and ANFF under the National Collaborative Research Infrastructure Strategy

A compendium of ecological knowledge for restoration of freshwater fishes in Australia’s Murray–Darling Basin

Many freshwater fishes are imperilled globally, and there is a need for easily accessible, contemporary ecological knowledge to guide management. This compendium contains knowledge collated from over 600 publications and 27 expert workshops to support the restoration of 9 priority native freshwater fish species, representative of the range of life-history strategies and values in south-eastern Australia’s Murray–Darling Basin. To help prioritise future research investment and restoration actions, ecological knowledge and threats were assessed for each species and life stage. There is considerable new knowledge (80% of publications used were from the past 20 years), but this varied among species and life stages, with most known about adults, then egg, juvenile and larval stages (in that order). The biggest knowledge gaps concerned early life stage requirements, survival, recruitment, growth rates, condition and movements. Key threats include reduced longitudinal and lateral connectivity, altered flows, loss of refugia, reductions in both flowing (lotic) and slackwater riverine habitats, degradation of wetland habitats, alien species interactions and loss of aquatic vegetation. Examples and case studies illustrating the application of this knowledge to underpin effective restoration management are provided. This extensive ecological evidence base for multiple species is presented in a tabular format to assist a range of readers