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We report a sequent phase transition using high-resolution synchrotron x-ray scattering in a single crystal Nd1/2Sr1/2MnO3. By measuring the peak profile of Bragg reflections, upon cooling, we observed an increase in the width of the Bragg reflections around the Curie temperature (252 K) corresponding to the transition from a paramagnetic to a ferromagnetic state. Below approximately 200 K, dramatic changes in the width and integrated intensity were observed. Changes continued until the formation of charge ordering with q=(12,0,0) at TCO=152 K. This charge ordering was observed to be the first order transition with a large hysteresis width of 10 K. This sequent transition is understood by the formation of different magnetic domains at different temperature ranges as that observed by neutron powder diffraction. [ABSTRACT FROM AUTHOR]

Globally, the finfish aquaculture industry has experienced a decline in social acceptance, as the industry has been linked to coastal and marine environmental impacts. The causality, magnitude and intensity of these impacts are contested and controversial. To address these social concerns and perceptions, new lower-impact forms of production have been integrated in planning processes for the expansion of the salmon industry. This paper identifies a range of stakeholder views on coastal and marine ecosystem services associated with the expansion of salmon aquaculture using lower-impact forms of production in Tasmania, Australia. Stakeholder surveys combined with Q methodology interviews were used to capture stakeholders' 'subjectivities' or perspectives—described here as 'preferences'. The application of Q methodology identified three factors or perspectives—'utilitarian ecological', 'ecological primacy' and 'recreational amenity'—which explain the majority of the variance in stakeholder preferences. The 'utilitarian ecological' label accounted for the largest cluster of stakeholders' preferences, while the 'ecological primacy' and 'recreational amenity' perspectives accounted for small subsets of stakeholder preferences. Q methodology was an effective approach for identifying the range of stakeholder preferences for and the relative importance of ecosystem services in these coastal and marine environs. Environmental attributes such as seabed health and water quality were identified as being the most important regulating and supporting coastal and marine ecosystem services, followed by the subsequent flow of benefits to regional communities through employment in the Q results. [ABSTRACT FROM AUTHOR]

The crystal structure of deuterated benzene has been investigated over the complete temperature range 4–280 K. Our results are in excellent agreement with previous studies, recorded at a limited number of temperatures, and display a smooth variation of the lattice parameters over the complete temperature range. No evidence of the suggested low-temperature phase transitions, or marked premelting effects have been found. Detailed measurements of the lattice parameters close to the melting point display an anomalous behavior of the b lattice parameter and the orientation of the molecules which is believed to be evidence of a disordering transition at temperatures above the melting point. [ABSTRACT FROM AUTHOR]

Extensive molecular dynamics (MD) simulations are reported for benzene-d6, based on the potential of Karlström et al. [J. Am. Chem. Soc. 105, 3777 (1983)], linearly rescaled. Three phenomena have been identified as a function of temperature, a solid state structural phase transition, a lattice instability, and melting. The simulations clarify that the first two phenomena are distinct from premelting; they rationalize some of our recent experimental data, and lead to a suggestion for further experiments to substantiate these phenomena. Rescaling the ab initio potential gave lattice parameters and an internal energy in very good accord with experiment across a wide temperature range. The MD lattice instability at 335 K was shown not to be true melting, the melting point being found at 272 K using a system with free surfaces. This result, the latent heat and volume discontinuity at melting, and the thermal motion amplitudes were all found to be in very good agreement with experiment. The first high-pressure phase of benzene was also successfully modeled by the potential, giving excellent values for the structural parameters. A MD result not found in experiment is a disordering transition in which the distinction between the orientations of pairs of molecules in the unit cell is lost. Experimental data appears to show that the same effect would be seen in real benzene were the solid not to melt first. It has also been shown that the application of moderate pressures may make the transition more apparent experimentally. [ABSTRACT FROM AUTHOR]

Presents information on a study which described the contribution of high-resolution x-ray diffraction and x-ray reflectivity measurements in characterizing a GaAs/AlInAs/InP hetero-epitaxially growth single quantum well structure. Experimental details; Theory and analysis of the results; Conclusions.

Examines the application of high-resolution triple-crystal x-ray techniques in analyzing the high-temperature superconducting thin films of gadolinium-barium-copper-oxygen grown in situ by direct current magnetron sputtering onto substrates of LaAlO[sub3] and SrTiO[sub3]. Preparation of the thin films; Experimental technique of the study; Results of the measurements with pyrolytic graphite monochromator and analyzer crystals.

Most dental resin composite restorations are replacements for failing restorations. Degradation of the restoration-tooth margins by cariogenic bacteria results in recurrent caries, a leading cause for restoration failure. Incorporating antimicrobial agents in dental adhesives could reduce interfacial bacterial count and reduce recurrent caries rates, inhibit interfacial degradation, and prolong restoration service life, while minimizing systemic exposure. Direct addition of antimicrobial compounds into restorative materials have limited release periods and could affect the integrity of the material. Attempts to incorporate antimicrobial within mesoporous silica nanoparticles showed theoretical promise due to their physical robustness and large available internal volume, yet yielded short-term burst release and limited therapeutic payload. We have developed novel broad-spectrum antimicrobial drug-silica particles co-assembled for long-term release and high payload incorporated into dental adhesives. The release of the drug, octenidine dihydrochloride, is modulated by the oral degradative environment and mathematically modeled to predict effective service life. Steady-state release kills cariogenic bacteria, preventing biofilm formation over the adhesive surface, with no toxicity. This novel material could extend dental restoration service life and may be applied to other long-term medical device-tissue interfaces for responsive drug release upon bacterial infection. Statement of Significance This study describes a novel dental adhesive that includes a broad-spectrum antimicrobial drug-silica co-assembled particles for long-term antimicrobial effect. The release of the drug, octenidine dihydrochloride, is modulated by the oral degradative environment and mathematically modeled to predict effective release throughout the service life of the restoration. Steady-state drug-release kills caries-forming bacteria, preventing biofilm formation over the adhesive surface, without toxicity. This novel material could extend dental restoration service life and may be applied to other long-term medical device-tissue interfaces for responsive drug release upon bacterial infection. Since recurrent cavities (caries) caused by bacteria are the major reason for dental filling failure, this development represents a significant contribution to the biomaterials field in methodology and material performance. [ABSTRACT FROM AUTHOR]

Growth in offshore blue economies is predicted to accelerate as emerging food and energy production industries look to expand into these environments. Operating in novel environments for these industries inherently fosters uncertainty in outcomes generated by a complex suite of hazards, some of which are unknown prior to deployment. Faced with such uncertainty, a precautionary, flexible, and cross-disciplinary (integrated) approach is recommended to optimize the potential for hazards to be identified in a timely, comprehensive, and robust manner, and mitigated. However, relevant disciplines – such as aquaculture production, marine engineering, and marine renewable energy design, and associated interactions with society and the environment – often evolve with their siloed techniques and lexicons. Here we first provide an overview of selected discipline-specific approaches to hazard analysis as a first step in a pathway that can generate a holistic synthesis of hazards to and from multiple emerging sectors in novel environments. Despite challenges of applying these individual methods to cross-disciplinary projects for emerging industries, we then identify where disciplines share methodological approaches and where opportunities exist to develop integrated methods. With a growing focus on sustainable economic growth and optimizing the use of ocean space through multi-use, our review highlighted that the emerging offshore Blue Economy could benefit from the development of a flexible, integrated approach to identify and assess hazards in a comprehensive, robust and useful manner for successful planning, development, and operations. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) is a technologically important and complex quaternary semiconductor and a highly promising material for the absorber layer in sustainable thin film solar cells. Its photovoltaic performance is currently limited by low open-circuit voltage, thought to be due to a range of point defects such as disorder between the copper and zinc lattice sites. This is the highest-resolution neutron diffraction study reported for CZTS, which unambiguously identifies the crystal symmetry and accurately quantifies precise values for the disorder on all cation symmetry sites as a function of temperature. Two samples of CZTS were fabricated by solid state reaction and their compositions were measured by inductively-coupled plasma mass spectroscopy, which identified significant tin loss during growth, leaving the samples Sn-poor, Cu-rich and Sn-poor, Zn-rich respectively. Both samples were found exclusively to adopt the tetragonal kesterite crystal structure with significant cation disorder, which is investigated in detail over the range 4–1275 K. Importantly, and in contrast to previous reports, the 2a Wyckoff site shows disorder equal to or greater than the 2c site. The order–disorder phase transition was observed at different temperatures for the two compositions, 489 and 501 K respectively, lower than previously reported. The kesterite–sphalerite transition was observed between 1250 and 1275 K for the Sn-poor, Cu-rich sample, significantly higher than previously reported. These results provide new insights into the high levels of disorder present in CZTS and confirm that composition and cation disorder have a significant effect on the phase transition mechanism. This work will enable the development of routes to the fabrication of higher-efficiency photovoltaic devices. [ABSTRACT FROM AUTHOR]