Spin correlations in Ca3Co2O6: A polarised-neutron diffraction and Monte Carlo study

We present polarised-neutron diffraction measurements of the Ising-like spin-chain compound Ca3Co2O6 above and below the magnetic ordering temperature TN. Below TN, a clear evolution from a single-phase spin-density wave (SDW) structure to a mixture of SDW and commensurate antiferromagnet (CAFM) structures is observed on cooling. For a rapidly-cooled sample, the majority phase at low temperature is the SDW, while if the cooling is performed sufficiently slowly, then the SDW and the CAFM structure coexist between 1.5 and 10 K. Above TN, we use Monte Carlo methods to analyse the magnetic diffuse scattering data. We show that both intra- and inter-chain correlations persist above TN, but are essentially decoupled. Intra-chain correlations resemble the ferromagnetic Ising model, while inter-chain correlations resemble the frustrated triangular-lattice antiferromagnet. Using previously-published bulk property measurements and our neutron diffraction data, we obtain values of the ferromagnetic and antiferromagnetic exchange interactions and the single-ion anisotropy.Comment: 10 pages, 7 figure

Hierarchy of exchange interactions in the triangular-lattice spin-liquid YbMgGaO4_{4}

The spin-1/2 triangular lattice antiferromagnet YbMgGaO$_{4}$ has attracted recent attention as a quantum spin-liquid candidate with the possible presence of off-diagonal anisotropic exchange interactions induced by spin-orbit coupling. Whether a quantum spin-liquid is stabilized or not depends on the interplay of various exchange interactions with chemical disorder that is inherent to the layered structure of the compound. We combine time-domain terahertz spectroscopy and inelastic neutron scattering measurements in the field polarized state of YbMgGaO$_{4}$ to obtain better microscopic insights on its exchange interactions. Terahertz spectroscopy in this fashion functions as high-field electron spin resonance and probes the spin-wave excitations at the Brillouin zone center, ideally complementing neutron scattering. A global spin-wave fit to all our spectroscopic data at fields over 4T, informed by the analysis of the terahertz spectroscopy linewidths, yields stringent constraints on $g$-factors and exchange interactions. Our results paint YbMgGaO$_{4}$ as an easy-plane XXZ antiferromagnet with the combined and necessary presence of sub-leading next-nearest neighbor and weak anisotropic off-diagonal nearest-neighbor interactions. Moreover, the obtained $g$-factors are substantially different from previous reports. This works establishes the hierarchy of exchange interactions in YbMgGaO$_{4}$ from high-field data alone and thus strongly constrains possible mechanisms responsible for the observed spin-liquid phenomenology

Selective Hydrogenation of Furfural in a Proton Exchange Membrane Reactor Using Hybrid Pd/Pd Black on Alumina

Conventional thermocatalytic hydrogenation employs high temperatures and pressures and often exhibits low selectivity toward desired products. Electrochemical hydrogenation can reduce energy input by operating at ambient conditions and improving process control and selectivity; however, electrocatalysts face stability and conductivity limitations. To overcome these obstacles, we physically mixed a traditional electrocatalyst (Pd black) with a hydrogenation‐active metal (Pd) supported on a conventional metal oxide support (alumina, Al2O3) and investigated electrochemical hydrogenation of furfural, a model biomass compound. Experiments were conducted in a proton exchange membrane (PEM) reactor, in which synthesized electrocatalysts were used as cathodes. Catalysts with Pd black and varying loadings of Pd on Al2O3 were used to determine the impact of hydrogen spillover on electrocatalytic hydrogenation mechanisms, selectivity, and rates. Observed hydrogenation rates and selectivities were linked to structural and compositional properties of the catalyst mixtures. Of the Pd black cathodes tested, 5 wt % Pd/Al2O3 exhibited production rates as high as pure Pd black and higher selectivity towards completely hydrogenated products. Improved selectivity and rates were attributed to a synergistic interaction between Pd black and 5 wt % Pd/Al2O3 in which Pd/Al2O3 increased the number of active sites, while Pd black provided stable conductivity.Breaking away from convention: The performance of hybrid cathodes, consisting of a traditional electrocatalyst (Pd black) with a hydrogenation‐active metal (Pd) supported on a conventional metal oxide support (Al2O3), is investigated using electrochemical hydrogenation of furfural in a proton exchange membrane reactor. Varying loadings of Pd on Al2O3 within the hybrid cathode elucidates the impact of structural and compositional properties of the catalyst mixtures on hydrogenation rates and selectivities.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/1/celc201901314-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/2/celc201901314.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/3/celc201901314_am.pd

How do people with diabetes describe their experiences in primary care? Evidence from 85,760 patients with self-reported diabetes from the English General Practice Patient Survey.

OBJECTIVE: Developing primary care is an important current health policy goal in the U.S. and England. Information on patients' experience can help to improve the care of people with diabetes. We describe the experiences of people with diabetes in primary care and examine how these experiences vary with increasing comorbidity. RESEARCH DESIGN AND METHODS: Using data from 906,578 responders to the 2012 General Practice Patient Survey (England), including 85,760 with self-reported diabetes, we used logistic regressions controlling for age, sex, ethnicity, and socioeconomic status to analyze patient experience using seven items covering three domains of primary care: access, continuity, and communication. RESULTS: People with diabetes were significantly more likely to report better experience on six out of seven primary care items than people without diabetes after adjusting for age, sex, ethnicity, and socioeconomic status (adjusted differences 0.88-3.20%; odds ratios [ORs] 1.07-1.18; P < 0.001). Those with diabetes and additional comorbid long-term conditions were more likely to report worse experiences, particularly for access to primary care appointments (patients with diabetes alone compared with patients without diabetes: OR 1.22 [95% CI 1.17-1.28] and patients with diabetes plus three or more conditions compared with patients without diabetes: OR 0.87 [95% CI 0.83-0.91]). CONCLUSIONS: People with diabetes in England report primary care experiences that are at least as good as those without diabetes for most domains of care. However, improvements in primary care are needed for diabetes patients with comorbid long-term conditions, including better access to appointments and improved communication.Diabetes UKThis is the author accepted manuscript. The final version is available from the American Diabetes Association via http://dx.doi.org/10.2337/dc14-109