1,358 research outputs found
Research and development program for a combined carbon dioxide removal and reduction system. Supplement 1, phase 2a - Physicochemical properties of lithium chloride lithium carbonate melt mixtures
Physiochemical properties of liquid mixtures of lithium chloride and lithium carbonat
Exact bounds on the ground-state energy of the infinite-U Hubbard model
We give upper and lower bounds for the ground-state energy of the infinite-U
Hubbard model. In two dimensions, using these bounds we are able to rule out
the possibility of phase separation between the undoped-insulating state and an
hole-rich state.Comment: 2 pages, 1 figure, to appear in Phys. Rev.
Non-destructive distinction between geogenic and anthropogenic calcite by Raman spectroscopy combined with machine learning workflow
Here, we demonstrate, for the first time, the possibility of distinguishing between geogenic and anthropogenic calcite in a non-destructive and effective way. Geogenic calcite derives from natural sedimentary and metamorphic rocks whereas anthropogenic calcite is formed artificially due to the carbonation process in mortars and plaster lime binders. Currently, their distinction is a major unaddressed issue although it is crucial across several fields such as 14C dating of historical mortars to avoid contamination with carbonate aggregates, investigating the origins of pigments, and studying the origins of sediments, to name a few. In this paper, we address this unmet need combining high-resolution micro-Raman spectroscopy with data mining and machine learning methods. This approach provides an effective means of obtaining robust and representative Raman datasets from which samples’ origins can be effectively deduced; moreover, a distinction between sedimentary and metamorphic calcite has been also highlighted. The samples, chemically identical, exhibit systematic and reliable differences in Raman band positions, band shape and intensity, which are likely related to the degree of structural order and polarization effects
Hole-depletion of ladders in SrCuO induced by correlation effects
The hole distribution in SrCuO is studied by low
temperature polarization dependent O K Near-Edge X-ray Absorption Fine
Structure measurements and state of the art electronic structure calculations
that include core-hole and correlation effects in a mean-field approach.
Contrary to all previous analysis, based on semi-empirical models, we show that
correlations and antiferromagnetic ordering favor the strong chain
hole-attraction. For the remaining small number of holes accommodated on
ladders, leg-sites are preferred to rung-sites. The small hole affinity of
rung-sites explains naturally the 1D - 2D cross-over in the phase diagram of
(La,Y,Sr,Ca)CuOComment: 6 pages, 8 figure
Effects of phase transitions in devices actuated by the electromagnetic vacuum force
We study the influence of the electromagnetic vacuum force on the behaviour
of a model device based on materials, like germanium tellurides, that undergo
fast and reversible metal-insulator transitions on passing from the crystalline
to the amorphous phase. The calculations are performed at finite temperature
and fully accounting for the behaviour of the material dielectric functions.
The results show that the transition can be exploited to extend the distance
and energy ranges under which the device can be operated without undergoing
stiction phenomena. We discuss the approximation involved in adopting the
Casimir expression in simulating nano- and micro- devices at finite
temperature
From antiferromagnetism to d-wave superconductivity in the 2D t-J model
We have found that the two dimensional t-J model, for the physical parameter
range J/t = 0.4 reproduces the main experimental qualitative features of
High-Tc copper oxide superconductors: d-wave superconducting correlations are
strongly enhanced upon small doping and clear evidence of off diagonal long
range order is found at the optimal doping \delta ~ 0.15. On the other hand
antiferromagnetic long range order, clearly present at zero hole doping, is
suppressed at small hole density with clear absence of antiferromagnetism at
\delta >~ 0.1.Comment: 4 pages, 5 figure
Effect of Coteaching on the Achievement of Middle School Students With Disabilities
From 2014 to 2015, full inclusion through coteaching practices (2 or more professionals providing instruction in the same classroom environment) was implemented at a rural southeastern middle school in Georgia to improve the low academic achievement of students with disabilities (SWDs). The problem is that 8th-grade SWDs score low on the reading and mathematics sections of the Standardized Assessment for Reading and Mathematics (STAR). The purpose of this quantitative quasi-experimental study was to examine the effect of coteaching on the achievement of 8th-grade SWDs in reading and mathematics as measured by the STAR. Vygotsky\u27s zone of proximal development was the theoretical framework for this study because cognitive development can be enhanced with adult guidance and peer collaboration. The research questions focused on the difference in STAR gain scores between the coteaching SWDs participants and the SWDs with no coteaching. The sample was 96 8th-grade SWDs. A t test was used to compare the reading and mathematics gain scores between the academic years 2012 and 2014 (without inclusion/coteaching),46 SWDs and 2015-2017 (with inclusion/coteaching), 50 SWDs. Results showed that there were significant differences in the STAR performance after coteaching implementation in reading and mathematics, p = .045 and p = .004, respectively. This study may lead to positive social change by providing data to the local educational agency leaders, administrators, teachers, and the educational community to make informed decisions about the implementation of coteaching practices, to enhance instructional practices and teaching strategies, and to improve the academic achievement of SWDs allowing them the opportunity to become college and career ready, thus enhancing their postsecondary options
Limits on Phase Separation for Two-Dimensional Strongly Correlated Electrons
From calculations of the high temperature series for the free energy of the
two-dimensional t-J model we construct series for ratios of the free energy per
hole. The ratios can be extrapolated very accurately to low temperatures and
used to investigate phase separation. Our results confirm that phase separation
occurs only for J/t greater than 1.2. Also, the phase transition into the phase
separated state has Tc of approximately 0.25J for large J/t.Comment: 4 pages, 6 figure
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