Charge order textures induced by non-linear lattice coupling in a half-doped manganite

The self-organization of strongly interacting electrons into superlattice structures underlies the properties of many quantum materials. How these electrons arrange within the superlattice dictates what symmetries are broken and what ground states are stabilized. Here we show that cryogenic scanning transmission electron microscopy enables direct mapping of local symmetries and order at the intra-unit-cell level in the model charge-ordered system Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. In addition to imaging the prototypical site-centered charge order, we discover the nanoscale coexistence of an exotic intermediate state which mixes site and bond order and breaks inversion symmetry. We further show that nonlinear coupling of distinct lattice modes controls the selection between competing ground states. The results demonstrate the importance of lattice coupling for understanding and manipulating the character of electronic self-organization and highlight a novel method for probing local order in a broad range of strongly correlated systems

Characterization of Sulfur and Nanostructured Sulfur Battery Cathodes in Electron Microscopy Without Sublimation Artifacts

Lithium sulfur (Li-S) batteries have the potential to provide higher energy storage density at lower cost than conventional lithium ion batteries. A key challenge for Li-S batteries is the loss of sulfur to the electrolyte during cycling. This loss can be mitigated by sequestering the sulfur in nanostructured carbon-sulfur composites. The nanoscale characterization of the sulfur distribution within these complex nanostructured electrodes is normally performed by electron microscopy, but sulfur sublimates and redistributes in the high vacuum conditions of conventional electron microscopes. The resulting sublimation artifacts render characterization of sulfur in conventional electron microscopes problematic and unreliable. Here, we demonstrate two techniques, cryogenic transmission electron microscopy (cryo-TEM) and scanning electron microscopy in air (airSEM), that enable the reliable characterization of sulfur across multiple length scales by suppressing sulfur sublimation. We use cryo-TEM and airSEM to examine carbon-sulfur composites synthesized for use as Li-S battery cathodes, noting several cases where the commonly-employed sulfur melt infusion method is highly inefficient at infiltrating sulfur into porous carbon hosts

Study Skills in High School

The purpose of the researcher was to investigate the impact of a study skills class on student\u27s achievement test scores. The independent variables were participation in the study skills class, gender and socioeconomic status. The dependent variables were California Test of Basic Skills scores (Reading, Language, Mathematics, Study Skills, Social Studies and Total Battery). The students in the present study were freshmen. The experimental group was made up of 17 students enrolled in the study skills class. The control group consisted of 19 freshmen who had not enrolled in the study skills class. Three composite null hypotheses were tested at the .05 level. A pretest/posttest single-factor analysis of covariance was employed. A total of 18 comparisons were made. Two of the 18 comparisons were statistically significant at the .05 level. The statistically significant comparisons were for the following: 1. the independent variable participation type and the dependent variable Reading, and 2. the independent variable participation type and the dependent variable composite score. The results of the present study indicated the following: 1. the control group had a statistically larger adjusted posttest mean Reading score that the participating group, and 2. the control group had a statistically larger adjusted posttest mean composite score than the participating group. The results of the present study appeared to support the following generalizations; 1. a study skills class of the type examined in this study is not effective in improving standardized achievement test results, 2. the gender of students participating in the Study Skills class is not associated with content achievement, and 3. the socioeconomic status of students participating in the Study Skills class is not associated with content achievement

Data from: Organo-organic and organo-mineral interfaces in soil at the nanometer scale

Please cite as: Angela R. Possinger, Michael J. Zachman, Akio Enders, Barnaby D. A. Levin, David A. Muller, Lena F. Kourkoutis and Johannes Lehmann. (2020) Data from: Organo-organic and organo-mineral interfaces in soil at the nanometer scale. [Dataset] Cornell University eCommons Repository. https://doi.org/10.7298/6vtr-c668The capacity for soils to serve as a carbon (C) reservoir is dependent on the persistence of soil organic carbon (SOC). Interactions between organic and mineral phases in soil are a key component of long-term SOC persistence, but the small spatial scale at which they occur makes direct observation of interaction mechanisms challenging. In this work, we used cryogenic scanning transmission electron microscopy with electron energy loss spectroscopy (cryo-STEM-EELS) to image and chemically characterize organo-mineral and organo-organic interfaces in a natural soil sample. This dataset includes cryo-STEM-EELS point, line, and 2D map measurements, as well as additional characterization data from electron dispersive X-ray (EDX) spectroscopy. Statistical analysis of cryo-STEM-EELS data and figure source data are also included. This study revealed a patchy distribution of organic forms, rather than previously observed organized layers at mineral surfaces. We detected enrichment of nitrogen (N) at both organo-mineral and organo-organic interfaces, but different forms of C, with oxidized C or alkyl C enriched at organo-mineral or organo-organic interfaces, respectively. This study supports a new view of SOC spatial architecture at mineral surfaces, and provides motivation to evaluate how organic N composition of organic inputs may affect long-term SOC persistence