The new compounds Li2Mg2Si2S6and Li2Mg2Ge2S6have been prepared via traditional high‐temperature, solid‐state synthesis. The title compounds crystallize in the polar, noncentrosymmetric, trigonal space group
The manuscript titled “Modeling nonisothermal crystallization in a BaO∙2SiO2glass” contains two minor mistakes. This errata acknowledges and corrects the errors. The corrections clarify the details of the simulations performed in the original work and do not impact the results.
more » « less- NSF-PAR ID:
- 10453297
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of the American Ceramic Society
- Volume:
- 104
- Issue:
- 1
- ISSN:
- 0002-7820
- Page Range / eLocation ID:
- p. 654-654
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract P 31m (No. 157) and adopt a new structure type featuring staggered, ethane‐like (T2S6)6−units, where T=Si or Ge. These (T2S6)6−units are nestled within the holes of magnesium‐sulfide “layers” that are created through the edge‐sharing of MgS6octahedra. The holes found in the lithium‐sulfide “layers”, created by LiS6edge‐sharing octahedra, remain vacant, containing no (T2S6)6−anionic group. Through the face sharing of the respective MgS6and LiS6octahedra, the magnesium‐sulfide and lithium‐sulfide “layers” are stitched together resulting in an overall three‐dimensional structure. The optical bandgaps of Li2Mg2Si2S6and Li2Mg2Ge2S6are 3.24 and 3.18 eV, respectively, as estimated from optical diffuse reflectance UV‐Vis‐NIR spectroscopy. The compounds exhibit second harmonic generation responses of ∼0.24×KDP and ∼2.92×α‐quartz for Li2Mg2Si2S6and ∼0.17×KDP and ∼2.08×α‐quartz for Li2Mg2Ge2S6, using a Nd:YAG laser at 1.064 μm. Electronic structure calculations were performed using density functional theory and the linearized augmented plane‐wave approach within the WIEN2k software package. Examination of the electronic band structures shows that these compounds are indirect bandgap semiconductors. -
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Abstract Questions Plant–plant interactions are key processes that strongly affect the survival, growth and reproduction of individuals in plant communities. In grasslands, the micro‐environment generated under the canopy of shrubs could differentially affect co‐occurring species with different abiotic requirements. In a C3/C4grassland with scattered shrubs, we asked the following questions: (a) Does the aerial effect, the below‐ground effect, and the net effect of shrubs affect the vegetative and reproductive biomass, the number of tillers, the biomass allocation, and the leaf elongation rate of grasses? and (b) Do these effects differ between C3and C4grasses?
Location Temperate sub‐humid grassland of Uruguay.
Methods We planted one C3and two C4grasses under a shrub canopy and in adjacent open sites. Half of the grasses were planted with a fabric bag to reduce root competition with the shrub. We measured leaf elongation rate, the number of tillers produced and the biomass of the grasses in every treatment. We also measured photosynthetic photon flux density (
PPFD ), air temperature and wind speed under shrub canopies and in adjacent open sites.Results Root biomass, aerial biomass and reproductive biomass, the number of tillers and the leaf elongation rate of the C4grasses were negatively affected by the reduction in radiation and probably by below‐ground competition with the shrub. On the other hand, the leaf elongation rate of the C3grasses was positively affected by the shrub canopy.
PPFD , air temperature and wind speed were lower under shrubs than in adjacent open sites.Conclusions Our results show the interplay between plant interactions and photosynthetic metabolism on the vegetative and reproductive performance of grasses. The micro‐environmental conditions generated below shrub canopies create a more appropriate site for the growth of C3than for C4grasses. These results show that shrubs may differentially affect co‐occurring species with different abiotic requirements.
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Background Cardiac MR fingerprinting (cMRF) is a novel technique for simultaneous T1and T2mapping.
Purpose To compare T1/T2measurements, repeatability, and map quality between cMRF and standard mapping techniques in healthy subjects.
Study Type Prospective.
Population In all, 58 subjects (ages 18–60).
Field Strength/Sequence cMRF, modified Look–Locker inversion recovery (MOLLI), and T2‐prepared balanced steady‐state free precession (bSSFP) at 1.5T.
Assessment T1/T2values were measured in 16 myocardial segments at apical, medial, and basal slice positions. Test–retest and intrareader repeatability were assessed for the medial slice. cMRF and conventional mapping sequences were compared using ordinal and two alternative forced choice (2AFC) ratings.
Statistical Tests Paired
t ‐tests, Bland–Altman analyses, intraclass correlation coefficient (ICC), linear regression, one‐way analysis of variance (ANOVA), and binomial tests.Results Average T1measurements were: basal 1007.4
± 96.5 msec (cMRF), 990.0± 45.3 msec (MOLLI); medial 995.0± 101.7 msec (cMRF), 995.6± 59.7 msec (MOLLI); apical 1006.6± 111.2 msec (cMRF); and 981.6± 87.6 msec (MOLLI). Average T2measurements were: basal 40.9± 7.0 msec (cMRF), 46.1± 3.5 msec (bSSFP); medial 41.0± 6.4 msec (cMRF), 47.4± 4.1 msec (bSSFP); apical 43.5± 6.7 msec (cMRF), 48.0± 4.0 msec (bSSFP). A statistically significant bias (cMRF T1larger than MOLLI T1) was observed in basal (17.4 msec) and apical (25.0 msec) slices. For T2, a statistically significant bias (cMRF lower than bSSFP) was observed for basal (–5.2 msec), medial (–6.3 msec), and apical (–4.5 msec) slices. Precision was lower for cMRF—the average of the standard deviation measured within each slice was 102 msec for cMRF vs. 61 msec for MOLLI T1, and 6.4 msec for cMRF vs. 4.0 msec for bSSFP T2. cMRF and conventional techniques had similar test–retest repeatability as quantified by ICC (0.87 cMRF vs. 0.84 MOLLI for T1; 0.85 cMRF vs. 0.85 bSSFP for T2). In the ordinal image quality comparison, cMRF maps scored higher than conventional sequences for both T1(all five features) and T2(four features).Data Conclusion This work reports on myocardial T1/T2measurements in healthy subjects using cMRF and standard mapping sequences. cMRF had slightly lower precision, similar test–retest and intrareader repeatability, and higher scores for map quality.
Evidence Level 2
Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2020;52:1044–1052.
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Abstract The Raman spectral behavior of N2, CO2, and CH4in ternary N2–CO2–CH4mixtures was studied from 22°C to 200°C and 10 to 500 bars. The peak position of N2in all mixtures is located at lower wavenumbers compared with pure N2at the same pressure (
P )–temperature (T ) (PT ) conditions. The Fermi diad splitting in CO2is greater in the pure system than in the mixtures, and the Fermi diad splitting increases in the mixtures as CO2concentration increases at constantP andT . The peak position of CH4in the mixtures is shifted to higher wavenumbers compared with pure CH4at the samePT conditions. However, the relationship between peak position and CH4mole fraction is more complicated compared with the trends observed with N2and CO2. The relative order of the peak position isotherms of CH4and N2in the mixtures in pressure–peak position space mimics trends in the molar volume of the mixtures in pressure–molar volume space. Relationships between the direction of peak shift of individual components in the mixtures, the relative molar volumes of the mixtures, and the attraction and repulsion forces between molecules are developed. Additionally, the relationship between the peak position of N2in ternary N2–CO2–CH4mixtures with pressure is extended to other N2‐bearing systems to assess similarities in the Raman spectral behavior of N2in various systems. -
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Abstract A unique approach is used to relate the HOMO‐LUMO energy difference to the difference between the ionization potential (IP) and electron affinity (EA) to assist in deducing not only the colors, but also chromophores in elemental nonmetals. Our analysis focuses on compounds with lone pair electrons and σ electrons, namely X2(X = F, Cl, Br, I), S8and P4. For the dihalogens, the [IP – EA] energies are found to be: F2(12.58 eV), Cl2(8.98 eV), Br2(7.90 eV), I2(6.78 eV). We suggest that the
intera halogen X–X bond itself is the chromophore for these dihalogens, in which the light absorbed by the F2, Cl2, Br2, I2leads to longer wavelengths in the visible by a π → σ* transition. Trace impurities are a likely case of cyclic S8which contains amounts of selenium leading to a yellow color, where the [IP – EA] energy of S8is found to be 7.02 eV. Elemental P4with an [IP – EA] energy of 9.09 eV contains a tetrahedral and σ aromatic structure. In future work, refinement of the analysis will be required for compounds with π electrons and σ electrons, such as polycyclic aromatic hydrocarbons (PAHs).
