Spin-Polarized Charge Separation in a Photoexcited Transition Metal Dichalcogenide Heterobilayer at Room Temperature

Transition metal dichalcogenide (TMDC) monolayers feature spin-valley locking for band-edge electrons/holes and valley specific optical excitation by circularly polarized light. A potential application of the spin-valley polarization is to provide an efficient mechanism for spin-selective interfacial photochemistry. Here, we study spin-polarized charge separation at room temperature in a MoSe2/WSe2 heterobilayer with macroscopic dimensions. Using time-resolved Faraday rotation, we show that resonant excitation of valley-specific exciton transition in WSe2 results in spin-polarized charge separation across the MoSe2/WSe2 interface with spin polarization persisting on the 10 ps time scale. From dynamic changes in Faraday rotation and its dependences on excitation density and sample temperature, we present possible mechanisms of spin depolarization. We discuss potential applications of TMDC monolayers and heterobilayers for spin-selective interfacial photochemistry and time limits on competitive dynamics

The Ultrafast Kerr Effect in Anisotropic and Dispersive Media

The ultrafast optical Kerr effect (OKE) is widely used to investigate the structural dynamics and interactions of liquids, solutions and solids by observing their intrinsic nonlinear temporal responses through nearly-collinear four-wave mixing (FWM). Non-degenerate mixing schemes allow for background free detection and can provide information on the interplay between a material's internal degrees of freedom. Here we show a source of temporal dynamics in the OKE signal that is not reflective of the intrinsic nonlinear response but arises from group index and momentum mismatch. It is observed in two-color experiments on condensed media with sizable spectral dispersion, a common property near an optical resonance. In particular birefringence in crystalline solids is able to entirely change the character of the OKE signal via the off-diagonal tensor elements of the nonlinear susceptibility. We develop a detailed description of the phase-mismatched ultrafast OKE and show how to extract quantitative information on the spectrally resolved birefringence and group index from time-resolved experiments in one and two dimensions

Data_Sheet_1_Identification of Quantitative Trait Loci Associated With Iron Deficiency Tolerance in Maize.docx

Iron (Fe) is a limiting factor in crop growth and nutritional quality because of its low solubility. However, the current understanding of how major crops respond to Fe deficiency and the genetic basis remains limited. In the present study, Fe-efficient inbred line Ye478 and Fe-inefficient inbred line Wu312 and their recombinant inbred line (RIL) population were utilized to reveal the physiological and genetic responses of maize to low Fe stress. Compared with the Fe-sufficient conditions (+Fe: 200 μM), Fe-deficient supply (−Fe: 30 μM) significantly reduced shoot and root dry weights, leaf SPAD of Fe-efficient inbred line Ye478 by 31.4, 31.8, and 46.0%, respectively; decreased Fe-inefficient inbred line Wu312 by 72.0, 45.1, and 84.1%, respectively. Under Fe deficiency, compared with the supply of calcium nitrate (N1), supplying ammonium nitrate (N2) significantly increased the shoot and root dry weights of Wu312 by 37.5 and 51.6%, respectively; and enhanced Ye478 by 23.9 and 45.1%, respectively. Compared with N1, N2 resulted in a 70.0% decrease of the root Fe concentration for Wu312 in the −Fe treatment, N2 treatment reduced the root Fe concentration of Ye478 by 55.8% in the −Fe treatment. These findings indicated that, compared with only supplying nitrate nitrogen, combined supply of ammonium nitrogen and nitrate nitrogen not only contributed to better growth in maize but also significantly reduced Fe concentration in roots. In linkage analysis, ten quantitative trait loci (QTLs) associated with Fe deficiency tolerance were detected, explaining 6.2–12.0% of phenotypic variation. Candidate genes considered to be associated with the mechanisms underlying Fe deficiency tolerance were identified within a single locus or QTL co-localization, including ZmYS3, ZmPYE, ZmEIL3, ZmMYB153, ZmILR3 and ZmNAS4, which may form a sophisticated network to regulate the uptake, transport and redistribution of Fe. Furthermore, ZmYS3 was highly induced by Fe deficiency in the roots; ZmPYE and ZmEIL3, which may be involved in Fe homeostasis in strategy I plants, were significantly upregulated in the shoots and roots under low Fe stress; ZmMYB153 was Fe-deficiency inducible in the shoots. Our findings will provide a comprehensive insight into the physiological and genetic basis of Fe deficiency tolerance.</p

Data_Sheet_2_Identification of Quantitative Trait Loci Associated With Iron Deficiency Tolerance in Maize.xlsx

Iron (Fe) is a limiting factor in crop growth and nutritional quality because of its low solubility. However, the current understanding of how major crops respond to Fe deficiency and the genetic basis remains limited. In the present study, Fe-efficient inbred line Ye478 and Fe-inefficient inbred line Wu312 and their recombinant inbred line (RIL) population were utilized to reveal the physiological and genetic responses of maize to low Fe stress. Compared with the Fe-sufficient conditions (+Fe: 200 μM), Fe-deficient supply (−Fe: 30 μM) significantly reduced shoot and root dry weights, leaf SPAD of Fe-efficient inbred line Ye478 by 31.4, 31.8, and 46.0%, respectively; decreased Fe-inefficient inbred line Wu312 by 72.0, 45.1, and 84.1%, respectively. Under Fe deficiency, compared with the supply of calcium nitrate (N1), supplying ammonium nitrate (N2) significantly increased the shoot and root dry weights of Wu312 by 37.5 and 51.6%, respectively; and enhanced Ye478 by 23.9 and 45.1%, respectively. Compared with N1, N2 resulted in a 70.0% decrease of the root Fe concentration for Wu312 in the −Fe treatment, N2 treatment reduced the root Fe concentration of Ye478 by 55.8% in the −Fe treatment. These findings indicated that, compared with only supplying nitrate nitrogen, combined supply of ammonium nitrogen and nitrate nitrogen not only contributed to better growth in maize but also significantly reduced Fe concentration in roots. In linkage analysis, ten quantitative trait loci (QTLs) associated with Fe deficiency tolerance were detected, explaining 6.2–12.0% of phenotypic variation. Candidate genes considered to be associated with the mechanisms underlying Fe deficiency tolerance were identified within a single locus or QTL co-localization, including ZmYS3, ZmPYE, ZmEIL3, ZmMYB153, ZmILR3 and ZmNAS4, which may form a sophisticated network to regulate the uptake, transport and redistribution of Fe. Furthermore, ZmYS3 was highly induced by Fe deficiency in the roots; ZmPYE and ZmEIL3, which may be involved in Fe homeostasis in strategy I plants, were significantly upregulated in the shoots and roots under low Fe stress; ZmMYB153 was Fe-deficiency inducible in the shoots. Our findings will provide a comprehensive insight into the physiological and genetic basis of Fe deficiency tolerance.</p

Tuning Temperature Dependence of Dopant Luminescence via Local Lattice Strain in Core/Shell Nanocrystal Structure

We report the tunable temperature dependence of Mn luminescence spectral characteristics (peak position and bandwidth) in Mn-doped CdS/ZnS core/shell nanocrystals via controlled local lattice strain at the dopant site that affects the local vibronic coupling and local thermal expansion. The lattice mismatch at the core/shell interface creates a gradient of lattice strain in the shell along the radial direction that allows varying the local lattice strain at the Mn²⁺ site via the controlled radial doping location. Increasing the local lattice strain at the Mn²⁺ site results in the stronger temperature broadening of Mn luminescence bandwidth due to the increasing softening of the vibrational mode coupled to Mn²⁺ ligand field transition. Larger local lattice strain also causes a stronger temperature dependence of the luminescence peak, which indicates the enhanced local thermal expansion at the dopant site

Selected candidate reference genes, primers, and amplicon characteristics.

<p>Selected candidate reference genes, primers, and amplicon characteristics.</p

Correlation between papaya fruit pulp firmness and expression levels of ethylene-related genes.

<p>*, significant at <i>P</i>≦<i>0.05</i>;</p><p>**, significant at <i>P</i>≦<i>0.01</i>.</p><p>Correlations were based on n = 18 (three replicates × six sampling time points (after exogenous ethylene treatment)).</p><p>12°C, stored at 12°C; 7°C, stored at 7°C; 25°C, without low temperature storage and directly treated with exogenous ethylene for ripening at 25°C.</p><p>Correlation between papaya fruit pulp firmness and expression levels of ethylene-related genes.</p

A Hot Electron–Hole Pair Breaks the Symmetry of a Semiconductor Quantum Dot

The best-understood property of semiconductor quantum dots (QDs) is the size-dependent optical transition energies due to the quantization of charge carriers near the band edges. In contrast, much less is known about the nature of hot electron–hole pairs resulting from optical excitation significantly above the bandgap. Here, we show a transient Stark effect imposed by a hot electron–hole pair on optical transitions in PbSe QDs. The hot electron–hole pair does not behave as an exciton, but more bulk-like as independent carriers, resulting in a transient and varying dipole moment which breaks the symmetry of the QD. As a result, we observe redistribution of optical transition strength to dipole forbidden transitions and the broadening of dipole-allowed transitions during the picosecond lifetime of the hot carriers. The magnitude of symmetry breaking scales with the amount of excess energy of the hot carriers, diminishes as the hot carriers cool down and disappears as the hot electron–hole pair becomes an exciton. Such a transient Stark effect should be of general significance to the understanding of QD photophysics above the bandgap

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Expression levels of <i>CpERS</i>, <i>CpETR1</i>, <i>CpEIN2</i> and <i>CpEIL1</i> in papaya fruit during low temperature-storage and ripening at 25°C after treatment with exogenous ethylene.

<p>Sampling details were the same as those labeled <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116002#pone-0116002-g001" target="_blank">Fig 1</a>. The details for quantitative real-time PCR details are as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116002#pone-0116002-g002" target="_blank">Fig 2</a>.</p