Poplars have a strong response to light, and shade is one of the main environmental factors that limits the growth and development of poplars. Exploring the response mechanism of the developing xylem of poplar under shady conditions is of great reference significance for improving wood yields. In this study, three excellent hybrids of poplar (Populus euramericana ‘Zhonglin46’ (Pe), Populus deltoides ‘27-17’ (Pd), Populus × ‘Wq156’ (Pw) were studied under shady conditions. Based on the phenotypic data and developing a xylem transcriptome analysis, the molecular mechanism of poplars’ response to shade was preliminarily revealed, and the core regulatory genes responding to shade were identified by a weighted co-expression network analysis (WGCNA). The results showed that Pw growth was significantly affected by shade, while Pe growth was slightly affected by shade. An enrichment analysis of 13,675 differentially expressed genes (DEGs) found that shade affected the expression of genes related to the glutathione metabolic pathway. The WGCNA analysis identified two modules (“Brown” and “Purple”) related to the shade response and discovered seven hub genes. These hub genes were related to xylem development, vascular cambium division, stomatal development, and phytochrome A signal transduction. These results provide important basic information for gaining insight into the molecular response to shade in different poplar hybrids.
Organic semiconductor thin films can undergo severe molecular packing changes by simple post-processing modification. Bistetracene, a high-performance organic semiconductor employed in thin film transistors exhibits a great example of this phenomena. This cover describes how solvent vapor annealing converts the film from 1D π-stacking motif to the bulk-crystal 2D “brick-layer” packing to yield high mobility organic transistor arrays. This is reported by Alejandro L. Briseno and co-workers in article number 1701607.
In order to reduce dependence on petroleum resources, three different biobased epoxy monomers (Eu-EP-1, Eu-EP-2, and Eu-EP-3) with a biobased carbon content of 76.9%–83.3% were prepared from eugenol, which can be derived from lignin. Three eugenol-based epoxy thermosets (Eu-EP-1/IPDA, Eu-EP-2/IPDA, and Eu-EP-3/IPDA) were then obtained by curing Eu-EP monomer with a commercial IPDA (isophorone diamine) hardener; the curing activation energy was in the range of 37.4–48.2 kJ/mol, the gel content ranged from 95.4%–96.5%, and the cross-linking degree reached 1185–2119 mol/m3, confirming that Eu-EP and IPDA were cured to form cross-linking network structures. Therefore, the Eu-EP/IPDA thermosets had excellent in-service performance with a Tg of 63.9–76.3 °C and a tensile strength of 34.7–43.1 MPa. However, the Eu-EP/IPDA thermosets with permanent chemical bonds were difficult to recycle. Since Eu-EP-2/IPDA had balanced performance, Eu-EP-2 was selected to develop recyclable Eu-EP/AFD epoxy vitrimers by curing with AFD (4,4′-dithiodiphenylamine). The resulting Eu-EP-2/AFD1.00 epoxy vitrimer had a Tg of 79.4 °C and a tensile strength of 39.2 MPa, and the remodeling of the Eu-EP-2/AFD1.00 epoxy vitrimer could be achieved by hot pressing at 200 °C for 6 h; the self-healing of the scratched material could be achieved by heating at 180 °C for 2 h, and the Eu-EP-2/AFD1.00 epoxy vitrimer could be dissolved in mercaptoethanol. Therefore, Eu-EP is a potential sustainable epoxy monomer for the development of epoxy materials with a balanced in-service performance and recyclability. This study offers a facile solution for the development of sustainable eugenol-based epoxy materials.
Abstract Background Poplar trees provide a large amount of wood material, but many parts of the world are arid or semi-arid areas because of insufficient annual precipitation, which seriously affects the growth of poplar trees. Populus simonii ‘Tongliao1’ shows strong tolerance to stress environments, and Populus deltoides ‘Danhong’ shows a stronger growth rate in a suitable environment. To identify drought tolerance-related QTLs and genes, an F 1 population derived from the cross between the ‘Danhong’ and ‘Tongliao 1’ Populus was assessed under drought stress. Results We measured drought-related traits such as the relative height growth, relative diameter growth, leaf senescence number, specific leaf area, and leaf relative water content in the population under control and drought environments. The results showed that drought stress reduced the plant height relative growth, ground diameter relative growth, specific leaf area and leaf relative water content and increased the number of leaf drops. A total of 208 QTLs were identified by QTL mapping analysis, and they consisted of 92, 63 and 53 QTLs under control, drought stress treatment and drought index conditions, respectively. A molecular identification marker for drought tolerance, np2841, which was associated with a QTL (qDLRWC-LG10-1) for relative leaf water content, was initially developed. We mined 187 candidate genes for QTL regions of five traits under a drought environment. The reference genome annotation for Populus trichocarpa and a homologous gene analysis of Arabidopsis thaliana identified two candidate genes, Potri.003G171300 and Potri.012G123900 , with significant functions in response to drought stress. We identified five key regulatory genes ( Potri.006G273500 , Potri.007G111500 , Potri.007G111600 , Potri.007G111700 , and Potri.007G111800 ) related to drought tolerance through the poplar coexpression network. Conclusion In this study, our results indicate that the QTLs can effectively enhance the drought tolerance of poplar. It is a step closer towards unravelling the genetic basis of poplar drought tolerance-related traits, and to providing validated candidate genes and molecular markers for future genetic improvement.
Dynamics of reverse saturable absorption (RSA) and optical limiting (OL) in C60 medium are studied in detail employing rate equation theory. Experimental results of RSA and OL in C60toluene solution with a Q-switched frequency-double YAG laser agree well with the theoretical simulations. The contribution of each energy level of C60 molecule to RSA and the influence of different laser wavelength and pulse duration on RSA and OL are also dicussed.
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