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Accurate germplasm characterization is a vital step for accelerating crop genetic improvement, which remains largely infeasible for crops such as bread wheat (Triticum aestivum L.), which has a complex genome that undergoes frequent introgression and contains many structural variations. Here, we propose a genomic strategy called ggComp, which integrates resequencing data with copy number variations and stratified single-nucleotide polymorphism densities to enable unsupervised identification of pairwise germplasm resource-based Identity-By-Descent (gIBD) blocks. The reliability of ggComp was verified in wheat cultivar Nongda5181 by dissecting parental-descent patterns represented by inherited genomic blocks. With gIBD blocks identified among 212 wheat accessions, we constructed a multi-scale genomic-based germplasm network. At the whole-genome level, the network helps to clarify pedigree relationship, demonstrate genetic flow, and identify key founder lines. At the chromosome level, we were able to trace the utilization of 1RS introgression in modern wheat breeding by hitchhiked segments. At the single block scale, the dissected germplasm-based haplotypes nicely matched with previously identified alleles of “Green Revolution” genes and can guide allele mining and dissect the trajectory of beneficial alleles in wheat breeding. Our work presents a model-based framework for precisely evaluating germplasm resources with genomic data. A database, WheatCompDB (http://wheat.cau.edu.cn/WheatCompDB/), is available for researchers to exploit the identified gIBDs with a multi-scale network.

This study identified the SQUAMOSA Promoter Binding Proteins transcription factor SBP from the whole genome of Quinoa by analyzing the phylogenetic relationship, gene structure, chromosome location and gene replication, upstream cis-regulatory element, tissue expression, and construction of the SBP protein interaction network, as well as analyzing the characteristics of the SBP tissue expression pattern under salt stress. It serves as the foundation for the study and application of Quinoa SBP. The results showed that 23 genes of the CqSBP family were identified by bioinformatics analysis, and their amino acid physical and chemical properties showed diversity. The family proteins were hydrophilic, and the subcellular localization showed that 23 CqSBPs were located in the nucleus. The SBP family genes are unevenly distributed on the 12 chromosomes of Quinoa; the upstream cis-acting element analysis shows that there are 49 elements with plant hormones, stress, light response, and tissue-specific expression, and all CqSBPs contain one or more TATA box elements. Protein interaction network analysis shows that all CqSBP proteins appear in the known interaction network of Arabidopsis; the expression of different SBP genes in different organs and periods of Quinoa is different, and the expression of SBP genes has certain tissue specificity. The expression of CqSBP showed many changes under salt stress.

Studying the distribution pattern and driving mechanism of Soil Nitrogen (SN) in the agricultural areas of the Qinghai-Tibet Plateau is of certain significance for the rational use of N fertilizer, improving the quality of land use and protecting the environment. The SN content of cultivated soil in Qinghai-Tibet Plateau agricultural areas was analyzed by combining geographical and meteorological factors. It was found that the average Soil Total N (STN) in farmland was 2.4690 g/kg, which was the first class standard (>2.0 g/kg) of nutrient classification standard in the second national soil census. Horizontally, the areas with low N are mainly concentrated in the southwest of the Qinghai-Tibet Plateau and the high in the southeast and eastern regions of the Tibetan Plateau. From the vertical distribution pattern of 2000 m to 5000 m, it gradually decreases with the increase of altitude. The climatic factors affecting the STN are daily average temperature ≥ 10°C accumulated temperature > annual evaporation > daily average temperature ≥ 0°C accumulated temperature. The climatic factors that affect the Soil Available N (SAN) are daily average temperature ≥ 10°C accumulated temperature > daily average temperature ≥ 0°C accumulated temperature > annual evaporation> annual sunshine hours> monthly average maximum temperature > annual precipitation amount.

Atomic and molecular dispersion coefficients can now be calculated routinely using density-functional theory. In this work, we present the first determination of how electronic excitation affects molecular C6 London dispersion coefficients from the exchange-hole dipole moment (XDM) dispersion model. Excited states are typically found to have larger dispersion coefficients than the corresponding ground states, due to their more diffuse electron densities. A particular focus is both intramolecular and intermolecular charge-transfer excitations, which have high absorbance intensities and are important in organic dyes, light-emitting diodes, and photovoltaics. In these classes of molecules, the increase in C6 for the electron-accepting moiety is largely offset by a decrease in C6 for the electron-donating moiety. As a result, the change in dispersion energy for a chromophore interacting with neighbouring molecules in the condensed phase is minimal.

In order to study the space distribution of Grain Number per spike (GNS) and its relationship with the environmental factors in the Qinghai-Tibet Plateau, 83 data samples from different ecological areas were selected for GNS inverstigation. Meanwhile, the seeds of highland barley were harvested and planted in the farm of Xizang Agriculture and Animal Husbandry College; the varieties without genetic differences were selected and their GNS was analyzed with the local geography and climate factors. The results shows that: (1) In the horizontal direction, GNS forms the high value area of Central and South Tibetan taking Qiongjie and Longzi as the center; (2) In the vertical direction, GNS appears with double high value areas at the altitude of 3900m-4200m and above 4500m respectively and the corresponding GNS is 52.9±17.6 and 57.2±0.2 respectively; (3) the environmental factors influencing GNS are in the order that soil total nitrogen>soil available nitrogen>the average precipitation at heading-filling stage>altitude>soil organic matter>soil total phosphorus>the average rainfall at jointing-heading stage>soil available potassium>the average rainfall at tillering-jointing stage.

First singlet (S1) excitations are of primary importance in the photoluminescence spectra of organic chromophores. However, due to the multi-determinantal nature of the singlet excited states, standard Kohn-Sham density-functional theory (DFT) is not applicable. While linear-response time-dependent DFT is the method of choice for the computation of excitation energies, it fails severely for excitations with charge-transfer character. Becke’s recent virial exciton model [A. D. Becke, J. Chem. Phys. 148, 044112 (2018)] offers a promising solution to employ standard DFT for calculation of the S1 excitation energy in molecular systems. Here, it is shown that the virial exciton model is free of charge-transfer error. It is equally reliable for S1 excitations with significant charge-transfer character as for other classes of transitions.First singlet (S1) excitations are of primary importance in the photoluminescence spectra of organic chromophores. However, due to the multi-determinantal nature of the singlet excited states, standard Kohn-Sham density-functional theory (DFT) is not applicable. While linear-response time-dependent DFT is the method of choice for the computation of excitation energies, it fails severely for excitations with charge-transfer character. Becke’s recent virial exciton model [A. D. Becke, J. Chem. Phys. 148, 044112 (2018)] offers a promising solution to employ standard DFT for calculation of the S1 excitation energy in molecular systems. Here, it is shown that the virial exciton model is free of charge-transfer error. It is equally reliable for S1 excitations with significant charge-transfer character as for other classes of transitions.

Normally, a three-electrode spark-gap switch is controlled by the application of an external trigger impulse. In this paper, a novel self-breakdown sharpening switch based on the three-electrode spark-gap switch is proposed. However, in this paper, the trigger electrode is connected to ground through a resistor, with the prespark between the trigger and the main electrodes providing the electrons and ions that initiate conduction of the main gap. A prototype sharpening switch with a breakdown voltage of 116.0 kV ± 1.0 kV and a breakdown time of 3.396 μs ± 0.036 μs is described. When compared with a conventional two-electrode spark-gap sharpening switch, the novel sharpening switch has both a more stable breakdown voltage and lower jitter, and the dc breakdown and impulse breakdown characteristics of the two types of switches are presented and compared. When the impedance of the resistor connected to the trigger electrode is high, it is demonstrated that both the value of this resistor and also the type of load have little effect on the characteristics of the novel switch. However, the breakdown voltage of the novel sharpening switch was found to be sensitive to the rise time of the input pulse from the trigger generator. The prototype sharpening switch has a lifetime at least 20 000 shots and is now in use in a major pulsed power conditioning system.