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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.

Polymorph- and coformer-dependent photoluminescence (PL) are among the variety of novel solid-state PL phenomena recently observed in many molecular crystals. They are of particular research interest due to their direct connections to two heavily investigated topics in crystal engineering: polymorphism and cocrystallization. Herein, we apply a novel computational methodology, initially proposed and successfully applied in our previous investigation of piezochromism, to theoretical modeling of the polymorph- and coformer-dependent PL in the well-known ROY polymorphs and the recently synthesized 9-acetylanthracene (9-ACA) cocrystals, respectively. Our methodology offers satisfactory prediction of the experimentally observed color zoning for the ROY polymorphs and provides good qualitative and quantitative accuracy for the emission (fluorescence) energies of the 9-ACA cocrystals, although the results in both cases may be adversely affected by delocalization error in the density-functional methods employed. While the polymorph-dependent PL in ROY is found to be controlled by the intramolecular geometry, modeling of the periodic crystal environment is necessary for accurate prediction of the coformer-dependent PL in the 9-ACA cocrystals, which is driven by charge transfer.

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.

Summary form only given. Two-electrode Graphite Spark Gap Switch (TGSGS) is used as the main discharge switch in Pulsed Power Conditioning System (PPCS). Normally the TGSGS is controlled by the application of an external trigger impulse. The trigger impulse with peak value of more than 120 kV and rise time of less than 30 ns is provided by a trigger generator based on pulse transformer1. In this paper, the operating situation of the TGSGS and the injection of the trigger generator are investigated and described. When the main capacitor is charged on different DC voltages, the breakdown voltages of the TGSGS under the trigger impulse are measured. The calculation and the experimental results of the breakdown voltage under ns impulse are presented and compared. The results indicate that the over-voltage breakdown of the TGSGS in PPCS is sensitive to the peak value, and rise time of the trigger impulse, and does not require too much energy. At last the time delay and jitter of the TGSGS in PPCS is presented.

Starting from the updated requirements of an advanced laser system, a switch-trigger system for a 2.0 MJ pulsed power supply module has been developed. This paper discusses the design, construction and testing of this switch-trigger system. The two-electrode construction for the spark gap switch was selected due to the superiority in long working life, high peak currents and fast rise-time of currents. The trigger generator based on resonant charging of pulse transformer was constructed. A magnetic isolator and a pressure controller were the auxiliary equipments of this system. In the section about the mathematical principles, the equations of the lifetime and stability of this spark gap switch with graphite electrodes are given. These expressions can be regarded as the design basis of the same type switch. As for the trigger generator, the analysis states that an appropriate ratio can be obtained when using the resonant charging based on core-type pulse transformer. The charging time is dependent on the leakage inductance and the capacitance of the primary and secondary capacitors. Extensive testing has proved the operating parameters of the switches and trigger generator. The measured discharge current waveform of 2.0 MJ capacitive pulsed power supply module is demonstrated to be over 500 kA peak-current and 500 µs pulse-width. And the life test has proved that the switch-trigger system can support more than 200 kC transfer charge. Via replacing the electrodes, the lifetime of this switch can be extended more.

A simple, single-channel millimeter-wave interferometer system has been designed, fabricated, and installed on the J-TEXT tokamak. For the plasma density anticipated on J-TEXT, a solid-state source operating at 150 GHz has been chosen to minimize errors due to both vibration along the beam path and refraction in the plasma. The new aspect of the interferometer design is to use a subharmonic mixer for detection with a frequency doubled 150 GHz source. It employs a single source which is bias-tuned and modulated with a sawtooth wave form up to 100 kHz in order to generate the intermediate frequency. The 12.5 GHz voltage-controlled oscillator is multiplied to 75 GHz before a final doubler raises it to 150 GHz. A portion of the 75 GHZ power is used for the local oscillator (LO) and is directly connected to the LO input of the subharmonic mixer. The phase is evaluated by a digital phase comparator using a software-based algorithm. Detection noise limits the minimum resolvable phase change with the interferometer to ±0.05 fringe, which corresponds to an averaged electron density change along the chord of ±1.1 × 10(17) m(-2). The maximum measurable electron density is expected to be ∼9 × 10(19) m(-3). A comparison of preliminary results from the millimeter wave interferometer with that from the far-infrared hydrogen cyanide laser (wavelength of 337 μm) interferometer shows good agreement during the pulse flat-top period. The millimeter wave interferometer system will be used as a part of the density feedback control system in the future.

For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.