目的水稻产量由单位面积有效穗数、每穗粒数和粒重3个因素构成,其中,粒重主要由水稻的籽粒形态决定.筛选和鉴定新的粒型突变材料和基因,可为产量性状的分子设计育种奠定基础.方法在籼稻保持系西大1B(XD1B)的甲基磺酸乙酯(EMS)诱变群体中鉴定到一个短宽粒突变体short and widen grain ...1(swg1);分析籽粒形态和其他农艺性状,并对颖壳进行组织细胞学观察分析;运用BSA法进行基因定位;通过遗传互补试验确定候选基因;采用qRT-PCR分析该基因的表达模式及其他粒型相关基因和细胞发育基因的表达水平.结果农艺性状分析发现,与野生型相比,swg1突变体粒长显著降低,粒宽显著增加,表现出短宽粒的表型;进一步组织和细胞学分析,发现突变体颖壳纵向细胞变短是粒长变短的主要原因,而粒宽增加是由于颖壳横向细胞数目和细胞大小同时增加.遗传分析结果表明,该突变性状受隐性单基因控制,通过图位克隆与遗传互补验证,确定候选基因为LOC-Os07g42410,编码一个植物特异转录因子.qRT-PCR分析发现该基因表达无明显的组织特异性,在茎、叶、幼穗中表达强烈.通过对已知粒型相关基因、细胞周期和细胞扩展相关基因进行分析,发现通过正向调控颖壳横向细胞数目和(或)细胞大小决定粒宽的GS5和GW8在突变体中上调明显,而正向调控纵向细胞数目和大小并负向调控横向细胞数目和大小的GW7/GL7在突变体明显下调;另外,部分与细胞周期和细胞扩展相关的基因也在突变体和野生型之间的表达也呈现显著差异.结论SWG1编码一个植物特异的转录因子,通过调控粒型基因(GS5、GW8和GW7/GL7等)影响颖壳的细胞增殖和细胞扩展,从而决定水稻籽粒长度和宽度.
Besides serving as promising candidates for realizing quantum computing, superconducting quantum circuits are one of a few macroscopic physical systems in which fundamental quantum phenomena can be ...directly demonstrated and tested, giving rise to a vast field of intensive research work both theoretically and experimentally. In this paper we report our work on the fabrication of superconducting quantum circuits, starting from its building blocks： Al/AlOx/Al Josephson junctions. By using electron beam lithography patterning and shadow evaporation, we have fabricated aluminum Josephson junctions with a controllable critical current density （jc） and wide range of junction sizes from 0.01 μm2 up to 1 μm2. We have carried out systematical studies on the oxidation process in fabricating Al/AlOx/Al Josephson junctions suitable for superconducting flux qubits. Furthermore, we have also fabricated superconducting quantum circuits such as superconducting flux qubits and charge-flux qubits.
The ecological protection and restoration of full-array ecosystems（mountains-rivers-forests-farmlands-lakes-grasslands） is an important part of ecological civilization construction. Thus, under the ...organizations of related ministries, a total of 25 ecological protection and restoration pilot projects have been implemented across 24 provinces since 2016. This paper analyzes the application of landsenses ecology theory for ecological protection and restoration of full-array ecosystems in the typical resource-exhausted city of Beipiao section, Daling River Basin. It also proposes the comprehensive management framework of ecological protection and restoration of full-array ecosystems in Beipiao, Daling River Basin. With the goal of maintaining, improving and improving ecosystem services, the framework designed a four-dimensional guidance of ″problem identification, system governance, natural restoration and landscape construction″ for ecological protection and restoration. Aiming at the typical key problems of ecological environment, such as a large number of industrial and mining wasteland, serious soil and water loss, water environment pollution and backward environmental infrastructure of villages and towns, the framework carry out the systematic management of full-array ecosystems with the watershed as the unit. In order to reduce the amount of project and capital investment, the method of ″rewilding″ is emphasized in the area dominated by natural ecosystem. In order to promote the effect of ecological protection and restoration, the theory and method of landsenses ecology are applied in the area where human activities are concentrated. The implementation path of the framework includes ecological security, ecological health and ecological well-being. Through the application of the meliorization model, the contents of ecological protection and restoration within the framework are constantly adjusted and optimized to achieve regional sustainable development. Aiming at maintaining and improving the important ecosystem services needed for sustainable development, the paper constructs the landsense creation system for ecological protection and restoration, as "one core, two key points, five elements and six projects". The study area is divided five main protection and restoration areas, which forms an ecological security pattern as "one belt and four districts". Finally, the paper puts forward the countermeasures and suggestions including: to construct the common behavior norms of regional residents, to guide and realize the beneficial impact of human beings on the natural ecosystem, and to further improve the effect of ecological protection and restoration of full-array ecosystems. Through the case study of Beipiao, Daling River Basin, the ecological protection and restoration of full-array ecosystems is carried out based on the concept of landsense creation, which provides ideas and ways to promote regional sustainable development.
We systematically investigate the influence of atomic potentials on the above-threshold ionization （ATI） spectra in one-dimensional （1D） cases and compare them with the three-dimensional （3D） case by ...numerically solving the time-dependent Schrrdinger equation. It is found that the direct ionization plateau and the rescattering plateau of the ATI spectrum in the 3D case can be well reproduced by the 1D ATI spectra calculated from the supersolid-core potential and the soft-core potential, respectively. By analyzing the factors that affect the yield of the ATI spectrum, we propose a modified-potential with which we can reproduce the overall 3D ATI spectrum. In addition, the influence of the incident laser intensities and frequencies on the ATI spectra calculated from the proposed modified potential is studied.
We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device（SQUID） detector are prepared by ...shadow evaporation with a suspended bridge. Al junctions with areas as small as 0.05 μm^2 are fabricated for the qubit, in which the number of the decoherencecausing two-level systems（TLS） residing in the tunnel barrier and proportional to the junction area are greatly reduced. The measured energy spectrum shows no avoided crossing arising from coherent TLS in the experimentally reachable flux bias range of the phase qubit, which demonstrates the energy relaxation time T1 and dephasing time Tφ on the order of 100 ns and 50 ns, respectively. We discuss several possible origins of decoherence from incoherent or weakly-coupled coherent TLS and further improvements of the qubit performance.
Deuterated potassium dihydrogen phosphate damage performance at 351 nm is studied on a large-aperture laser system. Bulk and rear-surface damage are initiated under the 3ω fluences of 6.T J/cm2 and ...33/cm2, and show different growth characteristics under multiple laser irradiations with the fluence of 6 J/cm2. The size and number of bulk damage keep unchanged once initiated. However, surface damage size also does not grow, while surface damage number increases linearly with laser shots. Different damage thresholds and growth behaviors suggest different formations of bulk and surface damage precursors. The cause of surface damage is supposed to be near-surface absorbing particles buried under the sol-gel coating.
We carry out an ultra-low-field nuclear magnetic resonance （NMR） experiment based on high-T c superconducting quantum interference devices （SQUIDs）. The measurement field is in a micro-tesla range ...（～10 μT-100 μT） and the experiment is conducted in a home-made magnetically-shielded-room （MSR）. The measurements are performed by the indirect coupling method in which the signal of nuclei precession is indirectly coupled to the SQUID through a tuned copper coil transformer. In such an arrangement, the interferences of applied measurement and polarization field to the SQUID sensor are avoided and the performance of the SQUID is not destroyed. In order to compare the detection sensitivity obtained by using the SQUID with that achieved using a conventional low-noise-amplifier, we perform the measurements using a commercial room temperature amplifier. The results show that in a wide frequency range （～1 kHz-10 kHz） the measurements with the SQUID sensor exhibit a higher signal-to-noise ratio. Further, we discuss the dependence of NMR peak magnitude on measurement frequency. We attribute the reduction of the peak magnitude at high frequency to the increased field inhomogeneity as the measurement field increases. This is verified by compensating the field gradient using three sets of gradient coils.
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