多倍体植物混合倍性种群的建立机制研究进展

基因组多倍化是物种形成和进化的重要驱动力,几乎所有植物都经历过至少一次基因组加倍。然而,由于多倍体植株比二倍体表现出更高的死亡率,多倍化机制被认为是植物进化的"死胡同"。一些植物物种具有自然混合倍性种群,即同一物种具有不同倍性,这为揭示多倍体的进化机制提供了最佳途径。本文从基因组加倍形成多倍体植物开始,综述了混合倍性种群的形成、建立与维持的研究进展,探讨了多倍体适应自然环境的种群分化而形成多倍体物种的机制。研究自然混合倍性种群的倍性组成、重复基因的功能分化以及多倍体的生态位分化,有利于明确混合倍性自然种群的生态适应与维持机理,以及多倍体植物的进化机制。

The Alternative Mathematical Models of the World

The biggest insufficiency of the present mathematics is that it consists, in fact, of the eclectic mixture of two different models. In the first model, the world is taken as infinity and what is chosen as an element here is the unit. Everything is measured by the multiples of the unit. According to the second model, this world is in unity and its mathematical manifestation is the unit. The world is between zero and one. Everything here is measured by fraction The simplified variants of the mathematical model of the world paves the way for the comparative analysis of its alternative philosophical interpretations.

Facile synthesis of T-Nb_2O_5 nanosheets/nitrogen and sulfur co-doped graphene for high performance lithium-ion hybrid supercapacitors

Li-ion hybrid supercapacitors（Li-HSCs） have attracted increasing attention as a promising energy storage device with both high power and energy densities. We report a facile two-step hydrothermal method to prepare the orthorhombic niobium oxide（T-Nb2O5） nanosheets supported on nitrogen and sulfur co-doped graphene（T-Nb205/NS-G） as anode for Li-HSCs. X-ray diffraction and morphological analysis show that the T-Nb2O5 nano sheets successfully and uniformly distributed on the NS-G sheets. The T-Nb2O5/NS-G hybrid exhibits great rate capability（capacity retention of63.1% from 0.05 to 5 A g^-1） and superior cycling stability（a low capacity fading of ～6.4% after 1000 cycles at 0.5 A g^-1）.The full-cell consisting of T-Nb2O5/NS-G and active carbon（AC） results in high energy density（69.2 W h kg^-1 at0.1 A g^-1）, high power density（9.17 kW kg^-1） and excellent cycling stability（95% of the initial energy after 3000 cycles）.This excellent performance is mainly attributed to the highly conductive NS-G sheets, the uniformly distributed T-Nb2O5 nano sheets and the synergetic effects between them. These encouraging performances confirm that the obtained TNb2O5/NS-G has promising prospect as the anode for Li-HSCs.

Post-annealing tailored 3D cross-linked TiNb2O7 nanorod electrode: towards superior lithium storage for flexible lithium-ion capacitors

TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.

Filling and unfilling carbon capsules with transition metal oxide nanoparticles for Li-ion hybrid supercapacitors:towards hundred grade energy density

Li-ion hybrid supercapacitors （Li-HECs） facilitate effective combination of the advantages of supercapacitors and Li-ion batteries （LIBs）. However, challenges remain in designing and preparing suitable anode and cathode materials, which often require tedious and expensive procedures. Herein, we demonstrated that hollow N-doped carbon capsules （HNC） with and without a Fe304 nanoparticle core can respectively function as the anode and the cathode in very-high-performance Li-HECs. The Fe3Oa@NC anode exhibited a high reversible specific capacity exceeding 1530 mA h g^-1 at 100 mA g^-1 and excellent rate capability （45% capacity retention from 0.1 to 5 A g^-1） and cycle stability （〉97% retention after 100 cycles）. Moreover, high rate performance was achieved in a full-cell using the HNC cathode. By combining the respective structural advantages of the components, the hybrid device with Fe3Oa@NC//HN C exhibited a remark- able energy density of 185 W h kg^-1 at a power density of 39 W kg^-1. The hybrid device furnished a battery-inaccessible power density of 28 kW kg^-1 with rapid charging/discharging within 9 s at an energy density of 95 W h kg^-1.