100,442 research outputs found
Critical Cation Balance In B-]Z Transition - Role Of Li+
No full textThe sodium salt of poly(dG-dC) is known to exhibit a B + Z transition in the presence of various cations and 60% alcohol. We here show that the lithium salt of poly(dG-dC) does not undergo B 4 Z transition in the presence of 60% alcohol since Li’ with its large hydration shell cannot stabilize the Z-form. On the other hand, high concentrations of Mg2* or micromolar concentrations of the cobalt hexamine complex which are known to stabilize the Z-form can compete with Li+ for charge neutraIization and hence bring about a B--t Z transition in the same polymer. From the model building studies the mode of action of the
cobalt-hexamine complex in stabilizing the Z-form is postulated
Critical cation balance in B → Z transition: role of Li+
No full textAbstractThe sodium salt of poly(dGdC) is known to exhibit a B → Z transition in the presence of various cations and 60% alcohol. We here show that the lithium salt of poly(dGdC) does not undergo B → Z transition in the presence of 60% alcohol since Li+ with its large hydration shell cannot stabilize the Z-form. On the other hand, high concentrations of Mg2+ or micromolar concentrations of the cobalt hexamine complex which are known to stabilize the Z-form can compete with Li+ for charge neutralization and hence bring about a B → Z transition in the same polymer. From the model building studies the mode of action of the cobalt—hexamine complex in stabilizing the Z-form is postulated
Mid-infrared polarization spectroscopy: a tool for in situ measurements of toxic gases in smoke-laden environments
No full textAbstract not availableZ. W. Sun, M. Försth, Z. S. Li, B. Li, and M. Aldé
The full gradient design in Li-rich cathode for high performance lithium ion batteries with reduced voltage decay
No full textLi-rich nickel cobalt manganese oxides (LNCM) cathode with full gradient compounds is prepared by using an ethanol assisted co-precipitation method. The rationally designed procedure involves gradient distributions of transition-metal ions, in which the Ni content increases continuously, Mn content decreases gradually and Co keeps at a low level. The employing ethanol during the synthesis adjusts the surface state to further improve the rate performance of the sample. The full gradient cathode not only provides superior cycling capacity, but also improves operating voltage and mitigates voltage decay due to the high Ni/Mn ratio of out layer with decreased Li2MnO3. The prepared material exhibits high specific capacity of 213.1 mAh g−1 after 100 cycling with voltage decay per cycle about 3.36 mV at 1 C. Even more notably, the voltage decay during cycling could still be significantly limited at high rates and capacity retention rates of 84% and 75% can be reached after 100 cycling at 2 C and 5 C, respectively. Hence, this state-of-art full gradient cathode provides an interesting model to promote a further application of LNCM
Genome sequences of five Sitopsis species of Aegilops and the origin of polyploid wheat B subgenome
No full textCommon wheat (Triticum aestivum, BBAADD) is a major staple food crop worldwide. The diploid progenitors of the A and D subgenomes have been unequivocally identified; that of B, however, remains ambiguous and controversial but is suspected to be related to species of Aegilops, section Sitopsis. Here, we report the assembly of chromosome-level genome sequences of all five Sitopsis species, namely Aegilops bicornis, Ae. longissima, Ae. searsii, Ae. sharonensis, and Ae. speltoides, as well as the partial assembly of the Amblyopyrum muticum (synonym Aegilops mutica) genome for phylogenetic analysis. Our results reveal that the donor of the common wheat B subgenome is a distinct, and most probably extinct, diploid species that diverged from an ancestral progenitor of the B lineage to which the still extant Ae. speltoides and Am. muticum belong. In addition, we identified interspecific genetic introgressions throughout the evolution of the Triticum/Aegilops species complex. The five Sitopsis species have various assembled genome sizes (4.11–5.89 Gb) with high proportions of repetitive sequences (85.99%–89.81%); nonetheless, they retain high collinearity with other genomes or subgenomes of species in the Triticum/Aegilops complex. Differences in genome size were primarily due to independent post-speciation amplification of transposons. We also identified a set of Sitopsis genes pertinent to important agronomic traits that can be harnessed for wheat breeding. These newly assembled genome resources provide a new roadmap for evolutionary and genetic studies of the Triticum/Aegilops complex, as well as for wheat improvement. © 2022 The Autho
Heterogeneous oxidation involving different atomic clusters in sintering-free amorphous SiBCN ceramic with MA@PDC-SiBCN structure
No full textAmorphous SiBCN monoliths featuring a structure of three-dimensional PDC-SiBCN network encapsulating MA-SiBCN nanoparticles (MA@PDC-SiBCN), were prepared without the need for sintering densification (>1800 °C), enabling preparation of dense ceramics at a much lower temperature (1100 °C). The continuous PDC-SiBCN network effectively inhibits oxygen diffusion, reducing the mass loss from B–C–N cluster oxidation and mass gain from silicon-containing clusters by 51.5 % and 86.9 %, respectively. Besides, the phase-separation coupled heterogeneous oxidation behaviors and kinetics of different atomic clusters in MA@PDC-SiBCN ceramic during non-isothermal oxidation up to 1500 °C were investigated. Finally, the evolution of the different atomic clusters within the oxide layer during the heterogeneous oxidation process was analyzed to elucidate the micro-mechanisms behind the enhanced oxidation resistance
Experimental study on dynamic characteristics of rubber sand mixtures
No full textAs a new type of environmentally friendly lightweight composite material, rubber sand mixture has a wide application prospect in the field of engineering vibration isolation. In order to reveal the variation law of dynamic characteristics of different rubber sand mixtures, based on the dynamic triaxial test, the effects of rubber content and confining pressure on the backbone curve, dynamic shear modulus and damping ratio of mixtures were studied. The results showed that with an increase in the rubber content, the backbone curve of rubber sand mixture had a trend of ' ductile failure ' and the dynamic shear modulus of mixture decreased. The nonlinear coordinated variation could be found between the damping ratio and rubber content with a characteristic threshold of 40 %. The mechanical properties of rubber particles may be influenced by changing the type of ' skeleton structure' inside the sample
Analysis of generation and propagation mechanism of supraharmonic in grid-connected inverter|并网逆变器超高次谐波产生与传播机理分析
No full textSupraharmonics are a new power quality prohlem that fan not he ignored in new energy power generation technology. As a typical supraharmonic source.the grid-connected inverter has received extensive attentions. To reveal the characteristics of its generation and propagation mechanism, the mechanism of supraharmonic generation in sinusoidal pulse width modulation (SPWM) inverters is analyzed firstly. Ii is found that the supraharmonics generated are mainly distrihuted around integer multiples of the switching frequency.and can he equivalent to a voltage source. At the same time.the influencing factors that cause changes in the voltage source are theoretically analyzed. Then.a supraharmonic circuit model including inverter.filter and grid side impedance is established, and the mathematical expression of supraharmonic emission current is derived. On this hasis.the influence of capacity and numher of inverters on supraharmonic propagation characteristics when multiple inverters are connected in parallel is explored through the control rariates. Finally,the simulation experiment is carried out in Simulink. The results show that supraharmonics in the grid-connected inverter are mainly affected hy the DC side voltage and modulation ratio, and the emission intensity of supraharmonics is proportional to the capacity when multiple inverters operate in parallel. The correctness of the theoretical analysis of supraharmonics in the grid-connected inverter is verified in this paper
Interspecific competition between Diadegma semiclausum Hellen (Hym., Ichneumonidae) and Cotesia plutellae (Kurdjumov) (Hym., Braconidae) in parasitizing Plutella xylostella (L.) (Lep., Plutellidea)
No full text- …
