First principles calculation of ac conductance for Al-BDT-Al and Al-Cn-Al systems

We perform first-principles calculation to investigate the dynamic conductance of atomic wires of the benzenedithiol (BDT) as well as carbon chains with different length in contact with two Al(100) electrodes (Al-Cn-Al). Our calculation is based on the combination of the non-equilibrium Green's function and the density functional theory. For ac conductance, there are two theories that ensures the current conservation: (1). the global formula which is a phenomenological theory that partitions the total displacement current into each leads so that the current is conserved.(2). the local formula which is a microscopic theory that includes Coulomb interaction explicitly so that the current is conserved automatically. In this work, we use the local formula to calculate the dynamic conductance, especially the emittance. We give a detailed comparison and analysis for the results obtained from two theories. Our numerical results show that the global formula overestimates the emittance by two orders of magnitude. We also obtain an inequality showing that the emittance from global formula is greater than that from local formula for real atomic structures. For Al-Cn-Al structures, the oscillatory behavior as the number of carbon chain N varies from even to odd remains unchanged when local formula is used. However, the prediction of local formula gives rise to opposite response when N is odd (inductive-like) as compared with that of global formula. Therefore, one should use the local formula for an accurate description of ac transport in nanoscale structures. In addition, the ‘size effect’ of the ac emittance is analyzed and can be understood by the kinetic inductance. Since numerical calculation using the global formula can be performed in orbital space while the local formula can only be used in real space, our numerical results indicate that the calculation using the local formula is extremely computational demanding.published_or_final_versio

Wide-Range Tunable Dynamic Property of Carbon Nanotube-Based Fibers

Carbon nanotube (CNT) fiber is formed by assembling millions of individual tubes. The assembly feature provides the fiber with rich interface structures and thus various ways of energy dissipation, as reflected by the non-zero loss tangent (>0.028--0.045) at low vibration frequencies. A fiber containing entangled CNTs possesses higher loss tangents than a fiber spun from aligned CNTs. Liquid densification and polymer infiltration, the two common ways to increase the interfacial friction and thus the fiber's tensile strength and modulus, are found to efficiently reduce the damping coefficient. This is because the sliding tendency between CNT bundles can also be well suppressed by the high packing density and the formation of covalent polymer cross-links within the fiber. The CNT/bismaleimide composite fiber exhibited the smallest loss tangent, nearly as the same as that of carbon fibers. At a higher level of the assembly structure, namely a multi-ply CNT yarn, the inter-fiber friction and sliding tendency obviously influence the yarn's damping performance, and the loss tangent can be tuned within a wide range, as similar to carbon fibers, nylon yarns, or cotton yarns. The wide-range tunable dynamic properties allow new applications ranging from high quality factor materials to dissipative systems

Self-concept of gifted children aged 9 to 13 years old

Ninety-four gifted children and 200 nongifted children (aged 9 to 13 years old) were involved in the present study. Their self-concept was assessed by the Revised Song-Hattie Self-Concept Inventory (Zhou & He, 1996). Academic self-concepts pertaining to abilities, school achievements, and grade concepts and nonacademic self-concepts pertaining to family, peers, body, and self-confidence concepts, as well as self-concept in general, were considered in the present study. The findings indicated that the development of self-concept in gifted children was different from that of nongifted children.Specifically, the self-concept scores in general of nongifted children increased from 11 to 13 years old, while those of gifted children decreased for the same age period. Both academic and nonacademic self-concepts are discussed in the present study

Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites

High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20--50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27--6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117--192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals

A study of the Relationship Between the Microwave and Meter-Wavelength Emissions from the Solar Flare on June 3, 2021

We present the preliminary results of the flare analysis. The event took place on 3rd June 2021, at 01:36 UT. It was observed in microwaves by Siberian Radioheliograph (SRH) within the 3-6 GHz, Broadband Microwave Spectropolarimeter (BBMS) and in meter radio range by e-Callisto spectrograph network. We found several of the type III bursts and the type-J burst in the meter radio range. At the same time, only the one burst was detected in the averaged time profiles of microwaves emission. This one corresponds to the strongest type III radio burst. Using the images by SRH, we defined the two sources and analysis of the time profiles of them separately. This approach allowed us finding the microwave bursts associated with the radio bursts, which were not distinguished in averaged time profiles. The delays between microwave and meter radio emission obtained from observations were compared with the results of preliminary analysis of dynamic spectra in radio meter range

Optimization of breeding methods when introducing multiple resistance genes from American to Chinese wheat

Stripe rust is one of the most destructive diseases of wheat worldwide. Growing resistant cultivars with resistance genes is the most effective method to control this disease. QuLine is a computer tool capable of defining genetic models, breeding strategies and predicting parental selection using known gene information. This paper reports the breeding process for pyramiding resistance genes to stripe rust using genetic information of American cultivars Aplowa (P1), Louise (P2), Express (P3) and Chinese cultivar Zhoumai18 (P4). The breeding objective was to transfer the stripe rust (SR) resistance genes from the three American lines to the elite Chinese wheat, without reducing its desired agronomic performance (AT). Results show that double crosses (P4×P1)//(P4×P2), (P4×P1)//(P4×P3) and (P4×P2)//(P4×P3) were efficient in improving genetic gains on traits AT and SR in selection strategy AHA, while only in HAH, cross combination (P4×P3) // (P1×P2) had the highest genetic gains on high-temperature, adult-plant resistance (HTAP). The results in this study could be important in targeted breeding for efficiently pyramiding more resistance genes to stripe rust, avoiding simplified resistance genes, and breeding novel varieties.Key words: Breeding methods, wheat, resistance, genes

Cloning and characterization of a nitrite reductase gene related to somatic embryogenesis in Gossypium hirsutum

A nitrite reductase gene related to somatic embryogenesis was first cloned from Gossypium hirsutum. The cDNA sequence of the gene, named GhNiR, is 2,257 bp in length, with 254 bp of the 5’ untranslated region and 236 bp of the 3’ untranslated region. The open reading frame is 1,767 bp in length, encoding a deduced amino acid sequence of 588 residues with a molecular weight of 65.722 kDa and an isoelectric point of 7.07. Semi-quantitative RT-PCR analysis showed that the expression level of GhNiR was higher in embryogenic calli and somatic embryoids than in nonembryogenic calli among different somatic embryogenesis stages, and that the level of GhNiR mRNA was also higher in the cultivar with higher somatic embryogenesis ability. The catalytic GhNiR was verified by transformation in E. coli BL21 (DE3) strain with the recombinant expression vector pET-28A-GhNiR. NiR activity assay showedthat the crude GhNiR protein had obvious activity to NaNO2 substrate

Reactive oxygen species mediate TNFR1 increase after TRPV1 activation in mouse DRG neurons

<p>Abstract</p> <p>Background</p> <p>Transient receptor potential vanilloid subtype 1 (TRPV1) is activated by low pH/protons and is well known to be involved in hyperalgesia during inflammation. Tumor necrosis factor α (TNF-α), a proinflammatory cytokine, is involved in nociceptive responses causing hyperalgesia through TNF receptor type 1 (TNFR1) activation. Reactive oxygen species (ROS) production is also prominently increased in inflamed tissue. The present study investigated TNFR1 receptors in primary cultured mouse dorsal root ganglion (DRG) neurons after TRPV1 activation and the involvement of ROS. C57BL/6 mice, both TRPV1 knockout and wild type, were used for immunofluorescent and live cell imaging. The L4 and L5 DRGs were dissected bilaterally and cultured overnight. TRPV1 was stimulated with capsaicin or its potent analog, resiniferatoxin. ROS production was measured with live cell imaging and TNFR1 was detected with immunofluorescence in DRG primary cultures. The TRPV1 knockout mice, TRPV1 antagonist, capsazepine, and ROS scavenger, N-tert-Butyl-α-phenylnitrone (PBN), were employed to explore the functional relationship among TRPV1, ROS and TNFR1 in these studies.</p> <p>Results</p> <p>The results demonstrate that TRPV1 activation increases TNFR1 receptors and ROS generation in primary cultures of mouse DRG neurons. Activated increases in TNFR1 receptors and ROS production are absent in TRPV1 deficient mice. The PBN blocks increases in TNFR1 and ROS production induced by capsaicin/resiniferatoxin.</p> <p>Conclusion</p> <p>TRPV1 activation increases TNFR1 in cultured mouse DRG neurons through a ROS signaling pathway, a novel sensitization mechanism in DRG neurons.</p

Trace doping of multiple elements enables stable battery cycling of LiCoO2 at 4.6 V

LiCoO2 is a dominant cathode material for lithium-ion (Li-ion) batteries due to its high volumetric energy density, which could potentially be further improved by charging to high voltages. However, practical adoption of high-voltage charging is hindered by LiCoO2’s structural instability at the deeply delithiated state and the associated safety concerns. Here, we achieve stable cycling of LiCoO2 at 4.6 V (versus Li/Li+) through trace Ti–Mg–Al co-doping. Using state-of-the-art synchrotron X-ray imaging and spectroscopic techniques, we report the incorporation of Mg and Al into the LiCoO2 lattice, which inhibits the undesired phase transition at voltages above 4.5 V. We also show that, even in trace amounts, Ti segregates significantly at grain boundaries and on the surface, modifying the microstructure of the particles while stabilizing the surface oxygen at high voltages. These dopants contribute through different mechanisms and synergistically promote the cycle stability of LiCoO2 at 4.6 V

Surgery for Dupuytren’s contracture of the fingers (Review)

Background - Dupuytren's disease is a benign fibroproliferative disorder that causes the fingers to be drawn into the palm via formation of new tissue under the glabrous skin of the hand. This disorder causes functional limitations, but it can be treated through a variety of surgical techniques. As a chronic condition, it tends to recur. Objectives - To assess the benefits and harms of different surgical procedures for treatment of Dupuytren's contracture of the index, middle, ring and little fingers