Effect of space flight factors on alfalfa seeds

To explore the effect of space flight factors on the early development of alfalfa seedling, dry seeds were placed onboard a satellite for a 15-day flight. After retrieval, the ultra structure of seed coat and the chemical content of seed were tested, followed by tests for germinate ability, seedling growth, and mitotic and chromosome aberrations. Results showed that space flight factors have both positive and negative effects on alfalfa seeds. Positive effects include: (1) A 6.2% increase in germinate potential and (2) an 80% decrease in the number of hard seed in flight seeds. Meanwhile, negative effects included a decrease of 3.0 and 33.2% in the index of germination and vigor of flight seeds, respectively, which may be partly due to the inhibition of cell mitotic (26% less than ground control) and root growth (29.0% less than ground control) after the space flight. Moreover, the DNA and Ca2+ content of alfalfa seeds increased after the space flight, while the reserve energy content of alfalfa seeds, such as saccharine and fatty acid, decreased after the space flight. Conclusively, space flight factors accelerate the germination process of alfalfa seeds but restrain the root from growing due to chromosomal damage and abnormal mitosis induced by cosmic radiation.Key words: Alfalfa, space flight factors, germination, chromosome aberration

Tidal wind mapping from observations of a meteor radar chain in December 2011

This article proposes a technique to map the tidal winds in the mesosphere and lower thermosphere (MLT) region from the observations of a four-station meteor radar chain located at middle- and low-latitudes along the 120 degrees E meridian in the Northern Hemisphere. A 1month dataset of the horizontal winds in the altitude range of 80-100km is observed during December 2011. We first decompose the tidal winds into mean, diurnal, semidiurnal, and terdiurnal components for each station. It is found that the diurnal/semidiurnal components dominate at the low-latitude/midlatitude stations. Their amplitudes increase at lower altitudes and then decrease at higher altitudes after reaching a peak in the MLT region. Hough functions of the classical tidal theory are then used to fit the latitudinal distribution of each decomposed component. The diurnal component is found to be dominated by the first symmetric (1, 1) mode. Yet for the semidiurnal and terdiurnal components, the corresponding dominant modes are the second symmetric modes (2, 4) and (3, 5), and considerable contributions are also from the first antisymmetric modes (2, 3), (3, 4) and second antisymmetric modes (2, 5), (3, 6). Based on the decomposed results, we further map the horizontal winds in the domains of latitude, altitude and local time. The mapped horizontal winds successfully reproduce the local time versus altitudinal distributions of the original observations at the four stations. Thus, we conclude that the meteor radar chain is useful to monitor and study the regional characteristics of the tidal winds in the MLT region

The enhancement of electrochemical capacitance of biomass-carbon by pyrolysis of extracted nanofibers

Biomass-derived carbons have been extensively researched as electrode material for energy storage and conversion recently. However, most of the previous works convert crude biomass directly into carbon and the electrochemical capacitances for the resultant carbons are quite often underestimated as well as large variations in capacitances exist in literatures due to the complex nature of biomass, which practically hinder their applications. In this work, polysaccharide nanofibers were extracted from an inexpensive natural fungus using a hydrothermal method and were converted to porous carbon nanofibers (CNFs) by potassium hydroxide activation. The porous carbons were assembled into symmetric supercapacitors using both potassium hydroxide and an ionic liquid (IL) as electrolytes. Solid state nuclear magnetic resonance characterization showed that the micropores of the as-prepared carbons are accessible to the IL electrolyte when uncharged and thus high capacitance is expected. It is found in both electrolytes the electrochemical capacitances of CNFs are significantly higher than those of the porous carbon derived directly from the crude fungus. Furthermore, the CNFs delivered an extraordinary energy density of 92.3 Wh kg−1 in the IL electrolyte, making it a promising candidate for electrode materials for supercapacitors.<br/

Spinel photocatalysts for environmental remediation, hydrogen generation, CO₂ reduction and photoelectrochemical water splitting

The fundamental aspects, photocatalytic applications and ways to enhance the performance of spinels are systematically reviewed in this paper.</p

Superconductivity in a new layered cobalt oxychalcogenide Na6_{6}Co3_{3}Se6_{6}O3_{3} with a 3d5d^{5} triangular lattice

Unconventional superconductivity in bulk materials under ambient pressure is extremely rare among the 3$d$ transition-metal compounds outside the layered cuprates and iron-based family. It is predominantly linked to highly anisotropic electronic properties and quasi-two-dimensional (2D) Fermi surfaces. To date, the only known example of the Co-based exotic superconductor was the hydrated layered cobaltate, Na$_{x}$CoO$_{2}\cdot$ yH$_{2}$O, and its superconductivity is realized in the vicinity of a spin-1/2 Mott state. However, the nature of the superconductivity in these materials is still an active subject of debate, and therefore, finding new class of superconductors will help unravel the mysteries of their unconventional superconductivity. Here we report the discovery of unconventional superconductivity at $\sim$ 6.3 K in our newly synthesized layered compound Na$_{6}$Co$_{3}$Se$_{6}$O$_{3}$, in which the edge-shared CoSe$_{6}$ octahedra form [CoSe$_{2}$] layers with a perfect triangular lattice of Co ions. It is the first 3$d$ transition-metal oxychalcogenide superconductor with distinct structural and chemical characteristics. Despite its relatively low $T_{c}$, material exhibits extremely high superconducting upper critical fields, $\mu_{0}H_{c2}(0)$, which far exceeds the Pauli paramagnetic limit by a factor of 3 - 4. First-principles calculations show that Na$_{6}$Co$_{3}$Se$_{6}$O$_{3}$ is a rare example of negative charge transfer superconductor. This new cobalt oxychalcogenide with a geometrical frustration among Co spins, shows great potential as a highly appealing candidate for the realization of high-$T_{c}$ and/or unconventional superconductivity beyond the well-established Cu- and Fe-based superconductor families, and opened a new field in physics and chemistry of low-dimensional superconductors

Inhibition of Endothelial Cell Proliferation and Tumor Angiogenesis by Up-Regulating NDRG2 Expression in Breast Cancer Cells

The N-myc downstream-regulated gene 2 (NDRG2) is involved in tumor cell differentiation and apoptosis, but its function in tumor angiogenesis remains to be established. Here, we employed adenovirus overexpressing NDRG2 (Ad-NDRG2) to efficiently up-regulate target gene expression in the NDRG2-low-expressing, breast cancer cell line MCF-7. Moreover, VEGF secretion was decreased in MCF-7 cells infected by Ad-NDRG2, and medium conditioned by these infected cells could significantly inhibit the proliferation, tube formation and invasion of human umbilical vein endothelial cells (HUVECs). Further study indicated that the angiogenesis promoting factors VEGF and HIF-1α were down-regulated, whereas the angiogenesis suppressing factors p53 and VHL were up-regulated in MCF-7 cells infected by Ad-NDRG2. Finally, in a nude mouse model, intratumoral injections of Ad-NDRG2 every 3 days for 20 days significantly inhibited the growth and angiogenesis of xenografted MCF-7 tumors. In summary, these data indicate that NDRG2 may be involved in angiogenesis by impacting the expression of angiogenesis related factors. Thus, specific overexpression of NDRG2 by adenovirus represents a promising approach for the treatment of tumor angiogenesis

Label-free analysis of protein biomarkers using pattern-optimized graphene-nanopyramid SERS for rapid diagnosis of Alzheimer’s disease

The quantitative and highly sensitive detection of biomarkers such as Tau proteins and Aβ polypeptides is considered one of the most effective methods for the early diagnosis of Alzheimer’s disease (AD). Surface-enhanced Raman spectroscopy (SERS) detection is a promising method that faces, however, challenges like insufficient sensitivity due to the non-optimized nanostructures for specialized analyte sizes and insufficient control of the location of SERS hot spots. Thus, the SERS detection of AD biomarkers is restricted. We reported here an in-depth study of the analytical Raman enhancement factor (EF) of the wafer-scale graphene-Au nanopyramid hybrid SERS substrates using a combination of both theoretical calculation and experimental measurements. Experimental results show that larger nanopyramids and smaller gap spacing lead to a larger SERS EF, with an optimized analytical EF up to 1.1 × 1010. The hybrid SERS substrate exhibited detection limits of 10–15 M for Tau and phospho-Tau (P-Tau) proteins and 10–14 M for Aβ polypeptides, respectively. Principal component analysis correctly categorized the SERS spectra of different biomarkers at ultralow concentrations (10–13 M) using the optimized substrate. Amide III bands at 1200–1300 cm–1 reflect different structural conformations of proteins or polypeptides. Tau and P-Tau proteins are inherently disordered with a few α-helix residuals. The structure of Aβ42 polypeptides transitioned from the α-helix to the β-sheet as the concentration increased. These results demonstrate that the hybrid SERS method could be a simple and effective way for the label-free detection of protein biomarkers to enable the rapid early diagnosis of AD and other diseases