ALBERT

Description: The four new cerebrosides 1 – 4 possessing a unique C 18 9-methylsphinga-4,8-dienine-related moiety and a cyclic octapeptide, 5 , possessing alternating proline and glycine moietes were isolated from the Tuber indicum fermentation mycelium. Their structures were established on the basis of a spectroscopic analysis including NMR and HR-ESI-MS, as well as an acidic methanolysis experiment. To the best of our knowledge, the cerebrosides identified in the present study are quite different from those isolated from Tuber indicum fruiting bodies. Additionally, it was the first time that a cyclic peptide was isolated from the Tuber genus.

Description: Nineteen compounds mainly including pyrrole-containing alkaloids and phytosterols were isolated from the EtOH extract of the fermented mycelia of Xylaria nigripes , a precious medicinal fungus known as Wuling Shen in Chinese. On the basis of spectroscopic methods, the structures of the new naturally occurring compounds were determined to be (4 S )-3,4-dihydro-4-(4-hydroxybenzyl)-3-oxo-1 H -pyrrolo[2,1- c ][1,4]oxazine-6-carbaldehyde ( 1 ), methyl (2 S )-2-[2-formyl-5-(hydroxymethyl)-1 H -pyrrol-1-yl]-3-(4-hydroxyphenyl)propanoate ( 2 ), and 3-{4-[(2 R )-(2,3-dihydroxy-3-methylbutoxy]phenyl}-7-hydroxy-4 H -chromen-4-one ( 3 ), respectively. The absolute configurations of 1 and 2 were deduced by the observed Cotton effects in their circular dichroism (CD) spectra, whereas that of the 1,2-diol moiety in 3 was determined using the Snatzke 's method. Their biological activities such as neuroprotective, anti-neuroinflammatory, and cytotoxic properties were also reported.

Description: Global warming poses a great threat to wetland ecological stability and water quality improvement. In this paper, we sampled six types of wetlands representing different land utilization around the TaiHu Lake Basin in Southeast China. An outdoor computerized microcosm was setup in May of 2008 to simulate climate scenarios of ambient temperature (control) and a warmed ambient temperature (+5 o C) using a novel minute-scale daily and seasonal temperature manipulation technology. The 18-month incubation indicated that warming impaired the ecological sink of sediment (fixing P from porewater) while strengthening the role of the ecological source, moreover, the rate of P release from sediment into porewater (19% to 113% for total phosphorus) was much stronger than from top sediment into overlying water. Warming enhanced the activity of neutral and alkaline phosphatases for P-deficient wetland sediments and neutral phosphatases for P-rich sediments, at the 14 th month of incubation. A significant increase in total phospholipid fatty acids (PLFAs) occurred under warming in sediments with relatively low levels of PLFAs, but bacterial abundance in the sediment biomass tended to decrease (18%) along with an increase (4.5%) of the fungi to bacteria ratio. The variations of carbon consumption and availability indicated by measured dissolved organic carbon in sediment may have contributed to P release from sediments to water. Copyright © 2011 John Wiley & Sons, Ltd.

Description: Two new silver(I) 3D coordination polymers, namely [Ag 3 (2-stp)(dpa)] n ( 1 ) and {[Ag 2 (2-stp)(H 2 O)]⋅Hdpa} n ( 2 ) (2-NaH 2 stp=sodium 2,5-dicarboxysulfonate, dpa=di(pyridine-2-yl)amine) were synthesized. The complexes were characterized by elemental analysis, FT-IR spectra, thermogravimetric analyses (TGA), and single-crystal X-ray diffraction. In complex 1 , three neighboring Ag ions are bridged by N- and O-atom, forming a 3D coordination network. The molecular structure of 2 is cation anion species, forming 3D host guest supramolecular network with the [Hdpa] + cations encapsulated in the nanochannels. The photoluminescence properties of the complexes were also investigated in the solid state at room temperature.

Description: Gas-phase heats of formation (HOF), solid-phase HOF, detonation properties, electronic structure and thermal stability for a series of polynitro pyrazine derivatives containing three heterocycles have been investigated using density functional theory. It is found that the nitro group is an efficient tool to improve HOF of pyrazine derivatives. Furthermore, detonation velocities and detonation pressures of these compounds are evaluated using empirical Kamlet–Jacobs equations. As a result, it indicates that the nitro group is useful to enhance detonation properties. Detonation velocities of five compounds are 9.67, 9.20, 9.74, 9.76 and 9.87 km/s, respectively, which are significantly larger than that of HMX (9.10 km/s). Bond dissociation energy is also performed to investigate their thermal stability , showing that thermal stability of these compounds is little affected by nitro groups or the position of substituent groups. Considering solid-phase HOF, detonation properties and thermal stability , some of pyrazine derivatives can be potential high energy density materials. Copyright © 2013 John Wiley & Sons, Ltd. High energy density materials (HEDMs) have been widely used for military and civil applications. However, current HEDMs cannot meet the increasing requirements. It is well-known that pyrazine derivatives are promising potential candidates of HEDMs. In this work, three series of pyrazine derivatives containing three heterocycles have been designed and theoretically investigated. Calculations show that these compounds have high positive heats of formation, powerful detonation properties and thermal stability.

Description: To evaluate the role of subducted oceanic crust in the genesis of potassium-rich magmas, we report high-precision Mg isotopic data for a set of Cenozoic volcanic rocks from Northeast China. These rocks overall are lighter in Mg isotopic composition than the normal mantle, and display considerable Mg isotopic variations, with δ 26 Mg ranging from -0.61 to -0.23. The covariation of δ 26 Mg with TiO 2 in these rocks suggests their light Mg isotopic compositions were derived from recycled oceanic crust in the form of carbonated eclogite in the source region. The strong correlations between δ 26 Mg and (Gd/Yb) N ratio as well as Sr-Pb isotopes further indicate a multicomponent and multistage origin of these rocks. Magnesium isotopes may thus be used as a novel tracer of recycled oceanic crust in the source region of mantle-derived magmas.

Description: ABSTRACT It was found that the expression level of miR-147a was significantly increased and the pathway of PI3K/AKT was dramatically inhibited after radiation. In view of the relationship between miRNA and target genes, we put forward the question, what is the relationship between PI3K /AKT and miR-147a? In order to find the answer to the question, we used bioinformatics techniques to analyze the relationship between miR-147 (a or b) and PI3K/AKT signaling pathway. miR-147a overexpression plasmid and PDPK1 3'UTR luciferase reporter gene plasmid were constructed. Dual luciferase reporter gene system validation experiments were carried out on miR-147a and PDPK1 relationship. The verification experiments were also carried out. Bioinformatics analysis showed that there is a miR-147a binding site in the non-coding region (3'UTR) of PDPK1. In the experimental groups transfected with wild type PDPK1 gene of 3'UTR plasmid, the luciferase activity decreased (or increased) significantly in miR-147a(or inhibitor) group compared with miR-NC(or anti-miR-NC); There was no significant difference between the miR-147a group(or inhibitor) and the miR-NC group(or anti-miR-NC) in the transfection of PDPK1-3'UTR-Mut gene vector. PDPK1 was a target gene for direct regulation of miR-147a downstream. Verifying test results showed that the expression of PDPK1 mRNA and protein was reduced after overexpression of miR-147a, which was up-regulated after silencing miR-147a in TC and V79 cells. These results suggest that miR-147a could be involved in the regulation of PDPK1 transcription by binding to the target site in PDPK1 mRNA 3'UTR, and then regulated AKT. This article is protected by copyright. All rights reserved

Description: Intermolecular interactions and properties of octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazocine (HMX) / 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) cocrystal were studied by using the dispersion-corrected density functionals (ωB97XD, B97D) and meta-hybrid functional (M062x) methods. Binding energies, heats of formation, thermodynamic properties, atoms in molecules, and natural bond orbital analysis were performed to investigate HMX/LLM-105 complexes. Results show that the main intermolecular interactions between HMX and LLM-105 are CH…O, NH…O, N…O, and O…O interactions. In addition, Monte Carlo simulation was employed to predict the crystal structure of HMX/LLM-105 cocrystal. The HMX/LLM-105 cocrystal is most likely to crystallize in C 2/c space group, and its corresponding cell parameters are Z = 8, a = 41.63 Å, b = 6.77 Å, c = 45.63 Å, ß = 164.55°, and ρ = 1.99 g/cm 3 . Detonation velocity and pressure of HMX/LLM-105 cocrystal are 8.95 km/s, 37.69GPa, a little lower than those of HMX (9.10 km/s, 37.76GPa). However, according to the net charges of nitro group, HMX/LLM-105 cocrystal exhibits less sensitive than HMX. Finally, bond dissociation energy calculation shows that HMX/LLM-105 complexes are thermally stable. Considering thermal stability , sensitivity, and detonation performance, HMX/LLM-105 cocrystal meets the requirements of insensitive high energy density materials. Copyright © 2013 John Wiley & Sons, Ltd. Previous studies have shown that cocrystal explosive is one of the most promising approaches to decrease sensitivity of high energy materials and maintain their detonation performance. In this work, a novel cocrystal composed of HMX and LLM-105 was designed and theoretically investigated. Calculation shows that HMX/LM-105 cocrystal possesses strong intermolecular interactions, insensitivity, thermal stability, and good detonation performance.

Description: [1]  We studied the ULF waves with a period of 30s in the ion diffusion region of reconnection observed by Cluster satellites on 21 August 2002. The fast convective tailward ion flow accompanied with large southward magnetic field component, strong Hall magnetic field and Hall electric field demonstrate that Cluster satellites are located in the ion diffusion region of reconnection. The analyses of wave properties using MVA and timing method indicate that this wave is a obliquely propagating slow magnetosonic wave which is characterized by the anti phase relation between the magnitude of magnetic field and the ion number density, and a propagation angle of around 130° with respect to the ambient magnetic field. This wave is generated by periodic magnetic reconnection. The periodic oscillations in B y and B x components are driven by the periodic Hall current system, while the oscillation in B z component is driven by quasi periodic convective tailward ion flows. The slow magnetosonic wave significantly influences the frequency of whistler waves and low hybrid waves excited by magnetic reconnection by changing the magnitude of local magnetic field and subsequently electron cyclotron frequency.

Description: Here, to assess the contribution of gravel bedload on the removal of attached-algae and aquatic plants from a cobble-bed river during small floods, we propose a geophone type method for measuring the local bedload of non-uniform sized gravel. Due to limited peak discharge for focused events during our study, a large fraction of bed material (here cobbles) was immobile and only a small fraction of bed material (sand and gravel) was expected to be transported during the flushing flows we analyzed. The device we developed has a size equivalent to immobile bed material and a shape similar to bed material (rounded cobbles) at the site. The instrument's design allows avoidance of disturbances in river bed micro-topography during installation and local bedload transport during floods. A flume experiment was conducted in order to establish an empirical algorithm for estimating the diameter of impacted gravel and, here, discuss uncertainty related to diameter estimations. The proposed method was utilized to quantify gravel bedload in a cobble-bed river during flushing flows. In the text, we also discuss the contribution of measured gravel bedload during flushing flows on the removal of attached-algae (up to a 37% reduction in chlorophyll-a density) and aquatic plants (a reduction of 38% in dry mass per area). Based on time variation for the measured gravel bedload, we also suggest the propagation of a bed-form composed of the fine sediment fraction migrating on immobile larger sediment and implications for the propagation of the fine sediment wave for attached-algae removal. This article is protected by copyright. All rights reserved.