ALBERT

Description: A large continental normal-faulting earthquake occurred in the Yinchuan Graben in northern China on 3rd January 1739. This event is of significant interest for two reasons. Firstly, it has been suggested on the basis of historical records of shaking that this was a magnitude 8.0 event. If this is true, the 1739 earthquake would be one of the largest continental normal-faulting earthquakes ever recorded and this should prompt us to consider the factors contributing to its unusual size. Secondly, there has been some debate in the literature about the causative structure, with at least three different faults posited as the seismogenic source. We use five 14 C ages to date a series of scarps on the East Helanshan Fault, which lies to the west of the graben, and bracket the scarp formation to the last 350 years. We use high-resolution, stereo imagery from the Pleiades satellites to build a 1 to 2 m resolution DEM of the fault and combine this with field observations to map the East Helanshan rupture in detail. We then construct a throw distribution, determine the slip vector azimuth and re-assess the earthquake magnitude using simple scaling relationships. We conclude that the 1739 earthquake occurred on the East Helanshan Fault, had a rupture length of approximately 87 km, a maximum throw of 5.1 m and an average throw of 3.0 m, yielding a best estimate magnitude in the range M w  7.1 to M w  7.6. We suggest that the previous magnitude estimates are biased by enhanced shaking of the sediments within the Yinchuan Graben.

Description: Zirconium diboride (ZrB 2 ) ceramic matrix composites reinforced by silicon carbide platelets (SiC pl ) were prepared by hot pressing. Five groups of specimens were prepared, in which the contents of SiC platelets were 0, 5, 10, 15 and 20 vol%, respectively. The oxidation behaviors of specimens at different temperatures from 800° to 1600°C for 1 h and at 1200°C for different times from 0.5 to 4 h were investigated. With the increase of SiC pl content, the mass gain exhibited a decreasing trend. Oxidation thermodynamics and kinetics of the SiC pl /ZrB 2 composites were discussed. A characteristic structure of hollow quadrangular prismy ZrO 2 crystal emerged on the sample surface after oxidation was found and the possible formation mechanism was also presented. The surface element analysis indicated that the main products of oxidation were m -ZrO 2 , SiO 2 , and borosilicate (aluminosilicate).

Description: Four compounds with similar structures and UV spectra were isolated from the fermentation broth of Armillaria mellea by means of preparative HPLC. Their structures were established as methyl (2 S )-1-[2-(furan-2-yl)-2-oxoethyl]-5-oxopyrrolidine-2-carboxylate ( 1 ), (2 S )-1-[2-(furan-2-yl)-2-oxoethyl]-5-oxopyrrolidine-2-carboxylic acid ( 2 ), 1-[2-(furan-2-yl)-2-oxoethyl]pyrrolidin-2-one ( 3 ) and 1-[2-(furan-2-yl)-2-oxoethyl]piperidin-2-one ( 4 ) on the basis of their 1D- and 2D-NMR, and HR-MS data. The absolute configurations of compounds 1 and 2 were determined by comparison of the experimental and calculated electronic circular dichroism (ECD) data. Additionally, four known compounds, 5 – 8 , were also isolated.

Description: One new anthracene derivative, juglanthracenoside A ( 1 ), two new anthraquinones, juglanthraquinone A ( 2 ) and juglanthraquinone B ( 3 ), along with a new naturally occurring anthraquinone, 9,10-dihydro-4,8-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid ( 4 ), have been isolated from the stem bark of Juglans mandshurica. Their structures were established by detailed spectroscopic analysis and comparison of the NMR data with those of related compounds. Compound 1 displayed noticeable antioxidant activity in both 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical-scavenging assays, while compound 4 showed strong cytotoxicity against HepG2, SGC7901, HCT-8, and A549 cell lines in vitro.

Description: This study investigates the Wangfu depression of the Songliao Basin, China, as a natural analogue site for Fe migration (bleaching) and mineralization (formation of iron concretions) caused by reducing CO 2 -bearing fluids that leak along fractures after carbon capture, utilization, and storage. We also examined the origin of fracture-filling calcite veins, the properties of self-sealing fluids, the influence of fluids on the compositions of mudstone, and established a bleaching model for the study area. Our results show that iron concretions are the oxidative products of precursor minerals (pyrite and siderite) during uplift and are linked to H 2 S and CO 2 present in early stage fluids. The precipitation of calcite veins is the result of CO 2 degassing and is related to CO 2 , CH 4 , and minor heavy hydrocarbons in the main bleaching fluids. In our model, fluids preferentially enter high-permeability fracture systems and result in the bleaching of surrounding rocks and precipitation of calcite veins. The infilling of calcite veins significantly decreases the permeability of fractures and forces the fluids to slowly enter and bleach the mudstone rocks. The Fe 2+ released during bleaching migrates to elsewhere with the solutions or is re-precipitated in the calcite veins and iron concretions. The formation of calcite veins reduces the fracture space and effectively prevents fluid flow. The fluids have an insignificant effect on minerals within the mudstone. In terms of the chemistry of the mudstone, only the contents of Fe 2 O 3 , U, and Mo change significantly, with the content of U increasing in the mudstone and the contents of Fe 2 O 3 and Mo decreasing during bleaching. This article is protected by copyright. All rights reserved.

Description: Reactions of Cd(NO 3 ) 2 · 4H 2 O with 2-quinolinecarboxylic acid (H-QLC) in the presence of 1,4-benzenedicarboxylic acid (H 2 -BDC) or 1,3,5-benzenetricarboxylic acid (H-BTC) in DMF/H 2 O solvent afforded two compounds, namely, [Cd(QLC)(BDC) 1/2 (H 2 O)] n ( 1 ) and [Cd(QLC)(BTC) 1/3 ] n ( 2 ). Both compounds are two-dimensional (2D) frameworks but feature different cadmium-carboxylate clusters as a result of the presence of the polycarboxylate ligands with different geometries and coordination preference. The dinuclear Cd 2 (QLC) 2 units in 1 are bridged by the pairs of bridging water ligands to give a one-dimensional (1D) chain, which is further linked by the second ligand of BDC 2– to form a 2D structure. Compound 2 is constructed from unique hexanuclear macrometallacyclic Cd 6 (QLC) 6 clusters, which are linked by the surrounding BTC 3– ligands to generate a 2D structure. Photoluminescence studies showed both compounds exhibit ligand-centered luminescent emissions with emission maxima at 405 and 401 nm, respectively.

Description: The microstructure, mechanical, and thermal properties of in situ hot-pressed 30 vol% ( ZrB 2 + ZrC )/ Zr 3 [ Al ( Si )] 4 C 6 composite have been investigated and compared with monolithic Zr 3 [ Al ( Si )] 4 C 6 ceramic. The composite is composed of ZrB 2 and ZrC grains embedded in a Zr 3 [ Al ( Si )] 4 C 6 matrix. The composite shows superior hardness (Vickers hardness of 16.4 GPa), stiffness (Young's modulus of 415 GPa), strength (bending strength of 621 MPa), and toughness (fracture toughness of 7.37 MPa·m 1/2 ) compared with monolithic Zr 3 [ Al ( Si )] 4 C 6 . The composite retains high modulus of 357 GPa at 1430°C (86% of that at ambient temperature) due to clean grain boundaries with no glassy phase. In addition, the composite exhibits higher specific heat capacity and thermal conductivity but slightly lower coefficient of thermal expansion compared with monolithic Zr 3 [ Al ( Si )] 4 C 6 . The calculation of the thermal stress fracture resistance parameter ( R ) predicts a much improved thermal shock resistance of the composite. Based on these results, ( ZrB 2 + ZrC )/ Zr 3 [ Al ( Si )] 4 C 6 composites show promising potential for high-temperature and ultra high-temperature applications.

Description: [1]  The patterns, components and controls of soil respiration in an old-growth subtropical forest were investigated by using an automatic chamber system. We measured soil respiration in three treatments (control, trenching, litter removal) over 15 months. The annual total soil respiration (1248 gC m -2  yr -1 ) showed considerable spatial variation (coefficient of variation = 27.8%) within the forest. Thirty samples were required to obtain results within 10% of the mean value at a 95% confidential level. A distinctive cosine-like diel pattern of soil respiration was observed; the time lag between gross primary production and soil respiration at this scale was calculated to be 4–5 h. Seasonality of soil respiration was strong (~1  μ mol m -2  s -1 near the end of winter; ~6  μ mol m -2  s -1 in mid-summer). No time lag was discerned between gross primary production and soil respiration at the seasonal scale. Soil temperature at 5 cm below surface can explain most (〉91%) of the observed annual variation in soil respiration. The apparent respiration temperature sensitivity index ( Q 10 ) was 3.05. The lowest Q 10 value was observed in winter, when soil moisture was low. Soil respiration was overestimated by a Q 10 function during both dry and wet periods. The relative contributions of soil organic matter ( R SOM ), litterfall decomposition ( R L ), and root respiration ( R R ) to total soil respiration are 65.25%, 18.73%, and 16.01%, respectively; the temperature sensitivity of these components differ: R L ( Q 10  = 7.22) 〉  R SOM (2.73) 〉  R R (1.65). This relationship between Q 10 values for litter respiration, soil organic matter decomposition and root respiration still holds after minimizing the confounding effect of moisture. A relatively constant substrate supply and/or thermal acclimation could account for the observed low temperature sensitivity in root respiration. Given the high carbon stocks and fluxes, the old-growth subtropical forests of China seem important in the global carbon budget and climate change.

Description: Abstract Using the in‐situ measurements of ROCSAT‐1 satellite during 181 geomagnetic storms happened from July 1999 to June 2004, a superposed epoch analysis (SEA) of the equatorial plasma depletions (EPDs) occurrence is conducted. At Post‐sunset hours (1800‐2200 LT), the EPDs occurrence is enhanced shortly at the storm onset, but afterwards, a long‐last suppression dominates. The EPDs occurrence at Midnight (2200‐0200 LT) generally shares a similar pattern to that at Post‐sunset hours. The occurrence at Pre‐dawn (0200‐0400) gradual increases near storm onset and reach its maximum at 6~9 h and decays until 18 h. For a given longitude at Post‐sunset/Midnight, the EPDs occurrence tends to be suppressed or promoted when the EPDs do or do not prevail. The disturbed vertical plasma drift generally determines the inhibition/promotion of the EPDs occurrence at Post‐sunset/Pre‐dawn. However, for Pre‐dawn EPDs occurrence, the plasma vertical drift cannot well explain the longitudinal variation. The continuous observations from consecutive orbits of ROCSAT‐1 are carefully compared and the result suggests that the geomagnetic storm‐induced additional Pre‐dawn EPDs are preferred to be the longer‐lived developed EPDs rather than fresh EPDs. In addition, a possible mechanism concerning the background plasma density enhancement which might be related with the energetic electrons induced nighttime ionization is proposed.

Description: This study aimed to investigate the molecular mechanism of dehydroepiandrosterone (DHEA) rehabilitated BRL-3A cells oxidative stress damage induced by hydrogen peroxide (H 2 O 2 ). Results showed that DHEA reversed the decrease of cell viability and ameliorated nuclear chromatin damage in H 2 O 2 -induced BRL-3A cells. DHEA increased the activities of superoxide dismutase, catalase, peroxidase, and glutathione peroxidase, and decreased the reactive oxygen species (ROS) production in H 2 O 2 -induced BRL-3A cells. DHEA attenuated the protein damage and lipid peroxidation, and reduced the apoptosis in H 2 O 2 -induced BRL-3A cells. The mRNA levels of Bax , Caspase-9 , and Caspase-3 were decreased, while the Bcl-2 mRNA level was increased in H 2 O 2 -induced BRL-3A cells treated with DHEA. Our results showed that DHEA treatment increased the PI3K and p-Akt protein levels, while decreased the Bax and capase-3 protein levels in H 2 O 2 -induced BRL-3A cells. However, the rise in PI3K and p-Akt protein levels, and the decrease in Bax and capase-3 protein levels induced by DHEA treatment were reversed when the cells pretreated with LY294002 (PI3K inhibitor). These results indicated that DHEA ameliorated H 2 O 2 -induced oxidative damage by increasing anti-oxidative enzyme activities and ameliorating the protein damage and lipid peroxidation in BRL-3A cells. In addition, DHEA decreased the apoptosis by inhibiting caspase-3 and Bax protein levels and this action mainly achieved via the activation of PI3K/Akt signaling pathways in H 2 O 2 -induced BRL-3A cells. These results provided substantial information for DHEA as a nutritional supplement to treat oxidative stress and it related diseases in animals and humans. Our results demonstrated that DHEA increased the cellular anti-oxidative enzyme activities and inhibited the apoptosis through activating the PI3K/Akt signaling pathways in H2O2-induced BRL-3A cell. In consideration of remarkable repaired effect of DHEA on H2O2-induced BRL-3A cell oxidative stress and apoptosis, our findings shed light on the potential application for DHEA in treatment of oxidative stress-induced liver injury.