Search

For the poor capacity utilization and insufficient cyclability of TiO 2 /C anodes for lithium-ion batteries, we synthesized branch-like TiO 2 @mesoporous carbon nanofibers (TiO 2 @MCNFs) as free-standing anodes via electrospinning technique, hydrothermal treatment and a subsequent carbonization process, where anatase TiO 2 branches were densely embedded on the mesoporous carbon nanofiber trunks. Due to the copious highly-exposed TiO 2 nanocrystal lattices on the branch except for the trunk support, the abundant intrinsic crystal channels for fluent Li + transportation, and the interlaced carbon nanofiber framework with a high structural integrity and mechanical flexibility, the branch-like TiO 2 @MCNFs composites presented a superior initial discharge capacity of 1932 mAhg −1 and an excellent reversible capacity of ∼617 mAhg −1 after 100 cycles. And compared with those of the reported TiO 2 /C electrodes, the initial discharge capacity and reversible capacity of the branch-like TiO 2 @MCNFs composites increased by ∼2 times and ∼50%, respectively. Hence, the unique architecture of the branch-like TiO 2 @MCNFs composites and their superior electrochemical performances may provide new insights for the development of better host materials for practical lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Recently, carbon nanofibers@TiO 2 (CNFs@TiO 2 ) composites as photocatalysts for dye degradation have attracted intense attention. However, only few contributions had been made to investigate systematically the differences between the various preparation approaches and the influence of thermal treatment on the photocatalytic activity. In this work, the electrospun CNFs@TiO 2 composites which were prepared by hydrothermal reaction and blended spinning, respectively, have been fabricated via stabilization in air at 280 °C and then carbonization in N 2 at heat treatment temperature between 500 and 1100 °C. The composites which were prepared by hydrothermal reaction and blended spinning showed the outstanding photocatalytic activity at 900 °C and 1100 °C, respectively. And the photocatalytic activity of composites prepared by hydrothermal reaction was higher than that prepared by blended spinning, but reversibility of the composites showed a reverse trend. These results indicated that the effect of heat treatment temperature on the photocatalytic activity depended on the synergistic effect among the adsorptive property of CNFs, TiO 2 loading amount and anatase phase content in composites. Hence, combining the merits of hydrothermal reaction and blended spinning, a novel method for preparing CNFs@TiO 2 composites with high TiO 2 loading amount and strong interfacial interaction could be envisioned. [ABSTRACT FROM AUTHOR]

Abstract: Amber from northern Myanmar has been commercially exploited for millennia, and it also preserves the most diverse palaeobiota among the worlds'' seven major deposits of Cretaceous amber. Recent estimated ages vary from Albian to Cenomanian, based on palynology, an ammonoid, and Mesozoic insect taxa preserved within the amber. The burmite-bearing rock is sedimentary and consists mainly of rounded lithic clasts (0.03∼0.15mm in diameter), with minor fragments of quartz and feldspar. Among the lithic clasts are mostly volcanic rocks. Zircons separated from the amber matrix form two groups: Group-I zircons are overgrown and have variable CL patterns, experienced slight geological disturbances after they formed, and their Ion microprobe 206Pb/238U ages fall into a very narrow range of ∼102Ma–∼108Ma; Group-II zircons are typical magmatic ones with rhythmically flat zones, inferred to be derived from volcanic rock clasts, and yielded a concordia 206Pb/238U age of 98.79±0.62Ma. The dating on Group-I zircons is only for their interiors, thus hiding what age excursion might come from the overgrowth. Considering the nearshore marine environment and 1-m thickness of the burmite-bearing sediments, and the syn- and post-eruption deposition of volcanic clasts, the age of 98.79±0.62Ma therefore can be used as a maximum limit for the burmite (either at or after), establishing an earliest Cenomanian age for the fossilized inclusions. The age also indicates that volcanic eruption occurred at 98.79±0.62Ma in the vicinity of the Hukawng Valley. [Copyright &y& Elsevier]

Abstract: A subgroup is said to be an -subgroup of a finite group if for all . For every prime dividing the order of , let be a Sylow -subgroup of and a subgroup of with . We investigate the structure of under the assumption that each subgroup of with is an -subgroup of . Some earlier results are generalized. Some results about formation are obtained. [Copyright &y& Elsevier]

Abstract: Let be a complete set of Sylow subgroups of a finite group G, that is, for each prime p dividing the order of G, contains one and only one Sylow p-subgroup of G. A subgroup H of G is said to be -permutable in G if H permutes with every member of . In this paper we characterize p-nilpotency of finite groups G with assumption that some maximal subgroups or some 2-maximal subgroups of Sylow subgroups of G are -permutable. Some recent results are extended. [Copyright &y& Elsevier]

A subgroup S of a group G is called a p -sylowizer of a p -subgroup R in G if S is maximal in G with respect to having R as its Sylow p -subgroup. In this paper, we investigate the structure of the group G in which the sylowizers of each non-trivial primary subgroups in G are conjugate and give the non-solvable chief factors of G. [ABSTRACT FROM AUTHOR]

In this paper, we prove that if m ( G ) = 2 , then M ( G ) = 0 and solve two problems raised by Araújo et al. in [1] , where the notations m ( G ) and M ( G ) are introduced in [1] . [ABSTRACT FROM AUTHOR]

Abstract The classification of all block-transitive 2 − (v , k , 1) designs has been known as a long-standing and still open problem. This work is a contribution to the general program to classify the pairs (D , G) in which D is a 2 − (v , k , 1) design and G act as a point-primitive block-transitive automorphism group of D with a Suzuki group Sz (q) socle. We determine the point-stabilizer G α ∩ Sz (q) and the block-stabilizer G B ∩ Sz (q), and the parameter of D is given. [ABSTRACT FROM AUTHOR]

Thirty years ago, a six-person team classified the pairs ( D , G ) where D is a 2 − ( v , k , 1 ) design and G is a flag-transitive automorphism group of D , with the exception of those in which G is a one-dimensional affine group. Since then the effort has been to classify those D , designs which are block-transitive but not flag-transitive. This paper contributes to the program for determining the pairs 2 − ( v , k , 1 ) in which ( D , G ) has a block-transitive group G of automorphisms. It is clear that if one wishes to study the structure of a finite group acting on a D design then describing the socle is an important first step. Here we prove that if G is a block-transitive group of automorphisms of 2 − ( v , k , 1 ) which has D as its socle then T is also transitive on the blocks of T = 2 F 4 ( q ) . [ABSTRACT FROM AUTHOR]

Fifteen jujube cultivars late in their maturation were analysed in the red stage for bioactive compounds; including total phenolics (bound/free), total flavonoids, total polysaccharides, ascorbic acid, total triterpenes, proanthocyanidins and cyclic adenosine monophosphate (cAMP). The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydracyl (DPPH ) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS + ) scavenging methods and the ferric reducing antioxidant power (FRAP) assay. The Order Performance by Similarity to Ideal Solution method (TOPSIS) was employed to evaluate the nutrition of different jujube cultivars based on their bioactive compounds. The results indicated that the contents of bioactive compounds and antioxidant capacities vary between different jujube cultivars. Correlation analysis revealed that ascorbic acid, polyphenols and proanthocyanidins were the 3 main components responsible for the antioxidant activity of jujubes. TOPSIS analysis indicated that Zyzyphus jujube cv. Nanjingyazao ranks the highest of the 15 jujube fruits with regards to nutritional value. [ABSTRACT FROM AUTHOR]

The mechanism and timing of crustal growth and differentiation on early Earth are debated. Evidence of crustal differentiation is detectable as deviations from Earth's assumed chondritic uniform reservoir (CHUR) as crust is extracted from the mantle leading to a melt-depleted reservoir. For the long-lived zircon Lu-Hf system, no incontrovertible evidence of significant mantle depletion >3.8 Ga exists. We conduct combined U-Pb and Lu-Hf isotopic analyses for the detrital zircon from the Caozhuang supracrustal sequence in North China. The zircon Hf isotopic compositions are broadly scattered along the CHUR evolution line. However, given the possibility of potential systematic biases in zircon petrogenesis and the unique tectonic setting of early Earth, we posit that magmatism controlled by the nascent forms of plate tectonics during the Eoarchean could have likely hidden the degree of ancient crust-mantle differentiation. The non-depleted zircon Hf isotopes observed in North China and globally during early Earth may in verity imply the existence of ubiquitous depleted mantle domains at that time. [ABSTRACT FROM AUTHOR]

To improve energy efficiency and electrical power output of H 2 -fueled micro-thermophotovoltaic, burning in combustors with varied porous media (PM) settings is experimentally and numerically studied. Effects of burner dimensions, PM settings and operating conditions on flow field, species distribution, combustion characteristics and heat transmission are investigated and analyzed. Results demonstrate that inserted PM strongly affects burning properties and combustor thermal performance, which is enhanced in larger size combustors. The combination of partially inserted PM with inlet-step is conducive to flame anchoring, improving the efficiency at higher flow rate in small combustor because of the high surface values of Nusselt number and heat flux. The fully inserted PM is beneficial to the heat transfer in chamber at lower flow rate and achieves the highest radiation power of large scale burner. The limit of flow rate is dramatically broadened with the augment of burner scale, such as m r = 2.65 × 10−5 kg/s to m r = 4.64 × 10−5kg/s, and the highest electrical power of micro-thermophotovoltaic system with burner 9D and InGaAsSb cells reaches to 2.81 W. [ABSTRACT FROM AUTHOR]

Micro-thermophotovoltaic is facing challenge caused by small size, large area-volume proportion and heat loss ratio, reducing the burning stability and output power. So, the dual-inlet combustors with exit-step and porous medium are proposed for micro-thermophotovoltaic system. Effects of equivalence ratio, exit-step and porous medium setting on combustion characteristic and thermal performance are conducted and analyzed. Results demonstrate that 1% air in the second-inlet is conducive to releasing heat of combustion and optimizing wall temperature distribution, where the total equivalence ratio of H 2 /air keeps 1.0. Furthermore, the exit-step with applicable length and channel height can generate heat recirculation and enhance working performance of micro-combustor, while the employment of porous medium can further enhance heat transmission of gas-wall and boost the radiation temperature T w. Combustor CP13 with porosity ε = 0.85 obtains the highest average T w of 1273.9 K at m f = 3.376 × 10-5 kg/s. With the increase of m f , system efficiency of the combustor with porous medium is increased, while that with exit-step reaches the maximum at m f = 4.501 × 10-5 kg/s. The highest output electrical power and efficiency are appeared in combustor CP15 with ε = 0.95 at m f = 5.626 × 10-5 kg/s, that is, 4.2 W and 2.2%. [ABSTRACT FROM AUTHOR]

A fore-modified method was put forward and hybridized into hydrothermal process with acid, neutral and alkali circumstances. The activated fore-modified bio-hydrochars of feather and cornstalk (AFBF and AFBC) were manufactured. Some thinner carbon layers/smaller micro carbon spheres and much more hydroxyls functional groups were clearly observed in the acid and alkali fore-modified bio-hydrochars (AFBs). Batch experiments were taken to assess the AMOX removal abilities. By contrast, the AFB fore-modified by alkali, has got the most superior adsorbability of 92.87 mg/g. Particularly, the BET surface areas of AFBs increased by 155.46% and the adsorbance of AMOX increased as much as 42.92% than traditional bio-hydrochar. Zeta potentials were introduced to illustrate the interactions between adsorbents and adsorbates under different pH. In addition, the powerful chemical adsorptions processes were also demonstrated by kinetics tests. As a result, the fore- modified method was essential in improving the characters of Bio - hydrochars. [ABSTRACT FROM AUTHOR]

• Oxygen isotope alteration rate of continental crust retrieved from zircon record. • Oxygen isotope alteration rate of continental crust is controlled by weathering. • Weathering history is linked to major evolution events of the Earth system. Weathering plays a significant role in the Earth system through the exchange of material among the lithosphere, atmosphere, hydrosphere, and biosphere. Variation of continental weathering in deep-time, however, remains elusive. This work investigates continental weathering recorded by detrital zircon. Zircon can record the oxygen isotopic composition (δ 18 O) of its parent crust at the time of crystallization, the value of which principally reflects the time-integrated effect of crustal alteration. The Hf isotopes and U-Pb isotopes of zircon also help to constrain the alteration history between crust generation and zircon crystallization. A new algorithm is introduced to reconstruct the average δ 18 O alteration rate of continental crust (R δ 18O-CC) through time by solving a set of linear equations based on a large population of detrital zircons with varying temporal coverage across the history of crustal alteration. A nearly three-billion-year history of R δ 18O-CC from 3.2 Ga to 0.3 Ga can be reconstructed using more than 5,000 globally distributed detrital zircons with coupled U-Pb-Hf-O isotopic records. The reconstructed R δ 18O-CC shows an overall bell-shape long-term evolution centered at ∼2 Ga superposed with variations that are coupled with supercontinental assembly cycles. The long-term evolution of the reconstructed R δ 18O-CC seems to be correlated with solid-earth CO 2 degassing expected from the age distribution of deleted mantle and the supercontinental cycles. Thus, the R δ 18O-CC is interpreted to reflect weathering considering the control of solid-earth CO 2 degassing on the total weathering flux of continental crust. However, independent evidence on the solid-earth CO 2 degassing is unavailable, interpreting R δ 18O-CC as a weathering record requires further testing. Nevertheless, this work provides an example of how the time-integrated signal, with large noise-to-signal ratio, preserved in geological archives can be deconvolved using a large dataset. The result also demonstrates the great potential that weathering history may have in reconstructing the operation of the Earth system across deep-time. [ABSTRACT FROM AUTHOR]

Abstract: We report the petrography, mineralogy, trace element abundance geochemistry, and Pb–Pb geochronology of the lunar meteorite Northwest Africa (NWA) 4734 and make a comparison with the LaPaz Icefield (LAP) 02205/02224 low-Ti lunar basaltic meteorites. NWA 4734 is an unbrecciated low-Ti mare basalt composed mainly of subophitic-textured pyroxene (60vol%) and plagioclase (30%). Pyroxene, plagioclase, and olivine exhibit large compositional variations and intra-grain chemical zoning. Pyroxene and plagioclase in NWA 4734 have rare earth element (REE) concentrations and patterns similar to those of the LAPs. The crystallization age of NWA 4734, determined in situ in baddeleyite, is 3073±15Ma (2σ), nearly identical to that of the LAPs (3039±12Ma). NWA 4734 and the LAPs have similar textures, modal abundances, mineral chemistry, and crystallization ages, and are most likely source-crater paired on the Moon. One baddeleyite grain in LAP 02224 displays distinctively older and spatially variable ages, from 3349±62 to 3611±62Ma (2σ), similar to another baddeleyite grain (3109±29 to 3547±21Ma) reported by for the same meteorite. Raman spectra, cathodoluminescence, and stoichiometric studies of the baddeleyite suggest that the two older grains were not endogenic but were trapped by the parental magma. Equilibrium partition calculation shows that the parental melt from which the NWA 4734 plagioclase crystallized has much lower REE contents than its whole rock, indicating an open system during magma evolution. NWA 4734 could have originated from a parental melt with REE concentrations similar to that of the Apollo 12 olivine basalt. The magma likely assimilated a small amount (∼4wt%) of KREEP-rich material during its ascent through the lunar crust. [Copyright &y& Elsevier]

Abstract: Water-soluble polysaccharides isolated from the roots of Panax ginseng C. A. Meyer were completely fractionated into two neutral fractions (WGPN and WGPA-N) and six acidic fractions (WGPA-1-RG, WGPA-2-RG, WGPA-1-HG, WGPA-2-HG, WGPA-3-HG and WGPA-4-HG) by a combination of ethanol precipitation, ion-exchange and gel permeation chromatographies. The analytical results showed that WGPN was a starch-like glucan; WGPA-N was a mixture of starch-like glucan and arabinogalactan; WGPA-1-RG and WGPA-2-RG were composed of major neutral sugars and minor acidic sugars that belong to the type-I rhamnogalacturonan (RG-I)-rich pectins, while fractions WGPA-1-HG to WGPA-4-HG were mainly composed of galacturonic acid (GalA, 62.4–92.1%) and have been identified to be homogalacturonan (HG)-rich pectins with different degrees of methyl-esterification, ranging from 0% to 30%. High performance gel permeation chromatography (HPGPC) showed that the six acidic fractions were homogenous, with molecular weights approximately ranging from 3.5×103 to 1.1×105. Lymphocyte proliferation assays showed that both the neutral polysaccharides and acidic polysaccharides were potent B and T cell stimulators. [Copyright &y& Elsevier]

Abstract: Hydrocarbon migration pathways are the linkage between hydrocarbon source areas and accumulation sites. Modeling accurately the pathways of hydrocarbon migration is of important significance in determining the location of favorable petroleum exploration targets. In this paper, GIS-based modeling algorithms are presented for searching the pathways of secondary hydrocarbon migration by considering the geologic mechanisms. These algorithms are constructed on a raster digital elevation model (DEM) of the top boundary of a carrier bed, in which secondary migration occurred. On the DEM, a 3×3 pixel sized window is used for searching. The center of the search window is initially assumed at a point on the boundary of a hydrocarbon source area, from which the secondary hydrocarbon migration starts. The altitude values in the eight adjoining pixels enclosing the central pixel of the search window are compared, and the pixel with an altitude value not only larger than the central pixel but also the largest of the eight surrounding pixels is the next target pixel where the search window will move to. Each searched path will terminate at either a convex point, which indicates the existence of a trap for hydrocarbon accumulation, or a point on the boundary of the DEM, which suggests that the pathway of hydrocarbon migration extends outside the DEM. In addition, a concourse point of two paths is also considered as a termination point of either path. The algorithms were successfully applied in the modeling of the secondary migration pathways in the northern Songliao Basin, northeast China. The modeled results matched well with drilling data, suggesting the robustness of the algorithms. [Copyright &y& Elsevier]