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1.
Preparation and thermal stability of Pd<Subscript>40.5</Subscript>Ni<Subscript>40.5</Subscript>Si<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>19−<Emphasis Type="Italic">x</Emphasis></Subscript> bulk metallic glasses
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With the addition of Si to replace some P, Pd40.5Ni40.5Si
x
P19−x
(x=0, 2.5, 5, 9.5, 14, and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully
prepared by use of flux treatment and water quenching technology. With the increase of Si content, the glass forming ability
of Pd40.5Ni40.5Si
x
P19−x
increases first for low Si content and then decreases for high Si content (Si≥9.5at%). The Pd40.5Ni40.5Si
5
P14 glassy alloy possesses the largest supercooled liquid region ΔT of 119 K, the largest reduced glass transition temperature of 0.621, and the largest γ parameter of 0.460, indicating that this glassy alloy possesses very large glass forming ability and very high thermal stability. 相似文献
2.
Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were obser... 相似文献
3.
Based on density functional theory (DFT) of the first-principle for cathode materials of lithium ion battery, the electronic structures of (Li1?x Me x )FePO4 (Me=Na and Be, x=0–0.40) are calculated by plane wave pseudo-potential method using Cambridge serial total energy package (CASTEP) program. The calculated results show that Li-site doping can improve the electronic conductivity enormously. Doping with Na has a noticeable effect on improving its electrical conductivity. However, serious structural distortion will occur when its doping density is beyond 0.25. In view of this, the best density of doping Na is less than 0.25. Doping with Be has an inconspicuous effect on increasing its electrical conductivity and has good cyclical stability, but it cannot achieve as good results as when it is doped with Na. Therefore we cannot find a middle ground between the two proposals. Considering cost and environmental protection, it is ideal to choose Na. So this method gives a reasonable prediction to the improvement of electronic conductivity through Li-site doping in LiFePO4 material. 相似文献
4.
Letting a = 1 in a- Wythoff’s game introduced by Fraenkel yields Wythoff’s game which is a well-known 2-player impartial combinatorial game introduced by Wythoff in 1907. A method of solving n-player impartial games was presented by Krawec in 2012. In this paper, we employ Krawec’s function to analyze n > 2 players a-Wythoff’s game and obtain game values for all a 1. The results obtained cover n-player Wythoff’s game, a special case 1-Wythoff’s game. 相似文献
5.
TingTing Zhang YunZhi Song YuDong Liu XingQi Guo ChangXiang Zhu FuJiang Wen 《科学通报(英文版)》2008,53(23):3656-3665
The cDNA of AtPLDa (Arabidopsis thaliana Phospholipase Da) gene was introduced into P. tomentosa (Populus tomentosa) under the control of the Cauliflower mosaic virus 35S promoter. Southern and Northern blot analyses suggested that the AtPLDa gene has been transferred into the P. tomentosa genome. No obvious morphological or developmental difference was observed between the transgenic and wild-type (WT) plants. Drought and salt tolerance and gene expression of seedlings of several transgenic lines and WT plants (control) were studied. The results showed that the rhizogenesis rate and the average root-length of transgenic lines were significantly higher than WT plants after mannitol and NaCI treatment under the same growth conditions. Northern blot analysis indicated that the higher the PLDa expression in the transgenic plants, the more tolerant the transgenic plants are to drought and salt treatment. Meanwhile, another group of these transgenic lines and WT plants (control) were treated with PEG6000 and NaCI separately. The contents of chlorophylls and the activities of some anti- oxidant enzymes (superoxide dismutase, guaiacol peroxidase and catalase) as well as malondialdehyde and relative electrical conductivity were analyzed. Altogether, our results demonstrated that overexpression of the PLDa gene can enhance the drought and salt tolerance in transgenic P. tomentosa plants. 相似文献
6.
PengCheng Wei Su Chen XiuQing Zhang Ping Zhao YanMei Xiong WenLong Wang Jia Chen XueChen Wang 《科学通报(英文版)》2011,56(33):3531-3537
The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during
stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba epidermal strips. Expression of VfEXPA1 is regulated by darkness and submergence, and is not affected by light and abscisic acid (ABA). In situ hybridization showed that VfEXPA1 is expressed primarily in the guard cells. Overexpression of VfEXPA1 in transgenic tobacco accelerated light-induced stomatal opening, and increased both transpiration and photosynthetic rates
under favorable growth conditions. Our results indicate the guard cell-expressed expansin VfEXPA1 plays an important role in regulation of stomatal opening. 相似文献
7.
8.
Water-soluble β-cyclodextrin (β-CD)-modified carbon nanocrystals (CNCs) have been synthesized by the reaction of CNCs with mono(6-diethylenetriamino-6-deoxy)-β-CD (DETA-β-CD) and comprehensively characterized by 1H NMR, FT-IR, transmission electron microscopy (TEM) and UV-Vis. DETA-β-CD-modified CNCs (DETA-β-CD-CNCs) are luminescent, and the quantum yield is 8.41%. The photoinduced electron transfer (PET) process between DETA-β-CD-CNCs and (ferrocenylmethyl) trime-thylammonium iodide (Fc+) was investigated by means of fluorescence spectroscopy. 相似文献
9.
P chromosomes may carry a genetic system that inhibits the Ph gene in wheat. Abnormal chromosome synapsis in wheat-Agropyron cristatum addition line II-21-2 (additional 1·4 recombinant P chromosome) was observed in this study. The results of cytogenetics and Ph1 gene amplification showed that the Ph1 gene was normal and the average number of quadrivalents or hexavalents was determined to be 0.41 and 0.13, respectively, in pollen-mother cells of wheat-Agropyron cristatum addition line II-21-2. The analysis o... 相似文献
10.
The electronic properties and stabilities of five [Nb2W4O18OCH3]3− isomers have been investigated using a density functional theory method. The results show that the isomer with the methoxy
group occupying a bridging position between two tungsten atoms (two tungsten atoms in the plane that contains two niobium
atoms) in the [Nb2W4O18OCH3]3− framework is the most stable isomer in acetonitrile. The stability of the one-electron-reduced isomers changes little. The
most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4− framework. The M-Ob (M = Nb, W; b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy
group are longer than those in [Nb2W4O19]4−. The highest occupied molecular orbitals (HOMO) in [Nb2W4O19]4− mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,
and the bridging oxygen atoms on the axial surface. The lowest unoccupied molecular orbitals (LUMO) of [Nb2W4O19]4− are mainly concentrated on the tungsten atoms and antibonding oxygen atoms. Methoxy substitution modifies the electronic
properties of the [Nb2W4O18OCH3]3− isomers. The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms, which are distant from the surface
containing the methoxy group and four metal atoms. The LUMOs delocalize over the d-shells of the four metal atoms that are
close to the methoxy group, and the p-orbitals of oxygen. One-electron reduction occurred at the tungsten atoms, not the niobium
atoms. 相似文献
11.
An effective, catalytic method has been developed to remove TBS and THP groups from protected alcohols. TBS and THP ethers were selectively cleaved using a catalytic amount of NO+BF4– (5 mol%) in methanol at room temperature. 相似文献
12.
Highly diastereoselective addition of lithium enolate of γ-substituted α-diazoacetoacetate to chiral N-sulfinyl imines has been developed. The addition products were further subjected to photo-induced Wolff rearrangement or Rh(II)-catalyzed intramolecular N–H insertion to afford chiral 4,5-disubstituted 2-oxo and 3-oxo pyrrolidines, respectively. 相似文献
13.
Surface snow samples were collected during the 14th (1997/1998) and 24th (2007/2008) Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A. The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters (latitude, longitude, altitude and distance to the coast). The results reveal a strong positive correlation (R=0.945) between δ18O and mean annual temperature, with a gradient of 0.84‰°C –1, which is a little higher than that in Terre Adelie Land. Regression analyses also show that the δ18O of surface snow is strongly correlated with distance to the coast (R=0.942), latitude (R=0.942), and altitude (R=0.941). But no significant correlation was found between δ18O and longitude in study area. Altitude should be the most important factor influencing the δ18O distribution because of distinctive topography. The δ18O-altitude and T-altitude gradients along this transect are determined to be –1.1‰/100 m and 1.31°C/100 m, respectively. 相似文献
14.
Degenerate four-wave mixing measurements, using the 35 ps pulses at 532 nm, have been employed to investigate the third-order nonlinear optical parameters of two chromium tricarbonyl complexes η6-bonded to 3-amino-9-ethylcarbazole at either the NH2-substituted aryl ring (1) or the unsubstituted ring (2) and their precursor 3-amino-9-ethylcarbazole (AECz). The second-order hyperpolarizability y of the compounds 1 and 2 were found to be 42.9×10^-31 and 35.9×10^-31 esu, respectively, approximately one order of magnitude greater than AECz. The relation between the molecular structure and second-order hyperpolarizability of the compounds I and 2 was explored in detail based on the three-level model and the density functional theory (DFT) calculation. The theoretical results indicate that the spatial distribution of electron density has the profound role in the third-order nonlinear optical properties. 相似文献
15.
Here we reported the fatty-acids and their δ13C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ~540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ~2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C16. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ13C values (−39.99‰ to −32.36‰) of n-C12:0, n-C13:0, i-C14:0 and n-C14:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C18:2 and C18:1△9 have the same δ13C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lower δ13C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites. 相似文献
16.
Difference in the genomic compositions of prokaryotes is the basis of the diversity in their biological characters. However,
besides their flora- or strain-specific genes, those floras with closer relationship in the evolution also have conserved
“backbone sequences”, which reveal the marks of their origin and evolution, and these “backbone sequences” are just the basis
of their elementary living abilities and common biological properties. Shigella is very closely related to E. coli in the
origin and evolution, and may turn out to belong to the same genus. In this study, a microarray containing E. coli K-12 whole
genome and SG01 specific ORFs is used to investigate the genomic components of four Shigella strains. The results indicate
that 16%–22% K-12 ORFs sequences are not detected in the genome of Shigella strains while the genome of Shigella contains
at least 2800 conserved ORFs, which compose the common “backbone sequences”. Advanced analysis indicated that the “backbone
sequences” are the essential components in maintaining the normal physiological activities of intestinal bacteria. Furthermore,
only 20% SGO1-specific ORFs exist in other strains simultaneously, which demonstrate the great genome heterogeneity and the
genetic diversity among the strains.
the first two authours made equal contribution to this work. 相似文献
17.
Chengcheng Li Wenli Ji Jiayi Sun Qiaoli Li Jingxuan Yang Shuangyu Wei Yanlong Zhang 《武汉大学学报:自然科学英文版》2018,23(1):56-62
The influence of the foliage boron(B)-spaying concentration on the yield and fatty acid composition of tree peony (Paeonia ostii ‘Feng Dan’) was explored in the experiment of 2014-2015. In this research, a statistically significant correlation was found between the mass concentration of foliage boron- spraying and tree peony seed yield. Maximum yield increment of tree peony seeds was obtained when the boron-spraying concentration was 4 g/L. The composition of fatty acid was analyzed by gas chromatography-mass spectrometry (GC-MS), and the main components of the fatty acid composition were quantified by internal standard method. The increase in the oil extraction rate after foliage boron-spraying nutrition of different concentration was significant and ranged between 0.04% and 11.43%. Seed oil production and oil extraction rate were also increased due to the increase of seed yields. Furthermore, foliage boron-spraying had a significant effect on the content of linolenic acid and linoleic acid in seed oil. 相似文献
18.
Hui Zhou CongQiang Liu Qian Jiang Wei Jiang YanLong Zhao WenCi Ding Hui Yan 《科学通报(英文版)》2010,55(36):4162-4167
Dissolved inorganic carbon (DIC) is a primary constituent of the aquatic geochemistry of terrestrial ecosystems. Changes in
DIC concentration and its isotopic composition are closely associated with environmental changes in the drainage basin. Thus,
a better understanding of DIC may lead to improved characterization of environmental changes. Corbicula fluminea (Müller 1774), a bivalve native to southeast Asia and a dominant invasive species in many aquatic environments around the
world, has the potential to record DIC information, particularly because of its sequential skeletal deposition. Analysis of
the stable carbon isotope composition (δ
13C) of the shell and the aquatic DIC in the Xijiang River drainage basins in southern and western China allowed us to determine
that changes in δ
13C in the skeleton significantly correlated with those of DIC (P < 0.01, r = 0.63). These results indicate that the isotopic signature of the shell reflects that δ
13C of the DIC in ambient water. The temporal resolution was at the seasonal scale. Metabolic effect does not change the co-variation,
even though it makes the shell δ
13C 1.4‰ lower statistically than that of DIC. δ
13C of DIC in creeks of some watershed areas may experience large temporal changes characterization of these changes requires
high sampling resolution of the shell. This problem makes the clams in these areas less preferable for reconstruction of environmental
changes. The present findings provide the basis for recovering paleoenvironmental changes and carbon cycles in a watershed
through analysis of fossil shells of C. fluminea, which are common in some lacustrine and/or riverine sediment sequences. 相似文献