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1.
The Taylor dispersion method was used to measure diffusion coefficients of three-component liquid systems. An improved constrained nonlinear least-square method was used to evaluate the ternary diffusion coefficients directly by fitting the mathematical solutions of the dispersion equation to eluted solute peaks detected using a differential refractometer. Diffusion coefficients of the three-component system of acetone-benzene-CCl4, determined at 25℃, were used to test the procedure. The measured diffusion coefficients were compared with values obtained by optical interferometry and the diaphragm cell method. Ternary diffusion coefficients are also determinated for solutions of 1-hexanol-hexane-toluene and 1-propanol- water-ethylene glycol at 25℃, with an accuracy of approximately 0.05 m^2·s^- 1.  相似文献   

2.
The Kunyang rift lying on the western margin of the Yangtze platform is a rare Precambrian Fe-Cu mineralization zone. Wuding- Lufeng basin that is an important part of the zone is located on the west edge in the middle of the rift. The most important ore-hosting rocks are Mesoproterozoic dolomite rocks in the basin controlled by a ring fracture system, which is a fundamental structure of the basin. Plenty of silicate minerals and acicular apatite, feldspar phenocrysts and small vesicular, flown line and flown plane structures, melt inclusion and high temperature fluid inclusion found in most ore-hosting dolomites suggest that this kind of rocks could not be sedimentary dolomite, marble or hydrothermal carbonate rocks. The Zr/Hf and Nb/Ta values of the rocks are identical with those of associated mantle-derived rocks, and vary widely. For the monomineral dolomite, δ^18OSMOW‰=+5.99 to +18.4 and δ^13CPDB‰ = -3.01 to +0.94, which fall within the range for all carbonatitic volcanic rocks of the world. As for the accessory minerals, the values of δ^18OSMOW‰ of magnetite (=+3.47 to +5.99‰) are close to that of the mantle (〈5.7%), and the δ^34S‰ values of sulfides (-5.09 to +5.78, averaging +1.50) are close to that of meteorite. For all the ore-bearing dolomite rocks, εNd = +0.19 to +2.27, and the calculated Isr=0.699143, while for the associated mantle-derived rocks, εnd = +3.18 to +3.72. All the data suggest that the mineral assemblage is not only igneous but also of metasomatic mantle origin. And the presence of acicular apatite indicates that the rocks were formed by magma rapidly cooling. And the phenocryst texture and vesicular, flown and ropy and pyroclastic structures suggest that the igneous rocks were extrusive. Therefore, the ore-bearing dolomite rocks are carbonatitic volcanic rocks. This conclusion implies that most iron and copper ore deposits hosted in the dolomite rocks should be of the carbonatite type.  相似文献   

3.
A polymerase chain reaction (PCR)-based strategy was developed to rapidly obtain the gene encoding for an industrially important enzyme, glutaryl-7-aminocephalosporanic acid (GL-7-ACA) acylase.Different soil samples were cultured with a Pseudomonas selective medium to enrich specific microorganisms, and then the genomic DNA was extracted to serve as PCR templates. PCR primers for GL-7-ACA acylase gene amplification were designed on the basis of bioinformatics searches and analyses.The method was used to successfully amplify three GL-7-ACA acylase genes from different soil samples.The GL-7-ACA acylase genes were then cloned and overexpressed in Escherichia coil with a relatively high level of 266 unit · L^-1.  相似文献   

4.
Multiphase computational fluid dynamics (CFD) has become an alternative method to experimental investigation for predicting the fluid dynamics in gas-solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas- and solidphase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidization of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i.e., fine alumina powder (dp= 60 μm and pp = 1500 kg/m^3) and sand (dp = 610 μm and pp = 2500 kg/m^3), are numerically simulated in a rectangular duct of 0.2 m (long) × 0.2 m (wide)× 0.5 m (high) size. The results show good agreement with the classic theory of Geldart.  相似文献   

5.
We conducted an oceanographic census in 1959, 2002, and 2005 to evaluate changes in the temporo-spatial distribution and abundance of Lucifer intermedius and L. hanseni in the Changjiang estuary. In general, the abundance and frequency of occurrence (OF) for these two species were highest during the summer. We measured a significant change in the abundance and OF between years. The abundance and OF of L. intermedius increased from 3.7 individuals m−3 and 66.67%, respectively, in 1959, to 8.93 individuals m−3 and 85.19%, in 2002. In 1959, L. hanseni was only found during the summer (abundance: 0.01 individuals m−3, OF: 3.70%). However, in 2002, this species was collected during all seasons except the winter. Furthermore, abundance (0.47 individuals m−3) and OF (25.93%) were higher in 2002 than in 1959. Further increases in abundance and OF were measured during cruises during the spring of 2005. We hypothesize that global warming is responsible for the increase in abundance of L. intermedius and L. hanseni and the northward expansion of L. hanseni in the Changjiang estuary. Given our results, monitoring of both species may be useful to evaluate the effects of climate change.  相似文献   

6.
A laboratory study on the liquid–liquid extraction system has been carried out for the removal and recovery of methyl red from aqueous solutions using xylene as an extractant. The concentration of methyl red has been studied in the range of 1.72 × 10−4 to 1.72 × 10−3 mol L−1. The efficiency of dye extraction increased with increasing time of extraction. Distribution ratio is reasonably high (D = 49) even in the presence of inorganic salts. Extracted dye in the organic phase has been stripped into sodium hydroxide solution. The organic solvent is reused for reextraction of the dye from aqueous solution. The efficiency of reused organic solvent was maintained up to 10 runs. Loading capacity of dye has been found to be 14.32 mg. Under optimized conditions, real textile wastewater has been studied and the results are satisfactory.  相似文献   

7.
Lithium iron phosphate coated with carbon (LiFePO4/C) was synthesized by improved solid-state reaction using comparatively lower temperature and fewer sintering time. The carbon came from citric acid, which acted as a new carbon source. It was characterized by thermogravimetry and differential thermal analysis (TG/DTA), X ray diffractometer (XRD), Element Analysis (EA) and Scanning electron microscope (SEM). We also studied the electrochemical properties of the material. The first discharge capacity of the LiFePO4/C is 121 mAh·g−1 at 10 mA·g−1, at room temperature. When the current density increased to 100 mA·g−1, the first discharge capacity decreased to 110 mAh·g−1 and retained 95% of the initial capacity after 100 cycles. The LiFePO4/C obtained shows a good electrochemical capacity and cycle ability at a large current density. Foundation item: Supported by the National Natural Science Foundation of China (20071026) Biography: ZHOU Xin-wen (1980-), male, Master, research direction: inorganic material chemistry.  相似文献   

8.
We consider the Poisson integral u = P*μ on the half-space R+^N+1 ( N 〉 1 ) (or on the unit ball of the complex plane) of some singular measureμ. If μ is an s-measure (0 〈 s 〈 N), then some sharp estimates of the integration of the harmonic function u near the boundary are given. In particular, we show that fpr p〉1,∫R^Nu^p(x,y)dx- y^-τ (y〉0,τ =(N-s)(p-1) ) (Given for p〉1, RN f 〉 0 and g 〉 0, " f-g " will mean that there exist constants C1 and C2, such that C1f ≤ g ≤ CEf ).  相似文献   

9.
A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N41°18.979′, E119°14.318′), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Protagrypnini. Some primitive characters of the new genus and new species shed light on the ages between the Jiulongshan Formation in Inner Mongolia and the Yixian Formation in the western Liaoning Province of China. The habitat of the new species is briefly discussed.  相似文献   

10.
The ATP in roots and xylem sap of two woody plant species, Platycladus orientalis and Acacia auriculiformis, subjected to rapid and slow soil drying has been determined employing firefly luciferase ATP assay method (sensitivity is at 10-12 mol ATP L-1). The ATP levels in the two species were 1.6 nmol·gDW-1 and 0.6 nmol·gDW-1 in roots, and 5.6 μmol·m-3 and 8 μmol ·m-3 in xylem sap, respectively. When plants of P. orientalis and A. auriculiformis were subjected to rapid soil drying, respectively, as soil water content (SWC) decreased from the normal level ( 0. 25 g ·gDW-1) to 0. 02 and 0. 06 g ·gDW-1, separately, plant water potential ( ) dropped to -4 and -3.2 MPa, differently, the ATP in roots decreased 99.7% and 42%, respectively . When the rapidly dried soil was watered for up to 6 d, SWC and were found to recover to their normal levels, but ATP content in roots of P. orientalis and A. auriculiformis recovered by 10% and 23%, respectively. When plants of P. orientalis and A. auriculiformis were subjected to slow soil drying, respectively, as SWC was found to decrease from the normal level to 0.1 and 0.13 g·gDW-1, separately, dropped to - 2.5 and - 2 MPa, differently, the ATP content in roots decreased 98% and 38%, respectively. When the slowly dried soil was watered for up to 8 d, ATP levels in roots of P. orientalis and A, auriculiformis recovered by 30% and 24%, respectively. However, ATP concentrations in xylem sap were not directly influenced by either SWC or . The plot dots of xylem sap ATP concentration versus root ATP content were found to be distributed diagonally. It is concluded that ATP in roots is more sensitive in response to SWC changes than that to and root-sourced ATP is a source of that in xylem sap. When plants are subjected to slow soil drying, the ATP levels in both root and xylem sap are higher than that to rapid soil drying.  相似文献   

11.
为研究不同生长基质对降香黄檀(Dalbergia odoriera)叶片表型可塑性(Phenotypic plasticity)的影响,为降香黄檀在石漠化地区的栽培提供依据,以全壤土和全石砾生长基质栽培下的降香黄檀幼苗为研究对象,采用石蜡切片法对叶片的形态解剖参数可塑性进行研究.结果表明:雨季(6月)取样的降香黄檀叶片...  相似文献   

12.
Boneh and Durfee have developed a cryptanalytic algorithm on low private key RSA. The algorithm is based on lattice basis reduction and breaks RSA with private key d<N0.292. Later on, an improved version by Blömer and May enhanced the efficiency, while reaching approximately this same upper bound. Unfortunately, in both the algorithms, there is a critical error in theoretical analysis, leading to the overestimated upper bound N0.292. In this paper we present a more precise analytical model, with which the theoretical upper bound on d is modified to approximately d<N0.277 for ordinary RSA systems with a 1024-bit public key (N,e).  相似文献   

13.
0Introduction LetGbeafinitegroupoforder|G|=g,andletR(G)denotethecharacterringofG,whichisgeneratedbyalltheirreduciblecomplexcharactersofG.LetZbetherationalintegerringandNthesetofnatural numbers,andletZ[ω]betheintegralextensiongeneratedbyaprimitiveg throotωofunity.SupposethatSisasubringof thealgebraicnumberfieldsuchthatZ[ω]S.πisasetofra tionalprimenumbersdefinedasfollowsπ={p|pisarationalprimenumbersuchthatp-1S}.Definition1WecallthataconjugacyclassCofthefinite groupGisaπregularconju…  相似文献   

14.
Gallium, Ge, V, and U are the associated valuable elements in coal. From the 1950s to the 1970s, some researchers in the departments of coal industry and mineral resources of China investigated these elements in coal during geological explorations. The enrichment mechanism and the environmental influence of trace elements in coal have been deeply studied in recent twenty years. With respect to the ore-forming theories and practical utilizations of metals in coal, germanium was furthest studi…  相似文献   

15.
The results of research on the effects of anions on the biosorption of microelement cations by the edible marine macroalga Enteromorpha prolifera in singleand multi-metal systems are discussed in this paper. It was shown that the maximum biosorption capacity (qmax) in a single-metal system of Co(II) ions decreased in the following sequence: Cl- (46.0 mg g-1) > SO42- (42.8 mg g-1) > NO3- (41.9 mg g-1). In multi-metal systems, in which the ratios of Cl-, NO3-, and SO42- were 0:0:4, 1:1:2, 3:0:1, and 4:0:0, there were clear differences among the biosorption capacities. In all the examined systems (other than the 0:0:4 system), inhibition of the binding of microelement cations by the macroalga was observed. In all the systems, the highest value of qmax was obtained for Cu(II) cations; the value ranged from 31.9 mg g-1 in 0:0:4 (SO42- only) to 18.2 mg g-1 in 4:0:0 (Cl-only).  相似文献   

16.
为研究不同因素对药食两用植物赤苍藤(Erythropalum scandens Bl.)种子萌发和幼苗生长的影响,本研究以当年采收的赤苍藤种子为材料,探讨浸种时间(0 d、1 d、2 d、3 d、4 d、5 d)、基质含水量(70%、50%、30%)、播种深度(0 cm、1 cm、3 cm、5 cm)、光照条件(全黑、自然光)、基质(沙土、肥土、黄土、混合土)、赤霉素浸种处理及破壳处理(全破、少破、不破)下赤苍藤种子的发芽率及幼苗特性,为其规模化发展提供理论参考。结果表明,浸种时间、基质含水量、播种深度、赤霉素处理均对发芽率有极显著影响(P<0.01),基质和破壳处理对发芽率有显著影响(P<0.05),浸种5 d、50%和30%的基质含水量、播种深度1 cm、混合土基质、50 mg·L-1赤霉素浸种12 h以及全破处理的发芽率在各对比的处理中均最高。浸种时间和基质含水量对幼苗叶长和枝高均有显著影响(P<0.05),其他处理对幼苗生长无显著影响。综上可知,赤苍藤种子育苗时,可先浸种5 d或用50 mg·L-1赤霉素浸种12 h...  相似文献   

17.
We study the spaces Hp, Sp, Kp, ∑p and ,p of martingales with measure du=ψdυ,where ψ is a function with Clifford algebra values and satisfies bp+-condition. We proved they are equivalent and isomorphic to the corresponding spaces of martingales with real measure dυ, respectively(1≤p<∞). In the end,we give a martingale f such that f=(fn) ∞∈1K∞ but f=(E(ψ| n)fn)n≥ ∈1K∞.  相似文献   

18.
PEG-g-poly(aspartamide-co-N,N-dimethylethylenediamino aspartamide) (PEG-DMEDA-PASP) was synthesized by two-step ring-opening reactions of polysuccinimide (PSI) with α-methoxy-ω-amino-poly(ethylene glycol) and N,N-dimethylethylenediamine. The polymer structure was confirmed by 1H NMR and FT-IR. The resultant PEG-DMEDA-PASP with ammonium glycyrrhizinate (AMG) could form polymeric micelles in aqueous solution. The results of transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements revealed that these polymeric micelles were spherical particles with a narrow diameter distribution and that their average diameter was ca. 70 nm. These polymeric micelles had high-loading capacity (58%) and encapsulation efficiency (70%) for AMG. The results of in vitro release experiments showed that these polymeric micelles possessed sustained-release effects, with a release rate of 25% within 3 h and 90% within 24 h.  相似文献   

19.
We examined the effect of excessive Internet use on the time–frequency characteristic of the electroencephalogram by wavelet transformed and non-negative matrix factorization (NMF). The event-related potentials (ERP) of normal subjects and excessive Internet users were acquired using the oddball paradigm experiment. We applied the wavelet transformed and event-related spectral perturbation to ERP in order to extract the time–frequency values. The F-test statistics of time–frequency values were then decomposed into two components by NMF. Excessive Internet use resulted in a significant decrease in the P300 amplitudes (P < 0.05) and a significant increase in the P300 latency (P < 0.05) in all electrodes. The major effect of excessive Internet use on gamma oscillation occurred at 300 ms after stimuli at 40–50 Hz on the parietal central region. Thus, these data suggest that excessive Internet use affects information coding and integration in the brain.  相似文献   

20.
对模拟空间微重力条件下大鼠T细胞发育受阻的神经免疫调节机理进行初步探究.采用流式细胞检测技术测定模拟微重力大鼠胸腺中不同发育阶段T淋巴细胞的数量变化,用ELISA法测定胸腺组织中去甲肾上腺素(NE)和内源性糖皮质激素(GC)的含量.结果表明模拟微重力模型大鼠出现明显胸腺萎缩(p<0.05),CD3+CD4+CD8-和CD3+CD4-CD8+T细胞数量明显减少(p<0.05);模拟微重力大鼠胸腺中NE和GC含量有升高的趋势.模拟微重力大鼠胸腺中发生了从双阳性T细胞向单阳性T细胞的发育阻滞,这种异常可能与神经内分泌免疫调控相关.  相似文献   

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