Chinese Science Bulletin

Advanced Search

Subscribe		Email Alert


	Home \| About Journal \| Editorial Board \| Instruction \| Subscription \| Advertisement \| Contacts Us \| Chinese Version

Editor office board

Quick Search

Advanced Search

More>>

Office

　· Online Submission

　· Manuscript Tracking

　· Peer Review

　· Editor Work

　· Office Work

　· Editor-in-chief

Journal

　· Forthcoming Articles

　· Current Issue

　· Next Issue

　· Hot Papers

　· Archive

　· Advanced Search

　· Archive By Volume

　· Archive By Subject

　· Most Read Articles

　· Most Downloaded

　· Email Alert

Download

　· Instruction

　· Template

　· Copyright Agreement

Other journals

· Chines science bulletin

· Science in China Series
A-Mathematics

· Science in China Series
B-Chemistry

· Science in China Series
C-Life Sciences

· Science in China Series
D-earth Sciences

· Science in China Series
E-Technological Sciences

· Science in China Series
F-Information Sciences

· Science in China Series
G-Physics and Astronomy

Links

　· CNKI

　· Wanfan Data

　· More...

　Total visitors:
Visitors of today:
　Now online:

	Latest Printed Issue 2008 Vol.53 Number 10 May 30, 2008 Content is this issue
	REVIEW
	ARTICLES
	BRIEF COMMUNICATION

REVIEW

	1457	WU DongDong and ZHANG YaPing
		Positive Darwinian selection in human population: A review
		This paper reviews a large number of genes under positive Darwinian selection in modern human populations, such as brain development genes, immunity genes, reproductive related genes, perception receptors. The research on the evolutionary property of these genes will provide important insight into human evolution and disease mechanisms. With the increase of population genetics and comparative genomics data, more and more evidences indicate that positive Darwinian selection plays an indispensable role in the origin and evolution of human beings. This paper will also summarize the methods to detect positive selection, analyze the interference factors faced and make suggestions for further research on positive selection.
		2008 Vol. 53 (10): 1457-1467 [Abstract ] ( 81 ) [HTML 0KB] [PDF 374KB ]( 49 )

ARTICLES

	1468	CHEN Zhan, XU JunFeng, HUANG Wei, CHEN WeiZhong and MIAO GuoQing
		An experiment on multibubble sonoluminescence spectra in sodium chloride solution
		We investigated experimentally the spectra of MBSL in sodium chloride water solution with krypton as dissolved gas. We observed and compared the spectra of hydroxyl ion at 310 nm and that of sodium atom at 589 nm. It has been found that under the same experimental condition, the intensity of sodium atom spectra is obviously higher than that of the hydroxyl ion spectra, and is more sensitive to the experimental condition. The krypton content, the concentration of sodium chloride solution, and the driving sound pressure obviously affect the spectra intensity in certain range.
		2008 Vol. 53 (10): 1468-1472 [Abstract ] ( 55 ) [HTML 0KB] [PDF 539KB ]( 41 )

	1473	YUAN YiZhong, SUN ZhenRong and WANG ZuGeng
		Structural dependences of the η⁶ complexes of 3–amino–9-ethylcarbazole with chromium tricarbonyl fragment on third-order optical nonlinearities
		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 γ 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 1 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.
		2008 Vol. 53 (10): 1473-1478 [Abstract ] ( 54 ) [HTML 0KB] [PDF 574KB ]( 23 )

	1479	CUI ChenZhou, SUN HuaPing, ZHAO YongHeng, LUO Yu and QI DaZhi
		SkyMouse: A smart interface for astronomical on-line resources and services
		With the development of network and the World Wide Web (WWW), the Internet has been growing and changing dramatically. More and more on-line database systems and different kinds of services are available for astronomy research. How to help users find their way through the jungle of information services becomes an important challenge. Although astronomers have been aware of the importance of interoperability and introduced the concept of Virtual Observatory as a uniform environment for future astronomical on-line resources and services, transparent access to heterogeneous on-line information is still difficult. SkyMouse is a lightweight interface for distributed astronomical on-line resources and services, which is designed and developed by us, i.e., Chinese Virtual Observatory project. Taking advantage of screen word-capturing technology, different kinds of information systems can be queried through simple mouse actions, and results are returned in a uniform web page. SkyMouse is an easy to use application, aiming to show basic information or to create a comprehensive overview of a specific astronomical object. In this paper current status of on-line resources and services access is reviewed; system architecture, features and functions of SkyMouse are described; challenges for intelligent interface for on-line astronomical resources and services are discussed.
		2008 Vol. 53 (10): 1479-1483 [Abstract ] ( 45 ) [HTML 0KB] [PDF 633KB ]( 19 )

	1484	GAO Shan, LIANG XueZheng, CHENG WenPing, WANG WenJuan and YANG JianGuo
		An efficient heterogeneous procedure for the catalytic acetalization and ketalization at room temperature under solvent-free condition
		A novel carbon-based strong acid catalyst, methylnaphthalenesulfonic acid - formaldehyde condensate, has been synthesized successfully. The catalytic activity for acetalization and ketalization at room tem-perature under solvent-free condition was investigated. The results showed that the novel catalyst was very efficient for the reaction. Also the novel heterogeneous catalyst owned the advantages of high activity, wide applicability, strikingly simple work-up procedure, non-pollution, stability and reusability, which made the catalyst hold great potential for the “green process”.
		2008 Vol. 53 (10): 1484-1488 [Abstract ] ( 60 ) [HTML 0KB] [PDF 238KB ]( 25 )

	1489	LUuml, LingLing, WANG XiaoFang, WANG YongCheng and DAI GuoLiang
		A theoretical study of the proton transfer process in the spin-forbidden reaction ¹HNO(¹A′) + OH^-→³NO^-(³Σ^-) + H₂O
		The spin-forbidden reaction ¹HNO(¹A′)+OH^-→³NO^-(³Σ^-)+H₂O has been extensively explored using various CASSCF active spaces with MP2 corrections in several basis sets. Natural bond orbital (NBO) analysis, together with the NBO energetic (deletion) analysis, indicates that the two isomers have nearly equal total energy and could compete with each other in the title reaction. More significantly, the singlet/triplet surface crossing regions have been examined and the spin-orbit coupling (SOC) and energetics have been computed. The computational results indicate that the SOC is very large at the crossing point T₁/S₀ trans (ca. 40.9 cm^-1). Moreover, the T₁/S₀ trans has a low energy of 10.67 kcal/mol relative to that of trans-S₀. Therefore, the surface crossing to the triplet state seems much more efficient at the T₁/S₀ trans region along the minimum energy path (MEP), However, The values of single (P₁^ISC) and double (P₂^ISC) passes estimated at T₁/S₀ trans show that the ISC occurs with a little probability.
		2008 Vol. 53 (10): 1489-1496 [Abstract ] ( 60 ) [HTML 0KB] [PDF 837KB ]( 23 )

	1497	ZHAO Chao, HUANG YingPing, FANG YanFen, JIANG LiRong, LIU LiMing and King Tong Lau
		Visible light-induced degradation of organic pollutants using Fe(II) supported on silica gel as an effective catalyst
		Silica gel-supported Fe(II) (SiOFe) was prepared and used for heterogeneous degradation of sulforhodamine B (SRB) and 2,4-dichlorophenol (DCP) under visible irradiation (λ > 420 nm) as an effective catalyst. UV-visible spectra, and infrared Spectrophotometry (IR), fluorescence, total organic carbon (TOC) and electron spin resonance (ESR) measurements were employed to analyze the photoreaction products. The results showed that SRB could be efficiently degraded by SiOFe/H₂O₂ system under visible irradiation with 100% decolorization and 72.3% TOC removal after 180 min illumination. The results of ESR and fluorescence measurements indicated that the oxidative process was predominated mainly by the hydroxyl radical (·OH) generated in the system.
		2008 Vol. 53 (10): 1497-1502 [Abstract ] ( 54 ) [HTML 0KB] [PDF 598KB ]( 24 )

	1503	CHEN LiQin, GUO YiFei, YANG LiMin and WANG QiuQuan
		Synergistic defensive mechanism of phytochelatins and antioxidative enzymes in Brassica chinensis L. against Cd stress
		Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins (PCs), and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.
		2008 Vol. 53 (10): 1503-1511 [Abstract ] ( 54 ) [HTML 0KB] [PDF 597KB ]( 22 )

	1512	WANG Peng, DING YeZhang, LU QiongXian, GUO WangZhen and ZHANG TianZhen
		Development of Gossypium barbadense chromosome segment substitution lines in the genetic standard line TM-1 of Gossypium hirsutum
		Chromosome segment substitution lines (CSSL) consist of a battery of near-isogenic lines that have been developed and cover the entire genome of some crops. With the exception of one homozygous chromosome segment transferred from a donor parent, the remaining genome of each CSSL line is the same as the recipient parent. It is an ideal material for genome research and particularly QTL mapping. In the present study, we first developed one set of CSSL lines using G. hirsutum acc. TM-1 (the genetic standard), as the recipient parent and G. barbadense cv. Hai7124 as the donor parent using molecular assisted-selection in BC₅S_1-3 generations. The CSSL consisted of 330 different lines, in which 1―4 different lines had the same or overlapping substituted segments. The genetic length of the substituted segments covered 5271.9 cM with an average segment distance of 10.9 cM, 1.5 times the total genetic length of Upland cotton (3514.6 cM). The substituted segments of each line varied in length, ranging from 3.5 cM for the shortest segment to 23.2 cM in the longest segment. Our CSSL have not yet to cover the entire tetraploid cotton genome, due to the absence of some donor parent interval segments.
		2008 Vol. 53 (10): 1512-1517 [Abstract ] ( 49 ) [HTML 0KB] [PDF 986KB ]( 18 )

	1518	HAO ChenYang, DONG YuChen, WANG LanFen, YOU GuangXia, ZHANG HongNa, GE HongMei, JIA Ji-Zeng and ZHANG XueYong
		Genetic diversity and construction of core collection in Chinese wheat genetic resources
		Genetic diversity among 5029 accessions representing a proposed Chinese wheat core collection was analyzed using 78 pairs of fluorescent microsatellite (SSR) primers mapped to 21 chromosomes. A stepwise hierarchical sampling strategy with priority based on 4×105 SSR data-points was used to construct a core collection from the 23090 initial collections. The core collection consisted of 1160 accessions, including 762 landraces, 348 modern varieties and 50 introduced varieties. The core ac-counts for 23.1% of the 5029 candidate core accessions and 5% of the 23090 initial collections, but retains 94.9% of alleles from the candidate collections and captures 91.5% of the genetic variation in the initial collections. These data indicate that it is possible to maintain genetic diversity in a core col-lection while retaining fewer accessions than the accepted standard, i.e., 10% of the initial collections captured more than 70% of their genetic diversity. Estimated genetic representation of the core con-structed by preferred sampling (91.5%) is much higher than that by random sampling (79.8%). Both mean genetic richness and genetic diversity indices of the landraces were higher than those of the modern varieties in the core. Structure and principal coordinate analysis revealed that the landraces and the modern varieties were two relatively independent subpopulations. Strong genetic differentia-tion associated with ecological environments has occurred in the landraces, but was relatively weak in the modern cultivars. In addition, a mini-core collection was constructed, which consisted of 231 ac-cessions with an estimated 70% representation of the genetic variation from the initial collections. The mini-core has been distributed to various research and breeding institutes for detailed phenotyping and breeding of genetic introgression lines.
		2008 Vol. 53 (10): 1518-1526 [Abstract ] ( 52 ) [HTML 0KB] [PDF 734KB ]( 21 )

	1527	ZHANG Ye, FENG ShiGang, FENG HongBo, DONG Feng and TANG YiYuan
		The task dependent interaction of the deactivation regions
		Although deactivation has been found frequently in former functional brain imaging researches, only recently has it become a focus of systematic study because of its not well understood physiological mechanism. However, most of the researches concentrated on the brain areas that would present deactivation, and, to our knowledge, the deactivation connectivity between these brain areas during the cognitive tasks has rarely been reported in literature. In this work, using the functional connectivity method WICA (within-condition interregional covariance analysis), we analyzed the deactivations in two different cognitive tasks――symbol orientation and number comparison. The results revealed deactivations in the posterior cingulate, precuneus, anterior cingulate and prefrontal cortex in both tasks. However, the interaction between the deactivated regions shows many differences. Our result further indicates that the potential implication of special deactivation connectivity may be related to the different task or attention resource. Further research is needed to clarify the exact reason.
		2008 Vol. 53 (10): 1527-1532 [Abstract ] ( 53 ) [HTML 0KB] [PDF 974KB ]( 21 )

	1533	CHEN GuoCheng, ZHENG HongBo, LI JianRu, XIE Xin and MEI Xi
		Dynamic control on grain-size distribution of terrigenous sediments in the western South China Sea: Implication for East Asian monsoon evolution
		High-resolution oxygen isotope stratigraphy of Core MD05-2901, which is located off eastern Vietnam in the western South China Sea (SCS), was established and indicated that the core spans a time period of the past 450 ka. Based on the bulk density, fractional porosity and lithogenic content of the sedi-ments, terrigenous mass accumulation rate (TMAR) was obtained, which is 4.9―6.0 g cm^-2 ka^-1 on average during interglacial stages, higher than that during glacial stages, i.e. 1.9―5.0 g cm^-2 ka^-1, which is different from northern and southern SCS which show higher TMAR in glacial stages. By principle component analysis of grain size distribution of all the samples, two main control factors (F1 and F2) were obtained, which are responsible for about 80% variance of granularity. The contents of grain size population 1.26―2.66 μm% and 10.8―14.3 μm% which are sensible to F1 show high-frequency fluctuation, and correlate well with the summer insolation at 15ºN. They exhibit a dis-tinct cyclicity with frequencies near 23 ka and 13 ka, in contrast to a strong frequency peak near 100 ka obtained in proxies 4.24―7.42 μm% and 30.1―43.7 μm% controlled mainly by F2. The sedimentary character of this part of the SCS was controlled by variations of input flux from two main source areas, namely the southwest and north SCS, which were transported by different circulations of surface cur-rent forced by East Asian summer monsoon and winter monsoon respectively. We believe that the East Asian summer monsoon has fluctuated with high frequency and been forced by changes in solar in-solation in low latitude associated with precession and half precession, while ice-volume forcing is probably a primary factor in determining the strength and timing of the East Asian winter monsoon but with less important insolation forcing.
		2008 Vol. 53 (10): 1533-1543 [Abstract ] ( 55 ) [HTML 0KB] [PDF 1310KB ]( 19 )

	1544	ZHAO JunMeng, CHENG HongGang, PEI ShunPing, LIU HongBing, ZHANG JianShi and LIU BaoFeng
		Deep structure at northern margin of Tarim Basin
		In this paper, a 2D velocity structure of the crust and the upper mantle of the northern margin of the Tarim Basin (TB) has been obtained by ray tracing and theoretical seismogram calculation under the condition of 2D lateral inhomogeneous medium using the data of seismic wide angle reflection/refrac- tion profile from Baicheng to Da Qaidam crossing the Kuqa Depression (KD) and Tabei Uplift (TU). And along the Baicheng to Da Qaidam profile, 4 of the 10 shot points are located in the northern margin of the TB. The results show that the character of the crust is uniform on the whole between the KD and TU, but the depth of the layers, thickness of the crust and the velocity obviously vary along the profile. Thereinto, the variation of the crust thickness mainly occurs in the middle and lower crust. The Moho has an uplifting trend near the Baicheng shot point in KD and Luntai shot point in TU, and the thickness of the crust reduces to 42 km and 47 km in these two areas, respectively. The transition zone between the KD and TU has a thickest crust, up to 52 km. In this transition zone, there are high velocity anoma-lies in the upper crust, and low velocity anomalies in the lower crust, these velocity anomalies zone is near vertical, and the sediment above them is thicker than the other areas. According to the velocity distributions, the profile can be divided into three sections: KD, TU and transition zone between them. Each section has a special velocity structural feature, the form of the crystalline basement and the re-lationship between the deep structure and the shallow one. The differences of velocity and tectonic between eastern and western profile in the northern margin of the Tarim Basin (NMTB) may suggest different speed and intensity of the subduction from the Tarim basin to the Tianshan orogenic belt (TOB).
		2008 Vol. 53 (10): 1544-1554 [Abstract ] ( 57 ) [HTML 0KB] [PDF 2006KB ]( 19 )

	1555	HU ShouYun, DUAN XueMei, SHEN MingJie, U BLAHA, W ROESLER, YAN HaiTao, E APPEL and V HOFFMANN
		Magnetic response to atmospheric heavy metal pollu-tion recorded by dust-loaded leaves in Shougang in-dustrial area, western Beijing
		Fifty-five evergreen tree’s leaves growing less than one year were collected from Shougang industrial area in western suburb of Beijing, including steel plants and its ambient residential areas, recreational parks and farmlands. Rock magnetic properties and heavy metal contents were studied. The results show that the magnetic properties of leaf samples are predominated by low-coercivity magnetite, and both the concentration and grain size of magnetite particles gradually decreased with the distance from the main pollution source increases. Moreover, there is a significant linear relationship between mag-netic parameters (the low-field magnetic susceptibility, saturation isothermal remanent magnetization and anhysteretic remanent magnetization) and heavy metals contents (Fe, Pb, V, Cr and Zn) (0.73≤R≤ 0.88). Hence, the magnetic parameters of leaves can serve as a proxy for quick detecting of the recent atmospheric metallic pollution.
		2008 Vol. 53 (10): 1555-1564 [Abstract ] ( 59 ) [HTML 0KB] [PDF 539KB ]( 21 )

	1565	XIE LieWen, ZHANG YanBin, ZHANG HuiHuang, SUN JingFeng and WU FuYuan
		In situ simultaneous determination of trace elements, U-Pb and Lu-Hf isotopes in zircon and baddeleyite
		This paper describes a combined method of simultaneously measuring U-Pb and Lu-Hf isotopes as well as trace elements in Phalaborwa baddeleyite and 91500, GJ-1, TEMORA-1 and SK10-2 zircons by means of Neptune MC-ICPMS and Agilent Q-ICPMS connected to a 193 nm excimer laser ablation system. Material ablated by laser was carried in different proportions into Q-ICPMS for U-Pb isotopic and trace elemental and MC-ICPMS for Lu-Hf isotopic compositions. Experiments indicate that different proportions of ablated material for the Q-ICPMS and MC-ICPMS (6:4, 5:5 and 4:6 respectively) do not show any bias for the zircon/baddeleyite U-Pb age, Lu-Hf isotope and trace elemental compositions within analytical errors. Using 40―60 μm spot size, the obtained U-Pb ages of Phalaborwa baddeleyite, 91500, GJ-1, TEMORA and SK10-2 zircons are 2065±15 (2σ, n=20), 1063±6 (2σ, n=19), 613±6 (2σ, n=20), 416±5 (2σ, n=20) and 32.6±0.5 (2σ, n=20) Ma, respectively. The ¹⁷⁶Hf/¹⁷⁷Hf ratios are 0.281231±24 (2SD, n=20), 0.282310±35 (2SD, n=19), 0.282028±34 (2SD, n=20), 0.282687±34 (2SD, n=20) and 0.282752±53 (2SD, n=20), respectively. The obtained trace elemental compositions are identical to the reference values. Therefore, this kind of technique makes it possible to simultaneously obtain the U-Pb age, Lu-Hf isotopes and trace elemental compositions of zircon and baddeleyite, which could be an important tool in solving problems in earth sciences.
		2008 Vol. 53 (10): 1565-1573 [Abstract ] ( 54 ) [HTML 0KB] [PDF 1388KB ]( 16 )

	1574	ZHENG YongGuang, CHEN Jiong and ZHU PeiJun
		Climatological distribution and diurnal variation of mesoscale convective systems over China and its vicinity during summer
		The climatological distribution of mesoscale convective systems (MCSs) over China and its vicinity during summer is statistically analyzed, based on the 10-year (1996―2006, 2004 excluded) June-August infrared TBB (Temperature of black body) dataset. Comparing the results obtained in this paper with the distribution of thunderstorms from surface meteorological stations over China and the distribution of lightning from low-orbit satellites over China and its vicinity in the previous studies, we find that the statistic characteristics of TBB less than -52℃ can better represent the spatiotemporal distribution of MCSs over China and its vicinity during summer. The spreading pattern of the MCSs over this region shows three transmeridional bands of active MCSs, with obvious fluctuation of active MCSs in the band near 30°N. It can be explained by the atmospheric circulation that the three bands of active MCSs are associated with each other by the summer monsoon over East Asia. We focus on the diurnal variations of MCSs over different underlying surfaces, and the result shows that there are two types of MCSs over China and its vicinity during summer. One type of MCSs has only one active period all day long (single-peak MCSs), and the other has multiple active periods (multi-peak MCSs). Single-peak MCSs occur more often over plateaus or mountains, and multi-peak MCSs are more common over plains or basins. Depending on lifetimes and active periods, single-peak MCSs can be classified as Tibetan Plateau MCSs, general mountain MCSs, Ryukyu MCSs, and so on. The diurnal variation of multi-peak MCSs is very similar to that of MCCs (mesoscale convective complexes), and it reveals that multi-peak MCSs has longer life cycle and larger horizontal scale, becomes weaker after sunset, and develops again after midnight. Tibetan Plateau MCSs and general mountain MCSs both usually develop in the afternoon, but Tibetan Plateau MCSs have longer life cycle and more active MaCSs. Ryukyu MCSs generally develop after midnight, last longer time, and also have more active MaCS. The abundant moisture and favorable large-scale environment over Indian monsoon surge areas lead to active MCSs and MaCSs almost at any hour all day during summer. Due to local mountain-valley breeze circulation over the Sichuan Basin, MCSs are developed remarkably more often during the nighttime, and again there are also more active MaCSs. Because of local prominent sea-land breeze circulation over Guangxi and Guangdong, the MCSs over this region propagate from sea to land in the afternoon and from land to sea after midnight. The statistic characteristics of TBB less than -52℃ clearly display the different climatological characteristics of MCSs owing to the thermal difference among water, land and rough terrain. Not only the large-scale atmospheric circulation but also the local atmospheric circulation caused by the thermal difference among water, land and rough terrain, to a great extent, determines the climatological distribution of MCSs over China and its vicinity during summer.
		2008 Vol. 53 (10): 1574-1586 [Abstract ] ( 59 ) [HTML 0KB] [PDF 3870KB ]( 19 )

	1587	HAN Xin, ZHANG DeYuan, LI Xiang and LI YuanYue
		Bio-replicated forming of the biomimetic drag-reducing surfaces in large area based on shark skin
		On the investigation of biomimetic drag-reducing surface, direct replication of the firm scarfskins on low-resistance creatures to form biomimetic drag-reducing surfaces with relatively vivid morphology relative to the living prototype is a new attempt of the bio-replicated forming technology. Taking shark skin as the bio-replication template, the hot embossing method was applied to the micro-replication of its outward morphology. Furthermore, the skins were jointed together to form the drag-reducing surface in large area. The results of the resistance measurements in a water tunnel according to the flat-plate sample pieces have shown that the biomimetic shark-skin coating fabricated by the bio-replicated forming method has significant drag reduction effect, and that the drag reduction efficiency reached 8.25% in the test conditions.
		2008 Vol. 53 (10): 1587-1592 [Abstract ] ( 56 ) [HTML 0KB] [PDF 2420KB ]( 22 )

	1593	YU DunXi, XU MingHou, YAO Hong, LIU XiaoWei and ZHOU Ke
		Effective identification of the three particle modes generated during pulverized coal combustion
		Based on the mass fraction size distribution of aluminum (Al), an improved method for effectively identifying the modes of particulate matter from pulverized coal combustion is proposed in this study. It is found that the particle size distributions of coal-derived particulate matter actually have three modes, rather than just mere two. The ultrafine mode is mainly generated through the vaporization and condensation processes. The coarse mode is primarily formed by the coalescence of molten minerals, while the newly-found central mode is attributed to the heterogeneous condensation or adsorption of vaporized species on fine residual ash particles. The detailed investigation of the mass fraction size distribution of sulfur (S) further demonstrates the rationality and effectiveness of the mass fraction size distribution of the Al in identifying three particle modes. The results show that not only can the number of particle modes be identified in the mass fraction size distributions of the Al but also can their size boundaries be more accurately defined. This method provides new insights in elucidating particle formation mechanisms and their physico-chemical characteristics.
		2008 Vol. 53 (10): 1593-1602 [Abstract ] ( 53 ) [HTML 0KB] [PDF 774KB ]( 22 )

	1603	WANG JiaDao, CHEN HaoSheng, QIN Li, LI YongJian and CHEN DaRong
		Key roles of micro-particles in water on occurrence of cavitation-erosion of hydro-machinery
		It has been believed for about one hundred years that the cavitation directly induces the cavitation erosion. It is proposed in this research that cavitation is only the necessary condition but not the sufficient condition of the cavitation erosion. The experiment performed on the rotary disk cavitation system shows that the mi-cro-particles in the fluid play indispensable roles in the cavitation erosion process, and the generation of the erosion pits on the steel surface is also affected by the particles’ size. These cracks and deformations on the sample surface indicate that the erosion is the result of the mechanical behavior. Numerical calculations are also provided to support this mechanism.
		2008 Vol. 53 (10): 1603-1607 [Abstract ] ( 53 ) [HTML 0KB] [PDF 886KB ]( 17 )

	1608	LI Yi, LING ZhiYuan, WANG JinChi, CHEN ShuoShuo, HU Xing and HE XinHua
		Fabrication of porous alumina templates with a large-scale tunable interpore distance in a H₂C₂O₄-C₂H₅OH-H₂O solution
		Highly ordered porous alumina templates with a large-scale tunable interpore distance (100―445 nm) have been successfully fabricated under an electric field of 40―180 V by modifying oxalic acid solution with adequate alcohol. The results under our experimental conditions show that the phenomena of burning and breakdown during the high-field anodization process can be avoided by adding a proper amount of alcohol to the oxalic acid solution. An excellent linear relationship between interpore distance and anodization voltage is obtained under 40―170 V, and the maximum anodization voltage that could be used to avoid burning and breakdown is 180 V.
		2008 Vol. 53 (10): 1608-1612 [Abstract ] ( 49 ) [HTML 0KB] [PDF 1810KB ]( 18 )

BRIEF COMMUNICATION

	1613	LI YiBao, ZENG QingDao, WANG ZhiHui, QI GuiCun, GUAN Li, FAN XiaoLin and WANG Chen
		Constructing supramolecular nanostructure by hydrogen-bonding
		The diquinoxalino (2.3-2′.3′-a.c) phenazine (DQP), containing 6 nitrogen atoms, was synthesized, and its adsorption and self-assembling behavior on highly oriented pyrolytic graphite (HOPG) was studied by scanning tunneling microscopy (STM) under ambient conditions. With 1,14-tetradecanedioic acid as a bridge, uniform two-dimensional arrays of 1,14-tetradecanedioic acid/DQP nanostructure were suc-cessfully fabricated. The result illustrates that it is possible to construct and control supramolecular nanostructure by intermolecular hydrogen-bonding.
		2008 Vol. 53 (10): 1613-1616 [Abstract ] ( 59 ) [HTML 0KB] [PDF 475KB ]( 28 )

Username:

Password:

·	(2007-4-5)

·	(2007-4-5)

·	(2007-4-5)

More>>

·	科学家将建海底观测站欲揭海洋之谜(图)(2007-7-27)

More>>