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Effect of different water supply on morphology, growth and physiological characteristics of Salix psammophila seedlings in Maowusu sandland, China

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Journal of Environmental Sciences 2001年第4期13卷 411-417页

作者： Xiao, C.-w. Lab. Quantitative Vegetation Ecol. Institute of Botany Chinese Academy of Sciences Beijing 100093 China

Response pattern was investigated for seedlings of Salix psammophila, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. The growth characters, in terms of plant height, stem diameter, total branch number, total leaf number and area, total bifurcation ratio, total branch lenght and branch number, branch lenght, leaf number and leaf area of each branch order, and leaf, branch and root biomass significantly increased when water supply increased. That water supply had significant effect on biomass allocation showed different investment pattern of biomass resource of the seedlings grown under different water supply treatments. Stomatal density of abaxial leaf surface decreased, and stomatal apparatus length and width of adaxial and abaxial leaf surface increased with the increase of water supply, while Stomatal density of adaxial leaf surface was not affected by water supply. water supply obviously affected the diumal changes of photosynthetic rate, and the photosynthetic rate of the seedlings showed strongly midday depression grown under the 157.5 mm water supply, but not grown under higher water supply. Additionally the assimilation-light response curves and flourescence efficiency more showed that water supply improve photosynthesis capacity. Finally, S. psammophila seedlings stood out by their slow growth and relatively high investments in root growth in order to reduce tissue losing rate and consumption of water resource for keeping water balance under water stress. The seedlings that grown under rich water supply did by their fast growth and relatively high investments in branch and leaf growth in order to improve the power of capturing light energy for higher photosynthesis.

关键词： Biomass Fluorescence Morphology Photosynthesis Physiology Plants (botany) Precipitation (chemical) Seed Tissue

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Do increasing respiratory costs explain the decline with age of forest growth rate?

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Journal of Forestry Research 2020年第3期31卷 693-712页

作者： P.w.west Forest research centre southern cross universitylismorensw 2480australia

Once forests have achieved a full canopy, their growth rate declines progressively with age. This work used a global data set with estimates from a wide range of forest types, aged 20-795 years, of their annual photosynthetic production(gross primary production, GPP) and subsequent above-plus below-ground biomass production(net primary production, NPP). Both GPP and NPP increased with increasing mean annual temperature and precipitation. GPP was then unrelated to forest age whilst NPP declined progressively with increasing age. These results implied that autotrophic respiration increases with age. It has been proposed that GPP should decline in response to increasing water stress in leaves as water is raised to greater heights as trees grow taller with age. However, trees may make substantial plastic adjustment in mor phology and anatomy of newly developing leaves, xylem and fi ne roots to compensate for this stress and maintain GPP with age. This work reviews the possibilities that NPP declines with age as respiratory costsincrease progressively in, any or all of, the construction and maintenance of more complex tissues, the maintenance of increasing amounts of live tissue within the sapwood of stems and coarse roots, the conversion of sapwood to hear twood, the increasing distance of phloem transport, increased turnover rates of fine roots, cost of supporting very tall trees that are unable to compensate fully for increased water stress in their canopies or maintaining alive competitively unsuccessful small trees.

关键词： Primary production Photosynthesis Respiration Biomass growth Ageing

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Enhancement of Gain in L-Band Bismuth-Based Erbium-Doped Fibre Amplifier Using an Un-pumped EDF and Midway Isolator

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Chinese Physics Letters 2004年第12期21卷 2452-2453页

作者： w.Y.Chong S.w.Harun H.Ahmad PhotonicsLaboratory DepartmentofPhysicsUniversityofMalaya50603KualaLumpur FacultyofEngineering MultimediaUniversityJalanMultimedia63100CyberjayaSelangorMalaysia

A hybrid L-band erbium-doped fibre amplifier (EDFA) with enhanced gain characteristic is demonstrated without a significant noise figure penalty. It uses a backward C-band amplified stimulated emission from both the ends of a bismuth-based EDFA system to pump an unpumped erbium-doped fibre (EDF) for gain enhancing. The maximum gain enhancement of 4.0dB is obtained at wavelength 1604nm with EDF length of 20m. The gain spectrum is reasonably flat in this amplifier compared with the amplifier without an EDF. The gain varies from 27.4dB to 30.2dB at wavelength region 1564--1608nm with incorporation of 20m EDF. Noise figure also varies from 6.0 to 7.7dB at this wavelength region.

关键词： Condensed matter: electrical magnetic and optical Optics quantum optics and lasers

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Secondary steady-state and time-periodic flows from a basic flow with square array of odd number of vortices

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Applied Mathematics and Mechanics(English Edition) 2023年第3期44卷 447-458页

作者： Zhimin CHEN w.G.PRICE School of Mathematics and Statistics Shenzhen UniversityShenzhen 518060Guangdong ProvinceChina Ship Science University of SouthamptonSouthampton SO171BJU.K.

In a magnetohydrodynamic(MHD)driven fluid cell,a plane non-parallel flow in a square domain satisfying a free-slip boundary condition is *** energy dissipation of the flow is controlled by the viscosity and linear *** latter arises from the influence of the Hartmann bottom boundary layer in a three-dimensional(3D)MHD experiment in a square bottomed *** basic flow in this fluid system is a square eddy flow exhibiting a network of N~2 vortices rotating alternately in clockwise and anticlockwise *** N is odd,the instability of the flow gives rise to secondary steady-state flows and secondary time-periodic flows,exhibiting similar characteristics to those observed when N=*** this reason,this study focuses on the instability of the square eddy flow of nine *** is shown that there exist eight bi-critical values corresponding to the existence of eight neutral eigenfunction ***,there exist non-real neutral eigenfunctions,which produce secondary time-periodic flows exhibiting vortices merging in an oscillatory *** Hopf bifurcation phenomenon has not been observed in earlier investigations.

关键词： two-dimensional(2D)Navier-Stokes equation non-parallel square vortex flow primary bifurcation secondary steady-state flow secondary time-periodic flow

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Feasibility Study of Using DLC Coating in Conjunction with Laser Ablation process to Improve the Tribological Performance of an Engineering Surface

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稀有金属材料与工程 2012年第S1期41卷 52-56页

作者： Shum P w Department of Manufacturing Engineering and Engineering Management(MEEM) City University of Hong KongHong KongChina

Increasing demands such as low friction,low wear rate,and long life-time have reached the limits of single DLC *** order to meet the requirements,we propose to use an integrated approach to improve the wear property of an engineering ***,dimples are introduced perpendicular to an engineering surface by a Nd:YAG laser emitting at 1064 ***,solid lubricant DLC is prepared on the patterned surface by magnetron sputtering *** effect of dimple densities from 7%to 45 %on tribological properties of the coating surface was *** wear performance of the textured DLC surfaces was studied by a pin-on-disk reciprocating sliding wear tester under boundary lubrication and dry *** results showed that the DLC coatings with appropriate dimple densities have an obvious improvement on wear performance in term of friction coefficient,wear rate and wear life,as compared to un-textured DLC *** boundary lubrication conditions,the improved wear performance can be explained by the promotion of reservoirs to enhance lubricant retention during *** dry condition,the dimples trap wear particles and leave a free interface between pin and sliding contact surface,and avoid the surface worn by abrasive manner,thereby improving the wear performance of the DLC coating.

关键词： laser wear DLC

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Experimental Study of Inducing Compressive Stress by Anti-welding Heating Treatment in a Thin Plate weldment with Variant Temperatures

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Journal of Materials Science & Technology 2002年第2期18卷 151-154页

作者： HuainingCHEN w.Fricke 等 InstituteofMetalResearch ChineseAcademyofSciencesShenyang110016China DepartmentofShipstructuresandStructuralAnalysis TUHH22305HamburgGermany

Significant compressive stress may be induced in thin plate weldment by anti-welding heating treatment (AwHT) with a temperature difference above 350℃, and an interesting phenomenon of obvious residual stress reduction on non-treated surface was discovered. The method of AwHT has no great effect on the mechanical properties including hardness, strength and toughness of the metal material. The results in the paper prompt a possibility application in shipbuilding industry.

关键词： Experimental study Auti-welding heating treatment Thin plate weldment welding residual stress

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Special Effect of Parallel Inductive Electric Field

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Chinese Physics Letters 2002年第6期19卷 881-884页

作者：陈涛 w.Heikkila 等 CenterforSpaceScienceandAppliedResearch ChineseAcademyofSciencesPOBox8701Beijing100080 CenterForSpaceSciences UniversityofTexasatDallasRichardsonTexas75083USA

Acceleration of electrons by a field-aligned electric field during a magnetospheric substorm in the deep geomagnetic tail is studied by means of a one-dimensional electromagnetic particle code. It was found that the free acceleration of the electrons by the parallel electric field is obvious; kinetic energy variation is greater than electromagnetic energy variation in the presence of parallel electric field. Magnetic energy is greater than kinetic energy variation and electric energy variation in the absence of the parallel electric field. More wave modes in the presence of the parallel electric field are generated than those in the absence of the parallel electric field.

关键词： GEOMAGNETIC TAIL acceleration Electrons Electric fields wave mode Variation Electromagnetic Energies magnetic energy Parallel Lines MAGNETOTAIL electrical energy

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Dynamic experiment and numerical simulation of frozen soil under confining pressure

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Acta Mechanica Sinica 2020年第6期36卷 1302-1318,I0004页

作者： w.R.Tang Z.w.Zhu T.T.Fu Z.w.Zhou Z.H.Shanggua Applied Mechanics and Structural Safety Key Laboratory of Sichuan Province School of Mechanics and EngineeringSouthwest Jiaotong UniversityChengdu610036China Northwest Institute of Eco-Environment and Resources State Key Laboratory of Frozen Soil EngineeringChinese Academy of SciencesLanzhou730000China

with the development of cold region engineering,it is crucial to study the mechanical properties of frozen *** practice,frozen soil is inevitably subject to impact loading,making the study of frozen soil under impact loading necessary for engineering in cold *** split–Hopkinson pressure bar(SHPB)is an important experimental means for obtaining the dynamic performance of *** this study,an SHPB experiment was conducted on frozen soil under confining *** frozen soil exhibited an evident strain rate effect and temperature effect under confining *** SHPB experiment on frozen soil under confining pressure was simulated numerically using LS-DYNA software and the Holmquist–Johnson–Cook(HJC)material model.A loading simulation with passive confining pressure and active confining pressure was completed by adding an aluminum sleeve and applying a constant *** simulation results obtained using the above methods were in good agreement with the experimental *** strength of the frozen soil under confining pressure was greater than that of the uniaxial impact,and there was an evident confining pressure ***,the confining pressure provided by passive confinement was larger than that provided by active *** passive confining pressure energy absorption efficiency was higher than for the active confining pressure due to the need to absorb more energy under the same damage *** frozen soil exhibited viscoplastic failure characteristics under confining pressure.

关键词： Frozen soil-Dynamic experiment Confining pressure Split-Hopkinson pressure bar Numerical simulation

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Multiple Antibiotic Resistance and Heavy Metal Resistance Profile of Bacteria Isolated from Giant Freshwater Prawn (Macrobrachium rosenbergii) Hatchery

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Agricultural Sciences in China 2009年第6期8卷 740-745页

作者： S w Lee M Najiah w wendy A Zahrol M Nadirah Department of Fishery and Aquaculture Faculty of Agrotechnology and Food Science Universiti Malaysia Terengganu

In this article, antibiogram and heavy metal resistance profile of bacteria isolated from giant freshwater prawn （Macrobrachium rosenbergii） hatchery in Malaysia are described. Although giant freshwater prawn was introduced into Malaysia since the 1980s, there was no database information on antibiogram and heavy metal resistance profile of bacteria from giant freshwater prawn （34. rosenbergii） hatchery in Malaysia. Therefore, this study was carried out to determine the effectiveness of antibiotic and heavy metal resistance profile to control bacterial diseases in M. rosenbergii hatchery. The results can provide valuable information for local M. rosenbergii post-larval producer. Antibiotic sensitivity test was carried out by disk-diffusion method against 15 types of antibiotics as follows： oxolinic acid （2 μg）, ampicillin （10μg）, erythromycin （15μg）, furazolidone （15 μg）, lincomycin （15μg）, amoxicillin （25 μg）, colistin sulphate （25 μg）, doxycycline （30μg）, florfenicol （30 μg）, flumequine （30 lag）, nalidixic acid （30μg）, tetracycline （30μg）, oleandomycin （15μg）, fosfomycin （50μg）, and spiramycin （100 μg）, whereas heavy metal resistance profile of the present bacterial isolates was determined by 2-fold agar dilution technique. In this study, 5 types of bacteria were successfully isolated; they were Aeromonas spp. （n = 77）, Escherichia coli （n = 73）, Edwardsiella spp. （n = 62）, Salmonella spp. （n = 75）, and Vibrio spp. （n = 43）. The result showed that furazolidone was the most effective antibiotic to control the bacteria isolated in this study, approximately 89.7% of the bacterial isolates were sensitive to this antibiotic. Multiple antibiotic resistance （MAR） index indicated that the hatchery water source and M. rosenbergii post-larval and sediment tanks were at high-risk exposure to the tested antibiotic. Furthermore, all the tested heavy metals （Cd2＋, Cr6＋, Hg2＋, and Cu2＋） failed to inhibit the growth of the bacterial isolates. Therefore, it indicated that the water

关键词： Macrobrachium rosenbergii hatchery antibiotic heavy metal MAR index

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CALCULATION OF THE VACANCY VOLUME OF METALS BY MODIFIED BROOKS' MODEL

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 888-893页

作者： w.H.Qi M.P.wang w.Y.Hu B.w.Zhang SchoolofMaterialsScienceandEngineering JiangsuUniversityZhenjiang212013China／／SchoolofMaterialsScienceandEngineeringCentralSouthUniversityChangsha410083China SchoolofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China DepartmentofAppliedPhysics HunanUniversityChangsha410082China

To modify the shape difference between the spherical vacancy and the realistic vacancy, a shape factor is introduced into Brooks' vacancy model. It is shown that the modified model is more efficient in predicting the vacancy volume of metals than the original one, and the calculated vacancy volumes of 17 metals by the modified model agree with the values reported in literatures. Furthermore, the present results show that the vacancy shape may contribute 2%-9% to the whole vacancy volume.

关键词： vacancy volume shape effect metals

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