Toward an understanding of the turbidity measurement of fleterocoagulation rate constants of dispersions containing particles of different sizes

Our previous studies have shown that the determination of coagulation rate constants by turbidity measurement becomes impossible for a certain operating wavelength (that is, its blind point) because at this wavelength the change in the turbidity of a dispersion completely loses its response to the coagulation process. Therefore, performing the turbidity measurement in the wavelength range near the blind point should be avoided. In this article, we demonstrate that the turbidity measurement of the rate constant for coagulation of a binary dispersion containing particles of two different sizes (heterocoagulation) presents special difficulties because the blind point shifts with not only particle size but also with the component fraction. Some important aspects of the turbidity measurement for the heterocoagulation rate constant are discussed and experimentally tested. It is emphasized that the T-matrix method can be used to correctly evaluate extinction cross sections of doublets formed during the heterocoagulation process, which is the key data determining the rate constant from the turbidity measurement, and choosing the appropriate operating wavelength and component fraction are important to achieving a more accurate rate constant. Finally, a simple scheme in experimentally determining the sensitivity of the turbidity changes with coagulation over a wavelength range is proposed.

In situ surface topography measurement method of granite base in scanning wafer stage with laser interferometer

Topography of a granite surface has an effect on the vertical positioning of a wafer stage in a lithographic tool, when the wafer stage moves on the granite. The inaccurate measurement of the topography results in a bad leveling and focusing performance. In this paper, an in situ method to measure the topography of a granite surface with high accuracy is present. In this method, a high-order polynomial is set up to express the topography of the granite surface. Two double-frequency laser interferometers are used to measure the tilts of the wafer stage in the X- and Y-directions. From the sampling tilts information, the coefficients of the high-order polynomial can be obtained by a special algorithm. Experiment results shows that the measurement reproducibility of the method is better than 10 nm. (c) 2006 Elsevier GmbH. All rights reserved.

Taxonomic problems in the Drosophila melanica species group (Diptera : Drosophilidae) from southern China, with special reference to karyotypes and reproductive isolation

Karyotypes and reproductive isolation were studied in two allopatric populations of Drosophila tsigana, one from Guizhou Province in southern China and the other from Hokkaido in northern Japan, and in one population of a closely related species, D. longi

Molecular systematics of Xenocyprinae (Teleostei : Cyprinidae): Taxonomy, biogeography, and coevolution of a special group restricted in east Asia

We surveyed mitochondrial DNA (mtDNA) sequence variation in the subfamily Xenocyprinae from China and used these data to estimate intraspecific, interspecific, and intergeneric phylogeny and assess biogeographic scenarios underlying the geographic structure of lineages. We sequenced 1140 bp of cytochrome b from 30 individuals of Xenocyprinae and one putative outgroup (Myxocypris asiaticus) and also sequenced 297 bp of ND4L, 1380 bp of ND4, 68 bp of tRNA(His), and 69 bp of tRNA(Ser) from 17 individuals of Xenocyprinae and the outgroup (M. asiaticus). We detected high levels of nucleotide variation among populations, species, and genera. The phylogenetic analysis suggested that Distoechodon hupeinensis might be transferred to the genus Xenocypris, the taxonomic status of the genus Plagiognathops might be preserved, and species of Xenocypris and Plagiognathops form a monophyletic group that is sister to the genus Distoechodon and Pseudobrama. The introgressive hybridization might occur among the populations of X. argentea and X. davidi, causing the two species to not be separated by mtDNA patterns according to their species identification, and the process and direction of hybridization are discussed. The spatial distributions of mtDNA lineages among populations of Xenocypris were compatible with the major geographic region, which indicated that the relationship between Hubei + Hunan and Fujian is closer than that between Hubei + Hunan and Sichuan, From a perspective of parasite investigation, our data suggested that the fauna of Hexamita in Xenocyprinae could be used to infer the phylogeny of their hosts. (C) 2001 Academic Press.

Measurement of polar C-plane and nonpolar A-plane InN/ZnO heterojunctions band offsets by x-ray photoelectron spectroscopy

The valence band offsets of the wurtzite polar C-plane and nonpolar A-plane InN/ZnO heterojunctions are directly determined by x-ray photoelectron spectroscopy to be 1.76 +/- 0.2 eV and 2.20 +/- 0.2 eV. The heterojunctions form in the type-I straddling configuration with a conduction band offsets of 0.84 +/- 0.2 eV and 0.40 +/- 0.2 eV. The difference of valence band offsets of them mainly attributes to the spontaneous polarization effect. Our results show important face dependence for InN/ZnO heterojunctions, and the valence band offset of A-plane heterojunction is more close to the "intrinsic" valence band offset.

Back-to-back Schottky diode adopted for the measurement of GaN films and its Schottky contacts

A new measurement method for GaN films and their Schottky contacts is reported in this paper. Instead of the fabrication of Ohmic contacts, this measurement is based on a special back-to-back Schottky diode that has a rectifying character. A mathematical model indicates that the electronic parameters of the materials can be deduced from the device's I-V data. In the experiment of an unintentionally doped n-type GaN layer with a residual carrier density 7 x 10(16) cm(-3), the analysis by the new method gives the layer's sheet resistance rho(s) = 497 Omega, the electron mobility mu(n) =, 613 cm(2) V-1 s(-1) and the ideality factor of the Ni/Au-GaN Schottky contacts n = 2.5, which are close to the data obtained by the traditional measurements: rho(s) = 505 Omega, mu(n) = 585 cm(2) V-1 s(-1) and n = 3.0. The method reported can be adopted not only for GaN films but also for other semiconductor materials, especially in the cases where Ohmic contacts of high quality are hard to make or their fabricating process affects the film's character.

Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being -0.30 +/- A 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 +/- A 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices.

川西亚高山森林生态系统辐射传输研究

辐射传输研究是贯穿森林生态系统的纽带，太阳辐射为植物的生长发育提供光合能量、适宜的环境温度以及发育信息。一方面，气候变化使到达地面辐射能的质和量发生变化，影响到植被的生长发育，改变森林的结构，而森林结构的变化又会影响林冠内辐射能的分配和质量，这些变化会进一步影响到林下土壤温度，改变森林根系活性以及土壤营养转化的效率；连锁反应的结果有可能会使森林生态系统的生产力发生变化，改变碳素和氮素源库的调节方向，从而反馈影响地球气候系统。另一方面，人类作为生态系统的成员，必然需要森林生态系统为其提供更多的原材料和更好的生态服务功能，如何实现这些目标，就需要人类适度调整干预方式和频度，达到预期的目的。本文在建立适合于川西亚高山森林的叶面积测量技术、光照辐射模型和土壤温度变化模型的基础上，对川西亚高山地带森林生态系统的辐射传输特征进行了分析，并从森林结构的角度探讨了林分内的辐射分布以及对土壤温度的影响。主要成果如下： 1. 提出了一种照相法测量叶面积的方法。通过对摆放在平面上的叶片照相，利用投影变化，把非正射图像转化为正射图像，然后经过计算机图像处理得到每一片叶片的面积、周长、长度、宽度等信息。这种方法可使用户以任意方向和距离拍摄处于平面上的叶片，能同时处理大量的叶片，适于野外离体或活体叶片测量。叶片面积分辨率可调，分辨率可以与常用的激光叶面积仪相近甚至更高，而且叶片图像可以存档查询。 2. 提出一种模拟林内光照变化的模型。利用林冠半球照片，记录视点以上半球内的林冠构件空间分布，作为林冠子模型；天空辐射子模型采用国际照明委员会(CIE)的标准晴天和阴天以及插值模型。该模型能够模拟林下某一位点处的实时光斑变化。 3. 提出一种土壤温度变化模型。把土壤视为具有容量和阻力性质的结构，利用电阻和电容器件构建土壤能量分布模型。外界太阳辐射能经过植被以及其它一些能量分配器后进入土壤，其中有一部分转化为土壤势能，即土壤温度。土壤温度的变化类似于电池的充放电过程。在已知模型参数的情况下，可以从太阳辐射计算土壤温度的变化。在模型参数未知的情况下，通过输入和输出值推算模型的参数，而模型参数中的时间常数与土壤组成和含水量有关，这样就可以知道土壤水分的变化情况。 4. 从王朗亚高山森林典型样地林分结构的测量获得林地三维结构图、树冠形态、叶面积密度等参数，这些参数输入到Brunner (1998)开发的tRAYci 模型中计算出一段时间内林分任意位置处的光照值。与林下辐射计测量值以及半球照片计算结果的比较，该模型基本上能够满足对林分光环境了解的要求。 5. 从川西亚高山森林生产力的角度，探讨了森林生产力研究的方法以及川西地区的研究历史和成果，发现了其中的一些规律和问题，特别是在叶面积测量上，还没有使用标准的叶面积指数定义。综合来看，川西地区针叶林叶面积指数(单位土地面积上植物冠层总叶面积的一半) 应在4-5 之间。降雨丰富的华西雨屏带是川西地区森林生产力最高的地区，而向西北森林生产力逐渐降低。川西地区云冷杉林森林生产力平均约为600 gDM m-2 a-1，但是根据辐射能计算的潜在生产力则达到1800 gDM m-2 a-1。实际与潜在森林生产力的巨大差异说明其它因子对生产力的影响。 6. 王朗亚高山3 个典型森林林分中，白桦林样地(BF) 林下草本以糙野青茅、牛至、紫菀等喜阳性物种为主，林下透光度较高；冷杉林样地(FF) 林下透光度最低，以喜阴性物种水金凤、蟹甲草、囊瓣芹等为主；而云杉林样地(SF)林分林龄最大，林下透光度介于冷杉林和白桦林之间，草本层仍然以喜阴性物种东方草莓、紫花碎米芥、酢浆草等为主。冷杉林和云杉林的灌木层也很丰富，卫矛属、五加属、茶藨子属、忍冬属植物很丰富，而在白桦林则以栒摘要子属、榛子属、鹅耳枥属等植物为主。藓类植物在云杉林中最丰富，并且形成毯状层，其它两个林分则很稀少。3 个样地林分结构与林下光环境有很强的相关性，从光环境特征可以在一定程度上推测林分的结构。各样地单纯从乔木层材积推算的NPP 排列顺序为BF>FF>SF，与林下辐射透射率和林分年龄的顺序相同，暗示辐射对群落演替过程的驱动作用。 7. 用半球照相法测得BF、FF 和SF 3 个样地的有效叶面积指数以SF 样地最高，BF 最低。如果考虑针叶树叶片在小枝上的丛聚分布，利用北方针叶林的数值进行校正，则SF 样地LAI 显著增加(达到89%)，其它样地的LAI 基本不变甚至有所下降。校正后的数值与文献中地面测量的结果较相近，说明在使用半球照相法测量川西亚高山针叶林LAI 时必须加以校正。 8. 在3 个样地中，白桦、岷江冷杉和方枝柏种群为丛聚分布，紫果云杉在FF和SF 样地中基本上为随机分布。3 个物种出现丛聚分布的最短距离约为2m，在最短距离以内则为随机分布。最短距离可能与树冠大小有关，种子传播特征以及对光照的需求状况可能是造成这种分布格局类型的原因。 Radiative transfer plays a key role in forest ecosystems. Solar radiation providesenergy for photosynthesis, appropriate ambient temperature and development informationfor plants. However, quality and quantity of radiation reaching land surface are affected byweather and subsequently influence the growth and development of plants, which in turnchanges the budget of radiation in forest. Soil temperature changes with the variation ofradiation under forest canopy and influences the activity of roots and rate of nutrientturnover. Thus, any changes of radiation will induce chain reactions in the entireecosystem and display in the value of net primary productivity which will possibly shiftthe relationship between carbon source and sink at local or regional scale and feed back tothe global climate system. On the other hand, as a component of ecosystems, humanbeings of course need to demand more materials and better service from ecosystems. Forthese purpose, man must adapt their pattern and frequency of interference to ecosystems.This paper aims to research on the canopy structure, the radiation distribution and theirinfluence on soil temperature from the process of radiative transfer in subalpine forestecosystem of western Sichuan. The main results are: 1 Present a new photogrammetric method for leaf area. The main idea is to convertnon-vertically taken images of planar leaves to orthoimages through projectivetransformation. The resultant images are used to get leaf morphological parametersthrough image processing. This method enables users to take photos at almost anyorientation and distance if only the leaves are placed on same plane, and to processlarge quantity of leaves in a short time, which is suitable for field measurement. Theresolution of leaf area is adjustable to fit for special requirement. 2 A model using hemispherical photos combining with solar tracks and radiation courseis provided to simulate light variation in forest. The hemispherical photos of canopyrecord the real spatial distribution of each element of plants viewed from a point. Skyradiance is simulated with CIE standard clear sky or cloudy sky model. This modelcan be used to simulate real time light variation under canopy. 3 Present a soil temperature model. Soil could be regarded as a body of resistor andcapacitor. Some of the budget of solar radiation in soil body is transformed into soilpotential energy, the soil temperature. Variation of soil temperature is driven by solarradiation, vegetation, soil properties, etc. This model has two parameters, one of whichis time constant and is related to soil water content. The inversed model can be used tosimulate the variation of soil water. 4 By using model tRAYci developed by Brunner (1998), the 3-D distribution of light inthree subalpine forest stands of Wanglang Nature Reserve has been simulated andvalidated with value of radiometers in these stands. This model can basically satisfythe need for understanding light regimes of these stands. 5 Present some principles and questions of NPP (net primary of productivity) researchesin western Sichuan. The standard leaf area index (LAI) defined by Chen and Black(1997) has not been used in this region. Total leaf area and projected leaf area indexare still used in NPP researches which may differ around 1-fold in magnitude. Thestandard LAI which is a half of total leaf area above unit land area should be between4 and 5 for typical subalpine coniferous forest of western Sichuan concluded fromliteratures. The maximum forest NPP occurs in West China rain belt and decreasesnorthwestwards. Average NPP of spruce-fir forest in western Sichuan is about600gDM m-2 a-1, which is below the potential NPP of 1800gDM m-2 a-1 based onmeasured radiation in this region. The significant difference between potential and realNPP suggests that other factors influence the growth of stands. 6 In the three subalpine forest stands of Wanglang Nature Reserve, herbage layer ofAbstractbirch stand (BF) with age of 40 is dominated by heliophytes of Deyeuxia scabrescens,Origanum vulgare, Aster tongoloa etc.. However, both of the other two stands aredominated by shade tolerent species, such as Impatiens noli-tangere, Impatiensdicentra, Cacalia deltophylla and Pternopetalum tanakae etc. in fir stand (FF) withage of 180 and Fragaria orientalis, Cardamine tangutorum and Oxalis corniculata etc.in spruce stand (SF) with age of 330. Shrub species in the latter two stands arerelatively rich, typical dominant genera being Euonymus, Acanthopanax, Ribes andLonicera. Birch stand has relatively sparse shrubs dominated by genera of Cotoneaster,Corylus and Carpinus. Mosses are significant only in spruce stand. The canopystructure controls the light regime of stand, which influence the composition of herblayers beneath the canopy. This light regime-community structure relationship can beused to infer the herb community from canopy structure. The NPP derived from timbervolume of arbor layer of the three stands decreases from BF to SF, which is in thesame order of transmitted total radiation under canopy and age of these stands,suggesting the driving effect of radiation in the succession of community. 7 The highest effective LAI of the three stands obtained by hemispherical photos is inplot SF and lowest in plot BF. After rectification of the clumping effect of leaves onshoot, the real LAI in plot SF increases significantly (89%) and approximate to theaverage LAI of coniferous forest in western Sichuan. Therefore, the LAI obtainedfrom hemispherical photos needs rectification for clumping effect. 8 Spatial distribution pattern for Betula platyphylla, Abies faxoniana and Sabinasaltuaria is clumpy, but Picea purpurea almost random in plot FF and SF. The shortestdistance for clumpy distribution for Betula platyphylla and Sabina saltuaria is 1.5m,and 2m for Abies faxoniana. And random pattern for these trees is exhibited within thisrange which almost coincides with the diameter of crown. Seed dispersalcharacteristics and light requirement may be the reason for different spatial pattern.

Temperature tolerance of young sporophytes from two populations of Laminaria japonica revealed by chlorophyll fluorescence measurements and short-term growth and survival performances in tank culture

The cold-water subtidal brown alga Laminaria japonica has been commercially fanned in the Far East and has been on top of all marine-fanned species in terms of farming area and annual output worldwide. The successful trials of transplantation of young sporophytes from the north to the south in winter along the Chinese coast in the 1950s led to the spreading of cultivation activities down to a latitude of 25-26 degrees N. Up to today, nearly 50% of the annual output of this farmed alga, as a cold-water species, comes from the sub-tropical south in China. The demand to have high-temperature-tolerant strains/ecotypes in farming area calls for a practical method to judge and select the desired parental plants for breeding programs and for seedling production. In this paper, we report our results on using chlorophyll fluorescence measurement and short-term growth performance in tank culture to estimate the temperature tolerance of offspring from two populations, Fujian Farmed Population (FFP) sampled from Fujian province (latitude: 25-26 degrees N) in subtropical area and Qingdao Wild Population (QWP) sampled from Qingdao (latitude: 36 degrees N). Contrary to what has been usually thought, the results revealed that offspring from Qingdao wild population in the north showed better performance both in short-term growth and survival rates and in optimal quantum efficiency (F-v/F-m) when exposed to higher temperature (20-25 degrees C). This result was further confirmed by fluorescence quenching analysis. QWP distributed along the southern distribution limit at a latitude of 36 degrees N in the Pacific west coast is thus taken as a more ideal one than the fanned population in subtropical region as a source of parental plants for breeding high-temperature-tolerant varieties. (c) 2006 Elsevier B.V. All rights reserved.