中国合叶苔科（苔纲）植物的研究

合叶苔科Scapaniaceae隶属于苔纲Hepaticae叶苔目Jungermanniales，全世界约6属136个现存种，1个化石种。合叶苔科的科和属的特征明显，但物种间变化大，分类比较困难，部分属种的分类位置亦存在争议。本研究前，中国已记录合叶苔科植物有4属，66种3变种，其中9种1变种已归为同物异名，承认的种类共57种2变种。以中国产标本为基础发表的新分类单位共2属16种2变种。目前尚无专门针对中国合叶苔科的系统研究，因此，开展中国合叶苔科的分类、区系和生态研究，对深入认识中国苔类植物多样性、区系和系统具有重要的科学意义。 本研究运用植物学经典分类的基本方法和现代的分支系统分析方法，对国内、外主要苔藓植物标本馆的中国合叶苔科植物的模式标本和有关标本进行了较全面的检查和详细的形态解剖和分类学研究，并开展了野外补充调查采集，完成了对中国合叶苔科植物的分类修订，分析该科的区系成分组成和在中国的地理分布特点及其属种之间的分支系统关系。研究的主要结果如下： （1）在相关模式标本和国内外标本鉴定和研究的基础上，确认中国合叶苔科有3属52种1变种，包括：大褶叶苔属Macrodiplophyllum1种，褶叶苔属Diplophyllum5种，合叶苔属Scapania46种1变种。发现并发表新种2个，即片毛合叶苔S. macroparaphyllia T. Cao, C. Gao & J. Sun（曹同等，2004）和毛茎合叶苔S. paraphyllia T. Cao, C. Gao, J. Sun et B. R. Zuo（Zuo et al., 2007）；发现中国新分布记录2种，尖瓣合叶苔S. ampliata Steph.（Zuo & Cao, 2007）和扁平合叶苔S. compacta (Roth) Dum.(首次报道，尚未发表)。完成了对中国合叶苔科植物的分类修订，对每个属、种都进行了文献考证、特征描述、图版绘制和分类讨论，并利用Mapinfo软件绘制了各种在中国的分布图。 （2）对相关模式标本标定和研究，澄清了一些分类问题和中国种的概念。如对东亚分布的若干种类进行了比较和评估，划定其分类界限，确认2种已经被归并为弯瓣合叶苔S. parvitexta Steph.新异名的种类仍然为独立的种，即细齿合叶苔S. parvidens Steph.和灰绿合叶苔S. glaucoviridis Horik.。并对东亚特有属种侧囊苔属的侧囊苔Delavayella serrata Steph.进行了模式标定，探讨了它的地理分布和系统位置，支持将其独立成侧囊苔科Delavayellaceae的观点。 （3）在标本鉴定和野外采集工作的基础上，合叶苔科各种在中国的分布范围大为增加，为开展中国合叶苔科的地理分布格局奠定了基础。对现有的地理分布资料的分析表明，西南地区（西藏，云南，四川，贵州）是中国的合叶苔属植物的分布中心和可能的起源中心，共有合叶苔40种，占该属总数（46种）的86.96%，其中，15种仅分布在西南地区，中国特产9种中，有8种在西南地区分布。此外，东北地区、华东地区及台湾省分布种类较多，分别为16种（34.78%），22种（47.83%）和17种（36.96%）种的分布。 （4）区系成分分析结果表明，合叶苔属Scapania主要由2大区系成分组成：东亚成分25种，占总数的51%，其中，中国-日本分布7种，中国-喜马拉雅分布9种，中国特产种9种。北温带成分22种，占总数的45%，其中有18种在亚洲，欧洲和北美洲均有分布。褶叶苔属Diplophyllum 5种，4种为北温带成分，1种为中国-日本分布的东亚成分。分析结果反映了中国苔藓植物区系的基本特点，即与欧美植物区系有密切联系，同时又体现了较强的东亚区系特色。 （5）对合叶苔属Scapania植物的生态和生境分析表明，47个分类群可分成3种主要类型：1）沼泽或水湿生；2）以腐木生为主，有时生于岩面薄土上的小型种类；3）潮湿岩面或林下土生的中等和大型种类。 （6）选取了39个反映系统发育关系的形态特征，以与合叶苔科相近的裂叶苔科Lophoziaceae中挺叶苔属Anastrophyllum 2种和裂叶苔属Lophozia 1种为外类群，运用外类群比较法对合叶苔科的的属种之间的演化关系进行了分支系统分析。结果表明，原归于合叶苔科的侧囊苔属Dalevayella为单独的一个分支，应为独立的侧囊苔科Dalevayellaceae。大褶叶苔属Macrodiplophyllum和褶叶苔属Diplophyllum植物相近，可归并为一个属，与合叶苔属Scapania同为合叶苔科Scapaniaceae下的属。中国合叶苔属47个分类群可分为若干组，主要与其生境，植物体，叶的结构，无性繁殖等特征有关，结果与目前采用的合叶苔科的分类系统与演化关系基本一致。

山西省的淡水红藻

报道山西省的淡水红藻植物,共计有15种,隶属于6目,7科,9属,即紫球藻Porphyridiumpurpureum Bory DrewetRoss,暗紫红毛菜Bangiaatropurpurea Roth Agardh,细弱弯枝藻CompsopogontenellusLingetXie,弯枝藻C.coeruleus BalbisexC.Agardh Montagne,灌木状拟弯枝藻Copsopogonopsisfruticosa Jao Seto,异孢奥杜藻AudouinellaheterosporaXieetLing,硬枝奥杜藻A.chalybea Roth Bory,矮小奥杜藻A.pygmaea Kützing Weber-vanBosse,棘刺红索藻Thoreahispida Thore Desvaux,鸭形串珠藻Batrachospermumanat-inumSirodot,胶串珠藻B.gelatinosum Linnaeus DeCandolle,弧形串珠藻B.arcuatumKylin,绞扭串珠藻B.in-tortumJao,细连珠藻Sirodotiatenuissima Collins SkujaexFlint和胭脂藻Hildenbrandiarivularis Leibmann Agardh.

Facile preparation of macroscopic soft colloidal crystals with fiber symmetry

A facile, efficient way to fabricate macroscopic soft colloidal crystals with fiber symmetry by drying a latex dispersion in a tube is presented. A transparent, stable colloidal crystal was obtained from a 25 wt % latex dispersion by complete water evaporation for 4 days. The centimeter-long sample was investigated by means of synchrotron small-angle X-ray diffraction (SAXD). Analysis of a large number of distinct Bragg peaks reveals that uniaxially oriented colloidal crystals with face-centered cubic lattice structure were formed.

Effect of annealing on the deformation mechanism of a styrene/n-butyl acrylate copolymer latex film investigated by synchrotron small-angle X-ray scattering

The deformation mechanism of a styrene/n-butyl acrylate copolymer latex film subjected to uniaxial tensile stress was studied by small-angle X-ray scattering. The influence of annealing at 23, 60, 80, and 100 degrees C for 4 h on microscopic deformation processes was elucidated. It was demonstrated that the microscopic deformation mechanism of the latex films transformed gradually from nonaffine deformation behavior to affine deformation behavior with increasing annealing temperature.

Structural evolution of tensile deformed high-density polyethylene at elevated temperatures: Scanning synchrotron small- and wide-angle X-ray scattering studies

The structural evolution of an ice-quenched high-density polyethylene (HDPE) subjected to uniaxial tensile deformation at elevated temperatures was examined as a function of the imposed strains by means of combined synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. The data show that when stretching an isotropic sample with the spherulitic structure, intralamellar slipping of crystalline blocks was activated at small deformations, followed by a stress-induced fragmentation and recrystallization process yielding lamellar crystallites with their normal parallel to the stretching direction. Stretching of an isothermally crystallized HDPE sample at 120 degrees C exhibited changes of the SAXS diagram with strain similar to that observed for quenched HDPE elongated at room temperature, implying that the thermal stability of the crystal blocks composing the lamellae is only dependent on the crystallization temperature.

In Situ Observation of Tensile Deformation Processes of Soft Colloidal Crystalline Latex Fibers

The deformation mechanism or styrene/n-butyl acrylate copolymer latex films with fiber symmetric crystalline structure subjected to uniaxial stretching was studied using synchrotron small-angle X-ray scattering technique. The fibers were drawn at angles or 0, 35, and 55 degrees with respect to the Fiber axis. In all cases, the microscopic deformation within the crystallites was Found to deviate from affine deformation behavior with respect to the macroscopic deformation ratio. Moreover, the extent of this deviation is different in the three cases. This peculiar behavior can be attributed to the relative orientation of the (111) plane of the crystals, the plane of densest packing, with respect to the stretching direction in each case. When the stretching direction coincides with the crystallographic (111) plane, which is the case for stretching directions of 0 and 55 degrees with respect to the fiber axis, the microscopic deformation deviates less from affine behavior than when the stretching direction is arbitrarily oriented with respect to the crystallographic (111) plan.

GIUSAXS and AFM Studies on Surface Reconstruction of Latex Thin Films during Thermal Treatment

The structural evolution of a single-layer latex film during annealing was studied via grazing incidence ultrasmall-angle X-ray scattering (GIUSAXS) and atomic force microscopy (AFM). The latex particles were composed of a low-T-g (-54 degrees C) core (n-butylacrylate, 30 wt %) and a high-T-g (41 degrees C) shell (t-butylacrylate, 70 wt %) and had an overall diameter of about 500 nm. GIUSAXS data indicate that the q(y) scan at q(z) = 0.27 nm(-1) (out-of-plane scan) contains information about both the structure factor and the form factor. The GIUSAXS data on latex films annealed at various temperatures ranging from room temperature to 140 degrees C indicate that the structure of the latex thin film beneath the surface changed significantly. The evolution of the out-of-plane scan plot reveals the surface reconstruction of the film. Furthermore, we also followed the time-dependent behavior of structural evolution when the latex film was annealed at a relatively low temperature (60 degrees C) where restructuring within the film can be followed that cannot be detected by AFM, which detects only surface morphology.

Uniaxial deformation of overstretched polyethylene: In-situ synchrotron small angle X-ray scattering study

Synchrotron small angle X-ray scattering was used to study the deformation mechanism of high-density polyethylene that was stretched beyond the natural draw ratio. New insight into the cooperative deformational behavior being mediated via slippage of micro-fibrils was gained. The scattering data confirm on the one hand the model proposed by Peterlin on the static structure of oriented polyethylene being composed of oriented fibrils, which are built by bundles of micro-fibrils. On the other hand it was found that deformation is mediated by the slippage of the micro-fibrils and not the slippage of the fibrils. In the micro-fibrils, the polymer chains are highly oriented both in the crystalline and in the amorphous regions. When stretching beyond the natural draw ratio mainly slippage of micro-fibrils past each other takes place. The thickness of the interlamellar amorphous layers increases only slightly. The coupling force between micro-fibrils increases during stretching due to inter-microfibrillar polymer segments being stretched taut thus increasingly impeding further sliding of the micro-fibrils leading finally to slippage of the fibrils.

Structural evolution of tensile-deformed high-density polyethylene during annealing: Scanning synchrotron small-angle X-ray scattering study

The structural evolution of high-density polyethylene subjected to uniaxial tensile deformation was investigated as a function of strain and after annealing at different temperatures using a scanning synchrotron small-angle X-ray scattering (SAXS) technique. The results confirm that in the course of tensile deformation intralamellar block slips were activated at small deformations followed by a stress-induced fragmentation and recrystallization process yielding thinner lamellae with their normal parallel to the stretching direction. The original sheared lamellae underwent severe internal deformation so that they were even less stable than the newly developed thinner lamellae. Accordingly, annealing results in a melting of the original crystallites even at moderate strains where the stress-induced fragmentation and recrystallization just sets in and generates a distinctly different form of lamellar stacks aligned along the drawing direction. It was found that the lamellae newly formed during stretching at moderate strains remain stable at lower temperature. Only at a very high annealing temperature of 120 degrees C can they be melted, leading to an isotropic distribution of the lamellar structure.

Non-affine structural evolution of soft colloidal crystalline latex films under stretching as observed via synchrotron X-ray scattering

A polymer dispersion consisting of soft latex spheres with a diameter of 135 nm was used to produce a crystalline film with face-centered cubic (fcc) packing of the spheres. Different from conventional small-molecule and hardsphere colloidal crystals, the crystalline latex film in the present case is soft (i.e., easily deformable). The structural evolution of this soft colloidal latex film under stretching was investigated by in-situ synchrotron ultra-small-angle X-ray scattering. The film exhibits polycrystalline scattering behavior corresponding to fcc structure. Stretching results not only in a large deformation of the crystallographic structure but also in considerable nonaffine deformation at high draw ratios. The unexpected nonaffine deformation was attributed to slippage between rows of particles and crystalline grain boundaries. The crystalline structure remains intact even at high deformation, suggesting that directional anisotropic colloidal crystallites can be easily produced.

Early development of germlings of Sargassum thunbergii (Fucales, Phaeophyta) under laboratory conditions

Morphology and culture studies on germlings of Sargassum thunbergii (Mertens et Roth) Kuntze were carried out under controlled laboratory conditions. Growth characteristics of these germlings grown under different temperatures (from 10 to 25A degrees C), irradiances (from 9 to 88 mu mol photons m(-2) s(-1)), and under blue and white light conditions are described. The development of embryonic germlings follows the classic "8 nuclei 1 egg" type described for Sargassaceae. Fertilized eggs spent 5-6 h developing into multicellular germlings with abundant rhizoids after fertilization. Under conditions of 20A degrees C, 44 mu mol photons m(-2) s(-1) and photoperiod of 12 h, young germlings with one or two leaflets reached 2-3 mm in length after 8 weeks. Temperature variations (10, 15, 20, 25A degrees C) under 88 mu mol photons m(-2) s(-1) significantly influenced the growth rate within the first week, although this effect became less obvious after 8 weeks, especially at 15 and 20A degrees C. Variation in germling growth was highly significant under different irradiances (9, 18, 44, 88 mu mol photons m(-2) s(-1)) at 25A degrees C. Low temperature (10A degrees C) reduced germling growth. Growth of germlings cultured under blue light was lower than in white light. Optimal growth of these germlings occurred at 25A degrees C and 44 mu mol photons m(-2) s(-1).