Comparative studies on leaf epidermal micromorphology and mesophyll structure of Elaeagnus angustifolia L.in two different regions of desert habitat

In order to obtain qualitative and quantitative characteristics of leaf epidermal micromorphology and mesophyll structure to evaluate the responses ofElaeagnus angustifolia L. to different environmental factors, epidermal micromorphology was observed by scanning electron microscopy （SEM）, and mesophyll structure was studied by light microscopy （LM） and transmission electron microscopy （TEM）. Materials were selected from Linze County, Gansu Province （material A） and Qitai County, Xinjiang Uygur Autonomous Region （material B） of China. Results show that lamina thickness was higher in material A, with one layer of epidermal cells in both adaxial and abaxial surfaces, and epidermal cell radial length was significantly longer in the adaxial surface. E. angustifolia leaves are typically bifacial, with a higher ratio of palisade to spongy tissue in material A. The thickness of trichome layer of epidermis was thicker in material A. In contrast, cell wall and cuticular wax of the epidermal cells were thinner in material A than in material B. Chloroplast ultrastructure was different with the approximate spherical chloroplast containing numerous starch grains and osmiophilic granules in ma- terial A, while only the spindly chloroplast contained starch grains in material B. Multiple layers of peltate or stel- late-peltate trichomes occupied both leaf surfaces in material A and the abaxial surface in material B, while the adaxial surface of material B contained few trichomes. Stomata were not observed on the leaf surfaces in materials A and B by SEM because of trichome obstruction. Our results indicate that the leaf structure of E. angustifolia is closely correlated with environmental factors, and the combination of leaf epidermal micromorphology and mesophyll structure afford re- sistance to environmental stress.

Direct image-based fractal characterization of micromorphology of calcium carbonate fouling crystals

Researches on macroscopic fouling behavior and micromorphology are usually conducted separately.In this paper,the relationship between the macroscopic fouling behavior and micromorphology on different materials is established.A direct fractal-characterization approach based on the micrographs of calcium carbonate fouling crystals is presented.The box-counting method is used to characterize the fouling crystals.For fractal measurements,t-distribution tests of linear regression hypothesis are performed at the significance level of 0.01.If all listed absolute t-statistics with the minimum of 164 are higher than the corresponding t value,the fouling crystals are determined as fractal,with a confidence level of 99%.The fractal dimensions obtained from the micrographs of different visual fields of a specimen are demonstrated to be almost identical,with maximum and minimum relative values of 4.42%and 0.75%,respectively,and standard deviations ranging from 0.0062 to 0.0266.The irregularity of the crystal morphology indicates larger fractal dimensions.Comparison and analysis of the relationship between macroscopic fouling behavior and micromorphology show that the larger fractal dimension of crystal morphology suggests a small amount of surface fouling.Thus,the reasons for the differences in the macroscopic fouling behaviors of different materials are revealed geometrically.

Micromorphology and Quality Attributes of the Loess Derived Soils Affected by Land Use Change:A Case Study in Ghapan Watershed,Northern Iran

In order to study the effects of different land vegetative covers on soil quality attributes, a loess hill slope was selected in eastern Golestan Province, Ghapan watershed, Iran. Four profiles in four land uses, including Quercus natural forest; Pinus artificial forest; Cupressus artificial forest and a cultivated land, were studied. Results showed that MWD was significantly different in the studied land uses, and it varied between 1.6 mm in Quercus natural forest and 0.31 mm in cultivated land use. The lowest CEC, microbial respiration rate and organic carbon were 28.4 cmol·kg-1, 177 μgCO2·g-1·day-1 and 1.32 % found in cultivated land use, respectively. The organic matter content in the forest areas was considerably higher than that of cultivated land use. The studies on soil profile development revealed that the natural forest soils were highly developed. The soils of the Quercus natural forest were classified as Calcic Haploxeralfs with a well developed argillic horizon unlike the cultivated soils which showed the minimum development and classified as Typic Xerorthents. The soils of the artificial forests had both mollic epipedons and were classified as Typic Calcixerolls with moderate profile development. Micromorphological studies revealed that argillic horizons had speckled and partly crystallitic b-fabric in the natural forest indicating the high landscape stability. In contrast, the crystallitic b-fabric of other land uses shows the absence of enough leaching of carbonate and the subsequent migration of clay particles indicating the unstable conditions and high soil erosion. Intense erosion of the surface horizons of cultivated land use has resulted in the outcropping of the subsurface carbonate rich horizons preventing soil development.

Effect of SPM Scanning Range on the Micromorphology Parameters

The surface of a compact disk is analyzed by using SPM and the quantitative micromorphology analysissoftware SPMIAS developed by the author. Images at the same position but with different scanning ranges areobtained under the same experimental conditions. Micromorphology parameters are calculated and compared, andthe relationship between the changing of the scanning range and the changing of micromorphology parameters issummarized.

Integration of SEM/WDX elemental mapping and micromorphology to determine mineralogical traits of peat soils(case study：Northern Iran)

We explored the potential use of combining wavelength-dispersive X-ray spectroscopy(WDX) and micromorphology of thin sections to identify minerals in peat soils. Peat soil minerals from three peats and swamps across Golestan Province in northern Iran were first characterized by micromorphological studies. Soils were composed mainly of quartz, muscovite, biotite, pyroxene,sericitized Fe-nodules, and iron-rich garnet. In addition,micromorphological results indicated that Galougah Coastal Swamp sections contained some inorganic residue with biological origin including oyster and limpet, which may be related to the swamp's location near Gorgan Gulf.In order to determine mineralogical properties of samples,twelve unknown grains were chosen for elemental concentration map studies. Quartz, garnet, ilmenite, calcite,and pyroxene in Suteh samples; epidote and Fe-nodule in Ghaleh-Ghafeh Peat Swamp; and barite, phyllosilicates,and calcite in Galougah were identified by WDX mapping of Si, Al, Fe, Ca, Mg, C, Ba, S, and Ti. Composition of the oysters' body was also analyzed by WDX for Si, Ca, Fe,and C. The results indicated that most of the minerals in all sections likely formed through weathering, inheriting their composition from the parent rock. This research suggests that merging micromorphology and SEM/WDX image techniques can be useful in confirming the presence of mineral particles in soil science.

Development of SPM Quantitative Micromorphology Analysis Software

Scanning Probe Microscope (SPM) has great advantages in quantitative micromorphology analysis because of its conveniencein obtaining micromorphology information of materials on nanometer or atomic scale under control of a computer. Based on an established SPM quantitative micromorphology analysis model, an SPM image analysis software Which can calculate both two- and three-dimensional micromorphology parameters is developed.

Modulations in seed micromorphology reveal signature of adaptive species-diversification in <i>Dendrobium</i>(Orchidaceae)

During speciation in flowering plants, many morphological characters were evolved in response to continuous selection pressure. Such characters are largely governed by genetic changes or get modulated according to ecological adaptations. To explore the potential of latter, a novel comparative analysis of seed micromorphology and ultrastructure was performed in twenty species in the genus Dendrobium (Orchidaceae) from well-defined altitude based phytogeographical realms i.e. temperate, subtropical and tropical regions. Seed morphological characteristics from all collected species were examined using 13 quantitative traits descriptors. Comparative seed morphology revealed that the species from temperate region have larger seed volumes and seed volume/embryo volume ratio than species from subtropical or tropical regions irrespective of their phylogenetic association. Hence, phylogenetically related species emphasized their preference for a climatic region as their prime habitat. Similar trends towards gradual increase of percentage free air space were observed in the species of tropical to subtropical and subtropical to temperate regions. The higher percentage of free air space may have an advantage for the species from temperate region with relatively low atmospheric pressure that had greater buoyancy for optimal seed dispersal. Also, phylogenetically distant species from a particular climatic region, showed characteristic features of the testa cell walls sculptured with bead-like orna-mentations or covered with cottony white substances. Based on these observations, it may be concluded that seed volume, % free air space and seed coat ornamentation in Dendrobium species are signatures of adaptation according to climatic preferences rather than their selection during speciation.

Growth and aggregation micromorphology of natural gas hydrate particles near gas-liquid interface under stirring condition

To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.

郑州市常绿灌木滞留颗粒物能力及季节差异

选取郑州市12种常见常绿阔叶灌木为研究材料,运用3级滤膜法测定叶片对各粒径颗粒物(TSP、PM>10、PM_(10)、PM_(2.5))的滞留量,并通过超景深显微镜和扫描电镜观察比较12种灌木的叶表面微形态结构,分析灌木叶片的滞尘能力、滞尘粒度特征及季节差异。结果表明:1)不同植物的滞尘能力差异显著(P<0.05),火棘和夹竹桃滞留各粒径颗粒物的能力最强,洒金桃叶珊瑚和南天竹最弱。叶片滞留的颗粒物以PM>10为主,其次为PM_(2.5),PM_(2.5~10)的占比最小,在2.52%~15.36%。2)各植物在滞尘粒度特征和滞尘量方面存在季节差异。植物对不同粒径颗粒物的滞留量总体呈现冬季大于春、夏、秋三季的规律,但对PM>10、PM_(2.5)和PM_(2.5~10)的质量占比分别在冬春季、夏季和春季最高。3)叶表面微结构观察表明,叶尖和叶尾是滞留颗粒物的重要部位,而微结构如沟槽、凸起、绒毛、簇状结构等微形态结构则增强了植物的滞尘能力。电镜观察发现,有些植物叶表面具有菌丝,相关分析发现蜡质含量越多则菌丝越多,滞尘能力越强。滞尘树种的筛选应该综合考虑滞尘量、滞尘粒度及季节更替等因素,火棘和夹竹桃对各粒径颗粒物的滞留能力均较强,可以作为郑州市园林绿化中的首选树种。

Cf/C-SiC烧蚀行为及激光复合超声磨削可行性研究

目的揭示激光与Cf/C-SiC陶瓷基复合材料相互作用机理,分析激光能量密度对材料形性演变的影响规律。提出Cf/C-SiC陶瓷基复合材料激光复合超声磨削加工方案,探究硬脆材料多能场复合加工的可行性。方法使用不同能量密度的激光束扫描Cf/C-SiC陶瓷基复合材料表面,以明确材料烧蚀行为。在材料表面预制不同间距的平行纹理沟槽,进而对比传统磨削、超声辅助磨削和激光复合超声磨削的加工效果,同时研究不同扫描间距的预制沟槽对磨削效果的影响规律。结果陶瓷基复合材料(CMC)在激光作用下可呈现2种截然不同的状态,改性状态时材料以氧化等热化学变化为主,样件内出现热影响区和裂纹区。烧蚀状态时材料以热物理和热机械变化为主,样件内出现烧蚀凹坑、重铸层、热影响区和裂纹区。纤维束中界面经整体脱黏后,裂纹向下延伸并发生偏转。基体中的裂纹多起源于纤维界面处,并在扩展过程中发生偏转、分叉。激光烧蚀作用可改变材料的可加工性,有利于后续超声磨削加工。激光复合超声磨削的两方向磨削力相较传统磨削分别减小了51.4%和56.5%,同时表面粗糙度Sa可降低至4.228μm。结论激光复合超声磨削可有效降低磨削力和加工表面粗糙度,从而提高加工质量,该方法在实现硬脆材料高质量低成本加工方面具有较大的潜能。

课程思政融入材料类专业夏季学期实践的教学探索

将课程思政融入实践教学环节是高等学校贯彻价值塑造、知识传授和能力培养“三位一体”育人理念、落实立德树人根本任务的重要途径。该文以天津大学材料科学与工程学院“走进材料微观世界”夏季学期实践课程思政建设情况为例,从夏季学期实践教学现状和课程思政建设必要性、课程思政改革途径、课程思政元素的挖掘与融入三个方面进行阐述分析,旨在为材料类专业实践教学课程思政建设提供思路,推进全过程、全方位协同育人。

反式聚异戊二烯/有机黏土复合材料的形状记忆性能

以反式聚异戊二烯(TPI)为基体,通过加入有机黏土(OC)制备了TPI/OC纳米复合材料(TPICNs)。通过X射线衍射、差示扫描量热、动态力学分析和扫描电子显微镜等手段分别考察了TPICNs的结晶情况、形状记忆性能、力学性能和微观形貌。结果表明,随着OC用量的增加,TPICNs的结晶度、拉伸强度和形状回复率均先增大后减小;当OC用量为1.2份(质量)时,TPICNs的拉伸强度最大且展现出最好的形状记忆行为;TPICNs断面处结晶颗粒分布均匀。

防爆柴油机排气颗粒物的微观结构研究

为研究废气水洗箱和含氧燃料对防爆柴油机排气颗粒物微观结构随工况变化的影响,利用扫描电子显微镜(Scananing Elecron Microscope,SEM)对0#柴油(D100)和丁醇/柴油混合燃料(BD20)的排气颗粒物的微观形貌、分形特征和粒径分布进行研究。其中,丁醇的质量分数为20%。结果显示:经过废气水洗箱后,颗粒物内吸附质含量增多,密集程度升高,在多数工况下,颗粒物支链减少,且BD20有利于减少颗粒物碳烟粒子含量;颗粒物的计盒维数分布在1.70~1.85,且经过废气水洗箱的颗粒物结构更紧密,计盒维数更大,D100的计盒维数大于BD20的计盒维数;颗粒物基础碳粒子粒径分布在10~90 nm,废气水洗箱对颗粒物有沉降作用,使颗粒物平均粒径减小,BD20的平均粒径小于D100平均粒径。

中国杨属叶表皮毛状体微形态特征

为讨论叶表皮毛状体特征的分类学价值和系统学意义,借助体视显微镜和扫描电镜对中国杨属(Populus)33个物种的叶表皮毛状体进行了观察和分析。结果表明:杨属物种叶片毛状体整体上是非腺状的、简单的、基底固定的;除胡杨(P.euphratica)叶表皮没有毛状体外,其余物种叶表皮均被有毛状体,但毛状体的分布、形态、长度等在物种间存在不同程度差异。毛状体外形(圆柱状至条带状)、弯曲程度(直立至曲卷)、相对于叶表皮表面的方向(伏贴或不伏贴)及毛状体长度具有一定的分类学意义。结合分子系统发育研究提供的进化框架,本研究认为杨属叶表皮毛状体特征在亚属水平难以区分,但胡杨亚属(subg.Turanga)和白杨亚属(subg.Populus)在种间水平可区分很多物种,尤其是白杨亚属内的物种毛状体差异大;脂杨亚属(subg.Tacamahaca)内叶片毛状体相似且稳定,但不同分支上的叶片毛状体在长度上有差异。毛状体特征整合后可划分为以下类型:无毛、毡毛、绢毛、短柔毛和长柔毛。

基于形态学性状的洪平杏与近缘种种间关系研究

本研究通过野外调查获得洪平杏(Armeniaca hongpingensis T.T.Yu&C.L.Li)、杏(A.vulgaris Lam.)、梅(A.mume Siebold)和杏梅(A.mume var.bungo Makino)有关的叶、花、果、果核及枝条的21个定量性状和15个定性性状,并对这些数据进行了聚类分析。结果显示,无论是PAM聚类还是UPGMA聚类分析都可清晰地将4种杏属植物分开,说明物种之间具有明显的区分特征。主成分分析的前3个主成分中,一年生枝颜色、被毛情况,叶及果实被毛,叶形指标(叶形、叶尖、叶基)和果核表面特征的绝对权重值都在0.9以上,表明这些性状在4种杏属植物的分类中具有重要的作用。电镜扫描观察结果发现,供试花粉均是单粒花粉,等极,辐射对称,具3孔萌发沟。杏、梅、杏梅的花粉表面纹饰均为条纹状,但洪平杏的表面纹饰为间断条纹,且有不明显穿孔。4种植物叶上表皮细胞均具条纹状角质增厚。与其他种相比,洪平杏细胞表面条纹常弯曲、交叠,无固定走向。根据聚类分析结果和微形态特征,支持将洪平杏作为区别于梅和杏的一个独立种的处理。

两种大豆籽粒萌发特性差异的比较转录组分析

大豆种子的萌发决定着幼苗建成和生长发育进程,快速萌发及高发芽率是大豆生产中获得高产的重要保障。本研究以不同萌发特性的黑农35及其诱变株系M为材料,基于萌发初期种皮微形态观察和主要生理指标检测,拟通过“露白期”(吸水后24 h)转录组的差异基因分析,进一步明晰大豆种子萌发机理。结果表明,两者的吸水率和发芽率存在显著差异;扫描电镜观察发现,与黑农35相比,M的种脐较长,种皮较薄,这些形态特征可能是萌发初期M吸水更快的主要原因。萌发过程中脱落酸(ABA)含量逐渐下降,可溶性蛋白含量均呈先下降后上升趋势,可溶性糖含量均为上升-下降-上升的“S”形。转录组分析发现两者共有1122个差异基因,其中478个上调,644个下调,差异基因主要富集在光合作用途径,筛选到22个与光合途径相关的候选基因,在M中均呈下调趋势,可能引起光形态建成较慢,进而导致诱变株系M萌发率变低,研究结果可为解析大豆种子萌发的调控机制提供思路。

响应面法优化花生水酶法制油水相体系中残油工艺

水酶法可以实现花生油脂和蛋白的同步提取,但得到的水相体系中部分油脂稳定存在,不利于油脂得率的提升。通过湿法粉碎花生,利用激光共聚焦显微镜(CLSM)和生物显微镜对花生水酶法制油水相体系的微观形态进行观察,分析不同粉碎时间下水相残油率和油滴分布之间的联系。在单因素试验基础上,采用响应面法优化影响水相残油率的工艺条件。结果表明:花生水酶法制油得到的水相是一个高蛋白低油脂的体系,当粉碎时间为120 s时,水相残油率最低(10.78%),水相体系油滴分布最少;最佳工艺条件为酶解时间1.37 h、酶解温度47.92℃、加酶量1.25%、液料比4.89∶1 mL/g,在此条件下得到的水相残油率为8.79%±0.03%,与响应面预测值8.82%无显著性差异。研究结果为间接提高水酶法制油提升油脂得率提供理论依据。

单向CF/PA6复合材料性能劣化及老化寿命预测

利用热压成型工艺制备出碳纤维(CF)/尼龙6(PA6)复合材料单向板,并将复合材料试样置于蒸馏水热水浴中,分别在25,60,80℃下进行不同时间的湿热老化,再对湿热老化后复合材料试样进行吸湿测试、三点弯曲测试、微观形貌表征,探究复合材料的吸湿规律、力学性能劣化规律和微观形貌变化,并对复合材料的长期寿命进行预测。结果发现,复合材料在25,60℃下的吸湿行为基本符合Fick扩散定律,而80℃下在老化最后阶段出现了背离Fick扩散定律现象。复合材料的弯曲强度随老化温度、老化时间的增加呈下降趋势,分别在25,60,80℃下老化120 d后,试样弯曲强度分别下降了22.78%,25.0%,26.25%。但是老化温度、老化时间对弯曲弹性模量无显著影响,且CF与PA6树脂之间的界面黏合性能随着温度、时间的增加逐渐变差。以绍兴2021年平均温度作为服役温度,基于加速老化测试模型和阿伦尼乌斯理论建立了CF/PA6复合材料在服役环境下剩余弯曲强度的预测模型,可预测到1 400 d后,CF/PA6复合材料的弯曲强度保留率在64.8%左右。

基于物方差动共焦轴向测量引导的显微镜自动对焦方法

针对传统自动聚焦方法效率低,难以适应工业产品微观形貌检测高精度、高效率需求的问题,提出一种基于物方差动共焦轴向测量引导的显微镜自动对焦方法(DCAFM)。在获取测量系统中离焦量和轴向光强差之间的标定曲线后,控制运动机构使物镜与样本的轴向距离以等步距的方式采集图像。通过焦前与焦后位置光强差快速确定当前轴向离焦量,控制轴向运动机构,实现快速自动对焦。搭建显微镜自动对焦实验平台,对样品进行测试。实验结果表明:文中方法的图像对焦速度和灵敏度优于DFT,EOG等自动对焦方法,系统的轴向分辨率优于0.4μm,有效地提高了显微镜的对焦速度和精度。

磨料水射流切削皮质骨断面形貌特征研究

为探索磨料水射流切削过程中对皮质骨材料的切削机理,提高切削断面质量,分别以石榴石、氯化钠为磨料对皮质骨进行切削,对比不同切削方向下断面粗糙度变化规律以及微观划痕特征.实验结果表明,断面粗糙度数值均呈现先减小后增大的特点,依据表面粗糙度数值将断面分为初始区、光滑区、粗糙区3部分.当使用磨料为氯化钠,切削方向垂直于骨单元时,断面粗糙度平均值分别是切削方向平行和横向于骨单元时断面粗糙度平均值的1.74倍和1.70倍.当使用磨料为石榴石,切削方向垂直于骨单元时,断面粗糙度平均值分别是切削方向平行和横向于骨单元时断面粗糙度平均值的1.41倍和1.55倍.切削过程中断面形成大量微米级划痕,对比氯化钠、石榴石2种磨料对断面划痕特征的影响,与石榴石相比,当使用磨料为氯化钠时,皮质骨切削断面划痕尺寸偏大,长度、宽度值跨度相近,划痕深度值跨度较大.