Phase transitions, micro-morphology and its oxidation mechanism in oxidation of ilmenite (FeTiO_3) powder

Phase transitions, morphology changes, and oxidation mechanism of the ilmenite oxidation process were investigated. FeTi03 transforms to hematite and rutile when oxidation at 700-800 ℃, and pseudobrookite is formed when the oxidation temperature reaches 900 ℃. The initial ilmenite powder exhibits paramagnetism; however, after being oxidized at the intermediate temperature （800-850 ℃）, the oxidation product exhibits weak ferromagnetism. The oxidation mechanism was discussed. The microstructure observations show that a lot of micro-pores emerge on the surfaces of ilmenite particles at the intermediate temperature, which is deemed to be caoable ofenhancin~ the mass transfer ofoxgen during oxidation.

Leaf Micro-Morphology in Two Ecotypes of Ashleaf Maple Adaptated to Different Survival Environments

Through one hundred years of adaptation in China, The Acer negundo Linn. (as hlea f maple), originally grown in North America, has developed morphological charact er istics to cope the severe situation of its habitats. Two ecotypes from different vegetation belts in the ecotone of eastern Inner Mongolia Autonomous Region wer e detected. Although there was no macroscopic difference, contrasting micro-ch a racteristics had been observed between the two sources. The leaves from more dro ught and warmer zone were found with more trichomes, more and smaller stomata, l arger subsidiary cells, thicker palisade and flatter epidermal wax than those of leaves from the more humid and colder zone. Microstructures of the leaves from xeric sources can more effectively reduce leaf temperature and conserving water than those of mesic sources. Intra-species difference of the two ecotypes is th e result of adaptation in different environments. This should be considered when characteristics of foliage are used as characters of species in taxonomy.

The Characteristics of Quartz Micro-morphology of The Fault Gouge in Bailongjiang Fault System and Its Chronology

A great deal of important information referring to fault motion (such as fault activities period, intensity, frequency, and even dynamic background, etc.) can be revealed by resolving fault gouge, which are the special result of fault motion while extruding or grinding. Based on the field investigation, collected from Bailongjiang fault system of Western Qinling Orogenic (QO) Belt, 44 samples of fault gouge were for quartz micro-morphology observation and statistics by the field emission SEM, and 14 samples were tested by thermo-luminescence dating. The results showed that most of the micro-morphology of quartz grains are fish scale and orange-haut fractures, but a small amount of moss-like, stalactitic, and subconchoidal fractures. Also very few decay of quartz grains and typical conchoids fracture quartz grains can be seen. This implied that the Bailongjiang fault system was motioned repeatedly in Quaternary period but main motion period was Pleistocene. 14 thermo-luminescence dating values showed herewith two groups as 343.29-184.06 ka and 92.18-13.87 ka. Therefore, the conclusions can be reached that the fault system were motioned starting at Pliocene epoch, frequently in the middle of Pleistocene (343.29-184.06 ka), and peak frequency in late Pleistocene (92.18-13.87 ka). The fault system motions have stopped at Holocene. The results are significant for the natural disaster risk evaluation in western QO region.

Effect of substrate micro-morphology on heterogeneous nucleation

The heterogeneous nucleation process of NH4Cl crystals from a NH4Cl-70wt.%H2O solution on rough chilling substrates was considered in this paper. Scratched and etched substrates of aluminum were prepared with different surface morphologies. It was concluded that for nucleation to occur on a rough substrate surface, the wettability or the generally said roughness are not the key factors affecting the heterogeneous nucleation process. Rather the surface morphologies on the nanometer scale, which is close to the scale of the critical nucleation radius, are more important.

Effects of Long-term Fertilization on Micro-morphological Features in Purple Soil

[Objective] The study aimed to better understand the effect of different fertilizer treatments on micro-morphological characteristics of a purple soil at the 0-20 cm topsoil in a long-term fertilizer experiment. [Method] Soil micro-morphology was observed and analyzed under a single polarizing microscope. [Result] For the CK （no fertilizer） treatment, soil structure was dense with little porosity developed. Its soil microstructure was poor, sandy fabric-granular fabric. After continuously applied chemical fertilizers only for more than two decades, the soil particles did not evolve into soil structures and formed little porosity. The microstructures of soil in N, NP and NPK treatments were porphyroskelic fabric-fine sandy granular fabric, better than that of the soil in CK treatment. Adding manure obviously improved the quantity of groundmass and endowed the soil a loose structure and plenty porosity, enriched animal and plant residues, and well-formed iron-manganese nodules and humus ma- terials, all resulting in better micro-aggregates development. The type of soil microstructures in MNPK treatment was pectized-compacted takyric fabric-intertextic fabric, the best among all the treatments. [Conclusion] Combined application of both or- ganic and inorganic fertilizers can significantly improve the structure of the purple soil, enhance soil fertility and achieve soil sustainable development.

Micro-morphological Features of Topsoil under Long-term Cultivation of Grain and Cotton Crops in Northwestern Shandong

This study aimed to provide a basis for the rational improvement of the microstructure of the soil that had been planted with crops for a long time. Conventional and micro-morphological methods were used to study the effects of planting grain and cotton crops on soil properties in Gaotang County,Shandong Province. The results showed that long-term cultivation of grain and cotton crops has a significant impact on soil micro-structure. The top soil( 0-10 cm) of wheat-maize field has higher organic matter content,uniform aggregate size,high separation,and strong packing void connectivity,forming a type micro-structure that is conducive to agricultural production. The characteristics of soil matrix are mainly inherited from soil parent materials,and the impact of crop cultivation on soil matrix is very weak. The amount of formations in the soil is less,and only Fe nodules,Mn nodules and excrement are observed.

Biodiversity of the Micro-morphologies of the Petal Epidermis of Angiosperms &Their Scientific Aesthetics, Quasi-Geometry

The micro-morphologies and biodiversities of the epidermis of flower petals of angiosperms were reported for the first time. By manual slicing anatomy and microscopic photography technique, the micro-morphologies of the upper and lower epidermis of petals of some common ornamental flowers in Kunming were studied, and the biodiversities were discovered. The results showed these much-varied pigment cells appeared not only a new compensation to anatomy, but a new criteria to taxonomy, so that a brand new research field of “Cell Taxonomy” was established instead of the current “Chromosome Taxonomy” widely used in phytosystematics research. Furthermore, the most interesting and significant phenomena was their scientific aesthetics: these pigment cells of flower petals were quite special, planary, far different from the ordinary plant cells in plant organs & tissues. By comparison to ordinary geometry, these colorful cells of the fresh flower petals could be described as “Quasi-geometry” for their special origin and micro-morphological characteristics. As for the aspect of art, it was quite similar to “Quasi-crystal” discovered by Daniel Schechtman, so that the art future was discussed, obviously another new epoch of scientific-art history began.

Intrafloral differentiation of stamens in heterantherous flowers

Flowers that have heteromorphic stamens （heterantherous flowers） have intrigued many researchers ever since the phenomenon was discovered in the 19th century. The morphological differentiation in androecia has been suggested as a reflection of ＂labor division＂ in pollination in which one type of stamens attracts pollinators and satisfies their demand for pollen as food and the other satisfies the plant＇s need for safe gamete dispersal. The extent and patterns of stamen differentiation differ notably among taxa with heterantherous flowers. Seven species with heteromorphic stamens in three genera were sampled from Leguminosae and Melastomataceae, and the morphological difference of androecia, pollen content, pollen histochemistry and viability, pollen micro- morphology, as well as the main pollinators were examined and compared. Pollen number differs significantly between stamen sets of the same flower in most species investigated, and a correlation of pollen number and anther size was substantiated. Higher pollen viabilities were found in the long （pollinating） stamens of Senna alata （L.） Roxb. and S. bicapsularis （L.） Roxb. Dimorphic pollen exine ornamentation is reported here for the first time in Fordiophytonfaberi Stapf. The height of stigma and anther tips of the long stamens in natural conditions was proved to be highly correlated, supporting the hypothesis that they contact similar areas of the pollinator＇s body.

Fractal Characteristics of Stagnic Anthrosols and the Relationship with Soil Micro-Structure

The Stagnic Anthrosols developed from quaternary yellow sedimentary parent material occupied an important position in Southwest China. Fractal dimensions of particle size and micro-aggregate size distributions of Stagnie Anthrosols and their relationship to soil micro-structure had been probed. Results showed that the soil particle size distributions were dominated by clay, the fractal dimensions of particle size distributions （Ds） were high and between 2.676-2.925, as the fractal dimensions of micro-aggregate size distributions （Da） were between 2.354-2.853. The fractal dimensions of particlesize distributions were preferably related with the ratio of coarse particles and fine particles （c/f20 ,m） and the micromorphological feature of skeleton grains. The evolution degree of micro-structure among horizons were reflected by the coefficient of variation of Ds within the profile. The fractal dimensions of micro-aggregate size distributions were related with the quantities, distributions of micro-aggregates and micro-pores. Results revealed that the soil micro-structures could be quantified by fractal dimensions preliminarily.

Comparative Foliar Structure of Vicia L. Species from China

The genus Vicia L. includes about 190 species around the world and approximately 40 species in China. The genus includes minor food crops and forage plants. This study gives a detailed description of foliar structure of some Vicia species from China. Leaf characters showed considerable variation among studied taxa including petiole and tendril length;leaflets number, length, width, shape, apex, base;blade surface, trichome shape, type, base and length;stipules shape, base, length, width and surface. Numerical analysis of these characters was used to construct a phenogram illustrating the relationship between the studied taxa and to build an artificial key to identify Vicia species. Moreover, variation in leaf characters helped in overcoming the overlapping among harmful taxa.

Crepis desertorum(Asteraceae,Cichorieae),a new species from northern Xinjiang(China)based on morphological and molecular data

Crepis desertorum from the Junggar Basin of no rthern Xinjiang,northwestern China,is described as a new species.Molecular studies indicate that the species is closely related to Crepis frigida.Morphological studies indicate that it is similar to Crepis sancta subsp.bifida but differs from the latter taxon in having glandular hairs on the stem,a flat receptacle and dimorphic achenes.Chromosome features and pollen and achene ultrastructure also are described for the new species.

Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

Polyimide （PI） film is an important type of insulating material used in inverter-fed motors. Partial discharge （PD） under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage （BCSIV） is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage （PDIV）. The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy （FTIR） and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy （SEM）. The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond （C-O-C） and imide ring （C-N-C） on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant e to increase and dielectric loss tan ~ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI oolvmer bulk.

Effects of Fiber Distribution and Content on Performance of Engineered Cementitious Composite (ECC)

The 21 dog-bone specimens with different fiber contents and fiber distribution (random chopped fiber or directional continuous filament fiber bundles) were designed and tested under uniaxial tension using domestic PVA (polyvinyl alcohol) fiber.High fiber content exerted positive influences on cracking stress,peak stress and deformation capacity of specimens with random chopped fiber,compared with the decrease shown in cracking stress of specimens containing directional fiber bundles.There were multiple cracks in specimens containing directional fiber bundles,while only 1-2 typical cracks could be shown in chopped fiber specimens after being broken.Random chopped fiber connected more closely with matrix compared with that only part of fiber bundles could contact with matrix.Double-fold line model and parabolic model could be used simultaneously to fit well with the uniaxial tension constitutive relations of engineered cementitious composite (ECC).Although the performance of PVA produced in China can not reach to the same level of those from Japan,there exists certain practical value in engineering according to its contribution to deformability of structure.

Analysis of Wear Mechanism and Influence Factors of Drum Segment of Hot Rolling Coiler

Because the work environment of segment is complex, and the wear failures usually happen, the wear mechanism corresponding to the load is a key factor for the solution of this problem. At present, many researchers have investigated the failure of segment, but have not taken into account the compositive influences of matching and coiling process. To investigate the wear failure of the drum segment of the hot rolling coiler, the MMU-5G abrasion tester is applied to simulate the wear behavior under different temperatures, different loads and different stages, and the friction coefficients and wear rates are acquired. Scanning electron microscopy（SEM） is used to observe the micro-morphology of worn surface, X-ray energy dispersive spectroscopy（EDS） is used to analyze the chemical composition of worn surface, finally the wear mechanism of segment in working process is judged and the influence regulars of the environmental factors on the material wear behaviors are found. The test and analysis results show that under certain load, the wear of the segment changes into oxidation wear from abrasive wear step by step with the temperature increases, and the wear degree reduces; under certain temperature, the main wear mechanism of segment changes into spalling wear from abrasive wear with the load increases, and the wear degree slightly increases. The proposed research provides a theoretical foundation and a practical reference for optimizing the wear behavior and extending the working life of segment.

Growth Habit of Polar Crystal ZnO by Solid-vapor Method

Crystals of semiconductor ZnO were fabricated by means of solid-vapor growth method-carbon thermal reduction. Powder X-ray diffraction and field emission scanning electron microscope were used to characterize the phase and morphology of the samples. The results showed that the samples were wurtzite ZnO crystals and anisotropy of crystal growth relied on reaction temperature in solid-vapor process. The crystals synthesized at different temperatures were of short column-like shape, flat top hexagon pyramidal-like shape and polyhedron shape. The growth mechanisms of the above three kinds of crystal were consistent with the theory of growth basic structural unit of negative ion coordination polyhedron. At first, Zn2＋ and four O2- form [Zn-O4]6- coordination tetrahedron at any temperature. Then, tetrahedrons stack in different ways into different morphology crystal at different temperatures.

Structure and Optical Properties of ZnO Thin Films Prepared by the Czochralski Method

The zinc oxide seed film was coated on conductive glass (FTO) substrate by the Czochralski method,Zinc acetate and hexamethylenetetramine were used as raw materials to prepare growth solution,and then ZnO film was prepared by a low-temperature solution method.The effects of annealing temperature on the morphology,structure,stress and optical properties of ZnO films were studied.The thin films were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),UV-visible absorption spectra (UV-vis),photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS).The results show that the films are ZnO nanorods.With the increase of annealing temperature,the diameter of the rod increases,and the nanorods tend to be oriented.The band gap of the sample obtained from the light absorption spectra first increases and then decreases with the increase of annealing temperature.When the annealing temperature is 350 ℃,the crystallinity of zinc oxide film is the highest,the band gap is close to the theoretical value of pure ZnO.

Influence of Mercerization on Cotton Fiber Varieties from Different Regions

The influence of mercerization on cotton varieties from Africa,Xinjiang and Australia was studied. The micro-morphology,mechanical property and crystalline structure were analyzed before and after mercerization. Mercerization made the surface of fibers smoother which resulted in improved luster of fiberes with better results observed in Australia,Xinjiang and Africa cotton varieties respectively. Although fiber strenth increased due to orientation of intra fiber cellulose chains,there was a general in the crystallinity index amongst the three varieties of cotton after mercerization.Reduced crystallinity is a function of improved processability and thus Australian cotton is more processable than cotton from Africa and Xinjiang.

Preparation of ZrO_(2) Fibers by Template Impregnation Method

Viscose fiber templates(15 cm×15 cm×1 cm)were put into ZrOCl_(2) solutions of different concentrations(1,2 and 3 mol·L^(-1))and impregnated at different temperatures(20,40 and 60℃)for 20 h.After washing,centrifugation and drying,ZrO_(2) fiber precursors were obtained.ZrO_(2) fibers were prepared by heat treatment of the precursors at different temperatures(600,800,1000 and 1200℃)for 2 h.The effects of the impregnation temperature,the impregnation solution concentration and the heat treatment temperature on the microstructure and the phase composition of the ZrO_(2) fibers were studied.The results show that with the increase of the impregnation temperature from 20℃to 60℃and the impregnation solution concentration increase from 1 mol·L^(-1) to 3 mol·L^(-1),the microstructure of fiber cross section changes from flat to cylindrical,and the average fiber diameter increases,indicating that the increase of the impregnation solution concentration and the impregnation temperature is beneficial to increasing the adsorption capacity of Zr4+on viscose fiber templates.After heat treatment,ZrO_(2) fiber mainly exists in the form of monoclinic ZrO_(2).With the increase of the heat treatment temperature,the grains in ZrO_(2) fibers become larger and the crystallinity degree increases,meanwhile the fiber surface undergoes a transition from smooth to small grains and then to cracks.

Mechanical properties of molybdenum products prepared by using molybdenum powders with different micro-morphologies

Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.

Experiment on surface charge distribution of fine sediment

Surface charge distribution of particles is the fundamental problem for adsorption and desorption between sediment and contaminant. In this paper, we take quartz sand for example to measure its micro-morphology and surface charge distribution using the phase mode of the electrical force microscope. Then the statistical relation of micro-morphology and surface charge distribution is obtained. Results show that quartz sand possesses complex surface morphology, which has great impact on the charge distribution. Positive and negative charges mostly concentrate on the saddle, convex and concave parts of the surface, while distribute less in the groove, ridge and flat parts. This experiment provides a new method for understanding the process of flocculation in coastal and estuarine zone.