V(Z) curve formation of solid spherical microparticles in scanning acoustic microscopy

Information about the properties of materials in acoustic microscopy can be obtained in the form of the V(Z) curves. The purpose of this paper is to present the theoretical and experimental study of the V(Z) curve formation for solid spheres. It is shown that an investigation of the position of different peaks in the V(Z) curves is useful to determine the size and acoustical properties of a spherical particle.     

Characterization of the annealed (0001) surface of sapphire (alpha-Al2O3) and interaction with silver by reflection electron microscopy and scanning reflection electron microscopy.

Annealed (0001) surfaces of single-crystal sapphire (alpha-Al2O3) rod have been studied in the electron microscope using reflection electron microscopy (REM), scanning reflection electron microscopy (SREM), and reflection high energy electron diffraction (RHEED). Annealed surfaces of (0001) sapphire are vicinal and characterized by close-packed (0001)-oriented terraces separated by faceted multiple-height steps, with edges parallel to energetically preferred low-index directions (less than 1010 greater than and less than 1120 greater than). These structural features are not seen on cleaved surfaces or polished surfaces treated at temperatures less than 1,250 degrees C. Oxygen-annealing produces clean surfaces which prove useful for investigating the interaction of deposited metals with the (0001) sapphire. Both REM and SREM (with microdiffraction spots) techniques have been used to observe fine structure of flat Ag islands on the scale of 1-100 nm on the (0001)-oriented terraces as well as aggregations at the steps. A preliminary result on interaction with Cu is also included.     

Degradation, amorphization, and recrystallization of ion bombarded Si(111) surfaces studied by in situ reflection electron microscopy and reflection high energy electron diffraction techniques.

In this paper we report the effect of noble gas ions bombardment on the degradation of atomically flat Si(111) surfaces at room and high (400 degrees C-600 degrees C) temperatures. Reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been used to characterize the topography and structure of the as-implanted and post annealed surface layers. It is shown that the fading of the specularly reflected beam is not directly related to the amorphization of the surface. This experimental study has also evidenced the difficulties one meets to regrow a defect-free material after amorphization by noble gas bombardment. For high temperature for which the amorphization is not possible, the surface loses its stepped structure and turns into a monocrystalline but atomically rough surface. This roughness is a function of substrate temperature.     

Use of the approximations in cell studies by total internal reflection fluorescence microscopy (TIRF)

In determining cell parameters by the use of total internal reflectance fluorescence microscopy it is necessary to evaluate the electric field strength in the neighbourhood of the cell. It has been suggested that the true field distribution be assumed to be of exponential form. In some circumstances, this approximation gives rise to errors and seriously incorrect results are obtained. The true field distribution is easily obtained numerically so the use of an exponential approximation is unnecessary and errors are avoided.     

In situ observation of the initial growth process of carbon nanotubes by time-resolved high resolution transmission electron microscopy

We succeeded in plan-view dynamic observation of the initial formation process of carbon nanotubes from β-SiC( 1 1 1 ) surfaces by time-resolved high resolution transmission electron microscopy. At 1360 °C, the flakes of graphite layers of a fibre orientation were formed on the SiC( 1 1 1 ) surfaces. From the graphite layers, carbon nanotubes were formed perpendicular to the ( 1 1 1 ) plane of the SiC. A scanning tunnelling microscopy observation showed that the end of carbon nanotube was closed. These results indicate that the caps of the carbon nanotubes are formed by a lift of a part of the graphene along the [ 1 1 1 ] direction of the SiC through generation of pentagons and heptagons. Two types of carbon nanotube, single-wall and double-wall, were observed in plan-view images. Different image intensity between an outer ring and an inner ring in double-wall nanotubes suggests that the inner layers of multiwall nanotubes are formed after the outer ones.     

Observation of lattice fringes of the Si(111)–7×7 structure by reflection electron microscopy*

Lattice fringes of Si(111)–7×7 reconstructed surface structure in reflection electron microscopy (REM) are observed for the first time, and their characteristic features are presented. Due to a glancing reflection condition in REM, the fringes with a spacing of 2.3 nm of the 7×7 surface structure lattice are seen in a region of a certain defocus range (about 6–8 μm) in a foreshortened image. The glancing reflection geometry also results in a complicated dependence of fringe directions on imaging conditions (beam alignment, crystal orientation). A shift of the fringes across the surface atomic steps and out of phase boundaries is observed.     

Simultaneous measurement of magnetic vortex polarity and chirality using scanning electron microscopy with polarization analysis (SEMPA)

The magnetic vortex structure is an equilibrium configuration frequently found in patterned magnetic nanostructures. It is characterized by an in-plane curling of the magnetization with clockwise or anticlockwise chirality and by an out-of-plane vortex core that can have a positive or negative polarity. The small size of the vortex core, on the order of 10 nm, makes it technologically interesting due to potential data storage, but also difficult to measure or image directly. In this work, we used Scanning Electron Microscopy with Polarization Analysis (SEMPA) to directly image magnetic vortex cores in patterned NiFe/Ta bilayer structures. With SEMPA we can simultaneously measure the in-plane and the out-of-plane component of the surface magnetization and thereby determine both the vortex chirality and the vortex core polarity in a single measurement. Our magnetic simulation of the vortex core, considering only the exchange and magnetostatic energy, is in good agreement with the SEMPA measurement of the magnetization when other experimental factors are taken into account.     

DPCO—CTMAB分光光度法测定聚烯烃中的钒

本文研究以钒(Ⅴ)一二苯偶氮羰酰肼(DPCO)一溴化十六烷基三甲铵(CT-MAB)为络合体系,分光光度法测定聚烯烃中的钒(V),实验结果表明,以pH值为6.0的醋酸-醋酸钠作为缓冲溶液,络合物的最大吸收峰位于535nm处,钒(V)含量在0-30μg/25mL范围内服从比尔定律,其表观摩尔吸收系数ε_(535)=4.23 × 10~4L/mol/cm相关系数r=0.99998。采用硫脲-盐酸羟胺作为联合掩蔽剂,消除干扰离子的影响。人工合成样的平均回收率为104.12%,RSD为1.60%。聚丙烯、聚乙烯中钒(V)的加标平均回收率分别为101.78%和101.72%,RSD分别为3.74%和2.15%。     

Video-rate confocal reflection microscopy of neoplastic cells: Rate of intracellular movement and peripheral motility characteristic of neoplastic cell line (RSK4) with high degree of growth independence in vitro

Video-rate laser confocal interference reflection microscopy was used to demonstrate rapid motion of intracellular organelles and features at the cell periphery in a fully transformed neoplastic cell line, RSK4, and in four other neoplastic cell populations. In the RSK4 cells, vibrational and trafficking movements of intracellular particles at a rate greater than 25 Hz and ranging down to 5 Hz were recorded. Rapidly moving processes changed to ruffles, then microspikes, and previously undetectable ephemeral intercellular contacts were seen. Dynamic cyclical changes were revealed in the sizes of the podosomal close contacts of the transformed cells. The visibility of such features and the temporal and spatial resolution are improved over earlier methods. The fact that fast cellular and intracellular movements can be detected with this microscopic technique offers new possibilities in attempting to recognise differences between unimpaired living cells, and it may prove useful in the identification of malignant cells.     

Seed morphoanatomy of the genus Passiflora L. (Passifloraceae) by scanning electron microscopy and light microscopy

Morphoanatomical analysis of seeds contributes to knowledge of the development of seedlings and identification of species, as well as supporting conservation studies. The conservation of the species belonging to the Passiflora genus is crucial due to of the threats to the genetic resources of these species. Thus, the objective of this study was to morphoanatomically characterize Passiflora seeds, verify possible injuries to the tissues after cryopreservation and thus contribute to the conservation strategies of the species of this genus. Initially, seeds of Passiflora coccinea, P. edulis, P. gibertii, P. maliformis, P. morifolia, P. setacea, P. suberosa, and P. tenuifila collected from the Passion Fruit Active Germplasm Bank of the Embrapa Cassava and Fruits research unit (Embrapa Mandioca e Fruticultura) were analyzed. Then, their length, width and thickness, shape of the base and tip, and ornamentations present on the body and edge of the seeds were evaluated. The seeds of the species were placed in cryotubes and immersed in liquid nitrogen to assess possible cryoinjuries. The tegument and tissues of the seeds were examined by scanning electron microscopy. The seeds had varied biometric data, with average values of 4.63 mm for length, 3.28 mm for width, and 1.51 mm for thickness. Six ornamentation types were observed: reticulate for the species P. coccinea; finely reticulate for P. edulis; foveolate reticulate for P. gibertii and P. setacea; alveolate reticulate for P. maliformis and P. tenuifila; coarsely reticulate for P. morifolia; and falsifoveolate reticulate for P. suberosa. Some seeds suffered tegument cracks due to the freezing in liquid nitrogen, but without physiological damages to the embryo and endosperm. The cryopreservation of the seeds in the presence of the tegument significantly reduced the cryoinjuries caused to the embryo. Cryopreservation can be promising for long-term conservation of passion fruit seeds.     

The ovary of Lagostomus maximus (Mammalia, Rodentia): an analysis by confocal microscopy

Lagostomus maximus is a notable mammalian model for reproductive studies. Females have an extremely high ovulation rate, which is due to down-regulation of the follicular apoptosis pathway, which ensures a large pool of developing follicles. This large pool is supported by the convoluted anatomy of the mature ovary, whose germinal tissue is found in irregularly curved ridges throughout the cortex. Medullary tissue is restricted to a minimum. Lyso Tracker Red reconstruction under confocal laser scanning microscopy was used to recognize and measure all follicular stages from primordial to antral. Unlike most mammals in which early primordial follicles are just found in fetal life, the adult ovary shows regions packed with early primordial follicles. Follicle size ranged from 24 to 316 microm. We discuss the relationships of L. maximus follicles size with regard to other species of mammals and propose that the physiology of the adult viscacha ovary obeys to a neoteny process in the evolution of this species.     

Polyethylene glycol (PEG) embedding and subsequent de-embedding as a method for the correlation of light microscopy,scanning electron microscopy,and transmission electron microscopy

The polyethylene glycol (PEG) embedding and subsequent deembedding method was applied to the observation of general tissues in scanning electron microscopy (SEM). Resulting SEM images were of high quality. It was demonstrated that intermicroscopic correlation of images between light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) is easily and reliably done by means of the PEG method. In particular, the exact correlation of immuno-LM with SEM is shown to be of potential value.     

Asbestos fibres detected by scanning electron microscopy in the gallbladder of patients with malignant pleural mesothelioma (MPM)

Gallbladders from patients affected by both malignant pleural mesothelioma (MPM) and important gallbladder disorders were analyzed to verify the presence of asbestos fibres. Histological thin sections were analyzed by optical microscope and variable pressure scanning electron microscopy coupled with energy dispersive spectroscopy, allowing morphological and chemical characterization of each inorganic phase observed. Fibres of chrysotile and crocidolite, minerals regulated as asbestos, were identified. By immunohistochemical analysis, connective tissue was recognized as the incorporation site. These findings confirm that asbestos fibres can reach the gallbladders of patients with MPM, for whom the development of respiratory diseases confirms asbestos exposure.     

The indirect measurement of tensile strength by the new model FGMC (1, n)

The relationship between the tensile strength and Brinell hardness number of material is very intense, but a definite explicit or implicit function of them does not exist. The mechanical property of a material is a grey system because it will vary with the chemical ingredients and the procedures of heat treatment. Measuring the tensile strength is more difficult than the Brinell hardness number of a material especially for a higher temperature.The effectiveness of the first pair of original data by GMC (1, n) is researched in this paper. The results show that the modeling values and forecasts are independent of the first pair of original data. The grey prediction model presented in this paper is called the First-pair-of-data GMC (1, n), abbreviated as FGMC (1, n), which is based on GMC (1, n) but modeled with data including the messages from the first pair of original data. The accuracy of the indirect measurement of the tensile strength by FGMC (1, n) is satisfactory.     

Signal analysis of total internal reflection fluorescent speckle microscopy (TIR-FSM) and wide-field epi-fluorescence FSM of the actin cytoskeleton and focal adhesions in living cells

Fluorescent speckle microscopy (FSM) uses low levels of fluorescent proteins to create fluorescent speckles on cytoskeletal polymers in high‐resolution fluorescence images of living cells. The dynamics of speckles over time encode subunit turnover and motion of the cytoskeletal polymers. We sought to improve on current FSM technology by first expanding it to study the dynamics of a non‐polymeric macromolecular assembly, using focal adhesions as a test case, and second, to exploit for FSM the high contrast afforded by total internal reflection fluorescence microscopy (TIR‐FM). Here, we first demonstrate that low levels of expression of a green fluorescent protein (GFP) conjugate of the focal adhesion protein, vinculin, results in clusters of fluorescent vinculin speckles on the ventral cell surface, which by immunofluorescence labelling of total vinculin correspond to sparse labelling of dense focal adhesion structures. This demonstrates that the FSM principle can be applied to study focal adhesions. We then use both GFP‐vinculin expression and microinjected fluorescently labelled purified actin to compare quantitatively the speckle signal in FSM images of focal adhesions and the actin cytoskeleton in living cells by TIR‐FM and wide‐field epifluorescence microscopy. We use quantitative FSM image analysis software to define two new parameters for analysing FSM signal features that we can extract automatically: speckle modulation and speckle detectability. Our analysis shows that TIR‐FSM affords major improvements in these parameters compared with wide‐field epifluorescence FSM. Finally, we find that use of a crippled eukaryotic expression promoter for driving low‐level GFP‐fusion protein expression is a useful tool for FSM imaging. When used in time‐lapse mode, TIR‐FSM of actin and GFP‐conjugated focal adhesion proteins will allow quantification of molecular dynamics within interesting macromolecular assemblies at the ventral surface of living cells.     

Elimination of the effects of stray light in measurements by total internal reflection aqueous fluorescence (TIRAF)

Total internal reflection aqueous fluorescence has been shown to be capable of achieving spatial resolution in surface contours of about 1 nm. When used with highly structured objects, errors in measurements can arise from light scattered either by the object or within the body of the microscope. We describe how these errors can be eliminated when studying surface contours of human platelets.