bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanodissection and noncontact imaging of plasmid DNA with an atomic force microscope
Authors: Geisler Bernd , Noll Frank , Hampp Norbert 
Published: June 2010

AbstractIn this paper we report that a combination of noncontact and contact atomic force microscopy is a convenient and reliable method for imaging and dissecting single plasmid deoxyribonucleic acid (DNA) strands on mica at ambient conditions without leaving feedback and without damage to the scanning tips. The width and thickness measured at different points of the DNA strands agree with literature data and are the same before and after dissection.
Microcratering within the lunar regolith — a theory and observation
Authors: Hammond Ernest C. , Berry F. Denise , Mitchell Franchezka , Barron Daniel , Cohen Samuel H. 
Published: June 2010

AbstractSince the Apollo 11 mission to the moon, there has been substantial analysis of the lunar rocks and soil grains, utilizing more recent advances in electron probe technologies. It is the objective of this research to revisit the theories concerning the microcratering within the lunar regolith. Recent theories have included the idea that the microcratering phenomenon was caused by meteoric impacting onto the lunar surface during early lunar history. Other theories have suggested that the microcratering was a result of secondary ejector associated with micrometeoric and meteoric impact. This research team suggests that microcratering may have been associated with primordial dust during and before the formation of our solar system.
The remote electron beam‐induced current analysis of grain boundaries in semiconducting and semi‐insulating materials
Authors: Holt D. B. 
Published: June 2010

AbstractWhen no charge collecting p‐n junction or Schottky barrier is present in the specimen, but two contacts are applied, conductive mode scanning electron microscope (SEM) observations known as remote electron beam‐induced current (REBIC) can be made. It was described as “remote” EBIC because the contacts to the specimen can lie at macroscopic distances from the beam impact point. In recent years, REBIC has been found to be useful not only for studies of grain boundaries in semiconducting silicon and germanium, but also in semi‐insulating materials such as the wider bandgap II‐VI compounds and electroceramic materials like varistor ZnO and positive temperature coefficient resistor (PTCR) BaTiO3. The principles of this method are outlined. Accounts are given of the five forms of charge collection and resistive contrast that appear at grain boundaries (GBs) in REBIC micrographs. These are (1) terraced contrast due to high resistivity boundary layers, (2) peak and trough (PAT) contrast due to charge on the boundary, (3) reversible contrast seen only under external voltage bias due to the beta‐conductive effect in a low conductivity boundary layer, (4) dark contrast due to enhanced recombination, and (5) bright contrast apparently due to reduced recombination. For comparison, the results of the extensive EBIC studies of GBs in Si and Ge are first outlined and then the results of recent REBIC grain boundary studies in both semiconducting and semi‐insulating materials are reviewed.
Use of low‐temperature field emission scanning electron microscopy to examine mites
Authors: Wergin William P. , Ochoa Ronald , Erbe Eric F. , Craemer Charnie , Raina Ashok K. 
Published: June 2010

AbstractPartly because mites are microscopic in size and fragile in nature, acarologists estimate that less than five percent of extant species have been taxonomically described. Recently, data from conventional scanning electron microscopy (SEM) have been used to facilitate the descriptions and complement the information that has been historically obtained with the light microscope. However, the conventional preparation techniques associated with SEM frequently prevent or compromise the results. This study evaluated the use of low‐temperature field emission SEM to image mites and their hosts. Results indicated that a modified cryofixation procedure, which was associated with this technique, retained the mites at their living/feeding sites in natural behavioral positions. Furthermore, the turgor of the specimens, even eggs and soft‐bodied species, was also maintained. The structure and orientation of delicate structures such as setae, which would be subjected to mechanical damage during conventional chemical fixation, dehydration, and drying, were also preserved after cryofixation. Field emission SEM, which provided useful magnification beyond that attainable with a conventional SEM, also enabled resolution of ultrastructural features, such as tenent hairs on the empodium and pores on the dorsal surface that had not previously been observed. These advantages indicate that the low‐temperature field emission SEM can provide important structural data that can be used to study the anatomy, morphology, and bioecology of mites.
A dynamical bragg equation for high‐order laue zone reflections
Authors: Chen S.‐J. , Howitt D. G. , Harker A. B. 
Published: June 2010

AbstractA dynamically corrected Bragg equation for high‐order Laue zone (HOLZ) reflections is derived directly from the Bloch wave formalism instead of the geometric argument used to deduce the kinematical Bragg condition. It differs from the kinematical Bragg equation by replacing the plane wave vector in the kinematical equation with the Bloch wave vectors. This dynamical equation reduces to the kinematical equation when the crystal potential is zero. It also demonstrates the occurrence of dynamical shifts for the HOLZ reflections but their absence for the zero‐order Laue zone (ZOLZ) reflections in the symmetrical Laue case.
Lengths measurements in microvascular corrosion castings: Two‐dimensional versus three‐dimensional morphometry
Authors: Minnich Bernd , Lametschwandtner Alois 
Published: June 2010

AbstractIn the present study we compared measurements of vessel lengths from (a) single‐digital scanning electron microscope (SEM) images of microvascular corrosion casts (VCCs) of gill filters of tadpoles of Xenopus laevis Daudin by two‐dimensional (2‐D) morphometry (Optimas 6.5, Optimas Corp., Bothell, Wash., USA; planar measurements) and (b) digital stereopairs by three‐dimensional (3‐D) morphometry (3D‐Morphometry, Minnich and Muska OEG, Salzburg). Depending on the spatial orientation of the vessels measured, we found a maximum difference of 58.84% (100 [3‐D]‐41.16 [2‐D]) in vessel lengths by 3‐D morphometry versus 2‐D morphometry, which, in multiple (segmental) lengths measurements or when determining space angles, might be even higher. Based on results we consider 3‐D morphometry of VCCs to be the method of choice for lengths measurements.
The reduction of the beam gas interactions in the variable pressure scanning electron microscope with the use of helium gas
Authors: Adamiak B. , Mathieu C. 
Published: June 2010

AbstractThis paper presents experimental observations on electron scattering by gases (helium and air) in the specimen chamber of a variable pressure scanning electron microscope. It shows an important reduction of the beam scattering with the use of helium gas, and the consequences for the x‐ray microanalysis are discussed.
Surface investigations on HgBr2 single crystals by using confocal scanning laser microscopy
Authors: Stanciu George A. , Polychroniadis E. K. 
Published: June 2010

AbstractA confocal scanning laser microscope operating at 514 and 488 nm has been used to obtain two‐dimensional (2‐D) images of the mercuric bromide (HgBr2) crystal surface by photoluminescence, reflection, and transmission phenomena. Our measurements indicate that regions showing a strong photoluminescence may appear on the surface. By processing the 2‐D images, we obtained the three‐dimensional images, which offer a better possibility for the investigation. The analysis of spectral lines may be correlated with the presence of the Hg impurities.
Three‐dimensional morphology of cerebellar climbing fibers. A study by means of confocal laser scanning microscopy and scanning electron microscopy
Authors: Castejon Orlando J. , Sims P. 
Published: June 2010

AbstractThe intracortical pathway of cerebellar climbing fibers have been traced by means of scanning electron microscpy (SEM) and confocal laser scanning microscopy (CLSM) to study the degree of lateral collateralization of these fibers in the granular Purkinje cell and molecular layers. Samples of teleost fish were processed for conventional and freeze‐fracture SEM. Samples of hamster cerebellum were examined by means of CLSM using FM4–64 as an intracellular stain. High resolution in lens SEM of primate cerebellar cortex was carried out using chromium coating. At scanning electron and confocal laser microscopy levels, the climbing fibers appeared at the white matter and granular layer as fine fibers with a typical arborescence or crossing‐over branching pattern, whereas the mossy fibers exhibited a characteristic dichotomous bifurcation. At the granular layer, the parent climbing fibers and their tendrils collaterals appeared to be surrounding granule and Golgi cells. At the interface between granule and Purkinje cell layers, the climbing fibers were observed giving off three types of collateral processes: those remaining in the granular layer, others approaching the Purkinje cell bodies, and a third type ascending directly to the molecular layer. At this layer, retrograde collaterals were seen descending to the granular layer. By field emission high‐resolution SEM of primate cerebellar cortex, the climbing fiber terminal collaterals were appreciated ending by means of round synaptic knobs upon the spines of secondary and tertiary Purkinje cell dendrites.
Three‐dimensional microscopy data exploration by interactive volume visualization
Authors: Fang Shiaofen , Dai Yi , Myers Frederick , Tuceryan Mihran , Dunn Kenneth 
Published: June 2010

AbstractThis paper presents a new volume visualization approach for three‐dimensional (3‐D) interactive microscopy data exploration. Because of their unique image characteristics, 3‐D microscopy data are often not able to be visualized effectively by conventional volume visualization techniques. In our approach, microscopy visualization is carried out in an interactive data exploration environment, based on a combination of interactive volume rendering techniques and image‐based transfer function design methods. Interactive volume rendering is achieved by using two‐dimensional (2‐D) texture mapping in a Shear‐Warp volume rendering algorithm. Image processing techniques are employed and integrated into the rendering pipeline for the definition and searching of appropriate transfer functions that best reflect the user's visualization intentions. These techniques have been implemented successfully in a prototype visualization system on low‐end and middle‐range SGI desktop workstations. Since only 2‐D texture mapping is required, the system can also be easily ported to PC platforms.
Semiconductor devices “from inside”
Authors: Mil'shtein S. 
Published: June 2010

AbstractOperation of any semiconductor device can be presented by unique configuration of the electrical field (potential) and charge (doping) distribution within the device. More specifically, the status of operation is described by the quasi‐Fermi energy (QFE) profile across the device. Visualization of the dynamic operation of the device and quantitative measurements of the QFE profile is provided by differential voltage contrast (DVC), which is a modification of the secondary electron imaging in a scanning electron microscope (SEM). The DVC consists of storing two images of a tested semiconductor device. Exposed to the electron beam is a cross section, for example, of a field effect transistor (FET). The first image, covering the entire inside of the FET from source to drain, is taken when the device is not biased. The second image of the same area is taken when the transistor is biased. The secondary electron signal is enhanced or retarded by actual distribution of a potential across the tested device. Subtraction pixel by pixel of the two carefully aligned images removes morphologic contrast from the screen, takes away surface features and contamination of the sample, and reveals the contribution of the electrical field to the changes of contrast. The calibration procedure allows measurement of the potential distribution with a precision of 0.05 V. The first derivative of a potential profile provides for distribution of the electrical field and the second derivative gives the doping profile across the tested device. A variety of semiconductor devices such as p‐n junctions, Zener diodes, MOSFET's, MESFET's, solar cells and optical detectors, quantum well lasers, etc., were tested. Videotaping of the tested devices allows us to observe the changes in the electrical field and charge distribution as the device operates in a wide range of electrical or optical signals.
Ultrastructure and reproduction behaviour of single CHO‐K1 cells exposed to near infrared femtosecond laser pulses
Authors: Oehring H. , Riemann I. , Fischer P. , Halbhuber K.‐J. , König K. 
Published: June 2010

AbstractIn the present work, the authors investigated ultrastructural changes as well as the reproduction behaviour of preselected single CHO‐K1 cells exposed to 170 femtosecond laser pulses at different power output levels in comparison with cells outside the illumination volume. The ultrashort laser pulses were provided by an 80 MHz Ti:sapphire laser at 780 nm. The cells were scanned ten times with a scan rate of 1/16 s−1. Single CHO‐K1 cells exposed to low mean power of 2 mW revealed no significant changes in ultrastructure after laser exposure. In some cases, changes of mitochondria with slight disordering of cristae were found. Cytoplasm was filled with vesicles that seemed to be released from Golgi stacks. Cells irradiated with higher powers demonstrated more dramatic changes in ultrastructure. A considerable number of swollen mitochondria in conjunction with loss of cristae was observed. The main event of mitochondrial changes was the formation of electron dense bodies in the mitochondrial matrix. In addition, lumen of endoplasmatic reticulum was enlarged. Highest applied mean laser power of 12.5 mW lead to complete destruction of mitochondria and their transformation to electron dense structures containing membrane material. Compared with cell targets irradiated with 2 mW mean power, the release of vesicles from Golgi stacks seemed to be rather moderate. Cells localised outside the laser beam revealed no ultrastructural changes. Low mean laser power at 2 mW was unable to impair the reproduction behaviour of CHO‐K1 cells. At higher laser power output levels, CHO‐K1 cells started to delay cell division. At 12.5 mW, no cell division occurred. The obtained results may be helpful in recommending parameters for safe femtosecond laser microscopy of living specimens.
Inexpensive, high‐quality optical relay for use in confocal scanning beam imaging
Authors: Ribes A. C. , Damaskinos S. , Dixon A. E. 
Published: June 2010

AbstractAn inexpensive, high optical‐quality relay lens made up of two eyepieces arranged in an afocal assembly for use in confocal scanning laser imaging is described. In the past we have used relays, within our confocal microscopes, made up of achromats with long focal lengths (≥10 cm), which take up large optical tracks and suffer from significant amounts of astigmatism and curvature of field. We quantify aberrations associated with achromat and eyepiece relays using CODE V optical design and analysis software. The eyepiece relay is found to be more compact, better corrected, and not significantly more expensive than its achromat counterpart. In addition to being used to interconnect two scanning mirrors optically as well as scanning mirrors with microscope objectives, it can form part of the optics in a confocal scanning laser MACROscope®‐Micro‐scope system (Biomedical Photometrics, Inc., Waterloo, Ontario, Canada). Due to design constraints, the MACRO‐scope®‐Microscope system cannot incorporate a conventional wide‐field microscope into its structure such as is done in most commercial confocal microscopes. The eyepiece relay is used as a stand‐alone, compact optical link between the scanning mirrors and the microscope objective. This consequently makes the MACROscope®‐Microscope system more compact and easier to commercialize.
The effects of space charge on contrast in images obtained using the environmental scanning electron microscope
Authors: Toth M. , Phillips M. R. 
Published: June 2010

AbstractWe present experimental evidence for the existence of a space charge in the environmental scanning electron microscope. Space charge formation is attributed to differences in the mobilities of negative and positive charge carriers in the imaging gas. A model is proposed for the behavior of space charge during image acquisition. The effects of space charge on images acquired using the gaseous secondary electron detector, ion current, and backscattered electron signals are interpreted using the proposed model.
Measures for spectral quality in low‐voltage X‐ray microanalysis
Authors: Newbury Dale E. 
Published: June 2010

AbstractCharacteristic x‐ray production with energetic electrons depends strongly on the overvoltage, the ratio of the incident beam energy to the critical excitation energy for the atomic species of interest. Low‐voltage x‐ray micro‐analysis (beam energy ≤ 5 keV) is especially susceptible to artifacts due to sample charging because the overvoltage is low and even slight charging can strongly affect peak intensities. The Duane‐Hunt bremsstrahlung limit is a good diagnostic to detect sample charging. Dynamic charging effects, however, can influence spectra despite an apparently satisfactory Duane‐Hunt limit. Dynamic charging effects must be examined by time series experiments, or through use of dynamic energy windows continuously measuring count rates placed across the spectrum. When charging is a problem, conductive surface coatings can eliminate the effects. When pristine surfaces must be examined without coating, the use of a conductive grid can control charging so that useful x‐ray spectra can be obtained.
Investigation of foreign substances in food
Authors: Charbonneau James E. 
Published: June 2010

AbstractScanning electron microscopy (SEM) together with energy‐dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to investigate foreign substances from seven categories of foreign substances in food. (1) Naturally occurring foreign substances—Using FTIR, a foreign substance was identified as a natural resin probably from the product. (2) Foreign substances introduced during food processing. Scanning electron microscopy‐EDS was used to identify a foreign material found on surf clams as calcium phosphate from a product/ingredient interaction. Using SEM‐EDS, a crystalline material in a meat product was identified as calcium salts of chloride and phosphate. Fourier transform infrared spectroscopy was used to identify foreign material that clogged an aerosol valve as chipboard. Using SEM‐EDS, the metal in the heel of a glass bottle was identified as copper sulfide‐containing metal inclusion. (3) Insects, reptiles, and rodents—Scanning electron microscopy was used to determine that a mouse found in food was not processed with the food, but entered the container after it left the factory. (4) Glass fragments—Glass from various sources can be distinguished from one another using SEM‐EDS either by the level of the major elements in glass or by the presence of elements in one glass, but not in another. (5) Glass‐like particles—Using SEM‐EDS, glass‐like particles found on beets were determined to be a fatty acid. (6) Metal foreign objects—Using SEM‐EDS, metals from a variety of sources can be easily distinguished. For example, a tin‐soldered container can be distinguished from a lead‐soldered can. Using SEM‐EDS, the metal fiber found on the bottom of a two‐piece can likely enter the can during the final stage of the manufacture of the drawn and ironed food can. (7) Drug capsule identification—Fourier transform infrared spectroscopy was used to determine that a pill found in food was ibuprofen.
On the electrical properties of dislocations in ZnS using electric force microscopy
Authors: Bai G. F. , Petrenko V. F. , Baker I. 
Published: June 2010

AbstractA combination of electric force microscopy (EFM) and noncontact atomic force microscopy (AFM) was used to study microscratching‐induced dislocations in sphaleritic ZnS single crystals. Dislocation bands predominantly consisting of either anion‐type (S) or cation‐type (Zn) dislocations were induced by scratching along either [111] or [111] on a (110) surface. A significant difference of local distortions in electrical potential between the S(g) and Zn(g) dislocation bands was observed from the EFM images. Electric charges of these dislocations were determined quantitatively and the results were compared with theoretical models.
Mapping piezoelectric‐field distribution in gallium nitride with scanning second‐harmonic generation microscopy
Authors: Sun Chi‐Kuang , Chu Shih‐Wei , Tai Shi‐Peng , Keller Stacia , Abare A. , Mishra U. K. , Denbaars Steven P. 
Published: June 2010

AbstractTaking advantage of the electric field‐enhanced second‐harmonic generation effect in bulk gallium nitride (GaN) and indium gallium nitride (InGaN) quantum wells, we demonstrated the piezoelectric field distribution mapping in bulk GaN and InGaN multiple‐quantum‐well (MQW) samples using scanning second‐harmonic generation (SHG) microscopy. Scanning SHG microscopy and the accompanying third‐harmonic generation (THG) microscopy of the bulk GaN sample were demonstrated using a femtosecond Cr:forsterite laser at a wavelength of 1230 nm. Taking advantage of the off‐resonant electric field‐enhanced SHG effect and the bandtail state‐resonance THG effect, the second‐ and third‐harmonic generation microscopic images obtained revealed the piezoelectric field and bandtail state distributions in a GaN sample. Combined with 720 nm wavelength excited two‐photon fluorescence microscopy in the same sample, the increased defect density around the defect area was found to suppress bandedge photoluminescence, to increase yellow luminescence, to increase bandtail state density, and to decrease residue piezoelectric field intensity. Scanning SHG microscopy of the InGaN MQW sample was resonant excited with 800 nm femtosecond pulses from a Ti:sapphire laser in order to suppress SHG contribution from the bulk GaN substrate. Taking advantage of the strong piezoelectric field inside the InGaN quantum well, the wavelength resonant effect, and the electric field‐enhanced SHG effect of InGaN quantum wells, resonant scanning SHG microscopy revealed the piezoelectric field distribution inside the wells. Combined with accompanying three‐photon fluorescence microscopy from the bulk GaN substrate underneath the quantum wells, the direct correspondence between the piezoelectric field strength inside the quantum well and the substrate quality can be obtained. According to our study, the GaN substrate area with bright bandedge luminescence corresponds to the area with strong SHG signals indicating a higher stained‐induced piezoelectric field. These scanning harmonic generation microscopies exhibit superior images of the piezoelectric field and defect state distributions in GaN and InGaN MQWs not available before. Combining with scanning multiphoton fluorescence microscopy, these techniques open new ways for the physical property study of this important material system and can provide interesting details that are not readily available by other microscopic techniques.