bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring the structure of a hydrogen cyanide polymer by electron spin resonance and scanning force microscopy
Authors: Eastman M. P. , Helfrich F. S. E. , Umantsev A , Porter T. L. , Weber R. 
Published: June 2010

AbstractAqueous solutions of potassium cyanide and ammonium hydroxide are known to yield a heterogeneous cyanide polymer, containing paramagnetic sites and biologically significant substructures including polypeptides. Here, such solutions were used to prepare various samples of polymer for study by X‐band and W‐band electron spin resonance (ESR), scanning electron microscopy (SEM), and scanning force microscopy (SFM). Elemental composition of a typical sample of the polymer was C‐35.2%, N‐38.47%, O‐14.51%, and H‐ 4.13%, exposing the polymer to 6M HCl hydrolyzed portions of the polymer and released glycine and traces of other amino acids. The X‐band ESR spectra consist of a single slightly asymmetric line centered at g = 2.003; spin concentration measurements made at X‐band using a nitroxide radical standard yield approximate radical concentrations of 1018 spins/gm. W‐band ESR indicates the presence of a single rhombic paramagnetic site with gx = 2.0025, gy = 2.0030, and gz = 2.0048 and the possibility of small 14N hyperfine splittings. The ESR spin echo studies yield a longitudinal relaxation time, T1, of 75 μS and a short‐phase memory relaxation time, Tm, of about 300 nS. Scanning electron microscopy studies of the polymer show that it is made of ellipsoidal particles about one micron in size. The particles tend to clump together when suspended in aqueous solution. The particles disperse and dissolve in dimethyl sulfoxide (DMSO); when these solutions dry on microscope slides, optical microscopy shows a branched island morphology for the polymer. This morphology is reminiscent of snowflakes and is identified as dendritic. Phase contrast SFM of the dendritic arms show a striking segregation and ordering of various components of the polymer. Paramagnetic sites are conserved in the series of steps leading to dendritic structures.
Computer‐assisted stereology: Point fraction of lung parenchyma and alveolar surface density in fetal and newborn sheep
Authors: Davey M. G. , Hedrick H. L. , Bouchard S. , Adzick N. S. , Flake A. W. , Doolin E. J. 
Published: June 2010

AbstractThe aim of this study was to determine the accuracy of a new computer‐assisted stereological technique in obtaining structural information of the lung. We compared the point fraction of lung parenchyma (Pp) and alveolar surface density (Sv) obtained by established manual point/intercept counting methods and compared them with those obtained using a computer‐assisted method. Lung tissues obtained from normally grown fetal sheep (n=6) and from newborn lambs with severe lung hypoplasia (n=5) were inflation fixed via the trachea and processed for light microscopy. In verification‐of‐technique experiments, Pp and Sv correlated well with known values. There was a significant linear correlation between manual and computer‐assisted stereological measurements for values of Pp (r2 = 0.92) and Sv (r2 = 0.98). Our data lead us to believe that the computer‐assisted stereological technique described in this study provides accurate estimates of Pp and Sv and hence may be a valuable tool for evaluating the effects of factors upon structural development of the lung.
Identification of fat, protein matrix, and water/starch on microscopy images of sausages by a principal component analysis‐based segmentation scheme
Authors: Kohler Achim , Høst Vibeke , Enersen Grethe , Ofstad Ragni 
Published: June 2010

AbstractA color‐based segmentation scheme applied to microscopy images of cryosectioned sausages is proposed. The segmentation scheme is capable of segmenting three different levels on the microscopy images: the fat particles, the protein matrix, and water/starch. The method is based on principal component analysis. A user‐friendly program was developed for the manual segmentation of a selection of image pixels by microscopists. Principal component models based on the manually classified pixels are then used to segment fat, protein matrix, and starch/water on microscopy images. The program can also be used as a training tool for microscopists.
Atomic force microscopic imaging of 30 nm chromatin fiber from partially relaxed plant chromosomes
Authors: Sugiyama S. , Yoshino T. , Kanahara H. , Kobori T. , Ohtani T. 
Published: June 2010

AbstractWe have developed a procedure for partially relaxing the barley metaphase chromosomes and exposing fibrous structures from the chromosomes. The observation by atomic force microscopy (AFM) showed that the fibrous structures are typically 0.5 to 1 μm long and 40 to 50 nm in diameter. In higher magnification imaging, we found the fibrous structures were composed of aligned granules and looked like “knobby fiber.” These observations are consistent with previously reported features of chromatin fiber observed by AFM and scanning electron microscopy, suggesting that the structures correspond to 30 nm chromatin fibers. We observed the chromatin fiber extending straight from the periphery of the chromosomes in most cases, but fibers with different shapes, such as loop and spiral, were also observed. The procedure reported here will provide a new approach for observing the organization of chromatin fiber to higher‐order structures by AFM and other high‐resolution microscopy.
Experimental resolution measurement in critical dimension scanning electron microscope metrology
Authors: Lorusso G. F. , Joy D. C. 
Published: June 2010

AbstractBy applying the basic principles of metrology we discuss how to define the standards that any experimental method to measure resolution has to obey. Our results clearly indicate the need to apply a calibration procedure when designing algorithms to estimate resolution to satisfy accuracy requirements. Similarly, the precision of an algorithm has to be clearly specified. We compare here the performances of a variety of commonly used implementations of published methods, with that of an algorithm based on an approach known to be reliable. Our results confirm that when an algorithm is designed with the clear intent of satisfying metrology requirements, it demonstrates excellent accuracy, precision, and lack of sensitivity to the noise level, as is desirable. As a consequence, the algorithm will have the ability to measure accurately the point spread function convoluted in the image, thus paving the way for quantitative deconvolution techniques.
Electron microscopy of mammalian cells in the absence of fixing, freezing, dehydration, or specimen coating
Authors: Stokes D. J. , Rea S. M. , Best S. M. , Bonfield W. 
Published: June 2010

AbstractHuman osteoblast‐like (bone‐forming) cells were imaged using environmental scanning electron microscopy (ESEM). The cells were hydrated, unfrozen, and uncoated. Specimens were cooled to 3°C and imaged in water vapor, with partial pressures varying from saturated conditions to a humidity of approximately 50%, relative to pure water. The ESEM images show the presence of cell nuclei, nucleoli, and cytoplasmic membranes. Comparisons between chemically fixed and unfixed specimens (neither dried nor coated) show that cell morphologies are similar in both cases. These results are compared with a fixed, dried, carbon‐coated specimen. Thermodynamic and kinetic arguments are used to show that humidities significantly lower than 100% correspond to metastable states suitable for stabilizing hydrated biological tissues and cells. The ability to perform observations with minimal specimen preparation is potentially useful for studying interactions between mammalian cells and biomaterials that are developed for tissue engineering. The methods employed are equally applicable to the study of specimens in the biological, materials, and physical sciences where careful control over specimen stability is required.
Quantitative measurements of charging in a gaseous environment
Authors: Tang Xiaohu , Joy David C. 
Published: June 2010

AbstractCharge accumulation in insulating or semiconducting samples due to electron beam irradiation is one of the key problems in electron microscopy. One of the most promising techniques for reducing the severity of such charging is to surround the sample with a low‐pressure atmosphere of a gas. The charging behavior of a number of materials, surrounded by a variety of gases, has been determined to identify the important factors which control charging under these conditions. The magnitude of the surface potential was deduced from an analysis of xray spectra from the surface. The relationship between surface charge, gas pressure, and gas type are measured, and the charging reduction efficiency (CRE) is compared.
Comparison in spatial spreads of secondary electron information between scanning ion and scanning electron microscopy
Authors: Ishitani Tohru , Ohya Kaoru 
Published: June 2010

AbstractMonte Carlo simulations have been carried out to compare the spatial spreads of secondary electron (SE) information in scanning ion microscopy (SIM) with scanning electron microscopy (SEM). Under Ga ion impacts, the SEs are excited by three kinds of collision‐partners, that is, projectile ion, recoiled target atom, and target electron. The latter two partners dominantly contribute to the total SE yield γ for the materials of low atomic number Z2. For the materials of high Z2, on the other hand, the projectile ions dominantly contribute to γ. These Z2 dependencies generally cause the γ yield to decrease with an increasing Z2, in contrast with the SE yield δ under electron impacts. Most of the SEs are produced in the surface layer of about 5λ in depth (λ: the mean free path of SEs), as they are independent of the incident probe. Under 30 keV Ga ion impacts, the spatial spread of SE information is roughly as small as 10 nm, decreasing with an increasing Z2. Under 10 keV electron impacts, the SE1 excited by the primary electrons has a small spatial spread of about 5λ, but the SEII excited by the backscattered electrons has a large one of several 10 to several 100 nanometers, decreasing with an increasing Z2. The main cause of a small spread of SE information at ion impact is the short ranges of the projectile ions returning to the surface to escape as backscattered ions, the recoiled target atoms, and the target electrons in collision cascade. The 30 keV Ga‐SIM imaging is better than the 10 keV SEM imaging in spatial resolution for the structure/material measurements. Here, zero‐size probes are assumed.
Possibility of charge contrast imaging of polymeric materials
Authors: Gauvin Raynald , Robertson Kevin , Leberre Jean‐Francois , Finch James , Griffin Brendan J. 
Published: June 2010

AbstractPreliminary results illustrate the possibility of charge contrast imaging (CCI) of polymeric materials. Possible CCI images of low‐density polyethylene and polyvinyl chloride reveal details that may aid in the characterization of the microstructure of polymeric materials. These pictures were obtained with a Hitachi S‐3000N variable pressure scanning electron microscope with the environmental secondary electron detector (ESED).
Using monte carlo simulation for accurate critical dimension metrology of super small isolated poly‐lines
Authors: Karabekov Albert , Zoran Oren , Rosenberg Zvika , Eytan Guy 
Published: June 2010

AbstractWith the reduction of critical dimensions (CD) of physical gate lines, standard methods for evaluating bottom CD from the scanning electron microscope (SEM) signal become inaccurate. The two peaks, originating from the line edges, merge into a single peak, and the correct position of the topographical top and bottom points is not clear. A general Monte Carlo simulation program, developed to model SEM signals, was used to analyze the signals emerging from ultra small silicon lines. By correlating the simulated signals with the features, we deduced the location of the top and bottom points. This analysis was done for lines with various CDs, sidewall angles, and corner rounding, as well as for different spot sizes. This work shows the feasibility of using SEM for measuring ultranarrow features and supply data for algorithm development.
Dynamic three‐dimensional visualization of collagen matrix remodeling and cytoskeletal organization in living corneal fibroblasts
Authors: Petroll W. Matthew , Cavanagh H. Dwight , Jester James V. 
Published: June 2010

AbstractThe remodeling of extracellular matrices by cells plays a defining role in developmental morphogenesis and wound healing, as well as in tissue engineering. Three‐dimensional (3‐D) type I collagen matrices have been used extensively as an in vitro model for studying cell‐induced matrix reorganization at the macroscopic level. However, few studies have directly assessed the dynamic process of 3‐D matrix remodeling at the cellular and sub‐cellular level. We recently developed an experimental model for investigating cell‐matrix mechanical interactions by plating green fluorescen protein (GFP)‐zyxin transfected cells inside fibrillar collagen matrices and performing high‐magnification time‐lapse differential interference microscopy (DIC) and wide‐field fluorescent imaging. In this study, we extend this experimental model by performing four‐dimensional (4‐D) reflected light and fluorescent confocal imaging (using either visible light or multiphoton excitation) of living corneal fibroblasts transfected to express GFP‐zyxin or GFP‐α‐actinin, 18 h after plating inside 3‐D collagen matrices. Reflected light confocal imaging allowed detailed visualization of the cells and the fibrillar collagen surrounding them. By overlaying maximum intensity projections of reflected light and GFP‐zyxin or GFP‐α‐actinin images and generating stereo pair reconstructions, 3‐D interactions between focal adhesions and collagen fibrils in living cells could be visualized directly. Focal adhesions were generally oriented parallel to the direction of collagen fibril alignment in front of the cell. Killing the cells induced relaxation of transient cell‐induced tension on the matrix; however, significant permanent remodeling always remained. Time‐lapse 3‐D imaging demonstrated an active response to the Rho‐kinase inhibitor Y‐27632, as indicated by cell elongation, extracellular matrix relaxation, and extension of pseudopodial processes. It is interesting that, at higher cell densities, groups of collagen fibrils were compacted and aligned into straps between neighboring cells. Overall, the continued development and application of this new approach should provide important insights into the basic underlying biochemical and biomechanical regulatory mechanisms controlling matrix remodeling by corneal fibroblasts.
Quantitative electron probe microanalysis of rough targets: Testing the peak‐to‐local background method
Authors: Newbury Dale E. 
Published: June 2010

AbstractRough samples with topography on a scale that is much greater than the micrometer dimensions of the electron interaction volume present an extreme challenge to quantitative electron beam x‐ray microanalysis with energy‐dispersive x‐ray spectrometry. Conventional quantitative analysis procedures for flat, bulk specimens become subject to large systematic errors due to the action of geometric effects on electron scattering and the x‐ray absorption path compared with the ideal flat sample. The best practical approach is to minimize geometric effects through specimen reorientation using a multiaxis sample stage to obtain the least compromised spectrum. When rough samples must be analyzed, corrections for geometric factors are possible by the peak‐to‐local background (P/B) method. Correction factors as a function of photon energy can be determined by the use of reference background spectra that are either measured locally or calculated from pure element spectra and estimated compositions. Significant improvements in accuracy can be achieved with the P/B method over conventional analysis with simple normalization.
Practical method for high‐resolution imaging of polymers by low‐voltage scanning electron microscopy
Authors: Gaillard Cedric , Stadelmann Pierre A. , Plummer Christopher J. G. , Fuchs Gilbert 
Published: June 2010

AbstractMorphologic characterization of polymers by scanning electron microscopy (SEM) is often made difficult by their sensitivity to electron beam damage. We describe here a specimen preparation method for the imaging of polymer blends by low‐voltage SEM (LV‐SEM) that improves their stability in the electron beam and hence facilitates focusing and recording of high magnification images. Its application to nanosized core‐shell latexes embedded in a polymethylmethacrylate matrix and semicrystalline polypropylene/ethylene‐propylene rubber blends is discussed.
Reduction in acquisition time of scanning electron microscopy image using complex hysteresis smoothing
Authors: Oho Eisaku 
Published: June 2010

AbstractComplex hysteresis smoothing (CHS), which was developed for noise removal of scanning electron microscopy (SEM) images some years ago, is utilized in acquisition of an SEM image. When using CHS together, recording time can be reduced without problems by about one‐third under the condition of SEM signal with a comparatively high signal‐to‐noise ratio (SNR). We do not recognize artificiality in a CHS‐filtered image, because it has some advantages, that is, no degradation of resolution, only one easily chosen processing parameter (this parameter can be fixed and used in this study), and no processing artifacts. This originates in the fact that its criterion for distinguishing noise depends simply on the amplitude of the SEM signal. The automation of reduction in acquisition time is not difficult, because CHS successfully works for almost all varieties of SEM images with a fairly high SNR.
Using the atomic force microscope to observe and study the ultrastructure of the living biu‐87 cells of the human bladder cancer
Authors: Chen Bin , Wang Qi , Han Li 
Published: June 2010

AbstractIn this study, the ultrastructure of living BIU‐87 cells of human bladder cancer was mapped using atomic force microscopy to reveal the dynamic change of single cancerous cell division. Simultaneously, the feasibility and functional reliability of the atomic force microscope (AFM) were established and a laboratory model using AFM to study living cancerous cells was created. In this experiment, BIU‐87 cells of human bladder cancer were cultured by conventional methods and grown in gelatin‐treated dishes. A thermostat was used for preserving the cell's living temperature. Scanning of these cells using AFM was carried out in physiologic condition. The AFM images of the ultrastructure of living BIU‐87 cells as well as those of the cell's membrane and cytoskeleton were very clear. The dynamic phenomenon of single cell division was observed. It was concluded that the AFM was able to observe and depict the ultrastructure of living cells of human bladder cancer directly and in real time. This experimental model is expected to play an important role in elucidating the cancerous mechanism of bladder normal cells at the atomic or nanometer level.
Compact multiphoton/single photon laser scanning microscope for spectral imaging and fluorescence lifetime imaging
Authors: Ulrich Volker , Fischer Peter , Riemann Iris , König Karsten 
Published: June 2010

AbstractAn inverted fluorescence microscope was upgraded into a compact three‐dimensional laser scanning microscope (LSM) of 65 × 62 × 48 cm dimensions by means of a fast kHz galvoscanner unit, a piezodriven z‐stage, and a picosecond (ps) 50 MHz laser diode at 405 nm. In addition, compact turn‐key near infrared femtosecond lasers have been employed to perform multiphoton fluorescence and second harmonic generation (SHG) microscopy. To expand the features of the compact LSM, a time‐correlated single photon counting unit as well as a Sagnac interferometer have been added to realize fluorescence lifetime imaging (FLIM) and spectral imaging. Using this unique five‐dimensional microscope, TauMap, single‐photon excited (SPE), and two‐photon excited (TPE) cellular fluorescence as well as intratissue autofluorescence of water plant leaves have been investigated with submicron spatial resolution, <270 ps temporal resolution, and 10 nm spectral resolution.
Composition and stress analysis in Si structures using micro‐raman spectroscopy
Authors: McCarthy J. , Perova T. S. , Moore R. A. , Bhattacharya S. , Gamble H. , Armstrong B. M. 
Published: June 2010

AbstractStrained silicon (Si) technology enables improvements in complementary metal oxide semiconductor (CMOS) performance and functionality via replacement of the bulk, cubic‐crystal Si substrate with an Si substrate that contains a tetragonally distorted, biaxially strained Si thin film at the surface. Here we use Raman spectroscopy to allow us to characterise growth processes of strained si, and to characterise the resulting level of strain/stress in the si and the effect it has on the underlying layer of graded SiGe.
Secondary and backscattered electron imaging of weathered chromian spinel
Authors: Pooley Gregory D. 
Published: June 2010

AbstractSecondary (SE) and backscattered electron (BSE) imaging as well as x‐ray microanalysis have demonstrated that the weathering of chromian spinel occurs as a progressive form of alteration. Numerous chemical discriminant analysis methods based on the composition of chromian spinel are used to locate valuable deposits of minerals. These methods will be misleading if the correct interpretation of the weathering of chromian spinel and the subsequent pattern of changes in its mineral chemistry are not properly assessed using scanning electron microscopy. This assessment is vital in understanding the geological processes involved and the economic potential of any indicated deposit. Minerals such as chromian spinel, pyrope garnet, and picroilmenite are considered to be highly resistant to weathering and abrasion and are therefore useful in the search for associated valuable deposits of diamond, nickel, platinum, and gold. Known as indicator minerals, they are usually present in relatively large concentrations compared with the target mineral (e.g., diamond) and form large and often subtle dispersion anomalies adjacent to the deposit. Chromian spinel has long been regarded as a stable indicator mineral; however, detailed SE and BSE imaging indicates that many of the chromian spinels that are routinely examined using scanning electron microscopes (SEM) and microprobes are extensively altered. Secondary electron and BSE imaging of weathered chromian spinel in a normal SEM provides valuable data on the form and chemical style of the alteration. Secondary electron imaging of weathered chromian spinel in the environmental SEM (ESEM) not only enhances the difference in atomic number between unaltered and altered areas but also allows high‐resolution imaging of these very fine replacement textures.