bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cryo‐planing for cryo‐scanning electron microscopy
Authors: Nijsse Jaap , van Aelst Adriaan C. 
Published: June 2010

AbstractIn the past decade, investigators of cryo‐planing for low‐temperature scanning electron microscopy (cryo‐SEM) have developed techniques that enable observations of flat sample surfaces. This study reviews these sample preparation techniques, compares and contrasts their results, and introduces modifications that improve results from cryo‐planing. A prerequisite for all successful cryo‐planing required a stable attachment of the specimen to a holder. In most cases, clamping with a screw mechanism and using indium as space‐filler sufficed. Once this problem was solved, any of three existing cryo‐planing methods could be used to provide successful results: cryo‐milling, microtomy in a cold room, and cryo‐ultra‐microtomy. This study introduces modifications to the cryo‐planing technique that produces flat surfaces of any desired plane through a specimen. These flat surfaces of frozen, fully hydrated samples can be used to improve observations from cryo‐SEM as well as to enhance results from x‐ray microanalysis and (digital) image analysis. Cryo‐planing results of chrysanthemum (Dendranthema x grandiflorum Tzvelev) stems, hazel (Corylus avelane L.) stems, and rapeseed (Brassica napus L.) pistils are presented to illustrate the use of the planing method on fibrous, hard, and delicate materials, respectively.
Scanning electron microscopy studies of protein‐functionalized atomic force microscopy cantilever tips
Authors: Micic Miodrag , Chen Aileen , Leblanc Roger M. , Moy Vincent T. 
Published: June 2010

AbstractProtein‐functionalized atomic force microscopy (AFM) tips have been used to investigate the interaction of individual ligand‐receptor complexes. Herein we present results from scanning electron microscopy (SEM) studies of protein‐functionalized AFM cantilever tips. The goals of this study were (1) to examine the surface morphology of protein‐coated AFM tips and (2) to determine the stability of the coated tips. Based on SEM images, we found that bovine serum albumin (BSA) in solution spontaneously adsorbed onto the surface of silicon nitride cantilevers, forming a uniform protein layer over the surface. Additional protein layers deposited over the initial BSA‐coated surface did not significantly alter the surface morphology. However, we found that avidin‐functionalized tips were contaminated with debris after a series of force measurements with biotinylated agarose beads. The bound debris presumably originated from the transfer of material from the agarose bead. This observation is consistent with the observed deterioration of functional activity as measured in ligand‐receptor binding force experiments.
Glycoproteins and skin‐core structure in Nephila clavipes spider silk observed by light and electron microscopy
Authors: Augsten K. , Mühlig P. , Herrmann C. 
Published: June 2010

AbstractMicroscopical imaging of natural, unstressed draglines or of untreated bulk samples showed two types or threads with diameters of either ∼ 1–2 μm or 4–5 μm, which could be identified as products of the minor or major ampullate glands. The threads had a circular profile in serial cross sections and are surrounded by a thin outer layer of a different material within the section. Such fibrillar configurations were also found in untreated threads or in the same serial sections of transmission electron microscopy (TEM) samples by means of the special technique of laser scanning microscopy. In TEM slides, numerous cavities with the same circular profile were detectable, and the length of these cavities is variable from 40–300 nm. The threads are oriented parallel and twisted around themselves to construct a double thread. In the interface between the two single threads, bridge‐like structures are prominent. The single untreated thread consists of cylindrical fibers with a diameter of approximately 1–1.5 μm. Apparently more than eight fibers are within a thread and each fiber is composed of a great number of fibrils with a diameter of about 150 nm. The surface of threads is coated with a characteristic layer ∼ 150–250 nm thick that contains glycoproteins. These were demonstrated for the first time by labeling with concanavalin A lectin‐gold complex and are dependent on the diameter and length of the thread. The same substances could also be detected inside the single thread. The skin can be removed completely or partially by mechanical treatment, or by washing with phosphate‐buffered saline or trypsin.
Direct measurement of electron beam scattering in the environmental scanning electron microscope using phosphor imaging plates
Authors: Wight Scott A. , Zeissler Cynthia J. 
Published: June 2010

AbstractPhosphor imaging plate technology has made it possible to directly image the distribution of primary beam electrons and scattered electrons in the environmental scanning electron microscope. The phosphor plate is exposed under electron scattering conditions in the microscope chamber. When processed, the electron intensity distribution is displayed as a digital image. The image is a visual representation of the electron probe and skirt and may provide the basis for a more accurate model.
Charge contrast imaging of material growth and defects in environmental scanning electron miscroscopy—linking electron emission and cathodoluminescence
Authors: Griffin Brendan J. 
Published: June 2010

AbstractAn electron‐based technique for the imaging of crystal defect distribution such as material growth histories in non‐ and poorly conductive materials has been identified in the variable pressure or environmental scanning electron microscope. Variations in lattice coherence at the meso‐scale can be imaged in suitable materials. Termed charge contrast imaging (CCI), the technique provides images that correlate exactly with emitted light or cathodoluminescence in suitable materials. This correlation links cathodoluminescence and an electron emission. The specific operating conditions for observation of these images reflect a complex interaction between the electron beam, the positive ions generated by electron‐gas interactions in the chamber, a biased detector, and the sample. The net result appears to be the suppression of all but very near surface electron emission from the sample, probably from of the order of a few nanometres. Consequently, CCI are also sensitive to very low levels of surface contaminants. Successful imaging of internal structures in a diverse range of materials indicate that the technique will become an important research tool.
High‐resolution scanning electron microscopy study of sputtered nanolaminated Ti/TiN multilayers
Authors: le Paven‐Thivet C. , Sant C. , Grillon F. , Houdy P. 
Published: June 2010

AbstractThis work presents the morphologic and structural study of nanolaminated Ti/TiN multilayers using high‐resolution scanning electron microscopy (HR‐SEM), coupled to x‐ray reflectometry (XRR). The multilayers have been deposited by reactive rf‐sputtering on silicon substrates. For large period thickness (λ=40 nm, 10 periods), in XRR, the low number of interfaces makes the interference less structured. An experimental pattern with broad and weakly intense Braggs peaks is obtained, but is difficult to simulate. On the other hand, HR‐SEM observation of cross sections gives excellent pictures of the multilayer, so that precise measurements of the thickness can be achieved: a 42 nm thick period is observed, formed with 17 nm of Ti and with 25 nm of TiN. For small (Ti+TiN) period thickness (λ=2.5 nm, 120 periods), the XRR pattern exhibits intense and narrow Bragg peaks: the number of interfaces is sufficient to structure the interference and an intense signal is obtained. The best fit of simulation is obtained for a 2.6 nm thin period, made of 0.9 nm of Ti and 1.7 nm of TiN. No laminated structure has been observed by cross‐section HR‐SEM observation because its resolution (around 2 nm at 10 kV) is larger than the layer thickness in a period. High‐resolution SEM and XRR are thus two complementary techniques for the routine characterization of multilayers.
Correlative high‐resolution morphologic analysis of the three‐dimensional organization of human chromosomes
Authors: Gobbi Pietro , Thalhammer Stefan , Falconi Mirella , Stark Robert W. , Heckl Wolfgang M. , Mazzotti Giovanni 
Published: June 2010

AbstractA correlative morphologic analysis was carried out on isolated metaphase chromosomes by means of field emission in‐lens scanning electron microscopy (FEISEM) and atomic force microscopy (AFM). Whereas FEISEM provides ultra‐high resolution power and allows the surface analysis of biological structures free of any conductive coating, the AFM allows imaging of biological specimens in ambient as well as in physiologic conditions. The analysis of the same samples was made possible by the use of electrical conductive and light transparent ITO glass as specimen holder. Further preparation of the specimen specific for the instrumentation was not required. Both techniques show a high correlation of the respective morphologic information, improving their reciprocal biological significance. In particular, the biological coat represents a barrier for surface morphologic analysis of chromosome spreads and it is sensitive to protease treatment. The chemical removal of this layer permits high‐resolution imaging of the chromatid fibers but at the same time alters the chromosomal dimension after rehydration. The high‐resolution level, necessary to obtain a precise physical mapping of the genome that the new instruments such as FEISEM and AFM could offer, requires homogeneously cleaned samples with a high grade of reproducibility. A correlative microscopical approach that utilizes completely different physical probes provides complementary useful information for the understanding of the biological, chemical, and physical characteristics of the samples and can be applied to optimize the chromosome preparations for further improvement of the knowledge about spatial genome organization.
Visualization of artificial lignin supramolecular structures
Authors: Mičič Miodrag , Jeremič Milorad , Radotič Ksenija , Mavers Melissa , Leblanc Roger M. 
Published: June 2010

AbstractIn this paper we are presenting the results of our environmental scanning electron microscopy (ESEM) investigation of the lignin model compound—enzymatically polymerized coniferyl alcohol, also known as dehydrogenate polymer (DHP). The goals of this study were to visualize the supramolecular organization of DHP polymer on various substrates, namely graphite, mica, and glass, and to explore the influence of substrate surface properties and associated collective phenomena on the lignin self‐assembled supramolecular structure. Based on results obtained with ESEM, combined with previously published results based on scanning tunneling microscopy (STM) and electron spin resonance (ESR) technique, we looked at lignin structure ranging from a monomer on a fraction of nanometer scale to a large aggregate on a fraction of millimeter scale, therefore using six orders of magnitude range of size. Herein, we are presenting evidence that there are at least four different levels of the supramolecular structure of lignin, and that its supramolecular organization is well dependent on the substrate surface characteristics, such as hydrophobicity, delocalized orbitals, and surface‐free energy.
Atomic force microscopy of human hair
Authors: Swift J. Alan , Smith James R. 
Published: June 2010

AbstractThe atomic force microscope (AFM) was used to investigate the surface architecture of the entire lengths of cleaned human head hairs. Many features previously seen with the scanning electron microscope (SEM) were identified. However, the AFM has provided much greater detail and, in particular, the hair's cuticular surfaces appear not to be as smooth as had been previously supposed. A consistent feature was of step discontinuities or “ghosts” on the scale surfaces. These delineated the original location of each overlying scale before its edge had been chipped away. There was a change in the longitudinal angular presentation of the surfaces about each ghost. This means the distal ends of each cuticle cell have been syn‐thesised in the follicle to be thicker than where that same cuticle cell is bounded on both sides by other cuticle cells. The undamaged outer cuticular surfaces at the root end of each hair were covered everywhere by longitudinal ridges (striations). Where the hair surface was worn, the striations terminated at a scale edge ghost. The ridges were approximately 9 nm high and were in parallel array with a lateral repeat spacing of about 350 nm. The striations are evidently formed on the outer surface of each cuticle cell following earlier contact in the hair follicle with the inner root sheath. The study of stained transverse sections of hairs in the transmission electron microscope (TEM) is suggested as a means for throwing some light on the underlying structure and chemistry of the striations. Finally, our AFM studies have revealed that the surface of the freshly emergent hair gradually changes over a distance of about 20 mm and that the surface of the hair for most of its length is quite different from that near the root. This is likely to be of import to those engaged in the hair toiletries industry.
Electron microscopy of squamous cell carcinoma of the head and neck
Authors: Leek Håkan , Albertsson Maria 
Published: June 2010

AbstractSquamous cell carcinoma of the head and neck carries a bad prognosis. In order to achieve cure, the most important thing to attain is local tumour control. The main therapy available is external radiotherapy, which can be supplemented when necessary, with interstitial radiotherapy, chemotherapy and surgery.In this paper we have evaluated specimens, taken before therapy, from 35 patients with squamous cell carcinoma of the head and neck. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were made. With SEM, the parameters analysed were the amount and appearance of microvilli, filaments, and blood vessels. From TEM, scoring was made of the filaments, desmosomes, nuclei, nucleoli, mitochondria, and blood vessels. Scoring of the samples showed a difference between the group with recurrent disease (n = 10, Group 1) and the group with local tumor control (n = 25, Group 2) in regard to both blood vessels and intracellular filaments. No differences of the nuclei, nucleoli, or the mitochondria were observed.
Correlative light and backscattered electron microscopy of bone —Part II: Automated image analysis
Authors: Goldman Haviva M. , Blayvas Aron , Boyde Alan , Howell Peter G. T. , Clement John G. , Bromage Timothy G. 
Published: June 2010

AbstractDetailed studies of biological phenomena often involve multiple microscopy and imaging modes and media. For bone biology, various forms of light and electron microscopy are used to study the microscopic structure of bone. Integrating information from the different sources is necessary to understand how different aspects of the bone structure interact. To accomplish this, methods were developed to prepare and image thin sections for cor‐relative light microscopy (LM) and backscattered electron imaging in the scanning electron microscope (BSE‐SEM). Images of the same fields of view may then be analyzed for degrees of relationships between specimen features not observed by LM or SEM alone. These methods are applied here to study possible associations between the degree of bone mineralization and pattern of collagen fiber orientation in the mid‐shaft of the human femur. The “relational images” obtained allow us to examine the relationship between these two variables, both objectively and quantitatively.
An anomalous contrast in scanning electron microscopy of insulators: The pseudo‐mirror effect
Authors: Belhaj M. , Jbara O. , Odof S. , Msellak K. , Rau E. I. , Andrianov M. V. 
Published: June 2010

AbstractIn a scanning electron microscope, electron‐beam irradiation of insulators may induce a strong electric field due to the trapping of charges within the specimen interaction volume. On one hand, this field modifies the trajectories of the beam of electrons subsequently entering the specimen, resulting in reduced penetration depth into the bulk specimen. On the other hand, it leads to the acceleration in the vacuum of the emitted secondary electrons (SE) and also to a strong distortion of their angular distribution. Among others, the consequences concern an anomalous contrast in the SE image. This contrast is due to the so‐called pseudo‐mirror effect. The aim of this work is first to report the observation of this anomalous contrast, then to give an explanation of this effect, and finally to discuss the factors affecting it. Practical consequences such as contrast interpretations will be highlighted.
The role of induced contrast in images obtained using the environmental scanning electron microscope
Authors: Toth M. , Phillips M. R. 
Published: June 2010

AbstractGeneration of contrast in images obtained using the environmental scanning electron microscope (ESEM) is explained by interpretation of images acquired using the gaseous secondary electron detector (GSED), ion current, and the Everhart‐Thornley detector. We present a previously unreported contrast component in GSED and ion current images attributed to signal induction by changes in the concentration of positive ions in the ESEM chamber during image acquisition. Changes in positive ion concentration are caused by changes in electron emission from the sample during image acquisition and by a discrepancy between the drift velocities of negative and positive charge carriers in the imaging gas. The proposed signal generation mechanism is used to explain contrast reversal in images produced using the GSED and ion current signals and accounts for discrepancies in contrast observed, under some conditions, in these types of images. Combined with existing models of signal generation in the ESEM, the proposed model provides a basis for correct interpretation of ESEM images.
Immobilization of proteins on self‐assembled monolayers
Authors: Wadu‐Mesthrige Kapila , Amro Nabil A. , Liu Gang‐Yu 
Published: June 2010

AbstractThe immobilization of protein molecules on self‐assembled monolayers (SAM) by physical interactions and chemical bonding has been studied using atomic force microscopy (AFM). The proteins used for our investigation are bovine serum albumin (BSA), lysozyme (LYZ), and normal rabbit immunoglobulin G (IgG). The surfaces are methyl‐, hydroxyl‐, carboxylic acid‐ and aldehyde‐terminated SAMs. We found that BSA and LYZ can be readily immobilized on SAMs at their isoelectric point (IEP). The detailed surface morphology of adsorbed proteins varies with the functionality of the SAMs. The strong hydrophobic interaction at the IEP is attributed to immobilization. If the solution pH is deviated from the IEP, proteins may be attached onto the surface via electrostatic interactions. Covalent binding between the aldehyde‐terminated SAM and the H2N‐groups in the protein results in immobilization of all three proteins. The individual proteins and their orientations on SAMs are clearly resolved from high‐resolution AFM images. The stability and bioactivity of these immobilized proteins are also studied.
Multiphoton confocal microscopy using a femtosecond Cr:Forsterite laser
Authors: Liu Tzu‐Ming , Chu Shi‐Wei , Sun Chi‐Kuang , Lin Bai‐Ling , Cheng Ping‐Chin , Johnson I. 
Published: June 2010

AbstractWith its output wavelength covering the in‐ frared penetrating window of most biological tissues at 1200–1250 nm, the femtosecond Cr:forsterite laser shows high potential to serve as an excellent excitation source for the multiphoton fluorescence microscope. Its high output power, short optical pulse width, high stability, and low dispersion in fibers make it a perfect replacement for the currently widely used Ti: sapphire laser. In this paper, we study the capability of using a femtosecond Cr: forsterite laser in multiphoton scanning microscopy. We have performed the multiphoton excited photolumines‐cence spectrum measurement on several commonly used bioprobes using the 1230 nm femtosecond pulses from a Cr:forsterite laser. Efficient fluorescence can be easily observed in these bioprobes through two‐photon or three‐photon excitation processes. These results will assist in the selection of dichroic beam splitter and band pass filters in a multiphoton microscopic system. We have also performed the autofluorescence spectrum measurement from chlorophylls in live leaves of the plant Arabidopsis thaliana excited by 1230 nm femtosecond pulses from the Cr:forsterite laser. Bright luminescence from chlorophyll, centered at 673 and 728 nm, respectively, can be easily observed. Taking advantage of the bright two‐photon photoluminescence from chlorophyll, we demonstrated the two‐photon scanning paradermal and cross‐sectional images of palisade mesophyll cells in live leaves of Arabidopsis thaliana.
High‐temperature oxidation of nickel and chromium studied with an in‐situ environmental scanning electron microscope
Authors: Schmid B. , Aas N. , Grong Ø. , Ødegård R. 
Published: June 2010

AbstractInvestigations of the morphology of metal oxide scales formed at high temperatures in oxidative environments are usually undertaken after exposure of the samples is completed. In this study, an environmental scanning electron microscope (ESEM) was used as a tool for the in‐situ observation of oxide scale formation. Pure nickel and chromium samples were oxidized at a temperature of 973 K in either pure oxygen or water vapour at a pressure of 667 Pa. The evolution of an oxide scale was followed in‐situ for up to 3 h. The morphology of the developing oxide scales was found to be a function of the metal substrate and the gaseous species. The growth mechanisms of the different metal oxide scales are reviewed and related to the analysed in‐situ images. Emphasis is placed on the relationship between oxidation mechanism and scale morphology. Nickel is seen to oxidise by outward diffusion of nickel probably on oxide grain boundaries when exposed to oxygen. Water vapour changes the scale morphology and a duplex‐type scale arises due to preferential overgrowth. The scale which develops due to chromium oxidation in oxygen is a fine‐grained, thin, and dense layer. In contrast, water vapour leads to whisker growth on chromium and an open, felt‐like structure forms. The applicability of the ESEM to the study of such systems is demonstrated, and its limitations are outlined. The results are encouraging examples of the possibilities which the in‐situ ESEM technique possesses.
Manipulating biological samples for environmental scanning electron microscopy observation
Authors: Tai Susan S. W. , Tang Xue Ming 
Published: June 2010

AbstractBiological samples having different characteristics were observed by environmental scanning electron microscopy (ESEM). The environmental conditions for untreated biological samples was determined by optimizing sample temperature and chamber pressure. When the temperature was at 4° – 6°C and chamber pressure was 5.2–5.9 Torr, the relative humidity in the specimen chamber was about 85%. Under these conditions, the surface features of the sample were completely exposed and did not exhibit charging. The images obtained from the untreated samples at different ESEM conditions were also compared with fixed and coated samples observed under high vacuum.