Summary: The present communication reports the first use of electron tomography in reconstructing the three‐dimensional morphology in thermoplastic elastomer blends. The blends investigated were dynamically vulcanized blends of ethylene‐propylene‐diene (EPDM) rubber/poly(propylene)/oil and polystyrene‐block‐(ethylene‐co‐butylene)‐block‐polystyrene (SEBS)/poly(propylene)/oil. An easy identification of blend morphology could be carried out at blend compositions, where conventional transmission electron microscopic imaging gives misleading information. This technique gives a higher resolution than any other microscopic technique, and is applicable to blends with dispersed as well as co‐continuous morphologies.
Example of a tomographic model of partially co‐continuous SEBS phases in a SEBS/PP/oil thermoplastic blend. Only the contours of the SEBS phase are shown. 相似文献
By using mass spectrometry to analyze the atomic and molecular secondary ions that are emitted from a solid surface when bombarded with ions, one obtains detailed information about the chemical composition of the surface. A time-of-flight mass spectrometer is especially suitable for the analysis of secondary ions because of its high transmission, high mass resolution, and ability to detect ions of different masses simultaneously. By using a finely focused primary ion beam it is also possible to analyze microareas and generate surface images with a lateral resolution of 0.1 μm or less. Static time-of-flight secondary ion mass spectrometry (TOF-SIMS) allows monolayer imaging and local analysis of monolayers with high sensitivity, a wide mass range, high mass resolution, and high lateral resolution. Besides information on elements and isotopes, the technique yields direct information on the molecular level and can also be used to analyze surface species of high molecular mass that are thermally unstable and cannot be vaporized. The method can be applied to practically all types of materials and sample forms, including insulators in particular. In this article the basic principles of TOF-SIMS are explained, and its analytical capabilities for both large area and imaging applications are illustrated by examples. These include silicon surfaces (both uniform and structured), thermally unstable organic molecules on surfaces, synthetic polymers, and synthetically prepared molecular surface films, particles, and fibers. Emitted neutral particles can also be analyzed by postionization with a laser, and the possibilities of this technique are discussed. 相似文献
Two poly(quinoxaline‐2,3‐diyl) copolymers bearing miscibility‐enhancing 8‐chlorooctyloxy and (S)‐2‐methylbutoxy or n‐butoxy side chains were synthesized. After annealing in CHCl3 vapor, a polymer‐blend film of these copolymers exhibited selective reflection of right‐handed circularly polarized light (CPL) in the visible region. The handedness of the CPL reflected was completely inverted upon annealing of the film in THF vapor. Annealing in n‐hexane vapor resulted in the phase separation of the polymer blend, which turned the selective reflection off. This three‐way‐switchable reflection, that is, reflection of right‐handed or left‐handed CPL, together with an OFF state, could be observed visually through right‐ and left‐handed CPL filters. 相似文献
Three‐dimensional (3D) reticular SnO2 thin films deposited on copper and stainless steel substrates were prepared by the electrostatic spray deposition (ESD) technique. The 3D reticular SnO2 film exhibit a high reversible capacity near 300 mAh g?1 up to the 50th cycle.相似文献
Preferred protonation : Does electrospray ionization mass spectrometry produce gas‐phase or liquid‐phase structures? The preferred protonation site in p‐aminobenzoic acid depends upon the medium, and the structure of its conjugate acid varies with the solvent used during spraying.
Living tissues or organ modules consist of different types of highly organized cells and extracellular matrices (ECMs) in a hierarchical manner, such as the multilayered structure of blood vessels and the radial structures of hepatic lobules. Due to animal examinations being banned in the EU since 2013 and a shortage in the demand for tissue repair or organ transplantation, the creation of artificial 3D tissues possessing specific structures and functions similar to natural tissues are key challenges in tissue engineering. To date, we have developed a simple but unique bottom‐up approach, a hierarchical cell manipulation technique, with a nanometer‐sized ECM matrix consisting of fibronectin (FN) and gelatin (G) on cell surfaces. About 10 nm thick FN/G ECM films on cell surfaces were coated successfully by using layer‐by‐layer coating methodology. Various 3D constructs with higher cell density with different types of cells were successfully constructed. In addition to the construction of tissues with higher cell densities, other tissues, such as cartilage or skin tissues, with different cell densities are also important tissue models for tissue engineering and pharmaceutical industries. Thus, we recently developed other methodologies, the collagen coating method and multiple coating method, to fabricate micrometer‐sized level ECM layers on cell surfaces. Various micro‐ or millimeter‐sized 3D constructs with lower cell densities were constructed successfully. By using these two methods, cell distances in 2D or 3D views can be controlled by different thicknesses of ECM layers on cell surfaces at the single‐cell level. Both FN/G and the collagen coating method resulted in homogenous 3D tissues with a controlled layer numbers, cell type, cell location, and properties; these will be promising to achieve different goals in tissue engineering.
The powerful nature of the secondary ion mass spectrometry (SIMS) technique was explored in order to analyse very thin surface layers that were self-assembled on steel material from acidic solution. These surface layers are adsorbed corrosion inhibitors. The SIMS technique proved useful to characterise the molecular structure and homogeneity of thin surface layers in the nanometre range of specific analytes on the metallic substrate. Using SIMS, the thermal stability of these layers was further investigated and the desorption energy at a certain temperature was determined, where special attention was devoted to the method’s static limit. In order to compare, and for certain cases emphasise, the benefits gained by using SIMS in such surface analysis compared with the X-ray photoelectron spectroscopy (XPS) method, the same samples were also analysed by means of the latter. XPS is usually considered to be the most powerful analytical tool in surface analysis studies, but, as shown herein, it has certain limitations compared to SIMS. Finally, the surface topography was investigated by employing atomic force microscopy (AFM) in order to carry out a comprehensive surface analysis.
The emission of atomic and complex nitrogen ions, which are the main impurity determining the n type conduction of silicon carbide, is investigated. It is shown that, among all the secondary ions of the CxN and SixN kind (x = 0, 1, 2, 3), the 26(CN)– fragment exhibits the highest ion yield. The use of an ion peak with a specified mass as an analytical signal provides a detection limit for nitrogen in SiC at a level of 1016 cm–3. This result is attained in measurements at high mass resolution (M/M = 7500, interference peak 26(13C2)–). 相似文献
For the first time, grazing incidence small‐angle X‐ray scattering (GISAXS) analysis is used to characterize the morphology of TiO2 thin films grown by glancing angle physical vapor deposition (GLAD). According to cross‐section scanning electron microscopy (SEM) images, the films consist of near isotilted TiO2 columns of different length and width depending on film thickness. The obtained GISAXS patterns show a characteristic asymmetry with respect to the incidence plane, which is associated with the tilted geometry of the TiO2 columns. The patterns also show the existence of two populations of columns in these GLAD‐TiO2 films. The population of the thinnest columns appears related to the first grown layer and is common for all the films investigated, while the second population of columns grows with the thickness of the films and has been related to wider columns formed by shadowing at the expense of the initially formed columns.相似文献
Secondary ion mass spectrometry (SIMS) is generally used in imaging the isotopic composition of various materials. It is becoming increasingly popular in biology, especially for investigations of cellular metabolism. However, individual proteins are difficult to identify in SIMS, which limits the ability of this technology to study individual compartments or protein complexes. We present a method for specific protein isotopic and fluorescence labeling (SPILL), based on a novel click reaction with isotopic probes. Using this method, we added 19F‐enriched labels to different proteins, and visualized them by NanoSIMS and fluorescence microscopy. The 19F signal allowed the precise visualization of the protein of interest, with minimal background, and enabled correlative studies of protein distribution and cellular metabolism or composition. SPILL can be applied to biological systems suitable for click chemistry, which include most cell‐culture systems, as well as small model organisms. 相似文献
Recent studies suggest that the H1 subunit of the carbohydrate recognition domain (H1CRD) of the asialoglycoprotein receptor
is used as an entry site into hepatocytes by hepatitis A and B viruses and Marburg virus. Thus, molecules binding specifically
to the CRD might exert inhibition towards these diseases by blocking the virus entry site. We report here the identification
of the epitope structure of H1CRD to a monoclonal antibody by proteolytic epitope excision of the immune complex and high-resolution
MALDI-FTICR mass spectrometry. As a prerequisite of the epitope determination, the primary structure of the H1CRD antigen
was characterised by ESI-FTICR-MS of the intact protein and by LC-MS/MS of tryptic digest mixtures. Molecular mass determination
and proteolytic fragments provided the identification of two intramolecular disulfide bridges (seven Cys residues), and a
Cys-mercaptoethanol adduct formed by treatment with β-mercaptoethanol during protein extraction. The H1CRD antigen binds to
the monoclonal antibody in both native and Cys-alkylated form. For identification of the epitope, the antibody was immobilized
on N-hydroxysuccinimide (NHS)-activated Sepharose. Epitope excision and epitope extraction with trypsin and FTICR-MS of affinity-bound
peptides provided the identification of two specific epitope peptides (5–16) and (17–23) that showed high affinity to the
antibody. Affinity studies of the synthetic epitope peptides revealed independent binding of each peptide to the antibody. 相似文献
Sphingomyelin synthase (SMS) produces sphingomyelin and diacylglycerol from ceramide and phosphatidylcholine. It plays an important role in cell survival and apoptosis, inflammation, and lipid homeostasis, and therefore has been noticed in recent years as a novel potential drug target. In this study, we combined homology modeling, molecular docking, molecular dynamics simulation, and normal mode analysis to derive a three‐dimensional structure of human sphingomyelin synthase (hSMS1) in complex with sphingomyelin. Our model provides a reasonable explanation on the catalytic mechanism of hSMS1. It can also explain the high selectivity of hSMS1 towards phosphocholine and sphingomyelin as well as some other known experimental results about hSMS1. Moreover, we also derived a complex model of D609, the only known small‐molecule inhibitor of hSMS1 so far. Our hSMS1 model may serve as a reasonable structural basis for the discovery of more effective small‐molecule inhibitors of hSMS1. 相似文献
Three‐dimensional (3D) ordered arrays of human immunoglobulin G (IgG) were fabricated using well‐defined full‐length antibody–polymer conjugates (APCs). The conjugates were prepared through a two‐step sequential click approach with a combination of oxime ligation and strain promoted alkyne–azide cycloaddition. They were able to self‐assemble into lamellar nanostructures with alternating IgG and poly(N ‐isopropylacrylamide) (PNIPAM) nanodomains. As a proof‐of‐concept, these materials were fabricated into thin films and their specific binding ability was tested. The nanostructure not only improves the packing density and the proper orientation of the IgG, but also provides nanochannels to facilitate substrate transport. 相似文献