Elastin-mimetic block copolymers were produced by genetic engineering. Genetically driven synthesis permitted control of the final physiochemical characteristics of the block copolymers. We designed BB and BAB block copolymers in which the A-block was hydrophilic and the B-block was hydrophobic. By designing the copolymers in this manner, it was proposed that they would self-assemble into micellar aggregates that, at high concentration, would form thermoreversible hydrogels. To analyze the three-dimensional fine surface morphology of the copolymers, to the resolution level of a few nanometers, we employed cryo-HRSEM. This method provided vast expanses of the specimen in its frozen hydrated state for survey. In our initial cryo-HRSEM studies, we observed the protein filaments and micelles surrounded by lakes of vitreous ice. Upon examination at low and intermediate magnifications, there was an extensive honeycomb-like filamentous network. To delineate the fine morphology of the hydrogel network at high magnification and to greater depths, we cryoetched away unbound water from the sample surface, in high vacuum, prior to chromium deposition. By using this technique, we were able to visualize for characterization purposes the fine fibril networks formed from the micellar aggregates over the surface of the hydrogel.

Abnormal cilia were demonstrated in the lining epithelial cells of three cases of intraspinal endodermal (bronchogenic) cyst. The changes comprised a wide spectrum of ultrastructural abnormalities, including (a) cilia with abnormal axonemal microtubules, (b) swollen cilia, (c) compound cilia with or without excessive ciliary matrix, (d) naked cilia without limiting membrane, and (e) intracytoplasmic cilia and aggregates of microtubules. Of these, compound cilia and swollen cilia were most common. Cilia with dynein arm deficiency were not observed. Ciliary abnormalities found in the present study were very similar to those described in the bronchial epithelium of various diseases. The present findings suggest that the lining epithelium of intraspinal endodermal cyst shares similar ciliogenesis and susceptibility to abnormal ciliary formation as that of the bronchial epithelium.

We employed multiphoton laser scanning microscopy (MPLSM) to image changes in mitochondrial distribution in living rhesus monkey embryos. This method of imaging does not impair development; thus, the same specimen can be visualized multiple times at various developmental stages. Not only does this increase the amount of information that can be gathered on a single specimen but it permits the correlation of early events with subsequent development in the same specimen. Here we demonstrate the utility of MPLSM for determining changes in mitochondrial organization at various developmental stages and show that rhesus zygotes possess a distinct accumulation of mitochondria between the pronuclei prior to syngamy. We present evidence that suggests that this pronuclear accumulation may be positively correlated with development to the blastocyst stage—in the same embryo—thereby illustrating how MPLSM can be used to correlate cellular dynamics of primate oocytes and early embryos with their developmental potential. Understanding the relationship between mitochondrial distribution and the subsequent development of mammalian embryos, particularly primates, will increase our ability to improve embryo culture technologies, including those used for human assisted reproduction.

We present high-precision measurements of pure element stable isotope pairs that demonstrate mass has no influence on the backscattering of electrons at typical electron microprobe energies. The traditional prediction of average backscatter intensities in compounds was pragmatically based on elemental mass fractions. Our isotopic measurements establish that this approximation has no physical basis. We propose an alternative model to mass fraction averaging, based on the number of electrons or protons, termed “electron fraction,” which predicts backscatter yield better than mass fraction averaging. We also present an improved backscatter (electron loss) factor based on a modified electron fraction average for the ZAF atomic number correction that provides a significant analytical improvement, especially where large atomic number corrections are required.

The focused ion beam (FIB) tool has been successfully used as both a stand alone analytical instrument and a means to prepare specimens for subsequent analysis by SEM, TEM, SIMS, XPS, and AUGER. In this work, special emphasis is given to TEM specimen preparation by the FIB lift-out technique. The fundamental ion/solid interactions that govern the FIB milling process are examined and discussed with respect to the preparation of electron transparent membranes. TRIM, a Monte Carlo simulation code, is used to physically model variables that influence FIB sputtering behavior. The results of such computer generated models are compared with empirical observations in a number of materials processed with an FEI 611 FIB workstation. The roles of incident ion attack angle, beam current, trench geometry, raster pattern, and target-material-dependent removal rates are considered. These interrelationships are used to explain observed phenomena and predict expected milling behaviors, thus increasing the potential for the FIB to be used more efficiently with reproducible results.

The boundary parameters between contacting spherical bcc-Fe particles have been characterized with the Large Angle Convergent Beam Electron Diffraction (LACBED) technique. The average accuracy of measurements can reach 0.07°. The rotation parameters are interpreted using matrix algebra and evaluated according to the CSL model. The deviation between the experimental results and the reference misorientations given in the CSL model is determined. It is possible to reveal preferential misorientations between irregularly shaped particles with a size less than 100 nm. The method can be applied to nanoparticles and nanocrystalline materials with a wide range of grain orientations, and it is possible to modify it into an automatic method for TEM measurements.

The article compares the relative stability of MCM-41 and related mesoporous materials in electron beam at an accelerating voltage of 100–300 kV. The work encountered in electron microscopy presents a comparison with similar research that has been carried out on nonporous and microporous silicates, especially α-quartz and zeolite Y. The trends in stability are analyzed, classifying the effects of sample preparation, organic and inorganic moieties, and electron accelerating voltage on beam stability. A higher synthesis temperature, the use of an acid catalyst in the synthesis, and the presence of additional organic or inorganic material within the channels were all found to stabilize these materials. The dose required to completely disrupt the structure increased with accelerating voltage for nearly all samples, suggesting a primarily radiolytic damage mechanism. The exception, MCM-41 containing nanometer-sized titania particles in its channels, was found to be almost insensitive to accelerating voltage.