A test of the qualities of polarizing filters was performed for a set of specimens including a bulk Nicol prism, standard polaroids, and special polyvinyl alcohol (PVA)-iodine thin-film filters coated on both sides by vertically oriented carbon nanotubes. The residual transmission of polarizing filters depending on the incidence angle of polarized light was examined in detail. The superior quality of polarizing film filters treated with carbon nanotubes was found. This fact allows us to propose a new application for polarizing films with carbon nanotubes for a polarizing cover glass. In such a way the cover glass may serve as an analyzer in a light polarizing microscope. Some features of optical scheme arrangement for the polarizing technique are discussed. The polarizing cover glass allows elimination of depolarization of light, which is inserted in a microscope objective. Test results of the proposed polarizing technique attest to the efficiency of using the polarizing cover glass. The new scheme for polaroid arrangement shows image-contrast enhancement by several percent in comparison with the standard layout.

The development of the helium ion microscope (HIM) enables the imaging of both hard, inorganic materials and soft, organic or biological materials. Advantages include outstanding topographical contrast, superior resolution down to <0.5 nm at high magnification, high depth of field, and no need for conductive coatings. The instrument relies on helium atom adsorption and ionization at a cryogenically cooled tip that is atomically sharp. Under ideal conditions this arrangement provides a beam of ions that is stable for days to weeks, with beam currents in the order of picoamperes. Over time, however, this stability is lost as gaseous contamination builds up in the source region, leading to adsorbed atoms of species other than helium, which ultimately results in beam current fluctuations. This manifests itself as horizontal stripe artifacts in HIM images. We investigate post-processing methods to remove these artifacts from HIM images, such as median filtering, Gaussian blurring, fast Fourier transforms, and principal component analysis. We arrive at a simple method for completely removing beam current fluctuation effects from HIM images while maintaining the full integrity of the information within the image.

This paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam. Direct ray tracing simulation is used to illustrate how a three-stage core lens corrector can be used to eliminate the first- and second-order geometric aberrations of an electric Einzel objective lens.

Thin-film phase plates (PPs) have become an interesting tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense electron-beam illumination. Recent investigations have focused on the search for alternative materials with an improved material stability. This work presents thin-film PPs fabricated from metallic glass alloys, which are characterized by a high electrical conductivity and an amorphous structure. Thin films of the zirconium-based alloy Zr65.0Al7.5Cu27.5 (ZAC) were fabricated and their phase-shifting properties were evaluated. The ZAC film was investigated by different TEM techniques, which reveal beneficial properties compared with amorphous carbon PPs. Particularly favorable is the small probability for inelastic plasmon scattering, which results from the combined effect of a moderate inelastic mean free path and a reduced film thickness due to a high mean inner potential. Small probability plasmon scattering improves contrast transfer at high spatial frequencies, which makes the ZAC alloy a promising material for PP fabrication.

Resist lithography is an important microfabrication technique in the electronics industry. In this, patterns are transferred by irradiation onto a photosensitive polymer. SU-8 has emerged as a favorite photoresist for High Aspect Ratio (HAR) lithography, showing high chemical and mechanical stability and biocompatibility. Unfortunately, its poor adhesion to substrates is a drawback, with possible solutions being the use of low-viscosity SU-8, surface modification with a low molecular weight adsorbate like hexamethyldisilazane (HMDS), or a commercial adhesion promotion reagent. However, HMDS and the commercial reagent require surface dehydration and/or curing, and a modified form of SU-8 is not always desirable. Here, we demonstrate the use of a water-soluble, amine-containing polymer, polyallylamine (PAAm), which spontaneously adsorbs to silica surfaces, as a simple, easy-to-apply, and reactive adhesion promoter for SU-8. Conditions for the use of PAAm are explored, and the resulting materials are characterized by X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and wetting.

The resolution of high-resolution transmission electron microscopes (TEM) has been improved down to subangstrom levels by correcting the spherical aberration (Cs) of the objective lens, and the information limit is thus determined mainly by partial temporal coherence. As a traditional Young’s fringe test does not reveal the true information limit for an ultra-high-resolution electron microscope, new methods to evaluate temporal coherence have been proposed based on a tilted-beam diffractogram. However, the diffractogram analysis cannot be applied when the nonlinear contribution becomes significant. Therefore, we have proposed a method based on the three-dimensional (3D) Fourier transform (FT) of through-focus TEM images, and evaluated the performance of some Cs-corrected TEMs at lower voltages. In this report, we generalize the 3D FT analysis and derive the 3D transmission cross-coefficient. The profound difference of the 3D FT analysis from the diffractogram analysis is its capability to extract linear image information from the image intensity, and further to evaluate two linear image contributions separately on the Ewald sphere envelopes. Therefore, contrary to the diffractogram analysis the 3D FT analysis can work with a strong scattering object. This is the necessary condition if we want to directly observe the linear image transfer down to a few tens of picometer.

A prototype Peltier thermoelectric cooling unit has been constructed to cool a cold finger on an electron microprobe. The Peltier unit was tested at 15 and 96 W, achieving cold finger temperatures of −10 and −27°C, respectively. The Peltier unit did not adversely affect the analytical stability of the instrument. Heat conduction between the Peltier unit mounted outside the vacuum and the cold finger was found to be very efficient. Under Peltier cooling, the vacuum improvement associated with water vapor deposition was not achieved; this has the advantage of avoiding severe degradation of the vacuum observed when warming up a cold finger from liquid nitrogen (LN2) temperatures. Carbon contamination rates were reduced as cooling commenced; by −27°C contamination rates were found to be comparable with LN2-cooled devices. Peltier cooling, therefore, provides a viable alternative to LN2-cooled cold fingers, with few of their associated disadvantages.

The nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3–SiO2, Bi:GeO2–SiO2, Bi:Al2O3–GeO2–SiO2, and Bi:P2O5–Al2O3–GeO2–SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers. The bismuth concentration of 0.0048±0.0006 at% is directly measured in aluminosilicate optical fibers with effective laser generation (slope efficiency of 27% at room temperature).

Characterization of the topmost surface of biomaterials is crucial to understanding their properties and interactions with the local environment. In this study, the oxide layer microstructure of plasma-modified 316L stainless steel (SS316L) samples was analyzed by a combination of electron backscatter diffraction and electron channeling contrast imaging using low-energy incident electrons. Both techniques allowed clear identification of a nano-thick amorphous oxide layer, on top of the polycrystalline substrate, for the plasma-modified samples. A methodology was developed using Monte Carlo simulations combined with the experimental results to estimate thickness of the amorphous layer for different surface conditions. X-ray photoelectron spectroscopy depth profiles were used to validate these estimations.

A corrosion product rarely reported in the literature has been found on the copper support of three miniature paintings of the 17th and 18th centuries. This product, which has been identified as dicoppertrihydroxyformate (Cu2(OH)3HCOO), is an unusual basic copper formate found on copper artifacts. The identification and characterization of dicoppertrihydroxyformate was carried out directly over the corroded surface of the objects, using a nondestructive approach, which combines the integrated use of various microanalytical techniques. Using this approach, it was possible to obtain a set of new reference data about the natural form of Cu2(OH)3HCOO, that will enable its unambiguous identification in other similar objects. In this work, the probable causes that may have contributed to its formation are also discussed.

Resin composite materials that are used to restore tooth cervical lesions associated with gingival recessions can hamper healing after root coverage surgeries. This study evaluates the in vitro cytotoxic effect of five resin composites (two commercial and three experimental) on oral mesenchymal stem cells (MSCs) and the persistence of stemness properties in high passage MSCs. Sorption and solubility tests were made for all materials. MSCs were isolated from re-entry palatal and periodontal granulation tissues and were characterized and cultured on composite discs. Cytotoxicity of the materials was evaluated by the Alamar Blue viability test, by Paul Karl Horan (PKH) labeling, and by immunocytochemical staining for actin. Water and saliva sorption and solubility data revealed that two of the experimental materials behaved comparable with the marketed resin composites. The Alamar Blue viability test shows that both cell lines grew well on composite discs that seemed to induce no apparent toxic effects. No signs of disruption of cytoskeleton organization was seen. Experimental resin composites can be recommended for further investigation for obtaining approval for use. The standard minimal criteria were fulfilled for high passage MSCs. Palatal tissue regains its regenerative properties in terms of MSC presence in the re-entry area after 6 months of healing.

The aim of this research was to assess the ability of amalgam restorations to induce amorphous mineral precipitation at the caries-affected dentin substrate. Sound and caries-affected dentin surfaces were subjected to both Zn-free and Zn-containing dental amalgam restorations. Specimens were submitted to thermocycling (100,000 cycles/5°C–55°C, 3 months). Dentin surfaces were studied by atomic force microscopy (nanoroughness), X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive analysis, for physical and morphological surface characterization. Zn-containing amalgam placement reduced crystallinity, crystallite size, and grain size of calcium phosphate crystallites at the dentin surface. Both microstrain and nanoroughness were augmented in caries-affected dentin restored with Zn-containing amalgams. Caries-affected dentin showed the shortest mineral crystallites (11.04 nm), when Zn-containing amalgams were used for restorations, probably leading to a decrease of mechanical properties which might favor crack propagation and deformation. Sound dentin restored with Zn-free amalgams exhibited a substantial increase in length of grain particles (12.44 nm) embedded into dentin crystallites. Zn-containing amalgam placement creates dentin mineralization and the resultant mineral was amorphous in nature. Amorphous calcium phosphate provides a local ion-rich environment, which is considered favorable for in situ generation of prenucleation clusters, promotong further dentin remineralization.

Angstrom resolution images of human tooth enamel (HTE) crystallites were obtained using aberration-corrected high-resolution transmission electron microscopy and atomic-resolution scanning transmission electron microscopy in the modes of bright field, annular dark field, and high-angle annular dark-field. Images show that the central dark line (CDL) defect observed around the center of the HTE crystals is a site for caries formation in the HTE and has a thickness of ~0.2 nm. Results also suggest that the CDL goes through one of the OH− planes.

Although the rat model of mammary tumors chemically induced by N-methyl-N-nitrosourea (MNU) has been frequently used by several research teams, there is a lack of ultrastructural studies in this field. The main aim of this work was to perform an ultrastructural characterization of MNU-induced mammary tumors in female rats. Some alterations previously reported in human mammary tumors, such as nucleus size and shape, accumulation of heterochromatin in the perinuclear region, and interdigitating cytoplasmic processes between cancer cells were also observed in MNU-induced mammary tumors. Although a low number of samples were analyzed by transmission electron microscopy in the present study, we consider that it may contribute to a better understanding of MNU-induced mammary carcinogenesis in a rat model. The ultrastructural characteristics of the two most frequently diagnosed mammary carcinomas described in the present work can be useful to differentiate them from other histological patterns. In addition, the loss of cytoplasm in neoplastic cells and formation of vacuoles were described.

Asbestos bodies are the histological hallmarks of asbestos exposure. Both conventional and advanced techniques are used to evaluate abundance and composition in histological samples. We previously reported the possibility of using synchrotron X-ray fluorescence microscopy (XFM) for analyzing the chemical composition of asbestos bodies directly in lung tissue samples. Here we applied a high-performance synchrotron X-ray fluorescence (XRF) set-up that could allow new protocols for fast monitoring of the occurrence of asbestos bodies in large histological sections, improving investigation of the related chemical changes. A combination of synchrotron X-ray transmission and fluorescence microscopy techniques at different energies at three distinct synchrotrons was used to characterize asbestos in paraffinated lung tissues. The fast chemical imaging of the XFM beamline (Australian Synchrotron) demonstrates that asbestos bodies can be rapidly and efficiently identified as co-localization of high calcium and iron, the most abundant elements of these formations inside tissues (Fe up to 10% w/w; Ca up to 1%). By following iron presence, we were also able to hint at small asbestos fibers in pleural spaces. XRF at lower energy and at higher spatial resolution was afterwards performed to better define small fibers. These analyses may predispose for future protocols to be set with laboratory instruments.

In this work, we report that polarization second harmonic generation (PSHG) microscopy, commonly used in biomedical imaging, can quantitatively discriminate naturally aged from fresh starch-based glues used for conservation or restoration of paintings, works of art on paper, and books. Several samples of fresh and aged (7 years) flour and starch pastes were investigated by use of PSHG. In these types of adhesives, widely used in cultural heritage conservation, second harmonic generation (SHG) contrast originates primarily from the starch granules. It was found that in aged glues, the starch SHG effective orientation (SHG angle, θ) shifts to significantly higher values in comparison to the fresh granules. This shift is attributed to the different degree of granule hydration between fresh and aged adhesives. Thus noninvasive high-resolution nonlinear scattering can be employed to detect and quantify the degree of deterioration of restoration adhesives and to provide guidance toward future conservation treatments.

The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60–180 min), formic acid concentration (80–95%), temperature (60–80°C), and hydrogen peroxide concentration (2–4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

Residues like sewage sludge and vinasse have been reused as agricultural fertilizers, but they also present a potential to contaminate soils. Diplopods have been considered excellent bioindicators of soil contamination. In the present study, Rhinocricus padbergi were used to assess toxicity in samples of sewage sludge, biosolids, and sugarcane vinasse. The behavioral analysis, mortality rate, and histological, histochemical, and ultrastructural analyses of the midgut of diplopods were the parameters evaluated. Behaviorally, some diplopods avoided burying themselves after 30 days in soil with biosolid or vinasse. Besides, certain residue combinations were able to cause death of all individuals between 60 and 90 days of exposure. The main tissue responses were significant brush border thickening, induction of epithelial renovation, clustering of hemocytes, accumulation of cytoplasmic granules in hepatic cells, hepatic cells with heteropycnotic nuclei, and cytoplasmic degradation. Alterations were observed at various levels among treatments with different samples and exposure times. Ultrastructural analysis revealed elongation of microvilli coated with a layer of an amorphous substance, resulting in a thicker brush border as observed in the histological analysis. After 30 days of exposure, animals showed an accumulation of spherocrystals in hepatic cells and high absorption of substances, based on the elongation of microvilli. Results obtained in the chemical analysis and the behaviors observed in diplopods suggest that animals processed the residues. Therefore, caution should be exercised in the disposal of these residues in agriculture.