Interaction of maize zein with wheat gluten in composite dough and bread as determined by confocal laser scanning microscopy

Protein body-free maize zein, when mixed at 35 degrees C (above its glass transition temperature range), significantly (p < 0.01) improved the rheological and leavening properties of sorghum-wheat composite flour dough, resulting in improved loaf volume. Confocal laser scanning microscopy was used to observe the structure of zein fibrils and the interaction between zein and gluten proteins in the composite dough and bread systems. Autofluorescence and immunolocalization techniques were used to locate gluten and zein, respectively. Optical sections were collected every 0.4 microm through the samples and digitally processed to produce reconstructed three-dimensional images. Results showed that zein fibrils form an outer layer that intermittently coats the gluten networks, thereby strengthening them. This type of microstructure is able to withstand the pressure exerted by gas cell expansion during yeast fermentation to increase loaf volume.     

Imaging connected porosity of crystalline rock by contrast agent‐aided X‐ray microtomography and scanning electron microscopy

We set out to study connected porosity of crystalline rock using X‐ray microtomography and scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDS) with caesium chloride as a contrast agent. Caesium is an important radionuclide regarding the final deposition of nuclear waste and also forms dense phases that can be readily distinguished by X‐ray microtomography and SEM‐EDS. Six samples from two sites, Olkiluoto (Finland) and Grimsel (Switzerland), where transport properties of crystalline rock are being studied in situ, were investigated using X‐ray microtomography and SEM‐EDS. The samples were imaged with X‐ray microtomography, immersed in a saturated caesium chloride (CsCl) solution for 141, 249 and 365 days and imaged again with X‐ray microtomography. CsCl inside the samples was successfully detected with X‐ray microtomography and it had completely penetrated all six samples. SEM‐EDS elemental mapping was used to study the location of caesium in the samples in detail with quantitative mineral information. Precipitated CsCl was found in the connected pore space in Olkiluoto veined gneiss and in lesser amounts in Grimsel granodiorite. Only a very small amount of precipitated CsCl was observed in the Grimsel granodiorite samples. In Olkiluoto veined gneiss caesium was found in pinitised areas of cordierite grains. In the pinitised areas caesium was found in notable excess compared to chloride, possibly due to the combination of small pore size and negatively charged surfaces. In addition, elevated concentrations of caesium were found in kaolinite and sphalerite phases. The findings concerning the location of CsCl were congruent with X‐ray microtomography.     

Polymerization shrinkage and porosity profile of dual cure dental resin cements with different adhesion to dentin mechanisms

This research aims to probe the porosity profile and polymerization shrinkage of two different dual cure resin cements with different dentin bonding systems. The self‐adhesive resin cement RelyX U200 (named RU) and the conventional Allcem Core (named AC) were analyzed by x‐ray microtomography (μCT) and Scanning Electron Microscopy (SEM). Each cement was divided into two groups (n = 5): dual‐cured (RUD and ACD) and self‐cured (RUC and ACC). μCT demonstrated that the method of polymerization does not influence the porosity profile but the polymerization shrinkage. Fewer concentration of pores was observed for the conventional resin cement (AC), independently the method used for curing the sample. In addition, SEM showed that AC has more uniform surface and smaller particle size. The method of polymerization influenced the polymerization shrinkage, since no contraction for both RUC and ACC was observed, in contrast with results from dual‐cured samples. For RUD and ACD the polymerization shrinkage was greater in the lower third of the sample and minor in the upper third. This mechanical behavior is attributed to the polymerization toward the light. µCT showed to be a reliable technique to probe porosity and contraction due to polymerization of dental cements.     

Application of X‐ray microcomputed tomography in the characterization of irradiated nuclear fuel and material specimens

X‐ray microcomputed tomography (μCT) was applied in characterizing the internal structures of a number of irradiated materials, including carbon‐carbon fibre composites, nuclear‐grade graphite and tristructural isotropic‐coated fuel particles. Local cracks in carbon‐carbon fibre composites associated with their synthesis process were observed with μCT without any destructive sample preparation. Pore analysis of graphite samples was performed quantitatively, and qualitative analysis of pore distribution was accomplished. It was also shown that high‐resolution μCT can be used to probe internal layer defects of tristructural isotropic‐coated fuel particles to elucidate the resulting high release of radioisotopes. Layer defects of sizes ranging from 1 to 5 μm and up could be isolated by tomography. As an added advantage, μCT could also be used to identify regions with high densities of radioisotopes to determine the proper plane and orientation of particle mounting for further analytical characterization, such as materialographic sectioning followed by optical and electron microscopy. In fully ceramic matrix fuel forms, despite the highly absorbing matrix, characterization of tristructural isotropic‐coated particles embedded in a silicon carbide matrix was accomplished using μCT and related advanced image analysis techniques.     

Monte Carlo analysis of the detection of clay occlusion of respirable quartz particles using multiple voltage scanning electron microscopy

The electron incident-energy dependence of the relative intensities of Al and Si x-rays produced in a respirable-sized quartz particle by scanning electron microscopy is sensitive to the inhomogeneity of the distribution of Al and Si in the particle. Realistic Monte Carlo calculations of this energy dependence validate the proposal to use this effect for the detection of particles in which an aluminosilicate coating occludes the surface of a silica core.     

Secondary and backscattered electron imaging of weathered chromian spinel

Secondary (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.     

Tribological performances of heterocyclic‐containing ether and/or thioether as additives in the synthetic diester

The load‐carrying capacity, wear and friction properties of 2‐octoxyl methylthio‐benzothiazole (DEOY) and 2‐dodecylthio methylthio‐benzothiazole (DEMB) added to a synthetic lubricant (diester) were evaluated using a four‐ball test machine. The results indicate that the two compounds added to the diester possess good load‐carrying capacities and excellent anti‐wear and friction reduction properties. The thermal stability of the two compounds under nitrogen atmosphere was investigated by thermogravimetric analysis (TGA). It was found that the compounds DEOY and DEMB possess excellent thermal stability. The surface topography of the rubbed surface was investigated with scanning electron microscopy, the elemental chemical nature of the anti‐wear films generated on steel counterface were investigated with X‐ray photoelectron spectroscopy. Copyright © 2009 John Wiley & Sons, Ltd.     

Use of X-ray micro tomography to study the microstructure of loose-packed and compacted milk powders

The use of X-rays to evaluate food microstructure has developed considerably in recent years. In this work we used X-ray micro tomography (XMT) to visualize the microstructure of loose-packed and compacted samples of spray-dried skim milk powder (SMP) and whole milk powder (WMP) and to quantify the proportion of both interstitial and occluded air voids in each sample. Visual scrutiny of the acquired XMT images showed details of the microstructure of the milk powders such as the spherical morphology of the particles, the size of the particles and internal air voids of various sizes. Within loose-packed powders, the proportion of air voids was higher (13% average) in WMP than in SMP. This was reversed in the compacted powders, in which the proportion of air voids was higher in SMP. The disparity in the proportion of air voids in both loose-packed and compacted samples of SMP and WMP was attributed to the size, shape and surface properties of the particles.     

Study of cellular architecture and micromechanical properties of cuajilote fruits (Parmentiera edulis D.C.) using different microscopy techniques

The cuajilote (Parmentiera edulis D.C.) tree produces fibrous fruits with a high content of lignocellulosic compounds. However, this fruit and their fibers have been scarcely studied. For this reason, an integral study of their cellular architecture, physicochemical, micromechanical, and structural properties in two maturity stages were carried out. Physicochemical tests, light, confocal and electron microscopy, microindentation, and X‐ray diffraction were used for the characterization of fruit and their fibers. Chemical analysis showed that the unripe fruits have the highest cellulose content (42.17%), but in ripe fruit the cellulose content decreases (32.76%) while lignin content increases from 35.26 to 40.79%, caused by the lignification of the sclerenchyma fibers. Microstructural and micromechanical studies in the different regions of the fruit provided relevant information about its cellular architecture, distribution of lignocellulosic compounds and its role in the micromechanical properties of their fibers. The thickening cell wall of sclerenchyma fibers was caused by the cellular lignification of the ripe fruits. According to the physicochemical and structural studies, cuajilote fibers are comparable to other fibers obtained from crops rich in lignocellulosic compounds. The current study provided new knowledge about the cellular architecture of fruit and criteria for selecting the ripening stage adequate for the extraction of cellulose or lignin. Furthermore, information regarding the micromechanical properties of their fibers and which structural arrangement could be more convenient for mechanical reinforcement of biodegradable materials was obtained.     

Accuracy and precision of quantitative energy-dispersive x-ray spectrometry in the environmental scanning electron microscope

The accuracy and precision of quantitative energy-dispersive x-ray spectrometry in the environmental scanning electron microscope have been estimated using a series of copper / gold alloys of known composition. The mean values (five to six replicate experiments) had relative errors within +/- 5%, and most were within +/- 3.5%. All relative standard deviations were < 5% and most were < 3%. Since the standard specimens were large (approximately 500 microm) in diameter, electron scattering in the 2 torr of water vapor above the specimen did not affect the results. This level of accuracy and precision was possible only by using a novel specimen surface charge neutralization scheme.     

Microscopic analysis of “iron spot” on blue‐and‐white porcelain from Jingdezhen imperial kiln in early Ming dynasty (14th–15th century)

“Sumali,” as an imported cobalt ore from overseas, was a sort of precious and valuable pigment used for imperial kilns only, which produces characteristic “iron spot” to blue‐and‐white porcelain in early Ming Dynasty (A.D. 14th–15th century). Although there were some old studies on it, the morphology and formation of iron spot has not been fully investigated and understood. Therefore, five selected samples with typical spot from Jingdezhen imperial kiln in Ming Yongle periods (A.D. 1403–1424) were analyzed by various microscopic analysis including 3D digital microscope, SEM‐EDS and EPMA. According to SEM images, samples can be divided into three groups: un‐reflected “iron spot” without crystals, un‐reflected “iron spot” with crystals and reflected “iron spot” with crystals. Furthermore, 3D micro‐images revealed that “iron spots” separate out dendritic or snow‐shaped crystals of iron only on and parallel to the surface of glaze for which “iron spot” show strong metallic luster. Combining with microscopic observation and microanalysis on crystallization and non‐crystallization areas, it indicates that firing oxygen concentration is the ultimate causation of forming reflective iron spot which has a shallower distribution below the surface and limits crystals growing down. More details about characters of “iron spot” used “Sumali” were found and provided new clues to coloration, formation mechanism and porcelain producing technology of imperial kiln from 14th to 15th centuries of China.     

Development and comparison of the methods for quantitative electron probe X‐ray microanalysis analysis of thin specimens and their application to biological material

In recent years, there has been a return to the use of electron probe X‐ray microanalysis for biological studies but this has occurred at a time when the Hall programme which acted as the mainstay for biological microanalysis is no longer easily available. Commercial quantitative routines rely on the Cliff‐Lorimer method that was originally developed for materials science applications. Here, the development of these two main routines for obtaining quantitative data from thin specimens is outlined and the limitations that are likely to be met when the Cliff‐Lorimer routine is applied to biological specimens is discussed. The effects of specimen preparation on element content is briefly summarized and the problems encountered when using quantitative analysis on resin‐embedded materials emphasized.     

Characterization and identification of local defects in glass

The most relevant defects in glasses are categorized and investigated by appropriate microanalytical techniques. Since these defects very often present a real challenge because of complex chemical and mineralogical properties, a multimethod approach is necessary to supplement or confirm the findings from scanning techniques. The combination of electron probe microanalysis/energy-dispersive x-ray (EPMA/EDX) and laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) allows the determination of element trace concentrations in a knot, a glassy defect, thus finally enabling the identification of a special source of the defect from otherwise nondistinguishable refractories. The type of crystals can be determined exactly by the use of EPMA and x-ray dispersion (XRD), stones (a crystalline agglomerate) are analyzed by EPMA/EDX pointing to a possible source for this defect; results on metallic inclusions, "filled bubbles," and surface defects are reported and defect sources are discussed. Since close cooperation with the production departments and knowledge of production techniques and conditions are necessary for the diagnosis to take appropriate countermeasures, an approach is presented which systematically accumulates all information into a data base. The structure of such "expert systems" is described, which leads to correlation of appearance, analytical data, and source of the defects for even more accurate diagnosis and faster reaction.     

Comparison of three‐dimensional analysis and stereological techniques for quantifying lithium‐ion battery electrode microstructures

Lithium‐ion battery performance is intrinsically linked to electrode microstructure. Quantitative measurement of key structural parameters of lithium‐ion battery electrode microstructures will enable optimization as well as motivate systematic numerical studies for the improvement of battery performance. With the rapid development of 3‐D imaging techniques, quantitative assessment of 3‐D microstructures from 2‐D image sections by stereological methods appears outmoded; however, in spite of the proliferation of tomographic imaging techniques, it remains significantly easier to obtain two‐dimensional (2‐D) data sets. In this study, stereological prediction and three‐dimensional (3‐D) analysis techniques for quantitative assessment of key geometric parameters for characterizing battery electrode microstructures are examined and compared. Lithium‐ion battery electrodes were imaged using synchrotron‐based X‐ray tomographic microscopy. For each electrode sample investigated, stereological analysis was performed on reconstructed 2‐D image sections generated from tomographic imaging, whereas direct 3‐D analysis was performed on reconstructed image volumes. The analysis showed that geometric parameter estimation using 2‐D image sections is bound to be associated with ambiguity and that volume‐based 3‐D characterization of nonconvex, irregular and interconnected particles can be used to more accurately quantify spatially‐dependent parameters, such as tortuosity and pore‐phase connectivity.     

Investigation of corrosion and container integrity in metal food containers using scanning electron microscopy-X-ray microanalysis

Scanning electron microscopy and x-ray microanalysis were used to investigate microleakage, two incidences of loss of coating integrity, filiform corrosion, and sulfide black corrosion in enamel-lined metal food containers. Microleakage developed in a canned cheese sauce at the side seam weld and was traced to a hot weld and a cold weld defect. An enamel-blistering problem developed in an aseptically processed milk-based product when the tinplate was heated above its melting point; the tin melted under the enamel coating, causing the blistering. An enamel-blistering problem, due to silicon contamination of the metal surface prior to enameling, developed on the bottom of a two-piece can that contained a chicken-based product. A sulfide black problem developed in canned clams, caused by scratches in the coating that were introduced during can manufacturing. A filiform corrosion problem developed on the outside of the easy score line of enameled tinplate lids with a light tin coating 0.08 microns thick.     

3D elemental and structural analysis of biological specimens using electrons and ions

We demonstrate the utility of focused ion beam scanning electron microscopy combined with energy dispersive x-ray spectrometry for 3D morphological and elemental correlative analysis of subcellular features. Although recent advances in super-resolution light microscopy techniques and traditional transmission electron microscopy methods can provide cellular imaging at a wide range of length scales, simultaneous 3D morphological and elemental imaging of cellular features at nanometre scale can only be achieved with techniques such as focused ion beam scanning electron microscopy with energy dispersive x-ray spectrometry capability. We demonstrate the technique by analysing the 3D silicon cell wall structure of a marine diatom, Thalassiosira pseudonana. This study also highlights the limitations of the technique in its current state and suggests several possible improvements needed for the routine use of the technique for biological specimens.     

Atomic force microscopy and energy dispersive X‐ray spectrophotometry analysis of reciprocating and continuous rotary nickel‐titanium instruments following root canal retreatment

The aim was to examine the effect of retreatment process on the surface roughness and nickel titanium (NiTi) composition of ProTaper Universal Retreatment (PTUR; consists of 3 files; D1, D2, D3) and WaveOne Gold (WOG) (primary) instruments. Twenty extracted mandibular molar teeth with severe curved (30–40°) mesial roots were selected and divided into two groups (n = 10) based on the instrument used for the removal of the root canal filling. Before and after using the instruments in two canals, they were subjected to atomic force microscopy (AFM) and energy dispersive X‐ray spectrophotometry (EDX) analysis. The EDX analysis data and roughness average (Ra) and root mean square (RMS) values were analyzed statistically using a one‐way analysis of variance and post hoc Tukey's test at the 5% significant level. There was no significant difference between the new and used D1 and D2 PTUR and WOG instruments in terms of the Ni composition (p > .05). The Ti contents of the used D2 and D3 PTUR instruments were lower those of the new instruments (p < .05). In both new and used instruments, PTUR and WOG have no difference in terms of Ra and RMS values. (p > .05). The Ra and RMS values of the PTUR and WOG systems significantly increased after removal of the root canal filling (p < .05). The use of PTUR and WOG instruments for removal of root canal filling in severely curved root canals affected the surface topography of the files. The NiTi composition of the WOG instruments was unaffected by the retreatment process.     

Automated detection of fluorescent cells in in‐resin fluorescence sections for integrated light and electron microscopy

Integrated array tomography combines fluorescence and electron imaging of ultrathin sections in one microscope, and enables accurate high‐resolution correlation of fluorescent proteins to cell organelles and membranes. Large numbers of serial sections can be imaged sequentially to produce aligned volumes from both imaging modalities, thus producing enormous amounts of data that must be handled and processed using novel techniques. Here, we present a scheme for automated detection of fluorescent cells within thin resin sections, which could then be used to drive automated electron image acquisition from target regions via ‘smart tracking’. The aim of this work is to aid in optimization of the data acquisition process through automation, freeing the operator to work on other tasks and speeding up the process, while reducing data rates by only acquiring images from regions of interest. This new method is shown to be robust against noise and able to deal with regions of low fluorescence.     

核安全相关设计分析软件开发过程质量控制研究

在阐述核电工程设计分析专用软件的自主化研发工作背景的基础上,结合核电核安全相关软件开发现状,分析了软件开发过程质量控制的必要性。同时,通过对软件全生命周期过程管理以及关键管理活动的描述,详细阐述了中国核动力研究设计院在核安全相关设计分析软件开发过程质量控制方面的工作重点,即通过建立有效的软件开发过程质量管理体系、规范和流程,确保软件开发质量,提高软件的正确有效性、可靠性、可维护性和可适应性,从而为解决中国核电工程出口面临的软件自主知识产权问题,增强研究、设计工作的自主创新能力,提升核安全保障能力奠定了良好的基础。     

The analysis of dioxins and related compounds

The analysis of polychlorinated dibenzo‐p‐dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, and other related compounds requires complex sample preparation and analytical procedures using highly sensitive and selective state‐of‐the‐art instrumentation to meet very stringent data quality objectives. The analytical procedures (extraction, sample preparation), instrumentation (chromatographic separation and detection by mass spectrometry) and screening techniques for the determination of dioxins, furans, dioxin‐like polychlorinated biphenyls and related compounds with a focus on new approaches and alternate techniques to standard regulatory methods are reviewed. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:526–559, 2010