bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal conductivity and tribological properties of POM‐Cu composites
Authors: He Junqing , Zhang Ling , Li Chunzhong
Published: June 2010

The polyoxymethylene (POM) composites with different copper contents were prepared by extrusion. The thermal conductivity and tribological behavior of POM‐Cu composites with various contents of copper particles were investigated by a hot disk thermal analyzer and an M‐2000 friction and abrasion testing machine, respectively. The effect of copper particles on the thermal conductivity of POM composites was negligible when copper content was below 10 wt %. As the copper content increased, the thermal conductivity of composites increased and reached 0.477 W m−1 K−1 for POM‐25 wt % Cu composite, which increased by 35.9% compared with that of unfilled POM. The incorporation of copper particles into POM reduced the friction coefficient of POM composites. The wear mechanisms of POM‐Cu composites were adhesive and abrasive wear. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Evaluation and management of pulmonary disease in ataxia‐telangiectasia
Authors: McGrath‐Morrow Sharon A. , Gower W. Adam , Rothblum‐Oviatt Cynthia , Brody Alan S. , Langston Claire , Fan Leland L. , Lefton‐Greif Maureen A. , Crawford Thomas O. , Troche Michelle , Sandlund John T. , Auwaerter Paul G. , Easley Blaine , Loughlin Gerald M. , Carroll John L. , Lederman Howard M.
Published: June 2010

Ataxia‐telangiectasia (A‐T) is a rare autosomal recessive disorder caused by mutations in the ATM gene, resulting in faulty repair of breakages in double‐stranded DNA. The clinical phenotype is complex and is characterized by neurologic abnormalities, immunodeficiencies, susceptibility to malignancies, recurrent sinopulmonary infections, and cutaneous abnormalities. Lung disease is common in patients with A‐T and often progresses with age and neurological decline. Diseases of the respiratory system cause significant morbidity and are a frequent cause of death in the A‐T population. Lung disease in this population is thought to exhibit features of one or more of the following phenotypes: recurrent sinopulmonary infections with bronchiectasis, interstitial lung disease, and lung disease associated with neurological abnormalities. Here, we review available evidence and present expert opinion on the diagnosis, evaluation, and management of lung disease in A‐T, as discussed in a recent multidisciplinary workshop. Although more data are emerging on this unique population, many recommendations are made based on similarities to other more well‐studied diseases. Gaps in current knowledge and areas for future research in the field of pulmonary disease in A‐T are also outlined. Pediatr. Pulmonol. 2010; 45:847–859. © 2010 Wiley‐Liss, Inc.
Serum early prostate cancer antigen (EPCA) as a significant predictor of incidental prostate cancer in patients undergoing transurethral resection of the prostate for benign prostatic hyperplasia
Authors: Zhao Zhigang , Zeng Guohua , Zhong Wen
Published: June 2010

BACKGROUND

Early prostate cancer antigen (EPCA), a nuclear matrix protein, has been recently suggested as a novel biomarker in malignant lesions of the prostate. This study was to determine whether preoperative serum EPCA levels predicted the presence of incidental prostate cancer (IPCa) in patients undergoing TURP for BPH.

METHODS

Serum EPCA levels were measured by ELISA in 449 consecutive patients with symptomatic BPH treated with TURP and 112 healthy men. Predictive performance of serum EPCA levels for IPCa were evaluated.

RESULTS

With a cutoff of 10 ng/ml, serum EPCA protein had a 100% specificity for the healthy men and a 98% specificity and a 100% sensitivity in separating men with IPCa from those without. Serum EPCA levels in patients with IPCa were significantly higher than in those without and in healthy controls (17.63 ± 2.42 ng/ml vs. 5.58 ± 1.61 ng/ml and 4.95 ± 1.43 ng/ml, all P < 0.001), whereas an indwelling transurethral catheter presence and 5α‐reductase inhibitor therapy had no effect on EPCA levels (P = 0.144 and P = 0.238, respectively). The area under ROC curves (AUC) showed that serum EPCA level had the best predictive accuracy of all IPCa (AUC: 0.952, 95% CI: 0.912–0.981, P < 0.001). Univariate and multivariate Cox regression analyses further demonstrated the independently predictive performance by preoperative serum EPCA (Hazards Ratio: 4.23, 95% CI: 3.62–6.46, P < 0.001).

CONCLUSIONS

This study firstly shows that EPCA might be used as a highly sensitive and specific serum biomarker to predict IPCa presence and to help reduce the unnecessary biopsies taken before TURP in patients with BPH. Prostate 70: 1788–1798, 2010. © 2010 Wiley‐Liss, Inc.
Thrips (Thysanoptera: Thripidae) mitigation in seedling cotton using strip tillage and winter cover crops
Authors: Toews Michael D , Tubbs R Scott , Wann Dylan Q , Sullivan Dana
Published: June 2010

BACKGROUND: Thrips are the most consistent insect pests of seedling cotton in the southeastern United States, where symptoms can range from leaf curling to stand loss. In a 2 year study, thrips adults and immatures were sampled at 14, 21 and 28 days after planting on cotton planted with a thiamethoxam seed treatment in concert with crimson clover, wheat or rye winter cover crops and conventional or strip tillage to investigate potential differences in thrips infestations.

RESULTS: Densities of adult thrips, primarily Frankliniella fusca (Hinds), peaked on the first sampling date, whereas immature densities peaked on the second sampling date. Regardless of winter cover crop, plots that received strip tillage experienced significantly fewer thrips at each sampling interval. In addition, assessment of percentage ground cover 42 days after planting showed that there was more than twice as much ground cover in the strip‐tilled plots compared with conventionally tilled plots. Correlation analyses showed that increased ground cover was inversely related to thrips densities that occurred on all three sampling dates in 2008 and the final sampling date in 2009.

CONCLUSIONS: Growers who utilize strip tillage and a winter cover crop can utilize seed treatments for mitigation of early‐season thrips infestation. Copyright © 2010 Society of Chemical Industry
Improved antimicrobial activity of h‐lysozyme (107–115) by rational Ala substitution
Authors: González Rodrigo , Albericio Fernando , Cascone Osvaldo , Iannucci Nancy B.
Published: June 2010

The most challenging target in the design of new antimicrobial agents is the development of antibiotic resistance. Antimicrobial peptides are good candidates as lead compounds for the development of novel anti‐infective drugs. Here we propose the sequential substitution of each Ala residue present in a lead peptide with known antimicrobial activity by specific amino acids, rationally chosen, that could enhance the activity of the resultant peptide. Taking the fragment 107–115 of the human lysozyme as lead, two‐round screening by sequentially replacing both Ala residues (108 and 111) by distinct amino acids resulted in a novel peptide with 4‐ and 20‐fold increased antimicrobial activity against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, respectively. These results reinforce the strategy proposed, which, in combination with simple and easy screening tools, will contribute to the rapid development of new therapeutic peptides required by the market. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Wogonin inhibits osteoclast formation induced by lipopolysaccharide
Authors: Jang Sungil , Bak Eun Jung , Kim Minyoung , Kim Jin Moon , Chung Won‐Yoon , Cha Jeong‐Heon , Yoo Yun‐Jung
Published: June 2010

To evaluate the inhibitory activity of wogonin against lipopolysaccharide (LPS)‐induced bone resorption, we investigated the effect of wogonin on osteoclastogenesis induced by LPS. Wogonin inhibited LPS‐induced osteoclastogenesis in co‐cultures of mouse calvaria‐derived osteoblasts and bone marrow‐derived pre‐osteoclasts. Wogonin also suppressed osteoclastogenesis in LPS‐injected mouse calvaria. In osteoblasts, the upregulation of receptor activator of nuclear factor‐κB (RANKL) expression and the downregulation of osteoprotegerin (OPG) expression by LPS were inhibited by wogonin. Wogonin and NS‐398, a COX‐2 inhibitor, suppressed LPS‐stimulated PGE2 production in osteoblasts. NS‐398 inhibited the effect of LPS on RANKL and OPG expression in osteoblasts. These results suggest that wogonin acts as an inhibitor of LPS‐induced osteoclastogenesis through downregulation of RANKL and upregulation of OPG expression via blockage of PGE2 production. Based on these results, wogonin has potential for use as a therapeutic agent in bacteria‐induced bone resorption. Copyright © 2009 John Wiley & Sons, Ltd.
An approach to the reduction of hydrocarbon contamination in the scanning electron microscope
Authors: Postek Michael. T.
Published: June 2010

The deposition of electron beam‐induced specimen contamination in both the transmission (TEM) and scanning electron microscopes (SEM) has remained a problem since the beginning of these forms of microscopy. Generally, sources of SEM contamination can be attributed to one or a combination of three major contributors: (1) the pumping system; (2) outgassing of other internal SEM component parts (i.e., specimen stage, stage lubricants, O‐rings, etc.), or (3) the sample (including its preparation and handling). Generally, because of the nature of SEM, specimen contamination can be minimized but is difficult to avoid fully. This work outlines three approaches taken with instruments at NIST to reduce the deposition of contamination in high‐resolution cold‐field emission SEMs. With some modification these techniques could be applied to any SEM. These approaches have been in successful operation for several years, resulting in a reduction in electron beam‐induced hydrocarbon contamination.
Electron‐gas interactions in the environmental scanning electron microscopes gaseous detector
Authors: Meredith P. , Donald A. M. , Thiel B.
Published: June 2010

The construction of high signal‐to‐noise, artefact‐free secondary electron images in the elevated pressure conditions of an environmental SEM is a nontrivial process. The interactions of information carrying species, as well as probe beam electrons, with the chamber gas are the major reasons for such complications. In this paper, we discuss and review the present understanding of these phenomena. In addition, we outline procedures for assessing the signal‐amplifying and charge‐neutralising capabilities of an environmental gas. It is only with a knowledge of such parameters and an appreciation of the gas‐electron collision processes that one can optimise the microscope's operating parameters. Moreover, such information enables the separation of topographic detail from artefactual features in the detected electron images.
Fibre rising and surface roughening in lightweight coated paper—An environmental scanning electron microscopy study
Authors: de Roever Emon D. W. F. , Cosper David R.
Published: June 2010

Printing with water‐based ink may suffer from fibre rising and associated surface roughening due to the wetting involved. These detrimental changes were simulated in commercial lightweight coated (LWC) paper by wetting and drying in the environmental scanning electron microscope (ESEM) sample chamber. Most fibres in the basesheets [made from thermomechanical pulp (TMP) and groundwood] were flat and ribbon‐like. They swelled upon wetting and shrank upon drying, but remained flat. These changes were reversible. Other fibres were hollow and tube‐like. They also expanded upon wetting, but showed different behaviour upon drying: (1) flattening and collapse; or (2) retention of the tube shape and, in some cases, movement of loose fibre ends. Some fibre ends rose out of the sheet surface upon drying. Rewetting returned the fibre ends to a position largely within the sheet surface. Further drying resulted in rising again. Isolated groundwood and TMP fibres with tube shape showed the same types of contrasting behaviour, that is, collapse upon drying or retention of the tube shape. From these observations we conclude that fibre rising is limited to comparatively stiff fibres that maintain their shape upon wetting and drying. Rising occurred during drying, not during wetting and swelling. Fibre rising might be avoided by eliminating the tube‐like fibres, or by further refining to reduce their stiffness to an acceptable level. As evidence of this, we observed that some of the TMP fibres collapsed upon drying instead of showing rising. Fibre rising was thus observed here in fibres which retain their tube‐like shape (despite refining and calendering) and not, as suggested in the literature, in ribbon‐like fibres returning to an uncollapsed tube‐like shape when wetted. Fibre rising was less common in the sheets than expected from the strong gloss reduction and surface roughening of the LWC paper seen upon wetting (outside the ESEM). In other words, gloss reduction and roughening may be caused in part by processes other than fibre rising. Roughening might also result from the association of flat and tube‐like fibres in the sheet. Tube‐like fibres swell radially (vertically) much more than do flat, collapsed fibres, which leads to thin zones in the coating over the raised fibres and coating cracks along their edges. These types of damage of the coating were quite common. This mode of sheet roughening does not require fibre rising in the strict sense, that is, rising of fibre ends out of the sheet surface, but the tube‐like fibres causing it might show fibre rising at their tails to some extent.
Environmental microscopy in stone conservation
Authors: Rao Sudeep M. , Brinker C. Jeffrey , Ross Timothy. J.
Published: June 2010

The natural weathering of stone is accelerated by the combined effects of acid rain, salt crystallization, and the freeze‐thaw cycles of water. Since weathering will take place until the system reaches chemical equilibrium, we can mitigate the loss to historic stone monuments and structures by treatments of the stone that retard hydrolysis and impart mechanical strength. While macroscopic studies of stone weathering have been performed addressing the causes, the reactions, and the kinetics involved, the mechanisms of weathering, and the chemical remediation of stone need to be better understood at a microscopic level. Our approach uses environmental scanning electron microscopy where samples can be imaged in their wet, natural state, thus facilitating the in situ study of the weathering processes. The environment in the microscope is set up to simulate the conditions of degradation by introducing corrosive liquids and gases and varying the temperature, pressure, and water content in the environmental chamber of the microscope. In this study, we observed specimens of limestone, treated calcite, and sandstone. We have characterized the morphology, structure, and chemical constituents of the samples for comparison at a later stage when protective coatings will be applied. In situ leaching tests were performed on limestone samples to study the mechanisms of degradation. Granular disintegration due to leaching of the binding material between the grains was seen. We have also observed, in situ, the changes in the structure of sodium sulfate, used in salt crystallization tests, during hydration and dehydration cycles; it changed from that of dense grains to hydrated mesoporous granules with the generation of new surface area.
Image sharpness measurement in scanning electron microscopy—part II
Authors: Vladár Andrá E. , Postek Michael T. , Davidson Mark. P.
Published: June 2010

A method for qualitative and quantitative analysis of scanning electron microscope (SEM) images forthe determination of sharpness is presented in this paper. Described is a procedure for qualitative analysis based on a software program called SEM Monitor that can be applied to research or industrial SEMs for day‐to‐day performance monitoring. The idea is based on the fact that, as the electron beam scans the sample, the low‐frequency changes in the video signal show information about the larger features and the high‐frequency changes give data on finer details. The image contains information about the primary electron beam and about all the parts contributing to the signal formation in the SEM. If everything else is kept unchanged, with a suitable sample, the geometric parameters of the primary electron beam can be mathematically determined. An image of a sample, which has fine details at a given magnification, is sharper if there are more high frequency changes in it. In the SEM, a better focused electron beam yields a sharper image, and this sharpness can be measured. The method described is based on calculations in the frequency domain and can also be used to check and optimize two basic parameters of the primary electron beam, the focus, and the astigmatism.
The use of helium gas to reduce beam scattering in high vapour pressure scanning electron microscopy applications
Authors: Stowe S. J. , Robinson V. N. E.
Published: June 2010

Both image quality and the accuracy of x‐ray analysis invariable pressure scanning electron microscopes (VPSEMs) are often limited by the spread of the primary electronbeam due to scattering by the introduced gas. The degree of electron scattering depends partly on the atomic number Z of the gas, and the use of a low Z gas such as helium should reduce beam scattering and enhance image quality. Using anuncoated test sample of copper iron sulphide inclusions in calcium fluorite, we show that the reduction in beam scatter produced by helium is more than sufficient to compensate for its reduced efficiency of charge neutralisation. The relative insensitivity to pressure of x‐ray measurements in a helium atmosphere compared with air, and the consequent ability to work over a wider range of working distances, pressures, and voltages, make helium potentially the gas of choice for many routine VPSEM applications.
Assessment of stress fiber orientation during healing of radial keratotomy wounds using confocal microscopy
Authors: Petroll W. Matthew , Cavanagh H. Dwight , Jester James V.
Published: June 2010

Radial keratotomy (RK) is a refractive surgical procedure in which partial thickness incisions are made in the cornea in order to alter its shape. Previous studies suggest that RK wounds undergo changes in wound gape in response to the in growth of myofibroblasts which mediate subsequent wound contraction and may modulate changes in corneal curvature seen after RK. A recent quantitative analysis of f‐actin organization in full‐thickness incisional wounds in the rabbit demonstrated that microfilament bundles (stress fibers) present in myofibroblasts alignparallel to the long axis of the wound during wound contraction. To investigate whether the same pattern of alignment occurs after RK, a similar analysis of f‐actin organization was undertaken using the cat RK model. Radial keratotomy wounds were studied from 10 to 28 days after surgery using en block staining with fluorescein isothiocyanate (FITC) phalloidin, and three‐dimensional (3‐D) datasets (z‐series of en face optical sections) were collected using laser confocal microscopy at various regions within the wound. In addition, conventional en face sections were double‐labeled using combinations of phalloidin and antibodies to fibronectin and α5β1 integrin. Myofibroblast ingrowth started in the bottom of the wound and progressed anteriorly. At 10 to 14 days, f‐actin was predominantly distributed in long, thick bundles (stress fibers) within the wound. These fibers appeared to be randomly oriented anteriorly, but became progressively more aligned with the long axis of the wound posteriorly. At 21 days, the stress fibers were predominantly oriented parallel to the long axis of the wound at all levels. F‐actin, fibronectin and integrin were coalignedatboththe 14 and 21 day time points. Since the majority of wound closure occurs between 14 and 28 days after surgery, we conclude that parallel alignment of the actin filament‐fibronectin‐integrin assembly in the cat RK model is associated with wound contraction.
The detection of low‐intensity peaks in energy dispersive x‐ray spectra from particles
Authors: Small John. A.
Published: June 2010

A critical step in the processing of energy dispersive (EDS) x‐ray spectra from the automated scanning electron microscopy (ASEM) analysis of particles is the detection and identification of elemental peaks. Since there are often several hundred to several thousand spectra for each ASEM analysis, it is important that this step operate rapidly and with a minimum of interaction between analyst and the program. For peaks with large peak‐to‐background (P/B) ratios, most peak‐find or peak‐fitting methods do a reasonable job even when the spectra have low signal‐to‐noise (S/N) ratios. The detection of peaks with small P/B ratios is much more problematical. Peak identification and fitting procedures may not work well on low‐intensity peaks, particularly in spectra with low S/N ratios. In this study, three procedures for identifying x‐ray peaks, with small P/B ratios in spectra with varying S/N ratios, were evaluated. The first procedure was the identification of peaks by human analysts. The results from the analysts were then used to set a benchmark for the performance of two computer‐based procedures that included three different qualitative peak identification methods, and one quantitative analysis procedure. The success of the qualitative methods in finding small peaks varied widely. In general, the quantitative analysis procedure performed as well as the best human analysts and was better than the qualitative methods.
Using fractal dimensions to characterize atomic force microscope images of epoxy resin fracture surfaces
Authors: Joseph Tom , Chen Zheng , Mecholsky J. J. , Beatty Charles
Published: June 2010

Atomic force microscopy was used to obtain images of the fracture surface of a tri‐ethylene‐tetramine and 4,4 (methyl thylidene) epoxy resin. Images were obtained in the mirror, mist, and hackle regions of each sample. Fractal dimensions were calculated from the images using the box dimension and contour analysis method. The box dimension fractal dimension increment for all regions on the fracture surfaces were determined to average 0.26 ± 0.06 and the contour analysis fractal dimension increment were determined to average 0.46 ± 0.05. The box dimension technique is shown to provide the “true” fractal dimension of the surface. The fractal dimension measurements for all three regions indicated that the fracture surface was self‐affine and possibly self‐similar.
Measurement of crystal parameters on backscatter kikuchi diffraction patterns
Authors: Baba‐Kishi K. Z.
Published: June 2010

Electron backscatter Kikuchi diffraction patterns (BKDPs) recorded in the scanning electron microscope (SEM) require measurements on the plane of the photographic film or on the recording screen. The parameters that require measurements are the equivalent electron source point on the pattern, or pattern centre, specimen‐to‐film distance, true interzonal angles, true interplanar angles, Bragg angles, and interplanar spacing. In this paper, the geometry and the methods of calculation of these parameters on BKDPs recorded directly on film are described in detail. The methods described are suitable for practical purposes, providing speed of calculation but limited accuracy. The inherent factors that limit the accuracy of any measurements on BKDPs are the limitations of the gnomonic projection, resulting in projected distortions in Kikuchi bands and diffuseness of Kikuchi band edges originating from inelastic scattering of electrons. The methods described are applied to crystallographic analysis of BKDPs recorded from silicon and polycrystalline copper.
Image comparisons of snow and ice crystals photographed by light (video) microscopy and low‐temperature scanning electron microscopy
Authors: Wergin William P. , Erbe Eric F. , Rango Albert
Published: June 2010

Light (video) microscopy and low‐temperature scanning electron microscopy (SEM) were used to examine and record images of identical precipitated and metamorphosed snow crystals as well as glacial ice grains. Collection procedures enabled numerous samples from distant locations to be shipped to a laboratory for storage and/or observation. The frozen samples could be imaged with a video microscope in the laboratory at ambient temperatures or with the low‐temperature SEM. Stereo images obtained by video microscopy or low‐temperature SEM greatly increased the ease of structural interpretations. The preparation procedures that were used for low‐temperature SEM did not result in sublimation or melting. However, this technique did provide far greater resolution and depth of focus over that of the video microscope. The advantage of resolution was especially evident when examining the small particles associated with rime and graupel (snow crystals encumbered with frozen water droplets), whereas the greater depth of focus provided clearer photographs of large crystals such as depth hoar, and ice. Because the SEM images contained only surface information while the video images were frequently confounded by surface and internal information, the SEM images also clarified the structural features of depth hoar crystals and ice grains. Low‐temperature SEM appears to have considerable promise for future investigations of snow and ice.
A robust focusing and astigmatism correction method for the scanning electron microscope—Part II: Autocorrelation‐based coarse focusing method
Authors: Ong K. H. , Phang J. C. H. , Thong J. T. L.
Published: June 2010

This paper describes the development of a new coarse focusing algorithm for the scanning electron microscope (SEM). The algorithm is based on a new focus parameter that has been developed for quantifying the sharpness of an image. This parameter is found to be more robust to noise compared with other conventional focus parameters. A peak detection technique is also incorporated to shorten the number of iterations needed for the coarse focusing. Results show that the coarse focusing algorithm is able to bring a defocused and astigmatic image to either the best focus, the upper line focus, or the lower line focus in fewer iterations compared with the conventional approach in which the full focus range is searched.
A robust focusing and astigmatism correction method for the scanning electron microscope—Part III: An improved technique
Authors: Ong K. H. , Phang J. C. H. , Thong J. T. L.
Published: June 2010

As described in a previous work, a new technique has been developed to perform automatic focusing and astigmatism correction on any general scanning electron microscope (SEM) sample ranging from gold‐on‐carbon to integrated circuit (IC) tracks. In this work, various improvements made to this technique are reported. They include the implementation of direct control of the SEM and the development of three new algorithms, namely the adaptive fast Fourier transform (FFT) algorithm, the coarse focusing algorithm, and the fine focusing algorithm. Direct control reduces the communication time with the SEM while the three new algorithms are integrated with the existing technique to make it even more robust to noise and to extend it to correct images with any degree of defocus and astigmatism. The enhanced focusing and astigmatism correction algorithm is able to perform the correction in a shorter time while maintaining the accuracy of the original algorithm even under noisy conditions.
Peculiarities of diamonds formed in alkaline carbonate‐carbon melts at pressures of 8–10 GPA: Scanning electron microscopy and cathodoluminescence data
Authors: Litvin Y. A. , Chudinovskikh L. T. , Saparin G. V. , Obyden S. K. , Chukichev M. V. , Vavilov V. S.
Published: June 2010

Diamond crystallization with both spontaneous and seeded nucleation was realized in the system Na2Mg(CO3)2‐K2Mg(CO3)2‐C (graphite) at 8–10 GPa and 1700–1800°C. The crystallization products were transparent colorless diamond single crystals of octahedral habit up to 100–150 μm in size. Scanning electron microscopy (SEM) showed that the growing diamond material was precipitated on both octahedral {111} and cubic { 100 } faces of synthetic and natural diamond seed crystals by layers of octahedral orientation, much like the growth of the natural diamond. The physicochemical conditions for diamond crystallization are interpreted as a crystal growth from carbon solutions in alkaline‐carbonate melts. Color cathodoluminescence scanning electron microscopy (CCL‐SEM) and cathodoluminescence (CL) spectroscopy studies suggested specific peculiarities of the synthetic “carbonate‐carbon”(CC) diamonds resembling natural crystals in comparison with diamonds produced by metal‐carbon (MC) synthesis. The main feature of the CC product is the lack, for both spontaneous and seed stimulated diamonds, of surface color cathodoluminescence as in the case for natural diamonds with lower concentrations of nitrogen impurity (type II). The CL spectra of the CC diamonds showed the simultaneous luminescent three‐band system ‐ H3, 575 nm, and a weak blue A‐band ‐ the H3 band structure of which resembles that of natural diamonds of type IIa.
Structural characteristics of stored black beans (Phaseolus vulgaris L.)
Authors: De J. Berrios Jose , Swanson Barry G. , Cheong W. Adeline
Published: June 2010

Scanning electron microscopy (SEM) was used to study and compare the structural characteristics of black beans after 2 years of storage under ambient conditions (AC) and refrigerated hypobaric conditions (RHC). The exterior surface of the seed coats of the black beans were covered with small flake‐like materials randomly clustered together. The hilar regions of black beans stored under either AC or RHC were similar, and the “linea lucida” exhibited well defined double palisade cell layers in both bean treatments. Cross sections of the seed coats revealed that the parenchymal cell layers of the beans stored under AC were disrupted and frequently exhibited large intercellular spaces between the cell layers. The parenchymal cell layers of the beans stored under RHC demonstrated little disruption of the cell layers, with only occasional intercellular spaces between the cell layers. Cotyledon cross sections of blackbeans showed that the cotyledon cells of the beans stored under RHC exhibited many large intercellular spaces characteristic of normal beans. Conversely, cotyledon cross sections of the beans stored under AC exhibited cotyledon cells with few small intercellular spaces characteristic of hard‐to‐cook beans.
Mc3D: A three‐dimensional Monte Carlo system simulating image contrast in surface analytical scanning electron microscopy I—Object‐oriented software design and tests
Authors: Yan H. , Gomati M. M. El , Chu D. P. , Dowsett M. G. , Prutton M. , Wilkinson D. K.
Published: June 2010

The main features of a three‐dimensional (3‐D) Monte Carlo software system (Mc3D), designed for the simulation of electron scattering and image contrast in a scanning electron microscope, are reported. Before simulating electron trajectories in the sample, impingement of the incident electron beam is described by introducing the idea of a virtual scan path in 3‐D space. A general and concise algorithm is given for simulating the intersection of electron trajectories leaving the sample onto multidetector entrance apertures distributed in 3‐D space. By optimising the object‐oriented design in conjunction with the use of a process‐oriented and data‐oriented code structure, Mc3D is capable of simulating microscopic analysis of a sample with a 3‐D geometry or structure that can be expressed with formulae. Three examples of the use of Mc3D are given. The first is for linescans across a block of SiO2 on top of a Si substrate; the second is for a stripe of SiO2 embedded in a Si substrate. Finally, the simulation of Auger linescans across an Au overlay on Si is compared with experimental results. The relationships between experimental linescans and the true beam impact positions on the sample are revealed through the virtual scan path. An edge effect, parallel‐edge enhancement, is predicted when the incident electron beam size, the distance of impact position to the terrace edge, and the inelastic mean free path of the Auger electron from a given element are comparable, and the linescan is parallel to the terrace edge. All three examples demonstrate the sensitivity of image contrast to the disposition of the sample with respect to the electron column and the detector position.
Performance of a tilt‐compensating tube scanner in atomic force microscopy
Authors: Hannss M. , Naumann W. , Anton R.
Published: June 2010

A tube scanner is constructed which avoids tilting of the sample surface when areas at some distance off the tube axis are scanned. Such tilt occurs with conventional piezo tubes, causes distorted vertical scaling, and limits the field of view to a few μm. These problems are partly overcome with a new design, which also uses a single tube, but with eight‐segmented electrodes. It can be thought of being constructed of two four‐segmented, conventional tubes, with the x‐ and y‐sections in the two parts being connected crosswise. While no additional voltage supply is needed, the tube is forming an s‐like shape, such that the bending of one half of the tube is compensated by a similar bending, but in the opposite direction, of the other half. Moreover, the displacement of the sample surface in z‐direction can be compensated quantitatively by suitable compression or dilatation of the tube, which can always be calculated from the known lateral displacement of the axis. The performance of this scanner is demonstrated on steps of a calibration replica.
Photon scanning tunneling microscope, now and in the future
Authors: Wu Shifa
Published: June 2010

The concept of photon tunneling and the principle of the photon scanning tunneling microscope (PSTM) are described. The history of the PSTM and its development in China are reviewed. The principal problem in the recent development of the PSTM, together with its solution, is discussed. The distinguishing features and the future of the PSTM are described.
The fourier optics of near‐field microscopy
Authors: Sheppard C. J. R. , Fatemi H. , Gu Min
Published: June 2010

Many different optical schemes for achieving super‐resolution by probing a near field have been proposed and one of the most important of these is the use of a tapered optical fibre probe. Plain optical fibre probes have also been used for microscopy. The Fourier optics behind these various methods are considered, contrast mechanisms discussed, and the concept of the transfer function for an evanescent field developed.
Observations of snow crystals using low‐temperature scanning electron microscopy
Authors: Wergin William P. , Rango Albert , Erbe Eric F.
Published: June 2010

Low‐temperature scanning electron microscopy (SEM) was used to observe precipitation particles commonly known as “snowflakes.” The snowflakes were collected in Beltsville, Maryland, at temperatures ranging from −6° to +1°C, mounted on SEM stubs, frozen in liquid nitrogen (LN2), and then transferred to a cryosystem mounted on a field‐emission SEM. Neither sputter coating with platinum nor irradiation by the electron beam affected their delicate fine structure. SEM observations revealed that snowflakes consisted of aggregations of snow crystals that occurred as hexagonal plates, prismatic columns, needles, and dendrites. In some cases, the snow crystals contained minute surface structures that consisted of rime, microdroplets, short prismatic columns, and amorphous films. Snow crystals from wet snow, which were collected at temperatures of 0° and +1°C, exhibited varying degrees of metamorphism or melting. The discrete crystalline faces and their sharp intersecting angles were gradually replaced by sinuous surfaces that tended to exhibit more spherical shapes. This study indicates that low‐temperature SEM is a valuable technique for studying the formation and metamorphosis of snow crystals. The results suggest that combining low‐temperature SEM and x‐ray analysis could also provide qualitative elemental information on the nucleation particles of snow crystals as well as on the composition of acid snow.
Metallurgical interactions at the contacts GaAs interface
Authors: Cole M. W. , Han W. Y. , Casas L. M. , Eckart D. W. , Jones K. A.
Published: June 2010

Interface morphology, phase composition, and elemental diffusion of Pt/Ti/Ge/Pd ohmic contacts to both n and p+‐GaAs have been investigated as a function of annealing temperature. Structural and chemical results were correlated with specific contact resistances (ρc) measured for each thermal treatment. Annealing at 450°C yielded the lowest ρc, ∼6.4 × 10−7Ω‐cm2. The interface was observed to be smooth and abrupt. Two interface phases were detected; a primary phase, PdGe, and a secondary, Ga‐rich Pd‐Ga‐As ternary phase. The presence of this ternary phase was found to be critical to contact formation on n‐GaAs. The Ti and Pt layers remained pristine. Annealing at 550°C resulted in a slightly higher ρc, ∼2.1 × 10−6Ω‐cm2. There was significant elemental diffusion within the contact metal and minor diffusion into the GaAs substrate. The interface possessed limited areas of spiking with uniform composition. Annealing at 600°C proved to have a detrimental effect on the ρc, ∼10−4Ω‐cm2. This electrical degradation was accompanied by strong chemical intermixing between the contact and substrate, resulting in a continuous nonplanar interface with deep multiphase protrusions.
A semiautomated image analysis procedure for the quantification of dental microwear II
Authors: Ungar Peter S.
Published: June 2010

Paleontologists often examine microscopic scratches and pits that form on teeth for indications of the diets of past animals. Most researchers count and measure scratches and pits from photomicrographs to identify microwear patterns for comparison among samples. This paper describes an affordable, available semiautomated image analysis procedure for microwear quantification. An image is downloaded from a scanning electron microscope frame buffer to a microcomputer, and the user identifies microwear features with a mouse‐driven pointer. Microwear feature density, dimensions, and orientations are then computed and stored as ASCII files for subsequent data analysis.
A database on electron‐solid interactions
Authors: Joy David C.
Published: June 2010

Monte Carlo modeling of electron‐solid interactions requires a detailed and accurate supply of experimental data on which to base its physics and against which to test its predictions. To meet this need, a collection of data—comprising measurements of secondary and backscattered electron yields, electron stopping powers, and x‐ray ionization cross sections, as a function of energy—has been assembled from published sources. The quality and quantity of the compilation varies widely, with little or no data being available for the majority of elements in the periodic table, while results for complex materials of current technologic interest are also almost nonexistent. To meet the needs of Monte Carlo simulation in areas such as dimensional metrology or microanalysis, a program of systematic measurements is required.
Is your scanning electron microscope Hi‐Fi?
Authors: Vladár András E. , Postek Michael T. , Davilla Scott D.
Published: June 2010

The scanning electron microscope (SEM) historically has been used mainly as an image‐producing device and, in spite of certain obvious and sometimes serious electronics problems, serves in this function as an acceptable and effective instrument for many applications. Today, the SEM is being used in areas other than imaging. The major area of current use and of concern of this Workshop paper is SEM‐based metrology. SEM‐based metrology is of great interest to the microelectronics industry, and for this industry, measurement accuracy and repeatability issues have become paramount. This paper presents a short description of some of the electrical properties of different components of an SEM which can seriously affect its performance as a metrology tool. These include the electronics associated with the formation of the electron beam and scanning circuitry, the electron detectors, the video signal chain, and the analog‐to‐digital (AD) and digital‐to‐analog (DA) conversion circuits. This discussion relates the possible influences generated by these components to the detected and observed signal. This paper also includes the concept that computer modeling of the SEM image, with Monte Carlo or other techniques, must be done completely in order to be meaningful. Modeling just the electron beam/sample interactions alone only deals with a portion of the issues. Any modeling must include the shortcomings of the real, nonideal measuring tool. By knowing the electrical characteristics and possible imperfections caused by the different parts of an SEM, a more accurate comparison of the measured and calculated signal can be made. One practical example is presented which demonstrates how it is possible to improve the agreement between calculated and measured signals.
Atomic and magnetic force microscopy imaging of thin‐film recording heads
Authors: Chim W. K.
Published: June 2010

Investigations on the use of the scanning probe microscope (SPM) in the atomic force microscopy (AFM) mode for topography imaging and the magnetic force microscopy (MFM) mode for magnetic imaging are presented for a thin‐film recording head. Results showed that the SPM is suitable for imaging the surface profile of the recording head, determining the width of the pole gap region, and mapping the magnetic field patterns of the recording head excited under current bias conditions of different polarity. For the cobalt sputter‐coated tips used in MFM imaging, it was found that the magnetic field patterns obtained under different polarities of the current bias to the recording head were similar. This can be explained by the nature of the thin‐film MFM tip, in which the direction of the tip magnetic moment can follow the stray magnetic field of the sample as the current bias to the recording head reverses in direction.
Charging control using pulsed scanning electron microscopy
Authors: Wong W. K. , Phang J. C. H. , Thong J. T. L.
Published: June 2010

This paper describes a novel method to observe highly charging specimens at high‐beam voltages without specimen preparation. It is found that the technique greatly reduces charging artifacts such as image shift, astigmatism, and defocussing without sacrificing image quality. Images obtained of uncoated specimens are found to be comparable to gold‐coated specimens and without exhibiting charging effects. The technique also allows the study of charge distribution effects in specimen charging of which very little understanding exists, particularly as far as the spatial and time‐dependent properties of charging are concerned.
Simple modifications for accurate high‐temperature gas exposures using scanning electron microscopy
Authors: Poston James A.
Published: June 2010

Relatively low‐cost modifications to standard commercial scanning electron microscopes (SEM) that allow accurate exposure of sample(s) to noncorrosive gases at ambient and high temperatures are outlined. Energy‐dispersive spectroscopic analysis of sample(s) exposed to noncorrosive gases at high temperatures is demonstrated. Gas exposure is limited to pressures of less than 10−4 torr (1.33 × 10−2 Pa) as a result of limitations on SEM system operation and SEM safety interlocks. Gases are limited to noncorrosive types as a result of potential damage to system detection devices and internal mechanical parts.
Morphologic and cathodoluminescence studies of diamond films by scanning electron microscopy
Authors: Saparin G. V. , Obyden S. K.
Published: June 2010

Using recent papers on scanning electron microscopy (SEM) of chemical vapor deposition (CVD) diamond films, two analytical applications of the SEM are discussed: the morphologic investigations (secondary electron emission mode) and the recognition of impurities and defects [cathodoluminescence (CL) mode]. Studies of CVD diamond films by SEM demonstrate that the morphologies of these films are affected by synthesis conditions, especially by substrate temperature, methane concentration, and total pressure in the reactor. CL spectra and images are useful tools for clarifying the relationship between emission centers and different types of defects generated during the process of diamond crystal growth. The paper shows that the investigations of the morphology, crystallinity, local CL emission, as well as the surface distribution of CL spectra on CVD diamond films by SEM led to the correlative information for quality estimation of films in comparison with natural diamond.
Characterization of electron scattering in solids using a generalized walk
Authors: Gauvin Raynald
Published: June 2010

A new method to characterize electron scattering in solids is presented. This method is based on the concept of fractal geometry leading to a generalized walk. A criterion is presented to validate the applicability of this method. This method is applied to random walks with variable mean free path to validate it. Finally, this method is applied to the diffusion of incident electrons in solids of gold and carbon to characterize the transition between persistent and random walk processes describing the diffusion of the electrons in these materials.
Analysis of sections of implanted macroporous calcium phosphate bone substitutes by proton‐induced x‐emission method and energy‐dispersive spectrometry
Authors: Frayssinet P. , Braye F. , Weber G.
Published: June 2010

The osseointegration of porous calcium phosphate ceramics once implanted evolves in several stages. The mechanism of integration of such material usually is evaluated by histologic analysis. The trace elements present in bone can be detected in the ceramic and help to provide a semiquanti‐tative evaluation of osseointegration. Two different methods of microanalysis, energy‐dispersive spectrometry (EDS) and proton induced x‐emission (PIXE) were used in this study to determine the appearance of trace elements (Zn, Sr, and Fe) present in bone at the implantation site containing the ceramic. Porous HA‐ceramic cylinders were implanted in the cortical bone of sheep femurs for periods ranging from 2 to 36 weeks. Thick sections of the implant‐containing bone were made at the end of the implantation period. A scanning line with proton or electron impacts 0.5 mm apart was plotted from the edges of the cortical bone across the implanted ceramic and the resulting x‐ray spectra were determined. Following EDS analysis, the sections were surface‐stained, observed under a light microscope, and the pore volume occupied by bone tissue was measured. The spectra obtained by PIXE method showed two regions for each element characterising either the bone tissue or the ceramic. Zinc and strontium present in the bone tissue, but absent from the ceramic, appeared 8 and 12 weeks after implantation, respectively. The concentration of iron present in the implant decreased with time. EDS showed no significant level of either element in the bone or the ceramic. Histologic observation revealed that immature bone invaded the pores of the outer layer of the ceramic as early as 2 weeks after implantation. The ceramics were totally osseoin‐tegrated 20 weeks after implantation, although ceramic degradation continued for longer. In this experiment, the PIXE method was apparently sufficiently sensitive for monitoring the amount of trace element appearing in bone‐implanted material.