Contrast mechanism at landing energy near 0 eV in super low energy scanning electron microscopy.

In recent years, the technique of scanning electron microscopy (SEM) observation with low landing energy of a few keV or less has become common. We have especially focused on the drastic contrast change at near 0 eV. Using a patterned sample consisting of Si, Ni and Pt, threshold energies where total reflection of incident electrons occur was investigated by SEM at near 0 eV. In both the cases of in-situ and ex-situ sample cleaning, drastic changes in the brightness of each material were observed at near 0 eV, with threshold energies in the order Si < Ni < Pt. This order agreed with the order of the literature values of the work functions and the surface potentials measured by Kelvin force probe microscopy. This result suggests that the difference of the threshold energy is caused by the difference in surface potential due to the work function difference of each material. Although the order of the threshold energies also agreed with those of work functions reported in literatures, the work functions of air exposed surfaces should be rather considered as "modified work functions", since they could be significantly altered by the adsorbates etc. Nevertheless, the difference of threshold energy for each material was observed with commercial SEM at landing energy near 0 eV, which opens new possibility to distinguish materials, although the difference should be rather recognized as "fingerprints", since surface potentials are sensitive to conditions of surface treatments and atmospheric exposure. Mini-abstract In this study, we utilized a commercial SEM with near 0 eV landing energy to explore threshold energies where total reflection occurs for various materials in air-exposed model samples. Our results demonstrate the potential of threshold energy as a distinctive fingerprint for material differentiation.

Effect of native oxide on the crystal orientation contrast in SEM micrographs obtained at hundreds, tens and units of eV.

This paper aims to elucidate the effect of native air-formed oxide on the crystallographic contrast between differently oriented copper grains in scanning electron microscope images obtained at energies from 0 eV up to 1 keV. The contrast between the Cu grains is strongly affected by the presence of native oxide. The crystallographic orientation contrast between the grains without covering the native oxide layer is relatively weak at hundreds of eV, negligible at tens of eV, and dramatically increases at energies below 10 eV. At extremely low landing energies, say below ~ 1 eV, the surface potential differences caused by work function variations between the differently oriented Cu grains affect the primary electrons, which enables us to obtain the micrographs with high crystallographic contrast. This contrast becomes surprisingly visible even if the grains are covered by a several nm thick native oxide layer. The presence of the native air-formed oxide layer on the Cu surface is inconsiderable for the contrast formation at energies close to the mirror conditions (< 1 eV). The surface potential differences originating in the substrate can affect the incident electrons through the native oxide film situated on the Cu surface. Scanning low-energy electron microscopy is a powerful tool for mapping local work function differences with a spatial resolution slightly better than 30 nm due to high sensitivity to local electrical potentials.

Cation Specific Effects on the Domain-Domain Interaction of Heterogeneous Dimeric Protein Revealed by FRET Analysis.

Specific monovalent cation effects on the domain-domain interaction of heterogeneous dimeric protein were investigated using green fluorescent protein (GFP)-glutathione-s-transferase (GST) fusion protein as a model protein. Conjugating N-terminal of GST domain with a fluorescence probe Cyanine3, complementary increase and decrease of fluorescence intensities of Cyanine3 and GFP were recognized on the exclusive excitation of GFP and further the fluorescence decay of GFP was remarkably accelerated to show that an excellent Förster type of resonance excitation energy transfer (FRET) pair was constructed between GFP- and GST-domain. The spectral overlap integral and critical distance of the FRET pair were estimated to be 5.96×1013 M-1cm3 and 62.5 Å, respectively. The FRET rate and efficiency evaluated by fluorescence lifetime of the energy donor, GFP, were influenced by the monovalent cations included in the buffer solution to suggest that the domain-domain interactions of GFP-GST fusion protein would be susceptible to cation species and their concentrations. The order affecting the domain-domain interaction was estimated to be Li+>NH4+ >Na+>K+>Cs+, almost corresponding to the reverse Hofmeister series.

Laparoscopically Assisted Anorectoplasty for Intermediate-Type Imperforate Anus: Comparison of Surgical Outcomes with the Sacroperineal Approach.

Aim: This study aimed to compare the surgical outcomes of patients with the intermediate-type imperforate anus who underwent laparoscopically assisted anorectoplasty (LAARP; L group) with those of patients who underwent sacroperineal anorectoplasty (S group). Materials and Methods: The medical records of patients with intermediate-type imperforate anus at a single institution between April 1983 and April 2017 were retrospectively reviewed. Fecal continence was evaluated using the clinical assessment score for fecal continence developed by the Japanese Study Group of Anorectal Anomalies (maximum score, 8). Results: Twelve cases (rectobulbar urethral fistula, 7; anal agenesis without fistula, 4; and rectovaginal fistula, 1) were included in the L group versus 14 cases (rectobulbar urethral fistula, 11, and anal agenesis without fistula, 3) in the S group. Age and body weight at the time of surgery and rate of associated anomalies did not differ significantly between the two groups. The total scores for fecal continence 3, 5, and 7 years after anorectoplasty were 4, 5, and 4 points in the L group and 4, 5, and 6 points in the S group, respectively, showing no significant intergroup differences. Mucosal prolapse occurred in 50% of the L group and 29% of the S group (P = .42), but failed rectocutaneous anastomosis and anal stenosis were not identified in either group. Conclusions: Postoperative fecal continence and the incidence of complications after LAARP were comparable with those after sacroperineal anorectoplasty in patients with intermediate-type imperforate anus.

Comparison of Three- and Two-Dimensional Laparoscopy in Pediatric Nissen Fundoplication.

Aim: This study aimed to evaluate the usefulness of three-dimensional (3D) versus conventional two-dimensional (2D) vision in pediatric laparoscopic Nissen fundoplication. Materials and Methods: Medical records and procedure videos of patients 18 years old or younger who underwent laparoscopic Nissen fundoplication at a single institution between January 2015 and August 2018 were retrospectively reviewed. The total pneumoperitoneum and wrapping times were measured. The number of errors during the first stitch of the wrapping was counted. Three-dimensional laparoscopy was introduced in January 2017, and data were compared between the previous 2D and current 3D groups. A questionnaire was provided to each surgeon who performed the 3D procedure. Results: Laparoscopic fundoplication was performed under 2D vision in 32 patients and under 3D vision in 19 patients. Mean ages and weights at surgery were similar between the groups. There was no significant differences in pneumoperitoneum and wrapping times between the two groups. Significantly more errors were counted in the 2D versus 3D procedure, but all patients recovered without any complications related to intraoperative errors. On the questionnaires, all 8 surgeons desired a decreased scope diameter and multidirectional visual axis. Four surgeons (50%) experienced eyestrain and 1 experienced double vision. Conclusions: This study showed no reduction in surgical time with 3D versus 2D scope use. Three-dimensional vision decreased the technical errors in creating the wrap, but its clinical merit remains unclear. Decreasing the scope diameter and adding multidirectional vision capabilities are needed for the 3D scope to gain more widespread approval and use in pediatric surgery.

Visualization of three different phases in a multiphase steel by scanning electron microscopy at 1 eV landing energy.

In this study, we investigated an observation technique by super low energy scanning electron microscopy (SLESEM) at below 5 eV and its contrast mechanism for analyzing complex microstructures of a multiphase steel consisting of ferrite, martensite and austenite. With SLESEM at 1 eV, the three phases were observed as different brightness levels, ferrite as the darkest contrast, martensite as the second brightest and austenite as the brightest. These contrasts disappeared at 2 eV or higher. Similar contrasts and phenomena were also observed in the results of low energy electron microscopy (LEEM). According to the energy dependences of the LEEM intensities of the three phases, the threshold energies of the transition from electron reflection to surface impact were determined to be 0.00 eV, 0.15 eV and 0.39 eV for ferrite, martensite and austenite, respectively. These differences in thresholds indicate that the potentials on the surfaces of each phase are different, which is considered to result in the different brightness of each phase. This potential differences are probably due to the contact potentials generated when phases with different work functions contact each other. Although the sample is covered by a thin native oxide film (several nm thickness), the potentials can affect the incident electrons through the oxide film.

Pyogenic liver abscess due to hypervirulent Klebsiella pneumoniae in a 14-year-old boy.

A 14-year-old otherwise healthy boy presented with right-sided back pain following high fever. Abdominal computed tomography scan showed a large liver abscess. Klebsiella pneumoniae (KP) was rapidly identified from peripheral blood using the melting temperature mapping (Tm) method, which enables identification of pathogenic microorganisms within four hours after patient sample collection. He was diagnosed with pyogenic liver abscess (PLA) caused by KP on the day of admission. The KP was the hypervirulent (hv) clinical variant (string test positive, serotype K1, sequence type 23, rmpA and magA positive). After intravenous antibiotic therapy and drainage of the abscess, his condition resolved. The highlights of this case report are a healthy child with hypervirulent Klebsiella pneumoniae liver abscess in Japan and the new Tm mapping method for rapid and accurate identification of the pathogenic microorganism.

Prenatally diagnosed large mediastinal lymphangioma: A case report.

Thoroughly planned labor with immediate postnatal resuscitation and percutaneous decompression is mandatory for a large mediastinal lymphangioma that compromises the cardiopulmonary function, and close observation with the administration of Eppikajutsuto (TJ-28), a Japanese herbal medicine, may be a reasonable treatment, especially when resection of the lesion seems technically challenging.

A patient with peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome, and severe hypoganglionosis associated with a novel SOX10 mutation.

In this report, we present the case of a female infant with peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome, and Hirschsprung disease (PCWH) associated with a novel frameshift mutation (c.842dupT) in exon 5, the last exon of SOX10. She had severe hypoganglionosis in the small intestine and entire colon, and suffered from frequent enterocolitis. The persistence of ganglion cells made both the diagnosis and treatment difficult in the neonatal period. She also showed hypopigmentation of the irises, hair and skin, bilateral sensorineural deafness with hypoplastic inner year, severe demyelinating neuropathy with hypotonia, and diffuse brain hypomyelination. The p.Ser282GlnfsTer12 mutation presumably escapes from nonsense-mediated decay and may generate a dominant-negative effect. We suggest that hypoganglionosis can be a variant intestinal manifestation associated with PCWH and that hypoganglionosis and aganglionosis may share the same pathoetiological mechanism mediated by SOX10 mutations.

Quantitative analysis of angle-selective backscattering electron image of iron oxide and steel.

The contrasts in backscattered electron (BSE) images, such as topographic, channeling and mean atomic number (Z) contrasts, were investigated quantitatively from the cross section of a heat-treated steel sheet using a scanning electron microscope (SEM). High primary electron energy (EP) enhances Z contrast, whereas low EP improves channeling contrast. A high take-off angle (θ; measured from the specimen surface) also enhances Z contrast, whereas low θ improves channeling contrast. When θ becomes very low, topographic information is enhanced and superimposed on channeling contrast due to the tilt effect of BSE. The relationship of the behaviors of the Z contrast and the channeling contrast can be understood by the detection ratio of low-loss electrons (LLEs) to the inelastic BSE components emitted from the sample surface; LLEs contribute to channeling contrast, and their ratio increases with decreasing EP and θ. The systematic results obtained in this study are useful for controlling SEM conditions in order to enhance the target information in BSE images for practical materials of interest.

Extraction of topographic and material contrasts on surfaces from SEM images obtained by energy filtering detection with low-energy primary electrons.

Secondary electron microscope (SEM) images have been obtained for practical materials using low primary electron energies and an in-lens type annular detector with changing negative bias voltage supplied to a grid placed in front of the detector. The kinetic-energy distribution of the detected electrons was evaluated by the gradient of the bias-energy dependence of the brightness of the images. This is divided into mainly two parts at about 500 V, high and low brightness in the low- and high-energy regions, respectively and shows difference among the surface regions having different composition and topography. The combination of the negative grid bias and the pixel-by-pixel image subtraction provides the band-pass filtered images and extracts the material and topographic information of the specimen surfaces.