High-resolution Probe Research Articles

Validation of edge turbulence codes in a magnetic X-point scenario in TORPEX

Transport processes around the magnetic X-point of tokamaks, such as turbulence and mean-field drifts, are scarcely understood. The assessment of the capability of turbulence codes to quantitatively reproduce these dynamics has been hampered by limitations in computational power and available experimental data. In this paper, we present a rigorous validation of full-scale simulations of a newly developed X-point scenario in the basic toroidal plasma device TORPEX, performed with the four state-of-the-art codes FELTOR, GBS, GRILLIX, and STORM. High-resolution Langmuir probe array measurements of various time-averaged and fluctuating quantities and across the entire cross section of TORPEX show that this X-point scenario features the key ingredients of X-point dynamics, such as small-scale fluctuations and background drifts. The codes are able to qualitatively reproduce some characteristics of the time-averaged fields, such as the ion saturation current profiles at mid-height, the plasma up-down asymmetry, and the blob trajectories. A quantitative agreement is found for the background E × B velocity pattern, while the fluctuation levels are generally underestimated typically by factors of 2 or more, and thus, background fluxes are found to dominate over turbulent ones in simulations. The sensitivity of the simulation results on the plasma collisionality and on the position of the sources is tested in GBS, showing a mild effect on the overall quantitative agreement with the experiment. Overall, this validation reveals the challenges to reproduce the plasma dynamics near an X-point and provides a clear path to a quantitative and computationally relatively inexpensive assessment of future developments in turbulence codes.

Rotational energy transfer kinetics of optically centrifuged CO molecules investigated through transient IR spectroscopy and master equation simulations.

A combined experimental and theoretical study of quantum state-resolved rotational energy transfer kinetics of optically centrifuged CO molecules is presented. In the experiments, inverted rotational distributions of CO in rotational states up to J = 80 were prepared using two different optical centrifuge traps, one with the full spectral bandwidth of the optical centrifuge pulses, and one with reduced bandwidth. The relaxation kinetics of the high-J tail of the inverted distribution from each optical trap was determined based on high-resolution transient IR absorption measurements. In parallel studies, master equation simulations were performed using state-to-state rate constants for CO-CO collisions in states up to J = 90, based on data from double-resonance experiments for CO with J = 0-29 and a fit to a statistical power exponential gap model. The model is in qualitative agreement with the observed relaxation profiles, but the observed decay rate constants are smaller than the simulated values by as much as a factor of 10. The observed decay rate constants also have a stronger J-dependence than predicted by the model. The results are discussed in terms of angular momentum and energy conservation, and compared to the observed orientational anisotropy decay kinetics of optically centrifuged CO molecules. Models for rotational energy transfer could be improved by including angular momentum effects.

Evaluation of ultrasonographic findings in adults with cervical lymphadenopathy

ackground and aim: It is very important to distinguish benign and malignant cervical lymph nodes and to make an early diagnosis in terms of treatment and prognosis. Ultrasonography (USG) provides an idea in the diagnosis of reactive or non-reactive lymph nodes but also provides benefits in the differential diagnosis of malignant and benign. It is easily accessible, has high-resolution probes, is inexpensive, does not contain radiation, and serves as a guide in aspiration biopsy when necessary. Although fineneedle aspiration cytology (FNAC) has a high degree of sensitivity and specificity in evaluating cervical lymph nodes, in 20% of patients it may give an ambiguous report that does not contribute to treatment. In this study, ultrasonographic findings of patients with cervical LAP diagnosed with FNAC were evaluated. The value of ultrasonographic examination in diagnosing diseases was emphasized. Materials and methods: In this study, ultrasonographic findings of 178 patients diagnosed with cervical lymphadenopathy by performing FNAC were examined. Ultrasonographic findings, shape, echogenic hilum, nodal matting, L/S ratio and intranodal necrosis characteristics of cervical nodes were evaluated and compared with FNAC diagnoses. Results: It was found statistically significant between a reactive node and ultrasonographic oval shape, metastasis and L/S ratio, presence of echogenic hilus and reactive node, nodal matting finding and tuberculosis (p<0.05). Although the presence of necrosis was detected at a higher rate in metastasis and tuberculosis than lymphoma and reactive node, it was not found to be statistically significant (p>0.05). Conclusion: It is thought that B-mode ultrasonography, which has high specificity and sensitivity, is a successful imaging method and can be used frequently in the differential diagnosis of diseases in all patients presenting with cervical lymphadenopathy. In this way, unnecessary biopsy, excision and further examination examinations are prevented. Keywords: cervical lenfadenopathy; ultrasonographic findings; adults.

Deep Bayesian local crystallography

The advent of high-resolution electron and scanning probe microscopy imaging has opened the floodgates for acquiring atomically resolved images of bulk materials, 2D materials, and surfaces. This plethora of data contains an immense volume of information on materials structures, structural distortions, and physical functionalities. Harnessing this knowledge regarding local physical phenomena necessitates the development of the mathematical frameworks for extraction of relevant information. However, the analysis of atomically resolved images is often based on the adaptation of concepts from macroscopic physics, notably translational and point group symmetries and symmetry lowering phenomena. Here, we explore the bottom-up definition of structural units and symmetry in atomically resolved data using a Bayesian framework. We demonstrate the need for a Bayesian definition of symmetry using a simple toy model and demonstrate how this definition can be extended to the experimental data using deep learning networks in a Bayesian setting, namely rotationally invariant variational autoencoders.

Microring Zone Structure for Near-Field Probes

Recent advances in Surface Plasmon Resonance (SPR) technologies have shown the possibility of transmission enhancement of localized modes propagating through sub-diffraction wide slits and apertures, resulting in the strong near-field focusing of metallic planar nanostructures. This work presents a new approach to the fabrication of high-resolution near-field optical probes using 3D lithography in combination with numerical finite difference time domain (FDTD) simulations. A narrow 500 nm depth of field focus area was observed both by numerical analysis and near field scanning optical microscopy (NSOM) measurements. Further research and optimization are planned in order to achieve subwavelength focal regions and increased signal intensities.

Narrative Review on the Role of Imaging in DDH.

Developmental dysplasia of hip (DDH) represents a spectrum from acetabular dysplasia to fixed dislocation, giving disability through premature osteoarthritis. Most DDH cases continue to present without any known risk factors such as breech presentation, female sex, and family history. Incidence and population-based outcomes of DDH are difficult to reliably establish due to many DDH definitions and classifications using different types of examinations. This review takes a historical perspective on the role of imaging in DDH. Pelvic radiographs (X-Ray) were amongst the first medical images identifying DDH, but these have a limited role in infancy due to absent ossification. In the 1980s, ultrasound led to a large expansion in infant DDH screening. Unfortunately, even for well-trained users, DDH indices on ultrasound generally lack reproducibility, and have led to overdiagnosis of mild DDH. CT and MRI more thoroughly evaluate the 3D hip deformity in DDH, but are costly, less available and involve radiation dose and/or anaesthesia. Recently 3D ultrasound has been used to characterize the 3D deformity of DDH more fully, with improved inter-observer reliability, particularly amongst novice users. 3D ultrasound is also well suited to automated image analysis, but high-resolution 3D probes are costly and not widely available. Combining the latest handheld portable ultrasound probes and artificial intelligence analysis could lead to an inexpensive tool permitting practical mass population screening for DDH. Overall, our understanding of DDH is heavily influenced by the imaging tools used to visualize it and changing quickly with modern technology.

Seeing through metamorphic overprints in Archean granulites: Combined high-resolution thermometry and phase equilibrium modeling of the Lewisian Complex, Scotland

Abstract The Lewisian Complex in northwest Scotland presents a record of the transition from the Neo-Archean to the Paleoproterozoic. However, this record is complicated by a long and varied history after peak metamorphism that has erased and/or partially reset much of the early history of the rocks. Such overprinting is a common feature of Archean granulites and poses a substantial problem when trying to understand the tectonic processes that were active prior to the onset of modern plate tectonics. By combining careful petrography with phase diagram modeling and a range of exchange thermometers we obtain the peak and retrograde temperature history of the Lewisian Complex from a single, well-preserved, representative sample of garnet-bearing mafic granulite. We present the application of high-resolution electron probe microanalysis (HR-EPMA) to characterize sub-micrometer orthopyroxene exsolution lamellae in clinopyroxene. We discuss ways to mitigate issues associated with HR-EPMA including surface contamination, beam drift, standards, and the need to correct for secondary fluorescence effects. The resulting compositions from our HR-EPMA analyses provide an independent measure of the retrograde temperature conditions and can also be used to back-calculate the compositions of clinopyroxene in the peak assemblage. We obtain peak metamorphic conditions for the Lewisian of >11 kbar and >1025 °C, and constrain subsequent metamorphic overprints to 850 °C (Grt-Cpx), 590 °C (Opx-Cpx), and 460 °C (Mag-Ilm). These peak and retrograde temperatures span the range of those found in the literature. Whereas recent phase equilibrium studies assume equilibrium among all preserved high-T minerals, this study considers microstructural and mineral-chemical evidence for corona formation that reflects post-peak decompression with partial equilibration at ~850 °C, as recognized in some earlier studies.

Ultrasonography for noninvasive and real-time evaluation of peri-implant soft and hard tissue: a case series

BackgroundThe diagnosis of soft and hard tissue at dental implants will be challenging in the future, as high prevalence of mucositis and peri-implantitis were described in the population. Ultrasonography is a promising non-invasive, inexpensive, painless, and radiation-free method for imaging hard and soft tissue at implants, especially an ultrasound device with a 25-MHz probe demonstrating a high correlation between ultrasound, clinical, and radiological measurements.Case presentationThe following case series demonstrates the use of ultrasonography with high spatial resolution probe in patients with dental implants affected by soft tissue recession and/or crestal bone loss.ConclusionThese ultrasound images can provide valuable additional information for the assessment of peri-implant soft and hard tissue.

Nanoenabled Bioelectrical Modulation.

ConspectusStudying the formation and interactions between biological systems and artificial materials is significant for probing complex biophysical behaviors and addressing challenging biomedical problems. Bioelectrical interfaces, especially nanostructure-based, have improved compatibility with cells and tissues and enabled new approaches to biological modulation. In particular, free-standing and remotely activated bioelectrical devices demonstrate potential for precise biophysical investigation and efficient clinical therapies. Interacting with single cells or organelles requires devices of sufficiently small size for high resolution probing. Nanoscale semiconductors, given their diverse functionalities, are promising device platforms for subcellular modulation. Tissue-level modulation requires additional consideration regarding the device’s mechanical compliance for either conformal contact with the tissue surface or seamless three-dimensional (3D) biointegration. Flexible or even open-framework designs are essential in such methods. For chronic organ integration, the highest level of biocompatibility is required for both the materials and device configurations. Additionally, a scalable and high-throughput design is necessary to simultaneously interact with many individual cells in the organ. The physical, chemical, and mechanical stabilities of devices for organ implantation may be improved by ensuring matching of mechanical behavior at biointerfaces, including passivation or resistance designs to mitigate physiological impacts, or incorporating self-healing or adaptative properties.Recent research demonstrates principles of nanostructured material designs that can be used to improve biointerfaces. Nanoenabled extracellular interfaces were frequently used for either electrical or remote optical modulation of cells and tissues. In particular, methods are now available for designing and screening nanostructured silicon, especially chemical vapor deposition (CVD)-derived nanowires and two-dimensional (2D) nanostructured membranes, for biological modulation in vitro and in vivo. For intra- and intercellular biological modulation, semiconductor/cell composites have been created through the internalization of nanowires, and such cellular composites can even integrate with living tissues. This approach was demonstrated for both neuronal and cardiac modulation.At a different front, laser-derived nanocrystalline semiconductors showed electrochemical and photoelectrochemical activities, and they were used to modulate cells and organs. Recently, self-assembly of nanoscale building blocks enabled fabrication of efficient monolithic carbon-based electrodes for in vitro stimulation of cardiomyocytes, ex vivo stimulation of retinas and hearts, and in vivo stimulation of sciatic nerves.Future studies on nanoenabled bioelectrical modulation should focus on improving efficiency and stability of current and emerging technologies. New materials and devices can access new interrogation targets, such as subcellular structures, and possess more adaptable and responsive properties enabling seamless integration. Drawing inspiration from energy science and catalysis can help in such progress and open new avenues for biological modulation. The fundamental study of living bioelectronics could yield new cellular composites for diverse biological signaling control. In situ self-assembled biointerfaces are of special interest in this area as cell type targeting can be achieved.

High-resolution probe design for measuring the dielectric properties of human tissues

BackgroundIn order to use the microwave to measure the dielectric constant of the human body and improve the measurement resolution, a small near-field probe working at 915 MHz is designed in this paper.MethodBased on the electric small loop antenna model loaded by the spiral resonator (SR), a small near-field probe was designed. The probe model is designed and optimized by the HFSS (high frequency structure simulator) software. The human tissues were tested by the manufactured probe and the relationship between the S11 parameters of the probe and the human tissues was analyzed.Results and conclusionsA probe with small size was designed and fabricated, with the overall size of 10.0 mm × 12.0 mm × 0.8 mm. The probe has a good performance with a 30.7 dB return loss, a 20 MHz bandwidth at the resonance point, and a distance resolution of 10 mm. Due to the small size and good resolution of the probe, it can be used in the measurement of human tissues.

Revisiting the Bøggild Intergrowth in Iridescent Labradorite Feldspars: Ordering, Kinetics, and Phase Equilibria

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.

Investigation of endothelial dysfunction and arterial stiffness in multisystem inflammatory syndrome in children.

Severe acute respiratory syndrome coronavirus 2 infection can result in multisystem inflammatory syndrome in children (MIS-C). MIS-C can lead to myocardial dysfunction, heart failure, and multiorgan failure; the primary finding is hyperinflammation. Endothelial dysfunction has not been evaluated in patients with MIS-C. We investigated endothelial dysfunction and arterial stiffness parameters in patients with MIS-C. The study included 38 pediatric patients (20 males and 18 females aged 4–17 years, mean age 8.89 years) with MIS-C. Thirty-eight age- and sex-matched healthy individuals were enrolled as the control group. Systolic and diastolic ventricular measurements and systolic and diastolic measurements of ascending aorta diameter were performed by M-mode echocardiography. Endothelial dysfunction was evaluated using flow-mediated dilation by measuring the brachial artery diameter with a high-resolution probe. The MIS-C group had lower flow-mediated dilation than did the controls. The MIS-C group had decreased aortic strain and aortic distensibility values and correlations between decreased flow-mediated dilation and reduced aortic strain, aortic distensibility, and reduced ejection fraction.Conclusion: The results show that patients with MIS-C had endothelial dysfunction and arterial stiffness. Furthermore, the degree of endothelial dysfunction correlated with reduced ejection fractions. What is Known: •Endothelial dysfunction and arterial stiffness are unknown in patients with MIS-C. •The effect of endothelial dysfunction and arterial stiffness on decreased cardiac function is unknown. What is New: •MIS-C patients have endothelial dysfunction and arterial stiffness. •There is a link between left ventricular dysfunction and reduced endothelial dysfunction in patients with MIS-C.

Stability and stoichiometry of L12 Al3(Sc,Zr) dispersoids in Al-(Si)-Sc-Zr alloys

This work studies the impact of adding 0.5 wt.% Si on the formation of Al3(Sc,Zr) L12 precipitates in a lean Al-Sc-Zr alloy. Precipitation kinetics are significantly accelerated when ageing at 300 and 375 °C in the presence of Si. At 375 °C, peak hardness occurs in a few minutes and is maintained up to 200 h at 375 °C . High resolution TEM reveals the presence of very fine core-shell L12 dispersoids ~5 nm in size that remain stable for up to 200 h at 375 °C. Using high-resolution energy dispersive X-ray spectroscopy (EDX) and atom probe tomography (APT), the presence of Si and Fe is detected in the core of the dispersoids, where their content decreases as a function of ageing time. Similar Si and Fe compositions were observed inside the dispersoids for both alloys regardless of bulk Si content. Both Si and Fe are found to have preference for the Al site in the L12 structure, which is supported by density functional theory (DFT) calculations. DFT also explains the decrease of Si and Fe over time, showing that there is no thermodynamic driving force for either Si or Fe to be present in the L12. Instead Si and Fe are found to play a crucial role at the early stages of clustering, but are expelled from the particles when they stabilise into L12 structures.

On the reversibility of the α2/ωo phase transformation in a high Nb containing TiAl alloy during high temperature deformation

• The reverse transformation ω o →α 2 occurs during high-temperature deformation. • The tilt angles between neighbouring α 2 grains change from 56° to mostly 60° after annealing. • A mixed structure of α 2 +ω o phase replaced the original α 2 laths in the annealed sample. The transformations between the phases α 2 (Ti 3 Al) and ω o were investigated in a lamellar multiphase titanium aluminide alloy based on γ (TiAl). The paper complements an earlier investigation performed on the same material in which the importance of deformation-induced twin structures for the α 2 →ω o transformation was demonstrated. The present study shows that the reverse transformation ω o →α 2 can also occur during high-temperature deformation. The transformation is probably triggered by constraint stresses, which exist between the different constituents due to the crystalline mismatch. The combined operation of mechanical twinning of the α 2 phase and the reversible transformation fully converts the α 2 lamellae into a mixture of α 2 and ω o . This conversion greatly reduces the mechanical anisotropy existing in former α 2 lamellae. Regarding the technical use of the alloy, the stability of the converted structure with respect to further annealing was also examined. The reported processes occur at the nano-meter and sub nano-meter scale, thus, advanced characterization techniques were applied, such as high-resolution transmission electron microscopy (HRTEM) and atom probe tomography (APT).

Efficacy of Shear Wave Elastography in the Differentiation of Acute and Subacute Deep Venous Thrombosis.

It is important to know the age of clot formation to determine an appropriate treatment for deep vein thrombosis (DVT). The present study aims to differentiate between acute and subacute DVT using the shear wave elastography (SWE) technique. Patients with complaints no longer than 4 weeks and who were found to have early-stage (acute-subacute) thrombus on ultrasound (US) between January 2020 and May 2020 were included in the study. All of the patients underwent SWE using a Philips Healthcare EPIQ 5 Ultrasound System Inc. device with a high-resolution linear US probe (eL18-4, 22-2 MHz). Included in the study were 50 patients, including 23 with acute DVT and 27 with subacute DVT. Of the patients, 22 were women and 28 were men, and the mean age was 46.32 ± 11.33 years (range: 24-74 years). The mean SWE value was 2.63± 0.16 (2.39-2.96) in patients with acute DVT and 3.34± 0.31 (2.65-3.88) in patients with subacute DVT. The findings were statistically significant in the comparison of the 2 groups using an independent samples t test (P < 0.001). In the receiver operating characteristic analysis, the area under the curve was found to be 97.6%. When the cutoff value was taken as 2.85 according to the area under the curve, sensitivity was found to be 96.3%, and specificity was 91.3%. Thrombus stage plays a critical role in treatment decisions in DVT in the lower extremities. The present study reveals that the shear wave US elastography technique can be used to discriminate between acute and subacute DVT.

Double sample holder for efficient high-resolution studies of an insulator and a metal surface.

A double sample holder supporting both a metal sample and an insulator crystal for high-resolution scanning probe microscopy experiments is described. The metal sample serves as a substrate for tip preparation and tip functionalization to efficiently and reliably enable high-resolution studies of the adjacent insulator surface. Imaging of Ag(111)/mica, Au(111)/mica, CaF2(111), and calcite(104) surfaces is demonstrated at 5K, including images on calcite(104) produced with a CO terminated tip, which was prepared on the adjacent metal sample.

Polythiophene/Zinc Oxide/Graphene Oxide Ternary Photocatalyst: synthesis, characterization and application

ABSTRACT In this study, polythiophene-zinc oxide-graphene oxide (PTh-ZnO-GO) nanocomposite photocatalysts have been successfully synthesized via a green method followed by in-situ chemical polymerization. The catalysts were characterized by Fourier transform infrared analysis, powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, Thermogravimetric analysis, four-point probe and UV-vis diffuse reflectance spectrum. FT-IR bands confirmed the presence of PTh, ZnO and GO in the PTh-ZnO-GO nanocomposites. The PTh-ZnO-GO composites exhibit higher photocatalytic activities compared to pure ZnO and GO and also binary PTh-GO and ZnO-GO composite under irradiation and degradation ability of PTh-ZnO-GO is about 38 times higher than that pure component such as GO. Thermogravimetric analysis and electrical conductivity measurement also showed that degradation temperature improved about 20◦ C in ternary hybrids and electrical conductivity increased in the range of one order of magnitude. Therefore, PTh-ZnO-GO nanocomposite is a solar light-active photocatalyst which can be used in the degradation of organic pollutants.

Intestinal ultrasound in pediatrics

Ultrasonography is the imaging technique of choice for studying the digestive tract in paediatric patients from the neonatal period to adolescence. Its dynamic character, absence of radiation, and scant preparation required make ultrasonography preferable to contrast-enhanced fluoroscopy, computed tomography, or magnetic resonance imaging. Technical advances in ultrasound, including high-resolution multifrequency probes, panoramic studies, colour Doppler, Doppler with microvascularization, elastography, and contrast agents for use in children, have increased the sensitivity and specificity of this technique.Intestinal ultrasound is indicated for conditions with diverse etiologies and pathogenesis: congenital, infectious, inflammatory, tumor-related, and vascular. Knowledge of embryological development and the normal characteristics of the digestive tract help in identifying, recognizing, and interpreting the ultrasound findings of the different conditions in paediatric patients.This paper aims to show the indications for ultrasound studies of the digestive tract in children, the findings on these studies, and the management of the most common gastrointestinal conditions in paediatric patients.

Characterization of carbon materials using high-resolution scanning probe microscopy

Characterization of carbon materials using high-resolution scanning probe microscopy

Insights on the mechanism of Fe doped ZnO for tightly-bound extracellular polymeric substances tribo-catalytic degradation: The role of hydration layers at the interface

The control of interfacial microbial pollution is of great significance for water safety. Herein, the tribo-catalysis ability of zinc oxide (ZnO) has been investigated, which can realize the control of tightly-bound extracellular polymeric substances (T-EPS) in water under dark environment. The DFT calculation proves the Fe doping introduces the impurity level and decreases the work function from 5.071 eV to 5.045 eV, improves the charge separation of ZnO, and eventually enhances the catalytic reaction efficiency. Characterizing the catalytic reaction process by three-dimensional fluorescence (3D EEM) and fluorescence regional integration (FRI) method, it is found that the T-EPS solution can be degraded 75.8% by Fe-ZnO in 12 min, while ZnO can only degrade 32.2%. Combining with high-resolution scanning probe microscope (HR-SPM) and attenuated total reflection method (ATR-FTIR), hydration layers consist with hydroxyl layer (∼0.23 nm) and water molecular layer (∼0.27 nm) are observed at the interface between Fe-ZnO and T-EPS solution, and terminal hydroxyl group (OHt) is considered to be the active site for the generation of radicals. This study provides an idea for exploring the mechanism of tribo-catalytic reaction and shows its application prospect in the field of microbial inhibition in water.