The first mobile photon-counting detector CT: the human images and technical performance study.

Objective. The purpose of this study is to assess its human images and its unique capabilities such as the 'on demand' higher spatial resolution and multi-spectral imaging of photon-counting-detector (PCD)-CT.Approach. In this study, the FDA 510(k) cleared mobile PCD-CT (OmniTom Elite) was used. To this end, we imaged internationally certified CT phantoms and a human cadaver head to evaluate the feasibility of high resolution (HR) and multi-energy imaging. We also demonstrate the performance of PCD-CT via first-in-human imaging by scanning three human volunteers.Main results. At the 5 mm slice thickness, routinely used in diagnostic head CT, the first human PCD-CT images were diagnostically equivalent to the EID-CT scanner. The HR acquisition mode of PCD-CT achieved a resolution of 11 line-pairs (lp)/cm as compared to 7 lp cm-1using the same kernel (posterior fossa-kernel) in the standard acquisition mode of EID-CT. For the quantitative multi-energy CT performance, the measured CT numbers in virtual mono-energetic images (VMI) of iodine inserts in the Gammex Multi-Energy CT phantom (model 1492, Sun Nuclear Corporation, USA) matched the manufacturer reference values with mean percent error of 3.25%. Multi-energy decomposition with PCD-CT demonstrated the separation and quantification of iodine, calcium, and water.Significance. PCD-CT can achieve multi-resolution acquisition modes without physically changing the CT detector. It can provide superior spatial resolution compared with the standard acquisition mode the conventional mobile EID-CT. Quantitative spectral capability of PCD-CT can provide accurate, simultaneous multi-energy images for material decomposition and VMI generation using a single exposure.

Characterization of Silver Nanowire-Based Transparent Electrodes Obtained Using Different Drying Methods.

Metal-based transparent top electrodes allow electronic devices to achieve transparency, thereby expanding their application range. Silver nanowire (AgNW)-based transparent electrodes can function as transparent top electrodes, owing to their excellent conductivity and transmittance. However, they require a high-temperature drying process, which damages the bottom functional layers. Here, we fabricated two types of AgNW-based electrodes using the following three drying methods: thermal, room-temperature, and vacuum. Thereafter, we investigated the variation in their morphological, electrical, and optical characteristics as a function of the drying method and duration. When the AgNW-exposed electrode was dried at room temperature, it exhibited a high surface roughness and low conductivity, owing to the slow solvent evaporation. However, under vacuum, it exhibited a similar electrical conductivity to that achieved by thermal drying because of the decreased solvent boiling point and fast solvent evaporation. Conversely, the AgNW-embedded electrodes exhibited similar roughness values and electrical conductivities regardless of the drying method applied. This was because the polymer shrinkage during the AgNW embedding process generated capillary force and improved the interconnectivity between the nanowires. The AgNW-based electrodes exhibited similar optical properties regardless of the drying method and electrode type. This study reveals that vacuum drying can afford transparent top electrodes without damaging functional layers.

Transparent Soft Actuators/Sensors and Camouflage Skins for Imperceptible Soft Robotics.

The advent of soft robotics has led to great advancements in robots, wearables, and even manufacturing processes by employing entirely soft-bodied systems that interact safely with any random surfaces while providing great mechanical compliance. Moreover, recent developments in soft robotics involve advances in transparent soft actuators and sensors that have made it possible to construct robots that can function in a visually and mechanically unobstructed manner, assisting the operations of robots and creating more applications in various fields. In this aspect, imperceptible soft robotics that mainly consist of optically transparent imperceptible hardware components is expected to constitute a new research focus in the forthcoming era of soft robotics. Here, the recent progress regarding extended imperceptible soft robotics is provided, including imperceptible transparent soft robotics (transparent soft actuators/sensors) and imperceptible nontransparent camouflage skins. Their principles, materials selections, and working mechanisms are discussed so that key challenges and perspectives in imperceptible soft robotic systems can be explored.

Laser-Induced Crystalline-Phase Transformation for Hematite Nanorod Photoelectrochemical Cells.

Generally, a high-temperature postannealing process is required to enhance the photoelectrochemical (PEC) performance of hematite nanorod (NR) photoanodes. However, the thermal annealing time is limited to a short duration as thermal annealing at high temperatures can result in some critical problems, such as conductivity degradation of the fluorine-doped tin oxide film and deformation of the glass substrate. In this study, selective laser processing is introduced for hematite-based PEC cells as an alternative annealing process. The developed laser-induced phase transformation (LIPT) process yields hematite NRs with enhanced optical, chemical, and electrical properties for application in hematite NR-based PEC cells. Owing to its improved properties, the LIPT-processed hematite NR PEC cell exhibits an enhanced water oxidation performance compared to that processed by the conventional annealing process. As the LIPT process is conducted under ambient conditions, it would be an excellent alternative annealing technique for heat-sensitive flexible substrates in the future.

Correction: Recent progress in controlled nano/micro cracking as an alternative nano-patterning method for functional applications.

Correction for 'Recent progress in controlled nano/micro cracking as an alternative nano-patterning method for functional applications' by Jinwook Jung et al., Nanoscale Horiz., 2020, DOI: .

Recent progress in controlled nano/micro cracking as an alternative nano-patterning method for functional applications.

Generally, cracking occurs for many reasons connected to uncertainties and to the non-uniformity resulting from intrinsic deficiencies in materials or the non-linearity of applied external (thermal, mechanical, etc.) stresses. However, recently, an increased level of effort has gone into analyzing the phenomenon of cracking and also into methods for controlling it. Sophisticated manipulation of cracking has yielded various cutting-edge technologies such as transparent conductors, mechanical sensors, microfluidics, and energy devices. In this paper, we present some of the recent progress that has been made in controlling cracking by giving an overview of the fabrication methods and working mechanisms used for various mediums. In addition, we discuss recent progress in the various applications of methods that use controlled cracking as an alternative to patterning tools.

Evidence of Stress Development as a Source of Driving Force for Grain-Boundary Migration in a Ni Bicrystalline TEM Specimen.

In a previous study, using high-resolution transmission electron microscopy (HRTEM), we examined grain-boundary migration behavior in a Ni bicrystal. A specimen for transmission electron microscopy (TEM) was prepared using focused ion beam. The Ni lamella in the specimen was composed of two grains with surface normal directions of [1 0 0] and [1 1 0]. As the lamella was heated to 600 °C in a TEM, it was subjected to compressive stresses. The stress state of the Ni lamella approximated to the isostress condition, which was confirmed by a finite element method. However, the stress development was not experimentally confirmed in the previous study. In the present study, we present an observation of stacking faults with a length of 40-70 nm at the grain boundary as direct evidence of the stress development.

Sensitive Wearable Temperature Sensor with Seamless Monolithic Integration.

Accurate temperature field measurement provides critical information in many scientific problems. Herein, a new paradigm for highly sensitive, flexible, negative temperature coefficient (NTC) thermistor-based artificial skin is reported, with the highest temperature sensing ability reported to date among previously reported NTC thermistors. This artificial skin is achieved through the development of a novel monolithic laser-induced reductive sintering scheme and unique monolithic structures. The unique seamless monolithic structure simultaneously integrates two different components (a metal electrode and metal oxide sensing channel) from the same material at ambient pressure, which cannot be achieved by conventional heterogeneous integration through multiple, complex steps of photolithography or vacuum deposition. In addition to superior performance, electronic skin with high temperature sensitivity can be fabricated on heat-sensitive polymer substrates due to the low-temperature requirements of the process. As a proof of concept, temperature-sensitive artificial skin is tested with conformally attachable physiological temperature sensor arrays in the measurement of the temperatures of exhaled breath for the early detection of pathogenic progression in the respiratory system. The proposed highly sensitive flexible temperature sensor and monolithic selective laser reductive sintering are expected to greatly contribute to the development of essential components in various emerging research fields, including soft robotics and healthcare systems.

Stretchable/flexible silver nanowire Electrodes for energy device applications.

Research on sustainable and high-efficiency energy devices has recently emerged as an important global issue. These devices are now moving beyond the form of a bulk, rigid platform to a portable, flexible/stretchable format that is easily available in our daily lives. Similar to the development of an active layer for the production of next-generation energy devices, the fabrication of flexible/stretchable electrodes for the easy flow of electrons is also very important. Silver nanowire electrodes have high electronic conductivity even in a flexible/stretchable state due to their high aspect ratio and percolation network structures compared to conventional electrodes. Herein, we summarize the research in the field of flexible/stretchable electronics on energy devices fabricated using silver nanowires as the electrodes. Additionally, for a systematic presentation of the current research trends, this review classifies the surveyed research efforts into the categories of energy production, storage, and consumption.

Mechano-thermo-chromic device with supersaturated salt hydrate crystal phase change.

Active control of transparency/color is the key to many functional optoelectric devices. Applying an electric field to an electrochromic or liquid crystal material is the typical approach for optical property control. In contrast to the conventional electrochromic method, we developed a new concept of smart glass using new driving mechanisms (based on mechanical stimulus and thermal energy) to control optical properties. This mechano-thermo-chromic smart glass device with an integrated transparent microheater uses a sodium acetate solution, which shows a unique marked optical property change under mechanical impact (mechanochromic) and heat (thermochromic). Such mechano-thermo-chromic devices may provide a useful approach in future smart window applications that could be operated by external environment conditions.

Directional Shape Morphing Transparent Walking Soft Robot.

Transparency in electronics can provide extra functionality and esthetic impression. Transparency plays an important role in accurate soft robot control because one can directly observe target surface condition that is usually blocked by a robot's body. Nowadays, demand for soft actuators has been rapidly increasing because soft robots have attracted much attention recently. However, conventional soft actuators are usually nontransparent with simple isotropic bending, limited performance, and limited functionality. To overcome such limitations of current soft robots, we developed a novel soft shape morphing thin film actuator with new functionalities such as high transparency and unique directional responses to allow complex behavior by integrating a transparent metal nanowire heater. A figure of merit was developed to evaluate the performance and derive an optimum design configuration for the transparent actuator with enhanced performance. As a proof of concept, various transparent soft robots such as transparent gripper, Venus flytrap, and transparent walking robot were demonstrated. Such transparent directional shape morphing actuator is expected to open new application fields and functionalities overcoming limitations of current soft robots.

Analysis of ovarian volume of Korean children and adolescents at magnetic resonance imaging.

BACKGROUND: Knowledge of ovarian volume is important for diagnostic evaluations; however, normal ovarian volume studies on children and adolescents are lacking. OBJECTIVE: This study aimed to analyze age-specific ovarian volume and identify the diverse factors that contribute to ovarian diagnoses. MATERIALS AND METHODS: We retrospectively enrolled 180 patients (0-18 years of age) with normal ovaries who underwent magnetic resonance imaging (MRI) between 2010 and 2018. MRI sequences included coronal and axial T2-weighted turbo spin echo (TSE) images and coronal T1-weighted TSE images. Ovarian volume was calculated by the standard ellipsoid formula. Age-specific ovarian volume, height, weight, height-adjusted total ovarian volume and body mass index were obtained. Linear regression analysis was used to predict ovarian volume. RESULTS: Six age groups (infant; early and late child, and early, middle and late adolescent) were described. The early adolescent group (10-12 years) had the highest rate of increase. In the middle adolescent period (13-15 years), the curve of ovarian volume appeared flat. CONCLUSION: Our findings provide age-specific references for ovarian volume.

Moiré-Free Imperceptible and Flexible Random Metal Grid Electrodes with Large Figure-of-Merit by Photonic Sintering Control of Copper Nanoparticles.

Flexible micro/nano metal grid transparent conductors emerged as an alternative to the fragile/rigid indium tin oxide electrode. They are usually fabricated by the combination of the conventional photolithography and the vacuum deposition of regular metal grid patterns, however, seriously suffer from moiré and starburst problems induced by periodic regular pattern structures. In this paper, we demonstrated flexible and imperceptible random copper microconductors with an extremely high figure-of-merit (∼2000) by the thermal conduction layer-assisted photonic sintering of copper nanoparticles without damages in the plastic substrate. This process can be easily applied to complicated structures and surfaces including a random pattern which is imperceptible and free of interferences. As a proof-of-concept, a transparent windshield defogger in a car was demonstrated with a Cu transparent random conductor at an extreme and reversible fogging state.

Self-assembled stretchable photonic crystal for a tunable color filter.

In this Letter, we report the development of a continuously tunable color filter based on a self-assembled isotropically stretchable microbead monolayer. Spreading equidistantly upon the application of lateral strain, the isotropically stretchable monolayer serves as a dynamic diffraction grating whose diffraction angle can be mechanically modulated. Combined with a simple spatial filtering scheme, the spectra of the filtered light are solely controlled by external strain (up to 32% radial strain) to cover a broad visible spectrum. Through a finite-difference time-domain far-field diffraction simulation, we validate the working principle of the proposed color filter. The proposed continuously tunable color filter is expected to open original applications in next-generation display field.

ZnO/CuO/M (M = Ag, Au) Hierarchical Nanostructure by Successive Photoreduction Process for Solar Hydrogen Generation.

To date, solar energy generation devices have been widely studied to meet a clean and sustainable energy source. Among them, water splitting photoelectrochemical cell is regarded as a promising energy generation way for splitting water molecules and generating hydrogen by sunlight. While many nanostructured metal oxides are considered as a candidate, most of them have an improper bandgap structure lowering energy transition efficiency. Herein, we introduce a novel wet-based, successive photoreduction process that can improve charge transfer efficiency by surface plasmon effect for a solar-driven water splitting device. The proposed process enables to fabricate ZnO/CuO/Ag or ZnO/CuO/Au hierarchical nanostructure, having an enhanced electrical, optical, photoelectrochemical property. The fabricated hierarchical nanostructures are demonstrated as a photocathode in the photoelectrochemical cell and characterized by using various analytic tools.

Highly Stretchable and Transparent Electromagnetic Interference Shielding Film Based on Silver Nanowire Percolation Network for Wearable Electronics Applications.

Future electronics are expected to develop into wearable forms, and an adequate stretchability is required for the forthcoming wearable electronics considering various motions occurring in human body. Along with stretchability, transparency can increase both the functionality and esthetic features in future wearable electronics. In this study, we demonstrate, for the first time, a highly stretchable and transparent electromagnetic interference shielding layer for wearable electronic applications with silver nanowire percolation network on elastic poly(dimethylsiloxane) substrate. The proposed stretchable and transparent electromagnetic interference shielding layer shows a high electromagnetic wave shielding effectiveness even under a high tensile strain condition. It is expected for the silver nanowire percolation network-based electromagnetic interference shielding layer to be beyond the conventional electromagnetic interference shielding materials and to broaden its application range to various fields that require optical transparency or nonplanar surface environment, such as biological system, human skin, and wearable electronics.

Characterization of Edge Contact: Atomically Resolved Semiconductor-Metal Lateral Boundary in MoS2.

Despite recent efforts for the development of transition-metal-dichalcogenide-based high-performance thin-film transistors, device performance has not improved much, mainly because of the high contact resistance at the interface between the 2D semiconductor and the metal electrode. Edge contact has been proposed for the fabrication of a high-quality electrical contact; however, the complete electronic properties for the contact resistance have not been elucidated in detail. Using the scanning tunneling microscopy/spectroscopy and scanning transmission electron microscopy techniques, the edge contact, as well as the lateral boundary between the 2D semiconducting layer and the metalized interfacial layer, are investigated, and their electronic properties and the energy band profile across the boundary are shown. The results demonstrate a possible mechanism for the formation of an ohmic contact in homojunctions of the transition-metal dichalcogenides semiconductor-metal layers and suggest a new device scheme utilizing the low-resistance edge contact.

Infrared photoreflectance investigation of resonant levels and band edge structure in InSb.

Temperature-dependent infrared photoreflectance (PR) is employed on InSb for clarifying resonant levels (RLs) and band edge structure. Abundant PR features are well resolved around the bandgap and are verified to be of electronic inter-level transitions rather than the Franz-Keldysh oscillations. The evolution of the critical energies with temperature reveals the nature of the PR processes, from which one acceptor RL, two donor RLs, and a shallow acceptor level are quantitatively identified, and a detailed band edge structure is derived. The results show that temperature-dependent infrared PR analysis can serve as an efficient vehicle for clarifying both bound and resonant levels in semiconductors.

Detection of genetic variation using dual-labeled peptide nucleic acid (PNA) probe-based melting point analysis.

BACKGROUND: Thermal denaturation of probe-target hybrid is highly reproducible, and which makes probe melting point analysis reliable in the detection of mutations, polymorphisms and epigenetic differences in DNA. To improve resolution of these detections, we used dual-labeled (quencher and fluorescence), full base of peptide nucleic acid (PNA) probe for fluorescence probe based melting point analysis. Because of their uncharged nature and peptide bond-linked backbone, PNA probes have more favorable hybridization properties, which make a large difference in the melting temperature between specific hybridization and partial hybridization. RESULTS: Here, we have shown that full base dual-labeled PNA is apt material for fluorescence probe-based melting point analysis with large difference in the melting temperature between full specific hybridization and that of partial hybridization, including insertion and deletion. In case of narrowly distributed mutations, PNA probe effectively detects three mutations in a single reaction tube with three probes. Moreover, we successfully diagnose virus analogues with amplification and melting temperature signal. Lastly, Melting temperature of PNA oligomer can be easily adjusted just by adding gamma-modified PNA probe. CONCLUSIONS: The PNA probes offer advantage of improved flexibility in probe design, which could be used in various applications in mutation detection among a wide range of spectrums.

The translation elongation factor eEF-1Bß1 is involved in cell wall biosynthesis and plant development in Arabidopsis thaliana.

The eukaryotic translation elongation factor eEF-1Bß1 (EF1Bß) is a guanine nucleotide exchange factor that plays an important role in translation elongation. In this study, we show that the EF1Bß protein is localized in the plasma membrane and cytoplasm, and that the transcripts should be expressed in most tissue types in seedlings. Sectioning of the inflorescence stem revealed that EF1Bß predominantly localizes to the xylem vessels and in the interfascicular cambium. EF1Bß gene silencing in efß caused a dwarf phenotype with 38% and 20% reduction in total lignin and crystalline cellulose, respectively. This loss-of-function mutant also had a lower S/G lignin monomer ratio relative to wild type plants, but no changes were detected in a gain-of-function mutant transformed with the EF1Bß gene. Histochemical analysis showed a reduced vascular apparatus, including smaller xylem vessels in the inflorescence stem of the loss-of-function mutant. Over-expression of EF1Bß in an eli1 mutant background restored a WT phenotype and abolished ectopic lignin deposition as well as cell expansion defects in the mutant. Taken together, these data strongly suggest a role for EF1Bß in plant development and cell wall formation in Arabidopsis.