High-temperature corrosion of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho)environmental barrier coating materials by volcanic ash

Rare-earth silicates are promising environmental barrier coatings(EBCs)that can protect SiC_(f)/Si C_(m)substrates in next-genera tion gas turbine blades.Notably,RE_(2)Si_(2)O_(7)(RE=Yb and Ho)shows potential as an EBC due to its coefficient of thermal expansion(CTE)compatible with substrates and high resistance to water vapor corrosion.The target operating temperature for next-generation tur bine blades is 1400°C.Corrosion is inevitable during adhesion to molten volcanic ash,and thus,understanding the corrosion behavior o the material is crucial to its reliability.This study investigates the high-temperature corrosion behavior of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho).Samples were prepared using a solid-state reaction and hot-press method.They were then exposed to volcanic ash at 1400°C for 224,and 48 h.After 48 h of exposure,volcanic ash did not react with Yb_(2)Si_(2)O_(7)but penetrated its interior,causing damage.Meanwhile Ho_(2)Si_(2)O_(7)was partially dissolved in the molten volcanic ash,forming a reaction zone that prevented volcanic ash melts from penetrating the interior.With increasing heat treatment time,the reaction zone expanded,and the thickness of the acicular apatite grains increased The Ca:Si ratios in the residual volcanic ash were mostly unchanged for Yb_(2)Si_(2)O_(7)but decreased considerably over time for Ho_(2)Si_(2)O_(7).Th Ca in volcanic ash was consumed and formed apatite,indicating that RE^(3+)ions with large ionic radii(Ho>Yb)easily precipitated apatit from the volcanic ash.

The Classification to Stationary Process of Tidal Motion Observed at the Time of Kuroshio’s Meandering

The tide level displays information about the state of the sea current and the tidal motion. The tide level of the southern coast of Japan Island is affected strongly by Kuroshio Current flowing in the western part of North Pacific Ocean. When Kuroshio takes the straight path and flow along the Japan Islands, the tide level increases, and it is calculated from two tide level data observed at Kushimoto and Uragami in the southern part of Kii Peninsula. In contrast, the tide level decreases at the time when Kuroshio leaves from the Japan Islands. In this paper, the hourly tidal data are analyzed using the Autocorrelation Function (ACF) and the Mutual Information (MI) and the phase trajectories at first. We classify the results into 5 types of tidal motion. Each categorized type is investigated and characterized precisely using the mean tide level and the unit root test (ADF test) next. The frequency of the type having unstable tidal motion increases when the Kuroshio Current is non-meandering or in a transition state or the tide level is high, and the type shows a non-stationary process. On the other hand, when the Kuroshio Current meanders, the tidal motion tends to take a periodical and stable state and the motion is a stationary process. Though it is not frequent, we also discover a type of stationary and irregular tidal motion.

Customized 3D-printed occluders enabling the reproduction of consistent and stable heart failure in swine models

Reproducibility of clinical output is important when investigating therapeutic efficacy in pre-clinical animal studies.Due to its physiological relevance,a swine myocardial infarction(MI)model has been widely used to evaluate the effectiveness of stem cells or tissue-engineered constructs for ischemic heart diseases.Several methods are used to induce MI in the swine model.However,it is difficult,using these approaches,to obtain a similar level of functional outcomes from a group of animals due to interpersonal variation,leading to increased experimental cost.Hence,in order to minimize human intervention,we developed an approach to use a customized occluder that has dimensional similarities with that of the coronary artery of animals in the case of the swine model.We carried out angiography to measure the diameter of the middle left anterior descending artery of each individual animal to fabricate the customized occluder using a 3D-printing system.The fabricated occluder contained a central hole smaller than that of the targeted middle left anterior descending artery to mimic an atherosclerotic coronary artery that has an approximately 20%blocked condition.Interestingly,the 3D-printed occluder can provide continuous blood flow through the central pore,indicating a high survival rate(88%)of up to 28 days post-operation.This method showed the possibility of creating consistent myocardial infarction induction as compared to the conventional representative closed-chest method(50%survival rate),thus highlighting how our method can have a profound effect on accelerating reliable experiments for developing new therapeutic approaches to ischemic heart diseases.

Bifurcation Analysis of Reduced Network Model of Coupled Gaussian Maps for Associative Memory

This paper proposes an associative memory model based on a coupled system of Gaussian maps. A one-dimensional Gaussian map describes a discrete-time dynamical system, and the coupled system of Gaussian maps can generate various phenomena including asymmetric fixed and periodic points. The Gaussian associative memory can effectively recall one of the stored patterns, which were triggered by an input pattern by associating the asymmetric two-periodic points observed in the coupled system with the binary values of output patterns. To investigate the Gaussian associative memory model, we formed its reduced model and analyzed the bifurcation structure. Pseudo-patterns were observed for the proposed model along with other conventional associative memory models, and the obtained patterns were related to the high-order or quasi-periodic points and the chaotic trajectories. In this paper, the structure of the Gaussian associative memory and its reduced models are introduced as well as the results of the bifurcation analysis are presented. Furthermore, the output sequences obtained from simulation of the recalling process are presented. We discuss the mechanism and the characteristics of the Gaussian associative memory based on the results of the analysis and the simulations conducted.

Time-Frequency and Nonlinear Analysis of Tidal Data Observed on the Kuroshio Path

The tidal data of Kushimoto and Uragami on flow path of Kuroshio from 2004 to 2005 are investigated and discussed by time-frequency methods and nonlinear methods in this paper. These analyzing methods based on mathematical science show us new findings about the tidal motion observed on Kuroshio flow path. On the time-frequency analysis, 12 hours component and 24 hours component swing during the period of 350 hours and 320 hours respectively. However, any remarkable differences or changes depending on Kuroshio flow path weren’t seen on the result of time-frequency analysis. On the nonlinear analysis, a periodical structure has seen on the mutual information of tidal difference data, while Kuroshio flow is stable. In addition, the mutual information showed a characteristic of randomness and irregularity, while Kuroshio flow is unstable. The important results brought us a new finding such as classification of tidal motion regardless of the flow path of Kuroshio.

从实验室到市场:光声成像的产业化进程（英文）

Photoacoustic imaging(PAI) or optoacoustic imaging, the modern application of an ancient physical discovery to biomedical imaging, is without doubt one of the most exciting imaging technologies that has drawn increasing attention from biomedical specialists. In PAI, the rich contrast of optical excitation is seamlessly combined with the high spatial resolution and large penetration depth of ultrasonic detection to produce clear images of optically scattering biological tissues. As a complementary imaging modality that surpasses the territory of traditional microscopic optical imaging, PAI has been explored for numerous biomedical studies, and hence enthusiastically embraced by researchers around the globe who have attested to its unique imaging capabilities, namely the deep penetration and functional sensitivity.Not surprisingly, as the market clearly sees the promise, the commercial production of PAI systems has grown apace with the technological advancements and clinical applications. The adoption of commercial PAI in research and clinical settings has however seen difficulties, majorly due to costs, regulatory blocks,and competition with mainstream technologies. Here, from a practical standpoint, a wide range of commercial PAI systems currently available in the market were introduced, their advantages and disadvantages were analyzed, and the design considerations for targeted applications were emphasized. The key technological, logistical, and clinical issues were also discussed that need to be solved to accelerate the technology translations. By doing so, it is hoped that a clearer picture of the future commercialization of PAI for clinicians, researchers, and industrial entrepreneurs will be presented.

DC Motor Speed Regulator via Active Damping Injection and Angular Acceleration Estimation Techniques

This paper suggests a novel model-based nonlinear DC motor speed regulator without the use of a current sensor.The current dynamics,machine parameters and mismatched load variations are considered.The proposed controller is designed to include an active damping term that regulates the motor speed in accordance with the first-order low-pass filter dynamics through the pole-zero cancellation.Meanwhile,the angular acceleration and its reference are obtained from simple first-order estimators using only the speed information.The effectiveness is experimentally verified using hardware comprising the QUBEServo2,myRIO-1900,and LabVIEW.

An Algorithm for the Feedback Vertex Set Problem on a Normal Helly Circular-Arc Graph

The feedback vertex set (FVS) problem is to find the set of vertices of minimum cardinality whose removal renders the graph acyclic. The FVS problem has applications in several areas such as combinatorial circuit design, synchronous systems, computer systems, and very-large-scale integration (VLSI) circuits. The FVS problem is known to be NP-hard for simple graphs, but polynomi-al-time algorithms have been found for special classes of graphs. The intersection graph of a collection of arcs on a circle is called a circular-arc graph. A normal Helly circular-arc graph is a proper subclass of the set of circular-arc graphs. In this paper, we present an algorithm that takes time to solve the FVS problem in a normal Helly circular-arc graph with n vertices and m edges.

Discrete-Time Dynamic Image Segmentation Using Oscillators with Adaptive Coupling

In this study, we propose a novel discrete-time coupled model to generate oscillatory responses via periodic points with a high periodic order. Our coupled system comprises one-dimensional oscillators based on the Rulkov map and a single globally coupled oscillator. Because the waveform of a one-dimensional oscillator has sharply defined peaks, the coupled system can be applied to dynamic image segmentation. Our proposed system iteratively transforms the coupling of each oscillator based on an input value that corresponds to the pixel value of an input image. This approach enables our system to segment image regions in which pixel values gradually change with respect to a connected region. We conducted a bifurcation analysis of a single oscillator and a three-coupled model. Through simulations, we demonstrated that our system works well for gray-level images with three isolated image regions.

Investigation of cell mechanics using single-beam acoustic tweezers as a versatile tool for the diagnosis and treatment of highly invasive breast cancer cell lines: an in vitro study

Advancements in diagnostic systems for metastatic cancer over the last few decades have played a significant role in providing patients with effective treatment by evaluating the characteristics of cancer cells.Despite the progress made in cancer prognosis,we still rely on the visual analysis of tissues or cells from histopathologists,where the subjectivity of traditional manual interpretation persists.This paper presents the development of a dual diagnosis and treatment tool using an in vitro acoustic tweezers platform with a 50MHz ultrasonic transducer for label-free trapping and bursting of human breast cancer cells.For cancer cell detection and classification,the mechanical properties of a single cancer cell were quantified by single-beam acoustic tweezers(SBAT),a noncontact assessment tool using a focused acoustic beam.Cell-mimicking phantoms and agarose hydrogel spheres(AHSs)served to standardize the biomechanical characteristics of the cells.Based on the analytical comparison of deformability levels between the cells and the AHSs,the mechanical properties of the cells could be indirectly measured by interpolating the Young’s moduli of the AHSs.As a result,the calculated Young’s moduli,i.e.,1.527kPa for MDA-MB-231(highly invasive breast cancer cells),2.650kPa for MCF-7(weakly invasive breast cancer cells),and 2.772 kPa for SKBR-3(weakly invasive breast cancer cells),indicate that highly invasive cancer cells exhibited a lower Young’s moduli than weakly invasive cells,which indicates a higher deformability of highly invasive cancer cells,leading to a higher metastasis rate.Single-cell treatment may also be carried out by bursting a highly invasive cell with high-intensity,focused ultrasound.

Toward in vivo translation of superresolution localization photoacoustic computed tomography using liquid-state dyed droplets

Super-resolution localization photoacoustic computed tomography has been successfully performed in live animals using an injection of unprecedentedly absorptive liquid-state dyed droplets,which promises a disruptive modality for in vivo neuroimaging.

Ultrasensitive detection of Ebola matrix protein in a memristor mode

We demonstrate the direct biosensing of the Ebola VP40 matrix protein, using a memristor mode of a liquid-integrated nanodevice, based on a large array of honeycomb-shaped silicon nanowires. To shed more light on the principle of biodetection using memristors, we engineered the opening of the current-minima voltage gap VG by involving the third gap-control electrode （gate voltage, VG） into the system. The primary role of VG is to mimic the presence of the charged species of the desired sign at the active area of the sensor. We further showed the advantages of biodetection with an initially opened controlled gap （Vc~ ~a 0）, which allows the detection of the lowest concentrations of the biomolecules carrying arbitrary positive or negative charges; this feature was not present in previous configurations. We compared the bio-memristor performance, in terms of its detection range and sensitivity, to that of the already-known field-effect transistor （FET） mode by operating the same device. To our knowledge, this is the first demonstration of Ebola matrix protein detection using a nanoscaled electrical sensor.

Super-resolution localization photoacoustic microscopy using intrinsic red blood cells as contrast absorbers

Photoacoustic microscopy(PAM)has become a premier microscopy tool that can provide the anatomical,functional,and molecular information of animals and humans in vivo.However,conventional PAM systems suffer from limited temporal and/or spatial resolution.Here,we present a fast PAM system and an agent-free localization method based on a stable and commercial galvanometer scanner with a custom-made scanning mirror(L-PAM-GS).This novel hardware implementation enhances the temporal resolution significantly while maintaining a high signal-to-noise ratio(SNR).These improvements allow us to photoacoustically and noninvasively observe the microvasculatures of small animals and humans in vivo.Furthermore,the functional hemodynamics,namely,the blood flow rate in the microvasculature,is successfully monitored and quantified in vivo.More importantly,thanks to the high SNR and fast B-mode rate(500 Hz),by localizing photoacoustic signals from captured red blood cells without any contrast agent,unresolved microvessels are clearly distinguished,and the spatial resolution is improved by a factor of 2.5 in vivo.LPAM-GS has great potential in various fields,such as neurology,oncology,and pathology.

Beyond the acoustic diffraction limit: superresolution localization optoacoustic tomography (LOT)

Localization optoacoustic tomography provides superresolution imaging capability in 3D beyond the acoustic diffraction limit,which can be crucial for mapping microcirculation in cancers,brain functions,peripheral vascular diseases,etc.Optoacoustic(also referred to as photoacoustic)tomography(OAT)has been gaining popularity for preclinical and clinical imaging during the past couple of decades1.OAT breaks the long-standing shallow imaging depth limitation of conventional optical imaging by forming an image using the optoacoustic(OA)effect.Through advances in ultrasound imaging technologies,OAT provides rich optical contrast while achieving high spatial resolution deep inside living subjects(up to several centimeters).Thanks to these hybrid technologies,the use of preclinical OAT to study cancer physiopathology,neural physiology,drug delivery,vascular diseases,etc.,has spread globally to many laboratories.More importantly,the applications of OAT have been extended to include many clinical trials,such as early diagnosis and treatment monitoring of cancers,imaging of the bowel for diseases,human neuroimaging for diagnosing neurological defects,imaging of peripheral arteries and veins for detecting vascular disease,and intravascular imaging for characterizing plaque.

Fluoropolymer-based organic memristor with multifunctionality for flexible neural network system

In this study,we propose an effective strategy for achieving the flexible one organic transistor–one organic memristor(1T–1R)synapse using the multifunctional organic memristor.The dynamics of the conductive nanofilament(CF)in a hydrophobic fluoropolymer medium is explored and a hydrophobic fluoropolymer-based organic memristor is developed.The flexible 1T–1R synapse can be fabricated using the solution process because the hydrophobic fluorinated polymer layer is produced on the organic transistor without degradation of the underlying semiconductor.The developed flexible synapse exhibits multilevel conductance with high reliability and stability because of the fluoropolymer film,which acts as a medium for CF growth and an encapsulating layer for the organic transistor.Moreover,the synapse cell shows potential for high-density memory systems and practical neural networks.This effective concept for developing practical flexible neural networks would be a basic platform to realize the smart wearable electronics.

Super-resolution visible photoactivated atomic force microscopy

Imaging the intrinsic optical absorption properties of nanomaterials with optical microscopy(OM)is hindered by the optical diffraction limit and intrinsically poor sensitivity.Thus,expensive and destructive electron microscopy(EM)has been commonly used to examine the morphologies of nanostructures.Further,while nanoscale fluorescence OM has become crucial for investigating the morphologies and functions of intracellular specimens,this modality is not suitable for imaging optical absorption and requires the use of possibly undesirable exogenous fluorescent molecules for biological samples.Here we demonstrate super-resolution visible photoactivated atomic force microscopy(pAFM),which can sense intrinsic optical absorption with~8 nm resolution.Thus,the resolution can be improved down to~8 nm.This system can detect not only the first harmonic response,but also the higher harmonic response using the nonlinear effect.The thermoelastic effects induced by pulsed laser irradiation allow us to obtain visible pAFM images of single gold nanospheres,various nanowires,and biological cells,all with nanoscale resolution.Unlike expensive EM,the visible pAFM system can be simply implemented by adding an optical excitation sub-system to a commercial atomic force microscope.