High Spacial Resolution Research Articles

Experimental analysis of water-droplet–fiber interaction on a mechanically excited hydrophobic fiber

In this study, the dynamics of a single water droplet on a mechanically excited single fiber are investigated fundamentally. By utilizing state-of-the-art high-speed camera technology, the droplet's motion is captured with exceptional temporal resolution, enabling a detailed analysis of its position, size, and kinetics. We can identify distinct motion patterns of a droplet adhering to the fiber, which can exhibit either a static, a tilting, or swinging motion. The swinging and tilting motion can be overlaid with a higher-frequency deformation in response to the fiber excitation. Additionally, we examine the detachment of the droplet from the fiber as well as for the first time the (periodic) reattachment resulting from the mechanical excitation. The used droplet volumes are smaller, and the excitation shown here is greater than the excitation acceleration previously investigated in single fiber studies. Insights into droplet–fiber interactions can provide a better understanding of the mechanisms occurring in coalescence filters in harsh environments, which cannot be observed in situ with high temporal and spacial resolution in a full-scale filter due to the lack of optical access.

An Optimal Control Method for Greenhouse Climate Management Considering Crop Growth’s Spatial Distribution and Energy Consumption

The environmental factors of greenhouses affect crop growth greatly and are mutually coupled and spatially distributed. Due to the complexity of greenhouse climate modeling, the current optimal control of greenhouse crop growth rarely considers the spatial distribution issues of environmental parameters. Proper Orthogonal Decomposition (POD) is a technique to reduce the order of a model by projecting it onto an orthogonal basis. In this paper, POD is used to extract environmental features from Computational Fluid Dynamics (CFD) simulations, and a low-dimensional feature subspace is obtained by energy truncation. With multi-dimensional interpolation, fast and low-dimensional reconstruction of the dynamic variation of greenhouse climates is achieved. On this basis, a rolling-horizon optimal control scheme is proposed. For each finite horizon, the external meteorological data are updated, and the response of the greenhouse environment is quickly calculated by the POD model. With the performance criterion J of maximizing crop production and energy efficiency, through the particle swarm optimization algorithm, the optimal settings for the greenhouse shading rate and the fan speed are derived. Such control computations are rolled forward during the whole planting season. Results of a case study show that the proposed method has low computation cost and high spacial resolution and can effectively improve the spatiotemporal accuracy of greenhouse climate management. In addition, different from traditional global optimal control methods, the proposed rolling-horizon scheme can correct various external disturbances in the procedure of crop growth, and thus it is more robust and has potential for engineering applications.

Multi Surface Electrodes Nerve Bundles Stimulation on the Wrist: Modified Location of Tactile Sensation on the Palm

Transcutaneous electrical nerve stimulation (TENS) of nerve bundles, such as ulnar and median nerves, is a technique used to evoke tactile sensation on the hand. Considering this technique does not require electrodes to be attached to the hand, it can induce sensation without interrupting the interaction between the hand and environment. Although this technology has most commonly been explored for restoring sensory feedback in amputees, it can also be applied to tactile devices for able-bodied individuals to solve problems that recent tactile interfaces have been facing such as interference of the device with the interaction between the hand and environment. We propose TENS at the wrist with multi-electrode targeting the cutaneous nerve bundles as a method to induce tactile sensation with higher spacial resolution, and without unintended tactile sensation at the upper arm. In this study, we demonstrated through psychophysical experiments and finite element simulation that our method induces sensation only at the hand, and that it could control the location of induced tactile sensation in the circumference direction.

PolSAR Models with Multimodal Intensities

Polarimetric synthetic aperture radar (PolSAR) systems are an important remote sensing tool. Such systems can provide high spacial resolution images, but they are contaminated by an interference pattern called multidimensional speckle. This fact requires that PolSAR images receive specialised treatment; particularly, tailored models which are close to PolSAR physical formation are sought. In this paper, we propose two new matrix models which arise from applying the stochastic summation approach to PolSAR, called compound truncated Poisson complex Wishart (CTPCW) and compound geometric complex Wishart (CGCW) distributions. These models offer the unique ability to express multimodal data. Some of their mathematical properties are derived and discussed—characteristic function and Mellin-kind log-cumulants (MLCs). Moreover, maximum likelihood (ML) estimation procedures via expectation maximisation algorithm for CTPCW and CGCW parameters are furnished as well as MLC-based goodness-of-fit graphical tools. Monte Carlo experiment results indicate ML estimates perform at what is asymptotically expected (small bias and mean square error) even for small sample sizes. Finally, our proposals are employed to describe actual PolSAR images, presenting evidence that they can outperform other well-known distributions, such as WmC, Gm0, and Km.

Comparative Accuracy Study Of LDV Profile-Sensor Acquisition Modes And Particle Diameters

The laser Doppler velocity profile sensor (LDV-PS) system offers the possibility to measure flow velocities with high spatial resolution and is therefore a promising method for the investigation of flows with high velocity gradients. The present experimental study revolves around the interplay between a broad range of chosen LDV-PS acquisition parameters, the dynamic velocity range within the observed measurement volume, and the accuracy of the velocity and position estimation from an application perspective. In the chosen set-up, thin wires of different diameters rotate at varying velocity levels and are captured instead of tracer particles by the applied system. It is observed that constant sample rate and number for the Fast Fourier Transform (FFT) evaluation of the detected burst signal allow straightforward measurements of unknown velocity profiles, but imply a velocity-dependent spatial measurement uncertainty. In contrast, velocity-adjusted acquisition settings allow to acquire particle bursts with equal signal resolution and length effecting a constant measurement accuracy at all velocity levels when adjusted appropriately. The position standard deviation is furthermore observed to increase with the wire diameter.Hence, the size of the scattering object should be chosen appropriately small during calibration and measurement. The gained knowledge offers the possibility to adapt the evaluation parameters more specifically to a given measurement problem.Consequently, measurements can be conducted in flows with small velocities with a high spacial resolution, when the FFT parameters and processing routines are adjusted accordingly, small particles are chosen and vibrations in the set-up are avoided.

Activation mechanism of human soluble guanylate cyclase by stimulators and activators

Soluble guanylate cyclase (sGC) is the receptor for nitric oxide (NO) in human. It is an important validated drug target for cardiovascular diseases. sGC can be pharmacologically activated by stimulators and activators. However, the detailed structural mechanisms, through which sGC is recognized and positively modulated by these drugs at high spacial resolution, are poorly understood. Here, we present cryo-electron microscopy structures of human sGC in complex with NO and sGC stimulators, YC-1 and riociguat, and also in complex with the activator cinaciguat. These structures uncover the molecular details of how stimulators interact with residues from both β H-NOX and CC domains, to stabilize sGC in the extended active conformation. In contrast, cinaciguat occupies the haem pocket in the β H-NOX domain and sGC shows both inactive and active conformations. These structures suggest a converged mechanism of sGC activation by pharmacological compounds.

Picometer scale electron microscopy exploration for the functionality origin of functional materials

The functionality of functional materials originates from field and local symmetry. The local symmetry in matter science is described by four degrees of freedom: Lattice, charge, orbit and spin. To understand and use the rich physical properties brought by the structural distortion of atomic nearest neighbors and second nearest neighbors under symmetry breaking, we need to grasp the fine structure of matter at the picometer scale. This paper reviews the exploration of the origin of functional materials by picometer scale electron microscopy in the three cases in the lattice degree of freedom, the expansion and contraction of the polyhedron, the tilt and rotation of the polyhedron and the cation displacement. In the expansion and contraction of the polyhedron degree of freedom, we use picometer scale scanning transmission electron microscopy (STEM) studies of lithium ion battery materials, which can be classified as the unit cell breathing model and Jahn-Teller effect, to illustrate the relationship between functionalities and structural origins. In the tilt and rotation of the polyhedron degree of freedom, we mainly focus on the heterointerface among functional oxides. The emergent phenomena arising from this heterointerface form most of the topics of modern condensed matter physics, such as high temperature superconductivity, magnetoresistance, antiferromagnetic, multiferroics, etc. Lattice mismatch caused polyhedron tilt and rotation alter the local symmetry of the oxides, and hence various functionalities are created. In terms of cation displacement degree of freedom, ferroelectricity is the typical example to show the structure-property relationship. The most exciting future of ferroelectric material is the potential to be the next generation memory material because of its topological property. With the help of aberration corrected (AC)-STEM, flux closure type and vortex type ferroelectric domain were directly observed at picometer accuracy. Furthermore, through in-situ mechanical and electric force studies, reverse transition from topological and normal ferroelectric state was observed, which paves the way of the application of the ferroelectric material as future memory material system. At the electronic structure level, the charge structure under the picometer-scale lattice structure is reviewed. Through the simultaneously recorded EELS data, we can know the valence state and content fluctuation of certain element. For example, in lithium ion battery materials, atomic and electronic structure changes all the time during the whole working duration. It is crucial to know the local valence state of the transition metal elements. AC-STEM and electron energy loss spectroscopy (EELS) can help us to solve this problem under one time acquisition. And future perspectives of the electron microscopy research on the orbit and spin structure with high spacial resolution are discussed, such as monochromatic EELS, electron-energy-loss magnetic circular dichroism (EMCD), electron-energy-loss magnetic linear dichroism (EMLD) and convergent beam electron diffraction (CBED). CBED is considered to be the best way to discover the orbit structure with high spacial resolution. In terms of spin structure, EMCD and EMLD are not the direct methods to detect the electron spin, which limits the resolution and signal to noise ratio of acquired results. In the future, spin polarized electron source is considered as the proper way to discover the spin structure with high spacial resolution. Nowadays, spacial resolution is not the limit of the TEM. The ability of accessing more kinds of materials, powerful in-situ method and acquiring orbit and spin structure with picometer resolution are goals for us.

Turning on two-photon activity over N∧N∧N cyclometalated Pt(II) complex by introducing flexible chains

The rational design and fabrication of two-photon excited fluorescent probes for noninvasive bioimaging with deeper tissue penetration and higher spacial resolution is a high-priority target yet grand challenge. To this end, herein, a novel amphiphilic N∧N∧N cyclometalated Pt(II) complex (Pt–N1) was designed and synthesized. Benefiting from its flexible chains and abundant electronic structure, it displayed excellent aggregation-induced emission (AIE) behavior under physiological conditions due to its self-assembly process with the proportion of water increased. As a result, Pt–N1 exhibited considerable two-photon action cross-section in aggregation state, suggesting its potential application in bioimaging.

A Wearable Vision-To-Audio Sensory Substitution Device for Blind Assistance and the Correlated Neural Substrates

There are a very few people who have the ability to “see” the surroundings by the echoes, which is called echolocation. The study of the brain mechanism of echolocation can not only help to improve the blind assistance device, but also provides a window into the research of brain’s plasticity. In this paper, we developed a wearable system to transform the spatial information captured by camera into a voice description and fed it back to blind users which is inspired by echolocation. After our online virtual scene training, users can easily discriminate object location in the camera’s view, motion of the objects, even shape of the objects. Compared with natural echolocation, it’s easier to learn and be applied in daily life. In addition, the device achieves high spacial resolution. In this study, two trained blind subjects and two non-trained sighted subjects were tested by using functional Magnetic Resonance Imaging (fMRI). We obtain the fMRI images of the subjects’ brain activity when they were listening to the sound of the wearable prototype. Intriguingly, we find that after training with the blind assistance system, the blind’ visual area of the brain have been activated when they are dealing with the acoustic feedback from the device.

Subject specific hand and forearm musculoskeletal 3D geometries using high-resolution MR images

Magnetic medical imaging (MRI) is commonly used to 3D rendering of musculoskeletal structures. However, due to technical limitations of the device e.g. the coil, high-spacial resolution is available only for a small field of view. However in the case of hand and forearm investigation, and due to the long tendon and small bones, both high special and a large field of view are required. It is the aim of this study to propose the in silico enlargement of the field of view to 3D visualise all hand’s bones and tendons paths. Using MRI clinical routine sequence, we detailed a procedure of hand immobilisation by alginate and registration of up to four consecutive MRI volume acquisitions. In order to validate our method, we evaluated the accuracy of the anatomical structures segmentation (i), the robustness of the registration by a sensitivity analysis (ii) and the accuracy of the 3D reconstruction by comparison with computer tomography imaging (iii). The results demonstrated a mean error of 1 mm on the 3D external surface and of 0.94 mm on the localisation of the hand bones. We also tested different hand sizes and showed that the field of view could be increased up to 2.3 time compared to the original one.

Thermal decomposition of fullerene nanowhiskers protected by amorphous carbon mask.

Fullerene nanostructures are well known for their unique morphology, physical and mechanical properties. The thermal stability of fullerene nanostructures, such as their sublimation at high temperature is also very important for studying their structures and applications. In this work, We observed fullerene nanowhiskers (FNWs) in situ with scanning helium ion microscopy (HIM) at elevated temperatures. The FNWs exhibited different stabilities with different thermal histories during the observation. The pristine FNWs were decomposed at the temperatures higher than 300 °C in a vacuum environment. Other FNWs were protected from decomposition with an amorphous carbon (aC) film deposited on the surface. Based on high spacial resolution, aC film with periodic structure was deposited by helium ion beam induced deposition (IBID) on the surface of FNWs. Annealed at the high temperature, the fullerene molecules were selectively sublimated from the FNWs. The periodic structure was formed on the surface of FNWs and observed by HIM. Monte Carlo simulation and Raman characterization proved that the morphology of the FNWs was changed by helium IBID at high temperature. This work provides a new method of fabricating artificial structure on the surface of FNWs with periodic aC film as a mask.

Nanoscale nonlinear effects in Erbium-implanted Yttrium Orthosilicate

Doping of substrates at desired locations is a key technology for spin-based quantum memory devices. Focused ion beam implantation is well-suited for this task due to its high spacial resolution. In this work, we investigate ion-beam implanted Erbium ensembles in Yttrium Orthosilicate crystals by means of confocal photoluminescence spectroscopy. The sample temperature and the post-implantation annealing step strongly reverberate in the properties of the implanted ions. We find that hot implantation leads to a higher activation rate of the ions. At high enough fluences, the relation between the fluence and final concentration of ions becomes non-linear. Two models are developed explaining the observed behavior.

Large areas elemental mapping by ion beam analysis techniques

The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

Spacial Resolution Enhancement for Integrated Magnetic Probe by Two-Step Removal of Si-Substrate Beneath the Coil

This paper presents an enhancement of high spacial resolution magnetic probe for the applications of measuring magnetic fields emitted from cryptography micro-electronic devices. The on-chip sensing system includes a magnetic pick-up coil, three-stage low-noise amplifier, mixer, and low-pass filter. Noise problems are reduced by the proposal of using the down-conversion mixer. A two-step removal of Si-substrate (Si-SUBS) areas is also proposed by applying a focused-ion-beam process to avoid eddy currents that reduces the coil sensitivity. Four probe chips are fabricated in a 0.18 um CMOS five-metal layer process with different coil sizes and with/without Si-SUBS removals. Experimental results on a thin wire and micro-strip line show the proposed system achieves high spacial resolution and sensitivity for near-field magnetic scanning.

Development of High Sensitivity Nuclear Emulsion and Fine Grained Emulsion

Nuclear emulsion is a particle detector having high spacial resolution and angular resolution. It became useful for large statistics experiment thanks to the development of automatic scanning system. In 2010, a facility for emulsion production was introduced and R&D of nuclear emulsion began at Nagoya university. In this paper, we present results of development of the high sensitivity emulsion and fine grained emulsion for dark matter search experiment. Improvement of sensitivity is achieved by raising density of silver halide crystals and doping well-adjusted amount of chemicals. Production of fine grained emulsion was difficult because of unexpected crystal condensation. By mixing polyvinyl alcohol (PVA) to gelatin as a binder, we succeeded in making a stable fine grained emulsion.

Experimental investigation of supersonic flow over elliptic surface

Abstract The coherent structures of flow over a compression elliptic surface are experimentally investigated in a supersonic low-noise wind tunnel at Mach Number 3 using nano-tracer planar laser scattering (NPLS) and particle image velocimetry (PIV) techniques. High spacial resolution images and the average velocity profiles of both laminar inflow and turbulent inflow over the testing model were captured. From statistically significant ensembles, spatial correlation analysis of both cases is performed to quantify the mean size and orientation of large structures. The results indicate that the mean structure is elliptical in shape and structure angles in separated region of laminar inflow are slightly smaller than that of turbulent inflow. Moreover, the structure angle of both cases increases with its distance away from from the wall. POD analysis of velocity and vorticity fields is performed for both cases. The energy portion of the first mode for the velocity data is much larger than that for the vorticity field. For vorticity decompositions, the contribution from the first mode for the laminar inflow is slightly larger than that for the turbulent inflow and the cumulative contributions for laminar inflow converges slightly faster than that for turbulent inflow

THERMAL AND DYNAMICAL PROPERTIES OF GAS ACCRETING ONTO A SUPERMASSIVE BLACK HOLE IN AN ACTIVE GALACTIC NUCLEUS

(Abridged) We study stability of gas accretion in Active Galactic Nuclei. Our grid based simulations cover a radial range from 0.1 to 200 pc. Here, as in previous studies by our group, we include gas radiative cooling as well as heating by a sub-Eddington X-ray source near the central supermassive black hole of 10^8 M_{\odot}. Our theoretical estimates and simulations show that for the X-ray luminosity L_X \sim 0.008 L_{Edd}, the gas is thermally and convectivelly unstable within the computational domain. In the simulations, we observe that very tiny fluctuations in an initially smooth, spherically symmetric, accretion flow, grow first linearly and then non-linearly. Consequently, an initially one-phase flow relatively quickly transitions into a two-phase/cold-hot accretion flow. For L_X = 0.015 L_{Edd} or higher, the cold clouds continue to accrete but in some regions of the hot phase, the gas starts to move outward. For L_X < 0.015 L_{Edd}, the cold phase contribution to the total mass accretion rate only moderately dominates over the hot phase contribution. This result might have some consequences for cosmological simulations of the so-called AGN feedback problem. Our simulations confirm the previous results of Barai et al. (2012) who used smoothed particle hydrodynamic simulations to tackle the same problem. However here, because we use a grid based code to solve equations in 1-D and 2-D, we are able to follow the gas dynamics at much higher spacial resolution and for longer time in comparison to the 3-D SPH simulations. One of new features revealed by our simulations is that the cold condensations in the accretion flow initially form long filaments, but at the later times, those filaments may break into smaller clouds advected outwards within the hot outflow. These simulations may serve as an attractive model for the so-called Narrow Line Region in AGN.

CARS diagnostics of near-critical fluid in small mesopores

Due to the high spacial resolution and theinterference nature, coherent anti-Stokes Ramanscattering (CARS) spectroscopy is well suited forthe diagnostics of composites based on transparentnanoporous hosts. In particular, the adsorption of afluid on the walls of nanopores and the formation ofa condensed phase in their volume leads to obvioustransformation of the CARS spectra. Recently wehave developed a model which describes thebehavior of molecular spectra at isothermalcompression in cylindrical nanopores. Calculationsbased on the model have shown a good agreementwith the experimental results for carbon dioxide innanoporous glass with pores of diameter of severalnanometers. Here we use the developed approach toinvestigate the phase behavior of carbon dioxide inglass nanopores at near-critical temperatures. It hasbeen experimentally shown that condensation innanopores occurs at relatively low pressures atsubcritical and even at supercritical temperatures.The analysis based on the developed model allowsto reveal some qualitative and quantitativecharacterizations of the shift of critical point.

Phase Transformation Related Conductivity Degradation of NiO Doped YSZ: AnIn-situMicro-Raman Analysis

ABSTRACTIn-situ micro Raman spectroscopy has been adopted as one of the most powerful analytical techniques with high spacial resolution under controlled atmospheres. In the present study, phase transformation of NiO doped yttria stabilized zirconia (YSZ) was monitored by in-situ micro-Raman spectroscopy. Raman spectra change caused by the phase transformation from the cubic phase to the tetragonal phase was observed for the NiO doped YSZ during annealing at a high temperature of 1173 K under reducing atmosphere.

Particle temperature measurement using pair distribution function in complex plasmas

In order to obtain more reliable particle temperature of complex plasmas, a new method of obtaining it in a solid phase is investigated. Since a conventional method uses a velocity distribution function (VDF), both high spacial resolution and sufficiently large observation area are required for sufficient measurement accuracy. It is often difficult, however, to satisfy them simultaneously due to necessities of highly magnified observation for the former requirement and low magnified one for the latter one. Therefore, we investigate another method of estimating particle temperature in the solid phase by use of a pair distribution function (PDF). This method has a feature that only one observation magnification is required. From comparison between the experimentally obtained PDF's and calculated ones, mean square displacement (MSD) is determined. The temperature is estimated by using the MSD if the particle motion is regarded as harmonic oscillation. It is found that the obtained temperature from the PDF is consistent with that from the VDF.