Spatial Resolution Mode Research Articles

Soft wearable electronics for evaluation of biological tissue mechanics

Flexible wearable devices designed to evaluate the biomechanical properties of deep tissues not only facilitate continuous and effective monitoring in basic performance but also exhibit significant potential in broader disease assessments. Recent advancements are highlighted in the structural and principled design of platforms capable of capturing various biomechanical signals. These advancements have led to enhanced testing capabilities concerning spatial scales and resolution modes at different depths. This review discusses the engineering of soft wearable devices for the biomechanical evaluation of deep tissue signals. It encompasses different measurement modes, device design and fabrication methods, integrated circuit (IC) integration schemes, and the characteristics of measurement depth and accuracy. The core discussion focuses on platform development, targeting different monitoring sites and platform structure design, ranging from linear strain gauges and conformal stretchable sensors to complex three-dimensional (3D) circuit-integrated stretchable arrays. We further explore various technologies associated with different measurement mechanisms and engineering designs, as well as the penetration depth and spatial resolution of these wearable sensors. The practical applications of these technologies are evident in the monitoring of deep tissue signals and changes in tissue characteristics. The results suggest that wearable biomechanical sensing systems hold substantial promise for applications in healthcare and research.

Development of a dual-mode energy-resolved neutron imaging detector: High spatial resolution and large field of view

Energy-resolved neutron imaging is an effective way to investigate the internal structure and residual stress of materials. Different sample sizes have varying requirements for the detector's imaging field of view (FOV) and spatial resolution. Therefore, a dual-mode energy-resolved neutron imaging detector was developed, which mainly consisted of a neutron scintillator screen, a mirror, imaging lenses, and a time-stamping optical fast camera. This detector could operate in a large FOV mode or a high spatial resolution mode. To evaluate the performance of the detector, the neutron wavelength spectra and the multiple spatial resolution tests were conducted at CSNS. The results demonstrated that the detector accurately measured the neutron wavelength spectra selected by a bandwidth chopper. The best spatial resolution was about 20 μm in high spatial resolution mode after event reconstruction, and a FOV of 45.0 mm × 45.0 mm was obtained in large FOV mode. The feasibility was validated to change the spatial resolution and FOV by replacing the scintillator screen and adjusting the lens magnification.

Panoramic chemical imaging of opium alkaloids in Papaver somniferum by TOF-SIMS

Accurate mapping of opium alkaloids in Papaver somniferum (P. somniferum) is significant for comprehensively elucidating their biosynthetic pathways and metabolic regulations. Here we describe a panoramic chemical imaging strategy based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) that enables a thorough and precise visualization of the spatial differentiation of five opium alkaloids (morphine, codeine, thebaine, papaverine and noscapine) in P. somniferum. Notably, the opium alkaloids exhibited enrichment in the capsule, pistil, receptacle and peduncle. Moreover, a series of cross sections of a capsule were imaged to reveal a three-dimensional horizon of internal distribution of opium alkaloids. Opium alkaloids were observed enriched within the pseudoseptum and the “tube-like” structure of the inner pod wall, witnessing a downward trend toward the stigmatic disk. Finally, in high spatial resolution mode of TOF-SIMS, direct single-cell level chemical mapping of opium alkaloids in the phloem of the vascular bundles of P. somniferum receptacle was achieved for the first time. The introduced imaging strategy can provide multi-dimensional insights into the spatial distribution of opium alkaloids in P. somniferum, and the findings are expected to facilitate shedding light on the biological activities of these pharmacologically valued alkaloids.

Efficient calculation of k -integrated electron energy loss spectra: Application to monolayers of MoS2, hBN, and graphene

The theoretical scattering cross section of electron energy loss spectroscopy (EELS) is essentially given by $\ensuremath{-}\text{Im}\phantom{\rule{0.16em}{0ex}}{\ensuremath{\varepsilon}}^{\ensuremath{-}1}(\mathbf{k},\ensuremath{\omega})$ with the energy loss $\ensuremath{\hbar}\ensuremath{\omega}$ and the momentum transfer $\ensuremath{\hbar}\mathbf{k}$. The macroscopic dielectric function $\ensuremath{\varepsilon}(\mathbf{k},\ensuremath{\omega})$ can be calculated from first principles using time-dependent density-functional theory. However, experimental EELS measurements have a finite $\mathbf{k}$ resolution or, when operated in spatial resolution mode, yield a $\mathbf{k}$-integrated loss spectrum, which deviates significantly from EEL spectra calculated for specific $\mathbf{k}$ momenta. On the other hand, integrating the theoretical spectra over $\mathbf{k}$ is complicated by the fact that the integrand varies over several (typically six) orders of magnitude around $k=0$. In this article, we present a stable technique for integrating EEL spectra over an adjustable range of momentum transfers. The important region around $k=0$, where the integrand is nearly divergent, is treated partially analytically, allowing an analytic integration of the near divergence. The scheme is applied to three prototypical two-dimensional systems: monolayers of ${\mathrm{MoS}}_{2}$ (semiconductor), hexagonal BN (insulator), and graphene (semimetal). Here, we are confronted with the added difficulty that the long-range Coulomb interaction leads to a very slow supercell (vacuum size) convergence. We address this difficulty by employing an extrapolation scheme, enabling an efficient reduction of the supercell size and thus a considerable speedup in computation time. The calculated $\mathbf{k}$-integrated spectra are in very favorable agreement with experimental EEL spectra.

Full‐field out‐of‐plane vibration displacement acquisition based on speckle‐projection digital image correlation and its application in damage localization

AbstractStereo‐digital image correlation (Stereo‐DIC) has been widely explored for modal analysis in plate‐type structures due to its noncontact and full‐field advantages. However, when the traditional stereo‐DIC is adopted to capture the out‐of‐plane displacements, several challenging issues exist such as the development of surface speckles, asynchronous camera recording, and efficiency and accuracy degradation due to high computation costs. Moreover, with the captured out‐of‐plane displacements, effective and efficient evaluation of the high spatial resolution mode shapes and their application to damage localization are also critical problems. To tackle these issues, a speckle‐projection DIC technique using a single high‐speed camera is proposed to obtain the out‐of‐plane vibration displacements. Moreover, an enhanced peak‐picking modal analysis method is adopted to enhance the estimation accuracy and efficiency of mode shapes. In addition, the low‐rank property of mode shapes in an intact state and the spatial sparse property of damage locations are harnessed for the detection of damage positions without requiring reference data on the healthy state. Finally, the modal analysis and damage localization results based on the proposed speckle‐projection DIC are compared with those of the traditional two‐camera stereo‐DIC technique to verify its feasibility and effectiveness. It is found that the differences in the identified resonant frequencies between these two methods are smaller than 1% for higher modes. Moreover, the proposed speckle‐projection DIC has the same accuracy as the traditional two‐camera stereo‐DIC in terms of measurement accuracy, mode shape estimation, and damage localization.

Multiplex optical bioassays for food safety analysis: Toward on-site detection.

Food safety analysis plays a significant role in controlling food contamination and supervision. In recent years, multiplex optical bioassays (MOBAs) have been widely applied to analyze multiple hazards due to their efficiency and low cost. However, due to the challenges such as multiplexing capacity, poor sensitivity, and bulky instrumentation, the further application of traditional MOBAs in food screening has been limited. In this review, effective strategies regarding food safety MOBAs are summarized, such as spatial-resolution modes performed in multi-T lines/dots strips or arrays of strip/microplate/microfluidic chip/SPR chip and signal-resolution modes employing distinguishable colorimetric/luminescence/fluorescence/surface plasma resonance/surface-enhanced Raman spectrum as signal tags. Following this, new trends on how to design engineered sensor architecture and exploit distinguishable signal reporters, how to improve both multiplexing capacity and sensitivity, and how to integrate these formats into smartphones so as to be mobile are summarized systematically. Typically, in the case of enhancing multiplexing capacity and detection throughput, microfluidic array chips with multichannel architecture would be a favorable approach to overcome the spatial and physical limitations of immunochromatographic assay (ICA) test strips. Moreover, noble metal nanoparticles and single-excitation, multiple-emission luminescence nanomaterials hold great potential in developing ultrasensitive MOBAs. Finally, the exploitation of innovative multiplexing strategy hybridized with powerful and widely available smartphones opens new perspectives to MOBAs. In future, the MOBAs should be more sensitive, have higher multiplexing capacity, and easier instrumentation.

First direct dynamical detection of a dual supermassive black hole system at sub-kiloparsec separation

We investigated whether the two recently discovered nuclei in NGC 7727 both host a super-massive black hole (SMBH). We used the high spatial resolution mode of the integral-field spectrograph MUSE on the VLT in adaptive optics mode to resolve the stellar kinematics within the sphere of influence of both putative black holes. We combined the kinematic data with an HST-based mass model and used Jeans models to measure their SMBH mass. We report the discovery of a dual SMBH system in NGC 7727. We detect a SMBH in the photometric center of the galaxy in Nucleus 1, with a mass of MSMBH = 1.54−0.15+0.18 × 108 M⊙. In the second nucleus, which is 500 pc offset from the main nucleus, we also find a clear signal for a SMBH with a mass of MBH = 6.33−1.40+3.32 × 106 M⊙. Both SMBHs are detected at high significance. The off-axis nature of Nucleus 2 makes modeling the system challenging; however, a number of robustness tests suggest that a black hole is required to explain the observed kinematics. The SMBH in the offset Nucleus 2 makes up 3.0% of its total mass, which means its SMBH is over-massive compared to the MBH − MBulge scaling relation. This confirms it as the surviving nuclear star cluster of a galaxy that has merged with NGC 7727. This discovery is the first dynamically confirmed dual SMBH system with a projected separation of less than a kiloparsec and the nearest dynamically confirmed dual SMBH at a distance of 27.4 Mpc. The second Nucleus is in an advanced state of inspiral, and it will eventually result in a 1:24 mass ratio SMBH merger. Optical emission lines suggest Nucleus 2 is a Seyfert galaxy, making it a low-luminosity Active Galactic Nuclei. There are likely many more quiescent SMBHs as well as dual SMBH pairs in the local Universe that have been missed by surveys that focus on bright accretion signatures.

LDV-induced stroboscopic digital image correlation for high spatial resolution vibration measurement.

Vibration measurement, particularly mode shape measurement, is an important aspect of structural dynamic analysis since it can validate finite element or analytical vibration models. Scanning laser Doppler vibrometry (LDV) and high-speed digital image correlation have become dominant methods for experimental mode shape measurement. However, these methods have high equipment costs and several disadvantages regarding spatial or temporal performance. This paper proposes a laser Doppler vibrometer induced stroboscopic digital image correction for non-contact mode shape and operational deflection shape measurement. Our results verify that single-point LDV and normal rate cameras can be used obtain high spatial resolution mode shape and operational deflection shape. Measurement frequency range is much higher than the camera capturing rate. We also show that the proposed approach coincides well with time-averaged electronic speckle pattern interferometry.

Gravity Wave Observations by the Mars Science Laboratory REMS Pressure Sensor and Comparison With Mesoscale Atmospheric Modeling With MarsWRF

AbstractSurface pressure measurements on Mars have revealed a wide variety of atmospheric phenomena. The Mars Science Laboratory Rover Environmental Monitoring Station pressure sensor data set is now the longest duration record of surface pressure on Mars. We use the first 2580 Martian sols, nearly 4 Mars years, of measurements to identify atmospheric pressure waves with periods of tens of minutes to hours using wavelet analysis on residual pressure after the tidal harmonics are removed. We find these waves have a clear diurnal cycle with strongest activity in the early morning and late evening and a seasonal cycle with the strongest waves in the second half of the martian year (Ls = 180–360°). The strongest such waves of the entire mission occurred during the Mars Year 34 global dust storm. Comparable atmospheric waves are identified using atmospheric modeling with the MarsWRF general circulation model in a “nested” high spatial resolution mode. With the support of the modeling, we find these waves best fit the expected properties of inertia‐gravity waves with horizontal wavelengths of O(100s) of km.

Is order creation through disorder in additive manufacturing possible?

Additive manufacturing is based on a deterministic principle of spatially localized material transformation. By using spatial energy resolution modes, it is thus possible to produce an object that ...

Nonnegative matrix factorization-based blind source separation for full-field and high-resolution modal identification from video

Traditional modal analysis requires physically attached sensors for data acquisition and vibration-based monitoring. Although traditional modal analysis presents well-established techniques for dynamics analysis, they can impose mass-loading effects on lightweight structures and increase budgetary demands on the maintenance of such data acquisition systems. Recently video-based techniques have become of increasing interest in the identification of the dynamic properties of infrastructures with arbitrary complexity. However, most applications rely on frame by frame tracking of fixed speckle targets to derive time-varying physical parameters. This imposes serious limitations for real-world applications, especially in scenarios where the structure is out of reach. Therefore, to address these issues, we propose a novel output-only operational modal analysis method based on vision-based blind source separation scheme. The proposed algorithm makes use of each pixel as a potential measurement point. This enables an increase in the spatial density of sensors conventionally used on a structure by orders of magnitude. This simultaneous processing of all pixel time-series derives full-field high-resolution mode shapes instead of low spatial resolution mode shapes achieved when measuring a limited number of discrete locations with typical sensors. Compared to other approaches, we propose a blind source separation scheme simpler than the ones based on phase extraction and complex steerable pyramids that still capable of disentangling local structural vibration from video measurement only. Moreover, a simple method to magnify and visualize independent vibration modes is introduced using the extracted modal information only. We validate our method by laboratory experiments on a bench-scale building structure and a cantilever beam. The results demonstrate that the proposed technique can decompose high-resolution modal parameters, visualize and reconstruct even those weakly-excited vibration modes.

Wide Swath and High Resolution Airborne HyperSpectral Imaging System and Flight Validation.

Wide Swath and High Resolution Airborne Pushbroom Hyperspectral Imager (WiSHiRaPHI) is the new-generation airborne hyperspectral imager instrument of China, aimed at acquiring accurate spectral curve of target on the ground with both high spatial resolution and high spectral resolution. The spectral sampling interval of WiSHiRaPHI is 2.4 nm and the spectral resolution is 3.5 nm (FWHM), integrating 256 channels coving from 400 nm to 1000 nm. The instrument has a 40-degree field of view (FOV), 0.125 mrad instantaneous field of view (IFOV) and can work in high spectral resolution mode, high spatial resolution mode and high sensitivity mode for different applications, which can adapt to the Velocity to Height Ratio (VHR) lower than 0.04. The integration has been finished, and several airborne flight validation experiments have been conducted. The results showed the system’s excellent performance and high efficiency.

Avaliação do alcance dinâmico de imagens digitalizadas – influência da resolução espacial e da modalidade de captura da imagem

The appearance of a digital image is very important for a correct interpretation and, consequently, for a effective diagnosis. Purpose: There are many factors that may influence the quality of a digital image. The process of digitalization must be analyzed to make sure that possible negative interferences will be eliminated. Methods: Some of these interferences include image spatial resolution and image capture mode. Their repercussion in the dynamic range of digital images was analyzed by the program Photoshop (Adobe Systems Incorporated, Mountain View, California, USA). Results: The results showed that for a digitalized image, a spatial resolution much superior it is not required. Conclusion: For the digital images, the signal/noise ratio (SNR) cannot be neglected.

Damage localization of beam structures using mode shape extracted from moving vehicle response

Mode shape curvature change has been regarded as a promising damage localization index (DLI). However, its application is limited by the requirement for high spatial resolution and reference mode shapes, and the central difference method induced low anti-noise ability. This paper aims to develop a new damage localization method by using the mode shapes extracted from moving vehicle response for beam structures without reference data. The first order mode shape with high spatial resolution in damaged state is extracted from the response measured on a moving vehicle via Hilbert transform (HT). Then regional mode shape curvature (RMSC) in damaged state which takes advantage of the high spatial resolution of mode shapes provided by moving vehicle test is defined to enhance the anti-noise ability. Subsequently the RMSC in undamaged state is estimated by the RMSC in damaged state and polynomial approximation under the assumption that RMSC in undamaged state has smooth surface. Finally an index is formulated based on RMSC before and after damage to localized damage. Numerical studies are conduced to investigate the effect of noise, moving velocity, uneven distribution of beam flexural rigidity, and road roughness on the accuracy of the proposed DLI.

MPISI: The neutron strain scanner materials probe for internal strain investigations at the SAFARI-1 research reactor

A modern neutron strain scanner instrument with crystallographic texture measurement capability has been established at the SAFARI-1 research reactor. This instrument, MPISI, has been benchmarked against the VAMAS Ring-and-Plug specimen, as well as in high spatial resolution mode using sub-millimeter beams. It is equipped with a double focused Si-multiwafer monochromator, sturdy high-precision sample manipulation stages, adjustable primary and secondary beam apertures interchangeable with radial collimators (RCs) on the secondary beam side and a 300 × 300 mm2 position sensitive neutron area detector. The RCs facilitate measurement of large specimens and interfaces. Variation in monochromator horizontal curvature allows optimization of the intensity (texture), resolution (peak broadening), or Figure-of-Merit (strain) with an achievable resolution of Δd/d ∼ 3 × 10−3. An Android based Wi-Fi hand-held control module in conjunction with lasers and theodolites aid with sample positioning and alignment. Data acquisition and control has been standardised on the SINQ Instrument Control Software. In-house developed data reduction software enables: flat field correction, geometric correction, vertical integration, data normalization, peak and entry-curve fitting, as well as multi-dimensional data visualization. Acquiring data against statistical criteria rather than time improves the overall instrument utilisation efficiency.

Finite element model updating of liquid rocket engine nozzle based on modal test results obtained from 3-D SLDV technique

In order to update the finite element model, the modal test results must be highly accurate since they are used as the basis. The major problems with traditional modal test method are limited measurement points and poor mode shape precision. In this paper, modal test based on 3-D Scanning Laser Doppler Vibrometry (SLDV) technique was carried out. High spatial resolution and accurate mode shapes were obtained, which is beneficial to subsequent correlation analysis and updating process. High order modal parameters were identified and more information can be added in the objective function. Due to the consistent coordinate system in modal test and finite element model, the measurement points and corresponding finite element nodes were easily matched in order to compare mode shapes. By means of a real liquid rocket engine nozzle, an integrated model updating process is presented from proper initial model, accurate modal test results, test/analysis correlation to automatic model updating. The single steps of detailed updating process are highlighted. The discrepancy between the finite element model predicted and the experiment measured modal parameters are minimized and satisfactory results were obtained.

Auditory responses to short-wavelength infrared neural stimulation of the rat cochlear nucleus.

Pulsed Infrared laser is well-known for its high spatial resolution and contact-free stimulation mode. In order to improve the current auditory brainstem implants (ABI), 980 nm-short-wavelength infrared light was applied to stimulate the cochlear nucleus of rats. Single neural activity from contralateral inferior colliculus was recorded during laser stimulation. Animal experimental results showed that 980 nm laser could not directly activate neurons in cochlear nucleus and a photo-acoustic response was observed during stimulation, however, 980 nm laser produces an inhibitory effect on neural responses to sounds; After we added carbon nanoparticles onto the surface of animal cochlear nucleus, 980 nm laser could directly stimulate neurons and no interference between adjacent recording channels was observed. These findings indicated that with the enhancement of carbon nanoparticles, short-wavelength infrared neural stimulation (SW-INS) might be an effective method to overcome the defects of current ABIs. With this method, a new type of optical ABI with transcutaneous stimulating method is quite promising.

Reference-free detection of minute, non-visible, damage using full-field, high-resolution mode shapes output-only identified from digital videos of structures

Detecting damage in structures based on the change in their dynamics or modal parameters (modal frequencies and mode shapes) has been extensively studied for three decades. The success of such a global, passive, vibration-based method in field applications, however, has long been hindered by the bottleneck of low spatial resolution vibration sensor measurements. The primary reason is that damage typically initiates and develops in local regions that need to be captured and characterized by very high spatial resolution vibration measurements and modal parameters (mode shapes), which are extremely difficult to obtain using traditional vibration measurement techniques. For example, accelerometers and strain-gauge sensors are typically placed at a limited number of discrete locations, providing low spatial resolution vibration measurements. Laser vibrometers provide high-resolution measurements, but are expensive and make sequential measurements that are time- and labor-consuming. Recently, digital video cameras—which are relatively low cost, agile, and able to provide high spatial resolution, simultaneous, pixel measurements—have emerged as a promising tool to achieve full-field, high spatial resolution vibration measurements. Combined with advanced vision processing and unsupervised machine algorithms, a new method has recently been developed to blindly and efficiently extract the full-field, high-resolution, dynamic parameters from the video measurements of an operating, output-only structure. This work studies the feasibility of performing damage detection using the full-field, very high spatial resolution mode shape (of the fundamental mode) blindly extracted from the video of the operating (output-only) structure without any knowledge of reference (healthy) structural information. A spatial fractal dimension analysis is applied on the full-field mode shape of the damaged structure to detect damage-induced irregularity. Additionally, the equivalence between the fractal dimension and the squared curvature (modal strain energy) of the mode shape curve, when of high spatial resolution, is mathematically derived. Laboratory experiments are conducted on bench-scale structures, including a building structure and a cantilever beam, to validate the approach. The results illustrate that using the full-field, very high-resolution mode shape enables detection of minute, non-visible, damage in a global, completely passive sensing manner, which was previously not possible to achieve.

Elemental Fractionation Studies of 193 nm ArF Excimer Laser Ablation System at High Spatial Resolution Mode

Abstract The limit of detection (LOD), ICP mass load effect, downhole induced fractionation and matrix effect of 193 nm ArF excimer laser ablation system at high spatial resolution were systematically investigated. Trace elements in GSD-1G, StHs6/80-G and NIST612 were measured at 10 μm spot size. The results showed that the LOD decreased with the increasing ablation diameter. In addition, the LOD of part of trace elements was in a range of 1–10 μg g −1 at 7 μm spot size. Mass load effect was negatively correlated with the corresponding oxide melting temperature, while positively correlated with the elemental 1 st ionization potential. Downhole fractionation was negligible when the ratio of ablation depth to spot size was smaller than 1:1. Matrix effect between NIST610, GSD-1G, ATHO-G and StHs6/80-G did not change in the spot size ranged from 10 μm to 50 μm. The analytical results of GSD-1G, StHs6/80-G and NIST612 at 10 μm spot size matched well with the reference values. Generally, 10 μm spatial resolution could satisfy the requirements of trace elements analysis.

Qualitative Time-of-Flight Secondary Ion Mass Spectrometry Analysis of Root Dentin Irrigated with Sodium Hypochlorite, EDTA, or Chlorhexidine

IntroductionSodium hypochlorite (NaOCl), chelating agents, and chlorhexidine (CHX), which are commonly used irrigants during endodontic treatment, have the potential to alter the physical and chemical properties of the dentin structure. The aim of this study was to use time-of-flight secondary ion mass spectrometry to qualitatively evaluate the chemical characteristics of dentin surface and compare it with dentin exposed to NaOCl, EDTA, or CHX. MethodsFour blocks of dentin from a root of a human maxillary molar were embedded in resin and trimmed with a microtome to expose the dentin. Samples were randomly assigned to 4 treatment groups: (1) no irrigation treatment (sample A), (2) 2.5% NaOCl (sample B), (3) 17% EDTA (sample C), and (4) 2% CHX (sample D). Dentin surfaces were analyzed by time-of-flight secondary ion mass spectrometry, which allowed characterization of dentin surface chemistry by both imaging and mass spectroscopic analysis obtained in high mass and spatial resolution modes. ResultsSample A revealed intense peaks characteristics of hydroxyapatite in addition to Na+, K+, CH4N+, CN−, CNO−, Mg+, F−, and HCO2− peaks. Sample B showed severely decreased CH4N+ and increased intensity of Cl−. Sample C lacked Ca+ and Mg+ and showed decreased PO2− and PO3−. Sample D exhibited a distinct presence of CHX. The spectral image of sample A displayed even distribution of Na+ and Ca+ on a smeared surface. The surfaces of samples B and D had patent dentinal tubules, whereas sample D showed an intense CHX signal. Sample C had some patent dentinal tubules and lacked Ca+. ConclusionsNaOCl removed protein components from the dentin matrix, EDTA removed calcium and magnesium ions from the dentin, and CHX formed an adsorbed layer on the dentin surface.