Phase Reconstruction Research Articles

Preparation and characterization of electromagnetic wave absorbing material from polymetallic vanadium titano-magnetite (VTM): Oriented phase transformation underlying formation mechanism

Polymetallic vanadium titano-magnetite (VTM) is recognized as one of the most refractory mineral resources because of its multiple-element composite symbiosis feature. Conventional carbothermic reduction and smelting separation treatment are characterized by high energy consumption and large greenhouse gas emissions. Considering the material attribute, an alternative and clean utilization of refractory VTM via the pyrometallurgically oriented phase transformation in air atmosphere to prepare the composite electromagnetic wave absorbing material was proposed for the first time in this work. The theoretical foundation of the oriented composite material design, phase transformation, microstructure and interfacial element migration, magnetism, electromagnetic properties, and wave absorbing properties were investigated via thermodynamic calculations, XRD, XPS, optical microscope, SEM‒EDS, VSM, and VNA analyses. Theoretical calculations indicated that the formation of composite ferrites was thermodynamically feasible over 1085 °C. In the oriented phase reconstruction, the symbiotic structure of the VTM was reconstructed via MnO2 addition at 1150 °C, and almost all the Fe, Mn, Ti, and V were concentrated in the composite ferrites, in which the Ti and V were doped in the octahedral structure (B site) of spinel-type crystalline structure. The as-purified composite ferrite material from the VTM+80%MnO2 mixture roasted at 1150 °C for 2 h showed good electromagnetism performance. A minimum RL peak of −50 dB was obtained at a veneer thickness of 11 mm, and the RL value less than −20 dB had a big frequency bandwidth of 9 GHz (frequency range of 8 GHz–17 GHz). It's inferred that this low-cost and abundant composite ferrite material can be economically applied in the construction industry. This work provided a clean and higher-value application of abundant refractory polymetallic VTM resources.

Single-branched stent-graft with on-table fenestration for endovascular repair of primary retrograde type A aortic dissection: A multicenter retrospective study.

This study aims to evaluate the feasibility, efficacy, and safety of a single-branched stent-graft with on-table fenestration for primary retrograde type A aortic dissection (RTAD) during thoracic endovascular aortic repair (TEVAR). From January 2019 to December 2021, 36 patients with primary RTAD from five tertiary hospitals received medical management in the acute phase. They underwent TEVAR with a proximal zone 1 landing for aortic arch reconstruction in the subacute phase, using a fenestration technique on a single-branched stent-graft. Nearly 2 weeks after admission, computed tomography angiography (CTA) was re-examined to evaluate the thrombosis status of retrograde false lumen (FL). The primary outcomes were technical success, patency of the target branch arteries, and absence of type Ia endoleaks. The second outcomes were stent-graft-related complications and all-cause mortality. The mean age was 56.2 ± 11.3 years, and 29 (80.6%) were male. After a median interval of 18.0 [interquartile range (IQR), 17.0-20.3] days of medical treatment, the partial and complete thrombosis of proximal FL rates increased to 52.8% and 47.2%, respectively. One patient (2.8%) experienced postoperative type Ia endoleaks, and was successfully re-treated using coli and Onyx glue. The median hospital stay was 20.5 (IQR, 18.0-23.0) days. The overall technical success rate was 100%. The median follow-up time was 31.5 (IQR, 29.8-34.0) months. There was one death (2.8%) due to gastrointestinal bleeding. Distal aortic segmental enlargement (DASE) occurred in two (5.6%) patients. No major complications or recurrent dissections in the proximal landing zone were recorded during follow up. The retrograde FL in primary RTAD could realize partial or complete thrombosis after medical management in the acute phase, and it might be regarded as a valid proximal landing zone for endovascular repair. The single-branched stent graft with on-table fenestration performed in the subacute phase may be feasible strategy in selective primary RTAD patients.

Fundamental study on the preparation of insulating ceramics via the phase reconstruction of phosphate tailings

Insulating ceramics with anorthite and diopside as the main crystal phases were manufactured using phosphate tailings, coal gangue, and quartz as raw materials, which were fired at 1160–1190 °C for 2 h. The structure and micromorphology of the samples were investigated using X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Dense ceramic samples exhibited an apparent porosity of less than 0.3%, densities of 2.64–2.86 g/cm3, bending strength of 127.71–172.73 MPa, dielectric constants of 6.98–7.79, and dielectric losses of 0.0086–0.0024 at 20 °C and frequency of 1 MHz. The effects of impurity elements on ceramic properties are determined. The excellent electrical properties can be attributed to the solid solution of iron in the crystalline phases, such as diopside, which reduce leakage conductance in ceramics and alleviate the influence of relaxation and space charge polarization on the electrical properties of ceramics. This study provides a new strategy for preparing high-value insulating ceramics from solid waste.

Phase Reconstruction of Low-Energy Electron Holograms of Individual Proteins.

Low-energy electron holography (LEEH) is one of the few techniques capable of imaging large and complex three-dimensional molecules, such as proteins, on the single-molecule level at subnanometer resolution. During the imaging process, the structural information about the object is recorded both in the amplitude and in the phase of the hologram. In low-energy electron holography imaging of proteins, the object's amplitude distribution, which directly reveals molecular size and shape on the single-molecule level, can be retrieved via a one-step reconstruction process. However, such a one-step reconstruction routine cannot directly recover the phase information encoded in the hologram. In order to extract the full information about the imaged molecules, we thus implemented an iterative phase retrieval algorithm and applied it to experimentally acquired low-energy electron holograms, reconstructing the phase shift induced by the protein along with the amplitude data. We show that phase imaging can map the projected atomic density of the molecule given by the number of atoms in the electron path. This directly implies a correlation between reconstructed phase shift and projected mean inner potential of the molecule, and thus a sensitivity to local changes in potential, an interpretation that is further substantiated by the strong phase signatures induced by localized charges.

Cell image reconstruction using digital holography with an improved GS algorithm.

Digital holography is an effective technology in image reconstruction as amplitude and phase information of cells can be acquired without any staining. In this paper, we propose a holographic technique with an improved Gerchberg-Saxton (GS) algorithm to reconstruct cell imaging based on phase reconstruction information. Comparative experiments are conducted on four specific models to investigate the effectiveness of the proposed method. The morphological parameters (such as shape, volume, and sphericity) of abnormal erythrocytes can be obtained by reconstructing cell hologram of urinary sediment. Notably, abnormal red blood cells can also be detected in mussy circumstances by the proposed method, owing to the significantly biophysical contrast (refractive index distribution and mass density) between two different cells. Therefore, this proposed method has a broad application prospect in cell image reconstruction and cell dynamic detection.

Pd nanocubes supported on SiW12 @Co-ZIF Nanosheets for High-efficiency rupture of ether bonds in model and actual lignin

A rational design of the intrinsic lattice structure of catalysts is vitally important to address catalytic performance. Herein is reported a top-down synthesis for the fabrication of a bifunctional metallic catalyst. First, palladium nanocubes with (100) lattices planes were synthesized through a shape-control strategy; next, the as-synthesized Pd/Co-ZIF was used as a template for in-situ phase reconstruction by a spontaneous phase transformation process in the presence of H4SiW under solvothermal conditions. Ultimately, formation of 3D hierarchical flower-like bimetallic nitride nanosheets (SiW12 @Pd/Co-ZIF-NS) were generated because of this process. The SiW12 @Pd/Co-ZIF-NS catalyst not only displays excellent catalytic transfer hydrogenolysis for C-O bond cleavage of lignin dimeric substrates, but also maintains superior recycling durability due to an encapsulation phenomenon preventing aggregation. Finally, the resulting nanocomposites exhibit superior activity and good size selectivity toward catalytic transfer hydrogenolysis of the actual lignin substrates to produce a significant amount of low-molecular-weight aromatic compounds.

Mineralogical characteristics of copper smelting slag affecting the synchronous flotation enrichment of copper and arsenic

Synchronous enrichment of copper and arsenic has become a newly emerging and significant problem during copper smelting slag (CSS) flotation, which affects environmental safety and CSS utilization. This study on CSS and its flotation products revealed the factors that affect the flotation enrichment of copper and arsenic from a mineralogy perspective. Mineralogical characteristic studies revealed that copper existed primarily in the form of matte with excellent floatability, whereas arsenic was primarily dissolved or wrapped in glassy silicates without floatability. The second occurrence phase of copper and arsenic, copper–arsenic alloy, was closely embedded with gangue minerals, which increased the difficulty of enriching copper and arsenic. Sequential extraction and X-ray photoelectron spectroscopy analysis indicated that the floatability of copper was better than that of arsenic. Flotation tests showed that copper recovery could reach 82.79 %, whereas arsenic recovery was only 40.83 %, which further confirmed that copper and arsenic could not be enriched synchronously. Mineral phase reconstruction was proposed as a potential scheme to enhance arsenic recovery. Arsenic was released from glassy silicates and combined with a copper-bearing phase to form copper–arsenic alloy during mineral phase reconstruction, which significantly increased arsenic recovery by 39.34 % and slightly increased copper recovery. The synchronous enrichment of copper and arsenic effectively reduces the total arsenic emission during copper pyrometallurgy, thereby alleviating the pressure of environmental pollution caused by CSS flotation tailings. This work provides a scientific reference for CSS processing toward recycling and harmlessness.

Fast numerical propagation in high-NA imaging using the resampling angular spectrum method.

Numerical propagation calculation is a fundamental research topic in optical engineering. The standard angular spectrum method (ASM) is accurate but time- and memory-consuming, especially for high-NA systems. In this work, we propose a fast and simple numerical propagation method, the resampling ASM (RS-ASM). Numerical propagation can be accelerated by combining a resampling technique with interpolation methods in the angular spectrum domain of a constrained object at the focal plane. RS-ASM has three main advantages: simple implementation, faster calculation than the standard ASM, and SNR enhancement. Here we validate RS-ASM using theory, simulation and experiment. Using the "bilinear" ASM with a proper resampling factor can result in a speed-up factor of up to 20x (for a transformation from the angular spectrum to the E field) and 4x (for a transformation from E field to the angular spectrum), together with a SNR improvement of approximately 2x. For an application example of Gerchberg-Saxton phase reconstruction, the "bilinear" RS-ASM can converge 2.6x faster than the standard ASM.

Coating Ni-rich cathode with an amorphous carbon for improving the stability and electrochemical performance

Layer-structured Ni-rich cathodes are promising candidates for high-energy-density lithium-ion batteries (LIBs). However, Ni-rich cathodes still suffer from fast capacity fading and voltage dropping issues due to surface phase reconstruction, oxygen release, and intergranular/intragranular cracking problems. To tackle these issues, herein, we coating Ni-rich cathodes with an amorphous carbon layer by using a liquid phase polymer acrylonitrile telomer (ANT) as the precursor companied with a post-annealing strategy. As a result, the rate performance, long cycling performance and high voltage performance of carbon coated NMC811 batteries are greatly improved. The insight mechanism was disclosed by advanced characterization techniques including focused ion beam, high-resolution transmission electron microscopy, scanning electron microscope, and X-ray photoelectron spectroscopy (XPS). A severe intergranular/intragranular cracking was found in bare NMC811 cathode after long-term cycling, indicating that bare NMC811 experienced serious surface phase reconstruction, oxygen release, and electrolyte decomposition. XPS results indicate that an unstable cathode electrolyte interphase (CEI) layer was formed under high voltage at the interface between bare NMC811 and the electrolyte. With the protection of amorphous carbon, the intergranular/intragranular cracking problem is alleviated, and a LiF-rich CEI layer was created at the electrode/electrolyte interface, therefore, rendering a high voltage stable and long-term cycling performance NMC811 batteries.

Low-intensity illumination for lensless digital holographic microscopy with minimized sample interaction.

Exposure to laser light alters cell culture examination via optical microscopic imaging techniques based on label-free coherent digital holography. To mitigate this detrimental feature, researchers tend to use a broader spectrum and lower intensity of illumination, which can decrease the quality of holographic imaging due to lower resolution and higher noise. We study the lensless digital holographic microscopy (LDHM) ability to operate in the low photon budget (LPB) regime to enable imaging of unimpaired live cells with minimized sample interaction. Low-cost off-the-shelf components are used, promoting the usability of such a straightforward approach. We show that recording data in the LPB regime (down to 7 µW of illumination power) does not limit the contrast or resolution of the hologram phase and amplitude reconstruction compared to regular illumination. The LPB generates hardware camera shot noise, however, to be effectively minimized via numerical denoising. The ability to obtain high-quality, high-resolution optical complex field reconstruction was confirmed using the USAF 1951 amplitude sample, phase resolution test target, and finally, live glial restricted progenitor cells (as a challenging strongly absorbing and scattering biomedical sample). The proposed approach based on severely limiting the photon budget in lensless holographic microscopy method can open new avenues in high-throughout (optimal resolution, large field-of-view, and high signal-to-noise-ratio single-hologram reconstruction) cell culture imaging with minimized sample interaction.

Internal anatomy of a fossilized embryonic stage ofthe Cambrian-Ordovician scalidophoran Markuelia.

The Wangcun fossil Lagerstätte in Hunan, South China, has yielded hundreds of fossilized embryos of Markuelia hunanensis representing different developmental stages. Internal tissues have only rarely been observed, impeding further understanding of the soft tissue anatomy, phylogenetic affinity and evolutionary significance of Markuelia. In this study, we used synchrotron radiation X-ray tomographic microscopy (SRXTM) to study a new collection of fossil embryos from the Wangcun fossil Lagerstätte. We describe specimens exhibiting a spectrum of preservation states, the best of which preserves palisade structures underneath the cuticle of the head and tail, distinct from patterns of centripetal mineralization of the cuticle and centrifugal mineralization of hypha-like structures, seen elsewhere in this specimen and other fossils within the same assemblage. Our computed tomographic reconstruction of these mineralization phases preserves the gross morphology of (i) longitudinal structures associated with the tail spines, which we interpret as the proximal ends of longitudinal muscles, and (ii) a ring-shaped structure internal to the introvert, which we interpret as a ring-shaped brain, as anticipated of the cycloneuralian affinity of Markuelia. This is the first record of a fossilized nervous system in a scalidophoran, and the first instance in Orsten-style preservation, opening the potential for further such records within this widespread mode of high-fidelity three-dimensional preservation.

Whether magnetization roasting requires complete phase reconstruction of iron minerals: A study of phase transition and microstructure evolution

Previous magnetization roasting studies usually pursued whole phase reconstruction of iron minerals. This research innovatively proposed a surface magnetization roasting technology requiring only partial phase reconstitution of hematite to decrease carbon emissions. Two hematite samples with narrow particle size distributions (45–74 μm and 74–150 μm) were adopted to better control the magnetite layer thickness. The optimal magnetic separation index was obtained when the relative thickness of the magnetite layer was only approximately 0.3000 and the magnetite content in the roasted product was only about 40%. The remaining hematite still needed a long time to be reduced to magnetite. The hematite on the particle surface was preferentially reduced to magnetite. The surface magnetite can provide magnetic force during the magnetic separation process to recover the roasted particles. The efficient iron recovery was realized through surface magnetization roasting, which only required partial reduction of hematite, consuming less energy and reductant.

Phase stability and enhanced mechanical properties of ferro-titanium slag to aluminum titanate ceramics

• The addition of ferro-titanium slag improves the strength of the material. • Impurities in ferrotitanium slag form solid solution with aluminum titanate. • The formation of solid solution inhibits the decomposition of aluminum titanate. • Recycling and harmless utilization of metallurgical waste slag. Ferro-titanium slag is a waste slag from ferro-titanium alloy smelting. It has high strength and has been observed to act as a reinforcing phase in multiphase materials, of which ferro-titanium slag powders were chosen to inhibit the thermal decomposition of AT ceramic in 800–1300 °C temperature range and improve its mechanical strength. It was shown that Si 4 + , Fe 3 + and Ti 4 + ions in ferro-titanium slag can partially replace Al 3 + ion in AT to form an ATFS (the AT ceramic doped with SiO 2 and Fe 2 O 3 ) solid solution, which inhibited the decomposition of AT. In addition, the formation of CA 6 phase contained from phase reconstruction of ferro-titanium slag further reinforced the mechanical properties of the AT ceramic. When 50 wt% ferro-titanium slag was added, the CA 6 enhanced AT multiphase ceramic improved phase stability and reaches mechanical properties (≈14 MPa).

High quality of an absolute phase reconstruction for coherent digital holography with an enhanced anti-speckle deep neural unwrapping network.

It is always a challenge how to overcome speckle noise interference in the phase reconstruction for coherent digital holography (CDH) and its application, as this issue has not been solved well so far. In this paper, we are proposing an enhanced anti-speckle deep neural unwrapping network (E-ASDNUN) approach to achieve high quality of absolute phase reconstruction for CDH. The method designs a special network-based noise filter and embeds it into a deep neural unwrapping network to enhance anti-noise capacity in the image feature recognition and extraction process. The numerical simulation and experimental test on the phase unwrapping reconstruction and the image quality evaluation under the noise circumstances show that the E-ASDNUN approach is very effective against the speckle noise in realizing the high quality of absolute phase reconstruction. Meanwhile, it also demonstrates much better robustness than the typical U-net neural network and the traditional phase unwrapping algorithms in reconstructing high wrapping densities and high noise levels of phase images. The E-ASDNUN approach is also examined and confirmed by measuring the same phase object using a commercial white light interferometry as a reference. The result is perfectly consistent with that obtained by the E-ASDNUN approach.

Digital Reconstruction of Engineered Austenite: Revisiting Effects of Grain Size and Ausforming on Variant Selection of Martensite

In this work, the variant selection of martensite in a stainless maraging steel was investigated by electron backscattering diffraction and a new protocol of parent phase reconstruction. The reconstruction protocol enables digital austenite reversion into prior austenite microstructure and provides information of variant selection from a large number of austenite grains. It was found that strong variant selection occurred when the prior austenite grains were significantly refined in annealing or severely deformed by ausforming. When the prior austenite grain size was finer than 20 μm, it was found that a pair of twinned variants dominated in one packet, which dominates the prior austenite grain. This finding is explained by the inefficient space left by the early transformed martensite in the dominant packet. In contrast, variants with the same Bain orientation occupied most of the space of the austenite when the strain of the austenite exceeded 50%. The accumulated microbands on the 1 1 1 plane acted as nucleation sites of specific variants of martensite. This work provides statistical results to revisit the variant selection of martensitic transformation with the assistance of computational crystallography.

Fabrication technology for light field reconstruction in glasses-free 3D display

ABSTRACT Light field 3D display has attracted great attention as the hardware interface for a virtual 3D application. The design and fabrication of light-modulating structures directly affect the authenticity of the reconstructed 3D image. The critical challenges in 3D display, such as visual fatigue, limited motion parallax, and insufficient light efficiency, are closely related to the inaccurate phase or angular reconstruction of the virtual light field. While the designs of light field modulators are widely introduced in all kinds of studies, the importance of fabrication for 3D display is usually under-estimated. Large format, small feature size, and high precision in shape are the three critical requirements of fabrication for 3D display. In this paper, we focus on the fabrication technologies for light-modulating structures. Fabrication tools for both microstructures and nanostructures are introduced. The fabrication capability, critical challenges and its applications in light field 3D display are discussed. Finally, the future development of 3D display related fabrication technologies are highlighted.

Improving the phase reconstruction accuracy of simultaneous phase-shifted lateral shearing interferometry using a polarization redundant sub-region interpolation method.

In a simultaneous phase-shifted lateral shearing interferometry, a division of focal plane polarization camera is generally used as the phase-shifting device. However, acquiring simultaneous phase-shift interferograms in a single frame suffers from a lack of spatial resolution, significantly affecting the phase reconstruction accuracy. A polarization redundant sub-region interpolation (PRSI) method is proposed to solve this problem. This interpolation method distinguishes smooth regions from stripe fringe regions by calculating the polarization redundancy error of the synchronous phase shift interferogram. After sub-regional processing, resolution reconstruction is performed in the smoothed area using a fast convolutional bilinear interpolation method. In the streak detail region, the resolution reconstruction is performed based on the strength of the correlation between the orthogonal and non-orthogonal polarization channels crossing the streak region. The PRSI method can quickly reconstruct the lost pixels and accurately recover the stripe detail information. Experiment results show that the proposed interpolation method outperforms the existing dominant methods in terms of visual reconstruction effect and quantitative index of phase reconstruction.

A comprehensive quality assurance procedure for 4D CT commissioning and periodic QA.

The 4D computed tomography (CT) simulation is an essential procedure for tumors exhibiting breathing-induced motion. However, to date there are no established guidelines to assess the characteristics of existing systems and to describe meaningful performance. We propose a commissioning quality assurance (QA) protocol consisting of measurements and acquisitions that assess the mechanical and computational operation for 4D CT with both phase and amplitude-based reconstructions, for regular and irregular respiratory patterns. The 4D CT scans of a QUASAR motion phantom were acquired for both regular and irregular breathing patterns. The hardware consisted of the Canon Aquilion Exceed LB CT scanner used in conjunction with the Anzai laser motion monitoring system. The nominal machine performance and reconstruction were demonstrated with measurements using regular breathing patterns. For irregular breathing patterns the performance was quantified through the analysis of the target motion in the superior and inferior directions, and the volume of the internal target volume (ITV). Acquisitions were performed using multiple pitches and the reconstructions were performed using both phase and amplitude-based binning. The target was accurately captured during regular breathing. For the irregular breathing, the measured ITV exceeded the nominal ITV parameters in all scenarios, but all deviations were less than the reconstructed slice thickness. The mismatch between the nominal pitch and the actual breathing rate did not affect markedly the size of the ITV. Phase and normalized amplitude binning performed similarly. We demonstrated a framework for measuring and quantifying the initial performance of 4D CT simulation scans that can also be applied during periodic QAs. The regular breathing provided confidence that the hardware and the software between the systems performs adequately. The irregular breathing data suggest that the system may be expected to capture in excess the target motion and geometry, but the deviation is expected to be within the slice thickness.

Experimental Exposure Evaluation From the Very Close Near- to the Far-Field Using a Multiple-Multipole Source Reconstruction Algorithm

Exposure assessment of wireless devices operating at ≥6 GHz requires measurement of power density (PD) from a distance of 2 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\geq \lambda $ </tex-math></inline-formula> /25) from the surface of the device (reactive near field) to the far field with minimal uncertainties. The challenges are field distortion and backscattering by the probe, spatial resolution, sensitivity, isotropy, and phase accuracy. In addition, the surfaces of the device may not be planar. Today, methods based on phaseless amplitude measurements are widely applied using plane-to-plane phase reconstruction (PR) to obtain the field phasors. The obtained phasors in conjunction with Maxwell’s equations allow to evaluate the fields in the whole volume of interest. Although these methods meet the PD compliance criteria for flat surfaces at distances as close as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda /5$ </tex-math></inline-formula> , they are unsuited for curved surfaces and closer distances. To overcome these limitations, we present a method based on a multiple-multipole expansion for accurate PD evaluation in all field regions using sparse phaseless electric field measurements. We construct a physically relevant vectorial basis in terms of elementary electric or magnetic dipoles and optimize their amplitudes such that the measured fields are reproduced with minimal error. The proposed procedure yields current distributions that resemble the physical radiation source and accurately reconstruct the electromagnetic field from the (reactive) near-field to the far-field regions with an uncertainty of <0.6 dB. Our approach does not pose any geometric requirements to the measurement or evaluation surfaces and thus supports conformal assessments, providing a potential solution for accurate PD evaluation of 5G devices and beyond.

Robust Phase Reconstruction Using Random Three Step Phase-Shift in Wavelength Tuning Interferometer

The standard stochastic two-step phase shift phase demodulation method analyzes the tangent function of the phase to be measured to extract the phase to be evaluated. It is necessary to eliminate the background light intensity of interference fringes, which has a significant impact on phase reconstruction accuracy. A random three-step phase shift algorithm (RTP) is suggested in this study. The phase shift between two adjacent interference fringes is extracted using the least squares approach in conjunction with a K-order twodimensional polynomial. Additionally, it employs the interference fringe graph’s difference operation to reduce the background light intensity and actualize the restoration of the measurement phase. The experimental and simulations results reveal that phase shift, luminous non-uniformity, and random noise have little effect on the random three-step phase shift method and have strong environmental adaptability.