Annular Imaging Research Articles

Ehrigite, Bi8Te3, a New Member of the Tetradymite Group

Abstract Ehrigite, Bi8Te3, is a new member of the tetradymite group and crystallizes in the trigonal crystal system (space group: , #166). Its cell dimensions are a = 4.519(6) Å, c = 65.182(24) Å, Z = 3, and V = 1152.771(7.554) Å3. Ehrigite occurs as sub-100-micron-sized grains in hedenbergite skarn from the abandoned Good Hope gold mine, Hedley district, British Columbia, Canada. The mineral and name have been approved by the IMA Commission on New Minerals and Mineral Nomenclature (proposal 2023-074). Ehrigite is compositionally and structurally distinct from hedleyite, Bi7Te3, with which it coexists. Ehrigite is opaque, with a pale gray color in reflected light. Reflectance is higher than tetradymite and slightly higher than hedleyite. It appears gray against native bismuth. The ehrigite structure consists of a single 11-atom layer visualized in atomic-scale high-angle annular dark field scanning transmission electron microscope images and further constrained from ab initio total energy calculations and structure relaxation using density functional theory using the measured parameters as input data. Scanning transmission electron microscope simulations also closely match the crystal structure model and images. Phases of the tetradymite and related modular mineral groups are well suited to visualization, indexing, and diffraction using a high-angle annular dark field scanning transmission electron microscope. The addition of density functional theory methodology to corroborate and refine structural characteristics provides a valuable approach for understanding these complex yet predictable minerals.

Vertically Stacked Amorphous Ir/Ru/Ir Oxide Nanosheets for Boosted Acidic Water Splitting.

Integrating multiple functional components into vertically stacked heterostructures offers a prospective approach to manipulating the physicochemical properties of materials. The synthesis of vertically stacked heterogeneous noble metal oxides remains a challenge. Herein, we report a surface segregation approach to create vertically stacked amorphous Ir/Ru/Ir oxide nanosheets (NSs). Cross-sectional high-angle annular darkfield scanning transmission electron microscopy images demonstrate a three-layer heterostructure in the amorphous Ir/Ru/Ir oxide NSs, with IrOx layers located on the upper and lower surfaces, and a layer of RuOx sandwiched between the two IrOx layers. The vertically stacked heterostructure is a result of the diffusion of Ir atoms from the amorphous IrRuOx solid solution to the surface. The obtained A-Ir/Ru/Ir oxide NSs display an ultralow overpotential of 191 mV at 10 mA cm-2 toward acid oxygen evolution reaction and demonstrate excellent performance in a proton exchange membrane water electrolyzer, which requires only 1.63 V to achieve 1 A cm-2 at 60 °C, with virtually no activity decay observed after a 1300 h test.

Atomic structure of clusters and GP-zones in an Al-Mg-Si alloy

The structures of atomic clusters and GP-zones preceding precipitation in an Al-0.70Mg-0.85Si-0.15Fe-0.25Mn (wt. %) alloy have been investigated by annular dark field scanning transmission electron microscopy imaging and density functional theory calculations. One analysed condition consisted of one-month natural aging, and another was in a pre-baked state after 24 h aging at 90 °C. To quantify the effect of clusters and GP-zones on microstructure development during a subsequent isothermal artificial aging at 185 °C, hardness evolution was measured, and precipitate statistics was performed at the peak hardness corresponding to 5 h aging. Several types of clusters and GP-zones have been observed and based on structure and visual appearance named 'Disordered Frank-Kasper', 'Square', 'Binocular', and 1β", 2β", 3β", 4β". The first four are most common in the natural aged condition and are associated with a well-known influence on the initial hardness evolution. The last three are fractions of the hardening β" phase and refer to the number of structural units they contain. These GP-zones have an increased density in the pre-baked condition, leading to a rapid increase in hardness during artificial aging and to a finer microstructure of high-density small needle precipitates at peak hardness.

Ultrasound Findings with Bedside Ultrasound of Heart Failure with Preserved LVEF

Heart failure with preserved ejection fraction (HFpEF), formerly termed diastolic heart failure, constitutes nearly half the heart failure cases. Patients may exhibit acute heart failure symptoms, yet bedside echocardiograms might indicate normal left ventricular systolic function, potentially leading to the premature exclusion of heart failure as a differential diagnosis. This review delves into fundamental echocardiographic principles associated with diastolic dysfunction, crucial for recognition in HFpEF patients. Specifically, it explores the VALVE protocol, a stepwise approach tailored for the exigent nature of emergency departments. Acquiring accurate imaging windows in acutely ill patients poses a challenge, emphasizing the significance of precise measurements to avoid errors. Techniques such as E-point septal separation (EPSS) must be meticulously positioned for ejection fraction determinations. The discussion focuses on key metrics outlined in the VALVE protocol, encompassing ventricular function, annular tissue Doppler imaging (TDI) measurements, left atrium volume, mitral valve velocities, and the E/e0 ratio as indicators of diastolic dysfunction in HFpEF.

STEM Structural Investigation of RE‐Au‐Si 1/1 Approximants

AbstractRE‐Au‐Si (RE=Ho, Tb) systems are 1/1 Tsai‐type quasicrystalline approximants with a cluster center decoration that can vary from a disordered tetrahedron to a rare‐earth atom. The local atomic structure of three different samples was observed by scanning transmission electron microscopy and interpreted in the light of high‐angle annular dark field simulated scanning transmission electron microscopy images. It is found that the combination of these two methods allows to identify differences in the chemical decoration of the cluster centers through quantitative analysis of line profiles.

Direct wavefront reconstruction with the cone wavefront sensor using the inverse radon transform.

The cone wavefront sensor consists of a cone (or axicon) placed at the focal plane of the imaging system, from which an annular intensity image is formed. Typically, the wavefront phase is estimated using inversion of an interaction matrix relating the intensity image to different aberration modes. In this paper, we show that the intensity image for the cone wavefront sensor is related to the radon transform of the wavefront phase. A reconstruction method using the inverse radon transform (filtered back-projection) is shown to be able to directly approximate the wavefront phase without the need for an interaction matrix for small wavefront aberrations.

Grain structure and co-precipitation behavior of high-Zn containing Al–Zn–Mg–Cu aluminium alloys during deformation via high-temperature upsetting-extrusion

A study on the deformation behavior with increase in strain during upsetting-extrusion (UE) was studied (i.e., No-UE, Small-UE, and Large-UE strains) at 350 °C in Al-8.9Zn-2.2Mg-2.1Cu-0.14Zr-0.02Sc (wt%) alloys to evaluate the strengthening effects of grain size/texture and co-precipitation for different ageing (i.e., as-received, T4, and T6 aging) conditions. In as-received samples, electron back-scattered diffraction observations revealed that increasing UE strain enhances the formation of continuous and discontinuous dynamic recrystallization grains. This reduces the size difference between fine and coarse grains in bimodal structure and produces stronger copper/cubic texture. In small angle X-ray scattering (SAXS), a large UE strain brings about more fraction of Y-phase and GP zones. In T4 Large-UE samples, SAXS indicated higher size stability of disk-like Y-phase. High-angle annular dark field scanning transmission electron microscopy images revealed five-layered atomic arrangement of a unit cell of Y-phase, where the center layer was composed of Al and sandwiched layers, 2Cu/2Zn/2Cu and Al/ZnCu/ZnCu/Al. In T6 Large-UE samples, it was observed that the growth of Y-phase is accompanied by intrinsic atomic shift along the [101̅0]Y-phase direction. Furthermore, SAXS quantitatively showed size evolution of η'/η precipitates and formation of a higher aspect ratio of Y-phase. The collective effects of finer bimodal grain structure, stronger fiber texture, and co-precipitation of Y-phase and η'/η precipitates provide evidence higher ultimate tensile strength (∼766 ± 5 MPa) and superior strain (∼10.9 ± 0.4) of large-UE strain samples under T6 ageing.

A simple Bessel module with tunable focal depth and constant resolution for commercial two-photon microscope

The volumetric imaging of two-photon microscopy expands the focal depth and improves the throughput, which has unparalleled superiority for three-dimension samples, especially in neuroscience. However, emerging in volumetric imaging is still largely customized, which limits the integration with commercial two-photon systems. Here, we analyzed the key parameters that modulate the focal depth and lateral resolution of polarized annular imaging and proposed a volumetric imaging module that can be directly integrated into commercial two-photon systems using conventional optical elements. This design incorporates the beam diameter adjustment settings of commercial two-photon systems, allowing flexibility to adjust the depth of focus while maintaining the same lateral resolution. Further, the depth range and lateral resolution of the design were verified, and the imaging throughput was demonstrated by an increase in the number of imaging neurons in the awake mouse cerebral cortex.

Right ventricular function in patients with significant tricuspid regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Aim The aim of this meta-analysis was to systematically investigate the prognostic value of right ventricular (RV) function in all-comers patients with significant (at least moderate, ≥ 2+) tricuspid regurgitation (TR). Background Chronic significant TR imposes a volume overload to the RV leading to a progressive RV dilatation and dysfunction. A comprehensive assessment of RV function is of paramount importance to guide the therapeutic management of these patients; however, it remains challenging, particularly in presence of altered loading conditions. Methods MEDLINE, ISI Web of Science, and SCOPUS databases were searched for studies published up to July 2022. Studies reporting data on at least one echocardiographic RV function parameter and outcome in patients with significant TR were included. This study was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) requirements. The primary endpoint was all-cause long-term mortality (more than one year). Results Out of 3,152 studies, a total of 10 were included in the analytic synthesis, enrolling 3435 subjects. The median follow-up in our study population was 28 [22 – 70] months. All-cause long-term mortality was 40% (95% confidence interval [CI]: 32–49%, p = 0.028; Figure 1). To explore the potential impact of effect size modifiers on all-cause long-term mortality, we performed a meta-regression analysis of the baseline characteristics of the included studies. At long-term, a significant relation was found between RV fractional area change (RV-FAC), tricuspid annular plane systolic excursion (TAPSE), tricuspid annular tissue doppler imaging systolic velocity (TDI s’) and mortality. In particular, RV-FAC was associated with reduced incidence of all-cause mortality [7 studies enrolling 2,611 subjects, intercept 5.18, slope −0.15, P = 0.007; Figure 2]; whereas both TAPSE and TDI s’ were unsatisfactory to predict the outcome in these patients [TAPSE 9 studies enrolling 2,891 subjects, intercept 1.73, slope −0.12, P = 0.36; TDI s’ 5 studies enrolling 1429 subjects, intercept −2.06, slope 0.15, P = 0.78]. Interestingly, diabetes mellitus (DM) and hyperlipidaemia were associated with an increased risk of mortality [DM 9 studies enrolling 3371 subjects, intercept −2.62, slope 0.09, P = 0.004; hyperlipidaemia 6 studies enrolling 2338 subjects, intercept −2.91, slope 0.05, P = 0.01]. Conclusions Significant TR is associated with increased risk of all-cause. To our knowledge, this is the first study to demonstrate that only RV-FAC, and not conventional echocardiographic indexes of RV longitudinal function, correlates with adverse outcomes in patients with significant TR.

Full Metal Species Quantification of Supported Catalysts: Beyond Metal Dispersion.

Metal dispersion is a key concept in heterogeneous catalysis. The conventional approaches for its estimation strongly rely on chemisorption with different probe molecules. Albeit they can generally provide an 'averaged' value in a cost-effective manner, the inhomogeneity of the metal species and the complicated metal-support interactions pose formidable challenges for the accurate determination. Full metal species quantification (FMSQ) is introduced as an advanced method to depict the whole distribution of the metal species, ranging from single atoms to clusters and nanoparticles, in a practical solid catalyst. In this approach, automated analysis of massive high-angle annular dark field scanning transmission electron microscopic images is realized through algorithms specialized in combining the electron microscopy-based atom recognition statistics and deep learning-driven nanoparticle segmentation. In this Concept article, different techniques for determining the metal dispersion are discussed with their pros and cons. FMSQ is highlighted for it can circumvent the drawbacks of conventional approaches, allowing more reliable structure-performance relationships beyond the metal size.

Unusual structural rearrangement and superconductivity in infinite layer cuprate superlattices

Epitaxial stabilization of thermodynamically metastable phases and advances in atomic control of complex oxide thin-film growth can be used effectively for realizing novel phenomena and as an alternative for bulk synthesis under extreme thermodynamic conditions. Here, we investigate infinite layer (IL) based cuprate superlattices, where 7--8 unit cells of ${\mathrm{Sr}}_{0.6}{\mathrm{Ca}}_{0.4}\mathrm{Cu}{\mathrm{O}}_{2}$ (SCCO) are sandwiched between ultrathin spacer layers of $\mathrm{SrTi}{\mathrm{O}}_{3}$ (STO), $\mathrm{SrRu}{\mathrm{O}}_{3}$, or $\mathrm{BaCu}{\mathrm{O}}_{2}$ (BCO) and only observe superconductivity in the pure [SCCO/BCO] superlattice (SL) without spacer layers. Apparently, the insertion of an additional STO spacer layer in the latter SL prevents the occurrence of superconductivity. The observed superconductivity in [SCCO/BCO] SL is discussed in terms of a structural model involving the interplay between the $\mathrm{Cu}{\mathrm{O}}_{2}$ plane and the CuO chain similar to the bulk $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ superconductor. The structural origin was found by the identification of a metastable IL-$\mathrm{BaCu}{\mathrm{O}}_{2}$ variant, which deviates highly from its parent bulk crystal structure and exhibits a relatively larger out-of-plane lattice parameter (around $7\phantom{\rule{0.16em}{0ex}}\AA{}$) when sandwiched with SCCO in the form of [SCCO/BCO] SL. However, this variant is absent when STO spacer layers are introduced between SCCO and BCO layers. X-ray absorption spectra of the Cu $L$ edge for BCO exhibits a slightly higher energy satellite peak as compared to the $3{d}^{9}L$ Zhang-Rice character observed in SCCO. This result indicates the existence of contrasting plane and chain-type Cu-O blocks in SCCO and BCO, respectively, which is further corroborated using annular bright field scanning transmission electron microscopy imaging. This work unravels an unexpected structure of BCO which helps in realizing superconductivity in [SCCO/BCO] SL and provides a wider perspective in the growth and design of cuprate-based hybrid structures.

Comparison of aortic valve repair techniques with single and double ring annuloplasties.

For patients with isolated aortic regurgitation, a double sub- and supravalvular annuloplasty has been shown to reduce recurrent aortic regurgitation after aortic valve repair compared with a single subvalvular annuloplasty. The objective of this study was to compare the geometrical and dynamic properties of a single- and double ring annuloplasty in an in vitro model. Eighteen aortic roots from 80 kg pigs were randomized into a control, single ring, and double ring group. Experiments were conducted in a pulsatile in vitro model. Hydrodynamics, radial force measurements at annular and sinotubular level, and 2D echographic imaging were obtained. Both the single- and double ring annuloplasty downsized the aortic annulus and sinotubular junction significantly, and increased the coaptation height. The double ring annuloplasty showed an additional significant increase in coaptation height compared with the single ring (8.5 (0.9) mm to 9.8 (0.8) mm, p < 0.01). The single ring annuloplasty reduced radial forces at both levels, whereas the double ring annuloplasty showed the greatest force reduction of the sinotubular junction. By treating the whole functional aortic annulus, encompassing both the aortic annulus and the sinotubular junction, a greater force reduction is observed. A subvalvular annuloplasty alone is efficient in reducing aortic annulus diameter and increasing coaptation height, however, by treating the sinotubular junction as well, an additional effect is observed on coaptation height, creating a more efficient stabilization. Reduction of annular force-distensibility ratio with the double ring annuloplasty compared with the native controls indicate a sustained stabilizing effect.

Using Mitral Annular Plane Systolic Excursion (MAPSE) and Tissue Doppler Imaging Systolic Velocity (TDIS’) As Surrogates of Left Ventricular Systolic Function

Purpose: Echocardiography has become a useful method for assessing structural diseases of the heart. MAPSE and TDI S’ have also been shown to be reproducible assessments of longitudinal heart changes as LVEF is ineffective in cases of sub-optimal echocardiographic imagery caused by artefacts or air trapping.&#x0D; Methodology: One hundred patients referred for echocardiography at the cardiac laboratory of DELSUTH, Oghara, Nigeria was recruited for the study. All patients had trans-thoracic echocardiography done with M-Mode, 2D and Spectral Doppler and Tissue Doppler echocardiographic images acquired. Data obtained was analyzed using IBM-SPSS version 22. A p-value of ≤0.05 was considered significant for all comparisons.&#x0D; Findings: Hypertension was the commonest indication for an echocardiogram. The prevalence of abnormal left ventricular function was 13%, 24% and 28% as determined using LVEF, TDI S’ and MAPSE. MAPSE had a higher specificity than TDI S’ with statistically significant correlations found between TDI S’ (p&lt;0.001); MAPSE (p=0.032) and LVEF. Multiple linear and binomial logistic regression analysis showed significant relationships (beta=0.423; p &lt;0.001) and odd ratios [OR(CI) = 10.80(2.56- 49.07)] respectively between TDI S’ and LVEF.&#x0D; Unique Contribution to Theory, Policy and Practice: MAPSE’s specificity allows for diagnosis of longitudinal heart functional changes even in cases where the LVEF may be within normal limits. A combination of both MAPSE and TDI S’ offer a greater prognostic significance. The correlation between MAPSE and TDI S’ were good. Thus, MAPSE and TDI S’ can serve as surrogates for LVEF in assessing left ventricular systolic function and prognosticating cardiac disease

СЛАБОЕ ГРАВИТАЦИОННОЕ ЛИНЗИРОВАНИЕ ЧЕРНЫМИ ДЫРАМИ С ЗАРЯДОМ

The deflection of light due to gravity was predicted by general relativity and first confirmed by observations in 1919. In the following decades, various aspects of the gravitational lensing effect were theoretically explored, including the possibility of obtaining multiple or annular images of background sources, the use of lensing as a gravitational telescope on very faint and distant objects, and the possibility of determining the Hubble constant using lensing. Gravitational lensing is the deflection of light by gravity caused by the action of compact astrophysical objects. Various objects, such as a galaxy, stars, black holes, wormholes, and others, can act as a gravitational lens. In our study, as a gravitational lens, we chose black holes described by the Gibbons-Maeda-GarfinkleHorowitz-Strominger solutions in the string frame. The two solutions in the string frame are magnetically and electrically charged black holes with an event horizon. The work will investigate the effect of electric and magnetic charges on the angle of deflection of light.

Panoramic annular image restoration algorithm by prediction based on the lens design characteristics.

A panoramic annular lens optical system is important in circumferential detection. However, a panoramic annular image (PAI) has severe tangential and radial distortion. This study proposes a 3σ guideline-based method, which determines the unwrapping center point of the PAI, and a prediction method based on the lens design characteristics according to the intrinsic distortion of the PAL to correct, respectively, the tangential distortion and the radial distortion. The proposed methods can ensure the restoration ability and simplify the dependence on experimental conditions. The experimental results confirm the effectiveness of the proposed method, thus enabling future panoramic optical image detection.

Predictive Value of Echocardiographic Pulmonary to Left Atrial Ratio for In-Hospital Death in Patients with COVID-19.

Echocardiographic Pulmonary to Left Atrial Ratio (ePLAR) represents an accurate and sensitive non-invasive tool to estimate the trans-pulmonary gradient. The prognostic value of ePLAR in hospitalized patients with COVID-19 remains unknown. We aimed to investigate the predictive value of ePLAR on in-hospital mortality in patients with COVID-19. One hundred consecutive patients admitted to two Italian institutions for COVID-19 undergoing early (&lt;24 h) echocardiographic examination were included; ePLAR was determined from the maximum tricuspid regurgitation continuous wave Doppler velocity (m/s) divided by the transmitral E-wave: septal mitral annular Doppler Tissue Imaging e'-wave ratio (TRVmax/E:e'). The primary outcome measure was in-hospital death. patients who died during hospitalization had at baseline a higher prevalence of tricuspid regurgitation, higher ePLAR, right-side pressures, lower Tricuspid Annular Plane Systolic Excursion (TAPSE)/ systolic Pulmonary Artery Pressure (sPAP) ratio and reduced inferior vena cava collapse than survivors. Patients with ePLAR &gt; 0.28 m/s at baseline showed non-significant but markedly increased in-hospital mortality compared to those having ePLAR ≤ 0.28 m/s (27% vs. 10.8%, p = 0.055). Multivariate Cox regression showed that an ePLAR &gt; 0.28 m/s was independently associated with an increased risk of death (HR 5.07, 95% CI 1.04-24.50, p = 0.043), particularly when associated with increased sPAP (p for interaction = 0.043). A high ePLAR value at baseline predicts in-hospital death in patients with COVID-19, especially in those with elevated pulmonary arterial pressure. These results support an early ePLAR assessment in patients admitted for COVID-19 to identify those at higher risk and potentially guide strategies of diagnosis and care.

614 PREDICTIVE ROLE OF ECHOCARDIOGRAPHIC PULMONARY TO LEFT ATRIAL RATIO FOR IN-HOSPITAL DEATH IN PATIENTS WITH COVID-19

Abstract Background and aims Echocardiographic Pulmonary to Left Atrial ratio (ePLAR, tricuspid regurgitation Vmax/mitral E/e') represents an accurate and sensitive non-invasive tool to estimate trans-pulmonary pressure gradient, showing a sensitivity for pre-capillary pulmonary obstruction higher than traditional echocardiographic measures. The prognostic value of ePLAR in patients with coronavirus disease-2019 (COVID-19) remains unknown. We aimed to investigate the predictive role of ePLAR on mortality in COVID-19 patients. Methods One hundred consecutive patients admitted in two Italian institutions for COVID-19 undergoing early echocardiographic examination were included. ePLAR was determined from the maximum tricuspid regurgitation velocity at continuous wave Doppler (m/s) divided by the transmitral E-wave: septal mitral annular Doppler Tissue Imaging e′-wave ratio (TRVmax/E:e′). Main outcome measure was in-hospital death. Results Patients who died during hospitalization had a higher prevalence of tricuspid regurgitation, higher ePLAR and right-side pressures, lower Tricuspid Annular Plane Systolic Excursion (TAPSE)/Pulmonary Artery Systolic Pressure (PASP) ratio and reduced inferior vena cava collapse than survivors. Patients with ePLAR &amp;gt;0.28 m/s showed increased in-hospital mortality compared to those having ePLAR ≤0.28 m/s (27% vs 10.8%, p=0.05, Figure). A Cox model of multivariate analysis demonstrated that an ePLAR &amp;gt;0.28 m/s was independently associated with increased risk of death (HR 5.07, 95% CI 1.04-24.50, p=0.043), particularly among patients with increased pulmonary arterial pressure. Conclusions A high ePLAR value at baseline predicts in-hospital death in patients with COVID-19, especially in those with elevated pulmonary arterial pressure. These results support an early ePLAR assessment in patients admitted for COVID-19 to identify those at higher risk and potentially to guide strategies of diagnosis and treatment.

Experimental reconstructions of 3D atomic structures from electron microscopy images using a Bayesian genetic algorithm

We introduce a Bayesian genetic algorithm for reconstructing atomic models of monotype crystalline nanoparticles from a single projection using Z-contrast imaging. The number of atoms in a projected atomic column obtained from annular dark field scanning transmission electron microscopy images serves as an input for the initial three-dimensional model. The algorithm minimizes the energy of the structure while utilizing a priori information about the finite precision of the atom-counting results and neighbor-mass relations. The results show promising prospects for obtaining reliable reconstructions of beam-sensitive nanoparticles during dynamical processes from images acquired with sufficiently low incident electron doses.

Optical incoherent imaging using annular synthetic aperture with the superposition of phase-shifted optical transfer functions

The optical incoherent synthetic aperture (SA) has wide applications in astronomy and biomedical optics. Super-resolution imaging can be achieved through SAs with an effective size several times larger than the size of the physical apertures. In this Letter, we propose a new, to the best of our knowledge, method to realize optical incoherent SA imaging. Instead of scanning the entire area of the full SA, we show that similar imaging performance can be achieved by scanning only along its perimeter. At any given time, only a single pair of sub-apertures located at the SA perimeter is open and reflects the incident light toward an image sensor. For each location of the two sub-apertures, two interfering images are captured. The phase difference between the two sub-apertures is zero for one interfering image and π for the other. The image of the object is reconstructed by superposition of all the interfering images from some of the sub-aperture locations and with the two-phase differences, 0 and π, between the two sub-apertures. Optical experiments have been performed using reflective objects, and the results demonstrate similar imaging capabilities as that of direct imaging with the aperture size of the SA. Furthermore, we have compared the proposed SA imaging results with the results of annular and full aperture direct imaging.

Fabrication and Excellent Performances of Bismuth Telluride-Based Thermoelectric Devices.

The barrier layer between thermoelectric (TE) legs and electrodes has crucial impact on the electrothermal conversion efficiency of the TE device; however, the interfacial reaction of the Ni metal barrier layer with TE legs in traditional Bi2Te3-based devices is harmful to the device performance. Herein, a high-quality barrier layer of a Ni-based alloy has been fabricated on both n-type and p-type Bi2Te3-based TE legs by the electroplating method. The in situ XRD results indicate that the as-prepared Bi2Te3-based TE legs with a Ni-based alloy barrier layer remain stable even at 300 °C. The high-resolution high-angle annular dark field scanning transmission electron microscopy images reveal that the Ni-based alloy barrier layer has more excellent stability than that of the Ni metal barrier layer. The Bi2Te3-based TE devices with excellent structural and performance stabilities were assembled with the as-grown high-performance n-type and p-type Bi2Te3-based leg with a Ni-based alloy barrier layer, which have lower internal resistance and higher cooling and power generation performances. A maximum cooling temperature difference over 65 K and a maximum cooling capacity of 55 W were obtained for the high-performance Bi2Te3-based TE devices. This work provides a new strategy for high-temperature applications of commercial Bi2Te3-based TE devices.