Proximity Region Research Articles

Complex coincidence of superconducting and inverse proximity in quasi 2D nanostructured SnTe

The induction of superconductivity in topological insulators and topological crystalline insulators is being investigated rigorously as a promising strategy for taking quantum spintronic applications to the next level. In this work, the complex interplay between topological and superconducting components is carefully tuned in such a way that an unusual coincidence of superconducting and inverse proximity is captured for the first time in the electrical transport properties of quasi two-dimensional nanostructured SnTe contacted using ‘s-wave’ superconducting electrodes. Ultralow temperature measurements in the complex superconducting proximity phase reveal two critical fields (H c2) of 0.9 T and 510 Oe. The lower H c2 is identified to be from the superconducting electrode while the higher one is attributed to the interface. The presence (absence) of coincidence between the upper critical field (H C2) extracted from Ginzburg–Landau theory and the Werthamer–Helfand–Hohenberg plot in the normal (inverse) superconducting proximity region and concurrent crossover in correlation lengths ξ(T) and L φ(T) are observed to be the manifestation of robust competition between the mutual domination of different mechanisms such as topological surface states and Cooper pair correlations. The current-dependent magnetoresistance measurements clearly demonstrate the dominant role of the interplay between the superconducting correlations and spin–orbit coupling. Interestingly, mere doubling of the contact area of the superconductor is observed to simultaneously enhance the critical field to ∼4 T and the transition temperature to ∼4.1 K in the interface region, suggesting the possibility of opening up a new gateway into nano-topological superconducting spintronic applications.

Novel Modal Resonance Proximity Region between photovoltaic and multi‐machine subsystems under inertia and damping variations

AbstractA Modal Resonance Proximity Region (MRPR) is proposed is to analyse dynamic interactions between photovoltaic (PV) converters and synchronous generators in a multi‐machine system. The MRPR, delimited by the intersection of open‐loop modes' possible positions from two subsystems, indicates that two open‐loop modes would encounter each other in this region and modal resonances occur. Also, an indicator is utilised to assess the strength of such dynamic interaction. On top of MRPR and indicator, PV control parameters are optimised to avoid the possibly occurring modal resonances. As shown in time‐domain simulation, the proposed MRPR can precisely capture the occurring region for potential modal resonances and such potential modal resonances can be significantly mitigated by the MRPR and indicator‐based PV control parameter optimisation.

A Cone Beam Computed Tomography Analysis of Bone Volume Variations of Extra-alveolar Region Based on Sex, Age, Vertical and Sagittal Facial Patterns.

The goal of this study is to measure mandibular buccal shelf (MBS) concerning angulation, bone volume, and cortical bone volume as well as bone depth and cortical bone depth of infrazygomatic crest (IZC) via cone beam computed tomography and evaluate the measurements according to sex, age, vertical, and sagittal facial types. This study collected lateral cephalograms and cone beam computed tomography scans from 100 individuals, which were used to observe angulation, bone and cortical bone volume entailing width and depth of MBS as well as the depth of IZC. FH-MP (mandibular plane angle) and A point-Nasion-B point were adopted to determine vertical and sagittal facial patterns respectively. Bone widths at 6mm and 11mm to cementoenamel junction (CEJ) and cortical bone width at 6mm to CEJ in MBS showed significant sex differences, while bone depths and cortical bone depths in IZC show significant age difference( P <0.05). Bone width and cortical bone width at 6mm to CEJ at the mesial root and 11mm to CEJ at both roots as well as angulations of MBS in the mandibular first molar region, bone depth and cortical bone depth at the maxillary first molar distal buccal root, and the proximity region were all correlated to FH-MP ( P <0.05). Short-faced individuals of Asian ethnicity tend to have greater bone width, greater projection in MBS, and greater bone depth in the posterior region of IZC. The optimal implant sites are 11mm apical to CEJ at the mandibular second molar distal root and 65° at the maxillary first molar mesial root.

Superconductivity at Interfaces in Cuprate-Manganite Superlattices.

One of the unsolved problems for using high-Tc superconducting cuprates for spintronic applications are the short coherence lengths of Cooper pairs in oxides (a few Å), which requires atomically sharp and defect-free interfaces. This research demonstrates the presence of high-Tc superconducting La1.84 Sr0.16 CuO4 in direct proximity to SrLaMnO4 and provides evidence for the sharpness of interfaces between the cuprate and the manganite layers at the atomic scale. These findings shed light on the impact of the chemical potential at the interface of distinct materials on highly sensitive physical properties, such as superconductivity. Additionally, this results show the high stability of ultrathin layers from the same K2 NiF4 -type family, specifically one unit cell of Sr2- x Lax MnO4 and three unit cells of La1.84 Sr0.16 CuO4 . This work advances both the fundamental understanding of the proximity region between superconducting cuprates and manganite phases and the potential use of oxide-based materials in quantum computing.

Fresh data collection for UAV-assisted IoTs based on proximity-remote region collaboration

Unmanned Aerial Vehicles (UAVs) can assist Internet of Things (IoT) systems in collecting data from sensor nodes due to their high flexibility and ease of deployment. However, in existing UAV-assisted IoTs, there is neither mission overlap nor mission collaboration between UAVs, which requires all UAVs to return to the base station to offload the collected data. This results in significant latency in data transmission. Therefore, we propose a proximity-remote region collaborative data collection scheme to overcome this problem. In this scheme, we first divide the mission region into the proximity region and the remote region, and deploy an appropriate ratio of UAVs in each region for data collection. Second, we balance the flight paths of UAVs in different regions by updating the partition. Finally, we achieve seamless relay transmission between UAVs by selecting relay points, modifying UAV flight paths, and adjusting flight speed and take-off points. Through the above process, data collected from the remote region can rapidly reach the base station through seamless collaborative relays between UAVs. Extensive experimental results have shown that the proposed scheme can effectively reduce the data transmission latency of the system compared to existing data collection schemes.

Experimental and numerical investigation of residual stresses in proximity girth welds

International fabrication codes and standards provide minimum distance criteria for proximity welds, although rigorous justification is lacking. These distances are either based on practical experience or mutual agreement and are often left to the engineering judgment of contractors, inspection engineers, etc., especially in cases of repair welds fabricated in proximity to existing welds. Previous studies have shown high tensile residual stresses and altered mechanical and microstructural properties between proximity welds. This article focuses on numerical and experimental quantification of residual stresses in the proximity region by X-ray diffraction (XRD) and finite element method (FEM) thermo-mechanical models. Specimens were machine welded, then repair welded at distances of 5–15 mm. A fair agreement in results was achieved between FEM and XRD. The most detrimental effect was observed at the weld root toe for the repair weld at 5 mm proximity, likely due to the high constraint and multiaxial stress state. These findings enable practitioners to propose technical justification and corrective actions while specifying minimum distance criteria for proximity welds.

Predictive value of magnetoencephalography in guiding the intracranial implant strategy for intractable epilepsy.

Magnetoencephalography (MEG) is a useful component of the presurgical evaluation of patients with epilepsy. Due to its high spatiotemporal resolution, MEG often provides additional information to the clinician when forming hypotheses about the epileptogenic zone (EZ). Because of the increasing utilization of stereo-electroencephalography (sEEG), MEG clusters are used to guide sEEG electrode targeting with increasing frequency. However, there are no predefined features of an MEG cluster that predict ictal activity. This study aims to determine which MEG cluster characteristics are predictive of the EZ. The authors retrospectively analyzed all patients who had an MEG study (2017-2021) and underwent subsequent sEEG evaluation. MEG dipoles and sEEG electrodes were reconstructed in the same coordinate space to calculate overlap among individual contacts on electrodes and MEG clusters. MEG cluster features-including number of dipoles, proximity, angle, density, magnitude, confidence parameters, and brain region-were used to predict ictal activity in sEEG. Logistic regression was used to identify important cluster features and to train a binary classifier to predict ictal activity. Across 40 included patients, 196 electrodes (42.2%) sampled MEG clusters. Electrodes that sampled MEG clusters had higher rates of ictal and interictal activity than those that did not sample MEG clusters (ictal 68.4% vs 39.8%, p < 0.001; interictal 71.9% vs 44.6%, p < 0.001). Logistic regression revealed that the number of dipoles (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.04-1.14, t = 3.43) and confidence volume (OR 0.02, 95% CI 0.00-0.86, t = -2.032) were predictive of ictal activity. This model was predictive of ictal activity with 77.3% accuracy (sensitivity = 80%, specificity = 74%, C-statistic = 0.81). Using only the number of dipoles had a predictive accuracy of 75%, whereas a threshold between 14 and 17 dipoles in a cluster detected ictal activity with 75.9%-85.2% sensitivity. MEG clusters with approximately 14 or more dipoles are strong predictors of ictal activity and may be useful in the preoperative planning of sEEG implantation.

A potent PGK1 antagonist reveals PGK1 regulates the production of IL-1β and IL-6.

Glycolytic metabolism enzymes have been implicated in the immunometabolism field through changes in metabolic status. PGK1 is a catalytic enzyme in the glycolytic pathway. Here, we set up a high-throughput screen platform to identify PGK1 inhibitors. DC-PGKI is an ATP-competitive inhibitor of PGK1 with an affinity of K d=99.08nmol/L. DC-PGKI stabilizes PGK1 invitro and invivo, and suppresses both glycolytic activity and the kinase function of PGK1. In addition, DC-PGKI unveils that PGK1 regulates production of IL-1β and IL-6 in LPS-stimulated macrophages. Mechanistically, inhibition of PGK1 with DC-PGKI results in NRF2 (nuclear factor-erythroid factor 2-related factor 2, NFE2L2) accumulation, then NRF2 translocates to the nucleus and binds to the proximity region of Il-1β and Il-6 genes, and inhibits LPS-induced expression of these genes. DC-PGKI ameliorates colitis in the dextran sulfate sodium (DSS)-induced colitis mouse model. These data support PGK1 as a regulator of macrophages and suggest potential utility of PGK1 inhibitors in the treatment of inflammatory bowel disease.

Experimental investigation of residual stress distribution on girth welds fabricated at proximity using neutron diffraction technique

Maintaining minimum distance between repair and existing welds often becomes impractical due to the presence of compact layouts, original welds of branches, nozzles, etc. on offshore structural elements, pipelines, and piping. Although some international codes and standards provide criteria for maintaining a minimum distance between proximity welds, most of them lack technical justification in relation to their effect on the structural integrity of welded components. The development of residual stresses has a significant effect (i.e., a negative effect on tensile stresses and a positive effect on compressive stresses) on the integrity of the welds fabricated at proximity. Hence, it is important to investigate the residual stress distribution on welds fabricated at proximity, especially at a distance away from the weld toe. This study presents findings on the characterization of residual stresses by neutron diffraction at the proximity region between two girth welds. The two welds were fabricated at proximity, using two different welding procedure specifications and at three different distances, on a structural steel pipe, grade S355. The three different welding distances between weld toes were maintained at 5, 10, and 15 mm respectively. The neutron diffraction-based residual stress distributions were investigated at the POLDI neutron instrument at the Swiss spallation source SINQ in Switzerland. The axial, hoop, and radial components of the residual stresses were experimentally investigated between proximity welds. The findings revealed that residual axial stresses at a 5-mm proximity distance were increased beyond the yield strength of the structural steel, grade S355. The findings of this study enable practitioners to take remedial actions to minimize the residual stresses developed in girth welds fabricated at proximity. Also, the findings enable us to derive technical justification for maintaining a minimum distance and developing welding procedure for welds fabricated at proximity.

Welding procedure qualification record (WPQR) for welds fabricated at proximity

Maintaining the minimum allowable distance between proximity welds has always been considered a subject of debate among design engineers, welding engineers/inspectors and fabricators/engineering contractors. The scattered nature of guidelines available in welding codes and standards for maintaining the minimum allowable distance poses a significant challenge in the welding procedure and inspection criteria development process. This is especially critical for complex welded joints on submerged sections of offshore structures, in compact layouts/branched connections of topside piping components, and on topside structural joints (depending on the complexity). This manuscript presents the findings of an experimental study that was performed by fabricating two girth welds at proximity on an S355 steel tubular section with diameter of 219.1 mm and thickness of 8.18 mm. Proximity girth welds were fabricated on S355 tubular sections at three different distances between their weld toes, 5, 10, and 15 mm, respectively, using two different welding procedures. Welding procedure qualification record (WPQR) was performed, and all prescribed mechanical tests were recorded as per NORSOK M-101, a structural steel fabrication code. Although all results from the mechanical test met the minimum specified values as defined in the NORSOK code, the research findings revealed a noticeable difference in Charpy and hardness values for proximity region between adjacent welds. Considerable changes in final microstructure morphology were observed between proximity welds due to varying thermal cycles. These observations can form the basis for the future welding procedure qualification of critical welded joints, especially for proximity welds on critical welded joints of offshore structures and welds fabricated during replacement/repair procedures in compact piping layouts.

Charge-neutral nonlocal response in superconductor-InAs nanowire hybrid devices

Nonlocal quasiparticle transport in normal-superconductor-normal (NSN) hybrid structures probes sub-gap states in the proximity region and is especially attractive in the context of Majorana research. Conductance measurement provides only partial information about nonlocal response composed from both electron-like and hole-like quasiparticle excitations. In this work, we show how a nonlocal shot noise measurement delivers a missing puzzle piece in NSN InAs nanowire-based devices. We demonstrate that in a trivial superconducting phase quasiparticle response is practically charge-neutral, dominated by the heat transport component with a thermal conductance being on the order of conductance quantum. This is qualitatively explained by numerous Andreev reflections of a diffusing quasiparticle, that makes its charge completely uncertain. Consistently, strong fluctuations and sign reversal are observed in the sub-gap nonlocal conductance, including occasional Andreev rectification signals. Our results prove conductance and noise as complementary measurements to characterize quasiparticle transport in superconducting proximity devices.

Competition between perceptual grouping cues in an indirect objective task

The integration between Gestalt grouping cues has been a relatively unexplored issue in vision science. The present work introduces an objective indirect method based on the repetition discrimination task to determine the rules that govern the dominance dynamics of the competition between both intrinsic (Experiment 1: proximity vs luminance similarity) and extrinsic grouping cues (Experiment 2: common region vs connectedness) by means of objective measures of grouping (reaction times and accuracy). Prior to the main task, a novel objective equating task was introduced with the aim of equating the grouping strength of the cues for the visuomotor system. The main task included two single conditions with the grouping cues acting alone as well as two competing conditions displaying the grouping factors pitted against one another. Conventional aggregated analyses were combined with individual analysis and both revealed a consistent pattern of processing dominance of: (1) luminance similarity over proximity and (2) common region over connectedness. Interestingly, the individual analyses showed that, despite the heterogeneous responses to the single conditions, the pattern of dominance between cues was robustly homogeneous among the participants in the competing conditions.

Numerical investigation of inertial sphere impaction on a cylinder in subcritical flow

This study examined the accuracy of a Lagrangian scheme for simulating both the motion and wall impaction of neutrally buoyant inertial spheres (8.85 St 18.04) moving in the subcritical regime (Re = 10,972 and 22,366) of flows past a circular cylinder. The accuracy of the eddy-resolving simulations of the flow field was verified based on available data at nearly comparable flow conditions. The accuracy of the particle tracking scheme was verified with respect to corresponding experimental data in a laboratory flume. Particle dispersion en route to the circular cylinder is mostly driven by the flow disturbance from the particle injector tube. The trends in collision rates are largely explained by the rate of particle entertainment into the boundary layer around the cylinder and the inertial condition of the spheres in this proximity region—both of which can be better assessed by post-processing of the numerical outcomes. The primary incentive to undertake this work was the need for validating a particle-based method for quantifying the hydraulic stressors leading to bodily damage of fish passing flows influenced by hydraulic infrastructure.

Rapid and Large‐Scale Fabrication of Full Color Woodpile Photonic Crystals via Interference from a Conformal Multilevel Phase Mask

AbstractThe practical use of photonic crystals with structural colors requires technology capable of rapidly producing large‐area, three‐dimensional (3D) periodic nanostructures. Until now, the fabrication of 3D photonic crystals has relied mainly on additive manufacturing and colloidal self‐assembly. These technologies have provided a useful academic platform based on precisely controlled 3D periodicity but have not evolved into mass production technology. Here, optical lithography for the rapid fabrication of large‐area 3D photonic crystals with structural colors is introduced. The key strategy is to incorporate two orthogonal line gratings (periodicity: 300 nm) made of an elastomer to create a conformal multilevel phase mask. When the mask is irradiated with a 355 nm laser, the five beam interference is established in the proximity region. The interlayer thickness between the two orthogonal line gratings controls the phase difference, which is closely related to the symmetry of the resulting 3D interference pattern. The interlayer thickness is designed to produce a woodpile structure with a planar periodicity of 300 nm and a vertical periodicity of 716 nm. The pattern area of the woodpile photonic crystal is expanded to 1 in2. Red, green, and blue colors are experimentally realized by controlling the vertical shrinkage of the photoresist.

Expansion of a superconducting vortex core into a diffusive metal

Vortices in quantum condensates exist owing to a macroscopic phase coherence. Here we show, both experimentally and theoretically, that a quantum vortex with a well-defined core can exist in a rather thick normal metal, proximized with a superconductor. Using scanning tunneling spectroscopy we reveal a proximity vortex lattice at the surface of 50 nm—thick Cu-layer deposited on Nb. We demonstrate that these vortices have regular round cores in the centers of which the proximity minigap vanishes. The cores are found to be significantly larger than the Abrikosov vortex cores in Nb, which is related to the effective coherence length in the proximity region. We develop a theoretical approach that provides a fully self-consistent picture of the evolution of the vortex with the distance from Cu/Nb interface, the interface impedance, applied magnetic field, and temperature. Our work opens a way for the accurate tuning of the superconducting properties of quantum hybrids.

Transverse and Longitudinal proximity effect

With close pairs (1.5arcmin) of quasars (QSOs), absorption in the spectra of a background quasar in the vicinity of a foreground quasar can be used to study the environment of the latter quasar at kpc-Mpc scales. For this we used a sample of 205 quasar pairs from the Sloan Digital Sky-Survey Data Release 12 (SDSS DR12) in the redshift range of 2.5 to 3.5 by studying their H I Ly-α absorption. We study the environment of QSOs both in the longitudinal as well as in the transverse direction by carrying out a statistical comparison of the Ly-α absorption lines in the quasar vicinity to that of the absorption lines caused by the inter-galactic medium (IGM). This comparison was done with IGM, matched in absorption redshift and signal-to-noise ratio (SNR) to that of the proximity region. In contrast to the measurements along the line-of-sight, the regions transverse to the quasars exhibit enhanced H I Ly-α absorption. This discrepancy can either be interpreted as due to an anisotropic emission from the quasars or as a consequence of their finite lifetime.

Bounds to the normal for proximity region graphs

In a proximity region graph G in Rd, two distinct points x,y of a point process μ are connected when the ‘forbidden region’ S(x,y) these points determine has empty intersection with μ. The Gabriel graph, where S(x,y) is the open disk with diameter the line segment connecting x and y, is one canonical example. When μ is a Poisson or binomial process, under broad conditions on the regions S(x,y), bounds on the Kolmogorov and Wasserstein distances to the normal are produced for functionals of G, including the total number of edges and the total length. Variance lower bounds, not requiring strong stabilization, are also proven to hold for a class of such functionals.

Photonic Bell-state analysis based on semiconductor-superconductor structures

We propose a compact and highly efficient scheme for complete Bell-state analysis using two-photon absorption in a superconducting proximity region of a semiconductor avalanche photodiode. One-photon transitions to the superconducting Cooper-pair based condensate in the conduction band are forbidden, whereas two-photon transitions are allowed and are strongly enhanced by superconductivity. This Cooper-pair based two-photon absorption results in a strong detection preference of a specified entangled state. Our analysis shows high detection purity of the desired Bell state with negligible false detection probability. The theoretically demonstrated concept can pave the way towards practical realizations of advanced quantum information schemes.

Similarity grouping as feature-based selection

Our visual system groups objects with similar features, such as colour, orientation, or shape. We argue that similarity grouping is nothing more than global selection of a certain feature value, such as red, horizontal, or circular. This account makes the striking prediction that only one feature group can be created at a time. Here we provide the most direct evidence yet for this proposal, using a number estimation task that forces simultaneous processing of all objects. Multiple similarity cues failed to produce grouping in this task, in contrast to proximity, connectivity, and common region, which all showed strong grouping effects.

Surface textures on cemented carbide cutting tools by micro EDM assisted with high-frequency vibration

This paper demonstrates the process of micro electro-discharge machining (micro EDM) assisted with high-frequency vibration machining micro holes and linear grooves which are straight or inclined on WC/8 % Co (MA) and WC/15 % TiC/6 %Co (MB) cemented carbide cutting tool rake face or scrap reeling slot. Low-voltage sensing contact is introduced to determine the exact position of holes and grooves. Morphology of textured regions is examined and the elemental chemical composition of close proximity region to a straight hole is identified. Results show that micro holes and linear grooves with high dimension accuracy and exact position are machined as expected by micro EDM assisted with high-frequency vibration. There is no debris accumulating around the cavities. Materials of MA cutting tool adhere on the micro tool electrode slightly, while the dimension of adhesion position becomes constant after 3 μ holes are finished. However, the adhesion does not occur during machining MB cutting tools. The distance of edges of grain refinement regions and areas where elemental chemical composition varies to the contour of the hole is no more than 15 μm.