Normal Layer Research Articles

Influence of enzyme and probiotic supplementation on growth performance and gut health of broiler chicken

This study was carried out to investigate the effects of enzyme, probiotic or their combinations on growth response, microbiota and gut histopathological indices of broiler chicken. One hundred and fifty (150) one-day old unsexed Arbor Acre broiler chicks were weighed and randomly allotted to 5 dietary treatments; each diet had 5 replicates of 6 birds each in the study that lasted for 42 days. Treatment 1 consists of the basal diet (negative control; NC): Treatment 2 was NC+0.1% antibiotic (positive control), Treatment 3: NC+0.4% probiotic, Treatment 4: NC+0.1% enzyme and Treatment 5: NC+0.4% probiotic+0.1% enzyme. Performance indices were measured. On day 42, ileal digesta was collected from two birds per replicate for microbial count while about 5 cm of distal ileum was severed for histopathology. The results showed that diets had no significant (p>0.05) effect on the performance of birds at the starter and finisher phases. Total heterotrophic counts of birds fed with basal and probiotic diets were similar but significantly (p<0.05) higher than other diets. The highest Lactobacilli count was recorded in the mixture of probiotic + enzyme diet while least was observed in probiotic (2.58×105 cfu/ml) and enzyme supplemented diets (1.45×105 cfu/ml). Total coliform count of birds fed antibiotic diet was significantly (p<0.05) lower (14.12×105 cfu/ml) than for those on other diets. Total Escherichia coli count was highest in birds fed antibiotic while least was observed in birds fed mixture of probiotics + enzyme diet. Photomicrographs of the ileum of birds fed basal diet showed sloughed mucosa layer and degenerated villi. However birds fed antibiotic, probiotic, enzyme or probiotic+enzyme diets showed normal mucosa layer with normal villi, the lamina proprial showed normal tissues with mild infiltrate. In conclusion, feed supplements used in this study can serve as viable alternatives to antibiotics in broiler nutrition without compromising birds’ health

Fabrication of GaN cantilever on GaN substrate by photo-electrochemical etching

Photo-electrochemical (PEC) etching is a promising technique for fabricating GaN microelectromechanical systems devices. In this study, we demonstrate the fabrication of GaN cantilevers by the bandgap-selective PEC etching of an InGaN superlattice sacrificial layer. By using an InGaN superlattice as a sacrifice layer, we found the PEC etching rate became higher than using a normal InGaN layer. As a result, the InGaN superlattice was completely etched and we fabricated GaN-based cantilevers whose resonance characteristics were measured. The Young’s modulus of GaN was determined from the resonance characteristics of GaN cantilevers to be the same as the highest value reported previously.

A local rapid temperature rise model for analyzing the effects of irradiation on human skin in laser treatments

In laser treatments, the difference in patient's degree of skin pigmentation is an important factor that can lead to medical accidents. However, the conventional heat transfer model is not available to analyze the effect of degree of pigmentation on the laser treatments. Therefore, we propose a new microscopic radiation heat transfer model that takes into account the point heat sources for the laser treatments. In the proposed model, skin considered as a bulk medium consisting of two layers, namely normal and pigmentation layers with the latter containing a larger number of melanosomes having a specific volume fraction (fv,mel) as the degree of pigmentation. Using the proposed model, it was found that the distribution of the absorbed laser energy and temperature rise of the skin tissue is affected by the degree of pigmentation. When fv,mel is high, the absorbed energy per single melanosome and thus the temperature rise of the pigmentation layer is lower than that in the deeper skin tissue. It was also shown that depending on fv,mel, the distance between melanosomes decreases. When fv,mel is high, the temperature of skin tissue between melanosomes increases.

Development of a New Type of Geodiversity System for the Scoria Cones of the Chaîne des Puys Based on Geomorphometric Studies

The aesthetic beauty of a landscape is an integral value reflected in artistic inspiration. Science, in contrast, tries to quantify the landscape using various methods. Of these, geodiversity indices have been found to be a useful approach, and this geomorphological diversity is characterized through derivatives made from digital terrain models (DTM). While these methods are useful, they have a drawback that the value of some landscape features may be underestimated if they have regular forms. For example, the aesthetic and scientific attractiveness of our study area, the Chaîne des Puys (Auvergne, France), a UNESCO World Heritage site, is strongly related to the distinctive small volcanoes, but despite being an outstanding element of the landscape, the scoria cones do not stand out well in geodiversity indices. This is because they have almost symmetrical conical forms and regular slopes that score low in the available geodiversity methods. We explore this problem and investigate how to overcome the low geodiversity performance of these distinctive landscape elements. We propose a modified approach for scoria cones using the normal input layers but adapted to the cone geometry. The modified indices are easy to compute and consider the uniformity and symmetry of larger landscape elements that form scientifically integral and aesthetically vital components of the landscape. The method is applicable to the tens of thousands of small monogenetic volcanoes in the hundreds of volcanic fields around the world, and could be extended to other volcanic features, such as domes. It would be possible to use the method to study larger volcanoes, as they often share and replicate the small-scale monogenetic morphology considered here.

A general process model for unanticipated state recognition of a telescope drive system

Abstract This paper presents a three-layer general process model for unanticipated state recognition in a telescope drive system, consisting of an anticipated fault diagnosis layer, an unanticipated normal state isolation layer, and an unanticipated fault state recognition layer. It is proposed for the first time to subdivide the unanticipated state into an unanticipated normal state and an unanticipated fault state in this paper, and to study their theories separately. Unanticipated normal state isolation rules based on angle deviation and amplitude deviation are established, as are unanticipated fault state recognition rules based on angle deviation and deviation contribution factor. Finally, normal operation data of the Antarctic Survey Telescope (AST3-3) combined with fault implantation was used to verify the validity of the model. The results show that the method can effectively carry out isolation of the unanticipated normal state and identification of the unanticipated fault state.

Optic nerve head melanocytoma: Optical coherence tomography/angiography features.

Purpose:The objective of this study was to identify the diagnostic features of optic nerve head melanocytoma (ONH-MCT) on spectral domain optical coherence tomography (SD OCT) and OCT angiography (OCT-A).Methods:Retrospective study of 11 patients for their demographic, clinical features and imaging including SD OCT (tumour location, extent and interface) and OCT-A (surface and intrinsic vascularity) were reviewed. Flow rate percentage (FR %) was calculated over the lesion and compared to fellow eye and similar pigmented lesions.Results:The average age was 52.8 ± 10.9 years. ONH-MCT tumors occupied 3-tissue spaces- optic disc (n = 2), retinal layer (n = 5) and retina-choroidal layers (n = 4). SD OCT (11 eyes) showed elevated hyper reflective disorganized retinal layers with posterior shadowing (9 eyes) and hyper reflective dots within the tumor (all eyes). Microvascular features on OCT-A (8 eyes) in radial peripapillary capillary slab showed surface vascularization (7 eyes) and intrinsic vascularity in choroidal slab (8 eyes) with surrounding hypo reflective boundary. The mean FR % was higher at 65.1 ± 3.77% (CI: 61.9-68.2) compared to mean FR at 60.4 ± 1.06% (CI: 59.5-61.2) in the fellow eye (p = 0.01). Comparison with nevus and melanoma SD OCT showed a high reflective choroidal layer with normal or irregular outer retinal layers respectively; OCT-A showed hypo reflective area at the center with hyper reflective boundary and iso reflective area at center with hyper reflective boundary respectively.Conclusion:SD OCT and OCT-A features may help to differentiate ONH-MCT from clinically similar looking pigmented lesions like nevus and melanoma.

Acousto- and acousto-optic effects in liquid crystals: An overview

An overview of the following three aspects of the acoustical and related optical behavior of liquid crystals, namely i) ultrasonic studies, ii) acousto-optical effects, and iii) surface wave induced optical effects have been discussed. The temperature dependent ultrasound velocity has been used for the evaluation of the adiabatic compressibility (kS) and the acoustic impedance (Z). A correlation between thermodynamic functions and thermo-elastic properties facilitated the evaluation of the specific heat at constant volume (CV), the ratio of specific heats (g) and the isothermal compressibility (kT) across liquid crystal-isotropic phase transition. Acousto-optical effect in liquid crystals has been described in terms of molecular reorientation related to flows and turbulences due to acoustic vibration and radiation pressure in the medium. One important aspect of the acousto-optical effects is the surface wave induced optical effects. The change in transparency of a normal layer of liquid crystal under crossed polarizers are discussed which is interpreted as a consequence of the rotation of the optic axis. In addition, the acoustic emission occurring from homeotropically-aligned liquid crystals irradiated by surface acoustic waves are also discussed.

Supercurrent Induced by Chiral Coupling in Multiferroic/Superconductor Nanostructures.

We study the transport and the superconducting dynamics in a layer of type II superconductor (SC) with a normal top layer that hosts a helical magnetic ordering that gives rise to spin-current-driven ferroelectric polarization. Proximity effects akin to this heterostructure result in an anisotropic supercurrent transport and modify the dynamic properties of vortices in the SC. The vortices can be acted upon and controlled by electric gating or other means that couple to the spin ordering in the top layer, which, in turn, alter the superconducting/helical magnet coupling characteristics. We demonstrate, using the time dependent Ginzburg–Landau approach, how the spin helicity of the top layer can be utilized for pinning and guiding the vortices in the superconducting layer.

Mycobacterium tuberculosis Cells Surviving in the Continued Presence of Bactericidal Concentrations of Rifampicin in vitro Develop Negatively Charged Thickened Capsular Outer Layer That Restricts Permeability to the Antibiotic.

Majority of the cells in the bacterial populations exposed to lethal concentrations of antibiotics for prolonged duration succumbs to the antibiotics’ sterilizing activity. The remaining cells survive by diverse mechanisms that include reduced permeability of the antibiotics. However, in the cells surviving in the continued presence of lethal concentrations of antibiotics, it is not known whether any cell surface alterations occur that in turn may reduce permeability of the antibiotics. Here we report the presence of a highly negatively charged, hydrophilic, thickened capsular outer layer (TCOL) on a small proportion of the rifampicin surviving population (RSP) of Mycobacterium tuberculosis (Mtb) cells upon prolonged continuous exposure to bactericidal concentrations of rifampicin in vitro. The TCOL reduced the intracellular entry of 5-carboxyfluorescein-rifampicin (5-FAM-rifampicin), a fluorochrome-conjugated rifampicin permeability probe of negligible bacteriocidal activity but comparable properties. Gentle mechanical removal of the TCOL enabled significant increase in the 5-FAM-rifampicin permeability. Zeta potential measurements of the cells’ surface charge and hexadecane assay for cell surface hydrophobicity showed that the TCOL imparted high negative charge and polar nature to the cells’ surface. Flow cytometry using the MLP and RSP cells, stained with calcofluor white, which specifically binds glucose/mannose units in β (1 → 4) or β (1 → 3) linkages, revealed the presence of lower content of polysaccharides containing such residues in the TCOL. GC-MS analyses of the TCOL and the normal capsular outer layer (NCOL) of MLP cells showed elevated levels of α-D-glucopyranoside, mannose, arabinose, galactose, and their derivatives in the TCOL, indicating the presence of high content of polysaccharides with these residues. We hypothesize that the significantly high thickness and the elevated negative charge of the TCOL might have functioned as a physical barrier restricting the permeability of the relatively non-polar rifampicin. This might have reduced intracellular rifampicin concentration enabling the cells’ survival in the continued presence of high doses of rifampicin. In the context of our earlier report on the de novo emergence of rifampicin-resistant genetic mutants of Mtb from the population surviving under lethal doses of the antibiotic, the present findings attain clinical significance if a subpopulation of the tubercle bacilli in tuberculosis patients possesses TCOL.

Analysis of flow-field in a dual mode ramjet combustor with boundary layer bleed in isolator

A two-dimensional Reynolds averaged Navier Stokes (RANS) simulation of a dual mode ramjet (DMRJ) combustor is performed, modeling the University of Michigan dual-mode combustor experimental setup operating in reacting mode with different equivalence ratios (φ). The simulations are carried out using a k-ω SST turbulence model and a steady diffusion flamelet model for non-premixed combustion. Air enters the isolator at Mach 2.2, stagnation pressure and temperature of 549.2 kPa and 1400 K respectively. Hydrogen is injected transverse to the flow direction and upstream of the cavity flame holder to simulate ramjet (φ = 0.29) and scramjet (φ = 0.19) modes of operation. Wall static pressure plots are used to validate numerical results against experimental data. Analysis of flow separation in ramjet mode due to the presence of a shock train in the isolator is carried out by means of numerical Schlieren images overlapped with contours of negative axial velocity, showing the effects of shock wave boundary layer interaction (SWBLI). Active control through wall normal boundary layer bleed in the separated flow region is implemented, which weakens the shock train and moves it downstream closer to the cavity. Bleed results in an improved stagnation pressure recovery in ramjet mode, with a marginal increase in combustion efficiency.

Large enhancement of spin pumping due to the surface bound states in normal metal–superconductor structures

We show that the spin pumping from ferromagnetic insulator into the adjacent metallic spin sink can be strongly stimulated by the superconducting correlations. The key physical mechanism responsible for this effect is the presence of quasiparticle surface states at the ferromagnetic insulator/superconductor interface. We consider the minimal model when these states appear because of the suppressed pairing constant within the interfacial normal layer. For thin normal layers we obtain a strongly peaked temperature dependence of the Gilbert damping coefficient which has been recently observed in such systems. For thicker normal layers the Gilbert damping monotonically increases down to the temperatures much smaller than the critical one. The suggested model paves the way to controlling the temperature dependence of the spin pumping by fabricating hybrid normal metal/superconductor spin sinks.

Influence of diets supplemented with Carica papaya and Chromolaena odorata leaf meals on performance, blood profile and gut integrity of broiler chickens

This study was carried out to investigate the effect of Carica papaya (CP) and Chromolaena odorata (CO) on growth performance, blood profile, gut integrity of broiler chicken. In a 42-day study, 200 one-day old Arbor Acre broilers were weighed and randomly allotted to 5 dietary treatments with 5 replicates having 8 birds in each group. The treatments were basal diet (negative control, NC), NC + 0.05% antibiotics (positive control, PC), NC + 3% CP, NC + 3% CO and NC + 1.5% CP + 1.5% CO in a completely randomised design. The growth performance indices were measured. On day 42, blood samples were collected, gut microbial population and histopathology were assayed following standard procedure. Results showed that average daily weight gain (g/bird/day) of birds on NC, PC and combination of 1.5% CP + 1.5% CO leaf meals were significantly similar at the finisher phase. The feed intake of birds on NC and PC was higher than those on 3% CO and combination of 1.5% CP + 1.5% CO leaf meals. The dietary treatment had effect on feed conversion ratio in the finisher phase. The highest total Lactobacillus count was observed in 3% CO leaf meal diet, while the antibiotics diet (PC) had the highest Escherichia coli count, and the lowest total Escherichia coli count (3.28 cfu x105) was recorded for birds on combination of 1.5% CP + 1.5% CO leaf meals. The histopathology of the gut shows that only those fed 3% CP had eroded villi of the mucosa layer, while all other treatments show normal mucosa layer, moderate inflammatory infiltration of the gland and lamina propia except those fed combinations of 1.5% CP + 1.5% CO. Conclusively, the combination of the leaf meals at 1.5% inclusion in broiler diet had positive effect on beneficial gut microbial population.

A retrospective clinicohistopathological study of psoriasis

Psoriasis is a common disease of unknown etiology, worldwide in distribution affecting men and women of all ages, races, and social strata. Psoriasis has diverse clinical variations, which mimic varied dermatological conditions and might need a histopathological confirmation of the diagnosis. Clinical and histopathological features have not been extensively studied in the Indian population. To study the clinical and histopathological features of psoriasis.This was a retrospective observational, single Centre study. 276 patients with psoriasis confirmed by biopsy were taken up for the study. Age, sex, duration, site of lesions, type of psoriasis, and individual histopathological parameters of psoriatic lesions were noted from the data and analyzed.The majority of patients belonged to the fourth decade with male preponderance. Chronic plaque psoriasis was the most common type, followed by palmoplantar psoriasis. Following histopathological features were seen, hyperkeratosis (85%), parakeratosis (72%), acanthosis (81%), hypogranulosis (53%), agranulosis (17%), hypergranulosis (12.7%), normal granular layer (10%), suprapapillary thinning (42%), elongation of rete ridges (73%), Munro micro abscess (34%), spongiform pustule of Kogoj (30%), capillary dilatation (90%) and lymphocytic dermal infiltration (97.8%).Diagnostic features of psoriasis in histopathology are not present in all the cases. Features of psoriasis are variable clinically and even in histopathology. Hence it is the combination of histopathological features of psoriasis with the clinical correlation that helps the physician to arrive at the diagnosis in doubtful cases.

Homonymous visual field defects in patients with multiple sclerosis: results of computerised perimetry and optical coherence tomography.

Visual dysfunction is frequent in multiple sclerosis, usually resulting from retrobulbar optic neuritis or papillitis. Less frequently, demyelinating lesions can affect the retrochiasmal pathways. There are few reports of homonymous visual field defects (HVFD) in multiple sclerosis and little is known about their evolution. The purpose of this study was to better define both the clinical profile and the evolution of HVFD in patients with multiple sclerosis. We performed a retrospective study of all multiple sclerosis patients who presented HVFD and were examined by automated static perimetry. A subset of patients benefited from macular assessment with optical coherence tomography (OCT). We also reviewed the worldwide literature on the subject. Twenty patients were retrieved from the neuro-ophthalmology database of the Hôpital Ophtalmique Jules-Gonin. There were 11 women and 9 men, and their average age was 35 ± 11 years. The relapsing-remitting form of multiple sclerosis was most common (18/20; 90%), the primary progressive form (1/20; 5%) and the secondary progressive form (1/20; 5%) were rare. HVFD were the presenting symptom of multiple sclerosis in seven patients (35%). The recovery was complete in 12/20 patients (60%), and the median time to recovery was 10 weeks (2-13 weeks). An incomplete recovery was found in 5/20 subjects (25%) and no recovery occurred in 3/20 subjects (15%). Magnetic resonance imaging disclosed a definite lesion explaining the HVFD in 7/11 patients: five within the optic radiations (71.4%), one within the optic tract (14.3%) and one within the lateral geniculate nucleus (14.3%). Our results were comparable to those compiled from our literature search (29 publications, totalling 70 cases). A recurrent episode of HVFD occurred in three patients (15%). OCT was performed in 10/20 patients. Retinal ganglion cell layer thickness was assessed and revealed a homonymous thinning in three patients, diffuse unilateral or bilateral thinning (resulting from previous episodes of optic neuritis) in six patients, and normal retinal ganglion cell layer thickness in one patient. HVFD in multiple sclerosis are found mostly in young patients with relapsing-remitting multiple sclerosis, which is consistent with the epidemiology of multiple sclerosis. HVFD can be the first manifestation of multiple sclerosis and have a relatively good prognosis. Like optic neuritis, HVFD can recur. The incidence of HVFD in multiple sclerosis is unknown, as it is probably underdiagnosed. Systematic automated static perimetry and OCT could help to determine the true incidence of HVFD in multiple sclerosis. &nbsp.

Macular hole closure patterns: an updated classification.

The classification of macular hole closure patterns (MHCPs) currently relies on time domain OCT allowing only "open" and "closed" statuses or is based on inner foveal contour shape. Both classification types give no information on retinal layer reconstitution. Novel sophisticated surgical techniques lead to previously unknown MHCPs, outdating existing classifications and urging new ones. The purpose of the present study is to introduce a new classification allowing proper description of all MHCPs resulting from newer surgeries and based on the restoration of retinal layers. Retrospective analysis of patients undergoing MH surgery with five different surgical techniques was performed. MHCPs were classified according to spectral domain optical coherence tomography (SD-OCT). Type 0: open MH (0A: flat margin, 0B: elevated, 0C: oedematous); type 1: closed MHs (1A: reconstitution all retinal layers; 1B interruption of the external layers; 1C interruption of internal layers); type 2: MH closed with autologous or heterologous filling tissue interrupting the normal foveal layered anatomy (2A: filling tissue through all layers; 2B reconstitution of normal inner retinal layers; 2C reconstitution of normal outer retinal layers; 2D H-shaped bridging of filling tissue). Closure rate was 95.2% (241/253). Surgical technique and vision correlated to closure pattern (p < 0.001). Type 1 MHCPs had the best post-operative visual acuity (VA) compared with type 2 and type 0 (p < 0.001). MHCPs 1A and 1C performed better than all others. MHCP at months 1 and 3 changed in 42/254 (16.5%) and remained stable in 212/254 (83.5%). Improvement in vision was higher in eyes with shifting closure pattern (0.57 ± 0.33 vs 0.51 ± 0.48 logMAR; p 0.021). MHCP classification based on retinal layer restoration properly comprises post-operative anatomic morphologies. MHCPs correlate the surgical technique and post-operative visual outcomes.

Graph-based Regularization on Embedding Layers for Recommendation

Neural networks have been extensively used in recommender systems. Embedding layers are not only necessary but also crucial for neural models in recommendation as a typical discrete task. In this article, we argue that the widely used l 2 regularization for normal neural layers (e.g., fully connected layers) is not ideal for embedding layers from the perspective of regularization theory in Reproducing Kernel Hilbert Space. More specifically, the l 2 regularization corresponds to the inner product and the distance in the Euclidean space where correlations between discrete objects (e.g., items) are not well captured. Inspired by this observation, we propose a graph-based regularization approach to serve as a counterpart of the l 2 regularization for embedding layers. The proposed regularization incurs almost no extra computational overhead especially when being trained with mini-batches. We also discuss its relationships to other approaches (namely, data augmentation, graph convolution, and joint learning) theoretically. We conducted extensive experiments on five publicly available datasets from various domains with two state-of-the-art recommendation models. Results show that given a kNN (k-nearest neighbor) graph constructed directly from training data without external information, the proposed approach significantly outperforms the l 2 regularization on all the datasets and achieves more notable improvements for long-tail users and items.

Concrete grade change in the layers of three-layer steel fibre reinforced concrete beams

Purpose: Determine the state of stress-strain, formation and development cracks, three-layer beam diagrams of load-compression stress, load-tension stress, load-vertical displacement relationships with a change in concrete grade. Design/methodology/approach: This paper presents the results of an ANSYS numerical simulation analysis involving stress-strain state and cracking of the steel fiber concrete layers of three-layer reinforced concrete beams with the upper and lower layers. With a cross-section of 150x300 mm, a total span of 2200 mm and an effective length of 2000 mm, the middle is a normal concrete layer. Under two-point loads, all the beam samples were tested. The research simulated three-layer concrete beams in different layers of beams with a change in concrete grade, and compared with and without the use of steel fibers in layers of concrete beams, including the nonlinearity of the material considered. Findings: A diagram of the formation and development of cracks in three-layer concrete beams has been constructed by the study results, determining the load at which the concrete beams begin to crack, the load at which the concrete beams are damaged. In the middle of three-layer steel fiber reinforced concrete beams, load-compression stress, loadtension stress, load-vertical displacement relationships are established. Study results show that these three-layer concrete beams appear to crack earlier than in other cases in cases 2 and 3, but the beam bearing capacity is damaged at 67 kN, the earliest in case 3. And case 6 at 116 kN is the latest. The effects of case 1 and case 3 are small compared with and without the use of steel fibers in cases, while the effects of case 5 and case 6 are very high. Research limitations/implications: The research focuses only on the change of concrete grade in the layers, but the input parameters affecting three-layer steel fiber concrete beams have not been researched, such as the number of tensile steel bars, tensile steel bar diameter, steel fiber content in concrete, thickness variation in three-layer concrete beam layers, etc. Practical implications: Provides a result of experimental study and ANSYS numerical simulation in multi-layer steel fiber concrete beams. Originality/value: The analysis of multi-layered steel fiber concrete beams using experimental and simulation methods shows that other parameters influencing the beams will continue to analysis the working stages of three-layer beams.

66‐3: The Way to Improve Black Circle Mura in Curved Display by Polyimide‐less Technology

In the fabrication of curved diplay, there always exist black circle mura, which is induced by the curvature. To improve this phenomenon, polyimide‐less technology was introduced. Polyimide‐less technology is a technology in which an additive can replace polyimide film to align LC molecules. In this technology, the additive added in liquid crystal (LC) host can not only align the LC molecules, but also have different pretilt angle generation ratio compared with PI film. In this paper, we fabricated curved panels using CF substrate with PI and TFT substrate without PI.The additive in PI‐less liquid crystals could anchor the TFT substrate and align the LC molecules on the TFT side. After UV process, the CF substrate had smaller pretilt angle. And the black circle mura appeared in the curved panel could be solved completely. Then we also studied the alignment, optical and image sticking performance, there existed no difference between the curved panels using PI‐less technology and the curved ones with normal PI layers.

Strain-Controlled Superconductivity in Few-Layer NbSe2.

The controlled tunability of superconductivity in low-dimensional materials may enable new quantum devices. Particularly in triplet or topological superconductors, tunneling devices such as Josephson junctions, etc., can demonstrate exotic functionalities. The tunnel barrier, an insulating or normal material layer separating two superconductors, is a key component for the junctions. Thin layers of NbSe2 have been shown as a superconductor with strong spin orbit coupling, which can give rise to topological superconductivity if driven by a large magnetic exchange field. Here we demonstrate the superconductor-insulator transitions in epitaxially grown few-layer NbSe2 with wafer-scale uniformity on insulating substrates. We provide the electrical transport, Raman spectroscopy, cross-sectional transmission electron microscopy, and X-ray diffraction characterizations of the insulating phase. We show that the superconductor-insulator transition is driven by strain, which also causes characteristic energy shifts of the Raman modes. Our observation paves the way for high-quality heterojunction tunnel barriers to be seamlessly built into epitaxial NbSe2 itself, thereby enabling highly scalable tunneling devices for superconductor-based quantum electronics.

Distortions to the penetration depth and coherence length of superconductor/normal-metal superlattices

Superconducting ($S$) thin film superlattices composed of Nb and a normal metal spacer ($N$) have been extensively utilized in Josephson junctions given their favorable surface roughness compared to Nb films of comparable thickness. In this work, we characterize the London penetration depth and Ginzburg-Landau coherence lengths of $S/N$ superlattices using polarized neutron reflectometry and electrical transport. Despite the normal metal spacer layers being only approximately 8% of the total superlattice thickness, we surprisingly find that the introduction of these thin $N$ spacers between $S$ layers leads to a dramatic increase in the measured London penetration depth compared to that of a single Nb film of comparable thickness. Using the measured values for the effective in- and out-of-plane coherence lengths, we quantify the induced anisotropy of the superlattice samples and compare to a single Nb film sample. From these results, we find that that the superlattices behave similarly to layered 2D superconductors.