Crossed Andreev Reflection and Elastic Cotunneling in Three Quantum Dots Coupled by Superconductors.

The formation of a topological superconducting phase in a quantum-dot-based Kitaev chain requires nearest neighbor crossed Andreev reflection and elastic cotunneling. Here, we report on a hybrid InSb nanowire in a three-site Kitaev chain geometry-the smallest system with well-defined bulk and edge-where two superconductor-semiconductor hybrids separate three quantum dots. We demonstrate pairwise crossed Andreev reflection and elastic cotunneling between both pairs of neighboring dots and show sequential tunneling processes involving all three quantum dots. These results are the next step toward the realization of topological superconductivity in long Kitaev chain devices with many coupled quantum dots.

Spin-filtered measurements of Andreev bound states in semiconductor-superconductor nanowire devices.

Semiconductor nanowires coupled to superconductors can host Andreev bound states with distinct spin and parity, including a spin-zero state with an even number of electrons and a spin-1/2 state with odd-parity. Considering the difference in spin of the even and odd states, spin-filtered measurements can reveal the underlying ground state. To directly measure the spin of single-electron excitations, we probe an Andreev bound state using a spin-polarized quantum dot that acts as a bipolar spin filter, in combination with a non-polarized tunnel junction in a three-terminal circuit. We observe a spin-polarized excitation spectrum of the Andreev bound state, which can be fully spin-polarized, despite strong spin-orbit interaction in the InSb nanowires. Decoupling the hybrid from the normal lead causes a current blockade, by trapping the Andreev bound state in an excited state. Spin-polarized spectroscopy of hybrid nanowire devices, as demonstrated here, is proposed as an experimental tool to support the observation of topological superconductivity.

Imaging characterization of myocardial function, fibrosis, and perfusion in a nonhuman primate model with heart failure-like features.

Introduction: The availability of a human-like chronic heart failure (HF) animal model was critical for affiliating development of novel therapeutic drug treatments. With the close physiology relatedness to humans, the non-human primate (NHP) HF model would be valuable to better understand the pathophysiology and pharmacology of HF. The purpose of this work was to present preliminary cardiac image findings using echocardiography and cardiovascular magnetic resonance (CMR) in a HF-like cynomolgus macaque model. Methods: The NHP diet-induced model developed cardiac phenotypes that exhibited diastolic dysfunction with reduced left ventricular ejection fraction (LVEF) or preserved LVEF. Twenty cynomolgus monkeys with cardiac dysfunction were selected by echocardiography and subsequently separated into two groups, LVEF < 65% (termed as HFrEF, n = 10) and LVEF ≥ 65% with diastolic dysfunction (termed as HFpEF, n = 10). Another group of ten healthy monkeys was used as the healthy control. All monkeys underwent a CMR study to measure global longitudinal strain (GLS), myocardial extracellular volume (ECV), and late gadolinium enhancement (LGE). In healthy controls and HFpEF group, quantitative perfusion imaging scans at rest and under dobutamine stress were performed and myocardial perfusion reserve (MPR) was subsequently obtained. Results: No LGE was observed in any monkey. Monkeys with HF-like features were significantly older, compared to the healthy control group. There were significant differences among the three groups in ECV (20.79 ± 3.65% in healthy controls; 27.06 ± 3.37% in HFpEF group, and 31.11 ± 4.50% in HFrEFgroup, p < 0.001), as well as for stress perfusion (2.40 ± 0.34 ml/min/g in healthy controls vs. 1.28 ± 0.24 ml/min/g in HFpEF group, p < 0.01) and corresponding MPR (1.83 ± 0.3 vs. 1.35 ± 0.29, p < 0.01). After adjusting for age, ECV (p = 0.01) and MPR (p = 0.048) still showed significant differences among the three groups. Conclusion: Our preliminary imaging findings demonstrated cardiac dysfunction, elevated ECV, and/or reduced MPR in this HF-like NHP model. This pilot study laid the foundation for further mechanistic research and the development of a drug testing platform for distinct HF pathophysiology.

Enhanced recovery after microdiscectomy: reductions in opioid use, length of stay and cost.

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols are widely used worldwide. Recently, studies of the ERAS program in spinal surgery subspecialties have been reported. The aim of this study was to evaluate the impacts of ERAS in minimally invasive microdiscectomy (MD) surgery. METHODS: This was a retrospective cohort study of patients undergoing MD at a single center. From March 2018 to March 2021, 286 patients were in the ERAS group. A total of 140 patients from March 2017 to February 2018 were in the conventional group. The outcomes included length of stay (LOS), the postoperative numeric rating scale (NRS), complications, 30-day readmission rate, 30-day reoperation rate and cost. Moreover, perioperative factors were also evaluated. RESULTS: Compared with the conventional group, the LOS and cost were reduced in the ERAS group. There were no significant differences in the NRS, complication rate, 30-day readmission or reoperation rates between the groups. Furthermore, postoperative drainage volume, and postoperative opioid use were lower in the ERAS group. CONCLUSIONS: The ERAS protocol for MD surgery reduces LOS, cost and opioid use and accelerates patient recovery.

Electrostatic control of the proximity effect in the bulk of semiconductor-superconductor hybrids.

The proximity effect in semiconductor-superconductor nanowires is expected to generate an induced gap in the semiconductor. The magnitude of this induced gap, together with the semiconductor properties like spin-orbit coupling and g-factor, depends on the coupling between the materials. It is predicted that this coupling can be adjusted through the use of electric fields. We study this phenomenon in InSb/Al/Pt hybrids using nonlocal spectroscopy. We show that these hybrids can be tuned such that the semiconductor and superconductor are strongly coupled. In this case, the induced gap is similar to the superconducting gap in the Al/Pt shell and closes only at high magnetic fields. In contrast, the coupling can be suppressed which leads to a strong reduction of the induced gap and critical magnetic field. At the crossover between the strong-coupling and weak-coupling regimes, we observe the closing and reopening of the induced gap in the bulk of a nanowire. Contrary to expectations, it is not accompanied by the formation of zero-bias peaks in the local conductance spectra. As a result, this cannot be attributed conclusively to the anticipated topological phase transition and we discuss possible alternative explanations.

Application of metagenomic next-generation sequencing in the detection of pathogens in spinal infections.

BACKGROUND CONTEXT: The precise diagnosis and treatment of spinal infections (SI) remains challenging for spine surgeons. Identifying the pathogens of SI through metagenomic next-generation sequencing (mNGS) may be a key approach to addressing this challenge. PURPOSE: To evaluate the accuracy and applicability of mNGS in determining the etiology of SI. STUDY DESIGN: Diagnostic test study. PATIENT SAMPLE: Twenty-five patients who had a clinical suspicion of SI and underwent mNGS testing. OUTCOME MEASURES: The specificity, sensitivity, and time cost of mNGS and bacterial culture were compared. Clinical outcomes were assessed using the numeric rating scale (NRS) score, Oswestry Disability Index (ODI), and the Japanese Orthopedic Association (JOA) score. Demographic data and laboratory results (blood cell count (WBC), erythrocyte sedimentation rate (ESR), neutrophil percentage (NEUT%), and C-reactive protein level (CRP) were also evaluated. METHODS: In this retrospective study, samples were obtained from 25 eligible patients via surgery or CT-guided puncture and subjected to histopathological examination, bacterial culture, and mNGS. The sensitivity and specificity of the bacterial cultures and mNGS were calculated with respect to the histopathological results as a reference. Postoperative antibiotics or antituberculosis drugs were administered on the basis of mNGS results, combined with clinical manifestations, imaging examination, and histopathology. The changes of clinical outcomes and laboratory results after treatment were observed. RESULTS: Of the 25 patients, 21 had a positive pathology, of which 10 showed a tuberculous pathology, and the remaining 11 showed a nontuberculous inflammatory pathology. The sensitivity of mNGS was higher than that of the bacterial culture. However, the difference in specificity between bacterial culture and mNGS was not significant. Moreover, the time needed to perform mNGS was significantly lower than that of bacterial culture and pathology. All patients were followed up for more than three months, and CRP and NEUT% significantly decreased by three months after treatment. There was no significant difference in WBC and ESR. The ODI, NRS and JOA scores were significantly improved after treatment. CONCLUSION: Metagenomic next-generation sequencing technology can play an important role in the detection of pathogens in SI and should be further investigated and applied in future studies.

Realization of a minimal Kitaev chain in coupled quantum dots.

Majorana bound states constitute one of the simplest examples of emergent non-Abelian excitations in condensed matter physics. A toy model proposed by Kitaev shows that such states can arise at the ends of a spinless p-wave superconducting chain1. Practical proposals for its realization2,3 require coupling neighbouring quantum dots (QDs) in a chain through both electron tunnelling and crossed Andreev reflection4. Although both processes have been observed in semiconducting nanowires and carbon nanotubes5-8, crossed-Andreev interaction was neither easily tunable nor strong enough to induce coherent hybridization of dot states. Here we demonstrate the simultaneous presence of all necessary ingredients for an artificial Kitaev chain: two spin-polarized QDs in an InSb nanowire strongly coupled by both elastic co-tunnelling (ECT) and crossed Andreev reflection (CAR). We fine-tune this system to a sweet spot where a pair of poor man's Majorana states is predicted to appear. At this sweet spot, the transport characteristics satisfy the theoretical predictions for such a system, including pairwise correlation, zero charge and stability against local perturbations. Although the simple system presented here can be scaled to simulate a full Kitaev chain with an emergent topological order, it can also be used imminently to explore relevant physics related to non-Abelian anyons.

A novel classification based on magnetic resonance imaging for individualized surgical strategies of lumbar disc herniation.

INTRODUCTION: Although the anatomy and pathology of lumbar disc herniation (LDH) have been clearly defined and classified in many studies, its imaging definition and classification still needs further clarification. This study intends to propose a novel classification and individualized surgical strategy for LDH based on preoperative magnetic resonance imaging (MRI). MATERIALS AND METHODS: According to MRI features, LDH types were identified, and the corresponding surgical strategies were formulated to accurately remove the herniated discs while minimizing the disturbance to the normal disc. We retrospectively analyzed prospectively collected data of LDH patients who underwent surgery guided by this classification system. RESULTS: This study included 357 patients with LDH who underwent tubular microdiscectomy. LDH was classified into four types based on MRI features. The inter- and intra-observer agreement using this classification was good. The follow-up results showed that surgery improved visual analog scale scores for low-back and leg pain and the Oswestry disability index in patients with different LDH types. The average recurrence rate at 1-5 years postoperatively was 5.62%. There was no significant difference in recurrence rates among the four LDH types (3.7-6.2%). MRI showed no significant differences in the Pfirrmann grade and disc height index of the operated segment between before surgery and 1-3 years after surgery. The operated segments did not show faster disc degeneration rates compared to adjacent proximal segments. CONCLUSIONS: We proposed a novel classification system and an individualized surgical strategy for LDH based on preoperative MRI. Further, the surgical suitable interventions guided by this system achieved good clinical outcomes and mild recurrence rates.

Posterior Multisegment Apical Convex plus Concave Intervertebral Release Combined with Posterior Column Osteotomy for the Treatment of Rigid Thoracic/Thoracolumbar Scoliosis.

BACKGROUND: Intervertebral release (IVR) in the apical region is critical for full release of a rigid spine. Previous studies have mainly reported IVR techniques using an anterior approach or posterior apical convex IVR. We first report the surgical procedure of posterior multisegment apical convex plus concave IVR combined with posterior column osteotomy (PCO) for treating rigid thoracic/thoracolumbar scoliosis. METHODS: This study retrospectively analyzed clinical, radiologic outcomes and technique notes of 18 patients with rigid scoliosis treated with posterior multisegment convex plus concave IVR combined with PCO. RESULTS: The preoperative, postoperative, and final follow-up mean sagittal Cobb angles of the main curve were 75.2° (58.7°-110.2°), 18.4° (9°-35.1°), and 19.0° (8.2°-36.3°), respectively. The mean correction rate was 75.3% (66.7%-86.7%). In cases of thoracolumbar kyphosis, the preoperative, postoperative, and final follow-up mean sagittal Cobb angles were 45.7° (40.5°-52.6°), 18.8° (10.2°-27.5°), and 19.8° (11.1°-29°), respectively. The mean correction rate was 57% (42.1%-72.6%). The mean axial vertebral rotation (AVR) in the IVR region was 24.4° (14.3°-46.3°) preoperatively and was corrected to 10.9° (10.9°-26.6°) postoperatively. The mean correction rate for AVR was 55.9% (41.1%-78.6%). The coronal and sagittal Cobb angles and AVR postoperatively were significantly lower than those preoperatively (P < 0.001). This case series reported 2 cases of pleural effusion and 1 case of wound infection. CONCLUSIONS: Single posterior multilevel apical convex plus concave IVR combined with PCO is a safe and effective surgical method for treating rigid thoracic/thoracolumbar scoliosis that does not need 3-column osteotomy.

Singlet and triplet Cooper pair splitting in hybrid superconducting nanowires.

In most naturally occurring superconductors, electrons with opposite spins form Cooper pairs. This includes both conventional s-wave superconductors such as aluminium, as well as high-transition-temperature, d-wave superconductors. Materials with intrinsic p-wave superconductivity, hosting Cooper pairs made of equal-spin electrons, have not been conclusively identified, nor synthesized, despite promising progress1-3. Instead, engineered platforms where s-wave superconductors are brought into contact with magnetic materials have shown convincing signatures of equal-spin pairing4-6. Here we directly measure equal-spin pairing between spin-polarized quantum dots. This pairing is proximity-induced from an s-wave superconductor into a semiconducting nanowire with strong spin-orbit interaction. We demonstrate such pairing by showing that breaking a Cooper pair can result in two electrons with equal spin polarization. Our results demonstrate controllable detection of singlet and triplet pairing between the quantum dots. Achieving such triplet pairing in a sequence of quantum dots will be required for realizing an artificial Kitaev chain7-9.

Spin-Mixing Enhanced Proximity Effect in Aluminum-Based Superconductor-Semiconductor Hybrids.

In superconducting quantum circuits, aluminum is one of the most widely used materials. It is currently also the superconductor of choice for the development of topological qubits. However, aluminum-based devices suffer from poor magnetic field compatibility. Herein, this limitation is resolved by showing that adatoms of heavy elements (e.g., platinum) increase the critical field of thin aluminum films by more than a factor of two. Using tunnel junctions, it is shown that the increased field resilience originates from spin-orbit scattering introduced by Pt. This property is exploited in the context of the superconducting proximity effect in semiconductor-superconductor hybrids, where it is shown that InSb nanowires strongly coupled to Al/Pt films can maintain superconductivity up to 7 T. The two-electron charging effect is shown to be robust against the presence of heavy adatoms. Additionally, non-local spectroscopy is used in a three-terminal geometry to probe the bulk of hybrid devices, showing that it remains free of sub-gap states. Finally, it is demonstrated that proximitized semiconductor states maintain their ability to Zeeman-split in an applied magnetic field. Combined with the chemical stability and well-known fabrication routes of aluminum, Al/Pt emerges as the natural successor to Al-based systems and is a compelling alternative to other superconductors, whenever high-field resilience is required.

An enhanced recovery after surgery pathway: LOS reduction, rapid discharge and minimal complications after anterior cervical spine surgery.

BACKGROUND: Enhance recovery after surgery (ERAS) is a new and promising paradigm for spine surgery. The purpose of this study is to investigate the effectiveness and safety of a multimodal and evidence-based ERAS pathway to the patients undergoing anterior cervical discectomy and fusion (ACDF). METHODS: The patients treated with the ACDF-ERAS pathway were compared with a historical cohort of patients who underwent ACDF before ERAS pathway implementation. Primary outcome was length of stay (LOS). Secondary outcomes included cost, MacNab grading, complication rates and 90-day readmission and reoperation. And perioperative factors and postoperative complications were reviewed. RESULTS: The ERAS protocol was composed of 21 components. More patients undergoing multi-level surgery (n ≥ 3) were included in the ERAS group. The ERAS group showed a shorter LOS and a lower cost than the conventional group. The postoperative satisfaction of patients in ERAS group was better than that in conventional group. In addition, the rate of overall complications was significantly higher in the conventional group than that in the ERAS group. There were no significant differences in operative time, postoperative drainage, or 90-day readmission and reoperation. CONCLUSIONS: The ACDF-tailored ERAS pathway can reduce LOS, cost and postoperative complications, and improve patient satisfaction without increasing 90-day readmission and reoperation.

Tunable Superconducting Coupling of Quantum Dots via Andreev Bound States in Semiconductor-Superconductor Nanowires.

Semiconductor quantum dots have proven to be a useful platform for quantum simulation in the solid state. However, implementing a superconducting coupling between quantum dots mediated by a Cooper pair has so far suffered from limited tunability and strong suppression. This has limited applications such as Cooper pair splitting and quantum dot simulation of topological Kitaev chains. In this Letter, we propose how to mediate tunable effective couplings via Andreev bound states in a semiconductor-superconductor nanowire connecting two quantum dots. We show that in this way it is possible to individually control both the coupling mediated by Cooper pairs and by single electrons by changing the properties of the Andreev bound states with easily accessible experimental parameters. In addition, the problem of coupling suppression is greatly mitigated. We also propose how to experimentally extract the coupling strengths from resonant current in a three-terminal junction. Our proposal will enable future experiments that have not been possible so far.

A robust fiber-based quantum thermometer coupled with nitrogen-vacancy centers.

The nitrogen-vacancy center in diamond has been broadly applied in quantum sensing since it is sensitive to different physical quantities. Meanwhile, it is difficult to isolate disturbances from unwanted physical quantities in practical applications. Here, we present a fiber-based quantum thermometer by tracking the sharp-dip in the zero-field optically detected magnetic resonance spectrum in a high-density nitrogen-vacancy ensemble. Such a scheme can not only significantly isolate the magnetic field and microwave power drift but also improve the temperature sensitivity. Thanks to its simplicity and compatibility in implementation and robustness, this quantum thermometer is then applied to the surface temperature imaging of an electronic chip with a sensitivity of 18mK/Hz. It thus paves the way to high sensitive temperature measurements in ambiguous environments.

Amorphization-induced surface electronic states modulation of cobaltous oxide nanosheets for lithium-sulfur batteries.

Lithium-sulfur batteries show great potential to achieve high-energy-density storage, but their long-term stability is still limited due to the shuttle effect caused by the dissolution of polysulfides into electrolyte. Herein, we report a strategy of significantly improving the polysulfides adsorption capability of cobaltous oxide by amorphization-induced surface electronic states modulation. The amorphous cobaltous oxide nanosheets as the cathode additives for lithium-sulfur batteries demonstrates the rate capability and cycling stability with an initial capacity of 1248.2 mAh g-1 at 1 C and a substantial capacity retention of 1037.3 mAh g-1 after 500 cycles. X-ray absorption spectroscopy analysis reveal that the coordination structures and symmetry of ligand field around Co atoms of cobaltous oxide nanosheets are notably changed after amorphization. Moreover, DFT studies further indicate that amorphization-induced re-distribution of d orbital makes more electrons occupy high energy level, thereby resulting in a high binding energy with polysulfides for favorable adsorption.

Efficient photocatalytic degradation of volatile organic compounds over carbon quantum dots decorated Bi2WO6 under visible light.

A series of CQDs/Bi2WO6 (CBW) hybrid materials with different loading amounts of carbon quantum dots (CQDs) were prepared via a facile in situ hydrothermal method. As determined by multiple techniques including XRD, TEM, UV-vis, PL, TPR, and XPS, the CBW possessed expanded visible light response interval, decreased recombination rate of the photogenerated electron hole, and enhanced oxidation ability as compared with the pristine Bi2WO6. In addition, with different loading amounts of CQDs, the optical and electronic properties of the corresponding CBW were different. These CBW materials performed superior activities to the pristine Bi2WO6 in the photodegradation of VOCs under visible light, among which the CBW-2 demonstrated the best activity of almost complete degradation within only 120 min. Moreover, the CBW-2 exhibited high stability and reusability after five cycles.

Electrochemical preparation and properties of a Mg-Li-Y alloy via co-reduction of Mg(ii) and Y(iii) in chloride melts.

Mg-Li based alloys have been widely used in various fields. However, the widespread use of Mg-Li based alloys were restricted by their poor properties. The addition of rare earth element in Mg-Li can significantly improve the properties of alloys. In the present work, different electrochemical methods were used to investigate the electrochemical behavior of Y(iii) on the W electrode in LiCl-KCl melts and LiCl-KCl-MgCl2 melts. In LiCl-KCl melts, typical cyclic voltammetry was used to study the electrochemical mechanism and thermodynamic parameters for the reduction of Y(iii) to metallic Y. In LiCl-KCl-MgCl2 melts, the formation mechanism of Mg-Y intermetallic compounds was investigated, and the results showed that only one kind of Mg-Y intermetallic compound was formed under our experimental conditions. Mg-Li-Y alloys were prepared via galvanostatic electrolysis, and XRD and SEM equipped with EDS analysis were used to analyze the samples. Because of the restrictions of EDS analysis, ICP-AES was used to analyze the Li content in Mg-Li-Y alloys. The microhardness and Young's modulus of the Mg-Li-Y alloys were then evaluated.

Publisher Correction: Orexin signaling modulates synchronized excitation in the sublaterodorsal tegmental nucleus to stabilize REM sleep.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.