All-fiber laser system for all-optical 87Rb Bose Einstein condensate to space application.

In the development of the Cold Atom Physics Research Rack (CAPR) on board the Chinese Space Station, the laser system plays a critical role in preparing the all-optical 87 R b Bose-Einstein condensates (BECs). An all-fiber laser system has been developed for CAPR to provide the required optical fields for atom interaction and to maintain the beam pointing in long-term operation. The laser system integrates a 780 nm fiber laser system and an all-fiber optical control module for sub-Doppler cooling, as well as an all-fiber 1064 nm laser system for evaporative cooling. The high-power, single-frequency 780 nm lasers are achieved through rare-Earth doped fiber amplification, fiber frequency-doubling, and frequency stabilization technology. The all-fiber optical control module divides the output of the 780 nm laser system into 15 channels and regulates them for cooling, trapping, and probing atoms. Moreover, the power consistency of each pair of cooling beams is ensured by three power tracking modules, which is a prerequisite for maintaining stable MOT and molasses. A high-power, compact, controlled-flexible, and highly stable l064 nm all-fiber laser system employing two-stage ytterbium-doped fiber amplifier (YDFA) technology has been designed for evaporative cooling in the optical dipole trap (ODT). Finally, an all-optical 87 R b BEC is realized with this all-fiber laser system, which provides an alternative solution for trapping and manipulating ultra-cold atoms in challenging environmental conditions.

Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface.

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

Clinical Efficacy and Safety of Percutaneous Spinal Endoscopy versus Traditional Open Surgery for Lumbar Disc Herniation: Systematic Review and Meta-Analysis.

Objective: Systematic analysis of the incidence of percutaneous spinal endoscopic technique and traditional open surgery for lumbar disc herniation. Methods: A randomized controlled trial (RCT) and cohort study on complications related to traditional open surgery was searched on the MEDLINE, Cochrane Library, PubMed, Web of Science, Chinese journal full-text database (CNKI), Wanfang, and Embase database. Language is not limited. The quality of each study was evaluated, various complications were compiled into electronic baseline tables, and the data from these studies were available. Meta-analysis and synthesis were performed with the RevMan 5.3 software to evaluate the statistical significance of both surgical techniques in terms of various complications. Results: 12 studies were eventually included, and a total of 2,797 patients were included in the analysis. Meta-analysis results showed that there was no statistical difference in postoperative paresthesia between percutaneous spinal endoscopy and traditional open surgery (OR = 1.17, 95% CI (0.82, 1.66), P = 0.38, I 2 = 0%, Z = 0.88), direct nerve root damage (OR = 0.79, 95% CI (0.58, 1.07), P = 0.13, I 2 = 73%, Z = 1.52), and intraoperative hemorrhage and hematoma formation (OR = 1.00, 95% CI (0.67, 1.48), P = 0.99, I 2 = 0%, Z = 0.02), but there was a statistical difference in disc recurrence (OR = 2.24, 95% CI (1.56, 3.21), P < 0.0001, I 2 = 81%, Z = 4.39). Conclusion: Compared with the traditional open surgical treatment of lumbar disc herniation, percutaneous spinal endoscopic technology has obvious advantages in reducing nerve root injury, dural injury, and surgical area wound complications, but it is limited to preventing the technical characteristics of the surgical site, which is worse than that of open surgery.

Facile synthesis of vacancy-induced 2H-MoS2 nanosheets and defect investigation for supercapacitor application.

In this paper, a 2D molybdenum disulfide (MoS2) nanosheet is prepared via a one-step hydrothermal method as electrode material for supercapacitors. Meanwhile, a series of MoS2-x nanostructures with sulfur vacancies have been successfully obtained in an Ar/H2 mixed atmosphere at different annealing temperatures. The prepared materials were characterized by XRD, HR-TEM, Raman and XPS to identify their morphology and crystal properties. MoS2-x assembled by interconnected nanosheets (MoS2-x -700) provides a maximum specific capacitance of 143.12 F g-1 at a current density of 1.0 A g-1 with 87.1% of initial capacitance reserved after 5000 cycles. The outstanding performance of the annealed MoS2-x nanosheets in sodium storage is mainly attributed to the synergistic effect of the unique interconnected structure and the abundant active vacancy generated by the sulfur vacancies. Atomic models of sulfur vacancy defects on the basal plane, Mo-edge and S-edge were established and the electronic properties of MoS2-x were further evaluated assisted by first principles theory. DFT calculation results show that sulfur vacancy defects can provide additional empty states near the Fermi level and induce unpaired electrons, thus increasing the carrier density and improving electrical conductivity. Our findings in this work provide experimental and theoretical evidence of improving the electrochemical performance of 2H-MoS2 nanosheets by annealing treatment.

In situ synthesis of nanostructured Fe3O4@TiO2 composite grown on activated carbon cloth as a binder-free electrode for high performance supercapacitors.

Transition metal oxide (TMO) nanomaterials with regular morphology have received widening research attention as electrode materials due to their improved electrochemical characteristics. In this study we present the successful fabrication of an Fe3O4/TiO2 nanocomposite grown on a carbon cloth (Fe3O4/TiO2@C) used as a high-efficiency electrochemical supercapacitor electrode. Flexible electrodes are directly used for asymmetric supercapacitors without any binder. The increased specific surface area of the TiO2 nanorod arrays provides sufficient adsorption sites for Fe3O4 nanoparticles. An asymmetric supercapacitor composed of Fe3O4/TiO2@C is tested in 1 M Na2SO3 electrolyte, and the synergistic effects of fast reversible Faraday reaction on the Fe3O4/TiO2 surface and the highly conductive network formed by TiO2@C help the electrode to achieve a high areal capacitance of 304.1 mF cm-2 at a current density of 1 mA cm-2 and excellent cycling stability with 90.7% capacitance retention at 5 mA cm-2 after 10 000 cycles. As a result, novel synthesis of a binder-free Fe3O4/TiO2@C electrode provides a feasible approach for developing competitive candidates in supercapacitor applications.

Incidence and Risk Factors of Cervical Kyphosis in Patients with Adolescent Idiopathic Scoliosis.

BACKGROUND: Cervical kyphosis (CK) has been reported in patients with adolescent idiopathic scoliosis (AIS). The report about the incidence of CK between patients with AIS and normal populations was little. Patients included in previous studies often required scoliosis surgery (Cobb angle ≥40°), which does not represent all patients with AIS. The aims of this study were to compare incidence of CK between patients with AIS (Cobb angle >10°) and an age-matched normal population and to identify risk factors related to CK, especially coronal parameters that have rarely been studied in current literature. METHODS: Patients with AIS (n = 112) and asymptomatic subjects from the general population (control group; n = 40) were retrospectively analyzed. Radiographic parameters of coronal and sagittal plane were measured on full-length spine x-rays. Patients with AIS were divided into 2 groups based on cervical lordosis angle: cervical lordosis and CK. RESULTS: CK was observed in 14 of 40 (35%) subjects in the control group and 68 of 112 (60.7%) patients with AIS. Several parameters were related to CK, including major curve, proximal thoracic, and main thoracic Cobb angle; proximal thoracic kyphosis angle; main thoracic kyphosis angle; T1 slope; sagittal vertical axis; vertical distance between C7 plumb line and center sacral vertical line; apical vertebral translation; T1 coronal tilt; and lumbar pelvic relationship. Logistic regression identified main thoracic Cobb angle, main thoracic kyphosis angle, sagittal vertical axis, lumbar pelvic relationship, and apical vertebral translation as independent risk factors of CK. CONCLUSIONS: Incidence of CK increases in patients with AIS relative to normal subjects. Coronal parameters of the spine could influence cervical sagittal alignment.

Silencing tumor necrosis factor-alpha in vitro from small interfering RNA-decorated titanium nanotube array can facilitate osteogenic differentiation of mesenchymal stem cells.

Titanium implants are known for their bone bonding ability. However, the osseointegration may be severely disturbed in the inflammation environment. In order to enhance osseointegration of the implant in an inflamed environment, the small interfering RNA (siRNA) targeting tumor necrosis factor alpha (TNF-α) was used to functionalize titanium surface for gene silencing. The chitosan-tripolyphosphate-hyaluronate complexes were used to formulate nanoparticles (NPs) with siRNA, which were adsorbed directly by the anodized titanium surface. The surface characterization was analyzed by scanning electron microscope, atomic force microscopy, as well as contact angle measurement. The fluorescence microscope was used to monitor the degradation of the layer. The coculture system was established with mesenchymal stem cells (MSCs) grown directly on functionalized titanium surface and RAW264.7 cells (preactivated by lipopolysaccharide) grown upside in a transwell chamber. The transfection and knockdown efficiency of TNF-α in RAW264.7 cells were determined by fluorescence microscope, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay. The cytoskeleton and osteogenic differentiation of MSCs were also analyzed. Regular vertical aligned nanotubes (~100 nm diameter and ~300 nm length) were generated after anodization of polished titanium. After loading with NPs, the nanotubes were filled and covered by a layer of amorphous particles. The surface topography changed and wettability decreased after covering with NPs. As expected, a burst degradation of the film was observed, which could provide sufficient NPs in the released supernatant and result in transfection and knockdown effects in RAW264.7 cells. The cytoskeleton arrangement of MSCs was elongated and the osteogenic differentiation was also significantly improved on NPs loading surface. In conclusion, the siRNA decorated titanium implant could simultaneously suppress inflammation and improve osteogenesis, which may be suitable for peri-implant bone formation under inflammatory conditions.