Graphene-Based Tunable Dual-Frequency Terahertz Sensor.

A tunable dual-band terahertz sensor based on graphene is proposed. The sensor consists of a metal bottom layer, a middle dielectric layer, and single-layer graphene patterned with four strips on the top. The numerical simulations results show that the proposed sensor exhibits two significant absorption peaks at 2.58 THz and 6.07 THz. The corresponding absorption rates are as high as nearly 100% and 98%, respectively. The corresponding quality factor (Q) value is 11.8 at 2.58 THz and 29.6 at 6.07 THz. By adjusting the external electric field or chemical doping of graphene, the positions of the dual-frequency resonance peak can be dynamically tuned. The excitation of plasma resonance in graphene can illustrate the mechanism of the sensor. To verify the practical application of the device, the terahertz response of different kinds and different thicknesses of the analyte is investigated and analyzed. A phenomenon of obvious frequency shifts of the two resonance peaks can be observed. Therefore, the proposed sensor has great potential applications in terahertz fields, such as material characterization, medical diagnosis, and environmental monitoring.

Analysis of factors influencing the intravertebral shell phenomenon after posterior reduction internal fixation of thoracolumbar fracture: a retrospective study.

STUDY DESIGN: A retrospective study. PURPOSE: The study objectives were as follows: 1) to analyze the factors influencing the occurrence of the intravertebral shell phenomenon (ISP) after thoracolumbar spinal fracture surgery and the evolutionary outcome of this phenomenon; and 2) to make recommendations for the clinical prevention and treatment of ISP. METHODS: We retrospectively analyzed 331 patients with single-segment fractures of the thoracolumbar spine treated with internal fixation via a pedicle screw-rod system. Univariate and multivariate logistic regression were used to analyze factors influencing ISP. RESULTS: A total of 260 patients (78.5%) developed ISP after surgery. Reduced bone mineral density, screw insertion depth, degree of vertebral body injury, and excessive vertebral body spreading were significantly associated with the occurrence of ISP (P < 0.05). A total of 166 of the 260 patients were reviewed via CT at 1 year postoperatively. Among them, 104 patients (62.6%) showed shrinkage or healed vertebral cavities, and 62 patients (37.4%) showed enlarged vertebral cavities or collapsed endplates. CONCLUSION: In clinical management, surgeons need to focus on risk factors for ISP, which include decreased bone density, preoperative vertebral overcompression, intraoperative vertebral overextension, screw insertion depth, and the degree of vertebral repositioning. At the 1-year postoperative follow-up, some of the vertebrae with ISP failed to heal or even showed vertebral cleft enlargement, which would affect the stability of the internal fracture fixation device and the quality of the patient's daily life.

Co-Production of Nattokinase and Poly (γ-Glutamic Acid) Under Solid-State Fermentation Using Soybean and Rice Husk

ABSTRACTThe aim of this work was to study the co-production of nattokinase and poly (γ-glutamic acid) by Bacillus subtilis natto with soybean and rice husk under solid-state fermentation (SSF). The results showed that the size of soybean particle and rice husk significantly improved the co-production of nattokinase and poly (γ-glutamic acid), yielding 2503.4 IU/gs and 320 mg/gs, respectively in the improved culture medium composed of 16.7% soybean flour and 13.3% rice husk with 70% water content. The yields increased by approximate 7- and 2-fold factor relative to their original ones. Thus, the co-production of nattokinase and poly (γ-glutamic acid) under SSF could be considered as an efficient method to exploit agro-residues for economical production of some higher-value products.