Broad/narrowband switchable terahertz absorber based on Dirac semimetal and strontium titanate for temperature sensing.

A broadband and narrowband switchable terahertz (THz) absorber based on a bulk Dirac semimetal (BDS) and strontium titanate (STO) is proposed. Narrowband and broadband absorption can be switched by adjusting the Fermi level of the BDS. When the Fermi level of the BDS is 100 meV, the device is an absorber with three narrowband absorption peaks. The frequencies are 0.44, 0.86, and 1.96 THz, respectively, when the temperature of STO is 250 K. By adjusting the temperature of STO from 250 to 500 K, the blue shifts of the frequencies are approximately 0.14, 0.32, and 0.60 THz, respectively. The sensitivities of the three absorption peaks are 0.56, 1.27, and 2.38 GHz/K, respectively. When the Fermi level of the BDS is adjusted from 100 to 30 meV, the device can be switched to a broadband absorber with a bandwidth of 0.70 THz. By adjusting the temperature of STO from 250 to 500 K, the central frequency shifts from 1.40 to 1.79 THz, and the bandwidth broadens from 0.70 to 0.96 THz. The sensitivity of the central frequency is 1.57 GHz/K. The absorber also has a wide range of potential applications in multifunctional tunable devices, such as temperature sensors, stealth equipment, and filters.

A Novel Multi-view Bi-clustering method for identifying abnormal Co-occurrence medical visit behaviors.

Abnormal co-occurrence medical visit behavior is a form of medical insurance fraud. Specifically, an organized gang of fraudsters hold multiple medical insurance cards and purchase similar drugs frequently at the same time and the same location in order to siphon off medical insurance funds. Conventional identification methods to identify such behaviors rely mainly on manual auditing, making it difficult to satisfy the needs of identifying the small number of fraudulent behaviors in the large-scale medical data. On the other hand, the existing single-view bi-clustering algorithms only consider the features of the time-location dimension while neglecting the similarities in prescriptions and neglecting the fact that fraudsters may belong to multiple gangs. Therefore, in this paper, we present a multi-view bi-clustering method for identifying abnormal co-occurrence medical visit behavioral patterns, which performs cluster analysis simultaneously on the large-scale, complex and diverse visiting record dimension and prescription dimension to identify bi-clusters with similar time-location features. The proposed method constructs a matrix view of patients and visit records as well as a matrix view of patients and prescriptions, while decomposing multiple data matrices into sparse row and column vectors to obtain a consistent patient population across views. Subsequently the proposed method identifies the corresponding abnormal co-occurrence medical visit behavior and may greatly facilitate the safe operations and the sustainability of medical insurance funds. The experimental results show that our proposed method leads to more efficient and more accurate identifications of abnormal co-occurrence medical visit behavior, demonstrating its high efficiency and effectiveness.

Multifunctional terahertz absorber based on the Dirac semimetal and vanadium dioxide.

In this paper, a multifunctional terahertz (THz) absorber based on Dirac semimetal and vanadium dioxide (V O 2) is proposed. By modulating the temperature of V O 2, the absorber can be switched between the narrow band and wide band. When V O 2 is in the metallic state, the absorber has a broadband absorption effect with a bandwidth of approximately 4 THz. It has the advantages of insensitivity to polarization and wide-angle absorption. When V O 2 is in the insulating state, the absorber has two absorption peaks with absorptivity exceeding 90% and sensitivities of 297.7 and 402 GHz/RIU, and thus can be used as a highly sensitive sensor for cell detection. When the Fermi level of the Dirac semimetal is changed, the absorption characteristics can be modulated. The absorber has broad application prospects in multifunctional modulated devices.

High-performance dual-tunable terahertz absorber based on strontium titanate and bulk Dirac semimetal for temperature sensing and switching function.

In this study, a perfect metamaterial absorber based on strontium titanate and bulk Dirac semimetals is proposed. When the temperature of strontium titanate was 300K, the dual-band absorptions were 99.74% and 99.99% at 1.227 and 1.552 THz, respectively. The sensitivities based on a transverse magnetic (TM) wave were 0.95 and 1.22 GHz/K; the sensitivity based on a transverse electric (TE) wave was 0.76 GHz/K. The TE and TM waves were modulated by inserting a bulk Dirac semimetal between the concave and convex devices. The modulation depth of the TE wave was 97.9% at 1.1 THz; the extinction ratio was 16.9 dB. The modulation depth of the TE wave at 1.435 THz was 95.9%; the extinction ratio was 13.89 dB. The TM wave modulation depth at 1.552 THz was 95.9%; the extinction ratio was 13.98 dB. Irrespective of a TE or TM wave, the terahertz absorber has good switching and temperature-sensing performance based on strontium titanate and bulk Dirac semimetals as well as broad application prospects in temperature sensing and switching devices.

Optimization Design of Surface Wave Electromagnetic Acoustic Transducers Based on Simulation Analysis and Orthogonal Test Method.

The energy conversion of electromagnetic acoustic transducers (EMATs) is typically lower, which seriously restricts the application of EMATs in the field of non-destructive testing and evaluation. In this work, parameters of surface wave EMATs, including structural parameters and electrical parameters, are investigated using the orthogonal test method to improve the transducer's energy conversion efficiency. Based on the established finite element 2-D model of EMATs, the amplitude of the displacement components at the observation point of a plate is the optimization objective to be maximized with five parameters pertaining to the magnets, meander-line coils, and excitation signal as design variables. Results show that the signal amplitude of EMATs is 3.48 times on in-plane and 3.49 times on out-of-plane, respectively, compared with the original model. Furthermore, a new material (amorphous nanocrystalline material of type 1K107) is applied to optimize the magnetic circuit of EMATs and enhance the eddy current in an aluminum plate to increase the signal amplitude. Finally, the signal amplitudes obtained from the three types of models, that is, the original one, the optimization one after an orthogonal test, and the optimization one with the addition of magnetic concentrators, are analyzed and compared, indicating that the signal amplitude, compared with the original one, is 6.02 times on in-plane and 6.20 times on out-of-plane, respectively.

[Research Progress of Electromagnetic Metasurface Used for Radar Cross Section Reduction in Microwave and Terahertz Wave].

Electromagnetic metasurface with many special electromagnetic properties can be utilized to manipulate electromagnetic wave propagation and reflection. If the metasurfaces were designed for coding, random, phase discontinuities, perfect absorber and so on，they can manipulate the scattering or the reflection of electromagnetic wave and achieve the reduction of the radar cross section(RCS). This paper mainly presents the recent progress concerning the reduction of RCS using non - directional scattering or the absorption characteristic in microwave and terahertz wave. The analysis results show that coding electromagnetic metasurface can disperse the reflection into a variety of direction by designing the specific coding sequences for different elements. The coding metasurface which are composed of different digital elements, and the reflection phase difference of these digital elements is constant in a wide frequency range, and higher bit coding metasurface can flexible manipulate electromagnetic wave. The random electromagnetic metasurface can achieve broadband phase shifter by adjusting the size parameters of array element, and can diffuse characteristic by scattering into random wave of the reflection peaks for metal target. Phase discontinuities metasurface can achieve anomalous or diffuse of wave because the phase distribution is not uniform at the surface. The absorber metasurfaces which are designed reasonably with the physical dimensions of the devices can reduce reflection by absorbing electromagnetic wave energy. So, the electromagnetic metasurfaces have a large potential application for radar stealth, broadband communications, imaging and so on. Finally, we discussed the future development of RCS reduction by using the electromagnetic metasurface. In order to satisfy the needs of practical application, the research of metasurface will continue development in broadband, flexible, large angle and other aspects.

Facile synthesis of porous bimetallic alloyed PdAg nanoflowers supported on reduced graphene oxide for simultaneous detection of ascorbic acid, dopamine, and uric acid.

Porous bimetallic alloyed palladium silver (PdAg) nanoflowers supported on reduced graphene oxide (PdAg NFs/rGO) were prepared via a facile and simple in situ reduction process, with the assistance of cetyltrimethylammonium bromide as a structure directing agent. The as-prepared nanocomposite modified glassy carbon electrode (PdAg NFs/rGO/GCE) showed enhanced catalytic currents and enlarged peak potential separations for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA) as compared to those of PdAg/GCE, rGO/GCE, commercial Pd/C/GCE, and bare GCE. The as-developed sensor can selectively detect AA, DA, and UA with a good anti-interference ability, wide concentration ranges of 1.0 µM-2.1 mM, 0.4-96.0 µM, and 1.0-150.0 µM, respectively, together with low detection limits of 0.057, 0.048, and 0.081 µM (S/N = 3), respectively. For simultaneous detection of AA, DA, and UA, the linear current-concentration responses were observed from 1.0 µM-4.1 mM, 0.05-112.0 µM, and 3.0-186.0 µM, with the detection limits of 0.185, 0.017, and 0.654 µM (S/N = 3), respectively.

Two new 2,3-seco-hopane triterpene derivatives from Megacodon stylophorus and their antiproliferative and antimicrobial activities.

Chemical investigation of the ethanol extract of the whole plant of Megacodon stylophorus led to the isolation and identification of two new seco-hopane triterpenoids, 2,3-seco-22(29)-hopene-2-carboxyl-3-aldehyde (1) and 2,3-seco-4(23),22(29)-hopene-2-carboxyl-3-aldehyde (2), along with 10 known compounds, 3-12. All the isolates were reported from this plant for the first time. The structures of compounds 1 and 2 were determined by detailed analysis of their spectral data including 1D and 2D NMR. In addition, compound 1 was further analyzed by X-ray crystallography. Compounds 1-3 were evaluated for their in vitro anti-proliferative activities on HeLa, MCF-7, and Hep-G2 tumor cell lines. Compound 2 was active against the three cell lines with IC50 values of 3.6, 7.5, and 13.6 µM, respectively, while compound 1 exhibited cytotoxicity on MCF-7 (IC50 14.0 µM) and HeLa (IC50 18.2 µM) cell lines. Antimicrobial activities of compounds 1-2 (minimum inhibitory concentration values in the range of 3.12-12.50 mg/mL) were also observed.

[Research progress in the application of biosensors by using metamaterial in terahertz wave].

In the present paper, the recent progress in terahertz metamaterials-based sensing is reviewed with the principle of metamaterial biosensor,metamaterial substrate, and structure design, respectively. The paper introduces the principle in detail, analyzes the sensitivity of the biosensor with the material and the thickness of the substrate and the structure of metamaterial. The analysis shows that we can enhance the sensitivity and resolution of biosensor by designing specific metamaterial structure, using low dielectric constant and low loss thin substrate, especially many materials have a specific response in the terahertz frequency. So, there is a large potential application for label-free sensing by using the terahertz metamaterials. This paper also presents the future development of THz metamaterial sensors.

Correction: Chen et al. Multifunctional Injectable Hydrogel Loaded with Cerium-Containing Bioactive Glass Nanoparticles for Diabetic Wound Healing. Biomolecules 2021, 11, 702.

The authors would like to replace Figure 4A of the following published paper [...].

Triterpenoid saponins with anti-myocardial ischemia activity from the whole plants of Clematis tangutica.

Four new triterpenoid saponins named clematangosides A-D (1-4) along with six known saponins (5-10) were isolated from the whole plants of Clematis tangutica. Their structures were determined by extensive spectral analysis and chemical evidences. All saponins were evaluated for their protective effects in hypoxia-induced myocardial injury model. Compounds 2-4, 6, and 10 exhibited anti-myocardial ischemia activities with ED50 values in the range of 75.77-127.22 µM.

Norlathyrane diterpenes from the root of Euphorbia kansuensis.

Phytochemical investigation of the EtOH extract obtained from the root of the Euphorbia kansuensis Proch. grown in China resulted in the isolation of two novel norlathyrane diterpenes, named ekanpenoids A and B (1 and 2, resp.). Their structures were established by extensive 1D- and 2D-NMR spectroscopy, as well as other spectra. The isolated diterpenes exhibited potent cytotoxic activities against the HeLa and Hep-G2 cell lines with the IC50 values ranging from 3.6 to 9.7 µg/ml.

Efficacy analysis of virtual reality-based training for activities of daily living and functional task training in stroke patients: A single-subject study.

INTRODUCTION: Virtual reality (VR)-based training for functions such as cognition, upper extremities, balancing, and activities of daily living (ADL) has been used on stroke patients, and its efficacy has been reported. However, no comparison has been made between the efficacy of VR-based training for daily activities that exactly reproduces ADL and functional training. Therefore, this study sought to analyze the difference in independency enhancement of VR-based training for daily activities compared to cognitive and motor functional training. PATIENT CONCERNS AND DIAGNOSIS: This study was conducted on 4 patients who have been diagnosed with stroke and are currently receiving rehabilitation therapy in G hospital located in the city of Gwangju, using A-B-A'-B' design from single-subject experimental designs. INTERVENTIONS: Intervention was performed in 2 ways: application of VR-based training for daily activities after the application of cognitive and motor function training; and application of cognitive and motor function training after the application of VR-based training for daily activities. The Assessment of Motor and Process Skills, Computer Cognitive Screening Assessment System, Box and Block Test, and Grip and Pinch Strength Test were used to measure the changes in the performance of daily activities, cognitive function, and upper extremities function. OUTCOMES: The results confirmed that the performance of daily activities, cognitive function, and upper extremities function was improved after the application of VR-based intervention. In addition, the efficacy of independency enhancement was maximized by the early approach of training for daily activities at the time of VR-based intervention in stroke patients. CONCLUSIONS: VR-based intervention of training for daily activities and functional training can be considered to benefit the improvement of the performance of daily activities, cognitive function, and upper extremities function in stroke patients. In addition, although functional training was also effective in enhancing independency and functional improvement in stroke patients, an early approach to training for ADL based on tasks with objectives was deemed to be more effective.

Development of γ-Al2O3 with oxygen vacancies induced by amorphous structures for photocatalytic reduction of CO2.

Inducing amorphous components into Al2O3 leads to elongation of the Al-O bond and the formation of oxygen vacancies, which makes Al2O3 an independent photocatalyst for CO2 adsorption and reduction. The generation rate of CO can reach 36.5 µmol g-1 h-1, which is 6.5 times that of P25 TiO2.

[Application of clinical pathways in children with Rotavirus enteritis].

OBJECTIVE: Clinical pathways are standardized, multidisciplinary, integrated management plans. This study aimed to evaluate the efficacy of clinical pathways in children with Rotavirus enteritis. METHODS: Seventy-one children with Rotavirus enteritis were treated according to the clinical pathways. Seventy-five children with Rotavirus enteritis who received routine therapy and nursing interventions served as the control group. The clinical efficacies were compared between the two groups. RESULTS: The average hospitalization duration was shortened, the hospitalization costs were reduced and the parents' satisfaction rate increased in the observed group compared with the control group (P<0.05). CONCLUSIONS: The use of clinical pathways may decrease the hospitalization duration and costs and improve the quality of nursing care and the parents' satisfaction rate in children with Rotavirus enteritis.

[Percutaneous endoscopic translaminar lumbar interbody fusion for the treatment of L5S1 intervertebral disc herniation].

OBJECTIVE: To observe the effeicacy and safety of percutaneous endoscopic translaminar lumbar interbody fusion (PE-TLIF) in the treatment of L5S1 intervertebral disc herniation. METHODS: The clinical data of 37 patients with L5S1 intervertebral disc herniation underwent PE-TLIF from January 2018 to December 2019 were retrospectively analyzed. There were 16 males and 21 females, aged from 30 to 68 years old, with a mean of (45.62±13.57) years;body mass index was from 19.5 to 28.8 kg/m2, with a mean of (24.33±3.51) kg/m2;the course of disease was from 18 to 48 months, with a mean of (27.18±6.65) months. Operation time, intraoperative blood loss, postoperative drainage and complication rate were recorded; visual analogue scale(VAS), Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index(ODI) before operation, 1 week, 6 months, 1 year after operation were observed. RESULTS: The operation time ranged from 78 to 171 min, with a mean of (120.74±41.19) min;intraoperative blood loss ranged from 61 to 102 ml, with a mean of (85.26±25.44) ml;and postoperative drainage ranged from 35 to 98 ml, with a mean of (40.75±12.17) ml. Complications occurred in 8 patients, including 2 cases of nerve injury, 4 cases of pain aggravated, 1 case of internal fixation loosening, and 1 case of intervertebral space nonfusion. The VAS, JOA score and ODI significantly improved after 1 week, 6 months, and 1 year after operation (P<0.05). CONCLUSION: PE-TLIF for the treatment of L5S1 intervertebral disc herniation has the advantages of less intraoperative blood loss, less trauma, and satisfactory short-term curative effect. It can effectively improve the symptoms of patients. However, the incidence of complications in the actual clinical practice is frequent, and surgical indications need to be strictly grasped.

Multifunctional Injectable Hydrogel Loaded with Cerium-Containing Bioactive Glass Nanoparticles for Diabetic Wound Healing.

Diabetic foot wound healing is a major clinical problem due to impaired angiogenesis and bacterial infection. Therefore, an effective regenerative dressing is desiderated with the function of promoting revascularization and anti-bacteria. Herein, a multifunctional injectable composite hydrogel was prepared by incorporation of the cerium-containing bioactive glass (Ce-BG) into Gelatin methacryloyl (GelMA) hydrogel. The Ce-BG was synthesized by combining sol-gel method with template method, which maintained spherical shape, chemical structure and phase constitution of bioactive glass (BG). The Ce-BG/GelMA hydrogels had good cytocompatibility, promoted endothelial cells migration and tube formation by releasing Si ion. In vitro antibacterial tests showed that 5 mol % CeO2-containing bioactive glass/GelMA (5/G) composite hydrogel exhibited excellent antibacterial properties. In vivo study demonstrated that the 5/G hydrogel could significantly improve wound healing in diabetic rats by accelerating the formation of granulation tissue, collagen deposition and angiogenesis. All in all, these results indicate that the 5/G hydrogel could enhance diabetic wound healing. Therefore, the development of multifunctional materials with antibacterial and angiogenic functions is of great significance to promote the repair of diabetic wound healing.

In vitro study on influence of nano particles of CuO on CA1 pyramidal neurons of rat hippocampus potassium currents.

The effects of nano particles of CuO on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus using the whole-cell patch-clamp techniques. Nano particles of CuO had small effects on transient outward potassium current (I(A), no statistical significance) and mainly inhibited delayed rectifier potassium current (I(K)) in the concentration of 5 x 10(-5) g/mL. Nano particles of CuO didn't shift the steady-state activation curve of I(K) and I(A) but negatively shifted the inactivation curve of I(K). The effects on inactivation curve of I(A) had no statistical significance. These results suggested that blockades of K+ currents by nano particles of CuO could be preferential for I(k) for the first time. This may interfere with the normal function of nerve cells.

[Study of CD4+ CD25+ regulatory T cells and expression of Foxp3 mRNA in bronchiolitis and glucocorticoid regulation].

OBJECTIVE: To explore the pathogenesis of respiratory syncytial viruses (RSV) bronchiolitis and its treatment with glucocorticoids. METHODS: The pediatric patients with RSV bronchiolitis were divided into an atopic group (n = 50) and a non-atopic group (n = 50) based on whether there were IgE elevation, eczema and dermatitis. Another 25 normal subjects were chosen as a control group. Divided into mild, medium and severe groups, they were finally randomly divided into hormone (dexamethasone) and non-hormone groups. The proportion of CD4+ CD25+ regulatory T cells (Treg) and the expression of Foxp3 mRNA were tested by flow cytometry and RT-PCR retrospectively. RESULTS: The proportion of CD4+ CD25+ Treg and the Foxp3 mRNA expression in the control, non-atopic, and atopic groups reached (10.5 +/- 1.6)% and 0.34 +/- 0.11, (8.8 +/- 2.2)% and 0.26 +/- 0.08, (7.6 +/- 1.8)% and 0.21 +/- 0.09, respectively. There were significant differences among these groups (all P < 0.05). The mild, medium and severe bronchiolitis groups reached (9.7 +/- 1.6)% and 0.28 +/- 0.08, (7.8 +/- 2.1)% and 0.24 +/- 0.06, (6.7 +/- 1.3)% and 0.20 +/- 0.07 respectively (all P < 0.05). The proportion of CD4+ CD25+ Treg and the expression of Foxp3 showed significantly negative correlations with severity (r = -0.62, -0.71, both P < 0.01). That is, they correlated with the severity of disease. The proportion of the CD4+ CD25+ Treg and the expression of Foxp3 mRNA of the hormone group were higher than those of the non-hormone group [(9.5 +/- 2.1)% and 0.33 +/- 0.10 vs (8.5 +/- 1.8)% and 0.27 +/- 0.12, P < 0.05 and < 0.01] respectively. CONCLUSION: CD4+ CD25+ Treg and Foxp3 mRNA are involved in the inflammation of bronchiolitis. And the levels of CD4+ CD25+ Treg and Foxp3 mRNA level is an objective indicator of the severity of RSV bronchiolitis. The effect of glucocorticoids upon RSV bronchiolitis may be in part due to the direct enhancement of production and functions of CD4+ CD25+ Treg and Foxp3 mRNA.