Construction and validation of a perioperative concomitant lower extremity deep vein thrombosis line graph model in patients with aneurysmal subarachnoid hemorrhage.

Background: To develop and validate a nomogram for predicting the probability of deep venous thrombosis (DVT) in patients with aneurysmal subarachnoid hemorrhage (aSAH) during the perioperative period, using clinical features and readily available biochemical parameters. Methods: The least absolute shrinkage and selection operator (LASSO) regression technique was employed for data dimensionality reduction and selection of predictive factors. A multivariable logistic regression analysis was conducted to establish a predictive model and nomogram for post-aSAH DVT. The discriminative ability of the model was determined by calculating the area under the curve (AUC). Results: A total of 358 aSAH patients were included in the study, with an overall incidence of DVT of 20.9%. LASSO regression identified four variables, including age, modified Fisher grade, total length of hospital stay, and anticoagulation therapy, as highly predictive factors for post-aSAH DVT. The patients were randomly divided into a modeling group and a validation group in a 6:4 ratio to construct the nomogram. The AUCs of the modeling and validation groups were 0.8511 (95% CI, 0.7922-0.9099) and 0.8633 (95% CI, 0.7968-0.9298), respectively. Conclusions: The developed nomogram exhibits good accuracy, discriminative ability, and clinical utility in predicting DVT, aiding clinicians in identifying high-risk individuals and implementing appropriate preventive and treatment measures.

Design and experimental realization of triple-band electromagnetically induced transparency terahertz metamaterials employing two big-bright modes for sensing applications.

Multi-band electromagnetically induced transparency (EIT) effects have attracted widespread attention due to their great application prospects. However, their realization is mainly based on the coupling of multiple sub-resonators that typically exceed the number of transparency peaks, resulting in complex structural designs and cumbersome preparation procedures. This paper reports a simple design of a terahertz metamaterial that can produce the triple-band EIT effect using two "big-bright" mode coupling of two sub-resonators. The design adopts the classical two-layer structure. A U-shaped split-ring resonator and a fork-shaped resonator form a periodic array on the surface of the flexible organic polymer material. Three transparency peaks around 0.59 THz, 1.07 THz, and 1.34 THz are experimentally realized, and their formation mechanisms are explored. Furthermore, the triple-band EIT metamaterial was prepared by the photolithography technology and characterized by terahertz time-domain spectroscopy. Theoretical simulation results agree well with experimental results. Sensing characteristics and slow light effects of the terahertz metamaterial are further discussed experimentally. The proposed triple-band EIT metamaterial having excellent properties, including thin size, good flexibility, simple and compact structure, and high sensing sensitivity, could provide guidance for the subsequent design and implementation of multifunctional multi-band EIT metamaterials.

Effects of long-term fertilization patterns on bacterial community structure and soil nutrients in dryland of yellow soil.

Understanding the responses of soil bacterial community to long-term fertilization in dryland of yellow soil could provide theoretical basis for establishing scientific fertilization system and cultivating healthy soil. Based on a 25-year long-term fertilization experiment on yellow soil, we collected soil samples from 0-20 cm layer under different fertilization treatments: no fertilization (CK), balanced application of N, P and K fertilizers (NPK), single application of organic fertilizer (M), combined application of constant organic and inorganic fertilizer (MNPK), and 1/2 organic fertilizer instead of 1/2 chemical fertilizer (MNP). Illumina MiSeq high-throughput sequencing technology was used to examine the effects of different fertilization patterns on soil bacterial community structure and soil nutrient content. The main driving factors of soil bacterial community were explored. The results showed that soil pH and organic matter content under treatments with organic fertilizer increased by 11.4%-13.5% and 28.8%-52.0%, respectively, compared to that under NPK treatment. Long-term fertilization did not affect soil bacterial α diversity, but significantly affected soil bacterial ß diversity. Compared with CK and NPK treatment, treatments of M, MNP, and MNPK significantly changed soil bacterial community structure, and increased the relative abundance of Fusobacteria and Anaerobes. Four fertilization treatments increased the relative abundance of Bacteroidetes, and decreased the relative abundance of Actinomyces and Campylobacter, compared to CK. Soil pH was the most important factor affecting soil bacterial community structure. Fertilization-stimulated rare microbial taxa (Pumilomyces and Anaerobes) were more sensitive to changes in different environmental factors and were the main drivers of the formation of community versatility. In conclusion, organic fertilizer improved soil properties and fertility and changed soil bacterial community structure, which are conducive to cultivating healthy soil.

Triple-Band and Ultra-Broadband Switchable Terahertz Meta-Material Absorbers Based on the Hybrid Structures of Vanadium Dioxide and Metallic Patterned Resonators.

A bifunctional terahertz meta-material absorber with three layers is designed. The surface of the bifunctional meta-material absorber is a periodically patterned array composed of hybrid structures of vanadium dioxide (VO2) and metallic resonators; the middle layer is a nondestructive TOPAS film, and the bottom layer is a continuous metallic plane. Utilizing the phase-transition property of VO2, the responses of the meta-material absorber could be dynamically switched between triple-band absorption and ultra-broadband absorption. When VO2 is in the metallic state, an ultra-broadband absorption covering the bandwidth of 6.62 THz is achieved over the range from 4.71 THz to 11.33 THz. When VO2 is in the di-electric state, three absorption peaks resonated at 10.57 THz, 12.68 THz, and 13.91 THz. The physical mechanisms of the bifunctional meta-material absorber were explored by analyzing their near-field distributions. The effects of varying structural parameters on triple-band and ultra-broadband absorption were investigated. It is revealed that by optimizing the structure parameters, the number of absorption peaks could be increased for a certain sacrifice of absorption bandwidth. FDTD Solutions and CST Microwave Studio were used to simulate the data of the absorber, and similar results were obtained.

Influence of long-term fertilization on soil aggregates stability and organic carbon occurrence characteristics in karst yellow soil of Southwest China.

Current research has long focused on soil organic carbon and soil aggregates stability. However, the effects of different long-term fertilization on the composition of yellow soil aggregates and the characteristics of the occurrence of organic carbon in the karst region of Southwest China are still unclear. Based on a 25-year long-term located experiment on yellow soil, soil samples from the 0-20 cm soil layer were collected and treated with different fertilizers (CK: unfertilized control; NPK: chemical fertilizer; 1/4 M + 3/4 NP: 25% chemical fertilizer replaced by 25% organic fertilizer; 1/2 M + 1/2 NP: 50% chemical fertilizer replaced by organic fertilizer; and M: organic fertilizer). In water-stable aggregates, soil aggregates stability, total organic carbon (TOC), easily oxidized organic carbon (EOC), carbon preservation capacity (CPC), and carbon pool management index (CPMI) were analyzed. The findings demonstrated that the order of the average weight diameter (MWD), geometric mean diameter (GWD), and macro-aggregate content (R0.25) of stable water aggregates was M > CK > 1/2M +1/2NP > 1/4M +3/4NP> NPK. The MWD, GWD, and R0.25 of NPK treatment significantly decreased by 32.6%, 43.2%, and 7.0 percentage points, respectively, compared to CK treatment. The order of TOC and EOC content in aggregates of different particle sizes was M > 1/2M +1/2NP > 1/4M +3/4NP> CK > NPK, and it increased as the rate of organic fertilizer increased. In macro-aggregates and bulk soil, the CPC of TOC (TOPC) and EOC (EOPC), as well as CPMI, were arranged as M > 1/2M +1/2NP > 1/4M +3/4NP> CK > NPK, but the opposite was true for micro-aggregates. In bulk soil treated with organic fertilizer, the TOPC, EOPC, and CPMI significantly increased by 27.4%-53.8%, 29.7%-78.1%, 29.7-82.2 percentage points, respectively, compared to NPK treatment. Redundancy analysis and stepwise regression analysis show that TOC was the main physical and chemical factor affecting the aggregates stability, and the TOPC in micro-aggregates has the most direct impact. In conclusion, the primary cause of the decrease in SOC caused by the long-term application of chemical fertilizer was the loss of organic carbon in macro-aggregates. An essential method to increase soil nutrient supply and improve yellow soil productivity was to apply an organic fertilizer to increase aggregates stability, storage and activity of SOC in macro-aggregates.

Stellate ganglion block alleviates postoperative cognitive dysfunction via inhibiting TLR4/NF-κB signaling pathway.

Postoperative cognitive dysfunction (POCD) is common in aged patients after major surgery and is associated with increased risk of long-term morbidity and mortality. However, the underlying mechanism remains largely unknown and the clinical management of POCD is still controversial. Stellate ganglion block (SGB) is a clinical treatment for nerve injuries and circulatory issues. Recent evidence has identified the benefits of SGB in promoting learning and memory. We thus hypothesize that SGB could be effective in improving cognitive function after surgery. In present study, we established POCD model in aged rats via partial liver resection surgery. We found that the development of POCD was associated with the activation of toll-like receptor 4/nuclear factor kapa-B (TLR4/NF-κB) signaling pathway in the microglia in dorsal hippocampus, which induced the production of pro-inflammatory mediators (TNF-α, IL-1ß, IL-6) and promoted neuroinflammation. More importantly, we showed evidence that preoperative treatment with SGB could inhibit microglial activation, suppress TLR4/NF-κB-mediated neuroinflammation and effectively attenuate cognitive decline after the surgery. Our study suggested that SGB may serve as a novel treatment to prevent POCD in elderly patients. As SGB is safe procedure widely used in clinic, our findings can be easily translated into clinical practice and benefit more patients.

Modeling and Characterization of Surface Discharges in Insulating Material for Spacers: Electrode Shape, Discharge Mode, and Revision of the Creepage Concept.

In the design of MV AC and DC spacers, the predominant factors are surface and interface conditions. Design is generally carried out on specifications and standards which are based on long-term experience and lab testing. However, the diffusion of power electronics with a trend to increase electric field, switching frequency, and rise time to achieve higher power density calls for an innovative, global approach to optimized insulation system design. A new methodology, based on field simulation, discharge modeling, and partial discharge inception measurements, called the three-leg approach, can form the basis to optimize insulation design for any type of supply voltage waveform. This paper focuses on the influence of the type of electrode on the inception and phenomenology of surface discharges and, as a consequence, on the interpretation of the results used for application of the three-leg approach. It is demonstrated that a typical electrode system used for insulating material testing can generate both gas and surface discharges at the triple point, when the electrodes have a smooth profile that is used to avoid corona or flashover. Hence, testing partial discharge may not provide a straightforward indication of the surface discharge inception and, thus, be partially misleading for insulation design. Another takeover is that such analysis must benefit from PD testing tools endowed with analytics able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona, since design and remedy actions can be taken, and adequate insulating materials developed, only knowing the type of source generating PD. Hence, testing partial discharge may not provide a straightforward indication of surface discharge inception and, thus, be partially misleading for insulation design. In addition to the importance of the three-leg approach to favor reliable and optimized design of insulation systems, there is a clear need to have a PD testing tool endowed with analytics. It should preferably be able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona.

Application of meridian and acupoint diagnosis of three yin meridians of foot in the treatment for gynecological diseases with acupuncture and moxibustion / 中国针灸

With three representative types of gynecological diseases (dysmenorrhea, pelvic inflammation, polycystic ovary syndrome) as examples, the application methods of meridian and acupoint diagnosis for gynecological diseases treated with acupuncture and moxibustion are discussed. During clinical diagnosis and treatment, it is recommended to examine the patient's leg segment along the three yin meridians of foot, aiming to explore the positive reactions of the meridians and acupoints (color, shape, skin temperature, sensory abnormalities, etc.). Acupuncture and moxibustion treatment at this positive reaction place can improve the clinical efficacy. Meridian and acupoint diagnosis could provide basis for meridian syndrome differentiation, thus guiding the selection of acupoint prescriptions; it is also helpful to clarify the deficiency, excess, cold and heat of the disease nature, thus guiding the selection of acupuncture and moxibustion methods. In addition, it is an auxiliary method to estimate the prognosis and outcome of the disease.

Acupuncture for prevention of moderate to severe seasonal allergic rhinitis: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the clinical efficacy of acupuncture for prevention of moderate to severe seasonal allergic rhinitis.@*METHODS@#A total of 105 patients with moderate to severe seasonal allergic rhinitis were randomly divided into an observation group (53 cases, 3 cases dropped off) and a control group (52 cases, 4 cases dropped off). The patients in the observation group were treated with acupuncture at Yintang (GV 24+), Yingxiang (LI 20), Hegu (LI 4), Zusanli (ST 36), Fengchi (GB 20), Feishu (BL 13), etc. 4 weeks before the seizure period, once every other day, 3 times a week for 4 weeks. The patients in the control group were not given any intervention before the seizure period. Emergency drugs can be given appropriately during the seizure period in both groups. After seizure period, the seizure rate was recorded in the two groups; before treatment and on week 1, 2, 4, 6 of seizure period after treatment, the rhinoconjunctivitis quality of life questionnaire (RQLQ) score and total nasal symptom score (TNSS) were observed in the two groups; the rescue medication score (RMS) was recorded on week 1-6 of seizure period in the two groups.@*RESULTS@#The seizure rate of the observation group was 84.0% (42/50), which was lower than 100.0% (48/48) in the control group (P<0.05). After treatment, the scores of RQLQ and TNSS at each time point of seizure period were decreased compared with before treatment in the observation group (P<0.01), which were lower than the control group (P<0.01). The RMS score at each time point of seizure period in the observation group was lower than the control group (P<0.05, P<0.01).@*CONCLUSION@#Acupuncture can reduce the incidence of moderate to severe seasonal allergic rhinitis, relieve the symptoms, improve the quality of life and reduce the use of emergency drugs.

Expression of Key Enzymes in Glucose Metabolism in Chronic Mountain Sickness and Its Correlation with Phenotype / 中国实验血液学杂志

OBJECTIVE@#To explore the pathogenesis of erythrocytosis by detecting the key enzymes of glucose metabolism and glucose transporter in bone marrow erythrocytes of chronic mountain sickness (CMS), and analyzing its correlation with hemoglobin.@*METHODS@#Twenty CMS patients hospitalized in Qinghai Provincial People's Hospital from January 2019 to December 2020 were selected as CMS group. Twenty males with leukocyte count > 3.5×109/L who had accepted bone marrow aspiration and had normal result were taken as control group. The mRNA and protein expression of key enzymes and glucose transporter in glucose metabolism in bone marrow CD71+ erythrocytes were detected by real time qPCR and Western blot, respectively. Glucose, lactic acid and 2,3-diphosphoglycerate in the bone marrow supernatant and serum were tested by ELISA. The mRNA and protein expression of key enzymes and glucose transporter, glucose, lactic acid and 2,3-diphosphoglycerate of the two groups were compared. Pearson correlation was used to analyze the correlation between key enzymes, glucose transporter in glucose metabolism in bone marrow CD71+ erythrocytes and hemoglobin.@*RESULTS@#The expression of HK2, GLUT1 and GLUT2 mRNA in the CMS group were higher than those in the control group (P<0.001), while the expression of HK1, OGDH and COX5B mRNA were not different. The expression of HK2, GLUT1 and GLUT2 protein in the CMS group were higher than those in the control group (P<0.05). The levels of glucose and lactic acid in the bone marrow supernatant and serum in the CMS group were not different from those in the control group, while the level of 2,3-diphosphoglycerate was higher (P<0.001). Both HK2 and GLUT2 proteins were positively correlated with hemoglobin (r=0.511, 0.717).@*CONCLUSION@#CMS patients may increase glycolysis by increasing the expression of HK2, and promote the utilization of glucose through high expression of GLUT1 and GLUT2 to meet the need of energy supply.

Nurse-to-nurse horizontal violence in Chinese hospitals and the protective role of head nurse's caring and nurses' group behaviour on it: A cross-sectional study.

AIMS: This study aimed to analyse the prevalence of nurse-to-nurse horizontal violence in Chinese hospitals and examine the effects of head nurse's caring and nurse's group behaviour on horizontal violence. BACKGROUND: Horizontal violence is a serious global problem affecting the nursing profession, but little is known of the issue in Chinese hospitals. Increasing evidence has showed that leadership and group factors are important in facilitating horizontal violence. Whether the head nurse's caring and group behaviour perceived by nurses has protective effects against horizontal violence remains unclear. METHODS: A cross-sectional online-based questionnaire study was performed in seven general hospitals in Hubei Province, China. Data related to the demographic information, horizontal violence, head nurse's caring and group behaviour were collected. Descriptive analyses, chi-squared tests and logistic regression were used for data analysis. RESULTS: In total, 1942 valid questionnaires were collected, with a 92.70% effective response rate (1942/2095). Of those, 59.1% (1148/1942) of respondents had experienced horizontal violence at least once in the previous 6 months. Covert negative behaviours were more frequently reported. Compared with the low level, moderate and high levels of the head nurse's caring showed a lower risk of horizontal violence (odds ratio [OR] = 0.400, p < .001; OR = 0.128, p < .001); moderate and high levels of group behaviour also showed a reduced risk (OR = 0.601, p < .001; OR = 0.221, p < .001). CONCLUSION: Horizontal violence is common among Chinese nurses. The head nurse's caring and maintaining a good climate of nurses' group behaviours could serve as protective factors for preventing horizontal violence. IMPLICATIONS FOR NURSING MANAGEMENT: This study helps nursing managers identify which specific negative behaviours occur frequently and require special attention. It suggests that nursing managers attach importance to improving their caring ability towards nurses and to creating an amicable climate of group behaviour to buffer against horizontal violence.

Consideration on the construction of acupuncture and moxibustion clinical diagnosis and treatment system with the core of "differentiation of disease location": taking "treatment" of Science of Acupuncture and Moxibustion as an example / 中国针灸

Based on the difference between disease and syndrome differentiation of acupuncture and moxibustion and each department of TCM, i.e. internal medicine, external medicine, gynecology and pediatrics, it is believed that "differentiation of disease location" is the key of disease and syndrome differentiation of acupuncture and moxibustion. According to the disease location, in the section "treatment" of Science of Acupuncture and Moxibustion, the disorders/illness are classified as zangfu disorder, disorders of limbs and meridians, dermatological disorder, ophthalmological and otorhinolaryngological disorder, gynecological disorder, as well as qi, blood and body fluid disorder. Besides, the rules of disease and syndrome differentiation, as well as treatment characteristics of each category are explained separately. It is considered that the clinical diagnosis and treatment system of acupuncture and moxibustion should be constructed by focusing on "differentiation of disease location".

Wave-thermal effect of a temperature-tunable terahertz absorber.

Heat-sensitive materials have great applications in sensor, detector, and tunable photoelectric devices. However, the wave-thermal effect of the heat-sensitive material is rarely been investigated in the THz range. Here, we propose the incorporation of heat-sensitive material (strontium titanate (STO)) within a THz absorber. The simulated results show that the absorptance and frequency can be dynamically controlled by the temperature of STO. Because the absorbed THz waves are finally converted into heat, then we research the theoretical mechanism of heat generation. Theoretical analysis shows that there are two reasons for the temperature rise: surface plasmon polariton (SPP) and ohmic loss of gold patch; Electromagnetic energy consumption inside the loss materials. To verify the theory, finally, we use COMSOL Multiphysics to research the nanosecond wave-thermal effect. The transient temperature of the wave-thermal effect is calculated quantitatively. The quantitative prediction of temperature variation can provide good guidance for thermal regulation and wave-thermally tunable THz devices.

A Partial Discharge Study of Medium-Voltage Motor Winding Insulation Under Two-Level Voltage Pulses With High Dv/Dt.

Medium-voltage (e.g., 10 kV rated) silicon carbide (SiC) devices have great potentials in medium-voltage variable speed drives. But their high switching dv/dt can increase the voltage stress on motor windings and cause partial discharges. This paper presents a partial discharge study of a medium-voltage form-wound winding under two-level square-wave voltage pulses. A 10 kV SiC device-based test platform is built to generate voltage pulses with high dv/dt. A three-step test approach is proposed and employed to systematically investigate the effects of various voltage parameters on partial discharges. These include voltage rise/fall time, voltage pulse width, pulse repetitive rate, duty ratio, voltage polarity, fundamental frequency, and modulation index. Partial discharge inception voltages (PDIVs) and repetitive partial discharge inception voltages (RPDIVs) of the sample are measured with varied voltage parameters. Test results show that voltage rise/fall time is a major affecting factor which reduces PDIVs of the winding sample by 6.5% when it decreases from 800 ns to 100 ns. Based on test results, a hypothetical partial discharge mechanism is presented to explain the effects of fast voltage rise/fall edges. An empirical equation is also derived to estimate PDIVs of a winding sample under various voltage rise/fall time and pulse width conditions.

Clinical Performance of the Xpert® CT/NG Test for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae: A Multicenter Evaluation in Chinese Urban Hospitals.

Background: We aimed to evaluate the clinical performance of the GeneXpert® (Xpert) CT/NG assay for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) using urine and cervical swabs collected from patients in China. Methods: This study was conducted from September 2016 to September 2018 in three Chinese urban hospitals. The results from the Xpert CT/NG test were compared to those from the Roche cobas® 4800 CT/NG test. Discordant results were confirmed by DNA sequence analysis. Results: In this study, 619 first void urine (FVU) specimens and 1,042 cervical swab specimens were included in the final dataset. There were no statistical differences between the results of the two tests for the detection of CT/NG in urine samples (p > 0.05), while a statistical difference was found in cervical swabs (p < 0.05). For CT detection, the sensitivity and specificity of the Xpert test were 100.0% (95%CI = 96.8-99.9) and 98.3% (95%CI = 96.6-99.2) for urine samples and 99.4% (95%CI = 96.5-100.0) and 98.6% (95%CI 97.5-99.2) for cervical swabs, respectively. For NG detection, the sensitivity and specificity of the Xpert test were 99.2% (95%CI = 94.9-100.0) and 100.0% (95%CI = 99.0-100.0) for urine and 100% (95%CI = 92.8-100.0) and 99.7% (95%CI = 99.0-99.9) for cervical swabs, respectively. Conclusion: The Xpert CT/NG test exhibited high sensitivity and specificity in the detection of CT and NG in both urine and cervical samples when compared to the reference results. The 90-min turnaround time for CT and NG detection at the point of care using Xpert may enable patients to receive treatment promptly.

Clinical observation of herb-separated moxibustion on segmental conception vessel combined with low-frequency TEAS for asthenospermia and oligospermia / 中国针灸

OBJECTIVE@#To observe the clinical effect of herb-separated moxibustion on segmental conception vessel combined with low-frequency transcutaneous electrical acupoint stimulation (TEAS) for asthenospermia and oligospermia.@*METHODS@#A total of 105 patients with asthenospermia and oligospermia were randomly divided into a combination group, a TEAS group and a medication group, 35 cases in each one. In the medication group, vitamin E capsules, coenzyme Q10 capsules，@*RESULTS@#Compared before treatment, except for the sperm morphology 2 months into treatment in the medication group, the semen routine indexes 2, 3 months into treatment were improved in the 3 groups (@*CONCLUSION@#Herb-separated moxibustion on segmental conception vessel combined with low-frequency TEAS can improve semen routine, reduce sperm oxidative stress damage for patients with asthenospermia and oligospermia, and the clinical efficacy is better than the medication and TEAS.

Present situation, prospects and suggestions of acupuncture-moxibustion in Namibia / 中国针灸

This article introduces the present development status, medical insurance charges, publicity and influence, legislation and practice of acupuncture-moxibustion in Namibia, and proposes some countermeasures for the current problems in the development of acupuncture-moxibustion in Namibia. Namibia has passed legislation of acupuncture-moxibustion and incorporated acupuncture-moxibustion into the medical insurance system in March 2020. The acupuncture-moxibustion will enter the fast track of development, but the acupuncture-moxibustion education, training and cooperation, talent cultivation mode, reimbursement scope of medical insurance, and standardization construction still need to be steadily improved and strengthened.

Wideband and polarization-insensitive metamaterial absorber with loading lumped resistors.

IWe have designed, simulated, and experimentally tested a broadband metamaterial absorber loaded with lumped resistors in the microwave range. Compared with an electric resonator structure absorber, the composite absorber loaded with lumped resistors has stronger absorptivity over an extremely extended bandwidth. The simulated results show that an effective absorption bandwidth covers from 7.12 to 8.61 GHz with the absorption rate more than 90% under normal incidence. For oblique incidence, the proposed absorber displays an absorption rate above 90% from 7.55 to 8.61 GHz when the incident angle is below 35° for the transverse electric polarization. About the transverse magnetic polarization, the absorber displays larger than 90% absorptance from 7.24 to 8.61 GHz when the incident angle is below 70°. During the entire design process, the absorber structure is fabricated and measured. The measured results show that the absorptivity is above 90% in the frequency range of 6.78-7.65 GHz and 8.20-9.31 GHz under normal incidence. Furthermore, the absorption mechanism and absorption properties are further researched.

A thermally and electrically dual-tunable absorber based on Dirac semimetal and strontium titanate.

In this paper, we proposed a bi-tunable terahertz (THz) metamaterial absorber based on bulk Dirac semimetal (BDS) and strontium titanate (STO). When the values of Fermi energy EF and temperature (T) are equal to 40 meV and 300 K, the simulation result shows that the absorption frequency is centered at 3.69 THz with nearly 100% absorption rates. Interestingly, by adjusting the Fermi energy EF of the BDS pattern from 10 to 80 meV, the peak absorptivity can be continuously tuned from 70% to 99.9%, and the absorption frequency point shifts from 3.265 to 4.82 THz. Meanwhile, when the temperature of the STO metamaterial changes from 200 to 300 K, the absorption frequency point can be dynamically controlled from 2.665 to 3.69 THz with a fixed amplitude. When Fermi energy EF of the BDS and temperature T of STO were varied, the relative impedances of the absorber were investigated. Furthermore, the electric field and power loss density distributions were also examined to further explain the related physical mechanism. Owing to its symmetrical structure, the proposed absorber demonstrates intensity polarization-independent characteristics and can maintain stable absorption with a large range of incident angles. The proposed absorber may be used in various devices such as detectors, selective heat emitters, and smart devices.

Broadband dynamically tunable terahertz absorber based on a Dirac semimetal.

In this paper, we propose a broadband tunable metamaterial absorber in the terahertz (THz) region. The absorber comprises a Dirac semimetal film, a dielectric layer, and a gold ground plane. Numerical results show that the absorptivity remains above 90% in the range from 5.7 THz to 8.4 THz when the Fermi level is 65 meV. By varying the Fermi energy of the Dirac semimetal film from 40 meV to 80 meV, the absorption bandwidth and absorption peaks can be dynamically tuned. To explain the mechanism of high absorption, the magnetic field, surface current, and power loss density distributions at different resonant frequencies were presented. Our work may have potential applications in various fields such as sensors, detectors, and photovoltaic devices in THz regions.