Split ring hole metamaterial-enhanced pyroelectric detector for efficient multi-narrowband terahertz detection.

Derived from infrared pyroelectric detection, typical terahertz (THz) pyroelectric detectors have low sensitivity at low-frequency THz bands. Based on the high-efficiency absorption of the metamaterial perfect absorber (MPA), a novel split ring hole metamaterial-enhanced pyroelectric detector is proposed to achieve efficient multi-narrowband THz detection. Using high frequency simulation software (HFSS), the dimensional parameters including ring radius, ring width, connection beam width, array period, and thickness, are optimized to enhance efficient multi-narrowband absorption. The as-optimized metamaterial-enhanced detectors are fabricated via micro-nano manufacturing technology. The voltage responsiveness and noise equivalent power of the metamaterial-enhanced detector are tested by THz focused optical path and compared with those of the typical pyroelectric detector and the simulated MPA absorptivity. The results indicate that the metamaterial-enhanced detector has a multi-narrowband detection capability at 0.245 THz, 0.295 THz, and 0.38 THz, which is close to the simulated MPA absorptivity. Compared to the typical pyroelectric detector, the split ring hole metamaterial-enhanced detector can simultaneously achieve thermal absorption, thermal conduction, and pyroelectricity in the same MPA structure, providing faster response speed above 100 Hz chopper frequency and two times higher detection sensitivity at multi-narrowband THz frequencies. This research can be used for THz sensing, absorption filtering, biological macromolecule detection, and other applications.

Efficient fluorescence coupling microlens integrated fiber magnetometer probe based on nitrogen vacancy centers.

The nitrogen vacancy (NV) centers in diamonds have gathered increasing interest as an emerging quantum sensing platform with high sensitivity and spatial resolution. Integration of micro-sized diamond and fiber is an essential method to build an NV center endoscope probe and enable NV center sensors for practical application. However, the low fluorescence collection efficiency of fibers due to their small numerical aperture (NA) has limited the sensitivity of the sensors. In this paper, a cone-shape microlens was fabricated using the photopolymerization process at the end of a multimode fiber to boost the laser excitation and fluorescence collection efficiency of NV centers. Experiments demonstrated that over 21 times fluorescence intensity enhancement and 12 times sensitivity improvement were achieved. This fiber-microlens magnetometer probe exhibited a 2.1-nT/Hz1/2 sensitivity over a bandwidth of 100 Hz with ∼80-µm diameter diamond. This research presented a robust and large NA diamond integrated fiber-microlens magnetometer probe, which can also be expanded to magnetic field scan and real-time monitoring.

Theoretical Analysis of a Magnetic Shielding System Combining Active and Passive Modes.

Considering the magnetic shielding requirements of both geomagnetic field and 50 Hz power-line frequency in the complex working conditions of the power grid, an electromagnetic shielding system combining active and passive modes is proposed in this article. A three-dimensional Helmholtz coil with a magnetic shielding barrel nested inside is established by the COMSOL simulation tool, and the magnetic shielding efficiency of the system is analyzed. Comparing different materials, the simulation results indicate that permalloy alloy exhibits better shielding performance than pure iron and nickel materials. Additionally, the overall shielding efficiency of the shielding barrel increases linearly with the number of multiple layers. Under the combined active and passive electromagnetic shielding conditions, the system achieves a shielding efficiency of SE = 113.98 dB, demonstrating excellent performance in shielding both AC and DC interference magnetic fields. This study provides theoretical guidance for the construction of magnetic shielding systems in electromagnetic interference environment.

A Co-Sputtering Process Optimization for the Preparation of FeGaB Alloy Magnetostrictive Thin Films.

A co-sputtering process for the deposition of Fe0.8Ga0.2B alloy magnetostrictive thin films is studied in this paper. The soft magnetic performance of Fe0.8Ga0.2B thin films is modulated by the direct-current (DC) sputtering power of an FeGa target and the radio-frequency (RF) sputtering power of a B target. Characterization results show that the prepared Fe0.8Ga0.2B films are amorphous with uniform thickness and low coercivity. With increasing FeGa DC sputtering power, coercivity raises, resulting from the enhancement of magnetism and grain growth. On the other hand, when the RF sputtering power of the B target increases, the coercivity decreases first and then increases because of the conversion of the films from a crystalline to an amorphous state. The lowest coercivity of 7.51 Oe is finally obtained with the sputtering power of 20 W for the FeGa target and 60 W for the B target. Potentially, this optimization provides a simple way for improving the magnetoelectric coefficient of magnetoelectric composite materials and the sensitivity of magnetoelectric sensors.

A Flexible Pressure Sensor Based on Graphene/Epoxy Resin Composite Film and Screen Printing Process.

At present, flexible pressure-sensitive materials generally have problems with weak adhesion and poor wear resistance, which easily result in friction failure when used for plantar pressure detection. In this study, a flexible pressure sensor with the advantages of a wide detection range, fast recovery, and good abrasive resistance was designed and prepared based on the screen printing process. The pressure-sensitive unit with a structural size of 5 mm× 8 mm was a functional material system due to the use of graphene and epoxy resin. The influence of the different mass ratios of the graphene and epoxy resin on the sensing properties was also studied. The test results showed that when the mass ratio of graphene to epoxy resin was 1:4, the response time and recovery time of the sensing unit were 40.8 ms and 3.7 ms, respectively, and the pressure detection range was 2.5-500 kPa. The sensor can detect dynamic pressure at 0.5 Hz, 1 Hz, 2 Hz, 10 Hz, and 20 Hz and can withstand 11,000 cycles of bending. In addition, adhesion tests showed that the high viscosity of the epoxy helped to improve the interlayer bond between the pressure-sensitive materials and the flexible substrate, which makes it more suitable for plantar pressure detection environments, where friction is common.

Numerical Investigation of GaN HEMT Terahertz Detection Model Considering Multiple Scattering Mechanisms.

GaN high-electron-mobility transistor (HEMT) terahertz (THz) detectors have been widely studied and applied in the past few decades. However, there are few reports about the influence of GaN/AlGaN heterostructure material properties on the detection model at present. In this paper, a response voltage model for a GaN HEMT THz detector that considers the carrier scattering in a GaN/AlGaN heterostructure is proposed. The phonon scattering, dislocation scattering, and interface roughness scattering mechanisms are taken into account in the classic THz response voltage model; furthermore, the influence of various material parameters on the response voltage is studied. In a low-temperature region, acoustic scattering plays an important role, and the response voltage drops with an increase in temperature. In a high temperature range, optical phonon scattering is the main scattering mechanism, and the detector operates in a non-resonant detection mode. With an increase in carrier surface density, the response voltage decreases and then increases due to piezoelectric scattering and optical phonon scattering. For dislocation and interface roughness scattering, the response voltage is inversely proportional to the dislocation density and root mean square roughness (RMS) but is positively related to lateral correlation length. Finally, a comparison between our model and the reported models shows that our proposed model is more accurate.

All Fiber Vector Magnetometer Based on Nitrogen-Vacancy Center.

Magnetometers based on nitrogen-vacancy (NV) centers in diamonds have promising applications in fields of living systems biology, condensed matter physics, and industry. This paper proposes a portable and flexible all-fiber NV center vector magnetometer by using fibers to substitute all conventional spatial optical elements, realizing laser excitation and fluorescence collection of micro-diamond with multi-mode fibers simultaneously and efficiently. An optical model is established to investigate multi-mode fiber interrogation of micro-diamond to estimate the optical performance of NV center system. A new analysis method is proposed to extract the magnitude and direction of the magnetic field, combining the morphology of the micro-diamond, thus realizing µm-scale vector magnetic field detection at the tip of the fiber probe. Experimental testing shows our fabricated magnetometer has a sensitivity of 0.73 nT/Hz1/2, demonstrating its feasibility and performance in comparison with conventional confocal NV center magnetometers. This research presents a robust and compact magnetic endoscopy and remote-magnetic measurement approach, which will substantially promote the practical application of magnetometers based on NV centers.

Design of High-Precision Parallel AWG Demodulation System.

Here, we present a high-precision demodulation method that supports the arrayed waveguide grating (AWG) system, which includes a 1 × 8 AWG as the primary filter with a 0.5 nm channel spacing and a 1 × 4 AWG as the auxiliary filter with a 1 nm channel spacing. The high precision is achieved through an innovative method of decoupling three channels, involving two adjacent channels of the primary filter and one channel of the secondary auxiliary filter. Simulation results show that the AWGs have a good transmission spectrum with crosstalk below -24.8 dB, non-uniformities below 0.8 dB, insertion loss below -3.7 dB, 3 dB bandwidth of 0.25 nm, and 10 dB bandwidth of 0.43 nm. The interrogation precision can reach 8 pm, with a dynamic range of 0.4 nm, corresponding to a single FBG.

Investigation on the Effect of Annealing Temperature on the Side Ohmic Contact Characteristics for Double Channel GaN/AlGaN Epitaxial Layer.

A side ohmic contact mode for the double channel GaN/AlGaN epitaxial layer is proposed in this paper. Rectangle transmission line model (TLM) electrodes are prepared, and the specific contact resistance is tested at the annealing temperatures from 700 °C to 850 °C. The results show that the minimum specific contact resistance is 2.58 × 10-7 Ω·cm2 at the annealing temperature of 750 °C, which is three to four times lower than the surface contact mode. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and atomic force microscope (AFM) were carried out for the analysis of the morphology, element composition, and the height fluctuation at the contact edge. With the increase in the annealing temperature, the specific contact resistance decreases due to the alloying of electrodes and the raised number of N vacancies. However, when the annealing temperature exceeds 800 °C, the state of the stress in the electrode films transforms from compressive stress to tensile stress. Besides, the volume expansion of metal electrode film and the increase in the roughness at the contact edge leads to the degradation of the side ohmic contact characteristics.

A Terahertz Detector Based on Double-Channel GaN/AlGaN High Electronic Mobility Transistor.

A double-channel (DC) GaN/AlGaN high-electron-mobility transistor (HEMT) as a terahertz (THz) detector at 315 GHz frequency is proposed and fabricated in this paper. The structure of the epitaxial layer material in the detector is optimized, and the performance of the GaN HEMT THz detector is improved. The maximum responsivity of 10 kV/W and minimum noise equivalent power (NEP) of 15.5 pW/Hz0.5 are obtained at the radiation frequency of 315 GHz. The results are comparable to and even more promising than the reported single-channel (SC) GaN HEMT detectors. The enhancement of THz response and the reduction of NEP of the DC GaN HEMT detector mainly results from the interaction of 2DEG in the upper and lower channels, which improves the self-mixing effect of the detector. The promising experimental results mean that the proposed DC GaN/AlGaN HEMT THz detector is capable of the practical applications of THz detection.

LINC00511 knockdown prevents cervical cancer cell proliferation and reduces resistance to paclitaxel.

Cervical cancer (CC) is one of the most common female malignancies in the world. Although paclitaxel (PTX) is a critical chemotherapy agent for the treatment of CC, its treatment outcome is limited by the development of drug resistance. The present study aims to define the role of long non-coding RNA (lncRNA) LINC00511 in the progression of CC with the involvement of cell proliferation, apoptosis and resistance to PTX in Hela/PTX cells. CC and adjacent normal tissue samples were collected from 84 patients with CC, and used to determine LINC0051 expression. PTX-resistant Hela/PTX cell line was constructed, in which LINC0051 was overexpressed or silenced to further investigate the effect of LINC00511 on PTX-resistant Hela/PTX cell viability, proliferation, migration, invasion, cell cycle, apoptosis and resistance of CC cells to PTX. The expression of Bcl-2, Bax, cleaved-caspase-3, matrix metalloproteinase (MMP)-2, MMP-9, multidrug resistance protein 1 (MRP1) and P-glycoprotein (P-GP) was also assessed. High-expression of LINC00511 was found in CC with its close association with the tumor stage, tumor size and lymph node metastasis. After silencing LINC00511 expression, the expression of MRP1, P-GP, Bcl-2, MMP-2 and MMP-9 was decreased, while Bax and cleaved-caspase-3 increased with more CC cells arrested at G1 phase. Furthermore, silencing of LINC00511 could suppress cell resistance to PTX, cell viability, cell proliferation, migration and invasion yet promoted cell apoptosis in PTX-resistant Hela/PTX cells. Collectively, our findings demonstrate that silencing of LINC00511 could inhibit CC cell resistance to PTX, cell proliferation, migration and invasion, and promote cell apoptosis in CC. Silencing of LINC00511 provides a novel therapeutic target for CC.

[The application of double pedicle blood supply pectoralis major myocutaneous flap in reconstruction of laryngeal and hypo pharyngeal defect after carcinoma resection].

OBJECTIVE: To explore the application of double pedicle blood supply pectoralis major myocutaneous flap in reconstruction of laryngeal and hypo pharyngeal defect after carcinoma resection. METHOD: All the patients received initial treatment. Pectoralis major myocutaneous flap was Applied in one-stage reconstruction in 22 cases of laryngocarcinoma and hypopharyngeal carcinoma with post-operation defect. During operation, pectoral branches of thoracoacromial vessels and branch of lateral thoracic vessels were reserved and prepared to be double pedicle vessel fascia bundle without muscle at the beginning part, rearched to defect area through subclavian tunnel. After operation, it is necessary to closely observe the subcutaneous swelling, quantity and color of the drain and others of neck surgery area to exclude the occurrence of surgical hematoma. When there is suspicion, do timely exploration. RESULT: Pectoralis major myocutaneous flaps of 22 patients were all survived. Pharyngeal fistula occurred in 2 cases and was cured by change of dressing. Twenty-one cases received radiotherapy after operation without secondary flap necrosis. After follow-up of 6 months to 24 months, one case of roll repairment of circumferential defect in cervical esophagus,found to have anastomotic stenosis 8 months after radiotherapy and then underwent gastrostomy treatment,the other 21 cases showed good recovery of swallowing function. Among 13 cases with laryngeal function reserved, only 1 case wearing tube and the extubation rate was 92.3% without communication barriers, no patient died in the short follow-up period. CONCLUSION: For double pedicle blood supply pectoralis major nyocutaneous flap, blood supply are fully guaranteed and does not require complicated equipment to observe and monitor the flap blood supply after operation, it is important to exclude factors that may lead to muscular flap necrosis to ensure the survival of pectoralis major myocutaneous flap.

Epidemiologic survey on hospitalized neonates in China.

OBJECTIVE: To carry out a nationwide epidemiologic survey on the neonates in urban hospitals with an attempt to understand the disease spectrum and treatment outcomes of hospitalized neonates in China. METHODS: The clinical data of 43,289 hospitalized neonates from 86 hospitals in 47 Chinese cities (22 provinces) between January 1, 2005 and December 31, 2005 were retrospectively analyzed. RESULTS: The male:female ratio was 1.73:1. Premature infants accounted for 26.2% of the hospitalized neonates, which was higher than that reported in 2002 (19.7%). The top three diseases during the neonatal period were jaundice, pneumonia, and hypoxic-ischemic encephalopathy. The incidences of pneumonia, meconium aspiration syndrome, and bilirubin encephalopathy in term infants were higher than those in premature infants, while the incidences of asphyxia, respiratory distress syndrome, and pulmonary hemorrhage in term infants were lower than those in premature infants. The incidences of asphyxia, small for gestational age infant, and wet lung were higher in neonates whose mother had pregnancy induced hypertension. The outcomes of these hospitalized neonates included: recovered, 63.9%; improved, 27.3%; discharged due to the family's own decisions, 7.6%, and died, 1.2%. Nearly half (46.4%) of the neonatal death occurred within 24 hrs after admission. CONCLUSION: The incidence of premature birth shows an increasing trend among hospitalized neonates. Since the neonatal deaths mainly occur within 24 hrs after admission, monitoring during this period should be enhanced.