Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Small ; : e2310352, 2024 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-38368257

RESUMO

Extensive research has focused on developing wide-bandgap metal compound-based passivating contacts as alternatives to conventional doped-silicon-layer-based passivating contacts to mitigate parasitic absorption losses in crystalline silicon (c-Si) solar cells. Herein, thermally-evaporated aluminum halides (AlX)-based electron-selective passivating contacts for c-Si solar cells are investigated. A low contact resistivity of 60.5 and 38.4 mΩ cm2 is obtained on the AlClx /n-type c-Si (n-Si) and AlFx /n-Si heterocontacts, respectively, thanks to the low work function of AlX. Power conversion efficiencies (PCEs) of 19.1% and 19.6% are achieved on proof-of-concept n-Si solar cells featuring a full-area AlClx /Al and AlFx /Al passivating contact, respectively. By further implementing an ultrathin SiO2 passivation interlayer and a pre-annealing treatment, the electron selectivity (especially the surface passivation) of AlX is significantly enhanced. Accordingly, a remarkable PCE of 21% is achieved on n-Si solar cells featuring a full-area SiO2 /AlFx /Al rear contact. AlFx -based electron-selective passivating contacts exhibit good thermal stability up to ≈400 °C and better long-term environmental stability. This work demonstrates the potential of AlFx -based electron-selective passivating contact for solar cells.

2.
Micromachines (Basel) ; 15(1)2024 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-38258243

RESUMO

In this work, a novel mechanical amplification structure for a MEMS vibratory gyroscope is proposed with the aim of improving their sensitivity. The scheme is implemented using a system of micromachined V-shaped springs as a deflection amplifying mechanism. The effectiveness of the mechanism is first demonstrated for a capacitive fully decoupled quad mass gyroscope. A proof of concept vertical-axis mechanically amplified gyroscope with an amplification factor of 365% has been designed, simulated and fabricated, and results from its evaluation are presented in this paper. Experimental results show that the natural frequency of the gyroscope is 11.67 KHz, and the full scale measurement range is up to ±400°/s with a maximum nonlinearity of 54.69 ppm. The bias stability is 44.53°/h. The experiment results show that this quad mass gyroscope's performance is a very potential new way of reaching the navigation grade in the future.

3.
Sensors (Basel) ; 23(24)2023 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-38139583

RESUMO

In this paper, an event-driven wireless sensor node is proposed and demonstrated. The primary design objective is to devise a wireless sensor node with miniaturization, integration, and high-accuracy recognition ability. The proposed wireless sensor node integrates two vibration-threshold-triggered energy harvesters that sense and power a threshold voltage control circuit for power management, a microcontroller unit (MCU) for system control, a one-dimensional convolutional neural network (1D-CNN) environment data analysis and vibration events distribution, and a radio frequency (RF) digital baseband transmitter with IEEE 802.15.4-/.6 protocols. The dimensions of the wireless sensor node are 4 × 2 × 1 cm3. Finally, the proposed wireless sensor node was fabricated and tested. The alarming time for detecting the vibration event is less than 6 s. The measured recognition accuracy of three events (knock, shake, and heat) is over 97.5%. The experimental results showed that the proposed integrated wireless sensor node is very suitable for wireless environmental monitoring systems.

4.
Asia Pac J Clin Oncol ; 19(4): 458-467, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36101936

RESUMO

INTRODUCTION: The pivotal efficacy study assessed efficacy and safety of GSK's AS04-HPV-16/18 vaccine in Chinese women aged 18-25 years up to 6 years. The present extension study, performed 4 years later, offered AS04-HPV-16/18 vaccination to placebo recipients. Vaccine safety and its long-term protective effect were assessed at Year 10. METHODS: All 6051 women who received AS04-HPV-16/18 or the placebo during the initial study (NCT00779766) were invited to phase III/IV, open-label, partially controlled extension Year 10 study (NCT03629886). Placebo recipients were offered three-dose AS04-HPV-16/18 vaccination and followed up over 12 months to assess the safety. Cervical samples from all women were examined. Vaccine efficacy (VE) against incident infections and cytological lesions associated with HPV-16/18 and other oncogenic types was assessed as exploratory objective. RESULTS: Among 3537 women (out of 6051) enrolled in the extension study, 1791 women (mean age 32.7 years; standard deviation 1.8 years) received AS04-HPV-16/18 and reported no serious adverse events, potential immune-mediated diseases, or adverse pregnancy outcomes related to vaccination. Among 6051 women, VE against incident HPV-16, -18, and -16/18 infections up to Year 10 was 82.8% (95% confidence interval: 72.5-89.7), 79.8% (64.5-89.2), and 80.8% (72.4-87.0), respectively. VE against HPV-16/18 ASC-US+, CIN1+, and CIN2+ was 92.7% (82.2-97.7), 94.8% (67.4-99.9), and 90.5% (34.6-99.8), respectively. CONCLUSION: AS04-HPV-16/18 vaccine showed an acceptable safety profile in Chinese women vaccinated at age 26 years or above, and a long-term protection similar to other efficacy trials worldwide.


Assuntos
Infecções por Papillomavirus , Vacinas contra Papillomavirus , Neoplasias do Colo do Útero , Adolescente , Adulto , Feminino , Humanos , Gravidez , Adulto Jovem , População do Leste Asiático , Seguimentos , Papillomavirus Humano 16 , Papillomavirus Humano 18 , Infecções por Papillomavirus/prevenção & controle , Vacinas contra Papillomavirus/efeitos adversos , Vacinas contra Papillomavirus/uso terapêutico , Neoplasias do Colo do Útero/prevenção & controle
5.
Sensors (Basel) ; 22(12)2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35746115

RESUMO

This paper describes a novel rate and rate-integrating mode-switchable axisymmetric gyroscope. A precession angle tracking algorithm is developed to enable the gyro to switch automatically between rate and rate-integrating modes at preset rate points through a digital control system within the gyro. We also propose a vibrating amplitude control method for the rate-integrating mode that directly extracts the angular rate output to ensure switching stability. In rate mode, the bias instability and angle random walk of the gyro reach 0.106°/h and 0.011°/√h, respectively. Additionally, an input range of over ±5000°/s is measured in rate-integrating mode. The scale factor nonlinearity reaches approximately 116 ppm over the full-scale range. The control system implements effective steering control of the gyroscope, with a switching delay of 10 ms from rate mode to rate-integrating mode and 100 ms from rate-integrating to rate mode. The proposed system actualizes a new type of gyroscope with high accuracy and a wide input range, which combines the benefits of rate and rate-integrating modes.

6.
Infect Dis Poverty ; 11(1): 52, 2022 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-35562755

RESUMO

BACKGROUND: Bulinus globosus, the main intermediate snail host of Schistosoma haematobium. The increased contacts between Africa and China could even lead to large-scale dissemination of B. globosus in China. Temperature is the key factor affecting fresh-water snail transmission. This study predicted potential risk of colonization of B. globosus in the mainland of China under climate change. METHODS: We investigated minimum and maximum temperatures for B. globosus eggs, juveniles and adult snails kept under laboratory conditions to find the most suitable range by pinpointing the median effective temperatures (ET50). We also assessed the influence of temperature on spawning and estimated the accumulated temperature (AT). The average air temperatures between 1955 and 2019 in January and July, the coldest and hottest months in China, respectively, were collected from national meteorological monitoring stations and investigated in a geographic information system (GIS) using empirical Bayesian Kriging to evaluate the theoretical possibility for distribution of B. globosus in southern China based on temperature. RESULTS: The effective minimum temperature (ET50min) for eggs, juveniles, adult snails and spawning were 8.5, 7.0, 7.0, 14.9 °C, respectively, with the corresponding maximum values (ET50max) of 36.6, 40.5, 40.2 and 38.1 °C. The AT was calculated at 712.1 ± 64.9 °C·d. In 1955, the potential B. globosus distribution would have had a northern boundary stretching from the coastal areas of Guangdong Province and Guangxi Autonomous Region to southern Yunnan Province. Since then, this line has gradually moved northward. CONCLUSIONS: Annual regeneration of B. globosus can be supported by the current climate conditions in the mainland of China, and a gradual expansion trend from south to north is shown in the study from 2015 to 2019. Thus, there is a potential risk of colonization of B. globosus in the mainland of China under climate change.


Assuntos
Bulinus , Mudança Climática , Animais , Teorema de Bayes , China , Schistosoma haematobium , Caramujos
7.
Adv Mater ; 34(26): e2200344, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35524638

RESUMO

Advanced doped-silicon-layer-based passivating contacts have boosted the power conversion efficiency (PCE) of single-junction crystalline silicon (c-Si) solar cells to over 26%. However, the inevitable parasitic light absorption of the doped silicon layers impedes further PCE improvement. To this end, alternative passivating contacts based on wide-bandgap metal compounds (so-called dopant-free passivating contacts (DFPCs)) have attracted great attention, thanks to their potential merits in terms of parasitic absorption loss, ease-of-deposition, and cost. Intensive research activity has surrounded this topic with significant progress made in recent years. Various electron-selective and hole-selective contacts based on metal compounds have been successfully developed, and a champion PCE of 23.5% has been achieved for a c-Si solar cell with a MoOx -based hole-selective contact. In this work, the fundamentals and development status of DFPCs are reviewed and the challenges and potential solutions for enhancing the carrier selectivity of DFPCs are discussed. Based on comprehensive and in-depth analysis and simulations, the improvement strategies and future prospects for DFPCs design and device implementation are pointed out. By tuning the carrier concentration of the metal compound and the work function of the capping transparent electrode, high PCEs over 26% can be achieved for c-Si solar cells with DFPCs.

8.
Anal Chem ; 93(17): 6881-6888, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33886279

RESUMO

At present, enzyme-mediated signal amplification strategies have been widely applied in photoelectrochemical (PEC) biosensing systems, while the introduction of natural enzymes onto the surface of photoelectrodes inevitably obstructs the electron transfer due to their insulating properties as proteins, leading to severe damage to photocurrent. In this work, the PdPt bimetallic nanozymes with the efficient peroxidase-like activity were used as alternatives to natural enzymes and amplified PEC biosensing signals via their efficient enzymatic reaction and remarkable enhancement in photocurrent. As a result, photoactive CdS nanorods modified with PdPt bimetallic nanozymes showed a boosted PEC performance compared with the pristine CdS nanorods due to the localized surface plasmon resonance effect and Schottky junction. On the basis of the as-prepared CdS/PdPt photoelectrode, a sensitive split-type glucose oxidase-mediated PEC immunoassay for carcinoembryonic antigen (CEA) detection was successfully constructed. Along with the sandwich immunocomplexing, the subsequently produced hydrogen peroxide (H2O2) can oxidize 4-chloro-1-naphthol into insoluble precipitates to inhibit photocurrent and simultaneously trigger the bio-etching of CdS to further restrain photocurrent signals due to the excellent peroxidase-mimicking activity of PdPt nanozymes. Owing to the synergistic signal amplification fulfilled by PdPt nanozymes, an ultrasensitive immunoassay of CEA was realized with a wider linear range from 1 to 5000 pg/mL and a low detection limit of 0.21 pg/mL, opening a new avenue for building ultrasensitive PEC biosensors with nanozymes.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Glucose Oxidase , Peróxido de Hidrogênio , Imunoensaio , Limite de Detecção
9.
Sensors (Basel) ; 20(4)2020 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-32085651

RESUMO

A high-precision acceleration measurement system based on an ultra-sensitive tunnel magneto-resistance (TMR) sensor is presented in this paper. A "force-magnetic-electric" coupling structure that converts an input acceleration into a change in magnetic field around the TMR sensor is designed. In such a structure, a micro-cantilever is integrated with a magnetic field source on its tip. Under an acceleration, the mechanical displacement of the cantilever causes a change in the spatial magnetic field sensed by the TMR sensor. The TMR sensor is constructed with a Wheatstone bridge structure to achieve an enhanced sensitivity. Meanwhile, a low-noise differential circuit is developed for the proposed system to further improve the precision of the measured acceleration. The experimental results show that the micro-system achieves a measurement resolution of 19 µg/√Hz at 1 Hz, a scale factor of 191 mV/g within a range of ± 2 g, and a bias instability of 38 µg (Allan variance). The noise sources of the proposed system are thoroughly investigated, which shows that low-frequency 1/f noise is the dominant noise source. We propose to use a high-frequency modulation technique to suppress the 1/f noise effectively. Measurement results show that the 1/f noise is suppressed about 8.6-fold at 1 Hz and the proposed system resolution can be improved to 2.2 µg/√Hz theoretically with this high-frequency modulation technique.

10.
Sensors (Basel) ; 20(2)2020 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-31963680

RESUMO

This study presents a new real-time calibration algorithm for three-axis magnetometers by combining the recursive least square (RLS) estimation and maximum likelihood (ML) estimation methods. Magnetometers are widely employed to determine the heading information by sensing the magnetic field of earth; however, they are vulnerable to ambient magnetic disturbances. This makes the calibration of a magnetometer inevitable before it is employed. In this paper, first, a complete measurement error model of the magnetometer is studied, and a simplified model is developed. Then, the real-time RLS algorithm is introduced and discussed in detail, and the unbiased optimal ML is utilized to improve the accuracy of the parameter estimation. The proposed algorithm is advantageous in correcting the parameters in real time and simultaneously obtaining unbiased parameter estimation. Finally, the simulation and experimental results demonstrate that both the accuracy and computational speed of the proposed algorithm is better than those of the widely used bath-processing method. Moreover, the proposed calibration method can be adopted for calibrating other three-axis sensors.

11.
Geospat Health ; 14(1)2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31099516

RESUMO

Schistosomiasis remains a serious health problem in Africa. Although a strong, coordinated agenda for research on this disease has been in place for the last 50 years in Zanzibar, data storage, retrieval of survey data and management remain problem areas. We investigated the use of Google Earth (GE) in conjunction with a hand-held, global positioning system as a pilot project for managing schistosomiasis control. In this way, risk areas can be surveyed and followed up by visualizing both the distribution of human infections and that of the intermediate snail host together with environmental information. A platform with three spatial databases was created: i) Distribution of infected humans; ii) Distribution of the intermediate snail host in ponds (infected and not infected specimens); iii) Distribution of the intermediate snail host in streams (infected and non-infected specimens). The GE spatial database increased the efficiency of follow-up case treatment as well as snail control and contributed also to the discovery of previously unknown areas in need of snail control. We conclude that this platform is advantageous not only by being useful for management and visualization of spatial data, but also because it is easy to operate and available free of charge.


Assuntos
Monitoramento Ambiental/instrumentação , Sistemas de Informação Geográfica/instrumentação , Esquistossomose/epidemiologia , Animais , Humanos , Projetos Piloto , Lagoas , Fatores de Risco , Rios , Caramujos/microbiologia , Tanzânia
12.
Sensors (Basel) ; 18(9)2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30205519

RESUMO

In order to solve the problem where existing mode-matching methods in microelectromechanical systems (MEMS) vibrating gyroscopes fail to meet real-time and reliability requirements, this paper presents a novel method to accomplish automatic and real-time mode-matching based on phase-shifted 45° additional force demodulation (45° AFD-RM). The phase-shifted 45° additional force signal has the same frequency as the quadrature force signal, but it is phase-shifted by 45° and applied to the sense mode. In addition, two-way phase-shifted 45° demodulations are used at the sense-mode detection output to obtain a phase metric that is independent of the Coriolis force and can reflect the mode-matching state. Then, this phase metric is used as a control variable to adaptively control the tuning voltage, so as to change the sense-mode frequency through the negative stiffness effect and ultimately achieve real-time mode-matching. Simulation and experimental results show that the proposed 45° AFD-RM method can achieve real-time matching. The mode frequency split is controlled within 0.1 Hz, and the gyroscope scale factor, zero-bias instability, and angle random walk are effectively improved.

13.
Sensors (Basel) ; 15(12): 30991-1004, 2015 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-26690432

RESUMO

In this paper, the actuation behavior of a two-axis electrothermal MEMS (Microelectromechanical Systems) mirror typically used in miniature optical scanning probes and optical switches is investigated. The MEMS mirror consists of four thermal bimorph actuators symmetrically located at the four sides of a central mirror plate. Experiments show that an actuation characteristics difference of as much as 4.0% exists among the four actuators due to process variations, which leads to an average angular scan error of 0.03°. A mathematical model between the actuator input voltage and the mirror-plate position has been developed to predict the actuation behavior of the mirror. It is a four-input, four-output model that takes into account the thermal-mechanical coupling and the differences among the four actuators; the vertical positions of the ends of the four actuators are also monitored. Based on this model, an open-loop control method is established to achieve accurate angular scanning. This model-based open loop control has been experimentally verified and is useful for the accurate control of the mirror. With this control method, the precise actuation of the mirror solely depends on the model prediction and does not need the real-time mirror position monitoring and feedback, greatly simplifying the MEMS control system.

14.
Nan Fang Yi Ke Da Xue Xue Bao ; 35(11): 1606-9, 2015 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-26607084

RESUMO

OBJECTIVE: To test the feasibility of using 1,5-anhydroglucose alcohol (1,5-AG) as a diagnostic indicator of fulminant type 1 diabetes (FT1DM). METHODS: Fifteen patients with newly diagnosed FT1DM and 52 with type 2 diabetes (T2DM) were examined for serum biochemistry, glycosylated hemoglobin (HbAlc), and serum 1, 5-AG level. RESULTS: The patients with FT1DM and T2DM showed significantly different fasting levels of blood glucose (FBG), fructosamine (FMN), creatinine (Cr), urea, HbAlc and serum 1,5-AG (P<0.05). In FT1DM patients, serum 1,5-AG was found to inversely correlate with FBG (r=-0.646, P=0.032) and FMN (r=-0.680, P=0.021), and in T2DM patients, serum 1,5-AG was inversely correlated with FBG (r=-0.407, P=0.001), FMN (r=-0.314, P=0.01) and HbAlc (r=-0.576, P<0.01). Receiver-operating characteristic (ROC) curve analysis showed an area under the curve of serum 1,5-AG of 0.804 with a cutoff value of 67.95, a sensitivity of 82.9% and a specificity of 60% for FT1DM diagnosis. CONCLUSION: Serum 1, 5-AG can reflect acute blood glucose fluctuation in FT1DM patients and is useful for differential diagnosis of FT1DM when combined with evaluations of the clinical characteristics of the patients and other related indicators.


Assuntos
Glicemia , Diabetes Mellitus Tipo 1/sangue , Etanol , Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Diagnóstico Diferencial , Hemoglobinas Glicadas/química , Humanos , Curva ROC , Sensibilidade e Especificidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...