ABSTRACT
In this study, we propose a method for optimizing the design of CMUT sensors using genetic algorithms. Existing CMUT sensors face frequency response and sensitivity limitations, necessitating optimization to enhance their sensing performance. Traditional optimization methods are often intricate and time-consuming and may fail to yield the optimal solution. Genetic algorithms, which simulate the biological evolution process, offer advantages in global optimization and efficiency, making them widely utilized in the optimization design of Microelectromechanical Systems (MEMS) devices. Based on the theoretical framework and finite element model of CMUT sensors, we propose a CMUT array element optimization design method based on genetic algorithms. The optimization and validation results demonstrate that we have successfully designed a broadband CMUT array element consisting of four microelements with a 1-2 MHz frequency range. Compared with a randomly arranged array element, the optimized array shows a 63.9% increase in bandwidth and a 7.5% increase in average sensitivity within the passband. Moreover, the sensitivity variance within the passband is reduced by 50.2%. Our proposed method effectively optimizes the design of high sensitivity CMUT sensors with the desired bandwidth, thereby offering significant reference value for the optimization design of CMUT sensors.
ABSTRACT
A novel and efficient method to synthesize rigid bis-coumarins based on the dimerization of coumarinyl aldehydes was developed. This procedure is additive- and column-free, providing a facile and environment-friendly way to prepare fluorophores. The prepared novel fluorescent bis-coumarins exhibit favorable photophysical properties with good sensitivity and selectivity towards G-quadruplexes (G4s).
ABSTRACT
The objective of this investigation was to improve the stability of CLA and to allow for its controlled release by encapsulating it with combinations of octenyl-succinic anhydride (OSA) starch and xanthan gum (XG) in three ratios (OSA/XG: 60/1, 80/1, and 100/1, w/w). The wall material was examined using FTIR and TGA. The microcapsules were characterized by laser particle size analysis (LPS) and SEM. Oxidation of the microcapsules was monitored by headspace method. The results revealed that microcapsules created with an OSA/XG ratio of 60/1 provided superior protection to CLA against oxidation. When CLA-microcapsules were subjected to conditions simulating those in the human gastrointestinal system, 12.1%-50.1% of the CLA was released. CLA encapsulation in spray-dried microcapsules of OSA/XG appears to be an effective technique that provides good protection against oxidation and could be useful in the targeted delivery of functional lipids or other bioactive components to the small intestine.
ABSTRACT
Vanadium modified MCM-41 nanospheres were synthesized by the impregnation and sol-gel super-molecular method respectively. Structure and morphology of the obtained materials were characterized using X-ray diffraction (XRD), inductively coupling plasma (ICP), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and N2-adsorption-desorption techniques. The influence of particle sizes on their catalytic activities in styrene oxidation and benzene hydroxylation was investigated. Results revealed that all the samples had regular sphere shape and adjustable particle size within 40-160 nm, and exhibited high catalytic activities in the oxidation of styrene and hydroxylation of benzene. The smaller the particle size is, the higher the activity becomes. Meanwhile, the catalysts synthesized by the sol-gel method are more effective than that synthesized via impregnation method, indicating the vanadium species in the mesoporous framework are probably the catalytic active sites.
