ALBERT

Description: FGF1 and FGF2 are tissue repair drugs, but their activity may be reduced at ambient temperatures and during storage. We demonstrate that FGF1 and FGF2 interact with highly sulfated polysaccharides (heparin, dextran sulfate, and λ‐carrageenan), which increases their thermal stability, and for FGF1, this prolongs its biological activity. Thus, sulfated polysaccharides may be useful excipients for FGF therapeutics. Fibroblast growth factors (FGFs) regulate embryonic development and homeostasis, including tissue and organ repair and specific aspects of metabolism. The basic FGF and acidic FGF, now known as FGF2 and FGF1, are widely used protein drugs for tissue repair. However, they are susceptible to denaturation at ambient temperatures and during long‐time storage, which will reduce their biological activity. The interaction of FGFs with the sulfated domains of heparan sulfate and heparin is essential for their cellular signaling and stability. Therefore, we analyzed the interactions of FGF1 and FGF2 with four sulfated polysaccharides: heparin, dextran sulfate (DXS), λ‐carrageenan, and chondroitin sulfate. The results of thermal stability and cell proliferation assays demonstrate that heparin, DXS, and λ‐carrageenan bound to both FGFs and protected them from denaturation. Our results suggest heparin, DXS, and λ‐carrageenan are potential formulation materials that bind and stabilize FGFs, and which may also potentiate their activity and control their delivery.

Description: A piezoelectric actuator using a lever mechanism is designed, fabricated, and tested with the aim of accomplishing long-travel precision linear driving based on the stick-slip principle. The proposed actuator mainly consists of a stator, an adjustment mechanism, a preload mechanism, a base, and a linear guide. The stator design, comprising a piezoelectric stack and a lever mechanism with a long hinge used to increase the displacement of the driving foot, is described. A simplified model of the stator is created. Its design parameters are determined by an analytical model and confirmed using the finite element method. In a series of experiments, a laser displacement sensor is employed to measure the displacement responses of the actuator under the application of different driving signals. The experiment results demonstrate that the velocity of the actuator rises from 0.05 mm/s to 1.8 mm/s with the frequency increasing from 30 Hz to 150 Hz and the voltage increasing from 30 V to 150 V. It is shown that the minimum step distance of the actuator is 0.875 μm. The proposed actuator features large stroke, a simple structure, fast response, and high resolution.

Description: Irrigation water use efficiency is a primary evaluation index that links economic production development with the efficient use of water resources. Canal water conveyance is an important part of irrigation, and the distribution characteristics of canal systems have an important influence on irrigation water use efficiency. In this paper, 75 irrigated districts in Heilongjiang Province in 2015 were selected as the study objects. The main, branch, lateral, and sublateral canals were graded into first-, second-, third-, and fourth-order classes, respectively. The irrigation districts were divided into three classes, that is, four-order, three-order, and two-order, according to the canal orders that the irrigation districts contained. The canal system framework was described by Horton’s law. The fractal dimension of the canal system was calculated based on the bifurcation ratio and length ratio of the canals. The relationships between fractal dimensions and irrigation water use efficiency were evaluated. The results showed that the irrigation water use efficiency of the four-order and three-order irrigation districts initially increased and then decreased with increases in the fractal dimension (D). In the irrigation districts, an irrigation water use efficiency of more than 10 × 103 hm2 and less than 0.67 × 103 hm2 was proportional to the increase in the fractal dimension, whereas the opposite result was found for districts with (0.67–10) × 103 hm2. The irrigation water use efficiency of the four-order and two-order irrigation districts with less than 3.3 × 103 hm2 had the greatest potential to increase the water use efficiency. Therefore, canal system reconstruction suggestions for different irrigation districts were provided. The results have important theoretical significance and practical value for the improvement of irrigation construction and the promotion of irrigation water efficiency planning.

Description: Piezoelectric actuators are widely used in the optical field due to their high precision, compact structure, flexible design, and fast response. This paper presents a novel piezoelectric actuator with a bridge-type mechanism, which can be used to stabilize the images of an infrared imaging system. The bridge amplification mechanism is used to amplify the actuation displacement, and its structural parameters are optimized by the response surface method. The control strategy of the image stabilization system is formulated, and the overall structure of the infrared image stabilization system is designed according to the principle of image stabilization and the control strategy. The prototype was fabricated and verified by a series of experiments. In the test, the laminated piezoelectric ceramics are used as the driving element, and its maximum output displacement was about 17 μm under a voltage of 100 V. Firstly, the performance of the piezoelectric amplification mechanism was tested, and the maximum displacement of the piezoelectric micro-motion mechanism was 115 μm. The displacement amplification ratio of the mechanism was 5.7. Then, the step distance and response time of the micro-displacement mechanism were measured by inputting the stepping signal. When the input voltage increased to 3 V, 5 V, and 7 V, the stepping displacements of the mechanism were 2.4 μm, 4.1 μm, and 5.8 μm. Finally, the image stabilization effect of the designed mechanism was verified by imaging timing control and feedback signal processing.

Description: The capability of trapping and collecting airborne particulate matter is of great applications in the fields of environmental engineering, healthcare systems, energy engineering, and so forth. In this work, we show a facile strategy of trapping and collecting airborne particulate matter by a simple and compact ultrasonic device system. In this device, a radiation plate is bonded with a Langevin transducer for generating circular standing flexural waves (CSFWs) in the plate. Under the excitation of the CSFWs in the radiation plate, an acoustic field and an acoustic streaming field can be induced in the air gap formed by the radiation plate and a sampling plate. Through numerical simulations, we find that the multiple acoustic streaming vortices symmetric about the central axis in the air gap are responsible for trapping and collecting airborne particulate matter onto the sampling plate, while acoustic radiation force contributes little. Also, it is numerically found and experimentally verified that the resonant acoustic field and the accompanying acoustic streaming field can be tuned by varying the thickness of air gap. Through experimentation, we investigate and clarify the dependency of collection performance on parameters such as the air gap thickness and radius, sonication time, driving voltage, and the angle between the radiation plate and the sampling plate. Due to its contactless and mild handling attributes, our ultrasonic airborne particulate matter sampler can circumvent the clogging and secondary pollution issues and ensure device reusability and little damage to samples compared with other airborne particulate matter processing methods.