Switching Control of Latex Balloon Expansion by using Switching Valve mediated with the Coanda Effect

Soft robots have advantages in terms of safety, softness, and compliance compared to traditional robotic systems. However, fluid-driven soft actuators, often employed in soft robots, require a corresponding number of bulky pressure supplies/valves to drive. Here, we consider a valve that can control the flow without mechanical moving parts for simplifying the driving system of soft actuators. We developed a system comprising a pump, a switching valve, and two latex balloons to demonstrate the feasibility of introducing a fluid valve into soft robotics. As the valve, which makes use of the Coanda effect, can switch the flow between two outlets when the pressure difference between the outlets is 3 kPa, we employed a latex balloon connected to each outlet. The system can control the expansion of each balloon by switching the flow from the pump. The experimental results proved that the system could actuate each balloon.

Determination of Lead Employing Simple Flow Injection AAS with Monolithic Alginate-Polyurethane Composite Packed In-Valve Column

A simple flow injection FlameAAS for lead determination with an alginate-polyurethane composite (ALG-PUC) monolithic in-valve column has been developed. The ALG-PUC monolithic rod was prepared by mixing methylene diphenyl diisocyanate with polyol and sodium alginate with the ratio of 2:1:1 by weight for a 5 min polymerization reaction. It was then put into a column (0.8 cm i.d × 11 cm length) situated in a switching valve for the FI set up. A single standard calibration could be obtained by plotting the loaded µg Pb2+ vs. FI response (absorbances). The loaded µg Pb2+ is calculated: μg Pb2+ = FRload × LT × CPb2+, where the FR load is the flow rate of the loading analyte solution (mL min−1), LT is the loading time (min), and CPb2+ is the Pb2+ concentration (µg mL−1). A linear calibration equation was obtained: FI response (absorbances) = 0.0018 [µg Pb2+] + 0.0032, R2 = 0.9927 for 1–150 µg Pb2+, and RSD of less than 20% was also obtained. Application of the developed procedure has been demonstrated in real samples.

Design and performance analysis of hydraulic switching valve driven by magnetic shape memory alloy

In this paper, the hydraulic switching valve is designed and its dynamic performance is investigated through proposing a fast response actuator with magnetic shape memory alloy (MSMA) to drive the valve. MSMA actuator with spring return is designed and a double-layered coil is constructed to achieve compactness of electromagnetic case. The dynamic characteristics of the MSMA actuator are analyzed and the step response characteristics is tested. Hydraulic switching valve with MSMA actuator is designed with poppet type. Pressure and velocity field in the flow channel under different valve opening and different inlet and outlet pressure differences are analyzed in COMSOL Multiphysics software. The dynamics of the valve poppet during opening and closing process is modeled mathematically, and simulation analysis are conducted in AMESim software to analyze the response of valve under step and square wave signals. The step response of output flow rate and pressure-flow characteristic under different operating conditions are obtained through experiment. The results show that the MSMA based valve can achieve fast response with opening time of 5 ms at the pressure difference of 1 MPa, providing a theoretical support for the development of hydraulic switching valve with high performance actuator driven by MSMA.

Digital Hydraulic Technology for Linear Actuation: A State of the Art Review

This paper analyses the current state of the art in linear actuation with digital hydraulics. Based on the differences in their aims the paper partitions the area into four actuation concepts – parallel valve solutions, single switching valve solutions, multi-chamber cylinders, and multi-pressure cylinders. The concepts are evaluated based on accuracy and smoothness of motion, switching load, reliability, efficiency and the number of components required.

Characterization of a New Impurity in Metaraminol Bitartrate for Injection by 2D HPLC-Q/TOF-MS, Chemical Synthesis and NMR

Background:: Impurities in pharmaceutical compounds can influence their clinical effects and represent a potential health risk. To ensure the safety and effectiveness of a drug, it is necessary to investigate any potential impurities. Methods:: In this paper, a new impurity was separated and characterized by two-dimensional high performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (2D HPLC-Q/TOF-MS) in negative electrospray ionization mode. The peak containing the new impurity, eluted from the first dimension chromatographic system, was selectively trapped by a switching valve based on its retention time and transferred to the second dimension chromatographic system, which was connected to the mass spectrometer. We obtained MET-TA by chemical synthesis, and its structure was characterized by MS/MS and further confirmed by nuclear magnetic resonance (NMR). Results:: The impurity was found to be (2S, 3S)-2,3.-dihydroxy-4-((1R,2S)-1-hydroxy-1-(3-hydroxyphenyl)propan-2- yl)amino)-4-oxobutanoic acid, labelled as MET-TA. In this study we investigated the mechanism of formation of METTA, and found that it was the amidation product of metaraminol and tartaric acid. Conclusions:: The identification, structural elucidation, synthesis and most probable mechanism of formation of MET-TA are discussed in detail in this paper.

Characteristic investigation of a magnetostrictive fast switching valve for digital hydraulic converter

In order to adapt the frequency requirements of fast switching valve applied to the digital hydraulic converter, a 2/2 way fast switching valve driven by giant magnetostrictive material was performed in this article. The finite element simulation of the fast switching valve’s electromagnetic field and flow field was carried out. In addition, the integrated analytical model of giant magnetostrictive material–fast switching valve coupling with enhanced transmission line method was built in MATLAB/Simulink. The displacement and pressure-flowrate characteristics of giant magnetostrictive material–fast switching valve were discussed and validated in the experiments. The results indicated that the nonlinearity magnetization presents a positive relationship with the driving current before it reaches the saturated state, and the hydraulic force at the expected opening is far less than output force caused by magnetostrictive strain. The experimental valve displacements are in good agreement with obtained results from analytical model, which reveals that the analytical model is accurate enough to predict the main performances of the fast switching valve. The maximum valve displacement without supply pressure is up to 68 µm, which attenuates moderately with the growth of supply pressure. The experimental responses of the displacement and the pressure of giant magnetostrictive material–fast switching valve are less than 1 ms. The amplitude of output flowrate is 8.1 L/min at the frequency of 100 Hz when the pressure drop across giant magnetostrictive material–fast switching valve is 6 MPa theoretically. Similarly, the maximum transient flowrate derived from experiments reaches 8.2 L/min at pressure drop across giant magnetostrictive material–fast switching valve of 5.9 MPa, which is basically consistent with that predicted by analytical model. These reveal that the giant magnetostrictive material–fast switching valve can be utilized in the digital hydraulic converter to improve the system’s efficiency.

Development of a Simple Reversible-Flow Method for Preparation of Micron-Size Chitosan-Cu(II) Catalyst Particles and Their Testing of Activity

A simple flow system employing a reversible-flow syringe pump was employed to synthesize uniform micron-size particles of chitosan-Cu(II) (CS-Cu(II)) catalyst. A solution of chitosan and Cu(II) salt was drawn into a holding coil via a 3-way switching valve and then slowly pumped to drip into an alkaline solution to form of hydrogel droplets. The droplets were washed and dried to obtain the catalyst particles. Manual addition into the alkaline solution or employment of flow system with a vibrating rod, through which the end of the flow line is inserted, was investigated for comparison. A sampling method was selected to obtain representative samples of the population of the synthesized particles for size measurement using optical microscopy. The mean sizes of the particles were 880 ± 70 µm, 780 ± 20 µm, and 180 ± 30 µm for the manual and flow methods, without and with the vibrating rod, respectively. Performance of the flow methods, in terms of rate of droplet production and particle size distribution, are discussed. Samples of 180 µm size CS-Cu(II) particles were tested for catalytic reduction of 0.5 mM p-nitrophenol to p-aminophenol by 100-fold excess borohydride. The conversion was 98% after 20 min, whereas without the catalyst there was only 14% conversion.