In this work, enhancement of daptomycin production by genome shuffling in Streptomyces roseosporus was conducted. Ultraviolet and NTG were used as mutagenizing agents to improve the volumetric productivity of the wild-type strain. Eight strains with enhanced daptomycin production were screened out as the starting population for genome shuffling. Daptomycin's production increased steadily with each round of genome shuffling. After the fourth round of fusion, a high-production strain (582 mg/L), named F4, was selected as a potential industrial production strain and its heredity stability was stable. Moreover, comparative analysis of the non-ribosomal peptide synthetase (NRPS) genes at the transcript level between the wild and the mutant was studied by RT-PCR in order to explore mechanism of genome shuffling. The transcript levels of NRPS genes dptA, dptBC, and dptD in the mutant were approximately 6.5 to 7 times higher than those in the wild. In summary, it is suggested that this strategy for increasing the daptomycin production in S. roseosporus by genome shuffling may provide an alternative approach to enhance the metabolite production in other Streptomyces.
GPS has been offering commercial outdoor positioning services. However, it is not suitable for indoor positioning purposes because of the weak satellite signals indoors. Therefore, the ultrasound technology has been developed and applied to indoor positioning for automated guided vehicles (AGVs) or moving robots. Unfortunately, traditional trilateral ultrasound methods usually suffer from a narrow coverage range and low accuracy. For this reason, we firstly systematically analyze the effects of ultrasound wave loss on positioning and those of the ultrasonic signal receiving angle. On the basis of fundamental information, a multi-degrees-offreedom (Multi-DoF) ultrasonic positioning system is then proposed. The Multi-DoF system is constructed using two steering engines, where one has a 360-degree horizontal rotating angle and the other one has a vertical rotating angle greater than 180 degrees. Accordingly, it can efficiently receive all signals from the ultrasonic transmitting device of a moving AGV. Experimental results confirm that the proposed method can reduce the average positioning error to 3.2 cm, significantly improving the accuracy compared with existing trilateral methods.
Based on the theory of ultrasonic vibration, a new type of ultrasonic atomizing vibrator (UAV) with a vibrating steel sheet was proposed. By using the finite element analysis software to simulation analysis and research for the new type of vibrator, the frequency and vibration mode of atomizing steel sheet was obtained and the prototype of vibrator was fabricated. The impedance and vibration displacement of the vibrator was tested and the experiment of the new type of vibrator was carried out, which verified the feasibility of the new type of vibrator design method.
Abstract. A design method of ultrasonic vibration petrol atomizer vibrator was proposed based on one-dimensional elastic vibration theory. The model and harmonic analyses of the vibrator were performed by using the FEA software ANSYS. Experimental Study of the petrol atomizer was carried out and the atomization performance of the prototype was verified.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.