Isolation, Kinetics, and Performance of a Novel Phenol Degrading Strain

Efficient phenol-degrading bacteria is still the key to the biological treatment of phenol-containing wastewater. In this research, a novel phenol-degrading strain N8 was isolated. According to the 16S rDNA identification, it was concluded that the N8 strain was Bacillus sp. IARI-J-20. The wastewater treatment experiments showed that the phenol degrading rate of N8 reached 92.8 % at 24 h with the inoculation amount of 15 %, temperature of 30 °C, pH of 7.2, yeast extract addition of 0.08 %, and initial phenol concentration of 225 mg L–1. Haldane’s model was fit for the growth kinetics of the phenol-degrading strain N8 over a wide range of initial phenol concentrations (50–1200 mg L–1), with kinetic values μmax = 0.33 h−1, Ks = 79.16 mg L–1, and Ki = 122 mg L–1. The yield coefficient reached maximal value when the phenol concentration was 400 mg L–1. When the initial phenol concentration was more than 400 mg L–1, the inhibition effect of phenol became predominant. This work is licensed under a Creative Commons Attribution 4.0 International License

Skyrmion-skyrmion and skyrmion-edge repulsions in skyrmion-based racetrack memory

Magnetic skyrmions are promising for building next-generation magnetic memories and spintronic devices due to their stability, small size and the extremely low currents needed to move them. In particular, skyrmion-based racetrack memory is attractive for information technology, where skyrmions are used to store information as data bits instead of traditional domain walls. Here we numerically demonstrate the impacts of skyrmion-skyrmion and skyrmion-edge repulsions on the feasibility of skyrmion-based racetrack memory. The reliable and practicable spacing between consecutive skyrmionic bits on the racetrack as well as the ability to adjust it are investigated. Clogging of skyrmionic bits is found at the end of the racetrack, leading to the reduction of skyrmion size. Further, we demonstrate an effective and simple method to avoid the clogging of skyrmionic bits, which ensures the elimination of skyrmionic bits beyond the reading element. Our results give guidance for the design and development of future skyrmion-based racetrack memory.Comment: 15 pages, 6 figure

Optimal Scheduling Strategy for a Grid-connected Photovoltaic System for Heat Pump Water Heaters

AbstractThe aim of this paper is to develop an optimal scheduling strategy model for a grid-connected photovoltaic (PV) system to power heat pump water heaters (HPWH). The system is composed of PV modules which are grid-tied. The PV is capable of supplying power simultaneously to the HPWH and domestic loads whilst the grid is a complimentary source. The cost function of this model is to minimize energy cost, while the PV power outputs to the HPWH and domestic appliances are to be maximized. The time-of-use (TOU) electricity tariff is taken into account in the optimal scheduling model. The control variables are the power flows within the branches of the system. The optimal control strategy of this grid-connected PV system can be implemented to reduce the power demand and serve as means of load shifting while meeting technical and operational constraints. This model is shown to have more economical benefits than the solar thermal heaters, because of the possibility of turning house buildings into energy positive if the feed-in tariffs become attractive. A case study was done based on 3x16kW HPWH installed at Pretoria hotel in South Africa. Simulations run over year on selected seasonal dates using actual fluctuating coefficient of performance (COP) of the HPWH. The optimal results show how solar output variation and TOU affect the scheduling strategy of the HPWH. The energy cost savings are as well presented in this paper

Multivariate adaptive regression splines for estimating riverine constituent concentrations

Regression-based methods are commonly used for riverine constituent concentration/flux estimation, which is essential for guiding water quality protection practices and environmental decision making. This paper developed a multivariate adaptive regression splines model for estimating riverine constituent concentrations (MARS-EC). The process, interpretability and flexibility of the MARS-EC modelling approach, was demonstrated for total nitrogen in the Patuxent River, a major river input to Chesapeake Bay. Model accuracy and uncertainty of the MARS-EC approach was further analysed using nitrate plus nitrite datasets from eight tributary rivers to Chesapeake Bay. Results showed that the MARS-EC approach integrated the advantages of both parametric and nonparametric regression methods, and model accuracy was demonstrated to be superior to the traditionally used ESTIMATOR model. MARS-EC is flexible and allows consideration of auxiliary variables; the variables and interactions can be selected automatically. MARS-EC does not constrain concentration-predictor curves to be constant but rather is able to identify shifts in these curves from mathematical expressions and visual graphics. The MARS-EC approach provides an effective and complementary tool along with existing approaches for estimating riverine constituent concentrations

Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells

We study the hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells. The corresponding polariton states are given. The analytical solution and the numerical result of the stationary spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic

Formation mechanism and control of the spiral marks of three-roll skew-rolled hollow axles

The spiral marks is one of the main surface quality defects of the three-roll skew rolled hollow axles. In order to eliminate the spiral marks, it is necessary to clarify the cause of the spiral marks on the surface of the rolled piece. Based on the analysis of the kinematics of the three-roll skew rolled hollow axles, the spiral marks is caused by the spiral pitch of the rolled piece being larger than the width of the finishing section of the roller. Increasing the rotation speed of the roller can reduce the spiral pitch of the rolled piece, thereby avoiding the appearance of spiral marks. The correctness of the proposed condition for preventing the defect of spiral marks is verified by simulation

Increased human occupation and agricultural development accelerates the population contraction of an estuarine delphinid

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