Review on Chromobacterium Violaceum for Gold Bioleaching from E-waste

AbstractElectronic waste, such as printed circuit boards, are an important secondary resource if processed with environment-friendly technologies for obtaining precious metal, such as gold. The gold bioleaching from electronic waste was recently getting paid attractive attention because its available deposit is limited. This review was focused on Chromobacterium violaceum (C. Violaceum), which was a mesophilic, gram-negative, and facultative anaerobe. C. violaceum has the ability of producing CN− which can dissolve gold from the metallic particles of crushed waste printed circuit boards. This article also provided an overview of cyanide-generation mechanism and the optimal conditions for C. violaceum to achieve maximum amount of cyanide generation. The past achievements and recently scenario of recovery studies carried out on the use of some other microorganisms were compared with C. violaceum. And recently some researchers proposed that combined C. violaceum with chemical methods or other mechanism such as iodide, Pseudomonas aeruginosa and Pseudomonas fluorescens which can reinforce the cyanide generation and improve gold-leaching efficiency. The factors affected the microorganisms on cyanide generation were summarized and the proper conditions were also discussed in this article. And present researches of C. violaceum in gold bioleaching had made good progress which the reported leaching efficiency of gold was over 70%

Thoughts and Targeted Initiatives for the Nurturing of Youth Football Reserve Talents in China

In order to strengthen the foundation for the cultivation of Chinese youth football reserve talents, a systematic review of the current ideas on the development of Chinese youth football reserve talents is conducted, and based on this, a targeted response is derived from it. The study concludes that the cultivation of Chinese youth football reserve talents should be based on the country and the world in a hierarchical and directional manner, with emphasis on the integration of the excellent Chinese traditional culture at the primary school level and the absorption of outstanding foreign achievements and experience at the secondary school level, and the promotion of three types of policy tools, namely the supply side, the demand side and the environment side, to form a protective synergy for the cultivation of youth football reserve talents, so as to build an effective and long-term development strategy that will benefit the present and the future. The aim is to speed up the construction of a reserve pool of Chinese youth football talents, improve the international competitiveness and influence of Chinese football, and contribute to the early realisation of the Chinese football dream

Multidimensional Meaning, Existing Problems and Optimization Path for the Management of Coaches in Chinese University Basketball League

A well-managed level of competition and training by coaches is an essential catalyst for the achievement of talent development goals in the Chinese University Basketball League. This study compares the multi-dimensional meaning of the management of coaches in the Chinese College Basketball League, and analyses the existing management problems based on the SMART principle, the 4P model of human resource management, and the GROW model, to propose feasible measures to optimize the management of coaches. This research aims to provide a theoretical reference and practical basis for the improvement of the management and to provide a driving force for the realization of the long-term goal of talent training in the Chinese University Basketball League

Exploring the Cosmic Reionization Epoch in Frequency Space: An Improved Approach to Remove the Foreground in 21 cm Tomography

Aiming to correctly restore the redshifted 21 cm signals emitted by the neutral hydrogen during the cosmic reionization processes, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency space to investigate whether they works satisfactorily with complex foreground, by quantitatively evaluate the quality of restored 21 cm signals in terms of sample statistics. We construct the foreground model to characterize both spatial and spectral substructures of the real sky, and use it to simulate the observed radio spectra. By comparing between different separation approaches through statistical analysis of restored 21 cm spectra and corresponding power spectra, as well as their constraints on the mean halo bias $b$ and average ionization fraction $x_e$ of the reionization processes, at $z=8$ and the noise level of 60 mK we find that, although the complex foreground can be well approximated with quadratic polynomial expansion, a significant part of Mpc-scale components of the 21 cm signals (75% for $\gtrsim 6h^{-1}$ Mpc scales and 34% for $\gtrsim 1h^{-1}$ Mpc scales) is lost because it tends to be mis-identified as part of the foreground when single-narrow-segment separation approach is applied. The best restoration of the 21 cm signals and the tightest determination of $b$ and $x_e$ can be obtained with the three-narrow-segment fitting technique as proposed in this paper. Similar results can be obtained at other redshifts.Comment: 33 pages, 14 figures. Accepted for publication in Ap

One-step preparation of optically transparent Ni-Fe oxide film electrocatalyst for oxygen evolution reaction

Optically transparent cocatalyst film materials is very desirable for improved photoelectrochemical (PEC) oxygen evolution reaction (OER) over light harvesting photoelectrodes which require the exciting light to irradiate through the cocatalyst side, i.e., front-side illumination. In view of the reaction overpotential at electrode/electrolyte interface, the OER electrocatalysts have been extensively used as cocatalysts for PEC water oxidation on photoanode. In this work, the feasibility of a one-step fabrication of the transparent thin film catalyst for efficient electrochemical OER is investigated. The Ni-Fe bimetal oxide films, 200 nm in thickness, are used for study. Using a reactive magnetron co-sputtering technique, transparent (> 50% in wavelength range 500-2000 nm) Ni-Fe oxide films with high electrocatalytic activities were successfully prepared at room temperature. Upon optimization, the as-prepared bimetal oxide film with atomic ratio of Fe/Ni = 3:7 demonstrates the lowest overpotential for the OER in aqueous KOH solution, as low as 329 mV at current density of 2 mA cm 2, which is 135 and 108 mV lower than that of as-sputtered FeOx and NiOx thin films, respectively. It appears that this fabrication strategy is very promising to deposit optically transparent cocatalyst films on photoabsorbers for efficient PEC water splitting.This work was financially supported by the National Natural Science Foundation of China (No. 21090340), 973 National Basic Research Program of the Ministry of Science and Technology (No. 2014CB239400) and Solar Energy Action Plan of Chinese Academy of Sciences (KGCX2-YW-399+7-3)