Guanidine Catalyzed Enantioselective Mannich Reaction: Towards the Synthesis of ?-Amino Acids

Ph.DDOCTOR OF PHILOSOPH

Optimal Design of a High Temperature Superconducting Homopolar Inductor Machine

A high temperature superconducting homopolar inductor machine (HTS-HIM) is optimally designed considering the effect of magnetic field on HTS coil in this paper. Firstly, the structure and operation principle of HTS-HIM are presented. The three-dimensional HTS-HIM finite element analysis model and two-dimensional axisymmetric direct coupling model of HTS-HIM based on T-A formulation are established. Secondly, the excitation window parameters, the excitation current and number of turns of HTS coil are optimized, taking into account the HTS-HIM performance and the safety of HTS coil. Thirdly, the magnetic field weakening capabilities of the U-shaped flux diverter and copper layer are analyzed and their parameters are optimized. Finally, the optimal design scheme and the critical current of HTS coil in HTS-HIM are obtained

Cell transcriptomic atlas of the non-human primate Macaca fascicularis.

Studying tissue composition and function in non-human primates (NHPs) is crucial to understand the nature of our own species. Here we present a large-scale cell transcriptomic atlas that encompasses over 1 million cells from 45 tissues of the adult NHP Macaca fascicularis. This dataset provides a vast annotated resource to study a species phylogenetically close to humans. To demonstrate the utility of the atlas, we have reconstructed the cell-cell interaction networks that drive Wnt signalling across the body, mapped the distribution of receptors and co-receptors for viruses causing human infectious diseases, and intersected our data with human genetic disease orthologues to establish potential clinical associations. Our M. fascicularis cell atlas constitutes an essential reference for future studies in humans and NHPs.We thank W. Liu and L. Xu from the Huazhen Laboratory Animal Breeding Centre for helping in the collection of monkey tissues, D. Zhu and H. Li from the Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory) for technical help, G. Guo and H. Sun from Zhejiang University for providing HCL and MCA gene expression data matrices, G. Dong and C. Liu from BGI Research, and X. Zhang, P. Li and C. Qi from the Guangzhou Institutes of Biomedicine and Health for experimental advice or providing reagents. This work was supported by the Shenzhen Basic Research Project for Excellent Young Scholars (RCYX20200714114644191), Shenzhen Key Laboratory of Single-Cell Omics (ZDSYS20190902093613831), Shenzhen Bay Laboratory (SZBL2019062801012) and Guangdong Provincial Key Laboratory of Genome Read and Write (2017B030301011). In addition, L.L. was supported by the National Natural Science Foundation of China (31900466), Y. Hou was supported by the Natural Science Foundation of Guangdong Province (2018A030313379) and M.A.E. was supported by a Changbai Mountain Scholar award (419020201252), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16030502), a Chinese Academy of Sciences–Japan Society for the Promotion of Science joint research project (GJHZ2093), the National Natural Science Foundation of China (92068106, U20A2015) and the Guangdong Basic and Applied Basic Research Foundation (2021B1515120075). M.L. was supported by the National Key Research and Development Program of China (2021YFC2600200).S

Design of HTS Excitation Coil for Homopolar Inductor Machine Considering Critical Current Reduction of Local Turn

The high temperature superconducting homopolar inductor machine (HTS-HIM) is identified as a promising candidate for the high-speed field of superconducting machine. The reliability and performance of HTS-HIM is closely related to the critical current of its HTS excitation coil. However, the critical current is limited by the turn with the highest risk of quench, which means that not all the turns of HTS coil can achieve the best performance. Targeting ensures the reliability of HTS-HIM and enhance the utilization rate of HTS tape, the HTS coil is designed considering the critical current reduction of local turn in this paper. Firstly, the operation principle of HTS-HIM is illustrated, and the design process is given. Then, the feasibility of calculating critical current using constant sweep rate method is described, and the HTS coil of a 10 kW HTS-HIM is designed utilizing the MAX criterion. Thirdly, the external field of the HTS coil is analyzed based on the simplified model of HTS-HIM. According to the external field distribution, an easily installed L-shaped flux diverter is proposed to suppress critical current reduction of local turn of HTS coil. The results show that the current safety margin is increased by 24 % at the cost of very little extra loss and weight through the proposed method

Organic dye-photocatalyzed acylnitroso ene reaction

Rose bengal, an inexpensive and readily available organic dye, is demonstrated to be a photoredox catalyst for the formation of transient acylnitroso intermediates under visible light irradiation. This method is operationally simple and uses air as the terminal oxidant. Reactions of acylnitroso with a range of functionalized alkenes give intermolecular acylnitroso ene products in moderate to good yields. This is an environmentally friendly allylic amination methodology that avoids the use of metal catalysts and stoichiometric amount of oxidants. A plausible reaction mechanism is proposed on the basis of singlet oxygen and fluorescence quenching studies

Investigation and Suppression of External Alternating Field of HTS Excitation Coil in Homopolar Inductor Machine

In high temperature superconducting homopolar inductor machine (HTS-HIM), the stationary HTS excitation coil is directly exposed to complex external perpendicular alternating field (EPAF). In this situation, the AC loss including dynamic loss and magnetization loss will occur in the HTS coil carrying direct current, which is harmful to the operation of HTS-HIM. To avoid the thermal runaway quench of HTS coil caused by AC loss and ensure the safe and reliable operation of HTS-HIM, the EPAF acting on the HTS coil is investigated and suppressed in this article. Firstly, the characteristics of the EPAF of HTS coil in HTS-HIM are obtained through theoretical and finite element analysis. Then, based on the distribution of EPAF and the special structure of HTS-HIM, a combined suppression method using two sets of U-shaped armature windings and L-shaped flux diverter is proposed and analyzed. The results show that the shielding factors of fundamental and DC components can be reduced to 25 % and 31 %, respectively

Design of a 10kW Superconducting Homopolar Inductor Machine Based on HTS REBCO Magnet

The electric aircraft propulsion system requires high speed and high power-weight ratio electrical machines. This paper presents a superconducting homopolar inductor machine (HIM) based on HTS REBCO magnets, which could be a promising candidate for high power density electrical machines for future electric aircraft propulsion system. The HTS-HIM has a simple structure, high rotating speed, and huge potential to achieve a high power-weight ratio (kW/kg). This paper presents our design of a 10 kW HTS-HIM with a rotating speed of 3000 rpm. The structure and crucial parameters of HTS-HIM are presented. A 2D-axial pancake coil model for HTS REBCO magnets was built by using COMSOL. Based on this model, HTS REBCO magnets were design and optimized. The loss of REBCO magnets was also calculated. Finally, the output performance of the 10 kW HTS-HIM was simulated. Our work provides preliminary simulation and analysis for future MW-class HTS-HIM

Graphene Oxide-Polythiophene Hybrid with Broad-Band Absorption and Photocatalytic Properties

Hybrid graphene oxide (GO)/poly(3-hexylthiophene-2,5-diyl) (P3HT) sheets are assembled via pi-pi interaction and carefully isolated from the nonreacted precursors. The mutual influence of the two phases can be sharply manifested in this layer-to-layer configuration because it is undiluted by excess of one phase. To investigate the optical properties of the hybrid and possible synergistic interactions, we applied photothermal deflection spectroscopy (PDS) and pump-probe techniques. For the first time, the photocatalytic performance of these hybrids was investigated to correlate with their optical properties. The GO-P3HT hybrid demonstrates broad-band absorption and ultrafast charge transfer (1.4 ps) and acts as an excellent photocatalyst for the Mannich reaction (93% yield).close1