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Combining microbial and chemical syntheses for the production of complex naturalproducts

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Chinese Journal of Natural Medicines 2022年第10期20卷 729-736页

作者： ZHANG Haili TANG Xiaoyu institute of Chemical Biology Shenzhen Bay LaboratoryShenzhen 518132China

Nature,a rich source of bioactive natural products,serves as a massive pool of drug candidates for the pharmaceutical ***,the supply of these structurally complex chemicals is costly as most of the natural products are scarce in nature,thus requiring de novo *** supply chain issue hinders the development of novel therapeutic agents from natural *** synthesis,based on the expression of biosynthetic genes in a suitable microbial host to produce certain chemicals,is a sustainable strategy to produce complex natural ***,this strategy requires gaining insights into the biosynthesis of target *** natural products are biosynthetically unknown or not fully elucidated;thus,the sole application of microbial synthesis strategy to produce a given molecule is *** this review,we highlight a strategy that combines microbial and chemical syntheses to tackle the supply chain issue in developing drugs from natural *** believe this strategy can revive the drug development pipeline for natural products.

关键词： Microbial Chemical syntheses Biosynthesis Brasilicardins

Driving Torque Reduction in Linkage Mechanisms Using Joint Compliance for Robot Head

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 888-895页

作者： ZHONG Chunhao YANG Xiaojun shenzhen Graduate School Harbin Institute of Technology

The conventional linkage mechanisms with compliant joint have been widely studied and implemented for increasing the adaptability of the mechanism to external contacts. However, the analysis of how compliant joints in linkage mechanism can reduce the energy consumption isn＇t still studied deeply. In a mobile service robot head, the actions of blinking the eyes and moving the eyeballs are realized by the planar linkage mechanism respectively. Therefore, minimizing the driving torques through motion trajectories for the linkage mechanism, which will be beneficial to extend the working time for mobile service robots. The dynamic modeling of the linkage mechanism with springs-loaded compliant joint is established. An optimization procedure for obtaining the optimal parameters of springs is proposed for minimizing the max value of driving torques within a range of desired operating conditions. The Simulations prove that the linkage mechanism with compliant joints can effectively reduce the driving torques, and reduce the energy consumption consequently. The framework can also be applied in other similar applications to reduce the driving torque and save energy. Compared with previous efforts, this is the first attempt that the linkage mechanism with complaint joint is applied in the robot head for reducing the driving torque.

关键词： robot head compliant joint linkage mechanism driving torque reduction save energy

Sequencing and analysis of the giant panda genome

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Science China(Life Sciences) 2010年第8期53卷 1047-1048页

作者： YANG HuanMing BGI-shenzhen (Beijing Genomics institute shenzhen), shenzhen 518083, China BGI-shenzhen (Beijing Genomics institute shenzhen) Shenzhen China

The giant panda (Ailuropoda melanoleuca) is loved all over the world and is considered a symbol of China, as illustrated by its being one of the

关键词： Sequencing and analysis of the giant panda genome

Transient thermal cracking associated with non-classical heat conduction in cylindrical coordinate system

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Acta Mechanica Sinica 2013年第2期29卷 211-218页

作者： Bao-Lin Wang Graduate School at shenzhen Harbin Institute of Technology

This paper studies the fracture behavior of a thermoelastic cylinder subjected to a sudden temperature change on its outer surface within the framework of non-classical heat *** heat conduction equation is solved by separation of variable *** form solution for the temperature field and the associated thermal stress are *** critical parameter governing the level of the transient thermal stress is *** expression for the transient stress intensity factor is obtained for a crack in the *** difference between the non-classical solutions and the classical solution are *** is found that the traditional classical heat conduction considerably underestimates the transient thermal stress and thermal stress intensity factor.

关键词： Thermal stresses·Fracture mechanics·Nonclassical heat conduction

Photocatalytic decomposition of acrylonitrile with N–F codoped TiO_2/SiO_2 under simulant solar light irradiation

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Journal of Environmental Sciences 2015年第7期27卷 169-178页

作者： Dandan Pang Lu Qiu Yunteng Wang Rongshu Zhu Feng Ouyang shenzhen Graduate School Harbin Institute of Technology

The solid acid catalyst, N-F codoped Ti O2/Si O2 composite oxide was prepared by a sol-gel method using NH4 F as nitrogen and fluorine source. The prepared materials were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, X-ray photoelectron spectroscopy（XPS）, UV-Visible diffuse reflectance spectroscopy（UV-Vis）,ammonia adsorption and temperature-programmed desorption（NH3-TPD）, in situ Fourier transform infrared spectroscopy（FT-IR） and N2 physical adsorption isotherm. The photocatalytic activity of the catalyst for acrylonitrile degradation was investigated under simulant solar irradiation. The results showed that strong Lewis and Brnsted acid sites appear on the surface of the sample after N-F doping. Systematic investigation showed that the highest photocatalytic activity for acrylonitrile degradation was obtained for samples calcined at 450°C with molar ratio（NH4F to Ti） of 0.8. The degradation ratio of 71.5% was achieved with the prepared catalyst after 6-min irradiation, demonstrating the effectiveness of photocatalytic degradation of acrylonitrile with N-F codoped Ti O2/Si O2 composite oxide. The photocatalyst is promising for application under solar light ***, the intermediates generated after irradiation were verified by gas chromatography-mass spectrometry（GC-MS） analysis and UV-Vis spectroscopy to be simple organic acids with lower toxicity, and the degradation pathway was also proposed for acrylonitrile degradation with the prepared catalyst.

关键词： Photocatalytic activity Acrylonitrile In situ IR N-F codoping

Improved RIP-based bounds for guaranteed performance of two compressed sensing algorithms

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Science China Mathematics 2023年第5期66卷 1123-1140页

作者： Yunbin Zhao Zhiquan Luo shenzhen Research institute of Big Data The Chinese University of Hong KongShenzhenShenzhen 518172China

Iterative hard thresholding(IHT)and compressive sampling matching pursuit(CoSaMP)are two mainstream compressed sensing algorithms using the hard thresholding *** guaranteed performance of the two algorithms for signal recovery was mainly analyzed in terms of the restricted isometry property(RIP)of sensing *** present,the best known bound using the RIP of order 3k for guaranteed performance of IHT(with the unit stepsize)isδ3k<1/√3≈0.5774,and the bound for CoSaMP using the RIP of order 4k isδ4k<0.4782.A fundamental question in this area is whether such theoretical results can be further *** purpose of this paper is to affirmatively answer this question and to rigorously show that the abovementioned RIP bound for guaranteed performance of IHT can be significantly improved toδ3k<(√5−1)/2≈0.618,and the bound for CoSaMP can be improved toδ4k<0.5102.

关键词： iterative hard thresholding compressive sampling matching pursuit compressed sensing guaranteed performance restricted isometry property

Removal of gaseous volatile organic compounds via vacuum ultraviolet photodegradation: Review and prospect

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Journal of Environmental Sciences 2023年第3期125卷 427-442页

作者： Xue Sun Chaolin Li Boping Yu Jingwen Wang Wenhui Wang School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhen 518055China shenzhen Academy of Environmental Sciences Shenzhen 518001China

Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozoneassisted catalytic oxidation(OZCO) and photocatalytic oxidation(PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary,we propose the challenges of VUV photodegradation and perspectives for its future development.

关键词： Vacuum ultraviolet(VUV) photodegradation Gaseous volatile organic compounds(VOCs) O_(3)elimination

Properties study of LiNbO_3 lateral field excited device working on thickness extension mode

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Chinese Physics B 2010年第9期19卷 584-589页

作者：张志甜张超王文炎马廷锋刘岩冯冠平 Department of Precision Instruments and Mechanology Tsinghua University Research institute of Tsinghua University in shenzhen Shenzhen

This paper investigates the properties of thickness extension mode excited by lateral electric field on LiNbO3 by using the extended Christoffel-Bechmann method. It finds that the lateral field excitation coupling factor for amode （quasi-extensional mode） reaches its maximum value of 28% on Xmcut LiNbO3. The characteristics of a lateral field excitation device made of X-cut LiNbO3 have been investigated and the lateral field excitation device is used for the design of a high frequency ultrasonic transducer. The time and frequency domain pulse/echo response of the LiNbO3 lateral field excitation ultrasonic transducer is analysed with the modified Krimholtz-Leedom-Matthae model and tested using traditional pulse/echo method. A LiNbO3 lateral field excitation ultrasonic transducer with the centre frequency of 33.44 MHz and the -6 dB bandwidth of 33.8% is acquired, which is in good agreement with the results of the Krimholtz-Leedom-Matthae model. Further analysis suggests that the LiNbO3 lateral field excitation device has great potential in the design of broadband high frequency ultrasonic transducers.

关键词： lateral field excitation high frequency ultrasonic transducer LiNb03 thickness extension mode

Engineering nanoporous and solid core-shell architectures of lowplatinum alloy catalysts for high power density PEM fuel cells

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Nano Research 2022年第7期15卷 6148-6155页

作者： Yongqiang Kang Jiaqi Wang Yinping Wei Yongle Wu Dongsheng Xia Lin Gan institute of Materials Research Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Low-platinum(Pt)alloy catalysts hold promising application in oxygen reduction reaction(ORR)electrocatalysis of protonexchange-membrane fuel cells(PEMFCs).Although significant progress has been made to boost the kinetic ORR mass activity at low current densities in liquid half-cells,little attention was paid to the performance of Pt-based catalysts in realistic PEMFCs particularly at high current densities for high power density,which remains poorly *** this paper,we show that,regardless of the kinetic mass activity at the low current density region,the high current density performance of the low-Pt alloy catalysts is dominantly controlled by the total Pt surface area,particularly in low-Pt-loading H_(2)–air *** this end,we propose two different strategies to boost the specific Pt surface area,the post-15-nm dealloyed nanoporous architecture and the sub-5-nm solid core–shell nanoparticles(NPs)through fluidic-bed synthesis,both of which bring in comparably high mass activity and high Pt surface area for large-current-density *** medium current density,the dealloyed porous NPs provide substantially higher H_(2)–air PEMFC performance compared to solid core–shell catalysts,despite their similar mass activity in liquid *** transmission electron microscopy images combined with electron energy loss spectroscopic imaging evidence a previously unreported“semi-immersed nanoporous-Pt/ionomer”structure in contrast to a“fully-immersed core–shellPt/ionomer”structure,thus favoring O_(2) transport and improving the fuel cell *** results provide new insights into the role of Pt nanostructures in concurrently optimizing the mass activity,Pt surface area and Pt/Nafion interface for high power density fuel cells.

关键词： low-platinum alloy catalyst nanoporosity proton-exchange-membrane fuel cells power density triple-phase boundary