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31.
32.
Jinmei Li Wei Wang Fengxia Wang Yumao Kang Ting Tan Ziqiang Lei 《International Journal of Hydrogen Energy》2018,43(2):551-561
The development of biomass-derived nitrogen-doped porous carbons (NPCs) for the oxygen reduction reaction (ORR) is important for sustainable energy systems. Herein, NPCs derived from Astragali Radix (AR) via a cost-effective strategy are reported for the first time. The as-prepared AR-950-5 catalyst shows a stacked layer-like structure and porosity. Notably, the optimized AR-950-5 delivers catalytic activity comparable to that of commercial Pt/C (C-Pt/C), with high onset potential, positive half-wave potential and large limiting current density. It also displays superior long-term stability and methanol tolerance for ORR. This work will pave the way for a new approach in the development of highly active and low-cost NPCs for fuel cells. 相似文献
33.
34.
Woohyun J. Moon Prof. Dr. Juewen Liu 《Chembiochem : a European journal of chemical biology》2020,21(3):401-407
It has been proposed that Mg2+ and Fe2+ are very similar in interacting with ribozymes and some protein-based enzymes, but their activities with DNAzymes have yet to be studied. Here, the activity of Fe2+ as cofactor for a few RNA-cleaving DNAzymes is investigated. 17E is a well-studied DNAzyme that is active in the presence of many different divalent metal ions; it is highly active with Fe2+ with an apparent Kd of 29.7±2.3 μm and a kobs of 1.12±0.11 min−1 in the presence of 1 mm Fe2+ at pH 7.5. Fe2+ has 21-fold higher activity than Mg2+. Six different DNAzymes are then tested, and only the DNAzymes active with Mg2+ (17E, 8–17, and E5) are active with Fe2+. Fe2+ has 25 and one- to twofold higher activity than Mg2+ for the 8–17 and E5 DNAzymes, respectively. In pH>7 buffer and in presence of air, 1 mm Fe2+ results in a nonspecific degradation of the DNA strand due to reactive oxygen species (ROS). Cleavage reactions in anoxic environment and antioxidant ascorbate can be used to overcome the effect of oxidation. The findings provide insights for potential DNAzyme catalysis in the early Earth, and they further support the similarity between Mg2+ and Fe2+ in enzyme catalysis. 相似文献
35.
肉桂是我国特色经济林树种,我国肉桂种植面积和年产量均居世界首位。我国肉桂主要分布在两广地区,其中广西为14.9万hm2,广东为8.9万hm2,两地面积占全国肉桂分布总面积的95%以上。肉桂既是著名的香料又是传统的名贵中药,具有极高的经济价值,发展肉桂产业对于促进农民增收、维护健康中国有着重要的意义。本研究综述了肉桂资源量、分布情况及主要利用部位,介绍肉桂主要产品(如桂皮,桂枝,肉桂粉及肉桂油)及加工技术现状、产品质量控制及其分析检测方法,分析了产业未来的发展趋势,并提出了产业发展的对策和措施:加强肉桂标准化示范基地建设,提高优质资源供给能力;提高肉桂加工利用技术水平,延长产业链;培育肉桂龙头企业,提高产品市场竞争力。为我国肉桂特色资源加工利用产业的可持续发展提供一定的思路。 相似文献
36.
37.
Milinda Pattanayak Md Nadim F Hoque Zhaoyang Fan Ayrton A. Bernussi 《Science and Technology of Advanced Materials》2018,19(1):693-701
We report large amplitude modulation waveforms as large as ~ 10 V using vanadium dioxide micro-channel devices operating under current-controlled conditions. The self-sustained electrical oscillations were generated by controlling the applied current in the negative differential resistance region of the investigated devices. An appropriate value of internal capacitance was achieved as parasitic capacitance in the device structure to stabilize the electrical oscillations. This eliminates the need of an external pulsed source or any external passive component connected to the micro-channel devices. Amplitude and frequency of the oscillation were tuned by illuminating the device micro-channel with an external laser. An equivalent circuit model was developed to simulate the waveforms. A good agreement between experiment and simulation was verified. 相似文献
38.
Chengyong Yang Bolong Huang Shuxing Bai Yonggang Feng Qi Shao Xiaoqing Huang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):2001267
Electrocatalytic nitrogen reduction reaction (NRR) is a promising process relative to energy-intensive Haber–Bosch process. While conventional electrocatalysts underperform with sluggish paths, achieving dissociation of N2 brings the key challenge for enhancing NRR. This study proposes an effective surface chalcogenation strategy to improve the NRR performance of pristine metal nanocrystals (NCs). Surprisingly, the NH3 yield and Faraday efficiency (FE) (175.6 ± 23.6 mg h–1 g–1Rh and 13.3 ± 0.4%) of Rh-Se NCs is significantly enhanced by 16 and 15 times, respectively. Detailed investigations show that the superior activity and high FE are attributed to the effect of surface chalcogenation, which not only can decrease the apparent activation energy, but also inhibit the occurrence of the hydrogen evolution reaction (HER) process. Theoretical calculations reveal that the strong interface strain effect within core@shell system induces a critical redox inversion, resulting in a rather low valence state of Rh and Se surface sites. Such strong correlation indicates an efficient electron-transfer minimizing NRR barrier. Significantly, the surface chalcogenation strategy is general, which can extend to create other NRR metal electrocatalysts with enhanced performance. This strategy open a new avenue for future NH3 production for breakthrough in the bottleneck of NRR. 相似文献
39.
Zhonghao XIE 《等离子体科学和技术》2020,22(8):85503
Tegillarca granosa (T. granosa) is susceptible to heavy metals, which may pose a threat to
consumer health. Thus, healthy and polluted T. granosa should be distinguished quickly. This
study aimed to rapidly identify heavy metal pollution by using laser-induced breakdown
spectroscopy (LIBS) coupled with linear regression classification (LRC). Five types of T.
granosa were studied, namely, Cd-, Zn-, Pb-contaminated, mixed contaminated, and control
samples. Threshold method was applied to extract the significant variables from LIBS spectra.
Then, LRC was used to classify the different types of T. granosa. Other classification models
and feature selection methods were used for comparison. LRC was the best model, achieving an
accuracy of 90.67%. Results indicated that LIBS combined with LRC is effective and feasible
for T. granosa heavy metal detection. 相似文献
40.
Yashvir Singh Abhishek Sharma Nishant Singh Amneesh Singla Pankaj Mohan Rastogi 《国际自然能源杂志》2020,41(13):1534-1547
ABSTRACT Fossil fuel resource is on the draining stage which leads to an increment in the cost of the petroleum products. Nowadays, research is focused on the development of environmental friendly lubricants which are derivatives of renewable sources. Inedible plant oil-driven bio-lubricants are environmentally friendly because they are non-hazardous, biodegradable, as well as there is no emission of toxic gases. This study involves the characterisations, advantages, as well as utilisation of inedible plant oil-driven bio-lubricants as an alternative for tribological applications. This report presents the status about the global lubricant market as well as potential outlook. Inedible plant oil-driven bio-lubricants bear high viscosity, high lubricity, and high viscosity index which can enhance the equipment service life and has the ability to carry high load and results in minimum amount of metal traces during combustion. 相似文献