Enzymatic electrosynthesis as an emerging electrochemical synthesis platform

Enzymatic electrosynthesis (EES), combining enzymatic catalysis and electrochemical techniques for the production of desired chemicals, has gained prominence because of its use of clean electrical energy inputs and highly specific enzyme biocatalysts and its capability of performing complicated reactions with high yield. In this review, we summarize the most recent state-of-the-art advances in EES and recognize that the research emphasis has shifted from CO₂ reduction to the utilization of N₂ and the synthesis of high-value products. Particular attention is given to the energy sources for powering EES, including direct electrical energy, light energy, and chemical energy obtained from self-powered biosystems. Enzyme-based hybrid systems integrated with microbial or chemical approaches are also presented. Finally, key challenges and future directions of EES are discussed briefly.     

Selectfluor-mediated mono-C–H activation: The syntheses of mono-ortho-substituted anilides

The C–H activation of aryl amide using readily available Pd(OAc)₂ in the presence of selectfluor is reported. The highly mono-selective introduction of sp² hybridized functional groups have been realized. A broad range of aryl-, alkenyl- and keto-aryl amides were prepared using unactivated coupling partners under mild conditions.     

Synthesis and characterization of NaA zeolite particle as intumescent fiame retardant in chloroprene rubber system

NaA zeolite with average particle size of 1 m was successfully synthesized by microwave heating. Inu-ences of pre-crystallization time,microwave power and microwave heating time on the synthesis of NaA zeolite were investigated. The as-synthesized sample was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and particle size distribution(PSD) . Thermal and fiame retardant properties as intumescent fiame retardant(IFR) in chloroprene rubber(CR) system,such as thermo-gravimetry(TG),lim...     

Discussion of the Drop Rest Phenomenon at Millimeter Scale and Coalescence of Droplets at Micrometer Scale

Adsorption of surfactants at water-oil interfaces is of great importance in the coalescence of drops and stability of emulsions. In this work, we have studied the adsorption of nonionic surfactants Span 80 at water-oil interfaces and its influence on the drop rest phenomenon and W/O emulsion stability in a pulsed DC electrical field. The variation of interfacial tension with the concentration of surfactant was studied and the data were fitted using a surface equation of state derived from the Langmuir adsorption isotherm. A stochastic model for coalescence was used to fit the coalescence time distributions. The significance of the model parameters was discussed. The stability of the emulsion was evaluated by conductivity methods. The researches in this article indicated that both of the rest time distribution of the drops at the interface and stability of the emulsion in the electrical field was significantly affected by surfactant concentration.     

Monomer-dependent synthesis of secondary amine-linked triazine-based two-dimensional polymers nanosheets

Expanding the structural diversity of crystalline two-dimensional polymers(2DPs) is highly desired but remains a considerable challenge. Herein we report the first synthesis of novel crystalline secondary amine-linked triazine-based 2DPs(SAT-2DPs) by using benzidine or 4, 4′′-diamino-p-terphenyl and cyanuric chloride under solvothermal conditions. We find the structures of diamine-based monomers play a crucial role in deciding whether the synthesized material is crystalline 2DPs nanosheets or amorphous nanoparticles, which is unexpected and provides an important understanding of the 2D polymerization mechanism.The obtained SAT-2DPs not only show a lateral size of micrometers and an ultrathin thickness of a few nanometers, but also demonstrate high crystallinity with a unique ABC stacking configuration, excellent solvent dispersibility and superior thermal stability. In addition, the resultant SAT-2DPs are used to guide uniform lithium-ion deposition due to their abundant nitrogen atoms and ordered open channels. The assembled asymmetric coin cells(Li|Cu) with SAT-2DPs realize the average coulombic efficient up to 99.3% during discharge-charge cycles. This work provides valuable insights into the synthesis of new 2DPs for various applications.     

SPSS软件对铁矿中微量元素含量的统计分析

利用SPSS软件从统计学描述、正态分布检验、回归和相关分析、聚类分析和因子分析等方面对铁矿中微量元素含量特点进行了研究。分析结果表明:根据抽样样本,铁矿中11种微量元素含量均不符合正态分布特征,异常值分布矿种相对集中,重金属和硫及卤素之间的相关程度高,同时根据因子综合得分对矿种进行了分类,为铁矿品质评价和合理利用提供了一定的参考。     

Energy accumulation effect and parameter optimization for fabricating of high-uniform and large-area period surface structures induced by femtosecond pulsed laser

In this paper, theoretical and experimental investigations are performed to understand the effect of laser energy accumulation on morphologies of femtosecond laser-induced periodic surface structures (LIPSSs). Based on energy accumulation effect we put forward, scanning velocity, distance of two adjacent scan lines and pulsed laser energy density are optimized to fabricate high-uniform and large-area period surface structures for the first time. Our theoretical results can offer clues to choose experiment parameters in order to obtain high-quality LIPSSs which have extensively emerging and potential applications in optoelectronics, phononics and so on.     

ON MEROMORPHIC SOLUTIONS OF RICCATI AND LINEAR DIFFERENCE EQUATIONS

In this paper, meromorphic solutions of Riccati and linear difference equations are investigated. The growth and Borel exceptional values of these solutions are discussed, and the growth, zeros and pol...     

Rich dynamics caused by delay in a nonchaotic Rulkov map

This paper proposes a new nonlinear control scheme incorporating a state observer, a fuzzy neural network (FNN) and a new Nussbaum function for strict-feedback nonlinear systems by considering several challenges. These challenges are external disturbances, uncertain dynamics, unmeasured states, constrained input, unknown control direction, singularity issue, and actuator’s faults of different types. The scheme uses approximations of the unknown system’s dynamics provided by the FNN, the system’s states variables estimation provided by a model-free high-gain observer, and the control direction provided by the Nussbaum function. Compared to existing schemes, in addition to the fact that the new scheme can tackle simultaneously all the aforementioned challenges with better tracking performances, it also cancels the assumption about the positive definiteness of the control gain function found in many works. Thus, the scheme suites for more applications as it can be applied in cases where the control gain can be either semi-negative/negative-definite, semi-positive/positive-definite. Furthermore, the knowledge of the bounds for uncertain dynamics, actuation faults, FNN approximation errors and external disturbances is not required as it is for many other schemes. The effectiveness of the scheme is illustrated by its successful application to three examples, which are the pitch angle control for a Boeing 747-100/200 represented by the ultimate approximate nonlinear longitudinal model over up-and-away flight regime, the trajectory tracking control of a one-link manipulator actuated by a brush DC (BDC) motor, and the position tracking control for an inverted pendulum.     

ON DIFFERENCE EQUATIONS RELATING TO GAMMA FUNCTION

We consider the existence, the growth, poles, zeros, fixed points and the Borel exceptional value of solutions for the following difference equations relating to Gamma function y(z + 1) -y(z) = R(z) and y(z + 1) = P (z)y(z).