镍系配合物催化乙烯选择性齐聚的研究进展

α-烯烃是一类可用于生产聚烯烃、合成润滑油、表面活性剂等产品的重要化工原料,目前主要通过乙烯齐聚工艺进行生产。在乙烯齐聚过程中,催化剂起着重要作用。在其催化剂的研究中,部分镍系配合物催化剂因表现出优良的催化性能及良好的发展和应用前景而受到重视。文中主要从配体结构如单齿型配体、双齿型配体、多齿型配体及产物选择性等方面介绍了镍系配合物催化乙烯齐聚的发展情况,阐述了近年来镍系催化剂已取得的突破和研究成果,展望了该领域未来的研究方向。

Identification and Analysis of the WRKY Transcription Factor Gene Family in Verbena bonariensis

The WRKY transcription factor gene family is one of the unique gene families in plants.It plays an important role in response to abiotic stresses such as cold and drought,hormone signal transduction,regulation of biosynthesis,leaf senescence seed germination,etc.However,little information is available about WRKY transcription factors in Verbena bonariensis.In this study,70 VbWRKY genes were identified from the whole genome.The phylogenetic analysis of the WRKY gene family in V.bonariensis and Arabidopsis shows that the WRKY genes in V.bonariensis can be divided into three groups:I,II,and III,which contain 13,47,and 10 members,respectively.Group II can be further divided into five subclasses:IIa(5),IIb(10),IIc(18),IId(6),and IIe(8).Conservative motif analysis showed that 64 proteins encoded by the VbWRKY gene had conserved motifs 1,2 and 3,and the same subclass motif elements were approximately the same.The collinearity analysis showed that there were 44 homologous gene pairs among the VbWRKYs,and these homologous gene pairs may have the same function.Promoter sequence analysis showed that the VbWRKY gene has multiple cis-acting elements,including not only cis-acting elements related to low-temperature and light responses,but also cis-acting elements related to hormone regulation,Among them,most VbWRKY genes contain response elements about low-temperature,and 30 VbWRKY genes contain low-temperature response elements(LTR),and 61 VbWRKY genes contain abscisic acid response elements(ABRE),indicating that VbWRKY plays a crucial role in plant growth and abiotic stress.According to the expression of VbWRKY in the cold stress and different tissues transcriptome,70 VbWRKY genes played their respective roles in various tissues and stages to regulate plant growth,Also,some of them participated in the process of cold stress tolerance,52 VbWRKYs showed significant differences in expression under cold stress,and 37 VbWRKY genes were up-regulated under cold stress.9 VbWRKY genes were selected for quantitative real-time PCR(qRT-PCR)analysis under low-temperature stress,and the results showed that all 9 genes were upregulated under low-temperature stress.Ultimately,the present study provides a comprehensive analysis of the predicted V.bonariensis WRKY genes family,which provided a theoretical basis for the study of low-temperature resistance and growth and development of V.bonariensis.

单原子改性二硫化钼电催化析氢

氢能是21世纪最理想的清洁能源之一。相比于天然气和煤炭制氢,电解水制氢具有成本低、效率高、无污染、原料丰富的特点,可以有效缓解CO;过量排放导致的温室效应。电催化析氢需要活性高、稳定性好、廉价易得的催化剂克服反应能垒并加速动力学过程,对实现分解水制氢的规模化应用具有重要的推动作用。铂基催化剂被公认为性能最优异的析氢电催化剂之一,但由于丰度低、成本高,不适用于大规模产氢。二硫化钼(MoS;)作为典型的二维材料之一,因其高活性位点暴露和高比表面积在析氢领域展现出一定的应用潜能,并有望取代铂基催化剂。本文基于MoS;电催化剂在析氢领域的研究现状,对单原子掺杂改性MoS;以提高其催化活性的研究进行了综述,以析氢过电位(Overpotential)及塔菲尔(Tafel)曲线斜率为依据,总结了贵金属单原子、非贵金属单原子及非金属单原子改性MoS;催化剂的结构与性能以及它们之间的构效关系,在此基础上,提出MoS;析氢催化剂目前存在的科学问题并指出了未来的努力方向。

Influence of calcination temperature for LaTi0.2Fe0.8O3 on catalytic pyrolysis of bagasse lignin

LaTi(0.2)Fe(0.8)O3(LTF)was prepared by the sol-gel method,and the effects of calcination temperature on the structure and properties were investigated,A new method of preparing aryl oxygen-containing compounds from bagasse lignin(BL)by the catalytic pyrolysis over LTF was proposed.The results show that LTF has cubic crystal phase and porous structure and its optimal calcination temperature is 800℃(LTF-800).In the test for catalytic pyrolysis of BL,with the addition of LTF-800,the yield of liquid product reaches the maximum;the contents of phenolics,guaiacols,syringols,phenylates and furans increase obviously,while those of benzenes,esters and carboxylic acid decrease.The total content of aryl oxygencompounds(including phenolics,guaiacols,syringols and phenylates)in liquid product is more than 74 wt%with the addition of LTF-800,larger than that obtained by single BL pyrolysis(62 wt%).LTF could avoid oxygen-containing functional groups from being excessively destroyed.It has nice regeneration performance by controlled combustion of char even after 5 cycles.

“1+1>2”:Highly efficient removal of organic pollutants by composite nanofibrous membrane based on the synergistic effect of adsorption and photocatalysis

Adsorption and photocatalysis are regarded as two desirable technologies for wastewater remediation,but are still unsatisfactory in removal effect,eco-friendly regeneration and facile reusability.In this study,we developed a composite nanofibrous membrane material with excellent removal performance for organic pollutants based on synergistic adsorption and photocatalysis.A novel boron-doped,nitrogen-deficient graphitic carbon nitride(B-C3N4)photocatalyst as well as an amphiphilic copolymer of methyl methacrylate and acrylic acid(p(MMA-AA))were synthesized respectively,and then used to modify polyethersulfone for the fabrication of composite nanofibrous membrane with improved hydrophilicity,negativelycharge property and enhanced visible light response simultaneously.Subsequently,the synergistic effect of adsorption and photocatalytic degradation for organic pollutants were identified especially and resulted in an excellent removal efficiency even superior to the combination of adsorption and photocatalytic degradation,which could be called a“1+1>2”effect.In addition,the regeneration and reusability,the purification ability for multicomponent wastewater,and the photocatalytic mechanism,were investigated and discussed systematically.In this work,we not only prepared the nanofibrous membrane with synergistic effect of adsorption and photocatalysis,but also provided a versatile approach to design dualfunctional support material to ensure the practical applications of powdery photocatalyst in wastewater treatment.

A triple-combination nanotechnology platform based on multifunctional RNA hydrogel for lung cancer therapy

Conventional cancer combination therapy usually involves systemic delivery of anticancer drugs which may lead to the destruction of normal cells and physiological toxicity due to the lack of targeting ability and toxicity of drug carriers. In the present study, a triple combination nanosystem of gene therapy, chemotherapy and phototherapy delivered by multifunctional RNA nanohydrogels(RNA NHs) was established. By taking the advantages of DNA nanotechnology and rolling circle transcription(RCT), three lung cancer inhibitor microRNA(let-7 a, microRNA 34 a, microRNA 145) hairpins were integrated in one RNA NH nanoparticle, leading to the simultaneous silencing of three targeted m RNAs. Meanwhile, RNA NH carried doxorubicin(DOX, a chemotherapy drug) as well as 5,10,15,20-tetrakis(1-methylpyridinium-4-yl) porphyrin(TMPyP4, a photosensitizer) and delivered these drugs to cancer cells. It was demonstrated that lung cancer inhibitor microRNAs integrated in RNA NHs, DOX and TMPyP4 could play a synergistic anti-cancer role in multi-drug resistance cancer cells. Under the action of aptamer sequence S6 that was modified with cholesterol, the resulting RNA NHs were condensed to feasible size without the assistance of polyelectrolyte condensation reagents and showed cancer-specific cellular targeting. Subsequently, thousands of copies of miRNA together with chemotherapy drug as well as photosensitizer were delivered to cancer cells specifically, and an ideal synergistic treatment effect was achieved in vivo, thus playing a combined role of gene therapy, chemotherapy and phototherapy. Through this study, it can be concluded that the triple combination therapy nanosystem can overcome the multidrug resistance caused by the malfunction of genes in chemotherapy and shows a great potential in the field of multifunctional synergistic cancer treatment.

Optically anisotropic,electrically tunable microlens arrays formed via single-step photopolymerization-induced phase separation in polymer/liquid-crystal composite materials

Microlenses or arrays are key elements in many applications.However,their construction methods involve multiple fabrication processes,thereby increasing the complexity and cost of fabrication.In this study,we demonstrate an optically anisotropic,electrically tunable liquid crystal(LC)microlens array using a simple,one-step fabrication method.The microlens array is formed via photopolymerization-induced phase separation inside a polymer/LC composite.It possesses both polarization-dependent and electrically tunable focusing and imaging properties.Without applying voltage,the microlens array has a natural focal length of 8 mm,which is a result of its inherent gradient refractive index profile.Upon applying voltage above the threshold,the LC molecules reorient along the electric field direction and the focal length of the microlens array gradually increases.Based on its superior properties,the microlens array is further used for integral imaging applications,demonstrating electrically tunable central depth plane.Such LC microlens arrays could find numerous potential applications owing to their advantageous features of being flat,ultra-thin,and tunable,including 3D displays,optical interconnects,and more.