Screening the Key Region of Sunlight Regulating the Flavonoid Profiles of Young Shoots in Tea Plants (Camellia sinensis L.) Based on a Field Experiment

Both UV and blue light have been reported to regulate the biosynthesis of flavonoids in tea plants; however, the respective contributions of the corresponding regions of sunlight are unclear. Additionally, different tea cultivars may respond differently to altered light conditions. We investigated the responses of different cultivars (‘Longjing 43’, ‘Zhongming 192’, ‘Wanghai 1’, ‘Jingning 1’ and ‘Zhonghuang 2’) to the shade treatments (black and colored nets) regarding the biosynthesis of flavonoids. For all cultivars, flavonol glycosides showed higher sensitivity to light conditions compared with catechins. The levels of total flavonol glycosides in the young shoots of different tea cultivars decreased with the shade percentages of polyethylene nets increasing from 70% to 95%. Myricetin glycosides and quercetin glycosides were more sensitive to light conditions than kaempferol glycosides. The principal component analysis (PCA) result indicated that shade treatment greatly impacted the profiles of flavonoids in different tea samples based on the cultivar characteristics. UV is the crucial region of sunlight enhancing flavonol glycoside biosynthesis in tea shoots, which is also slight impacted by light quality according to the results of the weighted correlation network analysis (WGCNA). This study clarified the contributions of different wavelength regions of sunlight in a field experiment, providing a potential direction for slightly bitter and astringent tea cultivar breeding and instructive guidance for practical field production of premium teas based on light regimes.     

Cu/SO42-/La2O3-ZrO2-Al2O3催化剂的制备及其对C3H6选择还原NO的催化性能

以Al₂O₃为基质，添加ZrO₂和La₂O₃，制成La₂O₃-ZrO₂-Al₂O₃复合载体，然后采用SO₄^2-进行改性，再负载上Cu²⁺，制备了铜基SO₄^2-改性的复合载体催化剂(Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃)。考察了它在富氧条件下对丙烯选择还原NO的催化性能，并借助XRD、SEM、TG、Py-IR、NH₃-TPD、FTIR和TPR等方法研究了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃的结构和性能的关系。结果表明，ZrO₂的加入主要有利于提高催化剂的低温活性；La₂O₃的加入则主要有利于提高催化剂的热稳定性和还原性能；SO₄^2-能够与Zr形成螯合双配位结构，大幅度促使催化剂表面酸量增加并且酸性增强；因此，有效地提高了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃在富氧条件下对丙烯选择还原NO的催化活性和水热稳定性。在无水条件下，Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃能使NO的最大转化率高达84.3%，即使在275 ℃ 10%水蒸气存在的情况下，仍能使NO的转化率高达81.2%。     

化学微观表征的方法与教学策略

将化学宏观现象进行形象、直观与动态的微观表征,能激发学生的学习兴趣,协助学生理解化学原理与规律。在几种不同形式的微观表征方法中,微观表征图能有效地消除相异构想,是建构化学三重表征的突破口,有利于化学三重表征的转化与融合。     

Preparation and characterization of nickel hydroxide microspheres assembled by nanoribbons

Abstract  

This article describes a facile green strategy for preparing the Ni(OH)₂ microsphere assembled by nanoribbons by the template of the squama inner coat of onion at mild condition. The method is simple and effective. The results of SEM show the products are Ni(OH)₂ microspheres with diameters in the range of 500–2,500 nm. The results of TEM show the microsphere is assembly by nanoribbons, with thickness in the range of 30–50 nm. The products were characterized by powder X-ray diffraction, IR, and thermogravimetric analysis. A possible formation mechanism was also proposed.     

仿生支撑液膜法制备硫化锌自组装纳米球链

采用了一种全新的化学仿生方法——载体支撑液膜法制备ZnS纳米球链. 常温常压条件下, 利用含邻菲罗啉载体的支撑液膜(SLM)反应体系选择性传输Zn^2＋至膜另一侧, 在SLM模板作用下, 控制结晶位点, 定向结合阴离子, 加上局部过饱和及界面成核的影响, 成功制备出由8～30 nm纳米粒子自组装的直径范围为250～300 nm ZnS球链. 由XRD和TEM的结果显示, 其结构为立方闪锌矿, 晶格常数为α＝0.5390 nm. 本文还对其荧光性质及产物形成机理进行了初步探讨.     

分布式冷热电三联供系统的单耗分析模型研究

基于"单耗分析"理论,建立了针对燃料为天然气的分布式冷、热、电三联产系统的常见运行模式下的多热源、多冷源的燃料单耗模型和成本单耗模型.利用该模型进行了案例计算,结果清楚地表明了系统各个环节燃料附加单耗的分布.通过对计算结果的分析,得出了一些有益的结论.     

Preparation, structures and photoluminescent enhancement effect of PbWO4–TiO2 composite nanofilms

A novel route for preparing PbWO₄–TiO₂ nanofilms on a glass substrate is firstly proposed. The collodion is used as a dispersant and film-forming agent. The nanofilms are characterized through SEM, XRD, TG/DTA, PL and IR, respectively. The results of XRD indicate PbWO₄ particles with tetragonal scheelite structure and TiO₂ particles with Anatase phase, and SEM shows they are well dispersed in the substrate. Compared with nanoparticles, when TiO₂ nanoparticles are added in 5% ratio, the PL intensities at 395 nm of PbWO₄ nanofilms are enhanced obviously. IR spectrum reveals a large absorption band between 750 and 870 cm⁻¹, which is the W–O stretching vibration in WO₄ tetrahedron.     

Facile synthesis of monodisperse silver nanoparticles by bio-template of squama inner coat of onion

This paper describes a facile sy]nthetic method for preparing monodisperse silver nanoparticles by bio-template of the squama inner coat of onion. The method is able to make silver nanoparticles with average diameters in the range of 4.6–7.9 nm with narrow size distribution. The important factors in the synthesis of monodisperse silver nanoparticles were discussed. The nanoparticles were characterized by transmission electron microscope, Powder X-ray diffraction and UV-Vis spectroscopy. A possible formation mechanism was also proposed. Because of its simple apparatus, high yield, convenient operation and mild conditions, this synthetic method will have potential application in preparing nanoparticles.     

One-step synthesis and antibacterial property of water-soluble silver nanoparticles by CGJ bio-template

In this article, a new synthetic method of nanoparticles with fresh Chinese gooseberry juice (CGJ) as bio-template was developed. One-step synthesis of highly water-soluble silver nanoparticles at room temperature without using any harmful reducing agents and special capping agent was fulfilled with this method. In the process, the products were obtained by adding AgNO₃ to CGJ, which was used as reducing agent, capping agent, and the bio-template. The products of silver nanoparticles with diameter of 10–30 nm have strong water solubility and excellent antibiotic function. With the same concentration 0.047 μg mL⁻¹, the antibacterial effect of water-soluble silver particles by fresh CGJ was 53%, whereas only 27% for silver nanoparticles synthesized using the template method of fresh onion inner squama coat (OISC). The excellent water solubility of the products would enable them have better applications in the bio-medical field. The synthetic method would also have potential application in preparing other highly water-soluble particles, because of its simple apparatus, high yield, mild conditions, and facile operation.     

微孔树脂镶嵌的α-Fe2O3纳米粒子催化苯酚过氧化氢羟化研究

由于特殊的尺寸效应,纳米材料的晶粒间界面在整个材料中占有极大比例,这使其表现出与同质常规固体材料完全不同的物理化学性质［１］．纳米材料的这种特殊性质在催化反应中往往会表观出异常的催化活性［２］．微孔树脂由于材料不同,在其孔道结构内会形成不同的微环境,...