The Effect of Bio-Synthesized Silver Nanoparticles on Germination,Early Seedling Development,and Metabolome of Wheat (Triticum aestivum L.)

Changes in the metabolome of germinating seeds and seedlings caused by metal nanoparticles are poorly understood. In the present study, the effects of bio-synthesized silver nanoparticles ((Bio)Ag NPs) on grains germination, early seedlings development, and metabolic profiles of roots, coleoptile, and endosperm of wheat were analyzed. Grains germinated well in (Bio)Ag NPs suspensions at the concentration in the range 10–40 mg/L. However, the growth of coleoptile was inhibited by 25%, regardless of (Bio)Ag NPs concentration tested, whereas the growth of roots gradually slowed down along with the increasing concentration of (Bio)Ag NPs. The deleterious effect of Ag NPs on roots was manifested by their shortening, thickening, browning of roots tips, epidermal cell death, progression from apical meristem up to root hairs zone, and the inhibition of root hair development. (Bio)Ag NPs stimulated ROS production in roots and affected the metabolic profiles of all tissues. Roots accumulated sucrose, maltose, 1-kestose, phosphoric acid, and some amino acids (i.e., proline, aspartate/asparagine, hydroxyproline, and branched-chain amino acids). In coleoptile and endosperm, contrary to roots, the concentration of most metabolites decreased. Moreover, coleoptile accumulated galactose. Changes in the concentration of polar metabolites in seedlings revealed the affection of primary metabolism, disturbances in the mobilization of storage materials, and a translocation of sugars and amino acids from the endosperm to growing seedlings.     

Heteroctanuclear Au4Ag4 Cluster Complexes of 4,5-Diethynylacridin-9-One with Luminescent Mechanochromism

Two heteroctanuclear Au₄Ag₄ cluster complexes of 4,5-diethynylacridin-9-one (H₂L) were prepared through the self-assembly reactions of [Au(tht)₂](CF₃SO₃), Ag(tht)(CF₃SO₃), H₂L and PPh₃ or PPh₂Py (2-(diphenylphosphino)pyridine). The Au₄Ag₄ cluster consists of a [Au₄L₄]⁴⁻ and four [Ag(PPh₃)]⁺ or [Ag(PPh₂Py)]⁺ units with Au₄L₄ framework exhibiting a twisted paper clip structure. In CH₂Cl₂ solutions at ambient temperature, both compounds show ligand fluorescence at ca. 463 nm as well as phosphorescence at 650 nm for 1 and 630 nm for 2 resulting from admixture of ³IL (intraligand) of L ligand, ³LMCT (from L ligand to Au₄Ag₄) and ³MC (metal-cluster) triplet states. Crystals or crystalline powders manifest bright yellow-green phosphorescence with vibronic-structured emission bands at 530 (568sh) nm for complex 1 and 536 (576sh) nm for complex 2. Upon mechanical grinding, yellow-green emission in the crystalline state is dramatically converted to red luminescence centered at ca. 610 nm with a drastic redshift of the emission after crystal packing is destroyed.     

以树形分子为模板制备银纳米颗粒

以硝酸银为原料,硼氢化钠为还原剂,PAMAM树形分子为模板兼稳定剂,制备出粒径分布范围在4～7mm的银纳米颗粒．实验发现,其他条件相同时,银纳米颗粒的粒径随着Ag^ ／树形分子摩尔比的增加而增加,并且树形分子代数越高,所起的模板作用越显著．还研究了溶液pH值的影响,发现当溶液pH值在7左右时,可以制得粒径较小、分散性较好的银纳米颗粒．用紫外-可见光谱,透射电镜(TEM)以及原子力显微镜(AFM)等测试手段对所制得的银纳米颗粒进行了表征．     

氯化银立方体微晶乳剂和{100}面扁平微晶乳剂的甲酸盐掺杂增感

将甲酸盐掺杂在乳剂微晶不同位置处,制备成氯化银立方体微晶乳剂和{100}面扁平微晶乳剂.实验发现:作为正空穴捕获剂,适当计量的甲酸盐在不增加乳剂灰雾的前提下,可使上述乳剂的感光度提升3—8倍.甲酸盐在两种晶形乳剂的不同位置掺杂的研究结果显示,甲酸盐均匀掺杂可比表面掺杂获得更高的感光度.在两种乳剂中甲酸盐掺杂增感都可与其后的硫增感、硫加金增感以及光谱增感协同作用,进一步提升乳剂的感光性能.     

聚酰胺富集吸光光度法测定银

聚乙内酰胺作为Ａｇ的富集剂，从稀ＨＮＯ３溶液中富集Ａｇ具有吸附速度快，解脱容易，吸附容量大且可重复使用等优点。在选择条件下，最大吸附容量达５０ｍＬ／ｍｉｎ，并作１８种元素干扰实验确定允许量。     

CROSS-LINKING OF AROMATIC POLY（THIOETHER）S

A novel cross-linking process using two high molecular weight aromatic poly(thioether)s,which were synthesized by the reactions of 4,4′-thiobisbenzenethiol with 4,4′-difluorobenzophenone and 4,4′-difluorodiphenylsulfone,respectively, and commercially available lower molecular weight poly(p-phenylene sulfide)was investigated.These reactions were carried out in bulk by the addition of silver tetrafluroborate andα,α′-dibromo-p-xylene at 190℃over a period of 45 min. Furthermore,the same procedure could be modified to cross-link compression-molded films of these three polymers.The thermal and solubility behaviors of these polymers before and after cross-linking reactions,are presented.     

Ag/PANI/Fe_2O_3复合纳米粒子的合成与催化性能

借助于PANI的还原性质,PANI/Fe2O3复合载体与AgNO3发生表面氧化还原反应,合成了Ag/PANI/Fe2O3复合纳米粒子。TEM和XRD结果表明,立方晶系纳米银的平均粒径10nm。FTIR结果表明,Ag与PANI及Fe2O3复合载体之间不存在化学键合作用,但由于PANI与Ag之间的电子相互作用,Ag/PANI/Fe2O3复合纳米粒子的FTIR吸收峰发生蓝移。Ag/PANI/Fe2O3复合纳米粒子对于间硝基苯磺酸钠的硼氢化钠还原反应表现出良好的催化活性,30min内间硝基苯磺酸钠的转化率达到86.77%。     

Ag3PO4的可见光光催化性能及机理分析

采用沉淀置换法制备了可见光光催化剂Ag3PO4,利用XRD、UV-Vis及XPS等对其进行了结构特性分析,以水中微污染有机物的降解评价了Ag3PO4的光催化活性,并通过活性物种及能带结构的分析对催化剂的光催化机理进行了推测。结果表明,Ag3PO4的带隙能约为1.9 eV、催化剂表面存在的Ag+可捕获光生e-、催化剂的价带电位较低,这有利于Ag3PO4在可见光照射下产生的e--h+的分离及活性物种.OH的形成。经60 min可见光光催化反应,15 mg.L-1的甲基橙和腐殖酸的降解率分别达97%和82%,比同等条件下TiO2-P25的降解率还高40%和25%,光催化剂Ag3PO4的用量为0.6 g.L-1。