Shell microlaminations of the freshwater bivalveHyridella depressa as an archival monitor of manganese water concentration: Experimental investigation by depth profiling using secondary ion mass spectrometry (SIMS)

Specimens of the freshwater unionid bivalveHyridella depressa were experimentally exposed to a synthetic river water containing an elevated Mn water concentration (20 mg l^–1) for 2 or 6 days. SIMS depth profiles through the incremental nacre microlaminations or tablets (0.6 m breadth) of the shells of these bivalves showed increases in the signal intensity of Ca-normalised Mn that corresponded to the period of exposure. These results support the proposition that bivalve shells can be used as retrospective monitors of water chemistry. They also indicate that 1) there is a lag phase between exposure to the elevated Mn water concentration and its expression in the shell, and 2) the period for Mn in the shell to reach equilibrium with the aquatic medium is greater that 2 to 6 days.     

基于层状磷酸锰-金纳米颗粒复合物的电化学传感器研究

利用化学沉淀方法室温下水相合成层状磷酸锰纳米材料.然后利用磷酸锰-金纳米颗粒修饰玻碳电极,构建电化学传感器并用于多巴胺的灵敏检测.通过循环伏安法和微分脉冲伏安法对所构建传感器的电化学行为进行考察.结果表明,该传感器对多巴胺的线性检测范围为0.5~120μmol/L,检出限为0.05μmol/L.同时,该方法具有灵敏度高、抗干扰能力强、稳定性好等优点.     

锰球制备条件对氮化反应的影响

利用自制的密闭氮化系统研究不同制备条件的锰球的氮化反应.考察锰粉粒度、成球压力和黏结剂添加量对氮化反应的影响,并测量锰球氮化过程中实时增重和温度曲线.实验结果表明:锰粉粒度由16 ～40目变成60 ～ 80目时,球心温度到达峰值的时间由164 s缩短为101s,球心最大温升由147℃增至233℃,氮化1h的转化率由90.81％增至93.64％;成球压力由266 MPa增至443 MPa,球心峰值温度将提前89 s到达,球心最大温升将提高22℃,氮化1h的转化率由91.59％增至94.92％;黏结剂添加量由1 g增至3 g,氮化1h的转化率由92.90％降至89.80％;正态对数分布的概率密度函数可用来近似拟合转化速率与时间的关系.     

聚天冬氨酸锰（Ⅱ）对干旱胁迫下菠菜抗氧化酶活性和MDA含量的影响

为研究聚天冬氨酸锰（Ⅱ）对植物抗旱性的影响,使用不同浓度的聚天冬氨酸锰（Ⅱ）分别对菠菜种子和幼苗进行处理。结果表明：在模拟干旱条件下,用0.1 mg/L聚天冬氨酸锰（Ⅱ）浸种,在试验浓度范围内促进菠菜发芽的效果显著。浸种及叶面喷施使菠菜叶片宽度、SOD、POD和CAT酶的活性均有增高,并且对MDA的产生有抑制作用。在试验浓度范围内12.5 mg/L浓度的聚天冬氨酸锰（Ⅱ）对菠菜叶面喷施效果显著。用聚天冬氨酸锰（Ⅱ）模拟物作为一种植物生长调节剂对菠菜浸种和叶面喷施能有效促进菠菜发芽和提高幼苗期菠菜抵抗干旱的能力。     

CaMnO_3和LaMnO_3的电子结构研究

密度泛函理论(DFT)方法通常难以处理强关联体系,而DFT+U方法的计算结果强烈地依赖于U的取值.利用一种混合了部分DFT交换关联势和非局域Hartree-Fock精确交换势的杂化泛函HSE方法,研究了钙钛矿锰氧化物的两个典型反铁磁绝缘体CaMnO3和LaMnO3的电子结构,分析了二者的能隙特征与Mn离子价态和磁有序态的关联.根据ZSA方案CaMnO3可划分为电荷转移型绝缘体.LaMnO3的能隙表现出各向异性特征,其中沿c轴方向及ab面内的自旋多数通道中能隙的Mott-Hubbard特征更为显著,而自旋少数通道显示出完全的电荷转移型特征.     

Hardness of Mn2V2O7 thin films and its influential factors

Mn2V2O7 thin films were deposited onto amorphous glass substrates using a chemical bath deposition method and different deposition time. X-ray diffraction (XRD) analysis was used to define the structure of the films. Their roughness, thickness, and surface properties were evaluated through atomic force microscopy (AFM). The hardness of the films was measured using a nanohardness tester. The film thickness, average grain size, and roughness were positively correlated with each other. These three parameters were observed to increase with the deposition time. The film thickness and average grain size were inversely correlated with the hardness and rough-ness. In addition, the number of crystallites per unit area and the dislocation density were observed to be positively correlated with the hardness and roughness. This study was designed to elucidate and formalize the underlying reasons for these relationships.     

自牺牲模板法合成Mn_2O_3纳米管

文章以-βMnO2纳米管作为自牺牲模板,在空气中550°C煅烧90 min,首次合成了立方相Mn2O3(c-Mn2O3)纳米管。用X-射线衍射、透射电子显微镜、选区电子衍射、场发射扫描电子显微镜及高分辨透射电子显微镜等对所制备的样品进行表征。结果表明,所制备样品为纯相的单晶c-Mn2O3,直径为200~500 nm,长度可达几微米。     

铁合金中钼、镍、锰、硅、磷量的快速测定研究

提出铁合金(生铁、铸铁、球铁)中钼、镍、锰、硅、磷快速测定方法:采用混酸快速溶解样品并制成系统分析母液,然后从中分取部分试液分别进行快速、简便、准确的单项测定,实现铁合金厂及铁铸件加工厂的生产例行分析及材料的快速检验,从而达到控制产品质量、降低化验成本和提高经济效率的目的。     

钛白废盐制备高纯MnO_2纳米棒

以钛白生产中产生的废盐为原料,采用水热法合成制备了高纯MnO2纳米棒,研究了不同反应条件对产品纯度和产率的影响.以纯度和产率为指针,确定了制备高纯MnO2纳米棒的最佳工艺条件,并对样品进行了XRD、FT-IR、SEM、ICP表征.研究结果表明,MnO2纳米棒的纯度随水热反应pH增大而增大,当pH为2.0时,制得的MnO2纳米棒纯度最大,继续增大pH,样品纯度下降,MnO2纳米棒的产率随水热反应pH增大而增大,当pH为4.0时,产率最大,继续增大pH,产率下降;当NaCl的加入量为0.08 g时,纯度和产率同时达到最大;MnO2纳米棒纯度几乎不随NaClO3加入量的变化而变化,而产率随着NaClO3加入量的增加而增加.     

尖晶石锰酸锂电池容量衰减的机理探析

尖晶石型锰酸锂的容量衰减是限制其大规模应用的瓶颈问题。现有观点认为二价锰离子在阳极上还原成金属锰,催化电解质分解、毒化固体电解质界面(SEI)膜,造成了锰酸锂体系锂离子电池的容量衰减。但最新研究确定锰元素是以二价的锰沉积在阳极上,并没有被还原成金属锰。本研究介绍国内外锰系锂离子电池容量衰减的研究进展,并在"沉积阳极上的锰氧化态是+2价"这个新发现的基础上,结合分析其它文献的实验数据,归纳总结出"二价锰离子与阳极SEI膜中的活性锂离子进行离子交换而沉积在阳极上,阻碍、堵塞活性锂离子的自由进出,从而引起锂离子电池容量衰退"新观点。