195Pt-NMR evidence of a low lying non-linear excitation in the linear conductor K2Pt(CN)4Br0.33.2H2O

¹⁹⁵Pt-NMR line shift, linewidth and relaxational behavior in the temperature range 4–120 K indicate a solitary excitation with an activation energy of about $\text{E}{}_0\text{k}\text{= 295}\text{K}$.     

Rotational motion of F− off-center defects in NaBr

The correlation time τ of the rotational motion of dilute F^? off-center defects in NaBr single crystals was studied by nuclear spin relaxation between 1.4 and 70 K. Above 15 K, the motion was found to be thermally activated with an activation energy of 110 K. Below 15 K, a deviation from the Arrhenius behavior was observed, which results in a linear relation τ ∝ 1/T for T < 8 K. The data were interpreted in the framework of phonon-assisted tunneling models.     

NMR investigation of defect properties in single crystal SrTiO3

Abstract

⁴⁹Ti and ⁸⁷Sr nuclear magnetic resonance measurements were performed in single crystalline SrTiO₃ between 90 K and 1800 K at various oxygen partical pressures. The NMR lines are found to be shifted with rising temperature due to oxygen vacancies acting as donors. Furthermore, three distinct motion-induced nuclear spin relaxation rates could be observed. The corresponding jump rates are attributed to the following processes: translational jumps of charged oxygen vacancies between oxygen sites, localized motion of oxygen vacancies in Fe-vacancy complexes, self diffusion of Sr²⁺.     

ICP-AES法测定内蒙古地区六种沙生木本植物中金属元素

采用ICP-AES法分别对内蒙古地区梭梭、小叶锦鸡儿、沙冬青、红柳、沙枣和沙柳等六种沙生木本植物中金属元素进行了测定和分析。该方法的加标回收率为94.98％～120.25％,RSD＜3.4％,具有良好的准确度和精密度。结果表明,常量元素Ca,K,Mg,Na,Al及植物生命活动所必需的微量元素Fe,Mn,Cu,Zn在六种沙生木本植物中表现为不同的含量顺序,且Fe,Mn,Cu,Zn四种元素的含量均低于陆生高等植物的平均含量。该测定结果为改善西部地区生态环境,选择优良防风固沙树种提供可靠的数据和理论依据。     

Gradient-elastic tensor in aluminium

The gradient-elastic tensor relating the electric field gradient tensor at the given nucleus to the elastic stress tensor was determined for aluminium to

$\text{C}{}_{11}\text{= 4·10}{}^3\text{dyn}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{and}\text{C}{}_{44}\text{= ?6.7·10}{}^3\text{dyn}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}$

The comparison of the measured values with the point charge approximation indicates a dominant effect of the conduction electrons on the electric field gradient.     

The separation of rhodium and iridium by anion-exchange

The separation of rhodium and iridium in amounts of 100–1000 μg was achieved with a strongly basic anion-exchange resin. Rhodium was eluted with 0.8 M hydrochloric acid containing cerium(IV) sulfate. Iridium was recovered by eluting with concentrated nitric acid at 74°C, which minimized the formation of hydrolysis products. Recoveries of 98% or more were obtained for both metals.     

抗阿尔兹海默症藏药三味豆蔻汤的化学成分分析研究

三味豆蔻汤作为藏药的经典方剂,由药材豆蔻、香旱芹、荜茇和牦牛奶熬煮制成,其对阿尔兹海默症(Alzheimer's disease,AD)具有一定的治疗作用.该方剂化学成分复杂且极性、挥发性差异大,相关的物质基础研究较少.该研究分别采用气相色谱-质谱(GC-MS)、超高效液相色谱-高分辨串联质谱(UPLC-HRMS/MS...