碳酸氢铵沉淀法制备氧化钇粉体时反应条件对产物粒度的影响

研究了碳酸氢铵沉淀法的反应条件对氧化钇粒度的影响,探讨了粒度变化规律。发现在沉淀反应中,晶型碳酸钇铵的形成与否是影响氧化钇粒度的关键因素。在较低的反应温度下,当碳酸氢铵和氯化钇的浓度大于0.25mol·L-1,摩尔比大于5,陈化时间大于60min时得到碳酸钇铵沉淀,经煅烧可获得粒度(D50)大于1μm的氧化钇。当反应物浓度较低、摩尔比小,陈化时间较短时得到无定型碳酸钇沉淀,煅烧沉淀可获得粒度(D50)小于0.5μm的氧化钇。实验证明选择适当的沉淀反应条件,可制备D50在0.3～10μm范围内的不同粒度级别的氧化钇粉体。     

活性炭分离-桑色素荧光法测定天然水中痕量铍

在溴化十四烷基吡啶存在下,铬天菁S与铍生成三元胶束络合物。在pH10.0氨～氯化铵缓冲介质中,活性炭定量吸附此络合物,用热盐酸洗脱铍,可与其他干扰离子分离,用桑色素荧光法进行测定。该法用于测定美国EPA标准水样和天然水中的痕量铍,结果令人满意。     

A nanocomposite consisting of plasma-polymerized propargylamine and graphene for use in DNA sensing

We report on a novel graphene-based nanoarchitecture modified with plasma-polymerized propargylamine (G-PpPG) and its application in electrochemical sensors for DNA. Films of G-PpPG were characterized by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The presence of graphene enhances the electrochemical activity of the films, and the high density of amino groups (deposited at a low plasma input power) on their surface assists in the immobilization of probe DNA on the water-swollen polymeric network. By contrast, the degree of hybridization of the total complementary target DNA to the probe DNA remains unchanged when G-PpPG nanofilms prepared at higher input power. No substantial non-specific adsorption of totally mismatched target DNA on the polymer films is observed because of the complete coverage of the probe DNA. The detection limit for total complementary target DNA is approximately 1.84 nmol?·?L^?1. The dynamic range extends from 0.1 to 1,000 nmol?·?L^?1. The new nanocomposite may also be used to immobilize other probe DNA sequences, and this makes the approach potentially applicable to the detection of other oligomers. Figure

Preparing the DNA sensor made from the graphene-based nanoarchitecture modified by using PpPG (G-PpPG) includes the following processes: (a) Modifying the Au electrode with the graphene nanosheet, (b) depositing the PpPG film onto the Au electrode coated with graphene, (c) immobilizing the probe DNA onto the G-PpPG film, and (d) hybridizing the MM0 target with the G-PpPG film immobilized with P1     

Motion of curves and surfaces in affine geometry

In this paper, motion of space curves by endowing an extra space variable in centro-affine geometry is discussed. It is shown that the 2 + 1-dimensional integrable shallow water wave equation arises from such motion. Motion of curves specified by acceleration field in centro-affine geometry is also investigated, some integrable system are found to be associated with the curve motion law.     

精密离心机大臂缩比样件热变形的测试

本文研究了整体构件热变形的高精度的测试方法并研制了相应的测试系统,测试分析了精密离心机关键部件碳纤维环氧树脂复合材料大臂缩小的模拟样件的热变形,为大臂实件的工艺参数设计和施工提供了基本依据,保证了这一关键构件具有极高的尺寸热稳定性.所研究的测试方法和测试系统亦具有推广应用的价值.     

碳青霉烯类抗生素亲水作用色谱方法研究及其应用

建立了测定人尿液和自来水中4种碳青霉烯类抗生素(比阿培南、美罗培南、多利培南和厄他培南)的亲水作用色谱方法,所用流动相具有较好的质谱兼容性,可用于色谱-质谱联用。以XAmide为色谱柱,考察了乙腈比例、缓冲盐浓度和pH值对4种抗生素保留的影响,提出了可能的保留机理;所发展的方法对目标样品具有良好的线性响应:比阿培南、多利培南和厄他培南的线性范围为0.1~250 mg/L, R²=0.9999;美罗培南的线性范围为0.5~250 mg/L, R²=0.9998; 4种抗生素的定量限(LOQ)为0.1~0.5 mg/L。尿液样品和自来水样品在5 mg/L和25 mg/L两个水平的加标回收率分别为100.4%~111.9%和79.6%~107.4%,相对标准偏差(RSD)分别不大于1%和5%。该方法准确、灵敏、简便,可用于人尿液和自来水中多种碳青霉烯类抗生素的检测。     

基于INtime的EtherCAT实时采集系统主站设计

为了满足EtherCAT网络通信的高实时性,提出了一种新的主站程序设计方案;基于Windows XP系统扩展INtime实时核的开发环境,使EtherCAT网络主站能够实现实时通信的要求;首先,介绍了EtherCAT网络的体系结构,然后,在分析INtime实时核扩展原理及EtheCAT网络通信原理的基础上,对主站功能模块进行了详细的划分,并给出了基于INtime实时系统的主站程序具体设计方法;最后,采用EtherCAT从站平台―高速多功能信号测试仪,验证了基于INtime的实时主站的功能,并对系统进行了测试分析,给出了实时性能测试的结果;实验结果表明设计的多功能采集系统主站具有高的实时性和可靠性特点。     

高效液相色谱-高锰酸钾氧化化学发光法测定水中的痕量苯二酚

基于酸性介质中甲酸对高锰酸钾-苯二酚氧化发光反应的增敏作用建立了高效液相色谱-化学发光柱后检测苯二酚的新方法。优化了高锰酸钾-苯二酚氧化发光反应及高效液相色谱分离苯二酚的条件,用甲醇-0.1 mmol/L β-环糊精水溶液(体积比为30∶70) 作为流动相可实现对水中3种苯二酚异构体的分离,且能与高锰酸钾-苯二酚氧化化学发光反应条件很好地偶合。对所测定的苯二酚异构体,方法的线性范围达两个数量级;以信噪比为3测得邻、间、对苯二酚的检出限(n=3)分别为:5.2,4.7,3.2 μg/L,对质量浓度均为0.10 mg/L的3种苯二酚混合溶液连续测定11次,邻、间、对苯二酚的相对标准偏差分别为2.8%,3.4%,6.5%。将该方法与固相萃取技术相结合,对河水中的痕量苯二酚进行了测定,加标回收率为92.1%~95.4%。     

微波加热制备含稀土(La2O3)矿渣微晶玻璃研究

利用矿渣制备微晶玻璃是提高矿产资源利用率的主要形式之一。本文以白云鄂博尾矿为原料,采用微波一步法制备了CaO-MgO-Al₂O₃-SiO₂(CMAS)系辉石相矿渣微晶玻璃。选择835 ℃作为晶化温度,研究了微波加热对微晶玻璃析晶行为和微观组织的影响。以La₂O₃作为研究变量探讨了La₂O₃添加对矿渣微晶玻璃析晶行为的作用。与传统的热处理制度相比,微波加热可以在较短的时间内达到较高的析晶效果。同时La₂O₃的添加促进了晶粒细化。由拉曼光谱分析,La离子添加会导致玻璃网络中桥氧的增多,促进了辉石相析晶。在La的添加量为4%(质量分数)时硬度最高,达到了829.22 MPa。     

Anisotropic Superconducting Properties of Kagome Metal CsV_3Sb_5

We systematically measure the superconducting(SC) and mixed state properties of high-quality CsV_3 Sb_5 single crystals with T_c～3.5 K.We find that the upper critical field H_(c2)(T) exhibits a large anisotropic ratio of H_(c2)~(ab)/H_(c2)~c～9 at zero temperature and fitting its temperature dependence requires a minimum two-band effective model.Moreover,the ratio of the lower critical field,H_(c1)~(ab)/H_(c1)~c,is also found to be larger than 1,which indicates that the in-plane energy dispersion is strongly renormalized near Fermi energy.Both H_(c1)(T) and SC diamagnetic signal are found to change little initially below T_c～3.5 K and then to increase abruptly upon cooling to a characteristic temperature of ～2.8 K.Furthermore,we identify a two-fold anisotropy of in-plane angular-dependent magnetoresistance in the mixed state.Interestingly,we find that,below the same characteristic T～2.8 K,the orientation of this two-fold anisotropy displays a peculiar twist by an angle of 60° characteristic of the Kagome geometry.Our results suggest an intriguing superconducting state emerging in the complex environment of Kagome lattice,which,at least,is partially driven by electron-electron correlation.