Enhanced coercivity of melt-spun Sm(Co,Fe,Cu,Zr)z ribbons annealed by improved process

The effects of conventional thermal annealing (CTA), rapid thermal annealing (RTA) and rapid recurrent thermal annealing (RRTA) on coercivity of the melt-spun Sm(Co_0.6Fe_0.27Cu_0.1Zr_0.03)_7.5 ribbons were systematically studied. The results show that the annealing parameters greatly affect the coercivity of the ribbons. The optimum coercivity is 9.8, 8.9 and 10.2 kOe for the CTA-treated, RTA-treated and RRTA-treated ribbons, respectively, indicating that the coercivity is not enhanced only by elevating the heating rate. Nevertheless, the coercivity increases to 15.1 kOe for the RRTA-treated ribbons when the cooling rate decreases to 1 °C/min.     

Beneficial effect of rapid recurrent thermal annealing on magnetic properties of SmCo-based films

The effects of conventional thermal annealing (CTA) and rapid recurrent thermal annealing (RRTA) on the magnetic properties of the SmCo-based films were investigated. The results show that the CTA-treated films exhibit amorphous structure with coercivity insensitively depending on annealing parameters as anticipated. As for the RRTA-treated films, single TbCu₇-type phase structure with well crystallization is observed. The coercivity of the RRTA-treated films is strongly correlated with annealing parameters, and its optimum value is larger than that of the CTA-treated films. It is suggested that the RRTA treatment has beneficial effects on the magnetic properties of the SmCo-based films.     

In situ investigation on rapid microstructure evolution in extreme complex environment by developing a new AFBP-TVM sparse tomography algorithm from original CS-XPCMT

A new sparse tomography method for observing the rapid internal microstructure evolution of material, called the Algebraic Filtered-Back-Projection and Total Variation Minimization (AFBP-TVM) iteration sparse reconstruction algorithm, was proposed in this paper. The new algorithm was developed by combining the two techniques of the Algebraic Reconstruction Technique (ART) and the Filtered-Back-Projection (FBP) on the basis of analysis in linear space. A series of numerical reconstruction experiments were conducted to validate the new algorithm. The results indicated the new algorithm can obtain satisfactory reconstruction images from 1/6 of the projections that were used in traditional algorithms. So the time spent on projection acquisition process can be reduced to 1/6 of that in traditional tomography method. The quality of images reconstructed by new algorithm was better than other algorithms, which was evaluated by three quantitative parameters. The normalized average absolute distance criterion and the normalized mean square criterion, which were used to evaluate the relative error of the reconstruction results (smaller value means better quality of reconstruction), decreased from 0.3758 to 0.1272 and from 0.1832 to 0.0894 respectively. The standardized covariance criterion, which was used to evaluate the similarity level (greater value means higher accuracy of reconstruction), increased from 92.72% to 99.30%. Finally, the new algorithm was validated under actual experimental conditions. The results indicated that the AFBP-TVM algorithm obtained better reconstruction quality than other algorithms. It meant that the AFBP-TVM algorithm may be a suitable method for in situ investigation on material's rapid internal microstructure evolution in extreme complex environment.     

液态金属Al快速凝固过程中团簇结构的形成特性

A simulation study on the formation characteristics of clusters in a large-scale liquid Al system consisting of 105 atoms has been performed by the molecular dynamics method. And a cluster-type index method（CTIM）has been used to describe the structural configurations of various clusters. The results demonstrate that the icosahedron clusters（12 0 12 0）and their combinations play the most important role in the microstructure transition. The nanoclusters（containing up to 104 atoms）have been formed by combining some middle clusters which have been formed by combining smaller basic clusters. The structures of these nano-clusters are very different from those of nano-clusters obtained by evaporation,ionic spray methods,and so on. The latter is formed by the multi-shell crystals accumulated with an atom as the center and the surrounding atoms arranged according to octahedron configuration. The center atoms of these basic clusters are bond-connected each other with the linear or twisting mode. The corners of the nano-cluster just could become the starting points of the dendrite growth in the solidification processes of liquid metals.     

石墨炉原子吸收法快速测定工业生产芳腈催化剂废水中钒的含量

基于含钒氧化物催化剂催化芳烃氨氧化反应制备芳腈化合物在工业上已经得到了应用,其中催化剂中活性组分钒含量流失进入产生的废水中是影响该反应性能的重要因素之一。本文应用石墨炉原子吸收法（GFAAS）直接测定废水中钒含量,通过对样品预处理中酸介质、酸浓度和石墨炉升温程序中关键影响因素进行考察,实验表明采用0.2%硝酸加热消解,灰化和原子化温度分别采用500℃和1500℃时,效果良好。方法检出限为0.21 μg/L,平行9次测试结果的相对标准偏差为2.5%,加标回收率为105.6% ~ 108.7%,准确度好、精密度高,废水经简单的加热消解可直接进样分析,具有简便、操作快捷等优点。该方法通过准确快速检测芳腈生产过程中产生的废水中钒的含量能够有助于评估工业装置在生产运行过程中的状态。     

基于LIBS的GdFe合金材料快速检测技术研究

为了明晰LIBS（激光诱导击穿光谱）技术检测稀土合金材料的光谱特点,进一步开发基于LIBS的快速检测方法,推动LIBS技术在稀土领域的应用。本文利用激光诱导击穿光谱仪对GdFe合金材料的激发光谱,结合信号强度及背景噪音,研究确定了最佳设置参数。分别考察激光器和光谱仪的参数设置对光谱的影响,根据激发光谱中相关谱线的变化趋势,探讨GdFe合金材料的LIBS检测方法。实验发现,GdFe合金样品与激光孔(Laser aperture)的距离(Z值)、激光能量和积分时间是影响 LIBS光谱信号强度和背景噪音的关键参数。因金属和合金样品表面常覆盖氧化层,考察了脉冲激光的预剥蚀次数对光谱稳定性的影响,研究得出,在双脉冲均为164 mJ激光能量的激发下,预剥蚀1次可保证光谱效果。同时研究了两个激光器同时激发和延迟激发对GdFe合金光谱成因的影响,发现单脉冲激发与双脉冲同时激发所得光谱的信号强度并非两束脉冲单独激发的累加信号。通过光谱分析,确定了Z值0.8 mm、两个激光器的脉冲能量164 mJ、积分时间12 μs、脉冲延时时间0 μs,GdFe合金材料的光谱效果最佳,可为GdFe合金材料的LIBS检测方法建立提供参考,拓展LIBS技术在稀土领域的应用,为稀土合金产品的快速检测技术发展提供基础研究数据。     

Regularization of the Burnett equations for rapid granular flows via relaxation

In [J. Fluid Mech. 361 (1998) 41] Sela and Goldhirsch have used the Chapman–Enskog expansion to derive constitutive relations for the pressure deviator P, heat flux q, and rate of energy loss Γ for rapid flows of smooth inelastic spheres. Unfortunately as in the classical Chapman–Enskog expansion for elastic spheres any truncation of the expansion beyond Navier–Stokes order (n=1) will possess unphysical instabilities. In this paper we propose a visco-elastic relaxation approximation that eliminates the instability paradox for all wave numbers, and provide a system of local equations allowing robust numerical approximations of gas dynamics valid to the Burnett order. This system is weakly parabolic, has a linearly hyperbolic convection part, and is endowed with a generalized entropy inequality in the case of purely elastic collisions, thus it is linearly stable for all wave numbers. It agrees with the solution of the Boltzmann equation up to the Burnett order via the Chapman–Enskog expansion.     

快速高分离度液相色谱-质谱联用方法筛选Tau蛋白激酶2抑制剂

建立了测定Tau 蛋白激酶2(Tau protein kinase 2, TPK2)催化反应产物磷酸化十肽(PKpTPKKAKKL)的快速高分离度液相色谱-质谱方法(RRLC/MS)用于筛选TPK2抑制剂. 反应溶液总体积为50 μL, 将终浓度为20 nmol/L的TPK2与终浓度为5 μmol/L的底物十肽(PKTPKKAKKL)于30 ℃反应30 min, 用等体积乙腈终止反应并加入终浓度为1 μmol/L的磷酸化十肽(PKpTPKKAKKV)作为内标, 采用Agilent SB-C₁₈色谱柱, 以乙腈-水为流动相梯度洗脱分离后, 用RRLC/MS进行定性及定量分析. 该方法可通过精确定量一定时间内的酶促反应产物来反映酶活性被抑制的程度, 作为TPK2抑制剂的筛选方法, 本方法具有简单、 灵敏、 快速的优点, 能够避免光谱法筛选可能产生的假阳性结果, 可用于TPK2的先导化合物的高通量筛选.     

近红外漫反射光谱技术快速预测蒸汽压片玉米常规成分含量的研究

应用近红外漫反射光谱分析技术(NIDRS),采用偏最小二乘法,建立了蒸汽压片玉米4个常规成分的近红外定量预测校正模型。研究中选用62个品种玉米的蒸汽压片为样本,光谱扫描范围为950～1650nm,采用中心化+导数+多元散射校正的预处理方法。研究得出粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和粗脂肪(EE)的校正模型交叉验证决定系数(R2VAL)分别为0.9511,0.9032,0.7143,0.9082,交叉验证误差(SECV)分别为1.53,1.89,2.45,0.50。本研究建立的模型可以用来准确、快速地预测蒸汽压片玉米的CP,NDF和EE的含量,为蒸汽压片饲料工业提供了一种快速、经济和绿色的质量检测技术。     

Rapid Determination of Guanidine Nitrate by Single - point Titration

报道了以S－十二烷基双硫腙－苦味酸为载体制备苦味酸根离子电极,研究了电极的性能,并以该电极为指示电极研究了硝酸胍的单点滴定分析,导出了定量关系式。以0.1000mol/L标准硝酸胍溶液滴定0.1000mol/L苦味酸,控制滴定至95％,10次实验的平均值为0.1002mol/L,相对标准偏差为0.24％,滴定至90％～95％相对标准偏差小于0.3％。用该法进行工业硝酸胍含量分析,数分钟就能完成,结果与重量法很好吻合。