ICP-AES法测定合金粉中的镍、铬、钴、铝和钇含量

采用ICP-AES法,直接测定合金粉中的Ni,Cr,Co,Al和稀土元素Y,优选了适宜的仪器测定参数和合适的分析谱线.研究了基体效应、共存元素间干扰及干扰校正方法,通过对实际样品的实验,测得Ni,Cr,Co,Al,Y检出限为10,10,8,10,3 μg·L-1;回收率96.5%,95.7,97.0%,97.9%,97.6%;RSD为1.06%,0.77%,0.70%,0.94%,0.50%.     

亚磷酸酯对新型冷冻机油抗磨性能的影响

本文合成了一系列短链、长链和大分子的亚磷酸酯，用Timken试验机和扫描电镜研究了它们对新型冷冻机油抗磨性能的改进作用。     

Parallel high-throughput accurate mass measurement using a nine-channel multiplexed electrospray liquid chromatography ultraviolet time-of-flight mass spectrometry system

A nine-channel multiplexed electrospray (MUX) liquid chromatography ultraviolet time-of-flight mass spectrometry (LC/UV/TOFMS) system has been used to simultaneously measure accurate masses of eluting components from eight parallel gradient LC columns. Accuracies better than 5 and 10 ppm were achieved for 50 and 80% of samples, respectively, from a single batch analysis of ten plates (960 samples) of a Fmoc-Asp(OtBu)-OH and reserpine mixture. Combinatorial library compounds were analyzed using this parallel high-throughput system in both positive and negative modes to rigorously verify expected products and identify side products. A mass accuracy of 10 ppm root mean square (RMS) is routinely obtained for combinatorial library samples from this high-throughput accurate mass LC/MS system followed by automated data processing. This mass accuracy is critical in revealing combinatorial synthesis problems that would be missed by unit mass measurement.     

Compression behavior of Zr<Subscript>41</Subscript>Ti<Subscript>14</Subscript>Cu<Subscript>12.5</Subscript>Ni<Subscript>10</Subscript>Be<Subscript>22.5</Subscript> bulk metallic glass up to 24 GPa

The compression of a Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.     

Morphologies of Fe-66.7 at.%Si alloy solidified in a drop tube

Because of their unusual optical, thermoelectric, and magnetic properties, iron sili- cides have attracted considerable attention in recent years. Among them, particular at- tention has been paid to the orthorhombic semiconducting iron disilicide β-FeSi2 due to its direct band gap of about 0.85 eV at room temperature, which makes it a candidate material to be used in optoelectronic devices in near-infrared light sources and detectors. In addition, β-FeSi2 has good physical and chemical sta…     

不插入探针检测耦合腔链各单腔频率的方法

介绍一种不需插入活塞探针进入耦合谐振腔链, 而由计算机通过微波网络分析仪, 从腔链的输入波导获取通带特性数据, 配以专门的软件, 便可分析求解各单腔频率的方法.     

A transition state wave packet study of the H+CH4 reaction

Transition state wave packet calculations have been carried out to obtain the thermal rate constants for the H+CH(4) reaction on the Jordan-Gilbert potential energy surface. The eight-dimensional model for the X+YCZ(3) type of reaction was employed by restricting the nonreacting CZ(3) group under a C(3V) symmetry. We calculated the cumulative reaction probability for the total angular momentum J=0, from which the thermal rate constants were obtained for the temperature range between 250 and 500 K by employing the J-K shifting approximation. It is found that the eight-dimensional rate constants agree very well with the seven dimensional ones, in which the CH bond length in the nonreacting CH(3) group is fixed, suggesting that the additional mode for the symmetry stretching in CH(3) group does not have any important effect on the reaction within the temperature range considered here. The present transition state wave packet results agree well with rate constants obtained from the previous seven dimensional initial state selected wave packet study, indicating the consistence of the treatments involved in these two studies. On the other hand, it is found that the energy threshold for the cumulative reaction probability for J=0 from the present study is higher than that from the full dimensional multiconfiguration time-dependent Hartree study by about 0.06 eV, resulting in severe discrepancy between the present rate constants and the multiconfiguration time-dependent Hartree results.     

联合宽带到达方向估计和语音特征增强的传声器阵处理方法

以提高室内混响环境下自动语音识别(ASR)性能为目标,讨论了一种小尺寸传声器阵处理方法.该方法采用基于旋转不变技术的信号参数估计算法(ESPRIT)计算宽带语音信号到达方向角,进行时延补偿;同时联合考虑阵列滤波与隐马尔可夫模型(HMM)识别过程,将识别输出结果反馈到前端的传声器阵处理,优化阵列滤波系数.与常规阵处理方法改善信号波形质量不同,本文通过调节阵列滤波系数降低待识别特征与训练模型之间的失配,直接提高识别过程中正确假设的概率.实验结果表明,上述方案能够有效降低会议室环境下孤立词有限词库ASR的错误概率,表现优于常规波束形成方法;采用全局优化进行阵列滤波设计,与局部优化算法相比,进一步改善了处理性能.     

A flexible functional module to regulate ultraviolet optical nonlinearity for achieving a balance between a second-harmonic generation response and birefringence

Rigid planar π-conjugated groups are adopted for designing ultraviolet (UV) nonlinear optical (NLO) materials extensively. However, for these UV NLO crystals, the realization of a strong second harmonic generation (SHG) response is commonly accompanied by undesired overlarge birefringence. Herein, we propose a new functional gene, the flexible π-conjugated (C₃H₂O₄)²⁻ group, for designing a UV NLO crystal with a balance between the SHG response and birefringence. Furthermore, the combination of low-coordinated and high-coordinated alkali cations with the flexible (C₃H₂O₄)²⁻ group results in finding a new mixed alkali malonate, KLi(C₃H₂O₄)·H₂O (KLMW). As expected, KLMW exhibits a strong SHG efficiency (3 × KDP) and moderate birefringence (0.103 @ 1064 nm). In addition, it has a short UV cut-off edge of 231 nm and can be conveniently grown from solution. More importantly, it realized fourth harmonic generation with type-I phase-matching. Therefore, these excellent properties make KLMW a potential practical UV NLO material.

The flexible (C₃H₂O₄)²⁻ groups were employed to design a new mixed alkali malonate KLi(C₃H₂O₄)·H₂O as an potential UV NLO crystal achieving the balance between strong SHG efficiency and moderate birefringence.