陶明
,
熊伟
,
陈华
,
李贤均
催化学报
合成了(R,R)-1,2-二苯基乙二胺((R,R)-DPEN)、钌和三苯基膦的三元配合物RuCl2[P(C6H5)3]2-(R,R)-DPEN,并将其用于萘乙酮的不对称加氢反应.考察了碱/催化剂的摩尔比、反应温度和氢气压力等对催化活性和对映选择性的影响.结果表明,多种因素对反应的转化率和对映选择性均有影响.在萘乙酮:(CH3)3COK:催化剂摩尔比为50 000:450:1,氢气压力为4 MPa,反应温度为25℃的条件下,反应16 h时,萘乙酮生成α-萘乙醇的产率和对映选择性分别达到了100%和83%.
关键词:
钌膦配合物
,
手性二胺
,
萘乙酮
,
不对称催化加氢
,
α-萘乙醇
,
对映选择性
秦鹏
,
李萍
,
侯天宇
,
赵杰
,
李廷举
材料工程
doi:10.11868/j.issn.1001-4381.2016.11.015
基于对影响非线超声性检测因素的探讨，考察了应用非线性检测无损评价H R3C烟侧腐蚀的可行性。结果表明：脉冲激励串个数 n≤2df／c ，加汉宁窗有助于降低系统干扰，此外，样品表面粗糙度对非线性系数β产生显著的影响。随腐蚀时间的延长，非线性系数呈现阶段性的递增趋势。腐蚀初期（腐蚀时间在50h以内），非线性系数增幅不足20％；然而，腐蚀至150h ，非线性系数显著增加；相对于未腐蚀样品，腐蚀200h时的非线性系数增幅达260％。非线性系数的单调变化与腐蚀损伤的加剧相一致，因此，应用超声非线性无损评价 H R3C的烟侧腐蚀是可行的。
关键词:
非线性超声检测
,
非线性系数
,
烟侧腐蚀
杨敏
,
常海萍
,
毛军逵
工程热物理学报
本文实验研究了离心力场下细微封闭循环通道中,以H2O和氟利昂R12为热驱动介质的热驱动流动规律和换热特性,重点分析了热驱动换热技果随Ra数Ro数的变化规律以及冷却效果.实验结果表明:在热流密度和旋转速度相同的条件下,采用介质R12可以获得较高的半均换热系数,冷却效果也优于以H2O为介质的冷却效果.最后建立了两种介质条件下相应的准则关系式.
关键词:
热驱动
,
热驱动介质
,
细微通道
,
旋转
,
换热系数
刘欢
,
严凯
,
晏井利
,
薛烽
,
孙甲鹏
,
江静华
,
马爱斌
中国有色金属学报(英文版)
doi:10.1016/S1003-6326(17)60007-4
为了揭示14H相的形成机理，制备并研究了18R LPSO单相Mg?Y?Zn(简称S18)合金经773 K退火100 h的显微组织演变。结果表明：铸态S18合金主要由18R相组成(其体积分数高于93%)，并含有少量的W相和α-Mg相。退火时，S18合金中的18R相保持稳定，未转变成14H LPSO结构。然而，在α-Mg相内部形成了14H层片相，其尺寸和体积分数随着退火时间的延长不断增大。TEM分析表明，14H相在α-Mg内基面堆垛层错区域独立形核。14H层片的增厚生长是界面控制过程，与基面台阶的形成密切联系。而14H层片的伸长生长属于扩散控制，与溶质元素的扩散有关。该18R单相合金中14H相的形成机理可通过反应式α-Mg'→α-Mg +14H表示。
关键词:
Mg-Y-Zn合金
,
18R LPSO相
,
14H LPSO相
,
高温退火
,
显微组织演变
Communications in Theoretical Physics
The unified theoretical calculation of thermal shifts (TS) of R-1 and R-2 lines and thermal broadenings (TB) of R, R' and B lines for ruby was carried out for the first time. The calculated results are in very good agreement with a great number of experimental data. Especially by using quantum theory and taking into account all the admixtures of wavefunctions within d(3) electronic configuration, all the Gamma M in electron-phonon interaction (EPI), the electronic energy spectrum and lattice-vibration Spectrum, the very important contributions to TS and TB from single-phonon direct process were theoretically calculated in detail. The microscopic essentials of various contributions are revealed, and the mistakes in previous work are remedied.
关键词:
diamond anvil cell;pressure measurement;spectroscopy;temperatures
Journal of Applied Physics
Samples of R2Fe17C(y)N(x) (R = Y, Sm, Er, Tm) were prepared by arc melting appropriate amount of R, Fe, and C, vacuum annealing at 1373 K and finally annealing at 740 K in nitrogen for 10 h. The magnetic properties of these compounds were investigated by means of ac initial susceptibility, magnetization measurements, and x-ray diffraction. The thermal stability of the nitride phase was studied by differential scanning calorimetry. It was found that, when heated above 600 K, R2Fe17C(y)N(x) irreversibly decomposes N which is irrespective of the carbon concentration and rare-earth element. The Curie temperatures of R2Fe17C(y)N(x) are independent of the carbon concentration and are approximately 400 K higher than those of the corresponding pure R2Fe17 compounds. However, the Curie temperatures cannot be correlated to the composition x of the initial R2Fe17C(y)N(x) compounds at room temperature because some N was lost during the heating to T(c). In the Er and Tm compounds spin reorientation transitions were found, marking the change of the easy magnetization direction from the c axis to the basal plane with increasing temperature. The Tm compounds show an additional magnetic transition at low temperatures (below 40 K). A coexistence of the hexagonal and the rhombohedral structural modifications was found in Er2Fe17C(y)N(x) when y < 1.5, characterized by two different spin reorientation temperatures. The anisotropy fields of Sm2Fe17C(y)N(x) are higher than that of Sm2Fe17N(x). Indications of a magnetic phase transition were found also in Sm2Fe17C0.7N(x) and Sm2Fe17C0.9N(x).
关键词:
magnetocrystalline anisotropy;carbides;alloys
Journal of Magnetism and Magnetic Materials
The temperature dependence of the magnetocrystalline anisotropy field (mu-0H(a)) of R2Fe14B(1-y)C(y) and Nd2Fe12Co2B(1-y)C(y) (R = Nd, Pr; y = 0, 0.5) compounds has been determined by applying the SPD (singular point detection) technique in a high pulse magnetometer in the temperature range of 300-600 K. To determine the Curie temperature (T(c)) of the compounds, the ac initial susceptibility measurement was employed. It was found that the influences of carbon substituting for boron and cobalt substituting for iron on the Curie temperature are independent of each other and the latter has been understood as the case where all 2p electrons which transferred from carbon to 3d bands localize around Fe. The effect of crystal electric field acting on the rare earth site is dominant at temperatures below 400 K in R2Fe14B (R = Nd, Pr) compounds. The substitution of small amounts of cobalt for Fe does not affect the crystal electric field acting on the rare earth site very much.
关键词:
陈建新
,
胡芃
,
陈则韶
,
江斌
工程热物理学报
基于制冷剂物性计算软件NIST REFPROP 7.0及R125/R600a气液相平衡实验数据,使用MBWR状态方程结合Lemmon-Jacobsen混合物模型,对R125/R600a(50/50 mass%)混合替代工质的热力学性质进行了计算,并制作给出了其压焓图(p-h)、温熵图(T-s)和比定压热容图(c<,p>-T)及饱和性质表.最后理论计算分析了其空调制冷工况的性能,结果表明该混合工质具有与R22相当的压缩比和COP值,比R22较低的排气温度和较高的单位质量制冷量.
关键词:
热力学性质
,
R125/R600a
,
制冷替代工质
Journal of Magnetism and Magnetic Materials
The temperature dependence of the anisotropy field H(A) and the thermal expansion DELTA-l/l0 of R2Fe14X (R = Gd, Lu; X = B,C) were measured by applying the SPD technique for H(A)(T) and a membrane technique for DELTA-l(T)/l0. Comparing Lu2Fe14B and Lu2Fe14C the difference in the temperature dependence of H(A) is associated with the difference in the Invar-like thermal expansion between the two compounds.
关键词:
3d magnetism;anisotropy;gd2fe14b
Journal of Alloys and Compounds
The structure, Curie temperature and magnetostriction of R(Fe1-xAlx)(2) alloys (R = Dy0.65Tb0.25Pr0.1) (x less than or equal to 0.3) have been investigated. It was found that the matrix structure of R(Fe1-xAlx)(2) alloys is cubic Laves (Dy,Tb,Pr)(Fe,Al)(2). Its lattice parameter increases linearly, while the Curie temperature decreases, with increasing x. The second phase of PuNi3-type (Dy,Tb,Pr)(Fe,Al)(3) was found when x < 0.15. The magnetostriction of R(Fe1-xAlx)(2) alloys decreases with increasing x in high magnetic fields; however, it exhibits a peak at x = 0.05 in low magnetic fields (H less than or equal to 2 kOe).
关键词:
rare earth transition metal compounds;Laves phases;magnetostriction;dy0.9-xprxtb0.1fe2
