New phases with fluorite-derived structure in CaF2(Y,Ln)F3 systems

Crystallographic characteristics of six new phases of idealized composition Ca₈R₅F₃₁ which are formed in the CaF₂RF₃ (R = Y, HoLu) systems are reported. All the phases have a similar structure derived from CaF₂ with slight distortion and pseudocubic unit cell parameters a_ord = 13a_dis (where a_dis is the parameter of the fluorite subcell). The degree of ordering increases in the lanthanide series with decrease of ionic radius and, in every system given, with an increase in the RF₃ content of the solid solution. Significant influence of temperature and time of annealing on the degree of ordering was not detected.     

The structures of the α‐alums RbCr(SO4)2·12H2O and CsCr(SeO4)2·12H2O at 293 and 12 K

The crystal structures of the α‐alums rubidium chromium bis(­sulfate) dodecahydrate, RbCr(SO₄)₂·12H₂O, and caesium chromium bis[tetraoxoselenate(VI)] dodecahydrate, CsCr(SeO₄)₂·12H₂O, have been determined by X‐ray diffraction at 293 and 12 K. The metal atoms lie on sites and the anions lie on threefold rotation axes. The accurate and extensive data sets lead to much more precise determinations than are available from earlier work, particularly at 12 K. The changes in the atomic displacement parameters between 293 and 12 K correspond to the respective predominances of intermolecular and intramolecular vibrational effects.     

A semiempirical theory of a one-layer cellular sound-absorbing lining with a perforated face panel

On the basis of the known approximate theories and the recent experimental data, a semiempirical theory of a resonance-type one-layer cellular sound-absorbing lining is developed. Approximate formulas are obtained for calculating the effective normal impedance with allowance for the geometric parameters of the sound-absorbing lining, the high sound-pressure levels, the presence of an entraining flow, and the nonlinear interaction of sound components of different frequencies within a given one-third-octave spectrum of noise. The results of numerical calculations by approximate formulas are compared with experiments and with the experimental and theoretical data reported by other authors. The proposed theory is found to agree well with experimental data.     

Growth of Sm1 – ySryF3 – y (0 < y ≤ 0.31) Crystals and Investigation of Their Properties

Crystallography Reports - Sm1&nbsp;–&nbsp;ySryF3&nbsp;–&nbsp;y (0 &lt; y ≤ 0.31) crystals have been grown from melt by directional solidification in a...     

Growth of $${\text{N}}{{{\text{d}}}_{{{\text{1}}\; - \;y}}}{\text{Eu}}_{y}^{{{\text{2}} + }}{{{\text{F}}}_{{{\text{3}}\; - \;y}}}$$ Single Crystals with Tysonite-Type (LaF3) Structure and Investigation of the Concentration Dependence of Some Their Properties

Crystallography Reports - Nd1&nbsp;–&nbsp;yEuyF3&nbsp;–&nbsp;y crystals (y is the molar fraction of EuF2; 0 ≤ y ≤ 0.15) with a tysonite (LaF3) structure have...     

分光度法测定蒙药广枣中的微量铁

采用浓硝酸和高氯酸的混合消化法处理广枣样品,盐酸羟胺将铁(Ⅲ)还原成铁(Ⅱ),在pH为6的条件下,用分光度法测定铁含量,校准曲线回归方程为:y=0.00275779 0.18968x,(r=0.9999),回收率为99.5%-102.3%,RSD为0.72%,广枣中铁含量为66.5902μg/g.该方法操作简单,重现性好.