Comments on the hole mass in silicon inversion layers

Published experimental data for hole masses m_c in silicon inversion layers on (110), (111) and (100) surfaces are critically discussed. New results are presented for the (100) orientation. It is shown that self-consistent calculations of m_c agree with those experimental data, which are compatible with cyclotron resonance results. It is demonstrated that a theoretical treatment by Falicov and Garcia, which predicts too large hole masses, is not tenable.     

Singly Diagonally Implicit Runge–Kutta Methods with an Explicit First Stage

The purpose of this paper is to construct methods for solving stiff ODEs, in particular singular perturbation problems. We consider embedded pairs of singly diagonally implicit Runge–Kutta methods with an explicit first stage (ESDIRKs). Stiffly accurate pairs of order 3/2, 4/3 and 5/4 are constructed.     

Multielemental trace analysis by proton induced X-ray fluorescence

Conclusion The facility described above is the first accelerator based PIXE system installed and practically employed in Czechoslovakia. From the brief account presented here one can see that this rather unsophisticated device may be employed for solution of many analytical problems of practical importance. The device in the present experimental setup makes it possible to detect the elements with the atomic numbers above 20 at the mass level of about 10^–8 g. The last value corresponds to a minimum detectable concentration of about 10^–5 g/g for thin samples. Relative accuracy and precision are below 10% for the determination of the elements in the concentrations well above the detection limit. The performance of the PIXE facility will be improved substantially in the near future.We wish to thank Dr. A. Mastalka for supplying us with some standards which were employed in this study. Mr. K. Staníek, Mr. V. Cílek and Mr. P. erný are acknowledged for their help in the course of the experiments. The authors are also greatly indebted to Dr. J. ervená for her help in the analysis of the measured spectra.     

High-performance liquid chromatographic determination of ambroxol in human plasma.

Ambroxol has been determined in biological fluids using a rapid and sensitive high-performance liquid chromatographic method. The samples prepared from plasma by liquid-liquid extraction were analysed on reversed-phase silica gel by competing-ion chromatography with ultraviolet detection. The method was applied to the determination of ambroxol levels in twelve healthy volunteers after oral administration of 90 mg of ambroxol in tablets of Mucosolvan and Ambrosan.     

The143Nd (n.∝)140Ce reaction with 2 keV neutrons

She¹⁴³Nd (n,) reaction was investigated with 2 keV neutrons obtaiaed from a scandium filter. The cross section of (32±6) × 10^–30 cm² for averaged-transitions from the states of¹⁴⁴Nd compound nucleus to the¹⁴⁰Ce ground state was obtained.