Quantitative analysis of methylguanidine and guanidine in physiologic fluids by high-performance liquid chromatography-fluorescence detection method.

A rapid and sensitive high-performance liquid chromatographic method has been developed for the quantitative analysis of methylguanidine and guanidine in physiological fluids. These quanidino compounds are separated on a 6 x 0.23 cm cation-exchange column with 0.5 M sodium hydroxide solution. The guanidino compounds are detected with a fluorometer, which monitors the fluorescent guanidine derivatives produced by the reaction of the eluted constituents with 9,10-phenanthrenequinone. Sensitivity to sub-nanomole levels of methylguanidine and guanidine is demonstrated. The method was successfully applied to physiological fluids such as serum and cerebrospinal fluid from uremic patients.     

Application of 28Mg to the kinetic study of Mg uptake by rice plants

The time course of Mg uptake and release using intact rice plants and ²⁸Mg as a tracer is presented. Since there is no conventional Mg tracer available, ²⁸Mg was produced via ²⁷Al(α, 3p)²⁸Mg reaction using a cyclotron. Using the purified ²⁸Mg tracer, it was found that the uptake amount of ²⁸Mg by the rice plants increased linearly during 30 min of application. After ²⁸Mg treatment for 90 min, the roots were sequentially washed with iced solution for 120 min. Within about 10 min, almost all of the ²⁸Mg, that was thought to be weakly bound to the apoplast, was washed away.     

Microwave spectroscopic study of the SiF radical

The microwave spectrum of the SiF radical was observed in both ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ of the ground vibronic state. The SiF radical was produced by a dc discharge either in a $\text{SiF}{}_4\text{SiH}{}_4$ mixture or in a transient molecule SiF₂ generated by the reaction of SiF₄ with heated solid silicon. The latter gave twice as intense a spectrum. A least-squares fit to the observed spectrum showed the rotational constant and the centrifugal distortion constant to be 17 350.2752(63) and 0.03188(13) MHz, respectively, with three standard errors in parentheses applying to the last digits of the constants. The lambda-doubling parameter p₀ was found to be negative, ?87.67 MHz, indicating that the ²Σ⁺ excited state contributions dominate over those of ²Σ^?. All four hyperfine coupling constants a, b, c, and d were determined and were employed to discuss the unpaired-electron spin and orbital distributions in the SiF radical.     

Reply to the note on the flow behaviour of combustion gas in the boundary layer of an MHD generator

The temperature profile in Fig. 3 of Ref. 1 is better approximated by a relation for a turbulent boundary layer than a laminar boundary layer. The critical Reynolds number is expected to be lowered in the flow train of MHD combustion gas because of large turbulence in the combustor and by roughness along the duct.