Generators of the frequency‐following response (FFR) were assessed in 13 guinea pigs by cooling of the whole body and by experimental lesions of the brain stem. In the temperature study, the amplitude‐temperature function of the FFR contained a significant cubic component that was absent from that of the cochlear microphonic potential (CM) recorded from the round window. The phase shift of the FFR increased with decreasing body temperature. In experimental lesions of the brain stem, a significant phase shift of the FFR was obtained following contralateral postcollicular section. The FFR amplitude with transection of the auditory nerve was similar to that found before surgical sections of the brain stem. The duration of the FFR after the transection corresponded precisely to that of the round window CM. These results indicate that the origin of the FFR contains both nonneural (ie, cochlea) and neural (ie, involving the inferior colliculus) generators.
The purpose of this study is to develop simple and efficient microwave digestion method for quantitative recovery of multi-elements from coal and coal derived products. Compared to the traditional digestion method in which the combined use of HCl, HNO{sub 3} and HF as well as a pretreatment before instrumental analysis to remove the organic residue are ordinarily required, the present method has become simplified by only use of HNO{sub 3} as digestion reagent and the pretreatment is possibly left out. Nineteen trace elements (Li, Be, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Hg, and Pb) in the solution was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and flow injection (FI) ICP-MS. The validation of the present method was assessed by using three standard coals and comparing to the determination results of more coals obtained by the standard analysis methods. Most trace elements in the coals were found to be recovered quantitatively. (Abstract only).
