Papers by Keyword: Bound State

Abstract: The extraction of tea seed oil obtained from wild camellia seed using supercritical CO2 extraction has been investigated. The extraction was carried out under operation pressures of 20, 30, 35, 40 and 50 MPas at 45°C, with a supercritical fluid flow rate of 5mL•min-1. The collected extracts were analyzed and the relative compositions of the tea oil were determined by gas chromatography-mass spectrometry(GC-MS). The purpose of this work was to investigate the effect of operation pressure on the extraction yield, extraction time, and extract composition. The results from supercritical CO2 fluid extraction (SFE) showed that the extraction pressure positively related to the extraction yield and negatively and linearly related to the extraction time. Only 5 constituents were found in the extract under the pressure of 20 MPa. However, about 20 constituents in the extract were obtained under the pressure of 35 MPa, approximately the same as those under 50 MPa. The curve of the extraction pressure versus the extraction yield demonstrated that the extractable constituents of wide camellia seeds have two states: a free state and a bound state. In the bound state, extractable constituents can only be extracted under an extraction pressure above the threshold. Taking into consideration of the extraction yield, equipment, and operation, the appropriate pressure of the SFE is between 36.4 MPa and 40 MPa.

Abstract: The driving force on an ion in a metal due to an applied electric field, called the electromigration force, is built up out of two contributions, a wind force and a direct force. The wind force is due to the scattering of the current carrying electrons off the ion. The direct force works on the effective charge of the ion. In the present work we concentrate on the direct force on a migrating proton embedded in an electron gas. For this force a sign change is obtained as soon as a bound state is formed. In recent calculations hardly a sign change was seen, although a bound state was found in a self-consistent-potential for lower electron densities. Here we show that a supplementary term shows up, as soon as one accounts for the bound state explicitly. By this the problem has been solved regarding a possible lack of completeness of the published formalism. The results presented are based on square-well model potentials. By using different depths it is possible to show results for potentials without a bound state and accommodating one bound state.