Microwave Heating of Water, Ice and Saline Solution: Molecular Dynamics Study

In order to study the heating process of water by the microwaves of 2.5-20GHz frequencies, we have performed molecular dynamics simulations by adopting a non-polarized water model that have fixed point charges on rigid-body molecules. All runs are started from the equilibrated states derived from the I$_{c}$ ice with given density and temperature. In the presence of microwaves, the molecules of liquid water exhibit rotational motion whose average phase is delayed from the microwave electric field. Microwave energy is transferred to the kinetic and inter-molecular energies of water, where one third of the absorbed microwave energy is stored as the latter energy. The water in ice phase is scarcely heated by microwaves because of the tight hydrogen-bonded network of water molecules. Addition of small amount of salt to pure water substantially increases the heating rate because of the weakening by defects in the water network due to sloshing large-size negative ions.Comment: 21 pages, 13 figure

Microwave heating and collapse of methane hydrate by molecular dynamics simulations

Microwave heating of methane hydrate is investigated with electrostatic molecular dynamics simulations. The structure I of methane hydrate is constructed. When the methane hydrate with a density of 0.91 $\rm{g/cm}^3$ and temperature of 273 K is exposed to microwave electric fields, it suddenly collapses in liquid after a certain period of irradiation. However, a hydrate with a five percent higher density of 0.95 $\rm{g/cm}^3$ and the same initial temperature shows no collapse as a crystal caused by the microwave. A hydrate with CO$_{2}$ guest molecules has increased kinetic energy but rapidly collapses due to the Lennard-Jones potentials. The methane hydrate with variable density and temperature is presented and exhibits slow heating as a crystal and an unchanging volume.Comment: 16 pages, 2 tables, 8 figure

Characterization and hydrodesulfurization activity of CoMo catalysts supported on sol-gel prepared Al2O3

A series of CoMo/Al2O3 catalysts was prepared by impregnation on a series of alumina powders synthesized by the sol-gel method with different hydrolysis ratios R (defined as [H2O] / [aluminum-tri-sec-butoxide (ASB)]; R = 3, 4, ..., 12, 13). The oxide precursors were characterized and subsequently tested in the hydrodesulfurization (HDS) of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Mainly due to their large pore diameters of ca. 6 nm, the catalysts prepared from the alumina with hydrolysis ratio R = 7 ~ 10 showed higher HDS activity compared with the activities of the other prepared catalysts. The effect of the pore diffusional limitation was more significant than expected, due to the ink-bottle shape of the pores of the prepared catalysts with hydrolysis ratio R 10. Due to highly dispersed CoMo active phase, the HDS activity of the prepared catalysts with hydrolysis ratio R = 8 and 9 for thiophene was similar to that of a reference industrial catalyst that was designed and manufactured for deep HDS of diesel fuel fractions. Furthermore, the HDS activity of the prepared catalysts with hydrolysis ratio R > 5 for DBT was higher than that of the reference industrial catalyst. For 4,6-DMDBT, however, the reference industrial catalyst showed higher HDS activity compared with the activities of the prepared catalysts. Relatively high HDS activity was observed for the prepared catalysts with R = 9 and 10 with cylindrical pore shape and with a high proportion of strong acid sites. The strong acidity supposedly enhanced the hydrogenation activity of the catalysts that was essential for the HDS of 4,6-DMDBT

Prognostic assessment of 1310 patients with non–small-cell lung cancer who underwent complete resection from 1980 to 1993

AbstractObjective: The TNM staging system of lung cancer is widely used as a guide for estimating prognosis and selecting treatment modality. In 1997, the International Union Against Cancer and the American Joint Committee on Cancer have adopted a revised stage grouping for lung cancer. However, the validity of the new stage grouping has not been fully established. We investigated the prognoses of patients who had resection of non–small-cell lung cancer to confirm the validity of the revised classification. Methods: A total of 1310 patients with non–small-cell lung cancer underwent complete resection and pathologic staging of the disease in our hospitals from 1980 through 1993. A pulmonary resection was performed with a systematic nodal dissection. The survivals were calculated with the Kaplan-Meier method on the basis of overall deaths, and the survival curves were compared by log rank test. Results: There were significant differences in survival between patients with T1 N0 M0 and T2 N0 M0 disease and between those with T1 N1 M0 and T2 N1 M0 disease. However, there was no significant difference between patients with T2 N0 M0 disease and those with T1 N1 M0 disease. No significant difference in survival was observed among patients with T2 N1 M0, T3 N0 M0, and T3 N1 M0 cancer. Patients with different invaded organs of T3 subdivision (pleura, chest wall, pericardium, or diaphragm) had a different prognosis. There was no significant difference between patients with T3 N2 M0 disease and those with stage IIIB disease. Conclusions: We supported most of the revision, such as dividing stage I, dividing stage II, and putting T3 N0 M0 to stage IIB. Furthermore, we found some candidates for a subsequent revision, such as putting T3 N1 M0 to stage IIB, putting T2 N0 M0 and T1 N1 M0 together, regarding diaphragm invasion as T4, and putting T3 N2 M0 to stage IIIB. (J Thorac Cardiovasc Surg 1998;116:407-11