Phase transitions in U3O8−z: I, heat capacity measurements

The heat capacity of U₃O_8−z with various O/U ratios was measured in the range from 250 to 750 K, and λ-type heat capacity anomalies were found in each sample. The transition temperatures were 487 and 573 K for UO_2.663, 490 and 576 K for UO_2.656 and 508, 562 and 618 K for UO_2.640. The entropy changes of the transitions were 0.44 and 0.39 J K⁻¹mol⁻¹ for UO_2.663, 0.58 and 0.47 J K⁻¹mol⁻¹ for UO_2.656 and 0.62, 0.51 and 0.25 J K⁻¹mol⁻¹ for UO_2.640, increasing as O/U decreases. The enthalpy change due to the transition varied linearly with the transition temperature except for UO_2.640, showing the presence of the same mechanism of phase transition among the samples with various O/U ratios. The mechanism of the phase transition was discussed on the assumption that the transition is originated from the order-disorder rearrangement of U⁵⁺ and U⁶⁺ with a consequent displacement of atoms, similarly to the case of U₄O_9−y.     

Vaporization study on nonstoichiometric NbO2 ± x by mass-spectrometric method

The vapor pressures over nonstoichiometric NbO_{2 ± x}(s) (1.972?2.037) were measured by mass-spectrometric method in the temperature range 1958–2326 K. The congruently vaporizing composition in the NbO_{2 ± x} phase was determined to be stoichiometric NbO_2.000 from the composition dependence of the total vapor pressures. The partial pressures of oxygen were calculated as a function of temperature and O/Nb composition from the partial pressures of the gaseous species NbO₂(g) and NbO(g) over nonstoichiometric NbO_{2 ± x}, from which the partial molar enthalpies and entropies of oxygen were calculated as a function of O/Nb composition. The composition dependence of the partial molar enthalpy and entropy obtained suggested the existence of some kind of short-range ordering in the nonstoichiometric NbO_{2 ± x}(s) phase. The enthalpies of formation of nonstoichiometric NbO_{2 ± x}(s) were also determined as a function of composition by combining the partial molar enthalpies of oxygen with the enthalpy of formation of stoichiometric NbO_2.00(s). The phase diagram around NbO_{2 ± x} at high temperatures was determined from the vaporization study.     

Dietary supplement of isohumulones inhibits the formation of aberrant crypt foci with a concomitant decrease in prostaglandin E2 level in rat colon

Male Fischer 344 rats were subcutaneously injected with azoxymethane (AOM) twice weekly at a dose of 15 mg/kg and were fed with freeze-dried (FD) samples of beer brewed without hops (non-hops beer), beer with hops at 4 times the amount of regular lager beer (x 4-hops beer), and isomerized hop extract (IHE) for the whole experimental period (I/PI) or for the post-initiation period (PI) only. Feeding FD beer samples at a dose of 1% significantly decreased the number of aberrant cryp foci (ACF) in the PI protocol over five weeks.x4-hops beer showed stronger inhibitory effects on the development of the numbers of aberrant crypts per focus and large ACF with four or more crypts than non-hops beer. Feeding IHE to rats at a dose of 0.01% or 0.05% in either the I/PI or PI experiment significantly reduced the numbers of ACF. Prostaglandin E2 (PGE2) levels in colonic mucosa of AOM-treated rats were significantly reduced by feeding of IHE. PGE2 production induced by lipopolysaccharide/interferon-gamma (LPS/IFN-gamma) in RAW264.7 cells was also reduced by treatment with IHE and isohumulone in a dose-dependent manner. These observations suggest that isohumulones show chemopreventive effects on ACF formation in rat colon by inhibiting the production of PGE2.     

Deposition of chlorophyll-a Langmuir-Blodgett films onto an SnO2 optically transparent electrode

The deposition of chlorophyll-a monolayers onto an SnO₂ optically transparent electrode was studied in relation to the deposition ratio. The values of the deposition ratio, which were approximately 0.95 for the upward movement and very small but non-zero for the downward movement, suggest that the multilayers prepared are Z-type films containing a small fraction of the Y-type component corresponding to the non-zero value. This is consistent with the photo- electrochemical behaviour of the pigmented electrodes which is markedly dependent on the deposition ratios, indicating structural inhomogeneity or imperfection of the multilayers.     

An electrical conductivity and X-ray study of a high-temperature transition in U4O9

The high temperature transition in U₄O₉ has been studied by electrical conductivity measurements and X-ray diffraction. From the electrical conductivity measurements, a similar variation of log σ$\text{T}$ with reciprocal temperature to that in the transition range near room temperature is observed in the temperature range from about 300 to 800°C. Like the low temperature transition, a small lattice contraction is also observed in that temperature range by means of X-ray diffractometry, and the transition temperature increases from 530 to 620°C with increasing O/U ratio. After the transition the intensity of $\text{4a}{}_0$ superlattice reflections increases, but that of $\text{8a}{}_0$ superlattice reflections disappears. The mechanism of this high temperature transition is considered to be a second-order transition of the order—disorder type based on the configurational change of U⁴⁺ and U⁵⁺ with the shift of some portions of the lattice oxygen atoms from the lattice sites to the interstitial positions. The phase diagram of U₄O₉ is presented on the basis of the electrical conductivity and X-ray data.     

Disadvantages of muscle-sparing thoracotomy in patients with lung cancer

At our institute patients with lung cancer had traditionally undergone lobectomy with mediastinal lymph node dissection using a standard posterolateral approach. The considerable morbidity associated with the standard posterolateral thoracotomy led us to investigate an alternative muscle-sparing approach. A prospective, randomized study of 30 patients with primary lung cancer (stage I or II) was performed to compare the following: operative field size, number of dissected lymph nodes, surgery time, postoperative pain, shoulder range of motion, and pulmonary function test results between patients who underwent either standard thoracotomy (SP group, n = 15) or the muscle-sparing thoracotomy (MS group, n = 15). The procedure should provide enough operative field size to access to mediastinum. Compared with the standard posterior thoracotomy, the muscle-sparing thoracotomy supplied a smaller operative field (218 +/- 31 versus 165 +/- 41 cm2) and required more surgery time (87 +/- 13 minutes) than the standard posterior thoracotomy (66 +/- 12 minutes). There were no significant differences in the number of dissected mediastinal lymph nodes. During the early postoperative days, pain and restriction of shoulder flexion were significantly less in the MS group than in the SP group. There were no significant differences in pulmonary function between the two groups. In terms of the operative field there is a marked disadvantage with the muscle-sparing incision compared with standard thoracotomy. The operative field is significantly smaller than with a standard thoracotomy, requiring more time to dissect the mediastinum; however, the pain is less and shoulder range of motion is superior to what is seen after standard thoracotomy during the early postoperative period. We conclude that there is no overall advantage to using the muscle-sparing incision in patients with lung cancer.