A kinetic study on the reaction of dicumyl peroxide with some low-olefin rubbers

The viscosity lowering of toluene solutions of isobutylene-isoprene rubber, polyisobutylene, and ethylene-propylene rubber in the reaction with dicumyl peroxide was investigated. By using the kinetic equations for the reaction of rubber with peroxide which had been derived previously by KIRIYAMA et al. the results of the experiments are discussed.     

Bildungsmechanismen im Primärschlackegebiet des Hochofens

Neues Verfahren zur Herstellung von großen Wüstitkristallen. Erörterung der Reaktionen zwischen Wüstit und Kalk-Kieselsäure-Gemischen. Deutung des Bildungsmechanismus im Primärschlackegebiet durch Erläuterung des Aufbaus hohler Körper aus reduzierten Eisenoxiden in Eiszapfenformen.     

Development of the computerized dental cast form analyzing system--three dimensional diagnosis of dental arch form and the investigation of measuring condition

To analyze the functional and morphological harmonies of the tooth and dental arch, a computerized system to measure a dental cast and to detect the apex of dental cusps and angle points of incisors was developed. Detailed morphology in the measured dental cast could be displayed distinctively by computer graphics (CG) with a surface model. Accuracy in determining the position of the apex of the dental cusp was examined by increasing the measuring pitch from 50 microns to 400 microns, the error increased gradually with increased measuring pitch. Taking the measuring error, the time for measurement and the memory size for analysis into account, a measuring pitch of 200 microns was determined to be reasonable. Three-dimensional data measurements from the apex of the dental cusp in molar, and the mesial and distal angles in canine and incisor were fitted to a polynomial formula. In the present measured model, the 4th order polynomial formula was used for the dental arch, and the 2nd order polynomial formula was used for the anteroposterior and lateral occlusal curves. These formulae could be simultaneously superimposed on the surface model of the dental cast, and displayed using CG.     

Laparoscopy-assisted radical nephrectomy for renal cell carcinoma in patients on long-term hemodialysis: report of 2 patients

We successfully performed a laparoscopy-assisted radical nephrectomy for renal cell carcinoma in 2 patients on long-term hemodialysis. Both tumors were incidentally discovered on screening by abdominal CT scanning. There were no complications during the operation or in the postoperative period, and both patients resumed normal activities by the fifth postoperative day. A laparoscopic-assisted radical nephrectomy may be useful for the treatment of renal cell carcinoma in hemodialysis patients.     

Expression of costimulatory molecules, B7-1 and B7-2 on human gastric carcinoma

Costimulation of T cells via B7-1 and B7-2 molecules on a tumor has been shown to be important for eliciting cell-mediated antitumor immunity. We studied the surface expression of B7-1 and B7-2 in 24 cases of gastric carcinoma from the primary locus, 20 cases of metastatic carcinoma from malignant ascites, 20 cases of benign gastric mucosa and 7 gastric carcinoma cell lines by two-color flow cytometry with mAb CD80 and CD86. The B7-1 and B7-2 molecules were expressed by 6 cell lines, and 1 cell line showed the predominant expression of B7-2 but not B7-1. Almost all patients with primary gastric carcinoma and benign gastric mucosa showed high levels of expression of the B7-1 and B7-2, revealing approximately 40%-60% positive cells. However, the percentage of B7-1-positive cells of poorly differentiated primary carcinomas was significantly lower than that of well-differentiated carcinoma and normal mucosa (P < 0.01). Furthermore, all of the metastatic carcinoma cells revealed consistently very low or undetectable levels of expression of the B7-1 molecule, only 8% (mean) of cells being positive, despite showing higher levels of B7-2 expression. Thus, it seems likely that decreased or deleted expression of B7-1 correlates with the grade of tumor differentiation, tumor progression and metastasis. These results suggest that the B7-1 molecule on the gastric carcinoma bearing CD80+CD86+ is abrogated during tumor invasion and/or metastasis, and the tumor finally acquires the CD80-CD86+ phenotype. Consequently, inadequate B7-1 costimulation may contribute to the escape of tumors from destruction by the host's immune system.     

The role of polyvinyl alcohol in emulsion polymerization

Emulsion polymerization of styrene (St) and vinyl acetate (VAc) in the presence of conventional polyvinyl alcohol (PVA), PVA modified with a terminal alkyl group or PVA modified with a terminal thiol group (HS-PVA) was compared. Whereas stable PVAc latexes were obtained, a stable PSt latex was obtained only in the case of HS-PVA. From the adsorption isotherms of these PVAs on the surface of PVAc and PSt latex particles, as well as the grafting efficiencies of VAc and St onto HS-PVA in relation to the stability of the polymerization process, the role of PVA in the emulsion polymerization was discussed.     

Systemic air embolism in an extremely low birthweight infant treated with high-frequency oscillatory ventilation

BACKGROUND: The autopsy is an educational experience that helps students correlate clinical findings with basic science issues. Because of the sensitive nature of the autopsy, students' attitudes should be considered prior to its design and implementation. METHOD: In 1992-1993, all 147 second-year students at the Medical College of Ohio completed a 26-item Likert questionnaire about their attitudes toward the autopsy. After participating in an elective autopsy experience, 26 students completed the same questionnaire plus 18 additional questions about the environment and behavior of the pathologist. Pre- and post-autopsy responses were factor analyzed using principal-components analysis with a varimax rotation. Student's t-tests were used to compare (1) the pre-autopsy factor scores of the elective participants and the rest of the class and (2) the pre- and post-autopsy scores of the participants. RESULTS: Factor analysis of the attitude questions identified seven factors. Comparison of the pre- and post-autopsy scores of the elective participants revealed statistically significant positive increases on four factors; three factors remained positive or neutral. CONCLUSION: It was concluded that the autopsy elective had a positive influence on the student's attitudes. In addition, the pathologist's behavior and the environment in which the autopsy occurred influenced the students. Twenty-two (85%) of the students indicated the autopsy should be mandatory for all students.