The elastic modulus of the crystalline regions in some oriented polymers was determined. An x‐ray diffractometer specially constructed for this purpose was used, and the lattice extension in the direction of the fiber axis was measured under application of a direct load. Usually a meridional reflection was used for the measurement of the lattice extension, but in the case where no strong meridional reflection exists a reflection from planes which are almost perpendicular to the fiber axis of the crystallites was used. The elastic modulus was calculated under the assumption of a simple series model. The values found are as follows: polyvinyl alcohol, 255 × 104 kg./cm.2; polyethylene, 240 × 104 kg./cm.2; polypropylene, 42 × 104 kg./cm.2; polyoxymethylene, 54 × 104 kg./cm.2; cellulose, 137 × 104 kg./cm.2; polyvinylidene chloride, 41.5 × 104 kg./cm.2.

No abstract

Elastic moduli of the crystalline regions in high polymers have been studied. Oriented specimens were used throughout. Lattice strains were measured by an x‐ray technique in the direction of the fiber axis as well as in that perpendicular to the fiber axis. The moduli for both directions were calculated on the basis of the assumption that the stress is homogeneous within a specimen held under a load. Remits obtained for various kinds of polymers were discussed in terms of the crystal structures of the polymers, pan icularly the skeleton conformation and the cross‐sectional bulkiness of the chain molecule in the crystal. It was shown that the moduli in the direction of the fiber axis are widely different depending upon the polymer. They vary from 240 × 104 kg./cm.2 for polyethylene to 4.1 × 104 kg./cm.2 for isotactic poly (vinyl tert‐butyl ether). In the direction perpendicular to the fiber axis, the moduli were shown to take values within a narrow range of magnitude, 3–9 × 104 kg./cm.2. Some of these moduli were compared with the calculated values reported by several authors. To find experimental support for the assumption of the homogeneous stress, measurements were made by using several oriented specimens of different fine textural structures. Inherent values of the lattice moduli were obtained, regardless of the specimens used, which gives a strong support for the assumption.

p16, cyclin D1 and retinoblastoma protein (pRB) regulate G₁ to S transition and are commonly targeted in various cancers. However, few studies have simultaneously examined all components of the p16/cyclin D1/pRB pathway (RB pathway) in hepatocellular carcinoma (HCC). To clarify the role of the disruption of the RB pathway in HCC, we analyzed p16, pRB and cyclin D1 in 47 HCCs. Inactivation of p16 was detected in 30 of 47 HCCs (64%) by Western blot analysis and significantly correlated with hypermethylation of the promoter of this gene. pRB expression was found to be absent in 13 of 47 HCCs (28%) by immunohistochemistry. We found that 38 of 47 HCCs (81%) contained at least one inactivation in either pRB or p16. Furthermore, there was a significant inverse correlation between p16 and pRB inactivation (p = 0.041). Overexpression of cyclin D1 was detected in 5 of 47 HCCs (11%) by immunohistochemistry. The cases with cyclin D1 overexpression exhibited an advanced clinicopathological appearance and also contained inactivation of pRB and/or p16. These findings suggest that inactivation of pRB and/or p16 is a major event in human hepatocarcinogenesis, while cyclin D1 overexpression may confer additional growth advantages to the tumor in addition to pRB and/or p16 inactivation in HCC.

Some experiments were carried out to prove the validity of the assumption of a simple series model for the calculation of the elastic modulus of crystalline regions in oriented linear polymers from X-ray determination of lattice extension. Various specimens such as filaments, fibers, and films were prepared' from polyethylene, polyvinyl alcohol, polypropylene, polyoxymethylenq and cellulose; stress-strain curves constructed under the assumption of a simple series model; and calculated values of modulus compared. In spite of the differences of microstructures of these specimens, nearly the same value for the lattice modulus was obtained for each polymer. A large difference of specimen moduli had no effect on the lattice modulus. Lattice moduli of dry and water-swollen polyvinyl alcohols or cellulose did not differ from each other. These results are a strong support for the above assumption. I Extensibility of various polymer molecules was also discussed. ZUSAMMENFASSUNG:Es wurde eine Reihe von Versuchen durchgefuhrt, um die Giiltigkeit der Annahme eines einfachen Reihen-Modells fur die Berechnung des Elastizitatsmoduls der kristallinen Bereiche in orientierten linearen Polymeren mit Hilfe der rontgenographischen Messungen der Gitterdehnung zu beweisen.Von verschiedenen Proben wie Faden, Fasern und Filmen von Polyithylen, Polyvinylalkohol, Polypropylen, Polyoxymethylen und Cellulose wurden die Kraft-Dehnungskurven unter der obigen Annahme konstruiert und die Werte des Moduls miteinander verglichen. Trotz des Unterschiedes zwischen den Mikrostrukturen dieser Proben erhielt man fast den gleichen Gittermodul bei jedem dieser Polymeren. Die g o -l3en Unterschiede zwichen den makroskopischen Moduln der Proben hatten keinen E i d d auf den Gittermodul. Die Gittermoduln von trockenem und mit Wasser gequollenem Polyvinylalkohol oder auch Cellulose unterschieden sich nicht voneinander. Diese Ergebnisse stellen eine starke Stutze fur die oben erwahnte Annahme dar.Ferner wird die Dehnungsfahigkeit der verschiedenen Polymer-Molekule diskutiert.