Functional monomers and polymers, 64. Synthesis of poly-β-alanine from β-alanine, β-alanyl-β-alanine,and β-alanyl-β-alanyl-β-alanine 4-dodecanoyl-2-nitrophenyl esters

Active 4-dodecanoyl-2-nitrophenyl esters of β-alanine, β-alanyl-β-alanine, and β-alanyl-β-alanyl-β-alanine were prepared, and tried to polymerize in various solvents. Nonpolar solvents were found to be convenient for the polycondensation reaction. The yield of the polycondensation was high for the monopeptide ester, and less for the dipeptide and tripeptide esters. The effect of temperature on the polycondensation reaction was also studied.     

Fibrous support for immobilization of enzymes

A poly(vinyl alcohol) (PVA) fiber support incorporating various aminoacetal functional groups has been developed for immobilizing enzymes. The aminated PVA fiber seems to adsorb enzymes with electrostatic force of attraction; thus the immobilization procedure is simple. By the use of this fiber having immobilized enzymes, the reaction between enzymes and substrates is nearly independent of the size of subtstrates. This newly developed type of fiber, which is formed by a mass superfine fibers (SFF), each measuring 1 μm or less in diameter, permits much more increased surface area than the conventional enzyme immobilization supports. Our studies of the properties of the fiber for immobilization of enzymes show the following results: (1) SFF has a greater ability for the immobilization of invertase than ordinary fibers; (2) dimethyl-aminated SFF has the best performance for the immobilization of invertase. From these results, it is concluded that the dimethyl-aminated SFF is an excellent support for the immobilization of invertase.     

Decomposition of chlorofluorocarbons on TiO2ZrO2

The decomposition of chlorofluorocarbons (CFCs) in the presence of water was examined over a variety of solid acid catalysts. The TiO₂ZrO₂ catalyst was found to have the highest activity and longest life among the catalysts examined. The activity of the TiO₂ZrO₂ catalysts depended upon the content of TiO₂. At the contents of TiO₂ from 58 to 90 mole%, the TiO₂ZrO₂ catalysts exhibited high activity, and these catalysts were proven to contain TiZrO₄ crystal. From the study of the XRD peak intensity of the TiZrO₄ crystal, it was highest on the TZ-58 which contained 58 mole% of TiO₂, and decreased with increasing the content of TiO₂. Furthermore, the conversion of CFC113 measured at 673 K was highest at TZ-58, and decreased gradually with increasing TiO₂ content. Therefore, the TiZrO₄ crystal influences the activity of decomposition of CFC113. However, the TiO₂ZrO₂ catalyst was gradually deactivated during the reaction due to the elimination of titanium atoms. A good relationship was found between the activity on TiO₂ZrO₂ catalyst and bond energy of CCl in the compounds of chlorofluorocarbons and hydrochlorocarbons, suggesting that the rate controlling step was the cleavage of CCl bond.     

Kinetic study on the first stage during thermal degradation of polystyrene

The kinetic parameters of the first stage of polystyrene degradation have been investigated to elucidate the reaction mechanisms using the flow reactor system. The decrease in molecular weight of polystyrene was recorded at minute intervals over the temperature range 310°–390°C. Generally, the first and second stages were observed by thermogravimetric analysis (t.g.a.), however in the early stage of the degradation volatile yields of at least 5% occurred. Therefore, using t.g.a. analysis it is difficult to detect this earlier stage. It became evident that the first stage in the earlier part of the reaction could be detected by g.p.c. analysis. We have observed the hidden kinetic parameters of the nature of the first stage of the polystyrene degradation. The results indicate that the main chains were degraded randomly with the small quantitative volatile groups in the first stage and the rates of decrease in molecular weight in the first stage against reaction temperatures were evaluated as log k_s = 12.0 ? 41300/RT.     

Microscopic structure of athabasca oil sand

A refined structural model for in situ oil sands is proposed in terms of the mutual arrangement of sand grains, fines, water and bitumen. In the Athabasca deposit, the sand grains consist mainly of quartz and their packing is such that the porosity is about 35%. In rich oil sand, 10–15% of the pore space is occupied by connate water whereas the remainder is occupied by bitumen. For lower grade oil sands, a direct correlation exists between the water content and the amount of fines (particles smaller than 44 μm) and an inverse correlation exists between the bitumen content and the amount of fines. These relationships are successfully explained in terms of the irreducible water saturation in a porous medium and the double layer interaction between sand and bitumen surfaces.     

Anodic Dissolution of Uranium Mononitride in Lithium Chloride-Potassium Chloride Eutectic Melt

Uranium-plutonium nitride is a candidate fuel for fast reactors, but its major drawback is ¹⁴C formation from natural nitrogen. One would probably have to use highly ¹⁵N-enriched nitrogen. A pyrochemical process with molten-salt electroreflning has been proposed as a means to increase the nuclear proliferation resistance of the fuel cycle. Molten-salt electroreflning could also be applied to nitride fuels to make possible the recycling of ¹⁵N. The anodic dissolution behavior of UN in LiCI-KCI melt was studied to provide the basis for a feasibility study of electroreflning of irradiated nitride fuels.     

Biocomposites Made from Short Abaca Fiber and Biodegradable Polyesters

Natural fiber‐reinforced biodegradable polyester composites were prepared from biodegradable polyesters and surface‐untreated or ‐treated abaca fibers (length ca. 5 mm) by melt mixing and subsequent injection molding. Poly(butylene succinate)(PBS), polyestercarbonate (PEC)/poly(lactic acid)(PLA) blend, and PLA were used as biodegradable polyesters. Esterifications using acetic anhydride and butyric anhydride, alkali treatment, and cyanoethylation were performed as surface treatments on the fiber. The flexural moduli of all the fiber‐reinforced composites increased with fiber content. The effect of the surface treatment on the flexural modulus of the fiber‐reinforced composites was not so pronounced. The flexural strength of PBS composites increased with fiber content, and esterification of the fiber by butyric anhydride gave the best result. For the PEC/PLA composites, flexural strength increased slightly with increased fiber content (0–20 wt.‐%) in the case of using untreated fiber, while it increased considerably in the case of using the fiber esterified by butyric anhydride. For the PLA composite, flexural strength did not increase with the fiber reinforcement. The result of soil‐burial tests showed that the composites using untreated fiber have a higher weight loss than both the neat resin and the composites made using acetylated fiber.

Flexural modulus of PBS composites as a function of fiber content.     

Guinea pig bone marrow cells treated with platelet-activating factor generate factor(s) which affects their DNA synthesis and microbicidal activity

We have previously reported that platelet-activating factor (PAF) induces proliferation and microbicidal activity of guinea pig bone marrow cells. In the present study, we have found that the conditioned medium of PAF- or nonmetabolizable PAF agonist-treated guinea pig bone marrow cells augmented DNA synthesis and induced microbicial activity of bone marrow cells. A PAF specific antagonist, CV-6209, inhibited generation of the active conditioned medium by PAF. Addition of the PAF antagonist only partially suppressed the augmentative effect of the active conditioned medium on DNA synthesis; this is consistent with the fact that, because of the rapid breakdown, no appreciable amount of PAF remained in the conditioned medium of PAF-treated cells. Although mouse bone marrow cells did not respond to PAF unlike guinea pig cells, their DNA synthesis was significantly enhanced by the conditioned medium of PAF-treated guinea pig bone marrow cells. Thus, some newly generated factor(s) distinct from the originally inoculated PAF seemed to modulate the bioactions of PAF on bone marrow cells. An appreciable amount of PAF was produced by calcium ionophore-treated guinea pig bone marrow cells. These findings indicate that PAF synthesized in guinea pig bone marrow cells induces generation in the cells of some factor(s) which affects proliferation or microbicidal activity. Presented at The Third International Conference on Platelet-Activating Factor and Structurally Related Ether Lipids, Tokyo, Japan, May 1989.     

Internal fracture of notched epoxy resins

The brittle fracture of round-notched epoxy resin bars subjected to plane strain bending has been studied at varying strain rates. Observations of fracture processes and surface morphologies revealed that the internal crack was nucleated at the plastic-elastic boundary when the plastic deformation zone at the notch root reached a certain size. A slip-line field theory allows calculation of the stress components at the plastic-elastic boundary from a knowledge of the location of the internal crack. An analysis of the data concluded that the triaxial stress level ahead of the plastic zone was raised by plastic constraints to an ideal fracture stress which is considerably larger than that of glassy thermoplastics.     

Synthesis of Ba2NaNb5O15 Powders and Thin Films Using Metal Alkoxides

Transparent and highly oriented Ba₂NaNb₅O₁₅ (BNN) thin films have been prepared by using metal alkoxides. A homogeneous precursor solution was prepared by the controlled reaction of NaOC₂H₅, Nb(OC₂H₅)₅, and barium metal. The BNN precursor included a molecular-level mixture of NaNb(OC₂H₅)₆ and Ba[Nb(OC₂H₅)₆]₂ in ethanol. The alkoxy-derived powder crystallized to a low-temperature phase, and then transformed to orthorhombic BNN (tungsten bronze) at 600°C. BNN precursor films on substrates crystallized to orthorhombic BNN at 800°C via the low-temperature phase. Highly (002) oriented BNN films of tungsten bronze structure were successfully prepared on MgO (100) substrates at 700°C by using BNN underlayer.