Hydrogenation properties and crystal structures of Ti−Mn-V BCC solid solution alloys

We have proposed new hydrogen absorbing alloys of the ‘Laves phase related BCC solid solution alloy’, the hydrogen capacity of which reaches almost double that of conventional rare-earth based AB₅ alloys. We have reported the hydrogen absorbing properties of Ti−V−Mn, Ti−V−Cr and T−V−Mn−Cr alloys. It has been accepted that the crystal structural change of BCC hydrogen absorbing alloys is the same as that of V metal. The mono-hydride (H/M=1) of V metal has a BCT structure and the di-hydride (H/M=2) has an FCC structure. However, we recently found that the Ti−V−Mn alloy shows different behaviors in phase transformation with hydrogenation to V metal. We found three hydride phases with a BCC, a deformed FCC and an FCC structure in the Ti−V−Mn solid solution alloy-H₂ system. The deformed FCC hydride phase has not yet to our knowledge been reported. The lattice constant of the deformed FCC was 0.407 nm, one axis of which is reduced by about 4%. Its single-phase region appeared at a hydrogen content between 0.8 H/M and 1.0 H/M in absorption at 298 K. The lower plateau observed due to formation of the deformed FCC hydride phase gives an increase of effective hydrogen capacity by decreasing hydrogen remaining in the alloy in the desorption process. This article based on a presentation made in the symposium “The 2nd KIM-JIM Joint Symposium: Hydrogen Absorbing Materials”, held at Hanyang University, Seoul, Korea, October 27–28, 2000 under the auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

Hydrogenation of C14 Laves phase alloy: CaLi2

The CaLi₂ alloy which was prepared by the induction melting method has been successfully hydrogenated. The CaLi₂ alloy synthesized had a hexagonal C14-type Laves phase structure and absorbed 6.8–7.1 mass% hydrogen under the temperature range from 273 K to 393 K. The hydrogenated CaLi₂ which consisted of CaH₂ and LiH hydride phases did not desorb hydrogen under 10 kPa-H₂ at the same temperatures. The hydrogen absorption kinetics measured under 3.1 MPa-H₂ at room temperature showed that the hydrogen content reached to 6 mass% in 10 s. No obvious hydrogen desorption from the hydrogenated CaLi₂ was observed even after evacuation for 20 h at 623 K.     

Self‐Degradable Lipid‐Like Materials Based on “Hydrolysis accelerated by the intra‐Particle Enrichment of Reactant (HyPER)” for Messenger RNA Delivery

RNA‐based therapeutics is a promising approach for curing intractable diseases by manipulating various cellular functions. For eliciting RNA (i.e., mRNA and siRNA) functions successfully, the RNA in the extracellular space must be protected and it must be delivered to the cytoplasm. In this study, the development of a self‐degradable lipid‐like material that functions to accelerate the collapse of lipid nanoparticles (LNPs) and the release of RNA into cytoplasm is reported. The self‐degradability is based on a unique reaction “Hydrolysis accelerated by intra‐Particle Enrichment of Reactant (HyPER).” In this reaction, a disulfide bond and a phenyl ester are essential structural components: concentrated hydrophobic thiols that are produced by the cleavage of the disulfide bonds in the LNPs drive an intraparticle nucleophilic attack to the phenyl ester linker, which results in further degradation. An oleic acid‐scaffold lipid‐like material that mounts all of these units (ssPalmO‐Phe) shows superior transfection efficiency to nondegradable or conventional materials. The insertion of the aromatic ring is unexpectedly revealed to contribute to the enhancement of endosomal escape. Since the intracellular trafficking is a sequential process that includes cellular uptake, endosomal escape, the release of mRNA, and translation, the improvement in each process synergistically enhances the gene expression.     

Ternary copolymers of hemin,styrene, and 1-vinylimidazole or 1-vinyl-2-methylimidazole as cyanide ion exchanger

Ternary copolymers, involving hemin (H) (ferri-protoporphyrin IX chloride), styrene, and 1-vinylimidazole (VI) or 1-vinyl-2-methylimidazole (VMI) in the different proportions, were synthesized by radical copolymerization. All the copolymers obtained were insoluble in aqueous solvents. No dissolution of H from the copolymers was observed even when the extraction with 0.5N NaOH or HCl was allowed to continue for a total time of 50 days. To clarify the functional capabilities of the ternary copolymers as a cyanide ion exchanger, the adsorption of cyanide ion onto the copolymers was investigated at different pHs. The amount (A_cn) of the adsorbed cyanide ion was found to be dependent on the content of H residue in the copolymer, thus indicating that the adsorption site for the cyanide ion consists of ferri-protoporphyrin IX (FP). Another important feature is that A_cn increases in proportion to the VI or VMI content of the copolymer. This result was discussed in terms of the coordination structure of the FP and also of the coordination reaction of cyanide ion to the FP.     

New type drill with three major cutting edges

Drilling performance of a new type twist is described. The new type drill has three major cutting edges, three chisel edges and three flutes. This drill is an efficient means of making a hole with high accuracy and no reaming. Recently, some research on drill materials including surface coating, drill point geometry, cutting forces and tool life have been carried out in order to increase the cutting performance of drills. All the drills used in these experiments were ordinary drills with two major cutting edges. The authors calculated the point geometry of the new type drill, and also examined the cutting characteristics of the drill with respect to cutting forces, hole accuracy and tool vibration. The experimental results showed that the whirling vibration which frequently occurs in an ordinary drill with two major cutting edges disappears when the new type drill is used, and thereby rifling marks do not results on the hole surface. Consequently, a hole with high roundness and straightness is obtained.     

Effect of Silicon on the Steam Oxidation Resistance of a 9%Cr Heat Resistant Steel

The steam oxidation of 9Cr–0.5Mo–1.8W steels containing 0.06 to 0.49%Si was investigated at 500°, 550°, 600°, 650° and 700°C. The steam oxidation rate of the steel decreased with increasing silicon content. The effect of silicon was most remarkable at 700°C. At 500°, 550° and 600°C, the effect was almost the same, and was smaller than that at 700°C. At 700°C, the formation of a protective amorphous-SiO₂ film reduced the oxidation rate considerably. On the other hand, at 600°C or less, silicon dissolved in the Fe–Cr spinel lattice with no evidence of SiO₂. At 650°C, although amorphous SiO₂ was observed, as at 700°C, at the scale–metal interface, the effect of silicon was the least within the test-temperature range. Thus, 650°C was a peculiar temperature for the effect of silicon on the steam oxidation of 9%Cr steels. The relatively small effect of silicon at 650°C is attributed to the formation of metastable FeO.     

The damping capacity improvement of machine tool structures by balls packing

Efficient manufacturing is achieved by the damping capacity improvement of machine tool structure. The purpose of this study is to clarify the parameters influencing the damping capacity of machine tool structures packed with balls. In structures closely packed with balls, various damping characteristics appear in correspondence with the ball size and other conditions. The effect of ball size is the most significant factor in these structures. Excitation of structure is necessary for close packing, however, this process is troublesome. Excitation of structure is required to achieve an optimum packing ratio where the maximum damping capacity is obtained. For a 50% packing ratio, this excitation process is not necessary to obtain a stable damping capacity. Therefore, the effects of magnitude of impulse, packed ball material, and structure size on the damping capacity are investigated at a 50% packing ratio. Finally, actual machine tool structure models are constructed, and the effectiveness of the balls packing for the damping capacity improvement is investigated.     

Copolymers of haemin and vinyl monomers as cyanide ion exchangers: Modifications of the ion exchange properties by introduction of acrylamide residues

Ternary copolymers of haemin (H) and styrene (St) with acrylamide (AAm), copoly(H, St, AAm), and with 1-vinyl-2-pyrrolidone (VP), copoly(H, St, VP), were synthesized by radical copolymerization. It was found that the H content of the resulting copolymer generally agrees with that of the corresponding monomer feed. Moreover, the yield and reduced viscosity decrease in proportion to the feed concentration of the H monomer. Each copolymer prepared showed hydrophilic character compared with the copolymer of H and St. The adsorption of cyanide ion onto the copolymer was investigated at different pHs to clarify the functional capability as cyanide ion exchanger. The amount of cyanide ion adsorbed on 1 g dry polymer (A_cn in mg/g) was found to be dependent on the H content of the copolymer, thus indicating that the haem-iron is the adsorption site of the cyanide ion. From the curves of A_cn against the AAm or VP content of the copolymer and against pH for copoly (H, St, AAm) and copoly(H, St, VP), it was observed that the adsorptive capacity of the cyanide ion is increased by the introduction of the AAm residue. The same result was obtained for column experiments. These results were discussed in connection with the reaction of a cyanide ligand with the haem-iron site in the copolymer.     

Hydration of fly ash cement

It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO₂ generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.