Catalytic generation of hydrogen by applying fluorinated-metal hydrides as catalysts

Metal–hydrogen complexes such as NaAlH₄, KBH₄, and NaBH₄ are known as high H-content materials. The highly reactive natures of these materials against moist air and water can be easily stabilized in aqueous KOH and NaOH solutions. Accordingly, it is required to develop catalysts suitable for generating hydrogen from the stabilized metal–hydrogen complexes in alkaline solutions. This work is aimed at developing catalysts that can generate hydrogen from such solutions with considerably high kinetics under moderate temperature and pressure conditions. We have found that Mg₂Ni, a typical high-temperature hydriding alloy, exhibits excellent functions as a catalyst for the hydrolysis of BH₄ ^--ion-containing solutions. The fluorination-treatment (F-treatment) effects on granular particles of Mg₂Ni and Mg₂NiH₄ are reported in this paper. Received: 13 November 2000 / Accepted: 14 November 2000 / Published online: 9 February 2001     

Dynamic light scattering from cylindrical bundle-like particles in suspension

The translational diffusion constants (D_t) of a single sarcomere have been obtained by a dynamic light scattering method (DLS) for both its rigor and its relaxing states. A similar experiment has also been performed for a single sarcomere modified into a more solvent impermeable intrastructure by a chemical decoration of adhering HMM particles (myosin head). It has been determined from the former experiments that there is hydrodynamically little structural difference between the rigor and the relaxing states, and from the latter experiments utilizing a modified sample, it has been found that there is a strong coupling between the D_t values and the compactness of the intrastructure. In this paper, we have made some hydrodynamical interpretations for the intrastructures of an I-Z-I and a single sarcomere. The results have also been supported by microscopial observations.     

Control of various morphological changes of poly(meth)acrylate microspheres and their swelling degrees by SPG emulsification

Crosslinked poly(meth)acrylate polymers with a variety of morphologies were synthesized with two steps. In the first step, a microporous glass membrane (Shirasu Porous Glass, SPG) was employed to prepare uniform emulsion droplets by applying an adequate pressure to the monomer phase, which was composed of the ADVN initiator, solvent of toluene or heptane or their mixture, and a mixture of (meth)acrylate monomers. The droplets were formed continuously through the membrane and suspended in the aqueous solution, which contained a PVA‐127 suspending agent, SLS emulsifier, and NaNO₂ inhibitor to suppress the nucleation of secondary particles. SPG pore sizes of 0.90, 5.25, and 9.25 μm were used. Then the emulsion droplets were polymerized at 343 K with a rotation rate 160 rpm for 24 h. The (meth)acrylate monomers 2‐ethylhexyl acrylate (2‐EHA), 2‐ethylhexyl methacrylate (2‐EHMA), cyclohexyl acrylate (CHA), methyl methacrylate (MMA), lauryl acrylate (LA), and lauryl methacrylate (LMA) were used in this research. The influences of the ratios of the monomer and crosslinking agent EGDMA, the amount of diluents, the monomer type on the polymer particle morphology, the swelling degree, and the polymer particle size were investigated. It was found that an increase in the concentrations of EGDMA and heptane resulted in higher coarse porous spheres and smaller polymer particle sizes. A coefficient with a variation close to 10%, or a standard deviation of about 4, was obtained. The capacity of these spheres as solvent absorption materials was examined. The highest swelling degrees of heptane and toluene were obtained when LA was employed as the monomer with 30% (by weight) of EGDMA and 70% (by weight) of heptane as an inert solvent. The highest capacity of the solvent absorption was obtained when using a polymer particle size of 4.81 μm, as prepared by SPG pore size 0.9 μm. The polymer particles were able to absorb aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and a mix of aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents, such as toluene and heptane. The capacity of solvent absorption for the aromatic hydrocarbon solvents was higher than for the aliphatic hydrocarbon solvents. In addition, the particles did not rupture or collapse after absorption in solvents. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4038–4056, 2000     

Formation of thermo‐sensitive and cross‐linkable micelles by self‐assembly of poly(pentafluorophenyl acrylate)‐containing block copolymer

Poly(pentafluorophenyl acrylate)‐block‐poly(N‐isopropylacrylamide) (PPFPA‐b‐PNIPAM) is synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization. Light‐responsive moieties of ortho‐nitrobenzyl (ONB)‐protected diamine are partially introduced to the PFPA moieties via postpolymerization modification. The amphiphilic block copolymers are assembled into micelles in water. The ONB‐protected diamine group in the micelle core is released upon UV irradiation, which subsequently induces an in situ cross‐linking by a spontaneous reaction with the remaining PFPA groups in the core and yields stable cross‐linked micelles. Micellization of the copolymers is confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). 4‐Nitro‐7‐piperazino‐2,1,3‐benzoxadiazole (NBD) and pyrene are loaded in the core of cross‐linked micelles to demonstrate the possibility for additional post‐functionalization of residual PFPA moieties and hydrophobic molecule encapsulation, respectively. It is anticipated that these micelles can be alternative cargos for incorporating active compounds that may be useful for advanced applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1103–1113     

Symmetric and Skew‐Symmetric ‐Matrices with Large Determinants

We show that the existence of ‐matrices having largest possible determinant is equivalent to the existence of certain tournament matrices. In particular, we prove a recent conjecture of Armario. We also show that large submatrices of conference matrices are determined by their spectrum.