Cu-loaded dealuminated Y zeolites active in selective catalytic reduction of nitric oxide with ammonia

The selective catalytic reduction of NO with ammonia in the presence of oxygen has been carried out on Cu-loaded dealuminated Y zeolite catalysts. Copper was introduced by the usual ion-exchange procedure with an aqueous solution of cupric acetate. On deeply dealuminated USY zeolites, Cu²⁺ was supported in the amount larger than 2Cu/Al=2, resulting in the formation of CuO fine particles in addition to the isolated and dimer Cu²⁺ species. The specific catalytic activity per surface copper on the CuO particles was very high compared with these Cu²⁺ species. NO adsorption measurement revealed the higher dispersion of CuO on the deeply dealuminated USY than on SiO₂, which made Cu/USY a better catalyst for the reduction of NO. The reaction intermediates were investigated through the IR spectra of adsorbed species.     

Photoresponsive peptide and polypeptide systems. VIII. Synthesis and reversible photochromism of azo aromatic poly(L-ornithine)

Poly(L -ornithine) having azo aromatic side chain was synthesized by the water-soluble carbodiimide procedure. The photochemical properties of the azo polypeptide poly[N^δ-p-(phenylazo)benzoyl-L -ornithine] (PPABLO) was investigated by absorption and circular dichroism spectroscopy in hexafluoro-2-propanol (HFIP). The photochromism of the dichroic bands in the visible and ultraviolet wavelength regions was found to be reversible as a function of irradiation time at different wavelengths due to the photostationary state (about 70% trans)–cis photoisomerization of the azo aromatic moieties. The reversible photoinduced solubility change was also studied. On irradiation PPABLO is soluble under ultraviolet light (cis) and precipitate under visible light (70% trans) in HFIP–water. A discussion was presented that includes results on azo aromatic poly(L -lysine).     

Synthesis and properties of novel polysulfone bearing exomethylene structure

A novel polysulfone bearing exomethylene structure in the main chain was obtained by oxidation of polysulfide prepared by radical ring-opening polymerization of an eight-membered cyclic allyl sulfide, although the corresponding sulfone monomer was not polymerized at all. The thermal behaviors and the crystalline characters of the polysulfone and polysulfide are compared.     

Studies on the chemical modification of monensin. II. Measurement of sodium ion permeability of monensylamino acids using sodium-23 nuclear magnetic resonance spectroscopy

A technique to assay Na+ ions in cells is presented. Intracellular and extracellular Na+ ions in a suspension of guinea pig erythrocytes were conveniently determined by using sodium-23 nuclear magnetic resonance (23Na-NMR), in combination with two anionic shift reagents: Dy(TTHA)3- and Dy(PPPi)2(7-). Monensin (1), monensylalanine (2b), monensylserine (2c), and monensylphenylalanine (2d) induced large increases of intracellular Na+ ion concentration ([Nain]), while monensylglycine (2a), monensyltyrosine (2e), monensylaspartic acid (2f), and monensylglutamic acid (2g) showed slight increases. The values of initial increasing rate (Vi) of 2a-g were much smaller than that of 1. This fact was probably due to the lower lipophilicity of 2a-g than 1, because a good correlation was observed between Vi and Rm50 values of 1 and 2a-g. This lower lipophilicity is a consequence of conformational differences between 1 and 2a-g.     

Macro-azo-initiators composed of various polyesters: Their syntheses,thermal properties,and application to block copolymerization

Various aliphatic polyesters such as poly (ethyleneadipate), poly (tetramethylene adipate), poly (caprolactone), and poly (carbonate) were condensed with 4,4'-azobis-4-cyanopentanoyl chloride to prepare macro-azo-initiators. Their thermal properties, observed by differential scanning calorimetry, showed similar decomposition behavior to each other. Block copolymers containing each of these polyesters as a block segment combined with polystyrene or poly (methylmethacrylate) have been derived by the polymerization of monomers initiated with these macro-azo-initiators. © 1994 John Wiley & Sons, Inc.     

Colloidal crystals of cationic spheres

Colloidal single crystals of cationic polymer spheres (198–250 nm in diameter) in deionized aqueous dispersions were formed for the first time. The spheres used were poly(styrene-co-methacryloyloxyphenyldimethylsulfonium) cations. These cations are unstable in deionized suspensions with mixed beds of cation-exchange and anion-exchange resins. This was clarified by reflection spectroscopy, pH, conductance and -potential measurements for 250 days after suspension preparation. Colloidal crystals formed over a period of 24 h for the deionized suspensions at sphere concentrations higher than 0.09 in volume fraction. The nearest-neighbor intersphere distances coincide satisfactorily with the calculated values using the diameter and the concentration of the spheres. Alloy crystals formed from binary mixtures of the cationic polymer spheres and the anionic silica spheres when the ratio of the volume fraction of cationic spheres against the sum of the both cationic and anionic spheres was smaller than 0.3.     

Oleanane acid from Myrica cerifera

From the twigs of Myrica cerifera L. (Myricaceae), a new oleanane triterpenic acid named myrica acid was isolated along with myricalactone and several other known constituents. The structure of the acid was determined as 3beta-hydroxy-1-oxoolean-11,13(18)-dien-28-oic acid on the basis of chemical and spectral evidence.