Hiroyuki Nariai

Bio: Hiroyuki Nariai is an academic researcher from Kobe University. The author has contributed to research in topics: Thermal decomposition & Phosphate. The author has an hindex of 17, co-authored 79 publications receiving 896 citations.

Formation and catalytic characterization of various rare earth phosphates

Abstract: Various rare earth phosphates [rare earth elements: R = La, Ce, Pr, Nd, Sm, Yb, and Y; phosphates: Monazite-type, Xenotime-type, Rhabdophane-type, and Weinshenkite-type orthophosphates RPO4, polyphosphate R(PO3)3, and ultraphosphate RP5O14] were synthesized by heating the mixtures of each rare earth oxide and diammonium hydrogenphosphate or phosphoric acid. The compositions of rare earth phosphates were determined by XRD, FT-IR, and TG–DTA. Catalytic properties were studied as one of properties of various rare earth phosphates. Specific surface areas of samples were measured by the BET method. Acid strengths and amounts of acidic sites were measured using several indicators by n-butylamine titration. Acidic properties were also confirmed by adsorption of ammonia. Various rare earth phosphates were characterized by catalytic activities on dehydration reaction of 2-propanol, cracking/dehydrogenation reaction of cumene, and isomerization reaction of butene. The characterization of catalysts was discussed with regard to type of rare earth elements, type of phosphates, and type of phosphorus resources.

Addition of rare earth cation on formation and properties of various cobalt phosphates

Abstract: Various cobalt phosphate pigments were prepared with the addition of rare earth cation by heating the mixtures of ammonium dihydrogenphosphate, cobalt carbonate, and rare earth (Y, La, and Nd) oxide. The thermal behavior of these mixtures was characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), and FT–IR analyses. The thermal products were estimated from scanning electron micrographs (SEM), particle size distribution, specific surface area, UV–vis reflectance spectra, and fluorescence spectra. Furthermore, the acid and base resistance of these materials was evaluated. The thermal reactions were clarified in these systems. Formation of cobalt–neodymium phosphate composite particles were considered from specific surface area. Cobalt pyrophosphate and cyclo -tetraphosphate had more vivid color hue than cobalt orthophosphate. These condensed phosphates had better acid and base resistance. By the addition of rare earth elements, the acidic and basic resistance of cobalt phosphates was remarkably improved.

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Abstract: Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Advanced Organic Chemistry

Abstract: Organic Chemistry By Dr. I. L. Finar. Vol. 2: Stereochemistry and the Chemistry of Natural Products. Pp. xi + 733. (London and New York: Longmans, Green and Co., Ltd., 1956.) 40s. net.

Prebiotic Chemistry and the Origin of the RNA World

Abstract: The demonstration that ribosomal peptide synthesis is a ribozyme-catalyzed reaction makes it almost certain that there was once an RNA World. The central problem for origin-of-life studies, therefore, is to understand how a protein-free RNA World became established on the primitive Earth. We first review the literature on the prebiotic synthesis of the nucleotides, the nonenzymatic synthesis and copying of polynucleotides, and the selection of ribozyme catalysts of a kind that might have facilitated polynucleotide replication. This leads to a brief outline of the Molecular Biologists' Dream, an optimistic scenario for the origin of the RNA World. In the second part of the review we point out the many unresolved problems presented by the Molecular Biologists' Dream. This in turn leads to a discussion of genetic systems simpler than RNA that might have “invented” RNA. Finally, we review studies of prebiotic membrane formation.

Systematic synthesis and characterization of single-crystal lanthanide orthophosphate nanowires.

Abstract: A simple hydrothermal method has been developed for the systematic synthesis of lanthanide orthophosphate crystals with different crystalline phases and morphologies. It has been shown that pure LnPO4 compounds change structure with decreasing Ln ionic radius: i.e., the orthophosphates from Ho to Lu as well as Y exist only in the tetragonal zircon (xenotime) structure, while the orthophosphates from La to Dy exist in the hexagonal structure under hydrothermal treatment. The obtained hexagonal structured lanthanide orthophosphate LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) products have a wirelike morphology. In contrast, tetragonal LnPO4 (Ln = Ho, Er, Tm, Yb, Lu, Y) samples prepared under the same experimental conditions consist of nanoparticles. The obtained hexagonal LnPO4 (Ln = La → Tb) can convert to the monoclinic monazite structured products, and their morphologies remained the same after calcination at 900 °C in air (Hexagonal DyPO4 is an exceptional case, it transformed to tetragonal DyPO...

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011.

Abstract: Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, rev ...