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41.
Dr. Masaki Yoshida Dr. Mio Kondo Sena Torii Prof. Ken Sakai Prof. Shigeyuki Masaoka 《Angewandte Chemie (International ed. in English)》2015,54(27):7981-7984
Rational molecular design of catalytic systems capable of smooth O? O bond formation is critical to the development of efficient catalysts for water oxidation. A new ruthenium complex was developed, which bears pendant SO3? groups in the secondary coordination sphere: [Ru(terpy)(bpyms)(OH2)] (terpy=2,2′:6′,2′′‐terpyridine, bpyms=2,2′‐bipyridine‐5,5′‐bis(methanesulfonate)). Water oxidation driven by a Ce4+ oxidant is distinctly accelerated upon introduction of the pendant SO3? groups in comparisons to the parent catalyst, [Ru(terpy)(bpy)(OH2)]2+ (bpy=2,2′‐bipyridine). Spectroscopic, electrochemical, and crystallographic investigations concluded that the pendant SO3? groups promote the formation of an O? O bond via the secondary coordination sphere on the catalyst, whereas the influence of the pendant SO3? groups on the electronic structure of the [Ru(terpy)(bpy)(OH2)]2+ core is negligible. The results of this work indicate that modification of the secondary coordination sphere is a valuable strategy for the design of water oxidation catalysts. 相似文献
42.
This paper presents an alternative analytical method employing energy dispersive X-ray fluorescence (EDXRF) to determine copper, iron, nickel and zinc ions in ethanol fuel samples after a pre-concentration procedure. Our pre-concentration strategy utilizes analyte retention on cation exchange chromatography paper, a convenient substrate for direct EDXRF measurements. The repeatability, expressed in terms of RSD of standard solutions containing 0.25 μg mL−1 of Cu, Fe, Ni and Zn, and calculated from fifteen consecutive measurements, was 2.5, 2.8, 3.0, and 2.7%, respectively. The limits of detection (LOD), defined as the analyte concentration that gives a response equivalent to three times the standard deviation of the blank (n = 10), were found to be 13, 15, 15 and 12 μg L−1 for Cu, Fe, Ni and Zn, respectively. The proposed method was applied to Cu, Fe, Ni and Zn determination in hydrated ethanol fuel samples collected from different gas stations. 相似文献
43.
Functionalized aminophosphine of the type Ph2PNR2 ( 1,2 ) have been synthesized by treating Ph2PCl with N‐phenylpiperazine or N‐ethylpiperazine. Oxidation of these ligands with aqueous hydrogen peroxide, elemental sulfur or selenium afforded the corresponding phosphine oxides 3,4 , sulfides 5,6 , and selenides 7,8 in good yields. The molybdenum complexes of the aminophosphines have been obtained. All new compounds were fully characterized by IR, NMR, and microanalysis, and the molecular structures of two representative compounds were determined by single‐crystal X‐ray crystallography. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:679–686, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20733 相似文献
44.
Application of electron beam irradiation combined to conventional treatment to treat industrial effluents 总被引:2,自引:0,他引:2
C. L. Duarte M. H. O. Sampa P. R. Rela H. Oikawa E. H. Cherbakian H. C. Sena H. Abe V. Sciani 《Radiation Physics and Chemistry》2000,57(3-6):513-518
A preliminary study to combine electron beam irradiation process with biological treatment was carried out. Experiments were conducted using samples from a governmental wastewater treatment plant (WTP) that receives about 20% of industrial wastewater, with the objective of destroying the refractory organic pollutants and to obtain a better performance of this plant. Samples from five different steps of WTP were collected and irradiated in the electron beam accelerator in a batch system with 5.0, 10.0 and 20.0 kGy doses. The main results showed a removal of 99% of all organic compound analysed in the industrial receiver unit (IRU) effluent and in the coarse bar screen (CBS) effluent with a 20 kGy dose, and for the medium bar screen (MBS) and primary sedimentation (PS) effluent a 10 kGy dose was sufficient. In the case of final effluent (FE), a dose of 5 kGy removed the remaining organic compounds and dyes present after biological treatment. 相似文献
45.
A tight-binding model is used to study the energy band of graphene and graphene ribbon under simple shear strain. The ribbon consists of lines of carbon atoms in an armchair or zigzag orientation where a simple shear strain is applied in the x-direction keeping the atomic distances in the y-direction unchanged. Such modification in the lattice gives an energy band that differs in several aspects from the one without any shear and with pure shear. The changes in the spectrum depend on the line displacement of the ribbon, and also on the modified hopping parameter. It is also shown that this simple shear strain tunes the electronic properties of both graphene and graphene ribbon, opening and closing energy gaps for different displacements of the system. The modified density of states is also shown. 相似文献
46.
Patrícia Xavier Baliza Leonardo Sena Gomes Teixeira Valfredo Azevedo Lemos 《Microchemical Journal》2009,93(2):220-224
In this work, a procedure for preconcentration of cobalt using dispersive liquid–liquid microextraction (DLLME) with the reagent Br-TAO as complexing reagent was developed. The procedure is based on a ternary system of solvents, where appropriate amounts of the extraction solvent, disperser solvent and the chelating agent Br-TAO are directly injected into an aqueous solution containing Co(II). A cloudy mixture is formed and the ions are extracted in the fine droplets of the extraction solvent. After extraction, the phase separation is performed with a rapid centrifugation, and cobalt is determined in the enriched phase by FAAS. Under the optimized conditions, the detection limit obtained was 0.9 µg L− 1. The enrichment factor and the consumptive index were 16 and 0.31 mL, respectively. The accuracy of the method was tested by the determination of cobalt in certified reference material of spinach leaves, NIST 1570a. The proposed procedure was successfully applied to the determination of cobalt in water samples. 相似文献
47.
M. J. Tiera V. Ap. de Oliveira Tiera E. C. de Toledo G. L. de Sena 《Colloid and polymer science》2000,278(11):1052-1060
The behaviour of hydrophobically modified poly(allylammonium) chloride having octyl, decyl, dodecyl and hexadecyl side chains
has been studied in aqueous solution using fluorescence emission techniques. Micropolarity studies using the I
1/I
3 ratio of the vibronic bands of pyrene show that the formation of hydrophobic microdomains depends on both the length of the
side chain and the polymer concentration. The I
1/I
3 ratio of the polymers with low hydrophobe content (less than 5% mol) changes substantially when reaching a certain concentration.
These changes are assigned to aggregation originating from interchain interactions. This behaviour is also confirmed by the
behaviour of the monomer/excimer emission intensities of pyrenedodecanoic acid used as a probe. For polymers having dodecyl
side chains and hydrophobe contents higher than 10%, aggregates are formed independently of the polymer concentration. Anisotropy
measurements show that microdomains resulting from the inter- and/or intramolecular interactions are similar to those observed
for cationic surfactants. Viscosity measurements show that the coil dimensions are substantially decreased for the polymers
having high hydrophobe contents, indicating intramolecular associations.
Received: 10 November 1999/Accepted: 7 April 2000 相似文献
48.
Leonardo Sena Gomes Teixeira Antônio Celso Spínola Costa Júlio César Rosa Assis Sérgio Luis Costa Ferreira Mauro Korn 《Mikrochimica acta》2001,137(1-2):29-33
A new sensitive method exploiting solid-phase spectrophotometry is proposed for the determination of cobalt in pharmaceutical
preparations. The chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN) was immobilized on C18 bonded silica loaded into
a home-made cell with 1.5 mm of optical path for cobalt determination. Cobalt(II) reacts with TAN on C18 material, at pH 6.0–7.5,
to give a coloured complex which has maximum absorption at 572 nm. In this way, the sample was passed through the cell and
Co(II) ions were quantitatively retained on the solid-phase. After the direct measurement of light-absorption in the solid
phase, only the cobalt was eluted with 0.1 mol L−1 hydrochloric acid. The cell was washed with water and then another sample solution could be passed through the cell. The
procedure allowed the determination of cobalt in the range of 10–160 μg L−1 with coefficient of variation of 4.7% (n=10) and apparent molar absorptivity of 2.62 × 106 L mol−1 cm−1 using sample volume of 3-mL.
Received May 15, 2000. Revision August 28, 2000. 相似文献
49.
Gisseli Souza Valasques Ana Maria Pinto dos Santos Leonardo Sena Gomes Teixeira Uillian Mozart Ferreira da Mata Cerqueira Valdinei Santos de Souza 《应用光谱学评论》2017,52(8):729-753
Emulsified systems are characterized by an immiscible liquid dispersed in another liquid in the form of droplets. These systems can be classified according to the size of the dispersed droplets obtained in coarse emulsions (0.5–50 µm) or microemulsions (0.01–0.10 µm). These systems have several properties that make them interesting in several fields of technology, and the emulsion formed by oil droplets dispersed in an aqueous phase (O/A) is the most used in analytical determinations due to its low viscosity and organic load. This paper discusses the characteristics of emulsified systems, their obtention, stabilization, properties and use in the development of analytical methods for elemental analysis in matrices with high organic content such as oils, fatty foods and fuel matrices. 相似文献
50.
Prof. Dr. Azusa Kondoh Sena Takada Kohei Aita Prof. Dr. Masahiro Terada 《European journal of organic chemistry》2023,26(25):e202300425
A methodology for the formal addition of β-acylalkenyl anions was developed by utilizing the [1,2]-phospha-Brook rearrangement under Brønsted base catalysis. The two-step reaction involves the catalytic addition of α-oxygenated propargyl anions generated via [1,2]-phospha-Brook rearrangement to electron-deficient ketones and subsequent alcoholysis to afford tertiary alcohols having an enone moiety. This is a rare example of a catalytic carbon-carbon bond forming reaction of β-acylalkenyl anion equivalents, providing synthetic building blocks that are otherwise difficult to access. 相似文献