Search results for "BOX"
showing 10 items of 2676 documents
Speciation of organic matter in natural waters. Interaction of polyacrylates with the major cation components of seawater
2004
The speciation of some high molecular weight polycarboxylates was studied in different ionic media. Polyacrylates here investigated (W=2.0, 5.1 and 20.0 kDa) form weak species with alkali metal cations (K=102 mol l1, t=25 jC, I=0 mol l1) and quite stable complexes with alkaline earth metal cations (K>106 mol l1, t=25 jC, I=0 mol l1). Results are reported from experiments performed in a multicomponent electrolyte solution simulating the major composition of seawater (artificial seawater). Protonation constants in this medium are expressed as a polynomial function of S1/2 (S=salinity) and the sharp lowering with respect to values obtained in non-interacting aqueous tetraalkylammonium salts ca…
Copper Octacarboxyphthalocyanine Aggregation in Buffered Solutions
2008
Results of spectral UV-Vis absorption investigations on association of copper octa-carboxyphthalocyanine, CuPcOC, are reported. Influence of pH on association is discussed. In pH < 5.5 only ag gre gates are present. Monomer appears above pH = 5.5 and at pH Greater-than or equal to 6.2 only monomeric Pc forms exist. CuPcOC exhibits higher tendency to wards association in phosphate buffer solutions than in redistilled water. In pH 5.9–6.0 monomers, dimers and trimers coexist in equilibrium in 1.0×10–6 – 1.2×10–5 mol/dm3 concentration range at 25°C. The average assembling number n = 3 was determined for pH 5.6, 5.9 and 6.0 solutions. The spectrum of aggregate was calculated with two maxima at …
Dimerization of Copper Octacarboxyphthalocyanine in Aqueous Solutions
2005
Spectral absorption UV-Vis investigations on association of copper(II) octacarboxyphthalocyanine in aqueous solutions are reported. In 5.0x10-7-5.0x10-5 mol/dm3 concentration range monomers and dimers are mainly present. The calculated dimerization constant 106dm3/mol at 25°C and the hypsochromic spectral shift for the dimer 1164 cm-1 (688 nm_ 637 nm) indicate a stack-like association of molecules and suggestpi-pi interactions between Pc macrocycles in dimer and higher aggregates, in contrast to hydrogen bonding between carboxylic groups of adjacent Pc molecules.
Teaching master's degree students to read research literature
2017
The skill to read research literature critically belongs in every university graduate’s toolbox. I have attempted to teach this skill in a master’s degree level course in programming languages over 15 years using, at various times, simulated conferences, voluntary reading exercises, evidence-based practice training, and a flipped classroom with mandatory reading assignments. I discuss my experience and analyze preliminary qualitative data on the use of evidence-based practice and a flipped classroom for this purpose. I present no firm conclusions, but expect that future work (by me or others) will be able to use my experience as a baseline for better teaching of research literature reading.…
N-(Pyrazin-2-yl)adamantane-1-carboxamide
2016
Molecules of the title compound, C15H19N3O, are composed of an adamantine unit and a pyrazine ring connected to each other through an amide bond. The H—N—C=O moiety is close to planar [C—N—C—O and C—N—C—C torsion angles of 4.7 (2) and −173.8 (1)°, respectively]. The N3—C5 bond has partial double-bond character [1.370 (1) Å]. The geometries of the pyrazine ring and the adamantane substituent are normal and in good agreement with closely related structures. In the crystal, molecules are connected by N—H...O hydrogen bonds, forming zigzag chains in the [001] direction and are arranged in a herringbone fashion.
cis,cis,cis-(Acetato-k2O,O´)bis[1,2-bis- (diphenylphosphanyl)ethane-k2P,P´]- ruthenium(II) 0.75-trifluoromethanesulfonate 0.25-chloride
2013
In the title RuII carboxylate compound, [Ru(C₂H₃O₂)(C₂₆H₂₄P₂)₂](CF₃O₃S)₀.₇₅Cl₀.₂₅, the distorted tris-bidentate octahedral stereochemistry about the RuII atom in the complex cation comprises four P-atom donors from two 1,2-bis(diphenylphosphanyl)ethane ligands [Ru-P = 2.2881 (13)-2.3791 (13) Å] and two O-atom donors from the acetate ligand [Ru-O = 2.191 (3) and 2.202 (3) Å]. The disordered counter-anions are located on the same site in the structure in a 3:1 ratio, the expanded formula comprising four complex cations, three trifluoromethanesulfonate anions and one chloride anion, with two such formula units in the unit cell. peerReviewed
Crystal structure of cis-bis(μ-β-alanine-κ2 O:O′)bis[trichloridorhenium(III)](Re–Re) sesquihydrate
2015
A dirhenium(III) cis-dicarboxylate complex is reported, which is representative of a small class of zwitterionic ammoniacarboxylato complexes involving a quadruple metal–metal bond.
Crystal structure of di-μ-isobutyrato-κ(4) O:O'-bis-[cis-di-chlorido-(dimethyl sulfoxide-κS)rhenium(III)].
2015
A binuclear bis(carboxylato)dirhenium(III) complex is reported. The compound is a representative of a small class of alkylcarboxylate complexes involving a quadruple metal–metal bonds
Intramolecular 1,5-S...N σ-hole interaction in (E)-N′-(pyridin-4-ylmethylidene)thiophene-2-carbohydrazide
2020
The hydrazide-hydrazone forms inverse dimers via hydrogen bonding, but its conformation is defined by the presence of an intramolecular chalcogen bond. Electrostatic forces dominate in the crystal packing and give rise to a layered supramolecular structure.
N,1-Bis(4-ethoxyphenyl)-2,6-dimethyl-4-oxo-1,4-dihydropyridine-3-carboxamide
2018
Condensation of ethyl acetoacetate and phenetidine gives the title compound, C24H26N2O4. The planar ethoxyphenyl group attached to the pyridine ring is twisted about 77.96 (11)° out of the plane of the N-ethoxycarboxamidopyridine unit. The carboxamide unit forms a dihedral angle of about 28.1 (2)° with the pyridine ring.