Search results for "Visible"

Comparative Study on the Determination of Cephalexin in its Dosage Forms by Spectrophotometry and HPLC with UV-vis Detection

1997

This paper discusses the spectrophotometric determination of cephalexin as the intact cephalexin or as its acid-induced degradation product. Cephalexin can be determined in the range 1 × 10−5−18 × 10−5M with relative standard deviations of 5-1%. The limits of quantitation and detection were 10−5 and 0.3 × 10−5M, respectively. These procedures were compared with reversed-phase HPLC determination. No interference was observed in the presence of common pharmaceutical adjuvants. The H-point standard additions method was applied in order to correct for the possible presence of the cephalexin precursor, 7-aminocephalosporanic acid; this improves the selectivity of the UV-vis spectrophotometric me…

A new selective fluorogenic probe for trivalent cations.

2012

[EN] A new selective chromo-fluorogenic probe for Fe 3+, Cr 3+ and Al 3+ is reported. Detection limits are in the ¿M range and the fluorogenic sensing ability could be observed by the naked eye when illuminated with UV-light. No response is observed with divalent cations. © 2012 The Royal Society of Chemistry.

Chiral self-sorting behaviour of [2.2]paracyclophane-based bis(pyridine) ligands

2019

Two constitutionally isomeric chiral bis(pyridine) ligands based on planar chiral 4,15-difunctionalized [2.2]paracyclophanes were synthesized, the respective enantiomers were separated via HPLC on a chiral stationary phase, and their self-assembly behaviour upon coordination to palladium(ii) ions was studied with regard to chiral self-sorting effects. As proven by NMR spectroscopy, mass spectrometry, CD spectroscopy, UV-Vis spectroscopy and X-ray crystallography both ligands form the expected dinuclear complexes upon coordination to cis-protected di- or tetravalent palladium(ii) ions, respectively, however, with distinct differences concerning their chiral self-sorting ability. peerReviewed

Multi-technique approach for qualitative and quantitative characterization of furazidin degradation kinetics under alkaline conditions

2016

Degradation of drug furazidin was studied under different conditions of environmental pH (11-13) and temperature (30-60°C). The novel approach of hybrid hard- and soft-multivariate curve resolution-alternating least squares (HS-MCR-ALS) method was applied to UV-vis spectral data to determine a valid kinetic model and kinetic parameters of the degradation process. The system was found to be comprised of three main species and best characterized by two consecutive first-order reactions. Furazidin degradation rate was found to be highly dependent on the applied environmental conditions, showing more prominent differences between both degradation steps towards higher pH and temperature. Complim…

Antimonic acid hydrate xerogels as proton electrolytes

1993

Abstract Two high stability types of protonic solid electrolytes based on antimonic acid hydrate xerogels have been obtained by the sol-gel technique: Sb 2 O 5 ·(3–4)H 2 O (colloidal) and Sb 2 O 5 ·5H 2 O (polymeric). The first one is a white compact material with conductivity 0.40 mS/cm (298 K) for n =3.7. The last one is transparent for visible light with a conductivity of 0.80 mS/cm. An electrochromic system based on the colloidal gel electrolyte in the form of paste has good performance-more than 10 7 cycles and a lifetime of more than five years.

Injective Fitting sets in automorphism groups

1993

Segregation of copper oxide on calcium copper titanate surface induced by Graphene Oxide for Water splitting applications

2020

Abstract Photoelectrochemical cells (PEC) are promising devices for hydrogen production via sunlight energy. One of the important challenges in this area is to design photoactive electrodes able to absorb visible light. A good photoelectrochemical behavior depends on the presence of surface active sites to photogenerate current at the lower possible potential for water splitting. Recent investigations in this field are focusing on perovskite materials such as CaCu3Ti4O12 (CCTO) as visible light active electrode due its outstanding structure in which CCTO encloses in its structure a visible light absorbance component (CuO). The presence CuO on the material surface is mainly responsible for t…

Coupled cluster calculations of the vertical excitation energies of tetracyanoethylene

2003

The vertical spectrum of tetracyanoethylene was studied using coupled cluster theory. It was found that the lowest singlet-singlet transition, which corresponds to the excitation from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) excitation, occurs at 5.16 eV in the gas phase and is lowered approximately 0.1 eV due to solvent effects in acetonitrile. A parallel study on the ethene spectrum showed the quality of the basis sets and methods used, by placing the V state 7.92 eV above the ground state and giving an energy for the 0-0 transition of 5.42 eV to be compared with the experimental value of 5.50 eV.

La consagración de los derechos fundamentales: de principios generales a texto fundacional de la Unión Europea

2014

<p>El autor argumenta que el reconocimiento formal de los derechos fundamentales como parte de los fundamentos comunes de la UE mediante la remisión a la Carta de los Derechos Fundamentales en el Tratado de Lisboa (otorgándole carácter vinculante y, por ende, elevando su rango y confiriéndole el mismo valor jurídico que los Tratados) ha proporcionado una mayor apariencia constitucional a la UE, pero no un nivel más generoso de protección y de disfrute de la ciudadanía. En efecto, además de haber prescindido de garantías específicas, la Carta de la UE ha introducido diversas asimetrías inaceptables, tales como la quiebra del principio de indivisibilidad (los derechos civiles y los soci…

Synthesis, spectroscopic, cyclic voltammetry properties and molecular structure of the thiocyanato-N meso-tetratolylporphyrinato zinc(II) ion complex

2017

International audience; This paper describes the synthesis of the (thiocyanato-N)(meso-tetratolylporphyrinato)zinc(II) chlorobenzene monosolvate complex with the formula [K(2,2,2-crypt)][Zn(TTP)(NCS)]·C6H5Cl (I) using the cryptand-222 to solubilize potassium thiocyanate in chlorobenzene solvent. Complex (I) has been characterized by elementary analysis, IR, UV–vis, 1H NMR and MS, and the structure of this new zinc(II) metalloporphyrin been examined crystallographically. A cyclic voltammetry investigation was also carried out on this species. The title compound crystallizes in the triclinic, space group P-1, with a = 11.5151(7) Å, b = 15.212(10) Å, c = 20.1093(12) Å, α = 80.428(4)°, β = 74.9…