Fixed points of (α,ψ)‐contractions in Hausdorff partial metric spaces

The concept of (α,ψ)‐contractions was introduced by Samet et al. in this paper, we introduce (α,ψ)‐generalized contractions in a Hausdorff partial metric space. We discuss its significance and obtain some common fixed point theorems for a pair of self‐mappings. Some examples are given to support the theory.     

Synthesis of poly(2-acetamidoacrylic acid) and its PEGMA block copolymer via ATRP in water

Controlled polymerization of a captodative monomer, 2-acetamidoacrylic acid (AAA), was studied for the first time in the literature. Salt of the monomer in water was polymerized using ATRP method and influence of several factors, including solvent composition, halogen exchange and additives like pyridine and halide salts were investigated to improve the control. Captodative monomers form very stable radicals favoring the active species over the dormant one. Depolymerization at room temperature under ATRP conditions was determined as the major obstacle in front of the high molecular weight polymers and block copolymer formation. Nevertheless, poly(AAA-b-(AAA-co-PEGMA)) block polymers were prepared through ATRP and possible applications were discussed. As an example, pH responsive nature and ability to coat superparamagnetic iron oxide nanoparticles were demonstrated.     

Fine and hyperfine structure in the atomic spectrum of niobium

A parametric analysis of the fine and the magnetic dipole hyperfine structure for the three configurations of odd parity 4d³5s5p, 4d⁴5p and 4d²5s²5p was performed. Effective one-electron parameters were determined and theoretical predictions are given for the magnetic dipole hyperfine structure constants A for the levels of these three configurations. Additionally, 12 new energy levels could be found, four of odd and eight of even parity, by re-analysing data for experimental wavelengths of Nb.     

Determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using zirconium containing chemical modifiers.

A method for direct determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using Zr, Ir, etylenediamine acetic acid (EDTA), Zr + EDTA, Ir + EDTA, Zr + Ir and Zr + Ir + EDTA as chemical modifiers in 0.5% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent was developed. The effects of mass and mass ratio of modifiers on analytes in sample solutions were studied. The optimum masses and mass ratios of modifiers: 20 microg of Zr, 4 microg of Ir, 100 microg of EDTA and 20 microg of Zr + 4 microg of Ir + 100 microg of EDTA, were used to enhance the analyte signals. Pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, and detection limits of analytes in samples were compared in the presence or absence of a modifier. The detection limits and characteristic masses of analytes in a 0.5% (m/v) dissolved sample (dilution factor of 200 ml g(-1)) obtained with Zr + Ir + EDTA are 8.0 ng g(-1) and 1.2 pg for Cd, 61 ng g(-1) and 4.3 pg for Cr, 32 ng g(-1) and 23 pg for Cu, and 3.4 ng g(-1) and 19 pg for Pb, respectively. The Zr + Ir + EDTA modifier mixture was found to be preferable for the determination of analytes in sediment and soil-certified and standard reference materials. Depending on the sample type, the percent recoveries of analytes were increased from 81 to 103% by using the proposed modifier mixture; the results obtained are in good agreement with the certified values.     

Erratum: Resolving the sign ambiguity in the singular value decomposition

J. Chemometrics 22 (2): 135–140. DOI: 10.1002/cem.1122 It has come to our attention that an error arose during correction of this article. In Figure 3, Step 3 should as appear as follows:

     

Resolving the sign ambiguity in the singular value decomposition

Many modern data analysis methods involve computing a matrix singular value decomposition (SVD) or eigenvalue decomposition (EVD). Principal component analysis is the time‐honored example, but more recent applications include latent semantic indexing (LSI), hypertext induced topic selection (HITS), clustering, classification, etc. Though the SVD and EVD are well established and can be computed via state‐of‐the‐art algorithms, it is not commonly mentioned that there is an intrinsic sign indeterminacy that can significantly impact the conclusions and interpretations drawn from their results. Here we provide a solution to the sign ambiguity problem and show how it leads to more sensible solutions. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and evaluation of new pyrazoline‐thiazole derivatives as monoamine oxidase inhibitors

A novel series of 1,3,5‐trisubstituted‐2‐pyrazoline derivatives ( 4a ‐ 4k ) was synthesized and their chemical structures characterized by ¹H NMR, ¹³C NMR, and mass spectroscopy. These compounds were evaluated as inhibitors for of type A and type B monoamine oxidase (MAO) enzymes. The most common inhibitors of MAO enzymes used to treat depression and anxiety such as selegiline and moclobemide drugs were used as reference agents. A result of biological evaluation of these compounds revealed compounds 4c , 4d , and 4? as potent and selective MAO A inhibitors. The most active compound 4? , which is 2,4‐dimethoxy at phenyl ring, showed strong inhibitory activity at MAO A (IC₅₀ of 0.0445 ± 0.0018μM). Furthermore, compounds 4c and 4d showed significant inhibition profile on MAO A with the IC₅₀ values 0.1423 ± 0.0051μM and 0.2148 ± 0.0067μM, respectively.     

Accumulation of90Sr in sheep bones from different regions of Turkey

In this study, the accumulation of⁹⁰Sr in front leg bones of sheep (meta carpus), which were 1–6 years old and originated from different regions of Turkey, was investigated. It was shown that⁹⁰Sr activity strongly depends on the age of the sheep as well as on its origin. Since⁹⁰Sr is produced during the fissioning process of uranium isotopes in nuclear reactions, the effect of radiation due to nuclear bomb experiments, nuclear reactor accidents or other radioactive pollutants in different regions of Turkey can be concluded from the results obtained.     

Accumulation of Sr in various bones of animal skeleton

In this study, the accumulation of Sr in various bones of animal skeleton were investigated. Data on the elemental content of Sr in animal skeleton are important for the distribution of radiostrontium. Sr is chemically similar to Ca and therefore the concentrations level of Sr were calculated on a Ca weight basis in the animal skeleton.     

Syntheses and structural characterizations of a new benzyl(4-methoxyphenyl)dithiophosphinic acid and its Ni(II), Co(II), Zn(II), Cd(II), and Ni–pyridine complexes

Benzyl(4-methoxyphenyl)dithiophosphinic acid (HL) was obtained as solid and was treated with the NiCl₂6H₂O, CoCl₂6H₂O, ZnCl_2, and CdCl₂ to prepare its Ni(II), Co(II), Zn(II), and Cd(II) complexes. The nickel complex was further treated with pyridine which led to the formation of octahedral dipyridine derivative. HL was obtained through the addition reaction of the perthiophosphonic acid anhydride Lawesson reagent, (LR), [2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide], with the corresponding Grignard compound (benzylmagnesium bromide) in diethyl ether medium.

The complexes were all of the stoichiometry of [M(L)₂]_x, with x = 1 for M = Ni²⁺ and x = 2 for M = Co²⁺, Cd²⁺ and Zn²⁺. The coordination geometry was square planar in the nickel(II) complex and tetrahedral in the others. Similar to many other nickel(II) complexes, the Ni(L)₂ reacts reversibly with pyridine to yield the octahedral complex ({(Py)₂Ni(L)₂}).

The compounds were characterized by elemental analysis; MS, FTIR, and Raman spectroscopies. The magnetic susceptibilities of the complexes were measured to confirm the hybridization patterns and the geometries. Single-crystal X-ray analyses of Ni(L)₂ and [Co(L)₂]₂ complexes were also carried out to prove the molecular topologies.