Composition,properties, and application of products formed in oxidation of polyethylene by nitric acid

Structure of products formed in polyethylene oxidation by nitric acid was studied by NMR, IR, and electronic absorption spectroscopies and derivatography.     

Preparation of activated carbon from a renewable bio-plant of Euphorbia rigida by H2SO4 activation and its adsorption behavior in aqueous solutions

The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H₂SO₄. The surface area of chemically modified activated carbon was 741.2 m² g⁻¹. The surface characterization of both plant- and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g⁻¹ at 40° C. The adsorption kinetics of methylene blue obeys the pseudo-second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.51 kJ mol⁻¹. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes.     

The manganese(III) complex with chelating Schiff base ligand: X-ray structure,spectroscopic and computational studies

A new Mn(III) complex, [MnCl(H₂O)(L)]·H₂O·C₂H₅OH, where L = 2,2′-{1,2-phenylenebis[nitrilomethylylidene]}bis(6-methoxyphenolate), has been synthesized and characterized by single-crystal X-ray diffraction. There is a good agreement between calculated and experimental structural data. The complex is crystallized in orthorhombic with space group Pbca. The Mn1 atom is coordinated with one Schiff base ligand, one water molecule and one chloride anion, forming a six-coordination number. The electronic and fluorescence spectra of the complex were also studied.     

In vitro anticancer activity of binuclear Ru(II) complexes with Schiff bases derived from 5-substituted salicylaldehyde and 2-aminopyridine with notably low IC50 values

The binuclear Ru(II) complexes with Schiff bases derived from 5-chlorosalicyladehyde and 2-aminopyridine and its 5-substituted salicylideneimine homologues were tested in vitro against cervical carcinoma (HeLa), metastatic colorectal adenocarcinoma (SW620), lung adenocarcinoma (A549), breast adenocarcinoma (MCF-7), and human lung fibroblast (WI-38) cell lines. All compounds showed strong antiproliferative activity with extremely low IC₅₀ values. The compounds expressed strong activity against gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis.     

Heteroleptic ruthenium bioflavonoid complexes: from synthesis to in vitro biological activity

Heteroleptic ruthenium(II) bioflavonoid complexes of quercetin, morin, chrysin, and 3-hydroxyflavone were prepared and their interaction with CT DNA and BSA along with antioxidant and in vitro anticancer and antimicrobial activities was investigated. The formulation and characterization of complexes were achieved through elemental and thermal analysis, mass spectrometry, ¹H NMR spectroscopy along with infrared, electronic absorption, and emission spectroscopy as well as square-wave voltammetry, and magnetic and conductivity measurements. Ruthenium(II) is octahedrally coordinated in cationic complex species to two bidentate diimine ligands (2,2′-bipyridine or 1,10-phenanthroline) and one bidentate monobasic flavonoid ligand through 3,4-site of quercetin, morin, and 3-hydroxyflavone or 4,5-site of chrysin. Complexes bind CT DNA by intercalation and binding constants comparable to ethidium bromide or 10 times higher. Binding constants of complexes to BSA were several times higher compared to ibuprofen and diazepam, and suggest that the complexes have a strong affinity to BSA. Antioxidant activity tests showed that the complexes are more potent in terms of radical inhibition compared to the parent flavonoids. Cytotoxic testing revealed that the Ru(II) complex of quercetin with 2,2′-bipyridine co-ligand has good selectivity to breast adenocarcinoma, while the complex of 3-hydroxyflavone with 2,2′-bipyridine co-ligand showed strong cytotoxicity toward all tested cell lines with IC₅₀ ～ 1 μM. All complexes showed moderate activity toward Acinetobacter baumannii, while the Ru(II) complex of 3-hydroxyflavone with 2,2′-bipyridine showed excellent activity toward MRSA and Candida albicans.     

Kinetics of Oxidation of L‐Cysteine by trans‐ and cis‐CoIII and FeIII Complexes based on α‐ and γ‐Diimine Schiff Base Ligands

Kinetics of oxidation of L ‐cysteine by Co^III and Fe^III complexes based on α‐ and γ‐diimine Schiff base ligands were studied in aqueous solution. Pairs of trans and cis isomers of the metal complexes were used in the studies. Kinetic measurements were performed at 25 °C and constant pH and ionic strength under pseudo‐first order condition, in which the concentration of cysteine was around two orders of magnitude greater than that of the metal complex. The observed rate constant was obtained by following the change in absorbance of the reaction mixture with time at a predetermined wavelength. The overall rate constant and order of the reaction with respect to cysteine and metal complex were determined. For both metal ions studied, the oxidation rate constant for the trans isomer was higher than that for the cis isomer. This was attributed to the contribution of the steric factor and the trans effect. The effects of substituents and the nature of the metal ion on the reaction rate are discussed.     

An online nano‐LC‐ESI‐FTICR‐MS method for comprehensive characterization of endogenous fragments from amyloid β and amyloid precursor protein in human and cat cerebrospinal fluid

Amyloid precursor protein (APP) is the precursor protein to amyloid β (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD). Endogenous Aβ peptides reflect the APP processing, and greater knowledge of different APP degradation pathways is important to understand the mechanism underlying AD pathology. When one analyzes longer Aβ peptides by low‐energy collision‐induced dissociation tandem mass spectrometry (MS/MS), mainly long b‐fragments are observed, limiting the possibility to determine variations such as amino acid variants or post‐translational modifications (PTMs) within the N‐terminal half of the peptide. However, by using electron capture dissociation (ECD), we obtained a more comprehensive sequence coverage for several APP/Aβ peptide species, thus enabling a deeper characterization of possible variants and PTMs. Abnormal APP/Aβ processing has also been described in the lysosomal storage disease Niemann–Pick type C and the major large animal used for studying this disease is cat. By ECD MS/MS, a substitution of Asp7 → Glu in cat Aβ was identified. Further, sialylated core 1 like O‐glycans at Tyr10, recently discovered in human Aβ (a previously unknown glycosylation type), were identified also in cat cerebrospinal fluid (CSF). It is therefore likely that this unusual type of glycosylation is common for (at least) species belonging to the magnorder Boreoeutheria. We here describe a detailed characterization of endogenous APP/Aβ peptide species in CSF by using an online top‐down MS‐based method. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,Crystal Structure and Luminescent Properties of Some Zn(II) Schiff Base Complexes: Experimental and Computational Study

A series of Zn(II)-Schiff bases I, II and III complexes were synthesized by reaction of o-phenylenediamine with 3-methylsalicylaldehyde, 4-methylsalicylaldehyde and 5-methylsalicylaldehyde. These complexes were characterized using FT-IR, UV-Vis, Diffuse reflectance UV-Vis, elemental analysis and conductivity. Complex III was characterized by XRD single crystal, which crystallizes in the triclinic system, space group P-1, with lattice parameters a?=?9.5444(2) Å, b?=?11.9407(2) Å, c?=?21.1732(3) Å, V?=?2390.24(7) ų, D _c ?=?1.408 Mg m^?3, Z?=?4, F(000)?=?1050, GOF?=?0.981, R1?=?0.0502, wR2?=?0.1205. Luminescence property of these complexes was investigated in DMF solution and in the solid state. Computational study of the electronic properties of complex III showed good agreement with the experimental data.     

Determination of polyphenol component fractions and integral antioxidant capacity of Syrian aniseed and fennel seed extracts using GC–MS,HPLC analysis,and photochemiluminescence assay

The chemical components of both Syrian aniseed and fennel seeds collected from Idlib and Aleppo regions were identified using GC/MS spectrometry. Thirty-four component fractions representing an average of 98.5% of anise seed extract were characterized. The major average components were (E)-Anethole, Estragole, Limonene, Fenchone, Linalool, para-Anisaldehyde, (Z)-Anethole, and methyl chavicol. Also, thirty-one component fractions representing an average of 99.46% of fennel seed extract were identified. The major components were α-Pinene, α-Phellandrene, Fenchone, Methyl chavicol, Estragole, (Z)-Anethole, Limonene, 1,8-Cineole, Anisole-p-allyl, E,E-Farnesene, Estragole, (E)-Anethole, Anisaldehyde, and Carvacrol. The extract of aniseed was characterized by higher amounts of trans-anethole (52.2%) than fennel extract (38.3%). The integral antioxidant capacity (IAC) of two different extracts from both aniseed and fennel seeds have been determined using photochemiluminescence assay (PCL). The sum of antioxidant capacity (IAC) of hydrophilic and hydrophobic components in both aniseed and fennel seeds was determined, as a total equivalent per gram of dry material (nmolTE/gDM) at 166.69 ± 0.42 and 363.28 ± 1.11 nmol for hydrophilic and hydrophobic components, respectively. Eight major phenolic compounds known as possible antioxidant sources with their concentrations have been identified in both aniseed and fennel seeds by HPLC and GC–MS analysis.