Occurrence and Characteristics of Staphylococcus aureus Isolated from Dairy Products

Food, particularly milk and cheese, may be a reservoir of multi-drug resistant Staphylococcus aureus strains, which can be considered an important issue in terms of food safety. Furthermore, foods of animal origin can be a cause of staphylococcal food poisoning via the production of heat-stable enterotoxins (SE). For this reason, we investigated the prevalence of and characterized Staphylococcus aureus strains isolated from milk and fresh soft cheese obtained from farms located in Wielkopolskie and Zachodniopomorskie Provinces in Poland. Overall, 92% of S. aureus isolates were positive for at least one of the 18 enterotoxin genes identified, and 26% of the strains harbored 5 to 8 enterotoxin genes. Moreover, the S. aureus strains contained genes conferring resistance to antibiotics that are critically important in both human and veterinary medicine, i.e., β-lactams (mecA), aminoglycosides (aac(6′)/aph(2″), aph(3′)-IIIa, ant(4′)-Ia) and MLS_B (erm(A), msr(A), lun(A)). The antimicrobial susceptibility of S. aureus to 16 antibiotics representing 11 different categories showed that 74% of the strains were resistant to at least 1 antibiotic. Moreover, 28% of the strains showed multidrug resistance; in particular, two methicillin-resistant S. aureus strains (MRSA) exhibited significant antibiotic resistance. In summary, our results show that dairy products are contaminated by S. aureus strains carrying genes encoding a variety of enterotoxins as well genes conferring resistance to antibiotics. Both MRSA strains and MSSA isolates showing multidrug resistance were present in foods of animal origin.     

Mechanochemical Synthesis of Fluorinated Imines

A number of imines, including 12 new compounds, previously not reported in the literature, derived from variously fluorinated benzaldehydes and different anilines or chiral benzylamines were synthesized by a solvent-free mechanochemical method, which was based on the manual grinding of equimolar amounts of the substrates at the room temperature. In a very short reaction time of only 15 min, the method produced the expected products with good-to-excellent yields. The yields were comparable or significantly higher than those reported in the literature for the imines synthesized by other methods. Importantly, the conditions used for the reactions with aniline derivatives also resulted in the high yields of imines obtained from chiral benzylamines, and can be extended to the synthesis with other similar amines. Structures of all imines were confirmed by NMR spectroscopy: ¹H, ¹³C and ¹⁹F. For four compounds, X-ray structures were also obtained. The synthetic approach presented in this paper contributes to the prevention of environmental pollution and can be easily extended for larger-scale syntheses. The mechanochemical solvent-free method provides a convenient strategy particularly useful for the preparation of fluorinated imines being versatile intermediates or starting material in the synthesis of drugs and other fine chemicals.     

Photoelectrochemical Properties of Annealed Anodic TiO2 Layers Covered with CuOx

In this work, we present a systematic study on the influence of Cu²⁺ ion concentration in the impregnation solution on the morphology, structure, optical, semiconducting, and photoelectrochemical properties of anodic CuO_x-TiO₂ materials. Studied materials were prepared by immersion in solutions with different concentrations of (CH₃COO)₂Cu and subjected to air-annealing at 400 °C, 500 °C, or 600 °C for 2 h. The complex characterization of all studied samples was performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), reflectance measurements, Mott–Schottky analyses, and photocurrent measurements. It was found that band gap engineering based on coupling CuO with TiO₂ (E_g~3.3 eV) is an effective strategy to increase the absorption in visible light due to band gap narrowing (CuO_x-TiO₂ materials had E_g~2.4 eV). Although the photoactivity of CuO-TiO₂ materials decreased in the UV range due to the deposition of CuO on the TiO₂ surface, in the Vis range increased up to 600 nm at the same time.     

Coordination chemistry of H-spirophosphorane ligands towards pentacarbonylchlororhenium(I) – synthesis,structure and catalytic activity of complexes

Synthesis of a group of carbonyl rhenium coordination compounds with hydrospirophosphorane ligands was carried out and described. Different symmetrical HP(OCH₂CH₂NH)₂ L1 , HP(OCH₂CMe₂NH)₂ L2 , HP(OC₆H₄NH)₂ L3 , and unsymmetrical ligands HP (OCMe₂CMe₂O)(OC₆H₄NH) L4 were found to coordinate to the rhenium center as bidentate P,N donor ligands yielding fac-[ReCl (CO)₃ Ln ], where n = 1 – 4. Furthermore, monodentate coordination was also observed in some cases, as was clearly presented in the case of [ReCl(CO)₂( L4- κ²P,N)( L4- κP)] complex. All of the complexes were characterized using optical spectroscopy. Single-crystalX-ray diffraction was also performed in the case of fac-[ReCl(CO)₃ L3 ], fac-[ReCl(CO)₃ L4 ], [Re(CO)₂( L2 )₂]Cl and [ReCl (CO)₂( L4- κ²P,N)( L4- κP)] samples. Complexes [ReCl(CO)₃ L3 ] and [ReCl (CO)₃ L4 ], both bearing rings of conjugated double bonds within hydrospirophosphorane ligands, exhibited luminescence. Catalytic properties of rhenium complexes were assessed using the representative fac-[ReCl (CO)₃ L2 ] complex in the dimerization reaction of terminal alkynes. An efficient and selective procedure for synthesis of the E - enynes was developed. Coupling of (2-chlorophenyl)acetylene was mediated by [ReCl (CO)₃ L2 ]/TBAF system with a 100% conversion rate. Different substituents within aromatic alkynes were tolerated and the resulting products were dependent on the nature of the substituents.     

Slice modules over minimal 2-fundamental algebras

We consider a class of algebras whose Auslander-Reiten quivers have starting components that are not generalized standard. For these components we introduce a generalization of a slice and show that only in finitely many cases (up to isomorphism) a slice module is a tilting module. The first named author was supported by the Polish Scientific Grant KBN No 1 P03A 018 27     

Voltammetric Determination of 3‐Nitrofluoranthene and 3‐Aminofluoranthene at Boron Doped Diamond Thin‐Film Electrode

The voltammetric behavior of 3‐nitrofluoranthene and 3‐aminofluoranthene was investigated in mixed methanol‐water solutions by differential pulse voltammetry (DPV) at boron doped diamond thin‐film electrode (BDDE). Optimum conditions have been found for determination of 3‐nitrofluoranthene in the concentration range of 2×10^?8–1×10^?6 mol L^?1, and for determination 3‐aminofluorathnene in the concentration range of 2×10^?7–1×10^?5 mol L^?1, respectively. Limits of determination were 3×10^?8 mol L^?1 (3‐nitrofluoranthene) and 2×10^?7 mol L^?1 (3‐aminofluoranthene).     

Determination of thermodynamic properties of isotactic poly(1-butene) at infinite dilution using density and inverse gas chromatography

The partial molar volumes, V1(M), and the molar volume of isotactic crystalline low-molecular-weight poly(1-butene), iPBu-1, V1, have been calculated from the measured density of {iPBu-1 + solvent (n-hexane, n-heptane, n-nonane, n-decane, p-xylene, cyclohexane and chloroform)} systems. Some of the thermodynamic quantities were also obtained for the iPBu-1 with eight hydrocarbons (n-octane, n-decane, n-undecane, n-dodecane, n-tridecane, o-xylene, m-xylene, p-xylene) by the method of inverse gas chromatography at various temperatures. The weight fraction activity coefficients of the solvent at infinite dilution, omega2(infinity) and the Flory-Huggins thermodynamic interaction parameters, chi21(infinity), between polymer and solvents were determined. The partial molar free energy, deltaG2(infinity), the partial molar heat of mixing, deltaH2(infinity), at infinite dilution and the polymer solubility parameter, delta1, were calculated. Additionally, the (solid + liquid) binary mixtures equilibria, SLE, of iPBu-1 with three hydrocarbons (n-octane, n-decane and m-xylene) were studied by a dynamic method. By performing these experiments over a large concentration range, the T-x phase diagrams of the polymer-solvent systems were constructed. The excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase. The omega2(infinity) were determined from the solubility measurements and were predicted by using the UNIFAC FV model.     

A supramolecular polymeric chain in the cobalt(II) complex with diclofenac: synthesis,crystal structure,spectroscopic, thermal and antioxidant activity

Abstract

A cobalt(II) complex with empirical formula [Co(dicl)₂·(H₂O)₃]·MeOH (where dicl?=?diclofenac) was synthesized and characterized by elemental analysis, flame atomic absorption spectroscopy (FAAS), infrared spectroscopy (FTIR) and thermal decomposition techniques (TGA). The crystal structure of the complex was determined by single crystal X-ray diffraction technique. The compound crystallizes in the monoclinic space group I2/a. Apical water molecules link adjacent cobalt(II) ions forming polymeric chains along the crystal a axis. The thermal behavior of the complex was studied by TG/DTG/DTA, TG/MS and TG/FTIR methods under non-isothermal conditions in air. Upon heating [Co(dicl)₂·(H₂O)₃]·MeOH decomposes progressively to metal oxides, which are the final products of pyrolysis. Furthermore, antioxidant activity of the complex was examined.