Volume 63, Issue 5

Both synthetic and biologically produced magnetic nano- and microparticles exhibit several types of responses to external magnetic field which have been already employed in various areas of biosciences, biotechnology, medicine, environmental technology, etc. This short review shows selected important biotechnological applications of magnetic particles, and the biological processes leading to biogenic magnetic particles formation.

It is well known that traditional Chinese medicine (TCM) plays a more and more important role in modern pharmaceutical industry. It has been used in the therapy of many diseases for several thousand years because of its high pharmacological activity, low toxicity and rare side effects. In TCM, as an important group of secondary metabolites, essential oils have attracted a great deal of attention in recent years. Gas chromatography-mass spectrometry (GC-MS) is the most commonly used technique for the analysis of liposoluble constituents, especially volatile/semi-volatile compounds, and their metabolites in biological fluids due to its high resolution, selectivity and sensitivity. This review briefly describes the applications of GC-MS for the isolation and characterization of volatile compounds from TCM. In addition, GC-MS methods adopted in the metabolic profiling of volatile compounds in biological matrices are also described.

Determination of copper using inductively coupled plasma mass spectrometry (ICP-MS) suffers from polyatomic overlays originating from Na+ and Mg2+ matrix elements due to the formation of 40Ar23Na+ and 40Ar25Mg+ in the mass-to-charge ratios of 63 and 65, respectively. The collision/reaction cell technology belongs to the most modern methods used to overcome polyatomic interferences. Gas-filled collision/reaction cell can cause an additional mass bias effect influencing analytical precision of the method. In this study, the additional mass bias effect of the hexapole collision/reaction cell ICP-MS was studied on an example of n(65Cu)/n(63Cu) isotope ratio. As a result, a method for suppressing polyatomic interference on the mass-to-charge ratio of 63 and 65 was introduced and additional mass bias of the collision/reaction cell was lowered to an acceptable level.

Kinetic data of glucose oxidation in aqueous solution catalyzed by heterogeneous palladium catalyst are presented under conditions of the catalyst reversible deactivation by oxygen. Measurements were run in a semi-continuous stirred tank reactor at 30°C and atmospheric pressure in kinetic regime. Effect of the reaction mixture composition on the reaction rate is presented. The catalyst activation/reactivation technique is discussed and optimized. Relation between optimal activation time and glucose concentration was defined.

Robust static output feedback control was applied to a continuous stirred tank reactor with parametric uncertainty and multiple steady states in which exothermic reaction takes place. The problem of robust controller design was converted to a solution of linear matrix inequalities and a computationally simple non-iterative algorithm is presented. The possibility of using robust static output feedback for stabilization of reactors with uncertainty and comparison of robust P and PI controllers with an optimal controller is demonstrated by simulation results.

The aim of this work was to determine the content of selected heavy metals in flax materials depending on the stage of fiber manufacturing. Non-treated natural fiber composition was compared with that of fibers processed. Changes in the composition of yarn before and after the following scutching, hackling, washing, and bleaching were also investigated. Analysis of heavy metals was performed applying inductively coupled plasma mass spectrometry. Flax material was mineralized in closed Teflon vials with a mixture of concentrated nitric acid which were then placed in a microwave oven system. Analytical quality of the obtained results was checked by the determination of elements in the Certificate Reference Materials of IAEA-V-10. The acquired results proved that the content of metals in flax clearly varies depending on the treatment process applied (bleaching, washing, coloration). Significant differences were also connected with the dye used.

Synthesis, characterization and biological studies of some thiodiamine metal complexes are described. Cobalt(II) and copper(II) complexes of type [Cu(L)2Cl2] and [Co(L)2SO4], where L = (cyclohexyl-N-thio)-1,2-ethylenediamine (L1) and (cyclohexyl-N-thio)-1,3-propanediamine (L2), were synthesized. The synthesized copper and cobalt thiodiamine complexes were characterized by elemental analysis, IR, mass, UV-VIS and 1H NMR spectroscopic studies. Thiodiamines coordinate as a bidentate N-S ligand. The binding sites are azomethine nitrogen and thioamide sulfur. Molar conductance values in dimethylsulfoxide indicate non-electrolyte nature of the complexes. In vitro-antimicrobial screening shows promising results against both bacterial and fungal strains.

In this study, new benzoylthiourea derivatives, (E)-N-[(2-benzamidomethyleneamino)ethylcarbamothioyl]benzamide H3L′, N-(1-(3-benzoylthioureido)propan-2-ylcarbamothioyl)-benzamide H4L″, (E)-N-[4-(benzamidomethyleneamino)phenylcarbamothioyl]benzamide H3L‴, were synthesized. Structures of the compounds were identified by spectroscopic techniques. In addition, all synthesized compounds were evaluated for in vitro antibacterial and antifungal activity. Compound H3L‴ exhibited antibacterial activity.

Nucleolytic activities of some new oxime-type ligand complexes were investigated by neutral agarose gel electrophoresis. Analysis of the cleavage products in agarose gel indicated that all complexes used converted supercoiled pUC18 plasmid DNA to its nicked or linear form. It was found that nucleolytic activities of the complexes depend on the complex concentration, reaction time and the presence of a cooxidant (magnesium monoperoxyphthalate, MMPP) in the reaction mixture. However, the complexes cleaved pUC18 plasmid DNA at all investigated pH values. Nucleolytic activities of complexes were investigated for different complex concentrations (0.1–100 μmol L−1), pH values (6.0–10.0) and reaction times (0–60 min). Molecular modeling studies performed by the Hyperchem Software together with DNA-binding studies showed that planar sites of the complexes intercalated into double stranded DNA. It can be concluded that all oxime-type ligand complexes used can be evaluated as nuclease mimics.

Mechanochemical synthesis of lead selenide PbSe nanocrystals was performed by high-energy milling of lead and selenium powders in a planetary ball mill. The structure properties of synthesized lead selenide were characterized by XRD analysis that confirmed crystalline nature of PbSe nanocrystals. Calculated average size of PbSe crystallites was 37 nm. The methods of particle size distribution analysis, specific surface area measurement, SEM and TEM were used for the characterization of surface and morphology of PbSe nanocrystals. SEM analysis revealed agglomerates of PbSe particles. However, HRTEM analysis confirmed perfect stoichiometric PbSe cubes with NaCl structure as well. UV-VIS-NIR spectrophotometry was used to confirm the blue shift of the small particles occurring in the powder product obtained by the mechanochemical synthesis.

This paper aims to increase the sorption capacity of hydroxyapatite and to find the best apatite-based material for metal ions sorption. The sorption process of copper ions from water solutions by HAP and structurally modified HAP was carried out in this work. Structural modifications of HAP were realized in the preparation phase by an addition of sodium silica into the reaction medium. The prepared materials were characterized by physical-chemical methods: IR, electron-microscopy and X-ray diffraction. The composites characterized were tested in kinetic studies regarding ion exchange and adsorption of Cu2+. It was revealed that the silica content, particle size and initial copper ion concentration influence the process rate.

Corrosion resistance of zinc coatings was investigated in an accelerated corrosion test in a condensation chamber. Zinc was electrodeposited from alkaline and acidic electrolytes using direct current (DC) or pulse current (PC). The zinc coating was subsequently protected against corrosion with a chrome (III) layer. Morphology and structure of the coatings was investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) before and after the corrosion test. Corrosion resistance of alkaline zinc coatings electrodeposited with DC and PC under test conditions was found to be comparable. The corrosion resistance of zinc coatings deposited from acidic electrolytes by PC was lower in comparison with corrosion resistance of zinc coatings deposited using DC.

Multi-wall carbon nanotubes were coated with a conducting polymer, polyaniline phosphotungstate. Such composite structures have mixed electronic and proton conductivity, high surface area and porosity. These materials were decorated with catalytically-active noble metals — Pt, Pd, and Rh. Metal nanoparticles were uniformly distributed in the polymer matrix. Such ternary composites can be considered as electrode materials in sensors, electrolysers, supercapacitors, and especially in low-temperature fuel cells with a proton-conducting polymer membrane.

2-[3-(Trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (I) was prepared by a three-step synthesis. Its reaction with phosphorus sulfide rendered thione II which was methylated to 2-[3-(Trifluoromethyl)phenyl]-4-methylsulfanylfuro[3,2-c]pyridine (III). 5-Methyl-2-[3-(trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (IV) was obtained by the reaction of I with methyl iodide in PTC conditions. The chlorine atom in derivate V was replaced with heterocyclic secondary amines via nucleophilic substitution and 4-substituted furopyridines VIa and VIb were thus prepared. 2-[3-(Trifluoromethyl)phenyl]furo[3,2-c]pyridine-4-carboxylic acid (VII) was obtained by hydrolysis of the corresponding carbonitrile Va.

Dimethylmaleoyl (DMM) moiety has become an important amine protective group in sugar chemistry. We disclose herein that DMM-containing D-glucosamine analogues, because of their electrophilic nature, are prone to reactions with strong nucleophiles, such as hydrazine, resulting in a set of undesired side products that are difficult to detect, yet proved to be problematic for organic synthesis.

Correct prediction of the structure and energetics along the reaction pathway of the formation or dissociation of the glycosidic bond in sugar phosphates is crucial for the understanding of catalytic mechanism and for the determination of transition state structures of sugar-phosphate processing enzymes. The performance of seven density functional theory (DFT) methods (BLYP, B3LYP, MPW1PW91, MPW1K, MPWB1K, M05 and M05-2X) and two wave function methods (HF and MP2) was tested using four structural models with the activated sugar-phosphate α-glycosidic linkage. The models were chosen based on the crystal structure of the retaining glycosyltransferase LgtC complex with methyl α-d-galactopyranose diphosphate and its 2-fluoro derivative. Results of the MP2 method were used as a benchmark for the other methods. Two structural trends were observed in the calculations: predicted length of the activated C1-O1 glycosidic bond of 1.49–1.63 Å was significantly larger than values of a standard C1-O1 glycosidic bond in crystal structures of carbohydrates (1.39–1.48 Å), and the calculated value depended on the DFT method used. The MPW1K, M05 and M05-2X functionals provided results in closest agreement with those from the MP2 method, the difference being less than 0.02 Å in the calculated glycosidic bond lengths. On the contrary, the BLYP and B3LYP functionals failed to predict sugar diphosphate in the (-sc) conformation as a stable structure. Instead, the only stationary points localized along the C1-O1 dissociation coordinate were oxocarbenium ions at the distance of approximately 2.8 Å. The M05-2X, MPW1K and MPWB1K functionals gave the most reasonable prediction of the thermochemical kinetic parameters, where the formation of the oxocarbenium ion has a slightly endothermic character (0.4–1.7 kJ mol−1) with an activation barrier of 7.9–9.2 kJ mol−1.

A new and simple quantitative structure-retention relationship (QSRR) was tested as a predictive model for adjusted retention times in complex petroleum condensate fractions. This relationship adopted the form of a non-linear collective retention-variables model. The adjusted retention times were correlated with the components molecular descriptors, e.g. total path counts and boiling temperatures, by multi-linear regression analysis. The obtained two QSRR models show an acceptable predictive accuracy with R 2 of 0.9949 and 0.9856, respectively. Stability and validity of the models were tested by comparing the calculated and the experimental retention indices.

A surface ionization gas chromatographic detector, based upon positive surface ionization, was used in capillary gas chromatography to sensitively and selectively detect nitro pesticides: pendimethalin, trifluralin, flumetralin. Higher sensitivity (better detection limit), substance specificity, and advantageous applicability are reported. Sensitivity to pendimethalin, trifluralin, and flumetralin was 1.4 C g−1, 1.1 C g−1, and 1.0 C g−1, respectively, with the linear range of operation greater than 1 × 105 for these compounds. The minimum detectable level was in the range of 10−13 g s−1. Compared with an atomic emission detector, SID provided a 110 times better detection limit for trifluralin.

After catalyst screening for oxidative desulfurization of fuel oil within several polyoxometalates, H3PW6Mo6O40 was confirmed for the first time to be an effective and recoverable catalyst for the oxidative removal of thiophene, being also effective for the desulfurization of real diesel and gasoline.

Foaming properties of aqueous solutions of the nonionic surfactant polyoxyethylene dodecyl ether (C12EOn) were studied at 298 K. Four different EO chain lengths, namely C12EO3, C12EO5, C12EO7, and C12EO9, were considered. The foams obtained from C12EO3 or C12EO5 were extraordinary stable retaining a constant volume for more than 20 h. The presence of lamellar liquid crystalline phases was mainly responsible for the super-stable aqueous foams.