CRYSTAL STRUCTURE AND X-RAY CRYSTALLOGRAPHIC ANALYSIS OF THE BINUCLEAR CLUSTER THIOCYANATE COMPLEX OF NIOBIUM(IV)

Journal of Structural Chemistry - The structure of a binuclear niobium(IV) thiocyanate complex (Bu4N)4[Nb2(μ2-S2)2(NCS)8]·H2O (1·H2O) is studied by X-ray crystallography. Compound...     

Dilute-and-shoot approach for determination of several biomarkers and pharmaceuticals in wastewater using nanoflow liquid chromatography – Orbitrap mass spectrometry

A new method for quantitative analysis of several biomarkers and pharmaceutical compounds in wastewater has been developed employing nanoflow liquid chromatography with Orbitrap mass spectrometry. An easy dilute-and-shoot approach has been used for sample preparation with a dilution factor of 5. Improved retention of ionic and highly polar compounds has been achieved by the addition of tetrabutylammonium bromide as an ion pair reagent into the final diluted sample. The new nanoflow liquid chromatography method has demonstrated low matrix effects (70%–111%), high sensitivity in terms of limits of quantification (0.005 to 0.3 μg/L), low injection volume (70 nl) and solvent consumption, and the ability to analyze diverse polar and ionic analytes within one run using a single reversed-phase nanoflow liquid chromatography column. Wastewater samples (n = 116) from the wastewater treatment plants of different cities in Latvia were analyzed using the developed method. The observed concentrations of biomarkers were in line with the literature data.     

Nitropyridines as 2π-Partners in 1,3-Dipolar Cycloadditions with N-Methyl Azomethine Ylide: An Easy Access to Condensed Pyrrolines

1,3-Dipolar cycloaddition reactions of 2-substituted 5-R-3-nitropyridines and isomeric 3-R-5-nitropyridines with N-methyl azomethine ylide were studied. The effect of the substituent at positions 2 and 5 of the pyridine ring on the possibility of the [3+2]-cycloaddition process was revealed. A number of new derivatives of pyrroline and pyrrolidine condensed with a pyridine ring were synthesized.     

Highly Sensitive to Methane Sensor Materials Based on Nano-Pd/SnO2

Theoretical and Experimental Chemistry - Catalytic activities of nanomaterials based on tin dioxide with various palladium contents in the oxidation of CH4 and sensitivities of adsorption...     

Ruthenium-Catalyzed Hydrogenative Degradation of End-of-Life Poly(lactide) to Produce 1,2-Propanediol as Platform Chemical

The chemical recycling of end-of-life polymers can add some value to a future circular economy. In this regard, the hydrogenative degradation of end-of-life PLA was investigated to produce 1,2-propanediol as product, which is a useful building block in polymer chemistry. In more detail, the commercially available Ru-MACHO-BH complex was applied as catalyst to degrade end-of-life PLA efficiently to 1,2-propanediol under mild conditions. After investigations of the reaction conditions a set of end-of-life PLA goods were subjected to degradation.     

Generation of new landomycins by combinatorial biosynthetic manipulation of the LndGT4 gene of the landomycin E cluster in S. globisporus

A 3 kb DNA fragment from the Streptomyces globisporus 1912 landomycin E (LaE) biosynthetic gene cluster (lnd) was completely sequenced. Three open reading frames were identified, lndGT4, lndZ4, and lndZ5, whose probable translation products resemble a glycosyltransferase, a reductase, and a hydroxylase, respectively. Studies of generated mutants from disruption and complementation experiments involving the lndGT4 gene allowed us to determine that LndGT4 controls the terminal L-rhodinose sugar attachment during LaE biosynthesis and that LndZ4/LndZ5 are responsible for the unique C11-hydroxylation of the landomycins. Generation of the novel landomycins F, G, and H in the course of these studies provided evidence for the flexibility of lnd glycosyltransferases toward their acceptor substrates and a basis for initial structure-activity relationships within the landomycin family of antibiotics.     

Topological Limit of Trajectories of Intervals of Simplest One-Dimensional Dynamical Systems

We consider dynamical systems generated by continuous maps of an interval into itself. We investigate the asymptotic behavior of the trajectories of subsets of the interval. In particular, we prove that if the -limit set of an arbitrary trajectory is a fixed point, then the topological limit of the trajectory of any subinterval exists.     

On the lowest order electroweak corrections to spin-12 fermion scattering: (I). The one-loop diagrammar

Based on a gauge model of the electroweak interaction the total set of all one-loop diagrams for scattering of $\text{spin}\text{-}\text{1}\text{2}$ fermions is calculated. Throughout the calculations, the type of fermions (?, ν, …) and of heavy vector bosons (W^±Z⁰, …) is not specified. Derivation of finite parts of each diagram is carried out under the restriction that all invariants of the amplitude are much larger than all fermion masses squared. This allows us to use the expression obtained at arbitrary high energies where weak and electromagnetic interaction strengths are comparable.