Selective and Reversible 1,3-Dipolar Cycloaddition of 2-(2-Oxoindoline-3-ylidene)acetates with Nitrones in the Synthesis of Functionalized Spiroisoxazolidines

The 1,3-dipolar cycloaddition of 2-(2-oxoindoline-3-ylidene)acetates with functionalized aldo- and ketonitrones proceeds with good selectivity to provide new highly functionalized 5-spiroisoxazolidines. A characteristic feature of these reactions is reversibility that allows for the control of the diastereoselectivity of cycloaddition. The reduction of obtained adducts using zinc powder in acetic acid leads to 1,3-aminoalcohols or spirolactones. For a number of the spiro compounds obtained, anticancer activity was found.     

Fluoroplast Doped by Ag2O Nanoparticles as New Repairing Non-Cytotoxic Antibacterial Coating for Meat Industry

Foodborne infections are an important global health problem due to their high prevalence and potential for severe complications. Bacterial contamination of meat during processing at the enterprise can be a source of foodborne infections. Polymeric coatings with antibacterial properties can be applied to prevent bacterial contamination. A composite coating based on fluoroplast and Ag₂O NPs can serve as such a coating. In present study, we, for the first time, created a composite coating based on fluoroplast and Ag₂O NPs. Using laser ablation in water, we obtained spherical Ag₂O NPs with an average size of 45 nm and a ζ-potential of −32 mV. The resulting Ag₂O NPs at concentrations of 0.001–0.1% were transferred into acetone and mixed with a fluoroplast-based varnish. The developed coating made it possible to completely eliminate damage to a Teflon cutting board. The fluoroplast/Ag₂O NP coating was free of defects and inhomogeneities at the nano level. The fluoroplast/Ag₂O NP composite increased the production of ROS (H₂O₂, OH radical), 8-oxogualnine in DNA in vitro, and long-lived active forms of proteins. The effect depended on the mass fraction of the added Ag₂O NPs. The 0.01–0.1% fluoroplast/NP Ag₂O coating exhibited excellent bacteriostatic and bactericidal properties against both Gram-positive and Gram-negative bacteria but did not affect the viability of eukaryotic cells. The developed PTFE/NP Ag₂O 0.01–0.1% coating can be used to protect cutting boards from bacterial contamination in the meat processing industry.     

Pathways of hydrogen photoproduction by immobilized Chlamydomonas reinhardtii cells deprived of sulfur

The green algae Сhlamydomonas reinhardtii entrapped in a thin alginate film have been shown to sustain elevated rates of hydrogen photoproduction under anaerobic incubation in sulfur/phosphorus depleted tris-acetate medium. In the present work we studied mechanisms, underlying hydrogen photoproduction by the immobilized culture, particularly, the roles of PSII and starch accumulation/breakdown. DCMU, a specific inhibitor of electron transport in PSII, is known to suppress hydrogen evolution by circa 80% in suspension cultures of S-deprived C. reinhardtii. In immobilized cells DCMU caused successive stimulatory and inhibitory effects on hydrogen photoproduction, both depending on the deprivation status of the algal cell. The inhibitory effect of DCMU was 25% at 70 h of S deficiency when maximal rates of hydrogen photoproduction were observed. Measurements of the light-induced prompt and delayed chlorophyll fluorescence transients and reflectance at 820 nm (P₇₀₀ redox transitions) revealed very rapid decline of PSII activity in the entrapped S-deprived cells as compared with the suspension culture, whereas PSI suffered less. The immobilized culture showed a high capacity to accumulate starch during early stages of S deprivation and relatively high rates of anaerobic starch degradation during the following hydrogen evolution period. DCMU partly inhibited starch breakdown. Results of the present work brought us to the conclusion that PSII-independent pathway of hydrogen evolution is elevated in the immobilized S-deprived cells rather due to the rapid inactivation of PSII, efficient starch catabolism and non-photochemical PQ reduction.     

Photoswitchable cyan fluorescent protein as a FRET donor

Among a variety of fluorescent proteins available today, there is a lack of suitable markers with excitation/emission in the violet/blue part of visible spectrum. Recently, we reported on photoswitchable cyan fluorescent protein (PS-CFP), which represents monomeric high-contrasting photactivatable label for in vivo protein movement tracking. However, PS-CFP demands high intensity of light for the photoswitching. Therefore it can be employed as a common fluorescent tag at conventional light intensities, which cause negligible or zero photoactivation. High pH stability and unique positioning of excitation/emission peaks make it a worthy supplement to the existing palette of fluorescent proteins. Here we use PS-CFP fusion with a yellow fluorescent protein phiYFP to show that PS-CFP is a promising donor partner for the fluorescence resonance energy transfer (FRET). A remarkable phenomenon is that PS-CFP donor fluorescence turned to be essentially stable with and without FRET, while acceptor emission demonstrated record dynamic range of up to 7.8-fold. This makes the FRET pair presented a useful tool for the single color high throughput screenings. Here we also propose ways for further PS-CFP enhancing, aiming to develop bright cyan fluorescent protein with unique spectral characteristics.     

Soundness and Completeness Proofs by Coinductive Methods

We show how codatatypes can be employed to produce compact, high-level proofs of key results in logic: the soundness and completeness of proof systems for variations of first-order logic. For the classical completeness result, we first establish an abstract property of possibly infinite derivation trees. The abstract proof can be instantiated for a wide range of Gentzen and tableau systems for various flavors of first-order logic. Soundness becomes interesting as soon as one allows infinite proofs of first-order formulas. This forms the subject of several cyclic proof systems for first-order logic augmented with inductive predicate definitions studied in the literature. All the discussed results are formalized using Isabelle/HOL’s recently introduced support for codatatypes and corecursion. The development illustrates some unique features of Isabelle/HOL’s new coinductive specification language such as nesting through non-free types and mixed recursion–corecursion.     

Relationship Conflict,Conflict Management,and Performance of Information Technology Teams

This study examines how team collaboration and goal setting mediate the effects of team relationship conflict and conflict management on team performance. Primary data were collected from students who worked in teams to design functional information systems (IS). The data were then analyzed using structural equations modeling (SEM). The mediators – team collaboration and goal setting – positively affected each other and performance. Full results support a partial mediation model in which 60% of the total effect of relationship conflict and 80% of the total effect of conflict management on team performance are carried through team collaboration and goal setting. This work is the first of its kind that theoretically posits and empirically tests a mechanism through which team conflict and its management relate to team performance.     

On Uniqueness and Properties of Periodic Solution of Second-Order Nonautonomous System with Discontinuous Nonlinearity

We consider an automatic control system with discontinuous nonlinearity of non-ideal relay type and continuous external periodic influence. The control object can be either stable or unstable. In both cases, theorems on sufficient conditions for the existence of a unique periodic solution with given properties are obtained.     

Ontology-based end-user visual query formulation: Why,what, who,how, and which?

Universal Access in the Information Society - Value creation in an organisation is a time-sensitive and data-intensive process, yet it is often delayed and bounded by the reliance on IT experts...