On the Existence of a Classical Optimal Solution and of an Almost Strongly Optimal Solution for an Infinite-Horizon Control Problem

We consider an infinite-horizon optimal control problem with the cost functional described either by an integral over an unbounded interval (a Lebesgue integral) or by a limit of integrals (an improper Lebesgue integral). We prove some theorems on the existence of solutions to such problems. The proofs are based on appropriate lower closure theorems and some extensions of Olech’s theorem on the lower semicontinuity of an integral functional; these extensions cover the cases of functionals described by an integral over an unbounded interval and by a limit of integrals.     

Diurnal variations in the photosynthesis-respiration activity of a cyanobacterial bloom in a freshwater dam reservoir: an isotopic study

The stable isotopic analyses of molecular oxygen dissolved in water (delta18O(DO)) and dissolved inorganic carbon (delta13C(DIC)), supplemented with basic chemical measurements, have been carried out on a diurnal basis to better understand the dynamics of photosynthesis and respiration in freshwater systems. Our observations have been carried out in a lowland dam reservoir, the Sulejow Lake (central Poland), during the summer cyanobacterial bloom. All data obtained, isotopic, hydrochemical, and biological, show a high mutual consistency. Namely, the lowest delta18O(DO) values, obtained at 10:00 and 14:00 (16.0 and 15.5 per thousand, respectively), correspond to the highest amount of cyanobacterial cells observed (66 and 63 mg dm(-3), respectively), whereas the minimum delta13C(DIC) (-10.6 per thousand) obtained at 22:00 corresponds to the maximum content of organic matter (110 mg dm(-3)). This evidence suggests that isotopic assays of delta18O(DO) and delta13C(DIC) are a reliable tool for the quantitative study of biochemical processes in freshwater systems.     

Ground State of the Conformal Flow on 𝕊3

We consider the conformal flow model derived in Bizoń et al. (2017) as a normal form for the conformally invariant cubic wave equation on 𝕊³. We prove that the energy attains a global constrained maximum at a family of particular stationary solutions that we call the ground state family. Using this fact and spectral properties of the linearized flow (which are interesting in their own right due to a supersymmetric structure), we prove nonlinear orbital stability of the ground state family. The main difficulty in the proof is due to the degeneracy of the ground state family as a constrained maximizer of the energy. © 2019 Wiley Periodicals, Inc.     

Protective effect of mitochondrially targeted antioxidant MitoQ on oxidatively stressed fibroblasts

3T3 and VH10 cells were subjected to oxidative damage by hydroxyl radicals generated from Cu(II) ions and ascorbate. The presence of reactive oxygen and nitrogen species in cells was determined using fluorescent dyes. MitoQ—a mitochondrially targeted antioxidant—was examined to prevent cell death and was compared with trolox as a reference standard serving as an antioxidant. MitoQ at lower concentrations (up to 500 nM) prevented damage of mitochondria and thereby increased viability of cells. However, at higher concentrations (over 500 nM) MitoQ decreased the viability of both strains of cells. The last observation indicates that the application of MitoQ should be evaluated also from the point of its cell-destructive potential.     

Aberrant sialylation of a prostate-specific antigen: Electrochemical label-free glycoprofiling in prostate cancer serum samples

Electrochemical detection method allowing to detect prostate-specific antigen (PSA), a biomarker of prostate cancer (PCa), with PSA glycoprofiling was applied in an analysis of PCa serum samples for the first time. Electrochemical impedance spectroscopy (EIS) as a label-free method with immobilized anti-PSA was applied for PSA detection and lectins to glycoprofile captured PSA on the same surface. A proper choice of blocking agent providing high selectivity of biosensor detection with the immobilized anti-PSA antibody was done. The biosensor could detect PSA down to 100 ag/mL with a linear concentration working range from 100 ag/mL up to 1 μg/mL, i.e. 10 orders of concentration magnitude and the sensitivity of (5.5 ± 0.2)%/decade. The results showed that a commercial carbo-free blocking solution was the best one, reducing non-specific binding 55-fold when compared to the immunosensor surface without any blocking agent applied, while allowing to detect PSA. The biosensor response obtained after addition of lectin (i.e. proportional to the amount of a particular glycan on PSA) divided by the biosensor response obtained after incubation with a sample (i.e. proportional to the PSA level in the sample) was applied to distinguish serum samples of PCa patients from those of healthy individuals. The results showed that Maackia amurensis agglutinin (MAA) recognizing α-2,3-terminal sialic acid can be applied to distinguish between these two sets of samples since the MAA/PSA response obtained from the analysis of the PCa samples was significantly higher (5.3-fold) compared to the MAA/PSA response obtained by the analysis of samples from healthy individuals. Thus, combined analysis of serological PSA levels together with PSA glycoprofiling of aberrant glycosylation of PSA (i.e. increase in the level of α-2,3-terminal sialic acid) has a potential to improve detection of PCa.     

Biocompatible Size‐Defined Dendrimer–Albumin Binding Protein Hybrid Materials as a Versatile Platform for Biomedical Applications

For the design of a biohybrid structure as a ligand‐tailored drug delivery system (DDS), it is highly sophisticated to fabricate a DDS based on smoothly controllable conjugation steps. This article reports on the synthesis and the characterization of biohybrid conjugates based on noncovalent conjugation between a multivalent biotinylated and PEGylated poly(amido amine) (PAMAM) dendrimer and a tetrameric streptavidin‐small protein binding scaffold. This protein binding scaffold (SA‐ABDwt) possesses nM affinity toward human serum albumin (HSA). Thus, well‐defined biohybrid structures, finalized by binding of one or two HSA molecules, are available at each conjugation step in a controlled molar ratio. Overall, these biohybrid assemblies can be used for (i) a controlled modification of dendrimers with the HSA molecules to increase their blood‐circulation half‐life and passive accumulation in tumor; (ii) rendering dendrimers a specific affinity to various ligands based on mutated ABD domain, thus replacing tedious dendrimer–antibody covalent coupling and purification procedures.

     

High-Pressure Mechanistic Insight into Bioinorganic NO Chemistry

Pressure is one of the most important parameters controlling the kinetics of chemical reactions. The ability to combine high-pressure techniques with time-resolved spectroscopy has provided a powerful tool in the study of reaction mechanisms. This review is focused on the supporting role of high-pressure kinetic and spectroscopic methods in the exploration of nitric oxide bioinorganic chemistry. Nitric oxide and other reactive nitrogen species (RNS) are important biological mediators involved in both physiological and pathological processes. Understanding molecular mechanisms of their interactions with redox-active metal/non-metal centers in biological targets, such as cofactors, prosthetic groups, and proteins, is crucial for the improved therapy of various diseases. The present review is an attempt to demonstrate how the application of high-pressure kinetic and spectroscopic methods can add additional information, thus enabling the mechanistic interpretation of various NO bioinorganic reactions.     

Polyethyleneimine coating renders polycarbonate resistant to organic solvents

We propose a method for the modification of surfaces of microchannels in chips fabricated in polycarbonate (PC) that makes the devices resistant to a range of organic solvents. Coating of PC with branched polyethyleneimine (BPEI) with the use of trimethylpropane triglycidyl ether (TTE) as a linker renders the devices resistant to toluene, benzene, acetonitrile, tetrahydrofuran, dioxane and ethylene dichloride. The optimized procedure of modification allows for continuous operation of the chips for several hours without dissolution of PC. Additional modification with the use of Krytox? allows for the use of Fluorinert (FC-40) as the continuous phase and for generation and handling of droplets of organic solvents that are miscible with water.