Photocrosslinkable diazoresin/pectin films – Synthesis and application as cell culture supports

Multilayer polymeric films composed of diphenylamine-4-diazoresin (DR), a synthetic polycation, and pectin (Pec), a polyanionic natural polysaccharide, were obtained using a layer-by-layer method (LbL). The films was photocrosslinked by the irradiation with 350 nm light which resulted in their stabilization against different solvents. The nanostructure of the films was studied using AFM microscopy. Irradiation of the films resulted also in the change of the zeta potential of both DR and Pec outermost layer to more negative values and in the increase of the film hydrophobicity as found from the contact angle measurements. The DR/Pec films have been shown to support cell growth and osteogenic potential of cell culture supports in tissue engineering, as found from the experiments with human bone marrow stromal cells (hMSCs).     

Generalized Absolute Values and Polar Decompositions of a Bounded Operator

Generalized absolute values as well as corresponding to them generalized polar decompositions of a bounded linear operator T of a Hilbert space H{\mathcal{H}} into a Hilbert space K{\mathcal{K}} are defined, motivated by the inequality |áTx, y?_K|² ￡ á|T|x, x?_Há|T^*|y, y?_K{|\langle{Tx}, {y}\rangle}_{\mathcal{K}}|^2 \leq \langle|T|x, {x}\rangle_{\mathcal{H}}\langle{|T^{*}|y}, {y}\rangle_{\mathcal{K}} . It is shown that there is a natural bijection between generalized absolute values of T and of T* which sends |T| to |T*|. For a bounded nonnegative operator A on H{\mathcal{H}} and a bounded Borel function f: \mathbbR₊ ? \mathbbR₊{f: \mathbb{R}_+ \to \mathbb{R}_+} , equivalent conditions for A and f(|T|) to be generalized absolute values of T are established and corresponding to them generalized absolute values of T* are determined.     

Nonautonomous stochastic search for global minimum in continuous optimization

Various iterative stochastic optimization schemes can be represented as discrete-time Markov processes defined by the nonautonomous equation _Xt+1=_Tt(_Xt,_Yt)$X_{t+1}=T_t(X_t,Y_t)$, where _Yt$Y_t$ is an independent sequence and _Tt$T_t$ is a sequence of mappings. This paper presents a general framework for the study of the stability and convergence of such optimization processes. Some applications are given: the mathematical convergence analysis of two optimization methods, the elitist evolution strategy (μ+λ)$(\mu +\lambda )$ and the grenade explosion method, is presented.     

Functor of extension in Hilbert cube and Hilbert space

It is shown that if Ω = Q or Ω = ? ₂, then there exists a functor of extension of maps between Z-sets in Ω to mappings of Ω into itself. This functor transforms homeomorphisms into homeomorphisms, thus giving a functorial setting to a well-known theorem of Anderson [Anderson R.D., On topological infinite deficiency, Michigan Math. J., 1967, 14, 365–383]. It also preserves convergence of sequences of mappings, both pointwise and uniform on compact sets, and supremum distances as well as uniform continuity, Lipschitz property, nonexpansiveness of maps in appropriate metrics.     

Effective Stimulation of the Biotechnological Potential of the Medicinal White Rot Fungus: Phellinus pini by Menadione-Mediated Oxidative Stress

The effect of menadione (MQ; 2-methyl-1,4-naphtoquinone), a superoxide-generating agent, on the natural biodegradation system in the medicinal white rot fungus Phellinus pini was determined. While measuring the activities of extracellular manganese-dependent peroxidase (MnP) and intracellular chitinase, it was found that the application of MQ (0.75 mM) distinctly stimulated the activities of these enzymes in comparison to the control values (without MQ). Using the capillary electrophoresis (CE) method, an increase in the extracellular oxalic acid (OXA) concentration was detected during the first days after the addition of MQ. It was observed that the rate of intracellular proteolysis at pH 3.5 evidently decreased under oxidative stress conditions. Contrary to these results, the activities of serine proteases at pH 9.5 measured against fluorogenic peptide substrates distinctly increased in stressed cultures. The MQ treatment also caused an evident increase in the catalase (CAT) activity, as well as the levels of superoxide anion radicals (SORs), formaldehyde (FA), and phenolic compounds (PHC) in the experimental cultures. The results obtained confirm that prooxidants may find application as an effective way to stimulate biotechnological production of MnP and chitinase by white rot fungi.     

Supramolecular Engineering of Cathode Materials for Aqueous Zinc-ion Energy Storage Devices: Novel Benzothiadiazole Functionalized Two-Dimensional Olefin-Linked COFs

Two-dimensional covalent organic frameworks (COFs) have emerged as promising materials for energy storage applications exhibiting enhanced electrochemical performance. While most of the reported organic cathode materials for zinc-ion batteries use carbonyl groups as electrochemically-active sites, their high hydrophilicity in aqueous electrolytes represents a critical drawback. Herein, we report a novel and structurally robust olefin-linked COF-TMT-BT synthesized via the aldol condensation between 2,4,6-trimethyl-1,3,5-triazine (TMT) and 4,4′-(benzothiadiazole-4,7-diyl)dibenzaldehyde (BT), where benzothiadiazole units are explored as novel electrochemically-active groups. Our COF-TMT-BT exhibits an outstanding Zn²⁺ storage capability, delivering a state-of-the-art capacity of 283.5 mAh g⁻¹ at 0.1 A g⁻¹. Computational and experimental analyses reveal that the charge-storage mechanism in COF-TMT-BT electrodes is based on the supramolecularly engineered and reversible Zn²⁺ coordination by the benzothiadiazole units.     

Self-assembling DNA-peptide hybrids: morphological consequences of oligonucleotide grafting to a pathogenic amyloid fibrils forming dipeptide

For the very first time, highly efficient synthesis of DNA-peptide hybrids to scaffold self-assembled nanostructures is described. Oligonucleotide conjugation to the diphenylalanine dipeptide triggers a morphological transition from fibrillar to vesicular structures which may potentially be used as delivery vehicles, since they exhibit pH triggered release.     

M?ssbauer studies of hemoglobin in erythrocytes exposed to neutron radiation

We studied radiation effects on the stability of various states of hemoglobin (Hb) in red blood cells (RBC) irradiated with a very low dose of neutron rays, 50?μGy. We investigated RBCs isolated from blood of healthy donors. M?ssbauer spectroscopy was applied to monitor different forms of Hb. Our results show, for the first time, that oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoxyHb) are two Hb forms sensitive to such a low neutron radiation. Both Hbs change into a new Hb form (Hb_irr). Additionally, OxyHb transfers into HbOH/H₂O, which under our experimental conditions is resistant to the action of neutron rays.     

Predictive tracking of an object by a pan–tilt camera of a robot

Nonlinear Dynamics - Moving-object tracking using a pan–tilt camera setup is quite a well-known task in robotics. However, the presented research addresses specific properties of the tracked...