Entanglement in photo-ionization process.

We report a study of the entanglement between the quantized photon field and an atom arising in the photo-ionization process. Our approach is based on an ab initio solution of the time-dependent Schrödinger equation (TDSE) describing the quantum evolution of a bipartite system consisting of the atom and the quantized electromagnetic field. Using the solution of the TDSE, we calculate the reduced photon density matrix, which we subsequently use to compute entanglement entropy. We explain some properties of the entanglement entropy and propose an approximate formula for the entanglement entropy based on the analysis of the density matrix and its eigenvalues. We present the results of a comparative study of the entanglement in the photo-ionization process for various ionization regimes, including the tunneling and the multiphoton ionization regimes.

Joint probability calculation of the lateral velocity distribution in strong field ionization process.

We describe an approach to the description of the time-development of the process of strong field ionization of atoms based on the calculation of the joint probability of occurrence of two events, event B being finding atom in the ionized state after the end of the laser pulse, event A being finding a particular value of a given physical observable at a moment of time inside the laser pulse duration. As an example of such an physical observable we consider lateral velocity component of the electron's velocity. Our approach allows us to study time-evolution of the lateral velocity distribution for the ionized electron during the interval of the laser pulse duration. We present results of such a study for the cases of target atomic systems with short range Yukawa and Coulomb interactions.

Interference patterns in ionization of Kramers-Henneberger atom.

We combine IR pump and XUV probe laser pulses to visualize the Kramers-Henneberger (KH) state of the potassium atom. We demonstrate that ionization of such an atom exhibits some molecular-like features such as low order interference maxima in photoelectron momentum spectra. The locations of these maxima allow to estimate spatial dimensions of the KH atom and can be used for accurate calibration of high intensity laser fields. At the same time, we show that an analogy between the KH atom and a homo-nuclear diatomic molecule cannot be extended too far. In particular, higher order interference maxima are very difficult to observe in the case of the KH state. We attribute this to a particular structure of the KH potential which does not confine electron motion to a well-defined potential well unlike in real diatomic molecules.

Synthetic Analogs of 6-Bromohypaphorine, a Natural Agonist of Nicotinic Acetylcholine Receptors, Reduce Cardiac Reperfusion Injury in a Rat Model of Myocardial Ischemia.

The data available to date indicate that the activation of nicotinic acetylcholine receptors (nAChR) of α7 type can reduce heart damage resulting from ischemia and subsequent reperfusion. We have studied two new synthetic D-analogs of 6-bromohypaphorine, which are selective agonists of α7 nAChR, in a rat model of myocardial ischemia. Acute myocardial infarction in animals was induced by occlusion of the left coronary artery with its subsequent reperfusion under mechanical lung ventilation. It was found that one of the analogs was more active, and treatment with it at the onset of reperfusion statistically reduced infarct size. This analog also prevented changes in the concentration of potassium and sodium ions in the blood, occurring during occlusion/reperfusion injury. The data obtained indicate that hypaphorine analogs are promising for the development of drugs that reduce the adverse effects of myocardial infarction.

Effect of the finite speed of light in ionization of extended molecular systems.

We study propagation effects due to the finite speed of light in ionization of extended molecular systems. We present a general quantitative theory of these effects and show under which conditions such effects should appear. The finite speed of light propagation effects are encoded in the non-dipole terms of the time-dependent Shrödinger equation and display themselves in the photoelectron momentum distribution projected on the molecular axis. Our numerical modeling for the [Formula: see text] molecular ion and the [Formula: see text] dimer shows that the finite light propagation time from one atomic center to another can be accurately determined in a table top laser experiment which is much more readily accessible than the ground breaking synchrotron measurement by Grundmann et al. (Science 370:339, 2020).

Distribution of absorbed photons in the tunneling ionization process.

We describe a procedure that allows us to solve the three-dimensional time-dependent Schrödinger equation for an atom interacting with a quantized one-mode electromagnetic field. Atom-field interaction is treated in an ab initio way prescribed by quantum electrodynamics. We use the procedure to calculate probability distributions of absorbed photons in the regime of tunneling ionization. We analyze evolution of the reduced photon density matrix describing the state of the field. We show that non-diagonal density matrix elements decay quickly, as a result of the decoherence process. A stochastic model, viewing ionization as a Markovian birth-death process, reproduces the main features of the calculated photon distributions.

Dimeric Disintegrins from the Steppe Viper V. ursinii Venom.

Four dimeric disintegrins were isolated from the venom of the steppe viper V. ursinii using liquid chromatography. Disintegrins prevented adhesion of MCF7 cells to fibronectin, which indicates their interaction with integrin receptors of the αVß1 type. According to mass spectrometry data, the molar masses of disintegrins are about 14 kDa. The method of peptide mapping established the structure of a new heterodimeric disintegrin weighing 13 995.5 Da and shows that it belongs to the class of RGD/KGD-containing disintegrins.

Study of irradiation effect of Xe+22 and Kr+14 ions on structural properties of Zn nanotubes.

The paper presents the results of synthesis and directed modification of structural properties of Zn nanotubes by irradiating with heavy ions. The nanotubes were obtained by electrochemical deposition in pores of template polymer matrices. It was established using SEM, XRD and EDS methods where irradiation with Xe+22 and Kr+14 ions makes it possible to modify the crystal structure of nanotubes. As a result of irradiation with Xe+22 ions, partial destruction of nanotubes is observed, which indicates an increase in the number of defects in the structure and a decrease in strength properties. Change in the crystal structure parameters is observed when irradiation with Kr+14 ions with fluence below 5 × 1011 ion cm-2. That indicates the possibility of using Kr+14 ions for directional modification of nanostructures, while irradiation with Xe+22 ions leads to amorphization and destruction of nanotubes.

Polyarginine Peptides As a New Class of Ligands of Nicotinic Acetylcholine Receptors.

Arginine-containing peptides R3, R8, and R16 were obtained by solid-phase peptide synthesis, and their binding to nicotinic acetylcholine receptors (nAChRs) of muscle and neuronal (α7) types was studied by competitive radioligand assay with the use of 125I-α-bungarotoxin. The resulting peptides exhibited a significantly greater binding activity with respect to the muscle-type nAChRs than to the α7 receptor. Thus, we have discovered a new class of nAChR ligands. The affinity of the synthesized oligoarginines for nAChR depended on the number of amino acid residues in the chain. The highest affinity was exhibited by the R16 peptide, which contained 16 arginine residues.

Low-molecular-weight compounds with anticoagulant activity from the scorpion Heterometrus laoticus venom.

Low-molecular-weight compounds with anticoagulant activity were isolated from the scorpion Heterometrus laoticus venom. The determination of the structure of the isolated compounds by nuclear magnetic resonance and mass spectrometry showed that one of the isolated compounds is adenosine, and the other two are dipeptides leucyl-tryptophan and isoleucyl-tryptophan. The anticoagulant properties of adenosine, which is an inhibitor of platelet aggregation, is well known, but its presence in scorpion venom is shown for the first time. The ability of leucyl-tryptophan and isoleucyl-tryptophan to slow down blood clotting and their presence in scorpion venom are also established for the first time.

Arginine derivatives of dicarboxylic acids from the parotid gland secretions of common toad Bufo bufo-New agonists of ionotropic γ-aminobutyric acid receptors.

Compounds activating γ-aminobutyric acid type A receptor were isolated from the toad Bufo bufo venom as a result of chromatographic separation. Analysis of the structure of these compounds by mass spectrometry and nuclear magnetic resonance showed that they are arginine derivatives of dicarboxylic acids and represent suberylarginine, pimeloylarginine, and adipoylarginine.

N-methyl serotonin analogues from the Bufo bufo toad venom interact efficiently with the α7 nicotinic acetylcholine receptors.

Two low-molecular-weight compounds were isolated from the parotid gland secret of the toad Bufo bufo, which by absorption spectra and HPLC-MS/MS chromatography data correspond to di- and trimethyl derivatives of serotonin (5-hydorxytryptamine): bufotenine (confirmed by counter synthesis) and bufotenidine (5-HTQ). In experiments on competitive radioligand binding, these compounds showed a higher affinity and selectivity for neuronal α7 nicotinic acetylcholine receptors compared with the muscular cholinergic receptors. The most efficient compound in terms of binding value was bufotenine, the efficiency of 5-HTQ was an order of magnitude lower, and the minimal activity was exhibited by serotonin.

Exit point in the strong field ionization process.

We analyze the process of strong field ionization using the Bohmian approach. This allows retention of the concept of electron trajectories. We consider the tunnelling regime of ionization. We show that, in this regime, the coordinate distribution for the ionized electron has peaks near the points in space that can be interpreted as exit points. The interval of time during which ionization occurs is marked by a quick broadening of the coordinate distribution. The concept of the exit point in the tunneling regime, which has long been assumed for the description of strong field ionization, is justified by our analysis.

Analysis of binding centers in nicotinic receptors with the aid of synthetic peptides.

We studies the receptor-binding specificity of the synthetic peptide HAP (High Affinity Peptide) and its analogues, which are regarded as a model of the orthosteric site nicotinic acetylcholine receptors (nAChR). Using radioligand analysis, electrophysiology tests, and calcium imaging, we assessed the ability of HAP to interact with nAChR antagonists: long α-neurotoxins and α-conotoxins. A high affinity of HAP for α-bungarotoxin and the absence of its interaction with α-cobratoxin and α-conotoxins was found. The synthesized analogues of HAP in general retained the properties of the original peptide. Thus, HAP cannot be a model of a ligand-binding site.

Transverse electron momentum distribution in tunneling and over the barrier ionization by laser pulses with varying ellipticity.

We study transverse electron momentum distribution in strong field atomic ionization driven by laser pulses with varying ellipticity. We show, both experimentally and theoretically, that the transverse electron momentum distribution in the tunneling and over the barrier ionization regimes evolves in a qualitatively different way when the ellipticity parameter describing polarization state of the driving laser pulse increases.

Characterization of biocenoses in the storage reservoirs of liquid radioactive wastes of Mayak PA. Initial descriptive report.

As a result of operation of the Mayak Production Association (Mayak PA), Chelyabinsk Oblast, Russia, an enterprise for production and separation of weapon-grade plutonium in the Soviet Union, ecosystems of a number of water bodies have been radioactively contaminated. The article presents information about the current state of ecosystems of 6 special industrial storage reservoirs of liquid radioactive waste from Mayak PA: reservoirs R-3, R-4, R-9, R-10, R-11 and R-17. At present the excess of the radionuclide content in the water of the studied reservoirs and comparison reservoirs (Shershnyovskoye and Beloyarskoye reservoirs) is 9 orders of magnitude for (90)Sr and (137)Cs, and 6 orders of magnitude for alpha-emitting radionuclides. According to the level of radioactive contamination, the reservoirs of the Mayak PA could be arranged in the ascending order as follows: R-11, R-10, R-4, R-3, R-17 and R-9. In 2007-2012 research of the status of the biocenoses of these reservoirs in terms of phytoplankton, zooplankton, bacterioplankton, zoobenthos, aquatic plants, ichthyofauna, avifauna parameters was performed. The conducted studies revealed decrease in species diversity in reservoirs with the highest levels of radioactive and chemical contamination. This article is an initial descriptive report on the status of the biocenoses of radioactively contaminated reservoirs of the Mayak PA, and is the first article in a series of publications devoted to the studies of the reaction of biocenoses of the fresh-water reservoirs of the Mayak PA to a combination of natural and man-made factors, including chronic radiation exposure.

[Proton Transfer Reaction Mass Spectrometry of Exhaled Breath in Diagnostics of Heart Failure].

BACKGROUND: Exhaled breath analysis is one of directions in the search for novel biomarkers of chronic heart failure (CHF). According.

Investigation of thermo-optical characteristics of magneto-active crystal Na(0.37)Tb(0.63)F(2.26).

Thermo-optical characteristics of a new magneto-active material, Na(0.37)Tb(0.63)F(2.26) crystal, were investigated in this Letter. This crystal has a high value of magneto-optical figure-of-merit and negative optical anisotropy parameter that makes it a promising material for development of Faraday isolators for high-power lasers; in particular it gives opportunities for the realization of new schemes of optical isolators.

α-conotoxins revealed different roles of nicotinic cholinergic receptor subtypes in oncogenesis of Ehrlich tumor and in the associated inflammation.

Multiple injections of conotoxin MII, a blocker of alfa3-ß2 and alfa6-containing subtypes of nicotinic acetylcholine receptors (n-AChRs), as well as conotoxin ArIB11L16D, a blocker of alfa7 subtype n-AChR, at a dose of 1 nmol/kg reduce both the lactate dehydrogenase level in tumor cells and the inflammatory leukocyte infiltration in tumor tissue in mice bearing Ehrlich carcinoma. The first stage of pathomorphism was detected in the tumor tissue after the treatment with the ArIB11L16D conotoxin, whereas the second stage was observed after the treatment with conotoxins RgIA and MII. Only MII injections led to a significant reduction in tumor growth. Our results show the involvement of n-AChRs in the regulation of metabolic processes and cell-cell interactions related to carcinogenesis and tumor-associated inflammation.