The pre-exponential voltage-exponent as a sensitive test parameter for field emission theories.

For field electron emission (FE), an empirical equation for measured current I m as a function of measured voltage V m has the form I m = CV m k exp[-B/V m], where B is a constant and C and k are constants or vary weakly with V m. Values for k can be extracted (i) from simulations based on some specific FE theory, and in principle (ii) from current-voltage measurements of sufficiently high quality. This paper shows that a comparison of theoretically derived and experimentally derived k-values could provide a sensitive and useful tool for comparing FE theory and experiment, and for choosing between alternative theories. Existing methods of extracting k-values from experimental or simulated current-voltage data are discussed, including a modernized 'least residual' method, and existing knowledge concerning k-values is summarized. Exploratory simulations are reported. Where an analytical result for k is independently known, this value is reliably extracted. More generally, extracted k-values are sensitive to details of the emission theory used, but also depend on assumed emitter shape; these two influences will need to be disentangled by future research, and a range of emitter shapes will need examination. Other procedural conclusions are reported. Some scientific issues that this new tool may eventually be able to help investigate are indicated.

[Effect of benzo(a)pyrene on the expression of AhR-regulated microRNA in female and male rat lungs]. / Vliianie benz[a]pirena na ékspressiiu AhR-reguliruemykh mikroRNK v legkikh samok i samtsov krys.

Smoking is the main risk factor for lung cancer, mainly due to presence of nitrosamines and polycyclic aromatic hydrocarbons, including benzo[a]pyrene (BP) in tobacco smoke composition. The genotoxic effect of BP is based on the high DNA-binding ability of its metabolites, while the epigenetic effects are mediated by a change in the expression of cancer related genes or regulatory RNAs. It has been shown that women have a higher risk to develop lung cancer upon smoking rather than men. We hypothesized that crosstalk between signaling pathways activated by BP and estrogens could underlie the sex-dependent differences in miRNAs expression. To test this hypothesis, male and female rats were subjected to short-term or long-term BP exposure. Using in silico analysis, miRNAs containing the ER- and AhR-binding sites in the promoters of the genes (or host genes) were selected. During chronic exposure of BP the expression of miR-22-3p, -29a-3p, -126a-3p, -193b-5p in the lungs of male rats were significantly increased, while the level of miRNA-483-3p were decreased. Expression of miRNA-483-3p was up-regulated during chronic BP exposure in the lungs of female rats and the levels of other studied miRNAs were unchanged. In turn, changes in the expression of miRNAs were followed by changes in the expression of their target genes, including PTEN, EMP2, IGF1, ITGA6, SLC34A2, and the observed changes in female and male rat lungs were varied. Thus, our results suggest that sex-dependent epigenetic effects of BP may be based on different expression of AhR- and ER- regulated miRNAs.

Machine Learning Non-Markovian Quantum Dynamics.

Machine learning methods have proved to be useful for the recognition of patterns in statistical data. The measurement outcomes are intrinsically random in quantum physics, however, they do have a pattern when the measurements are performed successively on an open quantum system. This pattern is due to the system-environment interaction and contains information about the relaxation rates as well as non-Markovian memory effects. Here we develop a method to extract the information about the unknown environment from a series of projective single-shot measurements on the system (without resorting to the process tomography). The method is based on embedding the non-Markovian system dynamics into a Markovian dynamics of the system and the effective reservoir of finite dimension. The generator of Markovian embedding is learned by the maximum likelihood estimation. We verify the method by comparing its prediction with an exactly solvable non-Markovian dynamics. The developed algorithm to learn unknown quantum environments enables one to efficiently control and manipulate quantum systems.

Effect of Benzo(a)pyrene on the Expression of miR-483-3p in Hepatocyte Primary Culture and Rat Liver.

Here, we suggested that the epigenetic mechanism of benzo(a)pyrene (BP) action might be based on the aryl hydrocarbon receptor (AhR)-mediated transcription of the target genes, including miRNAs, that have the dioxin response element (DRE) in their promoters. The effect of BP on the expression of the oncogenic miR-483-3p, its host gene IGF2, and target gene IGF1 in primary hepatocytes and in the liver of Wistar female rats was investigated. The activation of AhR was confirmed using selective AhR inhibitor CH-223191 and by evaluating expression of the target CYP1A1 gene. The lack of coordination between the expression of miR-483-3p and its host gene IGF2 was revealed, which may be due to the presence of the binding site for the estrogen receptor alpha (ERα), which is a negative expression regulator. Our results confirm the existence of the AhR-mediated pathway in the regulation of expression of miR-483-3p, IGF1, and IGF2 under BP exposure, which is of considerable interest for understanding the epigenetic mechanisms of the carcinogenic effect of BP.

Simulation Complexity of Open Quantum Dynamics: Connection with Tensor Networks.

The difficulty to simulate the dynamics of open quantum systems resides in their coupling to many-body reservoirs with exponentially large Hilbert space. Applying a tensor network approach in the time domain, we demonstrate that effective small reservoirs can be defined and used for modeling open quantum dynamics. The key element of our technique is the timeline reservoir network (TRN), which contains all the information on the reservoir's characteristics, in particular, the memory effects timescale. The TRN has a one-dimensional tensor network structure, which can be effectively approximated in full analogy with the matrix product approximation of spin-chain states. We derive the sufficient bond dimension in the approximated TRN with a reduced set of physical parameters: coupling strength, reservoir correlation time, minimal timescale, and the system's number of degrees of freedom interacting with the environment. The bond dimension can be viewed as a measure of the open dynamics complexity. Simulation is based on the semigroup dynamics of the system and effective reservoir of finite dimension. We provide an illustrative example showing the scope for new numerical and machine learning-based methods for open quantum systems.

Supramolecular structures and self-association processes in polymer systems.

Self-organization in a polymer system appears when a balance is achieved between long-range repulsive and short-range attractive forces between the chemically different building blocks. Block copolymers forming supramolecular assemblies in aqueous media represent materials which are extremely useful for the construction of drug delivery systems especially for cancer applications. Such formulations suppress unwanted physicochemical properties of the encapsulated drugs, modify biodistribution of the drugs towards targeted delivery into tissue of interest and allow triggered release of the active cargo. In this review, we focus on general principles of polymer selforganization in solution, phase separation in polymer systems (driven by external stimuli, especially by changes in temperature, pH, solvent change and light) and on effects of copolymer architecture on the self-assembly process.

Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires.

Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (∼50-130 µeV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications.

Micelle-forming HPMA copolymer conjugates of ritonavir bound via a pH-sensitive spacer with improved cellular uptake designed for enhanced tumor accumulation.

We describe design, synthesis, physico-chemical characterization and preliminary biological evaluation of micelle-forming polymer drug conjugates with controlled drug release intended for tumor treatment. The structure of the conjugates was designed to enable tumor tissue- and cell-specific drug release and micelle disassembly to avoid side effects accompanying classic chemotherapy and guarantee safe elimination of the drug-free carrier from the organisms. The amphiphilic polymer conjugates consisted of a hydrophobic hexaleucine block and a hydrophilic block based on the N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer with an antiviral and cytostatic drug, ritonavir, bound through a pH-sensitive spacer. Diblock copolymers with low dispersity (D∼ 1.1) were prepared via reversible addition-fragmentation chain transfer (RAFT) copolymerization using a hexaleucine derivative as a chain transfer agent. The associative properties of the copolymers depend on the hydrophilic polymer block length and the hydrophobic ritonavir content. The micelles dissociated under mild acidic conditions mimicking the environment inside tumor tissue/cells, because of the decrease in polymer hydrophobicity after the rapid release of the hydrophobic drug from the polymer carrier. Unexpectedly, the polymer-ritonavir conjugates internalized into HeLa cells significantly more than the polymers without ritonavir. The enhanced cell penetration and pH-triggered micelle disassembly predetermine the polymer-ritonavir conjugates to become promising tumor-targeted drug carriers.

[Efficiency of succinic acid infusion solutions in minor surgery].

A group of 66 patients with purulent-septic surgical pathology on the background of type 2 diabetes mellitus (in the compensation phase) and atherosclerosis of vessels in lower extremities (in the decompensation phase) have been studied. The status of all patients has been determined by the syndrome of systemic inflammation reaction (rated 12.4 +/- 2.2 on the APACHE II scale). Group I (n = 30) included 19 men aged 53.7 +/-7.7 and 11 women aged 54.4 +/- 9.1, which were administered reamberin (single daily dose of 500 ml for three days after operation). Group II (n = 36) included 24 men aged 56.1 +/- 9.2 and 12 women aged 51.9 +/- 8.8 with analogous pathology and general status, which received infusion therapy without reamberin. It is established that the administration of reamberin in patients with purulent-septic surgical pathology on the background of type 2 diabetes mellitus and atherosclerosis of vessels in lower extremities is patho-. genetically justified and allows the reperfusion syndrome upon various operations to be prevented and the critical state in post-operation regime to be eliminated.

Defect properties of ZnO nanowires revealed from an optically detected magnetic resonance study.

Optically detected magnetic resonance (ODMR) complemented by photoluminescence measurements is used to evaluate optical and defect properties of ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition. By monitoring visible emissions, several grown-in defects are revealed and attributed to Zn vacancies, shallow (but not effective mass) donor and exchange-coupled pairs of Zn vacancies and Zn interstitials. It is also found that the intensity of the donor-related ODMR signals is substantially lower in the NWs compared with that in bulk ZnO. This may indicate that formation of native donors is suppressed in NWs, which is beneficial for achieving p-type conductivity.

Evidence for coupling between exciton emissions and surface plasmon in Ni-coated ZnO nanowires.

We show that coating ZnO nanowires (NWs) with a transition metal, such as Ni, can increase the efficiency of light emission at room temperature. Based on detailed structural and optical studies, this enhancement is attributed to energy transfer between near-band-edge emission in ZnO and surface plasmons in the Ni film which leads to an increased rate of the spontaneous emission. It is also shown that the Ni coating leads to an enhanced non-radiative recombination via surface states, which becomes increasingly important at low measurement temperatures and in annealed ZnO/Ni NWs.

Molecular properties of hybrid macromolecular antioxidants: dextran hydrophobically modified by sterically hindered phenols.

The conformation properties of clinically relevant hybrid macromolecular antioxidants (dextran hydrophobically modified by sterically hindered phenols) in aqueous solution were characterized by a combination of dynamic light scattering (DLS), size exclusion chromatography (SEC), and small-angle neutron scattering (SANS). We were able to split and analyze separately two different types of polydispersity -polydispersity over molecular weights and the one over substitution degree. The properties of the hybrid macromolecules are determined by the number of hydrophobic antioxidants in a single molecule. An insertion of hydrophobic groups into a hydrophilic chain changes the conformation of a single conjugate macromolecule. We have established that with the increasing of a number of hydrophobic antioxidant groups, a conformational transition occurs where a single conjugate undergoes a transition from a Gaussian coil conformation to a more compact structure.

Expression of melatonin and serotonin in human prostate tumors.

We present the results of immunohistochemical study demonstrating possible variants of neuroimmunoendocrine regulation of prostate tumor growth with serotonin, melatonin, and other hormones produced by neuroendocrine cells via paracrine and autocrine secretory mechanisms.

[Clinical and neuroimmunoendocrine effects of doxasosine in treatment of benign hyperplasia of the prostate in elderly people].

Benign hyperplasia of prostate is a very important not only medical but also social problem. The clinical and neuroimmunoendocrine status of elderly patients with benign hyperplasia of prostate treated by 1-blocker doxasosine is described in this article. Intercellular interactions were examined for tumor necrosis factor a (TNF-alpha), proinflammative interleukine-6 (IL-6), soluble intercellular molecule of adhesion (sICAM). The positive role of doxasosine is demonstrated.

[Clinical and neuroimmunoendocrine effects of doxasosine in treatment of arterial hypertension accompanied by prostate benign hyperplasia in elderly people].

Arterial hypertension accompanied by prostate benign hyperplasia is very important not medical but social problem in elderly people. The clinical and neuroimmunoendocrine status of elderly patients with arterial hypertension accompanied by prostate benign hyperplasia treated by alpha1-blocker doxasosine is described in the article. Intercellular interactions were examined for tumor necrosis factor alpha, proinflammative interleukine-6, soluble intersellular molecule of adhesion. The positive role of doxasosine is demonstrated.

[Medical and social problems in gerontology and geriatrics: the acknowledgment of patients and medical personnel].

The positions of patients and medical personnel are described in this article. The problems of prevention in elders and medical education of patients are investigated.

[Effect of the arginine and its metabolites on the rat myocardium in organothypic tissue culture in young and old rats].

The arginine and its metabolites were used to investigate the effect on organotypic tissue culture of explants from the spleen, liver, brain cortex and heart of young (3-month old) and aged (18-month old) rats. The arginine effective concentration was 0.5 ng/ml, showed proliferative effect in spleen, liver tissue cultures as compared to the control explants in both groups of rats. No effect of arginine was observed in nervous tissue culture in both groups of rats. The arginine and its metabolites--citrulline, ornitine, urea--stimulate the cell proliferation in miocardium explants in young rats, but not in old. The nitric oxid inhibits the heart explants in young rats.

Effect of amino acids and antibodies against nerve growth factor receptors on the development of organotypic culture of lymphoid tissue.

We studied the effects of 20 L-amino acids on organotypic culture of splenic lymphoid tissue from 3-month-old rats were studied in the presence of apoptosis-inducing monoclonal antibodies against low-affinity receptors for nerve growth factor NGFRp75. The influence of amino acids stimulating cell proliferation in explants (lysine, asparagine, and glutamic acid) did not depend on NGFRp75. Hydrophobic amino acids inhibiting the growth zone in isolated application and abolished the inhibition of explant development in the presence of antibodies against NGFRp75. These amino acids can mediate the proapoptotic effect on lymphoid tissue via low-affinity receptors for nerve growth factor.