Possible Impact of Heterogeneous Photocatalysis on the Global Chemistry of the Earth's Atmosphere

Photochemistry is recognized to be important for various physicochemical processes in the atmosphere, such as formation of the ozone layer and smogs, degradation of waste substances, etc. [1]. However, up to the present the emphasis in atmospheric photochemistry has been mainly on the study of photochemical reactions that occur with molecules directly excited by absorption of light quanta. However, the major components and impurities of the earth's atmosphere (such as nitrogen, oxygen, water, carbon dioxide, methane, methane halides, etc.) are totally transparent to most solar radiation. Electronically excited states of these molecules are formed only upon absorption of vacuum ultraviolet light quanta with energy hv ≥ 5 eV (i.e., with wavelength λ ≤ 200 nm). Only a small portion of the energy of solar light is found in this spectral region. In other words, most of the energy of the solar flux cannot participate in such direct photochemical reactions.     

Irreversibility and creativity in neurodynamics

This paper presents an approach to formalization of the concept of creativity in connection with the new architecture of neural networks based upon non-Lipschitzian dynamics. A new nonlinear phenomenon—terminal chaos caused by failure of the Lipschitz condition at equilibrium points of dynamical systems is introduced. It is shown that terminal chaos has a well-organized probabilistic structure which can be predicted and controlled. This gives an opportunity to exploit this phenomenon for information processing. It appears that chaotic states of neurons activity are associated with a higher level of cognitive processes such as generalization and abstraction. The relationship between creativity, irreversibility and unpredictability in neurodynamics are discussed. The theory is illustrated by examples.     

Investigation of the Electronic Structure of Y2Cu2O5–xSx(x — 0.0, 0.25, 0.75) by X-ray Emission Spectroscopy and Xα Scattered Wave Calculation Methods

The investigation of the electronic properties of various copper oxides, containing structural fragments with specific Cu-O polyhedra, has been carried out. The electronic structure of Y₂Cu₂O_5–xS_x compounds (x = 0.0, 0.25, 0.75) has been studied by X-ray emission spectroscopy and the X_α scattered wave (SW) method of calculation. It is shown that substituting apical oxygen by sulfur in the squarepyramid fragments in high-temperature superconductors will result in a decrease of the density of hole carriers in "superconducting" grids of CuO₂ and in the suppression of superconductivity .     

Analysis of the Transient and Steady-State Processes in the Parallel Inverter

This paper deals with the analysis of the transient and steady-state processes in parallel inverters. A set of difference equations, describing the currents and voltages during transient and steady state is obtained and solved. The solution is found in closed form. The roots of the characteristic equations are examined and possible types of transients are discussed. Theoretical and experimental results both for transient and steady-state conditions are compared and satisfactory agreements are found.     

Organic Bionics: A New Dimension in Neural Communications

The term “bionics” is synonymous with the term “biomimetics” and in this context refers to the integration of human engineered devices to take advantage of functional mechanisms and structures resident in nature. The use of electrical conductors to transmit charge into and out of biological systems to affect biological processes has been the source of great scientific interest. This has inspired many to explore the possible use of electrical stimulation in promoting positive health outcomes. Advances in medical bionics technology are dependent upon eliciting precise control of the electrical energy to deliver beneficial health outcomes. The advent of carbon‐based organic conductors now provides the platform for unprecedented possibilities by which the electrical energy can be used to modulate the function of medical devices. The use of organic conductors in the field of bionics, and in particular medical bionics, as that involved with the development of devices that enable the effective integration of biology (nature) and electronics to achieve a targeted functional outcome is explored.     

Cytogenetically Elusive Sex Chromosomes in Scincoidean Lizards

The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a remarkable ecological and morphological divergence. However, previous studies revealed limited variability in cytogenetic traits. The sex determination mode was revealed only in a handful of gerrhosaurid, skink, and xantusiid species, which demonstrated either ZZ/ZW or XX/XY sex chromosomes. In this study, we explored the karyotypes of six species of skinks, two species of cordylids, and one gerrhosaurid. We applied conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization with probes specific for telomeric motifs and rDNA loci, and comparative genomic hybridization. The diploid chromosome numbers are rather conserved among these species, but the chromosome morphology, the presence of interstitial telomeric sequences, and the topology of rDNA loci vary significantly. Notably, XX/XY sex chromosomes were identified only in Tiliqua scincoides, where, in contrast to the X chromosome, the Y chromosome lacks accumulations of rDNA loci. We confirm that within the lizards of the scincoidean clade, sex chromosomes remained in a generally poor stage of differentiation.     

Large and small signal distortion analysis using modified Volterra series

A new approach to the Volterra analysis of analog circuits is presented. Volterra analysis is widely used for the calculation of harmonic and intermodulation distortion products. However, the analysis is limited to circuits experiencing small signal excitations and becomes inaccurate when the input signal amplitude increases, especially when MOS transistors are involved. In this paper, we analyze the cause of this drawback, which is no other than the Taylor series’ convergence properties. Moreover, we propose a solution, by calculating the nonlinearity coefficients using a different type of polynomial expansion, the Chebyshev series. This replacement improves significantly the capabilities of Volterra analysis. We also present results comparing Chebyshev series with other types of polynomial expansions. Finally, we apply the proposed method to analyze the intermodulation distortion (IMD) of a CMOS RF power amplifier, both in the small and the large signal regimes.     

Diastereoselective Synthesis of Novel Spiro-Phosphacoumarins and Evaluation of Their Anti-Cancer Activity

Herein we present the regio- and diastereoselective synthesis of novel pyrrolidine-fused spiro-dihydrophosphacoumarins via intermolecular [3 + 2] cycloaddition reaction. The presented approach is complementary to existing ones and provides an easy entry to the otherwise inaccessible derivatives. Additionally, the unprecedented pathway of the reaction of 4-hydroxycoumarin with azomethine ylides is described. The anti-cancer activity of the obtained compounds was tested in vitro, the most potent compound being 2.6-fold more active against the HuTu 80 cell line than the reference 5-fluorouracil, with a selectivity index > 32.     

Effects of β-amyloid (1-42) Administration on the Main Neurogenic Niches of the Adult Brain: Amyloid-Induced Neurodegeneration Influences Neurogenesis

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and warrants further study as well as timely treatment. Additionally, the mechanisms of the brain’s intrinsic defense against chronic injury are not yet fully understood. Herein, we examined the response of the main neurogenic niches to amyloid exposure and the associated changes in structure and synaptic activity. Flow cytometry of Nestin-, Vimentin-, Nestin/Vimentin-, NeuN-, GFAP-, NeuN/GFAP-, NSE-, BrdU-, Wnt-, BrdU/Wnt-, VEGF-, Sox14-, VEGF/Sox14-, Sox10-, Sox2-, Sox10/Sox2-, Bax-, and Bcl-xL-positive cells was performed in the subventricular zone (SVZ), hippocampus, and cerebral cortex of rat brains on 90th day after intracerebroventricular (i.c.v.) single injection of a fraction of β-amyloid (Aβ) (1-42). The relative structural changes in these areas and disruptions to synaptic activity in the entorhinal cortex–hippocampus circuit were also evaluated. Our flow analyses revealed a reduction in the numbers of Nestin-, Vimentin-, and Nestin/Vimentin-positive cells in neurogenic niches and the olfactory bulb. These changes were accompanied by an increased number of BrdU-positive cells in the hippocampus and SVZ. The latter changes were strongly correlated with changes in the numbers of VEGF- and VEGF/Sox14-positive cells. The morphological changes were characterized by significant neural loss, a characteristic shift in entorhinal cortex–hippocampus circuit activity, and decreased spontaneous alternation in a behavioral test. We conclude that although an injection of Aβ (1-42) induced stem cell proliferation and triggered neurogenesis at a certain stage, this process was incomplete and led to neural stem cell immaturity. We propose the idea of enhancing adult neurogenesis as a promising strategy for preventing dementia at healthy elderly people andpeople at high risk for developing AD, or treating patients diagnosed with AD.