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The nonenzymatic isoprostane pathway of lipid peroxidation of polyunsaturated fatty acids results in formation of products, termed isoprostanes, which have very large positional and stereo isomerism, possess various biological activities, produce adducts with proteins, and thus contribute to pathogeneses of the agedependent diseases. However, it was unclear what mechanism drives this type of lipid autoxidation, and why the products have very large isomerism. We propose a mechanism when perhydroxyl radicals (HO2•) react with polyunsaturated fatty acids in the hydrophobic milieu of membranes. In the membrane HO2• initiates a chain of reactions with formation first H2O2, which undergoes homolytic fission producing two •OH radicals, thus very rapidly abstracting three H atoms from a polyunsaturated fatty acid. As a result, the HO2• molecule is converted to two molecules of water, and the molecule of a polyunsaturated fatty acid loses two double bonds, becomes highly unstable and undergoes peroxidation and random intramolecular re-arrangements causing a very large isomerism of the final products. The extremely high reactivity of •HО2 with polyunsaturated fatty acids is the cause of very subtle and slow accumulation of damages in the membrane and membrane associated proteins, even though the concentration of •HО2 relative to superoxide radical may be very low.

For 38 pairs of the isomeric derivatives of maleimide and itaconimide, the Gibbs free energies were calculated using the density functional theory (DFT) and domain-based local pair natural orbital (DLPNO) methods. The effects of the solvent and of substituents in positions 1, 3, and 4 of the maleimide ring on the energy difference of the isomers were studied. Depending on the substituents and conditions, the equilibrium can shift toward the maleimide or itaconimide form. Further migration of the double bond and cis-trans -isomerism were also considered wherever possible.

The review covers publications over the past decade on new methods of synthesis of pyrrolo[3,4- b ]­pyrrole-4,6(1 H ,5 H )-diones, 4 H -thieno[2,3- c ]pyrrole-4,6(5 H )-diones, 4 H -pyrrolo[3,4- d ][1,3]thiazole-4,6(5 H )-di­ones, 5 H -pyrrolo[3,4- b ]pyridine-5,7(6 H )-diones, 1 H -pyrrolo[3,4- c ]pyridine-1,3(2 H )-diones, and other male­imide-fused heterocycles. Both methods for the construction of maleimide ring and those based on reactions of N-substituted maleimides, 3,4-dihalomaleimides, and other maleimide derivatives are considered.

High-energy cosmic rays The ATIC (Advanced Thin Ionizaton Calorimeter) cosmic-ray astronomy experiment sends helium balloons to altitudes of 35 km and more above Antarctica for up to 15 days at a time. These forays to the edge of space have resulted in the detection of an excess of Galactic cosmic-ray electrons at energies of around 300–800 GeV, which indicates a nearby source of energetic electrons. The source could be an unseen astrophysical object that accelerates electrons to those energies, or the electrons could arise from the annihilation of 'Kaluza-Klein' dark matter, an exotic concept predicted by theories of the Universe involving compactified extra dimensions. This paper reports an excess of galactic cosmic-ray electrons at energies of ∼300-800 GeV, which indicates a nearby source of energetic electrons. Such a source could be an unseen astrophysical object that accelerates electrons to those energies, or the electrons could arise from the annihilation of dark matter. Galactic cosmic rays consist of protons, electrons and ions, most of which are believed to be accelerated to relativistic speeds in supernova remnants 1 , 2 , 3 . All components of the cosmic rays show an intensity that decreases as a power law with increasing energy (for example as E -2.7 ). Electrons in particular lose energy rapidly through synchrotron and inverse Compton processes, resulting in a relatively short lifetime (about 10 5  years) and a rapidly falling intensity, which raises the possibility of seeing the contribution from individual nearby sources (less than one kiloparsec away) 4 . Here we report an excess of galactic cosmic-ray electrons at energies of ∼300–800 GeV, which indicates a nearby source of energetic electrons. Such a source could be an unseen astrophysical object (such as a pulsar 5 or micro-quasar 6 ) that accelerates electrons to those energies, or the electrons could arise from the annihilation of dark matter particles (such as a Kaluza–Klein particle 7 with a mass of about 620 GeV).

Recently, researchers demonstrated numerous types of the metasurfaces with non-radiating states including the anapole ones. These metasurfaces have promising properties for various applications in optics which are mainly connected with the optical field confinement. But by itself, the existence of the anapole state does not make one available to exploit this feature. For example, Ospanova et al. [16] presented a grouped nanohole array in silicon slab possessing anapole mode in visible range. In this work, it is proved that despite of the existence of the anapole mode in the proposed nanostructure the valuable electric field confinement is not reached. Thus most expected uses of the anapole state cannot be gained through this nanostructure. As demonstrated here, the aforementioned nanostructure may be replaced by the square nanohole array having the anapole state with different meta-atom and much larger electric field confinement.

The energies of enol and keto forms for 36 3-hydroxymaleimide derivatives have been calculated by the DFT and DLPNO methods. The results clearly show that, with only a few exceptions, the enol form is energetically more favorable by 16–60 kJ mol –1 , and the energy difference depends on the substituent in the 4-position. Global electrophilic index has been calculated for all the compounds, which demonstrates that the keto form is generally more electrophilic, and electrophilicity depends on the substituent in the 4-position. Two possible structures of hydroxymaleimide anion have been evaluated; the deprotonation of the oxygen atom turns out to be the most energetically favorable.

Siberia is one of few continental regions in the Northern Hemisphere where the atmosphere may sometimes approach pristine background conditions. We present the time series of aerosol and carbon monoxide (CO) measurements between September 2006 and December 2011 at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E). We investigate the seasonal, weekly and diurnal variations of aerosol properties (including absorption and scattering coefficients and derived parameters, such as equivalent black carbon (BCe), Ångström exponent, single scattering albedo, and backscattering ratio) and the CO mixing ratios. Criteria were established to distinguish polluted from near-pristine air masses, providing quantitative characteristics for each type. Depending on the season, 23–36% of the sampling time at ZOTTO was found to be representative of a clean atmosphere. The summer pristine data indicate that primary biogenic and secondary organic aerosol formation are quite strong particle sources in the Siberian taiga. The summer seasons 2007–2008 were dominated by an Aitken mode around 80 nm size, whereas the summer 2009 with prevailing easterly winds produced particles in the accumulation mode around 200 nm size. We found these differences to be mainly related to air temperature, through its effect on the production rates of biogenic volatile organic compounds (VOC) precursor gases. In winter, the particle size distribution peaked at 160 nm, and the footprint of clean background air was characteristic for aged particles from anthropogenic sources at great distances from ZOTTO and diluted biofuel burning emissions from domestic heating. The wintertime polluted air originates mainly from large cities south and southwest of the site; these particles have a dominant mode around 100 nm, and the ΔBCe / ΔCO ratio of 7–11 ng m−3 ppb−1 suggests dominant contributions from coal and biofuel burning for heating. During summer, anthropogenic emissions are the dominant contributor to the pollution particles at ZOTTO, while only 12% of the polluted events are classified as biomass-burning-dominated, but then often associated with extremely high CO concentrations and aerosol absorption coefficients. Two biomass-burning case studies revealed different ΔBCe / ΔCO ratios from different fire types, with the agricultural fires in April~2008 yielding a very high ratio of 21 ng m−3 ppb−1. Overall, we find that anthropogenic sources dominate the aerosol population at ZOTTO most of the time, even during nominally clean episodes in winter, and that near-pristine conditions are encountered only in the growing season and then only episodically.

The cause of Parkinson's disease (PD) is unknown, but epidemiological studies suggest an association with pesticides and other environmental toxins, and biochemical studies implicate a systemic defect in mitochondrial complex I. We report that chronic, systemic inhibition of complex I by the lipophilic pesticide, rotenone, causes highly selective nigrostriatal dopaminergic degeneration that is associated behaviorally with hypokinesia and rigidity. Nigral neurons in rotenone-treated rats accumulate fibrillar cytoplasmic inclusions that contain ubiquitin and α-synuclein. These results indicate that chronic exposure to a common pesticide can reproduce the anatomical, neurochemical, behavioral and neuropathological features of PD.

Correct techniques of and approaches to the analysis of production stability and measuring systems and management of products quality are significant for the tasks of development and improvement of a mechanical engineering enterprise quality control system. More opportunities arise for production quality managers enabling their dealing with claims and defects, elaboration of corrective actions and application of statistical methods for the analysis of quality of products. In this article, a technique for the analysis of defects of mechanical engineering products based on the system approach is suggested, and an example of its practical application is described. The main distinctive feature of the suggested technique consists in a description of each part or component of an assembly or a unit in the form of formulas offered at one of the stages. Application of the technique for the analysis of defects allows systematizing data on potential defects, probable causes and possible consequences of them, thus that leading to improvement of the management process and quality of products of mechanical engineering.

The characteristics of the ichthyofauna biodiversity of the Padma River (Ganges) in Bangladesh in the area of the Rooppur Nuclear Power Plant (NPP) is presented based on the research within the framework of the established in 2014–2017 network of ecological monitoring of aquatic ecosystems. In the Padma, 65 fish species from 12 orders and 22 families have been identified. The most representative order of the ichthyofauna is the catfishes (Siluriformes), which include 22 species from six families. The second largest order is Cypriniformes, with 16 species from the family Cyprinidae. The ichthyofauna of the Padma River has been studied in different periods of the year, considering the climatic features of the region. During the monsoon season, during the flood of the river, the taxonomic composition of fish increases up to 51 species, while in the low-water period it decreases to 29. The lowest number of species was recorded in the dry periods of the year (23–26 species). The average weight of the studied fish species varies from 0.7 ± 0.5 to 1053 ± 689 g, and the length varies from 4.0 ± 0.9 to 45.5 ± 14.1 cm. In the studied section of the river, we recorded 17 rare and minor fish species, included in the Red Data Book of Bangladesh. The importance of controlling the biodiversity of the ichthyofauna of the Padma River as an integral part of the environmental monitoring system for the Rooppur NPP location area is noted.