Additive singular spectral model of a dendrochronological signal

Relevance. Allocation of structural components in a dendrochronological signal of annual rings of coniferous trees expands the possibilities of the bioindication method and allows obtaining information about changes in environmental conditions in the past for extended territories. Aim. Creation of an additive singular spectral model based on the frequency trigonometric components of the dendrochronological signal; reconstruction of changes in the total ozone content in the atmosphere in the past, affecting the level of ultraviolet radiation in the B range radiation. Objects. Time series of total ozone content in the atmosphere (data from 1932), width and density of annual rings (data from 1686–2004) on the example of the territory near the observatory in Arosa, Switzerland, time series of stable oxygen isotopes δ18Oc, France. Methods. Time series analysis (decomposition of a time series, identification of model parameters, prediction of a time series), statistical analysis (F-criterion, χ2 – Pearson criterion), experimental measurements of the percentage components of the wood of annual rings, correlation analysis, spectral singular analysis. Results. Decomposition of the dendrochronological signal of individual chronologies into trigonometric components in the Caterpillar program. Correlation analysis of the sensitivity of trees to atmospheric effects. Reconstruction of the ozone level in the stratosphere using the first trigonometric component of the dendrochronological signal. In cellulose, the first low-frequency component of the signal and the structural component of wood, a reliable response of trees to long-period fluctuations in the total ozone content is recorded. This allows assessment of the impact of the stress factor on conditions of exploitation of forest resources. The use of data on the width of the annual rings allows you to expand the territorial boundaries of the method

Diastereoselective Heterocyclization of Geminal Bromo-fluoro Arylcyclopropanes by Nitrosonium Tetrafluoroborate: Access to 4-fluorinated Isoxazolines and Isoxazoles

A series of 5-aryl-4-bromo-4-fluoroisoxazolines was synthesized via nitrosation of 2-aryl-1-bromo-1-fluorocyclopropanes with NOBF4. It was shown that the E-isomers of the cyclopropanes react highly regio- and diastereoselectively leading exclusively to the E-isomers of the isoxazolines. The obtained 5-aryl-4-bromo-4-fluoroisoxazolines were transformed selectively into the corresponding 5-aryl-4-fluoro- or 5-aryl-4-bromoisoxazoles in good yields in the reaction with Lewis acids

Coprecipitation Synthesis of Nickel and Cobalt Hydroxides by Use Strong Based Anion Resin A300 in ОH - Form and NaOH Solution

Исследованы продукты анионообменного осаждения никеля и кобальта (II) из растворов их солей при их совместном присутствии в широком интервале молярных отношений металлов с использованием сильноосновного анионита фирмы Purolite А300 в ОН-форме в сравнении с щелочным осаждением этих солей. Показано, что продукты, полученные анионообменным осаждением, в отличие от осажденных NaOH, не содержат примесных ионов, их структура соответствует альфа-модификации гидроксида никеля, а размер частиц - 0,1-0,2 мкмCoprecipitation synthesis of nickel and cobalt hydroxides by use strong based anion resin A300 in ОH - form and NaOH solution has been investigated. The composition, structure and morphology of the samples were investigated by TGA, X-Ray diffraction, electron microscopy and IR-spectroscopy techniques

Coprecipitation Synthesis of Nickel and Cobalt Hydroxides by Use Strong Based Anion Resin A300 in ОH - Form and NaOH Solution

Исследованы продукты анионообменного осаждения никеля и кобальта (II) из растворов их солей при их совместном присутствии в широком интервале молярных отношений металлов с использованием сильноосновного анионита фирмы Purolite А300 в ОН-форме в сравнении с щелочным осаждением этих солей. Показано, что продукты, полученные анионообменным осаждением, в отличие от осажденных NaOH, не содержат примесных ионов, их структура соответствует альфа-модификации гидроксида никеля, а размер частиц - 0,1-0,2 мкмCoprecipitation synthesis of nickel and cobalt hydroxides by use strong based anion resin A300 in ОH - form and NaOH solution has been investigated. The composition, structure and morphology of the samples were investigated by TGA, X-Ray diffraction, electron microscopy and IR-spectroscopy techniques