Kinetics, SOA yields and chemical composition of secondary organic aerosol from β-caryophyllene ozonolysis with and without nitrogen oxides between 213 and 313 K

β-caryophyllene (BCP) is one of the most important sesquiterpenes (SQTs) in the atmosphere, with a large potential contribution to secondary organic aerosol (SOA) formation mainly from reactions with ozone (O3) and nitrate radicals (NO3). In this work, we study the temperature dependence of the kinetics of BCP ozonolysis, SOA yields, and SOA chemical composition in the dark and in the absence and presence of nitrogen oxides including nitrate radicals (NO3). We cover a temperature range of 213 K – 313 K, representative of tropospheric conditions. The oxidized components in both gas and particle phases were characterized on a molecular level by a Chemical Ionization Mass Spectrometer equipped with a Filter Inlet for Gases and AEROsols using iodide as the reagent ion (FIGAERO-iodide-CIMS). The batch mode experiments were conducted in the 84.5 m3 aluminium simulation chamber AIDA at the Karlsruhe Institute of Technology (KIT). In the absence of nitrogen oxides, the temperature-dependent rate coefficient of the endocyclic double bond in BCP reacting with ozone between 243 – 313 K are negatively correlated with temperature, corresponding to the following Arrhenius equation: k = (1.6 ± 0.4) × 10−15 × exp((559 ± 97)/T). The SOA yields increase from 16 ± 5 % to 37 ± 11% with temperatures decreasing from 313 K to 243 K at a total organic particle mass of 10 µg m−3. The variation of the ozonolysis temperature leads to substantial impact on the abundance of individual organic molecules. In the absence of nitrogen oxides, monomers C14-15H22-24O3-7 (37.4 %), dimers C28-30H44-48O5-9 (53.7 %) and trimers C41-44H62-66O9-11 (8.6 %) are abundant in the particle phase at 213 K. At 313 K, we observed more oxidized monomers (mainly C14-15H22-24O6-9, 67.5 %) and dimers (mainly C27-29H42-44O9-11, 27.6 %), including highly oxidized molecules (HOMs, C14H22O7,9, C15H22O7,9 C15H24O7,9) which can be formed via hydrogen shift mechanisms, but no significant trimers. In presence of nitrogen oxides, the organonitrate fraction increased from 3 % at 213 K to 12 % and 49 % at 243 K and 313 K, respectively. Most of the organonitrates were monomers with C15 skeletons and only one nitrate group. Higher oxygenated organonitrates were observed at higher temperatures, with their signal-weighted O : C atomic ratio increasing from 0.41 to 0.51 from 213 K to 313 K. New dimeric and trimeric organic species without nitrogen atoms (C20, C35) were formed in presence of nitrogen oxides at 298–313 K indicating potential new reaction pathways. Overall, our results show that increasing temperatures lead to a relatively small decrease of the rate coefficient of the endocyclic double bond in BCP reacting with ozone, but to a strong decrease in SOA yields. In contrast, the formation of HOMs and organonitrates increases significantly with temperature.

Flow Characteristics of the Nozzle Blade Cascade in the Mode of the Joint Operation with the Radial Diffuser

The obtained research data are given for the nozzle cascade used by a small-size gas turbine of an average fanning in combination with the radial diffuser. Aerodynamic characteristics of the nozzle blade cascade were determined in a wide range of a change in the Reynolds number varying from 4∙105 to 106 and the reduced velocity varying in the range of 0.4 to 1.13. The flow rate coefficient of the nozzle cascade was derived for all modes using the integral methods and the drainages behind the cascade. The kinetic energy loss coefficient and the flow angles were calculated using the measurement data of flow parameters in three control modes that were obtained due to the use of orientable pneumometric probes. When the expansion degree of the convergent –divergent annular duct behind the cascade is equal to 1.43 the flow in the narrow section of this duct is “enlocked” in the mode when the reduced velocity behind the cascade is equal to 1.127. At such velocity the Reynolds number 106 is self-similar for the flow rate coefficient. At lower values of Reynolds number, the decrease of it is accompanied by an intensive decrease in the flow rate coefficient for all the values of the reduced velocity. For the Reynolds number lower than 7∙105 an increase in the velocity results in a decreased flow rate coefficient. When this number exceeds 8∙105 an increase in the velocity results in an increase of the flow coefficient up to the moment when the flow is “enlocked” in the nozzle cascade.

Biomass burning plume chemistry: OH-radical-initiated oxidation of 3-penten-2-one and its main oxidation product 2-hydroxypropanal

In order to enlarge our understanding of biomass burning plume chemistry, the OH-radical-initiated oxidation of 3-penten-2-one (3P2), identified in biomass burning emissions, and 2-hydroxypropanal (2HPr) was investigated at 298 ± 3 K and 990 ± 15 mbar in two atmospheric simulation chambers using long-path FTIR spectroscopy. The rate coefficient of 3P2 + OH was determined to be (6.2 ± 1.0) × 10−11 cm3 molec.−1 s−1 and the molar first-generation yields for acetaldehyde, methyl glyoxal, 2HPr, and the sum of peroxyacetyl nitrate (PAN) and CO2, used to determine the CH3C(O) radical yield, were 0.39 ± 0.07, 0.32 ± 0.08, 0.68 ± 0.27, and 0.56 ± 0.14, respectively, under conditions where the 3P2-derived peroxy radicals react solely with NO. The 2HPr + OH reaction was investigated using 3P2 + OH as a source of the α-hydroxyaldehyde adjusting the experimental conditions to shift the reaction system towards secondary oxidation processes. The rate coefficient was estimated to be (2.2 ± 0.6) × 10−11 cm3 molec.−1 s−1. Employing a simple chemical mechanism to analyse the temporal behaviour of the experiments, the further oxidation of 2HPr was shown to form methyl glyoxal, acetaldehyde, and CO2 with estimated yields of 0.27 ± 0.08, 0.73 ± 0.08, and 0.73 ± 0.08, respectively.

Systematic kinetic study of magnesium production using magnesium oxide and carbonic materials at different temperatures

The main goal of this study was to determine the industrially best reductant for reduction of magnesium oxide to magnesium with wood charcoal and petroleum coke (petcoke) each in molar ratio 1:1 and 1:2 (oxidant:reductant) at high temperatures. In this study, a new and reliable combination of mathematical modeling and discrete numerical optimization theory by presenting 18 “mathematical filters” not relying only on statistical quantities of fitting (contrary to many similar researches) was introduced. The purpose of these filters was the determination of correct kinetic equation and therefore, the corresponding rate coefficient from among 18 equations most used at present in the challenging field of solid state chemical kinetics. With assistance of a new and fundamental mathematical function and the obtained values of rate coefficients, the function of rate coefficient in temperature was attained. The activation energy was then calculated as a function of temperature using the general definition of activation energy and the determined function for rate coefficient. The comparison between different reducing agents in the different conditions and with relevant previous study was accomplished to determine the best reducing agent from industry standpoint. Also, the areas under experimental data were calculated numerically and utilized for method validation and comparison. It turned out finally that relying only on fitting quantities in the solid state chemical kinetics can readily lead to wrong conclusions about the correct kinetic equation and about the most suitable reducing agent. It is obvious that the erroneous calculations and wrong decisions in the laboratory scale become significant and paramount in industry and this reveals the significance of rigorous mathematical analysis. Graphical abstract

Study on the impact of confining pressure on gas permeability of tight sandstone cores

Taking the tight sandstone core of Shengli Oilfield as the experimental sample, this paper studies the permeability variation of the tight sandstone under different confining pressures. The experimental results show that when the pore pressure is constant, the measured gas permeability of core decreases with the increase of confining pressure. Power function is more reasonable to describe the influence of confining pressure on permeability of tight sandstone between power function and exponential function. Analyze the impact of confining pressure on gas permeability of tight sandstone cores by using permeability change rate coefficient D and coefficient S.

The use of illite in function of filler applied in rubber blend

The presented work was dealing with the study of the commercial filler influence change in rubber blend by an alternative filler based on the clay mineral - illite. The focus of the presented work was aimed at the study of selected curing characteristics of rubber blend with addition of clay mineral filler and physico-mechanical properties of prepared vulcanizates. Curing characteristics, the processing safety, minimum and maximum torque, optimal curing time and curing rate coefficient were determined during the curing experiment phase. Selected physico-mechanical properties were given by the determination of hardness, tensibility and tensile strength. The obtained results proved the possibility of partial commercial filler replacement by an alternative filler and the positive effect of clay mineral on resulting important properties in rubber industry.

Biologycal aspect of Indian Scad (Decapterus russelli) (Ruppell,1830) caugth in Bali and Madura Straits, and Southern waters of East Java, Indonesia

The way to determine whether the Indian scad (D. russelli) comes from the same stock or not, is using estimation morphology and biology. The kinship of D. russelli in the three waters is not too close, and it has a very distant kinship with D. macarellus and D. kurroides. D. russelli and D. macrosoma in Bali Strait and South Java is close. The results of the analysis show that two of five components of the characteristic morphometric factor of D. russelli in the three waters have a character differential percentage of 37.73% and similarity of 62.27%. The growth rate obtained (L∞) from Bali Strait is 26,16 cm FL, the growth rate coefficient (K) is 0,63 per year, and (t0) is -0,20 years length maturity (Lm) male 13,9 cm FL and female 16,1 FL. The type of foods that is found are 12 phylums. The growth rate obtained (L∞) from Southern Waters of East Java of 28,28 cm FL, the growth rate coefficient (K) is 0,83 per year, and (t0) is -0,18 year, length maturity (Lm) male 15,3 cm FL female 16,7 cm FL. Type of foods that is found are 6 phylums. The growth rate obtained in Madura strait has an asymptotic length (Loo) 24,63 cm FL ; K 0,63 per year and t0 -0,27 year. Indian scad is a carnivore with the main food is Zooplankton (61%). using the morphological and biological approach, it is found that the D. russelli caught in the three waters come from a different stock.

Understanding the outbreak of COVID-19 in Ecuador

In this study is presented a mathematical approach that can be used to estimate the variability of the growth rate coefficient (λ), the total number of cases, and the midpoint of maximum infection due to the COVID-19 pandemic. The different parameters are quantified using one-year data set reported for Ecuador (from March 2020 to February 2021) and the (discrete or differential) logistic model. In particular, the results evidence that the most critical months of the pandemic in Ecuador were March and April 2020. In the following months, the outbreak continues with low growth rate values but in a variable way, which can be attributed to state health policies and the social behavior of the population. The estimated number of confirmed cases is around 409 K agrees with the data reported at the end of May 2021, validating the proposed mathematical approach.