A model for the distribution of aftershock waiting times

In this work the distribution of inter-occurrence times between earthquakes in aftershock sequences is analyzed and a model based on a non-homogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of inter-occurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.Comment: 4 pages, 3 figure

Chronicles of nature calendar, a long-term and large-scale multitaxon database on phenology

We present an extensive, large-scale, long-term and multitaxon database on phenological and climatic variation, involving 506,186 observation dates acquired in 471 localities in Russian Federation, Ukraine, Uzbekistan, Belarus and Kyrgyzstan. The data cover the period 1890-2018, with 96% of the data being from 1960 onwards. The database is rich in plants, birds and climatic events, but also includes insects, amphibians, reptiles and fungi. The database includes multiple events per species, such as the onset days of leaf unfolding and leaf fall for plants, and the days for first spring and last autumn occurrences for birds. The data were acquired using standardized methods by permanent staff of national parks and nature reserves (87% of the data) and members of a phenological observation network (13% of the data). The database is valuable for exploring how species respond in their phenology to climate change. Large-scale analyses of spatial variation in phenological response can help to better predict the consequences of species and community responses to climate change.Peer reviewe

Phenological shifts of abiotic events, producers and consumers across a continent

Ongoing climate change can shift organism phenology in ways that vary depending on species, habitats and climate factors studied. To probe for large-scale patterns in associated phenological change, we use 70,709 observations from six decades of systematic monitoring across the former Union of Soviet Socialist Republics. Among 110 phenological events related to plants, birds, insects, amphibians and fungi, we find a mosaic of change, defying simple predictions of earlier springs, later autumns and stronger changes at higher latitudes and elevations. Site mean temperature emerged as a strong predictor of local phenology, but the magnitude and direction of change varied with trophic level and the relative timing of an event. Beyond temperature-associated variation, we uncover high variation among both sites and years, with some sites being characterized by disproportionately long seasons and others by short ones. Our findings emphasize concerns regarding ecosystem integrity and highlight the difficulty of predicting climate change outcomes. The authors use systematic monitoring across the former USSR to investigate phenological changes across taxa. The long-term mean temperature of a site emerged as a strong predictor of phenological change, with further imprints of trophic level, event timing, site, year and biotic interactions.Peer reviewe

Heavy Oil Upgrading in the Presence of Water

В обзоре систематизированы результаты исследований в области облагораживания нетрадиционного (тяжелого) нефтяного сырья (ТНС) в присутствии воды в зависимости от ее фазового состояния, в температурном интервале ~150–550 ºС. В данном температурном диапазоне вода может существовать в субкритическом состоянии (Т = 100 – 374 ºС при давлении насыщенных паров воды), в форме сверхкритического флюида (Т ≥ 374 ºС, P ≥ 22,1 МПа), а также в форме перегретого водяного пара (при P < давления насыщения). Рассмотрены особенности процессов облагораживания ТНС, механизмы участия воды при взаимодействии с углеводородным сырьем и модельными соединениями, а также особенности применения катализаторов в процессеIn the review, the results of research in the field of heavy crudes upgrading in the presence of water are presented, depending on water phase states at temperatures ca. 150–550 ºС. In this temperature region, water can be in the subcritical state (compressed hot water at T = 100 – 374 ºС and saturated water vapor pressure), in the form of supercritical fluid (T ≥ 374 ºС, P ≥ 22.1 MPa) and in the form of superheated steam (at P < saturated water vapor pressure). Features of the heavy crudes upgrading including mechanisms of water involving in reactions with hydrocarbon feedstocks and model compounds as well as features of the use of catalysts are reviewe

Genesis Investigation of Niand Mo-Based Dispersed Catalysts of Steam Cracking of Heavy Oil

В данной статье приведены результаты исследования генезиса Ni- и Mo-содержащего дисперсного катализатора парового крекинга, полученного эмульсионным методом in-situ в тяжелой нефти методами МУРР и ПЭМ. Впервые исследованы структурные характеристики катализаторов и его предшественников на всех этапах получения и применения: в обратной эмульсии, дисперсии и в коксовом остатке, полученном в ходе каталитического парового крекинга. Показано, что Ni-содержащий предшественник преобразуется в более крупные агрегаты при переходе от дисперсии в тяжелой нефти до частиц Ni9S8 с размерами частиц 10–40 нм в коксовом остатке. В случае молибдена данной зависимости выявлено не было, после проведения процесса парового крекинга образуется два типа частиц: мелкие слоистые частицы сульфида молибдена с протяженностью 10–15 нм и более крупные частицы оксида молибдена с размерами 20–30 нмThis article presents the results of the genesis investigation of Ni- and Mo-based dispersed steam cracking catalyst produced via in-situ heavy oil emulsion decomposition. The structural characteristics of catalysts and their precursors have been studied by SAXS and TEM for the first time at all stages of production and operation: in reverse emulsions, dispersions and in the coke residues obtained after catalytic steam cracking process It is shown that the Ni-based precursor is converted to larger aggregates during transition from a dispersion in heavy oil to Ni9S8 10-40 nm particles in the coke residue. In the case of molybdenum this trend was not revealed, after steam cracking process two types of particles are formed: small layered MoS2 particles with a length of 10-15 nm and larger MoO2 20-30 nm particle

Noncovalent Interactions in Coordination Chemistry of Cyclic Trinuclear Copper(I) and Silver(I) Pyrazolates

Group 11 metals form with pyrazolate ligand complexes with a general formula of [MPz]n. The value of “n” varies depending on the type of substituent in the ligand and the metal atom. Copper(I) and silver(I) ions mainly form cyclic di-, tri-, and tetra-nuclear complexes or polymeric structures. Cyclic trinuclear d10 metal pyrazolates [MPzm]3 (M = Cu(I) and Ag(I); Pz = substituted pyrazolate ligand) are of particular interest because their planar structure allows them to form supramolecular aggregates via noncovalent metal–metal, metal–π, and metal–electron donor interactions. Designing complexes based on these interactions has been a focus of research for the last two decades. The ability of cyclic trinuclear copper(I) and silver(I) pyrazolates to form coordination and supramolecular structures determines their properties and potential applications in catalysis, gas sensing, molecular recognition, and photoluminescence. In this review, we discuss noncovalent interactions between cyclic trinuclear silver(I) and copper(I) complexes with various types of ligands