Scaling laws for single-file diffusion of adhesive particles

Single-file diffusion refers to the Brownian motion in narrow channels where particles cannot pass each other. In such processes, the diffusion of a tagged particle is typically normal at short times and becomes subdiffusive at long times. For hard-sphere interparticle interaction, the time-dependent mean squared displacement of a tracer is well understood. Here we develop a scaling theory for adhesive particles. It provides a full description of the time-dependent diffusive behavior with a scaling function that depends on an effective strength of adhesive interaction. Particle clustering induced by the adhesive interaction slows down the diffusion at short times, while it enhances subdiffusion at long times. The enhancement effect can be quantified in measurements irrespective of how tagged particles are injected into the system. Combined effects of pore structure and particle adhesiveness should speed up translocation of molecules through narrow pores.Comment: 6 pages, 2 figures plus 4 pages, 3 figures in S

On TAML Catalyst Resting State Lifetimes:Kinetic, Mechanistic, and Theoretical Insight into Phosphate-Induced Demetalation of an Iron(III) Bis(sulfonamido)bis(amido)-TAML Catalyst

At ambient temperatures, neutral pH and ultralow concentrations (low nM), the bis(sulfonamido)bis(amido) oxidation catalyst [Fe{4-NO2C6H3-1,2-(NCOCMe2NSO2)2CHMe}(OH2)]− (1) has been shown to catalyze the addition of an oxygen atom to microcystin-LR. This persistent bacterial toxin can contaminate surface waters and render drinking water sources unusable when nutrient concentrations favor cyanobacterial blooms. In mechanistic studies of this oxidation, while the pH was controlled with phosphate buffers, it became apparent that iron ejection from 1 becomes increasingly problematic with increasing [phosphate] (0.3-1.0 M); 1 is not noticeably impacted at low concentrations (0.01 M). At pH &lt; 6.5 and [phosphate] ≥ 1.0 M, 1 decays quickly, losing iron from the macrocycle. Iron ejection is surprisingly mechanistically complex; the pseudo-first-order rate constant kobs has an unusual dependence on the total phosphate concentration ([Pt]), kobs = k1[Pt] + k2[Pt]2, indicating two parallel pathways that are first and second order in [phosphate], respectively. The pH profiles in the 5.5-8.3 range for k1 and k2 are different: bell-shaped with a maximum of around pH 7 for k1 and sigmoidal for k2 with higher values at lower pH. Mechanistic proposals for the k1 and k2 pathways are detailed based on both the kinetic data and density functional theory analysis. The major difference between k1 and k2 is the involvement of different phosphate species, i.e., HPO42- (k1) and H2PO4- (k2); HPO42- is less acidic but more nucleophilic, which favors intramolecular rate-limiting Fe-N bond cleavage. Instead, H2PO4- acts intermolecularly, where the kinetics suggest that [H4P2O8]2- drives degradation.</p

Monitoring of Gamma Radiation Prior to Earthquakes at a Study of Lithosphere-Atmosphere-Ionosphere Coupling in Northern Tien Shan

Monitoring of radiation background in the near-surface atmosphere and of gamma rays, geoacoustic emission, and temperature in a borehole at 40m depth, as well as Doppler sounding on a low-inclined radio pass proceed at the Tien Shan mountain station (3340m a.s.l.) in Northern Tien Shan with common goal to search for seismogenic effects preceding earthquake. The flux of gamma rays in the borehole varies negligibly between the days, and it is not influenced by precipitations. Characteristic bay-like drops of the gamma ray flux were found (2-8)days before the M5.0-M6.2 earthquakes. In a M4.2 earthquake event with the 5.3km epicenter distance anomalies were detected (7-10)days before the earthquake in variation of the gamma ray flux, geoacoustic emission, and temperature. Simultaneously with gamma rays, a disturbance was detected in the Doppler shift of the ionospheric signal. Similarly, ionosphere disturbances triggered by the growth of radioactivity in the near-surface atmosphere were found at retrospective analysis of the Doppler shift data acquired after underground nuclear explosions at the Semipalatinsk testing site. This effect is considered from the viewpoint of the lithosphere-atmosphere-ionosphere coupling concept

APPLICATION OF THE ACOUSTIC METHOD TO CONTROL THE HYDROGEN CONTENT OF TITANIUM STRUCTURES

В работе рассмотрено влияние водородного охрупчивания на структуру и физические свойства образцов из псевдо-α титанового сплава ПТ-3В. Анализ структурного состояния сплава показал, что с увеличением концентрации водорода наблюдается образование гидридных фаз TiHx. Также приведены результаты применения объемных и поверхностных упругих волн для контроля степени наводороживания конструкций из титанового сплава ПТ-3В. Наводороживание образцов осуществляли из газовой среды при температуре 550˚C, давлении 0,1 ат в течение 1,5; 3 и 5 часов. Содержание водорода в образцах определяли методом высокотемпературной экстракции на приборе ELTRA ОН 900.The paper considers the effect of hydrogen embrittlement on the structure and physical properties of samples from the pseudo-α titanium alloy PT-3V. Analysis of the structural state of the alloy showed that with an increase in the concentration of hydrogen, the formation of TiHx hydride phases is observed. The results of the application of volumetric and surface elastic waves to control the degree of flooding of structures made of titanium alloy PT-3V are also presented. The samples were hydrogenated from a gaseous medium at a temperature of 550°C, a pressure of 0.1 at for 1.5, 3 and 5 hours. The hydrogen content in the samples was determined by high-temperature extraction on the ELTRA OH 900 device.Исследование выполнено по гранту РНФ № 19-19-00332-П «Разработка научно-обоснованных подходов и аппаратно-программных средств мониторинга поврежденности конструкционных материалов на основе подходов искусственного интеллекта для обеспечения безопасной эксплуатации технических объектов в Арктических условиях»

INVESTIGATION OF THE FEATURES OF THE FORMATION OF THE STRUCTURE AND PROPERTIES OF 12H18N10T STEEL OBTAINED BY THE SLM METHOD

В работе рассмотрено влияние направления наплавки на структуру и физические свойства образцов из аустенитной нержавеющей стали 12Х18Н10Т. Анализ пикнометрического и металлографического результатов исследований показал, что при отдалении от подложки плотность снижается. Также была выявлена зависимость акустического параметра Dc от увеличения пористости в исследуемом образце.The paper considers the influence of the direction of surfacing on the structure and physical properties of samples made of austenitic stainless steel 12H18N10T. Analysis of the pycnometric and metallographic results of the studies showed that the density decreases with distance from the substrate. The dependence of the acoustic parameter Dc on the increase in porosity in the sample under study was also revealed

INFLUENCE OF THE PARAMETERS OF HOT ISOSTATIC PRESSING ON THE STRUCTURE AND PHYSICO-MECHANICAL PROPERTIES OF THE EP741 ALLOY

В данной работе рассмотрено влияние параметров (температура, давление) горячего изостатического прессования (ГИП) на структуру и физико-механические свойства сплава ЭП741. Получены микроструктуры сплава ЭП741 при разаличных температурах ГИП. Получены значения плотности и твёрдости и построены графики зависимостей физико-механических свойств от температуры ГИП. Определена оптимальная температура ГИП для жаропрочного никелевого сплава ЭП741.In this paper, the influence of the parameters (temperature, pressure) of hot isostatic pressing (HIP) on the structure and physico-mechanical properties of the EP741 alloy is considered. The microstructures of the EP741 alloy were obtained at different temperatures of the gypsum. The values of density and hardness are obtained and graphs of the dependences of physical and mechanical properties on the temperature of the HIP are constructed. The optimal temperature of the HIP for the heat-resistant nickel alloy EP741 has been determined