Hemostasis is a complex physiological mechanism that functions to maintain vascular integrity under any conditions. Its primary components are blood platelets and a coagulation network that interact ...to form the hemostatic plug, a combination of cell aggregate and gelatinous fibrin clot that stops bleeding upon vascular injury. Disorders of hemostasis result in bleeding or thrombosis, and are the major immediate cause of mortality and morbidity in the world. Regulation of hemostasis and thrombosis is immensely complex, as it depends on blood cell adhesion and mechanics, hydrodynamics and mass transport of various species, huge signal transduction networks in platelets, as well as spatiotemporal regulation of the blood coagulation network. Mathematical and computational modeling has been increasingly used to gain insight into this complexity over the last 30 years, but the limitations of the existing models remain profound. Here we review state-of-the-art-methods for computational modeling of thrombosis with the specific focus on the analysis of unresolved challenges. They include: a) fundamental issues related to physics of platelet aggregates and fibrin gels; b) computational challenges and limitations for solution of the models that combine cell adhesion, hydrodynamics and chemistry; c) biological mysteries and unknown parameters of processes; d) biophysical complexities of the spatiotemporal networks' regulation. Both relatively classical approaches and innovative computational techniques for their solution are considered; the subjects discussed with relation to thrombosis modeling include coarse-graining, continuum versus particle-based modeling, multiscale models, hybrid models, parameter estimation and others. Fundamental understanding gained from theoretical models are highlighted and a description of future prospects in the field and the nearest possible aims are given.
•The state of the art in modeling thrombus formation is presented.•Models at all scales of thrombus formation, such as the coagulation cascade, blood flow and blood cells, are considered.•The obstacles, limitations and challenges involved in building the above models and integrating into a whole are discussed.•The importance of theoretical modelling for thrombosis therapy in a heterogeneous population is highlighted.
We show that an electro-osmotic flow near the slippery hydrophobic surface depends strongly on the mobility of surface charges, which are balanced by counterions of the electrostatic diffuse layer. ...For a hydrophobic surface with immobile charges, the fluid transport is considerably amplified by the existence of a hydrodynamic slippage. In contrast, near the hydrophobic surface with mobile adsorbed charges, it is also controlled by an additional electric force, which increases the shear stress at the slipping interface. To account for this, we formulate electrohydrodynamic boundary conditions at the slipping interface, which should be applied to quantify electro-osmotic flows instead of hydrodynamic boundary conditions. Our theoretical predictions are fully supported by dissipative particle dynamics simulations with explicit charges. These results lead to a new interpretation of zeta potential of hydrophobic surfaces.
Abstract
The paper deals with petroleum road bitumen interacting with the components of a complex modifier. They are high-pressure polyethylene, thermoelastoplast, polymer packaging waste and ...surfactants. The analysis of changes are presented in the physical and mechanical properties of binders for road pavements obtained by Fourier-IR spectroscopy, optical methods and standard equipment for measuring the qualitative indicators of road binders based on petroleum bitumen.
The results of analytical and numerical studies of the internal structure of random packed beds of metal micro-particles are presented. To construct packed beds from mono- and polydisperse solid ...spheres, an algorithm for their random generation based on the discrete element method is used. Analysis of the structure of the packed bed includes the determination of porosity, specific surface area and tortuosity of the pores when changing powder particle sizes. A theoretical conclusion of these structural parameters is proposed in the form of formulas. The data obtained characterize the percolation properties of the granular medium, which affects the propagation and absorption of laser radiation in the volumetric layer of particles. Analysis is made of the influence of the physical properties of particles on the limiting characteristics of the penetration of laser radiation into a packed powder layer; the effects of radiation absorption and scattering in the pore space of a granular medium are estimated. A comparative analysis of approximate analytical and numerical solutions with the data of known experiments is carried out.
The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared ...spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm
−1
. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
The article considers general approaches and modern monitoring systems for rotary machines of electric generating equipment. The main characteristics of monitoring and diagnostics systems of Russian ...and foreign manufacturers are presented. Modern trends in the construction of intelligent systems for analyzing the performance of turbo generators and predicting possible failures in order to minimize the cost of repairs and forced shutdown of equipment are outlined. The concept of adaptive-predictive use of rotary machines, the difference from existing systems is the presence of adaptive module that allows to react to unwanted changes in real time and increase the predicted residual resource or eliminate the predicted probability of initially refusal.
► Operation of an associated petroleum gas catalytic reformer was reported. ► APG heavier hydrocarbon components fully converted into methane. ► The engine attained the nominal characteristics when ...it fueled by reformed APG. ► Payback period is shortened for power generation units equipped with APG reformer.
Laboratory studies of the reaction of steam reforming of light hydrocarbons into methane–hydrogen mixture were performed. Ni- and Ru-containing systems were studied as the catalysts. The design, scale-out, and operation of an APG catalytic reformer integrated with evaporator-heat-exchanger, water condenser and flame burner were reported. Conversion of heavier hydrocarbon components into methane–hydrogen gas mixture exceeded 95–99% during testing the catalytic reformer at 270–360°C. Increasing reaction temperature led to increasing H2 and CO contents in the reaction mixture and complete conversion of LPG and ethane fractions. Both initial and reformed APG were used for fueling a power generation unit on the base of gas internal combustion engine MTES-30. In case of initial APG fueling, the power derating was 22%, exhaust gas contained black smoke. When the power generation unit was fueled by methane–hydrogen mixture produced by APG catalytic reforming, the engine power attained the nominal value; the engine showed excellent dynamic and temperature characteristics, stably supported crank rotation frequency.
According to economic analysis concerning different types of power plants with electric power of ∼1000kW, the plants equipped with a catalytic reformer of APG into methane–hydrogen mixture show faster payback of capital investments, as compared to the plants fed by APG directly, due to longer service life, longer overhaul intervals, and low rated power losses. Сatalytic reforming of APG into methane–hydrogen mixture is a promising approach for solving APG utilization problem.
A new nonlinear lattice model for an influence of the hydrogen concentration on the elastic constants of the lattice model of a material is developed. A weakly nonlinear long-wavelength continuum ...model is considered, and a model nonlinear equation for the dynamics of concentration of hydrogen is obtained asymptotically. The model predicts a decrease in the stiffness coefficient as well as a light local moving increase due to the localized nonlinear concentration wave propagation.
Design of oxide and nanocomposite materials with high mixed protonic-electronic conductivity such as lanthanide niobates and tungstates is encouraging approach in developing hydrogen separation ...membranes. This work aims at elucidating the relation of structure, oxygen and protonic mobility of such materials. La0.99Ca0.01NbO4, LaNb3O9 and Nd5.5WO11.25−δ were synthesized by Pechini and citrate route. Nanocomposites with LaNb3O9 and Ni + Cu were prepared by ultrasonic dispersion or mechanical treatment in a high energy mill and wet impregnation, then sintered using conventional thermal sintering and hot pressing. All obtained materials were characterized using XRD, SEM, TEM with EDX analysis, IR and Raman spectroscopy. The oxygen and proton mobility were studied by isotope exchange, unit cell volume and weight relaxation techniques. The proton conductivity was studied by Van der Pauw technique. The main phases were scheelite for La0.99Ca0.01NbO4, perovskite for LaNb3O9 and fluorite for Nd5.5WO11.25−δ, extended defects were observed agreeing with IR and Raman spectroscopy data. The oxygen mobility studies revealed two types of bulk oxygen related to two phases in samples. D2O exchange studies demonstrated very fast protonic transport in samples. H2O desorption experiments revealed the working temperature range being 300–450 °C. The protonic conductivity values (~10−4 Ω−1 cm−1 at 400 °C) agree with the literature data and are sufficiently high for the practical application. Proton tracer and chemical diffusion coefficients values are ~10−11 and ~10−3 cm2/s at working temperatures, respectively. Successful test of proton conducting membrane with Nd5.5WO11.25−δ based functional layer showing promising performance has been carried out.
•An approach of obtaining Ln niobates and tungstates was developed.•High protonic mobility was demonstrated.•Testing supported membrane based on Nd5.5WO11.25−δ in H2 separation demonstrated promising performance.
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