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Calculations are performed for the fields, amplitude, and dispersion characteristics of a surface acoustic wave in the “viscous fluid half-space–solid half-space” and “viscous fluid layer–elastic ...half-space” systems taken into account the shear components in the fluid. The resulting radiation pressure is calculated, which occurs in a viscous fluid layer under the impact of a standing surface wave and acts on the elementary fluid volume due to the nonlinearity of the equations of motion in single- and two-mode regimes. It is shown that viscosity results in a violation in the perfect periodicity and symmetry of the fields of the radiation forces and acoustic streaming. The shear components result in considerable radiation pressure forces localized in a narrow domain in the vicinity of the interface. The excitation of several wave modes in a system makes it possible to generate complex spatial distributions of radiation force fields. Then controlling the wave frequency and the layer thickness, one can reach either the predominance of the single-mode field or a comparable contribution of several modes. The fundamental mode is predominant in the vicinity of a wave resonance.
Immune thrombocytopenia (ITP) is an autoimmune condition primarily induced by the loss of immune tolerance to the platelet glycoproteins. Here we develop a novel flow cytometry approach to analyze ...integrin αIIbβ3 functioning in ITP in comparison with Glanzmann thrombasthenia (GT) (negative control) and healthy pediatric donors (positive control). Continuous flow cytometry of Fura-Red-loaded platelets from whole hirudinated blood was used for the characterization of platelet responses to conventional activators. Calcium levels and fibrinogen binding were normalized to ionomycin-induced responses. Ex vivo thrombus formation on collagen was observed in parallel-plate flow chambers. Platelets from all ITP patients had significantly higher cytosolic calcium concentration in the quiescent state compared to healthy donors (15 ± 5 nM vs. 8 ± 5 nM), but calcium increases in response to all activators were normal. Clustering analysis revealed two subpopulations of ITP patients: the subgroup with high fibrinogen binding (HFB), and the subgroup with low fibrinogen binding (LFB) (8% ± 5% for LFB vs. 16% ± 3% for healthy donors in response to ADP). GT platelets had calcium mobilization (81 ± 23 nM), fibrinogen binding (5.1% ± 0.3%) and thrombus growth comparable to the LFB subgroup. Computational modeling suggested phospholipase C-dependent platelet pre-activation for the HFB subgroup and lower levels of functional integrin molecules for the LFB group.
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In the post-Soviet space, Ukraine has seen intensive development of private solar generation, which is facilitated by the “green” tariff legally introduced in the country on June 2015, which allows ...small private power plants with a capacity of up to 30 kW not only to consume energy for their needs, but also to sell surplus to the centralized network. In the country there is a well-defined algorithm for the relationship between the object of solar generation and the energy supplying organization. The three solar power plants of small capacity that are located in private households in the city of Melitopol’ is the striking example of this interaction. The analysis of the structure of these power plants, the orientation of the photovoltaic panels and their operation allows us to say that the electrotechnical generating equipment of these plants is effectively operated yearround. In the warm season, the consumed electric energy is enough to supply household and communal needs, and sell the surplus into the grid at the “green” tariff. In the cold season, at not all of these private power plants are the surplusses of the energy supplying organizations sold, since most of the electricity they generate is spent on heating the premises and supplying hot water. Today the possibility of increasing the power generation by photovoltaic modules within the framework of the quotas permitted by the “green” law is being considered.
The ability of platelets to carry out their hemostatic function can be impaired in a wide range of inherited and acquired conditions: trauma, surgery, inflammation, pre-term birth, sepsis, ...hematological malignancies, solid tumors, chemotherapy, autoimmune disorders, and many others. Evaluation of this impairment is vitally important for research and clinical purposes. This problem is particularly pronounced in pediatric patients, where these conditions occur frequently, while blood volume and the choice of blood collection methods could be limited. Here we describe a simple flow cytometry-based screening method of comprehensive whole blood platelet function testing that was validated for a range of pediatric and adult samples (n = 31) in the hematology hospital setting including but not limited to: classic inherited platelet function disorders (Glanzmann's thrombasthenia; Bernard-Soulier, Wiscott-Aldrich, and Hermasky-Pudlak syndromes, MYH9-dependent thrombocytopenia), healthy and pre-term newborns, acute and chronic immune thrombocytopenia, chronic lympholeukemia, effects of therapy on platelet function, etc. The method output includes levels of forward and side scatter, levels of major adhesion and aggregation glycoproteins Ib and IIb-IIIa, active integrins' level based on PAC-1 binding, major alpha-granule component P-selectin, dense granule function based on mepacrine uptake and release, and procoagulant activity quantified as a percentage of annexin V-positive platelets. This analysis is performed for both resting and dual-agonist-stimulated platelets. Preanalytical and analytical variables are provided and discussed. Parameter distribution within the healthy donor population for adults (n = 72) and children (n = 17) is analyzed.
Studies on platelet function in children older than neonatal period are few and their results are controversial. The pediatric platelets were alternatively reported to be more active or less active ...than adults' ones. We compared platelet function in the several age groups of children to adults and evaluated the age when platelet function reaches the adults' status. The study included 76 healthy children and 49 healthy adult volunteers. Types of platelet activation used included: collagen-related peptide (CRP) and PAR-1 activating peptide SFLLRN; SFLLRN, PAR-4 activating peptide AYPGKF and adenosine diphosphate (ADP); ADP. The parameters determined included forward (FSC) and side scatter (SSC), CD42b, CD61, CD62P, PAC-1, annexin V binding and mepacrine release levels. Resting pediatric platelets were similar to adults' platelets except for 1.2-fold decreased FSC and dense granules volume in youngest children, and 2.5-fold increased annexin V level in children aged 1-10 years. After CRP+SFLLRN stimulation, pediatric platelets had a 1.2-fold lower alpha- and 1.1-fold lower dense granule release than adults. For SFLLRN+AYPGKF+ADP stimulation, this was observed only for youngest children. The response to ADP stimulation was identical for pediatric platelets and adults. Pediatric platelets have lower granular release than adults' platelets, which persists until the age of 18.
High-power IGBTs are used in power electronic converters in a variety of applications: traction drives, renewable power converters, mining equipment, oil and water pumping, and so on. To control a ...transistor, a special gate driver board is required. This board converts the logical control signal into the appropriate voltage values necessary to turn the resistor on and off. Gate drivers can perform the protection functions of IGBTs using hardware and algorithmic approaches. Application-specific integrated circuits are often used in driver solutions to implement control and protection. The development of an application-specific integrated circuit is a time-consuming and expensive procedure, which increases the cost of the driver. This paper describes the control and protection algorithms implemented in an intelligent IGBT driver based on a low-cost microcontroller. The use of the microcontroller makes the gate driver design more flexible and allows for the accurate tuning of the protection thresholds. The gate driver protects the IGBT from short-circuiting, overcurrent, and overvoltage, monitors the voltage supply, and controls the switch on and switch off processes in the transistor. The performance of the protection algorithms was tested experimentally using a specialized test bench.
High mineralization of water complicates the use of foam in reservoir conditions. Anionic–nonionic surfactants are one of the best candidates for these conditions since they have both high surface ...activity and salt tolerance. One of the ways to obtain anionic–nonionic surfactants is to modify nonionic surfactants by an anionic group. The type of the group and its chemical structure can strongly affect the properties of the surfactant. In this work, widely-produced nonionic surfactant nonylphenol (12) ethoxylate (NP12EO) was modified by new types of carboxylic groups through the implementation of maleic (NP12EO-MA) and succinic (NP12EO-SA) anhydrides with different saturation levels. The main objectives of this work were to compare synthesized surfactants with nonionic precursor and to reveal the influence of unsaturated bonds in the carboxyl group on the properties of the foam. NaCl concentration up to 20 wt% was used to simulate high mineralization conditions, as well as to assess the effect of unsaturated bonds on foam properties. Synthesized anionic–nonionic surfactants retained surfactant solubility and long-term stability in high-salinity water, but have better foaming ability, as well as higher apparent viscosity, in porous media. The presence of an unsaturated bond in NP12EO-MA surfactant lowers foaming ability at high mineralization.
The selection of effective surfactants potentially can mobilize oil up to 50% of residuals in mature carbonate oilfields. Surfactants’ screening for such oilfields usually is complicated by the high ...salinity of water, high lipophilicity of the rock surface, and the heterogeneous structure. A consideration of features of the oilfield properties, as well as separate production zones, can increase the deep insight of surfactants’ influence and increase the effectiveness of surfactant flooding. This article is devoted to the screening of surfactants for two production zones (Bashkirian and Vereian) of the Ivinskoe carbonate oilfield with high water salinity and heterogeneity. The standard core study of both production zones revealed no significant differences in permeability and porosity. On the other hand, an X-ray study of core samples showed differences in their structure and the presence of microporosity in the Bashkirian stage. The effectiveness of four different types of surfactants and surfactant blends were evaluated for both production zones by two different oil displacement mechanisms: spontaneous imbibition and filtration experiments. Results showed the higher effect of surfactants on wettability alteration and imbibition mechanisms for the Bashkirian cores with microporosity and a higher oil displacement factor in the flooding experiments for the Vereian homogeneous cores with lower oil viscosity.
Surfactant flooding can mobilize trapped oil and change the wettability of the rock to be more hydrophilic, which increases the oil recovery factor. However, the selection of surfactants is difficult ...in the case of high salinity conditions. In this work, we synthesized three novel anionic-nonionic surfactants based on widely used nonionic surfactant nonylphenol polyethoxylated (NPEO) and evaluated their efficiencies for enhanced oil recovery (EOR) in high salinity water (20% NaCl). The modified surfactants showed a decrease in interfacial tension (IFT) up to 10 times compared with the nonionic precursor. All surfactants had changed the wettability of rock to be more hydrophilic according to contact angle measurements. The effectiveness of surfactants was proved by spontaneous imbibition experiments, in which the synthesized surfactants showed a better displacement efficiency and increased oil production by 1.5–2 times. Filtration experiments showed an increase in oil recovery factor by 2–2.5 times in comparison with the nonionic NPEO. These promising results prove that the synthesis of new surfactants by modifying NPEO is successful and indicate that these novel surfactants have a great potential for EOR in high salinity reservoirs.
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