Fraction Of Fluid Research Articles

Development of singular value decomposition based solution scheme for a numerical simulation of multiphase flow

This paper presents an innovative solution scheme that may resolve the numerical challenges of simulating the phase appearance and disappearance phenomena in multiphase flow. In this study, a least square problem for the mass and internal energy conservation equations is reviewed, and its inherent ill-posedness, originating from the rank deficiency of the coefficient matrix, in the inverse problem is introduced. Since building mathematically well-conditioned matrices is essential to avoiding the numerical instability as well as the singularity of matrices, first of all, a new solution scheme for the mass and internal energy conservation equations for the simulation of multiphase flow in which phase can appear and disappear under various flow conditions is derived based on a truncated Singular Value Decomposition (SVD)-based low rank approximation. The truncated SVD-based low rank approximation is then used to solve the mass and internal energy conservation equations by computing the pseudo inverse of the low rank approximation matrix. The field equations and closure relations currently being developed by introducing arbitrary values, which replace an extremely low volume fraction of fluids, are redefined in this study. As such, the physical phenomena themselves are directly considered without any modifications to the mathematical equations to compute phase transitions. The characteristics of phase transition are classified into convection, vaporization, and condensation over a wide range of fluid conditions, and the verification of the proposed solution method is completed through simulations of the 3 phase transition mechanisms. The SVD-based low rank approximation method improves computations of phase transition as simulation results indicate that the proposed solution scheme describes the physics better than the conventional one.

Spatiotemporal characterisation of ischaemic lesions in transient stroke animal models using diffusion free water elimination and mapping MRI with echo time dependence

Background and purposeThe excess fluid as a result of vasogenic oedema and the subsequent tissue cavitation obscure the microstructural characterisation of ischaemic tissue by conventional diffusion and relaxometry MRI. They lead to a pseudo-normalisation of the water diffusivity and transverse relaxation time maps in the subacute and chronic phases of stroke. Within the context of diffusion MRI, the free water elimination and mapping method (FWE) with echo time dependence has been proposed as a promising approach to measure the amount of free fluid in brain tissue robustly and to eliminate its biasing effect on other biomarkers. In this longitudinal study of transient middle cerebral artery occlusion (MCAo) in the rat brain, we investigated the use of FWE MRI with echo time dependence for the characterisation of the tissue microstructure and explored the potential of the free water fraction as a novel biomarker of ischaemic tissue condition. MethodsAdult rats received a transient MCAo. Diffusion- and transverse relaxation-weighted MRI experiments were performed longitudinally, pre-occlusion and on days 1, 3, 4, 5, 6, 7 and 10 after MCAo on four rats. Histology was performed for non-stroke and 1, 3 and 10 days after MCAo on three different rats at each time point. ResultsThe free water fraction was homogeneously increased in the ischaemic cortex one day after stroke. Between three and ten days after stroke, the core of the ischaemic tissue showed a progressive normalisation in the amount of free water, whereas the inner and outer border zones of the ischaemic cortex depicted a large, monotonous increase with time. The specific lesions in brain sections were verified by H&E and immunostaining. The tissue-specific diffusion and relaxometry MRI metrics in the ischaemic cortex were significantly different compared to their conventional counterpart. ConclusionsOur results demonstrate that the free water fraction in FWE MRI with echo time dependence is a valuable biomarker, sensitive to the progressive degeneration in ischaemic tissue. We showed that part of the heterogeneity previously observed in conventional parameter maps can be accounted for by a heterogeneous distribution of free water in the tissue. Our results suggest that the temporal evolution of the free fluid fraction map at the core and inner border zone can be associated with the pathological changes linked to the evolution of vasogenic oedema. Namely, the homogeneous increase in free water one day after stroke and its tendency to normalise in the core of the ischaemic cortex starting three days after stroke, followed by a progressive increase in free water at the inner border zone from three to ten days after stroke. Finally, the monotonous increase in free fluid in the outer border zone of the cortex reflects the formation of fluid-filled cysts.

Прогноз фазового состояния залежей углеводородов в ловушках комбинированного строения

The possibilities of predicting the phase state of hydrocarbon deposits by geochemical methods are considered. The article briefly describes the well-known gas-geochemical and petrochemical forecasting methods, and also proposes to use trace element indicators of fluids for these purposes. Based on the study of the distribution of the trace element composition of oils and condensates in Western Siberia, Turkmenistan, the Caspian Sea region, New Zealand and some other regions, the trace element geochemical indicators of naphthides are recommended for diagnostics of oil and gas condensate systems. The fact of the presence of trace elements in the light fractions of hydrocarbon fluids and the revealed genetic differences between oils and condensates make it possible to use trace element characterization of fluids for practical problems of oil and gas prospecting geology. Since by now hydrocarbon production reserves in anticlinal structures is nearing exhaustion, considerable attention is paid to complex combined traps confined to greater depths and severe thermobaric conditions.

A thermomechanical and photochemical description of the phase change process in roll-to-roll nanoimprinting lithography

In this paper, a model for the phase change process due to irradiation with an Ultraviolet (UV) light in a mold filled with a viscoelastic fluid in roll-to-roll nanoimprinting lithography is developed. Employing a thermomechanical approach, constitutive equations for the phase change of a mixture of viscoelastic fluid and solid constituents of the polymer are derived. A general model describing phase change that relates both thermomechanics and photochemistry is presented. A function defining the mass fractions of fluid and solid in the mixture is utilized in the thermomechanical description, and the governing equations for the evolution of the fluid and solid mixtures are obtained based on photochemical reactions under UV light. General properties and kinematic equations that impact phase change in terms of material properties and process parameters are obtained. A simplification of the model without sacrificing the underlying physics to make the problem amenable to analysis is put into place. The general model of phase transition is simplified by assuming that the gradient of the displacement, the strain and its time rate, are small; this results in an integro-differential quasilinear system of equations. A numerical scheme is proposed to solve the problem and results from the numerical simulations are presented and discussed.

Improving the Measurement of Volume Fraction of Multiphase Fluids Based on Attenuation of Gamma Rays Without the Use of Artificial Intelligence

Improving the Measurement of Volume Fraction of Multiphase Fluids Based on Attenuation of Gamma Rays Without the Use of Artificial Intelligence

Dispersed Gold and Associated Disseminated Mineralization of Leucogranites of the Dukat Ore Field as Indicators of the Generation Conditions of Magmatogene Gold-Bearing Fluids

Abstract —We present data on dispersed gold and associated disseminated mineralization of leucogranites controlling the location of the Dukat epithermal Au–Ag deposit. The data suggest the formation and burial of small portions of oversaturated gold-bearing fluids in hypabyssal magmatic bodies. The lower (relative to silver) contents of gold in the deposit ores and the high Ag/Au ratios (350–550) are due to the limited occurrence of oxidized gold-bearing fractions of magmatogene fluids. This limitation is explained by the active interaction of late magmatic portions of fluids and the material of the host carbonaceous volcanosedimentary unit and by the formation of an environment favorable for the concentration, migration, and deposition of manganese, silver, and nonferrous-metal compounds.

Evaluating numerical simulation errors of CO[formula omitted]-brine flow with capillary heterogeneity using a 1D semi-analytical solution

Modeling CO2-brine flow related to CO2 storage in saline aquifers involves intense numerical simulations. One of the important processes associated with these flows, allowing for safe long term storage of CO2, is residual trapping. For accurate modeling of trapping, capillary heterogeneity should be incorporated in the models. However, there have been some reports of increased numerical simulation errors associated with these models and yet no systematic study of their accuracy has been carried out.We compare results of two numerical simulators to a semi-analytical solution of 1D two-phase immiscible steady state flow with capillary heterogeneity. Simulation errors are calculated for a wide range of different flow rates, fluid fractions, capillary pressure curves and heterogeneities. Results show that capillary pressure and saturation errors increase with smaller dimensionless capillary number and reach large values of 25−50% for many cases. It is shown that the errors are related to capillary heterogeneity and therefore increase also with larger variance of log permeability. Finally, a new approach for predicting numerical errors without employing an analytical solution is proposed, i.e., the error indicator analysis.

Origins and pathways of deeply derived carbon and fluids observed in hot spring waters from non-active volcanic fields, western Kumamoto, Japan

Natural springs containing volcanic and magmatic components occur in association with these activities. However, features of deeply originated fluids and solutes were less documented from fields, where active volcanic and magmatic activities are not distributed. To characterize the presence of deep components and identify their major pathways 28 groundwater samples (~ 1230 m deep) were collected from hot spring sites located at western coast of Kumamoto, southwestern Japan, where the typical subduction related magmatisms are absent. The samples were measured for dissolved ion concentrations and stable isotope ratios (δ2HH2O, δ18OH2O, δ13CDIC and δ34SSO4) that were compared with data of 33 water samples from vicinity surface systems. The groundwaters were classified into three types based on major hydrochemistry: high Cl− fluid, low concentration fluid, and high HCO3− fluid. Our data set suggests that the high Cl− fluid was formed by saline water mixing with aquifer waters of meteoric origin and subsequently evolved by reverse cation exchange. The low concentration fluid is identical to regional aquifer water of meteoric origin that was subjected to cation exchange. The high HCO3− fluid showed the highest HCO3− concentrations (~ 3,888 mg/l) with the highest δ13CDIC (up to − 1.9‰). Based on our carbon mixing model and observed δ2HH2O and δ18OH2O shifts, it is suggested that dissolved carbon of mantle origin and small fraction of fluids generated in deep crust were transported towards surface through structural weakness under open tectonic setting. These deeply derived components were then mixed with waters in the surface systems and diluted. Their impacts on surface hydrological systems were limited in space except few locations, where deeply connected pathways are anticipated along active structural deformations.

Magma reservoir beneath Azumayama Volcano, NE Japan, as inferred from a three-dimensional electrical resistivity model explored by means of magnetotelluric method

An electrical resistivity model beneath Azumayama Volcano, NE Japan, is explored using magnetotelluric method to probe the magma/hydrothermal fluid distribution. Azumayama is one of the most concerning active volcanoes capable of producing a potential eruption triggered by the 2011 Tohoku-Oki Earthquake. The three-dimensional resistivity model reveals a conductive magma reservoir (< 3 Ωm) at depths of 3–15 km below sea level (bsl). The 67% and 90% confidence intervals of resistivity are 0.2–5 Ωm and 0.02–70 Ωm, respectively, for the magma reservoir. We assumed dacitic melt + rock at a shallow depth of 4 km bsl and andesitic melt + rock at a greater depth of 9 km bsl. The confidence interval of resistivity cannot be explained by using dacitic melt + rock condition at a depth of 4 km bsl. This suggests that very conductive hydrothermal fluids coexist with dacitic melt and rock in the shallow part of the magma reservoir. For the depth of 9 km bsl, the 67% confidence interval of resistivity is interpreted as water-saturated (8.0 weight %) andesitic melt–mafic rock complex with melt volume fractions greater than 4 volume %, while the shear wave velocity requires the fluid and/or melt volume fraction of 6–7 volume % at that depth. Considering the fluid and/or melt volume fraction of 6–7 volume %, the conductive hydrous phase is likewise required to explain the wide range of the 67% confidence interval of resistivity. The Mogi inflation source determined from geodetic data lies on the resistive side near the top boundary of the conductive magma reservoir at a depth of 2.7 or 3.7 km bsl. Assuming that the resistivity of the inflation source region is above the upper bound of the confidence interval of resistivity for the conductive magma reservoir and that the source region is composed of hydrothermal fluid + rock, the resistivity of the source region is explained by a hydrothermal fluid volume fraction below 5 volume %, which is the percolation threshold porosity in an effusive eruption. This indicates that the percolation threshold characterizes the inflation source region.

Propagation regimes, transition times, and approximate universality in 2D hydraulic fracture propagation with fluid lag

During its lifetime, a hydraulic fracture is known to traverse a trajectory in a region of a parametric space of non-dimensional evolutionary parameters. The topology of this diagram depends upon the phenomena considered. For the specific case of a 2D-plane strain fracture propagating in an elastic solid on a straight path normal to the minimum compressive stress, with a constant rate of injection of an incompressible newtonian fluid, and without leak-off, the diagram is a triangle whose vertices are typically called O, M, and K. The non-dimensional parameters are the toughness K and remote stress T (monotonically increasing with time). At each point in the trajectory P(t)=(K,T)(t), the configuration of the fracture is essentially described by several non-dimensional variables, in this case the opening Ω0 and pressure Π0 at the inlet, and the length γ. When fluid lag is considered, as in this case, a fourth variable (e.g., the fluid fraction ξf) can be appended to build the descriptive set F0={Ω0,Π0,γ,ξf}. Various propagation regimes are observed across the MKO triangle.As the main results, we: (1) provide specific, K-dependent transition times among the propagation regimes; and (2) found that the transient evolutions of all propagating cracks with moderate values of the non-dimensional toughness (K≳0.3), from the OK edge to the MK edge, are contained in a thin bundle about a universal curve in the F0-space. This result can be applied, e.g., to readily setup approximate initial conditions for more detailed hydraulic fracture propagation simulations. In addition, we developed a four-parameter family of parametrizations of the MKO triangle suitable for plotting trajectories and other loci on the triangle.

Intraperitoneal Activation of Coagulation and Fibrinolysis in Patients with Cirrhosis and Ascites.

Development of ascites is the most common form of decompensation of cirrhosis. We aimed to investigate the coagulation system in ascitic fluid and plasma of patients with cirrhosis. We determined coagulation parameters and performed clotting and fibrinolysis experiments in ascitic fluid and plasma of thoroughly characterized patients with cirrhosis and ascites ( n = 25) and in plasma of patients with cirrhosis but without ascites ( n = 25), matched for severity of portal hypertension. We also investigated plasma D-dimer levels in an independent cohort of patients ( n = 317) with clinically significant portal hypertension (HVPG ≥ 10 mmHg), grouped according to ascites severity. Ascitic fluid was procoagulant in a clotting assay. The procoagulant potential of ascitic fluid was abolished by depletion of extracellular vesicles from ascitic fluid by filtration or by addition of a tissue factor-neutralizing antibody. Compared with plasma, extracellular vesicle-associated tissue factor activity was high in ascitic fluid, while activities of other coagulation factors were low. The extracellular vesicle-depleted fraction of ascitic fluid induced fibrinolysis, which was prevented by aprotinin, indicating the presence of plasmin in ascitic fluid. Plasma peak thrombin generation and parameters reflecting fibrinolysis were independently associated with the presence of ascites. Finally, plasma D-dimer levels were independently linked to ascites severity in our second cohort comprising 317 patients. In conclusion, coagulation and fibrinolysis become activated in ascites of patients with cirrhosis. While tissue factor-exposing extracellular vesicles in ascitic fluid seem unable to pass the peritoneal membrane, fibrinolytic enzymes get activated in ascitic fluid and may re-enter the systemic circulation and induce systemic fibrinolysis.

Lithospheric electrical structure beneath the Cathaysia Block in South China and its tectonic implications

To better constrain the heat source of the geothermal system and lithospheric thinning mechanism of the Paleo-Pacific subduction zone, data from 35 broadband magnetotelluric (MT) stations were collected in 2020 along a 180-km-long NW-trending profile in the Cathaysia Block. Based on the measured data, we obtained the lithospheric electrical structure of the Cathaysia Block in South China using the 3D MT inversion code of ModEM. The final resistivity structure along the profile shows a series of highly conductive anomalies and highly resistive anomalies. The highly resistive anomalies in the upper crust correspond well with the distribution of magmatic rocks, which extend downwards to depths of 20 km. The highly resistive anomalies with a depth of 20–40 km are interpreted as crustal mafic sills derived from the mantle. The crustal conductors at depths of 5–15 km are typically interpreted as accumulations of aqueous fluids, which originate from the dehydration of the slab during the flat-slab subduction of the Paleo-Pacific Plate and are confined in the crust by impermeable layers. Fluid fractions of 0.8–9% would be required to explain the observed conductance values. The MT results indicate that there is no magma chamber or partial melt beneath the geothermal system. Therefore, the heat source of the geothermal system in the Cathaysia Block is radiogenic heat produced by the decay of radioactive elements in the crust. Thermal erosion has played a central role in lithospheric thinning and crust–mantle interaction of the Cathaysia Block.

Optimization based methodology to design metal hydride reactor for thermal storage application

A metal hydride based thermal energy storage system offers high energy density, provides longer storage time and requires less storage space compared to either conventional or phase change material based thermal energy storage systems. However, the design of such system is considered significantly complex. In this study, Taguchi method coupled with grey relational analysis was used to optimize the design parameters i.e. diameter of helical tube (dh), major diameter of helical tube (dm), number of turns of helical tube (N) and velocity of heat transfer fluid (Vf) for the helical tube heat exchanger embedded inside metal hydride reactor for thermal energy storage application. These parameters were optimized subjected to achieve maximum reaction fraction (C0) and maximum outlet temperature of heat transfer fluid (To). The performance of all experiments in the orthogonal array which were used for Taguchi and Grey relational analysis were evaluated by 3-D numerical simulations performed in commercial software COMSOL 5.3a. This methodology used is significantly computationally efficient as the number of required simulations reduced by 90% as compared to the conventional parametric study-based methodology. The required number of simulations reduced from 81 to 9 with the use of proposed methodology. Further, the added advantage of this methodology is, it enables to estimate an optimized level of the parameters by considering all the objective functions (C0, To) simultaneously. Lastly, the performance of the optimally designed systems was compared with all the orthogonal array experiments and it was found out that the optimized system designs were found to have better performance considering the objective parameters i.e., C0 and To as compared with the other experiments of the orthogonal array.

The composition of subduction zone fluids and the origin of the trace element enrichment in arc magmas

The partitioning of major and trace elements between eclogite and aqueous fluids with variable salinity was studied at 700–800 °C and 4–6 GPa in piston cylinder and multi anvil experiments. Fluid compositions were determined using the diamond trap technique combined with laser ablation ICP-MS measurements in the frozen state. In addition to NaCl, SiO2 is the main solute in the fluids. The fluid/eclogite partition coefficients of the large ion lithophile elements (LILE), such as Rb, Cs, Sr, and Ba as well as those of the light rare earths (LREE), of Pb, and of U increase by up to three orders of magnitude with salinity. These elements will therefore be efficiently transported by saline fluids. On the other hand, typical high field strength elements, such as Ti, Nb, and Ta, are not mobilized even at high salinities. Increasing temperature and pressure gradually increases the partitioning into the fluid. In particular, Th is mobilized by silica-rich fluids at 6 GPa already at low salinities. We show that we can fully reproduce the trace element enrichment pattern of primitive arc basalts by adding a few percent of saline fluid (with 5–10 wt% Cl) released from the basaltic slab to the zone of melting in the mantle wedge. Assuming 2 wt% of rutile in the eclogite equilibrated with the saline fluid produces a negative Nb Ta anomaly that is larger than in most primitive arc basalts. Therefore, we conclude that the rutile fraction in the subducted eclogite below most arcs is likely < 1 wt%. In fact, saline fluids would even produce a noticeable negative Nb Ta anomaly without any rutile in the eclogite residue. Metasomatism by sediment melts alone, on the other hand, is unable to produce the enrichment pattern seen in arc basalts. We, therefore, conclude that at least for primitive arc basalts, the release of hydrous fluids from the basaltic part of the subducted slab is the trigger for melting and the main agent of trace element enrichment. The contribution of sediment melts to the petrogenesis of these magmas is likely negligible. In the supplementary material, we provide a “Subduction Calculator” in Excel format, which allows the calculation of the trace element abundance pattern in primitive arc basalts as function of fluid salinity, the amount of fluid released from the basaltic part of the subducted slab, the fluid fraction added to the source, and the degree of melting.

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples

Proteases are regulators of countless physiological processes and the precise investigation of their activities remains an intriguing biomedical challenge. Among the ~600 proteases encoded by the human genome, neutrophil serine proteases (NSPs) are thoroughly investigated for their involvement in the onset and progression of inflammatory conditions including respiratory diseases. Uniquely, secreted NSPs not only diffuse within extracellular fluids but also localize to plasma membranes. During neutrophil extracellular trap (NETs) formation, NSPs become an integral part of the secreted chromatin. Such complex behavior renders the understanding of NSPs pathophysiology a challenging task. Here, detailed protocols are shown to visualize, quantify and discriminate free and membrane-bound neutrophil elastase (NE) and cathepsin G (CG) activities in sputum samples. NE and CG are NSPs whose activities have pleiotropic roles in the pathogenesis of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD): they promote tissue remodeling, regulate downstream immune responses and correlate with lung disease severity. The protocols show how to separate fluid and cellular fraction, as well as the isolation of neutrophils from human sputum for enzymatic activity quantification via small-molecule Förster resonance energy transfer-based (FRET) reporters. To gather specific insights into the relative role of NE and CG activities, a FRET readout can be measured by different technologies: i) in vitro plate reader measurements allow for high-throughput and bulk detection of protease activity; ii) confocal microscopy spatiotemporally resolves membrane-bound activity at the cell surface; iii) small-molecule FRET flow cytometry enables for the rapid evaluation of anti-inflammatory treatments via single-cell protease activity quantification and phenotyping. The implementation of such methods opens the doors to explore NSPs pathobiology and their potential as biomarkers of disease severity for CF and COPD. Given their standardization potential, their robust readout and simplicity of transfer, the described techniques are immediately shareable for implementation across research and diagnostic laboratories.

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples.

Proteases are regulators of countless physiological processes and the precise investigation of their activities remains an intriguing biomedical challenge. Among the ~600 proteases encoded by the human genome, neutrophil serine proteases (NSPs) are thoroughly investigated for their involvement in the onset and progression of inflammatory conditions including respiratory diseases. Uniquely, secreted NSPs not only diffuse within extracellular fluids but also localize to plasma membranes. During neutrophil extracellular trap (NETs) formation, NSPs become an integral part of the secreted chromatin. Such complex behavior renders the understanding of NSPs pathophysiology a challenging task. Here, detailed protocols are shown to visualize, quantify and discriminate free and membrane-bound neutrophil elastase (NE) and cathepsin G (CG) activities in sputum samples. NE and CG are NSPs whose activities have pleiotropic roles in the pathogenesis of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD): they promote tissue remodeling, regulate downstream immune responses and correlate with lung disease severity. The protocols show how to separate fluid and cellular fraction, as well as the isolation of neutrophils from human sputum for enzymatic activity quantification via small-molecule Förster resonance energy transfer-based (FRET) reporters. To gather specific insights into the relative role of NE and CG activities, a FRET readout can be measured by different technologies: i) in vitro plate reader measurements allow for high-throughput and bulk detection of protease activity; ii) confocal microscopy spatiotemporally resolves membrane-bound activity at the cell surface; iii) small-molecule FRET flow cytometry enables for the rapid evaluation of anti-inflammatory treatments via single-cell protease activity quantification and phenotyping. The implementation of such methods opens the doors to explore NSPs pathobiology and their potential as biomarkers of disease severity for CF and COPD. Given their standardization potential, their robust readout and simplicity of transfer, the described techniques are immediately shareable for implementation across research and diagnostic laboratories.

Posible differential diagnosis of various chronic nonbacterial prostatites

Background: The purpose of the study was to diagnose possible chronic nonbacterial prostatitis (CNP) and chronic pelvic pain syndrome (CPPS) among patients, as well as differentiate between the inflammatory (category IIIA) or non-inflammatory (category IIIB) types in selecting and optimizing differential drug treatment of this category of patients. Material and methods: The study was conducted on 43 patients diagnosed with CNP/CPPS. The control group included 10 healthy men. Both the production of nitric oxides (NO) by phagocytes, as well as prostate secretion and ejaculate were determined according to the procedure described by Metelyskaya B.A., which was modified by Gudumac V, et al. Results: There was a 39.0% (p &lt;0. 05) decrease in NO production by induced NO-synthase (iNOS), determined in the blood of 11 patients (from the main group – 2) with CNP/CPPS and a 115% (p &lt;0.05) increase was determined in 32 patients (from the main group 1) if compared to the same indices in the control group. The prostatic secretion and ejaculate showed a higher macrophage iNOS activity by 80% (p &lt;0.05) and 75% (p &lt;0.05) if compared to the same parameters from the control group. The iNOS activity in prostatic fluid and split-ejaculate fractions from the main group – 2 did not differ from that of the control group. Conclusions: The assessment of NO production, prostate secretion and ejaculate allows to somewhat establish the main diagnosis of CNP and category III types (A – inflammatory and B – non-inflammatory prostatitis), which will significantly contribute to the optimization and selection of an appropriate differential treatment based on the drug action mechanisms

Molecular diagnosis of SARS-CoV-2 in seminal fluid

PurposeDue to relevant repercussions on reproductive medicine, we aimed to evaluate feasibility of RT-PCR as a detection method of SARS-CoV-2 RNA in seminal fluid.MethodsA qualitative determination of the RT-PCR assays in semen was performed through different approaches: (1) efficiency of RNA extraction from sperm and seminal plasma was determined using PRM1 and PRM2 mRNA and a heterologous system as control; (2) samples obtained by diluting viral preparation from a SARS-CoV-2 panel (virus cultured in Vero E6 cell lines) were tested; (3) viral presence in different fractions of seminal fluid (whole sample, seminal plasma and post-centrifugation pellet) was evaluated. Semen samples from mild and recovered COVID-19 subjects were collected by patients referring to the Infectious Disease Department of the Policlinico Umberto I Hospital - “Sapienza” University of Rome. Control subjects were recruited at the Laboratory of Seminology-Sperm Bank “Loredana Gandini'' of the same hospital.ResultsThe control panel using viral preparations diluted in saline and seminal fluid showed the capability to detect viral RNA presence with Ct values depending on the initial viral concentration. All tested semen samples were negative for SARS-CoV-2, regardless of the nasopharyngeal swab result or seminal fluid fraction.ConclusionThese preliminary data show that RT-PCR for SARS-CoV-2 RNA testing appears to be a feasible method for the molecular diagnosis of SARS-CoV-2 in seminal fluid, supported by results of the control panel. The ability to detect SARS-CoV-2 in semen is extremely important for reproductive medicine, especially in assisted reproductive technology and sperm cryopreservation.

Seismic performance of magnetorheological damped structures with different MR fluid perfusion densities of the damper

Performance tests of magnetorheological (MR) dampers show that the hysteresis curves generally show an obvious force–lag phenomenon, which is due to the presence of trapped air in the working chamber of the damper. However, the force–lag phenomenon is barely considered in existing studies, and its influence on the seismic performance of MR damped structures is still unclear. In this paper, experimental and theoretical research have been carried out to analyze the force–lag phenomenon and its influence. Firstly, a specially designed MR damper was manufactured so that MR fluid can be poured into the damper successively for several times until the working chamber was filled, and performance tests were carried out correspondingly with different MR fluid perfusion densities (a parameter introduced in this paper to describe the volume fraction of MR fluid in the working chamber). The mechanical properties of the MR damper under different MR fluid perfusion densities were compared to reveal the influence of the force–lag phenomenon. Then, the effects of excitation properties on the force–lag phenomenon were discussed by comparing experiments results under different currents, frequencies and displacement amplitudes. Further, a force–lag mathematical model was proposed by considering the variation of the force-lag part with MR fluid perfusion density to reflect the force–lag phenomenon with different volume fractions of trapped air, and then verified based on the performance test data. Finally, numerical analysis of MR damped structures with different MR fluid perfusion densities was performed using the proposed force–lag mathematical model. Results show that the damping effect of MR control systems will be weaken due to the force–lag phenomenon, and with the increase of the MR fluid perfusion density, the seismic performance of MR damped structures will gradually improve.

Electrical Conductivity in Texturally Equilibrated Fluid‐Bearing Forsterite Aggregates at 800°C and 1 GPa: Implications for the High Electrical Conductivity Anomalies in Mantle Wedges

AbstractAqueous fluids are one of the principal agents of chemical transport in Earth´s interior. The precise determination of fluid fractions is essential to understand bulk physical properties, such as rheology and permeability, and the geophysical state of the mantle. Laboratory‐based electrical conductivity measurements are an effective method for estimating the fluid distribution and fraction in a fluid‐bearing rock. In this study, the electrical conductivity of texturally equilibrated fluid‐bearing forsterite aggregates was measured for the first time with various fluid fractions at a constant salinity of 5.0 wt.% NaCl at 1 GPa and 800°C. We found that the electrical conductivity nonlinearly increases with increasing fluid fraction, and the data can be well reproduced by the modified Archie's law. The three‐dimensional (3‐D) microstructure of the interstitial pores visualized by the high‐resolution synchrotron X‐ray computed micro‐tomography (CT) shows a change in fluid distribution from isolated pockets at a fluid fraction of 0.51 vol.% to interconnected networks at fluid fractions of 2.14 vol.% and above due to grain anisotropy and grain size differences, accounting for the nonlinear increase in electrical conductivity. The rapid increase in conductivity indicates that there is a threshold fluid fraction between 0.51 and 2.14 vol.% for forming interconnected fluid networks, which is consistent with the 3‐D images. Our results provide direct evidence that the presence of &gt;1.0 vol.% aqueous fluid with 5.0 wt.% NaCl is required to explain the high conductivity anomalies above 0.01 S/m detected in deep fore‐arc mantle wedges.