Saturable Process Research Articles

Saturation and periodic self-stress in geometric auxetics

The auxetic structures considered in this paper are three-dimensional periodic bar-and-joint frameworks. We start with the specific purpose of obtaining an auxetic design with underlying periodic graph of low valency. Adapting a general methodology, we produce an initial framework with valency seven and one degree of freedom. Then, we describe a saturation process, whereby edge orbits are added up to valency 16, with no alteration of the deformation path. This is reflected in a large dimension for the space of periodic self-stresses. The saturated version has higher crystallographic symmetry and allows a precise description of the deformation trajectory. Reducing saturation by adequate removal of edge orbits results in vast numbers of distinct auxetic designs which obey the same kinematics.

Systematic study of critical parameters on magnesium saturated thiosulfate gold leaching process; part A: Effect of ammonia and lime for pH adjustments and concentration of magnesium and copper(II)

Thiosulfate gold leaching is an alternative gold leaching method, especially for leaching of preg-robbing gold ores. Here we report a thiosulfate process that has been developed for gold leaching, with emphasis on lowering thiosulfate consumption in the process. Ammonium thiosulfate has been used as the primary lixiviant along with magnesium hydroxide to saturate the solution with magnesium in the presence of copper(II) as an oxidizing agent. The resulting magnesium thiosulfate solution (Mg-TS) can potentially leach gold from the ore at considerably high efficiency. The potential for substantial decrease in the thiosulfate consumption, while achieving high gold recovery, gives the Mg-TS process a cutting-edge advantage over other processes. The study demonstrates the effect of pH, magnesium, and initial Cu(II) concentration on gold leaching kinetics in the Mg-TS process. As a comparison, pH of the tests was controlled with Ca(OH)2 and NH4OH; it was concluded that high pH, if controlled by NH4OH, is beneficial for gold leaching due to increase in ligand (NH3) availability and favorable pH range. Increasing pH using Ca(OH)2 was only effective up to a pH threshold of 9.8, after which the efficiency of the process decreases due to the precipitation of Cu(II) catalyst/oxidant. Increasing copper(II) concentration to 8 mM leached 87.8% of gold which was very close to the gold recovery with cyanidation (87.3%). The Mg-TS process identified is an operationally green and sustainable, efficient and low-cost thiosulfate process, which is feasible for in-situ/heap leaching of low-grade gold ores and is believed to present a competitive advantage over cyanidation process.

We Story: Decoloniality in Practice and Theory

Western research and education draw heavily on evidence-based approaches underpinned by positivism. Reliance on this scientific approach informs what is to be counted, measured, and tested—what can be “known.” In our experience, evidence generated using this approach does not always bring the most useful outcomes in our diverse, naturalistic settings. In fact, often the proffered solution can distance and dehumanize the very people expected to be beneficiaries. In this article, we, as researchers and educators from different cultural and professional backgrounds in the “post-colonial” South Pacific, pose an alternative to this Western approach. We engage in a story saturated process akin to collaborative auto-ethnography. We first undertake a process of owning our stories, critically reflecting upon ourselves and how we approach evidence. In the context of values-driven, dialogical relationships, we experiment with intersectionality, interdisciplinarity, and experiences of time and space to critically explore our practice and experience of decoloniality and transformation. Then, through sharing our stories, we critically reflect upon creative, culturally relevant practices. These stories include using poetry in social work education and health research, cake art, and social work storytelling. We acknowledge cultural story forms, collaboration, and performance in a higher education setting. These experiences lead to creating new stories. We share examples of change; we “talk up” to and challenge rationalist, evidence-based approaches in our respective professional spaces. We examine relationality and Indigenous epistemology underpinning our use of story. We present the power of story as a process of transformation toward decoloniality of theory and practice.

Effect of propylene in feedstock on the coking behavior of PtSnK/Al2O3 catalyst of propane dehydrogenation

The dehydrogenation of propane was carried out with feed gas containing different proportions of propylene, and the coking behavior of Pt-based catalyst under propene-rich condition was investigated. The results show that the presence of propylene in the raw material accelerates the rate of coke deposition, shortens the time of dynamic equilibrium of coke deposition on the support, and promotes the formation of coke on the surface area of the active phase and the subsequent graphitization. At the same time, the increase the amount of unsaturated aliphatic compounds, thus promoting the generation of aromatic carbon and graphitized carbon, while the catalyst structure is not destroyed. In the process of propane dehydrogenation, the coke “Peak I” appears on the surface of the active phase, and the “Peak II” moves to the high-temperature region, when the propylene content increase to 1.5%. With the alkene content increasing to 3.0%, Peak I and Peak II merge into a larger peak, the area of which increases significantly. When the coke content exceeds 10.26%, the graphitization degree of the catalyst becomes higher and higher. The increase of the propylene content accelerates the saturation process of the coke holding capacity of the carrier, meaning the increasing amount of coke deposit under the same reaction time.

The Efficient and Convenient Extracting Uranium from Water by a Uranyl-Ion Affine Microgel Container.

Uranium is an indispensable part of the nuclear industry that benefits us, but its consequent pollution of water bodies also makes a far-reaching impact on human society. The rapid, efficient and convenient extraction of uranium from water is to be a top priority. Thanks to the super hydrophilic and fast adsorption rate of microgel, it has been the ideal adsorbent in water; however, it was too difficult to recover the microgel after adsorption, which limited its practical applications. Here, we developed a uranyl-ion affine and recyclable microgel container that has not only the rapid swelling rate of microgel particles but also allows the detection of the adsorption saturation process by the naked eye.

Numerical simulation of saturated oil process based on digital pore model

In order to study the saturated oil process in the digital pore model, numerical simulations are performed by building a model. The results show that the direction of the capillary force is judged according to whether there is an odd or even number of fluid segments in the throat, and the odd segments cancel each other out, while the even segments have a capillary force; Three cases need to be considered when calculating the drag coefficient: (1) only single-phase fluid exists in the throat; (2) the corner of the throat is in the wetted phase, while the center of the throat is in the non-wetted phase; (3) the corner is in the wetted phase and the center of the throat is a multi-phase fluid. After performing saturated oil simulation calculations, the digital pore model can visualize the saturated oil process and results, which is realistic, fast, accurate and low cost, and is of great significance to the subsequent research on efficient reservoir development methods.

Characteristics of Resilient Modulus of Weathered Phyllite Subgrade during Saturation Process

Characteristics of Resilient Modulus of Weathered Phyllite Subgrade during Saturation Process

A modified Kozeny–Carman equation for predicting saturated hydraulic conductivity of compacted bentonite in confined condition

Kozeny–Carman (KC) equation is a well-known relation between hydraulic conductivity and pore properties in porous material. The applications of KC equation to predicting saturated hydraulic conductivities of sands and non-expansive soils are well documented. However, KC equation is incapable of predicting saturated hydraulic conductivity of expansive soil (e.g. bentonite) well. Based on a new dual-pore system, this study modified KC equation for improving the prediction of saturated hydraulic conductivities of bentonites. In this study, an assumption that inter-layer space (micropore) has limited effect on fluid flow performance of compacted bentonite was adopted. The critical parameters including total porosity and total tortuosity in conventional KC equation were replaced by macroporosity and tortuosity of macropore, respectively. Macroporosity and microporosity were calculated by basal spacing of compacted bentonite, which was estimated by assuming that specific surface area is changeable during saturation process. A comprehensive comparison of bentonite's saturated hydraulic conductivity predictions, including modified KC equation proposed in this study, conventional KC equation, and prediction method based on diffuse double layer (DDL) theory, was carried out. It was found that the predicted saturated hydraulic conductivity of bentonites calculated using modified KC equation fitted the experimental data better than others to a certain extent.

Does the cytokine adsorber CytoSorb® reduce vancomycin exposure in critically ill patients with sepsis or septic shock? a prospective observational study

BackgroundHemadsorption of cytokines is used in critically ill patients with sepsis or septic shock. Concerns have been raised that the cytokine adsorber CytoSorb® unintentionally adsorbs vancomycin. This study aimed to quantify vancomycin elimination by CytoSorb®.MethodsCritically ill patients with sepsis or septic shock receiving continuous renal replacement therapy and CytoSorb® treatment during a prospective observational study were included in the analysis. Vancomycin pharmacokinetics was characterized using population pharmacokinetic modeling. Adsorption of vancomycin by the CytoSorb® was investigated as linear or saturable process. The final model was used to derive dosing recommendations based on stochastic simulations.Results20 CytoSorb® treatments in 7 patients (160 serum samples/24 during CytoSorb®-treatment, all continuous infusion) were included in the study. A classical one-compartment model, including effluent flow rate of the continuous hemodialysis as linear covariate on clearance, best described the measured concentrations (without CytoSorb®). Significant adsorption with a linear decrease during CytoSorb® treatment was identified (p < 0.0001) and revealed a maximum increase in vancomycin clearance of 291% (initially after CytoSorb® installation) and a maximum adsorption capacity of 572 mg. For a representative patient of our cohort a reduction of the area under the curve (AUC) by 93 mg/L*24 h during CytoSorb® treatment was observed. The additional administration of 500 mg vancomycin over 2 h during CytoSorb® attenuated the effect and revealed a negligible reduction of the AUC by 4 mg/L*24 h.ConclusionWe recommend the infusion of 500 mg vancomycin over 2 h during CytoSorb® treatment to avoid subtherapeutic concentrations.Trial registration NCT03985605. Registered 14 June 2019, https://clinicaltrials.gov/ct2/show/NCT03985605

MATHEMATICAL MODEL OF GRAIN RAW MOVEMENT IN INTERACTION WITH DISPERSER AND SCREW FEEDER

Bioactivated dispersed grain, which is obtained by soaking followed by grinding on a dispersant is a promising raw material for expanding the range of bakery products and providing the population with products of high biological value. Bioactivation is understood as the process of grain saturation with moisture, during which the transformation of macromolecular substances into easily accessible forms takes place, which makes it a source of bioactive substances. However, the implementation of the process of dispersing bioactivated grain material remains relevant, the process of grinding which is mainly influenced by such factors as moving the grain with the help of a screw feeder and pushing it through the cutting mechanism. To obtain dispersed grain, there are a large number of crushing machines, the main working bodies of which are the screw feeder, knives and lattice. Many scientific papers are devoted to improving the helical transport mechanism of the disperser, by changing its design, which allows to increase the homogeneity of the grain mass at the outlet, its dispersion, reduce energy consumption and increase productivity. However, the use of screw feeders for grain dispersion raises a number of issues that require further research. Namely, the study of the influence of the additional pressure required to work when loading the material on the process of its movement, and determining the speed of movement of the grain material through the cutting mechanism for grinding in the dispersant. To address the above issues, a mathematical model for the movement of grain raw materials during grinding is proposed. Mathematical dependences for determining the speed of the dispersing process have been obtained, which can be applied taking into account the physical properties of the material in the stationary mode of operation of the dispersant.

Generalized network modelling of two-phase flow in a water-wet and mixed-wet reservoir sandstone: Uncertainty and validation with experimental data

We use a generalized pore network model in combination with image-based experiments to understand the parameters that control upscaled flow properties. The study is focued on water-flooding through a reservoir sandstone under water-wet and mixed-wet conditions. A set of sensitivity studies is presented to quantify the role of wettability, pore geometry, initial and boundary conditions as well as a selection of model parameters used in the computation of fluid volumes, curvatures and flow and electrical conductivities.We quantify the uncertainty in the model predictions, which match the measured relative permeability and capillary pressure within the uncertainty of the experiments. Our results show that contact angle, initial saturation, image quality and image processing algorithm are amongst the parameters which introduce the largest variance in the predictions of upscaled flow properties for both mixed-wet and water-wet conditions.

Heat and mass transfer and hydrodynamics in cryogenic hydrogen fuel systems

The paper presents the results of experimental and theoretical studies and the development of methods to calculate the parameters of heat and mass transfer as well as hydrodynamic processes occurring during the following operations: filling of reservoirs and tanks with LH2; drain-free storage of LH2; saturation of LH2 with non-condensable gas (helium) during tank pressurization; drainage of hydrogen vapors and displacement of LH2 from the storage tank. It is noted that the main design parameters characterizing the process of filling cryogenic reservoirs and tanks are the following: the time of filling to the required level; LH2 evaporation losses during cooling; thermal stresses in the walls of reservoirs and tanks. The time of LH2 drain-free storage in real reservoirs and tanks is reduced due to thermal stratification in the liquid and gas–vapor phases compared to the time of LH2 drain-free storage under conditions of its complete mixing. The drainage of LH2 vapors is characterized by the following main design parameters: the rate of pressure change in the cryogenic tank; the flow rate of the drained mass; the degree of non-equilibrium during LH2 boiling; drop entrainment; an increase in the LH2 volume during boiling (“swelling”); the degree of pressure increase in case of a sudden termination of drainage. When LH2 is displaced, the following parameters of the feed system have a decisive influence on the heat and mass transfer characteristics: displacement pressure; LH2 thermal stratification; the degree of LH2 saturation with non-condensable gas; the maximum temperature of the tank wall; the mass of pressurizing gas. Liquid hydrogen (LH2) can be saturated during pressurization and displacement with helium and during other operations involving the use of non-condensable gas. The process of LH2 saturation with pressurizing gas (helium) is characterized by the following parameters: absorption coefficient that determines the efficiency of gas saturation and is equal to the ratio of the dissolved amount of helium to the entire mass of non-condensable gas that has passed through the solution; change in the LH2 temperature during gas saturation; helium concentration in the solution and its homogeneity. Based on the obtained experimental data and mathematical modeling, we determined relationships that make it possible to calculate the listed main parameters of heat and mass transfer as well as hydrodynamic processes at the main stages of the design and operation of cryogenic hydrogen tanks, systems of LH2 storage and feeding. The presented relationships can be used as reference data in the design and optimization of LH2 fuel systems.

Contact tracing-induced Allee effect in disease dynamics

Contact tracing, case isolation, quarantine, social distancing, and other non-pharmaceutical interventions (NPIs) have been a cornerstone in managing the COVID-19 pandemic. However, their effects on disease dynamics are not fully understood. Saturation of contact tracing caused by the increase of infected individuals has been recognized as a crucial variable by healthcare systems worldwide. Here, we model this saturation process with a mechanistic and a phenomenological model and show that it induces an Allee effect which could determine an infection threshold between two alternative states—containment and outbreak. This transition was considered elsewhere as a response to the strength of NPIs, but here we show that they may be also determined by the number of infected individuals. As a consequence, timing of NPIs implementation and relaxation after containment is critical to their effectiveness. Containment strategies such as vaccination or mobility restriction may interact with contact tracing-induced Allee effect. Each strategy in isolation tends to show diminishing returns, with a less than proportional effect of the intervention on disease containment. However, when combined, their suppressing potential is enhanced. Relaxation of NPIs after disease containment--e.g. because vaccination--have to be performed in attention to avoid crossing the infection threshold required to a novel outbreak. The recognition of a contact tracing-induced Allee effect, its interaction with other NPIs and vaccination, and the existence of tipping points contributes to the understanding of several features of disease dynamics and its response to containment interventions. This knowledge may be of relevance for explaining the dynamics of diseases in different regions and, more importantly, as input for guiding the use of NPIs, vaccination campaigns, and its combination for the management of epidemic outbreaks.

Bimodal polymorphic nanodomains in ferroelectric films for giant energy storage

Enhanced functional responses of ferroelectrics have often been achieved by complex compositional design of a morphotropic or polymorphic phase boundary. Here, we observe a pseudo-linear, ultra-slim polarization-electric field (P-E) hysteresis loop in simple composition, lead-free Ba(Zr,Ti)O3 of up to μm-thick. It features a low remnant polarization and a high maximum polarization after a delayed saturation process with a field-insensitive, thickness-scalable high energy efficiency of ∼90%. This giant energy storage performance is attributed to the self-assembled, bimodal polymorphic nanodomains consisting of two sets of coherent polymorphic nanodomains. The first set of domains has the best-matched, low index {110} interface. They manifest themselves as “entangled nanophases” and dominate in thinner or annealed films. The 2nd set of domains with a high-index {114} interface and an in-plane anisotropy leads to the largest reduction in bulk elastic energy. These domains show as “segregated nanophases” and prevail in as-grown thick films. The presence of multi-polar states in both sets of nanodomains helps reduce the remnant polarization and delay the polarization saturation. Furthermore, the segregated tetragonal phase in-plane nanodomains lead to a larger maximum polarization under a high poling field. Strain engineering of such nanodomain structures provides a promising alternative to chemical compositional design, for the optimization of dielectric thin films used in capacitive energy storage applications.

Exploring Dried Blood Spot Cortisol Concentrations as an Alternative for Monitoring Pediatric Adrenal Insufficiency Patients: A Model-Based Analysis.

Congenital adrenal hyperplasia (CAH) is the most common form of adrenal insufficiency in childhood; it requires cortisol replacement therapy with hydrocortisone (HC, synthetic cortisol) from birth and therapy monitoring for successful treatment. In children, the less invasive dried blood spot (DBS) sampling with whole blood including red blood cells (RBCs) provides an advantageous alternative to plasma sampling. Potential differences in binding/association processes between plasma and DBS however need to be considered to correctly interpret DBS measurements for therapy monitoring. While capillary DBS samples would be used in clinical practice, venous cortisol DBS samples from children with adrenal insufficiency were analyzed due to data availability and to directly compare and thus understand potential differences between venous DBS and plasma. A previously published HC plasma pharmacokinetic (PK) model was extended by leveraging these DBS concentrations. In addition to previously characterized binding of cortisol to albumin (linear process) and corticosteroid-binding globulin (CBG; saturable process), DBS data enabled the characterization of a linear cortisol association with RBCs, and thereby providing a quantitative link between DBS and plasma cortisol concentrations. The ratio between the observed cortisol plasma and DBS concentrations varies highly from 2 to 8. Deterministic simulations of the different cortisol binding/association fractions demonstrated that with higher blood cortisol concentrations, saturation of cortisol binding to CBG was observed, leading to an increase in all other cortisol binding fractions. In conclusion, a mathematical PK model was developed which links DBS measurements to plasma exposure and thus allows for quantitative interpretation of measurements of DBS samples.

Marginal and joint failure importance for K-terminal network edges under counting process

Importance measures have been applied extensively in various fields such as reliability optimization, failure diagnosis, and risk analysis. Traditional importance measures are insufficient for networks because they only quantify the contribution of each edge's reliability to network reliability. The counting process is a kind of stochastic process that can count the number of edge failures appeared in a time of period, which requires less information than knowing all edge reliabilities. In the context of edge failures subject to a counting process, this paper investigates importance measures for a given binary K-terminal network including n binary edges. This paper develops some formulas to compute the joint failure importance (JFI) and the marginal failure importance (MFI). The MFI quantifies the changes of network failure probability caused by the change of edge state, while the JFI evaluates the interaction effect between two edges regarding network failure probability. Their values, as functions of time t, depend on the probability distribution of the total number of edge failures at time t and the network structure. Additionally, we present a Monte-Carlo algorithm to approximate the values of the MFI and JFI. Finally, a numerical example concerning the road network is provided to demonstrate the computation methods of MFI and JFI, whose edge failures are subject to a saturated nonhomogeneous Poisson process. The numerical results provide further insights for the road network regarding the importance of edges.

Environmental Assessment of Emissions of Pollutants into the Atmospheric Air by Sugar Beet Factories

The results of environmental assessment of emissions of pollutants (pollutants), greenhouse gas CO2 and odor emissions from sugar factories into the air are presented. The discrepancy in the interpretation of industrial environmental control on the basis of the concept of the best available technologies (BAT) for the technological line of sugar production and the requirements of environmental legislation for a sugar plant as an anthropogenic object of monitoring is shown. To achieve the effect of reducing the emission of carbon dioxide into the atmosphere, twostage saturation of defecation juice was studied using jet technology. Various options of hardware design for the practical implementation of the injection process of saturation have been proposed.

Influence of Reduction Temperature on the Structure and Naphthalene Hydrogenation Saturation Performance of Ni2P/Al2O3 Catalysts

Jet fuel rich in hydroaromatics and cycloalkanes could be derived from direct coal liquefaction oil via the hydrogenation saturation process. Developing an efficient catalyst to transform naphthalene hydrocarbons to hydroaromatics and cycloalkanes with high selectivity plays a significant role in realizing the above hydrogenation saturation process. In this work, Ni2P/Al2O3 catalysts were prepared at different reduction temperatures via the thermal decomposition of hypophosphite. We investigated the influence of reduction temperature and the results showed that reduction temperature had an important impact on the properties of Ni2P/Al2O3 catalysts. When the reduction temperature was 400 °C, the Ni2P particle size of the Ni2P/Al2O3 catalyst was 3.8 nm and its specific surface area was 170 m2/g. Furthermore, the Ni2P/Al2O3 catalyst reduced at 400 °C obtained 98% naphthalene conversion and 98% decalin selectivity. The superior catalytic activity was attributed to the smaller Ni2P particle size, higher specific surface area and suitable acidity, which enhanced the adsorption of naphthalene on Ni2P/Al2O3 catalyst.

Fractional-order sliding mode control with a predefined-time observer for VTVL reusable launch vehicles under actuator faults and saturation constraints

For vertical takeoff vertical landing (VTVL) reusable launch vehicle (RLV) with actuator faults and saturation constraints, this paper presents a composite control system including a high-order predefined-time extended state observer (HO-PTESO), a predefined-time anti-saturation compensator (PTASC), and a fractional-order practical predefined-time sliding mode control law (FO-PPTSMC). The HO-PTESO accomplishes the precise estimation of disturbance in a time interval predefined by only one design parameter, resulting in a simple and weakly conservative parameter tuning process for temporal demands. Moreover, the peaking value problem is well addressed. The PTASC serves to ensure the stability of the saturated system. Auxiliary variables of the PTASC remain bounded during the saturation process and vanish within the predefined time interval after the saturation process ends, avoiding long-term impacts on the attitude tracking that are common concerns for existing ASCs. Using the estimated disturbance, the FO-PPTSMC enforces unsaturated system states to a predefined residual set of the origin in a chattering-alleviated manner within the predefined time interval. Two parameters respectively predefine the convergence range and time, resulting in a considerably simplified synthesis procedure. Ultimately, numerical simulations on the double integrator system and VTVL RLV model validate the efficiency of the proposed control system.

Approaching the Attosecond Frontier of Dynamics in Matter with the Concept of X-ray Chronoscopy

X-ray free electron lasers (XFELs) have provided scientists opportunities to study matter with unprecedented temporal and spatial resolutions. However, access to the attosecond domain (i.e., below 1 femtosecond) remains elusive. Herein, a time-dependent experimental concept is theorized, allowing us to track ultrafast processes in matter with sub-fs resolution. The proposed X-ray chronoscopy approach exploits the state-of-the-art developments in terahertz streaking to measure the time structure of X-ray pulses with ultrahigh temporal resolution. The sub-femtosecond dynamics of the saturable X-ray absorption process is simulated. The employed rate equation model confirms that the X-ray-induced mechanisms leading to X-ray transparency can be probed via measurement of an X-ray pulse time structure.