Full Separation Research Articles

Relaxation of the Boussinesq system and applications to the Rayleigh\u2013Taylor instability

We consider the evolution of two incompressible fluids with homogeneous densities rho _{-}<rho _+ subject to gravity described by the inviscid Boussinesq equations and provide the explicit relaxation of the associated differential inclusion. The existence of a subsolution to the relaxation allows one to conclude the existence of turbulently mixing solutions to the original Boussinesq system. As a specific application we investigate subsolutions emanating from the classical Rayleigh-Taylor initial configuration where the two fluids are separated by a horizontal interface with the heavier fluid being on top of the lighter. It turns out that among all self-similar subsolutions the criterion of maximal initial energy dissipation selects a linear density profile and a quadratic growth of the mixing zone. The subsolution selected this way can be extended in an admissible way to exist for all times. We provide two possible extensions with different long-time limits. The first one corresponds to a total mixture of the two fluids, the second corresponds to a full separation with the lighter fluid on top of the heavier. There is no motion in either of the limit states.

Developmental dynamics is revealed in the early Cambrian arthropod Chuandianella ovata

SummarySegmentation and tagmatization have contributed to the preeminent success of arthropods since their first appearance in the Cambrian. However, the exact mechanism of segmentogenesis is still insufficiently known in living and extinct groups. Here, we describe the postembryonic development of a Waptiid arthropod Chuandianella ovata from the early Cambrian Chengjiang biota, South China. The new data illuminate a complex dynamic pattern of anamorphosis and epimorphosis, and a three-step process of segmentogenesis, i.e., the elongation of the terminal segment, delineation of an incipient segment, and full separation of a new segment. Compensatory growth is accomplished by rapid growth of new segments and/or generation of additional segments, which results in the trimorphism of the posterior tagma. Such complex developmental dynamics has rarely been known in the arthropod fossil record and its presence in early history helps to understand the rapid diversification of arthropods in the early Cambrian.

Development and validation of a rapid LC\u2013MS/MS method for the confirmatory analysis of the bound residues of eight nitrofuran drugs in meat using microwave reaction

A rapid analytical method was developed and validated for the analysis of eight bound nitrofurans in animal tissue, shortening laboratory turnaround times from 4 to 2 days. The majority of methodologies for nitrofuran analysis focus on the detection of only four drugs (nitrofurantoin, furazolidone, furaltadone and nitrofurazone), and is time-consuming given the 16-h overnight derivatisation step and a double liquid–liquid extraction. In this study, the narrow scope of analysis was addressed by including further four important nitrofuran drugs (nifursol, nitrofuroxazide, nifuraldezone and nitrovin). Full chromatographic separation was achieved for the metabolites of all eight nitrofurans, using phenyl-hexyl column chemistry and a rigorous optimisation of the mobile phase additives and gradient profile. The conventional, lengthy sample preparation was substantially shortened by replacing the traditional overnight water bath derivatisation with a rapid 2-h microwave-assisted reaction, followed by a modified-QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction. This confirmatory method was fully validated in accordance with the new 2021/808/EC legislation, and was shown to perform satisfactorily when applied to incurred tissues. The decision limit (CCα) for the eight analytes ranged between 0.013 and 0.200 µg kg−1, showing abundant sensitivity given that the current RPA for nitrofurans is 0.5 µg kg−1. This innovative method can play a major role in the surveillance of the illegal use of nitrofuran drugs.

A Fundamental Economic Assessment of Recovering Rare Earth Elements and Critical Minerals from Acid Mine Drainage Using a Network Sourcing Strategy

In recent years, acid mine drainage (AMD) has emerged as a promising unconventional source of rare earth elements (REEs) and other critical minerals (CMs) such as cobalt and manganese. In this regard, AMD provides a natural heap leaching effect that extracts and concentrates REE/CM from the host strata creating a partially enriched feedstock suitable for downstream extraction, separation, and recovery. While several prior studies have described processes and approaches for the valorization of AMD, very few have described the supply chain and infrastructure requirements as well as the associated economic assessment. To that end, this paper provides a fundamental economic assessment of REE/CM recovery from AMD using a network sourcing strategy in addition to a robust, flexible feedstock separations and refining facility. The methodology of this paper follows that of a typical techno-economic analysis with capital and operating costs estimated using AACE Class IV (FEL-2) guidelines. To demonstrate the range of possible outcomes, four pricing scenarios were modeled including contemporary prices (September, 2021) as well as the minimum and maximum prices over the last decade. In addition, five production scenarios were considered reflecting variations in the product suite, ranging from full elemental separation to magnet REE and CM production only (i.e., Pr, Nd, Tb, Dy, Y, Sc, Co, and Mn). The results of this analysis show that, with the exception of the minimum price scenario, all operational configurations have positive economic indicators with rates of return varying from 25% to 32% for the contemporary price scenario. The optimal configuration was determined to be production of Co, Mn, and all REEs except for mischmetal, which is not recovered. Sensitivity analysis and Monte Carlo simulation show that capital cost and HCl consumption are the two major factors influencing rate of return, thus indicating opportunities for future technology development and cost optimization. Implications of the study and a cooperative profit-sharing model for sourcing are also described.

Vaginal Cuff Dehiscence: Tips for Laparoscopic Repair and Prevention

<h3>Study Objective</h3> To define vaginal cuff dehiscence, identify risk factors for dehiscence, understand steps needed for laparoscopic cuff revision, and review techniques for cuff closure. <h3>Design</h3> Vaginal cuff dehiscence, defined as a full thickness separation of the vaginal cuff, is a rare but morbid complication after hysterectomy. After a total laparoscopic hysterectomy, the incidence of vaginal cuff dehiscence is 0.7% (range 0.64 – 1.27%). Risk factors include poor vaginal cuff closure technique, smoking, low body mass index, conditions that cause poor wound healing such as infection, hematoma, prior radiation, or immunosuppression, and increased pressure on the vaginal incision line such as trauma, pelvic organ prolapse, or excessive valsalva. In this video we will demonstrate a laparoscopic repair of a vaginal cuff dehiscence. <h3>Setting</h3> Patients should be positioned in lithotomy position in the operating room. Standard GYN laparoscopic setup should be used. The authors prefer placing the camera via a 5mm trocar in the umbilicus, with 2 accessory 5mm ports laterally and a 5mm suprapubic port. <h3>Patients or Participants</h3> N/A. <h3>Interventions</h3> In this video we describe the 5 steps of a laparoscopic repair of a vaginal cuff dehiscence. We also discuss tips and tricks to optimize cuff closure. • Identify and normalize anatomy • Identify the vaginal cuff defect • Mobilize the cuff • Excise cuff edges • Close the cuff <h3>Measurements and Main Results</h3> N/A. <h3>Conclusion</h3> Although vaginal cuff dehiscence is rare, knowledge of safe and effective laparoscopic repair technique is crucial for the gynecologic surgeon, both for repair and for prevention of future cuff dehiscence.

The Effect of Network Formation on Cooperation in the Finitely Repeated Prisoner's Dilemma

We study the effect of network formation on cooperation in the finitely repeated prisoner’s dilemma based on the game-theoretical model approach. We suggest the model explaining the effect of endogenous network formation on cooperation. We find a subgame perfect strongly pairwise-Nash equilibrium in which cooperation is achieved by the trigger strategy based on non-random partner selection. Also, in the subgame perfect strongly pairwise-Nash equilibrium, cooperators are completely connected with other cooperators, and defectors are isolated in the network. These results imply “full separation” of cooperators and defectors in the network and “marginalization” of defectors in the network.

Numerically efficient computation of the survival signature for the reliability analysis of large networks

Societal growth thrives on the performance of critical infrastructure systems such as water supply systems, transportation networks or electrical distribution systems. This makes the reliability analysis of these systems a core focus for researchers today. The survival signature is a novel tool for analysing complex networks efficiently and outperforms traditional techniques in several key factors. Its most unique feature being a full separation of the system structure from probabilistic information. This in turn allows for the consideration of diverse component failure descriptions such as dependencies, common causes of failure and imprecise probabilities. However, the numerical effort to compute the survival signature increases with network size and prevents analysis of complex systems. This work presents a new method to approximate the survival signature, where system configurations of low interest are first excluded using percolation theory, while the remaining parts of the signature are approximated by Monte Carlo simulation. The approach is able to accurately approximate the survival signature with very small error at a massive reduction in computational demands. The accuracy and performance are highlighted using several simple test systems as well as two real world problems.

Enantioselective multiple heart cutting online two-dimensional liquid chromatography-mass spectrometry of all proteinogenic amino acids with second dimension chiral separations in one-minute time scales on a chiral tandem column

In this work, we present a unique, robust and fully automated analytical platform technology for the enantioselective amino acid analysis using a multiple heart cutting RPLC-enantio/stereoselective HPLC-ESI-QTOF-MS method. This 2D-LC method allows the full enantioselective separation of 20 proteinogenic AAs plus 5 isobaric analogues, namely allo-Threonine (aThr), homoserine (Hse), allo-isoleucine (aIle), tert-Leucine (Tle) and Norleucine (Nle), after pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC; AccQ). This N-terminal AA-derivatization method introduces on the one hand beneficial chromatographic properties for 1D RP-LC (stronger retention) and 2D chiral separation (better chiral recognition), and on the other hand favorable detection properties with its chromophoric, fluorophoric, and easily ionizable quinoline mass tag. The entire separation occurs within a total 2DLC run time of 45 min, which includes the 1D-RP run and the 68 s 2D chiral separations of 30 heart-cuts (from the 1D-RP-run) on a chiral quinine carbamate (core-shell QNAX/fully porous ZWIX) tandem column. This relatively short overall run time was only possible by utilizing the highly efficient “smart peak parking” algorithm for the heart cuts and the resulting optimized analysis order thereof. 1D retention time precisions of <0.21% RSD were a requirement for the time-based sampling mode and finally led to a robust, fully automated enantioselective amino acid analysis platform.This achiral-chiral 2DLC method was applied for the amino acid stereoconfiguration assignment of three peptides (aureobasidin A, a lipopeptide research sample, and octreotide) using an L-[u-13C15N] labelled internal AA standard mix spiked to each sample. The isotopically labelled L-AA standard allowed an easy and straightforward identification and configuration assignment, as well as the relative quantification of amino acids within the investigated peptides, allowing the direct determination of the number of respective amino acids and their chirality within a peptide.

Upgrading Octane Number of Naphtha by a Robust and Easily Attainable Metal-Organic Framework through Selective Molecular Sieving of Alkane Isomers.

The separation of alkanes, particularly monobranched and dibranched isomers, is of paramount importance in the petrochemical industry for optimizing the feedstock of ethylene production as well as for upgrading the octane number of gasoline. Here, we report the full separation of linear/monobranched alkanes from their dibranched isomers by a robust and easily scalable metal-organic framework material, Co3 (HCOO)6 . The compound completely excludes dibranched alkanes but adsorbs their linear and monobranched isomers, as evidenced by single-component and multicomponent adsorption measurements. More importantly, the material exhibits excellent performance in separating naphtha and is capable of providing high quality feedstock for the production of ethylene and gasoline components with high octane number, making it a promising candidate for naphtha separation in petrochemical industry.

Three-Dimensional Numerical Investigation of Hypersonic Projectile Launched by Railgun on Transitional Ballistics

Supersonic accelerators use sabots to suppress bore balloting. However, sabot separation induces flight deviation in projectiles owing to their interactions with fluids and shock waves. A seamless calculation of the acceleration phase in the tube and the full separation process using 3-D computational fluid dynamics coupled with rigid body dynamics is presented in this study to investigate the shock-wave interactions around a railgun-launched projectile. The railgun acceleration induced a normal shock wave propagating ahead of the projectile; when the projectile reached the tube end, a substantial expansion at the muzzle generated two shock waves, namely, a spherical precursor shock wave and a Mach disk, outside the tube. Aerodynamic forces on the projectile/sabot decreased to almost zero just after the tube exit, with the ambient fluid around the tube being faster than the projectile by the substantial expansion. After exiting, the projectile penetrated the precursor shock wave at ; this increased the aerodynamic forces acting on the projectile, initiated sabot separation, and generated multiple shock-wave interactions, which induce unsteady aerodynamic loads on the projectile.

Separation of variables in the WZW models

We consider dynamics of scalar and vector fields on gravitational backgrounds of the Wess-Zumino-Witten models. For SO(4) and its cosets, we demonstrate full separation of variables for all fields and find a close analogy with a similar separation of vector equations in the backgrounds of the Myers-Perry black holes. For SO(5) and higher groups separation of variables is found only in some subsectors.

LES study of windward-face-mounted-ribs’ effects on flow fields and aerodynamic forces on a square cylinder

Building-façade-mounted appurtenances are found to be effective for reducing wind loads on high-rise buildings. In this study, large eddy simulations (LES) are performed to investigate the effects of windward-face-mounted ribs on aerodynamic forces acting on a square cylinder of width D under smooth flow. The flow fields, wind pressure distributions and aerodynamic forces on different models are examined to clarify the underlying mechanism of the mitigation of wind load caused by vertical ribs. It is found that local recirculation forms in the front corner region, which greatly influences the flow separation and modifies the behavior of shear-layer flow. Three typical flow patterns around cylinders with different rib depths d are identified: full separation flow (0<d/D ≤ 0.105), periodic attachment flow (0.105<d/D ≤ 0.12), and steady attachment flow (d/D > 0.12). The wake vortex structures, vortex shedding frequency and wind pressure distribution are significantly different under these three flow patterns. The flow field changes result in remarkable mitigation of mean drag C‾d and fluctuating lift C'l. Optimal combinations of location b and depth d of ribs are also investigated. In these optimal cases, the shear layer first separates from the rib's leading edge and then passes by the cylinder's leading edge. The maximum reduction ratios of C‾d and C'l reach 50% and 86%, respectively, when d/D = 0.12 and b/D = 0.10. An empirical configuration equation of the vertical ribs is finally proposed by fitting results of optimal combinations.

Empty and full separation of adeno-associated virus vectors by anion exchange membrane chromatography

Empty and full separation of adeno-associated virus vectors by anion exchange membrane chromatography

The Effects of Adding Reachability Predicates in Quantifier-Free Separation Logic

The list segment predicate ls used in separation logic for verifying programs with pointers is well suited to express properties on singly-linked lists. We study the effects of adding ls to the full quantifier-free separation logic with the separating conjunction and implication, which is motivated by the recent design of new fragments in which all these ingredients are used indifferently and verification tools start to handle the magic wand connective. This is a very natural extension that has not been studied so far. We show that the restriction without the separating implication can be solved in polynomial space by using an appropriate abstraction for memory states, whereas the full extension is shown undecidable by reduction from first-order separation logic. Many variants of the logic and fragments are also investigated from the computational point of view when ls is added, providing numerous results about adding reachability predicates to quantifier-free separation logic.

Mechanistic modeling and CFD simulation of gas chromatography to predict separation processes

Gas chromatography (GC) is a frequently applied separation technique. Nevertheless, a suitable operational setup for reaching separation may require extensive time and resources. Mathematical models have been used to predict chromatographic parameters and to propose the analysis conditions; however, the use of empirical correlations has limited application and may be inaccurate. This work proposed a precise physical-based mathematical model using mechanistic equations to describe GC under constant pressure and constant flow, aiming to predict holdup time and the full separation process in a CFD software. A bidimensional model was validated by the description of the mobile phase flow and compounds elution, allowing to predict the chromatographic parameters in both GC operating modes. The observed errors were less than 5% for all predicted parametric values, which is around the input parameter uncertainty. The 2D approach allowed a relatively quick computational time to describe with high accuracy the evaluated parameters, concentration profile, and an operational setup for separating the compounds.

Unveiling local atomic bonding and packing of amorphous nanophases via independent component analysis facilitated pair distribution function

Amorphous nanophases play a significant role for the properties of a variety of nanoscale heterogeneous materials. Experimental characterization of the atomic arrangement of the amorphous structure, including nanoscale structural variations, is one of the main challenges limiting the rational design of the materials. Here, an approach to characterize local bonding and atomic packing in complex nanomaterials is introduced. Building on scanning transmission electron microscopy (STEM) and pair distribution function analysis (PDF) to record local diffraction information with nanometer spatial resolution, we show that independent component analysis for “blind source separation” of mixed information due to projection effects in STEM-PDF, enables full separation of these signals. The unprecedented information allows determining the structure of individual nanoscale phases and identifying the compounds inside. We analyzed a FeZr/ZrO2 multilayer as proof of principle, and discovered differently coordinated FeOx in the interfacial region. The approach was applied to Fe25Sc75 nanoglass and revealed Fe–Fe bonding concealed in the Sc-rich matrix. Finally, analysis of a shear band in a deformed Cu/CuZr nanolaminate confirmed Cu enrichment and reduced medium-range order in the shear band.

Precipitation in reactor pressure vessel steels under ion and neutron irradiation: On the role of segregated network dislocations

The ultrahigh density of Mn-Ni-Si-Cu precipitates that form in irradiated reactor pressure vessels (RPV) result in hardening and embrittlement, which may limit the service life of aging nuclear reactors. Here, we quantitatively analyze solute segregation to, and precipitation on, network dislocations in irradiated low alloy RPV steels. The analysis is based on a broad thermodynamic framework, which allows proper identification of possible non-equilibrium perturbative effects of irradiation, like radiation induced segregation (RIS). For the first time, we quantify the segregation of Cu, Mn, Ni and Si to ≈ 5–10 nm network dislocation segments, typically separated by a string-of-pearl type array of MnNiSi precipitates (MNSPs); the MNSPs are appended to Cu rich co-precipitates (CRPs) in steels bearing this element. Detailed atom probe tomography (APT) data are reported for 16 RPV steels, with a wide matrix of tailored compositions, irradiated by both neutrons and 6.4 MeV Fe3+ ions at 320 and 290 °C, respectively. A key aspect of this study is that the very high displacement per atom (dpa) doses and radiation enhanced diffusion (RED) result in nearly full phase separation, allowing isolation of thermodynamic (equilibrium or non-equilibrium) effects. We characterize segregation and precipitates with a comprehensive set of descriptors under both ion and neutron irradiation, including: a) solute enrichment factors (EFs) at dislocations, as a function of alloy composition; and, b) matrix versus dislocation precipitates and their respective characteristics. Formation of these dislocation features can be due to RIS, or thermodynamic in origin, or both. Coupled with simple models, we show that the nucleation MNSP features in low Cu steels is enhanced by segregation. However, in typical supersaturated RPV steels, rapid growth of the precipitates is thermodynamically driven to a quantitatively predictable, nearly full phase separation mole fraction.

An Analysis of Portion Cap Rules with a Multiproduct Seller

I study the impacts of limiting the quantity of one product in a two‐goods market with privately informed buyers. The goal is to explore effects on consumer surplus and consumption of both products. The main finding is that following moderate enough caps, a standard nonlinear pricing model predicts an increase in surplus for the buyer with low preference for the regulated good and high valuation for the unregulated product. Specific changes in allocation depend on the model's parameters. Consumption of the limited good is reduced, whereas consumption of the unregulated item often falls. Changes in screening are also interesting. Severe enough caps cause the seller to move from full separation to bunching some types. These results are applicable to food retail and other industries, where portion cap rules are a regulatory alternative and the impact on consumer surplus is an important consideration.

Pressure Orientation-Dependent Recovery of 3D-Printed PLA Objects with Varying Infill Degree.

Poly(lactic acid) is not only one of the most often used materials for 3D printing via fused deposition modeling (FDM), but also a shape-memory polymer. This means that objects printed from PLA can, to a certain extent, be deformed and regenerate their original shape automatically when they are heated to a moderate temperature of about 60–100 °C. It is important to note that pure PLA cannot restore broken bonds, so that it is necessary to find structures which can take up large forces by deformation without full breaks. Here we report on the continuation of previous tests on 3D-printed cubes with different infill patterns and degrees, now investigating the influence of the orientation of the applied pressure on the recovery properties. We find that for the applied gyroid pattern, indentation on the front parallel to the layers gives the worst recovery due to nearly full layer separation, while indentation on the front perpendicular to the layers or diagonal gives significantly better results. Pressing from the top, either diagonal or parallel to an edge, interestingly leads to a different residual strain than pressing from front, with indentation on top always firstly leading to an expansion towards the indenter after the first few quasi-static load tests. To quantitatively evaluate these results, new measures are suggested which could be adopted by other groups working on shape-memory polymers.

Anion-exchange HPLC assay for separation and quantification of empty and full capsids in multiple adeno-associated virus serotypes

Gene therapy has entered a new era where numerous therapies for severe and rare diseases are generating robust and compelling clinical results. The rapid improvements in gene therapies over the past few years can be attributed to better scientific understanding of the critical quality attributes that contribute to a safe and efficacious product, as well as a better understanding of the manufacturing processes that are required to yield consistent products, which routinely meet the quality standards required for clinical studies. Of particular concern is the need for an effective, quality control (QC)-compatible, and versatile test method for the quantification of empty and full capsids in recombinant adeno-associated virus (rAAV) samples from multiple serotypes. In that regard, we describe the development of a QC-compatible anion-exchange chromatography method consisting of a modular discontinuous gradient to achieve full baseline peak separation and quantification of empty and full AAV capsids. Using an rAAV6 vector, our assay was shown to be precise, linear, robust, and accurate—correlating well with orthogonal methods such as analytical ultracentrifugation (AUC) and cryogenic transmission electron microscopy (Cryo-TEM). Additionally, we demonstrate the versatility of our approach by adapting the method to separate and quantify empty/full capsids in samples from several rAAV serotypes.