bluuebunny/crossref_metadata_2025 huggingface dataset:
Epigenetic mechanisms in paediatric brain tumours: regulators lose control
Authors: Badodi Sara , Marino Silvia
Published: March 2022

Epigenetic mechanisms are essential to regulate gene expression during normal development. However, they are often disrupted in pathological conditions including tumours, where they contribute to their formation and maintenance through altered gene expression. In recent years, next generation genomic techniques has allowed a remarkable advancement of our knowledge of the genetic and molecular landscape of paediatric brain tumours and have highlighted epigenetic deregulation as a common hallmark in their pathogenesis. This review describes the main epigenetic dysregulations found in paediatric brain tumours, including at DNA methylation and histone modifications level, in the activity of chromatin-modifying enzymes and in the expression of non-coding RNAs. How these altered processes influence tumour biology and how they can be leveraged to dissect the molecular heterogeneity of these tumours and contribute to their classification is also addressed. Finally, the availability and value of preclinical models as well as the current clinical trials exploring targeting key epigenetic mediators in paediatric brain tumours are discussed.
An increase in early cancer detection rates at a single cancer center: Experiences from Sun Yat-sen University Cancer Center
Authors: Xie Shang-Hang , Huang Ri-Qing , Liu Yi-Long , Cao Su-Mei , Qian Chao-Nan
Published: March 2022

Cancer has become a major fatal disease in China. The relatively lower early detection rates for multiple cancer types have been one of the main reasons for a relatively lower cancer curative rate in China compared with the developed countries. To investigate trends in the early cancer detection rate over the past 5 years in a major city of China, 45,260 patients with newly diagnosed cancers of the nasopharynx, lung, thyroid, colorectum, liver, breast, uteral cervix, stomach, esophagus, blood, and kidney from 2016 to 2020 at Sun Yat-sen University Cancer Center were evaluated. The early detection rate (stage I disease) for all cancer types in combination significantly increased from 14.4 to 23.07%. Among the studied cancer types, a significant increase in stage I cancers was proportionally seen in cancers of the lung, thyroid, colorectum, and uterine cervix. While for cancers of the liver and stomach, a significant proportional increment was only observed when combining stage I and stage II diseases. No significant alteration in early cancer detection of the nasopharynx, breast, esophagus, blood, or kidney was observed. Three limitations of this present study include relatively small cohorts of cancer patients, relatively short observation periods, and limited sample representativeness. Further efforts are anticipated to validate our findings with larger patient cohorts from different parts of China and enhance early cancer detection rates by promoting public awareness, applying better health care policies, and improving insurance coverage and medical resources.
Erfahrungen mit Blended Learning – ein neuartiges Konzept in die Tat umgesetzt
Authors: Schönefeld Eva , Glasbrenner Johannes , Stolberg-Stolberg Josef , Schliemann Benedikt , Raschke Michael , Roßlenbroich Steffen
Published: March 2022

Die weltweite Covid-19-Pandemie hatte in der letzten Zeit erhebliche Einschränkungen in allen Bereichen, in denen eine menschliche Interaktion über ein digitales Format hinaus notwendig
ist, wie Sozialleben, Kultur und insbesondere Ausbildung hervorgerufen. Insbesondere in der Ausbildung zu komplexen Berufen mit vielseitigen und besonders praktischen Ansprüchen, wie es die
Chirurgie ist, zeigte sich ein große Herausforderung. Sowohl etablierte als auch bewährte Konzepte der universitären Lehre und ärztlichen Weiterbildung galt es zu hinterfragen, zu
aktualisieren und mit modernen Medien neu zu gestalten. Die Entwicklung in den letzten 10 – 15 Jahren hatte bereits gezeigt, dass unterschiedliche edukative Prinzipien als auch didaktische
und pädagogische Perspektiven immer mehr zusammengefasst werden, um mit zunehmender Effektivität und ansteigender Qualität ein traditionelles Face-to-face Lernen mit digitalen Lehrkonzepten
zu kombinieren. Die weltweite Pandemie stellte in diesem Prozess einen erheblichen Akzelerator dar. Im Folgenden werden verschiedene Konzepte des Blended Learning dargestellt.
Kursevaluation in AO Trauma-Veranstaltungen – was haben wir gelernt?
Authors: Ghidinelli Monica
Published: March 2022

Um den Erfolg und die Effektivität von Fortbildungsveranstaltungen zu ermitteln und die Qualität der medizinischen Fortbildung zu verbessern, brauchen Kursanbieter, Dozierende und
Instruktoren von praktischen Übungen Zugang zu klar strukturierten und umfangreichen Evaluations- und Assessmentdaten. Die AO führte 2016 ein neues, schlankes und einheitliches Evaluations-
und Assessmentsystem ein, das AO Trauma Deutschland seit 2019 benutzt. Die erstellten Berichte haben den Dozierenden ermöglicht, die Fortbildungsveranstaltungen den Bedürfnissen der
Teilnehmer anzupassen. Das neue System hat es den verschiedenen Komitees auch ermöglicht, zukünftige Fortbildungsveranstaltungen zu planen und die Qualität der medizinischen Weiterbildung
stetig zu verbessern. Insgesamt waren die von AO Trauma Deutschland angebotenen Veranstaltungen erfolgreich und wurden den Bedürfnissen der Teilnehmer/-innen gerecht.
Minimal-invasive Therapie: Wie ist der Stand im Jahre 2021 – was kommt, was geht
Authors: Franz Julia , Gratzke Christian , Miernik Arkadiusz
Published: March 2022

Die Volkskrankheit „benignes Prostatasyndrom“ erfordert mit der Vielzahl an betroffenen Männern und einer variablen klinischen Präsentation individuelle Therapieoptionen, die auf die jeweiligen klinischen Charakteristika und Wünsche des Patienten zugeschnitten werden. Ist eine operative Therapie indiziert, steht ein großes Spektrum an invasiven Verfahren zur Verfügung. Als Goldstandard galten lange Zeit die transurethrale Resektion der Prostata und die offene Adenomenukleation, die jedoch mit erhöhter Morbidität und Einschränkungen der Sexualfunktion einhergehen. Daher wird zunehmend nach minimal-invasiven Therapieoptionen gefordert, die eine effektive und sichere Therapie im ambulanten Setting ermöglichen sollen. Über die letzten Jahre wurde eine Vielzahl an Technologien und Verfahren entwickelt und getestet, von denen nur wenige in der klinischen Praxis etabliert werden konnten, meist aufgrund unzureichender funktioneller Ergebnisse. Nicht mehr empfohlen werden daher die transurethrale Nadelablation, transurethrale Mikrowellentherapie, intraprostatische Botulinumtoxin-A- oder PRX302-Injektionen und prostatische Stents. Demgegenüber spricht die Europäische Gesellschaft für Urologie derzeit Empfehlungen für den UroLift, die Aquablation und die Prostataarterienembolisation aus, die langfristig signifikante Verbesserungen der funktionellen Parameter erreichen und dabei mit einem guten Sicherheitsprofil und erhaltener Sexualfunktion überzeugen. Vielversprechende Daten liegen auch für das temporär implantierte Nitinoldevice (iTIND), Rezūm, intraprostatische Injektionen von Fexapotid-Triflurtat und die transperineale Laserablation der Prostata vor, deren Effektivität und Sicherheit jedoch noch in weiteren Studien bestätigt werden müssen.
Risk Factors for Clinical Seizures in Neonates with
Hypoxic–ischemic Encephalopathy Treated with Therapeutic
Hypothermia
Authors: Bor Meltem , Ilhan Ozkan , Karaca Meryem , Calik Mustafa
Published: March 2022

Background This study aimed to assess the risk factors for clinical
seizures in newborns treated with whole body cooling (WBC) for hypoxic ischemic
encephalopathy (HIE).

Methods Infants with gestational age≥36 weeks and birth
weight≥2.000 g who were treated with WBC due to HIE were
retrospectively enrolled in this study. Patients were assigned to two groups:
infants without clinical seizures (Group 1) and infants with clinical seizures
(Group 2). The two groups were compared to determine the risk factors for the
occurrence of clinical seizures.

Results A total of 25 patients (Group 1=10 and Group 2=15)
were included in the study. Prothrombin time (PT) was determined as independent
risk factor for clinical seizures (p=0.046) and the odds ratio for the
effect of PT was found as 1.475 (%95 CI:1.006–2.299). PT (area
under the curve [AUC]=0.764; p=0.041), and increased cardiac
troponin-I (cTnI) (AUC=0.935; p=0.002) were found to be
significant risk factors for predicting the occurrence of clinical seizures. The
optimal PT cut-off value was 22.7 sec, with a sensitivity and
specificity of 45.4% and 90%, respectively; as well as positive
and negative predictive value of 83.3% and 60.0%, respectively.
The chest compression in the delivery room, severely abnormal amplitude
integrated electroencephalography and high encephalopathy score were also found
risk factors for occurrence of clinical seizures.

Conclusion Chest compression in the delivery room, high encephalopathy
score, prolonged PT, and increased cTnI are significant factors for clinical
seizures in newborns treated with WBC for HIE.
Phytotherapie bei Atemwegserkrankungen
Authors: Stange Rainer
Published: March 2022

Nicht zuletzt wegen der immer größer werdenden Probleme mit Resistenzen gegen Antibiotika stellen Phytotherapeutika eine vielversprechende Alternative bei der Therapie von Atemwegsinfektendar. Gerade bei Kindern wünschen sich viele Eltern eine naturheilkundliche Behandlung. Dabei können Therapeuten auf traditionell verwendete Pflanzen zurückgreifen, die nicht nur direkt antibakteriell, sondern auch immunmodulierend wirksam sind– ein entscheidender Vorteil gegenüber chemisch definierten Substanzen.
Behandlung von Schleimerkrankungen in den oberen Atemwegen aus Sicht der Traditionellen Chinesischen Medizin
Authors: Klützke Nina T.
Published: March 2022

In der Hals-Nasen-Ohren-Heilkunde sind Schleimerkrankungen häufig Ausdruck einer schlechten Stoffwechselsituation im Körper. Im Sinne der Traditionellen Chinesischen Medizin (TCM) sind sie Zeichen einer Milz-Qi-Schwäche. Zur Behandlung kommen in der TCM sowohl Arzneimittel als auch Akupunktur zum Einsatz. Wichtig ist auch, dass die Patienten ihre Ernährungs- und Bewegungsgewohnheiten sowie ihren Lebensstil umstellen.
Fallbeispiel: Langzeitverlauf von Bronchiektasien und rezidivierenden Pneumonien
Authors: Koch Barbara , Stange Rainer
Published: March 2022

Diese Kasuistik demonstriert das Fallbeispiel einer Patientin, die über mehrere Jahre hinweg unter wiederkehrenden Bronchitiden und Pneumonien litt. Neben einer Antibiotika-Behandlung in Akutphasen wandte die Patientin durchgehend auch naturheilkundliche Therapien sowie andere Maßnahmen an. Dazu gehörten pflanzliche Arzneimittel zur Schleimlösung, Immunstimulanzien,Kneipp’sche Techniken, Atemgymnastik, Inhalation, körperliche Aktivität sowie eine Ernährungsumstellung. Im CT konnte nach diesen Maßnahmen eine Besserung des Befunds festgestellt werden.
Cyclization of o-Alkynylisocyanobenzenes with 1,3-Dicarbonyl Compounds
Authors: Kuhakarn Chutima , La-ongthong Kannika , Sawekteeratana Natthapat , Klaysuk Jasarin , Soorukram Darunee , Leowanawat Pawaret , Reutrakul Vichai , Krobthong Sucheewin , Wongtrakoongate Patompon
Published: March 2022

A facile and convenient reaction of o-alkynylisocyanobenzenes with various active-methylene compounds, including 1,3-diesters, 1,3-diketones, β-keto esters, and β-keto amides, under Brønsted basic conditions, has been developed. Diethyl malonate reacted smoothly with a collection of o-alkynylisocyanobenzenes to provide the corresponding 2-quinolin-2-yl malonates in excellent yields. Acetylacetone gave a mixture of quinolin-4-yl and quinolin-2-yl derivatives. Acetoacetate esters and acetoacetyl amide derivative initially gave 2-quinolin-2-yl adducts that underwent partial deacetylation under the reaction conditions.
Systemic Antiangiogenic Therapies for Bleeding in Hereditary Hemorrhagic Telangiectasia: A Practical, Evidence-Based Guide for Clinicians
Authors: Al-Samkari Hanny
Published: March 2022

Management of bleeding in hereditary hemorrhagic telangiectasia (HHT), the second most common hereditary bleeding disorder in the world, is currently undergoing a paradigm shift. Disease-modifying antiangiogenic therapies capable of achieving durable hemostasis via inducing telangiectasia regression have emerged as a highly effective and safe modality to treat epistaxis and gastrointestinal bleeding in HHT. While evidence to date is incomplete and additional studies are ongoing, patients presently in need are being treated with antiangiogenic agents off-label. Intravenous bevacizumab, oral pazopanib, and oral thalidomide are the three targeted primary angiogenesis inhibitors, with multiple studies describing both reassuring safety and impressive effectiveness in the treatment of moderate-to-severe HHT-associated bleeding. However, at present there is a paucity of guidance in the literature, including the published HHT guidelines, addressing the practical aspects of antiangiogenic therapy for HHT in clinical practice. This review article and practical evidence-based guide aims to fill this unaddressed need, synthesizing published data on the use of antiangiogenic agents in HHT, relevant data for their use outside of HHT, and expert guidance where evidence is lacking. After a brief review of principles of bleeding therapy in HHT, guidance on hematologic support with iron and blood products, and alternatives to antiangiogenic therapy, this article examines each of the aforementioned antiangiogenic agents in detail, including patient selection, initiation, monitoring, toxicity management, and discontinuation. With proper, educated use of antiangiogenic therapies in HHT, patients with even the most severe bleeding manifestations can achieve durable hemostasis with minimal side-effects, dramatically improving health-related quality of life and potentially altering the disease course.
Understanding the characteristics of non-equilibrium alternating current gliding arc discharge in a variety of gas mixtures (air, N2, Ar, Ar/O2, and Ar/CH4) at elevated pressures (1–5 atm)
Authors: Kong Chengdong , Gao Jinlong , Ehn Andreas , Aldén Marcus , Li Zhongshan
Published: March 2022

This work aims at clarifying the fundamental mechanisms of non-equilibrium alternating current gliding arc discharge (GAD) by investigating effects of gas compositions and pressures on the GAD characteristics with electrical and optical methods. Interestingly, the glow-to-spark transition was found by adding O2 or CH4 into the argon or modulating the power supply. This transition occurs attributed to the fact that the discharge mode is largely affected by the effective electron decay time (τ) as well as the feedback response of the power supply to the free electron density in the GAD. Short τ or low free electron density tends to result in the spark-type discharge. It further implies that the power supply characteristics is crucial for discharge mode control. The pressure effects on the GAD characteristics were found to vary with gas composition when the same alternating current power supply was used. In N2 or air, the emission intensity from the plasma column increases with pressure while the mean electric field strength (E) along the plasma column decreases with pressure. Differently, in Ar, the emission intensity and E do not change much with pressure. It can be explained by the different energy partition and transfer pathways between monatomic and molecular species. The molecular gases have vibrational excitation pathways to facilitate the electronic excitation and ionization that is different from the monatomic gas.
Modeling the filtration efficiency of a woven fabric: The role of multiple lengthscales
Authors: Rios de Anda Ioatzin , Wilkins Jake W. , Robinson Joshua F. , Royall C. Patrick , Sear Richard P.
Published: March 2022

During the COVID-19 pandemic, many millions have worn masks made of woven fabric to reduce the risk of transmission of COVID-19. Masks are essentially air filters worn on the face that should filter out as many of the dangerous particles as possible. Here, the dangerous particles are the droplets containing the virus that are exhaled by an infected person. Woven fabric is unlike the material used in standard air filters. Woven fabric consists of fibers twisted together into yarns that are then woven into fabric. There are, therefore, two lengthscales: the diameters of (i) the fiber and (ii) the yarn. Standard air filters have only (i). To understand how woven fabrics filter, we have used confocal microscopy to take three-dimensional images of woven fabric. We then used the image to perform lattice Boltzmann simulations of the air flow through fabric. With this flow field, we calculated the filtration efficiency for particles a micrometer and larger in diameter. In agreement with experimental measurements by others, we found that for particles in this size range, the filtration efficiency is low. For particles with a diameter of 1.5 μm, our estimated efficiency is in the range 2.5%–10%. The low efficiency is due to most of the air flow being channeled through relatively large (tens of micrometers across) inter-yarn pores. So, we conclude that due to the hierarchical structure of woven fabrics, they are expected to filter poorly.
Persistent photoconductivity in barium titanate
Authors: Pansegrau Christopher , McCluskey Matthew D.
Published: March 2022

Annealed bulk crystals of barium titanate (BaTiO3) exhibit persistent photoconductivity (PPC) at room temperature. Samples were annealed in a flowing gas of humid argon and hydrogen, with a higher flow rate corresponding to larger PPC. When exposed to sub-bandgap light, a broad infrared (IR) absorption peak appears at 5000 cm−1 (2 μm), attributed to polaronic or free-carrier absorption from electrons in the conduction band. Along with the increased IR absorption, electrical resistance is reduced by a factor of approximately two. The threshold photon energy for PPC is 2.9 eV, similar to the case of SrTiO3. This similarity suggests that the mechanisms are similar: an electron in substitutional hydrogen (HO) is photoexcited into the conduction band, causing the proton to leave the oxygen vacancy and attach to a host oxygen atom. The barrier to recover to the ground state is large such that PPC persists at room temperature.
Condensation of 2D exciton-polaritons in an open-access microcavity
Authors: Li Feng , Li Yiming , Giriunas L. , Sich M. , Solnyshkov D. D. , Malpuech G. , Trichet A. A. P. , Smith J. M. , Clarke E. , Skolnick M. S. , Krizhanovskii D. N.
Published: March 2022

We establish a tunable open-access microcavity consisting of two planar distributed Bragg reflectors (DBRs) individually controlled by nanopositioners. By varying the cavity length, such configuration enables variation of the light–matter coupling strength by a factor of 2, while keeping in microresonators the same active region and cavity mirrors. Polariton condensation was demonstrated over a large range of Rabi splittings and the corresponding threshold diagram was derived as a function of cavity-exciton detuning, which fits well with theoretical simulations. The results show that for various light-matter coupling strengths, optimal detunings featured by the lowest condensation threshold always occur at a fixed depth of energy trap between the exciton reservoir and the polariton ground state, which enables the most efficient exciton–exciton scattering into the condensate state in the driven-dissipative polaritonic system.
Air-core vortex formation in a draining reservoir using smoothed-particle hydrodynamics (SPH)
Authors: Azarpira M. , Zarrati A. R. , Farokhzad P. , Shakibaeinia A.
Published: March 2022

Vortex formation under unsteady flow conditions in a draining reservoir is studied. Considering the capabilities of mesh-free Lagrangian numerical methods in the simulation of highly deformed free surfaces, the smoothed-particle hydrodynamics approach is employed. The results of this numerical model are validated with the experimental data of the current study, including the depth over the intake at which vortex forms (critical submergence) and the velocity field. Experiments were also conducted in a rotating cylinder while water was draining from an outlet at its bottom center. The particle image velocimetry technique was used for measuring the velocity field in planes perpendicular to the vortex axis. The numerical results including the velocity distribution and water level variations as well as the depth at which an air-core forms were in acceptable agreement with the experimental data. In addition, vortex formation and the corresponding velocity and pressure distribution as well as the streamlines are analyzed based on the numerical results. The results indicate that as the flow depth decreases, high values of vorticity and low pressures are generated at the vicinity of the outlet, and over time, the generated vorticity develops in depth toward the free surface, and an air-core vortex forms.
High-precision background correction and artifact suppression for ultrafast spectroscopy by quasi-simultaneous measurements in a split-sample cell
Authors: Deniz E. , Löffler J. G. , Kondratiev A. , Thun A. R. , Shen Y. , Wille G. , Bredenbeck J.
Published: March 2022

Alternating acquisition of background and sample spectra is often employed in conventional Fourier-transform infrared spectroscopy or ultraviolet–visible spectroscopy for accurate background subtraction. For example, for solvent background correction, typically a spectrum of a cuvette with solvent is measured and subtracted from a spectrum of a cuvette with solvent and solute. Ultrafast spectroscopies, though, come with many peculiarities that make the collection of well-matched, subtractable background and sample spectra challenging. Here, we present a demountable split-sample cell in combination with a modified Lissajous scanner to overcome these challenges. It allows for quasi-simultaneous measurements of background and sample spectra, mitigating the effects of drifts of the setup and maintaining the beam and sample geometry when swapping between background and sample measurements. The cell is moving between subsequent laser shots to refresh the excited sample volume. With less than 45 μl of solution for 150 μm optical thickness, sample usage is economical. Cell assembly is a key step and covered in an illustrated protocol.
Effect of electron density gradient on power absorption during gigahertz electromagnetic wave propagating in cold plasma
Authors: Li Jiang-Jiang , Xi Yan-Bin , Gao Na , Wang Zhi-Qiang , Wang Qian , Liu Yue
Published: March 2022

Considering the effect of electron density gradient, an analytical, parameter adjustable density distribution function is presented, and a multislab plasma model is used to investigate power absorption of gigahertz electromagnetic waves between 0.20 and 30 GHz in a partially ionized cold plasma layer. The effects of plasma parameters on the absorbed power during electromagnetic wave propagation are investigated and compared with corresponding uniform cases. An optimized asymmetric electron density gradient profile is designed by calculating the corresponding absorption spectrum with selected parameters to enhance the absorption rate near original peak frequencies. The possibility of theoretically designing electron density gradient profiles is important to understand how to enhance the plasma cloaking in some specific electromagnetic wave frequency bands.
Temperature and ambient atmosphere dependent electrical characterization of sputtered IrO2/TiO2/IrO2 capacitors
Authors: Maier F. J. , Schneider M. , Artemenko A. , Kromka A. , Stöger-Pollach M. , Schmid U.
Published: March 2022

Titanium dioxide (TiO2) is a high-performance material for emerging device applications, such as in resistive switching memories, in high-k capacitors, or, due to its flexoelectricity, in micro/nano-electro-mechanical systems. Enhanced electrical properties of TiO2 are ensured, especially by a careful selection of the bottom electrode material. Iridium dioxide (IrO2) is an excellent choice, as it favors the high-k rutile phase growth of TiO2. In this study, we introduce the fabrication of IrO2/TiO2/IrO2 capacitors and thoroughly characterize their electrical behavior. These capacitors show a dielectric constant for low temperature sputtered TiO2 of ∼70. From leakage current measurements, a coupled capacitive–memristive behavior is determined, which is assumed due to the presence of a reduced TiO2−x layer at the IrO2/TiO2 interface observed from transmission electron microscopy analyses. The memristive effect most probably originates from trapping and detrapping of electric charges in oxygen vacancy defects, which themselves can be generated and annihilated through an applied electric field, subsequently changing the resistance of the capacitor. The electric degradation type is identified as a filament-forming mechanism. Additionally, the temperature dependence of the leakage current is measured, demonstrating that the temperature behavior is strongly influenced by the ambient atmosphere. The latter dependency leads to the hypothesis that the oxygen evolution reaction of water incorporated in the IrO2/TiO2 interface passivates vacancies, thus significantly impacting the vacancy density in TiO2 and, as a further consequence, the electrical performance.
Theoretical analysis of time-dependent jetting on the surface of a thin moving liquid layer
Authors: Shishmarev K. A. , Khabakhpasheva T. I. , Korobkin A. A.
Published: March 2022

Unsteady two-dimensional problem of a thin liquid layer with prescribed time-dependent influx into the layer, position of the influx section, and the thickness of the liquid at this section is studied by methods of asymptotic analysis. The ratio of the rate of the liquid thickness variation at the influx section to the influx velocity plays a role of a small parameter of the problem. The influx parameters are such that the flow in the thin layer is inertia dominated, with gravity, surface tension, and liquid viscosity being approximately negligible. Such flows were studied with respect to several applications, some of which are listed in the Introduction. One of the applications concerns with splashing during droplet impact onto a rigid substrate and related kinematic discontinuity propagating along the spray sheet, which is produced by the spreading droplet. This type of splashing was studied by Yarin and Weiss [“Impact of drops on solid surfaces: Self-similar capillary waves, and splashing as a new type of kinematic discontinuity,” J. Fluid Mech. 283, 141–173 (1995)] within a quasi-one-dimensional approach averaging the flow velocity over the layer thickness. We also start with the one-dimensional thin-layer approximation assuming the influx flow is accelerated. Such influx conditions lead to unbounded growth of the thickness of the liquid layer at a certain location and at a certain time instant within the one-dimensional approach. The present study recovers for the first time the structure of the flow close to this singularity using methods of asymptotic analysis. To this aim, the second-order outer solution, which is valid outside the region of the unbounded flow, is derived. The second-order outer solution is used to find proper stretched inner variables and the equations governing the inner flow at the leading order. It is shown that the inner free-surface flow in the stretched variables is two-dimensional, potential, non-linear, and independent of any parameters of the original problem.
Lattice Boltzmann simulation of binary three-dimensional droplet coalescence in a confined shear flow
Authors: Huang Bingquan , Liang Hong , Xu Jiangrong
Published: March 2022

Small-scale microscopic phenomena determine the behavior of large-scale droplets, which brings great challenges to accurately simulate the droplet coalescence process. In this paper, the mesoscopic lattice Boltzmann method based on the phase field theory is used to simulate the collision and coalescence of binary three-dimensional droplets in a confined shear flow. The numerical prediction of droplet coalescence behavior was first compared with the experimental result, and good agreement was reported. Then, we investigated the influences of a comprehensive range of capillary numbers (0.01≤Ca≤0.5) and Reynolds numbers (0.01≤Re≤10) on the shearing dynamics of binary droplets and also provided a quantitative description of droplet behavior in terms of the droplet deformation parameter and relative trajectory. A shearing regime diagram is further constructed based on the coupling effect of Ca and Re, which reveals three distinct types of droplet behaviors, including coalescence, breakup after the coalescence, and non-coalescence. Concretely, three different patterns of droplets can be completely captured with the variation of Ca at low Re; only two types of coalescence and non-coalescence can be observed for a medium Re, and two droplets just slide over each other without the occurrence of the coalescence when Re is sufficiently large. Also, we identified two critical capillary numbers in the lower Re region and one critical capillary number in the middle Re region, respectively, characterizing flow type transitions from the coalescence to breakup, from the breakup to the non-coalescence, and from the coalescence to the non-coalescence. It is found that all the capillary numbers decrease with Re.
Flow enhancement of tomographic particle image velocimetry measurements using sequential data assimilation
Authors: He Chuangxin , Wang Peng , Liu Yingzheng , Gan Lian
Published: March 2022

Sequential data assimilation (DA) was performed on three-dimensional flow fields of a circular jet measured by tomography particle image velocimetry (tomo-PIV). The work focused on an in-depth analysis of the flow enhancement and the pressure determination from volumetric flow measurement data. The jet was issued from a circular nozzle with an inner diameter of D= 20 mm. A split-screen configuration including two high-speed cameras was used to capture the particle images from four different views for a tomography reconstruction of the voxels in the tomo-PIV measurement. Planar PIV was also performed to obtain the benchmark two-dimensional velocity fields for validation. The adjoint-based sequential DA scheme was used with the measurement uncertainty implanted using a threshold function to recover the flow fields with high fidelity and fewer measurement errors. The pressure was determined by either the direct mode, with implementation directly in the DA solver, or by the separate mode, which included solving the Poisson equation on the DA-recovered flow fields. Sequential DA recovered high signal-to-noise flow fields that had piecewise-smooth temporal variations due to the intermittent constraints of the observations, while only the temporal sequence of the fields at the observational instances was selected as the DA output. Errors were significantly reduced, and DA improved the divergence condition of the three-dimensional flow fields. DA also enhanced the dynamical features of the vortical structures, and the pressure determined by both modes successfully captured the downstream convection signatures of the vortex rings.
A parametric and feasibility study for data sampling of the dynamic mode decomposition: Spectral insights and further explorations
Authors: Li Cruz Y. , Chen Zengshun , Tse Tim K. T. , Weerasuriya Asiri Umenga , Zhang Xuelin , Fu Yunfei , Lin Xisheng
Published: March 2022

The present work extends the parametric investigation on the sampling nuances of dynamic mode decomposition (DMD) under Koopman analysis. Through turbulent wakes, the study corroborated the generality of universal convergence states for all DMD implementations. It discovered implications of sampling range and resolution—determinants of spectral discretization by discrete bins and the highest resolved frequency range, respectively. The work reaffirmed the necessity of the convergence state for sampling independence, too. Results also suggested that the observables derived from the same flow may contain dynamically distinct information, thus altering the DMD output. Surface pressure and vortex fields are optimal for characterizing the structure and the flow field, respectively. Pressure, velocity magnitude, and turbulence kinetic energy also suffice for general applications, but Reynolds stresses and velocity components shall be avoided. Mean-subtraction is recommended for the best approximations of Koopman eigen tuples. Furthermore, the parametric investigation on truncation discovered some low-energy states that dictate a system's temporal integrity. The best practice for order reduction is to avoid truncation and employ dominant mode selection on a full-state subspace, though large-degree truncation supports fair data reconstruction with low computational cost. Finally, this work demonstrated synthetic noise resulting from pre-decomposition interpolation. In unavoidable interpolations to increase the spatial dimension n, high-order schemes are recommended for better retention of original dynamics. Finally, the observations herein, derived from inhomogeneous anisotropic turbulence, offer constructive references for DMD on fluid systems, if not also for others beyond fluid mechanics.
Analytical prediction of electrowetting-induced jumping motion for droplets on textured hydrophobic substrates: Effects of the wetting states
Authors: Zhang Kaixuan , Zhao Jiayi , Liu Yang , Chen Shuo
Published: March 2022

In electrowetting, an applied electric voltage can induce spreading, sliding, or even jumping of an individual droplet by changing the intrinsic balance of the three-phase interfacial tensions. This technique has been widely used for manipulating droplets in microfluidics and by lab-on-a-chip devices in recent decades. In the present paper, we present an analytical prediction of the jumping velocity for droplets undergoing electrowetting on textured hydrophobic surfaces with different wetting states. In particular, we consider wetting a liquid droplet on a textured hydrophobic substrate with a voltage applied between the droplet and the substrate. Once the voltage is turned off, the energy stored in the droplet during electrowetting is released and could even result in the detachment of the droplet. The effects of the initial and electrowetting states, i.e., the Cassie–Baxter state and the Wenzel state, on the jumping velocity of droplets are systematically discussed. Based on energy conservation, the energy conversion between the surface energy, the elastic energy of the contact line, and the kinetic energy of droplets due to internal viscous dissipation in different wetting states is analyzed. Closed-form formulas for the jumping velocity of different droplet wetting states are systematically derived. Finally, a unified form for predicting the electrowetting-induced jumping velocity of droplets on both flat and textured substrates with different wetting states is obtained. It can describe the jumping motion under various wetting conditions, which is validated by some experimental results. This work provides theoretical insights into the accurate control of the electrowetting-induced jumping motion of droplets on textured hydrophobic surfaces.
Analysis of beam currents under an oscillating cone-jet mode for developing high-precision electrospray thrusters
Authors: Zhang Kai , Kuang Shuangyang , Suo Xiaochen , Huang Xiaobo , Li Zixue , Wang Dian , Jia Hongyu , Tu Liangcheng , Song Peiyi
Published: March 2022

As an application of electrospray, electrospray thrusters are preferred to work in a steady electrohydrodynamic mode to output high-precision and adjustable thrust through controlling voltages and flow rates. However, voltages and flow rates can only be modified in a small range to avoid mode transiting, thereby limiting the thrust range. To increase the thrust, adding the number of emitters or more grids for beam acceleration is considered, but it inevitably increases mechanical complexities and risks of component failure. In this paper, electrosprays are investigated by analyzing the beam current over the time and frequency domains. Results suggest that the steady cone-jet transfers into an oscillating cone-jet with a frequency of several kHz as the flow rate increases. In the oscillating cone-jet mode, beam currents and flow rates still follow the power-law relation, which is derived for the steady cone-jet. The finding suggests that setting a desired thrust over the oscillating cone-jet mode is feasible, whose maximum thrust allowed is 2.3 times the one in the steady cone-jet mode. The calculated thrust noises of the oscillating cone-jet mode are lower than 0.1 μN/Hz0.5 in the millihertz band, which meets the requirement of most drag-free satellites. The oscillation frequency is also adjustable by changing voltages or flow rates, offering another control parameter for electrospray devices. Compared to other instable modes, the oscillating cone-jet mode demonstrates superior low-noise output and controllability, thereby making it another suitable operational mode for high-precision electrospray thrusters in addition to the steady cone-jet mode.
Linear temporal stability analysis on cross sheared flow: The stabilization effects via cross shear
Authors: Xiao Yuan , Lin Wenxian
Published: March 2022

The stability features of the inviscid, homogenous, and free cross sheared flow, with base flow velocities U=tanh(z) in the primary direction, which is unstable, and V=ξz3 in the orthogonal direction, which is stable, are thoroughly examined with linear temporal stability analysis, where z is the transverse coordinate perpendicular to the flow and ξ is the cross shear ratio which is the ratio of the characteristic magnitudes of V to U. The map of the unstable regions directly related to χ=ξ(β/α) is obtained, where (β/α) is the ratio between the orthogonal and primary wavenumbers. Further examination of the eigenfunctions shows that the eigenfunction structures divide into the orthogonal wavenumber (OW) mode where (β/α) dominates and the cross shear (CS) mode where ξ dominates. The cross shear is found necessary for stabilization in spite of different fashions for the OW and CS modes. The transition from the OW mode to the CS mode shows that the developments of the two modes inherently compete with each other, so that when ψ=(β/α)/ξ decreases the enhanced cross shear needs to deteriorate the OW mode before it helps the growth of the CS mode. Based on the magnitudes of the associated eigenfunctions in the enstrophy budget, the map of the OW, CS, and hybrid modes, which includes the mixed features of both the OW and CS modes, is produced and discussed.
H2O inside the fullerene C60: Inelastic neutron scattering spectrum from rigorous quantum calculations
Authors: Xu Minzhong , Felker Peter M. , Bačić Zlatko
Published: March 2022

We present a methodology that, for the first time, allows rigorous quantum calculation of the inelastic neutron scattering (INS) spectra of a triatomic molecule in a nanoscale cavity, in this case, H2O inside the fullerene C60. Both moieties are taken to be rigid. Our treatment incorporates the quantum six-dimensional translation–rotation (TR) wave functions of the encapsulated H2O, which serve as the spatial parts of the initial and final states of the INS transitions. As a result, the simulated INS spectra reflect the coupled TR dynamics of the nanoconfined guest molecule. They also exhibit the features arising from symmetry breaking observed for solid H2O@C60 at low temperatures. Utilizing this methodology, we compute the INS spectra of H2O@C60 for two incident neutron wavelengths and compare them with the corresponding experimental spectra. Good overall agreement is found, and the calculated spectra provide valuable additional insights.
The US is in dire need of STEM teachers
Authors: Feder Toni
Published: March 2022

Faculty attitudes, public perceptions, tuition, and state requirements are barriers to science majors entering the teaching profession.
Philip Anderson: Virtuoso of condensed matter
Authors: Zangwill Andrew
Published: March 2022

The theorist’s work on disordered and magnetic solids earned him a Nobel Prize, but it was his profound influence on the condensed-matter community—and well beyond—that set him apart.
Epitope convergence of broadly HIV-1 neutralizing IgA and IgG antibody lineages in a viremic controller
Authors: Lorin Valérie , Fernández Ignacio , Masse-Ranson Guillemette , Bouvin-Pley Mélanie , Molinos-Albert Luis M. , Planchais Cyril , Hieu Thierry , Péhau-Arnaudet Gérard , Hrebík Dominik , Girelli-Zubani Giulia , Fiquet Oriane , Guivel-Benhassine Florence , Sanders Rogier W. , Walker Bruce D. , Schwartz Olivier , Scheid Johannes F. , Dimitrov Jordan D. , Plevka Pavel , Braibant Martine , Seaman Michael S. , Bontems François , Di Santo James P. , Rey Félix A. , Mouquet Hugo
Published: March 2022

Decrypting the B cell ontogeny of HIV-1 broadly neutralizing antibodies (bNAbs) is paramount for vaccine design. Here, we characterized IgA and IgG bNAbs of three distinct B cell lineages in a viremic controller, two of which comprised only IgG+ or IgA+ blood memory B cells; the third combined both IgG and IgA clonal variants. 7-269 bNAb in the IgA-only lineage displayed the highest neutralizing capacity despite limited somatic mutation, and delayed viral rebound in humanized mice. bNAbs in all three lineages targeted the N332 glycan supersite. The 2.8-Å resolution cryo-EM structure of 7-269-BG505 SOSIP.664 complex showed a similar pose as 2G12, on an epitope mainly composed of sugar residues comprising the N332 and N295 glycans. Binding and cryo-EM structural analyses showed that antibodies from the two other lineages interact mostly with glycans N332 and N386. Hence, multiple B cell lineages of IgG and IgA bNAbs focused on a unique HIV-1 site of vulnerability can codevelop in HIV-1 viremic controllers.
Quantitative dynamics of irreversible enzyme reaction–diffusion systems
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Authors: Braukhoff Marcel , Einav Amit , Tang Bao Quoc
Published: March 2022

In this work we investigate the convergence to equilibrium for mass action reaction–diffusion systems which model irreversible enzyme reactions. Using the standard entropy method in this situation is not feasible as the irreversibility of the system implies that the concentrations of the substrate and the complex decay to zero. The key idea we utilise in this work to circumvent this issue is to introduce a family of cut-off partial entropy-like functionals which, when combined with the dissipation of a mass like term of the substrate and the complex, yield an explicit exponential convergence to equilibrium. This method is also applicable in the case where the enzyme and complex molecules do not diffuse, corresponding to chemically relevant situation where these molecules are large in size.
Center manifolds without a phase space for quasilinear problems in elasticity, biology, and hydrodynamics
Authors: Chen Robin Ming , Walsh Samuel , Wheeler Miles H
Published: March 2022

In this paper, we present a center manifold reduction theorem for quasilinear elliptic equations posed on infinite cylinders that is done without a phase space in the sense that we avoid explicitly reformulating the PDE as an evolution problem. Under suitable hypotheses, the resulting center manifold is finite dimensional and captures all sufficiently small bounded solutions. Compared with classical methods, the reduced ODE on the manifold is more directly related to the original physical problem and also easier to compute. The analysis is conducted directly in Hölder spaces, which is often desirable for elliptic equations. We then use this machinery to construct small bounded solutions to a variety of systems. These include heteroclinic and homoclinic solutions of the anti-plane shear problem from nonlinear elasticity; exact slow moving invasion fronts in a two-dimensional Fisher–KPP equation; and hydrodynamic bores with vorticity in a channel. The last example is particularly interesting in that we find solutions with critical layers and distinctive ‘half cat’s eye’ streamline patterns.
Impact of BNT162b2 Vaccination and Isolation on SARS-CoV-2 Transmission in Israeli Households: An Observational Study
Authors: Layan Maylis , Gilboa Mayan , Gonen Tal , Goldenfeld Miki , Meltzer Lilac , Andronico Alessio , Hozé Nathanaël , Cauchemez Simon , Regev-Yochay Gili
Published: March 2022

Several studies have characterized the effectiveness of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. However, estimates of their impact on transmissibility remain limited. Here, we evaluated the impact of isolation and vaccination (7 days after the second dose) on SARS-CoV-2 transmission within Israeli households. From December 2020 to April 2021, confirmed cases were identified among health-care workers of the Sheba Medical Centre and their family members. Recruited households were followed up with repeated PCR for at least 10 days after case confirmation. Data were analyzed using a data augmentation Bayesian framework. A total of 210 households with 215 index cases were enrolled; 269 out of 667 (40%) susceptible household contacts developed a SARS-CoV-2 infection. Of those, 170 (63%) developed symptoms. Compared with unvaccinated and unisolated adult/teenager (aged >12 years) contacts, vaccination reduced the risk of infection among unisolated adult/teenager contacts (relative risk (RR) = 0.21, 95% credible interval (CrI): 0.08, 0.44), and isolation reduced the risk of infection among unvaccinated adult/teenager (RR = 0.12, 95% CrI: 0.06, 0.21) and child contacts (RR = 0.17, 95% CrI: 0.08, 0.32). Infectivity was reduced in vaccinated cases (RR = 0.25, 95% CrI: 0.06, 0.77). Within households, vaccination reduces both the risk of infection and of transmission if infected. When contacts were unvaccinated, isolation also led to important reductions in the risk of transmission.
Topological ranks reveal functional knowledge encoded in biological networks: a comparative analysis
Authors: Bonomo Mariella , Giancarlo Raffaele , Greco Daniele , Rombo Simona E
Published: March 2022

Motivation

Biological networks topology yields important insights into biological function, occurrence of diseases and drug design. In the last few years, different types of topological measures have been introduced and applied to infer the biological relevance of network components/interactions, according to their position within the network structure. Although comparisons of such measures have been previously proposed, to what extent the topology per se may lead to the extraction of novel biological knowledge has never been critically examined nor formalized in the literature.

Results

We present a comparative analysis of nine outstanding topological measures, based on compact views obtained from the rank they induce on a given input biological network. The goal is to understand their ability in correctly positioning nodes/edges in the rank, according to the functional knowledge implicitly encoded in biological networks. To this aim, both internal and external (gold standard) validation criteria are taken into account, and six networks involving three different organisms (yeast, worm and human) are included in the comparison. The results show that a distinct handful of best-performing measures can be identified for each of the considered organisms, independently from the reference gold standard.

Availability

Input files and code for the computation of the considered topological measures and K-haus distance are available at https://gitlab.com/MaryBonomo/ranking.

Contact

simona.rombo@unipa.it

Supplementary information

Supplementary data are available at Briefings in Bioinformatics online.