bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence and clinical relevance of udder thigh dermatitis in dairy cows
Authors: Avenarius Andreas , Wehrend Axel , Sickinger Marlene
Published: September 2022

Objective Udder thigh dermatitis (UTD) is especially common in heifers. Skin alterations and necrosis of muscle tissue characterise this condition and, although the disease is well understood, systematic analysis concerning prevalence, risk factors and consequences of UTD is lacking. The aim of this study, therefore were such systematic clinical examinations.

Material and methods Statistical analyses of data were performed to objectively evaluate the supposed higher risk of heifers developing UTD. The study included a total of 317 animals that were examined and classified as UTD positive or negative on the day of calving. The size of skin alterations and the severity of tissue damage were assessed on days 7, 14 and 21 p. p.

Results The overall prevalence resulted in 18 % UTD with a higher risk in heifers (36.8 %) than in cows (4.3 %; P < 0.0001). A significant link was found between the size of tissue lesions and severity of UTD (day 7: P = 0.007; day 14: P = 0.002; day 21: P = 0.011). Peripartal udder oedemas were strongly associated with UTD (P < 0.05). The milk yield and the concentration of milk protein was found to have decreased.

Conclusion UTD appears to be a multi-factorial disease that is supposed to be painful due to the obvious avoidant behaviour in affected animals. In respect to the reduction in daily milk yield and an enhancement of pain related stress, neither the economic impact of UTD, nor the adverse effects on animal welfare should be underestimated.

Clinical relevance Heifers with udder oedema are advised to be examined for the presence of UTD in order to start an early treatment and diminish disease related negative impacts.
Pigeon Rotavirus A as the cause of systemic infection in juvenile pigeons (young pigeon disease)
Authors: Meßmer Christian , Rubbenstroth Dennis , Mohr Lydia , Peus Elisabeth , Schreiber Tim , Rautenschlein Silke
Published: September 2022

Recent investigations suggested pigeon associated Rotavirus Typ A genotype G18P[17] (RVA) as a causative agent of the classical ‘young pigeon disease’ (YPD). YPD was first described in the late 1980 s as an acute, mainly seasonally recurring disorder of mostly juvenile domestic pigeons (Columba livia) with clinical signs such as anorexia, dairrhea, vomiting, congested crops, weight loss and occasionally mortality. Various studies in the past indicated a multifactorial nature of YPD. Several pathogens, such as pigeon circovirus 1, avian adenoviruses and Escherichia coli were also suggested, but none of these could reproduce the disease experimentally. However, the impact of other pathogens on the clinical development of YPD cannot be excluded and requires further investigation. This present review summarizes available information on RVA-induced disease in pigeons, its association with YPD, the transmission, and diagnosis of the infection, and on prophylactic strategies to prevent RVA outbreaks.
Placenta Accreta Spectrum Prenatal Diagnosis Performance: Are Ultrasound False-positive Results Acceptable in Limited-resources Settings?
Authors: Nieto-Calvache Albaro José , Benavides-Calvache Juan Pablo , Hidalgo Alejandra , Padilla Natalia , López-Tenorio Jaime , Victoria Alejandro , Rengifo Martin , Mejía Mauricio , Vergara-Galliadi Lina María , Sinisterra-Díaz Stiven Ernesto , Maya Juliana , Zambrano María Andrea , Burgos-Luna Juan Manuel
Published: September 2022

Objective The immediate referral of patients with risk factors for placenta accreta spectrum (PAS) to specialized centers is recommended, thus favoring an early diagnosis and an interdisciplinary management. However, diagnostic errors are frequent, even in referral centers (RCs). We sought to evaluate the performance of the prenatal diagnosis for PAS in a Latin American hospital.

Methods A retrospective descriptive study including patients referred due to the suspicion of PAS was conducted. Data from the prenatal imaging studies were compared with the final diagnoses (intraoperative and/or histological).

Results A total of 162 patients were included in the present study. The median gestational age at the time of the first PAS suspicious ultrasound was 29 weeks, but patients arrived at the PAS RC at 34 weeks. The frequency of false-positive results at referring hospitals was 68.5%. Sixty-nine patients underwent surgery based on the suspicion of PAS at 35 weeks, and there was a 28.9% false-positive rate at the RC. In 93 patients, the diagnosis of PAS was ruled out at the RC, with a 2.1% false-negative frequency.

Conclusion The prenatal diagnosis of PAS is better at the RC. However, even in these centers, false-positive results are common; therefore, the intraoperative confirmation of the diagnosis of PAS is essential.
Predicting supersonic jet screech
Authors: Piccone Ashley
Published: September 2022

Underexpanded jets emit a powerful acoustic tone during the starting process, which can be analyzed and characterized with large-eddy simulations.
Total ionization dose radiation tests results of the epoch timing system with sub-picosecond resolution and stability for its applications in space missions
Authors: Prochazka Ivan , Blazej Josef , Kodet Jan
Published: September 2022

We report on the concept, design, and tests of a New Picosecond Event Timer (NPET) device and its response to the total ionizing dose. These radiation tests aimed to verify that the existing version of the NPET device may be used in space missions. The device was subjected to radiation of a total dose of 74 Gy provided by a 60Co source. The epoch timing part of the device was not detectably affected by the radiation dose. After the radiation dose, the epoch timing of single measurement resolution is better than 0.9 ps with the overall timing stability characterized by Time Deviation being better than 5 fs for averaging times of 100 s. The completed device tests and results indicate the possibility of using the existing version of the New Pico Event Timing device electronics for a space mission in which the total radiation dose will not exceed 74 Gy value.
Shock resistance capability of multi-principal elemental alloys as a function of lattice distortion and grain size
Authors: Singh Sandeep Kumar , Parashar Avinash
Published: September 2022

This article aims to study the shock resistance capability of multi-element alloys. In this study, we utilized nonequilibrium molecular dynamics-based simulations with an embedded atom method potential to predict the deformation governing mechanism in a multi-elemental alloy system subjected to shock loading. The evolution of shock front width, longitudinal stress, shear stress, and dislocation density were investigated for different polycrystalline multi-element systems containing different mean grain sizes of 5, 10, and 18 nm, respectively. In order to quantify the effect of lattice distortion, average atom (A-atom) potential for quinary (high entropy) and ternary (medium entropy) configurations was also developed in this work. The random composition of multi-element alloys was replaced with single atom-based A-atom arrangements to study the effect of lattice distortion on shock resistance capabilities of high entropy alloy and medium entropy alloy. It was predicted from simulations that a higher value of lattice distortion component in the CoCrCuFeNi alloy leads to provide superior resistance against shock wave propagation as compared to the ternary alloy CrFeNi. In nanocrystalline configurations, dislocations, and stacking faults, only dislocations governed the deformation mechanics in monocrystalline configurations. The simulations indicate that grain size significantly affects the rates of generation of secondary/partial dislocations, hence affecting the stresses and the deformation mechanism of the structures.
Thermodynamically consistent modeling of immiscible gas–liquid flow in porous media
Authors: Kou Jisheng , Wang Xiuhua , Salama Amgad , Hu Yunjin
Published: September 2022

Modeling of immiscible gas–liquid two-phase flow with gas compressibility in porous media plays an important role in shale gas production, geological sequestration of carbon dioxide, and underground gas storage. The second law of thermodynamics is universally recognized as an essential principle any promising model should obey. The existing models have no proper concept of free energies for such a problem, thereby failing to obey this law. In this paper, we first introduce free energies to account for the liquid–gas capillarity effect and gas compressibility, and then using the second law of thermodynamics, we rigorously derive a thermodynamically consistent model for immiscible gas–liquid two-phase flow in porous media. The proposed free energy that describes the capillarity effect is verified by the laboratory data. For gas flow, we use molar density rather than pressure as the primary variable and take the Helmholtz free energy density determined by a realistic equation of state to characterize the gas compressibility. Numerical simulation results are also presented to demonstrate the thermodynamical consistency of the model and the applicability to simulate the liquid and gas displacement processes.
Silicon-mediated improvement of biomass yield and physio-biochemical attributes in heat-stressed spinach (
Authors: Khosa Quratulain , Zaman Qamar uz , An Tingting , Ashraf Kamran , Abbasi Asim , Nazir Saba , Naz Riffat , Chen Yinglong
Published: September 2022

Context Defensive action of plants against biotic and abiotic stresses has been augmented by silicon (Si). Spinach (Spinacia oleracea L.) is a nutritious leafy vegetable that is a cold-tolerant but heat-sensitive crop. Aims and methods The ability of exogenous application of Si (0, 2, 4 and 6 mmol L−1 in the form of K2SiO3) to alleviate heat stress in spinach cv. Desi Palak was investigated. After an acclimatisation period, plants were grown with or without heat stress for 15 days, followed by Si treatment for 25 days. Plant growth and physiology were assessed at 65 days after sowing. Key results Heat stress significantly inhibited plant growth, water status and photosynthesis, soluble sugar and protein contents, and osmolyte status in spinach leaves, but increased electrolyte leakage, activities of antioxidant enzymes, and proline content. Application of Si alleviated heat stress by enhancing water status, photosynthetic pigments, soluble proteins and essential minerals, and by reducing damage of the plasma membrane. The accumulation of osmolytes counterbalance the osmotic stress imposed by heat. Conclusions Silicon plays a vital role in alleviating effects of heat stress by improving water status and photosynthetic rate, and accruing osmoprotectants other than proline. Implications Exogenous application of Si is an efficient strategy to boost tolerance of spinach plants to heat stress, having significant impact on growth and productivity of spinach at higher temperatures.
Walking is like slithering: A unifying, data-driven view of locomotion
Authors: Zhao Dan , Bittner Brian , Clifton Glenna , Gravish Nick , Revzen Shai
Published: September 2022

Legged movement is ubiquitous in nature and of increasing interest for robotics. Most legged animals routinely encounter foot slipping, yet detailed modeling of multiple contacts with slipping exceeds current simulation capacity. Here we present a principle that unifies multilegged walking (including that involving slipping) with slithering and Stokesian (low Reynolds number) swimming. We generated data-driven principally kinematic models of locomotion for walking in low-slip animals (Argentine ant, 4.7% slip ratio of slipping to total motion) and for high-slip robotic systems (BigANT hexapod, slip ratio 12 to 22%; Multipod robots ranging from 6 to 12 legs, slip ratio 40 to 100%). We found that principally kinematic models could explain much of the variability in body velocity and turning rate using body shape and could predict walking behaviors outside the training data. Most remarkably, walking was principally kinematic irrespective of leg number, foot slipping, and turning rate. We find that grounded walking, with or without slipping, is governed by principally kinematic equations of motion, functionally similar to frictional swimming and slithering. Geometric mechanics thus leads to a unified model for swimming, slithering, and walking. Such commonality may shed light on the evolutionary origins of animal locomotion control and offer new approaches for robotic locomotion and motion planning.
Extreme hydroxyl amounts generated by thunderstorm-induced corona on grounded metal objects
Authors: Brune William H. , Jenkins Jena M. , Olson Gabrielle A. , McFarland Patrick J. , Miller David O. , Mao Jingqiu , Ren Xinrong
Published: September 2022

Atmospheric electrical discharges are now known to generate unexpectedly large amounts of the atmosphere’s primary oxidant, hydroxyl (OH), in thunderstorm anvils, where electrical discharges are caused by atmospheric charge separation. The question is “Do other electrical discharges also generate large amounts of oxidants?” In this paper, we demonstrate that corona formed on grounded metal objects under thunderstorms produce extreme amounts of OH, hydroperoxyl (HO2), and ozone (O3). Hundreds of parts per trillion to parts per billion of OH and HO2were measured during seven thunderstorms that passed over the rooftop site during an air quality study in Houston, TX in summer 2006. A combination of analysis of these field results and laboratory experiments shows that these extreme oxidant amounts were generated by corona on the inlet of the OH-measuring instrument and that corona are easier to generate on lightning rods than on the inlet. In the laboratory, increasing the electric field increased OH, HO2, and O3, with 14 times more O3generated than OH and HO2, which were equal. Calculations show that corona on lightning rods can annually generate OH that is 10–100 times ambient amounts within centimeters of the lightning rod and on high-voltage electrical power lines can generate OH that is 500 times ambient a meter away from the corona. Contrary to current thinking, previously unrecognized corona-generated OH, not corona-generated UV radiation, mostly likely initiates premature degradation of high-voltage polymer insulators.
Temporal signals drive the emergence of multicellular information networks
Authors: Li Guanyu , LeFebre Ryan , Starman Alia , Chappell Patrick , Mugler Andrew , Sun Bo
Published: September 2022

Coordinated responses to environmental stimuli are critical for multicellular organisms. To overcome the obstacles of cell-to-cell heterogeneity and noisy signaling dynamics within individual cells, cells must effectively exchange information with peers. However, the dynamics and mechanisms of collective information transfer driven by external signals are poorly understood. Here we investigate the calcium dynamics of neuronal cells that form confluent monolayers and respond to cyclic ATP stimuli in microfluidic devices. Using Granger inference to reconstruct the underlying causal relations between the cells, we find that the cells self-organize into spatially decentralized and temporally stationary networks to support information transfer via gap junction channels. The connectivity of the causal networks depends on the temporal profile of the external stimuli, where short periods, or long periods with small duty fractions, lead to reduced connectivity and fractured network topology. We build a theoretical model based on communicating excitable units that reproduces our observations. The model further predicts that connectivity of the causal network is maximal at an optimal communication strength, which is confirmed by the experiments. Together, our results show that information transfer between neuronal cells is externally regulated by the temporal profile of the stimuli and internally regulated by cell–cell communication.
KidA, a multi-PAS domain protein, tunes the period of the cyanobacterial circadian oscillator
Authors: Kim Soo Ji , Chi Chris , Pattanayak Gopal , Dinner Aaron R. , Rust Michael J.
Published: September 2022

The cyanobacterial clock presents a unique opportunity to understand the biochemical basis of circadian rhythms. The core oscillator, composed of the KaiA, KaiB, and KaiC proteins, has been extensively studied, but a complete picture of its connection to the physiology of the cell is lacking. To identify previously unknown components of the clock, we used KaiB locked in its active fold as bait in an immunoprecipitation/mass spectrometry approach. We found that the most abundant interactor, other than KaiC, was a putative diguanylate cyclase protein predicted to contain multiple Per-Arnt-Sim (PAS) domains, which we propose to name KidA. Here we show that KidA directly binds to the fold-switched active form of KaiB through its N-terminal PAS domains. We found that KidA shortens the period of the circadian clock both in vivo and in vitro and alters the ability of the clock to entrain to light-dark cycles. The dose-dependent effect of KidA on the clock period could be quantitatively recapitulated by a mathematical model in which KidA stabilizes the fold-switched form of KaiB, favoring rebinding to KaiC. Put together, our results show that the period and amplitude of the clock can be modulated by regulating the access of KaiB to the fold-switched form.
Structural mechanism for bidirectional actin cross-linking by T-plastin
Authors: Mei Lin , Reynolds Matthew J. , Garbett Damien , Gong Rui , Meyer Tobias , Alushin Gregory M.
Published: September 2022

To orchestrate cell mechanics, trafficking, and motility, cytoskeletal filaments must assemble into higher-order networks whose local subcellular architecture and composition specify their functions. Cross-linking proteins bridge filaments at the nanoscale to control a network’s μm-scale geometry, thereby conferring its mechanical properties and functional dynamics. While these interfilament linkages are key determinants of cytoskeletal function, their structural mechanisms remain poorly understood. Plastins/fimbrins are an evolutionarily ancient family of tandem calponin-homology domain (CHD) proteins required to construct multiple classes of actin networks, which feature diverse geometries specialized to power cytokinesis, microvilli and stereocilia biogenesis, and persistent cell migration. Here, we focus on the structural basis of actin network assembly by human T-plastin, a ubiquitously expressed isoform necessary for the maintenance of stable cellular protrusions generated by actin polymerization forces. By implementing a machine-learning–enabled cryo-electron microscopy pipeline for visualizing cross-linkers bridging multiple filaments, we uncover a sequential bundling mechanism enabling T-plastin to bridge pairs of actin filaments in both parallel and antiparallel orientations. T-plastin populates distinct structural landscapes in these two bridging orientations that are selectively compatible with actin networks featuring divergent architectures and functions. Our structural, biochemical, and cell biological data highlight inter-CHD linkers as key structural elements underlying flexible but stable cross-linking that are likely to be disrupted by T-plastin mutations that cause hereditary bone diseases.
Caenorhabditis elegans
sine oculis/SIX-type homeobox genes act as homeotic switches to define neuronal subtype identities
Authors: Cros Cyril , Hobert Oliver
Published: September 2022

The classification of neurons into distinct types reveals hierarchical taxonomic relationships that reflect the extent of similarity between neuronal cell types. At the base of such taxonomies are neuronal cells that are very similar to one another but differ in a small number of reproducible and select features. How are very similar members of a neuron class that share many features instructed to diversify into distinct subclasses? We show here that the six very similar members of the
Caenorhabditis elegans
IL2 sensory neuron class, which are all specified by a homeobox terminal selector,
unc-86/BRN3
, differentiate into two subtly distinct subclasses, a dorsoventral subclass and a lateral subclass, by the toggle switch–like action of the sine oculis/SIX homeobox gene
unc-39
.
unc-39
is expressed only in the lateral IL2 neurons, and loss of
unc-39
leads to a homeotic transformation of the lateral into the dorsoventral class; conversely, ectopic
unc-39
expression converts the dorsoventral subclass into the lateral subclass. Hence, a terminal selector homeobox gene controls both class- as well as subclass-specific features, while a subordinate homeobox gene determines the ability of the class-specific homeobox gene to activate subtype-specific target genes. We find a similar regulatory mechanism operating in a distinct class of six motor neurons. Our findings underscore the importance of homeobox genes in neuronal identity control and invite speculations about homeotic identity transformations as potential drivers of evolutionary novelty during cell-type evolution in the brain.
A corpus-based study of anglicized neologisms in Korea
Authors: Kim Eun-Young Julia
Published: September 2022

This study examines usage changes of English-based loanwords and Korean replacement words promoted by the National
Institute of Korean Language in a six-year span, using two corpora. It focuses on 18 Korean and anglicized word pairs appearing on
the National Institute of Korean Language’s website that purportedly showcase the Institute’s successful efforts to curtail the
usage of English words by promoting Korean replacement words. The results indicate that promoting Korean does not necessarily
decrease the usage of English, and that the usage of English-based words seems to increase in conjunction with the Korean words.
Several Korean words promoted by the National Institute of Korean Language have extremely low frequencies, and some loanwords are
being used with various meanings. Commentaries are provided to explain various patterns of observed usage change.
Diminished cell proliferation promotes natural killer cell adaptive-like phenotype by limiting FcεRIγ expression
Authors: Shemesh Avishai , Su Yapeng , Calabrese Daniel R. , Chen Daniel , Arakawa-Hoyt Janice , Roybal Kole T. , Heath James R. , Greenland John R. , Lanier Lewis L.
Published: September 2022

Human adaptive-like natural killer (NK) cells express low levels of FcεRIγ (FcRγ−/low) and are reported to accumulate during COVID-19 infection; however, the mechanism underlying and regulating FcRγ expression in NK cells has yet to be fully defined. We observed lower FcRγ protein expression in NK cell subsets from lung transplant patients during rapamycin treatment, suggesting a link with reduced mTOR activity. Further, FcRγ−/low NK cell subsets from healthy donors displayed reduced mTOR activity. We discovered that FcRγ upregulation is dependent on cell proliferation progression mediated by IL-2, IL-15, or IL-12, is sensitive to mTOR suppression, and is inhibited by TGFβ or IFNα. Accordingly, the accumulation of adaptive-like FcRγ−/low NK cells in COVID-19 patients corresponded to increased TGFβ and IFNα levels and disease severity. Our results show that an adaptive-like NK cell phenotype is induced by diminished cell proliferation and has an early prognostic value for increased TGFβ and IFNα levels in COVID-19 infection associated with disease severity.
Performance investigation of Ti
x
N
x−1O2 MXene (x = 2, 3, 4) as anode materials for Na-ion batteries by first-principles calculation
Authors: Zhang Wenshu , Qu Jianping , Wang Xudong , Huang Hao , Yao Man
Published: September 2022

The number of MXene layers plays a crucial role in their performance when they are used as anode materials for sodium-ion batteries. Herein, Ti-based nitride MXenes with different layers, Ti
x
N
x−1O2 MXene (x = 2, 3, 4) structures, were constructed to calculate the structural stability of their precursor, electronic properties after etching, and sodium storage behavior compared with the common Ti2CO2 and Ti3C2O2 MXene. First-principles calculations indicate that nitride MXenes possess a better rate capability than carbide MXenes of the same thickness. Moreover, the barrier for Na diffusion on the Ti2NO2 MXene surface (0.114 eV) is lowest. Meanwhile, comparing the properties of three nitride MXenes with different thicknesses, Ti2NO2 MXene performs relatively well with a high theoretical capacity with 756 mAh g−1 and a lower open circuit voltage of 1.1 V. In conclusion, the performance improvement of nitride MXene is not linear with thickness, because that of Ti3N2O2 MXene is relatively weaker. This work lays the foundation for the feasibility of Ti3N2T
x
experimental preparation and provides corresponding evidence on the choice of MXene thickness. More attention should be paid to the etching method for Ti2NT
x
MXene.
Excitonic properties in a double-layer graphene
Authors: Do Thi-Hong-Hai , Bui Duc-Tinh , Phan Van-Nham
Published: September 2022

This paper investigates theoretically the excitonic condensation state at zero temperature in a double-layer graphene structure. In the framework of the unrestricted Hartree–Fock approximation, the electron-hole system in the structure described in the two-band electronic model is analyzed and one finds a set of self-consistent equations determining the excitonic order parameter. The optical properties of the excitonic condensation state then are examined in the Kubo linear optical response theory. Our results indicate that in the case of sufficiently large Coulomb interaction, the BEC excitonic condensation state might occur at low electronic excitation density. By turning the external electric field, the superfluid state stabilizes in the BCS-type excitonic condensate. The optical conductivity spectrum also provides us more insight into the excitonic condensation states.
Vector dark radiation and gravitational-wave polarization
Authors: Miravet Alfredo D. , Maroto Antonio L.
Published: September 2022

We consider conformal vector models which could play the role of a cosmological dark
radiation component. We analyse the propagation of gravitational waves in the presence of this
vector background and find a suppression in the tensor transfer function at large scales. We also
find that although the cosmological background metric is isotropic, anisotropies are imprinted in
the tensor power spectrum. In addition, the presence of the background vector fields induces a net
polarization of the gravitational wave background and, for certain configurations of the vector
field, a linear to circular polarization conversion. We also show that this kind of effects are
also present for vector models with more general potential terms.
Inflation with two-form field: the production of primordial black holes and gravitational waves
Authors: Fujita Tomohiro , Nakatsuka Hiromasa , Obata Ippei , Young Sam
Published: September 2022

Antisymmetric tensor field (two-form field) is a ubiquitous component in string theory and generally couples to the scalar sector through its kinetic term. In this paper, we propose a cosmological scenario that the particle production of two-form field, which is triggered by the background motion of the coupled inflaton field, occurs at the intermediate stage of inflation and generates the sizable amount of primordial black holes as dark matter after inflation. We also compute the secondary gravitational waves sourced by the curvature perturbation and show that the resultant power spectra are testable with the future space-based laser interferometers.
Dynamics of phase inclusion during rotational oscillations of simply connected annulus
Authors: Karpunin I E , Kozlov N V , Zimasova A R
Published: September 2022

The dynamics of a phase inclusion in a coaxial liquid layer divided with a radial partition is studied experimentally. The working volume of the container is filled with a viscous liquid, inside which an air bubble, immiscible with the main phase, is injected. This inclusion has a lower density than the surrounding liquid does. The container performs rotational oscillations as a whole with the zero average rotation. Such a motion brings to the generation of a harmonically oscillating azimuthal shear flow, which, as a consequence, excites the oscillations of the phase inclusion. During the bubble’s oscillations, the displacement of its geometric center follows the sinusoidal law. On the background of such a motion a periodic deformation of the bubble is observed, i.e. the phase boundary starts oscillating. A new and surprising result of the experiments is found, when the light bubble sinks and takes a quasi-steady position near the inner wall of the layer.
The influence of heat release on the dynamics of a porous material saturation in the course of gaseous silicon condensation
Authors: Demin V A , Maryshev B S , Menshikov A I
Published: September 2022

The results of a direct numerical simulation are presented which describe the specific process of a porous medium high-temperature siliconizing. The calculations were performed taking into account the diffusion, the weak pressure gradient across a workpiece and the heat release during the condensation of gaseous silicon in pores. Phenomenological formulas for the evaporation and condensation coefficients in dependence on temperature are offered. An evolutionary equation for the temperature distribution in a sample is derived, which takes into account these processes. Mathematical statement of the problem is based on the modified MIM-model with addition Darcy’s law. Numerical modeling has been fulfilled by the finite difference method using an explicit scheme. It is shown that the heating release in the sample slows down the process of particle settling. The results of numerical simulation are consistent qualitatively with known experimental data.
Liquid free boundary in vertical gap subject to modulated rotation
Authors: Kozlov V G , Petukhova M A
Published: September 2022

The effect of rotation velocity modulation on the equilibrium shape of the liquid-air interface in a vertical slot gap rotating around a horizontal axis is studied experimentally. The case is considered when the modulation frequency coincides with the rotation frequency. It is found that in this case, velocity modulation leads to a violation of the axial symmetry of the interface formed by the centrifugal force of inertia. The displacement of the center of symmetry of the interface increases linearly with the amplitude of the velocity modulation and decreases quadratically with the speed of rotation. It is shown that the detected phenomenon is explained by the averaged effect of an external gravitational field on a fluid in a rotating frame of reference.
Modelling of bone tissue adaptation in Ilyushin's spaces
Authors: Tverier V M , Chikova T N
Published: September 2022

Some bones of the human skeleton are porous inside and resemble a sponge. The cancellous bone tissue forms the epiphyses of the long bones and practically the entire volume of the cancellous bones. It is known that the structural units of the spongy substance – trabeculae, are located along the lines of action of the greatest mechanical loads created by the muscles attached to the skeleton. If the load during life changes due to some reason, for example, injuries, the characteristics of the profession or lifestyle, then the cancellous bone rebuilds its structure in order to withstand this load. In the presented study, a model is proposed for describing the process of cancellous bone tissue adaptation in the geometric Ilyushin’s spaces
Application of the automatic code generation and symbolic computation techniques to numerical solution of PDE problems
Authors: Khlybov Oleg A
Published: September 2022

A software package for the numerical solution of systems of linear and nonlinear partial differential equations by grid methods is presented, which combines symbolic computations and automatic code generation techniques. Discretization of differential equations is carried out by the methods of finite volumes and finite differences on two-dimensional and three-dimensional regular rectangular grids. The solution of the systems of nonlinear algebraic equations obtained as a result of discretization is performed by Newton’s method with employment of third-party SLAE solvers. The generated code can exploit shared and distributed memory parallelisms and take advantage of heterogeneous computations. The results of the numerical solutions of two sample CFD problems of the fluid flow generation in a cylindrical cavity filled with electrically conductive liquid driven the by traveling and rotating magnetic fields are presented.
Stability of a system of circular rings reinforced with inextensible threads
Authors: Andryukova V. Yu. , Tarasov V. N.
Published: September 2022

The paper deals with the problems of stability for a system of circular rings interconnected in such a way that the displacements of these rings, and the rotation angles of their sections at some points, coincide. This has been reduced to a certain variational problem with restrictions on the functions in question in the form of linear equations, and Fourier series are used to obtain a finite-dimensional approximation. The paper also presents the stability problem for a system of circular rings reinforced by inextensible threads that cannot resist compressive forces. In this case, constraints in the form of inequalities arise, and after finite-dimensional approximation the problem reduces to finding the bifurcation points for a nonlinear programming problem in the presence of inequality constraints.
Influence of the shape on the hydraulic resistance of bypass channels inside a smart pig for low pressure gas pipeline inspection
Authors: Muginov R R , Pavlov D A , Peshcherenko M P , Peshcherenko S N , Perminov A V
Published: September 2022

The in-line smart pig for gas pipeline diagnostics is driven by the pumped gas and performs quality diagnostics only if its speed is constant, when the information reading is uniform along the length of the pipeline. In a low-pressure gas pipeline, if there are inhomogeneities on its walls, the condition of the pig speed constancy is easily broken, as the force of resistance to the pig movement on the stoppers is comparable with the difference of pressure forces acting on its ends. A central bypass channel of constant cross-section is usually used to control the pig velocity. The paper shows insufficiency of such method of regulation, leading to noticeable flow pulsations at the outlet of the channel. The use of variable cross-section of the bypass channel along its length in the form of a Laval nozzle to reduce flow pulsations is proposed. The numerical simulation of gas flow in Laval nozzles of different configuration is performed; it is shown that for all considered nozzles, the pressure pulsation at the channel outlet is 20-30 times less than that in the cylindrical channel, which simplifies the velocity control of such pig. However, it is not possible to completely avoid detachment of the flow from the walls of the expanding part of the nozzle, so in order to reduce the area of the detachment zone and reduce the flow resistance force, additional peripheral bypass channels connecting the inlet end of the pig with the diffuser section of the central bypass are added. Thus, a 40% reduction of gas flow resistance force through the bypass compared to the cylindrical bypass is obtained.
Vibroconvective heat transfer in cylindrical container with oscillating elastic boundaries
Authors: Saidakov V , Plouraboué F , Kozlov N
Published: September 2022

Heat transfer in a horizontal annular region filled with the viscous fluid is studied experimentally. The external boundary of the working volume is formed by an elastic silicone shell, while the internal one – by a cylindrical copper heater. The walls of the shell are brought into symmetric oscillatory motion by two linear servomotors. The temperature outside the external cylinder is maintained constant by pumping the thermally stabilized liquid. The experiments are conducted with the low heating power that corresponds to relatively low values of the Rayleigh number. This allows maintaining a regime, in which the forced, vibrational convection is the main mechanism of heat transfer. Theoretical analysis of the experimental results shows that the structure of the fluid flows is determined by the competition between the free, thermal convection and the forced one – the steady streaming generated by vibration. At sufficiently high intensity of oscillations, the forced convection dominates and leads to the increase of the heat transfer rate.
Experimental study of light sphere motion in liquid in rotating tilted cylinder
Authors: Zvyagintseva E A , Kudymova E M , Romanets V Ya , Kozlov V G
Published: September 2022

The motion of a light spherical body in a rotating tilted cylindrical cavity with liquid is studied experimentally. The rotation rate and angle of inclination of the cuvette, the viscosity of the liquid and the characteristics of the body vary. It is shown that with an increase in the rate of the cell rotation, the velocity of the body’s ascent decreases. An increase in the angle of inclination of the cylinder relative to the vertical also leads to a decrease in the ascent rate of the body. A paradoxical behaviour of the body is demonstrated: with an increase in the viscosity of the liquid, the velocity of the body’s ascent increases while maintaining other parameters (rotation rate, size, density of the body and the angle of inclination). The results of investigations at various angles of inclination, properties of liquid and the body are generalized on the plane of two control dimensionless parameters. Comparison with theory and with experimental results of other authors in the case of vertical orientation of the cavity demonstrates good agreement. It was found that during ascent, the body performs differential rotation relative to the cavity, the rate of which depends on the axial coordinate of the body.
On disturbances of the geostrophic flow influenced by volume sources of buoyancy and momentum
Authors: Ingel Lev Kh.
Published: September 2022

As is well known, flows in a free atmosphere outside a narrow equatorial zone are characterized by a geostrophic regime. For several applications, it is of interest to estimate the disturbances of the geostrophic wind caused by the action of sources of heat and/or momentum. One possible example is associated with manifestations of internal gravitational waves. A linear analytical model of the geostrophic flow disturbances of a stratified rotating medium caused by the action of stationary sources of momentum and/or buoyancy is considered. The model makes it possible to estimate explicitly the amplitudes of such disturbances depending on the parameters of the sources and the characteristics of the medium.
Investigation of the conditions for the development of waves at the interface of water masses of different densities
Authors: Lyubimova T P , Parshakova Ya N
Published: September 2022

The influence of differences in the hydrochemical characteristics of the waters of merging rivers on the formation of density currents and the behavior of the density jump layer is studied numerically. The problem is solved for the velocity regimes of the confluent Chusovaya and Sylva rivers (Russian Federation), which are characterized by significantly different salinity values. To study the specific features of layered structures, numerical simulation is performed in the framework of a two-dimensional approach. The calculations are carried out for a section of the Chusovaya River with a length of 300 m, located downstream from confluence of the Chusovaya and Sylva rivers. The Chusovskoy water intake of the city of Perm is located on this site. In the winter-spring season, in this area a regime is established in which a stable layer of density and velocity jumps is observed. With the confluence parameters typical of the winter low water season in the area of the Chusovskoy water intake, 8 km below the confluence point, field measurements detected fluctuations in the concentration and flow velocity in the density jump layer. The two-dimensional numerical simulations performed in the present work also showed the presence of velocity and concentration fluctuations in the jump layer. We found that vortex structures are formed in the jump layer, leading to fluctuations in the concentration in time at a given point and to the formation of a wave structure of the concentration field at different times.
Numerical study of skewness, kurtosis and variance of droplet-size distribution in air-assisted atomizer
Authors: Mingalev S , Khudyakov D
Published: September 2022

We study the approach to calculating the scale and shape parameters of the Weibull droplet-size distribution by means of the skewness, kurtosis and variance, obtained by simulation of atomization in an air-assisted atomizer with different viscosities, densities, flow rates and surface tensions of atomizing liquid. Such approach evades necessity to determine the shift parameter and to use the approximation of distribution obtained from the calculation by the Weibull distribution. The major obstacle to an application of it in processing the data about the atomization of droplets (obtained through the calculation) is the high level of fluctuations of skewness and kurtosis in case of small averaging time.
On the efficiency of convective mixing in a Y-shaped channel
Authors: Bratsun Dmitry , Pismen Len , Siraev Ramil
Published: September 2022

Continuous-flow microfluidic devices are widely used in microbiology, fine organic synthesis, pharmaceuticals, biomedicine, etc. Most applications require rapid mixing of the fluids that pass through the microfluidic chip. The mechanism of natural diffusion is not always efficient due to limitations on the length of the channel. In this work, we numerically study the efficiency of using various mechanisms of natural convection for the mixing of fluids entering the microfluidic chip. Solutions typically differ in buoyancy and diffusion rates of dissolved components, making them sensitive to gravity-dependent instabilities such as Rayleigh-Taylor convection, double diffusion and diffusion layer convection. We consider a Y-shaped microchannel, which is, on the one hand, the simplest, and, on the other hand, a typical element of a microfluidic network. We assume that two miscible solutions independently flow into a common channel where they come into contact. For each type of instability, we numerically estimated the characteristic channel length, after which complete mixing of the solutions occurs. The simulations were performed in the framework of both 2D and 3D models. Finally, we compare the numerical results with the experimental data obtained recently.
Influence of substrate properties on a fluid drop’s free translational oscillations
Authors: Alabuzhev A A
Published: September 2022

The liquid drop’s natural translational oscillations are considered. The equilibrium form of this drop is a circular cylinder. Its axis of symmetry is perpendicular to two parallel solid substrates. The properties (wetting, roughness etc.) of these surfaces differ from each other. The drop is in another liquid. The contact angles’s changes are linearly proportional to the velocities of both contact lines. The Fourier series form by Laplace’s operator eigenfunctions are used for the problem solution. A system of complex equations of eigenvalue problem is solved numerically. The main frequency of the translational mode becomes zero after a critical Hocking’s parameter in situation of identical plates. The branching point of a decrement curve agrees with the zero point of a fundamental frequency. This frequency may not be vanishing on nonidentical surfaces of plates.
Gamma Heating Evaluation of Silicide RSG-GAS Multipurpose Reactor
Authors: Rohanda A , Waris A , Kurniadi R , Bakhri S
Published: September 2022

In research reactor, gamma heating deposited in the samples is an important issue because it is related to the samples and the reactor operational safety. Multi Purpose Reactor (MPR) 30 MWth or its called Reaktor Serba Guna G.A. Siwabessy (RSG-GAS) is a research reactor that play a role as a place to irradiate various target material type. RSG-GAS has been operating since 1987 and the last measurement of gamma heating in the core was conducted around twenty years ago in oxide core. In 1996, RSG-GAS core was converted from oxide fuel type to silicide fuel type. The purpose of the conversion are to improve the performance and efficiency of RSG-GAS. As part of RSG-GAS irradiation facilities safety analysis, the gamma heating measurement was re-conducted in order to obtain latest data as benchmark data in silicide core. This paper presents the results of gamma heating measurement of LEU silicide RSG-GAS core in Central Irradiation Position (CIP) at 15 MW and 30 MW power level using gamma calorimeter. There were four types of calorimeter used, which were calorimeter with graphite (C) sample, iron (Fe) sample, aluminum (Al) sample and zirconium (Zr) sample. Gamma heating calculations using GAMSET code were performed to verify the measurement results. The measurement results are lower than the GAMSET results and the gamma heating value increases in proportion to the increase of calorimeter sample atomic number. This results are corresponds to gamma heating benchmarking results of RSG-GAS oxide core. Several optimization efforts both measuring and modeling with GAMSET were conducted as an evaluation and justification of the results. The best optimization results are achieved using the maximum value of the measurement and adjusting the power peaking factor (PPF) distribution. The calculated gamma heating value optimization results at 15 MW power are 2.78 W/g (C sample), 2.74 W/g (Al sample), 3.36 W/g (Fe sample) and 4.60 W/g (Zr sample) while at 30 MW power level are 5.57 W/g (C sample), 5.49 W/g (Al sample), 6.75 W/g (Fe sample) and 9.23 W/g (Zr sample). The best optimization results serve as a benchmark data for developing new gamma heating calculation programs based on 18 gamma energy groups.
Simulation of Neutron and Gamma Dose Rate of The TRIGA 2000 Reactor Using Monte Carlo Method
Authors: Rakotovao L.O. , Permana Sidik , Oetami R.H. , Rasito
Published: September 2022

The neutron and gamma radiation doses were calculated from the operation of the 1 MW TRIGA 2000 Reactor in a simulation using the Monte Carlo method with MCNPX and PHITS program. Simulation is done by modelling the geometry of the reactor component materials and running it on a computer. The radiation source in the form of a fission reaction in the reactor core has been simulated using MCNPX to produce a dose of neutron and gamma radiation in the TRIGA 2000 core. Attenuation of neutron and gamma radiation by the reactor building is simulated using the PHITS code so that the neutron and gamma dose rates are obtained on the source, y, and z from reactor core. Interpolation of dose rate curves on large material thicknesses was carried out with the TVL neutron and gamma values of the simulation results for each reactor material. The simulation results shows that the gamma neutron dose rate outside the TRIGA 2000 reactor building is still below the dose limit value for radiation workers.