bluuebunny/crossref_metadata_2025 huggingface dataset:
The long noncoding RNA KTN1-AS1 promotes bladder cancer tumorigenesis via KTN1 cis-activation and the consequent initiation of Rho GTPase-mediated signaling
Authors: Hu Xueying , Xiang Liang , He Dong , Zhu Rongrong , Fang Jianing , Wang Zhanwang , Cao Ke
Published: January 2021

Background: Accumulating evidence support the hypothesis that long noncoding RNAs (lncRNAs) are involved in several physiological and pathological conditions, including cancer. Here, we investigated the potential role of lncRNAs in bladder cancer.

Methods: We first looked at available datasets retrieved from the TCGA database and discovered that the lncRNA KTN 1 antisense RNA 1 (KTN1-AS1) was significantly up-regulated in several cancer types including bladder cancer, but was decreased in some other tumors. Therefore, we focused our attention on KTN1-AS1. Using both in vitro and in vivo systems that allowed the modulation of KTN1-AS1 and expression of other relevant proteins, we investigated in-depth the role of KTN1-AS1 in bladder cancer (and the mechanism behind). We further investigated the potential KTN1-AS1-interacting proteins using RNA immunoprecipitation, and explored the KTN1-AS1-related epigenetic landscape (with a particular emphasis on acetylation) using chromatin immunoprecipitation (ChIP) assays.

Results: KTN1-AS1 silencing inhibited the proliferation, invasion, and migration of bladder cancer cells, while KTN1-AS1 overexpression had the obvious opposite effects. Mechanistically, KTN1-AS1 promoted the recruitment of EP300, a histone acetyltransferase that enriched acetylation of histone H3 at lysine 27 (H3K27Ac) in the KTN1 promoter region. This epigenetic modulation contributed to the up-regulation of KTN1, which affected bladder cancer growth and progression via the regulation of Rho GTPase (RAC1, RHOA, and CDC42)-mediated signaling.

Conclusion: Overall, our data support the idea that the lncRNA KTN1-AS1 promotes bladder cancer tumorigenesis via modulation of the KTN1/Rho GTPase axis and is a promising new therapeutic target for the treatment of bladder cancer.
Host cell glutamine metabolism as a potential antiviral target
Authors: Hirabara Sandro Massao , Gorjao Renata , Levada-Pires Adriana Cristina , Masi Laureane Nunes , Hatanaka Elaine , Cury-Boaventura Maria Fernanda , da Silva Eliane Borges , Santos-Oliveira Laiane Cristina dos , Sousa Diniz Vinicius Leonardo , Serdan Tamires Afonso Duarte , de Oliveira Vivian Araujo Barbosa , de Souza Diego Ribeiro , Gritte Raquel Bragante , Souza-Siqueira Talita , Zambonatto Raquel Freitas , Pithon-Curi Tania Cristina , Bazotte Roberto Barbosa , Newsholme Philip , Curi Rui
Published: January 2021

A virus minimally contains a nucleic acid genome packaged by a protein coat. The genome and capsid together are known as the nucleocapsid, which has an envelope containing a lipid bilayer (mainly phospholipids) originating from host cell membranes. The viral envelope has transmembrane proteins that are usually glycoproteins. The proteins in the envelope bind to host cell receptors, promoting membrane fusion and viral entry into the cell. Virus-infected host cells exhibit marked increases in glutamine utilization and metabolism. Glutamine metabolism generates ATP and precursors for the synthesis of macromolecules to assemble progeny viruses. Some compounds derived from glutamine are used in the synthesis of purines and pyrimidines. These latter compounds are precursors for the synthesis of nucleotides. Inhibitors of glutamine transport and metabolism are potential candidate antiviral drugs. Glutamine is also an essential nutrient for the functions of leukocytes (lymphocyte, macrophage, and neutrophil), including those in virus-infected patients. The increased glutamine requirement for immune cell functions occurs concomitantly with the high glutamine utilization by host cells in virus-infected patients. The development of antiviral drugs that target glutamine metabolism must then be specifically directed at virus-infected host cells to avoid negative effects on immune functions. Therefore, the aim of this review was to describe the landscape of cellular glutamine metabolism to search for potential candidates to inhibit glutamine transport or glutamine metabolism.
The stellar halos of ETGs in the IllustrisTNG simulations
Authors: Pulsoni C. , Gerhard O. , Arnaboldi M. , Pillepich A. , Rodriguez-Gomez V. , Nelson D. , Hernquist L. , Springel V.
Published: January 2021

Stellar halos in early-type galaxies (ETGs) are shaped by their accretion and merger histories. We use a sample of 1114 ETGs in the TNG100 simulation of the IllustrisTNG suite with stellar masses 1010.3 ≤ M*/M⊙ ≤ 1012, selected at z = 0 within the range of the g − r colour and λ-ellipticity diagram populated by observed ETGs. We study how the rotational support and intrinsic shapes of the stellar halos depend on the fraction of stars accreted, both overall and separately, by major, minor, and mini mergers. Accretion histories in TNG100 ETGs as well as the final radial distributions of ex-situ stars fexsitu(R) relative to in-situ (“accretion classes”) strongly correlate with stellar mass. Low-mass galaxies have characteristic peaked rotation profiles and near-oblate shapes with rounder halos that are completely driven by the in-situ stars. At high fexsitu, major mergers decrease the in-situ peak in rotation velocity, flatten the V*/σ*(R) profiles, and increase the triaxiality of the stellar halos. Kinematic transition radii do not trace the transition between in-situ- and ex-situ-dominated regions, but for systems with M* > 1010.6 M⊙ the local rotational support of the stellar halos decreases with the local ex-situ fraction fexsitu(R) at fixed M*, and their triaxiality increases with fexsitu(R). These correlations between rotational support, intrinsic shapes, and local fexsitu are followed by fast and slow rotators alike with a continuous and overlapping sequence of properties, but slow rotators are concentrated at the high-fexsitu end dominated by dry major mergers. We find that in ∼20% of high-mass ETGs, the central regions are dominated by stars from a high-redshift compact progenitor. Merger events dynamically couple stars and dark matter: in high-mass galaxies and at large radii where fexsitu ≳ 0.5, both components tend to have similar intrinsic shapes and rotational support, and nearly aligned principal axes and spin directions. Based on these results we suggest that extended photometry and kinematics of massive ETGs (M* > 1010.6 M⊙) can be used to estimate the local fraction of ex-situ stars, and to approximate the intrinsic shapes and rotational support of the co-spatial dark matter component.
Orbital solutions derived from radial velocities and time delays for four Kepler systems with A/F-type (candidate) hybrid pulsators
Authors: Lampens P. , Vermeylen L. , Frémat Y. , Sódor Á. , Skarka M. , Samadi-Ghadim A. , Bognár Zs. , Lehmann H. , De Cat P. , Goswami A. , Dumortier L.
Published: January 2021

Context. The presence of A/F-type Kepler hybrid stars extending across the entirety of the δ Scuti – γ Doradus instability strips and beyond remains largely unexplained. In order to better understand these particular stars, we performed a multi-epoch spectroscopic study of a sample of 49 candidate A/F-type hybrid stars and one cool(er) hybrid object detected by the Kepler mission. We determined a lower limit of 27% for the multiplicity fraction. For six spectroscopic systems, we also reported long-term variations in the time delays (TDs). For four systems, the TD variations are fully coherent with those of the radial velocities (RVs ) and can be attributed to orbital motion.

Aims. We aim to improve the orbital solutions for those spectroscopic systems with long orbital periods (order of 4–6 years) among the Kepler hybrid stars that we continued to observe.

Methods. The orbits are computed based on a simultaneous modelling of the RVs obtained with high-resolution spectrographs and the photometric TDs derived from time-dependent frequency analyses of the Kepler light curves.

Results. We refined the orbital solutions of four spectroscopic systems with A/F-type Kepler hybrid component stars: KIC 4480321, 5219533, 8975515, and KIC 9775454. Simultaneous modelling of both data types analysed together enabled us to improve the orbital solutions (all), obtain more robust and accurate information on the mass ratio (some for the first time), and identify the component with the short-period δ Sct-type pulsations (all). The information gained is maximized when one of the components, generally the one exhibiting the δ Sct-type pulsations, is a fast rotator. In several cases, we were also able to derive new constraints for the minimum component masses. From a search for regular frequency patterns in the high-frequency regime of the Fourier transforms of each system, we found no evidence of tidal splitting among the triple systems with close (inner) companions. However, some systems exhibit frequency spacings that can be explained by the mechanism of rotational splitting.
Ultrasound-Promoted Synthesis of Spirocyclopropanes from Switchable Starting Materials via Azomethine Ylide [3+2]-Cycloaddition
Authors: Yavari Issa , Sheikhi Sara , Sheykhahmadi Jamil , Taheri Zohreh , Halvagar Mohammad Reza
Published: January 2021

An ultrasound-promoted green protocol to access a new series of spirocyclopropanes from indeno[1,2-b]quinoxaline derivatives and azomethine ylides, generated in situ from the iodine-catalyzed reaction of acetophenones as well as of 2-methylquinoline with pyridine in the presence of a base, is described. These transformations proceed via a spirocyclopropanation reaction followed by elimination of pyridine. Clear evidence for the structure of a spirocyclopropane-linked indenoquinoxaline derivative was obtained from single-crystal X-ray analysis. The most important feature of this reaction is the fact it forms three stereogenic centers, one of which is quaternary, with excellent selectivity.
Efficient Synthesis of 7,8-Dihydro-6H-benzo[c]chromen-6-one Derivatives by Base-Mediated Chemoselective Annulation of Alkylidene Malononitriles with α,β-Unsaturated Coumarins
Authors: Alizadeh Abdolali , Farajpour Behnaz , Khanpour Mojtaba
Published: January 2021

An efficient and chemoselective synthesis of biologically valuable 7,8-dihydro-6H-benzo[c]chromen-6-ones is described. In this method, neither a metal catalyst nor expensive starting materials are needed, and the products can be purified by simple filtration and washing with EtOH. Readily available starting materials, green and mild conditions, synthetically useful yields, and operational simplicity are some highlighted advantages of this unprecedented transformation.
Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
Authors: Berkefeld Andreas , Fleischer Ivana , Kathe Prasad M.
Published: January 2021

This report discloses the deallylation of O- and N-allyl functional groups by using a combination of a Ni-H precatalyst and excess Brønsted acid. Key steps are the isomerization of the O- or N-allyl group through Ni-catalyzed double-bond migration followed by Brønsted acid induced O/N–C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
Prevalence and Likelihood Ratio of Six Objective Signs among Good Responders to Natrum muriaticum: Multi-centre Observational Assessment
Authors: Eizayaga José E. , Waisse Silvia , Rutten Lex , Klein-Laansma Christien , Motura Astrid
Published: January 2021

Background The reliability of homeopathic prescriptions may increase through resource to objective signs and guiding symptoms with significant positive likelihood ratio (LR). We estimated LR for six objective signs attributed to the homeopathic medicine Natrum muriaticum (Nat-m).

Methods In this multi-centre observational assessment, we investigated the prevalence of six signs in the general patient population and among good responders to Nat-m in daily homeopathic practice. Next, we calculated LR for these six signs.

Results Data from 36 good responders to Nat-m and 836 general population patients were compared. We found statistically significant positive LR (95% confidence interval) for signs such as lip cracks (1.94; 1.15 to 3.24), recurrent herpes (2.29; 1.20 to 4.37), hairline eruptions (2.07; 1.03 to 4.18), and dry hands (2.13; 1.23 to 3.69).

Conclusions Objective signs with significant positive LR might increase the reliability of homeopathic prescriptions. Further studies are warranted to confirm the validity of this approach.
Venous Thromboembolism in Cancer Patients Undergoing Chemotherapy: Risk Factors and Prevention
Authors: Prandoni Paolo , Campello Elena
Published: January 2021

Ambulatory cancer patients undergoing chemotherapy are at a substantial risk for venous thromboembolism (VTE) over the course of therapy and beyond it. Factors accounting for this risk include the activation of extrinsic and intrinsic coagulation pathways, platelet activation, impaired fibrinolysis, use of catheters, infusion of blood products, and thrombogenic potential of several chemotherapeutic drugs. A few stratification models can help identify patients at a higher risk of chemotherapy-associated VTE, who may benefit from preventive strategies. Although low-molecular-weight heparins (LMWHs) effectively reduce the risk of VTE, current guidelines recommend against their routine use. Based on the results of recent randomized controlled clinical trials, the administration of prophylactic doses of the novel direct oral anticoagulants (DOACs) to ambulatory cancer patients undergoing chemotherapy has the potential to offer an effective and safe protection against VTE, obviating the inconveniences of heparins. Except for patients in whom the novel drugs are unsuitable or are contraindicated, in all other patients LMWHs should be replaced by low-dose DOACs.
Is Standing Coronal Long-Leg Alignment View Effective in Predicting the Extent of Medial Soft Tissue Release in Varus Deformity during Total Knee Arthroplasty?
Authors: Sajjadi Mohammadreza Minator , Okhovatpour Mohammad Ali , Safaei Yaser , Faramarzi Behrooz , Zandi Reza
Published: January 2021

The aim of this study was to assess the predictive value of the femoral intermechanical-anatomical angle (IMA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibia angle (MPTA), femorotibial or varus angle (VA), and joint line convergence angle (CA) in predicting the stage of the medial collateral ligament (MCL) during total knee arthroplasty (TKA) of varus knee. We evaluated 229 patients with osteoarthritic varus knee who underwent primary TKA, prospectively. They were categorized in three groups based on the extent of medial soft tissue release that performed during TKA Group 1, osteophytes removal and release of the deep MCL and posteromedial capsule (stage 1); Group 2, the release of the semimembranosus (stage 2); and Group 3, release of the superficial MCL (stage 3) and/or the pes anserinus (stage 4). We evaluated the preoperative standing coronal hip-knee-ankle alignment view to assessing the possible correlations between the knee angles and extent of soft tissue release. A significant difference was observed between the three groups in terms of preoperative VA, CA, and MPTA by using the Kruskal–Wallis test. The extent of medial release increased with increasing VA and CA as well as decreasing MPTA in preoperative long-leg standing radiographs. Finally, a patient with a preoperative VA larger than 19, CA larger than 6, or MPTA smaller than 81 would need a stage 3 or 4 of MCL release. The overall results showed that the VA and MPTA could be useful in predicting the extent of medial soft tissue release during TKA of varus knee.
Comparison of Minimally Invasive Operative Treatment with Conservative Treatment for Acute, Minimally Displaced Scaphoid Fractures at 12 Months' Follow-up
Authors: Fyllos Apostolos , Komnos George , Koutis Athanasios , Bargiotas Konstantinos , Varitimidis Sokratis , Dailiana Zoe
Published: January 2021

Background Minimally displaced scaphoid fractures can be challenging to diagnose and treat. Cannulated scaphoid screws have made percutaneous stabilization highly effective.

Questions Would minimally invasive operative treatment of minimally displaced scaphoid fractures yield faster return to work when compared with patients treated conservatively? How do functional and patient satisfaction scores compare between the two groups at 12-months follow-up?

Patients and Methods Records from 18 patients (mean age 28.6 years) treated surgically were retrospectively reviewed and compared with a group of 10 patients (mean age 33.3 years, p = 0.74) treated nonoperatively. Inclusion criteria were a minimum follow-up period of 12 months and radiographic union. Time to return to work was compared between groups. At 12 months' follow-up, wrist range of motion (ROM) and grip strength were compared, as well as pain, satisfaction, and overall wrist function were evaluated by the visual analogue scale (VAS) and the Mayo modified wrist score (MMWS).

Results The mean time to return to work for the operated group was 39.75 days, while for the nonoperated group it was 88.14 days (p = 0.002). At the 12 months' follow-up, mean ROM, grip strength, and VAS score did not differ between groups. The mean MMWS was 98.75 for the operated group and 87.5 for the nonoperated group, indicating a better result in patients treated operatively (p = 0.03). In addition, two failures of instrumentation were recorded, a seldom seen complication.

Conclusion Percutaneous fixation of minimally displaced scaphoid fractures allows faster return to work and leaves patients more satisfied with their wrist function compared with plaster immobilization at 12 months' follow-up.

Level of evidence This is a Level III, retrospective, case–control study.
High Incidence of Osteoarthritis Observed in Patients at Short- to Midterm Follow-Up after Delayed Multiligament Knee Reconstruction
Authors: Sobrado Marcel Faraco , Giglio Pedro Nogueira , Bonadio Marcelo Batista , Pecora Jose Ricardo , Gobbi Riccardo Gomes , Angelini Fabio Janson , Helito Camilo Partezani
Published: January 2021

The aim of this study was to evaluate the incidence of knee osteoarthritis, failure rate of reconstruction, and clinical outcomes of patients with chronic multiligament knee injuries subjected to surgical treatment. Sixty-two patients with chronic knee dislocation subjected to multiligament reconstruction between April 2008 and July 2016 were evaluated, with a minimum follow-up of 24 months. Anteroposterior and lateral radiographs were performed in the pre- and last postoperative evaluation; the progression of degenerative changes according to the Kellgren-Lawrence classification (KL) was assessed. The Schenck classification, Knee Injury and Osteoarthritis Outcome Score (KOOS), time between injury and surgery, type of postoperative rehabilitation protocol (brace vs. external fixator), and physical examination for ligament instability were also evaluated. Univariate and multivariate analysis were performed, p <0.05 was considered significant. Fifty-two (83.9%) patients were men and 16.1% (n = 10) were women, with a mean age of 38.8 ± 1.3 years. The time from injury to surgery was 31.1 ± 6.1 months, and the follow-up time was 6.1 ± 0.5 years. The mean final KOOS was 79.3 ± 10.4 and the overall reconstruction failure occurred in 25.8%. Of all patients, 64.5% (n = 40) presented a KL classification of ≥2 and were defined as having radiographic osteoarthritis (OA). As 11.7% (n = 7) also presented arthritis in the contralateral knee, in 53.2% (n = 33) the progression was most likely due to the initial injury. The failure of ligament reconstruction or residual instability was present in 15 (35.7%) of patients with OA, and only one patient (4.5%) without OA. In the multivariate analysis, only reconstruction failure was an independent predictor of OA (odds ratio = 13.2 [p = 0.028]). There is a high incidence of knee OA following ligament reconstruction for chronic multiligament knee injuries. Ligament reconstruction failure was the only independent predictor for the development of OA in our study.
FcRn is a CD32a coreceptor that determines susceptibility to IgG immune complex–driven autoimmunity
Authors: Hubbard Jonathan J. , Pyzik Michal , Rath Timo , Kozicky Lisa K. , Sand Kine M.K. , Gandhi Amit K. , Grevys Algirdas , Foss Stian , Menzies Susan C. , Glickman Jonathan N. , Fiebiger Edda , Roopenian Derry C. , Sandlie Inger , Andersen Jan Terje , Sly Laura M. , Baker Kristi , Blumberg Richard S.
Published: January 2021

IgG immune complexes (ICs) promote autoimmunity through binding fragment crystallizable (Fc) γ-receptors (FcγRs). Of these, the highly prevalent FcγRIIa (CD32a) histidine (H)-131 variant (CD32aH) is strongly linked to human autoimmune diseases through unclear mechanisms. We show that, relative to the CD32a arginine (R)-131 (CD32aR) variant, CD32aH more avidly bound human (h) IgG1 IC and formed a ternary complex with the neonatal Fc receptor (FcRn) under acidic conditions. In primary human and mouse cells, both CD32a variants required FcRn to induce innate and adaptive immune responses to hIgG1 ICs, which were augmented in the setting of CD32aH. Conversely, FcRn induced responses to IgG IC independently of classical FcγR, but optimal responses required FcRn and FcγR. Finally, FcRn blockade decreased inflammation in a rheumatoid arthritis model without reducing circulating autoantibody levels, providing support for FcRn’s direct role in IgG IC-associated inflammation. Thus, CD32a and FcRn coregulate IgG IC-mediated immunity in a manner favoring the CD32aH variant, providing a novel mechanism for its disease association.
Factors Influencing Ultrasonic Wave Propagation in Tourmaline
Authors: Gai Xinghui , Chen Kairen , Yang Dewu , Zhou Guojun , Zhao Changchun , Zhao Pengfei , Dong Pengsheng , Fan Zhenjun
Published: January 2021

P-wave propagation velocity in tourmaline is related to its microstructure, chemical composition, temperature, and other factors. The effects of tourmaline density, FeO contents, and temperature on P-wave propagation were studied in this paper. The results show that the temperature affects P-wave velocity due to the temperature dependence of thermal expansion, and elastic and dielectric constants of tourmaline. The propagation velocity of P-wave decreases with increasing porosity or FeO content. The content of FeO in tourmaline can be used as the basis for the determination of different species of tourmaline, which provides an important experimental basis for ultrasonic waves to be used as a nondestructive testing technology to distinguish different types of tourmaline.
A Study on the Nuclear Shell Effects near the Drip Line Region
Authors: Shen Shuifa , Yan Yupeng , He Zhixiong , Song Yaodong , Gao Weiwei , Lan Jieqing
Published: January 2021

A theoretical method which is applied to examine the shell effects is presented, namely, by calculating the particle number fluctuation in the framework of the relativistic mean-field model with the BCS pairing. We find that the size of the particle number fluctuation is related to the nuclear shell structure. Based on this method, the disappearance of conventional magic numbers and the presence of new magic numbers near drip-line region are studied.
Study on Acoustics Abnormal Refraction Based on Generalized Snell’s Law
Authors: Chu Q Q , Hu Y , Lin W
Published: January 2021

In recent years, metamaterials have been used to manipulate wave fronts in various ways, affecting the propagation of waves, and exerting different its application values. Based on the generalized Snell’s law derived from Fermat’s principle, the article takes advantage of the high integration of metamaterials at the sub-wavelength scale to construct an acoustic metasurface artificial structure and expands it to a periodic type. Under the condition of ensuring the constant transmittance when acoustic wave passes through the interface of the two media, through the phase modulation of the acoustic wave on the surface of the structure, the strange phenomenon of abnormal refraction is generated, and the arbitrary manipulation of the wave is realized effectively.
Thermodynamic Process Simulation and Evaluation on Surface-Mounted Evaporative Cooling System
Authors: Shi Yitao , Cao Rui , Ruan Lin
Published: January 2021

The change of exergy has a direct impact on the circulation head of the surface-mounted evaporative cooling system that relies on the change of vapor-liquid density for circulating cooling. In this paper, the circulation system of the surface-mounted evaporative cooling system is taken as the research object. Based on the second law of thermodynamics, an exergy analysis model of main equipment is established to analyze and evaluate the characteristics of exergy change of the system. The research results show that under different thermal loads, the exergy efficiency is less than 70%, the exergy loss in the liquid box is relatively large, and the main irreversible exergy loss in liquid box occurs in the vapor-liquid boiling process, which will restrict the cooling capacity of the system. This study provides a theoretical basis for further optimizing the flow heat transfer process of the surface-mounted evaporative cooling system.
Designing Neutron Shield Material for D-T Neutron Generator
Authors: Li Xianglong , Cong Meilin , Yang Guifu , Su Weihua
Published: January 2021

If hydrogen-rich material is used to shield the 14 MeV neutrons produced by D-T neutron generator whose neutron yield is 108 n/s, its thickness must be more than 74 cm to make dose of neutron radiation less than 0.025 mSv/h. For decrease the thickness, two layers material composed of boron-polyethylene and copper used as 14 MeV neutron shielding material. The calculation result shows that the minimum thickness of the two layers material is 52 cm, in which the thicknesses of copper and boron-polyethylene are 38 cm and 14 cm and the boron concentration is 1.00%.
An Electromagnetic Protection Design Evaluation Algorithm for Complex Electronic Systems Based on Margin Estimation
Authors: Tao Lingjiao , Fan Jieqing , Guo Chunying , Wen Yongzhi , Liu Zhiyong
Published: January 2021

Based on the analysis of random error sources in the design margin evaluation of electromagnetic protection for complex electronic, it is researched on a method of evaluating electromagnetic pulse protection capability, the total error standard deviation evaluation theory is analysed. A new method for evaluating the electromagnetic pulse protection capability of complex electronic systems based on the lower limit estimation of design margin and corresponding reliability and confidence is proposed. So taking the evaluation of electromagnetic protection design interval of a certain type of electronic information system as an example, the application and the qualification conditions of the algorithm are illustrated.
Influence of Mesoscale Vortex on Underwater Low-Frequency Sound Propagation
Authors: Xiao Rui , Lei Fuqiang , Zhu Hanhao , Chen Chao , Xue Yangyang
Published: January 2021

To discuss the effect of an ocean mesoscale vortex on underwater low-frequency sound propagation, a theoretical model of a sound field under the action of an ocean mesoscale vortex was established based on acoustic wave theory and ray theory, using the finite element method. The influences of vortex properties and vortex intensity on the characteristics of sound propagation are discussed. The simulation results indicate that, in a cold vortex, the acoustic convergence zone moves toward the sound source, the span of the convergence zone decreases, and the convergence gain increases. Alternatively, for a warm vortex, the convergence zone moves away from the sound source, the span of the convergence zone increases, the sound rays diffuse, and the convergence gain decreases; the greater the vortex intensity, the greater is the effect on the motion and gain of the convergence region.
Discovery of Four Space Dimensions in a Sphere for Electronic Orbitals in a Neon Shell
Authors: Xu Kunming
Published: January 2021

For the first time we discover four space dimensions in a sphere, namely two periphery points, two semicircular arcs, two hemispherical surfaces, and two spherical solids. When these four geometric elements are compared with electronic orbitals in a neon shell, we draw a conclusion that while 2s orbitals are spherical, three types of 2p orbitals in the X, Y, and Z directions are different in the number of space dimensions. These anisotropic 2p orbitals prompt us to modify Schrödinger’s equation to reflect these fine space gradients. Within the atomic sphere, electrons are transforming from one dimension to another following the rule of calculus implemented by circular functions rather than position movement. An electron may exist in the physical shape of a point, an arc, a surface, or a solid. Eight electrons in the neon shell are undergoing various harmonic oscillations that form a continuous octet cycle. This motion feature is derived from a four-dimensional space harmonic oscillation equation coupled with a one-dimensional time harmonic oscillation equation in synthesis of the modified Schrödinger’s equation. Substantial amount of evidence can be found in organic chemistry where a carbon atom has an anisotropic electron configuration of 2s2px2py2pz. By furnishing a fresh and fundamental spacetime worldview, the quaternity theory may change the direction of quantum mechanics from discrete linear algebra toward continuous dynamic calculus in the future.
The Kinematic Modeling and Simulation of an Adjustable Pivot Point of Six Degree-of-Freedom (DOF) Parallel Robot
Authors: Tan Shuang , Liang Fengchao , Chen Long , Lin Zhe
Published: January 2021

For the pose requirements of secondary mirror in the large aperture space optical remote sensor, the pose adjustment is applied to the pivot point of secondary mirror. So the adjustable pivot point kinematic model must be set up. Based on the characteristics of the pivot point fixed with the moving platform, the corresponding coordinate system is built, and the adjustable pivot point kinematic model is established on the Euler rotation. Then virtual prototype model and the pivot point are built in ADAMS, and the kinematic simulation method is given. Finally, a 6-DOF parallel robot as secondary mirror pose adjustment device of an optical remote sensing system is taken as an example, and the adjustable pivot point kinematic model and ADAMS simulation method are carried out. The results show that the model and simulation method are correct and practical, which can be used in any field of a 6 DOF parallel robot with adjustable pivot point.
Analysis of Observation Performance of a Mobile Coherent Doppler Wind Lidar Using DBS Scanning Mode
Authors: Dong Debao , Yang Shizhi , Weng Ningquan , Zhang Guangyuan , Huang Jing
Published: January 2021

The Coherent Doppler Wind Lidar (CDWL) is one of the important remote sensing devices for atmospheric boundary layer wind field observation, it has broad application prospects in the fields of meteorological monitoring and warning, air pollution transportation and aviation safety. In order to test the observation performance of the CDWL using Doppler beam-swinging (DBS) scanning mode, description of the CDWL is introduced, and the main influencing factors of the CDWL observation accuracy is studied, the comparative observation experiments were carried out at the Anqing National Conventional Sounding Station (30°37″ N, 116°58″ E) during the course of Typhoon Rumbia (No. 18, 2018) from August 16 to August 26, 2018. The results show that: the wind observation accuracy is determined by the carrier-to-noise ratio (CNR) of the CDWL. In the precipitation conditions, the effective data acquisition rates of 1.5km and 2.0km detection height are only 46.2% and 38.8%, respectively and it was even difficult to continue operation. Under clear sky conditions, it could operate continuously and the effective data acquisition rates of 1.5km and 2.0km detection height were 85.4% and 64.4%. In addition, the correlation of wind direction and wind speed between the CDWL and the conventional sounding system (L-band secondary wind-finding radar) was 1.041 and 0.982, and the consistency is good. Based on the sounding, the wind direction and wind speed errors of the CDWL during the comparison experiment were 0.82m/s and 9.3°.
Preparation and Superior Absorbing of Electroless Deposited Ni-P-Fe3O4 Composite Powders
Authors: Li Yixian , Zhu Shaofeng , Zhou Xianzhi , Wang Yaqun
Published: January 2021

In this study, the Ni-P-Fe3O4 composite powders containing about 10% phosphorus were prepared by hydrothermal method. The phase, composition and morphology of the powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The wave absorption properties of the Ni-P-Fe3O4 composite powders were estimated by vector network analyzer (VNA). The results showed that the saturation magnetization and resistivity of the as-obtained Ni-P-Fe3O4 composite powders were significantly reduced, however their dispersion as well as conductivity were improved. The electromagnetic wave absorbed by Ni-P-Fe3O4 composite powders was mainly attributed to the dielectric loss, and the absorption of electromagnetic wave in the low frequency can reach to 90% (the reflection loss is less than -10 dB).
Exploration of Low-Energy Earth-Moon Transfer Orbit Based on Crossing Orbit of Double Three-Body System
Authors: Zhang Juan , Liu Wei , Cao Xiaofei
Published: January 2021

The design of low energy lunar transfer orbit and orbit optimization method based on crossing orbit is studied in this paper. The four-body problem of Sun-Earth-Moon-satellite is decoupled into two three-body problems of Sun-Earth-satellite and Earth-Moon-satellite. Low-energy lunar exploration orbit is designed by changing orbit at a certain intersection field through manifold of two Halo orbit of three-body system. A serial optimization design method for global initial value search and local gradient optimization are designed. When a motion state variable is partially modified, the differential correction method combined with adaptive regression algorithm is adopted. For the splicing points of manifolds of different systems, the velocity vector is modified to make the spacecraft get into the target berthing track, and to obtain the splicing points that can form crossing track of the two three-body systems. An example of orbit design is given to show that the Earth-Moon transfer orbit based on invariant manifold splicing has the characteristics of energy saving and long-time consumption, which can be used for the tasks with large loads and low time requirements. This research provides a method for the design of low energy lunar transfer orbit. It will benefit the energy consuming, material design of spacecraft, and so on.
Non-equilibrium critical behavior of multilayer magnetic nanostructures with a non-magnetic metal substrate
Authors: Boldyreva Marina , Prudnikov Pavel , Prudnikov Vladimir , Mamonova Marina
Published: January 2021

A Monte Carlo simulation of the non-equilibrium behavior of multilayer magnetic nanostructure Co/Cu(100)/Co is realized. Calculations of two-time dependent autocorrelation function for structures relaxing from both low-temperature and high-temperature initial states reveal occurrence of aging within a wide range of temperatures at T ≤ Tc
.
Calculating entropy by Ma’s method for a system of k-mers on a square lattice
Authors: Kokosinskii Denis V , Ulyanov Mikhail V
Published: January 2021

Random walk of rectangular particles on a square lattice leads to a pattern formation when the hard-core interaction between the particles is assumed. To estimate changes in the entropy during this random walk, we propose a modification of Ma’s method. The 2D sliding window technique was used to divide a system under consideration into subsystems. We used Ma’s “coincidence” method to estimate the total number of possible states for such subsystems. In this study, the accuracy of Ma’s method is studied in a simple combinatory model, both experimentally and theoretically. We determine which definition of “coincidence” for this scheme leads to greater accuracy. Ma’s estimate of the number of possible states for a system of k-mers correlates well with the estimate obtained using a “naive” method.
Mathematical model of biological tissue surface based on one dimensional stochastic process of fractional Brownian motion
Authors: Smirnov A , Kovalenko N , Ryabushkin O
Published: January 2021

In this work the model for the profiling of biological tissue surfaces is introduced. The surface was considered as the realization of the stochastic process of the fractional Brownian motion (fBm) with the scale parameter σ and Hurst index H. The contour of the epidermal surface of the normal cut banana peel was studied. The magnified digital photos of the investigated specimens were made using the microscope (spatial resolution 1 μm) with the built-in camera. The function that linearly interpolated the surface contour was derived. The dispersion law of the differences between the values of the interpolating function in the adjacent knots was in good agreement with that one of the fBm stochastic process. The values of σ=0.1 and H=0.806 were obtained.
Computer simulation of single burn transfers between low-Earth and halo orbits in the Sun-Earth system
Authors: Mezentsev Gleb , Aksenov Sergey
Published: January 2021

Halo orbits of Sun-Earth system are utilized in space missions as they allow to maintain the spacecraft in an area that is stationary relative to Sun and Earth. The advantage of halo orbits is their periodicity and their form allowing the spacecraft to avoid the zones of solar interference and the Earth shadow. The transfer between a low-Earth orbit and a halo orbit around a libration point can be realized by a single-burn maneuver, which transfers the spacecraft to an orbit of stable manifold resulting in a halo orbit. An amplitude of halo orbit depends on the altitude of the parking low-Earth orbit at which the transfer maneuver is performed. This work is aimed to explore and systemize the single burn transfer options utilizing single and multiple Earth passing trajectories in the framework of the circular restricted three-body problem. The algorithms providing transfer options for the desired halo orbit and the parking orbit altitude are developed. The transfer trajectories for the Sun-Earth L
1 and L
2 halo orbits in a wide range of out-of-plane amplitudes were constructed and studied. The constructed trajectories were clustered based on the transfer time and the halo orbit amplitude.
Calculation of libration point orbits in the circular restricted three-body problem
Authors: Korneev Alexander , Aksenov Sergey
Published: January 2021

This study investigates possibilities for extension and improvement of algorithms for generation of libration point orbits in the framework of the circular restricted three body problem. Two algorithms for orbit generation based on bisection approach using different ways for evaluation of unstable component of motion are considered. The spacecraft’s state vector is periodically adjusted in such a way that unstable component of motion is neutralized and the trajectory corresponding to the corrected state vector belongs to the central manifold associated with libration point. The first algorithm uses expression for unstable component derived from linearized equations of motion. The second one is based on the procedure of reduction to central manifold, utilizing canonical coordinate transformations to nullify high order monomials in the expansion of Hamiltonian of the system in terms of Legendre polynomials. This allows expressing unstable component as one of generalized coordinates of Hamiltonian system obtained as the result of aforementioned transformation. Evaluation of these techniques proved their applicability for orbit generation. However, the second approach allows generating orbits in greater vicinity of libration point.
Numerical simulation of superplastic bulge forming test
Authors: Zakhariev Ivan
Published: January 2021

Superplastic blow forming is a technology of shell parts production. The development of these processes requires computer simulation which cannot be realized without accurate parameters of the applied material. This characterization can be based on results of free bulging tests. Characterization techniques utilize the models of the dome growth during the bulging test. This study is devoted to the assessing of friction coefficient effect on the linear behavior of normalized thickness - normalized height relation.
Computer simulation of superplastic tensile test
Authors: Mikolaenko Vadim
Published: January 2021

Superplasticity is an ability of polycrystalline materials to archive extremely large deformations, which is utilized in advanced forming technologies demanded mainly in the aerospace industry. Design of such technologies needs an information of the material flow behaviour, which describes the relation of the effective stress on the strain and strain rate taking place during deformation. The most popular experimental method for investigation of the flow behaviour of superplastic materials is tensile testing. The procedure of superplastic tensile testing and interpretation of its results is described by several international standards. At the same time, it is known that the due to flow inhomogeneity in the specimen volume the accuracy of such tests may be violated. Moreover, different standards provide different ratio between the width and the height of the gauge area of a specimen. This work provides the numerical analysis aimed to study how the initial specimen geometry affects the results of tensile tests. A computer program implementing finite element method (FEM) was developed to predict the specimen deformation during the test. A flat specimen is discretized using prismatic elements with specific geometrical constraints reducing the degree of freedom to the order of a plane stressed task. The output stress and strain values were calculated as specified in the ASTM E2448 standard. The effect of the gauge length was studied focusing on the output stress strain curves. The results were compared with the experimental results available in the literature.
Applicability of regularized particles-on-demand method to solve Riemann problem
Authors: Zipunova E , Perepelkina A , Zakirov A
Published: January 2021

The lattice Boltzmann method (LBM) is a promising rapidly evolving simulation tool designed to capture the physics of the mesoscopic flow. But it is well known that the standard LBM is severely restricted to problems with low flow speed and small temperature range. The novel Particle-on-demand method (PonD) allows us to numerically solve the discrete Boltzmann equation for high Mach numbers. But the propagation step becomes more computationally intensive. A large part of the computational cost comes from matrix inversions during the rescaling of discrete distribution functions from one system of reference to another. We propose another method of discrete distribution function rescaling by applying regularization and moment conversion to avoid matrix inversions. This improvement shows drastic acceleration in calculations in comparison with standard PonD. Regularized PonD was applied to solve Riemann problems for a range of parameters. Results obtained by this improved method were compared to results received by the standard PonD and the standard LBM. The conservation of mass, momentum and energy of the new numerical method was studied. The necessary conditions for the stability of the solution were obtained.
Approximation of Multiparticle Distribution Function in Micromagnetic Modeling
Authors: Ivanov Anton , Khilkov Sergey , Elizaveta Zipunova
Published: January 2021

We propose the new system of equations for magnetodynamics. It is based on BBGKY hierarchy and uses a new approximations of mulit-particles distribution functions, which takes nearest-neighbour correlations into account. Thus we call the new system of equations correlational magnetodynamics system (CMD). It consists of well known Landau–Lifshitz–Bloch(LLB) equation complemented with an equation for two-particles correlations. Compared to traditional LLB equation, numerical simulations with CMD produces results that are closer to atomistic simulations.
Immersed boundary simulation of drop stability
Authors: Guskova Maria , Shchur Lev
Published: January 2021

The stability of the quasi-two-dimensional droplet flow is of great importance in microfluidic devices. We check the drop’s stability in the square box using the immersed boundary and lattice Boltzmann methods. We implement two-dimensional equations within the immersed boundary approach in the Palabos programming platform. We check the influence of the boundaries on the drop movement. We estimate fluctuations in the quantities while applying different initial conditions of the linear and angular velocities. We found that the level of fluctuations depends on the symmetrical displacement of drop at the initial state. The effect is connected with the hydrodynamic interaction of drop with the walls.
Exploring the accuracy of the Lattice Boltzmann method
Authors: Zagvozdina Ksenia , Burovski Evgeni
Published: January 2021

Lattice Boltzmann method is a mesoscopic method used for solving hydrodynamics problems of both incompressible and compressible fluids. Although the method is widely used, reliability of the results is unclear. Therefore, we use the method to solve a fundamental problem with a known analytical solution, the Couette flow. We estimate the accuracy of the simulation results obtained by setting different types of spatial grids, boundary conditions, and equilibrium distribution functions. However, the method imposes restrictions on a large number of simulation parameters such as Reynolds and Mach numbers. During simulation we discovered an unexpected behavior of the solution using classical lattice Boltzmann method. In these simulations we find that the conservation law is violated due to an unexpected inflow in the upper corners of the computational domain.
Fast simulation of the LHCb electromagnetic calorimeter response using VAEs and GANs
Authors: Sergeev Fedor , Jain Nikita , Knunyants Ivan , Kostenkov George , Trofimova Ekaterina
Published: January 2021

Modern experiments in high-energy physics require an increasing amount of simulated data. Monte-Carlo simulation of calorimeter responses is by far the most computationally expensive part of such simulations. Recent works have shown that the application of generative neural networks to this task can significantly speed up the simulations while maintaining an appropriate degree of accuracy. This paper explores different approaches to designing and training generative neural networks for simulation of the electromagnetic calorimeter response in the LHCb experiment.
Average cluster size inside sediment left after droplet desiccation
Authors: Zolotarev P A , Kolegov K S
Published: January 2021

In this work, we continue to study the formation of particle chains (clusters) inside the annular sediment during the drying of a colloidal droplet on a substrate. The average value of the cluster size was determined after processing experimental data from other authors. We performed a series of calculations and found the value of the model parameter allowed to get numerical results agreed with the experiment. Also, a modification of the previously proposed algorithm is analyzed here.
Ab initio computational study of the electronic and magnetic properties of the HoNiZ compounds accounting for electronic correlations
Authors: Lukoyanov A V , Gramateeva L N
Published: January 2021

In this paper, the electronic structure and magnetic properties of the ternary intermetallics of the HoNiZ series (Z = Ga, Si, Al) is studied using the LSDA+U first-principles method. An analysis of the densities of electronic states in the compounds HoNiGa, HoNiSi, and HoNiAl with accounting for electronic correlations is performed.