bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary exploration of polytypism in lead halide perovskites
Authors: Li Zhenzhu , Park Ji-Sang , Walsh Aron
Published: August 2021

Beyond the regular perovskite structure based on cubic-close packing exists a range of possible polytypes that we explore using computational chemistry.
The inner flow geometry in MAXI J1820+070 during hard and hard-intermediate states
Authors: De Marco B. , Zdziarski A. A. , Ponti G. , Migliori G. , Belloni T. M. , Segovia Otero A. , Dziełak M. A. , Lai E. V.
Published: August 2021

Context. We present a systematic X-ray spectral-timing study of the recently discovered, exceptionally bright black hole X-ray binary system MAXI J1820+070. Our analysis focuses on the first part of the 2018 outburst, covering the rise throughout the hard state, the bright hard and hard-intermediate states, and the transition to the soft-intermediate state.

Aims. We address the issue of constraining the geometry of the innermost accretion flow and its evolution throughout an outburst.

Methods. We employed two independent X-ray spectral-timing methods applied to archival NICER data of MAXI J1820+070. We first identified and tracked the evolution of a characteristic frequency of soft X-ray thermal reverberation lags (lags of the thermally reprocessed disc emission after the irradiation of variable hard X-ray photons). This frequency is sensitive to intrinsic changes in the relative distance between the X-ray source and the disc. Then, we studied the spectral evolution of the quasi-thermal component responsible for the observed thermal reverberation lags. We did so by analysing high-frequency covariance spectra, which single out spectral components that vary in a linearly correlated way on the shortest sampled timescales and are thus produced in the innermost regions of the accretion flow.

Results. The frequency of thermal reverberation lags steadily increases throughout most of the outburst, implying that the relative distance between the X-ray source and the disc decreases as the source softens. However, near transition this evolution breaks, showing a sudden increase (decrease) in lag amplitude (frequency). On the other hand, the temperature of the quasi-thermal component in covariance spectra, due to disc irradiation and responsible for the observed soft reverberation lags, consistently increases throughout all the analysed observations.

Conclusions. This study proposes an alternative interpretation to the recently proposed contracting corona scenario. Assuming a constant height for the X-ray source, the steady increase in the reverberation lag frequency and in the irradiated disc temperature in high-frequency covariance spectra can be explained in terms of a decrease in the disc inner radius as the source softens. The behaviour of thermal reverberation lags near transition might be related to the relativistic plasma ejections detected at radio wavelengths, suggesting a causal connection between the two phenomena. Throughout most of the hard and hard-intermediate state, the disc is consistent with being truncated (with an inner radius Rin ≳ 10 Rg), reaching close to the innermost stable circular orbit only near transition.
Spectroscopic observations of PHz G237.01+42.50: A galaxy protocluster at z = 2.16 in the Cosmos field
Authors: Polletta M. , Soucail G. , Dole H. , Lehnert M. D. , Pointecouteau E. , Vietri G. , Scodeggio M. , Montier L. , Koyama Y. , Lagache G. , Frye B. L. , Cusano F. , Fumana M.
Published: August 2021

The Planck satellite has identified more than 2000 protocluster candidates with extreme star formation rates (SFRs). Here, we present the spectroscopic identification of a Planck-selected protocluster located in the Cosmos field, PHz G237.01+42.50. PHz G237.01+42.50 contains a galaxy overdensity of 31 spectroscopically identified galaxies at z ≃ 2.16 (significant at 5.4σ) in a 10′ × 11′ region. The overdensity contains two substructures or protoclusters at ⟨z⟩ ≃ 2.16 and 2.195 with estimated halo masses at z = 0 of ∼5–6 × 1014 M⊙, roughly consistent with Virgo-type clusters. The overdensity total SFR, ∼4000 M⊙ yr−1, is higher than predicted by simulations but much smaller than the SFR derived from the Planck data (i.e., 10 173 M⊙ yr−1). The analysis of the Herschel data in the field, in combination with the available ancillary data, shows that such a difference is due to an effect of source alignment along the line of sight that produces a 5σ overdensity of red Herschel sources in the field. We analyze the members’ ultraviolet (UV) spectra and UV-far-infrared spectral energy distributions to derive their SFR, stellar mass, and metallicity. Galaxy members include blue star-forming galaxies and Active galactic nuclei (AGN) with SFRs and stellar masses consistent with the main sequence. Active galactic nuclei, identified through optical spectroscopy or X-ray data, represent a significant fraction (20 ± 10%) of all members of the protocluster at z = 2.16, and they are powerful enough to produce radiative feedback. The core of this protocluster, besides being denser, includes members that are, on average, more massive and star-forming and contains a larger fraction of AGN and Herschel-detected galaxies than the full sample, suggesting an environmental effect on galaxy growth. A comparison between PHz G237.01+42.50 and other protoclusters in the literature at similar redshifts reveals some common traits and differences that reflect both observational biases and a diversity in intrinsic properties that is not yet fully understood.
V-band photometry of asteroids from ASAS-SN
Authors: Hanuš J. , Pejcha O. , Shappee B. J. , Kochanek C. S. , Stanek K. Z. , Holoien T. W.-S.
Published: August 2021

We present V-band photometry of the 20 000 brightest asteroids using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) between 2012 and 2018. We were able to apply the convex inversion method to more than 5000 asteroids with more than 60 good measurements in order to derive their sidereal rotation periods, spin axis orientations, and shape models. We derive unique spin state and shape solutions for 760 asteroids, including 163 new determinations. This corresponds to a success rate of about 15%, which is significantly higher than the success rate previously achieved using photometry from surveys. We derive the first sidereal rotation periods for additional 69 asteroids. We find good agreement in spin periods and pole orientations for objects with prior solutions. We obtain a statistical sample of asteroid physical properties that is sufficient for the detection of several previously known trends, such as the underrepresentation of slow rotators in current databases, and the anisotropic distribution of spin orientations driven by the nongravitational forces. We also investigate the dependence of spin orientations on the rotation period. Since 2018, ASAS-SN has been observing the sky with higher cadence and a deeper limiting magnitude, which will lead to many more new solutions in just a few years.
A fuzzy DEMATEL approach for evaluating the risk factors
Authors: Fakhrzad Mohammad-Bagher , Firozpour Mohammad-Reza , Hosseini Nasab Hasan
Published: August 2021

Many risk factors are dependent on each other and taking this into account can be helpful in managing appropriate decisions. The poor evaluation of these factors will impose high costs in many real applications especially for a supply chain. There are different methods for risk evaluating and their effects for ranking them. For instant, in fuzzy DEMATEL method, the experts’ linguistic opinions and preferences on the agent effects are used as the input. The important point is how these opinions are aggregated to produce less computational error. In this regard, this paper proposes a new method based on statistical inferences for a fuzzy DEMATEL approach for evaluating the factors of a supply chain. This method was applied to a case study and the results showed that the proposed method was better than other methods for integrating the experts’ opinions in a supply chain. However, this method was proposed for the evaluation of supply chain factors, it can be applied to other systems as well.
Intraarterial Chemotherapy for Retinoblastoma – Initial Experiences of a German Reference Centre
Authors: Kiefer Tobias , Schlüter Sabrina , Bechrakis Nikolaos E. , Bornfeld Norbert , Göricke Sophia , Ketteler Petra , Ting Saskia , Geismar Dirk , Biewald Eva
Published: August 2021

Background Adequate management of retinoblastoma requires a multidisciplinary and individual approach to treatment. Intraarterial chemotherapy (IAC) is one of the most commonly used treatment modalities, and enables supraselective application of chemotherapy via the ophthalmic artery and is now established in almost all treatment centres. However, published treatment success rates are heterogeneous. There are some unanswered issues regarding sight-threatening ocular complications and the long-term occurrence of secondary malignancies and metastatic disease. The objective of the present study is to analyse the results of a German national reference centre.

Methods Retrospective analysis of all children with an indication for at least one IAC from April 2010 to April 2020. IAC was used either as primary or recurrence therapy. Obligatory follow-up was at least 6 months.

Results 137 eyes of 127 children with an indication for IAC could be included. 12 eyes with a follow-up of less than 6 months and 37 eyes in which IAC was technically not feasible were excluded. In summary, 88 eyes of 79 children were finally analysed. Mean follow-up was 38 months, ranging from 7 to 117 months. In total, 195 procedures were completed. In 30 eyes (34.1%) IAC was conducted as primary and in 58 (65.9%) as secondary therapy. There was an initial IAC treatment response in 75 eyes (85.2%) with a recurrence-free rate of 61.3%. Eye salvage rate was 68.1% with 28 enucleated eyes in total. Ocular complications were observed in 36 eyes (40.9%), with 19 eyes (21.6%) showing severe sight-threatening and 11 eyes (12.5%) presenting minor non-sight-threatening toxic reactions. During follow-up, 1 child developed a secondary malignancy, 1 child developed metastasis and 1 child died as a consequence of trilateral retinoblastoma.

Conclusion In summary, IAC is a potent modality for retinoblastoma treatment and has been very successful, even in advanced disease and heavily pretreated eyes. However, ocular complications should be taken in consideration, especially when the only seeing eye is treated. Long term incidences of secondary malignancies and metastatic diseases should be further investigated in prospective studies.
Injury Profile among Elite Youth Male Football Players in a German Academy
Authors: Jaber Ayham , Weishorn Johannes , Berrsche Gregor , Ott Henning , Bangert Yannic
Published: August 2021

Studies that report injuries in elite youth football players are scarce. So far, no such studies have been reported in Germany. The aim of this study is to descriptively and statistically report the incidence of injuries that resulted in time-loss ≥ 4 days in the TSG Hoffenheim football academy by 138 male players aged between 12 and 19 years during one season. A total of 109 injuries were sustained by 76 players: 6.9 injuries occurred per 1000 hours of matches (95% CI, 5.0–9.6) and 0.7 injuries per 1000 hours of training (95% CI, 0.5–0.9) with a ratio of 9.8. Some 66% of all injuries occurred during matches. Injuries involved the lower limb (81%), upper limb (9%), head & neck (5%) and trunk injuries (5%). 21 (19%) of all injuries were regarded as severe and resulted in time-loss > 28 days. U16–U19 teams sustained more injuries (74, 68%) than U12–U15 (35, 32%) (P= 0.032). The most frequent diagnosis was thigh strain (22%). Time-loss ranged from 4–339 days (SD: 40, Average: 23). Many injuries were a result of strain. Available injury prevention programs should be adhered to more strictly. Dedicated epidemiological studies are needed to optimize focused injury prevention programs.
Uveal Melanoma – Standardised Procedure in Diagnosis, Therapy and Surveillance
Authors: Bechrakis Nikolaos E. , Bornfeld Norbert , Heindl Ludwig M. , Skoetz Nicole , Leyvraz Serge , Joussen Antonia M.
Published: August 2021

Background Uveal melanoma is a rare intraocular tumour, for which there is currently no national evidence-based guideline in Germany. The aim of this project was to provide a common standard operating procedure (SOP) for the diagnosis, treatment and follow-up care of uveal melanoma, within the network of German leading oncology centres funded by German Cancer Aid. The SOP was created as part of a moderated consensus process.

Results and Conclusion In a multistage process, a common SOP was developed for the diagnosis, therapy and follow-up of uveal melanoma, as based on current knowledge of the subject.
High Chemoselectivity in the Construction of Aryl Methyl Sulfones via an Unexpected C–S Bond Formation between Sulfonylhydrazides and Dimethyl Phosphite
Authors: Huang Chao , Cheng Feixiang , Liu Teng , Yu Shiwen , Shen Xiang , Li Yixian , Liu Jianjun
Published: August 2021

A highly chemoselective route to aryl methyl sulfones via an unexpected C–S bond formation between sulfonylhydrazides and dimethyl phosphite catalyzed by NaI under mild conditions has been established. This transformation provides an alternative and metal-free pathway to acquire various aryl methyl sulfones in good to excellent yields. Notably, dimethyl phosphite was employed as a stable and readily available alkyl source.
Diagnosis and Neurosurgical Management of Cerebral Nocardiosis
Authors: Karam Carley , Siadati Abdolreza
Published: August 2021

Primary Nocardia infections are uncommon gram-positive bacterial infections caused by aerobic actinomycetes and are typically regarded as opportunistic infections (only one-third of infected patients are immunocompetent). Risk factors include: glucocorticoid therapy, malignancy, organ transplant recipients, human immunodeficiency virus infections, tumor necrosis factor-α inhibitor therapy, diabetes mellitus, alcoholism, inflammatory bowel disease, chronic obstructive pulmonary disease, chronic granulomatous disease, and tuberculosis. The organism has a predisposition to disseminate to the central nervous system and can relapse or progress despite appropriate therapy. Treatment ranges from oral antibiotic management to multiple intravenous antibiotic therapy, with surgical intervention required for severe cases. The surgical options include aspiration or complete excision of abscess contents and capsule. In the present case, we describe the use of bilateral craniotomy with assisted image guidance and multiple abscess excision in an immunocompetent patient with systemic nocardiosis.
Prediction of Major Bleeding in Anticoagulated Patients for Venous Thromboembolism: Comparison of the RIETE and the VTE-BLEED Scores
Authors: Lecumberri Ramón , Jiménez Laura , Ruiz-Artacho Pedro , Nieto José Antonio , Ruiz-Giménez Nuria , Visonà Adriana , Skride Andris , Moustafa Fares , Trujillo Javier , Monreal Manuel ,   for the RIETE investigators
Published: August 2021

The performance of validated bleeding risk scores in patients with venous thromboembolism (VTE) could be different depending on the time after index event or the site of bleeding. In this study we compared the “classic” Registro Informatizado de Enfermedad TromboEmbólica (RIETE) score and the more recently developed VTE-BLEED score for the prediction of major bleeding in patients under anticoagulant therapy in different time intervals after VTE diagnosis. Out of 82,239 patients with acute VTE, the proportion of high-risk patients according to the RIETE and VTE-BLEED scores was 7.1 and 62.3%, respectively. The performance of both scores across the different study periods (first 30 days after VTE diagnosis, days 31–90, days 91–180, and days 181–360) was similar, with areas under the receiving operating characteristics (ROC) curve (AUC) ranging between 0.69 and 0.72. However, the positive predictive values were low, ranging between 0.6 and 3.9 (better for early major bleeding than for later periods). A sensitivity analysis limited to patients with unprovoked VTE showed comparable results. Both scores showed a trend toward a better prediction of extracranial than intracranial major bleeding, the RIETE score resulting more useful for early extracranial bleeding and the VTE-BLEED for late intracranial hemorrhages. Our study reveals that the usefulness of available bleeding scores may vary depending on the characteristics of the patient population and the time frame evaluated. Dynamic scores could be more useful for this purpose.
Biliary Strictures: A Surgeon's Perspective for Interventional Radiologists
Authors: Katariya Nitin , Mathur Amit K.
Published: August 2021

Biliary strictures can be a challenging clinical problem to manage and often have unclear etiologies, including benign and malignant causes. Left untreated, these problems can lead to significant morbidity and mortality linked to their underlying diagnosis. The approach to adult patients with biliary strictures requires a multidisciplinary team involving surgeons, interventional endoscopists, and interventional radiologists for diagnosis, symptom relief, palliation, as well as potential curative management. From a surgeon's perspective, there are many ways to classify and approach these strictures. It is of paramount importance to start with an excellent understanding of the patient's prior surgical history. In approaching a patient with a new diagnosis of biliary stricture, it is also critical to understand its etiology relatively quickly, as 70% are malignant in the adult population. Concurrently, one must clearly define the location and extent of the stricture: intrahepatic, hilar, or distal extrahepatic bile duct, as well as whether it is a singular lesion or multifocal phenotypes. This information provides a path forward in clinical decision-making regarding durability and efficacy of therapy, which is typically aimed at decompression and/or surgical resection to prevent cholangitis, sepsis, and progressive hepatic insufficiency.
Treatment of Malignant Bile Duct Obstruction: What the Interventional Radiologist Needs to Know
Authors: Camacho Juan C. , Brody Lynn A. , Covey Anne M.
Published: August 2021

Management of malignant bile duct obstruction is both a clinically important and technically challenging aspect of caring for patients with advanced malignancy. Bile duct obstruction can be caused by extrinsic compression, intrinsic tumor/stone/debris, or by biliary ischemia, inflammation, and sclerosis. Common indications for biliary intervention include lowering the serum bilirubin level for chemotherapy, ameliorating pruritus, treating cholangitis or bile leak, and providing access for bile duct biopsy or other adjuvant therapies. In some institutions, biliary drainage may also be considered prior to hepatic or pancreatic resection. Prior to undertaking biliary intervention, it is essential to have high-quality cross-sectional imaging to determine the level of obstruction, the presence of filling defects or atrophy, and status of the portal vein. High bile duct obstruction, which we consider to be obstruction above, at, or just below the confluence (Bismuth classifications IV, III, II, and some I), is optimally managed percutaneously rather than endoscopically because interventional radiologists can target specific ducts for drainage and can typically avoid introducing enteric contents into isolated undrained bile ducts. Options for biliary drainage include external or internal/external catheters and stents. In the setting of high obstruction, placement of a catheter or stent above the ampulla, preserving the function of the sphincter of Oddi, may lower the risk of future cholangitis by preventing enteric contamination of the biliary tree. Placement of a primary suprapapillary stent without a catheter, when possible, is the procedure most likely to keep the biliary tree sterile.
Role of Interventional Radiology in the Management of Acute Cholangitis
Authors: Entezari Pouya , Aguiar Jonathan A. , Salem Riad , Riaz Ahsun
Published: August 2021

Acute cholangitis presents with a wide severity spectrum and can rapidly deteriorate from local infection to multiorgan failure and fatal sepsis. The pathophysiology, diagnosis, and general management principles will be discussed in this review article. The focus of this article will be on the role of biliary drainage performed by interventional radiology to manage acute cholangitis. There are specific scenarios where percutaneous drainage should be preferred over endoscopic drainage. Percutaneous transhepatic and transjejunal biliary drainage are both options available to interventional radiology. Additionally, interventional radiology is now able to manage these patients beyond providing acute biliary drainage including cholangioplasty, stenting, and percutaneous cholangioscopy/biopsy.
Elevated ESR and CRP Prior to Second-Stage Reimplantation Knee Revision Surgery for Periprosthetic Joint Infection Are Associated with Increased Reinfection Rates
Authors: Klemt Christian , Padmanabha Anand , Esposito John G. , Laurencin Samuel , Smith Evan J. , Kwon Young-Min
Published: August 2021

Although two-stage revision surgery is considered as the most effective treatment for managing chronic periprosthetic joint infection (PJI), there is no current consensus on the predictors of optimal timing to second-stage reimplantation. This study aimed to compare clinical outcomes between patients with elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior to second-stage reimplantation and those with normalized ESR and CRP prior to second-stage reimplantation. We retrospectively reviewed 198 patients treated with two-stage revision total knee arthroplasty for chronic PJI. Cohorts included patients with: (1) normal level of serum ESR and CRP (n = 96) and (2) elevated level of serum ESR and CRP prior to second-stage reimplantation (n = 102). Outcomes including reinfection rates and readmission rates were compared between both cohorts. At a mean follow-up of 4.4 years (2.8–6.5 years), the elevated ESR and CRP cohort demonstrated significantly higher reinfection rates compared with patients with normalized ESR and CRP prior to second-stage reimplantation (33.3% vs. 14.5%, p < 0.01). Patients with both elevated ESR and CRP demonstrated significantly higher reinfection rates, when compared with patients with elevated ESR and normalized CRP (33.3% vs. 27.6%, p = 0.02) as well as normalized ESR and elevated CRP (33.3% vs. 26.3%, p < 0.01). This study demonstrates that elevated serum ESR and/or CRP levels prior to reimplantation in two-stage knee revision surgery for chronic PJI are associated with increased reinfection rate after surgery. Elevation of both ESR and CRP were associated with a higher risk of reinfection compared with elevation of either ESR or CRP, suggesting the potential benefits of normalizing ESR and CRP prior to reimplantation in treatment of chronic PJI.
Increasing prediction accuracy of plasma arc properties by considering current density deduced from measured cathode region
Authors: Tang Hao , Liu ZuMing
Published: August 2021

To accurately simulate the plasma arc (PA) behavior in a wide current range, a steady two-dimensional model for the numerical calculation of the axisymmetric PA considering the high temperature cathode region (HTCR) was proposed. Based on the experimentally measured HTCR area, two distribution forms, namely, the mean value method and the Gaussian distribution method, were used to simulate the current density distribution behavior in the tungsten tip. The two proposed current densities were compared with the average current density model with a fixed discharge region. The Gaussian distribution form was chosen after a comprehensive comparison of experimental measured data and simulation data in aspects of arc pressure, electron temperature, and arc voltage at a welding current of 120 A. The model was verified to be accepted in a current range of 110–170 A by comparing the simulated and measured peak arc pressure values. The model has higher prediction accuracy over the common plasma arc model with the unchanged tip cathode, extends the prediction current range, and provides a tool for optimizing the nozzle structure and process parameters.
Defect-correlated skyrmions and controllable generation in perpendicularly magnetized CoFeB ultrathin films
Authors: Yin Haihong , Zheng Xiangyu , Wang Junlin , Zhou Yu , Kuerbanjiang Balati , Li Guanqi , Lu Xianyang , Tong Kaiyu , Wang Yichuan , Wu Jing , Lazarov Vlado K. , Evans Richard F. L. , Chantrell Roy W. , Cai Jianwang , Liu Bo , Meng Hao , Xu Yongbing
Published: August 2021

Skyrmions have attracted significant interest due to their topological spin structures and fascinating physical features. The skyrmion phase arises in materials with a Dzyaloshinskii–Moriya interaction at interfaces or in volume of non-centrosymmetric materials. Although skyrmions have been demonstrated experimentally, the general critical intrinsic relationship among fabrication, microstructures, magnetization, and the existence of skyrmions remains to be established. Here, two series of CoFeB ultrathin films with controlled atomic scale structures are employed to reveal this relationship. The amount of defects was artificially tuned by inverting the growth order, and skyrmions were shown to be preferentially formed in samples with more defects. By utilizing first-order reversal curves, the stable region and the skyrmion densities can be efficiently controlled in the return magnetization loops. These findings establish a general internal link from sample preparation to skyrmion generation and provide a general method for controlling skyrmion density.
From atomistic tight-binding theory to macroscale drift–diffusion: Multiscale modeling and numerical simulation of uni-polar charge transport in (In,Ga)N devices with random fluctuations
Authors: O’Donovan Michael , Chaudhuri Debapriya , Streckenbach Timo , Farrell Patricio , Schulz Stefan , Koprucki Thomas
Published: August 2021

Random alloy fluctuations significantly affect the electronic, optical, and transport properties of (In,Ga)N-based optoelectronic devices. Transport calculations accounting for alloy fluctuations currently use a combination of modified continuum-based models, which neglect to a large extent atomistic effects. In this work, we present a model that bridges the gap between atomistic theory and macroscopic transport models. To do so, we combine atomistic tight-binding theory and continuum-based drift–diffusion solvers, where quantum corrections are included via the localization landscape method. We outline the ingredients of this framework in detail and present first results for uni-polar electron transport in single and multi- (In,Ga)N quantum well systems. Overall, our results reveal that both random alloy fluctuations and quantum corrections significantly affect the current–voltage characteristics of uni-polar electron transport in such devices. However, our investigations indicate that the importance of quantum corrections and random alloy fluctuations can be different for single and multi-quantum well systems.
Analysis of vortices in viscoelastic fluid flow through confined geometries at low Reynolds numbers
Authors: Zargartalebi Ali , Zargartalebi Mohammad , Benneker Anne M.
Published: August 2021

Understanding the behavior of viscoelastic (VE) fluids in confined geometries is crucial for applications in biologic systems, heat transfer devices, enhanced oil recovery, and many others. Here, we perform a systematic steady-state simulation of a VE fluid at low Reynolds numbers through a channel with successive smooth contractions and expansions. We analyze the hydrodynamic performance of the fluid with particular attention to vortex patterns that develop downstream of the contractions. We show that elastic vortices form at higher contraction ratios and that there are critical Weissenberg numbers (Wic) unique to each contraction ratio where the flow shifts from non-vortical to vortical. This Wic increases with an increasing contraction length. The coexistence of elongational-, shear-, and rotational-flow is essential for vortex development and evolution. We also analyzed the effect of the Deborah number (De) on the vortex pattern in a multiple contraction system and observed that the vortex area significantly depends on the distance between the contractions. We show that there are three distinctly different regions in De, in which the flow characteristics change in successive contractions. For high De, the flow in the downstream contraction is significantly affected by the upstream contraction. Our results have implications for the use of VE fluids with various VE properties in different types of porous media.
Self-propulsion dynamics of small droplets on general surfaces with curvature gradient
Authors: Chen Yujuan , Xu Xianmin
Published: August 2021

We study theoretically the self-propulsion dynamics of a small droplet on general curved surfaces by a variational approach. A new reduced model is derived based on careful computations for the capillary energy and the viscous dissipation in the system. The model describes quantitatively the spontaneous motion of a liquid droplet on general surfaces. In particular, it recovers previous models for droplet motion on the outside surface of a cone. In this case, we derive a scaling law of the displacement s∼t1/3 of a droplet with respect to time t by asymptotic analysis. Theoretical results are in good agreement with experiments in previous literature without adjusting the friction coefficient in the model.
EURAMET comparison of 500 kg mass standard EURAMET.M.M-S7
Authors: Grum M , Zůda J , Grgić G , Nawotka M , Žandarova T , Pärn A , Kilponen S , Gutfelt B , Neuvonen P T , Zelenka Z , Wüthrich C , Panesar M , Conceição P , Pirée H , Vámossy C , Ališić Š , Vukoslavović G , Pantić D , Mangutova-Stoilkovska B , Miteva M , Popa G F
Published: August 2021

Main text

In order to demonstrate the equivalence in calibration of 500 kg mass standard, a supplementary comparison has been carried out by 20 members of EURAMET. The overall result shows a good consistency among the participants.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Inverse Domination To The Transformation Of Path Related Graphs
Authors: Santha S. , Krishna Veni G.T.
Published: August 2021

A set D of vertices in a graph G (V, E) is a dominating set of G, if every vertex in V-D is adjacent to at least one vertex in D. If V-D contains a dominatingset D’ of
G then D’ is called an inverse dominating set with respect to
D. In this paper we have established some theorems and properties of the inverse domination number to the transformation of path related graphs.
Total Energy of Cycle and Some Cycle Related Graphs
Authors: Palani K. , LalithaKumari M. , Pandiselvi L.
Published: August 2021

In this article we write algorithms and MATLAB programs to find the total energy of Cycle and some Cycle related graphs. The concept of total matrix and total energy of a graph G is introduced by K.Palani&M.Lalithakumari in [9]. Let G=(V, E) be a (p, q) simple graph. Let V (G) = {ν

i
/i = 1,2, … p} and E (G) = {e

i
/i = 1,2, … q}. The total matrix T = T(G) of G is a square matrix of order p + q whose (i, j)-entry is defined as:

T
=

(

t

i
j

)

=

{

1

if

v

i

adjacent to

v

j

i
≠
j

1

if

e

i

adjacent to

e

j

i
≠
j

1

e

i

incident with

v

j

0

otherwise

The Total Energy of a graph is the sum of absolute value of the eigen values of its Total matrix T(G). For any (p, q) graph G, the total number of eigen value is p+q.

Let λ
1, λ
2, λ
3, … λ

p+q
be the eigen values of T. Then total energy of G is T
E =

∑

i
+
1

p
+
q

|

λ

i

|

.
Structure and phase composition features of nickel-based superalloy after electron beam additive process
Authors: Gurianov D A , Fortuna S V , Nikonov S Y , Kulkov S N
Published: August 2021

In the present work, the structure and properties of products from heat-resistant nickel-based superalloy ZhS6U formed by wire-feed electron beam additive technology were investigated. Products were obtained under different parameters of electron beam additive process (accelerating voltage, beam current and movement speed of working table were varied). It was shown that a high speed of displacement leads to the formation of defects in the form of cracks and delamination of the obtained product from the substrate, which also leads to the appearance of cracks. It has been established that the greatest energy input leads to evaporation of aluminum (the main hardening γ’ phase). The phase composition of the additive product did not differ from the original material.
Investigation of plasmachemical synthesis of oxide compositions for plutonium-thorium dispersion nuclear fuel
Authors: Karengin A G , Karengin A A , Novoselov I Yu , Tikhonov A E
Published: August 2021

This paper presents the results of experimental studies on the process of plasmachemical synthesis of fuel oxide compositions for plutonium-thorium dispersion nuclear fuel. Precursors were simulated water-organic nitrate solutions, which have a lower calorific value near 8.4 MJ/kg. The precursors consisted of an organic component (acetone) and mixed water nitrate solutions including a matrix metal (magnesium, yttrium), samarium (instead of plutonium), and cerium (instead of thorium). The authors determined the compositions and modes of processing simulated solutions that provide plasmachemical synthesis of nanosized complex oxide powders imitating plutonium-thorium dispersion nuclear fuel.
Spark plasma sintering of transparent YAG:Ce ceramics with LiF flux
Authors: Paygin V D , Ilela A E , Deulina D E , Lyamina G V , Stepanov S A , Alishin T R , Dvilis E S , Khasanov O L , Valiev D T , Kalashnikov M P
Published: August 2021

Transparent yttrium aluminum garnet (YAG) ceramics doped with cerium ions (Ce3+) were successfully synthesized using the spark plasma sintering (SPS) process at a temperature of 1600 °C, isothermal exposure 10 minutes, pressure 100 MPa and a heating rate 10 °C/min from a mechanical mixture of powders of yttrium, aluminum, and cerium oxides. Transmittance in the visible range for 1 mm thick samples is above 40 %; in the near infrared is above the 60 %. Vickers hardness was 15±1.05 GPa. The optimal SPS conditions have been discussed and suggested in order to obtain a good combination of density and transmittance.
Study of thermophysical characteristics of composite sorption-active materials for life support systems of manned spacecraft and civil aviation
Authors: Ferapontova L L , Zakharov I V , Ferapontov Y A , Kurzina I A , Grunski V N
Published: August 2021

The method of differential thermal analysis (DTA) was used to study the heat resistance of composite sorption-active materials (CSAM) based on a matrix of fluoroplast and NaX crystallites. Decrease in the temperature of thermal destruction of the polymer matrix by about 90°C was found with an increase in the NaX content in KCAM from 2 to 25% by weight. Using the original method, the thermal conductivity was also studied. The analysis of the totality of the obtained results suggests that the studied parameters depend on the ratio of adsorbent-filler/polymer matrix: with an increase in the binder content in the CSAM from 5 to 25 wt. % thermal conductivity decreases from 0.227 to 0.184 W/mk. This pattern is due to the growth of CSAM mesopores filled with air. The hypothesis is confirmed by the analysis of the secondary porous structure of KSAM
Elemental composition of single-phase kidney stones. Part II
Authors: Aleksandrova A , Tsygankova A , Lundovskaya O , Korolkov I , Filatov E , Sabantseva E , Gubanov A
Published: August 2021

The article is devoted to the element composition study of 5 kidney stones types. Calculi consisting of calcium oxalate, uric acid, hydroxyapatite, brushite and struvite were analysed by optical emission spectrometry with inductively coupled plasma (ICP-OES). The elements Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Na, P, Sr and Zn were determined in each stone types. Also, correlation analysis for stones consisting of uric acid (n=100) was performed and Spearman’s rank correlation coefficient was calculated. Average and high positive correlations were found between K/Mg, Mg/Na, Mg/P, Mg/Sr, Na/P (r=0.41 ÷ 0.50) and Ca/Sr (r=0.71) respectively.
Assessing the efficiency of using carbon nanocomposite materials for corrosion protection of gas pipelines
Authors: Belov D , Gruchenkova A , Chepur P
Published: August 2021

The use of innovative technologies in the transportation and production of hydrocarbons is one of priority tasks. In the context of competition for energy, this issue is brought to the fore in the development of areas for the modernization of the industry. In addition, it is a matter of strengthening the country’s competitive advantage in the world market of fuel and energy carriers. The study is dedicated to finding ways to improve the composition of anticorrosive coatings used in the gas industry. The paper studies the physical and mechanical characteristics of the main anticorrosive coatings. Carbon nanotubes were found to be the most profitable and economically viable. The composite material with new nanotubes was studied by comparing the physical and mechanical properties of various anticorrosive coatings in the framework of the experiment. The results of the experiment confirmed the feasibility of using nanotechnological materials and coatings. So, the use of carbon nanocomposites in the composition of anticorrosive coatings will increase the efficiency of transportation of gas, oil, and other raw materials.
Research of light diffraction on multilayer inhomogeneous holographic PPM diffraction structures formed under PIA conditions
Authors: Dolgirev V O , Sharangovich S N
Published: August 2021

This work presents a research of the diffraction of light on the multilayer inhomogeneous holographic diffraction structures (MIHDS) in a photopolymer material (PPM) under photoinduced light absorption (PIA) conditions. Considering PIA, the authors showed possible distortions of the selective response of the diffracted beam due to the heterogeneity of the profiles of lattices over the depth of the layer.
Rapid direct electric heating of fresh concrete
Authors: Batyuk M I , Gnyrya A I , Ushakov V Ya , Korobkov S V
Published: August 2021

Direct electric curing as a volume-heating method can provide fairly uniform temperature field at high heating rates. However, most of the current research focuses on reproduction of general form of temperature curve used in conventional techniques, i.e. at low heating rates. This paper evaluates the effect of rapid direct electric heating of fresh concrete on temperature variation, compressive strength and energy consumption. Samples subjected to rapid electric heating to 50, 60 and 70°C in 10 minutes were insulated, kept for 13 hours, demolded and tested for compressive strength. According to measurements in three points saved every 30 seconds, the temperature field remains uniformly over the cycle. The ratio of energy consumption and the resulting strength allows to select the most optimal mode for a particular case. It has been determined that an increase in temperature of 10 °C leads to an increase in strength by 4% (for the considered composition). Results derived from this study confirm the effectiveness of applying rapid electric heating of fresh concrete for precast concrete production.
Forecast of the near ground air temperature based on the multilayer perceptron model
Authors: Del I V , Starchenko A V
Published: August 2021

In this study, a multilayer perceptron model is implemented for predicting meteorological values. Based on the known distribution of meteorological values for several previous days, the task was set to predict the values of the near ground air temperature. The overall mean square error for the entire forecast was 3.11 C. Comparison of various optimization methods showed the advantage of the method of Adaptive Moment Estimation. Comparison of the multilayer perceptron model forecasting results with the Weather Research and Forecasting numerical model forecast showed the promise of using neural networks to predict meteorological parameters at weather observation points.
Application of a Weather Research and Forecasting model to study the urban heat island in Tomsk
Authors: Svarovsky A I , Starchenko A V
Published: August 2021

The results of application of a Weather Research and Forecasting model (version 4.2) to study the heat island phenomenon in the city of Tomsk are considered. The results of numerical calculations were compared with measurements obtained using the instruments of Joint Use Center (JUC) Atmosphere and Tomsk Bogashevo Airport. On some days, the temperature difference between the city and the suburbs was shown to reach 1-3 °C.
Transition metals in the process of complexation with organic ligands containing heteroatoms in the structure
Authors: Marakina E I , Andrienko O S , Sachkov V I , Medvedev R , Amelichkin I , Shcherbakov P S
Published: August 2021

The synthesis and research of copper subgroup metal complexes with organic ligands, which have several heteroatoms in their structure, is highly perceptive. Since the resulting complex compounds differ in physical and chemical properties from the original organic compounds they will have a set of new characteristics of practical significance. In this study, 2-mercaptonicotinic acid and 2-mercapto-4(3H)-quinazolinone were used. During the research, complex compounds of metals of the copper subgroup were obtained from aqueous and water-alcohol solutions. The resulting compounds represent colored powder-like materials. The coordination of the organic reagent to metal ions was established by instrumental methods of analysis. The effect of the introduced reagent (alkali, ammonia) on the coordination of the organic reagent was investigated.
Friction Stir Processing of Aluminum Alloy 5556 With Different Pin Configuration of Tool
Authors: Sudarikov A V , Chumaevskii A V , Dobrovolsky A R , Zykova A P , Gusarova A V , Gurianov D A , Ivanov A N
Published: August 2021

The paper investigates the features of the friction stir processing of aluminum-magnesium alloy using tools with a screw pin and with a square section pin. The conducted studies show that during the friction stir process with a tool with a square cross-section pins it is possible to form instabilities during treatment, leading to non-uniform longitudinal movement of the tool and formation of defects. One mechanism for this phenomenon could be contamination of the surface of the aluminum-magnesium alloy treating tool after working on aluminum-silicon alloys, resulting in unstable adhesion contact. This effect is less noticeable for treating by tool with a cylindrical pin. Mechanical properties of the treated material in 1-4 passes remain quite close and the average ultimate tensile strength of the stir zone is 325-335 MPa. The plasticity of the material decreases on average from 33% to 25-30%, but remains at an acceptable level. The average ultimate tensile strength and ductility values are slightly higher when processing with a square-shaped pin tool than when processing with a spiral-shaped pin tool.
Friction Stir Processing Regularities of Cast Aluminum Alloy AlSi12
Authors: Indoitu D V , Gusarova A V , Zykova A P , Kalashnikova T A , Chumaevskii A V , Gurianov D A , Beloborodov V A
Published: August 2021

The paper studies the structure and morphology of the treating zone surface of cast aluminum alloy AlSi12 after 1-4 passes with a friction stir tool. The studies show that after all four passes, the surface of the tool exit zone has traces of material tearing out along the edge of the pin, but the overall appearance of the machining surface improves. The structure after four passes with the tool is dominated by smaller and more rounded particles, while after one pass there is a large number of elongated particles. Friction stir processing leads to improvement of material plasticity by up to 2.5 times and ultimate tensile strength value by 9-10%.
Clustering-based rule generation methods for fuzzy classifier using Autonomous Data Partitioning algorithm
Authors: Svetlakov M O , Hodashinsky I A
Published: August 2021

In this paper, clustering-based rule generation methods for fuzzy classifier using non-parametric Autonomous Data Partitioning algorithm have been proposed. ADP-algorithm is used to determine the number of clusters for use in various k-means-like clustering algorithms. Proposed method contributes to solving the problem of determining optimal number of clusters/rules. The efficiency of fuzzy classifiers with rules constructed by the specified algorithms has been tested on data sets from the KEEL repository. Experimental results show that proposed method outperforms baseline algorithm (the extremums rulebase generation algorithm) both in terms of classification accuracy and geometric mean metrics.
Sub-THz absorbers based on BaTiO3/Epoxy composites
Authors: Moskalenko V D , Shematilo T N , Dorozhkin K V , Badin A V
Published: August 2021

The paper presents the results of studying electromagnetic response from polymer composite materials in the frequency range from 0.1 THz to 1.6 THz obtained using a BWO-based spectrometer and a time-domain spectrometer. The composites used were epoxy resin with the addition of barium titanate (BaTiO3) with a mass concentration of 40% to 80%. Based on these data, the values of the complex permittivity of composite samples are calculated and analyzed, and the electromagnetic response from the samples is modeled. An assessment of the applicability of this material in the elements of the THz range technology is carried out.
Temperature distribution in the phantom of limb in the microwave chamber with linear source of radiation
Authors: Nechaev A N , Dunaevskii G E
Published: August 2021

The paper presents results of temperature distribution in the phantom of limb under the microwave radiation. The authors have developed automated apparatus based on linear positioner and temperature detector. The apparatus is aimed at measuring the distribution of thermal field in phantom of a human hand. It was shown that impulse microwave radiation with a power of 40W during 6 minutes leads to uniform heating along longitudinal axis of phantom. The apparatus “SMVi-200” was used as a microwave source being normally applied for hypothermia treatment.
Determination of mercury (II) by precipitation potentiometric titration
Authors: Zakharkiva A M , Shumar S V
Published: August 2021

The article presents the results of potentiometric titration of the solution containing Hg (II) with the solution of sodium diethylditheocarbamate (NaDEDC). The efficiency of electrochemical analysis is defined by the presence of the most appropriate indicator system. The possibility of using carbon composite electrode (CCE) as a sensor for mercury ions determination has been explored. The conditions for potentiometric determination of Hg (II) (titrant, indicating electrode, pH, response time, range of concentrations, and background electrolyte) were studied. Titration curves were processed by the linearization method.