bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of the hydrogen storage characteristics of MgH2 with a flake Ni nano-catalyst composite
Authors: Yang Xinglin , Hou Quanhui , Yu Libing , Zhang Jiaqi
Published: January 2021

The Mg2Ni/Mg2NiH4 formed in the original position in process of hydrogen absorption and dehydrogenation is distributed around Mg/MgH2, which accelerates the rate of hydrogen absorption and dehydrogenation.
Facilely controllable synthesis of copper-benzothiadiazole complexes via solvothermal reactions: exploring the customized synthetic approach by experiments
Authors: Hu Chen , Zhao Yingnan , Han Xiao , Song Jiaqi , Ding Jie , Hou Hongwei
Published: January 2021

In this work, five new copper-BTD complexes C1–C5 were obtained by delicately modulating the solvothermal conditions. Our experiments suggest that the fusion process of L1 is driven by a CuII/CuI catalytic cycle with DMSO acting as a co-oxidant.
Durable polymericN-halamine functionalized stainless steel surface for improved antibacterial and anti-biofilm activity
Authors: Rai Rajani Kant , Kanniyappan Hemalatha , Muthuvijayan Vignesh , Venkitasamy Kesavan , Jayakrishnan Athipettah
Published: January 2021

A stainless steel surface was functionalized with a novel hydantoin based copolymer and evaluated for antibacterial activity, anti-biofilm activity, and biocompatibility.
Magic-sized CdSe nanoclusters: a review on synthesis, properties and white light potential
Authors: Singh Vaibhav , Priyanka  , More Priyesh Vilas , Hemmer Eva , Mishra Yogendra Kumar , Khanna Pawan K.
Published: January 2021

Magic-sized CdSe nanoclusters have gained tremendous attention due to their white-light emitting properties and biological applications. The article discusses the challenges in synthesis to achieve their challenging optical properties.
Electrocatalytically inactive copper improves the water adsorption/dissociation on Ni3S2for accelerated alkaline and neutral hydrogen evolution
Authors: Zhang Lei , Gao Xiaorui , Zhu Ying , Liu Acan , Dong Huilong , Wu Dajun , Han Zhida , Wang Wei , Fang Yong , Zhang Jie , Kou Zongkui , Qian Bin , Wang Ting-Ting
Published: January 2021

Electrochemically inactive Cu was introduced into Ni3S2 nanoparticles to accelerate its Volmer step and strengthen water adsorption/dissociation on the respective Ni and S sites during the HER process, leading to superior HER performances.
Between plasmonics and surface-enhanced resonant Raman spectroscopy: toward single-molecule strong coupling at a hotspot
Authors: Itoh Tamitake , Yamamoto Yuko S.
Published: January 2021

The purpose of this minireview is to build a bridge between two research fields: surface-enhanced resonant Raman spectroscopy (SERRS) and the branch of plasmonics treating strong coupling between plasmons and molecular excitons.
Controllable synthesis of porous tubular carbon by a Ag+-ligand-assisted Stöber-silica/carbon assembly process
Authors: Shen Yang-Lin , Jin Jun-Ling , Chen Ning , Li Peng Ju , Xu Ting , Xie Yun-Peng , Lu Xing
Published: January 2021

Porous carbon tubes have been produced for the first timeviaa Stöber-silica/carbon co-assembly process upon dictation by Ag+and pyridyl-functionalized surfactants.
Custom plating of nanoscale semiconductor/catalyst junctions for photoelectrochemical water splitting
Authors: Oh Kiseok , de Sagazan Olivier , Léon Cyril , Le Gall Sylvain , Loget Gabriel
Published: January 2021

Templated nanoelectrodeposition on photoactive n-Si is introduced here for the customization of nanoscale inhomogeneous Schottky junctions. We demonstrate the use of these surfaces as photoanodes for water dissociation.
Structure-intensified PtCoRh spiral nanowires as highly active and durable electrocatalysts for methanol oxidation
Authors: Chen Xiaowei , Wang Wei , Chen Xuejiao , Liao Xinyan , Lyu Zixi , Liu Kai , Xie Shuifen
Published: January 2021

Ternary PtCoRh spiral nanowires with surface atomic steps and anti-corrosive Rh incorporation can serve as active and robust MOR electrocatalysts in acidic media.
Development and application of a high throughput assay system for the detection of Rieske dioxygenase activity
Authors: Preston-Herrera Cristina , Jackson Aaron S. , Bachmann Brian O. , Froese Jordan T.
Published: January 2021

A new periodate-based reactive assay system enables the rapid evaluation of thecis-dihydroxylation activity of Rieske dioxygenase enzymes.
Visible light-induced controlled surface grafting polymerization of hydroxyethyl methacrylate from isopropylthioxanthone semipinacol-terminated organic monolayers
Authors: Balasubramaniam Ajitha , Manderfeld Emily , Krause Lutz M. K. , Wanka Robin , Schwarze Jana , Beyer Cindy D. , Rosenhahn Axel
Published: January 2021

Reaction scheme of the visible light-induced controlled surface grafting polymerization of methacrylate monomers onto organosilane-coated silicon initiated by previously coupled dormant ITXSP groups.
EPR-derived structures of flavin radical and iron-sulfur clusters from Methylosinus sporium 5 reductase
Authors: Jeong Han Sol , Hong Sugyeong , Yoo Hee Seon , Kim Jin , Kim Yujeong , Yoon Chungwoon , Lee Seung Jae , Kim Sun Hee
Published: January 2021

The electronic structures of two cofactors, the FAD radical and [2Fe–2S]+ of reduced MMOR from Methylosinus sporium strain 5 were investigated by advanced EPR spectroscopy. The findings provide long overdue detailed structural information of MMOR.
A data-driven approach to generate pseudo-reaction sequences for the thermal conversion of Athabasca bitumen
Authors: Sivaramakrishnan Kaushik , Puliyanda Anjana , de Klerk Arno , Prasad Vinay
Published: January 2021

We use self-modeling multivariate curve resolution to identify pseudo-components and chemical transformations in thermal conversion of Athabasca bitumen.
Soft cavitation in colloidal droplets
Authors: Bruning Myrthe A. , Ohl Claus-Dieter , Marin Alvaro
Published: January 2021

When a pure droplet evaporates inside an elastic medium, two instabilities are typically observed: first creasing and then cavitation. Interestingly, particles stimulate cavitation to occur early, thereby even bypassing the creasing completely.
H4,4,4-graphyne with double Dirac points as high-efficiency bifunctional electrocatalysts for water splitting
Authors: Zhang Haona , Wei Wei , Wang Shuhua , Wang Hao , Huang Baibiao , Dai Ying
Published: January 2021

Porous H4,4,4-GY as a metal-free substrate for bifunctional SACs shows high-efficiency catalytic performance for water splitting.
Iron oxide encapsulated titanium niobate nanotubes as a high-performance lithium-free anode for solid-state batteries
Authors: Wu Wei , Lin Wang , Chen Hongjiang , Wei Keyan , Li Zhitong , Yang Haitao , Liu Mingxian , Xiang Huaicheng , Deng Libo , Yao Lei
Published: January 2021

In the core–shell α-Fe2O3@TiNb2O7 nanofiber, the high rate character of TNO and high capacity of α-Fe2O3 work synergistically to provide enhanced specific capacity with prolonged cycle life and good rate capability, as a high performance Li-free solid-state battery anode.
All annealing-free solution-processed highly flexible organic solar cells
Authors: Wan Juanyong , Wen Rongjiang , Xia Yonggao , Dai Mingzhi , Huang Huihui , Xue Lingwei , Zhang Zhiguo , Fang Junfeng , Hui Kwun Nam , Fan Xi
Published: January 2021

We report efficient annealing-free solution-processed flexible organic solar cells (OSCs) integrated on a soft polyethylene substrate, with a high efficiency of 14.66% and a power-per-weight of 6.33 W g−1, close to that (15.73%) of thermally annealed control OSCs.
PbS QD-based photodetectors: future-oriented near-infrared detection technology
Authors: Yin Xingtian , Zhang Cong , Guo Yuxiao , Yang Yawei , Xing Yonglei , Que Wenxiu
Published: January 2021

With the increasing demand for near-infrared (NIR) detection in the fields of automation, military industry, communications and medical health, how to develop novel high quality and low cost NIR photodetectors has become a research hotspot in recent years.
Enhancing the plasmonic component of photonic–plasmonic resonances in self-assembled dielectric spheres on Ag
Authors: Moon Cheon Woo , Kim Geonyoung , Hyun Jerome Kartham
Published: January 2021

The plasmonic component of photonic–plasmonic hybrid resonances from a dielectric sphere array on Ag is substantially strengthened by introducing a thin Ag coating and TiO2 passivating layer above and below the PS sphere array, respectively.
A new simplified fundamental model‐based sensorless control method for surface‐mounted permanent magnet synchronous machines
Authors: Wu Ximeng , Zhu Zi‐qiang , Wu Zhan‐yuan
Published: January 2021

For sensorless control of surface‐mounted permanent magnet synchronous machines (SPMSMs), the major issue is in zero‐ and low‐speed ranges. Since back‐electromotive force (EMF) is proportional to speed, back‐EMF based methods fail at zero and low speed. A solution considering the starting process and low speed sensorless control is presented. A simplified fundamental model‐based method is proposed. Based on the simplified model, the measured stator currents in the stationary reference frame can be directly utilised for position estimation so that the sensorless control performance at low speed and starting is improved. Moreover, with the knowledge of rotor initial position sector information, a stable and reliable starting performance is achieved with the proposed method. The effectiveness of the proposed method is verified through experimental results.
Small‐signal analysis of multiple virtual synchronous machines to enhance frequency stability of grid‐connected high renewables
Authors: Kerdphol Thongchart , Rahman Fathin Saifur , Watanabe Masayuki , Mitani Yasunori , Hongesombut Komsan , Phunpeng Veena , Ngamroo Issarachai , Turschner Dirk
Published: January 2021

The virtual synchronous machine technology is considered as an important technique to effectively control the shortcomings of renewable energy‐based power electronics interfaces, providing backup inertia and regulating grid stability. Conventionally, the virtual synchronous machine with a large capacity is responsible for controlling the entire grid stability against renewable penetration. It is usually operated as a centralised control system. But what if virtual synchronous machines with small capacities are independently operated by their additional droop control schemes, and will they present better performance than the single virtual synchronous machine? This study proposes the multiple virtual synchronous machine system with different active power‐frequency (P‐f) droop characteristics to improve inertia support regarding frequency stability improvement. The comprehensive small‐signal modelling of the multiple virtual synchronous machine unit is designed to include the additional P‐f droop characteristics. Then, the dynamic characteristics (steady‐state and transient responses) and static stability of the multiple virtual synchronous machines are compared with the single virtual synchronous machine at the same rated capacity in both eigenvalue/sensitivity‐domain and time‐domain analysis. The obtained results reveal that the system with the presence of several virtual synchronous machines is more stable than the system with single virtual synchronous machine, maintaining stable and secure system operation during the contingency.
Characterisation of black skin stratum corneum by digital macroscopic images analysis
Authors: Azehoun‐Pazou Géraud M. , Assogba Kokou M. , Adegbidi Hugues , Vianou Antoine C.
Published: January 2021

Black skin medical images generally show very low contrast. Being in a global initiative of characterisation of black skin horny layer (stratum corneum) by digital images analysis, the authors in this study proposed a four‐step approach. The first step consists of differentiation between probable healthy skin regions and those affected. For that, they used an automatic classification system based on multilayer perceptron artificial neural networks. The network has been trained with texture and colour features. Best features selection and network architecture definition were done using sequential network construction algorithm‐based method. After classification, selected regions undergo a colour transformation, in order to increase the contrast with the lesion region. Thirdly, created colour information serves as the basis for a modified fuzzy c‐mean clustering algorithm to perform segmentation. The proposed method, named neural network‐based fuzzy clustering, was applied to many black skin lesion images and they obtained segmentation rates up to 94.67%. The last stage consists in calculating characteristics. Eight parameters are concerned: uniformity, standard deviation, skewness, kurtosis, smoothness, entropy, and average pixel values calculated for red and blue colour channels. All developed methods were tested with a database of 600 images and obtained results were discussed and compared with similar works.
The luminous and rapidly evolving SN 2018bcc
Authors: Karamehmetoglu E. , Fransson C. , Sollerman J. , Tartaglia L. , Taddia F. , De K. , Fremling C. , Bagdasaryan A. , Barbarino C. , Bellm E. C. , Dekany R. , Dugas A. M. , Giomi M. , Goobar A. , Graham M. , Ho A. , Laher R. R. , Masci F. J. , Neill J. D. , Perley D. , Riddle R. , Rusholme B. , Soumagnac M. T.
Published: January 2021

Context. Supernovae (SNe) Type Ibn are rapidly evolving and bright (MR, peak ∼ −19) transients interacting with He-rich circumstellar material (CSM). SN 2018bcc, detected by the ZTF shortly after explosion, provides the best constraints on the shape of the rising light curve (LC) of a fast Type Ibn.

Aims. We used the high-quality data set of SN 2018bcc to study observational signatures of the class. Additionally, the powering mechanism of SN 2018bcc offers insights into the debated progenitor connection of Type Ibn SNe.

Methods. We compared well-constrained LC properties obtained from empirical models with the literature. We fit the pseudo-bolometric LC with semi-analytical models powered by radioactive decay and CSM interaction. Finally, we modeled the line profiles and emissivity of the prominent He I lines, in order to study the formation of P-Cygni profiles and to estimate CSM properties.

Results. SN 2018bcc had a rise time to peak of the LC of 5.6−0.1+0.2 days in the restframe with a rising shape power-law index close to 2, and seems to be a typical rapidly evolving Type Ibn SN. The spectrum lacked signatures of SN-like ejecta and was dominated by over 15 He emission features at 20 days past peak, alongside Ca and Mg, all with VFWHM ∼ 2000 km s−1. The luminous and rapidly evolving LC could be powered by CSM interaction but not by the decay of radioactive 56Ni. Modeling of the He I lines indicated a dense and optically thick CSM that can explain the P-Cygni profiles.

Conclusions. Like other rapidly evolving Type Ibn SNe, SN 2018bcc is a luminous transient with a rapid rise to peak powered by shock interaction inside a dense and He-rich CSM. Its spectra do not support the existence of two Type Ibn spectral classes. We also note the remarkable observational match to pulsational pair instability SN models.
Advantages of formation non-agricultural land allocation projects based on GIS technologies
Authors: Babajanov Allabergan , Abdiramanov Rashid , Abdurahmanov Ilhom , Islomov Utkir
Published: January 2021

Based on the collection and study of official data, the main criteria for selecting a land plot using GIS (Geographic Information System) technologies for the construction of a water treatment plant are presented. The main stages of data analysis are determined when solving the question of the location of the building using ArcGIS, ArcMap, ArcCatalog and it is scientifically proven that the use of such programs when choosing land plots for such types of construction can save in large amounts of material and labour resources. Together with these, in the conducted study, a methodology was developed and presented for the formation of a database necessary for compiling similar GIS projects, as well as a methodology for a feasibility study for the implementation of land allotment projects for the construction of various economic facilities. The advantages of using GIS technology for non-agricultural land use projects, which are the main form of inter-farm land use, which is a modern measure aimed at rational land use, are described. Key factors and key indicators, as well as expected project results.
Indicators of the combine equipped with GPS receiver in sunflower harvesting
Authors: Ochildiev Otabek , Fozilov Golibjon , Achildiev Shodi , Karimov Maxmud , Ashurov Nurali
Published: January 2021

In sunflower harvesting for decreasing the grain loss and increasing using efficiency of the combines GIS technologies, namely combines equipped with GPS devices and control sensors provides good results. This is explained that by the fact that with a length of 400-500 mm, the cut baskets did not partially fall on the divider-guide, and with a length of 700-800 mm, seed losses increased due to uncut baskets, since with an increase in length the divider-guide bent some stems forward and did not cut them. Analyzing the studies of working process of the adapted grain harvester combine Dominator-130 that equipped with GPS receiver and grain level indicator sensor in sunflower harvesting defined optimal parameters its header, as the following values: the length of the divider-guide (lТ) - 0.6 m, the gap between the divider-guides (ST) - 0.1 m, the installation angle of the divider-guide relative to the bottom of the header (βТ) - 5 degrees. With these parameters, the combine that has adapted header for harvesting sunflower meets the agro technical requirements for harvesting sunflower.
Analysis of modular transport systems functioning in selected European countries
Authors: Dzioba Anna , Markiewicz Marietta , Gutsche Jan
Published: January 2021

This study presents an analysis of transport modular systems in selected European countries. The European Modular System is characterized and legal acts concerning transport means and systems used for this form of transport are discussed. The study focuses on the European countries which take advantage of this system and the scope of its utilization. Based on the literature and source materials, a comparative analysis was performed and purposefulness the European Modular Systems in Europe was determined.
Coronary Artery Disease Phenotype Detection in an Academic Hospital System Setting
Authors: Joseph Amy , Mullett Charles , Lilly Christa , Armistead Matthew , Cox Harold J. , Denney Michael , Varma Misha , Rich David , Adjeroh Donald A. , Doretto Gianfranco , Neal William , Pyles Lee A.
Published: January 2021

Background The United States, and especially West Virginia, have a tremendous burden of coronary artery disease (CAD). Undiagnosed familial hypercholesterolemia (FH) is an important factor for CAD in the U.S. Identification of a CAD phenotype is an initial step to find families with FH.

Objective We hypothesized that a CAD phenotype detection algorithm that uses discrete data elements from electronic health records (EHRs) can be validated from EHR information housed in a data repository.

Methods We developed an algorithm to detect a CAD phenotype which searched through discrete data elements, such as diagnosis, problem lists, medical history, billing, and procedure (International Classification of Diseases [ICD]-9/10 and Current Procedural Terminology [CPT]) codes. The algorithm was applied to two cohorts of 500 patients, each with varying characteristics. The second (younger) cohort consisted of parents from a school child screening program. We then determined which patients had CAD by systematic, blinded review of EHRs. Following this, we revised the algorithm by refining the acceptable diagnoses and procedures. We ran the second algorithm on the same cohorts and determined the accuracy of the modification.

Results CAD phenotype Algorithm I was 89.6% accurate, 94.6% sensitive, and 85.6% specific for group 1. After revising the algorithm (denoted CAD Algorithm II) and applying it to the same groups 1 and 2, sensitivity 98.2%, specificity 87.8%, and accuracy 92.4; accuracy 93% for group 2. Group 1 F1 score was 92.4%. Specific ICD-10 and CPT codes such as “coronary angiography through a vein graft” were more useful than generic terms.

Conclusion We have created an algorithm, CAD Algorithm II, that detects CAD on a large scale with high accuracy and sensitivity (recall). It has proven useful among varied patient populations. Use of this algorithm can extend to monitor a registry of patients in an EHR and/or to identify a group such as those with likely FH.
Three Cases of Joubert Syndrome in a Consanguineous Syrian Family and a Interesting Case of Multinational Collaboration
Authors: Petrović Davor , Čulić Vida , Swinderek-Alsayed Zofia
Published: January 2021

Joubert syndrome (JS) is a rare congenital, autosomal recessive disorder characterized by a distinctive brain malformation, developmental delay, ocular motor apraxia, breathing abnormalities, and high clinical and genetic heterogeneity. We are reporting three siblings with JS from consanguineous parents in Syria. Two of them had the same homozygous c.2172delA (p.Trp725Glyfs*) AHI1 mutation and the third was diagnosed prenatally with magnetic resonance imaging. This pathogenic variant is very rare and described in only a few cases in the literature. Multinational collaboration could be of benefit for the patients from undeveloped, low-income countries that have a low-quality health care system, especially for the diagnosis of rare diseases.
The stakeholder model: its relevance, concept, and application in the Indonesian banking sector
Authors: Rissy Yafet Yosafet Wilben
Published: January 2021

This article examines the current Indonesian Financial Service Authority (IFSA) regulations on corporate governance that deal with the relevance, concept, and application of the stakeholder model in the Indonesian banking sector. This study shows that the current IFSA regulations on corporate governance in the Indonesian banking sector encourage the application of the stakeholder model. However, they contain a vague definition of a stakeholder, fail to properly identify the legitimate stakeholders of the Indonesian banking sector, and provide no principles that can be used to align bank stakeholders’ interests. IFSA should revise these regulations so that they are more compatible with the theoretical basis and international best practices. This can be done through providing a concise definition of the concept of a stakeholder and offering normative and practical principles to be used when identifying the Indonesian banking sector legitimate stakeholders and aligning stakeholders’ interests.
Position–momentum decomposition of linear operators defined on algebras of polynomials
Authors: Stan A. I. , Popa G. , Dutta R.
Published: January 2021

We present first a set of commutator relationships involving the joint quantum, semi-quantum, and number operators generated by a finite family of random variables, having finite moments of all orders, and show how these commutators can be used to recover the joint quantum operators from the semi-quantum operators. We show that any linear operator defined on an algebra of polynomials or the polynomial random variables, generated by a finite family of random variables, having finite moments of all orders, can be written uniquely as an infinite sum of compositions of the multiplication operators, generated by these random variables, and the partial derivative operators. In the terms of this sum, each multiplication operator is placed to the left side of each partial derivative operator. We provide many examples concerning the decomposition of some classic operators.
Phase singularity annihilation in plasmonic nano-apertures via epsilon-near-zero metamaterials
Authors: Ghasemzadeh F. , Rashed A. R. , Caglayan H.
Published: January 2021

In this work, we performed an extensive theoretical and experimental study to unveil the underlying mechanisms related to the intensified transmittance in epsilon-near-zero (ENZ)-integrated plasmonic nano-apertures. The occurrence of phase singularities at the incident side of plasmonic nano-apertures results in the reduction in transmittance. We show that transmittance enhancement in ENZ-integrated nano-slits is attributed to the annihilation of the phase singularities by the ENZ layer and subsequently the modification in plasmonic fields of metallic apertures. The singularity annihilation via ENZ metamaterials eliminates the abrupt changes in the phase of the Poynting vector underneath the slit, which results in a stronger cavity resonance inside the aperture. Due to this fact, a nano-aperture on top of an ENZ metamaterial is the only effective configuration to enhance the transmittance in ENZ-integrated nano-apertures. Hence, our study reveals the physics of the transmittance enhancement through ENZ-integrated plasmonic nano-apertures.
Ultra-stretchable, self-adhesive, transparent, and ionic conductive organohydrogel for flexible sensor
Authors: Sun Chuanyue , Hou Chengyi , Zhang Hui , Li Yaogang , Zhang Qinghong , Wang Hongzhi
Published: January 2021

Conductive hydrogels are an ideal bio-integrated soft material and show great potential in soft sensors. However, it remains a great challenge to develop an integrated conductive gel combining excellent environmental stability and mechanical properties. Herein, we synthesize a transparent, self-adhesive conductive organohydrogel with excellent environmental stability and UV-blocking performance by constructing multiple cross-links between tannic acid, polyacrylamide, and polyvinyl alcohol. The addition of vinyl hybrid silica nanoparticles can promote dynamic cross-linking of polymer networks and endow organohydrogels with superior mechanical performance (>1800%, 320 kPa). Concurrently, the binary solvent system comprising water and ethylene glycol enables organohydrogels to accommodate different application environments (from −40 °C to 40 °C). Notably, with the incorporation of tannic acid, organohydrogels exhibit lasting and repeatable adhesion (80 kPa), as well as good UV-blocking (>90%). Furthermore, these conductive organohydrogels with great strain sensitivity were used as strain sensors to monitor and distinguish large movements (soft robot movements) and subtle human movements (smiling and electrocardiograph signal) at different temperatures. The conductive organohydrogels have great potential in healthcare monitoring and smart wearable soft electronic devices.
The retranslation of Chinese political texts
Authors: Pan Feng , Li Tao
Published: January 2021

The past three decades have witnessed an increase in research on retranslation. Drawing on Critical Discourse Analysis,
this study examines the retranslation of political texts – specifically Work Reports by the Communist Party of China – as a special genre in
its own right. By concentrating on the retranslation of a recurring set of Chinese political concepts, culture-specific items, and preferred
usages into English from the early 1990s to the late 2010s, this study shows how and why the retranslations have been carried out, as
motivated by the evolving ideologies of the original author – the Communist Party of China. The retranslations are shown to be influenced by
the broader social, economic, and political dynamics within China, rather than by prevailing factors within the receiving culture or
variables associated with the individual translators, as is commonly suggested in the literature. Our findings add to the existing body of
research into retranslation by extending the genres and contexts of retranslation research.
Methanol formation chemistry with revised reactions scheme
Authors: Alekseevna Sokolova Valeriia
Published: January 2021

The aim of the presented work is to analyze the impact of experimentally evaluated reactions of hydrogen abstraction on surfaces of interstellar grains on the chemical evolution of methanol and its precursors on grains and in the gas phase under conditions of a cold dark cloud and during the collapse of a translucent cloud into a dark cloud. Analysis of simulation results shows that those reactions are highly efficient destruction channels for HCO and H2CO on grain surfaces, and significantly impact the abundances of almost all molecules participating in the formation of CH3OH. Next, in models with those reactions, maximum abundances of methanol in gas and on grain surfaces decrease by more than 2–3 orders of magnitude in comparison to models without surface abstraction reactions of hydrogen. Finally, we study the impact of binding energies of CH2OH and CH3O radicals on methanol chemistry.
Research and application of reanalysis data for radio astronomical site testing
Authors: Li Ming-Shuai , Li Rui , Wang Na , Zheng Xing-Wu
Published: January 2021

Selecting a good site for ground-based astronomy is very important. Based on the ERA-Interim global reanalysis data, this paper studied the atmospheric conditions of the Qitai Telescope (QTT) site from the aspects of absolute humidity, mixing ratio and precipitable water vapor (PWV). Error estimations of meteorological parameters are also analyzed. These primary results show that the QTT site has obvious advantages in terms of conditions with much less atmospheric water vapor than two well-known existing sites with 100-meter-aperture radio telescopes in the world. In addition, due to the influence of atmospheric water vapor on radio observations, the atmospheric transmittance for each frequency band of the site are simulated, and the atmospheric opacity is also calculated as well as Planck radiation brightness. Based on these results, the effective observational time of different bands is further estimated.
Laboratory study of the formation of fullerene (from smaller to larger, C44 to C70)/anthracene cluster cations in the gas phase
Authors: Zhang De-Ping , Yang Yuan-Yuan , Hu Xiao-Yi , Zhen Jun-Feng
Published: January 2021

The formation and evolution mechanism of fullerenes in the planetary nebula or in the interstellar medium are still not understood. Here, we present the study on the cluster formation and the relative reactivity of fullerene cations (from smaller to larger, C44 to C70) with anthracene molecule (C14H10). The experiment is performed in an apparatus that combines a quadrupole ion trap with a time-of-flight mass spectrometer. By using a 355 nm laser beam to irradiate the trapped fullerenes cations (C60
+ or C70
+), smaller fullerene cations C(60 – 2n)
+, n = 1 – 8 or C(70 – 2m)
+, m = 1 – 11 are generated, respectively. Then reacting with anthracene molecules, series of fullerene/anthracene cluster cations are newly formed (e.g., (C14H10)C(60 – 2n)
+, n = 1 – 8 and (C14H10)C(70 – 2m)
+, m = 1 – 11), and slight difference of the reactivity within the smaller fullerene cations are observed. Nevertheless, smaller fullerenes show obviously higher reactivity when comparing to fullerene C60
+ and C70
+. A successive loss of C2 fragments mechanism is suggested to account for the formation of smaller fullerene cations, which then undergo addition reaction with anthracene molecules to form the fullerene-anthracene cluster cations. It is found that the higher laser energy and longer irradiation time are key factors that affect the formation of smaller fullerene cations. This may indicate that in the strong radiation field environment (such as photon-dominated regions) in space, fullerenes are expected to follow the top-down evolution route, and then form small grain dust (e.g., clusters) through collision reaction with co-existing molecules, here, smaller PAHs.
The influence of the observational strategies of pulsar timing on the properties of pulsar clocks
Authors: Zhang Zhe-Hao , Tong Ming-Lei , Zhao Cheng-Shi , Zhu Xing-Zhi , Gao Feng
Published: January 2021

Pulsars are very stable spinning stars, which have the potential to application in the work of time-keeping and autonomous navigation in deep space. For time application, an individual pulsar can be regarded as a clock. The accuracy and stability of a pulsar clock are mainly determined by various timing noises and the measurement errors; however, they would be affected by the concrete observational strategy. Taking four millisecond pulsars from the first data released by International Pulsar Timing Array (IPTA) as an example, we investigated the influences of different observational strategies on the properties of pulsar clocks by removing some data in various ways. We find that the long-term stabilities of pulsar clocks are nearly not affected by increasing the observational cadence with a fixed time span. It is also found that the capabilities of prediction by pulsar clocks are also hardly affected by different observational strategies, which is reflected by both the stable weighted root-mean-square (wrms) and the stability of the resulting pre-fit timing residuals, unless the data span is too short or the data period is too far from the start of prediction.
Segments of spiral arms of the Galaxy traced by classical Cepheids: effects of age heterogeneity
Authors: Veselova Angelina V. , Nikiforov Igor’ I.
Published: January 2021

We investigated the dependence of the parameters of the segments of spiral arms of the Galaxy on the age of classical Cepheids. The catalog of Cepheids (Mel’nik et al.) was divided into two samples— relatively young (P > 9d) and relatively old (P < 9d) objects. The parameters of the spiral structure were determined both for two samples separately and jointly for the combination of two systems of segments traced by young and old objects. For most of the segments, their parameters for young and old objects differ significantly. Taking into account the difference between the two segment systems, we obtained the estimate R
0 equal to

7.23

−
0.18

+
0.19

kpc, which in the modern Large Magellanic Cloud (LMC) calibration corresponds to the value of

R
0

=

8.08

−
0.20

+
0.21

|

stat
.

−
0.36

+
0.38

|

cal
.

kpc. It is shown that the displacement between the segments is not reduced to the effect of differential rotation only. To interpret this displacement for objects of Perseus and Sagittarius-2 segments, we carried out a dynamic modeling of the change in the position of the segment points when moving in the smooth gravitational field of the Galaxy. At the angular velocity of rotation of the spiral pattern Ωp = 25.2 ± 0.5 km s−1 kpc−1 (Dambis et al.) the observed displacement between segments on young and old objects can be explained by the amplitude of spiral perturbations of the radial velocity of u = 10 ± 1.5 km s−1. For the constructed double system of spiral segments, it is demonstrated that the assumption of constancy of the pitch angles within each segment and the assumption that the pole of the spiral pattern is in the direction of the nominal center of the Galaxy do not contradict the data within the range of uncertainty.
Depolarizing isotropic collisions of the CN solar molecule with electrons
Authors: Derouich Moncef , Mustajab Fainana , Qutub Saleh , Ahmad Badruddin Zaheer
Published: January 2021

Existence of linear polarization, formed by anisotropic scattering in the photosphere, has been demonstrated observationally as well as theoretically and is called second solar spectrum (SSS). The SSS is distinguished by its structure, which is rich in terms of information. In order to analyze the SSS, it is necessary to evaluate the (de)polarizing effect of isotropic collisions between CN solar molecules and electrons or neutral hydrogen atoms. This work is dedicated to calculations of the polarization transfer rates associated with CN–electron isotropic collisions. We show that usual rates serve as a proxy for polarization transfer rates. Then, we take advantage of available usual excitation collisional rates obtained via sophisticated quantum methods in order to derive the polarization transfer rates for the X
2Σ+– B
2Σ+ (violet) and X
2Σ+–A
2Π (red) systems of CN. Our approach is based on the infinite order sudden (IOS) approximation and can be applied for other solar molecules. We discuss the effectiveness of collisions with electrons on the SSS of the CN lines. Our results contribute to reducing the degree of complication in modeling the formation of the SSS of CN.
A frequency filter of backscattered light of stimulated Raman scattering due to the Raman rescattering in the gas-filled hohlraums
Authors: Hao Liang , Huo Wen Yi , Liu Zhanjun , Li Jun , Zheng Chunyang , Ren Chuang
Published: January 2021

The coupling evolutions of stimulated Raman scattering (SRS) and Raman rescattering (re-SRS) are investigated under the parameter conditions of relevance to the gas-filled hohlraum experiments at the National Ignition Facility by using the nonenveloped fluid code FLAME. It is found that re-SRS works as a frequency filter of the backscattered light of SRS in the gas region. The low frequency modes of scattered light originated from a higher density region would stimulate re-SRS and be heavily depleted by re-SRS near the region of their quarter critical density. The energy in daughter waves of re-SRS is deposited in the gas plasmas. The large amplitude of the daughter Langmuir wave of re-SRS would stimulate cascade Langmuir decay instabilities and induce obvious low frequency density modulations, which can further result in the inflation of high frequency modes of scattered light of SRS at densities lower than the growth region of re-SRS.
Combinatorics for calculating expectation values of functions in systems with evolution governed by stochastic differential equations
Authors: Ohkubo Jun
Published: January 2021

Stochastic differential equations are widely used in various fields; in particular, the usefulness of duality relations has been demonstrated in some models such as population models and Brownian momentum processes. In this study, a discussion based on combinatorics is made and applied to calculate the expectation values of functions in systems in which evolution is governed by stochastic differential equations. Starting with the duality theory of stochastic processes, some modifications to the interpretation and usage of time-ordering operators naturally lead to discussions on combinatorics. For demonstration, the first and second moments of the Ornstein–Uhlenbeck process are re-derived from the discussion on combinatorics. Furthermore, two numerical methods for practical applications are proposed. One method is based on a conventional exponential expansion and the Padé approximation. The other uses a resolvent of a time-evolution operator, along with the application of the Aitken series acceleration method. Both methods yield reasonable approximations. Particularly, the resolvent and Aitken acceleration show satisfactory results. These findings will provide a new way of calculating expectations numerically and directly without using time-discretization.
The cubic interpolation spline for functions with boundary layer on a Bakhvalov mesh
Authors: Blatov I A , Dobrobog N V , Kitaeva E V
Published: January 2021

The problem of cubic spline interpolation on the Bakhvalov mesh of functions with region of large gradients is considered. Asymptotically accurate error estimates O(N
−4) are obtained for a class of functions with an exponential boundary layer in case 1/N ≤ ε, where N is number of nodes, ε is small parameter. In case ε ≤ 1/N we have experimentally shown that the error estimates of traditional spline interpolation are not uniform in a small parameter, and the error itself can increase indefinitely when the small parameter tends to zero at a fixed number of nodes N. A modified cubic spline is proposed for which uniform estimates of the order O(N
−4) have been experimentally confirmed.
Evolutionary synthesis of nonlinear models based on metaheuristic programming and templates
Authors: Monakhov Oleg
Published: January 2021

The application of a metaheuristic programming (MP) algorithm based on various bio-inspired algorithms for the evolutionary (metaheuristic) synthesis of nonlinear models is considered. The described approach of evolutionary synthesis uses a sequential operator structure of the chromosome, templates (with some undefined functions and parameters) of the models and the given sets of pairs of input and output data. The influence of the degree of specialization of the template on the characteristics of the search algorithm in the metaheuristic synthesis of nonlinear models defined by ordinary differential equations with undetermined functions and parameters is studied. Estimates of the complexity of this algorithm are obtained, and a significant reduction in the search time when using templates in the process of the evolutionary synthesis is shown.
Mathematical modeling of Russian northern coastal waters in the shallow water approximation
Authors: Elizarova T G , Ivanov A V , Kuleshov A A
Published: January 2021

In this paper, the authors present a model for computing a coastal waters flow in the shallow seas. The software implementation of the model consists in coupling the global software and the local hydrodynamic computations. The authors describe the use of the joint two computational packages: the global model for the ocean dynamics NEMO (Nucleus for European Modelling of the Ocean) which provides the initial and boundary conditions and the code WRF (Weather Research and Forecasting) for predicting meteorological conditions is used to calculate the wind loads. A hydrodynamic model based on the shallow water (SW) approximation is used to compute the coastal waters flow within a local domain, typically, 1000 km in size. The software implementation of the algorithm is based on regularized SW equations. As an example, the authors have computed the flow of the coastal waters in the vicinity of the Kara Strait. The study carried out demonstrate that all three algorithms successfully combined in the framework of the local computation and give the consistent results.
Computer simulation of coronas, glories and fogbows in atmospheric clouds and fogs
Authors: Zakovryashin A V , Prigarin S M
Published: January 2021

This paper deals with the development of software that allows one to compute the scattering phase functions of the optical radiation in polydisperse media consisting of spherical particles, based on the Mie scattering theory. The software also enables computer visualization of such optical phenomena as rainbows, glories and coronas. A special technique is used to significantly accelerate the integration over the radius of scattering particles and to increase the calculation rate of the scattering phase functions. Using the software developed, we have performed a detailed analysis of the scattering phase functions for a large number of well-known cloud and fog models, and have created computer images of optical phenomena (rainbows, glories, and coronas) that are inherent to the considered models.
Regularization of algorithms for estimation of errors of differential equations approximate solutions
Authors: Rogalev A N , Feodorova N A
Published: January 2021

When estimating the error of numerical solutions of ordinary differential equations, it is proposed to use the regularization of error estimation algorithms for approximate solutions. Regularization is considered as the use of additional a priori information about the numerical solution. A priori information is estimated by the method of the inverse error analysis, which implements the transformation of the statement of the problem of evaluating the accuracy of the numerical solution. In this case, the problem is selected so that the approximate solution is the exact solution of the transformed problem, close to the original problem. It is also possible to add some additional restrictions to the conditions of the problem. This allows us to solve the incorrectly posed problems of estimating errors in numerical solutions, which in most cases are unstable. It is known that earlier in the numerical solution of linear algebra problems the inverse error analysis was used by Wilkinson J. and also Voevodin V.V., application of the inverse error analysis in other areas of numerical analysis can be noted. Using direct and inverse error analysis Voevodin V.V. effectively calculated majorants of rounding errors in the most important methods of linear algebra and significantly developed the method of inverse error analysis.. However, the regularization process associated with the reverse analysis of errors has not been previously studied. The article discusses the characteristics of regularization in the inverse analysis of errors in the numerical solution of ordinary differential equations with initial data. The regularization of error estimation algorithms has advantages in the numerical solution of ordinary differential equations of real models of physics and technology.
The control problem for the heat equation in the case of a composite material
Authors: Tanana V P , Markov B A
Published: January 2021

In modern technology there are devices whose details are subject to thermal effects. As a result, the properties of materials may change in parts. In turn, this leads to the failure of the device. You can control surface temperature to protect components from excessive heat. The temperature measuring device cannot be placed at the point where the heating takes place, since the heating temperature is too high. On the other hand, the temperature of the outer side of the protective layer itself is of little interest: you need to know the temperature on the surface of the material. Therefore, one can either, knowing the temperature at the material-protective layer media section, solve the inverse problem, or solve the heating control problem. In this paper, we propose to consider the problem of controlling heating under the condition of controlling the temperature of the interface. We consider the problem on a half-line, and the following sections are identified in the problem: the heating region, a small thickness of the protective layer, the region occupied by the material, and the semi-infinite region in which the material interacts with the environment. At the same time, we consider such a coefficient of thermal conductivity that it is constant in each of the regions, but it experiences a first-order discontinuity at the interfaces. This makes it impossible to build a classical solution to the problem in the entire solution area, and we build solutions that are classic, each in its own subregion, and that meets the matching conditions at the interfaces. The control problem is as follows: the heating function, on the one hand, should be maximum all the time, and on the other, the temperature at the interface should not exceed a certain critical value (for example, the melting temperature of the material). The constructed solution of the problem is simple, but requires rather cumbersome proofs.
The Barnes — Hut-type algorithm in 2D Lagrangian vortex particle methods
Authors: Ryatina E , Lagno A
Published: January 2021

The Lagrangian vortex particle method for two-dimensional flow simulation around airfoils is considered. Generally, the most time-consuming operation in the vortex method is vortex particles interaction simulation, especially if it is performed directly “point-to-point” for all pairs of particles. The result of such operation is vortex particles convective velocities. This problem is similar to the N-body problem and has squared computational complexity O(N2). The only efficient approach for its solution in a reasonable time for large N is to use approximate fast algorithms. The fast method suggested by Barnes and Hut having logarithmic computational complexity is considered for the mentioned problem of convective velocities computation. It also has been adapted for other operations in the vortex method such as a system of algebraic equations iterative solution and efficient right-hand side computation. As the result, the Barnes — Hut method allows reducing the whole time of calculations by several tens of times.