bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogenetic origins of cranial convergence between the extinct marsupial thylacine and placental gray wolf
Authors: Newton Axel H. , Weisbecker Vera , Pask Andrew J. , Hipsley Christy A.
Published: January 2021

Phenotypic convergence, describing the independent evolution of similar characteristics, offers unique insights into how natural selection influences developmental and molecular processes to generate shared adaptations. The extinct marsupial thylacine and placental gray wolf represent one of the most extraordinary cases of convergent evolution in mammals, sharing striking cranial similarities despite 160 million years of independent evolution. We digitally reconstructed their cranial ontogeny from birth to adulthood to examine how and when convergence arises through patterns of allometry, mosaicism, modularity, and integration. We find the thylacine and wolf crania develop along nearly parallel growth trajectories, despite lineage-specific constraints and heterochrony in timing of ossification. These constraints were found to enforce distinct cranial modularity and integration patterns during development, which were unable to explain their adult convergence. Instead, we identify a developmental origin for their convergent cranial morphologies through patterns of mosaic evolution, occurring within bone groups sharing conserved embryonic tissue origins. Interestingly, these patterns are accompanied by homoplasy in gene regulatory networks associated with neural crest cells, critical for skull patterning. Together, our findings establish empirical links between adaptive phenotypic and genotypic convergence and provides a digital resource for further investigations into the developmental basis of mammalian evolution.
Chimpanzee histology and functional brain imaging show that the paracingulate sulcus is not human-specific
Authors: Amiez Céline , Sallet Jérôme , Novek Jennifer , Hadj-Bouziane Fadila , Giacometti Camille , Andersson Jesper , Hopkins William D. , Petrides Michael
Published: January 2021

The paracingulate sulcus -PCGS- has been considered for a long time to be specific to the human brain. Its presence/absence has been discussed in relation to interindividual variability of personality traits and cognitive abilities. Recently, a putative PCGS has been observed in chimpanzee brains. To demonstrate that this newly discovered sulcus is the homologue of the PCGS in the human brain, we analyzed cytoarchitectonic and resting-state functional magnetic resonance imaging data in chimpanzee brains which did or did not display a PCGS. The results show that the organization of the mid-cingulate cortex of the chimpanzee brain is comparable to that of the human brain, both cytoarchitectonically and in terms of functional connectivity with the lateral frontal cortex. These results demonstrate that the PCGS is not human-specific but is a shared feature of the primate brain since at least the last common ancestor to humans and great apes ~6 mya.
Pseudosparse neural coding in the visual system of primates
Authors: Lehky Sidney R. , Tanaka Keiji , Sereno Anne B.
Published: January 2021

When measuring sparseness in neural populations as an indicator of efficient coding, an implicit assumption is that each stimulus activates a different random set of neurons. In other words, population responses to different stimuli are, on average, uncorrelated. Here we examine neurophysiological data from four lobes of macaque monkey cortex, including V1, V2, MT, anterior inferotemporal cortex, lateral intraparietal cortex, the frontal eye fields, and perirhinal cortex, to determine how correlated population responses are. We call the mean correlation the pseudosparseness index, because high pseudosparseness can mimic statistical properties of sparseness without being authentically sparse. In every data set we find high levels of pseudosparseness ranging from 0.59–0.98, substantially greater than the value of 0.00 for authentic sparseness. This was true for synthetic and natural stimuli, as well as for single-electrode and multielectrode data. A model indicates that a key variable producing high pseudosparseness is the standard deviation of spontaneous activity across the population. Consistently high values of pseudosparseness in the data demand reconsideration of the sparse coding literature as well as consideration of the degree to which authentic sparseness provides a useful framework for understanding neural coding in the cortex.
Charge transport and thermoelectric conversion in solution-processed semicrystalline polymer films under electrochemical doping
Authors: Ito Hiroshi , Mada Hiroaki , Watanabe Katsuya , Tanaka Hisaaki , Takenobu Taishi
Published: January 2021

Charge transport and thermoelectric conversion mechanisms in doped semicrystalline polymer films are key issues in the field of wearable electronics, whereas the complex film structure consisting of crystalline domains and non-crystalline boundaries prevents sufficient understanding of them. In this study, we fully clarify the roles of the domains and the boundaries in a typical semicrystalline polymer on macroscopic charge transport under continuous electrochemical doping. In the crystalline domains, a multi-step transformation of the transport properties from effectively metallic behavior to weak localization (WL) to variable-range hopping (VRH) is found with decreasing temperature and doping level. On the other hand, at the domain boundaries, the effectively metallic conduction changes directly to VRH. Based on these results, the extremely complicated phase diagram, including the coexistence of the WL and VRH processes, is well explained. The proposed transport mechanism further explains the thermoelectric properties of the film.
Fluorescence assay for the determination of glutathione based on a ring-fused 2-pyridone derivative in dietary supplements
Authors: Kasprzyk Wiktor , Koper Filip , Flis Agata , Szreder Dominika , Pamuła Elżbieta , Bogdał Dariusz , Wybraniec Sławomir , Ortyl Joanna , Świergosz Tomasz
Published: January 2021

Herein, a novel fluorescent method for the determination of GSH levels in aqueous solutions involving the utilization of citric acid as a derivatization reagent was developed.
Sandwich shelled TiO2@Co3O4@Co3O4/C hollow spheres as anode materials for lithium ion batteries
Authors: Liu Zheng , Yu Mengkang , Wang Xiaodan , Lai Fengyu , Wang Chao , Yu Nan , Sun Hongxia , Geng Baoyou
Published: January 2021

A sandwich shelled hollow TiO2@Co3O4@Co3O4/C composite is synthesized by consecutive coating of Co3O4 nanosheets and TiO2 particles on Co3O4/C hollow spheres.
Pyridazine-bridged expanded rosarin and semi-rosarinogen
Authors: Xu Kui , Zhang Xiaoshuai , Liu Guopeng , Ma Wanzun , Yin Yu , Yin Ying , Chen Xi , Zhao Xinyun , Sessler Jonathan L. , Zhang Zhan
Published: January 2021

The synthesis of the pyridazine-bridged expanded rosarin 1 and a reduced precursor, semi-rosarinogen 2, is reported; both provided a colorimetric response when exposed to thiols.
How does mass transfer influence electrochemical carbon dioxide reduction reaction? A case study of Ni molecular catalyst supported on carbon
Authors: Guo Chang , Liu Song , Chen Zhiwen , Li Bingyu , Chen Lixin , Singh Chandra Veer , Liu Bin , Mao Qing
Published: January 2021

A series of heterogeneous molecular catalysts by immobilizing nickel(II) phthalocyanine (NiPc) onto different carbon supports were constructed to study the influence of the catalyst's microstructure on the performance of CO2 electroreduction.
Rhodium-catalyzed carbonylative coupling of alkyl halides with thiols: a radical process faster than easier nucleophilic substitution
Authors: Ai Han-Jun , Rabeah Jabor , Brückner Angelika , Wu Xiao-Feng
Published: January 2021

A rhodium-catalyzed radical-based carbonylative coupling of alkyl halides with thiolphenols has been realized. Thioesters were isolated in good yields in general.
Pre-organisation of ligand donor sets modulates the supramolecular structure of bis(pyridyl–imine) silver(i) chelates
Authors: Venter Chané , Akerman Matthew P.
Published: January 2021

Ligands comprising o-, m- or p-phenylenediamine coupled to pyridine-2-carbaldehyde were coordinated to silver(i). By controlling the positions of the ligand donor sets, the supramolecular structure of the coordination compounds was manipulated.
Four dual-functional luminescent Zn(ii)-MOFs based on 1,2,4,5-benzenetetracarboxylic acid with pyridylbenzimidazole ligands for detection of iron(iii) ions and acetylacetone
Authors: Shi Yong-Sheng , Yu Qiang , Zhang Jian-Wei , Cui Guang-Hua
Published: January 2021

Four Zn-MOFs with different topological types were synthesized and characterized, MOFs 1–4 have excellent sensitivity, selectivity, recyclability and structural stabilities for detecting acac/Fe3+ in the naked eye range.
A small molecule with a big scissoring effect: sodium dodecyl sulfate working on two-dimensional metal–organic frameworks
Authors: Luo Qing , Ding Zhen , Sun Huamin , Cheng Zhen , Shi Naien , Song Chuanyuan , Han Min , Gu Daqing , Yi Mingdong , Sun Yujie , Xie Linghai , Huang Wei
Published: January 2021

In this paper, a SDS-directed solution method was developed to synthesize a series of well-dispersed two-dimensional non-layered metal–organic frameworks (MOFs) (ZIF-8 & ZIF-67) and layered MOFs (ZnTCPP & CuBDC).
Speed-dependent adaptive partitioning in QM/MM MD simulations of displacement damage in solid-state systems
Authors: Yang Zeng-hui
Published: January 2021

The SDAC method results in a more consistent QM/MM partitioning over time than the previous AC method.
Broadband photomultiplication organic photodetectors
Authors: Liu Meng-yao , Wang Jian , Yang Kai-xuan , Liu Ming , Zhao Zi-jin , Zhang Fu-jun
Published: January 2021

Broadband photomultiplication type organic photodetectors (PM-OPDs) were successfully fabricated by employing a double-layered scheme with a photon harvesting layer and a PM layer.
Temperature and pressure-induced strains in anhydrous iron trifluoride polymorphs
Authors: Recio-Poo M. , Lobato A. , Otero-de-la-Roza A. , Salvadó M. A. , Arroyo-de Dompablo M. E. , Recio J. M.
Published: January 2021

Under negative pressure or positive strains, alpha-FeF3 undergoes phase transitions toward wider pore aperture structures that are more convenient for ion battery applications.
Taming the excited state reactivity of imines – from non-radiative decay to aza Paternò–Büchi reaction
Authors: Kandappa Sunil Kumar , Valloli Lakshmy Kannadi , Ahuja Sapna , Parthiban Jayachandran , Sivaguru J.
Published: January 2021

This review highlights the excited state characteristics of imines and processes that govern their photochemical and photophysical properties.
The role of coordination compounds in virus research. Different approaches and trends
Authors: Maldonado Noelia , Amo-Ochoa Pilar
Published: January 2021

Coordination compounds as antiviral substances: from their use as antiviral drugs to novel approaches such as their use as nanocarriers of antiviral drugs, for wrapping viruses, or to release antiviral agents.
Highly efficient Meerwein–Ponndorf–Verley reductions over a robust zirconium-organoboronic acid hybrid
Authors: Song Jinliang , Hua Manli , Huang Xin , Visa Aurelia , Wu Tianbin , Fan Honglei , Hou Minqiang , Zhang Zhaofu , Han Buxing
Published: January 2021

Synergetic effect of Zr4+ and borate in zirconium organoborate could significantly promote the Meerwein–Ponndorf–Verley reduction of various biomass-based carbonyl compounds.
Gold nanoparticle-mediated non-covalent functionalization of graphene for field-effect transistors
Authors: Shin Dongha , Kim Hwa Rang , Hong Byung Hee
Published: January 2021

Consecutive treatment of gold nanoparticles and thiol-SAM molecules induce the recovery of electronic state of pristine graphene.
Retraction: A bio-based piezoelectric nanogenerator for mechanical energy harvesting using nanohybrid of poly(vinylidene fluoride)
Authors: Rulka Anna
Published: January 2021

Retraction for ‘A bio-based piezoelectric nanogenerator for mechanical energy harvesting using nanohybrid of poly(vinylidene fluoride)’ by Pralay Maiti et al., Nanoscale Adv., 2019, 1, 3200–3211, DOI: 10.1039/C9NA00214F.
The synthesis, biological evaluation and fluorescence study of chromeno[4,3-b]pyridin/quinolin-one derivatives, the backbone of natural product polyneomarline C scaffolds: a brief review
Authors: Patra Prasanta , Kar Gandhi Kumar
Published: January 2021

This review presents the synthesis, biological and fluorescence study of chromeno[4,3-b]pyridin/quinolin-onesviaclassical reactions including metal-catalyzed and green reaction protocols.
Magnetization of biochar nanoparticles as a novel support for fabrication of organo nickel as a selective, reusable and magnetic nanocatalyst in organic reactions
Authors: Moradi Parisa , Hajjami Maryam
Published: January 2021

Waste recycling is important process in green chemistry and economic efficiency. Herein, magnetized biochar nanoparticles were modified under green and environmentally friendly method and further were applied as reusable catalyst in organic reactions.
Monodisperse-porous cerium oxide microspheres as a new support with appreciable catalytic activity for a composite catalyst in benzyl alcohol oxidation
Authors: Hamaloğlu Kadriye Özlem , Tosun Rukiye Babacan , Ulu Serap , Kayı Hakan , Kavaklı Cengiz , Kavaklı Pınar Akkaş , Kip Çiğdem , Tuncel Ali
Published: January 2021

Monodisperse porous ceria microspheres as a support with individual catalytic activity, facile post-functionalization and high surface area for heterogeneous catalysis.
Engineering Z-system hybrids of 0D/2D F-TiO2 quantum dots/g-C3N4 heterostructures through chemical bonds with enhanced visible-light photocatalytic performance
Authors: Wang Jian , Lin Wei , Hu Hao , Liu Chunxia , Cai Qiong , Zhou Shijian , Kong Yan
Published: January 2021

A Z-system hybrid of F-TiO2 quantum dots/g-C3N4 nanosheets with an effective pathway (C–O bond) for charge transfer and selective recombination was constructed.
Imidazol-5-ones as a substrate for [1,5]-hydride shift triggered cyclization
Authors: Zaitseva Elvira R. , Smirnov Alexander Yu. , Myasnyanko Ivan N. , Mineev Konstantin S. , Sokolov Anatolii I. , Volkhina Tatyana N. , Mikhaylov Andrey A. , Baleeva Nadezhda S. , Baranov Mikhail S.
Published: January 2021

(2-Aminobenzylidene)-imidazolones were used as substrates for [1,5]-hydride shift triggered cyclization under promotion by TiCl4 at room temperature.
Nonylbisoxazole-based donor–acceptor copolymers for polymer solar cells
Authors: Liu Bo , Chen Lang , Wang Xiaobo , Li Lang , Wang Gang
Published: January 2021

A new NBO-based polymer PBDFNBO was synthesized and applied to the field of polymer solar cells, and achieved a power conversion efficiency of 5.0% without any post-treatment.
Artificial enzymes bringing together computational design and directed evolution
Authors: Mariz Beatriz de Pina , Carvalho Sara , Batalha Iris L. , Pina Ana Sofia
Published: January 2021

This manuscript reviews the combination of computational enzyme design and directed evolution and its advantages in the development of artificial enzymes.
Aggregation-induced phosphorescence of an anthraquinone based emitter
Authors: Goudappagouda  , Nidhankar Aakash D. , Nayak Rashmi A. , Santhosh Babu Sukumaran
Published: January 2021

Room temperature phosphorescence (RTP) of metal-free organic molecules is a hot topic of current research interest. In this work, aggregation drives a weakly emissive anthraquinone derivative to exhibit room temperature phosphorescence.
Unique dual fluorescence emission in the solid state from a small molecule based on phenanthrocarbazole with an AIE luminogen as a single-molecule white-light emissive material
Authors: Chatsirisupachai Jirat , Nalaoh Phattananawee , Kaiyasuan Chokchai , Chasing Pongsakorn , Sudyoadsuk Taweesak , Promarak Vinich
Published: January 2021

New triphenylethylene-phenanthrocarbazole (PCTrPE) was the first small molecule that exhibited dual fluorescence emission in the solid state providing a new strategy to realize a single-molecule white emissive material for white OLEDs.
A co-dispersed nanosystem of strontium-anchored reduced graphene oxide to enhance the bioactivity and mechanical property of polymer scaffolds
Authors: Qi Fangwei , Wang Chen , Peng Shuping , Shuai Cijun , Yang Wenjing , Zhao Zhenyu
Published: January 2021

Poly(l-lactide) (PLLA) is a promising bone repair material owing to its good biocompatibility and natural degradability, but its lack of bioactivity and insufficient mechanical property restrict its further application.
NIR-triggered engineered photosynthetic micro–nanodevice for reversing the hypoxic tumor immunosuppressive microenvironment
Authors: Guo Mingming , Li Shuang , Peng Wenchang , Wang Shuchao , Zhang Xiao-Dong , Han Tie , Zheng Bin , Ming Dong
Published: January 2021

Hypoxia is an important feature of the tumor microenvironment, which seriously affects the immunotherapy of tumors.
A self-assembled tetrathiafulvalene box
Authors: Krykun Serhii , Croué Vincent , Alévêque Olivier , Levillain Eric , Allain Magali , Mézière Cécile , Carré Vincent , Aubriet Frédéric , Voïtenko Zoia , Goeb Sébastien , Sallé Marc
Published: January 2021

A M8L2metalla-cage constructed through coordination-driven self-assembly from a quinonato bis-ruthenium complex and an electron-rich tetrathiafulvalene (TTF) tetrapyridyl ligand is depicted.
A mild one-pot synthesis of 2-iminothiazolines from thioureas and 1-bromo-1-nitroalkenes
Authors: Xu Yuan , Ge Xin , Zhang Yuhan , Zhang Hongbin , Liu Xue-Wei
Published: January 2021

A mild method to access functionalized 2-iminothiazolines in a facile and efficient manner has been developed.
Sensitive impedimetric detection of troponin I with metal–organic framework composite electrode
Authors: Gupta Arushi , Sharma Sandeep Kumar , Pachauri Vivek , Ingebrandt Sven , Singh Suman , Sharma Amit L. , Deep Akash
Published: January 2021

A Cu-MOF/PANI modified screen-printed electrode based immunosensing technique is described for the sensitive detection of cardiac troponin I. The sensor provides detection over a wide concentration range with a limit of detection of 0.8 ng mL−1.
Implementation of the emulsification-diffusion method by solvent displacement for polystyrene nanoparticles prepared from recycled material
Authors: Pineda-Reyes Ana María , Hernández Delgado Mauricio , Zambrano-Zaragoza María de la Luz , Leyva-Gómez Gerardo , Mendoza-Muñoz Nestor , Quintanar-Guerrero David
Published: January 2021

A novel solvent emulsification-displacement method for obtaining polystyrene nanoparticles is reported. This process has an added value and can be an alternative for the recycling of expanded polystyrene.
Solid-phase reactive chromatography (SPRC): a sustainable method for the synthesis of benzimidazol-diphenyl-2-imino-thiazolidine-4-ols (hemiaminals) which are active against lung cancer
Authors: Bangade V. M. , Mali P. R. , Meshram H. M.
Published: January 2021

Synthesis of benzimidazol-diphenyl-2-imino-thiazolidine-4-ol (hemiaminal) by column chromatography.
Pharmacophore modeling and virtual screening studies for discovery of novel farnesoid X receptor (FXR) agonists
Authors: Zhao Shizhen , Peng Wenjing , Li Xinping , Wang Le , Yin Wenbo , Wang Yan-Dong , Hou Ruifang , Chen Wei-Dong
Published: January 2021

In this study, we have employed an integrated virtual screening by combining ligand-based pharmacophore mapping and molecular docking to identify novel nonsteroidal FXR agonists.
Preparation of Ni micropillar arrays with high aspect ratios using anodic porous alumina template and their application to molds for imprinting
Authors: Yanagishita Takashi , Hayakawa Tomohiro , Kondo Toshiaki , Masuda Hideki
Published: January 2021

Ni micropillar array with high aspect ratio prepared using anodic porous alumina.
Rapid and continuous fabrication of TiO2 nanoparticles encapsulated by polyimide fine particles using a multistep flow-system and their application
Authors: Ishizaka Takayuki , Chatterjee Maya , Kawanami Hajime
Published: January 2021

We rapidly and continuously fabricated TiO2 nanoparticles encapsulated by polymer fine particles, and the fabricated nanomaterials showed high UV shielding efficiency.
Ligand-enforced intimacy between a gold cation and a carbenium ion: impact on stability and reactivity
Authors: Litle Elishua D. , Wilkins Lewis C. , Gabbaï François P.
Published: January 2021

This work describes the synthesis of carbenium-based, γ-cationic phosphines and their coordination to Au(i) cations , leading to carbophilic catalysts whose activity is enhanced by the ligand-enforced convergence of the positively charged moieties.
Growth of gas-filled penny-shaped cracks in decompressed hydrogels
Authors: Zhang Yansheng , Etzold Merlin A. , Lefauve Adrien
Published: January 2021

We use CO2-saturated hydrogel beads to explain how the decompression of soft brittle materials can lead to the growth of large internal gas-filled cracks.
Inverse desert beetle-like ZIF-8/PAN composite nanofibrous membrane for highly efficient separation of oil-in-water emulsions
Authors: Li Haoyu , Mu Peng , Li Jian , Wang Qingtao
Published: January 2021

An inverse desert beetle-like ZIF-8/PAN membrane with the ability of “oil capture in water” can achieve oil-in-water emulsion separation.
Phosphorus-modified ruthenium–tellurium dendritic nanotubes outperform platinum for alkaline hydrogen evolution
Authors: Liu Min , Xu You , Liu Songliang , Yin Shuli , Liu Mengying , Wang Ziqiang , Li Xiaonian , Wang Liang , Wang Hongjing
Published: January 2021

Phosphorus-modified ruthenium–tellurium dendritic nanotubes were fabricated and demonstrated improved electrocatalytic performance for hydrogen evolution.
Two-dimensional metal–organic framework with perpendicular one-dimensional nano-channel as precise polysulfide sieves for highly efficient lithium–sulfur batteries
Authors: Chang Zhi , Qiao Yu , Wang Jie , Deng Han , Zhou Haoshen
Published: January 2021

When 2D CuBDC MOF sheets with perpendicular 1D nano-channels (5.2 Å) was were used as polysulfides sieves for Li–S batteries, suppressed “shuttle effect” and enhanced electrochemical performance were achieved.
A highly programmable platform for sequential release of protein therapeutics
Authors: Wang Haozheng , Liu Rui , Wang Sha , Guan Ying , Zhang Yongjun
Published: January 2021

A method for sequential release of protein therapeutics is developed which allows the proteins to be released at the right sequence and at the right time points.
Complying with the physiological functions of Golgi apparatus for secretory exocytosis facilitated oral absorption of protein drugs
Authors: Xing Liyun , Zheng Yaxian , Yu Yinglan , Wu Ruinan , Liu Xi , Zhou Rui , Huang Yuan
Published: January 2021

Intestinal epithelial cells are the primary biological barriers for orally administrated nano-formulations and the delivered protein drugs.
Synthesis of spirodithienogermole with triphenylamine units as a dopant-free hole-transporting material for perovskite solar cells
Authors: Ohshita Joji , Kondo Keisuke , Adachi Yohei , Song Myungkwan , Jin Sung-Ho
Published: January 2021

Spiro-condensed dithienogermoles with electron-donating aromatic substituents were prepared, one of which was examined as the hole-transporting material of perovskite solar cell, providing the maximal photo-current conversion efficiency of 14.67%.
Surface organic ligand-passivated quantum dots: toward high-performance light-emitting diodes with long lifetimes
Authors: Wang Lishuang , Lv Ying , Lin Jie , Zhao Jialong , Liu Xingyuan , Zeng Ruosheng , Wang Xun , Zou Bingsuo
Published: January 2021

Short thiol-based ligands (1-dodecanethiol (DDT) and 1-octanethiol (OT)) are used to investigate the surface organic ligand effect on device performance. The OT-QDs based QLED reach an improved overall charge balance in the LEDs and a long operational lifetime over 420 000 h.
The influence of NLTE effects in Fe I lines on an inverted atmosphere
Authors: Smitha H. N. , Holzreuter R. , van Noort M. , Solanki S. K.
Published: January 2021

Context. This paper forms the second part of our study of how neglecting non-local thermodynamic equilibrium (NLTE) conditions in the formation of Fe I 6301.5 Å and the 6302.5 Å lines affects the atmosphere that is obtained by inverting the Stokes profiles of these lines in LTE. The main cause of NLTE effects in these lines is the line opacity deficit that is due to the excess ionisation of Fe I atoms by ultraviolet (UV) photons in the Sun.

Aims. In the first paper, these photospheric lines were assumed to have formed in 1D NLTE and the effects of horizontal radiation transfer (RT) were neglected. In the present paper, the iron lines are computed by solving the RT in 3D. We investigate the effect of horizontal RT on the inverted atmosphere and how it can enhance or reduce the errors that are due to neglecting 1D NLTE effects.

Methods. The Stokes profiles of the iron lines were computed in LTE, 1D NLTE, and 3D NLTE. They were all inverted using an LTE inversion code. The atmosphere from the inversion of LTE profiles was taken as the reference model. The atmospheres from the inversion of 1D NLTE profiles (testmodel-1D) and 3D NLTE profiles (testmodel-3D) were compared with it. Differences between reference and testmodels were analysed and correspondingly attributed to NLTE and 3D effects.

Results. The effects of horizontal RT are evident in regions surrounded by strong horizontal temperature gradients. That is, along the granule boundaries, regions surrounding magnetic elements, and its boundaries with intergranular lanes. In some regions, the 3D effects enhance the 1D NLTE effects, and in some, they weaken these effects. In the small region analysed in this paper, the errors due to neglecting the 3D effects are lower than 5% in temperature. In most of the pixels, the errors are lower than 20% in both velocity and magnetic field strength. These errors also persist when the Stokes profiles are spatially and spectrally degraded to the resolution of the Swedish Solar Telescope (SST) or Daniel K. Inouye Solar Telescope (DKIST).

Conclusions. Neglecting horizontal RT introduces errors not only in the derived temperature, but also in other atmospheric parameters. The error sizes depend on the strength of the local horizontal temperature gradients. Compared to the 1D NLTE effect, the 3D effects are more localised in specific regions in the atmosphere and are weaker overall.
A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS
Authors: van Holstein R.G. , Stolker T. , Jensen-Clem R. , Ginski C. , Milli J. , de Boer J. , Girard J.H. , Wahhaj Z. , Bohn A.J. , Millar-Blanchaer M.A. , Benisty M. , Bonnefoy M. , Chauvin G. , Dominik C. , Hinkley S. , Keller C.U. , Keppler M. , Langlois M. , Marino S. , Ménard F. , Perrot C. , Schmidt T.O.B. , Vigan A. , Zurlo A. , Snik F.
Published: January 2021

Context. Young giant planets and brown dwarf companions emit near-infrared radiation that can be linearly polarized up to several percent. This polarization can reveal the presence of an (unresolved) circumsubstellar accretion disk, rotation-induced oblateness of the atmosphere, or an inhomogeneous distribution of atmospheric dust clouds.

Aims. We aim to measure the near-infrared linear polarization of 20 known directly imaged exoplanets and brown dwarf companions.

Methods. We observed the companions with the high-contrast imaging polarimeter SPHERE-IRDIS at the Very Large Telescope. We reduced the data using the IRDAP pipeline to correct for the instrumental polarization and crosstalk of the optical system with an absolute polarimetric accuracy <0.1% in the degree of polarization. We employed aperture photometry, angular differential imaging, and point-spread-function fitting to retrieve the polarization of the companions.

Results. We report the first detection of polarization originating from substellar companions, with a polarization of several tenths of a percent for DH Tau B and GSC 6214-210 B in H-band. By comparing the measured polarization with that of nearby stars, we find that the polarization is unlikely to be caused by interstellar dust. Because the companions have previously measured hydrogen emission lines and red colors, the polarization most likely originates from circumsubstellar disks. Through radiative transfer modeling, we constrain the position angles of the disks and find that the disks must have high inclinations. For the 18 other companions, we do not detect significant polarization and place subpercent upper limits on their degree of polarization. We also present images of the circumstellar disks of DH Tau, GQ Lup, PDS 70, β Pic, and HD 106906. We detect a highly asymmetric disk around GQ Lup and find evidence for multiple scattering in the disk of PDS 70. Both disks show spiral-like features that are potentially induced by GQ Lup B and PDS 70 b, respectively.

Conclusions. The presence of the disks around DH Tau B and GSC 6214-210 B as well as the misalignment of the disk of DH Tau B with the disk around its primary star suggest in situ formation of the companions. The non-detections of polarization for the other companions may indicate the absence of circumsubstellar disks, a slow rotation rate of young companions, the upper atmospheres containing primarily submicron-sized dust grains, and/or limited cloud inhomogeneity.
Massive heartbeat stars from TESS
Authors: Kołaczek-Szymański P. A. , Pigulski A. , Michalska G. , Moździerski D. , Różański T.
Published: January 2021

Context. Heartbeat stars are eccentric binaries that exhibit a characteristic shape of brightness changes close to the periastron passage, primarily caused by a variable tidal distortion of the components. Variable tidal potential can drive tidally excited oscillations (TEOs), which are usually gravity modes. Studies of heartbeat stars and TEOs open up new possibilities for probing the interiors of massive stars. There are only a few massive (masses of components ≳2 M⊙) systems of this type that are known thus far.

Aims. Using TESS data from the first 16 sectors, we searched for new massive heartbeat stars and TEOs using a sample of over 300 eccentric spectroscopic binaries.

Methods. We analysed 2 min and 30 min cadence TESS data. Then we fitted Kumar’s analytical model to the light curves of stars showing heartbeats and performed a times-series analysis of the residuals searching for TEOs and periodic intrinsic variability.

Results. We found 20 massive heartbeat systems, of which 7 exhibit TEOs. The TEOs occur at harmonics of orbital frequencies in the range between 3 and 36, with the median value equal to 9, which is lower than those in known Kepler systems with TEOs. The most massive system in this sample is the quadruple star HD 5980, a member of the Small Magellanic Cloud. With a total mass of ∼150 M⊙ it is the most massive system showing a heartbeat. Six stars in the sample of the new heartbeat stars are eclipsing. A comparison of the parameters derived from fitting Kumar’s model and from light-curve modelling shows that Kumar’s model does not provide reliable parameters. In other words, the orbital parameters can be reliably derived from fitting heartbeat light curves only if the model includes all proximity effects. Finally, intrinsic pulsations of β Cep, SPB, δ Sct, and γ Dor-type were found in nine heartbeat systems. This opens an interesting possibility for studies of pulsation-binarity interaction and the co-existence of forced and self-excited oscillations.
The polarization-encoded self-coherent camera
Authors: Bos S. P.
Published: January 2021

Context. The exploration of circumstellar environments by means of direct imaging to search for Earth-like exoplanets is one of the challenges of modern astronomy. One of the current limitations are evolving non-common path aberrations (NCPA) that originate from optics downstream of the main wavefront sensor. Measuring these NCPA with the science camera during observations is the preferred solution for minimizing the non-common path and maximizing the science duty cycle. The self-coherent camera (SCC) is an integrated coronagraph and focal-plane wavefront sensor that generates wavefront information-encoding Fizeau fringes in the focal plane by adding a reference hole (RH) in the Lyot stop. However, the RH is located at least 1.5 pupil diameters away from the pupil center, which requires the system to have large optic sizes and results in low photon fluxes in the RH.

Aims. Here, we aim to show that by featuring a polarizer in the RH and adding a polarizing beamsplitter downstream of the Lyot stop, the RH can be placed right next to the pupil. This greatly increases the photon flux in the RH and relaxes the requirements on the optics size due to a smaller beam footprint. We refer to this new variant of the SCC as the polarization-encoded self-coherent camera (PESCC).

Methods. We study the performance of the PESCC analytically and numerically, and compare it, where relevant, to the SCC. We look into the specific noise sources that are relevant for the PESCC and quantify their effect on wavefront sensing and control (WFSC).

Results. We show analytically that the PESCC relaxes the requirements on the focal-plane sampling and spectral resolution with respect to the SCC by a factor of 2 and 3.5, respectively. Furthermore, we find via our numerical simulations that the PESCC has effectively access to ∼16 times more photons, which improves the sensitivity of the wavefront sensing by a factor of ∼4. We identify the need for the parameters related to the instrumental polarization and differential aberrations between the beams to be tightly controlled – otherwise, they limit the instrument’s performance. We also show that without additional measurements, the RH point-spread function (PSF) can be calibrated using PESCC images, enabling coherent differential imaging (CDI) as a contrast-enhancing post-processing technique for every observation. In idealized simulations (clear aperture, charge two vortex coronagraph, perfect DM, no noise sources other than phase and amplitude aberrations) and in circumstances similar to those of space-based systems, we show that WFSC combined with CDI can achieve a 1σ raw contrast of ∼3 × 10−11 − 8 × 10−11 between 1 and 18 λ/D.

Conclusions. The PESCC is a powerful, new focal-plane wavefront sensor that can be relatively easily integrated into existing ground-based and future space-based high-contrast imaging instruments.
The prebiotic molecular inventory of Serpens SMM1
Authors: Ligterink N. F. W. , Ahmadi A. , Coutens A. , Tychoniec Ł. , Calcutt H. , van Dishoeck E. F. , Linnartz H. , Jørgensen J. K. , Garrod R. T. , Bouwman J.
Published: January 2021

Aims. Methyl isocyanate (CH3NCO) and glycolonitrile (HOCH2CN) are isomers and prebiotic molecules that are involved in the formation of peptide structures and the nucleobase adenine, respectively. These two species are investigated to study the interstellar chemistry of cyanides (CN) and isocyanates (NCO) and to gain insight into the reservoir of interstellar prebiotic molecules.

Methods. ALMA observations of the intermediate-mass Class 0 protostar Serpens SMM1-a and ALMA-PILS data of the low-mass Class 0 protostar IRAS 16293B are used. Spectra are analysed with the CASSIS line analysis software package in order to identify and characterise molecules.

Results. CH3NCO, HOCH2CN, and various other molecules are detected towards SMM1-a. HOCH2CN is identified in the PILS data towards IRAS 16293B in a spectrum extracted at a half-beam offset position from the peak continuum. CH3NCO and HOCH2CN are equally abundant in SMM1-a at [X]/[CH3OH] of 5.3 × 10−4 and 6.2 × 10−4, respectively. A comparison between SMM1-a and IRAS 16293B shows that HOCH2CN and HNCO are more abundant in the former source, but CH3NCO abundances do not differ significantly. Data from other sources are used to show that the [CH3NCO]/[HNCO] ratio is similar in all these sources within ~10%.

Conclusions. The new detections of CH3NCO and HOCH2CN are additional evidence for a large interstellar reservoir of prebiotic molecules that can contribute to the formation of biomolecules on planets. The equal abundances of these molecules in SMM1-a indicate that their formation is driven by kinetic processes instead of thermodynamic equilibrium, which would drive the chemistry to one product. HOCH2CN is found to be much more abundant in SMM1-a than in IRAS 16293B. From the observational data, it is difficult to indicate a formation pathway for HOCH2CN, but the thermal Strecker-like reaction of CN− with H2CO is a possibility. The similar [CH3NCO]/[HNCO] ratios found in the available sample of studied interstellar sources indicate that these two species are either chemically related or their formation is affected by physical conditions in the same way. Both species likely form early during star formation, presumably via ice mantle reactions taking place in the dark cloud or when ice mantles are being heated in the hot core. The relatively high abundances of HOCH2CN and HNCO in SMM1-a may be explained by a prolonged stage of relatively warm ice mantles, where thermal and energetic processing of HCN in the ice results in the efficient formation of both species.
Semianalytical model for planetary resonances
Authors: Gallardo Tabaré , Beaugé Cristián , Giuppone Cristian A.
Published: January 2021

Context. Planetary resonances are a common dynamical mechanism acting on planetary systems. However, no general model for describing their properties exists, particularly for commensurabilities of any order and arbitrary eccentricity and inclination values.

Aims. We present a semianalytical model that describes the resonance strength, width, location and stability of fixed points, and periods of small-amplitude librations. The model is valid for any two gravitationally interacting massive bodies, and is thus applicable to planets around single or binary stars.

Methods. Using a theoretical framework in the Poincaré and Jacobi reference system, we developed a semianalytical method that employs a numerical evaluation of the averaged resonant disturbing function. Validations of the model are presented that compare its predictions with dynamical maps for real and fictitious systems.

Results. The model describes many dynamical features of planetary resonances very well. Notwithstanding the good agreement found in all cases, a small deviation is noted in the location of the resonance centers for circumbinary systems. As a consequence of its application to the HD 31527 system, we found that the updated best-fit solution leads to a high-eccentricity stable libration between the middle and outer planets inside the 16/3 mean-motion resonance (MMR). This is the first planetary system whose long-term dynamics appears dominated by such a high-order commensurability. In the case of circumbinary planets, the overlap of N/1 mean-motion resonances coincides very well with the size of the global chaotic region close to the binary, as well as its dependence on the mutual inclination.
Illumination of the accretion disk in black hole binaries: An extended jet as the primary source of hard X-rays
Authors: Reig P. , Kylafis N. D.
Published: January 2021

Context.The models that seek to explain the reflection spectrum in black hole binaries usually invoke a point-like primary source of hard X-rays. This source illuminates the accretion disk and gives rise to the discrete (lines) and continuum-reflected components.

Aims.The main goal of this work is to investigate whether the extended, mildly relativistic jet that is present in black hole binaries in the hard and hard-intermediate states is the hard X-ray source that illuminates the accretion disk.

Methods.We use a Monte Carlo code that simulates the process of inverse Compton scattering in a mildly relativistic jet rather than in a “corona” of some sort. Blackbody photons from the thin accretion disk are injected at the base of the jet and interact with the energetic electrons that move outward with a bulk velocity that is a significant fraction of the speed of light.

Results.Despite the fact that the jet moves away from the disk at a mildly relativistic speed, we find that approximately 15−20% of the input soft photons are scattered, after Comptonization, back toward the accretion disk. The vast majority of the Comptonized, back-scattered photons escape very close to the black hole (h ≲ 6 rg, wherergis the gravitational radius), but a non-negligible amount escape at a wide range of heights. At high heights,h ∼ 500−2000 rg, the distribution falls off rapidly. The high-height cutoff strongly depends on the width of the jet at its base and is almost insensitive to the optical depth. The disk illumination spectrum is softer than the direct jet spectrum of the radiation that escapes in directions that do not encounter the disk.

Conclusions.We conclude that an extended jet is an excellent candidate source of hard photons in reflection models.
Study on the Method of Identifying Ultrafine Bubbles Using Ultrasound under the Presence of Solid Nanoparticles
Authors: Yamawaki Naoya , Okumura Hayato , Akamatsu Shigenori , Nishiuchi Yusuke , Hata Takashi
Published: January 2021

The method of making OH radicals generated by the collapse of ultrafine bubbles as an indicator when applying ultrasound was examined as the method of identifying ultrafine bubbles less than 1 μm in diameter under the presence of mixed solid nanoparticles. First, potassium iodide (KI) method was used to evaluate OH radicals. Since difference in absorbance due to OH radicals generated by the collapse of ultrafine bubbles is very small when using air as contained gas, evaluation using the KI method was difficult; however, a distinct difference in absorbance was confirmed by increasing the amount of OH radicals generated by using ozone as contained gas. Moreover, the higher the ultrasound frequency, the greater the difference in absorbance. On the other hand, a luminescence phenomenon related to the collapse of ultrafine bubbles by ultrasound was confirmed with sonoluminescence observation, confirming further that the luminescence intensity of water added with solid particles of the same diameter and number density as those of ultrafine bubbles is smaller than that of ultrafine bubble water.
Flow Characteristics of Drag-Reducing Surfactant Solutions
Authors: Saeki Takashi , Kaide Aya
Published: January 2021

The objective of this study is to clarify the flow characteristics of drag-reducing flow and to elucidate the mechanism underlying this phenomenon. The surfactant and counter ion we used were Lipothoquad O/12 and sodium salicylate, respectively. The drag reduction rate (DR%) was measured by using a recirculating system with a diameter of 25.6 mm. We also measured the flow characteristics of the surfactant solutions with different concentrations and temperatures by using particle image velocimetry (PIV). From the experimental results, DR% at an average velocity of 2.0 m/s increased from 0 to 68% as the temperature increased from 10 to 40 °C at a constant concentration of surfactant (300 mg/L). From the velocity contour plot obtained from PIV, we found that the thickness of the lower-velocity region of the drag-reducing flow near the pipe wall was thick at 20 °C, whereas vortex motions seemed controlled at 30 °C. On the other hand, the lower-velocity region thickened as the concentration of the surfactant increased at 25°C. Even if the same level of drag-reducing effects occurred, the flow patterns were quite different depending on the concentration and temperature.
Preparation and Rheology of Magnetorheological Fluid Using Six Kinds of Fumed Silica as Stabilizing Additives
Authors: Kanda Makoto , Kaide Aya , Saeki Takashi , Tochigi Hiroshi
Published: January 2021

In this study, magnetorheological fluid (MRF) was prepared with several kinds of hydrophobic fumed silica in order to improve MRF stability while maintaining desirable fluidity. We conducted steady flow measurements and oil separation tests under gravity and centrifugal conditions. The linkage of fumed silica particles was also observed morphologically by transmission electron microscopy. We found that the MRF sedimentation stability correlated with viscosity in the lower shear rate range. The oil separation ratio improved with the addition of the fumed silicas examined in this study. The surface characteristics of the silica particles affected the stabilization ability. The addition of hydrophobic fumed silica can desirably increase MRF magnetic properties.
Observation of Pseudo Plume Behavior by Hydrate Sedimentary Layer Decomposition
Authors: Takahashi Yusuke , Ezure Ryosuke , Takano Shun , Komatsu Hiroyuki , Yamagiwa Kazuaki , Tajima Hideo
Published: January 2021

We are focusing on the practical use of methane hydrate. For recovery and use of it as an energy resource, it is necessary to consider the possibility of clogging in the recovery pipe due to the rehydration of bubbles. The purpose of this research was to observe experimentally and evaluate theoretically the decomposition behavior of hydrate sedimentary layer and the rising behavior of bubbles generated by hydrate decomposition. Chlorodifluoromethane was used as a low pressure model gas of methane. Hydrate sedimentary layer was produced by cooling and pressurizing water in countercurrent contact with gas using a hydrate formation recovery device. The recovered hydrate was decomposed by the heating or depressurization method, without flowing water. Two theoretical rising velocities were derived from the theoretical value with using the Navier-Stokes equation or the values in consideration of the bubble shape and hydrate film existence. The experimental rising velocities of small spherical bubbles radius agreed well with the theoretical value by the Navier-Stokes equation. The relatively large elliptical bubbles showed a behavior close to the theoretical value of bubble with hydrate film. Under the pressure and temperature conditions closer to the hydrate equilibrium line, almost no generated bubbles could be identified visually.
Study on the Effects of Grinding Factor and Scaling up in Grinding Using Horizontal Dry Bead Mill
Authors: Tamura Takahiro , Kimata Mitsumasa
Published: January 2021

Effect of grinding factor and scaling up were carried out by grinding using horizontal dry bead mill. For the experiments, 2 sizes of horizontal dry bead mills with different capacities, lab and manufacturing scale, were used to study scaling up and down. The grinding experiments were performed by changing each typical grinding factor for bead mills, including the agitator peripheral speed, bead packing density, bead diameter, and material feeding speed. This set of experiments was conducted for 3 kinds of materials, silica sand of natural inorganic materials, alumina of synthetic inorganic materials, and activated carbon of organic materials. As a result, common for all materials, similar rules were found between the particle size and specific energy, the amount of mechanical energy per unit amount of material. In addition, these rules were applicable for the different-size mills, indicating that the scale can be controlled by the rules and specific energy. Also, it is revealed that when using a single type of material, changing the bead diameter changes the energy efficiency, indicating that using small-diameter bead was effective for efficient grinding.