bluuebunny/crossref_metadata_2025 huggingface dataset:
Event-driven proto-object based saliency in 3D space to attract a robot’s attention
Authors: Ghosh Suman , D’Angelo Giulia , Glover Arren , Iacono Massimiliano , Niebur Ernst , Bartolozzi Chiara
Published: May 2022

To interact with its environment, a robot working in 3D space needs to organise its visual input in terms of objects or their perceptual precursors, proto-objects. Among other visual cues, depth is a submodality used to direct attention to visual features and objects. Current depth-based proto-object attention models have been implemented for standard RGB-D cameras that produce synchronous frames. In contrast, event cameras are neuromorphic sensors that loosely mimic the function of the human retina by asynchronously encoding per-pixel brightness changes at very high temporal resolution, thereby providing advantages like high dynamic range, efficiency (thanks to their high degree of signal compression), and low latency. We propose a bio-inspired bottom-up attention model that exploits event-driven sensing to generate depth-based saliency maps that allow a robot to interact with complex visual input. We use event-cameras mounted in the eyes of the iCub humanoid robot to directly extract edge, disparity and motion information. Real-world experiments demonstrate that our system robustly selects salient objects near the robot in the presence of clutter and dynamic scene changes, for the benefit of downstream applications like object segmentation, tracking and robot interaction with external objects.
Epidemiology of accelerometer-based sleep parameters in US school-aged children and adults: NHANES 2011–2014
Authors: Su Shaoyong , Li Xinyue , Xu Yanyan , McCall William V. , Wang Xiaoling
Published: May 2022

We aimed to provide objectively measured sleep parameters across lifespan by sex and race in a national representative sample of US population. The study included 11,279 participants 6 years and older from the National Health and Nutrition Examination Survey (NHANES) 2011–2014, who had at least 3 days of valid sleep parameters calculated from 7-day 24-h accelerometer recording. Sleep duration showed a U-shaped association with age and reached the minimum at age 40 and started to increase again around age 50. The clock time for sleep onset (CTSO) delayed with age and reached the maximum at about age 20. CTSO then advanced until age 50, leveled off until age 70, then advanced again after age 70. Sleep efficiency showed an overall decreasing trend across the lifespan but stabilized from age 30 to about age 60. US young adults in age 20 s are the ones who slept at the latest around midnight, while the middle aged US residents between 40 and 50 years old slept the least. Females generally present longer sleep duration than males, while more likely to have later sleep onset, particularly at older ages. Non-Hispanic Blacks showed worse sleep characteristics, i.e. sleep later, sleep shorter, and sleep less efficiently, compared to other racial groups. In conclusion, this study provides valuable insights on the characteristics of sleep habits of residents of the United States by using objectively measurements of sleep parameters and will help guide personalized advice on sleep hygiene.
Pervasive male-biased expression throughout the germline-specific regions of the sea lamprey genome supports key roles in sex differentiation and spermatogenesis
Authors: Yasmin Tamanna , Grayson Phil , Docker Margaret F. , Good Sara V.
Published: May 2022

Sea lamprey undergo programmed genome rearrangement (PGR) in which ∼20% of the genome is jettisoned from somatic cells during embryogenesis. Although the role of PGR in embryonic development has been studied, the role of the germline-specific region (GSR) in gonad development is unknown. We analysed RNA-sequence data from 28 sea lamprey gonads sampled across life-history stages, generated a genome-guided de novo superTranscriptome with annotations, and identified germline-specific genes (GSGs). Overall, we identified 638 GSGs that are enriched for reproductive processes and exhibit 36x greater odds of being expressed in testes than ovaries. Next, while 55% of the GSGs have putative somatic paralogs, the somatic paralogs are not differentially expressed between sexes. Further, putative orthologs of some the male-biased GSGs have known functions in sex determination or differentiation in other vertebrates. We conclude that the GSR of sea lamprey plays an important role in testicular differentiation and potentially sex determination.
Infiltrating natural killer cells bind, lyse and increase chemotherapy efficacy in glioblastoma stem-like tumorospheres
Authors: Breznik Barbara , Ko Meng-Wei , Tse Christopher , Chen Po-Chun , Senjor Emanuela , Majc Bernarda , Habič Anamarija , Angelillis Nicolas , Novak Metka , Župunski Vera , Mlakar Jernej , Nathanson David , Jewett Anahid
Published: May 2022

Glioblastomas remain the most lethal primary brain tumors. Natural killer (NK) cell-based therapy is a promising immunotherapeutic strategy in the treatment of glioblastomas, since these cells can select and lyse therapy-resistant glioblastoma stem-like cells (GSLCs). Immunotherapy with super-charged NK cells has a potential as antitumor approach since we found their efficiency to kill patient-derived GSLCs in 2D and 3D models, potentially reversing the immunosuppression also seen in the patients. In addition to their potent cytotoxicity, NK cells secrete IFN-γ, upregulate GSLC surface expression of CD54 and MHC class I and increase sensitivity of GSLCs to chemotherapeutic drugs. Moreover, NK cell localization in peri-vascular regions in glioblastoma tissues and their close contact with GSLCs in tumorospheres suggests their ability to infiltrate glioblastoma tumors and target GSLCs. Due to GSLC heterogeneity and plasticity in regards to their stage of differentiation personalized immunotherapeutic strategies should be designed to effectively target glioblastomas.
The dynamical complexity of seasonal soundscapes is governed by fish chorusing
Authors: Siddagangaiah Shashidhar , Chen Chi-Fang , Hu Wei-Chun , Farina Almo
Published: May 2022

Passive acoustic monitoring technology can depict underwater soundscapes, yet phenological and seasonal patterns and shifts in soundscapes are still poorly understood. Here we analyse the seasonal soundscape in the Eastern Taiwan Strait in 2017 using nonlinear dynamical complexity modelling. We find an annual phenology of fish chorusing that begins in spring, and peaks in summer before beginning to subside in autumn and becoming silent in winter. During spring and summer, the soundscape exhibited significantly higher complexity and predictability than in autumn and winter, due to the presence of regular fish chorusing. Soundscape dynamics shifted from being nonlinear in spring and summer to being linear and stochastic in autumn and winter. Our findings suggest that soundscapes could be used to measure phenological patterns and seasonal shifts in marine species behaviour. We propose that monitoring soundscapes could help assess the long-term health of marine ecosystems under environmental and climatic change.
Molecule-like and lattice vibrations in metal clusters
Authors: Ramankutty Krishnadas Kumaranchira , Yang Huayan , Baghdasaryan Ani , Teyssier Jeremie , Nicu Valentin Paul , Buergi Thomas
Published: May 2022

Low frequency Raman spectra of a series of atomically precise gold, silver and alloy clusters are presented. The spectra are characteristic for each cluster and show a systematic change upon alloying.
Dual doping with cations and anions for enhancing the structural stability of the sodium-ion layered cathode
Authors: Min Kyoungmin
Published: May 2022

Structural stability improvement by cation and anion dual doping.
A polypropylene (PP) supported solid polymer electrolyte enables high-stability organic lithium batteries at low temperature
Authors: Deng Wenwen , Shi Weibo , Wang Shuchan , Yan Zehua , Rui Zhen , Wang Qingling , Li Chang Ming
Published: May 2022

Sandwich-like solid polymer electrolytes (SPEs) were fabricated by using polypropylene (PP) separator as a substrate and PEO-LiTFSI-SN as a paste on both surfaces. A PTO||SPEs||Li battery was fabricated and showed high performance under low temperatures.
Versatile polyphenolic platforms in regulating cell biology
Authors: Cao Huan , Yang Lei , Tian Rong , Wu Haoxing , Gu Zhipeng , Li Yiwen
Published: May 2022

This review summarizes the recent advances in biointerfacial engineering using polyphenolic platforms, highlighting the relationship between material properties and cell biology regulationviacell–material contact and non-contact modes.
In silico COSMO-RS predictive screening of ionic liquids for the dissolution of plastic
Authors: Mohan Mood , Keasling Jay D. , Simmons Blake A. , Singh Seema
Published: May 2022

Herein we report the screening of 9405 ionic liquids for plastic dissolution using the continuum solvation model (COMSO-RS) and the results are validated with experiments.
Reconfigurable carrier type and photodetection of MoTe2 of various thicknesses by deep ultraviolet light illumination
Authors: Ko Byung Min , Khan Muhammad Farooq , Dastgeer Ghulam , Han Gyu Nam , Khan Muhammad Asghar , Eom Jonghwa
Published: May 2022

We have modulated the Fermi level of MoTe2 by deep ultraviolet light (a wavelength of 220 nm) illumination in different gaseous environments.
Teaching stereoisomers through gesture, action, and mental imagery
Authors: Ping Raedy , Parrill Fey , Church Ruth Breckinridge , Goldin-Meadow Susan
Published: May 2022

Many undergraduate chemistry students struggle to understand the concept of stereoisomers, molecules that have the same molecular formula and sequence of bonded atoms but are different in how their atoms are oriented in space. Our goal in this study is to improve stereoisomer instruction by getting participants actively involved in the lesson. Using a pretest–instruction–posttest design, we instructed participants to enact molecule rotation in three ways: (1) by imagining the molecules’ movements, (2) by physically moving models of the molecules, or (3) by gesturing the molecules’ movements. Because gender differences have been found in students’ performance in chemistry (Moss-Racusin et al., 2018), we also disaggregated our effects by gender and examined how men and women responded to each of our 3 types of instruction. Undergraduate students took a pretest on stereoisomers, were randomly assigned to one of the 3 types of instruction in stereoisomers, and then took a posttest. We found that, controlling for pretest performance, both women and men participants made robust improvements after instruction. We end with a discussion of how these findings might inform stereoisomer instruction.
Self-forming double-crosslinked hydrogels by the marriage of catechols and enzyme mimetic polymers
Authors: Chen Yaqing , Misselwitz Erik , Agergaard Asger Holm , Andersen Amanda , Pedersen Carsten , Birkedal Henrik
Published: May 2022

Double crosslinked hydrogels are formed by having one network component catalyze the crosslinking of the other in a bioinspired manner.
An (NH4)2S2O8-promoted cross-coupling of thiols/diselenides and sulfoxides for the synthesis of unsymmetrical disulfides/selenosulfides
Authors: Ma Yang-Tong , Lin Chao , Huang Xiao-Bo , Liu Miao-Chang , Zhou Yun-Bing , Wu Hua-Yue
Published: May 2022

An (NH4)2S2O8-promoted cross-coupling of thiols/diselenides and sulfoxides to construct unsymmetrical disulfides/selenosulfides is disclosed.
Water-soluble AIE-active fluorescent organic nanoparticles for ratiometric detection of SO2 in the mitochondria of living cells
Authors: Feng Gai-li , Liu Yi-chen , Ji Yan-ming , Zhou Wei , Li Xia-fen , Hou Min , Gao Jie-lei , Zhang Yuan , Xing Guo-wen
Published: May 2022

Mitochondria-targeted fluorescent organic nanoparticles (TYDLs) with a low detection limit (75 nM) were reported for the ratiometric detection of SO2/HSO3−in vitro and in vivo.
Copper-catalyzed hydroaminocarbonylation of benzylidenecyclopropanes: synthesis of γ,δ-unsaturated amides
Authors: Geng Hui-Qing , Wu Xiao-Feng
Published: May 2022

Herein, we have developed a copper-catalyzed hydroaminocarbonylation of benzylidenecyclopropanes under relatively mild conditions.
Growth rate and morphology study of tetrahydrofuran hydrate single crystals and the effect of salt
Authors: Ismail Nur Aminatulmimi , Koh Carolyn A.
Published: May 2022

Single crystals of sII THF hydrate grown using a seed/template method demonstrated an increase in growth rates. With 3.5 wt% NaCl, the growth rates are lower, resulting in a morphology of parallel intergrowths of octahedral crystals.
First-order hyperpolarizabilities of propellanes: elucidating structure–property relationships
Authors: Krajewski Bartosz , Rajput Swati Singh , Chołuj Marta , Wojaczyńska Elżbieta , Miniewicz Andrzej , Alam Md. Mehboob , Zaleśny Robert
Published: May 2022

In this study we aim to investigate, employing electronic and vibrational-structure theories, “structure–first hyperpolarizability” relationships for a series of 16 propellanes presenting a wide palette of substituents with varying electron-accepting/donating capabilities.
Highly sensitive and low-power consumption metalloporphyrin-based junctions for COx detection with excellent recovery
Authors: Ostovan Azar , Papior Nick , Naghavi S. Shahab
Published: May 2022

The development of cost-effective and eco-friendly sensor materials is needed to realize the application of detectors in daily life—such as in the internet of things.
The reaction between HgBr and O3: kinetic study and atmospheric implications
Authors: Gómez Martín Juan Carlos , Lewis Thomas R. , Douglas Kevin M. , Blitz Mark A. , Saiz-Lopez Alfonso , Plane John M. C.
Published: May 2022

We have carried out the first kinetic study of the reaction between HgBr and O3 using the PLP-LIF technique. Our results show that this reaction is the main atmospheric fate of the HgBr radical.
Infrared spectroscopy and theoretical structure analyses of protonated fluoroalcohol clusters: the impact of fluorination on the hydrogen bond networks
Authors: Shinkai Takahiro , Hsu Po-Jen , Fujii Asuka , Kuo Jer-Lai
Published: May 2022

Fluorine substitution of alkylalcohols strictly inhibits cyclic hydrogen bond structure formation of their protonated clusters.
Quantum-coupled borophene-based heterolayers for excitonic and molecular sensing applications
Authors: Vishwakarma Kavita , Rani Shivani , Chahal Sumit , Lu Chia-Yen , Ray Soumya Jyoti , Yang Chan-Shan , Kumar Prashant
Published: May 2022

STM and CAFM have been employed to detect coupling quantum states in borophene-based heterolayers and DFT calculations support it.
Monochromatic light-enhanced photocatalytic CO2 reduction based on exciton properties of two-dimensional lead halide perovskites
Authors: Xu Shengqi , Yang Lu , Wei Yixuan , Jia Yiming , Hu Meiqi , Bai Lianxia , Zhang Junzheng , Li Xinxin , Wei Shuo , Lu Jun
Published: May 2022

A series of 2D layered perovskites were used for photocatalytic CO2 reduction with a CO/CH4 yield of 158.69/6.9 μmol g−1 h−1. The monochromatic light matching their exciton absorption enhanced the yield by 1.27 times, compared with the full spectrum.
Guest-induced magnetic exchange in paramagnetic [M2L4]4+ coordination cages
Authors: Singh Mukesh K. , Etcheverry-Berríos Alvaro , Vallejo Julia , Sanz Sergio , Martínez-Lillo José , Nichol Gary S. , Lusby Paul J. , Brechin Euan K.
Published: May 2022

Encapsulation of a [ReBr6]2− guest in a [Cu2L4]4+ cage induces a magnetic interaction between the CuII and ReIV ions.
Towards the sustainable synthesis of microporous and layered titanosilicates: mechanochemical pre-treatment reduces the water amount
Authors: Santos-Vieira Isabel C. M. S. , Lin Zhi , Rocha João
Published: May 2022

Mechanosynthesis enables the preparation of microporous (and layered) titanosilicates by a process that is more sustainable than the conventional hydrothermal synthesis and is also amenable for upscaling.
Waste-to-wealth transition: application of natural waste materials as sustainable catalysts in multicomponent reactions
Authors: Kheilkordi Zohreh , Mohammadi Ziarani Ghodsi , Mohajer Fatemeh , Badiei Alireza , Varma Rajender S.
Published: May 2022

Application of natural waste materials as sustainable catalysts in multicomponent reactions.
Elucidating the role of reactive nitrogen intermediates in hetero-cyclization during hydrothermal liquefaction of food waste
Authors: LeClerc Heather O. , Atwi Rasha , Niles Sydney F. , McKenna Amy M. , Timko Michael T. , West Richard H. , Teixeira Andrew R.
Published: May 2022

Understanding the fate of nitrogen in food waste hydrothermal liquefaction.
A graphene oxide scaffold-encapsulated microcapsule for polysulfide-immobilized long life lithium–sulfur batteries
Authors: Lin Xirong , Yang Chaoyu , Han Tianli , Li Jinjin , Chen Zhonghua , Zhang Haikuo , Mu Kai , Si Ting , Liu Jinyun
Published: May 2022

A three-dimensional graphene oxide scaffold/sulfur composite-encapsulated microcapsule for lithium–sulfur batteries is developed through a microfluidic approach, which displays high electrochemical performance.
Electrospun polyacrylonitrile/hydroxyapatite composite nanofibrous membranes for the removal of lead ions from aqueous solutions
Authors: Feng Tao , Fan Zhixuan , Wu Si , Chen Lei , Tian Zishun
Published: May 2022

Renewable electrospun PAN/HAP membranes with a nanofiber–nanoparticle structure were fabricated for the efficient removal of lead ions from aqueous solutions.
Enhanced acetic acid sensing of MOF-derived α-Fe2O3/ZrO2 arising from phase junction and defects
Authors: Xie Dan , Zhang Feng , Dai Guoliang , Mao Zhu , Yu Kai , Qu Fengyu
Published: May 2022

The coexistence of phase junction, heterojunction and defects allows α-Fe2O3/ZrO2 to display an significant response towards acetic acid.
The fabrication of a highly electroactive chiral-interface self-assembled Cu(ii)-coordinated binary-polysaccharide composite for the differential pulse voltammetry (DPV) detection of tryptophan isomers
Authors: Du Yongxin , Mo Zunli , Pei Hebing , Liu Wentong , Yue Ruimei , Wang Xinran
Published: May 2022

It is of significance to fabricate excellently performing chiral carbon nanocomposites for chiral electrochemical detection applications.
Histidine functionalized MIL-53(Al) for lead(ii) removal from aqueous solution
Authors: Li Jipeng , Sun Yanzhi , Chen Yongmei , Tang Yang , Pan Junqing , Wan Pingyu
Published: May 2022

Introduction of histidine as a new modified material in MIL-53(Al) to enhance the adsorption properties for Pb(ii).
Highly diastereoselective synthesis of benzothiazolo[3,2-a]pyridines via [4 + 2] annulation reaction of 2-vinylbenzothiazoles and azlactones
Authors: Pan Bin , Li Ao , Liu Dong , Ni QingShan , Liang Wu , Du Fei , Gu Jing , Ouyang Qin
Published: May 2022

An highly diastereoselective AgOTf-catalyzed [4 + 2] annulation reaction of 2-vinylbenzothiazoles and azlactones was developed in good to excellent yields.
Is It Okay to Use Compressed NU-6 Files for Clinical Word Recognition Testing?
Authors: Mueller H. Gustav , Rokuson Jodi , Ricketts Todd , Dietrich Mary S. , Hornsby Benjamin W. Y.
Published: May 2022

Purpose:

The purpose of this study was to evaluate the impact of file compression on clinically measured word recognition scores obtained using the Northwestern University Test Number Six (NU-6; Auditec recording) materials.

Method:

Participants were 86 adults (
N
= 170 ears;
M
age
= 65.5). The 25 most difficult words from each of four NU-6 test lists were used to measure word recognition. Two lists were compressed using a freely available Advanced Audio Coding compression algorithm and two were not. Word recognition was measured in each ear using one compressed file and one uncompressed file. Percent correct scores were calculated in each test condition and log transformed for analyses. Clinically meaningful differences between uncompressed and compressed scores were examined using 95% critical difference ranges. The effects of file compression on word recognition scores were examined in the context of multiple potential confounding effects, including age and degree of hearing loss, using linear mixed-effects models (LMMs).

Results:

Differences between compressed and uncompressed scores in a given ear exceeded the 95% critical difference range in about 7% of cases, approximating the 5% of expected cases occurring due to chance. Likewise, LMM results revealed no significant effect of file compression on clinically measured NU-6 word recognition scores and no significant interactions between compression effects and age or degree of hearing loss.

Conclusions:

While the original uncompressed audio files are clearly the most appropriate stimuli for clinical purposes, our study results suggest that file compression, even at an aggressive 64 kilobits per second, does not have a statistically significant, or clinically meaningful, effect on word recognition scores when measured using these Auditec materials.
Effect of Electrode Montage on 500-Hz Tone Burst Evoked Masseter Vestibular Evoked Myogenic Potential
Authors: Thirusangu Vinayagar Pazhani , Sinha Sujeet Kumar
Published: May 2022

Purpose:

Masseter vestibular evoked myogenic potentials (VEMPs) are short-latency myogenic responses obtained in response to electric or acoustic stimulation. It is a relatively newer test that helps assess the vestibulo-trigeminal pathway, thereby gaining more interest in brainstem pathologies like Parkinsonism, multiple sclerosis, and idiopathic random eye movement disorders. The purpose of the study was to compare the effect of zygomatic versus mandibular reference montage on the latency and amplitude of masseter VEMP (mVEMP) using a 500-Hz tone burst stimulus.

Method:

Twenty healthy participants in the age range of 18–29 years, with no complaints of vestibular signs and symptoms, were recruited for the study. VEMP was recorded for all the participants using 500-Hz tone burst stimuli in zygomatic electrode montage and mandibular electrode montage. mVEMP was recorded in both ipsilateral and contralateral modes.

Results:

The Wilcoxon signed-ranks test revealed no significant difference between the zygomatic and mandibular montage for both the latency and amplitude parameters (
p
> .05).

Conclusions:

This study revealed no significant difference in p11 and n21 latencies as well as p11-n21 rectified amplitude between zygomatic and mandibular montage using a 500-Hz tone burst stimulus in young adults. Hence, utilizing a 500-Hz tone burst, mVEMP can be recorded in zygomatic and mandibular electrode montage.
A census of young stellar objects in two line-of-sight star-forming regions toward IRAS 22147+5948 in the outer Galaxy
Authors: Karska Agata , Koprowski Maciej , Solarz Aleksandra , Szczerba Ryszard , Sewiło Marta , Siódmiak Natasza , Elia Davide , Gawroński Marcin , Grzesiak Konrad , Yung Bosco H. K. , Fischer William J. , Kristensen Lars E.
Published: May 2022

Context. Star formation in the outer Galaxy, namely, outside of the Solar circle, has not been extensively studied in part due to the low CO brightness of the molecular clouds linked with the negative metallicity gradient. Recent infrared surveys provide an overview of dust emission in large sections of the Galaxy, but they suffer from cloud confusion and poor spatial resolution at far-infrared wavelengths.

Aims. We aim to develop a methodology to identify and classify young stellar objects (YSOs) in star-forming regions in the outer Galaxy and use it to resolve a long-standing disparity in terms of the distance and evolutionary status of IRAS 22147+5948.

Methods. We used a support vector machine learning algorithm to complement standard color–color and color–magnitude diagrams in our search for YSOs in the IRAS 22147 region, based on publicly available data from the Spitzer Mapping of the Outer Galaxy survey. The agglomerative hierarchical clustering algorithm was used to identify clusters. Then the physical properties of individual YSOs were calculated. The distances were determined using CO 1–0 from the Five College Radio Astronomy Observatory survey.

Results. We identified 13 Class I and 13 Class II YSO candidates using the color-color diagrams, along with an additional 2 and 21 sources, respectively, using the applied machine learning techniques. The spectral energy distributions of 23 sources were modeled with a star and a passive disk, corresponding to Class II objects. The models of three sources include envelopes that are typical for Class I objects. The objects were grouped into two clusters located at a distance of ~2.2 kpc and 5 clusters at ~5.6 kpc. The spatial extent of CO, radio continuum, and dust emission confirms the origin of YSOs in two distinct star-forming regions along a similar line of sight.

Conclusions. The outer Galaxy may serve as a unique laboratory for exploring star formation across environments, on the condition that complementary methods and ancillary data are used to properly account for cloud confusion and distance uncertainties.
Methanol masers in NGC 253 with ALCHEMI
Authors: Humire P. K. , Henkel C. , Hernández-Gómez A. , Martín S. , Mangum J. , Harada N. , Muller S. , Sakamoto K. , Tanaka K. , Yoshimura Y. , Nakanishi K. , Mühle S. , Herrero-Illana R. , Meier D. S. , Caux E. , Aladro R. , Mauersberger R. , Viti S. , Colzi L. , Rivilla V. M. , Gorski M. , Menten K. M. , Huang K.-Y. , Aalto S. , van der Werf P. P. , Emig K. L.
Published: May 2022

Context. Methanol masers of Class I (collisionally pumped) and Class II (radiatively pumped) have been studied in great detail in our Galaxy in a variety of astrophysical environments such as shocks and star-forming regions and are they are helpful to analyze the properties of the dense interstellar medium. However, the study of methanol masers in external galaxies is still in its infancy.

Aims. Our main goal is to search for methanol masers in the central molecular zone (CMZ; inner 500 pc) of the nearby starburst galaxy NGC 253.

Methods. Covering a frequency range between 84 and 373 GHz (λ = 3.6–0.8 mm) at high angular (1.″6 ∼ 27 pc) and spectral (∼8–9 km s−1) resolution with ALCHEMI (ALMA Comprehensive High-resolution Extragalactic Molecular Inventory), we have probed different regions across the CMZ of NGC 253. In order to look for methanol maser candidates, we employed the rotation diagram method and a set of radiative transfer models.

Results. We detect for the first time masers above 84 GHz in NGC 253, covering an ample portion of the J−1 → (J − 1)0 − E line series (at 84, 132, 229, and 278 GHz) and the J0 → (J − 1)1 − A series (at 95, 146, and 198 GHz). This confirms the presence of the Class I maser line at 84 GHz, which was already reported, but now being detected in more than one location. For the J−1 → (J− 1)0 − E line series, we observe a lack of Class I maser candidates in the central star-forming disk.

Conclusions. The physical conditions for maser excitation in the J−1 → (J − 1)0 − E line series can be weak shocks and cloud-cloud collisions as suggested by shock tracers (SiO and HNCO) in bi-symmetric shock regions located in the outskirts of the CMZ. On the other hand, the presence of photodissociation regions due to a high star-formation rate would be needed to explain the lack of Class I masers in the very central regions.
Modelling O-star astrospheres with different relative speeds between the ISM and the star: 2D and 3D MHD model comparison
Authors: Baalmann L. R. , Scherer K. , Kleimann J. , Fichtner H. , Bomans D. J. , Weis K.
Published: May 2022

Context. State of the art simulations of astrospheres are modelled using three-dimensional (3D) magnetohydrodynamics (MHD). An astrospheric interaction of a stellar wind (SW) with its surrounding interstellar medium (ISM) can only generate a bow shock if the speed of the interstellar inflow is higher than the fast magnetosonic speed.

Aims. The differences of astrospheres at differing speeds of the ISM inflow are investigated, and the necessity of the third dimension in modelling is evaluated.

Methods. The model astrosphere of the runaway O-star λ Cephei is computed in both two- and three-dimensional MHD at four different ISM inflow speeds, one of which is barely faster (superfast) and one of which is slower (subfast) than the fast magnetosonic speed.

Results. The two-dimensional (2D) and 3D models of astrospheres with ISM inflow speeds considerably higher than the fast magnetosonic speed are in good agreement. However, in 2D models, where no realistic SW magnetic field can be modelled, the downwind structures of the astrospheres vacillate. Models where hydrodynamic effects are not clearly dominant over the magnetic field show asymmetries, thus necessitating a 3D approach. The physical times of simulations of astrospheres with slow ISM inflows can swiftly exceed the lifetime of the corresponding star. A hitherto unobserved structure has been found downwind of the astrotail in the subfast 3D model.
Reproducibility of 20-min Time-trial Performance on a Virtual Cycling
Platform
Authors: Matta Guilherme , Edwards Andrew , Roelands Bart , Hettinga Florentina , Hurst Philip
Published: May 2022

This study aimed to analyse the reproducibility of mean power output during
20-min cycling time-trials, in a remote home-based setting, using the
virtual-reality cycling software, Zwift. Forty-four cyclists (11 women, 33 men;
37±8 years old, 180±8 cm, 80.1±13.2 kg)
performed 3×20-min time-trials on Zwift, using their own setup.
Intra-class correlation coefficient (ICC), coefficient of variation (CV) and
typical error (TE) were calculated for the overall sample, split into 4
performance groups based on mean relative power output (25% quartiles)
and sex. Mean ICC, TE and CV of mean power output between time-trials were 0.97
[0.95–0.98], 9.4 W [8.0–11.3 W], and 3.7%
[3.2–4.5], respectively. Women and men had similar outcomes (ICC: 0.96
[0.89–0.99] vs. 0.96 [0.92–0.98]; TE: 8.3 W [6.3–13.1]
vs. 9.7 W [8.2–12.2]; CV: 3.8% [2.9–6.1] vs.
3.7% [3.1–4.7], respectively), although cyclists from the first
quartile showed a lower CV in comparison to the overall sample (Q1: 2.6%
[1.9–4.1] vs. overall: 3.7% [3.2–4.5]). Our results
indicate that power output during 20-min cycling time-trials on Zwift are
reproducible and provide sports scientists, coaches and athletes, benchmark
values for future interventions in a virtual-reality environment.
Electronic transport properties of Pb(Bi1−xSbx)2(Te1−ySey)4 topological insulator
Authors: Tokumoto Yuki , Sugimoto Kyoichi , Hattori Yuya , Edagawa Keiichi
Published: May 2022

A series of Pb(Bi1−xSbx)2(Te1−ySey)4 topological insulator crystals with various Sb molar ratios x and Se molar ratios y were fabricated, and their electronic transport properties were studied. Some of the millimeter-sized samples exhibited metallic behavior, while others exhibited semiconducting behavior with a resistivity as high as 48 mΩ cm at 2 K. In addition, Hall coefficients with a large variance were observed for samples from the same ingot, indicating spatial fluctuations in the composition and/or a nonuniform defect distribution. Then, micrometer-sized samples were cut from the millimeter-sized sample with the highest resistivity, and further electrical transport measurements were performed. Some of the micrometer-sized samples exhibited an even higher resistivity than that for the millimeter-sized sample. The magnetoresistance of the semiconducting micrometer-sized samples agreed well with a three-dimensional weak antilocalization/weak localization model in the low-temperature region below 20 K.
An improved framework for the dynamic likelihood filtering approach to data assimilation
Authors: Foster Dallas , Restrepo Juan M.
Published: May 2022

We propose improvements to the Dynamic Likelihood Filter (DLF), a Bayesian data assimilation filtering approach, specifically tailored to wave problems. The DLF approach was developed to address the common challenge in the application of data assimilation to hyperbolic problems in the geosciences and in engineering, where observation systems are sparse in space and time. When these observations have low uncertainties, as compared to model uncertainties, the DLF exploits the inherent nature of information and uncertainties to propagate along characteristics to produce estimates that are phase aware as well as amplitude aware, as would be the case in the traditional data assimilation approach. Along characteristics, the stochastic partial differential equations underlying the linear or nonlinear stochastic dynamics are differential equations. This study focuses on developing the explicit challenges of relating dynamics and uncertainties in the Eulerian and Lagrangian frames via dynamic Gaussian processes. It also implements the approach using the ensemble Kalman filter (EnKF) and compares the DLF approach to the conventional one with respect to wave amplitude and phase estimates in linear and nonlinear wave problems. Numerical comparisons show that the DLF/EnKF outperforms the EnKF estimates, when applied to linear and nonlinear wave problems. This advantage is particularly noticeable when sparse, low uncertainty observations are used.
Compensation of p-type doping in Al-doped 4H-SiC
Authors: Huang Yuanchao , Wang Rong , Zhang Yiqiang , Yang Deren , Pi Xiaodong
Published: May 2022

One of the major challenges of 4H-silicon carbide (4H-SiC) is that the preparation of low resistivity p-type 4H-SiC single crystals lags seriously behind that of low resistivity n-type 4H-SiC single crystals, hindering the development of important 4H-SiC power devices such as n-channel insulated gate bipolar transistors. In particular, the resistivity of p-type 4H-SiC single crystals prepared through the physical vapor transport technique can only be lowered to around 100 mΩ cm. One of the key causes is the incomplete ionization of the p-type dopant Al with an ionization energy ∼0.23 eV. Another factor is the compensating effect. It cannot simply assume nitrogen (N) is the sole compensatory center, since the number of the compensating center is larger than the concentration of N doping. In this work, we systematically investigate the compensation of native defects and self-compensation in Al-doped 4H-SiC. It is found that the positively charged carbon vacancies (VC2+) are also the dominant compensating centers in Al-doped 4H-SiC. When the Al concentration is in the range of 1016–1019 cm−3, the concentration of holes is lower by one order of magnitude than the Al concentration because of the compensation of VC2+. As the Al concentration exceeds 1020 cm−3, the concentration of holes is only in the order of magnitude of 1019 cm−3 owing to the dominant compensation of VC2+ and supplementary self-compensation of interstitial Al (Ali3+). We propose that the passivation of VC2+ as well as quenching is effective to enhance the hole concentration of Al-doped 4H-SiC.
A reduced cost four-component relativistic coupled cluster method based on natural spinors
Authors: Chamoli Somesh , Surjuse Kshitijkumar , Jangid Bhavnesh , Nayak Malaya K. , Dutta Achintya Kumar
Published: May 2022

We present the theory, implementation, and benchmark results for a frozen natural spinors based reduced cost four-component relativistic coupled cluster method. The natural spinors are obtained by diagonalizing the one-body reduced density matrix from a relativistic second-order Møller–Plesset calculation based on a four-component Dirac–Coulomb Hamiltonian. The correlation energy in the coupled cluster method converges more rapidly with respect to the size of the virtual space in the frozen natural spinor basis than that observed in the standard canonical spinors obtained from the Dirac–Hartree–Fock calculation. The convergence of properties is not smooth in the frozen natural spinor basis. However, the inclusion of the perturbative correction smoothens the convergence of the properties with respect to the size of the virtual space in the frozen natural spinor basis and greatly reduces the truncation errors in both energy and property calculations. The accuracy of the frozen natural spinor based coupled cluster methods can be controlled by a single threshold and is a black box to use.
Achieving pair creation via linear and nonlinear Breit–Wheeler processes in dense plasmas irradiated by high-intensity laser pulses
Authors: He Y. , Blackburn T. G. , Toncian T. , Arefiev A.
Published: May 2022

It has been recently shown that over 109 electron–positron pairs can be produced from light alone at an experimentally accessible laser intensity of 5×1022W/cm2 by irradiating a target with a pre-formed channel by two counter-propagating laser pulses. Although targets of variable length and channel density have been successfully fabricated and used in recent experiments involving high-intensity lasers, the impact of these parameters on the pair yield by different pair creation processes is yet to be understood. In this paper, we explore, using two-dimensional particle-in-cell simulations, the impact of the channel density and length on pair production by the linear Breit–Wheeler process, nonlinear Breit–Wheeler process, and Bethe–Heitler process at fixed laser intensity. We find that these parameters can be successfully used to increase the linear Breit–Wheeler pair yield. More importantly, the relative contribution of each process can be adjusted by varying the same parameters. We show that this approach allows us to completely eliminate the yield from the nonlinear Breit–Wheeler process while maintaining a significant yield from the linear Breit–Wheeler process. The Bethe–Heitler process plays a secondary role in the considered system, so the majority of the positrons inside the channel are produced from light alone. Our results indicate that a structured target irradiated by two laser beams has the potential to be a versatile platform for future experimental studies of the Breit–Wheeler pair production processes, with the target parameters serving as control knobs.
Emergence of ligand-to-metal charge transfer in homogeneous photocatalysis and photosensitization
Authors: Li Chenfei , Kong Xin Ying , Tan Zheng Hao , Yang Crystal Ting , Soo Han Sen
Published: May 2022

Light energy can be harnessed by photosensitizers or photocatalysts so that some chemical reactions can be carried out under milder conditions compared to the traditional heat-driven processes. To facilitate the photo-driven reactions, a large variety of chromophores that are operated via charge transfer excitations have been reported because of their typically longer excited-state lifetimes, which are the key to the downstream photochemical processes. Although both metal-to-ligand charge transfers and ligand-to-metal charge transfers are well-established light absorption pathways; the former has been widely adopted in photocatalysis, whereas the latter has recently taken on greater importance in photosensitization applications. In this article, we review the latest developments on ligand-to-metal charge transfer photosensitization by molecular complexes across the periodic table by focusing homogeneous photocatalysis and the use of photophysical measurements and computational calculations to understand the electronic structures, photochemical processes, structure–activity relationships, and reaction mechanisms. We also present our perspectives on the possible future developments in the field.
Thermographic detection of internal defects using 2D photothermal super resolution reconstruction with sequential laser heating
Authors: Lecompagnon J. , Ahmadi S. , Hirsch P. , Rupprecht C. , Ziegler M.
Published: May 2022

Thermographic photothermal super resolution reconstruction enables the resolution of internal defects/inhomogeneities below the classical limit, which is governed by the diffusion properties of thermal wave propagation. Based on a combination of the application of special sampling strategies and a subsequent numerical optimization step in post-processing, thermographic super resolution has already proven to be superior to standard thermographic methods in the detection of one-dimensional defect/inhomogeneity structures. In our work, we report an extension of the capabilities of the method for efficient detection and resolution of defect cross sections with fully two-dimensional structured laser-based heating. The reconstruction is carried out using one of two different algorithms that are proposed within this work. Both algorithms utilize the combination of several coherent measurements using convex optimization and exploit the sparse nature of defects/inhomogeneities as is typical for most nondestructive testing scenarios. Finally, the performance of each algorithm is rated on reconstruction quality and algorithmic complexity. The presented experimental approach is based on repeated spatially structured heating by a high power laser. As a result, a two-dimensional sparse defect/inhomogeneity map can be obtained. In addition, the obtained results are compared with those of conventional thermographic inspection methods that make use of homogeneous illumination. Due to the sparse nature of the reconstructed defect/inhomogeneity map, this comparison is performed qualitatively.
Ultra-high vacuum cleaver for the preparation of ionic crystal surfaces
Authors: Sander Tim , Liu Yi , Pham Tuan Anh , Ammon Maximilian , Devarajulu Mirunalini , Maier Sabine
Published: May 2022

Cleaving single crystals in situ under ultra-high vacuum conditions provides a reliable and straightforward approach to prepare clean and atomically well-defined surfaces. Here, we present a versatile sample cleaver to efficiently prepare ionic crystal surfaces under ultra-high vacuum conditions, which is suitable for preparation of softer materials, such as alkali halides, and harder materials, such as metal oxides. One of the advantages of the presented cleaver design is that the cleaving blade and anvil to support the crystal are incorporated into the device. Therefore, no particularly strong mechanical manipulator is needed, and it is compatible with existing vacuum chambers equipped with an xyz-manipulator. We demonstrate atomically flat terraces and the atomic structure of NaCl(001), KBr(001), NiO(001), and MgO(001) cleavage planes prepared in situ under ultra-high vacuum conditions and imaged by low-temperature non-contact atomic force microscopy.
Plasmon-enhanced third-order optical nonlinearity of monolayer MoS2
Authors: Sun Xiaoli , Chu Lingrui , Ren Feng , Jia Yuechen , Chen Feng
Published: May 2022

Transition metal dichalcogenides (TMDs) have attracted broad interest in photonics owing to their unique electric band structures, which triggers various applications for functional devices. However, the optical absorbance of TMDs is relatively low because of the atomic-scale thickness, limiting further development of TMDs-based nonlinear optical devices. Here, we propose an effective method to enhance the nonlinear optical properties of TMDs using plasmons, which are from embedded silver (Ag) nanoparticles (NPs) inside the fused silica substrate. In such a configuration, the third-order nonlinear absorption coefficient of MoS2 with non-contact Ag NPs is one order of magnitude higher than that of pure monolayer MoS2 under excitation of 515 nm light, and at 1030 nm, the reverse saturable absorption switches to the saturable absorption due to the plasmonic implication. In addition, the mechanism of plasmon-enhanced nonlinear optical properties is confirmed by results of both transient absorption spectroscopy and near-field electromagnetic field simulation. This study on plasmon-enhanced third-order nonlinearity of MoS2 expands the boundaries of TMDs-based optical nonlinearity engineering.
Growth, metal partitioning and antioxidant enzyme activities of mung beans as influenced by zinc oxide nanoparticles under cadmium stress
Authors: Rashid Md Harunur , Rahman Mohammad Mahmudur , Halim Md Abdul , Naidu Ravi
Published: May 2022

Context Cadmium (Cd) toxicity and zinc (Zn) deficiency are of major concerns for crop growth and quality. Moreover, their interactive effects exert some controversial reports. Aims The effects of zinc oxide nanoparticles (ZnO NPs) and Cd on growth, physiology, and metal distribution in mung beans (Vigna radiata L.) was investigated. Methods Seven-day-old seedlings were treated with Zn (0, 1, 2, 4, 8, 16 and 32 μM) and Cd (0, 0.5, 1 μM) for 14 days. Key results Photosynthetic pigments, antioxidant enzyme activities, dry matter yield and metal concentration in tissues were significantly influenced by ZnO NPs and Cd. Considered on its own as a main effect, Zn application (16 μM) enhanced its accumulation in roots, stem and leaf by about 33-fold (314 mg kg−1), 10-fold (60.6 mg kg−1) and 17-fold (110.8 mg kg−1), respectively, compared to control. However, accumulation was slower for interactions with Cd. While leaf Zn increased approximately 27 times (180 mg kg−1) at 32 μM Zn, its interactions with lower and higher Cd increased only 6-fold (41.2 mg kg−1) and 3-fold (21.4 mg kg−1), respectively. Added ZnO NPs up to 4 μM under Cd contamination elevated the leaf Cd, which was restricted by higher supply. However, Cd accumulation in stem and root consistently rose, indicating a synergistic effect. ZnO NPs induced an upregulation of antioxidant enzymes to avert oxidative stress and maintain growth performance. Implications These findings may be suitable for formulating nanomaterials of desired particle sizes and testing on other crop to remediate Cd.
Associations between impulsive personality traits and HIV-related knowledge, beliefs and behaviours among college students in Chengdu, China: a cross-sectional study
Authors: Yu Bin , Huang Yuling , Pei Rong , Han Jiayu , Yang Shujuan
Published: May 2022

Background Impulsive personality traits (IPTs) are key predictors of individuals’ engagement in sexual risk behaviours. This study investigated the associations between IPTs and HIV-related knowledge, beliefs and behaviours among Chinese college students. Methods A sample of 1062 freshmen (first year) and sophomore (second year) students was obtained through stratified random sampling from 11 universities and colleges in Chengdu, China. The sociodemographic information, and HIV-related knowledge, beliefs and behaviours were investigated. A 20-item Short UPPS-P Impulsive Behaviour Scale (S-UPPS-P) was employed to estimate IPTs. Contingency table analyses (χ2) and adjusted logistic regression were used to analyse the association between IPTs and HIV-related knowledge, beliefs and behaviours. Results The S-UPPS-P scale measure of IPTs yielded scores among college students ranging from 26 to 70. Students with a greater level of IPTs were more likely to have a high level of HIV stigma (aOR = 1.46, 95% CI: 1.13–1.89), and a low level of HIV knowledge (aOR = 1.41, 95% CI: 1.11–1.80) and HIV prevention beliefs (aOR = 1.40, 95% CI: 1.09–1.80). All variables of HIV-related behaviours were not significantly associated with IPTs (all P > 0.05). Conclusions Future campus health education should provide HIV education without neglect of early identification of students’ IPTs.