bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Dipole Impact on the Hybrid Nanofluid Flow over an Extending Surface
Authors: Gul Taza , Khan Abbas , Bilal Muhammad , Alreshidi Nasser Aedh , Mukhtar Safyan , Shah Zahir , Kumam Poom
Published: May 2020

The main features of present numerical model is to explore and compare the behavior of simple and hybrid nanoparticles, which were allowed to move on a spreading sheet. The effect of magnetic dipole on hybrid nanofluid flow is considered. A magnetic dipole combined with hybrid nanofluid plays a vital role in controlling the momentum and thermal boundary layers. In view of the impacts of a magnetic dipole on the simple and hybrid nanofluids, steady, laminar and boundary layer flow of $$Cu/{H}_{2}O$$Cu/H2O and $$Cu-A{l}_{2}{O}_{3}/{H}_{2}O$$Cu−Al2O3/H2O are characterized in this analysis. The governing equations of flow problem are diminished to ordinary differential equation (ODE’s) by using similarity approach. For the numerical solution of the nonlinear ODE’s, Runge Kutta order 4th technique has been executed. The impact of various physical constraints, such as volume friction, viscous dissipation, Prandtl number and so on have been sketched and briefly discussed for velocity and temperature profile. In this work, some vital characteristics such as skin friction, Curie temperature and local Nusselt number are chosen for physical and numerical analysis. It has been noted that the hybrid nanofluid is more efficient in thermal conduction due to its strong thermal characteristics as compared to simple nanofluid. From results, it is also observed that the turbulence of fluid flow can be controlled through magnetic dipole.
Significant Day-time Ionospheric Perturbation by Thunderstorms along the West African and Congo Sector of Equatorial Region
Authors: Ogunsua B. O. , Srivastava A. , Bian J. , Qie X. , Wang D. , Jiang R. , Yang J.
Published: May 2020

The equatorial Congo has been recognized as the most active lightning chimney region in the Globe. Although the perturbation of tropospheric thunderstorms on the lower ionosphere has been noticed in the middle latitudes through their transient lightning electric fields or convective gravity waves, the effects on equatorial ionosphere and the horizontal extent of this perturbation remains a mystery because of the difficulties in extracting the effects due to the sporadic nature of the equatorial ionosphere. Here we present observational results showing solid evidence of deviations in ionospheric total electron content (TEC) and its direction of propagation associated with thunderstorms using the method of polynomial filtering, by utilizing the TEC measured from equatorial Global Positioning System (GPS) Receiver stations along the West African region-Congo Basin. The TEC deviations due to the thunderstorms were found to be mostly propagated in a specific direction from the point of the event, with the highest absolute peak TEC at ~±1.5 TECUs. The internal dynamics of the equatorial ionosphere have been found to be suppressed by large thunderstorm effects during the daytime, with negligible impact at night.
The use of spectrograms improves the classification of wheezes and crackles in an educational setting
Authors: Aviles-Solis J. C. , Storvoll I. , Vanbelle Sophie , Melbye H.
Published: May 2020

Chest auscultation is a widely used method in the diagnosis of lung diseases. However, the interpretation of lung sounds is a subjective task and disagreements arise. New technological developments like the use of visSual representation of sounds through spectrograms could improve the agreement when classifying lung sounds, but this is not yet known. In this study, we tested if the use of spectrograms improves the agreement when classifying wheezes and crackles. To do this, we asked twenty-three medical students at UiT the Arctic University of Norway to classify 30 lung sounds recordings for the presence of wheezes and crackles. The sample contained 15 normal recordings and 15 with wheezes or crackles. The students classified the recordings in a random order twice. First sound only, then sound with spectrograms. We calculated kappa values for the agreement between each student and the expert classification with and without display of spectrograms and tested for significant improvement between these two coefficients. We also calculated Fleiss kappa for the 23 observers with and without the spectrogram. In an individual analysis comparing each student to an expert annotated reference standard we found that 13 out of 23 students had a positive change in kappa when classifying wheezes with the help of spectrograms. When classifying crackles 16 out of 23 showed improvement when spectrograms were used. In a group analysis we observed that Fleiss kappa values were k = 0.51 and k = 0.56 (p = 0.63) for classifying wheezes without and with spectrograms. For crackles, these values were k = 0.22 and k = 0.40 (p = <0.01) in the same order. Thus, we conclude that the use of spectrograms had a positive impact on the inter-rater agreement and the agreement with experts. We observed a higher improvement in the classification of crackles compared to wheezes.
Levels of heavy metals in wastewater and soil samples from open drainage channels in Nairobi, Kenya: community health implication
Authors: Kinuthia Geoffrey K. , Ngure Veronica , Beti Dunstone , Lugalia Reuben , Wangila Agnes , Kamau Luna
Published: May 2020

Levels of Mercury (Hg), Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni) & Thallium (Tl) were established in wastewater & soil samples obtained from 8 sites in open drainage channels at Nairobi industrial area, Kenya. Ultra-trace inductively coupled plasma mass spectroscopy (ICP-MS) was used for metal analysis. Temperature, pH & turbidity of wastewater ranged from 16.75 to 26.05 °C; 7.28 to 8.78; 160.33 to 544.69 ppm respectively and within World Health Organization (WHO) allowable limits. Wastewater conductivities in 4 sites ranged from 770 to 1074 µS/cm and above WHO limits at 25 °C. The mean concentrations of the metals in wastewater ranged from 0.0001 to 0.015 ppm in an ascending order of Tl <Cd <Hg <Ni <Cr <Pb. Levels of Cd, Cr & Ni in wastewater were within WHO, World Bank (WB), United States Environmental Protection Agency (US EPA), China, Kenya and India’s Central Pollution Control Board (CPCB) limits while Hg & Tl were above US EPA limits. The mean Pb levels in wastewater (5 sites) were above WHO, US EPA and Kenya allowable limits. Mean levels of the metals in soil samples ranged from 0.085 to 199.99 ppm, with those of Hg, Pb, Cr, Cd & Ni being above WHO limits for agricultural soils. Positive correlations (P < 0.05) for Cd & Hg in soils; and Tl (wastewater) & Cd (soil) were noted. In conclusion, wastewater in open waste channels at Nairobi industrial area had elevated levels of Pb and Hg, while the soil from the same channels had high levels of Hg, Pb, Ni, Cr, and Cd. Good management of Nairobi industrial area effluents is inevitable since it borders densely populated informal settlements which are likely to suffer exposure to toxic wastes. Effective wastewater treatment and reuse is highly recommended.
A novel TEM grid sampler for airborne particles to measure the cell culture surface dose
Authors: Mülhopt Sonja , Schlager Christoph , Berger Markus , Murugadoss Sivakumar , Hoet Peter H. , Krebs Tobias , Paur Hanns-Rudolf , Stapf Dieter
Published: May 2020

The applied surface dose is a key parameter for the measurement of toxic effects of airborne particles by air liquid interface exposure of human lung cells. Besides online measurement of the deposited particle mass by quartz crystal microbalance frequently other dose metrics such as particle size distribution, surface and agglomeration state are required. These particle properties and their spatial distribution can be determined by digital processing of micrographs obtained by transmission electron microscopy (TEM). Here, we report the development and characterization of a novel holder for film coated TEM copper grids, which allows for sampling under identical geometric and ambient conditions as in a cell culture chamber. The sample holder avoids artefacts by reliable grounding of the grids and improves handling of the grids to prevent damage of the sensitive film. This sample holder is applied during exposure experiments with titanium dioxide nanoparticles. The measured dose of 0.2 µg/cm² corresponds well to the mass loading signal of the quartz crystal microbalance. Additionally, the spatial distribution of particles on the sampling surface shows a good homogeneity of deposition. This novel sampling method allows verifying other dosimetry methods and gives additional information about particle properties and homogeneity of the dose.
Vision-based tracking system for augmented reality to localize recurrent laryngeal nerve during robotic thyroid surgery
Authors: Lee Dongheon , Yu Hyeong Won , Kim Seunglee , Yoon Jin , Lee Keunchul , Chai Young Jun , Choi June Young , Kong Hyoun-Joong , Lee Kyu Eun , Cho Hwan Seong , Kim Hee Chan
Published: May 2020

We adopted a vision-based tracking system for augmented reality (AR), and evaluated whether it helped surgeons to localize the recurrent laryngeal nerve (RLN) during robotic thyroid surgery. We constructed an AR image of the trachea, common carotid artery, and RLN using CT images. During surgery, an AR image of the trachea and common carotid artery were overlaid on the physical structures after they were exposed. The vision-based tracking system was activated so that the AR image of the RLN followed the camera movement. After identifying the RLN, the distance between the AR image of the RLN and the actual RLN was measured. Eleven RLNs (9 right, 4 left) were tested. The mean distance between the RLN AR image and the actual RLN was 1.9 ± 1.5 mm (range 0.5 to 3.7). RLN localization using AR and vision-based tracking system was successfully applied during robotic thyroidectomy. There were no cases of RLN palsy. This technique may allow surgeons to identify hidden anatomical structures during robotic surgery.
Physiological and Behavioral Synchrony Predict Group Cohesion and Performance
Authors: Gordon Ilanit , Gilboa Avi , Cohen Shai , Milstein Nir , Haimovich Nir , Pinhasi Shay , Siegman Shahar
Published: May 2020

Interpersonal synchrony contributes to social functioning in dyads, but it remains unknown how synchrony shapes group experiences and performance. To this end, we designed a novel group drumming task in which participants matched their drumming to either predictable or unpredictable tempos. Fifty-one three-person groups were randomly assigned to one of two conditions: synchronized or asynchronized drumming. Outcome measures included electrocardiograms and self-reports of group cohesion and synchrony. The drumming task elicited an increase in physiological synchrony between group members (specifically their hearts’ interbeat intervals). We also found that physiological synchronization and behavioral synchronization predicted individuals’ experience of group cohesion. Physiological synchrony also predicted performance in a subsequent group task that involved freely drumming together. The findings suggest that the behavioral and physiological consequences of synchronization contribute to the formation of group bonds and coordination. They also confirm that insights from translational social neuroscience can inform our knowledge of the development of cohesive and efficacious groups.
A virophage cross-species infection through mutant selection represses giant virus propagation, promoting host cell survival
Authors: Mougari Said , Chelkha Nisrine , Sahmi-Bounsiar Dehia , Di Pinto Fabrizio , Colson Philippe , Abrahao Jonatas , La Scola Bernard
Published: May 2020

Virus adaptation to new hosts is a major cause of infectious disease emergence. This mechanism has been intensively studied in the context of zoonotic virus spillover, due to its impact on global health. However, it remains unclear for virophages, parasites of giant viruses and potential regulators of microbial communities. Here, we present, for the first time to our knowledge, evidence of cross-species infection of a virophage. We demonstrated that challenging the native population of Guarani virophage with two previously unidentified giant viruses, previously nonpermissive to this virophage, allows the selection of a mutant genotype able to infect these giant viruses. We were able to characterize the potential genetic determinant (deletion) carried by the virophage with the expanded-host range. Our study also highlights the relevant biological impact of this host adaptation by demonstrating that coinfection with the mixture containing the mutant virophage abolishes giant virus production and rescues the host cell population from lysis.
Dual roles of the sterol recognition region in Hedgehog protein modification
Authors: Purohit Rahul , Peng Daniel S. , Vielmas Erika , Ondrus Alison E.
Published: May 2020

Nature provides a number of mechanisms to encode dynamic information in biomolecules. In metazoans, there exist rare chemical modifications that occur in entirely unique regimes. One such example occurs in the Hedgehog (Hh) morphogens, proteins singular across all domains of life for the nature of their covalent ligation to cholesterol. The isoform- and context-specific efficiency of this ligation profoundly impacts the activity of Hh morphogens and represents an unexplored facet of Hh ligand-dependent cancers. To elucidate the chemical mechanism of this modification, we have defined roles of the uncharacterized sterol recognition region (SRR) in Hh proteins. We use a combination of sequence conservation, directed mutagenesis, and biochemical assays to specify residues of the SRR participate in cellular and biochemical aspects of Hh cholesterolysis. Our investigations offer a functional portrait of this region, providing opportunities to identify parallel reactivity in nature and a template to design tools in chemical biology.
One-dimensional photonic bound states in the continuum
Authors: Pankin P. S. , Wu B.-R. , Yang J.-H. , Chen K.-P. , Timofeev I. V. , Sadreev A. F.
Published: May 2020

In 1985 Fridriech and Wintgen proposed a mechanism for bound states in the continuum based on full destructive interference of two resonances which can be easily applied to the two- and three-dimensional wave systems. Here we explicitly show that this mechanism can be realized in one-dimensional quantum potential well, owing to destructive interference of electron paths with different spin in tilted magnetic field. Due to one-by-one correspondence between the spin of the electron and the polarization state of light, we have found numerous bound states in the continuum in the one-dimensional photonic system and experimentally confirmed them. The experimental set-up consists of the one-dimensional photonic crystal conjugated with a liquid-crystalline anisotropic defect layer and covered by metal film.
Lactic acid bacteria reduce diabetes symptoms in mice by alleviating gut microbiota dysbiosis and inflammation in different manners
Authors: Wang Gang , Si Qian , Yang Shurong , Jiao Ting , Zhu Huiyue , Tian Peijun , Wang Linlin , Li Xiu , Gong Lei , Zhao Jianxin , Zhang Hao , Chen Wei
Published: May 2020

LAB exhibiting hypoglycaemic effects reduced insulin resistance by contributing to the production of SCFAs and alleviation of inflammation. L. rhamnosus regulated blood lipid more efficiently than Bifidobacterium.
Origin of ferromagnetism and the effect of doping on Fe3GeTe2
Authors: Jang Seung Woo , Yoon Hongkee , Jeong Min Yong , Ryee Siheon , Kim Heung-Sik , Han Myung Joon
Published: May 2020

Fe3GeTe2 is found to have antiferromagnetic ground state spin order in its stoichiometric phase. It is a defect and doping that make this material ferromagnetic.
Facile and efficient preparation of organoimido derivatives of [Mo6O19]2− using accelerated reactions in Leidenfrost droplets
Authors: Cao Jie , Wang QianQian , An ShuQi , Lu ShiFang , Jia QingZhu
Published: May 2020

The first accelerated synthesis of organoimido derivatives of polyoxometalates (POMs) using Leidenfrost droplets with product analysis by ESI-MS.
A covalently linked dual network structure achieved by rapid grafting of poly(p-phenylenediamine)-phosphomolybdic acid on reduced graphene oxide aerogel for improving the performance of supercapacitors
Authors: Gao Jing , Tong Mingxing , Xing Zhengyang , Jin Qiuyang , Zhou Junxi , Chen Lihui , Xu Haolan , Li Guohua
Published: May 2020

Ultra-fast covalent grafting of PPD-PMo12 on rGO (PPD-PMo12@rGO) leads to a covalently linked dual network structure that enhances supercapacitor performance.
N,O-Benzamide difluoroboron complexes as near-infrared probes for the detection of β-amyloid and tau fibrils
Authors: Chen Yimin , Yuan Chang , Xie Tianxin , Li Yuying , Dai Bin , Zhou Kaixiang , Liang Yi , Dai Jiapei , Tan Hongwei , Cui Mengchao
Published: May 2020

In this study, a series of organo difluoroboron probes with a BF2 benzamide moiety was designed, prepared and evaluated as Aβ and Tau probes.
Mechanisms of crystallisation in polysorbates and sorbitan esters
Authors: Nilsson Emelie J. , Lind Tania K. , Scherer Dieter , Skansberger Tatyana , Mortensen Kell , Engblom Johan , Kocherbitov Vitaly
Published: May 2020

Solid-state behaviour of the commonly used pharmaceutical excipient polysorbates, and their non-ethoxylated equivalents.
Impact of the olefin structure on the catalytic cycle and decomposition rates of Hoveyda–Grubbs metathesis catalysts
Authors: Jawiczuk Magdalena , Młodzikowska-Pieńko Katarzyna , Trzaskowski Bartosz
Published: May 2020

Hoveyda–Grubbs catalysts can perform metathesis with mono- and disubstituted olefins bearing chloro and methoxy moieties, but are prone to decomposition with methoxyethene and do not form stable complexes with (Z)-1,2-dichloroethene.
Development of mesopore-containing CON-type zeolite with unique acidic and catalytic properties
Authors: Park Sungsik , Sato Gakuji , Onozuka Hiroaki , Tsutsuminai Susumu , Koike Masakazu , Kuroda Kazuyuki , Gies Hermann , Kondo Junko N. , Yokoi Toshiyuki
Published: May 2020

Post-synthetic hydrothermal treatment in NH4OH solution containing cetyltrimethylammonium bromide.
Efficient solar-driven nitrogen fixation over an elemental phosphorus photocatalyst
Authors: Lin Ling , Zhu Qing , Cheng Aozhi , Ma Liang
Published: May 2020

An elemental semiconductor (red phosphorus) based photocatalyst was developed for nitrogen fixation under full-spectrum irradiation without using any hole scavenger.
Luminescent Ag+ exchanged SOD zeolites with their potential applications in white LEDs
Authors: Yao Decui , Wang Yige , Li Peng , Li Huanrong
Published: May 2020

Luminescent Ag-zeolites with tuned emission and single-phase white-emitting light were achieved by adjusting the lattice parameters of SOD zeolites.
Global geologic carbon storage requirements of climate change mitigation scenarios
Authors: Zahasky Christopher , Krevor Samuel
Published: May 2020

Growth rate analysis indicates IPCC 2100 storage targets are achievable, however tradeoffs exist between CO2 storage resource requirements, storage growth rate, and growth duration, with a ceiling on required storage resources of 2700 Gt.
Ultrasensitive electroanalytical sulfisoxazole sensors amplified with Pd-doped ZnO nanoparticles and modified with 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide
Authors: Bavandpour Razieh , Rajabi Maryam , Karimi-Maleh Hassan
Published: May 2020

In this study, an electrochemical sensor has been introduced by incorporating Pd-doped ZnO nanoparticles (ZnO–Pd/NPs) into a carbon paste (CP) matrix amplified by a conductive binder (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1H3MIBTMSI), in this case) to determine the concentration of the sulfisoxazole (SFX) drug in urine, tablet, and pharmaceutical wastewater samples.
Directionality of P⋯O pnicogen bonding in light of geometry corrected statistical analysis
Authors: Saha Arijit , Veluthaparambath Ragima V. P. , Saha Binoy K.
Published: May 2020

Cone corrected statistical analysis suggests that the X–P⋯O angle prefers linearity which is more prominent in the case of X3P⋯O compared to X4P⋯O pnicogen bonds. This preference also increases with an increase in the electronegativity of X.
Electrospun nanofibers with surface oriented lamellar patterns and their potential applications
Authors: Elishav O. , Shener Y. , Beilin V. , Shter G. E. , Ng B. , Mustain W. E. , Landau Miron V. , Herskowitz Moti , Grader G. S.
Published: May 2020

Surface oriented lamellar structures in ceramic nanofibers for catalysis and energy storage.
Flexible piezoelectric energy harvester with an ultrahigh transduction coefficient by the interconnected skeleton design strategy
Authors: Hao Yijin , Hou Yudong , Fu Jing , Yu Xiaole , Gao Xin , Zheng Mupeng , Zhu Mankang
Published: May 2020

The freeze-casted 2-2 type piezocomposite has an ultrahigh transduction coefficient of 58 213 × 10−15 m2 N−1, which is significantly better than those of previously reported composite materials.
Enantioselective synthesis enabled by visible light photocatalysis
Authors: Hong Bor-Cherng
Published: May 2020

This review summarizes recent developments in visible-light enantioselective photocatalysis reactions, which provide convenient and effective tools for asymmetric synthesis.
Allyl amino-thioxanthone derivatives as highly efficient visible light H-donors and co-polymerizable photoinitiators
Authors: Breloy Louise , Losantos Raúl , Sampedro Diego , Marazzi Marco , Malval Jean-Pierre , Heo Yun , Akimoto Jun , Ito Yoshihiro , Brezová Vlasta , Versace Davy-Louis
Published: May 2020

Allyl-amino thioxanthone derivatives as new visible-light photoinitiators for efficient free-radical, cationic and thiol–ene polymerizations.
Nanocapsules with stimuli-responsive moieties for controlled release employing light and enzymatic triggers
Authors: Seneca Senne , Pramanik Sumit Kumar , D’Olieslaeger Lien , Reekmans Gunter , Vanderzande Dirk , Adriaensens Peter , Ethirajan Anitha
Published: May 2020

The development of stimuli-responsive nanomaterials, that possess tailored functional properties for the release of specific compounds, is of particular interest.
Wide visible-range fluorescence of Eu3+ located in the macroscopic bi-layer ceramic/glass composite
Authors: Shi Haifeng , Yang Jiaxin , Yu Zhimin , Song Yu , Bun Pun Edwin Yue , Zhao Xin , Lin Hai
Published: May 2020

Intense near-white light is observed for CZBL-Eu and GCZBL-Eu, and the heterostructure increases the emission intensity effectively via a complex absorption process.
Effect of guanidinium chloride in eliminating O2− electron extraction barrier on a SnO2 surface to enhance the efficiency of perovskite solar cells
Authors: Yu Miao , Chen Lijia , Li Guannan , Xu Cunyun , Luo Chuanyao , Wang Meng , Wang Gang , Yao Yanqing , Liao Liping , Zhang Sam , Song Qunliang
Published: May 2020

The charge transfer hindrance of adsorbed oxygen species on SnO2 is successfully reduced by modifying it with guanidinium chloride, improving the power conversion efficiency from 15.33% to 18.46% (after modification) with maximum fill factor of 80%.
Aqueous solution photocatalytic synthesis of p-anisaldehyde by using graphite-like carbon nitride photocatalysts obtained via the hard-templating route
Authors: Fernandes Raquel A. , Sampaio Maria J. , Faria Joaquim L. , Silva Cláudia G.
Published: May 2020

Enhanced photocatalytic activity of graphite-like carbon nitride catalysts obtained through hard-templating for a sustainable synthesis of p-anisaldehyde.
Computational understanding of catalyst-controlled borylation of fluoroarenes: directed vs. undirected pathway
Authors: Liu Yu-hua , Jiang Zhong-Jie
Published: May 2020

In this work, density functional theory (DFT) calculations are performed to understand the origin of the regioselective C–H borylation of aromatics catalyzed by Co(i)/iPrPNP and Ir(iii)/dtbpy (4,4-di-tert-butyl bipyridine).
Epoxide and oxetane based liquid crystals for advanced functional materials
Authors: Hoekstra Davey C. , Schenning Albert P. H. J. , Debije Michael G.
Published: May 2020

This work highlights the application of epoxide and oxetane liquid crystals in advanced functional materials including soft robotics, responsive surfaces, and photonic coatings.
Outage analysis of MIMO NLOS‐UV communication systems over atmospheric turbulence channels
Authors: Hariq Sayed Hasan , Karakaya Bahattin , Odabasioglu Niyazi
Published: May 2020

Rich scattering of the signals in the ultraviolet (UV) band of electromagnetic spectrum enables non‐line‐of‐sight (NLOS) outdoor wireless connectivity. It eliminates the line‐of‐sight requirement of the links which are using the signals in the infra‐red band. Besides scattering losses, UV signals also suffer from atmospheric turbulence‐induced fading. The turbulent atmospheric channel causes fluctuations in the received signal intensity of a NLOS ultraviolet (NLOS‐UV) link, resulting in power loss and the performance degradation at the receiver. In this study, spatial diversity techniques are investigated as an appealing fading mitigation technique for NLOS‐UV systems over atmospheric turbulence channels. In particular, the outage probabilities of multiple‐input‐single‐output (MISO), single‐input‐multiple‐output (SIMO), and multiple‐input‐multiple‐output (MIMO) links are studied, and the outage performances are investigated for different system configurations. Closed‐form expressions are derived for the outage probability of MISO, SIMO, and MIMO systems, and the accuracy of the derivations is confirmed through Monte Carlo simulations. The outage probability of single‐input‐single‐output link is also derived as a benchmark. The results demonstrate significant performance improvements through deployment and proper configuration of MIMO systems in NLOS‐UV communication links.
Smart feature extraction and classification of hyperspectral images based on convolutional neural networks
Authors: Hamouda Maissa , Ettabaa Karim Saheb , Bouhlel Med Salim
Published: May 2020

Hyperspectral satellite imagery (HSI) is an advanced technology for object detection because it provides a large amount of information. Thus, the classification of HSIs is very complicated, so the methods of reducing spectral or spatial information generally degrade the quality of classification. In order to solve this problem and guarantee faster and more efficient processing, we propose a smart feature extraction (SFE) and classification by convolutional neural network (2D‐CNN) method made up of two parts. The first consists in reducing spectral information by a probabilistic method based on the Softmax function. The second is classification by processing batches of data in the proposed CNN network. The method was tested on two public hyperspectral images (Indian Pines and SalinasA) to prove its effectiveness in increasing classification accuracy and reducing computing time.
Performance‐traffic‐trade‐off of two novel hard decision and two soft decision fusion periodogram‐based algorithms for cooperative spectrum sensing under unreliable reporting channel
Authors: dos Santos Costa Lucas , de Souza Rausley A.A.
Published: May 2020

Spectrum sensing is one of the most important tasks of cognitive radios (CRs) to detect idle bands for opportunistic access. In centralised cooperative sensing, CRs sense a target band and share sensing information via reporting channel with a fusion centre to decide whether the sensed band is vacant or not. This information can be raw data in soft decision fusion scheme or local decisions on the channel occupation state in hard decision fusion one. A soft decision typically achieves better detection performances, but the hard one intrinsically offers smaller data traffic. This study proposes two periodogram‐based hard decision algorithms and makes a detailed performance‐traffic‐trade‐off with two periodogram‐based soft‐decision algorithms. All the approaches are based on the circular folding cooperative power spectral density split cancellation algorithm. Performance analyses are made under unavoidable errors in the reporting channel. In the first assumption, the simple memoryless binary symmetric channel is adopted. In the second one, the more realist memory Gilbert–Elliott channel is assumed. Results show that the proposed schemes are sensitive to reporting errors, but performance loss can be supplanted with channel encoding, yet keeping the traffic smaller than in the soft decision without channel encoding.
X-shooter survey of disk accretion in Upper Scorpius
Authors: Manara C. F. , Natta A. , Rosotti G. P. , Alcalá J. M. , Nisini B. , Lodato G. , Testi L. , Pascucci I. , Hillenbrand L. , Carpenter J. , Scholz A. , Fedele D. , Frasca A. , Mulders G. , Rigliaco E. , Scardoni C. , Zari E.
Published: May 2020

Determining the mechanisms that drive the evolution of protoplanetary disks is a necessary step toward understanding how planets form. For this work, we measured the mass accretion rate for young stellar objects with disks at age > 5 Myr, a critical test for the current models of disk evolution. We present the analysis of the spectra of 36 targets in the ∼5–10 Myr old Upper Scorpius star-forming region for which disk masses were measured with ALMA. We find that the mass accretion rates in this sample of old but still surviving disks are similarly high as those of the younger (∼1−3 Myr old) star-forming regions of Lupus and Chamaeleon I, when considering the dependence on stellar and disk mass. In particular, several disks show high mass accretion rates ≳10−9 M⊙ yr−1 while having low disk masses. Furthermore, the median values of the measured mass accretion rates in the disk mass ranges where our sample is complete at a level ∼60−80% are compatible in these three regions. At the same time, the spread of mass accretion rates at any given disk mass is still > 0.9 dex, even at age > 5 Myr. These results are in contrast with simple models of viscous evolution, which would predict that the values of the mass accretion rate diminish with time, and a tighter correlation with disk mass at age > 5 Myr. Similarly, simple models of internal photoevaporation cannot reproduce the observed mass accretion rates, while external photoevaporation might explain the low disk masses and high accretion rates. A possible partial solution to the discrepancy with the viscous models is that the gas-to-dust ratio of the disks at ∼5–10 Myr is significantly different and higher than the canonical 100, as suggested by some dust and gas disk evolution models. The results shown here require the presence of several interplaying processes, such as detailed dust evolution, external photoevaporation, and possibly MHD winds, to explain the secular evolution of protoplanetary disks.
An in-depth reanalysis of the alleged type Ia supernova progenitor Henize 2−428
Authors: Reindl N. , Schaffenroth V. , Miller Bertolami M. M. , Geier S. , Finch N. L. , Barstow M. A. , Casewell S. L. , Taubenberger S.
Published: May 2020

Context.The nucleus of the planetary nebula Hen 2-428 is a short orbital-period (4.2 h), double-lined spectroscopic binary, whose status as a potential supernova type Ia progenitor has raised some controversy in the literature.

Aims.With the aim of resolving this debate, we carried out an in-depth reanalysis of the system.

Methods.Our approach combines a refined wavelength calibration, thorough line-identifications, improved radial-velocity measurements, non-LTE spectral modeling, as well as multi-band light-curve fitting. Our results are then discussed in view of state-of-the-art stellar evolutionary models.

Results.Besides systematic zero-point shifts in the wavelength calibration of the OSIRIS spectra which were also used in the previous analysis of the system, we found that the spectra are contaminated with diffuse interstellar bands. Our Voigt-profile radial velocity fitting method, which considers the additional absorption of these diffuse interstellar bands, reveals significantly lower masses (M1 = 0.66 ± 0.11M⊙andM2 = 0.42 ± 0.07M⊙) than previously reported and a mass ratio that is clearly below unity. Our spectral and light curve analyses lead to consistent results, however, we find higher effective temperatures and smaller radii than previously reported. Moreover, we find that the red-excess that was reported before to prove to be a mere artifact of an outdated reddening law that was applied.

Conclusions.Our work shows that blends of He II λ 5412 Å with diffuse interstellar bands have led to an overestimation of the previously reported dynamical masses of Hen 2−428. The merging event of Hen 2−428 will not be recognised as a supernova type Ia, but most likely leads to the formation of a H-deficient star. We suggest that the system was formed via a first stable mass transfer episode, followed by common envelope evolution, and it is now composed of a post-early asymptotic giant branch star and a reheated He-core white dwarf.
The Role of Ultrasound in the Diagnosis of Soft Tissue Tumors
Authors: Aparisi Gómez Maria Pilar , Errani Costantino , Lalam Radhesh , Vasilevska Nikodinovska Violeta , Fanti Stefano , Tagliafico Alberto Stefano , Sconfienza Luca Maria , Bazzocchi Alberto
Published: May 2020

The vast majority of soft tissue masses are benign. Benign lesions such as superficial lipomas and ganglia are by far the most common soft tissue masses and can be readily identified and excluded on ultrasound (US). US is an ideal triaging tool for superficial soft tissue masses. Compared with magnetic resonance imaging (MRI), High-resolution US is inexpensive, readily available, well tolerated, and safe. It also allows the radiologist to interact with the patient as a clinician. In this review, we describe and illustrate the lesions with typical (diagnostic) US features. When the appearances of the lesion are not typical as expected for a benign lesion, lesions are deep or large, or malignancy is suspected clinically, MRI and biopsy are needed. The management of suspicious soft tissue tumors has to be carefully planned by a multidisciplinary team involving specialized surgeons and pathologists at a tumor center.
Undergraduate Students’ Acceptance of a Reciprocating One-File System for Endodontic Treatment
Authors: Mahmoodi Benjamin , Azaripour Adriano , Sagheb Kawe , Sagheb Keyvan , Willershausen Brita , Weusmann Jens
Published: May 2020

Objectives Reciprocating endodontic one-file systems are a comparatively new method for root canal shaping. Even though the mechanical properties are comparable to modern rotating mechanical systems, data about subjective assessment and application quality are scarce. This study evaluates the reciprocating one-file system in undergraduate education.

Materials and Methods A total of 42 undergraduate students without experience regarding reciprocating file systems filled in a questionnaire in four different points in time (t
1–t
4) anonymously. The questionnaire was based on a numerical rating scale ranging from 0 to 10.

Statistical Analysis A least significant difference post-hoc analysis comparing the group average values was performed. The adjusted level of significance was p < 0.004 after Bonferroni correction.

Results All rating scores increased after the first theoretical instruction. After the first practical training in artificial root canals in resin blocks and extracted teeth (t
2), the estimation of “time efficiency” (p = 0.002), “handling” (p < 0.001), and “overall impression” (p < 0.001) improved significantly. The “overall impression” remained constant and showed no significant changes after the first practical training.

Conclusions Reciprocating systems seem to show a good acceptance among first time users. Initial concerns about “work safety” decrease during every step of the educational process. Reciprocating one-file systems are a safe and well-accepted method in undergraduate teaching.
A Novel Application of Digital Microscope for Microsurgery Training
Authors: Sayadi Lohrasb R. , Fligor Jennifer E. , Couchois Sean , Evans Gregory R. D. , Widgerow Alan D. , Lanier Brock
Published: May 2020

Background Time spent under the microscope is often a limiting factor as plastic surgery residents work toward proficiency in microsurgery. This study describes and assesses a novel application of a digital microscope compatible with smart devices which can consistently and reliably magnify microsurgical fields.

Methods A digital microscope was used to display an “operating” field on a tablet device. Two junior plastic surgery residents participated in multiple training sessions. During each session, residents completed two sessions of a knot-tying task and a chicken vessel anastomosis task. The sessions were recorded on the tablet, photographed, and graded by an experienced microsurgeon utilizing three standardized microsurgery training scales (OWOMSA, OSATS, and Global scale) for evaluation. Between sessions, the residents received feedback from the experienced microsurgeon.

Results Statistically significant improvements (p < 0.05) in microsurgical technique were observed across 16 areas assessed by the standardized evaluation scales. Additionally, the residents' surveys suggest favorable attitudes toward the digital microscope and its value as a training device.

Conclusion Traditional operating microscopes present considerable barriers for effective microsurgical training. The digital microscope analyzed in the present study provides solutions to several of these barriers: it is economical, lightweight, portable, and can be set up by the trainee on any flat surface; photographing and recording capabilities via the connected tablet device make the digital microscope setup optimized for education. Our study demonstrates measurable improvements in trainee's skills with use of—as well as favorable trainee attitudes toward—the digital microscope, which could present a valuable addition to plastic surgery education.
Recipient Vessel Thrombectomy and Anastomosis within the Zone of Injury in Microvascular Extremity Reconstruction
Authors: Powers Jeremy M. , Choi Jaime H. , Kale Santosh S.
Published: May 2020

Background In traumatic extremity reconstruction, it is preferable to perform microvascular anastomoses outside the zone of injury. Alternatively, a recipient-vessel thrombectomy can be performed to improve the arterial inflow, potentially avoiding further proximal dissection and the use of a vein graft. The objective of this study was to evaluate the outcomes of microvascular anastomosis after thrombectomy in the zone of injury.

Methods A retrospective review of patients who underwent free tissue transfer for traumatic extremity reconstruction by the senior author from 2013 to 2017 was conducted. Patient demographic and clinical data were gathered as well as use of vein grafts, recipient-vessel thrombectomy, postoperative anticoagulation, and flap outcomes.

Results A total of 23 patients underwent 24 free flap procedures for traumatic extremity reconstruction. Ten patients underwent recipient-vessel thrombectomy with 2-Fr Fogarty catheter and were placed on postoperative anticoagulation. In this group overall, there was one case of flap loss due to late wound infection resulting in a 90% success rate. A total of 13 patients underwent 14 free flaps without the use of thrombectomy and vein grafts were performed for 3/14 (21%) patients. In this group, there were four cases of flap loss, resulting in a 71% overall success rate.

Conclusion In traumatic extremity reconstruction, if the artery appears to be visibly appropriate with weak inflow, one may consider attempting thrombectomy to restore pulsatile flow prior to harvesting a vein graft. This study suggests this may be effective and safe with no anastomosis-related flap loss in the thrombectomy group. Further research is required to confirm our results.
COVID-19 in Pregnant Women: Case Series from One Large New York City Obstetrical Practice
Authors: Fox Nathan S. , Melka Stephanie
Published: May 2020

Objective This study aimed to report a case series of pregnant women in New York City with confirmed or presumed coronavirus disease (COVID-19) infection.

Study Design Beginning March 22, 2020, all pregnant women from one large obstetrical practice in New York City were contacted regularly to inquire about symptoms of COVID-19 (fever, cough, shortness of breath, malaise, anosmia), or sick contacts. A running log was kept of these patients, as well as all patients who underwent COVID-19 testing. For this report, we included every patient with suspected COVID-19 infection, which was defined as at least two symptoms, or a positive COVID-19 nasopharyngeal polymerase chain reaction test.

Results From March 22, 2020 until April 30, 2020, 757 pregnant women in our practice were evaluated and 92 had known or suspected COVID-19 (12.2%, 95% confidence interval [CI]: 10.0–14.7%). Of these 92 women, 33 (36%) had positive COVID-19 test results. Only one woman required hospital admission for 5 days due to COVID-19 (1.1%, 95% CI: 0.2–5.9%). One other woman received home oxygen. No women required mechanical ventilation and there were no maternal deaths. One woman had an unexplained fetal demise at 14 weeks' gestation around the time of her COVID-19 symptoms. Twenty one of the 92 women have delivered, and all were uncomplicated.

Conclusions Among 92 women with confirmed or presumed COVID-19, the overall morbidity was low. These preliminary results are encouraging for pregnant women during the COVID-19 pandemic.

Key Points
A three-dimensional Dionne model for multipactor simulations
Authors: Plaçais A. , Belhaj M. , Hillairet J. , Puech J.
Published: May 2020

The multipactor phenomenon is characterized by a very fast growth of the electronic population in radio-frequency (RF) devices under vacuum. As this effect limits the transmissible RF power and can harm RF systems, it has been widely studied during the last few decades. Due to the high cost of experimental tests, simulation tools are heavily used to predict the threshold of multipactor growth. However, their reliability is limited for complex configurations, e.g., when dielectrics or magnetic fields are present. A crucial element of these multipactor simulations is the secondary-emission model. Dionne's model is able to model both metals and dielectrics secondary emission but is one-dimension only. As the three-dimensional aspect is essential for complex configurations, the Dionne model is extended to three-dimensions. Measurements of the total electron emission yield have been carried out at the ONERA and show a good agreement for low-impact energy and low-impact angle electrons, which is relevant in multipactor simulations.
Enhanced high-frequency microwave absorption in core-shell nanocapsules with atomic-scale oxygen substitutions
Authors: Li Yixing , Zheng Yun , Liu Rongge , Rao Yi , Su Rui , Yu Jieyi , Liu Xianguo , Guan Pengfei , Guo Junjie , Zhang Xuefeng , Qin Gaowu
Published: May 2020

High-performance electromagnetic wave absorption materials constitute key components of microelectronic devices. Traditional absorbents possess magnetic losses and/or dielectric losses, while the experimental approach for their simultaneous enhancement is still lacking. Here, we demonstrate that the core/shell structural Ni@C nanocapsules, functionalized by atomic-scale oxygen substitutions that can be formed catalytically by highly defective graphitic structure, present enhanced dielectric loss capacities at gigahertz. In particular, >90% of the microwave energy could be attenuated for a planar absorber with a thickness down to 1–1.5 mm at 7.6–13.8 GHz. Experimental characterizations coupled with density functional theory calculations further evidence that the capacity enhancement is ascribed to the structure breaking at the heterogeneous substitutional zones, resulting in the intrinsic polarization of carbon–oxygen heterostructures. The present study shows a new mentality of designing for optimizing electromagnetic wave absorption materials and also has pointed out the atomic-scale structural origin of the electromagnetic response performance.
Systematic investigation of synthetic polyelectrolyte bottlebrush solutions by neutron and dynamic light scattering, osmometry, and molecular dynamics simulation
Authors: Horkay Ferenc , Chremos Alexandros , Douglas Jack F. , L. Jones Ronald , Lou Junzhe , Xia Yan
Published: May 2020

There is a great interest in the synthesis and characterization of polyelectrolytes that mimic naturally occurring bottlebrush polyelectrolytes to capitalize on the unique properties of this class of macromolecules. Charged bottlebrush polymers form the protective mucus layer in the lungs, stomach, and orifices of animals and provide osmotic stabilization and lubrication to joints. In the present work, we systematically investigate bottlebrush poly(sodium acrylates) through a combination of measurements of solution properties (osmometry, small-angle neutron scattering, and dynamic light scattering) and molecular dynamics simulations, where the bottlebrush properties are compared in each case to their linear polymer counterparts. These complementary experimental and computational methods probe vastly different length- and timescales, allowing for a comprehensive characterization of the supermolecular structure and dynamics of synthetic polyelectrolyte bottlebrush molecules in solution.
Faraday-cage-assisted etching of suspended gallium nitride nanostructures
Authors: Gough Geraint P. , Sobiesierski Angela D. , Shabbir Saleem , Thomas Stuart , Beggs Daryl M. , Taylor Robert A. , Bennett Anthony J.
Published: May 2020

We have developed an inductively coupled plasma etching technique using a Faraday cage to create suspended gallium-nitride devices in a single step. The angle of the Faraday cage, gas mix, and chamber condition define the angle of the etch and the cross-sectional profile, which can feature undercut angles of up to 45°. We fabricate singly- and doubly-clamped cantilevers of a triangular cross section and show that they can support single optical modes in the telecom C-band.
Transport coefficients of model lubricants up to 400 MPa from molecular dynamics
Authors: Kondratyuk N. , Lenev D. , Pisarev V.
Published: May 2020

In this paper, the predictive power of molecular dynamics methods is demonstrated for the cases of model paraffinic and aromatic lubricant liquids at pressures up to 400 MPa. The shear viscosity and self-diffusion coefficients are calculated for 2,2,4-trimethylpentane (C8H18) at 298 K and 1,1-diphenylethane (C14H14) at 333 K. Three force fields with different levels of accuracy are compared by the ability to predict the experimental data. The Stokes–Einstein correlation between viscosity and self-diffusion is demonstrated for both compounds.
Coarse-graining, compressibility, and thermal fluctuation scaling in dissipative particle dynamics employed with pre-determined input parameters
Authors: Mai-Duy N. , Phan-Thien N. , Nguyen T. Y. N. , Tran-Cong T.
Published: May 2020

In this study, a Dissipative Particle Dynamics (DPD) method is employed with its input parameters directly determined from the fluid properties, such as the fluid mass density, water compressibility, and viscosity. The investigation of thermal fluctuation scaling requires constant fluid properties, and this proposed DPD version meets this requirement. Its numerical verifications in simple or complex fluids under viscometric or non-viscometric flows indicate that (i) the level of thermal fluctuations in the DPD model for both types of fluids is consistently reduced with an increase in the coarse-graining level and (ii) viscometric or non-viscometric flows of a model fluid at different coarse-graining levels have a similar behavior. Furthermore, to reduce the compressibility effect of the DPD fluid in simulating incompressible flows, a new simple treatment is presented and shown to be very effective.