bluuebunny/crossref_metadata_2025 huggingface dataset:
ISO-ChaI 52: a weakly accreting young stellar object with a dipper light curve
Authors: Frasca A. , Manara C. F. , Alcalá J. M. , Biazzo K. , Venuti L. , Covino E. , Rosotti G. , Stelzer B. , Fedele D.
Published: July 2020

We report the discovery of periodic dips in the multiband light curve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one of the peculiar objects that display very low or negligible accretion in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optically thick circumstellar disks. We have analyzed a spectrum obtained at the Very Large Telescope with the X-shooter spectrograph with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the Rapid Eye Mount telescope and from the literature, have allowed us to model the spectral energy distribution and to estimate the size and temperature of the inner and outer disk. Based on the rotational period of the star-disk system of 3.45 days, we estimate a disk inclination of 36°. The depth of the dips in different bands has been used to gain information about the occulting material. A single extinction law is not able to fit the observed behavior, while a two-component model of a disk warp composed of a dense region with a gray extinction and an upper layer with an extinction as in the interstellar medium provides a better fit to the data.
The GAPS Programme at TNG
Authors: Baratella M. , D’Orazi V. , Biazzo K. , Desidera S. , Gratton R. , Benatti S. , Bignamini A. , Carleo I. , Cecconi M. , Claudi R. , Cosentino R. , Ghedina A. , Harutyunyan A. , Lanza A. F. , Malavolta L. , Maldonado J. , Mallonn M. , Messina S. , Micela G. , Molinari E. , Poretti E. , Scandariato G. , Sozzetti A.
Published: July 2020

Context. The detailed chemical composition of stars is important in many astrophysical fields, among which is the characterisation of exoplanetary systems. Previous studies seem to indicate an anomalous chemical pattern of the youngest stellar population in the solar vicinity that has sub-solar metal content. This can influence various observational relations linking the properties of exoplanets to the characteristics of the host stars, for example the giant planet-metallicity relation.

Aims. In this framework, we aim to expand our knowledge of the chemical composition of intermediate-age stars and understand whether these peculiarities are real or related to spectroscopic analysis techniques.

Methods. We analysed high-resolution optical and near-infrared spectra of intermediate-age stars (<700 Myr) that have been observed simultaneously with HARPS-N and GIANO-B spectrographs in GIARPS mode. To overcome issues related to the young ages of the stars, we applied a new spectroscopic method that uses titanium lines to derive the atmospheric parameters, in particular surface gravities and microturbulence velocity parameter. We derived abundances of C I, Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Cr I, Cr II, Fe I, Fe II, Ni I, and Zn I.

Results. The lack of systematic trends between elemental abundances and effective temperatures validates our methods. However, we observed that the coolest stars in the sample, where Teff < 5400 K, display higher abundances for the ionised species, in particular Cr II, and for high-excitation potential C I lines.

Conclusions. We found a positive correlation between the higher abundances measured of C I and Cr II and the activity index log RHK′. Instead, we found no correlations between the C abundances obtained from CH molecular band at 4300 Å and both effective temperatures and activity. Thus, we suggest that these are better estimates for C abundances in young and cool stars. Finally, we found an indication of an increasing abundance ratio [X/H] with the condensation temperature for HD 167389, indicating possible episodes of planet engulfment.
À quand la lumière au bout du tunnel ?
Authors: Behar-Cohen Francine
Published: July 2020

Les maladies de la rétine sont des causes fréquentes de handicap visuel dans les pays industrialisés. En 2040, 25 millions d’européens seront atteints de dégénérescence maculaire liée à l’âge (DMLA) et 8,6 millions de rétinopathie diabétique. La myopie forte est une cause croissante de cécité, en Asie et dans le reste du monde. En 2050, on estime que 50 % de la population mondiale sera myope. La modification de notre environnement lumineux ne serait pas étrangère à cet allongement du globe oculaire en cause dans la myopie. Si les maladies rétiniennes les plus fréquentes sont multifactorielles, impliquant des prédispositions génétiques complexes, le vieillissement, des facteurs métaboliques et environnementaux, un petit nombre de patients sont atteints de maladies rétiniennes monogéniques qui servent de modèles pour l’étude de maladies complexes multifactorielles.
Le cerveau adulte produit de nouveaux neurones pour restaurer l’équilibre après une perte vestibulaire
Authors: Tighilet Brahim , Rastoldo Guillaume , Chabbert Christian
Published: July 2020

Un phénomène appelé « compensation vestibulaire » se produit après une atteinte vestibulaire périphérique. Ce processus, qui permet un retour progressif de l’équilibre, se produit principalement au sein des noyaux vestibulaires du tronc cérébral, et met en jeu une mosaïque de réarrangements structurels. Parmi ceux-ci, la neurogenèse vestibulaire réactionnelle (NGVR) adulte est peut-être la plus inattendue, car elle se produit dans une région du cerveau qui n’a jamais été signalée auparavant comme neurogène. La survie et la fonctionnalité de ce réseau neuronal nouvellement généré dépendent de son intégration dans les réseaux préexistants des noyaux désafférentés. Cette organisation permet au cerveau d’utiliser les apports d’autres modalités sensorielles pour faciliter le rétablissement de la posture et de l’équilibre. C’est à ce jour le meilleur exemple du rôle réparateur de la neurogenèse adulte. Ces observations soulèvent de nombreuses questions sur la pertinence physiologique de la NGVR.
Mobilität und Sturzprävention bei selbstständig lebenden älteren Menschen
Authors: Freiberger Ellen , Sieber Cornel C. , Singler Katrin
Published: July 2020

An increasing proportion of oldest old persons (over 80 years) accompanies the demographic change. Furthermore, the gender ration will also change and the percentage of older men will increase. Mobility is an important factor for maintaining independence and for “healthy aging”. Mobility has to be regarded in the context of individual and environmental factors. With increasing age, the risk of mobility limitation increases. Next to mobility, falls are also a drastic experience for older persons and cannot only have physical consequences like injuries but also psychological consequences as fall-related psychological concerns. These psychological consequences can produce negative behavior e. g. reducing physical activity.
Polymyalgia rheumatica mit und ohne Großgefäßvaskulitis
Authors: Schmidt Wolfgang A.
Published: July 2020

Polymyalgia rheumatica (PMR) is characterized by rapidly evolving shoulder and pelvic girdle pain with fatigue, weight loss, night sweats and elevated CRP and ESR. Giant cell arteritis (GCA) can occur in PMR and vice versa. Headache and scalp tenderness are typical for GCA. GCA may be complicated by visual loss or by strokes.

Imaging, particularly ultrasound, is helpful for distinguishing PMR from similar conditions such as shoulder osteoarthritis, rheumatoid arthritis and chondrocalcinosis. Subdeltoid bursitis, biceps tenosynovitis and hip joint effusions are common in PMR. The diagnosis of GCA needs to be either confirmed by imaging or by histology. Ultrasound is the imaging method of choice provided that expertise and adequate equipment are available. Inflamed arteries exhibit a concentric wall thickening. Patients with extracranial GCA are younger, more often female. Vasculitis commonly involves the aorta, subclavian arteries, axillary arteries and other arteries. The diagnosis of extracranial GCA may be confirmed by ultrasound, CT, MRI or PET.

Prednisolone with a starting dose of 15–25 mg/d for PMR and of 40–60 mg/d for GCA results in rapid improvement of symptoms. Fast-track clinics provide clinical and ultrasound examinations by experts within 24 hours. Their introduction led to a decrease of visual loss in GCA. The prednisolone dose can be discontinued within 1 year in about 50 % of GCA patients. Additional treatment with tocilizumab allows to reduce flares and decrease glucocorticoid doses. Tocilizumab is particularly useful in patients with relapses and with increased risk of glucocorticoid side effects.
Position Paper of the German Society for Interventional Radiology (DeGIR) on Prostatic Artery Embolization
Authors: Kovács Attila , Bücker Arno , Grimm Marc-Oliver , Habermann Christian R. , Katoh Marcus , Massmann Alexander , Mahnken Andreas H. , Meyer Bernhard C. , Moche Michael , Reimer Peter , Teichgräber Ulf , Wacker Frank K. ,   In Zusammenarbeit mit der DeGIR-Lenkungsgruppe Wissenschaft und dem DeGIR-Vorstand
Published: July 2020

Background In recent years prostate artery embolization (PAE) evolved into a clinically established minimally invasive endovascular treatment option for lower urinary tract symptoms caused by benign prostate syndrome (BPS).

Methods In this interdisciplinary position paper, initiated by the steering group for research of the German Society for Interventional Radiology (IR), the method of PAE is presented and discussed in the context of current evidence.

Results PAE is a safe IR procedure for the treatment of BPS. In terms of symptom relief, measured with the IPSS (International Prostate Symptom Score), the PAE has comparable effect, similar to the historic gold standard, transurethral resection (TUR) of the prostate. With regard to reducing subvesical obstruction PAE is inferior to TUR, but does not limit subsequent surgery. Based on current evidence, PAE is recommended by the British National Institute for Health and Care Excellence as an alternative therapy. The feasibility under local anaesthesia and the preservation of sexual function are important arguments for patients in favour of interventional therapy. Patient selection and therapy concepts require close interdisciplinary collaboration between urologists and radiologists.

Conclusion Effectiveness and safety of PAE for the treatment of BPS are proven. Further randomized trials should focus on long term outcome and help to identify most suitable indications for PAE.

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Citation Format
Copper-Catalyzed Methylthiolation of Aryl Iodides and Bromides with Dimethyl Disulfide in Water
Authors: Wu Xiang-mei , Wang Ying-yu , Yang Ming-hua
Published: July 2020

An efficient route to aryl methyl sulfides through the copper-catalyzed coupling reaction of aryl iodides or bromides with dimethyl disulfide in water is described. Electron-donating and electron-withdrawing functional groups in the substrates were tolerated, and the corresponding products were obtained in moderate to good yields.
Isoprene: A Promising Coupling Partner in C–H Functionalizations
Authors: Chen Qing-An , Zhang Wei-Song , Hu Yan-Cheng
Published: July 2020

Five-carbon dimethylallyl units, such as prenyl and reverse-prenyl, are widely distributed in natural indole alkaloids and terpenoids. In conventional methodologies, these valuable motifs are often derived from substrates bearing leaving groups, but these processes are accompanied by the generation of stoichiometric amounts of by-products. From an economical and environmental point of view, the basic industrial feedstock isoprene is an ideal alternative precursor. However, given that electronically unbiased isoprene might undergo six possible addition modes in the coupling reactions, it is difficult to control the selectivity. This article summarizes the strategies we have developed to achieve regioselective C–H functionalizations of isoprene under transition-metal and acid catalysis.

1 Introduction

2 Catalytic Coupling of Indoles with Isoprene

3 Catalytic Coupling of Formaldehyde, Arenes and Isoprene

4 Catalytic Coupling of 4-Hydroxycoumarins with Isoprene

5 Catalytic Coupling of Cyclic 1,3-Diketones with Isoprene

6 Conclusion and Outlook
Lifetime Psychosocial Stress Exposure Associated with Hypertensive Disorders of Pregnancy
Authors: Caplan Madeleine , Keenan-Devlin Lauren S. , Freedman Alexa , Grobman William , Wadhwa Pathik D. , Buss Claudia , Miller Gregory E. , Borders Ann E.B.
Published: July 2020

Objective Hypertensive disorders of pregnancy (HDP) complicate 5 to 10% of all pregnancies and are a major cause of pregnancy-related morbidity. Exposure to psychosocial stress has been associated with systemic inflammation and adverse birth outcomes in pregnant women. Thus, it is probable that psychosocial stress and inflammation play a role in the development of HDP. The primary objective of this analysis was to determine if a woman's lifetime psychosocial stress exposure was associated with an increased risk of HDP. Additionally, we examined whether serum inflammation was an underlying biological mediator for this relationship.

Study Design A multisite prospective study was conducted in a sociodemographically diverse cohort of 647 pregnant women. At a study visit between 12 and 206/7 weeks' gestation, maternal psychosocial stress was assessed with six validated assessments and inflammation was measured via log-transformed serum concentrations of interferon-γ, interleukin (IL)-10, IL-13, IL-6, IL-8, and tumor necrosis factor-α. A composite stress score was calculated for each participant from the six stress assessments. The diagnosis of HDP was abstracted from the medical record and was defined as the presence of gestational hypertension after 20 weeks of pregnancy and/or preeclampsia. The association between composite stress and HDP was determined using binary logistic regression. Inflammation, using the six inflammatory biomarkers, was tested as a potential mediator between stress and HDP.

Results Participants with higher composite stress scores were more likely to develop HDP (odds ratio [OR]: 1.50, 95% confidence interval [CI]: 1.06–2.12). When adjusted for known risk modifiers, including maternal age, race/ethnicity, parity, pre-pregnancy body mass index, diabetes, chronic hypertension, and smoking during pregnancy, the risk remained unchanged (OR: 1.50, 95% CI: 1.03–2.20). No mediation effect by inflammation was observed.

Conclusion Independent of known risk factors, women exposed to greater composite stress burden across the life course are at increased risk of developing HDP.

Key Points
Simulations of Deliveries of SARS-CoV-2 Positive Pregnant Women and Their Newborn Babies: Plan to Implement a Complex and Ever-Changing Protocol
Authors: Rastogi Shantanu
Published: July 2020

Management of severe acute respiratory Syndrome corona virus-2 (SARS-CoV-2) infected pregnant women at time of delivery presents a unique challenge. The variability in the timing and the method of delivery, ranging from normal vaginal delivery to an emergent cesarean section, adds complexity to the role of the health care providers in the medical care of the patient and in the interactions, they have with other providers. These variations are further influenced by the availability of isolation rooms in the facility and adequacy of personal protective equipment. The protocols already set in place can be further challenged when the facility reaches its capacity to manage the patients.

To fulfill the goal of providing adequate management to the SARS-CoV-2 infected pregnant women and their infants, avoid variation from suggested guidelines, and decrease risk of exposure of the health care workers, the health care provider team needs to review the variations regularly. While familiarity can be achieved by reviewing the guidelines, clinical case simulations provide a more hands-on approach.

Using case-based simulations and current guidance from the Center for Disease Control, American Academy of Pediatrics, and recent reviews, we discuss a management guideline developed at our institution to facilitate provision of care to SARS-CoV-2 infected pregnant women during delivery and to their infants, while protecting health care providers from exposure, and in keeping with the local facility logistics.

Key Points
A Comparison of Central Anatomic Single-Bundle Reconstruction and Anatomic Double-Bundle Reconstruction in Anteroposterior and Rotational Knee Stability: Intraoperative Biomechanical Evaluation
Authors: Ikuta Yasunari , Nakamae Atsuo , Shimizu Ryo , Ishikawa Masakazu , Nakasa Tomoyuki , Ochi Mitsuo , Adachi Nobuo
Published: July 2020

Postoperative anterior and rotational stability are still controversial when compared with single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. This study aimed to compare the central anatomical SB and anatomical DB ACL reconstruction in intraoperative knee kinematics during continuous knee flexion-extension. A total of 34 patients who underwent ACL reconstruction using the hamstring tendon were evaluated intraoperatively before and immediately after ACL reconstruction using OrthoPilot ACL Navigation System Version 3.0. The patients were prospectively randomized into the central anatomical SB (17 knees) and the anatomical DB reconstruction (17 knees) groups. The tibial translation and rotation were continuously measured during knee flexion-extension under conventional knee motion, anterior tibial load (100N), and internal-external torque (3 N·m). The anterior tibial translation and total range of tibial rotation were calculated from the measurement values from 20 to 50 degrees at each 5-degree point. The anterior tibial translation (p = 0.59; two-factor repeated measures analysis of variance; η
2G = 0.0077) and total range of tibial rotation (p = 0.95; η
2G = 0.0001) at each knee flexion angle showed no significant difference between the central anatomical SB and anatomical DB reconstruction groups. It is suggested that the central anatomical SB reconstruction is comparable with the anatomical DB reconstruction in biomechanical anteroposterior and rotational knee stability at time 0.
Comparison of Nasal CPAP versus Bi-level CPAP in Transient Tachypnea of the Newborn: A Randomized Trial
Authors: Özer Bekmez Buse , Dizdar Evrim Alyamaç , Büyüktiryaki Mehmet , Sari Fatmanur , Uraş Nurdan , Canpolat Fuat Emre , Oğuz Şerife Suna
Published: July 2020

Objective The optimal noninvasive ventilation (NIV) modality in the treatment of transient tachypnea of the newborn (TTN) is still unknown. The aim of this study was to compare nasal continuous positive airway pressure (NCPAP) versus bi-level CPAP in the treatment of TTN.

Study Design This was a prospective randomized study that was conducted in a tertiary level neonatal intensive care unit of Zekai Tahir Burak Women's Health Education and Research Hospital during the 1-year period between April 2017 and March 2018. The study included infants at ≥34 gestational weeks and birth weight ≥2,000 g who were diagnosed with TTN. The patients were randomized to either NCPAP or bi-level CPAP groups as initial respiratory support. The primary outcome was the rate of NIV failure.

Results A total of 151 infants were incorporated into the study. The intubation rate was significantly higher in the NCPAP group (15/75) compared with the bi-level CPAP group (6/76) (p = 0.032). There was a significant decrease in the level of pCO2 at the 12 (60.7 ± 6.7 vs. 66.3 ± 8.8, p = 0.017) and 24 (50 ± 8 vs. 53 ± 10, p = 0.028) hours of NIV in the bi-level CPAP group compared with the NCPAP group. Duration of NIV, total respiratory support, hospital stay, and the incidence of pneumothorax were similar between the groups.

Conclusion Bi-level CPAP reduced the rate of NIV failure and pCO2 levels at the 12 and 24 hours in late preterm and term infants with a diagnosis of TTN.

Key Points
Clinical Implications of SARS-CoV-2 Infection in the Viable Preterm Period
Authors: Gulersen Moti , Blitz Matthew J. , Rochelson Burton , Nimaroff Michael , Shan Weiwei , Bornstein Eran
Published: July 2020

Objective This study aimed to determine the rate of preterm birth (PTB) during hospitalization among women diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between 23 and 37 weeks of gestation and whether this rate differs by gestational age at diagnosis of infection.

Study Design Retrospective, cross-sectional study of all women diagnosed with SARS-CoV-2 infection between 23 and 37 weeks of gestation within a large integrated health system from March 13 to April 24, 2020. Cases with severe fetal structural malformations detected prior to infection were excluded. Women were stratified into two groups based on gestational age at diagnosis: early preterm (230/7 to 336/7 weeks) versus late preterm (34 to 366/7 weeks). We compared the rate of PTB during hospitalization with infection between the two groups. Statistical analysis included use of Wilcoxon rank sum and Fisher exact tests, as well as a multivariable logistic regression. Statistical significance was defined as a p-value <0.05.

Results Of the 65 patients included, 36 (53.7%) were diagnosed in the early preterm period and 29 (46.3%) were diagnosed in the late preterm period. Baseline demographics were similar between groups. The rate of PTB during hospitalization with infection was significantly lower among women diagnosed in the early preterm period compared with late preterm (7/36 [19.4%] vs. 18/29 [62%], p-value = 0.001). Of the 25 patients who delivered during hospitalization with infection, the majority were indicated deliveries (64%, 16/25). There were no deliveries <33 weeks of gestation for worsening coronavirus disease 2019 and severity of disease did not alter the likelihood of delivery during hospitalization with SARS-CoV-2 infection (adjusted odds ratio [aOR]: 0.64; 95% confidence interval [CI]: 0.24–1.59). Increased maternal age was associated with a lower likelihood of delivery during hospitalization with SARS-CoV-2 infection (aOR: 0.77; 95% CI: 0.58–0.96), while later gestational age at diagnosis of infection was associated with a higher likelihood of delivery during hospitalization (aOR: 2.9; 95% CI: 1.67–8.09).

Conclusion The likelihood of PTB during hospitalization with SARS-CoV-2 infection is significantly lower among women diagnosed in the early preterm period compared with late preterm. Most women with SARS-CoV-2 infection in the early preterm period recovered and were discharged home. The majority of PTB were indicated and not due to spontaneous preterm labor.

Key Points
A note on the continuity for Caputo fractional stochastic differential equations
Authors: Wang Wenya , Cheng Shuilin , Guo Zhongkai , Yan Xingjie
Published: July 2020

The first aim of this paper is to establish the well-posedness for a type of Caputo fractional stochastic differential equations, and we obtain the global existence and uniqueness of solutions under some conditions consistent with the classic (integer order) stochastic differential equations. The second aim is that we consider the continuity of solutions on the fractional order of those equations.
Competing local and global interactions in social dynamics: How important is the friendship network?
Authors: Jędrzejewski Arkadiusz , Nowak Bartłomiej , Abramiuk Angelika , Sznajd-Weron Katarzyna
Published: July 2020

Motivated by the empirical study that identifies a correlation between particular social responses and different interaction ranges, we study the q-voter model with various combinations of local and global sources of conformity and anticonformity. The models are investigated by means of the pair approximation and Monte Carlo simulations on Watts–Strogatz and Barabási–Albert networks. We show that within the model with local conformity and global anticonformity, the agreement in the system is the most difficult one to achieve and the role of the network structure is the most significant. Interestingly, the model with swapped interaction ranges, namely, with global conformity and local anticonformity, becomes almost insensitive to the changes in the network structure. The obtained results may have far reaching consequences for marketing strategies conducted via social media channels.
Comparative study for intermediate crystal size of NaI(Tl) scintillation detector
Authors: Singh Inderjeet , Singh Bhajan , Sandhu B. S. , Sabharwal Arvind D.
Published: July 2020

The distinctive features of a well-known NaI(Tl) scintillation detector, by virtue of its crystal size, are experimentally investigated by observing changes in parameters such as intrinsic efficiency (εi), photo-peak efficiency (εp), resolution, and response function to incident gamma photon energy. This study provides a better understanding for the choice of crystal size of the scintillation detector in Compton scattering experiments. The response function of the NaI(Tl) detector is in the form of an inverse matrix focusing on the retort of the crystal when gamma photons are incident upon it. The response function of the NaI(Tl) detector depends upon the distance between the source and the detector, composition of the material for the crystal itself, photo-fraction, solid angle, incident gamma energy, and geometry of the experimental setup. The factors responsible for broadening of full energy and backscattered peaks are discussed for present investigations. The observed results indicate that the resolution of the detector varies with the incident energy of gamma radiation, and it also depends upon the size of the crystal of the detector. Statistical fluctuations related with the scintillation mechanism are found to be responsible for broadening of instrumental line width (photo-peak). The signal-to-noise ratio and photo-fraction for different crystal sizes of the scintillation detector corrected for efficiency of the detector are also discussed.
An advanced 2ω method enabling thermal conductivity measurement for various sample thicknesses: From thin films to bulk materials
Authors: Mitarai Kosuke , Okuhata Ryo , Chikada Jinichiro , Kaneko Tatsuya , Uematsu Yuto , Komatsubara Yuki , Ishibe Takafumi , Nakamura Yoshiaki
Published: July 2020

We developed an advanced 2ω method for thermal conductivity (κ) measurements that is also applicable to samples with a wide range of thicknesses, to which the flash method cannot be applied. The conventional 2ω method, which features a simple setup combined with thermoreflectance, is a κ measurement method for thin films on substrates. However, it is difficult to apply this method to bulk substrate samples without films because of the interfacial thermal resistance between the transducer metal film and the substrate. In the advanced 2ω method, the interfacial thermal resistance becomes negligible due to the coating of a bulk sample with a high-thermal-resistance film. We measured the κ values of various bulk samples (Si, Ge, fused quartz, and TiO2). Moreover, the κ value of thin (0.3-mm) bulk Si substrates, which is difficult to measure using the conventional flash method for bulk materials because of the high thermal diffusivity, could be measured. This study demonstrates that the range of sample thickness for the 2ω method is extended from thin films to bulk materials.
Intrinsic and extrinsic conduction contributions at nominally neutral domain walls in hexagonal manganites
Authors: Schultheiß J. , Schaab J. , Småbråten D. R. , Skjærvø S. H. , Bourret E. , Yan Z. , Selbach S. M. , Meier D.
Published: July 2020

Conductive and electrostatic atomic force microscopy (cAFM and EFM) are used to investigate the electric conduction at nominally neutral domain walls in hexagonal manganites. The EFM measurements reveal a propensity of mobile charge carriers to accumulate at the nominally neutral domain walls in ErMnO3, which is corroborated by cAFM scans showing locally enhanced direct current conductance. Our findings are explained based on the established segregation enthalpy profiles for oxygen vacancies and interstitials, providing a microscopic model for previous, seemingly disconnected observations ranging from insulating to conducting behavior. In addition, we observe variations in conductance between different nominally neutral walls that we attribute to deviations from the ideal charge-neutral structure within the bulk, leading to a superposition of extrinsic and intrinsic contributions. Our study clarifies the complex transport properties at nominally neutral domain walls in hexagonal manganites and establishes the possibility to tune their electronic response based on oxidation conditions, opening the door for domain-wall-based sensor technology.
How many photons does it take to form an image?
Authors: Johnson Steven D. , Moreau Paul-Antoine , Gregory Thomas , Padgett Miles J.
Published: July 2020

If a picture tells a thousand words, then we might ask ourselves how many photons does it take to form a picture? In terms of the transmission of the picture information, then the multiple degrees of freedom (e.g., wavelength, polarization, and spatial mode) of the photon mean that high amounts of information can be encoded such that the many pixel values of an image can, in principle, be communicated by a single photon. However, the number of photons required to transmit the image information is not necessarily, at least technically, the same as the number of photons required to image an object. Therefore, another equally important question is how many photons does it take to measure an unknown image?
Improving the sensitivity of galloping energy harvesters to flow fluctuations
Authors: Alhadidi Ali H. , Alhussein Hussam , Daqaq Mohammed F.
Published: July 2020

Small scale flow energy harvesters are designed to operate at low elevations where surface effects cause significant flow velocity variations. To harness flow energy efficiently in such environments, the harvester must be very sensitive to flow fluctuations. In particular, the rise time of the harvester to the steady-state value must be short. This Letter proposes a method to reduce the rise time of galloping flow energy harvesters by passively manipulating the flow near the trailing edge. To this end, the rear face of the square prism typically used in galloping energy harvesting is augmented with Y-shaped fins of different lengths and fork angles. The addition of the fins is shown to significantly increase the rate at which the magnitude of the normal force coefficient grows with the angle of attack. This, in turn, can reduce the rise time of the harvester by as much as 75% when compared to the finless square prism. The addition of the fins has no detrimental influence on the steady-state performance of the harvester. On the contrary, the steady-state voltage of the harvester can also be improved for some fin geometries.
Chaotic motion due to lateral Casimir forces during nonlinear actuation dynamics
Authors: Tajik F. , Masoudi A. A. , Sedighi M. , Palasantzas G.
Published: July 2020

We investigated here the influence of the lateral Casimir force on the dynamical actuation of devices with interacting materials covering a broad range of optical properties ranging from poor to good conductors, such as, for example, nitrogen doped SiC and Au, respectively. The conservative actuating system shows a central heteroclinic orbit surrounded by a finite number of homoclinic orbits, because at higher periods, an increased lateral Casimir force will be necessary to counterbalance the restoring force. As a result, the conservative system reaches stable operation sooner for the higher conductivity materials (Au–Au), indicating the significant impact of the material optical properties on the lateral Casimir force. Furthermore, for the non-conservative driven systems, the decrement of the Melnikov parameter α leads to a faster disappearance of the satellite homoclinic orbits in the Poincaré portraits, followed by a strong shrinkage of the central heteroclinic orbit toward unstable chaotic motion. The latter is more pronounced for the lower conductivity materials since comparison shows the Au–Au system to be significantly more stable than the SiC–SiC system. Therefore, in actuating systems where the lateral Casimir force could play a significant role, the higher conductivity materials appear to be a better choice to ensure stable operation against a chaotic motion.
Underlayer effect on the soft magnetic, high frequency, and magnetostrictive properties of FeGa thin films
Authors: Acosta Adrian , Fitzell Kevin , Schneider Joseph D. , Dong Cunzheng , Yao Zhi , Sheil Ryan , Wang Yuanxun Ethan , Carman Gregory P. , Sun Nian X. , Chang Jane P.
Published: July 2020

The soft magnetic, microstructural, and magnetostrictive properties of Fe81Ga19 (FeGa) film sputter deposited onto 2.5-nm Ta, Cu, and Ni80Fe20 (NiFe) underlayers were investigated. The films deposited with an underlayer showed increased in-plane uniaxial anisotropy and a decrease in in-plane coercivity. The smallest coercivity was observed in FeGa deposited with a NiFe underlayer at 15 Oe, compared to 84 Oe for films deposited directly on Si. In addition, an effective Gilbert damping coefficient (αeff) as low as 0.044 was achieved for a 100-nm FeGa film with a NiFe underlayer. The coercivity and αeff were shown to decrease further as a function of FeGa film thickness. The FeGa films were also able to retain or increase their saturation magnetostriction when deposited on an underlayer. This enhancement is attributable to the impact of the underlayer to promote an increased (110) film texture and smaller grain size, which is correlated to the lattice match of the underlayer of the sputtered FeGa film. Among the underlayers studied, NiFe promoted the best enhancement in the soft magnetic properties for FeGa thin films, making it an attractive material for both strain-mediated magnetoelectric and microwave device applications.
Flow-induced vibration of inherently nonlinear structures with applications in energy harvesting
Authors: Seyed-Aghazadeh B. , Samandari H. , Dulac S.
Published: July 2020

This paper proposes a novel design for a flow-induced vibration-based energy harvester, consisting of an elastic L-shaped beam, with an inherent nonlinearity in its structural stiffness as an alternative to the classical cantilever beam used in conventional fluidic energy harvester designs. The L-shaped beam supports a prism at its tip and undergoes large-amplitude galloping oscillations. The results from wind tunnel experiments show that by replacing a conventional linear structure that supports the prism with a nonlinear one, the high frequency flow components, shed from the tip prism, were capable of exciting the oscillations of the structure at higher harmonics of the main resonance, thus enhancing the power density of the energy harvester. As a result of improved power density values, the proposed harvester design holds great potential to be used as advanced space-efficient energy harvesters.
Comparing Fourier transform infrared spectroscopy results with photocurrent measurements for Ge-on-Si PIN photodetectors with and without Al nanoantennas
Authors: Augel Lion , Fischer Inga A. , Gollhofer Martin , Oehme Michael , Schulze Jörg
Published: July 2020

Plasmonic and nanophotonic structures have been used to enhance the performance of photonic devices through the control and manipulation of photonic energy. Characterization of such devices typically requires the fabrication of contacting structures followed by stepwise spectral illumination and data recording. The acquisition of reflectance and transmittance spectra with Fourier transform infrared spectroscopy (FTIR) is—in contrast—a contactless and faster process. Since FTIR measurements take into account substrate absorption, which does not contribute to photocurrent, the two measurement approaches cannot be compared without further data processing. Here, we present a strategy to separate substrate absorption from absorption processes within the device layers in order to predict device performance from FTIR measurements. We apply our strategy to Ge-on-Si planar photodetectors with and without plasmonic structures.
Machine learning 5d-level centroid shift of Ce3+ inorganic phosphors
Authors: Zhuo Ya , Hariyani Shruti , You Shihai , Dorenbos Pieter , Brgoch Jakoah
Published: July 2020

Information on the 5d level centroid shift (ɛc) of rare-earth ions is critical for determining the chemical shift and the Coulomb repulsion parameter as well as predicting the luminescence and thermal response of rare-earth substituted inorganic phosphors. The magnitude of ɛc depends on the binding strength between the rare-earth ion and its coordinating ligands, which is difficult to quantify a priori and makes phosphor design particularly challenging. In this work, a tree-based ensemble learning algorithm employing extreme gradient boosting is trained to predict ɛc by analyzing the optical properties of 160 Ce3+ substituted inorganic phosphors. The experimentally measured ɛc of these compounds was featurized using the materials' relative permittivity (ɛr), average electronegativity, average polarizability, and local geometry. Because the number of reported ɛr values is limited, it was necessary to utilize a predicted relative permittivity (ɛr,SVR) obtained from a support vector regressor trained on data from ∼2800 density functional theory calculations. The remaining features were compiled from open-source databases and by analyzing the rare-earth coordination environment from each Crystallographic Information File. The resulting ensemble model could reliably estimate ɛc and provide insight into the optical properties of Ce3+-activated inorganic phosphors.
Study of SPDC spectra to reveal temperature dependences for optical-terahertz biphotons
Authors: Novikova T. I. , Kuznetsov K. A. , Leontyev A. A. , Kitaeva G. Kh.
Published: July 2020

Frequency-angular distributions of optical signals generated via spontaneous parametric downconversion with the Stokes idler frequency shifts 0.2–5 THz are studied simultaneously with the same distributions in the anti-Stokes range while the nonlinear Mg:LiNbO3 crystal is cooled from 300 K to 4.2 K. The temperature dependencies of the angular distributions at fixed idler frequencies are analyzed using a theoretical Klyshko–Kirchhoff approach with account of thermal field fluctuations and inherent crystal absorption at terahertz frequencies. Although all the measurements are performed in the optical range, we demonstrate how such analysis enables to predict the temperature behavior of the total number of spontaneous parametric downconversion-generated idler photons in the terahertz range, the temperature variation of the optical-terahertz biphoton function, and to study the contributions of classical thermal and pure quantum field fluctuations to parameters of biphotons. It is shown that the temperature-induced growth of the numbers of signal and idler photons and their non-normalized correlation function is provided by overwhelming increase in classical fluctuations, while the pure quantum contributions to these parameters are not so sensitive to the crystal temperature.
Spectra of CO2–N2 dimer in the 4.2 μm region: Symmetry breaking of the intramolecular CO2 bend, the intermolecular bend, and higher K-values for the fundamental
Authors: Barclay A. J. , McKellar A. R. W. , Moazzen-Ahmadi N.
Published: July 2020

Infrared spectra of the CO2–N2 dimer are observed in the carbon dioxide ν3 asymmetric stretch region (≈2350 cm−1) using a tunable infrared optical parametric oscillator to probe a pulsed slit jet supersonic expansion. Previous results for the b-type fundamental band are extended to higher values of Ka. An a-type combination band involving the lowest in-plane intermolecular bending mode is observed. This yields a value of 21.4 cm−1 and represents the first experimental determination of an intermolecular mode for CO2–N2. This intermolecular frequency is at odds with the value of 45.9 cm−1 obtained from a recent 4D intermolecular potential energy surface. In addition, two weak bands near 2337 cm−1 are assigned to the CO2 hot band transition (v1, v2l2, v3) = (0111) ← (0110). They yield a value of 2.307 cm−1 for the splitting of the degenerate CO2 ν2 bend into in-plane and out-of-plane components due to the presence of the nearby N2. The in-plane mode lies at a lower energy relative to the out-of-plane mode.
Coherent high-power RF wakefield generation by electron bunch trains in a metamaterial structure
Authors: Lu Xueying , Picard Julian F. , Shapiro Michael A. , Mastovsky Ivan , Temkin Richard J. , Conde Manoel , Power John G. , Shao Jiahang , Wisniewski Eric E. , Peng Maomao , Ha Gwanghui , Seok Jimin , Doran Scott , Jing Chunguang
Published: July 2020

We present an experimental study of coherent high-power wakefield generation in a metamaterial (MTM) structure at 11.7 GHz by 65 MeV electron bunch trains at the Argonne Wakefield Accelerator (AWA), following a previous experiment, the Stage-I experiment, at the AWA. Both the Stage-II experiment, reported in this paper, and the Stage-I experiment were conducted using MTM structures, which are all-metal periodic structures with the period being much smaller than the wavelength. Differences between the two experiments include (1) structure length (Stage-I 8 cm and Stage-II 20 cm); (2) number of bunches used to excite the structure (Stage-I with two bunches, up to 85 nC of total charge; Stage-II with eight bunches, up to 224 nC of total charge); and (3) highest peak power measured (Stage-I 80 MW in a 2 ns pulse and Stage-II 380 MW in a 10 ns pulse). High-power radio frequency pulses were generated by reversed Cherenkov radiation of the electron beam due to the negative group velocity in the MTM structures. Because the radiation is coherent, a train of bunches with a proper spacing can build up to achieve a high peak power. The observed output power levels are very promising for future applications in direct collinear wakefield acceleration or in transfer to a second accelerator for two-beam acceleration.
Interface modification effect on the performance of CsxFA1−xPbIyBr3−y perovskite solar cells fabricated by evaporation/spray-coating method
Authors: Yu Xinxin , Yan Xue , Xiao Junyan , Ku Zhiliang , Zhong Jie , Li Wei , Huang Fuzhi , Peng Yong , Cheng Yi-Bing
Published: July 2020

In this study, high quality CsxFA1−xPbIyBr3−y perovskite thin films were successfully fabricated by an evaporation/spray-coating hybrid deposition method. In this method, CsI and PbI2 were first deposited via thermal evaporation, and then FAI/FABr mixed solution was sprayed on the CsI/PbI2 substrate to form the CsxFA1−xPbIyBr3−y film. As confirmed by x-ray diffraction, scanning electron microscopy, and atomic force microscopy, a perovskite film with full surface coverage and small surface roughness was obtained. Then, the effect of interface modification materials on the performance of perovskite solar cells (PSCs) was investigated: the devices with the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interlayer incorporated via vacuum evaporation deposition between SnO2 and perovskite showed remarkably higher performance than those with the C60 interlayer, which was attributed to enhanced charge extraction and reduced recombination at the SnO2/PCBM/perovskite interface. As a result, a high power conversion efficiency (PCE) of 18.21% was obtained for the 0.16 cm2 device. To the best of our knowledge, it is the highest efficiency of CsxFA1−xPbIyBr3−y based PSCs fabricated by the spray technique. Furthermore, we fabricated mini-modules with the size of 5 × 5 cm2 and achieved a PCE of 14.7%.
Antimonene nanosheets fabricated by laser irradiation technique with outstanding nonlinear absorption responses
Authors: Wu Jinqiang , Wei Yi , Shen Weili , Xiong Yunhai , Lin Cheng , Gao Yujie , AL-Ammari Abdulrahman , Liu Kai , Ma Teng , Chen Jun , Zeng Haibo
Published: July 2020

Antimonene nanosheets are obtained by laser irradiation of antimony powder in isopropyl alcohol and the thicknesses of antimonene nanosheets are around 4–12 nm. The nonlinear optical responses of the samples are probed by a z-scan measurement employing a nanosecond laser pulse. The competition between saturable absorption and reverse saturable absorption at 532 nm is confirmed in the dispersion of antimonene nanosheets. The optical limiting (OL) onset fluence (FON) and the optical limiting threshold (FOL) of the antimonene are 0.162 J/cm2 and 1.37 J/cm2, respectively. Our finding not only provides an approach feasible for the fabrication of uniform antimonene nanosheets in ambient conditions but also manifests that antimonene has excellent optical responses making it promising for OL device applications.
Early effects of salt stress on the physiological and oxidative status of the halophyte Lobularia maritima
Authors: Ben Hsouna Anis , Ghneim-Herrera Thaura , Ben Romdhane Walid , Dabbous Amira , Ben Saad Rania , Brini Faical , Abdelly Chedly , Ben Hamed Karim
Published: July 2020

Soil salinity is an abiotic stress that reduces agricultural productivity. For decades, halophytes have been studied to elucidate the physiological and biochemical processes involved in alleviating cellular ionic imbalance and conferring salt tolerance. Recently, several interesting genes with proven influence on salt tolerance were isolated from the Mediterranean halophyte Lobularia maritima (L.) Desv. A better understanding of salt response in this species is needed to exploit its potential as a source of stress-related genes. We report the characterisation of L. maritima’s response to increasing NaCl concentrations (100–400 mM) at the physiological, biochemical and molecular levels. L. maritima growth was unaffected by salinity up to 100 mM NaCl and it was able to survive at 400 mM NaCl without exhibiting visual symptoms of damage. Lobularia maritima showed a Na+ and K+ accumulation pattern typical of a salt-includer halophyte, with higher contents of Na+ in the leaves and K+ in the roots of salt-treated plants. The expression profiles of NHX1, SOS1, HKT1, KT1 and VHA-E1 in salt-treated plants matched this Na+ and K+ accumulation pattern, suggesting an important role for these transporters in the regulation of ion homeostasis in leaves and roots of L. maritima. A concomitant stimulation in phenolic biosynthesis and antioxidant enzyme activity was observed under moderate salinity, suggesting a potential link between the production of polyphenolic antioxidants and protection against salt stress in L. maritima. Our findings indicate that the halophyte L. maritima can rapidly develop physiological and antioxidant mechanisms to adapt to salt and manage oxidative stress.
The role of soil temperature and seed dormancy in the creation and maintenance of persistent seed banks of Nassella trichotoma (serrated tussock) on the Northern Tablelands of New South Wales
Authors: Ruttledge Annemieke , Whalley Ralph D. B. , Falzon Gregory , Backhouse David , Sindel Brian M.
Published: July 2020

A large and persistent soil seed bank characterises many important grass weeds, including Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), a major weed in Australia and other countries. In the present study we examined the effects of constant and alternating temperatures in regulating primary and secondary dormancy and the creation and maintenance of its soil seed bank in northern NSW, Australia. One-month-old seeds were stored at 4, 25°C, 40/10°C and 40°C, in a laboratory, and germination tests were conducted every two weeks. Few seeds germinated following storage at 4°C, compared with seeds stored at 25°C, 40/10°C and 40°C. Nylon bags containing freshly harvested seeds were buried among N. trichotoma stands in early summer, and germination tests conducted following exhumation after each season over the next 12 months. Seeds buried over summer and summer plus autumn had higher germination than seeds buried over summer plus autumn plus winter, but germination increased again in the subsequent spring. Seeds stored for zero, three, six and 12 months at laboratory temperatures were placed on a thermogradient plate with 81 temperature combinations, followed by incubation at constant 25°C of un-germinated seeds. Constant high or low temperatures prolonged primary dormancy or induced secondary dormancy whereas alternating temperatures tended to break dormancy. Few temperature combinations resulted in more than 80% germination.