bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioral Auditory Processing in Children and Young Adults with Autism Spectrum Disorder
Authors: Schafer Erin C. , Mathews Lauren , Gopal Kamakshi , Canale Emilee , Creech Avery , Manning Jacy , Kaiser Kara
Published: December 2020

Abstract Background Auditory-processing deficits are common in children and adults who are diagnosed with autism spectrum disorder (ASD). These deficits are evident across multiple domains as exhibited by the results from subjective questionnaires from parents,
teachers, and individuals with ASD and from behavioral auditory-processing testing. Purpose Few studies compare subjective and behavioral performance of adults and children diagnosed with ASD using commercially available tests of auditory processing. The primary goal of the
present study is to compare the performance of adults and children with ASD to age-matched, neurotypical peers. The secondary goal is to examine the effect of age on auditory-processing performance in individuals with ASD relative to age-matched peers. Research Design A four-group,
quasi-experimental design with repeated measures was used in this study. Study Sample Forty-two adults and children were separated into four groups of participants: (1) 10 children with ASD ages 14 years or younger; (2) 10 age-matched, neurotypical children; (3) 11 adolescents
and young adults with ASD ages 16 years and older; and (4) 11 age-matched, neurotypical adolescents or young adults. Data Collection and Analysis Data from each participant were collected in one test session. Data were analyzed with analysis of variance (ANOVA), repeated measures
ANOVA, or nonparametric analyses. Effect sizes were calculated to compare performance between those with ASD and those who were neurotypical within each age group. Results Across all the questionnaires and the majority of the behavioral test measures, participants with ASD
had significantly poorer ratings or auditory-processing performance than age-matched, neurotypical peers. Adults had more favorable performance than children on several of the test measures. Medium to large effect sizes corroborated the significant results. Conclusion Overall,
the questionnaires and behavioral tests used in this study were sensitive to detecting auditory-processing differences between individuals diagnosed with ASD and those who are considered neurotypical. On most test measures, children performed more poorly than adults. The findings in this study
support that both children and adults with ASD exhibit auditory-processing difficulties. Appropriate school and work accommodations will be necessary to ensure appropriate access to speech in challenging environments.
Speech Recognition in Noise in Single-Sided Deaf Cochlear Implant Children on Using Adaptive Digital Microphone Technology
Authors: Speck I. , Müller T. , Jakob T. F. , Wiebe K. , Aschendorff A. , Arndt S. , Wesarg T. , Hassepass F.
Published: December 2020

Abstract Background Previous research demonstrated benefits of adaptive digital microphone technologies (ADMTs) in adults with single-sided deafness (SSD) having a cochlear implant (CI). Children with SSD are especially affected by background noise because of
their noise exposure in kindergarten and school. Purpose This article aims to evaluate possible effects of ADMT on speech recognition in background noise in children with SSD who use a CI. Study Sample Ten children between 5 and 11 years of age were included.
Data Collection and Analysis Speech recognition in noise was assessed for one frontal distant and two lateral speakers. The speech stimulus was presented at a speech level of 65 dB(A) and noise at a level of 55 dB(A). For the presentation condition with one frontal
speaker, four listening conditions were assessed: (1) normal-hearing (NH) ear and CI turned off; (2) NH ear and CI; (3) NH ear and CI with ADMT; and (4) NH ear with ADMT and CI. Listening conditions (2) to (4) were also tested for each lateral speaker. The frontal speaker was positioned directly
in front of the participant, whereas the lateral speakers were positioned at angles of 90 degrees and ‐90 degrees to the participant's head. Results Children with SSD who use a CI significantly benefit from the application of ADMT in speech recognition
in noise for frontal distant and for lateral speakers. Speech recognition improved significantly with ADMT at the CI and the NH ears. Conclusion Application of ADMT significantly improves speech recognition in noise in children with SSD who use a CI and can therefore be highly
recommended. The decision of whether to apply ADMT at the CI NH ear or bilaterally should be made for each child individually.
Intelligibility of British- and American-Accented Sentences for American Younger and Older Listeners With and Without Hearing Loss
Authors: Schilaty Sadie , Ferguson Sarah Hargus , Morgan Shae D. , Champougny Caroline
Published: December 2020

Abstract Background Older adults with hearing loss often report difficulty understanding British-accented speech, such as in television or movies, after having understood such speech in the past. A few studies have examined the intelligibility of various United
States regional and non-U.S. varieties of English for American listeners, but only for young adults with normal hearing. Purpose This preliminary study sought to determine whether British-accented sentences were less intelligible than American-accented sentences for American
younger and older adults with normal hearing and for older adults with hearing loss. Research Design A mixed-effects design, with talker accent and listening condition as within-subjects factors and listener group as a between-subjects factor. Study Sample Three
listener groups consisting of 16 young adults with normal hearing, 15 older adults with essentially normal hearing, and 22 older adults with sloping sensorineural hearing loss. Data Collection and Analysis Sentences produced by one General American English speaker and one British
English speaker were presented to listeners at 70 dB sound pressure level in quiet and in babble. Signal-to-noise ratios for the latter varied among the listener groups. Responses were typed into a textbox and saved on each trial. Effects of accent, listening condition, and listener
group were assessed using linear mixed-effects models. Results American- and British-accented sentences were equally intelligible in quiet, but intelligibility in noise was lower for British-accented sentences than American-accented sentences. These intelligibility differences
were similar for all three groups. Conclusion British-accented sentences were less intelligible than those produced by an American talker, but only in noise.
Social Representation of “Hearing Loss” Among People with Hearing Loss: An Exploratory Cross-Cultural Study
Authors: Chundu Srikanth , Manchaiah Vinaya , Han Woojae , Thammaiah Spoorthi , Ratinaud Pierre , Allen Peter M.
Published: December 2020

Abstract Background Hearing loss can have an effect on the physical, psychosocial, and cognitive wellbeing of an individual. Despite the research on attitudes and stigma associated with hearing loss, people with hearing loss (PHL) continue to delay seeking help.
Thus, it is vital to look at alternative theories which have been successfully used in disability research to better understand how PHL perceive hearing loss. Purpose The aim of the current exploratory study was to examine the social representation (SR) of “hearing loss”
in PHL in India, Republic of Korea (ROK), United Kingdom (UK), and the United States (US). Research Design The study used a cross-sectional survey design. Study Sample In this study, 424 participants were recruited using a consecutive sampling method in four
countries (India, Republic of Korea, United Kingdom, and United States). Data Collection and Analysis Data collection was conducted using a questionnaire. Data were analyzed using content analysis, similarities analysis, prototypical analysis, and chi-square analysis. Results The
free associations of the PHL were grouped into 37 categories. The most commonly reported categories were communication difficulties, negative mental state, aging, assessment and management, causes of hearing loss, hearing ability or disability, hearing instruments, and symptoms of
hearing loss. Similarities analysis and prototypical analysis highlighted two main negative categories (negative mental state and communication difficulties) which form the central elements of SR of hearing loss. PHL associated hearing loss mainly as a negative phenomenon, but with
some positive and neutral aspects. Respondents from ROK reported a greater number of neutral associations compared with other countries. There were cross-cultural similarities and differences in terms of PHL's SR of hearing loss, but there were more similarities than differences. Conclusion The
study provides an insight into how PHL collectively view their “hearing loss” and helps to develop our understanding of the influence of culture on the SR of “hearing loss.” The results will aid the development of culturally appropriate public education campaigns, marketing
material, and appropriate rehabilitation for PHL.
Comparison of In-Situ and Retrospective Self-Reports on Assessing Hearing Aid Outcomes
Authors: Wu Yu-Hsiang , Stangl Elizabeth , Chipara Octav , Gudjonsdottir Anna , Oleson Jacob , Bentler Ruth
Published: December 2020

Abstract Background Ecological momentary assessment (EMA) is a methodology involving repeated surveys to collect in-situ self-reports that describe respondents' current or recent experiences. Audiology literature comparing in-situ and retrospective self-reports
is scarce. Purpose To compare the sensitivity of in-situ and retrospective self-reports in detecting the outcome difference between hearing aid technologies, and to determine the association between in-situ and retrospective self-reports. Research Design An
observational study. Study Sample Thirty-nine older adults with hearing loss. Data Collection and Analysis The study was part of a larger clinical trial that compared the outcomes of a prototype hearing aid (denoted as HA1) and a commercially available device
(HA2). In each trial condition, participants wore hearing aids for 4 weeks. Outcomes were measured using EMA and retrospective questionnaires. To ensure that the outcome data could be directly compared, the Glasgow Hearing Aid Benefit Profile was administered as an in-situ self-report (denoted
as EMA-GHABP) and as a retrospective questionnaire (retro-GHABP). Linear mixed models were used to determine if the EMA- and retro-GHABP could detect the outcome difference between HA1 and HA2. Correlation analyses were used to examine the association between EMA- and retro-GHABP. Results For
the EMA-GHABP, HA2 had significantly higher (better) scores than HA1 in the GHABP subscales of benefit, residual disability, and satisfaction (p = 0.029‐0.0015). In contrast, the difference in the retro-GHABP score between HA1 and HA2 was significant only in the
satisfaction subscale (p = 0.0004). The correlations between the EMA- and retro-GHABP were significant in all subscales (p = 0.0004 to <0.0001). The strength of the association ranged from weak to moderate (r = 0.28‐0.58).
Finally, the exit interview indicated that 29 participants (74.4%) preferred HA2 over HA1. Conclusion The study suggests that in-situ self-reports collected using EMA could have a higher sensitivity than retrospective questionnaires. Therefore, EMA is worth considering in clinical
trials that aim to compare the outcomes of different hearing aid technologies. The weak to moderate association between in-situ and retrospective self-reports suggests that these two types of measures assess different aspects of hearing aid outcomes.
Why Ecological Momentary Assessment Surveys Go Incomplete: When It Happens and How It Impacts Data
Authors: Wu Yu-Hsiang , Xu Jingjing , Stangl Elizabeth , Pentony Shareka , Vyas Dhruv , Chipara Octav , Gudjonsdottir Anna , Oleson Jacob , Galster Jason
Published: December 2020

Abstract Background Ecological momentary assessment (EMA) often requires respondents to complete surveys in the moment to report real-time experiences. Because EMA may seem disruptive or intrusive, respondents may not complete surveys as directed in certain circumstances.
Purpose This article aims to determine the effect of environmental characteristics on the likelihood of instances where respondents do not complete EMA surveys (referred to as survey incompletion), and to estimate the impact of survey incompletion on EMA self-report data. Research
Design An observational study. Study Sample Ten adults hearing aid (HA) users. Data Collection and Analysis Experienced, bilateral HA users were recruited and fit with study HAs. The study HAs were equipped with real-time data loggers, an algorithm
that logged the data generated by HAs (e.g., overall sound level, environment classification, and feature status including microphone mode and amount of gain reduction). The study HAs were also connected via Bluetooth to a smartphone app, which collected the real-time data logging data as
well as presented the participants with EMA surveys about their listening environments and experiences. The participants were sent out to wear the HAs and complete surveys for 1 week. Real-time data logging was triggered when participants completed surveys and when participants ignored or
snoozed surveys. Data logging data were used to estimate the effect of environmental characteristics on the likelihood of survey incompletion, and to predict participants' responses to survey questions in the instances of survey incompletion. Results Across the 10 participants,
715 surveys were completed and survey incompletion occurred 228 times. Mixed effects logistic regression models indicated that survey incompletion was more likely to happen in the environments that were less quiet and contained more speech, noise, and machine sounds, and in the environments
wherein directional microphones and noise reduction algorithms were enabled. The results of survey response prediction further indicated that the participants could have reported more challenging environments and more listening difficulty in the instances of survey incompletion. However, the
difference in the distribution of survey responses between the observed responses and the combined observed and predicted responses was small. Conclusion The present study indicates that EMA survey incompletion occurs systematically. Although survey incompletion could bias
EMA self-report data, the impact is likely to be small.
Easier to Twist than Bend: The Scope of the Bridge Formation Approach to Naphthalenophane Synthesis
Authors: Bedi Anjan , Shimon Linda J. W. , Bogoslavsky Benny , Gidron Ori
Published: December 2020

Twisting anthracene and higher acenes can alter their optical, magnetic, and electronic properties. To test the effect of twisting on the lower homologue, naphthalene, we synthesized tethered naphthalenophanes bearing alkyl bridges. Both X-ray structure and DFT calculations show that hexyl and butyl bridges induce a 6° and 12° end-to-end twist on the naphthalene unit, respectively. Attempts to increase the twisting further using shorter tethers resulted in an elimination product. Enantiomerically pure naphthalenophanes display strong chiroptical properties, which intensify with increasing twist. Attempts to induce bending, rather than twisting, using the same synthetic methodology, resulted in intermolecular dimerization, yielding macrocyclic naphthalenes. This work highlights the importance of steric hindrance in the synthesis of curved cyclophanes using the bridge formation approach.
Evaluation of Patient’s Knowledge, Attitude, and Practice of Cross-Infection Control in Dentistry during COVID-19 Pandemic
Authors: Ahmed Muhammad Adeel , Jouhar Rizwan , Adnan Samira , Ahmed Naseer , Ghazal Tuba , Adanir Necdet
Published: December 2020

Objectives The aim of this study was to evaluate the patient’s knowledge, attitude, and practice of cross-infection control in dentistry during coronavirus diseases 2019 (COVID-19).

Materials and Methods This cross-sectional observational study was conducted at Altamash Institute of Dental Medicine, Karachi from June 2020 to August 2020. A total of 775 patients participated to fill questionnaire. After scrutiny, 25 questionnaire forms were excluded due to incomplete information. Questionnaire was divided in to four sections. First section obtained patients sociodemographic information, while knowledge of patients regarding cross-infection control during COVID-19 pandemic was evaluated in second section. Similarly, the purpose of third section was to assess attitude and fourth section was designed to evaluate practice. Likert’s 3-point scale was used for registration of participant’s response. The reliability of questionnaire was assessed through Crohnbach’s α (α = 0.74). Statistical analysis was performed after entering data in to SPSS version 25. Independent t-test was used to evaluate the difference in patients’ knowledge, attitude, and practice. A p-value ≤ 0.05 was considered as statistically significant.

Results Majority of the participants agreed that COVID-19 is a highly contagious disease (631, 97%) and daily screening of staff, dental assistants, dentists, and patients is necessary (568, 75.7%) along with proper sterilization of instruments and disinfection of dental operatory (650, 86.66%). A large number of participant also agreed that proper disposal of waste is utmost important for cross-infection control (601, 80.24%) and patient's waiting area should also be marked with social distancing sign (620, 82.66%). However, when asked about the common route of COVID-19 transmission in dentistry, 341 (45.5%) participants disagreed that it is not through aerosol (water droplets) generated during dental procedures.

Conclusions Dental health professionals should take additional measures to educate dental patients on mechanism of potential spread of COVID-19 through the aerosols and droplets generated during dental procedures. They should also encourage the dental patients to be vigilant and question the cross-infection control measures practiced by the dentist to whom they go for dental treatment, and to decrease their chances of acquiring an infection during their visit to the dental office.
Prenatal and Postnatal Management of Intrauterine Pleural Effusions Associated with Nonimmune Hydrops Fetalis
Authors: Cömert Hatice S.Y. , Kader Şebnem , Osmanağaoğlu Mehmet A. , Ural Dilan A. , Yaşar Ömer F. , İmamoğlu Mustafa , Mutlu Mehmet , Sarıhan Haluk
Published: December 2020

Objective Nonimmune hydrops fetalis (NIHF) is defined as the accumulation of excess fluid in two or more body cavities in the fetus without blood incompatibility between mother and baby. We aimed to present our prenatal and postnatal management of intrauterine pleural effusions associated with NIHF.

Study Design A total of 60 patients diagnosed with NIHF with intrauterine pleural effusion were analyzed retrospectively. Gestational age of delivery or fetal demise, the intrauterine treatment procedure including extrauterine intrapartum treatment (EXIT), chest tube, and medical treatment methods in fetuses with chylothorax analyzed.

Results Thirty-nine patients (65%) were born alive between 26 and 38 weeks. A thoracoamniotic shunt was placed in one patient during the intrauterine period. Seven patients were placed bilaterally during the postnatal period, all without the umbilical cord being clamped during delivery. But 25 patients died within the first few days following birth. A total of four patients had chylothorax. Two patients who did not respond to medical treatment (somatostatin) were injected with thoracic local batticon and cured. A total of 14 patients were discharged with healing.

Conclusion Cases of progressive prenatal pleural effusions associated with NIHF have a high risk for fetal and neonatal death. We think that extreme prematurity increases postnatal mortality because it negatively affects the development of the lung and heart. A close obstetric follow-up and a multidisciplinary approach are required for the management to be selected.
Implementation Science is Imperative to the Optimization of Obstetric Care
Authors: Hamm Rebecca F. , Iriye Brian K. , Srinivas Sindhu K.
Published: December 2020

In an effort aimed at improving outcomes, obstetric teams have enacted comprehensive care bundles and other clinical tools. Yet, these practices have had limited degrees of success on a national scale. Implementation science aims to bridge the divide between the development of evidence-based interventions and their real-world utilization. This emerging field takes into account key stakeholders at the clinician, institution, and health policy levels. Implementation science evaluates how well an intervention is or can be delivered, to whom, in which context, and how it may be up-scaled and sustained. Other medical disciplines have embraced these concepts with success. The frameworks and theories of implementation science can and should be incorporated into both obstetric research and practice. By doing so, we can increase widespread and timely adoption of evidence and further our common goal of decreasing maternal morbidity and mortality.

Key Points
Pediatric Orbital Roof Fractures: A Ratio of Orbital Dimensions Correlated to Prevalence of Fracture
Authors: Dryden Stephen C. , Meador Andrew G. , Johnston Andrew B. , Eder Adrianna E. , Fleming James C. , Fowler Brian
Published: December 2020

Objective Orbital roof fractures are more likely to occur in younger children, specifically younger than 7 years. Cranium to face ratio decreases with age; however, there is no definition for measurement of the neurocranium or face. We propose using the length of the orbital roof as a measurement of the neurocranium and length of the orbital floor as a tool to estimate midface size. The purpose of this study is to test this measurement as a correlation rate of orbital roof fractures within the pediatric population.

Design This is a retrospective study.

Setting This study was done at the LeBonheur Children's Hospital.

Participants Sixty-six patients with orbital roof fractures were identified and stratified by gender and age, specifically younger than 7 years and 7 years or older.

Main Outcome Measures The main outcome measures were orbital roof length, floor length, and ratio thereof.

Results Mean orbital roof length was 43.4 ± 3.06 and 45.1 ± 3.94 mm for patients <7 and ≥7 years, respectively (p = 0.02). Mean orbital floor length was 41.3 ± 2.99 and 47.7 ± 4.19 for patients <7 and ≥7 years, respectively (p < 0.00001). The mean roof to floor ratio (RTFR) for patients <7 years was 1.051 ± 0.039 and for patients ≥ 7 years was 0.947 ± 0.031 (p < 0.00001).

Conclusion As children age, the relative length of the orbital roof decreases when compared with the orbital floor. The RTFR was more than 1.0 in children younger than 7 years. These differences were statistically significant when compared with children 7 years and older. This measurement shift follows the differences noted in orbital fracture patterns during childhood.
Social stigma and cultural beliefs associated with cleft lip and/or palate: parental perceptions of their experience in Kenya
Authors: Kimotho Stephen Gichuhi , Macharia Fiona Nduta
Published: December 2020

Cleft lip with or without cleft palate (CL/P)—a condition associated with speech, hearing, feeding, and dental problems, as well as anomalies of the bone and soft tissue around the mouth—is a common birth defect around the globe. The prevalence of this condition varies widely across different countries and regions, and is apparently highest among Asians and lowest among Africans. A review of literature reveals that there exists a dearth of information on experiences of parents of children with CL/P and stigma communication, as well as cultural beliefs associated with CL/P in Africa. To fill this gap, we conducted a descriptive qualitative study examining the experiences of parents of children with CL/P, stigma communication, and cultural beliefs associated with CL/P in Kenya. Twenty four in-depth interviews were done involving purposefully sampled parents of children born with CL/P at AIC CURE International Hospital in Nairobi, Kenya. Five overarching themes emerged under the lived experiences of parents of children with CL/P: Emotional experiences; relational experiences; burden of care and concerns; reaction by the public and friends; and source of social support. The stigma messages and beliefs associated with CL/P further exacerbated the stigma. The study revealed that stigma communication associated with CL/P remains a significant source of social and psychological anguish to parents and guardians of children with CL/P. These findings have critical implications for the management of stigma communication associated with CL/P. They point to the need for public awareness campaigns on CL/P to demystify the condition, its causes and treatment. The study shows that raising public awareness of CL/P would go a long way towards addressing the stigma associated with the condition. It underscores the need for open communication and engagement with all stakeholders to manage stigma communication associated with CL/P through culturally appropriate anti-stigma campaigns.
Reduction of background radiation effects for positron lifetime measurements in the slow positron beamline at the Kyoto University Research Reactor
Authors: Nakajima M. , Taguchi R. , Yabuuchi A. , Kinomura A.
Published: December 2020

Positron annihilation lifetime spectroscopy (PALS), which is recognized as one of the major analytical methods of positron annihilation spectroscopy, can directly detect information related to the size of vacancy-type defects from lifetime values. PALS measurements performed under high background radiation have been previously reported. It is well known that coincidence techniques such as age–momentum correlation (AMOC) measurements are effective for the background reduction, but count rates decline significantly. In this study, a preliminary experiment was performed to reduce the influence of the background radiation without the coincidence technique in the pulsing system of the Kyoto University research Reactor (KUR) slow positron beamline. This experiment involved the introduction of a gate circuit for the background radiation discrimination using a dynode signal from a single scintillation detector (photomultiplier). After introducing the gate circuit, the time resolution and the lifetime value of Kapton were 308 ps and 388 ± 3 ps, respectively, with count rates of ∼400 counts/s at a KUR 5 MW operation. In the AMOC measurement, the time resolution and the lifetime value of Kapton were 297 ps and 380 ± 7 ps, respectively, with count rates of ∼40 counts/s at a KUR 5 MW operation. When the single detector with the gate circuit was used, the count rate was ∼1 order of magnitude higher than those of the AMOC measurements, while the time resolutions of the two methods were comparable.
Effect of electrodes on microsecond explosion of thin metal wires in vacuum
Authors: Sarkisov G. S.
Published: December 2020

An order of magnitude difference was observed in the energy deposition during a microsecond explosion of thin nickel wires in a vacuum, depending on the design of the wire-holding electrodes. In one case, cylindrical polished stainless steel (ss) electrodes with a rounded edge have a small axial hole of 0.3 mm to hold a thin wire. In the second case, these were the same polished electrodes without an axial hole, and the wire was attached to the side of the electrode with a kapton tape. For the electrodes with an axial hole, a voltage breakdown appears when the wire reaches a low temperature of ∼570 K due to the generation of the parasitic plasma discharges from the wire-holder contact. In a long timescale of ∼30 μs, wire resistive heating was interrupted by plasma generations 6 times up to the moment of melting. For the same electrodes without holes, the wire reaches a temperature of ∼1870 K during an ∼2 μs single-stage heating, and the shunting plasma was generated due to the evaporation of impurities from the hot metal surface and avalanche ionization by thermo-emitted electrons from the hot metal surface. We observe similar effects for Cu, Ti, and Pt wires. This effect is important for slow microsecond exploding wires in a vacuum and negligible for fast nanosecond explosions.
A new multi-beam apparatus for the study of surface chemistry routes to formation of complex organic molecules in space
Authors: Congiu E. , Sow A. , Nguyen T. , Baouche S. , Dulieu F.
Published: December 2020

A multi-beam ultra-high vacuum apparatus is presented. In this article, we describe the design and construction of a new laboratory astrophysics experiment—VErs de NoUvelles Synthèses (VENUS)—that recreates the solid-state non-energetic formation conditions of complex organic molecules in dark clouds and circumstellar environments. The novel implementation of four operational differentially pumped beam lines will be used to determine the feasibility and the rates for the various reactions that contribute to formation of molecules containing more than six atoms. Data are collected by means of Fourier transform infrared spectroscopy and quadrupole mass spectrometry. The gold-coated sample holder reaches temperatures between 7 K and 400 K. The apparatus was carefully calibrated and the acquisition system was developed to ensure that experimental parameters are recorded as accurately as possible. A great effort has been made to have the beam lines converge toward the sample. Experiments have been developed to check the beam alignment using reacting systems of neutral species (NH3 and H2CO). Preliminary original results were obtained for the {NO + H} system, which shows that chemistry occurs only in the very first outer layer of the deposited species, that is, the chemical layer and the physical layer coincide. This article illustrates the characteristics, performance, and future potential of the new apparatus in view of the forthcoming launch of the James Webb Space Telescope. We show that VENUS will have a major impact through its contributions to surface science and astrochemistry.
Scanning thermal microscopy on samples of varying effective thermal conductivities and identical flat surfaces
Authors: Guen E. , Chapuis P.-O. , Rajkumar R. , Dobson P. S. , Mills G. , Weaver J. M. R. , Gomés S.
Published: December 2020

We propose an approach for the characterization of scanning thermal microscopy (SThM) probe response using a sample with silicon dioxide steps. The chessboard-like sample provides a series of nine surfaces made of the same material, with identical roughness, but consisting of different thicknesses of silica layers standing on a single silicon wafer. The nine regions have different effective thermal conductivities, allowing the calibration of SThM probes within a given set of surface conditions. A key benefit is the possibility of comparing the spatial resolution and the sensitivity to vertical inhomogeneities of the sample for different probes. A model is provided to determine the thermal contact area and contact thermal resistance from the experimental data. The results underline that ballistic heat conduction can be significant in crystalline substrates below the top thin films, especially for film thicknesses lower than 200 nm and effective thermal contact radius lower than 200 nm. They also highlight the sensitivity of SThM to ultrathin films, as well as the substrate below micrometric films under in-air conditions but not when in vacuum. This work advances quantitative nanometer-scale thermal metrology, where usual photothermal methods are more difficult to implement.
Thermophysical Properties of 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][(CF3SO2)2N]—New Data, Reference Data, and Reference Correlations
Authors: Paredes X. , Queirós C. S. G. P. , Santos F. J. V. , Santos A. F. , Santos M. S. C. S. , Lourenço M. J. V. , Nieto de Castro C. A.
Published: December 2020

Published data on the thermophysical properties of ionic liquids are normally in disagreement if results from different laboratories, using different samples and different measurement protocols, are compared. This fact was recognized years ago at the level of the International Union of Pure and Applied Chemistry (IUPAC), which established IUPAC Project 2002-005-1-100 (Thermodynamics of ionic liquids, ionic liquid mixtures, and the development of standardized systems), with the main objective of recommending a reference ionic liquid, making reference-quality measurements on selected thermophysical properties of both the pure ionic liquid and its mixtures, establishing recommended values for the properties measured, and providing recommendations on measurement methods. The ionic liquid chosen was 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][(CF3SO2)2N], because of its stability, low viscosity compared with that of most common ionic liquids, low water solubility, ease of preparation and purification, and commercial availability. Due to its hydrophobicity, it is capable of being obtained very pure, with water amounts as small as 20 ppm. This paper reports new results obtained with the sample of [C6mim][(CF3SO2)2N] synthesized in the IUPAC project, namely on density, speed of sound, surface tension, and refractive index, as well as thermal conductivity of a commercial sample at P = 0.1 MPa, as a function of temperature, and proposes reference data and reference data correlations for the density, speed of sound, heat capacity, surface tension, viscosity, electrical conductivity, thermal conductivity, refractive index, ion self-diffusion coefficient, and melting temperature of this ionic liquid at 0.1 MPa, as a function of temperature, using these and other data reported up to July 2020. Rheological measurements demonstrated that this ionic liquid is Newtonian.
Vectorial calibration of superconducting magnets with a quantum magnetic sensor
Authors: Botsch L. , Raatz N. , Pezzagna S. , Staacke R. , John R. , Abel B. , Esquinazi P. D. , Meijer J. , Diziain S.
Published: December 2020

Cryogenic vector magnet systems make it possible to study the anisotropic magnetic properties of materials without mechanically rotating the sample but by electrically tilting and turning the magnetic field. Vector magnetic fields generated inside superconducting vector magnets are generally measured with three Hall sensors. These three probes must be calibrated over a range of temperatures, and the temperature-dependent calibrations cannot be easily carried out inside an already magnetized superconducting magnet because of remaining magnetic fields. A single magnetometer based on an ensemble of nitrogen vacancy (NV) centers in diamond is proposed to overcome these limitations. The quenching of the photoluminescence intensity emitted by NV centers can determine the field in the remanent state of the solenoids and allows an easy and fast canceling of the residual magnetic field. Once the field is reset to zero, the calibration of this magnetometer can be performed in situ by a single measurement of an optically detected magnetic resonance spectrum. Thereby, these magnetometers do not require any additional temperature-dependent calibrations outside the magnet and offer the possibility to measure vector magnetic fields in three dimensions with a single sensor. Its axial alignment is given by the crystal structure of the diamond host, which increases the accuracy of the field orientation measured with this sensor, compared to the classical arrangement of three Hall sensors. It is foreseeable that the magnetometer described here has the potential to be applied in various fields in the future, such as the characterization of ferromagnetic core solenoids or other magnetic arrangements.
Recommended Values for the Viscosity in the Limit of Zero Density and its Initial Density Dependence for Twelve Gases and Vapors: Revisited from Experiment between 297 K and 691 K
Authors: Vogel Eckhard
Published: December 2020

Previously published experimental viscosity data at low density, originally obtained using all-quartz oscillating-disk viscometers for 12 gases and vapors in the temperature range between 297 K and 691 K, were re-evaluated after an improved re-calibration. The relative combined expanded (k = 2) uncertainty of the re-evaluated data is 0.2% near room temperature and increases to 0.3% at higher temperatures. The re-evaluated data for sulfur hexafluoride, methanol, n-pentane, n-hexane, n-heptane, neopentane, cyclohexane, benzene, toluene, p-xylene, phenol, and triethylamine were arranged in approximately isothermal groups and converted into quasi-isothermal viscosity data using a first-order Taylor series in temperature. Then, they were evaluated by means of a series expansion truncated at first order to obtain the zero-density and initial density viscosity coefficients, η(0) and η(1). When the number of isothermal data or their quality was not adequate, the Rainwater–Friend theory for the initial density dependence of the viscosity was additionally used to derive η(0) and η(1) values. Finally, reliable η(0) and η(1) values, preferably obtained from the isotherms, were recommended as reference values for the 12 gases and vapors in the measured temperature range to be applied when generating any new viscosity formulation.
A note on the history of photoacoustic, thermal lensing, and photothermal deflection techniques
Authors: Bertolotti Mario , Li Voti Roberto
Published: December 2020

We review the history of photoacoustic, thermal lensing, and photothermal deflection techniques from early experiments to the current time. The paper also describes the main fields of application in chronological order, showing the primary advantages and listing initial technological developments.
Nonlinear focal mapping of ferroelectric domain walls in LiNbO3: Analysis of the SHG microscopy contrast mechanism
Authors: Spychala K. J. , Mackwitz P. , Rüsing M. , Widhalm A. , Berth G. , Silberhorn C. , Zrenner A.
Published: December 2020

Second-harmonic (SH) microscopy is a widely used tool for the study of ferroelectric domains, domain walls, and their substructure. Yet, the contrast mechanism, particularly for the commonly used large numerical aperture, is not fully understood. In this work, we examine the contrast mechanism of SH microscopy in periodically poled LiNbO3 for the case of tightly focused laser beams and in the surface-near regime. The results are interpreted along theoretical calculations that include a vectorial field model for excitation and detection. Our model suggests that the characteristic contrasts mainly originate from interference patterns in the signal due to the sign change of the nonlinear susceptibility at the domain boundary. We find that for large numerical apertures, the tight focusing induces polarization components (axial and orthogonal to incident polarization), and the subsequent mixing of differently polarized light fields via off diagonal tensor elements plays an important role for the domain wall contrast. With our model-based analysis, this work represents the foundation for the investigation of the substructure of domain walls with second-harmonic microscopy.
Inhomogeneous surface tension of chemically active fluid interfaces
Authors: Squarcini Alessio , Malgaretti Paolo
Published: December 2020

We study the dependence of the surface tension of a fluid interface on the density profile of a third suspended phase. By means of an approximated model for the binary mixture and of a perturbative approach, we derive closed-form expressions for the free energy of the system and for the surface tension of the interface. Our results show a remarkable non-monotonous dependence of the surface tension on the spatial separation between the peaks of the density of the suspended phase. Our results also predict the local value of the surface tension in the case in which the density of the suspended phase is not homogeneous along the interface.
Effect of channel geometry on a density wave induced by gravity and chemoconvection in miscible reacting fluids
Authors: Bratsun D. A. , Mizev A. I. , Mosheva E. A. , Siraev R. R.
Published: December 2020

We study a two-layer system of initially separated aqueous solutions of an acid and a base placed in a vertically oriented Hele–Shaw cell. After the reactants, a second-order neutralization reaction begins, which is accompanied by the release of salt. Recently, we found that, contrary to expectations of the occurrence of fingering convection, a density wave pattern may occur in this system at some values of initial concentrations of acid and base. This wave has a perfectly planar front with a nearly discontinuous change in density across the front and propagates fast compared with the characteristic diffusion times. The shock wavefront separates the domains of a motionless fluid and intense convective mixing. In this work, we study, both theoretically and experimentally, the influence of the cavity geometry on the dynamics of the density wave. Specifically, we consider the following cases: when (a) the aspect ratio of the cavity changes, (b) the gap width of the Hele–Shaw cell is locally varied, and (c) the oblique obstacle is placed inside the cell. The set of governing equations includes the equation of motion based on Darcy’s law as well as the transfer equations for species. The experimental observations presented for the wave bending around the obstacle are in good agreement with the numerical simulation.
Mechanism of C60 rotation and translation on hexagonal boron-nitride monolayer
Authors: Vaezi Mehran , Nejat Pishkenari Hossein , Nemati Alireza
Published: December 2020

Newly synthesized nanocars have shown great potential to transport molecular payloads. Since wheels of nanocars dominate their motion, the study of the wheels helps us to design a suitable surface for them. We investigated C60 thermal diffusion on the hexagonal boron-nitride (h-BN) monolayer as the wheel of nanocars. We calculated C60 potential energy variation during the translational and rotational motions at different points on the substrate. The study of the energy barriers and diffusion coefficients of the molecule at different temperatures indicated three noticeable changes in the C60 motion regime. C60 starts to slide on the surface at 30 K–40 K, slides freely on the boron-nitride monolayer at 100 K–150 K, and shows rolling motions at temperatures higher than 500 K. The anomaly parameter of the motion reveals that C60 has a diffusive motion on the boron-nitride substrate at low temperatures and experiences superdiffusion with Levy flight motions at higher temperatures. A comparison of the fullerene motion on the boron-nitride and graphene surfaces demonstrated that the analogous structure of the graphene and hexagonal boron-nitride led to similar characteristics such as anomaly parameters and the temperatures at which the motion regime changes. The results of this study empower us to predict that fullerene prefers to move on boron-nitride sections on a hybrid substrate composed of graphene and boron-nitride. This property can be utilized to design pathways or regions on a surface to steer or trap the C60 or other molecular machines, which is a step toward directional transportation at the molecular scale.
Resistive switching kinetics and second-order effects in parylene-based memristors
Authors: Matsukatova Anna N. , Emelyanov Andrey V. , Minnekhanov Anton A. , Nesmelov Aleksandr A. , Vdovichenko Artem Yu. , Chvalun Sergey N. , Rylkov Vladimir V. , Forsh Pavel A. , Demin Viacheslav A. , Kashkarov Pavel K. , Kovalchuk Mikhail V.
Published: December 2020

Parylene is a widely used polymer possessing advantages such as simple and cheap production, possibility of fabrication on flexible substrates, transparency, and safety for the human body. Moreover, parylene can be used as an active layer of memristors—circuit design elements that are promising for the implementation of hardware neuromorphic systems. Recent studies show that memristors are not merely memory but also highly dynamical systems that can encode timing information. Here, a study of the switching kinetics and the timing second-order effects in memristors based on pristine and nanocomposite (with embedded silver nanoparticles) parylene is presented. The strong decrease in the resistive switching time and increase in the amplitude of the resistive state change after preliminary heating pulses are revealed. These effects are explained by the local heating of the parylene matrix by electric pulses, and the given explanation is supported by the numerical electrothermal model. Spike-timing-dependent plasticity with symmetrical nonoverlapping spikes is demonstrated. The obtained results indicate a possibility of the utilization of second-order effects in the development of the neuromorphic systems.
Microscopic mechanisms for phase coexistence and electric polarization enhancement in Mn1−xIrxWO4 + δ
Authors: Yu H. W. , Wang X. L. , Zhang Q. L. , Liu M. F. , Li L. , Xu Z. C. , Yan Z. B. , Liu S. G.
Published: December 2020

We investigate the magnetic and ferroelectric behaviors of 5d Ir4+ substituted Mn1−xIrxWO4 + δ samples. The electric polarization is enhanced to a certain extent due to the Ir substitution of Mn. Furthermore, the non-polar AF1 phase is partially suppressed by the ferroelectric AF2 phase, resulting in the coexistence of the two phases below TAF1. It is suggested that the lattice distortion, the suppressed magnetic moment, and the increased Dzyaloshinskii–Moriya interaction are the key reasons for the enhanced polarization and the stabilized ferroelectric AF2 phase.
Thermal transport properties of Ni–Co-based superalloy
Authors: Miura Asuka , Osada Toshio , Kawagishi Kyoko , Uchida Ken-ichi
Published: December 2020

We report systematic measurements of thermal transport properties of a Ni–Co-based superalloy at temperatures ranging from room temperature to around 800 K. In this temperature range, the thermal diffusivity and conductivity of the superalloy monotonically increase with an increase in the temperature, while the specific heat capacity is almost temperature-independent. We found that the observed thermal conductivity of the Ni–Co-based superalloy is higher than the electronic thermal conductivity expected from the Wiedemann–Franz law, indicating the substantial contribution of phonon thermal conductivity. The temperature dependence of the phonon thermal conductivity for the Ni–Co-based superalloy was observed to be weaker than that for other Ni-based alloys, which can be qualitatively explained by enhanced phonon scattering due to small γ′-phase precipitates in the superalloy. This result suggests possible tuning of the thermal conductivity of the superalloy based on phonon transport engineering.
High-precision nonlocal temporal correlation identification of entangled photon pairs for quantum clock synchronization
Authors: Quan Runai , Dong Ruifang , Xiang Xiao , Li Baihong , Liu Tao , Zhang Shougang
Published: December 2020

High-precision nonlocal temporal correlation identification in entangled photon pairs is critical to measure the time offset between remote independent time scales for many quantum information applications. The first nonlocal correlation identification was reported in 2009, which extracts the time offset via the algorithm of iterative fast Fourier transformations and their inverse. The best identification resolution is restricted by the peak identification threshold of the algorithm, and thus the time offset calculation precision is limited. In this paper, an improvement for the identification is presented both in resolution and precision via a modified algorithm of direct cross correlation extraction. A flexible resolution down to 1 ps is realized, which is only dependent on the least significant bit resolution of the time-tagging device. The attainable precision is shown to be mainly determined by the inherent timing jitter of single photon detectors, the acquired pair rate, and acquisition time, and a sub-picosecond precision (0.72 ps) has been achieved at an acquisition time of 4.5 s. This high-precision nonlocal measurement realization provides a solid foundation for the field applications of entanglement-based quantum clock synchronization, ranging, and communications.