bluuebunny/crossref_metadata_2025 huggingface dataset:
LncRNA: a new perspective on the study of neurological diseases
Authors: Ma Yun , He Siqi , Gu Tianhe , Liu Yixuan , He Shuya , Jiang Zhisheng
Published: April 2022

Long non-coding RNAs (lncRNAs) are a class of non-coding RNA with a length greater than 200 nt. It has a mRNA-like structure, formed by splicing after transcription, and contains a polyA tail and a promoter, of whom promoter plays a role by binding transcription factors. LncRNAs’ sequences are low in conservation, and other species can only find a handful of the same lncRNAs as humans, and there are different splicing ways during the differentiation of identical species, with spatiotemporal expression specificity. With developing high-throughput sequencing and bioinformatics, found that more and more lncRNAs associated with nervous system disease. This article deals with the regulation of certain lncRNAs in the nervous system disease, by mean of to understand its mechanism of action, and the pathogenesis of some neurological diseases have a fresh understanding, deposit a foundation for resulting research and clinical treatment of disease.
First detection of AlF line emission towards M-type AGB stars
Authors: Saberi M. , Khouri T. , Velilla-Prieto L. , Fonfría J. P. , Vlemmings W. H. T. , Wedemeyer S.
Published: April 2022

The nucleosynthesis production of fluorine (F) is still a matter of debate. Asymptotic giant branch (AGB) stars are one of the main candidates for F production. However, their contribution to the total F budget is not fully known due to the lack of observations. In this paper, we report the detection of aluminium monofluoride (AlF) line emission, one of the two main carriers of F in the gas-phase in the outflow of evolved stars, towards five nearby oxygen-rich (M-type) AGB stars. We studied the Atacama large millimetre/sub-millimetre array (ALMA) observations of AlF (v = 0, J = 4—3, 9–8, 10–9, and 15–14) and (v = 1, J = 7–6) line emission towards o Ceti, and (v = 0, J = 7–6 and 15–14) lines towards R Leo. We also report a tentative detection of AlF (v = 0, J = 7–6) line in IK Tau, (v = 0, J = 15–14) line towards R Dor, and (v = 0, J = 7–6 and J = 15–14) lines in W Hya. From spatially resolved observations, we estimated the AlF emitting region with a radius ~11R⋆ for o Ceti and ~9R⋆ for R Leo. From population diagram analysis, we report the AlF column densities of ~5.8 × 1015 cm−2 and ~3 × 1015 cm−2 for o Ceti and R Leo, respectively, within these regions. For o Ceti, we used the C18O (v = 0, J = 3–2) observations to estimate the H2 column density of the emitting region. We found a fractional abundance of fAIF/H2 ~ (2.5 ± 1.7) × 10−8. This gives a lower limit on the F budget in o Ceti and is compatible with the solar F budget fF/H2 = (5 ± 2) × 10−8. For R Leo, a fractional abundance fAIF/H2 = (1.2 ± 0.5) × 10−8 is estimated. For other sources, we cannot precisely determine the emitting region based on the available data. Assuming an emitting region with a radius of ~11R⋆ and the rotational temperatures derived for o Ceti and R Leo, we crudely approximated the AlF column density to be ~(1.2−1.5) × 1015 cm−2 in W Hya, ~(2.5−3.0) × 1014 cm−2 in R Dor, and ~(0.6−1.0) × 1016 cm−2 in IK Tau. These result in fractional abundances within a range of fAIF/H2 ~ (0.1 − 4) × 10−8 in W Hya, R Dor, and IK Tau.
Deep learning-based imaging in radio interferometry
Authors: Schmidt K. , Geyer F. , Fröse S. , Blomenkamp P.-S. , Brüggen M. , de Gasperin F. , Elsässer D. , Rhode W.
Published: April 2022

Context.The sparse layouts of radio interferometers result in an incomplete sampling of the sky in Fourier space which leads to artifacts in the reconstructed images. Cleaning these systematic effects is essential for the scientific use of radiointerferometric images.

Aims.Established reconstruction methods are often time-consuming, require expert knowledge, and suffer from a lack of reproducibility. We have developed a prototype deep learning-based method that generates reproducible images in an expedient fashion.

Methods.To this end, we take advantage of the efficiency of convolutional neural networks to reconstruct image data from incomplete information in Fourier space. The neural network architecture is inspired by super-resolution models that utilize residual blocks. Using simulated data of radio galaxies that are composed of Gaussian components, we trained deep learning models whose reconstruction capability is quantified using various measures.

Results.The reconstruction performance is evaluated on clean and noisy input data by comparing the resulting predictions with the true source images. We find that source angles and sizes are well reproduced, while the recovered fluxes show substantial scatter, albeit not worse than existing methods without fine-tuning. Finally, we propose more advanced approaches using deep learning that include uncertainty estimates and a concept to analyze larger images.
Editorial
Authors: Haas Johannes-Peter
Published: April 2022

Liebe Leser*innen der Aktuellen Rheumatologie,

die Aufgabe, ein Themenheft zur Kinderrheumatologie zu gestalten, haben die
Autor*innen und ich selbst als Gasteditor sehr gerne angenommen. Wir haben
uns dabei ganz bewusst neben hochaktuellen Themen für Bereiche der
Kinderrheumatologie entschieden, die manchmal etwas zu wenig Beachtung finden.
Das Pädiatrische Inflammatorische Multisystem Syndrom (PIMS)
in der COVID-19 Pandemie
Authors: Brück Normi , Schütz Catharina , Kallinich Tilmann
Published: April 2022

Nach einer meist mild verlaufenden SARS-CoV-2-Infektion kommt es bei einem
kleinen Teil der Kinder nach einem Zeitraum von ca. 6–8 Wochen zu einer
ausgeprägten multisystemischen Hyperinflammation (Pediatriac
multisystemic inflammatory syndrome (PIMS)). Klinisch präsentieren sich
diese Patienten mit Zeichen eines Kawasaki-Syndroms bzw. eines toxischen
Schocksyndroms. Gerade die kardiale Manifestation mit einer deutlichen
Einschränkung der Herzfunktion erfordert in vielen Fällen eine
intensivmedizinische Behandlung.

Die Pathophysiologie ist trotz des beeindruckenden Erkenntnisgewinns der letzten
1 ½ Jahre noch unklar. Möglicherweise spielen
Superantigene eine wesentliche Rolle, die T-Zellen an einer bestimmten
β-Kette des T-Zellrezeptors polyklonal stimulieren.

Neben den z.T. intensivmedizinischen supportiven Maßnahmen werden zur
Kontrolle der Inflammation intravenöse Immunglobuline, Steroide und
Biologika eingesetzt.
Physiotherapie und Sport bei Kinderrheuma – Shake your
bones
Authors: Gizik Josephine , Meister Sophia , Hartmann Matthias , Sahm Daniel , Georgi Mathias , Baumeister Nadja , Kühne Mareike , Haas Johannes-Peter , Schwirtz Ansgar
Published: April 2022

Im Rahmen kindlicher rheumatischer Erkrankungen haben die zumeist schmerzhaften
Entzündungsvorgänge am muskulo-skelettalen System
(z. B.: Gelenke, Muskeln, Sehnen, Gefäße) Auswirkungen
auf die tägliche Mobilität der Betroffenen. Immobilität,
körperliche und sportliche Inaktivität sind oft die Folge. Die
geltenden Richtlinien der Nationalen Empfehlungen für Bewegung und
Bewegungsförderung werden daher oftmals nicht erreicht.
Bewegungsreduzierte oder -inaktive Patienten können jedoch durch
verschiedene Maßnahmen in ihrem Bewegungsverhalten gefördert
werden. Die Physiotherapie bietet eine erste Möglichkeit in
geschütztem Rahmen und unter fachlicher Aufsicht körperlich und
sportlich aktiv zu sein. Neben der Wiederherstellung und Verbesserung des
physiologischen Bewegungsausmaßes liegen die Erhaltung der
Selbstständigkeit und Lebensqualität im Vordergrund der
physiotherapeutischen Behandlung. Dazu zählen Aktivierung, Anbahnung von
physiologischen Bewegungsabläufen, Korrektur von Gelenkachsen und das
Vermitteln von Körperwahrnehmung bei körperlicher
Aktivität. Medizinisches Fachwissen und Verständnis sowie Wissen
über die Anforderungen verschiedener Sportartenprofile
ermöglicht gezielte Hilfestellungen. Durch kontinuierliche, engmaschige
Begleitung und langsame Steigerung von Intensität und Umfang in der
Physiotherapie können Ängste und Bedenken bezüglich dem
Wiedereinstieg bzw. Einstieg in sportliche Betätigung abgebaut werden.
Der jeweilige Gesundheitszustand und die Situation der
Entzündungsaktivität sind maßgebend für die
Therapieinterventionen. Sport gilt heute in der Physiotherapie als
Therapieelement und hilft Beschwerden zu lindern, verbessert körperliche
Defizite und vermittelt dabei Freude an der Bewegung. Für
Alltagsaktivitäten und den Freizeitsport kann eine individuelle
Sportberatung basierend auf dem bestehenden Erkrankungsstatus, dem funktionellen
und sportmotorischen Leistungsniveau sowie den eigenen Interessen wirkungsvoll
zu einem aktiven Lebensstil beitragen. Eine weitere Möglichkeit der
angeleiteten Bewegungsförderung stellt der Schulsport dar. Individuelle,
differenzierte Schulsportteilnahmebescheinigungen verbessern die Inklusion. Ein
auf den Erkrankungsstatus angepasstes und vorgegebenes Trainingsprogramm kann
mithilfe konkreter Vorgaben bei der Umsetzung der sportlichen Ziele
unterstützen. In Zukunft soll ein digital gestütztes
professionelles Monitoring die Bewegungsempfehlungen für zuhause noch
weiter verbessern und helfen den Mangel an flächendeckenden
Beratungsstellen für Erkrankte mit kindlichem Rheuma zu verringern.
Cisplatin – A more Efficient Drug in Combination with Radionuclides?
Authors: Reissig Falco , Runge Roswitha , Naumann Anne , Kotzerke Jörg
Published: April 2022

Aim The combination of conventional chemotherapeutic drugs with radionuclides or external radiation is discussed for a long period of time. The major advantage of a successful combination therapy is the reduction of severe side effects by decreasing the needed dose and simultaneously increasing therapeutic efficiency.

Methods In this study, pUC19 plasmid DNA was incubated with the cytostatic drug cisplatin and additionally irradiated with 99mTc, 188Re and 223Ra. To verify the contribution of possibly excited platinum atoms to the emission of Auger electrons we determined DNA damages, such as single- and double strand breaks.

Results The threshold concentration value of cisplatin, which was tolerated by pUC19 plasmid DNA was determined to be 18–24 nM. Nevertheless, even at higher dose values (>100 Gy) and simultaneous incubation of cisplatin to 200 ng plasmid DNA, no significant increase in the number of induced single- and double-strand breaks was obtained, compared to the damage solely caused by the radionuclides.

Conclusion We thereby conclude that there is no direct dependence of the mechanism of strand break induction to the absence or presence of platinum atoms attached to the DNA. Reported increasing DNA damages in therapy approaches on a cellular level strongly depend on the study design and are mainly influenced by repair mechanisms in living cells. Nevertheless, the use of radioactive cisplatin, containing the Auger electron emitter 191Pt, 193mPt or 195mPt, is a bright prospect for future therapy by killing tumor cells combining two operating principles: a cytostatic drug and a radiopharmaceutical at the same time.
Inkorporationsüberwachung des Personals einer nuklearmedizinischen Therapiestation mit Einsatz von I-131 und Lu-177
Authors: Wanke Carsten , Szemerski Bastian , Geworski Lilli
Published: April 2022

Ziele Neben der etablierten Radiojodtherapie werden in Deutschland zunehmend auch Therapien mit Lutetium-177 stationär durchgeführt. All diese Therapien sind bei der Abschätzung der potenziellen Inkorporationsdosis und der Inkorporationsüberwachung des Personals zu berücksichtigen. Dieser Beitrag zeigt die Erfahrungen und Ergebnisse der Inkorporationsüberwachung auf einer nuklearmedizinischen Therapiestation eines Universitätsklinikums.

Methoden Personal einer nuklearmedizinischen Therapiestation wurde regelmäßig mittels eines Ganzkörperzählers auf Inkorporation überwacht. Über einen Zeitraum von 12 Monaten erfolgten insgesamt 234 Messungen. Unter Berücksichtigung der im jeweiligen Zeitraum gehandhabten oder applizierten Aktivitäten wurden Inkorporationsfaktoren ermittelt.

Ergebnisse In ca. 74 % der Messungen wurde keine Inkorporation festgestellt. In den übrigen Messungen wurde Aktivität erkannt. Bei Annahme von Inkorporation würden sich hieraus maximale Expositionen von weniger als 0,15 mSv effektiver Dosis pro Messung ergeben. Die in dieser Arbeit ermittelten Inkorporationsfaktoren lagen für alle Personengruppen bis auf das Personal der radiochemischen Qualitätskontrolle in einer Größenordnung von 10–7. Für die letztgenannte Personengruppe kann nur eine Obergrenze des Inkorporationsfaktors von 10–5 angegeben werden.

Schlussfolgerung Das Inkorporationsrisiko für Personal einer nuklearmedizinischen Therapiestation kann als gering angesehen werden. Ein Inkorporationsfaktor von 10–7 ist für ärztliches Personal, Pflegepersonal, Reinigungspersonal und das Personal, das radiochemische Synthesen durchführt, angemessen.
Successful Rituximab Therapy for Pediatric Antiphospholipid-Related Chorea: A Case Report and Review of the Literature
Authors: D'hont Alexia , De Wachter Matthias , Driesen Yentl , Sabato Vito , Joos Rik , Ceulemans Berten
Published: April 2022

Chorea is considered a nonthrombotic manifestation of the antiphospholipid syndrome, often preceding thrombotic events in children. It can be present in up to 5% of pediatric patients with antiphospholipid syndrome. Immunomodulatory treatment regimens seem to be successful in these patients, emphasizing the underlying immunological etiology. Corticosteroids are considered first-line treatment, but chorea tends to be therapy-resistant and guidelines about second-line therapy in children are solely based on small case studies. We present a case of a therapy-resistant chorea, successfully treated with rituximab. Furthermore, we give an overview of the existing literature concerning rituximab for the treatment of chorea in children. Our findings indicate that rituximab can be considered a safe option to treat antiphospholipid syndrome-related chorea in children.
Stereocontrolled Synthesis of (±)-Grandisol
Authors: Bartlett William R. , Read de Alaniz Javier , Carlson Janet L. , Dillon Maria P. , Edstrom Eric , Fischer Derek A. , Goldblum Adam A , Luedtke Gregory R. , Paneitz Gregory W. , Ryter Kendal , Schulz Mark , Shepard Donnie A. , Switzer Christopher
Published: April 2022

A synthetic approach to grandisol is described. The route to the cyclobutane core relies on an efficient intramolecular [2+2] cyclo­addition that establishes the required cis-ring fusion at the adjacent side chains of the cyclobutane ring. Using a new two-step lithium/halide homologation procedure, norgrandisol was efficiently converted into grandisol. This new approach enables the synthesis of grandisol in five steps from commercially available starting material in 22% overall yield.
Rapid and Facile Synthesis of Isomaleimides: Dehydration of Maleamic Acids using Methanesulfonyl Chloride
Authors: Croatt Mitchell P. , Alam Khyarul , McFee Elvis C.
Published: April 2022

The dehydration of maleamic acids using methanesulfonyl chloride as a dehydrating agent to selectively and rapidly (<15 min) generate isomaleimides is reported. A variety of maleamic acid derivatives produce the corresponding isomaleimides in good to excellent yields. Adaptation of this protocol under flow synthesis allows for similar efficiency and decreased reaction times (13 seconds residence time). It was also possible to convert maleic anhydride into the desired isomaleimide in a two-step, one-flask operation.
Preparation of Ring-Methoxylated Arylnitromethanes by the Victor Meyer Reaction
Authors: Kislyi Victor P. , Maksimenko Anna S. , Buikin Petr A. , Daeva Elena D. , Semenov Victor V.
Published: April 2022

Easily accessible and stable ring-methoxylated benzyl chlorides react with AgNO2 to give mixtures of the corresponding arylnitromethanes and nitrite esters. A modified approach for the isolation of arylnitromethanes is described, which represents a valuable improvement of the established Victor Meyer reaction. The isolation technique, which involves reaction of the nitrite ester with urea in methanol, allows the desired arylnitromethanes to be isolated, without loss, in 29–75% yields, and generates the corresponding recyclable benzyl alcohols. Unexpectedly, ring-methoxylated benzyl iodides cannot be used because they are not sufficiently stable and produce tars under the developed reaction conditions.
Toward a Learning Health Care System: A Systematic Review and Evidence-Based Conceptual Framework for Implementation of Clinical Analytics in a Digital Hospital
Authors: Lim Han Chang , Austin Jodie A. , van der Vegt Anton H. , Rahimi Amir Kamel , Canfell Oliver J. , Mifsud Jayden , Pole Jason D. , Barras Michael A. , Hodgson Tobias , Shrapnel Sally , Sullivan Clair M.
Published: April 2022

Objective A learning health care system (LHS) uses routinely collected data to continuously monitor and improve health care outcomes. Little is reported on the challenges and methods used to implement the analytics underpinning an LHS. Our aim was to systematically review the literature for reports of real-time clinical analytics implementation in digital hospitals and to use these findings to synthesize a conceptual framework for LHS implementation.

Methods Embase, PubMed, and Web of Science databases were searched for clinical analytics derived from electronic health records in adult inpatient and emergency department settings between 2015 and 2021. Evidence was coded from the final study selection that related to (1) dashboard implementation challenges, (2) methods to overcome implementation challenges, and (3) dashboard assessment and impact. The evidences obtained, together with evidence extracted from relevant prior reviews, were mapped to an existing digital health transformation model to derive a conceptual framework for LHS analytics implementation.

Results A total of 238 candidate articles were reviewed and 14 met inclusion criteria. From the selected studies, we extracted 37 implementation challenges and 64 methods employed to overcome such challenges. We identified common approaches for evaluating the implementation of clinical dashboards. Six studies assessed clinical process outcomes and only four studies evaluated patient health outcomes. A conceptual framework for implementing the analytics of an LHS was developed.

Conclusion Health care organizations face diverse challenges when trying to implement real-time data analytics. These challenges have shifted over the past decade. While prior reviews identified fundamental information problems, such as data size and complexity, our review uncovered more postpilot challenges, such as supporting diverse users, workflows, and user-interface screens. Our review identified practical methods to overcome these challenges which have been incorporated into a conceptual framework. It is hoped this framework will support health care organizations deploying near-real-time clinical dashboards and progress toward an LHS.
Single-Stage Posterior Transpedicular Corpectomy and 360-Degree Reconstruction for Thoracic and Lumbar Burst Fractures: Technical Nuances and Outcomes
Authors: Anania Carla Daniela , Bono Beatrice Claudia , Tropeano Mariapia , Fornari Maurizio , Servadei Franco , Costa Francesco
Published: April 2022

Background We evaluate the feasibility of a single-stage posterior corpectomy and circumferential arthrodesis with the aid of spinal navigation for the treatment of traumatic thoracolumbar burst fractures.

Methods This was a single-center, retrospective study. Demographics, clinical, and radiologic data of 19 patients who underwent surgery at our institution for thoracolumbar burst fractures between 2016 and 2019 were collected. All patients enrolled in the present study underwent surgery by means of posterior fixation and transpedicular corpectomy with the aid of an intraoperative image-guided neuronavigation system.

Results Postoperative correction of the vertebral height ratio was achieved in all cases, with an average increase of 23.6% (p = 0.0005). No statistical differences (p = 0.9) were found comparing 1- and 3-month postoperative CT scans, in relation to vertebral height ratio. A statistically significant difference was found between the pre- and postoperative kyphotic angles for the thoracolumbar and lumbar segments (p = 0.0018 and 0.005, respectively), but no difference was found between kyphotic angles at the 3-month follow-up. A unilateral approach was performed on 15 patients (79%), while 4 cases (21%) required a bilateral laminectomy. We did not observe any significant intraoperative complication.

Conclusion Single-stage posterior corpectomy and fixation is a safe and effective approach for thoracic and lumbar burst fractures. It provides excellent 360-degree reconstruction in a single surgical stage with satisfactory results in terms of kyphosis reduction, biomechanical stability, and reduced invasiveness. Spinal navigation represents a fundamental tool to overcome some anatomical limits of the presented technique.
A Re-evaluation of Tinnitus Reliability Testing
Authors: Jacobson Gary P. , Henderson Jennifer A. , McCaslin Devin L.
Published: April 2022

The purposes of these investigations were to (1) evaluate tinnitus loudness measures of unskilled normal listeners asked to imagine that they are experiencing a constant monaural tonal tinnitus and (2) compare the performance of these listeners to that of a sample of patients with tinnitus. Subgroups of 24 patients participated in two investigations. Results suggest that (1) normal subjects asked to imagine a high-pitched, tonal tinnitus show significantly greater tinnitus loudness matching levels (a) when they do not have an external reference, (b) after a 1-week interval, and (c) for low-frequency matching tones; (2) patients with high-pitched tinnitus did not demonstrate statistically significant differences in tinnitus loudness judgments within or between sessions or frequencies; (3) tinnitus patients do not differ significantly from normals feigning tinnitus in the variability of tinnitus loudness matching levels within a single session (two measures) or after a 1-week interval (one measure); and (4) normals feigning tinnitus tended to choose significantly greater loudness matching levels than did tinnitus subjects.

Abbreviations: SL = sensation level, THI= Tinnitus Handicap Inventory
Effect of Stimulation Rate on Cochlear Implant Recipients' Thresholds and Maximum Acceptable Loudness Levels
Authors: Skinner Margaret W. , Holden Laura K. , Holden Timothy A. , Demorest Marilyn E.
Published: April 2022

Clinically, speech processor programs are created using electrical thresholds and maximum acceptable loudness levels (MALs) at several different stimulation rates to determine what rate will provide cochlear implant recipients with the best speech recognition when using fast-rate speech coding strategies. This study was designed to determine the difference in thresholds and MALs (expressed in the clinical unit, Current Level [CL]) for pairs of six rates spanning those available with the Nucleus 24 device (i.e., 250 to 2400 pps/ch) using monopolar, 25 μsec/phase stimulation. Test-retest measures of threshold and MAL for each rate were obtained from seven adult Nucleus 24 recipients on each of 11 electrodes. The difference in threshold and in MAL between pairs of rates was dependent on the absolute CL. Below approximately 190 CL, thresholds and MALs decreased with increasing rate; above 210 CL, there was little change in threshold or MAL with increasing rate. Based on these findings, an approach to estimating threshold and MAL from one rate to another is suggested, pending further research.

Abbreviations: ACE = advanced combination encoder, CIS = continuous interleaved sampling, CT = computed tomography, CL = current level, FDA = U.S. Food and Drug Administration, MALs = maximum acceptable loudness levels, NRT = neural response telemetry, pps/ch = pulses per second per channel, SPEAK = spectral peak speech coding strategy, WinDPS = Windows programming and diagnostic system
Principles of Functional Magnetic Resonance Imaging: Application to Auditory Neuroscience
Authors: Cacace Anthony T. , Tasciyan Talin , Cousins Joseph P.
Published: April 2022

Functional imaging based on magnetic resonance methods is a new research frontier for exploring a wide range of central nervous system (CNS) functions, including information processing in sensory, motor, cognitive, and linguistic systems. Being able to localize and study human brain function in vivo, in relatively high resolution and in a noninvasive manner, makes this a technique of unparalleled importance. In order to appreciate and fully understand this area of investigation, a tutorial covering basic aspects of this methodology is presented. We introduce functional magnetic resonance imaging (fMRI) by providing an overview of the studies of different sensory systems in response to modality-specific stimuli, followed by an outline of other areas that have potential clinical relevance to the medical, cognitive, and communicative sciences. The discussion then focuses on the basic principles of magnetic resonance methods including magnetic resonance imaging, MR spectroscopy, fMRI, and the potential role that MR technology may play in understanding a wide range of auditory functions within the CNS, including tinnitus-related activity. Because the content of the material found herein might be unfamiliar to some, we provide a broad range of background and review articles to serve as a technical resource.

Abbreviations: AL = anterior lateral, BOLD = blood oxygen level dependent, Cho = choline, CL = caudal lateral, CNS = central nervous system, CR = creatine, EEG = electroencephalography, EPI = echo planar imaging, ER = event related, ETS = echo-time shifting, fMRI = functional magnetic resonance imaging, FOV = field of view, G = Gauss, GET = gaze-evoked tinnitus, GRE = gradient-recalled echo, MEG = magnetoencephalography, ml = myo-inositol, ML = medial lateral, MRI = magnetic resonance imaging, MRS = magnetic resonance spectroscopy, NAA = N-acetylaspartate, NMR = nuclear magnetic resonance, PET = positron emission tomography, PRESTO = principles of echo shifting with a train of observations, RF = radio frequency, ROI = regions of interest, SE = spin echo, STEAM = short-TE stimulated echo acquisition mode, Τ = Tesla, TE = echo time, TR = repetition time
Ultrafast parallel single-pixel LiDAR with all-optical spectro-temporal encoding
Authors: Zang Zihan , Li Zhi , Luo Yi , Han Yanjun , Li Hongtao , Liu Xuanyi , Fu H. Y.
Published: April 2022

Light detection and ranging (LiDAR) with scanning beam has been widely used in autonomous driving and large-scale manufacturing, where the fast-changing scene is of great interest. However, the acquisition rate of current LiDAR is limited by beam steering speed and the round-trip delay, hindering the development of video-rate LiDAR. Here, we uniquely combine all-optical encoders with wavelength-division multiplexing devices to implement spectro-temporal encoding on the illumination light. Parallel detection and fast spectral scanning can be achieved with only one laser and one single photodetector. Our result shows the fastest single-pixel LiDAR to date, and the detection speed can be multiplied with scalability. We demonstrate 3.56-fold improvement of speed for a maximum of 75 m detection range compared with a serial LiDAR. A record acquisition rate of 21.38 MHz for a maximum of 25 m detection range is obtained. This approach has the potential to break the limitation on current ultrafast single-pixel LiDAR and opens a new paradigm for ultrafast-frame-rate imaging systems.
Design and characterization of innovative optical prism for four-degree-of-freedom fast steering mirror active laser compensation system
Authors: Liu Chien-Sheng , Tsai Chih-Hao
Published: April 2022

In this study, an innovative four-degree-of-freedom (4-DOF) compensation prism is designed for fast steering mirror active laser compensation systems. In addition to improving the disadvantages of the commercially available compensation systems, such as a larger number of components and longer optical paths, the proposed system has further enhanced the shortcoming of high sensitivity to the laser by using double Porro prisms as 4-DOF compensation prisms proposed in a previous study. The prism proposed in this study reduces the sensitivity to the laser while maintaining two translations and two rotations in 4-DOF control characteristic for laser, thereby improving the resolution of the system to control the laser. First, Zemax was used to build the overall system and evaluate the system characteristics. Then, the skew-ray tracing method and homogeneous coordinate transformation matrix were used to build the mathematical model of the compensation prism and analyze the sensitivity of the proposed prism to the laser. Finally, the closed-loop algorithm was established and the system was completely built on the optical table for experiments to compare the results between the laser before and after compensation by the proposed prism. In addition, the resolution of the proposed prism is compared with the double Porro prisms.
Stretchy and disordered: Toward understanding fracture in soft network materials via mesoscopic computer simulations
Authors: Tauber Justin , van der Gucht Jasper , Dussi Simone
Published: April 2022

Soft network materials exist in numerous forms ranging from polymer networks, such as elastomers, to fiber networks, such as collagen. In addition, in colloidal gels, an underlying network structure can be identified, and several metamaterials and textiles can be considered network materials as well. Many of these materials share a highly disordered microstructure and can undergo large deformations before damage becomes visible at the macroscopic level. Despite their widespread presence, we still lack a clear picture of how the network structure controls the fracture processes of these soft materials. In this Perspective, we will focus on progress and open questions concerning fracture at the mesoscopic scale, in which the network architecture is clearly resolved, but neither the material-specific atomistic features nor the macroscopic sample geometries are considered. We will describe concepts regarding the network elastic response that have been established in recent years and turn out to be pre-requisites to understand the fracture response. We will mostly consider simulation studies, where the influence of specific network features on the material mechanics can be cleanly assessed. Rather than focusing on specific systems, we will discuss future challenges that should be addressed to gain new fundamental insights that would be relevant across several examples of soft network materials.
An in situ micro-indentation apparatus for investigating mechanical parameters of thermal barrier coatings under temperature gradient
Authors: Luo Sangyu , Bai Haoran , Huang Ruizhe , Qu Zhaoliang , Lv Bowen , Fang Daining
Published: April 2022

Premature failure of thermal barrier coatings (TBCs) under a temperature gradient is an overriding concern in many applications, and their mechanical parameters are essential to failure analysis. In this study, an in situ micro-indentation apparatus, including a heating module, cooling module, and micro-indentation module, was developed to study the mechanical parameters of TBCs with a temperature gradient. The upper surface of the TBC was heated by radiation to simulate high-temperature service conditions, and the bottom surface was gas-cooled. Different temperature gradients are obtained by changing the velocity of the cooling gas. The temperatures through the thickness of the TBCs were analyzed by numerical simulations and experiments. During exposure to the temperature gradient, micro-indentation tests of the TBC samples were conducted to obtain their mechanical parameters. In situ micro-indentation tests at different cooling gas flow rates (0, 20, and 40 l/min) were performed on the TBCs. The elastic modulus and stress evolution of the TBCs were extracted by analyzing the load–displacement curves at different gas velocities. The elastic modulus remains almost constant with increasing velocity while the stress difference increases.
The ΔSCF method for non-adiabatic dynamics of systems in the liquid phase
Authors: Vandaele Eva , Mališ Momir , Luber Sandra
Published: April 2022

Computational studies of ultrafast photoinduced processes give valuable insights into the photochemical mechanisms of a broad range of compounds. In order to accurately reproduce, interpret, and predict experimental results, which are typically obtained in a condensed phase, it is indispensable to include the condensed phase environment in the computational model. However, most studies are still performed in vacuum due to the high computational cost of state-of-the-art non-adiabatic molecular dynamics (NAMD) simulations. The quantum mechanical/molecular mechanical (QM/MM) solvation method has been a popular model to perform photodynamics in the liquid phase. Nevertheless, the currently used QM/MM embedding techniques cannot sufficiently capture all solute–solvent interactions. In this Perspective, we will discuss the efficient ΔSCF electronic structure method and its applications with respect to the NAMD of solvated compounds, with a particular focus on explicit quantum mechanical solvation. As more research is required for this method to reach its full potential, some challenges and possible directions for future research are presented as well.
Short-period InAsSb-based strained layer superlattices for high quantum efficiency long-wave infrared detectors
Authors: Liu Jinghe , Donetski Dmitri , Kucharczyk Kevin , Zhao Jingze , Kipshidze Gela , Belenky Gregory , Svensson Stefan P.
Published: April 2022

Infrared detector barrier heterostructures with strained layer superlattice (SLS) absorbers with different periods were compared. The first was a reference using a conventional barrier heterostructure with a low temperature energy gap corresponding to a wavelength of 10 μm in a 2-μm-thick undoped absorber using a 10.9 nm period with InAs/InAsSb0.36 compositions grown directly on a GaSb substrate. The second structure, in contrast, used a significantly shorter 4.3 nm period absorber with InAsSb0.3/InAsSb0.55 compositions, similar energy gap, and absorber thickness, which were grown on a 6.2 Å lattice constant GaIn0.3Sb virtual substrate on GaSb. It was found that in the short period SLS, the vertical hole mobility and minority carrier lifetime in the temperature range of 80–150 K were a factor on 2–3 greater than in the reference structure. The improvement of the vertical hole mobility was attributed to the effect of hole delocalization. The latter results in an increase in the optical absorption coefficient and the quantum efficiency.
Numerical modeling of distributed combustion without air dilution in a novel ultra-low emission turbulent swirl burner
Authors: Füzesi Dániel , Malý Milan , Jedelský Jan , Józsa Viktor
Published: April 2022

Distributed combustion, often associated with the low-oxygen condition, offers ultra-low NOx emission. However, it was recently achieved without combustion air dilution or internal flue gas recirculation, using a distinct approach called mixture temperature-controlled combustion. Here, the fuel–air stream is cooled at the inlet to delay ignition and, hence, foster homogeneous mixture formation. This numerical study aims to understand its operation better and present a robust framework for distributed combustion modeling in a parameter range where such operation was not predicted before by any existing theory. Further, liquid fuel combustion was evaluated, which brings additional complexity. Four operating conditions were presented at which distributed combustion was observed. The reacting flow was modeled by flamelet-generated manifold, based on a detailed n-dodecane mechanism. The Zimont turbulent flame speed model was used with significantly reduced coefficients to achieve distributed combustion. The droplets of airblast atomization were tracked in a Lagrangian frame. The numerical results were validated by Schlieren images and acoustic spectra. It was concluded that the reactant dilution ratio remained below 0.25 through the combustion chamber, revealing that the homogeneous fuel–air mixture is the principal reason for excellent flame stability and ultra-low NOx emission without significant internal recirculation. The potential applications of these results are boilers, furnaces, and gas turbines.
Structure of turbulence in temporal planar jets
Authors: Cimarelli A. , Fregni A. , Mollicone J.-P. , van Reeuwijk M. , De Angelis E.
Published: April 2022

A detailed analysis of the structure of turbulence in a temporal planar turbulent jet is reported. Instantaneous snapshots of the flow and three-dimensional spatial correlation functions are considered. It is found that the flow is characterized by large-scale spanwise vortices whose motion is felt in the entire flow field. Superimposed to this large-scale motion, a hierarchy of turbulent structures is present. The most coherent ones take the form of quasi-streamwise vortices and high and low streamwise velocity streaks. The topology of these interacting structures is analyzed by quantitatively addressing their shape and size in the different flow regions. Such information is recognized to be relevant for a structural description of the otherwise disorganized motion in turbulent free-shear flows and can be used for the assessment of models based on coherent structure assumptions. Finally, the resulting scenario provides a phenomenological description of the elementary processes at the basis of turbulence in free-shear flows.
Excitation polarization-independent photo-induced restoration of inversion symmetry in Td-WTe2
Authors: Aoki Ryota , Uchida Kento , Tanaka Koichiro
Published: April 2022

Td-WTe2 is a topologically nontrivial material and exhibits a variety of physical properties, such as giant unsaturated magnetoresistance and the unconventional thermoelectric effect, due to its topological nature. It is also known to exhibit ultrafast topological phase transitions that restore its inversion symmetry by intense terahertz and mid-infrared pulses, and these properties demonstrate the possibility of ultrafast control of devices based on topological properties. Recently, a novel photo-induced topological phase transition by using polarization-controlled infrared excitation has been proposed, which is expected to control the material topology by rearranging the atomic orbitals near the Weyl point. To examine this topological phase transition, we experimentally studied the excitation-polarization dependence of the infrared-induced phase dynamics in a thin-layer of Td-WTe2. Time-resolved second harmonic generation (SHG) measurements showed that SHG intensity decreases after the infrared pump regardless of the polarization. Polarization-resolved infrared pump–probe measurements indicated that the polarization-selected excited state relaxes quite rapidly (i.e., within 10–40 fs). Considering these experimental results, we conclude that it is difficult to control the photo-induced phase transition through orbital-selective excitation owing to the rapid loss of carrier distribution created by polarization-selective excitation in thin-layer Td-WTe2 under our experimental condition. These results indicate that the suppression of the electron scattering process is crucial for experimentally realizing the photo-induced phase transition based on the polarization selection rule of the materials.
Electron g-factor determined for quantum dot circuit fabricated from (110)-oriented GaAs quantum well
Authors: Nakagawa T. , Lamoureux S. , Fujita T. , Ritzmann J. , Ludwig A. , Wieck A. D. , Oiwa A. , Korkusinski M. , Sachrajda A. , Austing D. G. , Gaudreau L.
Published: April 2022

The choice of substrate orientation for semiconductor quantum dot circuits offers opportunities for tailoring spintronic properties such as g-factors for specific functionality. Here, we demonstrate the operation of a few-electron double quantum dot circuit fabricated from a (110)-oriented GaAs quantum well. We estimate the in-plane electron g-factor from the profile of the enhanced inter-dot tunneling (leakage) current near-zero magnetic field. Spin blockade due to Pauli exclusion can block inter-dot tunneling. However, this blockade becomes inactive due to hyperfine interaction mediated spin flip-flop processes between electron spin states and the nuclear spin of the host material. The g-factor of absolute value ∼0.1 found for a magnetic field parallel to the direction [1¯10] is approximately a factor of four lower than that for comparable circuits fabricated from a material grown on widely employed standard (001) GaAs substrates and is in line with reported values determined by purely optical means for quantum well structures grown on (110) GaAs substrates.
Generalized master equation for charge transport in a molecular junction: Exact memory kernels and their high order expansion
Authors: Dan Xiaohan , Xu Meng , Yan Yaming , Shi Qiang
Published: April 2022

We derive a set of generalized master equations (GMEs) to study charge transport dynamics in molecular junctions using the Nakajima–Zwanzig–Mori projection operator approach. In the new GME, time derivatives of population on each quantum state of the molecule, as well as the tunneling current, are calculated as the convolution of time non-local memory kernels with populations on all system states. The non-Markovian memory kernels are obtained by combining the hierarchical equations of motion (HEOM) method and a previous derived Dyson relation for the exact kernel. A perturbative expansion of these memory kernels is then calculated using the extended HEOM developed in our previous work [M. Xu et al., J. Chem. Phys. 146, 064102 (2017)]. By using the resonant level model and the Anderson impurity model, we study properties of the exact memory kernels and analyze convergence properties of their perturbative expansions with respect to the system–bath coupling strength and the electron–electron repulsive energy. It is found that exact memory kernels calculated from HEOM exhibit short memory times and decay faster than the population and current dynamics. The high order perturbation expansion of the memory kernels can give converged results in certain parameter regimes. The Padé and Landau–Zener resummation schemes are also found to give improved results over low order perturbation theory.
Data-augmented turbulence modeling by reconstructing Reynolds stress discrepancies for adverse-pressure-gradient flows
Authors: Li Jin-Ping , Tang Deng-Gao , Yi Chen , Yan Chao
Published: April 2022

Turbulence modeling based on the Reynolds-averaged Navier–Stokes (RANS) method has been widely applied in industry, but its performance in some complex flows is far from satisfactory. The improvement of turbulence models based on the traditional framework has not made breakthrough progress for decades. In this study, a data-driven turbulence modeling framework based on the reconstruction of Reynolds stress discrepancies is used to aid in the improvement of turbulence models, with the Reynolds stresses of the shear-stress transport model being modified in the eigenspace. The large eddy simulation (LES) dataset of a set of bump cases is used to provide high-fidelity information on adverse-pressure-gradient flows for the modeling framework. First, the Reynolds stress tensors of RANS and LES are compared in terms of amplitude, shape, and orientation. Then, the random forest (RF) algorithm is employed to map the mean flow features to the Reynolds stress discrepancies. The well-trained RF model greatly improves the predictions of Reynolds stresses and other flow variables for the attachment and separation states and enables the numerical simulations to have predictive accuracy close to LES and computation time of the same order of magnitude as RANS.
Progress and perspectives in single-molecule optical spectroscopy
Authors: Adhikari Subhasis , Orrit Michel
Published: April 2022

We review some of the progress of single-molecule optical experiments in the past 20 years and propose some perspectives for the coming years. We particularly focus on methodological advances in fluorescence, super-resolution, photothermal contrast, and interferometric scattering and briefly discuss a few of the applications. These advances have enabled the exploration of new emitters and quantum optics; the chemistry and biology of complex heterogeneous systems, nanoparticles, and plasmonics; and the detection and study of non-fluorescing and non-absorbing nano-objects. We conclude by proposing some ideas for future experiments. The field will move toward more and better signals of a broader variety of objects and toward a sharper view of the surprising complexity of the nanoscale world of single (bio-)molecules, nanoparticles, and their nano-environments.
On the generalized Beltramian motion of the bidirectional vortex in a right-cylindrical cyclone with a hollow core
Authors: Cecil Orie M. , Majdalani Joseph
Published: April 2022

In this work, an exact inviscid solution is developed for the incompressible Euler equations in the context of a bidirectional, cyclonic flowfield in a right-cylindrical chamber with a hollow core. The presence of a hollow core confines the flow domain to an annular swirling region that extends into a toroid in three-dimensional space. The procedure that we follow is based on the Bragg–Hawthorne framework and a judicious assortment of boundary conditions that correspond to a wall-bounded cyclonic motion with a cylindrical core. At the outset, a self-similar stream function is obtained directly from the Bragg–Hawthorne equation under the premises of steady, axisymmetric, and inviscid conditions. The resulting formulation enables us to describe the bidirectional evolution of the so-called inner and outer vortex motions, including their fundamental properties, such as the interfacial layer known as the mantle; it also unravels compact analytical expressions for the velocity, pressure, and vorticity fields, with particular attention being devoted to their peak values and spatial excursions that accompany successive expansions of the core radius. By way of confirmation, it is shown that removal of the hollow core restores the well-established solution for a fully flowing cylindrical cyclone. Immediate applications of cyclonic flows include liquid and hybrid rocket engines, swirl-driven combustion devices, as well as a multitude of heat exchangers, centrifuges, cyclone separators, and flow separation devices that offer distinct advantages over conventional, non-swirling systems.