bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlling the ligands of CdZnTe quantum dots to design a super simple ratiometric fluorescence nanosensor for silver ion detection
Authors: Cui Haining , Wang Chengquan , Jia Suli , Qian Jing , Zhang Qi , Tian Yunmeng , Hao Nan , Wei Jie , Long Lingliang , Wang Kun
Published: August 2021

Schematic illustration of the working mechanism of the ratiometric fluorescence nanosensor for Ag+ detection.
The life-cycle environmental performance of producing formate via electrochemical reduction of CO2 in ionic liquid
Authors: Paulillo Andrea , Pucciarelli Martina , Grimaldi Fabio , Lettieri Paola
Published: August 2021

The environmental benefits of producing formate via electrochemical reduction of CO2 are not straightforward when compared with the conventional, fossil-based approach.
Absorption-enhanced EMI shielding using silver decorated three-dimensional porous architected reduced graphene oxide in polybenzoxazine composites
Authors: Kumaran R. , Kumar A. Vinaya , Ramaprabhu S. , Subramanian V.
Published: August 2021

The proliferation of wearable and portable electronic media has increased the demand for highly efficient materials that can be used to create shields against electromagnetic interference.
Theoretical modeling of structural superlubricity in rotated bilayer graphene, hexagonal boron nitride, molybdenum disulfide, and blue phosphorene
Authors: Kabengele Tilas , Johnson Erin R.
Published: August 2021

Structural superlubricity can be modeled successfully with planewave density-functional theory by constructing periodic Moiré patterns.
Microphase separation in helix–coil block copolymer melts: computer simulation
Authors: Glagolev M. K. , Glagoleva A. A. , Vasilevskaya V. V.
Published: August 2021

The phase diagram of helix–coil diblock copolymers was built via molecular dynamics simulation. Special morphologies such as cylinders with elliptical cross-sections on a distorted lattice and lamellae with strict helical packing were characterized.
Immune implication of an autophagy-related prognostic signature in uveal melanoma
Authors: Chuah Samuel , Chew Valerie
Published: August 2021

Uveal Melanoma (UM) is a rare cancer deriving from melanocytes within the uvea. It has a high rate of metastasis, especially to the liver, and a poor prognosis thereafter. Autophagy, an intracellular programmed digestive process, has been associated with the development and progression of cancers, with controversial pro- and anti-tumour roles. Although previous studies have been conducted on autophagy-related genes (ARGs) in various cancer types, its role in UM requires a deeper understanding for improved diagnosis and development of novel therapeutics. In the present study, Zheng et al. used univariate Cox regression followed by least absolute shrinkage and selection operator (Lasso) regression to identify a robust 9-ARG signature prognostic of survival in a total of 230 patients with UM. The authors used the Cancer Genome Atlas (TCGA) UM cohort as a training cohort (n=80) to identify the signature and validated it in another four independent cohorts of 150 UM patients from the Gene Expression Omnibus (GEO) repository (GSE22138, GSE27831, GSE44295 and GSE84976). This 9-ARG signature was also significantly associated with the enrichment of cancer hallmarks, including angiogenesis, IL6-KJAK-STAT3 signalling, reactive oxygen species pathway and oxidative phosphorylation. More importantly, this signature is associated with immune-related functional pathways and immune cell infiltration. Thus, this 9-ARG signature predicts prognosis and provides deeper insights into the immune mechanisms in UM, with potential implications for future immunotherapy.
Role of the HOXA cluster in HSC emergence and blood cancer
Authors: Abuhantash Mays , Collins Emma M. , Thompson Alexander
Published: August 2021

Hematopoiesis, the process of blood formation, is controlled by a complex developmental program that involves intrinsic and extrinsic regulators. Blood formation is critical to normal embryonic development and during embryogenesis distinct waves of hematopoiesis have been defined that represent the emergence of hematopoietic stem or progenitor cells. The Class I family of homeobox (HOX) genes are also critical for normal embryonic development, whereby mutations are associated with malformations and deformity. Recently, members of the HOXA cluster (comprising 11 genes and non-coding RNA elements) have been associated with the emergence and maintenance of long-term repopulating HSCs. Previous studies identified a gradient of HOXA expression from high in HSCs to low in circulating peripheral cells, indicating their importance in maintaining blood cell numbers and differentiation state. Indeed, dysregulation of HOXA genes either directly or by genetic lesions of upstream regulators correlates with a malignant phenotype. This review discusses the role of the HOXA cluster in both HSC emergence and blood cancer formation highlighting the need for further research to identify specific roles of these master regulators in normal and malignant hematopoiesis.
X-raying the Sco-Cen OB association: The low-mass stellar population revealed by eROSITA
Authors: Schmitt J. H. M. M. , Czesla S. , Freund S. , Robrade J. , Schneider P. C.
Published: August 2021

We present the results of the first X-ray all-sky survey (eRASS1) performed by the eROSITA instrument on board the Spectrum-Roentgen-Gamma observatory of the Sco-Cen OB association. Bona fide Sco-Cen member stars are young and are therefore expected to emit X-rays at the saturation level. The sensitivity limit of eRASS1 makes these stars detectable down to about a tenth of a solar mass. By cross-correlating the eRASS1 source catalog with the Gaia EDR3 catalog, we arrive at a complete identification of the stellar (i.e., coronal) source content of eROSITA in the Sco-Cen association, and in particular obtain for the first time a 3D view of the detected stellar X-ray sources. Focusing on the low-mass population and placing the optical counterparts identified in this way in a color-magnitude diagram, we can isolate the young stars out of the detected X-ray sources and obtain age estimates of the various Sco-Cen populations. A joint analysis of the 2D and 3D space motions, the latter being available only for a smaller subset of the detected stellar X-ray sources, reveals that the space motions of the selected population show a high degree of parallelism, but there is also an additional population of young, X-ray emitting and essentially cospatial stars that appears to be more diffuse in velocity space. Its nature is currently unclear. We argue that with our procedures, an identification of almost the whole stellar content of the Sco-Cen association will become possible once the final Gaia and eROSITA catalogs are available by the end of this decade. We furthermore call into question any source population classification scheme that relies on purely kinematic selection criteria.
Triggerpunkt, Akupunkturpunkt, Druckpunkt – „Who is who“?
Authors: Zohmann Andreas
Published: August 2021

Akupunkturpunkt, Triggerpunkt, Druckpunkt, Myogelose, Brennpunkt – die
Nomenklatur von diagnostisch und therapeutisch wirksamen Körperpunkten,
wie sie in der (tiermedizinischen) Literatur beschrieben werden, ist
vielfältig. Doch was ist damit jeweils gemeint? Und wie kommt es zu
diesem babylonisch anmutenden Sprachgewirr? Wir haben dies hinterfragt und
eingeordnet, um zu einer gewissen „Benennungskoordinierung“
beizutragen.
The Genetics of Uveal Melanoma: Overview and Clinical Relevance
Authors: Riechardt Aline Isabel , Kilic Emine , Joussen Antonia M.
Published: August 2021

Over the last ten years, much has been learnt about the genetic characteristics and genetic evolution of uveal melanoma. It has been shown that uveal melanoma differs fundamentally from non-uveal melanoma and is an independent genetic subtype. Compared to other tumours, uveal melanoma has a low mutational burden. There are recurring chromosomal aberrations with losses of 1p, 6q, 8p and 16q, gains of 6p and 8q, and the presence of monosomy 3. GNAQ, GNA11, PLCB4, CYSLTR2, MAPKAPK5, as well as mutations in BAP1, SF3B1, SRSF2 and EIF1AX, the latter being linked to a higher risk of metastasis, have been identified as significantly mutated genes. In rare cases, a BAP1 germline mutation may also be present. In addition to higher risk of uveal melanoma, this variant is also linked with other tumours. In this case, additional work-up, genetic counselling and screening of family members should be offered. While
the knowledge about the genetic characteristics of uveal melanoma is already routinely used for diagnostic and prognostic purposes, targeted genotype-dependent therapy of uveal melanoma is currently still missing.
Impfbereitschaft mit einem COVID-19-Vakzin und Einflussfaktoren.
Ergebnisse einer telefonischen Bevölkerungsbefragung
Authors: Haug Sonja , Schnell Rainer , Weber Karsten
Published: August 2021

Ziel Die Studie untersucht die Impfbereitschaft mit einem COVID-19-Vakzin
an einer Zufallsstichprobe der Gesamtbevölkerung und deren Determinanten
(wahrgenommene Risiken einer Erkrankung, wahrgenommene Nebenwirkungen und
allgemeine Einstellung zu Impfungen, Vertrauen in Institutionen,
soziostrukturelle Faktoren, Einfluss sozialer Bezugsgruppen).

Methodik Telefonische Ein-Themen-Bevölkerungsbefragung zur
Impfbereitschaft (n=2014) vor der Zulassung eines COVID-19-Vakzins in
Deutschland im November/Dezember 2020.

Ergebnisse Die Impfbereitschaft liegt bei etwa 67% und steigt mit
dem Anteil der impfbereiten Freunde und Bekannten und dem Vertrauen
gegenüber dem Robert-Koch-Institut, bei Zugehörigkeit zu einer
Risikogruppe und der Erwartung gefährlicher Konsequenzen bei einer
Erkrankung. Erfahrungen mit einer Infektion bei den Befragten oder in ihrer
sozialen Bezugsgruppe erhöhen die Impfbereitschaft. Männer haben
eine erhöhte Impfbereitschaft. Bei höherem Schulbildungsniveau
zeigt sich (mit Ausnahme der Personen mit Fachhochschulreife)
durchgängig eine höhere Impfneigung. Eine
Überschätzung der Wahrscheinlichkeit ernsthafter Nebenwirkungen
bei Grippeimpfungen senkt die Impfbereitschaft gegen COVID-19. Auffällig
ist der Befund einer erheblichen Überschätzung der
Häufigkeit von ernsthaften Impfnebenwirkungen bei
Influenza-Impfungen.

Schlussfolgerungen Es werden Implikationen für eine
zielgruppenadäquate Informationskampagne und Risikokommunikation
abgeleitet. Bestrebungen zur Förderung der Impfbereitschaft der
Bevölkerung sollten insbesondere benachteiligte
Bevölkerungsgruppen in den Fokus nehmen.
One-Pot Synthesis of 4H-Pyrano[3,2-c]coumarin Derivatives Catalyzed by Deep Eutectic Solvent
Authors: Xie Zongbo , Le Zhanggao , Li Hongxia , Yang Jiangnan , Zhu Xiao
Published: August 2021

4H-Pyrano[3,2-c]coumarin derivatives are an important class of pharmaceutical compounds that are expensive to prepare by previously reported methods. An efficient and green method was developed to obtain these derivatives using the deep eutectic solvent (DES) zinc chloride/acetamide (n:n = 1:4), which acted as both the catalyst and the solvent for the reaction. An aromatic aldehyde, 4-hydroxycoumarin, and cyanoacetate were used as the substrates. The DES, substrate molar ratio, diluent type, temperature, and reaction time were optimized to obtain the 4H-pyrano[3,2-c]coumarin derivatives from a range of aromatic aldehydes in a single step in moderate to high yields and under mild reaction conditions.
Asymmetric Synthesis of 3-Phenyl-2,3-dihydro-1H-pyrrolo[3,2-b]pyridine-3-carbonitriles Catalyzed by Phase-Transfer Catalyst Derived from tert-Leucine
Authors: Duan Haifeng , Lin Yingjie , Zhao Zhiqi , Wang Jingdong , Wei Zhonglin , Cao Jungang , Liang Dapeng
Published: August 2021

Chiral phase-transfer catalysts derived from tert-leucine were synthesized and used in the asymmetric synthesis of 4-azaindoline derivatives. By this method, both enantiomers of the corresponding products were obtained in excellent yield (up to 99%) with high enantio­selectivities (up to 91% ee) and diastereoselectivities (up to >99: 1 dr).
Asymmetric Synthesis of P-Stereogenic Secondary Phosphine ­Oxides (SPOs)
Authors: Glueck David S.
Published: August 2021

P-Stereogenic secondary phosphine oxides [SPOs, RR′P(O)H], valuable ligands for metal complexes in asymmetric catalysis, are also building blocks for other chiral phosphorus derivatives. This short review summarizes methods used for asymmetric synthesis of P-stereogenic SPOs.

1 Introduction

2 Configurational Stability of P-Stereogenic SPOs

3 Classical Resolution, HPLC Separation, and Dynamic Resolution

4 Synthesis via Chiral Auxiliaries

5 Kinetic Resolution

6 Conclusions and Outlook
α-Cationic Phosphines: from Curiosities to Powerful Ancillary Ligands
Authors: Alcarazo Manuel , Rugen Christian J.
Published: August 2021

The distinguishing feature of α-cationic phosphines is the presence of at least one substituent, normally (hetero)cyclic and positively charged, which is directly attached to the phosphorus atom. As result from this unique substitution pattern, the thus designed ligands depict significantly diminished donor properties if compared with their neutral counterparts. Thus, if in a hypothetical catalytic cycle, the step that determines the rate is facilitated by an increase of the electrophilicity at the metal center; then, the use of α-cationic ancillary phosphines can be highly beneficial. This fact, combined with their easy syntheses and stability, which allows an easy handling, make α-cationic phosphines a useful tool for the synthetic practitioner. Our research on the topic demonstrates that generally a remarkable ligand acceleration effect is observed when α-cationic phosphines are employed in Au(I)- and Pt(II)-promoted cycloisomerizations; moreover, in some cases even otherwise not operative transformations can be promoted. This Account describes how we entered into the topic, our efforts, and those of others to understand the coordination behavior of α-cationic phosphines and further develop their range of applications in catalysis; but it also identifies the drawbacks associated with their use, which limit their range of application.

1 Introduction

2 Polycationic Phosphines: Stronger Acceptors than Phosphites

3 Inconveniences Derived from the Use of (Poly)cationic phosphines

4 A Second Generation of Cationic Ligands: α-Pyridiniophosphines

5 Chiral α-Cationic Phosphines

6 α-Radical Phosphines and (Poly)cationic Phosphine Oxides

7 Conclusions and Outlook
Thumb Injuries and Instabilities. Part 1: Anatomy, Kinesiology, and Imaging Techniques of the Thumb
Authors: Blum Alain G. , van Holsbeeck Marnix T. , Bianchi Stefano
Published: August 2021

The unique anatomical characteristics of the thumb offer a broad range of motion and the ability to oppose thumb and finger, an essential function for grasping. The motor function of the thumb and its orientation make it particularly vulnerable to trauma. Pathologic lesions encountered in this joint are varied, and imaging techniques play a crucial role in injury detection and characterization. Despite advances in diagnostic accuracy, acute thumb injuries pose a challenge for the radiologist. The complex and delicate anatomy requires meticulous and technically flawless image acquisition. Standard radiography and ultrasonography are currently the most frequently used imaging techniques. Computed tomography is most often indicated for complex fractures and dislocations, and magnetic resonance imaging may be useful in equivocal cases. In this article, we present the relevant anatomy and imaging techniques of the thumb.
Osteoarthritis of the Wrist: Pathology, Radiology, and Treatment
Authors: Grunz Jan-Peter , Gietzen Carsten Herbert , Christopoulos Georgios , van Schoonhoven Jörg , Goehtz Florian , Schmitt Rainer , Hesse Nina
Published: August 2021

Osteoarthritis (OA) is a degenerative disease that can manifest in any synovial joint under certain conditions. It leads to destruction of articular cartilage and adjacent bone, as well as formation of osteophytes at the edges of afflicted joint surfaces. Regarding the wrist, typical degenerative arthritis affects particular joints at a specific patient age, due to asymmetric load distribution and repetitive microtrauma. However, in the presence of instability or systemic diseases, early-onset degeneration can also impair the range of motion and grip strength in younger patients. Although advanced stages of OA display characteristic signs in radiography, the detection of early manifestations frequently requires computed tomography or magnetic resonance imaging (in some cases with additional arthrography). If a wrist becomes unstable, timely diagnosis and precise treatment are essential to prevent rapid disease progression. Therefore, close collaboration between radiologists and hand surgeons is obligatory to preserve the carpal function of patients.
Postoperative Imaging of Ulnar Wrist Pain
Authors: Cerezal Luis , Llopis Eva , Canga Ana , Piñal Francisco Del
Published: August 2021

Ulnar wrist pain, caused by a broad spectrum of bone and soft tissue injuries, is the most common clinical condition of the wrist. Multiple surgical techniques and their variants in the treatment of these injuries are constantly evolving. Postoperative evaluation of the wrist for many surgeons is limited to serial clinical and radiographic monitoring. However, imaging methods such as ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and arthrographic techniques (arthrographic CT and arthrographic MRI) play a fundamental role in diagnosing and managing postsurgical complications.

The several critical aspects in evaluating the postsurgical wrist imaging spectrum are familiarity with the surgical techniques, knowledge of the original clinical problem, understanding the strength and limitations of the different radiologic modalities, and effective communication between surgeon and radiologist.
Complications of Percutaneous Biliary Procedures
Authors: Molina Heather , Chan Maye M. , Lewandowski Robert J. , Gabr Ahmed , Riaz Ahsun
Published: August 2021

Percutaneous biliary and gallbladder drainage is routinely performed by interventional radiology. These pathologies and techniques are well described in the literature and in this issue. The purpose of this review is to focus on the recognition and management of complications. Percutaneous biliary drains can have a variety of complications which can range from minor skin issues to more serious and complex bleeding issues. Advancements in imaging and techniques improve the safety profile of percutaneous biliary and gallbladder interventions.
Effect of Surgical Design Variations on the Knee Contact Behavior during Anterior Cruciate Ligament Reconstruction
Authors: Adouni Malek , Faisal Tanvir , Dhaher Yasin
Published: August 2021

In this study, we aimed to develop an in-silico synthesis of the effect of critical surgical design parameters on articular contact behavior for a bone-patellar-tendon-bone anterior cruciate ligament reconstruction (ACL-R) surgery. A previously developed finite element model of the knee joint consisting of all relevant soft tissues was employed. The knee model was further updated with additional features to develop the parametric FE model of the biomechanical experiments that depicted the ACL-R surgery. The parametricity was created involving femoral tunnel architecture (orientations and locations) and graft fixation characteristics (pretension and angle of fixation). A global sensitivity analysis based on variance decomposition was used to investigate the contribution of the surgical parameters to the uncertainty in response to the ACL-R joint. Our examinations indicated that the total contact force was primarily influenced by either combined or individual action of the graft pretension and fixation angle, with a modest contribution of the graft insertion sites. The joint contact center and area were affected mainly by the angle of fixation and the tunnel placements. Graft pretension played the dominant role in the maximum contact pressure variability, an observation that has been well-documented in the literature. Interestingly, the joint contact behavior was almost insensitive to the tunnel's coronal and sagittal orientations. Our data provide an evaluation of how the surgical parameters affect the knee joint's contact behavior after ACL-R and may provide additional information to better explain the occurrence of osteoarthritis as an aftermath of such surgery.
Complications of Pregnancy in Adolescents
Authors: Todhunter Logan , Hogan-Roy Megan , Pressman Eva K.
Published: August 2021

Teenage pregnancy is a complex issue that can have negative socioeconomic and health outcomes. About 11% of births worldwide are by adolescents aged between 15 and 19 years and middle- and low-income countries account for more than 90% of these births. Despite the downward trend in international adolescent pregnancy rates, 10 million unplanned adolescent pregnancies occur annually. Adolescents are also at increase risks of poor obstetric outcomes including preterm delivery, low birth weight, eclampsia, postpartum hemorrhage, anemia, and infant, as well as maternal morbidity. Important additional considerations include increased risk of depression, poor social support, and the need for a multidisciplinary approach to their obstetric care. We look to highlight both the unique socioeconomic and medical factors to consider when caring for these patients and demonstrate that these factors are intertwined.
Dynamics of solutions of a fractional NLS system with quadratic interaction
Authors: Esfahani Amin
Published: August 2021

The purpose of this article is twofold. First, we study the existence and asymptotic behavior of ground states of a fractional Schrodinger system with quadratic interaction. Second, we give some conditions, in terms of the mass and energy of the ground states, under which the solutions of the associated initial value problem have the uniform bound or may blow up in finite time. As a corollary, we show the strong instability of the ground states.
Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarator
Authors: Lunsford R. , Killer C. , Nagy A. , Gates D. A. , Klinger T. , Dinklage A. , Satheeswaran G. , Kocsis G. , Lazerson S. A. , Nespoli F. , Pablant N. A. , von Stechow A. , Alonso A. , Andreeva T. , Beurskens M. , Biedermann C. , Brezinsek S. , Brunner K. J. , Buttenschön B. , Carralero D. , Cseh G. , Drewelow P. , Effenberg F. , Estrada T. , Ford O. P. , Grulke O. , Hergenhahn U. , Höfel U. , Knauer J. , Krause M. , Krychowiak M. , Kwak S. , Langenberg A. , Neuner U. , Nicolai D. , Pavone A. , Puig Sitjes A. , Rahbarnia K. , Schilling J. , Svensson J. , Szepesi T. , Thomsen H. , Wauters T. , Windisch T. , Winters V. , Zhang D. , Zsuga L. ,   W7-X team
Published: August 2021

Pulsed injections of boron carbide granules into Wendelstein 7-X stellarator (W7-X) plasmas transiently increase the plasma stored energy and core ion temperatures above the reference W7-X experimental programs by up to 30%. In a series of 4 MW electron cyclotron resonance heating experiments, the PPPL Probe Mounted Powder Injector provided 50 ms bursts of 100 μm granules every 350 ms at estimated quantities ranging from approximately 1 mg/pulse to over 30 mg/pulse. For each injection, the stored energy was observed to initially drop and the radiated power transiently increased, while the radial electron density profile rose at the edge as material was assimilated. Once the injected boron carbide was fully absorbed, the density rise transitioned to the core while the stored energy increased above the previous baseline level by an amount linearly correlated with the injection quantity. During the injection, the ion temperature gradient steepened with peak core ion temperatures observed to increase from a nominal 1.7 keV to over 2.6 keV for the largest injection amounts. Enhanced performance is accompanied by a reversal of the radial electric field at ρ < 0.3, indicating that the core transport has switched to the ion root. These observations are suggestive of a change in transport and provide further evidence that externally induced profile modifications provide a possible path to enhanced W7-X performance metrics.
A new and alternative look at nonlinear Alfvénic states
Authors: Mahajan Swadesh M.
Published: August 2021

The formulation for studying nonlinear Alfvénic states, sustainable in Hall Magnetohydrodynamics (HMHD), becomes considerably simpler and more tractable when circularly polarized Beltrami vectors (the eigenstates of linear HMHD) are used as the basis functions. Nonlinear HMHD is, then, reduced to a rather simple looking set of scalar equations from which a model problem of three interacting Beltrami modes is formulated and analytically solved. The triplet interactions span a variety of familiar nonlinear processes leading to a redistribution as well as periodic exchange of energy. The energy exchange processes (whose strength is measured by an energy exchange/depletion time) will, perhaps, play a dominant role in determining the spectral content of an eventual Alfvénic state. All nonlinearities (sensitive functions of the interacting wave vectors) operate at par, and none is dominant over any substantial region of k-space; their intricate interplay prevents a “universal” picture from emerging; few generalizations on the processes that may, for instance, lead to a turbulent state, are possible. However, the theory can definitely claim: (1) the energy tends to flow from lower to higher k and (2) the higher kz (in the direction of the ambient magnetic field) components of a mode with a given k are depleted/oscillate faster—in some cases much faster. It is noteworthy that the mode coupling is the strongest (with the shortest depletion time) when the participating wave vectors are nearly perpendicular; perhaps, an expected consequence of the curl (cross product) nonlinearities. Numerical simulations will be necessary to help create a fully reliable picture.
An expectation–maximization algorithm for positron emission particle tracking
Authors: Manger Sam , Renaud Antoine , Vanneste Jacques
Published: August 2021

We develop a new algorithm for the tracking of radioactive particles using Positron Emission Particle Tracking (PEPT). The algorithm relies on the maximization of the likelihood of a simple Gaussian mixture model of the lines of response associated with positron annihilation. The model includes a component that accounts for spurious lines caused by scattering and random coincidence, and it treats the relative activity of particles as well as their positions as parameters to be inferred. Values of these parameters that approximately maximize the likelihood are computed by the application of an expectation–maximization algorithm. A generalization of the model that includes the particle velocities and accelerations as additional parameters takes advantage of the information contained in the exact timing of positron annihilations to reconstruct pieces of trajectories rather than fixed positions, with clear benefits. We test the algorithm on both simulated and experimental data. The results show the algorithm to be highly effective for the simultaneous tracking of many particles (up to 80 in one test). It provides estimates of particle positions that are easily mapped to entire trajectories and handles a variable number of particles in the field of view. The ability to track a large number of particles robustly offers the possibility of a dramatic expansion of the scope of PEPT.
Generic features in the spectral decomposition of correlation matrices
Authors: Stepanov Yuriy , Herrmann Hendrik , Guhr Thomas
Published: August 2021

We show that correlation matrices with particular average and variance of the correlation coefficients have a notably restricted spectral structure. Applying geometric methods, we derive lower bounds for the largest eigenvalue and the alignment of the corresponding eigenvector. We explain how and to which extent a distinctly large eigenvalue and an approximately diagonal eigenvector generically occur for specific correlation matrices independent of the correlation matrix dimension.
Enhanced transverse piezoelectric properties by composition and poling electric field induced phase transition in PIN–PMN–PT single crystal near morphotropic phase boundary
Authors: Ma Ming , Xia Song , Song Kexin , Guo Haisheng , Xu Zhuo , Li Zhenrong
Published: August 2021

A monoclinic phase is the bridge between the rhombohedral and tetragonal phases in the Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT) single crystal near the morphotropic phase boundary (MPB), which is related to the superior piezoelectric performance. In this paper, the different phase transition process in the unpoled PIN–PMN–PT single crystals near MPB induced by composition variation was presented first. Based on this, direct current poling (DCP) and alternating current treatment (ACT) were applied on these samples. Also, the crystals by DCP–ACT have shown a more complex ferroelectric phase transition process than that by DCP, which is related to the induced monoclinic phase by applying an AC electric field. The transverse piezoelectric properties of the PIN–PMN–PT single crystal with various compositions by DCP and DCP–ACT were compared. ACT enhanced the electromechanical coupling coefficient k31, elastic compliance constant S11E, and dielectric permittivity ε33T/ε0 of the pre-DCP PIN–PMN–PT single crystals in the macrorhombohedral phase. As a result, the transverse piezoelectric constant d31 of the crystals with various compositions was enhanced to be −1240, −1663, and −1252 pC/N by DCP–ACT, which were 61.7%, 73.0%, and 60.8% higher than that by DCP. However, ACT has little effect on the pre-DCP PIN–PMN–PT crystal with macrocoexistence of rhombohedral and monoclinic phases. The AC electric field could be a useful way for tuning the coexistence of rhombohedral and monoclinic phases in the PIN–PMN–PT crystal near MPB to achieve high transverse piezoelectric performance.
Domain boundaries in incommensurate epitaxial layers on weakly interacting substrates
Authors: Xiang Yu , Xie Songchun , Lu Zonghuan , Wen Xixing , Shi Jian , Washington Morris , Wang Gwo-Ching , Lu Toh-Ming
Published: August 2021

There has been increasing interest in the fabrication of thin film materials with mixed dimensions, in particular, 2D to 3D and 3D to 2D heterostructures. Often, if the interface interaction is weak, the lattice matching criterion between the substrate and overlayer can be lifted. If the overlayer lattice is completely relaxed, it can form an incommensurate film on the mismatched substrate. In this work, we show that domain boundaries are inherent in the incommensurate epitaxial films due to random nucleation sites of domains in an overlayer. The nature and origin of the incommensurate domain boundaries are different from the conventional dislocation boundaries that come from the relaxation of strain due to film–substrate lattice mismatch. We propose that the formation of such domain boundaries can be studied through Voronoi tessellation. Using a case study of monolayer WS2 on sapphire (2D on 3D), we show the formation of domain boundaries that compared well with a recent experiment reported in the literature. In the Voronoi tessellation, we also show quantitatively that the average domain size depends on the density of nucleation sites. The conclusion of this case study may be generalized to any incommensurate epitaxial films when the interface interaction is weak.
Toward the understanding of water-in-salt electrolytes: Individual ion activities and liquid junction potentials in highly concentrated aqueous solutions
Authors: Degoulange Damien , Dubouis Nicolas , Grimaud Alexis
Published: August 2021

Highly concentrated electrolytes were recently proposed to improve the performances of aqueous electrochemical systems by delaying the water splitting and increasing the operating voltage for battery applications. While advances were made regarding their implementation in practical devices, debate exists regarding the physical origin for the delayed water reduction occurring at the electrode/electrolyte interface. Evidently, one difficulty resides in our lack of knowledge regarding ion activity arising from this novel class of electrolytes, which is necessary to estimate the Nernst potential of associated redox reactions, such as Li+ intercalation or the hydrogen evolution reaction. In this work, we first measured the potential shift of electrodes selective to Li+, H+, or Zn2+ ions from diluted to highly concentrated regimes in LiCl or LiTFSI solutions. Observing similar shifts for these different cations and environments, we establish that shifts in redox potentials from diluted to highly concentrated regimes originate in large from an increased junction potential, which is dependent on the ion activity coefficients that increase with the concentration. While our study shows that single ion activity coefficients, unlike mean ion activity coefficients, cannot be captured by any electrochemical means, we demonstrate that the proton concentration increases by one to two orders of magnitude from 1 to 15–20 mol kg−1 solutions. Combined with the increased activity coefficients, this phenomenon increases the activity of protons and thus increases the pH of highly concentrated solutions which appears acidic.
Routes to realize the axion-insulator phase in MnBi2Te4(Bi2Te3)n family
Authors: Zhao Yufei , Liu Qihang
Published: August 2021

Axion, first postulated as a hypothetical particle in high-energy physics, is now extended to describe a novel topological magnetoelectric effect derived from the Chern–Simons theory in condensed matter systems. The recent discovered intrinsic magnetic topological insulators (MTIs) MnBi2Te4 and its derivatives have attracted great attention because of their potential as a material platform to realize such a quantized axion field. Since the magnetic exchange gap can bring the “half-quantized” anomalous Hall effect at the surface, an axion insulator manifests as quantum anomalous Hall and zero Hall plateau effects in the thin films. However, many puzzles about this material family remain elusive yet, such as the gapless surface state and the direct experimental evidence of the axion insulator. In this Perspective, we discuss the preconditions, manifestations, and signatures of the axion-insulator phase, in the context of the development of the natural magnetic topological heterostructure MnBi2Te4(Bi2Te3)n family with various intriguing quantum phenomena. Recent theoretical and experimental efforts regarding the intrinsic magnetic topological insulators are summarized here to pave the way for this phenomenally developing field.
Quantum efficiency and oscillator strength of InGaAs quantum dots for single-photon sources emitting in the telecommunication O-band
Authors: Große Jan , Mrowiński Paweł , Srocka Nicole , Reitzenstein Stephan
Published: August 2021

We demonstrate experimental results based on time-resolved photoluminescence spectroscopy to determine the oscillator strength and the internal quantum efficiency (IQE) of InGaAs quantum dots (QDs). Using a strain-reducing layer, these QDs can be employed for the manufacturing of single-photon sources emitting in the telecom O-Band. The oscillator strength and IQE are evaluated by determining the radiative and non-radiative decay rates under the variation of the optical density of states at the position of the QD for InGaAs QDs emitting at wavelengths below 1 μm. For this purpose, we perform measurements on a QD sample for different thicknesses of the capping layer realized by a controlled wet-chemical etching process. From numeric modeling of the radiative and non-radiative decay rates dependence on the capping layer thickness, we determine an oscillator strength of 24.6 ± 3.2 and a high IQE of (85 ± 10)% for the long-wavelength InGaAs QDs.
Hydrodynamic benefit of cephalic fins in a self-propelled flexible manta ray
Authors: Zhao Jiazhen , Mao Qian , Pan Guang , Huang QiaoGao , Sung Hyung Jin
Published: August 2021

The hydrodynamic benefit of cephalic fins in manta ray was explored using the penalty immersed boundary method. When manta rays feed, they open their cephalic fins and lower them to their mouth. As they swim forward, the cephalic fins are straightened in the forward direction. The smooth body of manta rays was modeled as a flexible plate. A self-propelled flexible plate was realized by enforcing a prescribed harmonic oscillation in the vertical direction but allowing the plate to move freely in the horizontal direction. Simulations without cephalic fins were also performed for comparison. Vortical structures and pressure distributions were visualized to elucidate the hydrodynamic benefits of cephalic fins. The fins generated streamwise vortices that resulted in negative pressure and enhanced the average cruising speed and thrust. The effect of the gap distance (g/L, where g is the gap distance between the two cephalic fins and L is the length of the plate) was examined in detail. The underlying propulsion mechanism was analyzed by examining the phase of the heaving stroke. The effects of the g/L were scrutinized by visualizing the contours of vorticity (ωx, ωy, ωz) and pressure (p) around the flexible plate. A maximum cruising speed was obtained at g/L = 0.6, where the average cruising speed increased by more than 62.8%.
Theory-based prediction of separation angle and peak pressure for laminar separated hypersonic compression corner flows
Authors: Li Xian-Dong , Yu Yong-Liang , Bao Lin
Published: August 2021

Interactions between shock waves and the boundary layer will cause high pressure loads and severe heating locally on the material surface in hypersonic separation–reattachment flows. In this paper, theoretical modeling is employed to study the separation angle and peak pressure of hypersonic compression corner flows with separated regions at low-to-medium Reynolds number. According to the characteristics of wall pressure distribution and flow field structures, an equivalent double shocks inviscid flow model for peak pressure is introduced. Based on this model, combining the “free-interaction theory,” formulas for the separation angle and peak pressure with freestream parameters (Mach number and Reynolds number) and the geometry corner angle are derived, and the reasonability and effectiveness are also shown by the numerical data provided by the direct simulation Monte Carlo method. It is revealed that the separation angle is almost independent of the freestream Mach number, and the ratio of peak pressure to freestream pressure is approximately proportional to the square of the freestream Mach number under strong viscous interaction conditions. Moreover, it is indicated that present theoretical results can be extended to axisymmetric flows through the discussion of hypersonic separated flows generated by a hollow cylinder-flare geometry.
Role of deep levels and barrier height lowering in current-flow mechanism in 150 μm thick epitaxial n-type 4H–SiC Schottky barrier radiation detectors
Authors: Kleppinger Joshua W. , Chaudhuri Sandeep K. , Karadavut OmerFaruk , Mandal Krishna C.
Published: August 2021

Schottky barrier detectors (SBDs) require larger surface areas than conventional electronics to increase the detection efficiency although such SBDs manifest large diode ideality factors due to inhomogeneous areal distribution of surface barrier height (SBH). Inhomogeneous SBH distributions lead to various current flow mechanisms in SBDs, which need to be identified to optimize detector performance. In this Letter, we identify the current flow mechanism in large area Schottky barrier diodes for radiation detection fabricated on 150 μm thick n-4H–SiC epitaxial layers. The analysis of temperature-dependent forward current–voltage (I–V–T) characteristics of SBDs revealed two linear regions in current–voltage curves up to 450 K, one corresponding to the current flow through a low barrier patch, while the other corresponds to that of average barrier distribution. Applying a SBH distribution model to the reverse I–V–T characteristics, an activation energy of 0.76 eV for the current flow over the Schottky barrier was calculated. The activation energy did not directly correspond to any of the defect levels observed from the deep level transient spectroscopy (DLTS). Above 450 K, a Schottky type barrier lowering suggested a current flow through a low barrier patch of ≈ 0.8 eV. The absence of any SBH lowering below 450 K indicated that the current corresponded to a neutrally charged trap level at ≈ 0.6 eV below the conduction band edge, which was consistent with DLTS measurements revealing the presence of an electron trap level Z1/2 at 0.59 eV below the conduction band edge.
Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis
Authors: Sah Pratha , Fitzpatrick Meagan C. , Zimmer Charlotte F. , Abdollahi Elaheh , Juden-Kelly Lyndon , Moghadas Seyed M. , Singer Burton H. , Galvani Alison P.
Published: August 2021

Significance

Asymptomatic infections have been widely reported for COVID-19. However, many studies do not distinguish between the presymptomatic stage and truly asymptomatic infections. We conducted a systematic review and meta-analysis of COVID-19 literature reporting laboratory-confirmed infections to determine the burden of asymptomatic infections and removed index cases from our calculations to avoid conflation. By analyzing over 350 papers, we estimated that more than one-third of infections are truly asymptomatic. We found evidence of greater asymptomaticity in children compared with the elderly, and lower asymptomaticity among cases with comorbidities compared to cases with no underlying medical conditions. Greater asymptomaticity at younger ages suggests that heightened vigilance is needed among these individuals, to prevent spillover into the broader community.
Final report on supplementary comparison on step heights standards (APMP.L-S7)
Authors: Sharma Rina , Moona Girija , Tonmueanwai Anusorn , Buajarern Jariya , Shihua Wang , Matus Michael , Doi Takuma , Sugawara Kentaro
Published: August 2021

Main text

This intercomparison is carried out for step height standards with nominal step sizes 8 nm, 18 nm, 88 nm and 10 µm using non-contact measurement methods, with four participating NMIs. Measurement observation from the pilot laboratory exhibit significant stability of step height standards. For each step height standard, the supplementary comparison reference value (SCRV) is determined using weighted mean, followed by calculation of En values for outlier identification. Further the outliers were excluded based upon the Birge Ratio consistency test. Measurement results from all the participating NIMs have been compiled in this report.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Photoionization of a quantum grating formed by a single atom
Authors: Zhang S F , Najjari B , Ma X
Published: August 2021

When an atom passes through a macroscopic diffraction grating its wave function acquires a regular space structure and its collision by another particle can be thought of as scattering, of the latter, on a grating composed of a single atom (hereafter termed as ‘quantum-grating’). Photoionization of such a ‘quantum grating’ unveils interference features and in particular a striking difference in the photoelectron and recoil ion spectra which no longer ‘mirroring’ each other as in the case of photoionization of atoms or molecules. We show that complete information about the macroscopic diffraction grating is directly contained in the recoil ion spectra while only partly exhibited in the spectra of the electron.
Effect of NaOH molarities to the microstructure and sodium storage performance of the Sn-MOF derived SnO2 microporous rod
Authors: Lu XiaoXiao , Xiong QinQin , Yao ZhuJun , Qiu JieQiong , Xu YuanKang , Shan RuiHao , He XinTong , Cai YuRong
Published: August 2021

In this study, we demonstrated a facile method to prepare a novel SnO2 microporous rod with various microstructures by controlling NaOH molarities in precursor synthesis processes. Four different molarities of NaOH solution (0.005 M, 0.048 M, 0.12 M and 0.5 M) were used together with o-phthalic acid in Sn-MOF synthesis to determine the effect of ligand [o-C6H4

CO

2

2

2
−

] concentration on microstructure evolution. It was found that increasing NaOH molarity can effectively decrease the size of Sn-MOF rods. Then, the SnO2 microporous rods were obtained by calcinating the as-prepared Sn-MOF as microstructures. Under an optimized experimental condition (NaOH molarity of 0.12 M), the SnO2 rods shows a modest initial coulombic efficiency of 61.3% with a high reversible sodium storage capacity of 503 mAh g−1 after 150 cycles at 50 mA g−1. Moreover, an impressive reversible sodium storage capacity of 206 mAh g−1 can be obtained at long-term cycling performance (800 cycles at current density of 2 A g−1). Effects of morphologies to electrochemical performances have been further discussed in aspects of intrinsic resistance, pseudocapacitive contribution, surface area and porous structure and microstructural stability, and the enhanced electrochemical performance could be attributed to factors of enhanced pseudocapacitive charge contribution, optimized microstructures, and structural stability, which ensure the SnO2−0.12 M to have a good rate performance and cyclability. This nanoscale-engineering method adopted here could be a promising path to fabricate SnO2-based anodes with novel microstructures for sodium storage applications.
High-temperature superconducting screens for magnetic field-error cancellation in accelerator magnets
Authors: Bortot L , Mentink M , Petrone C , Van Nugteren J , Deferne G , Koettig T , Kirby G , Pentella M , Perez J C , Pincot F O , De Rijk G , Russenschuck S , Verweij A P , Schöps S
Published: August 2021

Accelerators magnets must have minimal magnetic field imperfections to reduce particle-beam instabilities. In the case of coils made of high-temperature superconducting (HTS) tapes, the magnetization due to persistent currents adds an undesired field contribution, potentially degrading the magnetic field quality. In this paper we study the use of superconducting screens based on HTS tapes for reducing the magnetic field imperfections in accelerator magnets. The screens exploit the magnetization by persistent currents to cancel out the magnetic field error. The screens are aligned with the main field component, such that only the undesired field components are compensated. The screens are self-regulating, and do not require any externally applied source of energy. Measurements in liquid nitrogen at

77

 

K

show for dipole-field configurations a significant reduction of the magnetic field error up to a factor of four. The residual error is explained via numerical simulations accounting for the geometric defects in the HTS screens, achieving satisfactory agreement with experimental results. Simulations show that if screens are increased in width and thickness, and operated at

4.5

 

K

, field errors may be eliminated almost entirely for the typical excitation cycles of accelerator magnets.