bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between functional genetic variants in retinoid X receptor-α/γand the risk of gestational diabetes mellitus in a southern Chinese population
Authors: Yu Xiang-yuan , Song Li-ping , Zheng Hui-ting , Wei Shu-dan , Wen Xiao-lan , Huang Bo , Liu Da-bin
Published: October 2021

To clarify the effect of retinoid X receptor-α/γ (RXR-α/γ) genes functional genetic variants (RXR-α rs4842194 G>A, RXR-γ rs100537 A>G and rs2134095 T>C) on the risk of gestational diabetes mellitus (GDM), a case–control study with 573 GDM patients and 740 pregnant women with normal glucose tolerance was performed in Guangxi area of China. An odds ratio (OR) with its corresponding 95% confidence interval (CI) was used to assess the strengths of the association between genetic variation and GDM. After adjustment of age and pre-BMI, the logistic regression analysis showed that the rs2134095 was significantly associated with GDM risk (CC vs. TT/TC: adjusted OR = 0.71, 95% CI = 0.56–0.90) in all subjects, and this result remained highly significant after Bonferroni’s correction for multiple testing (P=0.004). The stratified analysis showed that rs2134095 was significantly associated with the risk of GDM among age > 30 years (adjusted OR = 0.61, 95% CI = 0.39–0.97), BMI > 22 kg/m2 (adjusted OR = 0.46, 95% CI = 0.30–0.70), systolic blood pressure (SBP) > 120 mmHg (adjusted OR = 1.96, 95% CI = 1.14–3.36), glycosylated hemoglobin A1c (HbA1c) < 6.5% (adjusted OR = 1.41, 95% CI = 1.11–1.78), TG ≤ 1.7 mmol/l (adjusted OR = 2.57, 95% CI = 1.45–4.53), TC ≤ 5.18 mmol/l (adjusted OR = 1.58, 95% CI = 1.13–2.22), high-density lipoprotein cholesterol (HDL-c) ≤ 1.5 mmol/l (adjusted OR = 1.70, 95% CI = 1.16–2.49) and low-density lipoprotein cholesterol (LDL-c) > 3.12 mmol/l (adjusted OR = 1.47, 95% CI = 1.08–2.00) subjects, under the recessive genetic model. We also found that rs2134095 interacted with age (Pinteraction=0.039), pre-BMI (Pinteraction=0.040) and TG (Pinteraction=0.025) influencing individual’s genetic susceptibility to GDM. The rs2134095 T>C is significantly associated with the risk of GDM by effect of a single locus and/or complex joint gene–gene and gene–environment interactions. Larger sample-size and different population studies are required to confirm the findings.
Sub‐bitstream packing based lightweight tiled streaming for 6 degree of freedom immersive video
Authors: Jeong Jong‐Beom , Lee Soonbin , Ryu Eun‐Seok
Published: October 2021

The MPEG immersive video (MIV) has been designed to remove the redundancies of multi‐view videos and merge the residuals into two textures and two geometry videos; therefore, four bitstreams and video decoders are required to provide six degrees of freedom (6DoF) in virtual reality (VR) in MIV. This letter proposes a sub‐bitstream packing method and realisation in tiled streaming for MIV to provide a single bitstream for legacy systems that have a single decoder without an increase in the server‐side storage. The proposed method divided the input videos into tiles in the compressed‐domain to accomplish two goals: (i) generate a merged bitstream using the existing four bitstreams for legacy systems and (ii) improve the quality of an immersive video by disabling the deblocking filter. For a player with one or few numbers of decoders, the extracted tile sub‐streams were merged by the proposed four specific mixed‐quality tiling and packing methods using a motion‐constrained tile set (MCTS), while complying with the high‐efficiency video coding (HEVC) standard. Experimental results demonstrated that the proposed sub‐stream packing method required a single decoder and exhibited 17.40% decoding time and 0.81% bjontegaard‐delta rate (BD‐rate) savings on Y‐PSNR saving compared to the non‐tiled streaming method.
Electromagnetic design and thermal analysis of module combined permanent magnet motor with wrapped type for mine ball mill
Authors: Xu Yingying , Zhang Bingyi , Feng Guihong
Published: October 2021

With the large‐scale development of the ball mill, the direct‐drive gearless ball mill has emerged, eliminating the limitation of the transmission torque of large gear. However, it is difficult to process, transport, install and maintain the gearless ball mill because of its vast volume, and the coils cannot be decoupled freely. Therefore, this work proposes a module combined permanent magnet motor with wrapped type for mine ball mill (MBMWT‐MCPMM). Based on the principle of removing coils, the stator is modularized. Each module can be regarded as a small rotary motor, which improves the reliability and fault tolerance of the motor. In this work, the structure and general design process of the MBMWT‐MCPMM are described, and the electromagnetic performance is simulated and analysed. The influence of different factors on the cooling effect of the motor and the temperature rise of different modules during fault‐tolerant operation are analysed. An 80 kW prototype is developed, and its experiments are carried out. The experimental results verify the validity of the related design and analysis.
Prüfungsthema: Müdigkeit
Authors: Schmid Eva C.
Published: October 2021

In diesem HPA-Prüfungstrainer beschäftigen sich alle Fragen mit Müdigkeit.
Aufbauen statt aufputschen!
Authors: Vigl Sebastian
Published: October 2021

Der Griff zu stimulierenden Substanzen wie Kaffee, Schwarztee & Co. bei Müdigkeit ist gängige Praxis, hilft nach Erfahrungen des Autors jedoch nur bei entsprechender energetischer Verfassung (siehe Tabelle 2). Die Nutzung von pflanzlichen Aufputschmitteln kann in einen schädlichen Gebrauch ausarten, wenn sie gewährleisten soll, dass Menschen über ihre gesunden Grenzen hinaus Leistung bringen. Aufgrund ihrer stimulierenden, stärkenden und entlastenden Wirkung sind Adaptogene Mittel der Wahl bei chronischer Erschöpfung und können je nach energetischer Verfassung mit anderen Pflanzen kombiniert werden.
Die Kaffeepflanze – ein Geschenk Afrikas an die Welt
Authors: Lorenz Daniel
Published: October 2021

Auf dem ganzen Globus bekannt und für viele unverzichtbarer Muntermacher – Kaffee. Doch die Kaffeepflanze hat einiges mehr zu bieten.
Überraschende Echobefunde als Erstdiagnose eines angeborenen Herzfehlers im Erwachsenenalter
Authors: Huntgeburth Michael , Hohmann Christopher , von Scheidt Fabian , Meierhofer Christian
Published: October 2021

Angeborene Herzfehler (AHF) werden teilweise erst im Erwachsenenalter diagnostiziert, entweder weil sie erst dann klinisch auffällig werden oder bei vorausgegangenen Untersuchungen übersehen wurden. Im Rahmen einer routinemäßigen transthorakalen Echokardiografie (TTE) können in der kardiologischen Praxis oder Klinik angeborene kardiale Anomalien leicht fehlgedeutet werden, da der Fokus in der Erwachsenenkardiologie überwiegend bei erworbenen Herzfehlern, einer Kardiomyopathie, Klappenerkrankungen oder einer systolischen oder diastolischen Dysfunktion liegt. Demgegenüber spielt eine thematische Auseinandersetzung mit AHF häufig eine nur untergeordnete Rolle, die Erwartungshaltung hinsichtlich angeborener kardialer Anomalien ist eher gering und die Sinne für mögliche AHF oft nicht geschärft. Dieser Artikel soll dazu beitragen, die Wahrscheinlichkeit des Erkennens eines AHF im Rahmen der TTE-Untersuchung zu erhöhen.
Frühe Diagnose und Therapie von Großgefäßvaskulitiden
Authors: Zeisbrich Markus , Venhoff Nils
Published: October 2021

Großgefäßvaskulitiden führen zu einer Entzündung großer und mittelgroßer Arterien. Zu ihnen zählen die Riesenzellarteriitis (RZA) und die Takayasu-Arteriitis (TAK). An der RZA erkranken vorwiegend ältere Menschen in der 7. und 8. Lebensdekade, während die TAK überwiegend junge Frauen im Alter zwischen 20 und 40 Jahren betrifft. Die RZA stellt die häufigste Vaskulitisform der westlichen Welt dar; die TAK tritt hingegen deutlich seltener im europäischen Raum auf. Die Entzündung der Gefäßwände führt zu ischämischen Komplikationen, wobei bei der RZA häufiger die Kopfarterien inklusive Augenarterien betroffen sind. Es besteht dann die Gefahr einer akuten Erblindung, die nur durch eine frühzeitige Diagnose und Therapieeinleitung verhindert werden kann. Beide Vaskulitisformen sind zudem durch eine ausgeprägte Entzündungskonstellation in Verbindung mit Fieber, Abgeschlagenheit und Gewichtsverlust gekennzeichnet. Zur Diagnosesicherung kommen bildgebende und histopathologische Verfahren zum Einsatz, wobei sich zur frühen Diagnostik einer RZA vor allem die Sonografie bewährt hat. Glukokortikoide stellen die Basis der medikamentösen Therapie dar und werden bei der RZA zunehmend häufig und bei der TAK regelmäßig um weitere Immunsuppressiva ergänzt.
Kawasaki-Syndrom
Authors: Neudorf Ulrich , Jakob André , Hospach Toni
Published: October 2021

Das Kawasaki-Syndrom ist eine inflammatorische Systemerkrankung unklarer Ätiologie und wird den Vaskulitiden zugeordnet. Es betrifft überwiegend Kinder unter 5 Jahren. Die Diagnose wird klinisch gestellt. Die seit 2004 existierende und zuletzt 2014 überarbeitete S1-Leitlinie der Gesellschaft für Kinder- und Jugendrheumatologie (GKJR) sollte mit Beteiligung der Deutschen Gesellschaft für pädiatrische Kardiologie und angeborene Herzfehler (DGPK) und Einschluss der Deutsche Gesellschaft für Kinder- und Jugendmedizin (DGKJ) überarbeitet werden. Dies ist in den Jahren 2018 und 2019 erfolgt 1. Die wesentlichen Neuerungen betreffen die Definition von Risikogruppen, die Einordnung der Therapieformen (Steroide, Biologika) und die Spezifizierung der Anforderungen an die Echokardiografie. Die Empfehlungen zum Langzeit-Follow-up wurden konkretisiert. Im laufenden Prozess der Feinabstimmung der Leitlinie wurde das Interesse an der Kawasaki-Erkrankung durch die Berichte von Kawasaki-ähnlichen Krankheiten im Rahmen von COVID-19-Infektionen dramatisch hoch. Damit hat sich eine neue Krankheit – Pediatric Inflammatory Multisystemic Syndrome (PIMS) oder Multisystem Inflammatory Syndrome in Children (MIS-C) – zur Differenzialdiagnose entwickelt.
Covalently Templated Syntheses of Mechanically Interlocked Molecules
Authors: van Maarseveen Jan H. , Cornelissen Milo D. , Pilon Simone
Published: October 2021

Mechanically interlocked molecules (MiMs), such as catenanes and rotaxanes, exhibit unique properties due to the mechanical bond which unites their components. The translational and rotational freedom present in these compounds may be harnessed to create stimuli-responsive MiMs, which find potential application as artificial molecular machines. Mechanically interlocked structures such as lasso peptides have also been found in nature, making MiMs promising albeit elusive targets for drug discovery. Although the first syntheses of MiMs were based on covalent strategies, approaches based on non-covalent interactions rose to prominence thereafter and have remained dominant. Non-covalent strategies are generally short and efficient, but do require particular structural motifs which are difficult to alter. In a covalent approach, MiMs can be more easily modified while the components may have increased rotational and translational freedom. Both approaches have complementary merits and combining the unmatched efficiency of non-covalent approaches with the scope of covalent syntheses may open up vast opportunities. In this review, recent covalently templated syntheses of MiMs are discussed to show their complementarity and anticipate future developments in this field.

1 Introduction

2 Tetrahedral Templates

2.1 A Carbonate Template for Non-Rusty Catenanes

2.2 All-Benzene Catenanes on a Silicon Template

2.3 Backfolding from Quaternary Carbon

3 Planar Templates

3.1 Rotaxanes Constructed in a Ring

3.2 Hydrindacene as a Dynamic Covalent Template

3.3 Templating on Tri- and Tetrasubstituted Benzenes

4 Conclusion
Intermolecular Nucleophilic Addition Reaction of a C-7 Anion from N-[Bis(dimethylamino)phosphoryl]indole to Electrophiles/Arynes: Synthesis of 7-Substituted Indoles
Authors: Singh Kamal Nain , Sharma Esha , Kaur Manjot , Kaur Babaldeep , Kaur Amarjit , Singh Paramjit
Published: October 2021

A novel approach to the C-7 substitution of N-[bis(dimethylamino)phosphoryl]indole by nucleophilic addition of the corresponding C-7 carbanion to electrophiles or arynes is described. The directing group can be easily removed, providing a simple route to the synthesis of 7-functionalized indoles.
Early Readmission following NICU Discharges among a National Sample: Associated Factors and Spending
Authors: Bernardo Janine , Keiser Amaris , Aucott Susan , Yanek Lisa R. , Johnson Clark T. , Donohue Pamela
Published: October 2021

Objective Infants admitted to the neonatal intensive care unit (NICU) are at increased likelihood of hospital readmission when compared with non-NICU admitted infants, resulting in appreciable financial and emotional burdens. Early readmission, days to weeks, following NICU discharge, may be preventable. Population-based data identifying potentially modifiable factors and spending associated with early readmission are lacking.

Study Design We conducted a secondary data analysis of privately insured infants in the IBM MarketScan Research Database born from 2011 to 2017 in all 50 states and admitted to the NICU. We examined demographic and clinical characteristics of early readmission within 7 days and between 8 and 30 days following NICU discharge and the payments of NICU and readmission care. Data were analyzed using univariate and multivariable logistic regression.

Results Of the 86,741 NICU survivors analyzed, 3,131 infants (3.6%) were readmitted by 7 days and 2,128 infants (2.5%) between 8 and 30 days. Preterm infants had reduced odds of readmission by 7 days compared with term infants. Infants transferred to a step-down facility (vs. discharge home) and those with congenital anomalies had higher independent odds of readmission by 7 and 8 to 30 days. A higher percentage of NICU infants within the lowest quartile of initial NICU length of stay (LOS) were readmitted by 7 days compared with NICU infants in the middle and highest LOS quartiles (64 vs. 36%, p < 0.01). Median payments of readmissions at 7 and 8 to 30 days was $12,785 and 14,380, respectively.

Conclusion Being term, being transferred to a step-down facility, and having a congenital anomaly were risk factors for early readmission. Shorter initial NICU LOS may be a contributing factor to readmission by 7 days, especially among term infants. These findings identify factors associated with readmission with the hope of preventing early readmission, minimizing spending, and optimizing ideal timing of NICU discharge.

Key Points
Handwashing Results in Incomplete Nicotine Removal from Fingers of Individuals who Smoke: A Randomized Controlled Experiment
Authors: Northrup Thomas F. , Stotts Angela L. , Suchting Robert , Khan Amir M. , Klawans Michelle R. , Green Charles , Hoh Eunha , Hovell Melbourne F. , Matt Georg E. , Quintana Penelope J. E.
Published: October 2021

Objective Tobacco residue, also known as third-hand smoke (THS), contains toxicants and lingers in dust and on surfaces and clothes. THS also remains on hands of individuals who smoke, with potential transfer to infants during visitation while infants are hospitalized in neonatal intensive care units (NICUs), raising concerns (e.g., hindered respiratory development) for vulnerable infants. Previously unexplored, this study tested handwashing (HW) and sanitization efficacy for finger-nicotine removal in a sample of adults who smoked and were visiting infants in an NICU.

Study Design A cross-sectional sample was recruited to complete an interview, carbon monoxide breath samples, and three nicotine wipes of separate fingers (thumb, index, and middle). Eligible participants (n = 14) reported current smoking (verified with breath samples) and were randomly assigned to 30 seconds of HW (n = 7) or alcohol-based sanitization (n = 7), with the order of finger wipes both counterbalanced and randomly assigned. After randomization, the first finger was wiped for nicotine. Participants then washed or sanitized their hands and finger two was wiped 5 minutes later. An interview assessing tobacco/nicotine use and exposure was then administered, followed by a second breath sample and the final finger wipe (40–60 minutes after washing/sanitizing).

Results Generalized linear mixed models found that HW was more effective than sanitizer for nicotine removal but failed to completely remove nicotine.

Conclusions Without proper protections (e.g., wearing gloves and gowns), NICU visitors who smoke may inadvertently expose infants to THS. Research on cleaning protocols are needed to protect vulnerable medical populations from THS and associated risks.

Key Points
Female Hyperandrogenism in Elite Sports and the Athletic Triad
Authors: Hirschberg Angelica Lindén
Published: October 2021

Essential hyperandrogenism seems to be overrepresented in female elite athletes. This applies to mild forms such as polycystic ovary syndrome, as well as rare differences/disorders of sex development (DSD). The reason is likely a selection bias since there is increasing evidence that androgens are beneficial for athletic performance by potent anabolic effects on muscle mass and bone mass, and stimulation of erythropoiesis. XY DSD may cause a greatly increased production of testosterone in the male range, that is, 10 to 20 times higher than the normal female range. The established regulations concerning the eligibility of female athletes with severe hyperandrogenism to compete in the female classification remain controversial. The most common cause of menstrual disorders in female athletes, however, is probably an acquired functional hypothalamic disturbance due to energy deficiency in relation to energy expenditure, which could lead to low bone mineral density and increased risk of injury. This condition is particularly common in endurance and esthetic sports, where a lean body composition is considered an advantage for physical performance. It is important to carefully evaluate endocrine disturbances and menstrual disorders in athletes since the management should be specific according to the underlying cause.
Characterization of a double torsion pendulum used to detect spin-induced torque based on Beth’s experiment
Authors: Yasuda Runa , Hatakeyama Atsushi
Published: October 2021

We characterized a double torsion pendulum system, including measurements of the photon-spin-induced torque. Our experimental strategy was similar to that used in Beth’s experiment, which was performed in 1936 to measure photon-spin-induced torque using forced oscillation caused by polarization modulation of light incident on a suspended object. Through simple passive isolation of the suspended object from external vibration noise, the achieved torque sensitivity was 2 × 10−17 N m in a measurement time of 104 s, which is close to the thermal noise limit and one order smaller than the minimum torque measured in Beth’s experiment. The observed spin-induced torque exerted on the light-absorbing optics is consistent with the angular momentum transfer of ℏ per photon.
A perspective on flexible sensors in developing diagnostic devices
Authors: Wang Lili , Jiang Kai , Shen Guozhen
Published: October 2021

The rapid development of flexible electronics, human–computer interaction, wireless technology, the Internet of Things, and internet health is promoting fast-past innovation in the field of wearable medical devices. Wearable devices are a category of personalized devices that include specialized sensors, which can make conformal contact with the human body or tissue to collect biochemical or electrophysiological signals. Hence, the development of high-precision flexible devices is attracting increasing interest as they can provide real-time medical data for monitoring the physiological state of patients and their diagnosis and treatment, as well as help individuals to pursue a healthier lifestyle. This Perspective reviews the developments and requirements of wearable flexible electronic devices in medical monitoring and then discusses the possible applications and challenges of using flexible sensor technology for point-of-care devices. Finally, an up-to-date discussion of the flexible sensor, its future prospects, and solutions it could provide in medical and diagnostic equipment are summarized.
Dynamic electrical conductivity induced by isothermal crystallization in aluminum hydroxide filled silicone rubber
Authors: Lin Ying , Liu Yuhao , Wu Kangning , Wang Liming , Ding Lijian
Published: October 2021

In this paper, taking aluminum hydroxide (ATH) filled silicone rubber as a model composite, we report the “n-shape” dynamic electrical conductivity during isothermal crystallization in nonconductive particles filled insulating polymers. During the initial crystallization, rapid growth of dominant lamellae blocks the transport path of impurity ions, contributing to the remarkable reduction of conductivity. Addition of ATH fillers could reduce the silicone rubber content and randomness of crystals formation, lessening the amplitude of decreased conductivity. Afterward, the silicone rubber composites further shrink due to the development of subsidiary lamellae. It results in low activation energy of ion migration and thereby enhances conductivity, whose amplitude is positively related to the crystalline phase. Finally, continuous growth of rigid amorphous fraction with reduced chain mobility impedes the ions transport, decreasing the conductivity again. The growth of rigid amorphous fraction is accelerated in silicone rubber with more ATH fillers because of more constraint of ATH on molecular chains. Our findings afford a simple means to manipulate insulation performance of nonconductive particles filled semi-crystalline polymers and provide a guideline for their use in real operation.
Improving interfacial charge transfer by multi-functional additive for high-performance carbon-based perovskite solar cells
Authors: Zou Yu , Yu Wenjin , Tang Zhenyu , Li Xiangdong , Guo Haoqing , Liu Ganghong , Zhang Qiaohui , Zhang Yuqing , Zhang Zehao , Wu Cuncun , Xiao Jing , Qu Bo , Chen Zhijian , Xiao Lixin
Published: October 2021

For perovskite solar cells with carbon electrodes (CPSCs) prepared using undoped hole transport materials and commercial carbon pastes, the poor interfacial carrier transport performance hinders the efficiency improvement. Herein, the use of additive 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) not only plays the role of passivating defects and assisting film formation but also regulates one to obtain more favorable interfacial energy band bending and energy level matching, while forming charge transfer complexes with perovskites due to its strong electron-withdrawing ability. Having all these functions at the same time makes CPSCs with F4TCNQ addition obtain high quality, low defect density films with suppressed non-radiative recombination, along with extremely fast carrier separation and extraction capabilities. Together with the optimization of the electron transport layer, the prepared CPSCs obtained an enhanced photovoltaic conversion efficiency of 15.1% and a VOC of 1.07 V with long stability.
Fabrication of InGaN/Si (111) nanowire heterostructure photoanode for hydrogen generation under visible light
Authors: Ravi Loganathan , Chauhan Prerna , Boopathi Kuppulingam
Published: October 2021

Group III-nitride alloys are believed to be promising photoelectrodes for photoelectrochemical water splitting to get hydrogen fuel. Here, we grew the InGaN nanowires (NWs) on silicon (111) as a photoanode using a low-cost chemical vapor deposition method. The photocurrent of an InGaN NWs' photoanode is five times greater than that of a GaN NWs' photoanode. The maximum photocurrent density of 8 mA/cm2 at 0.5 V vs the reverse hydrogen electrode with an applied bias photon-to-current efficiency of 5.8% was observed in the In30Ga70N NWs/Si (111) heterostructure. The incident photon-to-current conversion efficiency of 19.1% at 520 nm was observed for In30Ga70N NWs' photoanodes, which is much higher than GaN NWs. The hydrogen generation rates are 42.3 μmol/cm2 h at 0.15 V under 100 mW/cm2 white light irradiation. This InGaN/Si heterostructure photoanode improves photoelectrochemical performance for hydrogen fuel generation, paving the path for future development at a lower cost and on a larger scale.
Enhancing circular polarization of photoluminescence of two-dimensional Ruddlesden–Popper perovskites by constructing van der Waals heterostructures
Authors: Huang Lanyu , Zhang Danliang , Ge Cuihuan , He Mai , Zeng Zhouxiaosong , Wang Yufan , Liu Siman , Wang Xiao , Pan Anlian
Published: October 2021

Two-dimensions Ruddlesden–Popper perovskites (RPPs) are promising materials for spintronic devices due to the spin–orbit coupling. However, a relative low spin related photoluminescence (PL) circular polarization is observed from RPPs at room temperature due to the spin relaxation and spin flip caused by the soft lattice of RPPs. Here, we report the enhancement of the circular polarization of PL of RPPs by reducing the carrier lifetime of RPPs via constructing van der Waals heterostructures. We observed the maximum PL polarization of RPPs reaching about 30%. Moreover, we found that the degree of the polarization decreases as the thickness of the heterostructure becomes thicker. Our work provides an effective method to enhance the spin polarization of RPPs and could promote the RPPs based spintronics.
Control of concerted back-to-back double ionization dynamics in helium
Authors: Larsson Henrik R. , Tannor David J.
Published: October 2021

Double ionization (DI) is a fundamental process that despite its apparent simplicity provides rich opportunities for probing and controlling the electronic motion. Even for the simplest multielectron atom, helium, new DI mechanisms are still being found. To first order in the field strength, a strong external field doubly ionizes the electrons in helium such that they are ejected into the same direction (front-to-back motion). The ejection into opposite directions (back-to-back motion) cannot be described to first order, making it a challenging target for control. Here, we address this challenge and optimize the field with the objective of back-to-back double ionization using a (1 + 1)-dimensional model. The optimization is performed using four different control procedures: (1) short-time control, (2) derivative-free optimization of basis expansions of the field, (3) the Krotov method, and (4) control of the classical equations of motion. All four procedures lead to fields with dominant back-to-back motion. All the fields obtained exploit essentially the same two-step mechanism leading to back-to-back motion: first, the electrons are displaced by the field into the same direction. Second, after the field turns off, the nuclear attraction and the electron–electron repulsion combine to generate the final motion into opposite directions for each electron. By performing quasi-classical calculations, we confirm that this mechanism is essentially classical.
Bloch waves and non-commutative tori of magnetic translations
Authors: Dereli Tekin , Popov Todor
Published: October 2021

We review the Landau problem of an electron in a constant uniform magnetic field. The magnetic translations are the invariant transformations of the free Hamiltonian. A Kähler polarization of the plane has been used for the geometric quantization. Under the assumption of quasi-periodicity of the wavefunction, the Zak’s magnetic translations in the Bravais lattice generate a non-commutative quantum torus. We concentrate on the case when the magnetic flux density is a rational number. The Bloch wavefunctions form a finite-dimensional module of the noncommutative torus of magnetic translations as well as of its commutant, which is the non-commutative torus of magnetic translations in the dual Bravais lattice. The bi-module structure of the Bloch waves is shown to be the connecting link between two Morita equivalent non-commutative tori. The main focus of our review is the Kähler structure on the Hilbert space of Bloch waves and its inherent quantum toric geometry. We reveal that the metaplectic group Mp(2,R) of the automorphisms of magnetic translation algebras is represented by the quantum optics squeezing operators.
Optical flow method for neutron radiography flow diagnostics
Authors: Liu Tianshu , Zboray Robert , Trtik Pavel , Wang Lian-Ping
Published: October 2021

The principle of an optical flow method is formulated for neutron radiography (NR) flow diagnostics to determine high-resolution velocity fields of two-phase flows. This method is based on solving an optical flow equation derived from the continuous equation for NR image analysis as an inverse problem using a variational method. The mathematical definition and physical meaning of the optical flow in NR images of a two-phase flow are clarified. As an example, the optical flow method is used to extract complex velocity fields from a time sequence of dynamic NR images acquired in an air–water two-phase flow in a flat bubbler.
Flow map of foil undergoing combined fast and slow pitching
Authors: Chao Li-Ming , Alam Md. Mahbub , Ji Chunning , Wang Hanfeng
Published: October 2021

The drag-thrust transition and wake structures of a pitching foil undergoing combinations of fast and slow pitching are systematically investigated. The foil locomotion having combinations of fast and slow pitching is made by setting a variable s defined as the fraction of the pitching time required on the upper side of the wake centerline. On the other hand, time 1-s is required for the foil to pitch on the lower side of the wake centerline. Compared to the symmetric pitching (s = 0.5) case, the time-mean thrust rapidly increases and the drag-thrust boundary advances with increasing |s − 0.5|. The Kármán vortex street slants and produces thrust when |s − 0.5| is sufficiently large, which supersedes the previous thumb rule that only reverse Kármán vortex street can produce thrust. The faster forward stroke determines the slant direction of the vortex street. The detailed wake structures produced by the pitching foil are discussed, showing how the combined pitching affects vortex dynamics, drag-thrust transition, slant direction, and wake jet. This work provides a physical basis for understanding the hydrodynamics of native swimmers which may be useful to design bio-inspired underwater robots.
Sub-50 nm wavelength spin waves excited by low-damping Co25Fe75 nanowires
Authors: Wang Hanchen , Flacke Luis , Wei Weiwei , Liu Song , Jia Hao , Chen Jilei , Sheng Lutong , Zhang Jianyu , Zhao Mingkun , Guo Chenyang , Fang Chi , Han Xiufeng , Yu Dapeng , Althammer Matthias , Weiler Mathias , Yu Haiming
Published: October 2021

Spin waves are considered as a promising candidate for next-generation logic devices with low power dissipation. Exchange spin waves are particularly attractive for high-speed data processing and scaling down the size of magnonic logic devices. Here, we achieve the excitation of short-wavelength propagating spin waves with wavelengths as short as 45 nm in a 20 nm-thick yttrium iron garnet film covered by 70 nm-wide Co25Fe75 nanowires with low magnetic damping and high saturation magnetization, and the ferromagnetic resonance of Co25Fe75 nanowires is excited by a 200 nm-wide nano-strip line. From our measurements, we extrapolate a group velocity for exchange spin waves of up to 1.9 km/s close to the zero magnetic field (0.5 mT).
Proximity-induced magnetism and the enhancement of damping in ferromagnetic/heavy metal systems
Authors: Swindells C. , Głowiński H. , Choi Y. , Haskel D. , Michałowski P. P. , Hase T. , Kuświk P. , Atkinson D.
Published: October 2021

The relationship between proximity-induced magnetism (PIM) at the heavy metal/ferromagnet interface and spin-transport across such interfaces has generated significant debate. To investigate the link between the two, element specific x-ray magnetic circular dichroism and ferromagnetic resonance measurements were made on the same CoFe/Au/Pt and NiFe/Au/Pt thin film samples with varying Au thickness, with complementary SIMS analysis, which shows evidence of Ni diffusion from NiFe into the Pt. An approximately linear relationship is observed between the magnitude of Pt PIM and magnitude of damping enhancement in both systems. The results demonstrate that electronic hybridization of the heavy metal and ferromagnet is required for a full understanding of damping enhancement and interfacial spin-transport for spintronic devices.
Simplified feedback control system for scanning tunneling microscopy
Authors: Martín-Vega Francisco , Barrena Víctor , Sánchez-Barquilla Raquel , Fernández-Lomana Marta , Benito Llorens José , Wu Beilun , Fente Antón , Perconte Duplain David , Horcas Ignacio , López Raquel , Blanco Javier , Higuera Juan Antonio , Mañas-Valero Samuel , Jo Na Hyun , Schmidt Juan , Canfield Paul C. , Rubio-Bollinger Gabino , Rodrigo José Gabriel , Herrera Edwin , Guillamón Isabel , Suderow Hermann
Published: October 2021

A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few Å. Often, the tunneling current between the tip and the sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here, we discuss another approach using a computer and data acquisition through the universal serial bus port. We find that it allows successful ultralow noise studies of surfaces at cryogenic temperatures. We show results on different compounds including a type II Weyl semimetal (WTe2), a quasi-two-dimensional dichalcogenide superconductor (2H–NbSe2), a magnetic Weyl semimetal (Co3Sn2S2), and an iron pnictide superconductor (FeSe).
Demonstration of a compact x-ray free-electron laser using the optical klystron effect
Authors: Prat Eduard , Ferrari Eugenio , Calvi Marco , Ganter Romain , Reiche Sven , Schmidt Thomas
Published: October 2021

We demonstrate the operation of a compact x-ray free-electron laser (FEL) using the optical klystron mechanism. This effect speeds up the FEL process using the dispersion of magnetic chicanes placed between the undulator modules of the FEL beamline. The demonstration was performed at the soft x-ray beamline of SwissFEL, called Athos, which is, as far as we are aware, the only x-ray FEL to date with magnetic chicanes between every two undulator modules. In our measurements, we show that, compared to standard operation without chicanes, the required undulator length to achieve FEL saturation is reduced between 15% and 30% for radiation wavelengths between 1 and 2 nm. Fully exploiting the optical klystron effect represents an important step toward more compact FEL designs, rendering this key technology more affordable and hence accessible to a larger science community.
Effect of geometrical design on the latent heat cooling properties of a lightweight two-phase composite
Authors: Seetoh Ian P. , Jovin Daniel , Lai Chang Quan
Published: October 2021

Latent heat storage materials undergo phase changes to maintain a constant temperature environment and are fast emerging as a passive “green” technology for thermal management. Phase-change materials (PCMs) typically have poor thermal conductivities; however, their response to rapid fluctuations in temperature can be sluggish. Here, we explore the feasibility of adding various aluminum alloy (AlSi10Mg) structures to speed up the thermal response. The cooling performance of various geometries with the same mass density was first investigated, and the best performing geometries were then further optimized to investigate the possible weight savings. Our results indicate that, for unidirectional heat flux, designs with 3D periodicity, such as triply periodic minimal surfaces, do not perform as well as those with 1D (parallel plates) and 2D (honeycombs) periodicity. Furthermore, a strong correlation was found between the cooling performance and the interfacial area density. An expanding melt front, which leads to an increase in the interfacial area for heat transfer over time, and even heat distribution were also observed to be advantageous. After optimization, the honeycomb design with tapered triangular rods surrounded by the PCM matrix was able to achieve greatest weight savings for a given performance requirement. Compared to a thermal management panel consisting solely of the PCM, it was able to keep a heated surface cooler by 90% and also outperformed a pure Al panel despite being more than 40% lighter.
Development of zinc oxide-multi-walled carbon nanotube hybrid nanofluid for energy-efficient heat transfer application: A thermal lens study
Authors: Gokul V. , Swapna M. S. , Raj Vimal , Gratowski Svetlana von , Sankararaman S.
Published: October 2021

This paper addresses the need for developing an energy-efficient hybrid nanofluid with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) for overcoming the bottleneck of efficient heat transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive mode mismatched thermal lens technique. The hybrid composite is prepared by the solid-state mixing and annealing of a pure multi-walled carbon nanotube (MWCNT) and zinc oxide (ZnO), synthesized by the solution combustion method. The composite formation is studied by structural, morphological, and optical characterization techniques. Among the three nanofluids ZnO, MWCNT, and ZnO-MWCNT, the composite exhibits a drastic enhancement in thermal diffusivity at a lower solid volume fraction of 0.047 mg/ml containing 0.009 mg/ml of MWCNT. All the nanofluids show an optimum concentration beyond which the thermal diffusivity decreases with the nanoparticle concentration. Thus, this study suggests the potential application of ZnO-MWCNT hybrid nanofluids in thermal system design to enhance internal combustion engines' efficiency during cold-start.
Drop-casting CsPbBr3 perovskite quantum dots as down-shifting layer enhancing the ultraviolet response of silicon avalanche photodiode
Authors: Liu T. , Liu X. , Chen D. , Liu Q. , Zuo Y. , Guo X. , Zheng J. , liu Z. , Xue C. , Cheng B.
Published: October 2021

Since the absorption zone of ultraviolet (UV) photons with high energy is limited to a few tens of nm on the surface, the high defect density caused by the processes, such as ion implantation, leads to a weak response of the silicon avalanche photodiode (APD) in the ultraviolet band. In this work, the integration of the inorganic perovskite quantum dots (QDs) film by drop-casting as the down-shifting layer is reported for enhancing the UV response of Si APD. The light generated current increases 100% under the 365 nm light emitting diode. The response of the Si APD is improved in the entire ultraviolet band. In particular, the responsivity of APD is increased by 78% at 340 nm with an exceedingly EQE of 92%. In summary, the perovskite QDs film as a down-shifting layer provides an effective and low-cost method to improve the UV response of Si APD.
Non-Newtonian laminar flow in pipes using radius, stress, shear rate or velocity as the independent variable
Authors: Tozzi E. , Hartt W.
Published: October 2021

The flow of a non-Newtonian fluid in a circular pipe is a classic introductory transport phenomena problem, familiar to readers of Robert Byron Bird textbooks. A characteristic of Bird's work was taking the time to explore alternative ways to describe a problem and refine the results into elegant and readable formulas. Inspired by that approach, we compare methods for pipe flow solutions that differ on the independent variable used (radius, stress, shear rate) to obtain flow rate and residence time distributions for generalized Newtonian fluids. We highlight cases where using the shear rate as the independent variable has advantages for analytical and numerical solutions. We describe a method to use velocimetry experimental data coupled with a pressure drop measurement to directly construct a curve of flow rate vs pressure drop without the need of fitting the data to any rheological models. We present a geometrical interpretation of velocity profiles as areas in the stress–shear rate plane and derive analytical solutions for a three-parameter model of soft glassy materials [Caggioni et al., “Variations of the Herschel–Bulkley exponent reflecting contributions of the viscous continuous phase to the shear rate-dependent stress of soft glassy materials,” J. Rheol. 64, 413 (2020)] and a four-parameter model for chocolate melts [H. D. Tscheuschner, “Rheologische eigenschaften von lebensmittelsystemen,” in Rheologie Der Lebensmittel, edited by D. Weipert, H. Tscheuschner, and E. Windhab (Behr's Verlag, Hamburg, 1993), pp. 101–172]. We also compare the speed of various numerical approaches for a fractional viscoelastic model [A. Jaishankar and G. H. McKinley, “A fractional K-BKZ constitutive formulation for describing the nonlinear rheology of multiscale complex fluids,” J. Rheol. 58, 1751 (2014)].
Predissociation measurements of the bond dissociation energies of EuO, TmO, and YbO
Authors: Merriles Dakota M. , Tomchak Kimberly H. , Ewigleben Joshua C. , Morse Michael D.
Published: October 2021

The observation of a sharp predissociation threshold in the resonant two-photon ionization spectra of EuO, TmO, and YbO has been used to measure the bond dissociation energies of these species. The resulting values, D0(EuO) = 4.922(3) eV, D0(TmO) = 5.242(6) eV, and D0(YbO) = 4.083(3) eV, are in good agreement with previous values but are much more precise. In addition, the ionization energy of TmO was measured by the observation of a threshold for one-color two-photon ionization of this species, resulting in IE(TmO) = 6.56(2) eV. The observation of a sharp predissociation threshold for EuO was initially surprising because the half-filled 4f7 subshell of Eu in its ground state generates fewer potential energy curves than in the other molecules we have studied by this method. The observation of a sharp predissociation threshold in YbO was even more surprising, given that the ground state of Yb is nondegenerate (4f146s2, 1Sg) and the lowest excited state of Yb is over 2 eV higher in energy. It is suggested that these molecules possess a high density of electronic states at the energy of the ground separated atom limit because ion-pair states drop below the ground limit, providing a sufficient electronic state density to allow predissociation to set in at the thermochemical threshold.
Determination of the SmO+ bond energy by threshold photodissociation of the cryogenically cooled ion
Authors: Lachowicz Anton , Perez Evan H. , Shuman Nicholas S. , Ard Shaun G. , Viggiano Albert A. , Armentrout P. B. , Goings Joshua J. , Sharma Prachi , Li Xiaosong , Johnson Mark A.
Published: October 2021

The SmO+ bond energy has been measured by monitoring the threshold for photodissociation of the cryogenically cooled ion. The action spectrum features a very sharp onset, indicating a bond energy of 5.596 ± 0.004 eV. This value, when combined with the literature value of the samarium ionization energy, indicates that the chemi-ionization reaction of atomic Sm with atomic oxygen is endothermic by 0.048 ± 0.004 eV, which has important implications on the reactivity of Sm atoms released into the upper atmosphere. The SmO+ ion was prepared by electrospray ionization followed by collisional breakup of two different precursors and characterized by the vibrational spectrum of the He-tagged ion. The UV photodissociation threshold is similar for the 10 K bare ion and the He tagged ion, which rules out the possible role of metastable electronically excited states. Reanalysis and remeasurement of previous reaction kinetics experiments that are dependent on D0(SmO+) are included, bringing all experimental results in accord.
All-nitrogen spiropentadiene—N5+
Authors: Tian Xiao , Bo Xiao-xu , Ding Yi-hong
Published: October 2021

Of the pentanitrogen cation (N5+) family, the only experimentally known isomer is the V-shaped structure 01. Here, we showed that a super-high-energy (∼100 kcal/mol above 01) all-nitrogen spiropentadiene 02 with considerable σ-delocalization deserves pursuit as the first spirocyclic all-nitrogen molecule, at least spectroscopical.
A perspective on the pathway toward full wave simulation of large area metalenses
Authors: Hughes Tyler W. , Minkov Momchil , Liu Victor , Yu Zongfu , Fan Shanhui
Published: October 2021

Metalenses for optical beam manipulation have a significant impact in many exciting applications due their compact, planar geometry and ease of fabrication. However, the enormous physical size of metalenses relative to the optical wavelength provides a barrier to performing accurate simulations in a reasonable time frame. In principle, full-wave simulation techniques, such as the finite-difference time-domain (FDTD) method, are ideal for metalens modeling as they give an accurate picture of the device performance. However, when applied using traditional computing platforms, this approach is infeasible for large-diameter metalenses and requires hours and days to simulate even devices of modest size. To alleviate these issues, the standard approach has been to apply approximations, which typically employ simplified models of the metalens unit cells or ignore coupling between cells, leading to inaccurate predictions. In this Perspective, first, we summarize the current state of the art approaches in simulating large scale, three-dimensional metalenses. Then, we highlight that advances in computing hardware have now created a scenario where the full-wave simulation of large area metalenses is feasible within a reasonable time frame, providing significant opportunities to the field. As a demonstration, we show that a hardware-accelerated FDTD solver is capable of simulating a fully 3D, large area metalens of size 100λ × 100λ, including the focal length, in under 5 min. The application of hardware-accelerated, full-wave simulation tools to metalens simulation should have a significant impact in the metalens field and the greater photonics community.
Selective promiscuity in the binding of
E. coli
Hsp70 to an unfolded protein
Authors: Clerico Eugenia M. , Pozhidaeva Alexandra K. , Jansen Rachel M. , Özden Can , Tilitsky Joseph M. , Gierasch Lila M.
Published: October 2021

Significance

The cellular functions of Hsp70 molecular chaperones rely on their ability to bind many clients and discriminate folded from unfolded substrates. We find that the
Escherichia coli
Hsp70 substrate binding domain (SBD) “reads” sequence motifs without regard for backbone orientation and selects binding modes that optimize residue compatibility with pockets in the SBD binding cleft. Multiple potential binding sites on the unfolded substrate interacted with the SBD independently in roughly the same order of apparent affinities observed for the peptide models of the sites. Our results show in detail how an Hsp70 chaperone binds to an unfolded protein substrate, which will inform efforts to predict Hsp70 binding sites and shed light on chaperone functions.