bluuebunny/crossref_metadata_2025 huggingface dataset:
Gesundheitshotline 1450: Potenziale in städtischen Gebieten
Niederösterreichs. Eine retrospektive Analyse.
Authors: Schullern Christoph , Nöhammer Elisabeth
Published: May 2023

Hintergrund Gesellschaftliche (Erwartungs-)Veränderungen,
Effizienzbestrebungen in den Gesundheitssystemen und zum Teil hoher
individueller Beratungsbedarf wegen geringer Gesundheitskompetenz stehen
einander gegenüber. Triagierende Gesundheitshotlines, die Anrufende an
best Points of Care (POC) weiterleiten, sind mögliche
Lösungsansätze. Ziel der Studie ist, die Potenziale der
österreichischen Gesundheitshotline 1450 hinsichtlich Vermittlung des
POC zu analysieren, um Muster und Verbesserungsmöglichkeiten zu
erkennen.

Methode Daten von 01.01.– 31.12.2019 von zwei städtischen
Gebieten Niederösterreichs mit deren Top fünf Systemdiagnosen
und fünf häufigsten POC pro Stadt werden retrospektiv analysiert
und verglichen. Pandemiebedingte Verzerrungen werden so verhindert.

Ergebnisse Die häufigsten fünf Anrufgründe
unterscheiden sich je nach Stadt, es ergeben sich damit sechs in der
Gesamtstichprobe (n=4376): Erbrechen (4,8%),
Rückenschmerzen (3,0%), Schwindelgefühl oder
Drehschwindel (2,5%), abdominelle Schmerzen (2,4%),
Brustschmerzen (1,5%) und Kopfschmerzen (1,4%). Der absolute
best POC ist der Rettungsdienst mit 38,7% (Rettungswagen Auftrag und
Einsatz). In Kombination mit der Empfehlung eine Notfallaufnahme (18,5%)
aufzusuchen ergibt sich ein hoher Anteil (57,2%) an durch den
Rettungsdienst und die Krankenhausstruktur zu Versorgenden. Die
häufigsten POC Zuweisungen decken in beiden Städten (Stadt A
89,8%/Stadt B 92,0%) in hohem Ausmaß die
verfügbaren Versorgungspunkte in städtischen Gebieten ab.

Schlussfolgerung Bei einzelnen Beschwerdebildern scheint eine umfassendere
Zuweisung in den niedergelassenen Bereich möglich (Kopfschmerzen,
Rückenschmerzen, abdominale Schmerzen). Da die fünf
häufigsten Anrufgründe nur 15,6% (n=682) aller
dokumentierten Beratungsgespräche der Gesamtstichprobe ausmachen, sind
weitere Untersuchungen nötig. Dringlichkeitseinstufung und
Anrufzeitpunkt sollten berücksichtigt werden.
Quantitatives EMG – müssen zwanzig Einheiten gemessen
werden oder genügen drei?
Authors: Schulte-Mattler Wilhelm J. , Bischoff Christian
Published: May 2023

Fritz Buchthals Beitrag zur Elektromyographie (EMG) ist fundamental. Als eines
der Fundamente der quantitativen EMG gilt aber auch, dass die Dauer der
Aktionspotenziale von 20 verschiedenen motorischen Einheiten zu messen sei, um
quantitativ EMG zu betreiben. Dieser Ansatz ist schon aus theoretischen
Erwägungen nicht sinnvoll, nicht nur des großen damit
verbundenen Aufwands wegen. Durch Messung nur weniger motorischer Einheiten, die
deutlich außerhalb der Norm liegen, der
„Ausreißer“, ist es hingegen häufig
möglich, ohne großen Zeitaufwand und zuverlässig
belastbare EMG-Befunde zu erheben.
Ferroptosis Signaling Pathways: Alzheimer's
Disease
Authors: Maheshwari Shubhrat
Published: May 2023

The involvements of iron metabolism, lipid peroxidation, and oxidative stress in
Alzheimer's disease (AD) development have recently received a lot of
attention. We also observe that these pathogenic occurrences play a key role in
regulating ferroptosis, a unique regulatory cell death that is iron-dependent,
oxidative, and non-apoptotic. Iron is a crucial component that makes up a
subunit of the oxidase responsible for lipid peroxidation. A family of non-heme
iron enzymes known as lipoxygenases (LOXs) can cause ferroptosis by oxidising
polyunsaturated fatty acids in cellular membranes (PUFAs). Toxic lipid
hydroperoxides are produced in large part by the iron in LOX active sites.
Deferoxamine and deferiprone, two iron chelators, could also treat ferroptosis
by eliminating the crucial catalytic iron from LOXs. Phospholipids containing
polyunsaturated fatty acids are the main substrates of lipid peroxidation in
ferroptosis, which is favourably controlled by enzymes like ACSL4, LPCAT3,
ALOXs, or POR. Selective stimulation of autophagic degradation pathways leads to
an increase in iron accumulation and lipid peroxidation, which promotes
ferroptosis. We highlighted recent advancements in our understanding of
ferroptosis signaling routes in this study. One form of regulated necrotic cell
death known as ferroptosis has been linked to a number of diseases, including
cancer, neurological disorders, and ischemia/reperfusion injury.
Cerebrospinal fluid (CSF) ferritin may be a good indicator of the amount of iron
in the brain because it is the main protein that stores iron.
The Total Synthesis of Mollanol A by a Convergent Strategy
Authors: Yang Ming
Published: May 2023

Here, we briefly highlight our 15-step total synthesis of mollanol A, the first isolated member of the mollane-type grayanoids, which relied on a convergent strategy. A Stille coupling and a vinylogous aldol reaction/intramolecular oxa-Michael addition sequence were used to assemble the two fragments that featured most of the important chiral centers and nearly all the essential oxidation states of the natural product. The bicyclo[3.2.1]octane fragment was synthesized by using an InCl3-catalyzed Conia–ene cyclization reaction. The challenging tetrasubstituted alkene was constructed through a 1,4-reduction of the conjugated alkenes at a late stage.

1 Introduction

2 Total Synthesis of Mollanol A

3 Conclusion
Effects of Intraventricular Vancomycin Administration on the Prevention of Ventricular Shunt Infection
Authors: hasanpour mohammad , rezaee hamid , Samini fARIBORZ , keykhosravi ehsan
Published: June 2023

Introduction and Objectives: Shunt infection causes death in many patients diagnosed with hydrocephalus and increases the duration of hospitalization and treatment costs. A high percentage of children are forced to undergo re-surgery due to shunt dysfunction or infection. The present study aimed to investigate the role of intraventricular (IVT) vancomycin in the prevention of ventricular shunt infection in children with hydrocephalus who were referred to Akbar Hospital in Mashhad, Iran, between the years 2017 and 2021.
Materials and Methods: The present descriptive cross-sectional study was conducted on 192 children with hydrocephalus who underwent shunt surgery at Akbar Hospital in Mashhad, Iran, between the years 2017 and 2021. Patients were divided into two groups of intervention (n=69) and control (n=123). The patients in the intervention group received 30 mg of IVT vancomycin during shunt surgery. The rate of shunt obstruction and infection were then compared between the two study groups.
Results: The two study groups were matched in terms of demographic and clinical information except for gender (P=0.02). Moreover, no significant difference was reported between the two groups in terms of intelligence development (χ2=0.51; P=0.47), verbal development (χ2=0.1; P=0.75), and movement development (χ2=1.05; P=0.3). The frequency of shunt infection and shunt obstruction was estimated at 8.8% and 18.2%, respectively. The shunt infection rate was lower in the vancomycin IVT group than in the control group (χ2=4.07; P=0.04), while no difference was observed between the two groups in terms of shunt obstruction (χ2=3.66; P=0.056). The comparison of the two study groups indicated no significant difference between them in terms of mortality (χ2=0.004; P=0.95).
Conclusion: It seems that IVT vancomycin should be recommended for inclusion in hydrocephalus surgery protocol to reduce postoperative shunt infection. It is recommended that shunt protocols be adopted in future multicenter prospective randomized controlled trials on the reduction of ventriculoperitoneal shunt infections to further evaluate the efficacy of IVT antibiotics
Low HDL Cholesterol is Associated with Reduced Bleeding Risk in Patients who Underwent PCI: Findings from the PRACTICE Study
Authors: Zheng Ying-Ying , Wu Ting-Ting , Hou Xian-Geng , Yang Yi , Yang Hai-Tao , Pan Ying , Xiu Wen-Juan , Ma Xiang , Ma Yi-Tong , Yang Xin-Ling , Xie Xiang
Published: June 2023

Background We sought to examine the dose–response relationship between high-density lipoprotein cholesterol (HDL-C) and bleeds in coronary artery disease (CAD) patients who underwent percutaneous coronary intervention (PCI).

Methods All the 15,250 participants were from the Personalized Antiplatelet Therapy According to CYP2C19 Genotype in Coronary Artery Disease (PRACTICE) study, which is a large, single-center, prospective cohort study based on case records and a follow-up registry performed in the First Affiliated Hospital of Xinjiang Medical University from December 2016 to October 2021. We divided all the patients into five groups according to their HDL-C levels: the ≤35 mg/dL group (n = 4,732), 35 to 45 mg/dL group (n = 6,049), 45 to 55 mg/dL group (n = 2,826), 55 and 65 mg/dL group (n = 1,117), and >65 mg/dL group (n = 526). The incidence of bleeds, mortality, ischemic events, and net adverse clinical events (NACEs) among the five groups was compared.

Results A total of 713 bleeds, 1,180 ischemic events, 456 deaths, and 1,893 NACEs were recorded during the up to 60-month follow-up period. After adjusting for confounders, we observed a nonlinear relation for bleeds, with the highest risk at intermediate HDL-C levels (45–55 mg/dL). We also identified a dose–response relationship for ischemic events. A threshold value of HDL-C ≤35 mg/dL (adjusted hazard ratio = 0.560, 95% confidence interval: 0.360–0.872, p = 0.010) was associated with a decreased risk for bleeds in the multivariable Cox regression model. The results were consistent in multiple sensitivity analyses and propensity score-matching analysis.

Conclusion In the present study, a nonlinear association was identified between HDL-C levels and bleeds in CAD patients who underwent PCI, with a higher risk at intermediate levels. However, further multicenter studies are warranted.
Rhinal and hippocampal event-related potentials as epileptogenic zone markers in the pre-surgical evaluation of temporal epilepsies: a systematic review
Authors: Morange Daniela de Andrade , Amaral Magali Teresópolis Reis , Martinez-Silveira Martha Silvia , Trébuchon Agnès
Published: May 2023

Background Cognitive event-related potentials (ERPs) allow for lateralization of the epileptogenic zone (EZ) to estimate the reserve of memory in the contralateral non-epileptogenic hemisphere, and to investigate the prognosis of temporal lobe seizure control in unilateral temporal lobe epilepsy (TLE).

Objective To define the accuracy of cognitive evoked anterior mesial temporal lobe (AMTL-N400) and P600 potentials in detecting the epileptogenic zone in temporal lobe epilepsy (TLE), and second, to evaluate the possibility of using them as markers of cognitive outcome.

Methods The systematic review using Medline/PubMed, Embase, and Lilacs database was conducted in September 2021. Only articles published in English from 1985 to June 2021 were included. We searched for studies with: (1) depth intracranial electroencephalography (iEEG) recordings analysis of rhinal and hippocampal activity (2) correlations between ERP results obtained in the mesial temporal regions (AMTL-N400 and P600) and the epileptogenic zone.

Results Six out of the seven studies included in this review defined the laterality of the epileptogenic zone (EZ) during presurgical investigation using ERPs. One study showed that the contralateral AMTL-N400 predicts seizure control. Another study found correlation between the amplitudes of the right AMTL-N400 and postoperative memory performance.

Conclusions There is evidence that the reduced amplitude of the AMTL-N400 has high accuracy in identifying the epileptogenic zone, as it does in estimating the extent of seizure control and memory impairment in postoperative patients.
Brain glucose metabolism and gray matter volume in retired professional soccer players: a cross-sectional [18F]FDG-PET/MRI study
Authors: Aranha Mateus Rozalem , Coutinho Artur Martins , Carneiro Camila de Godoi , Pastorello Bruno Fraccini , Studart-Neto Adalberto , Guariglia Carla Cristina , Tsunemi Miriam Harumi , Moreira Everton Luis Santos , Ianof Jéssica Natuline , Anghinah Renato , Nitrini Ricardo , Cerri Giovanni Guido , Fortea Juan , Buchpiguel Carlos Alberto , Leite Claudia Costa
Published: May 2023

Background Professional soccer athletes are exposed to repetitive head impacts and are at risk of developing chronic traumatic encephalopathy.

Objective To evaluate regional brain glucose metabolism (rBGM) and gray matter (GM) volume in retired soccer players (RSPs).

Methods Male RSPs and age and sex-matched controls prospectively enrolled between 2017 and 2019 underwent neurological and neuropsychological evaluations, brain MRI and [18F]FDG-PET in a 3.0-Tesla PET/MRI scanner. Visual analysis was performed by a blinded neuroradiologist and a blinded nuclear physician. Regional brain glucose metabolism and GM volume were assessed using SPM8 software. Groups were compared using appropriate statistical tests available at SPM8 and R.

Results Nineteen RSPs (median [IQR]: 62 [50–64.5] years old) and 20 controls (60 [48–73] years old) were included. Retired soccer players performed worse on mini-mental state examination, digit span, clock drawing, phonemic and semantic verbal fluency tests, and had reduced rBGM in the left temporal pole (pFDR = 0.008) and the anterior left middle temporal gyrus (pFDR = 0.043). Semantic verbal fluency correlated with rBGM in the right hippocampus, left temporal pole, and posterior left middle temporal gyrus (p ≤ 0.042). Gray matter volume reduction was observed in similar anatomic regions but was less extensive and did not survive correction for multiple comparisons (pFDR ≥ 0.085). Individual [18F]FDG-PET visual analysis revealed seven RSPs with overt hypometabolism in the medial and lateral temporal lobes, frontal lobes, and temporoparietal regions. Retired soccer players had a higher prevalence of septum pellucidum abnormalities on MRI.

Conclusion Retired soccer players had reduced rBGM and GM volume in the temporal lobes and septum pellucidum abnormalities, findings possibly related to repetitive head impacts.
Factors Influencing Outcome of Orbital Floor Reconstruction
Authors: Varghese Sony Prakkattumannathu , Victor Jonathan , Ramdas Sharad , Lingam P.P. , Prasanth Hannah Ranjee , Jaganathan Vijay , Kumar Dinesh
Published: June 2023

Introduction Orbital floor fractures are routinely encountered in facial trauma. Many factors influence the final outcome of the orbital floor surgery, time interval and the extent of other facial bone fractures are the two factors which can significantly influence the postoperative outcome following orbital floor reconstruction. Our study aims to find the ideal time for intervention and the association of other factors in the final outcome of orbital floor reconstruction.

Methods A retrospective and prospective cohort study of patients who were operated at Pondicherry Institute of Medical Sciences for orbital floor fractures, between 2011 January and 2017 July. All the data were entered on an Excel work sheet and statistically analyzed.

Results In our study 8 patients (8/29, 27.58%) had diplopia prior to surgery, 5 patients (5/29, 17.24%) had complete recovery following surgery and 3 patients (3/29, 10.34%) had persistence of diplopia postoperatively. Patients with diplopia operated prior to 7 days were found to have significant improvement in postoperative diplopia. Patients with 5 or more facial fractures were found to have persistence of diplopia, infraorbital numbness, and enophthalmos postoperatively.

Conclusion Our study suggests that early intervention, before 7 days improves the outcome in patients with diplopia and provides a better result postoperatively. In our study preoperative diplopia and infraorbital numbness and postoperative persistence of enophthalmos, diplopia, and paresthesia were found more in patients with 5 or more facial bone fractures. Our study suggests a poor postoperative outcome when 5 or more facial bones are fractured.
Effect of Maternal Coronavirus Disease on Preterm Morbidities
Authors: Çıplak Gökçe , Becerir Cem , Sarı Fatma N. , Alyamaç Dizdar Evrim
Published: May 2023

Objective Coronavirus disease (COVID-19) during pregnancy may have an impact on preterm morbidities due to the inflammatory nature of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Exposure to intrauterine inflammation could result in adverse consequences in preterm infants. We aimed to determine the effect of maternal coronavirus disease on preterm morbidities at a tertiary neonatal intensive care unit.

Study Design This observational cohort study compared the clinical outcomes of preterm infants < 37 gestational weeks with and without maternal COVID-19. The study was conducted in a tertiary-level neonatal intensive care unit between March 2020 and December 2021. Demographics and clinical data of the study groups were collected from the medical files.

Results A total of 254 infants (127 in the maternal COVID-19 group and 127 in the control group) were included in the study. Respiratory distress syndrome, early and late neonatal sepsis, intraventricular hemorrhage, patent ductus arteriosus (PDA), necrotizing enterocolitis, bronchopulmonary dysplasia, and retinopathy of prematurity rates were similar between groups. In the subgroup analysis, the rate of PDA was significantly higher in preterm infants ≤1,500 g with maternal SARS-CoV-2 infection (38 vs. 15% p = 0.023). Presence of maternal COVID-19 was found to be an independent predictor for PDA in very low birthweight infants, as revealed by multivariate analyses (odds ratio: 3.4; 95% confidence interval: 1.12–10.4; p = 0.031). Mortality rates and duration of hospitalization were similar in both groups.

Conclusion Our results suggest that COVID-19 infection during pregnancy seems to have no adverse effect on preterm morbidities and mortality. However, maternal COVID-19 was found to be a risk factor for PDA in preterm infants ≤1,500 g.

Key Points
In situ and operando study of catalysts during high-temperature high-pressure catalysis in a fixed-bed plug flow reactor with x-ray absorption spectroscopy
Authors: Tang Yu , Nguyen Luan , Li Yuting , Tao Franklin
Published: May 2023

Numerous important catalytic reactions, such as Fischer–Tropsch synthesis (FTS), are performed under harsh conditions in terms of high temperature of a catalyst in a mixture of reactants at a high pressure. There has been a lack of an intrinsic correlation between a catalytic performance and its corresponding catalyst structure due to the unavailable information on the authentic structure of the catalyst during catalysis under a high-temperature high-pressure (HTHP) condition. Here, we report in situ/operando studies of Co catalysts during catalysis under HTHP conditions using x-ray absorption spectroscopy (XAS). A high-temperature high-pressure catalysis-XAS (HTHP Catalysis-XAS) system using a thin, small quartz or beryllium tube as the reactor was built for in situ/operando characterization of high-energy absorption edges of 4d transition metals or low-energy absorption edges of 3d/4d transition metals under high-temperature high-pressure conditions, respectively. This reactor can be used for HTHP catalysis performed at a temperature of up to 550 °C and a gas pressure of up to 60 bars for uncovering the chemical states and coordination environments of metal atoms of these catalysts during HTHP catalysis. The capability of collecting XAS data during HTHP catalysis was confirmed through tests at 400oC in the mixture of 20 bar mixture of reactants at beamline endstation. The operando studies of Ru catalyst particles under Fischer–Tropsch catalytic conditions with extended x-ray absorption fine structure spectroscopy revealed a restructuring of the Ru catalyst at 250 °C in the mixture of 6 bars CO and 12 bars H2 during FTS (30 ml/min), which was not observed at 300 °C in 1 bar H2 (20 ml/min). This observation suggests new chemistry for metal catalysts under HTHP condition inaccessible due to a lack of applicable characterizations. These tests confirmed the function of this HTHP Catalysis-XAS system for in situ/operando characterizations of catalysts during HTHP catalysis.
Review of nanomaterial advances for ionizing radiation dosimetry
Authors: Aboelezz Eslam , Pogue Brian W.
Published: May 2023

There are a wide range of applications with ionizing radiation and a common theme throughout these is that accurate dosimetry is usually required, although many newer demands are provided by improved features in higher range, multi-spectral and particle type detected. Today, the array of dosimeters includes both offline and online tools, such as gel dosimeters, thermoluminescence (TL), scintillators, optically stimulated luminescence (OSL), radiochromic polymeric films, gels, ionization chambers, colorimetry, and electron spin resonance (ESR) measurement systems. Several future nanocomposite features and interpretation of their substantial behaviors are discussed that can lead to improvements in specific features, such as (1) lower sensitivity range, (2) less saturation at high range, (3) overall increased dynamic range, (4) superior linearity, (5) linear energy transfer and energy independence, (6) lower cost, (7) higher ease of use, and (8) improved tissue equivalence. Nanophase versions of TL and ESR dosimeters and scintillators each have potential for higher range of linearity, sometimes due to superior charge transfer to the trapping center. Both OSL and ESR detection of nanomaterials can have increased dose sensitivity because of their higher readout sensitivity with nanoscale sensing. New nanocrystalline scintillators, such as perovskite, have fundamentally important advantages in sensitivity and purposeful design for key new applications. Nanoparticle plasmon coupled sensors doped within a lower Zeff material have been an effective way to achieve enhanced sensitivity of many dosimetry systems while still achieving tissue equivalency. These nanomaterial processing techniques and unique combinations of them are key steps that lead to the advanced features. Each must be realized through industrial production and quality control with packaging into dosimetry systems that maximize stability and reproducibility. Ultimately, recommendations for future work in this field of radiation dosimetry were summarized throughout the review.
Research progress of double perovskite ferroelectric thin films
Authors: Liu Xudong , Tu Jie , Li Hangren , Tian Jianjun , Zhang Linxing
Published: June 2023

Double perovskite ferroelectric thin films are completely new material systems derived from single perovskite. Their diversity of composition and structure and the tendency for spontaneous atomic ordering broaden the path for the development of ferroelectric thin films. The ordered double perovskite ferroelectric thin films lead to excellent ferroelectric, dielectric, magnetic, and optical properties, promising further applications in photovoltaic cells, information memory, and spintronic and photoelectric devices, where the intrinsic coupling and tuning of multiple properties could also push it into multifunctional intersecting devices. However, complex internal physical mechanisms and difficult preparation conditions have prevented its further development. Based on ordered/disordered ferroelectric thin films of double perovskites, this paper first discusses ordered characterization methods such as superstructure reflection/diffraction peaks, especially for epitaxial thin films, saturation magnetization (macroscopic), and scanning transmission electron microscopy (microscopic). In response to the generally poor ordering of present systems, the paper also reviews the internal structure of the material and the external synthesis conditions that affect the ordering, including the valence and radii of the cations, preparation methods, element substitution and strain engineering, in the hope of triggering further research into ordered double perovskite ferroelectrics. Combined with the current state of research on existing double perovskite ferroelectricity thin film systems, advances in the fields of ferroelectric photovoltaics, magnetoelectric coupling, dielectric tunability, resistive switching, and photoelectric coupling have been presented. Finally, the challenges facing the material system are discussed and an outlook is provided for the development of the field.
Mapping fluid structuration to flow enhancement in nanofluidic channels
Authors: Agarwal Ankit , Arya Vinay , Golani Bhushan , Bakli Chirodeep , Chakraborty Suman
Published: June 2023

Fluid flow in miniature devices is often characterized by a boundary “slip” at the wall, as opposed to the classical paradigm of a “no-slip” boundary condition. While the traditional mathematical description of fluid flow as expressed by the differential forms of mass and momentum conservation equations may still suffice in explaining the resulting flow physics, one inevitable challenge against a correct quantitative depiction of the flow velocities from such considerations remains in ascertaining the correct slip velocity at the wall in accordance with the complex and convoluted interplay of exclusive interfacial phenomena over molecular scales. Here, we report an analytic engine that applies combined physics-based and data-driven modeling to arrive at a quantitative depiction of the interfacial slip via a molecular-dynamics-trained machine learning algorithm premised on fluid structuration at the wall. The resulting mapping of the system parameters to a single signature data that bridges the molecular and continuum descriptions is envisaged to be a preferred computationally inexpensive route as opposed to expensive multi-scale or molecular simulations that may otherwise be inadequate to resolve the flow features over experimentally tractable physical scales.
Liquid–vapor phase transition process during underwater electrical wire explosion
Authors: Park Sungbin , Lee Hakmin , Chung Kyoung-Jae
Published: June 2023

The liquid–vapor two-phase region has attracted the attention of various fundamental studies and applications. To explore the liquid–vapor two-phase region, underwater electrical wire explosion (UEWE) is a useful tool. In this work, we observe two different mechanisms of the liquid–vapor transition in UEWE: volume vaporization and spinodal decomposition. The main factors through which the mechanisms occur are the heating power and pressure accumulation in the system during UEWE. From the electrical properties and shadowgraph images, the phase transition process of the exploding wire is analyzed. The effects of possible instabilities during the liquid–vapor phase transition are also discussed. We expect that the thermodynamic properties of the liquid–vapor two-phase region can be explored using the UEWE technique based on the understanding of the phase transition process.
Particle-in-cell simulations of collisionless perpendicular shocks driven at a laser-plasma device
Authors: Hao Yufei , Yang Zhongwei , Tang Huibo , Kong Xiangliang , Shan Lican
Published: June 2023

Experiments of generation of quasi-perpendicular collisionless shocks driven by laser plasma were performed at the Shenguang-II laser facility with intense lasers. Here, using a 1D particle-in-cell simulation code including protons, carbon ions, and electrons, we investigate the experimental shock formation via the interaction between the laser-ablated piston and ambient plasma magnetized by a large pre-existing magnetic field and the associated ion dynamics in more detail. Simulation results show that, given enough time and space, ambient protons and carbon ions can be reflected at the piston–ambient interface successively, which leads to the formation of corresponding shocks before the piston and interface. Electric fields associated with the initial interaction known as Larmor coupling and the shocks may accelerate ambient protons, carbon ions reflected at the interface or shocks, and piston ones transmitted to the ambient region before shock formation.
Systematic investigation of coupling between symmetric and antisymmetric stretches of D2O in CHCl3 by 2D IR
Authors: Kwon Hyejin , Osawa Koji , Seol Jin Gyu , Sung Siheon , Kim Doseok , Kim Yung Sam
Published: June 2023

The coupling between the symmetric (νs) and antisymmetric (νa) OD stretch modes of monomeric D2O in CHCl3 is investigated using polarization-dependent two-dimensional infrared (2D IR) spectroscopy supported by numerical 2D IR simulations based on the exciton-band theory. The relationship between the local modes’ and the exciton states’ parameters is systematically studied, including center frequencies, diagonal anharmonicities, coupling, and off-diagonal anharmonicity. The mean coupling between νs and νa is accurately evaluated to be −49.96 ± 0.14 cm−1. The degree of relaxation in the harmonic approximation is quantified, and the angle between the exciton-state dipoles is accurately evaluated to be 101.4° ± 3.6°. In addition, the effect of the local-mode frequency correlation on the resulting exciton-state frequency correlation and the spectral shape of the linear and 2D IR spectra are also investigated.
Pulse sequences for manipulating the spin states of molecular radical-pair-based electron spin qubit systems for quantum information applications
Authors: Pazera Gediminas J. , Krzyaniak Matthew D. , Wasielewski Michael R.
Published: May 2023

Molecular qubits are an emerging platform in quantum information science due to the unmatched structural control that chemical design and synthesis provide compared to other leading qubit technologies. This theoretical study investigates pulse sequence protocols for spin-correlated radical pairs, which are important molecular spin qubit pair (SQP) candidates. Here, we introduce improved microwave pulse protocols for enhancing the execution times of quantum logic gates based on SQPs. Significantly, this study demonstrates that the proposed pulse sequences effectively remove certain contributions from nuclear spin effects on spin dynamics, which are a common source of decoherence. Additionally, we have analyzed the factors that control the fidelity of the SQP spin state, following the application of the controlled-NOT gate. It was found that higher magnetic fields introduce a high frequency oscillation in the fidelity. Thereupon, it is suggested that further research should be geared toward executing quantum gates at lower magnetic field values. In addition, an absolute bound of the fidelity outcome due to decoherence is determined, which clearly identifies the important factors that control gate execution. Finally, examples of the application of these pulse sequences to SQPs are described.
Experimental study of a C-band long-pulse high-efficiency klystron-like relativistic cavity oscillator
Authors: Wu Yang
Published: June 2023

In this paper, a comparative investigation of a C-band long-pulse high-efficiency klystron-like relativistic cavity oscillator is carried out by using numerical simulation and practical experiments. It is indicated that owing to the improper configuration of the solenoid, some returning electrons originating from the cathode supporting rod would hit the entrance of the diode and shunt the input electric power. As a result, the startup process of the device is delayed and the saturated output power is decreased as well. In the initial experiment, the output power and the pulse duration are only about 3.2 GW and 78 ns, respectively. To eliminate the influence of the returning electrons, by increasing the turn number of the winding at both ends of the solenoid, the magnetic field at the diode region is enhanced so that the returning electrons could be guided to the shielding bowl in front of the insulator. As the shielding bowl is under the same potential as the cathode, the returning electrons would not shunt the input power. In contrast, after solenoid compensation, the output power of the device is increased to 4.4 GW at a diode voltage of 700 kV and a current of 14 kA, whereas the pulse duration is extended to 96 ns. Also, the corresponding conversion efficiency achieves about 45%.
Assessing the source of error in the Thomas–Fermi–von Weizsäcker density functional
Authors: Thapa Bishal , Jing Xin , Pask John E. , Suryanarayana Phanish , Mazin Igor I.
Published: June 2023

We investigate the source of error in the Thomas–Fermi–von Weizsäcker (TFW) density functional relative to Kohn–Sham density functional theory (DFT). In particular, through numerical studies on a range of materials, for a variety of crystal structures subject to strain and atomic displacements, we find that while the ground state electron density in TFW orbital-free DFT is close to the Kohn–Sham density, the corresponding energy deviates significantly from the Kohn–Sham value. We show that these differences are a consequence of the poor representation of the linear response within the TFW approximation for the electronic kinetic energy, confirming conjectures in the literature. In so doing, we find that the energy computed from a non-self-consistent Kohn–Sham calculation using the TFW electronic ground state density is in very good agreement with that obtained from the fully self-consistent Kohn–Sham solution.
CO2 reduction on adatom decorated platinum stepped surfaces
Authors: Kherbach Intissar , Climent Víctor , Feliu Juan M.
Published: June 2023

The rate of CO formation from CO2 reduction on Pt(111) vicinal surfaces containing (100) steps, Pt(S)[n(111) × (100)], has been investigated using cyclic voltammetry. To obtain further information about the different roles of terrace and step atoms in this reaction, selective modification of step sites with either bismuth or copper has been performed. In this way, two different mechanistic regimes have been differentiated, depending on the potential range. In the high potential region, between 0.2 and 0.4 V RHE, CO2 is activated on steps and proceeds to the formation of adsorbed CO even when there is no hydrogen adsorbed on the terrace. We suggest that protonation of the activated CO2 uses protons from the solution. In this potential range, the activity decreases after the selective blockage of step sites with bismuth, while the deposition of copper on steps increases the activity. Contrarily, in the low potential region, below 0.2 V RHE, the presence of copper on the steps does not increase the amount of CO formed from CO2 reduction. In fact, the amount of CO formed attains the same saturation value with or without copper. In addition, the CO formed in this potential region remains adsorbed near step sites as shown in the voltammetric profile. We rationalize these observations considering that, in this potential region, activated CO2 reacts with adsorbed hydrogen and the reactions stop when hydrogen near the steps is depleted.
Understanding the sources of error in MBAR through asymptotic analysis
Authors: Li Xiang Sherry , Van Koten Brian , Dinner Aaron R. , Thiede Erik H.
Published: June 2023

Many sampling strategies commonly used in molecular dynamics, such as umbrella sampling and alchemical free energy methods, involve sampling from multiple states. The Multistate Bennett Acceptance Ratio (MBAR) formalism is a widely used way of recombining the resulting data. However, the error of the MBAR estimator is not well-understood: previous error analyses of MBAR assumed independent samples. In this work, we derive a central limit theorem for MBAR estimates in the presence of correlated data, further justifying the use of MBAR in practical applications. Moreover, our central limit theorem yields an estimate of the error that can be decomposed into contributions from the individual Markov chains used to sample the states. This gives additional insight into how sampling in each state affects the overall error. We demonstrate our error estimator on an umbrella sampling calculation of the free energy of isomerization of the alanine dipeptide and an alchemical calculation of the hydration free energy of methane. Our numerical results demonstrate that the time required for the Markov chain to decorrelate in individual states can contribute considerably to the total MBAR error, highlighting the importance of accurately addressing the effect of sample correlation.
Confinement time and ambipolar potential in a relativistic mirror-confined plasma
Authors: Ochs Ian E. , Munirov Vadim R. , Fisch Nathaniel J.
Published: May 2023

Advanced aneutronic fusion fuels such as proton-Boron11 tend to require much higher temperatures than conventional fuels like deuterium–tritium. For electrons, the bulk plasma temperature can approach a substantial fraction of the rest mass. In a mirror confinement system, where the electrons are confined by an ambipolar potential of at least five electron temperatures, the tail electrons which can escape the potential are fully relativistic, which must be taken into account in calculating their confinement. In this paper, simple estimates are employed to extend the scaling of the confinement time into the relativistic regime. By asymptotically matching this scaling to known solutions in the non-relativistic limit, accurate forms for the confinement time (and thus, the ambipolar potential) are obtained. These forms are verified using finite-element-based Fokker–Planck simulations over a wide range of parameters. Comparing relativistic and nonrelativistic mirror-confined plasmas with the same ratio of confining potential |eϕ| to electron temperature Te and the same mirror ratio R, the net result is a decrease in the confinement time due to relativistic effects by a factor of S≡(1+15Te/8mec2)/(1+2|eϕ|/mec2).
High-throughput and machine learning approaches for the discovery of metal organic frameworks
Authors: Zhang Xiangyu , Xu Zezhao , Wang Zidi , Liu Huiyu , Zhao Yingbo , Jiang Shan
Published: June 2023

Metal-organic frameworks (MOFs) are promising nanoporous materials with diverse applications. Traditional material discovery based on intensive manual experiments has certain limitations on efficiency and effectiveness when faced with nearly infinite material space. The current situation offers an opportunity for high-throughput (HT) and machine learning (ML) approaches, including computational and experimental methods, as they have greatly improved the efficiency of MOF screening and discovery and have the capacity to deal with the enormous growth of data. In this review, we discuss the research progress in HT computation and experiments and their effect on MOF screening and discovery. We also highlight how ML-based approaches and the integration of HT methods with ML algorithms accelerate MOF design. In addition, we provide our insights on the future capability of data-driven techniques for MOF discovery, despite facing some knowledge gaps as an obstacle.
Comprehensive characterization of the adiabatic temperature change and (convection) heat transfer coefficient of a NiTi tube elastocaloric refrigerant
Authors: Cheng Siyuan
Published: June 2023

Elastocaloric cooling without global warming substance emission is a promising alternative to the vapor-compression technology. Comprehensive and precise characterization of the adiabatic temperature change of the elastocaloric refrigerant and the heat transfer coefficient between the elastocaloric refrigerant and the surrounding heat transfer fluid/solid is significant for the structural design of elastocaloric coolers. In this article, an analytical solution of the volume-averaged temperature variation in a tubular shape memory alloy elastocaloric refrigerant under cyclic compression was derived using lumped analysis, and a method of comprehensive characterization of the adiabatic temperature change (∆Tad) and (convection) heat transfer coefficient h for the elastocaloric refrigerant based on the analytical solution was proposed. A dimensionless number Ch was defined as the ratio of the latent heat release/absorption rate to the (convection) heat transfer rate, with which the characterization procedure including a series of nonlinear least-square regression tests and data selection criteria were established. The method proposed is applicable to any cross section geometry under both tension and compression, and it was validated using experimental data on a NiTi tube under sinusoidal force-controlled and reverse Brayton cyclic compressions and using existing experimental data of NiTi-based films, strips, and pillars under tension and compression in the literature. The ∆Tad characterized using the proposed method agreed with that using the reverse Brayton cyclic loading method within 5% (absolute value of 1 K). The effect of data selection sequence on the characterization of ∆Tad and h was investigated, and the results showed that proper starting points were significant for the convergence of ∆Tad and h.
Facile synthesis and excellent electromagnetic wave absorption properties of Air@RGO/CoNi hollow microspheres
Authors: Yu Qi , Xue Yanan , Nie Weicheng , Tang Yiming , Wang Yunlong , Du Chenglong
Published: May 2023

The rational synergy of chemical composition and spatial nanostructures plays an important role in high-performance electromagnetic wave (EMW) absorption materials. Here, reduced graphene oxide (RGO) hollow microspheres loaded with CoNi alloy nanoparticles (Air@RGO/CoNi) were constructed by a facile water-in-oil emulsification route followed by high-temperature thermal treatment. The crystal structure, composition, microstructure, and magnetic properties of Air@RGO/CoNi were characterized by XRD, XPS, TEM, and VSM, respectively. The results demonstrated that the as-obtained Air@RGO/CoNi composites showed a uniform spherical morphology with a remarkably hollow structure. Impressively, nano-CoNi particles were compactly and uniformly distributed on the surface of RGO. Benefiting from the unique structure and compositional merits, the optimized Air@RGO/CoNi hollow microspheres exhibit superior (EMW) absorption performance. The minimum reflection loss (RLmin) value reached up to −56.16 dB at 13.67 GHz with a thin thickness of 2.55 mm and the widest effective absorption bandwidth (RL values are below −10 dB) covered 8.65 GHz (9.15–17.8 GHz) with a thinner thickness of 2.4 mm. Furthermore, possible EMW attenuation mechanisms had been proposed. Given these outstanding findings, we believe the as-fabricated Air@RGO/CoNi hollow microspheres can be promising candidates as highly microwave absorption materials with thin thickness, wide absorption bandwidth, and high absorption capacity.
Dynamic high pressure phase transformation of ZrW2O8
Authors: Bishop Sean R. , Lowry Daniel R. , Peretti Amanda S. , Kalita Pat , Knudson Marcus D. , Sarracino Alex , Mahaffey Jacob T. , Murray Shannon E.
Published: June 2023

Phase transformations under high strain rates (dynamic compression) are examined in situ on ZrW2O8, a negative thermal expansion ternary ceramic displaying polymorphism. Amorphization, consistent with prior quasi-static measurements, was observed at a peak pressure of 3.0 GPa under dynamic conditions, which approximate those expected during fabrication. Evidence of partial amorphization was observed at lower pressure (1.8 GPa) that may be kinetically restrained by the short (<∼150 ns) time scale of the applied high pressure. The impact of kinetics of pressure-induced amorphization from material fabrication methods is briefly discussed.
CrB-type, ordered α-MnB: Single crystal structure and spin-canted magnetic behavior
Authors: Kalyon Nalan , Zieschang Anne-Marie , Hofmann Kathrin , Lepple Maren , Fries Maximilian , Skokov Konstantin P. , Dürrschnabel Michael , Kleebe Hans-Joachim , Gutfleisch Oliver , Albert Barbara
Published: June 2023

Manganese monoboride has a low- (α) and a high-temperature (β) modification, as well as a defect-rich low-temperature variant (α′). The crystal structure (FeB-type structure, s.g. Pnma) and properties of high-temperature MnB are well-known. In this work, single crystals were grown via chemical vapor transport reactions, both of β-MnB and the low-temperature modification, α-MnB. This allowed for determining the crystal structure of defect-free α-MnB [CrB-type structure, s.g. Cmcm, a = 3.0098(6) Å, b = 7.6390(2) Å, and c = 2.94620(6) Å]. Furthermore, α′-MnB, the stacking fault-dominated CrB-variant, was obtained as crystalline powder and characterized by X-ray powder diffraction and transmission electron microscopy. Direction-resolved measurements of the magnetic properties of α-MnB revealed spin-canted magnetic behavior along c and ferromagnetism along a and b with a Curie temperature of 456 K; ferromagnetic β-MnB has a Curie temperature of 568 K.
Bayesian optimization of metastable nickel formation during the spontaneous crystallization under extreme conditions
Authors: Malakpour Estalaki Sina , Luo Tengfei , Manukyan Khachatur V.
Published: June 2023

Spontaneous crystallization of metals under extreme conditions is a unique phenomenon occurring under far-from-equilibrium conditions that could enable the development of revolutionary and disruptive metastable metals with unusual properties. In this work, the formation of the hexagonal close-packed nickel (hcp-Ni) metastable phase during spontaneous crystallization is studied using non-equilibrium molecular dynamics (MD) simulations, with the goal of maximizing the fraction of this metastable phase in the final state. We employ Bayesian optimization (BO) with the Gaussian processes (GPs) regression as the surrogate model to maximize the hcp-Ni phase fraction, where temperature and pressure are control variables. MD simulations provide data for training the GP model, which is then used with BO to predict the next simulation condition. Such BO-guided active learning leads to a maximum hcp-Ni fraction of 43.38% in the final crystallized phase within 40 iterations when a face-centered cubic crystallite serves as the seed for crystallization from the amorphous phase. When an hcp seed is used, the maximum hcp-Ni fraction in the final crystal increases to 58.25% with 13 iterations. This study shows the promise of using BO to identify the process conditions that can maximize the rare phases. This method can also be generally applicable to process optimization to achieve target material properties.
Analytical modeling and performance evaluation of an adjustable permanent magnet linear eddy current brake with mechanical magnetic adjuster
Authors: Li Zhao , Wang Jialei , Li Yan , Yang Hui , Wang Dazhi
Published: June 2023

A novel mechanical flux-adjusting permanent magnet linear eddy current brake with high performance and its nonlinear analytical model are proposed. The innovative point lies in attaching an additional mechanical magnetic adjuster directly above the interior permanent magnet bar, which can achieve flexible adjustment of the air-gap flux and improve the generation capacity of the braking force and its regulation range. Considering the importance of the analytic model in practical design, the average air-gap flux density and eddy current density are estimated based on the equivalent magnetic circuit method and Ampere’s law, where the critical flux-weakening effect and leakage flux effect are calculated quantitatively. Then a practical theoretical model of braking force is derived based on the energy conversion and verified by the 3D finite-element method. Through analysis of the magnitude and regulation range of the braking force in a given range of speed, the advantages of the device and the electromagnetic force model are proved separately. Moreover, design suggestions for selecting the key geometrical parameters are further given, which offer useful information for pre-design and optimization.