bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive factors for the outcome of radioiodine therapy in patients with benign thyroid diseases
Authors: Wedel Florian , Exarchopoulos Thomas , Brenner Winfried
Published: January 2024

Purpose Radioiodine therapy (RIT) of benign thyroid diseases is an established therapy. This study aimed to identify factors predictive for outcome in patients with non-toxic goiter (NTG), unifocal (UFA), multifocal (MUFA) or diffuse autonomy (DISA) and Graves’ disease (GD).

Methods Retrospective analysis of 205 patients with benign thyroid disease (54 NTG, 46 MUFA, 24 DISA, 26 UFA, 55 GD) who underwent RIT. Follow up time was 12 months for determining treatment outcome.

Results The type of disease was predictive for volume reduction after 12 months (NTS 66%, DISA 67%, MUFA 58%, UFA 51%, GD 71%, p<0.001) and post-treatment hypothyroidism (NTS 48%, DISA 33%, MUFA 15%, UFA 15%, p=0.006). Initial volume, intra-therapeutic uptake and intra-therapeutic half-life were independent prognostic factors for volume reduction 12 months after RIT. In patients with NTG, UFA, MUFA, DISA post-treatment hypothyroidism was significantly correlated with extent of volume reduction 12 months after RIT, achieved dose, higher pre-therapeutic TSH values and younger age. Two different strategies for pre-therapeutic dosimetry used in MUFA showed no differences regarding the therapeutic outcome. In GD, effective half-life, initial volume and Graves’ ophthalmopathy were predictive for treatment failure.

Conclusion Reduction of thyroid volume and the percentage of hypothyroid patients one year after RIT was primarily dependent on the type of disease. In MUFA and DISA we could identify volume reduction after 3 months as a reliable predictor for hypothyroidism while in patients with GD a short intra-therapeutic half-life, a large pre-therapeutic volume and active Graves’ ophtalmopathy were relevant predictors for treatment failure suggesting an intensified follow-up scheme in these patients.
Effekte einer Entspannungspause auf die Gesundheit von Pflegenden
Authors: Berghoff Franziska , Rudolph Sabrina , Homm Alissa , Giro-Einfeldt Stephanie F.
Published: January 2024

Die Versorgung schwerstkranker Patienten ist physisch wie psychisch anspruchsvoll. Nicht selten leiden Pflegende unter gesundheitlichen Beeinträchtigungen. Ein wichtiger Faktor zur Gesunderhaltung ist, im Arbeitsalltag regelmäßige Pausen einzulegen und diese sinnvoll zu verbringen. Die Uniklinik Göttingen hat dafür ein spezielles System im Einsatz.
Anästhesieverfahren bei einer Switch-Operation bei Säuglingen
Authors: Weth Vanessa
Published: January 2024

Bei einer arteriellen Switch-Operation werden die vertauscht angelegten Schlagadern durchtrennt und an die jeweils andere Herzkammer angeschlossen. Der Eingriff muss innerhalb der ersten zwei Lebenswochen erfolgen. Welche anästhesiologischen Besonderheiten dabei zu beachten sind, zeigt ein Fallbeispiel.
The Role of FDG- PET/CT in Detecting Bone Marrow Involvement in Childhood Solid Tumors
Authors: Arslantaş Esra , Ayçiçek Ali , Esen Akkas Burcu , Tahtakesen Güçer Tuba Nur , Okur Acar Sultan , Özkan Karagenc Ayse , Akpınar Tekgündüz Sibel , Bayram Cengiz
Published: January 2024

Purpose To compare the results of 18F-Fluorodeoxy positron emission tomography/computed tomography (18 F-FDG-PET/CT) and bone marrow biopsy (BMB) procedures in the initial evaluation of bone marrow involvement (BMI) in pediatric solid tumors.

Methods We conducted a retrospective analysis of newly diagnosed pediatric cases with lymphoma, neuroblastoma, Ewing sarcoma, rhabdomyosarcoma. Each case underwent both PET-CT imaging and BMB. Presence of tumor infiltration in BMB specimens and/or positive FDG-PET/CT findings indicate as BMI were regarded as true positive results.

Results Sixty-four patients were included in the study. BMI was detected in 23/64 (36%) patients, FDG-PET/CT imaging and BMB results were concordant in 54/64 patients. In 9/64 patients the finding was FDG-PET/CT (+), BMB (-) indicating a false negative BMB result. In only 1/64 patients FDG- PET/CT (-), BMB (+), indicating a false negative FDG-PET/CT result. In the whole patient group, the sensitivity, specificity, positive predictive value and negative predictive value of PET/CT and BMB in detecting bone marrow involvement were 95.6%, 100%, 100% and 97.6% and 60.8 %, 100%, 100% and 82%, respectively.

Conclusion PET/CT has a high sensitivity and specificity for the assessing marrow involvement in pediatric solid tumors. We believe that PET/CT imaging should be performed as the first step in diagnostic staging, and BMB may not be necessary in every patient, only in patients with suspicious PET/CT results for bone marrow involvement. Additionally, for a more precise determination of bone marrow involvement, it is reasonable to perform BMB from FDG-retaining areas, using PET/CT as a guide tool.
Linked-color imaging with or without artificial intelligence for adenoma detection: a randomized trial
Authors: Miyaguchi Kazuya , Tsuzuki Yoshikazu , Hirooka Nobutaka , Matsumoto Hisashi , Ohgo Hideki , Nakamoto Hidetomo , Imaeda Hiroyuki
Published: January 2024

Background Adenoma detection rate (ADR) is an important indicator of colonoscopy quality and colorectal cancer incidence. Both linked-color imaging (LCI) with artificial intelligence (LCA) and LCI alone increase adenoma detection during colonoscopy, although it remains unclear whether one modality is superior. This study compared ADR between LCA and LCI alone, including according to endoscopists’ experience (experts and trainees) and polyp size.

Methods Patients undergoing colonoscopy for positive fecal immunochemical tests, follow-up of colon polyps, and abdominal symptoms at a single institution were randomly assigned to the LCA or LCI group. ADR, adenoma per colonoscopy (APC), cecal intubation time, withdrawal time, number of adenomas per location, and adenoma size were compared.

Results The LCA (n=400) and LCI (n=400) groups showed comparable cecal intubation and withdrawal times. The LCA group showed a significantly higher ADR (58.8% vs. 43.5%; P<0.001) and mean (95%CI) APC (1.31 [1.15 to 1.47] vs. 0.94 [0.80 to 1.07]; P<0.001), particularly in the ascending colon (0.30 [0.24 to 0.36] vs. 0.20 [0.15 to 0.25]; P=0.02). Total number of nonpolypoid-type adenomas was also significantly higher in the LCA group (0.15 [0.09 to 0.20] vs. 0.08 [0.05 to 0.10]; P=0.02). Small polyps (≤5, 6–9mm) were detected significantly more frequently in the LCA group (0.75 [0.64 to 0.86] vs. 0.48 [0.40 to 0.57], P<0.001 and 0.34 [0.26 to 0.41] vs. 0.24 [0.18 to 0.29], P=0.04, respectively). In both groups, ADR was not significantly different between experts and trainees.

Conclusions LCA was significantly superior to LCI alone in terms of ADR.
DNMT3A/TET2/ASXL1 Mutations are an Age-independent Thrombotic Risk Factor in Polycythemia Vera Patients: An Observational Study
Authors: Segura-Díaz Adrián , Stuckey Ruth , Florido Yanira , Sobas Marta , Álvarez-Larrán Alberto , Ferrer-Marín Francisca , Pérez-Encinas Manuel , Carreño-Tarragona Gonzalo , Fox María L. , Tazón Vega Barbara , Cuevas Beatriz , López Rodríguez Juan F. , Sánchez-Farías Nuria , González-Martín Jesús M. , Gómez-Casares María T. , Bilbao-Sieyro Cristina ,   on behalf of the Spanish MPN Group (GEMFIN)
Published: January 2024

Background Polycythemia vera (PV) patients are classified as high or low thrombotic risk based on age and prior history of thrombosis. Despite adherence to treatment recommendations, vascular events remain frequent, leading us to question whether thrombotic risk stratification could be improved. We previously reported an association between thrombotic events and mutations in DTA genes (DNMT3A, TET2, and ASXL1). The objective of this study was to confirm this observation in a larger series of PV patients.

Methods PV patients with a minimum follow-up of 3 years were recruited from 8 European centers. Medical history was searched for thrombotic event recorded at any time and next-generation sequencing carried out with a myeloid panel. Multivariable logistic regression evaluated the impact of variables on thrombotic risk. Kaplan–Meier thrombosis-free survival curves were compared by the log rank test. Associations in the total cohort were confirmed in a case–control study to exclude selection bias.

Results Of the 136 patients recruited, 74 (56.1%) had a thrombotic event, with an incidence density of 2.83/100 person-years. In multivariable analysis, DTA mutation was a risk factor for thrombotic event, being predictive for shorter thrombosis-free survival in the whole cohort (p = 0.007), as well as in low-risk patients (p = 0.039) and older patients (p = 0.009), but not for patients with a prediagnostic event. A gender- and age-matched case–control study confirmed the increased risk of thrombotic event for PV patients with a DTA mutation.

Conclusion Our results support the use of molecular testing at diagnosis to help predict which PV patients are at higher risk of developing thrombosis.
Implicit Bias and Health Disparities Education in the Neonatal Intensive Care Unit
Authors: Dyess Nicolle Fernández , Carr Cara Beth , Mavis Stephanie C. , Caruso Catherine G. , Izatt Susan , French Heather , Dadiz Rita , Bonachea Elizabeth M. , Gray Megan M.
Published: January 2024

Objective This study aimed to characterize implicit bias (IB) and health disparities (HD) education in neonatal–perinatal medicine (NPM), including current educational opportunities, resources, and barriers.

Study Design A national web-based survey was sent to NPM fellows, neonatologists, and frontline providers after iterative review by education experts from the National Neonatology Curriculum Committee. Quantitative data were analyzed with chi-square and Fisher's exact tests. Qualitative data were evaluated using thematic analysis.

Results Of the 452 NPM survey respondents, most desired additional IB (76%) and HD (83%) education. A greater proportion of neonatologists than fellows received IB (83 vs. 57%) and HD (87 vs. 74%) education. Only 41% of neonatologists reported that their institution requires IB training. A greater proportion of fellows than neonatologists expressed dissatisfaction with the current approaches for IB (51 vs. 25%, p < 0.001) and HD (43 vs. 25%, p = 0.015) education. The leading drivers of dissatisfaction included insufficient time spent on the topics, lack of specificity to NPM, inadequate curricular scope or depth, and lack of local educator expertise. A minority of faculty who were tasked to educate others have received specific educator training on IB (21%) and HD (16%). Thematic analysis of survey free-text responses identified three main themes on the facilitators and barriers to successful IB and HD education: individual, environmental, and curricular design variables.

Conclusion NPM trainees and neonatologists desire tailored, active, and expert-guided IB and HD education. Identified barriers are important to address in developing an effective IB/HD curriculum for the NPM community.

Key Points
Effect of an E-learning resource on endoscopists’ proximal serrated polyp detection rate: a randomized controlled trial
Authors: van Toledo David E. F. W. M. , IJspeert Joep E. G. , Bleijenberg Arne G. C. , Depla Anne , Montazeri Nahid S. M. , Dekker Evelien
Published: January 2024

Background Recent studies demonstrated that a higher proximal serrated polyp detection rate (PSPDR) among endoscopists is associated with a lower risk of post-colonoscopy colorectal cancer (PCCRC) incidence and death for their patients. Our objective was to evaluate the effect of an e-learning resource on PSPDR.

Methods We performed a multicenter randomized controlled trial within the Dutch fecal immunochemical test-based colorectal cancer screening program. Endoscopists were randomized using block randomization per center to either receive a 60-minute e-learning resource on serrated polyp detection or not. PSPDR was calculated based on all colonoscopies performed during a 27-month pre-intervention and a 17-month post-intervention period. The primary end point was difference in PSPDR between intervention and control arms (intention to treat) using mixed effect logistic regression modeling, with time (pre-intervention/post-intervention) and interaction between time and arm (intervention/control) as fixed effects, and endoscopists as random effects.

Results 116 endoscopists (57 intervention, 59 controls) were included, and performed 27494 and 33888 colonoscopies, respectively. Median PSPDR pre-intervention was 13.6% (95%CI 13.0–14.1) in the intervention arm and 13.8% (95%CI 13.3–14.3) in controls. Post-intervention PSPDR was significantly higher over time in the intervention arm than in controls (17.1% vs. 15.4%, P=0.01).

Conclusion In an era of increased awareness and increasing PSPDRs, endoscopists who undertook a one-time e-learning course significantly accelerated the increase in PSPDR compared with endoscopists who did not undertake the e-learning. Widespread implementation might reduce PCCRC incidence.
Recent Advances in the Multicomponent Synthesis of Heterocycles Using 5-Aminotetrazole
Authors: Javahershenas Ramin , Makarem Ata , Mei Haibo , Koley Manankar , Soloshonok Vadim A.
Published: January 2024

The unique reactivity and beneficial features of the 5-aminotetrazole synthon (1H-tetrazol-5-amine) have made it a versatile and effective building block in the synthesis of heterocyclic compounds. In addition, several drugs containing this scaffold with a wide array of biological properties have been already introduced. Heterocyclic structures are the backbone of many biologically active and industrially important compounds. 5-Aminotetrazole is one of the favored synthons used in the preparation of heterocycle-bearing compounds, especially in multicomponent synthesis. This review highlights a comprehensive overview of the emerging applications of 5-aminotetrazole as a key component in the synthesis of heterocyclic frameworks through multicomponent reactions, reported between 2017 and July 2023.

1 Introduction

2 5-Aminotetrazole

3 Tetrazolopyrimidine Compounds

4 Spiro Compounds

5 Miscellaneous

6 Conclusion
Low-carbon transition and energy poverty: quasi-natural experiment evidence from China’s low-carbon city pilot policy
Authors: Xiao Yiming , Feng Zhijun , Li Xinying , Wang Shangrui
Published: January 2024

Low-carbon transition stands as a vital strategy for the global community to address the challenge of climate change, inevitably affecting residents’ daily lives. However, there is a notable gap in the quantitative analysis of the low-carbon transition’s impact on energy poverty in developing countries, limiting policymakers’ understanding of the inherent mechanism and their ability to take informed actions. This study investigates the low-carbon city pilot (LCCP) policy, China’s key low-carbon initiative, as a quasi-natural experiment, using the difference-in-differences (DID) method to examine its impact on residents’ energy poverty conditions. Utilizing panel data from 4807 households in the CHARLS dataset, this study effectively integrated household-level and city-level data. Benchmark regression indicates that the LCCP policy exacerbates energy poverty among residents. Further analysis reveals the pivotal role of energy infrastructure and expenditure in bridging the nexus between the LCCP policy and energy poverty, providing crucial insights into the potential pathways through which this policy impacts energy poverty. Additionally, heterogeneity analysis indicates that the impacts of LCCP policy are more pronounced in eastern cities, non-resource cities, and high administrative-level cities, as well as in the communities suffering from subpar governance quality. By leveraging reliable survey data and robust quantitative methods, this study not only broadens the methodology of energy poverty studies but also offers valuable insights for developing countries to safeguard residents’ energy welfare amid low-carbon transitions.
Stakeholders’ perspective on collaboration barriers in low-income housing provision: a case study from pakistan
Authors: Malik Sana , Nurunnabi Mohammad
Published: January 2024

The prevailing housing situation in Pakistan is alarming, as more than 47% of urban households are estimated to be living in squatters. Housing stakeholders require an enabling environment to collaborate to reduce the drastic inequity with too many housing options for the high-income and too few for the low-income groups. Existing literature reveals that Pakistan lacks stakeholder studies with a collaborative focus on providing low-income housing in urban areas. This study explores the barriers and impediments to stakeholder collaborations in the low-income housing sector through in-depth interviews within the urban setting of Lahore, the capital and the most populous city of the biggest province, Punjab, Pakistan. The findings identify the emergence of five cross-cutting collaboration challenges (GLIPP), placing government capacity, institutional complexity, and political willpower & intervention as dominant ones. This study stresses revising the organizational hierarchy of government institutions to develop a collaborative culture in the Pakistani housing sector. As part of practical implications, this paper would agitate policymakers to develop housing policies and programs for low-income groups.
Dynamical confinement for Schrödinger operators with magnetic potential and Aharonov–Bohm effect
Authors: de Oliveira C. R. , Romano R. G.
Published: January 2024

A magnetic potential is included in the so-called (quantum) dynamical confinement to open sets of Rd; gauge transformations are also discussed. Then, the results are applied to the Aharonov–Bohm model in the plane (the solenoid is a disk of radius greater than zero) in order to get some examples of operators confining the electron outside the solenoid.
A dynamic wall modeling approach for large eddy simulation of offshore wind farms in realistic oceanic conditions
Authors: Aiyer A. K. , Deike L. , Mueller M. E.
Published: January 2024

Due to the multitude of scales present in realistic oceanic conditions, resolving the surface stress is computationally intensive, motivating modeling approaches. In this work, a dynamic wave drag model is developed for large eddy simulation (LES) to quantify the effects of multiscale dynamically rough surfaces on the atmospheric boundary layer. The waves are vertically unresolved, and the total drag due to the horizontally resolved portion of the wave spectrum is computed through a superposition of the force from each mode. As LES can only resolve the horizontal wind–wave interactions to the filter scale Δ, the effects of the horizontally unresolved, subfilter waves are modeled by specifying a roughness length scale characterizing the unresolved wave energy spectrum. This subfilter roughness is set proportional to the subfilter root mean square of the wave height distribution, and the constant of proportionality is evaluated dynamically during the simulation based on the assumption that the total drag force at the wave surface is independent of the filter scale. The dynamic approach is used to simulate the airflow over a spectrum of moving waves, and the results are validated against high-fidelity phase-resolved simulations. The dynamic approach combined with the wave spectrum drag model is then used to study flow through a fixed-bottom offshore wind farm array, equivalent to an infinite farm, with each turbine represented using an actuator disk model. The dynamic model accurately adapts to the changing velocity field and accurately predicts the mean velocity profiles and power produced from the offshore wind farm. Furthermore, the effect of the wind–wave interactions on the mean velocity profiles, power production, and kinetic energy budget is quantified.
The development of internal pressure standards for in-house elastic wave velocity measurements in multi-anvil presses
Authors: Néri A. , Man L. , Chantel J. , Farla R. , Bauer G. , Linhardt S. , Boffa Ballaran T. , Frost D. J.
Published: January 2024

Ultrasonic systems are powerful tools to determine elastic wave velocities of minerals and materials at high pressure and temperature and have been extensively developed in recent decades. However, accurate measurement of sample length is required to convert travel times into wave velocities, limiting their use to synchrotron facilities or room temperature experiments in laboratories. We have made use of a close collaboration between the Bayerisches Geoinstiut and the P61B end-station beamline (PETRA III - DESY) to install ultrasonic systems and develop a novel dual travel time method for in situ pressure determination without the need for synchrotron radiation. Our method relies on the travel times of elastic waves through a reference material; it requires a thermocouple and is non-intrusive, with the reference material replacing the backing plate of the high-pressure assembly. Pressures obtained from this dual travel time method show excellent agreement with those obtained from x-ray diffraction using synchrotron radiation on standard materials. Our novel method enables in situ pressure determination at varying temperatures during in-house ultrasonic interferometry experiments. This allows us not only to determine the elastic behavior of minerals and materials but also to investigate phase diagrams, solidus, or liquidus conditions at varying pressures and temperatures during in-house experiments. During the installation of the pulse-echo ultrasonic system, we identified critical parameters for obtaining reliable data. While these requirements are well-known to experts, this study presents a comprehensive review of the different characteristics of ultrasonic systems, providing user-friendly guidelines for new users installing and operating such systems in high-pressure and high-temperature conditions.
Exploring unique dynamics in a predator–prey model with generalist predator and group defense in prey
Authors: Srivastava Vaibhava , Antwi-Fordjour Kwadwo , Parshad Rana D.
Published: January 2024

In the current paper, we consider a predator–prey model where the predator is modeled as a generalist using a modified Leslie–Gower scheme, and the prey exhibits group defense via a generalized response. We show that the model could exhibit finite-time blow-up, contrary to the current literature [Patra et al., Eur. Phys. J. Plus 137(1), 28 (2022)]. We also propose a new concept via which the predator population blows up in finite time, while the prey population quenches in finite time; that is, the time derivative of the solution to the prey equation will grow to infinitely large values in certain norms, at a finite time, while the solution itself remains bounded. The blow-up and quenching times are proved to be one and the same. Our analysis is complemented by numerical findings. This includes a numerical description of the basin of attraction for large data blow-up solutions, as well as several rich bifurcations leading to multiple limit cycles, both in co-dimension one and two. The group defense exponent p is seen to significantly affect the basin of attraction. Last, we posit a delayed version of the model with globally existing solutions for any initial data. Both the ordinary differential equation model and the spatially explicit partial differential equation models are explored.
Dynamics of the plasma induced by laser on a cryogenically cooled aluminum target for application in space propulsion
Authors: Robledo-Martinez A. , Sobral H. , Garcia-Villarreal L. A.
Published: January 2024

In this work, we investigate the properties of the plasma induced by focusing a high-power laser beam on an aluminum target that was cooled by a helium refrigerator from room temperature down to 20 K. Fast, streak photographs of the plasma were taken at different temperatures and laser energies. From the images obtained, position-vs-time plots were made for each experiment, and from them, the speed was calculated. Additionally, narrowband interference filters were employed to image the dynamics of ions and neutrals separately. It was found that the plasma plume has two distinct speeds: that of its center and that of the outer edge. For unfiltered images, the former has values within the interval 6.2 to 9.1 km/s, while the latter can reach speeds of the order of hundreds of km/s. It was found that the plume of a target cooled to 20 K has a length that is 8%–12% less than the corresponding size at room temperature. Chilling the target did not seem to affect significantly either the plume's speed of expansion or the size of the crater produced. Lower bounds were estimated for the momentum imparted to the ejecta and the specific impulse. The latter can reach a 920-s level, nearly twice as much the amount obtained with chemical rocket fuel.
Understanding electronic structure tunability by metal dopants for promoting MgB2 hydrogenation
Authors: Lefcochilos-Fogelquist H. M. , Wan L. F. , Rowberg A. J. E. , Kang S. , Stavila V. , Klebanoff L. E. , Allendorf M. D. , Wood B. C.
Published: January 2024

Hydrogen is a promising energy carrier, but its onboard application is limited by the need for compact, low-pressure storage solutions. Solid-state complex metal hydride systems, such as MgB2/Mg(BH4)2, offer high storage capacities but suffer from sluggish kinetics and poor reversibility. One avenue for improving reactivity is to introduce metal dopants to alter electronic and atomic properties, but the role of these chemical additives remains poorly understood, particularly for the hydrogenation reaction. In this work, we used density functional theory calculations on model MgB2 systems to rationalize the potential role of metal dopants in destabilizing B–B bonding within the MgB2 lattice. We carried out detailed electronic structure analyses for 28 different metal dopant adatoms to identify properties that contribute to a dopant’s efficacy. Based on the simulation results, we propose that an intermediate ionic and covalent character of the bonds between adatoms and B atoms is desirable for facilitating charge redistribution, disrupting the B–B bond network, and promoting H2 dissociation and H atom chemisorption on MgB2.
Higher-order interactions induce anomalous transitions to synchrony
Authors: León Iván , Muolo Riccardo , Hata Shigefumi , Nakao Hiroya
Published: January 2024

We analyze the simplest model of identical coupled phase oscillators subject to two-body and three-body interactions with permutation symmetry and phase lags. This model is derived from an ensemble of weakly coupled nonlinear oscillators by phase reduction, where the first and second harmonic interactions with phase lags naturally appear. Our study indicates that the higher-order interactions induce anomalous transitions to synchrony. Unlike the conventional Kuramoto model, higher-order interactions lead to anomalous phenomena such as multistability of full synchronization, incoherent, and two-cluster states, and transitions to synchrony through slow switching and clustering. Phase diagrams of the dynamical regimes are constructed theoretically and verified by direct numerical simulations. We also show that similar transition scenarios are observed even if a small heterogeneity in the oscillators’ frequency is included.
Hydrodynamic cavitation of nematic liquid crystal in Stokes flow behind bluff body with different shapes in microchannel
Authors: Yu Jia-Jia , Jiang Lu-Yang , Huang Li , Li Gu-Yuan , Bake Maitiniyazi , Li You-Rong
Published: January 2024

Hydrodynamic cavitation, which occurs when the local pressure is below the saturated vapor pressure in hydrodynamic flow, is ubiquitous in fluid dynamics and implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. In this paper, the hydrodynamic cavitation in the bluff body bypass flow of nematic liquid crystal 5CB in the microchannel is experimentally investigated. By 5CB, we mean the thermotropic liquid crystal 4′-pentyl-4-biphenylcarbonitrile. When the Reynolds number is in the range of 3 × 10−4 < Re < 1.2 × 10−3, a special flow phenomenon behind the bluff body is observed, namely, the disclination loop. The critical Reynolds number of cavitation inception varies with the shape of the bluff body, while the lowest value corresponds to the triangular bluff body. The hydrodynamic cavitation occurs in the Stokes flow regime with the Reynolds number significantly lower than 0.1 for all bluff bodies. There is a close relation between the oscillation behavior of cavitation domains and the structure of the bluff body. In addition, the pressure difference between the inlet and outlet of the microchannel shows linear relation with the Reynolds number rather than the quadratic relation for isotropic fluids, which proves the presence of shear thinning in the flow of nematic liquid crystals. The study in this paper on the hydrodynamic cavitation of nematic liquid crystal can broaden the research on providing new approaches for the enhancement of fluid mixing and heat transfer in microfluidic chips.
Controlling the nonadiabatic dynamics of the charge-transfer process with chirped pulses: Insights from a double-pump time-resolved fluorescence spectroscopy scheme
Authors: Soh Jia Hao , Jansen Thomas L. C. , Palacino-González Elisa
Published: January 2024

The manipulation of the ultrafast quantum dynamics of a molecular system can be achieved through the application of tailored light fields. This has been done in many ways in the past. In our present investigation, we show that it is possible to exert specific control over the nonadiabatic dynamics of a generic model system describing ultrafast charge-transfer within a condensed dissipative environment by using frequency-chirped pulses. By adjusting the external photoexcitation conditions, such as the chirp parameter, we show that the final population of the excitonic and charge-transfer states can be significantly altered, thereby influencing the elementary steps controlling the transfer process. In addition, we introduce an excitation scheme based on double-pump time-resolved fluorescence spectroscopy using chirped-pulse excitations. Here, our findings reveal that chirped excitations enhance the vibrational system dynamics as evidenced by the simulated spectra, where a substantial signal intensity dependence on the chirp is observed. Our simulations show that chirped pulses are a promising tool for steering the dynamics of the charge-transfer process toward a desired target outcome.
Enabling rotation over electrophoretic motion in Janus particles under applied electric field
Authors: Lee Ji-Young , Alú Andrea , Deravi Leila F.
Published: January 2024

Janus particles (JPs) comprising metal and dielectric halves are capable of propulsion perpendicular to an applied electric field, with promising applications in targeted drug delivery and microrobotics. Yet, not all JP geometries behave the same when activated. We explore hemispherical, snowman, and matchstick-like particle dynamics and evaluate threshold values for which electric torque can overcome induced charge electrophoresis. We define conditions where JPs are more likely to undergo rotation in place rather than linear motion, highlighting design features which should be considered when using these particles as materials.
Photovoltaic limitations of FAPbI3 nanocrystal solar cells associated with ligand washing processes
Authors: Galatopoulos F. , Papagiorgis P. , Ioakeimidis A. , Chrusou A. Z. , Souzou A. , Christodoulou C. , Bernasconi C. , Bodnarchuk M. I. , Leontidis E. , Kovalenko M. V. , Itskos G. , Choulis S. A.
Published: January 2024

The processing of perovskite nanocrystals (PNCs) solar cells (SCs) usually incorporates ligand washing (LW) procedures. We show that a LW step of FAI in EtAc assists in the removal of the oleic acid/oleylamine ligands and improves the JSC and FF values of FAPbI3 based SCs. Although by increasing the exposure time of EtAc the removal of oleic acid/oleylamine ligands is more effective, sintering/necking of the FAPbI3 results to NC agglomerations and formation of defects/traps are observed within the active layer by the reported photoluminescence studies. Despite identifying the balanced in LW procedure exposure time, limitations on the performance of FAPbI3 PNCs SCs are reported. To identify the photovoltaic limitations impedance spectroscopy studies are presented and show that in the case of FAPbI3 PNC SCs an intermediate frequency response manifests. The observed impedance spectroscopy intermediate frequency response correlates with a parasitic resistance effect, indicating charge transport limitations and charge recombination losses even after the applied LW processing procedure.
Allotropic transition of Dirac semimetal α-Sn to superconductor β-Sn induced by focused-ion-beam irradiation
Authors: Inagaki Kohdai , Ishihara Keita , Hotta Tomoki , Seki Yuichi , Takeda Takahito , Ishida Tatsuhiro , Ootsuki Daiki , Kawasaki Ikuto , Fujimori Shin-Ichi , Tanaka Masaaki , Anh Le Duc , Kobayashi Masaki
Published: January 2024

Diamond-type structure allotrope α-Sn is attracting much attention as a topological Dirac semimetal (TDS). In this study, we demonstrate that α-Sn undergoes a phase transition to another allotrope β-Sn with superconductivity at low temperature by irradiating with a focused Ga ion beam (FIB). To clarify the transition mechanism, we performed x-ray photoemission spectroscopy (XPS) measurements on an α-Sn thin film irradiated with FIB and an as-grown α-Sn thin film. The XPS results suggest that the local annealing, which is one of the side effects of FIB, causes the transformation from α-Sn into β-Sn. Furthermore, the difference in the chemical states between α-Sn and β-Sn can be quantitatively explained by the crystal structures rather than the degree of metallicity reflecting the conductivity. These results propose a way of fabricating TDS/superconductor in-plane heterostructures based on α-Sn and β-Sn.
Data-driven dynamical coarse-graining for condensed matter systems
Authors: del Razo Mauricio J. , Crommelin Daan , Bolhuis Peter G.
Published: January 2024

Simulations of condensed matter systems often focus on the dynamics of a few distinguished components but require integrating the full system. A prime example is a molecular dynamics simulation of a (macro)molecule in a solution, where the molecule(s) and the solvent dynamics need to be integrated, rendering the simulations computationally costly and often unfeasible for physically/biologically relevant time scales. Standard coarse graining approaches can reproduce equilibrium distributions and structural features but do not properly include the dynamics. In this work, we develop a general data-driven coarse-graining methodology inspired by the Mori–Zwanzig formalism, which shows that macroscopic systems with a large number of degrees of freedom can be described by a few relevant variables and additional noise and memory terms. Our coarse-graining method consists of numerical integrators for the distinguished components, where the noise and interaction terms with other system components are substituted by a random variable sampled from a data-driven model. The model is parameterized using data from multiple short-time full-system simulations, and then, it is used to run long-time simulations. Applying our methodology to three systems—a distinguished particle under a harmonic and a bistable potential and a dimer with two metastable configurations—the resulting coarse-grained models are capable of reproducing not only the equilibrium distributions but also the dynamic behavior due to temporal correlations and memory effects. Remarkably, our method even reproduces the transition dynamics between metastable states, which is challenging to capture correctly. Our approach is not constrained to specific dynamics and can be extended to systems beyond Langevin dynamics, and, in principle, even to non-equilibrium dynamics.
Feel the force: From local surface pressure measurement to flow reconstruction in fluid–structure interaction
Authors: Rodwell Colin , Sourav Kumar , Tallapragada Phanindra
Published: January 2024

Drawing inspiration from the lateral lines of fish, the inference of flow characteristics via surface-based data has drawn considerable attention. The current approaches often rely on analytical methods tailored exclusively for potential flows or utilize black-box machine learning algorithms to estimate a specific set of flow parameters. In contrast to a black-box machine learning approach, we demonstrate that it is possible to identify certain modes of fluid flow and then reconstruct the entire flow field from these modes. We use dynamic mode decomposition to parametrize complex, dynamic features across the entire flow field. We then leverage deep neural networks to infer the dynamic modes of the pressure and velocity fields within a large, unsteady flow domain, employing solely a time series of pressure measurements collected on the surface of an immersed obstacle. Our methodology is successfully demonstrated to diverse fluid–structure interaction scenarios, including cases with both free oscillations in the wake of a cylinder and forced oscillations of tandem cylinders, demonstrating its versatility and robustness.
Effect of Oldroyd-B fluid on thermal convection stability in a bidispersive porous media with relatively large macropores
Authors: Jia Beinan , Jian Yongjun
Published: January 2024

This study investigates the effect of Oldroyd-B fluids on the thermal convection instability in a bi-disperse porous medium with relatively large macropores. The modified momentum equation of Oldroyd-B fluid in the macro- and micropores is first derived, assuming local thermal equilibrium. The Orr–Sommerfeld (O–S) equation is derived using the new modified incompressible Navier–Stokes equations of Oldroyd-B fluid. The Chebyshev collocation method is employed to solve the generalized eigenvalue problem, and the neutral stability curves and temporal growth rates are obtained. The results demonstrate that the relaxation time enhances the convective instability, while the retardation time suppresses it. Furthermore, the effect of relaxation time is generally small for smaller wave number, but the effect of relaxation time is significant for large wave number, and this effect becomes accentuated as the wave number increases. The retardation time does not have any influence when the wavenumber is small, and the influence of retardation time becomes small with the large relaxation time. Moreover, the convection instability is enhanced with the higher micropermeability and a higher ratio of momentum transfer coefficient between the macro- and microphases will suppress the instability.
Navigating vortex gust interactions and mitigations by plunging wings
Authors: Panta Kundan , Deng Hankun , Cheng Bo , Panah Azar
Published: January 2024

Inspired by the stability achieved by biological flapping-winged fliers in gusty environments, we conducted particle image velocimetry studies on the interactions between plunging wings and large-scale vortex gusts. Our experiments involved a flat plate wing performing sinusoidal plunging motions at various frequencies, resulting in Strouhal numbers (St) ranging from 0 to 0.5 within which biological fliers commonly operate. This range of St corresponded to reduced frequencies (k) between 0 and 0.79 at a chord Reynolds number of 2000. The gust structures, generated periodically by pitching vanes, traveled downstream to the wing. We observed the vortex interactions between wing-induced vortices [particularly the boundary layer and the leading-edge vortex (LEV)] and the gusts. Additionally, we quantified the gusts' effects on the local flow around the wing by calculating the circulation within a control region attached to the plunging wing. The wing-induced vorticity merged momentarily with gusts of the same-sign vorticity. In contrast, opposite-sign gusts not only increased the circulation of the wing-induced vortices but also led to the LEV detaching faster. While gusts had the potential to significantly alter the flow around the wings, the plunging wings sometimes managed to avoid the gusts due to their transverse motion. Furthermore, the prolonged presence of the stronger LEVs near the wing, which are characteristic of plunging wings at higher St and k, could deflect the gusts away, reducing their impact on the vorticity and circulation within the control region. These findings illustrate how robust flapping kinematics can mitigate the effects of vortex gusts.
Enhanced minority carrier lifetime in bulk hydrogen-passivated InAsSbBi
Authors: Estévez H Félix A. , Bergthold M. , Maksimov Oleg , Bhandari Harish B. , Morath Christian P. , Duchane Alexander W. , Webster Preston T. , Wasserman D.
Published: January 2024

We investigate the bulk passivation of the dilute bismide alloy InAsSbBi by plasma-assisted hydrogenation. InAsSbBi is of significant interest for mid- to long-wave infrared photodetection due to its bandgap flexibility and potential integration with heterostructured photodetector architectures. Epitaxially grown InAsSbBi samples are characterized by photoluminescence and time-resolved photoluminescence measurements for a range of hydrogenation conditions. Increases in the minority carrier lifetime of over 3× are reported, with no degradation over a period of months following the treatment. Photoluminescence measurements confirm that the hydrogenation process improves the InAsSbBi optical properties. These results offer a path toward the improved performance of InAsSbBi-based photodetectors and potentially other narrow bandgap semiconductor materials and material systems.
Bottom-to-top modeling of epoxy resins: From atomic models to mesoscale fracture mechanisms
Authors: Konrad Julian , Zahn Dirk
Published: January 2024

We outline a coarse-grained model of epoxy resins (bisphenol-F-diglycidyl-ether/3,5-diethyltoluene-2,4-diamine) to describe elastic and plastic deformation, cavitation, and fracture at the μm scale. For this, molecular scale simulation data collected from quantum and molecular mechanics studies are coarsened into an effective interaction potential featuring a single type of beads that mimic 100 nm scale building blocks of the material. Our model allows bridging the time–length scale problem toward experimental tensile testing, thus effectively reproducing the deformation and fracture characteristics observed for strain rates of 10−1 to 10−5 s−1. This paves the way to analyzing viscoelastic deformation, plastic behavior, and yielding characteristics by means of “post-atomistic” simulation models that retain the molecular mechanics of the underlying epoxy resin at length scales of 0.1–10 µm.
Research on the swimming performance of two manta rays under staggered propulsion on the same frequency: When the follower is above the leader
Authors: Gao Pengcheng , Tian Xushun , Huang Qiaogao , Pan Guang
Published: January 2024

To investigate the hydrodynamic performance of two manta rays swimming in groups under staggered formation, first, a computational model and motion equations of manta rays were established based on biological observations, and then numerical simulations were carried out based on immersed boundary method to simulate the group swimming of manta rays with the same vertical spacing but with a changing streamwise spacing. The results showed that when the streamwise spacing is small between the two manta rays, the hydrodynamic performance decreases dramatically compared to individual swimming. As the streamwise spacing increases, the hydrodynamic performance of the leader is always better than that of individual swimming, and the thrust enhancement is maximized to 10.984% and the efficiency enhancement is maximized to 3.369% when the spacing is 0.4BL. As the streamwise spacing increases, the hydrodynamic performance of the follower shows greater volatility, with a maximum thrust enhancement of 47.923% when the spacing is 0.4BL, and a maximum efficiency enhancement of 14.017% when the spacing is 0.5BL. The system's average thrust gain is maximized at 29.454% when the spacing is 0.4BL, and the system's average efficiency gain is maximized at 7.689% when the spacing is 0.5BL.
Wake flow structure and hydrodynamic characteristics of flow around a C-shaped cylinder with variable attack angle at low Reynolds numbers
Authors: Gao Yue , Zhu Hongjun , Zhou Xinyu , Alam Md. Mahbub , Zhou Tongming , Tang Tao
Published: January 2024

A numerical investigation is conducted on the flow over a C-shaped cylinder in the low Reynolds number range of Re = 40–160. The effect of attack angle (α) ranging from 0° to 180° is examined simultaneously. Wake evolution and vortex structure as well as the hydrodynamic characteristics are analyzed. Seven flow patterns are identified based on the location of boundary layer separation points and the evolution of near-wall vortices. The boundary layer separation points lock on the two ends of the C-shaped cylinder, resulting in the typical Karman vortex street (Pattern I). A separation point shifts to the curved surface in Pattern II-1 and Pattern II-2, and a quasi-stagnation vortex (QS) is formed within the groove in Pattern II-2. In Pattern III-1 and Pattern III-2, the QS fills the groove. The subordinate vortex is observed in the groove close to the lower end (Pattern IV). The complicated vortex merging occurs around the lower end in Pattern V. The separation points lock on the two ends, exhibiting a pair of counter-rotating vortex shedding downstream of the two ends (Pattern VI). No vortex shedding is found in Pattern VII. Additionally, the characteristic parameters and the hydrodynamic coefficients are related, and they are associated with the flow pattern partition. Four types of vortex street are identified in the wake of the C-shaped cylinder, including no vortex street, 2S vortex mode and decayed vortex street, 2S vortex mode and secondary vortex street (2S-SVS), and P + S vortex mode and secondary vortex street in vortex evolution (P + S-SVS).
An active learning SPH method for generalized Newtonian free surface flows
Authors: Dong Xuekai , Wang Xiaodong , Ouyang Jie
Published: January 2024

This paper presents an active learning smoothed particle hydrodynamics (ALSPH) method to simulate generalized Newtonian free surface flows. First, an improved smoothed particle hydrodynamics (ISPH) method is established to obtain more reliable results for free surface flows by coupling the modified kernel gradient, the artificial viscosity, the density diffusive term, and the optimized particle shifting technique. Second, based on data and Gaussian process regression (GPR), an active learning strategy is developed to provide an effective constitutive relation. It is the first time that the ISPH method is combined with GPR to simulate generalized Newtonian free surface flows. Not only can the constitutive relation of any generalized Newtonian fluid in nature be accurately predicted, but a small amount of sampling data is also able to ensure accuracy over a wide range of the shear deformation rate. The challenging droplet impact and dam break are first modeled to validate the ISPH method. Due to the lack of an analytical constitutive relation for an arbitrary generalized Newtonian fluid in nature, the Cross model is then adopted and offers the required data to validate the ALSPH method. The results indicate that the learned constitutive relation is quite consistent with the analytical one and the simulation results match well. In addition, predictive accuracy and time consumption are proven. Furthermore, to verify the applicability of the learned constitutive relation, the jet buckling case and the jet entering the static fluid case are modeled. The good performance demonstrates the ALSPH method has a promising prospect of applications in simulating complex flows in nature.