bluuebunny/crossref_metadata_2025 huggingface dataset:
Additional 30-second observation of the right-sided colon for missed polyp detection with linked color imaging compared with narrow band imaging
Authors: Hashimoto Hikaru , Yoshida Naohisa , Inagaki Yoshikazu , Fukumoto Kohei , Hasegawa Daisuke , Okuda Kotaro , Tomie Akira , Yasuda Ritsu , Morimoto Yasutaka , Murakami Takaaki , Inada Yutaka , Tomita Yuri , Kobayashi Reo , Inoue Ken , Hirose Ryohei , Dohi Osamu , Itoh Yoshito
Published: August 2024

Background and study aims We previously demonstrated the efficacy of an additional-30-seconds (Add-30s) observation with linked color imaging (LCI) or narrow band imaging (NBI) of the cecum and ascending colon (right-sided colon) after white light imaging (WLI) observation for improving adenoma detection rate (ADR) by 3% to 10%. We herein compared Add-30s LCI with Add-30s NBI in a large number of cases.

Patients and methods We retrospectively collected 1023 and 1011 cases with Add-30s LCI and NBI observation for right-sided colon in 11 affiliated institutions from 2018 to 2022 and propensity score matching was performed. Add-30s observation was as follows. First observation: WLI observation of the right-sided colon as first observation. Second observation: Reobservation of right-sided colon by Add-30s LCI or NBI. The comparison of the mean numbers of adenoma+sessile serrated lesions (SSLs) and adenomas per patient (MASP and MUTYH-associated polyposis) were analyzed in the Add-30s LCI/NBI groups. The increase in right-sided ADR was also analyzed in the groups.

Results Among 748 matched cases in the Add-30s LCI/NBI groups, the MASP and MAP were 0.18/0.19 (P = 0.54) and 0.14/0.15 (P = 0.70). Among experts, they were 0.17/0.22 (P = 0.16) and 0.15/0.21 (P = 0.08). Among non-experts, they were 0.13/0.12 (P = 0.71) and 0.12/0.07 (P = 0.04). The right-sided ADRs of the first+second observations in the LCI and NBI groups were 32.2% and 28.9% (P = 0.16) and the increase of ADRs were 7.5% and 7.2% (P = 0.84).

Conclusions In right-sided colon, the detection of adenoma/SSL did not differ between Add-30s LCI and NBI. Both of them significantly increased ADR.
Borane-Catalyzed Divergent para and ortho C-Alkylation of Arylamines Using Benzylic Alcohols
Authors: Hu Hao-Lan , Chen Peng , Jiang Yi-Jun , Niu Yu-Dan , Li Meng-Yuan , Shi Jianghuan
Published: August 2024

A catalyst-controlled divergent alkylation of diarylamines with benzylic alcohols has been developed. A para C-alkylation of diarylamines could be achieved by using B(C6F5)3 as the catalyst, whereas ortho C-alkylation of diarylamines could be achieved by using HBF4·Et2O as the catalyst. The salient features of this transformation include readily available materials, a broad substrate scope, easily available catalysts, and simple and mild reaction conditions.
Nudging towards Sleep-Friendly Health Care: A Multifaceted Approach on Reducing Unnecessary Overnight Interventions
Authors: Kadura Sullafa , Eisner Lauren , Lopa Samia H. , Poulakis Alexander , Mesmer Hannah , Willnow Nicole , Pigeon Wilfred R.
Published: August 2024

Background Choice architecture refers to the design of decision environments, which can influence decision-making in health care. Nudges are subtle adjustments in these environments that guide decisions toward desired outcomes. For example, computerized provider order entry within electronic health records (EHRs) recommends frequencies for interventions such as nursing assessments and medication administrations, but these can link to around-the-clock schedules without clinical necessity.

Objectives This study aimed to evaluate an intervention to promote sleep-friendly practices by optimizing choice architecture and employing targeted nudges on inpatient order frequencies.

Methods We employed a quasi-experimental interrupted time series analysis of a multifaceted, multiphase intervention to reduce overnight interventions in a hospital system. Our intervention featured EHR modifications to optimize the scheduling of vital sign checks, neurological checks, and medication administrations. Additionally, we used targeted secure messaging reminders and education on an inpatient neurology unit (INU) to supplement the initiative.

Results Significant increases in sleep-friendly medication orders were observed at the academic medical center (AMC) and community hospital affiliate (CHA), particularly for acetaminophen and heparin at the AMC. This led to a reduction in overnight medication administrations, with the most substantial impact observed with heparin at all locations (CHA: 18%, AMC: 10%, INU: 10%, p < 0.05). Sleep-friendly vital sign orders increased significantly at all sites (AMC: 6.7%, CHA: 4.3%, INU: 14%, p < 0.05), and sleep-friendly neuro check orders increased significantly at the AMC (8.1%, p < 0.05). There was also a significant immediate reduction in overnight neurological checks performed at the AMC.

Discussion Tailoring EHR modifications and employing multifaceted nudging strategies emerged as promising approaches for reducing unnecessary overnight interventions. The observed shifts in sleep-friendly ordering translated into decreases in overnight interventions.

Conclusion Multifaceted nudges can effectively influence clinician decision-making and patient care. The varied impacts across nudge types and settings emphasizes the importance of thoughtful nudge design and understanding local workflows.
Embracing Robotics in Microsurgery: Robotic-Assisted Deep Inferior Epigastric Perforator Flap Breast Reconstruction
Authors: Choe Joshua , Aiello Christopher , Yom Jina , Minasian Raquel A. , Sugiyama Gainosuke , Smith Mark L. , Selber Jesse C. , Tanna Neil
Published: August 2024

The integration of robotic-assisted surgery (RAS) has transformed various surgical disciplines, including more recently plastic surgery. While RAS has gained acceptance in multiple specialties, its integration in plastic surgery has been gradual, challenging traditional open methods. Robotic-assisted deep inferior epigastric perforator (DIEP) flap breast reconstruction is a technique aimed at overcoming drawbacks associated with the traditional open DIEP flap approach. These limitations include a relatively large fascial incision length, potentially increasing rates of postoperative pain, abdominal bulge, hernia rates, and core weakening. The robotic-assisted DIEP flap technique emerges as an innovative and advantageous approach in fascial-sparing abdominal autologous breast reconstruction. While acknowledging certain challenges such as increased operative time, ongoing refinements are expected to further improve the overall surgical experience, optimize results, and solidify the role of robotics in advancing reconstructive microsurgical procedures in plastic surgery. Herein, the authors provide an overview of robotic surgery in the context of plastic surgery and its role in the DIEP flap harvest for breast reconstruction.
A Comparison of Postoperative Outcomes Based on Muscle versus Fasciocutaneous Flaps in Scalp Reconstruction: A Systematic Review and Meta-analysis
Authors: Stanton Eloise W. , Pekcan Asli , Roohani Idean , Choe Deborah , Carey Joseph N. , Daar David A.
Published: August 2024

Background Scalp reconstruction in plastic and reconstructive surgery often necessitates the transfer of soft-tissue flaps to restore form and function. The critical decision lies in choosing between muscle-containing (MC) and fasciocutaneous (FC) flaps for scalp reconstruction, and while both variants have their merits, flap composition remains a subject of ongoing debate. This scientific discussion aims to explore this contentious issue through a comprehensive meta-analysis, shedding light on the rationale behind the choice of these flaps and the potential impact on clinical outcomes.

Methods A comprehensive systematic review was conducted following PRISMA-P guidelines, encompassing six prominent databases up to the year 2023. Data were collected from studies assessing outcomes of MC and FC flaps for scalp reconstruction. Quality evaluation was performed using ASPS criteria and the ROBINS-I tool. Statistical analysis included descriptive statistics, meta-analysis, sensitivity analysis, and assessment of bias using STATA software.

Results The meta-analysis included 28 nonrandomized studies, totaling 594 flaps (MC: 380, FC: 214). MC flaps were significantly larger than FC flaps. There were no significant differences in flap loss, flap necrosis, or wound dehiscence between the two flap types. However, the incidence of venous congestion was significantly higher in FC flaps. Sensitivity analysis confirmed the robustness of results, and publication bias assessment showed no significant evidence of bias.

Conclusion While both MC and FC flaps offer viable options for scalp reconstruction, the choice should be tailored to individual patient characteristics and defect size. FC flaps may provide advantages such as shorter operative times and reduced morbidity, whereas MC flaps could be preferred for addressing larger defects. Future research should focus on prospective studies and strategies to mitigate venous congestion in FC flaps, enhancing their safety and efficacy in scalp reconstruction.
Angiosome-Guided Perfusion Decellularization of Fasciocutaneous Flaps
Authors: Yang Liya , Bai Xueshan , Liu Yuanbo , Zhu Shan , Li Shanshan , Chen Zixiang , Han Tinglu , Jin Shengyang , Zang Mengqing
Published: August 2024

Background Tissue engineering based on whole-organ perfusion decellularization has successfully generated small-animal organs, including the heart and limbs. Herein, we aimed to use angiosome-guided perfusion decellularization to develop an acellular fasciocutaneous flap matrix with an intact vascular network.

Methods Abdominal flaps of rats were harvested, and the vascular pedicle (iliac artery and vein) was dissected and injected with methylene blue to identify the angiosome region and determine the flap dimension for harvesting. To decellularize flaps, the iliac artery was perfused sequentially with 1% sodium dodecyl sulfate (SDS), deionized water, and 1% Triton-X100. Gross morphology, histology, and DNA quantity of flaps were then obtained. Flaps were also subjected to glycosaminoglycan (GAG) and hydroxyproline content assays and computed tomography angiography.

Results Histological assessment indicated that cellular content was completely removed in all flap layers following a 10-hour perfusion in SDS. DNA quantification confirmed 81% DNA removal. Based on biochemical assays, decellularized flaps had hydroxyproline content comparable with that of native flaps, although significantly fewer GAGs (p = 0.0019). Histology and computed tomography angiography illustrated the integrity and perfusability of the vascular system.

Conclusion The proposed angiosome-guided perfusion decellularization protocol could effectively remove cellular content from rat fasciocutaneous flaps and preserve the integrity of innate vascular networks.
Elevating Lower Extremity Reconstruction: An Algorithmic Approach to Free Flap Re-elevation
Authors: Nye Jessica R. , Mitchell David T. , Talanker Michael T. , Hopkins David C. , Wang Ellen , Obinero Chioma G. , Barrera Jose E. , Greives Matthew R. , Wu-Fienberg Yuewei , Bhadkamkar Mohin A.
Published: August 2024

Background Free flap (FF) reconstruction is frequently required for soft-tissue coverage after significant orthopaedic trauma of the lower extremity (LE). While usually the final step in limb salvage, re-elevation of the previously inset FF may be necessary to restore a functional limb. In this study, we present our algorithm for LE FF re-elevation and review our experience to identify factors associated with successful limb salvage and return to ambulation.

Methods A retrospective, single-institution review was conducted of adult patients with LE wounds who required FF reconstruction from 2016 to 2021. From this cohort, patients who required re-elevation of their LE FF were identified. Successful FF re-elevation was defined by limb salvage and return to ambulation.

Results During the study period, 412 patients with LE wounds required flap reconstruction. Of these patients, 205 (49.8%) underwent free tissue transfer, and 39 (9.5%) met our inclusion criteria. From this cohort, 34 had successful FF re-elevation, while 1 was non–weight bearing and 4 were elected for amputation due to chronic complications unrelated to their FF. Univariate analysis revealed the total number of FF re-elevations (p < 0.001), the frequency of re-elevation indicated for orthopaedic access (p < 0.001), and infections necessitating return to the operating room (p = 0.001) were each negatively associated with limb salvage and return to ambulation.

Conclusion The described algorithm highlights the preoperative planning and meticulous flap preservation necessary for the successful coverage of critical structures following FF re-elevation. Our data demonstrate that LE FFs can be safely re-elevated for hardware access or flap revision. In these complex cases of LE trauma, management by a multidisciplinary team is essential for successful limb salvage.
Impact of Resident and Attending Surgeon Training Level on Free Tissue Transfer Ischemia Time and Complications
Authors: Porter Brooke E. , Anderson Thalia C. , Ash Angela S. , Langsdon Sarah E. , Zelle Leanna M. , Willson Thomas D.
Published: August 2024

Background Microsurgical free tissue transfer has become an essential method for reconstruction of complex surgical defects, making the level of training an important factor to consider. There is little published regarding the impact of training level on microsurgical outcomes. This study investigates microsurgical free tissue transfer ischemia time and postoperative complications based on resident and attending surgeon experience level.

Methods A retrospective review of all free flaps at a single institution from January 1, 2013, to December 31, 2021 was performed. Linear regression was performed analyzing ischemia time of 497 free flaps and attending surgeon experience defined by years in practice and resident level defined as postgraduate year (PGY). Logistic regression model was used to analyze complications based on attending experience and resident level.

Results The average resident PGY was 3.5 ± 0.8; the average attending has been practicing for 6.4 ± 5.1 years. There was no statistically significant difference in ischemia time or complication rates based on resident PGY or attending surgeon experience level.

Conclusion Lower PGY residents were not found to increase ischemia time or increase complication rates. Lower attending surgeon year was not found to increase ischemia time or increase complication rates compared with surgeons who had been practicing for longer. Microsurgical free tissue transfer is considered a safe procedure in residency training and trainee involvement should be encouraged to improve resident education and enhance technical skills.
Hepatic Extracellular Matrix and Its Role in the Regulation of Liver Phenotype
Authors: Arteel Gavin E.
Published: August 2024

The hepatic extracellular matrix (ECM) is most accurately depicted as a dynamic compartment that comprises a diverse range of players that work bidirectionally with hepatic cells to regulate overall homeostasis. Although the classic meaning of the ECM referred to only proteins directly involved in generating the ECM structure, such as collagens, proteoglycans, and glycoproteins, the definition of the ECM is now broader and includes all components associated with this compartment. The ECM is critical in mediating phenotype at the cellular, organ, and even organismal levels. The purpose of this review is to summarize the prevailing mechanisms by which ECM mediates hepatic phenotype and discuss the potential or established role of this compartment in the response to hepatic injury in the context of steatotic liver disease.
Transabdominal Robotic Harvest of Bilateral DIEP Pedicles in Breast Reconstruction: Technique and Interdisciplinary Approach
Authors: Murariu Daniel , Chen Brian , Bailey Elizabeth , Nelson William , Fortunato Richard , Nosik Stanislav , Moreira Andrea
Published: August 2024

Background The deep inferior epigastric artery perforator (DIEP) flap is the gold standard for autologous breast reconstruction. However, the conventional procedure's anterior sheath division, from perforating vessels to the pedicle origin, risks weakening the abdominal wall's primary strength layer. Employing the da Vinci Xi Surgical System with indocyanine green dye and near-infrared fluorescence imaging, we refined a robotic technique for bilateral DIEP flap harvest. This approach enhances safety during vessel dissection, utilizing smaller fascial incisions. This study will present this technique in detail to microsurgeons interested in robotic DIEP flaps.

Methods In a retrospective cohort study spanning July 2021 to September 2022, female patients undergoing robotic bilateral DIEP flap reconstruction were analyzed. Following suprafascial flap dissection, the surgical robot was docked to target the pelvis, identifying and exposing deep inferior epigastric vessels intracorporeally. Mobilization and division occurred at their bases, with retrieval through a minimal anterior fascial incision, minimizing disruption to the abdominal wall and its motor innervation.

Results The study comprised 23 patients (46 flaps), with a mean fascial length of 4.1 cm and mean pedicle length of 12.82 cm. Mesh usage was absent. Robotic time averaged 139 minutes, overall case length was 739 minutes, and the average length of stay was 3.9 days. Notably, no pedicle or intra-abdominal injuries were reported.

Conclusion This technique ensures safe and efficient pedicle dissection in robotic DIEP flap harvests. Given the limited number of plastic surgeons adept in minimally invasive abdominal surgeries, we recommend collaborative efforts, with general surgeons initially assisting microsurgeons in adopting the robotic approach. This strategy facilitates a smooth transition until plastic surgeons attain confidence and competence in independent robotic dissection.
Platelets in Vascular Calcification: A Comprehensive Review of Platelet-Derived Extracellular Vesicles, Protein Interactions, Platelet Function Indices, and their Impact on Cellular Crosstalk
Authors: He Yi , Zhang Qiongyue , Pan Lina , Yang Hao , Liu Tao , Bei Junjie , Peter Karlheinz , Hu Houyuan
Published: August 2024

Vascular calcification (VC) commonly accompanies the development of atherosclerosis, defined by the accumulation of calcium in the arterial wall, potentially leading to stroke and myocardial infarction. Severe and unevenly distributed calcification poses challenges for interventional procedures, elevating the risks of vascular dissection, acute vascular occlusion, restenosis, and other major adverse cardiovascular events. Platelets promote the development of atherosclerosis by secreting various inflammatory mediators, regulating cell migration, aggregation, adhesion, and initiating and expanding inflammatory responses. There is emerging evidence that platelets play a direct role in VC; however, this novel concept has not yet been critically assessed. This review describes the intricate mechanisms by which platelets promote VC, focusing on three key aspects and the potential opportunities for their therapeutic targeting: extracellular vesicles, platelet-regulatory proteins, and indices related to platelet function.
Platelet-Type von Willebrand Disease: Complex Pathophysiology and Insights on Novel Therapeutic and Diagnostic Strategies
Authors: Fu Anne , Kazmirchuk Thomas D.D. , Bradbury-Jost Calvin , Golshani Ashkan , Othman Maha
Published: August 2024

von Willebrand disease (VWD) is the most common well-studied genetic bleeding disorder worldwide. Much less is known about platelet-type VWD (PT-VWD), a rare platelet function defect, and a “nonidentical” twin bleeding phenotype to type 2B VWD (2B-VWD). Rather than a defect in the von Willebrand factor (VWF) gene, PT-VWD is caused by a platelet GP1BA mutation leading to a hyperaffinity of the glycoprotein Ibα (GPIbα) platelet surface receptor for VWF, and thus increased platelet clearing and high-molecular-weight VWF multimer elimination. Nine GP1BA gene mutations are known. It is historically believed that this enhanced binding was enabled by the β-switch region of GPIbα adopting an extended β-hairpin form. Recent evidence suggests the pathological conformation that destabilizes the compact triangular form of the R-loop—the GPIbα protein's region for VWF binding. PT-VWD is often misdiagnosed as 2B-VWD, even the though distinction between the two is crucial for proper treatment, as the former requires platelet transfusions, while the latter requires VWF/FVIII concentrate administration. Nevertheless, these PT-VWD treatments remain unsatisfactory, owing to their high cost, low availability, risk of alloimmunity, and the need to carefully balance platelet administration. Antibodies such as 6B4 remain undependable as an alternative therapy due to their questionable efficacy and high costs for this purpose. On the other hand, synthetic peptide therapeutics developed with In-Silico Protein Synthesizer to disrupt the association between GPIbα and VWF show preliminary promise as a therapy based on in vitro experiments. Such peptides could serve as an effective diagnostic technology for discriminating between 2B-VWD and PT-VWD, or potentially all forms of VWD, based on their high specificity. This field is rapidly growing and the current review sheds light on the complex pathology and some novel potential therapeutic and diagnostic strategies.
Lived experiences of sexual minorities in their achievement of leadership and psychosocial well-being in organizational settings
Authors: Della Torre Renata , Pereira Henrique
Published: August 2024

The lack of studies on LGBTQIA+ people in leadership positions constitutes an investigative gap, which seems contradictory given that 7–15% of the population identifies with part of this community. The present study aimed to describe and explore the narratives of sexual minorities in leadership positions in Brazil and Portugal by comparing the two contexts and analyzing the psychological implications and well-being of this notably underrepresented population. To achieve that, a qualitative study was developed through an electronic interview, from which we obtained 45 participants, from which it was possible to identify 11 regular themes (LGBTQIA+ negativity, Health Impacts, LGBTQIA+ Identity, Impact of LGBTQIA+ identity on leadership, Intersectionality, Organizational Climate, Professional development, Personal characteristics, Social support, Coping strategies and Inspirational leadership). LGBTQIA+ negativity emerged as the most frequently mentioned theme. The results show that people still use avoidance mechanisms or counterfeit their LGBTQIA+ identity at work, while there are people who choose to have their LGBTQIA+ identity visible and use this as a tool to break heterosexist patterns, promoting equality and respect in the organizational environment through a queer leadership. It was possible to analyze the practices of leaders through the lens of queer theory, and we were able to observe that sexual minorities in Portugal and Brazil are united not only by language but also by similar experiences marked by discrimination and challenges, generating a major psychological impact. Despite these difficulties, these leaders tend to use their personal principles, showing characteristics of authentic leadership.
Dynamical system identification, model selection, and model uncertainty quantification by Bayesian inference
Authors: Niven Robert K. , Cordier Laurent , Mohammad-Djafari Ali , Abel Markus , Quade Markus
Published: August 2024

This study presents a Bayesian maximum a posteriori (MAP) framework for dynamical system identification from time-series data. This is shown to be equivalent to a generalized Tikhonov regularization, providing a rational justification for the choice of the residual and regularization terms, respectively, from the negative logarithms of the likelihood and prior distributions. In addition to the estimation of model coefficients, the Bayesian interpretation gives access to the full apparatus for Bayesian inference, including the ranking of models, the quantification of model uncertainties, and the estimation of unknown (nuisance) hyperparameters. Two Bayesian algorithms, joint MAP and variational Bayesian approximation, are compared to the least absolute shrinkage and selection operator (LASSO), ridge regression, and the sparse identification of nonlinear dynamics (SINDy) algorithms for sparse regression by application to several dynamical systems with added Gaussian or Laplace noise. For multivariate Gaussian likelihood and prior distributions, the Bayesian formulation gives Gaussian posterior and evidence distributions, in which the numerator terms can be expressed in terms of the Mahalanobis distance or “Gaussian norm” ||y−y^||M−12=(y−y^)⊤M−1(y−y^), where y is a vector variable, y^ is its estimator, and M is the covariance matrix. The posterior Gaussian norm is shown to provide a robust metric for quantitative model selection for the different systems and noise models examined.
Understanding the role of B cells in CAR T-cell therapy in leukemia through a mathematical model
Authors: Serrano Sergio , Barrio Roberto , Martínez-Rubio Álvaro , Belmonte-Beitia Juan , Pérez-García Víctor M.
Published: August 2024

Chimeric antigen receptor T (CAR T) cell therapy has been proven to be successful against a variety of leukemias and lymphomas. This paper undertakes an analytical and numerical study of a mathematical model describing the competition of CAR T, leukemia, tumor, and B cells. Considering its significance in sustaining anti-CD19 CAR T-cell stimulation, a B-cell source term is integrated into the model. Through stability and bifurcation analyses, the potential for tumor eradication, contingent on the continuous influx of B cells, has been revealed, showing a transcritical bifurcation at a critical B-cell input. Additionally, an almost heteroclinic cycle between equilibrium points is identified, providing a theoretical basis for understanding disease relapse. Analyzing the oscillatory behavior of the system, the time-dependent dynamics of CAR T cells and leukemic cells can be approximated, shedding light on the impact of initial tumor burden on therapeutic outcomes. In conclusion, the study provides insights into CAR T-cell therapy dynamics for acute lymphoblastic leukemias, offering a theoretical foundation for clinical observations and suggesting avenues for future immunotherapy modeling research.
Investigation of interface traps in β-(AlGa)2O3/Ga2O3 heterostructures by dynamic capacitance dispersion technique
Authors: Florena Fenfen Fenda , Traoré Aboulaye , Okumura Hironori , Morita Ryo , Jia Yun , Sakurai Takeaki
Published: August 2024

In this work, interface traps in β-(AlGa)2O3/Ga2O3 modulation-doped field effect transistor (MODFET) were investigated qualitatively and quantitatively by means of dynamic capacitance dispersion technique. The fabricated β-(AlGa)2O3/Ga2O3 MODFET showed drain current modulation demonstrating the transistor behavior. The existence of two-dimensional electron gas was confirmed by the plateau region in the capacitance–voltage (C–V) characteristics. The difference in capacitance profile dispersion at multifrequency C–V measurement suggested the loss mechanism due to trapping and de-trapping effects of carriers. An interface analysis of β-(AlGa)2O3/Ga2O3 heterostructures estimated the interface states with density of trap states and time constants of 0.56×1012–5.92×1012 cm−2 eV−1 and 59–27 μs, respectively.
On the reduction of gas permeation through the glass windows of micromachined vapor cells using Al2O3 coatings
Authors: Carlé C. , Mursa A. , Karvinen P. , Keshavarzi S. , Abdel Hafiz M. , Maurice V. , Boudot R. , Passilly N.
Published: August 2024

Stability and precision of atomic devices are closely tied to the quality and stability of the internal atmosphere of the atomic vapor cells on which they rely. Such an atmosphere can be stabilized by building the cell with low permeation materials such as sapphire or aluminosilicate glass in microfabricated devices. Recently, we have shown that permeation barriers made of Al2O3 thin-film coatings deposited on standard borosilicate glass could be an alternative for buffer gas pressure stabilization. In this study, we, hence, investigate how helium permeation is influenced by the thickness, ranging from 5 to 40 nm, of such Al2O3 thin films coated by atomic layer deposition. Permeation rates are derived from long-term measurements of the pressure-shifted transition frequency of a coherent population trapping (CPT) atomic clock. From thicknesses of 20 nm onward, a significant enhancement of the cell hermeticity is experienced, corresponding to two orders of magnitude lower helium permeation rate. In addition, we test cesium vapor cells filled with neon as a buffer gas and whose windows are coated with 20 nm of Al2O3. As for helium, the permeation rate of neon is significantly reduced, thanks to alumina coatings, leading to a fractional frequency stability of 4×10−12 at 1 day when the cell is used in a CPT clock. These features outperform the typical performances of uncoated Cs–Ne borosilicate cells and highlight the significance of Al2O3 coatings for buffer gas pressure stabilization.
A comprehensive electron wavefunction analysis toolbox for chemists, Multiwfn
Authors: Lu Tian
Published: August 2024

Analysis of electron wavefunction is a key component of quantum chemistry investigations and is indispensable for the practical research of many chemical problems. After more than ten years of active development, the wavefunction analysis program Multiwfn has accumulated very rich functions, and its application scope has covered numerous aspects of theoretical chemical research, including charge distribution, chemical bond, electron localization and delocalization, aromaticity, intramolecular and intermolecular interactions, electronic excitation, and response property. This article systematically introduces the features and functions of the latest version of Multiwfn and provides many representative examples. Through this article, readers will be able to fully understand the characteristics and recognize the unique value of Multiwfn. The source code and precompiled executable files of Multiwfn, as well as the manual containing a detailed introduction to theoretical backgrounds and very rich tutorials, can all be downloaded for free from the Multiwfn website (http://sobereva.com/multiwfn).
Characterization of similar Marshak waves observed at the LMJ
Authors: Courtois C. , Gisbert R. , Botrel R. , Chaleil A. , Chopineau L. , Debesset S. , Fariaut J. , Henry O. , Le Déroff L. , Loupias B. , Rousseau A. , Soullie G. , Villette B.
Published: August 2024

We detail results of two experiments performed at the Laser Mégajoule (LMJ) facility aimed at studying similar supersonic Marshak waves propagating in a low-density SiO2 aerogel enclosed in metallic tubes. Similar means here that these two experiments, driven by the same input radiation temperature history, use purposely very different tubes in terms of length (L = 1200 or 2000 μm), diameter (2R = 1000 or 2000 μm), nature of the wall (gold or copper), and aerogel densities (ρ = 30 or 20 mg/cm3), yet the transit time and the radiation temperature of the fronts at the tube exit are the same for both shots. Marshak waves are characterized at the exit using simultaneously for the first time to our knowledge, a one dimensional soft x-ray imager from which the radiation front transit time and curvature are measured and also a broadband x-ray spectrometer to infer its temperature history. These constraining results are then successfully compared to those from simple analytical models [Cohen et al., Phys. Rev. Res. 2, 023007 (2020) and Hurricane et al., Phys. Plasmas 13, 113303 (2006)] and from the three dimensional Lagrangian radiation-hydrodynamics code TROLL to get information on x-ray energy losses. Controlled compensation effects between the length, diameter, and nature of the tubes (governing these losses) are such that the radiation temperature drop along the tubes is eventually the same for these two similar shots.
Multipactor analysis of 431 MHz L-shaped inductive output tube cavity
Authors: Nadeem Muhammad Khawar , Wang Shaomeng , Jameel Atif , Ali Bilawal , Latif Jibran , Gong Yubin
Published: August 2024

Gridless inductive output tubes (IOTs) offer compact size and high-power amplification at sub-GHz frequencies. Minimizing cavity dimensions in the interest of compactness leads to smaller gaps, which may cause multipactor discharge under high-power operating conditions. The uncontrolled electron growth resulting from multipactor breakdown can lead to undesired effects including surface damage and system failure. This paper performs a parallel-plate multipactor analysis for a high-Q, L-shaped, aluminum, 431 MHz cavity designed for a gridless IOT to be operated in the MW-power regime. The cavity gap is 27 mm, and diameter is 339 mm. Multipactor susceptibility regions are calculated for non-zero emission energy, half-cycle, and non-half-cycle multipactor using a semi-analytic approach and a standard aluminum secondary electron yield (SEY) curve. The analytical results are validated with particle-in-cell simulation in CST Studio. Simulation results show a voltage range of 6.4–19 kV, compared to the analytically calculated values of 8.2 and 18.3 kV for the lower and upper bounds, respectively. Fluorocarbon coating as a means to reduce secondary electron emission is simulated, which shows 46% reduction in peak particle population with an 11.2 nm PTFE coating, with further reduction as coating thickness increases. The results show that the L-shaped cavity is a suitable choice for this IOT design as it does not exhibit single-surface multipactor and will not develop two-surface multipactor at full-power operation.
Direct numerical simulation of laminar boundary layer interaction with a wall-mounted circular cylinder at low-Reynolds number
Authors: Asgari Ehsan , Saeedi Mohammad
Published: August 2024

In our current study, we employ direct numerical simulation to investigate the interaction between a laminar boundary layer flow and a wall-mounted circular cylinder with an aspect ratio of 4 and a Reynolds number of 750, based on the cylinder diameter and free-stream velocity. As highlighted in recent works by Morton et al. [Int. J. Heat Fluid Flow 72, 109–122 (2018)] and Crane et al. [J. Fluid Mech. 931, R1 (2022)], understanding of flow at low-Reynolds number around wall-mounted circular cylinders remains limited, motivating our study to contribute to this knowledge gap. Our objectives include exploring flow topology, analyzing first- and second-order statistics to characterize the turbulent wake flow, and investigate turbulent kinetic energy transport budgets to comprehend energy transfer mechanisms behind the cylinder. Our spectral analysis of velocity content reveals a low-frequency peak, consistent with recently published literature. However, we observe certain discrepancies between our findings and those of similar studies conducted at lower Reynolds numbers, particularly regarding the frequency content of the wake region. We employ dynamic mode decomposition to unravel the flow dynamics associated with the highest-amplitude mode. Our results indicate that the low-frequency mode reported in the above-mentioned references primarily correlates with the incoming boundary layer and is prominently evident in the lateral force coefficient, in contrast to scenarios at higher Reynolds numbers.
Advanced ultrasound techniques for studying liquid–liquid dispersions in confined impinging jets
Authors: Hossein Fria , Duan Cong , Angeli Panagiota
Published: August 2024

Advanced ultrasound techniques were used to study liquid–liquid dispersed flows formed in impinging jets confined in small channels. Ultrasound speed and attenuation coefficient spectra of the propagated sound waves were used to obtain volume fraction and drop size distributions, respectively. The results were compared against drop size distributions obtained with high-speed imaging. Experiments were conducted in a 2 mm internal diameter tube for both kerosene oil continuous and glycerol/water continuous dispersions. The overall mixture flow rate was set at 60 ml/s, and the dispersed phase fractions were 0.02, 0.05, and 0.10. The measured volume fractions were found to be very close to the input ones, indicating a very small slip between the phases in the dispersed flows. From the ultrasound measurements, the drop size distributions were found to range from 32 to 695 μm under the different conditions used. The drop sizes at the two low input volume fractions were in reasonable agreement with the results from the imaging. Imaging, however, could not be used for the 0.10 input dispersed phase fraction. These results demonstrate the applicability of the ultrasound techniques to measurements in dispersed liquid–liquid flows in small channels.
Three-dimensional trajectories of irregular-shaped tunnel lining fragments in the flow environment caused by high-speed trains
Authors: He Hong , Yang Wei-Chao , Liu Yi-Kang , Deng E.
Published: August 2024

High-speed railway tunnel lining fragments can cause collisions with trains and track blockages, severely affecting train operation. When a train passes through a tunnel where lining fragment is likely to occur, the train wind effect may significantly affect the trajectory of the lining fragment, making the location where the lining fragment is difficult to predict. For safety purpose, this study aims to analyze the impact of the initial circumferential position and shape of irregular-shaped lining fragments on their aerodynamic performance. Using on-site scanning and mathematical statistical methods, the shape characteristics and probability distribution of actual lining fragments in the tunnel are obtained. The aerodynamic behavior of irregular-shaped lining fragments with different initial positions and three typical aspect ratios (ARs) are investigated based on the overset grid method and the dynamic fluid–body interaction model framework as a high-speed train passes. The study found that the most representative lining fragments with an AR of three have a mass of 1.5 kg and are located 2.5 m from the tunnel centerline. The flight behavior of lining fragments shows distinct three-dimensional features, with both translation and rotation significantly affected by the aerodynamic effects of the train and the geometric shape of the fragments. The longitudinal and lateral translational distances of lining fragments at the top of the train decrease as their initial position moves further from the tunnel's centerline. With an increase in AR, both the longitudinal and lateral flight distances and average flight velocities of the fragments increase. The macroscopic flow field within the tunnel directly influences the motion characteristics of the lining fragments. Complex flow separation and circulation phenomena near the fragments result in uneven pressure differences acting on the smooth and rough surfaces of the lining fragments, causing irregular motion. The conclusions of this study provide a theoretical basis for assessing and preventing the impact of lining fragments on the operational safety of trains.
Symmetry breaking of rotating convection due to non-Oberbeck–Boussinesq effects
Authors: Wang Shuang , Kang Wanying
Published: August 2024

The non-Oberbeck–Boussinesq (NOB) effects arising from variations in thermal expansivity are theoretically and numerically studied in the context of rotating Rayleigh–Bénard convection in forms of two-dimensional rolls. The thermal expansivity increases with pressure (depth), and its variation is measured by a dimensionless factor ε. Utilizing an asymptotic expansion with weak nonlinearity, we derive an amplitude equation, revealing that NOB effects amplify the magnitude of convection. An ε2-order NOB correction leads to a symmetry breaking about the horizontal mid-plane, manifested in the strengthening of convection near the bottom and its weakening near the top, forming bottom-heavy profiles. At ε3-order, the conjunction of NOB effects and nonlinear advection leads to a horizontal symmetry breaking. The values of Taylor number and Prandtl number determine whether upward or downward plumes are stronger. Numerical calculations validate the theoretical analyses in weakly nonlinear regime. This work advances our understanding of hydrothermal plumes in some winter lakes on Earth and in the subglacial oceans on icy moons as well as tracer transport from the seafloor to the ice shell.
Preparation and loss analysis of Ge on Si SWIR optical strip waveguides
Authors: Wang Xiaoyu , Cong Hui , Xie Changjiang , Li Yue , Xu Guoyin , Wang Yixin , Xu Chi , Xue Chunlai
Published: August 2024

On-chip integrated photonics with operating wavelength at short-wave infrared region is becoming popular for its potential advantages in extending the telecommunication bandwidth and the application in gas sensing. As an important component of integrated optoelectronic chips, high-performance waveguides have attracted widespread attention. In this work, high-performance Ge waveguides were designed and fabricated on the Ge-on-Si platform, in which germanium films were epitaxially grown by the chemical vapor deposition process. The propagation loss for the waveguide was measured to be 2.34 dB/cm at the wavelength of 2 μm through the cut-back method. The quantitative relationship between the waveguide propagation loss and sidewall roughness as well as material defect density was established by introducing an empirical coefficient m. The m value was calculated to be 3.8 × 10−4 dB for the waveguide with a fixed Ge thickness of 1.5 μm by fitting the experimental propagation loss data at an operating wavelength of 2 μm. This formula provides a significant reference for future design of waveguide dimension structures, where defect induced absorption loss is non-negligible.
Novel mixed approximate deconvolution subgrid-scale models for large-eddy simulation
Authors: Amani Ehsan , Molaei Mohammad Bagher , Ghorbani Morteza
Published: August 2024

Approximate deconvolution (AD) has emerged as a promising closure for large-eddy simulation in complex multi-physics flows, where the conventional pure dynamic eddy-viscosity (DEV) models experience issues. In this research, we propose novel improved mixed hard-deconvolution or secondary-regularization models and compare their performance with the existing standard mixed AD-DEV and penalty-term regularizations. For this aim, five consistency criteria, based on the properties of the modeled sub-filter-scale stress in limiting conditions, are introduced for the first time. It is proved that the conventional hard-deconvolution models do not adhere to a couple of important primary criteria. Furthermore, through a priori and a posteriori analyses of Burgers turbulence and turbulent channel flow, it is manifested that the inconsistency with the primary criteria can result in larger modeling errors, the over-prediction and pileup of kinetic energy in eddies of a length scale between the explicit filter width and grid size, and even the solution instability. On the other hand, the favorable characteristics of the new mixed models, in terms of the consistency criteria, significantly improve the accuracy of the predictions, the solution stability, and even the computational cost, particularly for one of the new models called mixed alternative-DEV (A-DEV).
Vortex-induced vibration of a rotating cylinder with dual splitter plates
Authors: Du Aoyue , Chen Wei , Lin Yongshui , Chi Qingjia , Rheem Chang-Kyu , Wen Binrong , Liu Zailiang , Li Xiaobin
Published: August 2024

To explore suppression method on vortex-induced vibrations (VIVs) response of the rotating cylinders, the VIVs of two-degree-of-freedom rotating cylinders with dual splitter plates at a Reynolds number of 200 and a mass ratio of 2.6 are investigated via numerical simulations. The numerical results show that splitter plates are more effective at suppressing VIV in the cylinders with low rotation rates, and the suppression effect decreases with increasing rotation rate. Three flow patterns are defined [overshoot, merge shedding, and individual shedding], and the distributions of the flow patterns and wake patterns under different rotation rates and gap distances are discussed. The vibration–fluid force–wake interaction is analyzed, and the variation of flow patterns is accompanied by the sudden increase in amplitude and fluid force. In addition, the directional sensitivity of the lift and drag is discussed, the lift is more sensitive to the rotation rate, and the drag is more sensitive to the gap distance.
Rayleigh–Taylor mixing in porous media at an extreme viscosity contrast
Authors: Mohammadi Mohammadjavad , Bagherzadeh Hadi , Nath Devjyoti , Bin Dahbag Mabkhot , Hassanzadeh Hassan
Published: August 2024

We present experimental findings of Rayleigh–Taylor (RT) instability within porous materials, with a significant viscosity contrast of M ≈ 106, where M represents the ratio of the dynamic viscosity of heavy fluid to that of light fluid, M = μH/μL, and Ra = 6.62 × 104–6.67 × 105, and Rayleigh number (Ra) quantifies the relative significance of buoyancy forces compared to viscous forces. We observe that the lighter fluid diffuses into the denser one, creating a transient diffusive boundary layer that rapidly becomes unstable, transitioning into a convection-dominated regime. Initially, the instability manifests as small fingers protruding upward. However, these fingers coalesce and form fewer major fingers. Convection persists until fingers reach the upper boundary, transitioning into a shutdown regime. During the convection-dominated phase, the extracted solute concentration exhibits a linear relationship with time on a log –log scale, suggesting a constant mass flux. However, this flux diminishes upon entering the shutdown regime. The steady flux, quantified by the Sherwood number, correlates with the Rayleigh number as Sh = 0.046Ra, indicating independence from the height of the porous medium. We have also developed a simple conceptual model that effectively captures the dynamics of RT mixing.
Experimental investigation of capillary pressure diagram in oil/water transition zone of low-permeability reservoirs
Authors: Ma Min , Li Aifen , Fan Dongyan , Fu Shuaishi , Sun Hai , Zhang Lei , Yao Jun
Published: August 2024

The oil/water transition zone, particularly pronounced in low-permeability formations with small pore diameters and high capillary pressure, contains a substantial portion of original oil in place. The capillary pressure curves provide essential data for the calculation of the original oil in place as well as the oilfield development simulation. However, the traditional single capillary pressure curve cannot provide enough information. To address this challenge, an experimental investigation was conducted to explore the capillary pressure diagrams within the oil/water transition zone of low-permeability reservoirs. The results shed light on the complex behavior of capillary pressure, the influence of initial water saturation, and the relationship between initial oil saturation and residual oil saturation. Incorporating the behavior of capillary pressure into reservoir simulation models can enhance reservoir characterization and improve the accuracy of oil production performance in low-permeability reservoirs.