bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzymes of sphingolipid metabolism as transducers of metabolic inputs
Authors: Velazquez Fabiola N. , Luberto Chiara , Canals Daniel , Hannun Yusuf A.
Published: August 2024

Sphingolipids (SLs) constitute a discrete subdomain of metabolism, and they display both structural and signaling functions. Accumulating evidence also points to intimate connections between intermediary metabolism and SL metabolism. Given that many SLs exhibit bioactive properties (i.e. transduce signals), these raise the possibility that an important function of SLs is to relay information on metabolic changes into specific cell responses. This could occur at various levels. Some metabolites are incorporated into SLs, whereas others may initiate regulatory or signaling events that, in turn, modulate SL metabolism. In this review, we elaborate on the former as it represents a poorly appreciated aspect of SL metabolism, and we develop the hypothesis that the SL network is highly sensitive to several specific metabolic changes, focusing on amino acids (serine and alanine), various fatty acids, choline (and ethanolamine), and glucose.
A Review on Heat Transfer Performances of Thermosiphons Using Nanofluids
Authors: Ma Huiying , Cao Jiaokun , Sheng Qiang
Published: August 2024

Thermosiphon transfers heat by phase-change process. Nanofluid differs from traditional working medium. Nanofluids in thermosiphon can enhance heat transfer efficiency. Different kinds of nanofluids have different effects when used in thermosiphons. Thermosiphon with nanofluid as a working medium can be used in heat collection and cooling systems and has good working performance.
Construction of Co/CeO2 catalyst and study on catalytic performance
Authors: Li Long , Zhao Lifang , Li Yunyan , Wang Weiwen
Published: August 2024

High-temperature ammonia decomposition is a promising method for hydrogen production, but high temperatures and low conversion rates limit its wide application. In order to solve this problem, the development of nano-materials is essential to achieve high performance ammonia oxidation decomposition. In this paper, ordered mesoporous Co/CeO2 catalyst was synthesized by codeposition method and a new process of ammonia hydrogen production was developed and designed without the need for external heating. The catalyst was characterized by XRD, BET and TEM. The results show that the catalyst activity is the highest when Co content is 10wt%. When the molar ratio of NH3/O2 is 4:1, the bed temperature increases from 165°C to 405°C, the conversion rate of NH3 and O2 is 72% and 81%, respectively, and the productivity of H2 is 45%. The catalyst also showed good stability and reusability.
Research on aviation carbon reduction using aviation biofuels
Authors: Meng Yao , Liu Huahua , Xuan Jianqiang , Han Yan , Wen Fangyuan
Published: August 2024

In order to achieve sustainable aviation, countries are actively implementing actions to achieve plans to reduce the emissions of greenhouse gas and develop renewable energy. With the rapid development of the aviation industry, the impact of traditional aviation fuel combustion on climate change is significant, and the airline industry is facing severe challenges in reducing greenhouse gas emissions. Aviation biofuel is one of the promising alternative aviation fuels in the future. It has attracted increasing interest as it can effectively reduce greenhouse gas emissions as a clean and sustainable energy source. Various studies have been conducted to develop and evaluate biofuels. This report introduces the history and development of biofuels, discusses the preparation process, analyzes the greenhouse gas emission reduction effects, and discusses the prospects of aviation biofuels.
Analysis of uneven density of oil-based drilling fluid caused by shale respiration
Authors: Ni Xiaoxiao , Li Jian , Wang Jianhua , Yang Haijun , Liu Rentong , Shi He , Yan Lili , Gao Shan , Wang Xiaofei , Zhang Die
Published: August 2024

Longmaxi shale formation has developed beddings and fractures in southern Sichuan, which is prone to well leakage and wellbore instability. In the drilling process of horizontal section of Ning 209H58-2 well, drilling fluid would loss during circulation and return after pump stopped in the same section, which was the obviously respiration effect. The larger amount of leakage and pumping back, the greater the difference of drilling fluid density would be, accompanied by the increasing value of the gas. In this paper, shale was determined to have “screen effect” by assuming methods, the drilling fluid would loss as the equivalent circulating density was greater than the crack opening pressure, and the crack width was just in the size range of barite particle, then the larger size barite cannot enter in shale cracks end gathered together, and low density drilling fluid would penetrated into the formation, and then the drilling fluid density would be high in the first and low then after circulation again. The equivalent circulating density would be controlled by reducing the drilling fluid density, the effects of microfracture opening and respiration would be avoided, and the drilling fluid density would return to normal after circulation. This paper illustrates that the shale screen effect was the main reason for the uneven density of drilling fluid, which was expected to provide technical support for the development of horizontal shale gas Wells.
Quantifying the relative impacts of climate and human activities on vegetation change in Hunan Province between 2000 and 2015
Authors: Zhang Qingbin , Qi Cuicui , Wang Hui
Published: August 2024

Since1999, Hunan Province has embarked on a series of ecological projects to return farmland to forests across the province to explore the impacts of anthropogenic policies and actions on changes in vegetation cover between 2000 and 2015.It is important to understand the impacts of anthropogenic and climatic changes on regional vegetation cover change is an important guide for formulating reasonable environmental protection and restoration strategies in the region .this paper analysed the influence of climate and anthropogenic activities on the change of vegetation cover of Hunan Province during 2000-2015, which combined with an improved vegetation-climate residual regression model at the meta-scale. During 2000-2015, the contribution of anthropogenic activities to the increase of vegetation cover was 49%, 53%, 62% and 66% for unconverted forest land, grassland, unused land and water area respectively, while the contribution of climatic factors was 51%, 47%, 38% and 44% respectively. At the same time, all the land use types of contributions to vegetation cover change in Hunan Province is positive, and the land type without forest land change has the largest contribution to vegetation cover change in Hunan Province at 66.28%, while the land type where other land is converted to unused land has a lower contribution to vegetation cover change.
Programmable Droplet Manipulation on Superhydrophobic Surfaces with Charge Gradient
Authors: Xue Juncheng , Zhan Haiyang , Feng Shile
Published: August 2024

The controllable manipulation of droplets is pivotal for diverse applications spanning from microfluidics to biotechnology. In this paper, we present a novel droplet manipulation method leveraging a charge gradient on superhydrophobic surfaces. By shielding the charges on a superhydrophobic surface with uniform charges, a charge gradient is generated, which can drive a neutral droplet to move along the charge gradient. By controlling the motion trajectory of the metallic shield, a programmable droplet motion in a desired manner is achieved. This programmable droplet manipulation accompanied by non-contact, fast-responsive, ultrafast, and convenient performances is promising in many fluidic systems.
Research Progress of the Application of UV Light-Emitting Diodes for Water Disinfection
Authors: Wang Jinchi , Feng Xiaolin
Published: August 2024

With the increasing global demand for safe drinking water, the search for effective and economical water treatment technologies has become an urgent need. Ultraviolet (UV) light sterilization is a proven method for eliminating bacteria in water, but traditional UV systems often rely on mercury lamps, which pose potential environmental and health risks. In recent years, the development of UV-LED technology has offered a new solution for water treatment. This article provides a detailed explanation of the working principles, technological advantages, and applications of UV-LEDs in water treatment. By comparing them with traditional UV systems, UV-LEDs not only demonstrate lower energy consumption and longer lifespan, but also avoid the use of toxic mercury. Despite current challenges in cost and technological maturity, the environmental friendliness and efficiency potential of UV-LED technology indicate a promising market outlook. This article aims to provide a comprehensive review of UV-LED technology for practitioners and researchers in the water treatment industry, and to explore its future development directions.
Effect of Sterilization on the Change of Available Phosphorus During the Wetting and Drying Process
Authors: Jin Jiayao , Dai Gang
Published: August 2024

Wetting and drying are typical natural events in arid and semiarid areas. In order to explore the contribution of microorganisms to the change in soil phosphorus components during wetting and drying processes, soil incubation experiments were conducted on calcareous soil from Inner Mongolia grasslands. By comparing the change in various phosphorus fractions between sterilized and unsterilized soils, the microbial effect on the change in available phosphorus with soil moisture changes was studied. The results indicated that there was no significant difference in APi (NaHCO3-extractable inorganic phosphate) content between the two treatments. Sterilization caused the content of APo (NaHCO3-extractable inorganic phosphate) to significantly increase. These results suggested that soil microorganisms have a negligible influence on changes of soil available inorganic phosphorus (APi) in the present soil sample during the wetting and drying process. The change in APo may be related to the high-temperature and high-pressure sterilization processes. These results enrich our knowledge about the microbial influence on dynamics of soil available phosphorus during wetting and drying events.
A study of carbon cost pass-through rate differences in the power generation industry
Authors: Ma Tiannan , Yao Shiying , Ma Ruiguang , Wang Yun , Wang Qian , Zhang Jinrui , Zou Aimeng
Published: August 2024

In the context of the operation of China’s carbon emissions trading market, carbon cost pass-through will profoundly impact the country’s power generation industry. However, the core of studying carbon cost pass-through in the power generation industry is determining the carbon cost pass-through rate (CCPTR). Based on this, this paper first takes the Cournot model as the basic principle, which analyzes the impact of different power generation enterprises’ numbers and the characteristics of electricity market demand on the carbon pass-through results. Secondly, based on the Cournot model, this paper further CCPTR under marginal cost variability. The research results show that when the demand function is linear, the larger the CCPTR, the larger the proportion of carbon cost pass-through. When the demand function is isoelastic, the smaller the CCPTR, the smaller the proportion of carbon cost pass-through.
Psychodiagnostik in den psychosozialen Zentren für geflüchtete
Menschen
Authors: Pettrich Amelie , Nesterko Yuriy , Rimek Elisa , Glaesmer Heide
Published: August 2024

Ziel der Studie Eine sachgerechte Psychodiagnostik ist in der Behandlung
von Menschen mit psychischen Erkrankungen ein zentraler Schritt zur
Indikationsstellung und Qualitätssicherung. Über die psychodiagnostische Praxis
in der Versorgung Geflüchteter in den Psychosozialen Zentren (PSZ) unter
Bedingungen von Sprach- und Kulturbarrieren sowie Ressourcenknappheit ist wenig
bekannt. Die Studie zielt darauf ab, den Status Quo und
Entwicklungsmöglichkeiten für eine kultursensible Diagnostik in diesem Kontext
zu ermitteln.

Methodik Es wurde eine Onlinebefragung zur psychodiagnostischen Praxis, zu
Barrieren und zu wahrgenommenen Entwicklungspotentialen mit Vertretenden von 32
PSZ mithilfe eines selbstentwickelten Fragebogens durchgeführt und deskriptiv
ausgewertet.

Ergebnisse Die Mehrheit der Zentren zieht individuelle Fallklärungen der
standardisierten Diagnostik vor. Hauptgründe gegen die Nutzung standardisierter
Fragebögen und Interviews sind Schwierigkeiten bei der Vermittlung (fehlende
Vertrautheit mit Frageformaten, Lese- und Schreibschwierigkeiten) und fehlende
Ressourcen (Zeit, Übersetzungen). Bei der Durchführung der Diagnostik wird vor
allem der Zeitaufwand und die Priorisierung bei komplexen Fällen als
herausfordernd erlebt. Bedarf an weiteren Instrumenten besteht für mehrere
Störungsbilder und Sprachen. Mitarbeitende sind interessiert an Weiterbildungen
im Bereich der kultursensiblen Diagnostik.

Diskussion Die diagnostische Praxis in den PSZ ist durch zahlreiche
Herausforderungen geprägt, die sich von den Herausforderungen in der
Regelversorgung unterscheiden. Um eine angemessene standardisierte Diagnostik
und Versorgung für psychisch belastete Menschen mit Flucht- und
Migrationshintergrund zu gewährleisten, ist der weitere Ausbau der sprachlichen
und kulturellen Adaption sowie der psychometrischen Überprüfung etablierter
diagnostischer Instrumente unabdingbar.

Schlussfolgerung Auch in der Versorgung psychisch belasteter Geflüchteter
hat eine sachgerechte, kultursensible Diagnostik einen kritischen Mehrwert für
Behandler:innen und Betroffene. Auf vorhandene Ressourcen wird verwiesen.
Glucocorticoid Sensitivity Among Young Survivors of Childhood Acute
Lymphoblastic Leukemia: What Does It Matter?
Authors: Siviero-Miachon Adriana Aparecida , Lopes de Sousa Ana Virgínia , Simião Bruno Moreira , Araújo Elisangela Oliveira , Alvarenga Renato , Spinola-Castro Angela Maria , Longui Carlos Alberto
Published: August 2024

The aim of the study was to assess glucocorticoid sensitivity in survivors of
childhood acute lymphoblastic leukemia using in vivo and in vitro tests. Thirty
leukemia survivors of both sexes aged ≥18 years participated in the study and at
least two years after therapy withdrawal. In vivo tests comprised: a) a very low
dose intravenous dexamethasone suppression test for measurement of serum
cortisol before, after, and % suppression, compared with 32 age-matched
controls; and b) 0.25 mg overnight oral dexamethasone suppression test for
assessment of salivary cortisol before, after, and % suppression. In vitro
methods comprised: c) glucocorticoid receptor polymorphisms: BcI1-NR3C1 and
A3669G; and d) splicing variant of glucocorticoid receptor GR-α mRNA by
real-time quantitative polymerase chain reaction, compared with 32 controls.
There was a reduction in salivary cortisol, and 73.3% of leukemia survivors
showed high sensitivity according to % suppression after oral dexamethasone
(p<0.05). Serum cortisol at baseline, after the test, % suppression after
intravenous dexamethasone, and the percentage of high sensitivity were reduced
in the leukemia group (%F=36.7; p<0.05). The BcI1-NR3C1 and A3669G
polymorphisms were present in 11/30 (36.7%) and 5/30 (16.7%) patients,
respectively. GR-α mRNA levels were lower in the leukemia group than in the
controls (p<0.05). Survivors of acute lymphoblastic leukemia presented with
reduced glucocorticoid sensitivity. Glucocorticoid sensitivity allows
individualized treatment to avoid adverse effects and may be involved in
cardiovascular disease risk among this particular group of cancer survivors.
Lebensqualität im Langzeitverlauf nach prolongiertem Weaning in Abhängigkeit vom Weaning-Status
Authors: Schönhofer Bernd , Paul Andrea , Suchi Stefan , Zimmermann Maximilian , Stanzel Sarah Bettina , Windisch Wolfram , Berger Melanie
Published: August 2024

Einleitung Die Prognose von Patienten im prolongierten Weaning ist insbesondere in Abhängigkeit vom Weaning-Outcome eingeschränkt. Daten zur gesundheitsbezogenen Lebensqualität nach prolongiertem Weaning im Langzeitverlauf existieren bis heute jedoch nur spärlich.

Methodik Es wurde die gesundheitsbezogene Lebensqualität nach prolongiertem Weaning mittels SRI-Fragebogen erfasst (SRI = Severe Respiratory Insufficiency Questionnaire).

Ergebnisse Insgesamt haben 39 von 83 Patienten mit prolongiertem Weaning den SRI-Fragebogen ausgefüllt. Der zeitliche Abstand zur Entlassung aus dem Weaning-Zentrum betrug im Median 3,5 Jahre (IQR 2,4–4,5 Jahre). In der Gesamtgruppe lag der Median des Summenscores bei 56,4 (IQR 38,8–73,5). Patienten mit invasiver außerklinischer Beatmung (N=15) hatten eine deutliche schlechtere Lebensqualität im Summenscore als Patienten mit erfolgreicher Entwöhnung ohne Fortsetzung der maschinellen Beatmung (N=13) und solchen mit Fortsetzung einer nicht-invasiven Beatmung (N=11); Kruskal-Wallis-Test: H (2, N=39) = 7,875446; P=0,0195. Statistisch signifikante Unterschiede im Sinne einer schlechteren Lebensqualität bei Patienten mit invasiver außerklinischer Beatmung zeigten sich insbesondere auf den Subdomänen der sozialen Beziehungen (P=0,0325), der krankheitsbezogenen Ängste (P=0,0096) und des psychischen Befindens (P=0,0079).

Schlussfolgerung Patienten mit erfolglosem prolongierten Weaning und invasiver außerklinischer Langzeitbeatmung haben eine deutlich schlechtere gesundheitsbezogene Lebensqualität als Patienten mit erfolgreicher Entwöhnung vom Respirator. Weitere Studien mit höheren Fallzahlen sind notwendig, um weitere Einflussgrößen auf die gesundheitsbezogene Lebensqualität im prolongierten Weaning zu untersuchen.
The Efficacy and Safety of DOACs in Inherited Antithrombin Deficiency: A Cohort Study from a Tertiary Referral Center
Authors: Dix Caroline , Doyle Andrew J. , Breen Karen , Hunt Beverley J.
Published: August 2024

Background Individuals with inherited antithrombin deficiency (IATD) have a high risk of venous thromboembolism (VTE). Most VTEs are managed with direct oral anticoagulants (DOACs), but the utility of DOACs in antithrombin deficiency (ATD) is unreported.

Materials and Methods Patients with IATD treated with DOAC were identified from our institutions' IATD registry. We assessed patients' characteristics, ATD type, and initial VTE characteristics, thrombosis recurrence and bleeding rates.

Results Thirty-three patients received DOACs for 73 (38.5–111.5) months (median (interquartile range)). Prior to taking DOACs, 12 (36%) patients had VTE recurrence: these occurred after anticoagulation was ceased (4), nonadherence to VKA prior to DOAC use (3), or during heparin use in pregnancy (5). There were no VTE recurrences on standard-dose DOAC, except in a noncompliant patient receiving dabigatran. There was one recurrence with compliant DOAC use—a patient receiving rivaroxaban 10 mg. Six (18%) patients experienced clinically relevant bleeding, which was predominantly menorrhagia (5/6). One major bleeding event, intracranial hemorrhage, occurred in a patient receiving full-dose rivaroxaban who had refractory hypertension (0.5 events/100 patient-years). In this cohort, compliant DOAC users had an overall VTE recurrence rate of 0.5/100 patient-years, whereas with low-dose DOACs the event rate was 3.5/100 patient-years.

Conclusion Standard-dose DOACs appear efficacious and relatively safe in IATD.
Multiple Free Flaps and Second Toe Transfer to Salvage Grasp Function in Bilateral Complete Degloved Hands
Authors: Srikanth R. , Reddy D. Mukunda , Reddy K. Muralimohana , Rambabu N. , Kishore V. Ganga , Naidu Sandeep
Published: August 2024

A 21-year-old male laborer sustained bilateral degloving injury of the hands with multiple digital amputations and devascularized digits. After X-rays, preliminary debridement was done, when digital amputations were completed, including index ray amputation on both sides. The next day, two anterolateral thigh (ALT) flaps and one second toe transfer were done to restore coverage in the palm and the web and reconstruct the lost thumb. This ensured both coverage and thumb length on the right side, but on the left side the procedure was terminated with flap transfer only. After 3 months, the other second toe was harvested with a dorsalis pedis flap for reconstruction of the left thumb, and a free gracilis flap was done for optimal donor site coverage in the donor left foot. Evaluation after 2 years showed functional hands with reasonable power grasp, pinch grip, and dexterity to manipulate small and large objects that permitted an independent living.
The Impact of Double Pelvic Osteotomy on Dorsolateral Subluxation in 24 Dogs
Authors: Lomas Daniel C. , Cashmore Ricky , James Daniel , Jenkins Paul L.
Published: August 2024

Objective The aim of this study was to determine the effect of double pelvic osteotomy (DPO) on dorsolateral subluxation (DLS) of the femoral head in a weight-bearing position.

Study Design Retrospective observational study with treatment effect analysis. Twenty-four client-owned dogs that underwent DPO due to hip dysplasia.

Methods Computed tomography (CT) studies were performed on 24 dogs that underwent a DPO between 2015 and 2021. The patients were positioned with the femora in a weight-bearing position. The DLS score was measured pre-DPO, immediately post-DPO, and at follow-up to determine if DPO resulted in an increase in the DLS score.

Results A total of 21 dogs underwent single-stage bilateral DPO and 3 dogs underwent unilateral DPO resulting in 45 hip joints available for analysis. Follow-up CT was available for 29 of these at a median of 51 days (range: 35–482 days). The mean DLS score was 36.1% ± 14.6 preoperatively, 71.4% ± 12.5 post-DPO, and 70.0% ± 15.3 at follow-up. The increase between the pre- and postoperative measurement was significant (p < 0.001).

Conclusion DPO results in reduced subluxation of the femoral head in a weight-bearing position.

Clinical Significance The in vivo results suggest that DPO will result in reduced femoral subluxation during weight-bearing.
Biomechanical Comparison of Three Locking Compression Plate Constructs from Three Manufacturers under Cyclic Torsional Loading in a Fracture Gap Model
Authors: Lai Lik Hang , James Daniel Reynolds , Appleyard Richard Charles , Cadman Joseph
Published: August 2024

Objective The aim of the study was to compare the stiffness and cyclic fatigue of locking compression plate constructs from three manufacturers, DePuy Synthes (DPS), Knight Benedikt (KB), and Provet Veterinary Instrumentation (Vi), under cyclic torsion.

Methods The constructs of DPS, KB, and Vi were assembled by fixing a 10-hole 3.5-mm stainless steel locking compression plate 1 mm away from a validated bone model with a fracture gap of 47 mm. The corresponding drill guides and locking screws were used. Three groups of six constructs were tested in cyclic torsion until failure.

Results There was no significant difference in initial stiffness between DPS constructs (28.83 ± 0.84 N·m/rad) and KB constructs (28.38 ± 0.81 N·m/rad), and between KB constructs and Vi constructs (27.48 ± 0.37 N·m/rad), but the DPS constructs were significantly stiffer than the Vi constructs. The DPS constructs sustained the significantly highest number of cycles (24,833 ± 2,317 cycles) compared with KB constructs (16,167 ± 1,472 cycles) and Vi constructs (19,833 ± 4,792 cycles), but the difference between KB and Vi constructs was not significant. All constructs failed by screw damage at the shaft between the plate and the bone model.

Conclusion DPS constructs showed superior initial torsional stiffness and cyclic fatigue life than Vi constructs, whereas KB and Vi constructs shared comparable results. Further investigation is required to assess the clinical significance of these biomechanical differences.
Global asymptotic stability in a two-dimensional chemotaxis model arising from tumor invasion
Authors: Wu Chun
Published: August 2024

This paper considers the chemotaxis model with density-suppressed motility: ut = ∇·(φ(v)∇u) + ∇·(ψ(v)u∇v) + f(u), vt = Δv + wz, wt = −wz, wt = −wz, zt = Δz − z + u, x ∈ Ω, t > 0 under homogeneous Neumann boundary conditions in a smooth bounded domain Ω⊂R2. Given that the positive motility function φ(v) has the lower-upper bound, we can conclude that the system possesses a unique bounded classical solution. Moreover, it is proved that the global bounded solution (u, v, w, z) will converge to r/μ1α−1,v̄0+w̄0,0,r/μ1α−1 as t → ∞.
Rigidity on quantum symmetry for a certain class of graph C*-algebras
Authors: Karmakar Ujjal , Mandal Arnab
Published: August 2024

Quantum symmetry of graph C*-algebras has been studied, under the consideration of different formulations, in the past few years. It is already known that the compact quantum group (C(S1)∗C(S1)∗⋯∗C(S1)︸|E(Γ)|−times,Δ) [in short, *|E(Γ)|C(S1),Δ] always acts on a graph C*-algebra for a finite, connected, directed graph Γ in the category introduced by Joardar and Mandal, where |E(Γ)| ≔ number of edges in Γ. In this article, we show that for a certain class of graphs including Toeplitz algebra, quantum odd sphere, matrix algebra etc. the quantum symmetry of their associated graph C*-algebras remains *|E(Γ)|C(S1),Δ in the category as mentioned before. More precisely, if a finite, connected, directed graph Γ satisfies the following graph theoretic properties: (i) there does not exist any cycle of length ≥2 (ii) there exists a path of length (|V(Γ)| − 1) which consists all the vertices, where |V(Γ)| ≔ number of vertices in Γ (iii) given any two vertices (may not be distinct) there exists at most one edge joining them, then the universal object coincides with *|E(Γ)|C(S1),Δ. Furthermore, we have pointed out a few counter examples whenever the above assumptions are violated.
Wafer-bonded In0.53Ga0.47As/GaN p–n diodes with near-unity ideality factor
Authors: Sengupta Rohan , Little Brian , Mita Seiji , Markham Keith , Dycus J. Houston , Stein Shane , Wu Barry , Sitar Zlatko , Kish Fred , Pavlidis Spyridon
Published: August 2024

III–V/III-nitride p–n junctions were realized via crystal heterogeneous integration, and the resulting diodes were characterized to analyze electrical behavior and junction quality. p-type In0.53Ga0.47As, which is a well-established base layer in InP heterojunction bipolar transistor (HBT) technology, was used in combination with a homoepitaxial n-type GaN. The latter offers low dislocation density, coupled with high critical electric field and saturation velocity, which are attractive for use in future HBT collector layers. Transmission electron microscopy confirms an abrupt interface in the fabricated heterogeneous diodes. Electrical characterization of the diodes reveals a near-unity ideality factor (n ∼ 1.07) up to 145 °C, a high rectification ratio of ∼108, and a low interface trap density of 3.7 × 1012 cm−2.
Thin channel Ga2O3 MOSFET with 55 GHz fMAX and >100 V breakdown
Authors: Saha Chinmoy Nath , Vaidya Abhishek , Nipu Noor Jahan , Meng Lingyu , Yu Dong Su , Zhao Hongping , Singisetti Uttam
Published: August 2024

This Letter reports a highly scaled 90 nm gate length β-Ga2O3 (Ga2O3) T-gate MOSFET with a power gain cutoff frequency (fMAX) of 55 GHz. The 60 nm thin epitaxial Ga2O3 channel layer was grown by molecular beam epitaxy, while the highly doped (n++) source/drain regions were regrown using metal organic chemical vapor deposition. Maximum on current (IDS,MAX) of 160 mA/mm and trans-conductance (gm) around 36 mS/mm were measured at VDS = 10 V for LSD = 1.5 μm device. Transconductance and on current are limited by high channel sheet resistance (Rsheet). Gate/drain breakdown voltage of 125 V was measured for LGD = 1.2 μm. We extracted 27 GHz current gain cutoff frequency (fT) and 55 GHz fMAX for 20 V drain bias for unpassivated devices. While no current collapse was seen initially for both drain and gate lag measurements for 500 ns pulse, moderate current collapse was observed after DC, RF measurements caused by electrical stressing. We calculated a high fT. VBR product of 3.375 THz V, which is comparable to the state-of-the-art GaN HEMTs. This figure of merit suggests that Ga2O3 could be a potential candidate for X-band application.
On-state performance enhancement of AlGaN/GaN Fin-HEMTs by using arcuate sidewalls
Authors: Chen Yi-Lin , Zhu Qing , Zhang Meng , Mi Min-Han , Zhu Jie-Jie , Guo Si-Yin , Zhou Yu-Wei , Wang Peng-Fei , Gong Can , Zhao Zi-Yue , Ma Xiao-Hua
Published: August 2024

In this study, AlGaN/GaN Fin-HEMTs with different nanochannel geometric parameters were fabricated and comprehensively characterized. In the arcuate Fin-HEMTs, where the sidewalls arcuate from the source to the drain side, enhancements in the drain current density and transconductance were observed. By extracting and analyzing parameters obtained from small-signal measurements and conducting an analysis of gate capacitance, it was demonstrated that the enhancement can be attributed to the modulation of gate capacitance. This enhances the control capability of the gate over channel carriers, resulting in increased transconductance of the device. Due to the enhanced transconductance, the fT and fmax of the arcuate Fin-HEMTs are both enhanced. Notably, the arcuate Fin-HEMTs achieved a power-added efficiency of 71.4% at a frequency of 3.6 GHz and a drain voltage of 20 V. Meanwhile, the linearity of the arcuate Fin-HEMTs is improved compared with the conventional Fin-HEMTs.
Energy landscapes—Past, present, and future: A perspective
Authors: Schön J. C.
Published: August 2024

Energy landscapes and the closely related cost function landscapes have been recognized in science, mathematics, and various other fields such as economics as being highly useful paradigms and tools for the description and analysis of the properties of many systems, ranging from glasses, proteins, and abstract global optimization problems to business models. A multitude of algorithms for the exploration and exploitation of such landscapes have been developed over the past five decades in the various fields of applications, where many re-inventions but also much cross-fertilization have occurred. Twenty-five years ago, trying to increase the fruitful interactions between workers in different fields led to the creation of workshops and small conferences dedicated to the study of energy landscapes in general instead of only focusing on specific applications. In this perspective, I will present some history of the development of energy landscape studies and try to provide an outlook on in what directions the field might evolve in the future and what larger challenges are going to lie ahead, both from a conceptual and a practical point of view, with the main focus on applications of energy landscapes in chemistry and physics.
Shedding-scheme transition of hemisphere near wake dependent on Reynolds number
Authors: Tu Han , Wang Zhongyi , Gao Qi , She Wenxuan , Wang Fujun , Shi Zheyu , Wang Jinjun
Published: August 2024

The shedding-scheme transition of hemispherical wake is investigated with time-resolved tomographic particle image velocimetry. Experiments are carried out with Reynolds numbers based on the hemisphere radius R in the range of Rer=924–2315, crossing the critical value of Rer≈2000. The variation of the hemispherical wake across the critical Reynolds number is carefully studied, and a detailed mechanism of the shedding-scheme transition is explored. A singular-shedding pattern of hairpin vortices at a low Rer is replaced by a pairing-shedding pattern at a moderate Rer, and finally, a less ordered wake and an unstable shedding pattern are observed at Rer > 2000. The onset of the pairing-shedding pattern is due to a streamwise modulation caused by the varicose modes, which is related to the Kelvin–Helmholtz (K–H) instability. Consequently, the pseudo-periodicity induced by the K–H instability is observed in the wake. When Rer > 2000, the stronger sinuous modulation intensifies interactions among the hairpin vortices, leading to frequent absorption and annihilation of those coherent structures, which further makes the dominant frequency of main hairpin vortices halved downstream.
Quantitative investigation into the relationship between the fracture geometry and the well production during near-wellbore temporary plugging and diverting fracturing
Authors: Zhang Li , Yuan Lishan , Wang Bo , Zhou Hang , Zhou Fujian
Published: August 2024

During near-wellbore temporary plugging and diverting fracturing (NWTDF), the old fractures can be plugged, and the new fractures can be generated and propagated along the direction perpendicular to the old fractures. The fracture geometry after NWTDF determines the stimulated volume and the well productivity. Studying the quantitative relationship between fracture geometry and well production during NWTDF is of great significance for NWTDF optimization. Based on the large-scale true tri-axial fracturing equipment, this work carried out the fracture propagation experiments of NWTDF. The experiment results confirmed the feasibility of forming diversion fractures by plugging the old fractures. The extended finite element method obtained the overall fracture geometry under various conditions. Moreover, based on the propagation pattern of fracture geometries, a reservoir seepage model was established and applied to predict oil well production. The results show that: (1) The fracture diversion radius (FDR) significantly affects well production. When the diversion radius increases from 20 m to 110 m, the well production increases by 17.2%. (2) When the FDR increases from 20 m to 50 m, the area of the pressure sweep region increases by about 7.5%; when the FDR increases to 80 and 110 m, the degree of the area and the productivity uplift is not apparent. There is an optimal value of the FDR. (3) Well productivity significantly increases with diversion frequency, while when it reaches 9, the degree of the well productivity uplift is small. The diversion frequency should be optimized to obtain a desirable stimulated volume. The research results provide a theoretical basis for the optimization design of NWTDF.
Geometry optimization of wall-jet collection device: A study of flow-field dynamics and particle motion
Authors: Zhang Baiyuan , Zhao Guocheng , Xiao Longfei , Xu Lixin
Published: August 2024

Wall-jet collection has been recognized as an advanced technique for mining polymetallic nodules that has significant potential for practical engineering applications. Optimizing the geometry of the collection device can improve collection efficiency and reduce environmental disturbance. In this study, 24 distinct structures of nodule-collection device were investigated using a computational fluid dynamics–discrete element method, which was validated by comparing with the experimental data. A key parameter, the wall-jet half-width coefficient Cc, was employed to examine the collection performance, including the collection efficiency, collection flow field, and particle trajectory. An assessment indicator derived from energy-consumption and substrate-disturbance metrics was proposed, and this allowed the identification of optimal device structures tailored to various requirements. The results showed that based on collection efficiency–jet flow rate (η–q) response curves, the collection performance can be categorized into two distinct patterns. When Cc ≤ 1.56, induced flow will occur, and η can reach 1.0; when Cc > 1.56, a moving vortex that disturbs the particle trajectories is generated, and the jet escapes rightward, resulting in a decrease in η. The influences of geometric parameters on Cc exhibit coupled relationships, which is particularly noticeable in the relationship between the tangential angle of the jet and its thickness. The optimal device geometry varies for different criteria, and maximum reductions in substrate disturbance and jet energy consumption of 48.46% and 19.64%, respectively, were obtained with different optimization criteria. This study is expected to provide data to support the optimization of the structure of wall-jet collection devices.
Influence of O2 content on surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet to improve surface flashover strength
Authors: Wang Lijun , Zhao Huan , Liu Jie , Wang Yile
Published: August 2024

In order to improve the surface flashover strength of the insulation materials and solve the problem that the relatively high price of CF4 restricts the large-scale application of fluorination modification of CF4 atmospheric pressure plasma jet (APPJ) in the industrial field, He/CF4/O2 APPJ with different O2 content is used to treat epoxy resin (EP) dielectric material. By analyzing the results of scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy, the influence of O2 content on the multiple characteristics of EP surface before and after APPJ treatment is studied. Flashover experiment is also carried out on EP surface before and after APPJ treatment. It is found that the addition of 0.1% O2 can increase the mature voltage of the EP surface by about 16.10% compared with untreated EP surface. It is concluded that the improvement of the surface flashover strength with a small amount of O2 (within 0.1%) is influenced by the surface roughness and chemical composition of the dielectric. The deposition effect of APPJ on EP surface is enhanced to increase the surface roughness and reaches the best at 0.1% O2, because the addition of excessive O2 will weaken the APPJ intensity. It is speculated that the creepage distance of the EP surface is increased to inhibit the formation of electron collapse and the content of electronegative fluorine and oxygen on the EP surface is increased under a small amount of O2 addition, resulting in the inhibition of the formation of surface flashover.
A compact and portable gamma-ray spectrometer (GRASP) for inertial confinement fusion and basic science experiments
Authors: Dannhoff S. G. , Wink C. W. , Mackie S. , Berg G. P. A. , Frenje J. A.
Published: August 2024

A compact and portable gamma-ray spectrometer has been designed to diagnose different components of the inertial confinement fusion-relevant γ-ray spectrum with energies between ∼3.7–17.9 MeV. The system is designed to be as compact as possible for convenient transportation and fielding in diagnostic ports on the OMEGA laser, the National Ignition Facility, and other photon-source facilities. The system consists of a conversion foil for Compton scattering in front of four magnetic spectrometer “arms,” each covering a different energy range and constructed out of cylindrical permanent magnet Halbach arrays. Monte Carlo simulations have been used to optimize and assess the performance of the conversion foil, and COSY INFINITY ion-optical simulations have been used to optimize the spectrometer magnets. The performance of the design is assessed for a simulated direct-drive γ-ray spectrum. Spanning its total γ-ray energy bandwidth and using a 1.7 mm thick boron conversion foil, the system’s total energy resolution and efficiency are ∼15.8%–4.5% and 5.4 × 10−7–3.7 × 10−7e−/γ, respectively, with room for improvement. Spectral γ-ray measurements will provide guidance to the inertial confinement fusion program toward achieving high-energy gain relevant to inertial fusion energy and enable new measurement capabilities for basic discovery science.
A Q-band frequency tunable Doppler backscattering (DBS) system for pedestal and scrape-off layer density fluctuation and flow measurements in the DIII-D tokamak
Authors: Damba J. , Hong R. , Lantsov R. , Peebles W. A. , Rhodes T. L.
Published: August 2024

We present the design and laboratory tests for a new Q-band frequency tunable Doppler backscattering (DBS) system suitable for probing poloidal wavenumber kñ = 6–8 cm−1 density fluctuations and their flow velocities in the pedestal and scape-off layer (SOL) of the DIII-D tokamak. This system will provide new measurements in the increasingly important and under-diagnosed far pedestal and SOL plasma regions. These results are important for experimental transport studies and necessary for the validation of transport models, both of which are important to fusion energy research. The use of a single tunable frequency reduces the complexity and potential failure points as compared to a multichannel system. This new system utilizes a 33–50 GHz tunable source and will be integrated into the current V-band DBS in DIII-D using a broadband Q- and V-band multiplexer. A full-scale mockup of the quasi-optical system was used to test and optimize the performance. These tests include beam profile measurements at different distances (and angles) from a paraboloidal focusing and steering mirror. The measurements cover the full frequency range 33–75 GHz of the integrated/combined Q–V band DBS system and target a large radial coverage of the low-field side of the plasma from ρ = 1.1 to ρ = 0.5, where ρ is the normalized flux surface radial coordinate.
Large-eddy simulation of vortex-induced vibration of a circular cylinder at Reynolds number 10 000
Authors: Jiang Hongyi , Ju Xiaoying , Zhao Ming , Zhou Tongming , Draper Scott , An Hongwei , Watson Phil , Lei Zhenming , Wang Lizhong
Published: August 2024

The canonical scenario of cross-flow vortex-induced vibration (VIV) of a circular cylinder in the turbulent regime, which has been studied by several physical experiments in the literature, is reexamined in this study through high-fidelity large-eddy simulations (LES) at a Reynolds number 104. The VIV response (including vibration amplitude and frequency) and hydrodynamic coefficients predicted by the present LES agree with the experimental results better than previous numerical attempts. In addition, several phenomena reported by previous experimental studies are confirmed numerically for the first time. After validating against the experiments, new VIV characteristics and physical mechanisms are explored with confidence. First, a collective analysis on the frequency spectra of the displacement, lift, and velocity signals provides a complete picture of the frequency response of the system. In contrast, the use of a single signal may miss certain aspects of the frequency response, so that caution should be exercised. Second, spanwise correlation of primary vortex shedding is examined, where relatively low correlations in the upper and lower branches are likely because the vortex shedding patterns involve complex vortex generation and interaction. Third, the effect of mass ratio (m*) of the cylinder on the VIV response is analyzed with a range of m* (=1.4–3.4) relevant to cylindrical structures used in offshore engineering (such as subsea pipelines). The variations in the amplitude response, frequency response, and hydrodynamic coefficients with m* and reduced velocity are examined in detail. The present results suggest that a lighter pipeline is more susceptible to the onset of VIV.
Wettability step electrode to generate millimeter-scale gas–liquid interface for drag reduction
Authors: Zhang Mengzhuo , Hu Haibao , Ren Liuzhen , Wen Jun , Xie Luo
Published: August 2024

Superhydrophobic surfaces can seal the gas–liquid interface (GLI) under water to produce the drag reduction effect. Enhancing the stability and slip length of the GLI is an important issue in this context. Herein, we fabricate wettability step electrodes (WSEs) by creating an array of millimeter-scale circular superhydrophobic regions on a hydrophilic graphite plate by using an economical and efficient mask spraying method. When the WSE was electrified as an anode, the oxygen produced by the electrolytic reaction was preferentially precipitated in the superhydrophobic regions and ultimately formed an array of millimeter-scale GLIs. The evolution process of this GLI can be divided into a spreading stage and a growth stage. The results of experiments revealed that the spreading duration of the GLI increased with the diameter of the superhydrophobic regions (D) and decreased with the spacing between adjacent superhydrophobic regions (L). During the growth stage, the height of the GLI decreased with the ratio D/(L + D) and increased over the duration of electrification according to a 1/3 power-law relationship. Finally, we measured the slip characteristic on a single millimeter-scale GLI by particle image velocimetry. The result showed that the effective slip length of the GLI with a streamwise length of 2 mm can exceed 100 μm, thus confirming the potential of the millimeter-scale GLI for drag reduction.
The study of water wave scattering by series of submerged elastic scatterers
Authors: Mirza Tooba , -ul-Hassan Mahmood
Published: August 2024

A submerged flexible breakwater can be used to control waves in shallow water as an advanced alternative to traditional rigid submerged structures. Submerged flexible breakwaters not only cost less to build than conventional submerged breakwaters but also allow ships and marine life to bypass them if they are deep enough. These marine structures decrease the intensity of the shock wave and prevent standing waves from forming. We present a solution for transmission/reflection using a series of submerged identical elastic scatterers. Scattering and transfer matrices will be used to compute the transmission and reflection coefficients for N-submerged elastic scatterers. The behavior of the transmission for different values of physical parameters such as submergence depth, length of the scatterer, the gap between two successive scatterers, stiffness of the scatterer, and the number of submerged elastic scatterers is given. In doing so, we can achieve the frequencies and the incident amplitudes at which these submerged elastic scatterers can be effectively used as breakwaters in water of finite depth. We have looked at the transmission and reflection behaviors for a range of physical parameter values, such as the submergence depth, the length of the scatterer, the spacing between successive scatterers, the stiffness of the elastic scatterer, and the number of scatterers over a wide frequency range. We have given a spectrum of frequencies for which, given certain values of physical parameters, we can achieve zero transmission. Furthermore, even at high frequencies, we have demonstrated an incidence amplitude range for which zero propagation of transmission is feasible.
A study on the wake model of floating wind turbine with swaying motions based on an improved actuator disk method
Authors: Yang Jianghao , Liu Zhenqing , Hu Weicheng , Liu Shujie , Wang Nina
Published: August 2024

Offshore floating wind turbines may undergo swaying motions, resulting in significant changes in the wake wind field characteristics of the wind turbine, which can seriously affect the applicability and accuracy of existing wake models. This paper systematically investigates the turbulent wake flows of floating wind turbine with swaying motion based on an improved actuator disk method (ADM). The improved ADM is introduced to reproduce the wake flows of wind turbines, and the characteristics of the turbulent wind fields (i.e., mean wind velocity, turbulence intensity and Reynolds stress) are verified by wind tunnel tests. Furthermore, the wind fields of a floating wind turbine with different swaying amplitudes under turbulent atmospheric boundary layer are simulated, and the mean wind fields and turbulent statistics are analyzed. The performance of various existing wake models (i.e., Jensen model, modified Jensen model and Gaussian model) are compared, and a Gaussian-Shear wake model is proposed for floating wind turbines, which can account for non-uniform inflow and accommodate different swaying amplitudes. The results indicate that the proposed Gaussian-Shear wake model outperforms the other three models in describing the wake flows of floating wind turbines with swaying motions, which can be used for layout optimization and yaw control of offshore floating wind turbines.