bluuebunny/crossref_metadata_2025 huggingface dataset:
The importance of muscle glycogen phosphorylase in glial cells function
Authors: Llavero Francisco , Zugaza José L.
Published: April 2024

The three isoforms of glycogen phosphorylase — PYGM, PYGB, and PYGL — are expressed in glial cells. Unlike PYGB and PYGL, PYGM is the only isoform regulated by Rac1. This specific regulation may confer a differential functional role compared with the other glycogen phosphorylases-PYGB and PYGL. The involvement of muscle glycogen phosphorylase in glial cells and its association with post-translational modifications (PTMs) of proteins through O-glycosylation is indeed a fascinating and emerging area of research. The dual role it plays in metabolic processes and the regulation of PTMs within the brain presents intriguing implications for various neurological conditions. Disruptions in the O-GlcNAcylation cycle and neurodegenerative diseases like Alzheimer's disease (AD) is particularly noteworthy. The alterations in O-GlcNAcylation levels of specific proteins, such as APP, c-Fos, and tau protein, highlight the intricate relationship between PTMs and AD. Understanding these processes and the regulatory function of muscle glycogen phosphorylase sheds light on its impact on protein function, signaling pathways, cellular homeostasis, neurological health, and potential interventions for brain-related conditions.
Acoustic Analyses of Tone Productions in Sequencing Contexts Among Cantonese-Speaking Preschool Children With and Without Childhood Apraxia of Speech
Authors: Wong Eddy C. H. , Wong Min Ney , Velleman Shelley L.
Published: April 2024

Purpose:

Pitch variations (tone productions) have been reported as a measure to differentiate Cantonese-speaking children with and without childhood apraxia of speech (CAS). This study aims to examine fundamental frequency (
F
0) changes within syllables and the effects of syllable structure, lexical status, and syllable positions on
F
0 in Cantonese-speaking preschool children with and without CAS.

Method:

Six children with CAS, six children with non-CAS speech sound disorder plus language disorder (S&LD), 22 children with speech sound disorder only (SSD), and 63 children with typical speech-language development (TD) performed the tone sequencing task (TST). Growth curve analysis was employed to analyze and compare the
F
0 values within syllables with three Cantonese tones (high level, high rising, and low falling). The analysis considered the effects of syllable structure (vowel and consonant–vowel), lexical status (word and nonword), and syllable position (initial, medial, and final) on
F
0, as well as comparisons within and between groups.

Results:

Within each group, the effects of syllable structure and position on
F
0 values were found with different patterns. Between-group comparisons showed that the CAS group had reduced
F
0 contrasts. The CAS group could be differentiated from the control groups based on interactions of
F
0 with syllable structure and position, but not lexical status. The dissimilarity of
F
0 values detected between the CAS and SSD/TD groups was more prominent than that observed between the CAS and S&LD groups.

Conclusions:

This study demonstrated that Cantonese-speaking children with CAS had difficulty in varying
F
0 within syllables as compared to those without CAS, suggesting pitch variation difficulty and language-specific impairment profiles in CAS. Future investigations of objective measures for identifying Cantonese speakers with CAS and cross-linguistic investigations using growth curve analysis and the TST are suggested.
Space classification for indoor pedestrian navigation with morphological and functional characteristics
Authors: Tian Peng , Wang Yunjia , Wang Yong , Yang Yuan
Published: April 2024

Indoor navigation networks serve as the foundation for indoor pedestrian navigation services. However, current graph‐based topological network models cannot easily represent complex indoor structures in a manner consistent with user behaviour and cognitive patterns, and thus cannot support fine‐grained indoor navigation analysis services. To enhance the rationality of the model, we considered the influences of morphological and functional characteristics of indoor spaces on pedestrian movement and proposed a method for classifying navigation spaces. This method, based on convex space segmentation, defines morphological and functional characteristic functions, classifying indoor navigation spaces as either corridors or open spaces, which suitable for representing as median axis models or visual graphs, respectively. These categories supported the creation of topological network models for route planning analysis. Indoor map experiments confirmed the effectiveness of our method in identifying various types of corridors and open spaces, that addressing the limitations of width‐based parameters, even in complex indoor settings.
Analytically derived disturbance rejection‐based PID controller tuning for second‐order plus dead time plants
Authors: Tavakoli Saeed , Safaei Marzieh
Published: April 2024

This letter proposes a proportional‐integral‐derivative (PID) design method for second‐order plus dead time models based on a desired closed‐loop transfer function for load disturbance changes. Also, tuning rules for single integrating first‐order plus dead time models are provided. Using a two‐degree‐of‐freedom control scheme, the design problem considers load disturbance rejection, robustness to model uncertainties, and setpoint tracking. Three examples are used to assess the performance of the proposed method. Finally, the results are compared to two popular PID control design methodologies, skogestad internal model control or skogestad IMC (SIMC) and improved SIMC (iSIMC).
Application of maximum statistical entropy in formulating a non-gaussian probability density function in flow uncertainty analysis with prior measurement knowledge
Authors: Ramnath Vishal
Published: April 2024

In mechanical, civil and chemical engineering systems the accuracies of flow measurement instruments is conventionally specified by certified measurement capabilities (CMCs) that are symmetric, however it is physically possible for some flow instruments and equipment to exhibit asymmetric non-Gaussian behaviour. In this paper the influence of non-Gaussian uncertainties is investigated using direct Monte Carlo simulations to construct a probability density function (PDF) using representative non-Gaussian surface roughness data for a commercial steel pipe friction factor. Actual PDF results are compared and contrasted with a symmetric Gaussian PDF, and reveal inconsistencies in the statistical distributions that cannot be neglected in high accuracy flow measurements. The non-Gaussian PDF is visualized with a kernel density estimate (KDE) scheme to infer an initial qualitative shape of the actual PDF using the approximate locations of the normalized peaks as a initial metrologist estimate of the measurement density. This is then utilized as inputs in a maximum statistical entropy functional to optimize the actual non-Gaussian PDF using a nonlinear optimization of Lagrange multipliers for a mathematically unique PDE. Novelties in the present study is that a new methodology has been developed for statistical sampling from non-monotonic non-Gaussian distributions with accompanying Python and Matlab/GNU Octave computer codes, and a new methodology for utilizing metrologist's expert prior knowledge of PDF peaks and locations for constructing an a priori estimate of the shape of unknown density have been incorporated into the maximum statistical entropy nonlinear optimization problem for a faster and more efficient approach for generating statistical information and insights in constructing high accuracy non-Gaussian PDFs of real world messy engineering measurements.
Afrikanische Medizin in Togo – Eine Studienreise der
GPT
Authors: Schmidt Mathias , Hensel Andreas , Langhorst Jost
Published: April 2024

Die Gesellschaft für Phytotherapie hatte im Frühjahr 2023 eine Einladung zu einem
Symposium des „Centre Omnithérapeutique Africain“ (COA) in Togo erhalten. Das COA
betreibt Forschung und Lehre im Bereich der afrikanischen traditionellen Medizin und
bietet einen Masterstudiengang in diesem Sektor an. Das COA stößt in eine Lücke, die
von der Ausbildung an medizinischen Instituten nicht abgedeckt wird. Vor allem in
den ländlichen Gebieten abseits der Küste mit der Hauptstadt Lomé haben viele
Patienten wenig bis keinen Zugang zu Ärzten und Apotheken. Sie besuchen daher
traditionelle Heiler, die auf einen über Generationen hinweg übermittelten
Wissensschatz zurückgreifen. Ziel des COA ist es, dieses tradierte Wissen mit
modernen wissenschaftlichen Methoden zu untersuchen und Mittel mit nachweisbaren
Effekten der Therapie zugänglich zu machen.
Amerikanische Traubenkirsche – Prunus serotina
Ehrh.
Authors: Magiera Anna , Dowgird Aleksandra
Published: April 2024

Die Amerikanische Traubenkirsche (Prunus serotina Ehrh.) ist eine Baum-
oder Großstrauchart aus der Familie der Rosengewächse, die in Nordamerika
beheimatet und heute auch in ganz Europa verbreitet ist. In heimischen Gebieten
werden die Früchte, Rinde und Zweige von P. serotina seit Jahrhunderten
in der traditionellen Medizin hochgeschätzt. Sie werden insbesondere als
Heilmittel zur Behandlung von Magen-Darm-Beschwerden sowie zur Linderung von
Atemwegsbeschwerden oder als Beruhigungsmittel eingesetzt. Dieses Manuskript
setzt sich zum Ziel, den aktuellen Wissensstand über die o.g. Art, ihre
Inhaltsstoffe und ihr therapeutisches Potenzial zusammenzufassen.
Liebe Leserinnen, liebe Leser …
Authors: Uehleke Bernhard
Published: April 2024

30 Jahre Traditionelle Arzneimittel – Auslaufmodell einer Übergangslösung oder
Zukunft der Phytotherapie?

In der 5. AMG-Novelle von 1994 findet sich erstmals im Gesetz der Begriff
„Traditionelle Arzneimittel“. Zuvor waren solche freiverkäuflichen Mittel zur
Stärkung der Gesundheit innerhalb des Bundesgesundheitsamtes intern als „Tonika“
bezeichnet worden. „Tonika“ gefielen aber als Begriff mit seiner vielfachen
Bedeutung von einer längst überholten Pharmakologie bis hin zum fragwürdigen
Potenzmittel weder den aktiven Mitgliedern der Gesellschaft für Phytotherapie noch
der Apothekerschaft, die diese außerhalb der Apotheke vertriebenen Arzneimittel am
liebsten abgeschafft sehen wollten. Und es gab damals durchaus schon – lange bevor
die Nahrungsergänzungsmittel aktuell wurden – Ansätze, eine neue Klasse von
„Gesundheitsmitteln“ zu schaffen, die dann nicht mehr zu den Arzneimitteln gehören
sollten.
Grapefruit Seed Extract Reduces Gastrointestinal
Symptoms
Authors: Uehleke Bernhard , Storr Martin , Hörning Martin
Published: April 2024

In this explorative longitudinal survey, self-reported data was collected from
persons suffering from chronic gastrointestinal symptoms, who were seeking
relief employing self-medication with a grapefruit seed extract (GKE). This is
not a clinical trial nor a non-interventional study, but an explorative
longitudinal survey with self-reports. The data was collected online and there
were no personal contacts with a physician or a study nurse. Participants
followed their own decision to use GKE and to provide their data to a data
retrieval system, following informed consent according to existing national
regulations on data protection. The test product was provided by the sponsor to
make sure that the correct product was used for the intended observation
period.

Drop in criteria were chronic gastrointestinal symptoms, including those of
functional dyspepsia (FD, resp. non-ulcer dyspepsia NUD) and/or irritable bowel
syndrome (IBS) for more than 4 weeks, resulting in a score of an expanded Nepean
Index (‘total gastrointestinal score’) higher than 20. Symptoms were documented
4–12 days (VA) prior to GKE use on day 1 and then on day 1, days 28, 42 and 56
of continuous oral use. New symptoms, predominating symptoms, stool habits,
amount of oral intake and global status was retrieved every day during the
observation period. On day 56 some global assessments were additionally
recorded.

The evaluation cohort was intended to be at least 100, and within the survey
cohort we were able to evaluate 100 subjects (15 m and 85 f). Total
gastrointestinal symptom score decreased from a mean (±SD) of 78.7±36.9 points
by 26.4% on day 14, by 53.1% on day 28, by 58.7% on day 42, and by 49.9% on day
56, when compared to day 1. Upper gastrointestinal symptoms like heartburn
improved better compared to lower GI symptoms (by 57.9% versus 47.3% on day 56).
Overall complaints were rated as “very strongly improved” by 30%, “strongly
improved” by 42%, “somewhat improved” or “unchanged” by 20% and as
“deteriorated” by 1%. GKE was tolerated well. Minor adverse events reported were
judged as most probably unrelated by the authors. More than half of the
participants rated the intake as “very pleasant” or “pleasant” and intended to
continue GKE beyond the observation period.

In this prospective uncontrolled survey, GKE seemed to improve GI-symptoms, based
on users reports. These results need to be confirmed in controlled clinical
trials proofing efficacy and tolerance of GKE in functional GI-diseases. Data
collected from participants without any personal contact bear a high risk of
bias. Evaluation of self-treatment as presented here is clearly restricted to
marketed products and may report interesting details of self-treatment outside
prescription settings.
Association Analysis of Dietary Inflammatory Index and Gestational
Diabetes Mellitus: Based on National Health and Nutrition Examination Survey
Database
Authors: Zeng Yamin , Piao Yina
Published: April 2024

Objective This study focused on the association of the Dietary
Inflammatory Index (DII) with the risk of gestational diabetes mellitus (GDM)
using data from the National Health and Nutrition Examination Survey
(NHANES).

Methods Data from two cycles of NHANES (2007–2010) were analyzed. Weighted
logistic regression models were constructed to explore the relationship between
DII and GDM. Stratified and subgroup analyses with adjustment for confounding
factors were carried out to explore the association between DII and GDM.
Mediation analysis was conducted to investigate potential mediating factors.

Results A total of 1,421 samples were analyzed. Based on the weighted
logistic regression model, a strong positive association was observed between
DII score and GDM risk (OR: 1.14, 95%CI: 1.02–1.26, P<0.01),
suggesting that a pro-inflammatory diet could considerably increase the
likelihood of GDM occurrence. This positive association was particularly
significant in populations who consume alcohol (OR:1.17, 95%CI: 1.03–1.34,
P<0.01) and have a body mass index>30 kg/m² (OR: 1.18, 95% CI:
1.01–1.38, P<0.05). Mediation analysis indicated that the white blood
cell count mediated the association between DII and GDM, with an indirect effect
of 0.000828 (95% CI: 0.000226–0.001347, P=0.001) and a mediation
proportion of 8.01%. Specifically, the neutrophil count as a component
contributed to this mediation effect (0.000774, 95% CI: 0.00014–0.001063,
P=0.001), with a mediation proportion of 7.59%.

Conclusion A pro-inflammatory diet in women elevates the likelihood of GDM
occurrence. An anti-inflammatory dietary pattern may be a protective
intervention for GDM.
Implementation des intraoperativ chirurgisch-gesetzten, laparoskopisch-sicht-kontrollierten „Transversus-Abdominis-Plane“-Blockes mit Bupivacain bei elektiven laparoskopischen Darmresektionen
Authors: Kaufmann Mario , Orth Vanessa , Dorwarth Tim-Janick , Benrath Justus , Gerber Benjamin , Ghezel-Ahmadi David , Reissfelder Christoph , Herrle Florian
Published: April 2024

Das moderne multimodale perioperative Schmerzmanagement bietet sowohl auf anästhesiologischer als auch auf chirurgischer Seite diverse Möglichkeiten, den postoperativen Schmerz optimal zu kontrollieren. Bei starker Empfehlung der aktuellen ERAS-Kolorektal-Guidelines (2018) zur Nutzung eines laparoskopischen „Transversus-Abdominis-Plane“-Block (L-TAP) wurde dieser im Universitätsklinikum Mannheim modifiziert, um den Patienten sowohl ein möglichst schmerzarmes Erwachen im Aufwachraum als auch eine schmerzfreie 1. postoperative Nacht zu ermöglichen.

Der L-TAP ist bei allen laparoskopisch-kolorektalen Operationen indiziert. Insbesondere bei Verfahren, die einen vergrößerten Bergeschnitt (z. B. Pfannenstiel-Schnitt im Unterbauch) zur Bergung des Präparates erfordern.

Der L-TAP wird zweizeitig, am Anfang der Operation nach Anlegen des Pneumoperitoneums, sowie am Ende der Operation, vor Entfernung der Trokare, durchgeführt. Insgesamt werden bei dieser L-TAP-Technik ca. 266 mg Bupivacainhydrochlorid verabreicht. Die Mischung aus 30 ml Natriumchlorid 0,9% und 60 ml Bupivacainhydrochlorid 0,5% wird an 3 Lokalisationen je Bauchseite injiziert. Die Injektionsstellen befinden sich in der vorderen Axillarlinie 2 cm oberhalb der Crista iliaca, 2 cm oberhalb der erstgenannten Injektionsstelle sowie in der Medioklavikularlinie 2 cm unterhalb des Rippenbogens. An diesen Stellen wird dem Patienten jeweils ca. 7 ml gespritzt. Während dieser Injektionen findet eine intraabdominelle Sichtkontrolle nach Setzung des Kameratrokars laparoskopisch statt. Dabei ist darauf zu achten, dass sich zwischen den Muskelschichten langsam eine deutliche Vorwölbung nach intraabdominell ausbildet.

Durch ein intensives postoperatives Monitoring der Patienten und Schulung des Personals konnte gezeigt werden, dass die Patienten signifikant profitieren durch eine streng korrekte Durchführung des L-TAP. So konnte der postoperative mediane Gesamtmorphiumbedarf der ersten 3 Tage von 25,625 mg (0–150 mg) für einen inkorrekt durchgeführten L-TAP (n = 13) auf 5,625 mg (0–215,625 mg) für einen korrekt durchgeführten L-TAP (n = 49) signifikant reduziert werden (p = 0,024). Die Patienten profitierten ebenfalls subjektiv von der Durchführung eines korrekten L-TAP mit einer signifikanten Reduktion der Schmerzen auf der NRS im Aufwachraum von 4 (0–7) auf 1 (0–7; p = 0,044).
A framework for the analysis of historical newsreels
Authors: Oiva Mila , Mukhina Ksenia , Zemaityte Vejune , Karjus Andres , Tamm Mikhail , Ohm Tillmann , Mets Mark , Chávez Heras Daniel , Canet Sola Mar , Juht Helena Hanna , Schich Maximilian
Published: April 2024

Audiovisual news is a critical cultural phenomenon that has been influencing audience worldviews for more than a hundred years. To understand historical trends in multimodal audiovisual news, we need to explore them longitudinally using large sets of data. Despite promising developments in film history, computational video analysis, and other relevant fields, current research streams have limitations related to the scope of data used, the systematism of analysis, and the modalities and elements to be studied in audiovisual material and its metadata. Simultaneously, each disciplinary approach contributes significant input to research reducing these limitations. We therefore advocate for combining the strengths of several disciplines. Here we propose a multidisciplinary framework for systematically studying large collections of historical audiovisual news to gain a coherent picture of their temporal dynamics, cultural diversity, and potential societal effects across several quantitative and qualitative dimensions of analysis. By using newsreels as an example of such complex historically formed data, we combine the context crucial to qualitative approaches with the systematicity and ability to cover large amounts of data from quantitative methods. The framework template for historical newsreels is exemplified by a case study of the “News of the Day” newsreel series produced in the Soviet Union during 1944–1992. The proposed framework enables a more nuanced analysis of longitudinal collections of audiovisual news, expanding our understanding of the dynamics of global knowledge cultures.
Features of nanocontact formed using point electrical breakdown of a niobium oxide nanolayer
Authors: Bondarenko S. I. , Krevsun A. V. , Koverya V. P.
Published: April 2024

The electrical characteristics of a point section of niobium oxide between a massive cathode made of a superconducting indium-tin alloy and a niobium film before the oxide breakdown and the nanocontact that appears after the breakdown of the oxide at room temperature have been studied. The dependencies of the point breakdown voltage of the oxide and the resistance of nanocontacts on the method of breakdown and the thickness of the oxide in the range of 15–60 nm have been established. In particular, a minimum value of the breakdown current has been established (about 1 μA), below which breakdown does not occur. The voltage-current characteristic (VCC) of the oxide has a semiconductor character and indicates the dependence of the breakdown voltage of the oxide on its polarity. The VCC of the nanocontact is nonlinear, which is associated with phase transitions in the nanocontact material caused by its heating by the transport current.
NiGa2O4 interfacial layers in NiO/Ga2O3 heterojunction diodes at high temperature
Authors: Egbo Kingsley , Garrity Emily M. , Callahan William A. , Chae Chris , Lee Cheng-Wei , Tellekamp Brooks , Hwang Jinwoo , Stevanovic Vladan , Zakutayev Andriy
Published: April 2024

NiO/Ga2O3 heterojunction diodes have attracted attention for high-power applications, but their high temperature performance and reliability remain underexplored. Here, we report the time evolution of the electrical properties in the widely studied p-NiO/n-Ga2O3 heterojunction diodes and formation of NiGa2O4 interfacial layers at high temperatures. Results of our thermal cycling experiment show an initial leakage current increase which stabilizes after sustained thermal load, due to reactions at the NiO–Ga2O3 interface. High-resolution TEM microstructure analysis of the devices after thermal cycling indicates that the NiO–Ga2O3 interface forms a ternary compound at high temperatures, and thermodynamic calculations suggest the formation of the spinel NiGa2O4 layer between NiO and Ga2O3. First-principles defect calculations find that NiGa2O4 shows low p-type intrinsic doping and hence can serve to limit electric field crowding at the interface. Vertical NiO/Ga2O3 diodes with intentionally grown ∼5 nm thin spinel-type NiGa2O4 interfacial layers show an excellent device ON/OFF ratio of >1010 (± 3 V), VON of ∼1.9 V, and increased breakdown voltage of ∼1.2 kV for an initial unoptimized 300 μm diameter device. These p–n heterojunction diodes are promising for high-voltage, high temperature applications.
Fostering solar hybrid cooling systems in MENA region: A techno-economic and emission reduction assessment
Authors: Hasanain Bassam
Published: April 2024

Solar driven cooling system is a promising and sustainable substitute for conventional cooling systems to soften the impact of energy deficit and environmental degradation. In this study, a solar hybrid cooling system for an institutional building is investigated, which combines solar photovoltaic (PV) technology with traditional vapor compression systems and/or absorption cooling systems. The performance of the proposed solar hybrid cooling system is simulated and compared at four (04) locations in Middle East and North Africa (MENA) region: Riyadh (Saudia Arabia), Dubai (United Arab Emirates), Doha (Qatar), and Jaww (Bahrain), with different cooling system configurations from technical, economic, and environmental standpoints. The simulation findings show that the solar driven absorption chiller reduces the maximum CO2 emissions by 42.7% in Riyadh, while the solar driven compressor system gives a maximum Greenhouse gas emissions reduction (99.1%) for the location of Dubai. To determine the most practical design in terms of economics, metrics such as net present value, payback, and benefit–cost ratio (BCR) and several cooling scenarios are also rigorously studied. According to model findings, the solar absorption cooling system presented the most feasible scenario with the shortest payback of 5.8 years, the highest internal rate of return (IRR) of 38.8%, and BCR of 5.4% for the location of Dubai, and the same trend holds for all other locations. Conversely, the solar-powered vapor compression system was the least suitable option for Riyadh city, with the longest payback period of 21.9 years, the lowest IRR of 2.4, and a BCR of −0.06. In addition, optimization results show that ground mounted PV systems outperform building integrated PV (BIPV) systems owing to their higher capacity factor: 21% in case of PV and 12.8% in case of BIPV systems.
Review and meta-analysis of electron temperatures from high-intensity laser–solid interactions
Authors: Rusby D. R. , Kemp A. J. , Wilks S. C. , Miller K. G. , Sherlock M. , Chen H. , Simpson R. A. , Mariscal D. A. , Swanson K. , Djordjević B. Z. , Link A. J. , Williams G. J. , Mackinnon A. J.
Published: April 2024

The accelerated electron spectrum from high-intensity laser–solid interaction is often conveniently described using a Boltzmann distribution, whose temperature is known within the field as the hot-electron temperature. The importance of the electron temperature is highlighted by the sheer number of experimental and simulation studies on the subject over the past three decades. Recently, multi-kJ, multi-ps pulses have yielded electron spectra with temperatures far beyond the expected ponderomotive result. Expressions that predict the electron temperature considering laser parameters beyond intensity and wavelength have been developed, albeit using small datasets. In this review, we present what is, to the best of our knowledge, the largest dataset of electron temperatures gathered from experimental measurements and particle-in-cell simulations. This dataset allows us to compare existing analytical and empirical hot-electron temperature scaling models over a wide parameter range. We also develop new scaling models that incorporate the laser pulse duration of the laser and the plasma scale length. Three models that include pulse-duration and scale length dependence are especially successful at predicting both simulated and experimental data. The dataset will soon be made publicly available to encourage further investigation.
Enhancing flexibility in BaTiO3:Sm3+ freestanding nanofiber membranes through Poisson's ratio design
Authors: Li Yang , Zhang Yongcheng , Wang Dehua , Hou Limei , Du Shanmei , Deng Yang , Du Yanfeng , Xin Yingfei , Fu Chongyang , Jin Mingliang , Gu Yan , Wang Xiaoxiong
Published: April 2024

In recent years, flexible functional materials have attracted increasing interest, but there is a lack of designing mechanisms of flexibility design with superstructures. In traditional engineering mechanics, the maximum bending strain (MBS) was considered universal for describing the bendable properties of a given material, leading to the universal designing method of lowering the dimension such as thin membranes designed flexible functional materials. In this work, the MBS was found only applicable for materials with uniformly distributed Poisson's ratio, while the MBS increases with the thickness of the given material in case there is a variation Poisson's ratio in different areas. This means the MBS can be enhanced by certain Poisson's ratio design in the future to achieve better flexibility of thick materials. Here, the macroscopic freestanding inorganic functional BaTiO3:Sm3+ (BTO:S) nanofiber membranes, which have a nonconstant Poisson's ratio response on stress/strain for creating nonuniformly distributed Poisson's ratio, were proven applicable for designing larger MBS and lower Young's modulus for flexible functional materials.
Study on rock strength weakening in multi-stage acid fracturing using continuous strength test
Authors: Wang Qing , Zhou Fujian , Su Hang , Zhang Siyu , Yu Fuwei , Dong Rencheng , Li Junjian , Chen Zhangxin
Published: April 2024

Multi-stage acid fracturing can boost productivity in low-permeability limestone reservoirs, with success hinging on differential etching and the strength of undissolved regions to keep fractures open. Traditional rock strength test methods have strong randomness and error. This study explores the influence of four acid systems (hydrochloric acid, single-phase retarded acid, gelled acid, and emulsified acid) on fracture surface strength based on a new continuous strength test method. The rock strength weakening variation under different acid types and injection conditions was quantified, and the mechanism of single-phase retarded acid slowing down rock strength reduction was revealed. The results indicated that the fracture surfaces were reduced to a lesser extent than in traditional rock mechanical failure studies. Hydrochloric acid caused up to 28% of rock strength depletion, followed by 23% for gelled acid, 18% for emulsified acid, and 11.8% for single-phase retarded acid. Adjusting the acid injection parameters revealed that longitudinal leak-off at the fracture surface changes the rock's strength failure tendency. The microscopic results confirmed that the appropriate acid-rock reaction rate and viscosity are beneficial in reducing strength by forming the dominant wormhole that “siphons” the subsequent acid more profoundly into the formation, thereby reducing the reaction of the acid with the fracture surface. This study can help to understand better the mechanism by which acid reduces the strength of fracture surfaces and can provide guidance for selecting appropriate acid fluids for acid fracturing in low-permeability limestone reservoirs.
Abnormal temperature-dependent transient electroluminescence spikes induced by the leakage of hole carriers in organic light-emitting diodes
Authors: Chen Jing , Yang Jun , Zhang Keyi , Zhou Yinqiong , Yang Song , Lu Hong , Li Zuo , Yi Yingfei , Chen Lihong , Zhang Sijie , Chen Xiaoli , Xiong Zuhong
Published: April 2024

The amplitude of the emission spike at the transient electroluminescence (TEL) falling edge is an important benchmark for evaluating the quantities of trapped charges existed in organic light-emitting diodes and often shows a normal temperature dependence which increases with the decreasing temperature. Surprisingly, an unreported abnormal temperature-dependent TEL spike was observed in this work. A series of experimental results relevant to the electroluminescence spectrum and TEL measurements demonstrate that this abnormal temperature-dependent behavior is induced by the leakage of hole carriers from the emission layer (EML) to an electron transport layer (ETL). After the voltage pulse is turned off, these holes already leaked into the ETL drift back toward the EML, subsequently engaging in radiative recombination with trapped electrons on guest molecules to generate a spike at the TEL falling edge. However, the drift process is hindered by the reduced carrier mobility of the ETL material with the decrease in temperature. As a result, the spike intensity weakens as the temperature decreases, which contradicts the conclusions reported in previous literatures. Therefore, this study not only leads to the reconsideration for the judgment criteria of the number of trapped charges but also provides valuable insight into the TEL research field of organic optoelectronic devices.
A comprehensive deep learning geometric shape optimization framework with field prediction surrogate and reinforcement learning
Authors: Ma Hao , Liu Jianing , Ye Mai , Haidn Oskar J.
Published: April 2024

The optimization of aerodynamic components' geometric shapes demands a novel technical approach for adaptive and efficient exploration and decision-making within the design space. In this study, we introduce an innovative shape optimization framework that leverages deep reinforcement learning with neural network surrogate models. The field prediction surrogate, realized by two distinct U-net architectures, can efficiently generate holistic field solutions based on the transformed mesh coordinates. Subsequently, an inference engine dynamically calculates the key metric of the flow fields, serving as the objective function for the subsequent geometry-aware Deep Q network (DQN)-based optimization. The framework's efficacy is validated using a rocket nozzle as an illustrative example. During surrogate validation, under both friction and frictionless conditions, the l1 errors of the entire flow field of both the U-net vision transformer (ViT) and U-net convolutional neural network (CNN) architectures are less than 0.4%. The proposed U-net ViT consistently outperforms U-net CNN, and the superiority is particularly evident in complex flow areas, outlet sections, and vacuum thrust prediction. Following training, the DQN model is employed to explore the design variable space. The B-spline defining profile successfully is optimized to a final expanding segment shape with improved thrust. Under frictionless conditions, it closely approaches the theoretical optimum. In the practical condition considering friction, the optimized shape gains a 2.96% thrust improvement. The results demonstrate that the proposed framework, especially when coupled with U-net ViT, exhibits enhanced accuracy and adaptability for shape optimization tasks.
Hypersonic boundary layer over a flat plate with slip and shear nonequilibrium effects
Authors: Ou Jihui , Chen Jie
Published: April 2024

Near-space hypersonic vehicles could encounter significant rarefied nonequilibrium effects during the flight through atmosphere, which largely influence the gas-surface momentum and heat transfer. In this paper, hypersonic boundary layer over a flat plate with velocity slip, temperature jump, and shear nonequilibrium effects is theoretically considered. The slip boundary conditions and nonlinear transport relations are embedded into the boundary-layer equations to describe the flow. Local similar solutions are derived, and key parameters for characterizing slip and shear nonequilibrium effects are determined. The velocity-slip and temperature-jump effects are determined by [(2−σu)/σu]Mae/Rex and [(2−σT)/σT]Mae/Rex respectively, and the shear nonequilibrium effect is characterized by Mae2/Rex. The obtained boundary-layer solutions are compared with the Navier–Stokes solutions for a Mach 4.5 slip flow, and the results of Direct Simulation Monte Carlo for a Mach 10 rarefied flow, good agreements are achieved. The separate and combined effects of velocity slip, temperature jump, and shear nonequilibrium on boundary-layer solutions and momentum/heat transfer are clarified. The results show that both the slip and shear nonequilibrium effects cause the boundary layer to become thinner and decrease the skin friction and Fourier heat conduction. However, with including sliding friction, the total heat flux might even increase as the slip degree increases. These results provide valuable insight into the boundary-layer characteristics of hypersonic near-continuum flows.
Lattice engineering of high-entropy olivine-type lithium metal phosphate as high-voltage cathodes
Authors: Fan Juntian , Wang Tao , Yuan Yating , Borisevich Albina , Do-Thanh Chi-Linh , Yang Zhenzhen , Dai Sheng
Published: April 2024

Engineering of high-entropy cathode materials for lithium-ion batteries has been actively pursued owing to the outstanding conductivity of high-entropy materials benefited from the maximum entropy and unique antisite disordering structure. Olivine lithium metal phosphates such as LiMnPO4 and LiNiPO4 feature high working voltages but low capacities due to their insulation nature. In this work, the synthesis of the high-entropy lithium metal phosphate materials (HELMPs) is realized by combining mechanochemistry with a calcination method. By regulating lattice of HELMPs, the high-entropy Li(Mn0.35Fe0.35Co0.1Mg0.1Ca0.1)PO4 reveals three typical high-voltage plateaus in charge–discharge curves corresponding to the redox of Fe, Mn, and Co in the voltage range of 2.0–4.9 V vs Li+/Li, and a much higher initial capacity than LiMnPO4 (104 vs 15 mAh g−1).
Tuning grain boundary cation segregation with oxygen deficiency and atomic structure in a perovskite compositionally complex oxide thin film
Authors: Guo Huiming , Vahidi Hasti , Kang Hyojoo , Shah Soham , Xu Mingjie , Aoki Toshihiro , Rupert Timothy J. , Luo Jian , Gilliard-AbdulAziz Kandis Leslie , Bowman William J.
Published: April 2024

Compositionally complex oxides (CCOs) are an emerging class of materials encompassing high entropy and entropy stabilized oxides. These promising advanced materials leverage tunable chemical bond structure, lattice distortion, and chemical disorder for unprecedented properties. Grain boundary (GB) and point defect segregation to GBs are relatively understudied in CCOs even though they can govern macroscopic material properties. For example, GB segregation can govern local chemical (dis)order and point defect distribution, playing a critical role in electrochemical reaction kinetics, and charge and mass transport in solid electrolytes. However, compared with conventional oxides, GBs in multi-cation CCO systems are expected to exhibit more complex segregation phenomena and, thus, prove more difficult to tune through GB design strategies. Here, GB segregation was studied in a model perovskite CCO LaFe0.7Ni0.1Co0.1Cu0.05Pd0.05O3−x textured thin film by (sub-)atomic-resolution scanning transmission electron microscopy imaging and spectroscopy. It is found that GB segregation is correlated with cation reducibility—predicted by an Ellingham diagram—as Pd and Cu segregate to GBs rich in oxygen vacancies (VO··). Furthermore, Pd and Cu segregation is highly sensitive to the concentration and spatial distribution of VO·· along the GB plane, as well as fluctuations in atomic structure and elastic strain induced by GB local disorder, such as dislocations. This work offers a perspective of controlling segregation concentration of CCO cations to GBs by tuning reducibility of CCO cations and oxygen deficiency, which is expected to guide GB design in CCOs.
Direct observation of radio-frequency negative differential resistance in GaN-based single drift region IMPATT diodes
Authors: Zhu Zhongtao , Cao Lina , Jönsson Adam , Xu Pengcheng , Xie Jinqiao , Fay Patrick
Published: April 2024

We report the direct observation of radio-frequency negative differential resistance, via on-wafer S-parameter measurements, in GaN-based impact ionization avalanche transit time (IMPATT) diodes. Clear signatures of reflection gain are observed from 18.7 to 30.6 GHz. These observations have been made possible by suppressing the reverse leakage current (and thereby parasitic shunt conductance) by optimization of the fabrication process, in conjunction with the use of pulsed measurements to suppress device self-heating. Consistent with avalanche-dominated behavior, the measured DC reverse bias current–voltage measurements show a positive temperature coefficient of breakdown. For the high-frequency on-wafer characterization, pulsed-bias S-parameter measurements with low (0.0067%) duty cycle were used to mitigate thermal effects. The measured avalanche frequency aligns closely with theoretical predictions based on Gilden and Hines' small signal model [Gilden and Hines, IEEE Trans. Electron Devices ED-13(1), 169–175 (1966)], measured impact ionization coefficients [Cao et al., Appl. Phys. Lett. 112(26), 262103 (2018)], and experimental saturation velocity measurements [Bajaj et al., Appl. Phys. Lett. 107(15), 153504 (2015)]; this excellent agreement confirms IMPATT operation and provides insights needed to further optimize device performance.
Review of electron emission and electrical breakdown in nanogaps
Authors: Li Yimeng , Ang Lay Kee , Xiao Bing , Djurabekova Flyura , Cheng Yonghong , Meng Guodong
Published: April 2024

With the continual miniaturization of electronic devices, there is an urgent need to understand the electron emission and the mechanism of electrical breakdown at nanoscale. For a nanogap, the complete process of the electrical breakdown includes the nano-protrusion growth, electron emission and thermal runaway of the nano-protrusion, and plasma formation. This review summarizes recent theories, experiments, and advanced atomistic simulation related to this breakdown process. First, the electron emission mechanisms in nanogaps and their transitions between different mechanisms are emphatically discussed, such as the effects of image potential (of different electrode's configurations), anode screening, electron space-charge potential, and electron exchange-correlation potential. The corresponding experimental results on electron emission and electrical breakdown are discussed for fixed nanogaps on substrate and adjustable nanogaps, including space-charge effects, electrode deformation, and electrical breakdown characteristics. Advanced atomistic simulations about the nano-protrusion growth and the nanoelectrode or nano-protrusion thermal runaway under high electric field are discussed. Finally, we conclude and outline the key challenges for and perspectives on future theoretical, experimental, and atomistic simulation studies of nanoscale electrical breakdown processes.
Rotational spectrum, structure, and quadrupole coupling of cyclopropylchloromethyldifluorosilane
Authors: Davies Alexander R. , Hanna Abanob G. , Lutas Alma , Guirgis Gamil A. , Grubbs G. S.
Published: April 2024

Cyclopropylchloromethyldifluorosilane, c-C3H5SiF2CH2Cl, has been synthesized, and its rotational spectrum has been recorded by chirped-pulse Fourier transform microwave spectroscopy. The spectral analysis of several isotopologues indicates the presence of two distinct conformations in the free-jet expansion, which are interconvertible through a rotation of the chloromethyl group. A partial substitution structure is presented for the lower energy conformation and is compared to the equilibrium structure obtained from quantum chemical calculations. Additionally, the presence of the chlorine nucleus leads to the rotational transitions splitting into multiple hyperfine components and χaa, a measure of the electric field gradient along the a axis, is unusually small at merely +0.1393(73) MHz. Various common ab initio and density functional theory methods fail to predict good quadrupole coupling constants (in the principal axis system) that adequately reproduce the observed hyperfine splitting, although diagonalizing the quadrupole coupling tensor from the principal axis system into a nucleus-centered axis system reveals that, overall, these methods calculate reasonably the electric field gradient about the chlorine nucleus. Finally, a total of nine electric dipole forbidden, quadrupole allowed transitions are observed in the rotational spectra of the parent species of the higher energy conformation and the 37Cl isotopologue of the lower energy conformation. These include those of x-type (no change in parity of Ka or Kc), which, to our knowledge, is the first time such transitions have been observed in a chlorine-containing molecule.
Vortex bifurcation and air entrainment mitigation using multi-point intakes
Authors: Mondal Rahul Kumar , Rohilla Lokesh , Kumar Parmod
Published: April 2024

Air entrainment is a concern of paramount importance in the process industries, including nuclear power plant, hydraulic machines, water treatment plants, hydrocyclones, and power generation turbines. The ingression of the air into the equipment results in the reduction of the hydraulic efficiency. In the current paper, a combined experimental and numerical investigation has been performed using the commensurate high-speed photography and volume of fluid-based numerical simulations. The mitigation strategies for the reduction of the air ingression include the reduction of the critical height by increasing the number of intakes and changing the intake configuration. The viability of these solutions and the hydrodynamics behind the interfacial evolution leading to the air entrainment have been studied in detail. The air ingression progresses with the establishment of the flow patterns ranging from bubbly flow, slug flow, to the annular flow. The reduction of the critical height can be accomplished by increasing the number of intakes for the same cross-sectional area leading to the reduction in the Froude number Fr=Vdown/gHlocal<1. Further increasing the number of intakes beyond four leads to the minimal reduction in the critical height in the tank.
Ultrafast electron diffraction of photoexcited gas-phase cyclobutanone predicted by ab initio multiple cloning simulations
Authors: Makhov Dmitry V. , Hutton Lewis , Kirrander Adam , Shalashilin Dmitrii V.
Published: April 2024

We present the result of our calculations of ultrafast electron diffraction (UED) for cyclobutanone excited into the S2 electronic state, which is based on the non-adiabatic dynamics simulations with the Ab Initio Multiple Cloning (AIMC) method with the electronic structure calculated at the SA(3)-CASSCF(12,12)/aug-cc-pVDZ level of theory. The key features in the UED pattern were identified, which can be used to distinguish between the reaction pathways observed in the AIMC dynamics, although there is a significant overlap between representative signals due to the structural similarity of the products. The calculated UED pattern can be compared with the experiment.
Spiral eutectic growth dynamics facilitated by space Marangoni convection and liquid surface wave
Authors: Wang Haipeng , Liu Dingnan , Zheng Chenhui , Zhao Jiongfei , Chang Jian , Hu Liang , Liao Hui , Geng Delu , Xie Wenjun , Wei Bingbo
Published: April 2024

Eutectic alloys display excellent application performances since the essential function of coupled microstructures is quite different from that of single-phase and peritectic alloys. However, due to the strong natural convection within liquid alloys under normal gravity, the eutectic growth process on earth usually produces traditional rod-like or lamellar composite microstructures, which hinders the exploration of distinctive coupled growth patterns. Here, we carried out the rapid solidification of hypoeutectic Zr64V36 alloy to explore novel coupled growth dynamics aboard the China Space Station under a long-term stable microgravity condition. An extreme liquid undercooling of 253 K was achieved for this refractory alloy, displaying a strong metastability in outer space. We find that a radial coupled pattern grew out of the nucleation site, accompanying a ripple-like surface microstructure. This resulted from the rapid eutectic growth within a highly undercooled alloy in combination with a liquid surface wave excited by the electrostatic field under microgravity. Especially, a spiral coupled growth mode occurred during radial eutectic growth and surface wave spreading, which were controlled by the Marangoni convection effect on the fluid flow pattern and eutectic growth dynamics. Our findings contribute to the coupled growth investigation by modulating gravity levels to develop multi-pattern microstructures.
The photothermal interaction of a viscothermoelastic semiconducting ceramic solid sphere under the Green–Naghdi heat conduction model
Authors: Youssef Hamdy M. , El-Bary Alaa A.
Published: April 2024

This work introduces a new mathematical model for viscothermoelastic semiconducting solid spheres of ceramic materials considering the photothermal interaction using three types of the Green–Naghdi heat conduction model. The outer surface of a solid sphere is loaded thermally using ramp-type heat as a boundary condition. Following that, Laplace transforms and their inversion forms have been applied. The figures show that the mechanical relaxation time and ramp-time heat parameters have significant effects on the increase in carrier density and temperature, in addition to strain, displacement, the average of principal stresses, and the strain-energy density. The energy produced by viscothermoelastic semiconducting materials based on photothermal interaction may be controlled by the ramp-time heat parameter. The novelty of this work is to test the three types of the Green–Naghdi heat conduction model and apply the model to zirconia, a ceramic material.