bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on intelligent recognition method for self‐blast state of glass insulator based on mixed data augmentation
Authors: Peng Siyao , Ding Lijian , Li Weitao , Sun Wei , Li Qiyue
Published: December 2022

Automatically and accurately detecting the self‐blast state of glass insulators is of great significance to operation and maintenance of transmission lines. To solve the shortcomings of the existing open‐loop cognitive models to detect the self‐blast state of glass insulators, this study explores a mixed data augmentation‐based intelligent recognition method to detect the self‐blast state of the glass insulator, by imitating the human cognitive mode. Firstly, generative adversarial network is utilised to obtain the high‐quality generative self‐blast samples of the glass insulator, and the non‐generative data augmentation techniques is used to obtain rich sample features. Secondly, considering the characteristics of aerial images such as large scale variations, variable shooting angles and complex backgrounds, feature maps with strong semantics and adaptive multi‐scale fusion are extracted using the feature pyramid network with adaptive hierarchy and the multi‐deformable convolutional network. Then, the extracted feature maps are transmitted to a two‐dimensional stochastic configuration network that can adaptively generate hidden nodes and basis functions so as to develop the self‐blast state classification criteria with universal approximation capability. Thirdly, based on the generalised error and entropy theory, the semantic error entropy evaluation indices of recognition results are defined to evaluate in real time, the credibility of the uncertain recognition results for the self‐blast state of the glass insulator. Then, based on transfer learning and the established self‐optimising feedback mechanism for feature pyramid network, the self‐optimising adjustment and reconstruction of the feature map space with strong semantics and multi‐scale fusion and its classification criteria are realised. Finally, the stacking method is applied to integrate the recognition results of the feature pyramid network with adaptive hierarchy and multi‐channel deformable convolutional networks to improve the robustness of the recognition model. Results of experimental comparison with other machine learning and deep learning methods verify the feasibility and effectiveness of the proposed method.
Effect of radical scavenger on electrical tree in cross‐linked polyethylene with large harmonic superimposed DC voltage
Authors: Zhu Lewei , Li Zhonglei , Hou Kai
Published: December 2022

In this study, three kinds of radical scavenger Chimassorb 944, Tinuvin 622, and Tinuvin 770 are used to suppress the growth of electrical trees in cross‐linked polyethylene (XLPE) with transient superimposed voltage under the temperature gradient. The tree morphology, tree length, accumulated damage, and time to breakdown are used to investigate the effect of radical scavenger on the electrical treeing process. It is found that under the temperature gradient caused by the temperature rise on the high voltage side, only Tinuvin 622 can always suppress the electrical tree as the temperature gradient rises. Under the temperature gradient caused by the temperature rise on the ground side, the three radical scavengers can all suppress the electrical tree. The breakdown of electrical tree exhibits the strong DC polarity dependence. Meanwhile, energy levels of these three radical scavengers are calculated through quantum chemistry, and the results indicate that radical scavengers have greater electron affinity, smaller ionisation energy, and smaller energy gap than XLPE. According to the surface potential decay test results at 60°C, it is found that all three radical scavengers can introduce deep traps. The different performances of radical scavengers under different temperature gradients and voltages are determined by the trap distribution characteristics, the molecular structure and chemical reaction of the additives themselves. It is concluded that Tinuvin 622 has potential for use in high voltage direct current XLPE cable application.
Dual‐ and triple‐stream RESUNET/UNET architectures for multi‐modal liver segmentation
Authors: Elghazy Hagar Louye , Fakhr Mohamed Waleed
Published: December 2022

Deep learning image segmentation has become an important field of interest in recent years, especially when it comes to medical images. Segmentation of medical image modalities such as magnetic resonance imaging (MRI) and computed tomography (CT) can benefit diagnosis accuracy, speed up diagnosis process, and decrease workload. The most famously used deep learning models in the medical image segmentation are the UNET‐based models, which have been repeatedly proven to provide a high percentage of accuracy in medical image segmentation. But, most of the available datasets contain a single modality and thus are not big enough to train complex architectures. Lately, it has been shown that using multiple modalities with multiple streams architectures can provide higher accuracy more than single modality with a single stream architecture. In this paper, the benefits of dual‐stream and triple‐stream architectures are demonstrated when processing multiple modalities. This work shows that dual stream can achieve dice of 0.97 on CT images and 0.89 on MRI images, while in triple stream architectures can achieve dice of 0.97 on CT images and 0.96 on MRI images. To the best of our knowledge, these are the best results to date.
Synthetic aperture radar image despeckling using convolutional neural networks in wavelet domain
Authors: Liu Jing , Liu Runchuan
Published: December 2022

It is difficult for a convolutional neural network (CNN) to capture the detailed features of synthetic aperture radar (SAR) images when increasing the network depth. To capture sufficient information for reconstructing image details, the authors propose a multidirectional and multiscale convolutional neural network (MMCNN) in which the wavelet subband is input into each independent subnetwork to be trained. Each subnetwork has few convolution layers and a loss function. When the loss function reaches its optimal value, all subbands are integrated to produce the despeckled SAR image through the inverse Wavelet transform. The proposed MMCNN consisting of multiple subnetworks extracts the detailed features and suppresses speckle noise from different directions and scales; thus, its performance is improved by broadening the network width rather than increasing the depth. Experimental results on synthetic and real SAR images show that the proposed method shows superior performance over the state‐of‐the‐art methods in terms of both quantitative assessments and subjective visual quality, especially for strong speckle noise.
A CNN with noise inclined module and denoise framework for hyperspectral image classification
Authors: Gong Zhiqiang , Zhong Ping , Yao Wen , Zhou Weien , Qi Jiahao , Hu Panhe
Published: December 2022

Deep Neural Networks have been successfully applied in hyperspectral image classification. However, most of prior works adopt general deep architectures while ignore the intrinsic structure of the hyperspectral image, such as the physical noise generation. This would make these deep models unable to generate discriminative features and provide impressive classification performance. To leverage such intrinsic information, this work develops a novel deep learning framework with the noise inclined module and denoise framework for hyperspectral image classification. First, the spectral signature of hyperspectral image is modeled with the physical noise model to describe the high intra‐class variance of each class and great overlapping between different classes in the image. Then, a noise inclined module is developed to capture the physical noise within each object and a denoise framework is then followed to remove such noise from the object. Finally, the CNN with noise inclined module and the denoise framework is developed to obtain discriminative features and provides good classification performance of hyperspectral image. Experiments are conducted over two commonly used real‐world datasets and the experimental results show the effectiveness of the proposed method. The implementation of the proposed method and other compared methods could be accessed at https://github.com/shendu‐sw/noise‐physical‐framework.
Parking space inventory from above: Detection on aerial images and estimation for unobserved regions
Authors: Hellekes Jens , Kehlbacher Ariane , Díaz María López , Merkle Nina , Henry Corentin , Kurz Franz , Heinrichs Matthias
Published: December 2022

Parking is a vital component of today's transportation system and descriptive data are therefore of great importance for urban planning and traffic management. However, data quality is often low: managed parking places may only be partially inventoried, or parking at the curbside and on private ground may be missing. This paper presents a processing chain in which remote sensing data and statistical methods are combined to provide parking area estimates. First, parking spaces and other traffic areas are detected from aerial imagery using a convolutional neural network. Individual image segmentations are fused to increase completeness. Next, a Gamma hurdle model is estimated using the detected parking areas and OpenStreetMap and land use data to predict the parking area adjacent to streets. A systematic relationship is found between the road length and type and the parking area obtained. It is suggested that these results are informative to those needing information on parking in structurally similar regions.
Die Analyse von Schnarchen bei Patienten mit obstruktiver Schlafapnoe (OSA) anhand von Polysomnographie und LEOSound
Authors: Moaeri S. , Hildebrandt Olaf , Cassel W. , Viniol C. , Schäfer A. , Kesper K. , Sohrabi K. , Gross V. , Koehler Ulrich
Published: December 2022

Einleitung In dieser Studie wird bei Patienten mit OSA parallel zur Erfassung des Biosignals Schnarchen aus der Polysomnografie auch eine akustische Aufzeichnung mit dem LEOSound (akustische Langzeitregistrierung der Atem- und Atemnebengeräusche) durchgeführt. Es stellt sich die Frage, wie viele der obstruktiven Apnoen bei apnoeterminierender Wiederaufnahme der Atmung mit Schnarchen einhergehen.

Methode Parallel zur polysomnografischen Messung wurde bei 40 Patienten mit OSA (AHI > 15/h) eine Atem- und Atemnebengeräuschaufzeichnung mit dem LEOSound-Rekorder durchgeführt. Das durchschnittliche Alter der Patienten lag bei 57 ± 11 Jahren. Das durchschnittliche Körpergewicht betrug 100 ± 19 kg bei einem mittleren Body-Mass-Index (BMI) von 33 ± 7 kg/m2. 12 der 40 Aufzeichnungen mussten aufgrund qualitativ unzureichender Messqualität von der Bewertung ausgeschlossen werden. Die visuell detektierten Schnarchereignisse in der Polysomnografie wurden mit den audiovisuell erfassten im LEOSound verglichen.

Ergebnisse Insgesamt konnten 3778 obstruktive Apnoephasen registriert werden. In der Polysomnografie gingen 2229 (58,8%) Apnoen mit Schnarchen einher, in der akustischen Messung 1921 (51,0%). Bei einem der Patienten war eine ausgeprägtere Abweichung der Frequenz der Schnarchereignisse von PSG und LEOSound nachweisbar.

Diskussion Schnarchen wird in beiden Verfahren bei etwa 60% der obstruktiven Apnoephasen gefunden. Eine audiovisuelle Beurteilung von Schnarchen ist mittels Geräuschaufzeichnung sehr zuverlässig durchführbar. Es bedarf der weiteren Klärung, warum nur 60% der apnoeterminierenden Hyperpnoen mit Schnarchen einhergehen. Pathophysiologisch wäre zu erwarten, dass das Öffnen des obstruierten Atemwegs in einem sehr viel höheren Prozentsatz mit einer turbulenten Strömung, Weichteilschwingung und damit auch Schnarchen kombiniert ist.
Effektivität der Novafon Local Vibration Voice Therapy & Water Resistance Therapy: eine Meta-Analyse
Authors: Latoszek Ben Barsties v. , Hetjens Svetlana
Published: December 2022

Hintergrund Die Behandlungsansätze für die Stimmtherapie sind
vielfältig. Zwei neuere Behandlungsansätze in der Stimmtherapie mit Hilfsgeräten sollen auf
ihre Effektivität untersucht und verglichen werden. Die Auswertungen der Behandlungseffekte
verschiedener Ansätze sind wichtig für die klinische Beratung und die evidenzbasierte
Praxis.

Ziel Die Wirksamkeit der Novafon Local Vibration Voice Therapy
(NLVVT) und der Water Resistance Therapy (WRT) hinsichtlich der Bewertung mittels Voice
Handicap Index (VHI) und seinen Aspekten soll überprüft werden.

Design Systematische Literatursuche und Meta-Analyse mit
Random-Effects-Modell.

Datenquellen Die Auswertung der 2 Datenbanken (MEDLINE und
CENTRAL) und einer manuellen Suche von Beginn bis zum 19. September 2021.

Studienauswahl Jede klinische Gruppenstudie in einem
Prä-post-Design, die in englischer oder deutscher Sprache verfasst wurde und die Wirksamkeit
von NLVVT oder WRT mittels VHI (funktionelle [F], physische [P] und emotionale [E] Aspekte und
der Gesamtwert [T]) bei erwachsenen Stimmpatienten mit einer organischen oder funktionellen
Stimmstörung überprüft hat, wurde berücksichtigt.

Ergebnisse Fünf geeignete Studien wurden identifiziert (NLVVT n=
22; WRT n= 42). Beide Behandlungsansätze zeigten hochsignifikante Verbesserungen bei allen
Aspekten des VHI (p<0,01). Im direkten Vergleich erreichte NLVVT signifikant stärkere
Verbesserungen bei VHI-T, VHI-F und VHI-E als WRT (p<0,01). Vergleichbar war die
Verbesserung bei VHI-P (p=0,28).

Fazit Die subjektive Bewertung nach dem Voice Handicap Index
ergab, dass NLVVT und WRT effektive Behandlungsmethoden bei Stimmstörungen sind. Im direkten
Vergleich erreichte NLVVT in den meisten VHI-Aspekten stärkere Verbesserungen als WRT.
Systematic Review of Kangaroo Care Duration's Impact in Neonatal Intensive Care Units on Infant–Maternal Health
Authors: Clarke-Sather Abigail R. , Compton Crystal , Roberts Kari , Brearley Ann , Wang Sonya G.
Published: December 2022

Kangaroo care (KC), skin-to-skin contact between infants and caregivers, is encouraged in neonatal intensive care units (NICUs) to support health through improved weight, growth, and infant–maternal attachment while reducing the incidence of sepsis and infant pain. However, the optimal duration and frequency of KC to maximize health outcomes is unknown. Given parents' time stressors, identifying optimal KC time is critical. A literature review was undertaken on May 28, 2021 via querying the PubMed database from January 1, 1995, to May 28, 2021, regarding KC and NICUs with 442 results. Eleven studies met the eligibility criteria of (1) comparative KC between infants and adult caregivers in NICUs as a randomized controlled trial, (2) peer-reviewed articles in English, (3) study subjects ≥5, (4) health outcomes, and (5) KC sessions >1. Infant physical growth parameters, infant neurodevelopment, infant stress via salivary cortisol levels, and breastfeeding outcomes appear to increase with KC as compared with standard care (SC) without KC. Improvements were observed with longer KC duration, 2 h/d as compared with 1 h/d, for neurodevelopment and breastfeeding outcomes, but no greater improvement with longer KC duration was shown for reducing infant stress through salivary cortisol levels. Regarding maternal stress, the influence of KC duration showed mixed Parental Stressor Score: NICU scores. Further study on the impact of KC duration and frequency on health outcomes and dose–response relationship would help determine how much and how frequent KC is needed to improve specific health outcomes for infants and their mothers.

Key Points
Outcomes of Free Muscle Flaps versus Free Fasciocutaneous Flaps for Lower Limb Reconstruction following Trauma: A Systematic Review and Meta-Analysis
Authors: Dow Todd , ElAbd Rawan , McGuire Connor , Corkum Joseph , Youha Sarah Al , Samargandi Osama , Williams Jason
Published: December 2022

Background Free flap reconstruction of the lower limb following trauma often suffers higher complication rates than other areas of the body. The choice of muscle or fasciocutaneous free flap is an area of active debate.

Methods A systematic review of EMBASE, MEDLINE, PubMed, and Cochrane Register from inception to April 1, 2022 was performed. Articles were assessed using the methodological index for non-randomized studies instrument. The primary outcome was to assess and compare the major surgical outcomes of partial or total flap failure, reoperation, and amputation rates.

Results Seventeen studies were included. All studies were retrospective in nature, of level three evidence, and published between 1986 and 2021. The most common muscle and fasciocutaneous free flaps used were latissimus dorsi flap (38.1%) and anterolateral thigh (ALT) flap (64.8%), respectively. Meta-analysis found no significance difference in rates of total flap failure, takeback operations, or limb salvage, whereas partial flap failure rate was significantly lower for fasciocutaneous flaps. The majority of studies found no significant difference in complication rates, osteomyelitis, time to fracture union, or time to functional recovery. Most, 82.4% (14/17), of the included studies were of high methodological quality.

Conclusion The rate of total flap failure, reoperation, or limb salvage is not significantly different between muscle and fasciocutaneous free flaps after lower limb reconstruction following trauma. Partial flap failure rates appear to be lower with fasciocutaneous free flaps. Outcomes traditionally thought to be managed better with muscle free flaps, such as osteomyelitis and rates of fracture union, were comparable.
Immediate Intraoperative Microsurgical Repair of the Recurrent Laryngeal Nerve: A Fifteen-Year Institutional Experience
Authors: McGraw J Reed , Bascone Corey M. , Jaimez Ivan A. , Barrero Carlos E. , Fosnot Joshua , Fraker Douglas L. , Kovach Stephen J.
Published: December 2022

Background Recurrent laryngeal nerve (RLN) injury carries significant morbidity. Microsurgical repair of the RLN has proven promising for enhancing patient recovery of vocal function; however, data remains limited.

Methods This retrospective cohort study included patients who underwent RLN repair from 2007 to 2022. Demographics and medical history were collected. The location and etiology of RLN injury, as well as the repair technique, were collected. Follow-up data were collected at the initial postoperative visit, at 6 months and at 1 year. Hoarseness was classified as mild, moderate, or severe. Of patients who underwent nasopharyngolaryngoscopy (NPL) following repair, the glottic gap was measured. Vocal interventions performed were also recorded. This study utilized descriptive statistical methods.

Results Eleven patients underwent RLN repair. All patients underwent immediate repair. Fifty-four percent (n = 6) of RLN injuries resulted from tumor inflammation or nerve encasement. Eighty-two percent (n = 9) underwent direct RLN coaptation, 9% (n = 1) underwent vagus-RLN anastomosis, and 9% (n = 1) underwent an interposition nerve graft. Technical success was 100%. Seventy-three percent (n = 8) required otolaryngology referral, and of those, 50% (n = 4) required intervention. At initial evaluation, 91% (n = 10) suffered from mild to severe hoarseness, and of patients who underwent NPL, all had a glottic gap. At 1 year, 82% of patients (n = 9) improved to having mild to no appreciable hoarseness. Of the patients who underwent NPL, 62% (n = 5) had closure of the glottic gap.

Conclusion Patients undergoing repair of the RLN following injury showed excellent recovery of vocal function and resolution of glottic gap at 1 year.
Accuracy of a Clinical Applicable Method for Prediction of
VO2max Using Seismocardiography
Authors: Hansen Mikkel Thunestvedt , Husted Karina Louise Skov , Fogelstrøm Mathilde , Rømer Tue , Schmidt Samuel Emil , Sørensen Kasper , Helge Jørn
Published: December 2022

Cardiorespiratory fitness measured as ˙VO2max is considered an
important variable in the risk prediction of cardiovascular disease and
all-cause mortality. Non-exercise ˙VO2max prediction models
are applicable, but lack accuracy. Here a model for the prediction of
˙VO2max using seismocardiography (SCG) was investigated.
97 healthy participants (18–65 yrs., 51 females) underwent
measurement of SCG at rest in the supine position combined with demographic data
to predict ˙VO2max before performing a graded exercise test
(GET) on a cycle ergometer for determination of ˙VO2max using
pulmonary gas exchange measurements for comparison. Accuracy assessment revealed
no significant difference between SCG and GET ˙VO2max
(mean±95% CI; 38.3±1.6 and
39.3±1.6 ml·min−1·kg−1,
respectively. P=0.075). Further, a Pearson correlation of
r=0.73, a standard error of estimate (SEE) of
5.9 ml·min−1·kg−1,
and a coefficient of variation (CV) of 8±1% were found. The SCG
˙VO2max showed higher accuracy, than the non-exercise
model based on the FRIENDS study, when this was applied to the present
population
(bias=−3.7±1.3 ml·min−1·kg−1,
p<0.0001. r=0.70.
SEE=7.4 ml·min−1·kg−1,
and CV=12±2%). The SCG ˙VO2max
prediction model is an accurate method for the determination of
˙VO2max in a healthy adult population. However, further
investigation on the validity and reliability of the SCG
˙VO2max prediction model in different populations is needed
for consideration of clinical applicability.
Entropy from electrons in nanoscale systems
Authors: Piccone Ashley
Published: December 2022

Electronic measurements can determine entropy in quantum dots and single molecules — a measurement that has been historically difficult to perform.
Phase transitions in evolutionary dynamics
Authors: Scott Adam D. , King Dawn M. , Ordway Stephen W. , Bahar Sonya
Published: December 2022

Sharp changes in state, such as transitions from survival to extinction, are hallmarks of evolutionary dynamics in biological systems. These transitions can be explored using the techniques of statistical physics and the physics of nonlinear and complex systems. For example, a survival-to-extinction transition can be characterized as a non-equilibrium phase transition to an absorbing state. Here, we review the literature on phase transitions in evolutionary dynamics. We discuss directed percolation transitions in cellular automata and evolutionary models, and models that diverge from the directed percolation universality class. We explore in detail an example of an absorbing phase transition in an agent-based model of evolutionary dynamics, including previously unpublished data demonstrating similarity to, but also divergence from, directed percolation, as well as evidence for phase transition behavior at multiple levels of the model system's evolutionary structure. We discuss phase transition models of the error catastrophe in RNA virus dynamics and phase transition models for transition from chemistry to biochemistry, i.e., the origin of life. We conclude with a review of phase transition dynamics in models of natural selection, discuss the possible role of phase transitions in unraveling fundamental unresolved questions regarding multilevel selection and the major evolutionary transitions, and assess the future outlook for phase transitions in the investigation of evolutionary dynamics.
Progress and challenges in the development of ultra-wide bandgap semiconductor α-Ga2O3 toward realizing power device applications
Authors: Oshima Yuichi , Ahmadi Elaheh
Published: December 2022

Ultra-wide-bandgap (UWBG) semiconductors, such as Ga2O3 and diamond, have been attracting increasing attention owing to their potential to realize high-performance power devices with high breakdown voltage and low on-resistance beyond those of SiC and GaN. Among numerous UWBG semiconductors, this work focuses on the corundum-structured α-Ga2O3, which is a metastable polymorph of Ga2O3. The large bandgap energy of 5.3 eV, a large degree of freedom in band engineering, and availability of isomorphic p-type oxides to form a hetero p–n junction make α-Ga2O3 an attractive candidate for power device applications. Promising preliminary prototype device structures have been demonstrated without advanced edge termination despite the high dislocation density in the epilayers owing to the absence of native substrates and lattice-matched foreign substrates. In this Perspective, we present an overview of the research and development of α-Ga2O3 for power device applications and discuss future research directions.
High mobility achieved in InGaZnO TFT with vacuum-gap as insulating layer
Authors: Bai Ziheng , Zhao Ying , Wang Jiawei , Liu Dongyang , Shan Yu , Guo Zean , Kai Yuan , Hu Ke , Lu Congyan , Lu Nianduan , Xiao Kui , Li Ling
Published: December 2022

In this Letter, an amorphous In-Ga-Zn-O (InGaZnO) thin-film transistor (TFT) structure with a vacuum-gap as a dielectric layer is proposed and investigated. Field-effect conduction at the vacuum/InGaZnO interfaces exhibits extraordinary effective mobility (μ) up to 65 ± 20 cm2 V−1 s−1, while the μ is only around 10 cm2 V−1 s−1 at the SiO2/InGaZnO interfaces with similar film processing conditions. Temperature-dependent transport is performed for deeper insight of the physical origin of the much higher μ at the vacuum/InGaZnO interface. We have found the density of states (DOS) of tail states is notably lower for the transport near the vacuum (8 × 1017 compared to 1.1 × 1019 cm−3 eV−1 at the SiO2/vacuum interface). These indicate that traditional dielectric materials like SiO2 have strong effects on the charge transport degradation in InGaZnO TFTs by introducing extra energetic disorders, and the intrinsic charge transport in InGaZnO is potentially approaching those in poly-silicon TFTs. Exploring a high-quality dielectric layer should be one effective way to further optimize the electrical performance in TFTs based on amorphous oxide semiconductors.
Voltage control of magnetic properties in GdxFe100-x films by hydrogen migration
Authors: Xing Yuzhi , Xing Ruofei , Zhao Xiaonan , Wu Zhenfa , Wang Dong , Song Houning , Qi Chen , Wei Lin , Yan Shishen , Tian Yufeng , Bai Lihui , Chen Yanxue
Published: December 2022

Voltage control of magnetic properties is a promising path to realize low-power spintronic devices and meets the requirements for quicker information processing speed and ongoing scale reduction. Hydrogen migration induced by voltage gating has been demonstrated to modify the intrinsic magnetic properties of materials by affecting the exchange interaction, electron occupancy, and magnetoelastic effect. Herein, the magnetic properties of a ferrimagnetic Gd29Fe71 film in an all-solid-state multilayer device, which is constructed using a GdOx electrolyte, can be reversibly modulated by voltage-controlled hydrogen migration. Polar MOKE results indicate that hydrogen intercalation/deintercalation can modulate the Gd29Fe71 film's degree of compensation and control the dominant magnetic sublattice. Furthermore, the polarity of the polar MOKE curves can be reversibly switched. As with the increase in hydrogen loading, the compensation point in the Gd29Fe71 film is approached, the density of magnetic domain nucleation sites decreases, and the magnetic domain structures transform from labyrinth domains to uniform large area domains. At the same time, a strong perpendicular magnetic anisotropy is developed. This work shows a possible pathway for reversible control of magnetism in spintronic devices.
Role of morphology in defect formation and photo-induced carrier instabilities in amorphous indium oxide
Authors: Medvedeva Julia E.
Published: December 2022

Ab initio molecular dynamics liquid-quench simulations and hybrid density functional calculations are performed to model the effects of room-temperature atomic fluctuations and photo-illumination on the structural and electronic properties of amorphous sub-stoichiometric In2O2.96. A large configurational ensemble is employed to reliably predict the distribution of localized defects as well as their response to the thermal and light activation. The results reveal that the illumination effects on the carrier concentration are greater in amorphous configurations with shorter In–O bond length and reduced polyhedral sharing as compared to the structures with a more uniform morphology. The obtained correlation between the photo-induced carrier density and the reduction in the number of fully coordinated In-atoms implies that metal oxides with a significant fraction of crystalline/amorphous interfaces would show a more pronounced response to illumination. Photo-excitation also produces In–O2–In defects that have not been previously found in sub-stoichiometric amorphous oxides; these defects are responsible for carrier instabilities due to overdoping.
Symmetry-based identification and enumeration of independent tensor properties in nonlinear and chiral optics
Authors: Andrews David L.
Published: December 2022

For many laser-based methods of material characterization and analysis, a tensor formulation of theory is necessary, especially in techniques that exploit nonlinear or chiral optics. The fundamental interactions that underpin such methods offer various levels of approach to theory, but the most rigorous often lead to equations of considerable complexity. To compute the values for individual material parameters frequently demands making assumptions of extreme simplicity, overly dependent on calculational method, yet still providing unsatisfactory results. A pragmatic and entirely rigorous symmetry-based approach to the irreducible tensorial structures circumvents many of these problems, securing reliable results and guiding the pathway to applications. Instead of focusing on individual tensor components, such an approach can rapidly determine the number of linearly independent quantities—and hence the number of operationally different setups necessary for full characterization. By such means, one can directly ascertain how variations of optical polarization and beam geometry can reliably capture the response of any material system. The use of an irreducible tensor method operates independently of any means that might be chosen to calculate material properties. It removes the need for common simplifying assumptions, such as the approximation of tensorial structure by a scalar representation, adoption of a two-state model, or disregarding near-resonance damping. It also obviates any dependence on a choice of simulation package or quantum-calculational software. In this paper, the principles are set down and illustrated by application to experiments of varying degrees of complexity, including interactions of growing significance in the realm of chiral nonlinear optics. Limitations of this approach are also critically assessed.
Discovery of a new polymorph of clotrimazole through melt crystallization: Understanding nucleation and growth kinetics
Authors: Zhang Jie , Liu Minzhuo , Xu Meixia , Chen Zhiguo , Peng Xucong , Yang Qiusheng , Cai Ting , Zeng Zhihong
Published: December 2022

Clotrimazole (CMZ) is a classical antifungal drug for studying crystallization. In this study, a new CMZ polymorph (Form 2) was discovered during the process of nucleation and growth rate determination in the melt. High-quality single crystals were grown from melt microdroplets to determine the crystal structure by x-ray diffraction. Form 2 is metastable and exhibits a disordered structure. The crystal nucleation and growth kinetics of the two CMZ polymorphs were systematically measured. Form 2 nucleates and grows faster than the existing form (Form 1). The maximum nucleation rate of Forms 1 and 2 was observed at 50 °C (1.07 Tg). The summary of the maximum nucleation rate temperature of CMZ and the other six organic compounds indicates that nucleation near Tg in the supercooled liquid is a useful approach to discovering new polymorphs. This study is relevant for the discovering new drug polymorphs through an understanding of nucleation and growth kinetics during melt crystallization.
The interaction mechanism of photogenerated carriers and piezoelectric charges of a photoactive piezoelectric nanogenerator
Authors: Miao Kexin , Su Huanxin , Li Mingqing , Yao Hongbo , Zhang Yunchen , Wang Hao , Zhang Yaju , Yang Liya , Zheng Haiwu
Published: December 2022

Despite the fact that photoactive piezoelectric nanogenerators (PENGs) have been getting more attention due to their significant potential as a self-powered photodetector and pressure sensor, investigations on the interaction mechanism between photogenerated carriers and piezoelectric charges are still insufficient. In this study, photoactive PENGs based on methylammonium lead halides-poly(vinylidene) (MAPI-PVDF) composite were fabricated, in which the presence of MAPI in the PVDF matrix plays a dual role in enhancing the nucleation of the electroactive β-phase as well as inducing photoactivity in the composite. It has an optimal open-circuit voltage of 4.7 V and short-circuit current of 0.2 μA at 10 wt. % concentration of MAPI under illumination, which is nearly halved in the dark. Furthermore, we have thoroughly explored the interaction mechanism between photogenerated carriers and piezoelectric charges by piezoresponse scanning force microscopy techniques, photoluminescence spectroscopy, and a bandgap analysis. The results demonstrate that the photogenerated carriers screen part of the piezoelectric potential induced by the piezoelectric charges, while the piezoelectric charges promote more photogenerated carriers recombination. This work opens up horizons for the piezoelectric community in designing photoactive PENGs with multiple application modes and provides an effective approach to the development of piezoelectric materials.
Oscillating rheological behavior of Turbatrix aceti nematodes
Authors: Ali Nazim , Nand Sada , Kiran Abhimanyu , Mishra Manoranjan , Mehandia Vishwajeet
Published: December 2022

We present an experimental investigation of the rheological aspects of collective motion by the swimming Turbatrix aceti nematodes. We discover that these nematodes can significantly change the rheological properties of the suspension due to their body oscillations and form synchronized waves, which produce strong fluid flows. The strength of the collective state changes the shape of the interface where they swim in synchronization. We unravel that the effective viscosity of the nematode suspension at higher shear rates shows steady viscous behavior with time, where no significant effect of nematode activity is observed. For the first time, we have reported that at low shear rates, the activity effect is significant enough to generate oscillating viscous effects. In addition, we also measured the influence of the nematode concentration on suspension viscosity. This work opens a new way for understanding the rheological aspects of active matter under low and high shear rates. We illustrate these dynamics by showing that the force generated by these nematodes is sufficient to change the suspension rheology. The various aspects of nematodes, especially their large size and ease of culturing, make them a good model organism for experimental investigation as active fibers with oscillations. The oscillating behavior regulates the interfacial phenomenon and produces oscillatory rheological dynamics at low shear rates. The results of our work can be utilized to further study the novel metamaterials with negative viscosity, which have applications in healthcare and energy systems.
A revisit of Rayleigh capillary jet breakup at low Ohnesorge number
Authors: Gañán-Calvo Alfonso M.
Published: December 2022

The average Rayleigh capillary breakup length of a cylindrical Newtonian viscous liquid jet moving with homogeneous velocity must be determined by the selection of normal modes with time-independent amplitude and wavelength. Invariant modes (IMs) with both positive and negative group and phase velocities exist in ample ranges of the parameter domain (Weber and Ohnesorge), which explains (i) the self-sustained average breakup length (long-term resonance) and (ii) the governing role on breakup of both spatial growth rate and wave number of the dominant positive group velocity IM. Published experimental results at low Ohnesorge numbers confirm our proposal.
Cavitation inception and evolution in cavitation on a chip devices at low upstream pressures
Authors: Rokhsar Talabazar Farzad , Maleki Mohammadamin , Sheibani Aghdam Araz , Grishenkov Dmitry , Ghorbani Morteza , Koşar Ali
Published: December 2022

The concept of “hydrodynamic cavitation on a chip” offers facile generation of cavitating flows in microdomains, which can be easily scaled up by arranging short microchannels (micro-orifices) in cascade formations. In this regard, microscale cavitation in an energy-efficient test rig has the potential of increasing utilization possibilities of cavitation in a wide range of applications such as liquid-phase exfoliation. In this study, a new experimental test rig was constructed to generate microscale hydrodynamic cavitation. This setup enables cavitation bubble generation at low upstream pressures through the control of the downstream pressure of the device. Particular attention was directed to the classification of flow patterns, scale effects, and cavitating flow evolutions with an in-depth categorization of underlying mechanisms such as Kelvin–Helmholtz instability. Cavitation inception appeared in the form of a single bubble. The appearance of different attached cavitating flow patterns within the microfluidic device was accompanied by new physics, which revealed that cavitation generation and development are affected by the existence of various fluid flow phenomena, particularly the jet flow. The outcome of this study makes hydrodynamic cavitation on a chip attractive for applications, where the cavitation effects are sought in the presence of multiphase fluid flows.
Data-driven turbulence model for unsteady cavitating flow
Authors: Zhang Zhen , Wang Jingzhu , Huang Renfang , Qiu Rundi , Chu Xuesen , Ye Shuran , Wang Yiwei , Liu Qingkuan
Published: December 2022

Unsteady Reynolds-averaged Navier–Stokes (URANS) equations have been widely used in engineering fields to investigate cavitating flow owing to their low computational cost and excellent robustness. However, it is challenging to accurately obtain the unsteady characteristics of flow owing to cavitation-induced phase transitions. In this study, we propose an implicit data-driven URANS (DD-URANS) framework to analyze the unsteady characteristics of cavitating flow. In the DD-URANS framework, a basic computational model is developed by introducing a cavitation-induced phase transition into the equations of Reynolds stress. To improve the computational accuracy and generalization performance of the basic model, the linear and nonlinear parts of the anisotropic Reynolds stress are predicted through implicit and explicit methods, respectively. A data fusion approach, allowing the input and output of characterized parameters at multiple time points, is presented to obtain the unsteady characteristics of the cavitating flow. The DD-URANS model is trained using the numerical results obtained via large-eddy simulation. The training data consist of two parts: (i) the results obtained at cavitation numbers of 2.0, 2.2, and 2.7 for a Venturi flow, and (ii) those obtained at cavitation numbers of 0.8 and 1.5 for a National Advisory Committee for Aeronautics (NACA) 66 hydrofoil. The DD-URANS model is used to predict the cavitating flow at cavitation numbers of 2.5 for a Venturi flow and 0.8 for a Clark-Y hydrofoil. It is found that the DD-URANS model is superior to the baseline URANS model in predicting the instantaneous periodic shedding of a cavity and the mean flow fields.
Estimating random close packing in polydisperse and bidisperse hard spheres via an equilibrium model of crowding
Authors: Anzivino Carmine , Casiulis Mathias , Zhang Tom , Moussa Amgad Salah , Martiniani Stefano , Zaccone Alessio
Published: December 2022

We show that an analogy between crowding in fluid and jammed phases of hard spheres captures the density dependence of the kissing number for a family of numerically generated jammed states. We extend this analogy to jams of mixtures of hard spheres in d = 3 dimensions and, thus, obtain an estimate of the random close packing volume fraction, ϕRCP, as a function of size polydispersity. We first consider mixtures of particle sizes with discrete distributions. For binary systems, we show agreement between our predictions and simulations using both our own results and results reported in previous studies, as well as agreement with recent experiments from the literature. We then apply our approach to systems with continuous polydispersity using three different particle size distributions, namely, the log-normal, Gamma, and truncated power-law distributions. In all cases, we observe agreement between our theoretical findings and numerical results up to rather large polydispersities for all particle size distributions when using as reference our own simulations and results from the literature. In particular, we find ϕRCP to increase monotonically with the relative standard deviation, sσ, of the distribution and to saturate at a value that always remains below 1. A perturbative expansion yields a closed-form expression for ϕRCP that quantitatively captures a distribution-independent regime for sσ < 0.5. Beyond that regime, we show that the gradual loss in agreement is tied to the growth of the skewness of size distributions.
Modern Perspectives in the Study of Electronic Systems
Authors: Basu Saurabh , Chattopadhyay Sourav
Published: December 2022

Modern Perspectives in the Study of Electronic Systems focuses on recent developments in selected critical areas of condensed matter physics. The book blends theoretical developments and experimental discoveries of materials, helping the reader understand different phenomena. It studies the Quantum Hall Effect (integer and fractional) and superconductivity from phenomenological and microscopic perspectives. Magnetism and magnetic phenomena in solids via approximate solutions of the Hamiltonian model are also addressed. The book also discusses the topological aspects of materials that have fundamentally changed the study of condensed matter physics in the recent times.

This timely and practical book:Introduces topology that has governed the study of two-dimensional Dirac materials and led to the discovery of three-dimensional materialsIncludes illustrations and plots for better visualization and understanding of the book contentUses a hands-on approach to teach subjects that have influenced teaching and research worldwide

Modern Perspectives in the Study of Electronic Systems is an excellent tutorial for senior undergraduate students, graduate students, and early-career researchers. It will be helpful for teachers in teaching courses on specialized topics in condensed matter physics.
Symmetry and Topology
Authors: Basu Saurabh , Chattopadhyay Sourav
Published: December 2022

A pedagogical introduction to the discrete symmetries and the linkage between topology and condensed matter physics is discussed. To emphasize the concepts concretely, we have considered systems in one dimension (1D) and two dimensions (2D) only. In 1D, we study two paradigmatic models, namely, the Su-Schrieffer-Heeger (SSH) model and a Kitaev chain with p-wave-superconducting correlations. The topological phases are ascertained by computing the edge modes and the topological invariants, such as the winding number. The systems are shown to undergo phase transitions from topological to trivial phases via gap closing scenarios in the parameter space that define the Hamiltonians. In 2D, we study graphene and do a thorough check therein on the topological properties should there be a spectral gap at the Dirac points by computing the Berry phase etc and the existence of edge modes. Following Haldane’s conjecture of a chiral second neighbor complex hopping, we study the Haldane model and ascertain the topological properties by computing the Chern number, edge modes and anomalous Hall conductivity with a plateau of magnitude e2h near the zero bias. Finally, in a bid to restore the lost time reversal symmetry in the Haldane model, Kane and Mele proposed linking the electron spin to the Haldane flux, which gave rise to a new type of topological insulator that is characterized by a different topological invariant, known as the Z2 index. The phase thus obtained in the presence of Rashba spin-orbit coupling should be beneficial to the realization of spintronic devices. In the appendix, we provide a periodic table that lists the topological invariants based on symmetries present in different spatial dimensions.
Superconductivity
Authors: Basu Saurabh , Chattopadhyay Sourav
Published: December 2022

The history of the discovery of superconductivity and the salient features of superconductors, such as zero resistance, the Meissner effect, the specific heat discontinuity, etc. are discussed. Type-I and type-II superconductors are introduced along with their magnetic phase diagrams. Hence, we discuss the microscopic theory of superconductivity due to Bardeen, Cooper, and Schrieffer, the so called BCS theory which relies on the instability of a filled Fermi sea toward the formation of Cooper pairs, and the resultant Hamiltonian is solved via variational calculations on a paired many body state. We present an elaborate description of the BCS ground state, along with computing its key properties, such as, specific heat, expulsion of the electromagnetic field, the isotope effect, etc. A brief introduction to the phenomenological theory, namely, the Ginzburg-Landau theory, is presented thereafter. Furthermore, a finite momentum pairing state is discussed along with its possible experimental realization in heavy fermion and organic superconductors. Next, an account of the experimental methods for determining the spectral gap in superconductors is discussed. To compare and contrast with the findings of the BCS theory, two classes of unconventional superconductors, namely, the high-Tc cuprates and the iron-based pnictides and chalcogenides are discussed. The applications of superconductivity, such as the Josephson effect, and the properties of superconductor-based junctions, namely, the SQUIDs, are presented. Finally, a brief account of the Fermi liquid theory, which lies at the heart of microscopic superconductivity, is included in the appendix with an aim to point out the bottlenecks in explaining the unconventional normal state in cuprates and iron-based superconductors.