bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternative stopping rules to limit tree expansion for random forest models
Authors: Little Mark P. , Rosenberg Philip S. , Arsham Aryana
Published: September 2022

Random forests are a popular type of machine learning model, which are relatively robust to overfitting, unlike some other machine learning models, and adequately capture non-linear relationships between an outcome of interest and multiple independent variables. There are relatively few adjustable hyperparameters in the standard random forest models, among them the minimum size of the terminal nodes on each tree. The usual stopping rule, as proposed by Breiman, stops tree expansion by limiting the size of the parent nodes, so that a node cannot be split if it has less than a specified number of observations. Recently an alternative stopping criterion has been proposed, stopping tree expansion so that all terminal nodes have at least a minimum number of observations. The present paper proposes three generalisations of this idea, limiting the growth in regression random forests, based on the variance, range, or inter-centile range. The new approaches are applied to diabetes data obtained from the National Health and Nutrition Examination Survey and four other datasets (Tasmanian Abalone data, Boston Housing crime rate data, Los Angeles ozone concentration data, MIT servo data). Empirical analysis presented herein demonstrate that the new stopping rules yield competitive mean square prediction error to standard random forest models. In general, use of the intercentile range statistic to control tree expansion yields much less variation in mean square prediction error, and mean square prediction error is also closer to the optimal. The Fortran code developed is provided in the Supplementary Material.
Influence of growth rates, microstructural properties and biochemical composition on the thermal stability of mycelia fungi
Authors: Chulikavit Nattanan , Huynh Tien , Dekiwadia Chaitali , Khatibi Akbar , Mouritz Adrian , Kandare Everson
Published: September 2022

Mycelium fungal species exhibit fire retardant characteristics. The influence of the growth media on the fungal growth rates, biochemical composition, and microstructural characteristics and their relationship to thermal properties is poorly understood. In this paper, we demonstrate that molasses can support the growth of non-pathogenic Basidiomycota phylum fungal species producing bio-derived materials with potential fire retardation characteristics. Scanning electron microscopy and Fourier transform infrared (FTIR) spectrometry were used to interrogate the microstructural and biochemical properties of the molasses-grown mycelia species. Thermal decomposition of molasses-fed mycelia was evaluated via thermogravimetric analysis interfaced with FTIR for real-time evolved gas analysis. The morphological and microstructural characteristics of the residual char post-thermal exposure were also evaluated. The material characterization enabled the establishment of a relationship between the microstructural, biochemical properties, and thermal properties of molasses-fed mycelia. This paper presents a comprehensive exploration of the mechanisms governing the thermal degradation of three mycelial species grown in molasses. These research findings advance the knowledge of critical parameters controlling fungal growth rates and yields as well as how the microstructural and biochemical properties influence the thermal response of mycelia.
Topological state transfer in Kresling origami
Authors: Miyazawa Yasuhiro , Chen Chun-Wei , Chaunsali Rajesh , Gormley Timothy S. , Yin Ge , Theocharis Georgios , Yang Jinkyu
Published: September 2022

Topological mechanical metamaterials have been widely explored for their boundary states, which can be robustly isolated or transported in a controlled manner. However, such systems often require pre-configured design or complex active actuation for wave manipulation. Here, we present the possibility of in-situ transfer of topological boundary modes by leveraging the reconfigurability intrinsic in twisted origami lattices. In particular, we employ a dimer Kresling origami system consisting of unit cells with opposite chirality, which couples longitudinal and rotational degrees of freedom in elastic waves. The quasi-static twist imposed on the lattice alters the strain landscape of the lattice, thus significantly affecting the wave dispersion relations and the topology of the underlying bands. This in turn facilitates an efficient topological state transfer from one edge to the other. This simple and practical approach to energy transfer in origami-inspired lattices can thus inspire a new class of efficient energy manipulation devices.
Exploring the molecular landscape of multicomponent crystals formed by naproxen drug and acridines
Authors: Mirocki Artur , Lopresti Mattia , Palin Luca , Conterosito Eleonora , Sikorski Artur , Milanesio Marco
Published: September 2022

Three cocrystals were obtained by naproxen and acridines, optimizing the yield to more than 99% with LAG. The two structures by solution show a host-guest structure, while that by LAG a layered one, with no interconversion between parent structures.
Facile synthesis of a 2D multilayer core–shell MnO2@LDH@MMT composite with a nanoflower shape for electromagnetic wave absorption
Authors: Zhou Quan , Dai Xingjian , Li Kailin , Zhang Chenzhi , Zhang Xinfang , Du Zhilan , Yi Shuang , Yang Pingan , Rao Jinsong , Zhang Yuxin
Published: September 2022

Manganese dioxide@NiFe layered double hydroxide@montmorillonite (MNFM) with a nanoflower-like two-dimensional layered core–shell construction has been successfully synthesized by a two-step hydrothermal method.
Self-aggregation, H-bonding, and photoresponse in film and solution states of azobenzene containing polyurea
Authors: Erekath Swathi , Chordiya Kalyani , Vidhya K. V. , Kahaly Mousumi Upadhyay , Kalpathy Sreeram K.
Published: September 2022

Photoisomerization, aggregation, and UV-visible absorbance of cis and trans azo-polyurea thin films and solution are investigated. Hydrogen bonding and changes in excitation energies render cis azo-PU more stable in solution than in the film state.
Structural, electronic and catalytic properties of AgnSnn(n= 2–14) clusters by density functional theory
Authors: Yang Shu , Li Wei , Li YiFu , Chen XiuMin , Zhang Huan , Xu Baoqaing , Yang Bin
Published: September 2022

Density functional theory (DFT) calculations revealed that the catalytic performance of silver clusters for the oxidation of carbon monoxide can be improved by adding an equal amount of tin atoms to small-molecule silver clusters.
Exploring the defect equilibrium and charge transport in electrode material La0.5Sr0.5Fe0.9Mo0.1O3−δ
Authors: Markov A. A. , Nikitin S. S. , Merkulov O. V. , Patrakeev M. V.
Published: September 2022

Phase transformation in air and change in the concentration of molybdenum cations.
Polaron formation and transport in Bi2WO6 studied by DFT+U and hybrid PBE0 functional approaches
Authors: Tao Junyan , Zhang Qingyan , Liu Taifeng
Published: September 2022

A 2-dimensional (2D)-shaped electron polaron forming in B2WO6 or W-based materials with approximately 50% of the polaron density state localized on the central W site.
Electric field-induced switching of anomalous Nernst conductivity in the 2D MoTe2/VSe2 heterostructure
Authors: Marfoua Brahim , Hong Jisang
Published: September 2022

The 2D MoTe2/VSe2 heterostructure shows a large ANC of 2.3 A K−1 m−1 when the electric field was applied from the VSe2 to MoTe2 layers and switches to −0.6 A K−1 m−1 with an opposite electric field.
Insights into the different mechanistic stages of light-induced hydrogen evolution of a 5,5′-bisphenanthroline linked RuPt complex
Authors: Lämmle Martin , Pilz T. David , Kutta Roger Jan , Müßler Marius , Mengele Alexander K. , Görls Helmar , Heinemann Frank W. , Rau Sven
Published: September 2022

The fate of a catalyst: a dinuclear photocatalyst containing orthogonally oriented binding sites for chromophoric and catalytic metal centres changes the mechanism of light-driven hydrogen evolution from a molecular to a colloid-driven process.
A mechanistic study of the dopant-induced breakdown in halide perovskites using solid state energy storage devices
Authors: Mathieson Angus G. M. , Dose Wesley M. , Steinrück Hans-Georg , Takacs Christopher J. , Feldmann Sascha , Pandya Raj , Merryweather Alice J. , Mackanic David , Rao Akshay , Deschler Felix , De Volder Michael
Published: September 2022

Elucidating and quantifying the effects of doping on halide perovskites using lithium ion batteries.
Spiers Memorial Lecture: Next generation chalcogenide-based absorbers for thin-film solar cells
Authors: Mitzi David B. , Kim Yongshin
Published: September 2022

The lecture focuses on emerging chalcogenide-based thin-film photovoltaics and provides both an overview of selected absorber candidates that are of recent interest, and a deeper dive into an exemplary Cu2BaSn(S,Se)4-related family.
Direct photolysis of 4-tert-alkyl-1,4-dihydropyridines under blue-light irradiation for the generation of tertiary alkyl radicals
Authors: Gallage Prasadi C. , Pitre Spencer P.
Published: September 2022

4-tert-Alkyl-dihydropyridines can serve as tertiary radical precursors under visible-light irradiation in the absence of exogeneous photocatalysts or oxidants.
Spatiotemporal dynamic characterization of the laser-induced plasma of a mixed material (WCCu) under variable ablation angles in a vacuum
Authors: Wu Huace , Li Cong , Wu Ding , Liu Shiming , Hu Zhenhua , Feng Chunlei , Hai Ran , Ding Fang , Luo Guangnan , Ding Hongbin
Published: September 2022

In this paper, a LIBS system with a coaxial collection configuration is developed to investigate the spatiotemporal dynamic features of a laser-induced tungsten carbide copper (WCCu) plasma at variable LAAs under simulated EAST vacuum conditions.
Surfactant-laden droplet size prediction in a flow-focusing microchannel: a data-driven approach
Authors: Chagot Loïc , Quilodrán-Casas César , Kalli Maria , Kovalchuk Nina M. , Simmons Mark J. H. , Matar Omar K. , Arcucci Rossella , Angeli Panagiota
Published: September 2022

Improving surfactant-laden microdroplet size prediction using data-driven methods.
Simultaneous quantification of blood rheology and oxygen saturation to evaluate affinity-modifying therapies in sickle cell disease
Authors: Hansen Scott , Wood David K.
Published: September 2022

Sickle cell blood flow and hemoglobin oxygen saturation can be simultaneously measured using a microfluidic device. This combined measurement platform provides a tool to evaluate the potential clinical benefit of anti-sickling therapies.
Combinatorial screening SlipChip for rapid phenotypic antimicrobial susceptibility testing
Authors: Li Xiang , Liu Xu , Yu Ziqing , Luo Yang , Hu Qixin , Xu Zhenye , Dai Jia , Wu Nannan , Shen Feng
Published: September 2022

A combinatorial-screening SlipChip based on a self-partitioning mechanism performs high-throughput phenotypic AST with a panel of antibiotics and antibiotic combinations in three hours by monitoring the phenotypic profile of bacterial growth.
Transparent thermal insulation ceramic aerogel materials for solar thermal conversion
Authors: An Lu , Li Zheng , Guo Zipeng , Hu Yong , Huang Yulong , Armstrong Jason N. , Zhou Chi , Ren Shenqiang
Published: September 2022

Transparent ceramic aerogel materials toward emerging energy-efficient solar thermal window technologies.
Nano-NiCuZnCo2O4: a promising catalyst for the fast thermal decomposition of ammonium nitrate (AN) in an energetic formulation
Authors: Dave Pragnesh N , Sirach Ruksana
Published: September 2022

Ammonium nitrate (AN) decomposition has been investigated using a metal cobaltite catalyst, NiCuZnCo2O4. Pure AN decomposed (Td) at ∼563 K, while in the presence of nano-NiCuZnCo2O4 the decomposition temperature decreased by ∼40 K.
Reversible thermochromism to tune the bandgap of organic–inorganic hybrid materials
Authors: Wan Min , Chen Hao-Ran , Wang Yan-Ning , Shi Ke , Liu Jing-Yuan , Li Zi-Mu , Ye Si-Yu , Li Jun-Yi , Chen Li-Zhuang
Published: September 2022

Here, we report a series of organic–inorganic hybrid halide materials, with rare and fully reversible thermochromism, narrow bandgaps, and near-infrared luminescence. Thermochromism induced bandgap narrowing provide new insights for the further of organic–inorganic hybrid materials.
Ceruloplasmin in flatland: the relationship between enzyme catalytic activity and surface hydrophilicity
Authors: Kowalczyk Agata , Yu Cong , Nowicka Anna M.
Published: September 2022

Surface hydrophilicity – the way to control the activity of the immobilized enzyme.
3D printed tetrakis(triphenylphosphine)palladium (0) impregnated stirrer devices for Suzuki–Miyaura cross-coupling reactions
Authors: Penny Matthew R. , Rao Zenobia X. , Thavarajah Rumintha , Ishaq Ahtsham , Bowles Benjamin J. , Hilton Stephen T.
Published: September 2022

In a novel approach, SLA 3D-printed Pd(PPh3)4 containing stirrer beads have been used to catalyse the Suzuki–Miyaura reaction between a range of substrates.
Autothermal CO2 hydrogenation reactor for renewable natural gas generation: experimental proof-of-concept
Authors: Zhuang Yichen , Simakov David S. A.
Published: September 2022

94% CO2 conversion and 100% formation selectivity to CH4 are obtained in a laboratory Sabatier reactor with a packed bed, air-cooled configuration, using a commercial Ni catalyst.
Mechanistic insight into electrocatalytic glyoxal reduction on copper and its relation to CO2 reduction
Authors: Reichert Andreas M. , Piqué Oriol , Parada Walter A. , Katsounaros Ioannis , Calle-Vallejo Federico
Published: September 2022

Glyoxal is not likely a key intermediate of CO2 reduction to C2 species, but its electroreduction on Cu yields the commodity chemicals ethylene glycol and ethanol, produced at Cu terraces and defects, respectively.
Decoupling the impact of bulk and surface point defects on the photoelectrochemical properties of LaFeO3 thin films
Authors: Sun Xin , Tiwari Devendra , Li Meicheng , Fermin David J.
Published: September 2022

This article shows, for the first time, the delicate balance between controlling bulk recombination sites and dynamics of interfacial carrier transfer via independently tuning the bulk and surface compositions of perovskite oxide thin films.
Direct growth and post-treatment of zeolitic imidazolate framework-67 on carbon paper: an effective and stable electrode system for electrocatalytic reactions
Authors: Nguyen Anh Ngoc , Tran Ngoc Minh , Yoo Hyojong
Published: September 2022

Co-based MOFs are directly grown using an electrodeposited layer of Co(OH)2 on carbon paper and converted to cobalt sulfide (CoxSy) through a post-treatment process. The final electrode system exhibits remarkable oxygen evolution reaction performance.
Combinatorial approaches for mitigating resistance to KRAS-targeted therapies
Authors: Warren Hannah R. , Ross Sarah J. , Smith Paul D. , Coulson Judy M. , Prior Ian A.
Published: September 2022

Approximately 15% of all cancer patients harbor mutated KRAS. Direct inhibitors of KRAS have now been generated and are beginning to make progress through clinical trials. These include a suite of inhibitors targeting the KRASG12C mutation commonly found in lung cancer. We investigated emergent resistance to representative examples of different classes of Ras targeted therapies. They all exhibited rapid reactivation of Ras signaling within days of exposure and adaptive responses continued to change over long-term treatment schedules. Whilst the gene signatures were distinct for each inhibitor, they commonly involved up-regulation of upstream nodes promoting mutant and wild-type Ras activation. Experiments to reverse resistance unfortunately revealed frequent desensitization to members of a panel of anti-cancer therapeutics, suggesting that salvage approaches are unlikely to be feasible. Instead, we identified triple inhibitor combinations that resulted in more durable responses to KRAS inhibitors and that may benefit from further pre-clinical evaluation.
Internet of Things‐based smart insect monitoring system using a deep neural network
Authors: Wang JiangTao , Bu Yufei
Published: September 2022

According to recent studies, insects make up the vast majority of all animal species on the planet, and their numbers are rapidly dwindling. This occurrence has been recorded by a variety of insect taxa and geographic locales, but there is insufficient data to identify its true extent. Most monitoring methods are ineffective and time‐consuming, making insect population analysis difficult. Computer vision and deep learning advancements, on the other hand, may soon give new answers to this global challenge. Using cameras and other sensors, entomologists can gather data continuously and non‐invasively at any time of day or season. To capture specimens' physical appearance, automated imaging can be utilised in the laboratory. This data can be used to build a deep learning model to predict the quantity, biomass, and variety of insects. Additionally, deep learning models can measure the variability of phenotypic features, behaviour, and interactions. We may thank current advances in deep learning and computer vision for the immediate demand for more cost‐effective insect and invertebrate monitoring systems. Insect monitoring using sensors is demonstrated. Here, we show how deep‐learning algorithms might extract ecological information from massive data sets, and we explore the challenges ahead. There are four areas that will help us achieve our goal: There is a need for verification of taxonomic identification using pictures; sufficient training data; public reference databases; and ways for integrating molecular and deep learning technology.
Mining regular behaviors based on spatiotemporal trajectory multi‐dimensional features
Authors: Jiang Qiaowen , Liu Yu , Wang Bencai , He Qifang , Zhang Caisheng , Ding Ziran , Jian Tao
Published: September 2022

In the military and civilian surveillance domain, it is of great significance to mine regular behaviours of targets for situation awareness and command decision support. Most of the existing trajectory clustering algorithms only consider the similarity of spatial position of the trajectory, without sufficient multi‐dimensional information such as time, course and velocity. Some approaches based on information fusion take these multi‐dimensional information into account, but the features with different dimensions fused by weight coefficients are not robust and universal for different scenarios. In this paper, a regular behaviour mining method based on spatiotemporal trajectory multi‐dimensional features and density clustering is proposed. Firstly, multi‐dimensional Hausdorff similarity is defined to measure spatiotemporal trajectory from different feature dimensionalities. Different from methods based on information fusion, the proposed method defines trajectory density in feature similarity of different dimensions and adaptively determines parameters according to feature distribution in different dimensions. Experimental results in simulated and radar measured trajectory data show that the proposed method can be accurate and robust in clustering evaluation indexes such as Purity, Precision, Recall and Rand Index from different scenarios, which has a good application prospect in intelligent surveillance tasks.
Inhalative Therapie chronischer Erkrankungen der unteren Atemwege bei Hund und Katze – eine Literaturübersicht
Authors: Klenk Friederike K. , Schulz Bianka
Published: September 2022

Chronische Atemwegserkrankungen sind prävalente Krankheiten bei Hunden und Katzen, die meist einer lebenslangen Therapie bedürfen. Grundpfeiler vieler chronisch-entzündlicher Atemwegserkrankungen stellen Glukokortikoide dar. Zum Teil wird die Therapie zur besseren Symptomkontrolle zusätzlich durch Bronchodilatatoren ergänzt.

Aufgrund des erfolgreichen Einsatzes inhalativer Glukokortikoide in der Humanmedizin und der damit verbundenen Verringerung systemischer Nebenwirkungen, gewinnt auch in der Tiermedizin die Inhalationstherapie zunehmend an Bedeutung. Hierzu werden bei Hund und Katze vor allem Inhalationskammern (engl. „Spacer“ oder „Valved Holding Chambers“) in Kombination mit Dosieraerosolen verwendet. Die technischen Eigenschaften dieser Geräte sowie ihre Handhabung und Instandhaltung werden im Folgenden aufgezeigt. Darüber hinaus soll die aktuelle Studienlage zur Anwendung und Wirksamkeit inhalativer Präparate zur Therapie chronischer Atemwegserkrankungen bei Hunden und Katzen in folgendem Artikel zusammengefasst werden.
Free-Radical-Involved Trifluoromethylthiolation Cyclization of Alkenes To Access SCF3-Substituted Indolo[2,1-a]isoquinolines
Authors: Li Lijun , Liu Zhong-Quan , Li Zejiang , Li Yang , Yan Qinqin , Ren Yingming , Li Xuan
Published: September 2022

Free-radical-promoted tandem trifluoromethylthiolation of alkenes with AgSCF3, which provides an efficient protocol for the construction of SCF3-modified indolo[2,1-a]isoquinolines with moderate to good yields. A series of scaled-up experiments, other substrate transformations, and radical inhibition experiments were operated to verify the merit of this reaction system.
Traumatic Atlanto-occipital Dislocation in Children Followed by Hydrocephalus – A Case Report and Literature Review
Authors: Formentin Cleiton , Santos Lucas de Souza Rodrigues dos , Maeda Fernando Luis , Tedeschi Helder , Ghizoni Enrico , Joaquim Andrei F.
Published: September 2022

Traumatic atlanto-occipital dislocation (TAOD) are uncommon injuries associated with high immediate mortality rate and occurs more than twice in children than adults, due to biomechanical properties and immaturity of children's cervical spine. We report a pediatric patient with TAOD, who underwent occipitocervical stabilization and also developed a late hydrocephalus requiring a shunt procedure. A six-year-old boy was admitted to the emergency department after a car accident with refractory cervical pain. A cervical computed tomography (CT) scan showed an anterior C1–C2 level hematoma, and a dynamic CT scan demonstrated an increasing basion-dens interval on extension. Cervical magnetic resonance imaging (MRI) showed discontinuity of the tectorial membrane and diffused hyperintense signal on the left alar ligament. These findings were attributed to TAOD, and an occipitocervical fusion was performed. The pain and neurological status improved after surgery, but after 3 months he returned with persistent vomiting, headache, and a CT scan showing hydrocephalus. Then, a ventriculoperitoneal shunt was performed, improving the symptoms. One year after the injury, the patient remained asymptomatic, and a later radiography demonstrated satisfactory bone fusion. In conclusion, the decision-making process regarding treatment should consider several clinical and radiographic findings. Occipitocervical fusion is the treatment of choice, while hydrocephalus is not an unusual complication in children.
Supercanonical coordinates for orthosymplectic evolution operators
Authors: Anzaldo-Meneses A.
Published: September 2022

A time-dependent self-adjoint even Hamiltonian is defined by a linear combination of generators of the semidirect sum osp(m′/n′)⊕sne(n′+1), of the orthosymplectic plus the even Heisenberg algebra by computing the supercommutator of odd binary forms Π, given as linear combinations of odd bilinear generators of the odd Heisenberg algebra no(m′+1) elements times ne(n′+1) elements, establishing a relationship between entangled boson systems and entangled fermion systems. This approach leads to the concept of intertwining, defined through the resulting quadratic Hamiltonians of bosons and, separately, of fermions with coefficients given in terms of the same coefficients of Π. Intertwining is invariant under transformations of Π, which leave certain binary forms of the coefficients of Π in the Hamiltonian unchanged. Alternatively, the coefficients can be interpreted as simultaneous time-dependent (super-) control parameters for both spin-statistics. Time-dependent inhomogeneous linear supercanonical transformations of wave vectors leave invariant the Heisenberg superalgebra n(m′/n′) and belong to the semidirect product Osp(m′/n′) ⋉ Ne(n′ + 1) of the orthosymplectic supergroup with the even Heisenberg group. The unitary time evolution operator is constructed using the adjoint map in canonical coordinates determined by the supercanonical transformation. The method is a generalization of an Inönu–Wigner contraction procedure and a Wei–Norman method for superalgebras with a selection of subalgebras associated with the root space decomposition of the Lie superalgebra. Analogously, this is a separation of variables method for quantum mechanical problems in systems with bosons and fermions. The standard Floquet theory leads to new results concerning stability for locally periodic coefficients. The lowest dimensional cases are explicitly computed. The intertwining of boson and fermions systems and the Hamiltonians considered here are of interest in quantum control theory for systems including fermions and bosons, in quantum optics, and quantum computation.
Correlations between local electrocaloric effect and domains in ferroelectric crystals
Authors: Lei Chi Hou , Liu Yunya
Published: September 2022

Correlations between the local electrocaloric responses and the domains are critical to understanding the mechanisms of electrocaloric effect and, thus, enhancing the electrocaloric responses in ferroelectrics, which have not been explored. Combining phase-field simulations and entropy analysis, we establish the correlations between local electrocaloric responses and domains for ferroelectric crystals and investigate the local electrocaloric responses in different domain structures. The results reveal that both initial 180° and 90° domain walls (referring to stable domain walls before electric excitation) exhibit large positive electrocaloric responses due to the increased polarization under the applied electric field, where the responses of the initial 180° domain walls are more significant. The final 180° domain walls (referring to stable domain walls after electric excitation) show large negative electrocaloric responses, since the polarization changes from nonzero to zero under the applied electric field. Good agreement between simulations and experimental measurements is observed. In addition, as the domain wall density increases, the macroscopic average electrocaloric response can be enhanced multiplicatively, suggesting that increasing domain wall density is an alternative pathway to enhance electrocaloric response in ferroelectrics.
Enhanced scintillation performance of β-Ga2O3 single crystals by Al3+ doping and its physical mechanism
Authors: Li Zhiwei , Tang Huili , Li Yang , Gu Mu , Xu Jun , Chen Liang , Liu Jinliang , Ouyang Xiaoping , Liu Bo
Published: September 2022

β-Ga2O3 is a potential fast semiconductor scintillator with no significant self-absorption and excellent stability. However, the relatively low light yield of β-Ga2O3 at room temperature limits its practical application. In order to improve its scintillation performance, Al3+ doped β-Ga2O3 single crystals are investigated. By doping 5%Al3+ (atomic concentration), the light yield of β-Ga2O3 is increased from 4394 to 6816 ph/MeV. The increased light yield may be attributed to the decreased free electron concentration and inhibition of Auger nonradiative recombination. The thermal quenching effect can also be moderated by the increase in the thermal activation energy induced by Al3+ doping. The results indicate that Al3+ doping is an effective method to increase the light yield of β-Ga2O3.
Programmable bulk modulus in acoustic metamaterials composed of strongly interacting active cells
Authors: Kovacevich Dylan A. , Popa Bogdan-Ioan
Published: September 2022

Active acoustic metamaterials are one path to acoustic properties difficult to realize with passive structures, especially for broadband applications. Here, we experimentally demonstrate a 2D metamaterial composed of coupled sensor-driver unit cells with effective bulk modulus (κeff) precisely tunable through adjustments of the amplitude and phase of the transfer function between pairs of sensors and drivers present in each cell. This work adopts the concepts of our previous theoretical study on polarized sources to realize acoustic metamaterials in which the active unit cells are strongly interacting with each other. To demonstrate the capability of our active metamaterial to produce on-demand negative, fractional, and large κeff, we matched the scattered field from an incident pulse measured in a 2D waveguide with the sound scattered by equivalent continuous materials obtained in numerical simulations. Our approach benefits from being highly scalable, as the unit cells are independently controlled and any number of them can be arranged to form arbitrary geometries without added computational complexity.
Microflows in two-generation alveolar cells at an acinar bifurcation
Authors: Yang Yue , Bai Weitao , Dong Jun , Lv Huimin , Zhu Yonggang
Published: September 2022

The alveolus is a basic functional unit of the human respiratory system, and the airflow in the alveoli plays an important role in determining the transport and deposition of particulate matter, which is crucial for inhaled disease diagnosis and drug delivery. In the present study, taking advantage of the precise control ability of the microfluidic technique, a rhythmically expanding alveolar chip with multiple alveoli in two generations is designed and both the geometric and kinematic similarities are matched with the real human respiration system. With the help of a micro-PIV measurement system, the microflow patterns inside each alveolus can be studied. The observed vortex and radial flow patterns and the discovery of stagnant saddle points are similar to those captured in our previous platform with only one alveolus [Lv et al., Lab Chip 20, 2394–2402 (2020)]. However, the interactions between multiple alveoli also uncover new phenomena, such as the finding of stagnant saddle points in non-vortex flow patterns and significant differences in the flow pattern around the points between the time of T/4 and 3T/4. The obtained results could enrich the understanding of microflow in a whole alveolar tree with multiple generations.
Space-charge domains in n-type GaN epilayers under pulsed electric field
Authors: Balagula Roman M. , Subačius Liudvikas , Jorudas Justinas , Prystawko Paweł , Grabowski Mikołaj , Leszczyński Michał , Kašalynas Irmantas
Published: September 2022

Formation and drift of space-charge domains with velocity of sound were experimentally observed in charge current traces of a high-quality lightly doped GaN semiconductor under pulsed electric fields at room and liquid nitrogen temperatures. A GaN epilayer was developed on an Ammono GaN substrate to achieve the electron density and low-field mobility values of 1.06 × 1016 cm−3 and 1021 cm2/V s (at 300 K) and 0.21 × 1016 cm−3 and 2652 cm2/V s (at 77 K), respectively. The formation of moving space-charge domains was observed only in samples with the lengths of 1 mm and longer arising at the critical electric fields starting from ∼0.4 and ∼0.8 kV/cm at 77 and 300 K, respectively. Basic electron transport parameters were found investigating short samples with the lengths of 65 μm and shorter in a wide range of electric fields up to 150 kV/cm, at which the thermal material breakdown occurred. The critical length of a sample for space-charge domain formation was estimated considering the acoustoelectric effects in analysis of pulsed current–voltage characteristics, thus defining the constraints for the design of GaN-based power electronic devices.
Vacancy diffusion on a brominated Si(100) surface: Critical effect of the dangling bond charge state
Authors: Pavlova T. V. , Shevlyuga V. M.
Published: September 2022

Silicon dangling bonds (DBs) on an adsorbate-covered Si(100) surface can be created in a scanning tunneling microscope (STM) with high precision required for a number of applications. However, vacancies containing DBs can diffuse, disrupting precisely created structures. In this work, we study the diffusion of Br vacancies on a Si(100)-2 × 1-Br surface in an STM under typical imaging conditions. In agreement with previous work, Br vacancies diffuse at a positive sample bias voltage. Here, we demonstrated that only vacancies containing a positively charged DB hop across the two atoms of a single Si dimer, while vacancies containing neutral and negatively charged DBs do not. Calculations based on density functional theory confirmed that positively charged Br (and Cl) vacancies have a minimum activation barrier. We propose that diffusion operates by both one-electron and two-electron mechanisms depending on the applied voltage. Our results show that the DB charge has a critical effect on the vacancy diffusion. This effect should be taken into account when imaging surface structures with charged DBs as well as when studying the diffusion of other atoms and molecules on the Si(100) surface with vacancies in an adsorbate layer.
Screech in transient supersonic jets
Authors: Sheng Juan , Li Xiangru , Wang Yitao , Hao Pengfei , Zhang Xiwen , He Feng
Published: September 2022

The starting processes of under-expanded free jets with nozzle pressure ratios of 2.15, 2.7, and 3.4 are systematically analyzed by large-eddy simulations, and the unified laws of the evolution of the screech frequency and the screech mode in the starting jet are given. Through the development of vortices, the critical time points of the generations of screech tones are investigated. The wavenumber spectra and dispersion relations are employed, showing that the screech feedback loops in the different starting jets are all closed by the neutral waves excited by the interaction between the Kelvin–Helmholtz wavepacket and shock cells of different wavenumbers. The screech frequency prediction during the starting process is put forward for the first time, which is achieved by combining the neutral acoustic wave mode with wavenumber differences between shock cells and the Kelvin–Helmholtz wavepacket. Spectral proper orthogonal decomposition is applied to explain the reason for the change in the interaction mechanism during the starting process.
Recent progress on the interfacial regulation and application of 2D antimonene-based van der Waals heterostructures
Authors: Li Jing , Zhou Wenhan , Xu Lili , Huang Yaxin , Zhang Shengli , Zeng Haibo
Published: September 2022

Two-dimensional (2D) antimonene has triggered a wide range of interest owing to its unique structure and physical properties. Van der Waals heterostructures, which integrate two or more different materials with weak interactions between the layers, offer more degrees of freedom for designing functional materials. Very recently, 2D antimonene-based van der Waals heterostructures have inspired extensive research enthusiasm in various fields. Here, we systematically summarize the band alignment types and regulation strategies of interfacial properties for 2D antimonene-based heterostructures and the state-of-the-art current applications, including electronic and optoelectronic devices, catalysis, energy storage, and the biomedical field. Finally, we discuss the opportunities and challenges and put forward the prospects of 2D antimonene-based heterostructures.
Symmetry-based singlet–triplet excitation in solution nuclear magnetic resonance
Authors: Sabba Mohamed , Wili Nino , Bengs Christian , Whipham James W. , Brown Lynda J. , Levitt Malcolm H.
Published: September 2022

Coupled pairs of spin-1/2 nuclei support one singlet state and three triplet states. In many circumstances, the nuclear singlet order, defined as the difference between the singlet population and the mean of the triplet populations, is a long-lived state that persists for a relatively long time in solution. Various methods have been proposed for generating singlet order, starting from nuclear magnetization. This requires the stimulation of singlet-to-triplet transitions by modulated radiofrequency fields. We show that a recently described pulse sequence, known as PulsePol [Schwartz et al., Sci. Adv., 4, eaat8978 (2018)], is an efficient technique for converting magnetization into long-lived singlet order. We show that the operation of this pulse sequence may be understood by adapting the theory of symmetry-based recoupling sequences in magic-angle-spinning solid-state nuclear magnetic resonance (NMR). The concept of riffling allows PulsePol to be interpreted by using the theory of symmetry-based pulse sequences and explains its robustness. This theory is used to derive a range of new pulse sequences for performing singlet–triplet excitation and conversion in solution NMR. Schemes for further enhancing the robustness of the transformations are demonstrated.
Modeling quantum light interference on a quantum computer
Authors: Vetlugin Anton N. , Soci Cesare , Zheludev Nikolay I.
Published: September 2022

Modeling of photonic devices traditionally involves solving the equations of light–matter interaction and light propagation. Here, we demonstrate an alternative modeling methodology by reproducing the optical device functionality using a quantum computer. As an illustration, we simulate the quantum interference of light on a thin absorbing film. Such interference can lead to either perfect absorption or total transmission of light through the film, the phenomena attracting attention for data processing applications in classical and quantum information networks. We map the behavior of the photon in the interference experiment to the evolution of a quantum state of transmon, a superconducting charge qubit of the IBM quantum computer. Details of the real optical experiment are flawlessly reproduced on the quantum computer. We argue that the superiority of this methodology shall be apparent in modeling complex multi-photon optical phenomena and devices.
Second harmonic AC calorimetry technique within a diamond anvil cell
Authors: Dasenbrock-Gammon Nathan , McBride Raymond , Yoo Gyeongjae , Dissanayake Sachith , Dias Ranga
Published: September 2022

Tuning the energy density of matter at high pressures gives rise to exotic and often unprecedented properties, e.g., structural transitions, insulator–metal transitions, valence fluctuations, topological order, and the emergence of superconductivity. The study of specific heat has long been used to characterize these kinds of transitions, but their application to the diamond anvil cell (DAC) environment has proved challenging. Limited work has been done on the measurement of specific heat within DACs, in part due to the difficult experimental setup. To this end, we have developed a novel method for the measurement of specific heat within a DAC that is independent of the DAC design and is, therefore, readily compatible with any DACs already performing high pressure resistance measurements. As a proof-of-concept, specific heat measurements of the MgB2 superconductor were performed, showing a clear anomaly at the transition temperature (Tc), indicative of bulk superconductivity. This technique allows for specific heat measurements at higher pressures than previously possible.
Importance-sampling FCIQMC: Solving weak sign-problem systems
Authors: Liebermann Niklas , Ghanem Khaldoon , Alavi Ali
Published: September 2022

We investigate the exact full configuration interaction quantum Monte Carlo algorithm (without the initiator approximation) applied to weak sign-problem fermionic systems, namely, systems in which the energy gap to the corresponding sign-free or “stoquastized” state is small. We show that the minimum number of walkers required to exactly overcome the sign problem can be significantly reduced via an importance-sampling similarity transformation even though the similarity-transformed Hamiltonian has the same stoquastic gap as the untransformed one. Furthermore, we show that in the off-half-filling Hubbard model at U/t = 8, the real-space (site) representation has a much weaker sign problem compared to the momentum space representation. By applying importance sampling using a Gutzwiller-like guiding wavefunction, we are able to substantially reduce the minimum number of walkers in the case of 2 × ℓ Hubbard ladders, enabling us to get exact energies for sizable ladders. With these results, we calculate the fundamental charge gap ΔEfund = E(N + 1) + E(N − 1) − 2E(N) for the ladder systems compared to strictly one-dimensional Hubbard chains and show that the ladder systems have a reduced fundamental gap compared to the 1D chains.
Non-reciprocity of vortex-limited critical current in conventional superconducting micro-bridges
Authors: Suri Dhavala , Kamra Akashdeep , Meier Thomas N. G. , Kronseder Matthias , Belzig Wolfgang , Back Christian H. , Strunk Christoph
Published: September 2022

Non-reciprocity in the critical current has been observed in a variety of superconducting systems and has been called the superconducting diode effect. The origin underlying the effect depends on the symmetry breaking mechanisms at play. We investigate superconducting micro-bridges of NbN and also NbN/magnetic insulator (MI) hybrids. We observe a large diode efficiency of ≈30% when an out-of-plane magnetic field as small as 25 mT is applied. In both NbN and NbN/MI hybrid, we find that the diode effect vanishes when the magnetic field is parallel to the sample plane. Our observations are consistent with the critical current being determined by the vortex surface barrier. Unequal barriers on the two edges of the superconductor strip result in the diode effect. Furthermore, the rectification is observed up to 10 K, which makes the device potential for diode based applications over a larger temperature range than before.
Numerical simulation analysis of symmetric impact of two droplets on a liquid film
Authors: Tao Junyu , Chen Desheng , Lin Zhe , Zhu Zuchao
Published: September 2022

Analyzing the impact of a droplet on a liquid film is a typical free-surface problem. However, a few studies have investigated the impact of multiple droplets, and in most cases, the droplet impact direction is assumed to be vertically downward. The effect of the impact angle on the characteristic parameters of the spray remains unknown. In this study, the coupled level set and volume of fluid method is used to analyze the development of the gas–liquid interface when two droplets impact a liquid film, and the grid of the gas–liquid interface is refined using the grid adaptive refinement method. The accuracy of numerical simulation has also been verified. The numerical simulation results showed significant differences in the liquid splash morphology corresponding to the different impact modes. The inward impact of the two droplets promotes splashing, whereas the outward impact inhibits it. The liquid film thickness primarily affects the local splash morphology. The droplet spacing affects the spreading diameter and jet angle. The cylindrical jet formed by the symmetrical inward impact of the droplets is unstable, and the rupture mechanism of the cylindrical jet is elucidated for different impact modes. These results provide reference for the application of droplets impingement.
Mechanism by which T7 bacteriophage protein Gp1.2 inhibits
Escherichia coli
dGTPase
Authors: Klemm Bradley P. , Singh Deepa , Smith Cassandra E. , Hsu Allen L. , Dillard Lucas B. , Krahn Juno M. , London Robert E. , Mueller Geoffrey A. , Borgnia Mario J. , Schaaper Roel M.
Published: September 2022

Levels of the cellular dNTPs, the direct precursors for DNA synthesis, are important for DNA replication fidelity, cell cycle control, and resistance against viruses.
Escherichia coli
encodes a dGTPase (2′-deoxyguanosine-5′-triphosphate [dGTP] triphosphohydrolase [dGTPase];
dgt
gene, Dgt) that establishes the normal dGTP level required for accurate DNA replication but also plays a role in protecting
E. coli
against bacteriophage T7 infection by limiting the dGTP required for viral DNA replication. T7 counteracts Dgt using an inhibitor, the gene
1.2
product (Gp1.2). This interaction is a useful model system for studying the ongoing evolutionary virus/host “arms race.” We determined the structure of Gp1.2 by NMR spectroscopy and solved high-resolution cryo-electron microscopy structures of the Dgt–Gp1.2 complex also including either dGTP substrate or GTP coinhibitor bound in the active site. These structures reveal the mechanism by which Gp1.2 inhibits Dgt and indicate that Gp1.2 preferentially binds the GTP-bound form of Dgt. Biochemical assays reveal that the two inhibitors use different modes of inhibition and bind to Dgt in combination to yield enhanced inhibition. We thus propose an in vivo inhibition model wherein the Dgt–Gp1.2 complex equilibrates with GTP to fully inactivate Dgt, limiting dGTP hydrolysis and preserving the dGTP pool for viral DNA replication.
The
doublesex
gene regulates dimorphic sexual and aggressive behaviors in
Drosophila
Authors: Han Caihong , Peng Qionglin , Sun Mengshi , Jiang Xinyu , Su Xiangbin , Chen Jiangtao , Ma Mingze , Zhu Huan , Ji Xiaoxiao , Pan Yufeng
Published: September 2022

Most animal species display dimorphic sexual behaviors and male-biased aggressiveness. Current models have focused on the male-specific product from the
fruitless
(

fru
M

) gene, which controls male courtship and male-specific aggression patterns in fruit flies, and describe a male-specific mechanism underlying sexually dimorphic behaviors. Here we show that the
doublesex
(
dsx
) gene, which expresses male-specific Dsx
M
and female-specific Dsx
F
transcription factors, functions in the nervous system to control both male and female sexual and aggressive behaviors. We find that Dsx is not only required in central brain neurons for male and female sexual behaviors, but also functions in approximately eight pairs of male-specific neurons to promote male aggressiveness and approximately two pairs of female-specific neurons to inhibit female aggressiveness. Dsx
F
knockdown females fight more frequently, even with males. Our findings reveal crucial roles of
dsx
, which is broadly conserved from worms to humans, in a small number of neurons in both sexes to establish dimorphic sexual and aggressive behaviors.
Memo1 binds reduced copper ions, interacts with copper chaperone Atox1, and protects against copper-mediated redox activity in vitro
Authors: Zhang Xiaolu , Walke Gulshan R. , Horvath Istvan , Kumar Ranjeet , Blockhuys Stéphanie , Holgersson Stellan , Walton Paul H. , Wittung-Stafshede Pernilla
Published: September 2022

The protein mediator of ERBB2-driven cell motility 1 (Memo1) is connected to many signaling pathways that play key roles in cancer. Memo1 was recently postulated to bind copper (Cu) ions and thereby promote the generation of reactive oxygen species (ROS) in cancer cells. Since the concentration of Cu as well as ROS are increased in cancer cells, both can be toxic if not well regulated. Here, we investigated the Cu-binding capacity of Memo1 using an array of biophysical methods at reducing as well as oxidizing conditions in vitro. We find that Memo1 coordinates two reduced Cu (Cu(I)) ions per protein, and, by doing so, the metal ions are shielded from ROS generation. In support of biological relevance, we show that the cytoplasmic Cu chaperone Atox1, which delivers Cu(I) in the secretory pathway, can interact with and exchange Cu(I) with Memo1 in vitro and that the two proteins exhibit spatial proximity in breast cancer cells. Thus, Memo1 appears to act as a Cu(I) chelator (perhaps shuttling the metal ion to Atox1 and the secretory path) that protects cells from Cu-mediated toxicity, such as uncontrolled formation of ROS. This Memo1 functionality may be a safety mechanism to cope with the increased demand of Cu ions in cancer cells.