bluuebunny/crossref_metadata_2025 huggingface dataset:
Merging galaxies in isolated environments
Authors: Calderón-Castillo Paula , Smith Rory
Published: October 2024

Context. It is now well known that certain massive galaxies undergo enormous enhancements in their star formation rate (SFR) when they undergo major mergers. These enhancements can be as high as 100 times the SFR of unperturbed galaxies of the same stellar mass. Previous works have found that the size of this boost in star formation (SF) is related to the morphology of and the proximity to the companion. The same trend has also been observed for the fraction of active galactic nuclei (AGN), where galaxies that are closer together tend to have higher AGN fractions.

Aims. We aim to analyse the SF enhancement and AGN fraction evolution during the merger process by using a more timeline-like merger sequence. Additionally, we aim to determine the relation between the SF enhancement in mergers and the morphology of the galaxies involved.

Methods. Taking advantage of the stellar masses (M*) and SFRs of the ∼600 nearby isolated mergers obtained in our previous study, we calculated the distance of each of our galaxies from the star-forming main sequence (MS; specific SFR (sSFR)/sSFRMS), which werefer to as the SF mode. We then analysed how the SF mode varies during the merger process as a function of morphology and M*. Additionally, we analysed the AGN content of our mergers, using multiple diagnostics based on emission line ratios and WISE colours.

Results. We observed that, overall, merging galaxies show an SF mode that is governed by their morphology. Spirals typically show high SF mode values, while highly disturbed (HD) galaxies are generally even more enhanced (median values of +0.8 dex and +1.08 dex above the MS, respectively). In contrast, elliptical and lenticular galaxies show the lowest SF modes, as expected. However, even they show SF enhancement compared to their unperturbed counterparts. For example, their median SF mode is just within the 1-sigma scatter of the MS, and this can occur even before the galaxies have coalesced. We observed a trend for the SF mode to gradually increase with increasing merger stage. We did not find a clear dependency of the observed AGN fraction on the merger stage for the majority of our classification methods.

Conclusions. We find mergers can significantly enhance SF in galaxies of all morphologies. For early-type galaxies, this could suggest that some gas was present prior to the merger, which may be triggered to form stars by the tidal interaction. As the SF enhancement continues throughout the merger process, this suggests that the enhancement may be a long-lived event, contrary to the short starbursts seen in some models.
Secrets in the shadow: High precision stellar abundances of fast-rotating A-type exoplanet host stars through transit spectroscopy
Authors: Lam M. B. , Hoeijmakers H. J. , Prinoth B. , Thorsbro B.
Published: October 2024

Context. The spectra of fast-rotating A-type stars have strongly broadened absorption lines. This effect causes blending of the absorption lines, hindering the measurement of the abundances of the elements that are in the stellar photosphere.

Aims. As the exoplanet transits across its host star, it obscures the stellar spectrum that is emitted from directly behind the planet. We aim to extract this obscured spectrum because it is less affected by rotational broadening, resolving the blending of weak lines of elements that would otherwise remain inaccessible. This allows us to more precisely measure the metal abundances in ultra-hot Jupiter systems, many of which have fast-rotating host stars.

Methods. We developed a novel method that isolates the stellar spectra behind the planet during a spectral time series, and reconstructs the disc-integrated non-broadened spectrum of the host star. We have systematically tested this method with model-generated spectra of the transit of WASP-189 b across its fast-rotating A-type host star, assessing the effects of limb-darkening, the choice of absorption lines, and the signal-to-noise regime; and demonstrating the sensitivity to photospheric parameters (Teff and log g) and elemental abundances. We applied the method to observations by the HARPS high-resolution spectrograph.

Results. For WASP-189, we obtain the metallicity and photospheric abundances for several species previously not reported in literature, Mg, Ca, and Ti, with a significantly improved accuracy compared to the ordinary broadened stellar spectrum. This method can be generally applied to other transiting systems in which abundance determinations via spectral synthesis are imprecise due to severe line blending. It is important to accurately determine the photospheric properties of exoplanet host stars, as it can provide further insight into the formation and evolution of the planets.
The obliquity and atmosphere of the hot Jupiter WASP-122b (KELT-14b) with ESPRESSO: An aligned orbit and no sign of atomic or molecular absorption
Authors: Stangret M. , Palle E. , Esparza-Borges E. , Orell Miquel J. , Casasayas-Barris N. , Zapatero Osorio M. R. , Cristo E. , Allart R. , Alibert Y. , Borsa F. , Demangeon O. D. S. , Di Marcantonio P. , Ehrenreich D. , Figueira P. , González Hernández J. I. , Herrero-Cisneros E. , Martins C. J. A. P. , Santos N. C. , Seidel J. V. , Azevedo Silva T. , Sozzetti A. , Steiner M. , Suárez Mascareño A. , Udry S.
Published: October 2024

Thanks to their short orbital periods and hot extended atmospheres, hot Jupiters are ideal candidates for atmosphere studies with high- resolution spectroscopy. New stable spectrographs help improve our understanding of the evolution and composition of those types of planets. By analyzing two nights of observations using the ESPRESSO high-resolution spectrograph, we studied the architecture and atmosphere of hot Jupiter WASP-122b (KELT-14b). By analyzing the Rossiter-McLaughlin (RM) effect, we measured the spin-orbit angle of the system to be λ = 0.09−0.90+0.88 deg. This result is in line with literature obliquity measurements of planetary systems around stars with effective temperatures cooler than 6500 K. Using the transmission spectroscopy, we studied the atmosphere of the planet. Applying both the single-line analysis and the cross-correlation method, we looked for Ca I, Cr I, FeH, Fe I, Fe II, H2O, Li I, Mg I, Na I, Ti I, TiO, V I, VO, and Y I. Our results show no evidence of any of these species in WASP-122b’s atmosphere. The lack of significant detections can be explained by either the RM effect covering the regions where the atmospheric signal is expected and masking it, along with the low signal-to-noise ratio (S/N) of the observations or the absence of the relevant species in its atmosphere.
The properties of magnetised cold filaments in a cool-core galaxy cluster
Authors: Fournier M. , Grete P. , Brüggen M. , Glines F. W. , O’Shea B. W.
Published: October 2024

Context. Filaments of cold gas (T ≤ 104 K) are found in the inner regions of many cool-core clusters. These structures are thought to play a major role in the regulation of feedback from active galactic nuclei (AGNs).

Aims. We study the morphology of the filaments, their formation, and their impact on the propagation of the outflowing AGN jets.

Methods. We present a set of GPU-accelerated 3D magnetohydrodynamic simulations of an idealised Perseus-like cluster using the performance portable code ATHENAPK. We include radiative cooling and a self-regulated AGN feedback model that redistributes accreted material through kinetic, thermal, and magnetic feedback.

Results We confirm that magnetic fields play an important role in both the formation and evolution of the cold material. These suppress the formation of massive cold discs and favour magnetically supported filaments over clumpy structures. Achieving resolutions of 25 − 50 pc, we find that filaments are not monolithic as they contain numerous and complex magnetically supported sub-structures. We find that the mass distribution of these clumps follows a power law of slope of ∼ − 0.6 for all investigated filaments. Studying the evolution of individual filaments, we find that their formation pathways can be diverse. We find examples of filaments forming through a combination of gas uplifting and condensation, as well as systems of purely infalling clumps condensing out of the intracluster medium. The density contrast between the cold gas and the outflowing hot material leads to recurring deflections of the jets, favouring inflation of bubbles.

Conslusions. Filaments in cool-core clusters are clumpy and contain numerous sub-structures, resulting from a complex interplay between magnetic fields, thermal instability, and jet-cloud interaction. Frequent deflections of the AGN outflows suppress jet collimation and favour the formation of large X-ray bubbles, and smaller off-axis cavities.
Gaia/GSP-spec spectroscopic properties of γ Doradus pulsators
Authors: de Laverny P. , Recio-Blanco A. , Aerts C. , Palicio P. A.
Published: October 2024

Context. The third Data Release of the ESA Gaia mission has provided a large sample of new gravity-mode pulsators, among which more than 11 600 are γ Dor stars.

Aims. The goal of the present work is to present the spectroscopic parameters of these γ Dor pulsators estimated by the GSP-Spec module that analysed millions of Gaia spectra. Such a parametrisation could help confirm their γ Dor nature and provide their chemo-physical properties.

Methods. The Galactic positions, kinematics, and orbital properties of these new Gaia pulsators were examined in order to define a sub-sample belonging to the Milky Way thin disc, in which these young stars should preferentially be found. The stellar luminosities, radii, and astrometric surface gravities were estimated without adopting any priors from uncertain stellar evolution models. These parameters, combined with the GSP-Spec effective temperatures, spectroscopic gravities, and metallicities were then validated by comparison with recent literature studies.

Results. Most stars are found to belong to the Galactic thin disc, as expected. It is also found that the derived luminosities, radii, and astrometric surface gravities are high quality and have values typical of genuine γ Dor pulsators. Moreover, we show that Teff and [M/H] of pulsators with high enough S/N spectra or slow to moderate rotation rates are robust. This allowed to define a sub-sample of genuine slow-rotating Gaiaγ Dor pulsators. Their Teff were found to be between ∼6500 and ∼7800 K, log(g) is around 4.2, and the luminosities and stellar radii peak at ∼5 L⊙ and ∼1.7 R⊙, The median metallicity is close to the Solar value, although γ Dor with higher and lower metallicities by about ±0.5 dex were also identified. The [α/Fe] content is fully consistent with the chemical properties of the Galactic disc.

Conclusions.Gaia/DR3 spectroscopic properties of γ Dor stars therefore confirm the nature of these pulsators and allow to chemo-physically parametrise a new large sample of such stars. Moreover, future Gaia data releases should drastically increase the number of γ Dor stars with parameters spectroscopically derived with good precision.
Editorial: Green Taxonomy for Sustainable Development
Authors: Kuzmin Evgeny , Mirzaev Bakhadir , Alimov Uchkun
Published: October 2024

The article examines the concept of green taxonomy as a key tool for sustainable development aimed at overcoming modern challenges. Green taxonomy is viewed as a classification system that allows identifying and assessing activities in terms of their contribution to achieving sustainable development goals. The focus is on systematizing activities in the following sectors: power, transport, agriculture, construction and waste management. The article discusses the prospects and potential threats of green taxonomy. Green taxonomy has significant potential to accelerate the transition to a sustainable economic model, support international climate commitments, and stimulate innovation. The study also highlights the need to improve the mechanisms for implementing green taxonomy to ensure its effectiveness and adaptation to changing conditions and needs of society.
Japan’s Experience in the Development of Industry and Green Technologies
Authors: Mirzayev Muzaffar , Toderich Kristina N. , Botirova Halima
Published: October 2024

This article analyzes various aspects of the introduction and use of innovative technologies in Japanese industry, with an emphasis on green transformation and sustainable development. The authors consider the influence of Japan’s strong innovation base and technological potential on the development of green technologies, covering various sectors of the economy. The main focus is on government policies aimed at accelerating the introduction of environmentally friendly technologies, as well as the role of private capital in this process. We discuss the key factors contributing to the transformation of Japanese industry, including demographic changes, declining productivity and international competitiveness. The article emphasizes the importance of industrial agglomeration and cooperation in enhancing competitiveness. The study is of interest to researchers and practitioners working on sustainable development and industrial policy.
Customized Genioplasty and Advantages of 3D Virtual Planning: An Updated Literature Review
Authors: Illarramendi Imanol Zubiate , Cariati Paolo , Martínez-Sahuquillo Ángel , Iglesias Fernando Monsalve
Published: October 2024

Genioplasty is a surgical technique that modifies the projection of the chin in three dimensions to achieve symmetry and facial harmonization. Virtual 3D planning is increasingly used, supplanting the conventional surgical technique due to the precise and predictable results obtained.

The definition of the objective of the study was first carried out using the PICO (Patient, Intervention, Comparison, Outcome) question method. Posteriorly, an updated literature review was carried out in the “PubMed” database using the keywords “Genioplasty and Virtual 3D Planning,” obtaining 11 articles for the study with the objective of defining the advantages and disadvantages of performing a virtually planned genioplasty, comparing it with the conventional technique.

In the results, it is observed that virtually planned genioplasty presents greater precision, a reduction in surgical time, and a lower rate of complications than the conventional technique. Virtual planning using computer-aided design/computer-aided manufacturing technology presents good reproducibility in the patient with <2 mm variations between what was planned and what was obtained postoperatively, with statistically significant results (p < 0.001).

In conclusion, virtually planned genioplasty with customized cutting guides and osteosynthesis plates achieves very precise surgery results with good reproducibility, reducing surgical time, intraoperative complications, and the difficulty of the surgical technique.
Celebrating 25 Years of Optical Biometry: A Milestone in Ophthalmology
Authors: Scholtz Sibylle Katharina , Langenbucher Achim , Stachs Oliver
Published: October 2024

Optical biometry has fundamentally transformed cataract surgery, and 2024 marked 25 years since the introduction of the first optical biometer. In the early 1980 s, Fercher and colleagues pioneered the optical noncontact eye length measurement, leading to the first interferometric A-scan of the eye. This innovation, patented and later developed by Zeiss, culminated in the release of the IOLMaster in 1999, enabling more accurate and reproducible eye diagnostics. Over the years, optical biometry has evolved into advanced swept-source optical coherence tomography devices, accompanied by numerous formulas for calculating intraocular lens power. Today, this technology is crucial not only for cataract surgeries, especially in eyes previously treated with refractive surgery, but also in advancing our understanding of diseases across fields like cardiology and oncology.
A Metal-Free Strategy for the Synthesis of Symmetrical 2,3,5,6-Tetrasubstituted Pyridines Using Triethyl Orthoformate as a Carbon Source
Authors: Cheng Luoteng , Shang Suqin , Yuan Jian Yong , Li Yanwu , Zhang Xiuyu , Li Suzhen , Ma Wanqian , Guo Mengyi , Song Yibo , Guo Qian , Song Yifan
Published: October 2024

A simple and efficient method for the synthesis of symmetric 2,3,5,6-tetrasubstituted pyridines from enaminones and triethyl orthoformate, catalyzed by pyridinium p-toluenesulfonate, has been established in which triethyl orthoformate was applied as a carbon source. The procedure was smoothly executed, culminating in the synthesis of symmetrical 2,3,5,6-tetrasubstituted pyridines with moderate to exceptional yields across a diverse array of substrates.
Evaluation of a Primary Care-Integrated Mobile Health Intervention to Monitor between-Visit Asthma Symptoms
Authors: Sulca Flores Jorge A. , Dalal Anuj K. , Sousa Jessica , Foer Dinah , Rodriguez Jorge A. , Plombon Savanna , Bates David W. , Arcia Adriana , Rudin Robert S.
Published: October 2024

Objectives This study aimed to evaluate implementation of a digital remote symptom monitoring intervention that delivered weekly symptom questionnaires and included the option to receive nurse callbacks via a mobile app for asthma patients in primary care.

Methods Research questions were structured by the NASSS (Nonadoption, Abandonment, Scale-up Spread, and Sustainability) framework. Quantitative and qualitative methods assessed scalability of the electronic health record (EHR)-integrated app intervention implemented in a 12-month randomized controlled trial. Data sources included patient asthma control questionnaires; app usage logs; EHRs; and interviews and discussions with patients, primary care providers (PCPs), and nurses.

Results We included app usage data from 190 patients and interview data from 21 patients and several clinician participants. Among 190 patients, average questionnaire completion rate was 72.3% and retention was 78.9% (i.e., 150 patients continued to use the app at the end of the trial period). App use was lower among Hispanic and younger patients and those with fewer years of education. Of 1,185 nurse callback requests offered to patients, 33 (2.8%) were requested. Of 84 PCP participants, 14 (16.7%) accessed the patient-reported data in the EHR. Analyses showed that the intervention was appropriate for all levels of asthma control; had no major technical barriers; was desirable and useful for patient treatment; involved achievable tasks for patients; required modest role changes for clinicians; and was a minimal burden on the organization.

Conclusion A clinically integrated symptom monitoring intervention has strong potential for sustained adoption. Inequitable adoption remains a concern. PCP use of patient-reported data during visits could improve intervention adoption but may not be required for patient benefits.
9.9.6 Furans (Update 2024)
Authors: Kwiecień H. U.
Published: October 2024

This review is an update to the earlier Science of Synthesis contributions presenting methods for the synthesis of furans. It focuses on the literature published between 2011 and 2022. In the last decade, a number of new methods for the synthesis of furans from acyclic functionalized molecules have been developed. Many of the methods are based on (mixed) transition-metal catalysis, which induces several combinations of isomerizations, rearrangements, and cyclizations, leading to reactions that are termed cycloisomerizations. Multicomponent reactions for the synthesis of furans are also included.
Robust optimization of community energy sharing considering source-load uncertainty and demand response
Authors: Yang Di , Lv Yuntong , Ji Ming , Wang Zhitao , Xie Zhenlin , Hu Yinlong
Published: October 2024

Community energy consumption is a crucial aspect of the overall societal energy consumption landscape. The allocation rate of distributed photovoltaic (PV) systems within communities is steadily increasing. However, managing and optimizing the consumption of PV resources while mitigating the impact of their inherent randomness and volatility, along with minimizing electricity costs, presents a significant challenge. This paper proposes a mechanism for community energy sharing that utilizes rooftop PV systems, energy storage systems, and bi-directional electric vehicles. To achieve the goal of finding the minimum cost of electricity in the worst scheduling scenarios, a two-stage robust optimization model is established. This model considers the two-sided uncertainty of source and load as well as flexible load demand response. The simulation outcomes prove the proposed method's efficacy in substantially mitigating residential electricity costs and enhancing PV utilization. Notably, during peak summer demand, a substantial 24.78% reduction in electricity costs was achieved, while PV utilization witnessed a significant 16.52% increase.
Remote RF generation from ultrafast laser plasmas
Authors: Reyes Danielle , Kerrigan Haley , Bodnar Nathan , Bernath Robert , Barbieri Nicholas , Richardson Martin
Published: October 2024

Ultrashort pulse (USP) lasers provide a novel approach to microwave production for remote applications. In this scheme, the plasma produced in the interaction of a USP with a material surface at a distance serves as a localized source of radio frequency (RF) radiation. Ultrashort pulses allow for the long-range projection of high-intensity light (∼1013 W/cm2), through the phenomenon of laser filamentation, thereby enabling the efficient generation of transient plasmas on remote material surfaces. In this paper, the mechanism of RF production in the laser–matter interaction is discussed and experimental characterization of the RF emission in a variety of target geometries is presented. Both transient dipole radiation and resonance absorption are discussed as theoretical mechanisms of RF generation. Furthermore, spectral composition of the RF emission, angular distribution of the emission, and dependence of the RF on laser focusing conditions are all characterized for a number of target materials in the single to tens of GHz range, using microwave horn antennas in conjunction with heterodyning electronics.
Achieving photomultiplication in organic-MOF complex via interface and band engineering
Authors: Joshi Medha , Sridhar Sampati Rao , Verma Upendra Kumar , Kumar Brijesh
Published: October 2024

This work studies a hybrid broadband photodetector with and without metal–organic framework nanosheets with an inverted structure. It is observed that an inverted structure provides photomultiplication in the devices with both positive and negative biases. This phenomenon is believed to be due to a non-uniform TiO2/active layer interface where the porosity of TiO2 facilitates structural traps, in turn achieving photomultiplication in P3HT: PCBM (1:1) devices. Meanwhile, in photodetectors with an active layer of P3HT:ZnTCPP:PCBM (1:0.5:1), photomultiplication is attributed to interface traps and band alignment due to ZnTCPP nanosheets. The presence of ZnTCPP reduces the dip in EQE at 370–460 and 530–610 nm range, thus improving broadband detection (300–700 nm). Adding ZnTCPP to the devices results in improved rise and fall times. The on–off response is also relatively stable for the devices with ZnTCPP and has high detectivity (1011 Jones). Thus, this study sheds light on the role of a thin interface layer of TiO2 in photomultiplication and improving performance parameters with ZnTCPP nanosheets.
Full-wave simulations on helicon and parasitic excitation of slow waves near the edge plasma
Authors: Kim E.-H. , Ono M. , Shiraiwa S. , Bertelli N. , Poulos M. , Van Compernolle B. , Bortolon A. , Pinsker R. I.
Published: October 2024

Helicon waves are thought to be promising in various tokamaks, such as DIII-D, because they can penetrate reactor-grade high-density cores and drive the off-axis current with higher efficiency. In the frequency regime ∼ 476 MHz, both slow electrostatic and fast electromagnetic helicon waves can coexist in DIII-D. If the antenna parasitically excites the slow mode, these waves can propagate along the magnetic field line into the scrape-off layer (SOL). Although the importance of the misalignment of the Faraday screen and the electron density in the SOL on the excitation and propagation of slow modes is well known, the conditions for minimizing slow mode excitation have yet to be optimized. Using the Petra-M simulation code in the 2D domain, we analyze the effects of the misalignment of the antenna in the poloidal direction, the misalignment of the Faraday screen in the toroidal direction, and the density in front of the antenna on slow mode generation. Our results suggest that the misalignment of the Faraday screen is a critical factor in reducing the slow mode and that the misalignment angle should be below ∼ 5° to minimize the slow wave excitation. When the electron density is higher than 3.5×1018 m−3 in the SOL, the generation of the slow mode from the antenna is minimized and unaffected by the misalignment of the Faraday screen.
Accelerating the convergence of coupled cluster calculations of the homogeneous electron gas using Bayesian ridge regression
Authors: Butler Julie , Hjorth-Jensen Morten , Lietz Justin G.
Published: October 2024

The homogeneous electron gas is a system that has many applications in chemistry and physics. However, its infinite nature makes studies at the many-body level complicated due to long computational run times. Because it is size extensive, coupled cluster theory is capable of studying the homogeneous electron gas, but it still poses a large computational challenge as the time needed for precise calculations increases in a polynomial manner with the number of particles and single-particle states. Consequently, achieving convergence in energy calculations becomes challenging, if not prohibited, due to long computational run times and high computational resource requirements. This paper develops the sequential regression extrapolation (SRE) to predict the coupled cluster energies of the homogeneous electron gas in the complete basis limit using Bayesian ridge regression and many-body perturbation theory correlation energies to the second order to make predictions from calculations at truncated basis sizes. Using the SRE method, we were able to predict the coupled cluster double energies for the electron gas across a variety of values of N and rs, for a total of 70 predictions, with an average error of 5.20 × 10−4 hartree while saving 88.9 h of computational time. The SRE method can accurately extrapolate electron gas energies to the complete basis limit, saving both computational time and resources. Additionally, the SRE is a general method that can be applied to a variety of systems, many-body methods, and extrapolations.
Experimental study of thermoconcentration convection in air–water and air–undecane mixtures
Authors: Somov Sergey A. , Ivanov Aleksey S.
Published: October 2024

A quantitative experimental comparison was conducted between thermal convection in dry air and thermoconcentration convection in two gas mixtures: air–water vapor and air–undecane vapor, within the temperature range of 0–80 °C at normal atmospheric pressure. Convection in these mixtures is driven by temperature and concentration gradients of water (or undecane) vapor in the air. The stationary thermoconcentration convection is accompanied by continuous phase transitions of the fluids. The quantitative results of the experiments are represented in terms of the Nusselt number Nu and the effective Rayleigh number RaE, which is the sum of the thermal RaT and concentration RaC Rayleigh numbers. Quantitative laboratory measurements were performed using the thermocouple method and were supplemented with qualitative data from visual monitoring of transparent fluid flows using holographic interferometry. The cubic and quadratic temperature dependencies of RaCRaT−1 were determined experimentally for moist air and for the air–undecane vapor mixture, respectively. The significant role of moisture phase transitions in air convection is established. Neglecting these effects at 25 °C and using the ordinary RaT instead of actual RaE would result in an error exceeding 30%. At 38 °C, this error would increase to nearly 100%. At around 80 °C, thermoconcentration convection becomes almost entirely concentration-driven, as the high molecular disordered thermal motion is suppressed by the ordered convective motion generated by evaporation and condensation of water on the opposite heat exchangers of the convective cell.
A linear shaped charge cutting model for brittle flat plates
Authors: Zhao Zheng , Xi Haobo , Tan Rui , Li Dongyu
Published: October 2024

The dynamic response and damage fracture of brittle materials under explosive cutting have always been important research issues in the fields of military, aerospace, and other engineering fields. In this paper, a linear shaped charge cutting model for explosive cutting of brittle materials is proposed. This model suggests that explosive cutting is caused by the combined effects of jet penetration, spallation, and impact fracture. Theoretical calculation models for jet penetration, spallation, and impact fracture were constructed, and the concept of impact strength was introduced to establish dynamic mechanical performance parameters for brittle materials. A calculation program for explosive cutting of brittle materials was developed using the Python language, which can calculate the jet penetration depth, spallation thickness, and impact fracture thickness by inputting parameters such as the size and mechanical properties of the linear shaped charge and target plate, and determine whether the target plate can be successfully cut. Subsequently, a series of explosion cutting experiments and numerical simulations for brittle target plates were conducted to verify the accuracy of the calculation program. The results indicate a high degree of consistency between simulation, experimentation, and program calculation results. This work can provide guidance and promotion for the design and application of explosive energy harvesting cutters.
Suppressed nonradiative electron–hole recombination in bismuth halide perovskite Cs3Bi2Cl9: Time domain ab initio analysis
Authors: Zhou Junjie , Guan Yinglin , Wen Minru , Huang Le , Dong Huafeng , Wu Fugen , Meng Xiangyue
Published: October 2024

Time-domain density functional theory, coupled with non-adiabatic molecular dynamics simulations, was employed to explore the defect characteristics and the associated nonradiative recombination processes in the bismuth halide perovskite Cs3Bi2Cl9. Our findings indicate that Cs3Bi2Cl9 inherently exhibits p-type semiconductor behavior, with vacancies at the Cs and Bi sites acting as predominant shallow acceptor defects. Although Cl vacancy and interstitial Cl defects introduce trap states within the bandgap of Cs3Bi2Cl9, the by-defect electron–hole (e-h) recombination is substantially impeded, which is attributed to the remarkable local structural deformations associated with the BiCl63− octahedral compression around the defects, which further results in decoupling between the defect state and the band edge state. As a result, the enhanced delocalization of defect states leads to a notably small wave function overlap between defect states and band edge states, as well as weak nonadiabatic couplings dominated by low-frequency phonons. Our study offers crucial insights into the mechanism of defect-mediated e-h recombination in bismuth-based perovskites and provides guidelines for designing efficient optoelectronic devices based on these materials.
Time evolutions of information entropies in a one-dimensional Vlasov–Poisson system
Authors: Maekaku K. , Sugama H. , Watanabe T.-H.
Published: October 2024

A one-dimensional Vlasov–Poisson system is considered to elucidate how the information entropies of the probability distribution functions of the electron position and velocity variables evolve in the Landau damping process. Considering the initial condition given by the Maxwellian velocity distribution with the spatial density perturbation in the form of the cosine function of the position, we derive linear and quasilinear analytical solutions that accurately describe both early and late time behaviors of the distribution function and the electric field. The validity of these solutions is confirmed by comparison with numerical simulations based on contour dynamics. Using the quasilinear analytical solution, the time evolutions of the velocity distribution function and its kurtosis indicating deviation from the Gaussian distribution are evaluated with the accuracy of the squared perturbation amplitude. We also determine the time evolutions of the information entropies of the electron position and velocity variables and their mutual information. We further consider Coulomb collisions that relax the state in the late-time limit in the collisionless process to the thermal equilibrium state. In this collisional relaxation process, the mutual information of the position and velocity variables decreases to zero, while the total information entropy of the phase-space distribution function increases by the decrease in the mutual information and demonstrates the validity of Boltzmann's H-theorem.
Effects of nonlinearity on the crest shape of extreme irregular sea waves: Nonlinear harmonic separation and analysis
Authors: Spiliotopoulos George , Katsardi Vanessa
Published: October 2024

This work highlights the effects of nonlinearity on the crest shape of extreme directional water wave events in infinite and finite water depths. HOS-ocean, a High-Order Spectral code developed for solving the deterministic propagation of nonlinear wavefields in open ocean [Ducrozet et al., “HOS-ocean: Open-source solver for nonlinear waves in open ocean based on High-Order Spectral method,” Comput. Phys. Commun. 203, 245–254 (2016)], is used for comparisons with linear simulations. Nonlinear wave harmonics were extracted combining and extending previous methods [Fitzgerald et al., “Phase manipulation and the harmonic components of ringing forces on a surface-piercing column,” Proc. R. Soc. A 470, 20130847 (2014) and Hann et al., “A new set of focused wave linear combinations to extract non-linear wave harmonics,” in Proceedings of 29th International Workshop on Water Waves and Floating Bodies, 2014], showing the contribution of various orders of nonlinearity. The work shows that “walls of water,” [Adcock et al., “Nonlinear dynamics of wave-groups in random seas: Unexpected walls of water in the open ocean,” Proc. R. Soc. A 471, 20150660 (2015) and Adcock et al., “On the shape of large wave-groups on deep water—The influence of bandwidth and spreading,” Phys. Fluids 28, 106601 (2016)], a significant increase in the crest width, are also formulated in finite water depths. Mainly responsible for this is the first order harmonic, with significant energy transfers away from components propagating at an angle, which are more pronounced in finite water depths. As nonlinearity increases, higher order harmonics (>second) become, as expected, more significant. In deep water, rapid energy transfers lead to a broadening of the spectrum which is reflected in the increase in the first order amplitude sum and hence increased crest elevations at the point of the large event. However, in finite water depths, energy transfers are gradually leading to a narrowing of the spectrum around the spectral peak and to a general broadening of the spectrum at the higher harmonics; reflected in the significant decrease in the first order amplitude sum and hence a decrease in crest elevations at the point of the large event, also aided by the larger increase in the out-of-phase difference terms (zeroth harmonic).
Patterned 3D-graphene for self-powered broadband photodetector
Authors: Wang Bingkun , Zhang Jinqiu , Lian Shanshui , Wu Huijuan , Liu Zhiduo , Wang Gang
Published: October 2024

The remarkable ultra-wideband energy capabilities of zero-bandgap two-dimensional (2D) graphene have made it an outstanding material for photon absorption and charge carrier generation across a broad spectrum. However, atomically thick 2D-graphene only exhibits a light absorption efficiency of 2.3%, posing a challenge for graphene-based photodetectors to harness photon energy effectively. This study utilized plasma-enhanced chemical vapor deposition technology and a mask to create in situ patterned 3D-graphene/Si-based Schottky heterojunctions. The porous structure and natural nano-resonant cavities of the 3D-graphene enhanced the probability of light absorption, while the curved and sharp edges and corners of the patterned 3D-graphene concentrated the local electromagnetic field and induced localized surface plasmon resonance. Both theoretical and experimental analyses confirmed the improved light absorption mechanisms and charge transfer of photogenerated carriers under the built-in electric field. The photodetector based on the patterned 3D-graphene/Si Schottky structure exhibits excellent broadband response characteristics spanning from 380 to 1550 nm, with responsivity and specific detectivity of 68.47 A/W and 1.43 × 1012 Jones at a wavelength of 1550 nm. Furthermore, the photodetector demonstrated ultrafast microsecond-level response times (116/120 μs rise/fall times) along with exceptional stability and reliability. The potential applications of as-fabricated photodetector include logic devices such as “AND” and “OR” gates and information encryption. This research holds valuable scientific significance for the design of future optoelectronic devices and provides crucial insights and technical support for developing high-performance Si-based graphene detectors.
Charge trapping gate stack enabled non-recessed normally off AlGaN/GaN HEMT with high threshold voltage stability
Authors: Wen Kangyao , He Jiaqi , Jiang Yang , Du Fangzhou , Deng Chenkai , Wang Peiran , Tang Chuying , Li Wenmao , Hu Qiaoyu , Sun Yuhan , Wang Qing , Jiang Yulong , Yu Hongyu
Published: October 2024

This paper reports a non-recessed normally off AlGaN/GaN high-electron-mobility transistor (HEMT) with a charge trapping gate dielectric stack. The charge trapping gate dielectric stack featuring a low density of fixed positive charges consists of an O3-based Al2O3 tunneling layer and an O3-based HfO2 blocking layer, both deposited via atomic layer deposition. For HEMT with a 15 nm AlGaN barrier layer, a threshold voltage of 2.57 V and an on-resistance of 8.50 Ω × mm are achieved. For positive bias temperature instability (PBTI) testing, the electric field provided by the 15 nm AlGaN layer serves as a barrier to channel carriers, significantly enhancing the PBTI test stability. The optimized gate dielectric stack enables the fabrication of the non-recessed normally off metal–insulator–semiconductor-HEMT with enhanced threshold voltage (Vth) stability.
Comparison of machine learning algorithms on a low heat rejection diesel engine running on ternary blends
Authors: Pandey Krishna Kumar , Khayum Naseem , Shaik Jakeer Hussain
Published: October 2024

Depletion of fossil fuels and increasing the energy demand are the critical concerns for the sustainable growth of every country. These challenges highlight the need for a cleaner fuel globally. In particular, substituting the petroleum fuels with biofuels could significantly support sustainability. Hence, this study explores the impact of acetylene induction in a low heat rejection (LHR) diesel engine with ternary blend (TB) as a pilot fuel. TB includes 10%methanol + 20%WCOB + 70%diesel. During the dual fuel operation, the acetylene induction was varied (12, 18, and 24 lpm) with different pilot fuel combinations in a LHR engine. From the experimental results, it was revealed that brake thermal efficiency (BTE) is improved by 10.3% for TB with acetylene at 24 lpm and increased the exhaust gas temperature (EGT) by 10.3% at full load conditions. This study further evaluates the implementation of machine learning algorithms, namely, Random Forest regression (RFR) and Polynomial regression (PR) in predicting the performance parameters [BTE, brake-specific fuel consumption (BSFC), and EGT]. The results indicate that RFR outperforms PR in accurately predicting engine performance characteristics with a coefficient of determination R2 = 0.97, R2 = 0.98 for BTE, whereas for BSFC the R2 = 0.96, R2 = 0.95, and for EGT, the R2 = 0.95, R2 = 0.97 for the test fuels diesel and TBA3, respectively. These findings suggest that the combination of LHR technology, TB fuel, and acetylene can enhance engine efficiency and performance characteristics, and machine learning models can effectively predict these outcomes.
Theoretical insights into laser-assisted field evaporation of ionic compounds
Authors: Xia Yu , Tang Liangpo , Lu Xiaoqin , Zhu Shanna
Published: October 2024

This study addresses the kinetic process of field evaporation of MgO assisted by ultrafast laser pulses combining density functional theory and molecular dynamics. A quantitative model is presented to describe the competitive evaporation of Mg and O ions under various conditions by comparing the activation barriers. The coordination number has a significant impact on the evaporation kinetics. The evaporation ratio of Mg to O rises with increasing DC field strength and laser intensity. Moreover, the energetics of evaporation is in correlation with photo-induced field ionization, revealing distinct mechanisms of evaporation for Mg and O. While Mg undergoes further ionization and field evaporation simultaneously, the evaporation of O is coupled with the relaxation of excited carriers. The final charge state of evaporated O is determined by the DC field strength rather than the laser intensity. Our findings provide insights into laser–matter interactions in ionic compounds and contribute to the development of atom probe techniques.
High-Q all-dielectric metasurface perfect absorber powered by quasi-bound states in the continuum
Authors: Huang Zhisen , Wang Jin , Jia Wei , Zhang Shanwen , Zhou Changhe
Published: October 2024

All-dielectric perfect absorbers powered by quasi-bound states in the continuum (-BIC) are of great importance for developing high-performance optoelectronic devices because they provide high Q-factor absorption. However, these structures usually require the addition of metal back reflectors or degenerate critical coupling to achieve high absorption, which often introduces problems such as Joule heat output and sensitivity to geometrical parameters. In this work, we present an all-dielectric high Q-factor metasurface perfect absorber (MPA) with a cell structure consisting of split Si elliptical disks. By adjusting the tilt angle of the gap, the metasurface can excite a single quasi-BIC resonance in a highly reflective background, corresponding to the electric quadrupole (EQ) mode. Due to the asymmetric coupling of the EQ mode, the proposed metasurface easily breaks the 50% absorption limit. At the wavelength of 894.645 nm, the metasurface achieves a perfect absorption of more than 99% and has a Q-factor of up to 1955. In addition, the structure shows excellent tolerance to geometrical parameters while ensuring high absorption performance. By adjusting the polarization angle, we have also achieved an arbitrary tuning of the absorption efficiency without frequency shift. This work provides a viable scheme for the design of tunable, large-tolerance, and high-Q all-dielectric MPAs, which have a broad potential application in the fields of optical filtering, optical switching, and polarization detection.
Circuits for the spectroscopic readout of bits from molecular quantum-dot cellular automata
Authors: Cong Peizhong , Rocque Alexander , Blair Enrique P.
Published: October 2024

Molecular quantum-dot cellular automata (QCA) may provide high speed, low-power, classical information processing in the post-CMOS era. The readout of molecular QCA bits is challenging because the molecules may be much smaller than transistors and even single-electron transistors. This paper builds on a recent proposal for the spectroscopic readout of bits from asymmetric QCA molecules. Here, we propose circuits for fanning out a bit onto a large QCA circuit to increase the spectroscopic signal-to-noise ratio. As the number of molecules in a fanout circuit grows, the internal bias of each asymmetric cell accumulates, and the circuit may become stuck, tolerating only a very small internal bias. We also propose the use of an applied electric field to compensate for a candidate molecule’s internal bias, thereby restoring switchability, even when the internal bias is significant.
Molecular forecasting of domoic acid during a pervasive toxic diatom bloom
Authors: Brunson John K. , Thukral Monica , Ryan John P. , Anderson Clarissa R. , Kolody Bethany C. , James Chase C. , Chavez Francisco P. , Leaw Chui Pin , Rabines Ariel J. , Venepally Pratap , Fussy Zoltan , Zheng Hong , Kudela Raphael M. , Smith G. Jason , Moore Bradley S. , Allen Andrew E.
Published: October 2024

In 2015, the largest recorded harmful algal bloom (HAB) occurred in the Northeast Pacific, causing nearly 100 million dollars in damages to fisheries and killing many protected marine mammals. Dominated by the toxic diatom
Pseudo-nitzschia australis
, this bloom produced high levels of the neurotoxin domoic acid (DA). Through molecular and transcriptional characterization of 52 near-weekly phytoplankton net-tow samples collected at a bloom hotspot in Monterey Bay, California, we identified active transcription of known DA biosynthesis (
dab
) genes from the three identified toxigenic species, including
P. australis
as the primary origin of toxicity. Elevated expression of silicon transporters (
sit1
) during the bloom supports the previously hypothesized role of dissolved silica (Si) exhaustion in contributing to bloom physiology and toxicity. We find that coexpression of the
dabA
and
sit1
genes serves as a robust predictor of DA one week in advance, potentially enabling the forecasting of DA-producing HABs. We additionally present evidence that low levels of iron could have colimited the diatom population along with low Si. Iron limitation represents an overlooked driver of both toxin production and ecological success of the low-iron-adapted
Pseudo-nitzschia
genus during the 2015 bloom, and increasing pervasiveness of iron limitation may fuel the escalating magnitude and frequency of toxic
Pseudo-nitzschia
blooms globally. Our results advance understanding of bloom physiology underlying toxin production, bloom prediction, and the impact of global change on toxic blooms.