bluuebunny/crossref_metadata_2025 huggingface dataset:
JWST’s PEARLS: 119 multiply imaged galaxies behind MACS0416, lensing properties of caustic crossing galaxies, and the relation between halo mass and number of globular clusters at z = 0.4
Authors: Diego Jose M. , Adams Nathan J. , Willner Steven P. , Harvey Tom , Broadhurst Tom , Cohen Seth H. , Jansen Rolf A. , Summers Jake , Windhorst Rogier A. , D’Silva Jordan C. J. , Koekemoer Anton M. , Coe Dan , Conselice Christopher J. , Driver Simon P. , Frye Brenda , Grogin Norman A. , Marshall Madeline A. , Nonino Mario , Ortiz Rafael , Pirzkal Nor , Robotham Aaron , Ryan Russell E. , Willmer Christopher N. A. , Yan Haojing , Sun Fengwu , Hainline Kevin , Berkheimer Jessica , del Carmen Polletta Maria , Zitrin Adi
Published: August 2024

We present a new lens model for the ɀ = 0.396 galaxy cluster MACS J0416.1 –2403 based on a previously known set of 77 spectroscop-ically confirmed, multiply imaged galaxies plus an additional set of 42 candidate multiply imaged galaxies from past HST and new JWST data. The new galaxies lack spectroscopic redshifts but have geometric and/or photometric redshift estimates that are presented here. The new model predicts magnifications and time delays for all multiple images. The full set of constraints totals 343, constituting the largest sample of multiple images lensed by a single cluster to date. Caustic-crossing galaxies lensed by this cluster are especially interesting. Some of these galaxies show transient events, most of which are interpreted as micro-lensing of stars at cosmological distances. These caustic-crossing arcs are expected to show similar events in future, deeper JWST observations. We provide time delay and magnification models for all these arcs. The time delays and the magnifications for different arcs are generally anti-correlated. In the major sub-halos of the cluster, the dark-matter mass from our lens model correlates well with the observed number of globular clusters, as expected from N-body simulations. This confirms earlier results, derived at lower redshifts, which suggest that globular clusters can be used as powerful mass proxies for the halo masses when lensing constraints are scarce or not available.
Linear polarization study of open clusters in the anticenter direction: Signature of the spiral arms
Authors: Uppal Namita , Ganesh Shashikiran , Pelgrims Vincent , Joshi Santosh , Sarkar Mrinmoy
Published: August 2024

Aims. Our objective is to investigate the distribution of dust and associated large-scale structures of the Galaxy using optical linear polarization measurements of various open clusters located at different distances in the Galactic anticenter direction.

Methods. We present R-band linear polarization observations of stars toward five open clusters: Kronberger 1, Berkeley 69, Berkeley 71, Berkeley 19, and King 8 in the anticenter direction. The polarization observations were carried out using the ARIES (Aryabhatta Research Institute of Observational Sciences) IMaging POLarimeter mounted on the 104 cm Sampurnanand telescope of ARIES, Nainital, making it the first study to target the polarization observations toward distant clusters (~6 kpc). We combined the observed polarization data with the distance information from the Gaia space telescope to infer the dust distribution along the line of sight.

Results. The variation in the degree of polarization and extinction with distance reveals multiple dust layers in each cluster direction. In addition, common foreground-dust layers detected toward different cluster directions highlight global features such as spiral arms. Our results show that the dust clouds at 2 kpc toward Berkeley 69 and Berkeley 71 coincide with the Perseus arm, while the dust layer at ~4 kpc toward the distant clusters Berkeley 19 and King 8 indicates the presence of the Outer arm. The large-scale dust distribution obtained by combining our polarization results with previous polarization studies of nearby open clusters suggests that the anticenter direction is characterized by a low-extinction homogeneous dust distribution with a somewhat uniform orientation of the plane-of-sky component of the magnetic field along the line of sight.

Conclusions. Our study demonstrates that polarization is useful as a tool for studying the large-scale dust distribution and structural features where kinematic distance methods are inadequate and cannot provide accurate distances to the dust clouds. The global dust distribution in the anticenter direction shows signatures of the intervening spiral arms.
X-ray view of dissipative warm corona in active galactic nuclei
Authors: Palit B. , Różańska A. , Petrucci P. O. , Gronkiewicz D. , Barnier S. , Bianchi S. , Ballantyne D. R. , Gianolli V. E. , Middei R. , Belmont R. , Ursini F.
Published: August 2024

Context. Detections of the X-ray spectra of active galactic nuclei (AGNs) typically reveal a noticeable excess of soft X-rays beyond the extrapolation of the power-law trend observed between 2 and 10 keV. However, the cause of this surplus remains unclear. In the scenario of soft Comptonization, observations suggest a warm corona temperature, ranging from 0.1 to 1 keV, and an optical depth of approximately 10 to 30. Furthermore, according to radiative constraints derived from spectral analyses employing Comptonization models, it has been suggested that most of the accretion power is released within the warm corona. At the same time, the disk beneath it is largely non-dissipative, mainly emitting the reprocessed radiation from the corona.

Aims. We tested the dissipative warm corona model using the radiative transfer code TITAN-NOAR on a sample of 82 XMM-Newton EPIC-pn observations of 21 AGNs. Based on a spectral modeling of the X-ray data, we aim to estimate the total amount of internal heating inside the warm corona on top of the accretion disk.

Methods. By modeling the 0.3–10 keV EPIC-pn spectra with the TITAN-NOAR model component, we estimated the internal heating and optical depth of the warm corona and checked their correlations with such global parameters as the hot corona spectral index, black hole mass, and accretion rate. From the model normalization, we computed the radial extent of the warm corona on top of the cold accretion disk.

Results. Our model infers the presence of dissipative warm corona, with optical depths distributed across the range of ∼6–30 and a total internal heating in the range of ∼1–29 × 10−23 erg s−1 cm3. We do not detect any variation between these properties and global properties, such as the black hole mass and accretion rate. The extent of the warm corona is spread across a broad range, from 7–408 gravitational radii, and we find that the warm corona is more extended for higher accretion rates.

Conclusions. Soft excess emission is ubiquitous across a wide mass range and accretion rate in AGNs. We confirm that the warm corona responsible for producing the soft X-ray excess is highly dissipative with greater optical depths being associated with lower internal heating and vice versa. The cold standard accretion disk regulates the extent of the warm corona.
Apsidal motion and TESS light curves of three southern close eccentric eclipsing binaries: GM Nor, V397 Pup, and PT Vel
Authors: Wolf M. , Zasche P. , Kára J. , Zejda M. , Janík J. , Mašek M. , Lehký M. , Merc J. , Richterková A. , Hanžl D. , Mikulášek Z. , de Villiers S. N. , Liška J.
Published: August 2024

The study of apsidal motion in eccentric eclipsing binaries provides an important observational test of theoretical models of stellar structure and evolution. New ground-based and space-based photometric data have been obtained and archival spectroscopic measurements were used in this study of three detached early-type and southern-hemisphere eccentric eclipsing binaries GM Nor (P = 1d​​.88, e = 0.05), V397 Pup (3d​​.00, 0.30), and PT Vel (1d​​.80, 0.12). Their TESS observations in several sectors have also been included and the corresponding light curves were solved using the PHOEBE code. As a result, new accurate photoelectric times of minimum light have been obtained. The newly completed O − C diagrams were analyzed using all reliable timings found in the literature and calculated using the TESS light curves. New or improved values for the elements of apsidal motion were obtained. Using ESO archive spectroscopy, for V397 Pup, the precise absolute parameters were newly derived: M1 = 3.076(35) M⊙, M2 = 2.306(35) M⊙, and R1 = 2.711(55) R⊙, R2 = 1.680(55) R⊙. For PT Vel the absolute dimensions were improved: M1 = 2.204(25) M⊙, M2 = 1.638(25) M⊙, and R1 = 2.108(30) R⊙, R2 = 1.605(30) R⊙. For GM Nor, the less accurate absolute parameters based on the light curve analysis were evaluated: M1 = 1.94(15) M⊙, M2 = 1.84(14) M⊙, and R1 = 2.27(20) R⊙, R2 = 2.25(20) R⊙. We found more precise and relatively short periods of apsidal motion of about 80, 335, and 160 years, along with the corresponding internal structure constants, log k2, –2.524, –2.361, and –2.563, for GM Nor, V397 Pup, and PT Vel, respectively. Relativistic effects are small but not negligible, making up to 10% of the total apsidal motion rate in all systems. No marks of the presence of the third body were revealed in the light curves, on the O − C diagrams, or in the reduced spectra of the eccentric systems studied here.
Uncovering the physical origin of the prominent Lyman-α emission and absorption in GS9422 at z = 5.943
Authors: Terp Chamilla , Heintz Kasper E. , Watson Darach , Brammer Gabriel , Carnall Adam , Witstok Joris , Smit Renske , Vejlgaard Simone
Published: August 2024

We present a comprehensive spectrophotometric analysis of galaxy GS9422 from the JADES GTO survey located at z = 5.943, anomalously showing a simultaneous strong Lyα emission feature and damped Lyα absorption (DLA), based on JWST NIRSpec and NIRCam observations. The best-fit modeling of the spectral energy distribution (SED) reveals a young, low-mass (log(M⋆/M⊙) = 7.80 ± 0.01) galaxy, with a mass-weighted mean age of the stellar population of (10.90−0.12+0.07) Myr. The identified strong nebular emission lines suggest a highly ionized (O32 = 59), low-metallicity (12 + log(O/H) = 7.78 ± 0.10) star-forming galaxy with a star-formation rate (SFR) of (8.2 ± 2.8) M⊙ yr−1 over a compact surface area Ae = 1.85 kpc2, typical for galaxies at this epoch. This corresponds to an intense SFR surface density of log(ΣSFR/M⊙ yr−1 kpc−2) = 1.14 ± 0.30. We carefully modeled the rest-frame UV NIRSpec Prism spectrum around the Lyα edge, finding that the Lyα emission-line redshift is consistent with the longer-wavelength recombination lines and an escape fraction of fesc, Lyα = 30% but that the broad DLA feature is not able to converge on the same redshift. Instead, our modeling suggests zabs = 5.40 ± 0.10, the exact redshift of a newly identified protocluster in nearby projection to the target galaxy. We argue that most of the H I gas producing the strong Lyα damping wing must be unassociated with the galaxy itself, and thus may indicate that we are probing the cold, dense circumcluster medium of this massive galaxy overdensity. These results provide an alternative solution to the recent claims of continuum nebular emission or an obscured active galactic nucleus dominating the rest-frame UV parts of the spectrum and provide further indications that strong DLAs might preferentially be associated with galaxy overdensities.
Argon X-ray absorption in the local interstellar medium
Authors: Gatuzz E. , Gorczyca T. W. , Hasoglu M. F. , García J. A. , Kallman T. R.
Published: August 2024

We present the first comprehensive analysis of the argon K-edge absorption region (3.1–4.2 Å) using high-resolution HETGS Chandra spectra of 33 low-mass X-ray binaries. Utilizing R-matrix theory, we computed new K photoabsorption cross sections for Ar I–Ar XVI species. For each X-ray source, we estimated column densities for the Ar I, Ar II, Ar III, Ar XVI, Ar XVII, and Ar XVIII ions, which trace the neutral, warm, and hot components of the gaseous Galactic interstellar medium. We examined their distribution as a function of Galactic latitude, longitude, and distances to the sources. However, no significant correlations were discerned among distances, Galactic latitude, or longitude. Future X-ray observatories will allow us to benchmark the atomic data as the main resonance lines will be resolved.
Short-term variability of the transitional pulsar candidate CXOU J110926.4−650224 from X-rays to infrared
Authors: Coti Zelati F. , de Martino D. , Dhillon V. S. , Marsh T. R. , Vincentelli F. , Campana S. , Torres D. F. , Papitto A. , Baglio M. C. , Miraval Zanon A. , Rea N. , Brink J. , Buckley D. A. H. , D’Avanzo P. , Illiano G. , Manca A. , Marino A.
Published: August 2024

CXOU J110926.4−650224 is a candidate transitional millisecond pulsar (tMSP) with X-ray and radio emission properties reminiscent of those observed in confirmed tMSPs in their X-ray ‘subluminous’ disc state. We present the results of observing campaigns that, for the first time, characterise the optical and near-infrared variability of this source and establish a connection with the mode-switching phenomenon observed in X-rays. The optical emission exhibited flickering activity, frequent dipping episodes where it appeared redder, and a multi-peaked flare where it was bluer. The variability pattern was strongly correlated with that of the X-ray emission. Each dip matched an X-ray low-mode episode, indicating that a significant portion of the optical emission originates from nearly the same region as the X-ray emission. The near-infrared emission also displayed remarkable variability, including a dip of 20 min in length during which it nearly vanished. Time-resolved optical spectroscopic observations reveal significant changes in the properties of emission lines from the disc and help infer the spectral type of the companion star to be between K0 and K5. We compare the properties of CXOU J110926.4−650224 with those of other tMSPs in the X-ray subluminous disc state and discuss our findings within the context of a recently proposed scenario that explains the phenomenology exhibited by the prototypical tMSP PSR J1023+0038.
First-principles study of the surface and optical properties of Heusler alloys Ru2XAl (X=Mn, Zr, Ti, Hf)
Authors: Hao Peichen , Liu Wenzhi , Wang Jian
Published: August 2024

Heusler alloys have excellent application prospects in fabricating spin electronic devices due to their remarkable properties. However, there is currently a lack of research on the surface properties and optical properties of Heusler alloys. In this study, we calculate the surface properties, band structure, and optical properties of four Ru-based Heusler alloys, Ru2XAl(X=Mn, Zr, Ti, Hf), using the first-principle density functional method within GGA approach. The surface properties calculation indicates that the (100) and (111) terminations with X atoms have stronger surface activities and more stable surface structures. The calculation results of the band structure confirm that the four Heusler alloys have metallic properties, which agree with the calculated results of their photoconductivity. In addition, the alloys Ru2TiAl, Ru2HfAl, and Ru2ZrAl exhibit peak reflectivity in the near-infrared spectrum, while Ru2MnAl manifests its highest reflectivity in the ultraviolet range.
Component factors and degree sum conditions in graphs
Authors: Qin Hui , Dai Guowei , Chen Yuan , Jin Ting , Yuan Yuan
Published: August 2024

For a set 𝒜
of connected graphs, an 𝒜-factor
is a spanning subgraph of a graph, whose connected components are isomorphic to graphs from the set 𝒜. An 𝒜-factor is also referred as a component factor. A graph G is called an (𝒜, m)-factor deleted graph if for every E′ ⊆ E(G) with |E′| = m, G − E′ admits an 𝒜-factor. A graph G is called an (𝒜, l)-factor critical graph if for every V′ ⊆ V (G) with |V′| = l, G − V′ admits an 𝒜-factor. Let m, l and k be three positive integers with k ≥ 2, and write
ℱ = {P2, C3, P5, 𝒯 (3)} and ℋ = {K1,1, K1,2, . . . , K1,k, 𝒯 (2k + 1)}, where 𝒯 (3) and 𝒯 (2k + 1) are two special families of trees. Inspired by finding a sufficient condition to check for the existence of path-factors with some special restraints, we focus on the sufficient conditions based on a graphic parameter called degree sum:
σκ(G) = min⁡X⊆V(G) {Σx∈XdG(x):X is an independent set of k vertices}.

In this article, we verify that: (i) an (l + 2)-connected graph G of order n is an (ℱ, l)-factor critical graph if
σ3(G) ≥ 6n+9l/5
;
(ii) a (2m + 1)-connected graph G of order n is an (ℱ, m)-factor deleted graph if σm+2(G) ≥ 6/5n
;
(iii) an (l + 2)-connected graph G of order n is an (ℋ, l)-factor critical graph if σ2k+1(G) ≥ 6n+(6k+3)l/2k+3
; (iv) a (2m + 1)-connected graph G of order n is an (ℋ, m)-factor deleted graph if σm+2(G) ≥ 6n/2k+3
.
Thermosphere model assessment for geomagnetic storms from 2001 to 2023
Authors: Bruinsma Sean , Laurens Sophie
Published: August 2024

We present an updated study for thermosphere model assessment under geomagnetic storm conditions, defined when the geomagnetic index ap = 80 or larger. Comparisons between five empirical models, NRLMSISE-00, JB2008, and three versions of DTM2020, and CHAMP, GRACE, GOCE, Swarm-A, and GRACE-FO neutral density data sets for 152 storms are presented. The storms are categorized according to ap, as single peak or multiple peaks. After applying a model debiasing procedure using the density data just before the onset of a storm, the models are on average only slightly biased, often only a few percent. This is an unexpected and reassuring result for these relatively simple models, which were fitted to different observations. The standard deviations of these averages are however up to 12% (1-sigma), which places the small biases into perspective. The smallest biases are achieved at the lowest altitude when comparing with GOCE data, and the highest for GRACE. The best results, i.e. smallest bias and standard deviation on average over all single-peak storms, over the entire 4-Phase storm period are obtained with DTM2020_Intermediate and DTM2020_Research models, while the oldest model, NRLMSISE-00, is the least precise. However, NRLMSISE-00 is the least biased when compared to multiple-peak storms. As could be expected, multiple-peak storms are reproduced with less precision than single-peak storms. The assessment reveals that model precision decreases with altitude, but that bias is independent of altitude, at least in the range covered by the data, 250–550 km.
Withaphysalin Derivatives from Iochroma arborescens Induce Antiproliferative and Antimigratory Activities in vitro
Authors: de Sá Rodrigo Elísio , de Araújo Gisele Santos , Machado Fabrício dos Santos , Souza Jessica Maria Teles , Barros Ayslan Batista , Pinto Francisco das Chagas Lima , Agostinho Joana Deyse Lima , Ayala Alejandro Pedro , Marinho Filho José Delano Barreto , Pessoa Otília Deusdênia Loiola , Araújo Ana Jérsia
Published: August 2024

Withanolides are steroidal lactones commonly found in plants of the Solanaceae family that have significant medicinal value. In this study, three withanolides extracted from Iochroma arborescens leaves were isolated and characterized. These included withaphysalin F (3) and two newly identified epimeric compounds: 18R- and 18S-O-methyl-withaphysalin F (1 and 2). Their structures were elucidated by NMR, IR, MS, CD, and X-ray diffraction analysis, and their potential against cell proliferation and migration was investigated. The cytotoxic assay revealed activity against different tumor and non-tumor cell lines. (18S)-O-methyl-withaphysalin F (2) presented cell death effects after at least 6 hours of exposure. MDA-MB-231 cells were exposed to 0.06 and 0.6 µM of (18S)-O-methyl-withaphysalin F (2), and reductions in cell adhesion, migration, and clonogenicity were observed. Morphological
analysis revealed negative regulation in filopodia, salience, and roughness, as well as alterations in cellular microarchitecture. These results provide clues as to the effects of (18S)-O-methyl-withaphysalin F (2), allowing new molecular modifications to improve potency and selectivity and increase our antineoplastic arsenal.
A Comprehensive Approach to C3a-Aryl-Substituted Hydroindole Alkaloids by Utilizing Enantioselective Gold Catalysis
Authors: Czekelius Constantin , Yu Jhen Kuei
Published: August 2024

A diversity-oriented total synthesis for Amaryllidaceae alkaloids incorporating the frequently found C3a-arylated hydroindole moiety was developed. Chiral-anion-induced gold(I) catalysis was employed for the cyclization of 1,4-diynes to the pyrrolidine and the installation of the all-carbon quaternary stereocenter. Both enantiomeric series of crinine-type alkaloids in high enantiopurity were accessible by this methodology. The formal synthesis of a wide range of Amaryllidaceae alkaloids is described, such as (+)-vitattine, (–)-epi-vitattine, (–)-elwesein, (–)-epi-elwesein, (–)-crinine, (–)-epi-crinine, (–)-buphanisine, (–)-flexinine, and (+)-gracilamine.
Imaging in Interventional Radiology: Applications of Contrast-Enhanced Ultrasound
Authors: HonShideler Curtis , Coffin Breyen , Guez David
Published: August 2024

This review explores the applications of contrast-enhanced ultrasound (CEUS) in interventional radiology, focusing on its role in endoleak detection after endovascular abdominal aortic aneurysm repair (EVAR), periprocedural thermal ablation guidance, and transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). CEUS offers a dynamic assessment for the detection of endoleak following EVAR, facilitating accurate diagnosis and classification. In periprocedural thermal ablation, CEUS enhances target lesion delineation with the visualization of real-time perfusion changes, optimizing treatment strategies and reducing residual tumor rates. Finally, CEUS has demonstrated efficacy in intraprocedural evaluation and postprocedural follow-up in TACE for HCC, offering early detection of residual tumor enhancement and providing an alternative for patients with contraindications to contrast-enhanced computed tomography or magnetic resonance imaging. Overall, CEUS is a versatile and valuable tool with many applications to offer interventional radiologists enhanced diagnostic capabilities and improved patient management.
Imaging for Hemorrhoidal Disease: Navigating Rectal Artery Embolization from Planning to Follow-up
Authors: Lindquist Jonathan , Hart James , Marchak Katherine , Bent Robinson Eduardo , Trivedi Premal
Published: August 2024

Hemorrhoid disease is very common, affecting greater than one-third of adults. Conservative management and several office-based procedures are useful in the treatment of internal hemorrhoids. Patients with refractory hemorrhoid disease have traditionally been treated with surgical hemorrhoidectomy. Rectal artery embolization has emerged as an alternative to surgical hemorrhoidectomy and has been shown to be safe and effective in case series and clinical trials completed over the past decade. Embolization has significantly less postprocedure pain when compared with surgical hemorrhoidectomy with similar outcomes. Pre- and postprocedure imaging are not routinely performed. Intraprocedural imaging consists of selective catheterization of the superior rectal arteries from the inferior mesenteric artery, and the middle rectal arteries from the internal iliac artery. The inferior rectal artery is seldom embolized due to the supply of the levator ani muscle and skin. To date, intermediate and large particles and fibered and nonfibered coils have been used successfully.
Aqueous ammonium-ion battery capacity boosted with electrode preparation
Authors: Johnson-Groh Mara
Published: August 2024

Orbital electron tuning and crystal engineering improves the energy storage capacity of non-flammable batteries.
Role of crystal orientation in attosecond photoinjection dynamics of germanium
Authors: Di Palo Nicola , Adamska Lyudmyla , Bonetti Simone , Inzani Giacomo , Talarico Matteo , Arias Velasco Marta , Dolso Gian Luca , Borrego-Varillas Rocío , Nisoli Mauro , Pittalis Stefano , Rozzi Carlo Andrea , Lucchini Matteo
Published: August 2024

Understanding photoinjection in semiconductors—a fundamental physical process—represents the first step toward devising new opto-electronic devices, capable of operating on unprecedented time scales. Fostered by the development of few-femtosecond, intense infrared pulses, and attosecond spectroscopy techniques, ultrafast charge injection in solids has been the subject of intense theoretical and experimental investigation. Recent results have shown that while under certain conditions photoinjection can be ascribed to a single, well-defined phenomenon, in a realistic multi-band semiconductor like Ge, several competing mechanisms determine the sub-cycle interaction of an intense light field with the atomic and electronic structure of matter. In this latter case, it is yet unclear how the complex balance between the different physical mechanisms is altered by the chosen interaction geometry, dictated by the relative orientation between the crystal lattice and the laser electric field direction. In this work, we investigate ultrafast photoinjection in a Ge monocrystalline sample with attosecond temporal resolution under two distinct orientations. Our combined theoretical and experimental effort suggests that the physical mechanisms determining carrier excitation in Ge are largely robust against crystal rotation. Nevertheless, the different alignment between the laser field and the crystal unit cell causes non-negligible changes in the momentum distribution of the excited carriers and their injection yield. Further experiments are needed to clarify whether the crystal orientation can be used to tune the photoinjection of carriers in a semiconductor at these extreme time scales.
Spin waves in ferrimagnets near the angular magnetization compensation temperature: A micromagnetic study
Authors: Sánchez-Tejerina Luis , Osuna Ruiz David , Martínez Eduardo , López Díaz Luis , Raposo Víctor , Alejos Óscar
Published: August 2024

Spin wave propagation along a ferrimagnetic strip with out-of-plane magnetization is studied by means of micromagnetic simulations. The ferrimagnetic material is considered to be formed by two antiferromagnetically coupled sub-lattices. Two critical temperatures can be defined for such systems: that of magnetization compensation and that of angular momentum compensation, both different due to distinct Landé factors for each sub-lattice. Spin waves in the strip are excited by a spin current injected at one of its edges. The obtained dispersion diagrams show exchange-dominated forward volume spin waves. For a given excitation frequency, the Néel vector describes highly eccentric orbits, the eccentricity depending on temperature, whose semi-major axis is oriented differently at distinct locations on the FiM strip.
Efficient laser-driven proton acceleration from a petawatt contrast-enhanced second harmonic mixed-glass laser system
Authors: Gonzalez-Izquierdo B. , Fischer P. , Touati M. , Hartmann J. , Speicher M. , Scutelnic V. , Rivas D. E. , Bodini G. , Fazzini A. , Günther M. M. , Härle A. K. , Kenney K. , Schork E. , Bruce S. , Spinks M. , Quevedo H. J. , Helal A. , Medina M. , Gaul E. , Ruhl H. , Schollmeier M. , Steinke S. , Korn G.
Published: August 2024

Efficient laser-driven plasma acceleration of ion beams requires precision control of the target–plasma profile, which is crucial to optimize the laser energy transfer. Along the laser propagation direction, this can be achieved by tailoring the temporal structure of the laser pulse. We show for the first time that frequency-doubling of a short pulse (hundreds-femtosecond range) petawatt-class mixed-glass laser system, which results in temporal intensity contrast enhancement, enables surface and volumetric laser–energy coupling, and the acceleration of proton beams from few-nanometer-thick foil targets. Experimentally, maximum ion energies and laser-to-proton energy conversion efficiencies were found to be both maximized at optimum laser and target conditions manifested when the normalized target density nearly equalizes the normalized laser vector potential, which is in agreement with theory and simulations. These signatures are recognized as a unique indication of the interaction between ultra-intense laser pulses with high temporal intensity contrast and ultra-thin nanometer-scale targets. Transverse modulations of accelerated proton beams in the form of bubble- and ring-like structures measured in the thinnest targets provide additional evidence of volumetric laser-driven particle acceleration regimes and transitional features in ultra-thin foil targets specific to laser–plasma interactions characterized by a high temporal intensity contrast. These results open avenues in the generation of high contrast laser pulses from short-pulse-femtosecond petawatt mixed-glass laser systems and demonstrate the feasibility of this technique for applications requiring high laser intensity contrast with high efficiency.
Artificial excitation and propagation of ultra-low frequency signals in the polar ionosphere
Authors: Li Yong , Li Hui , Wu Jian , Lyu Xingbao , Chai Yan , Yuan Chengxun , Zhou Zhongxiang
Published: August 2024

This paper has established a relatively comprehensive model for ultra-low frequency (ULF) current induced by thermal pressure gradients and its propagation. In the ULF current excitation model, we decomposed the current into a constant term unaffected by altitude and a product with a function significantly influenced by altitude. Combining this with the EISCAT background, we determined that for modulation frequencies below 5 Hz, the optimal height for ULF current excitation corresponds to the critical frequency height. We calculated the ionospheric currents at heating altitudes of 332 km for modulation frequencies of 5 Hz; the corresponding maximum currents were 1.03 × 10−10 A·m−2. By incorporating the current into the ULF waves propagation model based on magnetoionic theory, we found that the electromagnetic field energy is mainly concentrated in the horizontal direction, indicating that the energy primarily propagates outward through magnetosonic waves. The dominant components are the electric field component Ey and the magnetic field component Bz, whose maximum values reached 1.1 μV·m−1 and 1.5 pT. Unfortunately, magnetosonic waves cannot propagate downward due to the sharp variation in the real part of the refractive index between 200 and 300 km. However, the shear Alfvén waves component By can propagate downward, and there is still an intensity of approximately 0.1 pT at the bottom of the ionosphere, which is because the refractive index of shear Alfvén waves is most uniform in the parallel magnetic field direction, allowing By to propagate parallel to the magnetic field effectively.
A pragmatic data processing system for large resistive sensor arrays
Authors: Sun X. , Zhang M.
Published: August 2024

Large resistive sensor arrays (RSAs) show great potential in tactile perception. However, the large number of sensors can result in great hardware overhead and bring difficulties for acquiring and processing mass data timely in transient measurement applications. This paper implements a field programmable gate array (FPGA)-based data processing system for a large RSA of 96 × 96, which shows good power consumption and high-speed wireless data update. For crosstalk-free measure, the zero potential method is improved with bus switches, leading to fewer operational amplifiers required and less negative power consumption. A real-time embedded data processing system is realized by FPGA for excellent parallel processing ability. A high-speed wireless transfer scheme with automatic regulated transfer size is proposed and realized by a wireless fidelity module, which allows timely data analysis at the remote end. Moreover, fault identification of RSAs fabricated by micro-electromechanical system technology is achieved. Tests carried out on a 32 × 32 RSA show that the total power consumption is 2209 mW, including 1261 mW of processors and 948 mW of readout circuits, corresponding to 2.15 mW/pixel. The total negative power consumption of 549 mW has been reduced by 50% compared with the zero potential method. The scanning speed is 400 fps, and the wireless transfer speed is up to 120 fps when the transceiver and receiver are 5 m apart.
Gigahertz and terahertz transistors for 5G, 6G, and beyond mobile communication systems
Authors: Liou Juin J. , Ziegler Martin , Schwierz Frank
Published: August 2024

Mankind is currently living in the era of mobile communication. Mobile communication encompasses almost all areas of our daily life and is heavily used in most sectors of economy, including agriculture, healthcare, education, and so on. With mobile devices such as smart phones, people can connect to any other people somewhere on the earth, can access huge databases via the internet, stream videos and movies, to name just a few of the many mobile services that are routinely used in the early 2020s. Artificial intelligence, virtual reality, and other emerging new applications will further boost the importance of mobile communication. It is a general trend that with progressing evolution of mobile communication, the amount of data to be transmitted wirelessly increases rapidly and continuously. To enable this, a suitable well-performing hardware infrastructure is needed. The hardware used so far in the successively introduced generations of systems for mobile communication is essentially based on fast transistors. We designate these transistors as gigahertz (GHz)–terahertz (THz) transistors, as the high data rates to be transferred require an electronic hardware operating properly at frequencies in the GHz–THz range. The present paper provides a comprehensive in-depth discussion of these transistors. After a short survey of the evolution of mobile communication systems, the different categories and classes of GHz–THz transistors are introduced, relevant transistor performance measures called figures of merit are defined, issues of transistor design are dealt with, and general design rules for GHz–THz transistors are established. This is followed by a tour through the evolution of these transistors, starting in the 1950s, when the first transistors with GHz capabilities were demonstrated, up to the latest developments since the turn of the millennium and to the state-of-the-art in mid-2024. The discussion includes evolutionary advances as well as true breakthroughs, both contributing to the significant performance improvements achieved over the years. Furthermore, some research activities on GHz–THz transistors, which, unfortunately, led to a dead end as well as ongoing efforts with still unclear outcome are presented and the approaching limits of transistor performance are critically examined. Finally, we take a short view on alternative hardware options for mobile communication systems beyond the limits of transistors.
First-principles calculations of cubic boron arsenide surfaces
Authors: Sun Yuxuan , Niu Yinge , Zhang Lingxue , Zhang Jiaxin , Quhe Ruge
Published: August 2024

The properties of cubic boron arsenide (c-BAs) (100), (110), and (111) surfaces are investigated by performing first-principles calculations using the slab and Green's function surface models with different terminals. The (111) surface with As-termination is found to be the most stable structure among the studied surfaces, with its lowest surface energy (1.70–1.92 J m−2) and largest surface density (20.24 nm−2). The electronic affinity of these surfaces lie in the range 4.62–6.17 eV, which is higher than that of common semiconductor materials, such as silicon (4.05 eV) and germanium (4.13 eV), implying that the electrons at the bottom of the conduction band require more energy to escape. The surface states of the structures with As-termination in the surface band structures are generally more numerous and extended than those with B-termination. The absorption peak of the bulk c-BAs is located in the ultraviolet region, and the light absorption ranges of the surfaces are significantly extended compared with the bulk c-BAs, due to the surface states inside the bandgap.
Elucidating phonon dephasing mechanisms in layered perovskites with coherent Raman spectroscopies
Authors: Gan Zijian , Gloor Camryn J. , Yan Liang , Zhong Xiaowei , You Wei , Moran Andrew M.
Published: August 2024

Organic–inorganic hybrid perovskite quantum wells exhibit electronic structures with properties intermediate between those of inorganic semiconductors and molecular crystals. In these systems, periodic layers of organic spacer molecules occupy the interstitial spaces between perovskite sheets, thereby confining electronic excitations to two dimensions. Here, we investigate spectroscopic line broadening mechanisms for phonons coupled to excitons in lead-iodide layered perovskites with phenyl ethyl ammonium (PEA) and azobenzene ethyl ammonium (AzoEA) spacer cations. Using a modified Elliot line shape analysis for the absorbance and photoluminescence spectra, polaron binding energies of 11.2 and 17.5 meV are calculated for (PEA)2PbI4 and (AzoEA)2PbI4, respectively. To determine whether the polaron stabilization processes influence the dephasing mechanisms of coupled phonons, five-pulse coherent Raman spectroscopies are applied to the two systems under electronically resonant conditions. The prominence of inhomogeneous line broadening mechanisms detected in (AzoEA)2PbI4 suggests that thermal fluctuations involving the deformable organic phase broaden the distributions of phonon frequencies within the quantum wells. In addition, our data indicate that polaron stabilization primarily involves photoinduced reorganization of the organic phases for both systems, whereas the impulsively excited phonons represent less than 10% of the total polaron binding energy. The signal generation mechanisms associated with our fifth-order coherent Raman experiments are explored with a perturbative model in which cumulant expansions are used to account for time-coincident vibrational dephasing and polaron stabilization processes.
Cooperative operation optimization for rural multi-microgrid and county-integrated energy operators considering typical energy scenarios
Authors: Zhang Lihui , Ruan Zefeng , Li Songrui , Wu Sijie
Published: August 2024

Despite being rich in renewable energy, China's rural areas are backwards in terms of energy use. Rural multi-microgrid cooperative operation optimization can effectively promote renewable energy use in rural areas. Many different microgrid energy scenarios have been developed for rural areas of China, and they have different resource endowments and unit compositions. Moreover, frequent power-related interactions occur between counties and villages. This study analyzes four typical microgrid energy scenarios in rural areas of China and optimizes their synergistic operation based on county-integrated energy operators. First, a mathematical model of rural microgrids for four energy scenarios and a trading mechanism between rural multi-microgrid and county-integrated energy operators were constructed. Subsequently, an upper-level optimization model that minimizes operating costs was developed for the county-integrated energy operator. A low-level optimization model was developed for rural multi-microgrid usage, and it minimized the operating costs. Finally, Stackelberg game theory was utilized to resolve the optimization issue. The results showed that the cooperative optimization of rural multi-microgrid and county-integrated energy operations can reduce the operating costs of both parties compared to that when each subject is operating alone. This optimization reduced the rural multi-microgrid cost from 12 773.64 yuan to 11 508.67 yuan and county-integrated energy operator cost from 3898.37 yuan to 1581.79 yuan. Moreover, it reduced both parties' dependence on external power grids; increased the self-balancing capacity of the rural multi-microgrid and county-integrated energy operator from 0.424 to 0.715 and 0.694 to 0.852, respectively; substantially increased the capacity of renewable energy consumption through power interaction; and reduced the risk of fluctuations in system operating costs.
Photothermal phase modulation in a gas-immersed optical nanofiber
Authors: Liao Hanyu , Qi Yun , Jiang Shoulin , Ho Hoi Lut , Bao Haihong , Jin Wei
Published: August 2024

We report the observation and theoretical analysis of photothermal phase modulation in an optical nanofiber (NF) immersed in light-absorbing gas. The phase modulation arises from the contrasting photothermal processes experienced by the mode field within and outside the NF, which exhibits significant wavelength and pressure dependence in the nanoscale waveguides. By designing the diameter of the NF, the photothermal phase modulation can be readily controlled, and a nullification of phase modulation is achieved at a specific wavelength. Experiments on NFs with different diameters demonstrated pressure-controllable phase modulation up to 0.058π rad/mW, potentially allowing the development of nanoscale all-optical modulators and sensors with optimal performance.
Silver vanadate nanoparticles: Green synthesis, enhanced photocatalytic and antibacterial activity
Authors: Prakruthi R. , Deepakumari H. N. , Revanasiddappa H. D. , Alfaisal Faisal M. , Alam Shamshad , Majdi Hasan Sh. , Amir khan Mohammad , Ukkund Shareefraza J.
Published: August 2024

Nanotechnology provides a very good chance to research and develop multipurpose nanomaterials because of their smaller size, larger surface area, low cost, and nanoscale materials, which are auspicious tools for many biological applications. The AgVO3 nanoparticle synthesis employing plant extract has offered an eco-friendly alternative for the industry. Literature survey shows that no research has been performed on AgVO3 using jackfruit; hence, we prepared AgVO3 using jackfruit extract as a reducing agent by a simple, easy, and eco-friendly precipitation method. The characterization techniques used for synthesized AgVO3 nanoparticles were x-ray diffraction analysis, which determines the monoclinic structure of synthesized AgVO3 nanoparticles; Fourier transform infrared spectroscopy, which shows the bonding of V–O–V; and scanning electron microscopy and energy dispersive spectra (EDS), which confirm the size, shape, purity, and elemental composition. Brunauer–Emmett–Teller analysis confirms the pore size, pore volume, and surface area of synthesized AgVO3 nanoparticles, Raman studies show the crystalline property, and UV–Vis studies give information about the material’s formation and optical properties. The bandgap was calculated to be 2.54 eV. Furthermore, the photocatalytic studies show 98.14% degradation in 180 min using MB dye. We also performed scavenger studies for detection of OH· radicals and recyclability. Gram-negative (Klebsiella pneumonia and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus subtilis) micro-organisms were used to determine the antimicrobial characteristics. The full analysis verifies AgVO3’s antibacterial activity against both gram-negative and gram-positive bacteria, as well as its excellent photocatalytic activities for the degradation of the organic dye methylene blue with a high degree of recyclability.
Enhancing terahertz magneto-optical effects in wafer-scale RIG single crystal thick films with anti-reflective coatings for improved transmittance
Authors: Xue Qiang , Zhang Yuan-Jing , Yang Qing-Hui , Zhang Huai-Wu , Wen Qi-Ye
Published: August 2024

Wafer-scale rare-earth iron garnet (RIG) single crystal thick films were fabricated on 3-in. gadolinium gallium garnet (GGG) substrates using liquid phase epitaxy. The terahertz transmittance of the RIG crystals improved after removing the GGG substrate by polishing. The time-domain spectra at Terahertz (THz) frequencies indicate the existence of a magneto-optical effect in RIG samples. The results indicate that the RIG samples exhibit a high refractive index of ∼4.50 within the 0.1–1.0 THz frequency range, a transmittance of around 40%, and an absorption rate of only 10–50 cm−1. The Faraday rotation angles of the thick single-crystal films of the RIG samples were measured using a THz-TDS system. The RIG has a thickness of ∼330 μm. The Faraday rotation angles of RIG crystals at THz frequencies can reach up to 16° when an external magnetic field of 0.18 T is applied. The Verdet constants of the RIG sample were calculated to be ∼120°/mm/T. To improve the transmittance of the RIG sample, epoxy resin and polymethylpentene (TPX) were used as anti-reflective films. The transmittance of the RIG sample increased by ∼5% for the 80 μm thick epoxy and about 10% for the 320 μm thick TPX. Therefore, this RIG single crystal thick film can achieve a low loss, a high transmittance, and a strong magneto-optical effect in the terahertz region with the cooperation of a reflection-reducing film. It is expected to have wide applications in terahertz magnetic polarization conversion, non-reciprocal phase shifters, and isolators.
Flexible optoelectronic N-I-P synaptic device with visible spectrum perception for energy-efficient artificial vision and efferent neuromuscular system
Authors: Wei Huanhuan , Fu Can , Yang Wen , He Gang , Guo Jiahao , Ni Yao , Gong Jiangdong
Published: August 2024

We have designed a flexible photoelectric artificial synapse with an oxide/mixed perovskite/polymer N-I-P structure that exhibits essential synaptic plasticity. Formamidinium lead triiodide FAPbI3 perovskite doped with bromine and methylammonium (FAxMA1−xPbI2Br) is employed as the intrinsic layer to improve the optical properties of devices. Without requiring a power source in reaction to outside optical spikes, multiple pulse-dependent plasticity is reproduced on the synaptic devices, and the image's edges are sharpened using high-pass filtering. Additionally, the classical conditioning and spatiotemporal learning are copied under the electric pulse excitation. Significant negative differential resistance is evident, even after 1500 flex/flat mechanical operation. The recognition rate of letters in the visual system is as high as 92%, and the walking distance in the efferent neuromuscular system is controllable. The flexible optoelectronic N-I-P synaptic device is designed to facilitate energy-efficient information processing for neuromorphic computing.
Large magnetoresistance and de Haas–van Alphen oscillations in NbNiTe5 originated from nontrivial band topology
Authors: Singh Haribrahma , Kant Mishra Prabuddha , Kumar Ganguli Ashok
Published: August 2024

Quasi-one-dimensional topological materials have emerged as a captivating area of research due to their interesting electronic properties and potential applications. NbNiTe5 is one such quasi-1D material. In this work, we report the synthesis, structural characterization, and comprehensive investigation of the electrical transport and magnetic properties of NbNiTe5. NbNiTe5 crystallizes in the orthorhombic crystal system with the Cmcm space group. Experimental studies have uncovered metallic nature with a remarkably high residual resistivity ratio of 103, along with intriguing spin–orbit interaction-driven nonsaturating magnetotransport properties at low temperatures. A meticulous analysis incorporating magnetoconductivity measurements unveils signatures of weak anti-localization analyzed by using the Hikami–Larkin–Nagaoka formula. Furthermore, the de Haas–van Alphen oscillations demonstrate the high mobility of charge carriers with a significantly low effective mass at five frequencies: Fα=84.82 T, Fβ=131.21 T, Fγ=242.36 T, Fδ=31.93 T, and Fδ′=162.33 T. In light of these collective findings, NbNiTe5 can be defined as a quasi-1D topological semimetal.