High Mass Density Research Articles

Enhanced removal of recalcitrant naphthenic acids through electro-cocatalytic activation of peracetic acid: Synergistic effects of multiple factors

Herein, a peracetic acid (PAA)-based electro-cocatalytic system (EC/PAA/Fe(III)) has been established for efficient degradation of 1-adamantanecarboxylic acid (ACA), which is a typical model chemical for naphthenic acids (NAs) that are abundantly present in petroleum industrial wastewater. The electric field greatly boosted the regeneration of Fe(II) to activate PAA in the system, resulting in 99.8 % removal for ACA within 20-min reaction time, with kobs of 0.3451 min−1. Results of quenching and chemical probe experiments verified the production of •CH3, CH3C(O)O•, •OH and FeIVO2+, in the EC/PAA/Fe(III) system with the FeIVO2+ identified as the primary contributor to ACA removal. The H2O2 present in the PAA solution enhanced the activation of PAA by promoting Fe(II) generation, thereby significantly improving ACA degradation efficiency. The ACA degradation byproducts and pathways were identified using the results of high resolution mass spectrometry analysis and density functional theory (DFT) calculations. Decarboxylation, hydroxy substitution, and carbonyl substitution reactions were predominant oxidation pathways of ACA decontamination. The EC/PAA/Fe(III) system demonstrated resilient degradation performance under the influence of anions and the natural water matrix for effective degradation of the commercial NAs mixture. Overall, the EC/PAA/Fe(III) system has been established with effectiveness and reliability for future remediation of NAs in petroleum industrial wastewater.

Fluorescence and colorimetric dual-mode sensing of copper ions and fingerprint visualization by benzimidazole derivatives

In this paper, the molecular fluorescence probe H containing an imidazole structure was designed and synthesized by forming a ring between two amino groups and one aldehyde group. The synthesized probe H exhibits a Stokes shift of 144 nm with fluorescence emission at 555 nm and excitation at 411 nm. The fluorescence of probe H was quenched by the addition of Cu2+ and accompanied a red-shift of ultraviolet–visible (UV–Vis) absorption spectrum. Probe H reveals good selectivity and high sensitivity to Cu2+ in the fluorescence and UV–Vis absorption spectrum. And the limit of detection (LOD) for Cu2+ by fluorescence and UV–Vis spectrum methods were 0.14 nmol L−1 and 1.34 μmol L−1, respectively. The binding ratio of probe H and Cu2+ is 1:1 according to the Job’s plot equation. High resolution mass spectrometry (HRMS) and density function theory (DFT) calculations proved that the solvent acetonitrile and anionic chloride ion participated in the formation of H-Cu2+ complex. Furthermore, the established fluorescence analytical method was successfully applied for the detection of Cu2+ and spiked recovery experiments in tap water and mineral water. In addition, the probe exhibited outstanding solid-state fluorescence because of its excellently planar structure, and displayed a secondary fingerprint structure in the application of fingerprint detection.

Multiband Analysis of Strong Gravitationally Lensed Post-blue Nugget Candidates from the Kilo-degree Survey

During the early stages of galaxy evolution, a significant fraction of galaxies undergo a transitional phase between the “blue nugget” systems, which arise from the compaction of large, active star-forming disks, and the “red nuggets,” which are red and passive compact galaxies. These objects are typically only observable with space telescopes, and detailed studies of their size, mass, and stellar population parameters have been conducted on relatively small samples. Strong gravitational lensing can offer a new opportunity to study them in detail, even with ground-based observations. In this study, we present the first six bona fide samples of strongly lensed post-blue nugget (pBN) galaxies, which were discovered in the Kilo Degree Survey. By using the lensing-magnified luminosity from optical and near-infrared bands, we have derived robust structural and stellar population properties of the multiple images of the background sources. The pBN galaxies have very small sizes of R eff < 1.3 kpc, high mass density inside 1 kpc of log(Σ1/M⊙kpc−2)>9.3 , and low specific star formation rates of log(sSFRGyr-1)≲0 , The size–mass and Σ1–mass relations of this sample are consistent with those of the red nuggets, while their sSFR is close to the lower end of compact star-forming blue nugget systems at the same redshift, suggesting a clear evolutionary link between them.

Hierarchical ferrous medium entropy with heterogeneous precipitates embedded in core-shell grain structure for superior mechanical properties

Superalloys designed for high-temperature applications, featuring a face-centered cubic matrix and L12 precipitates, have shown excellent tensile properties at both room and elevated temperatures. However, the substantial Ni and Co, necessary for generating a high fraction of the ordered L12 phase within the matrix, results in high mass density and cost, subsequently limiting their widespread industrial application. It is important to increase Fe content over Ni and Co while preserving outstanding mechanical properties at ambient and high temperatures. In this study, we propose a novel approach to introduce a hierarchical structure in a 60-at%-Fe-based medium entropy alloy. The heterogeneous nano-precipitates embedded in harmonic (core-shell) grain structure reinforce mechanical contrast between soft and hard domains, achieving an excellent heterostructure. The present alloy incorporates hierarchical heterogeneity at multi-scales, combining heterogeneous grain at micrometers, precipitates at tens of nanometers, and elemental fluctuation at nanometers. This hierarchical structure shows superior mechanical properties at room and high temperatures comparable to those of conventional superalloys. Further, the high content of Fe in this alloy system shows excellent performance in alloy cost and mass density. This work suggests the unique hierarchical heterostructure to overcome the trade-off dilemma in alloy cost, mass density, and mechanical properties in room/elevated temperatures.

JWST NIRSpec Spectroscopy of the Remarkable Bright Galaxy GHZ2/GLASS-z12 at Redshift 12.34

We spectroscopically confirm the M UV = −20.5 mag galaxy GHZ2/GLASS-z12 to be at redshift z = 12.34. The source was selected via NIRCam photometry in GLASS-JWST Early Release Science data, providing the first evidence of a surprising abundance of bright galaxies at z ≳ 10. The NIRSpec PRISM spectrum shows detections of N iv, C iv, He ii, O iii, C iii, O ii, and Ne iii lines and the first detection at high redshift of the O iii Bowen fluorescence line at 3133 Å rest frame. The prominent C iv line with rest-frame equivalent width (EW) ≈ 46 Å puts GHZ2 in the category of extreme C iv emitters. GHZ2 displays UV lines with EWs that are only found in active galactic nuclei (AGNs) or composite objects at low/intermediate redshifts. The UV line-intensity ratios are compatible with both AGNs and star formation in a low-metallicity environment, with the low limit on the [Ne iv]/[N iv] ratio favoring a stellar origin of the ionizing photons. We discuss a possible scenario in which the high ionizing output is due to low-metallicity stars forming in a dense environment. We estimate a metallicity ≲0.1 Z/Z ⊙, a high ionization parameter log U > −2, a N/O abundance 4–5 times the solar value, and a subsolar C/O ratio similar to the recently discovered class of nitrogen-enhanced objects. Considering its abundance patterns and the high stellar mass density (104 M ⊙ pc−2), GHZ2 is an ideal formation site for the progenitors of today's globular clusters. The remarkable brightness of GHZ2 makes it a “Rosetta stone” for understanding the physics of galaxy formation within just 360 Myr after the Big Bang.

Constraints on Primordial Magnetic Fields from High Redshift Stellar Mass Density

Primordial magnetic fields (PMFs) play a pivotal role in influencing small-scale fluctuations within the primordial density field, thereby enhancing the matter power spectrum within the context of the ΛCDM model at small scales. These amplified fluctuations accelerate the early formation of galactic halos and stars, which can be observed through advanced high-redshift observational techniques. Therefore, stellar mass density (SMD) observations, which provide significant opportunities for detailed studies of galaxies at small scales and high redshifts, offer a novel perspective on small-scale cosmic phenomena and constrain the characteristics of PMFs. In this study, we compile 14 SMD data points at redshifts z > 6 and derive stringent constraints on the parameters of PMFs, which include the amplitude of the magnetic field at a characteristic scale of λ = 1 Mpc, denoted as B 0, and the spectral index of the magnetic field power spectrum, n B . At 95% confidence level, we establish upper limits of B 0 < 4.44 nG and n B < −2.24, along with a star formation efficiency of approximately f*0∼0.1 . If we fix n B at specific values, such as −2.85, −2.9, and −2.95, the 95% upper limits for the amplitude of the magnetic field can be constrained to 1.33, 2.21, and 3.90 nG, respectively. Finally, we attempt to interpret recent early observations provided by the James Webb Space Telescope using the theory of PMFs and find that by selecting appropriate PMF parameters, it is possible to explain these results without significantly increasing the star formation efficiency.

Bioarchitectonic Nanophotonics by Replication and Systolic Miniaturization of Natural Forms.

The mimesis of biological mechanisms by artificial devices constitutes the modern, rapidly expanding, multidisciplinary biomimetics sector. In the broader bioinspiration perspective, however, bioarchitectures may perform independent functions without necessarily mimicking their biological generators. In this paper, we explore such Bioarchitectonic notions and demonstrate three-dimensional photonics by the exact replication of insect organs using ultra-porous silica aerogels. The subsequent conformal systolic transformation yields their miniaturized affine 'clones' having higher mass density and refractive index. Focusing on the paradigms of ommatidia, the compound eye of the hornet Vespa crabro flavofasciata and the microtrichia of the scarab Protaetia cuprea phoebe, we fabricate their aerogel replicas and derivative clones and investigate their photonic functionalities. Ultralight aerogel microlens arrays are proven to be functional photonic devices having a focal length f ~ 1000 μm and f-number f/30 in the visible spectrum. Stepwise systolic transformation yields denser and affine functional elements, ultimately fused silica clones, exhibiting strong focusing properties due to their very short focal length of f ~ 35 μm and f/3.5. The fabricated transparent aerogel and xerogel replicas of microtrichia demonstrate a remarkable optical waveguiding performance, delivering light to their sub-100 nm nanotips. Dense fused silica conical clones deliver light through sub-50 nm nanotips, enabling nanoscale light-matter interactions. Super-resolution bioarchitectonics offers new and alternative tools and promises novel developments and applications in nanophotonics and other nanotechnology sectors.

Exploring the dark energy equation of state with JWST

Observations from the James Webb Space Telescope (JWST) have unveiled several galaxies with stellar masses M∗≳1010M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M_*\\gtrsim 10^{10} M_\\odot$$\\end{document} at redshifts 7.4≲z≲9.1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$7.4\\lesssim z\\lesssim 9.1$$\\end{document}. These remarkable findings indicate an unexpectedly high stellar mass density, which contradicts the prediction of the ΛCDM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda \\rm{CDM}$$\\end{document} model. Our study utilizes the Chevallier–Polarski–Linder (CPL) parameterization, one of the dynamic dark energy models, to probe the role of dark energy on shaping galaxy formation. By considering varying star formation efficiencies within this framework, our analysis demonstrates that in a universe with a higher proportion of dark energy, more massive galaxies are formed at high redshifts, given a fixed perturbation amplitude observed today. These intriguing results highlight the promising prospect of revealing the nature of dark energy by analyzing the high-redshift massive galaxies.

Malignant Phyllodes Tumour with Heterologous Osteosarcomatous differentiation and Osteoclast-like giant cells: Case Report of an uncommon neoplasm

Background: Phyllodes tumour (PT), an uncommon fibroepithelial neoplasm accounts for less than 1% of all primary tumours of the breast. MPT with osseous differentiation often gets misdiagnosed on imaging as benign giant calcifications resulting in treatment delay. We describe a rare case of MPT with heterologous osteosarcomatous differentiation and osteoclast-like giant cells and review the literature to discuss clinical-radiological findings, differential diagnosis and treatment options. Case Presentation: A 34-year-old female presented with a right breast lump. Mammography showed a high-density irregular mass with amorphous dense calcification, suggesting neoplastic aetiology. Preoperative core needle biopsy raised the possibility of a phyllodes tumour versus giant cell tumour. Wide local excision was performed to confirm the diagnosis which revealed the presence of a biphasic tumour with osteoid-like matrix and numerous osteoclastic giant cells. Immunohistochemistry was used to rule out metaplastic carcinoma or carcinosarcoma. The stromal cells were negative for panCK and P63 and positive for vimentin, CD10 and BCL-2. The osseous component was positive for Osteonectin and SATB2. Thus, a final diagnosis of malignant phyllodes tumour with heterologous osteosarcomatous differentiation and osteoclast-like giant cells was made. Conclusion: MPT with osteosarcomatous differentiation is a rare and challenging entity associated with a poor clinical outcome. Accurate diagnosis requires a multidisciplinary approach involving breast surgeons, pathologists and radiologists with careful histopathological examination. Wide local excision with close surveillance is crucial for timely detection of tumour recurrence and metastasis.

Exact solution for mode shapes of cracked nonuniform axially functionally graded beams

This paper established the exact formulas for mode shapes of cracked nonuniform axially functionally graded (AFG) beams. The formula of the mode shape of cracked nonuniform AFG beam is derived in the form of a power presented as a recurrent relation. The power series solution of cracked beam is the same with the intact beam where the effect of cracks contributes to only the first four coefficients of the power series. The derivation of the formula of mode shapes is presented in details. Numerical simulations show that these effects on the natural frequency and mode shape are quite significant. The natural frequency and mode shape are more sensitive to cracks located at positions with low elastic modulus, small cross section and high mass density. For the case of tapered AFG cantilever beam, it is important to consider not only cracks located close to the fixed end but also cracks located close to the free end, especially when the free end has lower elastic modulus and higher mass density.

Novel Class of Crystal/Glass Ultrafine Nanolaminates with Large and Tunable Mechanical Properties.

The control of local heterogeneities in metallic glasses (MGs) represents an emerging field to improve their plasticity, preventing the propagation of catastrophic shear bands (SBs) responsible for the macroscopically brittle failure. To date, a nanoengineered approach aimed at finely tuning local heterogeneities controlling SB nucleation and propagation is still missing, hindering the potential to develop MGs with large and tunable strength/ductility balance and controlled deformation behavior. In this work, we exploited the potential of pulsed laser deposition (PLD) to synthesize a novel class of crystal/glass ultrafine nanolaminates (U-NLs) in which a ∼4 nm thick crystalline Al separates 6 and 9 nm thick Zr50Cu50 glass nanolayers, while reporting a high density of sharp interfaces and large chemical intermixing. In addition, we tune the morphology by synthesizing compact and nanogranular U-NLs, exploiting, respectively, atom-by-atom or cluster-assembled growth regimes. For compact U-NLs, we report high mass density (∼8.35 g/cm3) and enhanced and tunable mechanical behavior, reaching maximum values of hardness and yield strength of up to 9.3 and 3.6 GPa, respectively. In addition, we show up to 3.6% homogeneous elastoplastic deformation in compression as a result of SB blocking by the Al-rich sublayers. On the other hand, nanogranular U-NLs exhibit slightly lower yield strength (3.4 GPa) in combination with enhanced elastoplastic deformation (∼6%) followed by the formation of superficial SBs, which are not percolative even at deformations exceeding 15%, as a result of the larger free volume content within the cluster-assembled structure and the presence of crystal/glass nanointerfaces, enabling to accommodate SB events. Overall, we show how PLD enables the synthesis of crystal/glass U-NLs with ultimate control of local heterogeneities down to the atomic scale, providing new nanoengineered strategies capable of deep control of the deformation behavior, surpassing traditional trade-off between strength and ductility. Our approach can be extended to other combinations of metallic materials with clear interest for industrial applications such as structural coatings and microelectronics (MEMS and NEMS).

Jet Electroforming of High-Aspect-Ratio Microcomponents by Periodically Lifting a Necked-Entrance Through-Mask.

High-aspect-ratio micro- and mesoscale metallic components (HAR-MMMCs) can play some unique roles in quite a few application fields, but their cost-efficient fabrication is significantly difficult to accomplish. To address this issue, this study proposes a necked-entrance through-mask (NTM) periodically lifting electroforming technology with an impinging jet electrolyte supply. The effects of the size of the necked entrance of the through-mask and the jet speed of the electrolyte on electrodeposition behaviors, including the thickness distribution of the growing top surface, deposition defect formation, geometrical accuracy, and electrodeposition rate, are investigated numerically and experimentally. Ensuring an appropriate size of the necked entrance can effectively improve the uniformity of deposition thickness, while higher electrolyte flow velocities help enhance the density of the components under higher current densities, reducing the formation of deposition defects. It was shown that several precision HAR-MMMCs with an AR of 3.65 and a surface roughness (Ra) of down to 36 nm can be achieved simultaneously with a relatively high deposition rate of 3.6 μm/min and thickness variation as low as 1.4%. Due to the high current density and excellent mass transfer effects in the electroforming conditions, the successful electroforming of components with a Vickers microhardness of up to 520.5 HV was achieved. Mesoscale precision columns with circular and Y-shaped cross-sections were fabricated by using this modified through-mask movable electroforming process. The proposed NTM periodic lifting electroforming method is promisingly advantageous in fabricating precision HAR-MMMCs cost-efficiently.

An analysis of parameters affecting ampacity in aircraft bipolar MVDC power cables via coupled electrical, thermal, and computational fluid dynamic modelling

AbstractThe next generation of aircraft, including more electric aircraft and all‐electric aircraft, require electric power systems with high power density and low system mass specifications. Increasing the voltage of the system to the range of a few kV, medium voltage (MV), is a reasonable approach to achieving high‐power‐density and low‐system‐mass EPSs for aircraft applications. Higher voltages, however, pose many challenges for aviation MV power cables such as arcs and arc tracking, partial discharges (PDs), and thermal management. In this regard, thermal management is more challenging since heat transfer by convection is greatly reduced at wide‐body aircraft's cruising altitudes due to the reduced air pressure. In this paper, a finite element method (FEM) model is developed in COMSOL Multiphysics for an aircraft bipolar MVDC (±5 kV) power cable. Using the model, the maximum permissible cable current at a low pressure of 18.8 kPa (at an altitude of 12.2 km from sea level, the usual cruising altitude for wide‐body aircraft) is calculated. Also, an analytical model is developed based on analytical and proven empirical correlations governing conductive, radiative, and convective heat transfers at the steady state to estimate the ampacity of the bipolar cable system at reduced pressure. It was shown that the proposed analytical model can be used for atmospheric pressure and systems with a larger number of poles, expanding its range of applications. The results of the FEM and analytical models correlate at wide ranges of parameters such as ambient temperature, duct size, distance between the positive and negative pole cables, and the overall diameter of the cables. The influence of horizontal and vertical arrangement of poles is included in the analytical model. The results of this study can be used to design bipolar MVDC power cable systems for the envisaged wide‐body AEA.

The effect of temperature on the co-combustion of hydrochar and NH3 using the ReaxFF method

The utilization of NH3, a carbon-free hydrogen carrier, can be optimized through its co-combustion with solids. However, prior studies have primarily focused on coal as the solid fuel, which entails its consumption. Considering that hydrochar possesses abundant oxygen-containing functional groups, as well as high mass and energy density, it presents itself as a promising alternative solid fuel to coal, thereby decreasing dependence on fossil fuels. Therefore, this study investigates the co-combustion of different proportions of hydrochar, NH3, and O2. Molecular dynamic simulations using the ReaxFF MD method were conducted to investigate the impact of temperature on combustion by analyzing product distribution, evolution of bonds, and gas characteristic curves. Additionally, N migration was examined to elucidate the processes leading to the generation of N2 and NOx from NH3. The results showed that temperature facilitated the progression of combustion as the total number of molecules increased (from 2614 at 2000 K to 3137 at 2500 K) and variety of products expanded (from 48 at 2000 K to 69 at 2500 K) with increasing temperature. With increasing temperature, the descent rate of NH3 and oxygen accelerated, whereas the quantities of H2 and H2O increased. Furthermore, during combustion, hydrochar underwent three stages: initial coke formation, subsequent tar generation, and organic gas production. Second, during N migration, hydrochar directly or indirectly participated in the formation of N2. In this process, hydrochar indirectly contributed to the formation of NH and NH2 intermediates, leading to the formation of N2. In contrast, the majority of NO was formed through the direct decomposition of hydrochar. Finally, because of the limited quantity of generated NO2, N existed primarily in the form of N2 and NO. These findings provide theoretical guidance for the combustion of NH3 using hydrochar.

Cross-sectional geometry effect on bending strength of gold micro-cantilever with trapezoidal cross-section

Gold is a promising material for movable components in MEMS devices by the high mass density, which allows reduction of the Brownian noise. Mechanical properties of metallic materials are known to be affected by the sample size effect. When bending test is utilized, the sample geometry effect is another factor. In this study, effects of the shape of the cross-section, or the cross-sectional geometry effect, are evaluated using micro-cantilevers with a trapezoidal cross-section. The yield stresses are ranged from 112 MPa to 185 MPa in micro-cantilevers composed of single crystalline gold, and the yield stresses varied from 372 MPa to 489 MPa in polycrystalline gold micro-cantilevers. The yield stress is found to be higher in the micro-cantilever having a smaller ratio of the top width over the bottom width, which demonstrates the cross-sectional geometry effect. Also, the cross-sectional geometry effect is more significant in the polycrystalline micro-cantilevers.

Light competition drives species replacement during secondary tropical forest succession

Light competition is thought to drive successional shifts in species dominance in closed vegetations, but few studies have assessed this for species-rich and vertically structured tropical forests. We analyzed how light competition drives species replacement during succession, and how cross-species variation in light competition strategies is determined by underlying species traits. To do so, we used chronosequence approach in which we compared 14 Mexican tropical secondary rainforest stands that differ in age (8–32 year-old). For each tree, height and stem diameter were monitored for 2 years to calculate relative biomass growth rate (RGR, the aboveground biomass gain per unit aboveground tree biomass per year). For each stand, 3D light profiles were measured to estimate individuals’ light interception to calculate light interception efficiency (LIE, intercepted light per unit biomass per year) and light use efficiency (LUE, biomass growth per intercepted light). Throughout succession, species with higher RGR attained higher changes in species dominance and thus increased their dominance over time. Both light competition strategies (LIE and LUE) increased RGR. In early succession, a high LIE and its associated traits (large crown leaf mass and low wood density) are more important for RGR. During succession, forest structure builds up, leading to lower understory light levels. In later succession, a high LUE and its associated traits (high wood density and leaf mass per area) become more important for RGR. Therefore, successional changes in relative importance of light competition strategies drive shifts in species dominance during tropical rainforest succession.

Imaging Patterns of Breast Cancer in Women of Reproductive Age

Background: While breast cancer is less common in younger women compared to older age groups, it can still occur, necessitating careful evaluation of imaging findings. Imaging patterns of breast cancer in women of reproductive age can vary, presenting unique challenges in diagnosis and management. This study aimed to assess the imaging patterns of breast cancer in women of reproductive age. Methods: This prospective observational study was conducted in the Department of Radiology and Imaging Uttara Adhunik Medical College &amp; Hospital and Dhaka Medical College Hospital, Dhaka, Bangladesh from January 2019 to December 2023. In this study, 67 women of reproductive age who had been diagnosed with breast carcinoma and had undergone preoperative breast imaging were enrolled purposively. Data analysis was conducted using MS Office tools. Results: Mammographic findings: 42% had heterogeneously dense breasts, 30% scattered composition; and 87% had high mass density. Irregular mass shape: 43% (mammography), 69% (ultrasonography). In total 85% of cases were pleomorphic. Ultrasonography evaluation: 69% had a single US background. Echogenicity distribution: 61% hypoechoic among patients. MRI findings: 37% mild, 31% moderate, 22% minimal. Besides, 87% showed heterogeneous mass enhancement; 63% had segmental non-mass distribution. Conclusion: In breast cancer cases, imaging findings often include masses exhibiting suspicious features such as irregular shape and spiculated margins on mammograms, and irregular shape with angular margins on ultrasound. MRI features commonly involve masses with irregular shapes and heterogeneous enhancement.

Developing strong-yet-ductile light-weight medium-entropy alloy via the unusual oxide doping effect

High or medium entropy alloys (M/HEAs) possess outstanding mechanical and thermal properties, but their high mass density severely restricts their practical applications. In this study, we designed a novel light-weight MEA based on the TiAlCrNb-x(ZrO2) system. These ZrO2 particles doped can completely dissolve in the β-phase structure of the TiAlCrNb MEA, which contrasts with conventional ceramic strengthening introduced through powder metallurgy. Consequently, it promotes the formation of Ti3Al nanoparticles and simultaneously substantially reduces grain size, thereby achieving a remarkable strength-ductility combination with a high specific yield strength of 225/250 MPa/(g·cm−3) while maintaining an excellent tensile ductility of 19.5/10.1% in the newly designed TiAlCrNb-(1.2/1.5)(ZrO2) MEAs. This performance outperforms most other light-weight M/HEAs. Strengthened mechanisms analysis indicates that the strength increment is attributed to grain-refinement-induced Hall-Petch strengthening and solid-solution strengthening from the dissolved oxygen. The results offer insight into the innovative design of ultrastrong and ductile light-weight MEAs for advanced structural applications.

Elastic fields generated by multiple small inclusions with high mass density at nearly resonant frequencies

We derive the elastic field generated by multiple small-scaled inclusions distributed in a bounded set of R3. These inclusions are modelled with moderate values of the Lamé coefficients while they have a large relative mass density. These properties allow them to enjoy sequences of resonant frequencies that can be computed via the eigenvalues of the volume integral operator having the Navier fundamental matrix as a kernel, i.e., the Navier volume operator. The dominant field, i.e., the Foldy-Lax field, models the multiple interactions between the inclusions with scattering coefficients that are inversely proportional to the difference between the used incident frequency and the already mentioned resonances. We show, in particular, that to reconstruct remotely the scattered field generated after N interactions between the inclusions, one needs to use an incident frequency appropriately close to the proper resonance of the inclusions. We provide an explicit link between the order N of interactions and the distance from the incident frequency to the resonance. Finally, if the cluster of the inclusions is densely distributed in a given bounded domain, then the expression of the induced dominant field suggests that the equivalent homogenized mass density can change sign depending if the used incident frequencies is smaller or larger than a certain threshold (which is explicitly given in terms of the resonant frequencies of the inclusions).

NSCs from groups to clusters: A catalogue of dwarf galaxies in the Shapley Supercluster and the role of environment in galaxy nucleation

Abstract Nuclear star clusters (NSCs) are dense star clusters located at the centre of galaxies spanning a wide range of masses and morphologies. Analysing NSC occupation statistics in different environments provides an invaluable window into investigating early conditions of high-density star formation and mass assembly in clusters and group galaxies. We use HST/ACS deep imaging to obtain a catalogue of dwarf galaxies in two galaxy clusters in the Shapley Supercluster: the central cluster Abell 3558 and the northern Abell 1736a. The Shapley region is an ideal laboratory to study nucleation as it stands as the highest mass concentration in the nearby Universe. We investigate the NSC occurrence in quiescent dwarf galaxies as faint as MI = −10 mag and compare it with all other environments where nucleation data is available. We use galaxy cluster/group halo mass as a proxy for the environment and employ a Bayesian logistic regression framework to model the nucleation fraction (fn) as a function of galaxy luminosity and environment. We find a notably high fn in Abell 3558: at MI ≈ −13.1 mag, half the galaxies in the cluster host NSCs. This is higher than in the Virgo and Fornax clusters but comparable to the Coma Cluster. On the other hand, the fn in Abell 1736a is relatively lower, comparable to groups in the Local Volume. We find that the probability of nucleation varies with galaxy luminosity remarkably similarly in galaxy clusters. These results reinforce previous findings of the important role of the environment in NSC formation/growth.