Evolution Of Clusters Research Articles

Structural stability analysis of spherical bubble clusters in acoustic cavitation fields

The upwelling growth and evolution of spherical bubble clusters appearing at one-quarter wavelength from the water surface in ultrasonic cavitation fields at frequencies of 28 kHz and 40 kHz are studied by high-speed photography. Due to the interactions among bubbles, the stable bubble aggregation occurs throughout the rise of the bubble cluster, whose vertical pressure difference leads to a more significant spreading in the upper part of the cluster in the standing-wave field. At 28 kHz, the rising speed is about 0.6 m/s, controlled by the primary acoustic field. After a violent collapse of the bubble clusters, the aggregating structure begins to hover near the water surface. The size and stability of the structure are affected by the frequency and pressure of the primary acoustic field. If two clusters are close to each other, the clusters deviate from the spherical shape, even trailing off, and eventually merge into a single bubble cluster. By considering the influence of water-air boundary, based on the mirror principle, a spherical bubble cluster model is developed to explore the structure stability of the clusters, and the modified dynamics equations are obtained. The effects of driving acoustic pressure amplitude, bubble number density, water depth, and bubble equilibrium radius on the optimal stable radius of the spherical bubble cluster are numerically analyzed by using the equivalent potentials at 28 kHz and 40 kHz. The results show that the optimal stabilizing radius of spherical bubble cluster is in a range of 1–2 mm, and it tends to decrease slightly with the increase of the driving acoustic pressure and bubble number density. It is worth noting that the nonlinearity is enhanced by increasing acoustic pressure, which may promote the stability of the cluster structure. The smaller the unstable equilibrium radius, the easier it is to grow, and the stable size at 40 kHz is slightly smaller than that at 28 kHz. Generally, spherical clusters first appear in a high-pressure region and then move to a low-pressure region. If the acoustic pressure drops below a certain critical value, bubble clusters disappear. The theoretical analysis is in good agreement with the experimental observation. The analysis of the growth and structural stability of spherical bubble cluster is helpful in understanding the behavioral modulation of bubbles.

Evolution of clusters of turbulent reattachment due to shear layer instability in flow past a circular cylinder

We perform large eddy simulations of flow past a circular cylinder for the Reynolds number (Re) range, 2×103≤Re≤4×105, spanning subcritical, critical, and supercritical regimes. We investigate the spanwise coherence of the flow in the critical and supercritical regimes using complex networks. In these regimes, the separated flow reattaches to the surface in a turbulent state due to the turbulence generated by the shear layer instability. In the early critical regime, the turbulent reattachment does not occur simultaneously at all span locations. It occurs incoherently along the span in clusters. We treat strong surface pressure fluctuations due to the shear layer instability as extreme events and construct time-varying spatial proximity networks where links are based on synchronization between events. This analysis unravels the underlying complex spatiotemporal dynamics by enabling the estimation of characteristics of clusters of turbulent reattachment via the concept of connected components. In the critical regime, the number and size of the clusters increase with the increase in Re. At higher Re in the supercritical regime, they coalesce to form bigger clusters, resulting in increase in spanwise coherence of turbulent reattachment. We find that the size and number of clusters govern the variation of the time-averaged coefficient of drag (C¯D) in the critical and supercritical regimes. C¯D exhibits power-law distribution with the largest cluster size (C¯D∝S¯CL−25) and the most probable cluster size [C¯D∝E(SC)−25].

Analysis of icosahedral structure in rapidly solidified Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy under high pressure

Compared with traditional glass, metallic glass (MG) has excellent properties, such as high strength, high hardness, high fracture toughness, good soft magnetic properties and corrosion resistance due to its unique structure. Such properties enable it to be used in optics, electronics, construction and other fields, making it a highly promising new material with great application potential. As the properties of amorphous alloys are closely linked with their local structures, microstructure characteristics have always been a research focus in the amorphous field. Previous studies show that the onset temperature of heredity and the hereditary fraction of characteristic clusters can be used to effectively evaluate the glass-forming ability. In order to obtain the relationship between the microstructure characteristic and cluster evolution of amorphous alloy, and reveal the formation of glass, the glass transition processes of the Pd<sub>82</sub>Si<sub>18</sub> alloy under different pressure conditions are simulated by using the molecular dynamics method, and the heredity and evolution of the Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy are analyzed by using the cluster-type index method and the reverse tracking method. The simulation results show that the glass transition temperature of the Pd<sub>82</sub>Si<sub>18</sub> alloy can be increased when the pressure is higher, and a large number of icosahedra are formed in the solidified alloy when the pressure is sufficiently high. Icosahedron is a kind of structure that widely exists in amorphous materials and has been studied for quite a long time. In this work, a detailed comparative analysis of two icosahedra is conducted and the heritability of clusters with different chemical compositions under high pressure is studied. The results show that it is easier for icosahedra with central atom Pd and those with central atom Si to form a medium-range order in the Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy. An increase in pressure conduces to the increase of both onset temperature of heredity and hereditary fraction. Combined with the results of cluster heredity analysis at 0 GPa, the Si-centered clusters have stronger heritability than Pd-centered clusters, thus the former ones have a greater influence on the glass-forming ability. These findings are of significance in understanding the relationship between microstructure evolution and glass formation, and also providing certain guidance for designing amorphous alloys.

Analysis of icosahedral structure in rapidly solidified Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy under high pressure

Compared with traditional glass, metallic glass (MG) has excellent properties, such as high strength, high hardness, high fracture toughness, good soft magnetic properties and corrosion resistance due to its unique structure. Such properties enable it to be used in optics, electronics, construction and other fields, making it a highly promising new material with great application potential. As the properties of amorphous alloys are closely linked with their local structures, microstructure characteristics have always been a research focus in the amorphous field. Previous studies show that the onset temperature of heredity and hereditary fraction of characteristic clusters can be used to effectively evaluate the ability of an amorphous alloy to form glass. In order to obtain the relationship between the microstructure characteristic and cluster evolution of amorphous alloy, and reveal the formation of glass, the glass transition processes of the Pd<sub>82</sub>Si<sub>18</sub> alloy under different pressure conditions are simulated by using the molecular dynamics method, and the heredity and evolution of the Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy are analyzed by using the cluster-type index method and the reverse tracking method. The simulation results show that the glass transition temperature of the Pd<sub>82</sub>Si<sub>18</sub> alloy can be increased when the pressure is higher, and a large number of icosahedra are formed in the solidified alloy when the pressure is sufficiently high. Icosahedron is a kind of structure that widely exists in amorphous materials and has been studied for quite a long time. In this work, a detailed comparative analysis on two icosahedra is conducted and the heritability of clusters with different chemical compositions under high pressure is studied. The results show that it is easier for icosahedra with central atom Pd and those with central atom Si to form a medium-range order in the Pd<sub>82</sub>Si<sub>18</sub> amorphous alloy. An increase in pressure conduces to the increasing of both onset temperature of heredity and hereditary fraction. Comparing with the results of cluster heredity analysis under 0 GPa, the Si-centered clusters have stronger heritability than Pd-centered clusters, thus the former ones have a greater influence on the ability to form glass. These findings are of significance in understanding the relationship between microstructure evolution and glass formation,and also providing certain guidance for designing amorphous alloys.

Bond strength of substrate with repair material for masonry structures

Masonry infrastructure repair is a daunting challenge. The short intervention and limited resources have led to the loss of novel rendering and finishing materials. In the present study, the bibliometric analysis is conducted for period 2003 to 2022. Co-cited reference analysis, keywords, cluster, and temporal evolution were used for analysis using Citespace software. Additionally, summary of suitable content showed that major challenges in this field are disparities in the properties of old mortar and new materials and the lack of documents to understand nature and methodology of construction. Based on the analysis and content review, a suggestive technique is proposed inculcating four aspects: Finite element analysis, preparing numerical models, improvised techniques for bonding mechanisms and understanding mechanical attributes.

Silver-Rich Clusters Reveal the Initial Size of Nanoscale Network during Dealloying Via Kinetic Monte Carlo Simulation

As residues of the master alloy that survived corrosion, the silver-rich clusters of nanoporous gold (NPG) fabricated by dealloying affect the functional properties of the material. Also, they are representative of the initial nanoscale network established at the beginning of dealloying. The evolution of silver-rich clusters during dealloying at different potentials is investigated via kinetic Monte Carlo simulations [1]. Our simulations show that the dealloying consists of two characteristic processes: (i) the primary process produces an initial three-dimensional bicontinuous network with silver-rich clusters embedded in the ligaments and pure gold covered on ligaments' surface. See Fig.1(a). (ii) the secondary process coarsens the ligaments and further dissolves silver from the ligaments. See Fig.1(b). The size of silver-rich clusters, L Ag, scales with that of ligaments, L lig, during primary dealloying for all studied potentials (Fig.1(c)). Both sizes decrease with increasing dealloying potential. The trends in size and potential are consistent with a Gibbs-Thompson-type relation (dash-dotted line in Fig.1(c)). Yet, the size of silver clusters remains invariant when the ligament size increases during secondary dealloying. Our simulations reveal that the survived clusters provided a way to measure the initial ligament size.Fig.1. Renderings of slicing the NPG structure at different dealloying time (a-b) and the size evolution during primary dealloying (c) (Ref.[1]): (a) the primary dealloying establishes the initial 3D nanoscale network, (b) the secondary dealloying dissolves Ag clusters and coarsens ligaments, (c) inverse of Ag cluster size, L Ag and of ligament size, L lig, during primary dealloying as a function of dealloying potential, Φ.Reference:[1] Y. Li, B.-N. D. Ngô, J. Markmann, J. Weissmüller. Evolution of length scales and of chemical heterogeneity during primary and secondary dealloying, Acta Materialia, (2021) 117424. Figure 1

Natural aging and vacancy trapping in Al-6xxx

Undesirable natural aging (NA) in Al-6xxx delays subsequent artificial aging (AA) but the size, composition, and evolution of clustering are challenging to measure. Here, atomistic details of early-stage clustering in Al–1%Mg–0.6%Si during NA are studied computationally using a chemically-accurate neural-network potential. Feasible growth paths for the preferred beta '' precipitates identify: dominant clusters differing from beta '' motifs; spontaneous vacancy-interstitial formation creating 14–18 solute atom beta ''-like motifs; and lower-energy clusters requiring chemical re-arrangement to form beta '' nuclei. Quasi-on-lattice kinetic Monte Carlo simulations reveal that 8–14 solute atom clusters form within 1000 s but that growth slows considerably due to vacancy trapping inside clusters, with trapping energies of 0.3-0.5 eV. These findings rationalize why cluster growth and alloy hardness saturate during NA, confirm the concept of “vacancy prisons”, and suggest why clusters must be dissolved during AA before formation of beta ''. This atomistic understanding of NA may enable design of strategies to mitigate negative effects of NA.Graphical abstractEnergy and RMS vacancy displacement vs simulation time for three different kMC simulations of Al matrix containing Mg (green) and Si atoms(orange), and 1 vacancy (pink). Geometries extracted from the third trajectory at four different times show solute clustering and vacancy trapping.

Study of natural aging behavior of Al-0.4Mg-1.0Si alloy with the addition of Sn at different solution heat treatment temperatures

In this paper, the combined effect of Sn addition and solution treatment temperature on natural aging (NA) hardness behavior and microstructure of Al-0.4Mg-1.0Si alloy were investigated by hardness test, scanning electron microscope (SEM) and scanning transmission electron microscope (STEM). The evolutions of clusters characterized by three-dimensional atom probe (3DAP) during initials stages of NA are also investigated based on the slow in formation of clusters due to Sn addition. The results shown that a Sn-rich particles with round shape retained in Al matrix after quenching treatment when the added Sn content exceeds it limit solubility, which will reduce the Mg content of the designed alloy. The suppression of NA can be enhanced with the increase in the adding Sn content and solution treatment temperature, which is strongly related to the delay of the segregation of Mg and Si to form clusters due to more trapping vacancies by Sn atoms. The addition of Sn also revealed that the segregation of Si during NA is earlier than that of Mg atoms. The Si-rich clusters are formed preferentially during initial stage of NA, and Mg–Si co-clusters are formed after long period of NA. The Mg/Si ratio and average size of Sn-containing clusters in the 0.04%Sn and 0.1%Sn alloy are obviously higher than that of Sn-free clusters regardless of the 1 day NA or 14 days NA as more Mg atoms are dragged into Sn-containing clusters due to strong interaction between Sn and Mg atoms.

On the Identification of N-rich Metal-poor Field Stars with Future Chinese Space Station Telescope

During the long term evolution of globular clusters (GCs), some member stars are lost to the field. The recently found nitrogen-rich (N-rich) metal-poor field stars are promising candidates of these GC escapees, since N enhancement is the fingerprint of chemically enhanced populations in GCs. In this work, we discuss the possibility of identifying N-rich metal-poor field stars with the upcoming Chinese Space Station Telescope (CSST). We focus on the main survey camera with NUV, u, g, r, i, z, y filters and slitless spectrograph with a resolution about 200. The combination of UV sensitive equipment and prominent N-related molecular lines in the UV band bodes well for the identification: the color–color diagram of (u − g) versus (g − r) is capable of separating N-rich field stars from normal halo stars, if metallicity can be estimated without using the information on u-band photometry. Besides, the synthetic spectra show that a signal-to-noise ratio of 10 is sufficient to identify N-rich field stars. In the near future, a large sample of N-rich field stars found by CSST, combined with state-of-the-art N-body simulations will be crucial to deciphering GC-Galaxy co-evolution.

Research on Grading and Evolution of International Trade Development Quality of City Clusters Based on Logit-ISM Modeling

Abstract In order to further accelerate the realization of high-quality development of international trade and enhance the discourse power in international trade activities, this paper explores the grading and evolution of the quality of international trade development of city clusters. After analyzing the DEA static model and DEA-Malmquist dynamic evaluation model, combined with the entropy value method, the entropy value-DEA model is constructed to measure the comprehensive evaluation of the quality of international trade development of the city cluster, and the results are comprehensively analyzed. In addition, combined with the Logit-ISM model to analyze the factors affecting the development quality of international trade of city cluster and explore the grading and evolution of the development quality of international trade of city cluster from two perspectives of global statistics and global spatial trend. The results show that the fluctuation of the trade structure score is smaller than the trade scale, with an average growth rate of 0.165, and the trade competitiveness score basically stays in a state of growth except for 2008 and 2009, with an average annual growth rate of 0.972. The urban agglomerations in the eastern region account for a total of 0.38 of the city agglomerations in the city agglomerations synthesis, and the number of prefectural-level cities included is 106, which accounts for a total of 0.52 of the number of prefectural-level cities included in the city agglomerations. The quality of international trade development in city clusters in the eastern and northeastern regions stands out as the most significant. Based on the research in this paper, we advocate for the balanced development of the quality rating and evolution of each city cluster in international trade development.

Clustering effects and evolution of the global major 10-year government bond market structure: A network perspective

This paper takes the 10-year government bond yields of 40 important economies in the world as the research object, aiming to establish a global major government bond market network based on the graph approach and construct an evaluation system to understand the clustering effects of different economies in some important global financial events and the evolution of market structure. Based on the rich information provided by the minimum spanning tree and planar maximally filtered graph, our empirical research results indicate that economies in the government bond market network exhibit clustering effects due to geographical proximity and similar yield levels. The GIIPS economies in Europe formed a core cluster during the European debt crisis period and the initial stage of the COVID-19 outbreak and formed clustering effects with other high-yield economies. In the initial stage of Sino-US trade friction, the market formed the phenomenon of European-American clusters and Asia-Pacific clusters. We also observed that in the complete research interval from 2010 to 2021, Germany and Netherlands had the strongest centrality, while the two largest economies in the world, the United States and China, also maintained close connections with them in the network structure. Through the interdisciplinary graph network approach, we hope to provide an effective perspective to observe and monitor the operation of the global government bond market.

The banking phenomenon of North Carolina: from origins to the present

Although not one of the largest states and ranking just ninth in the USA in terms of population, North Carolina has been a major banking hub for several decades, second only to New York. This article focuses on the early foundations of this success and the later evolution of the North Carolina banking cluster, tracing its development through statistics from the late 1970s to the present. It is shown that an important advantage in the 19th century was the lifting of the ban on bank branching, which was not typical in the USA at that time. As a result, by the early 1980s, when the gradual liberalization of the national banking system and the abolition of territorial restrictions began, quite large banking corporations already existed in North Carolina, ready for further business expansion and operations in other parts of the country. Following a long series of mergers and acquisitions in the 1980s, 1990s, and 2000s, the state's leading bank holding companies (Bank of America Corporation and Wachovia Corporation) became among the largest and most powerful financial groups in the USA. However, it soon became clear that there was another side to this extremely rapid growth: due to its deep involvement in subprime mortgages, Wachovia collapsed during the 2008 crisis. Nevertheless, Bank of America and several other large companies overcame the crisis, ensuring North Carolina maintained a strong position in the industry. To date, North Carolina's phenomenal rise remains the most significant spatial change in the US banking system since its liberalization began more than 40 years ago.

Topological structures and syntenic conservation in sea anemone genomes

There is currently little information about the evolution of gene clusters, genome architectures and karyotypes in early branching animals. Slowly evolving anthozoan cnidarians can be particularly informative about the evolution of these genome features. Here we report chromosome-level genome assemblies of two related anthozoans, the sea anemones Nematostella vectensis and Scolanthus callimorphus. We find a robust set of 15 chromosomes with a clear one-to-one correspondence between the two species. Both genomes show chromosomal conservation, allowing us to reconstruct ancestral cnidarian and metazoan chromosomal blocks, consisting of at least 19 and 16 ancestral linkage groups, respectively. We show that, in contrast to Bilateria, the Hox and NK clusters of investigated cnidarians are largely disintegrated, despite the presence of staggered hox/gbx expression in Nematostella. This loss of microsynteny conservation may be facilitated by shorter distances between cis-regulatory sequences and their cognate transcriptional start sites. We find no clear evidence for topologically associated domains, suggesting fundamental differences in long-range gene regulation compared to vertebrates. These data suggest that large sets of ancestral metazoan genes have been retained in ancestral linkage groups of some extant lineages; yet, higher order gene regulation with associated 3D architecture may have evolved only after the cnidarian-bilaterian split.

Phylogeny and molecular evolution of the first local monkeypox virus cluster in Guangdong Province, China

The first local mpox outbreak in Guangdong Province, China occurred in June 2023. However, epidemiological data have failed to quickly identify the source and transmission of the outbreak. Here, phylogeny and molecular evolution of 10 monkeypox virus (MPXV) genome sequences from the Guangdong outbreak were characterized, revealing local silent transmissions that may have occurred in Guangdong whose mpox outbreaks suggested a molecular epidemiological correlation with Portugal and several regions of China during the same period. The lineage IIb C.1, which includes all 10 MPXV from Guangdong, shows consistent temporal continuity in both phylogenetic characteristics and unique molecular evolutionary mutation spectrum, reflected in the continuous increase of single nucleotide polymorphisms (SNPs) and shared mutations over time. Compared with the Japan MPXV, the Guangdong MPXV showed higher genomic nucleotide differences and separated 14 shared mutations from the B.1 lineage, comprising 6 non-synonymous mutations in genes linked to host regulation, virus infection, and virus life cycle. The unique mutation spectrum with temporal continuity in IIb C.1, related to apolipoprotein B mRNA-editing catalytic polypeptide-like 3, promotes rapid viral evolution and diversification. The findings contribute to understanding the ongoing mpox outbreak in China and offer insights for developing joint prevention and control strategies.

Stellar populations in STARFORGE: the origin and evolution of star clusters and associations

ABSTRACT Most stars form in highly clustered environments within molecular clouds, but eventually disperse into the distributed stellar field population. Exactly how the stellar distribution evolves from the embedded stage into gas-free associations and (bound) clusters is poorly understood. We investigate the long-term evolution of stars formed in the starforge simulation suite – a set of radiation-magnetohydrodynamic simulations of star-forming turbulent clouds that include all key stellar feedback processes inherent to star formation. We use nbody6++gpu to follow the evolution of the young stellar systems after gas removal. We use HDBSCAN to define stellar groups and analyse the stellar kinematics to identify the true bound star clusters. The conditions modeled by the simulations, i.e. global cloud surface densities below 0.15 g cm−2, star formation efficiencies below 15 per cent, and gas expulsion time-scales shorter than a free fall time, primarily produce expanding stellar associations and small clusters. The largest star clusters, which have ∼1000 bound members, form in the densest and lowest velocity dispersion clouds, representing ∼32 and 39 per cent of the stars in the simulations, respectively. The cloud’s early dynamical state plays a significant role in setting the classical star formation efficiency versus bound fraction relation. All stellar groups follow a narrow mass-velocity dispersion power-law relation at 10 Myr with a power-law index of 0.21. This correlation result in a distinct mass–size relationship for bound clusters. We also provide valuable constraints on the gas dispersal time-scale during the star formation process and analyse the implications for the formation of bound systems.

Globular clusters contribute to the nuclear star clusters and galaxy centre γ-ray excess, moderated by galaxy assembly history

ABSTRACT Two unresolved questions at galaxy centres, namely the formation of the nuclear star cluster (NSC) and the origin of the γ-ray excess in the Milky Way (MW) and Andromeda (M31), are both related to the formation and evolution of globular clusters (GCs). They migrate towards the galaxy centre due to dynamical friction, and get tidally disrupted to release the stellar mass content including millisecond pulsars (MSPs), which contribute to the NSC and γ-ray excess. In this study, we propose a semi-analytical model of GC formation and evolution that utilizes the Illustris cosmological simulation to accurately capture the formation epochs of GCs and simulate their subsequent evolution. Our analysis confirms that our GC properties at z = 0 are consistent with observations, and our model naturally explains the formation of a massive NSC in a galaxy similar to the MW and M31. We also find a remarkable similarity in our model prediction with the γ-ray excess signal in the MW. However, our predictions fall short by approximately an order of magnitude in M31, indicating distinct origins for the two γ-ray excesses. Meanwhile, we utilize the catalogue of Illustris haloes to investigate the influence of galaxy assembly history. We find that the earlier a galaxy is assembled, the heavier and spatially more concentrated its GC system behaves at z = 0. This results in a larger NSC mass and brighter γ-ray emission from deposited MSPs.

Bibliometric and visual analysis of intraoperative hypotension from 2004 to 2022.

Intraoperative hypotension (IOH) is a common complication occurring in surgical practice. This study aims to comprehensively review the collaboration and impact of countries, institutions, authors, journals, keywords, and critical papers on intraoperative hypotension from the perspective of bibliometric, and to evaluate the evolution of knowledge structure clustering and identify research hotspots and emerging topics. Articles and reviews related to IOH published from 2004 to 2022 were retrieved from the Web of Science Core Collection. Bibliometric analyses and visualization were conducted on Excel, CiteSpace, VOSviewer, and Bibliometrix (R-Tool of R-Studio). A total of 1,784 articles and reviews were included from 2004 to 2022. The number of articles on IOH gradually increased in the past few years, and peaked in 2021. These publications were chiefly from 1,938 institutions in 40 countries, led by America and China in publications. Sessler Daniel I published the most papers and enjoyed the highest number of citations. Analysis of the journals with the most outputs showed that most journals concentrated on perioperative medicine and clinical anesthesiology. Delirium, acute kidney injury and vasoconstrictor agents are the current and developing research hotspots. The keywords "Acute kidney injury", "postoperative complication", "machine learning", "risk factors" and "hemodynamic instability" may also become new trends and focuses of the near future research. This study uses bibliometrics and visualization methods to comprehensively review the research on intraoperative hypotension, which is helpful for scholars to better understand the dynamic evolution of IOH and provide directions for future research.

The dominant mechanism(s) for populating the outskirts of star clusters with neutron star binaries

ABSTRACT It has been argued that heavy binaries composed of neutron stars (NSs) and millisecond pulsars (MSPs) can end up in the outskirts of star clusters via an interaction with a massive black hole (BH) binary expelling them from the core. We argue here, however, that this mechanism will rarely account for such observed objects. Only for primary masses ≲100 M⊙ and a narrow range of orbital separations should a BH–BH binary be both dynamically hard and produce a sufficiently low recoil velocity to retain the NS binary in the cluster. Hence, BH binaries are in general likely to eject NSs from clusters. We explore several alternative mechanisms that would cause NS/MSP binaries to be observed in the outskirts of their host clusters after a Hubble time. The most likely mechanism is a three-body interaction involving the NS/MSP binary and a normal star. We compare to Monte Carlo simulations of cluster evolution for the globular clusters NGC 6752 and 47 Tuc, and show that the models not only confirm that normal three-body interactions involving all stellar-mass objects are the dominant mechanism for putting NS/MSP binaries into the cluster outskirts, but also reproduce the observed NS/MSP binary radial distributions without needing to invoke the presence of a massive BH binary. Higher central densities and an episode of core collapse can broaden the radial distributions of NSs/MSPs and NS/MSP binaries due to three-body interactions, making these clusters more likely to host NSs in the cluster outskirts.

Discovery of a series of silicon-based ferrimagnets in CrMnSin (n = 4-20) clusters.

Herein, the structural evolution, electronic and magnetic properties of silicon clusters with two different dopants, CrMnSin (n = 4-20) clusters were investigated at density functional theory (DFT) level. Small-sized CrMnSin (n = 4-9) clusters tend to adopt bipyramid-based geometries, while clusters with sizes n = 10 and 11 prefer to opening cage-like structures. For sizes n = 12 to 14, the half-encapsulated structures gradually transform into closed-cage Cr@Sin structures, with the Mn atom exposed outside. Starting from size 15, both the Cr and Mn atoms are completely encapsulated by silicon atoms. Meanwhile, the Cr and Mn atoms in smaller-sized CrMnSin (n = 4-7) clusters tend to be separated, while they prefer to stay together for larger sizes. Cr atom always acts as electron donor, but not for Mn atom. From the average binding energies, one can conclude that it is easier to form larger size clusters. Smaller and larger sized CrMnSin (n = 4-9 and 19-20) clusters prefer to exhibit ferromagnetic Cr-Mn coupling, while sizes n = 10-18 always exhibit ferrimagnetic state. To our knowledge, the CrMnSin clusters is the first kind of neutral transition-metal doped semiconductor clusters that show ferrimagnetic state within a wide size range.

Structural description of temperature evolution of polar clusters in PLZT relaxor ceramics

ABSTRACT This letter quantifies the phases by Rietveld refinement of perovskite relaxor ferroelectric ceramics of lanthanum-modified lead titanate zirconate (PLZT 9/65/35) as a function of temperature. The refinement results show the relative limit of phases between the polar electrical percolation and their vanishing as a function of temperature, coincident with dielectric measurements. The quantification of polar/nonpolar phases simultaneously is structural description of the polar clusters in relaxor ferroelectrics ceramics. The temperature changes in the polar/nonpolar phase ratio suggest a volume dynamism of the polar clusters as a function of temperature.