Double Cluster Research Articles

A Geometry-Based Stochastic Model for Truck Communication Channels in Freeway Scenarios

Vehicle-to-vehicle (V2V) wireless communication systems are fundamental in many intelligent transportation applications, e.g., traffic load control, driverless vehicle, and collision avoidance. Hence, developing appropriate V2V communication systems and standardization require realistic V2V propagation channel models. However, most existing V2V channel modeling studies focus on car-to-car channels; only a few investigate truck-to-car (T2C) or truck-to-truck (T2T) channels. In this paper, a hybrid geometry-based stochastic model (GBSM) is proposed for T2X (T2C or T2T) channels in freeway environments. Next, we parameterize this GBSM from the extensive channel measurements. We extract the multipath components (MPCs) by using a joint maximum likelihood estimation (RiMAX) and then determine the cluster types based on their evolution patterns. We classify the determined clusters into line-of-sight, single-bounce reflections from static interaction objects (IOs), single-bounce reflections from mobile IOs, multiple-bounce reflections, and density multipath components (DMCs). Particularly, we model multiple-bounce reflections as double clusters following the COST 273/COST2100 method. This paper presents the complete parameterization of the channel model. We validate this model by comparing the delay spread and the angular spreads of arrival/departure obtained from the proposed model with the measurement data.

XMM-Newton study of six massive, X-ray luminous galaxy cluster systems in the redshift range z = 0.25–0.5

Massive galaxy clusters are interesting astrophysical and cosmological objects to study, but they are relatively rare. In the redshift range z = 0.25–0.5 which is, for example, a favourable region for gravitational lensing studies, about 100 such systems are known. Most of them have been studied in X-rays. In this paper we study the six remaining massive clusters in this redshift interval in the highly complete CLASSIX (Cosmic Large-Scale Structure in X-rays) survey which have so far not been observed with sufficiently deep exposures in X-rays. With data from our new XMM-Newton observations we characterise their structures, derive X-ray properties such as the X-ray luminosity and intracluster medium temperature, and estimate their gas and total masses. We find that one cluster, RXCJ1230.7+3439, is dynamically young with three distinct substructures in the cluster outskirts and RXCJ1310.9+2157/RXCJ1310.4+2151 is a double cluster system. Mass determination is difficult in the systems with substructure. We therefore discuss several methods of mass estimation including scaling relations. In summary, we find that five of the six targets of study are indeed massive clusters as expected, while the last cluster RXCJ2116.2−0309 is a close projection of a distant and a nearby cluster which has led to a previous overestimation of its mass. In the XMM-Newton observation fields, we also find three low redshift clusters close to the targets which are also analysed and described here. In the field of RXCJ2116.2−0309, we discover serendipitously a highly variable X-ray source which has decreased its flux within a year by more than a factor of eight. This source is most probably an active galactic nucleus (AGN).

Double glassy states and large spontaneous and conventional exchange bias in La1.5Ca0.5CoFeO6 ferrimagnetic double perovskite

The structural and magnetic properties of hole doped double perovskite La1.5Ca0.5CoFeO6 have been investigated by measuring x-ray photoemission spectroscopy, neutron powder diffraction and magnetization. A ferrimagnetic transition is observed at T C∼ 167 K. The presence of anti-site disorder (ASD) in La1.5Ca0.5CoFeO6 has also been demonstrated. Double re-entrant cluster glass transitions (T 1∼ 11 K and TS ∼ 35 K) were observed which has been attributed to the ASD effect. The presence of both large spontaneous exchange bias H SEB ∼ 2.106 kOe and giant conventional exchange bias H CEB ∼ 1.56 T at 5 K has also been observed which can be attributed to the coexistence of long range magnetic ordering and glassy state. The experimental observations were explained with the results obtained by the density functional theory calculation. The presence of double glassy states, large exchange-bias effect and different magnetic phases make this system a potential candidate for spintronic applications.

Ionization potentials and electron affinities of Rg, Cn, Nh, and Fl superheavy elements

The successive ionization potentials (IPs) and electron affinities (EAs) for superheavy elements with $111\ensuremath{\le}Z\ensuremath{\le}114$, namely, Rg, Cn, Nh, and Fl, are reexamined using the relativistic Fock-space coupled-cluster method with nonperturbative single (S), double (D), and triple (T) cluster amplitudes (FS-CCSDT). For most of the considered quantities, the triple-amplitude contributions turn out to be important. The Breit and frequency-dependent Breit corrections are evaluated by means of the configuration-interaction method. The quantum-electrodynamics corrections to the IPs and EAs are taken into account within the model-QED-operator approach. The obtained results are within 0.10 eV uncertainty.

Reentrant double glassy states and simultaneous presence of short- and long-range ordering in metamagnetic Co-doped Bi0·5La0·5Fe0·5Mn0·5O3 multiferroic

A study of the structural and magnetic properties of Bi0·5La0·5Fe0·45Co0·05Mn0·5O3 is presented in the article. We report the rare observations of two glassy transitions below the long-range ordering temperature along with the metamagnetic transitions at low temperatures. Frequency and DC field dependence of AC susceptibility and isothermal relaxation of remnant magnetization studies have all shown the slow spin dynamics for the compound. Interestingly, in the glass phase of the materials, metamagnetic transitions of the antiferromagnetic spins were found which indicate the coexistence of the long-range ordered phase along with the short-range ordered glassy phase. The double cluster glass phases can be comprehended, from the relaxations of the spin clusters arising from the competing magnetic interactions present in the system. Moreover, the roles of additional exchange interactions which are brought to the system by Co doping are also considered in explaining the observed double cluster glass transitions.

Structure, dynamics and melting of 19-atom double icosahedral silver cluster

In this paper, the structural and dynamical properties of the 19-atom double icosahedral silver cluster are studied by using the classical molecular dynamics. It is found that the melting of the 19-atom cluster starts with the migrations of the surface atoms. The surface atoms can interchange positions with each other atoms through three ways. The first and second ways involve with only part of the surface atoms. The third way can involve the surface atoms at all symmetrical positions. With the increase of temperature, the inner atoms can hop onto the surface of the cluster and the position interchange between the surface atoms and the inner atoms can be realized. With further increase of temperature, the isomerization of the cluster becomes frequent and the motion of the atoms of the cluster becomes more and more disordered. When the temperature reaches the value corresponding to the second peak of the heat capacity, the solid cluster turns into the fully melted state.

MUSE spectroscopic observations of the young massive cluster NGC 1850

Context. The double cluster NGC 1850 in the Large Magellanic Cloud is the nearest young massive cluster of the Local Group with a mass similar to those of Galactic globular clusters. Recent studies have revealed an extended morphology of its main-sequence turn-off (MSTO), which can be interpreted as a spread in either age or internal rotation. In spite of its proximity, an accurate spectroscopic determination of its chemical properties is still missing. Aims. We aim to investigate the general chemistry and the kinematics of this stellar system to test whether possible signs of multiple populations are observable in this cluster. Methods. We analysed the spectra obtained with MUSE in adaptive optics mode of 1167 stars in both components of this cluster (NGC 1850A and NGC 1850B). Thanks to this data set, we were able to measure accurate global metallicities, Ba abundances, and radial velocities for a sample of 38 red supergiants and a guess of the oxygen abundance in the brightest turn-off stars belonging to NGC 1850A. Results. We find an average metallicity of ⟨[M/H]⟩ = −0.31 ± 0.01, a mean Ba abundance of ⟨[Ba/Fe]⟩ = +0.40 ± 0.02, and a systemic radial velocity of ⟨vLOS⟩ = 251.1 ± 0.3 km s−1. The dispersion of the radial velocities suggests a dynamical mass of log(M/M⊙) = 4.84 ± 0.1, while no significant systemic rotation is detected. We detect a significant bimodality in O I line strength among the turn-off stars of NGC 1850A with ∼66% of stars with [O/Fe]∼ − 0.16 and the rest with no detectable line. The majority of O-weak stars preferentially populate the red side of the MSTO and show H lines in emission, suggesting that they are Be stars rotating close to their critical velocity. Among normal MSTO stars, red stars have broader line profiles than blue ones, on average, suggesting a correlation between colour and rotational velocity. Conclusions. The mean metallicity of this cluster lies at the metal-rich side of the metallicity distribution of the Large Magellanic Cloud following its age-metallicity relation. The Ba and O abundances agree with those measured in the bar of this galaxy. The correlation between line broadening and colour suggests that the observed colour spread among turn-off stars can be due to a wide range in rotational velocity covered by these stars.

Evidence of room temperature magnetodielectric and cluster glass behavior of Sr substituted Y-type Ba2Mg2Fe11.48Mn0.52O22 hexaferrite

We have presented a systematic study on structural, magnetic, and magnetodielectric (MD) properties of Y-type Ba2-xSrxMg2Fe11.48Mn0.52O22 (0 < x ≤ 1) hexaferrite. The temperature-dependent DC magnetization results exhibit Sr substitution enhances spin ordering transition temperature TI (TII) from 52 K (210 K) to 73 K (315 K). AC magnetic characterization suggests the presence of single cluster-glass transition (Tf1) at 45 K for x = 0.25. Interestingly, for higher Sr substitution x > 0.25, double cluster class transition is observed. The freezing temperature Tf1 decreases with an increase in x, while Tf2 increases substantially with x. The saturation magnetization (Ms) value is found to be decreased from 28.88 emu/g for x = 0.25 to 26.28 emu/g for x = 0.75 at 300 K. However, for x > 0.75 this value increases. Raman modes at 78, 135, 335, and 694 cm−1 show a gradual increase in Raman shift up to x = 0.75, but a drastic decrease is seen for x > 0.75. Along with enhanced magnetic properties, Sr doped sample shows better MD properties. The MD% value at RT increases with doping concentration up to x = 0.75 (MD% ∼1.2); beyond that, its value decreases. The maximum value of frequency-independent MD% and magnetoloss ML% of the BSMFM25 is found to be ∼3.5 and ∼0.2, respectively in the presence of a 1.3 T field at 100 Hz. The H-dependent MD exhibits symmetric anomalies close to the H-induced transition indicating an exchange-striction phenomenon in the samples.

Reanalysis of 6Li+90Zr angular distributions using different nuclear potentials

The experimental angular distributions for 6Li elastically scattered from a 90Zr target in the energy range 14.89–240 MeV are theoretically reanalyzed using phenomenological and semi-microscopic potentials. The phenomenon of the break-up threshold anomaly (BTA) is well represented in the various used potentials. In analyzing nuclear systems induced by weakly bound projectiles such as 6Li, the well-known reduction in the strength of the real part of potential generated based on double folding (DF) and cluster folding (CF) models is also observed. The Sao Paulo potential (SPP) is used to perform double folding calculations. In order to fit the data fairly, a reduction of ∼ 42% and 45% in the strength of the microscopic real part of potential constructed using SPP and CFM, respectively, is found to be required. By including an additional dynamical polarization potential, the data are also reproduced without renormalizing the real cluster folding potential.

Abstract PD6-04: Mutational landscape and immune infiltration of breast cancer metastases to gynecologic and other organs

Abstract Introduction: Breast cancer metastases (BCM), which cause most breast cancer (BC)-associated mortality, have increased genetic complexity compared to early-stage disease. However, the contribution of genetic alterations to site of BCM is not well-understood. Different breast cancer subtypes have varying patterns of BCM, e.g., lobular carcinoma more frequently spreads to gynecologic (Gyn) organs and the GI tract, perhaps hinting at selection pressures wherein some organs are hospitable to tumors with certain genetic alterations. Methods: Relationships between BCM site and mutations detected by DNA next-generation sequencing (NGS; NextSeq 592 gene panels or NovaSeq whole exome sequencing) were investigated using 12,464 BC samples sequenced at Caris Life Sciences (sample sizes, Table 1). PD-L1 expression was tested through IHC (Clone SP-142 (cut-off ≥1, 1%)). Tumor mutational burden (TMB) was measured by totaling somatic mutations per tumor (high ≥ 10 mutations per MB). Immune cell fractions were calculated by deconvolution of whole-transcriptome data (NovaSeq) using Quantiseq (reference). Statistical significance was determined using chi-square and Wilcoxon rank sum tests adjusted for multiple comparisons. Results: Compared to primary breast tumors, BCM had increased frequency of TMB-H (10.08% vs. 4.94%), decreased PD-L1 positivity (21.09% vs. 35.82%), and were enriched for PIK3CA (34.62% vs 30.53%) and ESR1 mutations (13.34% vs 2.17%) (all P&amp;lt;0.001). PD-L1 positivity was highest in BCM to lymph nodes (43.06%) and axilla (39.77%). BCM to Gyn organs had more lobular histology, the highest rate of hormone receptor (HR)+ tumors (77.17%), and rarely had high TMB (6.73%) or were PD-L1 positive (11.39%). Double dendrogram hierarchical clustering of BCM site by mutation frequency and pathway alterations revealed BCM to Gyn organs as a simplicifolious clade with a unique mutational pattern. Compared to BC in breast, BCM to Gyn organs had higher rates of mutations of PIK3CA, AKT1, and BRAF; more mutations in DNA repair (0.79% vs 0.06%), transcription factor (4.72% vs 0.93%), and Wnt signaling pathways (2.36% vs 1.47%); but no increase in BRCA mutations. BCM to brain had the most p53 pathway and homologous recombination (HR) pathway mutations (64.71% and 14.01%), while Gyn had the least (19.69% and 7.09%). Quantiseq RNA deconvolution revealed differences in tumor immune cell infiltrate by BCM site. Gyn metastases vs breast tumors had increased B cells (6.20% vs 5.40%), M2 macrophages (5.71% vs 4.07%), and NK cells (3.82% vs 3.18%) (all P&amp;lt;0.01) and a M2/M1 macrophage ratio of 22.8:1 vs 1.3:1. Conclusions: BCM to Gyn organs have a unique mutational and immune suppression profile. Integrating the profiling with clinical outcomes may extend this prognostic signature and set the stage for improved treatment strategies for these patients. Confirmation from matched or sequential specimens could clarify tumor evolution. Our data support repeat biopsy of Gyn site metastases since more targetable mutations might be revealed. Targeting mechanisms of immunosuppression in Gyn BCM could expand therapeutic options. Table 1.Breast Cancer TumorsTumor SiteTotalPredominant Breast Cancer SubtypeAll12464HR+/HER2- (51.6%)Breast5014HR+/HER2- (46.5%)Liver2003HR+/HER2- (63.3%)Bone1132HR+/HER2- (69.4%)Axilla1051HR+/HER2- (47.7%)Lung823HR+/HER2- (46.1%)Lymph Node647HR+/HER2- (43.4%)Chest/Chest Wall375HR+/HER2- (44.8%)Brain359TNBC (38.2%)Other315HR+/HER2- (57.1%)Skin282HR+/HER2- (50.7%)Connective Tissue193HR+/HER2- (51.8%)GI Organs143HR+/HER2- (69.9%)Gynecologic Organs127HR+/HER2- (76.4%) Citation Format: Anna D Louie, Rani Chudasama, Sharon Wu, Marzia Capelletti, Daniel Magee, W. Michael Korn, Virginia Kaklamani, Antoinette R Tan, Pavani Chalasani, Wafik S El-Deiry, Don Dizon, Stephanie L. Graff. Mutational landscape and immune infiltration of breast cancer metastases to gynecologic and other organs [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD6-04.

The Effect of Age on the Grouping of Open Clusters: The Primordial Group Hypothesis

The Primordial Group hypothesis states that only sufficiently young open clusters (OCs) can be multiple, and old OCs are essentially isolated. We tested this postulate through four different studies using a manual search of Gaia EDR3 and extensive literature. First, we revisited the work of de La Fuente Marcos and de La Fuente Marcos (2009), which states that only ca. 40% of OC pairs are of primordial origin. However, no plausible binary system among their proposed OC pairs having at least one member older than 0.1 Gyr was found. Second, we researched the OCs &lt; 0.01 Gyr old in Tarricq et al. (2021) and found that ca. 71% of them remain in their primordial groups. Third, a similar study of the oldest OCs (age &gt; 4 Gyr) showed that they are essentially alone. Forth, the well-known case of the double cluster in Perseus and some other binary systems described in the literature were also shown to accommodate the title hypothesis. A simplified bimodal model allows for retrieval of the overall fraction of related OCs (approximately 12–16%) from our results, assuming that young clusters remain associated at ~0.04 Gyr. The obtained results further support that OCs are born in groups (Casado 2021).

Dosimetry of heavy ion exposure to human cells using nanoscopic imaging of double strand break repair protein clusters

The human body is constantly exposed to ionizing radiation of different qualities. Especially the exposure to high-LET (linear energy transfer) particles increases due to new tumor therapy methods using e.g. carbon ions. Furthermore, upon radiation accidents, a mixture of radiation of different quality is adding up to human radiation exposure. Finally, long-term space missions such as the mission to mars pose great challenges to the dose assessment an astronaut was exposed to. Currently, DSB counting using γH2AX foci is used as an exact dosimetric measure for individuals. Due to the size of the γH2AX IRIF of ~ 0.6 µm, it is only possible to count DSB when they are separated by this distance. For high-LET particle exposure, the distance of the DSB is too small to be separated and the dose will be underestimated. In this study, we developed a method where it is possible to count DSB which are separated by a distance of ~ 140 nm. We counted the number of ionizing radiation-induced pDNA-PKcs (DNA-PKcs phosphorylated at T2609) foci (size = 140 nm ± 20 nm) in human HeLa cells using STED super-resolution microscopy that has an intrinsic resolution of 100 nm. Irradiation was performed at the ion microprobe SNAKE using high-LET 20 MeV lithium (LET = 116 keV/µm) and 27 MeV carbon ions (LET = 500 keV/µm). pDNA-PKcs foci label all DSB as proven by counterstaining with 53BP1 after low-LET γ-irradiation where separation of individual DSB is in most cases larger than the 53BP1 gross size of about 0.6 µm. Lithium ions produce (1.5 ± 0.1) IRIF/µm track length, for carbon ions (2.2 ± 0.2) IRIF/µm are counted. These values are enhanced by a factor of 2–3 compared to conventional foci counting of high-LET tracks. Comparison of the measurements to PARTRAC simulation data proof the consistency of results. We used these data to develop a measure for dosimetry of high-LET or mixed particle radiation exposure directly in the biological sample. We show that proper dosimetry for radiation up to a LET of 240 keV/µm is possible.

Multiwavelength Analysis of A1240, the Double Radio-relic Merging Galaxy Cluster Embedded in an ∼80 Mpc-long Cosmic Filament

Abstract We present a multiwavelength study of the double radio-relic cluster A1240 at z = 0.195. Our Subaru-based weak-lensing analysis detects three mass clumps forming an ∼4 Mpc filamentary structure elongated in a north–south orientation. The northern ( M 200 = 2.61 − 0.60 + 0.51 × 10 14 M ⊙ ) and middle ( M 200 = 1.09 − 0.43 + 0.34 × 10 14 M ⊙ ) mass clumps separated by ∼1.3 Mpc are associated with A1240 and colocated with the X-ray peaks and cluster galaxy overdensities revealed by Chandra and MMT/Hectospec observations, respectively. The southern mass clump ( M 200 = 1.78 − 0.55 + 0.44 × 10 14 M ⊙ ), ∼1.5 Mpc to the south of the middle clump, coincides with the galaxy overdensity in A1237, the A1240 companion cluster at z = 0.194. Considering the positions, orientations, and polarization fractions of the double radio relics measured by the LOFAR study, we suggest that A1240 is a postmerger binary system in the returning phase with a time since collision of ∼1.7 Gyr. With the SDSS DR16 data analysis, we also find that A1240 is embedded in the much larger scale (∼80 Mpc) filamentary structure whose orientation is in remarkable agreement with the hypothesized merger axis of A1240.

Magnetospheric Physics in China: 2020–2021

In the past two years, many progresses have been made in magnetospheric physics by using the data of Double Star Program, Cluster, THEMIS and RBSP missions, or by computer simulations. This paper briefly reviews these works based on papers selected from the 126 publications from March 2012 to March 2014. The subjects cover various sub-branches of magnetospheric physics,including geomagnetic storm, magnetospheric substorm and magnetic reconnection.

PSZ2 G091: A massive double cluster atz~ 0.822 observed by the NIKA2 camera

PSZ2 G091.83+26.11 is a massive galaxy cluster withM500= 7:43 × 1014M⊙atz= 0:822. This object exhibits a complex morphology with a clear bimodality observed in X-rays. However, it was detected and analysed in thePlancksample as a single, spherical cluster following a universal profile [1]. This model can lead to miscalculations of thermodynamical quantities, like the pressure profile. As future multiwavelength cluster experiments will detect more and more objects at higher redshifts (where we expect the fraction of merging objects to be higher), it is crucial to quantify this systematic effect. In this work, we use high-resolution observations of PSZ2 G091.83+26.11 by the NIKA2 camera to integrate the morphological characteristics of the cluster in our modelling. This is achieved by fitting a two-halo model to the SZ image and then by reconstruction of the resulting projected pressure profile. We then compare these results with the spherical assumption.

Incremental Linear Discriminant Analysis Dimensionality Reduction and 3D Dynamic Hierarchical Clustering WSNs

Optimizing the sensor energy is one of the most important concern in Three-Dimensional (3D) Wireless Sensor Networks (WSNs). An improved dynamic hierarchical clustering has been used in previous works that computes optimum clusters count and thus, the total consumption of energy is optimal. However, the computational complexity will be increased due to data dimension, and this leads to increase in delay in network data transmission and reception. For solving the above-mentioned issues, an efficient dimensionality reduction model based on Incremental Linear Discriminant Analysis (ILDA) is proposed for 3D hierarchical clustering WSNs. The major objective of the proposed work is to design an efficient dimensionality reduction and energy efficient clustering algorithm in 3D hierarchical clustering WSNs. This ILDA approach consists of four major steps such as data dimension reduction, distance similarity index introduction, double cluster head technique and node dormancy approach. This protocol differs from normal hierarchical routing protocols in formulating the Cluster Head (CH) selection technique. According to node’s position and residual energy, optimal cluster-head function is generated, and every CH is elected by this formulation. For a 3D spherical structure, under the same network condition, the performance of the proposed ILDA with Improved Dynamic Hierarchical Clustering (IDHC) is compared with Distributed Energy-Efficient Clustering (DEEC), Hybrid Energy Efficient Distributed (HEED) and Stable Election Protocol (SEP) techniques. It is observed that the proposed ILDA based IDHC approach provides better results with respect to Throughput, network residual energy, network lifetime and first node death round.

Pseudoeosinophilia with Abnormal WBC Scattergram: an Important Diagnostic Clue on Hematology Analyzer

Malaria is one of the most common parasitic diseases causing a significant burden on health care, especially in India. Light microscopy, the gold standard for malaria diagnosis is time-consuming especially in a setup where the caseload is high and parasite index is low. Knowledge of abnormal scattergrams by the malarial parasite is very essential to suspect malaria and screen those cases thoroughly on a peripheral smear for accurate diagnosis. A timely and accurate diagnosis is crucial to the prognosis of this disease. Herein, we report a case of a 40-year-old male from Punjab who presented to the emergency with fever and an altered sensorium. Analyzer showed characteristic pseudo eosinophilia with greying of neutrophil eosinophil zone with double eosinophil cluster. According to flagging rules because of eosinophilia, peripheral blood film (PBF) was made and examined, which revealed Plasmodium falciparum gametocytes.

Exploring the Role of Cluster Formation in UiO Family Hf Metal-Organic Frameworks with in Situ X-ray Pair Distribution Function Analysis.

The structures of Zr and Hf metal-organic frameworks (MOFs) are very sensitive to small changes in synthetic conditions. One key difference affecting the structure of UiO MOF phases is the shape and nuclearity of Zr or Hf metal clusters acting as nodes in the framework; although these clusters are crucial, their evolution during MOF synthesis is not fully understood. In this paper, we explore the nature of Hf metal clusters that form in different reaction solutions, including in a mixture of DMF, formic acid, and water. We show that the choice of solvent and reaction temperature in UiO MOF syntheses determines the cluster identity and hence the MOF structure. Using in situ X-ray pair distribution function measurements, we demonstrate that the evolution of different Hf cluster species can be tracked during UiO MOF synthesis, from solution stages to the full crystalline framework, and use our understanding to propose a formation mechanism for the hcp UiO-66(Hf) MOF, in which first the metal clusters aggregate from the M6 cluster (as in fcu UiO-66) to the hcp-characteristic M12 double cluster and, following this, the crystalline hcp framework forms. These insights pave the way toward rationally designing syntheses of as-yet unknown MOF structures, via tuning the synthesis conditions to select different cluster species.

The role of QED effects in transition energies of heavy-atom alkaline earth monofluoride molecules: A theoretical study of Ba+, BaF, RaF, and E120F.

Heavy-atom alkaline earth monofluoride molecules are considered as prospective systems to study spatial parity or spatial parity and time-reversal symmetry violating effects such as the nuclear anapole moment or the electron electric dipole moment. A comprehensive and highly accurate theoretical study of the electronic structure properties and transition energies in such systems can simplify the preparation and interpretation of the experiments. However, almost no attempts to calculate quantum electrodynamics (QED) effects' contribution into characteristics of these neutral heavy-atom molecules have been performed. Recently, we have formulated and implemented such an approach to calculate QED contributions to transition energies of molecules [L. V. Skripnikov, J. Chem. Phys. 154, 201101 (2021)]. In this paper, we perform a benchmark theoretical study of the transition energies in the Ba+ cation and BaF molecule. The deviation of the calculated values from the experimental ones is of the order 10 cm-1 and is more than an order of magnitude better than the "chemical accuracy," 350 cm-1. The achievement of such an agreement has been provided, in particular, by the inclusion of the QED effects. The latter appeared to be not less important than the high-order correlation effects beyond the coupled cluster with single, double, and perturbative triple cluster amplitude level. We compare the role of QED effects for transition energies with heavier molecules-RaF and E120F, where E120 is the superheavy Z = 120 homologof Ra.

Simulation of multi-cluster fracture propagation by hydraulic fracturing in shale reservoir

China is rich in shale oil resources. With the continuous breakthrough of exploitation technology, shale oil has become an important strategic oil resource in China. As it turns out, Multi-cluster fracturing technology of horizontal well is an efficient method to produce shale oil. However, most of the research on the initiation and propagation of fractures in shale reservoirs is based on numerical simulation. In this paper, through the improved true triaxial hydraulic fracturing physical simulation system, the rock multi-cluster fracturing physical simulation experiment, obtain the fracturing process parameters, and analyze the mechanism of fracture generation. The numerical model of fracture is established to analyze the interfracture interference phenomenon and optimize the segmenting and clustering problem. The results showed that: The larger the fracturing fluid viscosity is within a certain range, the smaller the probability of fracturing fluid leakage is, and the more conducive to the formation of fractures; Cluster spacing has a great influence on fracture propagation. Compared with double clusters, three clusters of fractures are more conducive to forming effective fractures. This paper comprehensively considers the multi-field coupling effect in the fracturing process, deeply understands the mechanical parameters of natural fractures, improves the understanding of the regularity of mechanical parameters of natural fractures under the multi-field coupling effect of fluid-solid-temperature, and provides further guidance for the optimization design of fracturing parameters.