Double Spots Research Articles

Sgr A*, M87* and OJ287 as Extreme Central Binaries of Supermassive Black Holes- -Confirmation and extension of decameter radio wave observation results through VLBI data comparison

Based on a deduced 2153±5 s orbiting period of the extreme central binary of the supermassive black hole (ECB-SMBH), at Sgr A*,that is confirmed being based on the decameter radio wave pulse observations compared with 1.3 mm wavelength very long baseline interferometry (VLBI) data from the event horizon telescope (EHT-Data), we depict moving images of Sgr A* from EHT-Data, confirming further the existence of ECB-SMBH. The results show that radio wave images of the two members of ECB-SMBH are radio-bright objects due to emissions caused by source agents accreting from a thick disk toward ECB-SMBH. We extend the confirmed concept of ECB-SMBH to the interpretation of M87*, based on two images released by Miyoshi et al. in 2022 using EHT-Data and by Lu et al. in 2023 using the 3.5 mm wavelength data from the Global Millimeter VLBI Arrays as core telescopes. For the double brilliant spots displayed in two different images of M87*, we consider them the same two objects that shift locations during the 369-day interval of the observation periods of the two images. It is concluded that M87* A and M87* B (temporarily named) are orbiting with a period of 168.8 d at velocities of (6.28±0.54)% and (16.7±1.5)% of the speed of light, respectively. For the existence of ECB-SMBH, the condition of “no gravitational wave radiation” from the SMBH is essential. Regarding the secondary BH of blazar OJ 287, we find around 58~60-year period oscillation of the orbiting period, which is recently in a shortening phase. By applying the concept of ECB-SMBH to the OJ287 primary BH, whose orbiting period is approximately 1.6 yr, we interpret that the orbital period variation of the secondary BH is not due to the radiation of gravitational waves but is caused by the orbital motions of ECB-SMBH

Evaluation method of shale reservoir fracability based on double sweet spots

Evaluation method of shale reservoir fracability based on double sweet spots

Double Spots Based Deep Learning Wavefront Reconstruction and Correction

Double Spots Based Deep Learning Wavefront Reconstruction and Correction

Guiding the Driving Factors on Plasma Super-Photothermal S-Scheme Core-Shell Nanoreactor to Enhance Photothermal Catalytic H2 Evolution and Selective CO2 Reduction.

Light-induced heat has a non-negligible role in photocatalytic reactions. However, it is still challenging to design highly efficient catalysts that can make use of light and thermal energy synergistically. Herein, the study proposes a plasma super-photothermal S-scheme heterojunction core-shell nanoreactor based on manipulation of the driving factors, which consists of α-Fe2 O3 encapsulated by g-C3 N4 modified with gold quantum dots. α-Fe2 O3 can promote carrier spatial separation while also acting as a thermal core to radiate heat to the shell, while Au quantum dots transfer energetic electrons and heat to g-C3 N4 via surface plasmon resonance. Consequently, the catalytic activity of Au/α-Fe2 O3 @g-C3 N4 is significantly improved by internal and external double hot spots, and it shows an H2 evolution rate of 5762.35µmol h-1 g-1 , and the selectivity of CO2 conversion to CH4 is 91.2%. This work provides an effective strategy to design new plasma photothermal catalysts for the solar-to-fuel transition.

Stable expression and multi-site location of Odf2 in mouse oocytes, sperm and early embryos

In mammals, centriole is degenerated during early oogenesis, but it is still not known about the expression and function of centriolar structural components in oocyte meiosis. Here we found that Odf2 (outer dense fiber of sperm tails 2), a key centriolar appendage protein, was stably expressed in mouse oocytes during meiotic progression. Distinct from its single location at centrosomes in somatic mitosis, Odf2 was multiply located at microtubule organizing centers (MTOCs), chromosome centromeres and vesicles in oocyte meiosis. In addition, the vesicle-associated Odf2 disappeared in oocytes treated with the vesicle inhibitor Brefeldin A. Odf2 was mainly co-localized with the mitochondrial sheath in the sperm tail and presented as double spots, similar to γ-tubulin, in the sperm neck region. After fertilization, Odf2 remained on vesicles in embryos from 1-cell to 4-cell stage but was only detected on centrosomes at blastocyst stage. Taken together, Odf2 is expressed precisely in mouse oocytes even in the absence of intact centriole structure, and may regulate oocyte spindle assembly and positioning, additionally, the sperm motility and early embryo development.

Field electron emission and field ion microscope images of layered material MoS2

Field emission microscopy and field ion microscopy (FEM and FIM) of two-dimensional layered material, MoS2, were carried out. MoS2 field emitters were prepared by mechanical peeling of a single crystal and by deposition of MoS2 suspension. FEM exhibited an array of elongated broad spots, and the corresponding FIM images presented patterns consisting of streaked spots and split spots (double spots), depending on electric voltages applied to the emitter. Since the probability of field ionization of imaging gas atoms (Ne gas was used in the present study) is governed by both field strength near surface atomic sites and accessible vacant electronic states, these patterns reflect the atomic site and/or spatial distribution of unoccupied electronic orbitals at the edges of MoS2 layers.

An Unsupervised Machine Learning Based Double Sweet Spots Classification and Evaluation Method for Tight Reservoirs

AbstractWith the increasing exploration and development of tight sandstone gas reservoirs, it is of utmost importance to clarify the characteristics of “sweet spots” within tight gas reservoirs. Considering the complex lithology of tight gas reservoirs, fast phase transformations of sedimentary facies, and vital diagenetic transformation, there is a low success rate of reservoir prediction in the lateral direction, and heterogeneity evaluation is challenging. Establishing a convenient standard for reservoir interpretation in the early stages of development is complex, making designing hydraulic fracturing in the later phases a challenge. In this paper, we propose a detailed study of the engineering and geological double sweet spots (DSS) analysis system and the optimization of sweet spot parameters using the independent weight coefficient method. K-means++ algorithm and Gaussian mixture gradient algorithm unsupervised machine learning algorithms are used to determine the classification standard of general reservoirs and high-quality sweet spot reservoirs in the lower 1 layer of He-8 in the x block of the Sulige gas field. This application of the field example illustrates that the proposed double sweet spot classification and evaluation method can be applied to locate the reservoir’s sweet spot accurately.

Double doughnut-shaped focal spots with controllable position in axial direction

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Double Diffraction or ω-Fe Diffraction in Body-Centered Cubic {112}<111>-Type Twinned Martensite

The martensitic substructure in steels plays a major role in understanding the nature of martensite transformation and improving mechanical properties. However, the substructure in the quenched martensite of carbon steel, particularly in high carbon martensite, has not been clarified yet. Local crystal structure in martensite has been characterized by means of transmission electron microscope (TEM). A specimen tilting experiment in TEM is a practical method to simply confirm that the electron diffraction spots are caused by either double diffraction effect or a second crystalline phase. By tilting the TEM specimen containing Fe–C twinned martensite structure, the so-called double diffraction spots of {112}<111>-type twin are still visible even after the diffraction spots from the twinned crystals become invisible. This experimental result is the direct evidence that the so-called twinning double diffraction spots come from a second crystalline phase (ω-phase), which is distributed in the body-centered cubic (BCC){112}<111>-type twinning boundary region. An ideal BCC {112}<111>-type twin is just a model, which has not been reported yet in any experiment.

Optimization Process of Double Spots Welding of High Strength Steel Using in the Automotive Industry

Resistance Spot Welding (RSW) is one of the most important welding techniques used in the automotive industry because it is an economic process and is suitable for many materials. Many parameters affect the mechanical and microstructural properties of nugget formation and its strength, like welding current, electrode force, and welding time. Therefore, optimizing the RSW process to get the optimum welding parameters is necessary for automobile manufacturing companies. High-strength steel is widely used in the automotive industry because of its superior characteristics such as high strength-weight ratio, ductility, fatigue, and corrosion resistance. This paper presents an optimization process for RSW using the Taguchi method for high strength low alloy steel (HSLA) DOCOL 500 LA, considered a new steel grade. Two spots were used in this work.The mechanical and microstructural tests are achieved to get the maximum nugget strength, nugget diameter, different welding zones microstructures, microhardness values, and failure modes. The results showed that optimum welding parameters were welding current of 8800 Amp, welding time of 20 cycles, and electrode force of 1900 N. The failure mode for optimum conditions was a full pullout with tearing of the welded sheets because of high plastic deformation and absorbed energy. The maximum microhardness value is in the fusion zone, the heat-affected region, and finally, in the base material due to the nugget zone's rapid melting and solidification process.

Generating double focal spots by focusing a radially polarized double-ring-shaped beam with an annular classical axicon

Focusing properties of a radially polarized double-ring-shaped beam with an annular classical axicon are numerically investigated based on vector Debye theory. Double focal spots and a flat-topped beam can be generated by choosing appropriate values of the pupil to the beam ratio β, numerical aperture, and annular obstruction. The distance between the twin spots, their depth of focus and the depth of the flat-topped beam are considerably affected by numerical aperture and annular obstruction. These focal shapes may find applications in laser printing, multifocal microscopy, and material processing.

A Combined Multi-Physics Modelling and Machine Learning to Predict Electro-Thermal Failures of Cylindrical Li-Ion Batteries

Safety aspects of Li-ion batteries (LIBs) operation become increasingly important due to their integration into large-scale systems such as electric vehicles (EVs). Recent events involving many EVs explosions endangering consumers’ lives have shown that electro-thermal aspects of LIBs are far from being adequately managed. Thus, one of the most crucial goals of current research is to steer LIBs’ technology toward long-lasting and safe operation.In this work, we employ data-driven methods to predict and potentially prevent the thermal runaway (TRA) in LIBs. Specifically, we use various machine learning (ML) techniques to learn and predict the likelihood of the TRA, using thermal images acquired from the multi-physics modeling of LIBs. The multi-physics modeling approach is comprised of a coupled thermal, electrochemical (P2D) model1, and degradation due to the solid electrolyte interface (SEI) formation/decomposition sub-models.2 The presented multi-physics model has been formulated as a three-dimensional model to facilitate efficient and accurate numerical simulations in different conditions. Under general working conditions, the cell is exposed to a continuous charge/discharge load, where heat is generated inside the cell due to several electrochemical and degradation processes. Thermal images of the battery surface are collected as sequences of video frames during the battery operation from multiple simulations to be used in ML. LIB’s geometrical and material properties are taken from the 2170 cell as used in the current Tesla vehicles (model S 2021, model 3 2021). Based upon the multi-physics modeling results, two deep learning techniques, i.e., Convolutional Neural Networks (CNN) and object detection using YOLO, are proposed to address the problem of predicting the TRA like-events.3–5 The multi-physics modeling results in the form of the temperature profiles of the battery surface as well as the SEI formation/decomposition rate at various charge/discharge cycles are validated against the prior literature experimental data. Two regimes with single and double hot spots in the cylindrical LIB are investigated for a potential TRA occurrence. The CNN predictions of the TRA-like event on unknown data set show an excellent accuracy reaching up to 90% for all the different CNN architectures used. The object detection technique is found to be very efficient in identifying the location of TRA initiation at various conditions. Thus, the developed combined multi-physics and ML modeling approach establishes a basis for 'on-the-fly' prediction of the TRA as well as a framework for extending machine learning methodologies to broad applications in electrochemistry.References J. Newman and W. Tiedemann, J. Electrochem. Soc., 140, 1–5 (1993).X. Fen, X. He, M. Ouyang, L. Wang, L. Lu, D. Ren and S. Santhanagopalan, J. Electrochem. Soc., 165, A3748–A3765 (2018).J. Redmon, S. Divvala, R. Girshick, and A. Farhadi, Proc. IEEE Comput. Soc. Conf. Comput. Vis. Pattern Recognit., 2016-Decem, 779–788 (2016).K. He, X. Zhang, S. Ren, and J. Sun, Proc. IEEE Comput. Soc. Conf. Comput. Vis. Pattern Recognit., 2016-Decem, 770–778 (2016).K. Simonyan and A. Zisserman, 3rd Int. Conf. Learn. Represent. ICLR 2015 - Conf. Track Proc., 1–14 (2015).

Untying relaxed circular DNA of hepatitis B virus by polymerase reaction provides a new option for accurate quantification and visualization of covalently closed circular DNA.

Hepatitis B virus (HBV) is a small hepatotropic DNA virus that replicates via an RNA intermediate. After entry, the virus capsid carries relaxed circular DNA (rcDNA) into the nucleus where the viral genome is converted into covalently closed circular DNA (cccDNA), which serves as the template for all viral transcripts. To monitor cccDNA levels, preprocessing methods to eliminate rcDNA have emerged for quantitative PCR, although Southern blotting is still the only method to discriminate cccDNA from other DNA intermediates. In this study, we have established a robust method for untying mature rcDNA into double stranded linear DNA using specific polymerases. Untying rcDNA provides not only an alternative method for cccDNA quantification but also a sensitive method for visualizing cccDNA. We combined this method with plasmid-safe DNase and T5 exonuclease preprocessing and revealed that accurate quantification requires cccDNA digestion by a restriction enzyme because heat stability of cccDNA increases after T5 exonuclease treatment. In digital PCR using duplex TaqMan probes, fewer than 1000 copies of cccDNA were successfully visualized as double positive spots that were distinct from single positives derived from untied rcDNA. This method was further applied to the infection model of primary hepatocytes treated with nucleoside analogues and a core protein allosteric modulator to monitor cccDNA levels. Relative quantification of cccDNA by human genome copy demonstrated the possibility of precise evaluation of cccDNA level per nucleus. These results clearly indicate that the sequential reaction from untying rcDNA is useful to investigate cccDNA fates in a small fraction of nuclei.

Effects of hot spot distance on explosive ignition and reaction growth: A reactive molecular dynamics simulation study

Hot spots resulted from shock-induced void collapse could seriously alter the ignition and initial chemical reactions in heterogeneous explosive crystals. Herein, the influences of hot spot distance on ignition and reaction growth in the crystalline RDX were investigated through reactive molecular dynamics simulations. As two voids collapsed completely, double hot spots occurred at the internal upstream and downstream voids in the crystalline RDX, respectively. The farther hot spot distance could be observed in the bulk RDX with the larger void–void distance. Combined with the resulted chemical fragments analysis, hot spot distance affects the chemical reaction rate but does not alter the initial decomposition mechanism in RDX. The farther hot spot distance results in a faster decomposition degree of RDX molecules, a higher concentration of NO2 liberation, and even greater violent growth for explosive reaction. It is evident that RDX with a longer void–void distance is more sensitive to the present overdriven shock. The farther double hot spots result in more RDX molecules being heated simultaneously and then reacted quickly under the synergetic growth of double hot spots. In terms of the synergetic growth of double hot spots, it is demonstrated that reducing hot spot distance could result in decreasing the high-temperature area ratio in the crystalline RDX exposed to an overdriven insult, avoiding the occurrence of a greater violent scenario. The present study can provide an efficient route to understand the role of hot spot distance in ignition and reaction growth and further evaluate the shock sensitivity of crystalline explosives.

Microstructural characterization of early Twentieth‐Century British period Indian copper coins

This investigation deals with the characterization of chemical composition, microstructural, and corrosion behavior of the Indian copper alloy coins belonging to the period of different British emperors (Edward VII, King George V &amp; King George VI). Elemental analysis showed that coins were mainly made up of copper and tin, and other elements such as iron, zinc, nickel, and lead were present in traces. The reddish‐brown layer formed on all coins was identified as cuprite by XRD, and this layer provided protection to the coins. The microstructure consists of an equiaxed grain structure along with annealing twins, which indicate that coins were subjected to annealing heat treatment. The average grain size was measured using the linear intercept method, and the variation in the average grain size of the different coins may be due to the difference in the soaking temperature/time of annealing treatment. TEM study also confirms the formation of twins by showing the double spots in SAD. The higher value of hardness in the coin belonging to the Edward VII period may be attributed to higher tin and zinc content. The corrosion product of globular morphology was observed on the surface of coins. Optical microscopy of the cross‐section of the coins showed the intergranular corrosion phenomena.

Twins or the omega phase: Which is it in high carbon steels?

Electron diffraction coupled with aberration-corrected (AC) scanning transmission electron microscopy (STEM) is used to image, identify and confirm the structure producing double diffracted spots seen in electron diffraction patterns in twinned high-carbon steels. The experimental and simulated data show that regions comprising: (i) overlaps between a twin and the matrix or, (ii) overlapping twins, create projected structures that are similar to the ω phase observed in other metastable bcc systems. Thus, AC STEM is proficient in the definitive identification of twins in bcc high carbon steels or nanoscale phases in metastable bcc systems.

The Stephanidae (Hymenoptera, Stephanoidea) of Iran with the description of a new species

Stephanidae (Hymenoptera, Stephanoidea) are solitary idiobiont ectoparasitoids of wood boring insect larvae. Here we present two genera, i.e., Afromegischus van Achterberg, 2002 and Foenatopus Smith, 1861, and five species, i.e., A. gigas (Schletterer, 1889), F. bisignatus Aguiar &amp; Jennings, 2010, F. crispus Aguiar, 2010, F. nimaarkanii Ghafouri Moghaddam &amp; Rakhshani sp. n. and F. prousti Aguiar &amp; Turrisi, 2010 from Iran. Specimens were collected in southeastern Iran (Kerman and Sistan-o Baluchestan) from unknown hosts. Their morphological features and distribution are discussed in relation to the overall knowledge in the target and adjacent regions. Foenatopus nimaarkanii sp. n. is incorporated to the key for the identification of Foenatopus species with double spots on metasomal tergites.

Temperature dependent magnetization reversal process of a Ga-doped Nd-Fe-B sintered magnet based on first-order reversal curve analysis

A Ga-doped Nd-Fe-B sintered magnet has attracted significant attention as a heavy-rare-earth-free high-performance magnet. We have studied the temperature dependent magnetization reversal process of a Ga-doped Nd-Fe-B sintered magnet based on the first-order reversal curve (FORC) analysis. The FORC diagram pattern of the Ga-doped Nd-Fe-B sintered magnet changes from single spot in the high field region at room temperature to double spots in the low and high field regions at 200 °C, indicating that the dominant magnetization reversal process changes from single domain type to multidomain type. The single domain magnetization reversal at room temperature is well confirmed by using the soft X-ray magnetic circular dichroism microscopy observation. This change in the magnetization reversal process is well discussed by the temperature dependent local demagnetization field and the saturation field of multidomain state. Moreover, we have demonstrated the quantitative analysis of the FORC diagram pattern, which makes a deeper understanding of the magnetization reversal process of the Ga-doped Nd-Fe-B sintered magnet.

Temperature Dependent Magnetization Reversal Process of a Ga-Doped Nd-Fe-B Sintered Magnet Based on First-Order Reversal Curve Analysis

A Ga-doped Nd-Fe-B sintered magnet has attracted significant attention as a heavy-rare-earth-free high-performance magnet. We have studied the temperature dependent magnetization reversal process of a Ga-doped Nd-Fe-B sintered magnet based on the first-order reversal curve (FORC) analysis. The FORC diagram pattern of the Ga-doped Nd-Fe-B sintered magnet changes from single spot in the high field region at room temperature to double spots in the low and high field regions at 200 C, indicating that the dominant magnetization reversal process changes from single domain type to multidomain type. The single domain magnetization reversal at room temperature is well verified using soft X-ray magnetic circular dichroism microscopy observation. This change in the magnetization reversal process is well explained by the temperature dependent saturation field of multidomain grains. Moreover, we have demonstrated the quantitative analysis of the FORC diagram pattern, which makes a deeper understanding of the magnetization reversal process of the Ga-doped Nd-Fe-B sintered magnet.

Simulated electron diffraction patterns of ω-Fe in Fe-C martensite

A metastable hexagonal ω-Fe phase with its particle size of about 1-2 nm coexists at the {112}&amp;lt;111&amp;gt;-type twinning boundaries in Fe-C martensite. The ω-Fe lattice parameters are dependent on their corresponding body centered cubic (BCC) phase (aω=2abcc,cω=3/2abcc). The above dependence and the unique distribution of the ω-Fe particles at the BCC {112}&amp;lt;111&amp;gt;-type twinning boundaries inevitably cause the overlapping of electron diffraction spots of fine ω-Fe with those of BCC and its twin during transmission electron microscope (TEM) observations. Thus, in order to understand the nature of the ultrafine ω-Fe phase in carbon steels, we have simulated its electron diffraction patterns by means of the commercial CrystalMaker software. In most of the zone axes, which show the electron diffraction pattern with three sets of diffraction spots [(1) the BCC matrix crystal, (2) the corresponding twin crystal, and (3) the possible twinning double diffraction spots] together, the simulated results have shown that the diffraction spots from the ω-Fe phase are all overlapped with those three sets of spots. However, in some specific zone axes, for example, in BCC [112] directions, the diffraction spots from the ω-Fe phase can be uniquely recognized since the BCC {112}&amp;lt;111&amp;gt;-type twinning boundary plane is perpendicular to the observation direction, and thus, no twinning double diffraction spots should be observed theoretically.