Density matrix of chaotic quantum systems Yang, Xinxin; Wang, Pei
The European physical journal. B, Condensed matter physics,
10/2020, Letnik:
93, Številka:
10
Journal Article
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Odprti dostop
The nonequilibrium dynamics in chaotic quantum systems denies a fully understanding up to now, even if thermalization in the long-time asymptotic state has been explained by the eigenstate ...thermalization hypothesis which assumes a universal form of the observable matrix elements in the eigenbasis of Hamiltonian. It was recently proposed that the density matrix elements have also a universal form, which can be used to understand the nonequilibrium dynamics at the whole time scale, from the transient regime to the long-time steady limit. In this paper, we numerically test these assumptions for density matrix in the models of spins.
Graphical abstract
Growth strata are important for understanding regional tectonic evolution. However, it is difficult to identify growth strata in the field, because of subsequent intensive modification and erosion. ...To address this problem, we studied two paleomagnetic sections at the stable deposition setting and the growth end of the Miocene growth strata of the Gengma Basin. Average inclinations of the two sections show a systematic deviation of 4.7° ± 5.2°. The anisotropy of magnetic susceptibility results for the growth end of the section A demonstrate a sedimentary fabric. However, the tilt‐corrected K3 axis deviates to the southwest from the normal direction of the bedding by 5.4° ± 3.8°, the magnetic foliation deviates to the equatorial plane by 5.3° ± 4.7°. The K3 axis is perpendicular to the bedding at the stable deposition setting. The deviation of the K3 axis from the normal direction of bedding is interpreted as the growth angle, which can be used to correct the paleomagnetic inclination data.
Plain Language Summary
Growth strata are linked with tectonic deformation, and so they are often used as an indicator for analyzing regional tectonics. However, it is difficult to directly identify growth strata in the field, due to typically strong structural deformation. Additionally, unidentified growth strata often lead to the inaccurate correction of the paleomagnetic data, which is a source of uncertainty in estimating for the paleolatitudes of blocks. The Gengma Basin in the north of the Shan‐Tai Block is a typical graben basin. Paleomagnetic and anisotropy of magnetic susceptibility (AMS) data of Miocene growth strata show that the paleo‐inclination of the growth end deviates from that of the stable depositional setting. Moreover, the tilt‐corrected K3 axis of the sedimentary fabric at the growth end deviates from the normal to bedding by 5.4° ± 3.8°, and the magnetic foliation deviates from the equatorial plane by 5.3° ± 4.7°. However, the tilt‐corrected K3 axis at the stable deposition setting is consistent with the normal to bedding. The differences in the paleo‐inclinations and AMS results between the growth end and the stable depositional setting can be used to identify the growth strata, and to correct the paleo‐inclination.
Key Points
The paleo‐inclination and anisotropy of magnetic susceptibility data at the growth end of the growth strata were over‐corrected
Offset angle of the K3 axis of sedimentary fabric deviating from the normal direction of the bedding is the growth angle of growth strata
The offset angle of the K3 axis of the sedimentary fabric can be used to identify growth strata and precisely correct paleo‐inclination
Fourteen polybrominated diphenyl ether (PBDE) congeners were measured in water, suspended particulate matter (SPM), and sediment samples collected from the entire expanse of the Yellow River in dry ...and wet seasons. Higher concentrations of PBDEs were found in the middle and lower reaches of the river compared with those in the upper reaches, ascribed to the relatively developed and urbanized cities located in the areas near the middle and lower reaches. The PBDE concentrations in the samples collected during the dry season were lower than those in the samples collected during the wet season because of thaw and rainfall. The dominant congener, with a contribution of 44.6–90.3%, was BDE-209, which originated from the residual of commercial deca-BDE. Three groups of congeners in all the samples showed good correlations with the coefficient ranging from 0.662 to 0.999 (p < 0.01), indicating common sources and similar environmental behaviors. Regression analysis suggested that the local industrial product (IP) and population density (PD) were good indicators of PBDEs in the water and sediment of the Yellow River.
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•14 PBDEs were investigated in multi phases along the whole Yellow River for two seasons.•Higher level PBDEs in middle and lower reaches caused by industrial activities.•SPM contained relatively high PBDEs due to the high sediment concentration in Yellow River.•Local industrial product and population density were good indicators of PBDEs.
Anthocyanins are natural water-soluble pigments that are important in plants because they endow a variety of colors to vegetative tissues and reproductive plant organs, mainly ranging from red to ...purple and blue. The colors regulated by anthocyanins give plants different visual effects through different biosynthetic pathways that provide pigmentation for flowers, fruits and seeds to attract pollinators and seed dispersers. The biosynthesis of anthocyanins is genetically determined by structural and regulatory genes. MYB (
avian myeloblastosis viral oncogene homolog) proteins are important transcriptional regulators that play important roles in the regulation of plant secondary metabolism. MYB transcription factors (TFs) occupy a dominant position in the regulatory network of anthocyanin biosynthesis. The TF conserved binding motifs can be combined with other TFs to regulate the enrichment and sedimentation of anthocyanins. In this study, the regulation of anthocyanin biosynthetic mechanisms of MYB-TFs are discussed. The role of the environment in the control of the anthocyanin biosynthesis network is summarized, the complex formation of anthocyanins and the mechanism of environment-induced anthocyanin synthesis are analyzed. Some prospects for MYB-TF to modulate the comprehensive regulation of anthocyanins are put forward, to provide a more relevant basis for further research in this field, and to guide the directed genetic modification of anthocyanins for the improvement of crops for food quality, nutrition and human health.
A novel shape-stabilized phase change material was successfully prepared using polyethylene glycol (PEG) as phase change material (PCM) and mesoporous carbon FDU-15 as support via the melting ...impregnation method. The structural and thermal properties of materials were measured by TEM, SEM, XRD, FT-IR, nitrogen adsorption-desorption isotherms and DSC, respectively. The maximum loading of PEG/FDU-15 reaches up to 75 wt%, and the corresponding crystallization ratio is 71%, which is superior to other mesoporous-based composite PCMs. Molecular dynamic (MD) analysis showed that some PEG adhered to the pore wall with an amorphous structure which failed to crystallize, ultimately resulting in a gap between the measured latent heat and the theoretical value. It was interesting that the filling of PEG could stimulate the frequency shift of atomic vibration in FDU-15, which then just fell in the dominant vibrational zone of PEG, despite the suppressed atomic vibration of PEG after compounding. Accordingly, the thermal conductivity of the composite is more than 60% higher compared to pure PEG, which relates to the reinforced matching of the atomic vibration between the skeleton and PCM material. FDU-15 was applied to pack PCM for the first time and delivered a better thermal performance compared with other mesopore-based composite PCMs.
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•Mesoporous carbon FDU-15 was successfully applied to prepare a novel low temperature composite phase change material PEG/FDU-15.•The composite received a 63%-fold increase in thermal conductivity, and superior loading and crystallization behavior over other mesopore-based counterparts.•The molecular dynamic analysis pointed out a frequency shift of atom vibration in FDU-15 thus a better match with PEG.
Solid-liquid phase change material (PCM) is the key factor for the development of thermal energy storage (TES) technology, which substantially contributes to the utilization of renewable energy and ...improving the energy conversion efficiency. However, some inherent problems (e.g. leakage and corrosion during the phase change process) limit the performance of PCMs. The immobilization of PCMs into a nanoporous scaffold in order to derive shape-stabilized composite PCMs (ssPCMs) has been defined as an effective way to overcome above drawbacks. Moreover, it is profitable to explore other properties, such as flame retarding property, magnetic and thermal conduction, and photovoltaic conversion, which are entirely introduced by porous materials. So, this paper reviews the present state of the art of nanoporous ssPCMs, summarizes from the aspects of fabrication, structural and thermal property characterization, and the solutions for thermal performance enhancement. Owing to the confinement, the phase change property will be quite different with pure PCMs considering the size effect and interface effect. We aim to access the controllable parameters which directly affect guest-host interaction via summarizing the progress on molecular dynamics (MD) modeling and prediction. Finally, the challenges and prospective solutions associated with ssPCMs are also provided.
•State-of-the-art review of nanoporous composite PCMs is comprehensively presented.•Fabrication and physicochemical/thermal characterization of ssPCMs is reviewed.•Enhancement in storage capacity, thermal conductivity and retardancy is introduced.•MD modeling of thermal properties and confinement mechanism in ssPCMs is discussed.•The future challenges and research priorities for ssPCMs are prospected.
Developing novel shape-stabilized phase change materials (ssPCMs) is of vital importance in utilization of thermal energy. In addition, the reveal of interaction mechanism between PCM and supporter, ...is a prerequisite for design and synthesis of ssPCMs. In this study, PEG was filled into mesoporous silica MCM-41 via the solution impregnation method to prepare composite PCMs. The -NH2 groups were successfully grafted onto the surface of MCM-41, by replacing original -OH groups. It turns out that the phase transition of PEG did not occur in hydroxyl-modified MCM-41 even at the maximum loading of 70 wt%. Excitingly, after amino modifying, the composite PCMs had superior properties compared with PEG/MCM-41-OH. The phase change was available even at 30 wt% loading and the phase change enthalpy was increased from 0 J/g to 58.76 J/g. Furthermore, the ssPCM exhibited good thermal reliability after the thermal cycling. Mechanism within the experimental phenomena was studied by molecular dynamics method. Excessive adsorption occurs at the nanochannel surface under the strong interaction between -OH groups and PEG molecules thus restrains the phase transition of PEG. Amino groups reduced the host-guest hydrogen bonding interaction, which is conducive to PEG crystallizing. It is concluded that the PEG/MCM-41-NH2 is a promising candidate for use as low temperature solar energy storing due to the improved properties and simple operation. Moreover, MD results suggested that the host-guest interaction could be regulated by surface modifying therefore to control the loading and crystallization behavior of PEG in MCM-41, and the methodology can be extended to other nanoporous-based PCMs.
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•Low temperature composite PCM PEG/MCM-41was fabricated.•The PEG/MCM-41-NH2 showed superior phase change performance than PEG/MCM-41-OH.•The underlying mechanism was investigated by MD simulation, and host-guest polarity matching was proposed for ssPCM design.
The core-shell structure molecularly imprinted magnetic nanospheres towards hypericin (Fe₃O₄@MIPs) were prepared by mercapto-alkyne click polymerization. The shape and size of nanospheres were ...characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). The nanospheres were analyzed by FTIR spectroscopy to verify the thiol-yne click reaction in the presence or absence of hypericin. The Brunauer⁻Emmet⁻Teller (BET) method was used for measuring the average pore size, pore volume and surface area. The Fe₃O₄@MIPs synthesized displayed a good adsorption capacity (
= 6.80 µmol·g
). In addition, so-prepared Fe₃O₄@MIPs showed fast mass transfer rates and good reusability. The method established for fabrication of Fe₃O₄@MIPs showed excellent reproducibility and has broad potential for the fabrication of other core-shell molecularly imprinted polymers (MIPs).
•Tensile strength development of concrete with manufactured sand (MSC) was tested.•Effect of stone powder content on tensile strength development of MSC was examined.•Statistical relation of tensile ...strength to compressive strength at any curing time.•Formulas predicting long-term tensile strength of MSC are proposed.
Concrete with manufactured sand (MSC) is a potential environmental friendly building material. As the limited study on tensile strength development of MSC, the findings of research work are presented in this paper. The MSC cubes were tested by the splitting tensile method, the influences that the water-cement ratio and the stone powder content have on the tensile strength development of MSC were analyzed. Test results showed that manufactured sand with no more than 13% stone powder content was beneficial to the long-term tensile strength of MSC. Forecast models are suggested for the prediction of long-term tensile strength of MSC.
The Eastern Himalayan Syntaxis (EHS) is a major structural and geomorphological unit in Eastern Tibet; however, its mechanism of formation and the extent of its northward effect of compression remain ...unclear. To address these questions, we conducted a paleomagnetic and geochronologic study of the late Eocene trachyte intrusive mass in the Mangkang area of Tibet. The U-Pb SHRIMP II age estimate of the trachyte intrusive mass is ∼40 Ma, and the estimated mean paleomagnetic direction we obtained is D=27.0°, I=36.8°, k=42.9, α95=1.3°, and n=282 specimens. These results indicate that the Mangkang area was located at a paleolatitude of 20.5 ± 0.9° N during the late Eocene. A comparison of paleolatitudes of the Qiangtang block with those inferred from the apparent polar wander paths (APWP) of India and Eurasia suggests that the Eastern Himalayan Syntaxis was formed after 35 Ma when Eurasia was penetrated by ∼600 km by northward-moving India. This is consistent with geologic evidence of intra-continental shortening in the foreland of the Eastern Himalayan syntaxis. The northward counterclockwise penetration of the corner of India also resulted in the large right-lateral strike-slip system of the Sagaing fault (SGF), with ∼400-600 km of displacement between the EHS and the Shan-Thai block. Thus, the northward wedging of the EHS indicates minimal southward displacement of the Shan-Thai block. Our results link the tectonic activity of the EHS to the lateral extrusion of the southeastern margin of the Tibetan Plateau, providing a new perspective on the evolution of this region since the late Eocene.
•The Mangkang area in the southeast of Qiangtang terrane was located at a paleolatitude of 20.5±0.9° N during the Late Eocene.•The Eastern Himalayan Syntaxis was formed after 35 Ma, when Eurasia was penetrated by ∼600 km by northward-moving India.•The Shan-Thai block underwent an insignificant degree of southward displacement.
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