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The juvenile-to-adult phase change with first flowering as the indicator plays a crucial role in the lifecycle of fruit trees. However, the molecular mechanisms underlying phase change in fruit trees remain largely unknown. Shikimic acid (ShA) pathway is a main metabolic pathway closely related to the synthesis of hormones and many important secondary metabolites participating in plant phase change. So, whether ShA regulates phase change in plants is worth clarifying. Here, the distinct morphological characteristics and the underlying mechanisms of phase change in jujube (Ziziphus jujuba Mill.), an important fruit tree native to China with nutritious fruit and outstanding tolerance abiotic stresses, were clarified. A combined transcriptome and metabolome analysis found that ShA is positively involved in jujube ('Yuhong' x 'Xing 16') phase change. The genes in the upstream of ShA synthesis pathway (ZjDAHPS, ZjDHQS and ZjSDH), the contents of ShA and the downstream secondary metabolites like phenols were significantly upregulated in the phase change period. Further, the treatment of spraying exogenous ShA verified that ShA at a very low concentration (60 mg $ L-1) can substantially speed up the phase change and flowering of jujube and other tested plants including Arabidopsis, tomato and wheat. The exogenous ShA (60 mg $ L-1) treatment in jujube seedlings could increase the accumulation of endogenous ShA, enhance leaf photosynthesis and the synthesis of phenols especially flavonoids and phenolic acids, and promote the expression of genes (ZjCOs, ZjNFYs and ZjPHYs) involved in flowering pathway. Basing on above results, we put forward a propose for the underlying mechanism of ShA regulating phase change, and a hypothesis that ShA could be considered a phytohormone-like substance because it is endogenous, ubiquitous, movable and highly efficient at very low concentrations. This study highlights the critical role of ShA in plant phase change and its phytohormone-like properties. [ABSTRACT FROM AUTHOR]

Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However, the immaturity of its stable transformation system and its low transformation efficiency limit gene function research on non-heading Chinese cabbage. Agrobacterium rhizogenes-mediated (ARM) transgenic technology is a rapid and effective transformation method that has not yet been established for non-heading Chinese cabbage plants. Here, we optimized conventional ARM approaches (one-step and two-step transformation methods) suitable for living non-heading Chinese cabbage plants in nonsterile environments. Transgenic roots in composite non-heading Chinese cabbage plants were identified using phenotypic detection, fluorescence observation, and PCR analysis. The transformation efficiency of a two-step method on four five-day-old non-heading Chinese cabbage seedlings (Suzhouqing, Huangmeigui, Wuyueman, and Sijiu Caixin) was 43.33%e51.09%, whereas using the stout hypocotyl resulted in a transformation efficiency of 54.88% for the 30-day-old Sijiu Caixin. The one-step method outperformed the two-step method; the transformation efficiency of different varieties was above 60%, and both methods can be used to obtain transgenic roots for functional studies within one month. Finally, optimized ARM transformation methods can easily, quickly, and effectively produce composite non-heading Chinese cabbage plants with transgenic roots, providing a reliable foundation for gene function research and non-heading Chinese cabbage genetic improvement breeding. [ABSTRACT FROM AUTHOR]

With the theoretical and technological developments related to cratonic strike-slip faults, the Shuntuoguole Low Uplift in the Tarim Basin has attracted considerable attention recently. Affected by multistage tectonic movements, the strike-slip faults have controlled the distribution of hydrocarbon resources owing to the special fault characteristics and fault-related structures. In contrast, the kinematics and formation mechanism of strike-slip faults in buried sedimentary basins are difficult to investigate, limiting the discussion of these faults and hydrocarbon accumulation. In this study, we identified the characteristics of massive sigmoidal tension gashes (STGs) that formed in the Shunnan area of the Tarim Basin. High-resolution three-dimensional seismic data and attribute analyses were used to investigate their geometric and kinematic characteristics. Then, the stress state of each point of the STGs was calculated using seismic curvature attributes. Finally, the formation mechanism of the STGs and their roles in controlling hydrocarbon migration and accumulation were discussed. The results suggest that: (1) the STGs developed in the Shunnan area have a wide distribution, with a tensile fault arranged in an en échelon pattern, showing an S-shaped bending. These STGs formed in multiple stages, and differential rotation occurred along the direction of strike-slip stress during formation. (2) Near the principal displacement zone of the strike-slip faults, the stress value of the STGs was higher, gradually decreasing at both ends. The shallow layer deformation was greater than the deep layer deformation. (3) STGs are critical for connecting source rocks, migrating oil and gas, sealing horizontally, and developing efficient reservoirs. This study not only provides seismic evidence for the formation and evolution of super large STGs, but also provides certain guidance for oil and gas exploration in this area. [ABSTRACT FROM AUTHOR]

The reliability analysis of vertically integrated protection devices is crucial for designing International Electrotechnical Commission (IEC) 61850-based substations. This paper presents the hardware architecture of a four-inone vertically integrated device and the information transmission path of each function based on the functional information transmission chain of protection devices, measurement and control devices, merging units, and intelligent terminals. Additionally, a reliability analysis model of the protection device and its protection system is constructed using the fault tree analysis method while considering the characteristics of each module of the vertically integrated device. The stability probability of the protection system in each state is analyzed by combining the state-transfer equations of line and busbar protection with a Markov chain. Finally, the failure rate and availability of the protection device and its protection system are calculated under different ambient temperatures using a 110 kV intelligent substation as an example. The sensitivity of each device module is analyzed. [ABSTRACT FROM AUTHOR]

The progress of research and forecast techniques for tropical cyclone (TC) unusual tracks (UTs) in recent years is reviewed. A major research focus has been understanding which processes contribute to the evolution of the TC and steering flow over time, especially the reasons for the sharp changes in TC motion over a short period of time. When TCs are located in the vicinity of monsoon gyres, TC track forecast become more difficult to forecast due to the complex interaction between the TCs and the gyres. Moreover, the convection and latent heat can also feed back into the synoptic-scale features and in turn modify the steering flow. In this report, two cases with UTs are examined, along with an assessment of numerical model forecasts. Advances in numerical modelling and in particular the development of ensemble forecasting systems have proved beneficial in the prediction of such TCs. There are still great challenges in operational track forecasts and warnings, such as the initial TC track forecast, which is based on a poor pre-genesis analysis, TC track forecasts during interaction between two or more TCs and track predictions after landfall. Recently, artificial intelligence (AI) methods such as machine learning or deep learning have been widely applied in the field of TC forecasting. For TC track forecasting, a more effective method of center location is obtained by combining data from various sources and fully exploring the potential of AI, which provides more possibilities for improving TC prediction. [ABSTRACT FROM AUTHOR]

Large earthquakes can cause both casualties and economic losses, but they also provide invaluable opportunities for earthquake scientific research. Geofluids, due to their wide distribution, sensitive response to underground conditions, and ease of observation, are widely applied in field investigations after earthquakes. Analyzing the origin of fluids, energy transfer processes, temperature/pressure conditions, and the spatial-temporal evolution of geofluids can provide valuable information concerning the mechanism of earthquake precursor anomalies, short-term prediction methods, identification of the seismogenic faults, determination of earthquake risk, and the environmental impact of post-earthquake fluids. This article details post-earthquake scientific expeditions and research on fluid geochemistry in China and abroad, aimed at providing ideas and guidance for future scientific expedition work and geochemistry-related earthquake studies. [ABSTRACT FROM AUTHOR]

Shale samples from the Ordovician Wulalike Formation at the western margin of the Ordos Basin are studied to define the types, microstructures and connectivity of pores as well as the relationships between the pore structures and gas content of the samples by using experimental techniques such as high-resolution field emission scanning electron microscopy (FESEM), mercury injection capillary pressure (MICP), low-temperature nitrogen adsorption (LTNA), CO2 adsorption, and focused ion beam scanning electron microscopy (FIB-SEM). The results show that the shale has 10 different lithofacies, typical mixed sedimentary characteristics, and poorly developed pores. The reservoir space mainly consists of intercrystalline pores, dissolution pores, intergranular pores, and micro-fissures, with organic pores occasionally visible. The pore size is mostly within 0.4e250 nm range but dominated by micropores and mesopores less than 20 nm, with pore numbers peaking at pore sizes of 0.5 nm, 0.6 nm, 0.82 nm, 3 nm, and 10 nm, respectively. The pores are poorly connected and macropores are rarely seen, which may explain the low porosity and low permeability of the samples. Samples with high content of organic matter and felsic minerals are potential reservoirs for oil and gas with their favorable physical properties and high connectivity. The pores less than 5 nm contribute significantly to the specific surface area and serve as important storage space for adsorbed gas. [ABSTRACT FROM AUTHOR]

Exposing waxy oils to an electric field may significantly improve their cold flowability. Our previous study has shown that interfacial polarization, i.e., charged particle accumulation on the wax particle surface, is the primary mechanism of the electrorheological behavior of waxy oils. However, the way that charged particles interact with wax particles under an electric field remains unknown. In this study, we found no viscosity and impedance change for two waxy crude oils after their exposure to a high-voltage electric field. However, the yield stresses were reduced obviously. We thus proposed that the collision of colloidal particles such as resins and asphaltenes with the wax particles could be an essential mechanism that the wax particle structure was weakened. To verify this hypothesis, a series of ad hoc experiments were carried out, i.e., by performing electrorheological tests on model waxy oils containing additives removable under an electric field, including electrically-neutral colloidal particles (Fe3O4), charged colloidal particles (resins), and oil-soluble electrolyte (C22H14CoO4), respectively, and demonstrated that upon application of a high-voltage electric field, charged particles in a waxy oil may move and thus collide with wax particles, and consequently adhere to the wax particle surface. The particle collision results in damage to the wax particle network, and the electrostatic repulsion arising from the adhesion of the charged particle on the wax particle diminishes attraction between wax particles. This study clarifies the process of interfacial polarization. [ABSTRACT FROM AUTHOR]

Based on the high positioning accuracy, low cost and low-power consumption, the ultra-wide-band (UWB) is an ideal solution for indoor unmanned aerial vehicle (UAV) localization and navigation. However, the UWB signals are easy to be blocked or reflected by obstacles such as walls and furniture. A resilient tightly-coupled inertial navigation system (INS)/UWB integration is proposed and implemented for indoor UAV navigation in this paper. A factor graph optimization (FGO) method enhanced by resilient stochastic model is established to cope with the indoor challenging scenarios. To deal with the impact of UWB non-line-of-sight (NLOS) signals and noise uncertainty, the conventional neural net-works (CNNs) are introduced into the stochastic modelling to improve the resilience and reliability of the integration. Based on the status that the UWB features are limited, a 'two-phase' CNNs structure was designed and implemented: one for signal classification and the other one for measurement noise prediction. The proposed resilient FGO method is tested on flighting UAV platform under actual indoor challenging scenario. Compared to classical FGO method, the overall positioning errors can be decreased from about 0.60 m to centimeter-level under signal block and reflection scenarios. The superiority of resilient FGO which effectively verified in constrained environment is pretty important for positioning accuracy and integrity for indoor navigation task. [ABSTRACT FROM AUTHOR]

Gradiently denitrated gun propellant (GDGP) prepared by a "gradient denitration" strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant. Currently, the preparation of GDGP employed a tedious two-step method involving organic solvents, which hinders the large-scale preparation of GDGP. In this paper, GDGP was successfully prepared via a novelty and environmentally friendly one-step method. The obtained samples were characterized by FT-IR, Raman, SEM and XPS. The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant, with a well-preserved nitrocellulose structure. The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance, as confirmed by oxygen bomb and closed bomb test. At the same time, the effects of different solvents on the component loss of propellant were compared. The result showed that water caused the least component loss. Finally, the stability of GDGP was confirmed by methyl-violet test. This work not only provided environmentally friendly, simple and economic preparation of GDGP, but also confirmed the stability of GDGP prepared by this method. [ABSTRACT FROM AUTHOR]

Using commercially available raw materials, novel pyrimidine-based energetic compounds were synthesized, namely N-(7-oxo-6,7-dihydro-[1,2,5]oxadiazolo[3,4-d]pyrimidin-5-yl)nitramide (1), 2,4,6-triamino-5-nitropyrimidin-1-ium nitrate (2), and 4,6-diamino-5-nitro-2-oxo-2,3-dihydropyrimidin-1-ium nitrate (3). They were fully characterized using NMR (¹H and 13C), IR spectroscopy, and elemental analysis. The crystal structures of compounds 1 and 3 were determined using single-crystal X-ray diffraction. The decomposition temperatures of compounds 1-3 were measured to be 190.2 °C, 156.8 °C, and 234.6 °C, respectively. Their densities were tested to be 1.84, 1.85 g cm-3, and 1.81 g cm-3, respectively. They exhibited desirable insensitive properties, with impact sensitivity ≥15 J and friction sensitivity >360 N. In addition, the detonation performances of compounds 1-3 were calculated with detonation pressure of 26.9, 29.6 GPa, and 26.0 GPa, respectively; detonation velocity of 8089, 8644 m s-1, and 7996 m s-1, respectively). Simple synthetic processes and high performance make them potential candidates for low-sensitivity energetic materials. [ABSTRACT FROM AUTHOR]

The investigation of seismic wave propagation across discontinuous rock masses is of great importance for solving earthquake engineering problems. Although the parameters affecting the propagation of wave on the structural surface have been known to some extent, the influence of cohesion, inclination, and stiffness on the propagation of wave when passing through structural plane still needs further study. In the study of the incident wave simulation, we implemented FLAC3D to build the model with interface to measure the energy loss due to different parameters in the interface. The effect of cohesion, normal and shear stiffness, and dipping angle on characteristics of energy dissipation were investigated. Numerical results indicated that the cohesion as the adhesion of the material is playing an important role in energy dissipation. The normal and shear stiffness is not as obvious as what cohesion does, especially when they are at very low value. In addition, an increase in angle will bring about a decrease in the transmission coefficient and a decrease followed by an increase in the reflection coefficient. [ABSTRACT FROM AUTHOR]

The impaired osteogenic ability and excessive accumulation of reactive oxygen species (ROS) under osteoporosis severely weaken repair performance of biomimetic bone grafts. Currently, biomimetic bone grafts, capable of highly simulating bone hierarchy, could remarkably promote bone regeneration without systemic disease. Decorating biomimetic bone grafts with bioactivities without compromising hierarchical biomimicry stands as a feasible approach to treat the osteoporotic bone defect. Herein, through mineralizing decellularized collagen lamellae via strontium (Sr)- amorphous calcium phosphate and further modifying with tannic acid (TA), TA modified Sr-doped biomimetic bone lamellae was engineered. The physicochemical properties, ROS scavenging capacity and pro-osteogenic effect on osteoporotic bone marrow mesenchymal stem cells of construct were systemically evaluated. The results showed that TA and Sr can be successfully decorated without impairing the nanoand micro-architecture of biomimetic bone lamellae. The construct not only exhibited a potent and long-standing performance to eliminate ROS, but also effectively fostered the proliferation and osteogenic differentiation of osteoporotic bone marrow mesenchymal stem cells under oxidative stress environment. After implantation in the critical-sized bone defect of osteoporotic rat, it potently facilitated bone regeneration via synergistically activating PI3K/AKT signaling pathway. Hence, this construct is projected to be candidate for further engineering biomimetic bone grafts with more complicated hierarchy for accelerated healing of the osteoporotic bone defect. [ABSTRACT FROM AUTHOR]

This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading. The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading. According to the Hopkinson's scaling law, three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study. The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation (DIC) method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen. In addition, a finite element model was developed for the modification of the scaling law. The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes. The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided. [ABSTRACT FROM AUTHOR]

Alternate-temperature loading can cause cyclic thermal stress; therefore complex artificial fracture networks are formed in hot dry rock owing to thermal expansion and contraction under alternating thermal loading. In this study, the heat recovery potential of hot dry rock with a complex fracture network under alternating temperature loading was simulated numerically based on the hydrothermal coupling algorithm and compared with that of hot dry rock with a single fracture. The results show that the complex fractures formed under alternate thermal loading have better heat recovery performance than a single fracture, and the heat recovery performance of a complex fracture network is closely related to the intersection angle of fractures in the network. The temperature at the fracture outlet increases with an increase in the intersection angle between the branch fractures and the main fracture. At the angle of 30 between the branch fractures and main fracture, the average temperatures at the fracture outlet were 0.031% and 0.025% higher than those at the angles of 90 and 60, respectively. Simultaneously with the water-injection, the temperature in the branch fractures gradually increased with an increase in the angle of the crossing fractures. When the angle between the branch and main fractures was 90, the temperature fields on the two sides of the branch fracture were symmetrical. When the angle was 60 or 30, the temperature fields on the two sides of the branch fracture were asymmetrical. The results of this study provide theoretical and technical support for the extraction of deep geothermal energy. [ABSTRACT FROM AUTHOR]