EphB2 Deficiency Induces Depression-Like Behaviors and Memory Impairment: Involvement of NMDA 2B Receptor Dependent Signaling

Receptor tyrosine kinase EphB2 mediates development of the neurogenic niche of excitatory neurons, suggesting the possibility that its inactivation plays a role in neuropsychiatric disorders including depression and memory impairment. While N-methyl-D-aspartate (NMDA) receptor is involved in regulating memory formation and neurogenesis in adult animal, it remains unclear how NMDA receptor subtypes mediate depression and cognitive deficits caused by EphB2 loss. The present study shows that EphB2 inactivation results in depression-like behaviors, memory impairment and defects of adult hippocampal neurogenesis. Compared to wild-type littermates, EphB2 KO mice exhibited depression-like behavior and deficits in spatial memory and cognition in forced swimming, tail suspension, Morris water maze, object recognition test and object location test. These behavioral abnormalities were accompanied by substantial decreases in the number of BrdU+ progenitor neurons, phosphorylation of cAMP-response element binding protein (pCREB) and brain derived neurotrophic factor (BDNF), and increased NMDA receptor 2B (NR2B) expression. These molecular, cellular and behavioral alterations induced by EphB2 inactivation were reversed by NR2B antagonist Ro25-6981, suggesting that EphB2 functions to prevent the progression of depression-like behavior and memory impairment by downregulating NR2B. Our findings highlight that NR2B is responsible for EphB2-dependent behavioral and morphological changes. EphB2 may thus be as an important candidate target for treating psychiatric and cognitive disorders

Durability Performance of Basalt Fiber-Reinforced Concrete Subjected to Sulfate–Magnesium Combined Attack

In salt lake areas, cast-in situ concrete structures are subjected to long-term corrosion by sulfate and magnesium ions. The properties of concrete can be improved by adding materials like basalt fiber (BF). To investigate the degradation process and mechanism of cast-in situ concrete with premixed BF under the dual corrosion of sulfate and magnesium salts, concrete with a content of BF ranging from 0 to 0.5% was prepared. Specimens were subjected to different internal and external corrosion conditions and immersed for 180 days. Dimension, mass, and appearance changes at different immersion times were recorded. The compressive and flexural strength of the specimens were tested and continually observed throughout the immersion time. Mineral and microstructural changes at different immersion times were determined by the XRD, TG, and SEM analysis methods. Results indicated that external sulfate–internal magnesium combined attack had a significant negative effect on the early strength. The compressive and flexural strength of the corroded specimens decreased by 17.2% and 14.1%, respectively, compared to the control group at 28 days. The premixed magnesium ions caused the decomposition of the C-S-H gel, resulting in severe spalling and lower mechanical properties after immersing for a long time. As the BF can inhibit crack development, the properties of the concrete premixed with BF were improved. Specimens exhibited superior performance at a BF content of 0.5%, resulting in a 16.2% increase in flexural strength. This paper serves as a valuable reference for the application of basalt fiber-reinforced concrete under the challenging conditions of sulfate–magnesium combined attack

Degradation Mechanism of Concrete Subjected to External Sulfate Attack: Comparison of Different Curing Conditions

Sulfate induced degradation of concrete brings great damage to concrete structures in saline or offshore areas. The degradation mechanism of cast-in-situ concrete still remains unclear. This paper investigates the degradation process and corresponding mechanism of cast-in-situ concrete when immersed in sulfate-rich corrosive environments. Concrete samples with different curing conditions were prepared and immersed in sulfate solutions for 12 months to simulate the corrosion of precast and cast-in-situ concrete structures, respectively. Tests regarding the changes of physical, chemical, and mechanical properties of concrete samples were conducted and recorded continuously during the immersion. Micro-structural and mineral methods were performed to analyze the changes of concrete samples after immersion. Results indicate that the corrosion process of cast-in-situ concrete is much faster than the degradation of precast concrete. Chemical attack is the main cause of degradation for both precast and cast-in-situ concrete. Concrete in the environment with higher sulfate concentration suffers more severe degradation. The water/cement ratio has a significant influence on the durability of concrete. A lower water/cement ratio results in obviously better resistance against sulfate attack for both precast and cast-in-situ concrete

A potential way for improving the dispersivity and mechanical properties of dispersive soil using calcined coal gangue

This paper investigated the improvement behaviors on dispersivity, water stability and mechanical properties of dispersive soil by calcined coal gangue (CCG) at 700 °C, and analyzed the modification mechanism. Dispersive soil specimens with different content of CCG (varying from 1 % to 10 %) were prepared and cured for 0–28 days. The dispersivity of the soil was determined by three different dispersivity determination tests. The tensile strength and compressive strength of the dispersive soil were determined by mechanical property tests. SEM, EDS, TG and XRD analytical methods were employed to reveal microstructure and mineral changes during modification. The results of the study show that the admixture of CCG and the prolongation of curing time contributed favorably to suppressing the dispersivity of the soil and enhancing the water stability, the compressive strength and tensile strength of the dispersive soil. With the increasing of CCG content and the prolongation of curing time, the dispersive soil gradually transforms into non-dispersive soil. Microstructural and mineral analysis indicate that CCG has pozzolanic activity, and the production of pozzolanic reaction products significantly increase the friction and cohesion among soil particles. The results show that the utilization of CCG as an admixture to improve the dispersive soil not only solves the disposal problem of waste gangue, but also optimizes the undesirable characteristics of the dispersive soil. And the modification effect of CCG on dispersive soil in practical engineering is confirmed by validation test

Laser In Situ U–Pb Isotope Dating of Carbonate Rocks in Weijia Guyot in the Western Pacific Ocean and Its Geological Significance

Shallow-water carbonate rocks constitute a crucial component of large guyots, arising in distinct environments and harboring valuable insights into the evolutionary stages of seamount islands as well as the tectonic conditions of the underlying oceanic plate. Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) was used to conduct in situ U–Pb isotope dating of carbonate minerals with low uranium content collected from Weijia Guyot. This dating approach yielded crucial evidence for the vertical development of the seamount. Our study indicates that shallow-water carbonate rocks in Weijia Guyot had a temporal range between 91 My and 137 My. The carbonate rocks underwent two growth phases, Hauterivian to Barremian and Cenomanian to Turonian, with a hiatus of approximately 20 My. Since the Hauterivian age, the shield volcano of Weijia Guyot is essentially complete, with its seamount top exposed at or near sea level and receiving its first stage of shallow-water carbonate sedimentation. Based on the dating of both shallow-water carbonate rocks and hawaiite within the Weijia Guyot, it is inferred that approximately 10 My elapsed from shield-building volcanism to late alkalic volcanism. During the Turonian age, the main reason for the second phase of shallow-water carbonate rocks in the seamounts was the regional tectonic uplift triggered by the drift of the Weijia Guyot along with the Pacific Plate toward the Society hotspot

Laboratory Model Test to Explore the Bearing Mechanism of Composite Foundation in the Loess Area

Pile composite foundation can make good use of the bearing capacity of the soil and pile, which is widely used in the Chinese northwest loess area. However, the theory of pile composite foundation is far from sufficient, hindering its long-term development. Aiming at this problem, a laboratory model test of pile composite foundation in the loess area was conducted to explore the common working mechanism and variations of each bearing stage. Besides, the settlement of the single pile composite foundation was calculated by using the modified tangent modulus method, and the result was compared with the experimental data. The main results of this paper are as follows: Both in the single pile and single pile composite foundation, loading-settlement curves showed a trend of “elastic to elastoplastic to plastic,” accompanied by the appearance of plummeting point. Influenced by the pile group effect, the loading-settlement curve of the group pile composite foundation showed a slow-varying trend without an obvious breakdown point. Pile axis stress increased with the growth of upper load. At the beginning of loading, the pile axis stress indicated such a distribution that stress on both ends of the pile was larger than that in the middle of the pile. When reaching a certain load, the location of the biggest pile axis stress transferred to the pile top, and the pile axis stress decreased gradually as the pile became deep. The side friction resistance in the static load test of the single pile was always positive, whereas in the composite foundation of a single pile and a group of piles, negative side resistance appeared in the upper side of the neutral point. Pile-soil stress ratio in the depth of 12 cm changed with the upper load. The outcome calculated by the modified tangent modulus method had a relatively better consistency with experimental data if the upper load was not too large

Influence of Ca2+ on Early Degradation of Cast-In-Situ Mortar Induced by Sulfate-Magnesium Multiple Combined Attack

Early degradation of cast-in-situ concrete induced by multiple internal–external sulfate combined attacks significantly affects the development of concrete strength. An experimental study regarding the effects of Ca2+ on the early degradation of cast-in-situ mortars subjected to internal–external sulfate and magnesium combined attacks is investigated in this paper. In particular, a specific method for accurately simulating the degradation of cast-in-situ structures was proposed in this experiment. Physical properties (including weight, size changes, and porosity), mechanical properties (including flexural strength and compressive strength), sulfate concentration, and microstructural properties were monitored during 28 days of immersion. The results show that an internal sulfate and magnesium combined attack (ISA-IMA) obviously retards the development of early strength and accelerates the degradation induced by external sulfate attack (ESA). The diffusion path of sulfate ions from outside is blocked by flake-shaped magnesium hydrates, delaying the penetration of external sulfate attacks. However, it is far from neutralizing the strength loss induced by an internal magnesium attack (IMA) at an early age. Premixed excessive Ca2+ would improve the strength development and pore structure of concrete or mortar, enhancing durability against corrosive conditions

Changing of mechanical property and bearing capacity of strongly chlorine saline soil under freeze-thaw cycles

Abstract Freeze-thaw cycles and compactness are two critical factors that significantly affect the engineering properties and safety of building foundations, especially in seasonally frozen regions. This paper investigated the effects of freeze-thaw cycles on the shear strength of naturally strongly chlorine saline soil with the compactness of 85%, 90% and 95%. Three soil samples with different compactness were made. Size and mass changes were measured and recorded during freeze-thaw cycles. Shear strength under different vertical pressures was determined by direct shear tests, and the cohesion and friction angle were measured and discussed. Microstructure characteristic changes of saline soil samples were observed using scanning electron microscopy under different freeze-thaw cycles. Furthermore, numerical software was used to calculate the subsoil-bearing capacity and settlement of the electric tower foundation in the Qarhan Salt Lake region under different freeze-thaw cycles. Results show that the low-density soil shows thaw settlement deformation, but the high-density soil shows frost-heaving deformation with the increase in freeze-thaw cycles. The shear strength of the soil samples first increases and then decreases with the increase in freeze-thaw cycles. After 30 freeze-thaw cycles, the friction angle of soil samples is 28.3%, 29.2% and 29.6% lower than the soil samples without freeze-thaw cycle, the cohesion of soil samples is 71.4%, 60.1% and 54.4% lower than the samples without freeze-thaw cycle, and the cohesion and friction angle of soil samples with different compactness are close to each other. Microstructural changes indicate that the freeze-thaw cycle leads to the breakage of coarse particles and the aggregation of fine particles. Correspondingly, the structure type of soil changes from a granular stacked structure to a cemented-aggregated system. Besides, the quality loss of soil samples is at about 2% during the freeze-thaw cycles. Results suggest that there may be an optimal compactness between 90 and 95%, on the premise of meeting the design requirements and economic benefits. This study can provide theoretical guidance for foundation engineering constructions in seasonally frozen regions

Research on current-mode damping impedance interface model based on adaptive impedance matching

With the development and progress of new energy electricity generation technology, a detailed study and test is required on new energy power generation equipment and micro-network system. As of the advantage of both numerical simulation and physical simulation, power connection type digital physical mixed simulation system could accomplish such research and tests. The simulation interface is the key to realise hybrid simulation. This paper proposes a current-mode damping impedance interface model based on adaptive impedance matching. The model is analysed from the interface stability, the accuracy and the dynamic response ability according to the structure of the interface model. Both theoretical analysis and simulation results show that current-mode damping impedance interface model based on adaptive impedance has high stability and accuracy, and also good dynamic response capability

Carbon Emission Evaluation Method and Comparison Study of Transformer Substations Using Different Data Sources

The construction of transformer substations in transmission lines is a systematic, technical, and complex project with the need for numerous materials and resources. Under the development of the green economy, the requirements for energy conservation and carbon reduction have improved; hence, an assessment of carbon emissions in transformer substations is urgently needed. A calculation method was proposed in the present study to analyze the carbon emissions of transformer substations with different kinds of data sources, which were collected from several practical projects in the west-to-east power transmission project. In this study, a detailed comparison and discussion regarding the differences in carbon emissions of 750 kV transformer substations caused by hydrology, geology, engineering quantity, and other factors were conducted. The mean value, standard deviation, and 90% confidence interval of carbon emissions were obtained by Monte Carlo simulation through MATLAB. Results show that the total carbon emissions of the selected 750 kV transformer substations are between [56,000, 68,000] t CO2 eq. Construction engineering accounts for more than 50% of carbon emissions, followed by installation engineering and additional services. In terms of input items, electricity distribution buildings contribute more than 39% of total carbon emissions, followed by cable/earthing systems, which account for 14% of total carbon emissions. Gas insulated switchgear (GIS) and air insulated switchgear (AIS) could adopt different types of equipment foundations, and GIS equipment foundations would generate fewer carbon emissions due to the smaller land area and input materials. This study can provide experience and reference for similar projects and further guide the substation carbon emission reduction work