Search Results (223)

To address the poor thermal performance and low output efficiency of conventional solid-state microchip lasers, this study proposes and implements a bonded Nd:YAG/Cr⁴⁺:YAG laser based on fiber splitter pumping. Experimental results demonstrate that at a 4.02 mJ pump pulse energy and a 100 Hz repetition rate, the system achieves four linearly polarized output beams with an average pulse energy of 0.964 mJ, a repetition rate of 100 Hz, and an optical-to-optical conversion efficiency of 23.98%. The energy distribution ratios for the upper-left, lower-left, upper-right, and lower-right beams are 22.61%, 24.46%, 25.50%, and 27.43%, with pulse widths of 2.184 ns, 2.193 ns, 2.205 ns, and 2.211 ns, respectively. As the optical axis distance increases, the far-field spot pattern transitions from a single circular profile to four fully separated spots, where the lower-right beam exhibits beam quality factors of M_x² = 1.181 and M_y² = 1.289. Simulations at a 293.15 K coolant temperature and a 4.02 mJ pump energy reveal that split pumping reduces the volume-averaged temperature rise in Nd:YAG by 28.81% compared to single-beam pumping (2.57 K vs. 3.61 K), decreases the peak temperature rise by 66.15% (6.97 K vs. 20.59 K), and suppresses peak-to-peak temperature variation by 78.6% (1.34 K vs. 6.26 K). Compared with existing multi-beam generation methods, the fiber splitter approach offers integrated advantages—including compact size, low cost, high energy utilization, superior beam quality, and elevated damage thresholds—and thus shows promising potential for automotive multi-point ignition, multi-beam single-photon counting LiDAR, and laser-induced breakdown spectroscopy (LIBS) online analysis. Full article

In the operation of enhanced geothermal systems (EGSs), complex physical and chemical coupling processes, which are crucial for the efficient exploitation of geothermal energy, are involved. In situ studies of multi-fracture hot dry rocks (HDRs) face significant challenges, leading to a shortage of experimental data for verifying numerical simulations and supporting experimental techniques. In this paper, a multi-field coupling experimental simulation technique was designed for a multi-fracture geothermal reservoir. This technique enables the experimental investigation of the effects of fracture and reservoir characteristics, working fluid parameters, and wellbore arrangement on the multi-field coupling transport mechanism inside geothermal reservoirs during EGS operation. In addition, the practicability and reliability of the experimental technique were proved via a two-dimensional multi-fracture model. The experimental technique addresses a research gap in studying multi-fracture geothermal reservoirs and holds potential to promote substantial progress in geothermal resource exploitation. Full article

The orderly progression of the cell division process is crucial for the morphogenesis of pathogens and the process of infecting hosts. However, there is currently no relevant research on cell division in the pathogen Peronophythora litchii. First, we verified that treatment with cell division inhibitors would have an adverse effect on the growth, development, and pathogenicity of P. litchii. Subsequently, through homology-based sequence alignment and functional domain prediction analyses, we identified PlTem1, a key small GTPase regulating cell division. Compared with the wild-type strain Shs3, the mutant strain ΔPltem1 exhibited significant defects in mycelial growth, sporangia and zoospore generation, and virulence. To explore the pathogenic mechanism of PlTem1, screening and identification of interacting proteins were carried out. The comprehensive results show that there is an interaction between Tem1 and multiple autophagy-related proteins, suggesting that PlTem1 serves as an important bridge between autophagy and cell division in P. litchii. Full article

Since 2020, the BDS-3 has been providing real-time corrections via the B2b signal, enabling users in China and its neighboring regions to achieve kinematic positioning accuracy at the decimeter level. The rapid geometric changes of Low-Earth-Orbit (LEO) satellites facilitate the rapid resolution of phase ambiguities and accelerate the convergence of Precise Point Positioning (PPP). Therefore, this study proposes an LEO-enhanced BDS-3 PPP-B2b positioning model. Firstly, a novel BDS-3 PPP model accounting for satellite clock bias characteristics is proposed, and experimental validation confirms its efficacy. Subsequently, an LEO-enhanced BDS-3 PPP model is developed. Finally, the positioning performance is rigorously evaluated using combined LEO simulation observations and BDS-3 observations. The results indicate that, compared with the traditional PPP model, the new model yields an average convergence time of 25.1 min for experiments where the convergence criterion is jointly satisfied, representing a 35.6% improvement in convergence speed, while maintaining the same positioning accuracy after convergence. When augmented with LEO satellites, the convergence time of the BDS-3 PPP-B2b solution is reduced to less than 2 min. Furthermore, when more than three LEO satellites are available, the mean convergence time is shortened to within 1 min. Full article

Glutamate is an excitatory neurotransmitter in the central nervous system (CNS) that mediates synaptic transmission. However, glutamate homeostasis among neural cells is broken in cerebral ischemia. Excessive glutamate triggers N-methyl-d-aspartate receptors (NMDARs) in postsynaptic neurons, leading to intracellular calcium (Ca²⁺) overload and excitoneurotoxicity. At this moment, L-lactate may affect NMDARs and play a protective role in cerebral ischemia. This work proposes that L-lactate regulates glutamate signaling among neural cells. But, dysregulation of L-lactate in glutamate signaling cascades contributes to glutamate excitotoxicity in cerebral ischemia. In detail, L-lactate regulates the glutamine(Gln)-glutamate cycle between astrocytes and presynaptic neurons, which triggers the astroglial L-lactate-sensitive receptor (LLR)-cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway, coordinating astroglial glutamate uptake and neuronal glutamate transmission. L-lactate mediates glutamate signaling and synaptic transmission among neural cells. In addition, L-lactate promotes the function of mitochondrial calcium uniporter complex (MCUC), which quickly depletes intracellular Ca²⁺ in postsynaptic neurons. In addition, L-lactate can promote the conversion of microglia from the pro-inflammatory (M1) to anti-inflammatory (M2) phenotype. Therefore, regulation of L-lactate in glutamate signaling in the CNS might become a preventive target for cerebral ischemia. Full article

Background: canine distemper (CD) is a highly contagious and fatal disease caused by canine distemper virus (CDV), posing a significant threat to carnivores. New CDV strain circulation and multi-species infection may lead to the potential dilemma of safety concern and insufficient efficacy of the commercial modified live vaccines. Safe and effective vaccines for canine and wildlife prevention of CD need to be continuously updated and developed. Methods: we developed two DNA vaccines, p17F-LNP and p17H-LNP, encoding the fusion protein (F) or hemagglutinin protein (H) of a field CDV strain (HLJ17) and encapsulated in lipid nanoparticles (LNPs). Serum neutralizing antibody (NAb) was evaluated via neutralization tests, and mouse serum cytokine detection were evaluated via ELISA. Results: immunization of p17F-LNP and p17H-LNP monovalent or bivalent were safe, and induced robust CDV NAb and cytokine responses in mice. LNP encapsulation improved immune responses compared to naked DNA formulation, and the bivalent formulation of p17F-LNP and p17H-LNP (p17F/H-LNP) exhibited synergistic effects with a high level of immune responses. Moreover, two doses of p17F/H-LNP induced long-lasting CDV NAb for over 300 days in dogs, and prime and boost NAb responses in foxes and raccoon dogs. Conclusions: the preliminary findings provided here warrant further development of the p17F/H-LNP vaccine for animal targets against CDV infection. Full article

Induction quenching is critical for high-strength bulb flat steel, yet the influence of the heating temperature on mechanical property uniformity across sections remains underexplored. This study systematically investigates the effect of the induction heating temperature on mechanical property uniformity, prior austenite grain size, and microstructural evolution in bulb flat steel. Experimental results reveal that increasing the induction heating temperature from 845 °C to 1045 °C induces distinct mechanical responses: the yield strength disparity between the bulb and flat sections decreases by 93% (from 94 MPa), significantly improving sectional uniformity. Microstructural analysis indicates that prior austenite grain size coarsens with higher induction heating temperatures. The quenched microstructure comprises martensite and bainite in the bulb core, while the flat section is entirely martensitic. The yield strength differential between the bulb and flat sections is governed by temperature-dependent strengthening mechanisms: dislocation strengthening dominates at 845 °C~985 °C, with the bulb region exhibiting higher strength due to increased dislocation density, while grain boundary strengthening prevails at 1045 °C, where the flat region benefits from finer grains. Full article

Accurate identification of mattic epipedon degradation is critically important for addressing ecological issues such as the weakening of alpine grassland carbon sink capacity and reduced soil and water conservation. However, efficient and rapid methods for its detection remain limited. This study aimed to clarify the hyperspectral response mechanisms of mattic epipedon degradation and, based on hyperspectral technology, to construct models for identifying degraded mattic epipedon and screen preprocessing methods suitable for different moisture conditions. The results showed the following: (1) The XGBoost model with preprocessing using multiplicative scatter correction combined with second derivative transformation (MSC+SD) performed best, achieving an identification accuracy and Kappa coefficient of 0.85 and 0.82, respectively. The characteristic bands were concentrated in the visible light range (446–450 nm) and short-wave infrared range (2134 nm, 2267–2269 nm), which are closely related to the spectral responses of organic carbon and mineral components. (2) Spectral reflectance was significantly negatively correlated with moisture content, and model accuracy decreased as moisture content increased. (3) After correction using the EPO algorithm, the model accuracy for the high-moisture group improved by 13.2–16.7%, whereas that for the low-moisture group (<15%) decreased by 7.5%, verifying 15% moisture content as the critical threshold for water interference. This study elucidated the impact mechanism of moisture on the hyperspectral characteristics of the mattic epipedon. The established MSC+SD-XGBoost model adapts to varying moisture conditions, providing technical support for the rapid monitoring of mattic epipedon degradation and holding significant practical value for carbon management in alpine ecosystems. Full article

The internal growth patterns and surface micromorphology of diamonds provide a record of their multi-stage evolution, from initial formation within the mantle to their eventual ascent to the Earth’s surface via deeply derived kimberlite magmas. In this study, gemological microscopic examination, Diamond View^TM, Raman spectroscopy, and electron probe analysis were employed to analyze the surface features, internal patterns, and inclusions of the Tancheng alluvial diamonds in Shandong Province, China. The results show that surface features of octahedra with triangular and sharp edges, thick steps with irregular contours or rounded edges, and thin triangular or serrated layers are developed on diamonds during deep-mantle storage, as well as during the growth process of diamonds, when they are not subjected to intense dissolution. The rounding of octahedral and cubic diamond edges and their transformation into tetrahedral (THH) shapes are attributed to resorption in kimberlitic magma. These characteristics indicate that the Tancheng diamonds were commonly resorbed by carbonate–silicate melts during mantle storage. Abnormal birefringence phenomena, including irregular extinction patterns, petaloid and radial extinction patterns, and banded birefringence, were formed during the diamond growth stage. In contrast, fine grid extinction patterns and composite superimposed extinction patterns are related to later plastic deformation. The studied diamonds mainly contain P-type inclusions of olivine and graphite, with a minority of E-type inclusions, including coesite and omphacite. The pressure of entrapment of olivine inclusions within the Tancheng diamonds ranges from 4.3 to 5.9 GPa, which is consistent with that of coesite inclusions, which yield pressure ranging from 5.2 to 5.5 GPa, and a temperature range of 1083–1264 °C. Overall, the evidence suggests that Tancheng diamonds probably originated from hybrid mantle sources metasomatized by the subduction of ancient oceanic lithosphere. Full article

Background: Health departments disseminate health education related to influenza to the public through various media in China. We examined knowledge, attitudes, and practices regarding influenza and the influenza vaccine (KAP-flu) over time among pregnant women (PW) compared to non-PW. Methods: A cross-sectional survey was conducted in Suzhou, China in 2013 and 2023. We included and interviewed PW seeking prenatal care and excluded PW there for non-routine visits. The comparison group was drawn from non-PW seeking physical examinations at the same facilities. Stratified cluster sampling was used to enroll participants from the various levels of prenatal-care facilities. Results: In 2013, we surveyed 1673 PW and 401 non-PW, and in 2023, we surveyed 2195 PW and 1171 non-PW. The proportion of PW who had ever heard of the influenza vaccine showed no significant change, at 56% in 2013 and 57% in 2023; by contrast, there was a significant increase among non-PW (55% to 78%). The proportion of pregnant participants who knew when to get vaccinated dropped from 14% to 12%, in contrast to the increase among non-PW (6% to 20%). The proportion of PW who believed that the influenza vaccine is effective dropped from 91% in 2013 to 76% in 2023, in contrast to the stable value among non-PW (84% to 82%). In 2023, pregnant participants exhibited lower levels of knowledge about both influenza disease and the influenza vaccine, along with less positive attitudes toward the effectiveness and safety of the vaccine. They also showed lower willingness to vaccinate and lower vaccination rates compared to non-pregnant participants. Concerning KAP-flu among PW, less than half recognized that influenza is different from a common cold; fewer than one in five understood the timing and frequency of vaccination or the policy prioritizing PW for influenza vaccination; vaccination coverage remained below 2% over time. Conclusions: PW had concerning gaps in knowledge and attitudes regarding influenza and the influenza vaccine compared to non-PW in Suzhou, China. Specific actions targeting PW, such as initiatives leveraging the maternal and child healthcare system, are warranted to reduce the gaps. Full article

The hydrogen economy, associated with electrochemical water splitting, represents a promising pathway to mitigate reliance on fossil fuels. However, the efficiency of this process is constrained by the sluggish oxygen evolution reaction (OER) at the anode, with low commercial interests of the produced oxygen. As a promising solution, OER can be replaced with the methanol oxidation reaction (MOR), which not only accelerates the hydrogen evolution reaction (HER) but also yields valuable formate as a product, depending on the nature of the anode electrocatalysts. In this context, nickel selenides have emerged as highly efficient and cost-effective electrocatalysts due to their rich compositional diversity, tunable electronic structures, and superior conductivity. Additionally, nickel selenides exist in multiple stoichiometric and nonstoichiometric phases, and also in the engineering versatility for optimizing catalytic MOR performance. This review comprehensively presents the design principles of electrocatalysts, provides a strategy for the optimization of performance, and discusses the mechanistic understanding of nickel selenide-based electrocatalysts for coupled HER and MOR systems, particularly focusing on the MOR. By bridging fundamental insights with practical applications, it additionally highlights the latest advancements in their catalytic MOR performance, offering insights into their potential for future energy and chemical applications. Full article

Objective: To develop and validate a composite model that combines lesion–symptom mapping (LSM), radiomic information, and clinical factors for predicting cerebellar mutism syndrome in pediatric patients suffering from posterior fossa tumors. Methods: A retrospective analysis was conducted on a cohort of 247 (training set, n = 174; validation set, n = 73) pediatric patients diagnosed with posterior fossa tumors who underwent surgery at Beijing Children’s Hospital. Presurgical MRIs were used to extract the radiomics features and voxel distribution features. Clinical factors were derived from the medical records. Group comparison was used to identify the clinical risk factors of CMS. Combining location weight, radiomic features from tumor area and the significant intersection area, and clinical variables, hybrid models were developed and validated using multiple machine learning models. Results: The mean age of the cohort was 4.88 [2.89, 7.78] years, with 143 males and 104 females. Among them, 73 (29.6%) patients developed CMS. Gender, location, weight, and five radiomic features (three in the tumor mask area and two in the intersection area) were selected to build the model. The four models, KNN model, GBM model, RF model, and LR model, achieved high predictive performance, with AUCs of 0.84, 0.83, 0.81, and 0.87, respectively. Conclusions: CMS can be predicted using MRI features and clinical factors. The combination of radiomics and tumoral location weight could improve the prediction of CMS. Full article

The structure and magnetic properties of Sm_6−xLa_xMn₂₃ (x = 0.5, 1, 2, 3 and 4) alloys have been studied systematically. We found that the Th₆Mn₂₃-type Sm_6−xLa_xMn₂₃ alloys become less stable with increasing La content, and α-Mn becomes the dominant phase at x = 4. More impurities were found to present in Sm₅LaMn₂₃ samples prepared by a rapid solidification process than those present in the as-cast ingots. The coercivity of Sm₄La₂Mn₂₃ induction-melted ingots and Sm₅LaMn₂₃ melt-spun ribbons reached up to 0.47 T and 0.53 T, respectively, indicating potential applications of this alloy in hard magnetic materials. The Curie temperature of Sm_6−xLa_xMn₂₃ falls in the range of 398 K for x = 1 to 438 K for x = 3. The La-substitution results in a reduced saturation magnetization of Sm_6−xLa_xMn₂₃, owing to a reduced total-magnetic-moment contribution of the Sm-sublattices. This work provides us a deeper understanding of the effect of La-substitution on the structure and magnetic properties of the ternary La-Sm-Mn alloys. Full article

Environmental pollution significantly exacerbates various diseases, particularly those affecting the cardiovascular and respiratory systems. Our previous studies have shown that acrolein, an environmental pollutant, promotes atherosclerosis by downregulating the circadian clock genes (CLOCK/BMAL1) and disrupting circadian rhythm. We have also found that intermittent fasting (IF), closely linked to the circadian clock, may mitigate atherosclerosis induced by acrolein. Ferroptosis, a newly identified form of regulated cell death, is associated with the acceleration of atherosclerotic development, but its relationship with the circadian clock is not well understood. In this study, we explored the potential of IF to alleviate ferroptosis by modulating the circadian clock. Our in vivo experiments revealed that IF reversed ferroptosis and upregulated CLOCK/BMAL1 in APOE-/- mice. In human umbilical vein endothelial cells (HUVECs), we discovered that acrolein-induced ferroptosis leads to cell death, while short-term starvation (STS, IF cell model) reversed this effect. Acrolein also suppressed the expression of AMP-activated protein kinase (AMPK), nuclear factor erythroid 2-related factor 2 (NRF2), and CLOCK/BMAL1, which were restored by subsequent STS treatments. Additionally, the overexpression of CLOCK/BMAL1 mitigated ferroptosis, consistent with findings from CLOCK gene knockout experiments. Notably, CLOCK/BMAL1 and AMPK/NRF2 were found to be mutually regulated. Concurrently, the AMPK and NRF2 signaling pathways may be interdependent and act in concert. In conclusion, our findings suggest that IF modulates the CLOCK/BMAL1-AMPK/NRF2 pathway to alleviate acrolein-induced ferroptosis, offering a potential strategy to address health issues related to environmental pollution. Full article

Ge Hong, a religious thinker, has a philosophy of life that integrates Confucianism and Daoism that is reflected in his theory of human nature and destiny. It is embodied in several related concepts. First, “human nature and destiny are inherently natural”. This means that human nature and destiny are inevitable and determined. On the one hand, Ge Hong denied this concept to demonstrate the possibility of immortality; on the other hand, he accepted it in terms of whether an individual could become an immortal. This gave his thought a distinct dualist feature. Second, the “law of human nature and destiny” served as the foundation for discussing the rationality of the cultivation of immortality during the Wei and Jin Dynasties. Ge Hong also used the law to demonstrate the rationality of the way to immortality. Third, the essence of the way to immortality can be presented through the theory of human nature and destiny, which is to transform humans into immortals through certain means, known as “transforming life and destiny”. Full article