Numerical Analysis of the Factors Influencing the Erosion of the Valve Port of a High-Speed On/Off Valve

Aiming at the problem of valve port erosion caused by contaminated particles, a three-dimensional prediction model of valve orifice erosion was established based on computational fluid dynamics (CFD) and erosion theory, considering the influence of the valve port eddy current on the oil flow. The discrete phase model (DPM) of fluent is used to obtain the orifice erosion location and erosion rate, and the causes of erosion of the high-speed on/off valve are analyzed. On this basis, several factors influencing valve port erosion are simulated to investigate the relationship between particle collision behavior and valve port erosion morphology under different factors, and the change rule of valve port erosion under different factors is analyzed. The results show that the high-speed on/off valve service life decreases with a larger cone angle of the spool, a larger pressure difference at the valve port, a larger proportion of large particle contaminants in the oil, a higher oil contamination level, and a larger filter aperture. In addition, the grey relational analysis method is used to clarify the pressure difference at the valve port, the particle size, and the filter aperture as the three most important factors affecting the erosion of the valve port of a high-speed on/off valve

Numerical Analysis of the Factors Influencing the Erosion of the Valve Port of a High-Speed On/Off Valve

Aiming at the problem of valve port erosion caused by contaminated particles, a three-dimensional prediction model of valve orifice erosion was established based on computational fluid dynamics (CFD) and erosion theory, considering the influence of the valve port eddy current on the oil flow. The discrete phase model (DPM) of fluent is used to obtain the orifice erosion location and erosion rate, and the causes of erosion of the high-speed on/off valve are analyzed. On this basis, several factors influencing valve port erosion are simulated to investigate the relationship between particle collision behavior and valve port erosion morphology under different factors, and the change rule of valve port erosion under different factors is analyzed. The results show that the high-speed on/off valve service life decreases with a larger cone angle of the spool, a larger pressure difference at the valve port, a larger proportion of large particle contaminants in the oil, a higher oil contamination level, and a larger filter aperture. In addition, the grey relational analysis method is used to clarify the pressure difference at the valve port, the particle size, and the filter aperture as the three most important factors affecting the erosion of the valve port of a high-speed on/off valve

The Effectiveness and Safety of Manual Acupuncture Therapy in Patients with Poststroke Cognitive Impairment: A Meta-analysis

Background. Poststroke cognitive impairment (PSCI) is a common cause of disability among patients with stroke. Meanwhile, acupuncture has increasingly been used to improve motor and cognitive function for stroke patients. The aim of the present study was to summarize and evaluate the evidence on the effectiveness of acupuncture in treating PSCI. Methods. Eight databases (PubMed, The Cochrane Library, CNKI, WanFang Data, VIP, CBM, Medline, Embase databases) were searched from January 2010 to January 2020. Meta-analyses were conducted for the eligible randomized controlled trials (RCTs). Assessments were performed using Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Barthel Index (BI), or modified Barthel Index (MBI). Results. A total of 657 relevant RCTs were identified, and 22 RCTs with 1856 patients were eventually included. Meta-analysis showed that acupuncture appeared to be effective for improving cognitive function as assessed by MMSE (mean difference MD=1.73, 95% confidence interval (CI) (1.39, 2.06), P<0.00001) and MoCA (MD=2.32, 95% CI (1.92, 2.73), P<0.00001). Furthermore, it also suggested that acupuncture could improve the activities of daily life (ADL) for PSCI patients as assessed by BI or MBI (SMD=0.97, 95% CI (0.57, 1.38), P<0.00001). Conclusions. Compared with nonacupuncture group, acupuncture group showed better effects in improving the scores of MMSE, MoCA, BI, and MBI. This meta-analysis provided positive evidence that acupuncture may be effective in improving cognitive function and activities of daily life for PSCI patients. Meanwhile, long retention time of acupuncture may improve cognitive function and activities of daily life, and twist technique may be an important factor that could influence cognitive function. However, further studies using large samples and a rigorous study design are needed to confirm the role of acupuncture in the treatment of PSCI

The mechanistic effects of acupuncture in rodent neurodegenerative disease models: a literature review

Neurodegenerative diseases refer to a battery of medical conditions that affect the survival and function of neurons in the brain, which are mainly presented with progressive loss of cognitive and/or motor function. Acupuncture showed benign effects in improving neurological deficits, especially on movement and cognitive function impairment. Here, we reviewed the therapeutic mechanisms of acupuncture at the neural circuit level in movement and cognition disorders, summarizing the influence of acupuncture in the dopaminergic system, glutamatergic system, γ-amino butyric acid-ergic (GABAergic) system, serotonergic system, cholinergic system, and glial cells at the circuit and synaptic levels. These findings can provide targets for clinical treatment and perspectives for further studies

Abacus Training Modulates the Neural Correlates of Exact and Approximate Calculations in Chinese Children: An fMRI Study

Exact (EX) and approximate (AP) calculations rely on distinct neural circuits. However, the training effect on the neural correlates of EX and AP calculations is largely unknown, especially for the AP calculation. Abacus-based mental calculation (AMC) is a particular arithmetic skill that can be acquired by long-term abacus training. The present study investigated whether and how the abacus training modulates the neural correlates of EX and AP calculations by functional magnetic resonance imaging (fMRI). Neural activations were measured in 20 abacus-trained and 19 nontrained Chinese children during AP and EX calculation tasks. Our results demonstrated that: (1) in nontrained children, similar neural regions were activated in both tasks, while the size of activated regions was larger in AP than those in the EX; (2) in abacus-trained children, no significant difference was found between these two tasks; (3) more visuospatial areas were activated in abacus-trained children under the EX task compared to the nontrained. These results suggested that more visuospatial strategies were used by the nontrained children in the AP task compared to the EX; abacus-trained children adopted a similar strategy in both tasks; after long-term abacus training, children were more inclined to apply a visuospatial strategy during processing EX calculations

Effects of Highway-Related Pollutant on the Groundwater Quality of Turfy Swamps in the Changbai Mountain Area

Transportation activities such as fuel consumption, vehicle wear and road deicing can detrimentally affect the groundwater quality of fragile roadside wetland environments including. Nineteen parameters (Cu, Pb, Zn, Cd, Cr, Ni, Hg, As, pH, TDS, Ca2+, Mg2+, Na+, K+, SO42&minus;, Cl&minus;, HCO3&minus;, NO3&minus; and F&minus;) were determined in groundwater samples from turfy swamps impacted by highway traffic from Jiangyuan (JY), Longquan (LQ), and Huangsongdian (HSD). Our results indicate that the metals Cu, Pb, Zn, Cr, Cd, the ions Na+, K+ and Cl&minus; in groundwater were negatively affected by highway transportation, and the maximum affected distance of these pollutants varied from 15 to 100 m. The content of most of these pollutants in roadside groundwater decreased exponentially with the distance from the highway, as did the heavy metal pollution index HPI and Cd. The values of HPI and Cd in these three sites ranged from 46.8 to 78.4 and &minus;4.9 to &minus;2.9, respectively. The low pollution levels of heavy metals are related to the strong adsorption capacity of turfy soil towards metals. In any case, road transport activities increased the Cu, Pb, Zn, Cr, Cd, Na+, K+ and Cl&minus; content in roadside groundwater in turfy swamp. With the increase of highway operation time, it will inevitably have a great influence on the groundwater quality of these wetlands. Therefore, the long-term monitoring is necessary to protect the sustainable development of turfy swamp

A durable and pH-universal self-standing MoC-Mo2C heterojunction electrode for efficient hydrogen evolution reaction.

Efficient water electrolyzers are constrained by the lack of low-cost and earth-abundant hydrogen evolution reaction (HER) catalysts that can operate at industry-level conditions and be prepared with a facile process. Here we report a self-standing MoC-Mo2C catalytic electrode prepared via a one-step electro-carbiding approach using CO2 as the feedstock. The outstanding HER performances of the MoC-Mo2C electrode with low overpotentials at 500 mA cm-2 in both acidic (256 mV) and alkaline electrolytes (292 mV), long-lasting lifetime of over 2400 h (100 d), and high-temperature performance (70 oC) are due to the self-standing hydrophilic porous surface, intrinsic mechanical strength and self-grown MoC (001)-Mo2C (101) heterojunctions that have a ΔGH* value of -0.13 eV in acidic condition, and the energy barrier of 1.15 eV for water dissociation in alkaline solution. The preparation of a large electrode (3 cm × 11.5 cm) demonstrates the possibility of scaling up this process to prepare various carbide electrodes with rationally designed structures, tunable compositions, and favorable properties

Study of Temperature Field Distribution in Topographic Bias Tunnel Based on Monitoring Data

In recent decades, numerous tunnels have been built in the cold region of China. However, the temperature field of topographically biased tunnels in the monsoon freeze zone has not been sufficiently studied. In this study, we monitored the temperature of the surrounding rock in two topographic bias sections of the Huitougou Tunnel and analyzed the results by fitting them to the monitoring results. The results showed that the temperature of the surrounding rock on both sides after tunnel excavation varied periodically in an approximate triangular function. As the distance from the cave wall increased, the annual average temperature of the surrounding rock did not change significantly, the amplitude decreased, and the delay time increased, while the annual maximum temperature decreased, and the annual minimum temperature increased. The heat generated by blasting, the heat of hydration of the primary and secondary lining, and the decorated concrete all caused a significant increase in the temperature of the surrounding rock within 4 m for a short period of time. Both construction and topographic factors led to asymmetry in the distribution of the surrounding rock temperature in different ways. The results of this paper are intended as a reference for other studies on temperature in deviated tunnels

Organelle-Specific Nitric Oxide Detection in Living Cells via HaloTag Protein Labeling

<div><p>Nitric oxide (NO) is a membrane-permeable signaling molecule that is constantly produced, transferred, and consumed <i>in vivo</i>. NO participates and plays important roles in multiple biological processes. However, spatiotemporal imaging of NO in living cells is challenging. To fill the gap in currently used techniques, we exploited the versatility of HaloTag technology and synthesized a novel organelle-targetable fluorescent probe called HTDAF-2DA. We demonstrate the utility of the probe by monitoring subcellular NO dynamics. The developed strategy enables precise determination of local NO function.</p></div