Effect of N on the Microstructure and Wear Resistance of 4Cr13 Corrosion-Resistant Plastic Mold Steel.

The effect of N content on the microstructure and wear resistance of 4Cr13 corrosion-resistant plastic mold steel were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tribometer. The results showed that the influence mechanism of nitrogen on the hardness of the test steels responded to the changes in the quenching temperature. When the quenching temperature was below 1050 °C, the solid solution strengthening of N played a dominant role as a wear mechanism, and as the N content increased, the hardness of the steel increased. When the quenching temperature was higher than 1050 °C, N increased the residual austenite content, resulting in a decrease in hardness. The addition of N reduced the optimal quenching temperature of the test steels. The N addition promoted the transformation of large-sized M23C6 to M23C6 and fine Cr2N, resulting in an increase in the hardness of the test steels. The influence on the wear resistance of the experimental steels differed according to the varied N contents. The addition of 0.1% N delayed the precipitation of large- sized particles in the second phase, increased the hardness of the steel, and reduced the degree of wear. However, an excessive addition of N (0.18%) led to the excessive precipitation of the second-phase particles, and the second-phase particles then gradually flaked during the wear process and continued to participate in the wear process as third-body abrasives, reducing wear resistance.

A systematic review and meta-analysis of the effects of early mobilization therapy in patients after cardiac surgery.

BACKGROUND: Prolonged hospitalization and immobility of critical care patients elevate the risk of long-term physical and cognitive impairments. However, the therapeutic effects of early mobilization have been difficult to interpret due to variations in study populations, interventions, and outcome measures. We conducted a meta-analysis to assess the effects of early mobilization therapy on cardiac surgery patients in the intensive care unit (ICU). METHODS: PubMed, Excerpta Medica database (EMBASE), Cumulative Index of Nursing and Allied Health Literature (CINAHL), Physiotherapy Evidence Database (PEDro), and the Cochrane Library were comprehensively searched from their inception to September 2018. Randomized controlled trials were included if patients were adults (≥18 years) admitted to any ICU for cardiac surgery due to cardiovascular disease and who were treated with experimental physiotherapy initiated in the ICU (pre, post, or peri-operative). Data were extracted by 2 reviewers independently using a pre-constructed data extraction form. Length of ICU and hospital stay was evaluated as the primary outcomes. Physical function and adverse events were assessed as the secondary outcomes. Review Manager 5.3 (RevMan 5.3) was used for statistical analysis. For all dichotomous variables, relative risks or odds ratios with 95% confidence intervals (CI) were presented. For all continuous variables, mean differences (MDs) or standard MDs with 95% CIs were calculated. RESULTS: The 5 studies with a total of 652 patients were included in the data synthesis final meta-analysis. While a slight favorable effect was detected in 3 out of the 5 studies, the overall effects were not significant, even after adjusting for heterogeneity. CONCLUSIONS: This population-specific evaluation of the efficacy of early mobilization to reduce hospitalization duration suggests that intervention may not universally justify the labor barriers and resource costs in patients undergoing non-emergency cardiac surgery. PROSPERO RESEARCH REGISTRATION IDENTIFYING NUMBER: CRD42019135338.

Electroacupuncture Regulates Hippocampal Synaptic Plasticity via Inhibiting Janus-Activated Kinase 2/Signal Transducer and Activator of Transcription 3 Signaling in Cerebral Ischemic Rats.

OBJECTIVE: To determine the mechanism(s) involved in electroacupuncture (EA)-mediated improvements in synaptic plasticity in a rat model of middle cerebral artery occlusion and reperfusion (MCAO/R)-induced cognitive deficits. METHODS: Focal cerebral ischemic stroke was induced by (MCAO/R) surgery. Rats were randomly split into 4 groups: control group (sham operation control), MCAO group, Baihui (GV 20) and Shenting (GV 24) acupoint EA group (verum acupuncture, MCAO + VA), and nonacupoint EA group (control acupuncture, MCAO + CA). EA treatment was administered for 14 consecutive days in MCAO + VA and MCAO + CA groups. Neurological assessment, behavioral performance testing, and molecular biology assays were used to evaluate the MCAO/R model, EA therapeutic effect and potential therapeutic mechanism(s) of EA. RESULTS: Significant amelioration of neurological deficits was found in MCAO + VA rats compared with MCAO rats (P < .01). Moreover, learning and memory significantly improved in EA-treated rats compared with MCAO or MCAO + CA rats (P < .05) together with an increase in the number of PSD-95+ and SYN+ cells and synapses in the hippocampal CA1 region (P < .05). MCAO + VA rats also showed amelioration of pathological synaptic ultrastructural changes compared with MCAO or MCAO + CA groups (P < .001). In contrast, EA decreased the levels and phosphorylation of JAK2 (Janus-activated kinase 2) and STAT3 (signal transducer and activator of transcription 3) in the hippocampal CA1 region compared with MCAO or MCAO + CA group (P < .01). CONCLUSION: EA at GV 20 and GV 24 acupoints improved cognitive deficits in cerebral ischemic rats via the JAK2/STAT3 signaling pathway and mediated synaptic plasticity in the peri-infarct hippocampal CA1 region of rats following ischemic stroke.

Electroacupuncture exerts anti-inflammatory effects in cerebral ischemia-reperfusion injured rats via suppression of the TLR4/NF-κB pathway.

Inflammatory response has been shown to play a critical role in brain damage after cerebral ischemia-reperfusion (I/R) injury, which is tightly regulated by the Toll-like receptor (TLR)4/nuclear factor (NF)-κB pathway; therefore, suppression of TLR4/NF-κB signaling has become a promising target for the anti-inflammatory treatment in ischemic stroke. Acupuncture has been used as a complementary and alternative therapy practice that supplements conventional medicine. Numerous studies have demonstrated the clinical efficacy of acupuncture in stroke rehabilitation. However, the precise mechanism of its neuroprotective effect remains poorly understood. Using a focal cerebral I/R injured rat model, in the present study we evaluated the neuroprotective and anti-inflammatory activities of electroacupuncture at Quchi and Zusanli, and investigated the underlying molecular mechanisms. We found that electroacupuncture at Quchi (LI11) and Zusanli (ST36) acupoints significantly improved the ischemia-associated scores of neurological deficits, reduced cerebral infarction and alleviated inflammatory responses. Moreover, the crucial signaling molecules in the TLR4/NF-κB signaling pathway were regulated by acupuncture, which coincided with suppressed secretion levels of inflammatory cytokines such as TNF-α, IL-1ß and IL-6. Our data suggest that electroacupuncture exerts a neuroprotective function in ischemic stroke through inhibition of TLR4/NF-κB-mediated inflammation.

Electroacupuncture at the Quchi and Zusanli acupoints exerts neuroprotective role in cerebral ischemia-reperfusion injured rats via activation of the PI3K/Akt pathway.

The PI3K/Akt pathway, a critical mediator of cell survival, is suppressed in cerebral ischemia/reperfusion (I/R) injury; therefore, it is a major focus in treatment of ischemic stroke. Acupuncture has long been used in China to clinically treat stroke. However, the precise mechanism of its neuroprotective activities remains largely unknown. Using a focal cerebral I/R injured rat model, in the present study we evaluated the in vivo therapeutic efficacy of electroacupuncture and investigated the underlying molecular mechanisms. We found that electroacupuncture at Quchi (LI11) and Zusanli (ST36) acupoints on the contralateral paralyzed limb significantly improved neurological deficits and cerebral infarction. In addition, electroacupuncture profoundly activated PI3K/Akt signaling in ischemic cerebral tissues. Consequently, the upregulatory effect of electroacupuncture on PI3K/Akt activation resulted in the inhibition of cerebral cell apoptosis. Moreover, electroacupuncture increased the serum secretion levels of the PI3K activators BDNF and GDNF, as well as upregulated the anti-apoptotic Bcl-2/Bax ratio in ischemic cerebrum. Our data suggest that electroacupuncture at Quchi and Zusanli acupoints exerts neuroprotective function in ischemic stroke via activation of the PI3K/Akt pathway.