Enhancing Graphene Retention and Electrical Conductivity of Plasma-Sprayed Alumina/Graphene Nanoplatelets Coating by Powder Heat Treatment

Burning loss of graphene in the high-temperature plasma-spraying process is a critical issue, significantly limiting the remarkable performance improvement in graphene reinforced ceramic coatings. Here, we reported an effective approach to enhance the graphene retention, and thus improve the performance of plasma-sprayed alumina/graphene nanoplatelets (Al2O3/GNPs) coatings by heat treatment of agglomerated Al2O3/GNPs powders. The effect of powder heat treatment on the microstructure, GNPs retention, and electrical conductivity of Al2O3/GNPs coatings were systematically investigated. The results indicated that, with the increase in the powder heat treatment temperature, the plasma-sprayed Al2O3/GNPs coatings exhibited decreased porosity and improved adhesive strength. Thermogravimetric analysis and Raman spectra results indicated that increased GNPs retention from 12.9% to 28.4%, and further to 37.4%, as well as decreased structural defects, were obtained for the AG, AG850, and AG1280 coatings, respectively, which were fabricated by using AG powders without heat treatment, powders heat-treated at 850 °C, and powders heat-treated at 1280 °C. Moreover, the electrical conductivities of AG, AG850, and AG1280 coatings exhibited 3 orders, 4 orders, and 7 orders of magnitude higher than that of Al2O3 coating, respectively. Powder heat treatment is considered to increase the melting degree of agglomerated alumina particles, eventually leaving less thermal energy for GNPs to burn; thus, a high retention amount and structural integrity of GNPs and significantly enhanced electrical conductivity were achieved for the plasma-sprayed Al2O3/GNPs coatings

Efficacy of Acupuncture Combined with Patient-Controlled Analgesia in the Treatment of Acute Pain after Back Surgery: A Meta-Analysis

Objectives. Acupuncture is used worldwide to relieve both acute and chronic pain. Patient-controlled analgesia (PCA) is also frequently used for postoperative pain relief. However, there are few meta-analyses of the efficacy of acupuncture with PCA in reducing acute postoperative pain. This meta-analysis aimed to assess the effectiveness of acupuncture with PCA in relieving acute pain after back surgery. Methods. We searched seven databases (Cochrane Library, Web of Science, PubMed, China National Knowledge Infrastructure (CNKI), Wanfang database, Chongqing VIP (VIP), and Chinese BioMedical Literature Database (CBM)-from 1949 until now) without language restrictions for randomized controlled trials, including patients undergoing back surgery and receiving PCA alone or treated with acupuncture/sham acupuncture + PCA for pain relief. This meta-analysis assessed pain intensity, with visual analogue scale (VAS) score and postoperative opioid dosage as primary outcomes. Results. A total of 12 randomized controlled trials (n = 904) met the inclusion criteria. Compared with the control group (standard mean difference (SMD) = ‒0.42, 95% CI = ‒0.60 to ‒0.25, P<0.01) or sham acupuncture + PCA (SMD = ‒0.7, 95% CI = ‒0.94 to ‒0.46, P<0.01), acupuncture + PCA treatment reduced the VAS score in patients after back surgery. Acupuncture + PCA decreased the use of opioids after surgery compared to sham acupuncture + PCA (SMD = −0.35, 95% CI = ‒0.63 to ‒0.07, P=0.01) or control group (SMD = ‒0.82, 95% CI = ‒1.03 to ‒0.61, P<0.01). Furthermore, the use of acupuncture with PCA reduced the incidence of postoperative PCA-related total complications (odds ratio = 0.44, 95% CI = 0.23 to 0.85, P=0.01), but may not reduce the incidence of postoperative nausea and vomiting (odds ratio =0.82 , 95% CI =0.49 to 1.36, P=0.44). Conclusion. This systematic review found that acupuncture with PCA relieved acute pain after back surgery more effectively than PCA alone and could reduce opioid use and the incidence of postoperative PCA-related total complication

Core-shell nano-structured carbon composites based on tannic acid for lithium-ion batteries

Core-shell nano-structured carbon composites have been used as electrode materials in lithium-ion batteries (LIBs) with increasing attention. The large volume swing during lithiation/delithiation processes and poor electronic conductivity are two key issues in the newly-proposed electrode materials, which severely limit their practical applications in LIBs. In order to solve these problems, we report a facile and versatile method to prepare core-shell nano-structured carbon composites using low cost and widely available tannic acid as the carbon source. The carbon layers with controlled thicknesses of 6-12 nm and 1-3 nm were coated on the surface of Si and TiO2 nanoparticles, respectively. Due to the carbon layers, both the Si@C and TiO2@C nanocomposites used as anode materials in LIBs showed excellent electrochemical performances including good cycling stability and high rate capability. We believe that this method may be applicable to various carbon-coating nanocomposites.</p

Core-shell nano-structured carbon composites based on tannic acid for lithium-ion batteries

status: publishe