Comparative study of acid functionization of carbon nanotube via ultrasonic and reflux mechanism

© 2018 Elsevier Ltd. Multi-walled carbon nanotubes (MWCNTs) have a great potential in wide applications due to their extraordinary physical, thermal and mechanical properties. However, the known shortcomings, such as hydrophobic nature, poor solubility and dispersibility in most solvents have impeded the technology to further develop. In the present study, various types of acid functionalized MWNCTs (f-MWCNTs) samples were prepared. The investigated process parameters include type of acids, acid concentrations, treatment methods, operating temperature and treatment duration. The f-MWCNTs were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive X-ray (EDX), Field Emission Scanning Electron Microscopy (FESEM) and Zetasizer. The optimum conditions for acid functionalization of MWCNTs were achieved by dispersing MWCNTs in concentrated nitric and sulfuric acid mixture (1:3 v/v ratio), via ultrasonication treatment method at 40 °C for 2.5 h. EDX analysis also revealed that, 21.36 wt% of oxygenated functional groups, with no strong detection of inorganic and metal impurities. In addition, FESEM results also revealed that there is no any severe structural damage on the surface. Acid functionalization of MWCNTs via ultrasonic bath methods is more desirable than reflux method as it can result in high yields of MWCNTs with high density of oxygenated functional groups and minimum structural destruction on the surface of MWCNTs

Common surgical procedures in pilonidal sinus disease: A meta-analysis, merged data analysis, and comprehensive study on recurrence

Abstract We systematically searched available databases. We reviewed 6,143 studies published from 1833 to 2017. Reports in English, French, German, Italian, and Spanish were considered, as were publications in other languages if definitive treatment and recurrence at specific follow-up times were described in an English abstract. We assessed data in the manner of a meta-analysis of RCTs; further we assessed non-RCTs in the manner of a merged data analysis. In the RCT analysis including 11,730 patients, Limberg & Dufourmentel operations were associated with low recurrence of 0.6% (95%CI 0.3–0.9%) 12 months and 1.8% (95%CI 1.1–2.4%) respectively 24 months postoperatively. Analysing 89,583 patients from RCTs and non-RCTs, the Karydakis & Bascom approaches were associated with recurrence of only 0.2% (95%CI 0.1–0.3%) 12 months and 0.6% (95%CI 0.5–0.8%) 24 months postoperatively. Primary midline closure exhibited long-term recurrence up to 67.9% (95%CI 53.3–82.4%) 240 months post-surgery. For most procedures, only a few RCTs without long term follow up data exist, but substitute data from numerous non-RCTs are available. Recurrence in PSD is highly dependent on surgical procedure and by follow-up time; both must be considered when drawing conclusions regarding the efficacy of a procedure