Background Transcranial direct current stimulation (tDCS) may have a potential for improving post-stroke dysphagia. Objective The purpose of this study was to examine the effect of tDCS on improving dysphagia in stroke patients. Patients and methods Forty stroke patients were divided randomly into two equal groups (the study (group A) and control groups (group B). Group A received a physical therapy program and active (tDCS), and group B received the same physical therapy program and sham (tDCS). The Dysphagia Outcome and Severity Scale (DOSS) and videofluoroscopy were performed in all patients before and after 2 weeks of the treatment program. Results Before treatment, there were no significant differences between the two groups for DOSS score or digital fluoroscopic findings. After treatment, there were significant differences between the study and control group for DOSS score and digital fluoroscopic findings. Conclusion Anodal tDCS is effective in improving dysphagia in stroke patients.
Surfactants are superior to polymers in reducing drag and their advantages are very well established. As drag reducers, several factors, such as concentration, temperature, salinity, shear rate, etc., can affect their behavior. Other unique factors relevant to surfactants may include tubing diameter (scale-up effect), head group structure, counterion, charge, etc. Although, drag reduction envelope is customarily employed to investigate drag reduction phenomena, it is defined only for polymeric fluids in both straight and coiled tubing and for surfactant-based (SB) fluids in straight tubing. No such envelope is available for SB fluids in coiled tubing. The present research aims at experimentally investigating the drag reduction characteristics of the most widely used Aromox APA-T surfactant-based fluids. It is a highly active surfactant used as gelling agent in aqueous and brine base fluids. Flow data are gathered using small and large scale flow loops. Straight and coiled tubing with various sizes (1.27 cm to 7.30 cm o.d.) and curvature ratios (0.01 to 0.031) covering the field application range are utilized. The results show that SB fluids exhibit superior drag reduction characteristics. Their behavior is significantly affected by surfactant concentration, shear, tubing size, and geometry. Higher drag reduction is seen in straight tubing than in coiled tubing and increasing curvature ratio yields higher friction pressure losses. In coiled tubing, SB fluids exhibit better drag reduction characteristics than Shah and Zhou maximum drag reduction (MDR) asymptote for polymeric fluids. Therefore, a new maximum drag reduction asymptote is developed using data gathered in 1.27 cm o.d. tubing. The proposed correlation agrees with Zakin MDR asymptote for SB fluids in straight tubing where the curvature ratio is set to be zero. Employing the proposed correlation, a modified drag reduction envelope can be used to evaluate drag reduction characteristics of SB fluids.
Low-damage fracturing fluids are normally used for better fracture-dimension confinement and lower residue. This leads not only to longer fracture lengths, but also to higher fracture conductivity. Slickwater fracturing technology, developed in the 1980s, is less expensive than gel treatments. Fluid and proppant volumes can be reduced, and treatment flow rates can be increased significantly. When compared to conventional gel treatments, slickwater fracturing can generate similar or better production responses.In frac treatments, slickwater is pumped through straight tubing (ST) and coiled tubing (CT). As a result of secondary flow, frictional pressure losses in CT are higher than in ST. Determining these losses is of the utmost importance for successful treatments. Customarily, laboratory-generated flow data are used to develop correlations to predict frictional pressure loss of fluids flowing in ST and CT. These correlations are then, without verification, applied to field applications, which employ much larger conduit sizes.The present study is aimed to experimentally investigate the hydraulic properties of a commonly used drag reducer-Nalco ASP-820-in larger tubing sizes. This is a modified partially hydrolyzed polyacrylamide (PHPA). Previously, we reported flow data gathered employing ½-in. ST and CT (varying curvature ratio) and the correlations developed to predict frictional pressure losses of fluids in ST and CT. In this investigation, the large-scale flow data acquired from 200-ft ST and 1,000-, 2,000-, and 3,000-ft, 1½-in. CT, and 1,000-ft 2 3 ⁄8-and 2 7 ⁄8-in. CT, are compared with the predictions from the correlations developed from ½-in.-pipe data. The effects of shear intensity, shear duration, and pipe roughness on flow properties of the ASP-820 fluid are also investigated.Results show significantly lower drag reduction in CT than in ST because of secondary flow caused by the CT curvature. Polymer degradation because of shear (shear intensity and duration) and/or tubing roughness can reduce drag reduction significantly. The results are discussed in light of a recently developed "dragreduction envelope" to evaluate the drag reduction characteristics of slickwater fluid in ST and CT.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.