Ultrasound-Assist Extrusion Methods for the Fabrication of Polymer Nanocomposites Based on Polypropylene/Multi-Wall Carbon Nanotubes

Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 10¹³ to 10⁵ Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods.     

Efficacy of Oral Anticoagulation in Stroke Prevention among Sinus-Rhythm Patients Who Lack Left Atrial Mechanical Contraction after Cryoablation

The customary recommendation is that oral anticoagulation be withdrawn a few months after cryoablation for atrial fibrillation, independently of left atrial mechanical contraction in patients in sinus rhythm. Recently, a 5-fold increase in stroke has been described in sinus-rhythm patients who lack atrial mechanical contraction. One aim of this study was to evaluate the efficacy of oral anticoagulation in preventing postoperative stroke in such patients.This prospective study divided 154 sinus-rhythm patients into 2 groups, depending on the presence (108 patients) or absence (46 patients) of left atrial mechanical contraction at 6 months after surgery, and monitored them annually for 5 years. Those without left atrial contraction were maintained on acenocumarol. The primary endpoint was the occurrence of ischemic stroke.The median follow-up period was 29 ± 16 months; 4 patients (2.5%), all belonging to the group with preserved atrial contraction, had ischemic stroke; the group of patients without left atrial contraction had no episodes of stroke during follow-up. Logistic binary regression analyses showed no evidence of factors independently predictive of stroke.Among anticoagulated patients in sinus rhythm without left atrial contraction, we found the incidence of stroke to be zero. In a small, nonrandomized group such as this, we cannot discount the element of chance, yet we suggest that maintaining anticoagulation might lower the incidence of stroke in this population.     

Efectividad de un nuevo modelo de derivación telefónica compartida entre atención primaria y atención hospitalaria

Aim

The purpose of this study is to find out whether telephone referral from Primary Health Care to Internal Medicine Consult manages to reduce waiting days as compared to traditional referral. This study also aims to know how acceptable is the telephone referral to general practitioners and their patients.

Is bone-cement augmentation of screw-anchor fixation systems superior in unstable femoral neck fractures? A biomechanical cadaveric study

Objectives

Improved fixation techniques with optional use of bone cements for implant augmentation have been developed to enhance stability and reduce complication rates after osteosynthesis of femoral neck fractures. This biomechanical study aimed to evaluate the effect of cement augmentation on implant anchorage and overall performance of screw-anchor fixation systems in unstable femoral neck fractures.