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.     

Factors leading to long-term hospitalization after laparoscopic appendectomy.

BACKGROUND: Randomized studies demonstrate that laparoscopic appendectomy yields better results compared with open techniques. We sought to identify factors that determine an extended hospital stay among patients undergoing laparoscopic appendectomy. METHODS: This was a prospective study including 669 patients undergoing laparoscopic appendectomy. We analyzed variables that can predict the length of hospital stay. RESULTS: Of 669 patients undergoing laparoscopic appendectomy, 141 stayed in the hospital for > or = 5 days (Group 1), and 97 stayed in the hospital for < or = 1 day after surgery (Group 2). The univariate analysis demonstrated that fever (P<0.0001), nausea and vomiting (P=0.060), leukocytosis (P<0.0001), gangrened or perforated intraoperative appearance of the appendix (P<0.0001), and appendix position behind the ileocecal junction (P<0.001) were related to a longer hospital stay. The multivariate analysis through logistical regression showed that the factors independently and significantly associated with an extended hospital stay were presurgical fever, appendix position behind the ileocecal junction, and intraoperative gangrened or perforated appearance of the appendix. CONCLUSION: Fever, appearance, and position of the appendix are factors related to an extended hospital stay.     

A systematic review of the oral and craniofacial manifestations of cri du chat syndrome

Cri du chat syndrome is an autosomal disorder. Because it affects few people in the population it is considered a rare disease, yet it is one of the most common autosomal chromosomal syndromes in humans. It entails pathognomonic alterations that affect the craniofacial and oral anatomy of patients. The aim of this study is to review these craniofacial and oral abnormalities in patients with Cri du chat syndrome. The PubMed Medline database was searched using two different strategies. First, we used “Dentistry” and “Cri du chat” as keywords; second, we used “Cri du chat” and “craniofacial.” Seven articles in which the main orofacial and cranio‐skeletal characteristics of patients with Cri du chat syndrome were described were selected according to the inclusion and exclusion criteria. Cri du Chat syndrome entails pathognomonic characteristics in the craniofacial area (epicanthus, short philtrum, and wide nasal bridge), the oral area (mandibular retrognathism and anterior open bite) and the cranial region (alterations at the cranial base angle and a small upper airway). However, more studies on larger samples are needed to specify the orofacial and craniofacial characteristics of patients with Cri du chat syndrome more accurately. Clin. Anat. 29:555–560, 2016. © 2015 Wiley Periodicals, Inc.     

The role of cannabinoids in adult neurogenesis

The processes underpinning post-developmental neurogenesis in the mammalian brain continue to be defined. Such processes involve the proliferation of neural stem cells and neural progenitor cells (NPCs), neuronal migration, differentiation and integration into a network of functional synapses within the brain. Both intrinsic (cell signalling cascades) and extrinsic (neurotrophins, neurotransmitters, cytokines, hormones) signalling molecules are intimately associated with adult neurogenesis and largely dictate the proliferative activity and differentiation capacity of neural cells. Cannabinoids are a unique class of chemical compounds incorporating plant-derived cannabinoids (the active components of Cannabis sativa), the endogenous cannabinoids and synthetic cannabinoid ligands, and these compounds are becoming increasingly recognized for their roles in neural developmental processes. Indeed, cannabinoids have clear modulatory roles in adult neurogenesis, probably through activation of both CB₁ and CB₂ receptors. In recent years, a large body of literature has deciphered the signalling networks involved in cannabinoid-mediated regulation of neurogenesis. This timely review summarizes the evidence that the cannabinoid system is intricately associated with neuronal differentiation and maturation of NPCs and highlights intrinsic/extrinsic signalling mechanisms that are cannabinoid targets. Overall, these findings identify the central role of the cannabinoid system in adult neurogenesis in the hippocampus and the lateral ventricles and hence provide insight into the processes underlying post-developmental neurogenesis in the mammalian brain.     

Patient positioning variations to reduce dose to normal tissues during 3D conformal radiotherapy for high-risk prostate cancer

BACKGROUND AND PURPOSE: The goal of this work was to assess optimal treatment positioning of 3D conformal radiotherapy (3DCRT) for high-risk prostate cancer patients. PATIENTS AND METHODS: Treatment plans of 25 patients in different patient positions were evaluated: with knee and ankle support (KAS) in the supine position and with a belly board (BB) in the prone position both with full (FB) and empty bladder (EB). Planning target volumes (PTVs) for pelvis, prostate and vesicles, prostate, and organs at risk (OARs) were delineated. Dose and overlapping volumes were evaluated. RESULTS: Overlapping volumes were significantly smaller with a FB than with an EB. No significant differences were found in overlapping volumes with respect to patient fixation systems, but the percentage values of dose to the OARs showed significantly better results employing KAS than a BB. A FB reduced the dose volumes to the OARs. Comparison with respect to circumference of abdomen (CA) showed significantly smaller overlapping at large CA in most of the cases. CONCLUSION: Supine position is suggested with KAS combined with a FB (especially in cases of larger CA) when using 3DCRT with planning technique modification for high-risk prostate cancer patients to reduce the dose of OARs, based on our results.