Impact of MOV models on asymmetrical fault current calculations in fixed series compensated lines

The investigation carried out in the paper addresses the effect of series compensation on short circuit calculations in Extra High Voltage (EHV) system. Whenever the fault occurs, the Metal Oxide Varistor (MOV) bypasses the series capacitor in that particular phase causing unbalance in the network The sequence matrix representing the network becomes coupled and makes the calculation of fault current difficult as compared to normal fault analysis method. The work presented in this paper, proposed a new method for calculating short circuit current for different asymmetrical faults in the network Different models of MOV are considered in the study. Based on the investigations, appropriateness of the proposed method has been justified

Early osseointegration of a strontium containing glass ceramic in a rabbit model

The most important property of a bone cement or a bone substitute in load bearing orthopaedic implants is good integration with host bone with reduced bone resorption and increased bone regeneration at the implant interface. Long term implantation of metal-based joint replacements often results in corrosion and particle release, initiating chronic inflammation leading onto osteoporosis of host bone. An alternative solution is the coating of metal implants with hydroxyapatite (HA) or bioglass or the use of bulk bioglass or HA-based composites. In the above perspective, the present study reports the in vivo biocompatibility and bone healing of the strontium (Sr)-stabilized bulk glass ceramics with the nominal composition of 4.5SiO(2)-3Al(2)O(3)-1.5P(2)O(5)-3SrO-2SrF(2) during short term implantation of up to 12 weeks in rabbit animal model. The progression of healing and bone regeneration was qualitatively and quantitatively assessed using fluorescence microscopy, histological analysis and micro-computed tomography. The overall assessment of the present study establishes that the investigated glass ceramic is biocompatible in vivo with regards to local effects after short term implantation in rabbit animal model. Excellent healing was observed, which is comparable to that seen in response to a commercially available implant of HA-based bioglass alone. (C) 2013 Elsevier Ltd. All rights reserved

Transfection of endothelial nitric oxide synthase gene improves angiogenic efficacy of endothelial progenitor cells in rabbits with hindlimb ischemia

Background: The present study explored the effect of endothelial nitric oxide synthase (eNOS) gene transfer on the angiogenic potential of ex vivo expanded endothelial progenitor cells (EPCs) in a rabbit model of hindlimb ischemia. Methods: Rabbit peripheral blood EPCs were cultured and transfected with mammalian expression vector pcDNA3.1-eNOS containing full-length human eNOS gene. Ischemia was induced in the right hind limb of three groups of rabbits by ligation of the distal external iliac artery and excision of the common and superficial femoral arteries. In one group of animals, ten days after the surgery, autologous eNOS-EPCs were transplanted intramuscularly in the ischemic limb. Two other groups received an equivalent number of unmodified EPCs or phosphate buffered saline (PBS) respectively. Results: Two weeks after cell transplantation, the in vivo expression of eNOS was detected in limb tissue sections of eNOS-EPCs treated animals. Animals treated with eNOS-EPCs had a significant reduction in ischemic muscle necrosis and inflammation, augmentation in the capillary density (P< 0.05) and angiographic scores demonstrating distal arterial reconstitution and enhanced angiogenesis in comparison to animals transplanted with EPCs or PBS (P< 0.05). Conclusion: We conclude that modification of EPCs by eNOS constitutes an effective strategy to improve the efficacy of EPCs for therapeutic angiogenesis

Biosafety of citrate coated zerovalent iron nanoparticles for Magnetic Resonance Angiography

Though nanoparticles are being used for several biomedical applications, the safety of the same is still a concern. It is very routine procedure to check the preliminary safety aspects of the particles intended for in vivo applications. The major tests include how the material reacts to a normal cell, how it behaves with the blood cells and also whether any lysis take place in the presence of these materials. Here we present these test data of two novel nanomaterials designed for its use as contrast agent for magnetic resonance imaging and a multimodal contrast agent for targeted liver imaging. On proving the biosafety, the materials were tested for Magnetic Resonance Angiography using normal rats as model. The data of the same were clear identification of the prominent vascular structures and is included as the colour coded MRI image. Lateral and oblique view data are also presented for visualizing other major blood vessels

Near infrared-emitting multimodal nanosystem for in vitro magnetic hyperthermia of hepatocellular carcinoma and dual imaging of in vivo liver fibrosis

Abstract Prolonged usage of traditional nanomaterials in the biological field has posed several short- and long-term toxicity issues. Over the past few years, smart nanomaterials (SNs) with controlled physical, chemical, and biological features have been synthesized in an effort to allay these challenges. The current study seeks to develop theranostic SNs based on iron oxide to enable simultaneous magnetic hyperthermia and magnetic resonance imaging (MRI), for chronic liver damage like liver fibrosis which is a major risk factor for hepatocellular carcinoma. To accomplish this, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared, coated with a biocompatible and naturally occurring polysaccharide, alginate. The resultant material, ASPIONs were evaluated in terms of physicochemical, magnetic and biological properties. A hydrodynamic diameter of 40 nm and a transverse proton relaxation rate of 117.84 mM−1 s−1 pronounces the use of ASPIONs as an efficient MRI contrast agent. In the presence of alternating current of 300 A, ASPIONs could elevate the temperature to 45 °C or more, with the possibility of hyperthermia based therapeutic approach. Magnetic therapeutic and imaging potential of ASPIONs were further evaluated respectively in vitro and in vivo in HepG2 carcinoma cells and animal models of liver fibrosis, respectively. Finally, to introduce dual imaging capability along with magnetic properties, ASPIONs were conjugated with near infrared (NIR) dye Atto 700 and evaluated its optical imaging efficiency in animal model of liver fibrosis. Histological analysis further confirmed the liver targeting efficacy of the developed SNs for Magnetic theranostics and optical imaging as well as proved its short-term safety, in vivo

Preclinical evaluation of hydrogel sealed fluropassivated indigenous vascular prosthesis

Background & objectives: Polyethylene terephthalate (PET) graft, designed and developed at our institute for vascular reconstruction, is porous to promote optimal incorporation and neointima formation, requiring pre-clotting or biomodification by sealing the pores before implantation. The objective of this study was to characterize, test and perform preclinical evaluation of hydrogel (alginate dialdehyde cross-linked gelatin) sealed fluoropassivated PET vascular prosthesis in pig model, so as to avoid pre-clotting, for its safety and efficacy before employing the indigenous and less expensive graft for clinical use. Methods: Hydrogel sealed, fluoropassivated PET vascular prosthesis were tested for haemocompatibility and toxicity followed by small animal toxicology tests and in vivo experiments in pigs receiving implantation at thoracic aorta. All 33 animals received test as well as control grafts with a plan for phased explantation at 2, 12 and 26 weeks. All animals underwent completion angiogram at the end of procedure as well as before graft explantation. Results: Haemocompatibility tests for haemolysis and toxicity tests showed no adverse events in tested mice and rabbits. Completion angiogram showed intact anastamosis and patent graft in each animal in post-operative period and at explantation. Gross and histopathological examination showed well-encapsulated grafts, clean glistening neointima and no evidence of thrombus in both test and control grafts. Interpretation & conclusions: Hydrogel sealed, fluoropassivated PET vascular prosthesis was found non-toxic, haemocompatible and remained patent in in vivo studies at planned intervals

Identifying the Best Machine Learning Algorithms for Brain Tumor Segmentation, Progression Assessment, and Overall Survival Prediction in the BRATS Challenge

Gliomas are the most common primary brain malignancies, with different degrees of aggressiveness, variable prognosis and various heterogeneous histologic sub-regions, i.e., peritumoral edematous/invaded tissue, necrotic core, active and non-enhancing core. This intrinsic heterogeneity is also portrayed in their radio-phenotype, as their sub-regions are depicted by varying intensity profiles disseminated across multi-parametric magnetic resonance imaging (mpMRI) scans, reflecting varying biological properties. Their heterogeneous shape, extent, and location are some of the factors that make these tumors difficult to resect, and in some cases inoperable. The amount of resected tumor is a factor also considered in longitudinal scans, when evaluating the apparent tumor for potential diagnosis of progression. Furthermore, there is mounting evidence that accurate segmentation of the various tumor sub-regions can offer the basis for quantitative image analysis towards prediction of patient overall survival. This study assesses the state-of-the-art machine learning (ML) methods used for brain tumor image analysis in mpMRI scans, during the last seven instances of the International Brain Tumor Segmentation (BraTS) challenge, i.e., 2012-2018. Specifically, we focus on i) evaluating segmentations of the various glioma sub-regions in pre-operative mpMRI scans, ii) assessing potential tumor progression by virtue of longitudinal growth of tumor sub-regions, beyond use of the RECIST/RANO criteria, and iii) predicting the overall survival from pre-operative mpMRI scans of patients that underwent gross total resection. Finally, we investigate the challenge of identifying the best ML algorithms for each of these tasks, considering that apart from being diverse on each instance of the challenge, the multi-institutional mpMRI BraTS dataset has also been a continuously evolving/growing dataset