49 research outputs found

    In Vitro and in Vivo Enhancement of Antitumoral Activity of Liposomal Antisense Oligonucleotides by Cineole as a Chemical Penetration Enhancer

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    Cellular uptake and cytoplasmic release of liposomal antisense oligonucleotides (AsODNs), which can act as rate-limiting steps, are still remained to be completely optimized. Here, the possibility of enhancing such processes at cellular and animal levels by cineole, as a penetration enhancer, was investigated. A cationic nanoliposome containing an AsODN against PKC-α and a cineole-containing nanoliposome were prepared and characterized. The effect of nanoliposomal cineole on sequence-specific cytotoxicity of nanoliposomal AsODN against A549, was studied in vitro (MTT, flow cytometry, fluorescence microscopy, and real time PCR) and in vivo (xenograft lung tumor in nude mice) using different concentrations and treatment times. Results showed specific cytotoxicity of nanoliposomal AsODN was increased significantly from 11 to 25 when A549 cells were exposed to 10 μg/mL cineole for 1 or 4 hours. This inhibitory effect was further increased to about 40 when the concentration was increased to 40 μg/mL for 1 hour. In animal studies, cineole significantly decreased the tumor volume (about 75) and increased its doubling time from 13 days to 31 days. A linear relationship exists between cineole concentration and its enhancement effects. Finally it was concluded that cineole, and possibly other membrane fluidizers, can improve nanoliposomal gene therapy at cellular and animal levels. © 2015 Hamid Reza Moghimi et al

    A Mathematical Model to Investigate Heat Transfer in Footwear during Walking and Jogging

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    Foot temperature during activities of daily living affects the human performance and well-being. Footwear thermal characteristics affect the foot temperature inside the shoe during activities of daily living. The temperate at the sole of the foot (plantar temperature) is influenced by different thermal properties such as heat capacity, heat diffusivity, and thermal conductivity of the shoe sole in addition to its mechanical properties. Hence the purpose of this study was to propose a method to allow investigating the effect of footwear thermal characteristics on the foot temperature during activities of daily living, like walking or jogging. The transient heat transfer between the foot and the ground was studied to drive the governing equation for heat transfer modelling in footwear and to predict foot sole temperature during walking, and jogging. Different thermo-mechanical properties of shoe sole, as well as geometrical parameters, were investigated. The proposed model showed to be able to adequately predict the plantar temperature at the ball of the foot when compared to the results from experimental measurements. Finally, using the proposed method, the thermal behaviour of two different shoes with two different sole materials EVA08 and EVA12 were compared. It was shown that heat capacity as compared to the thermal conductivity of the shoe sole is more effective in reducing the plantar temperature increase in short term. The proposed method proved to be able to accurately predict the thermal behaviour of shoes and can provide a tool to predict footwear thermal comfort

    A novel computational approach to combine the optical and thermal modelling of Linear Fresnel Collectors using the finite volume method

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    A computational approach is presented, which uses the finite volume (FV) method in the Computational Fluid Dynamics (CFD) solver ANSYS Fluent to conduct the ray tracing required to quantify the optical performance of a line concentration Concentrated Solar Power (CSP) receiver, as well as the conjugate heat transfer modelling required to estimate the thermal efficiency of such a receiver. A Linear Fresnel Collector (LFC) implementation is used to illustrate the approach. It is shown that the Discrete Ordinates method can provide an accurate solution to the Radiative Transfer Equation (RTE) if the shortcomings of its solution are resolved appropriately in the FV CFD solver. The shortcomings are due to false scattering and the so-called ray effect inherent in the FV solution. The approach is first evaluated for a 2-D test case involving oblique collimated radiation and then for a more complex 2-D LFC optical domain based on the FRESDEMO project. For the latter, results are compared with and validated against those obtained with the Monte Carlo ray tracer, SolTrace. The outcome of the FV ray tracing in the LFC optical domain is mapped as a non-uniform heat flux distribution in the 3-D cavity receiver domain and this distribution is included in the FV conjugate heat transfer CFD model as a volumetric source. The result of this latter model is the determination of the heat transferred to the heat transfer fluid running in the collector tubes, thereby providing an estimation of the overall thermal efficiency. To evaluate the effectiveness of the phased approach in terms of accuracy and computational cost, the novel 2-D:3-D phased approach is compared with results of a fully integrated, but expensive 3-D optical and thermal model. It is shown that the less expensive model provides similar results and hence a large cost saving. The novel approach also provides the benefit of working in one simulation environment, i.e. ANSYS Workbench, where optimisation studies can be carried out to maximise the performance of linear CSP reflector layout and receiver configurations.University of Pretoria (South Africa) and the South African National Research Foundation (DST-NRF Solar Spoke).http://www.elsevier.com/locate/solener2016-06-30hb201

    A novel computational approach to the combine optical and thermal modelling of a linear fresnel collector receiver

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    Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.A computational approach is presented that uses the finite volume (FV) method in the Computational Fluid Dynamics (CFD) solver ANSYS Fluent to perform both the ray tracing required to quantify the optical performance of a line-concentration Linear Fresnel Collector (LFC) receiver, as well as the conjugate heat transfer modelling required to estimate the thermal efficiency of such a receiver. It is shown that the Discrete Ordinates method can provide an accurate solution of the Radiative Transfer Equation (RTE) if the shortcomings of its solution are addressed appropriately in the FV CFD solver. This approach is evaluated for a 2-D sample test case that includes a 2-D LFC optical domain of which the results are compared to those obtained with the Monte Carlo ray tracer, SolTrace. The outcome of the FV ray tracing in the LFC optical domain is mapped as a non-uniform heat flux distribution in the 3-D cavity receiver domain and this distribution is included in the FV conjugate heat transfer CFD model as a volumetric resource. The result of this latter model is the determination of the heat transferred to the heat transfer fluid running in the collector tubes, thereby providing an estimation of the overall thermal efficiency. To evaluate the effectiveness of the phased approach, the 2-D:3-D approach is compared to results of a fully integrated, but expensive, 3-D optical and thermal model. It is shown that the less expensive model provides similar results and that it provides the benefit of working in one simulation environment, i.e., ANSYS Workbench, where additionally optimization studies can be performed in future work.dc201

    Optimization of a trapezoidal cavity absorber for the Linear Fresnel Reflector

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    To increase the efficiency of Concentrated Solar Power (CSP) plants, the use of optimization methods is a current topic of research. This paper focuses on applying an integrated optimization technology to a solar thermal application, more specifically for the optimization of a trapezoidal cavity absorber of an LFR (Linear Fresnel Reflector), also called a Linear Fresnel Collector (LFC), CSP plant. LFR technology has been developed since the 1960s, and while large improvements in efficiencies have been made, there is still room for improvement. Once such area is in the receiver design where the optimal cavity shape, coatings, insulation thickness, absorber pipe selection, layout and spacing always need to be determined for a specific application. This paper uses a commercial tool to find an optimal design for a set of operating conditions. The objective functions that are used to judge the performance of a 2-D cavity are the combined heat loss through convection, conduction and radiation, as well as a wind resistance area. In this paper the effect of absorbed irradiation is introduced in the form of an outer surface of pipe temperature. Seven geometrical parameters are used as design variables. Based on a sample set requiring 79 CFD simulations, a global utopia point is found that minimizes both objectives. The most sensitive parameters were found to be the top insulation thickness and the cavity depth. Based on the results, the Multi-Objective Genetic Algorithm (MOGA) as contained in ANSYS DesignXplorer is shown to be effective in finding candidate optimal designs as well as the utopia point.University of Pretoria, South Africa, the South African National Research Foundation, as well as the Solar Spoke of the South African Department of Trade and Industry.http://www.elsevier.com/locate/solener2016-09-30hb201

    SLE(κ,ρ\kappa,\rho)and Boundary Coulomb Gas

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    We consider the coulomb gas model on the upper half plane with different boundary conditions, namely Drichlet, Neuman and mixed. We related this model to SLE(κ,ρ\kappa,\rho) theories. We derive a set of conditions connecting the total charge of the coulomb gas, the boundary charges, the parameters κ\kappa and ρ\rho. Also we study a free fermion theory in presence of a boundary and show with the same methods that it would lead to logarithmic boundary changing operators.Comment: 10 pages, no figur

    Abelian Sandpile Model: a Conformal Field Theory Point of View

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    In this paper we derive the scaling fields in c=2c=-2 conformal field theory associated with weakly allowed clusters in abelian sandpile model and show a direct relation between the two models.Comment: 9 pages, 2 figure

    Finite‐volume ray tracing using Computational Fluid Dynamics in linear focus CSP applications

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    The modelling of solar irradiation in concentrated solar power (CSP) applications is traditionally done with ray-tracing methods, e.g. the Monte Carlo method. For the evaluation of CSP receivers, the results from ray-tracing codes are typically used to provide boundary conditions to Computational Fluid Dynamics (CFD) codes for the solution of conjugate heat transfer in the receivers. There are both advantages and disadvantages to using separate software for the irradiation and heat transfer modelling. For traditional ray-tracing methods, advantages are the cost-effectiveness of the Monte Carlo method in modelling reflections from specular surfaces; the ability to statistically assign a sun shape to the rays; the statistical treatment of reflectivity and optical errors (e.g. surface slope errors), to name a few. When considering a complex mirror field and a complex receiver with secondary reflective surfaces, especially with selective coatings to enhance absorption and limit re-radiation losses, standard ray tracers may be limited in specifying emissivity and absorptivity, which are both specular and temperature dependent, and are hence not suitable as radiation analysis tool. This type of scenario can be modelled accurately using CFD, through the finite volume (FV) treatment of the radiative transfer equation (RTE) and a banded spectrum approach at an increased computational cost. This paper evaluates the use of CFD in the form of the commercial CFD code ANSYS Fluent v15 and v16 to model the reflection, transmission and absorption of solar irradiation from diffuse and specular surfaces found in linear CSP applications. 2-D CFD solutions were considered, i.e. line concentration. To illustrate and validate the method, two sources were used. The first source was test cases from literature with published solutions and the second a combined modelling approach where solutions were obtained using both FV and ray tracing (with SolTrace). For all the test cases, good agreement was found when suitable modelling settings were used to limit both ray-effect and false scattering errors.The University of Pretoria (South Africa) and the South African National Research Foundation (DST-NRF Solar Spoke).http://www.elsevier.com/locate/apenergy2017-12-31hb2017Mechanical and Aeronautical Engineerin

    Survival analysis in gastric cancer: A multi-center study among Iranian patients

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    Background: Gastric cancer (GC) has been considered as the 5th most common type of cancer and the third leading cause of cancer-associated death worldwide. The aim of this historical cohort study was to evaluate the survival predictors for all patients with GC using the Cox proportional hazards, extended Cox, and gamma-frailty models. Methods: This historical cohort study was performed according to documents of 1695 individuals having GC referred to three medical centers in Iran from 2001 to 2018. First, most significant prognostic risk factors on survival were selected, Cox proportional hazards, extended Cox, gamma-frailty models were applied to evaluate the effects of the risk factors, and then these models were compared with the Akaike information criterion. Results: The age of patients, body mass index (BMI), tumor size, type of treatment and grade of the tumor increased the hazard rate (HR) of GC patients in both the Cox and frailty models (P < 0.05). Also, the size of the tumor and BMI were considered as time-varying variables in the extended Cox model. Moreover, the frailty model showed that there is at least an unknown factor, genetic or environmental factors, in the model that is not measured (P < 0.05). Conclusions: Some prognostic factors, including age, tumor size, the grade of the tumor, type of treatment and BMI, were regarded as indispensable predictors in patients of GC. Frailty model revealed that there are unknown or latent factors, genetic and environmental factors, resulting in the biased estimates of the regression coefficients. © 2020 The Author(s)

    Intelligent web-phishing detection and protection scheme using integrated features of Images, frames and text

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    A phishing attack is one of the most significant problems faced by online users because of its enormous effect on the online activities performed. In recent years, phishing attacks continue to escalate in fre- quency, severity and impact. Several solutions, using various methodologies, have been proposed in the literature to counter the web-phishing threats. Notwithstanding, the existing technology cannot detect the new phishing attacks accurately due to the insufficient integration of features of the text, image and frame in the evaluation process. The use of related features of images, frames and text of legitimate and non-legitimate websites and associated artificial intelligence algorithms to develop an integrated method to address these together. This paper presents an Adaptive Neuro-Fuzzy Inference System (ANFIS) based robust scheme using the integrated features of the text, images and frames for web-phishing detection and protection. The proposed solution achieves 98.3% accuracies. To our best knowledge, this is the first work that considers the best-integrated text, image and frame feature based solution for phishing detection scheme
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