11351 research outputs found
Sort by
Preparation and characterization of chitosan-hydroxyapatite nanoparticles for gene therapy
No full textRecently, in pharmaceutical research and industry scientists widely have used polysaccharides and other cationic polymer which is one of the most extensive studies in the field of non-viral DNA carriers for gene delivery and therapy. As a purpose of present study variations of the final solution pH values and filtration were examined for their effects on the particle size and the tendency of particle formation. Chitosan nanoparticles were prepared based on the ionic gelatin of chitosan which hydroxyapatite will adsorb onto the chitosan nanoparticles to form complexes of chitosan and hydroxyapatite. The resulting nanoparticles had a size and positive electrical charge, which vary depending on the formulation conditions. The physicochemical properties of the nanoparticles were determined by scanning electron microscope (SEM). Besides of that, element and chemical characterization of samples were assessed by Energy-dispersive X-ray spectroscopy (EDX). The data revealed that the chitosan/DNA nanoparticles were successfully prepared with a nano size range. Obtained complexes could be loaded by variants of DNA for further use in gene delivery applications
Grayscale-image encryption using Random Hill Cipher over SLn(F) associated with Discrete Wavelet Transformation
Get PDFImage data are highly sensitive and prone to incidental decoding by intruders. The security of image data in an insecure network is therefore a major issue. In this paper, we have presented a novel approach for grayscale-image encryption and decryption using Random Hill cipher over SLn(F) associated with discrete wavelet transformation. Earlier techniques for encryption and decryption of image data discussed missing the keys, but in this approach, both the keys and the arrangement of RHC are emphasized. Additionally, keys multiplication side (pre or post) over a grayscale-image data matrix also inevitable to know, to correctly decrypt the encrypted image data. In proposed approach, consider keys from special linear group over field F. The key space of the whole cryptosystem is exorbitant. We have presented a computer simulation with a standard examples and the results is given to analyze the robustness of the proposed technique. Security analysis and detailed comparison among earlier developed techniques with proposed approach are also discussed for the robustness of the technique
Physically-Realizable Uniform Temperature Boundary Condition Specification on a Wall of an Enclosure: Part II – Problem Solution
Get PDFTemperature measurements along one side of the rectangular plate showed severe temperature non-uniformity along one side of a wall of a cubical experimental apparatus where the uniform temperature was physically desired. Despite proper planning and analyses, this non-uniformity was high enough that a benchmark study could not be carried out to the desired accuracy of about one percent error. This paper presents and extends analyses made previously based on the modifications to the original design of the apparatus to reduce the temperature non-uniformity on the wall by adding an auxiliary heater around a wall where the uniform temperature was desired. A detailed mathematical analysis shows significant reduction in temperature non-uniformity from about four percent (based on the initial design) to less than one percent (for the modified design). By examining the temperature difference between two locations on the plate, the predicted temperature difference obtained through mathematical analyses show excellent agreement with the measured temperature difference. The temperature non-uniformity along the boundary of a wall was reduced to less than one percent of the overall temperature difference
The Onset of Stationary and Oscillatory Convection in a Horizontal Porous Layer Saturated with Viscoelastic Liquid Heated and Soluted From Below: Effect of Anisotropy
Get PDFThe onset of double diffusive stationary and oscillatory convection in a viscoelastic Oldroyd type fluid saturated in an anisotropic porous layer heated and soluted from below is studied. The flow is governed by the extended Darcy model for Oldroyd fluid. Stability analysis based on the method of perturbations of infinitesimal amplitude is performed using the normal mode technique. The analysis examines the effect of the Darcy Rayleigh number, the solutal Darcy the Rayleigh number, the relaxation time, the retardation time and the Lewis number. Important conclusions include the destabilizing effect of the relaxation time, the Darcy Rayleigh number and the Lewis number and the stabilizing effect of the solutal Darcy Rayleigh number, the retardation time and anisotropy parameter. Some of the results are generalization of the previous findings for isotropic porous medium
The Two-Phase Arterial Blood Flow with or without a Catheter and in the Presence of a Single or Multi Stenosis
Get PDFWe consider the problem of blood flow in an artery with or without a catheter and in the presence of single or multi stenosis whose shape is based on the available experimental data for the stenosis in a human’s artery. The presence of stenosis in the artery, which locally narrows portion of the artery, can be a result of fatty materials such as cholesterol in the blood. The use of catheter is important as a standard tool for diagnosis and treatment in patience whose blood flow passage in the artery is affected adversely by the presence of the stenosis within the artery. The blood flow in the arterial tube is represented by a two-phase model composing a suspension of red cells in plasma. The governing equations for both fluid (plasma) and particles (red cells) are solved subject to reasonable modeling and approximations. The important quantities such as blood velocity, blood pressure gradient, impedance (blood flow resistance), wall shear stress and its surface integrated force are computed in the presence or absence of the catheter, and, in particular, effects of the stenosis, size of the catheter’s radius and the hematocrit due to the red cells-plasma combination of the blood flow are determined
US remittances to the Caribbean, Jamaica and Trinidad & Tobago
No full textA remittance is part of an employee\u27s wages or salary that is sent back home. Remittances not only help the workers\u27 family members, but also help the home countries to strengthen their balance of payments. Remittances are remuneration to employees from the economy in which they work, and thus they contribute to both the gross domestic product (GDP) and the gross national income (GNI) of that economy. Because of their stability and dependability, remittances have become a permanent fixture of governments\u27 financial revenues. The primary objective of this research is to determine whether foreign nationals make a significant contribution to the level of remittances and what some of the determinants are. We utilize three models to test whether the categories of foreign nationals - immigrants admitted; persons naturalized; and non-immigrants admitted as temporary workers, exchange visitors and intra-company transferees - send significant amounts of remittances. In this work, we look at the flow of remittances during the 1982-2001 period from the United States to the Caribbean region, Jamaica, and Trinidad and Tobago. The results indicate that the number of immigrants admitted , persons naturalized and non-immigrants admitted as temporary workers, exchange visitors and intra-company transferees , together with the exchange rate , the Hispanic unemployment rate and the median income of Hispanic families , are significant determinants in the size of remittances. When the results are extrapolated, the number of immigrants admitted produces the maximum remittance flow to Jamaica. The number of persons naturalized is important to the total remittances for the overall Caribbean region. The non-immigrant temporary worker group is the largest single source of remittances. This group may potentially send US$15 billion to Trinidad and Tobago. © 2012 The Authors International Migration © 2012 IOM
Functional identification of valerena-1,10-diene synthase, a terpene synthase catalyzing a unique chemical cascade in the biosynthesis of biologically active sesquiterpenes in Valeriana officinalis
No full textBackground: Therapeutic values of Valeriana officinalis have been associated with sesquiterpenes whose biosynthetic origins have remained enigmatic. Results: A cyclobutenyl intermediate in the catalytic cascade of valerena-1,10-diene synthase is reported. Conclusion: A new class of sesquiterpene synthases for the biosynthesis of sesquiterpenes harboring isobutenyl functional groups is proposed. Significance: Similar catalytic mechanisms from evolutionarily diverse organisms are proposed and portend sources for sesquiterpene diversity. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc
Scaffolds for tissue engineering
No full textThe aim of tissue engineering is to develop cell, construct, and living system technologies to restore the structures and functions of damaged or degenerated tissues. Surgical strategies that have evolved to deal with tissue loss include organ transplantation from one individual to another, tissue transfer from a healthy site to an affected site in the same individual, and replacement of tissue functions with synthetic material devices. All of these strategies have limitations. Organ transplantation is not always feasible as the number of organ donors is far less than the number of patients waiting for organ transplantation. The complications of immuno-suppressive agents are also trouble for the organ recipients. Tissue engineering (TE) seeks to provide a new solution to tissue loss. Scaffolds with porous microstructures are commonly used in TE. This chapter reviews and reports the TE strategy, requirements of scaffolds in TE, as well as different biomaterials that are often used to fabricate tissue engineering scaffolds
Composite scaffolds based on poly(caprolactone) and Chitosan for bone tissue regeneration
No full textThe scaffold material and architecture of the scaffold can affect cell seeding and tissue growth both in vitro and in vivo in the engineering of various tissues. Biocompatible and biodegradable polymers can be used to produce scaffolds in tissue engineering. Poly(caprolactone) PCL and Chitosan are promising biodegradable polymers to fabricate tissue engineering scaffolds. Hydroxyapatite (HA) is osetoconductive and is being used for bone replacement. The composite scaffolds made of these two materials have great potential for bone tissue engineering. This paper reports the fabrication and characterization of three-dimensional, highly porous composite scaffolds produced from HA/PCL and HA/Chitosan. The scaffolds were produced using thermally induced phase separation (TIPS) technique. The structure and properties of composite scaffolds were investigated using various techniques. © 2013 American Scientific Publishers All rights reserved