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The fabrication and characterization of PCL/rice husk derived bioactive glass-ceramic composite scaffolds
No full textThe present study was conducted to fabricate a 3D scaffold using polycaprolactone (PCL) and silicate based bioactive glass-ceramic (R-SBgC). Different concentrations of R-SBgC prepared from rice husk ash (RHA) were combined with PCL to fabricate a composite scaffold using thermally induced phase separation (TIPS) method. The products were then characterized using SEM and EDX. The results demonstrated that R-SBgC in PCL matrix produced a bioactive material which has highly porous structure with interconnected porosities. There appears to be a relationship between the increase in R-SBgC concentration and increased material density and compressive modulus; however, increasing R-SBgC concentration result in reduced scaffold porosity. In conclusion, it is possible to fabricate a PCL/bioactive glass-ceramic composite from processed rice husk. Varying the R-SBgC concentrations can control the properties of this material, which is useful in the development of the ideal scaffold intended for use as a bone substitute in nonload bearing sites. © 2014 Farnaz Naghizadeh et al
Effects of parameters on the fabrication of poly(caprolactone) electrospun membrane using electrospinning technique
No full textDue to the ability to fabricate fibrous scaffolds with micro and nano-scale properties, electrospinning technique has received much interest. Poly(caprolactone) (PCL) fibrous scaffolds with micro and nano-scale fibers and surface-porous fibers have not been explicitly investigated. In this study, the results of modulating the factors on processing route on fibrous scaffold morphology were investigated. 10% w/v and 13% w/v PCL in dichloromethane (DCM) or chloroform was used at different flow rate and applied voltage. The result showed 13% w/v PCL/chloroform produced better fibers with porous bimodal distribution fiber sizes. The porous fibrous scaffolds had two different ranges of fiber diameters. Average fiber diameter in the higher range was 4 μm to 9 μm while average fiber diameter in the lower range was 400 nm
Privacy-aware display strategy in friend search
No full textA large body of work has addressed preserving users\u27 relationship privacy in sharing online social network (OSN) data with third-parties. However, the disclosure of relationship privacy in using the friend search engines on OSNs has not been given sufficient attention. In this paper, we consider that users indicate different comfort levels to share their friendships in OSNs by limiting the number of their friends returned in response to queries through the friend search engine. We propose a new attack model where an attacker attempts to infer more friendship information based on the friendships detected in the query results. Additionally, we define the model of (β, k)-inference privacy preservation which ensures to safely display k friends of individual users in response to queries. We also propose a display strategy which balances the tradeoff between preserving users\u27 friendship privacy and maintaining the sociality of OSNs. From the experimental results, we can see the effectiveness of our strategy in handling such a tradeoff. © 2014 IEEE
Effects of Al-Mn co-doping on magnetic properties of semiconducting oxide thin films
No full textWe conducted an experimental investigation of the structural and magnetic properties of Al-Mn-doped ZrO2 and ZnO thin films. It was found that, even though additional Al doping does not substantially enhance ferromagnetism (FM), it influences surface magnetism by enhancing it. Increase of the Al concentration slightly improves the overall magnetization of the Al-Mn-doped ZrO2 sample, however, this effect is also accompanied by a deterioration of the crystallinity of the sample. On the other hand, we found that by co-doping the Mn-doped ZnO samples with Al, the result is a significant increase of the magnetic moment. Apart from the surface effects, the data clearly indicate that the observed FM originates from defects. Our results confirm that co-doping with Al can be an efficient way to enhance magnetism and control the distribution of defects for certain transition-metal-doped semiconducting oxides
Perceived racism and suicide ideation: Mediating role of depression but moderating role of religiosity among African American adults
No full textSuicide is a public health problem for African Americans who are young and of working age. The purpose of this study was to examine mediated and moderated effects of perceived racism on suicide ideation in a community sample of 236 African American men and women. Measures of suicide ideation, depression symptoms, intrinsic/extrinsic religiosity, and perceived racism were administered. Perceived racial discrimination was directly and indirectly associated with suicide ideation. For participants who reported low levels of extrinsic religiosity, the mediated effect of perceived racism (via depression symptoms) was significant. These findings provide some insight into suicide vulnerability for specific subgroups of African Americans
Socioeconomic Status and Symptoms of Depression and Anxiety in African American College Students: The Mediating Role of Hopelessness
No full textFactors such as socioeconomic status (SES) and hopelessness, a dimension of cognitive vulnerability, have been associated with the onset of depression and anxiety pathology in primarily European American study samples. The purpose of this brief article was to examine a main effect of SES and mediating effect of hopelessness in relation to acute symptoms of depression and anxiety in African American college students. Vulnerability-stress theories suggest that cognitively vulnerable individuals are more likely to develop depressive symptoms than individuals without cognitive vulnerabilities. Participants were 133 African American college students who completed self-report measures of hopelessness and symptoms of depression and anxiety. Results revealed that the relationship between participants\u27 SES and participants\u27 symptoms of depression was partially mediated by self-reported hopelessness. The relationship between participants\u27 SES and anxiety symptoms was fully mediated by their level of hopelessness. However, the direction of the findings was unexpected in that higher SES was associated with increased symptoms of depression and anxiety and also increased hopelessness. Future research and considerations for intervention are briefly discussed. © The Author(s) 2013
The Generalized Laguerre Matrix Method or Solving Linear Differential-Difference Equations with Variable Coefficients
Get PDFIn this paper, a new and efficient approach based on the generalized Laguerre matrix method for numerical approximation of the linear differential-difference equations (DDEs) with variable coefficients is introduced. Explicit formulae which express the generalized Laguerre expansion coefficients for the moments of the derivatives of any differentiable function in terms of the original expansion coefficients of the function itself are given in the matrix form. In the scheme, by using this approach we reduce solving the linear differential equations to solving a system of linear algebraic equations, thus greatly simplify the problem. In addition, several numerical experiments are given to demonstrate the validity and applicability of the method
Application of the Extended G\u27/G-expansion Method to the Improved Eckhaus Equation
Get PDFIn this paper, the extended (G\u27/G)-expansion method is used to seek more general exact solutions of the improved Eckhaus equation and the (2+1)-dimensional improved Eckhaus equation. As a result, hyperbolic function solutions, trigonometric function solutions and rational function solutions with free parameters are obtained. When the parameters are taken as special values the solitary wave solutions are also derived from the traveling wave solutions. Moreover, it is shown that the proposed method is direct, effective and can be used for many other nonlinear evolution equations in mathematical physics
Existence of Solutions for Multi-Points Fractional Evolution Equations
Get PDFIn this paper we study an impulsive fractional evolution equation with nonlinear boundary conditions. Sufficient conditions for the existence and uniqueness of solutions are established. To illustrate our results, an example is presented
Isotopic Form of M-Rings
Get PDFThe aim of this work is to generalize the notion of isofields by presenting the notion of Misorings. A method for constructing new M-isorings is presented. It is proved that an M-isoring for which its isounit is the fixed point of its identity function is an M-ring. Two methods for constructing new M-rings are presented