Empirical models for the nonlinear rocking response of shallow foundations

This paper aims to introduce simple empirical models to describe the nonlinear behavior of shallow foundations under rocking vibration. The model is developed based on parametric numerical investigations of rectangular surface footings on homogenous dense dry sand, taking advantage of a nonlinear macro-element model verified based on a set of experimental results. The proposed empirical expressions include the moment-rotation backbone curve, stiffness degradation and equivalent damping ratio as well as the correlation of the foundation settlements with cumulated rotations. These expressions are provided mainly as a function of the rotation, static factor of safety and aspect ratio of foundation. Similar to previous researches, the uplift reference rotation was introduced as a normalization parameter for the new closed-form expressions to be expressed in a non-dimensional form, whenever possible. The proposed approach aimed to be simple, in order to minimize the dependence on the variable parameters, and to provide physically sound selections for engineering applications

A Hybrid 3D Colon Segmentation Method Using Modified Geometric Deformable Models

Introduction: Nowadays virtual colonoscopy has become a reliable and efficient method of detecting primary stages of colon cancer such as polyp detection. One of the most important and crucial stages of virtual colonoscopy is colon segmentation because an incorrect segmentation may lead to a misdiagnosis.  Materials and Methods: In this work, a hybrid method based on Geometric Deformable Models (GDM) in combination with an advanced region growing and thresholding methods is proposed. GDM are found to be an attractive tool for structural based image segmentation particularly for extracting the objects with complicated topology. There are two main parameters influencing the overall performance of GDM algorithm; the distance between the initial contour and the actual object’s contours and secondly the stopping term which controls the deformation. To overcome these limitations, a two stage hybrid based segmentation method is suggested to extract the rough but precise initial contours at the first stage of the segmentation. The extracted boundaries are smoothed and improved using a modified GDM algorithm by improving the stopping terms of the algorithm based on the gradient value of image voxels. Results: The proposed algorithm was implemented on forty data sets each containing 400-480 slices. The results show an improvement in the accuracy and smoothness of the extracted boundaries. The improvement obtained for the accuracy of segmentation is about 6% in comparison to the one achieved by the methods based on thresholding and region growing only. Discussion and Conclusion: The extracted contours using modified GDM are smoother and finer. The improvement achieved in this work on the performance of stopping function of GDM model together with applying two stage segmentation of boundaries have resulted in a great improvement on the computational efficiency of GDM algorithm while making smoother and finer colon borders

Alleviating the toxicity concerns of antibacterial cinnamon‐polycaprolactone biomaterials for healthcare‐related biomedical applications

Abstract Fibrous constructs with incorporated cinnamon‐extract have previously been shown to have potent antifungal abilities. The question remains to whether these constructs are useful in the prevention of bacterial infections in fiber form and what the antimicrobial effects means in terms of toxicity to the native physiological cells. In this work, cinnamon extract containing poly (ε‐caprolactone) (PCL) fibers were successfully manufactured by pressurized gyration and had an average size of ∼2 μm. Cinnamon extract containing PCL fibers were tested against Escherichia coli, Staphylococcus aureus, Methicillin resistant staphylococcus aureus, and Enterococcus faecalis bacterial species to assess their antibacterial capacity; it was found that these fibers were able to reduce viable cell numbers of the bacterial species up to two orders of magnitude lower than the control group. The results of the antibacterial tests were assessed by scanning electron microscopy (SEM). The constructs were also tested under indirect MTT tests where they showed little to no toxicity, similar to the control groups. Additionally, cell viability fluorescent imaging displayed no significant toxicity issues with the fibers, even at their highest tested concentration. Here we present a viable method for the production the non‐toxic and naturally abundant cinnamon extracted fibers for numerous biomedical applications