Intravitreal tolerance of a new perfluorocarbon vitreous replacement, Multifluor APF-144

OBJECTIVE: To evaluate the intravitreal tolerance of a new perfluorocarbon vitreous replacement, Multifluor APF-144 (perfluorotetramethylcyclohexane). DESIGN: Ten New Zealand albino rabbits (one eye from each) underwent vitrectomy. The vitreous was replaced in five eyes with Multifluor APF-144 and in five eyes with saline (control group). OUTCOME MEASURES: Appearance on indirect ophthalmoscopy, electroretinography recordings before and 2, 4 and 8 weeks after vitrectomy, findings on electron and light microscopy at 8 weeks. RESULTS: Endophthalmitis did not develop in any of the eyes. There was no significant change in electroretinography values for the experimental eyes after vitrectomy. No evidence of retinal toxicity was found on light or electron microscopic examination. CONCLUSIONS: Multifluor APF-144 shows promise as a short-term postoperative retinal tamponading agent.     

A novel approach to predict shear strength of tilted angle connectors using artificial intelligence techniques

Shear connectors play a prominent role in the design of steel-concrete composite systems. The behavior of shear connectors is generally determined through conducting push-out tests. However, these tests are costly and require plenty of time. As an alternative approach, soft computing (SC) can be used to eliminate the need for conducting push-out tests. This study aims to investigate the application of artificial intelligence (AI) techniques, as sub-branches of SC methods, in the behavior prediction of an innovative type of C-shaped shear connectors, called Tilted Angle Connectors. For this purpose, several push-out tests are conducted on these connectors and the required data for the AI models are collected. Then, an adaptive neuro-fuzzy inference system (ANFIS) is developed to identify the most influencing parameters on the shear strength of the tilted angle connectors. Totally, six different models are created based on the ANFIS results. Finally, AI techniques such as an artificial neural network (ANN), an extreme learning machine (ELM), and another ANFIS are employed to predict the shear strength of the connectors in each of the six models. The results of the paper show that slip is the most influential factor in the shear strength of tilted connectors and after that, the inclination angle is the most effective one. Moreover, it is deducted that considering only four parameters in the predictive models is enough to have a very accurate prediction. It is also demonstrated that ELM needs less time and it can reach slightly better performance indices than those of ANN and ANFIS.

     

Transport of Gellan Gum Microbeads in Soil Columns of Various Grain Size Distributions

The transport of gellan gum microbeads as potential cell carriers was investigated in horizontal columns packed with different grain size classes of gravel (2–16 mm) and sand (0.25–2 mm). A suspension of microbeads was pulsed into each column for 6 h, followed by injection of water for 42 h. In general, the total amount of microbeads travelling across a given section of the column increased with injection time but decreased towards the column outlet, varying as a direct function of grain size. The results of this study demonstrate the feasibility of the transport of gellan gum microbeads through medium sand to medium gravel across distances up to 110 cm.     

Copper/copper oxide nanoparticles synthesis using Stachys lavandulifolia and its antibacterial activity

Nanoparticles of copper/cuprous oxide (Cu/Cu₂ O) were successfully synthesised by a green chemistry route. The synthesis process was carried out using an extract of Stachys lavandulifolia as both reducing and capping agents with a facile procedure. The nanoparticles were characterised by different techniques including X‐ray diffraction, indicating that the synthesised sample comprised both copper and cuprous oxide entity. The nanoparticles had a mean size of 80 nm and represented an impressive bactericidal effect on Pseudomonas aeruginosa.Inspec keywords: copper, copper compounds, nanoparticles, nanofabrication, nanomedicine, antibacterial activity, X‐ray diffractionOther keywords: nanoparticles synthesis, Stachys lavandulifolia, antibacterial activity, green chemistry route, reducing agents, capping agents, X‐ray diffraction, bactericidal effect, Pseudomonas aeruginosa, Cu‐Cu₂ O     

Annotation-based access control for collaborative information spaces

Web 2.0 social platforms (e.g., Flickr, YouTube) and Collaborative Working Environments (e.g., Microsoft SharePoint, BSCW) provide Web-based collaborative information spaces which enable common users and/or professionals to work together and share their online resources. Most of these collaborative information spaces provide role-based or group-based, coarse-grained access control policies which cannot successfully cope with the requirements posed by massive and open collaboration. In this paper, we present an annotation-based access control (AnBAC) model supported by a Collaboration Vocabulary (CoVoc) as a more flexible and user-centric access control approach. Based on this, we developed two tools: Uncle-Share is a gadget that provides annotation-based access control and can be equipped with CoVoc for annotating collaborative relationships. Who-With-Whom uses CoVoc to visualize extended social networks in order to help users to select appropriate contacts to grant access to resources.     

Robust design optimization of electro-thermal microactuator using probabilistic methods

Micromachining of microelectromechanical systems which is similar to other fabrication processes has inherent variation that leads to uncertain dimensional and material properties. Methods for optimization under uncertainty analysis can be used to reduce microdevice sensitivity to these uncertainties in order to create a more robust design, thereby increasing reliability and yield. In this paper, approaches for uncertainty and sensitivity analysis, and robust optimization of an electro-thermal microactuator are applied to take into account the influence of dimensional and material property uncertainties on microactuator tip deflection. These uncertainties include variation of thickness, length and width of cold and hot arms, gap, Young modulus and thermal expansion coefficient. A simple and efficient uncertainty analysis method is performed by creating second-order metamodel through Box-Behnken design and Monte Carlo simulation. Also, the influence of uncertainties has been examined using direct Monte Carlo Simulation method. The results show that the standard deviations of tip deflection generated by these uncertainty analysis methods are very close to each other. Simulation results of tip deflection have been validated by a comparison with experimental results in literature. The analysis is performed at multiple input voltages to estimate uncertainty bands around the deflection curve. Experimental data fall within 95 % confidence boundary obtained by simulation results. Also, the sensitivity analysis results demonstrate that microactuator performance has been affected more by thermal expansion coefficient and microactuator gap uncertainties. Finally, approaches for robust optimization to achieve the optimal designs for microactuator are used. The proposed robust microactuators are less sensitive to uncertainties. For this goal, two methods including Genetic Algorithm and Non-dominated Sorting Genetic Algorithm are employed to find the robust designs for microactuator.     

Design of laminated composite structures for optimum fiber direction and layer thickness,using optimality criteria

In this study, two optimality criteria are presented for optimum design of composite laminates using finite element method. Thickness of the layers and fiber orientation angles in each finite element are considered as the design variables. It will be shown that the optimum design of composite laminates with varying fiber orientations and layers thicknesses may be found by using these optimality criteria in an efficient way, without performing the sensitivity analysis.     

Simultaneous Determination of Sodium, Potassium, Manganese and Bromine in Tea by Standard Addition Neutron Activation Analysis

Standard addition method was applied for neutron activation analysis of tea leaves. Four brands of tea leaves were analyzed for its Na, K, Mn, and Br contents by this method. The Na, K, Mn, and Br concentrations were found to be in the 90–120 μg/g, 1.8–2.1% w/w, 150–500 and 3–7 μg/g ranges, respectively. The extraction efficiency of these elements, during the infusion, was calculated by analysis of tea leaves before and after the infusion process. It was observed that about 90% of the Na, K, and Br elements were extracted to water during the infusion process. The drinking tea is a rich source of Mn (despite of an extraction efficiency of 50% for this element).     

Alkoxysilane modification of a Ti‐based catalyst system for ethylene dimerization: A step forward in enhancing productivity and selectivity

Alkoxysilanes were used as novel enhancing agents in the Ti‐based catalyst for the highly selective ethylene dimerization to butene‐1. The dimerization of ethylene was carried out using the homogeneous Ti(OBu)₄/THF/TEA/alkoxysilane catalyst system, where Ti(OBu)₄, THF (tetrahydrofuran), TEA (triethylaluminum), and alkoxysilane were used as catalyst, additive, activator, and modifier, respectively. The nature and concentration of alkoxysilanes on the dimerization rate, catalyst yield, by‐products production, and selectivity to butene‐1 were investigated in detail. It was found that the performance of alkoxysilanes assisted with the class of the Ti‐based catalyst system, developed in this work, has been furthered by high productivity and selectivity with respect to the bare catalyst system. It proved that alkoxysilanes could play an excellent improving role in the selective ethylene dimerization process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44615.     

Three-dimensional transient analysis of FGM cylindrical shell subjected to thermal and mechanical loading

In this article, transient analysis of functionally graded material (FGM) cylindrical shell subjected to thermomechanical load is performed. Mechanical and thermal properties of the shell are assumed to be graded in radial direction according to power law distribution. In the case of simply supported edge condition, problem is solved analytically using Fourier series expansions for stresses and displacements along the axial direction and state space technique along the radial direction and Laplace transformation technique for time domain. For other boundary conditions, we use a semianalytical method by applying differential quadrature method along the axial direction and the state space method along radial direction. Accuracy of this approach is validated by comparing the results with the results reported in the literature. Moreover, influence of edge boundary conditions, length to mid radius ratio, FGM direction and time on stresses, and displacements is studied.