The effect of magnesium content on in vitro bioactivity,biological behavior and antibacterial activity of sol–gel derived 58S bioactive glass

Bioactive glasses (BGs) have a great potential for bone replacement and regeneration in bone tissue engineering applications. In this research, first, sol–gel derived magnesium substituted 58?S BGs (MBGs) series composed of 60SiO₂–4P₂O₅-(36-x) CaO- xMgO, (x = 0; 1; 3; 5; 8 and 10?mol.%) were synthesized and stabilized at 700?°C to eliminate the nitrates and prevent the crystallization of MBGs. MgO was substituted for CaO in the BG formula up to 10?mol% and the effect of Mg concentration on in vitro bioactivity and cellular properties of the MBGs were investigated by immersing them in simulated body fluid (SBF) followed by structural characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques. The effects Mg on proliferation and differentiation of osteoblastic MC3T3-E1 cells were also evaluated by 3-(4,5dimethylthiazol-2-yl)??2,5-diphenyltetrazolium bromide (MTT) and alkaline phosphate (ALP) activity.Results revealed that magnesium-substituted 58?S BG with 5?mol% MgO (BG-5) had the highest formation rate of hydroxyapatite (HA) while substitution of 8?mol% and10 mol% MgO (BG-8 and BG-10) lowered the bioactivity. MTT and ALP results confirmed that the substitution of the MgO up to 5?mol% increased both proliferation and differentiation of MC3T3-E1 cells, while more substitution had a negative effect and resulted in a decrease of proliferation and differentiation in BG-8 and BG-10. The result of antibacterial test showed that MBGs exhibited antibacterial effect against methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Taken together, results suggest that, among all the synthesized MBGs, sample BG-5 is a promising candidate as multifunctional biomaterial for bone tissue engineering with maximum cell proliferation and ALP activity, good bioactivity and high antibacterial efficiency against MRSA bacteria. Eventually, the BG-5 is suggested to be used in segmental defects in rat model in vivo.     

Synthesis and in vitro assessment of novel water‐soluble dextran‐docetaxel conjugates as potential pH sensitive system for tumor‐targeted delivery

Docetaxel is a potent taxane agent mostly used in breast, lung, and prostate cancers. Its low water solubility is the major drawback that leads to use of Tween 80 as surfactant and ethanol as solvent in market formulation. But, these excipients cause severe hypersensitivity reactions. In this study, docetaxel was conjugated to biocompatible polymer, dextran 70 kDa, via a pH sensitive linker to enhance solubility and diminish the need of surfactants. Folic acid was also conjugated to dextran to provide targeted delivery. Synthesized conjugates were examined for solubility, hemo‐compatibility, stability, and cytotoxicity on MCF‐7 and MDA‐MB‐231 cell lines. Results showed about 1200‐fold enhancement in water solubility by dextran and 280‐fold by dextran‐folate conjugation. Conjugates released the drug in a pH‐dependent manner and faster hydrolysis was observed in pH 5.4 than physiological pH 7.4. Docetaxel‐dextran conjugates showed proper hemo‐compatibility and presented greater cytotoxicity than docetaxel solution. Higher cytotoxicity was seen in folate conjugated samples and the final conjugates targeted by folate would be suitable novel substitutions for currently marketed formulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45457.     

A reflection‐only method for characterizing PEC‐backed anisotropic materials using waveguide higher order modes

This paper presents a new reflection‐only set‐up for characterizing the properties of an anisotropic PEC‐backed materials. Albeit, the reflection‐only methods are established long ago, they are not elaborated appropriately for retrieving industrial anisotropic materials. In spite of other researches, this method is capable to determine tensors of both permittivity and permeability of an anisotropic PEC‐backed material. In contrast to similar researches, this method is mathematically simple and easy to implement. Tensors of epsilon and mu of PEC‐backed sample are characterized by rotating sample and measuring reflection coefficient in various configuration. Not measuring the transmission, in order to provide enough equations, the higher order mode of the waveguide is employed. A three‐port probe is designed for this goal and optimized to excite the TE₁₀ and TE₂₀ modes simultaneously. Good agreement of retrieved parameters from experimental measurements with those of actual ones shows the reliability of this set‐up for characterization of PEC‐backed anisotropic composites.     

Impact of heat,power and hydrogen generation on optimal placement and operation of fuel cell power plants

In this paper, a stochastic model is proposed for planning the location and operation of Fuel Cell Power Plants (FCPPs) as Combined Heat, power, and Hydrogen (CHPH) units. Total cost, emissions of FCPPs and substation, and voltage deviation are the objective functions to be minimized. Location and operation of FCPPs as CHPH are considered in this paper while their investment cost is not taken into account. In the proposed model, indeterminacy refers to electrical and thermal loads forecasting, pressure of oxygen and hydrogen, and the nominal temperature of FCPPs. In this method, scenarios are produced using roulette wheel mechanism and probability distribution function of input random variables. Using this method, the probabilistic problem is considered to be distributed as some scenarios and consequently probabilistic problem is considered as combination of some deterministic problems. Considering the nature of objective functions, the problem of locating and operating FCPPs as CHPH is considered as a mixed integer nonlinear problem. A Self Adaptive Charged System Search (SACSS) algorithm is employed for determining the best Pareto optimal set. Furthermore, a set of non-dominated solutions is saved in repository during simulation procedure. A 69-bus distributed system is used for verifying the beneficiary proposed method.     

Monitoring multivariate–attribute processes based on transformation techniques

Control charts are widely used in monitoring the quality of a product or a process. In most of the cases, quality of a product or a process can be characterized by two or more correlated quality characteristics. Many control charts have been proposed for monitoring multivariate or multi-attribute quality characteristics, separately, but sometimes the correlated variables and attribute quality characteristics represents the quality of a process. In this paper, the use of four transformation methods is proposed to monitor the multivariate–attribute processes. In the first one, the distribution of correlated variables and attribute quality characteristics are transformed to approximate multivariate normal distribution, and then the transformed data are monitored by multivariate control charts including T ² and MEWMA. Based on the second transformation method, the correlated variables and attribute quality characteristics are transformed, such that the correlation between the quality characteristics approaches to zero, then univariate control charts are used in monitoring the transformed data. In the third and fourth proposed methods, a combination of two transformation methods is used to make the quality characteristics independent and to transform them to normal distribution. The difference between the third and fourth method is the order of using the transformation techniques. The performance of the proposed methods is evaluated by using simulation studies in terms of average run length criterion. Finally, the proposed approach is applied to a real dataset.     

Stabilizing frequency weighted controller reduction approach

This note addresses the problem of instability in frequency weighted controller reduction methods based on similarity transformations. The aim is to reduce the complexity of the controllers derived by modern controller design packages for practical applications. For a given controller a framework is proposed that parameterizes a set of reduced controllers that preserve the stability of the closed loop system. Then based on this result a complementary algorithm to obtain a stabilizing stable reduced controller based on the two sided frequency weighted reduction method is presented. In addition, a sufficient condition for the existence of such a framework is derived.     

Multiple sperm tracking in microscopic videos using modified GM-PHD filter

This paper presents a method for simultaneous tracking of multiple sperms using modified Gaussian mixture probability hypothesis density (GM-PHD) filter. In order to track sperms with spurious motion, a modified model is presented to adapt the GM-PHD filter for nonlinear dynamic movement of sperms. Furthermore, the “pruning” step in the GM-PHD filter is modified to handle situations like occlusion or closely moving targets. Our experiments demonstrate more effectivity of the proposed method in terms of sperms’ occlusion handling and trajectory extraction compared to the conventional GM-PHD filter. In particular, the new method performs well in managing the labels of occluded sperms after separation and in tracking of temporarily disappeared sperms when they emerge again in the tracking space.     

Forecasting contractor's deviation from the client objectives in prequalification model using support vector regression

Contractor prequalification (CP) is a very complex decision-making process with nonlinearity, uncertainty and imprecision in inputs containing both subjective and objective data. The failure to perform CP can lead to large losses, delays or severe loss of project quality. Although the most reliable approach identified in the literature is currently artificial neural network (ANN), it has weaknesses that negatively affect CP. In this study, a new approach called support vector machines (SVM) has been used to forecast a contractor's deviation from a client's objectives. In order to test the model, CP for 250 virtual contractors was solved. The proposed model had a great generalization in linear, nonlinear, noisy and inductive environments. The Results showed that SVM could reliably perform even with a small amount of training data. Also when compared to ANN, SVM showed an overall better performance.     

Silver recovery from radiographic film processing effluents by hydrogen peroxide: Modeling and optimization using response surface methodology

The recovery of silver from X-ray film processing effluents by precipitation using hydrogen peroxide as the precipitating agent was studied. Response surface methodology (RSM) and central composite design (CCD) were applied to achieve optimum conditions. Linear, square and interactions effects between parameters to study of a second order polynomial equation were obtained. Optimum condition included the volume of H₂O₂ 0.8 ml/min, pH=5.5, ethylene glycol 9 ml in the experimental condition. In these conditions silver recovery percentage was predicted as 92.8%. The experiment was conducted in triplicate under optimized conditions. Silver recovery percentage and average of precipitate were obtained as 91.5% and 423.19mg, respectively, which were close to the predicted amount achieved by the model.