Effect of plate-like glass fillers on the mechanical properties of dental nanocomposites

In this study, glass flakes were incorporated into the spherical nanosilica component of the dental composites and its effect on the mechanical properties of these composites was investigated. To achieve a good interfacial adhesion between matrix resin and fillers, the particles were surface treated with a silane coupling agent (γ-MPS). Composites with different plate-like and spherical nanoparticle contents were prepared and their mechanical properties, including flexural strength, flexural modulus and fracture toughness were measured. The morphology of the particles and fracture surface of the composites were studied by SEM. The distribution of the flakes in the composite was also monitored using EDXA. Statistical analysis of the data was performed with ANOVA and the Tukey’s post hoc test was at a significance level of 0.05. The results showed that the flexural modulus and fracture toughness of specimens were improved with increasing the glass flake content up to 15 vol % which then declined upon further increase due to the stacking of the flakes on each other. A good interfacial adhesion was observed between matrix resin and particles in the SEM micrographs. The results of this study suggest that incorporation of glass flakes into the dental composites containing spherical nanosilica particles may enhance their mechanical properties.     

A modified method for image encryption based on chaotic map and genetic algorithm

Multimedia Tools and Applications - The security of digital data has been attending more than past, spatially image data security. In this study, a hybrid image encryption method has been proposed...     

Numerical simulation of the impact of polymer rheology on polymer injectivity using a multilevel local grid refinement method

Polymer injectivity is an important factor for evaluating the project economics of chemical flood, which is highly related to the polymer viscosity. Because the flow rate varies rapidly near injectors and significantly changes the polymer viscosity due to the non-Newtonian rheological behavior, the polymer viscosity near the wellbore is difficult to estimate accurately with the practical gridblock size in reservoir simulation. To reduce the impact of polymer rheology upon chemical EOR simulations, we used an efficient multilevel local grid refinement (LGR) method that provides a higher resolution of the flows in the near-wellbore region. An efficient numerical scheme was proposed to accurately solve the pressure equation and concentration equations on the multilevel grid for both homogeneous and heterogeneous reservoir cases. The block list and connections of the multilevel grid are generated via an efficient and extensible algorithm. Field case simulation results indicate that the proposed LGR is consistent with the analytical injectivity model and achieves the closest results to the full grid refinement, which considerably improves the accuracy of solutions compared with the original grid. In addition, the method was validated by comparing it with the LGR module of CMG_STARS. Besides polymer injectivity calculations, the LGR method is applicable for other problems in need of near-wellbore treatment, such as fractures near wells.     

Developing a Scaling Equation as a Function of Pressure and Temperature to Determine the Amount of Asphaltene Precipitation

A simple and applicable scaling equation as a function of pressure, temperature, molecular weight, dilution ratio (solvent), and weight percent of precipitated asphaltene has been developed. This equation can be used to determine the weight percent of precipitated asphaltene in the presence of difference precipitants (solvents) and the amount of solvent at onset point. Since increasing the pressure of crude oil decreases the amount of asphaltene precipitation, the effect of reservoir pressure has been taken into account in developing this equation. The results obtained by using this equation are substantially different and more accurate from other developed scaling equations for asphaltene precipitation. By considering the effect of reservoir pressure in developing the scaling equation and application of a genetic algorithm, the unknown parameters of the scaling equation are simultaneously and without any reservation obtained. The most important application of this unique equation is in the determination of critical point of asphaltene precipitation, known as onset point, and asphaltene precipitation in gas injection operations for enhanced oil recovery. The results predicted using the scaling equations are compared with the authors' experimental and literature precipitation data and it is shown that they are in good agreement with our experimental data. The scaling equation can be used in the design of gas-injected reservoir to prevent precipitation of the asphaltene aggregates in the reservoir.     

Effects of isomerism on near infrared properties of perylene bisimide derivatives

In this study, five different perylene bisimide derivatives are synthesized, four of which are structural isomers. The pigments are used to prepare corresponding paints and their ultraviolet–visible–near infrared (NIR) reflectance is investigated on two optically different substrates, namely high absorptive and high reflective substrates. These pigments are classified according to their NIR properties. They show substantial differences in NIR reflectance, transmittance, and absorbance despite their structural similarities. This indicates that the NIR properties of perylene bisimide derivatives are dependent on the nature of N-substituent and electronic environment of the molecule. This study shows that the existence of bonds with high-frequency fundamental vibrations and their counts which were introduced as affecting parameters on the NIR properties of the perylene pigments is not the main affecting factor and we should seek it elsewhere such as the crystal structure and intermolecular interactions of the pigments.     

Diametric swelling and hydrophilic characteristics of fibrous acrylic ion exchanger

In our previous works, modified acrylic fiber samples with highly ion‐exchange ability were described. These fibers contain suitable functional groups such as amidoxime, amid, and amine groups in their molecular chains. In this work, swelling in fiber diameter and hydrophilic properties of the modified acrylic fiber samples, as important parameters affecting on ion‐exchange efficiency, were investigated. The results showed that all modification treatments gave rise to diameter swelling ratio, but this does not mean that sample with highest swelling ratio in all cases can result in highest ability to ion‐exchange. In other words, the relation between them was complicated, and several factors such as the kind and the size of ion adsorbent and crosslinking ability of chemical reagent were used for modification interfere in ion‐exchange phenomena.The results of moisture adsorption indicate that incorporating functional groups by modification treatments enhance moisture adsorption in which samples with higher ion‐exchange ability possess higher hydrophilic property. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Europium (III) PVC membrane sensor based on N-pyridine-2-carboxamido-8-aminoquinoline as a sensing material

Conductometric study in acetonitrile solution shows the selectivity of PCQ toward europium ion. Therefore, a new europium PVC membrane electrode was prepared based on N-pyridine-2-carboxamido-8-aminoquinoline (PCQ) as an ion carrier. The electrode has a wide concentration range from 1.0 × 10^− 2 and 1.0 × 10^− 6 mol L^− 1, Nernstian slope of 19.8 ± 0.3 mV per decade and a detection limit of 6.4 × 10^− 7 mol L^− 1. The potentiometric response is pH independent in the range of 2.4-7.4. The proposed sensor has a relatively fast response time less than 10 s and it can be used for at least 2 months without any considerable divergence in its potentials. The proposed electrode revealed good selectivity toward europium ion in comparison with variety of other metal ions. The practical utility of the electrodes has been demonstrated by their use as indicator electrodes in the potentiometric titration of Eu^3 + ions with EDTA and for determination of Eu^3 + ion concentration in mixtures of two and three different ions.     

CSCNN: Cost-Sensitive Convolutional Neural Network for Encrypted Traffic Classification

Neural Processing Letters - By the rapid development of the Internet and online applications, traffic classification not only has changed to an interesting topic in the field of computer networks...     

CMS scheduling problem considering material handling and routing flexibility

Cell manufacturing as an application of group technology increases the flexibility and efficiency of the production. Cell scheduling problem, one of the subjects in cell manufacturing, has not been widely studied by researchers compared with other problems in cell manufacturing. In spite of great importance of material handling in cell scheduling, it has not been paid enough attention by researches. In this paper, a new mathematical model for cell scheduling problem considering material handling time and routing flexibility is proposed. The proposed model belongs to the mixed-integer nonlinear programs (MINLP). A linearization procedure is proposed to convert the MINLP to an integer program (IP) in order to develop more powerful optimization tools. Furthermore, a simulated annealing-based heuristic is developed to solve the large-size problems.     

Kinetics of murine decidual dendritic cells

Dendritic cells (DCs) are professional antigen presenting cells (APC) capable of induction of primary immune responses as well as immunologic tolerance. Myeloid and lymphoid subsets of murine DCs are able to shift cytokine responses of T cells toward Th2 and Th1 profiles respectively. Thus, DCs would be suitable candidates to mediate the balance of maternal immune responses to conception. We analyzed pregnancy-related variations in uterus and splenic DCs in a murine model. C57BL/6-mated Balb/c female mice with vaginal plugs were scarified at early, middle, and late pregnancy. Frozen sections of uterus and spleen at each stage of pregnancy were immunostained with CD11c- and MHC-II-specific antibodies. Two-color immunohistochemistry was also carried out using anti-CD11c and one of the antibodies against CD11b, CD8alpha, CD86, and DEC-205. Using morphometric analysis, the average density of DCs and relative percentage of myeloid (CD11c+, CD11b+) and lymphoid DCs (CD11c+, CD8a+) were determined at each stage. Our results showed that DCs are present throughout the pregnancy in decidua. The average density of decidual DCs at early pregnancy was significantly higher relative to middle and late gestation or to those of endometrial DCs of non-pregnant mice. Interestingly, the average density of decidual and splenic DCs, followed the same variations at different stages of pregnancy. The relative percentage of decidual lymphoid DCs (LDC) was significantly higher at mid-gestation when compared with other stages of pregnancy or non-pregnant mice. Inversely, the frequency of myeloid DCs (MDC) and the MDC/LDC ratio were statistically lower at the middle stage of pregnancy. A majority of decidual DCs expressed MHC-II and CD86. At early pregnancy, DCs were more concentrated subadjacent to the luminal epithelial layers, whereas at mid-or late gestation, DCs were randomly distributed in the stroma and around the epithelium. Mid-pregnancy period was a critical point with regard to splenic DCs kinetics, as both the average density of DCs and the frequency of MDCs decreased significantly when compared with early or late pregnancy, although the relative percentage of splenic LDCs did not change. Our data suggest that the balance of MDC and LDC is finely tuned throughout pregnancy, pointing an eminent immunoregulatory role of DCs in the maintenance of pregnancy.