Kinetics of Adhesion Staphylococcus aureus on Glass in the Presence of Sodium Lauryl Sulfate

Bacterial contamination of surfaces is a natural and spontaneous process that often results in the formation of biofilms. The extracellular matrix of biofilm is mostly composed of proteins, polysaccharides, and extracellular DNA and is responsible for the strong persistent ability of biofilm in the food industry. Despite cleaning and disinfection processes, persistent bacteria cause a major problem in food processing environments. Synthetic surfactants, mainly anionic surface-active agent, are commonly used as detergents, foaming agents, wetting agents, emulsifiers, and dispersants. Their tendency to adsorb to surfaces and interfaces and modify their surface tension, is considered among their main properties. They also have the ability to attach to bioactive macromolecules such as proteins, peptides, and DNA causing cell membrane damage. In order to estimate the adhesion kinetic and proliferation of pathogenic bacteria Staphylococcus aureus, the surface of glass was coated with anionic surfactant Sodium Lauryl Sulfate (SLS). Moreover, SLS was added in suspension with the culture medium. The physicochemical properties of the material were calculated using the contact angle measurement method and bacterial hydrophobicity using the microbial adhesion to hydrocarbons (MATH) test. The obtained results showed that the number of adhering cells increased gradually as a function of time. However, changing the surface properties of the glass and S. aureus has affected the rate of adherent cells with time as well as their organization. SLS inhibited the attachment of cells, whether it is added with the microbial suspension or at the surface of the support. Generally, the present article points to a relationship between the microbial adhesion, the surface chemistry of the solid material and the bacteria, and the suspension properties.     

In quest of new document relations: evaluating co-opinion relations between co-citations and its impact on Information retrieval effectiveness

Document relational network has been effective in retrieving and evaluating papers. Despite their effectiveness, relational measures, including co-citation, are far from ideal and need improvements. The assumption underlying the co-citation relation is the content relevance and opinion relatedness of cited and citing papers. This may imply existence of some kind of co-opinionatedness between co-cited papers which may be effective in improving the measure. Therefore, the present study tries to test the existence of this phenomenon and its role in improving information retrieval. To do so, based on CITREC, a medical test collection was developed consisting of 30 queries (seed documents) and 4823 of their co-cited papers. Using NLP techniques, the co-citances of the queries and their co-cited papers were analyzed and their similarities were computed by 4 g similarity measure. Opinion scores were extracted from co-citances using SentiWordnet. Also, nDCG values were calculated and then compared in terms of the citation proximity index (CPI) and co-citedness measures before and after being normalized by the co-opinionatedness measure. The reliability of the test collection was measured by generalizability theory. The findings suggested that a majority of the co-citations exhibited a high level of co-opinionatedness in that they were mostly similar either in their opinion strengths or in their polarities. Although anti-polar co-citations were not trivial in their number, a significantly higher number of the co-citations were co-polar, with a majority being positive. The evaluation of the normalization of the CPI and co-citedness by the co-opinionatedness indicated a generally significant improvement in retrieval effectiveness. While anti-polar similarity reduced the effectiveness of the measure, the co-polar similarity proved to be effective in improving the co-citedness. Consequently, the co-opinionatedness can be presented as a new document relation and used as a normalization factor to improve retrieval performance and research evaluation.

     

High speed residue number system comparison for the moduli set {2^n-1, 2^n, 2^n＋}

The Residue Number System （RNS） exploits advantages of fast computing, parallelism and fault tolerant because of its carry-free property in operations. This essential property gives RNS this ability to eliminate the problem of carry propagations in calculations and provides high-speed computing consequently. In RNS some operations like addition and multiplication can be done in parallel, faster and with less complexity than conventional numeric systems so it is used in many applications like Digital Signal Processing （DSP）, Cryptography and Image Processing. Normally these applications require comparison in their operations. Comparison is a fundamental operation in numeric systems. On the other hand, the noticed property makes comparison difficult and complex in RNS. The pervious methods or algorithms for RNS comparison used redundant moduli set, ROM look-up tables or implemented complete RNS to binary（R/B） convert. We propose a new RNS comparison technique, which performs RNS comparison without using a redundant module and complete converting from RNS to binary system. Our technique implements RNS comparison much faster applying a few more hardware than previous techniques.     

Molecular modeling of the gaseous penetrants permeabilities through 4A,DDR and silicalite-1 zeolites incorporated in mixed matrix membranes

A theoretical model is used to predict O₂, N₂, CO₂, CH₄, N₂O, and Ar gaseous penetrants’ permeabilities through zeolitic filler particles of 4A, DDR and silicalite-1 using their adsorption and diffusion data with minimum and maximum absolute relative errors (AREs) as 4.3 and 6.9% for N₂ and CH₄ permeabilities through 4A zeolite, respectively. Average AREs for 4A zeolites incorporated in mixed matrix membranes (MMMs) were found for O₂ permeability using modified Felske’s and Maxwell’s models as 1.2 and 55.6%, respectively. Those for DDR/MMMs and silicalite-1/MMMs CO₂ permeabilities were found as 0.7 and 1.8% for Bruggeman’s and Maxwell’s models and 3.1 and 22.3% for Maxwell’s and Lewis-Nielsen’s models, respectively.     

Rectangular shaped zinc oxide nanoparticles: Green synthesis by Stevia and its biomedical efficiency

Synthesis and properties of a new zinc oxide nanostructure, and its antimicrobial applications are presented. The synthesis method was fast, clean and green using a natural sweetener (Stevia) extract. The synthesized nanoparticles had a rectangular shape with a size range of 10–90?nm. The antimicrobial activity of the biosynthesized nanoparticles in parasitic strain of Leishmaniasis major and bacterial strains of Staphylococcus aureus and Escherichia coli was studied. It was found that low concentrations of the nanoparticles are required for complete prevention of growth of these organisms in vitro.     

Taguchi orthogonal array design for the optimization of hydrogel nanoparticles for the intravenous delivery of small‐molecule drugs

In this study, a 16 runs Taguchi method was applied as an experimental design to establish the optimum conditions for hydrogel nanoparticle preparation. Five relevant factors, chitosan (CS) concentration, pentasodium tripolyphosphate (TPP) concentration, CS‐to‐TPP volume ratio, addition time of the TPP solution to the CS solution, and temperature, were selected as the main determinants, and the effects of each factor on the size of the hydrogel nanoparticles were studied at four levels. The statistical analysis revealed that the most important factors contributing to the achievement of minimum particle size were the CS‐to‐TPP volume ratio and the CS concentration. By solving a set of equations derived from the differentiation of the final model, we established the optimum conditions for hydrogel nanoparticle preparation as follows: CS concentration = 0.28% w/v, TPP concentration = 3.17% w/v, TPP/CS = 1 : 8, temperature = 25.66°C, and addition time of the TPP solution to the CS solution = 0.4 min. Also, an analysis of response at the different levels of the factors indicated that there was no remarkable interaction between them. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Average consensus in networks of dynamic multi-agents with switching topology: infinite matrix products

This paper deals with the average consensus problem in a multi-agent system with switching interaction topology modeled as a weighted digraph. The convergence analysis is performed in both discrete-time and continuous-time dynamics based on the theory of infinite matrix products. Conditions for system convergence to average consensus are derived in the form of constraints on direct and reverse graphs and the structure of adjacency elements among the agents. Furthermore, a sufficient condition is provided for convergence to average consensus in systems in which the interaction topology is balanced over infinite contiguous non-overlapping time intervals instead of being balanced continuously. Numerical simulations are given to demonstrate the effectiveness of the theoretical results.     

Synthesis and properties of novel biodegradable poly(ε‐caprolactone)/ poly(ethylene glycol)‐based polyurethane elastomers

Elastomeric polyurethanes with tunable biodegradation properties and suitable for numerous biomedical applications were synthesized via reaction of epoxy‐terminated polyurethanes (EUPs) with 1,6‐hexamethylenediamine as curing agent. The EUPs themselves were prepared from glycidol and isocyanate‐terminated polyurethanes made from poly(ε‐caprolactone) (PCL) or poly(ethylene glycol) (PEG) and 1,6‐hexamethylene diisocyanate. All the polymers were characterized by conventional methods, and their physical, mechanical, thermal, and degradation properties were studied. The results showed that the degradation rate and mechanical properties of the final products can be controlled by the amount of PEG or PCL present in the EUP. Increasing the PEG content causes an increase of hydrolytic degradation rate, and increasing the PCL content improves the mechanical properties of the final products. Evaluation of cytotoxcicity showed nontoxic behavior of the prepared samples, but the cytocompatibility of these polymers needs to be improved. Copyright © 2006 Society of Chemical Industry     

Barium carbonate nanostructures: Biosynthesis and their biomedical applications

In recent years, nanostructures and nanoarchitectures have attracted much attention in the development of biomedicine and nanomedicine. The plant-mediated synthesis of barium carbonate nanoparticles (BACN) has been performed using barium chloride and aqueous extract of natural sweetener (Stevia). In this study, the biosynthesis of BACN has been selected due to the useful medicinal potentials and suitable obtained biocompatibility of produced nanoparticles as well as its simplicity, lesser production steps, and cost-effectiveness. Barium carbonate nanostructures were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscope. The toxicity of BACN on U87 brain cancer cells was evaluated based on MTT assay. According to the results, the prepared nanostructures can be employed for biomedical applications, especially cancer therapy.