Chemomechanical Systems: Study of Contraction and Mechanical Work of Poly(Acrylonitrile) Gel Fibers

Poly(acrylonim1e) fibers were preoxidated under stress, in the presence of air, then saponified by boiling in alkaline solutions. The chemomechani-cal behavior of these fibers, expressed as contraction and mechanical work, under different loads and in different solvent-nonsolvent and/or base-acid systems were investigated. Total nitrogen content, carboxyl groups content, tensile strength, and cross-link density were determined. Both contraction and mechanical work were expressed as functions of applied load in every studied system. The results of chemomechanical measurements were connected to those of chemical and physical investigations. Significant differences in chemomechanical behavior were found to be the result of different stress conditions during the preoxidation stage.     

Robocast zirconia-toughened alumina scaffolds: Processing,structural characterisation and interaction with human primary osteoblasts

Zirconia-toughened alumina (ZTA) is the gold-standard ceramic in hip arthroplasty, but still lacks direct osseointegration and a metal shell, often coated with a bioactive layer, is currently required. The latter could potentially be replaced by a thinner, architectured ZTA layer, thereby allowing for larger acetabular components, with larger range of motion and lower dislocation risk. Robocasting may be an adequate technique to fabricate the architectured layer. Therefore, as a first step, this study aimed to produce ZTA scaffolds (3D-ZTA) by robocasting and assess their in vitro response. Shape retention was achieved by using a stable, well-dispersed, high solid loading ink injected in acid pH waterbath. 3D-ZTA exhibit regularly spaced microporous, rough struts and fully interconnected macroporosity. Human primary osteoblasts were homogenously distributed inside 3D-ZTA and showed increased osteogenic marker expression compared to 2D-ZTA control. Further work will focus on optimizing scaffold design to improve cell retention and extracellular matrix maturation.     

Novel (Phenothiazinyl)Vinyl-Pyridinium Dyes and Their Potential Applications as Cellular Staining Agents

We report here the synthesis and structural characterization of novel cationic (phenothiazinyl)vinyl-pyridinium (PVP) dyes, together with optical (absorption/emission) properties and their potential applicability as fluorescent labels. Convective heating, ultrasound irradiation and mechanochemical synthesis were considered as alternative synthetic methodologies proficient for overcoming drawbacks such as long reaction time, nonsatisfactory yields or solvent requirements in the synthesis of novel dye (E)-1-(3-chloropropyl)-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium bromide 3d and its N-alkyl-2-methylpyridinium precursor 1c. The trans geometry of the newly synthesized (E)-4-(2-(7-bromo-10-ethyl-10H-phenothiazin-3-yl)vinyl)-1-methylpyridin-1-ium iodide 3b and (E)-1-methyl-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium tetrafluoroborate 3a′ was confirmed by single crystal X-ray diffraction. A negative solvatochromism of the dyes in polar solvents was highlighted by UV-Vis spectroscopy and explanatory insights were supported by molecular modeling which suggested a better stabilization of the lowest unoccupied molecular orbitals (LUMO). The photostability of the dye 3b was investigated by irradiation at 365 nm in different solvents, while the steady-state and time-resolved fluorescence properties of dye 3b and 3a′ in solid state were evaluated under one-photon excitation at 485 nm. The in vitro cytotoxicity of the new PVP dyes on B16-F10 melanoma cells was evaluated by WST-1 assay, while their intracellular localization was assessed by epi-fluorescence conventional microscopy imaging as well as one- and two-photon excited confocal fluorescence lifetime imaging microscopy (FLIM). PVP dyes displayed low cytotoxicity, good internalization inside melanoma cells and intense fluorescence emission inside the B16-F10 murine melanoma cells, making them suitable staining agents for imaging applications.     

The Optimization of the Production of Methyl Esters from Corn Oil Using Barium Hydroxide as a Heterogeneous Catalyst

In recent years, vegetable oils, as renewable raw materials, became a promising feedstock for chemicals and biodiesel production. The main products derived from oils are esters of fatty acids, especially methyl esters, obtained by their transesterification with methanol, in presence of acid or alkaline catalysts. The use of such catalysts implies the need for washing operations, which leads to environmental pollution. In the present paper, the response surface methodology based on a central composite design, has been developed to optimize the process of transesterification of corn oil. Ba(OH)₂ in presence of diethyl ether was used as catalyst. A quadratic polynomial equation was obtained. It correlates the reaction parameters [methanol/oil molar ratio (x _r), reaction time (x _t) and catalyst concentration (x _c)] with methyl esters yield. Analysis of variance analysis showed that only methanol/oil molar ratio and catalyst concentration have had the most significant influences on the conversion. The maximum methyl esters yield was obtained using the following optimum parameters: methanol/corn oil ratio of 11.32, reaction time of 118 min and catalyst concentration of 3.6 wt%.     

Altering the emission properties of conjugated polymers

Many technological applications that have had tremendous impact on our society and lifestyle are exploiting the emission properties of organic species such as conjugated polymers and organic small‐molecule semiconductors. The most prominent case‐in‐point here are possibly organic light‐emitting diodes, which have found use in information displays, touch screens and beyond. To further advance the rapid development of these powerful and versatile technologies, it will be of paramount importance to gain fundamental insights about which strategies and processes we can employ to alter, control and eventually enhance the emission properties of this interesting class of material. In this work, we focus on macromolecular systems and review the most important categories of tools that can be employed to efficiently alter their emission properties by manipulating their molecular architecture and electronic structure; by influencing their molecular ordering, packing motifs and overall microstructure; as well as by utilizing the ability of some of these materials to respond to external stimuli and other physical parameters (pressure, light exposure etc.) and/or to interact with other compounds, including systems of different functionalities. © 2015 Society of Chemical Industry     

Adsorption studies on copper,cadmium, and zinc ion removal from aqueous solution using magnetite/carbon nanocomposites

Magnetite/carbon nanocomposites were tested as adsorbents for removal of metal ions from aqueous solutions. The effect of adsorption parameters such as solutions pH (ranging between 2 and 9), the nature and the quantity of the sorbent (10, 20, 40, and 60 mg), initial concentration of metal ions (10, 30, 50, 100, and 150 mg/L), and temperature (25, 45, and 65°C) was evaluated. The removal efficiency of metal ions depends on solution pH and increases with increasing carbon content, the dose of magnetite/carbon nanocomposites, and the temperature and decrease with initial concentration of the metal ions. The adsorption kinetics was described by pseudo-second-order model, and the equilibrium experimental data were well fitted to the Sips isotherm, yielding a maximum adsorption capacity of 41.11, 76.67, and 48.45 mg/g for copper, cadmium, and zinc, respectively. The thermodynamic parameter Gibbs free energy was determined to be negative, which indicated that the adsorption process is spontaneous. The optimum conditions (1 g/L adsorbent, 25°C, and pH 6) were selected for removal of metal ions from real wastewaters, with good results indicating that investigated nanocomposites could be used for the application in real systems.     

Dynamic modeling of the secondary drying stage of freeze drying reveals distinct desorption kinetics for bound water

In freeze drying, the desorption step for reaching a low target moisture content may take a significant fraction of the total process duration. Because the long-term stability of freeze-dried biological products strongly depends on the current moisture content, modeling the desorption process may help safely optimize the secondary drying step. Most published models assume a first-order desorption kinetic, but experimental evidence shows that strongly bound water in the monolayer takes a much longer time to be desorbed than less bound water in multilayer. The proposed model for desorption of freeze-dried lactic acid bacteria preparation accounts for monolayer and multilayer water state in the solid matrix, with very different desorption kinetics. Results showed that the ratio of characteristic desorption times (monolayer/multilayer) was almost 30. Temperature dependence was adequately described by an Arrhenius law in the range of 15 to 40°C. Model parameter identification used simultaneously gravimetric measurements with high time resolution and direct Karl-Fisher titration, from several experiments at different, time-varying temperatures.     

Using contexts and R-R interval estimation in lossless ECG compression

The paper presents a new lossless ECG compression scheme. The short-term predictor and the coder use conditioning on a small number of contexts. The long-term prediction is based on an algorithm for R-R interval estimation. Several QRS detection algorithms are investigated to select a low complexity and reliable detection algorithm. The coding of prediction residuals uses primarily the Golomb-Rice (GR) codes, but, to improve the coding results, escape codes GR-ESC are used in some contexts for a limited number of samples. Experimental results indicate the good overall performance of the lossless ECG compression algorithms (reducing the storage needs from 12 to about 3-4 bits per sample). The scheme consistently outperforms other waveform or general purpose coding algorithms.     

Enabling customers engagement and collaboration for small and medium-sized enterprises in ubiquitous multi-channel ecosystems

Over the last few years, we have encountered an exponential growth in online communication opportunities. Organizations have more and more ways to connect and engage with their current or future customers. The existence of more opportunities in connecting to people can be both an enabler and a burden. Being present at a multitude of different channels requires the effective management of a very large number of adapted contents, formats, and interaction patterns fulfilling the communication and cooperation needs of distributed target groups. In this respect, we integrate existing fragmented communication and monitoring approaches into a full-fledged communication model as a basis for an adequate engagement approach. We describe applications of our approach in both the eTourism and manufacturing domain. In this paper, we introduce an approach that will enable communication, collaboration and value exchange of users through a multitude of online interaction possibilities based on the use of semantic technology. Finally, we also compare our approach with existing solutions with respect to the identified challenges in this subject.