ATR-FTIR and NMR spectroscopic studies on the structure of polymeric gel electrolytes for biomedical applications

The structure of polymeric gel membranes to be used as electrolytes in the recording of bioelectrical signals has been investigated by means of ATR-FTIR and ⁷Li and ¹³C MAS NMR spectroscopies. The membranes, based on PMMA, 1,2-diethoxyethane and lithium perchlorate, showed different ionic conductivity as a function of their composition. Such differences have been analyzed on the basis of spectroscopic data and the existence of interactions with the ester function in the polymeric matrix was determined. Spectroscopic data allowed to establish the optimal lithium concentration needed to achieve best ionic conductivity.     

Endosomal Escape of Polymer‐Coated Silica Nanoparticles in Endothelial Cells

Current investigations into hazardous nanoparticles (i.e., nanotoxicology) aim to understand the working mechanisms that drive toxicity. This understanding has been used to predict the biological impact of the nanocarriers as a function of their synthesis, material composition, and physicochemical characteristics. It is particularly critical to characterize the events that immediately follow cell stress resulting from nanoparticle internalization. While reactive oxygen species and activation of autophagy are universally recognized as mechanisms of nanotoxicity, the progression of these phenomena during cell recovery has yet to be comprehensively evaluated. Herein, primary human endothelial cells are exposed to controlled concentrations of polymer‐functionalized silica nanoparticles to induce lysosomal damage and achieve cytosolic delivery. In this model, the recovery of cell functions lost following endosomal escape is primarily represented by changes in cell distribution and the subsequent partitioning of particles into dividing cells. Furthermore, multilamellar bodies are found to accumulate around the particles, demonstrating progressive endosomal escape. This work provides a set of biological parameters that can be used to assess cell stress related to nanoparticle exposure and the subsequent recovery of cell processes as a function of endosomal escape.     

Internal mass transfer coefficient within single bubbles. Theory and experiment

Mass transfer coefficients inside single rising bubbles are measured in the system SO₂, N₂—H₂O by using a photographic technique. The differential equations which govern the phenomena, including internal toroidal circulation inside the bubble, are also presented. Assumptions are incompressible, steady, irrotational outside flow and inviscid, steady, axisymrnetric inside flow. From the mass transport viewpoint, restrictions are: binary dilute mixture and axial symmetry. The theoretical solution is presented as Sh vs. Pe and a comparison with experiments shows good agreement. Theoretical predictions for a stagnant fluid inside the bubble were also compared with the experimental results.     

A pilot study of constructed wetlands using duckweed (Lemna gibba L.) for treatment of domestic primary effluent in Israel

Constructed wetlands are well known as highly efficient system to treat wastewater from different sources. This treatment system is cost-effective for reuse in desert areas. A continuous flow, free water surface (FWS) pilot wetland using the duckweed plant Lemna gibba L. was constructed at the Blaustein Institute for Desert Research in Kiryat Sde Boker of the Negev, Israel, and operated on domestic primary effluents. Water quality and system efficiency were observed during the experiment for reuse purposes. Results indicated that, hydraulic residence time averaged 4.26+/-0.61d, average influent flow rate was 0.234+/-0.027m(3)/d and hydraulic load 0.22+/-0.03m/d. Hydraulic efficiency in the system was high and allowed good settling conditions. Suspended solids and organic matter removals were the highest and effluent concentrations were 13.1+/-9.7 and 40.3+/-11.9mg/l for TSS and total BOD(5), respectively. Nitrogen removal was lower (10-20%) but slightly increased with higher nitrogen loads. Therefore, nitrogen content in the plants was high (4.3+/-0.5%/kg dry plant). Phosphorus removal was negligible. High removal for fecal coliform (approximately 95%) and effluent turbidity (> 50%) were also observed.     

Determination of simple sugars,malic acid and total phenolic compounds in apple pomace by infrared spectroscopy and PLSR

The aim of this work was to develop a fast, versatile, inexpensive and environmentally safe analytical method to quantify simple sugars, malic acid and total phenolic compounds in apple pomace, considering its potential use as a raw material with value instead of as an industrial waste. Diffuse reflectance infrared spectroscopy (DRIFTS) measurements of twenty‐six samples of apple pomace were analysed by partial least squares regression (PLSR), using several signal pre‐processing methods. Multivariate models developed with four to five latent variables (LVs) and based in the MIR (mid‐infrared) region had good prediction for the determination of sucrose, fructose, malic acid and total phenolic compounds, with average errors between 3.9% and 6.6%. By contrast, glucose was better determined by models developed in the NIR (near‐infrared) region and using six LVs, yielding an average error lower than 7.4%. These results confirmed the feasibility of the multivariate spectroscopic approach as an alternative for expensive and time‐consuming conventional chemical methods.     

Side-effect free functions in object-oriented languages

This paper presents a method for statically verifying that functions do not produce side-effects, in an object-oriented language. The described model, although not allowing any changes to pre-existing objects during a function call, permits an imperative style of programming, where new objects can be freely created and manipulated.     

Efficacy of waterborne polyurethane to prevent the enzymatic attack on paper‐based materials

The chemical and biological deterioration of paper‐based materials is mainly due to the degradation of its main component, the cellulose. However, paper also contains small amounts of organic and inorganic additives which might influence its biodegradability. To protect the paper‐based materials against various degradative agents, coating treatments with polymeric materials might be developed. In this study, the protective effect of commercial waterborne polyurethanes (WPU) against an enzymatic attack was investigated. Uncoated and coated samples with WPU of newsprint were subjected to degradation by enzymatic complexes (cellulosomes) produced by Clostridium cellulolyticum for different incubation times and then characterized using several analytical techniques (energy dispersive X‐ray fluorescence, scanning electron microscopy, nuclear magnetic resonance, Raman and infrared spectroscopy) with the aim to assess if waterborne polyurethanes can be used in paper conservation, looking at their efficacy against the biodegradation induced by enzymes. The selected waterborne polyurethanes showed a high effectiveness in the protection of paper‐based materials when they were submitted to the enzymatic attack. Indeed, their presence delayed the destruction of the cellulose matrix and the release of both soluble sugars and paper additives. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009