Aurelia Cristina Nechifor

Poly(methyl methacrylate) with TiO2 nanoparticles inclusion for stereolitographic complete denture manufacturing − the fututre in dental care for elderly edentulous patients?

OBJECTIVES The aim of this study was to obtain a Poly(methylmethacrylate) (PMMA)-TiO2 nanocomposite material with improved antibacterial characteristics, suitable for manufacturing 3D printed dental prosthesis. METHODS 0.2, 0.4, 0.6, 1, 2.5 by weight% of TiO2 nanoparticles have been added to the commercially available stereolithographic PMMA material and the obtained nanocomposites have been analyzed using FTIR, SEM and also tested for antimicrobial efficacy against bacterial cultures from Candida species (C. scotti). RESULTS SEM images and EDX results highlighted the presence of TiO2 in PMMA nanocomposites. The elemental composition (EDX) also showed the presence of other fillers included in stereolithographic PMMA solution. FTIR analysis clearly revealed changes in polymeric matrix structure when adding TiO2 nanoparticles. Sample containing 0.4, 1 and 2.5wt% TiO2 nanoparticles inhibited the growth of Candida scotti strain in standard conditions according to the toxicity control method (DHA). Increasing quantity of nano-titania has resulted in particles fooling, forming new aggregates instead of the homogenous dispersion of nanoparticles with modified viscosity characteristics and expected lower mechanical parameters. CONCLUSIONS Significant improvements in polymer characteristics and nice dispersion of the TiO2 nanoparticles have been noticed for 0.4wt%, therefore it was used for stereolitographic complete denture prototyping. CLINICAL SIGNIFICANCE Incorporation of TiO2 nanoparticles in PMMA polymer matrix was proved to have antibacterial effects, specifically on Candida species. The newly obtained 0.4% nanocomposite was successfully used with stereolitographic technique for complete denture manufacturing. However, mechanical and biocompatibility tests need to be performed in order to extend the clinical usage.

Polysulfone-functionalized multiwalled carbon nanotubes composite membranes for potential sensing applications

In order to combine the advantages of functionalized multiwalled carbon nanotubes as a highly electronic conductive chemical species to that of polysulfone as a membrane material this paper reports the results concerning the synthesis of new polymeric-carbon nanotubes composite membranes based on polysulfone with functionalized double wall (DWNT) amino carbon nanotubes with sulfated cyclodextrine, are shown, with potential applications in gas sensing. The above synthesized membranes were structurally characterized using Scanning Electron Microscopy, Atomic Force Microscopy, FT-IR spectroscopy, thermal analysis.

Polysulfone- doped polyaniline composite membranes. synthesis and electrochemical characteristics

In order to combine the advantages of polysulfone (PSf) as a membrane material to that of polyaniline as a conductive polymer, one has attempted to obtain novel polysulfone-polyaniline composite membranes by a newly improved technique comparing to the existing ones. The strong point of this technique consists in a phase inversion by immersion precipitation accompanying by chemical reaction followed by the activation of polyaniline with sulfonated beta-cyclodextrine. The above synthesized membranes were structurally characterized using Scanning Electron Microscopy, FT-IR spectroscopy, thermal analysis. The ionic conductivity and electrochemical characteristics were also determined by Electrochemical Impedance Spectroscopy.

Different spectrophotometric methods for antioxidant activity assay of four Romanian herbs

The present study investigates the antioxidant activities of some Romanian plants, using different spectrophotometric methods (FRAP I, FRAP II, and CUPRAC). The plants investigated are hawthorn (Crataegus oxyacantha), bilberry (Vaccinium myrtillus L.), rosehip (Rosa canina), and chokeberries (Aronia melanocarpa). Hawthorn is used to treat a wide variety of inflammatory conditions, but the primary use is generally restricted for treating hypertension, ischemic heart disease, congestive heart failure, and arrhythmia. Investigations have proved the safe and reliable use of plant and plant extracts for treatment of cardiovascular disorders.

Aqueous Phase Biosorption of Pb(II), Cu(II), and Cd(II) onto Cabbage Leaves Powder

Abstract In this study, the biosorption of lead (Pb(II)), copper (Cu(II)), and cadmium (Cd(II)) ions from aqueous solution using waste of cabbage leaves powder (CLP) was investigated as a function of pH, shaking time, initial metal concentration, and biosorbent dose. The maximum removal efficiency at optimum condition in single biosorption system was 95.67, 92.42, and 88.92 % for Pb(II), Cu(II), and Cd(II) ions, respectively. These values reduced in ternary systems in the same sequence. Langmuir and extended Langmuir isotherm models were found to be the best fit of the isotherm data for single and ternary biosorption systems, respectively. The kinetic data of the three metals were better fit by the pseudo-second-order model with higher coefficient of determination and more closely predicted uptake. In addition, the results showed that the intraparticle diffusion was the dominating mechanism. Thermodynamic study showed that the biosorption of Pb(II), Cu(II), and Cd(II) onto CLP was a chemical reaction which was exothermic in nature. Finally, SEM image shows that CLP has a number of heterogeneous small pores while the Fourier transform infrared (FTIR) spectroscopic analysis showed that the carboxyl, amine, and hydroxyl groups are the major groups that are responsible for the biosorption process.

In Situ Generation of Polyaniline inside Zeolite Pores for Retention of Ions and for Controlled Drug Delivery

In order to improve the capabilities of zeolites for biomedical applications, new composite materials based on polyaniline in-situ generated inside zeolite pores were developed. As precursors for polyaniline several monomers (like aniline and p-phnylenediamine) were used and different oxidant systems (like ammonium peroxodisulphate/HCl, sodium vanadate/ethylic alcohol) were studied and were used for the separation of different biological interest ions and release of antibiotics.

New sensor based on membranes with magnetic nano-inclusions for early diagnosis in periodontal disease

A series of sodium selective membranes with magnetic nano-inclusions using p-tertbutyl calix[4]arene as ionophore and polymeric matrix (polyvinyl chloride) have been developed, and the corresponding sodium selective sensors were obtained for the first time. A linear range was registered between 3.1 × 10-5 and 10-1moldm-3 and near Nernstian electrochemical answer: 55.73mV/decade has been recoreded for PVC (polyvinyl chloride) - based sodium selective sensor, with a response time of 45s. Due to their small dimensions, sensors could be used for measuring ions from the gingival crevicular fluid directly into the peri-odontal pocket, avoiding the difficulties of collecting an appropriate amount of fluid for analysis. Alterations in the inorganic ions level could be evidenced with this new device, assisting the early diagnosis and prevention of periodontal disease.

Fabrication, characterization, and modelling of polysulfone composite membranes with enhanced adsorbent capabilities

ABSTRACT The aim of the study is to fabricate and evaluate the efficiency of polysulfone (Psf) composite membranes as material used for transport and adsorption. Morphological and chemical investigations were used along with collateral methods based on optimization mathematical algorithms application. The membranes have been prepared by Psf’s coagulation method through phase inversion, and the systematic investigations revealed a multilayer configuration of superficial macro-pores and in-depth-nano-pores. The transport and adsorption of biologically active substances through composite membranes were illustrated by mathematical models elaborated in MathCAD, in order to describe the connection between the adsorption membranes’ capacity, initial concentration of bioactive substance, and contact time.

Simulation of membrane processes with applications in transport and adsorption of nitrate ions

This paper represents the answer to many challenges in terms of numerical models for the transport of pollutants in drinking water. Due to these reasons this paper represents a particular methodology for estimating the velocity and dispersion coefficients. The aqueous solution transport and adsorption was performed using the COMSOL mathematical program.

Membrane Separation and Concentration Study of Biological Active Compounds

Abstract This study highlights the use of composite membranes at the expense of commercial membranes used for separation and concentration of biologically active compounds of different medicinal plants used in phytotherapy. The hydroalcoholic extracts of hawthorn (Crataegus oxyacantha), chokeberry (Aronia melanocarpa), rosehip (Rosa canina) and bilberry (Vaccinium myrtillus L) by membrane processes were used in this study. Biologically activity subtances obtained from membrane separation and concentration were analyzed by UV-Vis spectroscopy and infrared spectroscopy (FT-IR), to highlight their main properties. UV-Vis spectroscopy also analyzed sugars and tannins. Sugars are found in all plants herbal medicinal interest. The results of this study will be used to obtain a food supplement adjuvant in cardiovascular disease.