Gheorghe AsachiTechnical University of Iasi

Iaşi, Romania

Gheorghe AsachiTechnical University of Iasi

Iaşi, Romania
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Iovan G.,Grigore T. Popa University of Medicine and Pharmacy | Stoleriu S.,Grigore T. Popa University of Medicine and Pharmacy | Solomon S.,Grigore T. Popa University of Medicine and Pharmacy | Ghiorghe A.,Grigore T. Popa University of Medicine and Pharmacy | And 2 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2017

The purpose of this study was to analyze the surface characteristics of the enamel adjacent to composite resin after finishing the restoration with different diamond and tungsten carbide burs. The topography of enamel was observed by using a scanning electron microscope. Finishing with extra-/ultra-fine carbide burs, and extra-fine diamond burs resulted in smooth surfaces. In few areas some superficial scratches with no clinical relevance were observed. Deep grooves were observed on the surface of enamel when fine diamond burs were used. Finishing of composite restorations with coarse burs should be avoided when there is a high risk of touching and scratching adjacent enamel during the procedure. © Published under licence by IOP Publishing Ltd.

Bulgariu L.,Technical University Gheorghe Asachi | Ceica A.,Gheorghe AsachiTechnical University of Iasi | Lazar L.,Gheorghe AsachiTechnical University of Iasi | Cretescu I.,Technical University Gheorghe Asachi | Balasanian I.,Gheorghe AsachiTechnical University of Iasi
Revista de Chimie | Year: 2010

In this study, removal of nitrate from aqueous solutions was investigated by anion exchange resin Purolite AlOO, using batch method. The experimental equilibrium data were modelled by Langmuir and Freundlich isotherms. The Langmuir equation describes sorption isotherm of nitrates with high correlation coefficients, and better than Freundlich model. According to the Langmuir model, at room temperature the maximum uptake capacity of resin for nitrates was obtained as 19.38 mglg at 334 K. The effect of temperature on the nitrates ion exchange process onto resin was also investigated, and various thermodynamic parameters, such as ΔG, ΔH, ΔS and Ea have been calculated. The experimental data were analyzed using two kinetics models: pseudo-fírst order and pseudo-second order. On the basis of these models the kinetics parameters (rate constants and equilibrium sorption capacities) were calculated.

Cailean D.,Technical University Gheorghe Asachi | Wukovits W.,Vienna University of Technology | Teodosiu C.,Technical University Gheorghe Asachi | Ungureanu F.,Gheorghe AsachiTechnical University of Iasi | Friedl A.,Vienna University of Technology
Clean Technologies and Environmental Policy | Year: 2014

The aim of this study is to analyze the performances of an integrated homogeneous Sono-Fenton-ultrafiltration process for the removal of 4-chlorophenol from wastewaters both from technical performance (expressed as phenolics concentration and chemical oxygen demand, COD, reduction) and energy consumption point of view, based on simulations using Aspen Plus® software. Based on experimental data (described in Cailean et al. 2014: "Integrated Sono-Fenton Ultrafiltration Process for 4-Chlorophenol Removal from Aqueous Effluents: Assessment of Operational Parameters (Part 1)") and statistical multi-regression models developed in MATLAB, a simulation model was implemented in Aspen Plus® and developed to calculate mass and energy balances. This model was used to assess the system behavior under various initial settings and process configurations. The effluent type, the presence of additional membrane units (ultrafiltration) and the variation of concentrate recirculation fractions were investigated. The results show that the integrated process registers over 90 % removal efficiency in the permeate of ultrafiltration and reduces between 70 and 90 % of the pollution load in the concentrate, expressed as phenolics concentration, depending on the scenarios analyzed. Recommendations concerning the use of recirculation options and suitable recirculation fractions of the concentrate are indicated, considering the quality of the resulting permeate and concentrate as well as the energy consumption. © 2014 Springer-Verlag Berlin Heidelberg.

Popescu M.-C.,Petru Poni Institute of Macromolecular Chemistry | Gomez R.,University of Alcalá | De La Mata F.J.,University of Alcalá | Rasines B.,University of Alcalá | And 2 more authors.
Journal of Nanoparticle Research | Year: 2013

Thermal analysis has a wide range of applications in pharmaceutical industry, in designing new molecules, control of raw materials, stability, compatibility studies, and development of new formulations. This paper evaluates the thermodynamic properties of two second generation G2 carbosilane dendrimers with peripheral ammonia groups by differential scanning calorimetry and TG/FTIR coupled techniques. The physical transformations have been detected and their thermodynamic characteristics have been estimated and analyzed. Both dendrimers are stable up to 150°C, have the Tg at 75 and 59°C and melting temperatures at 113 and 128°C, respectively. The decomposition process proved to be very complex and takes place in three steps in nitrogen atmosphere and four steps in air, for both types of dendrimers. IR spectroscopic analysis was used to observe the evolution of the gaseous products versus temperature. © 2013 Springer Science+Business Media Dordrecht.

Ioanid E.G.,Petru Poni Institute of Macromolecular Chemistry | Ioanid A.,Petru Poni Institute of Macromolecular Chemistry | Goras B.T.,Gheorghe AsachiTechnical University of Iasi | Goras L.,Gheorghe AsachiTechnical University of Iasi | Goras L.,Romanian Academy of Sciences
Measurement: Journal of the International Measurement Confederation | Year: 2013

The assessment of cultural heritage objects cleaning by HF cold plasma treatment is hard to quantify. One method is based on direct comparison of photographic images acquired before and after treatment, a subjective evaluation, depending on the rigor and visual accuracy of the observer. An objective assessment is based on the analysis of statistical parameters of color histogram (mean, standard deviation, skewness), obtained by processing the photographic images taken before and after the cleaning. The paper aims to use the data of SEM-EDX analysis concerning the HF cold plasma cleaning of some objects in the statistical processing of their photographic images, extending the application domain and contributing to the understanding of statistical parameters significance (mean, standard deviation, skewness and kurtosis) in practice. The information concerning the changes induced by plasma active species on the object (coin) surface, revealed by statistical analysis, have been supplemented by SEM-EDX analyses, confirming the removal of contaminants from the coin surface. © 2013 Elsevier Ltd. All rights reserved.

Racu C.,Gheorghe AsachiTechnical University of Iasi | Diaconescu R.,Gheorghe AsachiTechnical University of Iasi | Grigoriu A.-M.,Gheorghe AsachiTechnical University of Iasi | Grigoriu A.,Gheorghe AsachiTechnical University of Iasi
Cellulose Chemistry and Technology | Year: 2010

The present paper studies the way the reactive derivative monochlorotriazinyl-ß-cyclodextrin can be grafted on bast fibres simultaneously with their wet spinning. Process modelling involved simultaneous mechanical and chemical processing, at different parameters of wet spinning-grafting (concentration of monochlorotriazinyl-ß-cyclodextrin and speed of the material in the impregnation stage). The mathematical methods of dispersion analysis and regression were applied to obtain optimum values of the process parameters. To attain physico-mechanical characteristics adequate for a 100% hemp yarn and an optimum grafting degree for subsequent inclusion operations, a soaking time of 23.7 sec and a solution concentration of 55 g/L monochlorotriazinyl-ß-cyclodextrin are required for simultaneous wet spinning-grafting.

Ignat I.,Gheorghe AsachiTechnical University of Iasi | Stingu A.,Gheorghe AsachiTechnical University of Iasi | Volf I.,Gheorghe AsachiTechnical University of Iasi | Popa V.I.,Gheorghe AsachiTechnical University of Iasi
Cellulose Chemistry and Technology | Year: 2011

Grapes (Vitis vinifera L.) belong to world's largest fruit crops. Since about 80% of the total amount is used in wine-making, the rest of 20% (about 10 million tons) of grape pomace arises within a few weeks from the harvest campaign. The seeds constitute a considerable ratio of the pomace, amounting to 38-52% on a dry matter basis. The results of certain studies have indicated that the polyphenols present in grape seeds in significant concentrations could be classified into two groups: flavonoids and non-flavonoids. The present study employed high-performance liquid chromatography (HPLC) to analyze the phenolic compounds in the seed extract. Spectrophotometric methods were employed for the determination of total phenolic content, total tannins, flavonoids, flavanols and antocyanins. The aqueous polyphenols extract obtained from grape seeds was analyzed in germination tests, to evaluate the response of three different plants (oat, rape and maize) in terms of growth and development. Biometrie measurements and quantitative determination of green biomass showed that grape seed extract amendments stimulated root elongation for oat and maize, as well as green biomass accumulation.

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