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Manea L.R.,Technical University Gheorghe Asachi | Sandu I.,Romanian Inventors Forum | Sandu I.,Al. I. Cuza University
Revista de Chimie | Year: 2015

Electrospinning came into prominence during the last years as a promising procedure to obtain fibers sized under 1μm from a wide variety of polymers. The electrospinning process, technology and equipment are relatively complex, yet efficient, able to produce continuous, exceptionally long fibers, with controlled orientation. Nowadays, the electrospinning technology is the only one able to lead to the formation of continuous filaments, with diameters of some nanometers. The present paper contains a study related to the processability of polyetherimide solution with a concentration of 12%, using as solvents a mixture of dimethylacetamide/tetrahydrofuran 1:1 ratio. Adjusting the flow rate, the distance between needles and collector and the voltage, 100 technological experiments were carried out. The main destination of these nanofibers is filteringsurfaces. All fibers were studied by Scanning Electron Microscope method for analyzing the consistency of fibers disposal, the fibers diameter uniformity, and the presence of defects on fibers.

Manea L.R.,Technical University Gheorghe Asachi | Nechita E.,Vasile Alecsandri University of Bacu | Sandu I.,Romanian Inventors Forum | Sandu I.,Al. I. Cuza University
Revista de Chimie | Year: 2015

The transversal dimension of electrospun fibers depends on a multitude of technological, constructive and environment factors and not finally, on the characteristics of polymeric solution. This study has examined the effect of the nozzle sizes on the diameter of the fibers of 12% polyetherimide (PEI) solution using as solvent dimethyl acetamide Itetrahydrofuran (DMAC/THF), 1:1 ratio. The polymer solution was processed at two values of nozzle size, and the voltage, feed rate and spinning distance were also varied. Processing with different parameters resulted in the production of fibers with diameters varying between 208 and 738nm. When the diameter of the nozzle size of the needle decreases, the surface tension of the drop increases and diminishes the resulted fibers diameter.

Mircea O.,Al. I. Cuza University | Sandu I.,Al. I. Cuza University | Vasilache V.,Al. I. Cuza University | Sandu A.V.,Romanian Inventors Forum | Sandu A.V.,Technical University Gheorghe Asachi
Microscopy Research and Technique | Year: 2012

This article presents the atypical formations in the structure of the corrosion crust and in the partially mineralized metallic core, which resulted during the underground stay of a bronze shield, dated between the 1st century B.C. and the 1st century A.D. For our study, we choose a representative fragment from the rim of the shield, which was analyzed by optical microscopy and by electron microscopy coupled with energy-dispersive X-ray spectroscopy, to study its morphology, its composition, and the location of chemical compounds on the surface and inside the bulk formed during the underground stay, by processes of chemical and physical alteration, assisted by contamination with structural elements from the site. Those processes, by monolithization and mineralization formed a series of structures consisting of congruent elements and phases with a complex composition. Those formations, defined as surface effects generated by exogenous factors and endogenous factors inside the bulk, are frequently found in ancient bronze objects (such as the exterior flat mole formations and the Liesegang effect in the stratigraphic structure of the bulk). Some of those structures have atypical characteristics as regards their structure, composition, and formation mechanism, which may be used in archeometry. Moreover, that includes the object in the category of special cases, in terms of artifact evolution during underground stay and of the atypical formations resulted from the action of pedological and environmental factors. © 2012 Wiley Periodicals, Inc.

Manea L.R.,Technical University Gheorghe Asachi | Manea L.R.,Al. I. Cuza University | Danu M.C.,University of Bacau | Sandu I.,Romanian Inventors Forum | Sandu I.,Al. I. Cuza University
Revista de Chimie | Year: 2015

Producing nanomaterials is a major priority in the European and international research. Given their large surface and porosity, fibers are successfully used in various medical applications (artiricial organs, biomedical applications, prostheses etc.), cosmetics, filtering mediums, absorbent layers in protection clothes etc. A series of technological, constructive and environmental factors have a synergetic action on the electrospinning process. The present work proposes to study the influence of technological factors for the electrospinning process, on fiber diameter in the case of processing the polyetherimide (PEI) in concentration of 12%, using as solvents dimethylacetamide/ tetrahydrofuran (DMAC/THF), 1:1 ratio. The obtained nanofibers were studied by scanning electron microscope, pursueing also the influence of the applied voltage and flow rate on their diameter fibers.

Mircea O.,Roman Museum of History | Sandu I.,Al. I. Cuza University | Sarghie I.,Technical University Gheorghe Asachi | Sandu A.V.,Romanian Inventors Forum
International Journal of Conservation Science | Year: 2010

This paper presents the experiment results obtained by applying non-invasive methods (OM, SEM-EDX, XRF) on metallic artifacts from the 2nd and the 3rd centuries A. D. (discovered in the Vǎleni-Boteşti and Gabǎra-Moldoveni sites, Neamţ County), with components from different overlapped metals (copper/iron), to determine the surface and the internal microstructure (cross-section), corrosion products distribution and the effect of the two metals in the alteration processes. The results revealed some attributes used in authentication, the determination of the conservation state and allowed us to establish proper procedures for the active conservation and the restoration of those artifacts.

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