National Institute for Laser

Bucharest, Romania

National Institute for Laser

Bucharest, Romania
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Vizireanu S.,National Institute for Laser | Ionita M.D.,National Institute for Laser | Ionita R.E.,National Institute for Laser | Stoica S.D.,National Institute for Laser | And 5 more authors.
Plasma Processes and Polymers | Year: 2017

This paper reports on the aging of carbon nanowalls (CNW) and modification of their wettability by the storage time, growth conditions, and post-fabrication plasma treatments. The as-deposited CNW initially exhibit marked hydrophilic behavior (fresh CNW), but within a few days they become highly hydrophobic (aged CNW). Their final hydrophobicity is closely related to their topography which is controlled by the deposition parameters. In addition, subsequent fluorinated plasma treatments result in super-hydrophobic CNW layers, irrespective of the hydrophilic or hydrophobic character of the pre-treated samples. To explain this, we show that the CNW edges contain many defects initially, but such defects become passivated in time. As a result, the surfaces become highly hydrophobic after aging or fluorination, having inert stable terminations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Jang J.H.,University of Florida | Son S.Y.,University of Florida | Lim W.,University of Florida | Phen M.S.,University of Florida | And 3 more authors.
Thin Solid Films | Year: 2010

The new route to fabricate compositionally graded and highly-relaxed Si1-xGex layers using thermal oxidation at high temperatures is investigated. Ge atoms behavior during thermal oxidation of Si1-xGex layers is strongly dependent on the oxidation temperature. For low temperature oxidation processes Ge is incorporated as GeO2 in the grown oxide layer, while for higher temperatures it accumulates below the grown oxide into a layer with a higher concentration than the initial Si1-xGex. However, Si1-xGex layers oxidized at 1000 °C did not show such an accumulation layer because Ge diffusion efficiently occurred, resulting in the formation of a compositionally graded and relaxed Si1-xGex layer. Such layers could be used as virtual substrates for the strained-Si and relaxed-SiGe applications. © 2009 Elsevier B.V. All rights reserved.


PubMed | Federal University of Rio de Janeiro, University of Almeria, Federal University of Fluminense, Federal Rural University of Rio de Janeiro and 3 more.
Type: Journal Article | Journal: Inorganic chemistry | Year: 2016

Binuclear complexes with general formula [Ln


Secu C.E.,National Institute of Materials Physics Bucharest | Matei E.,National Institute of Materials Physics Bucharest | Secu M.,National Institute of Materials Physics Bucharest | Damian V.,National Institute for Laser
Radiation Measurements | Year: 2014

Sol-gel template method has been used to prepare BaFBr:Eu2+ nanophosphor-SiO2 hybrid entrapped within the nanopores array (of about 200 nm size) of a comercial anodized alumina (AA) membrane. Structural and morphological measurements using electron microscopy (SEM) and X-ray diffraction (XRD) have shown the presence of the BaFBr:Eu2+ nanophosphor in the silica xerogel entrapped within the nanopores array; photoluminescence and X-ray excited luminescence measurements have shown Eu 2+ luminescence at 395 nm accompanied by a broad band due to AA membrane. The method assures a relatively uniform spreading of the BaFBr nanophosphor into the AA membrane pores array without the nanoparticles agglomeration. Preliminary imaging tests have shown a spatial resolution in the micrometer range and even in the submicrometer range can be expected. As BaFBr:Eu2+ is a very efficient X-ray phosphor the material might be used as X-ray micro-imaging detector. © 2014 Elsevier Ltd. All rights reserved.


Georgescu N.,National Institute for Laser
IEEE Transactions on Plasma Science | Year: 2011

For water-pollution control, a combined method was used: in situ electrical discharges, ozonized oxygen flow, and a catalyst. The electrical discharges are formed in water, which is inside the ozonized oxygen bubbles. FeCl2 was used as a catalyst (0.25 mmol/L). The streamer discharges in the reactor (with a volume of 1.2 L) were produced with high-voltage pulses. The methylene blue degradation was analyzed from the absorption peak height at 665 nm. In the pollutant-destroying process, an energy efficiency of 9 g/kWh or 8 × 10-9mol/J has been obtained. © 2006 IEEE.


Popa C.,National Institute for Laser | Popa C.,Polytechnic University of Bucharest | Petrus M.,National Institute for Laser | Bratu A.M.,National Institute for Laser
Journal of Biomedical Optics | Year: 2015

Oxidative stress has become an exciting area of schizophrenia (SCZ) research, and provides ample opportunities and hope for a better understanding of its pathophysiology, which may lead to new treatment strategies. The first objective of the present study was to analyze the oxidative stress markers in breath samples of patients with SCZ before and after the treatment with Levomepromazine. The second objective was to analyze the deficiency of amino acids marker in breath samples of patients with SCZ before and after the treatment. Exhaled breath was collected from 15 SCZ patients and 19 healthy controls; subsequently, CO2 laser photoacoustic spectroscopy was used to assess the exhaled breath compounds of the study subjects. One of the main breath biomarkers of the oxidative stress is ethylene, while one of the main breath biomarkers of the amino acids deficiency is ammonia. The breath biomarkers in the exhalation of SCZ patients exhibited significant differences from the breath biomarkers in the exhalation of healthy controls. Analysis of breath ethylene and breath ammonia provides a related model of SCZ exhalation that could represent an effective and convenient screening method for this intellectual disability. © 2015 Society of Photo-Optical Instrumentation Engineers.


Damian C.,Polytechnic University of Bucharest | Crisan A.,Polytechnic University of Bucharest | Vasile T.,National Institute for Laser | Coltuc D.,Polytechnic University of Bucharest | Damian V.,National Institute for Laser
ISSCS 2015 - International Symposium on Signals, Circuits and Systems | Year: 2015

In dispersive spectroscopy, the measurements tend to be drowned in noise because of poor lighting conditions. Hadamard spectroscopy is a technique that allows better Signal-to-Noise Ratios (SNR) for the measurements. In this paper, we propose a method for measuring the gain in SNR of the experimental model of a Hadamard spectroscope. The instrument addresses THz range spectroscopy but, in order to identify the implementation problems, some first experiments are done in visible domain. The noise is measured in dispersive and Hadamard configurations by using an estimator with a precision of 95% and a gain in SNR is calculated. The obtained gain is 3.52, well below the theoretical Fellgett advantage of 5.68. The reason of the poor gain is the detector behavior that has a higher noise level at high intensity radiation. © 2015 IEEE.


Secu M.,National Institute of Materials Physics Bucharest | Secu C.E.,National Institute of Materials Physics Bucharest | Sima M.,National Institute of Materials Physics Bucharest | Negrea R.F.,National Institute of Materials Physics Bucharest | And 3 more authors.
Journal of Luminescence | Year: 2013

Sol-gel chemistry within the pores of a polycarbonate template membrane was used for the preparation of Eosin Y-SiO2 hybrid nano- and microrods, using tetraethylorthosilicate [TEOS, Si(OC2H5) 4] as the precursor in the presence of trifluoroacetic acid (TFA) catalyst. The ethanolic solution of Eosin-Y was added to the silica sol to trap dye molecules inside the SiO2 gel network during the gelation. Structural and morphological characterization using scanning electron microscopy (SEM) and luminescence microscopy have shown the formation of rods with 200 nm and 1.2 μm diameter and about 30 μm length, exhibiting luminescence properties. Spectroscopic characterization has shown that the luminescence is due to Eosin-Y molecule in the xerogel porous network, surrounded by a solvation shell given mainly by the water. © 2013 Elsevier B.V.


Goktas H.,Middle East Technical University | Kirkici H.,Auburn University | Oke G.,Middle East Technical University | Udrea M.,National Institute for Laser
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015

Generation of intense electron beams by superposing two discharges, namely a low pressure dc glow discharge and a high current pulsed discharge at pressures and voltages very similar to that of the pseudo-spark gap devices, has been reported previously [1, 2]. The small diameter, high peak current and short pulse length are the characteristics of the electron beam generated using this technique. In this technique, no high vacuum facilities are necessary, and many applications such as micro processing, X-rays generation, preionization for high-power lasers are feasible. The electron beam current is in the range of 10-30 A. A full characterization of the electron beam that is utilized in this work has been given in a previous work [3]. In this work it is reported that the most energetic part of the electron beam is about 5-nanosecond pulse duration. The beam is magnetically deflected to the specific point. The pulse repetition rate is up to 100 Hz. Microprocessing as drilling tenths of microns diameter holes in different materials such as copper, titanium, tantalum has been performed. The microstructure of the irradiated materials has been investigated by means of SEM and AFM. Currently, the possibility of processing a matrix of holes is being considered. In this paper, preliminary studies regarding the interaction of intense short electron beams with different metallic targets are presented. The electron generator consists of a fast filamentary discharge in low-pressure gases, and the filling gases such as helium, argon, or nitrogen at approximately 0.1 Torr pressure is utilized. Some of the important characteristics of the device for t drilling and micro-machining are that the target can be easily changed, and the beam can be deflected by means of magnetic field. The device is capable of drilling micron holes in metallic targets. After the initial device characterization, several holes at different experimental conditions were drilled onto the target materials, and the interaction of the beam with these different targets was investigated by means of a scanning electron microscope. © 2002 IEEE.


PubMed | Polytechnic University of Bucharest and National Institute for Laser
Type: Journal Article | Journal: Journal of biomedical optics | Year: 2015

Oxidative stress has become an exciting area of schizophrenia (SCZ) research, and provides ample opportunities and hope for a better understanding of its pathophysiology, which may lead to new treatment strategies. The first objective of the present study was to analyze the oxidative stress markers in breath samples of patients with SCZ before and after the treatment with Levomepromazine. The second objective was to analyze the deficiency of amino acids marker in breath samples of patients with SCZ before and after the treatment. Exhaled breath was collected from 15 SCZ patients and 19 healthy controls; subsequently, CO2 laser photoacoustic spectroscopy was used to assess the exhaled breath compounds of the study subjects. One of the main breath biomarkers of the oxidative stress is ethylene, while one of the main breath biomarkers of the amino acids deficiency is ammonia. The breath biomarkers in the exhalation of SCZ patients exhibited significant differences from the breath biomarkers in the exhalation of healthy controls. Analysis of breath ethylene and breath ammonia provides a related model of SCZ exhalation that could represent an effective and convenient screening method for this intellectual disability.

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