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Pop M.N.,Romanian Institute of Isotopic And Molecular Technology
Sensors and Actuators, A: Physical | Year: 2017

A fully digitally adjustable sensor signal conditioning circuit (SCC) is proposed herein. The SCC is meant to properly adjust the input signal delivered either by active sensors or by passive sensors (e.g. thermocouples, piezoelectric and/or pyroelectric sensors, etc.). The circuit is meant to be resistively connected to the sensor that delivers a signal containing low frequency components, ranging from direct current (DC) to 2 × 103 Hz. The signal conditioning circuit is mainly based on one or two inverting stages, each provided with the possibility to digitally control both the gain coefficient (GC) and the direct current (DC) offset. The GC of each stage can be adjusted in a range spanning from sub-unitary to supra-unitary values, therefore the signal conditioning circuit can be used to preserve the dynamic range of an analog to digital converter (ADC) in an optimum domain, while avoiding saturation, also when the input signal is within the dynamic range of the SCC's input but out of the dynamic range necessary at output. The circuit is designed to detain a low-pass characteristic, thus eliminating high frequency components; therefore it provides a basic bandwidth control. A digital to analog conversion stage is employed to adjust the DC offset and to run self-calibration and self- test procedures. The proposed circuit is meant as a basic building block, employed to interface a wide range of sensor signals in order to provide optimal levels for the ADC stage, or to be inserted in an analog signal chain, where signal level conversion may be achieved (for example signal expansion or compression from 0–5 V voltage levels to 0–3.3 V levels). Alternatively, the proposed SCC could be inserted into more specialized data acquisition systems providing a digital system with the ability to self-condition the input signal before acquiring it. The developed SCC prototype has been employed for separating efficiently small temperature and magnetic field's intensity (very low frequency) sensor signals from the continuous components and for best fitting the dynamic range of an ADC. An automatic parameters adjustment algorithm, with no loss of the output signal has been implemented. © 2017 Elsevier B.V.

David E.,Romanian Institute of Isotopic And Molecular Technology | Kopac J.,University of Ljubljana
Journal of Hazardous Materials | Year: 2012

A simple method with high efficiency for generating high pure hydrogen by hydrolysis in tap water of highly activated aluminum dross is established. Aluminum dross is activated by mechanically milling to particles of about 45μm. This leads to removal of surface layer of the aluminum particles and creation of a fresh chemically active metal surface. In contact with water the hydrolysis reaction takes place and hydrogen is released. In this process a Zero Waste concept is achieved because the other product of reaction is aluminum oxide hydroxide (AlOOH), which is nature-friendly and can be used to make high quality refractory or calcium aluminate cement. For comparison we also used pure aluminum powder and alkaline tap water solution (NaOH, KOH) at a ratio similar to that of aluminum dross content. The rates of hydrogen generated in hydrolysis reaction of pure aluminum and aluminum dross have been found to be similar. As a result of the experimental setup, a hydrogen generator was designed and assembled. Hydrogen volume generated by hydrolysis reaction was measured. The experimental results obtained reveal that aluminum dross could be economically recycled by hydrolysis process with achieving zero hazardous aluminum dross waste and hydrogen generation. © 2012 Elsevier B.V.

Yacob Z.,Romanian Institute of Isotopic And Molecular Technology | Nan A.,Romanian Institute of Isotopic And Molecular Technology | Liebscher J.,Romanian Institute of Isotopic And Molecular Technology | Liebscher J.,Humboldt University of Berlin
Advanced Synthesis and Catalysis | Year: 2012

Novel magnetically tagged organocatalysts have been developed based on core-shell nanoparticles consisting of magnetite cores and polyacrylate shells containing 4-hydroxyproline moieties. These catalysts allow the performance of direct asymmetric aldol reactions of aromatic aldehydes with ketones in the presence of benzoic acid providing high yields and ees. Straightforward magnetic separation and recycling of a catalyst for up to 9 runs is possible without a significant loss of efficiency. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dadarlat D.,Romanian Institute of Isotopic And Molecular Technology | Pop M.N.,Romanian Institute of Isotopic And Molecular Technology
International Journal of Thermal Sciences | Year: 2012

The front photopyroelectric (FPPE) configuration, together with the thermal-wave resonator cavity (TWRC) method was applied in order to measure both thermal effusivity and diffusivity of liquids. The methodology is based on a 4-layer detection cell (pyroelectric sensor, coupling fluid, solid separator and liquid backing) in which the investigated liquid is inserted successively in backing and in coupling fluid's position, respectively. When inserted in the backing position a scan of the phase of the FPPE signal as a function of (a known) coupling fluid's thickness (TWRC method) leads to the direct measurement of liquid's thermal effusivity. Inserting then the investigated liquid in coupling fluid's position (with a known backing liquid), a similar thickness scan leads to the measurement of its thermal diffusivity. In such a way the FPPE-TWRC method becomes self-consistent; all static and dynamic thermal parameters can be derived with the same technique (two of them are directly measured and the remaining two, calculated). The suitability of the method was demonstrated with investigations on several liquids as water, ethylene glycol, glycerine, various oils. © 2012 Elsevier Masson SAS. All rights reserved.

Garabagiu S.,Romanian Institute of Isotopic And Molecular Technology | Mihailescu G.,Romanian Institute of Isotopic And Molecular Technology
Journal of Electroanalytical Chemistry | Year: 2011

In this work we propose the design of an electrochemical setup (hemoglobin-gold-nanoparticles-ITO glass), used for the determination of a hemoglobin adduct (acrylamide). Acrylamide is neurotoxin and potential carcinogen, formed mainly in high temperatures processed food that contains large quantity of starch (French fries, baked bread). Acrylamide forms hemoglobin adducts, and our sensing device is based on this property, by passivating the hemoglobin-modified electrode by the addition of low concentrations of acrylamide. The sensitivity to acrylamide better as 0.1 μM makes this electrochemical cell configuration suitable for the detection of acrylamide in food products. © 2011 Elsevier B.V. All rights reserved.

Bogdan D.,Romanian Institute of Isotopic And Molecular Technology | Morari C.,Romanian Institute of Isotopic And Molecular Technology
Journal of Physical Chemistry C | Year: 2012

The geometrical properties and electronic structure of single DNA nucleosides (deoxyadenosine, deoxythymidine, deoxyguanosine, deoxycytidine) adsorbed on a metallic surface of Au(100) are determined using density functional theory computations. We investigate multiple adsorption geometries and the resulting molecule-surface interaction mechanisms. For adenosine, we found negligible differences between the binding energy in the two configurations investigated by us, while for guanosine this difference reaches the maximum value among the four nucleosides (i.e., 0.38 eV). The projected density of states indicates that the physisorption is the main cause of the binding energy. Nevertheless, for the adsorbed deoxycytosine (dC), we point out the presence of the chemical interaction too. While the absolute values of the molecule-surface charge transfer are small, they are qualitatively dependent on the orientation of the nucleosides to the surface. If the DNA bases are oriented perpendicular to the surface, the electronic population of molecules decreases, while the parallel orientation of the DNA bases with respect to metal surface leads to an increase of electronic population on the molecules. © 2012 American Chemical Society.

Turcu I.,Romanian Institute of Isotopic And Molecular Technology | Bogdan M.,Romanian Institute of Isotopic And Molecular Technology
Journal of Physical Chemistry B | Year: 2012

One of the most important purposes in molecular technologies is the preparation of supramolecular structures by self-assembling processes. The aromatic molecules self-associate mainly in π-π stacked structures with an aggregate size distribution determined by the association equilibrium constants. A general expression for the equilibrium constants Kn,m which govern the self-association of two aggregates with n and m monomers respectively has been obtained. The model predicts also the concentrations of free monomers, the concentrations of n-mers, and the total concentration of aggregates. 1H NMR experiments have been used to illustrate the applicability of the proposed model in a particular case: π-stacking self-association of ciprofloxacin in solution. © 2012 American Chemical Society.

Pop M.N.,Romanian Institute of Isotopic And Molecular Technology
International Journal of Thermal Sciences | Year: 2016

A stacked three layer monolithic sub-system comprising a pyroelectric (PE) sensor, a thermal coupling layer and an external plate (EP), intended to detain a rigid, corrosion resistant external surface and to be used in front detection configuration for liquid samples' thermal parameters measurement is proposed herein. The thermal waves (TWs) are generated on the irradiated surface of the PE material and after propagating through the sensor and the coupling layer reach the EP. The EP, positioned in contact with the liquid sample is intended to act as a buffer layer (protective against mechanical and corrosion agents) while successfully transmitting the probing TWs to the investigated semi-infinite sample. The normalized signal can be described by means of an analytical model obtained by assuming one-dimensional TWs propagation through the five layered system: air/proposed sub-system and backing liquid sample. The theoretical signal is firstly analyzed by studying the numerical behaviour of the normalized amplitude and phase and the behaviour of the sensitivity coefficients specific to these components when the thermal effusivity of a semi-infinite liquid is aimed to be extracted. The experimental results obtained by performing frequency scanning measurements using a composite sub-system with a brass EP and different backing sample liquids are presented. © 2016 Elsevier Masson SAS. All rights reserved.

Buimaga-Iarinca L.,Romanian Institute of Isotopic And Molecular Technology | Morari C.,Romanian Institute of Isotopic And Molecular Technology
RSC Advances | Year: 2013

Cysteine clusters of various sizes are investigated, as free structures and adsorbed on the Au(110)-(1 × 1) surface, by using density-functional theory. We analyse the adsorption of clusters in protonized and deprotonized forms. The presence of a trend for the values of bonding energy per adsorbed cysteine molecule as a function of cluster size is pointed out. To explain these findings we analyse the electronic density of states of the clusters and the charge transfer occurring between the surface and cysteine molecules. We emphasize the broadening of the molecular density of states as a function of cluster size. Details of the geometrical structure of the adsorbed clusters in protonized and deprotonized forms are compared and discussed from the perspective provided by the electronic structure calculation. By investigating the redistribution of the electron density upon the adsorption we point out the significant features of the molecule-surface charge transfer. In particular we show that the charge redistribution occurs only at the thiol end while the electronic density of the carboxylic group is not affected in the adsorbed state. © 2013 The Royal Society of Chemistry.

Garabagiu S.,Romanian Institute of Isotopic And Molecular Technology
Journal of Molecular Structure | Year: 2013

The interactions between nanostructures and biomolecules are intensely studied. Noble metal nanoparticles can modify the optical response of macromolecules. In this study, we analyzed by spectroscopic methods (UV-Vis Spectroscopy, Steady State Fluorescence, and FTIR) the bio-conjugation of horse hemoglobin with gold nanorods. Upon the formation of the gold nanorods-hemoglobin complex, the fluorescence signal increases, through Metal-enhanced fluorescence phenomenon. © 2012 Elsevier B.V. All rights reserved.

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