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Showing papers by "Romanian Academy published in 2003"


Journal ArticleDOI
TL;DR: In this paper, the antibacterial activity of nanostructured Fe3+-doped coatings was investigated using X-ray diffraction and spectroellipsometry methods.

199 citations


Journal ArticleDOI
TL;DR: In this article, the authors compared the long-term fate and environmental significance of contaminant metals released by mine tailings dam failures in Maramures County, northwest Romania, and concluded that metal contamination in surface water and river sediment decreases rapidly downstream away from presently active mines and tailings ponds.

186 citations


Journal ArticleDOI
TL;DR: In this paper, the evolution of the electrode surface was examined by optical microscope and the results indicated that, Tween 20 and 81 are more effective to inhibit the corrosion of pure aluminium than hexadecylpyridinium bromide (HDPB) under the critical micelle concentration (CMC), the inhibition of used surfactants is negligible.

161 citations


Journal ArticleDOI
TL;DR: In this paper, a relation between the topology of hypersurface complements, Milnor fibers and degree of gradient mappings is described, and it is shown that affine parts of projective hypersurfaces have affine Lefschetz theory.
Abstract: We describe a new relation between the topology of hypersurface complements, Milnor fibers and degree of gradient mappings. In particular we show that any projective hypersurface has affine parts which are bouquets of spheres. The main tools are the polar curves and the affine Lefschetz theory developped by H. Hamm, D.T. L\^e and A. N\'emethi. In the special case of the hyperplane arrangements, we strengthen some results due to Orlik and Terao (see Math. Ann. 301(1995)) and obtain the minimality of hyperplane arrangements (see Randell math.AT/0011101 for another proof of this result). This is then used to compute some higher homotopy groups of hyperplane arrangements using the ideas from Papadima-Suciu, see math.AT/0002251. The second version contains applications of the above ideas to the polar Cremona transformations and gives a positive answer to Dolgachev's Conjecture (see Michigan Math. J. 48 (2000), volume dedicated to W. Fulton). The third version corrects some errors and provides new applications.

114 citations


Journal ArticleDOI
TL;DR: In this article, the synthesis and characterization of compounds with antibacterial activity: quaternary phosphonium salts grafted on macromolecular supports by polymer-analogous reactions.
Abstract: This paper deals with the synthesis and characterization of compounds with antibacterial activity: quaternary phosphonium salts grafted on macromolecular supports by polymer-analogous reactions. The products were proved to have antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. A great advantage was that the active species grafted on insoluble carriers could be used in repeated cycles, only needing sterilization prior to use.

112 citations


Journal ArticleDOI
TL;DR: In this article, solid state partitioning of metals and As in river channel sediments has been investigated along an 828 km study reach comprising the rivers Lapus, Somes and Tisa, using a 4-stage sequential extraction procedure (SEP) that identified 4 chemical phases: (1) exchangeable, (2) Fe and Mn oxides, (3) organic matter/sulphides and (4) residual.

108 citations


Journal ArticleDOI
TL;DR: In this article, a study of carbon dioxide reduction at RuO2-coated diamond electrodes showed that conductive metallic oxides are promising electrocatalysts for this process and allow higher reduction products to be obtained.
Abstract: Study of carbon dioxide reduction at RuO2-coated diamond electrodes showed that conductive metallic oxides are promising electrocatalysts for this process and allow higher reduction products to be obtained. The main reduction products obtained in acidic and neutral media were formic acid and methanol, with product efficiencies as high as 40 and 7.7%, respectively. It was observed that conductive diamond is a very well suited material for studying the electrocatalytic properties of conductive metallic oxides, because its use resulted in a negligible substrate effect. This feature will greatly enhance the ability to understand the relationships between the intrinsic electrochemical behavior and the electrocatalytic behavior, in view of developing new effective electrocatalysts. The use of conductive diamond could also allow better utilization of the electrocatalyst by avoiding the need for thick films.

95 citations


Book ChapterDOI
17 Jul 2003
TL;DR: This paper implements the simplest variant of P systems, which however defines the essential features of the membrane systems, and acts as a framework for other variants of P system with advanced functionalities.
Abstract: The paper presents a parallel implementation of the membrane systems. We implement the simplest variant of P systems, which however defines the essential features of the membrane systems, and acts as a framework for other variants of P systems with advanced functionalities. The mechanisms used in this implementation could be easily adapted to other versions of P systems with minor changes. The implementation is designed for a cluster of computers; it is written in C++ and it makes use of Message Passing Interface as its communication mechanism.

83 citations


Journal ArticleDOI
TL;DR: In this paper, a 12% Ru/Al2O3 catalyst was prepared by deposition of relatively monodispersed colloidal Ru nanoparticles of about 5.8 nm on alumina.

82 citations


Journal ArticleDOI
TL;DR: In this article, the absolute proper motions of four low-latitude, inner Galaxy globular clusters are measured and the proper motions are on the Hipparcos system, since no background extragalactic objects are found in these high extinction regions.
Abstract: We have measured the absolute proper motions of four low-latitude, inner Galaxy globular clusters. These clusters are NGC 6266 (M62), NGC 6304, NGC 6316, and NGC 6723. The proper motions are on the Hipparcos system, since no background extragalactic objects are found in these high-extinction regions. The proper-motion uncertainties range between 0.3 and 0.6 mas yr � 1 . We discuss the kinematics of these clusters and of three additional bulge clusters—NGC 6522, NGC 6528, and NGC 6553—whose proper motions with respect to bulge stars had been determined previously. We find that all of the clusters have velocities that confine them to the bulge region. Of the three metal-poor clusters ([Fe/H] < � 1.0), NGC 6522, and NGC 6723 have kinematics consistent with halo membership. The third cluster, NGC 6266 however, appears to belong to a rotationally supported system. Of the four metal-rich clusters ([Fe/H] �� 1.0), NGC 6304 and NGC 6553 also have kinematics consistent with membership to a rotationally supported system. NGC 6528 has kinematics, metallicity, and mass that argue in favor of a genuine Milky Way bar cluster. NGC 6316’s kinematics indicate membership to a hotter system than the bar.

81 citations


Journal ArticleDOI
TL;DR: In this paper, the surface density of the Galactic disk in the solar neighborhood within ± 0.4 kpc of the Sun using the parallaxes and proper motions of a kinematically and spatially unbiased sample of 1476 old bright red giant stars from the Hipparcos catalog with measured radial velocities from Barbier-Brossat & Figon.
Abstract: We have reestimated the surface density of the Galactic disk in the solar neighborhood within ±0.4 kpc of the Sun using the parallaxes and proper motions of a kinematically and spatially unbiased sample of 1476 old bright red giant stars from the Hipparcos catalog with measured radial velocities from Barbier-Brossat & Figon. We determine the vertical distribution of the red giants as well as the vertical velocity dispersion of the sample (14.4 ± 0.3 km s-1) and combine these to derive the surface density of the gravitating matter in the Galactic disk as a function of the Galactic coordinate z. The surface density of the disk increases from 10.5 ± 0.5 M⊙ pc-2 within ±50 pc to 42 ± 6 M⊙ pc-2 within ±350 pc. The estimated volume density of the Galactic disk within ±50 pc is about 0.1 M⊙ pc-3 which is close to the volume density estimates of the observed baryonic matter in the solar neighborhood.

Journal ArticleDOI
TL;DR: In this paper, a reliable entanglement measure for a two-mode squeezed thermal state of the quantum electromagnetic field in terms of its Bures distance to the set of all separable states of the same kind was proposed.
Abstract: We propose a reliable entanglement measure for a two-mode squeezed thermal state of the quantum electromagnetic field in terms of its Bures distance to the set of all separable states of the same kind. The requisite fidelity of a pair of two-mode squeezed thermal states is exactly evaluated. By applying the Peres-Simon criterion of separability, we find the closest separable state. This enables us to establish an insightful expression of the amount of entanglement. We also derive the relative entropy of a two-mode squeezed thermal state with respect to another one. This quantity is exploited in the pure-state case by undertaking a similar approximation for the entropic entanglement of a two-mode squeezed vacuum state. Comparison with previous work lends support to our approach that replaces the reference set of all separable Gaussian states by its subset consisting only of the squeezed thermal ones.

Journal ArticleDOI
TL;DR: In this article, the shape and size of the Pt nanoparticles obtained by reduction of K2PtCl4 solution in the presence of different capping polymers were found to be related to the kind of capping polymer used.
Abstract: Platinum nanoparticles with different morphology were prepared by reduction of K2PtCl4 solution in the presence of different capping polymers. It was found that the shapes and the sizes of the Pt nanocrystals resulted were related to the kind of capping polymer used. When poly(vinylpyrrolidon) (PVP), poly(N-isopropylacrylamide) (NIPA) and sodium poly(acrylate) (SPA) were used as capping agents, the dominant shapes of the Pt nanocrystals observed by transmission electron microscopy were hexagonal (≈62%), square (≈67%) and triangular (≈41%), respectively. The average sizes of Pt nanocrystals were 6.9, 13.6 and 14.6 nm for capping polymers of PVP, NIPA and SPA, respectively. The colloidal Pt nanoparticles with different morphologies were supported on γ-Al2O3 (1 wt.% Pt) and then their catalytic activity for NO reduction by CH4 was tested in the 350–600°C temperature range. Additionally, the catalytic activities of these alumina-supported Pt nanocrystals were compared with a conventional catalyst having the average size of Pt particles of ≈2.4 nm. Over the alumina-supported Pt nanocrystals as compared with the conventional Pt/Al2O3, it was observed that the NO/CH4 reaction yields to NH3 and CO decreased significantly and on the other hand, the yield to N2O increased. The experimental results are suggesting that the catalytic behavior can be tuned in a convenient way through the morphological control of the metal nanoparticles.

Journal ArticleDOI
01 Aug 2003-Polymer
TL;DR: In this paper, a number of polyurethanes are synthesized, based on the novel diisocyanate 4,4′-dibenzyl diisOCyanate (DBDI), or combinations of these, and X-ray crystallinity data are shown for the materials as prepared and after annealing.

Journal ArticleDOI
TL;DR: In this paper, a generalized form of the random walk algorithm is introduced to simulate diffusion processes, where at a given time all the particles from a grid node are simultaneously scattered using the Bernoulli repartition.

Journal ArticleDOI
TL;DR: The aim of this paper is to point out certain shortcomings in the work of Dutta et al. and give the correct proof of theorem which validates the obtaining of the efficient solutions of MOLFPP.

Journal ArticleDOI
TL;DR: In this article, the authors used geometrically defined divisors on moduli spaces of pointed curves to compute the graded Betti numbers of general sets of points on any nonhyperelliptic canonically embedded curve.
Abstract: We use geometrically defined divisors on moduli spaces of pointed curves to compute the graded Betti numbers of general sets of points on any nonhyperelliptic canonically embedded curve. This gives a positive answer to the Minimal Resolution Conjecture in the case of canonical curves. But we prove that the conjecture fails on curves of large degree. These results are related to the existence of theta divisors associated to certain stable vector bundles.

Journal ArticleDOI
TL;DR: In this paper, a correction force term is introduced to eliminate the spurious interface velocity in finite difference lattice Boltzmann models for liquid-vapor systems, which helps to recover sharp interfaces and sets the phase diagram close to the one derived using the Maxwell construction.
Abstract: The origin of the spurious interface velocity in finite difference lattice Boltzmann models for liquid–vapor systems is related to the first order upwind scheme used to compute the space derivatives in the evolution equations. A correction force term is introduced to eliminate the spurious velocity. The correction term helps to recover sharp interfaces and sets the phase diagram close to the one derived using the Maxwell construction.

Posted Content
TL;DR: In this article, the splitting dimension and the splitting ratio of a reduced F-finite ring R of characteristic p > 0 and q=p^e were studied in detail, and it was shown that R/P(R) is strongly F-regular.
Abstract: For a reduced F-finite ring R of characteristic p >0 and q=p^e one can write R^{1/q} = R^{a_q} \oplus M_q, where M_q has no free direct summands over R. We investigate the structure of F-finite, F-pure rings R by studying how the numbers a_q grow with respect to q. This growth is quantified by the splitting dimension and the splitting ratios of R which we study in detail. We also prove the existence of a special prime ideal P(R) of R, called the splitting prime, that has the property that R/P(R) is strongly F-regular. We show that this ideal captures significant information with regard to the F-purity of R.

Journal ArticleDOI
TL;DR: In this article, the authors explore an accretion origin for ω Cen by N-body modeling of the orbital decay and disruption of a Milky Way dwarf satellite, which is launched from 58 kpc from the Galactic center, on a radial low-inclination orbit.
Abstract: We explore an accretion origin for ω Cen by N-body modeling of the orbital decay and disruption of a Milky Way dwarf satellite. This work is focused on studying a particular satellite model that aims to reproduce the present orbit of ω Cen, as recently determined from absolute proper motions. The model satellite is launched from 58 kpc from the Galactic center, on a radial low-inclination orbit. We find that a capture scenario can produce an ω Cen-like object with the current low-energy orbit of the cluster. Our best model is a nucleated dwarf galaxy with a Hernquist density profile that has a mass of 8 × 109 M☉ and a half-mass radius of 1.4 kpc.

Journal ArticleDOI
TL;DR: In this paper, the thermal and thermo-oxidative properties of binary isotactic polypropylene (IPP)/polyamide 6 (PA6) and ternary IPP/PA6/ethylene-propylene diene terpolymer (EPDM) blends in various ratios were obtained in a Haake Rheocord mixer.

Journal ArticleDOI
TL;DR: In this article, it was shown that the space of mathematical instantons with second Chern class 5 over ℙ3 is smooth and irreducible, and simple proofs for the same statements in case of second Chern ≤ 4 are contained.
Abstract: We prove that the space of mathematical instantons with second Chern class 5 over ℙ3 is smooth and irreducible. Unified and simple proofs for the same statements in case of second Chern class ≤ 4 are contained.

Journal ArticleDOI
TL;DR: In this paper, two polyurethane-epoxy maleate of bisphenol A networks were synthesized and their thermal behavior was studied, and the data obtained by thermogravimetry showed that the decomposition of the tested samples is complex, occurs in three steps, and depends on the degree of crosslinking.

Journal ArticleDOI
TL;DR: In this paper, the authors consider a billiard in the punctured torus obtained by removing a small disk of radius ǫ>0 from the flat torus, with trajectory starting from the center of the puncture, where the phase space is given by the range of the velocity ω only.
Abstract: We consider a billiard in the punctured torus obtained by removing a small disk of radius ɛ>0 from the flat torus 𝕋2, with trajectory starting from the center of the puncture. In this case the phase space is given by the range of the velocity ω only. Let ˜τɛ(ω), and respectively ˜Rɛ(ω), denote the first exit time (length of the trajectory), and respectively the number of collisions with the side cushions when 𝕋2 is being identified with [0,1)2. We prove that the probability measures on [0,∞) associated with the random variables ɛ˜τɛ and ɛ˜Rɛ are weakly convergent as ${{\varepsilon \rightarrow 0^+}}$ and explicitly compute the densities of the limits.

Journal ArticleDOI
TL;DR: A Probabilistic P system simulator that implements the evolution-communication model proposed in Cavaliere, 2003 enriched with some probabilistic parameters inspired by the cell biology is presented.
Abstract: In this paper we present a probabilistic P system simulator that implements the evolution-communication model proposed in (Cavaliere, 2003) enriched with some probabilistic parameters inspired by the cell biology. After describing the software and its working, we compare the mathematical model used with the biological reality of the cell. Then, we present some mathematical and biological applications showing how one can use this software to simulate simple but interesting biological phenomena, related to respiration and photosynthesis processes in some bacteria.

Journal ArticleDOI
TL;DR: Two binuclear complexes of copper(II), [(Hfsaaep)Cu(μ-C 2 O 4 )Cu(HFSaaep)] ( 1 ) and [Cu 2 (Hfsadmpn) 2 ( H 2 O) 2 ](ClO 4 ) 2 ( 2 ) have been synthesized by using Schiff-base ligands derived from 3-formyl-salicylic acid: 3-[ N -2-(pyridylethyl)formimidoyl]salicyric acid (H 2 fsaaep), and

Journal ArticleDOI
TL;DR: Using pulse-chase experiments, it is shown that the TRP-2 polypeptide folds in the endoplasmic reticulum in the presence of calnexin, until it reaches a dithiothreitol-resistant conformation enabling its ER exit to the Golgi.

Journal ArticleDOI
TL;DR: In this article, the magnetic behavior of noninteracting γ-Fe 2 O 3 nanoparticles dispersed in a silica matrix is superparamagnetic, and the appearance of the hysteresis loop is attributed to the Neel magnetic relaxation processes; the easy magnetisation axes of the nanoparticles being randomly oriented, the magnetic moments will rotate in an external magnetic field with a relaxation time τ, which depends on the effective anisotropy constant K eff.
Abstract: At room temperature the magnetic behaviour of non-interacting γ-Fe 2 O 3 nanoparticles dispersed in a silica matrix is superparamagnetic. At a lower temperature (77 K) hysteresis was observed. The appearance of the hysteresis loop is attributed to the Neel magnetic relaxation processes; the easy magnetisation axes of the nanoparticles being randomly oriented, the magnetic moments will rotate in an external magnetic field with a relaxation time τ , which depends on the effective anisotropy constant K eff . A supplementary anisotropy, e.g. stress anisotropy and the surface anisotropy leads to a total value ( K eff ), approximately 10 times higher than the bulk magnetocrystalline anisotropy K . At the surface of embedded nanoparticles a modification of the superexchange interaction takes place—due to specific particle-matrix interactions—on decreasing the temperature from 300 to 77 K; the magnetic moment of the particles increases 1.6 times. This behaviour can be attributed to the increase of the nanoparticles magnetic core volume of aligned spins and is not due to the variation of the spontaneous magnetisation with temperature.

Journal ArticleDOI
TL;DR: In this article, a pyrylium salt is formed via diacylation of alkenes, which is then converted by primary amines into pyridinium salts.

Journal ArticleDOI
TL;DR: The study of P systems with string objects processed by rewriting rules, by investigating some questions which are classic in formal language theory: leftmost derivation, conditional use of rules (permitting and forbidding conditions), relationships with language families in Chomsky and Lindenmayer hierarchies.