Showing papers by "Romanian Academy published in 2007"
TL;DR: Microbial enhanced oil recovery (MEOR) as mentioned in this paper represents the use of microorganisms to extract the remaining oil from reservoirs, which has the potential to be cost-efficient in the extraction of oil remained trapped in capillary pores of the formation rock or in areas not swept by the classical or modern enhanced OOR methods, such as combustion, steams, miscible displacement, caustic surfactant-polymers flooding, etc.
Abstract: Microbial enhanced oil recovery (MEOR) represents the use of microorganisms to extract the remaining oil from reservoirs. This technique has the potential to be cost-efficient in the extraction of oil remained trapped in capillary pores of the formation rock or in areas not swept by the classical or modern enhanced oil recovery (EOR) methods, such as combustion, steams, miscible displacement, caustic surfactant-polymers flooding, etc. Thus, MEOR was developed as an alternative method for the secondary and tertiary extraction of oil from reservoirs, since after the petroleum crises in 1973, the EOR methods became less profitable. Starting even from the pioneering stage of MEOR (1950s) studies were run on three broad areas, namely, injection, dispersion, and propagation of microorganisms in petroleum reservoirs; selective degradation of oil components to improve flow characteristics; and metabolites production by microorganisms and their effects.
287 citations
TL;DR: FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples and clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed.
Abstract: The main difficulties in wood and pulp analyses arise principally from their numerous components with different chemical structures. Therefore, the basic problem in a specific analytical procedure may be the selective separation of the main carbohydrate-derived components from lignin due to their chemical association and structural coexistence. The processing of the wood determines some structural modification in its components depending on the type of wood and the applied procedure. Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction have been applied to analyze Eucalyptus g. wood chips and unbleached and chlorite-bleached pulp. The differences between samples have been established by examination of the spectra of the fractions obtained by successive extraction (acetone extractives, acetone free extractive samples, hemicelluloses, and lignins) by evaluating the derivative spectra, band deconvolution, etc. The energy and the hydrogen bonding distance have been evaluated. The relationship between spectral characteristics and sample composition has been established, as well as the variation of the degree of crystallinity after pulping and bleaching. The integral absorption and lignin/carbohydrate ratios calculated from FT-IR spectra of the IR bands assigned to different bending or stretching in lignin groups are stronger in the spectrum of eucalyptus chips than those from brown stock (BS) pulp spectra because of the smaller total amount of lignin in the latter. FT-IR spectra clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed. Along with FT-IR data, the X-ray results confirmed the low content of lignin in the pulp samples by increasing the calculated values of the crystalline parameters. It was concluded that FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples.
259 citations
TL;DR: In this paper, a review of NHC-Ru precatalysts in fundamental organic processes is presented, including hydrogenation, hydrogen transfer, cycloisomerization, cyclopropanation, hydrosilylation, allylation and deallylation, enolester synthesis, heterocycle synthesis, C-C alkyne coupling, Kharasch addition and ATRP.
249 citations
TL;DR: In this article, a quadratic bound on the rate of asymptotic regularity for the Krasnoselski-Mann iterations of nonexpansive mappings in CAT(0)-spaces was obtained.
214 citations
TL;DR: In this paper, the authors considered the case of spiking neural P systems (SNP systems), in two variants: as devices that compute functions and as generators of sets of numbers, and they found a universal system with restricted rules having 76 neurons and one with extended rules having 50 neurons.
Abstract: In search for small universal computing devices of various types, we consider here the case of spiking neural P systems (SN P systems), in two variants: as devices that compute functions and as devices that generate sets of numbers. We start with the first case and we produce a universal spiking neural P system with 84 neurons. If a slight generalization of the used rules is adopted, namely, we allow rules for producing simultaneously several spikes, then a considerable reduction, to 49 neurons, is obtained. For SN P systems used as generators of sets of numbers, we find a universal system with restricted rules having 76 neurons and one with extended rules having 50 neurons.
206 citations
TL;DR: In this paper, several combinations of surfactants with different chain lengths (lauric acid, myristic acid (MA), oleic acid and dodecyl-benzene-sulphonic acid (DBS)) were used.
186 citations
TL;DR: In this article, the authors reviewed some recent results concerning chemical synthesis of magnetic nanoparticles and preparation of various types of magnetic nanofluids and emphasized their use in leakage-free rotating seals and in biomedical applications.
176 citations
TL;DR: In this article, a "one pot" facile method for environmentally benign production of stable Ag colloids, using short chain polyethylene glycol as solvent, reducing agent and stabilizer, was reported.
158 citations
TL;DR: Several advanced solutions such as mixed knowledge systems, that combine numerical methods with AI-based tools, and the prospects of using Ambient Intelligence concepts in DSS construction are described.
141 citations
TL;DR: This investigation investigates the relationship between the introduced fish, emergent vegetation cover and native amphibians in man-made ponds generated by regulation and dam building along the Târnava Mare Valley (Romania) during the last 40 years and suggests the restriction of fish introductions to non predatory fish and the maintenance of high emergentenery cover in the ponds.
Abstract: Fish introductions are considered one of the most widespread anthropogenic threats to aquatic ecosystems. Their negative impact on native amphibian communities has received increasing attention in recent years. We investigated the relationship between the introduced fish, emergent vegetation cover and native amphibians in man-made ponds generated by regulation and dam building along the Târnava Mare Valley (Romania) during the last 40 years. We inventoried amphibians and fish inhabiting 85 permanent ponds and estimated habitat complexity focusing on emergent vegetation cover. Four amphibian species were found to be negatively associated with the presence of predatory fish. Species richness of ponds without fish and ponds without predatory fish did not differ significantly, whereas ponds containing only predatory fish had significantly lower amphibian richness. A significant positive relationship was found between the emergent vegetation cover and pond occupancy of six amphibian species and amphibian species richness. As a management recommendation, we suggest the restriction of fish introductions to non predatory fish and the maintenance of high emergent vegetation cover in the ponds.
135 citations
TL;DR: In this paper, it was shown that the subordination results of Voiculescu and Biane can be deduced from a continuity property of fixed points for analytic functions.
Abstract: We show that the subordination results of D. Voiculescu and Ph. Biane can be deduced from a continuity property of fixed points for analytic functions.
TL;DR: In this article, the authors studied a nonlocal convective and diffusive nonlocal equation with respect to the initial condition of solutions and proved existence, uniqueness, and continuous dependence.
TL;DR: The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size.
Abstract: Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature–size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature–size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature–size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 × CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature–size rule, which has puzzled biologists for decades.
TL;DR: For an irrotational unidirectional shallow water flow, this article derived the CamassaHolm equation by a variational approach in the Lagrangian formalism.
Abstract: We describe the physical hypothesis in which an approximate model of water waves is obtained For an irrotational unidirectional shallow water flow, we derive the CamassaHolm equation by a variational approach in the Lagrangian formalism
TL;DR: If at least a rule from a set of rules associated with a membrane or a region can be used, then at least one rule from that membrane or region must be used , without any other restriction, and this minimal parallelism leads to universality.
TL;DR: In this article, the thermogravimetry of textile waste at different heating rates and also by semi-batch pyrolysis was studied by using a parallel model, which proved the existence of complex reaction mechanisms for both cases.
TL;DR: Trends indicate that chemical probes are similar to leads with respect to some properties, e.g., complexity, solubility, and hydrophobicity.
Abstract: Academic and industrial research continues to be focused on discovering new classes of compounds based on HTS. Post-HTS analyses need to prioritize compounds that are progressed to chemical probe or lead status. We report trends in probe, lead and drug discovery by examining the following categories of compounds: 385 leads and the 541 drugs that emerged from them; ''active'' (152) and ''inactive'' (1488) compounds from the Molecular Libraries Initiative Small Molecule Repository (MLSMR) tested by HTS; ''active'' (46) and ''inactive'' (72) compounds from Nature Chemical Biology (NCB) tested by HTS; compounds in the drug development phase (I, II, III and launched), as indexed in MDDR; and medicinal chemistry compounds from WOMBAT, separated into high-activity (5,784 compounds with nanomolar activ- ity or better) and low-activity (30,690 with micromolar activity or less). We examined Molecular weight (MW), molecular complexity, flexibility, the number of hydrogen bond donors and acceptors, LogP—the oct- anol/water partition coefficient estimated by ClogP and ALOGPS), LogSw (intrinsic water solubility, esti- mated by ALOGPS) and the number of Rule of five (Ro5) criteria violations. Based on the 50% and 90% distribution moments of the above properties, there were no significant difference between leads of known drugs and ''actives'' from MLSMR or NCB (chemical probes). ''Inactives'' from NCB and MLSMR were also found to exhibit similar properties. From these com- bined sets, we conclude that ''Actives'' (569 com- pounds) are less complex, less flexible, and more soluble than drugs (1,651 drugs), and significantly smaller, less complex, less hydrophobic and more sol- uble than the 5,784 high-activity WOMBAT com- pounds. These trends indicate that chemical probes are similar to leads with respect to some properties, e.g., complexity, solubility, and hydrophobicity.
TL;DR: In this paper, a simple technique for the preparation of single-phase BiFeO3 powders using the polymerized complex method, starting from iron and bismuth nitrates, was reported.
Abstract: The present investigation reports on a simple technique for the preparation of single-phase BiFeO3 powders using the polymerized complex method, starting from iron and bismuth nitrates. A mixed aqueous solution with citric acid, ethylene glycol, Bi, and Fe ions was polymerized. The formation mechanism, the homogeneity, and the structure of the obtained powders have been investigated by thermogravimetry, X-ray diffraction (XRD), Raman spectroscopy, and scanning and transmission electron microscopy measurements. XRD results demonstrated that thermally induced crystallization of rhombohedral BiFeO3 from the Bi–Fe polymeric precursor occurred at temperatures as low as 400°C. Pure single-phase BiFeO3 nanocrystallites without any impurity or amorphous phases were obtained when the precursor was treated at 600°C for 3 h.
TL;DR: This article measured the absolute proper motions of globular clusters NGC 2808, 3201, 4372, 4833, 5927, and 5986 on the Hipparcos system, and they are the first determinations ever made for these low Galactic latitude clusters.
Abstract: We have measured the absolute proper motions of globular clusters NGC 2808, 3201, 4372, 4833, 5927, and 5986. The proper motions are on the Hipparcos system, and they are the first determinations ever made for these low Galactic latitude clusters. The proper-motion uncertainties range from 0.3 to 0.5 mas yr-1. The inferred orbits indicate that (1) the single metal-rich cluster in our sample, NGC 5927, dynamically belongs to the thick disk; (2) the remaining metal-poor clusters have rather low-energy orbits of high eccentricity, and among these there appear to be two pairs of dynamically associated clusters; (3) the most energetic cluster in our sample, NGC 3201, is on a highly retrograde orbit?which had already been surmised from radial velocity alone?with an apocentric distance of 22 kpc; and (4) none of the metal-poor clusters appear to be associated with the recently detected SDSS streams or with the Monoceros structure. These are the first results of the Southern Proper Motion program where the second-epoch observations are taken with the recent CCD camera system installed on the double astrograph at El Leoncito, Argentina.
TL;DR: A rapid screening method based on ultrafiltration and gel permeation chromatography and a screening through the polymerase chain reaction (PCR) revealed many positive strains, but statistical analysis did not reveal any relationship between the type and origin of the strains, the presence or absence of a capsular polysaccharide or EPS.
TL;DR: In this paper, the combination of small spherical particles in conjunction with nematogenic mesogens and hydrocarbon chains allows for the rational design of materials with nematic phase behaviour, and the usefulness of the approach is demonstrated for two systems, where the particles have been characterised by NMR and TEM and mesomorphic properties have been identified using DSC and OPM.
Abstract: Design rules for the investigation of nanoparticles covered with an organic monolayer are explored. The combination of small “spherical” particles in conjunction with nematogenic mesogens and hydrocarbon chains allows for the rational design of materials with nematic phase behaviour. The usefulness of the approach is demonstrated for two systems, where the particles have been characterised by NMR and TEM and mesomorphic properties have been identified using DSC and OPM.
TL;DR: A thermal lattice Boltzmann model for a van der Waals fluid is proposed and reproduces at second order of a Chapman-Enskog expansion, the theory recently introduced by A. Onuki.
Abstract: A thermal lattice Boltzmann model for a van der Waals fluid is proposed. In the continuum, the model reproduces at second order of a Chapman-Enskog expansion, the theory recently introduced by A. Onuki [Phys. Rev. Lett. 94, 054501 (2005)]. Phase separation has been studied in a system quenched by contact with external walls. Pressure waves favor the thermalization of the system at initial times and the temperature, soon with respect to typical times of phase separation, becomes homogeneous in the bulk. Alternate layers of liquid and vapor form on the walls and disappear at late times.
TL;DR: In this paper, the authors considered singular elliptic problems of the form − Δ u ± p (d (x ) ) g ( u ) = λ f ( x, u ) + μ | ∇ u | a in Ω, where Ω is a smooth bounded domain in R N, d ( x ) = dist ( x, ∂ Ω ), λ > 0, μ ∈ R, 0 a ⩽ 2, and f is a nondecreasing function.
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TL;DR: In this paper, the existence and non-existence results for quasilinear elliptic problems with nonlinear boundary conditions and lack of compactness are established for variational methods with geometrical features.
Abstract: Existence and non-existence results are established for quasilinear elliptic problems with nonlinear boundary conditions and lack of compactness. The proofs combine variational methods with the geometrical feature, due to the competition between the different growths of the non-linearities.
TL;DR: An operational semantics of a basic class of P systems is defined, and two implementations of the operational semantics using rewriting logic are given, including two operational correspondence results.
01 Jan 2007
TL;DR: In this paper, the authors report on some recent results related to various singular phenomena arising in the study of some classes of nonlinear elliptic equations and establish qualitative results on the existence, nonexistence or the uniqueness of solutions.
Abstract: In this survey we report on some recent results related to various singular phenomena arising in the study of some classes of nonlinear elliptic equations. We establish qualitative results on the existence, nonexistence or the uniqueness of solutions and we focus on the following types of problems: (i) blow-up boundary solutions of logistic equations; (ii) Lane—Emden—Fowler equations with singular nonlinearities and subquadratic convection term. We study the combined effects of various terms involved in these problems: sublinear or superlinear nonlinearities, singular nonlinear terms, convection nonlinearities, as well as sign-changing potentials. We also take into account bifurcation nonlinear problems and we establish the precise rate decay of the solution in some concrete situations. Our approach combines standard techniques based on the maximum principle with nonstandard arguments, such as the Karamata regular variation theory.
TL;DR: This review describes the structural features of MMPs, with special emphasis on their interaction with specific inhibitors, and the effect of new, hydroxamatebased inhibitors on MMP isolated from bovine brain is evaluated.
Abstract: MMPs (matrix metalloproteinases) are zinc-dependent endopeptidases that degrade both matrix and non-matrix proteins. They play an important role in morphogenesis, and in a wide range of processes including tissue repair and remodelling. Their abnormal expression contributes to pathological processes including arthritis, cancer, and cardiac and central nervous system diseases, which explains the large interest in finding specific MMP inhibitors for therapeutic use. In this review we describe the structural features of MMPs, with special emphasis on their interaction with specific inhibitors. The effect of new, hydroxamatebased inhibitors on MMP isolated from bovine brain is evaluated.
TL;DR: In this article, a sol-gel method was used to synthesize perovskite LaCoO3 powders from metal nitrates or acetates, and citric acid as the chelating agent at room temperature.
Abstract: LaCoO3-based materials are studied because they exhibit interesting, electrical, magnetic and catalytic properties. In this contribution, LaCoO3 powders were synthesized by sol–gel method in aqueous medium starting from metal nitrates or acetates, and citric acid as the chelating agent at room temperature. The relation between the reactions in solution, crystallization pathway and morphology is discussed. The dried powders were amorphous. Their thermal decomposition occurs stepwise upon heating to 400 °C for nitrate or 500 °C for acetate-based precursors, respectively. Pure perovskite LaCoO3 phase is formed after heating at 600 °C in the case of nitrates while in the case of acetates separation of phases occurs when 2 mol of citric acid are used. The choice of the precursor influences the morphology of the powders heated at 600 °C. The nitrate-based powders are composed of agglomerates of fine particles while the acetate-based powders mainly consist of gel fragments. Some preliminary electrical and catalytic properties are also presented.
TL;DR: In this paper, the effect of thermal and catalytic hydrogenation was improved by using catalysts such as commercial hydrogenation DHC-8 catalyst and metal loaded activated carbon and the upgraded degradation products were separated in three fractions (residue, liquids and gases) and characterized by suitable methods such as gas chromatography (GC-MSD, GC-AED), infrared (FT-IR) and 1 H-NMR spectroscopy, elemental analysis, etc.
TL;DR: In this paper, generalized magnetic Schrodinger operators of the form H h (A, V ) = h ( Π A ) + V, where h is an elliptic symbol, V is a scalar potential, and A is a vector potential defining a variable magnetic field B.