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Multinuclear magnetic resonance study of the structure and dynamics of lanthanide(III) complexes of the bis(propylamide) of diethylenetriaminepentaacetic acid in aqueous solution

Geraldes, Carlos F. G. C.; Urbano, Ana M.; Hoefnagel, Mattheus A.; Peters, Joop A.
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
ENG
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The structure and dynamics of the lanthanide(II1) complexes of the bis(propy1amide) of diethylenetriaminepentaacetate (DTPA-PA3 in aqueous solution have been investigated by I3C and I7O NMR. With the use of the longitudinal 13C relaxation times of the NdlI1 complex it is shown that the organic ligand is bound to the lanthanide(II1) ion in an octadentate fashion via the three nitrogens of the diethylenetriamine backbone, the three carboxylate groups, and the two amide oxygens. I7O NMR measurements show that the coordination sphere is completed by one water ligand. The inversion of the lanthanide-bound nitrogens is precluded, and therefore four diastereomeric pairs of isomers are possible for these complexes. Low-temperature I3C NMR spectra show that all these isomers occur in solution. Three dynamic processes have been identified by means of variable-temperature NMR measurements: (i) rapid rotations of the carboxylate groups, (ii) racemization at the middle N atom via interconversions between the two possible conformations of the ethylene bridges, and (iii) racemization at the terminal N atoms of the diethylenetriamine backbone via decoordination-inversion-cmrdination. The barriers of the interconversions between the enantiomers have been determined by line-shape analysis and from coalescence temperatures. A comparison is made with the LnlI1 diethylenetriaminepentaacetate (DTPA) complexes.; http://dx.doi.org/10.1021/ic00063a037

Selective corrosion of 550 degrees C aged Cu10Ni-3Al-1.3Fe alloy in NaCl aqueous solution

LIBERTO, Rodrigo Cesar Nascimento; MAGNABOSCO, Rodrigo; ALONSO-FALLEIROS, Neusa
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
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This work studied the electrochemical behavior of a solution treated or 550 degrees C aged Cu10Ni-3Al-1.3Fe alloy, in 0.01 M NaCl aqueous solution, through potentiodynamic polarization in both stagnant condition or under erosion process. Results showed the occurrence of a passivity break potential (E(pb)), related to the beginning of the denickelification process, which occurred as a localized attack under stagnant electrolyte. Under erosion conditions localized denickelification was not observed, despite of the presence of E(pb). This could indicate that selective corrosion of Ni, which caused the observed E(pb), occurred as a dissolution-redeposition process, with removal of the Cu deposits during erosion process. (C) 2011 Elsevier Ltd. All rights reserved.

Bioremediation of Herbicide Velpar K (R) In Vitro in Aqueous Solution with Application of EM-4 (Effective Microorganisms)

Ramos, Marcio Antonio Gomes; Yoshioka, Sergio Akinobu
Fonte: INST TECNOLOGIA PARANA; CURITIBA-PARANA Publicador: INST TECNOLOGIA PARANA; CURITIBA-PARANA
Tipo: Artigo de Revista Científica
ENG
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This work assessed the bioremediation of herbicide Velpar K (R), in vitro in aqueous solution, used against weeds in sugar cane in Sao Paulo state. The herbicide contained Hexazinone and Diuron. It was used the microbial inoculant denominated Effective Microorganisms (EM-4), pool of microorganisms from soil that contained lactic and photosynthetic bacteria, fungi, yeasts and actinomycetes for bioremediation. Results for the depth of cultivation on agar-agar inoculated with EM-4 showed the microorganisms growth in the concentrations between 0.2% and 1.0% of the Velpar K (R) in the gel. The analysis of high performance liquid chromatography ( HPLC) showed that the EM-4 was effective for the bioremediation of the herbicide, which reached the values of 80% for diuron and 70% for hexazinone after 21 days in solution of 2:1 of Velpar K (R)/EM-4 ratio. These results could be useful for planning the bioremediation of contaminated areas with Velpar K (R).

Bioremediation of herbicide velpar K® in vitro in aqueous solution with application of EM-4 (effective microorganisms)

Ramos, Márcio Antônio Gomes; Yoshioka, Sergio Akinobu
Fonte: Brazilian Archives of Biology and Technology Publicador: Brazilian Archives of Biology and Technology
Tipo: Artigo de Revista Científica
ENG
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This work assessed the bioremediation of herbicide Velpar K®, in vitro in aqueous solution, used against weeds in sugar cane in São Paulo state. The herbicide contained Hexazinone and Diuron. It was used the microbial inoculant denominated Effective Microorganisms (EM-4), pool of microorganisms from soil that contained lactic and photosynthetic bacteria, fungi, yeasts and actinomycetes for bioremediation. Results for the depth of cultivation on agar-agar inoculated with EM-4 showed the microorganisms growth in the concentrations between 0.2% and 1.0% of the Velpar K®in the gel. The analysis of high performance liquid chromatography (HPLC) showed that the EM-4 was effective for the bioremediation of the herbicide, which reached the values of 80% for diuron and 70% for hexazinone after 21 days in solution of 2:1 of Velpar K®/EM-4 ratio. These results could be useful for planning the bioremediation of contaminated areas with Velpar K®.

Estudos sobre a adsorção do corante reativo preto 5 de solução aquosa  usando zeólita de  cinzas de carvão; Studies on the adsorption of reactive black 5 dye of aqueous solution using zeolite of the coal ashes

Ferreira, Patricia Cunico
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/04/2011 PT
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Nesta dissertação foi estudada a zeólita sintetizada a partir de cinzas leves de carvão como um potencial adsorvente para a remoção de corante reativo preto 5 (RP5). Ensaios cinéticos e de equilíbrio foram realizados visando obter-se as melhores condições para a adsorção deste corante, e verificou-se a influência dos seguintes parâmetros: efeito do tempo de contato, concentração inicial do corante, dose do adsorvente, pH da solução aquosa, adição dos sais NaCl e Na2SO4 e temperatura. O tempo de equilíbrio foi alcançado após 420 min. Os dados de adsorção foram ajustados melhor ao modelo cinético de pseudo-segunda-ordem. Para o sistema corante/adsorvente foi aplicado o modelo de isoterma de adsorção de Langmuir, apresentando capacidade de adsorção máxima de 0,685 mg g-1. Os dados experimentais mostraram uma alta porcentagem de remoção de 47,7 a 88,1% de RP5 sobre a zeólita. A alta porcentagem indicou que o material zeolítico apresenta potencial para ser usado como adsorvente na remoção de corantes azo reativo de indústrias têxteis. Os parâmetros termodinâmicos foram avaliados e demonstraram que o processo de adsorção do RP5 sobre a zeólita é espontâneo e exotérmico. Os experimentos adicionando os sais foram realizados para uma melhor simulação das condições reais do efluente. Os resultados mostraram que o equilíbrio de adsorção do RP5 sobre a zeólita na presença de sais foram alcançados em um tempo menor e que quanto maior a concentração dos sais na solução...

Aggregation behavior of hydrophobically modified dextran in aqueous solution: a fluorescence probe study

Vieira, NAB; Moscardini, M. S.; Tiera, VAD; Tiera, M. J.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 137-143
ENG
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Dextrans (M-W = 11.000 and M-w = 40.000) have been modified with 4-hexyl benzoyl chloride and their aggregation behavior was studied in aqueous solution employing the fluorescent probes pyrene and 1,8 anilinonaphtalene sulfonic acid sodium salt (1,8 ANS). The photophysical studies showed that above a critical concentration the derivatives tend to form aggregates having different properties, which depend on both the degree of substitution (alpha) and the molecular weight of the sample. The parameter alpha has a marked effect on the critical aggregation concentrations (CAC) and aggregate proper-ties. Hydrophobic microenvironments can be detected for substituted dextrans having alpha values varying from 0.01 to 0.19. CAC values decreased by two orders and magnitude when the molecular weight increased from 11 to 40 kDa, leading to formation of more apolar aggregates and diminishing by about 30% the polarity of the microenviromnents. Pre-aggregation was evidenced by pyrene excimer emission and intermolecular interactions were responsible by the formation of aggregates leading to solution behaviour similar to that of common surfactants. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

The Hydration of the Neurotransmitter Acetylcholine in Aqueous Solution

Hulme, E. C.; Soper, A. K.; McLain, S. E.; Finney, J. L.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
EN
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Neutron diffraction augmented with hydrogen isotope substitution has been used to examine the water structure around the acetylcholine molecular ion in aqueous solution. It is shown that the nearest-neighbor water molecules in the region around the trimethylammonium headgroup are located either in a ring around the central nitrogen atom or between the carbon atoms, forming a sheath around the onium group. Moreover the water molecules in this cavity do not bond to the onium group but rather form hydrogen bonds with water molecules in the surrounding aqueous environment. Given that in the bound state the onium headgroup must be completely desolvated, the absence of bonding between the onium headgroup and the surrounding water solvent may be selectively favorable to acetylcholine-binding in the receptor site. Away from the headgroup, pronounced hydrogen-bonding of water to the carbonyl oxygen is observed, but not to the ether oxygen in the acetylcholine chain.

Efficacy of nano-hydroxyapatite prepared by an aqueous solution combustion technique in healing bone defects of goat

Nandi, Samit Kumar; Kundu, Biswanath; Ghosh, Samir Kumar; De, Dipak Kumar; Basu, Debabrata
Fonte: The Korean Society of Veterinary Science Publicador: The Korean Society of Veterinary Science
Tipo: Artigo de Revista Científica
EN
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The present study was undertaken to evaluate porous hydroxyapatite (HAp), the powder of which was prepared by a novel aqueous solution combustion technique, as a bone substitute in healing bone defects in vivo, as assessed by radiologic and histopathologic methods, oxytetracycline labeling, and angiogenic features in Bengal goat. Bone defects were created in the diaphysis of the radius and either not filled (group I) or filled with a HAp strut (group II). The radiologic study in group II showed the presence of unabsorbed implants which acted as a scaffold for new bone growth across the defect, and the quality of healing of the bone defect was almost indistinguishable from the control group, in which the defect was more or less similar, although the newly formed bony tissue was more organized when HAp was used. Histologic methods showed complete normal ossification with development of Haversian canals and well-defined osteoblasts at the periphery in group II, whereas the control group had moderate fibro-collagenization and an adequate amount of marrow material, fat cells, and blood vessels. An oxytetracycline labeling study showed moderate activity of new bone formation with crossing-over of new bone trabeculae along with the presence of resorption cavities in group II...

Redox Potential and C-H Bond Cleaving Properties of a Nonheme FeIV=O Complex in Aqueous Solution

Wang, Dong; Zhang, Mo; Bühlmann, Philippe; Que, Lawrence
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 09/06/2010 EN
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High-valent iron-oxo intermediates have been identified as the key oxidants in the catalytic cycles of many nonheme enzymes. Among the large number of synthetic FeIV=O complexes characterized to date, [FeIV(O)(N4Py)]2+ (1) exhibits the unique combination of thermodynamic stability, allowing its structural characterization by X-ray crystallography, and oxidative reactivity sufficient to cleave C-H bonds as strong as those in cyclohexane (DC-H = 99.3 kcal mol-1). However, its redox properties are not yet well understood. In this work, the effect of protons on the redox properties of 1 has been investigated electrochemically in nonaqueous and aqueous solutions. While the cyclic voltammetry of 1 in CH3CN is complicated by coupling of several chemical and redox processes, the FeIV/III couple is reversible in aqueous solution with E1/2 = +0.41 V vs. SCE at pH 4 and involves the transfer of one electron and one proton to give the FeIII-OH species. This is in fact the first example of reversible electrochemistry to be observed for this family of nonheme oxoiron(IV) complexes. C-H bond oxidations by 1 have been studied in H2O and found to have reactions rates that depend on the C-H bond strength but not on the solvent. Furthermore, our electrochemical results have allowed a DO-H value of 78(2) kcal mol-1 to be calculated for the FeIII-OH unit derived from 1. Interestingly...

Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution

Stevenson, Amadeus PZ; Blanco Bea, Duani; Civit, Sergi; Antoranz Contera, Sonia; Iglesias Cerveto, Alberto; Trigueros, Sonia
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 22/02/2012 EN
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Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies.

Microscopic mechanism of protein cryopreservation in an aqueous solution with trehalose

Corradini, Dario; Strekalova, Elena G.; Stanley, H. Eugene; Gallo, Paola
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 06/02/2013 EN
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In order to investigate the cryoprotective mechanism of trehalose on proteins, we use molecular dynamics computer simulations to study the microscopic dynamics of water upon cooling in an aqueous solution of lysozyme and trehalose. We find that the presence of trehalose causes global retardation of the dynamics of water. Comparing aqueous solutions of lysozyme with/without trehalose, we observe that the dynamics of water in the hydration layers close to the protein is dramatically slower when trehalose is present in the system. We also analyze the structure of water and trehalose around the lysozyme and find that the trehalose molecules form a cage surrounding the protein that contains very slow water molecules. We conclude that the transient cage of trehalose molecules that entraps and slows the water molecules prevents the crystallisation of protein hydration water upon cooling.

A New Structural Technique for Examining Ion-Neutral Association in Aqueous Solution

Mason, Philip E.; Neilson, George W.; Price, David L.; Saboungi, Marie-Louise; Brady, John W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
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The method of intramolecular coordination number concentration invariance (ICNCI) is used on neutron diffraction with isotopic substitution (NDIS) measurements of aqueous solutions to separate the intra- and intermolecular contributions to the total intensities. Molecular dynamics simulations of corresponding systems are then used to interpret the ICNCI function. It is found that the ICNCI function (characterized by two concentration measurements) is sensitive specifically to intermolecular association and that the molecular dynamics can successfully replicate this function in the cases of the neutral species xylose and pyridine in aqueous solution. ICNCI functions can also be obtained by the addition of a cosolute (such as adding GdmCl or Gdm2SO4 to pyridine solutions). In that case it is found that molecular dynamics can replicate the ICNCI function for the addition of GdmCl to pyridine, but fails to successfully replicate the same function for the addition of Gdm2SO4. This result implies that the interaction of pyridine with guanidinium sulfate is over-estimated in MD these simulations, and is of significant importance to the use of molecular dynamics simulations to elucidate an atomic level understanding of the Hofmeister series.

Simultaneous Adsorption and Degradation of Cr(VI) and Cd(II) Ions from Aqueous Solution by Silica-Coated Fe0 Nanoparticles

Li, Yongchao; Ma, Hongpu; Ren, Bozhi; Li, Tielong
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
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Core-shell silica-coated Fe0 nanoparticles (Fe@SiO2) were prepared in one-step synthesis by aqueous reduction combined with modified Stöber method. The as-prepared Fe@SiO2 were then used for simultaneous removal of Cr(VI) and Cd(II) from aqueous solution. Batch tests indicated that Fe@SiO2 exhibited high removal capacity toward Cr(VI) and Cd(II). Cr(VI) was removed by Fe@SiO2 through reduction rather than adsorption, while Cd(II) removal was mainly through adsorption. The removal rate increased with increasing initial Fe NPs dose and decreased with increasing initial Cr(VI) and Cd(II) concentrations. Cd(II) adsorption was also strengthened by Cr(VI) reduction with the release of OH−. The removals of Cr(VI) and Cd(II) were weakened in the presence of cations or humic acid, as a result of aggregation and less active site of Fe@SiO2. Overall, the simply prepared Fe@SiO2 were potential material for the heavy metals removed from water.

Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

Itoh, Susumu; Sonoike, Shotaro; Kitamura, Masanori; Aoki, Shin
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 29/01/2014 EN
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Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn2+ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.

Aqueous solution synthesis of reduced graphene oxide-germanium nanoparticles and their electrical property testing

Yin, Huabin; Luo, Jinmei; Yang, Peihui; Yin, Pinghe
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 17/10/2013 EN
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Aqueous solution synthesis of reduced graphene oxide-germanium nanoparticles (RGO-GeNPs) was developed using graphene oxide (GO) as stabilizer, which could be conducive to obtain better excellent electrical properties. The information about morphology and chemical composition of the nanomaterials were obtained by TEM, FTIR, EDS, and XRD measurements. Stable aqueous dispersibility of RGO-GeNPs was further improved by poly(sodium 4-styrenesulfonate) (PSS) to obtain amphiphilic polymer-coated RGO-GeNPs (PSS-RGO-GeNPs). A possible mechanism to interpret the formation of RGO-GeNPs was proposed. The as-synthesized RGO-GeNPs showed excellent battery performance when used as an anode material for Li ion batteries. The resulting nanocomposites exhibited high specific capacity and good cycling stability after 80 cycles. This study showed a facile strategy to synthetize graphene and Ge nanocomposites which can be a hopeful anode material with excellent electrical properties for lithium ion batteries.

Biosorption of cadmium and lead from aqueous solution by fresh water alga Anabaena sphaerica biomass

Abdel -Aty, Azza M.; Ammar, Nabila S.; Abdel Ghafar, Hany H.; Ali, Rizka K.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
EN
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The present work represents the biosorption of Cd(II) and Pb(II) from aqueous solution onto the biomass of the blue green alga Anabaena sphaerica as a function of pH, biosorbent dosage, contact time, and initial metal ion concentrations. Freundlich, Langmuir, and Dubinin–Radushkevich (D–R) models were applied to describe the biosorption isotherm of both metals by A. sphaerica biomass. The biosorption isotherms studies indicated that the biosorption of Cd(II) and Pb(II) follows the Langmuir and Freundlish models. The maximum biosorption capacities (qmax) were 111.1 and 121.95 mg/g, respectively, at the optimum conditions for each metal. From the D–R isotherm model, the mean free energy was calculated to be 11.7 and 14.3 kJ/mol indicating that the biosorption mechanism of Cd(II) and Pb(II) by A. sphaerica was chemisorption. The FTIR analysis for surface function group of algal biomass revealed the existence of amino, carboxyl, hydroxyl, and carbonyl groups, which are responsible for the biosorption of Cd(II) and Pb(II). The results suggested that the biomass of A. sphaerica is an extremely efficient biosorbent for the removal of Cd(II) and Pb(II) from aqueous solutions.

Self-association of unconjugated bilirubin-IX alpha in aqueous solution at pH 10.0 and physical-chemical interactions with bile salt monomers and micelles.

Carey, M C; Koretsky, A P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/06/1979 EN
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Spectrophotometric measurements of bilirubin-IX alpha in water and in aqueous/organic solvent mixtures at pH 10.0 as a function of bilirubin-IX alpha concentration (approx. 0.6--400 microM) are consistent with the formation of dimers (KD - 1.5 microM) in dilute (less than 10 microM) aqueous solution and further self-aggregation to multimers at higher concentrations. Added urea (to 10M) and increases in temperature (to 62 degrees C) obliterate the dimer-multimer transition at 10 microM, but added NaCl (to 0.30 M) promotes strong aggregation of dimers over a narrow concentration range, suggesting a 'micellization' phenomenon. Concentrations of dioxan or ethanol greater than 60% (v/v) in water were required to obtain the absorption spectrum of bilirubin-IX alpha monomers, suggesting that both hydrophobic and electrostatic (pi-orbital) interactions are involved in stabilizing the dimeric state in water. Micellar concentrations of sodium dodecyl sulphate induced spectrophotometric shifts in the dimer absorption spectrum of bilirubin-IX alpha consistent with progressive partitioning of bilirubin-IX alpha monomers into a relatively non-polar region of the micelles and allowed a deduction of the apparent critical micellar concentration that closely approximated the literature values. The pattern of bilirubin IX alpha association with bile salts is complex...

The study of influence of the Teslar technology on aqueous solution of some biomolecules

Andreev, E.; Dovbeshko, G.; Krasnoholovets, V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/04/2012
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The possibility of recording physical changes in aqueos solutions caused by a unique field generated by the Teslar chip (TC) inside a quartz wristwatch has been studied using holographic interferometry. We show that the refraction index of degassed pure distilled water and aqueous solutions of L-tyrosine and b-alanine affected by the TC does not change during the first 10 minutes of influence. In contrast, a 1% aqueous solution of plasma extracted from the blood of a patient with heart-vascular disease changes the refractive index when affected by the TC. The characteristic time of reaction is about 100 s. Based on our prior research experience we state that the response of the system studied to the TC's field is similar to that stipulated by the action of a constant magnetic field with the intensity of 1.1 x 10^{-3} T. Nevertheless, our team could unambiguously prove that the TC generates the inerton field, which is associated with a substructure of the matter waves (and, therefore, it does not relate to the electromagnetic nature).; Comment: 12 pages, 4 Figures, 16 Refs

Integral equation theory for the electrode-electrolyte interface with the central force water model. Results for an aqueous solution of sodium chloride

Vossen, M.; Forstmann, F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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The structure of an aqueous solution of sodium chloride at a planar electrode is investigated by integral equation techniques. With the central force water model the aqueous electrolyte is modelled as a mixture of sodium and chloride ions and partially charged hydrogen and oxygen atoms interacting via effective spherically symmetric pair potentials. The bulk correlation functions are obtained from the Ornstein-Zernike equation. With the Wertheim-Lovett-Mou-Buff equation we have calculated the density profiles at the uncharged and charged electrode. Steric interactions between the differently sized ions and the ice-like water structure near the electrode dominates the ionic distribution. This model electrolyte also responds differently to opposite charges on the electrode.; Comment: Submitted to the Journal of Chemical Physics, REVTeX, 34 pages, 9 figures

Obtaining and characterization of ZnSe nanoparticles from aqueous colloidal dispersions

Hernández,R.; Rosendo,E.; García,G.; Pacio,M.; Díaz,T.; Juárez,H.; Galeazzi,R.; Romano-Trujillo,R.; Nieto,G.
Fonte: Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. Publicador: Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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Structural, morphological and compositional characterizations of zinc selenide (ZnSe) nanoparticles (NPs) are presented. ZnSe NPs have been obtained by colloidal synthesis in aqueous solution using zinc nitrate (Zn(NO3)2) and elemental selenium (Se) as precursors, sodium borohydride (NaBH4) as reducing agent, a solution of sodium hydroxide (NaOH) and pentasodium tripolyphosphate (Na5P3O10) named Extran was used as surfactant. The pH was varied from 8 to 11 and the Zn:Se molar concentration was varied from 3:1 to 1:3. A cleaning process was applied to eliminate the by-products using hydrochloric acid (HCl). ZnSe NPs exhibit a cubic zinc-blende structure. The NPs size was estimated between 4.9 nm and 3.0 nm and depends on molar concentration.