Articles de revues : « Barium ions »

1

Chikina, I., et V. Shikin. « Barium ions in liquid helium ». Low Temperature Physics 44, n^o 5 (mai 2018) : 401–9. http://dx.doi.org/10.1063/1.5034150.

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Kostishin V. G., Korovushkin V. V., Isaev I. M., Salogub D. V., Trukhanov S.V. et Trukhanov A.V. « Crystal chemistry and magnetic properties of BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- hexaferrite upon heterovalent substitution of iron with zirconium ». Physics of the Solid State 64, n^o 2 (2022) : 168. http://dx.doi.org/10.21883/pss.2022.02.52964.225.

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Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Messbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+->Zr4++Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x=0.6) was established. It was noted that additional sextets in the Messbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established. Keywords: M-type barium hexaferrite, heterovalent substitution, limited isomorphism, Messbauer spectroscopy, magnetic properties

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Zezulová, Anežka, Theodor Staněk et Tomáš Opravil. « The Influence of Barium Compounds on the Formation of Portland Cement Clinker ». Materials Science Forum 851 (avril 2016) : 116–21. http://dx.doi.org/10.4028/www.scientific.net/msf.851.116.

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Portland clinker is thanks to its large-scale production a continuously studied topic. Clinker, or Portland cement, is used for construction purposes or for insulation and special applications. One of these special applications could be shielding of different types of radiation by making use of the content of barium ions. The present article examines the influence of barium oxide on the formation and properties of Portland clinker, which could be, by incorporation of barium ions into the system, used as a binder for buildings resistant to various types of radiation. Barium sulphate and barium carbonate were added to the raw meal in order to prepare clinkers with different content of barium oxide. The effect of barium on the formation of clinker phases was studied (by XRD – Rietveld analysis and by the microscopic point counting method), as well as the rate of alite formation under isothermal conditions. Furthermore, the ability of barium to become a part of clinker minerals was studied by SEM with EDS.

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Itoh, Junichi, Hajime Haneda, Shunichi Hishita, Isao Sakaguchi, Naoki Ohashi, Dae-Chul Park et Isamu Yashima. « Diffusion and solubility of holmium ions in barium titanate ceramics ». Journal of Materials Research 19, n^o 12 (1 décembre 2004) : 3512–20. http://dx.doi.org/10.1557/jmr.2004.0466.

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Ho ion solubility and diffusivity were evaluated in barium titanate ceramics in which Ho ions were implanted with an accelerating voltage of 500 keV. The depth profile of the ions was composed of three regions in the post-annealed sample: the first was the precipitation region, the second was a region created by lattice diffusion of Ho ions, and the third was a region created by grain-boundary diffusion. The Ho lattice diffusion characteristics were similar to those of Ni ion diffusion in barium titanate ceramics, and we concluded that the diffusion mechanism was the same as that responsible for Ni ions. The Ho ions diffused through the B-site (Ti-site) and were then exchanged with A-site ions. This mechanism suggests that a small number of Ho ions dissolved in the B-site. Preferential grain-boundary diffusion was also observed. The grain-boundary diffusion coefficients were four to five orders of magnitude larger than the volume diffusion coefficients. The solubility of Ho ions was estimated to be a few thousand parts per million in barium titanate ceramics.

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Kovrlija, Ilijana, Janis Locs et Dagnija Loca. « Incorporation of Barium Ions into Biomaterials : Dangerous Liaison or Potential Revolution ? » Materials 14, n^o 19 (2 octobre 2021) : 5772. http://dx.doi.org/10.3390/ma14195772.

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In the present manuscript, a brief overview on barium, its possible utilization, and the aftermath of its behavior in organisms has been presented. As a bivalent cation, barium has the potential to be used in a myriad of biochemical reactions. A number of studies have exhibited both the unwanted outcome barium displayed and the advantages of barium laden compounds, tested in in vitro and in vivo settings. The plethora of prospective manipulations covered the area of hydrogels and calcium phosphates, with an end goal of examining barium’s future in the tissue engineering. However, majority of data revert to the research conducted in the 20th century, without investigating the mechanisms of action using current state-of-the-art technology. Having this in mind, set of questions that are needed for possible future research arose. Can barium be used as a substitute for other biologically relevant divalent cations? Will the incorporation of barium ions hamper the execution of the essential processes in the organism? Most importantly, can the benefits outweigh the harm?

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Костишин, В. Г., В. В. Коровушкин, И. М. Исаев, Д. В. Салогуб, С. В. Труханов et А. В. Труханов. « Кристаллохимия и магнитные свойства гексаферрита BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- при гетеровалентном замещении железа цирконием ». Физика твердого тела 64, n^o 2 (2022) : 179. http://dx.doi.org/10.21883/ftt.2022.02.51927.225.

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Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Mössbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+ → Zr4+ + Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x = 0.6) was established. It was noted that additional sextets in the Mössbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established.

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Yoon, Dang-Hyok, et Burtrand I. Lee. « Effects of Excess Barium Ions on Aqueous Barium Titanate Tape Properties ». Journal of the American Ceramic Society 87, n^o 6 (juin 2004) : 1066–71. http://dx.doi.org/10.1111/j.1551-2916.2004.01066.x.

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CAI, S., P. H. XIN, P. F. WANG, B. B. ZHANG, Y. B. HAN, X. L. PENG, B. HONG et al. « THE SOL–GEL SYNTHESIS OF RARE-EARTH IONS SUBSTITUTED BARIUM HEXAFERRITES AND MAGNETIC PROPERTIES ». Modern Physics Letters B 27, n^o 26 (10 octobre 2013) : 1350192. http://dx.doi.org/10.1142/s0217984913501923.

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In this paper, a series of rare-earth-doped barium hexaferrite powders ( Ba 0.95 Re 0.05- Fe 12 O 19 and Ba 0.95 Re 0.05 M 0.05 Fe 11.95 O 19: Re = La , Pr , Sm , Nd , Gd , Dy , Yb ; M = Zn 2+, Mn 2+, [Formula: see text]) were synthesized by the sol–gel self-combustion technology. The phase composition and the magnetic properties of the as-prepared barium hexaferrites were characterized and discussed with X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that the barium hexaferrites exhibited the magnetoplumbite phase structure with the average diameter of 45 nm. Magnetic properties study revealed that the variation of the saturation magnetization (Ms) was similar with the change of the rare-earth ions radius, but the change of Ms was low. This indicated that the magnetic moments of rare-earth ions could not affect Ms. The magnetocrystalline anisotropy field mainly influenced the anisotropism of hexaferrites, and the coercivity (Hc) of the rare-earth ions doped barium hexaferrites basically decreased with the increasing orbital quantum numbers (except Sm 3+ and Gd 3+). Further study showed the co-addition of Zn 2+ and Mn 2+ did not change the trend of Ms and Hc. Thus, it is concluded that the rare-earth ions played an important role for the anisotropy field of barium hexaferrites.

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Nazarenko, Alexander Y. « Crystal structure of strontium and barium acesulafame (6-methyl-4-oxo-4H-1,2,3-oxathiazin-3-ide 2,2-dioxide) ». Acta Crystallographica Section E Crystallographic Communications 74, n^o 5 (24 avril 2018) : 698–702. http://dx.doi.org/10.1107/s2056989018006059.

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Both strontium and barium acesulfames, namely poly[aquabis(μ3-6-methyl-2,2-dioxo-1,2λ6,3-oxathiazin-4-olato)strontium(II)], [Sr(C4H4NO4S)2(H2O)]n, and the barium(II) analogue, [Ba(C4H4NO4S)2(H2O)]n, crystallize in nearly identical isotypic forms, with barium–oxygen interatomic distances being longer due to the larger ionic radius of the barium(II) ion. The coordination number of the metal ion is 9; the coordination polyhedra can be described as distorted capped square antiprisms [Johnson solidJ10; Johnson (1966).Can. J. Math.18, 169–200]. The conformation of the acesulafame ions is a distorted envelope with an out-of-plane S atom. Metal and acesulfame ions are assembled into infinitive chains along the [100] axis. These chains are connectedviahydrogen bonds into a three-dimensional network.

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Zaitsev, Sergei Yu, Marina S. Tsarkova et Ilia S. Zaitsev. « Polymeric Composite Materials for the Detection of Barium Ions in Aqueous Solutions ». International Journal of Polymer Science 2019 (3 février 2019) : 1–5. http://dx.doi.org/10.1155/2019/4951327.

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The design of polymeric composite materials (PCM) for the optical control of chemical substances is currently one of the actively developing fields of science “at the junction” of polymer, organic, and analytical chemistry. The purpose of this work is the preparation of PCM containing derivatives of crown ethers for the optical determination of barium ions. The polymeric composite materials containing a novel optical molecular sensor have been obtained and investigated on the basis of a number of film-forming polymers. The best results have been obtained for PCM based on polyvinyl butyral films (since the fluorescence and absorption maxima shifted by 9 and 16 nm, respectively) in the fluorescence and absorption spectra of this PCM in the presence of barium ions. This makes the proposed PCM highly promising as sensor elements for the detection of the barium ions in the aqueous solutions.

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Schnermann, J. « Effects of barium ions on tubuloglomerular feedback ». American Journal of Physiology-Renal Physiology 268, n^o 5 (1 mai 1995) : F960—F966. http://dx.doi.org/10.1152/ajprenal.1995.268.5.f960.

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The furosemide sensitivity of the tubuloglomerular feedback (TGF) response has suggested an important role for the Na-2Cl-K cotransporter in the mechanism by which increased luminal NaCl concentration causes afferent arteriolar vasoconstriction. The present experiments in anesthetized rats were performed to evaluate the effect of K channel blockade with Ba on TGF, since Ba has been shown to inhibit NaCl transport in the thick ascending limb. The presence of either 1.5 or 2 mM BaCl2 during retrograde perfusion with a 135 mM NaCl solution reduced the decrease of early proximal flow rate (VEP) by 2.7 +/- 0.76 (P < 0.02) and 4.2 +/- 0.8 nl/min (P < 0.01) compared with perfusion without BaCl2. Retrograde perfusion with 38 mM NaCl + 5 mM KCl reduced VEP by 10.4 +/- 1.3 nl/min, whereas 40 mM NaCl + 1.5 mM BaCl2 caused a reduction by only 6.1 +/- 1.4 nl/min (P < 0.001). In contrast to the inhibition caused by retrograde perfusion with low concentrations of BaCl2, increased vasoconstriction was seen during retrograde perfusion with 5 mM BaCl2 or during orthograde perfusion with 10 mM BaCl2. The addition of 10(-4) M furosemide to a solution containing 5 mM BaCl2 largely blocked the increased vasoconstrictor response. Peritubular perfusion with a solution containing 5 mM BaCl2 caused a fall in stop-flow pressure in an adjacent nephron by 10.7 +/- 1.5 mmHg (P < 0.001). These results indicate that under our experimental conditions Ba ions exert a dual effect on vascular responses to changes in luminal NaCl concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

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Fallahpour, Reza-Ali, Markus Neuburger et Margareta Zehnder. « Triangular barium macrocyclic complex encapsulating perchlorate ions ». Inorganic Chemistry Communications 1, n^o 3 (mars 1998) : 90–92. http://dx.doi.org/10.1016/s1387-7003(98)00023-9.

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Vaněk, K., et V. Jedináková. « Adsorption of barium ions on α-FeOOH ». Journal of Colloid and Interface Science 111, n^o 1 (mai 1986) : 276–79. http://dx.doi.org/10.1016/0021-9797(86)90027-5.

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Garwan, M. A., L. R. Kilius, A. E. Litherland, M.-J. Nadeau et X.-L. Zhao. « The negative ions of strontium and barium ». Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms 52, n^o 3-4 (décembre 1990) : 512–16. http://dx.doi.org/10.1016/0168-583x(90)90468-a.

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Reyher, H. J., H. Bauer, C. Huber, R. Mayer, A. Schäfer et A. Winnacker. « Spectroscopy of barium ions in He II ». Physics Letters A 115, n^o 5 (avril 1986) : 238–44. http://dx.doi.org/10.1016/0375-9601(86)90474-3.

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Khromushin, Igor V., Taтiana I. Aksenova, Turgora Tuseyev, Karlygash K. Munasbaeva, Yuri V. Ermolaev, Victor N. Ermolaev et Arman S. Seitov. « Modification of Barium Cerate by Heavy Ion Irradiation ». Advanced Materials Research 781-784 (septembre 2013) : 357–61. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.357.

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The effect of irradiation with heavy ions Ne, Ar, and Kr of various energies on the structure and properties of ceramic barium cerate doped with neodymium and annealed in air at 650°C for 7 hours is studied. It is noted that blistering was observed on cerate surface during its irradiation by low energy Ne ions, whereas it was not observed under low-energy Ar and Kr ions irradiation. Irradiation of the cerate with high energy ions caused partial amorphization of the irradiated surface of the material, while the structure of the non-irradiated surface did not change. In addition, the irradiated surface of the cerate endured solid-phase structural changes. Thus, upon high-energy ions irradiation in the range of Ne, Ar, Kr the cerate surface resembled the stages of spherulite formation - nucleation, growth (view of cauliflower), formation of spherulitic crust, respectively. The increase in water molecules release and reduction of molecular oxygen release from the barium cerate, irradiated by high-energy ions is found during vacuum constant rate heating. It is concluded that cerates undergo changes to the distances significantly exceeding the ion ranges in these materials. Features of high-energy ions influence on thermal desorption of carbon dioxide from cerates show, apparently, the formation of weakly bound carbonate compounds on the cerate surface in the irradiation process.

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Eufrasio, Andreza M., Ian Pegg, Amrit Kafle, Winnie Wong-Ng, Qingzhen Huang et Biprodas Dutta. « Metal–Insulator Transition in Doped Barium Plumbates ». Electronic Materials 2, n^o 3 (16 septembre 2021) : 428–44. http://dx.doi.org/10.3390/electronicmat2030029.

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Solid solutions in the Ba(Pb1−xSrx)O3−z system were prepared by aliovalent substitution of Pb4+ by Sr2+ ions to investigate the effect of cation stoichiometry on thermal and electrical properties as x was varied between 0 and 0.4, in the temperature range 300–523 K. The starting compound, barium plumbate (BaPbO3), has a perovskite structure and is known to exhibit metallic conductivity due to an overlap of the O2p nonbonding and the Pb–O spσ antibonding band, which is partially filled by the available electrons. The large difference in the ionic radii between the Pb4+ and Sr2+ ions introduces significant strain into the (Pb/Sr)O6 octahedra of the perovskite structure. Additionally, charged defects are created on account of the different oxidation states of the Pb4+ and Sr2+ ions. Evidence of a metal to insulator transition (MIT) of the Mott–Hubbard type has been observed at a critical concentration of Sr2+ ions.

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Zezulova, A., M. Dzurov et M. T. Palou. « Mechanical properties of chemically bonded phosphate ceramics with incorporation of barium ions ». Journal of Physics : Conference Series 2341, n^o 1 (1 septembre 2022) : 012005. http://dx.doi.org/10.1088/1742-6596/2341/1/012005.

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Abstract Chemically bonded phosphate ceramic is an advanced ceramic material with unique physicochemical properties. The ceramic is formed by an acid-base reaction at ambient temperature. This work is focused on the preparation of this ceramic with barium ions incorporated in the matrix. The shielding of different types of ionization is usually poor in this binder; barium as a heavy element increases material resistance to ionization energy. As part of the development of composites for radiation shielding, the paper describes partial research on the possibility of preparing chemically bonded phosphate ceramic incorporating barium and having good mechanical properties.

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LEI, B., et I. PERLMAN. « The contributions of voltage- and time-dependent potassium conductances to the electroretinogram in rabbits ». Visual Neuroscience 16, n^o 4 (juillet 1999) : 743–54. http://dx.doi.org/10.1017/s0952523899164137.

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The electroretinogram (ERG) is generated by light-induced electrical activity in retinal cells. Since potassium ions and potassium conductances play a major role in determining the membrane potential of cells, changes in these are expected to affect the amplitude and pattern of the ERG. We recorded the ERG responses and the isolated P-III waves of rabbits after intraocular injections of specific blockers for potassium channels. 4-aminopyridine (4-AP) did not cause any noticeable changes in the ERG while tetraethylammonium chloride (TEA) induced time-dependent effects. Short-term (1–2 h) effects were expressed as significant augmentation of the b-wave with little change in the a-wave. At longer periods of follow-up, the a-wave increased in amplitude while the b-wave decreased. TEA augmented the amplitude of the isolated P-III wave. These effects of TEA can be explained by TEA-induced depolarization of the photoreceptors. Cesium ions and barium ions induced substantial augmentation of the b-wave. Barium but not cesium ions reduced the isolated P-III component of the ERG probably by blocking the potassium channels in the Müller cells. The augmentation of the b-wave by both barium or cesium ions is inconsistent with the Müller cells hypothesis for the ERG b-wave.

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White, Samuel, Kunyu Zheng, Jordan Tanen, Joseph E. Lesniewski et Kaveh Jorabchi. « Elemental detection of fluorochemicals by nanospray-induced chemical ionization in afterglow of an inductively coupled plasma ». Journal of Analytical Atomic Spectrometry 37, n^o 4 (2022) : 870–82. http://dx.doi.org/10.1039/d1ja00449b.

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Kelele, Kiflom Gebremedhn, Aschalew Tadesse, Tegene Desalegn, Suresh Ghotekar, Ruthramurthy Balachandran et Hanabe Chowdappa Ananda Murthy. « Synthesis and characterizations of metal ions doped barium strontium titanate (BST) nanomaterials for photocatalytic and electrical applications : A mini review ». International Journal of Materials Research 112, n^o 8 (1 août 2021) : 665–77. http://dx.doi.org/10.1515/ijmr-2020-8149.

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Abstract The ferroelectric barium strontium titanate (Ba1-xSrxTiO3) is a homogeneous solid solution prepared from the mixture of barium titanate (BaTiO3), strontium titanate (SrTiO3) and titanium (IV) isopropoxide. Barium strontium titanate (BST) nanomaterials with improved permittivity and dielectric properties due to their nano-properties have attracted great interest for extensive and versatile applications as super capacitors, dielectrics, ceramics and catalysts. Introduction of metal ion dopants into the parent system of BST significantly alters its structural, morphological, electrical, optical and dielectric characteristics. This review is aimed at addressing synthesis, characterization methods, photocatalytic and electrical applications of metal ions doped BST nanomaterials. The effect of doping BST, through metal ions, on its properties and application with most probable reasons have been thoroughly discussed.

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Shcherbakov, S. V., A. G. Nalogin, V. G. Kostishin, A. A. Alekseev, E. A. Belokon et I. M. Isaev. « Influence of aluminum substitution on the fi eld of effective magnetic anisotropy and the degree of magnetic texture of anisotropic polycrystalline hexagonal ferrites of barium and strontium for substrates of microstrip devices of microwave electronics ». Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 21, n^o 3 (31 octobre 2019) : 166–74. http://dx.doi.org/10.17073/1609-3577-2018-3-166-174.

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Abstract. In this paper, the effect of Al3+ ions substitutions on the value of the effective magnetic anisotropy field НАeff and the degree of magnetic texture f of the anisotropic polycrystalline hexagonal barium and strontium ferrites were studied. The samples were obtained by the ceramic technology method and the texture was formed by pressing in a magnetic field. The sample preparation technology presented in detail. The batches of barium hexaferrites were synthesized with the concentration of Al3+ ions: 0.9; 1.4; 2.5 and 2.6 formula units while strontium hexaferrites had Al3+ concentration of 0.1 formula units. It has been shown that by this technology barium and strontium hexaferrites with high value of (in range of 19—35 kOe) and with f = 80—83% could be obtained. The achieved values of НАeff and f could be sufficient for the production of substrates for microstrip microwave devices in millimeter−wave region.For the first time a raise in the degree of magnetic texture of polycrystalline barium hexaferrites with an increase of concentration of Al3+ ions were detected; a slight (5.5—5.8%) magnetic texture of isotropic strontium hexaferrites was also detected. The achieved results discussed in detail. For studied hexaferrites the mechanism of magnetic texture formation during the process of synthesis is proposed.

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Wang, Jian, et Yi Fan Zhang. « The Study of Divalent Metal Ion Catalysts on Phenol-Formaldehyde Resol Resins ». Applied Mechanics and Materials 71-78 (juillet 2011) : 818–21. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.818.

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The curing characteristic of phenol-formaldehyde resol resins catalyzed with magnesium hydroxide, calcium hydroxide and barium hydroxide was studied in this study.The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by fourier transform infrared.The results indicated that divalent metal ions catalysts played an important role influence both the cure rate and cure time.Phenol formaldehyde resin catalysed by diffierent catalysts showed diffierent addition of formaldehyde onto ortho positions of phenolic rings.The order of the divalent metal ions effectiveness studied in alkaline conditions is calcium hydroxide, barium hydroxide and magnesium hydroxide.

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Solessio, Eduardo, David M. Linn, Ido Perlman et Eric M. Lasater. « Characterization With Barium of Potassium Currents in Turtle Retinal Müller Cells ». Journal of Neurophysiology 83, n^o 1 (1 janvier 2000) : 418–30. http://dx.doi.org/10.1152/jn.2000.83.1.418.

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Müller cells are highly permeable to potassium ions and play a crucial role in maintaining potassium homeostasis in the vertebrate retina. The potassium current found in turtle Müller cells consists of two components: an inwardly rectifying component and a linear, passive component. These currents are insensitive to broadband potassium channel blockers, tetraethylammonium (TEA) and 4-aminopyridine (4-AP) and well blocked by barium. Differential block by the polyamine spermine suggests that these currents flow through different channels. In this study, we used barium ions as a probe to investigate the properties of these currents by whole cell, voltage-clamp recordings from isolated cells. Current-voltage ( I-V) relationships generated from current responses to short (35 ms) and long (3.5 s) voltage pulses were fit with the Hill equation. With extracellular barium, the time course of block and unblock was voltage and concentration dependent and could be fit with single exponential functions and time constants larger than 100 ms. Blocking effects by extracellular barium on the two types of currents were indistinguishable. The decrease of the outward current originates in part due to charge effects. We also found that intracellular barium was an effective blocker of the potassium currents. The relative block of the inward rectifier by intracellular barium suggests the existence of two “apparent” binding sites available for barium within the channel. Under depolarizing conditions favoring the block by internal polyamines, the Hill coefficient for barium binding was 1, indicating a single apparent binding site for barium within the pore of the passive linear conductance. The difference in the steepness of the blocking functions suggests that the potassium currents flow through two different types of channels, an inward rectifier and a linear passive conductance. Last, we consider the use of barium as an intracellular K+ channel blocker for voltage-clamp experiments.

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Tang, Shan Fa, Wei Zou, Yu Juan Xiong, Xue Yang et Lei Tian. « Research on the Scale Inhibition Performance of AA/MA/MAC Copolymer ». Advanced Materials Research 554-556 (juillet 2012) : 223–26. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.223.

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The terpolymer was synthesized by maleic anhydride (MA), acrylic acid (AA) and methyl acrylate (MAC) and the structure was also conformed. Its scale inhibition effect was also studied in high barium and strontium ion concentration aqueous medium and simulated formation water (Ca2+, Mg2+, Ba2+, Si2+) condition. The results indicate that when additive amount of AA/MAC/MA is 60 mg/L, the inhibition rate is up to 100% and 80% for BaSO4 scale and SrSO4 scale respectively, but only 50% for calcium scale. And the scale inhibition rate moderately increases with the dosage increasing. The scale inhibition effect of AA/MAC/MA is also very obvious in simulated formation water containing low calcium ions (400 mg/L) and high barium ions (500 mg/L) as well as strontium ions (500 mg/L). It can satisfy the need of restraining composite scale (BaSO4 scale and SrSO4 scale as well as CaSO4 scale) in high calcium and barium strontium ion aqueous medium when compounded with calcium scale inhibitors CY and CX respectively.

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Zuo, Cheng Gang, An Xian Lu, Li Gang Zhu et Wo Yun Long. « Luminescence of Ce ³⁺ or Tb ^3⁺ in Lithium-Barium-Gadolinium-Aluminosilicate Oxyfluoride Glasses ». Advanced Materials Research 239-242 (mai 2011) : 468–71. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.468.

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Ce3+ or Tb3+ ions activated lithium-barium-gadolinium-aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Ce3+ or Tb3+-doped lithium-barium-gadolinium-aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. Energy transfer process from Gd3+ ion to Ce3+ or Tb3+ ion is indicated.

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Jamari, N. Laili A., J. Frederik Dohmann, Andrea Raab, Eva M. Krupp et Joerg Feldmann. « Novel non-target analysis of fluorine compounds using ICPMS/MS and HPLC-ICPMS/MS ». Journal of Analytical Atomic Spectrometry 32, n^o 5 (2017) : 942–50. http://dx.doi.org/10.1039/c7ja00051k.

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The first study which shows that total fluorine determination and fluorine speciation analysis are possible with a conventional ICPMS/MS by creating BaF⁺ions in the plasma and limiting the polyatomic interfering barium oxide/hydroxide ions at a ppb level.

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Abdelghany, A. M., et Ahmed H. Hammad. « Impact of vanadium ions in barium borate glass ». Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy 137 (février 2015) : 39–44. http://dx.doi.org/10.1016/j.saa.2014.08.012.

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Bettinelli, Marco, Adolfo Speghini, Airán Ródenas, Pablo Molina, Maria de la O. Ramírez, Bárbara Capote, Daniel Jaque, Luisa E. Bausá et José García Solé. « Luminescence of lanthanide ions in strontium barium niobate ». Journal of Luminescence 122-123 (janvier 2007) : 307–10. http://dx.doi.org/10.1016/j.jlumin.2006.01.152.

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Yu, Hsuan-Fu, et Kao-Chao Huang. « Preparation and Characterization of Ester-derived BaFe12O19 Powder ». Journal of Materials Research 17, n^o 1 (janvier 2002) : 199–203. http://dx.doi.org/10.1557/jmr.2002.0029.

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Ultrafine BaFe12O19 powder with crystallite sizes less than 200 nm was prepared via a citric acid precursor method. Citric acid was added into an aqueous solution, containing nitrates of Ba2+ and Fe3+ in a stoichiometric ratio to form barium ferrite, to chelate metallic ions in the solution. The pH of aqueous solutions was adjusted with NH4OH. After ethylene glycol was added into the solution and the system temperature was raised, esterification and dehydratation led to the formation of solid ester precursor. The distribution and contents of metallic ions in the ester are affected by the [citric acid]/[metallic ions] molar ratio used and the pH of starting solutions. When the ester-precursor obtained at pH = 9 with [citric acid]/[metallic ions] = 1.5 was used, crystalline BaFe12O19 appeared at temperatures as low as 923 K, and pure barium ferrite was obtained at 1073 K. According to the experimental results obtained, the reaction mechanism involved in the pyrolysis of esters is proposed and discussed.

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Kamal, Mukarramah M., M. Nor M. Yusuf, N. Atiqah Jailani, S. Sholehah Hussein, R. Hussin, Karim Deraman, W. Nurulhuda W. Shamsuri et Zuhairi Ibrahim. « Luminescence Properties of Europium Ion Doped Barium Borophosphate Phosphor ». Advanced Materials Research 1107 (juin 2015) : 559–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.559.

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A series of BaBPO5phosphors doped with different concentration of Eu2+ions were synthesized by solid state reaction method. The reduction of Eu3+to Eu2+ions were obtained by heating in pure argon atmosphere. The structural properties were analyzed by using X-ray diffraction (XRD). Luminescence properties were measured at room temperature using photoluminescence (PL) spectroscopy and the effects of europium ion in the phosphor were investigated. The XRD results showed that crystal structure of the phosphor is hexagonal single phases. The addition of europium ions exhibit a broad emission band in the violet region peaking at 383 nm corresponding to transition of configuration state 4f65d à 4f7(8S7/2) of Eu2+ions. The emission intensity is affected by the concentration of Eu2+. The optimum intensity is observed for 0.2 mol % of Eu2+ion. The occurrence of emission lines in violet region indicates that this phosphor has potential in solid-state lighting application.

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Stojanovic, B. D., V. R. Mastelaro, Santos Paiva et J. A. Varela. « Structure study of donor doped barium titan ate prepared from citrate solutions ». Science of Sintering 36, n^o 3 (2004) : 179–88. http://dx.doi.org/10.2298/sos0403179s.

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Barium titanates doped with Nb5+, and Y3+, were prepared. The starting powders were synthesized from citrate solutions by the Pechini process and partial Pechini process in two steps. Sintering was performed in the range from 13100 up to 13800C for 2 hours in air atmosphere. The structural study concerning the incorporation of Nb and Y ions in the barium titan ate crystal lattice was performed by XRD, XANES and EXAFS techniques. The dielectric properties were analyzed and the relationship between properties and structure of doped barium titan ate was established.

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Kosarev, N. I. « Two-step photoionization of barium atoms through excited P11,3 levels in optical dense approximation ». Physica Scripta 98, n^o 1 (19 décembre 2022) : 015406. http://dx.doi.org/10.1088/1402-4896/acaa0f.

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Abstract The kinetics of two-step photoionization of barium atoms through excited P 1 1 , 3 levels was studied by numerical simulation method in the optically dense approximation. The first laser at wavelength λ 1 = 553.5 nm ( λ 1 = 791 nm) pumps transition S 0 1 ↔ P 1 1 ( S 0 1 ↔ P 1 3 ). The second laser with λ 2 = 266 nm ( λ 2 = 310 nm) ionizes atoms from the level P 1 1 ( P 1 3 ). The third probe laser with wavelength λ i = 493.41 nm causes resonant fluorescence of barium ions. It is shown that the metastable D 2 3 from the D 1 , 2 , 3 3 triplet in barium is strongly populated through P 1 1 , 3 levels. Therefore, the applying of the ionizing laser tuned to a continuum from this metastable D 2 3 can yield a significant increase in the ionization efficiency. The laser-induced fluorescence method makes it possible to estimate the photoionization yield of barium ions with an error of up to 8%. The loading rate of the barium ion beam into the ion trap, obtained numerically, is consistent with the experimental data [Opt. Exp. 19(17), 16438 (2011)]. The deceleration of ultracold plasma recombination due to the heating of electrons in superelastic collisions for the characteristic times of a two-stage process is predicted.

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Persson, Ingmar, Magnus Sandström et Haruhiko Yokoyama. « Structure of the Solvated Strontium and Barium Ions in Aqueous, Dimethyl Sulfoxide and Pyridine Solution, and Crystal Structure of Strontium and Barium Hydroxide Octahydrate ». Zeitschrift für Naturforschung A 50, n^o 1 (1 janvier 1995) : 21–37. http://dx.doi.org/10.1515/zna-1995-0105.

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Single crystal X-ray data, collected at 298 K, are used to redetermine the crystal structure of the non-isomorphic compounds [Sr(H2O)8](OH)2 and [Ba(H2O)8](OH)2. The eight water oxygen atoms form distorted Archimedean antiprisms around the octahydrated metal ions with mean metal ion-oxygen distances 2.62 and 2.79 Å for strontium and barium, respectively. A second coordination shell of 24 hydrogen-bonded oxygen atoms with mean metal ion-oxygen distances M…OII 4.76 and 4.80 Å, respectively, is observed. The hydroxide ions in both structures have an unusual hydrogen bond arrangement with 5 bonds accepted and one donated.The structure of the solvated strontium and barium ions in aqueous, dimethyl sulfoxide and pyridine solutions has been studied by means of large angle X-ray scattering and extended X-ray absorption fine structure spectroscopy techniques. In aqueous solution independent determinations of the first-sphere metal-oxygen coordination by the two techniques resulted in the bond lengths Sr-O 2.63 (2) and Ba-O 2.81 (3) Å, and for both metal ions a hydration number of 8.1 (3). The second coordination spheres are very diffuse with only about 13 water molecules at similar M…OII distances as in the crystal structures and 2-3 water molecules closer to the metal ions. In dimethyl sulfoxide solution both ions were found to coordinate 6.0 (5) solvent molecules with the distances Sr-O 2.54(1), Sr…S 3.77(1) Å, and Ba-O 2.76(1), Ba…S 3.99(1) Å. For the solvated ions in pyridine solution EXAFS measurements yielded the distances Sr-N 2.57 (2) and Ba-N 2.78 (3) Å, with a probable solvation number of 6.Correlations of hydration enthalpies and partial molar volumes with experimental M-O bond distances in aqueous solution are used to discuss hydration numbers and bond character for all of the alkaline earth metal ions.

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Savenko, V. S., A. V. Savenko et O. S. Pokrovsky. « Solubility of BaSo4 and physicochemical state of barium in seawater ». Океанология 59, n^o 6 (22 décembre 2019) : 939–43. http://dx.doi.org/10.31857/s0030-1574596939-943.

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The solubility of barium sulfate in diluted Na2SO4NaNO3 solutions and seawater with 35 salinity at 22C was experimentally studied. Value of the thermodynamic solubility product of barium sulfate = (7.570.87)1011 was ascertain. It was shown that equilibrium concentration of dissolved barium in seawater is equal 30.7 g/l and water layer of the World Ocean is in the state of low undersaturation for BaSO4. Values of the ionic-mean activity coefficient of BaSO4, total activity coefficient and part of free ions of Ва 2+ in seawater, equal 0.108, 0.131, and 0.59, respectively, were determined according to the experimental data.

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Ikoma, Toshiyuki, Tomohiko Yoshioka, Satoshi Nakamura, Nobutaka Hanagata, Tetsuya Abe, Masataka Sakane, Naoyuki Ochiai et M. Tanaka. « Rigid Hydroxyapatite-Alginate Beads for Sustained Release of Paclitaxel ». Key Engineering Materials 361-363 (novembre 2007) : 535–38. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.535.

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Rigid hydroxyapatite (HAp)-alginate beads were prepared as drug delivery carriers for an anti-cancer drug, paclitaxel (Taxol). Paclitaxel was loaded into the HAp microparticle in process of a spray-drying technique. The HAp-alginate beads including paclitaxel were obtained by a droplet method into barium solution as ionic cross-linkage and dehydration. Cross-sectional analyses indicated the homogeneity of HAp microparticles and barium ions inside the bead. The ratio of alginate to HAp in the beads dominated both mechanical and swelling properties. Drug-release experiment demonstrated the sustained release of paclitaxel from the beads cross-linked with barium ion for 7 days.

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Jindasuwan, Sunisa, Pim Chakornnipit et Sitthisuntorn Supothina. « Influences of Inhibitor and Firing Temperature on Efflorescence Reduction of Clay Products ». Key Engineering Materials 659 (août 2015) : 111–15. http://dx.doi.org/10.4028/www.scientific.net/kem.659.111.

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For ceramic industry, efflorescence is undesirable and cannot be completely eliminated from the finished products. The efflorescence is caused by soluble salts in the raw material and mostly appears as white deposit at the product’s surface. In this research, the removal of sulfate in the raw materials was studied. In addition, the sulfate ions were immobilized by forming a water-insoluble compound. The sulfate ions in the raw materials and fired products were extracted by distilled water, and the concentration was determined by using a UV-visible spectroscopy following the ASTM C1580-09 standard. Three sources of the raw materials from Tambon Suan Phung, Ratchaburi, Tambon Mae Win and Mae Ta, Chiang Mai, were analyzed for sulfate concentrations. The clay from Tambon Suan Phung, Ratchaburi which had the highest sulfate concentration was selected for further study on the effect of inhibitor and firing temperature on efflorescence inhibition. To reduce solubility of the sulfate, three kinds of inhibitor, i.e. barium chloride, barium carbonate and barium hydroxide, were added into the raw material at various concentrations, i.e. 0.5, 1.0, 1.5 and 2.0 wt% and homogeneously mixed by ball milling followed by the addition of distilled water to prepare the clay slip. The clay products were mold casted to 1 x 1 x 3 inch3 in size. Then, they were fired at 800, 900 and 1000 °C. It has been revealed that the addition of barium carbonate at 2 wt%, which is the highest amount employed in this study, and firing temperature of 900 °C resulted in least sulfate leaching due to the formation of water-insoluble barium sulfate. To perform a field test, the fired samples with and without the addition of barium carbonate were immersed in water for 4 months. The efflorescence was observed on the sample without barium carbonate within the 1st month. In contrast, with the addition of barium carbonate, no efflorescence was observed after testing for 4 months.

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Radoczy, T., Kristof Kovacs et N. Sarzo. « Rare Earth Metal Doped Barium Titanates ». Materials Science Forum 589 (juin 2008) : 143–48. http://dx.doi.org/10.4028/www.scientific.net/msf.589.143.

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High purity as well as Ce-, Pr- and Y-doped polycrystalline BaTiO3 ceramics were prepared by wet chemical synthesis. Dielectric constant as well as dielectric loss of dry pressed and sintered ceramics show dielectric constant above 20000 for samples containing 0.5 % Ce accompanied by semiconducting properties. X-ray diffraction studies confirmed Ti being substituted by Ce an Y, while Pr substitutes Ba ions.

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Silva, Margarete S., Guilhermina Ferreira Teixeira, Gustavo F. Cavenago, Lucas L. Silva, Rafael Gomes Dias, Maria Aparecda Zaghete, Mário Cilense, Elson Longo et Alberto A. Cavalheiro. « Effects of the Addition of Ions Barium on the Structural and Electrical Properties of PZT Ceramic ». Materials Science Forum 798-799 (juin 2014) : 199–204. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.199.

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Lead zirconate titanate, with Zr/Ti ratio of 53/47 was prepared by the polymeric precursor method. It was investigated the barium (II) modification at 0.0, 0.2, 0.4 and 0.6 mol% in substitution to the lead (II) cation in A site of perovskite structure. The powder samples were characterized by XRD and the diffraction patterns were used to Rietveld refinement. The percentages of tetragonal and rhombohedral phases and a systematic study of the effect of barium (II) on the morphology and the dielectric properties of PZT were carried out. The results showed that the tetragonal phase is favored and the ceramic density is improved with the barium (II) insertion. The Curie temperature (Tc) is increased besides the slight reduction of dielectric constant (Kc).

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Sorlateap, Sitthisak, et Wirunya Keawwattana. « Preparation and Magnetic Properties of La Substituted Barium Ferrites Synthesized by the Oxide one Pot Synthesis (OOPS) Process ». Advanced Materials Research 634-638 (janvier 2013) : 2250–53. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.2250.

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Lanthanum (La) substituted barium ferrite, Ba1-xLaxFe12O19(x=0.00-0.40) has been synthesized by the oxide one pot synthesis (OOPS) process. The crystalline structure and magnetic properties have been investigated by means of XRD, SEM and VSM. The XRD pattern matched with the barium ferrite structure. The saturation magnetization (Ms) and coercive field (Hc) of ferrites increased by substitution of La ions on Ba sites at the content up to x=0.15 and then decrease.

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Marcus, Maria-Iuliana, Maria Vlad, Gyorgy Deak, Andreea Moncea, Ana-Maria Panait et Gelu Movileanu. « Thermal Stability of Inorganic Pigments Synthesized from Galvanic Sludge ». Revista de Chimie 71, n^o 8 (31 août 2020) : 13–20. http://dx.doi.org/10.37358/rc.20.8.8274.

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Pigments used in ceramic glazes have been obtained by chromium ions extraction from galvanic sludge and their precipitation as barium chromate and lead chromate from technological solutions. The chemical composition was determined by XRF method. Complex thermal analysis TG-DSC, XRD and SEM methods have been used for microstructural characterization and thermal treatment behaviour evaluation, in order to establish the compatibility with the ceramic matrix. XRD spectra have highlighted only lead chromate specific interferences in the monoclinic phase and barium chromate in the orthorhombic phase, suggesting an advanced degree of purity. Weight losses of 2.2% for barium chromate and 3.1% for lead chromate have been recorded on the TG curve at 800�C. As a result of thermal treatment, barium chromate has changed its colour from yellow to green.

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Sergeeva, L. E., et L. I. Bronnikova. « Cell selection with heavy metal ions for obtaining wheat and maize forms tolerant to osmotic stresses ». Faktori eksperimental'noi evolucii organizmiv 22 (9 septembre 2018) : 318–22. http://dx.doi.org/10.7124/feeo.v22.968.

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Aim. The obtaining tolerant to salt and water stresses wheat and maize variants via cell selection with barium and cadmium heavy metal cations were the idea. Barium cations disrupt the cell potassium transport. Cadmium cations affect the dehydrins. The maintenance of these parameters under stress conditions provides the plant tolerance. Methods. Modified media for initial selection were developed by the supplement of the lethal doses of heavy metal ions. Wheat and maize suspension cultures were plated on selective media. The relative fresh biomass growth was the marker of variant stress tolerance. Results. Ba-resistant and Cd‑resistant plant cell lines were obtained. Those variants were tested under salinity and water stress pressure at lethal for wild type cells doses. Cell lines demonstrated the combined tolerance to abiotic stresses. Conclusions. The cell selection with heavy metal ions – is a new approach for isolation cell variants with higher levels of osmotic stresses tolerance. Keywords: cereals, osmotic stresses, cell selection with heavy metal ions, combined tolerance.

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Коровушкин, В. В., А. В. Труханов, В. Г. Костишин, И. М. Исаев, И. В. Щетинин, Н. М. Дуров, А. Ю. Миронович, И. О. Минкова et К. А. Астапович. « Исследование особенностей состава, магнитной и кристаллической структуры гексаферрита бария BaFe-=SUB=-12-x-=/SUB=-Ti-=SUB=-x-=/SUB=-O-=SUB=-19-=/SUB=- ». Физика твердого тела 62, n^o 5 (2020) : 789. http://dx.doi.org/10.21883/ftt.2020.05.49250.622.

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The results of studies of the composition, crystal, and magnetic structure of Ti-substituted barium hexaferrite BaFe12 - xTixO19 (0.25<x<1.5) by Mössbauer spectroscopy, vibration magnetometry, X-ray diffraction, and synchronous thermal analysis are presented. Partial substitution of Fe3 + ions by Ti4 + ions revealed the presence of a limited heterovalent isomorphism realized according to the 2Fe3+ = Ti4+ + Fe2+ while maintaining charge balance. Using Mössbauer spectroscopy, an increase in the electron density of 3d electrons and the presence of Fe2+ in BaFe12 - xTixO19 samples with x = 1.5 were established. The limit of heterovalent isomorphic substitution is established, which is in the range 0.75 <x <1.0. Using Mössbauer spectroscopy and X-ray diffraction, the formation of titanium-containing phases at x = 1, 0, the content of which increases with increasing degree of substitution, is shown. Information is provided on the predominant distribution of substituent ions (Ti4+) in the structure of barium hexaferrite at positions 12k and 2b.

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Fisher, T. E., S. Levy et L. K. Kaczmarek. « Transient changes in intracellular calcium associated with a prolonged increase in excitability in neurons of Aplysia californica ». Journal of Neurophysiology 71, n^o 3 (1 mars 1994) : 1254–57. http://dx.doi.org/10.1152/jn.1994.71.3.1254.

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1. Transient stimulation of an afferent input to the bag cell neurons of Aplysia californica triggers a 30-min period of spontaneous firing termed the afterdischarge. Measurement of free calcium ion concentrations using calcium-sensitive electrodes revealed a biphasic pattern of elevation of intracellular calcium levels during the afterdischarge. Basal calcium levels at the soma were found to rise rapidly during afferent stimulation and then to decline before the onset of spontaneous firing. This early peak in intracellular calcium was followed by a slower, transient elevation of calcium levels during the period of rapid firing that occurs in the first few minutes of afterdischarge. Stimulation of clusters of bag cell neurons in a calcium-free external medium failed to trigger afterdischarge and produced no changes in basal intracellular calcium levels. 2. When calcium ions in the external medium were replaced by barium ions, stimulation of clusters of bag cell neurons triggered afterdischarges that were characterized by long-duration action potentials. Intracellular calcium levels during these afterdischarges rose slowly over the first few minutes of spontaneous firing. Because calcium-sensitive microelectrodes do not respond to barium ions, these data suggest that stimulation of afterdischarge triggers calcium release from an intracellular compartment. 3. During afterdischarges in barium-containing external media, each broadened action potential produced a discrete transient elevation of intracellular calcium levels. A similar effect was observed in isolated bag cell neurons in primary culture when action potentials were stimulated by depolarizing current pulses in a barium-containing medium. These data suggest that, under these conditions, individual action potentials trigger the release of intracellular calcium from some intracellular pool.

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Zhang, Xiaohang, et Marcel Drabbels. « Communication : Barium ions and helium nanodroplets : Solvation and desolvation ». Journal of Chemical Physics 137, n^o 5 (7 août 2012) : 051102. http://dx.doi.org/10.1063/1.4743900.

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Matthias, E. « Multiphoton-induced desorption of positive ions from barium fluoride ». Journal of Vacuum Science & ; Technology B : Microelectronics and Nanometer Structures 5, n^o 5 (septembre 1987) : 1415. http://dx.doi.org/10.1116/1.583627.

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Chen, Guoxong, et Tsu-Jye A. Nee. « Depolarization of near-resonance Rayleigh scattering by barium ions ». Journal of the Optical Society of America B 4, n^o 8 (1 août 1987) : 1303. http://dx.doi.org/10.1364/josab.4.001303.

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Dharmaprakash, S. M., et P. Mohan Rao. « Diffusion coefficient of barium ions from Liesegang ring formation ». Journal of Materials Science Letters 8, n^o 2 (février 1989) : 141–43. http://dx.doi.org/10.1007/bf00730705.

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De la Rosa-Cruz, E., G. A. Kumar, L. A. Diaz-Torres, A. Martı́nez et O. Barbosa-Garcı́a. « Spectroscopic characterization of Nd3+ ions in barium fluoroborophosphate glasses ». Optical Materials 18, n^o 3 (décembre 2001) : 321–29. http://dx.doi.org/10.1016/s0925-3467(01)00171-9.

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Varatharajan, R., P. Jayavel, J. Kumar, R. Jayavel et K. Asokan. « Effects of energetic ions on barium strontium titanate crystals ». Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms 170, n^o 1-2 (septembre 2000) : 145–48. http://dx.doi.org/10.1016/s0168-583x(00)00166-x.

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