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Articoli di riviste sul tema "Selenites"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 5 marzo 2023

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1

Eisenberg, Sylvan. "Relative Stability of Selenites and Selenates in Feed Premixes as a Function of Water Activity". Journal of AOAC INTERNATIONAL 90, n. 2 (1 marzo 2007): 349–53. http://dx.doi.org/10.1093/jaoac/90.2.349.

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Abstract Sodium selenite is more hygroscopic than sodium selenate. It is, therefore, more likely to dissolve when dispersed in feeds of relatively high water activity. When dissolved, it may form selenious acid and disperse as a vapor. This is easily demonstrated by mounting a filter paper wetted with a reagent such as ascorbic acid over the subject feed, but not in contact with it. The paper turns brown as elemental selenium is formed from reduction of the vapor. Analysis of the paper ensures that the brown is indeed selenium. Though premixes are generally low enough in moisture content to ensure stability of the selenites, this is not true of many feeds. The water activities of a number of feeds, feed premixes, and feed ingredients have been determined instrumentally and compared to those of saturated solutions of sodium selenite and sodium selenate. There is no question that the selenite often dissolves with the potential to react and, in so doing, loses its nutritional function.
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2

Frost, Ray L., B. Jagannadha Reddy e Marilla J. Dickfos. "An Application of near Infrared and Mid-Infrared Spectroscopy to the Study of Uranyl Selenite Minerals: Derriksite, Demesmaekerite, Guilleminite and Haynesite". Journal of Near Infrared Spectroscopy 16, n. 5 (1 gennaio 2008): 455–69. http://dx.doi.org/10.1255/jnirs.813.

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The near infrared (NIR) spectra of the natural uranyl selenite minerals that include derriksite, demesmaekerite, guilleminite and haynesite are examined as a potential indicator of uranium occurring geologic materials at the earth's surface. NIR analysis, complimented with mid-IR studies, was used to investigate the co-ordination of UO22+ and Cu2+ in the uranyl selenites. Bands obtained from the infrared spectra of selenites are interpreted in terms of the stretching vibrations of uranyl, selenite units and OH groups and bending modes. NIR spectra of the uranyl selenite minerals exhibit distinctive characteristics of uranyl ion (UO2)2+ absorptions over the range of 11,500–8000 cm−1. The high- range NIR spectrum of Cu-bearing uranyl derriksite is resolved into two bands, UO22+ 8070 cm−1 and Cu2+ 7175 cm−1. The effect of lead in demesmaekerite leads to distortion of the spectrum and the NIR bands are observed for uranyl ion at 11,305 cm−1 and 8475 cm−1 and for Cu2+ at 7430 cm−1. The δ U–OH bending vibrations are characterised by a strong absorption feature centred at 1015 cm−1 in haynesite. A significant shift for UOH bending vibrations and the absence of ν1 and ν3 vibrations of UO22+ at the expense of Cu2+ are reflected in the spectrum of derriksite. The complexity of bands with shifts to low wavenumbers could take place due to the additional cations of Pb and Cu in the structure of demesmaekerite. NIR spectroscopy has proven to be a most useful tool for the identification of and distinction between different uranyl selenite minerals.
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Gospodinov, G. G., e M. G. Stancheva. "Formation and thermal stability of selenites and hydrogen selenites of samarium". Journal of Thermal Analysis and Calorimetry 78, n. 3 (gennaio 2004): 1057–63. http://dx.doi.org/10.1007/s10973-005-0470-0.

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4

Mička, Zdeněk, e Miroslav Ebert. "The change in the standard Gibbs energy during the formation of the acid selenites of the alkali metals". Collection of Czechoslovak Chemical Communications 51, n. 9 (1986): 1933–41. http://dx.doi.org/10.1135/cccc19861933.

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The heterogeneous M2SeO3-H2SeO3-H2O systems (M = Li, Na, K, Rb, Cs) were studied at 298 K using the Filippov eutonic method, yielding the values of the change in the standard Gibbs energy of reactions leading to the formation of the acid selenites of these metals. It follows from the ΔG0 values that the stability of hydrogenselenites and trihydrogenbis(selenites) increases from lithium to cesium and also, except for cesium salts, on transition from MHSeO3 to MH3(SeO3)2.
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5

Kovrugin, Vadim M., Marie Colmont, Oleg I. Siidra, Dmitry O. Charkin, Almaz Aliev, Sergey V. Krivovichev e Olivier Mentré. "Synthesis and structural variety of first Mn and Bi selenites and selenite chlorides". Zeitschrift für Kristallographie - Crystalline Materials 234, n. 3 (26 marzo 2019): 141–53. http://dx.doi.org/10.1515/zkri-2018-2088.

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AbstractSingle crystals of new Mn2[Bi2O](SeO3)4(I), MnBi(SeO3)2Cl (II), MnIIMnIII(SeO3)2Cl (III), Mn5(SeO3)2Cl6(IV), and Mn4(Mn5,Bi)(SeO3)8Cl5(V) have been synthesized by chemical vapour transport and hydrothermal methods. They have been structurally characterized by single crystal X-ray diffraction analysis. The compoundsII–Vare the first Mn selenite chlorides, while theI,IIandVcompounds are the first Bi-containing Mn oxoselenites. Structural relationships of the new phases with other compounds are discussed. An overview of the mixed-ligand MnOmClnpolyhedra in inorganic compounds is given.
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6

Gospodinov, G. G., e M. G. Stancheva. "Physicochemical study on gadolinium selenites". Journal of Thermal Analysis and Calorimetry 78, n. 1 (2004): 323–29. http://dx.doi.org/10.1023/b:jtan.0000042178.46044.d1.

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7

Cao, Xue-Li, Fang Kong, Zhang-Zhen He e Jiang-Gao Mao. "Structural and magnetic studies on three new mixed metal copper(ii) selenites and tellurites". Dalton Transactions 44, n. 25 (2015): 11420–28. http://dx.doi.org/10.1039/c5dt01257k.

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8

Jia, Ying-Jie, Yi-Gang Chen, Xiao-Ni Yao e Xian-Ming Zhang. "Alkali earth MOx (x = 6, 7, 9, 12) polyhedra tuned cadmium selenites with different dimensions and diverse SeO32− coordinations". CrystEngComm 19, n. 44 (2017): 6644–50. http://dx.doi.org/10.1039/c7ce01461a.

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9

Ji, Xiao-Xu, Qing-Huai Zhao, Hao Chen, Xin-Wei Luo, Yi Shang e Xiao-Di Liu. "Facile Synthesis of Hierarchical CoSeO3‧2H2O Nanoflowers Assembled by Nanosheets as a Novel Anode Material for High-Performance Lithium-Ion Batteries". Nanomaterials 12, n. 14 (19 luglio 2022): 2474. http://dx.doi.org/10.3390/nano12142474.

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As novel anodic materials for lithium-ion batteries (LIBs), transitional metal selenites can transform into metal oxide/selenide heterostructures in the first cycle, which helps to enhance the Li+ storage performance, especially in terms of high discharge capacity. Herein, well-defined hierarchical CoSeO3‧2H2O nanoflowers assembled using 10 nm-thick nanosheets are successfully synthesized via a facile one-step hydrothermal method. When used as anodic materials for LIBs, the CoSeO3‧2H2O nanoflowers exhibit a considerably high discharge capacity of 1064.1 mAh g−1 at a current density of 0.1 A g−1. In addition, the obtained anode possesses good rate capability and cycling stability. Owing to the superior electrochemical properties, the CoSeO3‧2H2O nanoflowers would serve as promising anodic materials for high-performance LIBs.
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10

Qian, Qian, Fang Kong e Jiang-Gao Mao. "A series of new silver selenites with d0-TM cations". RSC Advances 6, n. 83 (2016): 79681–87. http://dx.doi.org/10.1039/c6ra17867g.

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11

Kong, Fang, e Jiang-Gao Mao. "Recent progress in selenite and tellurite based SHG materials". Dalton Transactions 49, n. 25 (2020): 8433–37. http://dx.doi.org/10.1039/d0dt01429j.

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12

Charkin, Dmitri O., Valeri A. Dolgikh, Timofey A. Omelchenko, Yulia A. Vaitieva, Sergey N. Volkov, Dina V. Deyneko e Sergey M. Aksenov. "Symmetry Analysis of the Complex Polytypism of Layered Rare-Earth Tellurites and Related Selenites: The Case of Introducing Transition Metals". Symmetry 14, n. 10 (7 ottobre 2022): 2087. http://dx.doi.org/10.3390/sym14102087.

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Our systematic explorations of the complex rare earth tellurite halide family have added several new [Ln12(TeO3)12][M6X24] (M = Cd, Mn, Co) representatives containing strongly deficient and disordered metal-halide layers based on transition metal cations. The degree of disorder increases sharply with decrease of M2+ radius and the size disagreements between the cationic [Ln12(TeO3)12]+12 and anionic [M6Cl24]−12 layers. From the crystal chemical viewpoint, this indicates that the families of both rare-earth selenites and tellurites can be further extended; one can expect formation of some more complex structure types, particularly among selenites. Analysis of the polytypism of compounds have been performed using the approach of OD (“order–disorder”) theory.
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13

Valkonen, J. "Crystal structures of seven cadmium selenites". Acta Crystallographica Section A Foundations of Crystallography 43, a1 (12 agosto 1987): C144. http://dx.doi.org/10.1107/s0108767387081601.

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14

Larrañaga, A., J. L. Pizarro, J. L. Mesa, R. Olazcuaga, M. I. Arriortua e T. Rojo. "Crystal structure of two related selenites". Acta Crystallographica Section A Foundations of Crystallography 61, a1 (23 agosto 2005): c367. http://dx.doi.org/10.1107/s0108767305084424.

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15

Loub, Josef. "Crystal Chemistry of the Hydrogen Selenites MH2n+1(SeO3)n+1". Collection of Czechoslovak Chemical Communications 60, n. 7 (1995): 1071–80. http://dx.doi.org/10.1135/cccc19951071.

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Abstract (sommario):
Thirty six SeO3 formations in 17 crystal structures of selenites with formula MH2n+1(SeO3)n+1 , where M = H, Li, Na, K, Rb, Cs, NH4, Tl and n = 0-3 were analysed in this paper. There are found five types of selenites: SeO(OH)2 (n = 14), SeO2(OH)- (n = 17), SeO(OH0.5)2-(n = 1), Se(OH0.5)30.5-(n = 3) and SeO(OH)(OH0.5)0.5- (n = 1). All formations SeO3 have the point symmetry 1. The overall mean value of 108 individual Se-O distances is 1.70(5) Å, of 108 O-Se-O angles is 101(3) grad. and of 57 O...O distances in hydrogen bonds is 2.60(6) Å. A very significant correlation was found between the ionic radius r (Å) of the element M and the value V/Z (Å3).
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16

Rao, C. N. R., J. N. Behera e Meenakshi Dan. "Organically-templated metal sulfates, selenites and selenates". Chemical Society Reviews 35, n. 4 (2006): 375. http://dx.doi.org/10.1039/b510396g.

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17

Adler, Philip D. F., Rosalind Xu, Jacob H. Olshansky, Matthew D. Smith, Katherine C. Elbert, Yunwen Yang, Gregory M. Ferrence, Matthias Zeller, Joshua Schrier e Alexander J. Norquist. "Probing structural adaptability in templated vanadium selenites". Polyhedron 114 (agosto 2016): 184–93. http://dx.doi.org/10.1016/j.poly.2015.11.038.

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18

Pasha, Intyaj, Amitava Choudhury e C. N. R. Rao. "Organically Templated Vanadyl Selenites with Layered Structures". Inorganic Chemistry 42, n. 2 (gennaio 2003): 409–15. http://dx.doi.org/10.1021/ic020479r.

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19

Castro, A., M. de Pedro e I. Rasines. "Thermal decomposition of novel rare-earth selenites". Journal of Thermal Analysis 40, n. 3 (settembre 1993): 1109–14. http://dx.doi.org/10.1007/bf02546871.

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20

Lukevics, Edmunds, Pavel Arsenyan, Irina Shestakova, Ilona Domracheva, Iveta Kanepe, Sergey Belyakov, Juris Popelis e Olga Pudova. "Synthesis, structure and cytotoxicity of organoammonium selenites". Applied Organometallic Chemistry 16, n. 4 (2002): 228–34. http://dx.doi.org/10.1002/aoc.276.

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21

Vlaev, L. T., V. G. Georgieva e S. D. Genieva. "Kinetic parameters of decomposition of some selenites". Journal of Thermal Analysis and Calorimetry 83, n. 2 (febbraio 2006): 421–27. http://dx.doi.org/10.1007/s10973-005-6918-y.

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22

Mandarino, Joseph A. "Natural and synthetic selenites and selenates and their Gladstone-Dale compatibility". European Journal of Mineralogy 6, n. 3 (7 giugno 1994): 337–50. http://dx.doi.org/10.1127/ejm/6/3/0337.

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23

Kovrugin, Vadim M., Oleg I. Siidra, Olivier Mentré e Sergey V. Krivovichev. "Structural variety of novel Pb and Bi selenites". Acta Crystallographica Section A Foundations of Crystallography 69, a1 (25 agosto 2013): s134. http://dx.doi.org/10.1107/s0108767313098875.

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24

Canossa, Stefano, Enrico Bellè, Massimiliano Delferro, Giovanni Predieri e Claudia Graiff. "Structural motifs in heteroleptic copper and cadmium selenites". Inorganica Chimica Acta 470 (gennaio 2018): 206–12. http://dx.doi.org/10.1016/j.ica.2017.05.043.

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25

Gospodinov, G. G., e M. G. Stancheva. "A physicochemical study of the selenites of yttrium". Crystal Research and Technology 29, n. 7 (1994): K83—K88. http://dx.doi.org/10.1002/crat.2170290719.

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26

Liang, Ming-Li, Yun-Xiang Ma, Chun-Li Hu, Fang Kong e Jiang-Gao Mao. "A(VO2F)(SeO3) (A = Sr, Ba) and Ba(MOF2)(TeO4) (M = Mo, W): first examples of alkali-earth selenites/tellurites with a fluorinated d0-TM octahedron". Dalton Transactions 47, n. 5 (2018): 1513–19. http://dx.doi.org/10.1039/c7dt04442a.

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Abstract (sommario):
First examples of alkali-earth selenites/tellurites with a fluorinated d0-TM octahedron, namely, A(VO2F)(SeO3) (A = Sr 1, Ba 2) and Ba(MOF2)(TeO4) (M = Mo 3, W 4), were synthesized successfully by hydrothermal reactions.
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27

Mička, Zdeněk, Miroslav Ebert e Pavel Ptáček. "Preparation of potassium selenites, their solubility and bonding conditions". Collection of Czechoslovak Chemical Communications 51, n. 12 (1986): 2741–50. http://dx.doi.org/10.1135/cccc19862741.

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The solubility diagrams of a K2SeO3-H2SeO3-H2O system were studied at 293 and 303 K for the first time. The effect of temperature on the character of the studied system from the point of view of the transition from hydrogenselenite to diselenite was studied. The results were used to refine the preparation conditions for K5H3(SeO3)4, KHSeO3, KH3(SeO3)2, and K2Se2O5. The compounds obtained were studied using thermoanalytical methods and infrared spectroscopy. The behaviour of protons in the hydrogen bonds of the acid salts was described.
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28

Tsukamoto, Takeyo, Jun Hatano e Hideo Futama. "Light deflection by ferroelastic domains in alkaline trihydrogen selenites". Ferroelectrics 64, n. 1 (giugno 1985): 189–96. http://dx.doi.org/10.1080/00150198508018720.

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29

Mao, Jiang-Gao, Hai-Long Jiang e Fang Kong. "Structures and Properties of Functional Metal Selenites and Tellurites". Inorganic Chemistry 47, n. 19 (6 ottobre 2008): 8498–510. http://dx.doi.org/10.1021/ic8005629.

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30

de Pedro, M., J. C. Trombe e A. Castro. "On the rare-earth selenites Pr2Se4O11, R2Se3O9 and R2SeO5". Journal of Materials Science Letters 14, n. 14 (gennaio 1995): 994–97. http://dx.doi.org/10.1007/bf00274629.

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31

Choudhury, Amitava, Udaya Kumar D e C. N. R. Rao. "Three-Dimensional Organically Templated Open-Framework Transition Metal Selenites". Angewandte Chemie International Edition 41, n. 1 (2 gennaio 2002): 158–61. http://dx.doi.org/10.1002/1521-3773(20020104)41:1<158::aid-anie158>3.0.co;2-#.

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32

Choudhury, Amitava, Udaya Kumar D e C. N. R. Rao. "Three-Dimensional Organically Templated Open-Framework Transition Metal Selenites". Angewandte Chemie 114, n. 1 (4 gennaio 2002): 166–69. http://dx.doi.org/10.1002/1521-3757(20020104)114:1<166::aid-ange166>3.0.co;2-m.

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33

De Pedro, M., I. Rasines e A. Castro. "Synthesis and characterization of new anhydrous rare-earth selenites". Journal of Materials Science Letters 12, n. 20 (gennaio 1993): 1637–40. http://dx.doi.org/10.1007/bf00627037.

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34

Krivovichev, Vladimir G., Sergey V. Krivovichev e Marina V. Charykova. "Selenium Minerals: Structural and Chemical Diversity and Complexity". Minerals 9, n. 7 (23 luglio 2019): 455. http://dx.doi.org/10.3390/min9070455.

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Abstract (sommario):
Chemical diversity of minerals containing selenium as an essential element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 123 Se mineral species approved by the International Mineralogical Association as of 25 May 2019. All known selenium minerals belong to seven mineral systems with the number of essential components ranging from one to seven. According to their chemical features, the minerals are subdivided into five groups: Native selenium, oxides, selenides, selenites, and selenates. Statistical analysis shows that there are strong and positive correlations between the chemical and structural complexities (measured as amounts of Shannon information per atom and per formula or unit cell) and the number of different chemical elements in a mineral. Analysis of relations between chemical and structural complexities provides strong evidence that there is an overall trend of increasing structural complexity with the increasing chemical complexity. The average structural complexity for Se minerals is equal to 2.4(1) bits per atom and 101(17) bits per unit cell. The chemical and structural complexities of O-free and O-bearing Se minerals are drastically different with the first group being simpler and the second group more complex. The O-free Se minerals (selenides and native Se) are primary minerals; their formation requires reducing conditions and is due to hydrothermal activity. The O-bearing Se minerals (oxides and oxysalts) form in near-surface environment, including oxidation zones of mineral deposits, evaporites and volcanic fumaroles. From the structural viewpoint, the five most complex Se minerals are marthozite, Cu(UO2)3(SeO3)2O2·8H2O (744.5 bits/cell); mandarinoite, Fe2(SeO3)3·6H2O (640.000 bits/cell); carlosruizite, K6Na4Na6Mg10(SeO4)12(IO3)12·12H2O (629.273 bits/cell); prewittite, KPb1.5ZnCu6O2(SeO3)2Cl10 (498.1 bits/cell); and nicksobolevite, Cu7(SeO3)2O2Cl6 (420.168 bits/cell). The mechanisms responsible for the high structural complexity of these minerals are high hydration states (marthozite and mandarinoite), high topological complexity (marthozite, mandarinoite, carlosruizite, nicksobolevite), high chemical complexity (prewittite and carlosruizite), and the presence of relatively large clusters of atoms (carlosruizite and nicksobolevite). In most cases, selenium itself does not play the crucial role in determining structural complexity (there are structural analogues or close species of marthozite, mandarinoite, and carlosruizite that do not contain Se), except for selenite chlorides, where stability of crystal structures is adjusted by the existence of attractive Se–Cl closed-shell interactions impossible for sulfates or phosphates. Most structurally complex Se minerals originate either from relatively low-temperature hydrothermal environments (as marthozite, mandarinoite, and carlosruizite) or from mild (500–700 °C) anhydrous gaseous environments of volcanic fumaroles (prewittite, nicksobolevite).
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Charykova, M. V., E. L. Fokina, E. V. Klimova, V. G. Krivovichev e V. V. Semenova. "Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. IX. Physicochemical formation conditions and thermal stability of zinc selenites". Geology of Ore Deposits 56, n. 7 (dicembre 2014): 546–52. http://dx.doi.org/10.1134/s1075701514070046.

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Gurzhiy, Vladislav V., Ivan V. Kuporev, Vadim M. Kovrugin, Mikhail N. Murashko, Anatoly V. Kasatkin e Jakub Plášil. "Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites". Crystals 9, n. 12 (30 novembre 2019): 639. http://dx.doi.org/10.3390/cryst9120639.

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Abstract (sommario):
Comparison of the natural and synthetic phases allows an overview to be made and even an understanding of the crystal growth processes and mechanisms of the particular crystal structure formation. Thus, in this work, we review the crystal chemistry of the family of uranyl selenite compounds, paying special attention to the pathways of synthesis and topological analysis of the known crystal structures. Comparison of the isotypic natural and synthetic uranyl-bearing compounds suggests that uranyl selenite mineral formation requires heating, which most likely can be attributed to the radioactive decay. Structural complexity studies revealed that the majority of synthetic compounds have the topological symmetry of uranyl selenite building blocks equal to the structural symmetry, which means that the highest symmetry of uranyl complexes is preserved regardless of the interstitial filling of the structures. Whereas the real symmetry of U-Se complexes in the structures of minerals is lower than their topological symmetry, which means that interstitial cations and H2O molecules significantly affect the structural architecture of natural compounds. At the same time, structural complexity parameters for the whole structure are usually higher for the minerals than those for the synthetic compounds of a similar or close organization, which probably indicates the preferred existence of such natural-born architectures. In addition, the reexamination of the crystal structures of two uranyl selenite minerals guilleminite and demesmaekerite is reported. As a result of the single crystal X-ray diffraction analysis of demesmaekerite, Pb2Cu5[(UO2)2(SeO3)6(OH)6](H2O)2, the H atoms positions belonging to the interstitial H2O molecules were assigned. The refinement of the guilleminite crystal structure allowed the determination of an additional site arranged within the void of the interlayer space and occupied by an H2O molecule, which suggests the formula of guilleminite to be written as Ba[(UO2)3(SeO3)2O2](H2O)4 instead of Ba[(UO2)3(SeO3)2O2](H2O)3.
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Глотова (Glotova), Ирина (Irina) Анатольевна (Anatol'evna), e Надежда (Nadezhda) Алексеевна (Alekseevna) Галочкина (Galochkina). "INFLUENCE OF SOURCES OF SELENIUM ON BIOCHEMICAL PROCESSES DURING SWELLING AND GERMINATION OF WHEAT GRAIN". chemistry of plant raw material, n. 4 (2 giugno 2017): 211–16. http://dx.doi.org/10.14258/jcprm.2017041849.

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The influence of sodium selenite and 4,4-di[3(5-methylpiperazine)]selenide (DMDPS) on microphenological phases of swelling and germination of grain of winter wheat of a grade "Alaya Zarya" was studied. The influence of sodium selenite and DMDPS on amylolytic, proteolytic activity and contents in the form of glutathione is studied. Opposite action of DMDPS and selenit on biochemical processes at grain germination is found: for DMDPS – stimulating, for sodium selenit – depressant. Under the influence of sodium selenit the decrease in proteolytic activity by 30%, under the influence of DMDPS – 5% is revealed. It is found that amylolytic activity of wheat under the influence of DMDPS shows a tendency to achieve the same level, as in the control "Wheat + H2O", however the maximum is reached 4 hours earlier. In a sample with sodium selenit the decrease in amylolytic activity by 15% in comparison with control is found. Stimulating action of DMDPS on glutathione accumulation is detected. The maximum contents in the form of glutathione is noted for a sample of wheat, germinated with DMDPS – 8,53 mg%. It is 22,6% more than in the control sample, and is 36,1% more, than in the sample with sodium selenit. The extreme values of an indicator are reached in 28 hours of germination for the control sample, in 16–20 hours – for samples with DMDPS and Na2SeO3. The duration of microphenological phases of germination of seeds using DMDPS as a part of steep water is reduced by 2–4 hours in comparison with tap water. The results are used for control of wheat grain germination in the process of additives enriched with selenium on grain basis.
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38

Kovrugin, Vadim M., Marie Colmont, Olivier Mentré, Oleg I. Siidra e Sergey V. Krivovichev. "Modular crystallography of novel copper selenites and selenates: experimental mineralogy". Acta Crystallographica Section A Foundations and Advances 73, a2 (1 dicembre 2017): C84. http://dx.doi.org/10.1107/s2053273317094876.

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39

Ionashiro, M., C. B. Melios, C. A. Ribeiro, M. Spirandeli Crepsi e I. Giolito. "Thermal decomposition of hydrated selenites of trivalent lanthanides and yttrium". Thermochimica Acta 168 (ottobre 1990): 223–32. http://dx.doi.org/10.1016/0040-6031(90)80641-b.

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40

Gospodinov, G., Yu Slavcheva e E. Popova. "Determination of the thermodynamic parameters of some slightly soluble selenites". Thermochimica Acta 181 (maggio 1991): 337–39. http://dx.doi.org/10.1016/0040-6031(91)80435-l.

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41

Shin, Na Hye, Yoo Jin Lim, Chorong Kim, Ye Eun Kim, Yu Ra Jeong, Hyunsung Cho, Myung-Sook Park e Sang Hyup Lee. "An Efficient Method for Selective Syntheses of Sodium Selenide and Dialkyl Selenides". Molecules 27, n. 16 (16 agosto 2022): 5224. http://dx.doi.org/10.3390/molecules27165224.

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The studies on the selective synthesis of dialkyl selenide compounds 1 were presented. Overcoming the complexity and difficulty of selenides (R-Se-R) and/or multiselenides (R-Sen-R; n ≥ 2), we aimed to optimize the reaction condition for the tolerable preparation of sodium selenide (Na2Se) by reducing Se with NaBH4, and then to achieve selective syntheses of dialkyl selenides 1 by subsequently treating the obtained sodium selenide with alkyl halides (RX). Consequently, various dialkyl selenides 1 were efficiently synthesized in good-to-moderate yields. The investigations on reaction pathways and solvent studies were also described.
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42

Christensen, M. K., C. J. Frederickson e G. Danscher. "Retrograde tracing of zinc-containing neurons by selenide ions: a survey of seven selenium compounds." Journal of Histochemistry & Cytochemistry 40, n. 4 (aprile 1992): 575–79. http://dx.doi.org/10.1177/40.4.1313065.

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The autometallographic retrograde tracing of zinc-containing neurons by intracerebral injection of sodium selenite (Na2SeO3), introduced by Danscher in 1982, has recently been described in more detail. Intracerebral injections of both sodium selenide (Na2Se) and sodium selenite (Na2SeO3) have been successfully used; however, sodium selenite had a rather toxic effect on the injected tissue. In the present study, we tested seven different selenium compounds to find the most suitable compound for retrograde tracing of zinc-positive pathways. Among the tested compounds, sodium selenide (Na2Se) caused insignificant necrosis within the injection site and was easily transported retrogradely when handled anaerobically. Sodium selenide is therefore recommended as the compound of choice.
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43

Kong, Fang, Pei-Xin Li, Su-Yun Zhang e Jiang-Gao Mao. "Explorations of new selenites of the group IIIA and IVA metals". Journal of Solid State Chemistry 190 (giugno 2012): 118–25. http://dx.doi.org/10.1016/j.jssc.2012.02.014.

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44

Nasluzova, O. I., I. S. Vinogradova, A. G. Lundin e L. L. Zhidkov. "NMR and Raman spectral studies of ammonium hydrogen selenites single crystals". Solid State Sciences 6, n. 12 (dicembre 2004): 1381–85. http://dx.doi.org/10.1016/j.solidstatesciences.2004.06.005.

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45

Lelet, Maxim I., Marina V. Charykova, Vladimir G. Krivovichev, Nataliya M. Efimenko, Natalia V. Platonova e Evgeny V. Suleimanov. "A calorimetric and thermodynamic investigation of zinc and cadmium hydrous selenites". Journal of Chemical Thermodynamics 115 (dicembre 2017): 63–73. http://dx.doi.org/10.1016/j.jct.2017.07.020.

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46

Kovrugin, Vadim M., Marie Colmont, Oleg I. Siidra, Sergey V. Krivovichev e Olivier Mentré. "Exploration of Vanadate Selenites Solid Phase Space, Crystal Structures, and Polymorphism". Crystal Growth & Design 16, n. 6 (2 maggio 2016): 3113–23. http://dx.doi.org/10.1021/acs.cgd.5b01706.

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47

Wickleder, Mathias S. "NdClSeO3 and ErClSeO3: First Chloride-Selenites of the Rare Earth Elements". Zeitschrift für Naturforschung B 57, n. 12 (1 dicembre 2002): 1414–18. http://dx.doi.org/10.1515/znb-2002-1212.

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Abstract (sommario):
Violet single crystals of NdClSeO3 (Pnma, Z = 8, a = 1115.3(2), b = 535.19(6), c = 1356.8(1) pm, Rall = 0.0281) were obtained from the reaction of Nd2O3, NdCl3, and SeO2 in evacuated silica ampoules. The analogous procedure using Er2O3 and ErCl3 led to pink single crystals of ErClSeO3 (Pnma, Z = 4, a = 721.8(1), b = 692.2(1), c = 874.3(2) pm, Rall = 0.0305). The crystal structure of NdClSeO3 contains two crystallographically different neodymium ions. Nd(2)3+ is coordinated by four oxygen atoms and four chloride ions while eight oxygen atoms and one Cl− ion are connected to Nd(1)3+. The linkage of the polyhedra leads to a three-dimensional structure. In the structure of ErClSeO3 the Er3+ ion is coordinated by two Cl− ions, three O-monodentate SeO32− and one O,O-chelating SeO32− groups. The [ErO5Cl2] polyhedra can be seen as pentagonal bipyramids, which are connected in the [010] direction via opposite edges of oxygen atoms to infinite chains. These are further linked via chloride ions to give a three-dimensional network. In both crystal structures a prominent stereochemical activity of the lone electron pairs of the selenite ions can be observed.
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48

Choudhury, Amitava, Udaya Kumar D e C. N. R. Rao. "ChemInform Abstract: Three-Dimensional Organically Templated Open-Framework Transition Metal Selenites." ChemInform 33, n. 18 (21 maggio 2010): no. http://dx.doi.org/10.1002/chin.200218009.

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49

Martynov, Alexander V., Nataliya A. Makhaeva, Maxim V. Musalov, Alexander I. Albanov e Svetlana V. Amosova. "Pd/Cu-Catalyzed Cross-Coupling of Bis(2-bromovinyl) Selenides with Terminal Acetylenes: Unusual Involvement of Selanyl Function in the Sonogashira Reaction". Catalysts 12, n. 12 (6 dicembre 2022): 1589. http://dx.doi.org/10.3390/catal12121589.

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The Pd/Cu-catalyzed Sonogashira reaction of (E,E)-bis(2-bromovinyl) selenide and (E,E)-bis(1-bromo-1-hexen-2-yl) selenide with terminal alkynes was found to proceed at room temperature involving both bromine atoms and the selanyl function. As a result, new bis-(1,3-enynyl) selenides and enediyne hydrocarbons are formed with a complete retention of the stereoconfiguration of the initial selenides. Due to steric hindrances in the cross-coupling at the selenyl function in the case of (E,E)-bis(1-bromo-1-hexen-2-yl) selenide, the second process is realized to a lesser extent than with unsubstituted (E,E)-bis(2-bromovinyl) selenide.
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50

Sarret, Géraldine, Laure Avoscan, Marie Carrière, Richard Collins, Nicolas Geoffroy, Francine Carrot, Jacques Covès e Barbara Gouget. "Chemical Forms of Selenium in the Metal-Resistant Bacterium Ralstonia metallidurans CH34 Exposed to Selenite and Selenate". Applied and Environmental Microbiology 71, n. 5 (maggio 2005): 2331–37. http://dx.doi.org/10.1128/aem.71.5.2331-2337.2005.

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ABSTRACT Ralstonia metallidurans CH34, a soil bacterium resistant to a variety of metals, is known to reduce selenite to intracellular granules of elemental selenium (Se0). We have studied the kinetics of selenite (SeIV) and selenate (SeVI) accumulation and used X-ray absorption spectroscopy to identify the accumulated form of selenate, as well as possible chemical intermediates during the transformation of these two oxyanions. When introduced during the lag phase, the presence of selenite increased the duration of this phase, as previously observed. Selenite introduction was followed by a period of slow uptake, during which the bacteria contained Se0 and alkyl selenide in equivalent proportions. This suggests that two reactions with similar kinetics take place: an assimilatory pathway leading to alkyl selenide and a slow detoxification pathway leading to Se0. Subsequently, selenite uptake strongly increased (up to 340 mg Se per g of proteins) and Se0 was the predominant transformation product, suggesting an activation of selenite transport and reduction systems after several hours of contact. Exposure to selenate did not induce an increase in the lag phase duration, and the bacteria accumulated approximately 25-fold less Se than when exposed to selenite. SeIV was detected as a transient species in the first 12 h after selenate introduction, Se0 also occurred as a minor species, and the major accumulated form was alkyl selenide. Thus, in the present experimental conditions, selenate mostly follows an assimilatory pathway and the reduction pathway is not activated upon selenate exposure. These results show that R. metallidurans CH34 may be suitable for the remediation of selenite-, but not selenate-, contaminated environments.
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