177,181 research outputs found
Correlations Between Effective Crystal Radii and Unit Cell Volume in Tutton Salts
No full textThe unit cell volumes of 29 Tutton salts (the general formula of which is M2IMn(XY4)2 • 6H2O) were retrieved from the literature. Assuming that the unit cell volume may be represented by a function of the type: V = a + b R(M+) + c J?(M2 +) + d RQt-Y) + e Ey (R(M+) where R(M2+) are the effective crystal radii of the uni- and divalent cations, respectively, J?(X-Y) is the X-Y distance in the tetrahedral anion and Ey is the Pauling electronegativity of the Y atoms, the multiple linear regression analysis was applied.
The agreement between the observed and the predicted values of V is rather good (adjusted r2 = 0.966), thus allowing to predict the values for effective crystal radii of ions that have not been published so far. In line with this, the Ru-Tutton salts are predicted to be low-spin Ru2+ hexaaquacomplexes.
Some points concerning the possibility of the existence of particular iso- morphs are also discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Temperature-Induced Phase Transformations in Tutton Salt K2Cu(SO4)2(H2O)6: Thermoanalytical Studies Combined with Powder X-Ray Diffraction
No full textTutton salts have received considerable attention due to their potential applications in thermochemical energy storage (TCHS) systems. This technology requires high-purity materials that exhibit reversible dehydration reactions, significant variations in dehydration enthalpy, and high-temperature melting points. In this study, K2Cu(SO4)2(H2O)6 Tutton salt in the form of single crystals was grown using the slow solvent evaporation method. Their structural, morphological, and thermal characteristics are presented and discussed, as well as temperature-induced phase transformations. At room temperature, the salt crystallizes in a monoclinic structure belonging to the P21/a space group, which is typical for Tutton salts. The lack of precise control over the solvent evaporation rate during crystal growth introduced structural disorder, resulting in defects on the crystal surface, including layer discontinuities, occlusions, and pores. Thermoanalytical analyses revealed two stages of mass loss, corresponding to the release of 4 + 2 coordinated H2O molecules—four weakly coordinated and two strongly coordinated to the copper. The estimated dehydration enthalpy was ≈ 80.8 kJ/mol per mole of H2O. Powder X-ray diffraction measurements as a function of temperature showed two phase transformations associated with the complete dehydration of the starting salt occurring between 28 and 160 °C, further corroborating the thermal results. The total dehydration up to ≈ 160 °C, high enthalpy associated with this process, and high melting point temperature make K2Cu(SO4)2(H2O)6 a promising candidate for TCHS applications
Insight into Compounds with Cu(H<sub>2</sub>O)<sub>6</sub><sup>2+</sup> Units: New Ideas for Understanding Cu<sup>2+</sup> in Tutton Salts
No full textIn the last 65 years the properties of Tutton salts containing Cu2+ cations have been interpreted on the basis of elongated complexes induced by a static Jahn–Teller effect (JTE). Through the analysis of experimental data and the results of first-principles calculations, we show here that such an idea, though widely followed, is not correct. By contrast, this work proves that the local geometry of Cu(H2O)62+ units in Tutton salts actually arises from a compressed octahedron although hidden by an additional orthorhombic instability fully unrelated to the JTE. For understanding this conclusion, it is crucial to consider the effects of the internal electric field, ER(r), created by the rest of the lattice ions on the electrons localized in the Cu(H2O)62+ unit. Indeed, the ER(r) field in Tutton salts opens a gap between ∼x2–y2 and ∼3z2–r2 antibonding molecular orbitals that favors a hole in ∼3z2–r2 and triggers an orthorhombic distortion in the XY plane that reasonably explains available experimental data. The conditions responsible for the orthorhombic instability are discussed pointing out the singularity of Cu2+ complexes in the realm of 3d divalent cations. For the sake of completeness the properties of Cu(H2O)62+ units in trigonal lattices, where a JTE is clearly observed, are analyzed in detail and compared to results of Cu2+ cations in cubic lattices. In the trigonal compounds, the force constant of the Jahn–Teller mode is shown to be smaller than that for hard ligands like O2– or F– but comparable to the softer ligand Cl–. This fact helps to promote the orthorhombic instability in the Cu(H2O)62+ complex when the hole is no longer in the ∼x2–y2 orbital but in ∼3z2–r2
Letter from R. R. Zellick, Assistant Trust Officer, Anglo California National Bank of San Francisco, to Joseph R. Goodman, October 2, 1942
No full textLetter from R. R. Zellick, Assistant Trust Officer at The Anglo California National Bank of San Francisco, to Joseph R. Goodman, regarding property owned by Dave Tatsuno. Zellick mentions a dispute between current tenants and Tatsuno, and that Tatsuno has asked Goodman to help locate trustworthy tenants.Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Liftings for noncomplete probability spaces
No full textThe current state of knowledge concerning liftings for noncomplete probability spaces is discussed. This is a somewhat expanded version of the author's talk given at the 1991 Summer Conference on General Topology and Applications in Honor of Mary Ellen Rudin and Her Work.PT: S; CR: BURKE MR, IN PRESS P AM MATH S BURKE MR, 1991, ISRAEL J MATH, V73, P33 BURKE MR, 1992, ISRAEL J MATH, V79, P289 CARLSON T, THEOREM LIFTING CHRISTENSEN JPR, 1974, TOPOLOGY BOREL STRUC FREMLIN DH, 1989, HDB BOOLEAN ALGEBRAS, P877 INOESCUTULCEA A, 1966, 5TH P BERK S MATH ST, V2 IONESCUTULCEA A, 1967, CONTRIBUTIONS PROB 1, P63 IONESCUTULCEA A, 1969, TOPICS THEORY LIFTIN JECH TJ, 1978, SET THEORY JOHNSON RA, 1980, P AM MATH SOC, V80, P234 JUST W, IN PRESS T AM MATH S KUPKA J, 1983, INDIANA U MATH J, V32, P717 LOSERT V, 1983, LNM, V1080, P95 MAHARAM D, 1958, P AM MATH SOC, V9, P987 SHELAH S, 1983, ISRAEL J MATH, V45, P90 TALAGRAND M, 1982, P AM MATH SOC, V84, P379 VONNEUMANN J, 1931, CRELLES J MATH, V165, P109; NR: 18; TC: 0; J9: ANN N Y ACAD SCI; PG: 4; GA: BZ86BSource type: Electronic(1
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