Crystal chemistry and stability of "Li7La3Zr2O12" garnet: a fast lithium-ion conductor

Recent research has shown that certain Li-oxide garnets with high mechanical, thermal, chemical, and electrochemical stability are excellent fast Li-ion conductors. However, the detailed crystal chemistry of Li-oxide garnets is not well understood, nor is the relationship between crystal chemistry and conduction behavior. An investigation was undertaken to understand the crystal chemical and structural properties, as well as the stability relations, of Li(7)La(3)Zr(2)O(12) garnet, which is the best conducting Li-oxide garnet discovered to date. Two different sintering methods produced Li-oxide garnet but with slightly different compositions and different grain sizes. The first sintering method, involving ceramic crucibles in initial synthesis steps and later sealed Pt capsules, produced single crystals up to roughly 100 μm in size. Electron microprobe and laser ablation inductively coupled plasma mass spectrometry (ICP-MS) measurements show small amounts of Al in the garnet, probably originating from the crucibles. The crystal structure of this phase was determined using X-ray single-crystal diffraction every 100 K from 100 K up to 500 K. The crystals are cubic with space group Ia3?d at all temperatures. The atomic displacement parameters and Li-site occupancies were measured. Li atoms could be located on at least two structural sites that are partially occupied, while other Li atoms in the structure appear to be delocalized. (27)Al NMR spectra show two main resonances that are interpreted as indicating that minor Al occurs on the two different Li sites. Li NMR spectra show a single narrow resonance at 1.2-1.3 ppm indicating fast Li-ion diffusion at room temperature. The chemical shift value indicates that the Li atoms spend most of their time at the tetrahedrally coordinated C (24d) site. The second synthesis method, using solely Pt crucibles during sintering, produced fine-grained Li(7)La(3)Zr(2)O(12) crystals. This material was studied by X-ray powder diffraction at different temperatures between 25 and 200 °C. This phase is tetragonal at room temperature and undergoes a phase transition to a cubic phase between 100 and 150 °C. Cubic "Li(7)La(3)Zr(2)O(12)" may be stabilized at ambient conditions relative to its slightly less conducting tetragonal modification via small amounts of Al(3+). Several crystal chemical properties appear to promote the high Li-ion conductivity in cubic Al-containing Li(7)La(3)Zr(2)O(12). They are (i) isotropic three-dimensional Li-diffusion pathways, (ii) closely spaced Li sites and Li delocalization that allow for easy and fast Li diffusion, and (iii) low occupancies at the Li sites, which may also be enhanced by the heterovalent substitution Al(3+) ? 3Li.     

Asymmetric integral as a limit of generated Choquet integrals based on absolutely monotone real set functions

We introduce a generated Choquet integral with respect to absolutely monotone and sign stable set functions. Another type of integrals defined with respect to such a set function is obtained as a limit of an appropriate sequence of generated Choquet integrals.     

Factorial-Based Designs in Liquid Chromatography

In this paper, the review on application of factorial-based designs in liquid chromatography (LC) is given. The most useful and applicable full factorial design and reduced forms of full factorial design (fractional factorial design and Plackett–Burman design) applied in LC are presented. Literature survey shows that experimental design presents very often used tool in screening, optimization and robustness testing of LC methods.     

Characterization of pottery from Republic of Macedonia. III. A study of comparative mineralogical detection efficiency using micro‐Raman mapping and X‐ray diffraction

Point‐to‐point micro‐Raman and X‐ray diffraction (XRD) techniques were employed for characterization of minerals present in the pottery body of 27 glazed Byzantine and Ottoman pottery shreds, excavated at two different archaeological sites in the Republic of Macedonia: in Skopje (Skopsko Kale) and in Prilep (Markovi Kuli and Sv. Atanas Church). The Raman spectra of 18 Byzantine samples (dating from 12th−14th century) and nine Ottoman samples (dating from 17th−19th century) revealed 26 different minerals. XRD measurements were further performed on the same powder samples to validate the mineralogical assessment obtained by point‐to‐point micro‐Raman spectroscopy. Although only 13 different mineral phases were obtained by the XRD, the results obtained from the Raman and XRD spectra for the most abundant minerals in the investigated pottery bodies match quite well. However, the identification of the less abundant minerals in the clay matrixes from the XRD data was very difficult, if at all possible. The results emphasize the specifics of the applied techniques and their limits. Additionally, wavelength dispersive X‐ray fluorescence spectroscopy was used for the elemental analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct Zinc Finger Protein Persulfidation by H2S Is Facilitated by Zn2+

H₂S is a gaseous signaling molecule that modifies cysteine residues in proteins to form persulfides (P‐SSH). One family of proteins modified by H₂S are zinc finger (ZF) proteins, which contain multiple zinc‐coordinating cysteine residues. Herein, we report the reactivity of H₂S with a ZF protein called tristetraprolin (TTP). Rapid persulfidation leading to complete thiol oxidation of TTP mediated by H₂S was observed by low‐temperature ESI‐MS and fluorescence spectroscopy. Persulfidation of TTP required O₂ , which reacts with H₂S to form superoxide, as detected by ESI‐MS, a hydroethidine fluorescence assay, and EPR spin trapping. H₂S was observed to inhibit TTP function (binding to TNFα mRNA) by an in vitro fluorescence anisotropy assay and to modulate TNFα in vivo. H₂S was unreactive towards TTP when the protein was bound to RNA, thus suggesting a protective effect of RNA.     

The H+NO recombination reaction over a wide temperature range

Rate coefficients of the title reaction have been measured in a high‐temperature photochemistry (HTP) reactor using Ar as the bath gas. H atoms were generated by flash photolysis of NH₃ and their relative concentrations were monitored by resonance fluorescence. The data are best fitted by k(295–905 K) = 6.5 × 10^?34 (T/K)^0.206 exp(780K T) cm⁶ molecule^?2 s^?1, with ±2σ precision values varying from 16 to 36% and corresponding suggested accuracy levels of 29–42%. Using a literature value for the relative collision efficiencies of N₂ and Ar indicates that for N₂ as the third body the above rate coefficient expression should be multiplied by 1.6. This leads to good agreement with two recent near 1000 K measurements. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 374–380, 2003     

Liquid order at the interface of KDP crystals with water: evidence for icelike layers

We present a surface x-ray diffraction study on the KDP-water interface in which the structure of both the crystalline and liquid part of the interface has been measured. We have been able to determine the ordering components in the liquid in both the perpendicular and parallel directions. We find interface-induced ordering in the first four layers of water molecules. The first two layers behave icelike and are strongly bound to the surface. The next two layers are more diffuse and show only minor lateral and perpendicular ordering. Subsequent layers are found to behave similar to a bulk liquid.     

Heteropentanuclear Oxalato‐Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis,Crystal Structures,Aqueous Stability and Antiproliferative Activity

A series of heteropentanuclear oxalate‐bridged Ru(NO)‐Ln (4d–4f) metal complexes of the general formula (nBu₄N)₅[Ln{RuCl₃(μ‐ox)(NO)}₄], where Ln=Y ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ) and ox=oxalate anion, were obtained by treatment of (nBu₄N)₂[RuCl₃(ox)(NO)] ( 1 ) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1 , 2 , and 5 were in addition analyzed by X‐ray crystallography, 1 by Ru K‐edge XAS and 1 and 2 by ¹³C NMR spectroscopy. X‐ray diffraction showed that in 2 and 5 four complex anions [RuCl₃(ox)(NO)]^2? are coordinated to Y^III and Dy^III, respectively, with formation of [Ln{RuCl₃(μ‐ox)(NO)}₄]^5? (Ln=Y, Dy). While Y^III is eight‐coordinate in 2 , Dy^III is nine‐coordinate in 5 , with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu₄N⁺ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium‐lanthanide complexes 2 – 5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC‐5) and compared with those obtained for the previously reported Os(NO)‐Ln (5d–4f) analogues (nBu₄N)₅[Ln{OsCl₃(ox)(NO)}₄] (Ln=Y ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 )). Complexes 2 – 5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6 – 9 in terms of IC₅₀ values. The highest antiproliferative activity with IC₅₀ values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP‐MS data, indicating five‐ to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells.