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Rb2Lu[Si4O10]F, a tubular chain silicate.

ABSTRACT: Single crystals of Rb2Lu[Si4O10]F (dirubidium lutetium tetra-silicate fluoride) were obtained in flux-synthesis experiments in the system SiO2-Lu2O3-RbF. The compound belongs to the group of tubular chain silicates, i.e. it is based on multiple chains of condensed [SiO4] tetra-hedra forming closed columns. The periodicity of the unbranched multiple chains is four and corresponds to the length of the b axis. Adjacent columns are connected by Lu(3+) cations, which are coordinated by four oxide and two fluoride anions in the form of slightly distorted octa-hedra. By sharing common fluoride corners, the single octa-hedra are linked into chains running parallel to the silicate tubes. Electroneutrality is achieved by the incorporation of additional Rb(+) cations. All four symmetrically independent rubidium ions, four out of twelve oxide as well as the two fluoride anions are located on mirror planes. The remaining atoms reside on general positions.

SUBMITTER: Kahlenberg V

PROVIDER: S-EPMC3998444 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Rb2Lu[Si4O10]F, a tubular chain silicate.

Kahlenberg Volker V Manninger Tanja T

Acta crystallographica. Section E, Structure reports online 20140219 Pt 3

Single crystals of Rb2Lu[Si4O10]F (dirubidium lutetium tetra-silicate fluoride) were obtained in flux-synthesis experiments in the system SiO2-Lu2O3-RbF. The compound belongs to the group of tubular chain silicates, i.e. it is based on multiple chains of condensed [SiO4] tetra-hedra forming closed columns. The periodicity of the unbranched multiple chains is four and corresponds to the length of the b axis. Adjacent columns are connected by Lu(3+) cations, which are coordinated by four oxide and ...[more]

PMID: 24764932

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Project description:Background:Monoclonal overproduction of kappa and/or lambda light chains might result in renal light chain deposition disease. Light chain associated cast nephropathy and renal AL-amyloidosis represent two further pathologies going along with monoclonal gammopathy of renal significance and multiple myeloma. While cast nephropathy often manifests with acute kidney injury, AL-amyloidosis is rather accompanied with chronic kidney disease. Methods:Urine samples were collected from 17 patients with multiple myeloma or monoclonal gammopathy. The urine sediment was stained for cast morphology by H/E and light chain immunofluorescence. Following micro-selection of casts under microscope, proteomic analysis of casts was performed by mass spectrometry. Sucrose gradient sedimentation was employed and light chain architecture examined by immunoblotting. Uromodulin was measured by ELISA in sucrose gradient fractions. Results:Urinary casts were observed of about 30 µm in diameter by H/E staining and under immunofluorescence microscopy. Casts with a diameter of 20 µm were observed as a novel variant. Proteome analysis showed that in addition to the expected light chain variants produced by the malignant clone of plasma cells, also histones such as H2B and cathepsin B were contained. Uromodulin was not detectable in urinary casts of all patients. All eleven patients with lambda light chains showed predominant dimerized light chains in the urine immunoblot. Six patients with kappa light chains presented with predominantly monomeric forms of light chains in the immunoblot. The densitometric evaluated ratio of lambda dimers vs. monomers was significantly higher (2.12 ± 0.75) when compared with the ratio of kappa dimers vs. monomers (0.64 ± 0.47), p = 0.00001. Aggregates of light chains separated in part into denser sucrose fractions. Conclusion:This work on urinary casts and light chains demonstrates that hyaline tubular casts represent a complex formation of protein-protein aggregates with histones and cathepsin B identified as novel cast components. Apart from the proteomic composition of the casts, also the formation of the light chains and aggregates is of relevance. Dimerized light chains, which are typical for lambda paraproteins, might be less dialyzable than monomeric forms and may therefore identify patients less responsive to high cut-off dialysis.

Project description:The purpose of this study was to comparatively investigate the behavior of silicate and sol-silicate coatings non-modified or modified with an organosilane on wood and on wood pre-coated with silica-mineralized primers. Adhesion strength, morphology, and water permeability and related damages were studied to evaluate the possibility of utilizing such inorganic-based coating systems for durable protection of wood without or with relatively cheap and water-borne primers. Potassium silicate and potassium methylsiliconate aqueous solutions and a colloidal silica were used for the preparation of the coatings. The white coating paints were brushed on beech wood substrates at a rate of 220 g·m-2. The coatings exhibited good coverage ability. The pull-off adhesion strength values appeared to be related to pH following a polynomial law. The adhesion strength for the silicate coatings were adequate (above 3 MPa and up to 5 MPa) for wood, whereas the values for the sol-silicates were too low for practical applications. The adhesion values were in general higher for the samples cured in a climate room (23 ± 3 °C and 75 ± 2% relative humidity) than the samples cured in the ambient atmosphere of the laboratory (23 ± 3 °C and 25 ± 5% relative humidity). The presence of microdefects (cracks, holes) was revealed in the coating layers by optical and scanning electron microscopy. The surface roughness parameters assessed by confocal scanning laser microscopy were dependent on the magnification applied for their measurement. The arithmetic average roughness Sa was between 5 µm and 10 µm at magnification 5× and between 2.5 μm and 10 µm at magnification 20×. The maximum peak-to-valley height Sz confirmed the presence of open pores emerging through the coatings. The open pores constitute free pathways for water ingress through the coatings, and could explain the high water absorption of the coatings including the methysiliconate-containing silicate coating and despite the relatively high water contact angle and low wettability exhibited by this sample. The post-application of a hydrophobizing solution containing hexadecyltrimethoxysilane and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride considerably reduced the water permeability, while application of nanosilica-containing organic primers increased the adhesion for the coatings. Silicate coatings with adhesion great enough and resistance against water damages can be generated on wood even without a primer using low silica-to-alkali ratio binders and an organosilane additive. The sol-silicate coatings appear to be applicable only with a primer. The improvement of the paint formulations to control the formation of microcracks and open pores could be useful to reduce the liquid water permeability and increase durability. Otherwise, the application of a hydrophobizing treatment can be used for this purpose.

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Rb2Lu[Si4O10]F, a tubular chain silicate.

Publications

Rb2Lu[Si4O10]F, a tubular chain silicate.

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