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PubMedDate not supplied

Colloidal silicic acid for oral and topical treatment of aged skin, fragile hair and brittle nails in females.

In an open study, women with biologically aged skin and fragile or thin hair, or brittle nails were treated orally with 10 ml colloidal silicic acid (Silicol) once daily for 90 days and applied colloidal silicic acid to the face for 10 min twice daily. Of the 50 subjects treated, three withdrew from treatment after 30 days because of excessive drying of the facial skin due to topical application. In the remaining 47 subjects there was statistically significant improvement in the thickness and turgor of the skin, wrinkles and condition of the hair and nails. The number of mottles also declined, but the change was not statistically significant. Ultrasound measurements did not detect any statistically significant change in the thickness of the epidermis or elasticity of the skin, but there was a significant increase in the thickness of the dermis.

Administration, Oral↗
PubMed2006

Fabrication and characterization of polysulfone-dicalcium silicate composite films.

Polysulfone (PSU) composite films filled with Beta-dicalcium silicate (Beta-Ca(2)SiO(4)) particles are prepared by the solvent casting-evaporation method. The surface morphologies and mechanical properties of the films are determined. The bioactivity of the composite films is evaluated by soaking them in simulated body fluid (SBF) and the results show that the composites are bioactive as they induce the formation of hydroxyapatite (HAp) on the surface of the composite films. The measurement of the water contact angles suggests that the incorporation of Beta-Ca(2)SiO(4) particles into PSU matrix can improve the hydrophilicity of the composite. PSU composite films filled with modified Beta-dicalcium silicate (Beta-mCa(2)SiO(4)) particles are also prepared after Beta-Ca(2)SiO(4) particles are treated with dodecyl alcohol through surface esterification reactions. The infrared spectra of the Beta-mCa(2)SiO(4) particles before and after aging in water indicate that the surface modification is reversible. The scanning electron microscope (SEM) images (micrographs) of both composites show that the dispersion of inorganic particles in the polymer matrix improves after surface modification. The PSU-Beta-mCa(2)SiO(4) composite is still bioactive and exhibits the same water contact angle after aging in water as compared to that of the PSU-Beta-Ca(2)SiO(4) composite. All these results suggest that the incorporation of Beta-Ca(2)SiO(4) particles is a useful method to prepare composites with improved bioactivity and hydrophilicity, and the surface modification of Beta-Ca(2)SiO(4) particles can improve the dispersion while retaining the bioactivity and hydrophilicity.

Biocompatible Materials↗
PubMed2003

Catalytic properties of lipases immobilized on various mesoporous silicates.

Lipases SP525, AK, LIP, and PS were immobilized on three kinds of mesoporous silicates (FMS, PESO, and SBA) with diameters of 27 to 92 A. The amount of lipase activity adsorbed on these supports was related to the pore size of the silicate. Enantioselectivities of immobilized lipases were similar to those of free lipases, and recycling could be done in both aqueous and organic solvents.

Acetylation↗
PubMedDate not supplied

Sol-gel-derived prussian blue-silicate amperometric glucose biosensor.

A new type of inorganic biosensor is introduced. The sensor comprises glucose oxidase enzymes encapsulated in a sol-gel-derived Prussian blue-silicate hybrid network. Glucose is detected by the biocatalytic reduction of oxygen followed by catalytic reduction of hydrogen peroxide by the Prussian blue catalyst. The sol-gel silicate entails a rigid encapsulating matrix, the Prussian blue provides chemical catalysis and charge mediation from the reduction site to the supporting electrode, and the enzyme is responsible for the biocatalysis. The feasibility of a dual optical/electrochemical mode of analysis is also demonstrated.

Biosensing Techniques↗
PubMed1976

Retention and extra-articular spread of intra-articularly injected 90Y silicate.

A study was performed on the retention and distribution of intra-articularly injected colloidal 90Y silicate in 7 patients with rheumatoid arthritis (8 knees). In 5 knees retention was complete within the limits of measuring accuracy, and in the remaining 3, 82-84% was retained. No radioactivity was detected in the liver and heart areas or in the blood samples. The cumulative urine activity was less than 1.8%. In the inguinal lymph nodes, activity was detectable %0.5-2%) in only 3 cases. We conclude that 90Y silicate is a safe radioactive agent for the treatment of knee effusions, provided the limb is strictly immobilized after the injection.

Arthritis, Rheumatoid↗
PubMed2000

[Flotation and extraction spectrophotometric determination of trace silicate in water].

In HCl solution, silicate reacted with molybdate ammonium to produce silicomolibdic, then a yellow compound which was produced from the oxidation of TMB was simultaneously isolated to benzene phase by flotation and then isolated to dimethylsulfoxideformic acid by extraction. The compound gives a high absorption at 458 nm. The apparent molar absorptivity is 1.26 x 10(5) L.mol-1.cm-1. In the range of 0.02-1 mg.L-1 Si obeys Beer's law. The proposed method which combines with enrichment and measurement is simple, rapid, selective and convenient to determine silicate in water with satisfied results.

Benzidines↗
PubMed2004

[Introdoction of bioluminescence genes into silicate-dissolving bacteria strain NBT].

In this study, silicate-dissolving bacteria NBT strain was grown with 0.25% maltose as carbon source, and the rifampicin-resistance was generated by ultraviolet mutagenesis and streak naturalized to 200 microg x ml(-1). Through triparental cross, the luxAB genes were introduced into NBT-R200 at the help of pRK2013. The luminescence activity of the hybrid strain was tested, which indicated that all colonies had a high luminescence activity and kanamycin-, tetracyctine-and rifampicin-resistance. The NBT-R200 cells prepared from initial logarithmic growth phage were more likely to be sensitive to foreign DNA, and the maximum translocation frequency was up to 6.70 x 10(-5). In addition, the optimal mating ratio was 1:1:1. The potassium release ability from feldspar and the luminescence of luxAB genes marked silicate-dissolving bacteria RL85 strain were stable, and hence, the RL85 was available to rhizosphere microecology researches.

Bacteria↗
PubMedDate not supplied

[Conservative motif CMLD in silicic acid transport proteins of diatom algae].

Sequencing of fragments of genes coding for silicic acid transport (SIT) proteins of diatoms of evolutionary distant classes (centric Chaetoceros muelleri Lemmermann, pennate araphid Synedra acus Kützing, pennate raphid Phaeodactylum tricornutum Bohlin, and pennate with keeled raphe system Cylindrotheca fusiformis Reimann et Lewin), revealed the presence in these proteins of a conservative amino acid motif CMLD. Hydropathy profiles suggest that CMLD occupies a position between two transmembrane strands which do not contain lysine and arginine residues. The two strands are good candidates for the role of the channel along which transport of silicic acid occurs. CMLD is a rare motif. Diatoms are known to need Zn2+ for the incorporation of silica. Presumably, CMLD is the site of Zn2+ binding of SITs. We found that the growth of diatoms is inhibited by a negatively charged alkylating reagent 5-(2-iodoacetamidoethyl)aminonaphtalene-1-sulfonic acid which cannot penetrate through the cell membrane. Cysteine of CMLD can be a target of this reagent. Synthetic peptide NCMLDY forms a complex with Zn2+, as revealed by the fact that the ion considerably reduces the rate of alkylation of the peptide.

Amino Acid Motifs↗
PubMed2006

[Preparation and properties of calcium silicate-phosphate composite bone cements].

In this paper, alpha-tricalcium phosphate (alpha-TCP) and tetracalcium phosphate (TTCP) respectively were chosen as basic compositions of phosphate bone cements. Other auxiliary materials such as hydroxyapatite (HAP), dicalcium phosphate dihydrate (DCPD), calcium carbonate (CaCO3), calcium oxide (CaO) and amorphous calcium silicate (CaSiO3) were added in the cements. Six kinds of composite bone cements were decided with 1.50 as their Ca/P ratio. Then the primary properties of them were studied. Ringer's simulated body fluid (SBF) tests were carried out for the samples. The changes of pH value in SBF and the compressive strength of the samples with the immersion time were studied. The results showed: the mixing liquid 0.25 M K2HPO4/KH2PO4 and amorphous CaSiO3 were effective for accelerating the setting of the cements; the initial setting time (It) was about 4-5.5 min and the final setting time (Ft) was about 18-19. 5 min. Amorphous calcium silicate can increase the compressive strength of the bone cements remarkably; the compressive strength of the alpha-TCP bone cement with the addition of suitable amount amorphous CaSiO3 reached 45.3 MPa after immersion in SBF for 14 days.

Bone Cements↗
PubMed1977

[Serum-treatment in the rubella hi-test by menas of silicic acid (author's transl)].

The serum treatment for the removal of nonspecific inhibitors in the Rubella HI-test with silicic acid was investigated by means of isolated lipoproteins and after a micromethod by means of Sindbis-virus. Reduction of the three classes of lipoproteins after treatment with silicic acid was good. In the Sindbis HI-test only 2% of the sera showed low titers after treatment. The method proved to be a reliable tool as removal of unspecific inhibitory activity is concerned.

Female↗
PubMedDate not supplied

Effect of silicic acid on surface potential of erythrocytes.

A potential-generating effect of ortho-silicic acid on the surface potentials of erythrocyte membranes was demonstrated by a potentiometric method using platinum electrodes. With concentration rising from 10(-7) to 10(-4) the silicic acid reduced potential of washed erythrocytes which reached the final concentration a value about 36 mV. Higher concentrations of acid caused haemolysis.

Adult↗
PubMed1990

Silicic acid HPLC of cardiolipin, mono- and dilysocardiolipin, and several of their chemical derivatives.

A silicic acid HPLC system in hexane-2-propanol-1 mM H3PO4 50:50:3.5 (v/v/v) is described for the analysis and/or purification of cardiolipin (CL), monolysocardiolipin (MLCL), dilysocardiolipin (DLCL), and several of their chemical derivatives. Derivatives that have been successfully analyzed include CL that is acetylated, succinylated, or tetrahydropyranylated at the 2-hydroxyl; MLCL acetylated at the 2 and 2'-hydroxyls; DLCL acetylated at the 2-hydroxyl and both 2'-hydroxyls; and MLCL tetrahydropyranylated at only the 2-hydroxyl. Water can replace 1 mM H3PO4 in the eluting solvent, but prior conditioning of the silicic acid column with the phosphoric acid solvent is necessary for acceptable chromatography. The most significant factor affecting the elution times of these compounds is the percentage of aqueous component, i.e., water or 1 mM H3PO4.

Cardiolipins↗
PubMed1979

[Determination of free crystalline silica in the dust containing silicates].

The content of free crystalline silica in dusts containing silicates was investigated using Polezajew's method, the HBF4 method and X-ray diffraction. Polezajew's method was found to give highly increased results (133.4% on the average), and with 5% of quartz in mixture with kaolin--252%. Solution of silicates, when heated, in fluoroboric acid considerably reduces the error of determination. The mean value of SiO2 recovery in mixtures of quartz with kaolin is 102.9% and with 5% of quartz--116. This method is highly precise. The results of determination of crystalline silica content in some mineral raw materials used in ceramic industry approximated the results obtained using X-ray diffraction.

Crystallization↗
PubMed1996

Silicate and metal dust in lungs of Greyhounds.

OBJECTIVES: To determine whether the amount of opaque dust in lung specimens increases with age, the composition of that dust, and whether the composition is similar for Greyhounds and pet dogs. DESIGN: Quantification of lung particulate dust burdens. ANIMALS: 192 Greyhounds and 5 pet dogs. PROCEDURE: Lung specimens of 192 Greyhounds and 5 pet dogs were examined for dust accumulation, using light microscopy. Lung specimens from Greyhounds and the 5 pet dogs were analyzed, using scanning electron microscopy and energy dispersive x-ray spectroscopy to quantify the lung burden of inorganic particles. RESULTS: Lung dust burden increased linearly with age. Pulmonary dust was composed of aluminum silicates, silica, and 18 metals. Silicate and metal particulate burdens were higher in Greyhounds than in the pet dogs. The 3 most common metals were iron, titanium, and chromium. CONCLUSIONS AND CLINICAL RELEVANCE: Amount of opaque dust increased with age. The higher pulmonary dust burden in Greyhounds than in pet dogs suggests that environmental exposure is important.

Animals↗
PubMed1999

High precision delta(17)O isotope measurements of oxygen from silicates and other oxides: method and applications.

The use of infrared laser-assisted fluorination to release oxygen from milligram quantities of silicates or other oxide mineral grains is a well-established technique. However, relatively few studies have reported the optimisation of this procedure for oxygen-17 isotope measurements. We describe here details of an analytical system using infrared (10 µm) laser-assisted fluorination, in conjunction with a dual inlet mass spectrometer of high resolving power ( approximately 250) to provide (17)O and (18)O oxygen isotope measurements from 0.5-2 mg of silicates or other oxide mineral grains. Respective precisions (1) of typically 0.08 and 0.04 per thousand are obtained for the complete analytical procedure. Departures from the mass-dependent oxygen isotope fractionation line are quantified by Delta(17)O; our precision (1) of such measurements on individual samples is shown to be +/-0.024 per thousand. In turn, this permits the offset between parallel, mass-dependent fractionation lines to be characterised to substantially greater precision than has been possible hitherto. Application of this system to investigate the (17)O versus (18)O relationship for numerous terrestrial whole-rock and mineral samples, of diverse geological origins and age, indicates that the complete data set may be described by a single, mass-dependent fractionation line of slope 0.5244+/- 0.00038 (standard error). Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Silicate entrapped columns--new columns designed for capillary electrochromatography.

Designed especially for capillary electrochromatography (CEC), silicate-entrapped columns are made by trapping particles of chromatographic packing material in a network of silica. Once entrapped, the capillary no longer requires frits. This renders a more homogeneous and stable packed bed. Accidental breakage of the fragile frits is not an issue with these robust columns. Columns packed with reverse-phase material subjected to silicate entrapment demonstrated faster separations of retained analytes and increased efficiencies compared with nonentrapped columns. The method was also used to prepare chiral CEC columns by entrapping a molecular imprinted polymeric (MIP) packing having minimal surface charge density, thus being unable alone to support sufficient electroosmotic flow for CEC.

Chromatography, Liquid↗
PubMed2006

The leading role of association in framework modification of highly siliceous zeolites with adsorbed methylamine.

Affinity index (AT value), adsorption heat, X-ray diffraction (XRD), and 13C and 29Si magic-angle spinning (MAS) NMR, FTIR, and Raman spectroscopies were used to study the interaction of highly siliceous MFI-, FAU-, and FER-type zeolites with adsorbed methylamine (MA). Compared with the data for methanol, the much higher AT values and adsorption heats, and significant changes in XRD patterns, 29Si MAS NMR spectra, and FTIR spectra for the zeolites after adsorption of MA, revealed a strong hydrogen-bonding interaction between the perfect framework of the zeolites and the adsorbed MAs. This interaction results from the fact that the H atom of the amine group attacks the [Si-O] framework to form a Si-OHN bond, which leads to the appearance of Si-N bonds in the zeolites at 323 K. Therefore, the zeolite framework can be modified with MA under mild conditions. The highly siliceous MFI zeolite and the H-ZSM-5 zeolite with SiO2/Al2O3=31:1 were modified with MA and investigated by temperature-programmed desorption of CO2. The modified zeolites exhibited greatly enhanced basic properties in comparison with those of the raw materials. The influence of defects in the zeolite on the adsorption and the interaction with MA is discussed.

Journal Article↗
PubMed2003

Physical and chemical analysis of the siliceous skeletons in six sponges of two groups (demospongiae and hexactinellida).

The siliceous skeletons of six hexactinellids and demosponges were compared using a series of physical and chemical tests. The sponges were two hermit-crab sponges (Class Demospongiae, family Suberitidae), one from Scotland, Suberites domuncula, and the other, Pseudospongosorites suberitoides, from the Gulf of Mexico, and four hexactinellids, Hyalonema sp., Euplectella aspergillum, Rhabdocalyptus dawsoni, and Aphrocallistes vastus. The operating hypothesis was that differences in the amorphous hydrated silica skeletons in Demosponges and Hexactinellids might prove taxonomically useful. Physical properties studied included SEM, glass density, glass transition temperature (Tg), TG/DTA to determine water content, and FTIR spectra. Chemical determinations were made using energy dispersive X-ray fluorescence (EDXRF). Spicular skeletal material is deposited in concentric layers around the axial canal. With the exception of differences at several bands in the IR spectra, the siliceous skeletons in demosponges and hexactinellids are largely indistinguishable. Density was similar in all sponges (range 2.03-2.13 g/cc) and similar to the density of opal (SiO2 x 1.5H2O) (mean = 2.09 g/cc). IR spectra were similar, with prominent absorption bands at 460-470, 800, and 1,090-1,100 cm(-1) (due to different vibrational modes of Si-O-Si linkages) and at 1,650 and 3,450-3,560 cm(-1) (due to water). The skeletons of all six showed similar spectra to that of silica gel both before and after heating to 1,200 degrees C. Water comprised 10-14% of the skeleton by weight, slightly higher in the demosponges. Average spicule chemical composition was 85.2% SiO2, 12.3% water, and 2.5% other elements (mainly S, Al, K, Ca, and Na). The percent amounts of Si did not differ significantly between the demosponges and the hexactinellids.

Animals↗