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At least 685 records · Page 38Linked to original sources
PubMed2004

Synthesis of nanophase hydroxyapatite by a Serratia sp. from waste-water containing inorganic phosphate.

Synthesis of nanophase hydroxyapatite (HA) on a bacterial surface was achieved at the expense of CaCl2 and inorganic phosphate (Pi). After initial nucleation, calcium was precipitated on and around the cells as calcium phosphate at the expense of inorganic phosphate in the challenge solution, with no precipitation in cell-free controls. HA was also biomanufactured using inorganic phosphate ions scavenged from a phosphate-containing waste-water. With additional Ca2+, the concentration of phosphate was decreased from 0.27 (approximately 25 ppm) to approximately 0.02 m (approximately 2 ppm) in the waste-water. Crystals of calcium phosphate manufactured by the cells were located by scanning electron microscopy (SEM) and identified as HA by X-ray powder diffraction, with an average crystal size calculated as approximately 25 nm. Possible application of bioHA as a biomaterial and implications for one-step 'waste-into product' are discussed.

Biodegradation, Environmental↗
PubMed2005

Mercury tolerance of thermophilic Bacillus sp. and Ureibacillus sp.

Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately thermophilic mercury resistant bacteria were selected by growth at 62 degrees C on Luria agar containing HgCl(2). Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl(2) were 80 microg/ml and 30 microg/ml for these isolates, respectively, compared to 10 microg/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 microg/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H(2)S was detected in the headspace of cultures in the absence or presence of Hg(2+), and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have potential for decontamination of solutions containing Hg(2+) without production of toxic volatile H(2)S.

Bacillus↗
PubMed2004

Microwave accelerated synthesis of nanosized calcium deficient hydroxyapatite.

Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca(10-x)(HPO4)x(PO4)(6-x)(OH)(2-x)) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA has the characteristic HPO4(2-) vibration band at 875 cm(-1) in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (beta-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600 degrees C.

Calcium↗
PubMed2006

Sonochemical synthesis of calcium phosphate powders.

beta-tricalcium phosphate (beta-TCP) and biphasic calcium phosphate powders (BCP), consisting of hydroxyapatite (HA) and beta-TCP, were synthesized by thermal decomposition of precursor powders obtained from neutralization method. The precursor powders with a Ca/P molar ratio of 1.5 were prepared by adding an orthophosphoric acid (H(3)PO(4)) solution to an aqueous suspension containing calcium hydroxide (Ca(OH)(2)). Mixing was carried out by vigorous stirring and under sonochemical irradiation at 50 kHz, respectively. Glycerol and D-glucose were added to evaluate their influence on the precipitation of the resulting calcium phosphate powders. After calcination at 1000 degrees C for 3 h BCP nanopowders of various HA/beta-TCP ratio were obtained.

Biocompatible Materials↗
PubMed2006

Design and evaluation of celecoxib porous particles using melt sonocrystallization.

PURPOSE: The purpose of the article was to study melt sonocrystallization (MSC) for a drug forming a viscous melt when processed below its glass transition temperature. METHODS: A molten mass of drug was poured in a vessel containing deionized water, maintained at 40 degrees C using cryostatic bath, and sonicated for 1 min using probe ultrasonicator at an amplitude of 80% and a cycle of 0.8 per second. The product obtained after solidification of dispersed droplets was separated by filtration and dried at room temperature. MSC celecoxib was characterized by solubility determination, scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction, and stability study. RESULTS: The MSC technique was designed for celecoxib, which undergoes fast solidification. The particles obtained by MSC were porous, irregular in shape, and amorphous in nature. An increase in the apparent solubility was observed for the MSC particles. These amorphous particles also exhibited a higher stability in the amorphous state as compared with particles obtained by melt quenching. CONCLUSIONS: The reported MSC technique for celecoxib demonstrates advantages over other approaches and can be exploited in area of particle design for the amorphization of drugs.

Calorimetry, Differential Scanning↗
PubMed2006

General trends in the desolvation behavior of calcium salts.

PURPOSE: This paper is concerned with the solid-state characterization of dehydrated calcium salts as well as the effect of dehydration on the physical properties of these salts. METHODS: The salts were analyzed by X-ray powder diffraction (XRPD), single crystal X-ray and polarized light microscopy (PLM). RESULTS: Our research was able to identify three general behaviors of the desolvation of calcium salts of carboxylic acids. Upon desolvation, ethanolate and pentahydrate calcium indomethacin (CaIndo and CaInd2, respectively) stayed crystalline, fenoprofen calcium (CaFEN), calcium ketoprofen (CaKTN), calcium salicylate (CaSAL), calcium mefenamate (CaMEF) and calcium tolfenamate (CaTOLF) became mesophases, while calcium diflunisal became partially crystalline. On the other hand, the solubility studies of CaFEN, CaKTN and CaSAL showed that all dehydrated calcium salts had higher solubility than their crystalline counterparts and amorphous CaKTN had higher solubility than mesomorphous CaKTN. CONCLUSIONS: Several factors influence the desolvation behavior of calcium salts. We believe the flexibility of the benzene rings in CaKTN, CaFEN, CaMEF and CaTOLF was important for these products to become mesomorphous when they loose their crystalline water; meanwhile, CaDIF where the two benzene rings are coplanar remained crystalline when heated. Additionally, the existence of water channels and the hydrogen bonding networks in the crystals is hypothesized to play an important role in the desolvation behavior of these materials.

Calcium↗
PubMed2006

Targeted high lung concentrations of itraconazole using nebulized dispersions in a murine model.

PURPOSE: The purpose of this study was to investigate the delivery of itraconazole (ITZ) particles to a murine lung model by nebulization. METHODS: Three ITZ formulations were prepared and characterized in the dry state using contact angle, dissolution, X-ray powder diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller surface area analysis. Aerodynamic particle size distributions and lung deposition studies in 14 outbred male ICR mice were performed using aqueous dispersions of all the formulations. A separate dosing uniformity study was also performed to qualify use of the chamber. RESULTS: All formulations had an aggregated particle size of approximately 30 microm in diameter. Two formulations showed that 80% of the drug dissolved in less than 5 min. The remaining ITZ formulation had a slower dissolution and the lowest total emitted dose from the nebulizer used. High concentrations of ITZ were shown to be present in the mouse lung during the lung deposition study, up to 16.8 +/- 0.13 microg/g (+/- SE) were achieved. Concentrations of up to 0.76 +/- 0.03 microg/g (+/- SE) could be maintained from the single nebulized dose for at least 24 h. CONCLUSION: An effective method of targeted delivery of ITZ to the deep lung is presented that may be useful for the treatment and prevention of acute fungal infections.

Administration, Inhalation↗
PubMed1988

Interaction of D-glucose with alkaline-earth metal ions. Synthesis, spectroscopic, and structural characterization of Mg(II)- and Ca(II)-D-glucose adducts and the effect of metal-ion binding on anomeric configuration of the sugar.

The interaction of D-glucose with the hydrated alkaline-earth metal halides has been studied in solution, and adducts of the type Mg(D-glucose)X2.4 H2O, Ca(D-glucose)X2.4 H2O, and Ca(D-glucose)2X2.4 H2O, where X = Cl- and Br-, have been isolated, and characterized by means of F.t.-i.r. and 1H-n.m.r. spectroscopy, X-ray powder diffraction, and molar conductivity measurements. Spectroscopic and other evidence suggested that the Mg(II) ion in the Mg(D-glucose)X2.4 H2O adducts six-coordinate, binding to a D-glucose molecule (possibly via O-1 and O-2 atoms) and to four H2O molecules, whereas, in the corresponding 1:1 Ca-D-glucose adduct, the Ca(II) ion is possibly seven-coordinate, binding to a sugar moiety (through the O-1, O-2, and other sugar donor atoms) and to four H2O molecules. In 1:2 Ca(D-glucose)2X2.4 H2O, the calcium ion may be eight-coordinate, binding to two D-glucose molecules (possibly via the O-1 and O-2 atoms of each sugar moiety) and to four H2O molecules. The strong, sugar H-bonding network is rearranged upon D-glucose adduct-formation, and the alpha-anomeric configuration is favored by these metal cation coordinations.

Calcium↗
PubMed1993

Inclusion complexes of cyclomaltoheptaose (beta-cyclodextrin) and its methylated derivatives with the main components of the pheromone of the olive fruit fly.

The inclusion complexes of cyclomaltoheptaose (beta CD) and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose (TM-beta CD) with the four major components of the pheromone of the olive fruit fly (Dacus oleae), namely 1,7-dioxaspiro[5.5]undecane, (-)-alpha-pinene, nonanal, and ethyl dodecanoate, and the complex of heptakis(2,6-di-O-methyl)cyclomaltoheptaose (DM-beta CD) with 1,7-dioxaspiro[5.5]undecane were studied. The complexes were characterised in the solid state by differential scanning calorimetry and X-ray powder diffraction. In aqueous solution, the structure of the complexes was investigated by 1H NMR spectroscopy. In solution, 1,7-dioxaspiro[5.5]undecane, (-)-alpha-pinene, and nonanal enter the cavity of the cyclo-oligosaccharides. Association constants for some of these complexes were also measured. The complexes of ethyl dodecanoate did not provide evidence of their structure in solution. This was attributed to the existence of negligible amounts of these complexes in water due to the combined effects of low solubility and low association constant.

Aldehydes↗
PubMed1983

Physico-chemical characterization of atmospheric trace metal emissions from a primary zinc-lead smelter.

Emissions from the stacks of a major primary zinc--lead smelter were characterised using X-ray powder diffraction spectrometry (XRD). The following chemical phases were identified: PbSO4, PbO X PbSO4, PbO, PbS, PbO, ZnO, alpha-ZnS, CdO. A complementary environmental investigation revealed that, within the works boundary, the airborne metals might be associated mainly with the fugitive blowage of coarse particles containing primary ore minerals. However, such fugitive emissions were found to be of low significance in the local environment outside the works perimeter, where fine particle emissions from the stacks of the smelter were the predominant source of airborne cadmium, lead and zinc.

Air Pollutants↗
PubMed1994

Analysis of nickel refinery dusts.

After characterization of bulk samples by inductively coupled plasma emission spectroscopic (ICP-ES) quantitative analysis and X-ray powder diffraction studies, single particle techniques using quantitative image analysis, scanning electron microscopy--energy dispersive analysis by X-ray, and finally laser beam ionization mass spectrometry analysis (LIMA) for surface analysis have been applied to historical nickel refinery dust samples from the nickel refining plant at Clydach in Wales. There were two historical samples of processed material from 1920 and 1929. These samples had a remarkably small particle size range, mean 3 microns and range, 0.75-24 microns. The most significant difference in elemental composition was the presence of 10% arsenic in the 1920 sample compared with 1% in the 1929 sample. The X-ray spectra revealed the presence of NiO in both. However, surprisingly, CuO was identified only in the 1929 sample. Of particular interest was the presence of a component, in the 1920 sample only, identified as the mineral orcelite, a copper-iron-nickel-arsenide-sulphide mineral, predominantly, Ni5-XAs2. Using the LIMA technique, it was found that in both samples, arsenic and arsenic derivative peaks are prominent, indicating the surface availability of arsenic compounds.

Arsenic↗
PubMed1989

Calcium environment in encrusting deposits from urinary catheters investigated by interpretation of EXAFS spectra.

Extended x-ray absorption fine structure (EXAFS) spectra were recorded, above the K absorption edge of Ca, from 10 encrusted urinary (Foley) catheters obtained from 10 different patients. The presence of poorly crystalline apatite was demonstrated in all the deposits, even though this phase could not be detected in the x-ray powder diffraction patterns of most samples because of the obscuring effect of struvite, which was also present. Furthermore, the EXAFS spectra could be interpreted to yield quantitative information on the average short-range structure surrounding the Ca2+ ions in the poorly crystalline apatite.

Calcium↗
PubMed1989

Synthesis and characterization of new chromium(III), vanadium(IV), and titanium(III) complexes with biologically active isonicotinic acid hydrazide.

New complexes of the type [Cr(INH)2Cl2]Cl.2H2O, VO(INH)2Cl2 and TiO(INH)2Cl, where INH = isonicotinic acid hydrazide, have been prepared. The complexes were characterized by infrared and UV-vis spectroscopy, proton nuclear magnetic resonance (NMR) and elemental analyses, molar conductivity and x-ray powder diffraction measurements. For the Cr(III)-complex, the ligand was coordinated through its carbonyl group and amino nitrogen atom; for V(IV)-complex and Ti(III)-complex, the ligand was coordinated through its carbonyl oxygen and heterocyclic nitrogen, respectively. Octahedral geometry has been proposed for all the complexes. The complexes of Cr(III) and Ti(III) showed significant tuberculostatic activity.

Antitubercular Agents↗
PubMed1993

Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland.

Physical, chemical, and mineralogical investigations of mineral concretions found in the human pineal gland were performed by means of optical microscopy and modern techniques of analytical electron microscopy and x-ray powder diffraction (OM,SEM + EDS,TEM + EDS,XRD). The mineral concretions were found to be nano-crystalline carbonate-hydroxyapatite with a mean Ca/P molar ratio equal to 1.65, very close to the theoretical value of 1.67. TEM and XRD showed that this is the only inorganic phase present in the concretions without the presence of amorphous phosphate as precursor. SEM and EDS, performed on cross-sectioned samples, showed a concentric layered distribution of the inorganic phase permeated by organic matter, within the concretions, with a slight increasing of the Ca/P molar ratio in their internal part.

Aged↗
PubMed1995

Unsymmetrical borole complexes as biocides: synthetic, structural and biological aspects.

Triisopropoxyborane on treatment with catechol in equimolar ratio in excess of benzene affords the formation of 2-isopropoxybenzo-1,3-dioxa-2-borole [OC6H4OB(OPri)]. The interaction of [OC6H4OB(OPri)] with benzothiazolines, prepared by the condensation of [1-(2-thienyl)ethanone], [1-(2-pyridinyl)ethanone], [1-(2-furanyl)ethanone], and [1-(2-naphthenyl)ethanone] with 2-mercaptoaniline, yields complexes that have B--O, B--S, and B<--N bonds. The unsymmetrical borole complexes were subjected to microestimations and spectral analyses comprised of UV, IR, proton-1, boron-11, and carbon-13 nuclear magnetic resonance studies. The spectral studies point to a tetracoordinated environment around boron because the stereochemically active lone pair is also included in the coordination sphere. X-ray powder diffraction of a representative complex also has been carried out. In the quest for better fungicides and bactericides, studies were conducted to assess the growth-inhibiting potential of the synthesized complexes along with the ligands against various fungal and bacterial strains. The studies demonstrate that the concentrations reach levels that are sufficient to inhibit and kill the pathogens. Furthermore, the results achieved from biological activity also have been compared with the conventional fungicide, Bavistin, and conventional bactericide, Streptomycin.

Anti-Bacterial Agents↗
PubMed1995

Comparison of polysaccharide iron complexes used as iron supplements.

An oral hematinic marketed as "water soluble polysaccharide iron complex" (Vitaline Formulas) has been characterized using x-ray powder diffraction and Mössbauer spectroscopy. Another polysaccharide iron complex marketed as Niferex (Central Pharmaceuticals) has been previously studied by us and found to have a core similar to ferrihydrite, but with some long-range order of the mineral akaganéite, beta-FeOOH. The latter is seen in other ferric carbohydrate complexes synthesized by the hydrolysis of FeCl3. This commercial product, however, is very different and has a mixture of iron components including hematite (alpha-Fe2O3) magnetite (Fe3O4), goethite (alpha-FeOOH), iron metal, and a ferrous salt.

Hematinics↗
PubMed1996

Protein interactions with bivalent tin. 1. Hydrolysis and complexation of tin(II) ion with glycine.

The complexation between tin(II) ion and glycine was studied in 0.15 mol/dm3 NaCl medium at 310 K using potentiometric glass electrode titrations. In the pH range 1.1-4.5 and concentration range of the tin(II) between 0.2 and 5.0 mmol/dm3, with variable glycine-to-tin molar ratio up to 10:1, the experimental data were explained by the formation of the following complexes and their overall stability constants: log(beta +/- sigma): Sn(HGly)+, (12.78 +/- 0.08); Sn(Gly)+, (10.02 +/- 0.07); Sn(OH)Gly, (7.34 +/- 0.03), as well as the pure hydrolytic complex Sn4(OH)2+(6), whose stability constant was determined in separate experiments and found to be -4.30 +/- 0.08, under the same experimental conditions as for complexation study. The precipitate formed in tin(II)-glycine system at pH ca. 5.0 was characterized by chemical and TG analysis, I. R. spectra, X-ray powder diffraction, and electron scanning microscopy measurements. It has been shown that the precipitate has the composition Sn(OH)Gly and crystallizes in a tetragonal system with unit cell dimensions a = b = 1.584 nm, c = 0.597 nm. The mechanism of the complex formation in solution is discussed.

Cations, Divalent↗