Structural Properties Analysis of Mg-β-TCP by X-ray Powder Diffraction with the Rietveld Refinement

The incorporation of magnesium in the synthetic apatite has been associated with the biomineralization process and osteoporosis therapy in humans and animals. β-tricalcium phosphate (β-TCP) is one of the most common bioceramics widely applied in bone cement and implants. In this work, Ca-deficient apatite (CDA) with a theoretical 0.08 Mg/(Ca+Mg) ratio was synthesized by the rapid reaction between Ca(OH)2, MgCl2.6H2O and H3PO4 at 40°C and the resultant powder calcined at 650 °C for 10h. X-ray powder diffraction analysis (XRD), in combination with the Rietveld method (Fullprof-suite), was employed for quantitative phase analysis and structural refinement. The results of XRD indicate that magnesium can substitute for calcium into a β-TCP structure inducing a reduction of the cell parameters and the compound crystallizes in the rhombohedral R3c structure, with the following unit cell constants: a = b = 10.3560 Å, c = 37.1718 Å, and cell volume V = 3452.44. The analysis indicated that the substitution of Mg2+ on the M(4) and M(5) sites were, approximately, 2.61 and 6.97 mol%, corresponding to the Ca2.72(MgIV0.07, MgV0.21)(PO4)2 stoichiometric formula and 0.09 Mg/(Ca+Mg) ratio.

The Effect of Modification Methods on the Properties of Lentinus Tuber Regium Powders

The current work considered the influence of methods of modification on the physical characteristics of Lentinus Tuber Regium (LTR) powders. The sclerotia of the LTR was pulverized to 250.0 μm and coded as native Lentinus Tuber Regium (NLTR-A). A 500.0 g of NLTR-A was submerged in 3.5 % w/v sodium hypochlorite and stirred continuously for 30.0 min. The resultant slurry was washed severally with purified water until it was neutral to litmus. The mass was dried in an oven at 60.0 °C for 2.0 h, pulverized (250.0 μm) and was noted as the modified Lentinus Tuber Regiumpowder (MLTR-B). Another 500.0 g of NLTR-A was extracted with 70.0 % v/v ethanol in a Soxhlet extractor. The resultant powder was dried at 60.0 o C for 2.0 h, micronized (250.0 μm) and coded as the modified Lentinus Tuber Regium powder (MLTR-C). Additional 500.0 g of NLTR-A was submerged in 600.0 mL of 0.5 N sodium hydroxide in a 1.0 L beaker and shaken constantly for 30.0 min. The subsequent material was splashed with purified water until the material was neutral to litmus. The mass was freed from water and introduced into 200.0 mL of 0.5 N hydrochloric acid. It was agitated for 30.0 min in a water bath at 100.0 °C. It was flooded in purified water until it was neutral to litmus. The product was dried to constant weight at 60.0 °C and pulverized (250.0 μm). The product was coded as the modified Lentinus Tuber Regium powder (MLTR-D). Generally, NLTR-A, MLTR-B, MLTR-C and MLTR-D were investigated for their organoleptic, solubility, pH, moisture studies, scanning electron microscopy (SEM), x-ray diffractometry (XRD), flow parameters and densities. The results showed that both the native and the modified powders were insoluble in water and most organic solvents. The pH of the derived powders was consistently higher. SEM and XRD revealed morphological differences in each of the derived powders, though, all the powders were non-crystalline. The respective modification methods brought about an improvement in the hydrophilic and flow properties of the modified powders when compared to the native form of LTR

Part I: Crystalline Fluorapatite-Coated Hydroxyapatite, Physical Properties

Crystalline fluorapatite-coated hydroxyapatite (FA-HA) is studied using scanning electron microscopy (SEM), X-ray diffraction (XD), energy dispersive X-ray analysis (EDX), and EDX analysis mapping (EDXM). Fluoridated HA (fluorapatite) was prepared by reacting resorbable synthetic HA (OsteoGen, Impladent, Ltd, Holliswood, NY) with 4.3% sodium fluoride (NaF) for 2 minutes. After washing and drying, the resultant powder was subjected to physical property analysis using the methods listed above. SEM showed little evidence of surface change. Changes, if any, consisted of a slightly more distinct crystalline clarity on the surface of the FA sample. XD patterns showed significant random noise dispersion of the untreated HA sample compared with the lack of noise patterns in the treated FA sample. Characteristic monetite peaks were noted in analysis of the nontreated HA control sample, whereas there was no evidence of monetite in XD analysis of the treated FA material. It was determined that the fluoridation reaction, as described, served as a purification procedure of the initial HA reagent to eliminate a more soluble monetite contaminant. Also, the reaction of fluoride ion with surface HA (whether it be from or a combination of dissolution-reapposition or isomorphic substitution) produces a more purified, crystalline FA sample that was characterized by a more characteristic and sharp XD pattern. EDX analysis of the FA sample revealed a fluoride peak at 0.70 KeV that was not seen in the nonfluoridated control. EDX mapping showed an evenly distributed needle-like crystalline-shaped particulate pattern over the entire surface of the FA sample, which was lacking in the HA control. From a variety of analytic methods (as described), it was concluded that reaction of synthetic resorbable HA with 4.3% NaF solution at neutral pH produces FA-coated HA.

The New Top-To-Bottom Method of SiAlON Precursor Preparation by Activation in a Planetary Mill with a High Acceleration

Nano-structured β-sialon precursor powders were obtained as a result of milling in a planetary mill with a high acceleration. Various mixtures of initial nitrides/oxides have been prepared as β-sialon precursor with low (0.4-1.0z) substitution and were milled in a planetary mill of acceleration 28g (TTD, Russia) with zirconia or silicon nitride balls for a various times (30-45 min). The resultant powder showed various extents of crystalline lattice deformation: smaller crystallites, dislocations, bumpy surface. The degree of lattice destruction was influenced by the milling time and grinding media, however various mixture components showed diverse susceptibility to deformation.

Preparation and Luminescence of Y2O3:Eu3+ Nanopowder

Eu3+ doped Y2O3 nanopowder was prepared by a novel complex precipitation process in which the mixture of ammonium water and ammonium hydrogen carbonate was adopted as complex precipitant. The precipitant precursor and the resultant powder were characterized by FT-IR, XRD, SEM and TEM. The resultant weakly agglomerate and spherical particles have a uniform grain size about 20nm after calcined at 850°C for 2 hours. 3mol% Eu3+ doped Y2O3 nanopowder shows an intense red luminescence at 612nm under UV excitation.

A study of twinning in YBa2Cu3O7−x by large-angle convergent-beam electron diffraction

The oxygenation of YBa2Cu3O7−x (YBCO) leads to an orthorhombic distortion of the unit cell to accommodate the extra oxygen atom. This makes the formation of twins energetically favourable with CuO4 planar unit chains running alternately along the a and b axes of the parent tetragonal structure. The geometry of this twinning is such that four possible twin variants may co-exist with the twin boundaries lying in the (110) or (110) planes of the deformed structure. The traces of these planes are not mutually perpendicular and thus the crystal is strained to allow for the mismatch. It is to the nature of this strain field that this work has been addressed.Sintered samples were prepared by crushing and dispersing the resultant powder onto a very fine Cu mesh grid. Single crystals were chemically thinned to perforation. No discernible artefacts were seen and similar results were obtained with either method.

283. The keeping qualities of milk powders: Part I. Addition of antioxidants

1. Hydroquinone is an effective antioxidant for the butter-fat of spray-dried whole-milk powder, but in a concentration equivalent to 0·5% of the weight of fat (0·12% on the weight of powder) it produces an objectionable ‘metallic’ flavour in the powder and reconstituted milk.2. Oat flour is much less efficient than hydroquinone as an antioxidant but 0·25% added to the milk, preferably before condensing, increases the resistance of the resultant powder to the development of tallowiness by the equivalent of about 4 months at normal temperatures. Raising the concentration of oat flour to 0·5% approximately doubles this increase but at the same time imparts a noticeable oat flavour to the powder.