The solid solutions of rebulite and jankovićite in the phase system Tl2S-As2S3-Sb2S3

Syntheses along the Tl₅(As,Sb)₁₃S₂₂ compositional line in the Tl₂S-As₂S₃-Sb₂S₃ phase system showed that the compositional range of rebulite extends from  Tl₅As_9.5Sb_3.5S₂₂ to Tl₅As_7.75Sb_5.25S₂₂. The Sb-rich end-member is in equilibrium with jankovićite of ideal composition Tl₅Sb_7.5As_5.5S₂₂. It is considered to be the As-rich end-member of the jankovićite solid solution. The crystal structure analyses of crystals from the As and Sb end-members of rebulite show that the Sb/As substitution is present in Sb3, Sb4, Sb5, As1 and As2 structural sites. Of them, Sb3 is always Sb dominated whereas other four vary from As- to Sb-dominated over the range of the solid solution. The change of the structural topology from jankovićite to rebulite, the closely related but not identical structures, is explained through necessity to accommodate the smaller volumes of the As coordination polyhedra and is accomplished through unit-cell twinning over the periodic (001)_reb twin boundaries. The As end-member of the rebulite solid solution is in equilibrium with the phase of Tl_2.4Sb_0.68As_7.18S₁₃ ideal composition, interpreted as imhofite.

Application of the ellipsoid modeling of the average shape of nanosized crystallites in powder diffraction

Anisotropic broadening correction in X-ray powder diffraction by an ellipsoidal formula is applied on samples with nanosized crystals. Two cases of minerals with largely anisotropic crystallite shapes are presented. The properly applied formalism not only improves the fitting of the theoretical and observed diffraction diagrams but also gives direct information about realistic crystallite shapes and sizes. The approach is demonstrated using the Rietveld refinement programTOPASand it is easily adaptable to other similar software.

Comparison between beryllium and diamond-backing plates in diamond-anvil cells: application to single-crystal x-ray diffraction high-pressure data

A direct comparison between two complete intensity datasets, collected on the same sample loaded in two identical diamond-anvil pressure cells equipped, respectively, with beryllium and diamond-backing plates was performed. The results clearly demonstrate that the use of diamond-backing plates significantly improves the quality of crystal structure data. There is a decrease in the internal R factor for averaging, structure refinement agreement factors, and in the errors and uncertainties of the atomic coordinates, atomic displacement parameters, and individual bond lengths.

Time-response relationship of nano and micro particle induced lung inflammation. Quartz as reference compound

An increasing number of engineered particles, including nanoparticles, are being manufactured, increasing the need for simple low-dose toxicological screening methods. This study aimed to investigate the kinetics of biomarkers related to acute and sub-chronic particle-induced lung inflammation of quartz. Mice were intratracheal instilled with 50 µg of microsized or nanosized quartz. Acute inflammation was assessed 1, 2, 4, 8, 16 or 48 hours post exposure, whereas sub-chronic inflammation was investigated 3 months after exposure. Markers of acute inflammation in the bronchoalveolar lavage fluid (BALF) were neutrophils (PMN), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, macrophage inflammatory protein-2 (MIP-2), keratinocyte derived chemokine (KC) and total protein, which were all close to maximum 16 hours post instillation. No major differences were seen in the time-response profiles of nano- and micro-sized particles. The potency of the two samples cannot be compared; during the milling process, a substantial part of the quartz was converted to amorphous silica and contaminated with corundum. For screening, BALF PMN, either TNF-α or IL-1β at 16 hours post instillation may be useful. At 3 months post instillation, KC, PMN and macrophages were elevated. Histology showed no interstitial inflammation three months post instillation. For screening of sub-chronic effects, KC, PMN, macrophages and histopathology is considered sufficient.

Identification of green rust in groundwater

Green rust, a family of Fe(II), Fe(III) layered double hydroxides, is believed to be present in environments close to the Fe(II)/ Fe(III) transition zone. Attempts to identify members of this family in nature have proven difficult because the material is oxidized after only a few minutes exposure to air. In this paper, we present a sampling method for capturing green rust so it is not oxidized. We then we used the method to identify the compound in a groundwater sample taken below the water table from fractures in granite. X-ray diffraction patterns were weak, but clearly identical to those of synthetic GR(CO3), the green rustfamily memberwhere carbonate and water occupy the interlayer between the iron-hydroxide layers. The method was then tested on samples taken from an artesian well and a deep underground experimental station, both within the Fe(II)/ Fe(III) redox zone. In both cases, GR(CO3), could be identified. Currently, transport models for predicting the behavior of contaminants in groundwater do not include parameters for green rust This work demonstrates they should.

Identification of monoclinic calcium pyrophosphate dihydrate and hydroxyapatite in human sclera using Raman microspectroscopy

Raman microspectroscopy was first used to determine the composition of a calcified plaque located at the pterygium-excision site of a 51-year-old female patient's left nasal sclera after surgery. It was unexpectedly found that the Raman spectrum of the calcified sample at 1149, 1108, 1049, 756, 517, 376 and 352/cm was similar to the Raman spectrum of monoclinic form of calcium pyrophosphate dihydrate (CPPD) crystal, but differed from the Raman spectrum of triclinic form of CPPD. An additional peak at 958/cm was also observed in the Raman spectrum of the calcified plaque, which was identical to the characteristic peak at 958/cm of hydroxyapatite (HA). This is the first study to report the spectral biodiagnosis of both monoclinic CPPD and HA co-deposited in the calcified plaque of a patient with sclera dystrophic calcification using Raman microspectroscopy.