The crystal structure of munakataite, Pb_2Cu_2(Se^(4+)O_3)(SO_4)(OH)_4, from Otto Mountain, San Bernardino County, California, USA

Munakataite, Pb_2Cu_2(Se^(4+)O_3)(SO_4)(OH)_4, has been found in association with a variety of rare secondary Te minerals at Otto Mountain, San Bernardino County, California, USA. It is very rare and occurs as subparallel bundles of blue needles up to 1 mm long. Electron microprobe analyses provided the empirical formula Pb_(1.96)Cu_(1.60)[(Se^(4+)_(0.89)S_(0.11)_(∑1)O_3](SO_4)[(OH)_(3.34)(H_2O)_(0.66)]_(∑4). Munakataite is monoclinic, space group P2_1/m, with cell parameters a = 9.8023(26), b = 5.6751(14), c = 9.2811(25) Å , β = 102.443(6), V = 504.2(2) Å^3 and Z = 2. The crystal structure, solved by direct methods and refined to R_1 = 0.0308 for 544 F_o > 4σF reflections, consists of Jahn-Teller-distorted Cu^(2+)O_6 square bipyramids, which form chains along b by sharing trans edges across their square planes. The chains are decorated by SO_4 tetrahedra and Se^4+O_3 pyramids, which bond to apical corners of adjacent bipyramids. The chains are linked to one another via bonds to two different PbO_9 polyhedra, only one of which exhibits one-sided coordination typical of Pb^(2+) with a stereochemically active 6s^2 lone-electron-pair. Munakataite is isostructural with schmiederite and the structure is closely related to that of linarite

Anorpiment, As_(2)S_(3), the triclinic dimorph of orpiment

The new mineral anorpiment, As_(2)S_(3), the triclinic dimorph of orpiment, has space group P1 and cell parameters a = 5.7577(2), b = 8.7169(3), c = 10.2682(7) Å, α = 78.152(7), β = 75.817(7), γ = 89.861(6)º, V = 488.38(4) Å^3 and Z = 4. It occurs at the Palomo mine, Castrovirreyna Province, Huancavelica Department, Peru. It is a low-temperature hydrothermal mineral associated with dufrénoysite, muscovite, orpiment, pyrite and realgar. It occurs in drusy crusts of wedge-shaped, transparent, greenish yellow crystals. The streak is yellow. The lustre is resinous on crystal faces, but pearly on cleavage surfaces. The Mohs hardness is about 1½. The mineral is sectile with an irregular fracture and one perfect and easy cleavage on {001}. The measured and calculated densities are 3.33 and 3.321 g cm^(-3), respectively. All indices of refraction are greater than 2. The mineral is optically biaxial (—) with 2V = 35-40º and no observed dispersion. The acute bisectrix (X) is approximately perpendicular to the {001} cleavage. Electron microprobe analyses yielded the averages and ranges in wt.%: As 58.21 (57.74-59.03), S 38.72 (38.33-39.00), total 96.94 (96.07-97.75), providing the empirical formula (based on 5 atoms) As_(1.96)S_(3.04). The strongest powder X-ray diffraction lines are [d (hkl) I] 4.867(002) 97, 4.519 (110,111) 77, 3.702 (111) 46, 3.609 (022,112) 82, 2.880 (201,022,121,023) 75, 2.552 (113,131,132) 100, 2.469 (114,130,131) 96. The structure of anorpiment [R_1 = 0.021 for 1484 reflections with F_o > 4σ(F)] consists of layers of covalently bonded As and S atoms. Each S atom bonds to two As atoms at As-S-As angles between 100.45 and 104.15º. Each As atom is strongly bonded to three S atoms at S-As-S angles between 91.28 and 103.59º, forming an AsS_3 pyramid with As at its apex. The As-S linkages within the layers form rings of six AsS_3 pyramids. Interlayer bonding forces are interpreted as van der Waals. The structure of anorpiment is similar to that of orpiment in that it is composed of layers of As2S_3 macromolecules, but arranged in a different stacking sequence

Determination of Urinary Neopterin/Creatinine Ratio to Distinguish Active Tuberculosis from Latent Mycobacterium tuberculosis Infection.

BACKGROUND: Biomarkers to distinguish latent from active Mycobacterium (M.) tuberculosis infection in clinical practice are lacking. The urinary neopterin/creatinine ratio can quantify the systemic interferon-gamma effect in patients with M. tuberculosis infection. METHODS: In a prospective observational study, urinary neopterin levels were measured by enzyme linked immunosorbent assay in patients with active tuberculosis, in people with latent M. tuberculosis infection, and in healthy controls and the urinary neopterin/creatinine ratio was calculated. RESULTS: We included a total of 44 patients with M. tuberculosis infection and nine controls. 12 patients had active tuberculosis (8 of them culture-confirmed). The median age was 15 years (range 4.5 to 49). Median urinary neopterin/creatinine ratio in patients with active tuberculosis was 374.1 micromol/mol (129.0 to 1072.3), in patients with latent M. tuberculosis infection it was 142.1 (28.0 to 384.1), and in controls it was 146.0 (40.3 to 200.0), with significantly higher levels in patients with active tuberculosis (p < 0.01). The receiver operating characteristics curve had an area under the curve of 0.84 (95% CI 0.70 to 0.97) (p < 0.01). CONCLUSIONS: Urinary neopterin/creatinine ratios are significantly higher in patients with active tuberculosis compared to patients with latent infection and may be a significant predictor of active tuberculosis in patients with M. tuberculosis infection

Alcaparrosaite, K_3Ti^(4+)Fe^(3+)(SO_4)_4O(H_2O)_2, a new hydrophobic Ti^(4+) sulfate from Alcaparrosa, Chile

Alcaparrosaite, ideally K_3Ti^(4+)Fe^(3+)(SO_4)_4O(H_2O)_2, is a new mineral from the Alcaparrosa mine, Cerritos Bayos, El Loa Province, Antofagasta, Chile (IMA2011-024). The mineral occurs on and intergrown with coquimbite, and is also associated with ferrinatrite, krausite, pertlikite, pyrite, tamarugite and voltaite. It is a relatively early phase which forms during the oxidation of pyritic masses under increasingly arid conditions. Alcaparrosaite crystallizes from hyperacidic solutions in a chemical environment that is consistent with its association with coquimbite. It occurs as pale yellow blades and tapering prisms up to 4 mm in length, flattened on {010} and elongated along [100]. The observed crystal forms are {010}, {110}, {1.13.0} and {021}. The mineral is transparent and has a white streak, vitreous lustre, Mohs hardness of about 4, brittle tenacity, conchoidal fracture and no cleavage. The measured and calculated densities are 2.80(3) and 2.807 g cm^(−3), respectively. It is optically biaxial (+) with α = 1.643(1), β = 1.655(1), γ = 1.680(1) (white light), 2V_(meas) = 70(2)° and 2V_(calc) = 70.3°. The mineral exhibits strong parallel dispersion, r 2.704 (38) (2İ23,152); 1.9283 (30) (1İ55); 1.8406 (31) (3İ53,206). In the structure of alcaparrosaite (R_1 = 2.57% for 1725 F_o > 4σF), Ti^(4+) and Fe^(3+), in roughly equal amounts, occupy the same octahedrally coordinated site. Octahedra are linked into dimers by corner sharing. The SO_4 tetrahedra link the dimers into chains parallel to [001] and link the chains into undulating sheets parallel to {010}. The sheets link via 10- and 11-coordinated K atoms in the interlayer region. The structure shares some features with that of goldichite

Observation of near-surface damage by phonon scattering

We have investigated the feasibility of phonon-reflection techniques as nondestructive means to probe surface and/or near-surface damage in otherwise highly perfect crystals. An UHV liquid-helium stage, suitable for phonon-reflection measurements, was installed on a beam line of a tandem van de Graaff accelerator which was used to implant MeV ions into the substrate in order to modify the surface region in situ. Here, we report our investigation on the effects of 1-MeV Ar+ implantation in Al2O3 single crystals by monitoring the reflection of terahertz (THz) phonons (50-Å wavelength) from the implanted region. The results are compared to other surface techniques. Using a 15-kV ion gun on the same beam line, we have also bombarded Al2O3 crystals coated with thin films of gold. The effects of a 7.5-keV Ar+ beam on this Au-Al2O3 system are also discussed in this paper

Bobmeyerite, a new mineral from Tiger, Arizona, USA, structurally related to cerchiaraite and ashburtonite

Bobmeyerite, Pb_4(Al_(3)Cu)(Si_(4)O_12)(S_(0.5)Si_(0.5)O_4)(OH)_(7)Cl(H_(2)O)_3, is a new mineral from the Mammoth - Saint Anthony mine, Tiger, Pinal County, Arizona, USA. It occurs in an oxidation zone assemblage attributed to progressive alteration and crystallization in a closed system. Other minerals in this assemblage include atacamite, caledonite, cerussite, connellite, diaboleite, fluorite, georgerobinsonite, hematite, leadhillite, matlockite, murdochite, phosgenite, pinalite, quartz, wulfenite and yedlinite. Bobmeyerite occurs as colourless to white or cream-coloured needles, up to 300 mm in length, that taper to sharp points. The streak is white and the lustre is adamantine, dull or silky. Bobmeyerite is not fluorescent. The hardness could not be determined, the tenacity is brittle and no cleavage was observed. The calculated density is 4.381 g cm^(-3). Bobmeyerite is biaxial (-) with a ≈ b = 1.759(2), γ = 1.756(2) (white light), it is not pleochroic; the orientation is X = c; Y or Z = a or b. Electron-microprobe analyses provided the empirical formula Pb_(3.80)Ca_(0.04)Al_(3.04) Cu^(2+)_(0.96)Cr^(3+)_(0.13)Si_(4.40)S_(0.58)O_(24.43) Cl_(1.05)F_(0.52)H_(11.83). Bobmeyerite is orthorhombic (pseudotetragonal), Pnnm with unit-cell parameters a = 13.969(9), b = 14.243(10), c = 5.893(4) Å, V = 1172.5(1.4) Å 3 and Z = 2. The nine strongest lines in the X-ray powder diffraction pattern, listed as [d_(obs)(Å )(I)(hkl)], are as follows: 10.051(35)(110); 5.474(54)(011,101); 5.011(35)(220); 4.333(43)(121,211); 3.545(34)(040,400); 3.278(77)(330,231,321); 2.9656(88)(141,002,411); 2.5485(93)(051,222,501); 1.873(39)(multiple). Bobmeyerite has the same structural framework as cerchiaraite and ashburtonite. In the structure, which refined to R_1 = 0.079 for 1057 reflections with F > 4σF, SiO_4 tetrahedra share corners to form four-membered Si_(4)O_12 rings centred on the c axis. The rings are linked by chains of edge-sharing AlO_6 octahedra running parallel to [001]. The framework thereby created contains large channels, running parallel to [001]. The Cl site is centred on the c axis alternating along [001] with the Si_(4)O_12 rings. Two non-equivalent Pb atoms are positioned around the periphery of the channels. Both are elevencoordinate, bonding to the Cl atom on the c axis, to eight O atoms in the framework and to two O (H_(2)O) sites in the channel. The Pb atoms are off-centre in these coordinations, as is typical of Pb^2+ with stereo-active lone-electron pairs. A (S, Si, Cr)O_4 group is presumed to be disordered in the channel. The name honours Robert (Bob) Owen Meyer, one of the discoverers of the new mineral

Ionizing beam-induced adhesion enhancement and interface chemistry for Au-GaAs

MeV ion beam-induced adhesion enhancement of Au-films (∼500 Å thick) on p-type and n-type GaAs substrates has been studied by the scratch test, ESCA, and nuclear reaction hydrogen profiling. For films resistively deposited in a diffusion pumped chamber at 2−5×10^(−6)torr, the data indicate that the adhesion enhancement is associated with oxide layers on the substrate surface adsorbed before the film deposition. The ESCA data suggest that water vapour dissociates and forms Ga(OH)_3 at the interface layers under ionizing radiation. The oxide concentration at the interface varies with substrate electronic properties and gives a large difference in the adhesion enhancement. However, the data obtained so far on the hydrogen concentration at the interface indicate that within our range of sensitivity it is about the same for substrates with different electronic properties. Our data demonstrate the importance of a thin absorbed (impurity) layer for the interface chemistry and adhesion enhancement by ionizing radiation

The Lowland Maya "Protoclassic"

The term "Protoclassic," employed regularly but inexplicitly in the literature of lowland Maya archaeology, has become increasingly nebulous and ambiguous in both meaning and usage. This paper reviews the history and use of the term and presents a formal redefinition of the Protoclassic as a ceramic stage based explicitly and exclusively on ceramic criteria. Some suggestions regarding future use of the term also are offered. The paper further addresses and resolves a number of persisting questions regarding Protoclassic orange wares, including problems concerning the actual existence of the "Aguacate ceramic group." and the relationships of Aguacate-group pottery to other emergent orange wares of the terminal Late Preclassic and initial Early Classic periods. The nature and significance of the "Holmul I Style," the "Floral Park Ceramic Sphere." and the relationships of the two to each other and the larger, redefined "protoclassic" ceramic stage also are examined. A spatial distribution for protoclassic ceramics considerably expanded over what has ever been reported previously is described, and chronometric data are presented to support a revised chronology for the protoclassic ceramic stage. Finally, ceramic data are offered that suggest a real subdivision of the protoclassic ceramic stage into an early, emergent facet originating entirely within Late Preclassic lowland traditions, and a later, fully "Classic" facet corresponding to the early Tzakol (Tzakol 1) ceramic horizon