Plane-polarized Light Research Articles

Fluoroleakeite, NaNa2(Mg2Fe3+2Li)Si8O22F2, a new mineral of the amphibole group from the Verkhnee Espe deposit, Akjailyautas Mountains, Eastern Kazakhstan District, Kazakhstan: description and crystal structure

AbstractFluoroleakeite, NaNa2(Mg2Fe3+2Li)Si8O22F2 is a new mineral of the amphibole group from the Verkhnee Espe deposit, Akjailyautas mountains, eastern Kazakhstan district, Kazakhstan. The granites and their host rocks have been intensely reworked by post-magmatic and host-rock fluids, resulting in intense recrystallization, enrichment in F, Li and rare elements, and replacement of primary biotite and sodic-calcic amphiboles by Li-bearing riebeckite, aegirine, astrophyllite and other sodic minerals including fluoroleakeite. Crystals are prismatic parallel to [001] with {100} and {110} faces and cleavage surfaces, and the prism direction is terminated by irregular fractures. Grains are up to 3 mm long, and occur as isolated crystals, as small aggregates, and as inclusions in cámaraite. Crystals are black with a very pale grey to colourless streak. Fluoroleakeite is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.245 g cm–3. In plane-polarized light, it is pleochroic, X = pale grey-green, Y = medium grey, Z = grey-brown; X^a = 14.1° (in β obtuse), Y ‖ b, Z^c = 75.9° (in β acute). Fluoroleakeite is biaxial negative, α = 1.663(2), β = 1.673(2), γ = 1.680(2); 2Vobs = 80.9(6)°, 2Vcalc = 79.4°Fluoro-leakeite is monoclinic, space group C2/m, a = 9.8927(3), b = 17.9257(6), c = 5.2969(2) Å, β = 103.990(1)°, V = 905.7(1) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I)(hkl)]: 2.718(100)(151), 8.434(40)(110), 4.464(30)(021), 3.405(30)(131), 3.137(20)(310), 2.541(20)(), 2.166(20)(261), 2.325(15)(), 2.275(15)() and 2.806(10)(330). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 53.34, Al2O3 0.62, TiO2 1.27, V2O3 0.05, Fe2O3 15.10, FeO 6.00, MnO 2.04, ZnO 0.18, MgO 6.40, CaO 0.13, Na2O 9.08, K2O 1.98, Li2O 1.10, F 3.33, H2Ocalc 0.16, sum 99.39 wt.%. The formula unit, calculated on the basis of 23 O, is A(Na0.64K0.38)(Na1.98Ca0.02)(Li0.66Mg1.42Fe0.752+Mn0.262+Zn0.02Fe1.693+V0.013+Ti0.144+Al0.03) (Si7.93Al0.07)O22(F1.57OH0.16O0.27). Crystal-structure refinement shows Li to be completely ordered at the M(3) site. Fluoroleakeite, ideally NaNa2(Mg2Fe23+Li)Si8O22F2, is related to end-member leakeite, NaNa2(Mg2Fe23+Li)Si8O22(OH)2 by the substitution F → (OH).

Noonkanbahite, BaKNaTi2(Si4O12)O2, a new mineral species: description and crystal structure

AbstractNoonkanbahite, ideally BaKNaTi2(Si4O12)O2, is described as a new mineral species. At Liley [Löhley], Eifel Mountains, Germany (the holotype locality), it occurs as sprays of prismatic crystals (up to 8 mm) or single prismatic crystals (up to 4 mm) on walls of cavities in alkaline igneous rocks. At Murun, Siberia, Russia, noonkanbahite forms coarse lamellar crystals up to 0.05 cm × 0.7 cm × 1.5 cm embedded in kalsilite syenite. Noonkanbahite is brittle, H = 6, Dobs. = 3.39(1), Dcalc. = 3.49 g/cm3, has a vitreous lustre and does not fluoresce in ultraviolet light. It has poor cleavage on {010} and {100} and weak parting on {011}. Noonkanbahite is biaxial positive with 2Vobs. = 75(2)°, 2Vcalc. = 72.7(9)°, α 1.730(5), β 1.740(5) and γ 1.765(5), dispersion is medium, r < v. In transmitted plane-polarized light, noonkanbahite is strongly pleochroic, with X colourless, Y yellowish, Z straw-yellow; X = a, Y = b, Z = c. Noonkanbahite is orthorhombic, space group Imma, a = 8.0884(4), b = 10.4970(5), c = 13.9372(6) Å, V = 1183.3(1) Å3, Z = 4. The strongest ten X-ray diffraction lines in the powder pattern [d in Å (I)(hkl)] are: 2.907(100)(222), 8.353(50)(001), 3.196(50)(220), 2.097(50)(242), 2.241(40)(215), 2.179(40)(035), 3.377(30)(031), 2.694(30)(015), 2.304(30)(233), and 1.564(30)(064). Electron microprobe analysis gives SiO2 37.82, TiO2 15.54, ZrO2 0.42, Nb2O5 3.18, Al2O3 0.17, Fe2O3 (recalculated from FeO) 5.63, MnO 0.32, MgO 0.53, BaO 20.60, CaO 1.36, K2O 5.32, Na2O 6.14, F 0.78, H2O 0.58, sum 98.39 wt.%, (H2O determined by SIMS). The formula unit, calculated on the basis of 14 anions (O+OH+F), is (Ba0.85K0.13)Σ0.98(K0.59Na0.26Ca0.15)Σ1.00Na(Ti1.23Fe0.453+Nb0.15Mg0.08Mn0.03Zr0.02Al0.01)Σ1.97 (Si3.99Al0.01O12)(O1.33OH0.41F0.26)Σ2.00, Z = 4.The crystal structure was refined to R1 = 2.8% for 970 unique (F0 > 4σF) reflections collected on a Bruker single-crystal P4 diffractometer with a CCD detector and MoKα X-radiation. The crystal structure of noonkanbahite is isostructural with that of batisite, ideally BaNa2Ti2(Si4O12)O2, and scherbakovite, ideally K2NaTi2(Si4O12)O(OH). There are two octahedrally coordinated sites, M(1) and M(2), occupied by (Ti1.23Fe0.453+Nb0.15Mg0.08Mn0.03Zr0.02Al0.01), ideally Ti2 a.p.f.u. There are three interstitial A sites, [9]A(1), [8]A(2) and [6]A(3), occupied by Ba, K and Na, respectively. Si tetrahedra and M octahedra form a framework with interstitial cages occupied by Ba, K and Na atoms at the A sites. Noonkanbahite, BaKNaTi2(Si4O12)O2, is a K analogue of batisite, BaNa2Ti2(Si4O12)O2, and a Ba analogue of shcherbakovite, K2NaTi2(Si4O12)O(OH).

Nonlinear Faraday rotation and detection of superposition states in cold atoms

We report on the observation of nonlinear Faraday rotation with cold atoms at a temperature of $~100$ $\ensuremath{\mu}$K. The observed nonlinear rotation of the light polarization plane is up to $0.1$ rad over the $1$-mm-size atomic cloud in approximately $10$-mG magnetic field. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman sublevels created by a near-resonant light. The method allows for creation, detection, and control of atomic superposition states. It also allows applications for precision magnetometry with high spatial and temporal resolution.

Garutiite, (Ni,Fe,Ir), a new hexagonal polymorph of native Ni from Loma Peguera, Dominican Republic

Garutiite (Ni,Fe,Ir) is a new hexagonal polymorph of native Ni discovered in chromitite from Loma Peguera, Dominican Republic. The mineral was identified in heavy mineral concentrates obtained through the use of electric pulse disaggregation (EPD) and hydroseparation (HS) techniques. It forms as anhedral, botryoidal grains typically 10–60 μm in size (maximum of 110 μm). Grains are single or composite, frequently porous and zoned, and occasionally display an unusual lamellar internal texture. Associated minerals include hexaferrum, ferrian chromite, chlorite-group minerals, serpentine-group minerals, awaruite, irarsite, laurite, native Ru and unidentified species including Ru–Os–Ir-Fe and Pt–Ni–Fe–Ir compounds, Pt(Ni,Fe)3, (Fe,Ru,Ni,Os,Ir,Co)2S and RhNiAs. The mineral is megascopically grey to grey-black with a metallic luster. In plane-polarized light, garutiite is white in color, exhibits a very weak anisotropy, and no pleochroism, bireflectance or internal reflections were observed. No cleavage was noted and the hardness could not be determined owing to the porous nature of the mineral. The calculated density is 11.33 (1) g/cm3. Reflectance values (%) in air are: 63.8 at 470, 65.9 at 546, 67.0 at 589 and 68.0 at 650 nm. The average result of electron microprobe analyses ( n = 42 from 27 grains) is: Ni 27.91, Fe 19.94, Ir 43.78, Pt 6.98, Co 0.55, Cu 0.43, Ru, 0.50, Rh 0.74, Os 0.67, total 101.51 wt%, corresponding to (Ni0.421Fe0.316Ir0.202Pt0.032Co0.008Cu0.006Rh0.006Ru0.004Os0.003)∑1 or the simplified formula, (Ni,Fe,Ir). Garutiite is the Ni analogue of hexaferrum, osmium and ruthenium and is classified as belonging to the osmium group. As such, the mineral is considered to be hexagonal, crystallizing in space group P 63/ mmc with a 2.6941(4) and c 4.2731(6) A , V = 26.86(1) A 3, Z = 2. The strongest lines of the X-ray powder diffraction pattern [ d (in A )(I)( hkl )] are: 2.330(50)(100), 2.136(30)(002), 2.046(100)(101), 1.576(30)(102), 1.3470(40)(110), 1.2155(40)(103). Based on its morphology, internal texture, and the associated minerals, garutiite is interpreted to be secondary in origin, i.e ., having formed at low temperatures during post magmatic processes, such as serpentinization and/or lateritization. The name honors Prof. Giorgio Garuti, in recognition of his contributions to the understanding of the mineralogy of platinum-group elements.

FERRO-OBERTIITE, Na Na2 (Fe2+ 3 Fe3+Ti) Si8 O22O2, A NEW MINERAL SPECIES OF THE AMPHIBOLE GROUP FROM COYOTE PEAK, HUMBOLDT COUNTY, CALIFORNIA

Ferro-obertiite, Na Na 2 (Fe 2+3 Fe 3+ Ti) Si 8 O 22 O 2 , is a new mineral species of the amphibole group from Coyote Peak, Humboldt County, California, U.S.A., associated with inclusions of lithic-wacke sandstone in an alkali-rich ultramafic diatreme. Ferro-obertiite occurs as euhedral to subhedral crystals up to 1.25 mm across in a matrix of aegirine and feldspar. Crystals are black with a grey streak. Ferro-obertiite is brittle, has a Mohs hardness of 6, and a splintery fracture; it is non-fluorescent, with perfect {110} cleavage, no observable parting, and has a calculated density of 3.330 g cm −3 . In plane-polarized light, it is pleochroic, X dark brown, Y brown, Z dark grey; X ∧ a = 77.3° (in β acute), Y || b , Z ∧ c = 91.2° (in β obtuse). Ferro-obertiite is biaxial negative, α 1.671(1), β 1.674(1), γ 1.675(1); 2 V (obs.) = 60(3)°, 2 V (calc.) = 59.9°. It is monoclinic, space group C 2/ m , a 9.845(4), b 18.018(8), c 5.296(3) A, β 103.86(3)°, V 912.1(4) A 3 , Z = 2. The strongest ten X-ray-diffraction lines in the powder pattern [ d in A( I )( hkl )] are: 2.722(100)(331,151), 8.448(80)(110), 3.407(60)(131, 041), 3.144(50)(201, 310), 2.596(50)(061), 2.533(40)(202), 2.178(30)(261), 4.514(20)(040, 021), 3.283(20)(240) and 2.332(20)(351). Analysis by a combination of electron microprobe and crystal-structure refinement gave SiO 2 52.47, Al 2 O 3 0.09, TiO 2 6.51, Fe 2 O 3 4.54, FeO 18.43, MgO 5.74, MnO 0.15, CaO 0.90, Na 2 O 8.70, K 2 O 1.51, Li 2 O 0.17, F 0.51, H 2 O 0.58, sum 100.09 wt%. The formula unit, calculated on the basis of 24 (O, OH, F), is A (Na 0.72 K 0.29 ) (Na 1.85 Ca 0.15 ) (Mg 1.30 Fe 2+ 2.35 Mn 2+ 0.02 Fe 3+ 0.52 Al 0.01 Ti 0.75 Li 0.10 ) (Si 7.99 Al 0.01 ) O 22 (O 1.16 F 0.25 OH 0.59 ). The crystal-structure refinement shows Ti to be strongly ordered at the M (1) site. Ferro-obertiite, ideally Na Na 2 (Fe 2+ 3 Fe 3+ Ti) Si 8 O 22 O 2 , is related to obertiite, Na Na 2 (Mg 3 Fe 3+ Ti) Si 8 O 22 O 2 , by the substitution Fe 2+ → Mg.

Tailored Silicon Nanopost Arrays for Resonant Nanophotonic Ion Production

Nanostructures that have dimensions commensurate with the wavelength of the electromagnetic radiation exhibit near-field effects and, as optical antennas, can couple laser radiation to the local environment. Laser-induced silicon microcolumn arrays behave as nanophotonic ion sources that can be modulated by rotating the plane of light polarization. However, the limited range of surface morphologies available for these substrates makes it difficult to study the underlying mechanism that governs ion production. Here we demonstrate that nanopost arrays (NAPAs) can be tailored to exhibit resonant ion production. Ion yields from posts with subwavelength diameter show sharp resonances at high aspect ratios. The resonant enhancement in ion intensities can be modulated by adjusting the periodicity. In addition to strong molecular ion formation, the presence of high-energy fragmentation channels is observed. Ion yields from NAPAs exhibit dramatic differences for p- and s-polarized laser beams, indicating that energy coupling is similar to antenna arrays. These nanophotonic ion sources can control the degree of ion fragmentation and could eventually be integrated with micromachined mass spectrometers and microfluidic devices.

MINERALOGICAL DATA ON ANGELAITE, Cu2AgPbBiS4, FROM THE LOS MANANTIALES DISTRICT, CHUBUT, ARGENTINA

Angelaite, ideally Cu2AgPbBiS4, occurs as a hypogene mineral in polymetallic ores at the Angela groups of veins in the mining district of Los Manantiales, in the province of Chubut, Argentina. The new mineral species is predominantly associated with pyrite, sphalerite, chalcopyrite, hematite, native gold and galena; less common associates are aikinite, wittichenite, miharaite and cervelleite. Angelaite forms subhedral, commonly oriented inclusions in galena; these may attain a size of up to 200 x 50 mm. The mineral is grey in color with a brownish tint, opaque, and lacks internal reflections. It has a metallic luster and a dark grey streak. The VHN10 ranges between 245 and 263 kg/mm(3) (mean 253), corresponding to a Mohs hardness of 3 1/2. In plane-polarized light, it is strongly bireflectant and pleochroic from light grey with a brownish tint to light cream with a greenish tint. Angelaite is strongly anisotropic, with rotation tints in shades of pale grey, deep green and deep blue. We provide the measured values of reflectance in air and oil. The average of 23 electron-microprobe analyses is: Cu 16.7(3), Ag 13.4(2), Pb 27.8(6), Bi 26.6(5), S 16.0(2), total 100.5(5) wt.%, equivalent to Cu2.07Ag0.97Pb1.05Bi1.00S3.91. The ideal formula (on the basis of nine atoms) is Cu2AgPbBiS4, which requires Cu 16.31, Ag 13.84, Pb 26.58, Bi 26.81, S 16.45, total 100 wt.%. Angelaite is orthorhombic, with a 12.734(5), b 4.032(1), c 14.633(5) angstrom, V 751.8(5) angstrom(3), space group Pnma and Z = 4. The calculated density is 6.934 g/cm(3). It is a homeotype of galenobismutite, with Cu and Ag replacing one of the Bi positions in a complicated way. The strongest eight lines in the calculated powder-diffraction pattern [d in angstrom(I)(hkl)] are 3.672(100)(032), 3.660(64)(004), 3.407(60)(120), 3.319(62) ((1) over bar 21), 3.317(62)(121), 3.111(69)(041), 3.022(72)((1) over bar 13) and 3.017(72)(113). The mineral is named after the location. Both the mineral and its name were approved by the CNMNC (IMA #2003-064).

Optical Activity of an Asymmetric Substance

This paper reported the investigation on the property of optical activity from three different isomers of L-, Dand DL--alanine (CH3CHNH2CO2H), a proposed radiation dosimetric material. The aim was to confirm the impact of attachment of -carbon atom of the systems to the four different groups, that is, the -carbon or methyl group, H-group, CO2H-group and NH2-group, to their response to any incoming plane-polarized light. Optical activity of a substance is a measure of the ability of a substance to rotate a plane of polarization, if solution of the substance is placed in the path of plane-polarized light. A polarimeter of Perkin-Elmer Model 141 with a Sodium lamp of 584-nm wavelength (D-line) and equipped with a digital counter was occupied in this work to measure the number of degrees of rotation of plane-polarized light at room temperature due to 8.3% concentration of each L-, D- and DL--alanine solutions. It was obtained that molecules of L-isomer rotate the counter of the polarimeter clockwise, from the observer’s point a view. While the molecules of D-isomer rotate the counter anti clockwise, at the similar amount of rotation. These results confirm the asymmetric structure belong to the -alanine system. Molecules of DL-isomer, however, do not rotate the counter at all. The existence of similar number of the D- and L-molecules in the DL-solution is the cause.

多波長偏光を用いたサブミクロン粒径計測(熱工学,内燃機関,動力など)

Feasibility of a newly developed size determination method for sub-micron particles using multi-wavelength polarized lights is investigated, experimentally. According to the Mie's theory the polarization ratios of scattered lights are calculated numerically, which is a function of the particle diameter, the refraction index, and the wavelength of the incident light. Polystyrene particles are used as the test particles, which are suspended in purified water. The arithmetic mean diameters of them are varied from 0.356 to 0.77μm, which is measured with a centrifugal sedimentation method. In order to extend the measurement range of convestional polarization ratio methods, three kinds of He-Ne lasers, whose wavelengths are 543.5, 594.1, and 632.8nm, are used. The laser beams passes through the particles, and the scattered images are acquired with a digital CCD camera set in parallel and perpendicular directions to the polarization plane of the incident light. The polarization ratios of the scattered lights are estimated from these scattered light images, and the acquired data are compared with the analytical values. It is shown that, by use of the multi-wavelength polarization ratio method, the measurement range of the particle size can be extended up to the order of 1μm, and that the accuracy of the results lies from 0.1% to 7.6%, when compared with the results of a centrifugal sedimentation method.

Fluoro-aluminoleakeite, NaNa2(Mg2Al2Li)Si8O22F2, a new mineral of the amphibole group from Norra Kärr, Sweden: description and crystal structure

AbstractFluoro-aluminoleakeite, ideally , is a new mineral of the amphibole group from Norra Kärr, Sweden (IMA-CNMMNC 2009-012). It occurs in a proterozoic alkaline intrusion that mainly comprises a fine-grained schistose agpaitic nepheline-syenite (grennaite). Fluoro- aluminoleakeite occurs as isolated prismatic crystals 0.10–2 mm long in a syenitic matrix. Crystals are light greenish-blue with a greenish-blue streak. It is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.14 g cm–3. In plane-polarized light, it is pleochroic, X = pale green, Y = dark green, Z = pale green; X ^ a = 62.9° (in β obtuse), Y || b. Fluoro-aluminoleakeite is biaxial negative, α = 1.632(1), β = 1.638(1), γ = 1.643(1); 2Vobs. = 98.0(4)°, 2Vcalc. = 95.5°.MFluoro-aluminoleakeite is monoclinic, space group C2/m, a = 9.7043(5) Å, b = 17.7341(8) Å, c = 5.2833(3) Å, β = 104.067(4)°, V = 882.0(2) Å3, Z = 2. The eight strongest X-ray diffraction lines in the powder-diffraction pattern are [d in Å, (I), (hkl)]: 2.687, (100), (31, 151); 4.435, (80), (021, 040); 3.377, (80), (131); 2.527, (60), (02); 8.342, (50), (110); 3.096, (40), (310); 2.259, (40), (71, 12) and 2.557, (30), (002, 061). Analysis, by a combination of electron microprobe and crystal-structure refinement, gives SiO2 58.61, Al2O3 7.06, TiO2 0.32, FeO 3.27, Fe2O3 6.05, MgO 8.61, MnO 0.73, ZnO 0.43, CaO 0.05, Na2O 9.90, K2O 2.43, Li2O 1.62, F 3.37, H2Ocalc. 0.50, sum 101.08 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F,Cl) p.f.u. with (OH) + F = 2 a.p.f.u., is A(Na0.65 O22W(F1.47OH0.53)Σ=2.00. Crystal-structure analysis shows CLi to be completely ordered at the M(3) site, and provided reliable site populations. Fluoro-aluminoleakeite is related to the end-member leakeite, , by the substitutions CFe3+ → CAl and WF → W(OH).

Tazieffite, Pb20Cd2(As,Bi)22S50Cl10, a new chloro-sulfosalt from Mutnovsky volcano, Kamchatka Peninsula, Russian Federation

Tazieffite, ideally Pb20Cd2(As,Bi)22S50Cl10, is a new mineral from the high-temperature fumaroles of the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as tiny, slender, needle-shaped crystals, up to 400 μm long and 10 μm across, generally forming fibrous aggregates. Tazieffite is closely associated with greenockite, galena, mutnovskite, kudriavite, and Cd-rich cannizzarite. Other minerals spatially associated are pyrite, anhydrite, and cristobalite. Tazieffite is silvery-gray in color, occasionally with a magenta tint when it forms aggregates of extremely fine needles. It has a black streak and metallic luster. In plane-polarized incident light, tazieffite is weakly bireflectant and weakly pleochroic from dark gray to a blue-gray. Between crossed polars, the mineral is weakly anisotropic, without characteristic rotation tints. Reflectance percentages measured in air ( R min and R max) for a single grain are 33.9, 34.1 (471.1 nm), 32.8, 33.0 (548.3 nm), 32.4, 32.6 (586.6 nm), and 30.9, 31.1 (652.3 nm), respectively. Electron microprobe analyses yield the following ranges of concentrations: Pb 41.88–44.14 (avg. 42.90), Cd 0.87–1.16 (avg. 1.03), Sn 0.31–0.69 (avg. 0.48), Bi 20.43–22.94 (avg. 21.90), As 8.64–10.73 (avg. 9.66), S 16.10–17.48 (avg. 16.58), Se 0.82–1.28 (avg. 1.04), Cl 2.39–2.77 (avg. 2.63), Br 0.09–0.15 (avg. 0.12), I 0.27–0.58 (avg. 0.42). The empirical chemical formula, calculated on the basis of 44 cations, is Pb20.06(Cd0.89Sn0.39In0.02)∑1.30(As12.49Bi10.15)∑22.64 (S50.08Se1.28)∑51.36(Cl7.18I0.32Br0.15)∑7.65. Tazieffite is closely related to the halogen-sulfosalt vurroite, Pb20Sn2Bi22S54Cl6, both from a chemical and structural point of view. It represents the (Cd,As)-dominant of vurroite, according to the coupled heterovalent substitution Sn4+ + 2S2− → Cd2+ + 2Cl−. The crystal structure of tazieffite was refined in the space group C 2/ c to R = 0.0370 for 4271 reflections with I > 2σ( I ). Unit-cell parameters are a = 8.3520(17), b = 45.5920(92), c = 27.2610(55) A, β = 98.84(3)°, with V = 10257(4) A3, and Z = 4. The structure of tazieffite consists of lozenge-shaped composite rods made of coordination polyhedra of Pb around an octahedrally coordinated (Cd,Sn,Pb) position, interconnected into layers parallel to (010). These layers are separated by ribbons of As and Bi in distorted octahedral coordination. The ribbons form wavy, discontinuous double layers of the PbS archetype. Lone electron pairs of As and Bi are accommodated in the central portions of the PbS-like layers. The possibility that small amounts of NH4+ are incorporated in the crystal structure of tazieffite is discussed. The name of this new mineral species (IMA 2008-012) honors Haroun Tazieff (Warszawa, May 11, 1914–Paris, February 6, 1998), famous Belgian/French volcanologist, who was a pioneer in the field study of volcanoes and devoted his life to the study of volcanic gases.

Identification at autopsy of pulverized pills in lungs of a first-time methadone user

We recently encountered a 25-year-old white man who died of substance abuse including methadone. The route of administration of the drug(s) appears to have been insufflation. He was found dead at home. There were bottles of prescribed medications and an empty bottle of non-prescribed methadone. There was a grinding device nearby. At autopsy, no needle tracts were identified. Microscopically, the bronchi had desquamated ciliated respiratory epithelium admixed with red-brown pigment, which was found under plane-polarized light to be comprised of birefringent finely-granular material consistent with pulverized pills. Blood toxicology was positive for tetrahydrocannabinol, sertraline, nicotine, and methadone. The cause of death was ruled drug interactions with cerebral and pulmonary edema, the manner of death accidental. The decedent fit a profile of a victim of prescription drug abuse, for whom the mode of administration of drugs may be altered from intended use in as many as 80% of cases.

Strand-like phase separation in mixtures of xanthan gum with anionic polyelectrolytes

Binary aqueous mixtures of xanthan gum with anionic polyelectrolytes (alginate, polyacrylate, carboxymethylcellulose, λ-carrageenan, and low methoxyl pectin) exhibited phase separation above threshold concentrations of added polyelectrolyte. Dynamic oscillatory rheology showed that separation was associated with a large decrease in storage modulus, and when viewed under plane-polarised light, the dispersed phase exhibited a birefringent, strand-like morphology indicative of a liquid crystalline phase. At constant xanthan concentration, the strand thickness was inversely related to the viscosity of the added polyelectrolyte solution. Phase diagrams obtained for xanthan:alginate, and xanthan:carboxymethylcellulose mixtures showed that whilst the strands contained both xanthan and polyelectrolyte, the continuous phase was xanthan-free. Mixtures of xanthan gum with neutral polysaccharides (maltodextrin, methylcellulose) did not show phase separation, and separation was not observed when xanthan was replaced by scleroglucan a neutral polysaccharide which, like xanthan, adopts a stiff, helical structure in solution. The alginate concentration required to initiate phase separation was inversely related to alginate molecular weight, and was independent of the alginate mannuronate/guluronate ratio. Higher concentrations of alginate were required to elicit phase separation when the salt content of the mixture was increased. The results suggest that segregative phase separation, driven by repulsive interactions between polyelectrolytes, promotes the formation of liquid crystalline structures in the xanthan-rich domain. The consequence is that the decreased viscosity reported when xanthan solutions undergo liquid crystal formation, occurs at much lower xanthan concentrations, when in the presence of an anionic polyelectrolyte.

Fluoro-sodic-ferropedrizite, NaLi2(Fe22+Al2Li)Si8O22F2, a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia: description and crystal structure

AbstractFluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia. It occurs at the endogenic contact of a Li-pegmatite with country rocks near to a diabase dyke and formed by reaction of the pegmatitic melt with the country rock. Fluoro-sodic-ferropedrizite occurs as prismatic to acicular crystals, ranging in length from 0.1–3 cm and widths of up to 50 μm. Crystals occur inparallel to sub-parallel aggregates up to 5 mm across ina matrix of calcite and plagioclase feldspar. Crystals are pale bluish-grey with a greyish-white streak.Fluoro-sodic-ferropedrizite is brittle, has a Mohs hardness of ~6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.116 g cm–3. In plane-polarized light, it is pleochroic, X = pale purple-grey, Y = light grey, Z = colourless; X ^ a = 71.2º (in β acute), Y || b, Z ^ c = 83.4º (in β obtuse). Fluoro-sodic-ferropedrizite is biaxial positive, α = 1.642(1), β = 1.644(1), γ = 1.652(1); 2V(obs) = 68.0(3)º, 2V(calc) = 56.4º. Fluoro-sodic-ferropedrizite is monoclinic, space group C2/m, a = 9.3720(4) Å, b = 17.6312(8) Å, c = 5.2732(3) Å, β = 102.247(4)º, V = 851.5(2) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder patternare (d in Å ,(I),(hkl)): 8.146,(10),(110); 2.686,(9),(151); 3.008,(8),(310); 4.430,(7),(021); 2.485,(6),(02); 3.383,(4),(131); 2.876,(3),(51, 11); 2.199,(3),(12); 4.030,(2),(111) and 3.795,(2),(31). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 59.81, Al2O3 12.66, TiO2 0.09, FeO 10.32, MgO 5.56, MnO 0.73, ZnO 0.17, CaO 0.20, Na2O 2.81, Li2O 4.80, F 2.43, H2Ocalc 1.10, sum = 99.65 wt.%. The formula unit, calculated on the basis of 24(O,OH,F) is A(Na0.68)B(Li1.92Na0.05Ca0.03)C() T(Si7.98Al0.02)O22W(F1.03OH0.97). Crystal-structure refinement shows Li to be completely ordered at the M(3) and M(4) sites. Fluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is related to the theoretical end-member ‘sodic-pedrizite’, ANaBLi2C(Mg2Al2Li)TSi8O22W(OH)2, by the substitutions CFe2+ → CMg and WF → W(OH).

PASAVAITE, Pd3Pb2Te2, A NEW PLATINUM-GROUP MINERAL SPECIES FROM THE NORIL'SK-TALNAKH Ni-Cu CAMP, RUSSIA

Pasavaite, Pd 3 Pb 2 Te 2 , is a new palladium-bearing mineral species discovered at the Talnakh deposit, Noril’sk–Talnakh Ni–Cu camp, Taimyr Autonomous District, Russia. It was observed in two polished sections, where it occurs as subhedral grains not exceeding 20 μm in diameter embedded in polarite, and accompanied by unknown Pd–Pb–Bi–Te phases and sperrylite or intergrown with Au–Ag phases. The other associated minerals are: taimyrite, froodite, galena, and the chalcopyrite + pentlandite matrix. Synthetic pasavaite is megascopically grey in color, has a metallic luster and a grey streak. The mineral is brittle, with a weak {001} cleavage. Values of VHN 25 (15 indentations on five grains of synthetic Pd 3 Pb 2 Te 2 ) range between 173 and 281, for a mean value of 233 kg/mm 2 , which corresponds to a Mohs hardness of approximately 2. In plane-polarized light, pasavaite is pale pink with brownish tinge, has strong bireflectance, pleochroic from brownish to light pink, distinctly to strongly anisotropic, and exhibits no internal reflections. Reflectance values of synthetic pasavaite in air (R max , R min ) are: 49.9, 42.4 at 470 nm, 51.8, 44.6 at 546 nm, 52.2, 45.7 at 589 nm, and 52.8, 46.9 at 650 nm. The average result of four electron-microprobe analyses of pasavaite is: Pd 31.51, Pb 41.54, Bi 0.19, and Te 25.75, total 98.99 wt.%, corresponding to an empirical formula (based on 7 atoms) Pd 2.96 (Pb 2.01 Bi 0.01 )Te 2.02 ; synthetic pasavaite (average of seven analyses) gave: Pd 32.17, Pb 41.78, and Te 25.93, total 99.88 wt.%, corresponding to Pd 2.99 Pb 2.00 Te 2.01 . The mineral is orthorhombic, space group Pmmn , with a 8.599(1), b 5.9381(6), c 6.3173(8) A, V 322.6(1) A 3 , and Z = 2. The crystal structure was solved and refined from the powder X-ray-diffraction data of synthetic Pd 3 Pb 2 Te 2 . Pasavaite is structurally related to shandite and parkerite. The strongest lines in the X-ray powder-diffraction pattern of synthetic pasavaite [ d in A(I)( hkl )] are: 6.3152(34)(001), 3.1572(33)(002), 3.0495(100)(211), 2.5456(63) (202), 2.4424(34)(220), 2.2786(42)(221), 2.1637(71)(022), 2.1496(30)(400), 1.8906(42)(203), and 1.5248(31)(422). The mineral is named after Jan Pasava, in recognition of his important contributions to the geochemistry of platinum-group elements in anoxic environments and related ore deposits.

Coupling of IR measurements and multivariate calibration techniques for the determination of enantiomeric excess in pharmaceutical preparations

Enantiomers are isomers that are the mirror image of one another and that, except for the property of rotating the plane-polarized light in opposite direction, share common physical and chemical properties. However, quite often it can happen that their pharmacological properties are significantly different so that one enantiomer is active while the other one doesn't produce any effect or, in some cases, can result even noxious. It is evident, therefore, that the possibility of determining the excess of the most abundant enantiomer in a mixture (enantiomeric excess) is of capital importance, especially in the quality control of drugs. In this paper, the possibility of quantifying the enantiomeric excess in mixtures of two pharmacologically important active principles (namely mandelic acid and ketoprofen) by means of multivariate calibration of IR data is explored. Since the measurements are carried out on KBr pellets, different background correction and data pre-treatment techniques have been used. Pretreated data have then been analyzed by Partial Least Squares Regression (PLS) and Multivariate Curve Resolution (MCR), considering at first the whole spectrum and later just a more limited spectral region selected by a sequential application of backward interval PLS and genetic algorithms (bi-PLS-GA). Results have proved to be significantly accurate both by internal and external validation.

MARIANOITE, A NEW MEMBER OF THE CUSPIDINE GROUP FROM THE PRAIRIE LAKE SILICOCARBONATITE, ONTARIO

Marianoite, a new member of the cuspidine group of minerals, occurs in phlogopite–calcite silicocarbonatite in the western part of the Mesoproterozoic Prairie Lake intrusive complex, in northwestern Ontario, Canada. The mineral forms flattened prismatic crystals with resorbed faces, up to 0.3 mm in length, and is associated with uranoan pyrochlore, titanite and natrolite–muscovite pseudomorphs after xenocrystic nepheline. The crystals are translucent, very pale yellow macroscopically and colorless in plane-polarized light. The mineral is biaxial negative (α 1.700, β 1.715, γ 1.725, 2 V meas 80°, 2 V calc 78°) and shows a weak optic-axis dispersion ( r v ). Marianoite is relatively homogeneous in composition; its average empirical formula is Na 1.93 (Ca 4.00 Mn 0.04 ) ∑4.04 (Nb 0.97 Zr 0.90 Ti 0.09 Fe 0.08 Mg 0.03 Hf 0.01 ) ∑2.08 (Si 3.97 O 14 )O 2.93 F 1.07 . By analogy with wohlerite, the simplified formula of marianoite should be written Na 2 Ca 4 (Nb,Zr) 2 (Si 2 O 7 ) 2 (O,F) 4 . The structure of the new mineral species, refined by single-crystal methods to an R 1 of 4.65% (for | F o | > 4σ F ), is monoclinic, space group P 2 1 ; the unit-cell parameters are: a 10.8459(15) A, b 10.2260(14) A, c 7.2727(10) A, β 109.332(3)°, V 761.1(3) A 3 ( D calc 3.45 g/cm 3 ). The mineral is isostructural with wohlerite [Na 2 Ca 4 (Zr,Nb) 2 (Si 2 O 7 ) 2 (O,F) 4 ], but shows the preponderance of Nb in the smallest octahedrally coordinated cation sites in its crystal structure. The occupancy of these sites cannot be determined accurately because of the similar X-ray scattering characteristics and ionic radii of Nb 5+ and Zr 4+ . The mineral is named in honor of Anthony Nicola Mariano (b. 1930), in recognition of his contributions to the study of alkaline rocks and carbonatites.

Electrooptic properties of films of azopolymers and polycomplexes with donor and acceptor substituents

This paper discusses the absorption spectra of films of new azopolymers and polycomplexes of azobenzene derivatives with cobalt before and during the switching on of an electric field. It has been detected that an external electric field affects the transmission by the films of plane-polarized light at the long-wavelength absorption edge. This effect is caused by spatial reorientation of the dipole moments of azobenzene groups, photoinduced by polarized light in an external electric field. The fact that an electric field affects the transmission of light is explained by the appearance of forces that act on the dipole moments of the azobenzene groups and on the metal ions. The increase of the dipole moment of the azobenzene groups when donor or acceptor substituents are introduced into their composition reduces the influence of metal ions on the electrooptic properties of the polycomplex films.

DARET assays of BoNT proteolytic activity with a fully recombinant substrate

The DARET (Depolarization After Resonance Energy Transfer) assay is a homogenous, coupled FRET-fluorescence polarization (FRET-FP) assay for BoNT/A or /E proteolytic activity that relies on a fully recombinant substrate. The substrate consists of BFP and GFP proteins flanking SNAP-25 residues 134–206. In the assay, the substrate is excited with plane-polarized light at 379 nm, which primarily excites the BFP, while emission from the GFP at 509 nm is monitored. Energy transfer from BFP to GFP in the intact substrate results in a substantial depolarization of the GFP emission. Upon cleavage by toxin, the BFP and GFP domains are spatially separated, the energy transfer is eliminated, and the polarization of the GFP emission increases. This increase in polari¬zation can be monitored to assay the proteolytic activity of low picomolar concentrations of Type A and Type E toxin in real time. The assay is amenable to high-throughput applications, and the substrate can also be used in a traditional FRET assay.

A Polarized Viewpoint?

Invertebrates, like vertebrates, use the light-activated heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR) rhodopsin as a photoreceptor in visual signal transduction. Unlike vertebrate rhodopsin, which signals through transducin, invertebrate rhodopsin signals through G q -type G proteins to stimulate an inositol 1,4,5-trisphosphate-based signaling pathway (see Schertler). Murakami and Kouyama determined the 2.5 Å resolution crystal structure of squid rhodopsin, shedding new light on mechanisms of signaling involving this GPCR family. Crystallization of truncated squid rhodopsin (lacking a C-terminal extension that is not involved in signal transduction) revealed two cytoplasmic helices as well as the seven transmembrane helices characteristic of GPCRs. Transmembrane helices V and VI projected 25 Å into the cytoplasm to form, together with cytoplasmic helices VIII and IX, a structure that is not present in bovine rhodopsin, which the authors propose is involved in interactions with G q . Rhodopsin consists of the protein opsin and the covalently bound chromatophore retinal; the amino acid residues in contact with retinal in squid rhodopsin differ from those in bovine rhodopsin, and retinal assumes a less distorted configuration in the former. Intriguingly, the arrangement of chromatophores in crystallized squid rhodopsin may provide insight into the ability of invertebrates to detect the polarization plane of light. M. Murakami, T. Kouyama, Crystal structure of squid rhodopsin. Nature 453 , 363-367 (2008). [PubMed] G. F. X. Schertler, The rhodopsin story continued. Nature 453 , 292-293 (2008). [PubMed]