Black Needles Research Articles

Tb2O@C2(13333)-C74: A Non-Isolated Pentagon Endohedral Fullerene Containing a Nearly Linear Tb-O-Tb Unit.

Terbium has been added to the list of elements that form oxide clusters inside fullerene cages. Tb2O@C2(13333)-C74 has been isolated as a byproduct of the electric arc synthesis of the azafullerene Tb2@C79N. Cocrystallization of Tb2O@C2(13333)-C74 with Ni(OEP) (where OEP is the dianion of octaethylporphyrin) in toluene yielded black needles of Tb2O@C2(13333)-C74·NiII(OEP)·1.5C7H8 that have been examined by single-crystal X-ray diffraction. The resulting structure shows that a nearly linear Tb-O-Tb unit is contained in a C2(13333)-C74, which has two sites where pentagons share an edge to form pentalene units at opposite ends of the fullerene. Unlike the usual situations where metal atoms in fullerenes that do not obey the isolated pentagon rule are situated within the folds of the pentalene units, the Tb atoms in Tb2O@C2(13333)-C74 are positioned to the side of the pentalene units and near-neighboring hexagons. The magnetic properties of Tb2O@C2(13333)-C74 have been examined starting from the experimental geometry, using ab-initio multiconfigurational methods. The computations predict that Tb2O@C2(13333)-C74 will show strong axiality, which would make it a single-molecule magnet with a large magnetic anisotropy barrier.

Possibilities for obtaining pellets by single-screw extrusion of biomass from black pine (Pinus nigra Arn.)

The aim of the present study was to investigate the possibilities for obtaining pellets by single-screw extrusion of black pine (Pinus nigra Arn.) biomass. Two fractions of black pine needles – 1) with dp ≥ 500 μm and bulk density ρn = 0.243 g/cm3 and 2) black pine twigs with d ≥ 500 μm and ρn = 0.297 g/cm3, were obtained. Wheat bran with dp ≥ 500 μm and bulk density ρn = 0.258 g/cm3 in a ratio of 1:1 was added to the obtained fractions. The experiments showed that getting pellets by single-screw extrusion of biomass from twigs and needles of black pine was possible when mixing them in a 1:1 ratio with wheat bran. The addition of wheat bran improved the smoothness and homogeneity of the produced pellets and increased their density. High-density pellets with a low sectional expansion index were produced during extrusion. The productivity of extruding mixtures of black pine twigs with wheat bran was 30% higher than that made from a mix of black pine needles and wheat bran. The pellets obtained after mixing biomass from black pine and wheat bran had over 13% higher density than those produced entirely from wheat bran. The presence of black pine biomass increased the quality of the final product while at the same time having a positive effect on both productivity and specific energy consumption.

Coniferous Diseases In The Andijan Region

The article provides data on the composition of diseases of decorative coniferous crops in the Andizhan region. In total, 11 species of micromycetes were identified. In the nursery, during the lodging of seedlings, species of the river were noted. Fusarium: Fusarium oxysporum Schlecht. and F. solani (Mart.) Sacc., Verticillium dahlia Klebn. By the frequency of occurrence, Fusarium blight was noted much more often. Lodging of seedlings was also caused by Pythium debaryanum Hesse. Among the diseases of adult plants, we have identified - rust juniper (exc. - Gymnosporangium confusum Plowr.), defeat of needles (phomosis, rust), shoots and branches (diplodiosis, phomosis). drying of needles and juniper shoots and black needles (Hormiscium pinophilum (Nees.) Lind., Fumago vagans Pers.).

Effects of feeding graded levels of black spruce needles and branches on beef cow performance and health during mid to late gestation

Pregnant beef cows (56; 727 ± 102 kg body weight) in their second trimester were used to examine black spruce (BSP) needles and branches for replacing alfalfa silage in wintering cow diets. Five dietary treatments assessed BSP inclusion rates (0%, 15%, 22.5%, 30%, and 37.5% in the diet) for 92 d up until 2 wk before start of calving using a randomized complete block design (10–12 cows per treatment). There were linear decreases (P < 0.001) in total weight gain, average daily gain, and dry matter intakes (DMI) as amounts of dietary BSP increased. Low DMI feeding BSP may be attributed to palatability issues and lower rates of digestion. Changes in body condition score increased (P < 0.003) as dietary BSP increased. These effects are supported by corresponding linear decreases (P < 0.001) for changes in rump fat cover and increases (P < 0.001) in serum non-esterified fatty acids as dietary BSP increased. After feeding the test diets, there were no dietary treatment differences (P > 0.42) for calf birth and weaning weights as well as cow pregnancy and culling rates. Based on this study, incorporation of BSP into gestating cow diets cannot be recommended.

Synthesis, Crystal Structure, and Selected Properties of [Au(S2 CNH2 )2 ]SCN: A Precursor for Gold Macro-Needles Consisting of Gold Nanoparticles Glued by Graphitic Carbon Nitride.

A new preparation route is developed for the synthesis of needle-like crystals of [Au(S2 CNH2 )2 ]SCN, which avoids disproportionation of the AuI salt used as a starting material. In the crystal structure, the two crystallographically independent AuIII centers are in a square-planar environment of two S2 CNH2 ligands. The Hirshfeld surface analysis reveals the presence of noncovalent intermolecular S⋅⋅⋅S interactions, which are essential for the spatial arrangement of the molecules. Density functional theory (DFT) calculations including dispersion and damping corrections result in a unit cell volume very close to the value determined experimentally. Thermal decomposition in an inert atmosphere generates black needles with lengths of up to 500 μm. X-ray powder diffraction and pair distribution function analyses demonstrate that the needles are composed of nanosized crystals with a volume-weighted average domain size of 20(1) nm. According to results of X-ray photoemission experiments, the black needles are covered by a nitrogen-rich carbon nitride with composition near (CN)2 N. 13 C solid-state NMR investigations indicate that two different carbon species are present, with signals corresponding well to heptazine units as in melon and triazine units as in poly(triazin imide) type compounds. Scanning transmission electron microscopy tomography evidences that the needles are composed of slightly elongated nanoparticles.

CsTb3STe4 und CsTb5S2Te6: Zwei pseudo-ternäre Caesium-Terbium-Chalkogenide mit geordneten S2−- und Te2−-Anionen

Abstract By the oxidation of terbium metal with sulfur and tellurium in the presence of cesium bromide as flux at 850°C for 10 days, the first quaternary cesium terbium chalcogenides with ordered S2− and Te2− anions could be obtained as main products. The new compounds CsTb3STe4 and CsTb5S2Te6 occur as black needles. While CsTb3STe4 crystallizes in the orthorhombic space group Pnma with a=1924.08(16), b=433.61(3) and c=1493.47(13) pm for Z=4, CsTb5S2Te6 adopts the monoclinic space group C2/m with a=2146.17(18), b=431.42(3), c=1049.68(9) pm and β=102.064(3)° for Z=2. Both crystal structures are characterized by parallel cationic and anionic strands ( { [ STb 3 ] 7 + } ∞ 1 ${}_\infty ^1\{ {[{\rm{ST}}{{\rm{b}}_{\rm{3}}}]^{7 + }}\} $ and { [ CsTe 4 ] 7 − } ∞ 1 ${}_\infty ^1\{ {[{\rm{CsT}}{{\rm{e}}_4}]^{7 - }}\} $ for CsTb3STe4 as well as { [ S 2 Tb 5 ] 11 + } ∞ 1 ${}_\infty ^1\{ {[{{\rm{S}}_{\rm{2}}}{\rm{T}}{{\rm{b}}_{\rm{5}}}{\rm{]}}^{11 + }}\} $ and { [ CsTe 6 ] 11 – } ∞ 1 ${}_\infty ^1\{ {[{\rm{CsT}}{{\rm{e}}_6}]^{11-}}\} $ for CsTb5S2Te6), all running along [010]. The cationic chains result from vertex-connected [STb4]10+ tetrahedra (d(S2−–Tb3+)=271–277 pm), whereas face-sharing bicapped trigonal or square prisms [CsTe6+2]15− or [CsTe8+2]19−, respectively, form their anionic counterparts.

Evaluating Endmember and Band Selection Techniques for Multiple Endmember Spectral Mixture Analysis using Post-Fire Imaging Spectroscopy

Fire impacts many vegetated ecosystems across the world. The severity of a fire is major component in determining post-fire effects, including soil erosion, trace gas emissions, and the trajectory of recovery. In this study, we used imaging spectroscopy data combined with Multiple Endmember Spectral Mixture Analysis (MESMA), a form of spectral mixture analysis that accounts for endmember variability, to map fire severity of the 2013 Rim Fire. We evaluated four endmember selection approaches: Iterative Endmember Selection (IES), count-based within endmember class (In-CoB), Endmember Average Root Mean Squared Error (EAR), and Minimum Average Spectral Angle (MASA). To reduce the dimensionality of the imaging spectroscopy data we used uncorrelated Stable Zone Unmixing (uSZU). Fractional cover maps derived from MESMA were validated using two approaches: (1) manual interpretation of fine spatial resolution WorldView-2 imagery; and (2) ground plots measuring the Geo Composite Burn Index (GeoCBI) and the percentage of co-dominant and dominant trees with green, brown, and black needles. Comparison to reference data demonstrated fairly high correlation for green vegetation and char fractions (r2 values as high as 0.741 for the MESMA ash fractions compared to classified WorldView-2 imagery and as high as 0.841 for green vegetation fractions). The combination of uSZU band selection and In-CoB endmember selection had the best trade-off between accuracy and computational efficiency. This study demonstrated that detailed fire severity retrievals based on imaging spectroscopy can be optimized using techniques that would be viable also in a satellite-based imaging spectrometer.

Defining the window of opportunity for feeding initiation by second-instar spruce budworm larvae

Establishing feeding sites is critical for the survival of neonate Lepidoptera larvae. Rapid foliar quality changes during leaf expansion create a narrow window of opportunity for establishment of early-spring feeders. We examined the effect of phenological synchrony between black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) and balsam fir (Abies balsamea (L.) Mill.) budbreak and spruce budworm (Choristoneura fumiferana (Clemens)) emergence on the feeding behaviour of young larvae and on overall larval growth and survival under laboratory conditions. We correlated these variables with bud development and foliar toughness during the growing season. Our results show that early-emerging second-instar larvae were unable to feed on either black spruce or balsam fir buds; budworm on balsam fir mined old foliage and exhibited good survival and performance, but those on black spruce remained on the foliar surface and suffered high mortality and low growth. In the second later-emerging cohort, bud feeding gradually increased on black spruce whereas it was already the predominant behaviour on balsam fir, and no differences in performance were observed between host species. Thus, black spruce budbreak constitutes a strict window of opportunity, since larvae are often unable to mine the old foliage. Our results suggest that mechanical toughness could be the obstacle preventing young larvae from mining old black spruce needles. Our findings confirm the importance of second-instar ecology in spruce budworm, suggesting that, if climate warming eventually results in an improvement in phenological synchrony between spruce budworm and black spruce, larval survival may increase.

Crystal Structure of Tl2[NbCl6] and Tl2[NbBr6

Single crystals of Tl2[NbCl6] (1) and Tl2 [NbBr6] (2) are obtained as black needles on heating TlCl, Nb, S2Cl2 (1) and Tl, Nb, and Br2 at 400°C (2). Tl2NbBr6 also forms in the reaction of TlBr, Nb, Br2, and S at 500°C. Both compounds crystallize in the K2[PtCl6] structure type to form non-distorted octahedral [NbХ6]2– anions (Nb–Cl 2.397(4) A and Nb–Br 2.516(2) A). The magnetic properties of Tl2[NbBr6] in a range 5-300 K indicate an antiferromagnetic interaction between Nb4+ ion spins (d1, S = 1/2). On cooling, the compound becomes a noncollinear ferromagnet with Tc = 23 K.

No solid solution compounds in between the binaries: syntheses and crystal structures of Nb(Br0.62(4)Cl0.38(4))2Cl2and NbI2Cl2

AbstractThe anion-mixed niobium tetrahalides Nb(Br0.62(4)Cl0.38(4))2Cl2and NbI2Cl2were obtained by heating NbBr5with NbCl5and NbI5with NbCl5, respectively, in equimolar ratios with niobium metal in evacuated, torch-sealed silica ampoules at 720 K for 3 days. The orthorhombic title compounds form as very brittle black needles and were characterized by single-crystal X-ray diffraction [space group:Immm,Z=4;a=704.27(6),b=824.13(7),c=929.64(8) pm for Nb(Br0.62(4)Cl0.38(4))2Cl2anda=753.76(6),b=829.38(7) andc=983.41(8) pm for NbI2Cl2]. Surprisingly enough, these mixed-anionic halides are not isostructural with either NbCl4, NbBr4or NbI4, but crystallize isotypically with TaI2Cl2, thus being examples for differential site occupancy stabilized materials. Structural features of other niobium(IV) halides are compiled and compared to those of Nb(Br0.62(4)Cl0.38(4))2Cl2and NbI2Cl2. Except for NbF4, they all exhibit chains oftrans-edge connected [NbX6]2−octahedra, which allowPeierlsdistortions to form Nb–Nb single bonds. The packing of these chains differ, however, depending on the actual halide or mixed-halide combination.

Ionothermal Syntheses, Crystal Structures, and Chemical Bonding of the Rhodium‐Centered Clusters [RhBi9]4+and [(RhBi7)I8

The first filled Bi95+polycation was isolated in the form of [RhBi9](AlCl4)4crystals by dissolution of the solid precursor Bi12–xRhX13–xin the Lewis‐acidic ionic liquid [BMIm]Cl·3.6AlCl3(BMIm = 1‐butyl‐3‐methylimidazolium) at 140 °C. In the monoclinic crystal structure [P21/n, a= 1217.5(2) pm,b= 1741.6(3) pm,c= 5085.7(7) pm,β= 90.117(8)°], the almost spherical [RhBi9]4+polycations (approximateD3hsymmetry; Rh–Bi 276 ± 3 pm) show pronounced orientational disorder. Shiny black needles of Bi7RhI8were obtained from the reaction of rhodium, bismuth, and BiI3in the ionic liquid [BMIm]Cl·1.3AlCl3at 200 °C. Bi7RhI8[P21/n, a= 943.10(1) pm,b= 1582.40(1) pm,c= 1645.40(1) pm,β= 95.48(1)°] is isostructural to Bi7RhBr8and consists of molecular clusters [(RhBi7)I8]. The rhodium atom centers a pentagonal bipyramid of bismuth atoms, and the two apical bismuth atoms are in square‐planar coordination of iodide ions. DFT‐based calculations indicate strong bismuth‐rhodium bonding with predominantly covalent character for both clusters. The electronic structure of the Bi95+cage is notably modified by this interaction, but the characteristic bonding features of the host cluster with theD3hconfiguration are still maintained. In Bi7RhI8, on the other hand, bonding is dictated by the spatial distribution of mutually repelling iodine atoms, and the Bi–Rh bonding is highly polar.

How to Become a Forest Ecologist In Only 40 Years

When I was 12 years old, my mother took me to the public library where I had to check out at least one book every week. John T. Curtis’ great classic The Vegetation of Wisconsin, an Ordination of Plant Communities (1959) was on the shelf. Despite my lack of appreciation for the words “plant community” and “ordination.” I checked out the book. According to the index it mentioned Wisconsin’s Door Peninsula, where our family summer house was located, and I might learn about the surrounding forests. Surprisingly, I was engrossed in the book, read it cover to cover, memorized the plant species in every native plant community, and within a few weeks decided to carry on the type of work Curtis had started, and set the personal goal of obtaining a Ph.D. in Forest Ecology at Curtis’ university, The University of Wisconsin-Madison. While a senior undergraduate student in Botany and Bacteriology at UW-Madison, I noticed Craig Lorimer’s newly published paper on reconstructing disturbance history of forest stands from tree-ring analysis (Lorimer 1980). Out of the blue one day I stopped by his office and suggested a Ph.D. project to examine disturbance history of many stands across a large landscape in Upper Michigan’s Porcupine Mountains Wilderness State Park, with its 35,000 acres of old-growth hemlock and sugar maple forests. We agreed that this was a worthy project, and after five summers of field work, we produced several papers with new methods for analyzing disturbance history and applied these methods to obtain recurrence intervals for treefall (mostly wind) disturbances across a gradient of severities (Frelich and Lorimer 1989, 1991). The next step in my career resulted from attending the 1987 ESA Annual Meeting in Columbus, Ohio, where I met with prominent paleoecologist Margaret B. Davis (who was ESA President that year). Margaret had illuminated the development of forest communities during the Holocene by using fossil pollen analyses across eastern North America to show that each tree species migrated independently in response to climate change, and that the tree community in any one place was a temporary phenomenon, perhaps the best demonstration of the individualistic nature of plant communities (Davis 1981). I moved to the University of Minnesota for a post doc with Margaret to examine in detail how the unlogged hemlock and maple forests where I had done my Ph.D. field work formed and maintained alternate communities on very similar sites due to neighborhood effects (Frelich et al. 1993). A highlight was dating fossil black spruce needles from the bottom of Lee’s hollow at ~9700 years before present; boreal spruce gave way to jack pine, then oak and white pine, and finally a patchy mosaic of hemlock and maple as the climate warmed and then slightly cooled over the ensuing 9000 years. Living in Minnesota, I finally was able to visit the primeval rock-bound forests of northern Minnesota, after many years of studying the classic work of Heinselman (1973, 1981), which showed how fires and succession (or oftentimes a lack of succession) created a landscape mosaic in the boreal forests of Minnesota’s Boundary Waters Canoe Area Wilderness. I was able to spend a few days canoeing with Heinselman before he died in 1993, enough to get the necessary ideas to build on his published work and launch a major, 20-year effort to understand fire and wind disturbance in collaboration with Peter Reich (e.g., Reich et al. 2001).

Condensed Double‐Chain Cluster Complexes with Seven‐Coordinate Endohedral Iridium Atoms in {Ir2Gd5}Br5

AbstractAbstract. The new condensed double‐chain cluster complex compound {Ir2Gd5}Br5 was obtained from a reaction of GdBr3 with metallic gadolinium and iridium at elevated temperatures. The thin black needles crystallize with the orthorhombic crystal system, space group Pnma(no. 62); a = 1255.4(1) pm, b = 414.05(3) pm, c = 2633.8(3) pm,Z = 4, R1/wR2 = 0.0504/0.0346 for all data. Monocapped trigonal prisms of gadolinium atoms with endohedral iridium atoms are connected by common rectangular faces to chains and further by edges to double chains, which form a herringbone arrangement. The double chains are coordinated by bromido ligands and are connected in accord with the formulation {Ir2Gd5}Br4/2iBr2/3i(e)Br1/3i(f)Br2/2i–i(e/f)Br1/2i–aBr1/2a–i.

Ser oficial combatente do Exército: uma delegação transgeracional?

Esta pesquisa teve como objetivo geral investigar a influência exercida pelo pai, oficial do exército, na decisão do filho para seguir a carreira militar e como este último percebe a referida carreira. Especificamente, procurou-se analisar as motivações que levaram à escolha pela carreira por parte dos filhos; os ganhos obtidos e as dificuldades para exercer a carreira; o papel da família e as expectativas acerca do futuro. A pesquisa foi realizada com 20 cadetes alunos da Academia Militar das Agulhas Negras, que responderam a uma entrevista analisada de acordo com a técnica da análise de conteúdo temática. Os resultados apontaram a forte influência do pai, o apoio da família, além da convivência diária com a rotina e as normas da instituição como as principais motivações para a escolha da carreira. O sentimento de orgulho e de honra perpassara todas as entrevistas, embora os participantes tenham reconhecido ser uma carreira caracterizada por perdas, sacrifícios e esforço constante. As expectativas de futuro remetem ao desejo de contínua dedicação para melhorar o desempenho e as colocações, bem como a construção de uma família.

ChemInform Abstract: Pentavalent and Tetravalent Uranium Selenides, Tl3Cu4USe6 and Tl2Ag2USe4: Syntheses, Characterization, and Structural Comparison to Other Layered Actinide Chalcogenide Compounds.

AbstractGolden black single crystals of Tl3Cu4USe6 and long black needles of Tl2Ag2USe4 are prepared by reaction of the elements in excess TlCl at 1123 K for 7 d (yield 10 and 20 wt.%, resp.).

Local and Permeating Disorder of Copper(I) Cations in Cu3BiS2Br2 and Cu4Bi3S5Br3–xClx (x = 1.19)

AbstractMelting reactions of Bi2S3, CuX (X = Cl, Br), copper, and sulfur resulted in black needles of qua‐ and quinternary copper bismuth sulfide halogenides. Cu3BiS2Br2 (I) has a melting point of 638(5) K and crystallizes in the orthorhombic space group Pnma with a = 804.50(6) pm, b = 393.27(3) pm, and c = 2253.2(2) pm at T = 293(2) K. Cu4Bi3S5Br3–xClx (x = 1.19(2)) (II) crystallizes in the monoclinic space group I2/m with lattice parameters a = 1573.7(2) pm, b = 397.52(3) pm, c = 2164.9(3) pm, and β = 95.66(1) °. Both compounds exhibit networks of thio‐halogenido‐bismuthate(III) polyhedra that join corners, edges, and faces. The copper(I) cations are spread over numerous contiguous trigonal or tetrahedral voids. In case of (II) a continuous pathway for copper ion transport along [010] is formed. The pseudo‐potential barrier for hopping of copper ions was calculated as 30 meV only.

Extended Occupational and Positional Disorder in Pavonite Homologous Copper Bismuth Chalcogenide Halogenides

AbstractMelting reactions of CuBr, BiBr3 and Bi2Q3 (Q = S or Se) resulted in black needles of quaternary chalcogenide bromides. Cu1.5Bi2.64S3.42Br2.58 has a melting point of 708(5) K and crystallizes in the monoclinic space group C2/m with a = 1315.1(3) pm, b = 410.28(5) pm, c = 937.2(2) pm, β = 90.33(2)° at T = 293(2) K. The isostructural selenide Cu1.57Bi2.37Se2.68Br3.32, which melts at 724(5) K, has the lattice parameters a = 1353.9(3) pm, b = 417.54(5) pm, c = 960.4(2) pm, β = 91.13(2)°. Black needles of the selenide iodides Cu1.57Bi4.69Se7.64I0.36 and Cu2.31Bi5Se8.31I0.69 were obtained by chemical vapor transport of CuI and Bi2Se3. They also crystallize in space group type C2/m with a = 1373.9(4) pm, b = 417.4(1) pm, c = 1464.6(4) pm, β = 115.57(2)°, and a = 1369.1(3) pm, b = 416.6(1) pm, c = 1526.4(3) pm, β = 99.81(3)°, respectively. All four compounds belong to pavonite homologous series. Their structures are built up of two alternating types of layered modules parallel (001), denoted A and B. Composition and shape of module A are almost the same in all structures. They consist of paired rods $\rm ^1_\infty[BiQ_{3/3}X_{2/2}Z_{2/2}]$ = Br, I) running along [010] and copper(I) cations that are distributed over various voids between the rods. Modules of type B are composed of [MZ6] octahedra (M = Bi/Cu), which are arranged in NaCl‐type fragments of thickness N = 1, 3 or 4. The Joint Probability Density Function (JPDF) reveals a continuous pathway for copper ion transport along [010] in the case of the sulfide bromide. The pseudo‐potential for hopping of copper ions was calculated as 47 meV only. The electrical and thermal conductivities as well as the Seebeck coefficient were determined to evaluate the thermoelectric properties.

Trace-element, rare-earth element and boron isotopic compositions of tourmaline from a vein-type Pb–Zn–Cu ± U deposit, NE Turkey

This paper reports trace-element, rare-earth element (REE) and boron isotopic compositions of tourmaline in the Asarcık granitoid and quartz veins at Şebinkarahisar. Abundant tourmaline occurs in the vein-type Pb–Zn–Cu ± U deposit, within the northeastern Pontide Metallogenic Belt, both within the Late Cretaceous Asarcık granitoid and in associated quartz–tourmaline veins. Tourmaline in the granitoid forms as rosettes up to 1.5 cm in diameter, whereas in quartz–tourmaline veins a few centimetres to a few metres wide, it occurs as black needles and masses that cut the pluton. We present a systematic geochemical study of these tourmalines – all of the schorl-dravite series. Tourmalines from the quartz veins contain high concentrations of ore metals such as Ag, Bi and Zn and have higher Sr, Cr and Sn contents than tourmalines in the Asarcık granitoid. Tourmalines from intensively altered parts of the pluton are characterized by higher concentrations of trace elements such as Ba, Rb, V, Sc, Th and Zr compared with occurrences in the quartz veins and in the fresh and less-altered granitoid. Chondrite-normalized patterns of REEs in tourmalines from the Asarcık granitoid are generally similar to those of tourmalines in the quartz veins. All vein tourmalines, however, are characterized by heavy REE enrichments, in sharp contrast to those in the granitoid. Boron isotopic compositions of tourmalines range from − 14.0 to − 2.2‰ and fall within the δ11B range of this mineral in granite-related settings. Tourmaline rosettes from the Asarcık granitoid show relatively lighter δ11B values ( − 14.0 to − 12.2‰) in comparison with those in the quartz veins ( − 10.4 to − 2.2‰).

Cs2Gd6N2Te7: The First Quaternary Nitride Telluride of the Lanthanides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis and crystal structure of Mg 2B 24C, a new boron-rich boride related to “tetragonal boron I”

Single crystals of Mg 2B 24C, a new boron-rich boridecarbide of magnesium, were synthesized as black needles and columns by reaction of the elements in Ta ampoules and BN crucibles at 1300 °C. The crystal structure was determined by X-ray diffraction ( P-4 n2, a = 8.9391 ( 13 ) Å , c = 5.0745 ( 10 ) Å , Z = 2 , 713 reflections, 64 variables, R 1 ( F ) = 0.0235 , w R 2 ( I ) = 0.0591 ). It is closely related to “tetragonal boron I” and can be described as a tetragonal rod packing of corner-linked B 12 icosahedra with C and Mg atoms in the voids. Each B 12 icosahedron has 2 B–C bonds and 10 exohedral bonds to other icosahedra, 2 within the rod and 4×2 to neighbouring rods. The isolated C atoms are 4-fold coordinated forming distorted tetrahedra. Mg is placed on two crystallographically independent positions within the three-dimensional B 12C network. Mg 2B 24C is the first example for a compound related to “tetragonal boron I” with a stoichiometric composition.