High-pressure Synthesis and Characterization of the Alkali Metal Borate HP-RbB3O5

The rubidium triborate HP-RbB3O5 (HP=high-pressure) was synthesized under highpressure =high-temperature conditions of 6 GPa and 1000° C in a Walker-type multianvil apparatus. The precursor was gained from a mixture of rubidium carbonate Rb2CO3 and boric acid H3BO3 heated at 850 °C under normal pressure conditions. The single-crystal structure determination showed that HP-RbB3O5 is isotypic to HP-KB3O5, crystallizing monoclinically with eight formula units in the space group C2/c possessing the lattice parameters a=982.3(2), b=885.9(2), c=919.9(2) pm, and β = 104:0(1)°. The boron-oxygen framework consists of trigonal-planar BO3 groups as well as corner- and edge-sharing BO4 tetrahedra that are connected to a three-dimensional framework. Therein, the rubidium cations are surrounded by 10 oxygen anions. IR- and Raman-spectroscopic investigations were performed on single crystals of the compound.

High-pressure Synthesis and Crystal Structure of the Vanadium Orthoborate VBO3

The vanadium orthoborate VBO3 was synthesized under high-pressure / high-temperature conditions of 7.5 GPa and 1250 °C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single crystal X-ray diffraction data, collected at r. t. The title compound crystallizes in the trigonal calcite structure, space group R3̄c, with the lattice parameters a = 462.0(1) and c = 1450.9(3) pm. Within the trigonal planar BO3 groups, the B-O distance is 138.8(3) pm. The vanadium atoms have a slightly distorted octahedral oxygen coordination (V-O: 202.3(2) pm).

Synthesis and Characterization of the Manganese Borate α-MnB2O4

The high-pressure manganese borate α-MnB2O4 was synthesized under high-pressure/hightemperature conditions of 6.5 GPa and 1100 ◦C in a modified Walker-type multianvil apparatus. The monoclinic compound is isotypic to α-FeB2O4, CaAl2O4-II, CaGa2O4, andβ -SrGa2O4 crystallizing with eight formula units in the space group P21/c (Z = 8) with the lattice parameters a = 712.1(2), b = 747.1(2), c = 878.8(2) pm, β = 94.1(1)◦, V = 0.466(1) nm3, R1 = 0.0326, and wR2 = 0.0652 (all data). The compound is built up from layers of “sechser” rings of corner-sharing BO4 tetrahedra that are interconnected to a three-dimensional network. The manganese ions are coordinated by seven oxygen atoms and situated in channels along the a axis.

β-CaB4O7: A New Polymorph Synthesized under High-Pressure/High-Temperature Conditions

A new oxoborate β -CaB4O7 has been synthesized under high-pressure/high-temperature conditions from calcium oxide and boron oxide with a Walker-type multianvil apparatus at 7.7 GPa and 1100 °C. Single crystal X-ray structure determination of β -CaB4O7 revealed: Pmn21, a = 1058.4(1), b = 436.9(1), c = 419.4(1) pm, Z = 2, R1 = 0.0305, wR2 = 0.0587 (all data). The compound is isotypic to the known oxoborates SrB4O7, PbB4O7, and EuB4O7 exhibiting a network structure of linked BO4 tetrahedra. As a prominent feature of the tetrahedral network an oxygen atom is coordinated to three boron atoms. The relation of the crystal structure of the high-pressure phase β -CaB4O7 to the normalpressure phase α-CaB4O7 as well as the relation to the isotypic phases MB4O7 (M = Sr, Pb, Eu) are discussed. The results of IR-spectroscopic investigations on β -CaB4O7 are also presented.

Multianvil High-Pressure Synthesis And Crystal Structure Of β-YbBO3

β-Ytterbium borate (β-YbBO3) was synthesized under high-pressure in a Walker-type multianvil apparatus at 2.2 GPa and 1400 °C. The title-compound crystallizes in the trigonal calcite structure, space group R3̄̄c. Single crystal X-ray data yielded a = 492.1(2), c = 1630.5(9) pm, wR2 = 0.0344 for 165 F2 values and 11 variable parameters. Within the trigonal planar BO3 groups the B-O distance is 137.8(4) pm. The ytterbium atoms have a slightly distorted octahedral oxygen coordination (Yb-O: 224.4(2) pm)

Prevalence of antibodies against influenza A and B viruses in children in Germany, 2008 to 2010

The prevalence of influenza A and B virus-specific IgG was determined in sera taken between 2008 and 2010 from 1,665 children aged 0-17 years and 400 blood donors in Germany. ELISA on the basis of whole virus antigens was applied. Nearly all children aged nine years and older had antibodies against influenza A. In contrast, 40% of children aged 0-4 years did not have any influenza A virus-specific IgG antibodies. Eightysix percent of 0-6 year-olds, 47% of 7-12 year-olds and 20% of 13-17 year-olds were serologically naïve to influenza B viruses. By the age of 18 years, influenza B seroprevalence reached approximately 90%. There were obvious regional differences in the seroprevalence of influenza B in Germany. In conclusion, seroprevalences of influenza A and influenza B increase gradually during childhood. The majority of children older than eight years have basal immunity to influenza A, while comparable immunity against influenza B is only acquired at the age of 18 years. Children aged 0-6 years, showing an overall seroprevalence of 67% for influenza A and of 14% for influenza B, are especially at risk for primary infections during influenza B seasons.

Experimental determinations and quantum-chemical calculations of the vibrational spectra of β-ZnB4O7 and β-CaB4O7

The two oxoborates β-ZnB4O7 and β-CaB4O7 were synthesized and investigated by FTIR- and Raman spectroscopy and ab initio quantum chemical calculations. Maximum and mean deviations between experimentally determined bands and calculated modes ranged between 15-36 cm(-1) and 5-7 cm(-1), respectively, allowing band assignments to vibrational modes in most cases. The complex network structures with tetrahedral BO4 and planar OB3 groups are mirrored by the spectra and numerous vibrational modes, not assignable by standard borates classification schemes. It was confirmed that OB3 units, despite similar force constants and geometry, do not absorb in the same range as BO3 units. Bands in the high wavenumber range are rather caused by B-O-(Zn/Ca), O-B-O, B-O-B, and B-O stretching and bending vibrations. The experimental observation of inactive or Raman-active modes in the absorption spectra indicates defects or structural distortions in both compounds.

High-pressure synthesis and characterization of new actinide borates, AnB4O8 (An=Th, U)

New actinide borates ThB4O8 and UB4O8 were synthesized under high-pressure, high-temperature conditions (5.5 GPa/1100 °C for thorium borate, 10.5 GPa/1100 °C for the isotypic uranium borate) in a Walker-type multianvil apparatus from their corresponding actinide oxide and boron oxide. The crystal structure was determined on basis of single-crystal X-ray diffraction data that were collected at room temperature. Both compounds crystallized in the monoclinic space group C2/c (Z=4). Lattice parameters for ThB4O8: a=1611.3(3), b=419.86(8), c=730.6(2) pm; β=114.70(3)°; V=449.0(2) Å(3); R1=0.0255, wR2=0.0653 (all data). Lattice parameters for UB4O8: a=1589.7(3), b=422.14(8), c=723.4(2) pm; β=114.13(3)°; V=443.1(2) Å(3); R1=0.0227, wR2=0.0372 (all data). The new AnB4O8 (An=Th, U) structure type is constructed from corner-sharing BO4 tetrahedra, which form layers in the bc plane. One of the four independent oxygen atoms is threefold-coordinated. The actinide cations are located between the boron-oxygen layers. In addition to Raman spectroscopic investigations, DFT calculations were performed to support the assignment of the vibrational bands.

Ce4Ag3Ge4O(0.5)--chains of oxygen-centered [OCe2Ce(2/2)] tetrahedra embedded in a [CeAg3Ge4] intermetallic matrix

The oxidation of an intermetallic phase under high-pressure/high-temperature conditions led to the synthesis of Ce4Ag3Ge4O(0.5) exhibiting [OCe2Ce(2/2] tetrahedral chains, in which the oxygen atoms statistically occupy the tetrahedral centres. Starting from a 1:1:1 CeAgGe precursor (NdPtSb type), a multianvil high-pressure/high-temperature experiment at 11.5 GPa and 1250-1300 °C revealed Ce4Ag3Ge4O(0.5), crystallizing in the space group Pnma with the following lattice parameters: a = 2087.3(4), b = 439.9(1), and c = 1113.8(2) pm. Magnetic measurements showed Curie-Weiss behavior above 100 K with an experimental magnetic moment of 2.42 µB per Ce atom, close to the value for the free Ce(3+) ion, clearly indicating trivalent cerium in Ce4Ag3Ge4O(0.5). Full potential GGA+U band structure calculations resulted in metallic properties and a magnetic ground state with one unpaired 4f-electron per cerium in agreement with the experiments.

High-Pressure Synthesis and Characterization of the Actinide Borate Phosphate U2[BO4][PO4]

A new actinide borate phosphate, U2[BO4][PO4], was synthesized in a Walker-type multianvil apparatus at 12.5 GPa and 1000 °C. The crystal structure was determined from single-crystal X-ray diffraction data collected at room temperature. U2[BO4][PO4] crystallizes in the monoclinic space group P21/c with four formula units per unit cell and the lattice parameters a = 854.6(2), b = 775.3(2), c = 816.3(2) pm, and β = 102.52(3)°. The structure consists of double layers of linked uranium-oxygen polyhedra parallel to [100]. The borate tetrahedra are located between the uranium-oxygen layers inside the double layer. The phosphate groups link the double layers.

High-pressure synthesis and characterization of the first cerium fluoride borate CeB2O4F

CeB₂O₄F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO₃]³⁻ groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) ų, R₁=0.0698, and wR₂=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO₃]³⁻ groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed.

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CeB₂O₄F is the first fluoride borate exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO₃]³⁻ groups.

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CeB₂O₄F is the first cerium fluoride borate.

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High-pressure conditions were necessary to synthesize CeB₂O₄F.

One-dimensional Gold Clusters in HP-Ce7Au13+xGe10–x

Single crystals of the high-pressure phase Ce7Au13+xGe10-x were obtained by treating CeAuGe at 9:5 GPa and 1473 - 1523 K in a multi-anvil press. The structure of Ce7Au13:35Ge9:65 was refined on the basis of single-crystal X-ray diffractometer data: new type, Pbam, a = 1571:9(3), b = 1780:3(4), c = 443:58(9) pm, wR2 = 0:0470, 2017 F2 values, 96 variables. Two of the five germanium sites show a small degree of Ge/Au mixing. The gold and germanium atoms build up a complex threedimensional, covalently bonded [Au13:35Ge9:65] network with Au-Ge distances ranging from 249 to 293 pm. The [Au13:35Ge9:65] network also exhibits a one-dimensional gold cluster with Au-Au distances of 275 - 301 pm and a weakly bonded germanium dumb-bell with a Ge4-Ge5 bond length of 271 pm. The four crystallographically independent cerium atoms fill cavities of coordination numbers 19 and 20 within the [Au13:35Ge9:65] network. These coordinations are known from other structure types. Consequently one can describe the Ce7Au13:35Ge9:65 structure as an intergrowth variant of Eu- AuGe, HP-CeAuGe (TiNiSi), CeAu2Ge2 (CePt2Ge2), and Ce3Ag4Ge4 (Gd3Cu4Sn4) related slabs.

High-Pressure Synthesis and Crystal Structure of Ce4B14O27

Ce4B14O27 was synthesized under conditions of 2.6 GPa and 750 °C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single-crystal X-ray diffraction data, collected at room temperature, revealing that Ce4B14O27 is isotypic to La4B14O27. Ce4B14O27 crystallizes monoclinically with four formula units in the space group C2/c (No. 15) and the lattice parameters a = 1117.8(2), b = 640.9(2), c = 2531.7(5) pm, and β = 100.2(1)°. The three-dimensional boron-oxygen framework consists of [BO4]5- tetrahedra and trigonal-planar [BO3]3- groups. The structure contains two crystallographically different cerium ions. Furthermore, Raman spectroscopy was performed on single crystals of Ce4B14O27.

Ce2B8O15: High-pressure synthesis and crystal structure determination of a rare-earth polyborate exhibiting a new “Fundamental Building Block”

The new cerium polyborate Ce

The evidence for the use of growth factors and active skin substitutes for the treatment of non-infected diabetic foot ulcers (DFU): a health technology assessment (HTA)

AIMS

Assessment of the safety, efficacy and effectiveness of growth factors alone or in combination with other technologies in the treatment of DFU including medical, economical, social, ethical and juridical aspects.

METHODS

We systematically searched relevant data bases limited to English and German language and publications since 1990. Review and assessment of the quality of publications followed methods conforming to widely accepted standards for evidence-based medicine and health economics.

RESULTS

We identified 25 studies comparing becaplermin, rhEGF, bFGF and the metabolically active skin grafts Dermagraft and Apligraf with standard wound care (SWC) alone or extracellular wound matrix. Study duration ranged from 12 to 20 weeks and the study population comprised between 17 and 382 patients. Treatment with becaplermin, rhEGF, Dermagraft and Apligraf resulted in a higher incidence of complete wound closure and shorter time to complete wound healing with statistically significant differences. Regarding the proportion of adverse events there was no difference between treatment groups. The methodological quality of the studies was affected by significant deficiencies. Economic evaluations showed becaplermin being cost-effective.

CONCLUSIONS

Add-on therapy with growth factors and active skin substitutes for treating uncomplicated DFU could be an alternative to SWC alone. For explicit recommendations further studies with stronger evidence are necessary.

Multianvil high-pressure / high-temperature synthesis in solid state chemistry

During the last 60 years, new high pressure techniques and their exploitation have permitted the extension of attainable pressure/volume conditions, increased versatility of the apparatus, and hydrostaticity of the attained pressure in a remarkable way. In preparative solid state chemistry, high-pressure/high-temperature synthesis always played a minor role due to technical difficulties and costs. Piston-cylinder and Belt-apparatus both were limited to the working range up to 3 and 10 GPa, respectively. New technical developments, which allow synthesis up to 25 GPa, open up an enormous field of sample synthesis in solid state chemistry. In the following, a short overview on the most important developments in multianvil-techniques is given with respect to their applications for solid state chemistry under high-pressure conditions.

The crystal structure of non-stoichiometric monoclinic Cr5+ x S8 (x = 0.20 and 0.26) prepared under high pressure and high temperature

Two non-stoichiometric chromium rich Cr5+ x S8 (x = 0.20 and 0.26) samples were prepared under high pressure and high temperature conditions. In the crystal structures three different metal atom sites are fully and the fourth site is only partially occupied. The results of single crystal and Rietveld refinements are in good agreement. The CrS6 octahedra share common corners and common faces. Across common faces extraordinary short Cr—Cr distances are observed suggesting metal-to-metal bonding. On the basis of the distortion of the CrS6 octahedra Cr4+ is located on two of the four Cr sites. With increasing Cr content the amount of Cr4+ is lowered and the distortion of two of the four CrS6 octahedra is significantly reduced.

Structure refinements of iron borides Fe2B and FeB

Crystals of the iron borides FeB and Fe2B were obtained from two different high temperature synthesis routes,viz.in combined copper/gallium flux and under high pressure conditions. Their crystal structures were investigated at room and low temperatures. Structure models from the literature were confirmed. The position of the boron atoms was unambiguously determined. FeB (Pnma, no. 62) contains zig-zag chains of boron atoms in which the boron atoms are coordinated by seven iron atoms in the form of a mono-capped trigonal prism. Fe2B (I4/mcm, no. 140) contains single boron atoms in a square antiprismatic iron atom coordination.