12 research outputs found
High-Pressure Synthesis and Characterization of the Ammonium Yttrium Borate (NH<sub>4</sub>)YB<sub>8</sub>O<sub>14</sub>
The
first high-pressure yttrium borate (NH<sub>4</sub>)ÂYB<sub>8</sub>O<sub>14</sub> was synthesized at 12.8 GPa/1300 °C using a Walker-type
multianvil module. The compound crystallizes in the orthorhombic space
group <i>Pnma</i> (no. 62) with the lattice parameters <i>a</i> = 17.6375(9), <i>b</i> = 10.7160(5), and <i>c</i> = 4.2191(2) Ã…. (NH<sub>4</sub>)ÂYB<sub>8</sub>O<sub>14</sub> constitutes a novel structure type but exhibits similarities
to the crystal structure of β-BaB<sub>4</sub>O<sub>7</sub>.
X-ray single-crystal and powder diffraction, EDX, vibrational spectroscopy
as well as quantum chemical calculations were used to characterize
(NH<sub>4</sub>)ÂYB<sub>8</sub>O<sub>14</sub>
The Indium Borate In<sub>19</sub>B<sub>34</sub>O<sub>74</sub>(OH)<sub>11</sub> with T2 Supertetrahedra
The trigonal indium
borate In<sub>19</sub>B<sub>34</sub>O<sub>74</sub>(OH)<sub>11</sub> was synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature
conditions of 13 GPa and 1150 °C. The crystal structure could
be determined by single-crystal X-ray diffraction data collected at
room temperature. In<sub>19</sub>B<sub>34</sub>O<sub>74</sub>(OH)<sub>11</sub> crystallizes in the trigonal space group <i>R</i>3Ì… (Z = 3) with the lattice parameters <i>a</i> =
1802.49(6) pm, <i>c</i> = 1340.46(5) pm, and <i>V</i> = 3.7716(3) nm<sup>3</sup>. The structure of In<sub>19</sub>B<sub>34</sub>O<sub>74</sub>(OH)<sub>11</sub> contains alternating B–O
T2 supertetrahedra units. The presence of hydroxyl groups was confirmed
with vibrational spectroscopic methods such as Raman and IR. Besides
H<sub>2</sub>InB<sub>5</sub>O<sub>10</sub>, In<sub>19</sub>B<sub>34</sub>O<sub>74</sub>(OH)<sub>11</sub> is now the second known compound
in the system In–B–O–H
Synthesis and Characterization of the New Strontium Borogermanate Sr<sub>3–<i>x</i>/2</sub>B<sub>2–<i>x</i></sub>Ge<sub>4+<i>x</i></sub>O<sub>14</sub> (<i>x</i> = 0.32)
The
strontium borogermanate Sr<sub>3–<i>x</i>/2</sub>B<sub>2–<i>x</i></sub>Ge<sub>4+<i>x</i></sub>O<sub>14</sub> (<i>x</i> = 0.32) was synthesized
by high-temperature solid-state reaction of SrO, GeO<sub>2</sub>,
and H<sub>3</sub>BO<sub>3</sub> in a NaF/KF flux system using platinum
crucibles. The structure determination revealed that Sr<sub>3–<i>x</i>/2</sub>B<sub>2–<i>x</i></sub>Ge<sub>4+<i>x</i></sub>O<sub>14</sub> (<i>x</i> = 0.32) crystallizes
in the trigonal space group <i>P</i>321 (No. 150) with the
parameters <i>a</i> = 800.7(2) and <i>c</i> =
488.8(2) pm, with <i>R</i>1 = 0.0281, <i>wR</i>2 = 0.0671 (all data), and <i>Z</i> = 1. The crystal structure
of Sr<sub>3–<i>x</i>/2</sub>B<sub>2–<i>x</i></sub>Ge<sub>4+<i>x</i></sub>O<sub>14</sub> (<i>x</i> = 0.32) consists of distorted SrO<sub>8</sub> cubes, GeO<sub>6</sub> octahedra, GeO<sub>4</sub> tetrahedra, and BO<sub>4</sub> tetrahedra. In addition to the structural investigations, Raman
and IR spectroscopic investigations were carried out
Narrow-Band Red Emission in the Nitridolithoaluminate Sr<sub>4</sub>[LiAl<sub>11</sub>N<sub>14</sub>]:Eu<sup>2+</sup>
The
new narrow-band red-emitting phosphor material Sr<sub>4</sub>[LiAl<sub>11</sub>N<sub>14</sub>]:Eu<sup>2+</sup> was synthesized
by solid-state reaction using a tungsten crucible with a cover plate
in a tube furnace. When excited with blue light (460 nm), it exhibits
red fluorescence with an emission maximum at 670 nm and a full width
at half-maximum of 1880 cm<sup>–1</sup> (∼85 nm). The
crystal structure was solved and refined from single-crystal X-ray
diffraction data. This new compound from the group of the nitridolithoaluminates
crystallizes in the orthorhombic space group <i>Pnnm</i> (No. 58) with the following unit-cell parameters: <i>a</i> = 10.4291(7) Ã…, <i>b</i> = 10.4309(7) Ã…, and <i>c</i> = 3.2349(2) Ã…. Sr<sub>4</sub>[LiAl<sub>11</sub>N<sub>14</sub>]:Eu<sup>2+</sup> shows a pronounced tetragonal pseudo-symmetry.
It consists of a framework of disordered (Al/Li)ÂN<sub>4</sub> and
AlN<sub>4</sub> tetrahedra that are connected to each other by common
corners and edges. Along the [001] direction, the tetrahedral network
creates empty four-membered-ring channels as well as five-membered-ring
channels, in which the Sr<sup>2+</sup> cations are located
Do bacteria shape our development? Crosstalk between intestinal microbiota and HPA axis
Contains fulltext :
179965.pdf (publisher's version ) (Closed access)The human body contains as many bacteria in the intestine as the total number of human body cells. These bacteria have a central position in human health and disease, and would also play a role in the regulation of emotions, behavior, and even higher cognitive functions. The Hypothalamic-Pituitary-Adrenal axis (HPA axis) is a major physiological stress system that produces cortisol. This hormone is involved in responding to environmental stress and also shapes many aspects of brain development. Both the HPA axis and the intestinal microbiota show rapid and profound developmental changes during the first years of life. Early environmental disturbances can affect the development of both systems. Early adversity, for example, is known to lead to later unbalances in both, as well as to psychopathological behavior and emotions. The goal of this theoretical review is to summarize current knowledge on the developmental crosstalk between the intestinal microbiota and the HPA axis, providing a basis for understanding the development and bidirectional communication between these two essential systems in human functioning.14 p
Effects of Gigapascal Level Pressure on Protein Structure and Function
Information on very high pressure (VHP) effects on proteins is limited and therefore effects of VHP on chemistry, structure and function of two model proteins in medical use were studied. VHP (8 GPa) application to l-asparaginase (L-ASNase) resulted in faster mobility on clear native gels. VHP induced generation of lower-MW forms of L-ASNase but VHP treatment did not deteriorate asparaginase activity. Electrophoretic patterns in native and denaturing gels were comparable for untreated and pressurized recombinant human growth hormone (rhGH). rhGH function, however, was deteriorated as shown by a bioassay. In L-ASNase and rhGH a series of protein modifications and amino acid exchanges (indicating cleavage of covalent bonds) were revealed that may probably lead to functional and conformational changes. The findings have implications in protein chemistry, structure, and function and are useful for designing biotechnological applications of protein products
Effects of Gigapascal Level Pressure on Protein Structure and Function
Information on very high pressure (VHP) effects on proteins is limited and therefore effects of VHP on chemistry, structure and function of two model proteins in medical use were studied. VHP (8 GPa) application to l-asparaginase (L-ASNase) resulted in faster mobility on clear native gels. VHP induced generation of lower-MW forms of L-ASNase but VHP treatment did not deteriorate asparaginase activity. Electrophoretic patterns in native and denaturing gels were comparable for untreated and pressurized recombinant human growth hormone (rhGH). rhGH function, however, was deteriorated as shown by a bioassay. In L-ASNase and rhGH a series of protein modifications and amino acid exchanges (indicating cleavage of covalent bonds) were revealed that may probably lead to functional and conformational changes. The findings have implications in protein chemistry, structure, and function and are useful for designing biotechnological applications of protein products
Effects of Gigapascal Level Pressure on Protein Structure and Function
Information on very high pressure (VHP) effects on proteins is limited and therefore effects of VHP on chemistry, structure and function of two model proteins in medical use were studied. VHP (8 GPa) application to l-asparaginase (L-ASNase) resulted in faster mobility on clear native gels. VHP induced generation of lower-MW forms of L-ASNase but VHP treatment did not deteriorate asparaginase activity. Electrophoretic patterns in native and denaturing gels were comparable for untreated and pressurized recombinant human growth hormone (rhGH). rhGH function, however, was deteriorated as shown by a bioassay. In L-ASNase and rhGH a series of protein modifications and amino acid exchanges (indicating cleavage of covalent bonds) were revealed that may probably lead to functional and conformational changes. The findings have implications in protein chemistry, structure, and function and are useful for designing biotechnological applications of protein products
New High-Pressure Gallium Borate Ga<sub>2</sub>B<sub>3</sub>O<sub>7</sub>(OH) with Photocatalytic Activity
The
new high-pressure gallium borate Ga<sub>2</sub>B<sub>3</sub>O<sub>7</sub>(OH) was synthesized in a Walker-type multianvil apparatus
under high-pressure/high-temperature conditions of 10.5 GPa and 700
°C. For the system Ga–B–O–H, it is only
the second known compound next to Ga<sub>9</sub>B<sub>18</sub>O<sub>33</sub>(OH)<sub>15</sub>·H<sub>3</sub>B<sub>3</sub>O<sub>6</sub>·H<sub>3</sub>BO<sub>3</sub>. The crystal structure of Ga<sub>2</sub>B<sub>3</sub>O<sub>7</sub>(OH) was determined by single-crystal
X-ray diffraction data collected at room temperature. Ga<sub>2</sub>B<sub>3</sub>O<sub>7</sub>(OH) crystallizes in the orthorhombic space
group <i>Cmce</i> (<i>Z</i> = 8) with the lattice
parameters <i>a</i> = 1050.7(2) pm, <i>b</i> =
743.6(2) pm, <i>c</i> = 1077.3(2) pm, and <i>V</i> = 0.8417(3) nm<sup>3</sup>. Vibrational spectroscopic methods (Raman
and IR) were performed to confirm the presence of the hydroxyl group.
Furthermore, the band gap of Ga<sub>2</sub>B<sub>3</sub>O<sub>7</sub>(OH) was estimated via quantum-mechanical density functional theory
calculations. These results led to the assumption that our gallium
borate could be a suitable substance to split water photocatalytically,
which was tested experimentally
Structural Redetermination and Photoluminescence Properties of the Niobium Oxyphosphate (NbO)<sub>2</sub>P<sub>4</sub>O<sub>13</sub>
The structure of (NbO)<sub>2</sub>P<sub>4</sub>O<sub>13</sub> was solved and refined based on new single-crystal
diffraction data revealing considerably more complexity than previously
described. (NbO)<sub>2</sub>P<sub>4</sub>O<sub>13</sub> crystallizes
in the triclinic space group <i>P</i>1Ì… with <i>Z</i> = 6. The lattice parameters determined at room temperature
are <i>a</i> = 1066.42(4) pm, <i>b</i> = 1083.09(4)
pm, <i>c</i> = 1560.46(5) pm, α = 98.55(1)°,
β = 95.57(1)°, γ = 102.92(1)°, and <i>V</i> = 1.7213(2) nm<sup>3</sup>. The superstructure contains 64 unique
atoms including two disordered semioccupied oxygen positions. An unusual
180° bond angle between two [P<sub>4</sub>O<sub>13</sub>]<sup>6–</sup> groups was refined to form half-occupied, split positions
in agreement with previous reports. The IR and Raman spectra reflect
the appearance of overlapping bands assignable to specific group vibrations
as well as P–O–P linkages present in the [P<sub>4</sub>O<sub>13</sub>]<sup>6–</sup> entities. Investigation of the
powdered product concerning its photoluminescence properties revealed
an excitability in the UV at 270 nm assigned to O2p–Nb4d charge
transfer transitions. A resulting broad-band emission with the maximum
in the visible region at 455 nm was determined