6 research outputs found
Оценка экологической опасности рассеивания газопылевого облака при массовых взрывах в карьерах
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties
Conductive Lewis Base Matrix to Recover the Missing Link of Li<sub>2</sub>S<sub>8</sub> during the Sulfur Redox Cycle in Li–S Battery
Sulfur and polysulfides play important
roles on the environment
and energy storage systems, especially in the recent hot area of high
energy density of lithium–sulfur (Li–S) batteries. However,
the further development of Li–S battery is still retarded by
the lack of complete mechanistic understanding of the sulfur redox
process. Herein we introduce a conductive Lewis base matrix which
has the ability to enhance the battery performance of Li–S
battery, via the understanding of the complicated sulfur redox chemistry
on the electrolyte/carbon interface by a combined in operando Raman
spectroscopy and density functional theory (DFT) method. The higher
polysulfides, Li<sub>2</sub>S<sub>8</sub>, is found to be missing
during the whole redox route, whereas the charging process of Li–S
battery is ended up with the Li<sub>2</sub>S<sub>6</sub>. DFT calculations
reveal that Li<sub>2</sub>S<sub>8</sub> accepts electrons more readily
than S<sub>8</sub> and Li<sub>2</sub>S<sub>6</sub> so that it is thermodynamically
and kinetically unstable. Meanwhile, the poor adsorption behavior
of Li<sub>2</sub>S<sub><i>n</i></sub> on carbon surface
further prevents the oxidization of Li<sub>2</sub>S<sub><i>n</i></sub> back to S<sub>8</sub> upon charging. Periodic DFT calculations
show that the N-doped carbon surface can serve as conductive Lewis
base “catalyst” matrix to enhance the adsorption energy
of Li<sub>2</sub>S<sub><i>n</i></sub> (<i>n</i> = 4–8). This approach allows the higher Li<sub>2</sub>S<sub><i>n</i></sub> to be further oxidized into S<sub>8</sub>, which is also confirmed by in operando Raman spectroscopy. By recovering
the missing link of Li<sub>2</sub>S<sub>8</sub> in the whole redox
route, a significant improvement of the S utilization and cycle stability
even at a high sulfur loading (70%, m/m) in the composite on a simple
super P carbon
Self-Sorting of Heteroanions in the Assembly of Cross-Shaped Polyoxometalate Clusters
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties
Self-Sorting of Heteroanions in the Assembly of Cross-Shaped Polyoxometalate Clusters
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties
Additional file 2: of DNMT3A and TET1 cooperate to regulate promoter epigenetic landscapes in mouse embryonic stem cells
Table S1. List of oligonucleotides: guide sgRNAs and primers. (PDF 52 Kb
Additional file 1: of DNMT3A and TET1 cooperate to regulate promoter epigenetic landscapes in mouse embryonic stem cells
Figure S1âS11. Figures and legends for Supplementary Figures S1âS11. (PDF 15.6Â Mb