55 research outputs found
Comparative Life Cycle Assessment of Battery Storage Systems for Stationary Applications
This
paper presents a comparative life cycle assessment of cumulative
energy demand (CED) and global warming potential (GWP) of four stationary
battery technologies: lithium-ion, lead-acid, sodiumâsulfur,
and vanadium-redox-flow. The analyses were carried out for a complete
utilization of their cycle life and for six different stationary applications.
Due to its lower CED and GWP impacts, a qualitative analysis of lithium-ion
was carried out to assess the impacts of its process chains on 17
midpoint impact categories using ReCiPe-2008 methodology. It was found
that in general the use stage of batteries dominates their life cycle
impacts significantly. It is therefore misleading to compare the environmental
performance of batteries only on a mass or capacity basis at the manufacturing
outlet (âcradle-to-gate analysesâ) while neglecting
their use stage impacts, especially when they have different characteristic
parameters. Furthermore, the relative ranking of batteries does not
show a significant dependency on the investigated stationary application
scenarios in most cases. Based on the results obtained, the authors
go on to recommend the deployment of batteries with higher round-trip
efficiency, such as lithium-ion, for stationary grid operation in
the first instance
Monovalent Cation-Exchanged Natrolites and Their Behavior under Pressure. A Computational Study
Recently
natrolite was shown to be an auxetic material that is
able to exchange extra-framework Na<sup>+</sup> cations with other
mono-, di-, and trivalent cations. Under pressure up to several GPa,
these cation-exchanged natrolites undergo superhydration and/or phase
transformations in the cationâwater arrangement. Using density
functional theory we studied in silico the ion exchange in natrolites.
First we optimized the structures of Li<sup>+</sup>-, Na<sup>+</sup>-, K<sup>+</sup>-, Rb<sup>+</sup>-, and Cs<sup>+</sup>-exchanged
natrolites at ambient conditions and compared the resulting lattice
energies to that of the hypothetical H-form of natrolite. Of all natrolites,
the smallest formal exchange energy was found for Na-NAT, in agreement
with the natural occurrence of this material. Then we modeled the
effect of pressure on Na-, Rb-, and Cs-natrolites, addressing (<i>i</i>) the incorporation of water ligands into the zeolite framework,
accompanied by an increase in volume; and (<i>ii</i>) the
changes in the cationâwater arrangement within the zeolite
pores. The computational models reproduce reasonably well the critical
pressure, at which these phenomena occur, and, in the case of Cs-NAT,
point toward a cation displacement model for its structural transition
under pressure
Monovalent Cation-Exchanged Natrolites and Their Behavior under Pressure. A Computational Study
Recently
natrolite was shown to be an auxetic material that is
able to exchange extra-framework Na<sup>+</sup> cations with other
mono-, di-, and trivalent cations. Under pressure up to several GPa,
these cation-exchanged natrolites undergo superhydration and/or phase
transformations in the cationâwater arrangement. Using density
functional theory we studied in silico the ion exchange in natrolites.
First we optimized the structures of Li<sup>+</sup>-, Na<sup>+</sup>-, K<sup>+</sup>-, Rb<sup>+</sup>-, and Cs<sup>+</sup>-exchanged
natrolites at ambient conditions and compared the resulting lattice
energies to that of the hypothetical H-form of natrolite. Of all natrolites,
the smallest formal exchange energy was found for Na-NAT, in agreement
with the natural occurrence of this material. Then we modeled the
effect of pressure on Na-, Rb-, and Cs-natrolites, addressing (<i>i</i>) the incorporation of water ligands into the zeolite framework,
accompanied by an increase in volume; and (<i>ii</i>) the
changes in the cationâwater arrangement within the zeolite
pores. The computational models reproduce reasonably well the critical
pressure, at which these phenomena occur, and, in the case of Cs-NAT,
point toward a cation displacement model for its structural transition
under pressure
Potassium-Exchanged Natrolite Under Pressure. Computational Study vs Experiment
Using
density functional theory we modeled the effects of pressure on K-exchanged
natrolite, K-NAT, including superhydration and the experimentally
observed structural phase transition. Natrolites are composed of T<sub>5</sub>O<sub>10</sub> secondary building units (T = Si, Al) linking
two Al- and three Si-based TO<sub>4</sub> tetrahedra which in projection
have an average chain rotation angle Ď with respect to the crystallographic <i>a</i>- and <i>b</i>-axes. Besides an isomer with pore
axes orientations characterized by a negative chain rotation angle,
found experimentally at moderate pressure, we also examined a superhydrated
isomer with pore axes orientations resulting from positive chain rotation
angles in the pressure range 1â2.5 GPa. We estimated the critical
pressure for possible transformations between various isomers, but
we were unable to identify any specific energetic preference for a
superhydrated structure with a negative chain rotation angle. Therefore,
our computational results suggest that both isomers coexist in the
same pressure range and transform into a more compact structure near
4 GPa. We also modeled the pathways for this latter phase transition
and found rather similar barrier heights, 43â44 kJ mol<sup>â1</sup> per K<sup>+</sup> ion for both isomers, but distinct
energy profiles. Thus, based on the modeling results, the isomers
of superhydrated K-NAT, with either positive or negative chain rotation
angles, may coexist at moderate pressures, calling for new experiments
HPV-47-Induced and Tattoo-associated Verrucae Planae: Report of a Case and Review of the Literature
<p><b>Article full text</b></p>
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<p>The full text of this article can
be found here<b>. </b><a href="https://link.springer.com/article/10.1007/s13555-017-0197-y">https://link.springer.com/article/10.1007/s13555-017-0197-y</a></p><p></p>
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A Slowly Growing Orange Patch on the Cheek: Diagnosis of Lupus Vulgaris 20 Years After Onset of First Skin Changes
<p><b>Article full text</b></p>
<p><br></p>
<p>The full text of this article can
be found here<b>. </b><a href="https://link.springer.com/article/10.1007/s13555-016-0158-x">https://link.springer.com/article/10.1007/s13555-016-0158-x</a></p><p></p>
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<p><b>Provide enhanced content for this
article</b></p>
<p><br></p>
<p>If you are an author of this
publication and would like to provide additional enhanced content for your
article then please contact <a href="http://www.medengine.com/Redeem/âÂÂmailto:[email protected]âÂÂ"><b>[email protected]</b></a>.</p>
<p><br></p>
<p>The journal offers a range of
additional features designed to increase visibility and readership. All
features will be thoroughly peer reviewed to ensure the content is of the
highest scientific standard and all features are marked as âpeer reviewedâ to
ensure readers are aware that the content has been reviewed to the same level
as the articles they are being presented alongside. Moreover, all sponsorship
and disclosure information is included to provide complete transparency and
adherence to good publication practices. This ensures that however the content
is reached the reader has a full understanding of its origin. No fees are
charged for hosting additional open access content.</p>
<p><br></p>
<p>Other enhanced features include,
but are not limited to:</p>
<p><br></p>
<p>⢠Slide decks</p>
<p>⢠Videos and animations</p>
<p>⢠Audio abstracts</p>
<p>⢠Audio slides</p
High-Pressure Chemistry of a Zeolitic Imidazolate Framework Compound in the Presence of Different Fluids
Pressure-dependent structural and
chemical changes of the zeolitic
imidÂazolate framework compound ZIF-8 have been investigated
using different pressure transmitting media (PTM) up to 4 GPa. The
unit cell of ZIF-8 expands and contracts under hydrostatic pressure
depending on the solvent molecules used as PTM. When pressurized in
water up to 2.2(1) GPa, the unit cell of ZIF-8 reveals a gradual contraction.
In contrast, when alcohols are used as PTM, the ZIF-8 unit cell volume
initially expands by 1.2% up to 0.3(1) GPa in methanol, and by 1.7%
up to 0.6(1) GPa in ethanol. Further pressure increase then leads
to a discontinuous second volume expansion by 1.9% at 1.4(1) GPa in
methanol and by 0.3% at 2.3(1) GPa in ethanol. The continuous uptake
of molecules under pressure, modeled by the residual electron density
derived from Rietveld refinements of X-ray powder diffraction, reveals
a saturation pressure near 2 GPa. In non-penetrating PTM (silicone
oil), ZIF-8 becomes amorphous at 0.9(1) GPa. The structural changes
observed in the ZIF-8-PTM system under pressure point to distinct
molecular interactions within the pores
Direct Determination of Sulfur Species in Coals from the Argonne Premium Sample Program by Solid Sampling Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry
A new
direct solid sampling method for speciation of sulfur in
coals by electrothermal vaporization inductively coupled plasma optical
emission spectrometry (ETV-ICP OES) is presented. On the basis of
the controlled thermal decomposition of coal in an argon atmosphere,
it is possible to determine the different sulfur species in addition
to elemental sulfur in coals. For the assignment of the obtained peaks
from the sulfur transient emission signal, several analytical techniques
(reflected light microscopy, scanning electron microscopy with energy
dispersive X-ray spectroscopy and X-ray diffraction) were used. The
developed direct solid sampling method enables a good accuracy (relative
standard deviation ⤠6%), precision and was applied to determine
the sulfur forms in the Argonne premium coals, varying in rank. The
generated method is time- and cost-effective and well suited for the
fast characterization of sulfur species in coal. It can be automated
to a large extent and is applicable for process-accompanying analyses
Two-Step Pressure-Induced Superhydration in Small Pore Natrolite with Divalent Extra-Framework Cations
In
situ high pressure X-ray powder diffraction studies of natrolite
(NAT) containing the divalent extra-framework cations (EFC) Sr<sup>2+</sup>, Ca<sup>2+</sup>, Pb<sup>2+</sup>, and Cd<sup>2+</sup> reveal
that they can be superhydrated in the presence of water. In the case
of Ca-NAT, Sr-NAT, and Pb-NAT pressure-induced hydration (PIH) inserts
40 H<sub>2</sub>O/unit cell into the zeolite compared to 32 in superhydrated
natrolites containing monovalent EFC. Cd-NAT is superhydrated in one
step to a zeolite containing 32 H<sub>2</sub>O/unit cell. PIH of Ca-NAT
and Sr-NAT occurs in two steps. During PIH of Pb-NAT three distinct
steps have been observed. The excess H<sub>2</sub>O in natrolites
with divalent EFC are accommodated on sites no longer required for
charge compensation. Two distinct families with ordered and disordered
EFCâwater topologies have been found. Our work established
the importance of both size and charge of the EFC in PIH
Serum 25(OH)D concentrations are associated with survival of melanoma patients.
<p>When dividing the cohort of melanoma patients according to their serum 25(OH)D concentrations into quartiles, a significant difference in survival from time of diagnosis between the 1<sup>st</sup> (lowest serum 25(OH)D concentrations; 4â9.86 ng/ml) and 4<sup>th</sup> (highest serum 25(OH)D concentrations; 24.4â59.6 ng/ml) quartiles is found (pâ=â0.049). Kaplan-Meier analysis shows a median OS of melanoma patients in the 1<sup>st</sup> quartile (nâ=â81) of 80 months, while in contrast patients in the 4<sup>th</sup> quartile (nâ=â81) have a median OS of 195 months. Age at time of venipuncture has no significant influence on OS (pâ=â0.2). Tumor stage has a significant influence on OS with p-values<10<sup>â3</sup> and 0.002 for tumor stages 4 and 3, respectively. This finding may be due to a dependence of tumor stage on 25(OH)D level (3a). Comparing the survival of melanoma patients venipunctured in winter (Nov-Jan) (nâ=â57) and summer (May-Jul) (nâ=â92) with each other, no significant difference is observed. The median survival in the winter cohort is 62 months as compared to 57 months in the summer cohort (nâ=â149; pâ=â0.056) (3b). The female gender (195 month, nâ=â150) has a significant longer OS compared to the male gender (141 month, nâ=â174) (pâ=â0.003) (3c).</p
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