32 research outputs found
Adsorption and Reaction Branching of Molecular Carbonates on Lithiated C(0001) Substrates
The
desorption and interactions of ethylene carbonate (EC) and dimethyl
carbonate (DMC) with clean and lithiated graphite substrates were
measured by temperature-programmed desorption (TPD) and reaction (TPR)
methods under UHV conditions. Both EC and DMC interact weakly with
the clean C(0001) surface with adsorption energies of 0.60 ±
0.06 and 0.64 ± 0.05 eV, respectively. Addition of Li<sup>+</sup> to the C(0001) substrate significantly increases the binding energies
of molecular carbonates, and the range of measured values is indicative
of EC solvation of lithium ions. EC undergoes complete decomposition
on metallic Li films. Organolithium products were quantified by TPR,
and the amount of lithium carbonate product was determined by detailed
mass balance analysis. Decomposition of 1.5 L of EC resulted in the
formation of 0.64 ± 0.12 L of lithium ethylene dicarbonate, 0.40
± 0.05 L of lithium ethylene glycolate, and 0.5 ± 0.2 L
of lithium carbonate. The branching ratio at the immediate EC–metallic
lithium interface was determined as 70.% organolithium products vs
30% inorganic lithium product
Born–Haber Cycle for Monolayer Self-Assembly at the Liquid–Solid Interface: Assessing the Enthalpic Driving Force
The
driving force for self-assembly is the associated gain in free
energy with decisive contributions from both enthalpy and entropy
differences between final and initial state. For monolayer self-assembly
at the liquid–solid interface, solute molecules are initially
dissolved in the liquid phase and then become incorporated into an
adsorbed monolayer. In this work, we present an adapted Born–Haber
cycle for obtaining precise enthalpy values for self-assembly at the
liquid–solid interface, a key ingredient for a profound thermodynamic
understanding of this process. By choosing terephthalic acid as a
model system, it is demonstrated that all required enthalpy differences
between well-defined reference states can be independently and consistently
assessed by both experimental and theoretical methods, giving in the
end a reliable value of the overall enthalpy gain for self-assembly
of interfacial monolayers. A quantitative comparison of enthalpy gain
and entropy cost reveals essential contributions from solvation and
dewetting, which lower the entropic cost and render monolayer self-assembly
a thermodynamically favored process
Characterizing the Interactions of Dimethyl Sulfoxide with Water: A Rotational Spectroscopy Study
The interaction of
dimethyl sulfoxide with water has been investigated
by Fourier-transform microwave spectroscopy of the 1:1 complex and
its isotopologues, complemented with quantum chemical calculations.
The rotational spectra of 34S and 13C isotopologues
in natural abundance and the H218O and deuterated
water enriched isotopologues have been measured, allowing a partial
structure determination and establishing the position of water in
the complex. In the most stable conformation water was found to be
the donor of a primary OH···OS bond to the oxygen atom
of dimethyl sulfoxide and acceptor of two weak CH···OH
bonds with the methyl hydrogen atoms of dimethyl sulfoxide. From the
structural determination confirmed by quantum chemical calculations,
the water molecule lies in the symmetry plane of dimethyl sulfoxide,
and the complex has an overall Cs symmetry. The experimental findings are supported by atoms
in molecules and symmetry-adapted perturbation theories, which allowed
for determining the hydrogen bond and intermolecular interaction energies,
respectively
Solvent-Dependent Stabilization of Metastable Monolayer Polymorphs at the Liquid–Solid Interface
Self-assembly of 1,3,5-tris(4′-biphenyl-4″-carbonitrile)benzene monolayers was studied at the liquid–solid interface by scanning tunneling microscopy. Application of different fatty acid homologues as solvents revealed a solvent-induced polymorphism. Yet, tempering triggered irreversible phase transitions of the initially self-assembled monolayers, thereby indicating their metastability. Interestingly, in either case, the same thermodynamically more stable and more densely packed monolayer polymorph was obtained after thermal treatment, irrespective of the initial structure. Again, the same densely packed structure was obtained in complementary solvent-free experiments conducted under ultrahigh vacuum conditions. Thus, self-assembly of metastable polymorphs at room temperature is explained by adsorption of partially solvated species under kinetic control. The irreversible phase transitions are induced by thermal desolvation, that is, desorption of coadsorbed solvent molecules
Data_Sheet_1_Enhancement effects of mangrove restoration on blue carbon storage in Qinzhou Bay.doc
IntroductionMangroves are the main carbon sinks in tropical regions and have high capabilities for carbon sequestration. Protection and restoration of mangroves are necessary to reduce carbon emissions and fight climate change. While the Qinzhou Bay as the main area of national mangrove restoration plan in the future, studies on its carbon pools, especially assessment of the carbon sink enhancement effect of restored mangroves along forest chronosequence, are lacking.MethodsThis study aimed to quantify the changes in restored mangrove soil carbon stock, vegetation and root carbon stocks along the forest age sequence in Qinzhou Bay through field survey.ResultsThe results revealed that the carbon stocks of vegetation and roots significantly increased with the developing forest age. Only in the soil layer above 30 cm, the soil carbon storage apparently increased with the developing forest age in non-cofferdam area, and then decreased slowly after reaching the peak (at 6 ~ 8 years). Moreover, the soil carbon storage of mangroves was greater in the cofferdam area than in the non-cofferdam area.DiscussionThis implied that the cofferdam restoration efforts may be more effective in enhancing blue carbon storage, during the initial stages of the restoration process. The results of this study suggested that mangrove restoration has substantial potential capacity in carbon storage and nutrient cycling, providing a reference for the protection and restoration efforts concerning mangroves.</p
Size-Tunable and Monodisperse Tm<sup>3+</sup>/Gd<sup>3+</sup>-Doped Hexagonal NaYbF<sub>4</sub> Nanoparticles with Engineered Efficient Near Infrared-to-Near Infrared Upconversion for In Vivo Imaging
Hexagonal NaYbF<sub>4</sub>:Tm<sup>3+</sup> upconversion nanoparticles hold promise for use in high
contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and
in vivo bioimaging. However, significant hurdles remain in their preparation
and control of their morphology and size, as well as in enhancement
of their upconversion efficiency. Here, we describe a systematic approach
to produce highly controlled hexagonal NaYbF<sub>4</sub>:Tm<sup>3+</sup> nanoparticles with superior upconversion. We found that doping appropriate
concentrations of trivalent gadolinium (Gd<sup>3+</sup>) can convert
NaYbF<sub>4</sub>:Tm<sup>3+</sup> 0.5% nanoparticles with cubic phase
and irregular shape into highly monodisperse NaYbF<sub>4</sub>:Tm<sup>3+</sup> 0.5% nanoplates or nanospheres in a pure hexagonal-phase
and of tunable size. The intensity and the lifetime of the upconverted
NIR luminescence at 800 nm exhibit a direct dependence on the size
distribution of the resulting nanoparticles, being ascribed to the
varied surface-to-volume ratios determined by the different nanoparticle
size. Epitaxial growth of a thin NaYF<sub>4</sub> shell layer of ∼2
nm on the ∼22 nm core of hexagonal NaYbF<sub>4</sub>:Gd<sup>3+</sup> 30%/Tm<sup>3+</sup> 0.5% nanoparticles resulted in a dramatic
350 fold NIR upconversion efficiency enhancement, because of effective
suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR
upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene
glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered
saline
Evolution of Spinel LiMn<sub>2</sub>O<sub>4</sub> Single Crystal Morphology Induced by the Li<sub>2</sub>MnO<sub>3</sub> Phase during Sintering
The most severe problems for adoption of LiMn2O4 (LMO) as a low-cost and sustainable cathode in lithium-ion
batteries are manganese dissolution and structural degradation, especially
at an elevated temperature. Developing large single crystals (SCs)
for LMO could be a feasible solution since it significantly reduces
electrode/electrolyte interfaces where degradation can occur, while
exceptionally high ionic diffusivity of its spinel structure could
guarantee decent kinetics. In this work, we discovered a unique correlation
between morphology and synthesis conditions, especially oxygen partial
pressure in a successful development of defect-free faceted LMO SCs.
Further experimental and theoretical studies identified that crystal
growth of spinel LMO can be dramatically promoted by the Li2MnO3 impurity, which is spontaneously generated at low
oxygen partial pressure during high temperature synthesis. Meanwhile,
electrochemical performances were found to be controlled by both impurity
and crystallite size. We believe that with more understanding of synthesis
parameters, LMO single crystals could achieve optimal electrochemical
performance
Large Area Synthesis of a Nanoporous Two-Dimensional Polymer at the Air/Water Interface
We present the synthesis
of a two-dimensional polymer at the air/water interface and its nm-resolution
imaging. Trigonal star, amphiphilic monomers bearing three anthraceno
groups on a central triptycene core are confined at the air/water
interface. Compression followed by photopolymerization on the interface
provides the two-dimensional polymer. Analysis by scanning tunneling
microscopy suggests that the polymer is periodic with ultrahigh pore
density
Biometrical parameters of individual QTL affecting growth traits and sex of half-smooth tongue sole.
<p>R<sup>2</sup> (%): proportion of the explained phenotypic variance.</p><p>LG: linkage group.</p
Construction of a High-Density Microsatellite Genetic Linkage Map and Mapping of Sexual and Growth-Related Traits in Half-Smooth Tongue Sole (<em>Cynoglossus semilaevis</em>)
<div><p>High-density genetic linkage maps of half-smooth tongue sole were developed with 1007 microsatellite markers, two SCAR markers and an F1 family containing 94. The female map was composed of 828 markers in 21 linkage groups, covering a total of 1447.3 cM, with an average interval 1.83 cM between markers. The male map consisted of 794 markers in 21 linkage groups, spanning 1497.5 cM, with an average interval of 1.96 cM. The female and male maps had 812 and 785 unique positions, respectively. The genome length of half-smooth tongue sole was estimated to be 1527.7 cM for the females and 1582.1 cM for the males. Based on estimations of the map lengths, the female and male maps covered 94.74 and 94.65% of the genome, respectively. The consensus map was composed of 1007 microsatellite markers and two SCAR markers in 21 linkage groups, covering a total of 1624 cM with an average interval of 1.67 cM. Furthermore, 159 sex-linked SSR markers were identified. Five sex-linked microsatellite markers were confirmed in their association with sex in a large number of individuals selected from different families. These sex-linked markers were mapped on the female map LG1f with zero recombination. Two QTLs that were identified for body weight, designated as We-1 and We-2, accounted for 26.39% and 10.60% of the phenotypic variation. Two QTLs for body width, designated Wi-1 and Wi-2, were mapped in LG4f and accounted for 14.33% and 12.83% of the phenotypic variation, respectively. Seven sex-related loci were mapped in LG1f, LG14f and LG1m by CIM, accounting for 12.5–25.2% of the trait variation. The results should prove to be very useful for improving growth traits using molecular MAS.</p> </div