313 research outputs found
Surprisingly High Selectivity and High Affinity in Mercury Recognition by H‑Bonded Cavity-Containing Aromatic Foldarands
In the absence of macrocyclic ring
constraints, few synthetic systems,
possessing a mostly solvent-independent well-folded conformation that
is predisposed for highly selective and high affinity recognition
of metal ions, have been demonstrated. We report here such a unique
class of conformationally robust modularly tunable folding molecules
termed foldarands that can recognize Hg<sup>2+</sup> ions surprisingly
well over 22 other metal ions. Despite the lack of sulfur atoms and
having only oxygen-donor atoms in its structure, the best foldarand
molecule, i.e., tetramer <b>4</b>, exhibits a selectivity factor
of at least 19 in differentiating the most tightly bound Hg<sup>2+</sup> ion from all other metal ions, and a binding capacity that is ≥18
times that of thio-crown ethers. These two noteworthy binding characters
make possible low level removal of Hg<sup>2+</sup> ions. With a [<b>4</b>]:[Hg<sup>2+</sup>] molar ratio of 5:1 and a single biphasic
solvent extraction, the concentration of Hg<sup>2+</sup> ions could
be reduced drastically by 98% (from 200 to 4 ppb) in pure water. <b>4</b> could also effect a highly efficient reduction in mercury
content by 98% (from 500 to 10 ppb) in artificial groundwater via
multiple successive extractions with an overall consumption of <b>4</b> being 9:1 in terms of [<b>4</b>]:[Hg<sup>2+</sup>]
molar ratio
Surprisingly High Selectivity and High Affinity in Mercury Recognition by H‑Bonded Cavity-Containing Aromatic Foldarands
In the absence of macrocyclic ring
constraints, few synthetic systems,
possessing a mostly solvent-independent well-folded conformation that
is predisposed for highly selective and high affinity recognition
of metal ions, have been demonstrated. We report here such a unique
class of conformationally robust modularly tunable folding molecules
termed foldarands that can recognize Hg<sup>2+</sup> ions surprisingly
well over 22 other metal ions. Despite the lack of sulfur atoms and
having only oxygen-donor atoms in its structure, the best foldarand
molecule, i.e., tetramer <b>4</b>, exhibits a selectivity factor
of at least 19 in differentiating the most tightly bound Hg<sup>2+</sup> ion from all other metal ions, and a binding capacity that is ≥18
times that of thio-crown ethers. These two noteworthy binding characters
make possible low level removal of Hg<sup>2+</sup> ions. With a [<b>4</b>]:[Hg<sup>2+</sup>] molar ratio of 5:1 and a single biphasic
solvent extraction, the concentration of Hg<sup>2+</sup> ions could
be reduced drastically by 98% (from 200 to 4 ppb) in pure water. <b>4</b> could also effect a highly efficient reduction in mercury
content by 98% (from 500 to 10 ppb) in artificial groundwater via
multiple successive extractions with an overall consumption of <b>4</b> being 9:1 in terms of [<b>4</b>]:[Hg<sup>2+</sup>]
molar ratio
One-Pot Synthesis of Strained Macrocyclic Pyridone Hexamers and Their High Selectivity toward Cu<sup>2+</sup> Recognition
The removal of Cu<sup>2+</sup> ions
is relevant to environmental
pollution control and neurodegenerative disease treatment. A novel
family of strained macrocyclic pyridone hexamers, which exhibit highly
selective recognition of Cu<sup>2+</sup> ions and reduce copper content
in artificial seawater by 97% at a very low [host]:[CuCl<sub>2</sub>] molar ratio of 2:1, is documented
Revealing Surface States in In-Doped SnTe Nanoplates with Low Bulk Mobility
Indium (In) doping in topological
crystalline insulator SnTe induces superconductivity, making In-doped
SnTe a candidate for a topological superconductor. SnTe nanostructures
offer well-defined nanoscale morphology and high surface-to-volume
ratios to enhance surface effects. Here, we study In-doped SnTe nanoplates,
In<sub><i>x</i></sub>Sn<sub>1–<i>x</i></sub>Te, with <i>x</i> ranging from 0 to 0.1 and show they superconduct.
More importantly, we show that In doping reduces the bulk mobility
of In<sub><i>x</i></sub>Sn<sub>1–<i>x</i></sub>Te such that the surface states are revealed in magnetotransport
despite the high bulk carrier density. This is manifested by two-dimensional
linear magnetoresistance in high magnetic fields, which is independent
of temperature up to 10 K. Aging experiments show that the linear
magnetoresistance is sensitive to ambient conditions, further confirming
its surface origin. We also show that the weak antilocalization observed
in In<sub><i>x</i></sub>Sn<sub>1–<i>x</i></sub>Te nanoplates is a bulk effect. Thus, we show that nanostructures
and reducing the bulk mobility are effective strategies to reveal
the surface states and test for topological superconductors
Intense Photocurrent from Mo-Doped TiO<sub>2</sub> Film with Depletion Layer Array
A novel
bilayer structure of TiO<sub>2</sub> film was found capable of yielding
fairly strong photocurrent under visible light. The base layer was
lightly doped with Mo and then etched by reactive ion beam, and was
finally covered by an undoped TiO<sub>2</sub> surface layer. Because
of Fermi level drop at the interface of the trenches, such a deposition–etching–redeposition
process implanted an array of depletion layer into TiO<sub>2</sub> film successfully. Microstructures, crystallite parameters, and
the absorption property were investigated with scanning electron microscope,
atomic force microscopy, X-ray diffraction, and ultraviolet–visible
spectroscopy in order. Photocurrent density was collected on an electrochemical
workstation under visible light. The results indicate that carrier
collection probability near depletion layer was enhanced significantly
owing to high parallel diffusivity. Under visible light, current density
demonstrates a marked increase as etching depth grows. At an etching
depth around 660 nm, photocurrent density achieved is 56 times larger
than TiO<sub>2</sub> film. Depletion layer at vertical trench edges
may have a much bigger universal value than anticipated for various
doping cases of wide-bandgap films
SCFAs concentration analyzed by gas chromatography (GC).
<p>a, acetate; b, butyrate; c, propionate. Data with asterisk were significantly different (<i>p</i><0.05).</p
The comparison of TNF-α during the period of experiment.
<p>Data with asterisk were significantly different (p<0.05).</p
Representative HE images that were used for mucus layer thickness measurements (n = 4).
<p>1 from the control, 2 from 20<sup>−1</sup> Cd, 3 from 100 mg kg<sup>−1</sup> Cd. IM, inner mucus layer, (A). Thickness of the mucus layer measured by histological analyses after HE staining. Data with asterisk were significantly different (<i>p</i><0.05), (B).</p
Comparison of the diameter of the colony between control and Cd treatments during the period of incubation.
<p>Comparison of the diameter of the colony between control and Cd treatments during the period of incubation.</p
The result of qPCR for butyryl CoA transferase (BCoAT) and formyltetrahydrofolate synthetase (FTHFS) genes.
<p>Values were the percentage of BCoAT copies/Bacteria copies and FTHFS copies/Bacteria copies.</p
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