118 research outputs found
Revisiting Vibrational Circular Dichroism Spectra of (S)-(+)-Carvone and (1S,2R,5S)-(+)-Menthol Using SimIR/VCD Method
The VCD spectra of (<i>S</i>)-(+)-carvone and
(1<i>S</i>,2<i>R</i>,5<i>S</i>)-(+)-menthol
are recalculated using the DFT method with extended conformation and
configuration spaces. The calculated individual and averaged spectra
are compared against observed ones using the previously reported similarity
index, <i>S</i><sub>V</sub>. It is found that the <i>S</i><sub>V</sub> population forms approximately two normal
distributions, depending on whether a spectrum matches the observed
one or not. This statistical character can be used to estimate the
error in absolute configuration (AC) assessments. To avoid erroneous
AC assignments and incomplete conformation searching, it is advisible
to employ a minimum |<i>S</i><sub>V</sub>| of 0.2 and maximize
it using conformation averaging. It is demonstrated that this approach
is suitable and robust for flexible chiral molecules
Efficient Removal of Anionic Radioactive Pollutant from Water Using Ordered Urea-Functionalized Mesoporous Polymeric Nanoparticle
A urea-functionalized
ordered mesoporous polymeric nanoparticle for removing the perrhenate
anion ReO<sub>4</sub><sup>–</sup> as the surrogate of the particularly
intractable anion radioactive pollutant TcO<sub>4</sub><sup>–</sup> was demonstrated in the present study. This nanomaterial (denoted
as urea-MPN) was produced for the first time by a surfactant-directed
urea-phenol-formaldehyde resol oligomers self-assembly protocol under
hydrothermal condition. The obtained urea-MPN possessed the uniform
nanosized spherical morphology with a 3D interconnected ordered cubic
mesoporous structure. Also, the urea functional groups were succefully
embedded in the polymer framework without the alteration of the molecular
configuration. Meanwhile, it exhibited excellent β radiation
resistance up to 200 kGy dose. We employed the perrhenate anion ReO<sub>4</sub><sup>–</sup> to test its potential for the removal
of anionic radioactive pollutant TcO<sub>4</sub><sup>–</sup> from water. Interestingly, the optimized urea-MPN nanocomposite
achieved the high removal efficiency at a low concentration of 0.25
mM within a short contact time of 30 min. The control experimental
results revealed that the short nanoscale pore channels and the hydrophobic
mesopore surface facilitated the hydrogen-bonding interaction between
the charge-diffuse ReO<sub>4</sub><sup>–</sup> tetrahedral
oxoanion and the urea moieties in the framework of urea-MPN, accounting
for the rapid and effective removal performance in pure water. Importantly,
it can selectively capture ReO<sub>4</sub><sup>–</sup> in the
presence of different competitive anions including NO<sub>3</sub><sup>–</sup>, CO<sub>3</sub><sup>2–</sup>, SO<sub>4</sub><sup>2–</sup>, and PO<sub>4</sub><sup>3–</sup>. This
attractive capability of this unique nanosized mesoporous polymeric
sorbent will pave the way for the diverse applications in the decontamination
of nuclear wastes in a more economical and sustainable manner
Surface-Stress-Induced Phase Transformation of Ultrathin FeCo Nanowires
Ultrathin
metal nanowires have attracted wide attention becau se
oftheir unique anisotropy and surface-to-volume effects. In this study,
we use ultrathin Au nanowires as the templating core to epitaxially
grow magnetic iron–cobalt (FeCo) shell through metal-redox
with the control on their thickness and stoichiometry. Large surface-stress-induced
phase transformation in Au nanowires triggers and stabilizes metastable
tetragonal FeCo nanostructure to enhance its magnetic anisotropy and
coercivity. Meanwhile, under illumination, plasmon-induced hotspot
in ultrathin Au nanowires enables the light-control on magnetic characteristics
of FeCo shell. This study demonstrates the feasibility of surface-stress-induced
phase transformation to stabilize and control metastable nanostructures
for enhanced magnetic anisotropy, which is one of the key properties
of functional magnetic materials
Comparative Analysis of Antioxidant Activity and Functional Components of the Ethanol Extract of Lotus (<i>Nelumbo nucifera</i>) from Various Growing Regions
The
variations in antioxidant activity and concentration of functional
components in the ethanol extracts of lotus seeds and rhizomes based
on the growing region and dryness were investigated. Free radical
scavenging activity, total phenolic and flavonoid content, and concentration
of several specific flavonoids and alkaloids in the ethanol extracts
of lotus were measured. Antioxidant activity and its correlative total
phenolic content varied characteristically depending on the growing
region and dryness. High-perfomance liquid chromatography analysis
showed that the ethanol extracts of lotus seeds from Vietnam (Ho Chi
Minh City), raw rhizomes from Korea (Siheung), and dried rhizomes
from Japan (Nigata) had the greatest specific flavonoid content. The
ethanol extracts of seeds from China (Hubei), raw rhizomes from Japan
(Nigata), and dried rhizomes from Korea (Siheung) had the greatest
specific alkaloid content. Astragaline, rutin, isoquercetin, nuciferine,
dauricine, isoliensinine, and neferine were identified in lotus rhizomes
for the first time in this study
Metal-Redox Synthesis of MnBi Hard Magnetic Nanoparticles
High
coercivity MnBi alloy is a promising candidate as earth abundant
permanent magnet for energy-critical technologies. We report here
a new metal-redox method to synthesize colloidal MnBi nanoparticles,
exhibiting a saturation magnetization of 49 emu/g and coercivity of
15 kOe. It is shown that the magnetic properties of the MnBi nanoalloys
can be readily modified by precursor stoichiometry, temperature ramp
rate, and reaction temperature, making it a versatile scalable strategy
for generation of MnBi
Identification precision of different categories.
<p>Identification precision of different categories.</p
Bamboo-like Composites of V<sub>2</sub>O<sub>5</sub>/Polyindole and Activated Carbon Cloth as Electrodes for All-Solid-State Flexible Asymmetric Supercapacitors
A bamboo-like nanomaterial composed
of V<sub>2</sub>O<sub>5</sub>/polyindole (V<sub>2</sub>O<sub>5</sub>/PIn) decorated onto the activated carbon cloth was fabricated for
supercapacitors. The PIn could effectively enhance the electronic
conductivity and prevent the dissolution of vanadium. And the activation
of carbon cloth with functional groups is conducive to anchoring the
V<sub>2</sub>O<sub>5</sub> and improving surface area, which results
in an enhancement of electrochemical performance and leads to a high
specific capacitance of 535.5 F/g. Moreover, an asymmetric flexible
supercapacitor based on V<sub>2</sub>O<sub>5</sub>/PIn@activate carbon
cloth and reduced graphene oxide (rGO)@activate carbon cloth exhibits
a high energy density (38.7 W h/kg) at a power density of 900 W/kg
and good cyclic stability (capacitance retention of 91.1% after 5000
cycles). And the prepared device is shown to power the light-emitting
diode bulbs efficiently
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