123 research outputs found
A Novel Graphdiyne-Based Catalyst for Effective Hydrogenation Reaction
The
platinum nanoparticles (Pt NPs) hybrided with nanostructured carbon
materials with high stability are important for catalyzing hydrogenation
reaction. Here we reported the fabrication of ultrastable Pt NPs anchored
on graphdiyne, in which the strong interactions induced by the porous
graphdiyne can prevent the thermal migration of Pt nanoparticles on
the graphdiyne surface, exploiting the strong charge transfer interactions
from Pt NPs to GDY substrate to tune the electron density of Pt NPs.
Pt NPs catalyst with size of 2–3 nm showed high performance
on hydrogenation of aldehydes and ketones to the corresponding alcohols
compared with commercial Pt–C. Our results indicated that graphdiyne
is a promising substrate for constructing metal nanoparticle-based
heterogeneous catalysts, especially for those requiring strong interactions
between metal nanoparticles and reactants
Self-Assembly of Wheel-Shaped Nanographdiynes and Self-Template Growth of Graphdiyne
Graphdiyne
(GDY) multilayers show stacking-style-dependent physical
properties; thus, controlling the stacking style of nanostructures
is crucial for utilizing their electrical, optical, and transport
properties in electro-optical devices. Herein, we report the assemblies
of nanographdiynes decorated with substituents with different steric
hindrances to adjust the stacking style. We show that the π-stacked
aggregates were influenced by peripheral substituents and the substrate.
Steric hexaterphenyl-substituted nanoGDY scaffolds led to dimer structures
stacked in the AB-3 configuration with a twist angle of 26.01°
or the AB-1 configuration with an in-plane shift along one diyne link.
With the interval replacement of steric substituents with long C12
alkyl chains, nanoGDYs were stacked in the AB-2 configuration to decrease
the steric congestion, eventually leading to one-dimensional (1D)
nanofibrous aggregates. Self-assembly in the presence of substrates
can result in ABC-stacked nanoGDYs, which endowed us with the possibility
of using nanoGDY as the template for GDY growth in a homogeneous reaction.
High-resolution transmission electron microscopy (HRTEM), powder X-ray
diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Raman
spectroscopy, and near-infrared–ultraviolet–visible
(NIR–UV–vis) absorption spectroscopy indicate that the
crystalline GDY prepared in this way is a 1.18 eV bandgap semiconductor
Intramolecular Triplet Energy Transfer in Anthracene-Based Platinum Acetylide Oligomers
Platinum acetylide oligomers that
contain an anthracene moiety
have been synthesized and subjected to photophysical characterization.
Spectroscopic measurement and DFT calculations reveal that both the
singlet and triplet energy levels of the anthracene segment are lower
than those of the platinum acetylide segment. Thus, the platinum acetylide
segment acts as a sensitizer to populate the triplet state of the
anthrancene segment via intramolecular triplet–triplet energy
transfer. The objective of this work is to understand the mechanisms
of energy-transfer dynamics in these systems. Fluorescence quenching
and the dominant triplet absorption that arises from the anthracene
segment in the transient absorption spectrum of <b>Pt4An</b> give clear evidence that energy transfer adopts an indirect mechanism,
which begins with singlet–triplet energy transfer from the
anthracene segment to the platinum acetylide segment followed by triplet–triplet
energy transfer to the anthracene segment
Additional file 1: of Genotype × site × silviculture interactions in radiata pine: knowledge, working hypotheses and pointers for research§
Three tables listing known or postulated first-order interactions involving genotype, site and silviculture in radiata pine. These show provisional information, and as such are offered as the framework for updating, through further collation of existing literature, fresh data analysis, and fresh experimental work. Table S1. Known or postulated genotype × site interactions in radiata pine, in terms of role and effects of site on expression of genotypic differences for specific tree variables (Carson 1989; Kumar and Burdon 2010).  Table S2. Known or postulated genotype × silviculture interactions in radiata pine, in terms of role and effects of silviculture on expression of genotypic differences for specific tree variables.  Table S3. Known or postulated silviculture × site interaction in radiata pine, in terms of how impacts of site factors on means and expression of differences for specific tree variables are affected by silviculture (lower stockings/heavier thinning regimes, or fertiliser use). (DOCX 33 kb
phenotypes
This is phenotype data used in this study
Self-Assembly of Amphiphilic Homopolymers Bearing Ferrocene and Carboxyl Functionalities: Effect of Polymer Concentration, β‑Cyclodextrin, and Length of Alkyl Linker
Three new acrylamide monomers containing
ferrocene and <i>tert</i>-butyl ester groups were first
synthesized via multistep
nucleophilic substitution reaction under mild conditions followed
by reversible addition–fragmentation chain transfer (RAFT)
homopolymerization to give well-defined homopolymers with narrow molecular
weight distributions (<i>M</i><sub>w</sub>/<i>M</i><sub>n</sub> ≤ 1.36). The target amphiphilic homopolymers
were obtained by the acidic hydrolysis of <i>tert</i>-butyoxycarbonyls
to carboxyls in every repeating unit using CF<sub>3</sub>COOH. The
self-assembly behaviors of these amphiphilic homopolymers bearing
both ferrocene and carboxyl moieties in each repeating unit in aqueous
media were investigated by transmission emission microscopy (TEM),
dynamic light scattering (DLS), and atomic force microscopy (AFM).
Large compound micelles with different morphologies were formed by
these amphiphilic homopolymers, which consist of the corona formed
by hydrophilic carboxyls and the core containing numerous reverse
micelles with hydrophilic islands
of carboxyls in continuous hydrophobic phase of ferrocene-based segments.
The morphologies of the formed micelles could be tuned by the concentration
of amphiphilic homopolymers, pH value of the solution, the length
of −CH<sub>2</sub> linker between ferrocene group and carboxyl,
and the amount of β-cyclodextrin (β-CD)
Soluble Perfluorocyclobutyl Aryl Ether-Based Polyimide for High-Performance Dielectric Material
High durability of
low-<i>k</i> value is a desired property
for dielectrics serving under humid conditions, because absorbing
a small amount of moisture by the material can considerably increase
the <i>k</i> value so as to result in function deterioration.
Aiming to develop a dielectric polymer with superior durability of
low-<i>k</i> value and high thermal stability, a perfluorocyclobutyl
(PFCB) biphenyl ether-based polyimide, PFCBBPPI, was synthesized.
This polymer possesses a <i>T</i><sub>g</sub> of 310.3 °C
and a 5% weight loss temperature of 510.5 °C. PFCBBBPPI exhibited
an extremely low water uptake of 0.065 ± 0.018%, representing
the best water resistance in polyimides. The increasing percentage
in <i>k</i> value was below 2% for PFCBBPPI film exposed
to moisture under various humidity conditions for 6 h. PFCBBPPI film
equilibrated at 75% R.H. for 2 weeks still kept its <i>k</i> value below 2.50, remarkably outperforming the Kapton film. The
remarkable water resistance and resulting high durability of low-<i>k</i> property displayed by PFCBBPPI are originated from the
hydrophobic nature and small free volume fraction of the polymer,
as confirmed by contact angle test and positron annihilation lifetime
spectroscopy results. The outstanding moisture resistance and overall
performance of PFCBBPPI make it a suitable candidate for dielectric
applications under both dry and humid conditions
Targeted genetic gains for diameter-at-breast-height (DBH), wood density (DEN), predicted modulus of elasticity (PME), internal checking (IC), external resin bleeding (ERB), number of heartwood rings (NHR) in four desired-gain selection indices: A-D.
<p>Targeted genetic gains for diameter-at-breast-height (DBH), wood density (DEN), predicted modulus of elasticity (PME), internal checking (IC), external resin bleeding (ERB), number of heartwood rings (NHR) in four desired-gain selection indices: A-D.</p
Summary statistics of phenotypes assessed: Diameter-at-breast-height (DBH), wood density (DEN), predicted modulus of elasticity (PME), internal checking (IC), external resin bleeding (ERB), number of heartwood rings (NHR).
<p>Summary statistics of phenotypes assessed: Diameter-at-breast-height (DBH), wood density (DEN), predicted modulus of elasticity (PME), internal checking (IC), external resin bleeding (ERB), number of heartwood rings (NHR).</p
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