128 research outputs found
Access to Spirocyclic Oxindoles via N-Heterocyclic Carbene-Catalyzed Reactions of Enals and Oxindole-Derived α,β-Unsaturated Imines
A diastereoselective access to <b>β</b>-lactam fused spirocyclic oxindoles and related compounds bearing all carbon spiro centers is described. This N-heterocyclic carbene-catalyzed process employed challenging <b>β,β</b>-disubstituted <b>α,β</b>-unsaturated imines to react with enals
Copper-Catalyzed Dihydroquinolinone Synthesis from Isocyanides and <i>O</i>‑Benzoyl Hydroxylamines
A copper-catalyzed
protocol has been realized for the rapid assembly
of dihydroquinolinones from readily accessible isocyanides and O-benzoyl hydroxylamines. The reactions (10 mol % of CuOAc,
10 mol % of dppe, 3 equiv of PhONa, 30 °C) deliver various structurally
interesting dihydroquinolinones in moderate to good yields (up to
76%). The reactions may proceed in a cascade manner involving isocyanide
insertion into the N–O bond, Mumm-type rearrangement, and intramolecular
nucleophilic substitution
Copper-Catalyzed Dihydroquinolinone Synthesis from Isocyanides and <i>O</i>‑Benzoyl Hydroxylamines
A copper-catalyzed
protocol has been realized for the rapid assembly
of dihydroquinolinones from readily accessible isocyanides and O-benzoyl hydroxylamines. The reactions (10 mol % of CuOAc,
10 mol % of dppe, 3 equiv of PhONa, 30 °C) deliver various structurally
interesting dihydroquinolinones in moderate to good yields (up to
76%). The reactions may proceed in a cascade manner involving isocyanide
insertion into the N–O bond, Mumm-type rearrangement, and intramolecular
nucleophilic substitution
Electrocatalysis of formic acid on palladium and platinum surfaces : from fundamental mechanisms to fuel cell applications
Article published in: Phys. Chem. Chem. Phys., 2014, 16, 20360--20376</p
B‑Doped Pd Catalyst: Boosting Room-Temperature Hydrogen Production from Formic Acid–Formate Solutions
Facile production of hydrogen at
room temperature is an important
process in many areas including alternative energy. In this Communication,
a potent boron-doped Pd nanocatalyst (Pd-B/C) is reported for the
first time to boost hydrogen generation at room temperature from aqueous
formic acid–formate solutions at a record high rate. Real-time
ATR-IR spectroscopy is applied to shed light on the enhanced catalytic
activity of B-doping and reveals that the superior activity of Pd-B/C
correlates well with an apparently impeded CO<sub>ad</sub> accumulation
on its surfaces. This work demonstrates that developing new anti-CO
poisoning catalysts coupled with sensitive interfacial analysis is
an effective way toward rational design of cost-effective catalysts
for better hydrogen energy exploitation
Characteristics of all the participants in the survey.
Characteristics of all the participants in the survey.</p
Descriptions of self-treatment for the middle-aged and elderly in Shanxi, China
<div><p>Objectives</p><p>Self-treatment is a widespread practice among patients with common symptoms and ailments; it is necessary to explore multiple aspects of it. Notably, there is little research into self-treatment among middle-aged and elderly people, who are more likely to fall ill. Our goals are to provide a comprehensive description of self-treatment and explore associated factors with insurance utilization and expenditures among the middle-aged and elderly populations in China.</p><p>Methods</p><p>A survey was conducted in July 2016 in Shanxi, China. A stratified sampling scheme was applied to achieve representativeness. A total of 972 subjects were surveyed. Descriptive statistics, t- and Chi-squared tests, multivariate logistic regression, and multivariate linear regression were utilized.</p><p>Results</p><p>In our study, 772 (79.4%) of the surveyed subjects self-treated during the previous twelve months. Among them, 253 (32.8%) used health insurance. Subjects’ characteristics were associated with insurance utilization and expenditures for self-treatment. Total cost was positively associated with insurance utilization. The subjects with a junior high education (<i>p</i>-value < 0.001, aOR = 0.049) and senior high education (<i>p</i>-value = 0.020, aOR = 0.146) had a lower probability of using insurance. For both total costs and out-of-pocket costs, subjects who were 51 to 60 years old had lower costs. The subjects who were seriously sick and had a primary school education, as well as enterprise occupations, had higher costs. Self-treatment times were also positively associated with costs. Finally, it was found that subjects who didn’t use insurance had lower total costs.</p><p>Conclusions</p><p>The prevalence of self-treatment was high (79.4%). Some characteristics were associated with insurance utilization and expenditures in self-treatment. Our results may be helpful for policy interventions, which are needed to further improve the effectiveness of health insurance in China.</p></div
From HCOOH to CO at Pd Electrodes: A Surface-Enhanced Infrared Spectroscopy Study
The decomposition of HCOOH on Pd surfaces over a potential range of practical relevance to hydrogen production and fuel cell anode operation was probed by combining high-sensitivity in situ surface-enhanced IR spectroscopy with attenuated total reflection and thin-layer flow cell configurations. For the first time, concrete spectral evidence of COad formation has been obtained, and a new main pathway from HCOOH to COad involving the reduction of the dehydrogenation product of HCOOH (i.e., CO2) is proposed
One Step Encapsulation of Mesenchymal Stromal Cells in PEG Norbornene Microgels for Therapeutic Actions
Cell
therapies require control over the cellular response under
standardized conditions to ensure continuous delivery of therapeutic
agents. Cell encapsulation in biomaterials can be particularly effective
at providing cells with a uniformly supportive and permissive cell
microenvironment. In this study, two microfluidic droplet device designs
were used to successfully encapsulate equine mesenchymal stromal cells
(MSCs) into photopolymerized polyethylene glycol norbornene (PEGNB)
microscale (∼100–200 μm) hydrogel particles (microgels)
in a single on-chip step. To overcome the slow cross-linking kinetics
of thiol–ene reactions, long dithiol linkers were used in combination
with a polymerization chamber customized to achieve precise retention
time for microgels while maintaining cytocompatibility. Thus, homogeneous
cell-laden microgels could be continuously fabricated in a high-throughput
fashion. Varying linker length mediated both the gel formation rate
and material physical properties (stiffness, mass transport, and mesh
size) of fabricated microgels. Postencapsulation cell viability and
therapeutic indicators of MSCs were evaluated over 14 days, during
which the viability remained at least 90%. Gene expression of selected
cytokines was not adversely affected by microencapsulation compared
to monolayer MSCs. Notably, PEGNB-3.5k microgels rendered significant
elevation in FGF-2 and TGF-β on the transcription level, and
conditioned media collected from these cultures showed robust promotion
in the migration and proliferation of fibroblasts. Collectively, standardized
MSC on-chip encapsulation will lead to informed and precise translation
to clinical studies, ultimately advancing a variety of tissue engineering
and regenerative medicine practices
Insight into the Relationship between Viscosity and Hydrogen Bond of a Series of Imidazolium Ionic Liquids: A Molecular Dynamics and Density Functional Theory Study
The
viscosity of ionic liquids (ILs) is an important factor for
their industrial applications, which determines mass transfer efficiency.
In this work, the relationship between molecular structures and viscosity
for three imidazolium-based ILs is investigated by molecular dynamics
simulations and density functional theory. The shear viscosity was
calculated by using periodic perturbation method, and accurate viscosities
are obtained with less than 13% errors as compared to experimental
values. Radial distribution functions and space distribution functions
reveal that viscosities are correlated strongly to the local structures
of ion pairs. Especially, the local aggregation of anions in certain
sites of cations prevents movements of the ion pairs, which increase
the viscosities of ILs. DFT calculations were further performed to
analyze the effects of hydrogen bonds on the viscosities. The results
show that asymmetrically distributed interaction sites lead to the
high viscosities, which could be used as a rule of thumb for the future
design of ILs with target viscosity
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