134 research outputs found
Internally Supported Metal–Oxide Nanocatalyst for Hydrogenation of Nitroaromatics
The
uncalcined but highly dispersive oxide-supported metal catalyst
for liquid phase reactions may suffer from the agglomeration of metal
nanoparticles and the drop of metal catalyst in solution, which will
decrease the activity and shorten their life in catalysis. Here, a
one-pot successive polyol reaction was developed to prepare M–E<i><sub>x</sub></i>O<i><sub>y</sub></i> colloidal particles
as heterogeneous nanocatalysts, which merge the controlled synthesis
of metal catalysts and oxide supports, the in situ loading of catalyst,
and even the mesopore amplification into a highly integrated process.
Unlike the traditional surface-deposited catalysts, the noble metal
nanoparticles even with a large amount of loading are internally dispersed
in the mesoporous oxide particles, which show higher activity and
stability in the hydrogenation of nitroaromatics compared to the isolated
nanocatalysts or surface-deposited catalysts. The improved activity
and stability comes from the physical confinement of metal nanoparticles
and good mass transportation of substrate/product within the support
particles. This work proposed a novel method to prepare highly dispersed
metal catalysts, which could be potentially useful to heterogeneous
catalytic reactions with high-throughput and long-life demands
Surface Cation Segregation and Chromium Deposition on the Double-Perovskite Oxide PrBaCo<sub>2</sub>O<sub>5+δ</sub>
The
surface chemistry and the Cr tolerance ability of oxygen electrodes
play a vital role in the performance and long-term stability of solid
oxide cells (SOCs). In this paper, the surface cation segregations
on the double-perovskite oxide PrBaCo<sub>2</sub>O<sub>5+δ</sub> (PBCO) and its relationship with Cr deposition are reported. During
high-temperature annealing in an O<sub>2</sub> atmosphere, the elements
Ba and Co diffuse out of the lattice and form many BaO and Co<sub>3</sub>O<sub>4</sub> precipitates on the surface, mainly located
at grain boundaries. In the presence of volatile Cr species, the observation
of BaCrO<sub>4</sub>, but not CoCr<sub>2</sub>O<sub>4</sub>, on a
segregated PBCO surface reveals that the Cr deposition preferentially
takes place on segregated BaO rather than on Co<sub>3</sub>O<sub>4</sub> precipitates. Our results show that segregated BaO precipitates
are very active toward Cr vapor and PBCO is not a Cr-tolerant oxygen
electrode for SOCs operating at high temperatures, despite its superior
electrochemical performance
Energy efficiency analysis and optimization of heat exchange network under the goal of “double carbon”: a case for production process of isopropyl acetate
In order to response to the “double carbon” strategy for reducing emissions, chemical production processes were optimized to lower the amount of utility work and equipment investment expenses with increasing the system’s capacity for heat recovery. A sensitivity analysis and the energy efficiency analysis with pinch technique were performed on the distillation and purification of the 30 kt/a isopropyl acetate (IPAC) production process by using process simulation software of Aspen Plus. The IPAC refining tower optimization results show that the purity of the refined IPAC could be reached 99.9% at circumstances of 44 theoretical plates, 19 feed plates, and 0.755 reflux ratio. According to the optimized energy consumption data from Aspen Energy Analyzer (AEA), the cold and heat logistics matching was performed. It can be seen that the heat exchange network was tuned to maximize energy recovery by reducing the amount of utility work. The optimized cold and heat utility usage were 734.69 and 727.81 kW, which meaning that compared with original process, the cold and heat utility usage energy can be save with 10.0%, respectively. The optimized results provide a certain theoretical basis and solution for improving energy saving and reducing investment costs.</p
Clinical outcomes of the levels of schwannoma at lumbar vertebrae.
<p>This table shows that the clinical outcomes of the levels of schwannoma at lumbar vertebrae.</p><p>PRE: preoperative; POST: postoperative; JOA-C: Japanese Orthopedic Association scores (JOA scores) for cervical vertebra; VAS: Visual Analogue Pain Score.</p><p>Data are expressed as the mean ± standard deviation.</p
Summary of baseline characteristics of intradural extramedullary schwannoma patients.
<p>This table showed that there was no significant difference among the three groups (Group A, Group B, Group C) in the basic characteristics (Age distribution, Gender distribution, Course of disease, and Tumor size).</p><p>CV: Cervical vertebra; TV: Thoracic vertebra; LV: Lumbar vertebra.</p><p>Data are expressed as the mean ± standard deviation.</p
Clinical outcomes of the levels of schwannoma at thoracic vertebrae.
<p>This table shows that the clinical outcomes of the levels of schwannoma at thoracic vertebrae.</p><p>PRE: preoperative; POST: postoperative; JOA-C: Japanese Orthopedic Association scores (JOA scores) for cervical vertebra; VAS: Visual Analogue Pain Score.</p><p>Data are expressed as the mean ± standard deviation.</p
Clinical outcomes of the levels of schwannoma at cervical vertebrae.
<p>This table shows that the clinical outcomes of the levels of schwannoma at cervical vertebrae.</p><p>PRE: preoperative; POST: postoperative; JOA-C: Japanese Orthopedic Association scores (JOA scores) for cervical vertebra; VAS: Visual Analogue Pain Score.</p><p>Data are expressed as the mean ± standard deviation.</p
Clinical outcomes of the levels of schwannoma at thoracic vertebrae.
<p>This table shows that the clinical outcomes of the levels of schwannoma at thoracic vertebrae.</p><p>Data are expressed as the mean ± standard deviation.</p
Table_1_The preoperative triglyceride-glucose index has a positive effect on predicting the risk of short-term restenosis after carotid artery stenting: a retrospective cohort study.pdf
BackgroundIncreasing evidence suggests that insulin resistance is linked to cardiovascular disease and atherosclerosis. The triglyceride–glucose (TyG) index has proven to be a convincing marker to quantitatively evaluate insulin resistance. However, there is no relevant information about the relationship between the TyG index and restenosis after carotid artery stenting.MethodsA total of 218 patients were enrolled. Carotid ultrasound and computed tomography angiography were used to evaluate in-stent restenosis. A Kaplan–Meier analysis and Cox regression method were performed to analyze the correlation between TyG index and restenosis. Schoenfeld residuals were used to determine the proportional-hazards assumption. A restricted cubic spline method was used to model and visualize the dose–response relationship between the TyG index and the risk of in-stent restenosis. Subgroup analysis was also performed.ResultsThirty-one participants (14.2%) developed restenosis. The preoperative TyG index had a time-varying effect on restenosis. Within 29 months post-surgery, an increasing preoperative TyG index was linked to a significant increased risk of restenosis (hazard ratio: 4.347; 95% confidence interval 1.886–10.023). However, after 29 months, the effect was decreased, although not statistically significant. The subgroup analysis showed that the hazard ratios tended to be higher in the age ≤ 71 years subgroup (p ConclusionThe preoperative TyG index was significantly associated with the risk of short-term restenosis after CAS within 29 months post-surgery. The TyG index may be employed to stratify patients based on their risk of restenosis after carotid artery stenting.</p
Polycouplings of Alkynyl Bromides and Sulfonamides toward Poly(ynesulfonamide)s with Stable C<sub>sp</sub>–N Bonds
The
development of new polymerization methodology is crucial for
polymer materials. Alkyne polymerization based on versatile reactions
of Cî—ĽC bonds have attracted much attention recently because
they can produce a great diversity of polymer materials with unsaturated
structures and potential semiconducting properties. Among that, the
polymerizations between alkyne and amine/amide which afford nitrogen-substituted
alkynes with the triple bonds strongly polarized by the nitrogen atoms
are quite attractive but challenging. In this work, the polycoupling
of alkynyl bromides and sulfonamides is reported as the first example
to generate polymers with stable N–CC bonds in the
polymer main chain. The polycoupling of various aromatic/aliphatic
alkynyl bromides and sulfonamides can be carried out at mild condition
in the presence of CuSO<sub>4</sub>·5H<sub>2</sub>O, 1,10-phenanthroline,
and K<sub>2</sub>CO<sub>3</sub> at 65 °C under nitrogen, affording
polyÂ(ynesulfonamide)Âs with high molecular weights (up to 22 000
g/mol) in high yields (up to 95%). Incorporation of luminescent tetraphenylethene
structure into the alkynyl bromide monomer can produce polymer with
aggregation-induced emission property and aggregated state fluorescence
quantum efficiency of 24.7%. The plentiful Cî—ĽC bonds of the
polymers can serve as efficient ligands for organometallization with
Co<sub>2</sub>(CO)<sub>8</sub> to generate organometallics, which
can be further pyrolyzed to afford magnetic ceramics with high magnetic
susceptibility (<i>M</i><sub>s</sub> up to 80.9 emu/g) and
low coercivity (<i>H</i><sub>c</sub> down to 0.008 kOe).
This new polycoupling reaction provides an efficient tool for the
construction of polymer materials with unique N–CC
structures, which paves the way to advanced functionalities of polymers
derived from ynesulfonamide structures
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