52 research outputs found
Palladium-Catalyzed Intramolecular Aminoacetoxylation of Unactivated Alkenes with Hydrogen Peroxide as Oxidant
A palladium-catalyzed intramolecular
aminoacetoxylation of unactivated
alkenes was developed in which H<sub>2</sub>O<sub>2</sub> was used
as the sole oxidant. A variety of 3-acetoxylated piperidines were
obtained in good yields with good to excellent regio- and diastereoselectivities.
Mechanistic study revealed that the addition of diÂ(2-pyridyl) ketone
(dpk) ligand was crucial to promote the oxidative cleavage of the
C–PdÂ(II) bond by H<sub>2</sub>O<sub>2</sub> to give the C–OAc
bond
Pd-Catalyzed Intramolecular Aminohydroxylation of Alkenes with Hydrogen Peroxide as Oxidant and Water as Nucleophile
A palladium-catalyzed intramolecular
aminohydroxylation of alkenes
was developed, in which H<sub>2</sub>O<sub>2</sub> was applied as
the sole oxidant. A variety of related alkyl alcohols could be successfully
obtained with good yields and excellent diastereoselectivities, which
directly derived from oxidation cleavage of alkyl C-Pd bond by H<sub>2</sub>O<sub>2</sub>. Facile transformation of these products provided
a powerful tool toward the synthesis of 2-amino-1,3-diols and 3-ol
amino acids. Preliminary mechanistic studies revealed that major nucleophilic
attack of water (S<sub>N</sub>2 type) at high-valent Pd center contributes
to the final C-OÂ(H) bond formation
Improved Interfacial Affinity and CO<sub>2</sub> Separation Performance of Asymmetric Mixed Matrix Membranes by Incorporating Postmodified MIL-53(Al)
Asymmetric mixed matrix membranesÂ(MMMs)
with MOFs hold great application potential for energy-efficient gas
separations. However, the particle aggregation and nonselective interfacial
microvoids restrict the gas separation performance of asymmetric MMMs.
Herein, nanoporous metal–organic framework (MOF) of MIL-53Â(Al)
was modified with aminosilane after solvothermal synthesis. The postfunctionalization
by grafting alkyl chains can form hydrogen bonds with polymer chains
to enhance the affinity with polymer matrix and facilitate the preferential
adsorption of CO<sub>2</sub> by dipole–quadrupole interaction
with the functional group. Then the postmodified MIL-53Â(Al) was incorporated
as filler into polyÂ(ether imide) Ultem1000 to fabricate high-quality
asymmetric MMMs with well dispersed particles in polymer matrix and
good adhesion at the MOFs-polymer interface. The Ultem/S-MIL-53Â(Al)
asymmetric MMMs exhibited remarkable combinations of gas permeance
and ideal selectivity for CO<sub>2</sub>/N<sub>2</sub> separation
at 10 wt % filler loading. The CO<sub>2</sub> permeance achieved 24.1
GPU, an increase of 165% compared with pure Ultem membrane. Meanwhile,
the ideal CO<sub>2</sub>/N<sub>2</sub> selectivity also increased
from 31.0 up to 41.1. The strategy of post covalent modification for
MOFs provides an effective way to improve the interfacial affinity
and gas separation performance
Facile Preparation and Characterization of Modified Polyurethane Sponge for Oil Absorption
Oil spills have devastating effects
on the environment. Utilization
of absorbents for oil spill cleanup has been practiced; however, the
development of cheap, reliable, environmentally friendly absorbents
is both desirable and urgent. In this study, we illustrate a novel
oil absorbent
fabricated by modifying polyurethane (PU) sponges with TiO<sub>2</sub> sol. The attachment of TiO<sub>2</sub> nanoparticles reduced the
hydrophilicity of the modified PU sponge significantly by increasing
its surface roughness and changing the chemical composition of the
surface. The modified PU sponges exhibited oil absorption capacity
of 95–110 g/g with negligible water uptake under both static
and dynamic conditions. The modified PU sponge was found to be reusable
up to 12 cycles holding 70% of its initial uptake capacity. The modified
PU sponges can be effectively used in oil spill cleanup
Facile Preparation and Characterization of Modified Polyurethane Sponge for Oil Absorption
Oil spills have devastating effects
on the environment. Utilization
of absorbents for oil spill cleanup has been practiced; however, the
development of cheap, reliable, environmentally friendly absorbents
is both desirable and urgent. In this study, we illustrate a novel
oil absorbent
fabricated by modifying polyurethane (PU) sponges with TiO<sub>2</sub> sol. The attachment of TiO<sub>2</sub> nanoparticles reduced the
hydrophilicity of the modified PU sponge significantly by increasing
its surface roughness and changing the chemical composition of the
surface. The modified PU sponges exhibited oil absorption capacity
of 95–110 g/g with negligible water uptake under both static
and dynamic conditions. The modified PU sponge was found to be reusable
up to 12 cycles holding 70% of its initial uptake capacity. The modified
PU sponges can be effectively used in oil spill cleanup
Facile Preparation and Characterization of Modified Polyurethane Sponge for Oil Absorption
Oil spills have devastating effects
on the environment. Utilization
of absorbents for oil spill cleanup has been practiced; however, the
development of cheap, reliable, environmentally friendly absorbents
is both desirable and urgent. In this study, we illustrate a novel
oil absorbent
fabricated by modifying polyurethane (PU) sponges with TiO<sub>2</sub> sol. The attachment of TiO<sub>2</sub> nanoparticles reduced the
hydrophilicity of the modified PU sponge significantly by increasing
its surface roughness and changing the chemical composition of the
surface. The modified PU sponges exhibited oil absorption capacity
of 95–110 g/g with negligible water uptake under both static
and dynamic conditions. The modified PU sponge was found to be reusable
up to 12 cycles holding 70% of its initial uptake capacity. The modified
PU sponges can be effectively used in oil spill cleanup
Multilayer Three-Dimensional Structure Made of Modified Stainless Steel Mesh for in Situ Continuous Separation of Spilled Oil
A multilayer
three-dimensional (3D) structure made of hydrophobic
stainless steel mesh has been designed for in situ continuous oil/water
separation. The hydrophobic stainless steel mesh was prepared via
a facile and environmental friendly method by etching with FeCl<sub>3</sub> solution and coating with <i>n</i>-octadecylthiol.
The as-prepared mesh allows oils
(gasoline, diesel oil, engine oil) and organic solvents (hexane, liquid
paraffin) to pass through and repels water. A separation device equipped
with the multilayer 3D structure can continuously separate the aforementioned
oils from oil–water mixtures. The separation efficiency of
continuous separation is more than 99.0 wt % and shows little decrease
after 10 cycles
Sacrificial Template Synthesis and Photothermal Conversion Enhancements of Hierarchical and Hollow CuInS<sub>2</sub> Microspheres
Hierarchical
and hollow CuInS<sub>2</sub> microspheres are synthesized on the basis
of sacrificial templates with solid and hollow CuS microspheres as
sacrificial templates, respectively. Transformations from CuS solid
microspheres to CuInS<sub>2</sub> hierarchical microspheres and CuS
hollow microspheres to CuInS<sub>2</sub> hollow microspheres can be
achieved by a solvothermal process at 180 °C for 24 h with <i>N</i>,<i>N</i>-dimethylformamide as both solvent and
reductant. The products are well characterized, and the formation
mechanisms are proposed. The as-synthesized products have strong optical
absorption from 1000 to 2000 nm in addition to normal absorption from
400 to 800 nm, which has not be reported in the literature. The as-synthesized
products exhibit a significant photothermal conversion effect under
an irradiation of a 1064 nm laser. At a laser power of 0.05 W·cm<sup>–2</sup>, up to 30% and 20% enhancement of photothermal conversion
is observed in the aqueous suspension containing 0.1 wt % CuInS<sub>2</sub> hollow microspheres and hierarchical microspheres, respectively.
The mechanisms for the enhancements of photothermal conversion in
the as-synthesized products are also discussed
Additional file 1 of The efficacy and safety of tislelizumab combined with gemcitabine plus cisplatin in the treatment of postoperative patients with muscle-invasive upper tract urothelial carcinoma
Supplementary Material 1: STROBE Statement—checklist of items that should be included in reports of observational studie
Alternative Immunomodulatory Strategies for Xenotransplantation: CD80/CD86-CTLA4 Pathway-Modified Immature Dendritic Cells Promote Xenograft Survival
<div><p>Background</p><p>Xenotransplantation is a promising approach to circumventing the current organ shortage. However, T-cell-dependent anti-xenoresponses are a major challenge to successful xenografts. Given the advantages of the use of CTLA4-Ig in the survival of allografts, the purpose of the study was to investigate the therapeutic potential of CTLA4-IgG4 modified immature dendritic cells (imDCs) in the prevention of islets xenograft rejection.</p><p>Methods</p><p>CTLA4-IgG4 was constructed by the fusion of the extracellular regions of porcine CTLA4 to human the hIgG4 Fc region. The imDCs were induced and cultured from porcine peripheral blood mononuclear cells (PBMC). The CTLA4-IgG4 modified imDCs were delivered via the portal vein to the liver of diabetic mice (insulin-dependent diabetes mellitus) before islet xenografting, and mCTLA4-Ig was administered intravenously after xenotransplantation.</p><p>Results</p><p>The xenograft survival of mice receiving unmodified imDCs was approximately 30 days. However, following administration of CTLA4-IgG4 modified imDCs before grafting and mCTLA4-Ig after grafting, xenografts survived for more than 100 days. Flow cytometric analysis showed that the CD4<sup>+</sup>CD25<sup>+</sup>Foxp3<sup>+</sup> Treg population was increased in spleens. The efficacy of donor CTLA4-IgG4 modified imDCs correlated partially with the amplification of Tregs.</p><p>Conclusions</p><p>These results confirm that selective inhibition of the direct and indirect pathways of T-cell activation by donor CTLA4-IgG4 modified imDCs and receptor CTLA4-Ig is a highly effective strategy to promote survival of xenografts.</p></div
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