171 research outputs found

    Supplemental Material, Executive_Summary_ASI-18-015_121019_v3 - Feeling Manipulated: How Tip Request Sequence Impacts Customers and Service Providers?

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    Supplemental Material, Executive_Summary_ASI-18-015_121019_v3 for Feeling Manipulated: How Tip Request Sequence Impacts Customers and Service Providers? by Nathan Warren, Sara Hanson and Hong Yuan in Journal of Service Research</p

    Supplemental Material, Please_share_with_ten_academics_ASI-18-015)_120819 - Feeling Manipulated: How Tip Request Sequence Impacts Customers and Service Providers?

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    Supplemental Material, Please_share_with_ten_academics_ASI-18-015)_120819 for Feeling Manipulated: How Tip Request Sequence Impacts Customers and Service Providers? by Nathan Warren, Sara Hanson and Hong Yuan in Journal of Service Research</p

    Synthesis of Two-Dimensional Zeolite Nanosheets Applied to the Catalytic Cracking of a Waste Cooking Oil Model Compound to Produce Light Olefins

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    Hierarchical zeolites can provide multidimensional spatial networks and, therefore, have significant potential as catalysts for the cracking of biomass to generate light olefins. The present work synthesized the diquaternary ammonium-type surfactant [C18H37–N+(CH3)2–(CH2)6–N+(CH3)2–C6H13]Br2, incorporating hydrophobic 18-carbon alkyl groups for usage as a structure-directing agent. This compound was subsequently used to prepare nanosheets of a hierarchical ZSM-5 two-dimensional zeolite (HNZSM-5) through a one-pot hydrothermal method. The crystal phase, morphology, and hierarchical structure of the HNZSM-5 were analyzed using various techniques, including X-ray diffraction, electron microscopy, and N2 adsorption/desorption. When applied to the catalytic cracking of a waste cooking oil model compound, the HNZSM-5 exhibited superior activity and stability compared with a conventional ZSM-5. This performance was attributed to the more accessible acid sites and unique lamellar structure of the former material. The HNZSM-5 also outlasted the conventional zeolite, showing deactivation after 45 h of reaction compared with 20 h, indicating exceptional stability and excellent resistance to coking

    Synthesis and Antitumor Activity of Stearate-<i>g</i>-dextran Micelles for Intracellular Doxorubicin Delivery

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    Stearate-g-dextran (Dex-SA) was synthesized via an esterification reaction between the carboxyl group of stearic acid (SA) and hydroxyl group of dextran (Dex). Dex-SA could self-assemble to form nanoscaled micelles in aqueous medium. The critical micelle concentration (CMC) depended on the molecular weight of Dex and the graft ratio of SA, which ranged from 0.01 to 0.08 mg mL−1. Using doxorubicin (DOX) as a model drug, the drug encapsulation efficiency (EE%) using Dex-SA with 10 kDa molecular weight of Dex and 6.33% graft ratio of SA could reach up to 84%. In vitro DOX release from DOX-loaded Dex-SA micelles (Dex-SA/DOX) could be prolonged to 48 h, and adjusted by a different molecular weight of Dex, the graft ratio of SA, or the drug-loading content. Tumor cellular uptake test indicated that Dex-SA micelles had excellent internalization ability, which could deliver DOX into tumor cells. In vitro cytotoxicity tests demonstrated the Dex-SA/DOX micelles could maintain the cytotoxicity of commercial doxorubicin injection against drug-sensitive tumor cells. Moreover, Dex-SA/DOX micelles presented reversal activity against DOX-resistant cells. In vivo antitumor activity results showed that Dex-SA/DOX micelles treatments effectively suppressed the tumor growth and reduced the toxicity against animal body compared with commercial doxorubicin injection

    Bimetallic Hierarchical Nanostructured Alumina Material Catalyzes Decarboxylation of Oleic Acid to Produce Long-Chain Alkanes for Bioaviation Kerosene

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    Standard alumina has only a small number of mesopores, which is not conducive to the mass transfer of biomacromolecules and so affects the catalytic activity in the case that this material is used as a catalyst substrate. In the present work, hierarchical nanostructured γ-Al2O3 (HNCγ-Al2O3) assembled from nanosheets was obtained after high-temperature calcination and a low-temperature hydrothermal treatment of an Al-MOF precursor. This material had a high Brunauer–Emmett–Teller (BET) surface area (266.8 cm3/g) and pore volume (0.64 cm3/g) together with abundant mesopores. Both monometallic and bimetallic Pt/Ni catalysts were prepared using HNCγ-Al2O3 as a carrier and applied to the decarboxylation of oleic acid to produce C8–C17 alkanes. Compared with monometallic materials, the introduction of a second metal increased the quantity and strength of acidic sites on the catalyst. A synergistic effect obtained by incorporating Pt and Ni in the bimetallic catalysts increased the number of oxygen vacancies in the materials and lowered the temperature required to reduce NiOx. At 340 °C, Pt–Ni/Al-1:3 catalyzed the decarboxylation reaction of oleic acid, giving a yield of the product C8–C17 alkanes of 85.3% after a 4 h reaction

    Catalytic Oxidation of Glycerol over Pt Supported on MOF-Derived Carbon Nanosheets

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    A series of nitrogen-doped porous carbon nanosheets (NPCNs) doped with transition-metal-supported Pt catalysts were prepared by colloidal deposition and evaluated for the selective oxidation of glycerol to glyceric acid (GLYA) under nonalkaline conditions. The transition metal contained in the catalyst was found to affect its performance and selectivity for GLYA, with the Pt/Zr@NPCN catalyst showing the highest catalytic activity and selectivity. These materials were characterized using Brunauer–Emmett–Teller surface area analysis, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and CO2 temperature-programmed desorption. The results showed that the small size of the Pt nanoparticles, the interaction between the Pt nanoparticles and the support, and the unique textural properties of the catalyst all promoted glycerol conversion and GLYA selectivity. A Zr concentration of 1.5 wt % and a support preparation temperature of 800 °C were found to provide a catalyst with the optimal performance that exhibited a glycerol conversion and selectivity for GLYA of 68.62 and 77.29%, respectively, at an initial O2 pressure of 10 bar and 60 °C after 6 h. Even after being recycled five times, this material provided a GLYA selectivity of approximately 75%, although the glycerol conversion decreased from 68 to 50%. The insights may provide new suggestions on the design of efficient support for the selective oxidation of polyols

    MOFs-Derived Mn<sub><i>x</i></sub>O<sub><i>y</i></sub>C<sub><i>z</i></sub> Supported Bimetallic Au–Pt Catalyst for the Catalytic Oxidation of Glycerol to Glyceric Acid

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    The specific structure of the support and the interactions between the catalyst components can lead to electron transfer, which in turn could affect the catalytic performance in heterogeneous catalytic reactions. In this paper, we have successfully prepared MnxOyCz composite materials from the calcination of the Mn-organic framework. Then bimetallic Au–Pt nanoparticles (NPs) were supported onto MnxOyCz via the colloidal-deposition method. These catalysts were tested in the selective oxidation of glycerol to glyceric acid under basic conditions. The results demonstrated that the catalytic activity of the bimetallic Au–Pt/MnxOyCz catalyst is considerably superior to those of the monometallic (Au and Pt) supported catalysts. Under the optimized conditions, 100% of glycerol can convert with 57.3% selectivity of glyceric acid. Multicharacterizations showed that the strong interaction between Au and Pt in the Au–Pt/MnxOyCz catalyst can enhance the dispersion of Au–Pt alloy NPs, promoting the electronic coupling effect on the metal surface. At the same time, the rich oxygen vacancies in this catalyst can facilitate the activation of oxygen, which causes the Au–Pt/MnxOyCz catalyst to show better catalytic activity. Specifically, the interaction between Au and Pt not only decreases the particle size of the Au–Pt alloy NPs but also promotes the reduction of Mn-based oxides and the mobility of oxygen. The absence of Au leads to a decrease in Pt 4f7/2 binding energy, resulting in an enrichment of electrons at the Pt active site and enhancing the oxidation ability of the primary hydroxyl group. In addition, the Au–Pt/MnxOyCz catalyst showed excellent stability without substantial loss of activity after being recycled five times. The insights and methodology may provide some new guidance for the reasonable design of bimetallic catalysts for the catalytic oxidation of biopolyols under mild conditions

    Spacer Control the Dynamic of Triplex Formation between Oligonucleotide-Modified Gold Nanoparticles

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    A novel method was developed to control the dynamic of triplex formation between oligonucleotide-modified gold nanoparticles in the presence of complementary strand. The solution containing the oligonucleotide 5′-SH-ACA CAC ACA CAC CTT TCT TTC CTT TCT TTC-3′(oligo-1)-modified gold nanoparticles was red in color. Due to triplex formation, there was a tiny change in color on addition of the complementary oligonucleotide 5′-GAA AGA AAG GAA AGA AAG-3′(oligo-3). The addition of oligonucleotide 5′-GTG TGT GTG TGT-3′(oligo-2) induced the spacer portion of oligo-1 to change from single strand to rigid duplex structure and protrude from the surface of the gold colloid, removing the physisorption between oligo-1 and the gold nanoparticles successfully. Therefore, when the oligo-2 was added accompanied by oligo-3 at pH 5.6 and 6.0 μM spermine, larger aggregates were formed and the color of the solution changed from red to blue within 20 min. The oligo-2 hybridized with the spacer portion of oligo-1 and had no effect on the stability of triplex DNA; thereby, the melting temperatures of the triplex DNA were 51 and 53 °C in the absence and presence of oligo-2, respectively. Oligo-3 played a crucial role in the triplex formation between nanoparticles. When oligo-3 was replaced with 5′-GAA AGA AAG TAA AGA AAG-3′ (oligo-4, single-base mismatched) and 5′-GAA AGT AAG GAA TGA AAG-3′ (oligo-5, double-base mismatched), respectively, the melting temperature decreased from 53 to 41 °C and eventually to 33 °C

    Targeting High Expressed α<sub>5</sub>β<sub>1</sub> Integrin in Liver Metastatic Lesions To Resist Metastasis of Colorectal Cancer by RPM Peptide-Modified Chitosan-Stearic Micelles

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    Liver metastasis is a leading death cause in colorectal cancer. The pathological differences between orthotopic tumors and metastatic lesions increased the therapeutic difficulty of metastasis. Herein, the α<sub>5</sub>β<sub>1</sub> integrin receptor expression on metastatic cells was first measured, the result showed that metastatic cells expressed the α<sub>5</sub>β<sub>1</sub> integrin higher than that of the original cells from orthotopic tumors. Afterward, RPM peptide-modified chitosan-stearic (RPM-CSOSA) was designed based on α<sub>5</sub>β<sub>1</sub> integrin expression. The cytotoxicity and resistance to migration and the invasion ability of the targeting drug delivery system loading doxorubicin (DOX) and curcumin (CUR) were evaluated in vitro. The metastatic inhibition of the targeting drug delivery system was also investigated in HT29 liver metastatic models. The modified RPM peptide could increase the cellular internalization of CSOSA micelles in metastatic tumor cells and endothelial cells mediated by α<sub>5</sub>β<sub>1</sub> integrin. The synergistic effects of RPM-CSOSA/DOX and RPM-CSOSA/CUR could obviously inhibit migratory and invasive abilities of HT29 cells and endothelial cells. Moreover, the RPM-CSOSA/DOX&RPM-CSOSA/CUR could obviously decrease the number of metastatic sites by 86.96%, while CSOSA/DOX&CSOSA/CUR decreased liver metastasis by 66.58% compared with that in the saline group. In conclusion, the RPM peptide-modified drug delivery system may provide insights into targeting the metastatic cells overexpressing the α<sub>5</sub>β<sub>1</sub> integrin, and it has the potential to inhibit liver metastasis of colorectal cancer
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