14 research outputs found

    Tuning the Interfacial Activity of Mesoporous Silicas for Biphasic Interface Catalysis Reactions

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    Interface-active particle materials that are able to assemble at the oil/water interface so as to stabilize droplets, are gaining unprecedented interest due to the intriguing applications in catalysis and materials synthesis, etc. In contrast to these potential applications, this kind of materials are still limited and cannot meet some particular demands of practical utilizations such as rationally designed interfacial activity and high stability against concentrated salts. In this contribution, interface-active mesoporous silica nanospheres (MSS@C<sub><i>x</i></sub>Z<sub><i>y</i></sub>) are synthesized through simultaneous incorporation of extremely hydrophilic zwitterionic moiety and hydrophobic octyl moiety in the shell. The textural properties of these materials are characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and nitrogen sorption. The successful decoration of these functionalities in the shell is confirmed by Fourier transform infrared spectra (FT–IR), <sup>13</sup>C nuclear cross-polar magnetic resonance (<sup>13</sup>C CP/MAS NMR), and <sup>29</sup>Si nuclear cross-polar magnetic resonance (<sup>29</sup>Si CP/MAS NMR). The prepared mesoporous silicas exhibit tunable interfacial activity, so that oil-in-water (O/W) and water-in-oil (W/O) Pickering emulsions can be easily obtained by varying the molar fraction of these two functionalities. The MSS@C<sub><i>x</i></sub>Z<sub><i>y</i></sub>-stabilized Pickering emulsions exhibit high stability to coalescence even at 6.0 M NaCl and have relatively low surface coverage of droplets due to electrostatic repulsion, which is normally difficult to obtain for conventional particles. Interestingly, such interface-active mesoporous silicas can also carry polyoxometalate that is hosted in the nanopore to assemble at the oil/water interface and thus efficiently promotes biphasic epoxidation reactions without any external stirring, exemplifying an innovative application of theses developed mesoporous silicas

    L'Écho : grand quotidien d'information du Centre Ouest

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    04 décembre 19311931/12/04 (A60).Appartient à l’ensemble documentaire : PoitouCh

    Synthesis of Well-Defined PVDF-Based Amphiphilic Block Copolymer via Iodine Transfer Polymerization for Antifouling Membrane Application

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    An innovative strategy is devised to obtain poly­(vinylidene fluoride) membranes with splendid fouling resistance using amphiphilic block copolymer containing poly­(vinylidene fluoride) (PVDF) segments as modification agent. The PVDF-based block copolymer with poly­[2-(<i>N</i>,<i>N</i>-dimethylamino) ethyl methacrylate] as the hydrophilic segment (PVDF-<i>b</i>-PDMAEMA) was successfully fabricated by iodine transfer polymerization. This strategy not only improved the PVDF membrane structure and hydrophilicity but also assisted in fouling resistance properties as an ultrafiltration membrane. The obtained PVDF/PVDF-<i>b</i>-PDMAEMA blend membrane displayed excellent water flux, which was enhanced 3 fold compared with that of the original membrane. The bovine serum albumin (BSA) rejection ratio (≥90%) was maintained at a reasonable level. Meanwhile, by incorporation of the amphiphilic block copolymer, the PVDF-based modified membrane possessed excellent protein resistance and high flux recovery ability. The blend membranes with high BSA separation efficiency and excellent antifouling properties will find promising applications in the field of separation science specifically in sewage purification

    Hydroxyapatite Crystal Formation in the Presence of Polysaccharide

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    Natural polysaccharides play an important role in the formation of nanohydroxyapatite (nHA) crystals in biological systems. In this study, we synthesized nHA crystals in the presence of four polysaccharides, i.e., pectin, carrageenan, chitosan, and amylose, referred as PeHA, CaHA, CsHA, and AmHA, respectively. X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscope, and thermogravimetric analysis were used to investigate the formation of nHA crystals. The shape of prepared nHA crystals is needle/rod-like in all cases, whereas the size increases in the order of PeHA, CaHA, CsHA, and AmHA. The presence of polysaccharides induces the heterogeneous nucleation of nHA and further modulates the crystal growth. Our data suggest that the interaction intensity between nHA and polysaccharides is in the decreasing order of PeHA, CaHA, CsHA, and AmHA, resulting in the smallest nHA crystals with pectin. It is also demonstrated that a high polysaccharide concentration and short reaction time are adverse to nHA crystals, especially for the polysaccharides with carboxyl groups. This study can provide insight into the effects of polysaccharides with different chemical functional groups (−COOH, −OSO<sub>3</sub>H, −NH<sub>2</sub>, −OH) on the formation of nHA crystals

    Elucidating the Intercalation Pseudocapacitance Mechanism of MoS<sub>2</sub>–Carbon Monolayer Interoverlapped Superstructure: Toward High-Performance Sodium-Ion-Based Hybrid Supercapacitor

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    Two-dimensional (2D) layered materials have shown great promise for electrochemical energy storage applications. However, they are usually limited by the sluggish kinetics and poor cycling stability. Interface modification on 2D layered materials provides an effective way for increasing the active sites, improving the electronic conductivity, and enhancing the structure stability so that it can potentially solve the major issues on fabricating energy storage devices with high performance. Herein, we synthesize a novel MoS<sub>2</sub>–carbon (MoS<sub>2</sub>–C) monolayer interoverlapped superstructure via a facile interface-modification route. This interlayer overlapped structure is demonstrated to have a wide sodium-ion intercalation/deintercalation voltage range of 0.4–3.0 V and the typical pseudocapacitive characteristics in fast kinetics, high reversibility, and robust structural stability, thus displaying a large reversible capacity, a high rate capability, and an improved cyclability. A full cell of sodium-ion hybrid supercapacitor based on this MoS<sub>2</sub>–C hybrid architecture can operate up to 3.8 V and deliver a high energy density of 111.4 Wh kg<sup>–1</sup> and a high power density exceeding 12 000 W kg<sup>–1</sup>. Furthermore, a long cycle life of 10 000 cycles with over 77.3% of capacitance retention can be achieved

    A Biomimetic Poly(vinyl alcohol)–Carrageenan Composite Scaffold with Oriented Microarchitecture

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    In general, the design of a scaffold should imitate certain advantageous properties of native extracellular matrix (ECM) to operate as a temporary ECM for cells. From this perspective, a biomimetic scaffold was prepared using poly­(vinyl alcohol) and carrageenan in which axially oriented pore structure can be formed through a facile unidirectional freeze–thaw method. We examined the feasibility of this oriented scaffold, which has better physicochemical properties than a non-oriented scaffold fabricated by the conventional method. The microenvironment of this oriented scaffold could imitate biochemical and physical cues of natural cartilage ECM for guiding spatial organization and proliferation of cells in vitro, indicating its potential in cartilage repair strategy. Furthermore, the biocompatibility of the scaffold in vivo was demonstrated in a subcutaneous rat model, which revealed uniform infiltration and survival of newly formed tissue into the oriented scaffold after 4 weeks with only a minimal inflammatory response being observed over the course of the experiments. These results together indicated that the present biomimetic scaffold with oriented microarchitecture could be a promising candidate for cartilage tissue engineering

    Folic Acid Protects against Ethanol-Induced Hepatic Mitophagy Imbalance by ROS Scavenging and Attenuating the Elevated Hcy Levels

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    Ample evidence indicates that ethanol-induced oxidative stress and mitochondrial dysfunction are central to the pathogenesis of alcoholic liver disease (ALD). As an adaptive quality control mechanism, mitophagy removes dysfunctional mitochondria to avert hepatic lesions in ALD. Folic acid exhibits potential radical scavenging properties and has been proven to ameliorate mitochondrial disorder in oxidative stress-related diseases. In this study, we aimed to uncover the mitophagy regulatory effects of folic acid in a 10w alcohol C57BL/6J mice feeding model (56% v/v) and L02 cells model cultured with ethanol (2.5% v/v). The results showed that folic acid alleviates ethanol-induced liver injury, decreasing oxidative stress and restoring liver enzyme. Furthermore, folic acid improved the mitochondrial function and inhibited ethanol-activated mitophagy through decreasing PINK1–Parkin and Drp1 expression, which inhibited the release of mitochondrial cytochrome C to the cytoplasm, preventing hepatocyte apoptosis. Intriguingly, folic acid attenuates the elevated hepatic homocysteine (Hcy) level. Additionally, the pretreatment of L02 cells with folic acid also ameliorated Hcy-induced oxidative damage, mitochondrial fission, and mitophagy. In summary, these results suggest that folic acid has beneficial effects in mitophagy remodeling by ROS scavenging and facilitating Hcy metabolism and could be developed as a potential therapeutic agent against ALD
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