52 research outputs found

    Biosynthesis of <sup>15</sup>N<sub>3</sub>-Labeled Enniatins and Beauvericin and Their Application to Stable Isotope Dilution Assays

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    The first stable isotope dilution assay for the determination of enniatins A, A1, B, and B1 and beauvericin was developed. The <sup>15</sup>N<sub>3</sub>-labeled enniatins and beauvericin were biosynthesized by feeding two Fusarium strains Na<sup>15</sup>NO<sub>3</sub> and subsequently isolated from the fungal culture. The chemical structures of the biosynthesized products were characterized by LC-MS/MS and <sup>1</sup>H NMR. Standard solutions of <sup>15</sup>N<sub>3</sub>-labeled beauvericin, enniatin A, and enniatin A1 were accurately quantitated by quantitative NMR. On the basis of the use of the labeled products as internal standards, stable isotope dilution assays were developed and applied to various food samples using LC-MS/MS. The sample extracts were directly injected without any tedious cleanup procedures. The limits of detection were 3.9, 2.6, 3.7, 1.9, and 4.4 μg/kg for enniatins A, A1, B, and B1 and beauvericin, respectively. Limits of quantitation were 11.5 (enniatin A), 7.6 (enniatin A1), 10.9 (enniatin B), 5.8 (enniatin B1), and 13.1 μg/kg (beauvericin). Recoveries were within the range between 90 and 120%, and good intraday and interday precisions with coefficients of variation between 1.35 and 8.61% were obtained. Thus, the stable isotope dilution assay presented here is similarly sensitive and precise but more accurate than assays reported before. Analyses of cereals and cereal products revealed frequent contaminations of barley, wheat, rye, and oats with enniatins B and B1, whereas beauvericin was not quantifiable

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

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    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

    No full text
    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

    No full text
    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

    No full text
    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Effect of Cobalt Doping Concentration on the Crystalline Structure and Magnetic Properties of Monodisperse Co<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>O<sub>4</sub> Nanoparticles within Nonpolar and Aqueous Solvents

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    In this work, we investigate the effect of cobalt substitution on the size evolution, crystal structure, and magnetic properties of Fe<sub>3</sub>O<sub>4</sub> nanoparticles. Monodisperse Co<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>O<sub>4</sub> nanoparticles were prepared, using a one-step method, by direct heating process of iron­(III) and cobalt­(II) acetylacetonates in high-boiling-point inert organic solvent. The quantities of precursors added were based on stoichiometric Fe/Co ratio of desired ferrite. Elemental analyses ICP-AES evidenced successful cobalt doping. The doped particles showed a cobalt-deficient composition. Transmission electron microscopy demonstrated the large changes of particle size as a function of cobalt doping. The magnetization measurements showed an unchanged saturation magnetization only up to <i>x</i> = 0.24, beyond which it significantly decreased. To make the as-synthesized nanoparticles suitable for biomedical applications, oleic acid ligands are exchanged with caffeic acid molecules leading to stable nanoparticles in physiological conditions

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

    No full text
    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process

    No full text
    Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators. Spatial surface wetting of the film leads to the release of residual stress generated in film formation in a gradient manner, which drives the wetted regions to bidirectionally bend. By controlling the position and bending amplitude of the wetted regions, designated 3D shapes can be obtained. Moreover, Fe3+ ions in the aqueous solution used for surface wetting can coordinate with carboxylate groups in sodium alginate chains to form a gradient cross-linking network. This gradient network can not only stabilize the resulting 3D shape but also render the film with moisture-responsive morphing behaviors. Fe3+ ions can also self-assemble with tannic acid molecules to form photothermal aggregates, making the film responsive to NIR light. We further show that films with versatile 3D shapes and different modes of deformation can be fabricated by a one-step treatment process. This strategy is convenient and extendable to develop 3D-shaped polymer actuators with flexible shape-changing behaviors

    Novel Waterborne UV-Curable Hyperbranched Polyurethane Acrylate/Silica with Good Printability and Rheological Properties Applicable to Flexographic Ink

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    Novel waterborne UV-curable hyperbranched polyurethane acrylate/silica (HBWPUA/SiO<sub>2</sub>) nanocomposites were prepared by a three-step procedure and sol–gel method. <sup>1</sup>H NMR and <sup>13</sup>C NMR results indicate that HBWPU is successfully synthesized. Surface tension and contact angle tests both demonstrate the good wettability of the nanocomposites. Besides, the kinetics of photopolymerization of HBWPUA/SiO<sub>2</sub> films were analyzed by attenuated total reflection-Fourier transform infrared spectroscopy, which reveals that the modified SiO<sub>2</sub> could accelerate the curing speed of HBWPUA coatings. Thermal gravity analysis indicates that the HBWPUA/SiO<sub>2</sub> hybrid films have a better thermal stability than the pure HBWPUA cured films. Furthermore, the hybrid films show enhanced pencil hardness, abrasion resistance, and adhesion. On the basis of the above, HBWPUA/SiO<sub>2</sub> nanocomposites were finally applied to waterborne UV-curing flexographic printing ink, which is printed on poly­(ethylene terephthalate) and glass. The nanocomposite presents good rheological behavior because the ink has a lower <i>Z</i><sub>0</sub>, a higher <i>Z</i><sub>∞</sub>, and the viscosity rebuild time is 375 s. Three colors (red, yellow, and blue) of ink were used to test its printing quality, the curing time was below 30 s, and the adhesion was excellent without being stripped. All of the inks show good water resistance and abrasion resistance. Moreover, the red and blue inks possess better solid densities than the value of 1.07 of yellow ink, and are 1.83 and 1.84, respectively. The current study suggests that the process has promise in applications of food packages
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