29 research outputs found

    AKTIVITAS ANTIOKSIDAN SEDIAAN NANOPARTIKEL KITOSAN EKSTRAK ETANOL KELOPAK ROSELA (Hibiscus sabdariffa L) PADA TIKUS HIPERKOLESTEROL : PENGUKURAN KADAR MALONDIALDEHID (MDA)

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    Hypercholesterolemia can induce oxidative stress and are associated with atherosclerosis and other cardiovascular disorders. Administration of a preparation of chitosan nanoparticles roselle extract (NKER) can prevent oxidative stress because it contains flavonoids which have an effect as an antioxidant anthocyanin. Decreased oxidative stress can be determined by measuring the levels of malondealdehid (MDA) produced by the reaction of lipid peroxidation. The purpose of this study was to determine the effect of administration of a preparation of chitosan nanoparticles roselle calyx ethanol extract of antioxidant activity by measuring the levels of MDA. This study used 25 adult rats of Sprague Dawley strain were divided into 5 groups. The first group was given a standard feed diet as baseline, group II was induced with pure cholesterol. Group III, IV and V induced pure cholesterol as well as the dosage given NKER with successive doses of 25 mg/kg, 50 mg/kg and 100 mg/KgBB. The treatment was done for 30 days. On day - 31 each rat blood taken for measurement of total cholesterol, as well as the measurement of MDA using thiobarbituric acid reactive substance (TBARS). The results showed an increase in levels of MDA in mice induced pure cholesterol (group II) with a mean concentration of 7.13 ± 0.22 nmol / ml significantly different to the baseline with a mean concentration of 0.87 ± 0.77 nmol / ml (p≤0,05). The mean levels of MDA in group III, IV and V respectively was 5.49 ± 0.18 nmol / ml; 4.18 ± 0.37 nmol / ml; and 2.18 ± 0.15 nmol / ml,significantly different when compared with the baseline group and the group II (p≤0,05). Decreased levels of MDA in mice given dosage NKER hypercholesterolemia showed that nker preparations have antioxidant activity, which is owned by the highest antioxidant activity NKER dosage dose 100mg/KgBB. Keywords : Antioxidant, Nanoparticles, Roselle, malondialdehyd

    Selective Catalytic Reduction of NO<sub><i>x</i></sub> with NH<sub>3</sub> over Novel Fe–Ni–Ti Catalyst

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    A novel Fe–Ni–Ti composite oxide prepared via the hydrothermal method has been developed for the selective catalytic reduction of NO<sub><i>x</i></sub> with NH<sub>3</sub>. This environmentally benign catalyst showed high activity and excellent selectivity to N<sub>2</sub>, which is superior to that of Fe–Ti and Ni–Ti catalysts. Catalyst characterization results revealed that over Fe–Ni–Ti catalyst the dual redox cycles (Fe<sup>3+</sup> + Ni<sup>2+</sup> ↔ Fe<sup>2+</sup> + Ni<sup>3+</sup>, Ti<sup>4+</sup> + Ni<sup>2+</sup> ↔ Ti<sup>3+</sup> + Ni<sup>3+</sup>) are crucial for the enhanced activity. The synergetic effect among Fe, Ni, and Ti leads to not only the increased redox property, but also improved surface acidity. DRIFT experiments demonstrated that more reactive NH<sub>3</sub>/NH<sub>4</sub><sup>+</sup> and M-NO<sub>2</sub> nitro species formed over Fe–Ni–Ti catalyst, thus resulting in the efficiently catalytic removal of NO<sub><i>x</i></sub>

    Rapid Intracellular Growth of Gold Nanostructures Assisted by Functionalized Graphene Oxide and Its Application for Surface-Enhanced Raman Spectroscopy

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    Hybridization of metal nanoparticles with graphene oxide for high performance surface-enhanced Raman scattering (SERS) has attracted overwhelming attention in recent years. Herein, a one-pot green route for intracellular synthesis of gold nanostructures assisted by poly­(vinylpyrrolidone) (PVP)-functionalized graphene oxide (GO) was proposed. The hybrids obtained [GO/PVP/intracellularly grown gold nanoparticles (IGAuNs)] randomly scattered throughout the cell. Compared with the IGAuNs, the growth of GO/PVP/IGAuNs was remarkably accelerated, which could be attributed to the coordination of PVP enriched on GO. GO/PVP/IGAuNs could serve as excellent SERS probes for ultrasensitive detection of cellular components of cancer cells located in the cytoplasm, nucleoplasm, and nucleolus. The random intracellular distribution of GO/PVP/IGAuNs facilitated the effective Raman characterization of cellular components, which was confirmed by the uniform distribution of SERS signals in the Raman image. The SERS signals induced by GO/PVP/IGAuNs could be collected as early as 15 h, which allowed rapid detection of tumor cells. In conclusion, this facile and green strategy for fast intracellular growth of GO/PVP/IGAuNs offered great potential for biomedical applications

    Structural schematic of Trx-Balcp19k.

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    <p>The Trx-Balcp19k is a hybrid protein with C-terminal Balcp19k and N-terminal Trx tag, His tag and S tag, as well as thrombin and enterokinase recognition sites.</p

    Adhesive aggregation formed by Trx-Balcp19k when dialyzed against Milli-Q water.

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    <p>(A) Sticky aggregation was generated after Trx-Balcp19k eluate was dialyzed against pure water, which was termed “Trx-Balcp19k gel” for simple description. (B) The slices of lyophilized Trx-Balcp19k gel. (C) The disaggregated Trx-Balcp19k exhibited a foam-like morphology when freeze dried, and therefore it was termed “Trx-Balcp19k foam”.</p

    Schematic illustration of the single-lap-joint shear strength test.

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    <p>Aluminum plate with a thickness of ~1 mm was cut into 100 mm × 10 mm sheets. A small hole was drilled at one end of the aluminum sheet for convenient fixation. During the test, two adhesively-bonded aluminum adherents with an overlapping area of 12 mm × 10 mm were torn apart in the directions indicated by the arrows.</p

    Biochemical composition of the Trx-Balcp19k gel.

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    <p>The SDS-PAGE analysis (A) indicated that the Trx-Balcp19k gel was actually non-covalently aggregated soluble Trx-Balcp19k based on the identical protein bands observed between Trx-Balcp19k gel and Trx-Balcp19k foam. The Trx-Balcp19k gel is proteinaceous, since only trace amounts of carbohydrates (B) and no lipids (C) were detected.</p

    Adhesion strength of Trx-Balcp19k gel measured using a single-lap-joint shear strength test.

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    <p>(A) Representative load-distance profile of Trx-Balcp19k gel. (B) Adhesive shear strengths of several protein samples. The aggregated Trx-Balcp19k (Trx-Balcp19k gel) showed a greater adhesion strength (2.10 ± 0.67 MPa) compared to PVA craft glue (1.77 ± 0.54 MPa) and UHU glue (1.78 ± 0.65 MPa), while the disaggregated Trx-Balcp19k (Trx-Balcp19k foam) had an extremely low adhesion strength (40 ± 8 kPa), which was even lower than that of BSA (70 ± 15 kPa).</p

    Selective Catalytic Reduction of NO<sub><i>x</i></sub> by NH<sub>3</sub> over Mn-Promoted V<sub>2</sub>O<sub>5</sub>/TiO<sub>2</sub> Catalyst

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    The effect of Mn on the catalytic performance of V<sub>2</sub>O<sub>5</sub>/TiO<sub>2</sub> catalyst for the selective catalytic reduction of NO<sub><i>x</i></sub> by NH<sub>3</sub> (NH<sub>3</sub>-SCR) has been investigated in this study. It was found that the added Mn significantly enhanced the activity of V<sub>2</sub>O<sub>5</sub>/TiO<sub>2</sub> catalyst for NH<sub>3</sub>-SCR below 400 °C. The redox cycle (V<sup>4+</sup> + Mn<sup>4+</sup> ↔ V<sup>5+</sup> + Mn<sup>3+</sup>) over Mn-promoted V<sub>2</sub>O<sub>5</sub>/TiO<sub>2</sub> catalyst plays a key role for the high catalytic deNO<sub><i>x</i></sub> performance. The redox cycle promotes the adsorption and activation of NH<sub>3</sub> and NO, forming more reactive intermediates (NH<sub>4</sub><sup>+</sup>, coordinated NH<sub>3</sub>, NO<sub>2</sub>, and monodentate nitrate species), thus promoting the NH<sub>3</sub>-SCR to proceed

    Novel Mn–Ce–Ti Mixed-Oxide Catalyst for the Selective Catalytic Reduction of NO<sub><i>x</i></sub> with NH<sub>3</sub>

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    Mn–Ce–Ti mixed-oxide catalyst prepared by the hydrothermal method was investigated for the selective catalytic reduction (SCR) of NO<sub><i>x</i></sub> with NH<sub>3</sub> in the presence of oxygen. It was found that the environmentally benign Mn–Ce–Ti catalyst exhibited excellent NH<sub>3</sub>-SCR activity and strong resistance against H<sub>2</sub>O and SO<sub>2</sub> with a broad operation temperature window, which is very competitive for the practical application in controlling the NO<sub><i>x</i></sub> emission from diesel engines. On the basis of the catalyst characterization, the dual redox cycles (Mn<sup>4+</sup> + Ce<sup>3+</sup> ↔ Mn<sup>3+</sup> + Ce<sup>4+</sup>, Mn<sup>4+</sup> + Ti<sup>3+</sup> ↔ Mn<sup>3+</sup> + Ti<sup>4+</sup>) and the amorphous structure play key roles for the high catalytic deNO<sub><i>x</i></sub> performance. Diffuse reflectance infrared Fourier transform spectroscopy studies showed that the synergetic effect between Mn and Ce contributes to the formation of reactive intermediate species, thus promoting the NH<sub>3</sub>-SCR to proceed
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