13 research outputs found

    Fe<sub>3</sub>O<sub>4</sub> Nanoparticle-Polyacrylonitrile Composite Magnetic Beads Decorated with Candida antarctica Lipase B for Long-Term Reusability in the Hydrolysis of Esters

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    The reusability of immobilized lipases, including their hydrolysis activity, is greatly affected by lipase leakage, mass transfer channel blockage, and compound deposition on the outside surface. In this study, Candida antarctica lipase B (CALB) was immobilized on Fe3O4 nanoparticle-polyacrylonitrile (PAN) composite magnetic beads through phase inversion (L/FP). The hydrolysis activity of lipase was investigated using p-nitrophenyl palmitate (p-npp) as a model ester. To overcome the limitations of immobilized lipase in ester hydrolysis, three modification strategies were employed. First, lipase was covalently immobilized on Fe3O4 nanoparticles modified with methallyl (M9) and chloro (M13) silane modifiers, which exhibited faster immobilization with reduced lipase leaching and higher activity expression and stability. Second, poly(ethylene glycol) (PEG6000) and polylactic acid (PLA) were added to the precursors to physically modify the composite structures of L/FP, resulting in modified beads with larger specific surface area (15.26 m2·g–1) and smaller average pore size (19 nm). The modified beads, L/FP-9-M and L/FP-13-M, demonstrated superior reusability in long-term hydrolysis activity over 250 cycles. L/FP-9-M retained 63 and 34% of the initial activity at the 100th cycle and the 250th cycle, respectively. L/FP-13-M retained 55 and 36% of the initial activity at the 100th cycle and the 250th cycle, respectively. Furthermore, even after 250 repeated uses, the unit activities (U·gsupport–1) of both L/FP-9-M and L/FP-13-M remained higher than the initial activity of Novo 435

    Comparison between different baseline correction methods.

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    <p>Good (a) and bad (b) trial samples after preprocessing of fNIRS data. Solid cyan curves: the time window for RDSs viewing and black screen (28s for each trial). Black curves: subjective assessments and shut-eye rests (13.3s). The averaged response of good (c) and bad (e) trial samples using traditional time-course analysis (zero order baseline corrections). The averaged response of good (d) and bad (f) trial samples using curvilinear fitting baseline corrections.</p

    Haemodynamic changes in both ROIs.

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    <p>Haemodynamic changes in the left ROI (blue bar) and right ROI (orange bar) for RDSs with 8 disparities for all participants (n = 11). Error bars represent the standard error of the mean across all participants. Statistical analysis indicates that there is a left lateralization of the activation pattern; furthermore, haemodynamic response to an RDS with 0.5° disparity is significantly stronger than to an RDS with 1.1°.</p

    Haemodynamic response and beta values.

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    <p>(a): Comparison of HbO and Hb response to stereopsis. Averaged HbO signals (red solid curve) show larger magnitude and thus better sensitivity. (b): The topography of averaged beta values for 8 disparities from all participants (n = 11). The topography shows that the occipital cortex is spatially correlated with stereoscopic vision and that the activation pattern is associated with eye dominance.</p

    Illustration of the data processing.

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    <p>(a): a bad trial sample with large background noise; (b): extracted brain activity from the raw data; (c): fitting the data by two normal distribution functions.</p

    Statistical results of subjective assessments.

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    <p>Correlations between subjective assessments and different binocular disparities (a, b, c, d). The evaluation of sustainability is correlated with the perception of stereopsis (e) and the degree of discomfort (f). Subsequent post-hoc pairwise comparisons (with FDR controlled) reveal that the differences of evaluations are all significant or marginally significant (P<sub>max</sub> = 0.052) among different disparities in (a), (b) and (d). The evaluation of RDS with 0.7° disparity is significantly larger than RDS with 1.1° in (c). *: Significance at the 0.05 level. **: Significance at the 0.01 level.</p

    The correlation between subjective assessments and fNIRS data at group level (n = 11).

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    <p>The correlation between subjective assessments and fNIRS data at group level (n = 11).</p
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