As the core material to realize the polarization function, the homogeneity of poly(vinyl alcohol) (PVA) film directly affects the polarization performance, transmittance, color tone, and other key optical indicators of the polarization film. However, due to the rapid volatilization of solvents in the actual production process, the phase transition occurs in a very short time, and there is not enough time to attain the equilibrium state, which will cause a gradient structure in the thickness direction. Herein, we proposed a strategy to suppress the skin-core structure by shifting the drying process of PVA solution from evaporation-induced dominance to diffusion-induced dominance to slow down the drying rate. For this purpose, PVA aqueous solutions with five different initial concentrations (C0) from 10 wt % to 21.4 wt % were prepared, and the film formation process was monitored in situ. It was found that there existed a critical concentration; i.e., when the C0 of the PVA aqueous solution exceeded this concentration (18 wt %), the dried film was homogeneous, and when the C0 was lower than this value, the skin-core structure appeared. Moreover, by monitoring the drying process of PVA solutions with different C0s in real-time, we observed that the drying rate of PVA solutions can be effectively slowed when the double hydrogen-bonded water and multiple hydrogen-bonded water were predominant as the critical concentration exceeded 18 wt %. Thus, the homogeneous PVA film is formed by retarding the evaporation and crystallization process. This study contributes to the structural development of PVA optical films with uniform structures and provides theoretical support for the design and fabrication of polarized films.
Coprinus comatus is an edible mushroom and its fermented product possesses antioxidant activity. In this study, to further enhance the antioxidant activity and improve the reusability of the strain, calcium alginate hydrogel was used as the carrier for embedding and immobilizing Coprinus comatus. The effects of CaCl2 concentration, sodium alginate concentration, microsphere diameter, and the amount of magnetic particle on the antioxidant activity of fermented products were investigated. The results showed that the magnetic immobilized microsphere prepared by 2.50% CaCl2, 2.00% sodium alginate and 0.50% Fe3O4 had the best fermentation antioxidant activity (EC50 was 0.43 ± 0.01 mg/mL) when the diameter was 5 mm, which increased by 24.56% compared to the initial activity. Besides, the microsphere showed strong reusability, the antioxidant activity was still better than the free strain after being used five times. This study not only enhanced the antioxidant activity of Coprinus comatus fermented product through immobilization, but also provided an effective method for microbial fermentation.
Ethylenediaminetetraacetic acid (EDTA) pretreatment has been shown to overcome complement interference in the single-antigen bead (SAB) assay. However, a quantitative evaluation of its impact on the assay for preemptive application to diverse clinical samples is still lacking.Serum samples from 95 renal transplant candidates were tested with and without EDTA-pretreatment in parallel. Changes in mean fluorescence intensity (MFI) values were analyzed to determine the impact of EDTA-pretreatment and the characteristics of complement interference.MFI values from EDTA-treated and untreated sera showed good correlations (r = 0.99) and were linear after excluding outliers (slopes, 1; intercepts, -63.7 and -24.2 for class I and II, respectively). Using an assay cutoff of 2000 MFI, positive/negative assignments were concordant for 99% of the 9215 class I beads and 9025 class II beads tested. As defined by an MFI increment above 4000 after EDTA pretreatment, complement interference affected 172 class I beads in 12 samples (12.6%) and 60 class II beads in 7 samples (7.4%), and the findings were supported in 83% and 86% of these samples by dilution studies. In a case study, EDTA pretreatment prevented falsely low MFI values and facilitated the interpretation of titration curves. Finally, EDTA pretreatment reduced the coefficient of variance (CV) by 2.1% and 2.4% for class I and II beads respectively (P < 0.0001).It is safe to preemptively treat all clinical samples with EDTA before SAB assay to prevent false negative results or falsely low MFI values. EDTA pretreatment has the added benefit of improved assay precision.
Abstract Network topology is manipulated in free‐radical copolymerization via proper selection of crosslinker type and its respective properties when paired with specific monomers. Our prior work has focused on the impact of the reduced reactivity parameter Ψ applied to a pendent vinyl, characteristic for each monomer/crosslinker pair, yet here we assess the relative importance of the comonomer reactivity ratios to see whether one factor can counterbalance the other. The traditional reactivity ratio determines when the crosslinker molecule is incorporated into the polymer backbone, while the reduced reactivity Ψ parameter relates to the efficiency of the resulting pendent side chain vinyl being utilized to form a crosslink node at some later point during the polymerization. Both factors are then contrasted with simply the overall loading of crosslinker. Either n ‐butyl methacrylate ( n ‐BMA) or styrene (STY) was chosen as a primary backbone monomer to copolymerize with one of three crosslinkers: 1,4‐butanediol dimethacylate (BDDMA), 1,4‐butanediol diacrylate (BDDA), or divinylbenzene (DVB). Both kinetics and gel can be most dramatically boosted when a crosslinker is applied having a reactivity ratio favouring early insertion. This in turn leads to an earlier onset of gel formation, which ultimately results in greater final gel content. This amplification of both kinetics and gel can overcome an otherwise small Ψ due to crosslinker or main monomer choice. This reactivity ratio effect was further confirmed by Monte Carlo simulations. By whatever mechanism (higher Ψ, lower r A , or higher crosslinker level), earlier onset of gelation produces more gel overall and a tighter network topology.
A scale-up model for photoreactors based on a comparative study of the photocatalytic efficiency of suspended and immobilized systems was developed. The model is independent of reactor size and configurations, and it assumes that photocatalytic efficiency is the same when normalized per unit of illuminated catalyst area in both systems. In all cases, phenol/TiO2 (Degussa P25) was selected as the photodegradation system. First, a kinetic model was built in an immobilized system based on the corresponding experimental data, and then predicted rates of phenol degradation in the suspended system were calculated using the above kinetic model combined with a simplified radiation model, which was expressed as an apparent form of the Lambert law. Second, to obtain experimental rates, experiments conducted in the suspended system were carried out under the same conditions used in the immobilized system. Ratios between experimental rates and predicted rates were obtained, revealing the differences in efficiency between the suspended and immobilized systems. The typical value of the ratio was 2.5−9.2, suggesting that the efficiency of the suspended system was 2.5−9.2 times higher than that of the immobilized system. The ratio decreased with increasing concentrations of both phenol and catalyst. When the catalyst concentration and initial concentration of phenol were set, the ratio became constant within the range of the light intensity of 1.71−3.60 mW cm−2. Finally, for photoreactor scale-up, the proposed model was validated in a larger photoreactor operated in the suspended system, and good agreements were obtained with errors less than 5%. This methodology provides an alternative to the scale-up of photoreactors, which allows for easier engineering applications.
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