Plutonium-239 sorption and transport on/in unsaturated sediments: comparison of batch and column experiments for determining sorption coefficients

Sorption (distribution) coefficients of plutonium were most often derived by static batch experiments. However, it is not clear how unsaturated flow conditions including moisture content and pore water velocity change the sorption coefficients. Transport experiments of plutonium through the unsaturated sediments packed into the columns were then performed in order to determine the sorption coefficients (column-K _ds). Static batch experiments were also conducted to obtain batch-K _ds and then compare the differences between batch-K _ds and column-K _ds. The results show that unsaturated flow conditions had no significant effect on column-K _ds, and the average column-K _d value was 1.74 ± 0.02 m³/kg. By comparison, batch-K _d values spanned several orders of magnitude, regardless of the specified liquid–solid conditions. Moreover, the batch-K _d (22.7 m³/kg) at the standard L/S (4 mL/g) recommended by ASTM D 4319 was over an order of magnitude larger than the average column-K _d.     

仿生制备有机-无机复合微囊固定化葡萄糖氧化酶

将层层自组装技术与仿生矿化技术相结合,由聚苯乙烯磺酸钠、聚二甲基二烯丙基氯化铵和二氧化硅成功制备(聚苯乙烯磺酸钠-聚二甲基二烯丙基氯化铵)₂-二氧化硅复合微囊.采用扫描电子显微镜、红外光谱和热重对微囊的形貌和化学结构进行了表征.以该复合微囊作为理想载体固定化葡萄糖氧化酶.结果表明,固定于复合微囊中的葡萄糖氧化酶的热稳定性、pH稳定性、操作稳定性得到了提高;在最适条件下,复合微囊固定化葡萄糖氧化酶的酶活回收率为72.85%,米氏常数是游离葡萄糖氧化酶的2.21倍.复合微囊在化学/生物催化、药物/基因传递系统和生物传感器应用方面具有一定的潜能.     

奎宁-杂多酸杂化催化剂催化H2O2为氧源的苯羟基化反应

将奎宁与Keggin结构磷钼钒杂多酸结合制备出一种新颖的多相苯羟基化杂化催化剂, 采用傅里叶变换红外光谱、紫外-可见光谱、X射线衍射、扫描电镜、热重、N₂吸附-脱附和CHN元素分析等表征手段对催化剂进行了分析. 结果表明, 该催化剂是一种具有较高比表面积和孔体积的半无定形有机杂多酸盐. 在H₂O₂为氧源的苯羟基化反应中, 杂化催化剂引导了液-固两相催化体系, 表现出较高催化活性和重复使用稳定性. 催化剂中奎宁与杂多阴离子间的氢键和电子相互作用赋予了其高熔点和难溶性, 而高比表面积和因奎宁而改善的杂多阴离子的氧化还原性是其获得优异催化性能的主要原因. 这为多相苯羟基化反应提供了一种新的且制备便捷的基于多金属氧酸盐的高效催化剂.     

Surface Performance and Cytocompatibility Evaluation of Acrylic Acid-Mediated Carboxymethyl Chitosan Coating on Poly(tetrafluoroethylene-co-hexafluoropropylene)

To improve the biocompatibility of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film, a technique based on Ar plasma pretreatment and UV-induced grafting polymerization was used to immobilize carboxymethyl chitosan (CMCS) on the FEP film surfaces. Initially Ar plasma was used to treat FEP film. Then, plasma treated FEP film was modified via UV-induced grafting polymerization with hydrophilic acrylic acid (AAc) monomer. The following immobilization of CMCS on the FEP-pAAc surface was carried out via an amidation reaction. The change of chemical composition and surface morphology of FEP film were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Results of water contact angles measurement showed that the hydrophilicity of the surface has improved significantly after surface modification. Furthermore, methyl thiazolyl tetrazolium (MTT) assay and cell morphology analysis confirmed that mouse fibroblasts (L929 cells) attachment and proliferation were improved remarkably on the modified FEP surface. These results suggest that CMCS were successfully employed to surface engineering FEP film, and enhanced its cell biocompatibility. The approach presented here may be exploited for surface modification of biomaterials.     

Isolation and Characterization of Urethanase from Penicillium variabile and Its Application to Reduce Ethyl Carbamate Contamination in Chinese Rice Wine

A strain with urethanase activity was isolated from mouse gastrointestine. By combination of morphological characterization of the colony, hyphae, and spore and the sequence analysis of its rDNA ITS, the strain was determined as Penicillium variabile and named as P. variabile JN-A525. The enzymatic properties of urethanase from P. variabile JN-A525 were further studied. The optimum temperature and pH value of urethanase are of 50 °C and 6.0, respectively. The enzyme maintains stability when the temperature is below 50 °C and the pH is in the range of 7.0–10.0. The enzyme also exhibits ethanol tolerance. It can remove ethyl carbamate from Chinese rice wine without the change of flavor substances in the wine.     

Highly accurate and simple analytical approach to nonlinear Poisson–Boltzmann equation

A novel method is suggested to analytically solve a nonlinear Poisson–Boltzmann (NLPB) equation. The method consists chiefly of reducing the NLPB equation to linear PB equation in several segments by approximating a free term of the NLPB equation by piecewise linear functions, and then, solving analytically the linear PB equation in each segment. Superiority of the method is illustrated by applying the method to solve the NLPB equation describing a colloid sphere immersed in an arbitrary valence and mixed electrolyte solution; extensive test indicates that the resulting analytical expressions for both the electrical potential distribution Ψ (r) and surface charge density/surface potential relationship (σ/Ψ ₀) are characterized with two properties that mathematical structures are much simpler than those previously reported and application scope can be arbitrarily wide by adjusting the linear interpolation range. Finally, it is noted that the method is “universal” in that its applications are not limited to the NLPB equation.     

Enantioselective extraction of hydrophilic 2-chloromandelic acid enantiomers by hydroxypropyl-��-cyclodextrin: experiments and modeling

Enantioselective extraction of hydrophilic 2-chloromandelic acid (CMA) enantiomers from organic to aqueous phase with hydroxypropyl-??-cyclodextrin (HP-??-CD) as the selector was investigated. Equilibrium of the extraction system was modeled using a reactive extraction model with a homogeneous aqueous phase reaction. The influence of important process variables on the extraction efficiency, such as the type of the organic solvent and ??-cyclodextrin derivatives (??-CDs), concentration of the selector, pH and temperature, was investigated by experiment and modeling. Important parameters of this model were determined experimentally. Results showed that the experimental data agree with the model prediction perfectly and the model was further applied to accurately predict the extraction efficiency influenced simultaneously by pH and the concentration of HP-??-CD. Combining the experiment and the model data, the best extraction conditions were: pH of 2.5, HP-??-CD concentration of 0.05 mol L^?1, and temperature of 5°C, providing the enantioselectivity of 1.285 and the performance factor (pf) of 0.011.     

A facile one-pot, three-component synthesis of 3,3′-(4-arylpyridine-2,6-diyl)bis(2H-chromen-2-one) derivatives under microwave irradiation

A series of 3,3′-(4-arylpyridine-2,6-diyl)bis(2H-chromen-2-one) derivatives have been synthesized by the one-pot, three-component reaction of 3-acetylcoumarin, an aromatic aldehyde, and ammonium acetate in acetic acid under microwave irradiation. This procedure has the major advantages of short reaction time, good yields, low energy consumption, easy operation, and environmental friendliness. All of the products were characterized by IR and NMR spectroscopy, MS, and elemental analysis.     

A novel synthetic method for preparation of some folates

An improved method was developed for preparation of 5,6,7,8-tetrahydrofolic acid (THF) and calcium-5-methyltetrahydrofolate (5-MTHF-Ca) by reduction of folic acid using KBH₄ catalyzed by Pb(NO₃)₂. The yields of THF and 5-MTHF-Ca were 56.5 and 42.7 %, respectively. A convenient method for measurement of THF and 5-MTHF-Ca using liquid chromatography–mass spectrometry (LC–MS) was also established, enabling analysis of those folates within 10 min without application of gradient elution.     

Terbinafine hydrochloride intercalated in montmorillonite: synthesis and characterization

The novel antifungal hybrid of terbinafine hydrochloride (TER-HCl)/montmorillonite was synthesized by the intercalation method under mechanical stirring. Intercalation of TER-HCl in the MMT galleries was characterized by X-ray diffraction (XRD), Fourier transform infrared spectra, elemental analysis (EA). and thermogravimetric analysis (TGA). The results from IR, TGA, and EA showed a difference in chemical composition of the MMT and the TER-HCl/MMT. XRD analysis showed that the basal spacing of montmorillonite significantly expanded from 1.53 to 2.79 nm. TER-HCl was successfully intercalated into the interlayer of MMT, and 28 % of TER-HCl was released after 48 h in 0.9 % (w/v) NaCl aqueous solution (pH 7) at 37 ± 0.5 °C. The antifungal activity of the hybrid against Candida albicans was evaluated using the inhibitory zone method and the minimum inhibitory concentration. The TER-HCl/MMT strongly inhibited C. albicans. These results show that TER-HCl/MMT can be useful in biomedical applications.