Nanoconfined (Bio)Catalysts as Efficient Glucose‐Responsive Nanoreactors

Herein, the design, synthesis, and characterization of bifunctional hybrid nanoreactors used for concurrent one‐pot chemoenzymatic reactions are shown. In the design, the enzyme, glucose oxidase, is wrapped with a peroxidase‐mimetic catalytic polymer. Hemin, the organic catalyst, is linked to the flexible polymeric scaffold through coordination to the imidazole groups that hang out the network. This spatial arrangement, which works as a metabolic channel, is optimized for cooperative chemoenzymatic reactions in which the enzyme catalyzes first. A deep characterization of the integrated nanoreactors demonstrates that the confinement of two distinct catalytic sites in the nanospace is very effective in one‐pot reactions. Moreover, besides its role as scaffold material, the polymeric mantel protects both the biocatalyst and the chemical catalyst from degradation and inactivation in the presence of organic solvents. Furthermore, the polymeric environment of the nanoreactors can be tailored in order to trigger the assembly of those into highly active heterogeneous hybrid catalysts. Finally, the new nanoreactors are applied to the efficient degradation of organic aromatic compounds using glucose as the only fuel.     

Design of tailored biodegradable implants: The effect of voltage on electrodeposited calcium phosphate coatings on pure magnesium

Magnesium, as a biodegradable metal, offers great potential for use as a temporary implant material, which dissolves in the course of bone tissue healing. It can sufficiently support the bone and promote the bone healing process. However, the corrosion resistance of magnesium implants must be enhanced before its application in clinical practice. A promising approach of enhancing the corrosion resistance is deposition of bioactive coating, which can reduce the corrosion rate of the implants and promote bone healing. Therefore, a well-designed substrate-coating system allowing a good control of the degradation behavior is highly desirable for tailored implants for specific groups of patients with particular needs. In this contribution, the influence of coating formation conditions on the characteristics of potentiostatically electrodeposited CaP coatings on magnesium substrate was evaluated. Results showed that potential variation led to formation of coatings with the same chemical composition, but very different morphologies. Parameters that mostly influence the coating performance, such as the thickness, uniformity, deposits size, and orientation, varied from produced coating to coating. These characteristics of CaP coatings on magnesium were controlled by coating formation potential, and it was demonstrated that the electrodeposition could be a promising coating technique for production of tailored magnesium-CaP implants.     

Aging of novel membranes made of PVA and cellulose nanocrystals extracted from Egyptian rice husk manufactured by compression moulding process

Novel membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) originated from Rice Husk (RH), Glutaraldehyde (GLA) and Glycerine (G) were manufactured by the compression moulding process. Rice husk is a new source to isolate pure cellulose nanocrystals via mechanical and chemical treatment. The biodegradability of the membranes has been evaluated using UV accelerated weathering as well as a soil burial test. The morphology of membranes (PVA/RH-CNCs) was characterized by using the Scanning Electron Microscope (SEM). The chemical structure of the membranes (PVA/RH-CNCs) was characterised by Fourier-Transformation Infrared (FTIR) spectroscopy as well as wide-angle X-ray diffraction. The mechanical properties of the membranes were evaluated using standard techniques. Swelling and weight loss resulting from biodegradation were also evaluated. The results showed that the developed transient membranes can be used as food packaging bags owing to biodegradability (weight loss) under irradiation and during soil burial.     

化学品生物降解的评价方法

本文介绍了化学品生物降解的定义、化学品在微生物中的曝露实验的方法,总结了有机物好氧生物降解和厌氧生物降解的评价方法。最后介绍了难于生物降解的“三致”型(致癌、致畸、致突变)有机污染物的降解方法,为污染物的降解提供了参考。     

A study of external mass transfer effect on biodegradation of phenol using low‐density polyethylene immobilized Bacillus flexus GS1 IIT (BHU) in a packed bed bioreactor

The impact of external mass transport on the biodegradation rate of phenol in a packed bed bioreactor (PBBR) was studied. A potential bacterial species, Bacillus flexus GS1 IIT (BHU), was isolated from the petroleum‐contaminated soil. Low‐density polyethylene (LDPE) immobilized with the B. flexus GS1 IIT (BHU) was used as packing material in the PBBR. The PBBR was operated by varying the inlet feed flow rate from 4 to 10 mL/min, and the corresponding degradation rate coefficients were found to be in the range of 0.119–0.157 L/g h. In addition, the highest removal rate of phenol was obtained to be 1.305 mg/g h at an inlet feed rate of 10 mL/min. The external mass transfer was studied using the model . A new empirical correlation for the biodegradation of phenol in the PBBR was developed after the evaluation at various values of K and n.     

白腐真菌对煤炭的降解转化试验

通过正交试验研究了白腐真菌在煤炭降解转化过程中煤样粒度、菌液用量、降解作用时间等各因素对其降解率的影响.还对白腐真菌对煤降解转化产物进行了元素分析，在此基础上探讨了白腐菌对煤生物降解转化的规律.实验结果表明，白腐真菌对经硝酸预处理后的义马褐煤样有较强的降解作用，15 d的时间能把粒度-0.2 mm的经硝酸预处理的义马褐煤降解41.54%，降解作用主要是白腐真菌在培养过程中释放出来的酶作用的结果.     

The anaerobic degradation of detergent range fatty alcohol ethoxylates. Studies with C-labelled model surfactants

The anaerobic degradation of fatty alcohol polyglycol ethers was studied in a model sludge digester employing stearyl alcohol ethoxylate which was ¹⁴C-labelled either in the alkyl or in the heptaglycol chain. After 4-weeks' incubation of the ¹⁴C-compounds at 35°C in the presence of raw sludge as additional digestible substrate more than 80% of the initial radioactivity was found as methane and carbon dioxide. In addition, the major part of radioactivity in the digested sludge, corresponding to nearly 10% of added ¹⁴C, was attributable to biomass so that ultimate degradation of the two model surfactants amounted to more than 90%. Analysis of the small fraction of radiolabelled metabolites in the sludge supernatant allowed conclusions with regard to the anaerobic degradation route of linear alcohol ethoxylates. After primary biodegradation of the surfactant molecule by scission into the alkyl and poly(ethylene glycol) moieties the further biodegradation of the latter seems to proceed as under aerobic conditions, i.e. via oxidative or hydrolytic depolymerization steps. Eventually, ultimate biodegradation of the obtained monomers (C₂-units) leads to the formation of the gaseous end products.