Penicillin G acylase (PGA) was immobilized on magnetic Fe3O4@chitosan nanoparticles through the Schiff base reaction. The immobilization conditions were optimized as follows: enzyme/support 8.8 mg/g, pH 6.0, time 40 min, and temperature 25°C. Under these conditions, a high immobilization efficiency of 75% and a protein loading of 6.2 mg/g-support were obtained. Broader working pH and higher thermostability were achieved by the immobilization. In addition, the immobilized PGA retained 75% initial activity after ten cycles. Kinetic parameters Vmax and Km of the free and immobilized PGAs were determined as 0.91 mmol/min and 0.53 mmol/min, and 0.68 mM and 1.19 mM, respectively. Synthesis of amoxicillin with the immobilized PGA was carried out in 40% ethylene glycol at 25°C and a conversion of 72% was obtained. These results showed that the immobilization of PGA onto magnetic chitosan nanoparticles is an efficient and simple way for preparation of stable PGA.

Recently there has been a wide concern on inorganic nanoparticles as drug delivery carriers. CaCO₃ particles have shown promising potential for the development of carriers for drugs, but little research had been performed regarding their safe dosage for maximizing the therapeutic activity without harming biosystems. In this study, we assessed the biological safety of porous spherical CaCO₃ microparticles on Hela cells. The reactive oxygen species (ROS), glutathione (GSH), carbonyl content in proteins (CCP), DNA-protein crosslinks (DPC) and cell viability were measured. Results showed that with the exposure concentration increase, ROS and CCP in Hela cells presented a significant increase but GSH contents in Hela cells and cell viability showed a significant decrease respectively compared with the control. DPC coefficient ascended, but no statistically significant changes were observed. The results indicated that porous spherical CaCO₃ microparticles may induce oxidative damage to Hela cells. But compared with other nanomaterials, porous spherical CaCO₃ appeared to have good biocompatibility. The results implied that porous spherical calcium carbonate microparticles could be applied as relatively safe drug vehicles, but with the caveat that the effect of high dosages should not be ignored when attempting to maximize therapeutic activity by increasing the concentration

SUMMARY The hydrogen storage properties of Ti1−xScxMnCr (x = 0.05, 0.10, 0.15, 0.22, 0.27 and 0.32) alloys are studied by pressure‐composition isotherms at 0–60 °C and 1 kPa–4 MPa. The relevant crystal structures of the alloys and their hydrides are examined by the X‐ray diffraction and electron microscopy. The alloys are basically C14 type Laves phase with slightly different lattice parameters owing to the difference in composition. Except for x = 0.05 alloy, the bulk samples of these alloys can be easily activated under ambient conditions and attain the maximum hydrogen storage capacities during the initial hydrogenation. As Sc content increases, the hydrogen storage capacity of the alloy increases whereas the pressure of the absorption/desorption plateau decreases. No hydrogen‐induced disproportionation is observed, and the hydrogen‐induced defects and pulverization are not severe after hydriding/dehydriding cycles of these alloys. The Ti0.78Sc0.22MnCr alloy exhibits the best reversible hydrogen storage capacity of ~2 wt% in between 1 and 4000 kPa at room temperature. Except for the x = 0.32 alloy, the average thermodynamic values of |ΔH| and |ΔS| in the system increase approximately linearly with Sc content in the alloys. The thermogravimetry‐differential scanning calorimetry (TG‐DSC) on desorption of the hydride of Ti0.68Sc0.32MnCr indicates that the thorough release of hydrogen in the alloy can be achieved at 658 K. Copyright © 2012 John Wiley & Sons, Ltd.

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The aim of this study is to understand the homogeneous vapor-phase reactions in lignocellulosic biomass pyrolysis by using two separated reactors combined with an advanced analytical technique. The fast pyrolysis of elm was conducted in a microfluidized-bed reactor (MFBR) at 500 °C. The formed pyrolysis tar would be immediately introduced into a secondary tubular reactor (STR), in which the secondary reactions occurred and their product components were monitored by a photoionization mass spectrometry in real time. The mass yields of solids, condensables, and gases with different secondary reactions were measured. Meanwhile, the aerosol particles (>2.0 μm) were collected and their components that can be dissolved in methanol were characterized by GC−MS/FID. The results show that secondary reactions became active only when the temperature was higher than 500 °C. Temperature and residence time (RT) have a combined effect on secondary reactions (e.g., mass balance, tar composition, etc.) and the formation of polycyclic aromatic hydrocarbons (PAHs). The temperature is critical to the secondary reactions, in which, however, the long RT would contribute to decreasing the required temperature and to the formation of large PAHs. Furthermore, the possible routes for PAHs formation were proposed and the reaction conditions that impact them are also discussed.