On‐Site Identification of Early BÖTTGER Red Stoneware Made at Meissen Using Portable XRF: 1, Body Analysis

A selection of 50 red stoneware objects, polished, unpolished, partially polished or glazed, from different collections (Département du Patrimoine et des Collections de la Cité de la Céramique, Sèvres, France; Art Institute of Chicago; a private collection), attributed to 18th century Böttger, 20th century Meissen (Saxony) and Chinese productions have been analyzed with a portable X‐ray fluorescence spectrometer in museum/collector rooms. The comparison of major (Si, Al), minor (K,Ca,Fe), and trace (Ti, Mn, Zr, Rb, Sr) element ratios was made to assist with the classification of the different artifacts as a function of their production technology and raw materials. The results are discussed in light of historical reports on the characteristics of Böttger production and criteria of identification are proposed to distinguish between “classical” Böttger (early 18th century) and other productions.     

提高尿素产品质量的措施

本文叙述了当前的市场形势下,内蒙古人肥厂为提高尿素产品的质量,所采取的一系列产品质量控制办法,收到了明显的效果。     

Immobilization of the Aspartate Ammonia-Lyase from Pseudomonas fluorescens R124 on Magnetic Nanoparticles: Characterization and Kinetics

Aspartate ammonia-lyases (AALs) catalyze the non-oxidative elimination of ammonia from l -aspartate to give fumarate and ammonia. In this work the AAL coding gene from Pseudomonas fluorescens R124 was identified, isolated, and cloned into the pET-15b expression vector and expressed in E. coli. The purified enzyme (PfAAL) showed optimal activity at pH 8.8, Michaelis-Menten kinetics in the ammonia elimination from l -aspartate, and no strong dependence on divalent metal ions for its activity. The purified PfAAL was covalently immobilized on epoxy-functionalized magnetic nanoparticles (MNP), and effective kinetics of the immobilized PfAAL-MNP was compared to the native solution form. Glycerol addition significantly enhanced the storability of PfAAL-MNP. Inhibiting effect of the growing viscosity (modulated by addition of glycerol or glucose) on the enzymatic activity was observed for the native and immobilized form of PfAAL, as previously described for other free enzymes. The storage stability and recyclability of PfAAL-MNP is promising for further biocatalytic applications.