Synthesis and Crystal Structure Characterization of Oxysilicate Apatites for Stabilization of Sr and Rare‐Earth Elements

Strontium (Sr) containing rare‐earth oxysilicate apatite A^I₄A^II₆(SiO₄)₆O₂ is considered a good matrix to accommodate radionuclide as its cation sites can incorporate lanthanide elements other than Sr. Here, we report a study on the synthesis of Nd₈Sr₂(SiO₄)₆O₂ and Yb₈Sr₂(SiO₄)₆O₂, which adopt P6₃/m apatite symmetry, as well as the characterization of crystallographic structures using X‐ray diffraction and electron microscopy. It is found that A^I position is shared by Nd, Yb and Sr, and A^IO₆ polyhedra are face‐connected, forming column structures, which are linked to SiO₄ tetrahedra, creating continuous channels. The Rietveld refinement shows that Nd and Yb prefer the A^II position in the channel. The twisted angle of adjacent triangle faces in an A^I‐O polyhedron along [001] is a critical parameter to identify the channel volume and its value varies when different cations are incorporated. The twisted angles for Nd‐apatite and Yb are 24.2° and 22.7° The findings provide a new insight into nuclear waste stabilization by apatite‐type structure.     

A Novel Technology for Natural Gas Conversion by Means of Integrated Oxidative Coupling and Dry Reforming of Methane

A novel process concept for the oxidative coupling of methane followed by the oligomerization to liquids has been developed within the frame of the EU integrated project OCMOL. This technology is based on process intensification principles via cutting‐edge structured microreactor technology. It is also a fully integrated industrial process through the re‐use and the recycling of by‐products, in particular CO₂, at every process stage. The focus of this contribution is on the reaction engineering aspects of the core steps, i.e., catalysts, kinetics and reactor design for the methane coupling and reforming.     

Physical aging in polymers: Comparison of two ways of determining narayanaswamy's parameter

In this work, we have investigated by differential scanning calorimetry the enthalpy relaxation of two poly[methyl(α-n-alkyl)acrylates] in which it is possible to change the length of the two alkyl chains. In particular, we have evaluated the Narayanaswamy parameter, which controls relative contribution of temperature and of structure to the relaxation times, by two methods: Grenet's method (GM) and the peak-shift method (PSM). The data obtained show that both methods lead to equivalent results. Nevertheless, PSM requires fewer experiments than GM, and PSM appears to be more practical. The results obtained on the two acrylates show that the parameter x increases with the lateral chain length, that is to say, that the temperature effects increase as the length of the alkyl chain is increased.     

The catalysis of the Ruff oxidative degradation of aldonic acids by titanium‐containing zeolites

Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Lipid Oxidation in Oil‐in‐Water Emulsions: Involvement of the Interfacial Layer

More polyunsaturated fats in processed foods and fewer additives are a huge demand of public health agencies and consumers. Consequently, although foods have an enhanced tendency to oxidize, the usage of antioxidants, especially synthetic antioxidants, is restrained. An alternate solution is to better control the localization of reactants inside the food matrix to limit oxidation. This review establishes the state‐of‐the‐art on lipid oxidation in oil‐in‐water (O/W) emulsions, with an emphasis on the role of the interfacial region, a critical area in the system in that respect. We first provide a summary on the essential basic knowledge regarding (i) the structure of O/W emulsions and interfaces and (ii) the general mechanisms of lipid oxidation. Then, we discuss the factors involved in the development of lipid oxidation in O/W emulsions with a special focus on the role played by the interfacial region. The multiple effects that can be attributed to emulsifiers according to their chemical structure and their location, and the interrelationships between the parameters that define the physicochemistry and structure of emulsions are highlighted. This work sheds new light on the interpretation of reported results that are sometimes ambiguous or contradictory.     

Effect of Free or Encapsulated Recombinant Aminopeptidase of Lactobacillus rhamnosus S93 on Acceleration of Cheddar Cheese Ripening

The use of recombinant aminopeptidase (PepN) from Lactobacillus rhamnosus S93 in free or encapsulated form was investigated to shorten the duration of Cheddar cheese ripening. Proteolysis was determined by measuring the soluble nitrogen as phosphotungstic acid (PTA-N) derivatives and free amino acids (FAA) over a 6-month period. The experimental cheeses received higher scores for sensory properties than the control cheese. The amounts of PTA-N and total FAA in the cheese with the encapsulated enzyme after 2 months of ripening were close to those of the control cheese after 6 months, suggesting the acceleration in proteolysis by about 4 months.     

Oregano: chemical analysis and evaluation of its antimalarial, antioxidant, and cytotoxic activities

Abstract: GC‐FID and GC‐MS analysis of essential oil from oregano leaves (Origanum compactum) resulted in the identification of 46 compounds, representing more than 98% of the total composition. Carvacrol was the predominant compound (36.46%), followed by thymol (29.74%) and p‐cymene (24.31%). Serial extractions with petroleum ether, ethyl acetate, ethanol, and water were performed on aerials parts of Origanum compactum. In these extracts, different chemical families were characterized: polyphenols (gallic acid equivalent 21.2 to 858.3 g/kg), tannins (catechin equivalent 12.4 to 510.3 g/kg), anthocyanins (cyanidin equivalent 0.38 to 5.63 mg/kg), and flavonoids (quercetin equivalent 14.5 to 54.7 g/kg). The samples (essential oil and extracts) were subjected to a screening for antioxidant (DPPH and ABTS assays) and antimalarial activities and against human breast cancer cells. The essential oil showed a higher antioxidant activity with an IC₅₀= 2 ± 0.1 mg/L. Among the extracts, the aqueous extract had the highest antioxidant activity with an IC₅₀= 4.8 ± 0.2 mg/L (DPPH assay). Concerning antimalarial activity, Origanum compactum essential oil and ethyl acetate extract showed the best results with an IC₅₀ of 34 and 33 mg/mL, respectively. In addition, ethyl acetate extract (30 mg/L) and ethanol extract (56 mg/L) showed activity against human breast cancer cells (MCF7). The oregano essential oil was considered to be nontoxic.     

Infrared study of nitrogen monoxide adsorption on palladium ion-exchanged ZSM-5 catalysts

The adsorption of NO at room temperature on a H-ZSM-5 catalyst exchanged with Pd(NH₃) ₄ ²⁺ complex and activated in oxygen at 773 K has been examined by FTIR spectroscopy. After the oxidizing treatment, the Pd tetrammine complex decomposed into Pd(II) ions and/or Pd(II) hydroxyl complexes dispersed in the zeolite channels. The subsequent adsorption of NO at room temperature led to the reduction of Pd(II) to Pd(I) entities, resulting in the formation and adsorption of NO₂ on H-ZSM-5. The Pd(I) entities were shown to adsorb NO and form mononitrosyl complexes dispersed in the zeolite porosity and characterized by a single infrared absorption band at 1881 cm^–1. The Pd(I) mononitrosyl complex was shown to reversibly coordinate water and NO₂ molecules. The resulting nitrosyl complex was characterized by a single NO vibration band at 1836 cm^–1.     

Hyperthermostabilization of Bacillus licheniformis{alpha}-amylase and modulation of its stability over a 50{degrees}C temperature range

Bacillus licheniformis