The anatomy of a comprehensive constrained, restrained refinement program for the modern computing environment-Olex2 dissected

This paper describes the mathematical basis for olex2.refine, the new refinement engine which is integrated within the Olex2 program. Precise and clear equations are provided for every computation performed by this engine, including structure factors and their derivatives, constraints, restraints and twinning; a general overview is also given of the different components of the engine and their relation to each other. A framework for adding multiple general constraints with dependencies on common physical parameters is described. Several new restraints on atomic displacement parameters are also presented

Contribution of C-beijerinckii and C-sporogenes in association with C-tyrobutyricum to the butyric fermentation in Emmental type cheese

The relationship between C. tyrobutyricum, C. sporogenes and C. beijerinckii in experimental cheese conditions, and their influences on late-blowing and butyric fermentation, have been investigated. A molecular approach using a PCR-TTGE method in combination with conventional methods, such as microbiological and physico-chemical analysis, was performed to monitor the evolution of these clostridial species, simultaneously with the occurrence of cheese defects. Sixteen Emmental type cheeses were produced from milk inoculated with different clostridial spore associations. In all cheeses inoculated with C. tyrobutyricum, obvious signs of late blowing were detected. In cheeses inoculated with C. beijerinckii or C. sporogenes, a formation of holes in cheese body was observed, with a concomitant slight amount of butyric acid production. Even though C. beijerinckii and C. sporogenes were less metabolically active and less numerically important than C. tyrobutyricum cheese as shown by TTGE profiles, the association of these species to C. tyrobutyricum enhanced the butyric fermentation and the cheese defects. The level of butyric content in ripened cheese increased to 268 mg 100 g(-1) in presence of C. tyrobutyricum, and reached a maximum of 414 mg 100 g(-1) in presence of the C. beijerinckii-C. tyrobutyricum (1:10) association. The propionic fermentation was also higher in cheese inoculated with C. tyrobutyricum, and was slowed down in presence of C. beijerinckii and C. sporogenes. From 30 days of ripening, a strong correlation between the chemical contents and the intensity of cheese defects was demonstrated. A chemical analysis of cheese associated with a molecular method for microbial spoilage investigation allows the prediction of the level of late blowing at early stages of ripening, and the understanding of the origin of the defect