Comparing failure tests on pharmaceutical tablets: Interpretation using experimental results and a numerical approach with cohesive zone models

The mechanical strength is an important quality attribute of pharmaceutical tablets. It can be determined using different failure tests like the Brazilian test or the three-point bending test. Nevertheless, literature shows that different failure tests often give conflicting values of tensile strengths (TS), which are generally calculated using the maximum stress criterion as a failure criterion. This work started from the hypothesis that these discrepancies are in fact due to the application of this criterion which is not suited to study pharmaceutical tablets, first due to heterogeneity of the stress distributions during the tests and second due to the quasi-brittle nature of pharmaceutical tablets. As an alternative, a numerical fracture criterion which is known to be well-suited for quasi-brittle solids (cohesive zone model, CZM) was used and calibrated using experiments. Using this approach, the breaking forces obtained numerically were shown to be in fair agreement with the experimental ones. Above all, the numerical results made it possible to catch the trends when comparing the different failure tests one to another. Especially, the model made it possible to retrieve the factor 2 between the TS obtained by three-point bending and by diametral compression found in the literature

The phenome analysis of mutant alleles in Leucine-Rich Repeat Receptor-Like Kinase genes in rice reveals new potential targets for stress tolerant cereals

AbstractPlants are constantly exposed to a variety of biotic and abiotic stresses that reduce their fitness and performance. At the molecular level, the perception of extracellular stimuli and the subsequent activation of defense responses require a complex interplay of signaling cascades, in which protein phosphorylation plays a central role. Several studies have shown that some members of the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) family are involved in stress and developmental pathways. We report here a systematic analysis of the role of the members of this gene family by mutant phenotyping in the monocotyledon model plant rice, Oryza sativa. We have then targeted 176 of the ∼320 LRR-RLK genes (55.7%) and genotyped 288 mutant lines. Position of the insertion was confirmed in 128 lines corresponding to 100 LRR-RLK genes (31.6% of the entire family). All mutant lines harboring homozygous insertions have been screened for phenotypes under normal conditions and under various abiotic stresses. Mutant plants have been observed at several stages of growth, from seedlings in Petri dishes to flowering and grain filling under greenhouse conditions. Our results show that 37 of the LRR-RLK rice genes are potential targets for improvement especially in the generation of abiotic stress tolerant cereals

OryGenesDB: a database for rice reverse genetics

Insertional mutant databases containing Flanking Sequence Tags (FSTs) are becoming key resources for plant functional genomics. We have developed OryGenesDB (), a database dedicated to rice reverse genetics. Insertion mutants of rice genes are catalogued by Flanking Sequence Tag (FST) information that can be readily accessed by this database. Our database presently contains 44166 FSTs generated by most of the rice insertional mutagenesis projects. The OryGenesDB genome browser is based on the powerful Generic Genome Browser (GGB) developed in the framework of the Generic Model Organism Project (GMOD). The main interface of our web site displays search and analysis interfaces to look for insertions in any candidate gene of interest. Several starting points can be used to exhaustively retrieve the insertions positions and associated genomic information using blast, keywords or gene name search. The toolbox integrated in our database also includes an ‘anchoring’ option that allows immediate mapping and visualization of up to 50 nucleic acid sequences in the rice Genome Browser of OryGenesDB. As a first step toward plant comparative genomics, we have linked the rice and Arabidopsis whole genome using all the predicted pairs of orthologs by best BLAST mutual hit (BBMH) connectors