Much work has been done on the subject of what happens to software architecture during maintenance activities. There seems to be a consensus that it degrades during the evolution of the software. More recent work shows that this degradation occurs even during development activities: design decisions are either adjusted or forgotten. Some studies have looked into the causes of this degradation, but these have mostly done so at a very high level. This study examines three projects at code level. Three architectural pre-implementation designs are compared with their post-implementation design counterparts, with special attention paid to the causes of the changes. We found many negative changes causing anti-patterns, at the package, class, and method levels. After analysis of the code, we were able to find the specific reasons for the poor design decisions. Although the underlying causes are varied, they can be grouped into three basic categories: knowledge problems, artifact problems, and management problems. This categorization shows that anti-pattern causes are varied and are not all due to the developers. The main conclusion is that promoting awareness of anti-patterns to developers is insufficient to prevent them since some of the causes escape their grasp.
Feruloyl esterases (FAEs) and acetyl xylan esterases (AXEs) are important enzymes for plant biomass degradation and are both present in Carbohydrate Esterase family 1 (CE1) of the Carbohydrate‐Active enZymes database. In this study, ten novel fungal CE1 enzymes from different subfamilies were heterologously produced and screened for their activity towards model and complex plant biomass substrates. CE1_1 enzymes possess AXE activity, while CE1_5 enzymes showed FAE activity. Two enzymes from CE1_2 and one from CE1_5 possess dual feruloyl/acetyl xylan esterase (FXE) activity, showing expansion of substrate specificity. The new FXEs from CE1 can efficiently release both feruloyl and acetyl residues from feruloylated xylan, making them particularly interesting novel components of industrial enzyme cocktails for plant biomass degradation.
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