The role of the C-terminal Leu300 in maintaining thermal stabilityof the neutral protease of Bacillus subtilis was investigated.From model building studies based on the three dimensional structureof thermolysin, the neutral protease of B.thermoproteolyticus,it was conduded that this residue is located in a hydrophobicpocket composed of residues located in the C-terminal and themiddle domain. To test the hypothesis that Leu300, by contributingto a stabilizing interaction between these domains, is importantfor enzyme stability, several neutral protease mutants wereconstructed and characterized. The thermostability of the enzymewas lowered by deleting Leu300 or by replacing this residueby a smaller (Ala), a polar (Asn) or a sterically unfavourable(He) amino acid. Thermostabiity was increased upon replacingLeu300 by Phe. These results are in agreement with model-buildingstudies. The effects on thermostability observed after mutatingthe corresponding Val318 in the thermostable neutral proteaseof B.stearothermophilus were less pronounced. 相似文献
In designing sociotechnical systems, accounting for the phenomenon of self-organisation is critical. Empirical studies show that workers in these systems adapt not just their individual behaviours, but also their collective structures to deal with complex work environments. The concept of self-organisation can explain how such adaptations can be achieved spontaneously, continuously, and relatively seamlessly, and why this phenomenon is important for dealing with instability, uncertainty, and unpredictability in the task demands. However, existing design approaches such as resilience engineering and cognitive work analysis are limited in their capacity to design for self-organisation. This paper demonstrates that the diagram of work organisation possibilities, a recent addition to cognitive work analysis, provides a sound theoretical basis for designing for self-organisation. That is, it shows how essential components of the diagram are aligned with the concept of self-organisation and are well-grounded in empirical observations of adaptation in a variety of sociotechnical systems, specifically emergency management, military, and healthcare systems. Consequently, designs based on this diagram should have the potential to facilitate the emergence of new spatial, temporal, and functional organisational structures from the flexible actions of individual, interacting actors, thereby enhancing a system’s capacity for dealing with a dynamic, ambiguous work environment. Future research should focus on validating these ideas and demonstrating their value in industrial settings.
Scholars often follow a contingency approach to study which marketing activities are suitable for a particular type of product innovation project, thereby making a distinction between incremental and radical innovation only. ‘Moderately novel’ projects, which have intermediate levels of newness, have therefore not been given due attention. This paper focuses on market intelligence generation and the creation of cross‐functional linkages as marketing activities that are important in the context of moderately novel product innovation. In addition, the organizational position of the marketers involved in these activities is dealt with. Based on the analysis of four successful projects in the chemical industry, we argue, firstly, that moderately novel innovation projects have their own particular sets of marketing practices and, secondly, that differences exist between projects aiming at a new market segment and projects in which novelty is not related to market segment but to other market dimensions. These differences are especially salient in early project phases. These findings are pertinent to research on the role of marketers in product innovation, and to the study of organizational ambidexterity. 相似文献
Increasing numbers of hard environmental constraints are being imposed in urban traffic networks by authorities in an attempt to mitigate pollution caused by traffic. However, it is not trivial for authorities to assess the cost of imposing such hard environmental constraints. This leads to difficulties when setting the constraining values as well as implementing effective control measures. For that reason, quantifying the cost of imposing hard environmental constraints for a certain network becomes crucial. This paper first indicates that for a given network, such cost is not only related to the attribution of environmental constraints but also related to the considered control measures. Next, we present an assessment criterion that quantifies the loss of optimality under the control measures considered by introducing the environmental constraints. The criterion can be acquired by solving a bi-level programming problem with/without environmental constraints. A simple case study shows its practicability as well as the differences between this framework and other frameworks integrating the environmental aspects. This proposed framework is widely applicable when assessing the interaction of traffic and its environmental aspects. 相似文献
Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture. 相似文献