On a New Method to Determine the Yield Stress in Lubricating Grease

An experimental study using both a controlled stress and a controlled strain rheometer has been undertaken to characterize lubricating grease in shear, creep, stress relaxation, and oscillatory flow, with a main focus on determining the yield stress. The yield stress was examined using a cone–plate and parallel-plate system with smooth and rough surfaces. Clear discrepancies were observed in the yield stress values obtained using different techniques where oscillatory strain sweep measurements seem to be the best choice. This technique is less sensitive to wall slip, shows good reproducibility, and is relatively easy to perform. The method also shows that the yield stress is a function of the imposed frequency and therefore of the time domain. At lower values of shear—that is, in the linear viscoelastic regime—there is no structural breakdown and the rheology of the grease can be described by the Maxwell model where the stress and the strain are almost proportional to each other. Based on this observation, a novel method to determine the yield stress is proposed: “The yield stress can be determined from the point where this linearity no longer applies.” This method is compared to those that are commonly used. The yield stress was found to depend exponentially on temperature and linearly on frequency

OCCUPATIONS AND DIGITAL CHALLENGES - A qualitative study about the implementation of digital work methods in dental care

Purpose: This research aims to study how a qualified professional occupation experiences the implementation of digitalized work methods in their daily work. More specifically, how dentist professionals respond to the digitalized work methods and identify challenges when implementing digital change in a professional context. Theory: The theoretical framework is based upon the institutional logics perspective. We aim to investigate how the respondents make sense of the organizational change and how these logics are implemented in practice; thus, we are also influenced by the sensemaking perspective. Method: The study takes a qualitative approach, and the empirical data is based on 22 interviews with general dentists and specialist dentists in a Swedish public dental care organization. Result: The result shows that the dentists responded with enthusiasm towards the change; however, skepticism was also prevalent. The study identifies several challenges that dentists encounter during the change process, for example, loss of autonomy and new challenges regarding knowledge sharing and communication. Further, a lack of coherence between the general dentists and specialist dentists was evident and may create tensions as the project progresses. Most respondents viewed this working method to be beneficial for either patients or organizational efficiency or, both