Skin tribology: Science friction?

The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch. The question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy? In other words: Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction? This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional methods. Skin tribology requires in vivo, subject and anatomical location specific test methods. Current predictive friction models can only partially be applied to predict in vivo skin friction. The reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions. A recently developed model gives the building blocks for enhanced understanding of friction at the micro scale. Only largely simplified power law based equations are currently available as general engineering tools. Finally, the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and comfort. Surface texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the produc

Getting a Grip

Cutlery design undergoes extensive evaluation of hand-object interaction, leading to improved products for people with hand use limitation

Preoperative upper tract invasive diagnostic modalities are associated with intravesical recurrence following surgery for upper tract urothelial carcinoma : A population-based study

Introduction &amp; Objectives: Evidence based mainly on small retrospective series points to an increased risk of intravesical recurrence (IVR) after preoperative diagnostic ureteroscopy (URS) in upper tract urothelial carcinoma (UTUC). We investigated if preoperative invasive diagnostic modalities (IDM) are associated with IVR after radical surgery for UTUC. Secondly, risk of death from urothelial cancer and all causes was investigated.Materials &amp; Methods: We investigated a population-based cohort of 1038 consecutive patients subjected to radical surgery for UTUC 2015–2019 in Sweden, using the Bladder Cancer Data Base Sweden (BladderBaSe 2.0), comprising all patients in the Swedish National Registry of Urinary Bladder Cancer. Risk estimates of IVR, death from urothelial cancer, and all causes following IDM (antegrade/retrograde uretero-pyelography and/or selective urine cytology/barbotage, and URS with or without concomitant biopsy) was assessed using multivariable Cox regression models adjusted for age, gender, clinical tumour stage, tumour location (renal pelvis/ureter/both), ipsilateral bladder cuff excision, previous bladder cancer, comorbidity, and educational level.Results: The study included 536 cases with and 502 without preoperative IDM. IDM was associated with increased risk of IVR (HR 1.24, 95% CI 1.03-1.52) and risk of urothelial cancer death (HR 1.56, CI 1.12-2.18), compared to no IDM after a median follow-up of 1.3 yrs. Stratified analysis for tumor location showed that IDM was associated with risk of IVR in ureteric cancer (HR 1.66, 95% CI 1.21-2.28) but not in renal pelvic cancer (HR 1.07, 95% CI 0.81-1.41). Limitations include the observational setting and the lack of information on tumour grade, multifocality and preoperative hydronephrosis.Conclusions: Worse outcomes for patients subjected to preoperative IDM highlight the need for carefully considering diagnostic decisions for UTUC patients, specifically in tumours located in the ureter.</p