Search results for "Biomedical engineering"

Cytotoxicity investigations of plasma sprayed calcium phosphate coatings

1994

One potential alternative material to replace hydroxyapatite (HAp) as a coating material for plasma-sprayed coatings on implants for hip replacement is fluorapatite (FAp). FAp has advantages over HAp regarding the capability of being chemically stable during the coating process. This leads to surface coatings containing high apatite rates with a mechanical stability (bond strength, microhardness) comparable to HAp. From the technical point of view the production of FAp coatings is well investigated, although studies on biocompatibility of FAp coatings are fewer. This paper reports the production of HAp and FAp coatings with varying solubilities by plasma spraying and their in vitro cytotoxi…

Spacers and Valved Holding Chambers—The Risk of Switching to Different Chambers

2020

© 2020 The Authors. Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Non-uniformity of displacement and strain within the Achilles tendon is affected by joint angle configuration and differential muscle loading.

2020

Although the Achilles tendon (AT) has been studied for more than a century, a complete understanding of the mechanical and functional consequences of AT structural organization is currently lacking. The aim of this study was to assess how joint angle configuration affects subtendon displacement and strain of soleus (SOL) and lateral gastrocnemius (LG) muscles. Knots sutured onto SOL and LG subtendons of 12 Wistar rats, were videotaped to quantify displacements and the ankle torque was assessed for different isometric activation conditions (i.e., individual and simultaneous) of the triceps surae muscles. Changing ankle and knee joint angle affected the magnitude of displacement, relative dis…

Mechanical Coupling Between Muscle-Tendon Units Reduces Peak Stresses

2017

The presence of mechanical linkages between synergistic muscles and their common tendons may distribute forces among the involved structures. We review studies, using humans and other animals, examining muscle and tendon interactions and discuss the hypothesis that connections between muscle bellies and within tendons may serve as a mechanism to distribute forces and mitigate peak stresses. peerReviewed

Transparency in transactive energy at distribution level

2017

A recent report from the German Energy Agency analyzes the possible introduction of the blockchain technology in energy transactions in power distribution. The issue deserves attention since the extensive digitalization of business models puts new challenges to utilities in the power sector. The German decision makers in the energy field claim that blockchain appears as a close perspective and, at the same time, the Gartner hypecycle puts this technology at the peak of inflated expectations in 2016. Diffuse perception however provides hints for further investigation on the topic. This paper provides insight into the problem of peer-to-peer energy exchange from a technical perspective, provi…

Clinical evaluation of automated capillary refill time estimation in dogs and cats

2019

In this study, we clinically evaluated a pulse oximeter-based device for automated capillary refill time (CRT) estimation in dogs and cats. CRT can reveal conditions like shock or anemia in dogs and cats. However, visual CRT estimation has low repeatability, and the available optical systems for automated estimation are not suitable for pets. We evaluated a custom-made portable CRT measuring device on various measurement sites of 12 dogs and 11 cats with parallel visual CRT estimation on the gum by treating veterinarian. The capillary refill was also recorded by a video camera for reference. The visual and video procedures were moderately correlated with the coefficient of 0.61; visual CRT …

The role of expert evaluation for microsleep detection

2015

Abstract Recently, it has been shown by overnight driving simulation studies that microsleep density is the only known sleepiness indicator which rapidly increases within a few seconds immediately before sleepiness related crashes. This indicator is based solely on EEG and EOG and subsequent adaptive pattern recognition. Accurate microsleep recognition is very important for the performance of this sleepiness indicator. The question is whether expensive evaluations of microsleep events by a) experts are necessary or b) non-experts provide sufficient evaluations. Based on 11,114 microsleep events in case a) and 12,787 in case b) recognition accuracies were investigated utilizing (i) artificia…

2021

The present study was conducted with the aim of constructing and validating a short form of the Profile of Mood States (POMS). The POMS is a widely-applied measure for the assessment of an individual's mood. Thus, it is of great relevance for many research questions in clinical and social psychology. To develop the short scale, we first examined psychometric properties and found the optimal 16-item solution among all valid combinations of the full POMS in an exploratory subsample (n = 1,029) of our complete representative sample of the German general population. We then validated this model in a confirmatory subsample (n = 977). Additionally, we examined its invariance across age groups and…

2021

(1) Background: This cross-sectional study aims to compare a new and non-invasive approach using hyperspectral imaging (HSI) with the conventional modified Allen’s test (MAT) for the assessment of collateral perfusion prior to radial forearm free flap harvest in healthy adults. (2) HSI of the right hand of 114 patients was recorded. Here, three recordings were carried out: (I) basic status (perfusion), (II) after occlusion of ulnar and radial artery (occlusion) and (III) after releasing the ulnar artery (reperfusion). At all recordings, tissue oxygenation/superficial perfusion (StO2 (0–100%); 0–1 mm depth), tissue hemoglobin index (THI (0–100)) and near infrared perfusion index/deep perfusi…

Imaging photoplethysmography for evaluation of cutaneous sensory nerve fiber function

2020

Peripheral neuropathy refers to peripheral nervous system dysfunction which affects up to 2% of the world's population. This condition is caused by damage to the small nerve fibers, hence its assessment is still challenging due to the lack of simple, non-invasive and objective diagnostic techniques. The present study aimed to develop and evaluate a simple, objective and non-invasive technique for assessment of small cutaneous sensory nerve fiber function. Our approach is based on utilization of imaging photoplethysmography and local skin heating. The effectiveness of the method was evaluated on young, healthy volunteers (n = 14) after 10 minutes of 45-degree local skin heating, while record…