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Requirements from WP123200
(2022)
Local inflammation plays a pivotal role in the process of secondary damage after spinal cord injury. We recently reported that acute intravenous application of extracellular vesicles (EVs) secreted by human umbilical cord mesenchymal stromal cells dampens the induction of inflammatory processes following traumatic spinal cord injury. However, systemic application of EVs is associated with delayed delivery to the site of injury and the necessity for high doses to reach therapeutic levels locally. To resolve these two constraints, we injected EVs directly at the lesion site acutely after spinal cord injury. We report here that intralesional application of EVs resulted in a more robust improvement of motor recovery, assessed with the BBB score and sub-score, as compared to the intravenous delivery. Moreover, the intralesional application was more potent in reducing inflammation and scarring after spinal cord injury than intravenous administration. Hence, the development of EV-based therapy for spinal cord injury should aim at an early application of vesicles close to the lesion.
Bone grafts can be engineered by differentiating human mesenchymal stromal cells (MSCs) via the endochondral and intramembranous ossification pathways. We evaluated the effects of each pathway on the properties of engineered bone grafts and their capacity to drive bone regeneration. Bone-marrow-derived MSCs were differentiated on silk scaffolds into either hypertrophic chondrocytes (hyper) or osteoblasts (osteo) over 5 weeks of in vitro cultivation, and were implanted subcutaneously for 12 weeks. The pathways' constructs were evaluated over time with respect to gene expression, composition, histomorphology, microstructure, vascularization and biomechanics. Hypertrophic chondrocytes expressed higher levels of osteogenic genes and deposited significantly more bone mineral and proteins than the osteoblasts. Before implantation, the mineral in the hyper group was less mature than that in the osteo group. Following 12 weeks of implantation, the hyper group had increased mineral density but a similar overall mineral composition compared with the osteo group. The hyper group also displayed significantly more blood vessel infiltration than the osteo group. Both groups contained M2 macrophages, indicating bone regeneration. These data suggest that, similar to the body's repair processes, endochondral pathway might be more advantageous when regenerating large defects, whereas intramembranous ossification could be utilized to guide the tissue formation pattern with a scaffold architecture.
Tapped inductor DC-to-DC converters are interesting circuits, the winding ratio of the two windings mounted on the same core change the voltage transformation ratio compared to the untapped inductor. The tapped inductor converters are especially useful, when high or low voltage transformation ratios have to be realized. The disadvantage of this concept is that the coupling between the two windings is not total and can be described by the stray or leakage inductance. This stray inductance leads to a high overvoltage at the active switch, and therefore also across other elements of the converter. After a short summery of the ideal tapped Boost converter, the design of an RCD snubber which limits the overvoltage is explained. To improve the efficiency of the converter two active snubber networks are treated, which feed the energy stored in the snubber capacitor into the input source or into the output circuit. Simulations are used to prove these considerations.
Two-Stage Step-up Converter with Different Voltage Transformation Ratios depending on the Duty Cycle
(2022)
A two-stage converter with high output voltage
ratio and reduced current stress of the inductors and partly
reduced voltage stress is discussed. The function is explained
with the help of voltage and current diagrams. The voltage
transformation ratio changes between a quadratic step-up for
duty cycles lower 0.5 and a double Boost converter for duty
cycles higher than 0.5. Dimensioning hints, the control law for
feed-forward controls, the transient when the supply is turned on
is discussed and some simulations are given. A comparison to
other two-stage converters is also treated.
Although various standards and guidelines for accessible design exist, many modern digital devices lack even basic accessibility features. In particular, touchscreens without haptic feedback and a highly complex menu navigation impose serious hurdles for many people – especially for people with disabilities and elderly persons. In this work, we present the Universal Access Panel (UAP) for enabling barrier-free access to home appliances and IoT devices. The system offers a novel, radically simple, multimodal user interface consisting of just a few interaction elements for accessing dedicated functions of the connected home. Using established APIs and communication protocols such as HomeConnect or OpenHab, various domestic appliances, consumer products and smart home devices can be controlled from a single, multimodal interaction console. The system has been designed in cooperation with visually impaired accessibility experts and a user study was conducted with people from the target group. The results show a high overall usability of the prototype.