Improved Capacity Retention of SiO2_{2}-Coated LiNi0.6_{0.6}Mn0.2_{0.2}Co0.2_{0.2}O2_{2} Cathode Material for Lithium-Ion Batteries

Surface degradation of Ni-enriched layered cathode material Li[Ni0.6Mn0.2Co0.2]O2 (NMC622) is the main reason that leads to large capacity decay during long-term cycling. In the frame of this research, an amorphous SiO2 coating was applied onto the surface of the commercially available NMC622 powder by a wet coating process, through the condensation reaction of tetraethylorthosilicate. The chemical composition of the coating layer was analyzed by inductively-coupled plasma. The morphology was studied by scanning electron microscopy and transmission electron microscopy. Electrochemical properties, including cyclic voltammetry, galvanostatic cycling, and rate capability measurements in a half-cell configuration, were tested to compare the electrochemical behavior of the non-coated and coated NMC622 materials. It is shown that the rate performance of the NMC622 materials is not aected by the coating layer. After 700 cycles in the range of 3.0–4.3 V at 2 C discharge, the cells with SiO2-coated NMC622 materials retained 80% of their initial capacity, which is higher than the uncoated ones (74%). Physicochemical characterizations, e.g., XRD and SEM, were performed post-mortem to reveal the stabilizing mechanism of the SiO2-coated NMC622 electrodes after long-term cycling. Based on these results, this is due to the shielding effect of the coating between the NMC622 particle surface and the liquid electrolyte, along with its scavenging effect on HF. SiO2 coating is therefore a facile surface modification method that results in potentially significant enhancement of the cyclic stability of Ni-rich NMC materials

Towards an Explanatory Design Theory for Context-Dependent Learning in Immersive Virtual Reality

Immersive virtual reality (IVR) is increasingly used for learning. However, research on specific designs for IVRs which can be used to enhance individual learning performance is still at an early stage. In this research-in-progress paper, we build upon theories on context-dependent learning to develop an explanatory design theory. We hypothesize that if the user learns in a virtual environment that represents the recall environment (environmental congruence), recall is facilitated. Additionally, if the IVR is designed with a high degree of sensory immersion, the effect of environmental congruence on learning is further increased through enhanced cognitive absorption in the technology. In contrast, cognitive absorption in the task should have a reversed effect. To test the explanatory design theory, we plan to conduct a 2 (learning environment: Room A vs. Room B) x 2 (sensory immersion: low vs. high) x 2 (recall environment: Room A vs. Room B) between-subjects laboratory experiment

Heterodyn-Speckle-Interferometrie zur Schwingungsmessung

Eine Kombination aus Speckle-Interferometrie und Doppler-Yelocimetrie ermöglicht die Messung von Schwingungen bzw. Geschwindigkeiten an rauhen Oberflächen an mehreren Punkten gleichzeitig. Wir nennen dieses Verfahren Heterodyn-Speckle-lnterferometrie. Das Messprinzip ist das der Laser-Speckle-Interferometrie, die durch Einführung einer Lichtfrequenzverschiebung im Referenzstrahl dynamisiert wird. Dem Speckle-Bild des Messobjekts wird die Referenzwelle überlagert, gemessen wird die Frequenz der Intensitätsänderung in bestimmten Punkten des Bildes

Prognostic Relevance of the Eighth Edition of TNM Classification for Resected Perihilar Cholangiocarcinoma

Objectives: In our study, we evaluated and compared the prognostic value and performance of the 6th, 7th, and 8th editions of the American Joint Committee on Cancer (AJCC) staging system in patients undergoing surgery for perihilar cholangiocarcinoma (PHC). Methods: Patients undergoing liver surgery with curative intention for PHC between 2002 and 2019 were identified from a prospective database. Histopathological parameters and stage of the PHC were assessed according to the 6th, 7th, and 8th editions of the tumor node metastasis (TNM) classification. The prognostic accuracy between staging systems was compared using the area under the receiver operating characteristic curve (AUC) model. Results: Data for a total of 95 patients undergoing liver resection for PHC were analyzed. The median overall survival time was 21 months (95% CI 8.1–33.9), and the three- and five-year survival rates were 46.1% and 36.2%, respectively. Staging according to the 8th edition vs. the 7th edition resulted in the reclassification of 25 patients (26.3%). The log-rank p-values for the 7th and 8th editions were highly statistically significant (p ≤ 0.01) compared to the 6th edition (p = 0.035). The AJCC 8th edition staging system showed a trend to better discrimination, with an AUC of 0.69 (95% CI: 0.52–0.84) compared to 0.61 (95% CI: 0.51–0.73) for the 7th edition. Multivariate survival analysis revealed male gender, age >65 years, positive resection margins, presence of distant metastases, poorly tumor differentiation, and lymph node involvement, such as no caudate lobe resection, as independent predictors of poor survival (p < 0.05). Conclusions: In the current study, the newly released 8th edition of AJCC staging system showed no significant benefit compared to the previous 7th edition in predicting the prognosis of patients undergoing liver resection for perihilar cholangiocarcinoma. Further research may help to improve the prognostic value of the AJCC staging system for PHC—for instance, by identifying new prognostic markers or staging criteria, which may improve that individual patient’s outcome