RESUMO
Enhanced boiling heat transfer via surface engineering is a topic of general interest for its great demand in industrial fields. However, as a dynamic interfacial phenomenon, a deep understanding of its process and mechanism, including liquid re-wetting and vapor departure, is still challenging. Herein, a micro-/nanostructured Cu surface containing a periodic microgroove/pyramid array with rich nanowrinkles is designed, where superspreading (<134.1 ms) of organic cooling agents highly boosts the liquid re-wetting process, causing a discontinuous solid-liquid-vapor three-phase contact line and ultralow under-liquid bubble adhesion force (≈1.3 µN). Therefore, a characteristic, ultrafast jet-flow boiling (bubbles rapidly ejected in multiple strips) is obtained on this surface, giving a priority to nucleation (superheat ≈ 1.5 °C) and simultaneously enhancing the critical heat flux and heat-transfer coefficient by up to 80% and 608%, respectively, compared with a flat surface. In situ observation and analysis of the nucleation, growth, and departure of micro-sized jet-flow bubbles reflects that microgrooves/pyramids with nanowrinkles promote the latent heat exchange process by superspreading-induced ultrafast liquid re-wetting and constant vapor film coalescing. Based on the designed structures, high-performance phase-change cooling for central processing unit heat management in supercomputer centers is accomplished with an ultralow power usage effectiveness (PUE < 1.04).
RESUMO
OBJECTIVE: The purpose was to study the monitoring effect and application value of two-dimensional speckle tracking imaging (2D-STI) on myocardial function in patients with malignant lymphoma after treatment with anthracyclines. METHODS: 50 patients with malignant lymphoma treated in our hospital from June 2017 to December 2019 were randomly selected and were treated with anthracyclines to compare the cardiac global longitudinal strain (GLS), global radial strain (GRS), global circumferential strain (GCS), left ventricular twist (LVtw), GLS × LVtw, and changes of atrioventricular inner diameters before and after 3 cycles of treatment. According to the pathological examination results, the accuracy of 2D-STI in the detection of changes in myocardial function of patients was also clarified. RESULTS: The absolute values of GLS, GRS and GCS after treatment were significantly lower than those before treatment, with statistical significance (P < 0.05). The LVtw and GLS × LVtw after 3 cycles of treatment were significantly lower than those before treatment, with statistical significance (P < 0.05). There was no significant difference in the atrioventricular inner diameters of patients before and after treatment, with no statistical significance (P > 0.05). There was no significant difference between the monitoring results of 2D-STI and the pathological examination results, with no statistical significance (P > 0.05). CONCLUSION: Anthracyclines can cause some myocardial damage in patients with malignant lymphoma. The application of 2D-STI to monitor the changes in myocardial function of patients can give more accurate monitoring results, facilitating the early implementation of appropriate treatment.