Research on Abrasive Water Jet Polishing of Silicon Carbide Based on Fluid Self-Excited Oscillation Pulse Characteristics.

A self-excited oscillating pulsed abrasive water jet polishing method is proposed to solve the problems of low removal efficiency in traditional abrasive water jet polishing and the influence of an external flow field on the material surface removal rate. The self-excited oscillating chamber of the nozzle was used to generate pulsed water jets to reduce the impact of the jet stagnation zone on material surface removal and increase the jet speed to improve processing efficiency. ANSYS Fluent was employed to simulate the processing flow field characteristics for different lengths of oscillation cavities. The simulation results indicate that the velocity of the jet shaft reached a maximum of 178.26 m/s when the length of the oscillation cavity was 4 mm. The erosion rate of the material is linear with the processing angle. A nozzle with a length of 4 mm of the self-excited oscillating cavity was fabricated for SiC surface polishing experiments. The results were compared with those of ordinary abrasive water jet polishing. The experimental results showed that the self-excited oscillation pulse fluid enhanced the erosion ability of the abrasive water jet on the SiC surface and significantly improved the material-removal depth of the abrasive water jet polishing SiC. The maximum surface erosion depth can be increased by 26 µm.

Significant Electromechanical Characteristic Enhancement of Coaxial Electrospinning Core-Shell Fibers.

Electrospinning is a low-cost and straightforward method for producing various types of polymers in micro/nanofiber form. Among the various types of polymers, electrospun piezoelectric polymers have many potential applications. In this study, a new type of functional microfiber composed of poly(γ-benzyl-α,L-glutamate) (PBLG) and poly(vinylidene fluoride) (PVDF) with significantly enhanced electromechanical properties has been reported. Recently reported electrospun PBLG fibers exhibit polarity along the axial direction, while electrospun PVDF fibers have the highest net dipole moment in the transverse direction. Hence, a combination of PBLG and PVDF as a core-shell structure has been investigated in the present work. On polarization under a high voltage, enhancement in the net dipole moment in each material and the intramolecular conformation was observed. The piezoelectric coefficient of the electrospun PBLG/PVDF core-shell fibers was measured to be up to 68 pC N-1 (d33), and the voltage generation under longitudinal extension was 400 mVpp (peak-to-peak) at a frequency of 60 Hz, which is better than that of the electrospun homopolymer fibers. Such new types of functional materials can be used in various applications, such as sensors, actuators, smart materials, implantable biosensors, biomedical engineering devices, and energy harvesting devices.

The CoCoS trial: Caloric Control in Cardiac Surgery patients promotes survival, an interventional trial with retrospective control.

BACKGROUND & AIMS: Malnutrition is widespread among cardiac surgery patients and is independently related to an adverse postoperative evolution or outcome. We aimed to assess whether nutrition therapy (NT) could alter caloric deficit, morbidity, and mortality in patients scheduled for non-emergency coronary artery bypass graft (CABG) or aortic valve surgery. METHODS: 351 patients undergoing either elective CABG or aortic valve surgery were studied. Patients receiving NT were enrolled from January 2013 until December 2014. A retrospective control group (CT) consisted of 142 matched patients. The primary endpoint was to evaluate whether NT could limit caloric deficit (Intake to Need Deviation). Secondary endpoints addressed the potential effect of NT on morbidity and mortality. Patients were followed for one year after surgery. RESULTS: There was no significant difference in patient, laboratory or mortality profile between the groups. Caloric deficit could be limited in the intervention group, essentially by providing oral feeding and oral supplements. A minority of patients required enteral or parenteral nutrition during their hospital stay. Caloric deficit increased after the second postoperative day because more patients were switched to oral feeding and intravenous infusions were omitted. Combining CABG and aortic valve surgery, male patients in the NT group had significantly less arrhythmia than in the CT group (7% versus 31%; P = 0.0056), while females in the NT group had significantly less pneumonia than in the CT group (7% versus 22%; P = 0.0183). Survival was significantly higher in female NT patients compared to CT patients, both for CABG (100% versus 83%; P = 0.0015) and aortic valve surgery (97% versus 78%; P = 0.0337). CONCLUSION: The results suggest that NT beneficially affects morbidity and mortality in elective cardiac surgery patients. The impact of NT seems more pronounced in women than in men. Registration: Clinicaltrials.gov: NCT02902341.