Fluid Supply and Feeding Practices in Cooled Asphyxiated Newborns

Therapeutic hypothermia (TH) for 72 h is the standard treatment to reduce neurological deficits in term newborns with hypoxic-ischemic encephalopathy. There is a large variability regarding nutritional supply during TH treatment in asphyxiated newborns. We performed a retrospective multicentre study in four level I (highest level of care in Germany) NICUs, including 135 asphyxiated term newborns undergoing TH. We analyzed enteral and parenteral nutritional supply during and after TH. We correlated nutritional supply with risk factors for encephalopathy, pH, Sarnat score, mechanical ventilation, seizures, and sedation. A total of 120 of 135 neonates received enteral nutritional supply within the first 24 h, and the majority of children were fully enterally fed within the first 10 days. The grade of encephalopathy and mechanical ventilation had a significant influence on the amount of enteral fluids (p = 0.01), whereas the pH and appearance of seizures did not affect the amount of nutritional supply significantly. Furthermore, we did not observe any correlation between enteral intake and abdominal complications such as necrotizing enterocolitis. We observed a large variability of feeding regimes in the four participating NICUs. Early enteral feeding among newborns undergoing TH was performed in each NICU and was well tolerated without increased rates of complications.

Mathematical Model for Rate Transient Analysis with Additional Interface Skin for Fractured Horizontal Well With Weak Fluid Supply

This paper develops a mathematical model for rate transient analysis in multi-stage fractured horizontal wells with considering weak fluid supply. A new concept of additional skin factor is introduced in the proposed model to characterize the fluid supply. Then, the mathematical model are solved by using the perturbation transformation, point source integration method, Laplace transform, and numerical inversion, while the fracture flow equations are solved by fracture discretization and superposition principle. First, the flow regimes of multi-stage fractured horizontal wells with considering weak fluid supply are identified based on the rate transient behaviors, including wellbore storage and skin effect, bilinear flow, linear flow, pseudo-radial flow in the fractured zone, interface skin effect, pseudo-radial flow in the original zone, and boundary-dominated flow. The effect of additional interface skin makes the double logarithmic curve of production rate appear an abrupt "overlap". The results of the sensitivity study show that the abrupt "overlap" becomes more obvious with the increase of the fracture conductivity, fracture number, the stress sensitivity coefficient, especially the interface skin. Finally, the proposed mathematical model is used to perform a case study on the production data of actual tight-gas wells from the Ordos Basin. The interface skin factor, fracture half-length, fracture conductivity, and boundary radius are evaluated. Through the proposed model, the characteristics of weak fluid supply in tight gas reservoirs are fully understood.

Influence of the frequency of pulsating high-pressure cutting fluid jets on the resulting chip length and surface finish

High-pressure cutting fluid supply is a proven technology for chip breaking when turning difficult-to-cut materials, such as Inconel 718. However, the technology is usually not suitable for the finish turning of safety-critical parts in aero engines. The acting force of the cutting fluid jet on the back of the chip causes chip breaking. The broken chips are then accelerated by the cutting fluid jet towards the workpiece surfaces where they cause damage on impact. One approach to minimize surface damage is a specific increase in the chip length. The center of gravity of the chips with an adjusted length is shifted out of the focus where the cutting fluid jet hits the chips. Hence, the already finished surface is subjected to fewer impacts of the chips. In this study, the adjustment of the chip length by pulsating high-pressure cutting fluid supply to prevent surface damage was investigated. A valve unit was used to generate two alternating cutting fluid supply pressure levels in certain time intervals. During the low-pressure stage, the force of the cutting fluid jet does not lead to chip breakage and the chip length increases until the valves switch and the high-pressure stage is released. The focus of this work was the analysis of the relationship between the duration of the low-pressure and high-pressure time intervals and the chip length. Additionally, the influence of the depth of cut, the feed, and the cutting speed on the chip length during pulsating high-pressure cutting fluid supply was investigated. Finally, a case study was carried out to evaluate the effectiveness of the pulsating high-pressure cutting fluid supply technology. Therefore, the shoulder surface of a demonstrator part was finished by face turning. Following, the cylindrical surface was finished with a continuous and pulsating high-pressure cutting fluid supply with varied supply parameters. Microscopic analyses of the surface prove that the pulsating high-pressure cutting fluid supply prevents the surface from being damaged by the impacts of chips.