Resistência ao impacto de revestimentos para fundições odontológicas, em diversas condições de temperatura no forno

The impact strenght of four dental casting investments is investigated as a function of heat loss after removal of tu a furnace temperature of 700ºC, at different time intervals. Attention is called to the fact hat a graphical relationship between temperature loss and lmpact strenght, even hough obtained from averages of 10 experiments, but without a statistical analysls, may induce to erroneous conclusions.

Warmed contrast media temperature loss in traditional manifold systems during angiographic procedures

Background Extrinsic warming of contrast media (CM) to 37 °C before angiographic procedures is performed to improve bolus kinetics and avoid potential adverse effects. Extrinsically warmed CM readily loses temperature after removal from the warming cabinet, but the extent of its cooling has not been previously investigated. Purpose To assess temperature loss of extrinsically warmed CM in tubing of traditional angiographic manifolds during simulated angiography. Material and Methods In total, 35 scheduled diagnostic angiographic procedures were observed in a hospital setting. Relevant time points of CM use during the procedures were recorded. The shortest, median, and longest procedures were then simulated in the experimental laboratory to measure CM temperatures at specific times at three locations along the tubing system. Results The angiographic procedures lasted 7.0–26.6 min (median = 11.7 min), with the total duration dependent primarily on the time from contrast being removed from the warming cabinet to the commencement of imaging. During the simulated procedures, consistent patterns of temperature loss were observed. By the last simulated angiographic run, injected CM temperature decreased by 7.4–16.4 °C, depending on procedure length. Most of the heat loss occurred in the tubing between the CM bottle and coronary control syringe. Conclusion During angiographic procedures, prewarmed CM loses its temperature rapidly with the duration of exposure to ambient room temperature. If no additional measures are employed to maintain its temperature outside of the warming cabinet, extrinsic warming has limited impact on injected CM temperature.

Physical Experiment and Numerical Simulation on Thermal Effect of Aerogel Material for Steel Ladle Insulation Layer

The selection of lining material for a steel ladle is important to heat preservation of molten steel. Aerogel insulation materials have very low thermal conductivity, however, they are rarely used in steel ladles. In this paper, the application of a new silica aerogel material on the steel ladle insulation layer is tested, and a new calculation method is designed to study its insulation effect. In other words, the ladle wall temperature is obtained by finite element model (FEM) and experiments, then the heat emission from the ladle wall is calculated by the Boltzmann mathematical model according to the ladle wall temperature, and the temperature loss of molten steel is calculated inversely according to the heat emission of ladle wall. Compared with the original steel ladle (comparison ladle), the application effect is analyzed. Due to the stable heat storage of the ladle wall after refining, the validity of the models are verified in ladle furnace (LF) process. The results show that the new calculation method is feasible, and the relevant parameter settings in the FEM and Boltzmann mathematical model are correct. Finally, after using the new aerogel insulation material, the temperature of molten steel is reduced by 16.67 °C, and the production cost is reduced by CNY 5.15/ton of steel.

Experimental Study on Effects of Adjustable Vaned Diffusers on Impeller Backside Cavity of Centrifugal Compressor in CAES

The impeller backside cavity (IBC) is a unique structure of centrifugal compressor in compressed air energy storage (CAES) systems, which affects the aerodynamic performance of centrifugal compressor, and the angle change of the downstream coupled adjustable vaned diffusers (AVDs) will affect the flow field inside the cavity and compressor performance. This paper relies on the closed test facility of the high-power intercooling compressor to measure static pressure and static temperature at different radii on the static wall of the IBC. The coupling relationship between the IBC and compressor under variable operating conditions is analyzed, and the influence of AVDs on the internal flow in IBC is studied. The results show that static pressure and static temperature rise along the direction of increasing radius, but static temperature drops near the coupling between the impeller outlet and the cavity inlet. Under AVDs’ design angle, static pressure and static temperature at each point, static pressure loss and static temperature loss in the direction of decreasing radius all increase as the flow decreases. Under variable AVDs’ angles, static pressure and static temperature will change differently, and respective loss will also be different.

P–250 Mineral oil with high viscosity improves the stability of pH and osmolality in the human in vitro culture system

Study question Do commercial mineral oil brands differ in their capacity to stabilize the human embryo culture system, and is this related to the oil’s viscosity? Summary answer While the oils’ viscosity only had minor effects on temperature maintenance, it showed a direct correlation with the stability of pH and osmolality during culture. What is known already Mineral oil is a key component of the in vitro embryo culture system, which stabilizes temperature, pH and osmolality of the media during culture. Its use has been implemented worldwide for several decades and many manufacturers currently produce and commercialize oil intended for human embryo culture. Unfortunately, oil remains as one of the less characterized products in the IVF laboratory due to a lack of standardized nomenclature, production and testing. With differing physico-chemical properties, such as viscosity, oils produced by various manufacturers could behave differently to the same culture conditions and, thus, its use may need to be adjusted accordingly. Study design, size, duration Viscosity was quantified in three high-viscosity (H-V) and three low-viscosity (L-V) oils with a viscosity-meter. The required time for media’s pH to equilibrate using each oil was studied, as well as its subsequent stability outside the incubator for 30min. In-drop temperature was assessed during 15min when taking a dish outside the incubator, and again when putting it back. Additionally, each oil’s capacity to avoid media evaporation was studied with daily osmolality measurements during 7 days. Participants/materials, setting, methods pH equilibration was measured with a continuous pHmeter (Log&Guard, Vitrolife) in 4-well dishes prepared with 600µl of medium and 500µl of oil. For the other experiments, 35mm dishes with 4ml of oil and 20µl media droplets were used. pH stability was assessed after 0, 15 and 30min outside the incubator with a blood-gas-analyzer (epoc,SiemensHelthineers). A fine-gauge thermocouple was used to measure in-drop temperature loss/recovery. Daily osmolality readings were taken with a vapor pressure osmometer (Vapro5600,Wescor). Main results and the role of chance The selected oil samples had a viscosity of 115, 111, 52, 22, 18, and 12cP. The medium’s pH took approximately 12h to completely equilibrate under H-V oils, while it took less than 4h in L-V. Similarly, the rise in pH after 30min on a heated stage outside of the incubator with room atmosphere was 0.03, 0.04, 0.06, 0.13, 0.17, and 0.26, respectively. Dishes were taken out of the incubator and placed on a heated surface. In the first five minutes, the in-drop temperature loss ranged between –0.22 and –0.13oC/min, with no significant differences observed between oil types. However, temperature plateaued at a significantly higher value in L-V oils (36.5oC), compared to H-V brands (36.25–36.1oC; p = 0.0005). By contrast, all samples followed a similar pattern when the dishes were returned to the benchtop incubator, with temperature taking around 7 minutes to completely recover. Some media evaporated in all oil groups during the 7-day culture in a dry benchtop incubator. The linear regression performed to compare the evaporation rate between groups showed a statistically significant correlation between oil viscosity and the rate of evaporation (p < 0.0001), with an osmolality rise ranging between +2.55mmol/kg/day in the most viscous oil and +6.29mmol/kg/day in the least viscous. Limitations, reasons for caution While the selected oils for this study represent a wide range of options in the market, future projects could widen this selection and include additional tests, such as optimized bioassays. Results may vary between centers, and thus each laboratory should test and optimize their culture system with their own settings. Wider implications of the findings: Different oil brands have shown differing physico-chemical properties that have a direct effect on the culture system and the stability of several culture conditions. These results may be of major importance to adapt the settings and methodologies followed in each IVF laboratory according to the type of oil being used. Trial registration number Not applicable

A Potential Approach for Paraffin Control for Wells in South West Trinidad Oilfields Using Wax Inhibitors and Paraffin Solvent

Paraffin deposition in production tubing and flow lines is a phenomenon that affects many oil producers. Once paraffin wax has precipitated there is a tendency to agglomerate peripherally to the production flow path which eventually leads to a sectional decrease in tubing or, even, flow blockage across production zones. The impact of paraffin deposition ranges from wellbore issues, flow assurance challenges to total production impairment. In many mature fields, paraffin remediation can be challenging when deposition occurs in the formation especially in near-wellbore regions of producing wells. Temperature loss at these locations induces wax crystallization and subsequent formation damage. A mitigative approach to paraffin deposition in these areas can typically include the utilization of both paraffin inhibitors and paraffin solvents individually or in combination. However, as it pertains to paraffin remediation downhole, inhibitor placement in the formation or at near-wellbore has proven to be very challenging. This paper reviews the performance of two main chemical applications applied to address downhole wax deposition in a well from a South West Trinidad oilfield. The paper also discusses the strategy behind identifying the chemical type for the application and considerations for the placement of the chemical treatment to impact its intended target based on well data and well infrastructure.

Dimensional accuracy in quick plastic forming of aluminum alloy using demolding mechanism

This study focuses on quick plastic forming (QPF), product dimensional tolerances, and removal methods. The traditional curled metal shell mold in QFP, has limitations such as long process time and unstable quality. Therefore, this investigation designed a demolding mechanism, in order to improve the process efficiency and dimensional accuracy of QPF, in the manufacture of metal casings. The research results show that the proposed mechanism can significantly decrease the process time, because it replaces most of the operations of specimens movement after forming completely. The shorter process time reduce the die temperature loss during operation, thus also improving the efficiency by eliminating the need to wait for the die to return to its operation temperature. In terms of dimensional tolerance, the tolerance grade of QPF process was determined using the standard deviation, and found to be between IT10 and IT14. This range covers the scope of CNC cutting and stamping processing, indicating that the process has commercial value in the production of metal casings, because the current mainstream manufacturing process of metal casings comprises casting, stamping and CNC machining.

Optimisation design of short pitch spiral hybrid SCR structure for improving the exhaust performance

As exhaust emission standards become increasingly stringent, the requirements for diesel exhaust post-treatment systems become increasingly demanding. This research focuses on the optimisation of a new hybrid structure to improve the performance of exhaust post-treatment systems. First, a short pitch spiral mixing chamber with sufficient mixing space and low temperature loss was designed to improve the evaporation of liquid droplets. Additionally, a conical plate mixer was used to conduct secondary mixing of the gas to improve the flow characteristics further. The ammonia uniformity and crystallisation risk of the new hybrid structure were simulated using Computational Fluid Dynamics, and the optimal hybrid structure was verified by tests. The results showed that ammonia leakage, low temperature crystallisation and NOX conversion efficiency could effectively be improved by optimally designing the new hybrid structure. This research is of great significance for reducing exhaust pollution and optimising diesel exhaust post-treatment systems.

The Effect of Sevoflurane Low Flow Anesthesia on Preserving Patient Core Temperature

Background: Low flow anesthesia reduces the fresh gas flow (FGF) entering the anesthesia circuit and saves on the volatile agent used. In this study, the effect of low-flow anesthesia with sevoflurane on core temperature and the incidence of perioperative hypothermia were investigated.Methods: Records of patients who underwent general anesthesia with sevoflurane were analyzed retrospectively. According to the fresh gas flow applied, the patients were divided into three groups: Low flow anesthesia (LFA = 1 l / min), medium flow anesthesia (MFA = 2 l / min), and high flow anesthesia (HFA = 4 l / min). Patients’ demographic data and the initial (T1) and final (T2) temperatures during the operation were compared.Results: A total of 160 patients were included in the study. There was no significant difference in T1 temperature values between the groups. The T2 value of the HFA group was significantly lower than the LFA group (p = 0.028). Different flow values were found to have a significant effect on temperature change (F = 21.630, p <0.001, partial eta squared = 0.216). There was a significant difference between the mean temperatures measured at two different times (F = 301.064, p <0.001, partial eta squared = 0.657). The overall incidence of hypothermia was 32.5%, with 52 patients. Hypothermia (T2<36 degrees) incidences were not different between the LFA group and the MFA and HFA groups (p = 0.682); However, perioperative core temperature loss was significantly lower in the LFA group (p = 0.001).Conclusions: Low flow anesthesia using sevoflurane was not sufficient alone to reduce the incidence of hypothermia. However, the LFA technique preserved the patient’s core temperature better than the MFA and HFA techniques. Therefore, in addition to low-flow anesthesia being a cost-oriented technique, we have demonstrated that it may also have a beneficial effect on reducing perioperative temperature loss.Trial Registration: Researchregistary.com/6840Ethics committee: Yozgat Bozok University 2017-KAEK-25122019.1