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  • Author: Songtao Wang x
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Abstract

Objective

To evaluate the efficacy and safety of robot-assisted laparoscopic radical prostatectomy (RALP) and laparoscopic radical prostatectomy (LRP) for the treatment of localized prostate cancer.

Methods

Meta-analysis was applied using Review Manager V5.3 software and the retrieved clinical trials comparing RALP with LRP for the treatment of localized prostate cancer published from 2000 to 2018 in PubMed, Ovid, ScienceDirect, and EMBASE datasets were analyzed.

Results

This meta-analysis included 16 articles, totaling 7952 patients, with 5170 RALP patients and 2782 LRP patients. Meta-analysis showed that RALP postoperative complications were fewer (P=0.0007), and the postoperative urinary continence rate was better at 1 year after surgery (P<0.00001). There was no statistical significance between RALP and LRP with regards to the positive incidence of surgical margin (P = 0.18).

Conclusion

As an emerging technology, RALP is superior to LRP for localized prostate cancer treatment in terms of postoperative complications, and postoperative urinary continence rate.

Abstract

Experimental research has been carried out at low speed to investigate the effect of additional leading-edge surface roughness on a highly-loaded axial compressor cascade. A 5-hole aerodynamic probe has been traversed across one pitch to obtain the distribution of total pressure loss coefficient, secondary flow vector, flow angles and other aerodynamic parameters at the exit section. Meanwhile, ink-trace flow visualization has been used to measure the flow fields on the walls of cascades and a detailed topology structure of the flow on the walls has been obtained. Aerodynamic parameters and flow characteristics are compared by arranging different levels of roughness on various parts of the leading edge. The results show that adding surface roughness at the leading edge and on the suction side obviously influences cascade performance. Aggravated 3-D flow separation significantly increases the loss in cascades, and the loss increases till 60% when the level of emery paper is 80 mm. Even there is the potential to improve cascade performance in local area of cascade passage. The influence of the length of surface roughness on cascade performance is not always adverse, and which depends on the position of surface roughness.

Abstract

Experiment and numerical simulation of flow transition in a compressor cascade with positively curved blade is carried out in a low speed. In the experimental investigation, the outlet aerodynamic parameters are measured using a five-hole aerodynamic probe, and an ink-trace flow visualization is applied to the cascade surface. The effects of transition flow on the boundary layer development, three-dimensional flow separation and aerodynamic performance are studied. The feasibility of a commercial computational fluid dynamic code is validated and the numerical results show a good agreement with experimental data. The blade-positive curving intensifies the radial force from the endwalls to the mid-span near the suction surface, which leads to the smaller scope of the intermittent region, the lesser extents of turbulence intensity and the shorter radial height of the separation bubble near the endwalls, but has little influence on the flow near the mid-span. The large passage vortex is divided into two smaller shedding vortexes under the impact of the radial pressure gradient due to the positively curved blade. The new concentrated shedding vortex results in an increase in the turbulence intensity and secondary flow loss of the corresponding region.

Abstract

Photocatalytic activity by supported TiO2 doping with Graphene oxide and Lanthanum were investigated. The carrier of cenosphere was prepared by using washing, acid-processing and alkali-processing, SEM result shows that the surface of cenosphere is glossy and smooth. Through photocatalytic degradation of methylene blue solution, photocatalytic activities of powder materials after treatment and the influencing factors were compared. The degradation rate of methylene blue by using 0.5% Lanthanum doped TiO2 is better than the other doping amounts. 0.5% GO doped TiO2 has the same rule. 0.5% La and 0.5% GO doping TiO2 were chosen as the optimum condition. SEM and XRD result shows the sol become antase-TiO2 and were coated uniformly in the surface of the carrier. The decoloration rate of the supporter material is about 90% in 60 minutes and it can maintain a very good photocatalytic performance after recycle 20 times. It indicates that the material has a wide application prospect.

Abstract

The bleeding air flow increases so as to meet the demand of higher efficiency and better performance of compressor, and the issues brought by the bleeding system is of great interest for more and more researchers. In the opened literature, most of the works were performed through single-passage calculations. However, the non-uniformity caused by the bleeding system lead to an undesirable effect on the compressor, thus the multi-passage calculations should taken into consideration. In the present study, the annulus cascade and bleeding system were numerical studied on ANSYS CFX to investigate the effect of the circumferential position of the bleeding duct holes on the non-uniformity in the compressor and to make it clear that how the non-uniformity is formed. Finally, it is found that the unequal air bleeding mass flow rate in different passages result in the non-uniformity in the compressor. The non-uniformity in circumferential position could be alleviated when the duct hole moving toward the suction surface, however, when the duct hole moving toward the pressure surface, the flow separation would be suppressed in more blade passages.

Abstract

A new geometry parametric method of winglet-cavity tip has been introduced in the optimization procedure based on three-dimensional steady CFD numerical calculation and analysis. Firstly, the reliability of numerical method and grid independency are studied. Then an aerodynamic optimization is performed in an unshrouded axial high pressure turbine with winglet-cavity tip. The optimum winglet-cavity tip has higher turbine stage efficiency and smaller tip leakage mass flow rate than the cavity tip and flat tip. Compared with the results of cavity tip, the effects of the optimum winglet-cavity tip indicate that the stage efficiency is improved effectively by 0.41% with less reduction of tip leakage mass flow rate. The variation of turbine stage efficiency with tip gap states that the optimum winglet-cavity tip obtains the smallest efficiency change rate ∆η/(∆τ/H). For the optimum winglet-cavity tip, the endwall flow and blade tip leakage flow pattern are used to analysis the physical mechanical of losses. In addition, the effects of pressure-side winglet and suction-side winglet are analyzed respectively by the deformation of the optimum winglet-cavity tip. The numerical results show that the pressure-side winglet reduces the tip leakage flow effectively, and the suction-side winglet shows a great improvement on the turbine stage efficiency.

Abstract

The effects of fouling on the performance of an axial compressor rotor were investigated numerically. The NASA Rotor 37 was considered to perform a numerical investigation by means of a commercial computational fluid dynamic code. The numerical model was validated by comparing with the experimental data available from literatures. The computed performance maps and exit parameter distributions showed a good agreement with experimental data. The model was then used to simulate the effect of fouling on compressor rotor by various fouling configurations including added thickness and surface roughness levels. The mechanism of the compressor deterioration due to fouling was discussed in detail. As a result, fouling causes a significant reduction in rotor total pressure ratio and isentropic efficiency. Increased roughness was found to have a greater influence on the rotor characteristic parameters than increased blade thickness. Increased wall roughness has a weaker influence on the operation range at stable conditions than that of increased blade thickness. Increasing the blade thickness significantly reduces the operation range of the rotor at stable conditions and has a stronger influence on the stable operation of the compressor. The interaction of shock wave/boundary layer was one of the main factors that influenced the rotor characteristics.

Abstract

Unsteady pulsed suction (UPS) was applied as an unsteady flow control (UFC) technique in a certain highly loaded compressor cascade to control the flow separations. Only two bleed holes symmetrically mounted on the endwalls (one on the upper endwall and another on the lower endwall) were set up to achieve steady constant suction (SCS) and UPS. The improvements in aerodynamic performance by SCS and UPS under different time-averaged suction flow rates are firstly investigated and compared. The related unsteady aerodynamic parameters of UPS such as excitation frequency, excitation location, pitch angle, and skew angle are discussed and analyzed in detail. The results show that UPS can provide a better flow control effect than SCS with the same time-averaged dimensionless suction flow rate in the control of flow separation. The aerodynamic performance of compressor cascades can be significantly enhanced by UPS when unsteady aerodynamic parameters are in their optimum ranges. Based on the optimum parameters for UPS, the total pressure loss coefficient is reduced by 19 % only with the time-averaged dimensionless suction flow rate ms=0.4 %.

Abstract

Objective

To investigate the relationship between uric acid and metabolic syndrome (MetS) in elderly women.

Methods

A total of 468 women aged ≥60 years participating in a health examination were enrolled. The association between uric acid and MetS and its individual variables was evaluated by univariate and multivariate logistic regression models.

Results

A dose-response relationship was observed for the prevalence of MetS and uric acid quartiles. Subjects in the second, third and fourth quartile of uric acid had a 2.23-fold, 2.25-fold and 4.41-fold increased risk, respectively, of MetS than those in the first uric acid quartile (p for trend <0.001). Furthermore, each 1 mg/dl increment of serum uric acid level had a 1.38-fold increased risk of MetS (OR 1.38; 95% CI, 1.14-1.69; p=0.001).

Conclusions

Our present study demonstrated that elevated uric acid was positively associated with the prevalence of MetS in elderly women. Further random control trials are needed to elucidate the effectiveness of treatment of hyperuricaemia in reducing the incidence of MetS in elderly women.