Outcomes of palliative local treatment in metastatic colorectal cancer patients receiving chemotherapy plus bevacizumab

Objective The aim of this study was to assess the value of palliative local treatment of incurable metastatic lesions in colorectal cancer(CRC) patients receiving chemotherapy plus bevacizumab.Methods Data of 105 patients with histologically confirmed synchronous or metachronous metastatic CRC who received bevacizumab treatment from January 1, 2011 to January 31, 2017 were retrospectively reviewed. Sixteen(15%) patients who were treated with bevacizumab for less than 4 cycles were excluded, and finally, 89(85%) patients were enrolled. Among them, 33(37%) patients who received palliative local treatment were categorized into the palliative local treatment group, and the remaining 56(63%) patients were categorized into the chemotherapy plus bevacizumab group. The primary endpoint was overall survival(OS), which was calculated using Kaplan-Meier survival analyses. Factors possibly influencing survival were evaluated by univariate and multivariate analyses. Adverse events(AEs) were graded according to Common Terminology Criteria for Adverse Events, version 4.0. Grades 1–2 and 3–4 AEs of the two groups were compared and analyzed using the Fisher's exact test and χ~2 analysis.Results The median follow-up period was 20.4 months, ranging from 1 to 60 months. The median OS in the palliative local treatment group was 36.3 months(95% CI, 33.5–39.2), and that in the chemotherapy plus bevacizumab group was 20.5 months(95% CI, 17.6–23.4). Both the univariate(HR 0.13, 95% CI, 0.05–0.30, P < 0.001) and multivariate(HR 0.16, 95% CI, 0.07–0.39, P < 0.001) analyses showed that the addition of palliative local treatment could prolong survival compared with chemotherapy plus bevacizumab alone. There were no significant differences in the rates of common chemotherapy-or bevacizumab-related AEs between the two groups.Conclusion These findings suggest palliative local treatment is an effective and safe method for treating patients with incurable metastatic CRC receiving chemotherapy plus bevacizumab.

Experimental investigation of characteristics of instability evolution in a centrifugal compressor

The stable range of operation for the centrifugal compressor significantly influences the dynamic,economic,and environment-friendly characteristics of power systems.A deep understand-ing of the characteristics of instability evolution is necessary to improve the compressor stability.A centrifugal compressor equipped with a vaneless diffuser is experimentally investigated using high-response static-pressure measurements.The results obtained indicate that three typical rotational-speed ranges exist based on the different instability evolution characteristics,which reveals the var-ious impeller–diffuser matching behaviors over the entire speed range.At low-speed ranges((40%–75%)N_(max),N_(max)is the maximum rotational speed),the compressor exhibits stable,Rotating Insta-bility(RI),impeller stall(diffuser stall),and surge modes.The impeller stall mode is induced by RI and propagates downstream,resulting in the diffuser stall and compressor surge modes.In the medium-speed range((75%–85%)N_(max)),the compressor exhibits stable,diffuser stall,RI,and surge modes.In the high-speed range((85%–100%)N_(max)),the compressor exhibits stable,diffuser stall,and surge modes.The dominant instability position is shifted from the impeller to the diffuser as the rotational speed increases.Both the impeller and diffuser stall present an irregular sawtooth static-pressure wave and exhibit broadband frequency spectrum patterns.

Investigation on Centrifugal Impeller in an Axial-radial Combined Compressor with Inlet Distortion

Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment.Then upstream potential flow and wake effect appear at centrifugal impeller inlet.In this paper,the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor.The results show that spanwise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet.The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases.Circumferential distortion causes different separated flow formations at different pitch positions.The tip leakage vortex is suppressed in centrifugal blade passages.Under distorted inlet condition,flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span.In addition,compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.

Numerical analysis for impacts of nozzle end-clearances on aerodynamic performance and forced response in a VNT turbine

It has been well known that nozzle end-clearances in a Variable Nozzle Turbine（VNT）are unfavorable for aerodynamic performance, especially at small openings, and efforts to further decrease size of the clearances are very hard due to thermal expansion. In this paper, both the different sizes of nozzle end-clearances and the various ratios of their distribution at the hub and shroud sides were modelled and investigated by performing 3D Computational Fluid Dynamics（CFD） and Finite Element Analysis（FEA） simulations with a code of transferring the aerodynamic pressure from the CFD results to the FEA calculations. It was found that increasing the size of the nozzle end-clearances divided equally at the hub and shroud sides deteriorates turbine efficiency and turbine wheel reliability, yet increases turbine flow capacity. And, when the total nozzle endclearances remain the same, varying nozzle end-clearances＇ distribution at the hub and shroud sides not only shifts operation point of a VNT turbine, but also affects the turbine wheel vibration stress.Compared with nozzle hub clearance, the shroud clearance is more sensitive to both aerodynamic performance and reliability of a VNT turbine. Consequently, a possibility is put forward to improve VNT turbine efficiency meanwhile decrease vibration stress by optimizing nozzle end-clearances＇ distribution.