Optimization of Maturation of Radio-Cephalic Arteriovenous Fistula Using a Model Relating Energy Loss Rate and Vascular Geometric Parameters

The main reason for the early failure of radio-cephalic arteriovenous fistula (RCAVF) is non-maturity, which means that the blood flow rate in the fistula cannot increase to the expected value for dialysis. From a mechanical perspective, the vascular resistance at the artificially designed anastomosis causes an energy loss that affects blood flow rate growth and leads to early failure. This research studied how to maximize the RCAVF maturity and primary patency by controlling the energy loss rate. We theoretically analyzed and derived a model that evaluates the energy loss rate Eavf in RCAVF as a function of its blood vessel geometric parameters (GPs) for given flow rates. There was an aggregate of five controllable GPs in RCAVF: radial artery diameter (Dra), cephalic vein diameter (Dcv), blood vessel distance between artery and vein (h), anastomotic diameter (Da), and anastomotic angle (θ). Through this analysis, it was found that Eavf was inversely proportional to Dra, Dcv, Da, and θ, whereas proportional to h. Therefore, we recommended surgeons choose the vessels with large diameters, close distance, and increase the diameter and angle of the anastomosis to decrease the early failure of RCAVF. Simultaneously, we could explain the results of many clinical empiricisms with our formula. We found that increasing Dcv and θ was more significant in reducing Eavf than increasing Dra and Da. Based on our model, we could define two critical energy loss rates (CELa, CELb) to help surgeons evaluate the blood vessels and choose the ideal range of θ, and help them design the preoperative RCAVF plan for each patient to increase the maturity and the primary patency of RCAVF.

Replication of large area nanoimprint stamp with small critical dimension loss

In this paper,the replication process of large area nanoimprint stamp with small critical dimension(CD) loss was investigated,using the thin residual layer nanoimprint lithography(NIL) technology.The residual layer thickness was optimized by changing the spin-coated resist thickness.The dependences of the residual layer etching rate on gas flow,chamber pressure,and RF power were investigated,and the optimized process conditions were established.By means of the thin residual layer NIL technique and optimized residual layer etching process,large area stamp with small CD loss and multi-orientation patterns was successfully replicated on 2-inch SiO2/Si wafer.The CD loss was controlled within 5 nm.The replicated stamp showed high performance in the patterning with thermal NIL.The replication process reported in this work could also be used to fabricate large area nanostructures with small CD loss.

Impact of overweightness and critical weight loss on overall survival in patients with hepatocellular carcinoma initially treated with chemoembolization

Background:The effects of overweightness and weight loss on the development and prognosis of hepatocellular carcinoma(HCC)remain unclear.In this study,we aimed to evaluate the impact of overweightness and weight loss on the survival of patients with intermediate/advanced HCC receiving chemoembolization as initial treatment.Methods:We examined 1,170 patients who underwent chemoembolization as initial treatment for Barcelona-Clı´nic Liver Cancer stages B and C HCC at Sun Yat-sen University Cancer Center(Guangzhou,China)between December 2009 and May 2015.A baseline body mass index(BMI)of23 kg/m2 was defined as overweight,and body-weight loss of5.0%from baseline was defined as critical weight loss(CWL).Cox regression analysis was used to determine the association between overweightness or CWL and overall survival(OS).Results:The median survival time was 16.8(95%confidence interval,13.9–19.7)months and 11.1(95%confidence interval,10.0–12.2)months in the overweight and non-overweight groups(log-rank test,P<0.001),respectively.Cox multivariate analysis identified overweightness as an independent protective prognostic factor for OS(P<0.001).Subgroup stratification analysis revealed a significant association between overweightness and survival among patients receiving further treatment(P=0.005),but not in those not receiving further treatment(P=0.683).Multivariate analysis showed that both overweightness and CWL were independent prognostic factors for OS among patients receiving further treatment.Conclusion:Among patients with intermediate-or advanced-stage HCC initially treated with chemoembolization,overweightness was associated with longer OS.Furthermore,CWL was an independent adverse prognostic factor for OS in patients receiving additional treatment.