Screening of DNA Barcode of Quarantine Phytophthora

Phytophthora is genus of plant-damaging Oomycetes, whose member species are capable of causing enormous economic losses on crops worldwide. In the present study, four candidate genes ITS, CO1, EF-1α and β-tubulin were tested using 123 strains of 80 species of Phytophthora to investigate the feasibility of ser- ving as DNA barcoding markers. The results showed that among the four candidate genes, ITS and CO1 had the highest success rate of PCR amplification and se- quencing, up to 100% and 96.7%. There were obvious barcode gaps in ITS, CO1 andβ-tubulin, but their frequency distributions of intra- and interspecific genetic distances were slightly overlapped. Wilcoxon rank sum test on intraspecific genetic distances of the four genes showed ITS = CO1 = β - tubulin = EF-1α indicating they bad the same effect on intraspecific discrimination, while the test on interspecific genetic distances of the four genes showed ITS 〉 C01 〉 β- tubulin 〉 EF - 1α. In summary, ITS and COl should be used in combination as the primary barcodes, β-tubulin as the complementary barcede for the identification of 11 quaran- tine Phytophthora species.

The Effect of Prostate Volume on Robotic-assisted Radical Prostatectomy

Objective:To investigate the effect of prostate volume on robot-assisted radical prostatectomy.Methods:Clinical data of 75 patients underwent RARP in the Affiliated Hospital of Qingdao University were retrospectively analyzed.The patients were divided into 3 groups according to size of prostate.A total of 35 cases with prostate volume less than 30ml were recorded as group 1,27 cases with volume of 30 to 50 ml were recorded as group 2,and 13 cases with volume greater than 50ml were recorded as group 3.Age,BMI,preoperative PSA,operation time,intraoperative bleeding volume,postoperative drainage volume,indwelling time of catheter,indwelling time of drainage tube,total hospitalization time,pathological stage,surgical margin,urine control and biochemical recurrence were observed.Results:All operations were performed under Da Vinci robot assistance,and no patient was transferred to open surgery.There was no significant difference in age,preoperative PSA,BMI,operation time,intraoperative bleeding volume,postoperative drainage volume,indwelling time of catheter,total hospitalization time,pathological stage,rate of positive surgical margin and recovery of urinary continence between the groups.Indwelling time of drainage tube was longer in group with larger prostate,6.4(±4.5)days in group 1,6.3(±2.9)days in group 2 and 7.1(±2.5)days in group 3.Gleason score was lower in group with larger prostate,with statistical difference.Conclusion:Prostate volume had no significant effect on urinary control,rate of positive surgical margin and recurrence after RARP.Gleason score of pathological tissue was lower and indwelling time of drainage tube was longer in patients with larger prostate after RARP.Operation time and intraoperative bleeding volume of large prostate patients underwent RARP need to be further studied.RARP has certain advantages for patients with large prostate.

Multi-objective optimization of frequency and damping of vertical stabilizer skin structure placed with variable-angle tows

The vibration characteristics of composite vertical stabilizer skin structures play a critical role in damping effects designed for overcoming the air disturbances experienced by aircraft structural components during flight.The first-order fundamental frequencies and their corresponding damping characteristics of the vertical stabilizer skin structure tow-steered by automatic fiber placement technique were optimized with the parameterized trajectories and plies as design variables.Firstly,the vibration and damping numerical models were derived based on Kirchhoff laminate theory,the Rayleigh-Ritz method,and the Strain Energy Method.Then the optimization model was developed by adopting the self-adaptive Differential Evolution Multi-objective optimization algorithm and incorporating the solution method of Pareto Front.The constraints of this optimization model considered the experimentally obtained minimum turning radius of prepregs tow-steered in automatic fiber placement process obtained from experimental tests.Finally,the comparison of numerical simulation results was conducted for the optimized trajectories and the conventional straight trajectories under various boundary conditions,and the numerical results were partially validated through damping and frequency tests.The results indicate the vibration characteristics of the composite vertical stabilizer skin structure can be enhanced to a large extent by optimizing fiber trajectories,and the enhancement percentage is affected by the boundary conditions of the actual structure.

Multi-objective optimization of different dome reinforcement methods for composite cases

A multi-objective optimization method was proposed for different dome reinforcement methods of a filament-wound solid rocket motor composite case based on a Radial Basis Function(RBF)model.Progressive damage of the composite case was considered in a simulation based on Hashin failure criteria,and simulation results were validated by hydraulic burst tests to precisely predict the failure mode,failure position,and burst pressure.An RBF surrogate model was estab-lished and evaluated by Relative Average Absolute Error(RAAE),Relative Maximum Absolute Error(RMAE),Root Mean Squared Error(RMSE),and R^(2)methods to improve the optimization efficient of dome reinforcement.In addition,the Non-dominated Sorting Genetic Algorithm(NSGA-II)was employed to establish multi-objective optimization models of variable-angle and variable-polar-radius dome reinforcements to investigate the coupling effect of the reinforcement angle,reinforcement layers,and reinforcement range on the case performance.Optimal reinforce-ment parameters were obtained and used to establish a progressive damage model of the composite case with dome reinforcement.In accordance with progressive damage analysis,the burst pressure and performance factor were obtained.Results illustrated that variable-angle dome reinforcement was the optimal reinforcement method compared with variable-polar-radius dome reinforcement as it could not only ensure the reinforcement angle’s continuous changing but also decrease the mass of composite materials.Compared with the unreinforced case,the reinforced case exhibited an increase in the burst pressure and performance factor of 36.1%and 23.5%,respectively.

Influence and optimization of parameters of prepreg viscosity during placement

This paper tested the viscosity of prepreg in the automatic placement process, and conducted the probe and placement-90° peel tests through the test systems. The law of variation of prepreg viscosity during the laying process was studied through these tests under different conditions by taking the peel force to intuitively and quantitatively characterise the viscosity of the prepreg.The results show that this viscosity is inversely proportional to the laying rate, proportional to the laying pressure, and quadratic to the laying temperature. Then, peel tests were simulated to validate both the correctness of the peel test and that of the probe test data fitting the two-line cohesion model. On this basis, a response surface test for laying and peeling was designed. Taking viscous peel force as the response target, the laying process parameters were optimised and the significance of their influence was further studied. The error between the test value and the predicted value of the maximum viscous peel force is 3.03%.

Enhancing VGI application semantics by accounting for spatial bias

Volunteered geographic information(VGI)is becoming an important source of geospatial big data that support many applications.The application semantics of VGI,i.e.how well VGI reflects the real-world geographic phenomena of interest to the application,is essential for any VGI applications.VGI observations often are spatially biased(e.g.spatially clustered).Spatial bias poses challenges on VGI application semantics because it may impede the quality of inferences made from VGI.Using species distribution modeling(SDM)as an example application,this article argues that spatial bias impedes VGI application semantics,as gauged by SDM model performance,and accounting for bias enhances application semantics.VGI observations from eBird were used in a case study for modeling the distribution of the American Robin(Turdus migratorius)in U.S.T.migratorius observations from the North American Breeding Bird Survey were used as independent validation data for model performance evaluation.A grid-based strategy was adopted to filter eBird species observations to reduce spatial bias.Evaluations show that spatial bias in species observations degrades SDM model performance and filtering species observations improves model performance.This study demonstrates that VGI application semantics can be enhanced by accounting for the spatial bias in VGI observations.