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The entire compression system of DGEN380 was selected to study the degradation of aerodynamic characteristics caused by erosion of the leading edge. Numerical simulations under different degrees of leading edge erosion were performed. It was found that the leading edge erosion causes a significant decrease in operability from 70 % of the blade height to the tip, and mainly affects the subsequent flow field in the bypass. At 90 % of blade height, the isentropic efficiency and total pressure ratio of the blade with leading edge erosion are reduced compared to the origin blade. Afterwards, the thrust equation was introduced to analyze the effect of leading edge erosion on the thrust loss under different operating conditions of the aircraft. Among the three operating conditions, the thrust loss rate of the cruise condition was the largest, which provided a reference for the subsequent evaluation of the blade repair condition.

Background: Klebsiella pneumoniae is one of the main pathogens of lower respiratory tract infections. Carbapenems are considered the last line of defense for the treatment of Gram-negative bacteria with multidrug resistance. In recent years, with the increase of bacteria producing carbapenemase, the resistance rate of carbapenems has increased gradually. Objectives: The main objective of this study was to detect the blaKPC and blaVIM genes in K. pneumoniae isolates from blood culture specimens. Methods: Within September 2020 to August 2022, 1033 bacterial strains were isolated from blood cultures in Yijishan Hospital of Wannan Medical College, Wuhu, Anhui province, China, including 141 strains of K. pneumoniae. All K. pneumoniae strains were processed for antimicrobial susceptibility testing (AST) using the minimum inhibitory concentration method. Meanwhile, the isolates were phenotypically identified for carbapenemase production by the colloidal gold method. Finally, the confirmed carbapenem enzyme phenotype was further verified for the production of blaKPC and blaVIM by polymerase chain reaction (PCR). Results: Regarding the rate of isolated strains in blood culture, positivity was 11.16% (1033/9255), and the proportion of K. pneumoniae was 13.65% (141/1033). Overall, according to AST results, 7.80% (11/141) of the isolates demonstrated resistance to carbapenems, such as ertapenem, imipenem, and meropenem; nevertheless, they showed sensitivity to colistin and ceftazidime/avibactam. Colloidal gold phenotypically confirmed 81.82% (9/11) of the isolates as carbapenemase producers. Subsequently, nine isolates’ strains were verified to be positive for blaKPC and blaVIM by PCR; the proportions of the blaKPC and blaVIM genes were 88.89% (8/9) and 11.11% (1/9), respectively. Conclusions: The identification of carbapenemase phenotype and genotype is helpful for the accurate understanding of drug resistance and management of the disease.

Objective Hemodynamic factors are thought to play important roles in the pathogenesis, progression, and rupture of cerebral aneurysms. Previous hemodynamic studies have been based on comparisons between post-ruptured and unruptured aneurysms. Nevertheless, changes of aneurysm morphology after rupture render these results unreliable. Moreover, pressure, age, gender, and the morphology of the parent artery also influence these results. Therefore, in the present study, we identified hemodynamic and morphological characteristics of aneurysms prior to rupture using twelve mirror aneurysms. Materials and methods From our database, we retrospectively analyzed twelve mirror aneurysms (MANs) prior to rupture. Each mirror aneurysm was divided into the prior to rupture or the unruptured group. Patient-specific models were reconstructed from three-dimensional (3D) images of all patients. Hemodynamic and morphological factors were analyzed and compared. Results Compared with the unruptured side of MANs, aneurysms prior to rupture were significantly larger and significantly more irregular in shape; they also had significantly higher aspect ratio (AR), size ratio (SR), undulation index (UI), ellipticity index (EI), percentage of low wall shear stress area (LSA) and significantly lower normal wall shear stress (NWSS). The oscillatory shear index (OSI) and nonsphericity index (NSI) in the aneurysms prior to rupture were non-significantly higher than those of the unruptured group. Conclusion MANs prior to rupture may be extremely useful models to assess the risk of aneurysm rupture. Larger size, irregular shape, higher AR, SR, UI, NI, and lower WSS may be associated with aneurysms at risk for rupture.

Biofilm formation is a major factor in the resistance mechanism of Klebsiella pneumoniae. This study aimed to evaluate the effects of sodium hypochlorite on the biofilm of K. pneumoniae with different drug resistance.We collected 3 different types of K. pneumoniae respectively. The growth trend of biofilms of different drug-resistant K. pneumoniae was quantified by measuring the ODAfter adding sodium hypochlorite, there were significant differences between the ODSodium hypochlorite inhibited and cleared the biofilm of K. pneumoniae with different drug resistance, and the effect was enhanced with the increase of concentration in the range of bacteriostatic and bactericidal concentration.

Objective: Morphological and hemodynamic parameters might predict rupture of intracranial aneurysms (IAs). A practical model for the study is patients with ruptured mirror IAs in which one is ruptured and the other is unruptured. Although there have been analyses of the morphology and hemodynamics of ruptured mirror posterior communicating artery aneurysms (PComAAs), the sample sizes in these studies were small and only considered hemodynamics or morphological characters. Therefore, this study aimed to investigate the morphological and hemodynamic parameters associated with ruptured mirror PComAAs.Methods: We considered 72 patients with ruptured mirror PComAAs using computational fluid dynamics (CFDs). Ruptured mirror PComAAs were divided into ruptured and unruptured groups. Fourteen morphological and eight hemodynamic parameters were calculated and compared. Significant parameters were analyzed by the multivariate logistic regression to identify independent risk factors. Receiver operating characteristic (ROC) analysis was performed, and the area under the ROC curve (AUC) was calculated for all independent risk factors to determine the predictability and identify the optimal threshold.Results: Four hemodynamic and three morphological parameters were significantly different between ruptured and unruptured groups: normalized wall shear stress (NWSS), mean WSS, low wall shear WSS area (LSA%), size, aspect ratio (AR), size ratio (SR), and inflow angle (IA). Multivariate logistic regression analysis showed that AR, SR, NWSS, mean WSS, and LSA% were all independent factors significantly associated with PComAAs rupture. The ROC analysis for independent risk factors indicated that AR (0.751), NWSS (0.755), mean WSS (0.69), and LSA (0.778) had merely acceptable AUC values. Only SR (0.803) had a high acceptable AUC value. The threshold value of SR was 1.96.Conclusions: SR (>1.96) was the most significant parameter associated with IA rupture, whereas AR, NWSS, mean WSS, and LSA independently characterized the status of IA rupture.

Jinlong Yuan,1,&ast; Chenlei Huang,2,&ast; Zhenbao Li,1 Xiaochun Jiang,1 Xintong Zhao,1 Niansheng Lai,1 Dayong Xia,1 Degang Wu,1 Bingbing Zhang,1 Xuanzhi Wang,3 Xinggen Fang1 1Department of Neurosurgery, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, People’s Republic of China; 2Department of Clinical Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, People’s Republic of China; 3Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xinggen FangDepartment of Neurosurgery, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Zheshan West Road 2, Wuhu, 241001, People’s Republic of ChinaEmail 18805536056@163.comObjective: Hemodynamic parameters are associated with the recurrence of intracranial aneurysms (IAs). Studies showed that high velocity and wall shear stress (WSS) were associated with IAs recurrence after endovascular treatment; nevertheless, factors such as small sample size, locations of IAs, and types of IAs (ie, sidewall or bifurcation) were neglected. The purpose of this study was to identify the hemodynamic characteristics associated with recurrence of middle cerebral artery bifurcation aneurysms (MCABAs) after total embolization by the method of computer fluid dynamics (CFD).Methods: Following inclusion criteria, we included 92 MCABAs treated with coils only after total embolization from January 2014 to January 2019. We segmented into recurrent and non-recurrent groups according to follow-up digital subtraction angiography (DSA). The MCABA models, including pre-operatively and immediate post-operatively, were reconstructed using 3D-DSAs. The hemodynamic parameters pre-operatively and immediately post-operatively between the groups were calculated and analyzed.Results: There were no significant differences between the recurrent and non-recurrent groups for spatially averaged wall shear stress (SAWSS), maximum wall shear stress (MWSS), velocity, or oscillatory shear index (OSI) at the neck pre-operatively. In the recurrent group, the WSS (22.02± 5.11 vs 37.43± 8.27 pa, p < 0.001), MWSS (42.59± 17.02 vs 66.98± 18.61 pa, p=0.014), velocity (0.86± 0.19 vs 1.44± 0.61 m/s, p=0.01) preoperatively were significantly higher than postoperative values. By contrast, in the non-recurrent group, the WSS (26.53± 8.18 vs 22.29± 8.64pa, p=0.002), MWSS (42.71± 14.01 vs 37.15± 15.56 pa, p=0.013), velocity (1.08± 0.43 vs 0.23 (0.52, 0.57) m/s, p < 0.001) postoperatively were significantly lower than preoperative values. The OSI, whether in the recurrent group or the non-recurrent group, did not differ significantly between groups (p=0.79 and p=0.19).Conclusion: Higher WSS (SAWSS, MWSS) and flow velocity at the aneurysm neck after embolization might be related to recurrence of bifurcation IAs. These might be applied to clinical post-embolization management for the evaluation of bifurcation IAs recanalization.Keywords: computational fluid dynamic, hemodynamics, middle cerebral artery bifurcation aneurysms, recurrence

Objective: Posterior communicating artery bifurcation aneurysms (PcomA-BAs) and infundibular dilations (PcomA-IDs) are found at the junction between the internal carotid artery (ICA) and the posterior communicating artery (PcomA). Several studies found that PcomA-IDs potentially progress to aneurysms and can even rupture. In our clinical practice, digital subtraction angiography (DSA) helps differentiate PcomA-IDs from unruptured PcomA-BAs. However, when PcomA-IDs are >3 mm in diameter or PcomA are absent on DSA, it is challenging to use DSA to differentiate PcomA-IDs from unruptured PcomA-BAs. Hemodynamic and morphological factors are thought to play important roles in the pathogenesis, progression, and rupture of cerebral aneurysms. We compared hemodynamic and morphological differences in unruptured PcomA-BAs and PcomA-IDs to better manage PcomA-IDs.Methods: We included 83 PcomA-IDs and 115 unruptured PcomA-BAs dignosed and measured using DSA from January 2015 to January 2019. Computational fluid dynamics was performed on these patient-specific models reconstructed using axial slices in DICOM format. Clinical, hemodynamic, and morphological factors were compared between the PcomA-IDs and PcomA-BAs. Significant parameters were analyzed using binary logistic regression analysis to identify independent risk factors. Receiver operating characteristic (ROC) analysis was performed on the independent risk factors to acquire cutoff values.Results: One hemodynamic and four morphyological parameters were significantly different between PcomA-IDs and PcomA-BAs: normalized wall shear stress (NWSS), size, the angle between the ophthalmic segment of the ICA and the PcomA (APcomA), the angle between the ophthalmic and the communicating segment of the ICA (AICA) and the diameter of the PcomA (DPcomA). Binary logistic regression analysis showed that small size and DPcomA as well as APcomA were all independent significant factors characterizing the status of PcomA-IDs and the ROC analysis for independent risk factors indicated the cutoff values of size, APcomA, and DPcomA were 3.45 mm, 66.27°, and 1.24 mm, respectively.Conclusions: Size, DpcomA, and ApcomA could independently characterize the status of PcomA-IDs. These might help us better differentiate them from real aneurysms and guide its management.

The development of high accuracy rifle has uncovered a need for understanding the movement of the bullet in muzzle flow. Recent researches have always been focused on computational fluid dynamics (CFD) and experimental research on the muzzle flow, which released many data, such as velocity and base pressure drop of projectile. Due to CFD tests are timeconsuming, a dynamic model for spatial motion of projectile is established. In this model an empirical relationship is utilized for the base pressure of projectile, and the model is assumed that the base pressure is along the axis of barrel which applied on the tail cone of the bullet; The spatial motion equations deduced from the mass center motion equations and Euler equations of motion are solved with Runge-Kutta method. A 7.62 caliber bullet is tested to verify the dynamic model. The result agrees with the CFD and experimental data, which shows that the model is applicable in predicting the translational motions, besides the angular motion of projectile is also presented, which can be the initial condition of exterior ballistics to analyses the firing accuracy.

Nitrogen source is one of the important factors that affect the microalgae growth and lipid accumulation. We studied the effects of various nitrogen sources (i.e. NaNO3, CO(NH2)2, NH4Cl and CH3COONH4) and amount on the growth density, lipid yield, and eicosapentaenoic acid (EPA) content of Nannochloropsis oculata by single factor experimental method. The results show that N. oculata preferred NH4+ as nitrogen source rather than NO3- and CO(NH2)2. NH4+ could promote the growth and lipid accumulation of N. oculata. With the increase of nitrogen concentration, the biomass and the content of polyunsaturated fatty acid (PUFA) increased, but the content of lipid decreased. CH3COONH4 was the most suitable for growth, accumulation of lipid and EPA of N. oculata among the four investigated nitrogen sources. The optimal concentration was 5.29 mmol/L.