Search

Abrasive water jet is a highly efficient cutting technology. Through some sandstone cutting tests, the research on the optimal impact angle and inclined cutting mechanism of rock-like materials is carried out. Based on the macroscopic and microscopic observation of the cut’s inner wall, crystal glass cutting experiments are conducted to investigate the cutting motion process of abrasive water jet under different impact angles, revealing the variation laws of cutting depth, the characteristics of the cut’s inner wall, the trajectory of abrasive particles and the type of crystal destruction under different cutting pressures and impact angles. The test results show that the average cutting depth gradually increases with the increase of cutting pressure, while changing the impact angle can significantly change the jet’s cutting ability, and the best cutting effect is obtained at an impact angle of 75°. With the increase of the cut depth, the curved jet trajectory texture gradually appears in the cut’s inner wall , and in its bottom there are typical erosion pits and trailing phenomenon. The cut’s inner wall is mainly characterized by four types of damage features such as fracture through the crystal, fracture along the crystal, cut grooves or pits, and cement coverage, etc. It is worth noting that the four types of damage features appear at different locations in the cut at different impact angles, and this phenomenon is mainly caused by the deflection of jet, the direction of reflected flow movement, and the change in the reflection of shock wave and expansion wave. The vertical and horizontal jet components (in the same direction as the direction of propulsion), which play a dominant role in the destruction of the target, and the horizontal jet component, which is opposite to the direction of propulsion, play a secondary role in the erosion and polishing of the formed cut, but the degree of action varies under different impact angles. The macroscopic model of the abrasive water jet cutting process is established by combining the trajectory texture of cut’s inner wall and the observation results of the jet cutting process. The research results can provide a technical reference for further improving the efficiency of abrasive water jet cutting.

In this study,CFD method is used to analyze the performance of an automobile tube type shutter radiator. The local iterative method based on the local model iterative calculation is used to calculate the heat transfer performance of the integral radiator. At the same time,the resistance characteristics of the radiator are simulated by using porous media instead of the dispersion zone. The results show that the simulated heat dissipation of the whole loose zone can be estimated by using the results of several local models. It is feasible to estimate the heat dissipating capacity of the radiator by averaging the total mass flow rate of the radiator as the mass flow rate at each flat tube inlet. The results of the local iteration method and the porous medium model simulation agree well with the experimental results,and provide a new idea for the performance analysis of the integral radiator.

Objective: To investigate the expression of long non-coding RNA (lncRNA) H19 in mouse GC-1 cells in vitro and its effects on the proliferation and apoptosis of GC-1 cells., Methods: We established an in vitro hypoxia-reoxygenation model in GC-1 cells and detected the expression of lncRNA H19 in the GC-1 cells at different time points of reoxygenation injury by qRT-PCR. We determined the effects of silencing lncRNA H19 on the proliferation and apoptosis of the GC-1 cells by MTT and flow cytometry, the expressions of apoptosis-related proteins Bax and caspase-3 in the GC-1 cells by Western blot, and the expressions of microRNA-203a and PTEN by qRT-PCR and Western blot, respectively., Results: With the prolonging of the time of reoxygenation injury, the expression of lncRNA H19 was increased significantly in the GC-1 cells and peaked at 3-hour hypoxia and 12-hour reoxygenation, but that of microRNA-203a markedly decreased. Silencing lncRNA H19 enhanced the proliferation and inhibited the apoptosis of the GC-1 cells, and up-regulated the expression of microRNA-203a and down-regulated that of PTEN in the GC-1 cells., Conclusions: LncRNA H19 is highly expressed in GC-1 cells in vitro, which may influence the proliferation and apoptosis of GC-1 cells by regulating the microRNA-203a /PTEN signaling pathway.

Objective: To investigate the risk factors of systemic inflammatory response syndrome (SIRS) in patients undergoing flexible ureteroscopic lithotripsy based on enhanced recovery after surgery (ERAS). Methods: The clinical data of 243 kidney stone cases who underwent flexible ureteroscopic lithotripsy based on ERAS in the First Affiliated Hospital of Wannan Medical College from January 2016 to December 2017 were analyzed retrospectively. The cases were divided into two groups according to whether they had SIRS after surgery: SIRS group (26 cases) and non-SIRS group (217 cases). The age, gender, laterality of kidney stone, history of previous kidney stone surgery, degree of hydronephrosis, multiple kidney stones, length of operation time, white blood cell count of preoperative urine routine, result of preoperative urine culture, use of preoperative antibiotics, diabetes and other chronic diseases in the groups were collected and analyzed. Results: SIRS occurred in 26 cases in this study, which accounted for 10.7% (26/243). Multivariate analysis found that, moderate and severe hydronephrosis ( OR= 6.711, P= 0.008), stone burden ≥2 cm ( OR= 10.353, P< 0.001), length of operation time ≥ 60 min ( OR= 5.583, P= 0.011), white blood cell count of preoperative urine routine ≥25×10(6)/L ( OR= 6.195, P= 0.005), positive preoperative urine culture ( OR= 4.216, P= 0.011), diabetes and other chronic diseases ( OR= 4.532, P= 0.006) were the independent risk factors for postoperative SIRS ( P< 0.05). Conclusions: The occurrence of SIRS after flexible ureteroscopic lithotripsy based on ERAS is closely correlated with hydronephrosis, stone burden, length of operation time, white blood cell count of preoperative urine routine, positive preoperative urine culture, diabetes and other chronic diseases.

Objective: To evaluate the analgesic effect of intrarectal local anesthesia (IRLA) versus that of periprostatic nerve block anesthesia (PPNB) in initial transrectal ultrasound-guided prostate biopsy (TRUS-PB) for patients with different prostate volumes (PV)., Methods: A total of 253 patients undergoing initial TRUS-PB in our hospital from January 2014 to November 2017 were divided into three PV groups (<50 ml, 50－100 ml, and >100 ml), each again randomized into three subgroups (control, IRLA, and PPNB) with the random number table method. The pain during the procedure was assessed based on the Visual Analogue Scale (VAS) scores and the blind method was used by the biopsy operator, VAS valuator and data analyst., Results: Among the patients with PV <50 ml, the VAS scores in the blank control, IRLA, and PPNB subgroups were 4.39±0.87, 3.51±0.84 and 3.43±1.07, respectively, remarkably higher in the control than in the IRLA and PPNB groups (P<0.05), but with no statistically significant differences between the latter two (P>0.05). Among those with PV of 50－100 ml, the VAS scores in the three subgroups were 4.50±1.05, 4.38±1.13 and 3.38±1.44, respectively, markedly higher in the control and IRLA than in the PPNB group (P<0.05), but with no statistically significant differences between the former two groups (P>0.05). Among those with PV >100 ml, the VAS scores in the three subgroups were 5.19±1.05, 5.00±1.25 and 4.19±0.91, respectively, remarkably higher in the former two groups than in the latter (P<0.05), but with no statistically significant differences between the former two groups (P>0.05)., Conclusions: Either IRLA or PPNB can be recommended for initial TRUS-PB in patients with PV <50 ml, PPNB for those with PV of 50－100 ml, and PPNB with other painkillers for those with PV >100 ml.

A new clinical teaching mode of standardized treatment in colorectal cancer for fellows in training is reported here with good results. This one-year program included medical ethics education, humanistic management, pre job training, clinical thinking mode, surgery teaching, and computerized teaching. This new clinical teaching mode with distinct features is effective and introduced in this article.