车用铝合金零件(金属支管)压装关键控制参数研究

在汽车冷却系统中,比如发动机缸盖等铝合金零件多采用旁通金属支管结构,以便与(橡胶)冷却管路进行连接,为了保证金属支管压装质量可靠性,采用理论分析和试验研究相结合的方法,分析了材料、表面质量、过盈量设计、密封胶等质量控制关键因素,提出了以上参数的最优控制参考范围,并给出了金属支管压装质量检验方法建议,为采用类似结构的车用铝合金零件的质量控制提供了思路及经验。

捷达轿车发动机与车架相连的橡胶金属支承的更换

捷达轿车发动机是由发动机上的两点和变速器上的一点通过三个橡胶金属衬套与车身相连的,由于三个支承有较好的弹性和吸振能力,可以使车辆运动时发动机相对于车身运动所产生的振动减为最小。这种橡胶支承在经过较长时间的使用后,由于经常承受较大力的作用和自身的老化会发生破损,如果橡胶支承发生破损,在行驶中不能对振动进行有效的控制,而使车辆在行驶中发生强烈震颤,尤其在不平路面。

The Cost-effectiveness Analysis of Percutaneous Transhepatic Metal Versus Plastic Biliary Stent Implantation for Treating Malignant Biliary Obstruction (Multiple Center Investigation)

Objective: To compare metal versus plastic biliary stent implantation for treatment of malignant biliary obstruction in cost-effectiveness ratio (CER). Methods: Percutaneous transhepatic self-expandable metal stent (MS, n=61) or 10F plastic stent (PS, n=34) implantation was performed in 95 patients with malignant biliary obstruction in three hospitals of Guangdong province. All patients were followed up until death or at least one year after the procedure. Kaplan-Meier analysis was used to compare the survival and stent patency rates of the patients in the two groups. CERs of two groups were calculated. The main indexes were CERsurvival period (total cost/median survival period), CERpatency period (total cost/median patency period). Results: The total costs of treatment were 53177±3139 yuan (RMB) in MS group and 42564±4950 yuan (RMB) in PS group respectively (P>0.05). CER in MS group was superior to that in PS group (CERsurvival period was 237.4 yuan /d vs 452.6 yuan /d, respectively; CERpatency period was 231.2 yuan /d vs 472.9 yuan /d, respectively). Conclusion: The metal stent implantation is superior to the plastic stent in the CER for treatment of malignant biliary obstruction.

Double layered self-expanding metal stents for malignant esophageal obstruction, especially across the gastroesophageal junction

AIM: To evaluate the clinical outcomes of double-layered self-expanding metal stents (SEMS) for treatment of malignant esophageal obstruction according to whether SEMS crosses the gastroesophageal junction (GEJ). METHODS: Forty eight patients who underwent the SEMS insertion for malignant esophageal obstruction were enrolled. Patients were classified as GEJ group (SEMS across GEJ, 18 patients) and non-GEJ group (SEMS above GEJ, 30 patients) according to SEMS position. Double layered (outer uncovered and inner covered stent) esophageal stents were placed. RESULTS: The SEMS insertion and the clinical improvement were achieved in all patients in both groups. Stent malfunction occurred in seven patients in the GEJ group and nine patients in the non-GEJ group. Tumor overgrowth occurred in five and eight patients, respectively, food impaction occurred in one patient in each group, and stent migration occurred in one and no patient, respectively. There were no significant differences between the two groups. Reflux esophagitis occurred more frequently in the GEJ group (eight vs five patients, P = 0.036) and was controlled by proton pump inhibitor. Aspiration pneumonia occurred in zero and five patients, respectively, and tracheoesophageal fistula occurred in zero and two patients, respectively. CONCLUSION: Double-layered SEMS are a feasible and effective treatment when placed across the GEJ for malignant esophageal obstruction. Double-layered SEMS provide acceptable complications, especially migration, although reflux esophagitis is more common in the GEJ group.

Metal stenting to resolve post-photodynamic therapy stricture in early esophageal cancer

Photodynamic therapy (PDT) is an established endoscopic technique for ablating Barrett's esophagus with high-grade dysplasia or early-stage intraepithelial neoplasia. The most common clinically significant adverse effect of PDT is esophageal stricture formation. The strictures are usually superficial and might be dilated effectively with standard endoscopic accessories, such as endoscope balloon or Savary dilators. However, multiple dilations might be required to achieve stricture resolution in some cases. We report the case of stricture that recurred after dilation with a bougie, which was completely relieved by a self-expandable metal stent.

Endoscopic ultrasound-guided biliary drainage with placement of a fully covered metal stent for malignant biliary obstruction

AIM:To determine the utility of endoscopic ultrasoundguided biliary drainage(EUS-BD)with a fully covered self-expandable metal stent for managing malignant biliary stricture. METHODS:We collected data from 13 patients who presented with malignant biliary obstruction and underwent EUS-BD with a nitinol fully covered selfexpandable metal stent when endoscopic retrograde cholangiopancreatography(ERCP)fails.EUS-guided choledochoduodenostomy(EUS-CD)and EUS-guided hepaticogastrostomy(EUS-HG)was performed in 9 patients and 4 patients,respectively. RESULTS:The technical and functional success rate was 92.3%(12/13)and 91.7%(11/12),respectively. Using an intrahepatic approach(EUS-HG,n=4),there was mild peritonitis(n=1)and migration of the metal stent to the stomach(n=1).With an extrahepatic approach(EUS-CD,n=10),there was pneumoperitoneum(n=2),migration(n=2),and mild peritonitis (n=1).All patients were managed conservatively with antibiotics.During follow-up(range,1-12 mo),there was re-intervention(4/13 cases,30.7%)necessitated by stent migration(n=2)and stent occlusion(n=2). CONCLUSION:EUS-BD with a nitinol fully covered self-expandable metal stent may be a feasible and effective treatment option in patients with malignant biliary obstruction when ERCP fails.

Biliary drainage of the common bile duct with an enteral metal stent

In this case report we present an elderly patient who was referred to our hospital with recurrent episodes of cholangitis that persisted after placement of fi ve metal stents for a distal common bile duct(CBD) stenosis.All metal stents were endoscopically removed from the CBD by forceps after balloon dilatation of the papilla.A profoundly dilated CBD with sludge and concrements was seen.To ensure adequate bile drainage an enteral metal stent was inserted in the CBD.This case shows that proximally migrated uncovered metal stents in the CBD can be safely removed endoscopically under certain circumstances.We suggest that in the case of a CBD drainage problem due to an extremely dilated CBD,placement of an enteral metal stent in the CBD could be considered,especially in patients who are unfi t for surgery.

Biocompatibility of vascular stents manufactured using metal injection molding in animal experiments

This study aimed to evaluate the feasibility and safety of a novel stent manufactured by metal injection molding(MIM)in clinical practice through animal experiments.Vessel stents were prepared using powder injection molding technology to considerably improve material utilization.The influence of MIM carbon impurity variation on the mechanical properties and corrosion resistance of 316L stainless steel was studied.In vitro cytotoxicity and animal transplantation tests were also carried out to evaluate the safety of MIM stents.The results showed that the performance of 316L stainless steel was very sensitive to the carbon content.Carbon fluctuations should be precisely controlled during MIM.All MIM stents were successfully implanted into the aortas of the dogs,and the MIM 316L stents had no significant cytotoxicity.The novel intravascular stent manufactured using MIM can maintain a stable form and structure with fast endothelialization of the luminal surface of the stent and ensure long-term patency in an animal model.The novel intravascular stent manufactured using MIM demonstrates favorable structural,physical,and chemical stability,as well as biocompatibility,offering promising application in clinical practice.

Clinical benefit of radiation therapy and metallic stenting for unresectable hilar cholangiocarcinoma

AIM： To determine the efficacy of external beam radiotherapy （EBRT）, with or without intraluminal brachytherapy （ILBT）, in patients with non-resected locally advanced hilar cholangiocarcinoma.METHODS： We analyzed 64 patients with locally advanced hilar cholangiocarcinoma, including 25 who underwent resection （17 curative and 8 non-curative）, 28 treated with radiotherapy, and 11 who received best supportive care （BSC）. The radiotherapy group received EBRT （50 Gy, 30 fractions）, with 11 receiving an ad- ditional 24 Gy （4 fractions） ILBT by iridium-192 with remote after loading. ILBT was performed using percu-taneous transhepatic biliary drainage （PTBD） route. Uncovered metallic stents （UMS） were inserted into nonresected patients with obstructive jaundice, with the exception of four patients who received percutaneous transhepatic biliary drainage only. UMS were placed endoscopically or percutaneously, depending on the initial drainage procedure. The primary endpoints were patient death or stent occlusion. Survival time of patients in the radiotherapy group was compared with that of patients in the resection and BSC groups. Stent patency was compared in the radiotherapy and BSC groups.RESULTS： No statistically significant differences in patient characteristics were found among the resection, radiotherapy, and BSC groups. Three patients in the radiotherapy group and one in the BSC group did not receive UMS insertion but received PTBD alone; cholangitis occurred after endoscopic stenting, and patients were treated with PTBD. A total of 16 patients were administered additional systemic chemotherapy （5-fluorouracil-based regimen in 9, S-1 in 6, and gemcitabine in 1）. Overall survival varied significantly among groups, with median survival times of 48.7 mo in the surgery group, 22.1 mo in the radiotherapy group, and 5.7 mo in the BSC group. Patients who underwent curative resection survived significantly longer than those who were not candidates for surgery （P = 0.0076）. Cumulative survival in the radiotherapy group was significantly longer than in the BSC group （P = 0.0031）, but did not differ significantly from those in the non-resection group. Furthermore, the median survival time of patients in the radiotherapy group who were considered for possible resection （excluding the seven patients who were not candidates for surgery due to comorbid disease or age） was 25.9 mo. Stent patency was evaluated only in the 24 patients who received a metallic stent. Stent patency was significantly longer in the radiotherapy than in the BSC group （P = 0.0165）. Biliary drainage was not eliminated in any patient. To determine the efficacy of ILBT, we compared