ABSTRACT
To improve the efficiency of frozen soil excavation, the new shaft tunneling machine was developed. The new shaft tunneling machine exerts pressure on the frozen soil through the cutter under the joint action of its own gravity, the drum rotational force and the inertia force, and the frozen soil is damaged. By unique way of breaking frozen soil to improve the efficiency of frozen soil excavation, the drum rotation speed is one of the factors affecting the performance of frozen soil excavation. This article applies SolidWorks software to establish the model of cutter breaking frozen soil, takes advantage of Hyper Mesh finite element software coupled with LS-DYNA solver to acquire the regular pattern of change in the force change, frozen soil stress-strain and specific energy of cutter crushing frozen soil, etc., which analyzes the destruction of frozen soil when the drum of the new shaft tunneling machine is rotating at the speed of 25-40 rpm. Combine with field test to investigate the mechanism of cutter breaking frozen soil under the optimal drum rotation speed. The investigation results demonstrate that: when frozen soil's self-bearing capacity is lower than the force of cutter, it breaks up and detaches from the soil body, and frozen soil undergoes tensile, compressive and shear damages. For this research, it is instructive for practical engineering.
ABSTRACT
Transcatheter arterial chemoembolization (TACE), aiming to block the hepatic artery for inhibiting tumor blood supply, became a popular therapy for hepatocellular carcinoma (HCC) patients. Traditional TACE formulation of anticancer drug emulsion in ethiodized oil (i.e., Lipiodol®) and gelatin sponge (i.e., Gelfoam®) had drawbacks on patient tolerance and resulted in undesired systemic toxicity, which were both significantly improved by polymeric beads, microparticles, or hydrogels by taking advantage of the elegant design of biocompatible or biodegradable polymers, especially amphiphilic polymers or polymers with both hydrophilic and hydrophobic chains, which could self-assemble into proposed microspheres or hydrogels. In this review, we aimed to summarize recent advances on polymeric embolization beads or hydrogels as TACE agents, with emphasis on their material basis of polymer architectures, which are important but have not yet been comprehensively summarized.
ABSTRACT
OBJECTIVE: To investigate the effects of "Neiguan" (PC 6)-electroacupunture (EA) preconditioning on the myocardium and its mast cells in myocardial ischemia/reperfusion (MI/R) rats. METHODS: Eighteen male SD rats were randomly assigned to sham group, model (IR) group and EA group (n=6/ group). MI/R model was established by occlusion of the descending anterior branch of the coronary artery. Blood samples were taken from the femoral vein before MI (T0), EA for 30 min (T1), 30 min after MI (T2), 30 min after MI/R (T3) and 120 min after MI/R (T4) for assaying serum tumor necrosis factor (TNF)-alpha and histamine contents by using ELISA. Serum lactate dehydrogenase (LDH) and creatinkinase isoenzyme (CK-MB) levels were measured at T0, T3 and T4 by using an automatic biochemistry analyzer. The infarct size was detected by Evan's blue and tetrazolium chloride (TTC) staining. Myocardial TNF-alpha and histamine contents were detected by ELISA. The percentage of mast cell degranulation was determined by toluidine blue staining. RESULTS: Following MI/R, serum LDH and CK-MB levels at phase T3 and T4, serum TNF-alpha and histamine contents at phase T2 and T3, and myocardial mast cell degranulation rate increased significantly, and myocardial TNF-alpha and histamine contents decreased in model group in comparison with pre-MI/R (P < 0.05). Compared with IR model group, serum LDH and CK-MB levels at phase T3 and T4, myocardial TNF-alpha and histamine contents all decreased significantly (P < 0.05), but serum TNF-al infarct size was remarkably smaller in EA group than that in IR model group (P < 0.05). CONCLUSION: "Neiguan" (PC 6)-EA preconditioning has a cardioprotective effect on the ischemia-reperfusion myocardium by promoting mast cell degranulation.
