Foam stability affects the efficacy and incidence of side effects of foam sclerotherapy. Exploring the relationship between foam pressure difference and foam stability can provide ideas and basis for obtaining more stable foam. In the experiment, sodium cod liver oleate foam was selected, and poloxamer 188 (concentration of 0%, 4%, 8%, 12%) was added to realize the change of foam pressure. By using the self-written program to process the foam pictures, the foam pressure difference and the relationship between the foam stability indicators (water separation rate curve, half-life) and the foam pressure difference were obtained. The results showed that at first the foam pressure increased with the increase of the concentration, and then it decreased with the increase of the concentration and reached a peak at the concentration of 4%. The foam pressure difference decreases continuously with the increase of decay time. When the additive concentration is low, the foam average pressure difference increases. And if the additive concentration is too high, the foam average pressure difference decreases. The smaller the foam pressure difference is, the better the foam stability is. This paper lays a foundation for the research on the stability of foam hardener.
Three dimensional (3D) printing is considered as an advanced manufacturing technology because of its additive nature. Electron beam melting (EBM) is a widely used 3D printing processes for the manufacturing of metal components. However, the products printed via this process generally contain micro porosities which affect mechanical properties, especially the fatigue property. In this paper, two types of EBM printed samples of the Ti-6Al-4V alloy, one with a round cross section and the other with a triangle cross section, were employed to investigate the existence of porosities using computed tomography (CT). Statistical analyses were conducted on the number, volume, shape, and distribution of pores. The results show that small pores (less than 0.000 2 mm3) account for 80% of all pores in each type of samples. Additionally, to some extent, the shape of sample has influence on the number of micro porosities in EBM made Ti-6Al-4V. The sphericity of the pores is relatively low and is inversely proportional to pore volume. It is found that re-melting on the free surface effectively reduce pore density near the surface. This study may help produce a medical implant with better fatigue resistance.
Objective To analyze the effect of monitoring and modulating the portal vein pressure and blood flow during living donor liver transplantation （LDLT） on preventing small-for-size-syndrome (SFSS). Methods Data of forty-four LDLT recipients between Oct.2007 and Oct.2008 were reviewed. Actual graft-to-recipient weight ratio（GRWR）, portal vein flow and pressure during operation and syndrome of SFSS after operation were recorded. The patients received splenectomy or splenic artery ligation according to actual GRWR, portal vein flow and pressure and WBC. Relationships between patients’ GRWR, portal vein flow, portal vein pressure and occurrence of SFSS were analyzed. Results Six patients received splenectomy and 7 patients received splenic artery ligation to decrease the portal vein flow and pressure during the operation. The portal vein flow and pressure decreased after splenectomy （Plt;0.05）. The portal vein pressure decreased （Plt;0.05） and the portal vein flow had no significant change after splenic artery ligation （P＞0.05）. No SFSS occurred after operation. Conclusion Modulation of portal vein flow and pressure by splenectomy or splenic artery ligation during LDLT operation can decrease the portal vein flow and pressure, and which can prevent the incidence of SFSS.
Objective To observe efficacy of rapamycin combined with sorafenib in hepatocellular carcinoma (HCC) patients with tumor recurrence after liver transplantation beyond Milan criteria. Methods Forty-one beyond Milan criteria HCC patients who underwent the classic orthotopic liver transplantation without bypass and the tumor postoperatively recurred in the Tianjin First Center Hospital from February 1, 2012 to August 31, 2015 were collected retrospectively, then were divided into a local treatment group (n=21) and a comprehensive treatment group (n=20). The local treatment included the surgical resection, radiofrequency ablation, transcatheter arterial chemoembolization, radioactive seed implantation, etc.. The comprehensive treatment was on the basis of the local treatment plus rapamycin in combination with sorafenib. Results There were 12 patients with stable disease and 9 patients with progressive disease in the local treatment group. There were 12 patients with partial response, 10 patients with stable disease and 8 patients with progressive disease in the comprehensive group. In the local treatment group and the comprehensive treatment group, the median survival time were 9 months and 12 months, and the 1-year and 2-year survival rates after the recurrence were 14% versus 55%, 0 versus 15%, respectively. The survival of the comprehensive treatment group was significantly better than that of the local treatment group (P<0.01). Conclusion Combination of rapamycin and sorafenib in HCC patients with tumor recurrence after liver transplantation beyond Milan criteria can significantly improve survival time of patient with recurrence.
Muscle atrophy of the residual limb after lower-limb amputation is a disadvantage of amputees' rehabilitation. To investigate the biomechanics mechanism of muscle atrophy of the residual limb, we built a finite element model of a residual limb including muscle, skeletons and main vessels based on magnetic resonance images of a trans-femoral amputee, and studied the biomechanics effects of the socket of the lower-limb prosthesis on the soft tissue and vessels in the residual limb. It was found that the descending branch of the lateral femoral circumflex artery suffered the most serious constriction due to the extrusion, while that of the deep femoral artery was comparatively light. Besides, the degree of the constriction of the descending branch of the lateral femoral circumflex vein, femoral vein and deep femoral vein decreased in turn, and that of the great saphenous vein was serious. The stress-strain in the anterior femoral muscle group were highest, while the stress concentration of the inferior muscle group was observed at the end of the thighbone, and other biomechanical indicators at the inferior region were also high. This study validated that the extrusion of the socket on the vessels could cause muscle atrophy to some degree, and provided theoretical references for learning the mechanism of muscle atrophy in residual limb and its effective preventive measures.
This study analyzed the inherent relation between arterial blood mass flow and muscle atrophy of residual limb to provide some necessary information and theoretical support for the clinical rehabilitation of lower limb amputees. Three-dimensional arterial model reconstruction was performed on both intact side and residual limb of a unilateral transfemoral amputee who is the subject. Then hemodynamic calculation was carried out to comparatively analyze the mass flow state at each arterial outlet of both lower extremities. The muscle atrophy ratio of residual limb was calculated by measuring the cross-sectional area of bilateral muscles. Based on the blood supply relationship, the correlation between arterial blood flow reduction ratio and muscle atrophy ratio was discussed. The results showed that the mass flow of superficial femoral arteries and lateral circumflex femoral arteries severely reduced. Meanwhile rectus femoris, vastus lateralis and vastus medialis which were fed by these arteries showed great atrophy too. On the contrary, the mass flow of deep femoral arteries and medial femoral circumflex arteries slightly reduced. Meanwhile gracilis, adductor longus, long head of biceps which were fed by these arteries showed mild atrophy too. These results indicated that there might be a positive and promotion correlation between the muscle atrophy ratio and the blood mass flow reduction ratio of residual limb during rehabilitation.
Biodegradable stents (BDSs) are the milestone in percutaneous coronary intervention(PCI). Biodegradable polymeric stents have received widespread attention due to their good biocompatibility, moderate degradation rate and degradation products without toxicity or side effects. However, due to the defects in mechanical properties of polymer materials, the clinical application of polymeric BDS has been affected. In this paper, the BDS geometric configuration design was analyzed to improve the radial strength, flexibility and reduce the shrinkage rate of biodegradable polymeric stents. And from the aspects of numerical simulation, in vitro experiment and animal experiment, the configuration design and mechanical properties of biodegradable polymeric stents were introduced in detail in order to provide further references for the development of biodegradable polymeric stents.
This study aims to overcome the shortcomings such as low efficiency, high cost and difficult to carry out multi-parameter research, which limited the optimization of infusion bag configuration and manufacture technique by experiment method. We put forward a fluid cavity based finite element method, and it could be used to simulate the stress distribution and deformation process of infusion bag under external load. In this paper, numerical models of infusion bag with different sizes was built, and the fluid-solid coupling deformation process was calculated using the fluid cavity method in software ABAQUS subject to the same boundary conditions with the burst test. The peeling strength which was obtained from the peeling adhesion test was used as failure criterion. The calculated resultant force which makes the computed peeling stress reach the peeling strength was compared with experiment data, and the stress distribution was analyzed compared with the rupture process of burst test. The results showed that considering the errors caused by the difference of weak welding and eccentric load, the flow cavity based finite element method can accurately model the stress distribution and deformation process of infusion bag. It could be useful for the optimization of multi chamber infusion bag configuration and manufacture technique, leading to cost reduction and study efficiency improvement.
This study explored the variation of bursting force of multi-chamber infusion bag with different geometry size, providing guidance for its optimal design. Models of single-chamber infusion bag with different size were established. The finite element based on fluid cavity method was adopted to calculate the fluid-solid coupling deformation process of infusion bag to obtain corresponding critical bursting force. As a result, we proposed an empirical formula predicting the critical bursting force of one chamber infusion bag with specified geometry size. Besides, a theoretical analysis, which determines the force condition of three chamber infusion bag when falling from high altitude, was conducted. The proportion of force loaded on different chamber was gained. The results indicated that critical bursting force is positively related to the length and width of the chamber, and negatively related to the height of the chamber. While the infusion bag falling, the impact force loaded on each chamber is proportional to the total liquid within it. To raise the critical bursting force of in fusion bag, a greater length and width corresponding to reduced height are recommended considering the volume of liquid needed to be filled in.
It has been found that the incidence of cardiovascular disease in patients with lower limb amputation is significantly higher than that in normal individuals, but the relationship between lower limb amputation and the episodes of cardiovascular disease has not been studied from the perspective of hemodynamics. In this paper, numerical simulation was used to study the effects of amputation on aortic hemodynamics by changing peripheral impedance and capacitance. The final results showed that after amputation, the aortic blood pressure increased, the time averaged wall shear stress of the infrarenal abdominal aorta decreased and the oscillatory shear index of the left and right sides was asymmetrically distributed, while the time averaged wall shear stress of the iliac artery decreased and the oscillatory shear index increased. The changes above were more significant with the increase of amputation level, which will result in a higher incidence of atherosclerosis and abdominal aortic aneurysm. These findings preliminarily revealed the influence of lower limb amputation on the occurrence of cardiovascular diseases, and provided theoretical guidance for the design of rehabilitation training and the optimization of cardiovascular diseases treatment.