Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood puri...Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood purification.In this study,the sulfonated polyethersulfone(SPES) was synthesized through an electrophilic substitution reaction,and PES/SPES blending membranes were prepared.The characterization of the SPES was studied by FTIR.The water adsorption and water contact angle experiments show that the hydrophilicity of PES/SPES blend membrane was improved as for the sulfonate group existing in the SPES.Moreover,PES/SPES blend membrane could effectively reduce bovine serum albumin adsorption and prolong the blood coagulation time compared with the PES membrane,thereby improving blood compatibility.展开更多
By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades ...By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point（BEP）, the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump QBEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.展开更多
基金Supported by the Special Fund for International Cooperation Projects of China (2005DFA50160)
文摘Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood purification.In this study,the sulfonated polyethersulfone(SPES) was synthesized through an electrophilic substitution reaction,and PES/SPES blending membranes were prepared.The characterization of the SPES was studied by FTIR.The water adsorption and water contact angle experiments show that the hydrophilicity of PES/SPES blend membrane was improved as for the sulfonate group existing in the SPES.Moreover,PES/SPES blend membrane could effectively reduce bovine serum albumin adsorption and prolong the blood coagulation time compared with the PES membrane,thereby improving blood compatibility.
基金supported by the National Natural Science Foundation of China(Grant No.51176088)
文摘By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point（BEP）, the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump QBEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.
