In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curv...In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curves, the bed density stability and the average bubble rise velocity Uaunder different agitation conditions. The results indicated that a lower bed pressure drop(without considering lower gas velocity in a fixed bed stage) and higher minimum fluidized velocity are achieved with increasing agitation speed.The height d(distance between the lower blades and air distribution plate) at which the agitation paddle was located had a considerable effect on the stability of the bed density at 9.36 cm/s < U < 10.70 cm/s. The higher the value of d, the better the stability, and the standard deviation of the bed density fluctuation r dropped to 0.0364 g/cm^3 at the ideal condition of d = 40 mm. The agitation speed also had a significant influence on the fluidization performance, and r was only 0.0286 g/cm^3 at an agitation speed of N = 75 r/min. The average bubble rise velocity decreased significantly with increasing agitation speed under the operating condition of 1.50 cm/s < U–U_(mf)< 3.50 cm/s. This shows that appropriate agitation contributes to a significant improvement in the fluidization quality in a fluidized bed, and enhances the separation performance of a fluidized bed.展开更多
Objective： To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty （FBDALK）. Methods： This is a retrospe...Objective： To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty （FBDALK）. Methods： This is a retrospective analysis of patients who were diagnosed with advanced keratoconus between 2011 and 2014 in our hospital. The base of the cone in all patients did not exceed the central cornea at a 6-mm range. The FBDALK was performed by a same surgeon. All patients had a complete corneal suture removal and the follow-up records were intact. Patients who had graft-bed misalignment or who were complicated with a cataract or glaucoma were excluded. Uncorrected visual acuity （UCVA）, best spectacle corrected visual acuity （BSCVA）, and Pentacam examination data were recorded at two years postoperatively. The recorded data included the superior-inferior （S-I） and nasal-temporal （N-T） corneal thickness differences in 2, 4, 6, and 8 mm diameter concentric circles with the corneal apex as the center （S-I2 mm, S-14 mm, S-I6mm,, S-I8mm, N-T2mm, N-T4 mm, N-T6 mm, and N-T8 mm）, the linear, X-axis, and Y-axis distance between the corneal pupillary center and the cornea apex, total corneal astigmatism at a zone of 3 mm diameter from the corneal apex （TA3 mm）, the astigmatic vector values J0 and J4s, and the corneal total higher-order aberration for 3 and 6 mm pupil diameters （HOA3 mm and HOA6mm）. Statistical analysis was performed by SPSS 15.0. Results： A total of 47 eyes of 46 patients met the criteria and were included in this study. The mean follow-up time was （28±7） months. The mean UCVA was 0.45±0.23 （IogMAR） （MAR： minimum angle of resolution） and the mean BSCVA was 0.19±0.15 （IogMAR）, which were all sig- nificantly positively correlated with postoperative TA3 mm and HOA3 turn. The mean S-I corneal thickness differences were （44.62±37.74） IJm, and the mean N-T was （38.57±32.29） pm. S-12 mm was significantly positively correlated with J0 （r=0.31）, J45 （r=0.42）, HOA3 mm （r=0.37）, and HOA6 mm （r=0.48）. S-14 mm and S-Is mm were significantly positively corre- lated with HOA3 mm （t=0.30, t=0.40） and HOA6 mm （r=0.46, r=0.35）. The X-axis distance between corneal pupillary center and corneal apex was significantly positively correlated with J45 （r=0.29）. Conclusions： In patients with ad- vanced keratoconus after FBDALK, the unevenly distributed thickness at corneal pupillary area and the misalignment of corneal apex and pupillary center might cause significant regular and irregular astigmatism, which affected the postoperative visual quality.展开更多
基金financial support by the National Key Programs for Fundamental Research and Development of China(No.2012CB214904)the National Natural Science Foundation of China(Nos.51174203,51134022)
文摘In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curves, the bed density stability and the average bubble rise velocity Uaunder different agitation conditions. The results indicated that a lower bed pressure drop(without considering lower gas velocity in a fixed bed stage) and higher minimum fluidized velocity are achieved with increasing agitation speed.The height d(distance between the lower blades and air distribution plate) at which the agitation paddle was located had a considerable effect on the stability of the bed density at 9.36 cm/s < U < 10.70 cm/s. The higher the value of d, the better the stability, and the standard deviation of the bed density fluctuation r dropped to 0.0364 g/cm^3 at the ideal condition of d = 40 mm. The agitation speed also had a significant influence on the fluidization performance, and r was only 0.0286 g/cm^3 at an agitation speed of N = 75 r/min. The average bubble rise velocity decreased significantly with increasing agitation speed under the operating condition of 1.50 cm/s < U–U_(mf)< 3.50 cm/s. This shows that appropriate agitation contributes to a significant improvement in the fluidization quality in a fluidized bed, and enhances the separation performance of a fluidized bed.
基金Project supported by the Medical Scientific Research Foundation of Zhejiang Province(No.2018ZD007),China
文摘Objective： To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty （FBDALK）. Methods： This is a retrospective analysis of patients who were diagnosed with advanced keratoconus between 2011 and 2014 in our hospital. The base of the cone in all patients did not exceed the central cornea at a 6-mm range. The FBDALK was performed by a same surgeon. All patients had a complete corneal suture removal and the follow-up records were intact. Patients who had graft-bed misalignment or who were complicated with a cataract or glaucoma were excluded. Uncorrected visual acuity （UCVA）, best spectacle corrected visual acuity （BSCVA）, and Pentacam examination data were recorded at two years postoperatively. The recorded data included the superior-inferior （S-I） and nasal-temporal （N-T） corneal thickness differences in 2, 4, 6, and 8 mm diameter concentric circles with the corneal apex as the center （S-I2 mm, S-14 mm, S-I6mm,, S-I8mm, N-T2mm, N-T4 mm, N-T6 mm, and N-T8 mm）, the linear, X-axis, and Y-axis distance between the corneal pupillary center and the cornea apex, total corneal astigmatism at a zone of 3 mm diameter from the corneal apex （TA3 mm）, the astigmatic vector values J0 and J4s, and the corneal total higher-order aberration for 3 and 6 mm pupil diameters （HOA3 mm and HOA6mm）. Statistical analysis was performed by SPSS 15.0. Results： A total of 47 eyes of 46 patients met the criteria and were included in this study. The mean follow-up time was （28±7） months. The mean UCVA was 0.45±0.23 （IogMAR） （MAR： minimum angle of resolution） and the mean BSCVA was 0.19±0.15 （IogMAR）, which were all sig- nificantly positively correlated with postoperative TA3 mm and HOA3 turn. The mean S-I corneal thickness differences were （44.62±37.74） IJm, and the mean N-T was （38.57±32.29） pm. S-12 mm was significantly positively correlated with J0 （r=0.31）, J45 （r=0.42）, HOA3 mm （r=0.37）, and HOA6 mm （r=0.48）. S-14 mm and S-Is mm were significantly positively corre- lated with HOA3 mm （t=0.30, t=0.40） and HOA6 mm （r=0.46, r=0.35）. The X-axis distance between corneal pupillary center and corneal apex was significantly positively correlated with J45 （r=0.29）. Conclusions： In patients with ad- vanced keratoconus after FBDALK, the unevenly distributed thickness at corneal pupillary area and the misalignment of corneal apex and pupillary center might cause significant regular and irregular astigmatism, which affected the postoperative visual quality.
