共查询到17条相似文献,搜索用时 78 毫秒
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The size-dependent growth of dexamethasone sodium phosphate was studied in a MSMPR crystallizer. The Bransom, CR, ASL, MJ2 and MJ3 size-dependent growth rate models were discussed in details. Using experimental steady state population density data of dexamethasone sodium phosphate, the parameters of five size-dependent growth rate models were determined by the non-linear least - squares method. By comparison of experimental population density data and linear growth rate data with those calculated from five size-dependent growth rate models, it was found that the MJ3 model was the best one for predicting the growth of dexarnethasone sodium phosphate. 相似文献
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采用高灵敏度纳米粒度分析仪,对以SB粉为原料,HNO3为解胶剂制备的γ AlOOH溶胶的粒径分布进行了研究。考察了酸度、浓度、胶解温度对γ AlOOH溶胶的质点大小、粒径分布和稳定性的影响。结果表明,AlOOH溶胶质点的大小随着酸度的降低先呈下降趋势,之后很快上升。当n(H+)∶n(AlOOH)=0.07,溶胶粒度分布最窄;胶体的酸度决定了胶体质点的存在形态,在n(H+)∶n(AlOOH)=0.08~0.1时,AlOOH溶胶稳定;SB粉的质量分数<7%,AlOOH胶粒的粒径随SB粉的质量分数变化不大,AlOOH溶胶稳定,SB粉的质量分数对溶胶的粒度分布影响不明显;在温度高于80℃时,SB粉在HNO3作用下胶解稳定的AlOOH溶胶粒度分布窄,性质稳定。 相似文献
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γ-AlOOH溶胶的粒度和稳定性分析 总被引:1,自引:0,他引:1
采用高灵敏度纳米粒度分析仪,对以SB粉为原料,HNO3为解胶剂制备的γ-AlOOH溶胶的粒径分布进行了研究.考察了酸度、浓度、胶解温度对γ-AlOOH溶胶的质点大小、粒径分布和稳定性的影响.结果表明,AlOOH溶胶质点的大小随着酸度的降低先呈下降趋势,之后很快上升.当n(H+):n(AlOOH)=0.07,溶胶粒度分布最窄;胶体的酸度决定了胶体质点的存在形态,在n(H+):n(AlOOH)=0.08~0.1时,AlOOH溶胶稳定;SB粉的质量分数<7%,AlOOH胶粒的粒径随SB粉的质量分数变化不大,AlOOH溶胶稳定,SB粉的质量分数对溶胶的粒度分布影响不明显;在温度高于80℃时,SB粉在HNO3作用下胶解稳定的AlOOH溶胶粒度分布窄,性质稳定. 相似文献
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The influence of impeller diameter on crystal growth kinetics of borax decahydrate in a batch‐cooling crystallizer of non‐standard aspect ratio was evaluated. The dual‐impeller configuration consisted of a pitched‐blade turbine which was mounted below a straight‐blade turbine on a single shaft. Three different impeller‐to‐tank diameter ratios were investigated. In all experiments, mixing was conducted at just‐suspended impeller speed. To examine hydrodynamic conditions, mixing times were measured. The fluid flow pattern and velocity distribution were determined by computational fluid dynamics. Results showed that the smallest but also more regularly shaped crystals were produced in a system with standard diameter impellers. Product yield and power consumption were highest in this case. 相似文献
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Johannes Gerhard Martin Mnnigmann Wolfgang Marquardt 《Computers & Chemical Engineering》2008,32(12):2914-2919
In this article we address the steady state design of a nonlinear tryptophan biosynthesis model with guaranteed stability of the optimal solution in the presence of parametric uncertainty. The optimization based approach – denoted constructive nonlinear dynamics (CNLD) – is based on constraints that enforce a minimal distance in the space of the uncertain parameters between a stability boundary and the optimal solution. The results obtained with CNLD are compared to results recently presented by Chang and Sahinidis [Chang, Y. J., & Sahinidis, N. V. (2005). Optimization of metabolic pathways under stability considerations. Computers and Chemical Engineering, 29 (3), 467–479], where the optimization of the tryptophan biosynthesis model was addressed by a global optimization algorithm. CNLD takes the nonlinearities of the process exactly into account and satisfies the specified robustness criteria without being overly conservative. 相似文献
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以肉桂醛-2-呋喃甲酰腙与Co Cl2·6H2O为原料,在不同的反应条件下合成得到两个钴配合物,并通过FTIR、热重分析、X-射线单晶衍射等手段对其进行了表征。X-射线单晶衍射结果表明:两个配合物均为四角双锥构型,属单斜晶系。配合物Co(L)2(H2O)2属P21/c空间群,晶胞参数为a=1.706 2(2)nm,b=1.059 17(13)nm,c=0.742 00(9)nm;β=101.738(2)°,V=1.312 9(3)nm3,Z=2。配合物Co(L)2(Imz)2属C2/c空间群,晶胞参数为a=2.481 4(2)nm,b=0.848 96(8)nm,c=1.936 96(18)nm;β=121.132 0(10)°,V=3.492 7(6)nm3,Z=4。热重分析表明,两个配合物均有较高的热稳定性。 相似文献
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Porosity and Thermal Stability of Montmorillonite Pillared with Mixed Oxides of Lanthanum, Calcium and Aluminium 总被引:1,自引:0,他引:1
Montmorillonite intercalated with mixed pillars of lantana and alumina was prepared using a refluxed solution of aluminium chlorohydrate and lanthanum chloride. It is found that there are two main groups of pores in the pillared clays so prepared, one of which is around 8 Å, being close to that in alumina pillared clay (Al-PILC) and the other is about 14 Å. In contrast to the alumina pillared clays, a significantly larger specific surface area and micropore volume remained in LaAl-PILC after heating at high temperatures (700°C and 800°C). It seems that lanthanum ions react with the clay sheets during heating at high temperatures, resulting in a new porous solid phase which is thermally stable but has poor crystallinity. Calcium cations were introduced into the clays during the pillaring process. The calcium, distributed in the micropores of the product, LaAlCa-PILCs, further enhances the resistance to heating at high temperatures. After heating at 800°C, the BET surface area and micropore volume of a LaAlCa-PILC sample remained at about 138 m2/g and 0.05 cc/g, respectively, with a narrow pore size distribution in the micropore region. The influence of lanthanum and calcium on the pore structure as well as the evolution of pore structure in the PILCs upon heating at high temperatures are discussed in detail. 相似文献
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F. S. H. Lu B. R. Thomsen G. Hyldig D. M. B. Green-Petersen N. S. Nielsen C. P. Baron C. Jacobsen 《Journal of the American Oil Chemists' Society》2013,90(11):1673-1683
Marine phospholipids (PL) are potential ingredients for food fortification due to its numerous advantages. The main objective of this study was to investigate whether a fermented milk product fortified with a mixture of marine PL and fish oil had better oxidative stability than a fermented milk product fortified with fish oil alone. Fortification of a fermented milk product with marine PL was performed by incorporating 1 % w/w lipids, either in the form of neat oil or in the form of a pre-emulsion. Lipid oxidation was investigated in the neat emulsions and fortified products by the measurements of primary, secondary volatile oxidation products and tocopherol content upon 32 days storage at 2 °C and 28 days storage at 5 °C, respectively. Analyses of particle size distribution, viscosity and microbial growth were also performed. In addition, sensory attributes such as sour, fishy and rancid flavor/odor were evaluated in fortified products by a trained panel. The results obtained showed that incorporation of a mixture of marine PL and fish oil into fermented milk products decreased the oxidative stability and sensory quality of fortified products. The pH-dependent behavior of iron seemed to be the main factor that influenced the lipid oxidation in the marine PL emulsion and fermented milk system. In addition, both oxidative stability and sensory acceptability of fortified products varied depending on the quality of the marine PL used for fortification. 相似文献
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Ashok K. Shrestha Tony Howes Benu P. Adhikari Bhesh R. Bhandari 《Drying Technology》2013,31(2):239-247
The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1:0, 7:3, 3:7, and 0:1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80°C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (Tg ) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (aw ≥ 0.328 for SMP:MPP of 3:7 and 0:1 compared to aw ≥ 0.0.432 for SMP:MPP of 1:0 and 3:7). Addition of MP in SMP lowered the Tg values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical aw and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content. 相似文献
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Ashok K. Shrestha Tony Howes Benu P. Adhikari Bhesh R. Bhandari 《Drying Technology》2008,26(2):239-247
The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1:0, 7:3, 3:7, and 0:1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80°C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (Tg) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (aw ≥ 0.328 for SMP:MPP of 3:7 and 0:1 compared to aw ≥ 0.0.432 for SMP:MPP of 1:0 and 3:7). Addition of MP in SMP lowered the Tg values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical aw and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content. 相似文献