乙醇-水溶剂中5′-尿苷酸二钠溶解度测定与关联

采用内置双光路激光检测器,在293.2—318.2 K温度范围内,测定了5′-尿苷酸二钠在纯水及不同乙醇-水混合溶剂中的溶解度。分别用R-K方程、λh方程和Wilson方程3种溶解度模型,采用最小二乘法关联实验数据,并对比不同溶解度模型。结果表明,在乙醇质量分数为0—0.65区间内,5′-尿苷酸二钠溶解度随着温度的升高而增大,随乙醇质量分数的增大而显著减小,λh方程对5′-尿苷酸二钠溶解度关联效果最好。将λ,h表达为乙醇质量分数的函数,并用于内插计算,精度满足工程要求。     

乙醇-水混合溶剂中5′-尿苷酸二钠的结晶介稳区

采用双光路激光法,在293.2～318.2 K温度范围内,研究了5′-尿苷酸二钠在不同比例乙醇-水混合溶剂中的溶解与超溶解特性,得到了5′-尿苷酸二钠的结晶介稳区。采用λh方程关联了4个体系的溶解度数据,进而分别求得各体系下的混合焓和结晶焓。同时,探讨了搅拌转速、pH值和钠离子浓度对结晶介稳区的影响。实验结果表明,与温度相比较,乙醇质量分数是影响溶解度和超溶解度的主要因素;随乙醇质量分数的增大,5′-尿苷酸二钠的溶解度和超溶解度显著减小;在相同条件下,溶液pH值和钠离子浓度的升高,以及搅拌转速的降低均会增大5′-尿苷酸二钠结晶介稳区的宽度。     

盐酸大观霉素在纯水及丙酮-水混合溶剂中的溶解度测定与关联

激光法测定了9～55℃盐酸大观霉素在纯水及9～30℃不同丙酮．水比例混合溶剂中的溶解度。采用线性和非线性最小二乘法将实验数据关联为R-K方程和λh方程两种形式。结果表明。λh方程的关联效果令人满意。将λ,h表达为丙酮浓度的函数,并用于内插计算。精度满足工程需要。     

21-脱氧可的松在不同溶剂中的溶解度测定与关联

采用合成法测定了21-脱氧可的松在丙酮,乙酸乙酯,甲醇,乙醇,1,4-二氧六环中的溶解度。运用Apelblat方程和λh方程对所测数据进行了关联,取得了令人满意的关联结果,且Apelblat方程优于λh方程。结果表明,21-脱氧可的松在五种溶剂中的溶解度都随温度升高而增大,且在1,4-二氧六环和乙醇中对温度比较敏感。该结果有利于为21-脱氧可的松选择合适的重结晶溶剂,并且为21-脱氧可的松的理论研究提供了重要的固液相平衡数据。     

喹诺酮类药物水溶解度的测定与关联

采用平衡法测定了293.15～323.15 K温度范围内6种喹诺酮类药物的水溶解度数据,并运用λh方程进行了关联,确定了方程参数,6种药物的计算与实验值平均相对偏差最大为10.1%.结果表明,实验范围内6种喹诺酮类药物的水溶解度均较小,且分别随温度的升高而略有增加.     

枞酸在四种醇类溶剂中的溶解度测定与关联

采用激光监视技术判定平衡点,由动态法测定了枞酸在甲醇、无水乙醇、正丙醇、正丁醇中的固液溶解度,实验测定温度由282 K至320 K,用λh方程、Wilson方程、简化方程分别对溶解度实验数据进行关联.结果表明,枞酸在四种醇类溶剂中的溶解度均随温度的升高而增大,且在不同溶剂中枞酸溶解度有较大的差异,大小顺序为:正丁醇＞正...     

丁二酸在五种有机溶剂中溶解度测定及关联

采用激光监视技术由动态法测定了丁二酸在环己醇、环己酮、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺和冰醋酸中的固液平衡数据,实验测定温度由室温至近353 K,并分别用λh方程和NRTL方程对溶解度实验数据进行关联.根据实验数据可以看出丁二酸在五种溶剂中的溶解度均随温度的增加而增大,并且在不同溶剂中丁二酸的溶解度有较大差异.溶解度实验数据用λh方程关联和NRTL方程模型拟合结果的最大平均相对误差分别为3.98%和5.13%.结果表明λh方程模型和NRTL方程模型均能很好地关联丁二酸在五种有机溶剂中的溶解度数据.     

从RNA酶解液中分离5-尿苷酸

采用2根强酸性阳离子交换柱、1根弱碱性阴离子交换柱和1根强碱性阴离子交换柱进行4柱串联,可以从RNA酶解液中分离得到5-尿苷酸,而不混有其它核苷酸,并对离子交换树脂种类、树脂量、洗脱剂等作了进一步研究。结果表明,采用4柱串联分离5-尿苷酸,其总收率达到92．1％、结晶纯度达到86％以上。     

乙醇-水混合溶剂中尿苷酸浓度与溶液密度的关系

获取尿苷酸溶析结晶动力学参数须测定其溶液浓度变化,针对密度法浓度在线测量技术,研究了乙醇 水混合溶剂中尿苷酸(Uridine 5' monophosphate)质量浓度与溶液密度的关系。20℃条件下,测定了尿苷酸在不同质量分数乙醇 水混合溶剂中的溶解度和溶液密度,以及混合溶剂质量分数一定时的尿苷酸质量浓度和溶液密度。实验结果表明:乙醇 水混合溶剂中,溶液体积与尿苷酸质量浓度具有较高的相关性,可以拟合得到三元溶液体系尿苷酸质量浓度与溶液密度的变化关系式。     

纳他霉素在水和甲醇中溶解度的测定与关联

平衡法测定了纳他霉素在纯水(278.2～341.2 K)、甲醇(278.2～313.2 K)和不同水-甲醇比例混合溶剂（278.2～308.2 K）中的溶解度。采用人工神经网络对纳他霉素在纯水和甲醇中的溶解度数据进行关联,效果令人满意。纳他霉素在不同水-甲醇比例混合溶剂中的溶解度随温度的升高而增加,随水比例的增加而减少。采用非线性最小二乘法将实验数据关联为λh方程的形式,取得较好的效果,其中,λ、h可表达为水-甲醇比例的函数,用于内插计算,精度满足工程需要。实验得到的溶解度数据和关联结果对纳他霉素结晶工艺的研究具有较大的指导意义。     

Solubility of hinokitiol in supercritical fluids; measurement and correlation

Supercritical fluid technology has been an alternative for purification and separation of biological compounds in cosmetic, food, and pharmaceutical products. Solubility information of biological compounds in supercritical fluids is essential for choosing a supercritical fluid processes. The equilibrium solubility of hinokitiol was measured in supercritical carbon dioxide and ethane with a static method in the pressure range from 8 to 40MPa and at temperatures equal to 313.2, 323.2 and 333.2 K. The experimental data were correlated well by Peng-Robinson equation of state and quasi-chemical nonrandom lattice fluid model.     

Transformation of microstructure and phase of disodium guanosine 5′-monophosphate: Thermodynamic perspectives

Microstructure and phase transformation of disodium guanosine 5′-monophosphate (5′-GMPNa₂) are extremely important for controlling the process and understanding the mechanism of crystallization. In this work, the thermodynamic properties of polymorphous 5′-GMPNa₂ especially the solubility were studied, the solubility results show that 5′-GMPNa₂ is more soluble in ethanol–water (E–W) than in isopropanol–water (I–W). The amorphous form of 5′-GMPNa₂ is more soluble than the crystalline form at the same mole fraction and temperature. Meanwhile, the crystalline forms and morphologies of the residual solids were characterized by PXRD and SEM. The results indicate that solid forms of 5′-GMPNa₂ transformed spontaneously from amorphous to crystalline when the ethanol proportion is ≥ 20%. In addition, increasing the pH facilitates the dissolution of 5′-GMPNa₂ and helps to maintain the crystalline form. The associated Gibbs free energy values were calculated to verify the trend of transformation from amorphous to crystalline 5′-GMPNa₂. These results should help to guide the industrial crystallization process and to obtain the crystalline form of 5′-GMPNa₂.     

对乙酰氨基苯甲酸在甲醇+乙醇混合溶剂中溶解度测定及关联计算

溶解度的实验和计算是固-液相平衡热力学研究的基础, 为工业结晶分离过程优化提供重要参数。本文以对乙酰氨基苯甲酸为目标溶质, 在标准压力下, 通过激光动态法在277.95~323.35K温度范围内, 测量其在甲 醇+乙醇混合溶剂中(乙醇质量分数0、20%、40%、60%、80%、100%)的溶解度, 分析了溶解过程中的热力学现象。实验数据用Modified Apelblat、修正的Jouyban-Acree两种热力学模型进行了关联计算。结果表明, 两种模型对对乙酰氨基苯甲酸的关联效果都很好, 其中Modified Apelblat、修正的Jouyban-Acree方程的计算值与实验值的平均相对偏差分别为0.702%和1.105%。通过热力学理论分析, 计算得到对乙酰氨基苯甲酸在混合溶液中溶解焓Δ_dH_m和溶解熵Δ_dS_m, 结果发现该溶解过程为放热过程, 焓变对溶解过程影响较大。     

铬盐液相氧化工艺分离过程中多元体系溶解度的测定及关联

采用平衡分析法,测定了常压下铬铁矿液相氧化生产铬盐工艺分离过程涉及的NaOH-H₂O-Na₂CrO₄、NaOH-H₂O-NaAlO₂、NaOH-H₂O-Na₂SiO₃三元体系,NaOH-H₂O-Na₂CrO₄-Na₂SiO₃、NaOH-H₂O-Na₂CrO₄-NaAlO₂、NaOH-H₂O-Na₂SiO₃-NaAlO₂ 四元体系及NaOH-H₂O-Na₂CrO₄-Na₂SiO₃-NaAlO₂五元体系中Na₂CrO₄、NaAlO₂、Na₂SiO₃的溶解度,并使用Apelblat方程对实验数据进行了回归。实验的温度范围为353.15～403.15 K,除测量Na₂CrO₄在NaOH-H₂O-Na₂CrO₄三元体系中的溶解度时NaOH的浓度从100 g·L^-1改变到 800 g·L^-1,其他体系中都固定NaOH浓度为500 g·L^-1。研究结果表明铝酸钠、硅酸钠无论单独存在还是同时存在均会降低铬酸钠的溶解度,其中铝酸钠对铬酸钠的溶解度影响最大,而硅铝共存反而对铬酸钠溶解度影响最小。     

Solubility of ethylene in 2,2,4-trimethylpentane and 1-octene mixture

With a static type equilibrium cell and the pressure decaying method, the solubility of ethylene in a mixture of 2,2,4-trimethylpentane and 1-octene was measured in the temperature range of 323.15-423.15 K, pressure range of 5-25 bar, and 1-octene concentration from 0 to 85 wt%. The experimental results show that the solubility of ethylene in a 2,2,4-trimethylpentane and 1-octane mixture increases with system pressure but decreases with system temperature.The experimental solubility data were also expressed in the vapor-liquid equilibrium relationship and correlated by the bubble pressure calculation using the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules. Among the deviations between the experimental and correlated results, the largest value of average absolute relative deviation is 1.73% for pressure at 423.15 K and that of average absolute deviation is 0.0024 mol fraction for vapor composition at 373.15 K by the Zhong-Masuoka mixing rule.     

酒石酸钠二水合物的溶解度测定及关联

用动态法测定了酒石酸钠二水合物在不同质量配比的乙醇-水混合溶剂中的溶解度,以期为酒石酸钠二水合物提供结晶热力学数据。结果表明:酒石酸钠二水合物在乙醇-水混合溶剂中的溶解度随水质量分数和温度的增加而增加,但随着水质量分数的增加,升高温度对酒石酸钠溶解度的增加量逐渐变小。采用Modified Apelblat,Van't-JA及Apel-JA方程对溶解度数据进行了关联,均方根偏差最大为6.24×10~(-4)。所选热力学方程均能很好的关联溶解度数据,其中Modified Apelblat方程的关联效果最好。此外,采用Van't Hoff方程计算了酒石酸钠二水合物在乙醇-水混合溶剂中的表观溶解热力学数据,数据表明其溶解过程为非自发的吸热过程。     

Synthesis of barium fluoride nanoparticles by precipitation in ethanol-aqueous mixed solvents

In this work, the BaF₂ nanopowders with different particle size were synthesized by precipitation in the ethanol/water mixed solvents. Five kinds of compositions of mixed solvents, including pure water, 25 vol.%, 50 vol.%, 67.5 vol.%, and 75 vol.% of ethanol were used. The effects of aging and the volume percentage of ethanol in the mixed solvents on the resultant BaF₂ nanoparticles were under investigation. The size and morphology of the BaF₂ particles were characterized by TEM, FSEM and XRD analyses. The results show that after aging for 2 h the particle size of the BaF₂ precipitates in the 50% mixed suspension changes little. The prepared BaF₂ particles all exhibit cubic fluorite structures no matter what kind of composition is used. In pure water environment, the size of BaF₂ particles is about 70 nm, whereas it reduces to 33 nm in the 75% mixed solution. As the vol.% of ethanol increases the particle size decreases, and other properties such as the size distribution, dispersion, oriented growth et al. are also modulated. These alterations can be interpreted by varying the dielectric constant of mixed solvent.     

T型微通道内液滴尺寸的实验测定与关联

利用高速摄像仪对不同深宽比的T型微通道内液滴尺寸进行了实验研究。分别采用3种不同尺寸(深度×宽度)的微通道:400 μm×400 μm、400 μm×600 μm、400 μm×800 μm。以环己烷为分散油相,含0.3%表面活性剂十二烷基硫酸钠(SDS)的蒸馏水-甘油(质量分数分别为20%、40%、60%)溶液为连续相。考察了弹状流、过渡流和滴状流流型下微通道尺寸、两相流率、物性对液滴尺寸的影响。结果表明:液滴尺寸随微通道深宽比、连续相流率、黏度和毛细数的增加而减小,随分散相流率的增加而增加。用毛细数、两相流量比和通道深宽比对微通道内液滴尺寸进行了关联和预测,预测值与实验结果吻合良好。     

BuNENA/DMSO二元体系密度、黏度测定及关联

利用密度瓶和乌氏黏度计分别测定了25,40,50,70℃时BuNENA/DMSO二元体系的密度、黏度,并对黏度与温度、组成的关系进行了多项式回归,模型计算值平均相对误差在0.17%—1.53%。由密度数据计算出超额摩尔体积VmE,由黏度数据计算出不同温度、组成下的超额黏度Δη,其中VEm为正值,Δη为负值。对混合液在不同温度下的VmE与组成的关系用Redlich-Kister方程进行了关联,平均相对误差小于3%。     

The mildiomycin biosynthesis: initial steps for sequential generation of 5-hydroxymethylcytidine 5'-monophosphate and 5-hydroxymethylcytosine in Streptoverticillium rimofaciens ZJU5119

Mildiomycin (MIL) is a peptidyl nucleoside antibiotic with strong activity against powdery mildew disease of plants. We have cloned the MIL biosynthetic gene cluster in Streptoverticillum rimofaciens ZJU5119 and shown that this organism also produces the related antifungal compound, deshydroxymethyl mildiomycin (dHM-MIL). A cosmid genomic library was screened for a putative nucleotide hydrolase gene that is related to blsM from the blasticidin S cluster. Six cosmids were identified that contained a 3.5 kb DNA fragment that harbors a homologue of blsM. The sequence of the fragment revealed two open-reading frames that are likely to function in MIL formation: milA is a CMP hydroxymethylase gene and milB is the homologue of the CMP hydrolase gene blsM. Insertional disruption of milA abolished the production of MIL but not dHM-MIL, whereas a milB knockout strain did not produce either of the peptidyl nucleosides. Recombinant MilA was produced in E. coli and shown to specifically introduce a C-5 hydroxymethyl group on CMP, but it did not accept cytosine or dCMP as a substrate. MilB was also expressed and purified from E. coli and shown to efficiently hydrolyze both hydroxymethyl-CMP (HMCMP) and could accept CMP as an alternative substrate. The ratio of free HMC and cytosine released by MilB was ca. 9:1 in in vitro assays, and is consistent with the higher levels of MIL compared to dHM-MIL that are produced by Streptoverticillum rimofaciens.