Flow of granules through cylindrical hopper

The gravity flow characteristics of pharmaceutically important granules were studied in a cylindrical hopper with attachable orifice disk at the bottom. Results indicate that materials property and orifice diameter play key role in determining mass flow rate while keeping environmental condition (temperature) at fixed range. A new dimensionally analyzed equation was developed to predict gravity flow of pharmaceutically important granules. The developed correlation agreed well with the experimental data. Calcium gluconate and lactose were used for preparing granules. Generally, glidant/lubricant materials are added to pharmaceutical granules during tablet manufacturing process, in order to improve physical property of granular material. Hence, the effect of glidant/lubricant on mass flow of granules through hopper was also studied. Magnesium stearate (1.5%) was added as glidant before granulation.     

Reply to the Comment by K. Jorgensen et al. to “Analysis of constant rate period of spray drying of slurry”

Previously developed model for spray drying of slurry droplets with high solid content (Liang, 2001) was revised to describe correctly a boundary condition on the outer surface of droplet on basis of the rate of liquid evaporation.     

Coupling granule properties and granulation rates in high-shear granulation

It is possible to link granulation rates to granule properties. The linkage is by multiple dimension population balance equations that, by means of simplifying assumptions, can be reduced to multiple one-dimensional (1-D) population balance equations (PBEs). Using simple physically based models, this paper demonstrates how multiple one-dimensional population balance equations can describe the results of high-shear granulation experiments of two different materials, calcium carbonate and lactose. Good agreement between experimental and simulated results was achieved enabling the granulation rates to be defined by two model parameters: the critical binder volume fraction and the aggregation rate constant. The modelling framework presented in this paper also provides a basis for the kinetic analysis of granulation experiments so that with further work, it is possible to determine the effect of process conditions and material properties on the model parameters.     

屏风固金颗粒对小鼠免疫功能的影响

目的探讨屏风固金颗粒对小鼠免疫功能的影响。方法测定屏风固金颗粒对小鼠脾淋巴细胞增殖、白细胞介素-2(IL-2)、白细胞介素-1(IL-1)及NK细胞活性的影响。结果屏风固金颗粒组对上述免疫指标的作用与对照组比较均有显著性差异,与玉屏风颗粒组比较也显著增强。结论屏风固金颗粒能够诱导小鼠脾细胞淋巴细胞增殖,刺激IL-2、IL-1的分泌及NK细胞的活性,具有免疫增强作用。     

Comparative analysis of starch properties of different root and tuber crops of Sri Lanka

The physicochemical properties of starches of six different root and tuber crop species grown mainly in Sri Lanka showed significant differences among the tested crop species and varieties. The median granule size of starch of tested root and tuber crop species varied from 33.5 to 10.2 μm. The largest granule size and the highest blue value were given by the canna, Buthsarana, and yam species, in that order. The amylose content of cassava was higher than those of sweet potato and many yams. High peak viscosities, high breakdown, and high final viscosities were observed in yams, and, generally, such starch showed a high swelling power. According to the correlation analysis, these pasting properties would mainly be due to their larger starch granule size. Based on the thermal properties, cassava starch showed less energy requirement for gelatinization and thus gelatinized at lower temperatures. Furthermore, a higher susceptibility of raw cassava starch toward fungal glucoamylase was observed. The low enzyme digestibility of raw yam starch would be due to its large granules. Correlation analysis showed that the blue value and starch granule size were important in determining the pasting, thermal, and other properties of starch.     

黄芪颗粒中总黄酮的含量测定

建立了黄芪颗粒中总黄酮的含量测定方法:以芦丁为参照,利用紫外分光光度法在371 nm波长测定黄芪颗粒中总黄酮的含量。芦丁在5.90～59.0μg/mL线性关系良好,线性方程为A=0.0103C+0.2707,γ=0.9963,平均回收率为98.65%,RSD%=0.85%。结果表明:紫外分光光度法测定黄芪颗粒中总黄酮的含量方法简便,快捷,准确,可用来做黄芪颗粒的质量评估的方法。     

涡流分级机的分级轮研究

在分级系统中,分级轮对于物料的分散、分级起着非常重要的作用。通过分析气体在分级轮中所受的作用力,推导出分级粒径公式,并得出分级轮的风量、转速与分级粒度及分级精度的关系。     

粒料重力掺混性能研究

介绍了物料在料仓中的流动状态和掺混机理。通过测量物料的掺混数据,结合影像资料,分析出大颗粒物料掺混中离析的另一原因是质量小的物体在碰撞后的速度大于质量大的物体;掺混时间(循环次数)要根据物料情况而定,时间太长有可能发生物料离析;料仓进料口距料面的距离要尽量小,以降低碰撞的初速度。     

Foam granulation: Liquid penetration or mechanical dispersion?

There have been significant advances in the understanding of wet granulation processes. Foam granulation is the latest development and an emerging area of interest for pharmaceutical manufacturing.Single foam penetration experiments were carried out on static powder beds, followed by short-nucleation experiments (where nuclei are formed by a nucleation-only mechanism) and full foam granulation experiments (where nucleation, growth and breakage are occurring simultaneously). All experiments were performed with lactose monohydrate powder using a 5 L high shear mixer–granulator. The foam penetration/dispersion behaviour was examined and the granule size distributions were investigated as a function of foam quality (83–97% FQ), impeller speed (105–515 rpm) and wet massing period (0–4 min).Nucleation in foam granulation is postulated to undergo either “foam drainage” or “mechanical dispersion” controlled mechanisms. For “foam drainage” mechanism, the foam penetrates the powder bed to form coarse and broad granule size distributions. For “mechanical dispersion” mechanism, the wetting and nucleation conditions are governed by the powder mixing conditions and similar granule size distributions are produced. Regardless of the mechanism, the initial wetting and nucleation behaviour controls the initial nuclei size distribution, and this initial distribution is retained in the final granule size distribution. This work demonstrated the critical importance of the nucleation and binder distribution in determining the granule size distributions for foam granulation process.     

Role of mass transfer in overall substrate removal rate in a sequential aerobic sludge blanket reactor treating a non-inhibitory substrate

A laboratory study was undertaken to explore the role of mass transfer in overall substrate removal rate and the subsequent kinetic behavior in a glucose-fed sequential aerobic sludge blanket (SASB) reactor. At the organic loading rates (OLRs) of 2-8 kg chemical oxygen demand (COD)/m³-d, the SASB reactor removed over 98% of COD from wastewater. With an increase in OLR, the average granule diameter (d_p = 1.1-1.9 mm) and the specific oxygen utilization rate increased; whereas biomass density of granules and solids retention time decreased (13-32 d). The intrinsic and apparent kinetic parameters were evaluated using break-up and intact granules, respectively. The calculated COD removal efficiencies using the kinetic model (incorporating intrinsic kinetics) and empirical model (incorporating apparent kinetics) agreed well with the experimental results, implying that both models can properly describe the overall substrate removal rate in the SASB reactor. By applying the validated kinetic model, the calculated mass transfer parameter values and the simulated substrate concentration profiles in the granule showed that the overall substrate removal rate is intra-granular diffusion controlled. By varying different d_p within a range of 0.1-3.5 mm, the simulated COD removal efficiencies disclosed that the optimal granular size could be no greater than 2.5 mm.