The control of paracetamol particle size and surface morphology through crystallisation in a spray dryer

The parameters governing the crystallisation of paracetamol using various conventional techniques has been extensively studied, however the factors influencing the drug crystallisation using spray drying is not as well understood. The aim of this work was to investigate the crystallisation of an active pharmaceutical ingredient through evaporative crystallisation using a spray dryer to study the physicochemical properties of the drug and to use semi-empirical equations to gain insight into the morphology and particle size of the dried powder. Paracetamol solutions were spray dried at various inlet temperatures ranging from 60 °C to 120 °C and also from a series of inlet feed solvent compositions ranging from 50/50% v/v ethanol/water to 100% ethanol and solid-state characterisation was done. The size and morphology of the dried materials were altered with a change in spray drying parameters, with an increase in inlet temperature leading to an increase in particle Sauter mean diameter (from 3.0 to 4.4 µm) and a decrease in the particle size with an increase in ethanol concentration in the feed (from 4.6 to 4.4 µm) as a result of changes in particle density and atomised droplet size. The morphology of the dried particles consisted of agglomerates of individual crystallites bound together into larger semi-spherical agglomerates with a higher tendency for particles having crystalline ridges to form at higher ethanol concentrations of the feed.     

Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.     

Coupled field formulation of exactly integrated membrane finite elements insensitive to distortion

Abstract

An efficient 4-noded membrane element tolerant and insensitive to mesh distortion is developed using kinematically coupling the in-plane displacements which satisfy the equilibrium equations in Cartesian coordinates and results in material-dependent coupled field interpolation functions making the element free from volumetric and shear locking. The proposed formulation provides a preliminary concept for the satisfaction of natural boundary conditions which is used to satisfy the strong patch test. The proposed element, passed several benchmark problems from the literature, compared well with elasticity solutions, passed the weak patch test and the inf-sup test for both compressible and incompressible cases.     

某新生代红土型金矿选矿试验研究

针对云南某新生代红土型露天金矿金的粒度分布呈粗细极不均匀的特点,采用高离心力场重选工艺进行研究,较好地解决了粗粒金以及微细粒金的回收难题,当原矿金品位1.1g/t,精矿金品位47.23g/t,金回收率达到86.09%,获得了满意的选别指标。     

发电厂温度检测仪表选型

合理选择仪表 ,是经济与科学技术正确结合的综合性工作 ,结合电厂实际应用情况 ,重点介绍一般温度检测仪表的选型。     

对依兰煤田钻孔缩径挤夹钻具事故的认识

针对依兰煤田钻探施工中出现的钻孔缩径挤夹钻具事故,提出产生事故的根本原因不是因岩层本身膨胀所致,而是由于某种岩层裂隙发育,渗透性良好,吸水性强,使钻孔孔壁泥皮迅速增厚所致,并提出预防事故的具体措施。     

冻土钻孔内的温度分布——冻土钻探专题之一

分析了冻土钻孔中温度分布的意义 ,提出了孔内温度的数学模型 ,计算了钻头破碎岩石产生的温度增量 ,指出了防止钻孔坍塌的条件     

大功率全数字磁场换向直流调速系统中应注意的问题

通过介绍磁场换向原理,使用MATLAB仿真并结合现场实际的数据,讨论了全数字磁场换向直流调速系统中应注意的一些问题。     

Effect of temperature on nitinol electropolishing

1IntroductionIn recent years,the study of surface preparation has attracted considerable attention due to its poten-tiallyi mportant effect on properties of Ni Ti medical components.Amongthose surface treat ment methods,electropolishing has attracted a great attention for its distinctive advantages.Electropolishing removesslag,burrs,scratches,heat affected zones and creates a new,smoother surface.The polishing rate can becarefully adjusted within tight tolerances to meet different requirement…     

DS18B20在温度控制中的应用

介绍了单线数字温度传感器DS1 8B2 0的结构、特点、工作原理 ,设计了一种基于DS1 8B2 0的数字自动化温度控制装置。给出了装置的结构及DS1 8B2 0的C5 1程序