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.     

综放开采最大导水裂隙带高度的应力法预测

在重点模拟大采高条件下覆岩低抗拉特性的基础上，建立了“大采高ＦＥＭ－ＮＴＡ耦合模型”．选择了合适的屈服准则、流动法则及应力应变本构关系，综合优选输入参数，于淮南矿务局新集矿实施了该“耦合模型”．预测裂采比为１０．６０～１０．８５倍．经钻探验证，取得了较为理想的预测精度．     

凡口铅锌矿选矿厂生产技术改造

凡口铅锌矿生产技术改造，主要立足企业内部，以提高经济效益为中心，充分利用现有设施，挖掘内部潜力，提高设备利用率，采用新技术、新设备，使选矿厂生产能力从3000t/d扩大到4500t/d，生产能力扩大50%而吨矿电耗、选矿成本明显下降，创造出显著的经济效益和社会效益。     

以“新发展理念”引领地勘行业持续健康发展

"十二五"以来,地勘行业在服务和支撑经济社会发展中的地位与作用越发凸显。"十三五"时期是全面建成小康社会的决胜时期,地勘行业面临一系列的机遇与挑战。本文在总结"十二五"地勘行业发展成效的基础上,深入分析全面建成小康社会决胜阶段地勘行业面临的新形势、新要求,提出以创新发展激发地勘行业发展新动力、形成地勘行业发展协调新格局、探索地勘行业绿色发展新模式、开拓地勘行业开放发展新空间、最终共享地勘行业发展新成果的建议。     

引水冲污工程流量的分析与确定

通过对福州市近年来实施的引水冲污工程中有关引水流量的问题进行了分析,并提出了确定引水流量的方法。     

Decomposing regional productivity growth using an aggregate production frontier

The main contribution of this paper is the implementation of a new model which combines the two parametric approaches most commonly used in the productivity literature: fixed effects and stochastic frontiers. This allows us to discuss whether it is better to use average or frontier functions to estimate regional productivity. The empirical section uses panel data of Spanish regions over the period 1980–1995. Additionally, we calculate and decompose total factor productivity growth for the Spanish regions.     

中国现代建筑理论的解困：五谈引进外国建筑理论的经验教训

该文在回顾了中国现代建筑理论的发展史,并分析了当代中国建筑理论界的现状后,指出：应当把对建筑的引进和研究从外学科和边缘学科拉回建筑本身,以确立建筑在现代科技的支持下,为解决现代社会 服务的目标。     

理想的坚持者,ONL

何为ONL,谁是ONL,ONL为何成为今天的ONL?怀着对其艺术气质的欣赏,对其设计理念的支持,对其工作方式的理解和对其执着追求的精神的钦佩,从个人角度出发对ONL进行速写。     

福州市某泵站运行情况及改进探讨

本文以福州市某泵站为例,针对普遍存在提升后的污水出现回流及运行中频繁出现电缆疲劳断裂,水泵机械密封弹簧因杂物缠绕导致油室泄漏现象,探讨该城市污水提升泵站格栅间距的选择,提出了泵站内出水管改重力流明渠布置为压力管布置形式的设计改进建议。