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.     

矿产资源形势分析与预测的理论与方法

结合矿产资源形势分析与预测的基本理论，综合介绍了目前比较流行的几种分析与预测的方法，旨在为政府和企业提供预测方法和决策依据，以促进资源的合理开发和利用。     

甘肃敦煌雅丹国家地质公园总体规划

总体规划充分尊重地质演化的自然特征和属性,综合科普教育和旅游观光的要求,进行合理布局.对于未来公园建设中可能出现的不利因素也进行了分析,并提出对策.对于如何发展敦煌的区域旅游提出了合理的建议.     

两个"住"的实验

本文介绍了笔者参与的两个关于中国住宅竞赛的实验……希望引发设计者重新思考众多因素对居住的影响。"     

"三缺一"情境下的空间演绎与营造——广州图书馆新馆设计竞赛评析

本文简要介绍了广州图书馆新馆设计国际邀请竞赛的背景和概况,分析了项目基地的特殊空间情境,从建筑体量的呼应、空间形态的协调、图书馆文化特性的缔造等几个方面,对竞赛方案的空间环境演绎与营造进行评析,探讨了相应的设计方法和策略,以期对国内类似的工程建设提供参考。     

以美国景观设计市场化经营为鉴,审视中国的发展

加利福尼亚作为美国自然环境多样化和文化多元的地区,景观设计在历史上形成了独具特色的风格.在二战以后社会变革和产业复兴中,景观设计学在私营领域得到了巨大发展,涌现了大量的事务所.通过介绍笔者在加州的实践二例,并从多学科合作的设计方法、与不同主体的沟通策略、发展开放空间以及城市复兴的经济和社会考虑等多个方面,阐述了景观设计的意义,并强调私营部门的积极作用,以期对中国的景观设计学发展有所助益.     

舟山桃花岛桃花湾景观旅游规划探析

近些年大量游客涌入以及由此引出的各种服务设施建设造成了风景区自然景观严重的破坏，使风景区内原定的自然审美功能严重丧失。以浙江舟山群岛桃花岛桃花湾景观旅游规划为例，探析风景区规划新思路。在对舟山桃花湾现状和景观资源进行的科学分析基础上，规划着重探讨了旅游度假风景区的规划布局以及沿海沙滩景观的保护和利用，力求达到规划的生态效益、经济效益、人文效益和社会效益的统一。     

黄山风景名胜区分区规划研究

分区规划作为协调保护和利用关系的重要手段,是风景名胜区总体规划中的核心内容。以黄山风景名胜区为例,介绍了现状多种分区并存的局面和分区之间的结构,分析了现状分区规划及其实施中存在的问题,再从分区类型、管理政策等方面提出规划改进意见,包括将分区细分为四大类十小类,以及针对具体的人类活动、人工设施和土地利用类型分别制定管理政策,最后提出分区监测的概念,并对监测指标和标准的选择进行了初步探讨。     

华南植物园总体规划

根据本次规划的指导思想和基本理念,对规划区进行了植物园体系规划和园区景观规划,以实现科研、科普、生产、景观四位-体共同发展模式,并对本次规划的预期效果进行了分析和评价.