Studies of elemental distributions within discrete coal macerals: Use of secondary ion mass spectrometry and X-ray photoelectron spectroscopy

Secondary ion mass spectrometry has been used to measure qualitatively the distributions of many trace and minor elements within some well-characterized coal macerals: vitrinite, fusinite and exinite. Complementary information was obtained by using X-ray photoelectron spectroscopy. Within the vitrinite specimens studied, a widely-dispersed largely inorganic aluminosilicate phase was identified, which contained a number of other trace elements. By contrast, within the organic-rich phase of this macerai, titanium was detected in a very even distribution; this suggests that some titanium may be bonded in an organic complex. The fusinite was shown to contain elevated concentrations of calcium, magnesium and fluorine, dispersed over a large portion of the maceral. The high fluorine content could be identified as an organo-fluoro compound using XPS. Exinite was found to contain lower concentrations of most elements, compared to other macerals. The organic composition of this maceral was significantly different from that of surrounding macerals; this could be seen from the enhanced emission of the C₂H₂-secondary ion and images of this ion thus clearly outlined the position of such macerals.     

A computational framework for representing authors'' courseware models*

Abstract This paper looks at some of the problems of existing courseware authoring systems, and advocates the use of knowledge-based techniques to resolve these problems and to form the basis of future authoring environments. The prototype knowledge-based representation language, GTE, is presented as an example of a knowledge-based language which might form the basis of such environments. The final part of the paper discusses some of the developments in GTE which must take place if it is to be used within a full and flexible authoring environment. The paper will focus particularly on the question of instructional strategies, but many of the observations can be taken as relevant to all the knowledge involved in a teaching interaction.     

拉丁美洲非织造布行业持续增长

虽然拉丁美洲经济波动较大,但该地区的非织造布行业持续增长。增幅已超过主要经济体的国内生产总值。随着一次性卫生用品不断在消费者中普及和渗透,拉美地区对非织造布的投资将会继续增加。     

气流成网技术的重生

20年前,气流成网技术在北美地区迅速扩张,导致了很长一段时间的产能过剩.如今,随着新企业进入市场,并使用该技术开发新产品,使气流成网技术获得重生.新设备、新技术以及新的生产商"各显神通",为气流成网技术创造新机遇,设备制造专家正通过研发新技术,实现产品工艺类型、纤维种类和尺寸方面的多样化选择,使潜在客户真正获得他们需要...     

埃克森美孚公司应对新冠肺炎危机

自1965年埃克森美孚公司的研究机构建立了第一条熔喷试产线以来,聚丙烯一直是这一领域的标杆性原料.在过去几个月中,由于需求的增加,大量的新熔喷线涌入市场,这将推动全球对该材料的需求. 为应对这一需求,埃克森美孚公司在2020年4月宣布,将增加生产口罩、防护服和消毒剂的关键原料,助力医护和相关人士应对全球新冠肺炎疫情.举...     

利用降压转换器为便携设备供电

PDA及笔记本电脑等便携式产品若采用锂电池为其微处理器供电,在一般情况下都会采用小型而又具能源效益的降压直流-直流转换器。若以转换效率作为衡量标准,开关稳压器才是佳的选择。若元件高度受到限制,便不能使用电感(移动电话等便携设备常受此限制)。在这种情况下,采用低压降(LDO)线性稳压器作为转换器可能是一个较为理想的选择。只要微处理器电压接近电池电压,外型小巧且成本低廉的低压降芯片便可发挥其最高的效率。若电压差距太大,低压降芯片的效率便会大打折扣。     

世界水刺产品市场发展情况

近几年来．水刺市场一直围绕纸巾发展。随着纸巾在全球范围内变得越来越普及．非织造布生产商纷纷投资于水刺技术．希望在庞大市场上分得一杯羹。然而，最近．纸巾市场发展趋缓．新生产能力的增加导致了价格竞争。     

卫生用品纤维生产商报告:满足行业对绿色材料的需求

卫生用品行业一直面临着安全性、产品功效与可持续性之间维持平衡的挑战,随着新的纤维和原料不断出现,上游非织造布生产商和用户正在努力应对新常态.多年来他们一直希望通过生产对地球更友好的产品来提高产品的可持续性,现在许多人正想方设法确保产品能保护使用者的健康和安全,免受新冠肺炎病毒的侵害.     

卫生用品原材料的持续创新

埃克森美孚推出热熔胶新材料 埃克森美孚化工公司以专有茂金属技术,开发了新一代的低粘度弹性体聚合物,型号为8780和8380,用于卫生用品生产中使用的热熔胶。新的弹性体拓宽72015年市场上销售的型号为8880弹性体在胶粘剂中的应用范围。这三种产品能够使热熔胶实现低气味、低密度、颜色浅等性能,应用于包装、卫生用品和装配领域中。