拉斯研究小组

拉斯调研组:古代的油漆和危险的爆炸物检测的化学/生物研究

我的研究主要集中于两个项目:(1)史前岩石颜料的化学分析。和(2)的方法来在距离检测爆炸物。起初这些似乎截然相反,但实际上都需要使用复杂的,国家的最先进的化学仪器。

在得克萨斯州的下佩科斯区古涂料的化学/生物研究

对于7000多里,人类居住的区域与周围的格兰德河佩科斯和鬼子河流汇合处(查看地图)。千百年前的阿纳萨齐开始留下痕迹在四个角区域,最早的德州开始生产的艺术画作壮观,在某些情况下,完全覆盖大,干燥岩石掩体后面的墙壁一个令人难以置信的丰富。 4000年以前 - 根据放射性碳分析和文体的解释,绝大多数的岩画是3000之间产生。这以周期升高的人类群体的,从而在制造岩石技术的可能连接于不同的文化现象相一致。换句话说,绘画的创作很可能是自然的应力,这是人类独有的响应。 [插图:地图指示所述研究领域]

Our research uses state-of-the-art analytical methods to probe the mysteries of the art by understanding the chemistry of the ancient paints. Specifically, we want to know what substances were used to prepare the paints, how various paintings or motifs are related based on chemical similarities, and how the ancient paints remain intact on the  rock substrate. The most compelling question in the study of prehistoric rock paints is the nature of the vehicle/binder, i.e., fats or oils added to inorganic pigments to create a fluid paint that adheres to the rock surface. Our most recent study used gas chromatography-mass spectrometry (GC-MS), which led us to conclude that the only fats or oils that remain in the paints today are not from the original paint recipe, but instead from microbes that are growing on the rock surface (Spades & Russ, 2005). [Photo: The "Ghost Shaman" in Fate Bell Shelter]

Another study was aimed at identifying the organisms that occur naturally the rock surfaces, and how these microbes impact the preservation of the rock art.  Although most of the paintings appear clear to the naked eye, in actuality the paint layers are encased within a natural rock coating composed almost entirely of calcium oxalate.  This is easily observed in the photograph here, a side-view of a thin-sectioned sample of paint.  Our results demonstrate the there are numerous strains of bacteria growing on the rock surfaces, mostly the species Bacillus. Moreover, these microbes produce calcium oxalate, at least in culture media. Thus, that these artifacts remain intact for thousands of years is not due to characteristics of the paints, per se, but from natural bacterial producing a mineral accretion that keeps the paints attached to the rock substrate (Hess, Coker, Loutsch & Russ, 2007). [Photo: Side view of tpical paint sample]

对峙爆炸性危险检测系统(阴影)

简易爆炸装置(IED)在伊拉克伤亡的n个棕土原因之一。我们的研究,由美国资助国防部,旨在开发迅速在环境中距离检测爆炸物如伊拉克街头的新系统。这场对峙爆炸性危险检测系统(色调)是由一个团队在阿肯色州立大学的科学家和工程师的开发, 辐射技术,并在这里罗德。我们的组集中于三个相互关联的研究:(1)样品收集,(2)浓缩爆炸化合物,和(3)检测目标化合物。 

样品采集

我们的主要目标之一是开发一种空气收集器,其在注射之前消除灰尘,污物和沙子进入非常敏感的色调检测器。我们测试各种虚拟撞击到我们从空气传播的微粒物质检测目标化合物分离,而前者被注入检测器系统中的后者是从装置排出。

浓缩爆炸性化合物

一旦空气样品通过虚拟冲击“干净的”,下一步是提取并检测爆炸物。我们采用固相微萃取(spmes)同时收集和浓缩炸药分子进行最终分析。在SPME由具有各种类别的化合物具有亲和性的小的聚合物纤维,在我们的情况下,我们使用的是2,4-二硝基甲苯(DNT)作为我们的首要目标分析物,因为这是TNT的主要降解产物(2,4,6- 6三硝基甲苯)。

检测目标化合物的

我们的组使用气相色谱电子捕获检测器(GC-ECD)来检测爆炸物的化合物。我们与各种仪器参数,spmes和阀门系统,使我们能够最小化,我们能够检测样品的量进行试验。左边是一个单一的实验,其中,经由峰观察到在色谱图上的右侧的目标化合物(2,4- DNT)的存在下的典型的结果(色谱图)。此峰是分析暴露于目标化合物五秒钟特定SPME的结果。