An automated, parallel processing approach to biomolecular sample preparation

Sample preparation for DNA and RNA assays is a prime candidate for laboratory automation. A novel, parallel processing device that performs the three separate liquid-handling functions necessary for such sample preparation-dispensing, pipetting, and pressurizing-is presented. The device comprises an array of fine nozzles connected by fluidic channels to automatically and precisely distribute flow between one source and an array of points. The design principles, as well as the experimental and computational methods used to develop the device, are described. Test results, including accuracy, uniformity, volume range, and timing, are presented. The functionality of the device is demonstrated by performing a solid-phase extraction of DNA with two types of microcolumns.     

Small blaze angle gratings with various surface treatments for use in the extreme ultraviolet

Three replica gratings were made from a single master; two were epoxy overcoated with different thicknesses of gold, and one was replicated directly in gold. Their performance in EUV light at grazing incidence angles was measured and compared.     

Inherent limitations in ectomography

Ectomography, a general tomographic method currently being implemented in nuclear medicine, is described. The object is viewed from different directions from the same projection angle, and the reconstruction process can be described as a two-dimensional filtered back-projection technique. One limitation of this limited-angle approach is that a three-dimensional Fourier representation of the acquired projections has a cone where data are missing. This empty cone can cause distortions in the tomogram by insufficient elimination of details outside the reconstructed tomographic section and by distortion of details in the section. The degree of distortion is dependent on the extension of the object in all directions and on the projection angle. Despite these limitations ectomography can be superior to single-photon-emission computed tomography for imaging sections that are close and parallel to the surface of the object, as in imaging of the hip joint or the heart.     

铝电解工须知(5)

六) 打壳经过一定时间就需要打壳的原因我们知道得很清楚。下面列举出这些原因和打壳作业对操作的影响。打壳的原因如下: 1.使氧化铝加入到电解槽中去;     

化妆品的最新组分——脂质体

1963年Bangham首次发现脂质体。到60年代未脂质体被认为是有效的、专门的药物载体,能将其所裹复的药物直接输送到所选择的细胞位置上。尽管早期有相当多有关它的研究文章,然而到1985年年底在市场上仍然没有含有脂质体的产品。 1986年6月在市场上首次出现含有脂质体的产品,但不是药物,而是化妆品。脂质体是人造的圆的微小的胶囊。它由磷脂制成。能将活性组分密封在它的结构