Journal of Research of the National Institute of Standards and Technology最新文献

In the last two decades, the microfluidics/lab-on-a-chip field has evolved from the concept of micro total analysis systems, where systems with integrated pretreatment and analysis of chemicals were envisioned, to what is known today as lab-on-a-chip, which is expected to be modular. This field has shown great potential for the development of technologies that can make, and to some extent are making, a big difference in areas such as in vitro diagnostics, point of care testing, organ on a chip, and many more. Microfluidics plays an essential role in these systems, and determining the standards needed in this area is critical for enabling new markets and products, and to advance research and development. Our goal was to bring together stakeholders from industry, academia, and government to discuss and define the needs within the field for the development of standards. This publication contains a summary of the workshop, abstracts from each presentation, and a summary of the breakout sessions from the National Institute of Standards and Technology Workshop on Standards for Microfluidics, held on June 1-2, 2017. The workshop was attended by 46 persons from 26 organizations and 11 countries. This was a unique and exciting opportunity for stakeholders from all over the world to join in the discussion of future developments towards standardization in the microfluidics arena.

The CD4 glycoprotein is a component of the T cell receptor complex which plays an important role in the human immune response. This manuscript describes the measurement and modeling of the binding of fluorescently labeled anti-human CD4 monoclonal antibodies (mAb; SK3 clone) to CD4 receptors on the surface of human peripheral blood mononuclear cells (PBMC). CD4 mAb fluorescein isothiocyanate (FITC) and CD4 mAb allophycoerythrin (APC) conjugates were obtained from commercial sources. Four binding conditions were performed, each with the same PBMC sample and different CD4 mAb conjugate. Each binding condition consisted of the PBMC sample incubated for 30 min in labeling solutions containing progressively larger concentrations of the CD4 mAb-label conjugate. After the incubation period, the cells were re-suspended in PBS-based buffer and analyzed using a flow cytometer to measure the mean fluorescence intensity (MFI) of the labeled cell populations. A model was developed to estimate the equilibrium concentration of bound CD4 mAb-label conjugates to CD4 receptors on PBMC. A set of parameters was obtained from the best fit of the model to the measured MFI data and the known number of CD4 receptors on PBMC surface. Divalent and monovalent binding had to be invoked for the APC and FITC CD4 mAb conjugates, respectively. This suggests that the mAb binding depends on the size of the label, which has significant implications for quantitative flow cytometry. The study supports the National Institute of Standards and Technology program to develop quantitative flow cytometry measurements.

We discuss how the impending redefinition of the SI system of units might affect the ability of students to understand the link between the units and the new system. The redefinition will no longer define a set of base units, but rather a set of constants of nature, such as the elementary charge, e. We point out that this list of constants need not be the only way to introduce students to the subject, either in class or in textbooks. We suggest an alternative way to introduce high school and undergraduate students to the redefined SI, by suggesting a list of experiments for some units; this list would be completely compatible with the redefined SI, and would have all of the same scientific and technological advantages. We demonstrate by questionnaire results that this alternative is more appealing to students. We hope to spur a discussion amongst teachers regarding this important topic for high school and undergraduate physics courses.