Search for: All records

This work seeks to explore the capabilities of stationary phase gradients (SPGs) for the large-molecule chromatographic separations of proteins and peptides through a combination of experimental studies and simulations. Continuous SPGs are fabricated on commercial Phenomenex Jupiter C4 columns using the time-based infusion of trifluoroacetic acid through the column. The resultant gradients are characterized using smallmolecule chromatography and physical gradient profiling via thermogravimetric analysis. The gradient columns are then tested using two different protein analyte mixtures and a peptide standard analyte mixture to examine the efficacy of the separations. Collected experimental data from these tests are used to establish fitted parameters for the Linear Solvent Strength (LSS) model to computationally predict the retention behavior of the analytes on the gradient columns. Successful chromatographic separation of all three analyte mixtures was achieved. The re-parameterized LSS model successfully simulates the analyte retention on the gradient columns with only minor deviations from observed experimental retention data. Collectively, this work demonstrates the ability to create a C4 continuous stationary phase gradient starting with a uniform commercial column that can be effectively used to separate mixtures of biomolecules, and the ability to accurately simulate and predict retention times. The computational model described herein could be used to effectively predict retention behavior in silico, significantly reducing the time needed for experimental design. 

Abstract CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r , in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5 σ , or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL.