A5026201606- Nanopore and Nanochannel Transport Studies
- Force Microscopy Techniques and Applications
- DNA and Nucleic Acid Chemistry
- Lipid Membrane Structure and Behavior
- Advanced biosensing and bioanalysis techniques
- Mechanical and Optical Resonators
- Electrostatics and Colloid Interactions
- Photoreceptor and optogenetics research
- Bacteriophages and microbial interactions
- RNA and protein synthesis mechanisms
- Microfluidic and Bio-sensing Technologies
- Radiation Detection and Scintillator Technologies
- Neuroscience and Neural Engineering
- Astrophysics and Cosmic Phenomena
- Radioactive contamination and transfer
- Molecular Junctions and Nanostructures
- Microfluidic and Capillary Electrophoresis Applications
- Radioactive Decay and Measurement Techniques
- RNA Research and Splicing
- Atomic and Subatomic Physics Research
- Spectroscopy and Quantum Chemical Studies
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Medical Imaging Techniques and Applications
National Institute of Standards and Technology
2019-2024
University of Colorado Boulder
2019-2024
University of California, Santa Barbara
2013-2021
University of Pennsylvania
2011-2013
We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz 218 made by the Atacama Cosmology Telescope (ACT) in three seasons of observations 2008 to 2010. A model primary secondary foreground is fit map power spectra lensing deflection spectrum, including contributions both thermal Sunyaev-Zeldovich (tSZ) effect kinematic (kSZ) effect, Poisson correlated anisotropy unresolved infrared sources, radio correlation between tSZ...
Significance Charged, flexible polymers, such as single-stranded nucleic acids (ssNAs), are ubiquitous in biology and technology. Quantitative description of their solution conformation has remained elusive due to the competing effects polymer configurational freedom salt-screened electrostatic repulsion between monomers. We investigate this by measuring elastic response single ssNA molecules over a range salt concentrations. The data well described model, inspired mean-field approach, which...
Xenon and radon have many similar properties, a difference being that all 35 isotopes of ( 195 Rn– 229 Rn) are radioactive. Radon is pervasive indoor air pollutant believed to cause significant incidence lung cancer in geographic regions, yet affinity for discrete molecular species has never been determined. By comparison, the chemistry xenon widely studied applied science technology. Here, both noble gases were found bind with exceptional tris-(triazole ethylamine) cryptophane, previously...
Nucleic acids are strongly negatively charged, and thus electrostatic interactions-screened by ions in solution-play an important role governing their ability to fold participate biomolecular interactions. The negative charge creates a region, known as the ion atmosphere, which cation anion concentrations perturbed from bulk values. Ion counting experiments quantify atmosphere measuring preferential interaction coefficient: net total number of excess above, or below, expected due...
To form secondary structure, nucleic acids (NAs) must overcome electrostatic strand–strand repulsion, which is moderated by the surrounding atmosphere of screening ions. The free energy NA folding therefore depends on interactions this ion with both folded and unfolded states. We quantify such using preferential interaction coefficient or excess: number ions present near in excess bulk concentration. folded, double-helical state has been extensively studied; however, much less known about...
Ligand-induced conformational changes are critical to the function of many membrane proteins and arise from numerous intramolecular interactions. In photocycle model protein bacteriorhodopsin (bR), absorption a photon by retinal triggers cascade that results in pumping proton across cell membrane. While decades spectroscopy structural studies have probed this intricate detail, energetics underlie motions remained elusive experimental quantification. Here, we measured these on millisecond...
We quantified the equilibrium (un)folding free energy ΔG_{0} of an eight-amino-acid region starting from fully folded state model membrane-protein bacteriorhodopsin using single-molecule force spectroscopy. Analysis and nonequilibrium data yielded consistent, high-precision determinations via multiple techniques (force-dependent kinetics, Crooks fluctuation theorem, inverse Boltzmann analysis). also deduced full 1D projection free-energy landscape in this region. Importantly, was determined...
Significance Membrane proteins are of great biological and biomedical interest; they constitute 30% encoded the targets ∼50% drugs. Measurements membrane protein energetics by mutating individual amino acids provide information that cannot be obtained from structural studies alone. Traditional thermodynamic assays employ chemical denaturants nonnative micelles imperfectly reflect biologically relevant conditions native lipid bilayer. Additionally, denaturation is not thermodynamically...
Many chemical techniques exist for measuring the stoichiometry of ligand binding to a macromolecule; however, these are often specific certain ligands or require presumption models. Here, we further develop previously reported, general, thermodynamic method extracting change in number bound macromolecule as that undergoes conformational transition driven by mechanical stretching, example, magnetic tweezers optical trapping. We extend theory this consider systems with many ligands,...
Equilibrium free-energy-landscape parameters governing biomolecular folding can be determined from nonequilibrium force-induced unfolding by measuring the rates $k$ for transitioning back and forth between states as a function of force F. However, bias in observed forward reverse is introduced limited effective temporal resolution, which includes mechanical response time probe any smoothing used to improve signal-to-noise ratio. Here we use simulations characterize this bias, most prevalent...
Single-molecule manipulation instruments have unparalleled abilities to interrogate the structure and elasticity of single biomolecules. Key insights are derived by measuring system response in varying solution conditions; yet, typical control strategies require imposing a direct fluid flow on measured biomolecule that perturbs high-sensitivity measurement and/or removes interacting molecules advection. An alternate approach is fabricate devices permit changes diffusion introduced species...
The conformations of biological polyelectrolytes (PEs), such as polysaccharides, proteins, and nucleic acids, affect how they behave interact with other biomolecules. Relative to neutral polymers, PEs in solution are more locally rigid due intrachain electrostatic repulsion, the magnitude which depends on concentration added salt. This is typically quantified using Odijk-Skolnick-Fixman (OSF) electrostatic-stiffening model, salt-dependent Debye-H\"uckel (DH) screening modulates repulsion....
High spatial and temporal resolution magnetic tweezers experiments allow for the direct calibration of pulling forces applied to short biomolecules. In one class experiments, a force is structured RNA or protein induce an unfolding transition; when maintained at particular values, molecule can exhibit conformational switching between folded unfolded states intermediate states. Here, we analyze degree which common approaches, involving fitting model functions Allan variance power spectral...