A5059445446- Lipid Membrane Structure and Behavior
- Surfactants and Colloidal Systems
- Spectroscopy and Quantum Chemical Studies
- Material Dynamics and Properties
- NMR spectroscopy and applications
- Force Microscopy Techniques and Applications
- Electrostatics and Colloid Interactions
- Nuclear Physics and Applications
- Protein Structure and Dynamics
- Thermodynamic properties of mixtures
- Nanopore and Nanochannel Transport Studies
- Phase Equilibria and Thermodynamics
- Liquid Crystal Research Advancements
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Advanced Polymer Synthesis and Characterization
- Advanced Physical and Chemical Molecular Interactions
- Ionic liquids properties and applications
- Polymer Nanocomposites and Properties
- Pickering emulsions and particle stabilization
- Polymer crystallization and properties
- X-ray Diffraction in Crystallography
- Quantum, superfluid, helium dynamics
- Theoretical and Computational Physics
- Hydrogels: synthesis, properties, applications
NIST Center for Neutron Research
2016-2025
National Institute of Standards and Technology
2016-2025
University of Maryland, College Park
2021-2025
University of Delaware
2020-2025
Indiana University Bloomington
2012-2021
National Institute of Standards
2008-2021
Institut Laue-Langevin
2020
University of Tennessee at Knoxville
2020
Clemson University
2020
Bloomington Health Foundation
2019
Significance Cholesterol regulates critical cell functions, including lysis, viral budding, and antibiotic resistance, by modifying the bending rigidity of membranes; i.e., ability membranes to bend or withstand mechanical stresses. A molecular-level understanding these functions requires knowledge how cholesterol modifies membrane mechanics over relevant length time scales. Currently, it is widely accepted that has no effect on properties unsaturated lipid membranes, implying viruses, for...
Monoclonal antibodies (mAbs) are a major class of biopharmaceuticals. It is hypothesized that some concentrated mAb solutions exhibit formation solution phase consisting reversibly self-associated aggregates (or reversible clusters), which speculated to be responsible for their distinct properties. Here, we report direct observation clusters in mAbs using neutron spin echo. Specifically, stable studied across transition from dispersed monomers dilute clustered states at more conditions,...
We have investigated structure and relaxation phenomena for ionic liquids 1-octyl-3-methylimidazolium hexafluorophosphate (C8mimPF6) bis(trifluoromethylsulfonyl)imide (C8mimTFSI) by means of neutron diffraction spin echo (NSE) techniques. The patterns show two distinct peaks appeared at scattering vectors Q 0.3 1.0 Å(-1). former originates from the nanoscale characteristic to latter due interionic correlations. Interestingly, intensity low-Q peak drastically grows upon cooling keeps growing...
The elastic and viscous properties of self-assembled amphiphilic membranes dictate the intricate hierarchy their structure dynamics ranging from diffusion individual molecules to large-scale deformation membrane. We previously demonstrated that neutron spin echo spectroscopy measurements model can access naturally occurring submicrosecond membrane motions, such as bending thickness fluctuations. Here we show how experimentally measured fluctuation parameters be used determine inherent...
Thickness fluctuations have long been predicted in biological membranes but never directly observed experimentally. Here, we utilize neutron spin echo spectroscopy to experimentally reveal such a pure, fully saturated, phosphocholine lipid bilayer system. These appear as an excess the dynamics of undulation fluctuations. Like bending rigidity, thickness change dramatically transition temperature is crossed, appearing be completely suppressed below transition. Above transition, relaxation...
We have performed the heat capacity, neutron diffraction, and quasielastic scattering measurements of an ionic liquid 1-octyl-3-methylimidazolium chloride (C8mimCl). The capacity data revealed that C8mimCl exhibits a glass transition with large jump at T(g) = 214 K, which is lower than C4mimCl shorter alkyl-chain. In diffraction measurement for deuterated analogue, d-C8mimCl, peaks associated inter-domain, inter-ionic, inter-alkyl-chain correlations appeared (3, 11, 14) nm(-1), respectively....
The giant-resonance region in $^{208}\mathrm{Pb}$ was observed by inelastic electron scattering. We present evidence for the existences of a ${2}^{+}$ (or ${0}^{+}$) state at \ensuremath{\sim} 22 MeV and ${3}^{\ensuremath{-}}$ 19 with character. resonance states between 8.6 11.6 are confirmed to be sum their strengths exhausts about 50% $E2$ rule or 100% $E0$.
Short- and long-range correlations between solutes in solvents can influence the macroscopic chemistry physical properties of solutions ways that are not fully understood. The class liquids known as complex (structured) fluids-containing multiscale aggregates resulting from weak self-assembly-are especially important energy-relevant systems employed for a variety chemical- biological-based purification, separation, catalytic processes. In these, solute (mass) transfer across liquid-liquid...
The elastic and viscous properties of biological membranes play a vital role in controlling cell functions that require local reorganization the membrane components as well dramatic shape changes such endocytosis, vesicular trafficking, division. These are widely acknowledged to depend on unique composition lipids within membrane, yet effects lipid mixing biophysical remain poorly understood. Here, we present comprehensive characterization structural, elastic, fluid composed binary mixtures...
The small-angle neutron scattering instrument, SANS-U, owned by the Institute for Solid State Physics, University of Tokyo, has been upgraded. SANS-U is a 32 m SANS instrument installed in 1991 at guide hall JRR-3M research reactor Japan Atomic Energy Research Institute, and serving inter-university cooperative use since 1993. major upgrades include (i) replacement two-dimensional area detector multi-wire type position-sensitive proportional counter, (ii) renewal operating system from VAX...
We have used neutron spin echo (NSE) spectroscopy to study the effect of bilayer thickness and monounsaturation (existence a single double bond on one aliphatic chains) physical properties unilamellar vesicles. The bending elasticity saturated monounsaturated phospholipid bilayers made phospholipids with alkyl chain length ranging from 14 20 carbons was investigated. κ(c) phosphatidylcholines (PCs) in liquid crystalline (L(α)) phase ranges 0.38 × 10(-19) J for...
We report in situ nanostructures and dynamics of polybutadiene (PB) chains bound to carbon black (CB) fillers (the so-called "bound polymer layer (BPL)") a good solvent. The BPL on the CB was extracted by solvent leaching CB-filled PB compound subsequently dispersed deuterated toluene label for small-angle neutron scattering spin echo techniques. results demonstrate that is composed two regions regardless molecular weights PB: inner unswollen region ≈ 0.5 nm thick outer swollen where display...
The outbreak of electronic-cigarette/vaping-associated lung injury (EVALI) has made thousands ill. This been attributed to a physical interaction between toxicants from the vaping solution and pulmonary surfactant. In particular, studies have implicated vitamin E acetate as potential instigator EVALI. Pulmonary surfactant is vital proper respiration through mechanical processes adsorption interface stability achieve maintain low surface tension at air-liquid interface. Using neutron spin...
Membrane viscosity is a fundamental property that controls molecular transport and structural rearrangements in lipid membranes. Given its importance many cell processes, various experimental computational methods have been developed to measure the membrane viscosity, yet estimated values depend highly on method vary by orders of magnitude. Here we investigate origins measuring nanoscale dynamics acyl tails using x-ray neutron spectroscopy techniques. The results show can be from relaxation...
An important mechanical property of cells is the membrane bending modulus, κ. In case red blood (RBCs) there a composite consisting cytoplasmic and an underlying spectrin network. Literature values κ are puzzling, as they reported over wide range, from 5 kBT to 230 kBT. To disentangle contribution network, we investigated cell membranes (RBCcm) in absence adenosine triphosphate (ATP). We used combination X-ray diffuse scattering (XDS), neutron spin-echo (NSE) spectrometry Molecular Dynamics...
The popularity of electronic cigarettes and vaping products has launched the outbreak a condition affecting respiratory system users, known as electronic-cigarette/vaping-associated lung injury (EVALI). build-up vitamin E acetate (VEA), diluent some illicit oils, in bronchoalveolar lavage patients with EVALI provided circumstantial evidence target for investigation. In this work, we provide fundamental characterization interaction VEA cells pulmonary surfactant (PS) models to explore...
Pressure-induced phase separation of poly(N-isopropylacrylamide) (PNIPA) aqueous solutions and gels were investigated by small-angle neutron scattering (SANS). The cloud point curves constructed on the pressure−temperature (P−T) plane visual observation for both gels. As observed in diagram proteins, temperatures (Tcloud) a function pressure, P, had maxima at P0 = 51.7 MPa 93.2 respectively solution gel H2O. difference Tcloud indicates that effect cross-linking is significant, it leads to an...
We prepared five pairs of hydrogenous and deuterated ring polystyrene samples over a wide range molecular weights (10 kg/mol ≤ Mw 400 kg/mol) investigated their chain conformations in bulk by small-angle neutron scattering (SANS) measurements. From the SANS profiles obtained, we estimated radii gyration Rg polymers Guinier approximation. can be related to degree polymerization N as ∼ N0.47. This scaling exponent ν = 0.47 ± 0.01 is evidently smaller than that for Gaussian chains (ν 0.50) but...
The addition of nanofillers to rubber matrices is a powerful route improve the mechanical properties. Here, we focus on molecular understanding basic mechanisms that are important for reinforcement in rubbers. key role this process ascribed bound (BR) engages with matrix as well adjacent nanofillers. To date, has been impeded by lack experimental tools directly probe BR chains buried polymer composed same polymer. tackle challenge, combine neutron scattering/spectroscopy techniques...
Phase separation of acetonitrile−water mixtures by addition NaCl has been studied on the molecular level large-angle X-ray scattering (LAXS) and small-angle neutron (SANS) methods. A phase diagram acetonitrile−water−NaCl at 298 K shown that occurs over a wide range acetonitrile mole fraction (xAN) ∼0.1 < xAN ≤ ∼0.7, where microheterogeneity occurs. The radial distribution functions obtained LAXS measurements have revealed before amounts preferentially hydrated Na+ Cl- gradually increase with...