The Polarity of Co-solvents Regulates the Charge Storage Mechanisms in Supercapacitors with Concentrated Electrolytes.

Developing better energy storage devices depends on comprehending the underlying mechanisms involved in charge storage. With the continuous conception of new electrolytes, this task becomes progressively more urgent and complex. An example is the utilization of co-solvated concentrated solutions.

Backscattering silicon spectrometer (BASIS): sixteen years in advanced materials characterization.

Quasielastic neutron scattering (QENS) is an experimental technique that can measure parameters of mobility, such as diffusion jump rate and jump length, as well as localized relaxations of chemical species (molecules, ions, and segments) at atomic and nanometer length scales. Due to the high penetrative power of neutrons and their sensitivity to neutron scattering cross-section of chemical species, QENS can effectively probe mobility inside most bulk materials. This review focuses on QENS experiments performed using a neutron backscattering silicon spectrometer (BASIS) to explore the dynamics in various materials and understand their structure-property relationship.

Testing the hypothesis that solvent exchange limits the rates of calcite growth and dissolution.

It is established that the rates of solvent exchange at interfaces correlate with the rates of a number of mineral reactions, including growth, dissolution and ion sorption. To test if solvent exchange is limiting these rates, quasi-elastic neutron scattering (QENS) is used here to benchmark classical molecular dynamics (CMD) simulations of water bound to nanoparticulate calcite. Four distributions of solvent exchanges are found with residence times of 8.

Neutron Instruments for Research in Coordination Chemistry.

Neutron diffraction and spectroscopy offer unique insight into structures and properties of solids and molecular materials. All neutron instruments located at the various neutron sources are distinct, even if their designs are based on similar principles, and thus, they are usually less familiar to the community than commercial X-ray diffractometers and optical spectrometers. Major neutron instruments in the USA, which are open to scientists around the world, and examples of their use in coordination chemistry research are presented here, along with a list of similar instruments at main neutron facilities in other countries.

Nonstereotypical Distribution and Effect of Ergosterol in Lipid Membranes.

Ergosterol, found in fungi and some protist membranes, is understudied compared with cholesterol from animal membranes. Generally, ergosterol is assumed to modulate membranes in the same manner as cholesterol, based on their similar chemical structures. Here we reveal some fundamental structural and dynamical differences between them.

Diffusion Dynamics of Water and Ethanol in Graphene Oxide.

We utilized the momentum transfer ()-dependence of quasi-elastic neutron scattering (QENS) to measure the dynamics of water and ethanol confined in graphene oxide (GO) powder or membranes at different temperatures and in different orientations. We found reduced diffusivities (up to 30% in the case of water) and a depression of dynamic transition temperatures. While water showed near Arrhenius behavior with an almost bulk-like activation barrier in a temperature range of 280-310 K, the diffusivity of ethanol showed little temperature dependence.

Machine-learning-assisted material discovery of oxygen-rich highly porous carbon active materials for aqueous supercapacitors.

Porous carbons are the active materials of choice for supercapacitor applications because of their power capability, long-term cycle stability, and wide operating temperatures. However, the development of carbon active materials with improved physicochemical and electrochemical properties is generally carried out via time-consuming and cost-ineffective experimental processes. In this regard, machine-learning technology provides a data-driven approach to examine previously reported research works to find the critical features for developing ideal carbon materials for supercapacitors.

Neutron Scattering Studies of Heterogeneous Catalysis.

Understanding the structural dynamics/evolution of catalysts and the related surface chemistry is essential for establishing structure-catalysis relationships, where spectroscopic and scattering tools play a crucial role. Among many such tools, neutron scattering, though less-known, has a unique power for investigating catalytic phenomena. Since neutrons interact with the nuclei of matter, the neutron-nucleon interaction provides unique information on light elements (mainly hydrogen), neighboring elements, and isotopes, which are complementary to X-ray and photon-based techniques.

Search for a Grotthuss mechanism through the observation of proton transfer.

The transport of protons is critical in a variety of bio- and electro-chemical processes and technologies. The Grotthuss mechanism is considered to be the most efficient proton transport mechanism, generally implying a transfer of protons between 'chains' of host molecules via elementary reactions within the hydrogen bonds. Although Grotthuss proposed this concept more than 200 years ago, only indirect experimental evidence of the mechanism has been observed.

Lateral diffusion of lipids in the DMPG membrane across the anomalous melting regime: effects of NaCl.

The anionic dimyristoyl phosphatidylglycerol (DMPG) membrane in solvents with a low ionic strength is known to exhibit an unusually wide melting regime between the gel and fluid phase characterized by various anomalous macroscopic characteristics, such as low turbidity and high electrical conductivity and viscosity. A recent neutron spin echo study [Kelley, E. G.

A Molecular Description of Hydrogel Forming Polymers for Cement-Based Printing Paste Applications.

This research endeavors to link the physical and chemical characteristics of select polymer hydrogels to differences in printability when used as printing aids in cement-based printing pastes. A variety of experimental probes including differential scanning calorimetry (DSC), NMR-diffusion ordered spectroscopy (DOSY), quasi-elastic neutron scattering (QENS) using neutron backscattering spectroscopy, and X-ray powder diffraction (XRD), along with molecular dynamic simulations, were used. Conjectures based on objective measures of printability and physical and chemical-molecular characteristics of the polymer gels are emerging that should help target printing aid selection and design, and mix formulation.

Exploring the Limits of Biological Complexity Amenable to Studies by Incoherent Neutron Spectroscopy.

The wavelengths of neutrons available at neutron scattering facilities are comparable with intra- and inter-molecular distances, while their energies are comparable with molecular vibrational energies, making such neutrons highly suitable for studies of molecular-level dynamics. The unmistakable trend in neutron spectroscopy has been towards measurements of systems of greater complexity. Several decades of studies of dynamics using neutron scattering have witnessed a progression from measurements of solids to liquids to protein complexes and biomembranes, which may exhibit properties characteristic of both solids and liquids.

Exceptionally Fast Ion Diffusion in Block Copolymer-Based Porous Carbon Fibers.

Confined ionic liquids in hydrophilic porous media have disrupted lattices and can be divided into two layers: An immobile ion layer adheres to the pore surfaces, and an inner layer exhibits faster mobility than the bulk. In this work, we report the first study of ionic liquids confined in block copolymer-based porous carbon fibers (PCFs) synthesized from polyacrylonitrile--polymethyl methacrylate (PAN--PMMA). The PCFs contain a network of unimodal mesopores of 13.

Multiscale lipid membrane dynamics as revealed by neutron spectroscopy.

The plasma membrane is one of the principal structural components of the cell and, therefore, one of the key components of the cellular life. Because the membrane's dynamics links the membrane's structure and function, the complexity and the broad range of the membrane's motions are essential for the enormously diverse functionality of the cell membrane. Even for the main membrane component, the lipid bilayer, considered alone, the range and complexity of the lipid motions are remarkable.

Water Dynamics in Cancer Cells: Lessons from Quasielastic Neutron Scattering.

The severity of the cancer statistics around the globe and the complexity involving the behavior of cancer cells inevitably calls for contributions from multidisciplinary areas of research. As such, materials science became a powerful asset to support biological research in comprehending the macro and microscopic behavior of cancer cells and untangling factors that may contribute to their progression or remission. The contributions of cellular water dynamics in this process have always been debated and, in recent years, experimental works performed with Quasielastic neutron scattering (QENS) brought new perspectives to these discussions.

A concept of a broadband inverted geometry spectrometer for the Second Target Station at the Spallation Neutron Source.

BWAVES is an acronym for Broadband Wide-Angle VElocity Selector spectrometer, indicating that a novel WAVES (Wide-Angle VElocity Selector) device will be used to select the velocity/wavelength of the detected neutrons after they are scattered by the sample. We describe a conceptual design of BWAVES, a time-of-flight broadband inverted-geometry neutron spectrometer for the Second Target Station at the Spallation Neutron Source operated by Oak Ridge National Laboratory. Being the first inverted geometry spectrometer where the energy of the detected neutrons can be chosen by a WAVES device mechanically, irrespective of the limitations imposed by the crystal analyzers or filters, BWAVES will feature a uniquely broad, continuous dynamic range of measurable energy transfers, spanning 4.

Direct Correlation of the Salt-Reduced Diffusivities of Organic Solvents with the Solvent's Mole Fraction.

Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in organic solvents (especially propylene carbonate) has demonstrated extraordinary pseudocapacitive performance as an electrolyte in the supercapacitor configuration ( 2019, 4, 241-248). However, the influence of the solvated ions on the diffusivity of the solvent molecules is yet to be understood. We examine the impact of LiTFSI on the diffusivity in five organic solvents: acetonitrile (ACN), tetrahydrofuran (THF), methanol (MeOH), dimethyl sulfoxide (DMSO), and propylene carbonate (PC) using a combination of neutron scattering, conductivity measurements, and molecular dynamics simulations.

Experimental mapping of short-wavelength phonons in proteins.

Phonons are quasi-particles, observed as lattice vibrations in periodic materials, that often dampen in the presence of structural perturbations. Nevertheless, phonon-like collective excitations exist in highly complex systems, such as proteins, although the origin of such collective motions has remained elusive. Here we present a picture of temperature and hydration dependence of collective excitations in green fluorescent protein (GFP) obtained by inelastic neutron scattering.

Melting and Re-Freezing Leads to Irreversible Changes in the Morphology and Molecular-Level Dynamics of Pfizer-BioNTech COVID-19 Vaccine.

: As an mRNA-based vaccine, the Pfizer-BioNTech COVID-19 vaccine has stringent cold storage requirements to preserve functionality of the mRNA active ingredient. To this end, lipid components of the vaccine formulation play an important role in stabilizing and protecting the mRNA molecule for long-term storage. The purpose of the current study was to measure molecular-level dynamics as a function of temperature in the Pfizer-BioNTech COVID-19 vaccine to gain microscopic insight into its thermal stability.

Dynamics of Emim in [Emim][TFSI]/LiTFSI Solutions as Bulk and under Confinement in a Quasi-liquid Solid Electrolyte.

Quasi-liquid solid electrolytes are a promising alternative for next-generation Li batteries. These systems combine the safety of solid electrolytes with the desired properties of liquids and are typically formed by solutions of Li salts in ionic liquids incorporated into solid matrices. Here, we present a fundamental understanding of the transport properties in solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]), either in bulk form or incorporated in a boron nitride (BN) matrix.

Low rotational barriers for the most dynamically active methyl groups in the proposed antiviral drugs for treatment of SARS-CoV-2, apilimod and tetrandrine.

A recent screening study highlighted a molecular compound, apilimod, for its efficacy against the SARS-CoV-2 virus, while another compound, tetrandrine, demonstrated a remarkable synergy with the benchmark antiviral drug, remdesivir. Here, we find that because of significantly reduced potential energy barriers, which also give rise to pronounced quantum effects, the rotational dynamics of the most dynamically active methyl groups in apilimod and tetrandrine are much faster than those in remdesivir. Because dynamics of methyl groups are essential for biochemical activity, screening studies based on the computed potential energy profiles may help identify promising candidates within a given class of drugs.

Strong Enhancement of Nanoconfined Water Mobility by a Structure Breaking Salt.

For the majority of the water present on earth, the two most important factors influencing its behavior are confinement, in either inorganic or organic matrixes, and the presence of solutes. Here, we investigate the effect of confinement in 3 nm pores on water diffusivity in aqueous solutions with archetypical solutes, a structure making (kosmotrope) NaCl and a structure breaking (chaotrope) KCl, up to 1.0 M in concentration.