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The energy efficiency, mechanical durability, and environmental compatibility of all moving machine components rely heavily on advanced lubricants for smooth and safe operation. Herein an alternative family of high-quality liquid (HQL) lubricants was derived by the catalytic conversion of pre- and post-consumer polyolefin waste. The plastic-derived lubricants performed comparably to synthetic base oils such as polyalphaolefins (PAOs), both with a wear scar volume (WSV) of 7.5×10-5 mm-3 . HQLs also performed superior to petroleum-based lubricants such as Group III mineral oil with a WSV of 1.7×10-4 mm-3 , showcasing a 44 % reduction in wear. Furthermore, a synergistic reduction in friction and wear was observed when combining the upcycled plastic lubricant with synthetic oils. Life cycle and techno-economic analyses also showed this process to be energetically efficient and economically feasible. This novel technology offers a cost-effective opportunity to reduce the harmful environmental impact of plastic waste on our planet and to save energy through reduction of friction and wear-related degradations in transportation applications akin to synthetic oils.

We measure the center-of-mass diffusion of silica nanoparticles (NPs) in entangled poly(2-vinylpyridine) (P2VP) melts using Rutherford backscattering spectrometry. While these NPs are well within the size regime where enhanced, nonhydrodynamic NP transport is theoretically predicted and has been observed experimentally (2RNP/dtube ≈ 3, where 2RNP is the NP diameter and dtube is the tube diameter), we find that the diffusion of these NPs in P2VP is in fact well-described by the hydrodynamic Stokes–Einstein relation. The effective NP diameter 2Reff is significantly larger than 2RNP and strongly dependent on P2VP molecular weight, consistent with the presence of a bound polymer layer on the NP surface with thickness heff ≈ 1.1Rg. Our results show that the bound polymer layer significantly augments the NP hydrodynamic size in polymer melts with attractive polymer–NP interactions and effectively transitions the mechanism of NP diffusion from the nonhydrodynamic to hydrodynamic regime, particularly at high mole...

Summary Living tissues are an integrated, multiscale architecture consisting of dense cellular ensembles and extracellular matrices (ECMs). The cells and ECMs cooperate to enable specialized mechanical properties and dynamic responsiveness. However, the mechanical properties of living tissues are difficult to replicate. A particular challenge is identification of a cell-like synthetic component, which is tightly integrated with its matrix and also responsive to external stimuli. Here, we demonstrate that cellular-scale hydrated starch granules, an underexplored component in materials science, can turn conventional hydrogels into tissue-like materials when composites are formed. By using several synchrotron-based X-ray techniques, we reveal the mechanically induced organization and training dynamics of the starch granules in the hydrogel matrix. These dynamic behaviors enable multiple tissue-like properties such as programmability, anisotropy, strain-stiffening, mechanochemistry, and self-healability.

The interfacial regions between nanoparticles (NPs) and polymers in polymer nanocomposites (PNCs) underlie enhanced properties, and the temporal stability of these bound polymer layers is necessary...

Polymer segmental dynamics, center-of-mass chain diffusion, and nanoparticle (NP) diffusion are directly measured in a series of polymer nanocomposites (PNC) composed of very small (radius ≈ 0.9 nm...

We present a systematic study of segmental dynamics in model attractive polymer nanocomposites comprising poly(2-vinylpyridine) (P2VP) and 26 nm diameter colloidal silica nanoparticles (NPs) using quasi-elastic neutron scattering (QENS). Unlike most dynamic measurements, QENS provides both spatial and temporal information about small length scales (∼1 nm) and fast time scales (∼1 ns) and therefore at temperatures far above the glass transition. We find that on these length and time scales P2VP segmental motion is well-described by classic translational diffusion even under extreme confinement, where the average interparticle spacing is on the order of the Kuhn length. The average segmental diffusion coefficient decreases monotonically with increasing NP concentration by up to a factor of ∼5 at the highest NP concentrations (50 vol %). Interestingly, this reduction in segmental dynamics is very weakly dependent on P2VP molecular weight spanning the unentangled (10 kg/mol) to the highly entangled regimes (1...

Mechano-activated chemistry is a powerful tool for remodeling of synthetic polymeric materials, however, few reactions are currently available. Here we show that using piezochemical reduction of a CuII -based pre-catalyst, a step-growth polymerization occurs via the copper catalyzed azide-alkyne cycloaddition (CuAAC) reaction to form a linear polytriazole. Furthermore, we show that a linear polymer can be crosslinked mechanochemically using the same chemistry to form a solid organogel. We envision that this chemistry can be used to harness mechanical energy for constructive purposes in polymeric materials.

Rapidly growing flexible and wearable electronics highly demand the development of flexible energy storage devices. Yet, these devices are susceptible to extreme, repeated mechanical deformations under working circumstances. Herein, the design and fabrication of a smart, flexible Li-ion battery with shape memory function, which has the ability to restore its shape against severe mechanical deformations, bending, twisting, rolling or elongation, is reported. The shape memory function is induced by the integration of a shape-adjustable solid polymer electrolyte. This Li-ion battery delivers a specific discharge capacity of ≈140 mAh g-1 at 0.2 C charge/discharge rate with ≈92% capacity retention after 100 cycles and ≈99.85% Coulombic efficiency, at 20 °C. Besides recovery from mechanical deformations, it is visually demonstrated that the shape of this smart battery can be programmed to adjust itself in response to an internal/external heat stimulus for task-specific and advanced applications. Considering the vast range of available shape memory polymers with tunable chemistry, physical, and mechanical characteristics, this study offers a promising approach for engineering smart batteries responsive to unfavorable internal or external stimulus, with potential to have a broad impact on other energy storage technologies in different sizes and shapes.

Ion transport in polymerized ionic liquids (poly-ILs) occurs via a fundamentally different mechanism than in monomeric ionic liquids, and recently progress has been made toward understanding ion conduction in poly-ILs. To gain insight into the nature of ionic conductivity in ionic polymers, we investigate the physical properties of the trisaminocyclopropenium (TAC) ion, as it is an aromatic carbocation with unique structural and electronic properties. Herein, we characterize the thermal properties, local morphology, and dielectric response of a series of monomeric and polymeric TAC ionic liquids with different counterions. We have found that the extent of a “superionic” mechanism depends on the nature of the ion pair and can result in anomalously high conductivity at the calorimetric Tg. Our results suggest that the molecular volumes of the cationic and anionic species are important parameters that impact ion conductivity in polymerized ionic liquids.

Optically actuated silicon structures reveal rapid calcium signal propagation in biofilms., Bacterial response to transient physical stress is critical to their homeostasis and survival in the dynamic natural environment. Because of the lack of biophysical tools capable of delivering precise and localized physical perturbations to a bacterial community, the underlying mechanism of microbial signal transduction has remained unexplored. Here, we developed multiscale and structured silicon (Si) materials as nongenetic optical transducers capable of modulating the activities of both single bacterial cells and biofilms at high spatiotemporal resolution. Upon optical stimulation, we capture a previously unidentified form of rapid, photothermal gradient–dependent, intercellular calcium signaling within the biofilm. We also found an unexpected coupling between calcium dynamics and biofilm mechanics, which could be of importance for biofilm resistance. Our results suggest that functional integration of Si materials and bacteria, and associated control of signal transduction, may lead to hybrid living matter toward future synthetic biology and adaptable materials.

The polymer center-of-mass tracer diffusion coefficient in athermal polymer nanocomposites (PNCs) composed of polystyrene and phenyl-capped, spherical silica nanoparticles was measured over a range of temperatures and nanoparticle concentrations using elastic recoil detection. The polymer tracer diffusion coefficient in the PNC relative to the bulk decreases with increasing nanoparticle concentration and is unexpectedly more strongly reduced at higher temperatures. This unusual temperature dependence of polymer diffusion in PNCs cannot be explained by the reptation model or a modified version incorporating an effective tube diameter. Instead we show that our results are consistent with a mechanism based on nanoparticle-imposed configurational entropy barriers.

The impact of supramolecular hydrogen bonded networks on dynamics and charge transport in 2-ethyl-4-methylimidazole (2E4MIm), a model proton-conducting system, is investigated by broadband dielectric spectroscopy, depolarized dynamic light scattering, viscometry, and calorimetry. It is observed that the slow, Debye-like relaxation reflecting the supramolecular structure in neat 2E4MIm is eliminated upon the addition of minute amounts of levulinic acid. This is attributed to the dissociation of imidazole molecules and the breaking down of hydrogen-bonded chains, which leads to a 10-fold enhancement of ionic conductivity.

We report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radii in the range of 30–100 nm. The nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. This finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.

We measure the center-of-mass diffusion of poly(methyl methacrylate) (PMMA)-grafted nanoparticles (NPs) in unentangled to slightly entangled PMMA melts using Rutherford backscattering spectrometry. These grafted NPs diffuse ∼100 times slower than predicted by the Stokes-Einstein relation assuming a viscosity equal to bulk PMMA and a hydrodynamic NP size equal to the NP core diameter, 2Rcore = 4.3 nm. This slow NP diffusion is consistent with an increased effective NP size, 2Reff ≈ 20 nm, nominally independent of the range of grafting density and matrix molecular weights explored in this study. Comparing these experimental results to a modified Daoud-Cotton scaling estimate for the brush thickness as well as dynamic mean field simulations of polymer-grafted NPs in athermal polymer melts, we find that 2Reff is in quantitative agreement with the size of the NP core plus the extended grafted chains. Our results suggest that grafted polymer chains of moderate molecular weight and grafting density may alter the NP diffusion mechanism in polymer melts, primarily by increasing the NP effective size.

The static and dynamic properties of poly(2-vinylpyridine)/silica nanocomposites are investigated by temperature modulated differential scanning calorimetry, broadband dielectric spectroscopy (BDS), small-angle X-ray scattering (SAXS), and transmission electron microscopy. Both BDS and SAXS detect the existence of an interfacial polymer layer on the surface of nanoparticles. The results show that whereas the calorimetric glass transition temperature varies only weakly with nanoparticle loading, the segmental mobility of the polymer interfacial layer is slower than the bulk polymer by 2 orders of magnitude. Detailed analysis of BDS and SAXS data reveal that the interfacial layer has a thickness of 4–6 nm irrespective of the nanoparticle concentration. These results demonstrate that in contrast to some recent articles on polymer nanocomposites, the interfacial polymer layer is by no means a “dead layer”. However, its existence might provide some explanation for controversies surrounding the dynamics of poly...

Detailed analysis of the static structure factor S(Q) in several glass-forming liquids reveals that the temperature variations of the width of the main diffraction peak ΔQ(T) correlate with the fragility of these liquids. This observation suggests a direct connection between rather subtle structural changes and sharp slowing down of structural relaxation in glass-forming liquids. We show that this observation can be rationalized using the Adam-Gibbs approach, through a connection between temperature variations of structural correlation length, l_{c}∼2π/ΔQ, and the size of cooperatively rearranging regions.

Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. Our detailed experimental studies discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. These results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects.

Charge transport and structural dynamics in the 1:2 mol ratio mixture of lidocaine and decanoic acid (LID-DA), a model deep eutectic mixture (DEM), have been characterized over a wide temperature range using broad-band dielectric spectroscopy and depolarized dynamic light scattering. Additionally, Fourier transform infrared spectroscopy measurements were performed to assess the degree of proton transfer between the neutral parent molecules. From our detailed analysis of the dielectric spectra, we have determined that this carboxylic-acid-based DEM is approximately 25% ionic at room temperature. Furthermore, we have found that the characteristic diffusion rate of mobile charge carriers is practically identical to the rate of structural relaxation at all measured temperatures, indicating that fast proton transport does not occur in LID-DA. Our results demonstrate that while LID-DA exhibits the thermal characteristics of a DEM, its charge transport properties resemble those of a protic ionic liquid.

In order to understand the nature of the exceedingly low ionic conductivity of aprotic ammonium ionic liquids (ILs), we have measured the charge transport and structural dynamics of methyltrioctylammonium bis(trifluoromethylsulfonyl)imide [m3oa][ntf2] over a broad temperature range using broadband dielectric spectroscopy, depolarized dynamic light scattering (DDLS), rheology, and pulsed field gradient nuclear magnetic resonance. We demonstrate that the low level of ionic conductivity in this material is due to the combined effects of reduced ion mobility as well as reduced free ion concentration relative to other types of ILs. Furthermore, detailed analysis of the DDLS spectra reveals a slow process in addition to the structural α relaxation that we attribute to reorientational motion of alkyl aggregates. These findings indicate that hydrophobic aggregation strongly influences the charge transport mechanism of aprotic ammonium ionic liquids with long aliphatic side chains.

We report measurements of the ionic conductivity, shear viscosity, and structural dynamics in a homologous series of quaternary ammonium ionic liquids (ILs) and a prototypical imidazolium-based IL over a wide range of temperatures down to the glass transition. We find that the ionic conductivity of these materials generally decreases, while the shear viscosity correspondingly increases, with increasing volume fraction of aliphatic side groups. Upon crossing an aliphatic volume fraction of ∼0.40, we observe a sharp, order-of-magnitude decrease in ionic conductivity and enhancement of viscosity, which coincides with the presence of long-lived, nanometer-sized alkyl aggregates. These strong changes in dynamics are not mirrored in the ionicity of these ILs, which decreases nearly linearly with aliphatic volume fraction. Our results demonstrate that nanophase segregation in neat ILs strongly reduces ionic conductivity primarily due to an aggregation-induced suppression of dynamics.

Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf(2)], [bmim][PF(6)], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward T(g). The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10(-11) s up to 10(2) s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature. We suggest that these phenomena are interconnected and all result from the same underlying mechanism--strong and directional intermolecular interactions.

Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward T(g). The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be T(c) ~ 225 ± 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process.

The slow, Debye-like relaxation in hydrogen-bonded liquids has largely remained a dielectric phenomenon and has thus far eluded observation by other experimental techniques. Here we report the first observation of a slow, Debye-like relaxation by both depolarized dynamic light scattering (DLS) and dielectric spectroscopy in a model hydrogen-bonded liquid, 2-ethyl-4-methylimidazole (2E4MIm). The relaxation times obtained by these two techniques are in good agreement and can be well explained by the Debye model of rotational diffusion. On the one hand, 2E4MIm is analogous to the widely studied monohydroxy alcohols in which transient chain-like supramolecular structure can be formed by hydrogen bonding. On the other hand, the hydrogen-bonded backbone of 2E4MIm is much more optically polarizable, making it possible to apply light scattering to study the dynamics of the supramolecular structure. These findings provide the missing evidence of the slow, Debye-like relaxation in DLS and open the venue for the application of dynamic light scattering to the study of supramolecular structures in hydrogen-bonded liquids.

The dynamic glass transition in the molecular liquid DEET is investigated in wide temperature and pressure ranges using depolarized dynamic light scattering (DDLS), broadband dielectric spectroscopy (BDS), calorimetry, and rheology. It is found that the viscosity and structural α relaxation rates all exhibit an identical type of thermal activation in the measured temperature and pressure ranges. In addition, it is shown that these characteristic quantities exhibit a dynamic crossover at 240 ± 5 K at ambient pressure. Contrary to recent assertions in the literature, it is demonstrated that the dynamic crossover by no means generally implies a violation of the Debye–Stokes–Einstein relation in molecular glass forming liquids.

Dynamics of water, especially in the temperature range of the "no man's land", remain a mystery. We present detailed study of dynamics in aqueous LiCl solution that is often considered as a model for bulk water. We employ broadband dielectric and light scattering spectroscopy in a broad frequency and temperature range. Our analysis reveals no sign of the fragile-to-strong crossover (FSC) neither in structural relaxation nor in translational motions. Our experimental results combined with a large selection of literature data lead to the clear conclusion-there is no FSC in dynamics of aqueous solutions at T ∼ 200-230 K. Instead, our analysis reveals appearance of the so-called excess wing at the high frequency tail of the structural relaxation peak. We discuss the localized nature of the relaxation process that contributes to the excess wing.

(1955). Kidney Disease in Brook Trout and its Treatment. The Progressive Fish-Culturist: Vol. 17, No. 1, pp. 3-13.

The purpose of this study was to establish a set of descriptive data which could be used as a reference or a standard in the identification of Bacterium salmonicida, the cause of furunculosis in fish. Since a complete description of B. salmonicida was not available, bacteriologists were not in a position to identify this microorganism in a manner which would meet the rigorous requirements of present-day bacteriology. Ten strains of B. salmonicida were employed in these studies. A detailed description is presented which includes the morphological, cultural, and physiological characteristics of B. salmonicida. In addition, various factors such as oxygen, pH, temperature, and composition of media are discussed in terms of their influence on the formation of the melanin-like pigment which is characteristically produced by this microorganism.

A review is made of the progress in research on bacteria which are pathogenic to fish, with particular emphasis on those investigations performed during the past decade. The report includes a critical review of material published; the comments and suggestions are designed to stimulate the initiation of new research projects.