National Emergency Tele-Critical Care in a Pandemic: Barriers and Solutions.

The COVID-19 pandemic caused tremendous disruption to the U.S. healthcare system and nearly crippled some hospitals during large patient surges. Limited ICU beds across the country further exacerbated these challenges. Telemedicine, specifically tele-critical care (TCC), can expand a hospital's clinical capabilities through remote expertise and increase capacity by offloading some monitoring to remote teams. Unfortunately, the rapid deployment of telemedicine, especially TCC, is constrained by multiple barriers. In the summer of 2020, to support the National Emergency Tele-Critical Care Network (NETCCN) deployment, more than 50 national leaders in applying telemedicine technologies to critical care assembled to provide their opinions about barriers to NETCCN implementation and strategies to overcome them. Through consensus, these experts developed white papers that formed the basis of this article. Herein, the authors share their experience and propose multiple solutions to barriers presented by laws, local policies and cultures, and individual perspectives according to a minimum, better, best paradigm for TCC delivery in the setting of a national disaster. Cross-state licensure and local privileging of virtual experts were identified as the most significant barriers to rapid deployment of services, whereas refining the model of TCC to achieve the best outcomes and defining the best financial model is the most significant for long-term success. Ultimately, we conclude that a rapidly deployable national telemedicine response system is achievable.

DES-ultrasonication treatment of cellulose nanocrystals and the reinforcement in carrageenan biocomposite.

CNCs are intensively studied to reinforce biocomposites. However, it remains a challenge to homogeneously disperse the CNC in biocomposites for a smooth film surface. Mechanochemical treatment via ultrasonication in deep eutectic solvent (DES) generated a stable dispersion of CNC before incorporation into carrageenan biocomposite. Shifted peaks of choline chloride (ChCl) methylene groups to 3.95-3.98 ppm in 1H NMR indicated a formation of eutectic mixture between the hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) at the functional group of CH3···OH. The swelling of CNC in the DES was proven by the formation of intermolecular H-bond at a length of 2.46 Å. The use of DES contributed to a good dispersion of CNC in the solution which increased zeta potential by 43.2 % compared to CNC in deionized water. The ultrasonication amplitude and feed concentration were varied for the best parameters of a stable dispersion of CNC. The crystallinity of 1 wt% of CNC at 20 % sonication amplitude improved from 76 to 81 %. The high crystallinity of CNCDES resulted in an increase in film tensile and capsule loop strength of Carra-CNCDES by 20.7 and 19.4 %, respectively. Improved dispersion of CNCDES reduced the surface roughness of the biocomposite by 21.8 %. H-bond network in CNCDES improved the biocomposite properties for an ingenious reinforcement material.

Time-Temperature Superposition of the Dissolution of Wool Yarns in the Ionic Liquid 1-Ethyl-3-methylimidazolium Acetate.

The dissolution of wool yarns in the ionic liquid 1-ethyl-3-methyl-imidazolium acetate [C2mim][OAc] has been investigated. Wool yarns were submerged into [C2mim][OAc] and dissolved for various times and temperatures before coagulating with water. Optical microscopy was used to track the yarn's cross-sectional area. We propose that there are two competing dissolution processes, one rate-limited by disulfide bonds at low temperatures (LTs), and a second by hydrogen bonds at high temperatures (HTs), with a crossover point between the two regimes at 70 ℃. The corresponding activation energies were ELT = 127 ± 9 kJ/mol and EHT = 34 ± 1 kJ/mol. The remaining area of the dissolved wool yarn could be shifted via time-temperature superposition to plot a single master curve of area against time for both regions. Finally, the dissolution could be modelled by a diffusion process, giving self-diffusion coefficients for the [C2mim][OAc] ions (0.64-15.31 × 10-13 m2/s).

The Formation of All-Silk Composites and Time-Temperature Superposition.

Extensive studies have been conducted on utilising natural fibres as reinforcement in composite production. All-polymer composites have attracted much attention because of their high strength, enhanced interfacial bonding and recyclability. Silks, as a group of natural animal fibres, possess superior properties, including biocompatibility, tunability and biodegradability. However, few review articles are found on all-silk composites, and they often lack comments on the tailoring of properties through controlling the volume fraction of the matrix. To better understand the fundamental basis of the formation of silk-based composites, this review will discuss the structure and properties of silk-based composites with a focus on employing the time-temperature superposition principle to reveal the corresponding kinetic requirements of the formation process. Additionally, a variety of applications derived from silk-based composites will be explored. The benefits and constraints of each application will be presented and discussed. This review paper will provide a useful overview of research on silk-based biomaterials.

Pyrolysis activation energy of cellulosic fibres investigated by a method derived from the first order global model.

The pyrolysis kinetics of cellulosic fibres, a natural cotton yarn (NCY) and a mercerized cotton yarn (MCY), has been explored with a modified first order global analysis method (FOG), via a series of non-isothermal experiments, using thermogravimetric analysis (TGA). The modified FOG analysis routine was developed to overcome discrepancy in heating rate and the difference between exact results and approximations in integrals. The intrinsic pyrolysis activation energy, with temperature range tending to zero, was found to be independent of heating rate and approximation used, giving average values of 153 ± 2 kJ/mol for NCY and 192 ± 7 kJ/mol for MCY. This proves the applicability of the reported analysis routine under the conducted TGA measurements. The reasons for different values were hypothesized to be the difference in chemical composition and crystalline structure. The findings provide a new approach in the investigation on pyrolysis kinetics of biomass and factors impacting their pyrolytic behaviour.

Effect of Oil on Cellulose Dissolution in the Ionic Liquid 1-Butyl-3-methyl Imidazolium Acetate.

While ionic liquids (ILs) are well known to be excellent solvents for cellulose, the exact mechanism of dissolution has been a much disputed topic in recent years and is still not completely clear. In this work, we add to the current understanding and highlight the importance of hydrophobic interactions, through studying cellulose dissolution in mixtures of 1-butyl-3-methyl imidazolium acetate (BmimAc) and medium-chain triglyceride (MCT) oil. We demonstrate that the order in which constituents are mixed together plays a key role, through nuclear magnetic resonance (NMR) spectroscopic analysis. When small quantities of MCT oil (0.25-1 wt %) were introduced to BmimAc before cellulose, the effect on BmimAc chemical shift values was much more significant compared to when the cellulose was dissolved first, followed by oil addition. Rheological analysis also showed small differences in the viscosities of oil-cellulose-BmimAc solutions, depending on the order the constituents were added. On the other hand, no such order effect on the NMR results was observed when cellulose was replaced with cellobiose, suggesting that this observation is unique to the macromolecule. We propose that a cellulose-oil interaction develops but only when the cellulose structure has a sufficient degree of order and not when the cellulose is molecularly dispersed, since the hydrophobic cellulose plane is no longer intact. In all cases, cellulose-BmimAc-oil solutions were stable for at least 4 months. To our knowledge, this is the first work that investigates the effect of oil addition on the dissolving capacity of BmimAc and highlights the need for further re-evaluation of accepted mechanisms for cellulose dissolution in ILs.

A study of the interaction between TMAO and urea in water using NMR spectroscopy.

Trimethylamine N-oxide (TMAO) and urea are small organic biological molecules. While TMAO is known as a protective osmolyte that promotes the native form of biomolecules, urea is a denaturant. An understanding of the impact of TMAO and urea on water structure may aid in uncovering the molecular mechanisms that underlie this activity. Here we investigate binary solutions of TMAO-water, urea-water and ternary solutions of TMAO-urea-water using NMR spectroscopy at 300 K. An enhancement of the total hydrogen bonding in water was found upon the addition of TMAO and this effect was neutralised by a mole ratio of 1-part TMAO to 4-parts urea. Urea was found to have little effect on the strength of water's hydrogen bonding network and the dynamics of water molecules. Evidence was found for a weak interaction between TMAO and urea. Taken together, these results suggest that TMAO's function as a protective osmolyte, and its counteraction of urea, may be driven by the strength of its hydrogen bond interactions with water, and by a secondary reinforcement of water's own hydrogen bond network. They also suggest that the TMAO-urea complex forms through the donation of a hydrogen bond by urea.

Three methods to measure the dissolution activation energy of cellulosic fibres using time-temperature superposition.

Three methods are established to explore the dissolution kinetics of cellulosic fibres in the ionic liquid 1-ethyl-3-methyl-imidazolium acetate ([C2mim][OAc]), based on optical microscopic images of processed dried cellulose and cellulose hydrogels. The dissolution process for different times at various temperatures was analysed using time-temperature superposition, and from this the dissolution was found to follow an Arrhenius behaviour. Three values for the activation energy of dissolution were obtained from three different quantifying methods; these were found to agree, giving an average value of 73 ± 2 kJ/mol. A new method is developed to determine the swelling ratio of different regions of the processed cellulose samples, along with the different water volume fractions contained therein. The findings will be of interest to researchers making all cellulose composites and those studying the dissolution of cellulose by ionic liquids.

Bridging Structure, Dynamics, and Thermodynamics: An Example Study on Aqueous Potassium Halides.

Aqueous salt systems are ubiquitous in all areas of life. The ions in these solutions impose important structural and dynamic perturbations to water. In this study, we employ a combined neutron scattering, nuclear magnetic resonance, and computational modeling approach to deconstruct ion-specific perturbations to water structure and dynamics and shed light on the molecular origins of bulk thermodynamic properties of the solutions. Our approach uses the atomistic scale resolution offered to us by neutron scattering and computational modeling to investigate how the properties of particular short-ranged microenvironments within aqueous systems can be related to bulk properties of the system. We find that by considering only the water molecules in the first hydration shell of the ions that the enthalpy of hydration can be determined. We also quantify the range over which ions perturb water structure by calculating the average enthalpic interaction between a central halide anion and the surrounding water molecules as a function of distance and find that the favorable anion-water enthalpic interactions only extend to ∼4 Å. We further validate this by showing that ions induce structure in their solvating water molecules by examining the distribution of dipole angles in the first hydration shell of the ions but that this perturbation does not extend into the bulk water. We then use these structural findings to justify mathematical models that allow us to examine perturbations to rotational and diffusive dynamics in the first hydration shell around the potassium halide ions from NMR measurements. This shows that as one moves down the halide series from fluorine to iodine, and ionic charge density is therefore reduced, that the enthalpy of hydration becomes less negative. The first hydration shell also becomes less well structured, and rotational and diffusive motions of the hydrating water molecules are increased. This reduction in structure and increase in dynamics are likely the origin of the previously observed increased entropy of hydration as one moves down the halide series. These results also suggest that simple monovalent potassium halide ions induce mostly local perturbations to water structure and dynamics.

Rheological and NMR Studies of Cellulose Dissolution in the Ionic Liquid BmimAc.

Solutions of two types of cellulose in the ionic liquid 1-butyl-3-methyl-imidazolium acetate (BmimAc) have been analyzed using rheology and fast-field cycling nuclear magnetic resonance (NMR) spectroscopy, in order to analyze the macroscopic (bulk) and microscopic environments, respectively. The degree of polymerization (DP) was observed to have a significant effect on both the overlap (c*) and entanglement (ce) concentrations and the intrinsic viscosity ([η]). For microcrystalline cellulose (MCC)/BmimAc solutions, [η] = 116 mL g-1, which is comparable to that of MCC/1-ethyl-3-methyl-imidazolium acetate (EmimAc) solutions, while [η] = 350 mL g-1 for the commercial cellulose (higher DP). Self-diffusion coefficients (D) obtained via the model-independent approach were found to decrease with cellulose concentration and increase with temperature, which can in part be explained by the changes in viscosity; however, ion interactions on a local level are also important. Both Stokes-Einstein and Stokes-Einstein-Debye analyses were carried out to directly compare rheological and relaxometry analyses. It was found that polymer entanglements affect the microscopic environment to a much lesser extent than for the macroscopic environment. Finally, the temperature dependencies of η, D, and relaxation time (T1) could be well described by Arrhenius relationships, and thus, activation energies (Ea) for flow, diffusion, and relaxation were determined. We demonstrate that temperature and cellulose concentration have different effects on short- and long-range interactions.

Time-Temperature Superposition of the Dissolution of Silk Fibers in the Ionic Liquid 1-Ethyl-3-methylimidazolium Acetate.

This study investigated the dissolution of silk multifilament fibers in the ionic liquid 1-ethyl-3-methylimidazolium acetate. The dissolution process was found to create a silk composite fiber, comprising undissolved silk multifilaments surrounded by a coagulated silk matrix. The dissolution procedure was carried out for a range of temperatures and times. The resulting composite fibers were studied using a combination of optical microscopy, wide-angle X-ray diffraction (XRD), and tensile testing. An azimuthal (α) XRD scan enabled the orientation of the composite silk filaments to be quantified through a second Legendre polynomial function (P2). The P2 results could be shifted to construct a single master curve using time-temperature superposition (TTS). The shifting factors were found to have an Arrhenius behavior with an activation energy of 138 ± 13 kJ/mol. Using a simple rule of mixtures, the P2 measurements were used to calculate the dissolved silk matrix volume fraction (Vm), which also displayed TTS forming a single master curve with an activation energy of 139 ± 15 kJ/mol. The tensile Young's modulus of each silk composite filament was measured, and these results similarly formed a master curve with an activation energy of 116 ± 12 kJ/mol.

Oxidized Zirconium Components Maintain a Smooth Articular Surface Except Following Hip Dislocation.

BACKGROUND: Oxidized zirconium (OxZr) offers theoretical advantages in total hip and knee arthroplasty (THA and TKA, respectively) relative to other biomaterials by combining the tribological benefits of ceramics with the fracture toughness of metals. Yet, some studies have found that OxZr does not improve outcomes or wear rates relative to traditional bearing materials such as cobalt-chromium (CoCr). Separately, effacement of the thin ceramic surface layer has been reported for OxZr components, though the prevalence and sequelae are unclear. METHODS: To elucidate the in vivo behavior of OxZr implants, the articular surfaces of 94 retrieved THA and TKA femoral components (43 OxZr TKA, 21 OxZr THA, 30 CoCr THA) were analyzed using optical microscopy, non-contact profilometry, and scanning electron microscopy. RESULTS: We found that OxZr components maintain a smooth articular surface except following hip dislocation. Three of four OxZr femoral heads revised following dislocation exhibited severe damage to the articular surface, including macroscopic regions of ceramic-layer effacement and exposure of the underlying metal substrate; these components were 23-32 times rougher than pristine OxZr controls. When revised for dislocation, OxZr femoral heads were substantially rougher than CoCr femoral heads (median Sa = 0.431 v. 0.020 µm, P = .03). In contrast, CoCr femoral heads exhibited low overall roughness values regardless of whether they dislocated (median Sa = 0.020 v. 0.008 µm, P = .09, CoCr dislocators v. non-dislocators). CONCLUSIONS: Effacement of the ceramic surface layer and substantial articular surface roughening is not atypical following dislocation of OxZr femoral heads, making OxZr much less tolerant than CoCr to hip dislocation.

Solute Specific Perturbations to Water Structure and Dynamics in Tertiary Aqueous Solution.

Liquid water is known as the "universal" solvent, capable of dissolving a wide variety of different solutes. While much is now understood about the impact of solutes on the water structure in binary solutions, it is much more challenging to deconvolute the potentially competing effects of more complex solutions. Here, we present a correlative NMR and neutron diffraction study to examine the solute induced perturbation of water structure and dynamics in a tertiary solution containing the naturally occurring osmolyte trimethylamine N-oxide (TMAO) and magnesium perchlorate (Mg(ClO4)2). We show that while TMAO and Mg(ClO4)2 perturb the water structure in an opposing manner, the two solutes slow water dynamics in an additive manner. We quantify the relative ability of each solute to perturb water by introducing a weighting parameter and show that TMAO is 1.54 times more effective at perturbing water structure and dynamics than Mg(ClO4)2. The combination of NMR, neutron diffraction, and computational modelling offers unprecedented access to the structure and dynamics of more complex aqueous solutions, permitting the deconvolution of solute specific perturbation of water. Such insight provides a new route to understand this universal solvent in the context of important and relevant aqueous environments.