Suppression of Segmental Chain Dynamics on a Particle's Surface in Well-Dispersed Polymer Nanocomposites.

The Rouse dynamics of polymer chains in model nanocomposite polyethylene oxide/silica nanoparticles (NPs) was investigated using quasielastic neutron scattering. The apparent Rouse rate of the polymer chains decreases as the particle loading increases. However, there is no evidence of an immobile segment population on the probed time scale of tens of ps. The slowing down of the dynamics is interpreted in terms of modified Rouse models for the chains in the NP interphase region. Thus, two chain populations, one bulk-like and the other characterized by a suppression of Rouse modes, are identified. The spatial extent of the interphase region is estimated to be about twice the adsorbed layer thickness, or ≈2 nm. These findings provide a detailed description of the suppression of the chain dynamics on the surface of NPs. These results are relevant insights on surface effects and confinement and provide a foundation for the understanding of the rheological properties of polymer nanocomposites with well-dispersed NPs.

Conceptual study of a new instrument for dynamic neutron scattering measurements-The modulated intensity with diffraction analysis spectrometer (MIDAS).

Dynamic neutron scattering probes unique nanoscale dynamics via measurement of energy exchanged between a sample and the neutrons. The two spectrometers that investigate processes with characteristic times around a nanosecond are backscattering (BS) and neutron spin-echo (NSE). We present a new method for measuring dynamics using an oscillating cosine-like energy-distribution neutron-package at the sample and measure solely the portion scattered into the elastic line. This portion corresponds to elastically scattered neutrons and, in addition, inelastic components that are scattered with a probability directly proportional to the cosine Fourier-coefficients of the exchanged-energy spectrum. The counts at the detector thus correspond to the van Hove intermediate scattering function. We denote this new method as "Fourier transform neutron scattering" (FTNS), it being broadly analogous to IR and Raman spectroscopies. Here, the realization of such a concept is investigated using an oscillating incident beam produced via a precession method and a secondary spectrometer identical to a BS instrument using crystal analyzers. The instrument is denoted "Modulated Intensity with Diffraction Analysis Spectrometer" (MIDAS). However, simpler approaches, e.g., choppers, may also be used for an FTNS instrument. The theory behind MIDAS is presented, supported by numerical calculations and in silico experiments. Finally, we present a Monte Carlo simulation to compare BS and MIDAS spectrometers. This shows that MIDAS has almost 100 times more incident flux than standard BS, but due to the better signal-to-noise ratio of BS, the final information acquisition rate gain of MIDAS is approximately a factor of 2.

Sudden Visual Loss due to Arteritic Anterior Ischaemic Optic Neuropathy: A Rare Manifestation of Eosinophilic Granulomatosis with Polyangiitis.

Background: eosinophilic granulomatosis with polyangiitis (EGPA) is a rare multisystem inflammatory disease characterized by asthma, eosinophilia and granulomatous or vasculitic involvement of various organs. While the eye is uncommonly affected in patients with EGPA, multiple ophthalmic manifestations have been reported, which can result in serious visual impairment without timely treatment. Case report: we report the case of a 79-year-old woman with a history of asthma and nasal polyps who presented with low-grade fever, mild alteration of mental status, and fatigue. Chest X-ray revealed bilateral interstitial infiltrates. Lab tests showed elevated C-reactive protein level and eosinophilia (eosinophil count, 4.6 x109 cells/l); blood cultures and parasitological examination of stools tested negative. Four days after presentation, the patient reported sudden and severe blurring of vision in her left eye. Ophthalmological examination revealed bilateral swollen optic disc and visual field loss, more severe in the left eye. A diagnosis of EGPA complicated by arteritic anterior ischaemic optic neuropathy (A-AION) was proposed, while an alternative or concurrent diagnosis of giant cell arteritis was ruled out based on clinical picture. Immunosuppressive treatment with high-dose intravenous glucocorticoids was promptly started. The patient's visual defect did not improve; however, two months later, no worsening was registered on ophthalmic reassessment. Conclusions: A-AION is an infrequent but severe manifestation of EGPA, requiring prompt diagnosis and emergency-level glucocorticoid therapy to prevent any further vision loss. Disease awareness and a multidisciplinary approach are crucial to expedite diagnostic work-up and effective management of EGPA-related ocular complications. LEARNING POINTS: Arteritic ischaemic optical neuropathy is a potential cause of sudden and severe visual loss in eosinophilic granulomatosis with polyangiitis (EGPA) patients.Visual loss due to arteritic ischaemic optical neuropathy is rarely reversible; however, a timely glucocorticoid treatment may prevent further progression of visual impairment.Multidisciplinary approach is crucial to expedite diagnostic work-up and effective management of EGPA patients with ocular complications.

Neutron spin echo spectroscopy with a moving sample.

Neutron spin echo spectroscopy is a high resolution inelastic neutron scattering method probing nanosecond dynamics. It is well suited to study the atomistic motion in polymer systems and contributes to our understanding of viscoelasticity. However, for samples under shear, or moving samples in general, Doppler scattering has to be considered. We compare the measured phase shift and depolarisation due to Doppler scattering from a rotating graphite disk to numerical and analytical calculations and find excellent agreement. This allows to take into account Doppler scattering during the data processing and makes longer Fourier times as well as higher shear rates and Q ranges possible with neutron spin echo spectroscopy, enabling for example the study of polymers under high shear.

Clinical utility of circulating calprotectin to assist prediction and monitoring of COVID-19 severity: An Italian study.

BACKGROUND: Calprotectin (S100A8/A9) has been identified as a biomarker that can aid in predicting the severity of disease in COVID-19 patients. This study aims to evaluate the correlation between levels of circulating calprotectin (cCP) and the severity of COVID-19. METHODS: Sera from 245 COVID-19 patients and 110 apparently healthy individuals were tested for calprotectin levels using a chemiluminescent immunoassay (Inova Diagnostics). Intensive care unit (ICU) admission and type of respiratory support administered were used as indicators of disease severity, and their correlation with calprotectin levels was assessed. RESULTS: Samples from patients in the ICU had a median calprotectin concentration of 11.6 µg/ml as compared to 3.5 µg/ml from COVID-19 patients who were not in the ICU. The median calprotectin concentration in a cohort of healthy individuals collected before the COVID-19 pandemic was 3.0 µg/ml (95% CI: 2.820-2.969 µg/ml). Patients requiring a Venturi mask, continuous positive airway pressure, or orotracheal intubation all had significantly higher values of calprotectin than controls, with the increase of cCP levels proportional to the increasing need of respiratory support. CONCLUSION: Calprotectin levels in serum correlate well with disease severity and represent a promising serological biomarker for the risk assessment of COVID-19 patients.

EXPANSE: A time-of-flight EXPanded Angle Neutron Spin Echo spectrometer at the Second Target Station of the Spallation Neutron Source.

EXPANSE, an EXPanded Angle Neutron Spin Echo instrument, has been proposed and selected as one of the first suite of instruments to be built at the Second Target Station of the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is designed to address scientific problems that involve high-energy resolution (neV-µeV) of dynamic processes in a wide range of materials. The wide-angle detector banks of EXPANSE provide coverage of nearly two orders of magnitude in scattering wavenumbers, and the wide wavelength band affords approximately four orders of magnitude in Fourier times. This instrument will offer unique capabilities that are not available in the currently existing neutron scattering instruments in the United States. Specifically, EXPANSE will enable direct measurements of slow dynamics in the time domain over wide Q-ranges simultaneously and will also enable time-resolved spectroscopic studies. The instrument is expected to contribute to a diverse range of science areas, including soft matter, polymers, biological materials, liquids and glasses, energy materials, unconventional magnets, and quantum materials.

Electrostatic Repulsion Slows Relaxations of Polyelectrolytes in Semidilute Solutions.

We investigate the structure and dynamics of unentangled semidilute solutions of sodium polystyrenesulfonate (NaPSS) using small-angle neutron scattering (SANS) and neutron spin-echo (NSE) spectroscopy. The effects of electrostatic interactions and chain structure are examined as a function of ionic strength and polymer concentration, respectively. The SANS profiles exhibit a characteristic structural peak, signature of polyelectrolyte solutions, that can be fit with a combination of a semiflexible chain with excluded volume interactions form factor and a polymer reference interaction site model (PRISM) structure factor. We confirm that electrostatic interactions vary with ionic strength across solutions with similar geometries. The segmental relaxations from NSE deviate from theoretical predictions from Zimm and exhibit two scaling behaviors, with the crossover between the two regimes taking place around the characteristic structural peak. The chain dynamics are suppressed across the length scale of the correlation blob, and inversely related to the structure factor. These observations suggest that the highly correlated nature of polyelectrolytes presents an additional energy barrier that leads to de Gennes narrowing behavior.

Q-dependent collective relaxation dynamics of glass-forming liquid Ca0.4K0.6(NO3)1.4 investigated by wide-angle neutron spin-echo.

The relaxation behavior of glass formers exhibits spatial heterogeneity and dramatically changes upon cooling towards the glass transition. However, the underlying mechanisms of the dynamics at different microscopic length scales are not fully understood. Employing the recently developed wide-angle neutron spin-echo spectroscopy technique, we measured the Q-dependent coherent intermediate scattering function of a prototypical ionic glass former Ca0.4K0.6(NO3)1.4, in the highly viscous liquid state. In contrast to the structure modulated dynamics for Q < 2.4 Å-1, i.e., at and below the structure factor main peak, for Q > 2.4 Å-1, beyond the first minimum above the structure factor main peak, the stretching exponent exhibits no temperature dependence and concomitantly the relaxation time shows smaller deviations from Arrhenius behavior. This finding indicates a change in the dominant relaxation mechanisms around a characteristic length of 2π/(2.4 Å-1) ≈ 2.6 Å, below which the relaxation process exhibits a temperature independent distribution and more Arrhenius-like behavior.

Predictors of poor outcome in tocilizumab treated patients with Sars-CoV-2 related severe respiratory failure: A multicentre real world study.

INTRODUCTION: Despite Tocilizumab is now recognized as a concrete therapeutic option in patients with severe SARS-CoV-2 related respiratory failure, literature lacks about factors influencing the response to it in this context. Therefore, the aim of our study was to provide evidence about predictors of poor outcome in Tocilizumab treated patients in the real-world practice. MATERIALS AND METHODS: We retrospectively analyzed clinical, laboratory and chest computer tomography (CCT) data of patients firstly admitted in non Intensive Care Units (ICU) and suffering from severe respiratory failure, who were treated with the IL-6 antagonist Tocilizumab. We compared patients who died and/or required admission to ICU with oro-tracheal intubation (OTI) with those who did not. RESULTS: Two hundreds and eighty-seven patients (29.9% females) with mean age ± SD 64.1 ± 12.6 years were the study population. In-hospital mortality was 18.8%, while the composite endpoint in-hospital mortality and/or ICU admission with OTI occurred in 23.7%. At univariate analysis, patients who died and/or were admitted to ICU with OTI were significantly older and co-morbid, had significantly higher values of creatinine, C-reactive protein (CRP) and procalcitonin and lower lymphocytes count, PaO2/FiO2 ratio (P/F) and room air pulsossimetry oxygen saturation (RAO2S) at hospital admission. Computed tomography ground glass opacities (CT-GGO) involving the pulmonary surface ≥ 50% were found in 55.4% of patients who died and/or were admitted to ICU with OTI and in 21.5% of patients who did not (p=0.0001). At multivariate analysis, age ≥ 65 years (OR 17.3, 95% CI: 3.7-81.0), procalcitonin ≥ 0.14 (OR 9.9, 95%CI: 1.7-56.1), RAO2S ≤ 90% (OR 4.6, 95%CI: 1.2-17.0) and CCT-GGO involvement ≥ 50% (OR 5.1, 95%CI: 1.2-21.0) were independent risk factors associated with death and/or ICU admission with OTI. CONCLUSION: Tocilizumab has shown to improve outcome in patients with severe respiratory failure associated to SARS-CoV-2 related pneumonia. In our multicentre study focusing on Tocilizumab treated severe COVID-19 patients, age ≥ 65 years, procalcitonin ≥ 0.14 ng/mL, RAO2S ≤ 90% and CCT-GGO involvement ≥ 50% were independent factors associated with poor outcome.

Dynamics of molecular associates in methanol/water mixtures.

The dynamics of molecular associates in a methanol/water mixture was investigated using quasielastic neutron scattering. By measuring the signal from four methanol/water samples differing only by their isotopic composition, the relative motion of the water to methanol molecules, i.e. their mutual dynamics, was determined at the nanoscale. The thus obtained nanoscopic mutual diffusion coefficient signals a significantly slower process than the single particle diffusion of either methanol or water in the system as well as their macroscopic mutual diffusion. The data do not provide any indication of microsegregation in this preeminent alcohol/water mixture; however, they do indicate the existence of long lived but dynamic molecular associates of water and methanol molecules. Analysis of the structural relaxation shows that the lifetime of molecular association through hydrogen bonding determines the fact that viscosity of the mixtures at intermediate concentrations is higher than that of both pure components.

One-year evolution of DLCO changes and respiratory symptoms in patients with post COVID-19 respiratory syndrome.

PURPOSE: During a follow-up program of patients admitted for COVID-19 at our non-ICU Unit, we found that 37% of them had decreased diffusing lung capacity for carbon monoxide (DLCO) 3-6 months after discharge. This prospective observational study aimed to evaluate the evolution of changes in DLCO and respiratory symptoms at the 1-year follow-up visit. METHODS: Seventeen (mean age 71 years; 8 males) of 19 eligible patients (DLCO < 80% of predicted at the 3-6 months follow-up visit) completed the 1-year follow-up visit. One patient refused to participate and 1 patient had died 3 months earlier from myocardial infarction. The visit included a self-reported structured questionnaire, physical exam, blood tests, ECG, and spirometry with DLCO. RESULTS: Mean DLCO was significantly improved at the 1-year visit (from 64% of predicted at 3-6 months to 74% of predicted at 1 year; P = 0.003). A clinically significant increase in DLCO (10% or greater) was observed in 11 patients (65%) with complete normalization (> 80% of predicted) in 6 (35%); in the other 6 (35%) it remained unchanged. The prevalence of exertional dyspnea (65-35%, P = 0.17), cough (24-18%, P = 1), and fatigue (76-35%, P = 0.04) decreased at the 1-year visit. CONCLUSION: These results suggest that DLCO and respiratory symptoms tend to normalize or improve 1 year after hospitalization for COVID-19 in most patients. However, there is also a non-negligible number of patients (about one-third) in whom respiratory changes persist and will need prolonged follow-up.

Colloid-like solution behavior of computationally designed coiled coil bundlemers.

The use of isotropic potential models of simple colloids for describing complex protein-protein interactions is a topic of ongoing debate in the biophysical community. This contention stems from the unavailability of synthetic protein-like model particles that are amenable to systematic experimental characterization. In this article, we test the utility of colloidal theory to capture the solution structure, interactions and dynamics of novel globular protein-mimicking, computationally designed peptide assemblies called bundlemers that are programmable model systems at the intersection of colloids and proteins. Small-angle neutron scattering (SANS) measurements of semi-dilute bundlemer solutions in low and high ionic strength solution indicate that bundlemers interact locally via repulsive interactions that can be described by a screened repulsive potential. We also present neutron spin echo (NSE) spectroscopy results that show high-Q freely-diffusive dynamics of bundlemers. Importantly, formation of clusters due to short-range attractive, inter-bundlemer interactions is observed in SANS even at dilute bundlemer concentrations, which is indicative of the complexity of the bundlemer charged surface. The similarities and differences between bundlemers and simple colloidal as well as complex protein-protein interactions is discussed in detail.

Course and Lethality of SARS-CoV-2 Epidemic in Nursing Homes after Vaccination in Florence, Italy.

Evidence on the effectiveness of SARS-CoV-2 vaccines in nursing home (NHs) residents is limited. We examined the impact of the BNT162b2 mRNA SARS-CoV-2 vaccine on the course of the epidemic in NHs in the Florence Health District, Italy, before and after vaccination. Moreover, we assessed survival and hospitalization by vaccination status in SARS-CoV-2-positive cases occurring during the post-vaccination period. We calculated the weekly infection rates during the pre-vaccination (1 October-26 December 2020) and post-vaccination period (27 December 2020-31 March 2021). Cox analysis was used to analyze survival by vaccination status. The study involved 3730 residents (mean age 84, 69% female). Weekly infection rates fluctuated during the pre-vaccination period (1.8%-6.5%) and dropped to zero during the post-vaccination period. Nine unvaccinated (UN), 56 partially vaccinated (PV) and 35 fully vaccinated (FV) residents tested SARS-CoV-2+ during the post-vaccination period. FV showed significantly lower hospitalization and mortality rates than PV and UV (hospitalization: FV 3%, PV 14%, UV 33%; mortality: FV 6%, PV 18%, UV 56%). The death risk was 84% and 96% lower in PV (HR 0.157, 95%CI 0.049-0.491) and FV (HR 0.037, 95%CI 0.006-0.223) versus UV. SARS-CoV-2 vaccination was followed by a marked decline in infection rates and was associated with lower morbidity and mortality among infected NH residents.

Caring for nursing home residents with COVID-19: a "hospital-at-nursing home" intermediate care intervention.

BACKGROUND: Nursing home (NH) residents have been dramatically affected by COVID-19, with extremely high rates of hospitalization and mortality. AIMS: To describe the features and impact of an assistance model involving an intermediate care mobile medical specialist team (GIROT, Gruppo Intervento Rapido Ospedale Territorio) aimed at delivering "hospital-at-nursing home" care to NH residents with COVID-19 in Florence, Italy. METHODS: The GIROT activity was set-up during the first wave of the pandemic (W1, March-April 2020) and became a structured healthcare model during the second (W2, October 2020-January 2021). The activity involved (1) infection transmission control among NHs residents and staff, (2) comprehensive geriatric assessment including prognostication and geriatric syndromes management, (3) on-site diagnostic assessment and protocol-based treatment of COVID-19, (4) supply of nursing personnel to understaffed NHs. To estimate the impact of the GIROT intervention, we reported hospitalization and infection lethality rates recorded in SARS-CoV-2-positive NH residents during W1 and W2. RESULTS: The GIROT activity involved 21 NHs (1159 residents) and 43 NHs (2448 residents) during W1 and W2, respectively. The percentage of infected residents was higher in W2 than in W1 (64.5% vs. 38.8%), while both hospitalization and lethality rates significantly decreased in W2 compared to W1 (10.1% vs 58.2% and 23.4% vs 31.1%, respectively). DISCUSSION: Potentiating on-site care in the NHs paralleled a decrease of hospital admissions with no increase of lethality. CONCLUSIONS: An innovative "hospital-at-nursing home" patient-centred care model based on comprehensive geriatric assessment may provide a valuable contribution in fighting COVID-19 in NH residents.

Relationship between Viscosity and Acyl Tail Dynamics in Lipid Bilayers.

Membrane viscosity is a fundamental property that controls molecular transport and structural rearrangements in lipid membranes. Given its importance in many cell processes, various experimental and computational methods have been developed to measure the membrane viscosity, yet the estimated values depend highly on the method and vary by orders of magnitude. Here we investigate the molecular origins of membrane viscosity by measuring the nanoscale dynamics of the lipid acyl tails using x-ray and neutron spectroscopy techniques. The results show that the membrane viscosity can be estimated from the structural relaxation times of the lipid tails.

Admission Braden Scale Score as an Early Independent Predictor of In-Hospital Mortality Among Inpatients With COVID-19: A Retrospective Cohort Study.

BACKGROUND: The COVID-19 pandemic has put a strain on health systems. Predictors of adverse outcomes need to be investigated to properly manage COVID-19 patients. The Braden Scale (BS), commonly used for the assessment of pressure ulcer risk, has recently been proposed to identify frailty. OBJECTIVE: To investigate the predictive utility of the BS for prediction of in-hospital mortality in a cohort of COVID-19 patients admitted to non-ICU wards. METHODS: We conducted a retrospective single-center cohort study evaluating all patients with SARS-CoV-2 infection consecutively admitted over a 2-month period (from March 6 to May 7, 2020) to the COVID-19 general wards of our institution. Demographic, clinical, and nursing assessment data, including admission BS, were extracted from electronic medical records. Univariable and multivariable logistic regression models were used to explore the association between the BS score and in-hospital death. RESULTS: Braden Scale was assessed in 146 patients (mean age 74.7 years; 52% males). On admission, 46 had a BS ≤ 15, and 100 patients had a BS > 15. Mortality among patients with BS ≤ 15 was significantly higher than in patients with BS > 15 (45.7% vs. 16%; p < .001). On multivariable regression analysis, adjusting for potentials confounders (age, Barthel scale, chronic kidney disease, atrial fibrillation, and hypertension), the admission BS remained inversely associated with the risk of in-hospital mortality (OR = 0.76; 95% CI [0.60, 0.96]; p = .020). LINKING EVIDENCE TO ACTION: Admission BS could be used as a simple bedside predictive tool able to early identify non-ICU COVID-19 patients with poor prognosis who might benefit from specific and timely interventions.

Stiffening Effect of the [Bmim][Cl] Ionic Liquid on the Bending Dynamics of DMPC Lipid Vesicles.

The elastic properties of the cellular lipid membrane play a crucial role for life. Their alteration can lead to cell malfunction, and in turn, being able to control them holds the promise of effective therapeutic and diagnostic approaches. In this context, due to their proven strong interaction with lipid bilayers, ionic liquids (ILs)-a vast class of organic electrolytes-may play an important role. This work focuses on the effect of the model imidazolium-IL [bmim][Cl] on the bending modulus of DMPC lipid vesicles, a basic model of cellular lipid membranes. Here, by combining small-angle neutron scattering and neutron spin-echo spectroscopy, we show that the IL, dispersed at low concentrations at the bilayer-water interface, (i) diffuses into the lipid region, accounting for five IL-cations for every 11 lipids, and (ii) causes an increase of the lipid bilayer bending modulus, up to 60% compared to the neat lipid bilayer at 40 °C.

COVID-19: persistence of symptoms and lung alterations after 3-6 months from hospital discharge.

PURPOSE: Few data are currently available on persistent symptoms and late organ damage in patients who have suffered from COVID-19. This prospective study aimed to evaluate the results of a follow-up program for patients discharged from a nonintensive COVID-19 ward. METHODS: 3-6 months after hospital discharge, 59 of 105 COVID-19 patients (31 males, aged 68.2 ± 12.8 years) were recruited in the study. Forty-six patients were excluded because of nontraceability, refusal, or inability to provide informed consent. The follow-up consisted of anamnesis (including a structured questionnaire), physical examination, blood tests, ECG, lower limb compression venous ultrasound (US), thoracic US, and spirometry with diffusion lung capacity for carbon monoxide (DLCO). RESULTS: 22% of patients reported no residual symptoms, 28.8% 1 or 2 symptoms and 49.2% 3 or more symptoms. The most frequently symptoms were fatigue, exertional dyspnea, insomnia, and anxiety. Among the inflammatory and coagulation parameters, only the median value of fibrinogen was slightly above normal. A deep vein thrombosis was detected in 1 patient (1.7%). Thoracic US detected mild pulmonary changes in 15 patients (25.4%), 10 of which reported exertional dyspnea. DLCO was mildly or moderately reduced in 19 patients (37.2%), 13 of which complained of exertional dyspnea. CONCLUSION: These results highlight that a substantial percentage of COVID-19 patients (77.8%) continue to complain of symptoms 3-6 months after hospital discharge. Exertional dyspnea was significantly associated with the persistence of lung US abnormalities and diffusing capacity alterations. Extended follow-up is required to assess the long-term evolution of postacute sequelae of COVID-19.

Incidence of deep vein thrombosis through an ultrasound surveillance protocol in patients with COVID-19 pneumonia in non-ICU setting: A multicenter prospective study.

OBJECTIVE: The aim of this study was to assess the incidence of deep vein thrombosis (DVT) of the lower limbs, using serial compression ultrasound (CUS) surveillance, in acutely ill patients with COVID-19 pneumonia admitted to a non-ICU setting. METHODS: Multicenter, prospective study of patients with COVID-19 pneumonia admitted to Internal Medicine units. All patients were screened for DVT of the lower limbs with serial CUS. Anticoagulation was defined as: low dose (enoxaparin 20-40 mg/day or fondaparinux 1.5-2.5 mg/day); intermediate dose (enoxaparin 60-80 mg/day); high dose (enoxaparin 120-160 mg or fondaparinux 5-10 mg/day or oral anticoagulation). The primary end-point of the study was the diagnosis of DVT by CUS. RESULTS: Over a two-month period, 227 consecutive patients with moderate-severe COVID-19 pneumonia were enrolled. The incidence of DVT was 13.7% (6.2% proximal, 7.5% distal), mostly asymptomatic. All patients received anticoagulation (enoxaparin 95.6%) at the following doses: low 57.3%, intermediate 22.9%, high 19.8%. Patients with and without DVT had similar characteristics, and no difference in anticoagulant regimen was observed. DVT patients were older (mean 77±9.6 vs 71±13.1 years; p = 0.042) and had higher peak D-dimer levels (5403 vs 1723 ng/mL; p = 0.004). At ROC analysis peak D-dimer level >2000 ng/mL (AUC 0.703; 95% CI 0.572-0.834; p = 0.004) was the most accurate cut-off value able to predict DVT (RR 3.74; 95%CI 1.27-10, p = 0.016). CONCLUSIONS: The incidence of DVT in acutely ill patients with COVID-19 pneumonia is relevant. A surveillance protocol by serial CUS of the lower limbs is useful to timely identify DVT that would go otherwise largely undetected.

Relevance of hydrogen bonded associates to the transport properties and nanoscale dynamics of liquid and supercooled 2-propanol.

2-Propanol was investigated, in both the liquid and supercooled states, as a model system to study how hydrogen bonds affect the structural relaxation and the dynamics of mesoscale structures, of approximately several Ångstroms, employing static and quasi-elastic neutron scattering and molecular dynamics simulation. Dynamic neutron scattering measurements were performed over an exchanged wave-vector range encompassing the pre-peak, indicative of the presence of H-bonding associates, and the main peak. The dynamics observed at the pre-peak is associated with the formation and disaggregation of the H-bonded associates and is measured to be at least one order of magnitude slower than the dynamics at the main peak, which is identified as the structural relaxation. The measurements indicate that the macroscopic shear viscosity has a similar temperature dependence as the dynamics of the H-bonded associates, which highlights the important role played by these structures, together with the structural relaxation, in defining the macroscopic rheological properties of the system. Importantly, the characteristic relaxation time at the pre-peak follows an Arrhenius temperature dependence whereas at the main peak it exhibits a non-Arrhenius behavior on approaching the supercooled state. The origin of this differing behavior is attributed to an increased structuring of the hydrophobic domains of 2-propanol accommodating a more and more encompassing H-bond network, and a consequent set in of dynamic cooperativity.