Using uniaxial stress to probe the relationship between competing superconducting states in a cuprate with spin-stripe order

We report muon spin rotation and magnetic susceptibility experiments on in-plane stress effects on the static spin-stripe order and superconductivity in the cuprate system La2-xBaxCuO4 with x = 0.115. An extremely low uniaxial stress of 0.1 GPa induces a substantial decrease in the magnetic volume fraction and a dramatic rise in the onset of 3D superconductivity, from 10 to 32 K; however, the onset of at-least-2D superconductivity is much less sensitive to stress. These results show not only that large-volume-fraction spin-stripe order is anti-correlated with 3D superconducting (SC) coherence, but also that these states are energetically very finely balanced. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. These results strongly suggest a similar pairing mechanism for spin-stripe order, the spatially-modulated 2D and uniform 3D SC orders, imposing an important constraint on theoretical models.Comment: To appear in Physical Review Letters (2020

Designing the stripe-ordered cuprate phase diagram through uniaxial-stress

The ability to efficiently control charge and spin in the cuprate high-temperature superconductors is crucial for fundamental research and underpins technological development. Here, we explore the tunability of magnetism, superconductivity and crystal structure in the stripe phase of the cuprate La_2-xBa_xCuO_4, with x = 0.115 and 0.135, by employing temperature-dependent (down to 400 mK) muon-spin rotation and AC susceptibility, as well as X-ray scattering experiments under compressive uniaxial stress in the CuO_2 plane. A sixfold increase of the 3-dimensional (3D) superconducting critical temperature T_c and a full recovery of the 3D phase coherence is observed in both samples with the application of extremely low uniaxial stress of 0.1 GPa. This finding demonstrates the removal of the well-known 1/8-anomaly of cuprates by uniaxial stress. On the other hand, the spin-stripe order temperature as well as the magnetic fraction at 400 mK show only a modest decrease under stress. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. However, a substantial decrease of the magnetic volume fraction and a full suppression of the low-temperature tetragonal structure is found at elevated temperatures, which is a necessary condition for the development of the 3D superconducting phase with optimal T_c. Our results evidence a remarkable cooperation between the long-range static spin-stripe order and the underlying crystalline order with the three-dimensional fully coherent superconductivity. Overall, these results suggest that the stripe- and the SC order may have a common physical mechanism.Comment: 11 pages, 5 figures. This work builds on our earlier findings on LBCO, arXiv:2008.01159, and substantially expands i

Facile formation of highly mobile supported lipid bilayers on surface-quaternized pH-responsive polymer brushes

Poly(2-dimethylamino)ethyl methacrylate) (PDMA) brushes are grown from planar substrates via surface atom transfer radical polymerization (ATRP). Quaternization of these brushes is conducted using 1-iodooctadecane in n-hexane, which is a non-solvent for PDMA. Ellipsometry, AFM, and water contact angle measurements show that surface-confined quaternization occurs under these conditions, producing pH-responsive brushes that have a hydrophobic upper surface. Systematic variation of the 1-iodooctadecane concentration and reaction time enables the mean degree of surface quaternization to be optimized. Relatively low degrees of surface quaternization (ca. 10 mol % as judged by XPS) produce brushes that enable the formation of supported lipid bilayers, with the hydrophobic pendent octadecyl groups promoting in situ rupture of lipid vesicles. Control experiments confirm that quaternized PDMA brushes prepared in a good brush solvent (THF) produce non-pH-responsive brushes, presumably because the pendent octadecyl groups form micelle-like physical cross-links throughout the brush layer. Supported lipid bilayers (SLBs) can also be formed on the non-quaternized PDMA precursor brushes, but such structures proved to be unstable to small changes in pH. Thus, surface quaternization of PDMA brushes using 1-iodooctadecane in n-hexane provides the best protocol for the formation of robust SLBs. Fluorescence recovery after photobleaching (FRAP) studies of such SLBs indicate diffusion coefficients (2.8 ± 0.3 μm s–1) and mobile fractions (98 ± 2%) that are comparable to the literature data reported for SLBs prepared directly on planar glass substrates

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Findings From the MATREX Study:A Treatment Protocol for the Delivery of Manual Chest Therapy in Respiratory Care

One of the difficulties in comparing the numerous studies on manual chest therapy (MCT) is the wide variety of techniques used and terms employed to describe the intervention. This lack of consistency in therapeutic approach and the absence of defined tools for evaluation have led to a continued air of skepticism about its true value. This paper presents a treatment protocol used in a large randomized controlled trial examining the efficacy and cost effectiveness of MCT for patients hospitalized with exacerbations of COPD. METHODS: Consensus development meetings with key physical therapists were held to identify the essential elements of MCT, address potential areas of ambiguity, and provide a set of clear parameters within which treatment would be based and recorded. This iterative approach resulted in a treatment protocol that combined best clinical practice with the research evidence available to date. RESULTS: In the Management of Exacerbations of COPD (MATREX) trial, 658 sessions of MCT were delivered by physical therapists over a 3 year period. A high level of adherence to the treatment protocol was seen for all but one of the protocol elements. CONCLUSIONS: With respect to the essential elements of MCT, the treatment protocol used in the MATREX trial offers sufficient flexibility to the therapist, while being robust enough to maintain clinical trial integrity. The level of adherence by therapists indicates its professional acceptability with respect to delivering and evaluating this therapy

Comparison of hydrocellular foam and calcium alginate in the healing and comfort of split-thickness skin-graft donor sites

This is a comparative study of a hydrocellular foam (Allevyn, Smith and Nephew) and a calcium alginate (Kaltostat, ConvaTec) in dressing split-thickness skin-graft donor sites. The dressing materials were used in equal halves of each donor site in 20 patients undergoing skin-graft harvest. </jats:p

Effect of ozone, thunderstorms and other weather conditions on the respiratory function of asthmatics

There is concern that exposure to the air pollutant ozone may adversely affect respiratory function. Ozone is formed photochemically by the action of sunlight on pre-cursor pollutants and peak concentrations usually occur during spells of hot sunny weather in summer. There is also evidence that summer thunderstorms may exacerbate asthma. In order to investigate the possible effects of ozone and summer weather conditions on asthma a panel of 29 patients was recruited from outpatients from a hospital asthma clinic in Norfolk. Daily morning peak-flow measurements (pre-medication) were analysed for June, July and August 1994. For each subject the daily measurements were expressed as the percentage of their best peak-flow and the average for the whole panel was then calculated. Daily ozone measurements from the national air pollution monitoring site at Sibton and data on weather conditions in Norwich were also collected. Multiple regression analysis was used to examine the association between daily peak flow, ozone and a number of weather variables, including the occurrence of thunderstorms, with lags of up to 5 days. A significant positive association (p<0.001) was found between peak flow and temperature over the previous 3 days. Peak flow was significantly negatively associated with the number of days with thunder in the previous 5 days (p=<0.001), the number of days with poor ozone (at or above 90 ppb) in the last 3 days (p<0.001) and the number of days with rain in the last 4 days (p<0.001). These 4 variables explained 48% of the variance in daily peak flow. The model estimate is that each day of poor ozone is associated with a change in peak flow (as % of best) of -1.07 (95% c.i. -1.52, -0.63) and each day with thunder -0.70 (95% c.i. -0.98, -0.43). During the summer period studied there was therefore evidence of small, but statistically significant adverse effects of ozone, thunderstorms and wet weather on the respiratory function of asthmatics in Norfolk