Hygroscopic Behavior of NaCl-Bearing Natural Aerosol Particles Using Environmental Transmission Electron Microscopy

We used conventional and environmental transmission electron microscopes to determine morphology, composition, and water uptake of individual natural inorganic aerosol particles collected from industrial pollution plumes and from clean and polluted marine environments. Five particle types are described in detail. They range from relatively insoluble mineral grains to internally mixed particles containing NaCl with other soluble or relatively insoluble material. We studied the hygroscopic behavior of these particles from 0 to 100% relative humidity (RH). Relatively insoluble materials do not take up water over the experimental RH range. Single crystals of NaCl from both natural and laboratory sources have a well-defined deliquescence point of approximately 76% RH at 291 K. NaCl-bearing aggregate particles appear to deliquesce between 74 and 76% RH (same RH within error) when NaCl is internally mixed with relatively insoluble phases, but the particles deliquesce at lower RH when aggregated with other soluble phases such as NaNO3. For all NaCl-bearing particles studied, hygroscopic growth is pronounced above 76% RH, and water uptake by the particles is dominated by the soluble phase. Furthermore, the soluble phase initiating deliquescence controls the locus of further hygroscopic growth of the aggregate particle. Our results demonstrate that composition and mixing state affect water uptake of natural aerosol particles. Furthermore, internally mixed particles are confirmed to deliquesce at lower RH values than predicted from the individual components

Hygroscopic Behavior and Liquid-Layer Composition of Aerosol Particles Generated from Natural and Artificial Seawater

Sea-salt aerosol (SSA) particles affect the Earth\u27s radiative balance and moderate heterogeneous chemistry in the marine boundary layer. Using conventional and environmental transmission electron microscopes (ETEM), we investigated the hygroscopic growth and liquid-layer compositions of particles generated from three types of aqueous salt solutions: sodium chloride, laboratory-synthesized seawater (S-SSA particles), and natural seawater (N-SSA particles). Three levels of morphological change were observed with the ETEM as the laboratory-generated particles were exposed to increasing relative humidity (RH). The first level, onset of observable morphological changes, occurred on average at 70, 48, and 35% RH for the NaCl, S-SSA, and N-SSA particles, respectively. The second level, rounding, occurred at 74, 66, and 57% RH for NaCl, S-SSA, and N-SSA particles, respectively. The third level, complete deliquescence, occurred at 75% RH for all particles. Collected ambient SSA particles were also examined. With the exception of deliquescence, they did not exhibit the same hygroscopic characteristics as the NaCl particles. The ambient particles, however, behaved most similarly to the synthesized and natural SSA particles, although the onset of morphological change was slightly higher for the S-SSA particles. We used energy-dispersive X-ray spectrometry to study the composition of the liquid layer formed on the S-SSA and N-SSA particles. The layer was enriched in Mg, S, and O relative to the solid particle core. An important implication of these results is that MgSO4-enriched solutions on the surface of SSA particles may be the solvents of many heterogeneous reactions

Comparison of foam swabs and toothbrushes as oral hygiene interventions in mechanically ventilated patients: a randomised split mouth study

Abstract Introduction During critical illness, dental plaque may serve as a reservoir of respiratory pathogens. This study compared the effectiveness of toothbrushing with a small-headed toothbrush or a foam-headed swab in mechanically ventilated patients. Methods This was a randomised, assessor-blinded, split-mouth trial, performed at a single critical care unit. Adult, orally intubated patients with >20 teeth, where >24 hours of mechanical ventilation was expected were included. Teeth were cleaned 12-hourly using a foam swab or toothbrush (each randomly assigned to one side of the mouth). Cleaning efficacy was based on plaque scores, gingival index and microbial plaque counts. Results High initial plaque (mean=2.1 (SD 0.45)) and gingival (mean=2.0 (SD 0.54)) scores were recorded for 21 patients. A significant reduction compared with initial plaque index occurred using both toothbrushes (mean change=−1.26, 95% CI −1.57 to −0.95; p<0.001) and foam swabs (mean change=−1.28, 95% CI −1.54 to −1.01; p<0.001). There was significant reduction in gingival index over time using toothbrushes (mean change=−0.92; 95% CI −1.19 to −0.64; p<0.001) and foam swabs (mean change=−0.85; 95% CI −1.10 to −0.61; p<0.001). Differences between cleaning methods were not statistically significant (p=0.12 for change in gingival index; p=0.24 for change in plaque index). There was no significant change in bacterial dental plaque counts between toothbrushing (mean change 3.7×104 colony-forming units (CFUs); minimum to maximum (−2.5×1010 CFUs, 8.7×107 CFUs)) and foam swabs (mean change 9×104 CFUs; minimum to maximum (−3.1×1010 CFUs, 3.0×107 CFUs)). Conclusions Patients admitted to adult intensive care had poor oral health, which improved after brushing with a toothbrush or foam swab. Both interventions were equally effective at removing plaque and reducing gingival inflammation. Trial registration number NCT01154257; Pre-results

Hygroscopic behavior of aerosol particles from biomass fires using environmental transmission electron microscopy

Abstract We used both a conventional transmission electron microscope and an environmental transmission electron microscope (ETEM) to determine morphology, composition, and water uptake of 80 individual aerosol particles collected from the young smoke of flaming and smoldering fires during SAFARI-2000, a comprehensive air quality campaign in southern Africa. Six representative carbonaceous particle types are described, including soot, tar balls, and heterogeneously internally mixed particles containing C with S-, K-, Mg-or Narich inorganic phases. The hygroscopic behavior of these particles over the range 0-100% relative humidity (RH) was studied in detail. Soot and tar balls did not take up water, whereas the mixed organic-inorganic particles took up water between 55 and 100% RH, the exact value depending on the composition of their water-soluble phases. The inorganic phase appeared to determine the hygroscopic properties of all mixed organic-inorganic particles. Thus, incorporation of inorganic plant material or reactions with inorganic atmospheric components can dramatically alter the hygroscopic properties of carbonaceous particles in smoke plumes. The fraction of these mixed organic-inorganic particles plausibly increases with time, which will modulate the effects of smoke on radiative budgets

GRACKLE: a chemistry and cooling library for astrophysics

We present the Grackle chemistry and cooling library for astrophysical simulations and models. Grackle provides a treatment of non-equilibrium primordial chemistry and cooling for H, D, and He species, including H2 formation on dust grains; tabulated primordial and metal cooling; multiple UV background models; and support for radiation transfer and arbitrary heat sources. The library has an easily implementable interface for simulation codes written in C, C++, and Fortran as well as a Python interface with added convenience functions for semi-analytical models. As an open-source project, Grackle provides a community resource for accessing and disseminating astrochemical data and numerical methods. We present the full details of the core functionality, the simulation and Python interfaces, testing infrastructure, performance, and range of applicability. Grackle is a fully open-source project and new contributions are welcome.Comment: 20 pages, 8 figures, accepted for publication in MNRAS. For more info, visit grackle.readthedocs.i

A randomized trial of the efficacy and safety of sequential intravenous/oral moxifloxacin monotherapy versus intravenous piperacillin/tazobactam followed by oral amoxicillin/clavulanate for complicated skin and skin structure infections

Item does not contain fulltextOBJECTIVES: The primary aim of the RELIEF study was to evaluate the efficacy and safety of two sequential intravenous (iv)/oral regimens: moxifloxacin iv/oral versus piperacillin/tazobactam (TZP) iv followed by oral amoxicillin/clavulanate (AMC). PATIENTS AND METHODS: The study had a prospective, randomized, double-dummy, double-blind, multicentre design. Patients >/=18 years were prospectively stratified according to complicated skin and skin structure infection (cSSSI) subtype/diagnosis (major abscess, diabetic foot infection, wound infection or infected ischaemic ulcer), surgical intervention and severity of illness. Diagnoses and disease severity were based on predetermined criteria, documented by repeated photographs, and confirmed by an independent data review committee. Patients were randomized to receive either 400 mg of moxifloxacin iv once daily followed by 400 mg of moxifloxacin orally once daily or 4.0/0.5 g of TZP iv thrice daily followed by 875/125 mg of AMC orally twice daily for 7-21 days. The primary efficacy variable was clinical response at test of cure (TOC) for the per-protocol (PP) population. Clinical efficacy was assessed by the data review committee based on repeated photographs and case descriptions. Clinical trials registry number: NCT 00402727. RESULTS: A total of 813 patients were randomized. Clinical success rates at TOC were similar for moxifloxacin and TZP-AMC in the PP [320/361 (88.6%) versus 275/307 (89.6%), respectively; P = 0.758] and intent-to-treat (ITT) [350/426 (82.2%) versus 305/377 (80.9%), respectively; P = 0.632] populations. Thus, moxifloxacin was non-inferior to TZP-AMC. Bacteriological success rates were high in both treatment arms [moxifloxacin: 432/497 (86.9%) versus TZP-AMC: 370/429 (86.2%), microbiologically valid (MBV) population]. Moxifloxacin was non-inferior to TZP-AMC at TOC in both the MBV and the ITT populations. Both treatments were well tolerated. CONCLUSIONS: Once-daily iv/oral moxifloxacin monotherapy was clinically and bacteriologically non-inferior to iv TZP thrice daily followed by oral AMC twice daily in patients with cSSSIs

Lopinavir–ritonavir in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

SummaryBackground Lopinavir–ritonavir has been proposed as a treatment for COVID-19 on the basis of in vitro activity,preclinical studies, and observational studies. Here, we report the results of a randomised trial to assess whether lopinavir–ritonavir improves outcomes in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, platform trial, a range of possible treatments was compared with usual care in patients admitted to hospital with COVID-19. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients were randomly allocated to either usual standard of care alone or usual standard of care plus lopinavir–ritonavir (400 mg and 100 mg, respectively) by mouth for 10 days or until discharge (or one of the otherRECOVERY treatment groups: hydroxychloroquine, dexamethasone, or azithromycin) using web-based simple (unstratified) randomisation with allocation concealment. Randomisation to usual care was twice that of any of the active treatment groups (eg, 2:1 in favour of usual care if the patient was eligible for only one active group, 2:1:1 if the patient was eligible for two active groups). The primary outcome was 28-day all-cause mortality. Analyses weredone on an intention-to-treat basis in all randomly assigned participants. The trial is registered with ISRCTN,50189673, and ClinicalTrials.gov, NCT04381936.Findings Between March 19, 2020, and June 29, 2020, 1616 patients were randomly allocated to receive lopinavir–ritonavir and 3424 patients to receive usual care. Overall, 374 (23%) patients allocated to lopinavir–ritonavir and 767 (22%) patients allocated to usual care died within 28 days (rate ratio 1·03, 95% CI 0·91–1·17; p=0·60). Resultswere consistent across all prespecified subgroups of patients. We observed no significant difference in time until discharge alive from hospital (median 11 days [IQR 5 to >28] in both groups) or the proportion of patients discharged from hospital alive within 28 days (rate ratio 0·98, 95% CI 0·91–1·05; p=0·53). Among patients not on invasive mechanical ventilation at baseline, there was no significant difference in the proportion who met the composite endpoint of invasive mechanical ventilation or death (risk ratio 1·09, 95% CI 0·99–1·20; p=0·092).Interpretation In patients admitted to hospital with COVID-19, lopinavir–ritonavir was not associated with reductions in 28-day mortality, duration of hospital stay, or risk of progressing to invasive mechanical ventilation or death. These findings do not support the use of lopinavir–ritonavir for treatment of patients admitted to hospital with COVID-19.Funding Medical Research Council and National Institute for Health Research

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN