Results from photooxidation of aromatic compounds in a reaction chamber show that a substantial fraction of the organic aerosol mass is composed of polymers. This polymerization results from ...reactions of carbonyls and their hydrates. After aging for more than 20 hours, about 50% of the particle mass consists of polymers with a molecular mass up to 1000 daltons. This results in a lower volatility of this secondary organic aerosol and a higher aerosol yield than a model using vapor pressures of individual organic species would predict.
Clostridium botulinum produces seven antigenically distinct neurotoxins C. botulinum neurotoxins (BoNTs) A–G sharing a significant sequence homology. Based on sequence and functional similarity, it ...was believed that their three-dimensional structures will also be similar. Indeed, the crystal structures of BoNTs A and B exhibit similar fold and domain association where the translocation domain is flanked on either side by binding and catalytic domains. Here, we report the crystal structure of BoNT E holotoxin and show that the domain association is different and unique, although the individual domains are similar to those of BoNTs A and B. In BoNT E, both the binding domain and the catalytic domain are on the same side of the translocation domain, and all three have mutual interfaces. This unique association may have an effect on the rate of translocation, with the molecule strategically positioned in the vesicle for quick entry into cytosol. Botulism, the disease caused by BoNT E, sets in faster than any other serotype because of its speedy internalization and translocation, and the present structure offers a credible explanation. We propose that the translocation domain in other BoNTs follows a two-step process to attain translocation-competent conformation as in BoNT E. We also suggest that this translocation-competent conformation in BoNT E is a probable reason for its faster toxic rate compared to BoNT A. However, this needs further experimental elucidation.
In the digital economy, consumer vulnerability is not simply a vantage point from which to assess some consumers’ lack of ability to activate their awareness of persuasion. Instead, digital ...vulnerability describes a universal state of defencelessness and susceptibility to (the exploitation of) power imbalances that are the result of the increasing automation of commerce, datafied consumer–seller relations, and the very architecture of digital marketplaces. Digital vulnerability, we argue, is architectural, relational, and data-driven. Based on our concept of digital vulnerability, we demonstrate how and why using digital technology to render consumers vulnerable is the epitome of an unfair digital commercial practice.
The heterogeneous reaction of ozone with oleic acid (OA) aerosol particles was studied as function of humidity and reaction time in an aerosol flow reactor using an off-line gas chromatography mass ...spectrometry (GC–MS) technique. We report quantitative yields of the major C9 ozonolysis products in both gas and condensed phases and the effect of relative humidity on the product distribution. The measurements were carried out with OA aerosol particles at room temperature. The results indicate that the product yields are increasing with increasing relative humidity during the reaction. Nonanal (NN) was detected as the major gas-phase product (55.6 ± 2.3%), with 94.5 ± 2.4% of the NN yield in the gas, and 5.5 ± 2.7% in the particulate phase, whereas nonanoic, oxononanoic and azelaic acids were detected exclusively in the particulate phase. Using UV-spectrometry, we observed that peroxides make up the largest fraction of products, about half of the product aerosol mass, and their concentration decreased with increasing humidity.
The introduction and rapid transmission of SARS-CoV-2 in the United States resulted in methods to assess, mitigate, and contain the resulting COVID-19 disease derived from limited knowledge. ...Screening for testing has been based on symptoms typically observed in inpatients, yet outpatient symptoms may differ. Classification and regression trees recursive partitioning created a decision tree classifying participants into laboratory-confirmed cases and non-cases. Demographic and symptom data from patients ages 18-87 years enrolled from March 29-June 8, 2020 were included. Presence or absence of SARS-CoV-2 was the target variable. Of 832 tested, 77 (9.3%) tested positive. Cases significantly more often reported diarrhea (12 percentage points (PP)), fever (15 PP), nausea/vomiting (9 PP), loss of taste/smell (52 PP), and contact with a COVID-19 case (54 PP), but less frequently reported sore throat (-27 PP). The 4-terminal node optimal tree had sensitivity of 69%, specificity of 78%, positive predictive value of 20%, negative predictive value of 97%, and AUC of 76%. Among those referred for testing, negative responses to two questions could classify about half (49%) of tested persons with low risk for SARS-CoV-2 and would save limited testing resources. Outpatient symptoms of COVID-19 appear to be broader than the inpatient syndrome.Initial supplies of anticipated COVID-19 vaccines may be limited and administration of first such available vaccines may need to be prioritized for essential workers, the most vulnerable, or those likely to have a robust response to vaccine. Another priority group could be those not previously infected. Those who screen out of testing may be less likely to have been infected by SARS-CoV-2 virus thus may be prioritized for vaccination when supplies are limited.
Secondary organic aerosol (SOA) formation from the photooxidation of an anthropogenic (1,3,5-trimethylbenzene) and a biogenic (alpha-pinene) precursor was investigated at the new PSI smog chamber. ...The chemistry of the gas phase was followed by proton transfer reaction mass spectrometry, while the aerosol chemistry was investigated with aerosol mass spectrometry, ion chromatography, laser desorption ionization mass spectrometry, and infrared spectroscopy, along with volatility and hygroscopicity studies. Evidence for oligomer formation for SOA from both precursors was given by an increasing abundance of compounds with a high molecular weight (up to 1000 Da) and by an increasing thermal stability with increasing aging time. The results were compared to data obtained from ambient aerosol samples, revealing a number of similar features.
In vivo corneal light scattering measurements using a novel confocal microscope demonstrated greatly increased backscatter from corneal stromal fibrocytes (keratocytes) in opaque compared to ...transparent corneal tissue in both humans and rabbits. Additionally, two water-soluble proteins, transketolase (TKT) and aldehyde dehydrogenase class 1 (ALDH1), isolated from rabbit keratocytes showed unexpectedly abundant expression ( approximately 30% of the soluble protein) in transparent corneas and markedly reduced levels in opaque scleral fibroblasts or keratocytes from hazy, freeze injured regions of the cornea. Together these data suggest that the relatively high expressions of TKT and ALDH1 contribute to corneal transparency in the rabbit at the cellular level, reminiscent of enzyme-crystallins in the lens. We also note that ALDH1 accumulates in the rabbit corneal epithelial cells, rather than ALDH3 as seen in other mammals, consistent with the taxon-specificity observed among lens enzyme-crystallins. Our results suggest that corneal cells, like lens cells, may preferentially express water-soluble proteins, often enzymes, for controlling their optical properties.
Little is known about the effects of a mild SARS-CoV-2 infection on health-related quality of life.
This prospective observational study of symptomatic adults (18–87 years) who sought outpatient care ...for an acute respiratory illness, was conducted from 3/30/2020 to 4/30/2021. Participants completed the Short Form Health Survey (SF-12) at enrollment and 6–8 weeks later, to report their physical and mental health function levels as measured by the physical health and mental health composite scores (PHC and MHC, respectively). PHC and MHC scores for COVID-19 cases and non-COVID cases were compared using t-tests. Multivariable regression modeling was used to determine predictors of physical and mental health function at follow-up.
Of 2301 enrollees, 426 COVID-19 cases and 547 non-COVID cases completed both surveys. PHC improved significantly from enrollment to follow-up for both COVID-19 cases (5.4 ± 0.41; P < 0.001) and non-COVID cases (3.3 ± 0.32; P < 0.001); whereas MHC improved significantly for COVID-19 cases (1.4 ± 0.51; P < 0.001) and decreased significantly for non-COVID cases (−0.8 ± 0.37; P < 0.05). Adjusting for enrollment PHC, the most important predictors of PHC at follow-up included male sex (β = 1.17; SE = 0.5; P = 0.021), having COVID-19 (β = 1.99; SE = 0.54; P < 0.001); and non-white race (β = −2.01; SE = 0.70; P = 0.004). Adjusting for enrollment MHC, the most important predictors of MHC at follow-up included male sex (β = 1.92; SE = 0.63; P = 0.002) and having COVID-19 (β = 2.42; SE = 0.67; P < 0.001).
Both COVID-19 cases and non-COVID cases reported improved physical health function at 6–8 weeks’ convalescence; whereas mental health function improved among COVID-19 cases but declined among non-COVID cases. Both physical and mental health functioning were significantly better among males with COVID-19 than females.
•Little is known about the effects of a mild SARS-CoV-2 infection on health-related quality of life (QoL).•Health related QoL was measured among outpatients with acute respiratory illness enrollment and 6-8 weeks later.•Physical health function improved during convalescence for both COVID-19 cases and non-COVID cases.•Mental health function improved among COVID-19 cases but declined among non-COVID cases.•Male sex and having COVID-19 were predictors of improved physical and mental health functioning at follow-up.
The atomic structures of two proteins in the histidine biosynthesis pathway consist of β/α barrels with a twofold repeat pattern. It is likely that these proteins evolved by twofold gene duplication ...and gene fusion from a common half-barrel ancestor. These ancestral domains are not visible as independent domains in the extant proteins but can be inferred from a combination of sequence and structural analysis. The detection of subdomain structures may be useful in efforts to search genome sequences for functionally and structurally related proteins.
Organic acids in the gas and aerosol phase from photooxidation of 1,3,5-trimethylbenzene in the presence of 300 ppb propene and 300 ppb NOx in smog chamber experiments were determined using a wet ...effluent diffusion denuder/aerosol collector coupled to ion chromatography (IC) with conductivity detection. Behind the IC, the samples were collected using a fraction collector, for identification of unresolved/unidentified organic acids with IC−mass spectrometry (MS). In total, 20 organic acids were found with MS of which 10 were identified. The organic acids identified offline by IC−MS were then further quantified based on the online IC data. The identification was additionally confirmed with gas chromatography−mass spectrometry. At the maximum aerosol concentration, organic acids comprised 20−45% of the total aerosol mass. The method has a detection limit of 10−100 ng/m3 for the identified carboxylic acids.
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