Ozonolysis can produce long-lived greenhouse gases from commercial refrigerants.

Hydrofluoroolefins are being adopted as sustainable alternatives to long-lived fluorine- and chlorine-containing gases and are finding current or potential mass-market applications as refrigerants, among a myriad of other uses. Their olefinic bond affords relatively rapid reaction with hydroxyl radicals present in the atmosphere, leading to short lifetimes and proportionally small global warming potentials. However, this type of functionality also allows reaction with ozone, and whilst these reactions are slow, we show that the products of these reactions can be extremely long-lived. Our chamber measurements show that several industrially important hydrofluoroolefins produce CHF3 (fluoroform, HFC-23), a potent, long-lived greenhouse gas. When this process is accounted for in atmospheric chemical and transport modeling simulations, we find that the total radiative effect of certain compounds can be several times that of the direct radiative effect currently recommended by the World Meteorological Organization. Our supporting quantum chemical calculations indicate that a large range of exothermicity is exhibited in the initial stages of ozonolysis, which has a powerful influence on the CHF3 yield. Furthermore, we identify certain molecular configurations that preclude the formation of long-lived greenhouse gases. This demonstrates the importance of product quantification and ozonolysis kinetics in determining the overall environmental impact of hydrofluoroolefin emissions.

Airborne observations over the North Atlantic Ocean reveal the importance of gas-phase urea in the atmosphere.

Reduced nitrogen (N) is central to global biogeochemistry, yet there are large uncertainties surrounding its sources and rate of cycling. Here, we present observations of gas-phase urea (CO(NH2)2) in the atmosphere from airborne high-resolution mass spectrometer measurements over the North Atlantic Ocean. We show that urea is ubiquitous in the lower troposphere in the summer, autumn, and winter but was not detected in the spring. The observations suggest that the ocean is the primary emission source, but further studies are required to understand the responsible mechanisms. Urea is also observed aloft due to long-range transport of biomass-burning plumes. These observations alongside global model simulations point to urea being an important, and currently unaccounted for, component of reduced-N to the remote marine atmosphere. Airborne transfer of urea between nutrient-rich and -poor parts of the ocean can occur readily and could impact ecosystems and oceanic uptake of carbon dioxide, with potentially important climate implications.

Evidence of gene-nutrient interaction association with waist circumference, cross-sectional analysis.

BACKGROUND AND AIMS: Waist circumference (WC) is a significant indicator of body adiposity and is associated with increased mortality and morbidity of cardiovascular diseases. Although, single nutrient intake and candidate genes were previously associated with WC. Little is known about WC association with overall diet quality, genetic risk score and gene-nutrient interaction. This study aims to investigate the influence of overall diet quality and multiple WC-associated single nucleotide polymorphisms on WC. In addition to investigating gene-nutrient interaction association with WC. METHODS: This study explored cross-sectional data from two large sample-size studies, to provide reproducible results. As a representation of the UK population, the Airwave Health Monitoring Study (n = 6,502) and the UK-Biobank Cohort Study (n = 171,129) were explored for factors associated with WC. Diet quality was evaluated based on the Mellen Index for Dietary Approaches to Stop Hypertension (Mellen-DASH). The genetic risk score for WC (GRS-Waist) was calculated by screening the population genotype for WC-associated single nucleotide polymorphisms. Multivariate linear regression models were built to explore WC association with diet quality and genetic risk score. Gene-nutrient interaction was explored by introducing the interaction term (GRS-Waist X Mellen-DASH score) to multivariate linear regression analysis. RESULTS: The prevalence of high WC (Female > 80 cm, Male > 94 cm) was 46.5% and 51.7% in both populations. Diet quality and genetic risk score of WC were significantly associated with WC. There was no evidence of interaction between GRS-Waist, DASH diet scores and nutrient intake on WC. CONCLUSION: This study's findings provided reproducible results on waist circumference association with diet and genetics and tested the possibility of gene-nutrient interaction. These reproducible results are successful in building the foundation for using diet and genetics for early identification of those at risk of having high WC and WC-associated diseases. In addition, evidence on gene-diet interactions on WC is limited and lacks replication, therefore our findings may guide future research in investigating this interaction and investigating its application in precision nutrition.

Deliveries in Lebanon, the Country with the Highest Refugee Density in the World: A Descriptive Review.

PURPOSE: The aim of this study is to analyze obstetrical and reproductive health parameters in Lebanon from 2015 until 2018 in the setting of the Syrian refugee influx in order to evaluate potential risks and provide a management plan to improve outcomes. DESCRIPTION: Data from the Lebanese Ministry of Public Health (LMPH) on all obstetrical deliveries that occurred in Lebanon between 2015 and 2018 was screened and analyzed. Number and mode of delivery as well as maternal and neonatal outcomes were included. Joinpoint regression analysis was used for trends of selected parameters. Independent two-sample t-tests were used for comparisons. ASSESSMENT: Women of non-Lebanese nationality residing in Lebanon had a significantly greater number of total deliveries (p-value < 0.001), vaginal deliveries (p-value = 0.002), cesarean sections (p-value = 0.02). When looking at delivery trends from 2015 to 2018, Lebanese women had a significant decrease in total number of deliveries (p-value < 0.001) and vaginal deliveries (p-value < 0.001). CONCLUSION: Total number of deliveries and cesarean sections is on the rise in Lebanon. Cesarean section practice should be audited by the LMPH and the Lebanese Order of Physicians (LOP). Local and international agencies should prioritize the implementation and management of family planning facilities in refugee hosting countries.

Sex and obesity status modify the association between vitamin D and eczema among adolescents.

BACKGROUND: Epidemiologic studies have reported inconsistent associations between vitamin D and eczema. This study sought to assess whether sex and obesity status could modify the association between vitamin D and eczema. METHODS: A cross-sectional study enrolled 763 adolescents in Kuwait. 25-hydroxyvitamin D (25(OH)D) was measured in venous blood. Current eczema was defined according to clinical history and characteristic morphology and distribution. RESULTS: In sex-stratified analysis, decreased 25(OH)D levels were associated with increased current eczema prevalence among males (adjusted odds ratio (aOR)tertile 1 vs. tertile 3: 2.14, 95% confidence intervals (CI): 1.07-4.56), but not among females (aORtertile 1 vs. tertile 3: 1.08, 95% CI: 0.71-1.66). Further stratification by obesity status showed that lower 25(OH)D levels were associated with increased current eczema prevalence among overweight/obese males (per 10-unit decrease in 25(OH)D levels: aOR: 1.70, 95% CI: 1.17-2.46). Such an association was weaker and statistically non-significant among overweight/obese females (per 10-unit decrease in 25(OH)D levels: aOR: 1.26, 95% CI: 0.93-1.70). CONCLUSIONS: Sex and obesity status modified the association between vitamin D levels and eczema, with an inverse association observed among overweight/obese males, but not among overweight/obese females. These results suggest that preventive and clinical management strategies could vary by sex and obesity status. IMPACT: The current study showed that sex and obesity modify the association between vitamin D and eczema among adolescents. An inverse association between vitamin D and eczema was observed among overweight/obese males, but this association was not as pronounced among overweight/obese females. Vitamin D was not associated with eczema among underweight/normal weight males and females. The identification of effect modification by sex and obesity status add to the current scientific knowledge and further highlight the complexity of the association between vitamin D and eczema. These results may promote a more individualized approach to the future prevention and clinical management of eczema.

Direct kinetic measurements and theoretical predictions of an isoprene-derived Criegee intermediate.

Isoprene has the highest emission into Earth's atmosphere of any nonmethane hydrocarbon. Atmospheric processing of alkenes, including isoprene, via ozonolysis leads to the formation of zwitterionic reactive intermediates, known as Criegee intermediates (CIs). Direct studies have revealed that reactions involving simple CIs can significantly impact the tropospheric oxidizing capacity, enhance particulate formation, and degrade local air quality. Methyl vinyl ketone oxide (MVK-oxide) is a four-carbon, asymmetric, resonance-stabilized CI, produced with 21 to 23% yield from isoprene ozonolysis, yet its reactivity has not been directly studied. We present direct kinetic measurements of MVK-oxide reactions with key atmospheric species using absorption spectroscopy. Direct UV-Vis absorption spectra from two independent flow cell experiments overlap with the molecular beam UV-Vis-depletion spectra reported recently [M. F. Vansco, B. Marchetti, M. I. Lester, J. Chem. Phys. 149, 44309 (2018)] but suggest different conformer distributions under jet-cooled and thermal conditions. Comparison of the experimental lifetime herein with theory indicates only the syn-conformers are observed; anti-conformers are calculated to be removed much more rapidly via unimolecular decay. We observe experimentally and predict theoretically fast reaction of syn-MVK-oxide with SO2 and formic acid, similar to smaller alkyl-substituted CIs, and by contrast, slow removal in the presence of water. We determine products through complementary multiplexed photoionization mass spectrometry, observing SO3 and identifying organic hydroperoxide formation from reaction with SO2 and formic acid, respectively. The tropospheric implications of these reactions are evaluated using a global chemistry and transport model.

Effect of Sustained Uterine Compression versus Uterine Massage on Blood Loss after Vaginal Delivery: A Randomized Controlled Trial.

OBJECTIVE: This study aimed to compare the effectiveness of sustained uterine compression versus uterine massage in reducing blood loos after a vaginal delivery. STUDY DESIGN: This was a prospective randomized trial conducted at the American University of Beirut Medical Center (AUBMC) between October 2015 and October 2017. Inclusion criteria were women with a singleton pregnancy at ≥36 weeks of gestation, with less than three previous deliveries, who were candidates for vaginal delivery. Participants were randomized into two groups, a sustained uterine compression group (group 1) and a uterine massage group (group 2). Incidence of postpartum hemorrhage (blood loss of ≥500 mL) was the primary outcome. We assumed that the incidence of postpartum hemorrhage at our institution is similar to previously published studies. A total of 545 women were required in each arm to detect a reduction from 9.6 to 4.8% in the primary outcome (50% reduction) with a one-sided α of 0.05 and a power of 80%. Factoring in a 10% dropout rate. Secondary outcomes were admission to intensive care unit (ICU), postpartum complications, drop in hemoglobin, duration of hospital stay, maternal pain, use of uterotonics, or of surgical procedure for postpartum hemorrhage. RESULTS: A total of 550 pregnant women were recruited, 273 in group 1 and 277 in group 2. There was no statistically significant difference in baseline characteristics between the two groups. Type of anesthesia, rate of episiotomy, lacerations, and mean birth weight were also equal between the groups. Incidence of the primary outcome was not different between the two groups (group 1: 15.5%, group 2: 15.4%; p = 0.98). There was no statistically significant difference in any of the secondary outcomes between the two groups, including drop in hemoglobin (p = 0.79). CONCLUSION: There was no difference in blood loss between sustained uterine compression and uterine massage after vaginal delivery. KEY POINTS: · Transabdominal uterine compression and uterine massage are appropriate to prevent postpartum hemorrhage.. · No significant difference in blood loss or maternal discomfort observed between the two techniques.. · Both methods are equally effective and either one can be used based on provider preference..

First Report of Colletotrichum gloeosporioides and Colletotrichum siamense, Causing Anthracnose Disease on coffee trees, in Saudi Arabia.

Coffee (Coffea arabica L.) is a promising agricultural commodity in many countries including Saudi Arabia, but crop production is often constrained by diseases. In December 2021, coffee trees had symptoms of anthracnose disease (CAD) were observed in Jazan Province, Saudi Arabia (17°19'00.8"N 43°11'26.8"E), and the incidence was 55%. Affected trees showed dieback and leaves necrosis. On green and ripening berries, slightly sunken and dark brown lesions were occurred; the berries finally become mummified (Fig. S1). For pathogen isolation, symptomatic tissues (4×4mm) of 30 diseased branches and berries samples were surface-sterilized in 1% sodium hypochlorite for 2 min, followed by 70% ethanol for 20 s, rinsed in sterile distilled water and placed on potato dextrose agar (PDA). Cultures were incubated at 26℃ for 8 days in the dark. Eighteen isolates were recovered, and 2 representative single spore isolates (KSU-CgM17, KSU-CsM42) were used for further study. PDA culture of KSU-CgM17 had aerial white mycelium at first and later became gray to grayish black; light salmon to orange conidial masses were observed on the mycelium plate surface as the cultures aged (Fig. S2). Colony produced by KSU-CsM42 was off-white to gray with cottony mycelia and grayish-white on the undersides of the culture after 10 days at 28° (Fig. S2). Conidial shape of these two isolates were both aseptate, cylindrical to nearly straight, hyaline, rounded at both ends. Conidia (n = 50) measurements were 16 to 18.0 µm long × 4.8 to 6.4 µm wide for KSU-CgM17 and 12.6 to 17.5 µm long × 3.2 to 4.5 µm wide for KSU-CsM42. The microscopic and culture features fitted those for Colletotrichum gloeosporioides species complex (Weir et al. 2012). To further identify these isolates, four genomic DNA loci including the partial ITS rDNA region, and CAL, TUB2, and GAPDH genes were amplified and sequenced (Hu et al., 2015). All sequences were deposited into GenBank under accession numbers: OQ791412 & OQ791413 (ITS), OQ786847 & OQ786851 (CAL), OQ786849 & OQ786850 (TUB2), and OQ786848 & OQ786852 (GAPDH) for KSU-CgM17and KSU-CsM42, respectively (Tables S1& S2). A BLAST search of GenBank showed that these pathogens were identified as C. gloeosporioides (KSU-CgM17) and C. siamense (KSU-CsM42). The pathogenicity was tested on detached coffee leaves or green and red berries (Coa et al., 2019). For inoculation, healthy leaves and berries were wounded with a sterilized needle, placed inside petri dishes containing moist filter paper, and then inoculated with a 10-µl droplet of conidial suspension (106 spores/ ml). Sterile distilled water was used as a negative control. Six replicates were tested per isolate and the experiment was repeated once. The inoculated materials were incubated at 25°C and 100% relative humidity for 8 days. Necrotic lesions developed on 100% of the inoculated coffee materials 6 days later, whereas the negative controls were asymptomatic (Fig. S2). Koch's postulates were fulfilled when typical colonies of these species were successfully re-isolated from the from symptomatic tissues. These pathogens were reported previously to affect coffee in Vietnam (Nguyen et al., 2010), China (Cao et al., 2019), and Puerto Rico (Serrato-Diaz et al., 2020). To our knowledge, this is the first record of C. gloeosporioides and C. siamense causing CAD in Saudi Arabia. Further studies on the epidemiology of CAD on arabica coffee plantations as well as effective strategies for managing this disease are needed.

First Report of Basal Rot of Onion Caused by Fusarium oxysporum f. sp. cepae in Saudi Arabia.

Onion (Allium cepa L.) is a globally important crop worldwide including Saudi Arabia. In November 2020, 2-month-old onion plants (cv. Redwing) in commercial fields within the Sajir area of Riyadh region (∼ 1.4 ha), showed symptoms of yellowing, wilting, stunting, bulb discoloration, rot in the basal parts of bulb and decrease in roots. In the advanced stages, the affected plants collapsed and died. The incidence of symptomatic plants ranged from 30 to 65% in the surveyed fields. To isolate the pathogen, symptomatic onion plants (n =20) were sampled. Diseased tissues from roots and bulbs were cut into small pieces (4 × 4 mm), sanitized with 1% sodium hypochlorite solution for 2 min, submerged in 70% alcohol for 20 s, then rinsed with sterile water, before plating on potato dextrose agar (PDA) medium. The plates were incubated at 25°C for 6 days. Subcultures of the mycelia grown out of the diseased tissues produced purplish pink fungal colonies on PDA. On carnation leaf agar, cultures were characteristic of Fusarium oxysporum as described by Leslie and Summerell (2006), with the presence of unicellular microconidia (3.8 to 7.8 × 1.7 to 2.5 µm, n= 50) without septa in false heads or short monophialides and slightly curved macroconidia (16.3 to 28 × 4.2 to 6.1 µm, n= 50) with two to four septa. Older mycelia developed many chlamydospores that were single or in short chains. To further confirm the pathogen identification, DNA was extracted from single-spore cultures of three representative isolates using the DNeasy Plant Mini kit (QIAGEN, Hilden, Germany). Three different fungal nuclear regions of internal transcribed spacer (ITS), elongation factor 1-α, (TEF1-α) and the second largest subunit of DNA-directed RNA polymerase II (RPB2) DNA were amplified by PCR and sequenced with the following primers: ITS4 and ITS5 (White et al. 1990); EF-1 and EF-2 (O'Donnell et al. 2008); and fRPB2-5F and fRPB2-7cR (Liu et al. 1999), respectively. Phylogenetic analysis based on the alignment of the ITS, TEF1-α, and RPB2 sequences using MEGA7 placed these isolates in the F. oxysporum clade. The ITS, TEF1-α, and RPB2 sequences of an isolate FOC-OR9 were submitted to GenBank (OL721757, OL764494, and OL764495 respectively). To confirm the forma specialis cepae, a fragment of the F. oxysporum f. sp. cepae gene Secreted In Xylem 3 (SIX3) was amplified by PCR (Kalman et al. 2020). The SIX3 amplicon (∼ 277-bp) was sent for sequencing, and the sequence was submitted to GenBank (OL828265). BLASTn analysis of the sequences showed 100% identity with F. oxysporum f. sp. cepae (KP746408). To fulfill Koch's postulates, pathogenicity tests were performed with healthy onion bulbs cv. "Redwing" of 100-150 g each. Prior to inoculation of onion bulbs, the dry bulb scales, one of the fleshy inner scales, as well as the roots were removed. Bulbs were then surface sterilized (as described above) and injected with 20 µl of a conidial suspension (106 spores/ ml) into the basal plate of each bulb and approximately 1 cm deep into the tissue. Six bulbs were inoculated for each isolate, placed in a mesh bag, and incubated at 28 °C in the dark. Six bulbs injected with sterile water and six non-inoculated bulbs served as controls. At the 4th week post inoculation, necrotic rot symptoms and brown discoloration were observed on the basal plates of these inoculated bulbs (similar symptoms to those observed in the field), while control treatments showed no symptoms. The pathogen was re-isolated from the basal plates onto PDA and identified morphologically and molecularly as F. oxysporum f. sp. cepae, thus fulfilling Koch's postulates. The test was repeated twice. This pathogen was previously reported causing onion basal rot in United Kingdom (Taylor, et al., 2013). To our knowledge, this is the first report of basal rot in onion caused by F. oxysporum f. sp. cepae in Saudi Arabia. It is recommended that preventive management should be considered as this disease may cause significant economic losses for onion growers in Saudi Arabia. Also, Fusarium mycotoxin contamination of onion bulb could pose a public health risk.

Flipping the Thinking on Equality, Diversity, and Inclusion. Why EDI Is Essential for the Development and Progression of the Chemical Sciences: A Case Study Approach.

All learners have a contribution to make to the development of the Chemical Sciences, be that in novel ways to teach, and their perspectives and contexts, but also in research, both in chemical education and the wider Chemical Sciences. Through four case studies, this paper explores interactions with diverse groups and how this has altered perspectives on both teaching and research. The case studies include work with visually impaired adults, a project bringing together First Peoples in Australia with academics to explore old ways (traditional science) and new ways (modern approaches), primary (elementary) school perspectives on teaching science, and a project in South Africa to connect university and township communities. Not only do these case studies demonstrate the immense value these diverse groups bring to our understanding about how to learn, but they also bring new perspectives on how to view and solve chemical problems.

The 30-day hospital readmission and mortality after surgery in colorectal cancer patients.

PURPOSE: Hospital readmissions in the first weeks following surgery are common, expensive, and associated with increased mortality among colorectal cancer patients. This study is designed to assess the 30-day hospital readmission after colorectal cancer surgery and evaluate the risk factors that affect hospital readmission. METHODS: The study uses data from the Ministry of National Guard-Health Affairs Cancer Registry. All colorectal cancer patients who underwent colorectal cancer surgery between January 1, 2016, and November 31, 2021, were investigated. Factors examined were age, gender, marital status, Body Mass Index, Charlson Comorbidity Index, chemotherapy, radiotherapy, tumor stage, grade, site, surgical approach, length of stay, and discharge location. Kaplan-Meier curves were constructed to assess survival rates between readmitted and non-readmitted patients, and logistic regressions were performed to assess predictors of readmission. RESULTS: A total of 356 patients underwent tumor resection and 49 patients were readmitted within 30-day of index discharge. The most common reasons for hospital readmissions were gastrointestinal (22.45%), urinary tract infection (16.33%), and surgical site infection (12.24%). In the multivariable analysis, females were 89% more likely to be readmitted compared to males (odds ratio 1.89, 95% confidence intervals 1.00-3.58). Patients with distant metastatic tumors have higher odds of readmission (odds ratio 4.52, 95% confidence intervals 1.39-14.71) compared to patients with localized disease. CONCLUSIONS: Colorectal cancer readmission is more common in patients with metastatic disease. Strategies to reduce readmission include planned transition to outpatient care, especially among patients with a high risk of readmission.

The impact of pain on quality of life in patients with osteoarthritis: a cross-sectional study from Palestine.

BACKGROUND: Osteoarthritis is one of the most common musculoskeletal problems. Pain is the most common complaint and the most significant cause of decreased health-related quality of life (HRQOL) among osteoarthritic patients. The objectives of this study were to assess the impact of pain on quality of life among patients with osteoarthritis and to assess the association of sociodemographic and clinical factors with HRQOL. METHODS: Using a cross-sectional study design, we collected data from osteoarthritis patients in orthopedic outpatient clinics from four hospitals in the Palestine-West bank between November 2020 and March 2021. We used the Brief Pain Inventory (BPI) scale to assess pain and the Quality of Life scale five dimensions (EQ-5D) with the visual analog scale of the European Quality of Life (EQ-VAS) to assess HRQOL. RESULTS: In our study, 196 patients composed the final sample, with an average of 60.12 ± 13.63 years. The medians for the EQ-5D score and EQ-VAS score were 0.72 (0.508-0.796) and 70 (55-85), respectively. The pain severity score was found to have a significant negative association with both the EQ-5D and EQ-VAS scores with r of - 0.620, p <  0.001, and - 0.554, p <  0.001, respectively. Similar associations were found between pain interference score and both EQ-5D (r = - 0.822, p <  0.001) and EQ-VAS scores (r = - 0.609, p <  0.001). Multiple regression analysis showed that participants with higher educational level (p = 0.028), less diseased joints (p = 0.01), shorter duration of disease (p = 0.04), and lesser pain severity and interference scores (both with p < 0.001) had significantly higher HRQOL scores. CONCLUSIONS: We found that many variables have a significant negative impact on HRQOL among patients with osteoarthritis. Our finding provides a well-founded database to use by clinicians and healthcare professionals who work with patients with osteoarthritis, as well as educational and academic institutions.

Investigating the background and local contribution of the oxidants in London and Bangkok.

The contribution of NOx emissions and background O3 to the sources and partitioning of the oxidants [OX (= O3 + NO2)] at the Marylebone Road site in London during the 2000s and 2010s has been investigated to see the impact of the control measures or technology changes inline with the London Mayor's Air Quality Strategy. The abatement of the pollution emissions has an impact on the trends of local and background oxidants, [OX]L and [OX]B, decreasing by 1.4% per year and 0.4% per year, respectively from 2000 to 2019. We also extend our study to three roadside sites (Din Daeng, Thonburi and Chokchai) in another megacity, Bangkok, to compare [OX]L and [OX]B and their behavioural changes with respect to the Marylebone Road site. [OX]L and [OX]B at the Marylebone Road site (0.21[NOx] and 32 ppbv) are comparable with the roadside sites of Thailand (0.12[NOx] to 0.26[NOx] and 29 to 32 ppbv). The seasonal variation of [OX]B levels displays a spring maximum for London, which is due to the higher northern hemispheric ozone baseline, but a maximum during the dry season is found for Bangkok which is likely due to regional-scale long-range transport from the Asian continent. The diurnal variations of [OX]L for both London and Bangkok roadside sites confirm the dominance of the oxidants from road transport emissions, which are found to be higher throughout the daytime. WRF-Chem-CRI model simulations of the distribution of [OX] showed that the model performed well for London background sites when predicting [OX] levels compared with the measured [OX] levels suggesting that the model is treating the chemistry of the oxidants correctly. However, there are large discrepancies for the model-measurement [OX] levels at the traffic site because of the difficulties in the modelling of [OX] at large road networks in megacities for the complex sub grid-scale dynamics that are taking place, both in terms of atmospheric processes and time-varying sources, such as traffic volumes. For roadside sites in Bangkok, the trend in changes of [OX] is predicted by the model correctly but overestimated in absolute magnitude. We suggest that this large deviation is likely to be due to discrepancies in the EDGAR emission inventory (emission overestimates) beyond the resolution of the model.

Vitamin D levels in relation to low back pain during adolescence.

This study aimed to investigate the association between 25-hydroxyvitamin D (25(OH)D) level and low back pain (LBP) among adolescents while adjusting for potential confounders pertinent to this age group including the weight of school bags, BMI and physical activity. A cross-sectional study was conducted on 760 randomly selected adolescents in middle schools. Data on LBP and the risk factors for LBP were collected from parents by a self-administered questionnaire and from adolescents by face-to-face interview. Blood samples were tested in an accredited laboratory; and 25(OH)D was measured using liquid chromatography-tandem MS. The lifetime prevalence and the 6-month prevalence of LBP were 32·28 (95 % CI 28·97, 35·73) % and 21·26 (95 % CI 18·40, 24·33) %, respectively. There was no difference in the geometric mean of 25(OH)D between those with and without LBP in the past 6 months (28·50 nmol/l and 30·82 nmol/l, respectively; P = 0·122). There was no association between 25(OH)D and LBP in the univariable or multivariable analysis whether 25(OH)D fitted as a continuous or as a categorical variable. We found no association between vitamin D level and LBP in adolescents in an area with high prevalence of vitamin D deficiency. Although it is important to have sufficient vitamin D levels during adolescence for several other health benefits, we concluded that vitamin D is not a major determinant for LBP among adolescents in our setting.

Emissions and Marine Boundary Layer Concentrations of Unregulated Chlorocarbons Measured at Cape Point, South Africa.

Unregulated chlorocarbons, here defined as dichloromethane (CH2Cl2), perchloroethene (C2Cl4), chloroform (CHCl3), and methyl chloride (CH3Cl), are gases not regulated by the Montreal Protocol. While CH3Cl is the largest contributor of atmospheric chlorine, recent studies have shown that growth in emissions of the less abundant chlorocarbons could pose a significant threat to the recovery of the ozone layer. Despite this, there remain many regions for which no atmospheric monitoring exists, leaving gaps in our understanding of global emissions. Here, we report on a new time series of chlorocarbon measurements from Cape Point, South Africa for 2017, which represent the first published high-frequency measurements of these gases from Africa. For CH2Cl2 and C2Cl4, the majority of mole fraction enhancements were observed from the north, consistent with anthropogenically modified air from Cape Town, while for CHCl3 and CH3Cl, we found evidence for both oceanic and terrestrial sources. Using an inverse method, we estimated emissions for south-western South Africa (SWSA). For each chlorocarbon, SWSA accounted for less than 1% of global emissions. For CH2Cl2 and C2Cl4, we extrapolated using population statistics and found South African emissions of 8.9 (7.4-10.4) Gg yr-1 and 0.80 (0.64-1.04) Gg yr-1, respectively.

BACs-on-Beads™ assay, a rapid aneuploidy test, improves the diagnostic yield of conventional karyotyping.

BACs-on-Beads (BoBs™) assay is a rapid aneuploidy test (RAT) that detects numerical chromosomal aneuploidies and multiple microdeletion/microduplication syndromes. This study was conducted to appraise the usefulness of the BoB™ assay as a complementary diagnostic tool to conventional karyotyping for the rapid detection of chromosomal aneuploidies. A total of 485 prenatal (amniotic fluid and chorionic villi) and blood/products of conception samples were collected between July 2013 and August 2018, and analyzed by the BoBs™ assay and cytogenetic karyotyping and further validated by fluorescence in situ hybridization (FISH). Forty-three of 484 qualifying samples (8.9%) were identified as abnormal by the BoBs™ assay. The assay was comparable to karyotyping in the detection of common structural abnormalities (trisomy 21, trisomy 18, X, and Y), with a sensitivity of 96.0% and a specificity of 100%. BoBs™ assay detected 20 microdeletion and microduplication syndromes that were missed by karyotyping. BoBs™, however, missed 10 cases of polyploidies and chromosomal rearrangements which were identified by conventional karyotyping. Our findings suggest that BoBs™ is a reliable RAT which is suitable in combination with conventional karyotyping for the detection of common aneuploidies. The assay also improves the diagnostic yield by recognizing clinically relevant submicroscopic copy number gains and losses.

Experimental Evidence of Dioxole Unimolecular Decay Pathway for Isoprene-Derived Criegee Intermediates.

Ozonolysis of isoprene, one of the most abundant volatile organic compounds emitted into the Earth's atmosphere, generates two four-carbon unsaturated Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). The extended conjugation between the vinyl substituent and carbonyl oxide groups of these Criegee intermediates facilitates rapid electrocyclic ring closures that form five-membered cyclic peroxides, known as dioxoles. This study reports the first experimental evidence of this novel decay pathway, which is predicted to be the dominant atmospheric sink for specific conformational forms of MVK-oxide (anti) and MACR-oxide (syn) with the vinyl substituent adjacent to the terminal O atom. The resulting dioxoles are predicted to undergo rapid unimolecular decay to oxygenated hydrocarbon radical products, including acetyl, vinoxy, formyl, and 2-methylvinoxy radicals. In the presence of O2, these radicals rapidly react to form peroxy radicals (ROO), which quickly decay via carbon-centered radical intermediates (QOOH) to stable carbonyl products that were identified in this work. The carbonyl products were detected under thermal conditions (298 K, 10 Torr He) using multiplexed photoionization mass spectrometry (MPIMS). The main products (and associated relative abundances) originating from unimolecular decay of anti-MVK-oxide and subsequent reaction with O2 are formaldehyde (88 ± 5%), ketene (9 ± 1%), and glyoxal (3 ± 1%). Those identified from the unimolecular decay of syn-MACR-oxide and subsequent reaction with O2 are acetaldehyde (37 ± 7%), vinyl alcohol (9 ± 1%), methylketene (2 ± 1%), and acrolein (52 ± 5%). In addition to the stable carbonyl products, the secondary peroxy chemistry also generates OH or HO2 radical coproducts.

Reaction of Perfluorooctanoic Acid with Criegee Intermediates and Implications for the Atmospheric Fate of Perfluorocarboxylic Acids.

The reaction of perfluorooctanoic acid with the smallest carbonyl oxide Criegee intermediate, CH2OO, has been measured and is very rapid, with a rate coefficient of (4.9 ± 0.8) × 10-10 cm3 s-1, similar to that for reactions of Criegee intermediates with other organic acids. Evidence is shown for the formation of hydroperoxymethyl perfluorooctanoate as a product. With such a large rate coefficient, reaction with Criegee intermediates can be a substantial contributor to atmospheric removal of perfluorocarboxylic acids. However, the atmospheric fates of the ester product largely regenerate the initial acid reactant. Wet deposition regenerates the perfluorocarboxylic acid via condensed-phase hydrolysis. Gas-phase reaction with OH is expected principally to result in formation of the acid anhydride, which also hydrolyzes to regenerate the acid, although a minor channel could lead to destruction of the perfluorinated backbone.

Atmospheric HCFC-22, HFC-125, and HFC-152a at Cape Point, South Africa.

One hydrochlorofluorocarbon and two hydrofluorocarbons (HCFC-22, HFC-125, and HFC-152a) were measured in air samples at the Cape Point observatory (CPT), South Africa, during 2017. These data represent the first such atmospheric measurements of these compounds from southwestern South Africa (SWSA). Baseline atmospheric growth rates were estimated to be 8.36, 4.10, and 0.71 ppt year-1 for HCFC-22, HFC-125, and HFC-152a, respectively. The CPT measurements were combined with an inverse model to investigate emissions from SWSA. For all three halocarbons, Cape Town was found to be the dominant source within SWSA. These estimates were extrapolated, based on population statistics, to estimate emissions for the whole of South Africa. We estimate South Africa's 2017 emissions to be 3.0 (1.6-4.4), 0.8 (0.5-1.2), and 1.1 (0.6-1.6) Gg year-1 for HCFC-22, HFC-125, and HFC-152a, respectively. For all three halocarbons, South Africa's contribution to global emissions is small (<2.5%), but future monitoring is needed to ensure South Africa's compliance with regulation set out by the Montreal Protocol and its Amendments.

Experimental and computational studies of Criegee intermediate reactions with NH3 and CH3NH2.

Ammonia and amines are emitted into the troposphere by various natural and anthropogenic sources, where they have a significant role in aerosol formation. Here, we explore the significance of their removal by reaction with Criegee intermediates, which are produced in the troposphere by ozonolysis of alkenes. Rate coefficients for the reactions of two representative Criegee intermediates, formaldehyde oxide (CH2OO) and acetone oxide ((CH3)2COO) with NH3 and CH3NH2 were measured using cavity ring-down spectroscopy. Temperature-dependent rate coefficients, k(CH2OO + NH3) = (3.1 ± 0.5) × 10-20T2 exp(1011 ± 48/T) cm3 s-1 and k(CH2OO + CH3NH2) = (5 ± 2) × 10-19T2 exp(1384 ± 96/T) cm3 s-1 were obtained in the 240 to 320 K range. Both the reactions of CH2OO were found to be independent of pressure in the 10 to 100 Torr (N2) range, and average rate coefficients k(CH2OO + NH3) = (8.4 ± 1.2) × 10-14 cm3 s-1 and k(CH2OO + CH3NH2) = (5.6 ± 0.4) × 10-12 cm3 s-1 were deduced at 293 K. An upper limit of ≤2.7 × 10-15 cm3 s-1 was estimated for the rate coefficient of the (CH3)2COO + NH3 reaction. Complementary measurements were performed with mass spectrometry using synchrotron radiation photoionization giving k(CH2OO + CH3NH2) = (4.3 ± 0.5) × 10-12 cm3 s-1 at 298 K and 4 Torr (He). Photoionization mass spectra indicated production of NH2CH2OOH and CH3N(H)CH2OOH functionalized organic hydroperoxide adducts from CH2OO + NH3 and CH2OO + CH3NH2 reactions, respectively. Ab initio calculations performed at the CCSD(T)(F12*)/cc-pVQZ-F12//CCSD(T)(F12*)/cc-pVDZ-F12 level of theory predicted pre-reactive complex formation, consistent with previous studies. Master equation simulations of the experimental data using the ab initio computed structures identified submerged barrier heights of -2.1 ± 0.1 kJ mol-1 and -22.4 ± 0.2 kJ mol-1 for the CH2OO + NH3 and CH2OO + CH3NH2 reactions, respectively. The reactions of NH3 and CH3NH2 with CH2OO are not expected to compete with its removal by reaction with (H2O)2 in the troposphere. Similarly, losses of NH3 and CH3NH2 by reaction with Criegee intermediates will be insignificant compared with reactions with OH radicals.