The Identity and Chemistry of C7H7 Radicals Observed during Soot Formation.

We used aerosol mass spectrometry coupled with tunable synchrotron photoionization to measure radical and closed-shell species associated with particle formation in premixed flames and during pyrolysis of butane, ethylene, and methane. We analyzed photoionization (PI) spectra for the C7H7 radical to identify the isomers present during particle formation. For the combustion and pyrolysis of all three fuels, the PI spectra can be fit reasonably well with contributions from four radical isomers: benzyl, tropyl, vinylcyclopentadienyl, and o-tolyl. Although there are significant experimental uncertainties in the isomeric speciation of C7H7, the results clearly demonstrate that the isomeric composition of C7H7 strongly depends on the combustion or pyrolysis conditions and the fuel or precursors. Fits to the PI spectra using reference curves for these isomers suggest that all of these isomers may contribute to m/z 91 in butane and methane flames, but only benzyl and vinylcyclopentadienyl contribute to the C7H7 isomer signal in the ethylene flame. Only tropyl and benzyl appear to play a role during pyrolytic particle formation from ethylene, and only tropyl, vinylcyclopentadienyl, and o-tolyl appear to participate during particle formation from butane pyrolysis. There also seems to be a contribution from an isomer with an ionization energy below 7.5 eV for the flames but not for the pyrolysis conditions. Kinetic models with updated and new reactions and rate coefficients for the C7H7 reaction network predict benzyl, tropyl, vinylcyclopentadienyl, and o-tolyl to be the primary C7H7 isomers and predict negligible contributions from other C7H7 isomers. These updated models provide better agreement with the measurements than the original versions of the models but, nonetheless, underpredict the relative concentrations of tropyl, vinylcyclopentadienyl, and o-tolyl in both flames and pyrolysis and overpredict benzyl in pyrolysis. Our results suggest that there are additional important formation pathways for the vinylcyclopentadienyl, tropyl, and o-tolyl radicals and/or loss pathways for the benzyl radical that are currently unaccounted for in the present models.

Distinguishing Gas-Phase and Nanoparticle Contributions to Small-Angle X-ray Scattering in Reacting Aerosol Flows.

We have developed a strategy for distinguishing between small-angle X-ray scattering (SAXS) from gas-phase species and newly formed nanoparticles in mixed gas- and particle-phase reacting flows. This methodology explicitly accounts for temperature-dependent scattering from gases. We measured SAXS in situ in a sooting linear laminar partially premixed co-flow ethylene/air diffusion flame. The scattering signal demonstrates a downward curvature as a function of the momentum transfer (q) at q values of 0.2-0.57 Å-1. The q-dependent curvature is consistent with the Debye equation and the independent-atom model for gas-phase scattering. This behavior can also be modeled using the Guinier approximation and could be characterized as a Guinier knee for gas-phase scattering. The Guinier functional form can be fit to the scattering signal in this q range without a priori knowledge of the gas-phase composition, enabling estimation of the gas-phase contribution to the scattering signal while accounting for changes in the gas-phase composition and temperature. We coupled the SAXS measurements with in situ temperature measurements using coherent anti-Stokes Raman spectroscopy. This approach to characterizing the gas-phase SAXS signal provides a physical basis for distinguishing among the contributions to the scattering signal from the instrument function, flame gases, and nanoparticles. The results are particularly important for the analysis of the SAXS signal in the q range associated with particles in the size range of 1-6 nm.

Risk of pre-eclampsia after gastric bypass: a matched cohort study.

OBJECTIVE: To investigate whether gastric bypass before pregnancy is associated with reduced risk of pre-eclampsia. DESIGN: Nationwide matched cohort study. SETTING: Swedish national health care. POPULATION: A total of 843 667 singleton pregnancies without pre-pregnancy hypertension were identified in the Swedish Medical Birth Register between 2007 and 2014, of which 2930 had a history of gastric bypass and a pre-surgery weight available from the Scandinavian Obesity Surgery Registry. Two matched control groups (pre-surgery and early-pregnancy body mass index [BMI]) were propensity score matched separately for nulliparous and parous births, to post-gastric bypass pregnancies (npre-surgery-BMI = 2634:2634/nearly-pregnancy-BMI = 2766:2766) on pre-surgery/early-pregnancy BMI, diabetes status (pre-surgery/pre-conception), maternal age, early-pregnancy smoking status, educational level, height, country of birth, delivery year and history of pre-eclampsia. MAIN OUTCOME MEASURES: Pre-eclampsia categorised into any, preterm onset (<37+0 weeks) and term onset (≥37+0 weeks). RESULTS: In post-gastric bypass pregnancies, mean pre-surgery BMI was 42.9 kg/m2 and mean BMI loss between surgery and early pregnancy was 14.0 kg/m2 (39 kg). Post-gastric bypass pregnancies had lower risk of pre-eclampsia compared with pre-surgery BMI-matched controls (1.7 versus 9.7 per 100 pregnancies; hazard ratio [HR] 0.21, 95% CI 0.15-0.28) and early-pregnancy BMI-matched controls (1.9 versus 5.0 per 100 pregnancies; HR 0.44, 95% CI 0.33-0.60). Although relative risks for pre-eclampsia for post-gastric bypass pregnancies versus pre-surgery matched controls was similar, absolute risk differences (RD) were significantly greater for nulliparous women (RD -13.6 per 100 pregnancies, 95% CI -16.1 to -11.2) versus parous women (RD -4.4 per 100 pregnancies, 95% CI -5.7 to -3.1). CONCLUSION: We found that gastric bypass was associated with lower risk of pre-eclampsia, with the largest absolute risk reduction among nulliparous women. TWEETABLE ABSTRACT: In this large study including two comparison groups matched for pre-surgery or early-pregnancy BMI, gastric bypass was associated with lower risk of pre-eclampsia.

A historical account of the role of exercise in the prevention and treatment of cancer-related lymphedema.

In the absence of guidance from scientific evidence, a range of lymphedema prevention and management, guidelines were developed by relevant organizations around the world. These became publicly available, promoted and endorsed, particularly to women with breast cancer. The recommendations advised avoidance of any activity that could overload or restrict the lymphatic system and need for caution when participating in specific physical activities. However, over the past 20 years evidence has accumulated which has significantly challenged the safety of these recommendations, in particular for those with cancer. There now exists consistent and compelling evidence in support of exercise following a diagnosis of cancer. Participating in exercise during and following cancer treatment improves function and quality of life, reduces treatment-related morbidity, and may improve survival. Further, exercise, including resistance exercise at moderate or high load, is considered safe for those at risk- or with lymphedema. That is, exercise has not been shown to cause or worsen cancer-related lymphedema. This article provides a historical account of the advice given to patients in the prevention and management of lymphedema and how this advice has evolved.

Dual energy 4D-CT of parathyroid adenomas not clearly localized by sestamibi scintigraphy and ultrasonography - a retrospective study.

PURPOSE: At present, the gold standard for diagnosing PAs includes ultrasonography of the neck and sestamibi scans of the parathyroid. The objective of this study was to evaluate scans performed in 4D-DECT (4D-dual-energy mode) at three different time points, in order to analyze spectral information from PAs, lymph nodes (LNs), and thyroid gland (Thy). METHOD: Fifteen patients (mean age: 57 ± 18.9 years) with primary hyperparathyroidism, in which previous ultrasound and sestamibi scanning proved to be negative or equivocal, underwent 4D-DECT in three different phases. Hounsfield units (HU), dual-energy information (electron density [Rho], atomic number [Z], dual-energy index [DEI]), and spectral information (keV) were determined. RESULTS: For all energies, PAs exhibited significantly lower HU-values than the Thy in non-contrast images, and higher HU-values than LNs in the arterial phase (p < 0.05). All three tissues differed significantly in HU in the venous phase at 90 kV, 150 kV, and mixed 0.8 images; the Thy showed significantly higher HU-values than PAs or LNs in non-contrast images at 90 kV, 150 kV, mixed 0.8 images, and [Rho] (p < 0.05). LNs exhibited significantly lower HU-values than PAs and Thy in the arterial phase at 90 kV, 150 kV, mixed 0.8, Rho, Z, and DEI (p < 0.05). With regards to spectral information, lower energies showed greater HU differences between the three tissues. During the venous phase, there were significant differences between all three tissues up to 100 keV (p < 0.05). CONCLUSIONS: We identified significant differences in HU-values and spectral information between PAs, LNs, and Thy at different energies and contrast phases.

Impact of salivary contamination during placement of implants with simultaneous bony augmentation in iliac bone in sheep.

Our aim was to investigate the possible impact of contamination with saliva on osseointegration during placement of implants with simultaneous bone augmentation. Six hemispheric shape bone defects (8mm in diameter×4mm deep) were prepared in each iliac bone of six sheep. A dental implant (2.9mm in diameter×10mm long) was placed in the centre of each defect, and then pairs of defects were filled with one of the following bone augmentation materials: autogenous bone, autogenous bone plus bovine bone, or resorbable biphasic ceramic bone substitute. One site in each augmentation group was impregnated with saliva (contaminated group), while the other was not (non-contaminated group). Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within implant threads were measured after a healing period of five weeks, both in respect of the implant inserted in the augmented bone and in that inserted in the residual bone. Overall results showed that there was a significant difference between the contaminated and non-contaminated group for BIC in the augmented implant (p=0.028), while there were no significant differences in the implant in residual bone (p=0.722). For BAFO, there were no significant differences between the contaminated and non-contaminated groups among the different augmentation materials. The results showed that contamination with saliva during placement of an implant with simultaneous bone augmentation had a serious deleterious effect on osseointegration of the aspect of the implant within the augmented defect. Contamination with saliva during placement of an implant with simultaneous bone augmentation should therefore be avoided.

Maternal and infant pregnancy outcomes in women with psoriatic arthritis: a Swedish nationwide cohort study.

OBJECTIVE: Studies on pregnancy outcomes in psoriatic arthritis (PsA) are scarce and typically of small size. Available studies have reported conflicting results. The aim of this study was to describe maternal and infant pregnancy outcomes among women with PsA compared with women without PsA. DESIGN: Nationwide cohort study. SETTING: Nationwide Swedish registers. POPULATION: A total of 41 485 singleton pregnancies in 1997-2014, of which 541 pregnancies were identified with PsA exposure and 40 944 pregnancies were unexposed. METHODS: By linkage of national health and population register data, we obtained information on individual pregnancies and compared outcomes among pregnancies with PsA and non-PsA pregnancies. Relative risks were estimated by odds ratios (ORs) with 95% CIs using a generalised linear regression model with generalised estimating equations. Adjustments were made for maternal factors and calendar year of birth. MAIN OUTCOME MEASURES: Maternal and infant pregnancy outcomes. RESULTS: Pregnancies to women with PsA had increased risks of preterm birth (adjusted OR 1.63; 95% CI 1.17-2.28), elective and emergency caesarean deliveries (adjusted OR 1.47; 95% CI 1.10-1.97 and adjusted OR 1.43; 95% CI 1.08-1.88, respectively) compared with non-PsA pregnancies. No increased risks were observed for pre-eclampsia, stillbirth or other infant outcomes apart from preterm birth. CONCLUSION: The majority of women with PsA have uneventful pregnancies with respect to adverse outcomes. In the present study, we found increased risks of preterm birth and caesarean delivery compared with non-PsA pregnancies. TWEETABLE ABSTRACT: Women with psoriatic arthritis have uneventful pregnancies but are at increased risk of preterm birth and caesarean delivery.

Impact of surface contamination of implants with saliva during placement in augmented bone defects in sheep calvaria.

Our aim was to try and find out whether contamination with saliva during insertion of dental implants affects osseointegration in bone that has been augmented with different grafts. Six bony defects were created in each of the calvaria of six sheep, and then augmented with three different materials (autogenous bone, bovine bone, and resorbable biphasic ceramic bone substitute) After five weeks of healing, three implants contaminated with saliva (contaminated group) and three not contaminated (uncontaminated group) were placed in the centre of the augmented areas. For histomorphometric analysis, bone implant contact, bone area fraction occupancy, bone and material area, and bony area were measured after a healing period of five weeks. There was a significant difference between the contaminated and uncontaminated groups (p=0.036) for bone implant contact only in the augmented areas, but there were no significant differences in bone area fraction occupancy, bone and material area, and bony area. We conclude that contamination with saliva during placement of dental implants can significantly compromise bone implant contact in augmented areas, but had no significant effect on the formation of bone in areas more distant from the surface of the implant. We suggest that salivary contamination should be avoided during placement of dental implants in augmented areas.

Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth.

Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) are known precursors to high-temperature carbonaceous-particle formation, the molecular pathways that initiate particle formation are unknown. We present experimental and theoretical evidence for rapid molecular clustering-reaction pathways involving radicals with extended conjugation. These radicals react with other hydrocarbon species to form covalently bound complexes that promote further growth and clustering by regenerating resonance-stabilized radicals through low-barrier hydrogen-abstraction and hydrogen-ejection reactions. Such radical-chain reaction pathways may lead to covalently bound clusters of PAHs and other hydrocarbons that would otherwise be too small to condense at high temperatures, thus providing the key mechanistic steps for rapid particle formation and surface growth by hydrocarbon chemisorption.

Pregnancy weight gain by gestational age and stillbirth: a population-based cohort study.

OBJECTIVE: To study the association between total and early pregnancy (<22 completed weeks) weight gain and risk of stillbirth, stratified by early-pregnancy body mass index (BMI). DESIGN: Population-based cohort study. SETTING: Stockholm-Gotland Region, Sweden. POPULATION: Pregnant women with singleton births (n = 160 560). METHODS: Pregnancy weight gain was standardised into gestational age-specific z-scores. For analyses of total pregnancy weight gain, a matched design with an incidence density sampling approach was used. Findings were also contrasted with current Institute of Medicine (IOM) weight gain recommendations. MAIN OUTCOME MEASURES: Stillbirth defined as fetal death at ≥22 completed weeks of gestation. RESULTS: For all BMI categories, there was no statistical association between total or early pregnancy weight gain and stillbirth within the range of a weight gain z-score of -2.0 SD to +2.0 SD. Among normal-weight women, the adjusted odds ratio of stillbirth for lower (-2.0 to -1.0 SD) and higher (+1.0 to +1.9 SD) total weight gain was 0.85 (95% CI; 0.48-1.49) and 1.03 (0.60-1.77), respectively, as compared with the reference category. Further, there were no associations between total or early pregnancy weight gain and stillbirth within the range of weight gain currently recommended by the IOM. For the majority of the BMI categories, the point estimates at the extremes of weight gain values (<-2.0SD and ≥2.0 SD) suggested protective effects of low weight gain and increased risks of high weight gain, but estimates were imprecise and not statistically significant. CONCLUSION: We found no associations between total or early pregnancy weight gain and stillbirth across the range of weight gain experienced by most women. TWEETABLE ABSTRACT: There was no association between weight gain during pregnancy and stillbirth among most women.