Effective density of Aquadag and fullerene soot black carbon reference materials used for SP2 calibration

The mass and effective density of black carbon (BC) particles generated from aqueous suspensions of Aquadag and fullerene soot was measured and parametrized as a function of their mobility diameter. The measurements were made by two independent research groups by operating a differential mobility analyser (DMA) in series with an aerosol particle mass analyser (APM) or a Couette centrifugal particle mass analyser (CPMA). Consistent and reproducible results were found in this study for different production lots of Aquadag, indicating that the effective density of these particles is a stable quantity and largely unaffected by differences in aerosol generation procedures and suspension treatments. The effective density of fullerene soot particles from one production lot was also found to be stable and independent of suspension treatments. Some differences to previous literature data were observed for both Aquadag and fullerene soot at larger particle diameters. Knowledge of the exact relationship between mobility diameter and particle mass is of great importance, as DMAs are commonly used to size-select particles from BC reference materials for calibration of single particle soot photometers (SP2), which quantitatively detect the BC mass in single particles

Comparison of the LEO and CPMA-SP2 techniques for black-carbon mixing-state measurements

It is necessary to measure the mixing states of light-absorbing carbon (LAC) particles to reduce uncertainties in climate forcing due to particulate from wildfires and biomass combustion. For refractory LAC (normally called refractory black carbon; rBC), such measurements can be made using the single particle soot photometer (SP2). The SP2 measures the incandescent mass of individual particles heated by a 1064 nm laser. The SP2 also monitors single-particle light scattering from rBC plus internally mixed material (e.g., coatings of volatile particulate matter). rBC mixing states can be estimated from SP2 measurements by combining the scattering and incandescence signals. This is the basis of the published methods known as (i) scattering–incandescence lag-time, (ii) leading-edge only (LEO), and (iii) normalized derivative methods. More recently, the tandem centrifugal particle mass analyzer–single particle soot photometer (CPMA-SP2) method has been developed. The CPMA-SP2 method does not rely on the SP2 scattering signals and, therefore truly measures the rBC mass fraction, with no assumptions regarding particle composition or morphology. In this study, we provide the first quantitative comparison of the light-scattering and CPMA-SP2 methods for measuring mixing state. We discuss the upper and lower limits of detection (in terms of both rBC and coatings), temporal resolution, role of counting statistics, and errors associated with the measurements. We use a data set of atmospheric particles sampled at a regional background site (Kamloops about 350 km northeast of Vancouver, British Columbia, Canada), where the majority of rBC was emitted by seasonal wildfires. In the overall comparison of measurement methods, the CPMA-SP2 method is found to have significantly better systematic uncertainties than the light-scattering methods for wildfire smoke. For example, the light-scattering methods could not quantify coatings on half of the rBC particles, because their light-scattering signals were below the SP2 detection limit. Consequently, the bias in SP2-only estimates of rBC mixing states depends on the size distribution of the rBC particles. Although more accurate, CPMA-SP2 measurements require significantly more time to acquire, whereas SP2-only light-scattering analyses (both LEO and lag-time) can provide near real-time qualitative information representing large rBC particles.</p

Exercise Improves Vascular Dilator Reactivity in Chronically Stressed Rats with Pre-existing Metabolic Syndrome

Please refer to the pdf version of the abstract located adjacent to the title

Exercise as a Treatment for Peripheral Vascular Dysfunction Caused by Metabolic Syndrome and Depression

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Consumption of Health-Related Content on Social Media Among Adolescent Girls: Mixed-Methods Pilot Study

Background: Consumption of health- and fitness-related social media content is a predominant behavior among teenage girls, which puts them at risk for consuming unreliable health-related information. Objective: This mixed-methods study (qualitative and quantitative) assessed health behavior attitudes and practices as well as social media use among adolescent girls. Additionally, similar practices and behaviors of adults who regularly interact with this population were studied. Methods: Girls aged 12-18 years were recruited to complete a 28-item survey and participate in a 45- to 60-minute focus group. Adults who regularly interact with adolescent girls, including parents, teachers, and healthcare professionals, were recruited from the local community and given a link to provide online consent and complete a survey. Results: A total of 27 adolescent girls participated in one of nine focus groups. Participants included 18 high school (age: mean 16.1 years; SD 1.3 years) and 9 middle school (age: mean 12.4 years; SD 0.7 years) girls. Eleven adults completed the online survey. Adolescents used social media to communicate and connect with friends, rather than as a source of health information. Although adolescents may see health-related content, most do not follow health-related pages or share such pages themselves, and fewer are actively searching for this information. Adolescents tend to trust information from familiar sources, and the participants reported that they do not follow official news accounts. Adults considered modeling and discussing healthy behaviors important and reportedly expected adolescents to see some level of health-related, especially fitness-related, content on social media. Conclusions: Education interventions are warranted for both adolescents and adults with whom adolescent girls regularly interact, in the areas of sedentary behavior to guide them to access reliable online health-related information and be judicious consumers of online health information

Quality of Life Associated with Physical Activity but not Sedentary Time in Youth

Purpose: It has been reported that youth who engaged in more screen time had lower quality of life scores compared to those that were more physically active. Furthermore, increased sedentary behavior increases health risks particularly the risk for obesity. A cross-sectional analysis was completed to examine the relationship between healthrelated quality-of-life (HRQOL) and accelerometer-measured sedentary time (ST) and physical activity (PA) in 9-10-yearold youth who were recruited for the family-based, childhood obesity intervention, iCook 4-H. It was hypothesized that objectively measured ST would be negatively correlated and PA would be positively correlated with HRQOL.Methods: A subset of participants (n=118) wore Actigraph GT3X+ accelerometers for 7 days and completed the Pediatric Quality of Life survey (PedsQLTM, version 4.0) to assess HRQOL. Mean daily minutes of accelerometermeasured ST (547 ± 60) and PA including light-intensity (LPA=240 ± 49), moderate-intensity (MPA=35 ± 11), vigorous-intensity (VPA=17 ± 9), and moderate-to vigorousintensity (MVPA=52 ± 19) were evaluated during waking hours. Multiple linear regressions were used to assess relationship between ST and PA intensities with HRQOL. Statistical significance was set at p ≤ 0.05.Results: There were no significant associations between ST or LPA with HRQOL. MPA, VPA and MVPA were positively associated with multiple HRQOL domains.Conclusion: The lack of relationship between objectively measured ST and LPA with the total HRQOL score and subscales merits further investigation. The findings of the current study support the need for lifestyle interventions that engage families in behavior that increases MVPA

Wettability characteristics of an Al2O3/SiO2-based ceramic modified with CO2, Nd:YAG, excimer and high-power diode lasers

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of an Al2O3/SiO2 based ceramic was found to effect significant changes in the wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330 respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2, Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic increasing after interaction with excimer laser radiation. (iii) the surface oxygen content of the Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation. The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could be controlled and/or modified with laser surface treatment. In particular, whether the laser radiation had the propensity to cause surface melting. However, a wavelength dependance of the change of the wetting properties could not be deduced from the findings of this work

The Effect of iCook 4-H, a Childhood Obesity Prevention Program, on Blood Pressure and Quality of Life in Youth and Adults: A Randomized Control Trial

Objective: Obesity increases the risk of developing hypertension and from population-based samples with estimations that of 2-4% of the U.S. pediatric population has hypertension, which may affect quality of life. This study examined the effects of an obesity prevention program on blood pressure and quality of life in youth and adult participants. Methods: A multi-state research team recruited treatment dyads (youth and their adult meal preparer) to participate in a 12-week randomized control trial and follow-up through 24 months. The treatment group received a cooking and physical activity intervention, followed by booster sessions and mailed newsletters over the remaining two-year period. The control group received no intervention. Resting blood pressure and health related quality of life (HRQOL) surveys were administered at 0,4,12 and 24 months. Results: 228 dyads were recruited (n=77 control and n=151 for treatment). Youth and adult systolic blood pressure (SBP) increased over the 24 months (p=0.003 and p=0.03, respectively) with no differences between groups. From baseline to 24 months both control and treatment youths’ physical and psychological HRQOL increased (p=0.01 and p=0.002, respectively). At 0 and 4 months, youth and adult SBP was positively correlated (r=0.24, p=0.003 and r=0.33, p\u3c0.001, respectively). In the treatment group, there was an inverse association between adult SBP and youth psychological HRQOL at 4 months (r=-0.20, p=0.04), and a similar trend in adult SBP and youth physical HRQOL at 4 months in the treatment group (r=-0.19, p=0.05). Conclusion: A youth-adult dyad obesity prevention program consisting of culinary, mealtime and physical activity education, elicited improvements in HRQOL in youth participants

Enhanced Evaporation of Microscale Droplets With an Infrared Laser

Enhancement of water droplet evaporation by added infrared radiation was modeled and studied experimentally in a vertical laminar flow channel. Experiments were conducted on droplets with nominal initial diameters of 50 lm in air with relative humidities ranging from 0% to 90% RH. A 2800 nm laser was used with radiant flux densities as high as 4 Â 10 5 W/m 2 . Droplet size as a function of time was measured by a shadowgraph technique. The model assumed quasi-steady behavior, a low Biot number liquid phase, and constant gas-vapor phase material properties, while the experimental results were required for model validation and calibration. For radiant flux densities less than 10 4 W/m 2 , droplet evaporation rates remained essentially constant over their full evaporation, but at rates up to 10% higher than for the no radiation case. At higher radiant flux density, the surface-area change with time became progressively more nonlinear, indicating that the radiation had diminished effects on evaporation as the size of the droplets decreased. The drying time for a 50 lm water droplet was an order of magnitude faster when comparing the 10 6 W/m 2 case to the no radiation case. The model was used to estimate the droplet temperature. Between 10 4 and 5 Â 10 5 W/m 2 , the droplet temperature changed from being below to above the environment temperature. Thus, the direction of conduction between the droplet and the environment also changed. The proposed model was able to predict the changing evaporation rates for droplets exposed to radiation for ambient conditions varying from dry air to 90% relative humidity

Comprehensive characterization of mainstream marijuana and tobacco smoke

Abstract: Recent increases in marijuana use and legalization without adequate knowledge of the risks necessitate the characterization of the billions of nanoparticles contained in each puff of smoke. Tobacco smoke offers a benchmark given that it has been extensively studied. Tobacco and marijuana smoke particles are quantitatively similar in volatility, shape, density and number concentration, albeit with differences in size, total mass and chemical composition. Particles from marijuana smoke are on average 29% larger in mobility diameter than particles from tobacco smoke and contain 3.4× more total mass. New measurements of semi-volatile fractions determine over 97% of the mass and volume of the particles from either smoke source are comprised of semi-volatile compounds. For tobacco and marijuana smoke, respectively, 4350 and 2575 different compounds are detected, of which, 670 and 536 (231 in common) are tentatively identified, and of these, 173 and 110 different compounds (69 in common) are known to cause negative health effects through carcinogenic, mutagenic, teratogenic, or other toxic mechanisms. This study demonstrates striking similarities between marijuana and tobacco smoke in terms of their physical and chemical properties