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Objectives. To compare fine particulate matter (PM2.5) concentrations in American Indian (AI)-populated with those in non–AI-populated counties over time (2000–2018) in the contiguous United States. Methods. We used a multicriteria approach to classify counties as AI- or non--AI-populated. We ran linear mixed effects models to estimate the difference in countywide annual PM2.5 concentrations from well-validated prediction models and monitoring sites (modeled and measured PM2.5, respectively) in AI- versus non–AI-populated counties. Results. On average, adjusted modeled PM2.5 concentrations in AI-populated counties were 0.38 micrograms per cubic meter (95% confidence interval [CI] = 0.23, 0.54) lower than in non–AI-populated counties. However, this difference was not constant over time: in 2000, modeled concentrations in AI-populated counties were 1.46 micrograms per cubic meter (95% CI = 1.25, 1.68) lower, and by 2018, they were 0.66 micrograms per cubic meter (95% CI = 0.45, 0.87) higher. Over the study period, adjusted modeled PM2.5 mean concentrations decreased by 2.13 micrograms per cubic meter in AI-populated counties versus 4.26 micrograms per cubic meter in non–AI-populated counties. Results were similar for measured PM2.5. Conclusions. This study highlights disparities in PM2.5 trends between AI- and non–AI-populated counties over time, underscoring the need to strengthen air pollution regulations and prevention implementation in tribal territories and areas where AI populations live. (Am J Public Health. 2022;112(4): 615–623. https://doi.org/10.2105/AJPH.2021.306650 )

Das Konzept des Smart Tourism hat in jüngster Vergangenheit vor allem in Städten zunehmend an Bedeutung gewonnen und das Verhalten sowie die Interaktionen der Akteure erheblich verändert. Der aktuelle Fokus des Smart Tourism auf Städte wird durch praktische Faktoren und die enge Verflechtung mit dem Konzept der Smart City begründet. Die Umsetzung des smarten Städtetourismus ist in der Praxis zwar durch eine Vielzahl an Fallstudien dokumentiert, diese Beschreibungen der smarten Aktivitäten sind jedoch sehr segregiert und idiografisch auf einzelne Städte ausgerichtet. Synoptische Studien fehlen bislang. Dieser Beitrag schließt diese Forschungslücke und vergleicht die Aktivitäten und Entwicklung im Smart Tourism in Städten weltweit.

Many traces of human cultures and activities over the centuries have marked the landscape, but they are often not recognisable at first glance. The recording and inventory of these historical cultural landscape elements, and their associated mapping, serve to raise awareness of—and ultimately also protect and maintain—the cultural landscape. Researchers at the Chair of Human Geography and Transition Research at the University of Augsburg have recorded all preserved and visible elements of the historical cultural landscape in the district of Augsburg that are not currently under monument or nature protection, and which consequently have not yet been mapped for the corresponding cadastre. In a first step, old maps, aerial and satellite images, local chronicles, regional books and other writings were examined. Subsequently, through public participation instruments, such as information events, individual interviews with local people and a hotline, further historical cultural landscape elements were recorded, based on the knowledge of local citizens. As a result, the three-year project was able to identify a total of 613 cultural remnants of various functions, and these were visualised and saved through numerous maps.

ZusammenfassungKleinere Städte außerhalb der Ballungsräume, die in besonderem Maße für Touristen und Besucher interessant sind, sehen sich vielfältigen Herausforderungen ausgesetzt. Dazu zählen beispielsweise Interessenskonflikte zwischen Besuchern und Bewohnern, erhöhtes Verkehrsaufkommen auf engem Raum oder saisonale Schwankungen der Einkommensbasis. Während für ländliche Urlaubsdestinationen wie auch für touristisch geprägte Großstädte bereits zahlreiche Studien und Untersuchungen vorliegen, wurden die spezifischen Anforderungen an Klein- und Mittelstädte mit hohem Tourismusaufkommen bislang kaum von Politik und Wissenschaft thematisiert. Im Rahmen eines Kooperationsprojektes zwischen der Universität Augsburg und der Industrie- und Handelskammer für Schwaben (IHK) wurden daher die spezifischen Probleme und Chancen solcher Standorte identifiziert und verallgemeinerbare Handlungsempfehlungen entwickelt.

We developed a low-cost method for fabricating "soil-on-a-chip" micromodels with 2D and 2.5D pore structures by stacking layers made with a conventional low-cost tabletop CNC router followed by tape bonding. The pore structure was extracted from an X-ray micro-computed tomography scanning image of a medium-grain sandstone sample. The imbibition experiments performed in the 2D and 2.5D micromodels showed the trends of the residual saturation versus capillary number (Ca). The channels showed opposing trends for low-aspect-ratio 2D and high-aspect-ratio 2.5D micromodels. As the channel aspect ratio increased, the location of air entrapment changed from dead-end pores to transport pores. The sizes of trapped air bubbles in the transport pores decreased as the injection flow rates increased. To show the relationship between the air trapped size and Ca, we derived equations that described the competition between the bulk menisci and the corner flow in the channels for different Ca based on the "supply principle." The relative contributions of the piston displacement and corner film flow, which were dependent on the cross-sectional shapes of the pores and Ca, determined the size and location of the air bubbles trapped in the 2.5D micromodel.

BACKGROUND: The waterfront in the South Bronx in New York City is used industrially and harbors the Harlem River Yards (HRY). The HRY borders an environmental justice area, which includes a mixed-use area that is separated from a densely populated residential area by interstates. Recently, development of the HRY has expanded including the 2018 opening of a large online store warehouse. OBJECTIVE: The goal of this study was to evaluate trends in traffic congestion nearby the HRY between 2017 to 2019. METHODS: We analyzed one-hourly time series of crowd-sensed traffic congestion maps, both at the neighborhood scale and the road stretch level. Traffic radar measurements at two locations did not indicate bias in the crowd-sensed data over the study period, i.e., changed mappings between vehicle speed and the reported congestion. RESULTS: In the mixed-use areas, traffic congestion increased significantly during all hours of the day, with greatest increases at night and in the morning. Congestion increased close to the entrances of the HRY and along routes used by pedestrians and bicyclists to access a nearby recreational area. In the residential area, congestion increased significantly from midnight to morning and was unchanged for the remainder of the day. On the interstates, congestion decreased during the daytime but increased at night. CONCLUSIONS: Neighborhood-scale traffic congestion increased in mixed-use and residential areas in an environmental justice community. Our methods can be applied globally as long as crowd-sensed traffic data can be acquired. The data enable communities to advocate for mitigating measures.

Zusammenfassung Ausgelöst durch die pandemiebedingten Veränderungen des Reiseverhaltens untersucht der Lehrstuhl für Humangeographie und Transformationsforschung an der Universität Augsburg in Kooperation mit dem Wissenstransferzentrum Innovative und Nachhaltige Tourismusentwicklung an der Hochschule Kempten elaborierte Formen eines möglichen low touch tourism. Im Fokus stehen dabei wirksame Strategien zur Vermeidung von Gruppenbildungen und Crowding-Effekten, Potentiale zur Minimierung physischer Kontakte zwischen Reisenden und Tourismusanbieter:innen (Techniken zur Vermeidung von near-contact services) und Möglichkeiten zur Reduzierung von physischen Kontakten mit hochfrequentierten Oberflächen. Ziel des Projektes ist die Sammlung, Strukturierung und Kategorisierung von Informationen, Daten und Erfahrungen zum low touch tourism.

The increasing use of electronic nicotine delivery systems (ENDS) is of concern due to multiple emerging adverse health effects. Most analyses of the harmful chemicals of ENDS have targeted metals or carbonyls generated by thermal decomposition of carrier liquids such as propylene glycol. However, new complex compounds not routinely identified and with unknown health consequences could be formed. ENDS aerosol samples were collected by the direct aerosol droplet deposition method. Untargeted analysis was performed using Orbitrap mass spectrometry with high mass accuracy. We identified more than 30 “features” in the aerosol characterized by pairs of the mass-to-charge ratio “ m/ z” of the compound and the retention time. We identified several compounds containing nicotine and propylene glycol (NIC-PG), whose abundance relative to nicotine increased along with vaping power used. On the basis of the prediction by the Environmental Protection Agency Toxicity Estimation Software Tool, these compounds exert developmental toxicity. In addition, a nitrogen-containing compound, likely tributylamine (a known lung irritant), was identified based on the molecular weight. This compound has not been previously identified in ENDS e-liquids and aerosols. ENDS produce not only small toxic compounds such as aldehydes, but also large complex toxic compounds such as NIC-PG. Predicted development toxicity for NIC-PG is concerning for fetal development in pregnant women who use ENDS, children exposed to secondhand or thirdhand ENDS aerosols, and teenage ENDS users whose brains are still developing. The strong positive association between NIC-PG levels and ENDS power output supports regulating high-powered ENDS.

BACKGROUND AND AIM: Fine particulate matter (PM2.5) exposure is associated with increased risk of numerous adverse health outcomes. Prior research shows that PM2.5 is disproportionately concentrate...

In the recent past, a change in consumer behavior has accelerated the change in inner cities: Hybrid consumption is characterized by an “as well as” behavior when shopping. This phenomenon can be researched using the example of an annual passer-by survey in the test city of Augsburg. It turns out that increasingly different motives than shopping are crucial for the inner city visit. Correspondingly, consumer spending is also declining. This is why retail sales are coming under increasing pressure despite the increasing number of visitors.

Background Crowd-sourced traffic data potentially allow prediction of traffic-related air pollution at high temporal and spatial resolution. Objectives To examine associations (1) of radar-based traffic measurements with congestion colors displayed on crowd-sourced traffic data maps and (2) of black carbon (BC) levels with radar and crowd-sourced traffic data. Methods At an off-ramp of an interstate and a small one-way street in a mixed-use area in New York City, we used radar devices to obtain vehicle speeds and flows (hourly counts) for cars and trucks. At these radar sites and at an additional non-radar equipped site at a 2-way street, we monitored BC levels using aethalometers in the summer and early fall of 2017. At all three sites, free-flow traffic conditions typically did not occur due to the nearby presence of traffic lights and forced turns. We also downloaded real-time traffic maps from a crowd-sourced traffic data provider and assigned an ordinal integer congestion color code CCC to the congestion colors, ranging from 1 (dark red) to 5 (gray). Results CCC increased with vehicle speed. Traffic flow was highest for intermediate speeds and intermediate CCC. Regression analyses showed that BC levels increased with either segregated or total vehicle flows. At the off-ramp, time-dependent BC levels can be inferred from time-dependent CCC and radar-derived mean vehicle flow data. A unit decrease in CCC for a mean traffic flow of 100 vehicles/h was associated with a mean (95% CI) increase in BC levels of 0.023 (0.028, 0.018) μg/m3. At the small 1-way and the 2-way street, BC levels were also negatively associated with CCC, though at a >0.05 significance level. Conclusions Use of inexpensive crowd-sourced traffic data holds great promise in air pollution modeling and health studies. Time-dependent traffic-related primary air pollution levels may be inferred from radar-calibrated crowd-sourced traffic data, in our case radar-derived mean traffic flow and widely available CCC data. However, at some locations mean traffic flow data may already be available.

The use of electronic cigarettes (e-cigarettes) has increased due to the belief that they are healthier than tobacco cigarettes. E-cigarettes contain a metallic heating coil (composed of Ni, Cr, Al and other metals) to heat a solution (commonly called e-liquid) and convert it into an aerosol. This aerosol is inhaled (vaped) by the users who can be potentially exposed to a wide variety of metals. We investigated the possible transfer of metals from the coil to the e-liquid and the generated aerosol, and how the exposure to this aerosol can increase metal body burden in e-cigarette users. We recruited 75 e-cigarette users (50 who only vaped and 25 dual users who vaped and smoked) and 25 controls who neither vaped nor smoked. E-liquid samples before (dispenser e-liquid) and after (tank e-liquid) being added to their devices were collected. Aerosol samples were collected using a condensation method. All participants provided urine and hair samples. All samples were analyzed for metals by ICP-MS. We observed higher metal concentrations in the aerosol and tank e-liquid (in contact with the coil) compared to the dispenser e-liquid (before contact with the coil). The median concentrations for some of the metals with the most remarkable increases in aerosol and tank e-liquid vs. dispenser e-liquid were 36.90 and 62.73 vs. 18.29 μg/kg for Al; 6.71 and 28.97 vs. 0.98 μg/kg for Cr; 91.39 and 414.47 vs. 1.64 μg/kg for Ni; 738.99 and 744.24 vs. 16.56 μg/kg for Zn; and 10.17 and 22.31 vs. 0.88 μg/kg for Pb. We also found detectable and potentially high concentrations of other metals such as Mn, Cu, Sb and Sn. In urine, increases in the median levels (μg/g creatinine) in vapers/duals vs. controls were observed for some metals, including Cr (0.34/0.28 vs. 0.20), Cu (1.72/2.36 vs. 1.46), Sn (0.26/0.31 vs. 0.18) and Pb (0.39/0.44 vs. 0.22). In hair, there were no differences in metal concentrations among the three groups. In conclusion, e-cigarettes are likely a source of metals such as Cr, Cu, Ni, Pb or Sn. These metals come from the device, likely the heating resistance, as their concentrations were low in the dispenser e-liquid and higher in the aerosol and the e-liquid left in the tank. Although the exposure to e-cigarette aerosol can have an influence in the body burden of metals, aerosol metal levels were not clearly associated with metal levels in biological samples such as urine or hair in e-cigarette users in this study.

Introduction To mitigate the COVID-19 pandemic and prevent overwhelming the healthcare system, social-distancing policies such as school closure, stay-at-home orders, and indoor dining closure have been utilized worldwide. These policies function by reducing the rate of close contact within populations and result in decreased human mobility. Adherence to social distancing can substantially reduce disease spread. Thus, quantifying human mobility and social-distancing compliance, especially at high temporal resolution, can provide great insight into the impact of social distancing policies. Methods We used the movement of individuals around New York City (NYC), measured via traffic levels, as a proxy for human mobility and the impact of social-distancing policies (i.e., work from home policies, school closure, indoor dining closure etc.). By data mining Google traffic in real-time, and applying image processing, we derived high resolution time series of traffic in NYC. We used time series decomposition and generalized additive models to quantify changes in rush hour/non-rush hour, and weekday/weekend traffic, pre-pandemic and following the roll-out of multiple social distancing interventions. Results Mobility decreased sharply on March 14, 2020 following declaration of the pandemic. However, levels began rebounding by approximately April 13, almost 2 months before stay-at-home orders were lifted, indicating premature increase in mobility, which we term social-distancing fatigue. We also observed large impacts on diurnal traffic congestion, such that the pre-pandemic bi-modal weekday congestion representing morning and evening rush hour was dramatically altered. By September, traffic congestion rebounded to approximately 75% of pre-pandemic levels. Conclusion Using crowd-sourced traffic congestion data, we described changes in mobility in Manhattan, NYC, during the COVID-19 pandemic. These data can be used to inform human mobility changes during the current pandemic, in planning for responses to future pandemics, and in understanding the potential impact of large-scale traffic interventions such as congestion pricing policies., Graphical abstract Unlabelled Image

PURPOSE OF REVIEW: Electronic cigarettes (e-cigs) are a source of metals. Epidemiologic and experimental evidence support that metals are toxic to the cardiovascular system. Little is known, however, about the role that e-cig metals may play as toxicants for the possible cardiovascular effects of e-cig use. The goal of this narrative review is to summarize the evidence on e-cig use and metal exposure and on e-cig use and cardiovascular toxicity and discuss the research needs. RECENT FINDINGS: In vitro studies show cytotoxicity and increased oxidative stress in myocardial cells and vascular endothelial cells exposed to e-liquids and e-cig aerosols, with effects partially reversed with antioxidant treatment. There is some evidence that the heating coil plays a role in cell toxicity. Mice exposed to e-cigs for several weeks showed higher levels of oxidative stress, inflammation, platelet activation, and thrombogenesis. Cross-over clinical experiments show e-cig use alters nitric oxide-mediated flow-mediated dilation, endothelial progenitor cells, and arterial stiffness. Cross-sectional evidence from large nationally representative samples in the US support that e-cig use is associated with self-reported myocardial infarction. Smaller studies found associations of e-cig use with higher oxidized low-density protein and heart variability compared to healthy controls. Numerous studies have measured elevated levels of toxic metals in e-cig aerosols including lead, nickel, chromium and manganese. Arsenic has been measured in some e-liquids. Several of these metals are well known to be cardiotoxic. SUMMARY: Numerous studies show that e-cigs are a source of cardiotoxic metals. Experimental studies (in vitro, in vivo, and clinical studies) show acute toxicity of e-cigs to the vascular system. Studies of long-term toxicity in animals and humans are missing. Longitudinal studies with repeated measures of metal exposure and subclinical cardiovascular outcomes (e.g. coronary artery calcification) could contribute to determine the long-term cardiovascular effects of e-cigs and the potential role of metals in those effects.

PURPOSE: During gas station operation, unburned fuel can be released to the environment through distribution, delivery, and storage. Due to the toxicity of fuel compounds, setback distances have been implemented to protect the general population. However, these distances treat gasoline sales volume as a categorical variable and only account for the presence of a single gas station and not clusters, which frequently occur. This paper introduces a framework for recommending setback distances for gas station clusters based on estimated lifetime cancer risk from benzene exposure. METHODS: Using the air quality dispersion model AERMOD, we simulated levels of benzene released to the atmosphere from single and clusters of generic gas stations and the associated lifetime cancer risk under meteorological conditions representative of Albany, New York. RESULTS: Cancer risk as a function of distance from gas station(s) and as a continuous function of total sales volume can be estimated from an equation we developed. We found that clusters of gas stations have increased cancer risk compared to a single station because of cumulative emissions from the individual gas stations. For instance, the cancer risk at 40 m for four gas stations each dispensing 1 million gal/year is 9.84 × 10(−6) compared to 2.45 × 10(−6) for one gas station. CONCLUSION: The framework we developed for estimating cancer risk from gas station(s) could be adopted by regulatory agencies to make setback distances a function of sales volume and the number of gas stations in a cluster, rather than on a sales volume category. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40201-020-00601-w.

Hypothesis, Identification and quantification of harmful chemicals in e-cigarette aerosol requires collecting the aerosolized e-liquid for chemical analysis. In 2016, Olmedo at al. empirically developed a simple method for aerosol collection by directing the aerosol through a sequence of alternating straight and converging tubing sections, which drain the recovered e-liquid into a collection vial. The tubing system geometry and flow conditions promote inertial impaction of aerosolized e-liquid on tube walls, where it deposits and flows into the collection vial., Experiments, We use high-speed optical imaging to visualize aerosol transport in proxies of the collection system. We also determined collection efficiencies of various configurations of the collection system., Findings, A turbulent jet emerges from converging conical sections and impinges onto the wall of downstream tubing sections, resulting in inertial impaction and deposition of the aerosol. For inertial impaction to occur the tip radius of the converging section must be small enough for a jet to be formed and the sequence of tubing sections must be curved in a polygon-like manner such that the jet emerging from a converging section impinges on the downstream tube wall. The collection efficiency is significantly smaller without such curvature.

Mott Haven, a low-income neighborhood in New York City, suffers from increased air pollution and accommodates several industrial facilities and interstates. In 2018, a large delivery service warehouse opened. Our objectives are to characterize black carbon (BC), fine particulate matter (PM2.5), and noise in the community, model changes in traffic due to the facility opening, and estimate associated BC and noise changes. BC, PM2.5, and noise were measured at eight sites pre-opening, and traffic counted continuously at two sites (June 2017-May 2019). An interrupted time series model was used to determine facility-related changes in traffic. Post-opening changes in traffic-related BC/noise were estimated from regressions of BC/noise with traffic flow. Mean (SD) pre-warehouse measures of BC and PM2.5 were 1.33 &micro, g/m3 (0.41) and 7.88 &micro, g/m3 (1.24), respectively. At four sites, equivalent sound levels exceeded the EPA&rsquo, s recommended 70 dBA limit. After the warehouse opening, traffic increased significantly, predominantly at night. At one site, the greatest change for trucks occurred 9PM-12AM: 31.7% (95%CI [23.4%, 40.6%]). Increased traffic translated into mean predicted increases of 0.003 &micro, g/m3 (BC) and 0.06 dBA (noise). Though small, they negate the substantial decrease the community seeks. Our findings can help communities and policymakers better understand impacts of traffic-intensive facilities.

Background: Electronic cigarettes (e-cigarettes) have become popular, in part because they are perceived as a safer alternative to tobacco cigarettes. An increasing number of studies, however, have found toxic metals/metalloids in e-cigarette emissions. Results: We identified 24 studies on metals/metalloids in e-liquid, e-cigarette aerosols, and human biosamples of e-cigarette users. Metal/metalloid levels, including aluminum, antimony, arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel, selenium, tin, and zinc, were present in e-cigarette samples in the studies reviewed. Twelve studies reported metal/metalloid levels in e-liquids (bottles, cartridges, open wick, and tank), 12 studies reported metal/metalloid levels in e-cigarette aerosols (from cig-a-like and tank devices), and 4 studies reported metal/metalloid levels in human biosamples (urine, saliva, serum, and blood) of e-cigarette users. Metal/metalloid levels showed substantial heterogeneity depending on sample type, source of e-liquid, and device type. Metal/metalloid levels in e-liquid from cartridges or tank/open wicks were higher than those from bottles, possibly due to coil contact. Most metal/metalloid levels found in biosamples of e-cigarette users were similar or higher than levels found in biosamples of conventional cigarette users, and even higher than those found in biosamples of cigar users. Conclusion: E-cigarettes are a potential source of exposure to metals/metalloids. Differences in collection methods and puffing regimes likely contribute to the variability in metal/metalloid levels across studies, making comparison across studies difficult. Standardized protocols for the quantification of metal/metalloid levels from e-cigarette samples are needed., This study was supported by NIEHS/FDA grants R21ES029777 and R01ES030025, NIEHS grant P30ES009089, and a Johns Hopkins University Technology Transfer Seed Award. D. Z. was supported by the China Scholarship Council (201706190116). A. A. was supported by a grant from the MD Cigarette Restitution Fund (grantPHPA-G2034).

Wahrend die Festivalisierung und Inszenierung von Innenstadten in Ballungsraumen relativ gut erforscht und beschrieben ist, liegen vergleichsweise wenige Erkenntnisse uber die Rolle innerstadtischer Events im landlichen Raum vor. Auch die Frage, wie dort der lokale Einzelhandel von solchen Veranstaltungen profitiert und wie sie fur ihn einen wirklichen Mehrwert bringen, wurde erst vereinzelt untersucht. Da viele Kleinstadte im landlichen Raum aber mit vergleichbaren Herausforderungen konfrontiert sind (z. B. sinkende Frequentierung, veranderte Erwartungshaltungen der Passanten und Bewohner, Online-Handel, Leerstande etc.), identifiziert dieser Artikel praktikable und effiziente Event-Strategien fur Zentren im landlichen Raum, um diesen Herausforderungen zukunftig gezielt begegnen zu konnen.

Vaping is the action of inhaling and exhaling aerosols from electronic cigarettes. The aerosols contain various amounts of toxic chemicals, including metals. The purpose of this study was to evaluate factors that can influence metal levels, including flavor and nicotine content in the e-liquid, and puff duration. Aerosols were collected from both closed-system (cartridge-based) and open-system e-cigarettes using e-liquids with different flavors (fruit, tobacco, and menthol), nicotine content (0, 6, 24, and 59 mg/mL), and different puff durations (1, 2, and 4 s). The concentrations of 14 metals in the collected aerosols were measured using inductively coupled plasma mass spectroscopy. Aerosol concentrations of As, Fe, and Mn varied significantly among fruit, tobacco, and menthol flavors in both closed-system and open-system devices. Concentrations of Al, Fe, Sn, and U were significantly higher in tobacco or menthol flavored aerosols compared to fruit flavors in closed-system devices. Aerosol W levels were significantly higher in tobacco flavored aerosols compared to fruit flavors in open-system devices. Concentrations of As, Fe, and Mn were higher in tobacco flavored aerosols compared to menthol flavors in both types of devices. The median Pb concentration decreased significantly from 15.8 to 0.88 μg/kg when nicotine content increased from 0 to 59 mg/mL, and median Ni concentration was 9.60 times higher in aerosols with nicotine of 59 mg/mL compared to 24 mg/mL (11.9 vs. 1.24 μg/kg) for closed-system devices. No significant differences were observed in aerosol metal concentrations for different puff durations. Aerosol metal concentrations varied widely between different flavors and nicotine content but not by puff duration. Flavor and nicotine content of the e-liquid could be potential factors in metal emissions. Some elements showed higher concentrations under certain conditions, highlighting the urgent need of developing strict product regulations, especially on e-liquid composition and nicotine content to inform e-cigarette users about metal exposure through vaping.

Microscale water distribution in the subsurface is key to many geochemical and biogeochemical reactions. This study investigated microscale water distribution and movement in unsaturated soils using micro-continuum hydrodynamic models, and examined the effect of microscale water distribution on organic carbon (C) decomposition using a micro-continuum biogeochemical reaction model. The micro-continuum hydrodynamic model that relates capillary pressure to porosity captured the measured water imbibition curve at the core scale, and exhibited reasonable water distribution and movement at the microscale. The simulations of organic C decomposition illustrate that microscale water distribution strongly affected the distribution of C decomposition rates by regulating the availability of dissolved organic C and oxygen. Particularly, changes in water distribution altered the location and intensity of reactive hotspots and thereby CO2 flux from soils. The microscale interactions between water content and organic C decomposition rate provide underlying mechanisms for explaining macroscale phenomenon observed in laboratory and fields. Overall, this study presents a useful tool for explicating hydro-biogeochemical behaviors in the subsurface by integrating micro-continuum hydrodynamic and biogeochemical reaction modeling.

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

The lattice Boltzmann method (LBM) based on single-relaxation-time (SRT) or multiple-relaxation-time (MRT) collision operators is widely used in simulating flow and transport phenomena. The LBM based on two-relaxation-time (TRT) collision operators possesses strengths from the SRT and MRT LBMs, such as its simple implementation and good numerical stability, although tedious mathematical derivations and presentations of the TRT LBM hinder its application to a broad range of flow and transport phenomena. This paper describes the TRT LBM clearly and provides a pseudocode for easy implementation. Various transport phenomena were simulated using the TRT LBM to illustrate its applications in subsurface environments. These phenomena include advection-diffusion in uniform flow, Taylor dispersion in a pipe, solute transport in a packed column, reactive transport in uniform flow, and bacterial chemotaxis in porous media. The TRT LBM demonstrated good numerical performance in terms of accuracy and stability in predicting these transport phenomena. Therefore, the TRT LBM is a powerful tool to simulate various geophysical and biogeochemical processes in subsurface environments.

Experimental studies have shown that the modified Green-Ampt (GA) model, which accounts for a velocity-dependent capillary pressure, can describe water infiltration into dry sand columns better than the classical GA model. In this study, we performed a series of downward water infiltration experiments in prewetted sand columns for four different initial water contents (0, 3.3, 6.5 and 13.8%) and three different ponding heights (10, 20 and 40 cm). As expected, an increase in ponding height resulted in a monotonic increase in the infiltration rate. The infiltration rate decreased monotonically as the initial water content increased for initial water contents of 3.3, 6.5 and 13.8%. However, the infiltration rate in the dry sand columns was significantly smaller than in the prewetted sand columns. We linked this anomalous behavior to the strong dynamic effect of the capillary pressure on water infiltration into dry sand columns. The series of downward infiltration experiments were modeled by both the classical and modified GA models. The modified GA model can describe better the experimental results than the classical GA model for infiltration into both dry and prewetted sand columns. The modeling and parameter fitting results show that the magnitude of the dynamic effect on the capillary pressure depends on the initial water content and decreases exponentially as the initial water content increases. Consequently, the classical GA model significantly underestimates the equilibrium suction heads for the infiltration experiments in the dry sand columns.

Colloid transport in saturated porous media is significantly influenced by colloidal interactions with grain surfaces. Near-surface fluid domain colloids experience relatively low fluid drag and relatively strong colloidal forces that slow their down-gradient translation relative to colloids in bulk fluid. Near surface fluid domain colloids may re-enter into the bulk fluid via diffusion (nanoparticles) or expulsion at rear flow stagnation zones, they may immobilize (attach) via primary minimum interactions, or they may move along a grain-to-grain contact to the near surface fluid domain of an adjacent grain. We introduce a simple model that accounts for all possible permutations of mass transfer within a dual pore and grain network. The primary phenomena thereby represented in the model are mass transfer of colloids between the bulk and near-surface fluid domains and immobilization. Colloid movement is described by a Markov chain, i.e., a sequence of trials in a 1D network of unit cells, which contain a pore and a grain. Using combinatorial analysis, which utilizes the binomial coefficient, we derive the residence time distribution, i.e., an inventory of the discrete colloid travel times through the network and of their probabilities to occur. To parameterize the network model, we performed mechanistic pore-scale simulations in a single unit cell that determined the likelihoods and timescales associated with the above colloid mass transfer processes. We found that inter-grain transport of colloids in the near surface fluid domain can cause extended tailing, which has traditionally been attributed to hydrodynamic dispersion emanating from flow tortuosity of solute trajectories.

We examined the effects of acoustic excitations on the water retention curve, i.e., the relationship between capillary pressure (PC) and water saturation (SW) in unsaturated porous media, during drainage. The water retention curves were measured under static and dynamic conditions, where water was withdrawn from a sandbox with three different pumping rates, 12.6, 19.7, and 25.2 mL/s. Excitations with frequencies of 75, 100, 125, and 150 Hz were applied. The acoustic excitations had no effect on the static water retention curve but altered the dynamic water retention curve. The acoustic excitations lowered the dynamic PC, especially under the dynamic condition where the pumping rate was 25.2 mL/s and when SW varied between 0.6 and 0.95. The differences between the capillary pressures measured under static and dynamic conditions decreased when acoustic excitations were applied. We link this finding to the change in contact angle induced by the acoustic excitation. The dynamic coefficients, τ, for the dynamic water retention curves that we fitted to the experimental data were smaller with than without acoustic excitations. We attribute the decrease of the dynamic coefficient to the combination of the increase in the permeability and the decline in the air-entry pressure caused by adding acoustic excitations.

OBJECTIVES: To (1) design and build a low-cost exposure chamber system for whole-body exposure of rodents to electronic cigarette aerosol, (2) provide detailed instructions with particular focus on automated e-cigarette activation, and (3) develop a simple mathematical model for aerosol levels in the exposure chamber. METHODS: We built the system with standard laboratory equipment and an open-source electronics platform (Arduino) for e-cigarette activation. Arduino is used to control a solenoid, which pushes the activation button of so-called “Mod” e-cigarettes, and a pump to move the aerosol from the mouthpiece of the e-cigarette into the chamber. For “Pods” and “Cigalikes,” the solenoid is not used as they are activated by the vacuum created by the pump. Aerosol concentrations were measured with a light-scattering laser photometer. RESULTS: The system allows varying the air exchange rate, monitoring aerosol levels, and programming arbitrary puff topography. Aerosol concentrations observed for different chamber operating conditions (puff time and period, e-cigarette power output, air exchange rate) were consistent with the mathematical model. CONCLUSIONS: Our low-cost exposure chamber can be used in animal experimental studies of the health effects of e-cigarettes. Our model allows estimating design parameters such as chamber volume, air exchange rate, and puff period.

Background Electronic cigarettes (E-cigarettes) generate aerosol containing metal contaminants. Our goals were to quantify aerosol metal concentrations and to compare the effects of power setting and device type (closed-system vs. open-system) on metal release. Methods Aerosol samples were collected from two closed-system devices (a cigalike and pod) and two open-system devices (mods). Each open-system device was operated at three different power settings to examine the effect of device power on metal release. Concentrations of 14 metals in e-cigarette aerosol collected via droplet deposition were measured using inductively coupled plasma mass spectroscopy. Aerosol metal concentrations were reported as mass fractions (μg/kg) in the e-liquid. Results For open-system device 1 (OD1), median arsenic (As), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), and zinc (Zn) concentrations increased 14, 54, 17, 30, 41, 96, 14, 81, 631, and 7-fold when the device power was increased from low (20 W) to intermediate (40 W) setting. When the power was further increased from intermediate (40 W) to high (80 W) setting, concentrations of As, Cr, Cu, Mn, Ni, and Sb did not change significantly. For open-system device 2 (OD2), Cr and Mn concentrations increased significantly when device power was increased from low (40 W) to intermediate (120 W) setting, and then decreased significantly when power was further increased from intermediate (120 W) to high (200 W) setting. Among the four devices, aerosol metal concentrations were higher for the open-system than the closed-system devices, except for aluminum (Al) and uranium (U). For Cr, median (interquartile range) concentrations (μg/kg) from the open-system devices were 2.51 (1.55, 4.23) and 15.6 (7.88, 54.5) vs. 0.39 (0.05, 0.72) and 0.41 (0.34, 0.57) for the closed-system devices. For Ni, concentrations (μg/kg) from the open-system devices were 793 (508, 1169) and 2148 (851, 3397) vs. 1.32 (0.39, 3.35) and 11.9 (10.7, 22.7) from the closed-system devices. Inhalation of 0% and 100% of samples from OD1, 7.4% and 88.9% from OD2 by typical e-cigarette users would exceed chronic minimum risk levels (MRL) of Mn and Ni, respectively. No MRL exceedance was predicted for the closed-system devices. A large fraction of users of OD1 (100%) and OD2 (77.8%) would be exposed to Ni levels higher than those from reference tobacco cigarette 3R4F. Conclusions Our findings suggest that power setting and device type affect metal release from devices to aerosol which would subsequently be inhaled by users. Metal concentrations from open-system devices first increased with device power, and then leveled off for most metals. Open-system devices generate aerosol with higher metal concentrations than closed-system devices. These findings inform tobacco regulatory science, policy makers and health professionals on potential metal health risks associated with e-cigarette use, design and manufacturing.

Zusammenfassung Zahlreiche Kulturlandschaften, die maßgeblich von religiösen Bauwerken, Traditionen oder Riten geprägt sind, nutzen in ihrem touristischen Marketing diese Besonderheiten und entwickeln darauf basierend eine regionale Marke mit eigenem Namen, Logo und Webauftritt. Die Zielgruppe umfasst dabei sowohl religiöse wie auch nicht-religiöse Menschen, weshalb die sakrale Landschaft im Zuge des Brandingprozesses auf jene Facetten reduziert wird, die auch für nicht-religiöse Besucher als interessant erachtet werden. Dadurch wird die regionale Marke nicht nur manipuliert, sondern verliert häufig auch ihre Einzigartigkeit. Die Kommodifizierung wertet die sakrale Landschaft letztlich also nicht auf, sondern opfert ihre unique selling proposition (USP) dem vermuteten Massenmarkt, wodurch der Sinn einer Marke aber fallweise in Frage gestellt wird.