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A list of authors and their affiliations appears at the end of the paper New-particle formation is a major contributor to urban smog 1 , 2 , but how it occurs in cities is often puzzling 3 . If the growth rates of urban particles are similar to those found in cleaner environments (1–10 nanometres per hour), then existing understanding suggests that new urban particles should be rapidly scavenged by the high concentration of pre-existing particles. Here we show, through experiments performed under atmospheric conditions in the CLOUD chamber at CERN, that below about +5 degrees Celsius, nitric acid and ammonia vapours can condense onto freshly nucleated particles as small as a few nanometres in diameter. Moreover, when it is cold enough (below −15 degrees Celsius), nitric acid and ammonia can nucleate directly through an acid–base stabilization mechanism to form ammonium nitrate particles. Given that these vapours are often one thousand times more abundant than sulfuric acid, the resulting particle growth rates can be extremely high, reaching well above 100 nanometres per hour. However, these high growth rates require the gas-particle ammonium nitrate system to be out of equilibrium in order to sustain gas-phase supersaturations. In view of the strong temperature dependence that we measure for the gas-phase supersaturations, we expect such transient conditions to occur in inhomogeneous urban settings, especially in wintertime, driven by vertical mixing and by strong local sources such as traffic. Even though rapid growth from nitric acid and ammonia condensation may last for only a few minutes, it is nonetheless fast enough to shepherd freshly nucleated particles through the smallest size range where they are most vulnerable to scavenging loss, thus greatly increasing their survival probability. We also expect nitric acid and ammonia nucleation and rapid growth to be important in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and nitric acid is abundant from electrical storms 4 , 5 . Measurements in the CLOUD chamber at CERN show that the rapid condensation of ammonia and nitric acid vapours could be important for the formation and survival of new particles in wintertime urban conditions, contributing to urban smog.

In the present-day atmosphere, sulfuric acid is the most important vapour for aerosol particle formation and initial growth. However, the growth rates of nanoparticles (<10 nm) from sulfuric acid remain poorly measured. Therefore, the effect of stabilizing bases, the contribution of ions and the impact of attractive forces on molecular collisions are under debate. Here, we present precise growth rate measurements of uncharged sulfuric acid particles from 1.8 to 10 nm, performed under atmospheric conditions in the CERN (European Organization for Nuclear Research) CLOUD chamber. Our results show that the evaporation of sulfuric acid particles above 2 nm is negligible, and growth proceeds kinetically even at low ammonia concentrations. The experimental growth rates exceed the hard-sphere kinetic limit for the condensation of sulfuric acid. We demonstrate that this results from van der Waals forces between the vapour molecules and particles and disentangle it from charge–dipole interactions. The magnitude of the enhancement depends on the assumed particle hydration and collision kinetics but is increasingly important at smaller sizes, resulting in a steep rise in the observed growth rates with decreasing size. Including the experimental results in a global model, we find that the enhanced growth rate of sulfuric acid particles increases the predicted particle number concentrations in the upper free troposphere by more than 50 %.

Large airports are a major source of ultrafine particles, which spread across densely populated residential areas, affecting air quality and human health. Jet engine lubrication oils are detectable in aviation-related ultrafine particles, however, their role in particle formation and growth remains unclear. Here we show the volatility and new-particle-formation ability of a common synthetic jet oil, and the quantified oil fraction in ambient ultrafine particles downwind of Frankfurt International Airport, Germany. We find that the oil mass fraction is largest in the smallest particles (10-18 nm) with 21% on average. Combining ambient particle-phase concentration and volatility of the jet oil compounds, we determine a lower-limit saturation ratio larger than 1 × 10 5 for ultra-low volatility organic compounds. This indicates that the oil is an efficient nucleation agent. Our results demonstrate that jet oil nucleation is an important mechanism that can explain the abundant observations of high number concentrations of non-refractory ultrafine particles near airports.

Attention has recently been given to the role of race in many aspects of the research process; however, minimal has been written to critique the role of race in qualitative fieldnotes. This gap creates potential conflicts about representation that can exclude marginalized communities and call into question findings when race is ignored in the research process. To successfully address potential investigator biases with a lens towards social justice and equity in healthcare, a critique of foundational methods is required. Here we posit that a qualitative health researchers’ primary tool is their fieldnotes because they contextualize findings and serve as a method to learn through systematic interpretation of local meanings revealed by participants. Here, we provide researchers guidance for teaching and writing fieldnotes that speak to current nuances of observations and interactions with participants. Definitions related to race and ethnicity, the importance of applying appropriate sensitizing frameworks, followed by a discussion of how to use fieldnotes in findings are covered. We include (1) a call for more preparation of novice researchers and a challenge for established researchers to update expertise for collecting and using fieldnotes in the research process, (2) guidance on negotiating difficult situations, and (3) the significance of language in creating credibility in findings when addressing race in qualitative research.

Introducción: El cáncer es una de las principales causas de morbilidad y mortalidad en el mundo, según la Organización Mundial de la Salud (OMS), en 2012 14 millones de casos nuevos y 8,2 millones de muertes. Se demostró que los pacientes en tratamiento, cirugía, quimioterapia y radioterapia tienen niveles altos de cortisol que influye en su calidad de vida. Objetivo: Identificar la relación entre el estrés, a nivel de cortisol y las estrategias de afrontamiento en pacientes con cáncer sometidos a tratamiento.Material y métodos: Estudio transversal, descriptivo y correlacional realizado junio a diciembre del 2019. Resultados epidemiológicos: 68.2% mujeres 31.8 % hombres, entre 17 y 76 años, con diagnósticos de: Ca mama (30.3%), de próstata (18.3), colon (15.2), pulmón (13.6), cervical (12.1% gástrico (9.1%) cáncer de piel (1.5%). Estadísticos: El 35,3% informaron cortisol a niveles normales y 64.5% niveles altos; el estrés obtuvo un promedio de 13.9 (DE = 4.64). Sobre el nivel de cortisol y el tipo de tratamiento, se observaron diferencias significativas (X2 = 1,546, p = .04), es decir, el paciente que tienen un tratamiento mixto el cortisol es más alto. Conclusiones: Es importante reevaluar las estrategias centradas en el problema, analizar implicaciones y proponer estudios en el contexto en que se desenvuelven, en futuro desarrollar una intervención incluyendo actividades de enfermería en la quimioterapia y radioterapia, apoyando estrategias de afrontamiento efectivas. En este sentido y derivado de la minimización de amenazas centradas en el problema, es importante tener un enfoque integral más profundo. Introduction: Cancer is one of the leading causes of morbidity and mortality worldwide, according to the World Health Organization (WHO), in 2012 14 million new cases and 8.2 million deaths. (WHO, 2019). Patients in treatment, surgery, chemotherapy and radiation therapy have been shown to have high levels of cortisol that influence their quality of life. Objective: to identify the relationship between stress, cortisol level and coping strategies in cancer patients undergoing treatment. Material and methods: Cross-sectional, descriptive and correlational study conducted June to December 2018. In 65 male and female patients under treatment. Results: 68.2% were women 31.8% men, between 17 and 76 years. With diagnoses Ca breast (30.3%), prostate cancer (18.3), colon (15.2), lung (13.6), cervical (12.1% gastric (9.1%) skin cancer (1.5%). Statistics: 35.3% reported cortisol at normal levels and 64.5% high levels; stress averaged 13.9 (DE s 4.64). On the level of cortisol and the type of treatment, significant differences were observed (X2 x 1,546, p .04), i.e. the patient who has a mixed treatment cortisol is higher. Conclusions: It is important to reevaluate the strategies focused on the problem, analyze implications and propose studies in the context in which they operate, in the future develop an intervention including nursing activities in chemotherapy and radiotherapy, supporting effective coping strategies. minimizing threats focused on the problem, it is important to have a deeper comprehensive approach.

Iodine is a reactive trace element in atmospheric chemistry that destroys ozone and nucleates particles. Iodine emissions have tripled since 1950 and are projected to keep increasing with rising O3 surface concentrations. Although iodic acid (HIO3) is widespread and forms particles more efficiently than sulfuric acid, its gas-phase formation mechanism remains unresolved. Here, in CLOUD atmospheric simulation chamber experiments that generate iodine radicals at atmospherically relevant rates, we show that iodooxy hypoiodite, IOIO, is efficiently converted into HIO3 via reactions (R1) IOIO + O3 → IOIO4 and (R2) IOIO4 + H2O → HIO3 + HOI + (1)O2. The laboratory-derived reaction rate coefficients are corroborated by theory and shown to explain field observations of daytime HIO3 in the remote lower free troposphere. The mechanism provides a missing link between iodine sources and particle formation. Because particulate iodate is readily reduced, recycling iodine back into the gas phase, our results suggest a catalytic role of iodine in aerosol formation.Iodic acid (HIO3) forms aerosols very efficiently, but its gas-phase formation mechanism is not well understood. Atmospheric simulation chamber experiments, quantum chemical calculations and kinetic modelling have now revealed that HIO3 forms as an early iodine oxidation product from hypoiodite. The mechanism explains field measurements and suggests a catalytic role for iodine in particle formation.

Atmospheric particles play an important role in the radiative balance of the Earth, as well as they affect human health and air quality. Hence, the chemical characterization constitutes a crucial task to determinate their properties, sources and fate. Particularly, the analysis of nanoparticles (d<100 nm) represents an analytical challenge, since these particles are abundant in number but have very little mass.This accumulative thesis focuses on the chemical characterization of nanoparticles, performed in both laboratory and field studies. Here, I present four manuscripts, two of which are my main project as a lead author. The first manuscript (Caudillo et al., 2021) focuses on the gas and the particle phase originated from biogenic precursor gases (α-pinene and isoprene). The experiments were performed in the CLOUD chamber at CERN to simulate pure biogenic new particle formation. Both gas and particle phases are measured with a nitrate CI-APi-TOF mass spectrometer, while the TD-DMA is coupled to it for particle-phase measurements, this setup allows a direct comparison as both measurements use the identical chemical ionization and detector. This study demonstrates the suitability of the TD-DMA for measuring newly formed nanoparticles and it confirms that isoprene suppresses new particle formation but contributes to the growth of newly formed particles.The second manuscript (Caudillo et al., 2022) presents an intercomparison of four different techniques (including the TD-DMA) for measuring the chemical composition of SOA nanoparticles. The measurements were conducted in the CLOUD chamber. The intercomparison was done by contrasting the observed chemical composition, the calculated volatility, and the thermal desorption behavior (for the thermal desorption techniques). The methods generally agreed on the most important compounds that are found in the nanoparticles. However, they did see different parts of the organic spectrum. Potential explanations for these differences are suggested.The third manuscript (Ungeheuer al., 2022) presents both laboratory and ambient measurements to investigate the ability of lubricant oil to form new particles. These new particles are an important source of ultrafine particles in the areas nearby large airports. The ambient measurements were performed downwind of Frankfurt International Airport, and it was found that the fraction of lubricant oil is largest in the smallest particles. In the laboratory, the main finding was that evaporated lubricant oil nucleates and forms new particles rapidly. The results suggest that nucleation of lubricant oil and subsequent particle growth can occur in the cooling exhaust plumes of aircraft-turbofans.The fourth manuscript (Wang et al., 2022) is a new particle formation study in the CLOUD chamber at CERN. This study shows that nitric acid, sulfuric acid, and ammonia interact synergistically and rapidly form particles under upper free tropospheric conditions. These particles can grow by condensation (driven by the availability of ammonia) up to CCN sizes and INP particles. The ability of these particles to act as a CCN and INP was also investigated and it was found to be as efficient as for desert dust. This mechanism constitutes an important finding and it can account for previous observations of high concentrations of ammonia and ammonium nitrate over the Asia monsoon region.

Isoprene (C 5 H 8 ) is the non-methane hydrocarbon with the highest emissions to the atmosphere. It is mainly produced by vegetation, especially broad-leaved trees, and efficiently transported to the upper troposphere in deep convective clouds, where it is mixed with lightning NO x . Isoprene oxidation products drive rapid formation and growth of new particles in the tropical upper troposphere. However, isoprene oxidation pathways at low temperatures are not well understood. Here, in experiments at the CERN CLOUD chamber at 223 K and 243 K, we find that isoprene oxygenated organic molecules (IP-OOM) all involve two successive OH ∙ oxidations. However, depending on the ambient concentrations of the termination radicals ( HO 2 ∙ , NO ∙ , and NO 2 ∙ ), vastly-different IP-OOM emerge, comprising compounds with zero, one or two nitrogen atoms. Our findings indicate high IP-OOM production rates for the tropical upper troposphere, mainly resulting in nitrate IP-OOM but with an increasing non-nitrate fraction around midday, in close agreement with aircraft observations. Experiments under upper-tropospheric conditions map the chemical formation of isoprene oxygenated organic molecules (important molecules for new particle formation) and reveal that relative radical ratios control their composition

New particle formation in the upper free troposphere is a major global source of cloud condensation nuclei (CCN) . However, the precursor vapours that drive the process are not well understood. With experiments performed under upper tropospheric conditions in the CERN CLOUD chamber, we show that nitric acid, sulfuric acid and ammonia form particles synergistically, at rates that are orders of magnitude faster than those from any two of the three components. The importance of this mechanism depends on the availability of ammonia, which was previously thought to be efficiently scavenged by cloud droplets during convection. However, surprisingly high concentrations of ammonia and ammonium nitrate have recently been observed in the upper troposphere over the Asian monsoon region . Once particles have formed, co-condensation of ammonia and abundant nitric acid alone is sufficient to drive rapid growth to CCN sizes with only trace sulfate. Moreover, our measurements show that these CCN are also highly efficient ice nucleating particles-comparable to desert dust. Our model simulations confirm that ammonia is efficiently convected aloft during the Asian monsoon, driving rapid, multi-acid HNO -H SO -NH nucleation in the upper troposphere and producing ice nucleating particles that spread across the mid-latitude Northern Hemisphere.

Biogenic organic precursors play an important role in atmospheric new particle formation (NPF). One of the major precursor species is α-pinene, which upon oxidation can form a suite of products covering a wide range of volatilities. Highly oxygenated organic molecules (HOMs) comprise a fraction of the oxidation products formed. While it is known that HOMs contribute to secondary organic aerosol (SOA) formation, including NPF, they have not been well studied in newly formed particles due to their very low mass concentrations. Here we present gas- and particle-phase chemical composition data from experimental studies of α-pinene oxidation, including in the presence of isoprene, at temperatures (-50 and -30 .sup.\" C) and relative humidities (20 % and 60 %) relevant in the upper free troposphere. The measurements took place at the CERN Cosmics Leaving Outdoor Droplets (CLOUD) chamber. The particle chemical composition was analyzed by a thermal desorption differential mobility analyzer (TD-DMA) coupled to a nitrate chemical ionization-atmospheric pressure interface-time-of-flight (CI-APi-TOF) mass spectrometer. CI-APi-TOF was used for particle- and gas-phase measurements, applying the same ionization and detection scheme. Our measurements revealed the presence of C.sub.8-10 monomers and C.sub.18-20 dimers as the major compounds in the particles (diameter up to ⼠100 nm). Particularly, for the system with isoprene added, C.sub.5 (C.sub.5 H.sub.10 O.sub.5-7) and C.sub.15 compounds (C.sub.15 H.sub.24 O.sub.5-10) were detected. This observation is consistent with the previously observed formation of such compounds in the gas phase. However, although the C.sub.5 and C.sub.15 compounds do not easily nucleate, our measurements indicate that they can still contribute to the particle growth at free tropospheric conditions. For the experiments reported here, most likely isoprene oxidation products enhance the growth of particles larger than 15 nm. Additionally, we report on the nucleation rates measured at 1.7 nm (J.sub.1.7 nm) and compared with previous studies, we found lower J.sub.1.7 nm values, very likely due to the higher α-pinene and ozone mixing ratios used in the present study.