Sea spray aerosol concentration modulated by sea surface temperature

Mucus Transpiration as the Basis for Chronic Cough and Cough Hypersensitivity

Chronic cough is characterized by a state of cough hypersensitivity. We analyze the process of transpiration, by which water appears to evaporate from laryngeal and tracheal mucus as from the surface of a leaf, as a potential cause of cough hypersensitivity. In this process, osmotic pressure differences form across mucus, pulling water toward the air, and preventing mucus dehydration. Recent research suggests that these osmotic differences grow on encounter with dry and dirty air, amplifying pressure on upper airway epithelia and initiating a cascade of biophysical events that potentially elevate levels of ATP, promote inflammation and acidity, threaten water condensation, and diminish mucus water permeability. Among consequences of this inflammatory cascade is tendency to cough. Studies of isotonic, hypotonic, and hypertonic aerosols targeted to the upper airways give insights to the nature of mucus transpiration and its relationship to a water layer that forms by condensation in the upper airways on exhalation. They also suggest that, while hypertonic NaCl and mannitol may provoke cough and bronchoconstriction, hypertonic salts with permeating anions and non-permeating cations may relieve these same upper respiratory dysfunctions. Understanding of mucus transpiration and its role in cough hypersensitivity can lead to new treatment modalities for chronic cough and other airway dysfunctions promoted by the breathing of dry and dirty air.

Sea Salt Aerosol Identification Based on Multispectral Optical Properties and Its Impact on Radiative Forcing over the Ocean

The ground-based measurement of sea salt (SS) aerosol over the ocean requires the massive utilization of satellite-derived aerosol products. In this study, n-order spectral derivatives of aerosol optical depth (AOD) based on wavelength were examined to characterize SS and other aerosol types in terms of their spectral dependence related to their optical properties such as particle size distributions and complex refractive indices. Based on theoretical simulations from the second simulation of a satellite signal in the solar spectrum (6S) model, AOD spectral derivatives of SS were characterized along with other major types including mineral dust (DS), biomass burning (BB), and anthropogenic pollutants (APs). The approach (normalized derivative aerosol index, NDAI) of partitioning aerosol types with intrinsic values of particle size distribution and complex refractive index from normalized first- and second-order derivatives was applied to the datasets from a moderate resolution imaging spectroradiometer (MODIS) as well as by the ground-based aerosol robotic network (AERONET). The results after implementation from multiple sources of data indicated that the proposed approach could be highly effective for identifying and segregating abundant SS from DS, BB, and AP, across an ocean. Consequently, each aerosol’s shortwave radiative forcing and its efficiency could be further estimated in order to predict its impact on the climate.

Sea spray aerosols intervening phospholipids ozonolysis at the air-water interface

With more than half of the world's population lives along the coast and in its vicinity, the sea spray aerosols (SSAs) with respect to respiratory system impact has attracted increasing attention. In this paper, ozonolysis of model lung phospholipids intervened by salt cations in SSAs at air-water interface was investigated using acoustic levitation-nano-electrospray ionization-mass spectrometry (AL-nano-ESI-MS). The cation species facilitated the interfacial ozonolysis of phospholipids, and this increased ozonolysis showed a dependence on the concentration of salt cations. The charge number and ion radius of salt cations were also investigated, and the times of increased efficiency for phospholipids ozonolysis at the air-water interface were higher with more charge numbers or lower ion radius. The mechanism study revealed that the electrostatic interaction between the electronegative headgroup of phospholipids and the cations disturbed the packing of phospholipids, and resulted in oleyl chains more vulnerable with ozone. Finally, aerosolization of the salt-dominated artificial seawater and real seawater revealed a significant increase on ozonolysis of phospholipid intervened by salt cations. These results reveal SSAs intervening phospholipids interfacial reaction at the molecule level, which will be beneficial to gain the knowledge of the negative health effect concerning the components involved in SSAs.

Diel cycle of sea spray aerosol concentration

Sea spray aerosol (SSA) formation have a major role in the climate system, but measurements at a global-scale of this micro-scale process are highly challenging. We measured high-resolution temporal patterns of SSA number concentration over the Atlantic Ocean, Caribbean Sea, and the Pacific Ocean covering over 42,000 km. We discovered a ubiquitous 24-hour rhythm to the SSA number concentration, with concentrations increasing after sunrise, remaining higher during the day, and returning to predawn values after sunset. The presence of dominating continental aerosol transport can mask the SSA cycle. We did not find significant links between the diel cycle of SSA number concentration and diel variations of surface winds, atmospheric physical properties, radiation, pollution, nor oceanic physical properties. However, the daily mean sea surface temperature positively correlated with the magnitude of the day-to-nighttime increase in SSA concentration. Parallel diel patterns in particle sizes were also detected in near-surface waters attributed to variations in the size of particles smaller than ~1 µm. These variations may point to microbial day-to-night modulation of bubble-bursting dynamics as a possible cause of the SSA cycle.

Sea spray aerosol (SSA) are an important way through which oceans can influence the atmosphere’s radiative properties. Here, the authors present measurements taken over a 42,000 km ship cruise in the Atlantic and Pacific Ocean and show that SSA number concentrations vary over a 24-hour cycle, possibly linked to surface water bubble-bursting dynamics.

Inhaled Water and Salt Suppress Respiratory Droplet Generation and COVID-19 Incidence and Death on US Coastlines

Dry air alters salt and water balance in the upper airways and increases the risks of COVID-19 among other respiratory diseases. We explored whether such upper airway variations in salt and water balance might alter respiratory droplet generation and potentially contribute to observed impacts of airway hydration on respiratory disease. In a randomized 4-arm study of 21 healthy human subjects we found that the breathing of humid air, the wearing of cotton masks, and the delivery of (sodium, calcium, and magnesium chloride) salt droplets sized to deposit in the nose, trachea, and main bronchi similarly reduce the exhalation of respiratory droplets by approximately 50% ([Formula: see text] < 0.05) within 10 minutes following hydration. Respiratory droplet generation returns to relatively high baseline levels within 60–90 minutes on return to dry air in all cases other than on exposure to divalent (calcium and magnesium) salts, where suppression continues for 4–5 hours. We also found via a preliminary ecological regression analysis of COVID-19 cases in the United States between January 2020 and March 2021 that exposure to elevated airborne salt on (Gulf and Pacific) US coastlines appears to suppress by approximately 25%–30% ([Formula: see text] < 0.05) COVID-19 incidence and deaths per capita relative to inland counties — accounting for ten potential confounding environmental, physiological, and behavioral variables including humidity. We conclude that the hydration of the upper airways by exposure to humidity, the wearing of masks, or the breathing of airborne salts that deposit in the upper airways diminish respiratory droplet generation and may reduce the risks of COVID-19 incidence and symptoms.

A Molecular Pinball Machine of the Plasma Membrane Regulates Plant Growth-A New Paradigm

Novel molecular pinball machines of the plasma membrane control cytosolic Ca²⁺ levels that regulate plant metabolism. The essential components involve: 1. an auxin-activated proton pump; 2. arabinogalactan glycoproteins (AGPs); 3. Ca²⁺ channels; 4. auxin-efflux "PIN" proteins. Typical pinball machines release pinballs that trigger various sound and visual effects. However, in plants, "proton pinballs" eject Ca²⁺ bound by paired glucuronic acid residues of numerous glycomodules in periplasmic AGP-Ca²⁺. Freed Ca²⁺ ions flow down the electrostatic gradient through open Ca²⁺ channels into the cytosol, thus activating numerous Ca²⁺-dependent activities. Clearly, cytosolic Ca²⁺ levels depend on the activity of the proton pump, the state of Ca²⁺ channels and the size of the periplasmic AGP-Ca²⁺ capacitor; proton pump activation is a major regulatory focal point tightly controlled by the supply of auxin. Auxin efflux carriers conveniently known as "PIN" proteins (null mutants are pin-shaped) pump auxin from cell to cell. Mechanosensitive Ca²⁺ channels and their activation by reactive oxygen species (ROS) are yet another factor regulating cytosolic Ca²⁺. Cell expansion also triggers proton pump/pinball activity by the mechanotransduction of wall stress via Hechtian adhesion, thus forming a Hechtian oscillator that underlies cycles of wall plasticity and oscillatory growth. Finally, the Ca²⁺ homeostasis of plants depends on cell surface external storage as a source of dynamic Ca²⁺, unlike the internal ER storage source of animals, where the added regulatory complexities ranging from vitamin D to parathormone contrast with the elegant simplicity of plant life. This paper summarizes a sixty-year Odyssey.