Aerosol Technique Research Articles

Evaluation of alginate-biopolymers (protein, hydrocolloid, starch) composite microgels prepared by the spray aerosol technique as a carrier for green tea polyphenols

Effects of low methoxyl pectin, milk protein concentrate (MPC), and waxy starch on the encapsulation of green tea-polyphenols in alginate gels produced using spray aerosol technique were evaluated. MPC and waxy starch treated first by cold-renneted induced gelation method and gelatinization method, respectively. DSC thermal analysis and FTIR spectroscopy were used to prove the presence of polyphenols in gel matrixes. The encapsulation efficiency (%EE) and the polyphenols release were investigated using Folin-Ciocalteu assay. The results showed that the addition of biopolymers into alginate gels increased the encapsulation efficiency (%EE) but reduced the release percentage of polyphenol in water and simulated gastric fluid (SGF). Among the three biopolymers, cold-renneted MPC gave the best protection for polyphenols encapsulated in alginate microgels. It increased %EE from 63% to 68% in fresh gels, reduced the release percentage in water from 72% to 62% and reduced the release percentage in SGF from 76% to 67%.

Optimising Aerosol Delivery for Maxillary Sinus Deposition in a Post-FESS Sinonasal Cavities

ABSTRACT Optimal management of chronic rhinosinusitis (CRS) endotypes includes post-operative application of topical formulations. There is little evidence regarding the ideal aerosol delivery characteristics and techniques to achieve the most efficient deposition on affected sinus mucosa. Nebulisers provide an alternative to nasal sprays by producing smaller particle sizes at lower velocities. We applied a reverse-particle-tracking simulation using computational fluid dynamics (CFD) to evaluate the ideal aerosol characteristics from a nebuliser to target the post-operative maxillary sinus mucosa. A CT scan of a CRS patient was used to create a pre-operative and virtual post-operative model. Particles of diameter 2 to 30 µm were tracked through the sinonasal cavity at 5, 10 and 15 L min–1 flow rates using CFD. Reverse particle simulations demonstrated that the optimised combination of parameters were 20 µm particles, delivered at 5 m s–1 (or 14 microns, delivered at 15 m s–1) at an inhalation rate of 5 L min–1, released from a nozzle in an elliptical oblique-superior direction into the superior half of the nasal valve significantly improved the maximum deposition efficiency (from 3% up to 55%) in the post-operative maxillary sinus mucosa. The nebulised spray (without optimisation) demonstrated negligible particle deposition within the sinuses of the pre-op model, while it increased marginally in the post-op model for smaller diameter particles at lower inhalation rates. The ideal combination of parameters to achieve targeted medication deposition on specific sinus mucosal surfaces can guide the development of new nasal drug delivery devices that produce the desired deposition regions for clinical applications in post-operative CRS patients.

Aerosolization and recovery of viable murine norovirus in an experimental setup

Noroviruses are the major cause for viral acute gastroenteritis in the world. Despite the existing infection prevention strategies in hospitals, the disease continues to spread and causes extensive and numerous outbreaks. Hence, there is a need to investigate the possibility of airborne transmission of norovirus. In this study, we developed an experimental setup for studies on the infectivity of aerosolized murine norovirus (MNV), a model for the human norovirus. Two aerosol generation principles were evaluated: bubble bursting, a common natural aerosolization mechanism, and nebulization, a common aerosolization technique in laboratory studies. The aerosolization setup was characterized by physical and viral dilution factors, generated aerosol particle size distributions, and the viral infectivity after aerosolization. We found a lower physical dilution factor when using the nebulization generator than with the bubble bursting generator. The viral dilution factor of the system was higher than the physical dilution; however, when comparing the physical and viral dilution factors, bubble bursting generation was more efficient. The infectivity per virus was similar using either generation principle, suggesting that the generation itself had a minor impact on MNV infectivity and that instead, the effect of drying in air could be a major reason for infectivity losses.

The ice-nucleating activity of Arctic sea surface microlayer samples and marine algal cultures

Abstract. In recent years, sea spray as well as the biological material it contains has received increased attention as a source of ice-nucleating particles (INPs). Such INPs may play a role in remote marine regions, where other sources of INPs are scarce or absent. In the Arctic, these INPs can influence water–ice partitioning in low-level clouds and thereby the cloud lifetime, with consequences for the surface energy budget, sea ice formation and melt, and climate. Marine aerosol is of a diverse nature, so identifying sources of INPs is challenging. One fraction of marine bioaerosol (phytoplankton and their exudates) has been a particular focus of marine INP research. In our study we attempt to address three main questions. Firstly, we compare the ice-nucleating ability of two common phytoplankton species with Arctic seawater microlayer samples using the same instrumentation to see if these phytoplankton species produce ice-nucleating material with sufficient activity to account for the ice nucleation observed in Arctic microlayer samples. We present the first measurements of the ice-nucleating ability of two predominant phytoplankton species: Melosira arctica, a common Arctic diatom species, and Skeletonema marinoi, a ubiquitous diatom species across oceans worldwide. To determine the potential effect of nutrient conditions and characteristics of the algal culture, such as the amount of organic carbon associated with algal cells, on the ice nucleation activity, Skeletonema marinoi was grown under different nutrient regimes. From comparison of the ice nucleation data of the algal cultures to those obtained from a range of sea surface microlayer (SML) samples obtained during three different field expeditions to the Arctic (ACCACIA, NETCARE, and ASCOS), we found that they were not as ice active as the investigated microlayer samples, although these diatoms do produce ice-nucleating material. Secondly, to improve our understanding of local Arctic marine sources as atmospheric INPs we applied two aerosolization techniques to analyse the ice-nucleating ability of aerosolized microlayer and algal samples. The aerosols were generated either by direct nebulization of the undiluted bulk solutions or by the addition of the samples to a sea spray simulation chamber filled with artificial seawater. The latter method generates aerosol particles using a plunging jet to mimic the process of oceanic wave breaking. We observed that the aerosols produced using this approach can be ice active, indicating that the ice-nucleating material in seawater can indeed transfer to the aerosol phase. Thirdly, we attempted to measure ice nucleation activity across the entire temperature range relevant for mixed-phase clouds using a suite of ice nucleation measurement techniques – an expansion cloud chamber, a continuous-flow diffusion chamber, and a cold stage. In order to compare the measurements made using the different instruments, we have normalized the data in relation to the mass of salt present in the nascent sea spray aerosol. At temperatures above 248 K some of the SML samples were very effective at nucleating ice, but there was substantial variability between the different samples. In contrast, there was much less variability between samples below 248 K. We discuss our results in the context of aerosol–cloud interactions in the Arctic with a focus on furthering our understanding of which INP types may be important in the Arctic atmosphere.

EJPD Impact Factor 2020: An extraordinary success!

The European Journal of Paediatric Dentistry (EJPD) has reached the extraordinary Impact Factor of 1.5 (Journal Citation Reports 2020 Release), passing in few years from 0.421 in 2015, when Luigi Paglia became Editor in Chief, taking over the Journal after Giuliano Falcolini. EJPD is the official journal of the Italian Society of Paediatric Dentistry (SIOI), but its scientific value and diffusion made it an authoritative reference source not only in Europe, but also worldwide. This is the result of the great work and commitment of the Editorial Board, composed by national and international experts, with the collaboration of the Managing Director Giuseppe Marzo and of the editorial staff. The prominent position that EJPD has gained in the international ranking of dental journals, where the top tier is dominated by those that mainly focus on adult patients, rewards its constant pursue of excellence of the scientific approach, giving at the same time great importance to articles dealing with everyday practice. This is the reason why the papers published in the EJPD are so rich in images. Communication through images is paramount for the current generation and generations to come. Digital diagnostic instruments and advanced treatments, 3D technologies, the current concepts of aerosol and no aerosol technique, together with the progress in the field of new dental materials, like bioactive cements for paediatric restorations or new biocompatible technopolymers (milled or 3D printed) for dentofacial orthopaedics and orthodontics are areas of great interest. We believe that our Journal should pay special attention to papers that take into account the overall health and wellness of the child using safe and efficient preventive, therapeutic or comfort techniques (laser, ozone, relative analgesia, caries diagnosis with transillumination, etc), also considering the importance of environmental conditions and promoting the collaboration with other specialists, with a focus on special need patients. EJPD also aims at guiding young paediatric dentists-graduating from postgraduate schools and residency programmes in paediatric dentistry-with a more comprehensive approach to the practical aspects of the profession, while striving to become the global scientific reference point of maternal and child oral care, defending them from the attractive flatteries of the predatory journals.

Transparent and Freestanding Single-Walled Carbon Nanotube Films Synthesized Directly and Continuously via a Blown Aerosol Technique.

Single-walled carbon nanotube (SWCNT) films are promising materials as flexible transparent conductive films (TCFs). Here, inspired by the extrusion blown plastic film technique and the SWCNT synthesis approach by floating catalyst chemical vapor deposition (FCCVD), a novel blown aerosol chemical vapor deposition (BACVD) method is reported to directly and continuously produce freestanding SWCNT TCFs at several hundred meters per hour. The synthesis mechanism, involving blowing a stable aerosol bubble and transforming the bubble into an aerogel, is investigated, and a general phase diagram is established for this method. For the SWCNT TCFs via BACVD, both carbon conversion efficiency and SWCNT TCF yield can reach three orders of magnitude higher than those with the conventional FCCVD. The film displays a sheet resistance of 40ohmsq-1 at 90% transmittance after being doped, representing the record performance based on large-scale SWCNT films. Transparent, flexible, and stretchable electrodes based on BACVD films are demonstrated. Moreover, this high-throughput method of producing SWCNT TCFs can be compatible with the roll-to-roll process for mass production of flexible displays, touch screens, solar cells, and solid-state lighting, and is expected to have a broad and long-term impact on many fields from consumer electronics to energy conversion and generation.

Therapeutic Aerosol: Thermodynamic Method for Managing the Aerosol Particle Size

The inhalation therapy delivers the drugs to the sites and helps to release a respiratory route. The aerosol therapy results highly depend on the depth of drug penetration into the respiratory system, which is primarily determined by the optimal size of the aerosol particles, the farther their penetration is required, the smaller their size should be. In clinical practice, various modes are used to generate the desired particle size. As a result, the drug particles in a certain size are obtained for a more accurate delivery system. However, such different methods for changing the size of drug particles do not provide satisfactory results. Also, the applied pressure in the aerosol technique allows traveling the drug particles at a rapid-uncontrolled speed, causing impaction in the respiratory route. The aerosol is unstable and changes its state under different circumstances, such as the influence of gravity, coagulation, and others. Conventional aerosol nebulizer does not have the privileges, similar to that in the aerosols that used dry powder inhaler or colloidal solutions, which would interfere with the adhesion of particles. In this paper, the authors developed a mathematical approach based on using hot pressurized airflow to control particle size, also determine the speed and the entire time of droplet (drug particles) evaporation. As a result, it can be managed the decreasing of the larger particle sizes and guarantee more deposition of drugs. The proposed method prevents particles from adhering to each other and delivering the best percentage of the drug to the lungs.

Establishing a pattern in the influence of two-layer greasing on the wear resistance of rails

This paper reports the results of an experimental study into the influence of two-layer greasing, formed from the graphite powder and base molecules of industrial oil, on the durability of the side surface of a rail head. Thus, increasing the concentration of graphite powder in oil from 0 to 3 % under a load of 363‒646 N decreases a wear rate by 42‒29.7 %, respectively. The study procedure implied modeling the process of rolling friction at slippage using rollers at the SMC-2 friction machine. This particular type of friction occurs in the tribosystem wheel flange the side surface of a rail head in the curved track sections. The supply of oil applying an aerosol technique was also implied. Two independent factors were varied: the concentration of graphite powder in the industrial oil I-12A and an external load. The constant factors were the roller rotation frequency, which enabled stable slippage at the level of 20 %, and oil temperature, and the duration of each test. The results of the experiment have made it possible to derive a regression equation, which describes the wear pattern of a roller in the friction pair «roller‒roller» depending on the selected factors. At the final stage of this work, we calculated a rail resource in the curved track section. The results of calculating a railroad rail resource under conditions of increasing the concentration of graphite powder from 0 to 3 % at external loads from 363 to 646 N have demonstrated an increase in the rail resource from 40 to 61 %. The calculation was based on the obtained experimental data, which characterize the friction process between the side surface of a rail head and the wheel flange in a curved track section under the conditions of two-layer greasing at various loads. The two-layer greasing was formed through the aerosol application of oil onto the friction surface with a different concentration of graphite. The data obtained make it possible to predict the service life of rails in the curved track sections under conditions of two-layer greasing

The Effect of the Comparison of Sodium Alginate-Gelatin Levels on Microspheres Characteristics (Produced by Ionic Gelation Method Aerosolized Technique)

The aim of this research is to investigate the effect of concentration ratio of sodium alginate-gelatin on the characteristics of microspheres. Microspheres were prepared with ionotropic gelation methods aerosolization technique with sodium alginate and gelatin as polymer matrixes, and calcium chloride (1.5 M) as the cross-linker, and then dried using freeze dryer. The concentration ratio of sodium alginate-gelatin that was used to make microsphere was divided into F1: 2.25:0.25%, F2: 1.75:0.75%, and F3: 1.25:1.25%. Resulting microspheres were characterized in terms of characteristics (yield, particle size, and swelling index). The result showed that there was an increase in yield and particle size, as sodium alginate concentration increased on formula. The statistical test showed the concentration ratio of sodium alginate-gelatine showed a significant meaning different from the yield and particle size. The swelling index shows that the swelling peak of microspheres became more quickly with increased sodium alginate concentration.

Effects of Aerosol Insecticide Application Location on the Patterns of Residual Efficacy Against Tribolium confusum (Coleoptera: Tenebrionidae) Larvae.

Aerosol insecticides are one tool that pest management professionals can utilize as a spatial treatment inside food facilities and storage warehouses. Methods of aerosol application can vary significantly and can affect the spatial pattern of efficacy achieved. We investigated how the location from which an aerosol insecticide is applied inside a mill influenced the spatial dispersal of the insecticide. Treatments were performed using two commercial formulations, pyrethrin + pyriproxyfen (insect growth regulator [IGR]) and pyrethrin + methoprene (IGR), applied at one of three static locations or a fourth application comprising of splitting the application among all three locations. Concrete arenas were placed out at different locations within the mill during applications. At 2, 4, and 6 wk post-aerosol application, Tribolium confusum Jacquelin du Val, confused flour beetle, larvae were added to the concrete arenas and monitored for development and efficacy was evaluated based on percent adult emergence and an efficacy index that ranged from 1 (low) to 21 (high). The spatial pattern of aerosol coverage varied between insecticide formulations and the aerosol application location. Areas of the mill near walls, corners, equipment, and farthest away from the application location had larger zones of low efficacy index values among all four application locations. This study illustrated that the aerosol insecticide formulation, application location, and delivery method all significantly influenced residual efficacies of the insecticides. To increase the overall spatial coverage and IGR efficacy, targeting these areas of a mill floor with the aerosol or additional intervention techniques would increase uniform coverages and overall effectiveness.

Effect of CaCl 2 Crosslink Solution Concentration on the Characteristics of Gelatin Alginate Microspheres

Alginate as a constituent of microspheres matrix has a weakness, namely the lack of ability to slow the release of drugs from the system, causing the effects of drug therapy to the body to be less than optimal. To obtain preparations with slowed release, sodium alginate needs to be combined with other polymers such as gelatin. This study aims to determine the effect of the concentration of CaCl 2 connection solution on the characteristics of alginate-gelatin microspheres. In this study, alginate-gelatin microspheres were prepared using ionotropic gelation aerosolization techniques. Three formulas were made, each of which was replicated three times. F1 with CaCl concentration2 0.5 M, F2 with CaCl concentration2 1.0 M, F3 with a concentration of 1.5 M. The three formulas were made in the ratio of alginate-gelatin (1.5: 1)% and a crosslinking time of 1.5 hours. Evaluation of the characteristics of microspheres includes yield percentage, organoleptic, moisture content, morphology of microspheres, size and size distribution of microspheres, and swelling index. The data of this study were analyzed using one way ANNOVA. The results reveals a loss of specific uptake of the COO-manuronate alginate group and the occurrence of wave number shifts as well as an increase in the absorption intensity of the C = O group. Organoleptic examination results of alginate-gelatinin microspheres showed that microspheres of the three formulas had the same organoleptic, and formed spherical microspheres. On the inspection of swelling index, it was found that F1 and F2 reached the peak of swelling at 2 o’clock, while F3 reaches the peak of swelling at 3 o’clock. The greater the level of CaCl2, then the average diameter of microspheres will also increase, while the swelling index will decrease with increasing levels of CaCl2. In the results of moisture content examination, there is no difference in different CaCl 2.

Optimization Performance and Physical Stability of Ciprofloxacin HCL-Ca Alginate Microspheres: Effect of Different Concentration of Alginate and CaCl2

Inhalation treatment using antibiotics is an alternative for lung delivery. However, the therapeutic efficacy of inhaled drugs is limited by their rapid clearance in the lungs. Sustained release systems in the lungs can improve therapeutic outcomes of drugs because they can retain the drug load within the lungs and progressively release the drug locally at therapeutic levels. This study presents the formulation strategies to control drug release in the lungs using an alginate polymer-based microspheres system. The microsphere’s composition can be adjusted to modulate release and can encapsulate compounds with high loading. The pulmonary route is commonly used and has been well accepted as a portal for non-invasive drug delivery for many lung diseases. It is explored for decades as an alternative for systemic as well as local drug delivery. The present study explored the in vitro benefits of ciprofloxacin encapsulated in alginate microspheres. The studies included size, morphology, yield, drug loading, and encapsulation efficiency as well as stability. Current results showed small, smooth, and spherical ciprofloxacin-alginate microspheres were produced using aerosolization techniques. Small particles of less than 5μm were formed, which suitable for inhalation particles for lung delivery. High entrapment efficiency up to 95%, loadings of 80%, and a yield of 89% were also showed from microspheres. It was confirmed that all microspheres were stably indicated by no significant changes in morphology, organoleptic, and drug content after 30 days of storage. The recent promising characteristics of microspheres for pulmonary delivery will need further evaluation of the potency against microorganisms in lung disease.

Aerosol Synthesis of High Entropy Alloy Nanoparticles.

Homogeneously mixing multiple metal elements within a single particle may offer new material property functionalities. High entropy alloys (HEAs), nominally defined as structures containing five or more well-mixed metal elements, are being explored at the nanoscale, but the scale-up to enable their industrial application is an extremely challenging problem. Here, we report an aerosol droplet-mediated technique toward scalable synthesis of HEA nanoparticles with atomic-level mixing of immiscible metal elements. An aqueous solution of metal salts is nebulized to generate ∼1 μm aerosol droplets, which when subjected to fast heating/quenching result in decomposition of the precursors and freezing-in of the zero-valent metal atoms. Atomic-level resolution scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis reveals that all metal elements in the nanoparticles are homogeneously mixed at the atomic level. We believe that this approach offers a facile and flexible aerosol droplet-mediated synthesis technique that will ultimately enable bulk processing starting from a particulate HEA.

Continuous 2000 K droplet-to-particle synthesis

Aerosol spray coupled with high-temperature pyrolysis is an emerging technique for continuous manufacturing of nanomaterials at large scale that demonstrates extremely high production efficiency. Current aerosol spray techniques using a tube furnace can only attain a low temperature range (generally <1500 K), rendering limited products as well as inhomogeneous heating within the comparatively bulky furnace chamber (typical dimensions of ≥2 cm in diameter and ≥40 cm in length), which leads to difficulties in product quality control. Here we report a “droplet-to-particle” aerosol technique coupled with a high-temperature (∼2000 K) micro-channel reactor, which provides ∼100-times smaller dimensions compared to conventional tube furnaces, enabling homogeneous and high-temperature nanomaterial manufacturing. To demonstrate the unique capability of this carbonized wood micro-channel reactor, we successfully synthesized multielement high entropy alloy/oxide nanoparticles (which typically require a high temperature (2000 K) to achieve uniform elemental mixing) in a continuous and support-free manner. Droplets atomized from the multielement precursors fly through the micro-channels heated to 2000 K by Joule heating with a residence time of only tens of milliseconds with a high energy conversion efficiency (>95%), during which salt decomposition and particle nucleation/growth occur. The high temperature critically enables homogeneous mixing of elements in the resultant nanoparticles and the short residence time is key to suppress particle growth and agglomeration. Compared with the traditional aerosol spray pyrolysis, the carbonized wood reactor can achieve a record high temperature (≥2000 K), a much shorter residence time (∼tens of milliseconds), highly efficient, uniform heating, and provide a platform for continuous nanomaterial manufacturing for a broad range of applications.

Characterization of microspheres in alginate-gelatin matrix with ionotropic gelation method and aerosolization technique

Characterization of microspheres in alginate-gelatin matrix with ionotropic gelation method and aerosolization technique

Physical Characteristics of Erythropoetin Encapsulated into Alginate Polymer Using Aerosolization Technique

The aim of this research was to evaluate physical characteristics of erythropoietin encapsulated into alginate polymer using a microparticle technology called aerosolization technique at different polymer concentrations. Erythropoetin is a model of neuroprotectant drugs. The sodium alginate concentrations used were 1%, 2%, and 3% with 1M cross-linker CaCl2. The physical characteristics in terms of morphology, particle size, swelling index, yield, and structural integrity of erythropoietin-Ca alginate microspheres were determined. Microsphere evaluation included FT-IR, DTA, moisture content, morphology using SEM, particle size distribution using optical microscopy, determination of swelling index, and yield. SDS PAGE electrophoresis was also conducted to evaluate the molecular weight of erythropoietin before and after the microencapsulation process.The resulting microspheres had spherical form, smooth surface, and the sizes below 5 μm. The determination of swelling index was performed using two methods, namely calculation of mass differentiation and size differentiation at 24 and 30 hours. Results of examination from swelling indices in F1, F2, F3 were 0.58, 1.25, 1.43 (at 24 hours) and 0.78, 1.78, 2.16 (at 30 hours), respectively, whereas resulted of swelling index of 0.50, 1.15, 1.32 (by size method at 24 hours), and 0.65, 1.80, 1.98 (at 30 hours). The result of yield microspheres of F1, F2, F3 were 75.55% ± 0, 350; 77, 84% ± 0, 290; and 86, 65% ± 0, 191. Statistical result showed that an increase of alginate concentration causes an increse in particle size, swelling indeks, and yield. From SDS PAGE profile, it was confirmed that erythropoietin maintains its structural integrity evidenced by the similar molecular weight before and after encapsulation process. This study has demonstrated the potential of erythropoietin-alginate microspheres that may be effective as a neuroprotectant drug.

Characteristics And Release Of Gentamicin Sulphate From Sodium Alginate Microspheres Entrapped In Emulgel

Gentamicin sulfate is a broad-spectrum aminoglycoside antibiotic that can be used for primary and secondary infections of the skin. Microspheres can be used to extend drug release on the skin; the resulting therapeutic effect is constant and has a longer duration of action. Therefore it can reduce the frequency of use and increase patient compliance. This study investigated the appropriate profile and release kinetics model of gentamicin sulfate microspheres entrapped on the emulgel base. Gentamicin-alginate microspheres were made by the ionotropic gelation method with aerosolization technique, using 2.5% Na-alginate low viscosity, CaCl2 solution of 1.5M as a crosslinker, maltodextrin as lyoprotectant and were dried using the freeze-drying method. The result of microspheres characterization, gentamicin microsphere was spherical with smooth surface structure and had particle diameter of 3.021 ± 0.017μm. Gentamicin microspheres had moisture content 2.89%, and maximum swelling index was 2625 ± 21.70% was achieved within 5 hours. The drug loading of microspheres was 1.75 ± 0.11%, and entrapment efficiency was 10.96 ± 0.19%. The release evaluation during 720 minutes showed that the amount of gentamicin release from alginate microspheres on emulgel base was 14.857 ± 0.816%, and gentamicin release on emulgel conventional was 49.239 ± 5.954%. The model of release kinetics of gentamicin microspheres on emulgel was Higuchi model that showed the release of the active ingredient through the diffusion process. While the model of release kinetics of gentamicin on emulgel base was first order, that showed the release of active agent depends on remaining concentration.

Working with Minions: Assisted Scalable Bio-nanomanufacturing of Functional Materials

The fictional “Minions” from film are single-focused workers, useful for accomplishing a specific task en masse. Here, minion-like bacteria is presented as a useful intermediary craftsman for functionalizing biomaterials, enabling a generic process for integrating desired chemical additives and/or nanoparticles.

Enrichment of organic nitrogen in primary biological particles during advection over the North Atlantic

Using a number of datasets from single particle Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS) measurements, we show only a minor presence of Organic Nitrogen (ON) species in Saharan dust particles (aerosol size range 0.2–3 μm) collected at their origin. ON enhancement is not observed on Saharan dust particles after atmospheric transport (48–96 h) either over the Tropical Ocean in the vicinity of Cape Verde, over the North Atlantic Ocean. In the negative ATOFMS mass spectra, signals due to ON species were found weaks in biological particles (rich in potassium and phosphate) in their source area, and signals due to alkylamines in the positive ATOFMS mass spectra were not found. In striking contrast, biological particles travelling within aerosol dust plumes are found to be enriched in ON species - including alkylamines - in North Atlantic Ocean air (Mace Head, Ireland), as seen in both positive and negative ATOFMS mass spectra. Contrary to filter based aerosol techniques which report ON enrichment within Saharan dust, our single particle mass spectrometry data - allowing study of the aerosol mixing state - suggests that the aging biological particles and not the associated transported aging Saharan dust may be a source of ON species. We suggest biogeochemical processes occurring in the atmosphere in which biological particles are responsible for ON production. This may be an important source of nutrients to the ocean via atmospheric deposition.

57Fe Mössbauer study of high-yield CuFe2O4 nanoparticles produced by the levitation-jet aerosol technique with post-synthesis annealing

Pseudo-spherical cubic-shaped nanoparticles of spinel ferrite CuFe2O4 have been prepared using a two-stage process. At first, an evaporation of levitating copper–iron drop into mix of helium–air gas flow took place, which resulting in copper ferrite-based powders. Then, such powders were additionally oxidized trough the heterogeneous auto-wave combustion in open air. We studied the effect of performing the synthesis in either an air or a helium environment on the phase composition of nanoparticles, and how the use of a post-synthesis annealing step modifies this, using room temperature 57Fe Mossbauer spectroscopy. By applying this technique, we are able to distinguish between the normal (non-magnetic) and inverse cubic (magnetic) phases of CuFe2O4, which is usually inaccessible using X-ray diffraction, as well as quantifying their relative amounts within each sample. Furthermore, we have been able to quantify trace amounts of the tetragonal CuFe2O4, phases that are typically obscured by line-broadening effects within our X-ray diffraction data, which indicates that annealing using a propane flame can also cause a cubic to tetragonal distortion in the crystal structure of the spinel lattice. Finally, by combining our Mossbauer parameters, which are sensitive to the Fe-containing phases only, with X-ray diffraction data, which are sensitive to all phases, we report on the full phase composition for the first time for nanoparticles produced via this synthesis route.