Spray Source Research Articles

Effect of Boron, Potassium Sources and Rates on Soil Fertility, Sugar Beet Yield and Quality Cultivated in Saline Clay Soil in Egypt

Two field experiments were conducted at a private farm in El-QantaraSharq, Ismailia Governorate, Egypt, during the 2021/22 and 2022/23 winter growing seasons. The study aimed to assess the effect of boron and potassium sources and rates on sugar beet yield quality and soil fertility. The experiments were arranged in a split-split plot design. The main plots had foliar boron (B) application (without and with 4 g B/L), while the sub-main plots had potassium sources: K-sulfate, K-silicate, and K-humate. The sub-plots had potassium rates (0, 4, 8, and 12 g/L) applied as foliar spray at three intervals: 30, 45, and 75 days after planting. Results indicated that foliar boron application led to a 17.17% decrease in soil electrical conductivity (EC) compared to without boron spraying. However, there was no significant change in pH values. The study showed a significant increase in soil available N, P, K, Fe, Mn, Zn, and B with the application of 4 g/L of boron or K-humate at a rate of 12 g/L individually. Sugar beet yield, quality and root nutrients content were notably influenced by potassium sources in the following order: K-humate > K-silicate > K-sulfate. The interaction between boron spray and potassium sources and rates had a significant effect on various parameters, with the highest values for root length (cm), fresh root weight (kg/plant), root and top yield (t/ha), protein (%),sugar content (%) and sugar yield (t/ha) achieved by foliar application of boron combined with K-humate at a rate of 12 g/L.

Overview of Malaria in Pregnancy: Challenges and Strategies for Effective Prevention

Malaria in pregnancy is a significant public health issue in sub-Saharan Africa, with 30 million pregnancies at risk each year. Pregnant women are particularly vulnerable due to immunological changes and the placental environment that facilitates parasite sequestration. The predominant malaria parasite, Plasmodium falciparum, is associated with significant maternal and fetal complications. Effective malaria prevention strategies include insecticide-treated nets (ITNs) and intermittent preventive treatment (IPTp) with Sulfadoxine-pyrimethamine. However, adherence to preventive chemotherapy is challenging due to side effects and socioeconomic barriers. Health education programs are crucial for increasing awareness and promoting preventive behaviors. Early diagnosis and prompt treatment are critical for managing severe malaria cases. Environmental and vector control measures, such as indoor residual spraying and larval source management, are vital for reducing mosquito populations and transmission. Nutritional interventions support immune function and overall health. Access to healthcare services, innovative technologies, and cultural and socioeconomic factors are essential for overcoming barriers to malaria prevention and treatment. Continuous monitoring and evaluation are crucial for refining interventions and improving health outcomes. Keywords: Malaria, Pregnancy, Challenges, Strategies, Effective Prevention

Water Microdroplets in Air: A Hitherto Unnoticed Natural Source of Nitrogen Oxides.

Water microdroplets are widespread in the atmosphere. We report a striking observation that micron-sized water droplets obtained from zero-volt spray sources (sonic spray, humidifier, spray bottle, steamer, etc.) spontaneously generate nitrogen oxides. The mechanistic investigation through the development of custom-designed sampling sources combined with mass spectrometry and isotope labeling experiments confirmed that air nitrogen reacts with the water at the air-water interface, fixing molecular nitrogen to its oxides (NO, NO2, and N2O) and acids (HNO2 and HNO3) at trace levels without any catalyst. These reactions are attributed to the consequence of an experimentally detected feeble corona discharge (breakdown of air) at the air-water interface, likely driven by the high intrinsic electric field at the surface of water microdroplets. The extent of this corona discharge effect varies depending on the pH, salinity/impurity, size, speed, and lifetime of microdroplets in the air. Thus, this study discloses that the air-water interface of microdroplets breaks the strong chemical bond of nitrogen (N2), producing nitrogen oxides in the environment, while lightning strikes and microbial processes in soil are considered their dominant natural sources. As nitrogen oxides are toxic air pollutants, their spontaneous formation at the air-water interface should have important implications in atmospheric reactions, requiring further investigations.

Cost effectiveness of malaria vector control activities in Sudan

BackgroundMalaria vector control activities in Sudan rely largely on Long-Lasting Insecticidal Nets (LLINs), Indoor Residual Spray (IRS) and Larval Source Management (LSM). The present study attempted to determine cost effectiveness of inputs and operations of vector control interventions applied in different environmental settings in central and eastern Sudan, as well as their impact.MethodsThe inputs utilized and cost of each vector control activity, operational achievements and impact of the applied malaria vector control activities; IRS, LLINs and LSM were determined for eight sites in Al Gazira state (central Sudan) and Al Gadarif state (eastern Sudan). Operational costs were obtained from data of the National Malaria Control Program in 2017. Impact was measured using entomological indicators for Anopheles mosquitoes.ResultsThe total cost per person per year was $1.6, $0.85, and $0.32 for IRS, LLINs and LSM, respectively. Coverage of vector control operations was 97%, 95.2% and 25–50% in IRS, LLINs and LSM, respectively. Vectorial capacity of malaria vectors showed statistically significant variations (P < 0.034) and ranged 0.294–0.65 in areas implemented LSM in comparison to 0.097–0.248 in areas applied IRS and LLINs, respectively. Both indoor and outdoor biting Anopheles mosquitoes showed noticeable increase that reached 3–12 folds in areas implemented LSM in comparison to areas implemented IRS and LLINs. Annual malaria prevalence was 13.1–21.1% in areas implemented LSM in comparison to 3.20%, 4.77% in areas implemented IRS and LLINs, respectively.ConclusionIRS and LLINs are cost effective control measures due to adequate inputs and organized process. However, the unit cost of LSM intervention per outcome and subsequently the impact is hugely affected by the low coverage. The very weak support for implementation of LSM which includes inputs resulted in weakness of its process and consequently its impact. Implementation of LSM by local government in urban settings is challenged by many factors the most important are maintenance of adequate stable level of funding, un-adequate number of well trained health workers, unstable political and administrative conditions and weak infrastructure. These challenges are critical for proper implementation of LSM and control of malaria in urban settings in Sudan.

Dancing ejecta

Splashing of impacting drops produces a myriad of secondary spray droplets, which generate aerosols during rain on the ocean and can cause health hazards during the spraying of pesticides or enhance the droplet transmission of disease. Determining the size and number of the finest splashed droplets is therefore of practical interest. Herein, we use a novel experimental facility with a 26 m tall vacuum tube, to study well-controlled drop impacts at velocities as high as 22 m s $^{-1}$ , where we reach parameter regimes not studied before using freely falling drops. Using extreme video frame rates, we pinpoint the primary source of the finest spray, coming from the catastrophic bending and rupture of the sub-micron-thick ejecta sheet, which emerges at a high speed from the neck connecting the drop and pool. The axisymmetric bending and convoluted ejecta shapes are driven primarily by resistance from the surrounding air, but also depend on the viscosity difference between drop and pool, which influences the initial ejection angle of the sheet. These extreme impact conditions provide new insights into general spray formation, through a sequence of bucklings of the rising ejecta, which dances next to the drop surface and can also form an enclosed air torus.

On the use of flamelet model approach in analyzing the mixing-controlled spray flame dynamics

This research examines the application of unsteady flamelet modeling to consider the impact of turbulent-chemistry interaction (TCI) on a mixing-controlled spray flame. The model incorporates the Representative Interactive Flamelets (RIF) approach to represent the sub-grid scaled heterogeneous mixture along with chemical reactions. This is combined with an Eulerian Particle Flamelet Model (EPFM), which uses multiple flamelets to account for the history of unsteady flames. The results are compared with those of a first-order moment method known as the Well-Stirred Reactor (WSR) model. The numerical simulations were carried out using a Reynolds Averaged Navier–Stokes (RANS) solver incorporated in two different CFD platforms, a commercially available CFD code, CONVERGE, and C++ based open-source CFD code, OpenFOAM. The test conditions were employed based on the Engine Combustion Network (ECN) Spray-A setup. The simulation results obtained interchangeably using both CFD software are investigated to address essential aspects of the RIF model. In order to ensure accurate predictions in the mixing field, adjustments were made to the original OpenFOAM code to enhance the treatment of time-stepping for spray source terms. This refinement allows for an adequate resolution of spray-induced mixing. While there are slight variations in the implementation of the RIF model between OpenFOAM and CONVERGE, both CFD codes effectively reproduce the physics of mixing-controlled combustion. This includes accurately representing important phenomena like mixing-controlled turbulent spray flame and combustion recession.

Numerical simulation study of indoor disinfection spray distribution based on CFD-DPM method

In today's world, environmental safety has become a top priority, with a special focus on terminal disinfection of indoor environments, which has proven to be a crucial and formidable issue in infection control. The use of hydrogen peroxide disinfection through vaporization or atomization presents a viable solution to the challenges posed by traditional wiping disinfection and ultraviolet disinfection methods that are plagued by incomplete disinfection and other factors that can significantly reduce the virus content within a room. To improve the application of hydrogen peroxide disinfection spray, the CFD-DPM (Computational Fluid Dynamics-Discrete Particle Model) method is employed to simulate the particle distribution of traditional sprays in a 30 m3 room. The study places emphasis on analyzing the impact of the placement position and bottle number of disinfection spray on the distribution of spray particles. The results demonstrate an impressive consistency between the numerical simulation method and experimental findings regarding the particle size distribution of disinfectant spray across various Schemes, validating the method's accuracy and reliability. However, the placement of a single disinfection spray source is insufficient to achieve uniformly distributed particles throughout the space when a bathroom is present within a given room. Nevertheless, by placing internal and external sources within the bathroom, the distribution of disinfectant spray particles becomes more even, thanks to a well conceived placement technique and an increased number of spray sources. Among all the schemes tested, Scheme 4 stands out for its ability to produce the greatest number of spray particles, with almost 60.71% of these particles remaining airborne for over 40 s. Therefore, it is also the most effective scheme for conducting disinfection.

Parameterizations for sea spray aerosol production flux

Sea spray aerosols (SSA) are important contributors to the global aerosol load, and they have a significant impact on the global climate system and chemical processes. To better assess the environmental impact of SSA emissions, it is important to quantitatively characterize the parametric dependence of SSA production fluxes on other environmental variables, and assess their role in global climate models (GCMs) and chemical transport models (CTMs). There are currently significant differences in the simulation of global SSA production fluxes in various models, and these differences are mainly attributed to the differences in the sea spray source functions (SSSFs). Research in the literature over the last decade has greatly broadened the knowledge of SSSFs and improved our understanding of SSA production fluxes and how they are applied in models. This paper clarifies the derivation process of different SSSFs, and provides a critical review of the application progress of different SSSFs in different models, which plays an important role in improving the accuracy of model simulations to evaluate the impact of SSA. More specifically, we review the studies related to the parameterization of sea spray aerosol production fluxes in the last decade, mainly focusing on the influencing factors of SSA production, the research progress of SSSFs, and the application of SSSFs in the models. The main environmental factors that alter the production flux in SSA include wind speed, sea surface temperature, wave state, salinity, surface active organic matter, etc. To better parameterize the SSA production flux, different expressions of SSSFs have been proposed. This paper mainly summarizes from different variables such as particle size distribution dependence, whitecap coverage, sea surface temperature dependence and wave state dependence. Moreover, many studies have incorporated different SSSFs in different GCMs and CTMs to evaluate the reasonableness of SSSFs and the climate impact of SSA emissions. Finally, we summarize the current results and inadequacy of SSA production flux parameterization, and put forward the prospect of future research direction.

Sea spray as a secondary source of chlorinated persistent organic pollutants? - Conclusions from a comparison of seven fresh snowfall events in 2019 and 2021

Secondary sources of persistent organic pollutants (POPs) gain in importance worldwide as primary sources decline. In this work, we aim to determine whether sea spray may be a secondary source of chlorinated POPs to the terrestrial Arctic, since a similar mechanism was proposed there only for the more water-soluble POPs. To this end, we have determined polychlorinated biphenyls and organochlorine pesticides concentrations in fresh snow and seawater collected in the vicinity of the Polish Polar Station in Hornsund in two sampling periods covering spring 2019 and 2021. To support our interpretations, we include also metal and metalloid, and stable hydrogen and oxygen isotopes analysis in those samples. A significant correlation was found between the concentrations of POPs and the distance from the sea at the sampling point, yet the confirmation of sea spray impact lies more in capturing an event with negligible long-range transport influence where the detected chlorinated POPs (Cl-POPs) matched in composition the compounds enriched in the sea surface microlayer, which is both a source of sea spray and a seawater microenvironment rich in hydrophobic substances.

Assessment of fine droplets (

Passive samplers are especially inefficient when collecting and measuring the finest particles in primary airborne spray drift far from the spray source. We describe a method to improve the measurement of <10 μm-sized droplets that become airborne during crop spray applications. An airblast sprayer was combined with Conventional (VMD 90 μm) and Low Drift (VMD 276 μm) nozzles. Downwind droplet concentrations were measured at six sampling distances (5, 10, 15, 20, 25, and 30 m) from the sprayer pathway using an Optical Particle Counter (OPC). The instrument simultaneously measures particle mass (μg m−3) and particle number (n). Three particle size ranges were considered (<1.0, 1.0–2.5, and 2.5–10.0 μm). Weather conditions were monitored to ensure optimal spray drift generation as dictated by the ISO22866:2005 which allowed comparison of the two nozzle technologies. Significant downwind particle mass and number increases were observed using proposed methodology compared to the background level with either Conventional or Low Drift nozzles. As expected, more massive fine droplets (+55%) resulted with Conventional nozzles. Interestingly, the Low Drift nozzles highlighted their potential to generate more fine particles (<1.0 μm) at 25 and 30 m from the sprayer. This study verified the potential to use OPCs to assess drift and understand particle size variation and dynamics during drift events.

Aptamer affinity-based microextraction in-line coupled to capillary electrophoresis mass spectrometry using a porous layer/nanoparticle -modified open tubular column

An aptamer affinity based microextraction column is developed to be directly in-line coupled to capillary electrophoresis-mass spectrometry (CE-MS) for analyzing mycotoxins in food samples. Single-stranded DNA aptamers for selective recognition of aflatoxin B1 (AFB1) and ochratoxin A (OTA) targets are co-immobilized via covalent bonds on the surface of the inlet end of a capillary, which is pre-modified with three-dimensional porous layer and gold nanoparticles to enhance the specific surface area and loading capacity. The outlet of the capillary is designed as a porous tip to serve as the spray source for injection to the mass spectrometry. All the necessary processes for pretreatment and analysis of a sample are accomplished in one injection, including aptamer affinity-based microextraction, CE separation and MS detection of analytes. AFB1 and OTA are simultaneously determined in a wide linear range with sample consumption of only 1 μL and the limit-of-detection as low as 1 pg/mL. The microextraction column exhibits excellent repeatability and stability, which can be used over 45 runs within a month with CE separation efficiency and only MS intensity slightly decreased. Mycotoxins in three kinds of cereal based infant foods are accurately analyzed using the proposed method. The study provides a robust and universal approach that would have potential applications in a variety of analytical fields based on selective molecular recognition coupling to CE-MS analysis.

Elemental Variability of PM2.5 Aerosols in Historical and Modern Areas of Jeddah, Saudi Arabia

Air particulate matter with a diameter of 2.5 µm (PM2.5) were assembled for a whole year from the historical Jeddah district. Additional PM2.5 aerosols were collected during the autumn and winter seasons from another newly constructed district in Jeddah city (Alnaeem). The annual concentration of the total mass of the PM2.5 aerosols from the historical Jeddah site was found to be 43 ± 6 µg/m3. In addition, the average of the total mass concentration at the Alnaeem site was 61 ± 14 µg/m3. These values were greater than the annual mass concentration of the air quality standards of the European Commission (25 µg/m3) and the World Health Organization (10 µg/m3). The elemental analysis of the collected fine atmospheric aerosols was achieved by energy dispersive X-ray fluorescence (EDXRF) with three secondary targets (CaF2, Ge, and Mo). Quantitative elemental analyses of twenty-two (22) elements were achieved starting from the low atomic number element (Na) up to the high atomic number element (Pb). Although the historical Jeddah site is not well organized, the elemental concentrations and total mass concentrations were lower than those of the other site. The statistical analyses including enrichment factors, correlation analysis, and the principal component analysis revealed more information about the source identification of the PM2.5 aerosols collected from both locations. It was recognized that the elements Al, Si, K, Ca, Ti, Mn, Fe, Rb, and Sr originated from a natural source. On the other hand, the elements Ta, Br, Pb, Sc, Ni, Cu, Zn, and S originated from anthropogenic sources. Finally, the elements Na, Cl, and Br came mainly from the sea spray source.

Grey relational based Taguchi analysis on heat transfer performances of direct oil spray cooling system for electric vehicle driving motor

In the present study, the grey relational based Taguchi analysis is conducted to evaluate the effect of influential factors on heat transfer performances of direct oil spray cooling system for electric vehicle driving motor. The influence of spray flow characteristics considering three nozzle types of spiral, full-cone and hollow-cone, coolant temperature (CT), heating capacity (HC), flow rate (FR) and distance between nozzle spray and heating source (D) are evaluated on heat transfer performances of maximum temperature, temperature uniformity, maximum injection pressure, heat transfer coefficient, friction factor and Nusselt number. The Taguchi analysis evaluates the effect of influential factors in terms of mean, range, influence order, F-value and percentage contribution while the grey relational analysis evaluates the combined parameter of two performances in terms of grey relational grade (GRG). The decreasing influence order of factors is evaluated as FR>HC>CT>D with corresponding percentage contributions of 39.16%, 33.99%, 14.16% and 12.68% for GRG of heat transfer coefficient and spray power consumption and FR>HC>D>CT with corresponding percentage contributions of 86.02%, 7.98%, 3.54% and 2.46% for GRG of Nusselt number and friction factor. An efficient direct oil spray cooling system could be fabricated for electric vehicle driving motor based on qualitative and quantitative effects of various influential factors on its heat transfer performances.

Direct C(sp3)-N Bond Formation between Toluene and Amine in Water Microdroplets.

Unlike the inertness of bulk water, water microdroplets exhibit some remarkable reactivities. We report that water microdroplets can directly produce stable C7H7+ cations (a combination of benzylic and tropylium cations) from toluene and other substrates at room temperature with a positive voltage (+4 kV) applied to the droplet spray source. The C7H7+ cation and the benzyl radical (C6H5CH2·) are both generated via hydroxyl radicals at the water-gas interface of the microdroplets. The C7H7+ signal is observed directly by mass spectrometry. Dissolved amines (primary, secondary, and tertiary) in the microdroplets can react with both C7H7+ and C6H5CH2· to form the corresponding alkyl C(sp3)-N coupling products in one step, which cannot be achieved in bulk water or other solvents. The products were identified using tandem mass spectrometry (MS2) and 1H NMR spectroscopy. Notably, the direct C(sp3)-N bond formation products were obtained in the absence of a catalyst. In the presence of a radical scavenger, the mass spectra of the C(sp3)-N coupling products are strongly suppressed, which supports the hypothesis that this reaction is driven by hydroxyl radicals generated in the water microdroplets. Taken together, these results show that water microdroplets provide a new method for direct one-step C(sp3)-N bond formation without the need for a metal catalyst.

Simultaneous quantitation of befotertinib (D-0316) and its metabolite D-0865 in human plasma by LC-MS/MS method

A sensitive and reliable method was developed to determine befotertinib (D-0316) and its metabolite D-0865 from human plasma by LC-MS/MS. The samples were prepared by simple protein precipitation and 2 µL of the supernatant were chromatographed on a C18 analytical column (ACE Excel 2 Super C18, 50 × 2.1 mm). Elution was performed with mobile phase A (10 mM ammonium acetate in water containing 1 % formic acid) and mobile phase B (acetonitrile containing 1 % formic acid) under a gradient program in a total run time of 4 min. Triple Quadruple 5500 equipped with Turbo Ion Spray source and multiple reaction monitoring (MRM) were used for the analysis detection. The transitions were m/z 568.3 → 72.1 m/z (befotertinib), m/z 554.2 → 497.2 (D-0865), and m/z 455.2 → 164.9 (verapamil, internal standard). According to the Chinese Pharmacopeia Commission and ICH Harmonised Guideline for Bioanalytical Method Validation, this method was validated within the spectrum of its accuracy, precision, selectivity, linearity, recovery, matrix effect, and stability. This LC-MS/MS method was successfully applied for the quantitation of befotertinib and its metabolite D-0865 in human plasma during the pharmacokinetics study of befotertinib in non-small cell lung cancer (NSCLC) patients.

Aqueous microdroplets enable abiotic synthesis and chain extension of unique peptide isomers from free amino acids

Amide bond formation, the essential condensation reaction underlying peptide synthesis, is hindered in aqueous systems by the thermodynamic constraints associated with dehydration. This represents a key difficulty for the widely held view that prebiotic chemical evolution leading to the formation of the first biomolecules occurred in an oceanic environment. Recent evidence for the acceleration of chemical reactions at droplet interfaces led us to explore aqueous amino acid droplet chemistry. We report the formation of dipeptide isomer ions from free glycine or L-alanine at the air-water interface of aqueous microdroplets emanating from a single spray source (with or without applied potential) during their flight toward the inlet of a mass spectrometer. The proposed isomeric dipeptide ion is an oxazolidinone that takes fully covalent and ion-neutral complex forms. This structure is consistent with observed fragmentation patterns and its conversion to authentic dipeptide ions upon gentle collisions and for its formation from authentic dipeptides at ultra-low concentrations. It also rationalizes the results of droplet fusion experiments that show that the dipeptide isomer facilitates additional amide bond formation events, yielding authentic tri- through hexapeptides. We propose that the interface of aqueous microdroplets serves as a drying surface that shifts the equilibrium between free amino acids in favor of dehydration via stabilization of the dipeptide isomers. These findings offer a possible solution to the water paradox of biopolymer synthesis in prebiotic chemistry.

Experimental development of a lake spray source function and its model implementation for Great Lakes surface emissions

Abstract. Lake spray aerosols (LSAs) are generated from freshwater breaking waves in a mechanism similar to their saltwater counterparts, sea spray aerosols (SSAs). Unlike the well-established research field pertaining to SSAs, studying LSAs is an emerging research topic due to their potential impacts on regional cloud processes and their association with the aerosolization of freshwater pathogens. A better understanding of these climatic and public health impacts requires the inclusion of LSA emission in atmospheric models, yet a major hurdle to this inclusion is the lack of a lake spray source function (LSSF), namely an LSA emission parameterization. Here, we develop an LSSF based on measurements of foam area and the corresponding LSA emission flux in a marine aerosol reference tank (MART). A sea spray source function (SSSF) is also developed for comparison. The developed LSSF and SSSF are then implemented in the Community Multiscale Air Quality (CMAQ) model to simulate particle emissions from the Great Lakes surface from 10 to 30 November 2016. Measurements in the MART revealed that the average SSA total number concentration was 8 times higher than that of LSA. Over the 0.01–10 µm aerosol diameter size range, the developed LSSF was around 1 order of magnitude lower than the SSSF and around 2 orders of magnitude lower for aerosols with diameters between 1 and 3 µm. Model results revealed that LSA emission flux from the Great Lakes surface can reach ∼105 m−2 s−1 during an episodic event of high wind speeds. These emissions only increased the average total aerosol number concentrations in the region by up to 1.65 %, yet their impact on coarse-mode aerosols was much more significant, with up to a 19-fold increase in some areas. The increase in aerosol loading was mostly near the source region, yet LSA particles were transported up to 1000 km inland. Above the lakes, LSA particles reached the cloud layer, where the total and coarse-mode particle concentrations increased by up to 3 % and 98 %, respectively. Overall, this study helps quantify LSA emission and its impact on regional aerosol loading and the cloud layer.

Implicit versus explicit vector management strategies in models for vector-borne disease epidemiology.

Throughout the vector-borne disease modeling literature, there exist two general frameworks for incorporating vector management strategies (e.g. area-wide adulticide spraying and larval source reduction campaigns) into vector population models, namely, the "implicit" and "explicit" control frameworks. The more simplistic "implicit" framework facilitates derivation of mathematically rigorous results on disease suppression and optimal control, but the biological connection of these results to real-world "explicit" control actions that could guide specific management actions is vague at best. Here, we formally define a biological and mathematical relationship between implicit and explicit control, and we provide mathematical expressions relating the strength of implicit control to management-relevant properties of explicit control for four common intervention strategies. These expressions allow the optimal control and basic reproduction number analyses typically utilized in implicit control modeling to be interpreted directly in terms of real-world actions and real-world monetary costs. Our methods reveal that only certain sub-classes of explicit control protocols are able to be represented as implicit controls, and that implicit control is a meaningful approximation of explicit control only when resonance-like synergistic effects between multiple explicit controls have negligible effects on population reduction. When non-negligible synergy exists, implicit control results, despite their mathematical tidiness, fail to provide accurate predictions regarding vector control and disease spread. Collectively, these elements build an effective bridge between analytically interesting and mathematically tractable implicit control and the challenging, action-oriented explicit control.

Soft Ionization Mass Spectrometry for Studying Noncovalent Interactions

Biochemistry and structural biology have benefited tremendously from the development of electrospray ionization and matrix-assisted laser desorption/ionization, the two most important soft ionization methods used in modern mass spectrometry. Of importance in this context is that noncovalently bound complexes can be maintained in the gas phase using appropriate sample preparation conditions and instrumental settings in ESI-MS and MALDI-MS. This allows one to determine the architecture and stoichiometry of large noncovalent complexes, the binding of small molecule ligands and cofactors, and often even noncovalent binding affinities, since bound and unbound states can be clearly resolved and quantified using MS. This article presents an overview of the research in this particular area undertaken by my research group at ETH Zurich. I will introduce a number of specialized technologies that we have available in our laboratory, including MALDI mass spectrometry with high-mass detection for measuring complexes with molecular weights in the 100s of kDa range; the so-called “gap sampler” technology for high-throughput experiments; and a temperature programmed spray source for ESI. A number of selected applications will then be presented, including the study of GPCRs and other membrane proteins and their complexes, the determination of the melting behavior of non-canonical nucleic acid structures, the investigation of heterogeneous protein complexes and protein-based capsids, and the investigation of the influence of protein post-translational modifications on noncovalent binding profiles.

Dry-deposition of inorganic and organic nitrogen aerosols in Xiamen Bay: Fluxes, sources, and biogeochemical significance

Increased dry deposition of nitrogen aerosols (aerosol-N) as a result of anthropogenic emissions has caused large negative impacts on marine ecosystems. We monitored the number concentrations and sizes of inorganic nitrogen aerosols (aerosol-IN: NH4+ and NO3−) and organic nitrogen aerosols (aerosol-ON: methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, and triethylamine) by single-particle aerosol mass spectrometry (SPAMS) during the warm season (WS) and cold season (CS) of 2013 and 2015 in Xiamen Bay. The mean hourly number concentration of aerosol-IN (874/h) overwhelmed that of aerosol-ON (103/h), accounting for 83.9 ± 16.1% of aerosol-N. More than 90% of aerosol-N was concentrated in the condensation mode (0.1–0.5 μm) and droplet mode (0.5–2.0 μm). Aerosol-IN was the main contributor (80.1–94.2%) to aerosol-N deposition. New production potentially supported by the ocean's external nitrogen supply provided aerosol-N input of 11.51–11.96 g C m−2 yr−1, which contributed 17.5–18.2% of total new production in the southern East China Sea. Four potential sources of aerosol-N were identified based on the results of positive matrix factorization analysis, including secondary formation (F1), biogenic source (F2), sea spray, soil dust, biomass burning (F3), and anthropogenic sources (F4). Aerosol-N concentrations in Xiamen Bay were mainly affected by the ocean air masses during the WS and inland air masses during the CS. The percentages of aerosol-N at each backward trajectory cluster showed that the inland air masses brought more aerosol-IN emitted from biomass burning, soil dust, and secondary formation sources, whereas the ocean air masses brought more aerosol-ON emitted from a marine biogenic source into Xiamen Bay. This study provides an example of determining the number concentrations and sizes of IN and ON in aerosols by SPAMS, and helps us further understand the dry deposition and sources of IN and ON in aerosols in Xiamen Bay.