Size Range Research Articles

Silver Nanoparticulate Carriers: A Significant Development in Nanotechnology

Background: For centuries, silver has been known for its anti-bacterial effects. It also helps in the prevention and control of various infections. Silver, when synthesized in nano-size, is much more effective, so the trend of using silver nanoparticles in treating mild bacterial diseases to deadly infectious diseases has increased rapidly. Methods: Silver nanoparticles can be synthesized by physical, chemical, and biological methods. Nanoparticles are developed in different shapes and have a wide range of sizes, with the purpose of controlling the release rate and content of the drug’s dose. The nanoparticles can be administered via oral, pulmonary, dermal, and intravenous routes. Results: Silver nanoparticles have been used in treating diseases, such as cancers, diabetes, etc., by targeted drug delivery and in cosmetics, wound healing, diagnostics, water purifying, bio-imaging, air purification, etc. The research on the novel applications of silver nanoparticles merits its medical application, and this utility aspect is granting patented technologies. The utilization of silver nanoparticles has enhanced in recent times due to their effectiveness in the specified diseased state. Conclusion: Studies have indicated that the drugs developed using silver nanoparticles manifest safety as they are biocompatible; thus, silver nanoparticles display a promising role in developing futuristic medical therapeutic strategies.

Ecofriendly biosynthesis of copper nanoparticles from novel marine S. rhizophila species for enhanced antibiofilm, antimicrobial and antioxidant potential

Marine microorganisms offer a promising avenue for the eco-friendly synthesis of nanoparticles due to their unique biochemical capabilities and adaptability to various environments. This study focuses on exploring the potential of a marine bacterial species, Stenotrophomonas rhizophila BGNAK1, for the synthesis of biocompatible copper nanoparticles and their application for hindering biofilms formed by monomicrobial species. The study begins with the isolation of the novel marine S. rhizophila species from marine soil samples collected from the West coast region of Kerala, India. The isolated strain is identified through 16S rRNA gene sequencing and confirmed to be S. rhizophila species. Biosynthesis of copper nanoparticles using S. rhizophila results in the formation of nanoparticles with size of range 10-50 nm. The nanoparticles exhibit a face-centered cubic crystal structure of copper, as confirmed by X-Ray Diffraction analysis. Furthermore, the synthesized nanoparticles display significant antimicrobial activity against various pathogenic bacteria and yeast. The highest inhibitory activity was against Staphylococcus aureus with a zone of 27±1.00 mm and the least activity was against Pseudomonas aeruginosa with a zone of 22±0.50 mm. The zone of inhibition against Candida albicans was 16±0.60 mm. The antibiofilm activity against biofilm-forming clinical pathogens was evidenced by the antibiofilm assay and SEM images. Additionally, the copper nanoparticles exhibit antioxidant activity, as evidenced by their scavenging ability against DPPH, hydroxyl, nitric oxide, and superoxide radicals, as well as their reducing power in the FRAP assay. The study highlights the potential of the marine bacterium S. rhizophila BGNAK1 for the eco-friendly biosynthesis of copper nanoparticles with diverse applications. Synthesized nanoparticles exhibit promising antibiofilm, antimicrobial, and antioxidant properties, suggesting their potential utility in various fields such as medicine, wastewater treatment, and environmental remediation.

A Review on Solid Lipid Nanoparticles as Nano Drug Delivery Transporters

Abstract: Solid lipid nanoparticles (SLN) have several potential uses in research for medicine such as drug discovery and drug delivery, an area at the forefront of evolving area of nanobiotechnology. In general, SLNs were created to address the drawbacks of conventional colloidal carriers, including emulsions, liposomes, and polymeric nanoparticles since they provide various advantages such as favourable release profiles and tailored drug delivery with outstanding physical-chemical stability. Solid lipid nanoparticles are spherical solid lipid particles that are distributed in water or an aqueous surfactant solution and are in the nanometer size range. Therefore, SLN is used to deliver hydrophilic and lipophilic drugs. The review article focuses on various aspects of SLN including the structure, the influence of excipients, the drug incorporation model, the principle of release, the method of preparation, characterization, the route of administration and biodistribution, and the application of SLN.

Discovery and Analysis of Microplastics in Human Bone Marrow

The health implications of human exposure to microplastics (MPs) have raised significant concerns. While evidence indicates MPs can accumulate in closed human organs like the heart, placenta, and blood, there is no available data on MP exposure specifically within the human bone marrow. To fill the research gap, this study detected the concentration of microplastics (MPs) in bone marrow samples by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and assessed the size range and morphological characteristics of MPs by Laser Direct Infrared Spectroscopy (LD-IR) and scanning electron microscopy (SEM). Our study shows that MPs were present in all 16 bone marrow samples, with an average concentration of 51.29µg/g ranging from 15.37µg/g to 92.05µg/g. Five polymer types-polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyadiohexylenediamine 66 (PA66), and polypropylene (PP), were identified. PE was the most frequent polymer detected in the bone marrow, with an average concentration of 30.02µg/g ranging from 14.77µg/g to 52.57µg/g, with a detection rate of 93.75%. PS had the highest detection rate at 100% of bone marrow samples, while PVC and PA66 were found in 75% of samples each. LD-IR analysis revealed the identification of 25 polymer types, with an average abundance of 19.72 particles/g. Of these, 89.82% of the MPs were smaller than 100 μm. In summary, this study has, for the first time, demonstrated the presence of MPs are deeply embedded within human bone marrow, providing a basis for future investigations into their potential toxicological effects and underlying mechanisms affecting the hematopoietic system.

Fast and scalable ensemble learning method for versatile polygenic risk prediction

Polygenic risk scores (PRS) enhance population risk stratification and advance personalized medicine, but existing methods face several limitations, encompassing issues related to computational burden, predictive accuracy, and adaptability to a wide range of genetic architectures. To address these issues, we propose Aggregated L0Learn using Summary-level data (ALL-Sum), a fast and scalable ensemble learning method for computing PRS using summary statistics from genome-wide association studies (GWAS). ALL-Sum leverages a L0L2 penalized regression and ensemble learning across tuning parameters to flexibly model traits with diverse genetic architectures. In extensive large-scale simulations across a wide range of polygenicity and GWAS sample sizes, ALL-Sum consistently outperformed popular alternative methods in terms of prediction accuracy, runtime, and memory usage by 10%, 20-fold, and threefold, respectively, and demonstrated robustness to diverse genetic architectures. We validated the performance of ALL-Sum in real data analysis of 11 complex traits using GWAS summary statistics from nine data sources, including the Global Lipids Genetics Consortium, Breast Cancer Association Consortium, and FinnGen Biobank, with validation in the UK Biobank. Our results show that on average, ALL-Sum obtained PRS with 25% higher accuracy on average, with 15 times faster computation and half the memory than the current state-of-the-art methods, and had robust performance across a wide range of traits and diseases. Furthermore, our method demonstrates stable prediction when using linkage disequilibrium computed from different data sources. ALL-Sum is available as a user-friendly R software package with publicly available reference data for streamlined analysis.

A Scalable and Surfactant-Free Emulsion Method for Producing Microbeads from Varied Biomass Feedstocks.

Despite national and international regulations, plastic microbeads are still widely used in personal care and consumer products (PCCPs). These exfoliants and rheological modifiers cause significant microplastic pollution in natural aquatic environments. Microbeads from nonderivatized biomass like cellulose and lignin can offer a sustainable alternative to these nondegradable microplastics, but processing this biomass into microbeads is challenging due to limited viable solvents and high biomass solution viscosities. To produce biomass microbeads of the appropriate size range for PCCPs (ca. 200-800 μm diameter) with shapes and mechanical properties comparable to those of commercial plastic microbeads, we used a surfactant-free emulsion/precipitation method, mixing biomass solutions in 1-ethyl-3-methylimidazolium acetate (EMImAc) with various oils and precipitating with ethanol. While yield of microbeads within the target size range highly depends on purification conditions, optimized protocols led to >90% yield of cellulose microbeads. Kraft lignin was then successfully incorporated into beads at up to 20 wt %; however, higher lignin contents result in emulsion destabilization unless surfactant is added. Finally, the microbead shape and surface morphology can be tuned using oils of varying viscosities and interfacial tensions. Dripping measurements and pendant drop tensiometry confirmed that the higher affinity of cellulose for certain oil/IL interfaces largely controlled the observed surface morphology. This work thus outlines how biomass composition, oil viscosity, and interfacial properties can be altered to produce more sustainable microbeads for use in PCCPs, which have desirable mechanical properties and can be produced over a wide range of shapes and surface morphologies.

Laws of macroevolutionary expansion

Van Valen’s law of constant extinction postulates that in comparable ecological contexts, the probability for a taxon to survive to the next time interval is independent of how long it has already existed. The law implies that species do not age, that is, the survival probability from one time step to the next does not decrease with species’ age. While the original law describes survivorship over time, here we show that there is a counterpart to the law describing species dynamics in space. Indeed, the probability for a taxon to expand a step further in its range size does not depend on how large of a range the taxon already occupies. We show that such patterns of stochastically constant expansion are common in the global mammalian fossil record throughout the Cenozoic and are consistent with the mammalian species distribution in the present-day world. Intriguing is that the law in space holds best for the linear dimension of the range rather than for the range area. We interpret this as suggesting that species primarily expand via the frontier of their range; this process is known as leading-edge expansion in ecology. And while the difficulty of expanding in linear steps remains constant, the area gains diminish. In line with evolutionary theory collectively known as the Red Queen’s hypothesis, this suggests that the effectiveness of expansion saturates, even if species longevity does not. When interpreted in reverse, this explains from the macroevolutionary perspective why larger species ranges are associated with lower extinction risks.

Where are the provincial-level new records in China from the past 20 years, and which traits determine their shift directions?

Birds are sensitive to environmental changes and can drive range shifts rapidly due to their high mobility. Though previous studies have examined the associations between species traits and range shifts, whether species traits could still explain heterogeneity in shift directions remains poorly explored. Here, we compiled new bird records of China from 2000 to 2019 and analyzed species traits associated with apparent shift directions. We collected 350 provincial-level new records of birds belonging to 67 families of 22 orders. Of these, 32 are threatened, with 3 critically endangered, 11 endangered, and 18 vulnerable. Provinces in western China (i.e., Yunnan and Xizang) had relatively higher species richness of new recorded birds; this pattern was also reflected in the phylogenetic diversity we observed. In addition, provinces in northern China (i.e., Tianjin, Shandong, and Beijing) had relatively higher richness-controlled phylogenetic diversity. Phylogenetic overdispersion of new recorded bird communities was observed in 61.29% of provinces (19 of 31). The main shift directions indicated by new bird records were northward (with nearly 50% of birds moving NW, N and NE). Migration, hand-wing index (HWI), body mass, and range size are the four key factors that most significantly influence the shift directions in bird species, suggesting that bird movement toward newly suitable areas varies with species-specific traits. Together, these results demonstrate the importance of considering species ecological traits when predicting shift directions of birds.

Using spatial capture‐recapture models to estimate spotted hyaena (Crocuta crocuta) population density and assess the influence of sex‐specific covariates on space use and detection probability

AbstractDespite being resident or reintroduced to multiple South African protected areas, spotted hyaena (Crocuta crocuta) have been subject to limited population monitoring and are not managed in the same intensive way as other large carnivores. Considering the species' significant influence on ecosystem processes, robust estimates of population density are necessary to inform conservation management. In this study, we ran a single‐season camera trap survey in the Main Camp section of Addo Elephant National Park (Addo), South Africa, and used spatial capture‐recapture (SCR) models to estimate spotted hyaena population density. Spotted hyaena density was estimated to be 11.13 (± SE 1.96) individuals/100 km2, with an estimated abundance of 37 (± SE 6.44) individuals. Using our database of sexed spotted hyaena individuals, we found no significant difference for sex‐specific SCR parameters (baseline encounter probability and spatial scale parameter), suggesting the incorporation of sex‐specific information may not be as necessary for spotted hyaena as it is for territorial felids and other species with more pronounced differences in range size. Spotted hyaena density in Addo was comparable to previous SCR studies and towards the higher end of known densities. Our estimate provides an important baseline for monitoring reintroduction success in Addo, and we advocate for increased SCR monitoring of spotted hyaena in South African protected areas to inform a metapopulation approach to the species' management.

Study of hydrocyclone with flushing water device for sand washing of municipal sludge

Municipal sludge particles with size range between 0.045 and 0.2 mm were difficult to be precisely separated due to fine size distribution and high content of organic matter, resulting in low sand recycling efficiency. In view of the above problems, this paper proposed a flushing water device which was settled at the cone section of conventional hydrocyclone, aiming to utilize the supplementary water to strengthen the shear force field. Comparative test results showed that the organic matter content in the underflow product was significantly reduced after the addition of flushing water. Using the organic matter content and the sand recovery rate as the response index, the prediction models were established by using response surface optimization test. The influence order of different parameters on the response index was apex diameter, flushing device position and flow rate. Finally, an underflow product with organic matter content of 3.96 % and sand recovery rate of 48.03 % was obtained under the conditions of optimized parameter combinations. The research results can contribute to the development of a new method of residual sludge disposal that improves the sand washing efficiency and the cost-effectiveness of sludge treatment.

Osteosarcoma growth on trabecular bone mimicking structures manufactured via laser direct write

 This paper describes the direct laser write of a photocurable acrylate-based PolyHIPE (High Internal Phase Emulsion) to produce scaffolds with both macro- and microporosity, and the use of these scaffolds in osteosarcoma-based 3D cell culture. The macroporosity was introduced via the application of stereolithography to produce a classical “woodpile” structure with struts having an approximate diameter of 200 μm and pores were typically around 500 μm in diameter. The PolyHIPE retained its microporosity after stereolithographic manufacture, with a range of pore sizes typically between 10 and 60 μm (with most pores between 20 and 30 μm). The resulting scaffolds were suitable substrates for further modification using acrylic acid plasma polymerisation. This scaffold was used as a structural mimic of the trabecular bone and in vitro determination of biocompatibility using cultured bone cells (MG63) demonstrated that cells were able to colonise all materials tested, with evidence that acrylic acid plasma polymerisation improved biocompatibility in the long term. The osteosarcoma cell culture on the 3D printed scaffold exhibits different growth behaviour than observed on tissue culture plastic or a flat disk of the porous material; tumour spheroids are observed on parts of the scaffolds. The growth of these spheroids indicates that the osteosarcoma behave more akin to in vivo in this 3D mimic of trabecular bone. It was concluded that PolyHIPEs represent versatile biomaterial systems with considerable potential for the manufacture of complex devices or scaffolds for regenerative medicine. In particular, the possibility to readily mimic the hierarchical structure of native tissue enables opportunities to build in vitro models closely resembling tumour tissue.

Evaluation of wood chips terminal velocity and some morphological properties in a wind tunnel experiment

AbstractThe removal of wood dust and chips from the work area is also important for occupational health safety regulation and to avoid the risk of fire and dust explosion. Knowledge of the terminal velocity is an important condition for the effective and economical operation of commonly used wood dust-chip extraction systems. While the largest particles are important from the point of view of the operation of the extraction system, knowledge of the terminal velocity of small particles (under 1 mm) is desirable from the point of view of separation and occupational health safety. New measuring and calculation method is developed in order to determine the terminal velocity of wood particles. We built an experimental device to measure the terminal velocity of wood dust-chip particles, and using the experimental results, we modified the calculated terminal velocity based on the modified equivalent particle density (100–130 kg/m3) in the 1–150 μm size range. The terminal velocity of wood particles under 150 μm more and more deviates from the theoretical values. As a result of mechanical processing, the resulting wood particles’ shape is in most cases flat. The average thickness of the wood particles is mainly determined by the sawing parameters. The flat shape of particles increases the specific surface area in a certain extent depending on the distribution parameters.

Overlap between priority conservation areas and natural assets appeals to a shared responsibility for global primate conservation

Expanding protected areas (PAs) coverage to match countries’ conservation responsibility is vital to stemming global biodiversity loss. Uneven biodiversity distribution and conservation responsibility among countries pose challenges to the implementation of conservation targets, and currently diminish conservation effectiveness. Using primates as a global model, we evaluated the conservation responsibility of countries to assess if their PA coverage adequately meets their conservation responsibility. We quantified spatial national responsibility for primate species conservation in each country from their range size of priority conservation areas (PCAs) and protected areas coverage on PCAs. We identified the high-responsibility countries for global primate conservation as countries that held > 1 % of global PCAs. We paid particular attention to the circumstances associated with PCAs in the least developed countries, especially the overlap between PCAs and the areas containing natural assets (natural assets areas). Seventeen countries were identified as high-responsibility countries that in total covered 84 % area of global PCAs. Current protected areas only covered less than 50 % of PCAs for fifteen of these high-responsibility countries. Among these fifteen countries, four countries (DR Congo, PA coverage: 19 %; Myanmar, 9 %; Madagascar, 29 %; Laos, 22 %) were the least developed countries. Most existing PCAs (95 %; SD 6 %) in these 17 countries are located within natural assets areas, which creates tension between primate conservation and local development. Global primate conservation is a shared responsibility among the international community. Developing countries have greater responsibility than most because of the overlapping of their PCAs with natural assets areas. For developing countries to fulfill their conservation responsibilities requires international conservation resources (funding support and cooperation). Protected areas expansion has to be matched with a realizable target for each country to avoid crippling conflicts between conservation and local development. Community-based management models, including other effective area-based conservation measures, may reduce potential conflict and improve conservation effectiveness.

Greening the production of polymeric submicron particles by membrane-based manufacturing processes: A comparative analysis

The production of polymeric particles is the subject of extensive research in various fields and the interest in this area extends to the development of new sustainable production processes. The use of membrane technology has enabled the redesign of many traditional production processes with enormous impact in terms of product quality, reduction of energy consumption, high efficiency, productivity and reproducibility. In the present work, two alternative methodologies for the production of polycaprolactone (PCL) particles based on the use of membrane processes were investigated: i) membrane emulsification (ME) combined with solvent diffusion and ii) membrane nanoprecipitation (MN). ME/solvent diffusion is a widely applied technique for the production of microparticles, but its use for nanosized particles is still limited. On the other hand, MN is currently being investigated for its potentiality in the production of nanoparticles.In the present work, the performance of the two processes is compared in terms of: i) product quality (highly monodisperse particles in the nanometers range of size, ii) maximum productivity (expressed as mass of particles produced over time) under mild operating conditions (reduced mechanical stress), iii) environmental impact (assessed on the basis of the metrics established by the Green Aspiration Level (GAL)).

Design of Modular, 3D‐Printed Millifluidic Mixers to Enable Sequential NanoPrecipitation (SNaP) for the Tunable Synthesis of Drug‐Loaded Nanoparticles and Microparticles

AbstractSequential NanoPrecipitation (SNaP) is a nascent controlled precipitation process for the tunable formation of polymeric particles for drug delivery and bioimaging. While SNaP utilizes the same self‐assembly principles as one‐step Flash NanoPrecipitation, SNaP is a two‐step assembly process in which the particle core formation is initiated during a first mixing step followed by particle stabilization in a second mixing step. Current SNaP experimental set‐ups use commercial millifluidic mixers connected in series, which have several limitations, including the inability to access short inter‐mixer delay times (Td). A robust, 3D‐printed, modular mixer design that enables access to short Td's (〈 25 ms) not previously accessible is reported. For the first time, it is demonstrated that decoupling the assembly steps improves control over particle size, expanding the attainable size range to include both nanoparticles and microparticles. It is empirically proven that inter‐mixer Td is a key parameter for particle size control and that particle size scales with Td in agreement with Smoluchowski's model of diffusion‐limited growth. The formation of particles ranging in size from 160 nm to 1.2 µm is shown. Finally, the applicability of the new mixers is established by encapsulating fluorophores and therapeutics into particles for the first time via SNaP.

Using DPF to Control Particulate Matter Emissions from Ships to Ensure the Sustainable Development of the Shipping Industry

PM (particulate matter) emissions from ships are the main sources of marine atmosphere pollution. Controlling the emissions of particulate matter from ships is related to the sustainable development of the shipping industry. To reduce PM emissions from marine four-stroke diesel engines, DPFs are effective. Our results show that DPF had more than 90% capturing efficiency for both the number and mass emissions of PM, and the capturing efficiency for the accumulation mode was higher than that of the nuclear mode. DPF can also significantly reduce the chemical components of PM in marine diesel exhaust gas. The removal efficiencies for OC and EC were 89.7–91.6% and 84.8–92.8%, respectively, with each particle size range showing over 80% efficiency. SO42− was the ion with the highest content, followed by NH4+, NO3−, Na+, NO2−, and Cl−, with their reduced proportions remaining consistent with the removal efficiency of particulate matter. DPF can also effectively reduce PAH content and toxicity. The use of DPF can greatly improve the impact of ship emissions on the marine atmospheric environment. The appropriate DPF with the best performance can be selected according to the exhaust parameters and particle size distributions with different characteristics.

Microbeads in exfoliating products: occurrence, abundance, and potential for water contamination in Ho Chi Minh City, Vietnam

Microbeads in exfoliating products are a significant source of microplastics entering aquatic ecosystems. This study characterized microbeads in popular facial scrub and body scrub products from Ho Chi Minh City, Vietnam, to quantify abundances and estimate emissions. A selection of facial scrub and body scrub cleansers were collected from local markets and analyzed to quantify microbead properties including the size, color, mass, and abundance of microbeads in the exfoliating cleansers. Results revealed a wide range of microbead sizes (66–1012 μm) and different shapes and colors within and between products. Most contained heterogenous particles of white, green, blue, red, brown, and black spherical microbeads. The range of microbead abundance was 236–942 particles per gram of product. Annual microbead emissions from the use of these products in Ho Chi Minh City were estimated based on population and usage data. The total annual emission of microbeads from facial and body scrubs in Ho Chi Minh City amounted to 1.3 billion microbeads. On a per capita basis, this equaled 880 microbeads per person annually discharged into the local water environment. According to the study, a preliminary calculation indicated that approximately 2640 microbeads were released per year per female student in Ho Chi Minh City. By providing an initial ssessment of microbead pollution arising specifically from personal care items in Vietnam, this study raises awareness of microplastics introduction into Asian coastal zones via cosmetic products. The baseline data establishes a foundation for further investigations. This represents an important step in quantifying and addressing an emerging microplastic source in the region.

Effect of alternative natural diet on microplastic ingestion, functional responses and trophic transfer in a tri-trophic coastal pelagic food web

The patchy distribution of microplastics (MP) and their size range similar to planktonic organisms, are likely to have major ecological consequences, through MP ingestion, food dilution, and transfer across trophic levels. Our study applied a community module using tritrophic food chain with zooplankton as prey, and a planktivorous seabass fry as predator. We conducted a series of feeding experiments and recorded the direct uptake of MP under six different concentrations ranging from 25 to 800 particles L−1. We also estimated the indirect transfer of MP via trophic link. The ingestion rates for Brachionus plicatilis, Mesocyclops isabellae, and Lates calcarifer, were 3.7 ± 0.3 MP ind−1 min−1, 1.69 ± 0.1 MP ind−1 min−1, and 3.51 ± 0.52 MP ind−1 h−1, respectively. In the presence of a natural diet, rotifers and copepods ingested significantly lower number, whereas, fish fry ingested a higher number of MP, suggesting further vulnerability to the consumers of MP-contaminated fish and potential biomagnification at higher trophic levels. Overall, the MP uptake rate increased with increasing concentration, and finally leveled off, indicating a type II functional response to MP concentration. The presence of natural diet led to a lower Km value. In the indirect transfer experiment, 74 % of B. plicatilis and 78 % of M. isabellae individuals were contaminated with MP, when offered as prey. Brachionid mastax and MP particles were observed in the gut of copepods. The fish fry gut content also recorded brachionid mastax, MP-contaminated copepods, and MP particles, showing direct evidence of trophic transfer pointing to a cascading effect on higher trophic levels including humans via piscivory.

Electrodynamic dust shield efficiency characterisation under UV in vacuum for lunar application

Dust mitigation is one of the most crucial aspects of extraterrestrial exploration. This paper presents a series of experiments on the electrodynamic dust shield (EDS) and how UV radiation affects its efficiency on selected lunar simulants (LHS-1 and LMS-1) across a range of particle sizes, quantities, and surface materials. In this experimental study, VUV is used with a 1500V AC electric field to mobilise the dust particles resting on either glass, Kapton, or Beta cloth inside a vacuum chamber at ∼10-6 mbar. The dust removal efficiency is characterised by two quantifying methods: weighing and solar array light transmission. The experimental results show that EDS activation under continuous UV exposure on the simulant particles improves the dust removal rate by 40 to 80 percentage points across all surfaces, with the exception of certain particle size ranges on Beta cloth. The primary force facilitating particle mobilisation was identified as the repulsive electrostatic force, enhanced by ionising mechanisms such as photoemission.

Indoor/Outdoor airborne microbiome characteristics in residential areas across four seasons and its indoor purification

Bioaerosols are more likely to accumulate in the residential environment, and long-term inhalation may lead to a variety of diseases and allergies. Here, we studied the distribution, influencing factors and diffusion characteristics of indoor and outdoor microbiota pollution in six residential buildings in Guangzhou, southern China over a period of one year. The results showed that the particle sizes of bioaerosol were mainly in the range of inhalable particle size (<4.7 μm) with a small difference among four seasons (74.61 % ± 2.17 %). The microbial communities showed obvious seasonal differences with high abundance in summer, but no obvious geographical differences. Among them, the bacteria were more abundant than the fungi. The dominant microbes in indoor and outdoor environments were similar, with Anoxybacillu, Brevibacillus and Acinetobacter as the dominant bacteria, and Cladosporium, Penicillium and Alternaria as the dominant fungi. The airborne microbiomes were more sensitive to temperature and particulate matter (PM2.5, PM10) concentrations. Based on the Sloan neutral model, bacteria were more prone to random diffusion than fungi, and the airborne microbiome can be randomly distributed in indoor and outdoor environments and between the two environments in each season. Bioaerosol in indoor was mainly from outdoor. The health risk evaluation showed that the indoor inhalation risks were higher than those outdoor. The air purifier had a better removal efficiency on 1.1–4.7 μm microorganisms, and the removal efficiency on Gram-negative bacteria was better than that on Gram-positive bacteria. This study is of great significance for the risk assessment and control of residential indoor bioaerosol exposure.