Search

To investigate the influence of the inflow angle on the hydraulic loss and internal flow fields of a vertical mixed-flow pump device, unsteady numerical simulations were performed under different inflow angles ( θ = 0°, 10°, 20°, and 30°). The calculation results were validated using an external characteristic test at an inflow angle of 0°. The entropy production theory was applied to analyse the energy loss and dissipation rate distribution in a vertical mixed-flow pump device under different inflow angles. Influenced by asymmetric inflow, the design point of the external characteristics deviated towards the overload flow rate, and the maximum deviations were obtained under 1.2 Q des, whereas the influence of the inflow angle on the internal flow fields was the most significant under the part-load flow rate. When the inflow angle increased from 0° to 30°, the total entropy production in the pump device increased by 18.35% under 0.6 Q des, and indirect dissipation accounted for the largest proportion. The internal flow patterns in the impeller and guide vane were also distorted by asymmetric inflow. The indirect dissipation rate on the suction side of the impeller blade, interface between the impeller and diffuser, and pressure side of the guide vane increased significantly with an increase in the inflow angle. To restrain the influence of asymmetric inflow, it is of great significance to optimise the hydraulic design structure of the inflow runner. In this study, a middle spacer pier was used to improve the operational efficiency of the pump device.

In order to investigate the influence of asymmetric inflow on the internal flow fields of a vertical mixed-flow pump, numerical simulation of unsteady flow was carried out under four inflow angles ( θ = 0°, 10°, 20°, and 30°). The reliability of the calculation results was validated through an external characteristic experiment. The fluctuation value of the pressure was defined to obtain the transient pressure fluctuation intensity distribution. Three monitoring points were arranged to compare pressure fluctuation characteristics under different inflow angles. The results suggested that the increase in the inflow angle caused the design operation points to deviate to the over-load flow rate. When the inflow angle increased from 0° to 30°, the axial velocity distribution coefficient and weighted average angle at the inflow runner outlet both decreased. The overall transient pressure fluctuation intensity inside the impeller increased, especially on the pressure side of the blade. Additionally, the transient pressure fluctuation intensity on the pressure side of the guide vane also increased significantly. As a result, the amplitude of pressure fluctuation at the dominant frequency of each monitoring point increased. Relatively speaking, the negative influence of asymmetric inflow on the operational stability of the pumping station was further extended under the part-load flow rate.

Breath-borne volatile organic compounds (VOCs) have been increasingly studied as non-invasive biomarkers in both medical diagnosis and environmental health research. Recently, changes in breath-borne VOC fingerprints were demonstrated in rats and humans following pollutant exposures. In this study, the eukaryotic model

Microorganisms residing in the human respiratory tract can be exhaled, and they constitute a part of environmental microbiotas. However, the expiratory microbiota community and its associations with environmental microbiotas remain poorly understood. Here, expiratory bacteria and fungi and the corresponding microbiotas from the living environments were characterized by DNA amplicon sequencing of residents' exhaled breath condensate (EBC) and environmental samples collected from 14 residences in Nanjing, China. The microbiotas of EBC samples, with a substantial heterogeneity, were found to be as diverse as those of skin, floor dust, and airborne microbiotas. Model fitting results demonstrated the role of stochastic processes in the assembly of the expiratory microbiota. Using a fast expectation-maximization algorithm, microbial community analysis revealed that expiratory microbiotas were differentially associated with other types of microbiotas in a type-dependent and residence-specific manner. Importantly, the expiratory bacteria showed a composition similarity with airborne bacteria in the bathroom and kitchen environments with an average of 12.60%, while the expiratory fungi showed a 53.99% composition similarity with the floor dust fungi. These differential patterns indicate different relationships between expiratory microbiotas and the airborne microbiotas and floor dust microbiotas. The results here illustrated for the first time the associations between expiratory microbiotas and indoor microbiotas, showing a potential microbial exchange between the respiratory tract and indoor environment. Thus, improved hygiene and ventilation practices can be implemented to optimize the indoor microbial exposome, especially in indoor bathrooms and kitchens.

Uncertainties regarding optimized air pollution control remain as the underlying mechanisms of city-specific ambient particulate matter (PM)-induced health effects are unknown. Here, water-soluble extracts of PMs collected from four global cities via automobile air-conditioning filters were consecutively injected three times by an amount of 1, 2, and 2 mg into the blood circulation of Wistar rats after filtration by a 0.45 μm pore size membrane. Acute health effects, such as immune and inflammatory responses and hemorrhage in alveoli, were observed right after the PM extraction injection. Significant differences between cities in biomarker tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) levels were detected following the second and third PM injections. Rats’ inflammatory responses varied substantially with the injections of city-specific PMs. Repeated PM extract exposure rendered the rats more vulnerable to subsequent challenges, and downregulation of certain microRNAs was observed in rats. Among the studied miRNAs, miR-125b, and miR-21 were most sensitive to the PM exposure, exhibiting a negative dose–response-type relationship with a source-specific PM (oxidative potential) toxicity (r² = 0.63 and 0.57; p-values < 0.05). The results indicated that city-specific PMs could induce different health effects by selectively regulating different miRNAs, and that certain microRNAs, e.g., miR-125b and miR-21, may be externally mediated to neutralize PM-related health damages.

HighlightsThe maximum SCCA concentration was achieved at a C/N ratio of 25 with 18 days of fermentation.The highest VFAs and LA were produced at C/N ratios of 12.7 and 35, respectively, after 12 days of fermentation.The unit energy value of SCCAs for drop-in fuel production was 50.5% higher than that of methane.The dominant bacteria changed from Clostridium to Lactobacillus with increasing C/N ratio.Abstract. Advancing technologies to produce short-chain carboxylic acids (SCCAs) from agricultural waste are expected to be more economical and efficient. This study presented a new attempt to enhance SCCA production from co-digestion of swine manure and corn silage with the carbon-nitrogen (C/N) ratio adjusted from 12.7 to 50.2. Results showed that the maximum SCCA concentration of 26,214 ±2948 mg COD L-1 was achieved at a C/N ratio of 25 with 18 days of digestion, and the concentrations of lactic acid (LA) and volatile fatty acids (VFAs) were 8700 ±1060 mg COD L-1 and 17,514 ±1888 mg COD L-1, respectively. The LA content first increased and then slightly decreased with increasing C/N ratio, and the maximum LA concentration was 468.5 ±44.3 mg COD g-1 VSadded (VSadded means added fermentation material is calculated as volatile solids) at a C/N ratio of 35 at 12 days of digestion. VFAs showed an opposite trend, with a maximum VFA concentration of 601.1 ±42.4 mg COD g-1 VSadded found at a C/N ratio of 12.7 after 12 days of digestion. Potential energy analysis of the highest SCCA production showed that the unit energy value of SCCAs for drop-in fuel production was 50.5% higher than that of methane. Analysis of the microbial community showed that the dominant bacterial groups changed gradually from butyric acid-producing bacteria (Clostridium) to lactic acid-producing bacteria (Lactobacillus) as the C/N ratio increased from 12.7 to 50.2. Keywords: Anaerobic digestion, Corn silage, Lactic acid, Short-chain carboxylic acids, Swine manure.

Antibiotic resistance is a global public health concern. Antibiotic usage in pigs makes swine wastewater (SW) a reservoir for antibiotic resistance genes (ARGs). SW is usually stored and treated in a three-chamber anaerobic pond (3-CAP) in medium and small pig farms in northern China. However, the yet unexplored presence of ARGs in SW during 3-CAP treatment may result in ARGs spreading into the environment if farmers apply SW to farmland as a liquid organic fertilizer. This study investigated the profiles of and changes in ARGs in SW during its treatment in 3-CAP over four seasons and analyzed the correlation between ARGs and bacterial phenotypes, along with the physicochemical parameters of the water. The results revealed that ARG abundance decreased considerably after 3-CAP treatment in April (47%), October (47%), and December (62%) but increased in May (43%) and August (73%). The ARG copies in the influent and other SW samples increased significantly from 107 copies/mL in April to 109 copies/mL in October and were maintained in December. The increase in ARG abundance was not as rapid as the growth of the bacterial population, resulting in lower relative abundance in October and December. Bacterial communities possessed more sul1 and tetM genes, which were also positively correlated with mobile genetic elements. After the 3-CAP treatment, 16% of antibiotics and 60% of heavy metals were removed, and both had a weak correlation with ARGs. Predicted phenotypes showed that gram-positive (G+) and gram-negative (G−) bacteria have different capacities for carrying ARGs. G+ bacteria carry more ARGs than G− bacteria. This study revealed the persistence of ARGs in SW after 3-CAP treatment over different seasons. Applying SW in the proper month will mitigate ARG dissemination to the environment.

To reduce cavitation-induced pressure fluctuations in a mixed-flow pump under impeller inflow distortion, the dynamic pressure signal at different monitoring points of a mixed-flow pump with a dustpan-shaped inlet conduit under normal and critical cavitation conditions was collected using high-precision digital pressure sensors. Firstly, the nonuniformity of the impeller inflow caused by inlet conduit shape was characterized by the time–frequency-domain spectra and statistical characteristics of pressure fluctuation at four monitoring points (P4–P7) circumferentially distributed at the outlet of the inlet conduit. Then, the cavity distribution on the blade surface was captured by a stroboscope. Lastly, the characteristics of cavitation-induced pressure fluctuation were obtained by analyzing the time–frequency-domain spectra and statistical characteristic values of dynamic pressure signals at the impeller inlet (P1), guide vanes inlet (P2), and guide vanes outlet (P3). The results show that the flow distribution of impeller inflow is asymmetric. The pav values at P4 and P6 were the smallest and largest, respectively. Compared with normal conditions, the impeller inlet pressure is lower under critical cavitation conditions, which leads to low pav, pp-p and a main frequency amplitude at P1. In addition, the cavity covered the whole suction side under H = 13.6 m and 15.5 m, which led the pp-p and dominant frequency amplitude of pressure fluctuation at P2 and P3 under critical cavitation to be higher than that under normal conditions.

Depending on their concentrations, sizes, and types, particulate matters of biological origins (bioPM) significantly affect human health. However, for different air environments, they are not well characterized and can vary considerably. As an example, we investigated the bioPM differences at an urban (Beijing) site and a rural (Wangdu) site in the North China Plain (NCP) using an online monitoring instrument, an ultraviolet aerodynamic particle sizer (UV-APS), the limulus amebocyte lysate (LAL) assay, and a high-throughput sequencing method. Generally, lower concentrations of viable bioPM (hourly mean: 1.3 × 103 ± 1.6 × 103 m−3) and endotoxin (0.66 ± 0.16 EU/m3) in Beijing were observed compared to viable bioPM (0.79 × 105 ± 1.4 × 105 m−3) and endotoxin (15.1 ± 23.96 EU/m3) at the Wangdu site. The percentage of viable bioPM number concentration in the total PM was 3.1% in Beijing and 6.4% in Wangdu. Approximately 80% of viable bioPM was found to be in the range from 1 to 2.5 μm. Nevertheless, the size distribution patterns for viable bioPM at the Beijing and Wangdu sites differed and were affected by PM pollution, leading to distinct lung deposition profiles. Moreover, the distinct diurnal variations in viable bioPM on clean days were dimmed by the PM pollution at both sites. Distinct bacterial community structures were found in the air from the Beijing and Wangdu sites. The bacterial community in urban Beijing was dominated by genus Lactococcus (49.5%) and Pseudomonas (15.1%), while the rural Wangdu site was dominated by Enterococcus (65%) and Paenibacillus (10%). Human-derived genera, including Myroides, Streptococcus, Propionibacterium, Dietzia, Helcococcus, and Facklamia, were higher in Beijing, suggesting bacterial emission from humans in the urban air environment. Our results show that different air harbors different biological species, and people residing in different environments thus could have very different biological particle exposure.

To investigate the influence of the lateral inflow on the vortical structures and hydraulic losses inside the mixed-flow pump, entropy production, and Q-criterion were applied to numerical simulation analysis of transient flow. Three inflow runner schemes were designed to compare the effects of the middle-isolated pier and rear wall of the “ω” structure on restraining the occurrence and transmission of a vortex and stabilizing the internal flow state of the pump device. The results showed that when the inflow condition transformed from parallel inflow to lateral inflow, the design efficiency and head deviated toward the over-load flow rate, and the maximum deviations were obtained under the over-load flow rate, reaching 4.79% and 50.35%, respectively. The hydraulic losses and vortical structures increased to a large extent, influenced by the lateral inflow, particularly the flow region near the impeller hub. The setting of the vortex suppression facilities effectively reduced the deviation ratios in the design efficiency and head, which decreased to 1.31% and 7.59%, respectively. The vorticity intensity and entropy dissipation rate were also significantly decreased. By contrast, the rear wall of the “ω” structure had a greater stabilization effect on the internal flow patterns than that of the middle-isolated pier.

The axial flow pump is a low head, high discharge pump usually applicable in drainage and irrigation facilities. A certain gap should be reserved between the impeller blade root and the impeller hub to ensure the blade adjustability to broaden the high-efficiency area. The pressure difference between its blade surface induces leakage flow in the root clearance region, which decreases hydraulic performance and operational stability. Therefore, this study was carried out to investigate the effect of root clearance on mechanical energy dissipation using numerical simulation and entropy production methods. The numerical model was validated with an external characteristics test, and unsteady flow simulations were conducted on the axial flow pump under four different root clearance radii. The maximum reductions of 15.5% and 6.8% for head and hydraulic efficiency are obtained for the largest root clearance of 8 mm, respectively. The dissipation based on entropy theory consists of indirect dissipation and neglectable direct dissipation. The leakage flow in the root clearance led to the distortion of the impeller&rsquo, s flow pattern, and the indirect dissipation rate and overall dissipation of the impeller increased with increasing root clearance radius. The inflow pattern in the diffuser was also distorted by leakage flow. The diffuser&rsquo, s overall dissipation, indirect dissipation rate on the blade surface, and indirect dissipation rate near inlet increased with increasing root clearance radius. The research could serve as a theoretical reference for the axial flow pump&rsquo, s root clearance design for performance improvement and operational stability.

Biogas digestate is a reservoir of antibiotic resistance genes (ARGs) and could pose a high health risk to both human and animals if the host microorganisms of ARGs become aerosolized. The purpose of this study was to investigate the diversity and relative abundance characteristics of aerosol-loaded ARGs from biogas digestate during storage, and to explore whether the change of ARGs in biogas digestate directly affect the dispersion of aerosol-loaded ARGs. This study reported for the first time that 28 of 42 ARG subtypes detected in the biogas digestate could be dispersed to the atmosphere via aerosol dispersion in a lab-scale dynamic emission vessels experiment. The relative abundance or diversity of ARGs in aerosols were different from that in biogas digestate, and no significant correlation were observed between the relative abundance of ARGs in biogas digestate and aerosols. The dominant ARGs were tetracycline resistance genes in biogas digestate and β-lactam resistance genes in aerosols. The process of biogas digestate storage reduced the total relative abundance of targeted ARGs in biogas digestate, decreased by 0.35 copies/16S rRNA after 30 days of storage, but increased the abundance of some ARG subtypes, including tetM, tetX, tetQ, tetS, ermF and sul2. High-concerned ARGs, including NDM-1, mcr-1 and vancomycin resistance genes (including vanA, vanB, vanRA and vanSA), were found in biogas digestate, and NDM-1 and vanB were also detected in aerosols. These results indicated a potential risk of ARGs dispersion during biogas digestate storage. Further research on the dispersion of ARGs from biogas digestate is required to elucidate the emission mechanism and develop mitigation measures.

This study proposed a kind of optimization design for a reversible axial-flow pump based on an ordinary one-way pump. Three-dimensional (3D) Reynolds-averaged Navier&ndash, Stokes (RANS) equations was used to predict the pump performance, and the optimized design was validated by an external characteristic test. Six main geometry parameters of an impeller and diffuser based on an orthogonal experiment were set as design variables. The efficiency and head under forward and reverse design conditions were set as the optimization objective. Based on 120 groups of sample designs obtained from Latin hypercube sampling (LHS), a two-layer artificial neural network (ANN) was used to build a non-linear function with high accuracy between the design variables and optimization objective. The optimized design was obtained from 300 groups of Pareto-optimal solutions using the non-dominated based genetic algorithm (NSGA) for multiobjective optimization. After optimization, there was a slight decrease in the forward pump efficiency and head. The reverse pump efficiency and head on the other hand was largely improved and the high efficiency range was also widened.

Cycling tourism has grown in popularity worldwide, motivating its inclusion in the development strategies of tourism organizations. This paper builds an analysis model based on spatial analysis and Empirical Mode Decomposition, providing a data-driven way to utilize GPS cycling trajectory data to analyze the spatiotemporal behavior of Chinese cycling tourists using a case study example of the Tibet Autonomous Region. The results show that: (1) The fluctuation of the number of cycling trajectories in Tibet presents multi-modal characteristics, corresponding to fluctuations in China's tourism industry and economy; (2) Cycling tourists in Tibet prefer to use national roads (arguably due to the safety of the road infrastructure and the availability of supporting tourism infrastructure); (3) Cycling tourism is highly concentrated in and around the popular attractions of Tibet. The presented data and methods help to understand the spatiotemporal behavior of cycling tourists, which is of great significance for tourism management.

Bioaerosols have important impacts on many scientific fields, including atmospheric environment, ecology, climate change, food safety, anti-bioterrorism, infectious diseases, public health and environmental health. This review was carried out based on the scientific outcomes from the 600th Xiangshan Science Conference held in Beijing, for whcih 47 scientists including those overseas were invited to discuss the bioaerosol research progress. Over the past 10 years, great strides have been made in the bioaerosol field, such as the expansion of research directions, research broadness and also scientists. For example, atmospheric chemistry researchers have also started to carry out studies about bioaerosol impacts on the atmospheric environment, including those on the cloud droplets, the climate and bioaerosol dynamics during haze events. In addition, new methods and instruments for bioaerosol studies are increasingly being developed in bioaerosol monitoring and capture systems, various biosensors, microfluidics, high-throughput sequencing, and they have helped the scientific community obtain a better understanding of microbes in the air. In terms of health effects, human and indoor bioaerosol emissions have become one of the hot research areas. In addition, bioaerosols were also shown to directly affect the oxidation potential of atmospheric particles and thus on the human health, however, the relevant mechanisms remain to be very limited and could be far more complex than what we have known so far. On the other hand, respiratory infections/outbreaks, caused largely by the spread of bioaerosols, continue to be a major killer for humans, especially for younger children. Currently, although a significant progress has been made in high-throughput screening of respiratory pathogens, the airborne disease transmission mechanisms are still not well understood, including the influences on the pathogen viability and effective transmission distance. The risk of military conflicts in certain regions is increasing, which could potentially lead to possible use of biological weapons via bioaerosol for mass human destruction. In addition, the airborne transmission of antibiotic resistant genes has also received wide attention as an emerging biological pollutant. By integrating sampling, microfluidics, biosensors and electronics, the scientists have taken an important step towards real-time online bioaerosol screening and biological hazard early warning. As a special type of bioaerosol, biomarkers in exhaled breath are also increasingly being studied for early disease diagnosis and screening. At the same time, surgical and nosocomial infections caused by the spread of bioaerosols in the hospital settings are also receiving wide attention. The scientific researchers have also made significant advances in the controlling airborne biological agents, e.g., microwave irradiation, cold plasma and nanomaterial filtration. This review intends to broadly review current state-of-the-art advances in bioaerosol studies, to summarize and discuss the existing problems, correspondingly providing references for the future studies. Despite of great progress made in many aspects of bioaerosols, our understanding of its significance and relevant impacts on our surroundings and health is still quite limited. In the years to come, bioaerosol research is expected to turn a new chapter if multidisciplinary collaboration can be further strengthened.

Exposure to indoor airborne microbiomes (bioaerosols) is closely associated with human health. However, knowledge regarding the characteristics of indoor bioaerosols in areas affected by serious ambient air pollution is still limited. In this study, indoor bioaerosols were characterized in winter Beijing via quantitative polymerase chain reaction (qPCR) and amplicon sequencing, and compared to outdoor bioaerosols. Concentrations of indoor bioaerosol were significantly lower than those of the adjacent outdoor bioaerosol, and were not significantly affected by outdoor air pollution. Community structures of indoor bioaerosol were distinct from those of outdoor environment, and were differentially affected by ambient air pollution. Specifically, significant change was observed in indoor fungal community impacted by hazy air pollution, while not in bacteria and archaea. Compared to outdoor air, indoor air was preferentially enriched with fungi (~10%) in winter. Besides, about 40% of the bacteria indoors were likely contributed by outdoor bacteria. The results provide useful information regarding the impact of ambient air pollution on indoor bioaerosols, and furtherly highlight the distinction between indoor and outdoor bioaerosol assemblies.

In this work, we have succeeded in obtaining high quality warm w-LEDs by adopting hybrid two-dimensional (2D) structure of SiNx photonic crystal layer (PCL) assisted cyan-emitting ceramic-plate thiosilicate SrLa2Si2S8:Ce3+ with red-emitting film SrLiAl3N4:Eu2+ phosphor on a 430 nm blue LED chip at 350 mA. 2D SiNx PCL was capped with thiosilicate is because it can enhance the luminous efficacy and maintain the low correlated color temperature (CCT) and high color-rendering index (CRI). High luminous efficacy (82.3 lm/W), high special CRI (R9 = 75) as well as the low CCT (5431 K) of the optimal w-LED was obtained due to the assistances of 2D SiNx PCL and narrow-band red-emitting phosphor with the doping percentage at 10 wt%. The synthesis processes, structural analysis, optical properties and LED device performances were detailed investigated to find out the relationship between the optimum composition and good optical properties. Based on intriguing luminescence properties by the 2D SiNx PCL and red-emitting film phosphor introducing, we proclaim this method could also have high potential application in other phosphor-converted w-LEDs. This article is protected by copyright. All rights reserved.

This study aimed at studying the collection efficiencies of the widely used SKC BioSampler when sampling size-resolved biological viable aerosol particles using an Ultraviolet Aerodynamic Particle Sizer (UV-APS) unit. The test bioaerosols include aerosolized bacterial species and those from indoor air. For optimal performance, different flow rates (Q sampl ) (5, 12.5 and 20 L/min) and different volumes of collection liquids (V cl ) (5, 10 and 20 mL) were tested for bioaerosol particles from 0.5 to 10 µm. In addition, the DNA stain method-the LIVE/DEAD BacLight dye and culturing were also utilized to confirm the viable bioaerosol collection efficiencies of the BioSampler. Experimental data showed that when sampling aerosolized Bacillus subtilis at the flow rate of 12.5 L/min, the collection efficiency of the BioSampler decreased from 82.7% (at V cl =20 mL) to 24.8% (at V cl =5 mL). The results from the BacLight dye and culturing performed for the samples collected by the BioSampler achieved similar conclusions. When sampling indoor air particles, the overall collection efficiencies of all viable biological particles were 95.3%, 87.7% and 65.5%, respectively, for V cl =20 mL, 10 mL and 5 mL at the flow rate of 12.5 L/min. When Q sampl was 20 L/min, the BioSampler performed better with V cl = 5 mL than other volumes. The results from this work suggest that the sampling flow rate plays a dominant role in the overall physical collection efficiency while the collection volume is crucial in preserving the viability of bioaerosol particles. Different from general practice, the operating parameters for the BioSampler should thus be adjusted respectively for target viral, bacterial and fungal aerosol particles.

Livestock manure is one of the major sources of volatile organic compound (VOC) emissions, however, characteristics of VOCs emitted from biogas digestate (BD) storage, which is a common manure practice, remain unclear. The objective of this study was to characterize VOC emissions during BD storage through the dynamic emission vessel method, to identify the VOC emissions that have potential odor and/or toxic effects. The results revealed the detection of 49 VOCs with seven classes, whose total concentration varied from 171.35 to 523.71 &mu, g m&minus, 3. The key classes of the 49 VOCs included Oxygenated VOCs (OVOCs), olefins and halogenated hydrocarbons. The top four compositions, accounting for 74.38% of total VOCs (TVOCs), included ethanol, propylene, acetone and 2-butanone. The top four odorous VOCs, accounting for only 5.15% of the TVOCs, were toluene, carbon disulfide, ethyl acetate and methyl sulfide, with the concentration ranging from 13.25 to 18.06 &mu, 3. Finally, 11 main hazardous air pollutant VOCs, accounting for 32.77% of the TVOCs, were propylene, 2-butanone, toluene, methyl methacrylate, etc., with the concentration ranging from 81.05 to 116.96 &mu, 3. Results could contribute to filling the knowledge gaps in the characteristics of VOC emissions from biogas digestate (BD), and provide a basis for exploring mitigation strategies on odor and hazardous air pollutions.

Maritime traffic can reflect the diverse and complex relations between countries and regions, such as economic trade and geopolitics. Based on the AIS (Automatic Identification System) trajectory data of ships, this study constructs the Maritime Silk Road traffic network. In this study, we used a complex network theory along with social network analysis and network flow analysis to analyze the spatial distribution characteristics of maritime traffic flow of the Maritime Silk Road, further, we empirically demonstrate the traffic inequality in the route. On this basis, we explore the role of the country in the maritime traffic system and the resulting traffic relations. There are three main results of this study. (1) The inequality in the maritime traffic of the Maritime Silk Road has led to obvious regional differences. Europe, west Asia, northeast Asia, and southeast Asia are the dominant regions of the Maritime Silk Road. (2) Different countries play different maritime traffic roles. Italy, Singapore, and China are the core countries in the maritime traffic network of the Maritime Silk Road, Greece, Turkey, Cyprus, Lebanon, and Israel have built a structure of maritime traffic flow in the eastern Mediterranean Sea, and Saudi Arabia serves as a bridge for maritime trade between Asia and Europe. (3) The maritime traffic relations show the characteristics of regionalization, countries in west Asia and the European Mediterranean region are clearly polarized, and competition&ndash, synergy relations have become the main form of maritime traffic relations among the countries in the dominant regions. Our results can provide a scientific reference for the coordinated development of regional shipping, improvement of maritime competition, cooperation strategies for countries, and adjustments in the organizational structure of ports along the Maritime Silk Road.

Spatial patterns of tourist flows represent the movement of tourists and show differences in tourism resources giving advice for promoting balanced and sustainable tourism development. This paper proposes a novel framework for analyzing these patterns based on tourists' digital footprint data collected from online travel diaries. Based on illustrative case study data from Qingdao (China), the framework, combining traditional quantitative and social network analysis, is able to pinpoint: (1) The influence of distance decay and attractions’ popularity on the spatial patterns of tourist flows; (2) The uneven distribution of the core tourist nodes and the existence of the structural hole phenomenon, which form a network pattern with unbalanced power and intense internal competition; (3) The formation of the core area for tourism along the coastline – as is typical for coastal tourism cities. This difference of tourism resources between coastal and inland areas, thus, remains a challenge for future tourism development in Qingdao.

Here, an integrated microfluidic electrostatic sampler (IMES) was designed and evaluated, consisting of a unipolar charging chamber, a half cylinder precipitation electrode and a collection chip for automated air sample delivery. The collection chip includes a half-open microchannel covered with a hydrophobic mesh and a peristaltic micropump. Airborne particles were first charged in the charging chamber and then precipitated into the half-open microchannel by the electrostatic field. After sampling, the integrated micropump automatically delivered the collection liquid through the half-open microchannel to the liquid outlet, washing away those deposited particles into collection reservoir. The maximum allowable velocity in the half-open microchannel was higher than 200 mm/s which is well above the normal operating speed of sample delivery, thus water transportation was quite stable in use. The collection efficiencies of airborne particles and bio-particles were investigated for the sampler. The tested maximum sampling flow rate was 13.2 L/min and the corresponding maximum effective collection efficiency was about 40% for particles smaller than 5 μm at charging voltage of −1.8 kV and collecting voltage of −7 kV. The preliminary experiments showed that the collection efficiencies of bio-particles were about 16% with aerosolized Bacillus subtilis . The lower collection efficiency of bio-particles was partially due to the particle loss on the hydrophobic mesh. Taking into consideration its compact size and integrated function of charging and automatic liquid sample delivery, the IMES is a bioaerosol sampling system ready for integration with subsequent automated detection equipment.

Geo-located travel blogs, a new data source, enable to achieve more detailed analysis of tourists' spatio-temporal behavior. Taking Chinese tourists in Nordic countries as the research object, this paper focuses on their behavior, seasonal patterns and complex network effects by using geo-located travel blog data collected from Qunar.com. The results show that: (1) Chinese tourists visiting Nordic countries are often experienced in traveling. The local climate during the cold season does not prevent them from pursuing the aurora scenery. (2) The travel behavior of Chinese tourists is spatially heterogeneous. The network analysis reveals that Iceland showcases stronger, compared to the other Nordic countries, community independence and small world effect. (3) During the warm season, Chinese tourists choose a variety of destinations, while in cold season, they tend to choose destinations with higher chances for spotting the northern lights. These results provide helpful information for the tourism management departments of Nordic countries to improve their marketing and development efforts directed for Chinese tourists., Highlights • Focus is laid on the behavior of Chinese tourists in Nordic countries. • Complex network theory is introduced to explore the flow patterns of tourists. • Scale-free and small world effects are observed in the tourist flow network. • There is no obvious tourism off-season in Nordic countries due to “aurora chasers”.

Stand-alone portable air purifiers (APs) have become an increasingly popular method of controlling individual inhalation exposure. Exposure to bacterial endotoxins has a causative role in respiratory inhalation health. Here, we studied the changes in endotoxin levels in indoor air before and after purification by a portable AP equipped with HEPA (high-efficiency particulate air) filters. An increase in endotoxins was observed when a previously used AP was turned on to clean the air. Replacing the HEPA filters in the AP helped to mitigate the increase in endotoxins of larger sizes but not endotoxins of smaller sizes. Consequently, the use of APs could lead to increased endotoxin deposition in airways, especially in the alveolar region. The endotoxin concentrations on the HEPA filters were well correlated with the free DNA concentrations on the HEPA filters. This correlation indicates that the disrupted bacteria, which released free DNA, could also release endotoxins, thus making HEPA filters a source of indoor airborne endotoxins. Our results illustrate a potential endotoxin inhalation risk associated with HEPA-APs as an air cleaning strategy and highlight the importance of composition-specific air cleaning while reducing the particle number/mass.