Health effect assessments based on natural killer (NK) cells are an important emerging area of human health. We recruited 90 forest staff members in Xitou, Taiwan and 110 urban staff members in Taipei to investigate the health effects of forest environment exposure on NK cells (CD3−/CD56+) and activating NK cells (CD3−/CD56+/CD69+) in humans. We also invited 11 middle-aged volunteers in a pilot study to participate in a five-day/four-night forest trip to Xitou forest to investigate the health effects of a forest trip on NK cells and activating NK cells. Results showed that NK cells were higher in the forest group (19.5 ± 9.1%) than in the urban group (16.4 ± 8.4%). In particular, the percentage of NK cells was significantly higher in the forest group than in the urban group among the subgroups of male, a higher body mass index (≥ 25 kg/m2), without hypertension, lower high-sensitivity C-reactive protein, hyperglycemia, without smoking habit, and with tea drinking habit. After the five-day trip in Xitou forest, the percentage of activating NK cells of the invited participants from Taipei increased significantly after the trip to Xitou forest (0.83 ± 0.39% vs. 1.72 ± 0.1%). The percentage of activating NK cells was 1.13 ± 0.43%, which was higher than the baseline value of 0.77 ± 0.38% before the forest trip among the seven subjects who participated in the follow-up study four days after returning to Taipei. This study suggests that exposure to forest environments might enhance the immune response of NK cells and activating NK cells in humans.
Environmental nanoparticles exist in the hydrosphere, pedosphere, biosphere, and atmosphere. Their biogeochemical and ecological impacts are some of the fastest growing areas of research today. However, efficient separation of environmental nanoparticles remains difficult. The objective of this study was to develop an automated ultrafiltration device (AUD) for efficient collection of environmental nanoparticles. The AUD utilizes an automated hydraulic ram to facilitate collection of nanoparticles using the ultrafiltration membrane with pore size in the range of 1 to 100 nm. Zeolite A was used as a model nanoparticle sample to demonstrate the efficiency of the AUD. The size distribution and mean particle sizes determined by zeta‐sizer analysis on the collected nanoparticles and their transmission electron micrographs indicated the adequacy of the AUD developed in this study in collecting nanoparticles (1–100 nm). Because of its ability to reduce the time needed for sample collection, coupled with the quantity of nanoparticles collected, the AUD was far more efficient than the conventional syringe method for collecting nanoparticles. The AUD has the characteristics of automation, easy operation, and high efficiency in the separation of nanoparticles and would, thus, facilitate future research and developments in environmental nanoscience and nanotechnology and their impacts on the ecosystem.
The biogeochemical and ecological impacts of environmental nanoparticles (ENPs) are some of the fastest growing areas of research today. However, efficient separation and collection of ENPs in natural systems remains difficult. This review article is focused on experimental investigation of separation and identification of ENPs, including nanoparticles with size fractions in the range of <2000, 450 to 2000, 100 to 450 and 1 to 100 nm. An automated ultrafiltration device (AUD) was used successfully to overcome the problem of efficiently collecting ENPs in large quantities in red soils. A significant amount of hematite nanoparticles was present on the surface coating of kaolinite nanoparticles and aggregated hematite nanoparticles overlapping the edge of a kaolinite flake in a size range of 5 to 8 nm. Synchrotron XRD technique is more straightforward and powerful than conventional XRD with oriented specimens and random powder methods for identifying nanoparticles, crystallinity, and particle size in red soils, particularly for the illite, kaolinite, goethite and hematite nanoparticles. The AUD apparatus can be employed to efficiently collect large quantities of soil and related ENPs for investigation of their structural characteristics and surface properties, which have significant impact on weathering reaction pathways, catalysis, the fate of vital elements and environmental pollutants, and ecosystem restoration.
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