A general numerical model of leukocyte adhesion in microchannels.

Leukocyte adhesion on the vascular endothelium plays an important role in human immune system and reflects the physiological condition of a human body. In this paper, a generally implementable dynamic adhesion model based on the length limit of microvilli was developed to explore the behavior of a suspended leukocyte's adhesion process under microchannel shear flow. Simulations showed that the whole adhesion process can be divided into cell sedimentation, preliminary adhesion and stable dynamic adhesion stages. The cell tumbling kinetics, cell deformation, cell adhesion area and adhesion force were studied under the conditions of various bond strength, cell membrane surface tension, inlet flow velocity and cytoplasmic viscosity. Results showed that the bond strength affects the cell tumbling behaviors differently by changing the adhesion force. The cell with lower membrane surface tension induces a larger adhesion area, and eventually results in a greater adhesion and a lower cell tumbling velocity. The flow velocity changes cell velocity through the flow viscous force during the whole adhesion process. The cytoplasmic viscosity affects adhesion mainly in the preliminary adhesion stage by changing the cell deformation rate but has slight effect on the stabilized dynamic adhesion on cells. This study provides a simple theoretical basis to further clarify the mechanism of cell behaviors under stress and adhesion and becomes one of the prerequisites for study of tissue inflammation, wound healing, and disease treatments.

Insight into the interaction between Fe-based nanomaterials and maize (Zea mays) plants at metabolic level.

Properly understanding the fundamental interactions between engineered nanoparticles (NPs) and plants is crucial for nano-enabled agriculture. In this study, Fe and Fe3O4 (magnetite), which are naturally occurred nanosized crystals and minerals, were foliar applied to 4-week-old maize plants for 10 days to evaluate their impact on plant photosynthesis and growth. Hill reaction of isolated maize leaf chloroplasts was carried out to determine the performance of two Fe-based NPs on photosynthetic activities at cell level. Meanwhile, gas chromatography-mass spectrometry (GC-MS) based metabolomics was used to explore the deep insight into the interaction between Fe-based NPs and maize plants. Results showed that maize leaf net photosynthesis rate and chlorophyll content were significantly increased by Fe NPs for 19.9% and 19.3%; and Fe3O4 NPs for 27.5% and 26.1%, respectively. Accordingly, plant biomass has been significantly increased by Fe and Fe3O4 NPs by 31.8% and 34.6%, respectively. Metabolomics revealed that both Fe-based NPs induced metabolic reprogramming in maize leaves. The biosynthesis of some compatible solutes and antioxidant compounds were inhibited. In addition, exposure to Fe-based NPs tentatively shut down some energy consuming pathways, such as photorespiration, alanine metabolism, branch chain amino acid biosynthesis. The trade-off of energy consuming pathways might be alternative explanation for the enhanced photosynthesis. The results of this study exhibited the promising potential for Fe-based NPs to be used in nano-enabled agriculture to promote plant growth.

Physiological and metabolic responses of maize (Zea mays) plants to Fe3O4 nanoparticles.

Fe3O4 nanoparticles (NPs), as representative magnetic materials, have been widely used in the industrial and biomedical sectors, and their environmental impacts must be evaluated for their sustainable use. In this study, the interactions between Fe3O4 NPs and maize plants were investigated by a combination of phenotypic and metabolic approaches. Maize plants (Zea mays) were grown in soil treated with Fe3O4 NPs at 0, 50 and 500 mg/kg for 4 weeks. Fe3O4 NPs had no impact on plant biomass or photosynthesis. However, root length of maize plant significantly increased, with decreased malondialdehyde (MDA) level, indicating the positive effects on root development and membrane integrity. Inductively coupled plasma optical emission spectrometry (ICP-OES) revealed that Fe3O4 NPs resulted in a significant Fe accumulation in roots, instead of leaves. In addition, 500 mg/kg Fe3O4 NPs significantly promoted dehydrogenase enzyme activity by 84.9%. Metabolomics revealed that maize root metabolomes were re-programmed by Fe3O4 NPs exposure. Metabolic pathways associated with antioxidant and defence were inactivated by Fe3O4 NPs, indicating the protective role of Fe3O4 NPs for microbes and plant roots. Taken together, the results indicate a limited impact of environmental Fe3O4 NPs on plant growth. Taken together, the results of this study offer new insights into the molecular mechanisms by which maize responds to Fe3O4 NP exposure.

Carbonized Tree-Like Furry Magnolia Fruit-Based Evaporator Replicating the Feat of Plant Transpiration.

It has long been an aspirational goal to create artificial evaporators that allow omnidirectional energy absorptance, adequate water supply, and fast vapor transportation, replicating the feat of plant transpiration, to solve the global water crisis. This work reveals that magnolia fruits, as a kind of tree-like living organism, can be outstanding 3D tree-like evaporators through a simple carbonization process. The arterial pumping, branched diffusion, and confined evaporation are achieved by the "trunk," "branches," and "leaves," respectively, of the mini tree. The mini tree possesses omnidirectional high light absorptance with minimized heat loss and gains energy from the environment. Water confined in the fruit possesses reduced vaporization enthalpy and transports quickly following the Murray's law. A record-high vapor generation rate of 1.22 kg m-2 h-1 in dark and 3.15 kg m-2 h-1 under 1 sun illumination is achieved under the assistance of the gully-like furry surface. The "absorption of nutrients" enables the fruit to recover valuable heavy metals as well as to produce clean water from wastewater efficiently. These findings not only reveal the hidden talent of magnolia fruits as cheap materials for vapor generation but also inspire future development of high-performance, full-time, and all-weather vapor generation and water treatment devices.