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In this paper, we develop a numerical model based on a multiphasic theory to simulate the deformation response of a hydrogel strip immersed into an acidic solution under an external electric field. The deformation response consists of complicated mechano-electrochemical behaviours including mechanical effects (pressure and diffusive drag), chemical effects (concentration, chemical potential, osmotic pressure) and electric effects (electric field intensity, electric potential). The complexly coupled nonlinear governing equations are numerically solved using a recently developed meshless radial basis function method. We analyse the major factors which influence the swelling/shrinking behaviours of the hydrogel strip. The numerical results show good agreement with the experimental

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This paper studied the piezoresistive effects of cementitious composites filled with nano graphite platelets (NGPs). Experiments are performed to investigate the electrical responses of cementitious composites filled with NGPs when subjected to cyclic compressive stress under different quasi static and dynamic loading conditions such as different loading amplitudes, different loading rates and constant loading within the elastic regime of these composites. Meanwhile, the cementitious composites filled with NGPs are explored for the application in measuring dynamical loading rate. The results demonstrated that cementitious composites filled with NGPs possess sensitive piezoresistive effect and stable repeatability to different loading conditions.

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Rice is a major dietary source of the toxic metalloid arsenic. Reducing arsenic accumulation in rice grain is important for food safety. We generated transgenic rice overexpressing two aquaporin genes, OsNIP1;1 and OsNIP3;3, under the control of a maize ubiquitin promoter or the rice OsLsi1 promoter, and tested the effect on arsenite uptake and translocation. OsNIP1;1 and OsNIP3;3 were highly permeable to arsenite in Xenopus oocyte assays. Both transporters were localized at the plasma membrane. Knockout of either gene had little effect on arsenite uptake or translocation. Overexpression of OsNIP1;1 or OsNIP3;3 in rice did not affect arsenite uptake but decreased root-to-shoot translocation of arsenite and shoot arsenic concentration markedly. The overexpressed OsNIP1;1 and OsNIP3;3 proteins were localized in all root cells without polarity. Expression of OsNIP1;1 driven by the OsLsi1 promoter produced similar effects. When grown in two arsenic-contaminated paddy soils, overexpressing lines contained significantly lower arsenic concentration in rice grain than the wild-type without compromising plant growth or the accumulation of essential nutrients. Overexpression of OsNIP1;1 or OsNIP3;3 provides a route for arsenite to leak out of the stele, thus restricting arsenite loading into the xylem. This strategy is effective in reducing arsenic accumulation in rice grain.

Previous studies have shown that the Nodulin 26-like intrinsic membrane protein (NIP) Lsi1 (OsNIP2;1) is involved in arsenite [As(III)] uptake in rice (Oryza sativa). However, the role of other rice NIPs in As(III) accumulation in planta remains unknown. In the present study, we investigated the role OsNIP3;2 in As(III) uptake in rice. When expressed in Xenopus laevis oocytes, OsNIP3;2 showed a high transport activity for As(III). Quantitative real-time RT-PCR showed that the expression of OsNIP3;2 was suppressed by 5 µM As(III), but enhanced by 20 and 100 µM As(III). Transgenic rice plants expressing OsNIP3;2pro-GUS showed that the gene was predominantly expressed in the lateral roots and the stele region of the primary roots. Transient expression of OsNIP3;2:GFP fusion protein in rice protoplasts showed that the protein was localized in the plasma membrane. Knockout of OsNIP3;2 significantly decreased As concentration in the roots, but had little effect on shoot As concentration. Synchrotron microfocus X-ray fluorescence showed decreased As accumulation in the stele of the lateral roots in the mutants compared with wild-type. Our results indicate that OsNIP3;2 is involved in As(III) uptake by lateral roots, but its contribution to As accumulation in the shoots is limited.