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Understanding the mechanism by which plants respond to cold stress and strengthen their tolerance to low temperatures is an important and challenging task in plant sciences. Experiments have established that the first step in the perception and transduction of the cold stress signal consists of a transient influx of Ca 2+. This Ca 2+ influx triggers the activation of a cascade of phosphorylation-dephosphorylation reactions that eventually affects the expression of C-repeat-binding factors (CBFs, notably CBF3), which were shown in many plants to control resistance to cold stress by regulating the expression of cold-regulated (COR) genes. Based on experimental observations mostly made on Arabidopsis thaliana, we build a computational model for the cold response pathway in plants, from the transduction of the cold signal via the transient influx of Ca 2+ to the activation of the phosphorylation cascade leading to CBF3 expression. We explore the dynamics of this regulatory network by means of numerical simulations and compare the results with experimental observations on the dynamics of the cold response, both for the wild type and for mutants. The simulations show how, in response to cold stress, a brief Ca 2+ influx, which is over in minutes, is transduced along the successive steps of the network to trigger the expression of cold response genes such as CBF3 within hours. Sometimes, instead of a single Ca 2+ spike the decrease in temperature brings about a train of highfrequency Ca 2+ oscillations. The model is applied to both types of Ca 2+ signaling. We determine the dynamics of the network in response to a series of identical cold stresses, to account for the observation of desensitization and resensitization. The analysis of the model predicts the possibility of an oscillatory expression of CBF3 originating from the negative feedback exerted by ZAT12, a factor itself controlled by CBF3. Finally, we extend the model to incorporate the circadian control of CBF3 expression, to account for the gating of the response to cold stress by the plant circadian clock.

Light‐weight, portability and miniaturization are important characteristics for the next generation of high‐performance electromagnetic interference (EMI) shielding equipment. To meet the current demand for high‐performance EMI shielding materials, this paper proposes a simple and reliable method for preparing multilayer paper‐based composites. Paper‐based composites exhibit light weight, flexibility, easy processing and high temperature resistance. A conductive metal–organic skeleton (Ni‐CAT) layer and polypyrrole (PPy) layer were deposited on a polyimide (PI) fiber surface with an in situ synthesis and gas aggregation method to prepare paper‐based electromagnetic shielding composites with good properties. The results showed that the electromagnetic shielding effect (SE) of the paper‐based composites reached 41.0 dB. After the paper‐based composites underwent multiple ultrasonic washing and bending tests, their electrical conductivity retention rate was as high as 90%. Furthermore, the introduction of PPy/Ni‐CAT enhanced the bonding strength of the PI fibers, which caused the tensile strength of the paper‐based composites to reach 22.3 MPa. Due to the good thermal stability of the composites, they can withstand an open flame and protect the equipment during a fire. Thus, these paper‐based EMI shielding composites hold great promise for flexible electromagnetic shielding materials, protection of smart wearable devices and other fields.

Oscillation is one of the most important phenomena in the chemical reaction systems in living cells. The general purpose simulation algorithms fail to take into account this special character and produce unsatisfying results. In order to enhance the accuracy of the integrator, the second-order derivative is incorporated in the scheme. The oscillatory feature of the solution is captured by the integrators with an exponential fitting property. Three practical exponentially fitted TDRK (EFTDRK) methods are derived. To test the effectiveness of the new EFTDRK methods, the two-gene system with cross-regulation and the circadian oscillation of the period protein in Drosophila are simulated. Each EFTDRK method has the best fitting frequency which minimizes the global error. The numerical results show that the new EFTDRK methods are more accurate and more efficient than their prototype TDRK methods or RK methods of the same order and the traditional exponentially fitted RK method in the literature.

Hydrological models often require calibration. Multi-objective calibration has been more widely used than single-objective calibration. However, it has not been fully ascertained that multi-objective calibration will necessarily guarantee better model accuracy. To test whether multi-calibration was effective in comparison to single-calibration in terms of model accuracy, two strategies were tested out. For these strategies, the objective functions used included the Nash–Sutcliffe efficiency and its logarithmic form, which highlight high flow and low flow, respectively. These two indexes were first used for multi-objective calibration, and then they were separately employed for single-objective calibration. To assess the calibration strategies' accuracy, the simulated streamflow was compared with observed streamflow, particularly high flow and low flow. This study was conducted in the upper stream of the Heihe River basin in northwest China using the FLEX-Topo model and MOSCEM-UA algorithm. The results show that the simulation based on the Nash–Sutcliffe efficiency performed best both in modelling the dynamics and simulating the high flow of the observed streamflow. Thus, it seems that multi-objective calibration does not necessarily lead to better model accuracy. This conclusion might provide useful information for hydrologists in calibrating their models, making their simulations more reliable.