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Background Metal homeostasis is critical for plant growth, development and adaptation to environmental stresses and largely governed by a variety of metal transporters. The plant ZIP ( Z n-regulated transporter, I ron-regulated transporter-like P rotein) family proteins belong to the integral membrane transporters responsible for uptake and allocation of essential and non-essential metals. However, whether the ZIP family members mediate metal efflux and its regulatory mechanism remains unknown. Results In this report, we provided evidence that OsZIP1 is a metal-detoxified transporter through preventing excess Zn, Cu and Cd accumulation in rice. OsZIP1 is abundantly expressed in roots throughout the life span and sufficiently induced by excess Zn, Cu and Cd but not by Mn and Fe at transcriptional and translational levels. Expression of OsZIP-GFP fusion in rice protoplasts and tobacco leaves shows that OsZIP1 resides in the endoplasmic reticulum (ER) and plasma membrane (PM). The yeast ( Saccharomyces cerevisiae ) complementation test shows that expression of OsZIP1 reduced Zn accumulation. Transgenic rice overexpressing OsZIP1 grew better under excess metal stress but accumulated less of the metals in plants. In contrast, both oszip1 mutant and RNA interference (RNAi) lines accumulated more metal in roots and contributed to metal sensitive phenotypes. These results suggest OsZIP1 is able to function as a metal exporter in rice when Zn, Cu and Cd are excess in environment. We further identified the DNA methylation of histone H3K9me2 of OsZIP1 and found that OsZIP1 locus, whose transcribed regions imbed a 242 bp sequence, is demethylated, suggesting that epigenetic modification is likely associated with OsZIP1 function under Cd stress. Conclusion OsZIP1 is a transporter that is required for detoxification of excess Zn, Cu and Cd in rice.

Background Non-essential trance metal such as cadmium (Cd) is toxic to plants. Although some plants have developed elaborate strategies to deal with absorbed Cd through multiple pathways, the regulatory mechanisms behind the Cd tolerance are not fully understood. Ferrochelatase-1 (FC1, EC4.99.1.1) is the terminal enzyme of heme biosynthesis, catalyzing insertion of ferrous ion into protoporphyrin IX. Recent studies have shown that FC1 is involved in several physiological processes. However, its biological function associated with plant abiotic stress response is poorly understood. Results In this study, we showed that AtFC1 was transcriptionally activated by Cd exposure. AtFC1 overexpression ( 35S::FC1 ) lines accumulated more Cd and non-protein thiol compounds than wild-type, and conferred plant tolerance to Cd stress, with improved primary root elongation, biomass and chlorophyll (Chl) content, and low degree of oxidation associated with reduced H 2 O 2 , O ·2- and peroxides. In contrast, the AtFC1 loss of functional mutant fc1 showed sensitivity to Cd stress. Exogenous provision of heme, the product of AtFC1, partially rescued the Cd-induced toxic phenotype of fc1 mutants by improving the growth of seedlings, generation of glutathione (GSH) and phytochelatins (PCs), and GSH/PCs-synthesized gene expression (e.g. GSH1 , GSH2 , PCS1 , and PCS2 ). To investigate the mechanism leading to the AtFC1 regulating Cd stress response in Arabidopsis, a transcriptome of fc1 mutant plants under Cd stress was profiled. Our data showed that disfunction of AtFC1 led to 913 genes specifically up-regulated and 522 genes down-regulated in fc1 mutants exposed to Cd. Some of the genes are involved in metal transporters, Cd-induced oxidative stress response, and detoxification. Conclusion These results indicate that AtFC1 would act as a positive regulator of plant tolerance to Cd stress. Our study will broaden our understanding of the role of FC1 in mediating plant response to Cd stress and provide a basis for further exploration of its downstream genes.

Ferrochelatase-1 as a terminal enzyme of heme biosynthesis regulates many essential metabolic and physiological processes. Whether FC1 is involved in plant response to salt stress has not been described. This study shows that Arabidopsis overexpressing AtFC1 displays resistance to high salinity, whereas a T-DNA insertion knock-down mutant fc1 was more sensitive to salt stress than wild-type plants. AtFC1 conferred plant salt resistance by reducing Na + concentration, enhancing K + accumulation and preventing lysis of the cell membrane. Such observations were associated with the upregulation of SOS1 , which encodes a plasma membrane Na + /H + antiporter. AtFC1 overexpression led to a reduced expression of several well known salt stress-responsive genes such as NHX1 and AVP1 , suggesting that AtFC1 -regulated low concentration of Na + in plants might not be through the mechanism for Na + sequestration. To investigate the mechanism leading to the role of AtFC1 in mediating salt stress response in plants, a transcriptome of fc1 mutant plants under salt stress was profiled. Our data show that mutation of AtFC1 led to 490 specific genes up-regulated and 380 specific genes down-regulated in fc1 mutants under salt stress. Some of the genes are involved in salt-induced oxidative stress response, monovalent cation-proton (Na + /H + ) exchange, and Na + detoxification.

In order to improve the recovery and utilization rates of sinter waste heat effectively, the organic Rankine cycle (ORC) system with subcritical cycle was designed to recover the low-temperature sinter cooling flue gas waste heat in an annular cooler for power generation. The thermodynamic, economic and multi-objective optimization models of ORC system were established, and R600a was selected as the ORC working medium. Subsequently, the variations in system thermodynamic performance and economic performance with the ORC thermal parameters were discussed in detail, and the optimal ORC thermal parameters were determined. The results show that the system net output power increases with increasing the evaporation temperature and decreasing the condensation temperature and increases first and then, decreases with the increase in superheat degree for a given flue gas outlet temperature in the evaporator, while the heat transfer area per unit net output power appears different variation trends in various ranges of flue gas outlet temperature. Taking the sinter cooling flue gas waste heat of 160 °C as the ORC heat source, the optimal thermal parameters of ORC system were the flue gas outlet temperature of 90 °C, the evaporation temperature of 95 °C, the superheat degree of 10 °C, and the condensation temperature of 28 °C.

The parameter study of sinter waste heat recovery in vertical tank was conducted numerically by using energy and exergy analysis, and the experimental data obtained from a homemade experimental apparatus was applied to verify the reliability of numerical model. Based on the first and second laws of thermodynamics, the effects of flow rate of cooling air (FRCA) and inlet temperature of cooling air (ITCA), as well as the inner diameter of cooling section (IDCS) and height of cooling section (HCS), on the sinter cooling process were analyzed in detail. The results show that the average deviation between the experimental data and calculation values is 4.93%, and the model reliability is verified. The enthalpy exergy of outlet air tends to increase first and then decrease with increasing the FRCA and ITCA, while increasing the IDCS only leads to the increase in enthalpy exergy of outlet air. For a given operational condition, the enthalpy exergy of outlet air can reach a maximum value with increasing the HCS. The vertical tank could obtain the maximum enthalpy exergy of outlet air through the adjustments of FRCA and ITCA, as well as the HCS.

The sinter cooling flue gas expelled from the end of an annular cooler was taken as the heat source of an organic Rankine cycle (ORC) system, and R123, R245fa, R600, R601 and R601a were selected as the working fluids of the ORC system. The effects of evaporation temperature and superheat degree of working fluid, as well as the pinch point temperature difference in the evaporator on the system thermal performance, were analyzed in detail. The results show that the system net output power and exergy efficiency for different working fluids first increase and then decrease with an increase in the evaporation temperature and decrease with an increase in the superheat degree and pinch point temperature difference. The change in pinch point temperature difference has no effect on the system thermal efficiency. For a given operational condition, the system thermal efficiency and exergy efficiency of R123 are the maximum, while the system total irreversible loss of R245fa is the maximum. When the evaporation temperature is greater than 110 °C, the system net output power of R600 is the maximum. The ORC system could obtain the maximum net output power and exergy efficiency through the adjustment of evaporation temperature of working fluid.

Atrazine (ATR) is a pesticide widely used for controlling weeds for crop production. Crop contamination with ATR negatively affects crop growth and development. This study presents the first genome-wide single-base-resolution maps of DNA methylation in ATR-exposed rice. Widespread differences were identified in CG and non-CG methylation marks between the ATR-exposed and ATR-free (control) rice. Most of DNA methyltransferases, histone methyltransferases and DNA demethylase were differentially regulated by ATR. We found more genes hypermethylated than those hypomethylated in the regions of upstream, genebody and downstream under ATR exposure. A stringent group of 674 genes ( p  < 0.05, two-fold change) with a strong preference of differential expression in ATR-exposed rice was identified. Some of the genes were identified in a subset of loss of function mutants defective in DNA methylation/demethylation. Provision of 5-azacytidine (AZA, inhibitor of DNA methylation) promoted the rice growth and reduced ATR content. By UPLC/Q-TOF-MS/MS, 8 degraded products and 9 conjugates of ATR in AZA-treated rice were characterized. Two of them has been newly identified in this study. Our data show that ATR-induced changes in DNA methylation marks are possibly involved in an epigenetic mechanism associated with activation of specific genes responsible for ATR degradation and detoxification.

Spin-lattice (SL) coupling plays an important role in spintronic applications given its effects on magnetic, ferroelectric, optical, and thermodynamic properties. Experiments and theoretical calculations have revealed a large SL coupling effect in CrGeTe 3 and CrI 3 monolayers. However, the microscopic origin of SL coupling in these systems is still unclear. In this work, we develop a systematic method to explore the atomistic mechanism of SL coupling based on the density functional theory. We find that the first- and second-order SL couplings in ternary system CrGeTe 3 are considerably stronger than those in binary system CrI 3 . For the first-order SL coupling, the Cr ions of the magnetic pair and Ge ions positively contribute to the strain enhancement of ferromagnetism in CrGeTe 3 . However, the Cr ions provide a negative contribution in CrI 3 . Furthermore, our tight-binding analysis suggests that the p-d hopping in CrGeTe 3 gradually decreases with the tensile strain, rapidly enhancing the ferromagnetism under the tensile strain. The large frequency shifts in CrGeTe 3 are caused by the large second-order exchange derivatives (one type of second-order SL coupling) of the Cr ions of the magnetic pair.

The results from three methods aimed at improving precipitation type （e.g., rain, sleet, and snow） estimation are presented and compared in this paper. The methods include the threshold air temperature （AT）, threshold wet bulb temperature （WBT） and Koistinen and Saltikoff （KSS） methods. Dot graphs are plotted to acquire the threshold air temperature or the threshold wet bulb temperature using daily averaged air temperature, wet bulb temperature and precipitation data at 643 stations from 1961 to 1979 （precipitation types are not labeled in the database from 1980 to present） in China. The results indicate that the threshold AT or WBT methods are not able to differentiate rain, sleet and snow in the most regions in China; sleet is difficult to differentiate from other precipitation types based on the two threshold methods. Therefore, one threshold AT and WBT method was used in this study to differentiate rain and snow. Based on Gaussian- Kriging interpolation of threshold air temperature （To） and wet bulb temperature （Tw）, the To and Tw contour lines and contour surfaces are calculated for China. Finally, a comparison between the KSS, AT and WBT methods are provided in which the KSS method is calculated based on air temperature and relative humidity. The results suggest that the KSS method is more appropriate for water phase estimation than are the other methods; the maximum precision for rain and snow is 99% and 94%, respectively. The AT method performs better than the WBT method when the critical air temperature is 2℃.

Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras （LTL5210A） were installed around the Hulugou river basin （HRB） in the Qilian Mountains along northeastern margin of the Tibetan Plateau （38°15′54″N, 99°52′53″E） in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.