Na 3 V 2Àx Mg x (PO 4 ) 3 /C composites with different Mg 2+ doping contents (x ¼ 0, 0.01, 0.03, 0.05, 0.07 and 0.1) were prepared by a facile sol-gel method. The doping effects on the crystal structure were investigated by XRD, XPS and EXAFS. The results show that low dose doping of Mg 2+ does not alter the structure of the material, and magnesium is successfully substituted for the vanadium site. The Mg doped Na 3 V 2Àx Mg x (PO 4 ) 3 /C composites exhibit significant improvements on the electrochemical performance in terms of the rate capability and cycle performance, especially for the Na 3 V 1.95 Mg 0.05 (PO 4 ) 3 /C. For example, when the current density increased from 1 C to 30 C, the specific capacity only decreased from 112.5 mA h g À1 to 94.2 mA h g À1 showing very good rate capability. Moreover, even cycling at a high rate of 20 C, an excellent capacity retention of 81% is maintained from the initial value of 106.4 mA h g À1 to 86.2 mA h g À1 at the 50th cycle. Enhanced rate capability and cycle performance can be attributed to the optimized particle size, structural stability and enhanced ionic and electronic conductivity induced by Mg doping.batteries for large-scale energy storage system applications is very important. 7 Recently, sodium ion batteries have gained an increasing amount of attention due to their abundant reserves and relatively even geological distribution. 8 Actually, many electrode materials such as Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), 9 Na[Ni 0.25 Fe 0.5 Mn 0.25 ]O 2 / C, 10 Na[Li 0.05 (Ni 0.25 Fe 0.25 Mn 0.5 ) 0.95 ]O 2 , 11 Na x CoO 2 , 12 Na 2 C 8 H 4 O 4 , 13 Na 3 (VO 1Àx PO 4 ) 2 F 1+2x , 14 Prussian blue analogues, 15,16 phosphorus, 17,18 and TiO 2 19 have been studied as active materials in cathodes and anodes for sodium ion batteries. However, due to the bigger ionic radius of the sodium ion than the lithium ion (1.02Å for Na + vs. 0.76Å for Li + ), its storage performance and cycle performance are much poorer than its lithium counterpart. The larger Na + radius is proved to be a crucial obstacle for Na + diffusion. 20,21 Therefore, improving Na + diffusion is quite important in developing new electrode materials for sodium-ion batteries with good electrochemical performance.NASICON-type Na 3 V 2 (PO 4 ) 3 has recently been investigated as a prospective cathode material for sodium ion batteries. It is worth noting that Na 3 V 2 (PO 4 ) 3 possesses the highly covalent three dimensional framework that generates large interstitial spaces through which sodium ions may diffuse easily. [22][23][24][25][26][27] In addition, the electrochemical response of the Na 3 V 2 (PO 4 ) 3 electrode displays two at plateaus at 3.4 V and 1.6 V vs. Na + /Na; the voltage plateau located at 3.4 V is relatively higher than most other cathode materials for sodium ion batteries in recent reports. 28,29 However, Na 3 V 2 (PO 4 ) 3 also has an inherent deciency. The distorted VO 6 octahedral units in the NASICON † Electronic supplementary information (ESI) available: SEM images of Na 3 V 2Àx Mg x (PO 4 ) ...

The timing of flowering is pivotal for maximizing reproductive success under fluctuating environmental conditions. Flowering time is tightly controlled by complex genetic networks that integrate endogenous and exogenous cues, such as light, temperature, photoperiod, and hormones. Here, we show that AGAMOUS-LIKE16 (AGL16) and its negative regulator microRNA824 (miR824) control flowering time in Arabidopsis thaliana. Knockout of AGL16 effectively accelerates flowering in nonvernalized Col-FRI, in which the floral inhibitor FLOWERING LOCUS C (FLC) is strongly expressed, but shows no effect if plants are vernalized or grown in short days. Alteration of AGL16 expression levels by manipulating miR824 abundance influences the timing of flowering quantitatively, depending on the expression level and number of functional FLC alleles. The effect of AGL16 is fully dependent on the presence of FLOWERING LOCUS T (FT). Further experiments show that AGL16 can interact directly with SHORT VEGETATIVE PHASE and indirectly with FLC, two proteins that form a complex to repress expression of FT. Our data reveal that miR824 and AGL16 modulate the extent of flowering time repression in a long-day photoperiod.

FLOWERING LOCUS T (FT) regulates the floral transition in many plant species by integrating environmental seasonal signals and internal cues. Here we show that two interdependent regulatory regions are necessary and sufficient to convey photoperiod responsiveness to FT. While a minimal distance between the regulatory regions is required to fully suppress FT expression under short days, increased distance reduces promoter response to long days. Natural variation at FT creating promoter length differences is widespread, correlates with longitudinal and latitudinal clines and affects a promoter region physically interacting with both photoperiod control regions. Three major FT promoter variants correlate with differences in FT allele usage in F1 hybrids. We propose that FT variation in cis could be adaptive by conferring differences in FT transcriptional control ultimately translating to increased fitness.