Polyimide@Ketjenblack Composite: A Porous Organic Cathode for Fast Rechargeable Potassium-Ion Batteries

Potassium‐ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium‐ion batteries. Here, a porous organic Polyimide@Ketjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g^{-1} at 100 mA g^{-1}), high rate capability (125 and 105 mAh g^{-1} at 1000 and 5000 mA g^{-1}), and long cycling stability (76% capacity retention at 2000 mA g^{-1} over 1000 cycles). The domination of fast capacitive‐like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization. Moreover, a renewable and low‐cost full cell is demonstrated with superior rate behavior (106 mAh g^{-1} at 3200 mA g^{-1}). This work proposes a strategy to design polymer electrodes for high‐performance organic PIBs

Autoregulation of the Drosophila Noncoding roX1 RNA Gene

Most genes along the male single X chromosome in Drosophila are hypertranscribed about two-fold relative to each of the two female X chromosomes. This is accomplished by the MSL (male-specific lethal) complex that acetylates histone H4 at lysine 16. The MSL complex contains two large noncoding RNAs, roX1 (RNA on X) and roX2, that help target chromatin modifying enzymes to the X. The roX RNAs are functionally redundant but differ in size, sequence, and transcriptional control. We wanted to find out how roX1 production is regulated. Ectopic DC can be induced in wild-type (roX1+ roX2+) females if we provide a heterologous source of MSL2. However, in the absence of roX2, we found that roX1 expression failed to come on reliably. Using an in situ hybridization probe that is specific only to endogenous roX1, we found that expression was restored if we introduced either roX2 or a truncated but functional version of roX1. This shows that pre-existing roX RNA is required to positively autoregulate roX1 expression. We also observed massive cis spreading of the MSL complex from the site of roX1 transcription at its endogenous location on the X chromosome. We propose that retention of newly assembled MSL complex around the roX gene is needed to drive sustained transcription and that spreading into flanking chromatin contributes to the X chromosome targeting specificity. Finally, we found that the gene encoding the key male-limited protein subunit, msl2, is transcribed predominantly during DNA replication. This suggests that new MSL complex is made as the chromatin template doubles. We offer a model describing how the production of roX1 and msl2, two key components of the MSL complex, are coordinated to meet the dosage compensation demands of the male cell

Boromullite, Al9BSi2O19, a new mineral from granulite-facies metapelites, Mount Stafford, central Australia: a natural analogue of a synthetic "boron-mullite"

Boromullite is a new mineral corresponding to a 1:1 polysome composed of Al5BO9 and Al2SiO5 modules. Electron-microprobe analysis of the holotype prism is SiO2 19.01(l.12), TiO2 0.01(0.02), B2O3 6.52(0.75), Al2O3 74.10(0.95), MgO 0.07(0.03), CaO 0.00(0.02), MnO 0.01(0.04), FeO 0.40(0.08), Sum 100.12 wt.%, which gives Mg0.01 Fe0.03 Al8.88 Si1.93 B1.14 O18.94 (normalised to 12 cations), ideally Al9BSi2O19. Overall, in the type specimen, it ranges in composition from Mg0.01 Fe0.03 Al8.72 Si2.44 B0.80 O19.20 to Mg0.01 Fe0.03 Al9.22 Si1.38 B1.35 O18.67. Single-crystal X-ray diffraction gives orthorhombic symmetry, Cmc21, a 5.7168(19) Å, b 15.023(5) Å, c 7.675(3) Å, V 659.2(7) Å3, calculated density 3.081 g/cm3, Z = 2. The refined structure model indicates two superimposed modules present in equal proportions in the holotype prism. Module 1 has the topology and stoichiometry of sillimanite and carries all the Si, whereas module 2 is a type of mullite defect structure in which Si is replaced by B in triangular coordination and by Al in tetrahedral coordination, i.e., Al5BO9. The strongest lines in the powder pattern [d in Å, Imeas.), (hkl)] are 5.37(50) (021), 3.38(100) (022, 041), 2.67 (60) (042), 2.51(60) (221, 023), 2.19(80) (222), 2.11(50) (043), 1.512(90) (263). Boromullite is colourless and transparent, biaxial (+), nx 1.627(1), ny 1.634(1), nz 1.649(1) (589 nm). 2Vz (meas) = 57(2)°, 2Vz (calc) = 69(12)°. In the type specimen boromullite tends to form prisms or bundles of prisms up to 0.4 mm long, typically as fringes or overgrowths on aggregates of sillimanite or as narrow overgrowths around embayed werdingite prisms. In other samples boromullite and sillimanite are intergrown on a fine scale (from 10 μm). Sekaninaite-cordierite, potassium feldspar, biotite, werdingite and its Fe-dominant analogue, hercynite, and ilmenite are other commonly associated minerals, whereas ominelite-grandidierite, plagioclase, andalusite, and tourmaline are much subordinate. The most widespread accessories are monazite-(Ce), an apatite-group mineral and zircon. Boromullite formed during anatexis of B-rich pelitic rocks under granulite facies conditions (810 °C ≈ T ≥ 775-785 °C, P = 3.3-4 kbar), possibly due to a shift in bulk composition to lower SiO2 and B2O3 contents associated with melt extraction. The assemblage boromullite + cordierite + sillimanite lies at lower SiO2 and B2O3 contents than the assemblage werdingite + cordierite + sillimanite and thus a decrease in SiO2 and B2O3 leads to the replacement of werdingite by boromullite, consistent with textural relations

A Sodium Polysulfide Battery with Liquid Solid Electrolyte Improving Sulfur Utilization Using P2S5 as Additive and Tetramethylurea as Catholyte Solvent

Herein, the proof of concept of a sodium polysulfide battery consisting of two electrode chambers being separated by a solid electrolyte is described. The concept is suited for dissolved polysulfide cathodes and has the advantage that both half reactions can be optimized separately. The formation of solid sulfide discharge products is identified as the major limiting factor for cell cycling. This issue can be alleviated by adding solid P2S5. Further improvement can be achieved by replacing diglyme 2G as the cathode compartment solvent with tetramethylurea TMU . Using TMU, the cell cycles with Coulombic efficiencies gt;99 and capacities of 800 amp; 8201;mAh amp; 8201;g amp; 8722;1 are maintained for at least 30 cycles. Viscosity, density, conductivity, and the electrochemical stability window values of the 2G amp; 8208; and TMU amp; 8208;based electrolytes are compared. The latter shows higher viscosity 2.806 vs 1.603 amp; 8201;mPa amp; 8201;s , higher density 1.016 vs 0.996 amp; 8201;g amp; 8201;cc amp; 8722;1 , and higher conductivity 4.27 vs 1.45 amp; 8201;mS amp; 8201;cm amp; 8722;1 . The oxidative stability limit of the TMU electrolyte is 3.2 amp; 8201;V versus Na Na, which is sufficient for polysulfide redox reactions. Vis spectroscopy is used to follow the electrode reaction. In case of TMU, the reaction is based on the redox activity of S3 amp; 8722; radicals blue coloration of the catholyte solutio

Correction to Comparison of in Situ and ex Situ methods for synthesis of two-photon polymerization polymer nanocomposites [Polymers, 6, (2014) 2037-2050]

[No abstract available