Equilibrium Conditions for Semiclathrate Hydrates Formed with CO₂, N₂, or CH₄ in the Presence of Tri‑<i>n</i>‑butylphosphine Oxide

We measured the thermodynamic stability conditions for the N₂, CO₂, or CH₄ semiclathrate hydrate formed from the aqueous solution of tri-<i>n</i>-butylphosphine oxide (TBPO) at 26 wt %, corresponding to the stoichiometric composition for TBPO·34.5H₂O. The measurements were performed in the temperature range 283.71–300.34 K and pressure range 0.35–19.43 MPa with the use of an isochoric equilibrium step-heating pressure-search method. The results showed that the presence of TBPO made these semiclathrate hydrates much more stable than the corresponding pure N₂, CO₂, and CH₄ hydrates. At a given temperature, the semiclathrate hydrate of 26 wt % TBPO solution + CH₄ was more stable than that of 26 wt % TBPO solution + CO₂, which in turn was more stable than that of 26 wt % TBPO solution + N₂. We analyzed the phase equilibrium data using the Clausius–Clapeyron equation and found that, in the pressure range 0–20 MPa, the mean dissociation enthalpies for the semiclathrate hydrate systems of 26 wt % TBPO solution + N₂, 26 wt % TBPO solution + CO₂, and 26 wt % TBPO solution + CH₄ were 177.75, 206.23, and 159.00 kJ·mol^–1, respectively

Selenium-Doped Sulfurized Polyacrylonitrile Hybrid Cathodes with Ultrahigh Sulfur Content for High-Performance Solid-State Lithium Sulfur Batteries

The solid-state lithium sulfur battery (SSLSB) is an attractive next-generation energy storage system by reason of its remarkably high energy density and safety. However, the SSLSB still faces critical challenges, such as sluggish reaction kinetics, mismatched interface, and undesirable reversible capacity. Herein, a high-performance SSLSB is reported using sulfurized polyacrylonitrile with rich selenium-doped sulfur (Se/S–S@pPAN) as a cathode and poly(ethylene oxide)/Li7La3Zr1.4Ta0.6O12 (PEO-LLZTO) as an electrolyte. The sulfur content of the cathode up to 60.9 wt % can be achieved by dispersing selenium sulfide (SeSx) species in the sulfurized polyacrylonitrile (S@pPAN) skeleton at a molecular level. Selenium as a eutectic accelerator can be uniformly distributed in the composite through the Se–S bond and can accelerate the reaction kinetics. The PEO-LLZTO hybrid solid-state electrolyte (SSE) displays an attractive electrochemical performance and provides an intimate contact with electrodes. At 60 °C, Se/S–S@pPAN delivers an impressive discharge capacity of 1042 mAh g–1 at 0.1C and 445 mAh g–1 at 1C. Additionally, the LiFePO4 cathodes combined with PEO-LLZTO deliver a high reversible capacity (158.9 mAh g–1, 1C) and an ultralong lifespan (a capacity retention of 80%, 1000 cycles) at 1C. The synergetic design of the high-performance sulfur cathode and the organic/inorganic hybrid electrolyte is crucial for enabling the high-performance SSLSB

Phase Equilibria and Dissociation Enthalpies of Hydrogen Semi-Clathrate Hydrate with Tetrabutyl Ammonium Nitrate

This paper reports the experimentally determined thermodynamic stability conditions for the hydrogen semiclathrate hydrate generated from tetrabutyl ammonium nitrate (TBANO₃) aqueous solutions at two mole fractions, 0.037 and 0.030, corresponding to the stoichiometric composition for TBANO₃·26H₂O and TBANO₃·32H₂O, respectively. The experiments for this three-component TBANO₃ + water + hydrogen system were performed in the temperature range of (281.9 to 284.9) K and pressure range of (9.09 to 31.98) MPa with using a “full view” sapphire cell. An isochoric equilibrium step-heating pressure search method was employed to determine the phase boundary between hydrate–liquid–vapor (H-L-V) phases and liquid–vapor (L-V) phases. The results showed that the semiclathrate hydrate of TBANO₃·26H₂O + H₂ is more stable than that of TBANO₃·32H₂O + H₂, with both of these semiclathrate hydrates being much more stable than pure hydrogen hydrate. The obtained phase equilibria data were analyzed using the Clausius–Clapeyron equation to determine the dissociation enthalpy at the pressure range from (9 to 32) MPa. It was found that the mean dissociation enthalpies for the hydrogen–TBANO₃·26H₂O and hydrogen–TBANO₃·32H₂O clathrate hydrate systems were 322.53 kJ·mol^–1 and 340.23 kJ·mol^–1, respectively

<i>nhx5 nhx6</i> is sensitive to low K⁺ treatment.

<p>(A) Seedling growth under low K⁺ treatment. (B) Expression of <i>AtNHX5</i> and <i>AtNHX6</i> recovered <i>nhx5 nhx6</i> growth under low K⁺ treatment. (C) Root growth was measured 7 days after the seedlings were grown on the media containing various levels of KCl. Three independent experiments were performed, and about 10 seeds were counted for each experiment. Data are means SD. (D) Root growth was measured 10 days after the seedlings were grown on the media containing 0.01mM KCl. Three independent experiments were performed, and about 10 seeds were counted for each experiment. Data are means SD. (E) K⁺ content in seedlings. Three independent experiments were performed, and about 10 seeds were counted for each experiment. Data are means SD.</p

AtNHX5 and AtNHX6 facilitate K⁺ and Na⁺ transport in yeast.

<p>The overnight grown yeast cells were normalized in water to A₆₀₀ of 0.12. Aliquos (4 μL) of 10-fold serial dilutions were spotted on AP plates supplemented with KCl (A) or YPD plates with NaCl (B) and Hyg B (C). (D) Aliquos (4 μL) of 10-fold serial dilutions were spotted on AP plates supplemented with 800 mM or 0.1mM KCl at pH 4.0, 6.0 or 7.5. The strains were grown at 30°C for 3 days.</p

Three conserved acidic residues in AtNHX5 and AtNHX6 are critical for K⁺ transport in yeast.

<p>(A) Sequence alignment of AtNHX5 and AtNHX6 with yeast (<i>S</i>. <i>cerevisiae</i>) ScNhx1p identified four conserved acidic amino acids in the transmembrane domains of AtNHX5 and AtNHX6. The alignment was made by using the complete amino acid sequences, but only the predicted transmembrane domains 5, 6, and 9 are shown. (B) and (C) Yeast growth test for the point mutants of AtNHX5 and AtNHX6. The yeast strains were grown overnight in AP medium. Yeast cells were normalized in water to A₆₀₀ of 0.12. Aliquos (4 μL) of 10-fold serial dilutions were spotted on AP plates supplemented with KCl (B) or on YPD plates with Hyg B (C). The strains were grown at 30°C for 3 days.</p

Three conserved acidic residues in AtNHX5 and AtNHX6 are essential for the growth and development in <i>Arabidopsis</i>.

<p>(A) and (B) Growth phenotype of the transgenic <i>Arabidopsis</i> seedlings bearing point mutants of AtNHX5 and AtNHX6. The point mutated genes of the four conserved acidic residues of AtNHX5 and AtNHX6 were introduced into the <i>nhx5 nhx6</i> background. Photos were taken for the T3 seedlings grown in soil for 26 d. (C) and (D) The rosette size of the transgenic Arabidopsis seedlings bearing point mutants of AtNHX5 and AtNHX6. The rosette sizes were measured when the seedlings were grown in soil for 26 d.</p

AtNHX5 and AtNHX6 Control Cellular K⁺ and pH Homeostasis in <i>Arabidopsis</i>: Three Conserved Acidic Residues Are Essential for K⁺ Transport

<div><p>AtNHX5 and AtNHX6, the endosomal Na⁺,K⁺/H⁺ antiporters in <i>Arabidopsis</i>, play an important role in plant growth and development. However, their function in K⁺ and pH homeostasis remains unclear. In this report, we characterized the function of AtNHX5 and AtNHX6 in K⁺ and H⁺ homeostasis in <i>Arabidopsis</i>. Using a yeast expression system, we found that AtNHX5 and AtNHX6 recovered tolerance to high K⁺ or salt. We further found that AtNHX5 and AtNHX6 functioned at high K⁺ at acidic pH while AtCHXs at low K⁺ under alkaline conditions. In addition, we showed that the <i>nhx5 nhx6</i> double mutant contained less K⁺ and was sensitive to low K⁺ treatment. Overexpression of <i>AtNHX5</i> or <i>AtNHX6</i> gene in <i>nhx5 nhx6</i> recovered root growth to the wild-type level. Three conserved acidic residues, D164, E188, and D193 in AtNHX5 and D165, E189, and D194 in AtNHX6, were essential for K⁺ homeostasis and plant growth. <i>nhx5 nhx6</i> had a reduced vacuolar and cellular pH as measured with the fluorescent pH indicator BCECF or semimicroelectrode. We further show that AtNHX5 and AtNHX6 are localized to Golgi and TGN. Taken together, AtNHX5 and AtNHX6 play an important role in K⁺ and pH homeostasis in <i>Arabidopsis</i>. Three conserved acidic residues are essential for K⁺ transport.</p></div

<i>nhx5 nhx6</i> has a reduced cellular pH.

<p>(A) Ratio images of the epidermal cells of the mature root zone in Col-0 and <i>nhx5 nhx6</i>. (B) Vacuolar pH was reduced in epidermal cells of the mature root. The vacuolar pH was measured using the fluorescein-based ratiometric pH indicator BCECF. Error bars represent SD of 30 measurements from 15 seedlings. Asterisks indicate significant difference (P≤ 0.05; <i>t</i> test). (C) The cell sap pH of <i>nhx5 nhx</i>6 was reduced. The cell sap pH was measured from 4-week-old plants. Error bars show SD of three independent experiments. Asterisks indicate significant difference (P≤ 0.05; <i>t</i> test).</p

Subcellular localization of AtNHX5 and AtNHX6 in the <i>Arabidopsis</i> protoplasts.

<p>RFP-AtNHX5 and RFP-AtNHX6 were co-localized with the Golgi marker GFP-SYP31and TGN marker GFP-SYP41. The Golgi marker GFP-SYP31, TGN marker GFP-SYP41 or prevacuolar compartment marker Ara7-GFP was co-transformed with the RFP-AtNHX5 or RFP-AtNHX6, respectively. (A) Subcellular localization of AtNHX5. (B) Subcellular localization of AtNHX6. Scale bar = 10 μm.</p