An Artificial Lithium Protective Layer that Enables the Use of Acetonitrile‐Based Electrolytes in Lithium Metal Batteries

The resurgence of the lithium metal battery requires innovations in technology, including the use of non‐conventional liquid electrolytes. The inherent electrochemical potential of lithium metal (?3.04 V vs. SHE) inevitably limits its use in many solvents, such as acetonitrile, which could provide electrolytes with increased conductivity. The aim of this work is to produce an artificial passivation layer at the lithium metal/electrolyte interface that is electrochemically stable in acetonitrile‐based electrolytes. To produce such a stable interface, the lithium metal was immersed in fluoroethylene carbonate (FEC) to generate a passivation layer via the spontaneous decomposition of the solvent. With this passivation layer, the chemical stability of lithium metal is shown for the first time in 1 m LiPF₆ in acetonitrile.     

Thermographic validation of a novel,laminate body,analytical heat conduction model

The two-region fin model captures the heat spreading behaviour in multilayered composite bodies (i.e., laminates), heated only over a small part of their domains (finite heat source), where there is an inner layer that has a substantial capacity for heat conduction parallel to the heat exchange surface (convection cooling). This resulting heat conduction behaviour improves the overall heat transfer process when compared to heat conduction in homogeneous bodies. Long-term heat storage using supercooling salt hydrate phase change materials, stovetop cookware, and electronics cooling applications could all benefit from this kind of heat-spreading in laminates. Experiments using laminate films reclaimed from post-consumer Tetra Brik cartons were conducted with thin rectangular and circular heaters to confirm the laminate body, steady-state, heat conduction behaviour predicted by the two-region fin model. Medium to high accuracy experimental validation of the two-region fin model was achieved in Cartesian and cylindrical coordinates for forced external convection and natural convection, the latter for Cartesian only. These were conducted using constant heat flux finite heat source temperature profiles that were measured by infrared thermography. This validation is also deemed valid for constant temperature heat sources.     

Magnetic circular dichroism and absorption spectra of Cs2ZrCl6:Mo4+

Absorption and magnetic circular dichroism (M.C.D.) spectra of Mo⁴⁺ in Cs₂ZrCl₆ have been recorded under high resolution at liquid helium temperature over the range 20 000–38 000 cm^-1. All of the bands can be assigned to parity-allowed, ligand-to-metal charge-transfer transitions in both MoCl₆ ^2-(4d²) and an impurity ion which has been identified as MoOCl₅ ^2-(4d¹). The d¹ and d² systems are easily distinguished by the temperature dependence of their M.C.D. spectra, and detailed assignments are proposed for the latter. The absorption spectrum in the region 23 000–26 000 cm^-1 has recently been attributed to a d→d transition in the ion MoCl₆ ^-(4d¹) [1], but the M.C.D. spectrum proves this assignment to be incorrect, and we find no evidence for the presence of this singly-charged species. From the temperature dependence of the M.C.D. spectrum of MoCl₆ ^2-, we estimate the second-order spin-orbit splitting of the E and T ₂ components of the ³ T _1g ground state to be 27 ± 5 cm^-1 with E lowest. The electrostatic splitting of the ³ T _2u and ⁵ T _2u charge-transfer states arising from the t _1u (π + σ) →t _2g excitation is estimated to be close to 515 cm^-1.     

A study of fast and metastable dissociations of adenine-thymine binary-base oligonucleotides by using positive-ion MALDI-TOF mass spectrometry

In the present study, fast and metastable dissociations of a number of adenine-thymine binary-base oligonucleotides under the conditions of UV matrix-assisted laser desorption/ionization mass spectrometry were investigated. 2-Aminobenzoic acid/ammonium fluoride (ABA/NH4F) matrix system was used. The spectra obtained under metastable and fast dissociation conditions exhibit distinctive dissociation products. From the post-source-decay analysis, all oligonucleotides underwent predominantly metastable dissociations at the 3' C-O linkages to form [a(n)-B]+ and w(n)+ complimentary ion series. Based on the present results, the so-called "[wn+80]+" ions were postulated to be the complimentary [Z(8-n)AH]+ ions rather than the expected phosphate rearrangement products. In addition, these oligonucleotides were found to generate fast dissociation products of b(n)+, d(N)+, w(N)+ and y(N)+ ions through backbone cleavages at 5' C-O, 5' O-P, 3' C-O and 3' P-O linkages, respectively. Product ion series formed under PSD conditions were not observed. The implications of this mutually exclusive occurrence of the two sets of fragment ions under fast and metastable conditions using ABA/NH4F matrix would be discussed. A model of ion activation under UV-MALDI conditions was also proposed.     

Fleetamine (3-O-α-d-glucopyranosyl-swainsonine): the synthesis of a hypothetical inhibitor of endo-α-mannosidase

3-O-α-d-Glucopyranosyl-swainsonine was originally proposed¹⁷ as a potential inhibitor of the mammalian enzyme endo-α-mannosidase, but its synthesis has not been reported. Herein we report the total synthesis of this enigmatic compound, utilizing a halide-ion catalysed glycosylation of a swainsonine lactam with a glucosyl iodide donor as the key step. The resulting inhibitor was evaluated as an inhibitor of human endo-α-mannosidase, and as a ligand for bacterial orthologs from Bacteroides thetaiotaomicron and Bacteroides xylanisolvens, including active-centre variants, although no evidence for binding or inhibition was observed. The surprising lack of binding was rationalized by using structural alignment with an endo-α-mannosidase inhibitor complex, which identified deleterious interactions with the swainsonine piperidine ring and an essential active site residue.     

Hexagonal boron nitride nanosheets as adsorbents for solid-phase extraction of polychlorinated biphenyls from water samples

The adsorptive potential of hexagonal boron nitride nanosheets (h-BNNSs) for solid-phase extraction (SPE) of pollutants was investigated for the first time. Seven indicators of polychlorinated biphenyls (PCBs) were selected as target analytes. The adsorption of PCBs on the surface of the h-BNNSs in water was simulated by the density functional theory and molecular dynamics. The simulation results indicated that the PCBs are adsorbed on the surface by π–π, hydrophobic, and electrostatic interactions. The PCBs were extracted with an h-BNNS-packed SPE cartridge, and eluted by dichloromethane. Gas chromatography–tandem mass spectrometry working in the multiple reaction monitor mode was used for the sample quantification. The effect of extraction parameters, including the flow rate, pH value, breakthrough volume, and the ionic strength, were investigated. Under the optimal working conditions, the developed method showed low limits of detection (0.24–0.50 ng L⁻¹; signal-to-noise ratio = 3:1), low limits of quantification (0.79–1.56 ng L⁻¹; signal-to-noise ratio = 10:1), satisfactory linearity (r > 0.99) within the concentration range of 2–1000 ng L⁻¹, and good precision (relative standard deviation < 12%). The PCBs concentration in environmental water samples was determined by the developed method. This results demonstrate that h-BNNSs have high analytical potential in the enrichment of pollutants.