Construction of KB@ZIF-8/PP Composite Separator for Lithium–Sulfur Batteries with Enhanced Electrochemical Performance

Lithium–sulfur batteries (LSBs) have attracted wide attention, but the shuttle effect of polysulfide hinders their further practical application. Herein, we develop a new strategy to construct a Ketjen black@zeolite imidazole framework-8/polypropylene composite separator. Such a separator consists of Ketjen black (KB), zeolite imidazole framework-8 (ZIF-8) and polypropylene (PP) with a low coating load of 0.06 mg cm−2 and is denoted as KB@ZIF-8/PP. KB@ZIF-8/PP can absorb polysulfides because of the Lewis acid-base interaction between ZIF-8 and polysulfides. This interaction can reduce the dissolution of polysulfides and suppress the shuttle effect, thereby enhancing the electrochemical performance of the battery. When tested at a current density of 0.1 C, an LSB with a KB@ZIF-8/PP separator exhibits low polarization and achieves a high initial capacity of 1235.6 mAh/g and a high capacity retention rate of 59.27% after 100 cycles.

Effect of new crystalline phase on the ionic conduction properties of sodium perchlorate salt doped carboxymethyl cellulose biopolymer electrolyte films

Dopant induced modifications in the microstructure of sodium carboxymethyl cellulose (NaCMC) were characterized by FTIR, XRD, DSC and EIS techniques. FTIR analysis exhibited a considerable microstructural modification in NaCMC upon NaClO4⋅H2O doping invoked through complex formation via Lewis acid-base interaction and hydrogen bond formation between ions and dipoles. This resulted in the modification in the orderliness/disorderliness of polymer chains as observed from XRD deconvolution. At higher salt concentrations, the complexity of the network causes the formation of new amorphous and crystalline phases as reflected in the XRD studies. DSC analysis showed an increase in Tg as the salt concentration increased, indicating a reduction in polymer chains flexibility. The contribution of free ions has masked over the enhancement in amorphous content to conductivity at a lower concentration of salt in the matrix, later on, the formation of a new crystalline phase due to transient crosslinks by Na+…ClO4−…Na+ has affected the ion transport process.

Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing

Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto’s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2–7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their supramolecular binding to a series of zinc porphyrins was studied with UV-Vis and circular dichroism (CD) spectroscopy, computational analysis and single crystal X-ray diffraction. The association constant values generally increased with the increasing electron-withdrawing properties of the porphyrins and electron-donating ability of the thioureas, a result of the predominant Zn⋯N cation–dipole (Lewis acid–base) interaction. The binding event induced a CD signal in the Soret band region of the porphyrin hosts—a crucial property for chirality sensing of Takemoto-type thioureas.

Artemisinin DNA Base Interaction Studies in Presence of Fe(II): LC/TOF MS Separation of Reaction Products

Artemisinin (ART) is a sesquiterpene lactone and a popular malaria drug with potential anticancer properties. In this work, LC/TOF/MS, was used to investigate the reaction of ART with DNA bases. ART-deoxyadenosine and ART-deoxycytidine interactions, were studied in the presence of iron II ions. ART-deoxyadenosine and ART-deoxycytidine reaction mixtures gave chromatographic signatures that remained fairly unchanged at room temperature but grew after incubation at 37 °C. The change in temperature from room temperature to 37 °C was the main driver of adduct formation in these reactions. ART was found to react with Fe(II) ions as observed from several new chromatographic peaks. ART-deoxyadenosine as well as ART-deoxycytidine in the presence of Fe(II) ions resulted in formation of new chromatographic signatures of adducts consisting of DNA bases and ART. It was clear that addition of iron (II) to DNA base-ART mixtures gave rise to new reaction products mediated by a different reaction mechanism. Studies of ART reactions with DNA in vitro is key in elucidating elusive mechanism of this drug.

Development of accounting for social media marketing services (SMM)

Accountants of agencies and studios that provide advertising services of this type ask themselves the question: «How to keep records of works on popularizing brands in social networks?». The current regulatory framework does not give clear recommendations on how to account for transactions in the provision of marketing services in social networks, and not so many foreign and Ukrainian specialists have studied the accounting nuances of SMM. Therefore, taking into account the specifics of the object under study, a number of proposals were made to the working chart of accounts in terms of synthetic accounting on accounts 23 «Main production» and 05 «Guarantees and collateral provided» for web studios and marketing agencies, which will allow differentiating the costs incurred in the process of activities and, along with this, improving the accounting process in terms of the formation of the cost of SMM services. The order of accounting reflection of the budget provided by the customer on the off-balance account is proposed, which allows you to control the movement of funds received and track the directions of their use. Inadequate documentation of SMM transactions raises many questions from the fiscal regulatory authorities. The article develops documentary support for the purposes of accounting for marketing services in social networks (SMM). The effect of the implementation of the developed form «Act of acceptance and transfer of services rendered for SMM» is the possibility of highlighting the volume of marketing work performed and confirmation of the economic effect obtained (increase in sales, customer base, interaction with the brand, etc.), which will prevent the occurrence of conflict situations between the customer of services and the SFSU authorities regarding the inclusion of VAT amounts in the tax credit and the possibility of avoiding the accrual of «compensating» tax liabilities.

BUFFER SOLUTIONS BASED ON TAURINE

The acid-base interaction in the aminoethanesulfonic acid (taurine, Tau) – potassium aminoethanesulfonate – water system was studied by pH-, redox- and conductometric methods in the temperature range 293–313 K. The ion-molecular composition of NH2CH2CH2SO3H –NH2CH2CH2SO3K – H2O system was calculated. It is shown aminoethanesulfonic acid in aqueous solutions to exist at the ratio CKOH/QTau < 0.5 mainly in the zwitterion form similar to systems with glycine, aminomethanesulfonic acid and its N‑alkylated derivatives. The content of the aminoethanesulfonate anion is directly proportional to the CKOH/QGly ratio. The studied system ionic strength and acid-base dissociation constant for the second stage of the aminoethanesulfonic acid concentration and temperature dependences were determined. The ionic strength values at the isoelectric point (mi.p.)are directly proportional to С0Tau and practically do not depend on the temperature within the error for the same series С0Tau and С0KOH .The pH limits of the buffer action are determined and the buffer capacity of these systems is estimated. It has been established that effective buffer zones of Tau aqueous solutions can to maintain acidity in the higher then physiological pH range at temperature range 293–313 K. The buffer capacity of NH2CH2CH2SO3H – NH2CH2CH2SO3K – H2O system exceeds the analogous values of YNHCH2SO3H – YNHCH2SO3K – H2O (Y = H, CH3, CH2CH2OH, C(CH3)3 and C2H5C6H5) systems. The obtained data on the buffer capacity of the aminoethanesulfonic acid – potassium aminoethanesulfonate – water system can be used in chemical analysis, microbiological and biochemical studies, and the acidity data of the solutions studied can simulate the chemisorption of acid gases (carbon and sulfur dioxides).

Increased Ion Conductivity in Composite Solid Electrolytes With Porous Co3O4 Cuboids

Compared with the fagile ceramic solid electrolyte, Li-ion conducting polymer electrolytes are flexible and have better contact with electrodes. However, the ionic conductivity of the polymer electrolytes is usually limited because of the slow segment motion of the polymer. In this work, we introduce porous Co3O4 cuboids to Poly (Ethylene Oxide)-based electrolyte (PEO) to investigate the influence of these cuboids on the ionic conductivity of the composite electrolyte and the performance of the all-solid-state batteries. The experiment results showed the porous cuboid Co3O4 fillers not only break the order motion of segments of the polymer to increase the amorphous phase amount, but also build Li+ continuous migration pathway along the Co3O4 surface by the Lewis acid-base interaction. The Li+ conductivity of the composite polymer electrolyte reaches 1.6 × 10−4 S cm−1 at 30°C. The good compatibility of the composite polymer electrolyte to Li metal anode and LiFePO4 cathode ensures good rate performance and long cycle life when applying in an all-solid-state LiFePO4 battery. This strategy points out the direction for developing the high-conducting composite polymer electrolytes for all-solid-state batteries.