Liquids

This work reports on novel acid–base conjugate pairs of monocationic allyldiamidinium and dicationic diamidinium salts, some of which are ionic liquids (ILs) at ambient temperatures. A series of allyldiamidinium salts of the general formula [C₃H(NRMe)₄]X (R = Me, Et, Pr, allyl, CH₂CH₂OMe; X = Cl, bistriflimide, dicyanamide) were prepared from C₃Cl₄ or C₃Cl₅H and the appropriate secondary amine, RNMeH. Alkylated ethylenediamines similarly yield bicyclic allyldiamidinium salts, whereas longer diamines (H₂N(CH₂)_nNH₂ (n = 3, 4, 5)) were isolated as their conjugate acids, the diamidinium dicationic salts [C₃H₂(HN(CH₂)_nNH)₂]X₂. The salts were characterized by NMR, ES-MS, DSC, TGA, and miscibility or solubility studies. Additionally, the ILs were characterized by their viscosities. The conductivities of the diamidinium ILs were also measured, and this allowed for an investigation of their Walden parameters. In contrast to expectations, since the ion pairing and clustering were expected to be significant, this showed them to be “superionic”. Previous reports of Walden plots of dicationic ILs were found to be erroneous, and a reanalysis of the literature data found that all reported dicationic and even tetracationic ILs can be classified as superionic. The salts [C₃H(NMe₂)₄]Cl, [C₃H(EtN(CH₂)₂NEt)₂]OTf, and [C₃H₂(HN(CH₂)_nNH)₂]Cl₂ (n = 3, 4, 5) were also characterized by single-crystal X-ray diffraction.

(1) Background: Fixed-dose combination (FDC) improves patient convenience and therapeutic adherence by combining suitable drugs in a single dose form. This study examined the in vitro dissolution of an ibuprofen-loratadine FDC oral suspension to commercial reference formulations. (2) Methods: The FDC suspension (ibuprofen 200 mg/5 mL, loratadine 5 mg/5 mL) was tested against Fenbro 8 Plus and Lorid on USP Apparatus II at 50 rpm and 37 ± 0.5 °C. Dissolution testing was carried out in 900 mL of phosphate buffer (pH 7.2) for ibuprofen and 0.1 N HCl (pH 3.3) for loratadine. Quantification was performed using validated high-performance liquid chromatography linked with ultraviolet detector (HPLC-UV) procedures complying with the ICH Q2 (R²) guidelines. (3) Results: The linearity of the HPLC methods for ibuprofen and loratadine was (R² > 0.99), accuracy (99.6–100.18%), and precision (%RSD < 2). For both loratadine and ibuprofen, the FDC suspension’s Q₁₅, Q₃₀, T₅₀, T₉₀, and DE% values nearly matched those of the commercial products. Over 95% of both drugs were released within 60 min. The dissolution equivalence between the FDC and the reference formulations was demonstrated by the calculated similarity (f₂) and difference (f₁) factors, which were f₁ = 3 and f₂ = 70 for ibuprofen, and f₁ = 4 and f₂ = 64 for loratadine. (4) Conclusions: The FDC suspension of ibuprofen and loratadine showed dissolving behavior comparable to commercial formulations, confirming its applicability for the practical and efficient treatment of allergy symptoms and inflammatory pain.

Specifically engineered heavy liquid metals are proposed as candidate coolants and tritium breeders for advanced nuclear applications. Understanding the wetting behaviours of these liquids on relevant substrate configurations is crucial to tackle the challenges associated with corrosion protection and flow diagnostics development. However, detailed investigations are scarce in the literature. In this experimental study, an apparatus is designed to measure contact angles of different liquid metals over a mirror-polished horizontal SS-304 substrate. This paper presents design aspects of the developed test facility, as well as initial results obtained using direct imaging and the Low-Bond Axisymmetric Drop Shape Analysis algorithm-based image processing technique. Methodological validation is achieved through surrogate liquids/liquid metals (H₂O, Hg, Ga, GaInSn), prior to taking measurements from molten lead (Pb) droplets at 425 °C. Estimated contact angles obtained using the two techniques lie within ±10% deviation. Towards the end, the paper lays out plans for future upgrades for studies of wetting behaviours of molten Pb/Pb alloys on substrates with relevant surface properties, including bare P-91 and reduced-activation ferritic–martensitic steels, along with Al₂O₃/Er₂O₃-coated versions of these materials, to generate a database for Gen-IV fission reactors and fusion power plants.