Hydroxyapatite (HAp), Ca10(PO4)6(OH)2, is one of the most widely studied calcium phosphates in biomaterials due to its chemical similarity to the mineral phase of bone and teeth. However, its performance depends not only on its composition or crystalline phase, but also on particle size, morphology, crystallinity, surface area, porosity, and agglomeration degree. In this context, surfactants represent an effective strategy to modulate nucleation, crystal growth, and the final organization of HAp. This review analyzes cationic, anionic, nonionic, zwitterionic, and catanionic surfactant systems, whose characteristics enable interaction with the nucleation and crystal growth processes of hydroxyapatite, providing a stabilizing effect and restricting growth along specific crystallographic planes, thereby promoting controlled and oriented crystal growth. The literature shows that their effects depend on variables such as pH, supersaturation, Ca/P ratio, temperature, and reaction time. Understanding this interaction is essential for designing nanostructured HAp for biomedical applications.
The journal retracts the article titled “Efficient and Sustainable Synthesis of Dimethyl Succinate Through Oxidative Dicarbonylation of Ethylene with Oxygen as the Economical Terminal Oxidant” [...]
Stable water-in-crude-oil emulsions remain a bottleneck in the treatment of heavy Uzbek crudes, and the demulsifiers used at field level are almost entirely imported. Two local secondary streams—the xylene-rich Ustyurt pyrolysis distillate and collected waste motor oil—were converted into a multicomponent demulsifier. Xylene was sulfonated with 98 wt.% H2SO4 and neutralised to sodium xylenesulfonate (SXS), reaching 96.8% isolated yield at 110–120 °C and an acid:xylene molar ratio of 1.34:1. Fixed-time yields gave a linear Arrhenius dependence (R2 = 0.998) with an apparent activation energy of 21.7 kJ mol−1, ΔH‡ = 18.4 kJ mol−1 and ΔS‡ = −262 J mol−1 K−1, indicating a transport-influenced electrophilic substitution. FTIR confirmed the –SO3Na group, and TG/DTA showed only 5.9% mass loss below 415 °C. Of four hydrophilic–lipophilic balance estimates, only the Davies value (14.2) is compatible with the observed water solubility. The optimum formulation KS-6 (30 wt.% SXS, 50 wt.% waste oil, 18 wt.% Ca and 2 wt.% Sr stearate) gave water-separation efficiencies of 81.0, 93.7 and 98.9% at water cuts of 60, 70 and 80 vol.%, exceeding the imported reference ND-12 by factors of 1.18–1.26, and lowered the residual salt content to 125 mg dm−3.
Artificial intelligence and big data are transforming chemistry: the field is shifting from a discipline in which observations are mainly interpreted after experiments into a domain in which data, models, and experimental research form a unified, interconnected system of scientific discovery. This Perspective defines the chemical data-to-knowledge cycle and examines molecular representation, predictive modeling, synthesis planning, drug and materials discovery, large language models, and autonomous (self-driving) laboratories. The central message is that progress will depend not so much on the nominal size of a dataset or model as on chemical meaning, data provenance, uncertainty estimation, experimental validation, and the ability to convert computational results into reproducible knowledge.
Biomass provides renewable carbon for the production of fuels, chemicals, and functional materials [...]
