TXA significantly reduced perioperative blood loss, primarily through a reduction in postoperative blood loss, in cervical laminoplasty.

Continuous reaction networks, which do not rely on purification or timely additions of reagents, serve as models for chemical evolution and have been demonstrated for compounds thought to have played important roles for the origins of life such as amino acids, hydroxy acids, and sugars. Step-by-step chemical protocols for ribonucleotide synthesis are known, but demonstrating their synthesis in the context of continuous reaction networks remains a major challenge. Herein, compounds proposed to be important for prebiotic RNA synthesis, including glycolaldehyde, cyanamide, 2-aminooxazole, and 2-aminoimidazole, are generated from a continuous reaction network, starting from an aqueous mixture of NaCl, NH4Cl, phosphate, and HCN as the only carbon source. No well-timed addition of any other reagents is required. The reaction network is driven by a combination of γ radiolysis and dry-down. γ Radiolysis results in a complex mixture of organics, including the glycolaldehyde-derived glyceronitrile and cyanamide. This mixture is then dried down, generating free glycolaldehyde that then reacts with cyanamide/NH3to furnish a combination of 2-aminooxazole and 2-aminoimidazole. This continuous reaction network models how precursors for generating RNA and other classes of compounds may arise spontaneously from a complex mixture that originates from simple reagents.

Water creates special problems for prebiotic chemistry, as it is thermodynamically favorable for amide and phosphodiester bonds to hydrolyze. The availability of alternative solvents with more favorable properties for the formation of prebiotic molecules on the early Earth may have helped bypass this so-called “water paradox”. Formamide (FA) is one such solvent, and can serve as a nucleobase precursor, but it is difficult to envision how FA could have been generated in large quantities or accumulated in terrestrial surface environments. We report here the conversion of aqueous acetonitrile (ACN) via hydrogen cyanide (HCN) as an intermediate into FA by γ-irradiation under conditions mimicking exposure to radioactive minerals. We estimate that a radioactive placer deposit could produce 0.1‒0.8 mol FA km−2 year−1. A uraninite fission zone comparable to the Oklo reactors in Gabon can produce 0.1‒1 mol m−2 year−1, orders of magnitude greater than other scenarios of FA production or delivery for which reaching sizeable concentrations of FA are problematic. Radioactive mineral deposits may be favorable settings for prebiotic compound formation through emergent geologic processes and FA-mediated organic chemistry.

Chemical evolution, from simple molecules to complex systems, is fundamental to modern origins of life research, and complex reaction networks are often supposed to have operated on the early Earth. Herein, a variety of compounds useful particularly for RNA synthesis − namely, cyanogen chloride, cyanamide, and nitrile precursors to simple sugars − are produced in short order by a chemical reaction network starting from hydrogen cyanide and driven by gamma radiolysis. The radiolytic yield of cyanamide was found to be proportional to the concentration of chloride, an often overlooked spectator anion. Aqueous irradiation of hydrogen cyanide in the presence of sodium chloride also affords cyanogen chloride, a possible intermediate in the radiolytic synthesis of cyanamide. Meanwhile, the synthesis of simple sugar precursors is proposed to proceed through a Kiliani‐Fischer homologation mechanism made possible by the reducing power of the solvated electron and hydrogen atom. Such a reaction network has the potential to serve as a model for better understanding and engineering chemical evolution of complex mixtures in the laboratory that could have happened on the early Earth.