(S)-2-Aminononanoic acid

The development of a Lewis acid-catalyzed, intramolecular ring-opening benzannulation of 5-(indolyl)2,3-dihydrofuran acetals is described. The resulting 1-hydroxycarbazole-2-carboxylates are formed in up to 90% yield in 1 h. The dihydrofuran acetals are readily accessed from the reactions of enol ethers and α-diazo-β-indolyl-β-ketoesters. To highlight the method's synthetic utility, a formal total synthesis of murrayafoline A, a bioactive carbazole-containing natural product, was undertaken.

Sulfide precipitation is an extensively used method to precipitate metal and arsenic from acidic wastewater, whereas the tiny and negatively-charged metal sulfides with poor settling performance are generated. The factors and mechanisms that influence particle size and settling performance remain unclear. Herein, the effects of sulfuration factors, e.g., reagent dosage, acidity and H2S release rate on the particle size and settling performance of metal sulfides were investigated, and involved mechanisms were systematically revealed. The results showed that the reagent dosage and acidity had a limited effect on particle size and settling performance while the H2S release rate played a critical role. Under homogeneous conditions, the decrease in H2S release rate, which can reduce the initial supersaturation and supply the sustainable supersaturation, increased the particle size of metal sulfides generated using Na2S solution. Under heterogeneous conditions, the decrease in H2S release rate further increased the particle size of metal sulfides generated using low-solubility CaS/FeS and further improved settling performance, in which heterogeneous nucleation played a crucial role besides supersaturation. The developed dissolution-diffusion-growth model qualitatively explained the negative relationship between H2S release rate and particle growth. This work provides implications for improving the settling performance of metal sulfides in acidic wastewater.

Aims/hypothesis: Studies suggest a potential link between low-grade metabolic acidosis and type 2 diabetes. A western dietary pattern increases daily acid load but the association between diet-dependent acid load and type 2 diabetes is still unclear. This study aimed to assess whether diet-dependent acid load is associated with the risk of type 2 diabetes. Methods: We examined the association between energy-adjusted net endogenous acid production (NEAP), potential renal acid load (PRAL) and animal protein-to-potassium ratio (A:P) on incident type 2 diabetes in 67,433 women from the Nurses' Health Study, 84,310 women from the Nurses' Health Study II and 35,743 men from the Health Professionals' Follow-up Study who were free from type 2 diabetes, cardiovascular disease and cancer at baseline. Study-specific HRs were estimated using Cox proportional hazards models with time-varying covariates and were pooled using a random effects meta-analysis. Results: We documented 15,305 cases of type 2 diabetes during 4,025,131 person-years of follow-up. After adjustment for diabetes risk factors, dietary NEAP, PRAL and A:P were positively associated with type 2 diabetes (pooled HR [95% CI] for highest (Q5) vs lowest quintile (Q1): 1.29 [1.22, 1.37], p trend <0.0001; 1.29 [1.22, 1.36], p trend <0.0001 and 1.32 [1.24, 1.40], p trend <0.0001 for NEAP, PRAL and A:P, respectively). These results were not fully explained by other dietary factors including glycaemic load and dietary quality (HR [95% CI] for Q5 vs Q1: 1.21 [1.09, 1.33], p trend <0.0001; 1.19 [1.08, 1.30] and 1.26 [1.17, 1.36], p trend <0.0001 for NEAP, PRAL and A:P, respectively). Conclusions/interpretation: This study suggests that higher diet-dependent acid load is associated with an increased risk of type 2 diabetes. This association is not fully explained by diabetes risk factors and overall diet quality.