RESUMO
Pretreatment and densification of agricultural residues at regional depots can simplify feedstock supply logistics for the production of biofuels in commercial biorefineries. We have previously reported the performance of a laboratory-scale (5 L) packed-bed ammonia fiber expansion (AFEX) reactor system, which showed significant promise for biomass pretreatment at distributed depots. In this paper, we describe the performance of a 90-fold larger pilot-scale packed-bed AFEX-reactor system, used to produce over 1,500 batches (~36 tons) of pretreated crop residues over a 5-year period. Virtually all unreacted ammonia was successfully removed from the biomass, and 76% of the ammonia was recycled and reused. Pretreatment performance at pilot scale was comparable to laboratory-scale, averaging 74% glucose and 75% xylose yield in a standard test compared with 71% and 73%, respectively. Other operating and maintenance aspects are also discussed.
Assuntos
Amônia/química , Biomassa , Reatores Biológicos , Produtos Agrícolas , Desenho de Equipamento , Projetos Piloto , Poaceae/químicaRESUMO
Acetamide has been classified as a possible human carcinogen, but uncertainties exist about its levels in foods. This report presents evidence that thermal decomposition of N-acetylated sugars and amino acids in heated gas chromatograph injectors contributes to artifactual acetamide in milk and beef. An alternative gas chromatography/mass spectrometry protocol based on derivatization of acetamide with 9-xanthydrol was optimized and shown to be free of artifactual acetamide formation. The protocol was validated using a surrogate analyte approach based on d3-acetamide and applied to analyze 23 pasteurized whole milk, 44 raw sirloin beef, and raw milk samples from 14 different cows, and yielded levels about 10-fold lower than those obtained by direct injection without derivatization. The xanthydrol derivatization procedure detected acetamide in every food sample tested at 390 ± 60 ppb in milk, 400 ± 80 ppb in beef, and 39â¯000 ± 9000 ppb in roasted coffee beans.
Assuntos
Acetamidas/análise , Café/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Carne/análise , Leite/química , Animais , Bovinos , Xantenos/químicaAssuntos
Relações Enfermeiro-Paciente , Cuidados de Enfermagem/normas , Idoso , Feminino , Humanos , MasculinoRESUMO
Robert Julian-Allen's hospital stay was notable for the carelessness and cruelty he saw and experienced. He thinks there are important issues for managers to address.