Search results for "Levulinic acid"
showing 5 items of 35 documents
Simultaneous production of furfural and levulinic acid from pine sawdust via acid-catalysed mechanical depolymerization and microwave irradiation
2019
Abstract In this work pine sawdust was converted into levulinic acid (LA) and furfural. Sawdust was first pre-treated with sulfuric acid-catalysed mechanical depolymerization. The conversion reactions were then performed with microwave heating at 180 °C. To enhance the furfural yield and the efficient separation of furfural and LA, a biphasic water-toluene reaction system was used. The effect of an additional catalyst, AlCl3, on the yield of LA and furfural was also studied. According to the results the pre-treatment method enhanced the yields of LA. In addition, due to the microwave heating the reaction times were short. Additional AlCl3 catalyst enhanced the LA yield, however excellent fu…
Feasibility and Diagnostic Impact of Fluorescence-Based Diagnostic Laparoscopy in Hepatocellular Carcinoma: A Case Report
2002
Fluorescence-based diagnostic techniques are an evolving field in the staging of hepatologic and gastroenterologic malignancies. The method aims at improved accuracy in the detection of locoregional and distant metastases. In hepatocellular carcinoma, detection of metastases is of utmost importance, because advanced tumors preclude curative surgical therapy. We present here our first experience of fluorescence-based diagnostic laparoscopy in a patient with hepatocellular carcinoma. We performed diagnostic laparoscopy in a 76-year-old woman who presented with a tumor of the liver and increased serum levels of alpha-fetoprotein. For photosensitization, 5-aminolevulinic acid (20 mg/kg bodyweig…
Fluorescein for resection of high-grade gliomas: A safety study control in a single center and review of the literature
2017
Background: The importance of a complete resection of high-grade gliomas (HGGs) has been highlighted in scientific literature, in order to limit tumor recurrence and above all to improve disease-free survival rates. Several fluorescent biomarkers have been tested to improve intraoperative identification of residual tumor; 5-aminolevulinic acid (5-ALA) and fluorescein sodium (FS) are now starting to play a central role in glioma surgery. We performed a retrospective analysis on 47 patients operated for HGGs. Here we report our preliminary data. Methods: Data of 47 consecutive patients with HGG have been collected in our study (25 males, 22 females; mean age: 60.3 years, range: 27-86 years). …
Long-Segment Early Squamous Cell Carcinoma of the Proximal Esophagus: Curative Treatment and Long-Term Follow-Up after 5-Aminolevulinic Acid (5-ALA)-…
2006
Photodynamic therapy (PDT) is an established treatment for the ablation of dysplastic Barrett's epithelium and early esophageal carcinoma, but no data have been published on curative 5-aminolevulinic acid (5-ALA)-PDT for long-segment early esophageal cancer with infiltration of the upper sphincter. We describe successful curative treatment of an unusual early long-segment squamous cell carcinoma (uT1a,N0) of the proximal esophagus (18 - 28 cm aborally), with three sessions of 5-ALA-PDT. Endoscopic and endosonographic follow-up macroscopically showed a complete remission of the tumor, proven by biopsy showing total histological ablation. After a follow-up period of 23 months, there has been …
Microwave-assisted conversion of novel biomass materials into levulinic acid
2018
Levulinic acid is considered one of the most important platform chemicals. It is currently produced mainly from lignocellulosic biomasses. However, there are also other abundant biomass materials, which could be used as raw materials for levulinic acid production. In this work, levulinic acid was produced from two novel biomasses in the presence of Brønsted (H2SO4) and Lewis acid (CrCl3·6H2O or AlCl3·6H2O) catalysts. The studied materials were carbohydrate-rich potato peel waste and sporocarps of the fungus Cortinarius armillatus. Reaction conditions, i.e., time, temperature, H2SO4, and Lewis acid concentrations, were studied by utilizing full 24-factorial experimental designs. Microwave ir…