Szénhidrátok dehidratációja és hidrogénezése vízoldható katalizátorok jelenlétében = Dehydration and Hydrogenation of Carbohydrates in the Presence of Water Soluble Catalysts

A szénhidrátokból előállítható gamma-valerolakton (GVL) ismert fizikai és kémiai tulajdonságai, valamint a munkánk során meghatározott alacsony gőznyomása, kültéri körülmények közötti kiemelkedő stabilítása, jó égési és üzemanyag jellemzői, alacsony toxikussága és kellemes illata különösen alkalmassá teszi arra, hogy fenntartható folyadékként tárolják, szállítsák és energia és/vagy szénalapú termékek termelésére használják. Homogén vagy heterogén katalitikus reakciók megfelelő kombinációjával sikerült szacharózból kiindulva egyre kevesebb oxigént tartalmazó C5-oxigenátokat (levulinsav, GVL, 1,4-butándiol, 2-metil-THF) és végül alkánok keverékét előállítani. A szénhidrátok savak jelenlétében lejátszódó katalitikus dehitratálása során képződő levulin- és hangyasav keverékéből a ruténium alapú Shvo-katalizátor jelenlétében 100%-os szelektivítással képződik a GVL. Ez különösen azért fontos, mert kimutattuk hogy a levulinsav molekuláris hidrogénnel történő hidrogénezésével előállított GVL kismértékű redukciójában keletkező 2-metil-THF könnyen peroxidosodik, amely veszélyezteti a GVL biztonságos használatát. A GVL füst és kellemetlen illatanyagok képződése nélkül ég, jól használható faszén gyújtó folyadékaként és 95 oktánszámú benzinhez keverve az etanolhoz hasonló üzemanyag tulajdonságokat mutat. A GVL-gazdaság kialakulásának kritikus feltétele, hogy a GVL-t vagy a levulinsavat nem-ehető szénhidrátokból gazdaságosan lehessen termelni. | We have proposed that gamma-valerolactone (GVL) exhibits the most important characteristics of an ideal sustainable liquid, which could be used for the production of energy and carbon based consumer products. In addition to its known propeties, we have shown that GVL has low vapor pressure, high stability in aerobic aqueous environments, good burning and fuel properties, which make it particularly suitable for easy storage and transportation even in a large scale. The multi-step conversion of sucrose to various C5-oxygenates (levulinic acid, GVL, 1,4-butanediol, 2-methyl-THF) and alkanes was achieved by integrating various homgeneous or heterogeneous catalytic systems. The catalytic conversion of levulinic and formic acids, formed in acid catalyzed dehydration of carbohydrates, in the presence of the Ru-based Shvo-catalyst resulted in GVL with 100% selectivity. This is a very important result, since we have shown that during the catalytic hydrogenation of levulinic acid to GVL with molecular hydrogen the side product 2-methyl-THF readily forms peroxides, which could be a major safety issue. GVL burns without the formation of smoke and unpleasant smell, can be used effectively as a lighter liquid of charcoal, and has similar fuel properties to that of ethanol, when it is mixed with 95 octane gasoline

Comparison of the perioperative time courses of matrix metalloproteinase-9 (MMP-9) and its inhibitor (TIMP-1) during carotid artery stenting (CAS) and carotid endarterectomy (CEA)

Abstract Background Our aim was to compare the perioperative time courses of matrix metalloproteinase-9 (MMP-9) and its inhibitor (TIMP-1) in during carotid endarterectomy (CEA) and carotid artery stenting (CAS). Methods In our prospective study, twenty-five patients who were scheduled to undergo CAS were enrolled. We used a matched, historical CEA group as controls. Blood samples were collected at four time points: T1: preoperative; T2: 60 min after stent insertion; T3: first postoperative morning; and T4: third postoperative morning. Plasma MMP-9 and TIMP-1 levels were measured by ELISA. Results In the CEA group, the plasma levels of MMP-9 were significantly elevated at T3 compared to T1. In the CAS group, there was no significant difference in MMP-9 levels in the perioperative period. MMP-9 levels were significantly higher in the T3 samples of the CEA group compared to the CAS group. Significantly lower TIMP-1 levels were measured in both groups at T2 than at T1 in both groups. MMP-9/TIMP-1 at T3 was significantly higher than that at T1 in the CEA group compared to both T1 and the CAS group. Conclusions CAS triggers smaller changes in the MMP-9-TIMP-1 system during the perioperative period, which may correlate with a lower incidence of central nervous system complications. Additional studies as well as cognitive and functional surveys are warranted to determine the clinical relevance of our findings. Trial registration NIH U.S. National Library of Medicine, Clinicaltrials.gov,NCT03410576, 24.01.2018, Retrospectively registere

Perioperative time course of matrix metalloproteinase-9 (MMP-9), its tissue inhibitor TIMP-1 & S100B protein in carotid surgery

Background & objectives: Ischaemic stroke is a life burdening disease for which carotid endarterectomy (CEA) is considered a gold standard intervention. Pro-inflammatory markers like matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) and S-100 Beta (S100B) may have a role in the early inflammation and cognitive decline following CEA. This study was aimed to describe the perioperative time courses and correlations between of MMP-9, TIMP-1 and S100B following CEA. Methods: Fifty four patients scheduled for CEA were enrolled. Blood samples were collected at four time points, T 1 : preoperative, T 2 : 60 min after cross-clamp release, T 3 : first postoperative morning, T 4 : third postoperative morning. Twenty atherosclerotic patients were included as controls. Plasma MMP-9, TIMP-1 and S100B levels were estimated by ELISA. Results: TIMP-1 was decreased significantly in the CEA group (P<0.01). Plasma MMP-9 was elevated and remained elevated from T 1-4 in the CEA group (P<0.05) with a marked elevation in T 3 compared to T 1 (P<0.05). MMP-9/TIMP-1 was elevated in the CEA group and increased further by T 2 and T 3 (P<0.05). S100B was elevated on T 2 and decreased on T 3-4 compared to T 1 . Interpretation & conclusions: Our study provides information on the dynamic changes of MMP-9-TIMP-1 system and S100B in the perioperative period. Preoperative reduction of TIMP-1 might be predictive for shunt requirement but future studies are required for verification