14 results on '"Kostas, S."'
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2. Preface
- Author
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Triantafyllidis, Kostas S., primary, Lappas, Angelos A., additional, and Stöcker, Michael, additional
- Published
- 2013
- Full Text
- View/download PDF
3. Contributors
- Author
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Aho, Atte, primary, Bergem, Håkon, additional, Bond, Jesse Q., additional, Centi, Gabriele, additional, Clark, James H., additional, Coman, Simona M., additional, da Silva, Victor Teixeira, additional, de María, Pablo Domínguez, additional, Dumesic, James A., additional, Fogassy, Gabriella, additional, Gürbüz, Elif, additional, Hannevold, Lenka, additional, Hayes, Daniel J.M., additional, Heracleous, E., additional, Kechagiopoulos, P., additional, Kiennemann, Alain, additional, Kondarides, Dimitris I., additional, Lappas, Angelos A., additional, Lødeng, Rune, additional, Lemonidou, A.A., additional, Lercher, Johannes A., additional, Luque, Rafael, additional, Matis, Konstantinos A., additional, Mihailof, Chrysa M., additional, Mirodatos, Claude, additional, Murzin, Dmitry Yu., additional, Nitsos, Christos K., additional, O'Connor, Paul, additional, Parvulescu, Vasile I., additional, Perathoner, Siglinda, additional, Ramirez-Corredores, M.M., additional, Rauch, Reinhard, additional, Román-Leshkov, Yuriy, additional, Salmi, Tapio, additional, Sauciuc, Anca, additional, Schuurman, Yves, additional, Serrano-Ruiz, Juan Carlos, additional, Sibilla, Fabrizio, additional, Sousa, Leandro A., additional, Stöcker, Michael, additional, Triantafyllidis, Kostas S., additional, Verykios, Xenophon E., additional, Voutetakis, S., additional, and Zhao, Chen, additional
- Published
- 2013
- Full Text
- View/download PDF
4. Preface
- Author
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Kostas S. Triantafyllidis, Angelos A. Lappas, and Michael Stöcker
- Published
- 2013
5. The Role of Catalytic Pretreatment in Biomass Valorization Toward Fuels and Chemicals
- Author
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Konstantinos Matis, Chrysa M. Mihailof, Angelos A. Lappas, Kostas S. Triantafyllidis, and Christos Nitsos
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Biofuel ,Enzymatic hydrolysis ,food and beverages ,Biomass ,Lignin ,Organic chemistry ,Lignocellulosic biomass ,Hemicellulose ,Cellulose ,Sugar - Abstract
The enzymatic hydrolysis of cellulose toward fermentable glucose is of paramount importance for the production of ethanol or other high-value chemicals from lignocellulosic biomass via the biochemical route. A pretreatment step is usually required that alters the structure and composition of biomass, reduces its recalcitrance, and allows the efficient enzymatic conversion of carbohydrates into sugars. Biomass pretreatment aims mainly at the selective separation of hemicellulose and/or lignin, either as oligomers or as smaller sugar and phenolic molecules, which can be further converted enzymatically or via chemical catalysis to platform chemicals or fuel precursors. In this chapter, a review of the most widely applied pretreatment methods is presented, with the aim of elucidating the role of chemical or biochemical catalysis in this first step of biomass valorization.
- Published
- 2013
6. Contributors
- Author
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Atte Aho, Håkon Bergem, Jesse Q. Bond, Gabriele Centi, James H. Clark, Simona M. Coman, Victor Teixeira da Silva, Pablo Domínguez de María, James A. Dumesic, Gabriella Fogassy, Elif Gürbüz, Lenka Hannevold, Daniel J.M. Hayes, E. Heracleous, P. Kechagiopoulos, Alain Kiennemann, Dimitris I. Kondarides, Angelos A. Lappas, Rune Lødeng, A.A. Lemonidou, Johannes A. Lercher, Rafael Luque, Konstantinos A. Matis, Chrysa M. Mihailof, Claude Mirodatos, Dmitry Yu. Murzin, Christos K. Nitsos, Paul O'Connor, Vasile I. Parvulescu, Siglinda Perathoner, M.M. Ramirez-Corredores, Reinhard Rauch, Yuriy Román-Leshkov, Tapio Salmi, Anca Sauciuc, Yves Schuurman, Juan Carlos Serrano-Ruiz, Fabrizio Sibilla, Leandro A. Sousa, Michael Stöcker, Kostas S. Triantafyllidis, Xenophon E. Verykios, S. Voutetakis, and Chen Zhao
- Published
- 2013
7. Rh-TPPTS/LDH — A new heterogeneous catalyst for the synthesis of functionalized γ-lactone
- Author
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Jean-Pierre Genêt, Florentina Neaţu, Vasile I. Pârvulescu, Kostas S. Triantafyllidis, and Véronique Michelet
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chemistry.chemical_compound ,Benzenesulfonic acid ,Cycloisomerization ,chemistry ,Hydrotalcite ,Organic chemistry ,chemistry.chemical_element ,TPPTS ,Selectivity ,Heterogeneous catalysis ,Nuclear chemistry ,Rhodium ,Catalysis - Abstract
Well defined Zn 2 Al-NO 3 /CO 3 and Zn 2 Ga-NO 3 /CO 3 LDH were prepared using typical procedures starting from Zn(NO 3 ) 2 , Al(NO 3 ) 3 and Ga(NO 3 ) 3 . Rh-TPPTS complex was prepared by simple complexation of a Rh precursor [Rh(cod)Cl]2 and TPPTS (3,3′,″-phosphanetriyl benzenesulfonic acid) in water. The heterogeneization of the Rh-TPPTS complex was performed by anionic exchange between Rh-complex and Zn 2 Al-NO 3 /CO 3 or Zn 2 Ga-NO 3 /CO 3 LDH supports. The catalysts structures and the chemical composition were confirmed by XRD analysis, XPS and DRIFT spectroscopy. Triphenylphosphane-substituted Rh heterogeneous catalysts showed good catalytic activity and selectivity in the cycloisomerization of functionalized acetylenic acids.
- Published
- 2008
8. Microporous and mesoporous aluminosilicates as catalysts for the cracking of Fischer-Tropsch waxes towards the production of 'clean' bio-fuels
- Author
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M.C. Papapetrou, Iacovos A. Vasalos, Angelos A. Lappas, Kostas S. Triantafyllidis, and Vasileios Komvokis
- Subjects
Materials science ,Catalyst support ,Organic chemistry ,Fischer–Tropsch process ,Microporous material ,Heterogeneous catalysis ,Zeolite ,Molecular sieve ,Mesoporous material ,Catalysis - Abstract
The potential utilization of various microporous (zeolites H-Y and H-ZSM-5) and mesoporous (amorphous silica-alumina and Al-MCM-41) aluminosilicates as catalysts or active matrices in the cracking of Fischer-Tropsch waxes towards the production of liquid fuels was the subject of this study. Focus was placed on the effect of porous and acidic characteristics of the materials on products yields and properties. Both zeolitic catalysts were very active leading however to different product selectivities. The moderately steamed H-Y catalyst produced more gasoline and less LPGs compared to the H-ZSM-5 catalyst. The relatively high gasoline RON values for both catalysts were attributed to the high yield of iso-alkanes and olefins in the case of the H-Y catalyst and to the high yield of aromatics in the case of H-ZSM-5. The use of mildly acidic Al-MCM-41 type mesoporous materials resulted in relatively low wax conversion activity, while the amorphous silica-alumina catalyst was almost inactive.
- Published
- 2007
9. Dehydrogenation of propane over Ga and Cr modified, 'fresh' and steamed, MFI-type zeolites
- Author
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Nicholaos P. Evmiridis, Kostas S. Triantafyllidis, Theodoros K. Katranas, and Athanasios G. Vlessidis
- Subjects
Chromium ,chemistry.chemical_compound ,chemistry ,Propane ,Inorganic chemistry ,chemistry.chemical_element ,Hydrothermal synthesis ,Dehydrogenation ,Gallium ,Selectivity ,Zeolite ,Catalysis - Abstract
In this work we synthesized MFI type zeolites with chromium and gallium. Hydrothermal synthesis was applied using, either aluminum with gallium or chromium sources in 1:1 mole ratios, or impregnation of H-ZSM-5 with the desired metal. The “as synthesized” samples were characterized by XRD, Chemical analysis, SEM-EDS, SSA, ammonia-TPD and subjected to severe steaming, in order to suppress their acidity and consequently decrease the oligomerization capability of the formed catalysts. The catalytic activity of the zeolite samples in propane dehydrogenation was investigated using a fixed-bed continuous-flow glass reactor. The catalytic test results revealed that propylene yield and selectivity over the steamed catalysts increased remarkably (e.g. propylene yield 11% with selectivity of 45%, for H-[Ga/Al]ZSM-5), as a consequence of the suppression of their acidity and therefore of the dramatic decrease of their oligomerization capability. The above results suggest that Cr- and Ga-modified steamed zeolites are promising catalysts for the dehydrogenation of propane to propylene.
- Published
- 2005
10. Formation of carbon nanotubes on iron/cobalt-modified zeolites: Effect of zeolite framework/pore structure and method of modification
- Author
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Lubos Jankovic, Dimitrios Gournis, Kostas S. Triantafyllidis, Konstantinos Dimos, and Stamatia A. Karakoulia
- Subjects
Materials science ,chemistry ,Macropore ,law ,Ammonium hexafluorosilicate ,Inorganic chemistry ,Steaming ,chemistry.chemical_element ,Carbon nanotube ,Zeolite ,Cobalt ,law.invention ,Catalysis - Abstract
The present study focuses on the effect of the metal-modification method (ion-exchange or impregnation) and of the type of dealumination procedure (steaming, AHFS) of zeolite-Y on the quantity, quality and properties of the carbon nanotubes that are formed on the supported iron or cobalt oxides. Severe dealumination of zeolite-Y by steaming, which induced secondary meso/macropores, resulted in significant decrease in the carbon nanotube formation activity of the metal-impregnated zeolite-Y catalysts, while moderate dealumination by ammonium hexafluorosilicate had a less pronounced effect. The micro-Raman spectra revealed the presence of high quality as-grown CNTs with low degree of disordered.
- Published
- 2005
11. Gas-oil cracking activity and product selectivity of the hydrothermally-stable mesoporous aluminosilicates (MSU-S) assembled from zeolite seeds
- Author
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Kostas S. Triantafyllidis, Yu Liu, Thomas J. Pinnavaia, Angelos A. Lappas, and Iacovos A. Vasalos
- Subjects
Cracking ,Chemical engineering ,Chemistry ,Inorganic chemistry ,Coke ,Fuel oil ,Gasoline ,Zeolite ,Mesoporous material ,Selectivity ,Catalysis - Abstract
The hydrothermally-stable and acidic MSU-S aluminosilicates assembled from zeolite seeds has been shown to be significantly more active in the cracking of gas-oil, compared to an amorphous commercial silica-alumina catalyst, after moderate steaming pretreatment. When compared to a similarly steamed H-Y based catalyst at constant conversion, the MSU-S catalytic material produced less gasoline and more LCO, while it was more selective for the production of propylene and butylenes, as well as of gasoline range alkenes. The differences in catalytic activity and product selectivity were related to differences in the pore structure/size and in the nature/strength of the acid sites of the tested materials. When the MSU-S materials were tested as FCC catalyst additives, at a concentration level of 8 wt.% on total catalyst weight, they induced higher conversion of gas-oil, mainly due to the increase of LPGs, coke and gasoline range aromatics.
- Published
- 2004
12. The role of endothelial shear stress, shear stress gradient, and plaque topography in plaque erosion.
- Author
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Hakim D, Pinilla-Echeverri N, Coskun AU, Pu Z, Kajander OA, Rupert D, Maynard C, Cefalo N, Siasos G, Papafaklis MI, Kostas S, Michalis LK, Jolly S, Mehta SR, Sheth T, Croce K, and Stone PH
- Subjects
- Humans, Female, Endothelium, Vascular, Coronary Angiography, Heart, Coronary Vessels diagnostic imaging, Coronary Artery Disease diagnostic imaging, Plaque, Atherosclerotic
- Abstract
Background and Aims: Plaque erosion is a common underlying cause of acute coronary syndromes. The role of endothelial shear stress (ESS) and endothelial shear stress gradient (ESSG) in plaque erosion remains unknown. We aimed to determine the role of ESS metrics and maximum plaque slope steepness in plaques with erosion versus stable plaques., Methods: This analysis included 46 patients/plaques from TOTAL and COMPLETE trials and Brigham and Women's Hospital's database who underwent angiography and OCT. Plaques were divided into those with erosion (n = 24) and matched stable coronary plaques (n = 22). Angiographic views were used to generate a 3-D arterial reconstruction, with centerlines merged from angiography and OCT pullback. Local ESS metrics were assessed by computational fluid dynamics. Among plaque erosions, the up- and down-slope (Δ lumen area/frame) was calculated for each culprit plaque., Results: Compared with stable plaque controls, plaques with an erosion were associated with higher max ESS (8.3 ± 4.8 vs. 5.0 ± 1.9 Pa, p = 0.02) and max ESSG any direction (9.2 ± 7.5 vs. 4.3 ± 3.11 Pa/mm, p = 0.005). Proximal erosion was associated with a steeper plaque upslope while distal erosion with a steeper plaque downslope. Max ESS and Max ESSG any direction were independent factors in the development of plaque erosion (OR 1.32, 95%CI 1.06-1.65, p = 0.014; OR 1.22, 95% CI 1.03-1.45, p = 0.009, respectively)., Conclusions: In plaques with similar luminal stenosis, plaque erosion was strongly associated with higher ESS, ESS gradients, and plaque slope as compared with stable plaques. These data support that ESS and slope metrics play a key role in the development of plaque erosion and may help prognosticate individual plaques at risk for future erosion., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)
- Published
- 2023
- Full Text
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13. Multimarker strategy for the prediction of 31 days cardiac death in patients with acutely decompensated chronic heart failure.
- Author
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Zairis MN, Tsiaousis GZ, Georgilas AT, Makrygiannis SS, Adamopoulou EN, Handanis SM, Batika PC, Prekates AA, Velissaris D, Kouris NT, Mytas DZ, Babalis DK, Karidis KS, and Foussas SG
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- Acute Disease, Aged, Aged, 80 and over, C-Reactive Protein metabolism, Cardiac Output, Chronic Disease, Female, Follow-Up Studies, Humans, Male, Multivariate Analysis, Natriuretic Peptide, Brain blood, Predictive Value of Tests, Prognosis, Proportional Hazards Models, ROC Curve, Risk Factors, Severity of Illness Index, Troponin I blood, Biomarkers blood, Death, Sudden, Cardiac epidemiology, Heart Failure blood, Heart Failure diagnosis, Heart Failure mortality
- Abstract
Background: To investigate the combined prognostic value of admission serum levels of B-type natriuretic peptide (BNP), cardiac troponin I (cTnI) and high sensitivity C-reactive protein (hs-CRP), in patients hospitalized because of acutely decompensated severe (New York Heart Association class III/IV) low-output chronic heart failure (CHF)., Methods: A total of 577 consecutive patients recruited in the 5 participating centers, were studied. Cardiac mortality by 31 days was the prespecified primary study end point., Results: A total of 102 (17.7%) patients died by 31 days. When the study patients were divided according to the number of elevated study biomarkers, there was a significant gradual increased risk of 31-day cardiac death with increasing in the number of elevated biomarkers (p<0.001). The value of the discriminant C statistic for the Cox regression analysis, increased significantly when each of the study biomarkers was incorporated with the other risk predictors into a Cox regression model, with the highest C statistic value for the Cox regression model that included all the study biomarkers (p<0.001). By multivariate Cox regression analysis, elevated serum levels of BNP (p=0.002), cTnI (p<0.001) and hs-CRP (p=0.02) were independent predictors of the study end point., Conclusions: In conclusion, in patients hospitalized for acute decompensation of severe (NYHA III/IV) low-output CHF, BNP, cTnI and hs-CRP upon admission offers enhanced early risk stratification. With increasing number of elevated biomarkers, the risk of 31-day cardiac death increases gradually that implies treatment intensification, and closer follow-up., (Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2010
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14. The MADS-Box factor CeMEF2 is not essential for Caenorhabditis elegans myogenesis and development.
- Author
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Dichoso D, Brodigan T, Chwoe KY, Lee JS, Llacer R, Park M, Corsi AK, Kostas SA, Fire A, Ahnn J, and Krause M
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- Amino Acid Sequence, Animals, Caenorhabditis elegans genetics, Caenorhabditis elegans Proteins metabolism, Cloning, Molecular, Conserved Sequence, DNA-Binding Proteins metabolism, Evolution, Molecular, Gene Deletion, MEF2 Transcription Factors, Molecular Sequence Data, Myogenic Regulatory Factors, Protein Binding, Tissue Distribution, Transcription Factors metabolism, Caenorhabditis elegans embryology, Caenorhabditis elegans Proteins genetics, DNA-Binding Proteins genetics, Genes, Helminth, Muscles embryology, Transcription Factors genetics
- Abstract
MEF2 is an evolutionarily conserved MADS (MCM1, Agamous, Deficiens, and serum response factor) box-type transcription factor that plays a critical role in vertebrate and Drosophila melanogaster myogenesis. We have addressed the developmental role of the single MEF2-like factor, CeMEF2, in Caenorhabditis elegans. Using expression assays and two mef-2 deletion alleles, we show that CeMEF2 is not required for proper myogenesis or development. Moreover, a putative null mef-2 allele fails to enhance or suppress the phenotypes of mutants in CeMyoD or CeTwist. Our results suggest that despite its evolutionary conservation of sequence and DNA binding properties, CeMEF2 has adopted a divergent role in development in the nematode compared with Drosophila and vertebrates.
- Published
- 2000
- Full Text
- View/download PDF
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