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Boháč M, Zezulová A, Krejčí Kotlánová M, Kubátová D, Staněk T, Krejza Z, Všianský D, Novotný R, Palovčík J, Dvořák K. Early hydration of C 4AF with silica fume and its role on katoite composition. J Microsc 2024; 294:168-176. [PMID: 38418930 DOI: 10.1111/jmi.13280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 03/02/2024]
Abstract
C4AF is considered the least reactive main clinker phase, but its reactivity may be affected by adding supplementary cementitious materials (SCMs). Pure C4AF was synthesised in a laboratory furnace, and the role of silica fume without gypsum on its early hydration properties was monitored. Burning was carried out in four stages to achieve 99% purity of C4AF. Heat flow development was monitored by isothermal calorimetry over 7 days of hydration at 20°C and 40°C. The role of silica fume on hydrogarnet phase katoite (Ca3Al2(SiO4)3 - x(OH)4 x x = 1.5-3) formation during early hydration was studied. Rapid dissolution of C4AF, formation of metastable C-(A,F)-H and its conversion to C3(A, F)H6 was evidenced by isothermal calorimetry as a large exotherm. Changes in microstructure during early hydration were documented by SE micrographs, EDS point analyses, X-ray mapping and line scans by SEM-EDS. The phase composition was characterised by DTA-TGA and QXRD after 7 days of hydration. The katoite diffraction pattern is similar for the reference sample and sample with silica fume, but substitution in its structure can be revealed by X-ray microanalyses. The composition of katoite is variable due to the various extent of substitution of 4OH- by SiO4 4- due to silica fume.
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Affiliation(s)
- Martin Boháč
- Research Institute for Building Materials, Brno, Czech Republic
| | - Anežka Zezulová
- Research Institute for Building Materials, Brno, Czech Republic
| | | | - Dana Kubátová
- Research Institute for Building Materials, Brno, Czech Republic
| | - Theodor Staněk
- Research Institute for Building Materials, Brno, Czech Republic
| | - Zdeněk Krejza
- Research Institute for Building Materials, Brno, Czech Republic
| | - Dalibor Všianský
- Faculty of Science, Department of Geological Sciences, Masaryk University, Brno, Czech Republic
| | - Radek Novotný
- Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Jakub Palovčík
- Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Karel Dvořák
- Faculty of Civil Engineering, Institute of Technology of Building Materials and Components, Brno University of Technology, Brno, Czech Republic
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Ravaszová S, Dvořák K, Boháč M, Všianský D, Jančíková A. Formation, Stability, and Crystallinity of Various Tricalcium Aluminate Polymorphs. Materials (Basel) 2024; 17:735. [PMID: 38591982 PMCID: PMC10856400 DOI: 10.3390/ma17030735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/12/2024] [Accepted: 01/31/2024] [Indexed: 04/10/2024]
Abstract
Tricalcium aluminate is an important phase of Portland clinker. In this paper, three polymorphs of C3A were prepared by means of the solid-state synthesis method using intensive milling of the raw material mixture which was doped with various amounts of Na2O and sintered at a temperature of 1300 °C for 2 h. The final products were evaluated through X-ray diffraction using Rietveld analysis. The effect of the Na dopant content on the change in the crystalline structure of tricalcium aluminate was studied. It was proven that the given preparation procedure, which differed from other studies, was close to the real conditions of the formation of Portland clinker, and it was possible to prepare a mixture of different polymorphs of calcium aluminate. Fundamental changes in the crystal structure occurred in the range of 3-4% Na, when the cubic structure changes to orthorhombic. At a dosage of Na dopant above 4%, the orthorhombic structure changes to a monoclinic structure. There are no clearly defined boundaries for the existence of individual C3A phases; these phases arise at the same time and overlap each other in the areas of their formation at different Na doses.
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Affiliation(s)
- Simona Ravaszová
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (S.R.); (A.J.)
| | - Karel Dvořák
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (S.R.); (A.J.)
| | - Martin Boháč
- Research Institute for Building Materials, Hněvkovského 30/65, 617 00 Brno, Czech Republic;
| | - Dalibor Všianský
- Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37 Brno, Czech Republic;
| | - Andrea Jančíková
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (S.R.); (A.J.)
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Šmíd V, Dvořák K, Stehnová K, Strnad H, Rubert J, Stříteský J, Staňková B, Stránská M, Hajšlová J, Brůha R, Vítek L. The Ameliorating Effects of n-3 Polyunsaturated Fatty Acids on Liver Steatosis Induced by a High-Fat Methionine Choline-Deficient Diet in Mice. Int J Mol Sci 2023; 24:17226. [PMID: 38139055 PMCID: PMC10743075 DOI: 10.3390/ijms242417226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/02/2023] [Accepted: 12/03/2023] [Indexed: 12/24/2023] Open
Abstract
The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is associated with abnormalities of liver lipid metabolism. On the contrary, a diet enriched with n-3 polyunsaturated fatty acids (n-3-PUFAs) has been reported to ameliorate the progression of NAFLD. The aim of our study was to investigate the impact of dietary n-3-PUFA enrichment on the development of NAFLD and liver lipidome. Mice were fed for 6 weeks either a high-fat methionine choline-deficient diet (MCD) or standard chow with or without n-3-PUFAs. Liver histology, serum biochemistry, detailed plasma and liver lipidomic analyses, and genome-wide transcriptome analysis were performed. Mice fed an MCD developed histopathological changes characteristic of NAFLD, and these changes were ameliorated with n-3-PUFAs. Simultaneously, n-3-PUFAs decreased serum triacylglycerol and cholesterol concentrations as well as ALT and AST activities. N-3-PUFAs decreased serum concentrations of saturated and monounsaturated free fatty acids (FAs), while increasing serum concentrations of long-chain PUFAs. Furthermore, in the liver, the MCD significantly increased the hepatic triacylglycerol content, while the administration of n-3-PUFAs eliminated this effect. Administration of n-3-PUFAs led to significant beneficial differences in gene expression within biosynthetic pathways of cholesterol, FAs, and pro-inflammatory cytokines (IL-1 and TNF-α). To conclude, n-3-PUFA supplementation appears to represent a promising nutraceutical approach for the restoration of abnormalities in liver lipid metabolism and the prevention and treatment of NAFLD.
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Affiliation(s)
- Václav Šmíd
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic (R.B.); (L.V.)
| | - Karel Dvořák
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic (R.B.); (L.V.)
| | - Kamila Stehnová
- Department of Food Analysis and Nutrition, University of Chemistry and Technology, 166 28 Prague, Czech Republic; (K.S.); (J.R.); (J.H.)
| | - Hynek Strnad
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Josep Rubert
- Department of Food Analysis and Nutrition, University of Chemistry and Technology, 166 28 Prague, Czech Republic; (K.S.); (J.R.); (J.H.)
| | - Jan Stříteský
- Institute of Pathology, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 00 Prague, Czech Republic;
| | - Barbora Staňková
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic (R.B.); (L.V.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic
| | - Milena Stránská
- Department of Food Analysis and Nutrition, University of Chemistry and Technology, 166 28 Prague, Czech Republic; (K.S.); (J.R.); (J.H.)
| | - Jana Hajšlová
- Department of Food Analysis and Nutrition, University of Chemistry and Technology, 166 28 Prague, Czech Republic; (K.S.); (J.R.); (J.H.)
| | - Radan Brůha
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic (R.B.); (L.V.)
| | - Libor Vítek
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic (R.B.); (L.V.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague and General University Hospital, 128 08 Prague, Czech Republic
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Ravaszová S, Dvořák K, Vaičiukynienė D, Sisol M. Application of a Method for Measuring the Grindability of Fine-Grained Materials by High-Speed Milling. Materials (Basel) 2022; 15:8085. [PMID: 36431568 PMCID: PMC9695657 DOI: 10.3390/ma15228085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 06/16/2023]
Abstract
This article deals with the development of an alternative method for determining the grindability index of fine-grained materials. This method is inspired by the commercially used VTI method (also known as RTI after the Russian Thermal Energy Institute), which was widely used in Central and Eastern Europe in coal grinding. The disadvantage of the VTI method is that it uses a specific grinding device that otherwise has no other use and nowadays is no longer commonly available. Through the new method, high-energy grinding was performed using a commercially available planetary mill on silicate materials such as limestone, feldspar, corundum, and quartz. The effectiveness of the method was verified on clinker as a representative of widely used materials. The deviation between the grindability index calculated by the origin VTI method and the new developed method was on average approximately 8%; in the case of clinker grinding, it was only 3%. The results showed that the VTI method could be replaced by a new method that uses a modern available planetary mill and laser granulometry to determine the grindability index. The result is a new classification of materials according to their grindability indexes, which is based on the original VTI method.
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Affiliation(s)
- Simona Ravaszová
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic
| | - Karel Dvořák
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic
| | - Danute Vaičiukynienė
- Faculty of Civil Engineering and Architecture, Kaunas University of Technology, Studentu St. 48, LT513-67 Kaunas, Lithuania
| | - Martin Sisol
- Faculty of Mining, Ecology, Process Control and Geotechnologies, Technical University of Košice, Letna 9, 042 00 Košice, Slovakia
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Šmíd V, Dvořák K, Šedivý P, Kosek V, Leníček M, Dezortová M, Hajšlová J, Hájek M, Vítek L, Bechyňská K, Brůha R. Effect of Omega-3 Polyunsaturated Fatty Acids on Lipid Metabolism in Patients With Metabolic Syndrome and NAFLD. Hepatol Commun 2022; 6:1336-1349. [PMID: 35147302 PMCID: PMC9134818 DOI: 10.1002/hep4.1906] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 01/06/2022] [Accepted: 01/21/2022] [Indexed: 12/15/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. n-3 polyunsaturated fatty acids (n-3-PUFAs) have been reported to ameliorate the progression of NAFLD in experimental studies; however, clinical trials have yielded contradictory results. The aim of our study was to assess the effects of n-3-PUFA administration on lipid metabolism and the progression of NAFLD in patients with metabolic syndrome. Sixty patients with metabolic syndrome and NAFLD were randomized in a double-blind placebo-controlled trial (3.6 g/day n-3-PUFA vs. placebo). During the 1-year follow-up, the patients underwent periodic clinical and laboratory examinations, liver stiffness measurements, magnetic resonance spectroscopy of the liver, and plasma lipidomic analyses. After 12 months of n-3-PUFA administration, a significant decrease in serum GGT activity was recorded compared with the placebo group (2.03 ± 2.8 vs. 1.43 ± 1.6; P < 0.05). Although no significant changes in anthropometric parameters were recorded, a significant correlation between the reduction of liver fat after 12 months of treatment-and weight reduction-was observed; furthermore, this effect was clearly potentiated by n-3-PUFA treatment (P < 0.005). In addition, n-3-PUFA treatment resulted in substantial changes in the plasma lipidome, with n-3-PUFA-enriched triacylglycerols and phospholipids being the most expressed lipid signatures. Conclusion: Twelve months of n-3-PUFA treatment of patients with NAFLD patients was associated with a significant decrease in GGT activity, the liver fat reduction in those who reduced their weight, and beneficial changes in the plasma lipid profile.
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Affiliation(s)
- Václav Šmíd
- Fourth Department of Internal MedicineFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
| | - Karel Dvořák
- Fourth Department of Internal MedicineFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
| | - Petr Šedivý
- Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental MedicinePragueCzech Republic
| | - Vít Kosek
- Department of Food Analysis and NutritionUniversity of Chemistry and TechnologyPragueCzech Republic
| | - Martin Leníček
- Institute of Medical Biochemistry and Laboratory DiagnosticsFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
| | - Monika Dezortová
- Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental MedicinePragueCzech Republic
| | - Jana Hajšlová
- Department of Food Analysis and NutritionUniversity of Chemistry and TechnologyPragueCzech Republic
| | - Milan Hájek
- Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental MedicinePragueCzech Republic
| | - Libor Vítek
- Fourth Department of Internal MedicineFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
- Institute of Medical Biochemistry and Laboratory DiagnosticsFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
| | - Kamila Bechyňská
- Department of Food Analysis and NutritionUniversity of Chemistry and TechnologyPragueCzech Republic
| | - Radan Brůha
- Fourth Department of Internal MedicineFirst Faculty of Medicine and General University Hospital in PragueCharles UniversityPragueCzech Republic
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Dvořák K, Šmíd V. An overview of current therapy options of non-alcoholic fatty liver disease. Cas Lek Cesk 2022; 161:77-79. [PMID: 35728962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Finding an effective treatment of non-alcoholic fatty liver disease (NAFLD) remains one of main challenges in hepatological research for the 21st century, since there is no such a treatment yet. Lifestyle modifications leading to weight reduction are cheap and effective, however only a fraction of patients reaches significant weight loss goals. Current pharmacological treatment of NAFLD comprises screening and therapy of metabolic syndrome components and minimizing of alcohol intake. There are new substances being evaluated in clinical trials, the most promising ones are semaglutide and lanifibranor.
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Dvořák K, Falt P, Paterová P, Šembera Š, Šenkyřík M, Cyrany J. A cirrhotic patient in an internal medicine ward. Vnitr Lek 2022; 68:19-25. [PMID: 35459343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Liver cirrhosis represents a common condition with substantial mortality. Manifestation and progression of ascites, hepatic encephalopathy or gastrointestinal bleeding are among main reasons for hospital admission. Infections represent another specific area in cirrhotic patients. Timely and correct diagnosis and therapy of these conditions are the mainstay of optimal outcome. Manifestation of complications of liver cirrhosis significantly deteriorates prognosis of the patient. Ascites in portal hypertension develops as a result of sodium and consequently water retention. Therapy comprises of restriction of sodium intake, diuretic therapy with combination of spironolactone and furosemide, alternatively large-volume paracentesis. Hepatic encephalopathy comprises a spectrum of neuropsychiatric abnormalities from subtle changes to overt desorientation and asterixis to hepatic coma. Treatment includes correcting of predisposing conditions, administering of non-absorbable disaccharides or rifaximin. The most common cause of bleeding in a cirrhotic patient is oesophageal bleeding. Therapy is complex including hemodynamic stabilisation, antibiotic prophylaxis, vasoactive and endoscopic treatment. Infections are common causes of decompensation and occurrence of complications of advanced chronic liver disease. Their unfavourable outcome is a result of a complex immune disorder in cirrhotic patients. Specific type of infection in cirrhosis is spontaneous bacterial peritonitis, which has to be always excluded with diagnostic paracentesis. The mainstay of successful therapy of infections is timely and vigorous broad spectrum antibiotic therapy which can significantly improve otherwise unfavourable outcome of these patients.
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Dvořák K. Diagnostic methods of fatty liver diseases. Cas Lek Cesk 2022; 161:57-60. [PMID: 35728958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Fatty liver diseases represent the most common chronic liver diseases today. Therefore, the diagnostics of fatty liver is of great importance. Sonography is the most used imaging method in daily clinical practice for its availability and good diagnostic performance. But there are limitations in lower sensitivity in mild steatosis and in subjects with more severe obesity. Sonographic findings of fatty liver include higher echogenity of liver parenchyma and attenuation of ultrasound waves in deeper parts of the liver. Furthermore, there are some other advanced methods for semiquantitative and quantitative assessment of the amount of the liver fat. Many of them are based on acoustic signal attenuation assessment. The most broadly used is a CAP (controlled attenuation parameter) feature of FibroScan, which can assess fatty liver without classic ultrasound examination. Thera are also special MR based techniques - MR spectroscopy and PDFF (protein density fat fraction) which allow liver fat quantification with high precision and can be used as a reference standard.
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Petrtýl J, Dvořák K, Stříteský J, Leníček M, Jirásková A, Šmíd V, Haluzík M, Brůha R, Vítek L. Association of Serum Bilirubin and Functional Variants of Heme Oxygenase 1 and Bilirubin UDP-Glucuronosyl Transferase Genes in Czech Adult Patients with Non-Alcoholic Fatty Liver Disease. Antioxidants (Basel) 2021; 10:antiox10122000. [PMID: 34943103 PMCID: PMC8698489 DOI: 10.3390/antiox10122000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 12/29/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder worldwide. The aim of our study was to assess the role of bilirubin, and the heme oxygenase 1 (HMOX1) and bilirubin UDP-glucuronosyl transferase (UGT1A1) promoter gene variants, which are involved in bilirubin homeostasis, in the NAFLD development in adult patients. The study was performed on 84 patients with NAFLD and 103 age/sex-matched controls. Routine biochemistry, inflammatory markers, adipokines, and the fibrosis/steatohepatitis stage were determined in the NAFLD patients. The (GT)n/(TA)n dinucleotide variations in HMOX1/UGT1A1 gene promoters, respectively, were analyzed by fragment analysis. Compared to controls, serum bilirubin concentrations in NAFLD patients tended to be decreased, while the prevalence of phenotypic Gilbert syndrome was significantly low. Genetic variations in HMOX1 and UGT1A1 gene promoters did not differ between NAFLD patients and controls, and no relationship was found in the NAFLD patients between these gene variants and any of the laboratory or histological parameters. In conclusion, metabolism of bilirubin is dysregulated in NAFLD patients, most likely due to increased oxidative stress, since frequencies of the major functional variants in the HMOX1 or UGT1A1 gene promoters did not have any effect on development of NAFLD in adult patients.
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Affiliation(s)
- Jaromír Petrtýl
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (J.P.); (K.D.); (V.Š.)
| | - Karel Dvořák
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (J.P.); (K.D.); (V.Š.)
| | - Jan Stříteský
- Institute of Pathology, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic;
| | - Martin Leníček
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (M.L.); (A.J.); (M.H.)
| | - Alena Jirásková
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (M.L.); (A.J.); (M.H.)
| | - Václav Šmíd
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (J.P.); (K.D.); (V.Š.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (M.L.); (A.J.); (M.H.)
| | - Martin Haluzík
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (M.L.); (A.J.); (M.H.)
- Institute of Clinical and Experimental Medicine, 140 00 Prague, Czech Republic
| | - Radan Brůha
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (J.P.); (K.D.); (V.Š.)
- Correspondence: (R.B.); (L.V.); Tel.: +420-224-962-506 (R.B.); +420-224-964-203 (L.V.)
| | - Libor Vítek
- 4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (J.P.); (K.D.); (V.Š.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, 120 00 Prague, Czech Republic; (M.L.); (A.J.); (M.H.)
- Correspondence: (R.B.); (L.V.); Tel.: +420-224-962-506 (R.B.); +420-224-964-203 (L.V.)
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Kunčická L, Jopek M, Kocich R, Dvořák K. Determining Johnson-Cook Constitutive Equation for Low-Carbon Steel via Taylor Anvil Test. Materials (Basel) 2021; 14:ma14174821. [PMID: 34500907 PMCID: PMC8432488 DOI: 10.3390/ma14174821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 11/16/2022]
Abstract
Tristal steel is low-carbon construction-type steel widely used in the automotive industry, e.g., for braking components. Given the contemporary demands on the high-volume production of such components, these are typically fabricated using automatic sequential machines, which can produce components at strain rates up to 103 s−1. For this reason, characterising the behaviour of the used material at high strain rates is of the utmost importance for successful industrial production. This study focuses on the characterisation of the behaviour of low-carbon steel via developing its material model using the Johnson-Cook constitutive equation. At first, the Taylor anvil test is performed. Subsequently, the acquired data together with the results of observations of structures and properties of the tested specimens are used to fill the necessary parameters into the equation. Finally, the developed equation is used to numerically simulate the Taylor anvil test and the predicted data is correlated with the experimentally acquired one. The results showed a satisfactory correlation of the experimental and predicted data; the deformed specimen region featured increased occurrence of dislocations, as well as higher hardness (its original value of 88 HV increased to more than 200 HV after testing), which corresponded to the predicted distributions of effective imposed strain and compressive stress.
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Affiliation(s)
- Lenka Kunčická
- Institute of Physics of Materials, Czech Academy of Sciences, Žižkova 22, 616 00 Brno, Czech Republic
- Correspondence: ; Tel.: +420-532-290-371
| | - Miroslav Jopek
- Department of Metal Forming and Plastic, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic;
| | - Radim Kocich
- Faculty of Materials Science and Technology, VŠB–Technical University of Ostrava, 708 00 Ostrava, Czech Republic;
| | - Karel Dvořák
- Faculty of Civil Engineering, Institute of Technology of Building Materials and Components, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic;
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Vaičiukynienė D, Jakevičius L, Kantautas A, Vaitkevičius V, Vaičiukynas V, Dvořák K. Conversion of silica by-product into zeolites by thermo-sonochemical treatment. Ultrason Sonochem 2021; 72:105426. [PMID: 33383545 PMCID: PMC7803841 DOI: 10.1016/j.ultsonch.2020.105426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 05/10/2023]
Abstract
The fine powdered silica by-product of processing of aluminum fluoride (fertilizer plant, Lithuania) was used for zeolite synthesis as silica and aluminum source. The effect of sonication time and the time of hydrothermal synthesis on crystallinity of the synthesized zeolite were studied. This allowed the transformation of the by-product to the mixture of Na-P zeolite and Na-X zeolite. It was determined that ultrasonic-assisted hydrothermal action effected the "diamond" shape formation of Na-P zeolite with clear crystal edges. Na-P zeolite had the morphology of pseudo-spherical forms constituted by small plates when hydrothermal treatment (without sonication) was use for the preparation of zeolites. Moreover, it was determined that ultrasonic-assisted hydrothermal method effected a reduction in the crystal size compared with the zeolites which were synthesized only by using hydrothermal synthesis. The total amount of zeolites as high as 88-93% was achieved after 24 h of hydrothermal treatment followed or unfollowed by sonication. By using longer duration (20 min) of ultrasound pretreatment it is possible to reduce the duration of hydrothermal synthesis: from 24 h to 12 h of hydrothermal treatment. In this case, similar results of total amount of zeolites were detected. In the present work, low-cost raw materials, such as silica by-product have been investigated for the production of zeolites.
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Affiliation(s)
- Danutė Vaičiukynienė
- Kaunas University of Technology, Faculty of Civil Engineering and Architecture, Studentų g. 48, Kaunas 44249, Lithuania.
| | - Leonas Jakevičius
- Kaunas University of Technology, Faculty of Mathematics and Natural Sciences, Studentų g. 52, Kaunas 44249, Lithuania
| | - Aras Kantautas
- Kaunas University of Technology, Faculty of Civil Engineering and Architecture, Studentų g. 48, Kaunas 44249, Lithuania
| | - Vitoldas Vaitkevičius
- Kaunas University of Technology, Faculty of Civil Engineering and Architecture, Studentų g. 48, Kaunas 44249, Lithuania
| | - Vilimantas Vaičiukynas
- Brno University of Technology, Faculty of Civil Engineering, Veveří 512/95, Brno 602 00, Czechia
| | - Karel Dvořák
- Vytautas Magnus University, Faculty of Water and Land Management Agriculture Academy, Universiteto g. 10, Akademija 53361, Lithuania
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Zemánek D, Lang K, Tvrdík L, Všianský D, Nevřivová L, Štursa P, Kovář P, Keršnerová L, Dvořák K. Development and Properties of New Mullite Based Refractory Grog. Materials (Basel) 2021; 14:ma14040779. [PMID: 33562214 PMCID: PMC7915343 DOI: 10.3390/ma14040779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/25/2022]
Abstract
The presented study is focused on optimization and characterization of a high-alumina refractory aggregate based on natural raw materials—kaolins, claystone, and mullite dust by-product (used to increase the alumina and mullite contents, respectively). In total, four individual formulas with the Al2O3 contents between 45 and 50 wt.% were designed; the samples were subsequently fired, both in a laboratory oven and an industrial tunnel furnace. The effects of repeated firing were examined during industrial pilot tests. Mineral and chemical compositions and microstructures, of both the raw materials and designed aggregates, were thoroughly investigated by the means of X-ray fluorescence spectroscopy, powder X-ray diffraction, and optical and scanning electron microscopies. Porosity, mineral composition, and mullite crystal-size development during the firing process were also studied. Based on the acquired results, the formula with the perspective to be used as a new mullite grog, featuring similar properties as the available commercial products, however, with reduced production expenses, was selected. The quality of grog determines to a large extent the properties of the final product. Hence, optimization of aggregates for specific refractories is of a great importance. The production of engineered aggregates provides the opportunity to utilize industrial by-products.
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Affiliation(s)
- David Zemánek
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (D.Z.); (L.N.)
- P-D Refractories CZ JSC, Nádražní 218, 679 63 Velké Opatovice, Czech Republic; (K.L.); (L.T.); (P.Š.)
| | - Karel Lang
- P-D Refractories CZ JSC, Nádražní 218, 679 63 Velké Opatovice, Czech Republic; (K.L.); (L.T.); (P.Š.)
| | - Lukáš Tvrdík
- P-D Refractories CZ JSC, Nádražní 218, 679 63 Velké Opatovice, Czech Republic; (K.L.); (L.T.); (P.Š.)
| | - Dalibor Všianský
- Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 267/2, 602 00 Brno, Czech Republic; (D.V.); (P.K.); (L.K.)
| | - Lenka Nevřivová
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (D.Z.); (L.N.)
- P-D Refractories CZ JSC, Nádražní 218, 679 63 Velké Opatovice, Czech Republic; (K.L.); (L.T.); (P.Š.)
| | - Petr Štursa
- P-D Refractories CZ JSC, Nádražní 218, 679 63 Velké Opatovice, Czech Republic; (K.L.); (L.T.); (P.Š.)
- Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 267/2, 602 00 Brno, Czech Republic; (D.V.); (P.K.); (L.K.)
| | - Pavel Kovář
- Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 267/2, 602 00 Brno, Czech Republic; (D.V.); (P.K.); (L.K.)
| | - Lucie Keršnerová
- Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 267/2, 602 00 Brno, Czech Republic; (D.V.); (P.K.); (L.K.)
| | - Karel Dvořák
- Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, 602 00 Brno, Czech Republic; (D.Z.); (L.N.)
- Correspondence: ; Tel.: +420-54114-7511 (ext. 8067)
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Ravaszová S, Dvořák K. Development of Crystallinity of Triclinic Polymorph of Tricalcium Silicate. Materials (Basel) 2020; 13:ma13173734. [PMID: 32847001 PMCID: PMC7504084 DOI: 10.3390/ma13173734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/17/2020] [Accepted: 08/20/2020] [Indexed: 11/16/2022]
Abstract
Tricalcium silicate phase is one of the main components of modern Portland cements. One of the major industrial challenges in the field of cement production is mapping the influence of individual clinker minerals and their polymorphs on the properties of industrially produced clinkers. The primary goal of this work is to improve the fundamental knowledge of understanding the process of alite formation and development from a crystallographic point of view. This study focuses on the observation of the crystallization process of triclinic alite during the firing process, which to date has not been thoroughly described. The effects of a wide range of temperatures and sintering periods on crystallinity were assessed on samples fired in platinum crucibles in a laboratory furnace. X-ray analysis-together with calculation of crystallinity using Scherrer's equation-was used for observing the crystallite size changes of T1 alite polymorph. According to the acquired results, among the most technologically and economically advantageous regimes of production of a high-quality triclinic alite is the temperature of 1450 °C and sintering time of two hours. The most significant changes in the crystallite size occurred within the first hour of sintering for the whole investigated temperature range.
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Dvořák K. Noninvasive diagnostics of liver diseases - imaging methods. Vnitr Lek 2019; 65:539-545. [PMID: 31635464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Introduction and spread of elastographical methods have changed clinical practice in hepatology substantially. Elastography is becoming more available and the field of non-invasive diagnostics of liver diseases keeps growing dynamically. New technologies and applications are being developed allowing non-invasive staging of liver diseases to much broader extent. Ultrasound based methods like transient elastography (TE) and shear wave elasto-graphy (SWE) are dominating the field of liver elastography. Both methods are able to distinguish advanced liver fibrosis/cirrhosis with high accuracy and in patients with all most common chronic liver diseases. A technically well performed examination and its interpretation in a clinical context are prerequisites for a valid diagnosis. TE also enables assessment of presence/severity of portal hypertension in patients with compensated chronic advanced liver disease. There are new methods under development and validation like an ultrasound-based liver fat content quantification, assessment of portal hypertension using elastography of the spleen or the use of elastography in the diagnostics of focal liver lesions.
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Montufar E, Casas-Luna M, Horynová M, Tkachenko S, Fohlerová Z, Diaz-de-la-Torre S, Dvořák K, Čelko L, Kaiser J. High strength, biodegradable and cytocompatible alpha tricalcium phosphate-iron composites for temporal reduction of bone fractures. Acta Biomater 2018; 70:293-303. [PMID: 29432984 DOI: 10.1016/j.actbio.2018.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/13/2017] [Accepted: 02/01/2018] [Indexed: 11/25/2022]
Abstract
In this work alpha tricalcium phosphate (α-TCP)/iron (Fe) composites were developed as a new family of biodegradable, load-bearing and cytocompatible materials. The composites with composition from pure ceramic to pure metallic samples were consolidated by pulsed electric current assisted sintering to minimise processing time and temperature while improving their mechanical performance. The mechanical strength of the composites was increased and controlled with the Fe content, passing from brittle to ductile failure. In particular, the addition of 25 vol% of Fe produced a ceramic matrix composite with elastic modulus much closer to cortical bone than that of titanium or biodegradable magnesium alloys and specific compressive strength above that of stainless steel, chromium-cobalt alloys and pure titanium, currently used in clinic for internal fracture fixation. All the composites studied exhibited higher degradation rate than their individual components, presenting values around 200 μm/year, but also their compressive strength did not show a significant reduction in the period required for bone fracture consolidation. Composites showed preferential degradation of α-TCP areas rather than β-TCP areas, suggesting that α-TCP can produce composites with higher degradation rate. The composites were cytocompatible both in indirect and direct contact with bone cells. Osteoblast-like cells attached and spread on the surface of the composites, presenting proliferation rate similar to cells on tissue culture-grade polystyrene and they showed alkaline phosphatase activity. Therefore, this new family of composites is a potential alternative to produce implants for temporal reduction of bone fractures. STATEMENT OF SIGNIFICANCE Biodegradable alpha-tricalcium phosphate/iron (α-TCP/Fe) composites are promising candidates for the fabrication of temporal osteosynthesis devices. Similar to biodegradable metals, these composites can avoid implant removal after bone fracture healing, particularly in young patients. In this work, α-TCP/Fe composites are studied for the first time in a wide range of compositions, showing not only higher degradation rate in vitro than pure components, but also good cytocompatibility and mechanical properties controllable with the Fe content. Ceramic matrix composites show high specific strength and low elastic modulus, thus better fulfilling the requirements for bone fractures fixation. A significant advance over previous works on the topic is the use of pulsed electric current assisted sintering together with α-TCP, convenient to improve the mechanical performance and degradation rate, respectively.
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Tkachenko S, Horynová M, Casas-Luna M, Diaz-de-la-Torre S, Dvořák K, Celko L, Kaiser J, Montufar EB. Strength and fracture mechanism of iron reinforced tricalcium phosphate cermet fabricated by spark plasma sintering. J Mech Behav Biomed Mater 2018; 81:16-25. [PMID: 29477027 DOI: 10.1016/j.jmbbm.2018.02.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/09/2018] [Accepted: 02/12/2018] [Indexed: 11/28/2022]
Abstract
The present work studies the microstructure and mechanical performance of tricalcium phosphate (TCP) based cermet toughened by iron particles. A novelty arises by the employment of spark plasma sintering for fabrication of the cermet. Results showed partial transformation of initial alpha TCP matrix to beta phase and the absence of oxidation of iron particles, as well as a lack of chemical reaction between TCP and iron components during sintering. The values of compressive and tensile strength of TCP/Fe cermet were 3.2 and 2.5 times, respectively, greater than those of monolithic TCP. Fracture analysis revealed the simultaneous action of crack-bridging and crack-deflection microstructural toughening mechanisms under compression. In contrast, under tension the reinforcing mechanism was only crack-bridging, being the reason for smaller increment of strength. Elastic properties of the cermet better matched values reported for human cortical bone. Thereby the new TCP/Fe cermet has potential for eventual use as a material for bone fractures fixation under load-bearing conditions.
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Affiliation(s)
- Serhii Tkachenko
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Miroslava Horynová
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Mariano Casas-Luna
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Sebastian Diaz-de-la-Torre
- CIITEC - Centro de Investigación e Innovación Tecnológica, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Karel Dvořák
- Faculty of Civil Engineering, Brno University of Technology, Brno, Czech Republic
| | - Ladislav Celko
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Jozef Kaiser
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Edgar B Montufar
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic.
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Brůha R, Dvořák K, Petrtýl J. [Liver disorders in diabetic patients]. Vnitr Lek 2013; 59:546-550. [PMID: 23909257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
There is a mutual relationship between diabetes and liver disorders. Diabetic patients suffer from liver disorders more frequently and, vice versa, patients with liver disorders are at a higher risk of developing diabetes. Diabetes is probably the most common cause of chronic liver disorders in developed countries. Liver disorders related to diabetes include a wide spectrum of conditions, from a simple steatosis related to a slight elevation of liver tests through nonalcoholic steatohepatitis with various degrees of fibrosis up to cirrhosis, hepatocellular carcinoma and acute liver failure. Non alcoholic liver steatosis is the most common pathological condition that is, at present, considered to be a component of or to actually be the liver manifestation of metabolic syndrome, accompanied with an insulin resistance and other clinical components, such as central obesity, dyslipidemia, arterial hypertension and the already mentioned type 2 diabetes mellitus. The steatosis itself is a benign condition and the unfavourable development of the liver disorder is related to an inflammatory reaction (steatohepatitis) and subsequent fibrosis. There is no specific treatment for nonalcoholic steatohepatitis. The basic measures include weight reduction, lifestyle changes and treatment of the concurrent conditions, such as diabetes and dyslipidemia. Formerly popular "hepatoprotective" substances do not play an important role in the treatment of steatohepatitis.
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Affiliation(s)
- R Brůha
- IV. interní klinika 1. lékařské fakulty UK a VFVN Praha.
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Lukáš K, Dvořák K, Novotný A, Hejdová H, Mišutková J. [Differential diagnosis of the ileum diseases]. Cas Lek Cesk 2013; 152:4-14. [PMID: 23448671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Inflammation of the ileum - ileitis - is classically connected with Crohn's disease. But a wide variety of diseases is associated with inflammation of the ileum. These include inflammatory bowel disease, infections, spondyloarthropathies, vascular diseases, drug-related enteritis, infiltration (e.g. sarcoidosis, amyloidosis), postirradiation enteritis, tumors, endometriosis, celiac disease and collagenosis.
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Dvořák K, Buček J. Postnatal differentiation of the Golgi apparatus and the dendrites of Purkinje cells of the rat cerebellum. Cell Tissue Res 1970. [DOI: 10.1007/bf00342100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Radochová D, Chrobák L, Šmíd A, Dvořák K. Der Anteil der Hämolyse an der Anämie nach Anwendung der Herz-Lungen-Maschine. Thorac Cardiovasc Surg 1967. [DOI: 10.1055/s-0028-1100617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Dvořák K, Boublík T. Liquid-vapour equilibria. XXIX. Measurement of equilibrium data in systems with high equilibrium ratio of the components. ACTA ACUST UNITED AC 1963. [DOI: 10.1135/cccc19631249] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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