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Statistical Analysis of Delayed Payments of Company FAVEX, s.r.o.
Zach, Jakub ; Chovanec, Martin (referee) ; Kropáč, Jiří (advisor)
This bachelor thesis focuses on the analysis of delay in payment of invoices, amount of overdue invoices and relation between these two variables. The analysis is performed using statistical methods of one-dimensional and two-dimensional data set and time series. This bachelor thesis includes not only the used theoretical background, but also the use of theoretical knowledge in practice.
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Modification of soda lignin isolated from winery waste
Chovanec, Martin ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis provides research on the antibacterial activity of lignin isolated from grape pomace. To separate lignin from grape pomace was used soda lignin isolation method. This method helps to dissolve lignin in the solution of sodium hydroxide. Two isolation procedures were used: 1) isolation by using a conventional laboratory set-up at atmospheric pressure and a temperature of 110 °C and 2) isolation by using a hydrothermal autoclave at increased pressure and a temperature of 110 °C. The hydrothermal autoclave was explicitly developed for this bachelor thesis. Both separations methods were compared from the viewpoint of lignin yields and lignin purity. The lignin yield obtained by using the hydrothermal autoclave was much higher compared to the conventional laboratory set-up, yielding about 36.4 g of soda lignin per 100 g of grape pomace. The infrared spectroscopy analysis of both lignins showed that lignin received by using the conventional laboratory set-up was mixed with hemicelluloses and cellulose. The isolation by using the hydrothermal autoclave enabled to prepare lignin with higher purity. Lignin isolated from grape pomace did not show any antimicrobial activity. The antimicrobial activity was reached after modification of lignin with silver particles in situ. Antimicrobial activity was tested against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Serratia marcescens, Saccharomyces cerevisiae and Candida glabrata. The lignin/silver compound showed the antibacterial activity against all tested bacteria, however no antimicrobial activity against yeasts.
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Functional technical materials modified by lignin isolated from winery by-products
Chovanec, Martin ; Sedláček, Petr (referee) ; Kovalčík, Adriána (advisor)
In this thesis, the possibility of producing composites of epoxy resin and lignin isolated from grape skins was examined. The motivation was to reduce the amount of bisphenol A, which is nowadays used to produce most of the epoxy resins and is the main environmental pollutant. The composites were prepared by mixing commercial bisphenol A diglycidylether (DGEBA) with lignin samples. In this work, the sodium hydroxide pulping method in a hydrothermal autoclave was used to isolate lignin. The content of reducing sugars, lignin, and fatty acids in the sample of grape skins was determined and the chemical composition was determined by Fourier transform infrared spectroscopy (FT-IR). The chemical and thermal properties of isolated soda lignin were compared with commercial Kraft lignin and analyzed by elemental analysis, FT-IR, thermogravimetric analysis, and ash content determination. Epoxidized lignin was prepared by three methods, which were compared based on yield, epoxide equivalent, and chemical composition. Samples of unmodified soda lignin and epoxidized soda and Kraft lignins were selected for the preparation of epoxy composites. Experiments have shown that isolated soda lignin was not suitable for the addition to epoxy resins, unlike Kraft lignin. Thermal and viscoelastic properties of the prepared composites with a homogeneous structure were analyzed. It was found that the epoxy composites with added epoxidized Kraft lignin showed lower material stiffness and the glass transition temperature was significantly shifted to lower temperatures.
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New methods of classification and prognosis in paragangliomas and pheochromocytomas
Guha, Anasuya ; Chovanec, Martin (advisor) ; Stárek, Ivo (referee) ; Bouček, Jan (referee)
Pheochromocytomas and paragangliomas are rare, mostly benign neuroendocrine tumors. Head and neck paragangliomas (HNPGLs) are extra-adrenal counterparts of pheochromocytomas, representing 3% of all head and neck tumors. These can occur as sporadic tumors or as part of a hereditary syndromes. Studies reporting HNPGLs in Czech Republic have been limited. We conducted a systematic review to ascertain gene mutations that are directly linked to HNPGLs. We also studied the phenotypic-genotypic profiles as well as treatment outcomes of HNPGLs. Genetic analysis was performed in Czech Republic and in collaboration with Bethesda, USA. Our review showed that ten genes contribute to the development of HNPGLs when mutated. Familial forms of the disease are most commonly associated with the SDHD gene. SDHB mutations are predisposed to malignant tumors. We assessed 30 patients (11 males; 19 females) of 34-80 years of age at our clinic between 2016 and 2021. Amongst all patients, 24 had solitary tumors and 6 showed multiple tumors. Jugular paragangliomas were the most frequently diagnosed HNPGL. Only 11.5% of all examined patients were positive for SDHD germline mutation; 50% of our younger patients with bilateral carotid body tumors had the SDHD mutation. Four patients with negative family history were diagnosed...
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Functional technical materials modified by lignin isolated from winery by-products
Chovanec, Martin ; Sedláček, Petr (referee) ; Kovalčík, Adriána (advisor)
In this thesis, the possibility of producing composites of epoxy resin and lignin isolated from grape skins was examined. The motivation was to reduce the amount of bisphenol A, which is nowadays used to produce most of the epoxy resins and is the main environmental pollutant. The composites were prepared by mixing commercial bisphenol A diglycidylether (DGEBA) with lignin samples. In this work, the sodium hydroxide pulping method in a hydrothermal autoclave was used to isolate lignin. The content of reducing sugars, lignin, and fatty acids in the sample of grape skins was determined and the chemical composition was determined by Fourier transform infrared spectroscopy (FT-IR). The chemical and thermal properties of isolated soda lignin were compared with commercial Kraft lignin and analyzed by elemental analysis, FT-IR, thermogravimetric analysis, and ash content determination. Epoxidized lignin was prepared by three methods, which were compared based on yield, epoxide equivalent, and chemical composition. Samples of unmodified soda lignin and epoxidized soda and Kraft lignins were selected for the preparation of epoxy composites. Experiments have shown that isolated soda lignin was not suitable for the addition to epoxy resins, unlike Kraft lignin. Thermal and viscoelastic properties of the prepared composites with a homogeneous structure were analyzed. It was found that the epoxy composites with added epoxidized Kraft lignin showed lower material stiffness and the glass transition temperature was significantly shifted to lower temperatures.
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The evaluation of vestibulospinal and vestibuloocular reflex in patients during early postoperative period after vestibular schwannoma resection
Markvartová, Anna ; Čakrt, Ondřej (advisor) ; Chovanec, Martin (referee)
The thesis deals with the issues of balance disorders in patients after vestibular schwannoma surgery. The aim of this thesis is to evaluate the effect of targeted rehabilitation with biofeedback on balance disorders and subjective visual vertical compensation. During the period of one year, a group of 20 vestibular schwannoma patients were examined and treated in University Hospital Motol. The compensation of vestbuloocular refex was assessed by a tilt of subjective visual vertical. The level of vestibulospinal compensation was determined according to score of the Activities-Specific Balance Confidence Scale. Patients were examined before the surgery, after the surgery and after the rehabilitation. The Homebalance system, developed by Support center for application outputs and spin-off companies at the 1st Faculty of Medicine, Charles University in Prague, branch office in Kladno, was used for the therapy with visual biofeedback. Another aim of this thesis was to monitor the effect of vestibular prehabituation with ototoxic gentamicin application two months before surgery. The statistical analysis of data proved in the case of subjective visual vertical tilt a significant increase of deviation after surgery and a decrease after rehabilitation. According to the ABC questionnaire the confidence of...
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Quality of life in patients after vestibular Schwannoma surgery
Hajná, Barbora ; Čakrt, Ondřej (advisor) ; Chovanec, Martin (referee)
TVestibular schwannoma is a benign tumor that arises from the Schwann cells of the vestibular nerve. Unilateral hearing loss, tinnitus, facial and trigeminal dysfunction and vertigo are the most common symptoms. Surgical removal of the tumor is one of the treatment modalities of this disease. Surgical excision usually involves the complete vestibular nerve resection and there is also a risk of cochlear and facial nerve lesion. This thesis deals with changes in quality of life in patients after vestibular schwannoma sugery, which are associated with balance deficits, tinnitus and facial palsy.
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The influence of unilateral vestibular dysfunction on spatial orientation in patients after vestibular schwannoma surgery
Šponarová, Lenka ; Čakrt, Ondřej (advisor) ; Chovanec, Martin (referee)
The aim of this diploma thesis is to evaluate spatial orientation in the patients after vestibular schwannoma surgery. In the theoretical part, there are summarized the facts about vestibular system; there is described the clinical picture of unilateral vestibular dysfunction and the field of vestibular schwannoma and spatial orientation in general. In the practical part, we performed the investigation of the spatial orientation using the Blue Velvet Arena System and posturography using the platform Balance Master® System. The purpose of the practical part was to find out, whether unilateral vestibular dysfunction in patients after vestibular schwannoma surgery has the impact on spatial orientation and to what extent is the postural stability influenced in patients identified for surgery and in patients after vestibular schwannoma surgery. Powered by TCPDF (www.tcpdf.org)
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New trends in cell and molecular biology of the head and neck cancer
Fík, Zdeněk ; Chovanec, Martin (advisor) ; Komínek, Pavel (referee) ; Ludvíková, Marie (referee)
Head and neck squamous cell carcinomas are still challenging despite progress in the oncological treatment. Study of the molecular biology allows to deeply characterize tumor properties and to predict the prognosis for affected patients. Nowadays there are many drugs clinically tested in the group of targeted therapy medicine Experimental work comprised both in vitro and in situ assays, being performed thanks to the collaboration between a number of departments of the 1st Faculty of Medicine of the Charles University in Prague, Academy of Sciences of the Czech Republic, Institute of Hematology and Blood Transfusion and Faculty of Veterinary Medicine of the Ludwig-Maxmillian University Munich. Galectin-1 is important inductor of the myofibroblasts/cancer associated fibroblasts. These fibroblasts are regarded as negative prognostic markers thanks to their capability of invasive cancer cells induction. On the other hand, Galectin-9 is not present in the carcinoma and in the case of dysplasia, its expression indicate aberrant features together with aberrant expression of keratin 14 and 19. Except from galectins using as prognostic markers, we focused on the galectins as a therapeutics instruments as well. Presented work with mutant variants of galectin-2 proved their effect on both pharmacodynamics and...
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Modification of soda lignin isolated from winery waste
Chovanec, Martin ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis provides research on the antibacterial activity of lignin isolated from grape pomace. To separate lignin from grape pomace was used soda lignin isolation method. This method helps to dissolve lignin in the solution of sodium hydroxide. Two isolation procedures were used: 1) isolation by using a conventional laboratory set-up at atmospheric pressure and a temperature of 110 °C and 2) isolation by using a hydrothermal autoclave at increased pressure and a temperature of 110 °C. The hydrothermal autoclave was explicitly developed for this bachelor thesis. Both separations methods were compared from the viewpoint of lignin yields and lignin purity. The lignin yield obtained by using the hydrothermal autoclave was much higher compared to the conventional laboratory set-up, yielding about 36.4 g of soda lignin per 100 g of grape pomace. The infrared spectroscopy analysis of both lignins showed that lignin received by using the conventional laboratory set-up was mixed with hemicelluloses and cellulose. The isolation by using the hydrothermal autoclave enabled to prepare lignin with higher purity. Lignin isolated from grape pomace did not show any antimicrobial activity. The antimicrobial activity was reached after modification of lignin with silver particles in situ. Antimicrobial activity was tested against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Serratia marcescens, Saccharomyces cerevisiae and Candida glabrata. The lignin/silver compound showed the antibacterial activity against all tested bacteria, however no antimicrobial activity against yeasts.
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