Ustav Organicke Technology

Prague, Czech Republic

Ustav Organicke Technology

Prague, Czech Republic
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Vesela D.,Ustav organicke Technology | Dvorak B.,Ustav organicke Technology
Chemicke Listy | Year: 2016

The article gives a review on measurements of cobalt surface area (SgCo) by a method of dissociative hydrogen chemisorption which is a reversible process. It is therefore suitable to use techniques which enable one to determine amounts of both reversibly and irreversibly chemisorbed entities. This requirement is fulfilled with static techniques, the dynamic temperature desorption technique and the recently described technique of dynamic hydrogendeuterium exchange. The precision of the measurements is influenced by the following critically and systematically discussed factors: the extent of reduction to cobalt metal, the surface site density of cobalt atoms and their allotropic modification, the occurrence and stabilization conditions of high temperature face-centered-cubic cobalt under its transformation temperature t = 421.5 °C. © 2016, Czech Society of Chemical Engineering. All rights reserved.

Klusackova P.,Klinika Pracovniho Lekarstvi 1. LF UK A VFN | Lebedova J.,Klinika Pracovniho Lekarstvi 1. LF UK A VFN | Fenclova Z.,Klinika Pracovniho Lekarstvi 1. LF UK A VFN | Vlckova S.,Klinika Pracovniho Lekarstvi 1. LF UK A VFN | And 5 more authors.
Alergie | Year: 2013

Diagnostics of occupational asthma is based on positive results of bronchoprovocation tests (BPT) with occupational allergens. It is necessary to look for new methods which could make the diagnostics more precise. Twenty persons were tested with suspicion on occupational asthma. Except standard tests also leukotrienes (LT) B4, C4, D4, E 4, 8-isoprostane, malondialdehyde and 4-hydroxy-trans-2-nonenal in breath condensate, plasma and urine were analyzed. Examination was performed before BPT, after the non-specific bronchoprovocation test (nBPT) with methacholine and after specific bronchoprovocation tests with occupational allergens (sBPT). Specific bronchoprovocation tests were positive in 10 persons. In the group of patients with positive results of sBPT more frequently nBPT was positive (p = 0.002). Significant difference was found between groups with negative and positive results of sBPT in pH of breath condensate (p = 0.012). Within the group with positive sBPT significant decrease of 8-isoprostane was found in plasma after nBPT and sBPT (p = 0.006 a 0.049) compared to the basal value and significant increase of LTE4 in plasma after sBPT compared to the value after nBPT (p = 0.037).

Zdenkova R.,Ustav organicke Technology | Leitmannova-Vyskocilova E.,Ustav organicke Technology | Cerveny L.,Ustav organicke Technology
Chemicke Listy | Year: 2012

Methyltrioxorhenium is a homogenous catalyst used in many oxidation reactions and also in metathesis of olefins. This review deals with methyltrioxorhenium as a catalyst for olefin metathesis. The catalyst must be used in the heterogenized form in metathesis of functionalized olefins. That is the reason for studying the catalyst heterogenization. Deactivation and other uses of this catalyst were also studied.

Patera J.,Ustav Organicke Technology | Krupka J.,Ustav Organicke Technology | Paseka J.,Ustav Organicke Technology | Paterova I.,Ustav Organicke Technology | And 2 more authors.
Chemicke Listy | Year: 2012

An apparatus for dynamic chemisorption measurement was built and a reliable experimental methodology based on determination of the specific surface area of Pd (Spd) and the average particle size of Pd (dAV) in hydro-genation catalysts was developed using chemisorption of CO. Experimental conditions necessary for providing reproducibility of measured values were defined. The accuracy of the determination was verified by independent characterization techniques and by comparing chemisorption measurements of catalysts with the known characteristics. It was proved that the dAV of Pd in the catalysts containing 2-5 wt.% Pd on commercial supports (Al 2O3, active carbon, SiO2, Al2O 3-SiO2), obtained by chemisorption measurements are in a good agreement with the results of other methods, the stoichiometry of CO adsorption on Pd being 1:2.

On the occasion of 60 years anniversary of founding Institute of Chemical Technology as independent academic institution the parallel history of its Central Library is summarized. It is stressed that despite of unfavourable economical and political condition in Czech Republic for most of this time range the Central Library was able to maintain relative high standard not only as classical library but also to keep pace with development of electronic forms of scientific information. Thanks to this after opening of physical and financial borders Central Library was able systematically build up collection of digital information resources, both the secondary chemistry databases like CA, Beilstein or Gmelin but also very large collection of primary journals including so called archive collection covering full runs of most chemistry titles.

Nemethova A.,Ustav organicke Technology | Syslova K.,Ustav organicke Technology | Pelclova D.,University Karlova | Kacer P.,Ustav organicke Technology
Chemicke Listy | Year: 2012

The work deals with preparation and characterization of polymer immunoparticles used as a separation tool for biomarkers from biological fluids like urine, plasma etc. Polymer imunoparticles consist of antibodies immobilized in a polyvinyl alcohol and polyethylene glycol matrix. Prepared immunoparticles, containing monoclonal antibodies against 8-iso Prostaglandin F 2α, were used as a tool for a preliminary separation of 8-iso Prostaglandin F 2α (a marker of oxidative stress) from complex biological matrix (urine) before a highly specific and precise detection and quantification by LC-ESI-MS method. The developed method was characterized by high precision and accuracy. Functionality of the method was tested in a clinical study where urine concentration levels of 8-iso Prostaglandin F 2α in patients with diagnosis of asbestosis or silicosis (oxidative stress induced diseases) and control group were compared.

Vaclavika J.,Ustav organicke Technology | Pechacek J.,Ustav organicke Technology | Precha J.,Ustav organicke Technology | Kuzmab M.,Laborator charakterizace molekularni struktury | And 2 more authors.
Chemicke Listy | Year: 2012

Three methods for determination of enantioselectivity of asymmetric transfer hydrogenation of imines are presented: direct NMR observation of diastereomeric reduction products of a chiral imine, chiral solvation with Pirkle's alcohol, (-)-(1R)-1-(9-anthryl)-2,2,2-trifluoroethan-1-ol and precolumn derivatization with (-)-(1R)-menthyl chloroformate followed by GC analysis on a non-chiral column of the resulting diastereomeric carbamates.

Krejzova E.,Ustav organicke Technology | Belohlav Z.,Ustav organicke Technology
Chemicke Listy | Year: 2014

Orally dispersible tablets (ODT) are important for their fast disintegration in mouth as well as for their fast action and high biological availability of the drug. This dosage form is suitable in cases when the tablet swallowing is difficult, either for children or patients with dysphagia or for those who have no access to water. Development of ODT is complicated mainly by masking the unpleasant taste of the drug. It is necessary to keep the critical parameters of the tablets such as their hardness and fast disintegration. There are many methods of taste masking, but their application is very individual. In some cases the taste correction by with sweeteners and flavors can be sufficient, sometimes it is necessary to choose more sophisticated methods such as tablet coating or chemical modification of the active substance. In recent years, the taste masking using cyclodextrins and ion exchangers has been widely used. However, their use is limited to active substances capable of forming stable complexes with the tastemasking agents. The agents can negatively affect the dissolution profile of the active substance as well as slow down tablet disintegration. In a number of ODT efficient taste masking is achieved by a combination of appropriate physicochemical methods and technologies.

The posibility of comparing textual description of a problem is a clear advantage of the SciFinder resulting from abundant indexing of the paper content done by specialists in contrast to the description based on the paper title and abstract only. Search for individual compounds affords comparable results for both databases because both use the same principles of excerpting all compounds studied in a given document. In reaction search the advantage of Reaxys is distinct, much like the former databases Beilstein and Gmelin, which are built as reaction databases. The reaction module CASREACT in SciFinder is comparable with the Reaxys in the last 30-40 years only but offers no data for inorganic reactions. The patent search in Chemical Abstracts (CA) with traditional indepth coverage of patents and in the Reaxys are strong in looking for data of both organic and inorganic compounds. Despite the attempts of both databases at extending coverage and being competitive, the concept based on bibliographic records in CA and compound listing in Beilstein or Gmelin lead to different results, which is advantageous for completeness and relevance of the results.

Zamostny P.,Ustav organicke Technology | Kurc L.,Ustav organicke Technology
Chemicke Listy | Year: 2011

The quality and quantity of products obtained from wood by pyrolysis is governed by the process parameters, wood mass composition and wood properties. Liquid pyrolysis products are most preferred at present and thus fast pyrolysis becomes the technology of choice aiming at fast separation of reaction products from the reaction zone in order to prevent secondary reactions. Most frequently, fluid-bed or ablation reactors are employed to fulfil the task. The reactor design reflects the requirement as well as the rapid heat transfer to and within wood particles. The contents of three main wood components - hemicellulose, cellulose, and lignin - determine the optimal temperature for the process, since hemicellulose decomposes at 200- 260 °C, cellulose at 240-350 °C, and lignin at 250-500 ° C. Minor components of pyrolyzed wood feedstock can show significant catalytic or inhibiting effects. Therefore, the effects of minor components present in wood, added to or removed from, were studied extensively. Some metals, such as Al, Cr, Fe, Mn and Zn increase bio-oil yields, while alkaline earth metals decrease them. Therefore, addition of a salt, ion exchange or leaching can be used to alter product yields and composition. Other compounds that are reported to affect yields of bio-oil include phosphates or acid catalysts.

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