Number of found documents: 7283
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Effects of urbanization on the landscape of a Modern City in Ghana: A case study of sunyani
Boateng, K. A.; Mensah, Caleb; Agyei, Thomas; Švik, Marian
2018 - English
According to the fifth assessment report of the Intergovernmental Panel on Climate Change, changes in land use through urbanization and agriculture are the key anthropogenic effects of climate change. Thus, the preservation of natural environment of urban areas is essential for conserving water and soil, while still adjusting the microclimatic variables (temperature, precipitation, relative humidity, etc.) and stabilizing the natural ecological system from destruction. It has been observed that most parts of city's green vegetation have been lost due to housing developments and commercial activities. This study was carried out to assess the effect of the change in land use on a modern city like Sunyani, by observing the significant changes in vegetation cover from LANDSAT TM imagery over a 31-year period (1986-2017). From the study, there was significant decline of vegetation cover from 1986 to 1999, and no significant change from 1999 to 2017. There were also significant changes in the built-up areas from 1986 to 1999 and no significant change from 1999 to 2017. Adoption of sustainable and environmentally friendly technologies that maintain open green vegetation is recommended for future city planning. Keywords: Climate change; Green vegetation; landsat; Open green spaces; Urbanization Available at various institutes of the ASCR
Effects of urbanization on the landscape of a Modern City in Ghana: A case study of sunyani

According to the fifth assessment report of the Intergovernmental Panel on Climate Change, changes in land use through urbanization and agriculture are the key anthropogenic effects of climate change. ...

Boateng, K. A.; Mensah, Caleb; Agyei, Thomas; Švik, Marian
Ústav výzkumu globální změny , 2018

Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions
Mareček, Vladimír
2018 - English
An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible electrolyte solutions (ITIES). The interfacial potential was controlled by the\ndistribution of a common tetralkylammonium (TAA+) ion. Changes in the TAA+\nconcentration at the interface were monitored by measuring the open circuit potential (OCP).\nTransfer of hydrated chloride ions is accompanied by the transfer of TAA+, decreasing its\nconcentration on the aqueous side of the interface. This process involves the co-extraction of\nwater molecules with the hydrated chloride ions and the formation of water clusters in the\norganic solvent phase. The ability to monitor the process from the very beginning of interface\nformation allowed us to obtain important kinetic data. Keywords: Liquid/liquid interface; Water co-extraction dynamics; Emulsification Available on request at various institutes of the ASCR
Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions

An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible ...

Mareček, Vladimír
Ústav fyzikální chemie J. Heyrovského, 2018

Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC
Tvorynska, S.; Barek, J.; Josypčuk, Bohdan
2018 - English
In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam electrode, namely mercury meniscus modified, polished and compared with hanging mercury drop electrode using differential pulse voltammetry and direct current voltammetry. The effect of adsorption and the reduction mechanism on tested electrodes were described in detail. Measurements with amalgam electrodes showed good reproducibility, stability and high sensitivity. As a result, they were successfully applied for the determination of investigated azo dyes in different commercial drink samples. Keywords: voltammetry; azo dyes; amaranth Available at various institutes of the ASCR
Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC

In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam ...

Tvorynska, S.; Barek, J.; Josypčuk, Bohdan
Ústav fyzikální chemie J. Heyrovského, 2018

Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors
Koláčná, Lucie; Tobrman, T.; Ludvík, Jiří
2018 - English
A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core were electrochemically investigated in order to determine the influence of individual parts of the molecule on the redox properties, to describe the location of the reduction center and to understand the structure - redox activity relationship of the mentioned compounds. Keywords: pyrene; cyclobutene; polarography Available at various institutes of the ASCR
Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors

A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core ...

Koláčná, Lucie; Tobrman, T.; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2018

Proton Detection of Carbon-Carbon Couplings between Chemically Equivalent Nuclei.
Blechta, Vratislav; Sýkora, Jan
2018 - English
Keywords: carbon-carbon couplings; chemical equivalent nuclei Available in a digital repository NRGL
Proton Detection of Carbon-Carbon Couplings between Chemically Equivalent Nuclei.

Blechta, Vratislav; Sýkora, Jan
Ústav chemických procesů, 2018

Generování těkavých specií přechodných kovů pro analytickou atomovou spektrometrii se zaměřením na účinnost generování, prekoncentraci, identitu těkavých specií a studium mechanismu generování
Musil, Stanislav
2018 - Czech
Předkládaný soubor 8 publikovaných prací a jednoho patentu se věnuje právě této problematice. Zaměřili jsme se na studium mechanismu generování a identifikaci těkavých specií v plynné fázi při generovaní Ag1, Au3 a Cu9 s detekcí AAS. Pomocí přístrojů pro charakterizaci velikosti částic aerosolu a transmisní elektronové mikroskopie jsme identifikovali nanočástice těchto kovů v plynné fázi. Keywords: volatile species; atomic absorption spectrometry; generation of volatile species Available on request at various institutes of the ASCR
Generování těkavých specií přechodných kovů pro analytickou atomovou spektrometrii se zaměřením na účinnost generování, prekoncentraci, identitu těkavých specií a studium mechanismu generování

Předkládaný soubor 8 publikovaných prací a jednoho patentu se věnuje právě této problematice. Zaměřili jsme se na studium mechanismu generování a identifikaci těkavých specií v plynné fázi při ...

Musil, Stanislav
Ústav analytické chemie, 2018

Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
2018 - English
Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being developed. Wide variety of water-immiscible supported liquid membranes\n(SLMs) were tested. Highest enrichment factors were obtained using butyl benzoate as SLM.\nEnrichment factors for 30 min HF-LPME were 3. 0.74 for HVA and 5. 0.45 for VMA,\nrespectively. Repeatability of HF-LPME of microM HVA or VMA was 19.0% for HVA and\n7.9 % for VMA (n=5), respectively. Keywords: Hollow-fibres; Liquid phase microextraction; Voltammetry Available at various institutes of the ASCR
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers

Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being ...

Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2018

Electrochemical Study of the Supported Iron Oxide Catalysts
Gál, M.; Horváth, B.; Navrátil, Tomáš
2018 - English
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this short contribution we tried to characterize supported iron(III) oxide\ncatalyst with different amount of Fe and to find an optimal iron(III) oxide content for the best\ncatalysts performance. The importance of phase quality on the selectivity of respective\ncatalysts samples is also discussed. Linear sweep voltammetry was chosen for this purpose.\nResults obtained by electrochemical methods are compared with efficiency (selectivity) of\nrespective catalysts. Keywords: Catalyst; Linear sweep voltammetry; Propylene oxide Available on request at various institutes of the ASCR
Electrochemical Study of the Supported Iron Oxide Catalysts

Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this ...

Gál, M.; Horváth, B.; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2018

HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid
Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - English
Determination of 5-HIAA in human urine was succssfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique; presented method does not need any sample pre-treatment apart from SPE procedure, which replaced filtration of samples of human urine to avoid problems with clogging a HPLC column. The found native\nconcentrations of 5-HIAA in human urine using HPLC-ED with SPE fully corresponds with published normal concentrations in urine (17.8 - 58.3 micromol l-1). The found native concentrations of 5-HIAA were 18.4 micromol L-1 (calculated from peak height). The presented method is fast and could be used for simple\nscreening of human urine, because HPLC-ED/UV allows simultaneous determination of 5-HIAA, HVA, and VMA as important tumour biomarkers. Keywords: HPLC; electrochemical detection; spectrophotometric detection Available at various institutes of the ASCR
HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid

Determination of 5-HIAA in human urine was succssfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique; presented method does not need any sample pre-treatment apart from ...

Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2018

Introducing Functionality by Graphene Covalent Grafting
Kovaříček, Petr; Kalbáč, Martin
2018 - English
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent functionalization. We have exploited protocols for surface grafting by diazonium salts, by nucleophilic and electrophilic substitution to perform graphene covalent modification of graphene on substrates. The painstaking analysis problem of monolayered materials was addressed using Raman spectroscopy, SERS, SEIRA, MS, AFM, XPS and SEM/EDX. The covalent grafting was shown to tolerate the transfer process, thus allowing ex post transfer from copper to other substrates. Functional devices often require combination of several materials with specific functions, such as graphene-polymer hybrid heterostructures. We have used the developed methodology of chemical functionalization for preparation of PEDOT:Graphene bilayers by selective in situ polymerization of EDOT on covalently functionalized graphene. The polymerization proceeds exclusively on the grafted graphene, and patterned structures with high spatial resolution down to 3 μm could have been prepared. The composite exhibits enhanced efficiency of electrochemical doping compared to pristine graphene, unsymmetrical transport characteristic with very good hole-transporting properties and efficient electronic communication between the two materials. The covalent functionalization of graphene thus introduces advanced functionality to the material, broadening its scope of applications. Keywords: graphene; covalent functionalization; PEDOT Available at various institutes of the ASCR
Introducing Functionality by Graphene Covalent Grafting

Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent ...

Kovaříček, Petr; Kalbáč, Martin
Ústav fyzikální chemie J. Heyrovského, 2018

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