Abstract Dimethyl sulfoxide (DMSO) is an aprotic organic solvent widely used in laboratory practice due to its ability to dissolve both polar and nonpolar compounds. However, DMSO is also commonly known as a strongly coordinating solvent, especially towards transition metal containing complexes. In this study, estimation of the coordination ability of DMSO towards the Cu(II) ion was attempted, employing a model system composed of 3′,4′-dihydroxyflavone-Cu(II) complex in the presence of explicit DMSO molecules, using the density functional theory (DFT). Nature of the Cu-DMSO chemical interaction (i.e. Cu-O bonding) was studied within the framework of quantum theory of atoms in molecules (QTAIM). Impact of DMSO coordination on the charge and spin distribution at Cu(II) ion was inspected using Mulliken population and QTAIM analysis.
{"title":"Dimethyl sulfoxide as a strongly coordinating solvent: 3′,4′-dihydroxyflavone-Cu(II)-DMSO system case study","authors":"Miriama Šimunková, Michal Malček","doi":"10.2478/acs-2020-0022","DOIUrl":"https://doi.org/10.2478/acs-2020-0022","url":null,"abstract":"Abstract Dimethyl sulfoxide (DMSO) is an aprotic organic solvent widely used in laboratory practice due to its ability to dissolve both polar and nonpolar compounds. However, DMSO is also commonly known as a strongly coordinating solvent, especially towards transition metal containing complexes. In this study, estimation of the coordination ability of DMSO towards the Cu(II) ion was attempted, employing a model system composed of 3′,4′-dihydroxyflavone-Cu(II) complex in the presence of explicit DMSO molecules, using the density functional theory (DFT). Nature of the Cu-DMSO chemical interaction (i.e. Cu-O bonding) was studied within the framework of quantum theory of atoms in molecules (QTAIM). Impact of DMSO coordination on the charge and spin distribution at Cu(II) ion was inspected using Mulliken population and QTAIM analysis.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"38 - 48"},"PeriodicalIF":0.8,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69086405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nemanja Koljančić, O. Vyviurska, Milica Balaban, I. Špánik
Abstract Once they reach the environment, petroleum hydrocarbons undergo various chemical, physico-chemical and biochemical transformation processes. Organic compounds which are not or are very poorly subject to these processes are thermodynamically the most stable isomers and they are called biological markers (biomarkers). This paper presents the results of the determination of organic substances in twelve samples taken in the area of the city of Banja Luka (Bosnia and Herzegovina). Two soil samples were taken in the Banja Luka city heating plant area and ten river sediment and soil samples were taken in the upper and lower basin of the Vrbas river in the Banja Luka city area. The aim of this study was to determine the biomarkers of oil-type pollutants in contaminated samples as well as the type of organic substances in samples taken near the contaminated area. Assisted solvent extraction was used to isolate the total petroleum hydrocarbons (TPH) from all twelve samples. Fractionation of the extracts into saturated and aromatic hydrocarbon fractions was performed by column chromatography. The fractions were analyzed by gas chromatography-mass spectrometry (GC-MS). On basis of the obtained chromatograms, biomarkers of petroleum pollutants and specific correlation parameters of organic substances in the samples were determined. The dominance of n-alkanes with odd C atoms as well as the presence of an unresolved complex mixture (UCM) on chromatograms of saturated and aromatic hydrocarbons showed the presence of anthropogenic organic substances of petroleum origin in the analyzed samples. Based on the obtained chromatograms, it can be concluded that microbial degradation of hydrocarbons in all samples occurred.
{"title":"Determination of biological markers of organic substances in sediment and soil samples by gas chromatography","authors":"Nemanja Koljančić, O. Vyviurska, Milica Balaban, I. Špánik","doi":"10.2478/acs-2020-0006","DOIUrl":"https://doi.org/10.2478/acs-2020-0006","url":null,"abstract":"Abstract Once they reach the environment, petroleum hydrocarbons undergo various chemical, physico-chemical and biochemical transformation processes. Organic compounds which are not or are very poorly subject to these processes are thermodynamically the most stable isomers and they are called biological markers (biomarkers). This paper presents the results of the determination of organic substances in twelve samples taken in the area of the city of Banja Luka (Bosnia and Herzegovina). Two soil samples were taken in the Banja Luka city heating plant area and ten river sediment and soil samples were taken in the upper and lower basin of the Vrbas river in the Banja Luka city area. The aim of this study was to determine the biomarkers of oil-type pollutants in contaminated samples as well as the type of organic substances in samples taken near the contaminated area. Assisted solvent extraction was used to isolate the total petroleum hydrocarbons (TPH) from all twelve samples. Fractionation of the extracts into saturated and aromatic hydrocarbon fractions was performed by column chromatography. The fractions were analyzed by gas chromatography-mass spectrometry (GC-MS). On basis of the obtained chromatograms, biomarkers of petroleum pollutants and specific correlation parameters of organic substances in the samples were determined. The dominance of n-alkanes with odd C atoms as well as the presence of an unresolved complex mixture (UCM) on chromatograms of saturated and aromatic hydrocarbons showed the presence of anthropogenic organic substances of petroleum origin in the analyzed samples. Based on the obtained chromatograms, it can be concluded that microbial degradation of hydrocarbons in all samples occurred.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"34 - 40"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47282805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikolas Gróf, J. Barbušová, Kristína Hencelová, M. Hutňan
Abstract This study is focused on the effect of biogas recirculation with hydrogen sulfide removal on anaerobic treatment of sulfur-enriched synthetic wastewater in a UASB reactor. The presence of hydrogen sulfide in biogas causes problems in its further energy recovery while sulfides inhibit the anaerobic process. The reactor was gradually loaded with sulfates and their effect on the reactor operation was monitored. At the same time, external absorption of hydrogen sulfide from biogas with absorbent regeneration was operated. The results show that low concentrations of added sulfates support biogas production. At the sulfate concentration of 125 mg l−1, biogas production increased by approximately 2 l d−1. However, further increasing of the amount of sulfates in the substrate led to the opposite effect. At twice the amount of sulfates, the biogas production decrease by 1 l d−1 and its adverse effects on the removal of N-NH4, NC and P-PO4 were observed. Biogas recirculation through the absorption column ensured a decrease in the hydrogen sulfide concentration from 19 960 ppm to 4 030 ppm and an increase in the methane content from 59.2 % to 83 % and also a decrease in the sulfides concentration in the reactor. From the measured data it can be concluded that this method reduces sulfides inhibition.
摘要本研究的重点是在UASB反应器中，沼气再循环和硫化氢去除对含硫合成废水厌氧处理的影响。沼气中硫化氢的存在会导致其进一步的能量回收出现问题，而硫化物会抑制厌氧过程。反应器逐渐装载硫酸盐，并监测它们对反应器操作的影响。同时，采用吸收剂再生法对外吸收沼气中的硫化氢进行了操作。结果表明，低浓度的添加硫酸盐支持沼气生产。硫酸盐浓度为125 mg l−1时，沼气产量增加了约2 l d−1。然而，底物中硫酸盐含量的进一步增加导致了相反的效果。在硫酸盐用量为两倍的情况下，沼气产量下降了1 l d−1，并观察到其对去除N-NH4、NC和P-PO4的不利影响。通过吸收柱的生物气体再循环确保了硫化氢浓度从19 960 ppm降低到4 030 ppm，甲烷含量从59.2%增加到83%，以及反应器中硫化物浓度的降低。从测量数据可以得出结论，该方法降低了硫化物的抑制作用。
{"title":"Absorption removal of hydrogen sulfide from recirculated biogas","authors":"Nikolas Gróf, J. Barbušová, Kristína Hencelová, M. Hutňan","doi":"10.2478/acs-2020-0003","DOIUrl":"https://doi.org/10.2478/acs-2020-0003","url":null,"abstract":"Abstract This study is focused on the effect of biogas recirculation with hydrogen sulfide removal on anaerobic treatment of sulfur-enriched synthetic wastewater in a UASB reactor. The presence of hydrogen sulfide in biogas causes problems in its further energy recovery while sulfides inhibit the anaerobic process. The reactor was gradually loaded with sulfates and their effect on the reactor operation was monitored. At the same time, external absorption of hydrogen sulfide from biogas with absorbent regeneration was operated. The results show that low concentrations of added sulfates support biogas production. At the sulfate concentration of 125 mg l−1, biogas production increased by approximately 2 l d−1. However, further increasing of the amount of sulfates in the substrate led to the opposite effect. At twice the amount of sulfates, the biogas production decrease by 1 l d−1 and its adverse effects on the removal of N-NH4, NC and P-PO4 were observed. Biogas recirculation through the absorption column ensured a decrease in the hydrogen sulfide concentration from 19 960 ppm to 4 030 ppm and an increase in the methane content from 59.2 % to 83 % and also a decrease in the sulfides concentration in the reactor. From the measured data it can be concluded that this method reduces sulfides inhibition.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"13 - 18"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45343649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrea Štefunková, Klára Cverenkárová, Monika Krahulcová, T. Mackuľak, L. Bírošová
Abstract This work deals with the occurrence of selected antibiotic resistant bacteria in Slovak surface waters. Total and antibiotic resistant coliform bacteria, enterococci and coagulase positive staphylococci were determined in 34 samples of surface water from rivers and still waters (dams, natural lakes, thermal bath) some of them used for recreational swimming. Sampling was performed during summer season 2017 (July and August). The number of total coliforms ranged from 1.74 log CFU/10 mL to 3.69 log CFU/10 mL. Coliform bacteria were registered in each tested sample. The highest number was observed in the sample from river Hron. Majority of samples contained ampicillin and tetracycline resistant bacteria. Enterococci were determined in 70 % of samples ranging from 0.78 log CFU/10 mL to 3.81 log CFU/10 mL. The highest number of enterococci was observed in river Váh. Ampicillin and vancomycin resistance prevailed over ciprofloxacin and gentamicin resistance. Coagulase positive staphylococci were present in 91 % of samples in the range of 0.70—3.03 log CFU/10 mL. Antibiotic resistant coagulase positive staphylococci were observed only in 32 % of samples, predominantly from rivers. In these samples, chloramphenicol resistance predominated. In three samples of water used for recreational purposes, the limit value for enterococci and E. coli according to Slovak legislation (Decree no. 308/2012 Coll.) for the quality of water in natural swimming pools during bathing season was exceeded.
{"title":"Antibiotic resistant bacteria in surface waters in Slovakia","authors":"Andrea Štefunková, Klára Cverenkárová, Monika Krahulcová, T. Mackuľak, L. Bírošová","doi":"10.2478/acs-2020-0010","DOIUrl":"https://doi.org/10.2478/acs-2020-0010","url":null,"abstract":"Abstract This work deals with the occurrence of selected antibiotic resistant bacteria in Slovak surface waters. Total and antibiotic resistant coliform bacteria, enterococci and coagulase positive staphylococci were determined in 34 samples of surface water from rivers and still waters (dams, natural lakes, thermal bath) some of them used for recreational swimming. Sampling was performed during summer season 2017 (July and August). The number of total coliforms ranged from 1.74 log CFU/10 mL to 3.69 log CFU/10 mL. Coliform bacteria were registered in each tested sample. The highest number was observed in the sample from river Hron. Majority of samples contained ampicillin and tetracycline resistant bacteria. Enterococci were determined in 70 % of samples ranging from 0.78 log CFU/10 mL to 3.81 log CFU/10 mL. The highest number of enterococci was observed in river Váh. Ampicillin and vancomycin resistance prevailed over ciprofloxacin and gentamicin resistance. Coagulase positive staphylococci were present in 91 % of samples in the range of 0.70—3.03 log CFU/10 mL. Antibiotic resistant coagulase positive staphylococci were observed only in 32 % of samples, predominantly from rivers. In these samples, chloramphenicol resistance predominated. In three samples of water used for recreational purposes, the limit value for enterococci and E. coli according to Slovak legislation (Decree no. 308/2012 Coll.) for the quality of water in natural swimming pools during bathing season was exceeded.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"464 1","pages":"63 - 71"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41282352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Kubasová, S. Zichová, Adriána Brisudová, S. Hrouzková
Abstract Single drop microextraction has become a widespread liquid/liquid microextraction technique owing to its simplicity, high preconcentration factor and low consumption of organic solvents in the extraction due to direct introduction of the very low volume of extract into the analytical system. Crucial features ensuring excellent repeatability of single drop microextraction include: solvent volume, solvent type, sample agitation, salts addition, and pH. The influence of sample quality on the microdrop volume and agitation type was studied. Effect of the sample matrix, such as water, acid content samples (orange juice), sample containing alcohol (plum brandy) and protein content sample (milk), on the microdrop hold-up was also investigated. For water analysis, several organic solvents such as chloroform, dichloromethane, tetrachloromethane, tetrachloroethane and chlorobenzene were tested; last three mentioned were suitable for SDME experiments. For milk samples analysis, chlorobenzene microdrop was found to be optimal; advantage of salt addition has been reported. For orange samples, 1:10 dilution was suggested with stable microdrop volumes (toluene) of up to 6 µL for lower stirring rates (100 rpm and 250 rpm). For alcohol-content samples, the change of alcohol percentage of real-life samples had to be considered. A strong influence of the matrix quality on the microdrop stability has been proven.
{"title":"Sample matrix influence on microdrop hold-up in single drop microextraction","authors":"N. Kubasová, S. Zichová, Adriána Brisudová, S. Hrouzková","doi":"10.2478/acs-2020-0004","DOIUrl":"https://doi.org/10.2478/acs-2020-0004","url":null,"abstract":"Abstract Single drop microextraction has become a widespread liquid/liquid microextraction technique owing to its simplicity, high preconcentration factor and low consumption of organic solvents in the extraction due to direct introduction of the very low volume of extract into the analytical system. Crucial features ensuring excellent repeatability of single drop microextraction include: solvent volume, solvent type, sample agitation, salts addition, and pH. The influence of sample quality on the microdrop volume and agitation type was studied. Effect of the sample matrix, such as water, acid content samples (orange juice), sample containing alcohol (plum brandy) and protein content sample (milk), on the microdrop hold-up was also investigated. For water analysis, several organic solvents such as chloroform, dichloromethane, tetrachloromethane, tetrachloroethane and chlorobenzene were tested; last three mentioned were suitable for SDME experiments. For milk samples analysis, chlorobenzene microdrop was found to be optimal; advantage of salt addition has been reported. For orange samples, 1:10 dilution was suggested with stable microdrop volumes (toluene) of up to 6 µL for lower stirring rates (100 rpm and 250 rpm). For alcohol-content samples, the change of alcohol percentage of real-life samples had to be considered. A strong influence of the matrix quality on the microdrop stability has been proven.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"19 - 25"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42194001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Patrik Macúrik, R. Anyszka, I. Hudeč, Terézia Malčeková, J. Kruželák
Abstract The study was focused on the investigation of trans-polyoctylene (TOR) influence on cross-linking as well as mechanical and rheological properties of rubber compounds based on styrene-butadiene rubber (SBR). SBR was compounded with different proportions of TOR in the concentration range from 0 to 30 phr. Integration of TOR into rubber leads to the prolongation of the optimum curing time and scorch time and thus the decrease of the curing rate. Higher content of TOR led to less viscous rubber due to the plasticizing effect. Cross-link density of vulcanizates was reduced, which correlates with higher elongation at break. Tensile strength and hardness of vulcanizates increased with the increasing TOR content, probably due to the increasing amount of the crystalline phase.
{"title":"Influence of trans-polyoctylene rubber content on styrene-butadiene rubber properties","authors":"Patrik Macúrik, R. Anyszka, I. Hudeč, Terézia Malčeková, J. Kruželák","doi":"10.2478/acs-2020-0001","DOIUrl":"https://doi.org/10.2478/acs-2020-0001","url":null,"abstract":"Abstract The study was focused on the investigation of trans-polyoctylene (TOR) influence on cross-linking as well as mechanical and rheological properties of rubber compounds based on styrene-butadiene rubber (SBR). SBR was compounded with different proportions of TOR in the concentration range from 0 to 30 phr. Integration of TOR into rubber leads to the prolongation of the optimum curing time and scorch time and thus the decrease of the curing rate. Higher content of TOR led to less viscous rubber due to the plasticizing effect. Cross-link density of vulcanizates was reduced, which correlates with higher elongation at break. Tensile strength and hardness of vulcanizates increased with the increasing TOR content, probably due to the increasing amount of the crystalline phase.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"1 - 5"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46313799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lucia Hoppanová, V. Medvecká, Juliana Dylíková, D. Hudecová, B. Kaliňáková, S. Kryštofová, A. Zahoranová
Abstract In order to reduce the environmental burden of chemicals, various new alternatives to seed protection are being sought. Our aim was to find an environmentally acceptable solution leading to the inactivation of seed-borne phytopathogenic fungi Fusarium culmorum on the surface of wheat and barley seeds with a positive effect on their germination. As a low-temperature plasma (LTP) source, a Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used. Plasma generated by DCSBD is non-equilibrium, cold, diffuse, macroscopically homogeneous even in ambient air at atmospheric pressure. Experimental results showed that LTP treatment in the range of 120—300 s significantly inhibits the growth of F. culmorum on the surface of the seeds. The efficiency of LTP treatment was compared with traditional seed protection processes using chemical fungicide and also with combined seed pretreatment by plasma and subsequent application of chemical fungicide. No growth of F. culmorum was observed after the combination of Vitavax 2000 fungicide application in the dose of 10 % and 60 s of LTP treatment even on the 5th day of incubation. Better wettability of seeds with the chemical fungicide was related to the change on seed surface, which becomes hydrophilic after 10 s of LTP application. Short LTP exposure times did not affect germination and improved the growth parameter of cereal seeds. By combining physical (LTP) and chemical (Vitavax 2000) treatments of cereal seeds, it is possible to effectively reduce the required amount of chemical fungicide and to stimulate germination and early growth seed parameters.
{"title":"Low-temperature plasma applications in chemical fungicide treatment reduction","authors":"Lucia Hoppanová, V. Medvecká, Juliana Dylíková, D. Hudecová, B. Kaliňáková, S. Kryštofová, A. Zahoranová","doi":"10.2478/acs-2020-0005","DOIUrl":"https://doi.org/10.2478/acs-2020-0005","url":null,"abstract":"Abstract In order to reduce the environmental burden of chemicals, various new alternatives to seed protection are being sought. Our aim was to find an environmentally acceptable solution leading to the inactivation of seed-borne phytopathogenic fungi Fusarium culmorum on the surface of wheat and barley seeds with a positive effect on their germination. As a low-temperature plasma (LTP) source, a Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used. Plasma generated by DCSBD is non-equilibrium, cold, diffuse, macroscopically homogeneous even in ambient air at atmospheric pressure. Experimental results showed that LTP treatment in the range of 120—300 s significantly inhibits the growth of F. culmorum on the surface of the seeds. The efficiency of LTP treatment was compared with traditional seed protection processes using chemical fungicide and also with combined seed pretreatment by plasma and subsequent application of chemical fungicide. No growth of F. culmorum was observed after the combination of Vitavax 2000 fungicide application in the dose of 10 % and 60 s of LTP treatment even on the 5th day of incubation. Better wettability of seeds with the chemical fungicide was related to the change on seed surface, which becomes hydrophilic after 10 s of LTP application. Short LTP exposure times did not affect germination and improved the growth parameter of cereal seeds. By combining physical (LTP) and chemical (Vitavax 2000) treatments of cereal seeds, it is possible to effectively reduce the required amount of chemical fungicide and to stimulate germination and early growth seed parameters.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"26 - 33"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45223703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The paper reveals three applications of neural network predictive control (NNPC) to a system of four heat exchangers (HEs) in series with counterflow configuration to save energy expressed by cooling water in the system of HEs cooling the distillation product. Neural networks (NNs) are used at first in conventional NNPC and subsequently, neural network predictive controllers (NNPCLs) are employed as a master controller in a cascade control, and as a feedback controller in the control system with disturbance measurement. Neural-network-predictive-control-based (NNPC-based) feedback control systems are compared with PI controller based feedback control loop. Series of simulation experiments were done and the results showed that using NNPC-based cascade control reduced cooling water consumption. This control system also significantly reduced the settling time and overshoots in the control responses and provided the best assessed integral quality criteria compared to other control systems. NNPC-based cascade control can also be interesting for industrial use. Generally, simulation results proved that NNPC-based control systems are promising means for the improvement of HEs control and achievement of energy saving.
{"title":"Control of heat exchangers in series using neural network predictive controllers","authors":"A. Vasickaninova, M. Bakosová, A. Mészáros","doi":"10.2478/acs-2020-0007","DOIUrl":"https://doi.org/10.2478/acs-2020-0007","url":null,"abstract":"Abstract The paper reveals three applications of neural network predictive control (NNPC) to a system of four heat exchangers (HEs) in series with counterflow configuration to save energy expressed by cooling water in the system of HEs cooling the distillation product. Neural networks (NNs) are used at first in conventional NNPC and subsequently, neural network predictive controllers (NNPCLs) are employed as a master controller in a cascade control, and as a feedback controller in the control system with disturbance measurement. Neural-network-predictive-control-based (NNPC-based) feedback control systems are compared with PI controller based feedback control loop. Series of simulation experiments were done and the results showed that using NNPC-based cascade control reduced cooling water consumption. This control system also significantly reduced the settling time and overshoots in the control responses and provided the best assessed integral quality criteria compared to other control systems. NNPC-based cascade control can also be interesting for industrial use. Generally, simulation results proved that NNPC-based control systems are promising means for the improvement of HEs control and achievement of energy saving.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"41 - 48"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47314952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Klaudia Karkeszová, V. Illeová, P. Kis, V. Mastihuba, M. Polakovič
Abstract β-Apiosidase is a rare glycosidase applied in winemaking for flavour enhancement. This enzyme is involved in the release of volatile terpenes by hydrolysis of their odourless glycosidic precursors. It is found as a minor component in commercial pectinase/cellulase preparations. Microbial production of β-apiosidase by two Aspergillus sp. strains was investigated. Apiin-induced production of this extracellular glycosidase was confirmed only during the cultivation of Aspergillus niger CBS 554.65 but the high productivity value reported in the work of Dupin et al. (1992) J. Agric. Food Chem. 40(10): 1886—1891 could not be reproduced. The achieved productivity was by far not satisfactory considering the apiin cost. Commercial enzyme preparations with β-apiosidase side-activity thus remain a better alternative as the enzyme source for biocatalytic applications.
{"title":"Apiin-induction of β-apiosidase production by Aspergillus sp. strains","authors":"Klaudia Karkeszová, V. Illeová, P. Kis, V. Mastihuba, M. Polakovič","doi":"10.2478/acs-2020-0011","DOIUrl":"https://doi.org/10.2478/acs-2020-0011","url":null,"abstract":"Abstract β-Apiosidase is a rare glycosidase applied in winemaking for flavour enhancement. This enzyme is involved in the release of volatile terpenes by hydrolysis of their odourless glycosidic precursors. It is found as a minor component in commercial pectinase/cellulase preparations. Microbial production of β-apiosidase by two Aspergillus sp. strains was investigated. Apiin-induced production of this extracellular glycosidase was confirmed only during the cultivation of Aspergillus niger CBS 554.65 but the high productivity value reported in the work of Dupin et al. (1992) J. Agric. Food Chem. 40(10): 1886—1891 could not be reproduced. The achieved productivity was by far not satisfactory considering the apiin cost. Commercial enzyme preparations with β-apiosidase side-activity thus remain a better alternative as the enzyme source for biocatalytic applications.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"72 - 76"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49439680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Since environmental pollution is increasing, scientists try to find a sustainable way for its clean up and for environment protection. Due to increasing knowledge of genetics and recombinant technologies, recombinant enzymes have been increasingly applied for these purposes. This article deals with the possibilities of environmental treatment with different types of enzymes produced by P. pastoris. Environment is polluted mostly with pesticides, wastewaters, phenol compounds, plastics, toxic compounds, wastes from medical treatment, etc. All these compounds have to be eliminated considering the deteriorating biodiversity, human health, and condition of plants. Enzymes are an environmentally friendly way of such treatment.
{"title":"Pichia pastoris — recombinant enzyme producent for environment treatment — review","authors":"Tamara Kyzeková, Vladimír Krasňan, M. Rebroš","doi":"10.2478/acs-2020-0016","DOIUrl":"https://doi.org/10.2478/acs-2020-0016","url":null,"abstract":"Abstract Since environmental pollution is increasing, scientists try to find a sustainable way for its clean up and for environment protection. Due to increasing knowledge of genetics and recombinant technologies, recombinant enzymes have been increasingly applied for these purposes. This article deals with the possibilities of environmental treatment with different types of enzymes produced by P. pastoris. Environment is polluted mostly with pesticides, wastewaters, phenol compounds, plastics, toxic compounds, wastes from medical treatment, etc. All these compounds have to be eliminated considering the deteriorating biodiversity, human health, and condition of plants. Enzymes are an environmentally friendly way of such treatment.","PeriodicalId":7088,"journal":{"name":"Acta Chimica Slovaca","volume":"13 1","pages":"108 - 118"},"PeriodicalIF":0.8,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46779586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：