{"title":"Isobaric vapour–liquid equilibria of the ternary system toluene + p-xylene + 1,2-dichloroethane","authors":"H. Kirss, L. Kudryavtseva, M. Kuus, E. Siimer","doi":"10.3176/chem.2002.4.03","DOIUrl":"https://doi.org/10.3176/chem.2002.4.03","url":null,"abstract":"","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83350018","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}
V. Chekulayev, L. Chekulayeva, R. Jäälaid, I. Shevchuk
{"title":"Kinetic studies on the mechanism of haematoporphyrin derivative photobleaching","authors":"V. Chekulayev, L. Chekulayeva, R. Jäälaid, I. Shevchuk","doi":"10.3176/chem.2002.1.05","DOIUrl":"https://doi.org/10.3176/chem.2002.1.05","url":null,"abstract":"","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"140 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79982765","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}
The paper provides an overview of theoretical basis, efficiency, economics, laboratory and pilot plant testing, design and modelling of different advanced oxidation processes (combinations of ozone and hydrogen peroxide with UV radiation and catalysts).
{"title":"ADVANCED OXIDATION PROCESSES – CURRENT STATUS AND PROSPECTS","authors":"R. Munter","doi":"10.1002/CHIN.200141291","DOIUrl":"https://doi.org/10.1002/CHIN.200141291","url":null,"abstract":"The paper provides an overview of theoretical basis, efficiency, economics, laboratory and pilot plant testing, design and modelling of different advanced oxidation processes (combinations of ozone and hydrogen peroxide with UV radiation and catalysts).","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"764 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76925871","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}
Phosphorus-carbon diad tautomerism was studied in phosphonium compounds with such strong electron acceptor substituents as cyano-, nitro-, fluorosul phonyl-, and trifluoromethyl- sulphonyl groups using semiempirical, ab initio, and DFT methods. It was shown that in the gas phase all studied monosubstituted species are in the phosphoryl form and no enol forms should be detectable. In contrast, for doubly substituted compounds enol forms should be well detectable and in some cases even predominant. Comparison of different calculation methods indicated that ab initio (HF/6-31 + G*) and DFT (B3LYP/6-311 + G**) calculations give close results. Both applied semiempirical methods (PM3 and MNDO/d) seem to overestimate strongly the stability of the enol form. It was also found that the MNDO/d method gives unrealistic results for compounds containing both hypervalent phosphorus and sulphur.
{"title":"PHOSPHORUS–CARBON DIAD TAUTOMERISM IN PHOSPHONIUM COMPOUNDS. THEORETICAL STUDY","authors":"P. Burk, K. Tämm","doi":"10.3176/chem.2001.4.06","DOIUrl":"https://doi.org/10.3176/chem.2001.4.06","url":null,"abstract":"Phosphorus-carbon diad tautomerism was studied in phosphonium compounds with such strong electron acceptor substituents as cyano-, nitro-, fluorosul phonyl-, and trifluoromethyl- sulphonyl groups using semiempirical, ab initio, and DFT methods. It was shown that in the gas phase all studied monosubstituted species are in the phosphoryl form and no enol forms should be detectable. In contrast, for doubly substituted compounds enol forms should be well detectable and in some cases even predominant. Comparison of different calculation methods indicated that ab initio (HF/6-31 + G*) and DFT (B3LYP/6-311 + G**) calculations give close results. Both applied semiempirical methods (PM3 and MNDO/d) seem to overestimate strongly the stability of the enol form. It was also found that the MNDO/d method gives unrealistic results for compounds containing both hypervalent phosphorus and sulphur.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82763203","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}
The ionic content of polar ice sheet is useful in tracing the sources of impurities, which lead to the final composition of the atmosphere. Ion chromatography is a suitable tool for analysing the ionic content of polar ice, provided precautions are taken to avoid ice contamination during sampling and analyses. In the present study a method for handling and analysing ice core samples was developed. The knowledge obtained was then applied for the determination of major ions in Dome B (East Antarctica) ice core to analyse the potential of extracted information for understanding the past atmospheric changes.
{"title":"ION CHROMATOGRAPHIC DETERMINATION OF MAJOR ANIONS AND CATIONS IN ANTARCTIC ICE","authors":"J. Ivask, J. Pentchuk","doi":"10.3176/chem.2001.1.06","DOIUrl":"https://doi.org/10.3176/chem.2001.1.06","url":null,"abstract":"The ionic content of polar ice sheet is useful in tracing the sources of impurities, which lead to the final composition of the atmosphere. Ion chromatography is a suitable tool for analysing the ionic content of polar ice, provided precautions are taken to avoid ice contamination during sampling and analyses. In the present study a method for handling and analysing ice core samples was developed. The knowledge obtained was then applied for the determination of major ions in Dome B (East Antarctica) ice core to analyse the potential of extracted information for understanding the past atmospheric changes.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87174998","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}
Janek Peterson, Arkadi Ebber, Veiko Allikmaa, M. Lopp
Generations 0 through 5 of ethylenediamine core poly(amidoamine) dendrimers were synthesized. The half-generations of the dendrimeric compounds were purified on silica gel and/or Sephadex LH-20. Capillary zone electrophoresis was applied to characterize the homogeneity of the individual generations.
{"title":"SYNTHESIS AND CZE ANALYSIS OF PAMAM DENDRIMERS WITH AN ETHYLENEDIAMINE CORE","authors":"Janek Peterson, Arkadi Ebber, Veiko Allikmaa, M. Lopp","doi":"10.3176/chem.2001.3.05","DOIUrl":"https://doi.org/10.3176/chem.2001.3.05","url":null,"abstract":"Generations 0 through 5 of ethylenediamine core poly(amidoamine) dendrimers were synthesized. The half-generations of the dendrimeric compounds were purified on silica gel and/or Sephadex LH-20. Capillary zone electrophoresis was applied to characterize the homogeneity of the individual generations.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80512415","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}
The influence of various concentrations of 15 detergents at different temperatures on the fluidity of membranes was analysed by fluorescence anisotropy of inserted 1,6-diphenyl-1,3,5- hexatriene in rat cortical and Sf9 cell membranes. Comparison of the obtained data with the abilities of the detergents to solubilize muscarinic receptor subtypes indicated that not only the fluidity of the micelles formed but also the micelle formation process, the lipid/protein ratio, and presence of sterols have significant influence on the efficiency of the solubilization of mAChR. Digitonin seems to exploit efficiently all these factors by its biphasic modulatory effect on membrane fluidity during the receptor solubilization.
{"title":"CHANGES IN MEMBRANE FLUIDITY DURING THE MICELLE FORMATION DETERMINE THE EFFICIENCY OF THE SOLUBILIZATION OF MUSCARINIC RECEPTORS","authors":"S. Kopanchuk, A. Rinken","doi":"10.3176/chem.2001.4.05","DOIUrl":"https://doi.org/10.3176/chem.2001.4.05","url":null,"abstract":"The influence of various concentrations of 15 detergents at different temperatures on the fluidity of membranes was analysed by fluorescence anisotropy of inserted 1,6-diphenyl-1,3,5- hexatriene in rat cortical and Sf9 cell membranes. Comparison of the obtained data with the abilities of the detergents to solubilize muscarinic receptor subtypes indicated that not only the fluidity of the micelles formed but also the micelle formation process, the lipid/protein ratio, and presence of sterols have significant influence on the efficiency of the solubilization of mAChR. Digitonin seems to exploit efficiently all these factors by its biphasic modulatory effect on membrane fluidity during the receptor solubilization.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80673108","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}
Mineral composition of algal biomass from Fucus vesiculosus (the Baltic Sea, Estonia) is rich in light elements (Mg, K, Ca, Na) and halogens (Br, I). Arsenic content is also high (over 300 ppm); the content of other toxic elements (Hg, Sb, Se, etc.) is extremely low. Mineralization of the algal whole biomass does not depend on seasonal varieties. The content of α -L-guluronic acid residues, and therefore the viscosity of alginates from the Baltic F. vesiculosus, is relatively low. Viscosic properties depend significantly on the storing and processing conditions of biomass; the polymer chain of alginates from this brown alga species is especially sensitive to high isolation temperatures.
来自黑角藻(爱沙尼亚波罗的海)的藻类生物量矿物成分富含轻元素(Mg、K、Ca、Na)和卤素(Br、I)，砷含量也很高(超过300 ppm);其他有毒元素(汞、锑、硒等)含量极低。整个藻类生物量的矿化不依赖于季节变化。α - l -古鲁醛酸残基的含量相对较低，因此波罗的海褐藻酸盐的粘度相对较低。生物质的粘度特性很大程度上取决于其储存和加工条件;这种褐藻的藻酸盐聚合物链对高分离温度特别敏感。
{"title":"ALGAL BIOMASS FROM Fucus vesiculosus (Phaeophyta): INVESTIGATION OF THE MINERAL AND ALGINATE COMPONENTS","authors":"K. Truus, M. Vaher, I. Taure","doi":"10.3176/chem.2001.2.04","DOIUrl":"https://doi.org/10.3176/chem.2001.2.04","url":null,"abstract":"Mineral composition of algal biomass from Fucus vesiculosus (the Baltic Sea, Estonia) is rich in light elements (Mg, K, Ca, Na) and halogens (Br, I). Arsenic content is also high (over 300 ppm); the content of other toxic elements (Hg, Sb, Se, etc.) is extremely low. Mineralization of the algal whole biomass does not depend on seasonal varieties. The content of α -L-guluronic acid residues, and therefore the viscosity of alginates from the Baltic F. vesiculosus, is relatively low. Viscosic properties depend significantly on the storing and processing conditions of biomass; the polymer chain of alginates from this brown alga species is especially sensitive to high isolation temperatures.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80721271","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}
Microcalorimetric measurements of excess molar enthalpies are reported for o-xylene + hexan-2-one + nonane and o-xylene + hexan-2-one at 298.15 K. The results for the ternary system are compared with those calculated by a modified Redlich-Kister equation. The temperature effect on the excess enthalpy is discussed.
{"title":"EXCESS MOLAR ENTHALPIES OF THE TERNARY SYSTEM o-XYLENE + HEXAN-2-ONE + NONANE AT 298.15 K","authors":"H. Kirss, M. Kuus, E. Siimer, L. Kudryavtseva","doi":"10.3176/chem.2001.2.03","DOIUrl":"https://doi.org/10.3176/chem.2001.2.03","url":null,"abstract":"Microcalorimetric measurements of excess molar enthalpies are reported for o-xylene + hexan-2-one + nonane and o-xylene + hexan-2-one at 298.15 K. The results for the ternary system are compared with those calculated by a modified Redlich-Kister equation. The temperature effect on the excess enthalpy is discussed.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78312527","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}
The volatile constituents of Matricaria recutita L. cultivated in Estonia were isolated by SDE and studied by GC/FID and GC/MS. Thirty-seven components were identified. The main components were bisabolol oxide A (20-33%) and B (8-12%), bisabolon oxide A (7-14%), (E)-β-farnesene (4-13%), α -bisabolol (8-14%), chamazulene (5-7%), and en-yn-dicycloether (17-22%). The content of sesquiterpenoid compounds was high, amounting to 70% of the total oil. Variations in the essential oil composition of different chamomile samples and the yields of oil during distillation are also reported.
{"title":"VOLATILE CONSTITUENTS OF Matricaria recutita L. FROM ESTONIA","authors":"A. Orav, T. Kailas, K. Ivask","doi":"10.3176/chem.2001.1.05","DOIUrl":"https://doi.org/10.3176/chem.2001.1.05","url":null,"abstract":"The volatile constituents of Matricaria recutita L. cultivated in Estonia were isolated by SDE and studied by GC/FID and GC/MS. Thirty-seven components were identified. The main components were bisabolol oxide A (20-33%) and B (8-12%), bisabolon oxide A (7-14%), (E)-β-farnesene (4-13%), α -bisabolol (8-14%), chamazulene (5-7%), and en-yn-dicycloether (17-22%). The content of sesquiterpenoid compounds was high, amounting to 70% of the total oil. Variations in the essential oil composition of different chamomile samples and the yields of oil during distillation are also reported.","PeriodicalId":20551,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Chemistry","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74416916","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}
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