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Alexander Apelblat - One of the best experts on this subject based on the ideXlab platform.
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electrical conductances of dilute aqueous solutions of β lactam antibiotics of the penicillin group in the 278 15 k to 313 15 k temperature range sodium salts of oxacillin cloxacillin dicloxacillin and nafcillin
Journal of Molecular Liquids, 2015Co-Authors: Alexander Apelblat, Marija BesterrogacAbstract:Abstract Systematic determinations of electrical conductivities of sodium salts of semisynthetic penicillins, oxacillin, cloxacillin, dicloxacillin and nafcillin in the 278.15 K to 313.15 K temperature range are reported. These conductivities are examined by applying the Quint–Viallard conductivity equations and the Debye–Huckel equations for activity coefficients. Determined dissociation constants and the limiting conductances of involved anions are evaluated basing on the assumption that in dilute aqueous solutions these salts, similarly as sodium salts of natural penicillins, behave as acidic salts of dibasic acids which are the final products of Degradation Reactions in acidic media.
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electrical conductances of dilute aqueous solutions of sodium penicillin g potassium penicillin g and potassium penicillin v in the 278 15 313 15 k temperature range
Journal of Physical Chemistry B, 2007Co-Authors: Marija Besterrogac, Matjaz Boncina, Yoram Apelblat, Alexander ApelblatAbstract:Systematic determinations of electrical conductivities of sodium penicillin G, potassium penicillin G, and potassium penicillin V in the 278.15−313.15 K temperature range are reported. These conductivities are examined by applying the Quint−Viallard conductivity equations and the Debye−Huckel equations for activity coefficients. Determined dissociation constants and the limiting conductances of penicillin anions are based on the assumption that in dilute aqueous solutions, penicillin salts behave as acidic salts of dibasic acids, which are the final products of Degradation Reactions in acidic media.
Marija Besterrogac - One of the best experts on this subject based on the ideXlab platform.
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electrical conductances of dilute aqueous solutions of β lactam antibiotics of the penicillin group in the 278 15 k to 313 15 k temperature range sodium salts of oxacillin cloxacillin dicloxacillin and nafcillin
Journal of Molecular Liquids, 2015Co-Authors: Alexander Apelblat, Marija BesterrogacAbstract:Abstract Systematic determinations of electrical conductivities of sodium salts of semisynthetic penicillins, oxacillin, cloxacillin, dicloxacillin and nafcillin in the 278.15 K to 313.15 K temperature range are reported. These conductivities are examined by applying the Quint–Viallard conductivity equations and the Debye–Huckel equations for activity coefficients. Determined dissociation constants and the limiting conductances of involved anions are evaluated basing on the assumption that in dilute aqueous solutions these salts, similarly as sodium salts of natural penicillins, behave as acidic salts of dibasic acids which are the final products of Degradation Reactions in acidic media.
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electrical conductances of dilute aqueous solutions of sodium penicillin g potassium penicillin g and potassium penicillin v in the 278 15 313 15 k temperature range
Journal of Physical Chemistry B, 2007Co-Authors: Marija Besterrogac, Matjaz Boncina, Yoram Apelblat, Alexander ApelblatAbstract:Systematic determinations of electrical conductivities of sodium penicillin G, potassium penicillin G, and potassium penicillin V in the 278.15−313.15 K temperature range are reported. These conductivities are examined by applying the Quint−Viallard conductivity equations and the Debye−Huckel equations for activity coefficients. Determined dissociation constants and the limiting conductances of penicillin anions are based on the assumption that in dilute aqueous solutions, penicillin salts behave as acidic salts of dibasic acids, which are the final products of Degradation Reactions in acidic media.
Schlee Philipp - One of the best experts on this subject based on the ideXlab platform.
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Hardwood versus softwood Kraft lignin-precursor-product relationships in the manufacture of porous carbon nanofibers for supercapacitors
'Royal Society of Chemistry (RSC)', 2020Co-Authors: Schlee Philipp, Hosseinaei Omid, O'keefe, Christopher A., Mostazo-lópez, María José, Cazorla-amorós Diego, Herou Servann, Tomani Per, Grey, Clare P., Titirici, Maria MagdalenaAbstract:The process of stabilization is essential in the production of carbon fibers from lignins. During stabilization, the initially thermoplastic lignin polymer is converted to a thermoset polymer allowing for high-temperature treatment without a change in shape. In this work, hardwood (HKL) and softwood (SKL) Kraft lignins were stabilized in air at temperatures between 190 and 340 °C before carbonization at 800 °C in a nitrogen atmosphere. Due to the differences in side-chain linkages, functional groups and molar mass, the lignins exhibit different structural changes upon stabilization and hence develop different porosities upon carbonization. Both lignins undergo major crosslinking Reactions in the side chains at low temperatures and Degradation Reactions at high temperatures during stabilization. Crosslinking gives rise to narrow pore size distributions with mainly (sub-) nanometer pores, whereas Degradation Reactions lead to a more open pore structure with additional mesoporosity (>2 nm). When both types of Reactions take place simultaneously, highly accessible (sub-) nanoporosity can be effectively created, which boosts the performance of supercapacitors operating in 6 M KOH(aq). This effect terminates when the crosslinking Reactions cease and mainly Degradation Reactions take place, which occurs in HKL at 340 °C. SKL shows both a lower degree of crosslinking and Degradation and hence develops less specific surface area. The optimum performance in an aqueous alkaline supercapacitor is achieved with HKL stabilized at 310 °C. It shows a specific gravimetric capacitance of 164 F g-1 at 0.1 A g-1 and 119 F g-1 at 250 A g-1 with a capacitance retention of more than 90% after 10 000 cycles. This journal isPeer reviewe
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Hardwood versus softwood Kraft lignin – precursor-product relationships in the manufacture of porous carbon nanofibers for supercapacitors
'Royal Society of Chemistry (RSC)', 2020Co-Authors: Schlee Philipp, Hosseinaei Omid, Mostazo-lópez, María José, Cazorla-amorós Diego, Herou Servann, Tomani Per, Grey, Clare P., O'keeffe, Christopher A., Titirici Maria-magdalenaAbstract:The process of stabilization is essential in the production of carbon fibers from lignins. During stabilization, the initially thermoplastic lignin polymer is converted to a thermoset polymer allowing for high-temperature treatment without a change in shape. In this work, hardwood (HKL) and softwood (SKL) Kraft lignins were stabilized in air at temperatures between 190 and 340 °C before carbonization at 800 °C in a nitrogen atmosphere. Due to the differences in side-chain linkages, functional groups and molar mass, the lignins exhibit different structural changes upon stabilization and hence develop different porosities upon carbonization. Both lignins undergo major crosslinking Reactions in the side chains at low temperatures and Degradation Reactions at high temperatures during stabilization. Crosslinking gives rise to narrow pore size distributions with mainly (sub-) nanometer pores, whereas Degradation Reactions lead to a more open pore structure with additional mesoporosity (>2 nm). When both types of Reactions take place simultaneously, highly accessible (sub-) nanoporosity can be effectively created, which boosts the performance of supercapacitors operating in 6 M KOH(aq). This effect terminates when the crosslinking Reactions cease and mainly Degradation Reactions take place, which occurs in HKL at 340 °C. SKL shows both a lower degree of crosslinking and Degradation and hence develops less specific surface area. The optimum performance in an aqueous alkaline supercapacitor is achieved with HKL stabilized at 310 °C. It shows a specific gravimetric capacitance of 164 F g−1 at 0.1 A g−1 and 119 F g−1 at 250 A g−1 with a capacitance retention of more than 90% after 10 000 cycles.M. J. M. L. and D. C. A. thank Spanish Ministry of Science, Innovation and Universities and FEDER (project RTI2018-095291-B-I00) for financial support. C. P. G. and C. O'K. thank Shell. MMT and PS thank RISE AB for co-funding Philipp Schlee's PhD position
Philipp Schlee - One of the best experts on this subject based on the ideXlab platform.
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hardwood versus softwood kraft lignin precursor product relationships in the manufacture of porous carbon nanofibers for supercapacitors
Journal of Materials Chemistry, 2020Co-Authors: Philipp Schlee, Omid Hosseinaei, Christopher A O Keefe, Maria Jose Mostazolopez, Diego Cazorlaamoros, Servann Herou, Per Tomani, Clare P Grey, Mariamagdalena TitiriciAbstract:The process of stabilization is essential in the production of carbon fibers from lignins. During stabilization, the initially thermoplastic lignin polymer is converted to a thermoset polymer allowing for high-temperature treatment without a change in shape. In this work, hardwood (HKL) and softwood (SKL) Kraft lignins were stabilized in air at temperatures between 190 and 340 °C before carbonization at 800 °C in a nitrogen atmosphere. Due to the differences in side-chain linkages, functional groups and molar mass, the lignins exhibit different structural changes upon stabilization and hence develop different porosities upon carbonization. Both lignins undergo major crosslinking Reactions in the side chains at low temperatures and Degradation Reactions at high temperatures during stabilization. Crosslinking gives rise to narrow pore size distributions with mainly (sub-) nanometer pores, whereas Degradation Reactions lead to a more open pore structure with additional mesoporosity (>2 nm). When both types of Reactions take place simultaneously, highly accessible (sub-) nanoporosity can be effectively created, which boosts the performance of supercapacitors operating in 6 M KOH(aq). This effect terminates when the crosslinking Reactions cease and mainly Degradation Reactions take place, which occurs in HKL at 340 °C. SKL shows both a lower degree of crosslinking and Degradation and hence develops less specific surface area. The optimum performance in an aqueous alkaline supercapacitor is achieved with HKL stabilized at 310 °C. It shows a specific gravimetric capacitance of 164 F g−1 at 0.1 A g−1 and 119 F g−1 at 250 A g−1 with a capacitance retention of more than 90% after 10 000 cycles.
F M Costa - One of the best experts on this subject based on the ideXlab platform.
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photoDegradation of diquat and paraquat in aqueous solutions by titanium dioxide evolution of Degradation Reactions and characterisation of intermediates
Chemosphere, 2004Co-Authors: Helena M Florencio, Elisabete Pires, Ana L Castro, M R Nunes, Carlos Borges, F M CostaAbstract:Abstract The titanium dioxide assisted photoDegradation of Diquat and Paraquat herbicides solutions has been the subject of the present investigation, considering its direct application in the treatment of contaminated waters and soils. To have a better understanding of the photoDegradation process, different types of TiO 2 , commercial and ‘home prepared’ Ti 1− x Fe x O 2 ( x =0% and 4%), were used as catalysts, using an UV light as radiation source. The Degradation Reactions were followed by UV spectroscopy and the intermediates and reaction products were characterised by electrospray ionisation mass spectrometry (ESIMS) combined with collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS). The present study shows that, for photocatalytic Degradation of Diquat and Paraquat solutions, a basic pH can be determinant, as well as the type of catalyst. The type of catalyst can also strongly influence the Degradation pattern of the herbicide. Regarding complete Degradation, we were able to show that Diquat is more persistent than Paraquat . During the photocatalytic processes, several intermediate and reaction products are sequentially formed, to which structures are proposed.