The nitrate complexes of cerium, praseodymium and neodymium with 1,10-phenanthroline （phen） of general formula [Ln（phen）2（NO3）2（H2O）2]·NO3 （where, Ln=Ce, Pr and Nd） were prepared and characterized by X-...The nitrate complexes of cerium, praseodymium and neodymium with 1,10-phenanthroline （phen） of general formula [Ln（phen）2（NO3）2（H2O）2]·NO3 （where, Ln=Ce, Pr and Nd） were prepared and characterized by X-ray crystallography. Thermolysis of these complexes was investigated by simultaneous thermogravimetry （TG） and differential thermal analysis （DTA）. Isothermal TG was taken to evaluate the kinetic parameters using model fitting as well as model free isoconversional methods. The thermolytic pathways were also suggested, which involves decomposition followed by ignition. All the three complexes had coordination number ten and showed multistep decompositions. In order to evaluate the response of rapid heating, ignition delay （Di） measurements were undertaken. The activation energies for ignition were found to decrease in the order： Nd〉Pr〉Ce.展开更多
Objective:To investigate the chemical compositions and antimicrobial potentials of the essential oils and oleoresins obtained from fresh and dried Mentha longifolia L.Methods:Gas chromatography and gas chromatography-...Objective:To investigate the chemical compositions and antimicrobial potentials of the essential oils and oleoresins obtained from fresh and dried Mentha longifolia L.Methods:Gas chromatography and gas chromatography-mass spectrometer techniques were used to determine the profiling of the essential oils and oleoresins.In order to determine the antimicrobial efficacy of the volatile oil and oleoresins,the pathogenic fungus Aspergillus niger(1884),Aspergillus flavus(2479),Fusarium monoliforme(1893),Fusarium graminearum(2088)and Penicillium viridicatum(2007)were undertaken whereas four pathogenic bacteria Bacillus subtilis(1790),Staphylococcus aureus(3103)(Gram-positive),Escherichia coli(1672),Pseudomonas aeruginosa(1942)(Gram-negative)were selected for the present study.Food poisoned,inverted Petri plate,agar well diffusion and disk diffusion methods were employed for investigating antimicrobial potentials.Results:Piperitenone oxide,an oxygenated monoterpene,dominated the chemical compositions of essential oils and oleoresins whose compositions varied from 23.5%-87.8%.Both essential oils showed good antifungal activities against Aspergillus and Fusarium species.The antibacterial investigations revealed that Gram-positive bacteria were more sensitive to the essential oils.Conclusions:Drying the fresh herbal materials influences the chemical contents and the biological activities of the essential oils and oleoresins.Such results indicate that essential oils of Mentha longifolia L.can be possible candidates for further investigations to isolate and characterize their active principles as possible new natural preservatives.展开更多
文摘The nitrate complexes of cerium, praseodymium and neodymium with 1,10-phenanthroline （phen） of general formula [Ln（phen）2（NO3）2（H2O）2]·NO3 （where, Ln=Ce, Pr and Nd） were prepared and characterized by X-ray crystallography. Thermolysis of these complexes was investigated by simultaneous thermogravimetry （TG） and differential thermal analysis （DTA）. Isothermal TG was taken to evaluate the kinetic parameters using model fitting as well as model free isoconversional methods. The thermolytic pathways were also suggested, which involves decomposition followed by ignition. All the three complexes had coordination number ten and showed multistep decompositions. In order to evaluate the response of rapid heating, ignition delay （Di） measurements were undertaken. The activation energies for ignition were found to decrease in the order： Nd〉Pr〉Ce.
基金Supported by the University Grants Commission(Granted No.F.17-28/2008 SA-I).
文摘Objective:To investigate the chemical compositions and antimicrobial potentials of the essential oils and oleoresins obtained from fresh and dried Mentha longifolia L.Methods:Gas chromatography and gas chromatography-mass spectrometer techniques were used to determine the profiling of the essential oils and oleoresins.In order to determine the antimicrobial efficacy of the volatile oil and oleoresins,the pathogenic fungus Aspergillus niger(1884),Aspergillus flavus(2479),Fusarium monoliforme(1893),Fusarium graminearum(2088)and Penicillium viridicatum(2007)were undertaken whereas four pathogenic bacteria Bacillus subtilis(1790),Staphylococcus aureus(3103)(Gram-positive),Escherichia coli(1672),Pseudomonas aeruginosa(1942)(Gram-negative)were selected for the present study.Food poisoned,inverted Petri plate,agar well diffusion and disk diffusion methods were employed for investigating antimicrobial potentials.Results:Piperitenone oxide,an oxygenated monoterpene,dominated the chemical compositions of essential oils and oleoresins whose compositions varied from 23.5%-87.8%.Both essential oils showed good antifungal activities against Aspergillus and Fusarium species.The antibacterial investigations revealed that Gram-positive bacteria were more sensitive to the essential oils.Conclusions:Drying the fresh herbal materials influences the chemical contents and the biological activities of the essential oils and oleoresins.Such results indicate that essential oils of Mentha longifolia L.can be possible candidates for further investigations to isolate and characterize their active principles as possible new natural preservatives.
