Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scali...Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching fiRrates from the pulp and paper industry, The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.展开更多
Cymbopogon citratus, better known as lemongrass, is a plant commonly used for culinary purposes. It is known to contain the compound citronellal, which is responsible for the lemon-scent of many of the plants of the g...Cymbopogon citratus, better known as lemongrass, is a plant commonly used for culinary purposes. It is known to contain the compound citronellal, which is responsible for the lemon-scent of many of the plants of the genus Cymbopogon. A chloroform extract of Cymbopogon citratus was screened to determine its free radical scavenging activities. Three different methods were used to test the antioxidant activity of the extract, including FRAP assay (Ferric reducing antioxidant potential), DPPH radical scavenging assay (1,1-diphenyl-2-picryl hydrazyl radical reducing power methods), and β-carotene bleaching assay. Cymbopogon citratus showed low radical scavenging activities compared to ascorbic acid, gallic acid and quercetin. The results obtained suggest that Cymbopogon citratus is best appreciated for its refreshing aroma and delicate taste, but has little to offer as a source of antioxidants.展开更多
Around 85% of the cases of Tuberculosis (TB) are pulmonary in origin and the routine diagnosis usually depends on sputum microscopy. The conventional direct Ziehl-Nelson (ZN) staining technique has been found to have ...Around 85% of the cases of Tuberculosis (TB) are pulmonary in origin and the routine diagnosis usually depends on sputum microscopy. The conventional direct Ziehl-Nelson (ZN) staining technique has been found to have a low sensitivity. The main objective of the study was to verify whether the bleach concentration method increases the sensitivity of sputum smear microscopy for AFB or not and also to see whether the first single morning sample alone is sufficient and better than the three pooled samples after bleach concentration followed by ZN staining. A total of 365 samples were studied from 131 clinically suspected cases of pulmonary TB which included sputum (112), gastric aspirate (5), endotracheal tube washing (2), and bronchial lavage (12). All these samples were processed for conventional ZN staining and Bleach concentration method followed by ZN staining. An increase in positivity was observed in all the cases after using the bleach concentration method and the most significantly useful was that in the case of first morning sputum samples where it increased from 11.6% to 41.96%. Bleach concentration is a simple, cheap and easily available method and also very safe because it kills the Mycobacteria in the process. Its positivity rate is better as compared to direct conventional ZN staining.展开更多
β-Carotene belongs to a group of more than 600 compounds,jointly called as carotenoids.It has numerous biological functions in the human body and because human is not able to synthesize any of them,it is necessary to...β-Carotene belongs to a group of more than 600 compounds,jointly called as carotenoids.It has numerous biological functions in the human body and because human is not able to synthesize any of them,it is necessary to supply these valuable compounds with food or pharmaceuticals.Rising,therefore,market demand stimulates the development of its diverse production methods.Originallyβ-carotene was recovered from plants by physicochemical extraction and mainly from carrots.Nowadaysβ-carotene is mainly produced through chemical synthesis.But quite recently biotechnology makes a great approach towardβ-carotene production as bioactive compounds of natural origin reveal higher bioaccessibility and higher consumer trust on market.展开更多
基金This work was supported by Vinnova and the Knowledge Foundation in Sweden.
文摘Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching fiRrates from the pulp and paper industry, The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.
文摘Cymbopogon citratus, better known as lemongrass, is a plant commonly used for culinary purposes. It is known to contain the compound citronellal, which is responsible for the lemon-scent of many of the plants of the genus Cymbopogon. A chloroform extract of Cymbopogon citratus was screened to determine its free radical scavenging activities. Three different methods were used to test the antioxidant activity of the extract, including FRAP assay (Ferric reducing antioxidant potential), DPPH radical scavenging assay (1,1-diphenyl-2-picryl hydrazyl radical reducing power methods), and β-carotene bleaching assay. Cymbopogon citratus showed low radical scavenging activities compared to ascorbic acid, gallic acid and quercetin. The results obtained suggest that Cymbopogon citratus is best appreciated for its refreshing aroma and delicate taste, but has little to offer as a source of antioxidants.
文摘Around 85% of the cases of Tuberculosis (TB) are pulmonary in origin and the routine diagnosis usually depends on sputum microscopy. The conventional direct Ziehl-Nelson (ZN) staining technique has been found to have a low sensitivity. The main objective of the study was to verify whether the bleach concentration method increases the sensitivity of sputum smear microscopy for AFB or not and also to see whether the first single morning sample alone is sufficient and better than the three pooled samples after bleach concentration followed by ZN staining. A total of 365 samples were studied from 131 clinically suspected cases of pulmonary TB which included sputum (112), gastric aspirate (5), endotracheal tube washing (2), and bronchial lavage (12). All these samples were processed for conventional ZN staining and Bleach concentration method followed by ZN staining. An increase in positivity was observed in all the cases after using the bleach concentration method and the most significantly useful was that in the case of first morning sputum samples where it increased from 11.6% to 41.96%. Bleach concentration is a simple, cheap and easily available method and also very safe because it kills the Mycobacteria in the process. Its positivity rate is better as compared to direct conventional ZN staining.
基金the framework of the COST Action-EUROCAROTEN CA15136,with the aim of the exchange and development of knowledge between European researchers working on carotenoids.
文摘β-Carotene belongs to a group of more than 600 compounds,jointly called as carotenoids.It has numerous biological functions in the human body and because human is not able to synthesize any of them,it is necessary to supply these valuable compounds with food or pharmaceuticals.Rising,therefore,market demand stimulates the development of its diverse production methods.Originallyβ-carotene was recovered from plants by physicochemical extraction and mainly from carrots.Nowadaysβ-carotene is mainly produced through chemical synthesis.But quite recently biotechnology makes a great approach towardβ-carotene production as bioactive compounds of natural origin reveal higher bioaccessibility and higher consumer trust on market.
