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Sökning: db:Swepub > Mattiasson Bo > (2000-2004) > Engelska

  • Resultat 51-60 av 103
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51.
  • Lacayo, Martha, et al. (författare)
  • Degradation of toxaphene in water during anaerobic and aerobic conditions
  • 2004
  • Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 130:3, s. 437-443
  • Tidskriftsartikel (refereegranskat)abstract
    • The degradation of technical toxaphene in water with two kinds of bioreactors operating in sequence was studied. One packed bed reactor was filled with Poraver(R) (foam glass particles) running at anaerobic conditions and one suspended carrier biofilm reactor working aerobically. Chemical oxygen demand (COD), chloride, sulphate, pH, dissolved oxygen, total toxaphene and specific toxaphene isomers were measured. After 6 weeks approx. 87% of the total toxaphene was degraded reaching 98% by week 39. The majority of the conversion took place in the anaerobic reactor. The concentrations of toxaphene isomers with more chlorine substituents decreased more rapidly than for isomers with less chlorine substituents. (C) 2004 Elsevier Ltd. All rights reserved.
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52.
  • Leth, Suzanne, et al. (författare)
  • Engineered bacteria based biosensors for monitoring bioavailable heavy metals
  • 2002
  • Ingår i: Electroanalysis. - 1040-0397. ; 14:1, s. 35-42
  • Tidskriftsartikel (refereegranskat)abstract
    • This work presents an integrated analytical system based on immobilized engineered microorganisms and bioluminescence measurements for monitoring of bioavailable heavy metal ions (Cu being chosen as a model ion). A strain of microorganisms from Alcaligenes eutrophus (AE1239) was genetically engineered by inserting a luxCDABE operon from Vibrio fischeri under the control of a copper-induced promoter. As a result, copper ions induce bioluminescence, which is proportional to the concentration of the triggering ions, representing the basis of the design of the hereby described heavy metal biosensor. Microorganisms grown in two different media (Luria Broth and a modified mineral reconstitution medium/RM) were optimized and characterized in solution with regard to the influence of (growth media and cell density in order to obtain optimal bioluminescent signals. Next, the microorganisms were immobilized in polymer matrices, compatible with fiber optics and were characterized with regard to sensitivity, selectivity, detection limit and storage stability. The lowest detection limit (1 muM) was achieved with microorganisms cultivated from glycerol stock solutions in the RM media and immobilized in a calcium alginate matrix.
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53.
  • Li, YuCai, et al. (författare)
  • Application of shielding boronate affinity chromatography in the study of the glycation pattern of haemoglobin
  • 2002
  • Ingår i: Journal of Chromatography. B. - 1873-376X. ; 776:2, s. 149-160
  • Tidskriftsartikel (refereegranskat)abstract
    • Human haemoglobin (Hb) may appear in a number of glycated species. The glycation pattern of Hb using shielding boronate affinity chromatography (SBAC) has been studied in the present work. SBAC is a novel separation technique, which eliminates nonspecific boronate-protein interactions by introducing a so-called shielding reagent [1,2]. Two samples from Bio-Rad (Lyphochek(R))-one from normal persons' blood with relatively low HbA(1c) level (HbL) and the other from diabetic patients' blood with an elevated HbA(1c) level (HbH)-were used for the investigation. Glycated Hb (GHb) was separated from nonglycated Hb species using Tris as the shielding reagent. Two eluted peaks, eluted peak 1 (E1) and eluted peak 2 (E2), were obtained using a linear gradient elution with Tris. Several bands were observed on isoelectric focusing gel, which showed the same migration positions as Hb adducts, such as HbA(o), which is major Hb component containing two alpha chains and two beta chains; HbA(1c) which is post-translational glycation on the N-terminus of the beta chains of HbA(o); Foetal Hb (HbF), consisting of two alpha chains and two gamma chains; and glutathione Hb (also called HbSSG), which is the result from thiol-disulphide interchain exchange during oxidation of the thiol groups of Hb. In both HbL and HbH samples, E2 exhibited slightly higher amounts of HbF than E1. Electrospray-ionisation mass spectrometry showed that: (1) HbL-E1 was glycated with single glucose on both alpha and beta chains while no observable glycated chains were present in HbL-E2; (2) both HbH-E1 and HbH-E2 were glycated with single glucoses on both alpha and beta chains, however, compared with HbH-E1, HbH-E2 showed a higher relative intensity of the glycated beta chain and lower relative intensity of the glycated alpha chain; and (3) the degree of glycation increased with increasing glycation level of the sample. The amount of HbA(1c) presented in the eluted peaks was further determined using enzymatic digestion of glycated Hb by endoproteinase Glu-C and the subsequent separation and analysis of the digested peptides by reversed-phase high-performance liquid chromatography and capillary electrophoresis. The values of HbA(1c)/HbA(o) of the eluted peaks, i.e. HbL-E1, HbL-E2, HbH-E1 and HbH-E2, were 0.27, 0.19, 0.50 and 0.43, respectively. In both HbL and HbH samples, E1 contained higher amounts of HbA(1c) than E2. This study demonstrates the structural heterogeneity of GHb as well as the possibility of using SBAC to detect glycated species of Hb.
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54.
  • Liu, Jing, et al. (författare)
  • A volumetric meter for monitoring of low gas flow rate from laboratory-scale biogas reactors
  • 2004
  • Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 97:2-3, s. 369-372
  • Tidskriftsartikel (refereegranskat)abstract
    • A reliable and inexpensive device for measuring gas with low flow rates is described. The device works based on the principle of liquid displacement and is able to measure flows from 1 to 950 ml(.)h(-1). It also has improved counting logic and data processing capacity to avoid miscounting and provide a friendly interface for data display. (C) 2003 Elsevier B.V. All rights reserved.
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55.
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56.
  • Liu, Jing, et al. (författare)
  • Control of an anaerobic reactor towards maximum biogas production
  • 2004
  • Ingår i: Water Science and Technology. - 0273-1223. ; 50:11, s. 189-198
  • Tidskriftsartikel (refereegranskat)abstract
    • A new control strategy is introduced for operating anaerobic digestion processes efficiently at high load. The control system includes a cascade controller embedded into a rule-based supervisory system based on extremum-seeking control. The control system measures pH and biogas production rate and varies the organic load by manipulating the influent flow. Good control performances were achieved during the start-up and steady-state running operations and during rejection of disturbances. The control system can run the process under a high load condition and efficiently reject disturbances without explicit measurement of the influent characteristics.
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57.
  • Liu, Jing, et al. (författare)
  • Immobilised activated sludge based biosensor for biochemical oxygen demand measurement
  • 2000
  • Ingår i: Biosensors & Bioelectronics. - 1873-4235. ; 14:12, s. 883-893
  • Tidskriftsartikel (refereegranskat)abstract
    • A biochemical oxygen demand (BOD) sensor, based on an immobilised mixed culture of microorganisms in combination with a dissolved oxygen electrode, has been developed for the purpose of on-line monitoring of the biological treatment process for waste and wastewater. The sensor was designed for easy replacement of the biomembrane, thereby making it suitable for short-term use. The drawbacks of activated sludge based sensor, such as short sensor lifetime, were thereby circumvented. The sensor BOD measurements were carried out in the kinetic mode using a flow injection system, resulting in 25 s for one measurement followed by 4-8 min recovery time. Based on the results of normalised sensor responses, the OECD synthetic wastewater was considered to be a more suitable calibration solution in comparison with the GGA solution. Good agreement was achieved between the results of the sensor BOD measurement and those obtained from BOD5 analysis of a wastewater sample from a food-processing factory. Reproducibility of responses using one sensor was below +/-5.6% standard deviation. Reproducibility of responses using different sensors was within acceptable bias limits, viz. +/-15% standard deviation.
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58.
  • Liu, Jing, et al. (författare)
  • Microbial BOD sensors for wastewater analysis
  • 2002
  • Ingår i: Water Research. - 1879-2448. ; 36:15, s. 3786-3802
  • Tidskriftsartikel (refereegranskat)abstract
    • The field of biosensors for measuring biochemical oxygen demand (BOD) is reviewed. Particularly, BOD sensors constructed on the biofilm configuration are discussed regarding performance characteristics like linearity, response time, precision, agreement between BOD values obtained from the biosensors and the conventional 5-days test, as well as toxic resistance to various compounds and operational stability. The techniques for improving the agreement between the sensor BOD and BOD5 are described. Information provided also includes BOD biosensors based on respirometers and other measuring principles, the commercial BOD instruments, as well as the current limitations of BOD biosensor development.
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59.
  • Liu, Jing, et al. (författare)
  • Monitoring and control of an anaerobic upflow fixed-bed reactor for high-loading-rate operation and rejection of disturbances
  • 2004
  • Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 87:1, s. 43-53
  • Tidskriftsartikel (refereegranskat)abstract
    • A new control strategy has been introduced for operating anaerobic digestion processes efficiently at high load. The control system includes a cascade controller embedded into a rule-based supervisory system based on extremum-seeking control. Three process parameters, considered to be the most realistic variables for monitoring of the bioprocess, were selected (pH, biogas production rate, and the difference between the actual biogas flow and its setpoint). The control system examines these variables and varies the organic load by manipulating the influent flow. Good control performance was achieved during the start-up, during steady-state running operations, and during rejection of disturbances. The main advantages of this control approach can be attributed to its ability to adjust control parameters automatically, both for high-load operation and for rejection of disturbances. Furthermore, the influent flow can be tuned automatically according to variations in organic matter in the feed without the characteristics of the influent being considered. (C) 2004 Wiley Periodicals, Inc.
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60.
  • Liu, Jing, et al. (författare)
  • Monitoring of two-stage anaerobic biodegradation using a BOD biosensor.
  • 2003
  • Ingår i: Journal of Biotechnology. - 1873-4863. ; 100:3, s. 261-265
  • Tidskriftsartikel (refereegranskat)abstract
    • A previously developed biosensor for fast estimation of short-term biochemical oxygen demand (BODst) was used for off-line monitoring of intermediate products from the initial step of an anaerobic process in laboratory scale. Good agreement was generally achieved between the results from the biosensor method and the conventional 5-day test except for samples with high content of organic polymers. During the period of agreement between the measurement principles, good correlation was achieved between the biogas production rate and the organic loading rate. The results from this study demonstrate that BODst can be a successful monitoring parameter to achieve a better process control.
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  • Resultat 51-60 av 103

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