| 1. |
- Stoica, L., et al.
(författare)
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Membrane-Less Biofuel Cell Based on Cellobiose Dehydrogenase (Anode)/Laccase (Cathode) Wired via Specific Os-Redox Polymers
- 2009
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Ingår i: Fuel Cells. - : Wiley. - 1615-6854 .- 1615-6846. ; 9:1, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- A membrane-free biofuel cell (BFC) is reported based on enzymes wired to graphite electrodes by means of Os-complex modified redox polymers. For the anode cellobiose dehydrogenase (CDH) is used as a biocatalyst whereas for the cathode a laccase was applied. This laccase is a high-potential laccase and hence able to reduce O-2 to H2O at a formal potential higher than +500 mV versus Ag/AgCl. In order to establish efficient electrochemical contact between the enzymes and graphite electrodes electrodeposition polymers containing Os-complex with specifically designed monomer compositions and formal potentials of the coordinatively bound Os-complex were synthesised and used to wire the enzymes to the electrodes. The newly designed CDH/Os-redox polymer anode was characterised at different pH values and optimised with respect to the nature of the polymer and the enzyme-to-polymer ratio. The resulting BFC was evaluated running on beta-lactose as a fuel and air/O-2 as an oxidising agent. The power output, the maximum current density and the electromotor force (E-emf) were found to be affected by the pH value, resulting in a maximum power output of 1.9 mu W cm(-2) reached at pH 4.3, a maximum current density of about 13 mu A cm(-2) at pH 3.5, and the highest E-emf approaching 600 mV at pH 4.0.
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| 2. |
- Li, Jian, et al.
(författare)
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Range compression and waveform optimization for MIMO radar : a Cramér-Rao bound based study
- 2008
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Ingår i: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 56:1, s. 218-232
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Tidskriftsartikel (refereegranskat)abstract
- A multi-input multi-output (MIMO) radar system, unlike standard phased-array radar, can transmit via its antennas multiple probing signals that may be correlated or uncorrelated with each other. This waveform diversity offered by MIMO radar enables superior capabilities compared with a standard phased-array radar. One of the common practices in radar has been range compression. We first address the question of "to compress or not to compress" by considering both the Cramer-Rao bound (CRB) and the sufficient statistic for parameter estimation. Next, we consider MIMO radar waveform optimization for parameter estimation for the general case of multiple targets in the presence of spatially colored interference and noise. We optimize the probing signal vector of a MIMO radar system by considering several design criteria, including minimizing the trace, determinant, and the largest eigenvalue of the CRB matrix. We also consider waveform optimization by minimizing the CRB of one of the target angles only or one of the target amplitudes only. Numerical examples are provided to demonstrate the effectiveness of the approaches we consider herein.
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| 3. |
- Stoica, Leonard, et al.
(författare)
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Electrochemical investigation of cellobiose dehydrogenase from new fungal sources on Au electrodes
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 20:10, s. 2010-2018
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Tidskriftsartikel (refereegranskat)abstract
- Following previous electrochemical investigations of cellobiose dehydrogenase (CDH), the present investigation reports on the initial screening of the electrochemistry of three new CDHs, two from the white rot basidiomycetes Trametes villosa and Phanerochaete sordida and one from the soft rot ascomycete Myriococcum thermophilum, for their ability to directly exchange electrons with 10 different alkanethiol-modified Au electrodes. Direct electron transfer (DET) between the enzymes and some of the modified Au electrodes was shown, both, in the presence and in the absence of cellobiose. However, the length and the head functionality of the alkanethiols drastically influenced the efficiency of the DET reaction and also influenced the effect of pH on the biocatalyfic/redox currents, suggesting the importance of structural/sequence differences between these CDH enzymes. In this respect, the white rot CDHs exhibit excellent biocatalytic and redox currents, whereas for the soft rot CDH the DET communication is much less efficient. Cyclic voltammograms indicate that the heme domain of the CDHs is the part of the enzymes that most readily exchanges electrons with the electrode. However, for R sordida CDH on 11-mercaptoundecanol or dithiopropionic acid-modified Au electrodes, a second voltammetric wave was noticed suggesting that for some orientations of the enzyme, DET communication with the FAD cofactor can also be obtained. (c) 2004 Elsevier B.V. All rights reserved.
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| 4. |
- Stoica, Leonard, et al.
(författare)
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Third-generation biosensor for lactose based on newly discovered cellobiose dehydrogenase
- 2006
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 78:2, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the principle and characteristics of a biosensor for lactose based on a third-generation design involving cellobiose dehydrogenase. As resulted from a previous comparative study (submitted manuscript), the novelty of this lactose biosensor is based on highly efficient direct electron transfer between two newly discovered cellobiose dehydrogenases (CDH), from the white rot fungi Trametes villosa and Phanerochaete sordida, and a solid spectrographic graphite electrode. CDH was immobilized on the electrode surface (0.073 cm(2)) by simple physical adsorption, and the CDH-modified electrode was next inserted into a wall-jet amperometric cell connected on-line to a flow injection setup (0.5 mL(.)min(-1)). The P. sordida CDH-based lactose biosensor, proved to be the better one, has a detection limit for lactose of 1 mu M, a sensitivity of 1100 mu A(.)mM(-1.)cm(-2), a response time of 4 s (the time required to obtain the maximum peak current), and a linear range from 1 to 100 mu M lactose (correlation coefficient 0.998). The simplicity of construction and analytical characteristics make this CDH-based lactose biosensor an excellent alternative to previous lactose biosensors reported in the literature or commercially available. The CDH-lactose sensor was used to quantify the content of lactose in pasteurized milk, buttermilk, and low-lactose milk, using the standard addition method. No effects of the samples matrixes were observed. The operational stability of the sensor was tested for 11 h by continuous injection of 100 mu M lactose (290 injections). The final signal of the sensor was maintained at 98% of its initial signal, with a low standard deviation of 1.72 (RSD 2.41%).
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