The adsorption kinetics of a cationic polyelectrolyte onto a model negatively charged cellulose surface has been investigated. Two regimes have been distinguished. At low surface coverage, the ...adsorption is transport-limited while at higher surface coverage the incoming polymer experiences a blocking barrier of electrostatic nature. This barrier has been quantified and the respective roles of the polymer and surface charge have been assessed.
The reliability of a multi-state system is considered. The system is subject to both internal wear-out and external shocks causing damage that cumulates as shocks follow one another. As a consequence ...of this cumulating damage, the system wear-out process can be affected.
The study of the system is achieved by means of phase-type distributions, which are used to model: the inter-arrival times between shocks, the magnitude of the damage due to the shocks, and the lifetime distribution of the system between shocks. In the latter case, the phases of the phase-type distribution refer to the different degradation levels (‘states’) of the system.
The lifetime distribution of the system is affected by the shocks in different ways: if the cumulated damage after a shock exceeds q predefined thresholds, the system can no longer evolve in the first q least degraded levels; the corresponding phase-type distribution is then defined on the remaining phases. But after each shock causing no threshold to be exceeded, only the initial probability vector of the phase-type distribution is modified in order to account for a decrease in the expected residual lifetime of the system.
Two particular cases are studied. First, several thresholds on the cumulated damage can be exceeded following the occurrence of one shock; secondly, only one threshold at a time can be exceeded.
Grid stability affects the progression of loss of offsite power scenarios to the nuclear power plants, as the most dominant core-damage-inducing initiating event. The ever-increasing tendency toward ...integration of large-scale wind farms into the transmission systems drastically challenges their dynamic behavior.
In this study, we proposed a dynamic-probabilistic framework to evaluate the effect of wind penetration scenarios on the frequency of occurrence of LOOP to the NPPs. We developed 30 initial grid states, including 3 wind penetration percentages, 5 operational loading levels, in both optimal and normal power flows.
We estimated 150 GR-LOOP frequencies for 5 NPP locations upon 3Ph-Shc faults on the transmission lines. Extending from 1.3 × 10−7 to 9.6 × 10−5 (year)−1 for the safest to the riskiest situations, the mean GR-LOOP frequencies have been assessed as 1.74 × 10−5, 2.96 × 10−5, and 2.77 × 10−5 (year)−1, for grids with 0%, 10%, and, 20% penetration percentage of installed wind generation, respectively.
Our results indicate the undeniable influence of variations in the operational loadings and the wind penetration percentage on the GR-LOOP frequency, in addition to the NPPs’ locations. Such intensification effect was more pronounced in instantaneous frequencies of unique states than in the averaged ones. Furthermore, we observed more outstanding growth in the corresponding values of optimal cases. Our findings suggested that the reliability of the offsite grid to the NPPs be considered as a decision-making criterion, in addition to the existing security and economic issues in the grids with wind penetration.
•We evaluate the frequency of grid-related loss of offsite power to the nuclear power plants.•The occurrence frequency is significantly affected by the penetration percentage of wind farms.•The operational status of the pre-fault grid and optimal cases cause significant variations in the results.•The occurrence frequency varies with the change in the locations of nuclear power plants.•We suggest GR-LOOP frequency as a decision-making criterion in the grid security evaluation.
This paper describes a multi-scale approach for the modelling of the degradation of model cement pastes using reactive transport. It specifically aims at incorporating chemistry-transport feedback ...results from a pore-scale approach into a continuum description. Starting from a numerical representative elementary volume of the model cement paste, which was built according to extensive experimental dedicated chacarterizations, this paper provides three separate descriptions of two different degradations: leaching and carbonation. First, 2D pore-scale simulations are performed and predict degradation depths in very good agreement with experiments. Second, 3D pore scale descriptions of how the microstructre evolves provides accurate description of the evolution of transport properties through degradation. Finally, those latter results are incorporated as a feedback law between porosity and effective diffusion coefficient into a 1D continuum approach of reactive transport. This paper provides pore-scale explanations of why reactive transport modelling has encountered mitigated success when applied to cementitious materials, especially during carbonation or degradations consisting of precipitation reactions. In addition to that, different degradation modellings are in very good agreement with experimental observations.
•Results are based on accurate and dedicated experimental results without fitting parameters.•Modellings of leaching were in good agreement with experimental results.•3D modelling of carbonation brings key understanding of carbonation impact.•2D modellings of carbonation are in good agreement with experiments.•The exogeneous crust formation was explained based on microstructural features.
We present discrete adaptive bit loading algorithms for multicarrier systems with uniform (nonadaptive) power allocation operating in a frequency selective fading environment. The algorithms try to ...maximize the overall throughput of the system while guaranteeing that the mean bit error rate (BER) remains below a prescribed threshold. We also study the impact of imperfect subcarrier signal-to-noise ratio information on throughput performance. Results show that the proposed algorithms have approximately the same throughput and mean BER as the optimal allocation while having a significantly lower computational complexity relative to other algorithms with near-optimal allocations. Moreover, when compared with algorithms that employ approximations to water filling, the computational complexity is comparable while the overall throughput is closer to the optimum.
The transformation of living polymer chain‐ends is particularly well‐suited to synthesize end‐functionalized polymers. Herein, the development of a recent synthetic methodology is reported. High ...degrees of functionalization are obtained using alkyl chlorides bearing heteroatoms as functionalization agents. A mechanism involving complexation of the lithium counterion by the heteroatom of the reagent is proposed, based on the role of the heteroatom, the chloroalkyl derivative structure, and data reported in recent publications. Thus, ω‐functional polymers have been prepared by reacting the corresponding living anionic polymers with a chloroacetal, a chloroether and a dichloroether. The products have been characterized by size‐exclusion chromatography, 1H nuclear magnetic resonance (NMR) and 13C NMR. The degree of functionalization has been determined by 1H NMR.
DNA functionalised semiconductor metallic oxide electrodes have been developed for the direct electrochemical detection of DNA hybridization, without labelling or the introduction of a redox couple. ...Conductive CdIn(2)O(4) thin films with controlled properties were deposited on glass substrates using an aerosol pyrolysis technique. The films exhibit a polycrystalline microstructure with a surface roughness of 1.5 nm (r.m.s.) and an electrical resistivity ranging between 1 and 3 x 10(-3) Omega cm. These electrodes were functionalised using hydroxylation and silanisation steps, to allow the binding of DNA probe sequences (20 bases). The electrical detection of DNA hybridization with complementary sequences has been performed using electrochemical impedance spectrometry (EIS) measuring the variation of impedance before and after hybridization. Two set-ups were used, a standard set-up including three electrodes and a set-up including two symmetrical electrodes. In both configurations, a significant increase of the impedance modulus, more particularly of the real part of the impedance (160-225% according to the electrochemical cell used) has been obtained over a frequency range of 10-10(5)Hz. DNA hybridization has also been systematically confirmed using the fluorescence spectrometry. This study emphasizes the high sensitivity of the CdIn(2)O(4) as a working electrode for the detection of biological events occurring at the electrode surface.
Abstract This study analysed daily antimicrobial costs of Intensive Care Unit (ICU)-acquired, laboratory-confirmed bloodstream infection (BSI) per patient admitted to the ICU of a university ...hospital, based on prospectively collected data over a 4-year period (2003–2006). Costs were calculated based on the price of the agent(s) initiated on the first day of appropriate treatment and according to: (i) focus of infection; (ii) pathogen; and (iii) antimicrobial agent. The study included 310 adult patients who developed 446 BSI episodes. Mean overall daily antimicrobial cost was €114.25. Daily antimicrobial cost was most expensive for BSIs with unknown focus (€137.70), followed by catheter-related (€122.73), pulmonary (€112.80), abdominal (€98.00), wound (€89.21), urinary (€87.85) and other inciting focuses (€81.59). Coagulase-negative staphylococci were the most prevalent pathogens isolated. Treatment of BSIs caused by Candida spp. was the most costly. The daily antimicrobial costs per infected patient with multidrug-resistant BSI was ca. 50% higher compared with those without (€165.09 vs. €82.67; P < 0.001). Among the total of 852 prescriptions, β-lactam antibiotics accounted for approximately one-third of the overall daily cost of antimicrobial agents. The antibiotic cost associated with ICU-acquired, laboratory-confirmed BSI is significant and should be reduced by implementing infection control measures and preventive strategies.
Oversampled filter banks (OFBs) provide an overcomplete representation of their input signal. This paper describes how OFBs can be considered as error-correcting codes acting on real or complex ...sequences, very much like classical binary convolutional codes act on binary sequences. The structured redundancy introduced by OFBs in subband signals can be used to increase robustness to noise. In this paper, we define the notions of code subspace, syndrome, and parity-check polynomial matrix for OFBs. Furthermore, we derive generic expressions for projection-based decoding, suitable for the case when a simple second-order model completely characterizes the noise incurred by subband signals. We also develop a nonlinear hypotheses-test based decoding algorithm for the case when the noise in subbands is constituted by a Gaussian background noise and impulsive errors (a model that adequately describes the action of both quantization noise and transmission errors). Simulation results show that the algorithm effectively removes the effect of impulsive errors occurring with a probability of 10/sup -3/.
The paper reports on the influence of electrical resistivity of bio-modified transparent and conductive oxide (TCO) electrodes on the sensitivity to DNA hybridization in term of impedance variation. ...We have deposited pure cadmium indate (CdIn
2O
4) film electrodes on glass substrates by aerosol pyrolysis. By adjusting the film deposition conditions, films with a wide range of resistivity ranging between 4
×
10
−4 and 2
×
10
−3
Ω
cm were obtained. Using electrochemical impedance spectroscopy (EIS), we showed that the behaviour of bare films is typical of semiconductor electrode with flat band potentials depending on the film resistivity. Then we studied the electrochemical behaviour of the biomodified electrodes before and after DNA hybridization. The impedance variation due to DNA hybridization was particularly studied in the low frequency range where large and significant increases were observed. These increases were studied in term of calculated polarisation resistance
R
p. For all films,
R
p variation is potential dependant and is maximum between −0.1 and 0
V/ref. In this range of potential, the magnitude of this variation increases with the film resistivity. This behaviour is explained by the relationship between the field effect phenomenon, the
thickness of the space charge region and the film electrical resistivity. This work shows that, in the case of metallic semi-conductive oxide electrode, the sensitivity to the DNA detection increases with the electrode resistivity.
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