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511.
Ala-Kleme T Mäkinen P Ylinen T Väre L Kulmala S Ihalainen P Peltonen J 《Analytical chemistry》2006,78(1):82-88
Electrochemiluminescence (ECL) of aromatic Tb(III) chelates at thin insulating film-coated electrodes provides a means for extremely sensitive detection of Tb(III) chelates and also of biologically interesting compounds if these chelates are used as labels in bioaffinity assays. The suitability of silicon electrodes coated with thermally grown silicon dioxide film as disposable working electrodes in sensitive time-resolved ECL measurements is demonstrated, and a rapid electrochemiluminoimmunoassay (ECLIA) of human C-reactive protein (hCRP) is described. Tb(III) chelate labels can be detected almost down to picomolar level, and the calibration curve of these labels covers more than 6 orders of magnitude of chelate concentration. The calibration curve of the present immunometric hCRP assay was found to be linear over a wide range, approximately 4 orders of magnitude of hCRP concentration, the detection limit of the protein being 0.3 ng mL(-1) (mean background + 2SD) on CV values of about 10-30%, depending on the immunoassay incubation time. In the ECLIA measurements, different incubation times were tested from 15 min (giving above-mentioned performance) to as short as only 2 min, which still gave successful results with approximately 20,000 times better detection limit levels than traditional commercial assay methods. During the ECLIA process, also the Si electrode surface morphology was also investigated by atomic force microscope monitoring. 相似文献
512.
Wood ash (3.1, 3.3 or 6.6 tonnes dry weight ha− 1) was used to fertilize two drained and forested peatland sites in southern Sweden. The sites were chosen to represent the Swedish peatlands that are most suitable for ash fertilization, with respect to stand growth response. The fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the forest floor, measured using opaque static chambers, were monitored at both sites during 2004 and 2005 and at one of the sites during the period 1 October 2007-1 October 2008. No significant (p > 0.05) changes in forest floor greenhouse gas exchange were detected. The annual emissions of CO2 from the sites varied between 6.4 and 15.4 tonnes ha− 1, while the CH4 fluxes varied between 1.9 and 12.5 kg ha− 1. The emissions of N2O were negligible. Ash fertilization increased soil pH at a depth of 0-0.05 m by up to 0.9 units (p < 0.01) at one site, 5 years after application, and by 0.4 units (p < 0.05) at the other site, 4 years after application. Over the first 5 years after fertilization, the mean annual tree stand basal area increment was significantly larger (p < 0.05) at the highest ash dose plots compared with control plots (0.64 m2 ha− 1 year− 1 and 0.52 m2 ha− 1 year− 1, respectively). The stand biomass, which was calculated using tree biomass functions, was not significantly affected by the ash treatment. The groundwater levels during the 2008 growing season were lower in the high ash dose plots than in the corresponding control plots (p < 0.05), indicating increased evapotranspiration as a result of increased tree growth. The larger basal area increment and the lowered groundwater levels in the high ash dose plots suggest that fertilization promoted tree growth, while not affecting greenhouse gas emissions. 相似文献
513.
Henrik Pettersson Tadeusz Gruszecki Roman Bernhard Leif Hggman Mikhail Gorlov Gerrit Boschloo Tomas Edvinsson Lars Kloo Anders Hagfeldt 《Progress in Photovoltaics: Research and Applications》2007,15(2):113-121
A multicell is presented as a tool for testing material components in encapsulated dye‐sensitized solar cells. The multicell is based on a four‐layer monolithic cell structure and an industrial process technology. Each multicell plate includes 24 individual well‐encapsulated cells. A sulfur lamp corrected to the solar spectrum has been used to characterize the cells. Efficiencies up to 6·8% at a light‐intensity of 1000 W/msu2 (up to 7·5% at 250 W/m2) have been obtained with an electrolyte solution based on γ‐butyrolactone. Additionally, a promising long‐term stability at cell efficiencies close to 5% at 1000 W/m2 has been obtained with an electrolyte based on glutaronitrile. The reproducibility of the cell performance before and after exposure to accelerated testing has been high. This means that the multicell can be used as an efficient tool for comparative performance and stability tests. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
514.
Lisbeth Larsson Martin Ferm Asa Kasimir-Klemedtsson Leif Klemedtsson 《Nutrient Cycling in Agroecosystems》1998,51(1):41-46
Ammonia (NH3) and nitrous oxide (N-2O) emissions were measured in the field for three months from three different herbage mulches and from bare soil, used as a control. The mulches were grass with a low N-content (1.15% N in DM), grass with a high N-content (2.12% N in DM) and alfalfa with a high N-content (4.33% N in DM). NH3 volatilization was measured using a micrometeorological technique. N-2O emissions were measured using closed chambers. NH3 and N-2O emissions were found to be much higher from the N-rich mulches than from the low-N grass and bare soil, which did not differ significantly. Volatilization losses of NH3 and N-2O occurred mainly during the first month after applying the herbage and were highest from wet material shortly after a rain. The extent of NH3-N losses was difficult to estimate, due to the low frequency of measurements and some problems with the denuder technique, used on the first occasions of measurements. Nevertheless, the results indicate that NH3-N losses from herbage mulch rich in N can be substantial. Estimated losses of NH3-N ranged from the equivalent of 17% of the applied N for alfalfa to 39% for high-N grass. These losses not only represent a reduction in the fertilizer value of the mulch, but also contribute appreciably to atmospheric pollution. The estimated loss of N-2O-N during the measurement period amounted to 1% of the applied N in the N-rich materials, which is equivalent to at least 13 kg N-2O-N ha-1 lost from alfalfa and 6 kg ha-1 lost from high-N grass. These emission values greatly exceed the 0.2 kg N-2O-N ha-1 released from bare soil, and thus contribute to greenhouse gas emissions. 相似文献
515.
Yu-Kai Huang Heyin Chen Leif Nyholm 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(43):2306829
The development of “anode-free” lithium-metal batteries with high energy densities is, at present, mainly limited by the poor control of the nucleation of lithium directly on the copper current collector, especially in conventional carbonate electrolytes. It is therefore essential to improve the understanding of the lithium nucleation process and its interactions with the copper substrate. In this study, it is shown that diffusion of lithium into the copper substrate, most likely via the grain boundaries, can significantly influence the nucleation process. Such diffusion makes it more difficult to obtain a great number of homogeneously distributed lithium nuclei on the copper surface and thus leads to inhomogeneous electrodeposition. It is, however, demonstrated that the nucleation of lithium on copper is significantly improved if an initial chemical prelithiation of the copper surface is performed. This prelithiation saturates the copper surface with lithium and hence decreases the influence of lithium diffusion via the grain boundaries. In this way, the lithium nucleation can be made to take place more homogenously, especially when a short potentiostatic nucleation pulse that can generate a large number of nuclei on the surface of the copper substrate is applied. 相似文献
516.
Yuan Qu Sylvain Barjon Leif H Skibsted Giovanni Barone Lilia Ahrné 《International Journal of Dairy Technology》2023,76(3):597-606
The influence of partial acidification of skim milk (SM) using glucono-δ-lactone (GDL), citric acid (CA) or lactic acid (LA), on physicochemical properties (e.g. viscosity and calcium balance) of ultrafiltration (UF) retentates produced at 10 and 55°C was investigated. Ultrafiltration retentates produced using CA showed a significantly lower amount (P < 0.05) of ionic calcium and higher apparent viscosity than GDL and LA. Regardless of the acid used, total calcium concentration and apparent viscosity of streams were modified compared with SM, which impaired UF overall performance. Specifically, CA at 10°C and GDL at 55°C, both reduced the permeate flux when compared to the other acids. 相似文献
517.
Dr. Patrick Werner Dr. Patrick Schuenke Dr. Oxana Krylova Heike Nikolenko Prof. Dr. Matthias Taupitz Dr. Leif Schröder 《ChemMedChem》2022,17(13):e202100764
Glycosaminoglycans (GAGs) are highly negatively charged macromolecules with a large cation binding capacity, but their interaction potential with exogeneous Gd3+ ions is under-investigated. These might be released from chelates used as Gadolinium-based contrast agents (GBCAs) for clinical MR imaging due to transmetallation with endogenous cations like Zn2+. Recent studies have quantified how an endogenous GAG sequesters released Gd3+ ions and impacts the thermodynamic and kinetic stability of some GBCAs. In this study, we investigate and compare the chelation ability of two important GAGs (heparin and chondroitin sulfate), as well as the homopolysaccharides dextran and dextran sulfate that are used as models for alternative macromolecular chelators. Our combined approach of MRI-based relaxometry and isothermal titration calorimetry shows that the chelation process of Gd3+ into GAGs is not just a long-range electrostatic interaction as proposed for the Manning model, but presumably a site-specific binding. Furthermore, our results highlight the crucial role of sulfate groups in this process and indicate that the potential of a specific GAG to engage in this mechanism increases with its degree of sulfation. The transchelation of Gd3+ ions from GBCAs to sulfated GAGs should thus be considered as one possible explanation for the observed long-term deposition of Gd3+ in vivo and related observations of long-term signal enhancements on T1-weighted MR images. 相似文献
518.
Dr. Manuela Kowalczyk Dominic Kamps Prof. Yaowen Wu Leif Dehmelt Prof. Perihan Nalbant 《Chembiochem : a European journal of chemical biology》2022,23(4):e202100582
Cells process information via signal networks that typically involve multiple components which are interconnected by feedback loops. The combination of acute optogenetic perturbations and microscopy-based fluorescent response readouts enables the direct investigation of causal links in such networks. However, due to overlaps in spectra of photosensitive and fluorescent proteins, current approaches that combine these methods are limited. Here, we present an improved chemo-optogenetic approach that is based on switch-like perturbations induced by a single, local pulse of UV light. We show that this approach can be combined with parallel monitoring of multiple fluorescent readouts to directly uncover relations between signal network components. We present the application of this technique to directly investigate feedback-controlled regulation in the cell contraction signal network that includes GEF-H1, Rho and Myosin, and functional interactions of this network with tumor relevant RhoA G17 mutants. 相似文献