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Reduction Treatment (reduction + treatment)
Selected AbstractsEffect of reduction/oxidation treatment on blue photorefraction in In:Fe:Cu:LiNbO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2010Suhua Luo Abstract In:Fe:Cu:LiNbO3 crystals with reduced/oxidized treatments were prepared by the Czochralski method. The defect structure was analyzed by the UV-Visible absorption spectra. The blue photorefractive properties, such as the refractive index change, response time, recording sensitivity, dynamic range as well as two-wave coupling gain coefficient, were also investigated at 488 nm wavelength using the two-wave coupling experiment. Comparing the as-grown and oxidized In:Fe:Cu:LiNbO3 crystals, the reduced sample has the highest recording sensitivity and largest dynamic range. Meanwhile, the high diffraction efficiency is still maintained. Experimental results definitely show that reduction treatment is an effective method to improve the blue photorefractive performance of In:Fe:Cu:LiNbO3 crystals. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Trophic control of grassland production and biomass by pathogensECOLOGY LETTERS, Issue 2 2003Charles E. Mitchell Abstract Current theories of trophic regulation of ecosystem net primary production and plant biomass incorporate herbivores, but not plant pathogens. Obstacles to the incorporation of pathogens include a lack of data on pathogen effects on primary production, especially outside agricultural and forest ecosystems, and an apparent inability to quantify pathogen biomass. Here, I report the results of an experiment factorially excluding foliar fungal pathogens and insect herbivores from an intact grassland ecosystem. At peak in control plots, 8.9% of community leaf area was infected by pathogens. Disease reduction treatment dramatically increased root production and biomass by increasing leaf longevity and photosynthetic capacity. In contrast, herbivory reduction had no detectable effects at the ecosystem or leaf scale. Additionally, biomass of foliar fungal pathogens in the ecosystem was comparable with that of insect herbivores. These results identify pathogens as potential regulators of ecosystem processes and promote the incorporation of pathogens into trophic theory. [source] Aluminium Metal Matrix Composites Based on Biomorphic Silicon CarbideADVANCED ENGINEERING MATERIALS, Issue 10 2006A. Herzog Wood can be transformed into silicon carbide (SiC) ceramic by pyrolysing the wood to form a porous carbon template, infiltrating the template with SiO2 sol, and then performing a carbothermal reduction treatment. In this work, such highly-porous ceramised wood replicas were infiltrated with molten aluminium via squeeze casting, thus creating biomorphic metal-matrix composites (MMCs). The microstructure of these novel MMCs were characterised and the mechanical properties examined. [source] Analysis of degraded papers by non-destructive spectroscopic techniquesJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Marina Bicchieri Abstract Scientific approach to cultural heritage conservation is very important for cultural reasons and also in order to avoid mistakes in restoration work. Acidity and oxidation play a very important role in paper conservation. Deacidification is a widely used method to remove acidity on aged papers, but if a large amount of carbonyl groups is present in the paper, a strong deacidification can promote an alkali-catalysed ,-alkoxy elimination, leading to the breaking of the anhydroglucose ring in the cellulose chain. In this case, and also in the case of non-acidic but oxidised papers, a reduction treatment is necessary. Because of the high costs of restoration procedures, it is essential to determine whether the reduction treatment is a primary need. In this work we report a study, based on micron-scale space resolved Raman microscopy, infrared reflectance spectroscopy and atomic force microscopy, of differently degraded samples of paper. Non-treated and oxidised samples were investigated, as well as original ancient documents. The aim of this work is to achieve a better understanding of the degradation pattern of historical samples in order to be able to choose the most appropriate restoration treatment using non-destructive spectroscopic techniques. Analysis of the samples demonstrates that degradation processes occur mainly on fibrils and on the fibre wall, as shown also by atomic force microscopy measurements. Copyright © 2006 John Wiley & Sons, Ltd. [source] Improved surface-enhanced Raman scattering of polypyrrole electrodeposited on roughened substrates composed of Au,Ag bimetallic nanoparticlesJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Thomas C. Chuang Abstract We report here the first electrochemical method to prepare a roughened gold substrate with bimetallic silver and gold nanoparticles. First, a silver substrate was roughened by a triangular-wave oxidation,reduction cycle in 0.1 N HCl aqueous solutions. Silver-containing complexes were found in the solution after the ORC treatment. Then a gold substrate was subsequently roughened by a similar oxidation,reduction treatment in this solution. Scanning electron microscopy and atomic force microscopy reveal that the surface of the roughened gold was intrinsically modified with silver nanoparticles, which demonstrates two different kinds of deposition domains. Encouragingly, surface-enhanced Raman scattering of polypyrrole electrodeposited on the roughened gold substrate, modified with finer silver nanoparticles, exhibits an eightfold higher intensity. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fabrication of Silicon Nitride Nanoceramics and their Tribological PropertiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2010Jae-Hee Kim Si2N2O secondary phase-free, fully dense nano-Si3N4 ceramics (,97% of theoretical density) were developed by combining carbothermal reduction treatment and spark plasma sintering (SPS), and their tribological properties were investigated by subjecting to self-mated sliding under unlubricated conditions. Commercially available Si3N4 nanopowder was used as a starting material and phenolic resin was used for carbothermal reduction, which was conducted at 1450°C for 10 h. Fully densified Si2N2O phase-free Si3N4 ceramics with a wide range of grain size from 90 nm to 1.5 ,m were fabricated by varying SPS temperature from 1550° to 1750°C. The microstructure of the developed Si3N4 ceramics was changed from nano equi-axed at 1550°C to large elongated bimodal grain morphology at 1700° or 1750°C. The frictional behavior was not dependent on the microstructure, but the wear rate was strongly influenced such that it decreased by an order of magnitude (from 9.7 × 10,5 to 0.88 × 10,5 mm3/N·m) with decreasing grain size. The dominant wear mechanism was changed from the delamination of tribochemical layer for the ceramics with nano equi-axed grain microstructure to the fracture and grain pull-out for the ceramics with duplex microstructure. [source] Thiopropyl-agarose as a solid phase reducing agent for chemical modification of IgG and F(ab,)2BIOTECHNOLOGY PROGRESS, Issue 5 2008Natalia Ferraz Abstract Selective reduction of native disulfide bonds in immunoglobulins is one of the best methods for introducing reactive groups on to the protein surface. Additionally, the thiol groups so generated may allow oriented conjugation at a specific site of the immunoglobulin. Solid-phase reducing agents have many advantages over soluble ones (including ease of separation of excess reagent from reduced protein by filtration, and the potential for regeneration and multiple reuse). In this work we report a comparative study of the reduction of rabbit IgG and its F(ab,)2 fragments, with mercaptohydroxypropylether-agarose (thiopropyl-agarose), a solid phase reducing agent, and dithiothreitol. The effect of different parameters on the process, such as the amount of reducing agent, incubation period, and temperature, was assessed by titration of thiol groups and SDS-PAGE analysis. Optimized reduction with thiopropyl-agarose introduced six thiol groups in the F(ab,)2 fragment (mol/mol). Native IgG was less reactive, probably due to steric effects, as only an average of three thiol groups were introduced. However, by increasing reaction temperature from 22 to 37°C, six thiol groups could be introduced in native IgG (mol/mol). Reduction with dithiothreitol also introduced six thiol groups in F(ab,)2 fragments (mol/mol) but led to higher thiol content for the whole IgG. These results demonstrated that thiopropyl-agarose can be a very useful tool for exercising more precise control over the reduction treatment, and for selecting which disulfide bridges are to be broken. After 6 h incubation with reducing agent containing 8 and 16 ,moles SH per mg of protein, the resulting reduced IgG retained the same biological activity as the native immunoglobulin. The controlled modification of native disulfides achieved with thiopropyl-agarose will be useful for the development of soluble and insoluble immunoglobulin conjugates. [source] Nanofiltration of plasma-derived biopharmaceutical productsHAEMOPHILIA, Issue 1 2003T. Burnouf Summary. This review presents the current status on the use and benefits of viral removal filtration systems , known as nanofiltration , in the manufacture of plasma-derived coagulation factor concentrates and other biopharmaceutical products from human blood origin. Nanofiltration of plasma products has been implemented at a production scale in the early 1990s to improve margin of viral safety, as a complement to the viral reduction treatments, such as solvent,detergent and heat treatments, already applied for the inactivation of human immunodeficiency virus, hepatitis B and hepatitis C virus. The main reason for the introduction of nanofiltration was the need to improve product safety against non-enveloped viruses and to provide a possible safeguard against new infectious agents potentially entering the human plasma pool. Nanofiltration has gained quick acceptance as it is a relatively simple manufacturing step that consists in filtering protein solution through membranes of a very small pore size (typically 15,40 nm) under conditions that retain viruses by a mechanism largely based on size exclusion. Recent large-scale experience throughout the world has now established that nanofiltration is a robust and reliable viral reduction technique that can be applied to essentially all plasma products. Many of the licensed plasma products are currently nanofiltered. The technology has major advantages as it is flexible and it may combine efficient and largely predictable removal of more than 4 to 6 logs of a wide range of viruses, with an absence of denaturing effect on plasma proteins. Compared with other viral reduction means, nanofiltration may be the only method to date permitting efficient removal of enveloped and non-enveloped viruses under conditions where 90,95% of protein activity is recovered. New data indicate that nanofiltration may also remove prions, opening new perspectives in the development and interest of this technique. Nanofiltration is increasingly becoming a routine step in the manufacture of biopharmaceutical products. [source] Use of image analysis techniques for objective quantification of the efficacy of different hair removal methodsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2007S. Bielfeldt In the field of consumer-used cosmetics for hair removal and hair growth reduction, there is a need for improved quantitative methods to enable the evaluation of efficacy and claim support. Optimized study designs and investigated endpoints are lacking to compare the efficacy of standard methods, like shaving or plucking, with new methods and products, such as depilating instruments or hair-growth-reducing cosmetics. Non-invasive image analysis, using a high-performance microscope combined with an optimized image analysis tool, was investigated to assess hair growth. In one step, high-resolution macrophotographs of the legs of female volunteers after shaving and plucking with cold wax were compared to observe short-term hair regrowth. In a second step, images obtained after plucking with cold wax were taken over a long-term period to assess the time, after which depilated hairs reappeared on the skin surface. Using image analysis, parameters like hair length, hair width, and hair projection area were investigated. The projection area was found to be the parameter most independent of possible image artifacts such as irregularities in skin or low contrast due to hair color. Therefore, the hair projection area was the most appropriate parameter to determine the time of hair regrowth. This point of time is suitable to assess the efficacy of different hair removal methods or hair growth reduction treatments by comparing the endpoint after use of the hair removal method to be investigated to the endpoint after simple shaving. The closeness of hair removal and visible signs of skin irritation can be assessed as additional quantitative parameters from the same images. Discomfort and pain rating by the volunteers complete the set of parameters, which are required to benchmark a new hair removal method or hair-growth-reduction treatment. Image analysis combined with high-resolution imaging techniques is a powerful tool to objectively assess parameters like hair length, hair width, and projection area. To achieve reliable data and to reduce well known image-analysis artifacts, it was important to optimize the technical equipment for use on human skin and to improve image analysis by adaptation of the image-processing procedure to the different skin characteristics of individuals, like skin color, hair color, and skin structure. [source] Immediate effects of prescribed burning, chopping and clearing on runoff, infiltration and erosion in a shrubland area in Galicia (NW Spain)LAND DEGRADATION AND DEVELOPMENT, Issue 5 2008C. Fernández Abstract The immediate effects of three different fuel management treatments on runoff, infiltration and erosion were evaluated in a mixed heathland in Galicia (NW Spain). The treatments compared were: prescribed burning, shrub chopping and shrub clearing. Rainfall simulations were conducted immediately before and after fuel reduction treatments. A rainfall rate of 67,mm,h,1 was applied for 30,min to each runoff plot. Application of treatments significantly affected runoff and infiltration, but the parameter most affected by treatment was soil erosion, especially after prescribed burning. However, sediment yields measured immediately after treatments were low in all the cases, varying from 32,kg,ha,1 after shrub clearing to 248,kg,ha,1 after prescribed burning. In the rainfall simulation plots subjected to prescribed burning, the maximum temperatures reached at mineral soil surface during burns significantly affected soil losses. The organic layer remaining after treatments and soil moisture contents appeared to be critical variables in controlling runoff and erosion during the first rainfall event following fuel reduction treatments. When the remaining organic layer was removed just after treatments and a new rainfall simulation was carried out, mean infiltration rate trended to decrease and cumulative runoff and sediment yield tended to increase. The above information could be useful for determining whether fuel management prescriptions are compatible with fire hazard reduction and soil conservation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Behavioral Response of Resident Jamaican Birds to Dry Season Food Supplementation,BIOTROPICA, Issue 1 2006David R. Brown ABSTRACT We used plot-level manipulations and analyses to test the effects of food availability on the behavior and condition of resident dry-forest birds in Jamaica. Two control plots were monitored in each of 2 yr. Food was supplemented on five plots over 2 yr with piles of cut oranges distributed around plots, which served as a direct source of carbohydrates and water, and an indirect source of ground arthropods due to increased above-ground activity. We reduced ants on five plots over 2 yr; however, we found no difference in total ground arthropod biomass between control and reduction treatments, so we pooled these plots for analysis. We selected nine focal resident bird species for study of relative abundance, body condition, and breeding condition. Birds were sampled prior to, and 5 to 6 weeks after the initiation of treatments. Seven of nine species had higher relative abundance following food supplementation. Three species were recaptured more frequently in supplementation plots than in control plots. These abundance and persistence responses did not cause any changes in body condition. In one species, Bananaquit (Coereba flaveola), food supplementation resulted in higher concentrations of individuals in breeding condition. These results demonstrate a functional response to dry-season food availability and suggest a limiting mechanism. This study helps explain mechanisms by which bird populations respond to resource availability, and is the first successful plot-level food supplementation experiment for tropical forest birds. [source] | ||||||||||||||||