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111.
112.
Nitrous oxide (N2O) flux measurements from an Irish spring barley field managed under conventional and reduced tillage and different N fertilizer
applications at the Teagasc Oak Park Research Centre were made for two consecutive seasons. The aim was to investigate the
efficacy of reduced tillage and reduced N fertilizer on seasonal fluxes and emission factors of N2O and to study the relationship between crop yield and N-induced fluxes of N2O. The soil is classified as a sandy loam with a pH of 7.4 and a mean organic carbon and nitrogen content at 15 cm of 19 and
1.9 g kg−1 dry soil, respectively. Reduced tillage had no significant effect on N2O fluxes from soils or crop grain yield. Multiple regression analysis revealed that soil moisture and an interaction between
soil moisture and soil nitrate are the main significant factors affecting N2O flux. The derived emission factor was 0.6% of the applied N fertilizer, approximately 50% of the IPCC default EF of 1.25%
used by the Irish EPA to estimate GHG or the IPCC revised EF of 0.9%. This resulted in huge overestimations of 2,275 and 1,050
tonnes of N2O-N for using the old and revised IPCC default factors respectively. By reducing the applied nitrogen fertilizer by 50% compared
to the normal field rate, N2O emissions could be reduced by 57% with no significant decrease on grain yield or quality. This was consistent over the 2 years
of measurements. 相似文献
113.
Linnéa Rosenbaum Per Löwenborg Håkan Johansson 《Circuits, Systems, and Signal Processing》2010,29(1):103-133
This paper introduces two classes of cosine-modulated causal and stable filter banks (FBs) with near perfect reconstruction
(NPR) and low implementation complexity. Both classes have the same infinite-length impulse response (IIR) analysis FB but
different synthesis FBs utilizing IIR and finite-length impulse response (FIR) filters, respectively. The two classes are
preferable for different types of specifications. The IIR/FIR FBs are preferred if small phase errors relative to the magnitude
error are desired, and vice versa. The paper provides systematic design procedures so that PR can be approximated as closely
as desired. It is demonstrated through several examples that the proposed FB classes, depending on the specification, can
have a lower implementation complexity compared to existing FIR and IIR cosine-modulated FBs (CMFBs). The price to pay for
the reduced complexity is generally an increased delay. Furthermore, two additional attractive features of the proposed FBs
are that they are asymmetric in the sense that one of the analysis and synthesis banks has a lower computational complexity
compared to the other, which can be beneficial in some applications, and that the number of distinct coefficients is small,
which facilitates the design of FBs with large numbers of channels. 相似文献
114.
Effect of interesterified fat mixtures on certain lipid indices in experimental fat metabolism disturbance 总被引:1,自引:0,他引:1
Groups of adult Wistar male and female rats were fed isoenergetically for a three and a six weeks period either with synthetic lipogenic diet containing 5% and 20% fat mixtures (in which sunflower oil and lard were blended according to the ratio of 35:65) or with the same synthetic diet containing the mixture of sunflower oil and interesterified lard in a similar ratio. A control group received a normal diet for 6 weeks, whereas one of the experimental groups (fed with the 20% fat mixture in the lipogenic diet for 6 weeks) was given the normal diet for an additional two weeks period. After the feeding periods had been completed serum HDL-C levels and the total lipid, triglyceride, total cholesterol, free fatty acid levels were determined in serum and liver. The distribution of fatty acids in liver and heart muscle was also evaluated. In comparison to the control values it has been found: 1. Consumption of the lipogenic diet which is known to increase the serum total lipid and total cholesterol content induced in male rats a smaller augmentation in these indices when consuming the 20% fat mixture with a P/S ratio approaching the ideal 1 values, than in case of a 5% fat mixture consumption. In case of female rats, considerable increases of the serum values, could be observed at both fat consumption levels. The serum triglyceride and HDL-C contents decreased for all experimental groups. 2. The total lipid and triglyceride content of the liver increased in a high degree, the fatty liver syndrome was developed--more rapidly in males than in females. The total lipid, triglyceride and total cholesterol contents of the liver of male rats exceeded those of females by 15-30%. 3. The interesterification of the lard component of fat mixture resulted in lipid indices similar to those without interesterification, or in certain cases, they were found to be even slightly more favourable, i.e. the biological effect of the technological change proved to be adequate. 4. After a two weeks regeneration period the serum values of the male rats approached closer the normal control values than those of the females which were decreasing from a very high level but the degree of decrease was greater for them than for the male rats. The lipid content of the liver showed similar values.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
115.
Mellegård H From C Christensen BE Granum PE 《International journal of food microbiology》2011,149(3):218-225
Bacillus cereus is an endospore-forming bacterium able to cause food-associated illness. Different treatment processes are used in the food industry to reduce the number of spores and thereby the potential of foodborne disease. Chitosan is a polysaccharide with well-documented antibacterial activity towards vegetative cells. The activity against bacterial spores, spore germination and subsequent outgrowth and growth (the latter two events hereafter denoted (out)growth), however, is poorly documented. By using six different chitosans with defined macromolecular properties, we evaluated the effect of chitosan on Bacillus cereus spore germination and (out)growth using optical density assays and a dipicolinic acid release assay. (Out)growth was inhibited by chitosan, but germination was not. The action of chitosan was found to be concentration-dependent and also closely related to weight average molecular weight (Mw) and fraction of acetylation (FA) of the biopolymer. Chitosans of low acetylation (FA = 0.01 or 0.16) inhibited (out)growth more effectively than higher acetylated chitosans (FA = 0.48). For the FA = 0.16 chitosans with medium (56.8 kDa) and higher Mw (98.3 kDa), a better (out)growth inhibition was observed compared to low Mw (10.6 kDa) chitosan. The same trend was not evident with chitosans of 0.48 acetylation, where the difference in activity between the low (19.6 kDa) and high Mw (163.0 kDa) chitosans was only minor. In a spore test concentration corresponding to 102-103 CFU/ml (spore numbers relevant to food), less chitosan was needed to suppress (out)growth compared to higher spore numbers (equivalent to 108 CFU/ml), as expected. No major differences in chitosan susceptibility between three different strains of B. cereus were detected. Our results contribute to a better understanding of chitosan activity towards bacterial spore germination and (out)growth. 相似文献
116.
NDF, ADF, ‘cellulose’ and IVOMD residues, from feeding value determinations, were prepared from some forages, including straw, alkali-treated straw, grass and lucerne samples. The crude protein, cellulose, hemicellulose, uronic acid, Klason lignin, lignin and ash contents of these residues and the corresponding original forage samples were determined together with the relative composition of the neutral sugar constituents after acid hydrolysis. Cellulose, hemicellulose and Klason lignin were the main components in the NDF fractions but substantial amounts of crude protein (1–6%) also remained. Cellulose and Klason lignin were the main components in the ADF fractions, but 7–14% of the fractions was hemicellulose and 1–4% crude protein. Cellulose was the main component in the ‘cellulose’ fractions, but they also contained 8–13% hemicellulose, 2–7% Klason lignin and 2–11% ash. The composition of the IVOMD residues showed that cellulose and hemicellulose had been dissolved to about the same amounts (70–80%) and that most of the Klason lignin remained. 相似文献
117.
Henrik Wiinikka Fredrik Weiland Esbjörn Pettersson Olov Öhrman Per Carlsson Jesper Stjernberg 《Combustion and Flame》2014
In this paper submicron particles sampled after the quench during 200 kW, 2 bar(a) pressurised, oxygen blown gasification of three biomass fuels, pure stem wood of pine and spruce, bark from spruce and a bark mixture, have been characterised with respect to particle size distribution with a low pressure cascade impactor. The particles were also characterised for morphology and elemental composition by a combination of scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and high resolution transmission electron microscopy/energy dispersive spectroscopy/selected area electron diffraction pattern (HRTEM/EDS/SAED) techniques. The resulting particle concentration in the syngas after the quench varied between 46 and 289 mg/Nm3 consisting of both carbon and easily volatile ash forming element significantly depending on the fuel ash content. Several different types of particles could be identified from classic soot particles to pure metallic zinc particles depending on the individual particle relation of carbon and ash forming elements. The results also indicate that ash forming elements and especially zinc interacts in the soot formation process creating a particle with shape and microstructure significantly different from a classical soot particle. 相似文献
118.
Vamsi Krishna Palukuru Jani Peräntie Mikko Komulainen Timo Tick Heli Jantunen 《Journal of the European Ceramic Society》2010,30(2):389-394
A tunable microwave phase shifter composed of a low-sintering-temperature, screen-printable barium strontium titanate (BST) film and silver metallization was fabricated on an alumina substrate and co-fired at 900 °C for 3 h. The dielectric properties of the films were characterized in a frequency range of 0.8–8 GHz using scattering parameter measurements and a quasi-static coplanar waveguide transmission line model. The temperature dependency of the films was measured through capacitance measurements in a frequency range of 0.5–2.5 GHz. The figure of merit (phase shift/dB of insertion loss) of the phase shifter was found to be 14.6 at 3 GHz with an applied bias field strength of 2.5 V/μm. The performance of the phase shifter is briefly discussed and compared with other phase shifters fabricated by direct screen-printing of BST films. 相似文献
119.
This paper assesses the increase in demand and supply for forest biomass for heating in Norway in 2020. By then there is a political aim to double the national production of bioenergy from the level in 2008. The competitiveness of woody biomass in central and district heating is analyzed in a model selecting the least-cost heating technology and scale in municipalities given a set of constraints and under different fuels price scenarios. The supply of forest biomass from roundwood is estimated based on data of forest inventories combined with elasticities regarding price and standing volumes. The supply of biomass from harvesting residues is estimated in an engineering approach based on data from the national forest inventories and roundwood harvest. The results show how the production of bioenergy is affected by changes in energy prices and support schemes for bioenergy. One conclusion from the analyses is that the government target of 14 TWh more bioenergy by 2020 is not likely to be met by current technologies and policy incentives. The contribution of the analysis is the detailed presentation of the heat market potentials and technology choices combined with supply functions for both roundwood and harvesting residues. 相似文献
120.
An ultra-high pressure jet of water and air with simultaneous cement grouting is revolutionishing the practice of ground consolidation and foundation reinforcement. Swedish research has been studying this development, briefly explained here. The note report is based on a summary note issued by the Swedish Council for Building Research. 相似文献