In a wetland ecosystem such as lowland ricefields, the anaerobic mineralization of organic matter is a key mechanism for nutrient recycling (Jørgensen 1982; Freney et al. 1982). In the process which involves several bacterial groups, sulfate reducers (Watanabe and Furusaka 1980; Widdel 1988; Ouattara and Jacq 1992; Nozoe 1997), methanogens (Asakawa and Hayano 1995; Dianou et al. 1997), sulfur and ferric ion reducers (Jacq et al. 1991) become active when the soil becomes anoxic (Amstrong 1969). Sulfate reducers are common in flooded soils (Watanabe and Furusaka 1980; Widdel 1988; Furusaka et al. 1991). Reported densities in rice soils ranged from 103 to 105 g-1 dry soils in Asia (Watanabe and Furusaka 1980) and from 102 to 109 g-1 dry soil in Sénégal (Ouattara and Jacq 1992). Among the sulfate reducers, the “classical” Desulfovibrio species are known to oxidize typical fermentation products such as hydrogen, lactate, pyruvate, and dicarboxylic acids (Widdel 1988). So far, data on the isolation and characterization of sulfate-reducing bacterial (SRB) strains from African rice paddy field soils study have been very limited. 相似文献
Alkaline residues of recycled paper production (ARRP) can be an alternative for correcting soil acidity and adding bases to Pinus taeda L. systems. Our aim was to investigate the effect of increasing doses of ARRP on tree, forest floor (litter and root), and soil composition in a 3-year-old Brazilian pine forest plantation. In 2007, ARRP treatments of 0, 10, 20, 30 and 40 T ha?1 were imposed. Tree growth and needle elemental composition were evaluated in 2008 and 2018; elemental composition of the trunk was evaluated in 2018. In 2017, accumulation and composition of litter layers were assessed: new litter, old litter, first and second sublayers of fragmented litter (Fr and Fm), and the humified layer (H); roots present in F and H layers were quantified (amount and elemental composition). In addition, soil chemical properties at different depths were evaluated in 2008, 2012, and 2017. The application of ARRP improved growth by ~?16% up to 20 T ha?1 after 10 years. Also, ARRP increased Ca concentration in needles, trunks, roots, and all litter fractions since Ca was a major component of ARRP. There was no change in total litter accumulation with ARRP application, but an increase in the humidified fraction was observed. Root growth was enhanced by ARRP, leading to great changes in root composition in Fr and H fractions. Changes in soil pH, Ca2+, and Al3+ were observed in the 0–10 cm soil layer. Findings suggest that application of ARRP to established pine forests has the potential for improving productivity.
Freshness is the main concern of seafood quality, and the principal method to evaluate seafood freshness is sensory evaluation. The aim of this work was to study the quality changes of cobia, Rachycentron canadum, under ice storage through sensory and physical analysis as well as bacterial counting of specific spoilage organisms (SSOs). In particular, the utilization of a quality index method (QIM) scheme was proposed. Samples stored for 0–30 d were analyzed with the QIM. Ten panelists observed and registered the changes occurring in the fish starting on day zero and ending when the fish were spoiled. After developing the scheme, 11 sensory attributes were described in 23 points, which detailed the appearance of skin, eyes, abdomen, gills, and flesh deterioration. The volatile nitrogen compound measurements and microbiological data of the SSOs determined a shelf‐life of 19 d for the samples. Sensory analysis showed a rejection point at 15.67 d of ice storage. The natural degradation of myofibrillar proteins and collagen was observed during ice storage. In conclusion, a shelf‐life of 15 d was defined for raw cobia stored on ice. 相似文献
Hexagonal mesoporous silica modified with carboxylic acid (SiAc) has been obtained by reaction between chloroacetic acid and 3-aminopropyltrimethoxysilane, which was immobilized on porous material by a sol-gel process in the presence of an n-dodecylamine template. SiAc was characterized by TG, FT-IR, (29)Si NMR, (13)C NMR, SEM, surface charge density, surface area and porous diameter, which proved that the carboxylic group was chemically bonded to an inorganic structure, and the material presented a nanometric structure with spheres <50 nm and porous diameter of 10 nm. Herbicides 2,4-D and picloram were anchored on SiAc porous gel to produce the materials named SiD and SiPi, respectively. The controlled release of picloram from the SiAc was less than that of 2,4-D. After 26 days of releasing, 4.43 × 10(-5) mol L(-1) of picloram was delivered by SiPi, and 5.0 × 10(-5) L(-1) was released from the SiD in 30 days. 相似文献
I was evaluated the effect of seven different combinations of temperature, air velocity, and relative air humidity on the frequency and duration of eating, drinking, resting, cannibalism, dust bathing, scratching, ground pecking, shivering, and stretching behaviors of turkeys at three different ages. The combinations tested of temperature, relative air humidity, and air velocity were, respectively: 1 (22 °C, 50%, 1 m/s); 2 (26.2 °C, 73.2%, 0.45 m/s); 3 (26.6 °C, 71.2%, 1 m/s); 4 (28.9 °C, 72%, 1.4 m/s); 5 (31.1 °C, 85%, 0.45 m/s); 6 (34.1 °C, 82.1%, 1 m/s); and 7 (34.4 °C, 82.1%, 1.4 m/s) for three ages of birds (61, 96, and 131 days of age). Seven birds were housed per pen, at a density of 3 males/m2, totaling 147 birds in the entire experiment. Each combination was applied for 5 days. The data were analyzed considering the number of times the bird performed the behavior and the time it performed (in seconds). Each pen was considered a repetition. A comparison of the medians was used to compare the treatments by each age. The results showed that young birds were more likely to suffer from the combination of low temperature and high air velocity, reducing their frequency of normal behaviors. Increased humidity at a low temperature raised the frequency of scratching, shivering, and cannibalism behaviors leading to poorer bird welfare. It is recommended that the temperature, relative air humidity, and air velocity combination of 26.6 °C; 71.2%; and 1 m/s, respectively, for young birds, and 22 °C; 50%; and 1 m/s, respectively, for older birds should be used.
The tomato chlorosis virus (ToCV), transmitted by whitefly species of the genera Bemisia and Trialeurodes in a semipersistent manner, causes significant losses in solanaceous crops including tomato (Solanum lycopersicum) and sweet pepper (Capsicum annuum). Worldwide reports of natural and experimental infection of sweet pepper plants with ToCV are contradictory, raising the question of whether the critical factor determining infection is related to the susceptibility of sweet pepper cultivars or the genetics of virus isolates. In this work, ToCV isolates obtained from different hosts and geographical origins were biologically and molecularly analysed, transmitted by B. tabaci MEAM1 and MED, and the reaction of different sweet pepper cultivars was evaluated under different environmental conditions. Brazilian ToCV isolates from tomato, potato (S. tuberosum), S. americanum, and Physalis angulata did not infect plants of five sweet pepper cultivars when transmitted by B. tabaci MEAM1. Temperatures did not affect the sweet pepper susceptibility to tomato-ToCV isolates from São Paulo, Brazil, and Florida, USA. However, sweet pepper-ToCV isolates from Spain and São Paulo, Brazil, were transmitted efficiently to sweet pepper plants by B. tabaci MEAM1 and MED. Although the results indicated that ToCV isolates from naturally infected sweet pepper plants seem to be better adapted to plants of C. annuum, phylogenetic analyses based on the complete nucleotide sequences of RNA1 and RNA2 as well as the p22 gene did not reveal significant nucleotide differences among them. Additional studies are needed to identify intrinsic characteristics of ToCV isolates that favour infection of sweet pepper plants. 相似文献
The aim of this work is the experimental evaluation of the residual strength of composite laminates under compression after low velocity impact. Different kinds of delaminations, partial, embedded and through-the-width, were studied. Carbon-fibre reinforced epoxy composite was used and the experimental tests were performed on [0]16, [0, 90, 0, 90]2S and [0i, 90i]s with i=2, 3, 4, 5, using a drop-weight-testing machine. The impacted plates were inspected by the ultrasonic C-Scan to evaluate the size and the shape of the delamination. Results show that the presence of delamination decreases the compressive strength. The stacking sequence and laminate thickness were verified to have a remarkable influence on the value of the residual compressive strength, and play an important role on the observed buckling failure modes. 相似文献
Oblique cutting differs from orthogonal cutting by an inclination given to the knife edge, which induces several changes on
tool geometry, cutting forces, as well as on the quality of machined surfaces. In this work, a pressure bar was used during
oblique cutting to reduce the occurrence of torn grain. The effects of cutting depth, rake angle, and oblique angle on cutting
forces and surface quality were studied. Surface topography, cell damage and wetting properties were used to assess surface
quality. All force components were increased by increasing cutting depth and decreasing rake and oblique angles. The lateral
force, however, increased as the oblique angle increased. The surface roughness increased with increasing the lateral cutting
force. Higher cutting depths and oblique angles tended to provide higher surface roughness, while higher rake angles tended
to reduce surface roughness. The pressure bar was not always able to completely prevent the occurrence of defects when cutting
against the grain. The occurrence of machining defects increased at higher cutting depths and oblique angles. As the rake
angle decreased, the type of machining defect tended to change from torn grain to slight fuzzy grain. Moreover, the best wetting
properties were obtained at lower rake angles, as they induced higher surface roughness. A 25° rake angle, a 30° oblique angle,
and thinner cutting depths should be preferred to reduce dependence on ulterior sanding. 相似文献
Subluxation of the proximal interphalangeal joint is a rare and little studied condition in horses. We describe the case of a 12-year-old mare with bilateral dorsal subluxation of the proximal interphalangeal joint of the hind feet. Tenectomy of the medial digital flexor was performed in both limbs, and the patient showed signs of recovery within 14 days. Goniometry of the proximal interphalangeal joints 10 months after surgery showed diminution of 5° for the proximal interphalangeal axis of the left hind limb. However, no change was found for the joint angle of the right limb. Even so, the patient's gait and radiographic results were normal, and clinical abnormalities such as joint clicking and swelling were no longer observed. 相似文献
Feces of 70 diarrhoeic and 230 non‐diarrhoeic domestic cats from São Paulo, Brazil were investigated for enteropathogenic (EPEC), enterohaemorrhagic (EHEC) and enterotoxigenic (ETEC) Escherichia coli types. While ETEC and EHEC strains were not found, 15 EPEC strains were isolated from 14 cats, of which 13 were non‐diarrhoeic, and one diarrhoeic. None of 15 EPEC strains carried the bfpA gene or the EPEC adherence factor plasmid, indicating atypical EPEC types. The EPEC strains were heterogeneous with regard to intimin types, such as eae‐θ (three strains), eae‐κ (n = 3), eae‐α1 (n = 2), eae‐ι (n = 2), one eae‐α2, eae‐β1 and eae‐η each, and two were not typeable. The majority of the EPEC isolates adhered to HEp‐2 cells in a localized adherence‐like pattern and were positive for fluorescence actin staining. The EPEC strains belonged to 12 different serotypes, including O111:H25 and O125:H6, which are known to be pathogens in humans. Multi locus sequence typing revealed a close genetic similarity between the O111:H25 and O125:H6 strains from cats, dogs and humans. Our results show that domestic cats are colonized by EPEC, including serotypes previously described as human pathogens. As these EPEC strains are also isolated from humans, a cycle of mutual infection by EPEC between cats and its households cannot be ruled out, though the transmission dynamics among the reservoirs are not yet understood clearly. 相似文献
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