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31.
Endoscopic examination of the upper gastrointestinal (GI) tract in dogs and cats is a relatively recent development. It was just over 20 years ago, in 1978, that the first series report of GI endoscopy in dogs and cats was presented. In those initial days, endoscopy was truly a novelty, and the primary uses for endoscopes were to retrieve foreign objects or visualize the esophagus and stomach. It was not until the mid-1980s that technology and training made gastroduodenoscopy standard practice. The evolution in endoscopic technology has also mirrored the evolution in computers and imaging modalities. The original fiberoptic endoscopes, although still available, are giving way to video endoscopy and digital imaging capabilities that provide spectacular images and an ability to generate hard copy images for medical records, teaching purposes, and research data that was previously not possible.  相似文献   
32.
With the rapid rise in site-specific data collection, many research efforts have been directed towards finding optimal sampling and analysis procedures. However, the absence of widely available high quality precision agriculture data sets makes it difficult to compare results from separate experiments and to assess the optimality and applicability of procedures. To provide a tool for spatial data experimentation, we have developed a spatial data generator that allows users to produce data layers with given spatial properties and a response variable (e.g. crop yield) dependent upon user specified functions. Differences in response functions within fields can be simulated by assigning different models to regions in coordinate-(x and y) or feature space (multidimensional space of attributes that may have an influence on response). Noise, either unexplained variance or sensor error, can be added to all spatial layers. Sampling and interpolation error is modeled by sampling a continuous data layer and interpolating values at unsampled locations. The program has been successfully tested for up to 15000 grid points, 10 features and 5 models. As an illustration of the potential uses of generated data, the effect of sampling density and kriging interpolation on neural network prediction of crop yield was assessed. Yield prediction accuracy was highly related (correlation coefficient 0.98) to the accuracy of the interpolated layers indicating that unless data are sampled at very high densities relative to their geostatistical properties, one should not attempt to build highly accurate regression functions using interpolated data. By allowing users to generate large amounts of data with controlled complexity and features, the spatial data generator should facilitate the development of improved sampling and analysis procedures for spatial data.  相似文献   
33.
Relationship between soil CO2 concentrations and forest-floor CO2 effluxes   总被引:3,自引:2,他引:3  
To better understand the biotic and abiotic factors that control soil CO2 efflux, we compared seasonal and diurnal variations in simultaneously measured forest-floor CO2 effluxes and soil CO2 concentration profiles in a 54-year-old Douglas fir forest on the east coast of Vancouver Island. We used small solid-state infrared CO2 sensors for long-term continuous real-time measurement of CO2 concentrations at different depths, and measured half-hourly soil CO2 effluxes with an automated non-steady-state chamber. We describe a simple steady-state method to measure CO2 diffusivity in undisturbed soil cores. The method accounts for the CO2 production in the soil and uses an analytical solution to the diffusion equation. The diffusivity was related to air-filled porosity by a power law function, which was independent of soil depth. CO2 concentration at all depths increased with increase in soil temperature, likely due to a rise in CO2 production, and with increase in soil water content due to decreased diffusivity or increased CO2 production or both. It also increased with soil depth reaching almost 10 mmol mol−1 at the 50-cm depth. Annually, soil CO2 efflux was best described by an exponential function of soil temperature at the 5-cm depth, with the reference efflux at 10 °C (F10) of 2.6 μmol m−2 s−1 and the Q10 of 3.7. No evidence of displacement of CO2-rich soil air with rain was observed.Effluxes calculated from soil CO2 concentration gradients near the surface closely agreed with the measured effluxes. Calculations indicated that more than 75% of the soil CO2 efflux originated in the top 20 cm soil. Calculated CO2 production varied with soil temperature, soil water content and season, and when scaled to 10 °C also showed some diurnal variation. Soil CO2 efflux and concentrations as well as soil temperature at the 5-cm depth varied in phase. Changes in CO2 storage in the 0–50 cm soil layer were an order of magnitude smaller than measured effluxes. Soil CO2 efflux was proportional to CO2 concentration at the 50-cm depth with the slope determined by soil water content, which was consistent with a simple steady-state analytical model of diffusive transport of CO2 in the soil. The latter proved successful in calculating effluxes during 2004.  相似文献   
34.
β-chitin was isolated from marine waste, giant Humboldt squid Dosidicus gigas, and further converted to nanofibers by use of a collider machine under acidic conditions (pH 3). The FTIR, TGA, and NMR analysis confirmed the efficient extraction of β-chitin. The SEM, TEM, and XRD characterization results verified that β-chitin crystalline structure were maintained after mechanical treatment. The mean particle size of β-chitin nanofibers was in the range between 10 and 15 nm, according to the TEM analysis. In addition, the β-chitin nanofibers were converted into films by the simple solvent-casting and drying process at 60 °C. The obtained films had high lightness, which was evidenced by the CIELAB color test. Moreover, the films showed the medium swelling degree (250–290%) in aqueous solutions of different pH and good mechanical resistance in the range between 4 and 17 MPa, depending on film thickness. The results obtained in this work show that marine waste can be efficiently converted to biomaterial by use of mild extractive conditions and simple mechanical treatment, offering great potential for the future development of sustainable multifunctional materials for various industrial applications such as food packaging, agriculture, and/or wound dressing.  相似文献   
35.
Enzyme treatment technologies in textile processing have become commonly-applied techniques for the modification of fabric-handle appearance, and other surface and mechanical characteristics of fabrics. Most studies have focused on understanding the impact of enzyme treatments on the fabric preparation, dyeing, and finishing processes of woven fabrics, whilst only limited research has been reported regarding any enzymatic effects on the surface and handproperties of knitted fabrics. The aim of this study was to analyze the effects of two different enzymes Trichoderma reesei whole cellulase, and enriched (EGIII) endoglucanase cellulase, at three different enzyme dosages on 100 % cotton interlock knitted fabric. This was in order to evaluate certain surface properties such as pilling, friction. and geometrical roughness. Furthermore, the compression and tactile properties of knitted fabric were also analyzed. The results show that treatment conditions with enzyme Trichoderma reesei whole cellulase had the more pronounced effect on the surface properties compared to the enriched EGIII enzymes. In general, it can be concluded that both types of enzymes improved the surface properties and hand when compared with the silicone softener-treated reference sample of interlock knitted fabric, as is statistically confirmed by one-way analysis of variance.  相似文献   
36.
Serum amyloid A proteins (SAA) are very sensitive acute phase proteins, displaying multiple isoforms in plasma and different body fluids. They are currently under investigation as biomarkers of diseases. The aim of the present study was to compare the concentration and isoform expression of SAA in serum and milk of cows with bacteriologically negative milk (control group) and naturally occurring Staphylococcus aureus (S. aureus) subclinical mastitis (subclinical mastitis group). Somatic cell count (SCC) and bacteriological analyses were performed to establish the control and subclinical mastitis group. SAA concentration was evaluated using a commercial ELISA kit, while expression of different isoforms (serum A-SAA and milk M-SAA3 isoforms) was visualized by denaturing isoelectrical focusing and immunoblotting. The SAA concentrations in sera and milk of cows in the subclinical mastitis group were three and 100 times higher than in those from the control group of cows, respectively. Cows in the subclinical mastitis group had more acidic SAA isoforms in serum with the most prominent one at pI 5.5. This isoform was not detected in sera from the control group. Milk samples in the subclinical mastitis group contained abundant highly alkaline M-SAA3 isoforms and most of the serum isoforms, except for that at pI 5.5. In the subclinical mastitis group SAA isoforms with equivalent pI as serum isoforms accounted for 20% of the total SAA concentration in milk. There were significant differences in the concentrations and isoform patterns of SAA in serum and milk between the control and subclinical mastitis groups of cows. Also, we demonstrated that serum SAA isoforms were not transferred to milk proportion to their plasma content.  相似文献   
37.
We conducted a root-exclusion experiment in a 125-year-old boreal black spruce (Picea mariana (Mill.) BSP) stand in 2004 to quantify the physical and biological controls on temporal dynamics of the rhizospheric (R(r)) and heterotrophic (R(h)) components of soil respiration (R(s)). Annual R(r), R(h) and estimated moss respiration were 285, 269 and 57 g C m(-2) year(-1), respectively, which accounted for 47, 44 and 9% of R(s) (611 g C m(-2) year(-1)), respectively. A gradual transition from R(h)-dominated (winter, spring and fall) to R(r)-dominated (summer) respiration was observed during the year. Soil thawing in spring and the subsequent increase in soil water content (theta) induced a small and sustained increase in R(h) but had no effect on R(r). During the remainder of the growing season, no effect of theta was observed on either component of R(s). Both components increased exponentially with soil temperature (T(s)) during the growing season, but R(r) showed greater temperature sensitivity than R(h) (Q(10) of 4.0 and 3.0, respectively). Temperature-normalized variations in R(r) were highly correlated with eddy covariance estimates of gross ecosystem photosynthesis, and the correlation was greatest when R(r) was lagged by 24 days. Within diurnal cycles, variations in T(s) were highly coupled to variations in R(h) but were significantly decoupled from R(r). The patterns observed at both time scales strongly suggest that the flow of photosynthates to the rhizosphere is a key driver of belowground respiration processes but that photosynthate supply may control these processes in several ways.  相似文献   
38.
The gut microbiota is composed of a diverse population of obligate and facultative anaerobic microorganisms which are shown to influence host metabolism and immune homeostasis. This study investigated the effects of virgin coconut oil on the weekly fasting glycaemia, daily food and water intake and weekly body mass gain over 16 weeks, as well as the changes in composition of gut microbiota in both non-diabetic and alloxan-induced diabetic rats. Although the intake of virgin coconut oil did not decrease the diabetes-induced hyperglycemia, it affected the secondary parameters, such as food and water intake and average body mass gain. Furthermore, its potential to positively affect the fecal microbiome was proved, since it significantly increased the abundance of probiotic bacteria, such as Lactobacillus, Allobaculum and Bifidobacterium species.  相似文献   
39.
This study discusses a novel approach for fabrication of floating photocatalyst which can be efficiently exploited for photodegradation of dyes in aqueous solutions. A fabrication of the floating photocatalyst consisted of two steps: transformation of the poly(ε-caprolactone) beads (PCLb) into poly(ε-caprolactone) foam (PCLf) with porous structure in supercritical carbon-dioxide and subsequent loading of PCLf with TiO2 nanoparticles (NPs). Morphological characterization of the PCLf before and after TiO2 NPs loading was carried out by FESEM. The presence of titanium on the surface and inside the PCLf was detected by EDX. Photocatalytical activity of the floating photocatalyst was investigated in aqueous solution of textile dyes C.I. Acid Orange 7 (AO7) and C.I. Basic Yellow 28 (BY28) which were exposed to lamp that simulates the sun light. In addition to sustainable floatability for a long period of time, developed floating photocatalyst exhibited high rate of photodegradation since the complete discoloration of AO7 and BY28 solutions and photocatalysts alone occurred after 300 and 180 min of illumination, respectively. Its photocatalytic activity was preserved after three repeated photodegradation cycles with unchanged chemical structure that was confirmed by FTIR analysis.  相似文献   
40.
An elevated concentration of uranium in the water of some springs in the Permo-Triassic sedimentary rocks of the Visok region, south-eastern slopes of the Stara Planina, eastern Serbia, is interpreted based on geological, hydrogeological and hydrochemical data. Uranium concentration in groundwater was first examined whilst exploring for uranium minerals as an energy resource. The purpose of a later hydrogeological investigation was assessment of a safe drinking water supply to a planned ski-centre hotel. The maximum contaminant level for uranium, recommended by the World Health Organization (WHO), is 15 μg/L. This work reviews and interprets the naturally elevated uranium in springs from the Permo-Triassic sediments of Visok, focusing on geological, hydrogeological, hydrogeochemical and other factors of uranium contamination. Uranium distribution in groundwater from Permo-Triassic aquifers was studied by taking groundwater, spring sediment and rock samples. The varied mobility of uranium depends largely on lithology, which also controls the chemistry of groundwater. The investigation results have shown that sulfate–calcium groundwater is a suitable facilitator of uranium mobility with a high migration coefficient of 0.77. Uranium concentrations in this water were up to 41 μg/L, with a Sa/Sr mass ratio of around 20, and a mineral content of about 0.5 g/L. The hydrochemistry was characteristically transitional Eh and pH neutral. Elevated uranium in groundwater has been reported globally and may be compared.  相似文献   
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