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1.
中试系统制备了杨木碱性过氧化氢机械浆。分别在水相 /有机溶剂相 /气相等条件下 ,使用乙酐处理杨木化机浆 (原浆及硼氢化钠还原后纸浆 ) ,分别抄造成 60g/m2 纸片 ,测定了不同时间紫外线照射后试样白度。运用返色值 (PCno .)和白度稳定效果 (BSE)等指标评价处理后浆料的光学稳定性。研究结果表明 ,有机溶剂相和气相乙酰化后的纸浆 ,光学稳定性的提高程度取决于乙酐用量和反应时间即乙酰化程度。通过乙酰化 ,可以获取光学完全稳定的杨木化机浆。紫外漫射反射光谱表明 ,杨木APMP机械浆光诱导返色的主要原因是纸浆木质素中羰基和酚羟基团吸收紫外光后变化形成发色结构所致。还原配合纸浆乙酰化处理 ,可能成为防止高得率纸浆返色的工业应用方法  相似文献   
2.
Bosco  Laura  Wan  Ho Yi  Cushman  Samuel A.  Arlettaz  Raphaël  Jacot  Alain 《Landscape Ecology》2019,34(1):105-117
Context

Herbicide treatments in viticulture can generate highly contrasting mosaics of vegetated and bare vineyards, of which vegetated fields often provide better conditions for biodiversity. In southern Switzerland, where herbicides are applied at large scales, vegetated vineyards are limited in extent and isolated from one another, potentially limiting the distribution and dispersal ability of organisms.

Objectives

We tested the separate and interactive effects of habitat amount and fragmentation on invertebrate abundance using a multi-scale framework, along with additional environmental factors. We identified which variables at which scales were most important in predicting patterns of invertebrate abundance.

Methods

We used a factorial design to sample across a gradient of habitat amount (area of vegetated vineyards, measured as percentage of landscape PLAND) and fragmentation (number of vegetated patches, measured as patch density PD). Using 10 different spatial scales, we identified the factors and scales that most strongly predicted invertebrate abundance and tested potential interactions between habitat amount and fragmentation.

Results

Habitat amount (PLAND index) was most important in predicting invertebrate numbers at a field scale (50 m radius). In contrast, we found a negative effect of fragmentation (PD) at a broad scale of 450 m radius, but no interactive effect between the two.

Conclusions

The spatial scales at which habitat amount and fragmentation affect invertebrates differ, underpinning the importance of spatially explicit study designs in disentangling the effects between habitat amount and configuration. We showed that the amount of vegetated vineyards has more influence on invertebrate abundance, but that fragmentation also contributed substantially. This suggests that efforts for augmenting the area of vegetated vineyards is more beneficial for invertebrate numbers than attempts to connect them.

  相似文献   
3.

Context

Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem.

Objectives

To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape.

Methods

Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses.

Results

We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator.

Conclusions

The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning.
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4.
As a key parameter in the management of fish populations, individual growth rate (GR) variations were examined in the European eel (Anguilla anguilla; > 150 mm) using extensive mark–recapture surveys in the lotic habitats of two small rivers of western France: the Frémur, supposed to be saturated, and at the same latitude, the Oir with densities fivefold lower than those of the Frémur. In both systems, generalised linear models were used to test whether spatiotemporal factors such as dominant habitat type or local density affect GR variability. In the presumed unsaturated system, the Oir, GR variability is mainly explained by a set of habitat suitability drivers (density, dominant habitat type). In the Frémur, GRs appear independent of differences in habitat density or productivity. Below saturation, an increase in density will decrease the GR through intraspecific competition. At saturation, intraspecific competition reaches such high levels that regardless of eel density and productivity, the resources available by individual are similar throughout the system. In these circumstances, the effect of density on growth was presumed undetectable. Despite these contrasted results, mean GRs observed in both catchments were closed (~20 mm·year?1). This is an unexpected result as GR is expected to be higher in unsaturated systems. This similarity could be explained by the difference between the two systems in terms of: (i) sex ratio (the Frémur is dominated by male, whereas the female is dominant in the Oir), (ii) habitat type distribution or (iii) possible interspecific competition (important salmonid populations in the Oir).  相似文献   
5.
Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested.  相似文献   
6.
Type material of the proteocephalidean cestodes Manaosia bracodemoca Woodland, 1935 and Paramonticellia itaipuensis Pavanelli et Rego, 1991 (both monotypic genera) as well as recently collected material of the latter species are redescribed. A close similarity between both species was observed: the shape of scoleces is identical, both possess a globular scolex with hidden suckers, a well-developed circular, horseshoe-shaped musculature surrounding suckers; the measurements of both taxa are also similar (scolex, suckers, young proglottides). Both cestodes possess a medullary ovary crossing the dorsal muscle layer and ending in the dorsal cortex, the testes are in the dorsal cortex and the cortical vitellarium is laterally situated. Both species parasitize the same fish host. Therefore Paramonticellia is considered a junior synonym of Manaosia and Paramonticellia itaipuensis becomes a junior synonym of Manaosia bracodemoca. An emended diagnosis of Manaosia, which is a monotypic genus, is provided.  相似文献   
7.
OBJECTIVE: To evaluate, by use of population pharmacokinetics, the disposition of marbofloxacin in the aqueous humor after IV administration in dogs and identify its potential usefulness in the prophylaxis and treatment of intraocular infection. ANIMALS: 63 dogs. METHODS: Dogs received a single dose of marbofloxacin (2 mg x kg(-1), IV) at various time intervals before cataract surgery. Aqueous humor and blood samples were collected at the beginning of surgery. Marbofloxacin concentrations were measured by high-pressure liquid chromatography. Data were analyzed with a nonlinear mixed-effect model and, by use of population pharmacokinetic parameters, the time course of aqueous humor concentration was simulated for single doses of 3, 4, and 5.5 mg x kg(-1) IV. Pharmacodynamic surrogate markers and measured aqueous humor concentrations were used to predict in vivo antimicrobial activity. RESULTS: A maximum marbofloxacin concentration of 0.41 +/- 0.17 microg x mL(-1) was reached in the aqueous humor 3.5 hours after IV administration. In the post-distributive phase, marbofloxacin disappeared from aqueous humor with a half-life of 780 minutes. The percentage penetration into the aqueous humor was 38%. Predictors of antimicrobial effects of marbofloxacin (2 mg x kg(-1), IV) indicated that growth of the enterobacteriaceae and certain staphylococcal species would be inhibited in the aqueous humor. Marbofloxacin administered IV at a dose of 5.5 mg x kg(-1) would be predicted to inhibit growth of Pseudomonas aeruginosa and all strains of staphylococci but would not eradicate streptococcal infections. CONCLUSIONS AND CLINICAL RELEVANCE: Marbofloxacin administered IV can penetrate the aqueous humor of canine eyes and may be suitable for prophylaxis or treatment of certain anterior chamber infections.  相似文献   
8.
Biological weapons are considered as mass destruction and terror weapons. Terrorism including bioterrorism is the major threat in the future conflicts for our nations. The aim of bioterrorism is more related to the potential disorganisation of the society than to the lethal effects of the agents used. The dramatic consequences cannot be discarded, especially if contagious agents such viral are used. The preparation of specific defence measures is a major challenge for our countries.

The knowledge acquired from the struggle against natural infectious diseases and recent events are essential to improve behaviours to face the biological weapon threats. The defence attitude is based on the anticipation of the threat, the management of the victims, and the restoration of the operational capabilities. This global defence attitude implies six important functions: (i) alert, (ii) detection and diagnosis, (iii) availability of pharmaceutical countermeasures such as vaccine, sera and anti-infectious medicine and products, (iv) medical management of victims, (v) training and information, (vi) research and development.

Passive and active immunoprevention and immuntherapy belong to the approaches discussed in the context of bioterrorism countermeasures. Further researches might be focused on these topics.  相似文献   

9.
We investigated the phenotype of the T cells (CD4+ and CD8+) that produced Th1 (IFN-gamma) and Th2 cytokines (IL-4 and IL-10) during the firsttwo weeks of experimental fasciolosis in rats. We also followed the kinetics of the cytokine and proliferative responses of hepatic mononuclear cells (HMNC) over the same period. We found that HMNC were more numerous in the infected animals than in the controls. The percentage of CD4+ cells increased significantly after infection, whereas the percentage of CD8+ cells did not change. Moreover, the frequency of the cells producing (CP) cytokine changed after infection. The frequency of CP IFN-gamma on 7 days postinfection (pi) was similar to that in control animals. However, the frequency of CP IFN-gamma was clearly lower on day 14 pi, whereas the frequency of CP IL-4 and CP IL-10 had increased. The CP IL-10-were mostly CD4+. Mitogenic stimulation (phorbol myristate acetate/ionomycin) of HMNC led to an increase in the amounts of the Th2 cytokines in the supernatant on days 7 and 14 pi, with the increase more pronounced on day 14. In contrast, IFN-gamma levels also increased by day 7 pi but then decreased to below control levels by day 14. In addition, HMNC proliferation in response to mitogen followed a similar pattern to IFN-gamma production. These findings suggested that, during the first 2 weeks of infection, F hepatica induced a transient ThO cytokine profile followed by downregulation of the cellular response and the induction of a Th2 cytokine profile.  相似文献   
10.
Ethoxylates of rapeseed oil and of methylated rapeseed oil were synthesized and tested as adjuvants for 2,4-D and phenmedipham. Provided they had less than 6 units of ethylene oxide (EO), 1.0 to 10 g litre(-1) ethoxylates in water induced droplet spreading on barley leaves. In an acetone-based medium all derivatives strongly promoted the foliar uptake of 2,4-D, with no clear influence of the ethoxylation degree. In the same medium there was a negative influence of ethoxylate chain length on the foliar uptake of phenmedipham. In a water-based medium, phenmedipham applied with rapeseed oil emulsified with ethoxylated (20 EO) rapeseed oil displayed uptake rates close to a commercial preparation. The same was true for phenmedipham applied with ethoxylated (2 EO) methylated rapeseed oil. In bioassays, phenmedipham prepared with methylated rapeseed oil emulsified with ethoxylated (20 EO) rapeseed oil was as efficacious on barley as a commercial formulation. The same was true for phenmedipham prepared with ethoxylated (2 EO) methylated rapeseed oil. However, neither rapeseed oil nor methylated rapeseed oil emulsified with ethoxylated (2 EO) methylated rapeseed oil conferred good efficacy to phenmedipham. Hence, ethoxylated rapeseed oil derivatives are promising adjuvants or formulants for herbicides.  相似文献   
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