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排序方式: 共有1068条查询结果,搜索用时 15 毫秒
1.
F. L. Laksmana P. J. A. Hartman Kok H. Vromans H. W. Frijlink K. Van der Voort Maarschalk 《AAPS PharmSciTech》2009,10(3):732-742
Next to the coating formulation, process conditions play important roles in determining coating quality. This study aims to
develop an operational window that separates layering from agglomeration regimes and, furthermore, the one that leads to the
best coating quality in a fluidized bed coater. The bed relative humidity and the droplet size of the coating aerosol were
predicted using a set of engineering models. The coating quality was characterized using a quantitative image analysis method,
which measures the coating thickness distribution, the total porosity, and the pore size in the coating. The layering regime
can be achieved by performing the coating process at a certain excess of the viscous Stokes number (ΔSt
v). This excess is dependent on the given bed relative humidity and droplet size. The higher the bed relative humidity, the
higher is the ΔSt
v required to keep the process in the layering regime. Further, it is shown that using bed relative humidity and droplet size
alone is not enough to obtain constant coating quality. The changes in bed relative humidity and droplet size have been identified
to correlate to the fractional area of particles sprayed per unit of time. This parameter can effectively serve as an additional
parameter to be considered for a better control on the coating quality. High coating quality is shown to be achieved by performing
the process close to saturation and spraying droplets small enough to obtain high spraying rate, but not too small to cause
incomplete coverage of the core particles. 相似文献
2.
Polystoma claudecombesi is described as a new species of the Polystomatidae (Monogenea) parasitic in the urinary bladder of the anuran host Rana angolensis. This parasite was collected at three localities in South Africa, namely Vernon Crookes Nature Reserve in Natal province,
Witsieshoek Mountain Resort in the north-eastern Orange Free State and Bovenste Oog in the province of Transvaal. It is the
largest African polystome described to date. Prevalence at Vernon Crookes Nature Reserve was 4.0% and 2.7% in two successive
years, with a mean intensity of 1.0 (n=25 and 36, respectively). One of the two R. angolensis from Witsieshoek was infected with 5 parasites. The diversity and distribution of southern African polystomes is also discussed. 相似文献
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Benjamin D. Jaffe Christelle Gudot Michael Ketterer Moh Leng Kok‐Yokomi Gary L. Leibee 《Ecological Entomology》2019,44(4):480-487
1. The consumption of arsenic is toxic to most biota. However, a noctuid caterpillar was recently reported feeding on a plant known to hyperaccumulate arsenic. 2. The aim of this study was to investigate the effects of arsenic‐rich Pteris vittata L. consumption by Callopistria floridensis G., and measure differences in arsenic concentrations at various stages of development (larval and adult), and associated with exuviae and frass. 3. Callopistria floridensis accumulated extraordinary concentrations of arsenic. The relative accumulation of arsenic was highest in exuviae and larvae. Larvae invariably preferred P. vittata grown on low arsenic soil to P. vittata grown on higher soil arsenic concentrations, and appeared able to selectively forage on lower arsenic concentrations within each treatment. 4. These findings show that C. floridensis is tolerant of arsenic, and successfully develops to adulthood containing elevated concentrations of arsenic. Callopistria floridensis represents the only known terrestrial animal capable of accumulating arsenic, and may have developed novel physiological and behavioural adaptations to regulate the negative effects of arsenic. 相似文献
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Heterologous gene expression in Lactococcus lactis subsp. lactis: synthesis, secretion, and processing of the Bacillus subtilis neutral protease 总被引:1,自引:0,他引:1
M van de Guchte J Kodde J M van der Vossen J Kok G Venema 《Applied and environmental microbiology》1990,56(9):2606-2611
The Bacillus subtilis nprE gene lacking its own promoter sequence was inserted in the lactococcal expression vector pMG36e. Upon introduction of the recombinant plasmid into Lactococcus lactis subsp. lactis strain MG1363, neutral protease activity could be visualized by the appearance of large clearing zones around colonies grown on milk agar plates. By measuring the activities of the neutral protease and the intracellular enzyme lactate dehydrogenase in culture supernatants and cell fractions, it was demonstrated that the neutral protease was actively secreted into the growth medium. This was corroborated by using the Western blot (immunoblot) technique, which showed the presence of the mature form of the neutral protease in the culture supernatant. On the basis of these results, it is concluded that the B. subtilis neutral protease gene was expressed in L. lactis and that the gene product was secreted into the growth medium and was apparently correctly processed to produced a biologically active protein. The secretion of this particular enzyme may be helpful in achieving accelerated cheese ripening. 相似文献
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