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1.
A simple model for complex dynamical transitions in epidemics 总被引：2，自引：0，他引：2
Dramatic changes in patterns of epidemics have been observed throughout this century. For childhood infectious diseases such as measles, the major transitions are between regular cycles and irregular, possibly chaotic epidemics, and from regionally synchronized oscillations to complex, spatially incoherent epidemics. A simple model can explain both kinds of transitions as the consequences of changes in birth and vaccination rates. Measles is a natural ecological system that exhibits different dynamical transitions at different times and places, yet all of these transitions can be predicted as bifurcations of a single nonlinear model. 相似文献
2.
In this study, a new type of Aliquat 336/PVC membrane has been made for extraction experiments. This new membrane is capable
of holding more Aliquat 336 than previously developed extraction membranes, hence overcoming a major problem that has confronted
many researchers for a long time. The new membrane has been used to investigate the rate of extraction for the Cd(II) ion
in 2.0 M HCl solution and the effect of membrane thickness on the rate of extraction. The experimental results have shown
this new membrane has a promising future in relevant industrial applications. A new method is also used in this study to qualitatively
identify the oily substance on the surface of membrane after the extraction experiment was completed. This oily substance
has been found to be Aliquat 336. 相似文献
3.
Maryam Jorjani Mostafa Sharif Rohani Amin Mirhashemi Rostami Harry Ako Aileen Tan Shau Hwai 《Journal of the World Aquaculture Society》2019,50(4):789-799
The present study aimed to determine the effects of different levels of marigold, Calendula officinalis, powder, 0 (control), 0.5% (M0.5), 1.5% (M1.5), and 2.5% (M2.5), on pigmentation and growth performance of the blue gourami after a 70‐day trial. At the end of the experiment, no significant differences (p > 0.05) were found in fish growth performance and body compositions. Color parameters (L*, a*, and b*) were weekly evaluated by examining a point posterior to the fish operculum. The marigold‐fed fish were darker than the control fish at Weeks 9 and 10. Yellowness intensity of the M2.5 was significantly higher than the other treatments at Week 9. Skin and caudal fin total carotenoids, astaxanthin, canthaxanthin, and β‐carotene contents of the treatment M2.5 were significantly different (p < 0.05) compared to the other treatments. Muscle total carotenoids, astaxanthin, and canthaxanthin contents of the marigold‐treated fish were significantly (p < 0.05) higher than the control group. Muscle β‐carotene contents of the treatments M1.5 and M2.5 were significantly (p < 0.05) higher than the control group. This study shows that marigold powder may be considered an efficient natural carotenoid source for pigmentation in blue gourami. 相似文献
4.
The nutritional effect of Isochrysis galbana and Chaetoceros muelleri cultured with different seaweed extracts on the larval development,growth and survival of the marine shrimp,Penaeus indicus 
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下载免费PDF全文 Kiuomars Rohani‐Ghadikolaei Eisa Abdolalian Fouroghi Hojatollah Gharibnia Masoud Wing‐Keong Ng 《Aquaculture Research》2015,46(6):1444-1454
The microalgae Isochrysis galbana and Chaetoceros muelleri were cultured with seaweed extract (SWE) from six different seaweeds and each SWE was used either as a supplement or as an alternative media to conventional f/2 medium. Microalgae cultured with only the f/2 media acted as the control treatment. I. galbana and C. muelleri were then fed to Penaeus indicus larvae, either singly or in combination, for 8 days to evaluate its nutritional quality. Shrimp larvae fed on microalgae cultured in f/2 media supplemented with SWE from Ulva lactuca or Enteromorpha intestinalis moulted faster (P < 0.05) to the second mysis stage compared with the control. Survival, total length and growth rates were better in shrimp larvae fed on microalgae previously cultured in media supplemented with SWE. In general, shrimp larvae fed microalgae cultured entirely in SWE performed equally well compared with the control. Shrimp larvae fed on mixed microalgae (I. galbana + C. muelleri) showed significantly better growth, survival and development compared with larvae on either single microalgal diet. It was concluded that microalgae cultured with SWE could be used as a low‐cost alternative media in producing live food for the hatchery production of shrimp larvae. 相似文献
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6.
Mujtaba Yegany Gary Butcher Amir Nilipour Richard D.Miles Rohani Karegar 唐文渊 《国外畜牧学(猪与禽)》2002,(6):53-55
每年，仅仅肉鸡就合消耗一亿吨以上的成品饲料。饲料产品中一小部分受到污染就会使养鸡者和消费者付出高昂的代价。污染的饲料是不卫生的，不适合用于饲喂畜禽，因为这样的饲料合危害育禽的生产性能参数，比如健康、体重、饲料转化率、死亡率以及蛋鸡和种鸡的产蛋率。 相似文献
7.
This work presents a series of experimental tests on new practical approaches in membrane design to improve extraction capacity
and rate. We chose an extraction system involving Aliquat 336 as the extractant and Cd(II) as the metal ion to be extracted
to demonstrate these new approaches. The core element in the new membrane assembly was the extractant loaded sintered glass
filter. This membrane assembly provided a large interface area between the extractant and the aqueous solution containing
metal ions. By recycling the aqueous solution through the membrane assembly, the extraction rate was significantly improved.
The membrane assembly also offered good extraction capacity. 相似文献
8.
Kiuomars Rohani‐Ghadikolaei Wing‐Keong Ng Eesa Abdulalian Aghajari Naser Aftabsavar Yusuf 《Aquaculture Research》2012,43(10):1487-1498
Aqueous extracts of green [Ulva lactuca Linnaeus and Enteromorpha intestinalis (Linnaeus) Nees] and red [Gracilaria corticata (J. Agardh) J. Agardh] seaweeds from the Persian Gulf of Iran were examined for their potential usefulness as components of microalga Isochrysis galbana culture medium against conventional f/2 medium. Isochrysis galbana was successfully cultured using the tested seaweed extracts (SWE) and exhibited higher or similar cell density and biomass when SWE were used as a supplement or an alternative medium respectively. When the SWE were used as an alternative medium, microalgal protein, lipid and ash content were similar but carbohydrate increased compared with control. Total saturated fatty acids decreased with a corresponding increase in total mono‐ and polyunsaturated fatty acids following supplementation of f/2 medium with SWE. Eicosapentaenoic acid (EPA) was not affected by SWE treatments but docosahexaenoic acid (DHA) tended to decrease, except for I. galbana cultured with U. lactuca extract. With the exception of potassium, SWE did not significantly impact the mineral content of cultured I. galbana. The study points to the potential usefulness of specific SWE in the production of microalgae as a food source in aquaculture. 相似文献
9.
Pediococcus spp. were isolated from poultry rectum, faeces and food as good probiotic candidates in order to select strains to be used as probiotic in poultry feed.
A total of 168 lactic acid bacteria were isolated and 51 isolates including 31 Lactobacillus spp. and 20 Pediococcus spp. were able to survive in low pH and bile salt concentration. The Pediococcus spp. were identified and their ability to form biofilm, adhesion to Caco-2 cells and antimicrobial activities against enteric pathogenic bacteria were determined.
The results showed the presence of two strains, Pediococcus acidilactici P17 and P19 in rectal swab samples from 21-d old chickens with significant antibacterial activities against Salmonella enteritidis and Escherichia coli.
The results suggest that only a few isolates of Pediococcus with potential probiotic activities are present in the poultry industry.