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排序方式: 共有390条查询结果,搜索用时 15 毫秒
31.
A lab-scale novel biofilm reactor system, Ultra-Compact Biofilm Reactor (UCBR), was studied to investigate its performance and operational characteristics for domestic sewage treatment. The reactor was operated at four different hydraulic retention times, namely, 90, 60, 30 and 15 min. The operating ranges of volumetric loading rates in terms of COD, BOD5, NH+ 4-N and TKN were 5.6-62.1 kg COD/m3 d, 2.6-32.5 BOD5/m3 d, 0.6-3.2 kg NH+ 4-N/m3 d and 0.82-6.2 kg TKN/m3 d, respectively. The COD, BOD5 and NH+ 4-N removal efficiencies at 90-min hydraulic retention time (HRT) and 60-min HRT could exceed 80%, 90% and 99%, respectively. The corresponding maximum biomass concentrations were 12.0 g/L and 15.0 g/L at 90-min HRT and 60-min HRT, respectively. At 30-min HRT, the biomass concentration increased to a maximum of 24.0 g/L. However, COD and BOD5 removal efficiencies decreased to 75% and 80%, respectively, while the NH+ 4-N nitrification efficiency decreased to only 25% to 30%. These observations suggested that high biomass concentration alone was not sufficient to provide a high removal capacity in a UCBR. Further reduction in HRT to 15 min led to an excessive biomass decline from 22.5 g/L to 4.0 g/L. On the whole, the UCBR was able to sustain COD removal and NH+ 4-N conversion of up to 5.96-18.70 kg COD/m3 d and 0.73-1.00 kg NH+ 4-N/m3 d, respectively. 相似文献
32.
Liming Cai Induck Choi Choon‐Ki Lee Kwang‐Keun Park Byung‐Kee Baik 《Cereal Chemistry》2014,91(4):398-405
Variations in physical and compositional bran characteristics among different sources and classes of wheat and their association with bread‐baking quality of whole grain wheat flour (WWF) were investigated with bran obtained from Quadrumat milling of 12 U.S. wheat varieties and Bühler milling of six Korean wheat varieties. Bran was characterized for composition including protein, fat, ash, dietary fiber, phenolics, and phytate. U.S. soft and club wheat brans were lower in insoluble dietary fiber (IDF) and phytate content (40.7–44.7% and 10.3–17.1 mg of phytate/g of bran, respectively) compared with U.S. hard wheat bran (46.0–51.3% and 16.5–22.2 mg of phytate/g of bran, respectively). Bran of various wheat varieties was blended with a hard red spring wheat flour at a ratio of 1:4 to prepare WWFs for determination of dough properties and bread‐baking quality. WWFs with U.S. hard wheat bran generally exhibited higher dough water absorption and longer dough mixing time, and they produced smaller loaf volume of bread than WWFs of U.S. soft and club wheat bran. WWFs of two U.S. hard wheat varieties (ID3735 and Scarlet) produced much smaller loaves of bread (<573 mL) than those of other U.S. hard wheat varieties (>625 mL). IDF content, phytate content, and water retention capacity of bran exhibited significant relationships with loaf volume of WWF bread, whereas no relationship was observed between protein content of bran and loaf volume of bread. It appears that U.S. soft and club wheat bran, probably owing to relatively low IDF and phytate contents, has smaller negative effects on mixing properties of WWF dough and loaf volume of bread than U.S. hard wheat bran. 相似文献
33.
F Ardón A Döhring X Le Thi KF Weitze D Waberski 《Reproduction in domestic animals》2003,38(2):161-165
The goal of this study was to determine the ability of the Hanover gilt model to assess in vivo fertilizing capacity of preserved sperm and to consider whether any modifications to this model were needed. This model evaluates the fertilizing capacity of semen based on the fertilization rate, the rate of normal embryos and the accessory sperm count of 3–5‐day embryos. Its distinguishing characteristics are the use of one‐time insemination of sperm in reduced numbers, of spontaneously ovulating gilts and of ovulation detection through ultrasound examination of ovaries. Reduced sperm numbers allow for an accurate evaluation of the fertilizing potential of different semen treatments, thereby avoiding the compensatory effect of doses calibrated to maximize fertility. The model's usefulness was assessed in a trial run designed to compare the fertilizing capacity of liquid boar semen diluted into two different extenders. The diluent, the boar and the backflow, had no significant effect on any of the parameters studied. Gilts inseminated less than 24 h before ovulation had a significantly higher (p < 0.01) fertilization rate and accessory sperm cell count (p < 0.05) than those inseminated more than 24 h before ovulation. Very good/good embryos from homogeneous litters (only very good/good embryos were present) had a significantly higher (p < 0.01) accessory sperm count than those from heterogeneous litters (at least one embryo was of a different quality and/or oocytes were present). Both very good/good and degenerated/retarded embryos from heterogeneous litters had low accessory sperm numbers. This suggests that accessory sperm count is significantly related to the quality of the litter, but not to the quality of the embryo within gilts. It can be concluded that the Hanover gilt model is sensitive enough to show fertility differences (in this study, those associated with in vivo ageing of semen), while using relatively few gilts and little time. 相似文献
34.
T.L.W. Rothwell N. Anderson K.C. Bremner K.M. Dash L.F. Le Jambre G.C. Merritt B.K.Y. Ng 《Veterinary parasitology》1976,1(3):221-230
Sera from hosts infected with a variety of nematodes were examined for the presence of antibodies against nematode acetylcholinesterase (AChE). Antibodies were detected in the serum from hosts infected with Oesophagostomum spp., Ostertagia spp. and Trichostrongylus spp., but not in serum from hosts infected with Cooperia pectinata or Haemonchus spp., Toxocara spp. or Trichuris vulpis. In those infections in which anti-AChE antibodies were found, some individual animals failed to produce detectable antibodies. The enzyme appeared to possess antigenic specificity at the genus but not the species level. 相似文献
35.
Postslaughter processing of sow carcasses results in the ovaries being exposed to temperatures of 41.3 to 42.1 degrees C within a 30-min time frame. This study investigated whether the maturational and developmental competence of the recovered germinal vesicle stage oocytes could be compromised by post-slaughter processing. The results showed that the in vitro maturation rates of GV stage oocytes exposed to elevated temperature did not significantly differ from the corresponding controls (74.1 vs. 75.8%). Immunocytochemical staining revealed that elevated temperature did not adversely affect metaphase II spindle formation but resulted in extensive disruption of oocyte cytoskeletal organization. This, in turn, had a detrimental effect on parthenogenetic development compared with the corresponding nonheat-treated controls (cleavage rate = 27.7 vs. 65.3%, P < 0.01; blastulation rate = 6.7 vs. 20.6%, P < 0.01). Hence, transient exposure to elevated temperature during slaughter did not have any detrimental effects on nuclear maturation per se, but it did result in extensive cytoskeletal damage, which in turn drastically decreased the developmental competence. 相似文献
36.
Booker CW Schunicht OC Guichon PT Jim GK Wildman BK Pittman TJ Perrett T 《Veterinary therapeutics : research in applied veterinary medicine》2006,7(3):257-274
The relative effect of metaphylactic ceftiofur crystalline free acid (CCFA) versus metaphylactic tilmicosin was evaluated in beef calves under commercial feedlot conditions in Nebraska. At feedlot arrival, 11,605 animals at ultrahigh risk of developing bovine respiratory disease (BRD) were allocated to one of three experimental groups: CCFA-3 (6.6 mg/kg SC), CCFA-7 (6.6 mg/kg), or TILM-3 (tilmicosin, 10 mg/kg SC). Animals were eligible for subsequent BRD treatment 3 (CCFA-3 and TILM-3 groups) or 7 (CCFA-7 group) days later. Compared with the TILM-3 group, overall chronicity, overall mortality, BRD mortality, and metabolic mortality rates were significantly (P < .05) lower in the CCFA-3 and CCFA-7 groups; average daily gain was significantly (P < .05) higher in the CCFA-3 group; the proportion of quality grade No Roll carcasses was significantly (P < .05) lower in the CCFA-3 and CCFA-7 groups; and there were per-animal advantages of 22.05 dollars and 18.98 dollars in the CCFA-3 and CCFA-7 groups, respectively. In beef calves at ultrahigh risk of developing BRD, it is more cost effective to administer metaphylactic CCFA than tilmicosin at feedlot arrival. 相似文献
37.
Small differences between the lattice energies of different zeolites suggest that kinetic factors are of major importance in controlling zeolite nucleation. Thus, it is critical to control the nucleation kinetics in order to obtain a desired microporous material. Here, we demonstrate how careful investigation of the very early stages of zeolite crystallization in colloidal systems can provide access to important nanoscale zeolite phases while avoiding the use of expensive organic templates. We report the effective synthesis of ultrasmall (6- to 15-nanometer) crystals of the large-pore zeolite EMT from template-free colloidal precursors at low temperature (30°C) and very high yield. 相似文献
38.
Risk factors associated with occurrence of nematodes in free range pigs in Busia District,Kenya 总被引:1,自引:1,他引:0
Kagira JM Kanyari PN Githigia SM Maingi N Ng'ang'a JC Gachohi JM 《Tropical animal health and production》2012,44(3):657-664
Nematode infections are a serious constraint to pig production, especially where free range pig keeping is practiced. This
study investigated the epidemiology of nematodes in free range pigs in Busia District, Kenya. Three hundred and six pigs from
135 farms were sampled for faeces that were analysed for nematode eggs per gram (EPG) of faeces using the McMaster technique.
The nematode eggs were also identified to genus and species based on morphology. A questionnaire on risk factors was also
administered to the pig owners. The overall prevalence and mean nematode EPG were 84.2% and 2,355, respectively. The nematode
eggs were identified as those belonging to Oesophagostomum spp. (75%), Strongyloides ransomi (37%), Ascaris suum (18%), Metastrongylus spp. (11%), Trichuris suis (7%) and Physocephalus sexalatus (3%). The prevalence of nematodes was positively correlated (p < 0.05) with the amount of rainfall in the division of the pigs' origin (all nematodes except S. ransomi). The prevalence of nematodes was also associated with the age of the pigs. A lower burden of nematodes was associated (p < 0.05) with a history of deworming (A. suum) and the provision of night housing (S. ransomi and Metastrongylus spp.). In conclusion, this study has provided information on nematode infections and the associated risk factors for free
range pigs in Busia District, which can be used when implementing integrated control measures. 相似文献
39.
Muhid A Robertson I Ng J Yang R Ryan U 《Veterinary journal (London, England : 1997)》2012,191(1):135-137
Two hundred and forty calf faecal samples from 16 Malaysian farms were screened by PCR for Giardia spp. The overall prevalence was 12.5% and the overall farm prevalence was 68.8% (11/16 farms). The prevalence in pre-weaned and weaned calves was 16.7% and 8.3%, respectively. Sequence analysis of 25 isolates identified all as G. duodenalis assemblage E. Management factors associated with an increased risk of infection with Giardia spp. included keeping weaned calves in pens with sand floors and calf age. Keeping pre-weaned calves in pens with concrete floors and calving in single cow calving areas decreased the risk. 相似文献
40.
Chua Lee Kee Lim Chooi Ling Ling Anna Pick Kiong Chye Soi Moi Koh Rhun Yian 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(1):18-27
Plant Foods for Human Nutrition - Cancer is a preventable and treatable disease, however, the incidence rates are on the rise. Classical treatment modalities for cancer include surgery,... 相似文献