1.Introduction,West Nile virus(WNV)is an important arbovirus that affects both animals and humans.It is a flavivirus member of the Flaviviridae family and is primarily spread by Culex mosquitoes.The main enzootic cycl...1.Introduction,West Nile virus(WNV)is an important arbovirus that affects both animals and humans.It is a flavivirus member of the Flaviviridae family and is primarily spread by Culex mosquitoes.The main enzootic cycle of WNV occurs between birds and mosquitoes,with horses and humans serving as dead-end hosts.Although most human infections are inapparent,the virus can cause flu-like malaise(20%)and severe neuroinvasive disorders(<1%),and there is no specific treatment or approved human vaccines.展开更多
The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and tradit...The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and traditional dairy cattle herds were collected and analyzed for the determination of AFM1 using Cobra-cell incorporated high performance liquid chromatography. Of these analyzed samples, 56 (80.0%) tested positive for AFM1 out of which 3 milk samples with high AFM1 concentrations were selectively pooled and subjected to varied conditions of heat treatments and fermentation processes using both indigenized and exotic strains of lactic acid bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus and L. rhamnosus and L. plantarum) as starter cultures respectively. Both processes used either singly or combined, demonstrated high degrees of reducing effects on AFM1 levels. Sterilization of the milk at 121?C and 80?C under the same condition of time (15 - 20) min showed significant reduction of up to 58.8% (p 0.05) in the level of AFM1 when compared with the initial mean AFM1 concentration of the untreated fresh milk. The situation was however different around the boiling temperature of 100?C at which point the level of AFM1 reduction was found to be inconsistent. The indigenized combined strains showed some slight margins of AFM1 reduction in the proportions of (20.5, 30.8 and 43.9)% over and above that of the exotic strains (17.4, 30.0 and 41.1)% in 12 h, 48 h and 72 h of fermentation respectively. Generally, fermentation alone showed lower reduction of AFM1 in milk from 24.5% to 43.9% compared with the reducing activities of (35.4 to 58.8)% when heat-treated milk samples were subsequently subjected to varied fermentation conditions.展开更多
In this paper, the refractory properties of clay from Ozanagogo had been studied for possible utilization in refractory production. The clay had a specific gravity of 2.57, linear firing shrinkage of 1.01%, 2.14 g/cm3...In this paper, the refractory properties of clay from Ozanagogo had been studied for possible utilization in refractory production. The clay had a specific gravity of 2.57, linear firing shrinkage of 1.01%, 2.14 g/cm3 bulk density and porosity of 20.4%. A cold crushing strength of 17.48 MN/m2 was obtained with modulus of rupture of 8.28 MN/m2. The thermal shock resistance exceeded 30 cycles and the refractoriness was 1750℃. The sample was analysed for its chemical composition, and it was revealed that it contained 38.07% alumina (Al2O3), 46.00% silica (SiO2) and iron impurities (Fe2O3) of 0.78%. The results generally showed that Ozanagogo clay could be used as a refractory material.展开更多
Cognitive Radios (CRs) use dynamic threshold estimation (DTE) techniques to better detect primary user signals under noise uncertainty regimes. However, DTE techniques have rarely been compared before, particularly un...Cognitive Radios (CRs) use dynamic threshold estimation (DTE) techniques to better detect primary user signals under noise uncertainty regimes. However, DTE techniques have rarely been compared before, particularly under the one tier CR network (CRN) model, making it difficult to assess their comparative performance characteristics under this regime. Thus, in this paper, we have investigated the performance of some notable DTE methods under the one-tier CRN model. We used the auction game model in our investigation to compare fairly the spectrum efficiency performance of each technique. Our findings show that DTEs generally perform better than the fixed threshold method particularly under unpredictable noise uncertainty regimes. Our results show further that the channel utilization (CU) rate of the fixed threshold method, popularly used by researchers, plummets by 50.26% for a 1 dB increase in the noise uncertainty level, while the CU rate of the DTE techniques interestingly increased by an average of 4%. Our investigation will enable CR Engineers to better understand the performance characteristics of DTE techniques under the one-tier CRN model.展开更多
文摘1.Introduction,West Nile virus(WNV)is an important arbovirus that affects both animals and humans.It is a flavivirus member of the Flaviviridae family and is primarily spread by Culex mosquitoes.The main enzootic cycle of WNV occurs between birds and mosquitoes,with horses and humans serving as dead-end hosts.Although most human infections are inapparent,the virus can cause flu-like malaise(20%)and severe neuroinvasive disorders(<1%),and there is no specific treatment or approved human vaccines.
文摘The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and traditional dairy cattle herds were collected and analyzed for the determination of AFM1 using Cobra-cell incorporated high performance liquid chromatography. Of these analyzed samples, 56 (80.0%) tested positive for AFM1 out of which 3 milk samples with high AFM1 concentrations were selectively pooled and subjected to varied conditions of heat treatments and fermentation processes using both indigenized and exotic strains of lactic acid bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus and L. rhamnosus and L. plantarum) as starter cultures respectively. Both processes used either singly or combined, demonstrated high degrees of reducing effects on AFM1 levels. Sterilization of the milk at 121?C and 80?C under the same condition of time (15 - 20) min showed significant reduction of up to 58.8% (p 0.05) in the level of AFM1 when compared with the initial mean AFM1 concentration of the untreated fresh milk. The situation was however different around the boiling temperature of 100?C at which point the level of AFM1 reduction was found to be inconsistent. The indigenized combined strains showed some slight margins of AFM1 reduction in the proportions of (20.5, 30.8 and 43.9)% over and above that of the exotic strains (17.4, 30.0 and 41.1)% in 12 h, 48 h and 72 h of fermentation respectively. Generally, fermentation alone showed lower reduction of AFM1 in milk from 24.5% to 43.9% compared with the reducing activities of (35.4 to 58.8)% when heat-treated milk samples were subsequently subjected to varied fermentation conditions.
文摘In this paper, the refractory properties of clay from Ozanagogo had been studied for possible utilization in refractory production. The clay had a specific gravity of 2.57, linear firing shrinkage of 1.01%, 2.14 g/cm3 bulk density and porosity of 20.4%. A cold crushing strength of 17.48 MN/m2 was obtained with modulus of rupture of 8.28 MN/m2. The thermal shock resistance exceeded 30 cycles and the refractoriness was 1750℃. The sample was analysed for its chemical composition, and it was revealed that it contained 38.07% alumina (Al2O3), 46.00% silica (SiO2) and iron impurities (Fe2O3) of 0.78%. The results generally showed that Ozanagogo clay could be used as a refractory material.
文摘Cognitive Radios (CRs) use dynamic threshold estimation (DTE) techniques to better detect primary user signals under noise uncertainty regimes. However, DTE techniques have rarely been compared before, particularly under the one tier CR network (CRN) model, making it difficult to assess their comparative performance characteristics under this regime. Thus, in this paper, we have investigated the performance of some notable DTE methods under the one-tier CRN model. We used the auction game model in our investigation to compare fairly the spectrum efficiency performance of each technique. Our findings show that DTEs generally perform better than the fixed threshold method particularly under unpredictable noise uncertainty regimes. Our results show further that the channel utilization (CU) rate of the fixed threshold method, popularly used by researchers, plummets by 50.26% for a 1 dB increase in the noise uncertainty level, while the CU rate of the DTE techniques interestingly increased by an average of 4%. Our investigation will enable CR Engineers to better understand the performance characteristics of DTE techniques under the one-tier CRN model.
