Outbreaks of an avian disease in infectious bronchitis-vaccinated chickens in China have led to the characterization of coronaviral isolates Q1, J2, and T3, which were isolated from proventricular tissues of the affected young layer flocks. Serologic analysis revealed that they could induce high titers of infectious bronchitis virus (IBV) antibodies in inoculated specific-pathogen-free (SPF) chickens in indirect enzyme-linked immunosorbent assay but were not neutralized by antisera specific to the IBV serotype M41 and the Australian T strain. In a pathogenicity experiment, the clinical signs and related gross lesions resembling those of field outbreaks were reproduced in SPF chickens, and viruses were reisolated from the damaged tissues, including trachea, proventriculus, duodenum, and cecal tonsil. Sequence data demonstrated the complete S1 amino acid sequences of these isolates were almost identical despite recovery from geographically different areas in China and had 47.3%-82.3% similarity in comparison with the 47 published S1 sequences. On the basis of genotyping and limited serology, the three isolates, which were responsible for field outbreaks of the disease, might be a new IBV variant.
Seven Newcastle disease (ND) virus (NDV) isolates which were recovered from ND outbreaks in chicken and pigeon flocks in China and Taiwan between 1996 and 2000 were genotypically and pathotypically characterized. By phylogenetic analysis of the fusion protein genes, isolates Ch-A7/96, Ch/98-3, Ch/99, Ch/2000, and TW/2000 were placed into two novel subgenotypes, VIIc and VIId. Isolate Ch/98-1 was grouped into subgenotype VIb, while Ch-W6/96 was proven to be a mixture of isolates Ch-A7/96 and Ch/98-1. These isolates were pathotyped as viscerotropic velogenic for Ch/98-3, Ch/99, Ch/2000, and TW/2000; neurotropic velogenic for Ch-A7/96; and mesogenic for Ch/98-1. Three separate, comparative, genetic analyses of the F genes, including genetic distance measurement, phylogenetic tree analysis, and residue substitution analysis, were performed with our isolates and selected NDV strains from GenBank. Results showed that the close genetic similarity provided evidence for the epidemiological linkage between the outbreaks in China and Taiwan and that the 1990s outbreaks in Asia, the Middle East, Africa, and Europe constituted the fourth panzootic of ND. In combination with epidemiological analysis, an evolutionary model of the NDV strains, representative of the direction of transmission within the NDV strains, was proposed, and epidemiology of NDV transmission was evaluated with emphasis on molecular aspects. Finally, a cross-protective experiment indicated that at least one strain (Ch-A7/96) among our NDV isolates was an antigenic variant, responsible for recent outbreaks of ND in vaccinated chicken flocks.Newcastle disease (ND) is one of the most serious diseases of poultry caused by ND virus (NDV), the only member of the avian paramyxovirus type 1 serotype (3). NDV belongs to the Rubulavirus genus of the family Paramyxoviridae and has a negative-sense, single-stranded-RNA genome that consists of approximately 15 kbp. The genome encodes six major polypeptides in the 5Ј-to-3Ј direction, including RNA-directed RNA polymerase, hemagglutinin-neuraminidase, fusion protein, matrix protein, phosphoprotein, and nucleoprotein (15). The pathogenicity of any newly isolated strain can be assessed by determining the intracerebral pathogenicity index (ICPI) and the mean death time (MDT). By pathotyping, NDV strains were classified into the highly pathogenic (velogenic), intermediate or moderately pathogenic (mesogenic), and lowly pathogenic (lentogenic) categories. Some lentogenic strains of NDV are avirulent, whereas velogenic forms were further classified as viscerotropic velogenic (VV) and neurotropic velogenic (NV) types based on clinical manifestation and lesions (3). The primary molecular determinant for NDV pathogenicity is the amino acids of the F protein cleavage site (10,16,18).Three panzootics of ND have occurred since the disease was first recognized (1, 3). By restriction site mapping and sequence analysis of the F gene, NDV strains were divided into eight genotypes (6, 11, 13). Among these, at least three genotypes (II, I...
On-road heavy-duty diesel vehicles are a major contributor of oxides of nitrogen (NO) emissions. In the US, many heavy-duty diesel vehicles employ selective catalytic reduction (SCR) technology to meet the 2010 emission standard for NO. Typically, SCR needs to be at least 200°C before a significant level of NO reduction is achieved. However, this SCR temperature requirement may not be met under some real-world operating conditions, such as during cold starts, long idling, or low speed/low engine load driving activities. The frequency of vehicle operation with low SCR temperature varies partly by the vehicle's vocational use. In this study, detailed vehicle and engine activity data were collected from 90 heavy-duty vehicles involved in a range of vocations, including line haul, drayage, construction, agricultural, food distribution, beverage distribution, refuse, public work, and utility repair. The data were used to create real-world SCR temperature and engine load profiles and identify the fraction of vehicle operating time that SCR may not be as effective for NO control. It is found that the vehicles participated in this study operate with SCR temperature lower than 200°C for 11-70% of the time depending on their vocation type. This implies that real-world NO control efficiency could deviate from the control efficiency observed during engine certification.
h i g h l i g h t s Natural gas composition impacts the emissions from lean-burn engines. Lower THC, CH 4 , and NO x emissions for stoichiometric vs. lean-burn engines. NH 3 emissions produced important increases for the stoichiometric engines. Lubricant oil combustion was the main source for particle number formation. Higher carbonyl emissions for lean-burn vs. stoichiometric engines.
The reduction of emissions from diesel engines has been one of the primary elements in obtaining improvements in air quality and greenhouse gas reduction goals. Dimethyl carbonate (DMC) is an oxygenate fuel that can be used in petroleum diesel that is been lightly studied, but could provide significant reductions in particulate matter (PM) emissions from internal combustion engines. This study evaluated the emissions impacts of 5%, 12.5%, 20%, and 30% blends of DMC in a California diesel fuel. DMC showed PM reductions increased with increasing DMC blend levels, ranging from 30% to 78% for the DMC5 to DMC30 blends. In contrast, particle number emissions increased with increasing DMC levels, which could be attributed to the enhanced formation of small nucleation particles as the levels of larger accumulation particles were reduced. NO x emissions showed increases of 3.2% and 3.1%, respectively, for the higher 20% and 30% blends, but no statistically significant differences for the 5% and 12.5% blends. Carbon monoxide (CO) emissions showed strong reductions from 26.3% to 60.9% with DMC blending, while total hydrocarbons (THC) emissions showed increases from 32.5% to 137% with DMC. Most of the hydrocarbon species showed increases with increasing DMC blend levels, including benzene and most mono-aromatic hydrocarbons. Similarly, formaldehyde and acetaldehyde showed statistically significant increases with DMC blending relative to diesel fuel. The carbon dioxide (CO 2) emissions and brake specific fuel consumption (BSFC) increased with increasing DMC blend levels compared to diesel fuel.
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