Search

A practical method for identification of defects that occur occasionally during the production of biaxial oriented polypropylene (BOPP) films is developed. The size and morphology of the defects in the BOPP film were observed with optical microscopy, and micro Fourier transform infrared (Micro-FTIR) and Raman spectroscopies were employed to identify the chemical composition of the defects. Significant amounts of ethylene and propylene units were found in the defects, and characteristic vibrational bands for crystalline PP were observed by both IR and Raman. However, one defect exhibited IR characteristics for ordered PE whereas the other showed amorphous PE structure. These results indicate that the defects are composed of either ethylene-propylene block copolymers with long sequences of both propylene and ethylene that can form ordered structures, or ethylene-propylene segmented copolymers with long propylene sequences that can crystallize and shorter ethylene sequences that are amorphous. Possible sources of these foreign materials and corresponding mitigation measures were discussed.

We have isolated 4 naturally-occurring strains of CPV in mainland China and have identified them as CPV-2, 2a, 2b and 2c genotypes according to their VP2 sequences which also revealed substitutions within their right terminal regions. To determine if these substitutions affected the growth characteristics of the 4 strains, we constructed plasmids based on their genomic sequences minus their right terminal sequences, with the latter replaced by a single right terminal region. Analysis of rescued recombinants showed that the substitutions within their natural right termini had no significant effect on their growth characteristics.

The radioactive pollution owing to the discharge of effluents containing radionuclides brings serious toxicological effects on the ecological environment. In this work, the chitosan (CS) and biomass-resourced porous activated carbons (BC) composite membranes (CS/BC) were used as the electrodes for the electrosorption of U(VI) from aqueous solutions. The capacitive characteristic and electrosorption performance of the composite electrodes was systematically investigated. The CV curves of the CS/BC membrane showed normal dependency of scan-rate and U(VI) concentration, reflecting good removal capacity and kinetic rate for U(VI) electrosorption. The CS: BC mass ratios had significant effects on U(VI) electrosorption performance, and the CS/BC-2 is the best among various CS/BC electrodes owing to its good match of functional groups and mesoporous structure. The CS/BC-2 presented high removal capability of for U(VI) electrosorption (207.6 mg/g at the voltage of 0.9 V and pH 4.0, based on Langmuir model). The electrosorption involves in electrical double-layer formation, ion-exchange, complexation and physisorption. The cyclic electrosorption-desorption results and the XPS characterization further clarified this mechanism. The CS/BC-2 could also selectively adsorbed U(VI) from other co-existed metal ions in electrosorption. The results revealed the potential application of electrosorption process by using CS/BC electrodes in U(VI) solution for the cleanup of environmental pollution.

Pathogenic strains of Aleutian mink disease virus (AMDV) such as Utah-1 do not replicate in cell culture (e.g., Crandell Rees feline kidney cells) while the in vitro-adapted AMDV strain ADV-Gorham (ADV-G) is not pathogenic. Here, we constructed a full-length infectious clone (pADV-G). Alignment of the VP2 gene of ADV-G with that of other AMDV strains revealed many amino acid (a.a.) residues conserved among pathogenic isolates that differed in ADV-G. Four virulence-associated, conserved residues of pADV-G VP2 were studied by site-directed mutagenesis (H92A, Q94S, Y115F, and I116L). Mutation of residue 92 or 94 decreased viral-transcription and viral-infectivity levels, whereas mutation of residue 115 or 116 did not affect viral-infectivity in CRFK cells. These results indicated that VP2 residues 92 and 94, both located on the surface of the viral capsid, are critical for AMDV infectivity in vitro.

Mink enteritis virus (MEV) is one of the most important viral pathogens causing serious disease in mink. Type I interferon (IFN) plays a critical role in antiviral innate immunity and, for successful infection, many viruses have evolved evasive strategies against it. Here, we show that MEV infection does not evoke IFN or interferon-stimulated genes (ISGs) responses in feline kidney (CRFK) cells, and that MEV suppresses IFN production in both poly I:C-stimulated and untreated cells. In CRFK cells pre-exposure to IFN, show that infection with, and replication of, MEV remain unaffected. This inhibition appears to be mediated by the MEV nonstructural protein (NS1) with its ORI-binding domain playing a major role.

Construction and characterization of a full-length infectious clone (pMEV) of mink enteritis virus are described. Feline kidney cells (F81) were transfected with pMEV containing an engineered BamHI site that served as a genetic marker. The rescued virus was indistinguishable from its parental virus. The availability of a MEV infectious clone will facilitate studies of viral replication and pathogenicity and will permit the elucidation of determinants of the host range of the parvovirus.

To improve high-frequency speech intelligibility, an improved frequency compression method for high-frequency hearing-impaired patients was evaluated compared to conventional frequency compression scheme and their own hearing aids. The first step in this method was to decompose speech frame for three groups of parameters of the sinusoidal speech model: amplitudes, frequencies, and phases. Frequencies above a pre-calculated cut-off frequency (CF) were compressed and shifted to a lower frequency range to improve high-frequency intelligibility. Different from general methods, the frequency compression ratio was set according to speech intelligibility percentage in different frequency ranges. To avoid spectral distortions in the sounds, the frequency spectrum was split into six bands according to octaves. In addition, phases of compressed frequencies were randomly set to improve the envelope of the compressed signal. In subjective evaluation for Chinese speech identification, six experienced hearing aid users with a severe to profound sensorineural hearing loss were tested. After 6 weeks of training and testing, results showed the mean speech identification was improved at least 7% points in comparison with conventional frequency compression scheme.

Meteorological records show a rise in temperature and decrease in precipitation in most parts of the farming–pastoral ecotone of Northern China over the last 50 years. During the last quarter of the 20th Century, the agrarian sector went through a series of reforms and changes in government policies on land use that have led to extensive changes in land cover. The objective of this study was to redefine the location and analyze the boundary variations under the effects of climate and land use changes in the farming–pastoral ecotone of Northern China. The results showed that the location of study area has been redefined as both a climatic ecotone from the perspective of suitability of precipitation and temperature for agricultural crops and vegetation growth, and also a land use ecotone based on the impacts of farmland restructuring by government policies on land use. In recent decades, the climatic boundary has moved southeast while the land use boundary has moved northwest, showing opposing directions of change. The extent of boundary changes in the northeast and northern sections are far greater than in the northwestern section of the farming–pastoral ecotone of Northern China.

The tensile properties of short δ-Al 2 O 3 fiber randomly reinforced aluminum alloy composites were characterized. Systems based on three matrix alloys, Al–5.5Zn, Al–5.5Mg and Al–12Si, were prepared to observe and measure the microstructural and mechanical characteristics of squeeze cast short fiber composites, including the orientation and length of short fiber, interfacial bond and micro-hardness of the reinforced matrix. It was found that the orientation and length of the short fibers satisfied the Weibull's and normal distribution, respectively. The micro-hardness values of the reinforced matrix alloys were higher than that of the unreinforced alloys. The interfacial bond differed with the variation of matrix alloy. Based on the microstructural characteristics and in situ tensile observation by scanning electronic microscopy, the fracture mechanisms of the three composite systems were discussed and related to the microstructural characterization. Finally, the tensile strengths of the composites were predicted by the statistical integration average method, based on using the maximum energy criterion for the composite strength. In this way, the prediction accounts for the practical distributions of the fiber orientation and length. The predicted results agree well with the experimental data.