This study investigated the effect of long chain fatty acids (LCFAs) removal as a pretreatment prior to anaerobic digestion on the production of methane from food waste. The results showed that the anaerobic digestion of food waste containing 1.6 g COD/L of LCFAs was not inhibited (4 days lag-time, 78.3 % methane recovery in 35 days) compared to that of lipid free food waste (3 days lag time, 72.5 % methane recovery in 35 days); however, some unsaturated LCFAs, which are toxic to microorganism, were accumulated in the batch anaerobic digestion reactor. Meanwhile, in a methanogenic activity study, the activity of methanogens was observed to be linearly inhibited by the presence of more than 1 g COD/L of LCFAs. The possibility of the accumulation of unsaturated LCFAs in the reactor should be considered when operating a large-scale continuous system. 相似文献
Waterborne outbreaks of enteric viruses are a major public health concern. The present study has been carried out to assess the presence of enteric viruses responsible for human acute gastroenteritis (AGE) in groundwater intended for drinking and produce washing. In total, 62 samples from groundwater for drinking and produce washing collected from Dec 2007 to Dec 2008 in Seoul were tested for enteric viruses using conventional RT–PCR, ELISA, and real-time RT–PCR. Our results showed that enteric viruses were detected in 7 (8.8%) groundwater samples. Rotaviruses were detected in 3 (4.8%) of the samples by ELISA; human adenoviruses were detected in 2 (3.2%) of the samples by ELISA; and nested RT–PCR detected noroviruses in 2 (3.2%) of the samples. In one of the groundwater sample, the norovirus RNA was detected by conventional RT–PCR which was confirmed positive by real-time RT–PCR. Additionally, real-time RT–PCR successfully detected norovirus RNA in five out of 62 water samples (8.1%). The data demonstrate that real-time RT–PCR will be useful as a rapid and sensitive method for detecting norovirus in water samples. Phylogenetic analysis revealed that the noroviruses detected in two of the groundwater samples belonged to GII-4. These studies can provide important information for the prevalence of enteric viruses in Korean groundwater. 相似文献
In this study, the effect of moisture supply during desiccation in a landfill liner system under the climatic conditions prevalent
in spring and summer in Korea was investigated. The specimens used in the test were a mixture of dredged clay (parent soil)
combined with additives Pa or Pb (proprietary cementing materials — Pa is mostly silicate powder and Pb is mostly quicklime).
The mixing ratio of the dredged clay to Pa was 5: 1 and that for dredged clay to Pb was 20: 3 (w/w). The effect of moisture
supply to the liner system was evaluated in three ways: the uniaxial compressive strength, permeability, and shrinkage tests
during desiccation. From the results, the compressive strength of the Pa/Pb-clay mixture without moisture supply decreased
more dramatically than that of the Pa/Pb-clay mixture with moisture supply during desiccation. The permeability of the latter
decreased more rapidly than that of the former. Shrinkage of the Pa/Pb-clay mixture with moisture supply during the curing
process was less than that of the Pa/Pb-clay mixture without moisture supply. 相似文献
The continental shelf ecosystem on the Eastern Scotian Shelf (ESS) has experienced drastic changes. Once common top predators are a small fraction of their historical abundance, and much of the current community structure is now dominated by pelagic fishes and invertebrates. Embedded within this food web, Atlantic cod and gray seal populations have recently exhibited nearly opposite trends. Since 1984, cod populations have decreased exponentially at a rate averaging 17% per year, whereas gray seals have continued to increase exponentially at a rate of 12%. We reexamined the impact of gray seals on Atlantic cod dynamics using more than 30 years of data on the population trends of cod and gray seals while incorporating new information on seal diet and seasonal distribution. The closure of the cod fishery over 10 years ago allowed for a better estimation of natural mortality rates. We quantified the impact of seals on ESS cod by (1) estimating trends in seal and cod abundance, (2) estimating the total energy needed for seal growth and maintenance from an energetics model, (3) using estimates of the percentage of cod in the total diet derived from quantitative fatty acid signature analysis (QFASA) and of the size-specific selectivity of cod consumed (derived from otoliths collected from fecal samples), and (4) assuming a gray seal functional response. Uncertainties of the model estimates were calculated using the Hessian approximation of the variance-covariance matrix. Between 1993 and 2000, cod comprised, on average, < 5% of a gray seal's diet. Our model shows that, since the closure of the fishery, gray seals have imposed a significant level of instantaneous mortality (0.21), and along with other unknown sources of natural mortality (0.62), are contributing to the failure of this cod stock to recover. 相似文献
An alternative, and potentially better, means to process prime LED sapphire wafers is proposed. A brief history of material removal mechanisms suggests that brittle materials can be abraded in a ductile regime and that this can be a superior mode of removal. Advantages in material removal rate, surface finish and subsurface damage for a 2-body ductile removal of sapphire are shown relative to 3-body material removal. A major difficulty with this approach may be getting the LED manufacturing industry to understand that the appearance of the sapphire surface is quite different, unfamiliar yet predictable. Finally, some potential alternative process approaches are discussed that utilize 2-body material removal. 相似文献
The cover image is based on the Original Article Noninvasive prenatal paternity testing by means of SNP-based targeted sequencing by Jacqueline Chor Wing Tam et al., https://doi.org/10.1002/pd.5595 .
Large (to >1 m), diurnally active tiger snakes (Notechis scutatus) are abundant on Carnac Island, near the coast of Western Australia. Our behavioural and mark-recapture studies provide the
first ecological data on this population, and reveal a surprising phenomenon. Many adult tiger snakes have had their eyes
destroyed, apparently during nest defence, by silver gulls (Larus novaehollandiae). This loss of vision did not reduce the snakes' body condition (mass relative to length), or their rates of growth or survival
(measured over a 12-month period). Blind male snakes trail-followed females, and mated successfully. Thus, destruction of
a major sensory modality had no detectable effect on these predators. This result is strongly counter-intuitive, but mirrors
an earlier report of congenital blindness (without ill-effects) in American viperid snakes. Similarities between the two systems
(island populations, highly venomous snakes, reliance on sessile prey) clarify the circumstances under which the loss of vision
does not reduce an organism's viability. These natural experiments support Gans' hypothesis of “momentarily excessive construction”
in that the snakes possess a complex organ system that they do not actually require for successful feeding, survival or reproduction.
Received: 30 November 1998 / Received in revised form: 24 April 1999 / Accepted: 9 May 1999 相似文献
The next generation of manufactured products must be sustainable and industrially eco-efficient, making materials derived
from plants an alternative of particular interest. Wheat gluten (WG) is an interesting plant material to be used for production
of plastic similar materials due to its film-forming properties. For usage of plastics in a wider range of applications, composite
materials with improved mechanical properties are demanded. The present study investigates the possibilities of reinforcing
WG plastics with hemp fibers. Samples were manufactured using compression molding (130 °C, 1600 bar, 5 min). Variation in
fiber length, content (5, 10, 15 and 20 wt%) and quality (poor, standard, good) were evaluated. Mechanical properties and
structure of materials were examined using tensile testing, light and scanning electron microscopy. Hemp fiber reinforcement
of gluten plastics significantly influenced the mechanical properties of the material. Short hemp fibers processed in a high
speed grinder were more homogenously spread in the material than long unprocessed fibers. Fiber content in the material showed
a significant positive correlation with tensile strength and Young’s modulus, and a negative correlation with fracture strain
and strain at maximum stress. Quality of the hemp fibers did not play any significant role for tensile strength and strain,
but the Young’s modulus was significantly and positively correlated with hemp fiber quality. Despite the use of short hemp
fibers, the reinforced gluten material still showed uneven mechanical properties within the material, a result from clustering
of the fibers and too poor bonding between fibers and gluten material. Both these problems have to be resolved before reinforcement
of gluten plastics by industrial hemp fibers is applicable on an industrial scale. 相似文献