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101.
Halyomorpha halys (Stål) is a highly polyphagous plant pest native to eastern Asia. Since its accidental introduction to the USA in the mid-1990s, it has spread across North America and caused serious economic damages. Chemical control has been a widely applied management strategy which is not sustainable on a long-term basis. A nine-year survey using sentinel and naturally laid H. halys was conducted to investigate the extent of natural biological control by parasitoids in managed and non-managed landscapes in northern Delaware, USA. Naturally laid egg masses of native pentatomids were collected to compare the resident parasitoid complex to the one attacking H. halys eggs. Mean parasitism rates of sentinel eggs were below 6% in any given year of the survey with a grand mean of 1.79%. Parasitism of naturally laid H. halys eggs was higher than that of sentinel eggs, but there was no significant difference in parasitism between years and the grand mean was 4.31%. Parasitoid species richness on sentinel and naturally laid H. halys eggs was similar but both were lower than the richness on native pentatomid eggs. H. halys eggs were parasitized by eight species in the genera Anastatus, Trissolcus, Telenomus, and Ooencyrtus. The level of parasitism by native egg parasitoids is insufficient to provide long-term control of H. halys. Trissolcus japonicus (Ashmead), an Asian egg parasitoid that has been recovered in the USA in several locations since 2014, may be the most promising candidate for long-term biological control of H. halys. 相似文献
102.
This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and
modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data
were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot
size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data
were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam
using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section
method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point
bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties
of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture
and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this
study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable
stress design and limit state design. 相似文献
103.
Kwangho Choi Chung Il Lee Kwangseok Hwang Sang-Woo Kim Jong-Hwa Park Yeong Gong 《Fisheries Research》2008,91(2-3):281-290
Data on squid catches of Korean and Japan, water temperatures at depth of 100 m, and night-visible images of fishing boats collected in the East (Japan) Sea from 1970 to 1999 were analyzed to examine the distribution and migration of the Japanese common squid, Todarodes pacificus, in the southwestern part of the East (Japan) Sea. The main fishing grounds detected from squid catch in each grid (0.5° latitude × 0.5° longitude) by Korean squid fishery and night-visible images provided by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) were situated in the southwestern part of the East (Japan) Sea. The distribution and migration route was illustrated from squid catch in each grid and DMSP OLS image. In years of high catches, the fishing grounds were situated mainly between Ulleung Island and the eastern coastal waters of Korea, while in years of low catches they were situated between Ulleung Island and the Yamato Bank in the central East (Japan) Sea. The center of fishing activity began moving northward from around the Korea/Tsushima strait to the northern boundary of the Tsushima Warm Current in March, reaching into the Yamato Bank in September, and then returning to the strait by February. The northward and southward migration routes differed; the northward migration route occurred closer to the mainland coast of Korea than the southward migration route did. This work suggests T. pacificus begin their northward migration almost 2 months earlier than previously suggested. 相似文献
104.
This study was carried out to investigate the influences of feeding frequency of extruded pellet and moist pellet on growth
and body composition of juvenile flounder (initial mean weight 6.3 g) in sub optimal water temperatures. A 2 (diets: extruded
pellet and moist pellet)×2 (feeding frequencies: two and three times daily)×2 (water temperatures: 12 and 17°C) factorial
design with three replications was used. After 60 days of feeding, the feeding frequency did not significantly affect growth
performance of fish. Weight gain, daily feed intake, feed efficiency and protein efficiency ratio were significantly (P<0.05) higher for fish reared at the higher water temperature. At the same water temperature, weight gain, feed efficiency,
and protein efficiency ratio were significantly (P<0.05) higher for fish fed the extruded pellet than moist pellet. The results of this study indicate that feeding frequency
of two times daily is sufficient for optimal growth of juvenile flounder when reared in suboptimal water temperatures, and
an increase in water temperature from 12 to 17°C improved growth and feed efficiency. 相似文献
105.
ABSTRACT: As part of this study on the isolation of cholinesterase inhibitors from natural marine products, the bioactivity of the ethanolic extracts from 27 Korean seaweeds were screened using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory assays. Ecklonia stolonifera exhibited promising inhibitory properties against both AChE and BChE. Bioassay-guided fractionation of the active n -hexane and ethyl acetate (EtOAc) soluble fractions, obtained from the ethanolic extract of E. stolonifera , resulted in the isolation of the sterols; fucosterol ( 1 ) and 24-hydroperoxy 24-vinylcholesterol ( 2 ), from the n -hexane fraction and the phlorotannins; phloroglucinol ( 3 ), eckstolonol ( 4 ), eckol ( 5 ), phlorofucofuroeckol-A ( 6 ), dieckol ( 7 ), triphlorethol-A ( 8 ), 2-phloroeckol ( 9 ) and 7-phloroeckol ( 10 ), from the EtOAc fraction. Of these, compounds 2 , 9 and 10 were isolated from E. stolonifera for the first time. Compounds 4 – 7 , 9 and 10 exhibited inhibitory potential against AChE, with 50% inhibition concentration (IC50 ) values of 42.66 ± 8.48, 20.56 ± 5.61, 4.89 ± 2.28, 17.11 ± 3.24, 38.13 ± 4.95 and 21.11 ± 4.16 μM, respectively; whereas, compounds 1 , 2 , 4 and 6 were found to be active against BChE, with IC50 values of 421.72 ± 1.43, 176.46 ± 2.51, 230.27 ± 3.52 and 136.71 ± 3.33 μM, respectively. It has been suggested that the inhibition of these enzymes by the sterols and phlorotannins derived from marine brown algae could be a useful approach for the treatment of Alzheimer's disease. 相似文献
106.
Kim Soon-Oh Jeong Jin Young Lee Woo-Chun Yun Seong-Taek Jo Ho Young 《Journal of Soils and Sediments》2021,21(8):2755-2769
Journal of Soils and Sediments - Electrokinetic (EK) soil remediation is significantly affected by the electrode configurations. Therefore, this study was conducted to compare the performance of... 相似文献
107.
Kim N. Irvine Mary F. Perrelli Ratchadawan Ngoen-klan Ian G. Droppo 《Journal of Soils and Sediments》2009,9(4):328-341
Background, aim and scope Street sediment samples were collected at 50 locations in a mixed land use area of Hamilton, Ontario, Canada, and metal levels
were analyzed using a sequential extraction procedure for different particle size classes to provide an estimate of potential
toxicity as well as the potential for treatment through best management practices (BMPs).
Methodology The street sediment samples were dry sieved into four different particle size categories and a sequential extraction procedure
was done on each size category following the methodology proposed by Tessier et al. 1979 using a Hitachi 180-80 Polarized Zeeman Atomic Absorption Spectrophotometer.
Results and discussion Analysis of variance, post hoc least-significant difference tests, and kriging analysis showed that spatially Mn and Fe levels
were associated with a well-defined heavy industrial area that includes large iron- and steel-making operations; Cu and Pb
were associated with both the industrial and high-volume traffic areas, while Zn tended to be more associated with high-volume
traffic areas. The potential bioavailability of the metals, based on the sum of chemical fractions 1 (exchangeable) and 2
(carbonate-bound), decreased in order: Zn > Cd > Mn > Pb > Cu > Fe. Based on aquatic sediment quality guidelines, there is
some concern regarding the potential impact of the street sediment when runoff reaches receiving waters.
Conclusions It is possible that a combination of BMPs, including street sweeping and constructed wetlands, could help to reduce street
sediment impact on environmental quality in the Hamilton region. The data presented here would be important in developing
and optimizing the design of these BMPs. 相似文献
108.
Ana T. Silva Martyn C. Lucas Theodore Castro‐Santos Christos Katopodis Lee J. Baumgartner Jason D. Thiem Kim Aarestrup Paulo S. Pompeu Gordon C. O'Brien Douglas C. Braun Nicholas J. Burnett David Z. Zhu Hans‐Petter Fjeldstad Torbjørn Forseth Nallamuthu Rajaratnam John G. Williams Steven J. Cooke 《Fish and Fisheries》2018,19(2):340-362
Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering‐focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South‐East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post‐passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed. 相似文献
109.
In this study, changes in total factor productivity of 12 Korean offshore fisheries between 1997 and 2009 were estimated through
the Malmquist productivity index, which is a nonparametric method. Also, the cause of such changes in productivity of each
fishery was analyzed more specifically by segmenting into factors for technological progress and technical efficiency. As
a result of this analysis, the total factor productivity change of the entire offshore fisheries was −6.0 %. Changes in the
technical efficiency and technological level factors, respectively, contributed 0.2 and −6.2 % to this rate of decrease in
total factor productivity; that is, inactivity of technological progress led to the decrease in productivity of the offshore
fisheries. In addition, technological progress and technical efficiency were found to differently influence the change in
total factor productivity of each fishery. In order for each fishery to improve productivity, better rational fisheries management
policies by the government and efforts by the fishing industry and individual fishing business units must accompany factors
that promote productivity increase. 相似文献
110.
The charge transport mechanism of a wire can be revealed by how its electrical resistance varies with length. We have measured the resistance and current-voltage characteristics of conjugated molecular wires ranging in length from 1 to 7 nanometers, connected between metal electrodes. We observe the theoretically predicted change in direct-current transport from tunneling to hopping as a function of systematically controlled wire length. We also demonstrate that site-specific disruption of conjugation in the wires greatly increases resistance in the hopping regime but has only a small effect in the tunneling regime. These nanoscale transport measurements elucidate the role of molecular length and bond architecture on molecular conductivity and open opportunities for greater understanding of electrical transport in conjugated polymer films. 相似文献