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61.
62.
Justin L. Milner Cristina Bunget Fadi Abu-Farha Thomas Kurfess Vincent H. Hammond 《Journal of Manufacturing Processes》2013,15(2):219-226
Nanostructured materials are a relatively new class of materials that exhibit advanced mechanical properties, thus improving performance and capabilities of products, with potential applications in the automotive, aerospace and defense industries. Among the severe plastic deformation (SPD) methods currently used for achieving nanoscale structures, accumulative roll bonding (ARB) is the most favorable method to produce grain refinement for continuous production of metallic sheets at a bulk scale.In this article, a model that describes the evolution of material strength due to processing via accumulative roll bonding was developed. ARB experiments were conducted on CP-Ti Grade 2 at a selected set of conditions. The results showed significant grain refinement in the microstructure (down to ~120 nm) and a two-fold increase in tensile strength as compared to the as-received material. The developed model was validated using the experimental data, and exhibited a good fit over the entire range of ARB processing cycles. To further validate the model and ensure its robustness for a wider array of materials (beyond CP-Ti), a review of efforts on ARB processing was carried out for five other materials with different initial microstructures, mechanical properties, and even crystalline structures. The model was still able to capture the strengthening trends in all considered materials. 相似文献
63.
Tony Svejcar Chad Boyd Kirk Davies Matthew Madsen Jon Bates Roger Sheley Clayton Marlow David Bohnert Mike Borman Ricardo Mata-Gonzàlez John Buckhouse Tamzen Stringham Barry Perryman Sherman Swanson Kenneth Tate Mel George George Ruyle Bruce Roundy Chris Call Kevin Jensen Karen Launchbaugh Amanda Gearhart Lance Vermeire John Tanaka Justin Derner Gary Frasier Kris Havstad 《Environmental management》2014,53(6):1035-1038
In a previous article, Beschta et al. (Environ Manag 51(2):474–491, 2013) argue that grazing by large ungulates (both native and domestic) should be eliminated or greatly reduced on western public lands to reduce potential climate change impacts. The authors did not present a balanced synthesis of the scientific literature, and their publication is more of an opinion article. Their conclusions do not reflect the complexities associated with herbivore grazing. Because grazing is a complex ecological process, synthesis of the scientific literature can be a challenge. Legacy effects of uncontrolled grazing during the homestead era further complicate analysis of current grazing impacts. Interactions of climate change and grazing will depend on the specific situation. For example, increasing atmospheric CO2 and temperatures may increase accumulation of fine fuels (primarily grasses) and thus increase wildfire risk. Prescribed grazing by livestock is one of the few management tools available for reducing fine fuel accumulation. While there are certainly points on the landscape where herbivore impacts can be identified, there are also vast grazed areas where impacts are minimal. Broad scale reduction of domestic and wild herbivores to help native plant communities cope with climate change will be unnecessary because over the past 20–50 years land managers have actively sought to bring populations of native and domestic herbivores in balance with the potential of vegetation and soils. To cope with a changing climate, land managers will need access to all available vegetation management tools, including grazing. 相似文献
64.
Justin A. Pals Elizabeth D. Wagner Michael J. Plew Menghang Xi Matias S. Attene-Ramos 《环境科学学报(英文版)》2017,29(8):224-230
Haloacetamides(HAMs) are cytotoxic, genotoxic, and mutagenic byproducts of drinking water disinfection. They are soft electrophilic compounds that form covalent bonds with the free thiol/thiolate in cysteine residues through an S_N2 reaction mechanism.Toxicity of the monohalogenated HAMs(iodoacetamide, IAM; bromoacetamide, BAM;or chloroacetamide, CAM) varied depending on the halogen substituent. The aim of this research was to investigate how the halogen atom affects the reactivity and toxicological properties of HAMs, measured as induction of oxidative/electrophilic stress response and genotoxicity. Additionally, we wanted to determine how well in silico estimates of electrophilic softness matched thiol/thiolate reactivity and in vitro toxicological endpoints.Each of the HAMs significantly induced nuclear Rad51 accumulation and ARE signaling activity compared to a negative control. The rank order of effect was IAM BAM CAM for Rad51, and BAM ≈ IAM CAM for ARE. In general, electrophilic softness and in chemico thiol/thiolate reactivity provided a qualitative indicator of toxicity, as the softer electrophiles IAM and BAM were more thiol/thiolate reactive and were more toxic than CAM. 相似文献
65.
The patterns of genetic diversity and connectivity were investigated in Cucumaria frondosa, the most abundant sea cucumber in the North Atlantic, to assist in the management and conservation of this ecologically
important marine invertebrate, which is the target of an emerging fishery. Mitochondrial DNA COI sequences of 334 C. frondosa were obtained and analyzed, mainly from its western North Atlantic range, where the commercial fishery is being developed,
with complementary sampling in the mid- and eastern North Atlantic. Analysis of molecular variance showed no significant (P > 0.05) differences among subpopulations in the western region suggesting that it constitutes one panmictic population. The
same analysis showed low, but significant differences between eastern and western Atlantic populations. Coalescent analyses
using isolation with migration models and a Bayesian skyline plot indicated historical divergence and a general increase in
population size prior to the last glacial maximum and highly asymmetric gene flow (nearly 100 times lower from west to east)
between sea cucumbers from North America and Norway. Results suggest that subpopulations of C. frondosa within the western North Atlantic have been highly connected. We propose that aided by the high-connectivity local subpopulations
can recover rapidly from natural (i.e., ice ages) or anthropogenic (i.e., overfishing) population declines through recruitment
from deep refugia. 相似文献
66.
This Incubator contends that the concept of validity generalization has been overgeneralized in its capacity to predict work performance for three reasons: sampling bias in the occupations selected for analysis, the prediction of acceptable performance to the exclusion of superior performance, and the conflation of statistical prediction and psychological meaning. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
67.
Charles G. Morton Justin L. Huntington Greg M. Pohll Richard G. Allen Kenneth C. McGwire Scott D. Bassett 《Journal of the American Water Resources Association》2013,49(3):549-562
Agricultural irrigation accounts for a large fraction of the total water use in the western United States. The Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) remote sensing energy balance model is being used to estimate historical agricultural water use in western Nevada to evaluate basin‐wide water budgets. Each METRIC evapotranspiration (ET) estimate must be calibrated by a trained user, which requires some iterative time investment and results in variation in ET estimates between users. An automated calibration algorithm for the METRIC model was designed to generate ET estimates comparable to those from trained users by mimicking the manual calibration process. Automated calibration allows for rapid generation of METRIC ET estimates with minimal manual intervention, as well as uncertainty and sensitivity analysis of the model. The variation in ET estimates generated by the automated calibration algorithm was found to be similar to the variation in manual ET estimates. Results indicate that uncertainty was highest for fields with low ET levels and lowest for fields with high ET levels, with a seasonal mean uncertainty of approximately 5% for all fields. In addition, in a blind comparison, automated daily and seasonal ET estimates compared well with flux tower measurement ET data at multiple sites. Automated methods can generate first‐order ET estimates that are similar to time intensive manual efforts with less time investment. 相似文献
68.
69.
Emma R. Wilson Kelly L. Smalling Timothy J. Reilly Elmer Gray Laura Bond Lance Steele Prasanna Kandel Alison Chamberlin Justin Gause Nicole Reynolds Ian Robertson Stephen Novak Kevin Feris Merlin M. White 《Journal of the American Water Resources Association》2014,50(2):420-433
Fungicides are moderately hydrophobic and have been detected in water and sediment, particularly in agricultural watersheds, but typically are not included in routine water quality monitoring efforts. This is despite their widespread use and frequent application to combat fungal pathogens. Although the efficacy of these compounds on fungal pathogens is well documented, little is known about their effects on nontarget fungi. This pilot study, a field survey in southwestern Idaho from April to December 2010 on four streams with varying pesticide inputs (two agricultural and two reference sites), was conducted to assess nontarget impact of fungicides on gut fungi, or trichomycetes. Tissues of larval black flies (Diptera: Simuliidae), hosts of gut fungi, were analyzed for pesticide accumulation. Fungicides were detected in hosts from streams within agricultural watersheds but were not detected in hosts from reference streams. Gut fungi from agricultural sites exhibited decreased percent infestation, density and sporulation within the gut, and black fly tissues had elevated pesticide concentrations. Differences observed between the sites demonstrate a potential effect on this symbiotic system. Future research is needed to parse out the details of the complex biotic and abiotic relationships; however, these preliminary results indicate that impacts to nontarget organisms could have far‐reaching consequences within aquatic ecosystems. 相似文献