Fused filament fabrication (FFF) or fused deposition modeling is an additive manufacturing (AM) process commonly used for geometric modeling and rapid prototyping of parts called three-dimensional ...(3-D) printing. Commonly used thermoplastic materials in FFF 3-D printing AM are acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polybutylene terephthalate (PBT). However, these materials exhibit relatively low strength and toughness. Therefore, it is desirable to improve various properties of thermoplastics in 3-D printing AM by employing nanotechnology. The combination of 3-D printing and nanotechnology opens new venues for the manufacture of 3-D engineered materials with optimized properties and multifunctionality (e.g. mechanical, electrical, and thermal properties). Hence, in this work, the multifunctional property improvement effects of graphene oxide (GO) on thermoplastic materials suitable for 3-D printing AM are investigated. Low loading of GO with carboxyl and hydroxyl surface functional groups is incorporated into thermoplastic materials suitable for 3-D printing AM by a special mixing technique. ABS is chosen in this study due to its availability. Graphene nanosheets are employed to improve the properties of the developed nanocomposites by 3-D printing AM. GO is chosen to improve the dispersion of graphene nanosheets into the thermoplastic system to increase their interfacial adhesion. A multifunctional property improvement is observed in the developed nanocomposite with less than 0.1 wt% GO. Employing ASTM standard tests, it was found that at a very small loading of 0.06% by weight, GO could improve the properties of the thermoplastic in terms of strength, strain-to-failure, and toughness, while maintaining the stiffness, rendering the developed nanocomposites suitable for various applications of static and dynamic loading. GOs are now commercially available at low prices. At such low loadings, these graphene-type materials become economically feasible components of nanocomposites.
Effective testing of new sensing technologies requires realistic yet deterministic test ranges. The advancements in customizable, adaptive unmanned surface vessels (USV) have contributed to the ...increasing presence of USVs completing maritime site characterizations of test ranges using commercial off-the-shelf (COTS) sensors such as the Tritech Starfish 990F side-scan sonar. This paper aims to present recommendations for the electromechanical integration of a COTS sonar system onto a capable USV through passive techniques such that underwater objects within the littoral zone of Sand Island, Hawaii, are characterized. Results demonstrated a 49% improvement in the sonar images. Therefore, designers are recommended to fully isolate the sensing system from the USV, physically separate the sonar and USV components, and to establish a baseline performance for the system prior to operation.
The presence of a seasonally variable biogenic habitat (eelgrass,
Zostera marina
) increased the spring–summer variability of associated nekton relative to unvegetated bare tidal flat. This ...spatio-temporal pattern emerged because most eelgrass-associated taxa tracked the decline in eelgrass biomass from summer to spring, but in one case reached greater density in spring when predation intensity was low. Among 21 taxa (26,884 individuals) captured, a strong correlation arose between structure association and summer dominance, and certain functional traits, in particular morphology and on- vs. off-bottom position, were strong predictors of eelgrass association. Structure-associated taxa were slender-bodied and pelagic schooling fishes, while habitat generalists or bare-associated taxa were more consistent seasonally, primarily benthic, and cryptically colored with sand. Estuarine use (transient, reproducing, or estuarine resident) was not a strong predictor of structure association or seasonality. Because an identical sampling design was used in five regions of Washington State, USA, coarse-scale (> 100 km) differentiation in nekton assemblages was identified, representing less of the total variation than across seasons but more than across different habitats. While regional nekton differences were attributable in part to geographic distance and eelgrass morphotypes, the most seasonally variable nekton were at sites with morphotypes adding the least vertical structure but highest density. These results support two mechanisms that increase seasonal variability of taxa using structured habitats, including both bottom-up provision of habitat and resources, and subsequent possibilities for negative interspecific interactions and top-down control.
A novel five year Test and Vaccinate or Remove (TVR) wildlife research intervention project in badgers (Meles meles) commenced in 2014 in a 100km2 area of Northern Ireland. It aimed to increase the ...evidence base around badgers and bovine TB and help create well-informed and evidence-based strategies to address the issue of cattle-to-cattle spread and spread between cattle and badgers. It involved real-time trap-side testing of captured badgers and vaccinating those that tested negative for bTB (BadgerBCG-BCG Danish 1331) and removal of those that tested bTB positive using the Dual-Path Platform VetTB test (DPP) for cervids (Chembio Diagnostic Systems, Medford, NY USA). Four diagnostic tests were utilised within the study interferon gamma release assay (IGRA), culture (clinical samples and post mortem), DPP using both whole blood and DPP using serum. BCG Sofia (SL222) was used in the final two years because of supply issues with BadgerBCG. Objectives for this study were to evaluate the performance of the DPP in field conditions and whether any trend was apparent in infection prevalence over the study period. A Bayesian latent class model of diagnostic test evaluation in the absence of a gold standard was applied to the data. Temporal variation in the sensitivity of DPP and interferon gamma release assay (IGRA) due to the impact of control measures was investigated using logistic regression and individual variability was assessed. Bayesian latent class analysis estimated DPP with serum to have a sensitivity of 0.58 (95% CrI: 0.40-0.76) and specificity of 0.97 (95% CrI: 0.95-0.98). The DPP with whole blood showed a higher sensitivity (0.69 (95% CrI: 0.48-0.88)) but similar specificity (0.98 (95% Crl: 0.96-0.99)). The change from BCG Danish to BCG Sofia significantly impacted on DPP serum test characteristics. In addition, there was weak evidence of increasing sensitivity of IGRA over time and differences in DPP test sensitivity between adults and cubs. An exponential decline model was an appropriate representation of the infection prevalence over the 5 years, with a starting prevalence of 14% (95% CrI: 0.10-0.20), and an annual reduction of 39.1% (95% CrI: 26.5-50.9). The resulting estimate of infection prevalence in year 5 of the study was 1.9% (95% CrI: 0.8-3.8). These results provide field evidence of a statistically significant reduction in badger TB prevalence supporting a TVR approach to badger intervention. They give confidence in the reliability and reproducibility in the DPP Whole Blood as a real time trap-side diagnostic test for badgers, and describe the effect of vaccination and reduced infection prevalence on test characteristics.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have developed a compact instrument called the “COmpact COlor BIofinder”, or CoCoBi, for the standoff detection of biological materials and organics with polyaromatic hydrocarbons (PAHs) using a ...nondestructive approach in a wide area. The CoCoBi system uses a compact solid state, conductively cooled neodymium-doped yttrium aluminum garnet (Nd:YAG) nanosecond pulsed laser capable of simultaneously providing two excitation wavelengths, 355 and 532 nm, and a compact, sensitive-gated color complementary metal–oxide–semiconductor camera detector. The system is compact, portable, and determines the location of biological materials and organics with PAHs in an area 1590 cm2 wide, from a target distance of 3 m through live video using fast fluorescence signals. The CoCoBi system is highly sensitive and capable of detecting a PAH concentration below 1 part per billion from a distance of 1 m. The color images provide the simultaneous detection of various objects in the target area using shades of color and morphological features. We demonstrate that this unique feature successfully detected the biological remains present in a 150-million-year-old fossil buried in a fluorescent clay matrix. The CoCoBi was also successfully field-tested in Hawaiian ocean water during daylight hours for the detection of natural biological materials present in the ocean. The wide-area and video-speed imaging capabilities of CoCoBi for biodetection may be highly useful in future NASA rover–lander life detection missions.
Graphical Abstract
Abstract
In laboratory studies, shellfish larvae often respond negatively to augmented CO2, but no prior tests have related wild bivalve larval performance and carbonate chemistry spatiotemporally. ...The geography of Willapa Bay (Washington, USA) naturally generates two distinct regions of carbonate chemistry where non-native Pacific oysters (Crassostrea gigas) dominate the intertidal fauna and successfully reproduce. On the river-influenced east side, pCO2 is higher and alkalinity lower, which both contribute to reduced aragonite saturation state (Ωaragonite 1.3–1.5) relative to the west side receiving low watershed inputs (Ωaragonite 1.8–1.9). pHsws is also >0.1 lower on the east vs. west sides. Despite this difference in field conditions, no biological signal related to carbonate chemistry was apparent in oyster reproduction based on coupled chemical–biological comparisons over three summers. Instead, survival was equal between the two sides of the bay, and settlement was equal or higher on the low-Ωaragonite, low-pH east side. In a temporal comparison of four larval cohorts, settlement differed by two orders of magnitude and increased with water temperature. These field data on oyster reproduction illustrate that population-level effects may not emerge in higher mean CO2 conditions, with possible decoupling due to local adaptation, spatio-temporal heterogeneity, or higher sensitivity to other axes of environmental variability such as temperature.
Abstract
The “Search for life”, which may be extinct or extant on other planetary bodies is one of the major goals of NASA planetary exploration missions. Finding such evidence of biological residue ...in a vast planetary landscape is an enormous challenge. We have developed a highly sensitive instrument, the “Compact Color Biofinder”, which can locate minute amounts of biological material in a large area at video speed from a standoff distance. Here we demonstrate the efficacy of the Biofinder to detect fossils that still possess strong bio-fluorescence signals from a collection of samples. Fluorescence images taken by the Biofinder instrument show that all
Knightia
spp. fish fossils analysed from the Green River formation (Eocene, 56.0–33.9 Mya) still contain considerable amounts of biological residues. The biofluorescence images support the fact that organic matter has been well preserved in the Green River formation, and thus, not diagenetically replaced (replaced by minerals) over such a significant timescale. We further corroborated results from the Biofinder fluorescence imagery through Raman and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopies, scanning electron microscopy, energy dispersive X-ray spectroscopy (SEM–EDS), and fluorescence lifetime imaging microscopy (FLIM). Our findings confirm once more that biological residues can survive millions of years, and that using biofluorescence imaging effectively detects these trace residues in real time. We anticipate that fluorescence imaging will be critical in future NASA missions to detect organics and the existence of life on other planetary bodies.
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Controlling water content in soil is a recurrent and labor intensive operation on almost any experiment about plant physiology. Here we describe a robotic gantry to measure and ...control soil moisture in pots that is modular, inexpensive, easy to build, accurate, precise, and reliable. Machines can be stacked into industrial shelves, coupled with other control systems to conduct multifactorial experiments, and adjusted to accommodate numerous pots of any size allowing for experiments with limitless specimen capacity in terms of height and specimen count. The system can be assembled in up to seven hours using off the shelf components and simple tools at a total cost of $1,276, in 2019 prices. A screening cycle can be performed as fast as every six minutes reducing variations in water content due to evaporation and thus creating precise control of soil moisture. As a validation of the long-term cyclic reliability of the system, the machine was run non-stop for 4480 loops; the equivalent to running an experiment for six months controlling water content every hour. By facilitating high throughput monitoring of soil moisture in pots, reliably and at low cost, this machine can facilitate the development of large-scale experiments on plant physiology.
Sheet metal bending manufacturing companies require changeable and adaptable process planning systems to shorten the production cycle time and reduce operations costs. This is due to globalisation ...and the rapid change in market demands for sheet metal products. In light of this, this paper proposes a web-based feature extraction and recognition system. The system would ensure automated planning of various processes used by a bending machine to produce varieties of sheet metal products. The algorithms were implemented using C++ to produce the geometric and feature models used to extract, and recognise the bending features in various CAD files acquired from literature. Five (5) CAD files of various sheet metals were utilised to test the functionality of this system. The results from the feature recognition process have proven to be precisely what the user has designed and saved in the model file. Bend radius and bend angle. Finally, the developed system is able to transform a STEP file into a feature model and display the 3D CAD model within the least time. It is a cost-efficient standalone system that provides data storage, allows collaboration and data sharing. can be used anywhere where there is internet access.
Fixed-gear cycling performance during criteriums predominantly involves the aerobic system. Whether pacing is another important factor for performance is unknown. The purpose of the present study was ...to explore pacing and/or positioning strategies of fixed-gear riders during criteriums. Race results of an international fixed-gear criterium were analyzed (20 laps for women and 28 laps for men; laps = 1,270 m). Statistics were conducted on individuals lap time and positioning during the finals. Race pattern in women (
= 35) and men (
= 53) revealed that the faster laps (
< 0.05) were in the middle and at the end of the race and the slower laps (
< 0.05) were at the end of the race (laps 17-18 for women and lap 26 for men). The final ranking was significantly correlated with the mean race position (Kendall's tau = 0.664 and 0.689 for women and men, respectively). A coefficient of variation >50% revealed an important positioning variability. The best riders are mostly amongst the first during the race. However, the others exhibited larger mean position variations during the first half of the race. Our results demonstrated variable pacing strategies during fixed-gear criteriums. Although some riders had economical drafting strategies during the first half of the race, riding placed ahead during the whole race seemed to be an essential performance factor.
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