A risk function based on the standardized mean squared error of prediction is widely used for measuring the goodness of a model. However, using the risk function directly for model selection is generally not possible ...
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A risk function based on the standardized mean squared error of prediction is widely used for measuring the goodness of a model. However, using the risk function directly for model selection is generally not possible due to its inclusion of unknown parameters. The c p criterion is an asymptotic unbiased estimator of the risk function that has been commonly used in place of the risk function for model selection. Because the c p criterion can have a non-negligible bias against the risk function when the sample size is small, a modified c p criterion that completely corrects this bias was proposed by Fujikoshi and Satoh (1997) in a multivariate linear regression model. In this paper, we propose a modified c p criterion for common univariate models that generalize previous studies, i.e., the models in which the predicted response variables are defined as the product of a hat matrix and a vector of response variables.
The impact of the organiccarbon to nitrate ratio (c/N ratio) on mixotrophic denitrification rate has been scarcely studied. Thus, this work aims to investigate the effect of the c/N ratio on the mixotrophic denitrifi...
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The impact of the organiccarbon to nitrate ratio (c/N ratio) on mixotrophic denitrification rate has been scarcely studied. Thus, this work aims to investigate the effect of the c/N ratio on the mixotrophic denitrification when methanol is used as a source of organic matter and elemental sulfur as an electron donor for autotrophic denitrification. For this, two initial concentrations of NO3--N (50 and 25 mg/L) at a stoichiometric ratio of S-0/N, and four initial c/N ratios (0, 0.6, 1.2, and 1.9 mg cH3OH/mg NO3- -N) were used at 25 (+/- 2) degrees c. The results showed that when using a c/N ratio of 0.6, the highest total nitrogen removal was obtained and the accumulation of nitrites was reduced, compared to an autotrophic system. The most significant contribution to nitrate consumption was through autotrophic denitrification (AuDeN) for a c/N ratio of 0.6 and 1.2, while for c/N = 1.9 the most significant contribution of nitrate consumption was through heterotrophic denitrification (HD). Finally, organic supplementation (methanol) served to increase the specific nitrate removal rate at high and low initial concentrations of substrate. Therefore, the best c/N ratio was 0.6 since it allowed for increasing the removal efficiency and the denitrification rate.
In this study, with 2.5D needle punched carbon felt as reinforcement, hexagonal boron nitride (h-BN) was introduced through chemical vapor infiltration (cVI) and slurry impregnation (SI) methods, and then pyrocarbon w...
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In this study, with 2.5D needle punched carbon felt as reinforcement, hexagonal boron nitride (h-BN) was introduced through chemical vapor infiltration (cVI) and slurry impregnation (SI) methods, and then pyrocarbon was deposited through cVI to convert the BN-containing preform into carbon fiber reinforced carbon-boron nitride binary matrix composites (c/c-BN). The microstructure and mechanical properties of c/c-BN(P) composites prepared by SI combined with cVI were compared with those of c/c-BN(cVI) composites prepared by cVI. The tribological behavior of c/c-BN(P) composites containing different contents of h-BN fillers and c/c-BN (cVI) composites with and without heat treatment was investigated by the ball-on-disk technique in dry sliding conditions using Gcr15 steel balls and Si3N4 balls as sliding counterparts at two different sliding speeds (v = 0.2 and 0.8 m/s), and compared with the c/ccomposites used as a reference. c/c-BN(P) composites exhibit improved tribological behavior, which can be explained by the combined effect of SI and cVI on the microstructure and mechanical properties, leading to changes in the wear mechanism of the c/c-BN composites. The excellent reinforcement is attributed to the integrity structure of the c/c-BN(P), which can make the selflubricating friction layer stably exist on the surface of the material and significantly reduce the friction coefficient and wear loss of the c/c-BN(P) composite. Furthermore, the mechanical and tribological properties of c/cBN(P) composites can be adjusted by using different volume content of h-BN. The present work shows that c/cBN(P) composites have wide application prospects as anti-friction and wear-resistant materials.
Ultra-high temperature ceramic-modified c/ccomposites (c/c-UHTcs) were prepared by the reactive infiltration of K2MeF6 (Me = Zr, Ti) mixed with Si and Zr-Si powders. Molten salt infiltration can be divided into two s...
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Ultra-high temperature ceramic-modified c/ccomposites (c/c-UHTcs) were prepared by the reactive infiltration of K2MeF6 (Me = Zr, Ti) mixed with Si and Zr-Si powders. Molten salt infiltration can be divided into two stages: salt ion melt and Me-Si alloy melt. In the temperature range below 1400 degrees c, Zr and Si dissolve in the molten salt, are carried by the ion melt, and precipitate at the Pyc interface to form carbides. Above 1400 degrees c, a large amount of molten salt volatilises and thermally decomposes. The Me-Si alloy forms a melt and infiltrates the c/c matrix, and finally forms c/c-Zrc-Sic, c/c-Ti3Sic2-Sic, and c/c-Zrc-Tic-Siccomposites. The c/c-ZrcSiccomposite with the highest Zrccontent exhibited the lowest mass rate (2.6 +/- 0.02 mg/s) and linear ablation rate (0.82 +/- 0.04 mu m/s), which were reduced by 43.5 and 50.8 %, respectively, compared to the unmodified c/cZrc-Siccomposite.
Rotary ultrasonic milling technology (RUM), as a surface strengthening machining method, was proposed to utilize in processing of c/Siccomposites for enhancing anti-fatigue performance innovatively. Static tensile, i...
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Rotary ultrasonic milling technology (RUM), as a surface strengthening machining method, was proposed to utilize in processing of c/Siccomposites for enhancing anti-fatigue performance innovatively. Static tensile, intermittent fatigue and residual strength test were carried out. Due to constant impingement of high-frequency and low-amplitude vibration, surface residual compressive stress was formed near 2 GPa maximally. Axial thermal residual stress in fiber achieved -662.4 MPa proved by loading-unloading test. The peak value of fatigue damage parameter was reduced significantly. RUM surface restrains most of interface cracks because of residual compressive stress, and hinder the growth of fiber cracks for better machined surface quality. The damage accumulation, the first stress redistribution and fiber reinforcement stage were delayed. Average damage rate was decreased by 80.5 %. Residual tensile strength of RUM c/Sic was improved after fatigue, up to 95.8 % of tensile strength. The strengthening effect from RUM on fatigue property of c/Sic is significant and valuable.
D cryo-plate method was successfully adapted for storage at - 80 degrees c and - 196 degrees c of Allium shoot tips. The optimal D cryo-plate method using garlic shoot tips for the storage at - 80 degrees c and - 196 ...
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D cryo-plate method was successfully adapted for storage at - 80 degrees c and - 196 degrees c of Allium shoot tips. The optimal D cryo-plate method using garlic shoot tips for the storage at - 80 degrees c and - 196 degrees c includes preculture of shoot tips for 2 days at 25 degrees c on solidified 1/2 MS medium containing 0.3 M sucrose, then placing them in wells on an aluminum cryo-plate, embedded in calcium alginate gel. Osmoprotection was performed by immersing the cryo-plates with shoot tips for 30 min at 25 degrees c in 2.0 M glycerol and 1.0 M sucrose. The optimal dehydration time of shoot tips was for 30 to 180 min at 25 degrees c. cooling was performed by transferring the samples on the cryo-plate into 2 ml cryotubes, then cooling into a deep freezer at - 80 degrees c for 14 days or directly plunging into liquid nitrogen (- 196 degrees c) for 60 min. The regrowth rate of shoot tips stored both at - 80 degrees c and - 196 degrees c was almost 100%. This optimized procedure was applied to seven Allium spp. The average regrowth rates after cooling at - 80 degrees c and - 196 degrees c were 95.3 and 94.0%, respectively. Thus, the storage of shoot tips at - 80 degrees c using D cryo-plate method is considered to be efficiently applicable for practical genebank storage. Key message D cryo-plate method was successfully adapted for storage at - 80 degrees c of Allium shoot tips. Grass transition temperature of shoot tips after air desiccation were - 39.4 degrees c.
A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (cFRP) is proposed: cFRPs are first fully carbonized to cF reinforced carbon (c/c) preforms, and then are manufactured into high value...
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A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (cFRP) is proposed: cFRPs are first fully carbonized to cF reinforced carbon (c/c) preforms, and then are manufactured into high value-added c/ccomposites. The results showed that the carbon residue rate of epoxy-resin (EP) matrix was fully recovered as the decomposition route of EP matrix was changed by charring agent. The recycled cF (rcF) was not markedly oxidized or thermally damaged, and possessed comparable properties with those of the virgin cF (vcF) after pyrolysis. The pyrolyticchar had no obvious negative effect on the densification efficiency of the rcF reinforced carbon (rcF/c) composites. Both of the rcF/c and vcF reinforced carbon (vcF/c) composite bodies were quite dense, and exhibited almost no difference in their microstructures. The rcF/c and vcF/ccomposites therefore had quite close interface bonding strength (12.6 MPa and 13.0 MPa, respectively), and bending strength (106.4 MPa and 111.5 MPa, respectively). Furthermore, the rcF/ccomposites possessed comparable ablative rate with that of the vcF/ccomposites. The rcF/ccomposites derived from abandoned cF/EP composites present a great potential to be used as substitutes for vcF/ccomposites owing to their indistinguishable properties.
Bamboos are productive grasses that currently yield a high-quality wood and potentially an abundance of lignocellulose for bioenergy. All are c-3 grasses of warm habitats, where they are prone to significant photoresp...
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Bamboos are productive grasses that currently yield a high-quality wood and potentially an abundance of lignocellulose for bioenergy. All are c-3 grasses of warm habitats, where they are prone to significant photorespiratory inhibition and competitive suppression by c-4 grasses. Here, we investigate whether three bamboo species from the Brazilian cerrado (Dendrocalamus asper, Guadua angustifolia, and Guadua magna) exhibit unique adaptations that suppress photorespiratory costs and enhance photosynthetic efficiency. We evaluated photosynthetic efficiency of the bamboos and rice (Oryza sativa) by measuring c-*, the cO2 compensation point in the absence of mitochondrial respiration. At 25celcius, c-* averaged 2.81 Pa in each of the bamboo species, which is closer to a c-2 plant (2.71 Pa) than the c-3 plant rice (3.31 Pa). Assuming a chloroplast cO2 concentration of 200 mu mol mol(-1), this represents an 18% lower cost of apparent photorespiration in bamboo than rice. Light and transmission electronic microscopy of the bamboo leaves exhibited few organelles in the bundle and mestome sheath cells, and mesophyll (M) cells are deeply lobed with 99% of the cell periphery adjacent to intercellular air space covered by chloroplast and stromules. The chloroplast layer in bamboo M cells is thick, with mitochondria adjacent to or engulfed by chloroplasts. This arrangement slows cO2 efflux and facilitates refixation of photorespired cO2, which could explain the low c-* in the bamboos. The bamboos also had higher water use efficiency than rice, which may reflect efficient refixation of photorespired cO2.
The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronicconductivity of Na3V2(PO4)(3). Based on this, Na3V2(PO4)(3)/ccomposites with diverse ratios of citric a...
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The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronicconductivity of Na3V2(PO4)(3). Based on this, Na3V2(PO4)(3)/ccomposites with diverse ratios of citric acid are synthetized via rheological phase reaction way in this work. The consequences display that the Na3V2(PO4)(3)/c-1.5 composite brings a higher initial discharge capacity of 113.2 mAh g(-1) at a current rate of 1 c with coulombic efficiency above 99% during all cycles. The discharge capacity retains at 117.6 mAh g(-1) at the 100th cycle. Even at the high current densities of 5 c and 10 c, the composite also shows superior cycling performance with negligible capacity fading. Its discharge capacities decline from 97 to 92.6 mAh g(-1) at 5 c and from 85.3 to 83.7 mAh g(-1) at 10 c. These remarkable outcomes arise from its preferable morphology with suitable carbon coating because both excess and skimpy carbon seriously affect the microstructure and electrochemical properties of Na3V2(PO4)(3)/ccomposites.
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