Mechanical properties of fragrant screwpine fiber reinforced unsaturated polyester composite: Effect of fiber length,fiber treatment and water absorption

Fragrant screwpine fiber reinforced unsaturated polyester composites (FSFRUPC) were subjected to water immersion tests in order to examine the effect of water absorption on the mechanical properties. FSFRUP composite specimen containing 30 % fiber volume fraction with fiber length of 3 mm and 9 mm was considered in this study. Water absorption test was performed by immersing specimen in sea, distilled and well water at room temperature under different time durations (24, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours). The tensile, flexural and impact properties of the water absorption specimen were appraised and compared with those of the dry composite specimen as per the ASTM standard. The tensile, flexural and impact properties of FSFRUPC specimen were found to decrease with the increase in the percentage of moisture uptake. The percentage of moisture uptake of composite was reduced after alkali treatment with 3 % NaoH for 3 hours. In moisture absorption test, the lowest diffusion coefficient, D (6.62513×10^-13 m²/s) and swelling rate parameter, K _sr (6.341×10^-3 h^-1) were obtained through the specimen immersed in sea water. The chemical composition, elemental composition of fiber and surface morphology of the FSFRUPC were analysed by using Fourier transform infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively.     

How relevant is recalcitrance for the stabilization of organic matter in soils?

Traditionally, the selective preservation of certain recalcitrant organic compounds and the formation of recalcitrant humic substances have been regarded as an important mechanism for soil organic matter (SOM) stabilization. Based on a critical overview of available methods and on results from a cooperative research program, this paper evaluates how relevant recalcitrance is for the long‐term stabilization of SOM or its fractions. Methodologically, recalcitrance is difficult to assess, since the persistence of certain SOM fractions or specific compounds may also be caused by other stabilization mechanisms, such as physical protection or chemical interactions with mineral surfaces. If only free particulate SOM obtained from density fractionation is considered, it rarely reaches ages exceeding 50 y. Older light particles have often been identified as charred plant residues or as fossil C. The degradability of the readily bioavailable dissolved or water‐extractable OM fraction is often negatively correlated with its content in aromatic compounds, which therefore has been associated with recalcitrance. But in subsoils, dissolved organic matter aromaticity and biodegradability both are very low, indicating that other factors or compounds limit its degradation. Among the investigated specific compounds, lignin, lipids, and their derivatives have mean turnover times faster or similar as that of bulk SOM. Only a small fraction of the lignin inputs seems to persist in soils and is mainly found in the fine textural size fraction (<20 µm), indicating physico‐chemical stabilization. Compound‐specific analysis of ¹³C : ¹²C ratios of SOM pyrolysis products in soils with C3‐C4 crop changes revealed no compounds with mean residence times of > 40–50 y, unless fossil C was present in substantial amounts, as at a site exposed to lignite inputs in the past. Here, turnover of pyrolysis products seemed to be much longer, even for those attributed to carbohydrates or proteins. Apparently, fossil C from lignite coal is also utilized by soil organisms, which is further evidenced by low ¹⁴C concentrations in microbial phospholipid fatty acids from this site. Also, black C from charred plant materials was susceptible to microbial degradation in a short‐term (60 d) and a long‐term (2 y) incubation experiment. This degradation was enhanced, when glucose was supplied as an easily available microbial substrate. Similarly, SOM mineralization in many soils generally increased after addition of carbohydrates, amino acids, or simple organic acids, thus indicating that stability may also be caused by substrate limitations. It is concluded that the presented results do not provide much evidence that the selective preservation of recalcitrant primary biogenic compounds is a major SOM‐stabilization mechanism. Old SOM fractions with slow turnover rates were generally only found in association with soil minerals. The only not mineral‐associated SOM components that may be persistent in soils appear to be black and fossil C.     

Phenotypic variation and quantitative trait locus identification for osmotic potential in an interspecific hybrid inbred F2 poplar pedigree grown in contrasting environments

Elucidation of the mechanisms of dehydration tolerance in poplar (Populus sp.) trees will permit development of biochemical and molecular indicators to identify dehydration-tolerant genotypes during genetic selection. The objectives of this study were to characterize the degree of phenotypic variation in osmotic potential (a determinant of dehydration tolerance), determine the relationship between osmotic potential at full turgor and relative growth rate, and identify quantitative trait loci (QTL) for osmotic potential in an advanced-generation, interspecific poplar pedigree established in contrasting environments. A three-generation, sib-mated black cottonwood (Populus trichocarpa Torr. & Gray) and eastern cottonwood (P. deltoides Bartr.) segregating F(2) family (Family 331) was analyzed at a dry site east of the Cascade Mountain Range (Boardman, OR) and at a wet site west of the mountains (Clatskanie, OR). At the Boardman site, 2-year-old trees (59 clones) were either irrigated everyday (wet) or every other day (dry), whereas 3- and 4-year-old trees (58 clones) at the Clatskanie site were unirrigated. At the Boardman site, the typically narrow range of osmotic potentials exhibited by grandparents and parents was greatly expanded in the F(2) population, spanning from -1.38 to -2.35 MPa under wet conditions, with a similar range under dry conditions (-1.40 to -2.15 MPa). Clones that had osmotic potentials < or = -1.90 MPa generally displayed full maintenance of stem relative growth rates under dry conditions in contrast to clones with osmotic potentials that were < or = -1.60 MPa, in which stem relative growth rates were reduced by an average of 38% in the dry treatment relative to the wet treatment. Although osmotic adjustments of 0.13 to 0.36 MPa were observed in nine out of 59 clones, adjustment typically occurred from relatively high baseline osmotic potentials. The range in osmotic potential at the wetter Clatskanie site at age three was higher (-1.27 to -1.84 MPa) and was further expanded the following year (-1.14 to -1.94 MPa), which had a wetter spring than the previous year, followed by a typically dry July. Seven QTL for osmotic potential were identified that each explained > 7.5% of the variation in osmotic potential. Given that four clones (7%) had osmotic potentials of -2.00 MPa or less and that QTL for osmotic potential have been identified, we suggest that there are opportunities to extend the limit of dehydration tolerance in Populus.     

Ecosystem‐based forecasts of recruitment in two menhaden species

Gulf (Brevoortia patronus, Clupeidae) and Atlantic menhaden (Brevoortia tyrannus, Clupeidae) support large fisheries that have shown substantial variability over several decades, in part, due to dependence on annual recruitment. Nevertheless, traditional stock–recruitment relationships lack predictive power for these stocks. Current management of Atlantic menhaden explicitly treats recruitment as a random process. However, traditional methods for understanding recruitment variability carry the very specific hypothesis that the effect of adult biomass on subsequent recruitment occurs independently of other ecosystem factors such as food availability and predation. Here, we evaluate the predictability of menhaden recruitment using a model‐free approach that is not restricted by these strong assumptions. We find that menhaden recruitment is predictable, but only when allowing for interdependence of stock with other ecological factors. Moreover, while the analysis confirms the presence of environmental effects, the environment alone does not readily account for the complexity of menhaden recruitment dynamics. The findings set the stage for revisiting recruitment prediction in management and serve as an instructive example in the ongoing debate about how to best treat and understand recruitment variability across species and fisheries.     

EuMIXFOR empirical forest mensuration and ring width data from pure and mixed stands of Scots pine (<Emphasis Type="Italic">Pinus sylvestris L.</Emphasis>) and European beech (<Emphasis Type="Italic">Fagus sylvatica L.</Emphasis>) through Europe

Key message

This data set provides unique empirical data from triplets of Scots pine ( Pinus sylvestris L.) and European beech ( Fagus sylvatica L.) across Europe. Dendrometric variables are provided for 32 triplets, 96 plots, 7555 trees and 4695 core samples. These data contribute to our understanding of mixed stand dynamics. Dataset access at   http://dx.doi.org/10.5061/dryad.8v04m . Associated metadata available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=b3e098ca-e681-4910-9099-0e25d3b4cd52&hl=eng .

     

Differential metabolism of sulfoximine and neonicotinoid insecticides by Drosophila melanogaster monooxygenase CYP6G1

Sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ⁴-sulfanylidene] cyanamide] is in development as the first product from the new sulfoximine class of insect control agents. Highly effective against a variety of sap-feeding pest insects, available data indicate no cross-resistance to sulfoxaflor in pest insect strains that exhibit high levels of resistance to neonicotinoids and other insecticides. In vitro studies of the cytochrome P450 monooxygenase CYP6G1 from Drosophila melanogaster, expressed in a Drosophila cell line, show very high levels of metabolism for a variety of neonicotinoids, but not for sulfoxaflor and its chloropyridine-analog. A sulfoxaflor analog with nitrogen in place of the carbon in the bridge between the pyridine and sulfoximine moiety shows a modest degree of metabolism. In silico homology modeling of the CYP6G1 with the sulfoximines and neonicotinoids suggests that steric effects may limit interactions of the sulfoximines with the reactive heme-oxo complex. A distinct relationship was identified for the summed Hückel charges and the degree of metabolism observed. These observations help explain the lack of sulfoxaflor metabolism by CYP6G1, and in turn provide a basis for the lack of cross-resistance to sulfoxaflor in insecticide resistant strains of pest insects.     

Precision land leveling for sustainable rice production: case studies in Cambodia,Thailand, Philippines,Vietnam, and India

Precision Agriculture - Laser-controlled land leveling (LLL) can help improve rice production's spatial and temporal management, leading to optimized water and crop management. This research...