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971.
Xiaoyan Cao Charisma Lattao Klaus Schmidt-Rohr Jingdong Mao Joseph J. Pignatello 《Journal of Soils and Sediments》2016,16(7):1841-1848
Purpose
Sorbate-induced swelling and plasticization of sorbent have been linked to sorption hysteresis of organic compounds in the natural organic matter of isolated humic acids, soils, and coals. The above processes, which have important implications for the fate and bioavailability of organic and inorganic contaminants, are mostly based on macroscopic changes and require molecular-level confirmation. This study aimed to investigate the presence or absence of sorbate-induced plasticization of Pahokee peat soil as a function of different sorbates.Materials and methods
The plasticization of Pahokee peat soil was studied upon sorption of different proton-free solutes including C6D6, CDCl3, CCl4, C2Cl4, CBr4, C6D5Cl, and C5D5N, covering apolar and polar aromatic and aliphatic compounds. The swelling and plasticization of Pahokee peat soil were verified at the molecular level by 1H wideline and two-dimensional wideline separation (2D WISE) NMR. The use of 1H wideline shapes is the traditional technique for studying molecular dynamics but hampered by the lack of spectral resolution, with one dimension displaying 13C chemical shifts and the second showing 1H wideline shapes, is capable of providing information on molecular dynamics of specific functional groups.Results and discussion
Our results showed that the segments of Pahokee peat soil sorbed with C6D6, C2Cl4, and C5D5N became more mobile, but the changes due to the plasticization were small. Both C6D6 and C5D5N selectively increased the mobility of specific components, C6D6 of the nonpolar alkyl domains, and C5D5N of both the nonpolar alkyl domains and aromatic components.Conclusions
Some liquid solutes at high concentrations (2–5 wt%) are capable of slightly “softening” natural organic matter of a soil, and this provides support for the hypothesis that natural organic matter in Pahokee peat soil is in a glassy state that is subject to plasticization.972.
Lulu Cheng Inyoung Kim Herbert Pang 《Journal of Agricultural, Biological & Environmental Statistics》2016,21(4):641-662
In this paper, we propose a semiparametric regression approach for identifying pathways related to zero-inflated clinical outcomes, where a pathway is a gene set derived from prior biological knowledge. Our approach is developed by using a Bayesian hierarchical framework. We model the pathway effect nonparametrically into a zero-inflated Poisson hierarchical regression model with an unknown link function. Nonparametric pathway effect was estimated via a kernel machine, and the unknown link function was estimated by transforming a mixture of the beta cumulative density function. Our approach provides flexible nonparametric settings to describe the complicated association between gene expressions and zero-inflated clinical outcomes. The Metropolis-within-Gibbs sampling algorithm and Bayes factor were adopted to make statistical inferences. Our simulation results support that our semiparametric approach is more accurate and flexible than zero-inflated Poisson regression with the canonical link function, which is especially true when the number of genes is large. The usefulness of our approach is demonstrated through its applications to the Canine data set from Enerson et al. (Toxicol Pathol 34:27–32, 2006). Our approach can also be applied to other settings where a large number of highly correlated predictors are present.Supplementary materials accompanying this paper appear on-line. 相似文献
973.
Eric van Hullebusch Philippe Chatenet Véronique Deluchat Philippe M. Chazal Didier Froissard Michel Botineau Axel Ghestem Michel Baudu 《Water, air, and soil pollution》2003,150(1-4):3-22
Copper sulfate (CuSO4) addition to freshwater for phytoplankton control has been practiced for decades, and remains the most effective algicidal treatment for numerous managed water bodies. A reservoir in the centre of France was the site for an investigation of copper distribution in aquatic systems after a copper sulfate treatment. Results of monitoring showed a rapid conversion of dissolved Cu to particulate forms, with significant accumulation in the sediments. Total sediment Cu content increased from approximately 37.7 to 45.4 μg g-1 dry weight after the first treatment. Sequential extraction suggested that a significant portion of the sediment-borne Cu was associated with the organic fraction which may release Cu to the water column, although significant release would occur only under extreme changes in water chemistry. Based upon measured Cu concentrations, flows at the down-stream water, and known mass applied during treatment, mass balance calculations indicated that approximately 17% of the Cu was exported from the reservoir over a 70 day period following a 196 μg L-1 Cu2+ (as CuSO4·5H2O) treatment.Copper bioaccumulation by a moss, Fontinalis antipyretica in the down-stream water showed that it was possible to distinguish between a treated and an untreated area. The impact of copper treatmentin the down-stream reservoir could be followed using mosses. There is a distance effect which could be exploited to determine potential copper impact for example. The largest amount of copper was probably adsorbed on downstream sediment or lost in running water. Thirty days after copper sulfate addition, Fontinalis still indicatedcopper exposure. 相似文献
974.
Yvonne Lokko Alfred Dixon Sam Offei Eric Danquah Martin Fregene 《Genetic Resources and Crop Evolution》2006,53(7):1441-1453
A study was conducted to determine the extent of genetic diversity among African cassava (Manihot esculenta Crantz) accessions resistant to the cassava mosaic virus disease (CMD), using simple sequence repeat (SSR) markers. The accessions
included a breeding stock (clone 58308), five improved lines, 62 CMD resistant and 10 CMD susceptible landraces. Genetic diversity
was assessed among accessions in five cluster groups derived from UPGMA analysis on data from 18 SSR primer pairs. Average
gene diversity, He, was high in all cluster groups, with an average heterozygosity of 0.591 ± 0.061. The estimator of inbreeding
Fis revealed a low level of inbreeding within groups and averaged −0.262 ± 0.142. Gene diversity among all accessions was
51.4% and gene diversity within cluster groups was 46.6%, while 4.8% was due to diversity between the different cluster groups.
The amount of genetic differentiation measured by Gst and Fst were 9.6% and 12.1% respectively, indicating a weak genetic
structure. 相似文献
975.
Determination of the conjugated linoleic acids in cow's milk fat by Fourier transform Raman spectroscopy 总被引:1,自引:0,他引:1
Meurens M Baeten V Yan SH Mignolet E Larondelle Y 《Journal of agricultural and food chemistry》2005,53(15):5831-5835
The collective term "conjugated linoleic acid" or "CLA" generally refers to a mixture of conjugated positional and geometric isomers of linoleic (cis-9,cis-12-octodecadienoic) acid. In nature, these isomers are mainly formed in the rumen by biohydrogenation of polyunsaturated fatty acids. This study concerns a first trial of CLA determination in cow's milk fat by Raman spectroscopy. The spectra of pure cis-9-oleic, cis-9,cis-12-linoleic, cis-9,trans-11-linoleic, and trans-10,cis-12-linoleic acids have been examined in comparison with the spectra of selected milk-fat samples containing between 0 and 3% of CLA. The trial of CLA determination by Raman spectroscopy on cow milk fat has reached its objective with the two following results. First, the examination of the Raman spectra allows to identify three specific Raman signals of the chemical bonds associated to the cis,trans conjugated C=C in the rumenic and trans-10,cis-12-octodecadienoic acids at 1652, 1438, and 3006 cm(-1). Second, the calibration of Raman spectrometer for the CLA determination has indicated that these three specific signals suit very well for the accurate and reliable measurement of CLA concentration in milk fat. To our knowledge, the present study is the first successful attempt to determine the CLA content of milk fat by a spectrophotometric method. 相似文献
976.
Reactions of anthocyanins and tannins in model solutions 总被引:1,自引:0,他引:1
Salas E Fulcrand H Meudec E Cheynier V 《Journal of agricultural and food chemistry》2003,51(27):7951-7961
The reaction between procyanidin dimer Ec-EcG (B2 3'-O-gallate) and malvidin 3-O-glucoside (Mv3glc) was studied in a model solution system at two different pH values, 2.0 and 3.8. Disappearance of both species was much faster at pH 3.8 than at pH 2.0. That of Mv3glc was increased in the presence of Ec-EcG, whereas that of Ec-EcG was the same in the presence or absence of the anthocyanin. Values of absorbance at 520 nm measured at pH 2.0 were correlated with the amount of residual Mv3glc. Those measured at pH 3.8 hardly changed during the incubation, but absorbance values at 420 and 620 nm as well as resistance to sulfite bleaching were much increased, confirming that Mv3glc was converted to other pigments. Anthocyanin-flavanol adducts were observed at both pH values, but their structures were different. At pH 2.0, cleavage of the procyanidin linkage followed by nucleophilic addition of flavanol or anthocyanin moieties led to (Ec)(n)-EcG and (Ec)(n)-Mv3glc, respectively. At pH 3.8, nucleophilic addition of Ec-EcG onto the anthocyanin yielded Mv3glc-(Ec-EcG). 相似文献
977.
Javier M. Gonzalez Douglas R. Smith Stan Livingston Elizabeth Warnemuende-Pappas Martha Zwonitzer 《Journal of Soils and Sediments》2016,16(7):1921-1932
Purpose
In a 6-year study, we investigated the effectiveness of blind inlets as a conservation practice in reducing pesticide losses compared to tile risers from two closed farmed depressional areas (potholes) in the US Midwest under a 4-year cropping rotation.Materials and methods
In two adjacent potholes within the same farm and having similar soils, a conventional tile riser and blind inlet were installed. Each draining practice could be operated independent of each other in order to drain and monitor each depression with either practice. Sampling events (runoff events) were collected from the potholes from 2008 to 2013 using autosamplers. The samples were analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine.Results and discussion
The results of this study demonstrated that the blind inlet reduced analyzed pesticide losses; however, the level of reduction was compound dependent: atrazine (57 %), 2,4-D (58 %), metolachlor (53 %), and glyphosate (11 %).Conclusions
Results from this study corroborate previous research findings that blind inlets are an effective conservation practice to reduce discharge and pollutants, including pesticides from farmed pothole surface runoff in the US Midwest.978.
Susheel Verma Jawahar L. Karihaloo Shailesh K. Tiwari Rani Magotra Awtar K. Koul 《Genetic Resources and Crop Evolution》2007,54(2):221-229
Eremostachys superba Royle ex Benth. (Lamiaceae) has undergone a severe decline in population size since its discovery in the North-western Himalayas
in late 19th century. One hundred and seventy-two plants from six populations in the Indian states of Uttar Pradesh and Jammu
& Kashmir, located between 0.45 km and 455.72 km apart from each other were evaluated for RAPD polymorphism. Sixteen random
primers generated 92 bands overall, 77 of which were polymorphic. Shannon’s index of genetic diversity within populations
(H
o) ranged between 0.305 and 0.421; the average within-population diversity (H
pop) was 0.389; and the total species diversity (H
sp) was 0.478. The population from Mohand (representing the type locality) had the fewest plants, at 18, and was genetically
the most depauperate. Among the other populations, ranging in size between 52 and 1,022 individuals, no relation between population
size and genetic diversity was evident. It is suggested that these six populations represent relics of a larger, extended
population, in which the presence of perennating rootstocks has helped preserve historic patterns of genetic diversity. AMOVA
revealed that 83.01% of the variation exists within populations, which was consistent with earlier studies on the reproductive
biology of E. superba, which indicated this species is predominantly allogamous. FST distances between all populations were significant, indicating
geographic differentiation despite some of them being closely separated. Habitat restoration and protection from indiscriminate
harvesting are proposed as primary strategies for conserving E. superba. Rejuvenation of the Mohand population through intrapopulation crossing between plants bearing diverse molecular phenotypes
is also suggested. 相似文献
979.
Xiao-Ping Jia Yun-Su Shi Yan-Cun Song Guo-Ying Wang Tian-Yu Wang Yu Li 《Genetic Resources and Crop Evolution》2007,54(2):233-236
The development of EST-SSR in foxtail millet (Setaria italica) for polymorphism and transferability study was reported here. From 1213 EST sequences, 30 SSRs were obtained and primers
were designed for 26 SSRs. Among them, four pairs of SSR primers amplified polymorphic products in 12 foxtail millet cultivars
and one accession of Setaria viridis, a wild relative of foxtail millet, with 10 alleles detected for the four loci and 2.5 alleles per locus. In addition, ten
SSR markers could be transferred to other nine Gramineae species. The putative functions of 11 ESTs containing polymorphic
and transferable SSRs were also identified. 相似文献
980.
In industrial areas, heavy metals may accumulate in forest soil organic horizons, affecting soil microorganisms and causing
changes in the chemical composition of the accumulated organic matter. The objectives of this study were to test the ability
of near-infrared spectroscopy (NIRS) to detect heavy metal effects on the chemical composition of forest soil O horizons and
to test whether NIRS may be used to quantitatively determine total and exchangeable concentrations of Zn and Pb (Znt, Pbt, Znex, Pbex) and other chemical and microbial properties in forest soil O horizons polluted with heavy metals. The samples of O horizons
(n = 79) were analyzed for organic C (Corg), total N and S (Nt, St), Znt, Pbt, Znex, Pbex, basal respiration (BR), microbial biomass (Cmic) and Cmic-to-Corg ratio. Spectra of the samples were recorded in the Vis-NIR range (400–2,500 nm). To detect heavy-metal-induced changes in
the chemical composition of O horizons principal components (PC1–PC7) based on the spectral data were regressed against Znt + Pbt values. A modified partial least squares method was used to develop calibration models for prediction of various chemical
and microbial properties of the samples from their spectra. Regression analysis revealed a significant relationship between
PC3 and PC5 (r = −0.27 and −0.34, respectively) and Znt + Pbt values, indicating an effect of heavy metal pollution on the spectral properties of the O horizons and thus on their chemical
composition. For quantitative estimations, the best calibration model was obtained for Corg-to-Nt ratio (r = 0.98). The models for Corg, Nt, and microbial properties were satisfactory but less accurate. NIRS failed to accurately predict St, Corg-to-St, Znt, Pbt, Znex, and Pbex. 相似文献