Search

Organic thin layers are highlighted as crucial components of flexible and printed electronic products due to their ability to provide mechanical flexibility in various applications, such as flexible displays and wearable electronics. The thickness and uniformity of these layers are crucial factors that influence surface planarization, mechanical stress relief, and the enhancement of optical performance. Therefore, accurate measurement of their thickness distribution is essential. In this study, the two-dimensional thickness distributions of spin-coated and inkjet-printed organic microlayers on glass substrates were measured using a light extinction image method. Using a 300 nm wavelength light source and a camera, images with an area of 4872 × 3640 μm2 and an XY resolution of 3.5 μm were obtained through single measurements. The precision of the measured thickness could be enhanced to several nanometers through pixel binning and image overlaying. Using this light extinction measurement system, we measured and analyzed the thickness distribution of the center and edge of the spin-coated and inkjet-printed organic layers with thicknesses of several micrometers. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the N storage capacity of litterfall and its impact on C mineralization in beech forests. The research was conducted at 15 sample plots under European beech stands located in different ecological conditions on the territory of Serbia. More than half (53%) of the sample plots are characterized by low and very low litterfall N content (

The eluvozems and soddy eluvozems on two-layered deposits dominating in the soil cover of the Zvenigorod Biostation of Moscow State University, contain, on average, 65–83 t/ha of organic carbon in the organic layer and the upper meter of mineral strata. Carbon stock is minimal (59–68 t/ha) in the coarser-textured soddy eluvozem of the spruce forest and reaches 76–92 t/ha in soils of birch–spruce and pine–spruce forests. Organic layers store 3.3–5.8 t C/ha or 4–9% of the total soil organic carbon stock; the upper mineral layer (0–20 cm) stores 64–69%. Different levels and profile distribution of organic carbon in soils are determined by lithological and textural features of the soil profiles and by the nature of vegetation. The contribution of water-extractable organic carbon to the total organic carbon content in the upper mineral horizons does not exceed 1.3–1.8%; the contribution of microbial carbon is 1.7–2.4%. In acidic loamy soils, the enrichment in calcium and potassium, the cation exchange capacity, the content of exchangeable bases, and the degree of base saturation can serve as indicators of the content and stocks of organic carbon at the ecosystem level. The relationship with the content of clay fractions and oxalate-extractable Al and Fe is manifested to a lesser extent due to the similar origin and properties of soils. The variability of organic carbon stocks in soils is largely determined by its content, the influence of which decreases with depth. Accounting for spatial heterogeneity, field measurements of the soil bulk density and proportion of fine earth, and correct analytical determinations are essential components of the assessment of carbon stocks in soils of forest ecosystems as a part of the national monitoring system for carbon pools and greenhouse gas fluxes. [ABSTRACT FROM AUTHOR]

Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic surface. In this work, three heterocyclic compounds such as 1-azanaphthalene-8-ol (8-AN), 2-methylquinoline-8-ol (8-MQ), and 8-quinolinol-5-sulfonic acid (8-QSA) were used as green compounds, and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface analysis. Findings found that the electrochemical performance was improved in the order of 8-AN > 8-MQ > 8-QSA, demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium surface. From the electrochemical performance, the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments, with potential inhibition efficiency of 87.4%, 99.0%, and 99.9% for 8-QSA, 8-MQ, and 8-AN, respectively. Quantum chemical parameters and electron density distribution for free organic species in the absence and presence of Mg2+ cation were evaluated using density functional theory (DFT). Upon the formation of coordination complexes between organic compound and Mg2+, energy gap underwent change about ∆E = 5.7 eV in the 8-AN/Mg2+ system. Furthermore, the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms, which further confirmed by the electron density difference and projected density of states analyses. Based on theoretical calculations, three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C, O and N atoms. In the parallel configuration, the C-Mg, N-Mg and O-Mg bond distances are between 2.11 and 2.25 Å, whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40 Å (covalent bonds via O and N atoms). The results indicated that parallel configurations are energetically more stable, in which the adsorption energies are -4.48 eV (8-AN), -4.28 eV (8-MQ) and -3.82 eV (8-QSA) compared to that of perpendicular adsorption (-3.65, -3.40, and -2.63 eV). As a result, experimental and theoretical studies were in well agreement and confirm that the nitrogen and oxygen atoms will be the main adsorption sites.

The electrochemical and surface properties of mild steel in stagnant aerated solutions containing 5 mM citric acid at pH 5 and pH 9 were investigated by open circuit potential, potentiodynamic polarization and electrochemical impedance measurements combined with X-ray photoelectron spectroscopy (XPS) characterization. The results show that the active dissolution behavior of steel in the citric acid solution at pH 5 is well described using a kinetic model consisting of a modified consecutive mechanism, in parallel with a catalytic path involving the divalent intermediate Fe[(OH)2)]ads. The surface film is composed of FeO, Fe(OH)2, FeOOH and Fe-citrate. Also, the analysis of in-depth distribution of composition indicates a high coverage of the organic layer. In the pH 9 citrate solution, a thin bilayer passive film was formed (with Fe(II) and Fe(III) located mainly in the inner and outer regions, respectively). Its overall composition is Fe3O4/FeOOH. Electrochemical measurements revealed the low protective ability of this film and this was confirmed by a modest XPS intensity ratio of Fe(III)/Fe(II). Moreover, no clear presence of Fe-citrate was detected in the passive film, and so the poor passivation behavior was correlated to insufficient adsorption of the tri-ionized citrate anion. The importance of solution flow to stimulate the adsorption of citrate anion is emphasized. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the N storage capacity of litterfall and its impact on C mineralization in beech forests. The research was conducted at 15 sample plots under European beech stands located in different ecological conditions on the territory of Serbia. More than half (53%) of the sample plots are characterized by low and very low litterfall N content (<8 g·kg-1; 9-12 g·kg-1), and a wide C/N ratio, which indicates a slow decomposition of the organic soil layer. These results could be useful indicators of the capacity and dynamics of litterfall N storage and its impact on C mineralization in the context of preserving biodiversity, stability, and longevity of beech forests in Serbia. [ABSTRACT FROM AUTHOR]

This study examined the distribution of culturable fungi and predominant genera in the organic layer and in the upper layers of the mineral soil of six broad-leaved tree plantations in autumn, after the full fall of leaves. In total, 1335 fungal isolates were recovered from an organic layer and two mineral layers (0–4 cm and 5–8 cm) of soil. The structure of fungal genera differed in the tree plantations and in the three studied soil layers. The organic layer was the layer most populated by fungi compared to the mineral layers. In the organic layer, Penicillium and phyllosphere fungi such as Cladosporium and Phoma dominated. Deeper in the soil, the dominance of certain genera decreased with the increase in Trichoderma, Mucor, Mortierella, and entomopathogenic fungi such as Paecilomyces and Beauveria. Penicillium was one of the most abundant fungi in all soil layers studied. [ABSTRACT FROM AUTHOR]

• 8-AN, 8-MQ, and 8-QSA chimisorbed on Mg(0001) surface via covalent bonds formation. • Upon the formation of coordination complexes between 8-AN and Mg2+, energy gap underwent change about ∆ E = 5.7 eV. • 8-AN, 8-MQ, and 8-QSA in their parallel configurations are found to interact strongly with the Mg atoms. • Electron donor effect of 8-AN compound strongly increases its coordination to Mg(0001) surface. • Interaction energies of all geometries follow the electrochemical performance trends. Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic surface. In this work, three heterocyclic compounds such as 1-azanaphthalene-8-ol (8-AN), 2-methylquinoline-8-ol (8-MQ), and 8-quinolinol-5-sulfonic acid (8-QSA) were used as green compounds, and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface analysis. Findings found that the electrochemical performance was improved in the order of 8-AN > 8-MQ > 8-QSA, demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium surface. From the electrochemical performance, the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments, with potential inhibition efficiency of 87.4%, 99.0%, and 99.9% for 8-QSA, 8-MQ, and 8-AN, respectively. Quantum chemical parameters and electron density distribution for free organic species in the absence and presence of Mg2+ cation were evaluated using density functional theory (DFT). Upon the formation of coordination complexes between organic compound and Mg2+, energy gap underwent change about ∆ E = 5.7 eV in the 8-AN/Mg2+ system. Furthermore, the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms, which further confirmed by the electron density difference and projected density of states analyses. Based on theoretical calculations, three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C, O and N atoms. In the parallel configuration, the C-Mg, N-Mg and O-Mg bond distances are between 2.11 and 2.25 Å, whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40 Å (covalent bonds via O and N atoms). The results indicated that parallel configurations are energetically more stable, in which the adsorption energies are -4.48 eV (8-AN), -4.28 eV (8-MQ) and -3.82 eV (8-QSA) compared to that of perpendicular adsorption (-3.65, -3.40, and -2.63 eV). As a result, experimental and theoretical studies were in well agreement and confirm that the nitrogen and oxygen atoms will be the main adsorption sites. [ABSTRACT FROM AUTHOR]

The haloalkaliphilic genus Thioalkalivibrio, widely used in bio-desulfurization, can oxidize H2S to So, which is excreted outside cells in the form of biosulfur globules. As by-product of bio-desulfurization, information on biosulfur globules is still very scant, which limits its high-value utilization. In this paper, the characteristics of biosulfur globules produced by Thioalkalivibrio versutus D301 and the possibility of cultivating sulfur-oxidizing bacteria as a high biological-activity sulfur source were studied. The sulfur element in the biosulfur globules existed in the form α-S8, which was similar to chemical sulfur. The biosulfur globule was wrapped with an organic layer composed of polysaccharides and proteins. The composition of this organic layer could change. In the formation stage of biosulfur globules, the organic layer was dominated by polysaccharides, and in later stage, proteins became the main component. We speculated that the organic layer was mainly formed by the passive adsorption of organic matter secreted by cells. The existence of organic layer endowed biosulfur with better bioavailability. Compared with those found using chemical sulfur, the growth rates of Acidithiobacillus thiooxidans ATCC 19377T, Thiomicrospira microaerophila BDL05 and Thioalkalibacter halophilus BDH06 using biosulfur increased several folds to an order of magnitude, indicating that biosulfur was a good sulfur source for cultivating sulfur-oxidizing bacteria. [ABSTRACT FROM AUTHOR]

In this work, we study the physical properties of hybrid organic/inorganic mixture semiconducting layers. Materials selected for the research were poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4- b0]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] and nanostructured cadmium sulfide (CdS) powder. These materials have been chosen due to their narrow optical band gap combined with high chargecarrier mobility, which makes them interesting for application as components of active layers in bulk p-n heterojunctions. In particular, we present the results of studies on the influence of CdS content on the physical properties of thin hybrid films. The ellipsometric measurements showed that the composition of the base layers influenced their optical properties without significantly influencing their thermal stability. [ABSTRACT FROM AUTHOR]

This study examined the distribution of culturable fungi and predominant genera in the organic layer and in the upper layers of the mineral soil of six broad-leaved tree plantations in autumn, after the full fall of leaves. In total, 1335 fungal isolates were recovered from an organic layer and two mineral layers (0–4 cm and 5–8 cm) of soil. The structure of fungal genera differed in the tree plantations and in the three studied soil layers. The organic layer was the layer most populated by fungi compared to the mineral layers. In the organic layer, Penicillium and phyllosphere fungi such as Cladosporium and Phoma dominated. Deeper in the soil, the dominance of certain genera decreased with the increase in Trichoderma, Mucor, Mortierella, and entomopathogenic fungi such as Paecilomyces and Beauveria. Penicillium was one of the most abundant fungi in all soil layers studied.

Nutrient storage in the forest floor is regulated through litter decomposition and nutrient cycling. Stoichiometry of nutrients can provide characterization of the forest floor. To quantify nutrient storage in the forest floor and to determine stoichiometry among different forest types, available data on nutrients were meta-analyzed. The data on nutrients--nitrogen, phosphorus, potassium, calcium, and magnesium--were collected from published reports and original data on Japanese forests. The relationship between nutrient storage and forest floor mass was also examined. Japanese cypress and cedar plantations had small N and P storage in the forest floor with high C:N and C:P ratios, whereas subalpine conifers had large N and P storage in the forest floor with low C:N and C:P ratios; cedar plantations showed large Ca-specific storage in the forest floor. The stoichiometry of the forest floor varied between different forest types, namely C:N:P ratios were 942:19:1 for cedar and cypress plantations, 625:19:1 for broad-leaved forests, and 412:13:1 for subalpine conifers and fir plantations. N storage was closely correlated; however, P and other mineral storages were weakly correlated with the forest floor mass. Nutrient storage and stoichiometry can provide a better perspective for the management of forest ecosystem. [ABSTRACT FROM AUTHOR]

Key message: In the organic layer, absorptive fine roots of Larix gmelinii represent a significant proportion of the total fine-root biomass and can morphologically adjust during the growing season to optimize resource acquisition. Larix gmelinii is a foundational tree species in forests of northern China and Far-East Russia. A better understanding of the species' belowground resource acquisition strategy is important for soil nutrient and carbon estimates. Here, we investigated seven traits of absorptive fine-roots at four depth levels, from the organic layer (organic, decomposed litter from dead plants) down to a soil depth of 30 cm in May, July and September of 2016. Biomass and functional traits of absorptive fine roots varied significantly, indicating the species ability to adjust its resource acquisition across the four depth layers. From the organic layer to deeper mineral soil layers, root diameter and tissue density increased, while specific root length decreased, in other words, roots become longer and thinner with increasing values of soil water and nutrient concentrations. At the same time, the average biomass and length of absorptive fine roots in the organic layer accounted for 14% and 16% of the total, respectively. With increasing soil depth, the averaged proportion of biomass and length density of absorptive fine roots to the total fine roots decreased significantly from almost 57 to 32%, and 80–62%, respectively. Finally, total soil nitrogen concentration showed the strongest link with absorptive fine-root traits, such as root diameter, specific root length, root standing biomass and length density. Our results indicate that absorptive fine roots in the organic layer play a crucial role in belowground resource acquisition and carbon cycle in a common and economical important species. [ABSTRACT FROM AUTHOR]

Surface chemistry is a significant field of research, especially for the preparation of organic-inorganic hybrid materials in which nearly every atom is anchored at the interface. Herein we report on the functional binding agents (FBAs), Mg(OH) 2 or Co(OH) 2 –Mg(OH) 2 –Co(OH)(NO 3), as efficient tools for functionalising surfaces, whereby the morphology and growth of the organic-inorganic coating can be varied by varying the interfacial composition to achieve improved functionality. To demonstrate the potential of this strategy, we combine plasma electrolytic oxidation (PEO) and a two-step dip chemical coating (DCC) technique to deliver multi-layered constructions of several chemical compositions comprising inorganic and organic components. A novel single layer of FBAs is fabricated on the rough inorganic coating through chemical treatment via DCC, transforming it into a binding site for primary clusters of 2-mercaptobenzimidazole (MBI) molecules. Thus, FBAs form coordination complexes with organic molecules, which grow on FBA surfaces. Finally, electrochemical measurements reveal that the self-assembly of organic-inorganic hybrid heterostructures appreciably suppresses metal oxidation and oxygen reduction, due to a synergistic effect arising from the combination of FBAs with organic and inorganic coatings. [ABSTRACT FROM AUTHOR]

Flower-like organic materials have been used for applications in supercapacitors, catalysis, corrosion science, but no report of "flower" from metal-organic compounds on porous inorganic surface has been available. Here, we report the successful fabrication of flowerlike organic-inorganic materials via the combination of TiO 2 -MgO film prepared on magnesium alloy through plasma electrolytic oxidation (PEO) as inorganic components and metal-quinoline, Na-8-hydroxyquinoline-5-sulfonic acid (NaHQS) and Co(II)-8-hydroxyquinoline-5-sulfonic acid (CoHQS), as the organic component. Interaction between the CoHQS complex and the porous inorganic materials then leads to the formation of flowerlike organic-inorganic coating on the magnesium surface. Furthermore, a detailed analysis of surface morphologies indicates that MHQS molecules are linked together via kinds of intermolecular hydrogen bonds and non-covalent π-π bonds between heterocyclic molecules. PEO-TiO 2 -CoHQS and PEO-TiO 2 -NaHQS exhibit enhanced electrochemical performance and chemical stability compared with the free MHQS, which was discussed based on polarization and impedance interpretation. This is attributed to the physical and chemical adsorption on the coating surface as well as the high surface area of the CoHQS in the nanoflowers. [ABSTRACT FROM AUTHOR]

In tropical ecosystems, interactions between arbuscular mycorrhizal fungi (AMF) and other organisms have been little studied, but may be of significant importance for understanding the role of AMF in decomposition processes and nutrient cycling. In this study, we used ingrowth cores to investigate the impacts of regular rotation of the cores, defaunation and nitrogen addition on AMF, microbial biomass and microarthropods in the fermentation/humus (F/H) and litter (L) layers of an Ecuadorian montane tropical rainforest. AMF were substantially reduced in the F/H layer (to 34% of initial), while in the L layer they remained constant during the experiment. Overall, microorganisms and microarthropods were largely independent of AMF hyphae and their exudates, however, defaunation strongly affected the recovery of their communities. Nitrogen addition increased the quality of litter material and beneficially affected microbial communities thereby increasing decomposition rates, but did not impact AMF abundance and microarthropod communities. These findings suggest that the cutoff of the carbon supply from the plant to the fungal mycelium was not compensated by switching resources in the F/H layer, underlining a strong association between AMF and living roots. While in the L layer, AMF likely competed with saprotrophic microorganisms for litter-derived resources at intermediate stages of decomposition pointing to indirect contributions of AMF to decomposition processes. Overall, the results support the view that root-derived resources are important in fueling soil food webs, but also indicate that in the studied montane rainforest these resources are only available close to roots and not channeled distant to roots via AMF. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We report a molecular self-assembly to create the basket-weave organic structure. • Primary clusters of dimethyl-5-hydroxyisophthalate precipitated on the porous coating. • Basket-weaves are linked together through kinds of non-covalent interactions. • Molecule agglomerates of basket-weave organic component are the primary source for extraordinary electrochemical stability. Abstract An organic-inorganic hybrid coating with spatial structures is known to be potential for biology, catalysis, and electrochemistry, but no report of basket-weave structure made from organic component has been available. Here, we report a molecular self-assembly to create the basket-weave organic structure using dimethyl-5-hydroxyisophthalate (DMIP). Primary clusters of DMIP precipitated on the porous surface of inorganic layer by the use of beneficial effect of the micro-defects which triggers the physical locking activated by charge-transfer phenomena. Then, the organic chain grows on a certain plane, resulting from the non-covalent π-π stackings between short-range ordered aromatic cores as well as the interactions between polar functional groups. A detailed analysis on surface morphologies suggests that two adjacent basket-weaves are linked together through kinds of non-covalent interactions between functional groups of each weave. Thus, the molecule agglomerates of basket-weave organic component formed on defective inorganic layer are the primary source for extraordinary electrochemical stability. [ABSTRACT FROM AUTHOR]

Highlights • Forest fragmentation is widespread in Mongolia's forest-steppe ecotone. • It is known to increase the drought sensitivity of tree growth in these forests. • Here the hypothesis was tested whether fragmentation degrades the organic carbon pool. • Organic layer carbon stock density increased with stand size. • Total ecosystem carbon stock density did not vary with stand size and isolation. Abstract The hypothesis was tested that the size and the degree of isolation of Larix sibirica forests in the forest-steppe ecotone of Mongolia affects aboveground and belowground carbon pool densities. The research question was based on the fact that both microclimate and the drought sensitivity of stemwood production were earlier shown to differ with stand size and isolation in this ecotone. Contrary to our hypothesis, we did not find significant differences in the organic carbon stock densities of the tree biomass and the mineral soil. The depth, carbon content and carbon stock density of the organic layer increased with stand size, but was not a major determinant of total ecosystem carbon stock density. Nevertheless, the increasing depth and the increasing humus content of the organic layer with stand size could be significant by improving moisture availability and, thus, promoting forest regeneration. Furthermore, reduced organic layer thickness and humus content and thus water storage capacity could be one out of several causes of the previously observed higher drought vulnerability of stemwood formation in small forest stands of the Mongolian forest-steppe. A mean carbon stock density of 237 Mg C ha−1 for total ecosystem organic carbon stock density matches with earlier estimates for Mongolia's boreal forest corroborating the view that the ecosystem carbon pool density at the southern edge of the boreal forest is lower compared to forests at higher latitudes with even colder climate and deeper and more widespread permafrost. [ABSTRACT FROM AUTHOR]

Highlights • Among-site variation in the total fine root biomass was not explained by latitude. • Fine root density increased in the organic layer towards the north. • The future climate may shift fine roots from the organic layer to the mineral soil. Abstract The geographical patterns in the distribution of fine root biomass (FRB) and in the contribution of fine roots to below-ground nitrogen and carbon stocks are poorly documented. Here, we examined FRB and the ecological factors that govern it, along a 1000 km long latitudinal gradient in unmanaged mixed boreal forests in North-East Europe. We sampled fine roots (diameter ≤2 mm; trees and field layer vegetation combined) twice per growing season in 2015 and 2016 from ten sites spaced one degree of latitude between 60°N (near St. Petersburg) and 69°N (near Murmansk, Russia). We separated living fine roots. The roots were dried and weighed; tissue carbon and nitrogen concentrations were measured. The obtained values were correlated with climatic, plant community and soil characteristics. Among-site variation in the total FRB and carbon and nitrogen concentrations were not explained by latitude or by climatic, plant community or soil characteristics. However, fine root density in the organic layer increased towards the north. The more superficial root system in the north than in the south may indicate a poleward increase in the vulnerability of boreal forests to abiotic risks (forest fires, drought). Our results suggest that the future climate may shift fine roots as well as carbon and nitrogen cycling from the organic layer to mineral soils, thereby increasing the volume of soil utilized by fine roots for water and nutrient uptake. [ABSTRACT FROM AUTHOR]

Mountain shrublands in semi-arid zones have a relevant effect in protecting water and soil, and conserving biodiversity. Nutrient availability in vegetation layers of semi-arid shrublands, may increase biomass production and litter accumulation rates that may affect the soil nutrient cycle through the positive feedback. However, the effect of semi-arid mountainous shrublands on litter quality and soil properties is poorly studied. To fill these gaps, we studied different vegetation types (i.e., Ulmus carpinifolia Gled., Berberis integerrima Bunge, Malus orientalis Ugl., Pistacia atlantica Desf., Amygdalus lycioides Spach., Rhus coriaria L., Cotoneaster kotschyi Klotz. and Juniperus excelsa M. Bieb.), to assess litter quality, soil properties, and C and N mineralization in Iran. Totally, 240 litter or organic horizon and topsoil (0–10 cm depth) samples were taken under the studied vegetation types. Based on analysis of variance and Tukey test, soil fauna (earthworms, acarina, collembola, nematode, protozoa), microflora (bacteria and fungi), microbial (basal and substrate-induced respirations, microbial biomass) and enzyme (urease, acid phosphatase, arylsulfatase and invertase) properties, as well as C and N mineralization were highest under deciduous species, especially U. carpinifolia vegetation type. Conversely, J. excelsa , as an evergreen species, decreased soil quality bio-indicators by decreasing litter quality and soil fertility in the high mountain vulnerable semi-arid sites. Based of heat plots of principal component analysis, soil biological and biochemical properties, especially enzyme indicators, created hot spots of soil quality under the studied vegetation types. As a conclusion, deciduous species are the hotspot's bioindicator in the mountainous ecosystems, indicating their potential role in enriching soil nutrient cycles. • Different shrublands strongly affected litter chemistry in a semi-arid montane environment. • Soil functions increased under deciduous vegetation types, especially Ulmus carpinifolia. • Juniperus excelsa , as an evergreen vegetation type, decreased soil quality bio-indicators. • Litter quality and soil fertility are the main drivers of soil biota activities. [ABSTRACT FROM AUTHOR]

Abstract: Drying and rewetting (D/W) of soils often resulted in the release of soluble phosphorus (P) and nitrogen (N), thereby changing the availability of both nutrients. Most experiments on D/W have been conducted with disturbed mineral soil samples and with rewetting of the soil samples by abrupt change in the water potential. Here, we studied the effect of D/W on the leaching of P and N from undisturbed forest floors of a European beech and a Norway spruce site under near field conditions of desiccation and rewetting. We hypothesized that even under realistic rewetting of undisturbed forest floors, the leaching of P and N is increased after D/W and that the effects are less pronounced for spruce than for beech because of the larger hydrophobicity of the spruce forest floor. Undisturbed forest floor columns were subjected to desiccation at 20°C until a matrix potential of –100 MPa (pF 6.0) was reached, while controls were kept at moist conditions. Columns were irrigated by 22 mm day−1 from day 1–3 and by 10 mm day−1 from day 4–14 given in automated short pulses. Leachates from the soil columns were analyzed for orthophosphate, total P, NH4, NO3, and total N. In the spruce forest floor the concentrations of total P in leachates and the leachate fluxes were strongly increased after D/W. The increase of solute P was less for beech than for spruce coinciding with less actual rewetting of the beech forest floor. Leaching of total N from the spruce forest floor was not affected by D/W, however, concentrations and leaching of NH4 increased, while leaching of NO3 decreased. For beech the leaching of total N and NH4 increased after D/W, while NO3 leaching decreased. The results indicate that also under realistic conditions, D/W of forest floors increases solute P and leads to changes in the ratio of NH4/NO3 in solution, thereby altering the availability of the nutrients. [ABSTRACT FROM AUTHOR]

In the context of FTIR ATR-based sensors, the organic layer covering the ATR element has to be as stable as possible for optimal spectroscopic measurements. Previously, this self-assembled covering was considered stable after several hours under a PBS flux, probably due to a hydrophobic barrier, which prevents water penetration into the grafted network. Stability and reactivity, measured simultaneously using FTIR ATR, identify the limits of the previously used molecular construction. For the first time, surface etching of the previous functionalised Ge devices (Ge-PEG-NHS), a few minutes after BSA injection, was observed. It was concluded that the molecular chain deformation of Ge-PEG-NHS likely occurred when large molecules were bound. BSA loaded onto a Ge-PEG-NHS surface led to network deprotection, with the probable disruption of hydrogen bonds for single barrier-based networks. This, in turn, was presumably influenced by the random deposition of the NHS moiety on the PEG chain. A new functionalised germanium device, using a rapid three-step in situ procedure, provides an efficient robust network composed of two protective barriers, ideal for the binding of various sized molecules. The Ge-APS-PEG-NHS device has shown exceptional sensitivity with regards to BSA and ethanolamine target molecules while offering homogeneous NHS distribution. [ABSTRACT FROM AUTHOR]

Previous researches demonstrated the occurrence of unique in-sewer sediment, the organic layer, on the Marais site in Paris, capable of explaining the entire wet weather sewer production of suspended particles. Other studies on sites having no similar organic sediment, Clichy in Paris and Ecully in Lyon, demonstrated a wet weather sewer deposits contribution (SDC) to effluent pollution comparable to that of the Marais site, casting therefore doubts on the implication of the organic layer to the outlet discharge pollution. So, an in-depth comparative investigation of the different sites' mean SDC was carried out to confirm or refute the major role of this layer vis-à-vis sewer production. The size and characteristics of the events' sample used to calculate the SDC were analyzed to find whether a statistical bias may have masked a difference that would be more coherent with field observations. After homogenizing these elements, the organic layer regained some of its previously alleged participation in sewer contribution (a maximum of 36% of the total SDC) but another unknown source was still dominant. This suggests that sewer sediment production during wet weather is a result of multiple sediment erosion: the organic layer and another major source not yet identified. [ABSTRACT FROM AUTHOR]

Forest floor carbon stocks, which include different components of litter, hemic and sapric materials, have not been empirically quantified in tropical montane forest, although they influence soil carbon (C) pools. To date, the contribution of arbuscular mycorrhizae in C sequestration potentials in tropical montane forests have not been clearly investigated. This study determined the amount of C stocks in the different decomposing layers of forest floor, mainly litter, hemic and sapric materials. The abundance of arbuscular mycorrhizal root colonisation differed among forest floor fractions. Forest floor was measured for depth, area density, dry mass and carbon fraction separately in Sungai Kial Forest Reserve, Pahang, Malaysia to calculate C stocks. Percentages of root colonisation in the hemic and sapric materials were investigated. The results showed that forest floor C stocks were significantly higher in hemic (5 Mg C ha−1) and sapric (7.7 Mg C ha−1) compared with the litter fragments (1.5 Mg C ha−1). Mycorrhizal root colonisation was significantly higher (75%) in the toeslope compared with the summit area in the hemic materials. Segregation of forest floor layers provided greater accuracy in forest floor C stocks reporting. [ABSTRACT FROM AUTHOR]

Chronosequences can provide valuable insights into carbon (C) and nitrogen (N) dynamics across natural gradients with C and N stable isotopes serving as powerful tool investigating these dynamics. We studied changes in δC and δN values in litter, organic layer and mineral soil on dunes across the Haast chronosequence (New Zealand), which spans 120 to 2870 years of pedogenesis beneath a temperate rainforest. Decomposition was approximated from linear regression slopes between C concentrations and δC values and termed beta. Similarly we calculated beta values to test the relationship between vertical N decrease and δN increase. Decreasing δC values of litter with age suggests a physiological response of plants to decreased litter N concentrations. A decrease of litter δN in the early succession stages and a second decline after 1300 years indicates reduced N fixation. Beta values increased during early ecosystem development and at old sites, and were lowest at the intermediate stages (1500 years), which suggests decomposition did not decrease constantly with time. Beta values were lowest at the youngest site and increased within the first 200 years, likely because litter as the uppermost part of the vertical depth profile reflected an increased supply of N depleted in N provided by fungi. We found relations between beta and beta values suggesting that there might be shared processes shaping δC and δN vertical depth profiles, e.g. microbial cycling, transport or sorption. [ABSTRACT FROM AUTHOR]

The article presents a study aimed to evaluate the imports and exports of dissolved nitrogen from mull-type organic layers to identify control techniques of nitrogen (N) leaching among beech forests in Central Europe. The study is conducted through the continuous measurement of dissolved N fluxes with throughfall and through mull-type organic layers. The results of the study indicate that dissolved N exports from organic layers contain significan amount of throughfall-derived N.

A process-based model for 137 Cs transfer in forest surface environments was developed to assess the dynamic behavior of Fukushima-derived 137 Cs in a Japanese forest. The model simulation successfully reproduced the observed data from 3 year migration of 137 Cs in the organic and mineral soil layers at a contaminated forest near Fukushima. The migration of 137 Cs from the organic layer to the mineral soil was explained by the direct deposition pattern on the forest floor and the turnover of litter materials in the organic layer under certain ecological conditions. Long-term predictions indicated that more than 90% of the deposited 137 Cs would remain within the top 5 cm of the soil for up to 30 years after the accident, suggesting that the forest acts as an effective long-term reservoir of 137 Cs with limited transfer via the groundwater pathway. The model was also used to explore the potential impacts of soil organic matter (SOM) interactions on the mobility and bioavailability of 137 Cs in the soil–plant system. The simulation results for hypothetical organic soils with modified parameters of 137 Cs turnover revealed that the SOM-induced reduction of 137 Cs adsorption elevates the fraction of dissolved 137 Cs in the soil solution, thereby increasing the soil-to-plant transfer of 137 Cs without substantially altering the fractional distribution of 137 Cs in the soil. Slower fixation of 137 Cs on the flayed edge site of clay minerals and enhanced mobilization of the clay-fixed 137 Cs in organic-rich soils also appeared to elevate the soil-to-plant transfer of 137 Cs by increasing the fraction of the soil-adsorbed (exchangeable) 137 Cs. A substantial proportion (approximate 30%–60%) of 137 Cs in these organic-rich soils was transferred to layers deeper than 5 cm decades later. These results suggested that SOM influences the behavior of 137 Cs in forests over a prolonged period through alterations of adsorption and fixation in the soil. [ABSTRACT FROM AUTHOR]

The current density-voltage (J-V) characteristics of an organic layer sandwiched between two electrodes were simulated by using the space-charge-limited current (SCLC) model and the trap-assisted tunneling (TAT) model taking into account the leakage current paths. The experimental J-V curves of the Al/Alq 3 /indium-tin-oxide (ITO) and the Al/mCP/ITO devices fabricated by thermal evaporation were in reasonable agreement with the simulated results calculated by the SCLC and TAT models. The tunneling process in an organic layer was significantly related to the nature traps of disordered organic semiconductors. The leakage current of an organic layer was dominantly attributed to the TAT mechanism. [ABSTRACT FROM AUTHOR]