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Diatom biosilica are highly complex inorganic/organic hybrid materials. To get deeper insights on their structure at a molecular level, model systems that mimic the complex natural compounds were synthesized and characterized. A simple and efficient peptide immobilization strategy was developed, which uses a well‐ordered porous silica material as a support and commercially available Fmoc‐amino acids, similar to the known solid‐phase peptide synthesis. As an example, Fmoc‐glycine and Fmoc‐phenylalanine are immobilized on the silica support. The success of functionalization was investigated by 13C CP MAS and 29Si CP MAS solid‐state NMR. Thermogravimetric analysis (TGA) and elemental analysis (EA) were performed to quantify the functionalization. Changes of the specific surface area, pore volume, and pore diameters in all modification steps were studied by Brunauer–Emmett–Teller based nitrogen adsorption–desorption measurements (BET). The combination of the analytical methods provided high grafting densities of 2.1±0.2 molecules/nm2 on the surface. Furthermore, they allowed for monitoring chemical changes on the pore surface and changes of the pore properties of the material during the different functionalization steps. This universal approach is suitable for the selective synthesis of pores with tunable surface‐peptide functionalization, with applications to the synthesis of a big variety of silica–peptide model systems, which in the future may lead to a deeper understanding of complex biological systems. A protocol for direct solid‐phase peptide synthesis inside silica pores has been developed and its success and efficacy monitored by solid‐state NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Micropores of shale are significant to the gas content and production potential of shale, which has been verified in the research of marine shale gas; while, few studies have been conducted on lacustrine shales. This study collected 42 samples from three wells in the Late Cretaceous Qingshankou Formation of the southern Songliao Basin, NE China, and investigated these samples by the focused ion beam‐scanning electron microscope (FIB–SEM) and nitrogen adsorption analysis techniques. Four types of micropores were identified in the samples, i.e., intergranular pore, intracellular pore, organic matter pore and microfracture. The pore structure type is characterized by open slit pores and "ink type" pores which are mainly 1.5–5 nm in diameter with mesopores as the main pores. The mesopores account for 74.01% of the pore volume and 54.68% of the pore surface area. Compared with the lacustrine shales from the Triassic Yanchang Formation in the Ordos Basin and Xujiahe Formation in the Sichuan Basin, the intergranular clay mineral interlayer pores are considered to be the main reservoir space for shale gas storage in the study area, followed by intraparticle pores, organic matter pores and microfractures. Maturity and micropore are the key controlling factors which affect the shale gas content of the Qingshankou Formation in southern Songliao Basin. [ABSTRACT FROM AUTHOR]

Abstract: Increases in nitrogen (N) deposition and variation in precipitation have been occurring in temperate deserts; however, little information is available regarding plant phenological responses to environmental cues and their relationships with plant growth pattern in desert ecosystems. In this study, plant phenology and growth of six annuals in response to N and water addition were monitored throughout two consecutive growing seasons in 2011 and 2012 in a temperate desert in northwestern China. The effects of N and water addition on reproductive phenology differed among plant species. N and water addition consistently advanced the flowering onset time and fruiting time of four spring ephemerals; however, their effects on two spring‐summer annuals were inconsistent, with advances being noted in one species and delays in another. N and water addition alone increased plant height, relative growth rate, leaf number, flower number, and individual biomass, while their combinative effects on plant growth and reproductive phenology were dependent on species. Multiple regression analysis showed that flowering onset time was negatively correlated with relative growth rate of two species, and negatively correlated with maximum plant height of the other four species. Our study demonstrates that phenological responses to increasing precipitation and N deposition varied in annuals with different life histories, whereby the effects of climate change on plant growth rate were related to reproductive phenology. Desert annuals that were able to accelerate growth rate under increasing soil resource availability tended to advance their flowering onset time to escape drought later in the growing season. This study promotes our understanding of the responses of temperate desert annuals to increasing precipitation and N deposition in this desert. [ABSTRACT FROM AUTHOR]

Nutrient supplies to plants from ants are well known from specialised myrmecophytic symbioses and from plants growing in soil close to ant nests. However, above-ground nutrient pathways may play a largely unrecognised role also in less specialised ant-plant interactions-the numerous facultative relationships, where ants forage on plants., In a laboratory experiment, weaver ants ( Oecophylla smaragdina) were confined to the canopies of coffee ( Coffea arabica) seedlings, excluding any ant-to-plant transfer of nutrients via the soil strata. When ants were fed 15N-labelled glycine and subsequently deposited faecal droplets on the seedlings, coffee leaves showed increased levels of 15N and total nitrogen compared to control plants without ants. This was evident for both exposed leaves and leaves covered in plastic bags (i.e. not directly exposed to ants). Thus, nitrogen from ant excretions was absorbed through the coffee leaves, and subsequently, translocated within the plants and possibly leading to the observed higher shoot/root (wet weight) ratios observed on ant-plants compared to controls., Synthesis. These results reveal an undescribed foliar uptake of ant-provided nutrients. If this is a general mechanism, a vast amount of ant-plant interactions involves fertilisation. Foliar fertilisation by ants may be an important steady benefit to plants, which has driven the evolution of ant-plant mutualisms in parallel with the well-recognised but probably more fluctuating benefit from herbivore protection. Given the world-wide abundance of plant canopies foraged by ants, this nutrient pathway may be of high ecological significance. [ABSTRACT FROM AUTHOR]

Nitrogen adsorption-desorption for mesopore characterization requires the using of expensive instrumentation, time-consuming processes, and the consumption of liquid nitrogen. Herein, a new method is developed to measure the pore parameters through mixing a mesoporous substance with a supersaturated SiO2 colloidal solution at different temperatures, and subsequent rapid measurement of reflection changes of the precipitated liquid photonic crystals. The pore volumes and diameters of mesoporous silica were measured according to the positive correlation between unit mass reflection change (Δ λ/m) and pore volume ( V), and the negative correlation between average absorption temperature ( T) and pore diameter ( D). This new approach may provide an alternative method for fast, convenient and economical characterization of mesoporous materials. [ABSTRACT FROM AUTHOR]

BACKGROUND Fine-tuning production inputs such as seeding rate, nitrogen (N), and genotype may improve end-use quality of hard red winter wheat ( Triticum aestivium L.) when growing conditions are unpredictable. Studies were conducted at the Agronomy Research Farm ( ARF; Lincoln, NE, USA) and the High Plains Agricultural Laboratory ( HPAL; Sidney, NE, USA) in 2014 and 2015 in Nebraska, USA, to determine the effects of genotype (6), environment (4), seeding rate (3), and flag leaf top-dressed N (0 and 34 kg N ha−1) on the end-use quality of winter wheat. RESULTS End-use quality traits were influenced by environment, genotype, seeding rate, top-dressed N, and their interactions. Mixograph parameters had a strong correlation with grain volume weight and flour yield. Doubling the recommended seeding rate and N at the flag leaf stage increased grain protein content by 8.1% in 2014 and 1.5% in 2015 at ARF and 4.2% in 2014 and 8.4% in 2015 at HPAL. CONCLUSION The key finding of this research is that increasing seeding rates up to double the current recommendations with N at the flag leaf stage improved most of the end-use quality traits. This will have a significant effect on the premium for protein a farmer could receive when marketing wheat. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

We aim to develop novel photoresponsive surface molecularly imprinted polymer (SIMP) microspheres, an SiO2-SIMP, for the photocontrolled extraction of uric acid from biological samples. The SiO2-SMIP was prepared on silica microspheres by surface polymerization and characterized by using scanning electron microscopy, transmission electron microscopy, FTIR spectroscopy, thermogravimetric analysis, nitrogen adsorption-desorption analysis, and UV-visible spectroscopy. The SiO2-SMIP microspheres showed a photocontrolled uptake and release of uric acid in NaH2PO4 buffer upon alternate irradiation at 365 and 440 nm. The SiO2-SMIP microspheres were able to photocontrollably extract uric acid from complicated biological samples for concentration analysis with no significant interference encountered and it exhibited very good recognition ability and fast binding kinetics toward uric acid. [ABSTRACT FROM AUTHOR]

Based on the first-principles of density-functional theory (DFT), the effects of NO2, NO, and NH3 adsorption on the change in geometric stability, adsorption properties, and electronic structures of B- or N-doped graphene are investigated. For NO/NO2-B/N-doped graphene systems, NO/NO2 have more stability on B-doped graphenes than them on N-doped graphenes. The introduction of B atom can make the adsorption of NO/NO2 on graphene much easier. The stable configuration of B-doped graphene is more likely to be gas sensor for detecting toxic gases such as NO2 and NO. This makes it possible to use B-doped graphene as sensing materials for designing novel gas sensors. The interaction between NH3 and B/N-doped graphene is rather weak. The results will provide a new direction for the adsorbed NO2, NO, and NH3 on graphene by introducing B/N doping atoms into graphene. [ABSTRACT FROM AUTHOR]

A robust hydrogen-bonded organic framework HOF-TCBP (H4TCBP=3,3′,5,5′-tetrakis-(4-carboxyphenyl)-1,1′-biphenyl) has been successfully constructed and structurally characterized. It possesses a permanent 3D porous structure with a 5-fold interpenetrated dia topological network. This activated HOF-TCBP has a high BET surface area of 2066 m2 g−1 and is capable of highly selective adsorption and separation of light hydrocarbons under ambient conditions. It shows excellent thermal stability, as demonstrated by PXRD experiments and N2 adsorption tests. Practical use of HOF-TCBP is facilitated by the ease of its preparation and renewal through rotary evaporation. [ABSTRACT FROM AUTHOR]

We investigated photoinhibition on natural communities of ammonia oxidizing (AO) archaea (AOA) and bacteria (AOB) embedded in complex stream biofilms, and its implications on nitrogen uptake at biofilm scale. Based on the strong photoinhibition previously exhibited by free living and cultured AOA and AOB, we expected AO activity to decrease in biofilms experimentally exposed to light, reducing the contribution of microbial nitrification to ammonium uptake. To test it, we conducted light manipulation experiments in mesocosms using biofilms naturally developed on stream cobbles sides both exposed to light (light-side) and facing the sediment (dark-side). We observed a strong AO photoinhibition in dark-side biofilms, accompanied by either biofilm-scale decreases in nitrification or increases in nitrogen uptake likely by heterotrophic activity. Conversely, in light-side biofilms photoinhibition was not observed suggesting that photoautotrophic layers may protect AO in situ by a sunshade effect. Experimental light and dark alternation cycles stimulated AO, enhancing both nitrification and ammonium uptake. These results support photoinhibition effects on natural AO communities, especially in biofilms developed under ambient dark conditions, whereas this effect seems to be buffered in biofilms developed under light conditions. Therefore, the contribution of nitrification to ammonium uptake at biofilm scale should consider not only the physiological study of AOA and AOB, but also the environmental conditions and community structure at the habitat microscale, since they may counterbalance, among others, the damaging light effects under natural conditions. [ABSTRACT FROM AUTHOR]

We conducted a study that shows that light and dark conditions do not affect the uptake rates of ammonium and nitrate by the seagrass Zostera noltei. This is an important advantage over some seaweed species in which these rates are severely reduced at night. In the light, the ammonium uptake rates were initially higher (15 and 20 μmol·g−1·h−1) and stabilized at a rate of 5 μmol·g−1·h−1 after 1 h, whereas in the dark the rates remained constant at a rate of 10 μmol·g−1·h−1 over the first 180 min of incubation. The rates of nitrate uptake in the light were high within the first 120 min of incubation (7.2-11.1 μmol·g−1·h−1) and decreased afterwards to lower values (0.8-3.9 μmol·g−1·h−1), whereas in the dark the rates fluctuated around 0.0-11.1 μmol·g−1·h−1 throughout the whole incubation time (7 h). The soluble sugar content of Z. noltei leaves increased significantly with both ammonium and nitrate incubations in the light, indicating the metabolic outcome of photosynthesis. In the dark, there was no significant variation in either the soluble sugar or in the starch content of leaves, rhizomes or roots in either the ammonium or nitrate incubations. However, the total starch content of plants decreased at night whereas the total soluble sugars increased, suggesting a process of starch catabolism to generate energy with the consequent production of smaller monosaccharide products. The starch content of rhizomes decreased significantly during the light incubations with nitrate but not with ammonium. These results suggest that carbohydrate mobilization is necessary for Z. noltei to account for extra energetic costs needed for the uptake and assimilation of nitrate. Furthermore, our results suggest that nitrate uptake, at least during the day, requires the mobilization of starch whereas the uptake of ammonium does not. [ABSTRACT FROM AUTHOR]

Landscaping paradigms that encourage high-input, intensively managed and mono-culture turf/lawn landscapes have raised concerns about water quality. We conducted a watershed-scale assessment of landscaping practices that included turf, urban, forest, native meadow, and mixed landuse watersheds with a professional golf course and a parking lot. The turf site was moderately managed and had lower fertilizer inputs than those typically used by homeowners and golf courses. Stream water sampling was performed during base flow and storm events. Highest nitrate and total nitrogen concentrations in runoff were observed for the mixed watershed draining the golf course. In contrast, concentrations in base flow from the turf watershed were lower than expected and were comparable to those measured in the surrounding meadow and forest sites. Total nitrogen concentrations from the turf site increased sharply during the first storms following fertilization, suggesting that despite optimal management there exists a risk for nutrient runoff following fertilization. Overall, this study suggests that turf or lawns, when managed properly, pose minimal water quality risk to surface waters. Rate, timing of application, and the type of fertilizer appear to be the key factors affecting water quality. Better education of homeowners and landscaping professionals with regard to these factors may be a cost-effective strategy to reduce nonpoint source pollution. [ABSTRACT FROM AUTHOR]

In this study the results of the characterization of hierarchical silica-gel samples with nitrogen adsorption and positron annihilation lifetime spectroscopy (PALS) were compared. The hierarchical silica-gel samples were synthesized by pseudomorphic transformation of a meso porous silica gel with CTAOH. The results of the PALS measurements clearly indicate the hierarchical pore structure of the materials. Two individual pore systems can be detected with a good resolution. The peak area of the signals can be calculated and compared with the pore volumes determined by nitrogen adsorption. [ABSTRACT FROM AUTHOR]

We prepared core-shell polymer-silsesquioxane hybrid microcapsules from cage-like methacryloxypropyl silsesquioxanes (CMSQs) and styrene (St). The presence of CMSQ can moderately reduce the interfacial tension between St and water and help to emulsify the monomer prior to polymerization. Dynamic light scattering (DLS) and TEM analysis demonstrated that uniform core-shell latex particles were achieved. The polymer latex particles were subsequently transformed into well-defined hollow nanospheres by removing the polystyrene (PS) core with 1:1 ethanol/cyclohexane. High-resolution TEM and nitrogen adsorption-desorption analysis showed that the final nanospheres possessed hollow cavities and had porous shells; the pore size was approximately 2-3 nm. The nanospheres exhibited large surface areas (up to 486 m2 g−1) and preferential adsorption, and they demonstrated the highest reported methylene blue adsorption capacity (95.1 mg g−1). Moreover, the uniform distribution of the methacryloyl moiety on the hollow nanospheres endowed them with more potential properties. These results could provide a new benchmark for preparing hollow microspheres by a facile one-step template-free method for various applications. [ABSTRACT FROM AUTHOR]

Further development of the chemistry and applications of chiral compounds that possess configurationally stable stereogenic nitrogen atoms is hampered by the lack of efficient strategies to access such compounds in an enantiomerically pure form. Esters of propiolic acid and chiral alcohols were evaluated as cheap and readily available Michael acceptors in a diastereoselective synthesis of N-stereogenic compounds by means of a double aza-Michael conjugate addition. Diastereomeric ratios of up to 74:26 and high yields were achieved with (–)-menthyl propiolate as a substrate. Furthermore, a detailed mechanistic investigation was undertaken to shed some light on the course of this domino transformation. Kinetic studies revealed that the protic-solvent additive acts as a Brønsted acid and activates the ester toward the initial attack of the tetrahydrodiazocine partner. Conversely, acidic conditions proved unfavorable during the final cyclization step that provides the product. [ABSTRACT FROM AUTHOR]

The rusts of different kinds of weathering steels and mild steel formed by CCT and exposure to a coastal atmosphere were examined by the adsorption of nitrogen and water molecules. The specific surface area (S) of the rusts was determined from the adsorption isotherms. The rusts of the weathering steels showed higher S and smaller particle size than those of the mild steel, indicating that the weathering steels form more compact rust layers compared to the mild steel. The S of the rusts formed at different positions of a simulated girder located in the coast strongly depended on the setting position. [ABSTRACT FROM AUTHOR]

Adsorption behaviors of nitrogen and CO2 on Norit R1 Extra and AlO(OH) nanoparticles and hollow spheres were measured under different temperature and pressure conditions using a magnetic suspension balance. Independent from the substrate investigated, all isotherms increase at lower pressure, reach a maximum, and then decrease with increasing pressure. In addition, selected experimental data were correlated with different model approaches and compared with reliable literature data. In case of CO2 on AlO(OH), capillary condensation was observed at two defined temperatures. The results suggest that the conversion of the liquid into a supercritical adsorbate phase does not take place suddenly. [ABSTRACT FROM AUTHOR]

A key part of the uncertainty in terrestrial feedbacks on climate change is related to how and to what extent nitrogen (N) availability constrains the stimulation of terrestrial productivity by elevated CO2 ( eCO2), and whether or not this constraint will become stronger over time. We explored the ecosystem-scale relationship between responses of plant productivity and N acquisition to eCO2 in free-air CO2 enrichment ( FACE) experiments in grassland, cropland and forest ecosystems and found that: (i) in all three ecosystem types, this relationship was positive, linear and strong ( r2 = 0.68), but exhibited a negative intercept such that plant N acquisition was decreased by 10% when eCO2 caused neutral or modest changes in productivity. As the ecosystems were markedly N limited, plants with minimal productivity responses to eCO2 likely acquired less N than ambient CO2-grown counterparts because access was decreased, and not because demand was lower. (ii) Plant N concentration was lower under eCO2, and this decrease was independent of the presence or magnitude of eCO2-induced productivity enhancement, refuting the long-held hypothesis that this effect results from growth dilution. (iii) Effects of eCO2 on productivity and N acquisition did not diminish over time, while the typical eCO2-induced decrease in plant N concentration did. Our results suggest that, at the decennial timescale covered by FACE studies, N limitation of eCO2-induced terrestrial productivity enhancement is associated with negative effects of eCO2 on plant N acquisition rather than with growth dilution of plant N or processes leading to progressive N limitation. [ABSTRACT FROM AUTHOR]

Highly dispersed MoO3 on SiMCM-41 was applied to the dehydration of 2-butanol. MoO3 / MCM-41 catalysts were prepared using a modified atomic layer deposition method. The structural characteristics of MoO3 supported on SiMCM-41 were examined by inductively coupled plasma spectrometry, nitrogen adsorption, X-ray photoelectron spectroscopy, and X-ray diffraction. The textural characteristics of SiMCM-41 were retained after loading with MoO3 . Ammonia temperature-programmed desorption and Fourier transformation infrared spectroscopy of adsorbed pyridine showed that Lewis acid sites were formed on the MoO3 / MCM-41 catalysts. Among the MoO3 / MCM-41 catalysts, the MoO3 (16.4 wt %)/ MCM-41 catalyst showed the highest catalytic activity for butene synthesis from 2-butanol dehydration due to the largest number of acid sites. [ABSTRACT FROM AUTHOR]

Nitrogen sorption and small- and wide-angle X-ray and neutron scattering techniques were used to study the porous structure of geopolymers, inorganic polymers synthesized by reaction of a strongly alkaline solution and an aluminosilicate source (metakaolin). The effects of aging and the use of alkali activators (Na+, K+) of different sizes were investigated at room temperature. The influence of aging time on the microstructure of both geopolymer matrixes was verified in terms of pore volume and specific surface area. The results suggested a refinement of the porosity and therefore a reduction in the pore volume over time. Regardless of the age considered, some characteristics of the porous network such as pore size, shape and distribution depend on the alkali activator used. Whatever the technique considered, the potassium geopolymer has a greater specific surface area than the sodium geopolymer. According to the scattering results, the refinement of the porosity can be associated with, first, a densification of the solid network and, secondly, a partial closure of the porosity at the nanometre scale. The kinetics are much slower for the sodium geopolymer than for the potassium geopolymer in the six months of observation. [ABSTRACT FROM AUTHOR]

Almost all models of plant resource limitation are grounded in either one or both of two simple conceptual models: Liebig's Minimum Hypothesis (LMH), the idea that plants are limited by the resource in shortest supply, and the Multiple Limitation Hypothesis (MLH), the idea that plants should adjust to their environment so that all essential resources are equally limiting. Despite the differences in their predictions, experiments have so far failed to discriminate between them. In a simple factorial nitrogen and water addition experiment in a Minnesota grassland, we observed shifts in allocation that, as in previous studies, are not all explained by a single theory. We found that leaf biomass responded positively to nitrogen additions but did not respond to water additions. We found that fine-root biomass increased in response to water additions, but only at low nitrogen levels, and that fine-root biomass decreased in response to nitrogen additions, but only at high water levels. To understand these responses we built a physiologically based model of plant competition for water, nitrogen, and space to predict plant allocation to fine roots and leaves. Critically, we include in our model the inherent variability of soil moisture and treat light, water, and nitrogen as resources with distinct mechanistic roles. Experimental results showed that plants were nitrogen and water limited. The model explains the experimental results, under conditions of co-limitation, as follows. Foliage increases with nitrogen additions but not water additions because leaf construction is constrained by nitrogen uptake. When water is added, plants spend a larger fraction of the growing season limited by light (and effectively nitrogen) than by water. Thus, water additions cause fine-root biomass to increase because of the increased importance of nitrogen limitation. The response of fine-root biomass to water additions decreases with nitrogen additions because these additions reduce nitrogen limitation. In general, our results are explained by sequential resource limitation. The rate of carbon assimilation may be limited by a single resource at any one moment, but the identity of the limiting resource(s) changes throughout the growing season. [ABSTRACT FROM AUTHOR]

A disposable iron-based catalyst, red mud, was modified by different dissolution-precipitation methods. The catalysts obtained were characterized by nitrogen adsorption, X-ray diffraction, scanning electron microscopy, and ammonia temperature-programmed desorption. They were tested for slurry-phase hydrocracking of vacuum residue in a batch reactor. The red-mud catalyst activated by phosphoric acid showed the highest catalytic activity since the activation by phosphoric acid resulted in the decrease in particle size which facilitated the transformation of red mud to the active sulfide form in the reaction. [ABSTRACT FROM AUTHOR]

ABSTRACT Nitrogen species distribution during coal pyrolysis with Ca addition in N2, CO2 and Ar was studied at 1000 °C using a horizontal tube furnace. In particular, the effect of Ca on the distribution of nitrogen species in N2 and CO2 atmospheres, which were closer to pyrolysis processes of conversional air and oxy-fuel combustion in comparison with inert Ar environment, was investigated for the first time in this work. It was found that Ca has a great effect on nitrogen species distribution during both coal and demineralized coal pyrolysis; on the other hand, CO2 causes the formation of NO. Demineralization increases the formation of HCN and char nitrogen, but there is little effect on NH3 formation during pyrolysis in N2, in contrast to pyrolysis in Ar atmosphere, which decreases NH3 formation. A significant reduction in char yield was found after char gasification in CO2 at 1000 °C. With two different Ca-based additives, i.e., (CH3COO)2Ca and Ca(OH)2, char yield decreases with the increasing amount of Ca additives in both cases. The effect of Ca on HCN and NH3 formation during pyrolysis depends on both the form of Ca and the amount of addition. In most cases, HCN and NH3 formation decreases with Ca addition in Ar, but increases in N2. Ca addition slightly promotes HCN formation during pyrolysis in CO2. There is no NH3 detected during pyrolysis in CO2 because of the reaction of NH3 and CO2 in the background. In addition, NO concentration decreases sharply with increasing the amount of Ca addition in the atmosphere of CO2, which means that Ca has an effect not only on pyrolysis, but also on gasification of char in CO2. In most cases, char nitrogen increases with Ca addition in N2 or Ar. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Foliar N fertilization often makes up a major portion of the total N inputs applied to creeping bentgrass (Agrostis stolonifera L.) golf greens. Many such applications are made using fertilizers that have been formulated and marketed as specialty foliar fertilizers. Various forms of inorganic and organic N are included in these specialty products. However, little is currently known about the foliar absorption efficiency among different chemical N forms routinely applied to putting greens. This project was conducted to evaluate the foliar uptake of N from several 15N-labeled inorganic and organic sources. Three common N fertilizer forms {urea (NH2CONH2), ammonium sulfate [(NH4)2SO4], and potassium nitrate (KNO3)} were used in the trial along with three amino acids (glycine, l-glutamic acid, and l-proline). All treatments were applied at a rate of 0.5 g N m-2 on 18 Sept. 2008, 14 Oct. 2008, and 24 June 2010 to plots within a 'Penn G2' creeping bentgrass research green. Plant tissue samples were taken 1 and 8 h after application for N analysis. Foliar uptake of the various N compounds ranged from 31 to 56% of the N applied at the final sampling time of 8 h after application. Nitrogen source had a significant effect on the amount of N fertilizer recovered within plant leaves and shoots. Foliar absorption of KNO3 into aerial plant parts was lower than most of the chemical forms tested while most of the compounds supplied N to the plant in similar proportions. [ABSTRACT FROM AUTHOR]

Monodispersed mesoporous silica spheres ( MMSSs) with tunable particle size were successfully synthesized from tetraethyl orthosilicate ( TEOS) and cetyltrimethylammonium bromide ( CTAB) under an alkaline condition. The MMSSs synthesized under different reaction conditions, such as reaction temperature, co-solvent amount, and TEOS and CTAB concentrations, have been investigated by scanning electron microscopy ( SEM), transmission electron microscopy ( TEM), small angle X-ray diffraction ( SAXRD), and nitrogen adsorption-desorption. The average particle size increases with increase in the reaction temperature from 40°C to 90°C, and 80°C is the optimal temperature to synthesize MMSSs with narrow particle size of 75 ± 14 nm. Ethanol plays a role as co-surfactant in low concentration, and then as co-surfactant and co-solvent in high concentration, which results in an increase in particle size from 75 ± 14 nm to 518 ± 30 nm and change of the mesoporous structure from paralleled array type to radially orientated type. The average particle size and yield of MMSSs increase with increase in the TEOS concentration when the TEOS concentration reaches saturated level ( Cs = 0.09 M), but some small silica particles appear when the TEOS concentration is higher than the critical level ( Cs* = 0.134 M). When the CTAB concentration increases, at the same TEOS concentration, the surface area, and pore volume increases, but the monodispersity becomes low. [ABSTRACT FROM AUTHOR]

The results of small-angle and ultra-small-angle X-ray scattering on porous CaCO3 microparticles of pulverulent vaterite made by a conventional chemical route and by using supercritical CO2 are presented. The scattering curves are analysed in the framework of the Guinier-Porod model, which gives the radii of gyration of the scattering objects and their fractal dimension. In addition, the porosity and the specific surface area are determined by using the Porod invariant, which is modified to take into account the effective thickness of the pellet. The results of this analysis are compared with those obtained by nitrogen adsorption. [ABSTRACT FROM AUTHOR]

Surface energy of cerium oxide was measured by differential scanning calorimetry ( DSC). Nanocrystalline CeO2 samples were synthesized by a nonaqueous sol-gel method and their surface and interfacial areas were determined from nitrogen adsorption, X-ray diffraction, and electron microscopy measurements. Three samples were repeatedly heated in a differential scanning calorimeter and the excess enthalpy was obtained from the difference in DSC traces between first heating, during which coarsening occurred, and second heating. Surface enthalpy was calculated from excess enthalpy and from changes in surface and interfacial areas. The measured surface enthalpy for CeO2, 1.2 ± 0.2 J/m2, is consistent with values from oxide melt solution calorimetry on samples with different surface areas. This is the first successful measurement of surface energy using scanning calorimetry. [ABSTRACT FROM AUTHOR]

The perturbation of the global nitrogen (N) cycle due to the increase in N deposition over the last 150 years will likely have important effects on carbon (C) cycling, particularly via impacts on forest C sequestration. To investigate this effect, and the relative importance of different mechanisms involved, we used the Generic Decomposition And Yield (G'DAY) forest C–N cycling model, introducing some new assumptions which focus on N deposition. Specifically, we (i) considered the effect of forest management, (ii) assumed that belowground C allocation was a function of net primary production, (iii) assumed that foliar litterfall and specific leaf area were functions of leaf N concentration, (iv) assumed that forest canopies can directly take up N, and (v) modified the model such that leaching occurred only for nitrate N. We applied the model with and without each of these modifications to estimate forest C sequestration for different N deposition levels. Our analysis showed that N deposition can have a large effect on forest C storage at ecosystem level. Assumptions (i), (ii) and (iv) were the most important, each giving rise to a markedly higher level of forest C sequestration than in their absence. On the contrary assumptions (iii) and (v) had a negligible effect on simulated net ecosystem production (NEP). With all five model modifications in place, we estimated that the C storage capacity of a generic European forest ecosystem was at most 121 kg C kg−1 N deposited. This estimate is four times higher than that obtained with the original version of G'DAY (27.8 kg C kg−1 N). Thus, depending on model assumptions, the G'DAY ecosystem model can reproduce the range of dC : dNdep values found in the literature. We conclude that effects of historic N deposition must be taken into account when estimating the C storage capacity of a forest ecosystem. [ABSTRACT FROM AUTHOR]

A green house experiment was designed to test the idea that competition for inorganic nitrogen (N) between plants and heterotrophic microorganisms occurs in soils with high C:N ratios, qualifying for N limited microbial activity, but not at low C:N ratios. The short-term (24 h) 15N uptake by the grass Festuca gigantea and microorganisms in planted and unplanted soils was determined, and the bacterial activity was measured by the 3H-thymidine incorporation technique. Two deciduous forest soils, with C:N-ratios of 20 and 31, and the 20 soil amended with litter to a C:N ratio of 34, were used. A novel and important part of the experimental design was the preparation of the unplanted reference soil with plants present until the competition assay started by the addition of 15N labelled ammonium ( ) or nitrate ). The results suggested that plants and soil microorganisms competed for mineral N but under influence of other factors than the soil C:N ratio. The plants reduced the microbial uptake of and in the soil with low C:N ratio, which also had the lowest bacterial activity. The plants had a larger N uptake than microorganisms in the two natural soils but smaller in the litter-amended, and their presence enhanced the bacterial activity, especially in the latter soil. The litter-amended soil with its high C:N ratio and easily decomposable C was the soil that best fulfilled the criteria for competition, including a net consumption of mineral N during the assay, the lowest plant uptake of mineral N due to the high N immobilization by microorganisms, and a reduced microbial 15N uptake-to-bacterial activity in the presence of plants. Thus, other factors, such as the decomposability of the soil C and the bacterial activity, were more important than the soil C:N ratio to the outcome of plant–microbial competition for N. [ABSTRACT FROM AUTHOR]

• Here, nitrogen (N) uptake and metabolism, and related gene expression, were analyzed in germinating spores of Glomus intraradices to examine the mechanisms and the regulation of N handling during presymbiotic growth. • The uptake and incorporation of organic and inorganic N sources into free amino acids were analyzed using stable and radioactive isotope labeling followed by high-performance liquid chromatography (HPLC), gas chromatography–mass spectrometry (GC-MS) and liquid scintillation counting and the fungal gene expression was measured by quantitative polymerase chain reaction (Q-PCR). • Quiescent spores store Asp, Ala and Arg and can use these internal N resources during germination. Although not required for presymbiotic growth, exogenous N can also be utilized for the de novo biosynthesis of amino acids. Ammonium and urea are more rapidly assimilated than nitrate and amino acids. Root exudates do not stimulate the uptake and utilization of exogenous ammonium, but the expression of genes encoding a putative glutamate dehydrogenase (GDH), a urease accessory protein (UAP) and an ornithine aminotransferase (OAT) were stimulated by root exudates. The transcript levels of an ammonium transporter (AMT) and a glutamine synthetase (GS) were not affected. • Germinating spores can make effective use of different N sources and the ability to synthesize amino acids does not limit presymbiotic growth of arbuscular mycorrhizal (AM) spores. [ABSTRACT FROM AUTHOR]

In waste materials, proximate analysis measuring the total concentration of carbohydrate, protein, and lipid contents from solid wastes is challenging, as a result of the heterogeneous and solid nature of wastes. This paper presents a new procedure that was developed to estimate such complex chemical composition of the waste using conventional practical measurements, such as chemical oxygen demand (COD) and total organic carbon. The procedure is based on mass balance of macronutrient elements (carbon, hydrogen, nitrogen, oxygen, and phosphorus [CHNOP]) (i.e., elemental continuity), in addition to the balance of COD and charge intensity that are applied in mathematical modeling of biological processes. Knowing the composition of such a complex substrate is crucial to study solid waste anaerobic degradation. The procedure was formulated to generate the detailed input required for the International Water Association (London, United Kingdom) Anaerobic Digestion Model number 1 (IWA-ADM1). The complex particulate composition estimated by the procedure was validated with several types of food wastes and animal manures. To make proximate analysis feasible for validation, the wastes were classified into 19 types to allow accurate extraction and proximate analysis. The estimated carbohydrates, proteins, lipids, and inerts concentrations were highly correlated to the proximate analysis; correlation coefficients were 0.94, 0.88, 0.99, and 0.96, respectively. For most of the wastes, carbohydrate was the highest fraction and was estimated accurately by the procedure over an extended range with high linearity. For wastes that are rich in protein and fiber, the procedure was even more consistent compared with the proximate analysis. The new procedure can be used for waste characterization in solid waste treatment design and optimization. [ABSTRACT FROM AUTHOR]

The phase domain of Ti3O5–Ti2O3–Ti(CO) at 1580 K was determined from the formation energies of Ti(C xO y), as calculated via the Gibbs–Duhem equation. An extensive Ti(CO) domain is attributed to the high affinity between TiC and TiO. The phase domain of Ti3O5–Ti2O3–Ti(CN) was obtained at 1673 K using the formation energies of Ti(C xN y). This study shows that the stable region for Ti2O3 is significantly small in the Ti3O5–Ti2O3–Ti(CN) phase domain. It demonstrates the absence of TiO and Ti2O3 in the normal syntheses of TiC and Ti(CN) from TiO2, respectively. [ABSTRACT FROM AUTHOR]

Nitrogen is required for adequate residue production from cereal cover crops used in notill cotton (Gossypium hirsutum L.) production, but residues can immobilize N needed by cotton. We conducted a 3-yr field study on a Decatur silt loam (clayey, kaolinitic, rhermic Rhodic Paleudulr) in northern Alabama to test N fertilizer practices for cotton grown with a rye (Secale cereale L.) cover crop and conservation tillage. Nitrogen rates applied to the rye cover crop were 0, 34, and 67 kg N ha-1 and cotton N rates were 0, 45, 90, and 135 kg N ha-1. Additionally, 15N microplors were established in cover crop N treatments of 34 kg N ha-1 and in cotton treatments of 90 kg N ha-1. Data collected included cover crop aerial biomass, cover crop C/N ratios, cotton leaf N at first flower, lint yield, lint quality, and 15N in plant and soil samples. Cotton grown in unfertilized rye treatments needed 57 to 60% (38-40 kg N ha-1) more N to maximize yields above median conventional tillage N recommendations (67 kg N ha-1). Cover crop N rates of 67 kg N ha-1 maximized cover crop biomass production for soil protection and soil organic matter aggradation. If the cover crop was fertilized, minimum cotton N applications of 70 and 76 kg N ha-1 were needed for economic optimum and maximum lint yield, respectively. We speculate that cotton N rates may be decreased in the future as new N and C pool equilibria are reached. [ABSTRACT FROM AUTHOR]

Despite their low primary production, ombrotrophic peatlands have a considerable potential to store atmospheric carbon as a result of their extremely low litter decomposition rates. Projected changes in temperature and nitrogen (N) deposition may increase decomposition rates by their positive effects on microbial activity and litter quality, which can be expected to result in enhanced mass loss and N release from Sphagnum and vascular plant litter. This is the first study that examines the combined effects of increased temperature and N deposition on decomposition in bogs. We investigated mass loss and N release at four bog sites along a gradient from north Sweden to northeast Germany in which both temperature and N deposition increased from north to south. We performed two litterbag experiments: one reciprocal experiment with Eriophorum vaginatum litter and one experiment using recalcitrant ( Sphagnum fuscum) and more degradable ( Sphagnum balticum) Sphagnum litter collected from the most northern site. We measured mass loss and N release during two ( Sphagnum) and three ( E. vaginatum) years. The N concentration and decomposability of the E. vaginatum litter did not differ between the sites. Mass loss from E. vaginatum litter increased over the gradient from north to south, but there was no such effect on Sphagnum litter. N loss of all litter types was affected by collection site, incubation site and time and all interactions between these factors. N release in Sphagnum was positively related to N concentration. We conclude that decomposition of vascular plants and Sphagnum litter is influenced by different environmental drivers, with enhanced temperatures stimulating mass loss of vascular plant litter, but not of Sphagnum. Enhanced N deposition increases Sphagnum litter N loss. As long-term consequences of climate change will presumably entail a higher vascular plant production, overall litter decomposition rates are likely to increase, especially in combination with increased temperature. [ABSTRACT FROM AUTHOR]

The effects of increased anthropogenic inputs of reactive nitrogen (N) have been studied at the Harvard Forest Chronic N Experiment, where NH4NO3 has been applied experimentally since 1988 to increase atmospheric deposition rates ∼6- and ∼18-fold above ambient. This paper asks whether conditions favorable to primary production also resulted in plastic increases to flower, fruit, and seedling traits, and focuses primarily on the oaks that dominate the hardwood stands of the Harvard Forest experiment. Litterfall samples collected between 1996 and 2001 revealed that flowers and fruits were significantly more abundant in N-treated plots, and an analysis of oak tree abundance found significant variation both among and within plots. Acorn samples collected during 2003 and 2004 (a mast and a postmast year) were therefore analyzed usingancova models that included an estimate of oak tree abundance. This tree abundance estimate was the only significant driver of increased acorn production during the mast year, and in both years it was a significant factor on plots receiving the highest levels of N. In the postmast year, acorn production was increased in direct response to N-related factors other than tree abundance. Our comparisons of control and N-treated plots for acorn quality traits (e.g. rates of acorn damage, germination percentage, seedling growth) revealed negligible or only transient differences. Shifts in overall acorn abundance – particularly disproportionate N-mediated increases during nonmast years – could have a wide range of ecological consequences beyond the more frequently examined impacts of N deposition on primary production and carbon sequestration. [ABSTRACT FROM AUTHOR]

Response of soil respiration (CO2 emission) to simulated nitrogen (N) deposition in a mature tropical forest in southern China was studied from October 2005 to September 2006. The objective was to test the hypothesis that N addition would reduce soil respiration in N saturated tropical forests. Static chamber and gas chromatography techniques were used to quantify the soil respiration, following four-levels of N treatments (Control, no N addition; Low-N, 5 g N m−2 yr−1; Medium-N, 10 g N m−2 yr−1; and High-N, 15 g N m−2 yr−1 experimental inputs), which had been applied for 26 months before and continued throughout the respiration measurement period. Results showed that soil respiration exhibited a strong seasonal pattern, with the highest rates found in the warm and wet growing season (April–September) and the lowest rates in the dry dormant season (December–February). Soil respiration rates showed a significant positive exponential relationship with soil temperature, whereas soil moisture only affect soil respiration at dry conditions in the dormant season. Annual accumulative soil respiration was 601±30 g CO2-C m−2 yr−1 in the Controls. Annual mean soil respiration rate in the Control, Low-N and Medium-N treatments (69±3, 72±3 and 63±1 mg CO2-C m−2 h−1, respectively) did not differ significantly, whereas it was 14% lower in the High-N treatment (58±3 mg CO2-C m−2 h−1) compared with the Control treatment, also the temperature sensitivity of respiration, Q10 was reduced from 2.6 in the Control with 2.2 in the High-N treatment. The decrease in soil respiration occurred in the warm and wet growing season and were correlated with a decrease in soil microbial activities and in fine root biomass in the N-treated plots. Our results suggest that response of soil respiration to atmospheric N deposition in tropical forests is a decline, but it may vary depending on the rate of N deposition. [ABSTRACT FROM AUTHOR]

When the substituents on the nitrogen of indoles are hydrogen or electron-donating groups, such as methyl [e.g. (I)], benzyl, allyl groups, [2 + 2]-cycloaddition takes place to give the products [e.g. (III)] as (Z)-isomers with excellent yields and enantioselectivities. [ABSTRACT FROM AUTHOR]

A diagram which discusses the efficient synthesis of carbon-nitrogen heterobiaryls through the functionalization of sequential nitrogen and hydrogen.

- None of the well-established nitrogen-related IR absorption bands, common in synthetic and terrestrial diamonds, have been identified in the presolar diamond spectra. In the carbonado diamond spectra, only the single nitrogen impurity (C center) is identified and the assignments of the rest of the nitrogen-related bands are still debated. It is speculated that the unidentified bands in the nitrogen absorption region are not induced by nitrogen, but rather by nitrogen-hydrides because in the interstellar environment, nitrogen reacts with hydrogen and forms NH+; NH; NH2; NH3. Among these hydrides, the electronic configuration of NH+ is the closest to carbon. Thus, this ionized nitrogen-mono-hydride is the best candidate to substitute carbon in the diamond structure. The bands of the substitutional NH+ defect are deduced by redshifting the irradiation-induced N+ bands due to the mass of the additional hydrogen. The six bands of the NH+ defects are identified in both the presolar and the carbonado diamond spectra. The new assignments identify all of the nitrogen-related bands in the spectra, indicating that presolar and carbonado diamonds contain only single nitrogen impurities. [ABSTRACT FROM AUTHOR]