Values Of NH Research Articles

Simulation study on combustion reaction mechanism and heat release rate of ammonia/methane fuels

ABSTRACT Ammonia/methane combustion has the potential to be a viable method for achieving low-carbon combustion. However, further research is required to enhance the combustion mechanism and to gain a deeper understanding of the heat release rate associated with ammonia/methane combustion. A one-dimensional simulation of premixed laminar ammonia/methane flame simulation was carried out based on Okafor ammonia/methane reaction mechanism. The mole fraction of radicals and heat release rate in the ammonia/methane combustion process under different conditions were calculated using CHEMKIN-PRO. The results show that the optimized reaction mechanism was in line with the experimental results in predicting the laminar flame velocity in the fuel-lean zone. The distances between the peak values of NH and heat release rates were small at XNH3 = 0.1 ~ 0.6 and fuel-rich condition. The correlation between NH and the heat release rate was significant, indicating that NH radicals are suitable as markers of the heat release rate in the ammonia/methane flames. The abilities for characterizing heat release rate of [CH][OH], [CH][NO], [NH][OH], [NH][NO], [NH2][OH], and [NH2][NO] were further evaluated. The exponent was added to the radical combination to improve the correlation with heat release rate. [NH]0.88[OH]0.01, [NH]0.92[NO]0.25, [NH2]0.92[OH]0.42, and [NH2]0.97[NO]1.27 correlate well with heat release rates from ammonia/methane flames and they can be used as good markers of heat release rates.

Thermonuclear type-I X-ray bursts and burst oscillations from the eclipsing AMXP swift J1749.4–2807

ABSTRACT Swift J1749.4-2807 is the only known eclipsing accreting millisecond X-ray pulsar. In this paper, we report on seven thermonuclear (Type-I) X-ray bursts observed by NICER during its 2021 outburst. The first six bursts show slow rises and long decays, indicative of mixed H/He fuel, whereas the last burst shows fast rise and decay, suggesting He-rich fuel. Time-resolved spectroscopy of the bursts revealed typical phenomenology (i.e. an increase in blackbody temperature during the burst rise, and steady decrease in the decay), however, they required a variable NH. We found that the values of NH during the bursts were roughly double those found in the fits of the persistent emission prior to each burst. We interpret this change in absorption as evidence of burst–disc interaction, which we observe due to the high inclination of the system. We searched for burst oscillations during each burst and detected a signal in the first burst at the known spin frequency of the neutron star (517.92 Hz). This is the first time burst oscillations have been detected from Swift J1749.4-2807. We further find that each X-ray burst occurs on top of an elevated persistent count rate. We performed time-resolved spectroscopy on the combined data of the bursts with sufficient statistics (i.e. the clearest examples of this phenomenon) and found that the blackbody parameters evolve to hotter temperatures closer to the onset of the bursts. We interpret this as a consequence of an unusual marginally stable burning process similar to that seen through mHz QPOs.

Development of a Quasi-Quantitative Structure-Activity Relationship Model for Prediction of the Immobilization Response of Daphnia magna Exposed to Metal-Based Nanomaterials.

The conventional Hill equation model is suitable to fit dose–response data obtained from performing (eco)toxicity assays. Models based on quasi–quantitative structure–activity relationships (QSARs) to estimate the Hill coefficient (nH) were developed with the aim of predicting the response of the invertebrate species Daphnia magna to exposure to metal‐based nanomaterials. Descriptors representing the pristine properties of nanoparticles and media conditions were coded to a quasi–simplified molecular input line entry system and correlated to experimentally derived values of nH. Monte Carlo optimization was used to model the set of nH values, and the model was trained on the basis of reported dose–response relationships of 60 data sets (n = 367 individual response observations) of 11 metal‐based nanomaterials as obtained from 20 literature reports. The model simulates the training data well, with only 2.3% deviation between experimental and modeled response data. The technique was employed to predict the dose–response relationships of 15 additional data sets (n = 72 individual observations) not included in model development of seven metal‐based nanomaterials from 10 literature reports, with an average error of 3.5%. Combining the model output with either the median effective concentration value or any other known effect level as obtained from experimental data allows the prediction of full dose–response curves of D. magna immobilization. This model is an accurate screening tool that allows the determination of the shape and slope of dose–response curves, thereby greatly reducing experimental effort in case of novel advanced metal‐based nanomaterials or the prediction of responses in altered exposure media. This screening model is compliant with the 3Rs (replacement, reduction, and refinement) principle, which is embraced by the scientific and regulatory communities dealing with nano‐safety. Environ Toxicol Chem 2022;41:1439–1450. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The Influence of Household Size on Growth Pattern of Children Aged 5-12 Years from Kazaure Emirate, Jigawa State, Nigeria

Anthropometry is the measurement of different parts of the body and is an indicator of nutritional and health status. Socio-economic variables such as income, education, birth order, family size, and urbanization are associated with the physical development of children. The aim of the study was to determine the influence of house-hold (family) size on the growth pattern of children aged 5-12 years from Kazaure emirate, Jigawa State, Nigeria. A stadiometer was used to measure height to the nearest 0.1 cm and weight to the nearest 0.5 kg. A non-elastic measuring tape was used for the measurement of head, neck, chest, mid upper arm, hip, waist and calf circumferences to the nearest 0.1cm respectively. A Harpenden skin fold caliper was used for the measurement of biceps and triceps skin fold thicknesses to the nearest 0.1 mm respectively. It was a cross-sectional survey comprising of 863 pupils of Hausa ethnic group randomly selected from public primary schools in Kazaure emirate aged 5 - 12years. Males of household size between1-2, had higher values of HT, WT and body circumferences than females except hip circumference with statistical significant difference p<0.05 while females had higher values of biceps and triceps skinfold thicknesses with statistical difference p<0.05. Males of household size >2, had higher values of HT, WT, BMI and body circumferences than females with statistical difference (p<0.05) while females had higher values of skinfold thickness and HC with statistical difference (p=0.01). Males of household size 1-2, had higher values of cephalofacial dimensions than females with statistical difference (p<0.05) while females had higher values of nasal height and cephalic index than males with statistical difference p<0.05. Males of household size >2, had higher values of cephalofacial dimensions than females with statistical difference p<0.05 while females had higher values of NH and FI with statistical difference p<0.05. Males of household size 1-2 and >2, had higher values of upper and lower limbs dimensions than females with statistical difference p<0.05. In conclusion, it was observed that males grew better than females and, children from small family size had better growth than those from large family size.
 Keywords: Age, Household-size, Growth, Kazaure emirate, Nigeria

Nitrogen isotopes in the soil-to-tree continuum - Tree rings express the soil biogeochemistry of boreal forests exposed to moderate airborne emissions.

Anthropogenic N emissions represent a potential threat for forest ecosystems, and environmental indicators that provide insight into the changing forest N cycle are needed. Tree ring N isotopic ratios (δ15N) appear as a contentious choice for this role as the exact mechanisms behind tree-ring δ15N changes seldom benefit from a scrutiny of the soil-to-tree N continuum. This study integrates the results from the analysis of soil chemistry, soil microbiome genomics, and δ15N values of soil N compounds, roots, ectomycorrhizal (EcM) fungi and recent tree rings of thirteen white spruce trees sampled in five stands, from two regions exposed to moderate anthropogenic N emissions (3.9 to 8.1 kg/ha/y) with distinctive δ15N signals. Our results reveal that airborne anthropogenic N with distinct δ15N signals may directly modify the NO3- δ15N values in surface soils, but not the ones of NH4+, the preferred N form of the studied trees. Hence, the tree-ring δ15N values reflect specific soil N conditions and assimilation modes by trees. Along with a wide tree-ring δ15N range, we report differences in: soil nutrient content and N transformation rates; δ15N values of NH4+, total dissolved N (TDN) and EcM mantle enveloping the root tips; and bacterial and fungal community structures. We combine EcM mantle and root δ15N values with fungal identification to infer that hydrophobic EcM fungi transfer N from the dissolved organic N (DON) pool to roots under acidic conditions, and hydrophilic EcM fungi transfer various N forms to roots, which also assimilate N directly under less acidic conditions. Despite the complexities of soil biogeochemical properties and processes identified in the studied sites, in the end, the tree-ring δ15N averages inversely correlate with soil pH and anthropogenic N inputs, confirming white spruce tree-ring δ15N values as a suitable indicator for environmental research on forest N cycling.

Hot bubbles of planetary nebulae with hydrogen-deficient winds

Context.The first high-resolution X-ray spectroscopy of a planetary nebula, BD +30° 3639, opened the possibility to study plasma conditions and chemical compositions of X-ray emitting “hot” bubbles of planetary nebulae in much greater detail than before.Aims.We investigate (i) how diagnostic line ratios are influenced by the bubble’s thermal structure and chemical profile, (ii) whether the chemical composition inside the bubble of BD +30° 3639 is consistent with the hydrogen-poor composition of the stellar photosphere and wind, and (iii) whether hydrogen-rich nebular matter has already been added to the bubble of BD +30° 3639 by evaporation.Methods.We applied an analytical, one-dimensional (1D) model for wind-blown bubbles with temperature and density profiles based on self-similar solutions including thermal conduction. We also constructed heat-conduction bubbles with a chemical stratification. The X-ray emission was computed using the well-documented CHIANTI code. These bubble models are used to re-analyse the high-resolution X-ray spectrum from the hot bubble of BD +30° 3639.Results.We found that our 1D heat-conducting bubble models reproduce the observed line ratios much better than plasmas with single electron temperatures. In particular, all the temperature- and abundance-sensitive line ratios are consistent with BD +30° 3639 X-ray observations for (i) an intervening column density of neutral hydrogen,NH= 0.20-0.10+0.05× 1022cm−2, (ii) a characteristic bubble X-ray temperature ofTX= 1.8 ± 0.1 MK together with (iii) a very high neon mass fraction of about 0.05, virtually as high as that of oxygen. For lower values ofNH, we cannot exclude the possibility that the hot bubble of BD +30° 3639 contains a small amount of “evaporated” (or mixed) hydrogen-rich nebular matter. Given the possible range ofNH, the fraction of evaporated hydrogen-rich matter cannot exceed 3% of the bubble mass.Conclusions.The diffuse X-ray emission from BD +30° 3639 can be well explained by models of wind-blown bubbles with thermal conduction and a chemical composition equal to that of the hydrogen-poor and carbon-, oxygen-, and neon-rich stellar surface.

The influence of ammonia on groundwater quality during wastewater irrigation

Currently, agriculture in many countries including the Czech Republic is increasingly facing the problem of drought. The lack of precipitation results in a reduced harvest, which implies added irrigation and freshwater requirements. One of the ways to overcome the scarcity of fresh water is to search for alternative sources of irrigation water. The paper deals with a water source, which has not been preferred yet, but theoretically provides a wide application - treated municipal wastewater. Under a pilot plant, several selected soils were tested, placed in 2.0 m high filtration columns. Our observation was focused on ammonia nitrogen and its gradual decline during the flow through the soil profile. Samples from the filtration columns (inflow = irrigation; outflow = drainage water) were periodically taken, while the collected data were used for calibration of the numerical model. The model was calibrated in two successive separate steps, both were compiled in HYDRUS-2D. In the first step the model was calibrated according to the measured soil water content of materials. Subsequently, a second calibration was performed using the measured seepage concentrations of ammonia. Despite certain simplifications caused by the focus only on ammonia nitrogen, the model shows very favourable results. The hydraulic model’s goodness of fit (between observed vs. measured values of water content) is R<sup>2</sup> = 0.88 for sand, 0.76 for loam, 0.72 for sandy-loam with vegetation on surface and 0.74 for sandy-loam without vegetation. The calibrated hydraulic model for solute transport (between observed vs. measured values of NH<sub>4</sub><sup>+</sup>-N concentration) showed the value of R<sup>2</sup> = 0.89 for sand, 0.95 for loam, 0.95 for sandy-loam with vegetation on surface and 0.92 for sandy-loam without vegetation. The model provides significant information on the dependence of decrease of ammonia pollution by the depth. Inflow concentration of ammonia on surface 17 ± 1 mg/l is reduced to the value of 2.0 mg/l at a depth of 110 cm. It is crucial for real application to maintain the hydraulic criteria - the field capacity should not be exceeded in praxis. The value of field capacity was deliberately slightly exceeded because of understanding of the situation: how the pollution proceeds below if this rule is not followed. As a result, if wastewater is applied, the groundwater level should not be at a depth of less than 1.5 m.

Assessment of water quality status using univariate analysis at Klang and Juru River, Malaysia

Klang River and Juru River which today suffers from water quality problems resulting from anthropogenic and geomorphology factors . The purpose of this study was to assess the water quality status from 2009 until 2013. 10 monitoring stations covering along Klang River and Juru River were selected. Six water quality parameters analyzed based on in-situ and ex-situ analysis were carried out according to the univariate analysis to obtain WQI level. The result indicated the impact of various anthropogenic and geomorphology activities contributed higher values of BOD, COD, SS and NH 3 -NL but the TSS concentration contamination at Juru River still on stable condition. Downstream and middle stream more polluted than upstream area triggered by pollutants from waste products of development activities, which inclusion of a high amount of pollutants of Klang River and Juru River.

Characterisation of turbine behaviour for an engine overspeed prediction model

This paper focuses on the characterisation of turbine overspeed behaviour to be integrated into an engine overspeed model capable of predicting the terminal speed of the high pressure turbine (HPT) in the event of a high pressure shaft failure. The engine considered in this study features a single stage HPT with a shrouded contra-rotating rotor with respect to the single stage intermediate pressure turbine (IPT). The HPT performance is characterised in terms of torque and mass flow function for a range of expansion ratios at various non-dimensional rotational speeds (NH), up to 200% of the design value. Additionally, for each HPT expansion ratio and NH, the change in capacity of the downstream IPT, for different IPT non-dimensional rotational speeds (NI), also needs to be characterised due to the extremely positive incidence angle of the flow from the upstream rotor. An automated toolkit is developed to generate these characteristic maps for both the HPT and IPT.An unlocated high pressure shaft failure will result in rearward movement of the rotor sub-assembly. This causes changes in the rotor tip and rim seal regions, and in the rim seal leakage flow properties. Therefore, in the present work, a high fidelity characterisation of turbine behaviour with the inclusion of tip and rim seals is carried out at three different displacement locations, 0 mm, 10 mm and 15 mm, to improve terminal speed estimation. Furthermore, there is a possibility of damage to the tip seal fins of the HPT rotor due to unbalance in the spool that may result in contact between the rotor aerofoil tip and the casing. Consequently, another set of characteristics are generated with damaged tip fins at each displacement location.It is observed from the characteristics that the torque of the HPT rotor decreases with increasing NH. The HPT mass flow function initially decreases and then increases with an increase in NH. The IPT mass flow function initially remains similar and then decreases with increase in NH above values of 150%. The HPT rotor torque and IPT mass flow function decrease with rearward movement of the HPT rotor sub-assembly for all values of NH. With worn tip seal fins all parameters mentioned previously are lower than in the nominal undamaged case. The high fidelity characterisation of turbines that follows the sequence of events after a shaft failure, as described in this work, can provide accurate predictions of terminal speed and thus act as a tool for testing design modifications that can result in better management and control of the over-speed event.

Evolution of Negative Cooperativity in Glutathione Transferase Enabled Preservation of Enzyme Function

Negative cooperativity in enzyme reactions, in which the first event makes subsequent events less favorable, is sometimes well understood at the molecular level, but its physiological role has often been obscure. Negative cooperativity occurs in human glutathione transferase (GST) GSTP1-1 when it binds and neutralizes a toxic nitric oxide adduct, the dinitrosyl-diglutathionyl iron complex (DNDGIC). However, the generality of this behavior across the divergent GST family and its evolutionary significance were unclear. To investigate, we studied 16 different GSTs, revealing that negative cooperativity is present only in more recently evolved GSTs, indicating evolutionary drift in this direction. In some variants, Hill coefficients were close to 0.5, the highest degree of negative cooperativity commonly observed (although smaller values of nH are theoretically possible). As DNDGIC is also a strong inhibitor of GSTs, we suggest negative cooperativity might have evolved to maintain a residual conjugating activity of GST against toxins even in the presence of high DNDGIC concentrations. Interestingly, two human isoenzymes that play a special protective role, safeguarding DNA from DNDGIC, display a classical half-of-the-sites interaction. Analysis of GST structures identified elements that could play a role in negative cooperativity in GSTs. Beside the well known lock-and-key and clasp motifs, other alternative structural interactions between subunits may be proposed for a few GSTs. Taken together, our findings suggest the evolution of self-preservation of enzyme function as a novel facility emerging from negative cooperativity.

Some causes of differences in the NH<sub>3</sub> concentration measured with the semiconductor sensors by one manufacturer

The paper deals with continuous monitoring of NH<sub>3</sub> desorption from material used as bedding in animal breeding establishments, using five semiconductor sensors SP-53 (FIS Inc.). In lab experiments, two groups of sensors from two categories, to which the manufacturer divided the sensors based on the value of their resistance R<sub>S</sub>, were used. Also the influence of air humidity over the values of NH<sub>3</sub> concentrations measured by individual sensors was monitored. The study ascertained statistically relevant differences between NH<sub>3</sub> concentration values measured by both groups of sensors, in the range from 8.5% to 23.1%. The biggest differences were confirmed for relative air humidity around 85%. It was verified that setting a convenient value of the load resistance R<sub>L</sub> with regard to the R<sub>S</sub> of each sensor, along with the selection of limited range of measured temperatures and relative air humidity, leads to satisfactory correction of the sensor output data, regardless of the division of sensors in categories pursuant to the value of their resistance in manufacturing.

Evaluasi Biofermentasi Rumen Sapi Peranakan Ongole yang Diberi Pakan Berserat

<p><em>The experiment was conducted to evaluat</em><em>e the nutritional value of ground peanut straw, king grass and corn forage </em><em>and their ability </em><em>to provid</em><em>e nutrients for livestock in terms of rumen fermentation. Three rumen</em><em>-fistulated </em><em>PO </em><em>cattles were used </em><em>to investigate rumen fermentation parameter (pH,</em><em> NH<sub>3,</sub></em><em>VFA). The cattle</em><em>s were fed ground peanut straw (PS), king grass (KG) and corn forage (CF) ad libitum as single f</em><em>eed. The values of rumen fermentation parameters were analy</em><em>zed using</em><em> Analysis of Variance of Completely </em><em>Randomized Design.</em><em> The result showed that rumen pH,</em><em> and of cattle fed with PS,</em><em> KG and CF were 6.94, 6.68 and 6.71</em><em>, NH<sub>3</sub> </em><em>concentrations 13.71, 6.85 and 4.37mg/100ml</em><em>, and total VFA concentrations 48.99, 70.17 and 51.59 mmol/l, respectively. Values of pH and NH<sub>3</sub> concentration were significantly different (p<0.05) among </em><em>treatments, meanwhile VFA concentration were not significantly different. Ground peanut straw </em><em>resulted the highest rumen fermentation parameters.</em></p><p><em> </em></p><p><strong><em>Key </em></strong><strong><em>words</em></strong><em> : </em><em>Peranakan Onggole cattle, </em><em>fibrous </em><em>feed, </em><em>nutritive value, rumen </em><em>fermentation </em></p>

Effect of Split Fertilization on Subsurface Water Quality in Wild Blueberry Fields

Abstract. The majority of wild blueberry ( Ait.) fields are situated in acidic soils, having poor water holding capacities, weed patches, gentle to severe topography, and substantial proportion of bare spots, which emphasize the need for variable rate split (VRS) fertilization. Two commercial wild blueberry sites were selected in Nova Scotia, Canada to evaluate the impact of VRS fertilization on subsurface water contamination. The sites were divided into three sections [VRS section, uniform rate split (URS) section, and uniform rate (UR) section]. Prescription maps were generated with ArcGIS 10.1 software based on slope variation for VRS fertilization. Fertilization was performed based on the prescription maps using variable rate (VR) spreader. Fifty-four lysimeters were installed in VRS, URS, and UR treatment sections to collect subsurface water samples. Subsurface water samples were collected after every heavy rainfall event (>15 mm), and were analyzed for nitrate nitrogen (NO 3 - -N) and ammonium nitrogen (NH 4 + -N) concentrations. Leaf samples were collected from each fertilizer treatment and analyzed for macro and micro nutrients. Results suggested that the VRS treatment significantly decreased (p 3 - -N and NH 4 + -N concentrations in subsurface water samples when compared to URS and UR treatments. Overall for the Cooper site, mean NO 3 - -N leaching under the VRS treatment section were 45% and 47% lower as compared to the URS and UR treatment sections, respectively. However, mean values of NH 4 + -N concentration under the VRS treatment section of the North River site were 38% and 45% lower as compared to the URS and UR treatment sections, respectively. Results revealed that the VRS treatment did not have any negative effect on leaf nutrient concentrations. The VRS fertilization saved almost 40% in this study. Results demonstrated that the VRS fertilization in wild blueberry fields can increase fertilizer use efficiency and reduce water contamination via subsurface leaching.

Nitrogen Isotopic Fractionation Related to Nitrification Capacity in Agricultural Soils

A laboratory-based aerobic incubation was conducted to investigate nitrogen (N) isotopic fractionation related to nitrification in five agricultural soils after application of ammonium sulfate ((NH4)2SO4). The soil samples were collected from a subtropical barren land soil derived from granite (RGB), three subtropical upland soils derived from granite (RQU), Quaternary red earth (RGU), Quaternary Xiashu loess (YQU) and a temperate upland soil generated from alluvial deposit (FAU). The five soils varied in nitrification potential, being in the order of FAU > YQU > RGU > RQU > RGB. Significant N isotopic fractionation accompanied nitrification of NH+4. δ15N values of NH+4 increased with enhanced nitrification over time in the four upland soils with NH+4 addition, while those of NO+4 decreased consistently to the minimum and thereafter increased. δ15N values of NH+4 showed a significantly negative linear relationship with NH+4-N concentration, but a positive linear relationship with NO+4-N concentration. The apparent isotopic fractionation factor calculated based on the loss of NH+4 was 1.036 for RQU, 1.022 for RGU, 1.016 for YQU, and 1.020 for FAU, respectively. Zero- and first-order reaction kinetics seemed to have their limitations in describing the nitrification process affected by NH+4 input in the studied soils. In contrast, N kinetic isotope fractionation was closely related to the nitrifying activity, and might serve as an alternative tool for estimating the nitrification capacity of agricultural soils.

Ammonia concentration in farrowing pens with permanent limited range of motion for lactating sows

Livestock production significantly contributes to emissions of polluting gases emissions like ammonia (NH<sub>3</sub>) and greenhouse gases. Pig production is globally responsible for about 15% of ammonia emissions. The aims of this paper were the comparison of the ammonia concentrations in the farrowing pens with permanent limited range of motion between the zones of lactating sows and piglets and the impact of the day hour on ammonia concentration in this place. Photoacoustic infrared measuring devices INNOVA were used. The average values of NH<sub>3</sub> concentration ranged from 0.787738 ppm (0.547478 mg/m<sup>3</sup>) to 0.818091 ppm (0.568573 mg/m<sup>3</sup>). The minimum concentration of NH<sub>3</sub> was measured in the second lactating sows zone (0.262535 ppm, 0.182462 mg/m<sup>3</sup>) and the maximum concentration was measured in the piglets zone (1.61803 ppm, 1.124531 mg/m<sup>3</sup>). Values measured met the requirements of the Decree No. 230/1998 of the Ministry of Agriculture and Rural Development of the Slovak Republic which allows the maximum concentration of NH<sub>3</sub> in the pig building 20 ppm (13.9 mg/m<sup>3</sup>). There were no differences between the concentrations of the greenhouse gases (GHGes) in the zones of lactating sows and piglets.

Thermal Environment, Ammonia Concentrations, and Ammonia Emissions of Aviary Houses with White Laying Hens

Abstract. Maintaining comfortable thermal environments and good indoor air quality is essential to ensuring optimal production performance, welfare, and health of animals. Alternative laying-hen housing systems are being adopted by some egg producers in the U.S. However, information on indoor thermal and aerial environments of such alternative housing systems is meager. This article reports a one-year monitoring of thermal conditions (air temperature and relative humidity or RH) and ammonia (NH 3 ) concentrations and emissions of four aviary laying-hen houses (same dimensions, manure belt plus litter floor systems, 50,000-hen capacity each) at a commercial farm in the Midwest U.S. Carbon dioxide (CO 2 ) concentrations at the air inlet and near the exhaust fans were measured and used, along with literature values of the metabolic rates of the hens, to estimate building ventilation rate (VR). The results show that indoor temperature, RH, CO 2 concentration, NH 3 concentration, and VR of the four houses (mean ±standard deviation) were 23.4°C ±0.3°C, 64% ±3%, 1520 ±87 ppm, 5.2 ±0.4 ppm, and 4.5 ±0.6 m 3 h -1 hen -1 , respectively. The highest daily mean NH 3 concentration was 13 ppm (and 20 ppm within the day) in winter. The NH 3 emission rate was 0.14 ±0.01 g d -1 hen -1 . These values of NH 3 concentrations and emissions were lower than those reported for European aviary houses. The NH 3 emissions of the monitored aviary houses in this study are comparable to those of U.S. manure-belt cage houses, but are much lower than those of U.S. high-rise cage houses. The magnitude of NH 3 emissions observed in this study was consistent with that of similar aviary houses with brown hens in another extended field measurement in the same region.

Dust in active galactic nuclei

The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation and continuum luminosity are expected to be related to dust associated with the torus. Therefore, isolating the nuclear component is essential to study the MIR emission of AGN. We have compiled all the T-ReCS spectra (Gemini observatory) available in the N-band for 22 AGN: 5 Type-1 and 17 Type-2 AGN. The high angular resolution of the T-ReCs spectra allows us to probe physical regions of 57 pc (median). We have used a novel pipeline called RedCan capable of producing flux- and wavelength-calibrated spectra for the CanariCam (GTC) and T-ReCS (Gemini) instruments. We have measured the fine-structure [SIV] at 10.5 microns and the PAH at 11.3 microns line strengths together with the silicate absorption/emission features. We have also compiled Spitzer/IRS spectra to understand how spatial resolution influences the results. The 11.3 microns PAH feature is only clearly detected in the nuclear spectra of two AGN, while it is more common in the Spitzer data. For those two objects the AGN emission in NGC7130 accounts for more than 80% of the MIR continuum at 12 microns while in the case of NGC1808 the AGN is not dominating the MIR emission. This is confirmed by the correlation between the MIR and X-ray continuum luminosities. The [SIV] emission line at 10.5 microns, which is believed to originate in the narrow line region, is detected in most AGN. We have found an enhancement of the optical depth at 9.7 microns in the high-angular resolution data for higher values of NH. Clumpy torus models reproduce the observed values only if the host-galaxy properties are taken into account.

Exchange of nutrients and oxygen across the sediment–water interface below a Sparus aurata marine fish farm in the north-western Mediterranean Sea

This study analyzes the effects of aquaculture activities in open seawater in the north-western coastal waters of the Mediterranean Sea. It is the first of its kind to be based on benthic flux data gathered in situ below fish farms for this particular area. Samples were collected on four sampling campaigns over a 1-year cycle under a Sparus aurata fish farm facility where benthic fluxes were measured in situ using light and dark benthic chambers. Bottom water and sediment samples were also collected. Data were compared to those for a nearby control station. Significant differences were found (ANOVA, p < 0.05) between concentrations of organic matter (OM), total phosphorus and redox potentials in sediments located under the cages and those of the control station. The consumption of dissolved oxygen (DO) by sediment and positive ammonium (NH 4 + ) fluxes was stimulated by OM content, with correlations of r = −0.60 (p < 0.01) and r = 0.70 (p < 0.01), respectively. The OM content of sediments was found to be consistently higher under the cages than at the control station, with the highest value (1.8 ± 0.7 %) under the cages observed during the early summer; values of DO and NH 4 + fluxes were −64 ± 17 and 12.7 ± 1.0 mmol m−2 day−1, respectively. PO 4 3– fluxes were consistently higher in the fish farm sediments (between 0.58 and 0.98 mmol m−2 day−1) than those observed at the control station. Nitrate (NO 3 − ) fluxes were found to be consistently negative due to denitrification occurring in the sediments and were related to the concentration of NO 3 − in bottom waters (r = 0.92, p < 0.01). Si fluxes were shown to be associated with water temperature (r = 0.59, p < 0.05). The results imply that sediments located below cages accumulate organic matter originating from aquaculture activities, especially during summer months when this activity increases. Sediments undergo biogeochemical changes that mainly affect fluxes of DO, NH 4 + and soluble reactive phosphorus, although these do not seem to have a significant impact on the quality of the water column due to the hydrodynamic characteristics of the area.

Riluzole blocks human muscle acetylcholine receptors

Riluzole, the only drug available against amyotrophic lateral sclerosis (ALS), has recently been shown to block muscle ACh receptors (AChRs), raising concerns about possible negative side-effects on neuromuscular transmission in treated patients. In this work we studied riluzole's impact on the function of muscle AChRs in vitro and on neuromuscular transmission in ALS patients, using electrophysiological techniques. Human recombinant AChRs composed of α(1)β(1)δ subunits plus the γ or ε subunit (γ- or ε-AChR) were expressed in HEK cells or Xenopus oocytes. In both preparations, riluzole at 0.5 μm, a clinically relevant concentration, reversibly reduced the amplitude and accelerated the decay of ACh-evoked current if applied before coapplication with ACh. The action on γ-AChRs was more potent and faster than on ε-AChRs. In HEK outside-out patches, riluzole-induced block of macroscopic ACh-evoked current gradually developed during the initial milliseconds of ACh presence. Single channel recordings in HEK cells and in human myotubes from ALS patients showed that riluzole prolongs channel closed time, but has no effect on channel conductance and open duration. Finally, compound muscle action potentials (CMAPs) evoked by nerve stimulation in ALS patients remained unaltered after a 1 week suspension of riluzole treatment. These data indicate that riluzole, while apparently safe with regard to synaptic transmission, may affect the function of AChRs expressed in denervated muscle fibres of ALS patients, with biological consequences that remain to be investigated.

First-principles calculation of thermodynamic stability of acids and bases under pH environment: A microscopic pH theory

Despite being one of the most important thermodynamic variables, pH has yet to be incorporated into first-principles thermodynamics to calculate stability of acidic and basic solutes in aqueous solutions. By treating the solutes as defects in homogeneous liquids, we formulate a first-principles approach to calculate their formation energies under proton chemical potential, or pH, based on explicit molecular dynamics. The method draws analogy to first-principle calculations of defect formation energies under electron chemical potential, or Fermi energy, in semiconductors. From this, we propose a simple pictorial representation of the general theory of acid-base chemistry. By performing first-principles molecular dynamics of liquid water models with solutes, we apply the formulation to calculate formation energies of various neutral and charged solutes such as H(+), OH(-), NH(3), NH(4)(+), HCOOH, and HCOO(-) in water. The deduced auto-dissociation constant of water and the difference in the pKa values of NH(3) and HCOOH show good agreement with known experimental values. Our first-principles approach can be further extended and applied to other bio- and electro-chemical molecules such as amino acids and redox reaction couples that could exist in aqueous environments to understand their thermodynamic stability.