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Life-as-we-know-it harnesses carbon for the scaffolding in biomolecules and liquid water as the solvent. This chapter delineates the beneficial properties of carbon and water, and then investigates whether viable alternatives to this duo exist (i.e., ‘exotic’ life). With regard to the latter, the likes of ammonia, sulfuric acid, and liquid hydrocarbons are expected to have some physical and/or chemical advantages relative to water, while also exhibiting certain downsides. In contrast, it is suggested that few options appear feasible aside from carbon, with silicon representing a partial exception. The chapter subsequently delves into the habitability of the clouds of Venus and the lakes of Titan, because the alternative solvents sulfuric acid and liquid hydrocarbons (methane and ethane) are, respectively, documented therein. Both these environments might be conducive to hosting exotic life, but it is cautioned that they are likely subjected to severe challenges.
In order to study the structure and temperature distribution within high-mass star-forming clumps, we employed the Australia Telescope Compact Array to image the $\mathrm{NH}_3$ (J,K) = (1,1) through (6,6) and the (2,1) inversion transitions, the $\mathrm{H}_2\mathrm{O}$$6_{16}$-$5_{23}$ maser line at 22.23508 GHz, several $\mathrm{CH}_3\mathrm{OH}$ lines and hydrogen and helium recombination lines. In addition, 22- and 24-GHz radio continuum emission was also imaged.
The $\mathrm{NH}_3$ lines probe the optical depth and gas temperature of compact structures within the clumps. The $\mathrm{H}_2\mathrm{O}$ maser pinpoints the location of shocked gas associated with star formation. The recombination lines and the continuum emission trace the ionised gas associated with hot OB stars. The paper describes the data and presents sample images and spectra towards select clumps. The technique for estimating gas temperature from $\mathrm{NH}_3$ line ratios is described. The data show widespread hyperfine intensity anomalies in the $\mathrm{NH}_3$ (1,1) images, an indicator of non-LTE $\mathrm{NH}_3$ excitation. We also identify several new $\mathrm{NH}_3$ (3,3) masers associated with shocked gas. Towards AGAL328.809+00.632, the $\mathrm{H}_2\mathrm{O}$$6_{16}$-$5_{23}$ line, normally seen as a maser, is instead seen as a thermally excited absorption feature against a strong background continuum. The data products are described in detail.
In this study, the effects of two different ammonium-exchange methods to improve the ammonia (NH3) gas adsorption of raw clinoptilolite (CLN) from Gördes (Türkiye) was investigated. The first method involved direct modification of CLN by 0.5 or 1.0 M NH4NO3 solutions at 80°C for 4 and 8 h followed by calcination. In the second method, CLN was converted to the Na+ form prior to modification with ammonium nitrate and calcination under the same conditions. Both methods yielded H+ forms of CLN through the removal of exchangeable cations without damaging the crystal structure. Ammonia adsorption isotherms were determined at 298 K for a total of eight different H+ forms synthetized using both methods. The Na-1.0-8h CLN sample with the highest NH3 adsorption capacity obtained using the second method was selected as the parent CLN. In addition, to determine the effects of doping different cations into the structure on the NH3 adsorption properties of the selected parent CLN sample, cation-exchange processes were carried out using 0.5 and 1.0 M NaNO3, KNO3, Ca(NO3)2 and Mg(NO3)2 solutions at 80°C for 4 h. The raw and modified CLNs were characterized using X-ray diffraction, X-ray fluorescence, scanning electron microscopy and N2 adsorption analyses. Cation-exchanged samples with a wide range of NH3 adsorption capacities (3.61–4.93 mmol g–1) were compared with other zeolites from the literature.
Hydrogen as a carbon-free fuel is amenable to utilization in all heat engines, including gas turbines and reciprocating internal combustion engines, which are the most efficient technologies for electric power generation from fossil fuels. Alas, H2 is not an energy resource. It is an energy carrier. Prior to its use as a fuel, it must be produced, stored and/or transported. There are significant problems associated with all three phases of the hydrogen fuel chain. Those aspects will be discussed qualitatively and quantitatively in the remainder of the present chapter.
Reducing dietary crude protein (CP) concentration while maintaining adequate amino acid (AA) supply by free AA inclusion can contribute to attenuate the negative environmental effects of animal farming. This study investigated upper limits of dietary free AA inclusions without undesirable effects including the dependence on asparagine (Asn) and glutamine (Gln) supply. Ten broilers were allocated to sixty-three metabolism units each and offered nine experimental diets from day (d) 7–21 (n 7). One diet (167 g CP/kg) contained 80 g soya protein isolate (SPI)/kg. In the other diets, 25, 50, 75 and 100 % of the digestible AA from SPI were substituted with free AA. Digestible Asn+aspartic acid (Asp) and Gln+glutamic acid (Glu) were substituted with Asp/Glu or 50/50 mixes of Asp/Asn and Glu/Gln, respectively. Total excreta were collected from d 11–14 and from d 18–21. Growth and nitrogen accretion were unaffected by 25 and 50 % substitution without and with free Asn/Gln, respectively, but decreased at higher substitution (P ≤ 0·024). Circulating concentrations of Asp, Glu and Gln were unaffected by treatment, while Asn decreased at substitution higher than 50 % when Asn/Gln were not provided (P ≤ 0·005). Blood gas analysis on d 21 indicated a compensated metabolic acidosis at substitution higher than 50 and 75 % without and with free Asn/Gln, respectively (P ≤ 0·017). Results suggest that adding Asn/Gln increased an upper limit for proportion of dietary free AA from 10 to 19 % of dietary CP and enabled higher free AA inclusion without affecting the acid–base balance.
The three UCHII regions associated with the G34.26+0.15 high-mass star formation complex in Aquila are described, giving evidence for envelope infall, protostellar outflows, expanding ionized gas, and associated molecular hot core chemistry. The prototypical ‘cometary’ UCHII region ‘C’ in G34.26 is one focus, where the interface between ionized hydrogen (HII) and hot molecular core (HMC) gas is well observed and a rich hot core chemistry both detected and modelled in detail. Uncertainties in CH3CN formation, and the displacement of its peak emission from dust and NH3 peaks, are raised in relation to possible photodissociation in the hot core close to the UCHII-C feature.
Gas turbines are able to utilize a wide variety of fuels, including fuels with low- or zero-carbon content. This includes hydrogen (H2), ammonia (NH3), synthetic and renewable natural gas, as well as a range of biofuels. These are sometimes referred to as zero-carbon, net-zero-carbon, or near-zero-carbon fuels. A subset of these fuels have been used to produce power from gas turbines for decades. This chapter will review experience and practical challenges in the use of these fuels in gas turbines for power generation applications, describing case studies for utilizing these fuels in the field.
A major motivation for the development and ultimate replacement of petroleum-based fuels with alternatives is the desire to reduce the carbon emissions (i.e., CO2) created when burning hydrocarbon fuels in prime mover devices. In addition to CO2, combustion of hydrocarbon fuels in air will inevitably create a number of other emissions (e.g., NOx, soot, etc.), which can have detrimental effects on human health or the local (or global) environment. Furthermore, the desire for a more economic and stable fuel supply has also provided impetus for the identification of alternative feedstocks for fuels. With these motivations to find alternative fuels for power generation, it is important to understand how different fuels can impact pollutant formation. This chapter focuses on the fundamentals of pollutant formation in combustion, as well as the impact of various alternative fuels on the combustion generated emissions. This includes carbon monoxide, nitrogen oxides (NOx), and soot. These topics are addressed for a variety of candidate fuels, including hydrogen and ammonia.
Gas turbines are able to utilize a wide variety of fuels, including fuels with low- or zero-carbon content. This includes hydrogen (H2), ammonia (NH3), synthetic and renewable natural gas, as well as a range of biofuels. These are sometimes referred to as zero-carbon, net-zero-carbon, or near-zero-carbon fuels. A subset of these fuels have been used to produce power from gas turbines for decades. This chapter will review experience and practical challenges in the use of these fuels in gas turbines for power generation applications, describing case studies for utilizing these fuels in the field.
A major motivation for the development and ultimate replacement of petroleum-based fuels with alternatives is the desire to reduce the carbon emissions (i.e., CO2) created when burning hydrocarbon fuels in prime mover devices. In addition to CO2, combustion of hydrocarbon fuels in air will inevitably create a number of other emissions (e.g., NOx, soot, etc.), which can have detrimental effects on human health or the local (or global) environment. Furthermore, the desire for a more economic and stable fuel supply has also provided impetus for the identification of alternative feedstocks for fuels. With these motivations to find alternative fuels for power generation, it is important to understand how different fuels can impact pollutant formation. This chapter focuses on the fundamentals of pollutant formation in combustion, as well as the impact of various alternative fuels on the combustion generated emissions. This includes carbon monoxide, nitrogen oxides (NOx), and soot. These topics are addressed for a variety of candidate fuels, including hydrogen and ammonia.
The ammonia removal ability of heterotrophic bacteria Alcaligenes faecalis strain No.4 isolated from sewage sludge was examined in a batch operation to mitigate ammonia from piggery wastewater, consequently preventing pollution by the inflow of wastewater from piggeries adjacent to rivers. If this process works functionally, it can be effective in controlling nitrous oxide (N2O) and nitrate (NO3−) emissions derived from animal agriculture, the heterotrophic nitrifying and the aerobic denitrifying effect of A. faecalis strain No.4 on high-strength ammonium (NH4+-N) were evaluated in wastewater collected from a piggery. The removal rate by A. faecalis strain No.4 on high-strength ammonium (NH4+-N) was 0.97 kg N/m3/day which was more than 100 fold greater than that achieved using conventional aerobic nitrification and anaerobic denitrification processes. An aerobic one-step denitrification system using A. faecalis strain No.4 can be proposed to remove ammonia and phytopathogens from piggery wastewater with high efficiency and prevent water pollution in adjacent rivers.
The presence of ammonium on Ceres was first speculated based on telescopic data in the 1990s. Subsequent data from Dawn unambiguously confirmed the presence on Ceres’s surface. Ammonium has been identified within near-ubiquitous dark materials, and in salts in few localized bright faculae in the interiors of craters as we describe further in this chapter.
The presence of ammonium on Ceres is significant because it implies the availability of ammonia during its evolution. More broadly, understanding the processes that led to the presence of ammonium on Ceres provides important information on the aqueous environments in the early Solar System and the origins and dynamical histories of the large outer main belt asteroids. We briefly review the significance of ammonia and then describe what was known or speculated about ammoniated species on Ceres before Dawn’s arrival. We then review findings of the Dawn mission, in particular the detection and mapping of ammoniated phases by the Visible and Infrared spectrometer (VIR): which species host ammonia/ammonium, their abundance, and spatial distribution. We then discuss the potential origins and implications of ammonia, drawing on laboratory studies and modeling efforts. Finally, we summarize the key findings and the outstanding questions that remain for future investigation.
1. Encephalopathy describes potentially reversible neuropsychiatric abnormalities that are common in those with liver failure.
2. A wide range of motor and cognitive defects are described in hepatic encephalopathy, with clinical grading by the West Haven classification.
3. Investigations are useful to determine the aetiology of encephalopathy and to exclude differentials.
4. Whilst there is a clear role for ammonia in the pathogenesis, raised ammonia levels are not necessary or sufficient for a diagnosis of hepatic encephalopathy.
5. Management is aimed at correcting the underlying precipitant, lowering systemic ammonia absorption, and managing symptoms and complications.
In this study, the adsorption of NH3 gas on a bentonite from Ünye (Turkey) in its natural state and after acid treatments, was investigated experimentally at 298 K and up to 100 kPa. Bentonite was treated with HCl solutions of various concentrations (0.5–2.5 M) at 75°C for 4 h. X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 adsorption and thermogravimetric/differential thermal analysis (TG/DTA) were used to characterize the bentonite before and after acid treatment. The quantitative XRD analysis demonstrated that the bentonite sample was composed predominantly of smectite (75%), with abundant feldspar (20%) and minor opal-CT, analcime and quartz (5%). Increasing gas adsorption values of acid-treated bentonites were analysed depending on the structural changes of the clay. The NH3-adsorption capacities of the bentonite samples (3.801–5.068 mmol g–1) were also compared with previously studied clay-based materials (0.828–4.000 mmol g–1) in terms of their textural and structural differences.
We review key findings of one the most cited papers in the 75-year history of BJN. We then identify important consequent developments, as well as opportunities to use analytical and molecular biology advances to maximise conversion of non-protein nitrogen into microbial protein.
The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P < 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P < 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.
The aim of the present work was to compare the capacity to modulate the intestinal microbiota and the production of metabolites after 14 d administration of a commercial dietary supplement and a manufactured ice cream, both containing the same quantity of inulin and the same viable counts of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis BB-12, using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) model. Samples of the colonic contents were evaluated microbiologically by real-time quantitative PCR (qRT-PCR) and next-generation sequencing and chemically by the production of SCFA (acetate, propionate and butyrate) and ammonium ions ($\text{NH}_4^ + $). Statistical analyses were carried out for all the variables using the two-way ANOVA followed by the Tukey multiple comparisons test (P < 0·05) for metabolite production, qRT-PCR and the bioinformatics analysis for microbiota diversity. Dietary supplement and ice cream were able to deliver the probiotic L. acidophilus and B. animalis to the simulated colon and modulate the microbiota, increasing beneficial micro-organisms such as Bifidobacterium spp., Bacteroides spp. and Faecalibacterium spp. for dietary supplement administration, and Lactobacillus spp. for ice cream supplementation. However, the ice cream matrix was probably more favourable for the maintenance of the metabolic activity of the probiotics in the SHIME® model, due to the larger amounts of acetate, propionate, butyrate and ammonium ions obtained after 14 d of supplementation. In conclusion, both ways of probiotic supplementation could be efficient, each with its own particularities.
We discuss here the choice of solid compounds and materials which best suit various types of applications, focusing mainly on the polarized targets. These materials include hydrogen-rich glassy hydrocarbons and simple cubic crystalline ammonia and lithium hydrides. The glassy hydrocarbons can doped by dissolved stable free radicals, while crystalline materials are doped by radiolytic paramagnetic radicals. The leading application of DNP up till now has been the scattering experiments in high-energy and nuclear physics. Other applications include measurements of slow neutron cross-sections, molecular physics using slow neutrons, nuclear magnetism and other solid-state physics experiments, and spin filters. The use of polarized solids in fusion and in magnetic resonance imaging has also been discussed. The material choice evidently depends strongly not only on the application but also on the goal of the experiment or process which is considered. More recently DNP has been used for the signal enhancement in NMR studies of complex chemical and biochemical molecules. In this context DNP and other enhancement techniques are called by the term “hyperpolarization”.
Temperate pasture species constitute a source of protein for dairy cattle. On the other hand, from an environmental perspective, their high N content can increase N excretion and nitrogenous gas emissions by livestock. This work explores the effect of energy supplementation on N use efficiency (NUE) and nitrogenous gas emissions from the excreta of dairy cows grazing a pasture of oat and ryegrass. The study was divided into two experiments: an evaluation of NUE in grazing dairy cows, and an evaluation of N-NH3 and N-N2O volatilizations from dairy cow excreta. In the first experiment, 12 lactating Holstein × Jersey F1 cows were allocated to a double 3 × 3 Latin square (three experimental periods of 17 days each) and subjected to three treatments: cows without supplementation (WS), cows supplemented at 4.2 kg DM of corn silage (CS) per day, and cows supplemented at 3.6 kg DM of ground corn (GC) per day. In the second experiment, samples of excreta were collected from the cows distributed among the treatments. Aliquots of dung and urine of each treatment plus one blank (control – no excreta) were allotted to a randomized block design to evaluate N-NH3 and N-N2O volatilization. Measurements were performed until day 25 for N-NH3 and until day 94 for N-N2O. Dietary N content in the supplemented cows was reduced by 20% (P < 0.001) compared with WS cows, regardless of the supplement. Corn silage cows had lower N intake (P < 0.001) than WS and GC cows (366 v. 426 g/day, respectively). Ground corn supplementation allowed cows to partition more N towards milk protein compared with the average milk protein of WS cows or those supplemented with corn silage (117 v. 108 g/day, respectively; P < 0.01). Thus, even though they were in different forms, both supplements were able to increase (P < 0.01) NUE from 27% in WS cows to 32% in supplemented cows. Supplementation was also effective in reducing N excretion (761 v. 694 g/kg of Nintake; P < 0.001), N-NH3 emission (478 v. 374 g/kg of Nmilk; P < 0.01) and N-N2O emission (11 v. 8 g/kg of Nmilk; P < 0.001). Corn silage and ground corn can be strategically used as feed supplements to improve NUE, and they have the potential to mitigate N-NH3 and N-N2O emissions from the excreta of dairy cows grazing high-protein pastures.