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Polypyrrole (PPy)–Zn₂SnO₄ nanocomposites with different weight percentages (0–20%) of Zn₂SnO₄ were successfully prepared by chemical oxidative polymerization. The prepared nanocomposites were deposited on epoxy glass substrate using a spin coating technique and have been characterized using various techniques such as X-ray diffractometer, field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR) spectrometer. The physicochemical characterization confirmed well-formed dodecylbenzene (DBSA)-doped PPy–Zn₂SnO₄ nanocomposites with granular morphology and high porosity. Among various nanocompositions, DBSA-doped PPy–Zn₂SnO₄ (10 wt.%) nanocomposite was found to be highly sensitive towards NH₃ vapor at room temperature i.e. with a chemiresistive response of 5.44% at 27 ppm with a reasonably fast recovery time of 76 s. Additionally, it shows a linear response and appropriate recovery time at all concentrations of NH₃ vapor. The DBSA-doped PPy–Zn₂SnO₄ nanocomposite response is four times better than pure PPy toward NH₃ vapor at room temperature. Therefore, it is expected that such material with excellent gas sensing properties at room temperature can be used for high-performance NH₃ sensors.

Excellent properties of gallium nitride (GaN) make it an ideal material for realizing gas sensors, especially for ammonia (NH${}_3)$ detection. Although many researchers have pursued to describe the characteristics of GaN-based NH₃ gas sensors by different approaches, few models have been reported. In this paper, with the consideration of the exponential distribution of interfacial states, a model for ammonia concentration detection of GaN gas sensors has been presented. The Poisson equation is applied to model the effect of defect states on the potential. By taking advantage of the current-voltage characteristics, the value of Schottky barrier height can be obtained. The concentration of the adsorbed NH₃ gas is derived by exploiting the surface potential. It indicates that densities of acceptor interfacial trap states are in the order of 10${}^{11}\sim 10^{12}$cm${}^{-2}$eV${}^{-1}$. The current increases with the NH₃ concentration at the same applied voltage. In addition, detailed investigations of physical mechanisms and the analysis of the sensitivity have been depicted. It shows that the sensitivity followed an approximately exponential dependence on NH₃ density. Results compared well with experimental data that verify the proposed model and simulation method.

Recent progress in the study of motions and reactions of single adsorbed molecules on metal surfaces induced by inelastic tunneling electrons with a scanning tunneling microscope (STM) is given an overview, with the focus on our current theoretical understanding of the elementary processes behind these phenomena. The selected topics include rotation and dissociation of O₂ on Pt(111), rotation of a C₂H(D)₂ on Cu(100), lateral hopping of CO on Pd(110), lateral translation and desorption of NH₃ on Cu(100), and controlled manipulation of chemical transformation as well as bimolecular reaction of coadsorbed species on metal surfaces. Brief descriptions are presented of how an adsorbate to overcome the potential barrier for motion and reaction by incoherent stepwise and coherent single multistep climbing of the vibrational ladders in the potential well along the reaction coordinate, and indirect excitation of the reaction coordinate mode via anharmonic coupling to the vibrational mode excited by tunneling current. Elementary processes of the mode-selective control of different motions are also discussed in conjunction with a recent experimental result of lateral hopping and desorption of a single NH₃ molecule on Cu(100). Although still at a premature stage, these novel phenomena open a new world of "nano-surface-science," in which the manipulation and reaction of single adsorbates, and synthesis of a new molecular system are realized by a selective excitation of the relevant vibrational mode by tunneling electrons with an STM.

A novel and uncomplicated method for preparing nanocrystalline zinc oxide by precipitation in a basic aqueous solution with the addition of an oxidation agent and in the presence of flowing gas is presented. Firstly, the value of pH of the starting solution containing the zinc salts is adjusted to a value of 5–5.5. Then, zinc oxide is precipitated by adding NH₄OH and bubbling flowing air. Finally, the precipitated materials are washed with a basic solution (0.01 M NaOH). The X-ray diffraction patterns show nanocrystalline single-phase ZnO with a grain size of 12–14 nm (Scherrer method). No further thermal treatment of the prepared material is required. The surface of the prepared material can be successfully modified. This new route is reproducible and can be used on industrial level.

Recently, Xiong et al. reported an activation of ammonia by p-dimethylaminopyridine (DMAP) coordinated silanone (DMAP→Si(L)=O, DS) affording a unique pair of sila-hemiaminal (SH) and silanoic amide (SA) tautomers (Xiong Y, Yao S, Müller R, Kaupp M, Driess M, J Am Chem Soc132:6912, 2010). In this paper, the mechanisms of the activation of ammonia affording SH and SA, the successive generation of hydrogen bonded complex pair SH–SA and the tautomerization between SH and SA have been intensively investigated computationally for the first time at MP2/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level in toluene. The concerted Paths C and D with ammonia assistance are determined by our calculations to be the dominant pathways corresponding to forming SH and SA from DS, respectively. The free energy barrier of Path C affording SH from DS is 14.45 kcal/mol, and that of Path D affording SA is 21.46 kcal/mol. So it is determined theoretically that Path C is dynamically dominant over Path D. And the pair SH–SA is formed then spontaneously by intermolecular hydrogen bond (O–H ⋯ O′) without any barrier. While the tautomerization between SH and SA is nonsignficant resulting from the corresponding relative high barriers (23.79 kcal/mol for process from SH to SA and 26.52 kcal/mol for process from SA to SH). Our results are in good agreement with and good interpretation of the experimental results by Xiong et al.

This study describes the application of porphyrin-embedded porous organosilicate materials to the adsorption of ammonia gas. Organosilicate scaffolds were synthesized through a surfactant-templating process combined with a phase separation technique. The structure offers a macro-textured scaffold to facilitate flow through the sorbent material and provide enhanced access to the available surface area provided by a combination of micro- and mesopores distributed over a range of sizes. The materials were grafted post-synthesis to provide sites for covalent immobilization of porphyrins. These porphyrins were utilized for incorporation of metal sites into the organosilicate materials. The removal of ammonia was evaluated for a number of materials incorporating copper metalloporphyrins of varied structure at varied loading levels. Results have been compared to removal of ammonia by a carbon material. Copper deuteroporphyrin IX bis-ethylene glycol provided the strongest interactions with ammonia. High loading levels of this porphyrin within the sorbent structure showed increasing evidence of stacking and did not improve the performance of the material.

In the present work, the optical response of CoPcF₁₆ films upon exposure to ammonia vapor in the concentration range 50 to 1000 ppm was measured by total internal reflection ellipsometry. It was demonstrated that the sorption of NH₃ molecules causes substantial shift of the Δ(λ) spectrum which is determined by the increase in film thickness and change of its optical parameters. It was found that the CoPcF₁₆ films deposited at substrate temperature of 220 °C are characterized by larger grains and more developed surface demonstrating higher optical response than films deposited at substrate temperature of 60 °C. In order to gain an insight into the sorption mechanism at molecular level, we have studied the interaction of ammonia vapor with hexadecafluorinated cobalt phthalocyanine using infrared spectroscopy. It was shown that the detection of ammonia was found to be governed primarily by coordination to the metal center.

In the present work, we determined the electrical properties of octachlorinated metallophthalocyanines with Co(II) and Cu(II) ions as metal centers. We engaged them in heterojunctions, with lutetium bisphthalocyanine as a partner. Surprisingly, cobalt and copper complexes show opposite behaviors, the first being an $n$-type material whereas the latter is a $p$-type material, as deduced from the response of the heterojunctions towards ammonia; showing the unusual key role played by the metal center. While the LuPc${}_{\mathrm{\text{2}}}$/Cu(Cl${}_{\mathrm{\text{8}}}$Pc) complex exhibits a negative response to ammonia, the LuPc${}_{\mathrm{\text{2}}}$/Co(Cl${}_{\mathrm{\text{8}}}$Pc) complex exhibits a positive response to ammonia, with a sensitivity of 1.47% ppm${}^{\mathrm{\text{-1}}}$ at concentrations lower than 10 ppm and a limit of detection of 250 ppb. All the devices operate at room temperature and in real atmosphere.

Isoindole-diimine, which can be obtained by bubbling ammonia gas into a solution of phthalonitrile derivatives in the presence of Na${}^{+}$ ion, is a final and best precursor for phthalocyanine synthesis. In this study, isoindole-diimine and various derivatives have been prepared without bubbling ammonia gas using in situ generated ammonia that was produced from formamide and a strong alkali such as NaOH and NaNH₂. A longer reaction time, higher temperature, and larger amount of formamide were required for phthalonitrile derivatives with electron-donating groups, but this method is recommendable in that an NH₃ gas cylinder and concomitant gas regulator, which are not inexpensive, are not required. Attempts were made to interpret the IR and absorption spectra of the resultant diimines. The signals due to imino proton or N-H of diimino compounds were experimentally found to appear at around 8.2$\sim$9.5 ppm in ¹H-NMR and ca. 3500–3000 cm${}^{-1}$ in IR spectra.

Chemical injury to the eye is still an important cause of blindness and serious complications. Gaseous ammonia combines with tissue water to form ammonium hydroxide (NH₄OH). This exothermic reaction results in both heat and chemical burns. Although, over the years, the different biological effects of anhydrous ammonia are well known, its ocular effects are less clearly documented. This study reports the corneal structural alterations that may be induced as a result of ammonia exposure (gas or liquid) that was studied by Fourier transform infrared spectroscopy. The resulted IR spectra were analyzed using the band enhancement procedure. The obtained data clearly indicate that there are different structural and conformational changes (includes lipids and proteins) as the method of exposure to the ammonia differ, and due to the increased ammonia occupational exposure, there is an insistent need for the development of ophthalmic medications.

Resorption refrigeration system, a novel type of chemisorption technique, employs two or more inorganic salts as sorbent reactants, which co-operate as working pair. The working conditions and some evaluation indicators of the resorption system with different working pairs in previous studies are collected and summarized in this work. The performance of the reactant salts is compared, and further effort direction of the selection of working pairs is also analyzed.

The existing artificial and chemical refrigerants have been phased out due to environmental concerns, and they have been replaced with environmentally friendly refrigerants. Among them, carbon dioxide, ammonia, and hydrocarbons are paid attention as next generation refrigerants, and their application has been widely expanded. Therefore, in this paper, the latest studies of flow boiling and condensation heat transfer characteristics of carbon dioxide, ammonia, and hydrocarbon are reviewed. The heat transfer characteristics of ammonia and hydrocarbon show the relatively similar trends with the conventional refrigerants compared to those of carbon dioxide. The general trends and recommendable models of flow boiling and condensation heat transfer with carbon dioxide, ammonia, and hydrocarbons are summarized.

Presently, to enhance the thermal efficiency of a gas turbine power plant, turbine inlet air cooling (TIAC) is the widely used technique. The conventional refrigeration methods like vapor compression refrigeration and evaporative cooling need electric power, hence absorption and adsorption refrigeration systems are attractive options as they can be powered using the waste heat energy of the exhaust gases. Adsorption system has advantages over absorption system like scalability, requirement of lower heat source temperature, absence of corrosion and crystallization. This paper focuses on the thermodynamic analysis of waste heat powered adsorption chiller used for the cooling of intake air to enhance the net power output of the gas turbine power plant. This paper also presents a comparative analysis of the vapor-adsorption cycle-based TIAC system for four different refrigerants viz. HFC-134a, carbon dioxide, ethanol and ammonia with the motive of finding a substitute refrigerant for HFC-134a which has a high global warming potential (GWP). The adsorption chiller is mathematically modeled in MATLAB with activated carbon as the adsorbent and each one of carbon dioxide, ethanol and ammonia as the adsorbate. The variation of the coefficient of performance (COP) and specific cooling effect (SCE) with varying adsorption temperatures is presented for each pair. The net power output and primary energy rate (PER) improvement of the gas turbine power plant at different ambient temperatures are also discussed. It is observed that ammonia can improve the power plant performance significantly better compared to the other three refrigerants at ambient temperatures less than 40${}^{\circ }$C.

Ammonia is a natural compound, used more and more in refrigeration installations of absorption and vapor compression, component sizing and more particularly evaporators pass by the mastery and prediction of heat transfer. Our study aims to retrieve experimental data from the literature and verify them with known author correlations, and the differences were observed with margins of error; a new correlation has been developed giving convincing results.

Some people think that carbon and sustainable development are not compatible. This textbook shows that carbon dioxide (CO₂) from the air and bio-carbon from biomass are our best allies in the energy transition, towards greater sustainability. We pose the problem of the decarbonation (or decarbonization) of our economy by looking at ways to reduce our dependence on fossil carbon (coal, petroleum, natural gas, bitumen, carbonaceous shales, lignite, peat). The urgent goal is to curb the exponential increase in the concentration of carbon dioxide in the atmosphere and hydrosphere (Figures 1.1 and 1.2) that is directly related to our consumption of fossil carbon for our energy and materials The goal of the Paris agreement (United Nations COP 21, Dec. 12, 2015) of limiting the temperature increase to 1.5 degrees (compared to the pre-industrial era, before 1800) is becoming increasingly unattainable (Intergovermental Panel on Climate Change (IPCC), report of Aug. 6, 2021). On Aug. 9, 2021 Boris Johnson, prime minister of the United Kingdom, declared that coal needs to be consigned to history to limit global warming. CO₂ has an important social cost…

With the gas ionization experiments (Section 1.7) we know that atoms and molecules are made of nuclei and electrons that revolve around them. In this chapter we give representations of these microscopic objects and show how certain atoms or molecular fragments form bonds between them. From the description of the hydrogen atom, the lightest atom in Nature since it contains only one proton and one electron, we will develop a simple model for the bonds between atoms in molecules stable at 25°C. Without making complicated calculations we will be able to predict which bonds between atoms are possible a priori and which structures the molecules containing them have. Atoms are the parts of a Lego® set that can be assembled to make a large number of constructions, but not just any construction (three-dimensional objects with predefined geometries). In Chapter 7, we will develop a slightly more advanced model of the chemical bond. We will examine why some bonds are weaker than others, i.e. which bonds are more or less easily broken by heating…

We have previously hypothesized that density-dependent natural selection is responsible for a genetic polymorphism in crowded cultures of Drosophila. This genetic polymorphism entails two alternative phenotypes for dealing with crowded Drosophila larval cultures. The first phenotype is associated with rapid development, fast larval feeding rates but reduced absolute viability, especially in the presence of nitrogenous wastes like ammonia. The second phenotype has associated with it the opposite set of traits, slow development, slow feeding rates and higher viability. We suggested that these traits are associated due to genetic correlations and that an important selective agent in crowded larval cultures was high levels of ammonia. To test this hypothesis we have examined viability and larval feeding rates in populations kept at low larval densities but selected directly for (i) rapid egg-to-adult development, (ii) tolerance of ammonia in the larval environment and (iii) tolerance of urea in the larval environment. Consistent with our hypothesis we found that (i) larvae selected for rapid development exhibited increased feeding rates, and decreased viability in food laced with ammonia or urea relative to controls, and (ii) larvae selected to tolerate either ammonia or urea in their larval environment show reduced feeding rates but elevated survival in toxin-laced food relative to controls. It would appear that development time and larval feeding rate are important characters for larvae adapting to crowded cultures. The correlated fitness effects of these characters provide important insights into the nature of density-dependent natural selection.

High sensitivity sensing and in-situ monitoring of the ammonia concentration in feedlots could allow for quick acquisition of ammonia information and effective breeding. A laser monitoring system for ammonia was designed based on open-path Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. The system has a millisecond time resolution, and the detection limit is about 5ppm-m. The ammonia concentration of a dairy feedlot in Changshu, Jiangsu Province was monitored in summer. Based on the results, ammonia concentration had a diurnal trend such that it was higher in the daytime than at night. The ammonia concentration increased during the activities of cow feeding and feedlot arranging. It peaked at a value of 5.3ppm at 9:00. In sum, optical technology for ammonia detection with high sensitivity, high time resolution without sampling was used and found to be an effective method for ammonia monitoring in dairy feedlots which provides technical support for scientific breeding.

A novel gas sensor based on cataluminescence (CTL) on the surface of nanosized Ti₂W₃O₁₃ was demonstrated for direct determination of ammonia in air. Trace ammonia was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 105°C to determine. The sensor showed high selectivity to ammonia at wavelength of 540 nm, satisfying activity at temperature of 180°C and good stability at air carrier flow rate of 120 ml/min. The linear range of CTL intensity versus concentration of ammonia was 0.8∼70 mg/m³ (γ=0.9991), and the detection limit (3σ) was 0.5 mg/m³. The recovery of artificial sample was 97.4%—102.5% by this method. There was no response to benzene, SO₂, CO, ethanol and formaldehyde. This sensor allows on-line monitoring of ammonia in air.

In the large COMPASS polarized proton target the 1508 cm³ of irradiated granular ammonia is polarized with the dynamic nuclear polarization method using 4 mm microwaves in 2.5 T field. The nuclear polarization up to 90–93 % is determined with CW NMR. The properties of the observed ammonia proton signals are described and spin thermodynamics in high fields is presented. Also the second moment of the NMR line is estimated.