Ammonia Gas Concentration Research Articles

Detection of Kidney Complications Relevant Concentrations of Ammonia Gas Using Plasmonic Biosensors: A Review

Kidney-related health problems cause millions of deaths around the world annually. Fortunately, most kidney problems are curable if detected at the earliest stage. Continuous monitoring of ammonia from exhaled breath is considered as a replacement for the conventional blood-based monitoring of chronic kidney disease (CKD) and kidney failure owing to its cost effectiveness, non-invasiveness, excellent sensitivity, and capabilities for real-time measurement. The detection of ammonia for renal failure requires a biosensor with a detection limit of 1000 ppb (1 ppm). Among biosensors, plasmonic biosensors have attracted considerable research interest due to their potential for ultra-sensitivity, single particle/molecular level detection capability, multiplexing capability, photostability, real-time measurement, label-free measurement, room temperature operation, naked-eye readability, ease of miniaturization via simple sensor chip fabrication, and instrumentation, among other features. In this review, plasmonic sensors for the detection of ammonia gas relevant to kidney problems (LOD ≤ 1 ppm) are reviewed. In addition, the utilized strategies and surface functionalization for the plasmonic sensor are highlighted. Moreover, the main limitations of the reported sensors are stated for the benefit of future researchers. Finally, the challenges and prospects of plasmonic-based ammonia gas biosensors for potential application in the monitoring and screening of renal (kidney) failure, as well as the endpoint of the dialysis session, are stated.

Exploring PEDOT:PSS interaction with hazardous gas molecules in microwave regime using organic microwave resonators

Organic electronics have offered an interdisciplinary solution for the development of modern electronics that are flexible, affordable, easy to implement, and eco-friendly. This paper outlines the design and implementation of an organic microwave resonator (OMR) where the conventional metallic trace was replaced by an intrinsically conducting polymer: poly (3,4 ethylenedioxythiophene):poly(styrene sulfonate), known as PEDOT:PSS. Owing to this conducting polymer’s reversible doping/dedoping properties in reaction with electron-donating gases, the proposed organic resonator was implemented to monitor ammonia gas, as a proof of concept. PEDOT:PSS patterned in a split-ring configuration operates in the C-band (i.e., 4 GHz to 8 GHz) with a resonant frequency of 4.93 GHz and resonant amplitude of −23.74 dB. The large active surface area stemming from the entire ring resonator made of PEDOT:PSS yielded excellent detection sensitivity (9.4 mdB/ppm) and repeatability (<5% variation) to enable the detection of low concentrations of ammonia gas (limit of detection of 1.3 ppm). Moreover, the device demonstrated high selectivity to ammonia gas with negligible sensitivity (<0.1 dB) observed to 1000 ppm of various interferant gases (acetone, ethanol, isopropyl alcohol, and methanol). This study demonstrates the significant potential of organic microwave resonators for the development of the next generation of low-cost, printable, and passive microwave resonators that can be made wearable and flexible for a wide variety of applications.

Preparation and characterization of Titanium oxide-composite polymers

Two types of monomers polyindole and poly m-aminophenol were used to prepare conducting copolymer with use FeCl3 as an initiator by using chemical polymerization. The prepared polymers were characterized using infrared spectroscopy, X-ray scattering, scanning electron microscope (SEM) and thermal analysis TGA. This study was included preparation of copolymers from both monomers in various ratios (1:1, 1:2, 2:1, 1:3, and 3:1) to study the effect of ratios on chemical and physical properties. Moreover, nano-metal oxide (TiO2) (10%) of the weight of the monomers was added to copolymers to synthesis composite polymers. Results of FTIR, SEM and EDX were proved the prepared compounds. TGA findings were showed that composites have remarkably increased of thermal stability. Finally, nano-composite polymers have applied as electrochemical sensor for (NH3) gas. Further, results display that the best sensitivity value is (24.12%) by using copolymer (1mA:3In) (without nano) with response time (7 seconds) and recovery time (3 seconds). Furthermore, results show that prepared nanocomposites have highly sensitive features with fast responses time even within a low concentration of ammonia gas at 25° C. The highest sensitivity value (79.14%), response time (3 seconds) and recovery time (3 seconds) was recorded when used nanocomposite titanium oxide (TiO2) at the ratio (1mA:3In).

The effect of synergistic interaction of ceria-doped copper oxide prepared by hydrothermal method as toxic gas sensor

The effect of introducing cerium oxide (CeO2) at 5% and 9% concentrations as dopants to improve the catalytic performance of the copper oxide (CuO) nanoparticles was studied using a hydrothermal technique. The seed layer is placed in an autoclave, usually made of Teflon, and heated with water for 10 hours at 100°C. The resulting films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence (PL). The grain size decrease as the doping concentration increases, while the roughness, and RMS increase. The sensor was developed to detect different concentrations of ammonia (NH3) gas. CuO at 9% of CeO2 sample exhibited the highest sensitivity about (48%) for NH3 gas at 1.5C.

Gas-Mediated Immunoassay for the Carcinoembryonic Antigen at Atmospheric Pressure with Smartphone Coupling with the Fluorescence Quenching Length of Perovskite Capillary

By combining the photothermal properties of the 3,3',5,5'-tetramethylbenzidine oxidation product (TMBox) with the sensitive quenching of perovskite fluorescence by ammonia gas, a gas-mediated immunoassay at atmospheric pressure was constructed, which took the fluorescence quenching length of perovskite fluorescent capillary as the signal output. First, a CsPbBr3 perovskite with surface modification of 3-aminopropyl triethoxysilane was synthesized by thermal injection and decorated to the capillary wall by glutaraldehyde cross-linking. In the presence of H2O2 and the tumor marker carcinoembryonic antigen (CEA), TMB was oxidized to TMBox by the horseradish peroxidase (HRP)-labeled CEA antibody. The photothermal effect of TMBox at 808 nm laser irradiation increases the concentration of ammonia gas, and the prepared fluorescent capillary can respond sensitively to ammonia gas. The fluorescence quenching length can be observed by the naked eye for a semiquantitative evaluation of CEA concentration. At the same time, we developed a mobile APP for the first time to measure the fluorescence quenching length. In the range of 0-20 ng mL-1, the quenching length increased linearly with the increase in CEA concentration, and the detection limit was 0.078 ng mL-1. This method has been successfully used for the detection of CEA in human serum with a recovery of 95.8%-106.5%.

RANCANG BANGUN SISTEM PEMBERSIH KOTORAN OTOMATIS PADA KANDANG KELINCI BERBASIS IOT (INTERNET OF THINGS)

Rabbits have their charm for breeding because of the benefits they get from rabbits. However, rabbit farming has a fairly high challenge, namely rabbits die easily because of the cleanliness of the cage. The accumulation of rabbit droppings results in increased levels of ammonia gas which are harmful to rabbits, breeders, and even the environment. In cleaning the cage, rabbit breeders still use manual methods that are ineffective and inefficient. For this reason, a systemwas created to create an automatic feces cleaning system in the rabbit cage based on IoT (Internet of Things) by utilizing loadcell sensors to detect the weight of rabbit droppings that are accommodated on the conveyor belt. Belt conveyor as a medium that transports rabbit droppings. The MQ-135 sensor is used to detect the concentration of ammonia gas and the MCUESP8266 Node as a controller and IoT as a notification and as a system control via a smartphone. Based on testing of the system, the loadcell sensor as a measure of the weight of rabbit droppings has an accuracy rate of 97.43%. The MQ-135 sensor as a measure of theconcentration of ammonia gas in rabbit cages has an accuracy rate of 99.19%. The conveyor belt can move to dispose of rabbit droppings when the weight is &gt; 1000 grams or the ammonia gas content is &gt; 25 ppm. Then the Telegram application bot can 100% control the system by inputting commands and can receive notifications from the system. From testing the system as a whole, the system can work according to the desired function with a 100% success rate.

Effect of radiant catalytic ionization on environmental conditions in rodent rooms and the haematological status of mice

High stocking densities, closed animal houses, and elevated concentrations of bacteria, fungi, and the products of their activity, including ammonia and hydrogen sulphide, have adverse health effects. Active techniques used to reduce unfavourable environmental conditions, such as ventilation, sprinkling, bedding sorbents, and nutritional treatments, are not always sufficient to improve the animals’ living environment. The current paper aims to evaluate the effect of radiant catalytic ionization (RCI) on airborne microorganisms, cage microbiological status, gaseous ammonia concentrations, and the haematological status of mice in animal houses. After one week of operation of an RCI system, the number of airborne bacteria and fungi in the experimental room decreased in comparison to the first day of the experiment (p < 0.05 and p < 0.05 respectively), as did the concentrations of ammonia (p < 0.01) and dust. At the same time, the basic health parameters of the mice, determined in the blood, were very similar between the control and experimental room. RCI seems to be an ideal solution to ensure high hygiene standards in animal rooms and houses with limited use of disinfectants or antibiotic treatment of sick animals. An additional, environmental benefit is the limited amount of nitrogen released.

Fabrication and Characterization of P3HT/MoS₂ Thin-Film Based Ammonia Sensor Operated at Room Temperature

The composites of polymers and two-dimensional (2D) materials show promising applications in the area of gas sensing. In this work, we report an efficient ammonia gas (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) sensor based on poly(3-hexylthiophene)/ molybdenum disulfide (P3HT/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanocomposite. The sensing device has been fabricated in bottom-gate top contact organic field-effect transistor (OFET) assembly using P3HT/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as active channel material. The changes in the electrical response of OFET has been measured and analyzed for various ammonia gas concentration at room temperature. The sensing device in the form of an OFET structure is preferred due to multi-parameter characteristics to explore gas sensing applications. The active sensing layer has been fabricated via a self-assembled, cost-effective floating film transfer (FTM) technique. An optimized uniform sensing film of thickness 25±3 nm is used to analyze the change in the electrical characteristic of the device in terms of I/O characteristics, mobility, threshold voltage, trapped charge density, etc., for various ammonia concentrations. The OFET with nanofiber morphology of mobility 0.147 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V-s shows the threshold voltage of −3.78 V (in the air) and changes to −10.71 V after 100 ppm ammonia gas exposure. The device has shown a limit of detection (LOD) of 904 ppb and a sensing response of 63.45% at 100 ppm ammonia concentration. The extraction of multi-parameter sensing characteristics of the device has been conducted in a closed chamber with an ambient environment. The fabricated sensor is therefore having potential applications in high-performance ammonia sensing applications.

Facile preparation of TPU conductive nanocomposites containing polypyrrole-coated multi-walled carbon nanotubes for a rapid and selective response in volatile organic compounds applications

Thermoplastic polyurethane (TPU) conductive nanocomposites were fabricated by using TPU as a matrix and polypyrrole (PPy) coating multi-walled carbon nanotubes (MWCNTs) as conductive filler. The microstructure and gas-sensitive response properties of the nanocomposites to volatile organic vapors (VOCs) were systematically investigated. FTIR and HRTEM verified that PPy was successfully encapsulated on the surface of MWCNTs. FESEM showed that homogeneous dispersion of MWCNTs-g-PPy conductive nanofillers contributed to the formation of continuous conductive networks. The obtained TPU/MWCNTs-g-PPy nanocomposites possessed certain gas-sensitive response selectivity, especially for ammonia gas when compared with other target VOCs. The gas-sensitive response values were in the range of 90–100% with a response time of 40–50 s. An excellent recovery performance at 500 ppm ammonia atmosphere was also achieved. Moreover, the gas-sensitive response values to ammonia showed a good linear relationship with the concentration of ammonia gas. The nanocomposites showed excellent stability in both ammonia and dry-air cycle detection.

New hybrid photonic crystal fiber gas sensor with high sensitivity for ammonia gas detection

A new hybrid photonic crystal fiber (PCF) with circular rings based microstructure core gas sensor has been proposed for detecting ammonia gas at the wavelength of 1.544 μm. The finite element method has been used for numerical investigation. According to the results, the relative sensitivity is obtained as high as 70.25% at a wavelength of 1.544 μm. Furthermore, high birefringence and effective area are acquired by orders of 1.24 × 10−3 and 13.35 μm2, respectively. Finally, a low confinement loss of 1.202 × 10−1 dB/m is gained at the same wavelength. The absorption spectroscopy system can be used for detecting ammonia gas for experimental work. The theoretical results show that the proposed PCF still exhibits high relative sensitivity for a low concentration of ammonia gas at the wavelength of 1.544 μm, which makes the sensors detect gas precisely and can be used for medical and industrial applications.

SnO2 nanomaterial coating micro-fiber interferometer for ammonia concentration measurement

This paper provides a quick and simple method for detecting ammonia gas concentration by coating microfiber interferometer (MFI) with SnO2 sensitive material. The MFI sensor is fabricated by the method of fiber fusion and taper. Then the nanomaterial sensitive to ammonia is prepared by hydrothermal method and coated in the sensing area. When the sensor is in contact with ammonia the SnO2 nanomaterial can adsorb ammonia molecules, which changes the refractive index of the MFI surface and causes the sensor transmission spectrum to shift. The real-time sensing of ammonia concentration can be realized by judging the magnitude of spectral shift. The sensor unit has only optical signal, simple structure, low cost and high sensitivity. The sensor can effectively detect the concentration of ammonia within the range of 0 ppm-10,476 ppm, and the sensor has a sensitivity of 0.58 pm/ppm. The experiment show that SnO2 nanomaterial have high sensitivity to ammonia gas, and the interference sensor coated with SnO2 nanomaterial has good repeatability and selectivity, so it has a broad application prospect in gas sensing in the future.

Multi-sensing dye-doped electrospun polystyrene microfiber mats

In this study, multi-sensing dye-doped electrospun polystyrene microfiber mats were developed. The individual fibers are composed of an inexpensive commodity polymer (atactic polystyrene; aPS) doped with a gas-sensitive dye (bromocresol green; BCG). The fiber mats exhibited outstanding quasi-static direct electromechanical properties, which were enhanced by increasing the doping ratio of BCG. This improvement was attributed to an increase in the real charge density stored in the fiber mats and a decrease in their secant modulus of elasticity. The increase in charge density with increasing BCG doping ratios was attributed to the enhanced conductivity of the electrospinning solution; the decrease in secant modulus was attributed to the decrease in fiber diameter and density of the fiber mats. The BCG-doped aPS fiber mats demonstrated distinguishable color changes even under a low concentration of ventilating ammonia gas (1 ppm). Additionally, the degree of color change increased with an increase in ammonia gas concentration. The proposed multi-sensing microfiber mats can facilitate the development of wearable, lightweight multi-sensors with flexibility and breathability, which, for example, ensure the safety of workers at risk of exposure to harmful gases.

Self-assembled polyaniline nanostructures in situ deposited on silica optical fibers for ammonia gas sensing

Optical fibers coated with polyaniline (PANI) nanostructures were used to sense ammonia gas (NH3) concentration. The PANI nanostructures were synthesized using the oxidative polymerization process in a solution containing poly(methyl vinyl ether-alt-maleic acid) (PMVEA). The PANI nanostructures were in situ deposited on silica optical fibers by immersing the fibers in the solution during the polymerization process for specific durations. The morphology and the thickness of the PANI nanostructure coatings were characterized using Scanning Electron Microscopy (SEM). Raman and Fourier Transform Infra-red (FTIR) spectra confirmed that the PANI nanostructures were in the emeraldine salt (ES) state. The sensors were exposed to various concentrations of NH3 gas at room temperature. The sensor with a coating thickness of 639 nm shows the highest response with a cumulative absorbance response of 2.2 towards 1% NH3 in synthetic air. The response and recovery times are 2.82 min and 11.52 min, respectively.

Ammonia Generation System for Poultry Health Research Using Arduino.

An ammonia gas (NH3) generator was developed to maintain a set concentration of ammonia gas in a controlled environment chamber to study poultry physiological responses to sustained elevated levels of ammonia gas. The goal was to maintain 50 parts per million (ppm) of ammonia gas in a 3.7 m × 4.3 m × 2.4 m (12 ft × 14 ft × 8 ft) controlled environment chamber. The chamber had a 1.5 m3/s (3000 cfm) recirculation system that regulated indoor temperature and humidity levels and a 0.06 m3/s (130 cfm) exhaust fan that exchanged indoor air for fresh outdoor air. The ammonia generator was fabricated by coupling ultrasonic humidifiers with an Arduino-based microcontroller and a metallic oxide MQ-137 ammonia gas sensor. Preliminary evaluation under steady conditions showed the average MQ-137 gas sensor accuracy was within 1.4% of the 65.4 ppm concentration measured using a highly accurate infrared gas analyzer. Further evaluation was performed for a setpoint concentration of 50 ppm where ammonia generator reservoirs were filled with 2% or 10% ammonia liquid. For the system tested, it was found that two generators operating at the same time filled with 3.8 L (1.0 gallon) of 2% ammonia cleaning liquid each (7.6 L or 2.0 gallons total) could maintain a gas level of 49.45 ± 0.79 ppm in the chamber air for a duration of 30 h before refilling was required. One generator filled with 3.8 L of 10% ammonia cleaning liquid could maintain 51.24 ± 1.53 ppm for 195 h. Two ammonia generators were deployed for a six-week animal health experiment in two separate controlled environment chambers. The two ammonia generators maintained an average ammonia concentration of 46.42 ± 3.81 ppm and 45.63 ± 4.95 ppm for the duration of the experiment.

Diurnal evolution of total column and surface atmospheric ammonia in the megacity of Paris, France, during an intense springtime pollution episode

Abstract. Ammonia (NH3) is a key precursor for the formation of atmospheric secondary inorganic particles, such as ammonium nitrate and sulfate. Although the chemical processes associated with the gas-to-particle conversion are well known, atmospheric concentrations of gaseous ammonia are still scarcely characterized. However, this information is critical, especially for processes concerning the equilibrium between ammonia and ammonium nitrate, due to the semivolatile character of the latter. This study presents an analysis of the diurnal cycle of atmospheric ammonia during a pollution event over the Paris megacity region in spring 2012 (5 d in late March 2012). Our objective is to analyze the link between the diurnal evolution of surface NH3 concentrations and its integrated column abundance, meteorological variables and relevant chemical species involved in gas–particle partitioning. For this, we implement an original approach based on the combined use of surface and total column ammonia measurements. These last ones are derived from ground-based remote sensing measurements performed by the Observations of the Atmosphere by Solar Infrared Spectroscopy (OASIS) Fourier transform infrared observatory at an urban site over the southeastern suburbs of the Paris megacity. This analysis considers the following meteorological variables and processes relevant to the ammonia pollution event: temperature, relative humidity, wind speed and direction, and the atmospheric boundary layer height (as indicator of vertical dilution during its diurnal development). Moreover, we study the partitioning between ammonia and ammonium particles from concomitant measurements of total particulate matter (PM) and ammonium (NH4+) concentrations at the surface. We identify the origin of the pollution event as local emissions at the beginning of the analyzed period and advection of pollution from Benelux and western Germany by the end. Our results show a clearly different diurnal behavior of atmospheric ammonia concentrations at the surface and those vertically integrated over the total atmospheric column. Surface concentrations remain relatively stable during the day, while total column abundances show a minimum value in the morning and rise steadily to reach a relative maximum in the late afternoon during each day of the spring pollution event. These differences are mainly explained by vertical mixing within the boundary layer, provided that this last one is considered well mixed and therefore homogeneous in ammonia concentrations. This is suggested by ground-based measurements of vertical profiles of aerosol backscatter, used as tracer of the vertical distribution of pollutants in the atmospheric boundary layer. Indeed, the afternoon enhancement of ammonia clearly seen by OASIS for the whole atmospheric column is barely depicted by surface concentrations, as the surface concentrations are strongly affected by vertical dilution within the rising boundary layer. Moreover, the concomitant occurrence of a decrease in ammonium particle concentrations and an increase in gaseous ammonia abundance suggests the volatilization of particles for forming ammonia. Furthermore, surface observations may also suggest nighttime formation of ammonium particles from gas-to-particle conversion, for relative humidity levels higher than the deliquescence point of ammonium nitrate.

Synthesis of carbon nanostructures using microwave enhanced chemical vapor deposition and its potential application to ammonia sensing

In this paper, Carbon Nanostructures (CNS) were directly synthesized on gallium orthophosphate (GaPO4). An alternative microwave enhanced chemical vapor deposition (MECVD) technique was used to synthesized the CNS via commercial microwave oven with operating power of 600 W at 2.45 GHz. Microwave heating provides the temperature for catalytic decomposition of polyethylene at 750 °C for 4 minutes under atmosperic pressure of 0.81 mbar. Characterization of the as-grown CNS was carried out using Raman spectroscopy and Field Emission Scanning electron microscope (FESEM). Raman spectroscopic investigation reveals the CNS quality of 0.92 and the field emission Scanning electron microscope (FESEM) analysis shows twisted hollow-like CNS structures. The material was deployed as a sensor without any post treatment so as to investigate its potential application in the sensor industry. Different concentrations of ammonia (NH3) gas from 0.06% to 1% were exposed.

Ammonia Gas Sensing Characteristic of P3HT-rGO-MWCNT Composite Films

In this work, the P3HT:rGO:MWCNTs (PGC) nanocomposite film applied to the ammonia gas sensor was successfully fabricated by a drop-casting technique. The results demonstrated that the optimum weight ratio of the PGC nanocomposite gas sensor is 20%:60%:20% as the weight ratio of P3HT:rGO:MWCNTs (called PGC-60). This weight ratio leads to the formation of nanostructured composites, causing the efficient adsorption/desorption of ammonia gas in/out of the film surface. The sensor based on PGC-60 possessed a response time of 30 s, sensitivity up to 3.6% at ammonia gas concentration of 10 ppm, and relative sensitivity of 0.031%/ppm. These results could be attributed to excellent electron transportation of rGO, the main adsorption activator to NH3 gas of P3HT, and holes move from P3HT to the cathodes, which works as charge “nano-bridges” carriers of Multi-Walled Carbon Nanotubes (MWCNTs). In general, these three components of PGC sensors have significantly contributed to the improvement of both the sensitivity and response time in the NH3 gas sensor.

Development of an ammonia gas sensor employing an inter-digital capacitive structure coated with Mn0.5Zn0.5Fe2O4 nano-composite

Sensing toxic gases in the atmosphere is a great challenge since the selectivity of the sensor for the desired gas should be high enough to detect the particular gas at the ppm level. This work presents Mn0.5Zn0.5Fe2O4 nano-composite vacuum deposited over an inter-digital capacitive (IDC) structure as an ammonia gas sensing material. The synthesized material is characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared spectroscopy (FT-IR) to substantiate the crystalline structure and surface morphology of the material. The gas sensing properties of the IDC sensor for ammonia gas are investigated at room temperature. High sensitivity even at extremely low ammonia gas concentrations (of the order of 7 ppm) at room temperature and high selectivity for ammonia gas compared to gases like acetone, ethanol etc., together with low system cost, suggest suitability for developing a new ammonia sensor without using any heating element.

One-pot wet chemical synthesis of reduced graphene oxide-zinc oxide nanocomposites for fast and selective ammonia sensing at room temperature

The present study focuses upon the response of nanocomposites of reduced graphene oxide (rGO) and zinc oxide (ZnO) towards ammonia gas at room temperature. We have synthesized reduced graphene oxide-zinc oxide nanocomposites (rGO-ZnO) by wet chemical route via in-situ one-pot method. The as-synthesized samples were characterized using FT-IR spectroscopy, Raman spectroscopy, X-ray Diffraction, Scanning Electron Microscopy (SEM) and high resolution Transmission Electron Microscopy (HR-TEM) techniques. The average crystallite size of the ZnO sample and rGO-ZnO sample, determined by Williamson-Hall analysis of the XRD results, were calculated to be 20.62 nm and 13.21 nm respectively. The TEM analysis suggests that these nanocomposites comprise of ZnO nanoparticles of average size about 10.8 nm, anchored on rGO sheets. At 300 K, the chemiresistive gas sensing response of pure rGO and rGO-ZnO towards subsequently increasing concentrations (from 20 ppm to 200 ppm) of ammonia gas has been studied. rGO-ZnO samples were prepared by varying the concentration of precursor GO dispersion (0.5, 0.75, 1, 1.25, 1.5 mg/mL). The optimal nanocomposite material (1 mg/mL) is found to exhibit excellent selectivity towards ammonia with a response of 8.92 % towards 20 ppm NH3 and a response time of 8 s. The response is found to increase with increase in ppm level of gas. The selectivity of the synthesized nanocomposite towards ammonia has been confirmed by exposing it to 20 ppm of various other gases such as methanol, ethanol, acetone, propanol and chloroform. The response towards these gases was lower as compared to that towards NH3. To assess the potential of the material in practical applications, the effect of ambient humidity on the sample’s surface resistance was studied. The ammonia sensing response in the presence of humidity was found to vary only by 1.5 % from 10 % RH to 70 % RH, beyond which it saturated. The rGO-ZnO nanocomposite sensing material also displayed good reversibility over subsequent exposure cycles and efficient stability of response with aging. The mechanism of NH3 sensing is understood on the basis of heterojunction interactions between rGO and ZnO in the nanocomposites.

Studies on the concentrations of particulate matter and ammonia gas from three laying hen rearing systems during the summer season

This study aimed to measure the concentrations of particulate matter (PM10, PM2.5) and ammonia gas (NH3) from different types of laying hen houses during summer. The treatment groups included conventional cage, floor pens, and aviary system, with tunnel ventilation system applied to all poultry houses. The PM10 concentration was highest in the aviary system from 10:00 h to 18:30 h, whereas in the cage, it remained high after 18:30 h until 7:30 h the next day. The cage showed high levels of PM2.5 from 18:30 h to 7:30 h the next day. The correlation between the three breeding systems showed an R 2 < 0.2. The mean daily concentrations of PM10, PM2.5, and NH3 were highest in the cage, among all the poultry houses. On comparing the two welfare breeding systems (floor pens and aviary system), particulate matter concentrations were higher in the floor pens, while the aviary system had higher level of NH3. However, no significant differences were observed between the concentrations of PM10, PM2.5, and NH3 between the three laying hen houses in summer. This study provides basic data for improving the rearing environment in the three different types of poultry housing systems.