Synthetic Air Research Articles

Optical hydrogen sensing with high-Q guided-mode resonance of Al2O3/WO3/Pd nanostructure

Nanostructure based on a dielectric grating (Al2O3), gasochromic oxide (WO3) and catalyst (Pd) is proposed as a hydrogen sensor working at the room temperature. In the fabricated structure, the Pd catalyst film was as thin as 1 nm that allowed a significant decrease in the optical absorption. A high-Q guided-mode resonance was observed in a transmission spectrum at normal incidence and was utilized for hydrogen detection. The spectra were measured at 0–0.12% of hydrogen in a synthetic air (≈ 80% {text{N}}_{2} and 20% {text{O}}_{2}). The detection limit below 100 ppm of hydrogen was demonstrated. Hydrogen was detected in the presence of oxygen, which provides the sensor recovery but suppresses the sensor response. Sensor response was treated by the principal component analysis (PCA), which effectively performs noise averaging. Influence of temperature and humidity was measured and processed by PCA, and elimination of the humidity and temperature effects was performed. Square root dependence of the sensor response on the hydrogen concentration (Sievert’s law) was observed. Sensor calibration curve was built, and the sensor resolution of 40 ppm was found. Long term stability of the sensor was investigated. Particularly, it was shown that the sensor retains its functionality after 6 months and dozens of acts of response to gas.

Sunlight Bleaching of Subporphyrazine Dye Films

Stable subphthalocyanine-type dyes with a high electron affinity attract much attention as potential substitutes for traditional fullerenes in molecular electronics devices. One possible way to enhance the acceptor properties of the subphthalocyanine core is by replacing the peripheral benzene fragments (C6H4) with 1,2,5-thiadiazole fragments (C2N2S1). However, the resistance of these materials to light or atmospheric effect remains an open question, which limits their further application in device manufacturing. In this work, we compare vacuum-deposited films of three derivatives, SubPzS3H0 (all peripheral fragments are 1,2,5-thiadiazoles), SubPzS2H4 (two fragments are 1,2,5-thiadiazoles and one fragment is benzene), and SubPcS0H12 (all benzenes, i.e., parent subphthalocyanine). Practically relevant substrates were used for deposition, namely, bare glass, glass/ITO or FTO, and PET/ITO. Photobleaching of films under continuous 1 sun illumination was studied in laboratory air, synthetic air, and ultrapure argon. It is shown that the exclusion of near-UV photons from the incident light spectrum, which corresponds to the absorption of subphthalocyanines in the Soret-band, strongly inhibits degradation. Absorption in the Q-band range initiates soft annealing rather than photobleaching of films. The stability of the films deposited on glass decreases as SubPzS3H0 > SubPzS2H4 > SubPcS0H12 in air, and vice versa in argon. The substrate adds more complexity to this picture. In argon, the ITO coating reduces degradation of all of the compounds equally, in contrast to the glass samples, while in air, the SubPzS3H0 films discolor completely. The latter reaction proceeds due to the indium-containing species migrating from the conductive coating.

Current distribution and plasma velocity characteristics of parallel-plate accelerator under static pressure

Electromagnetic plasma accelerators which can generate high-density and hypervelocity plasma jets have been widely used in plasma physics research and application fields. An experimental platform of parallel-plate accelerator electromagnetically driven plasma is established in this paper, mainly including a parallel-plate accelerator, a power supply, magnetic probes, photodiodes, a current probe, and an oscilloscope. The current distribution and plasma velocity characteristics of a parallel-plate accelerator under static pressure are studied by using magnetic probe array and photodiode array. The working gas is synthetic air. A mechanical pump is used to pump the vacuum chamber to about 1 Pa, and then synthetic air is injected into the vacuum chamber to a target pressure. The power supply of the parallel-plate accelerator has a sinusoidal oscillation attenuation waveform with a total capacitance of 120 μF and a total inductance of about 400 nH. When the charging voltage is 13 kV, the discharge current is 170 kA and the pulse width is 23.5 μs. The discharge currents are 38, 100, 135 kA, and 170 kA when the pressures are 100, 200, 400 and 1000 Pa, respectively. The current distribution of the parallel-plate accelerator is concentrated, and the discharge mode is consistent with the snowplow mode, when the discharge current is small and the working pressure is high. As the discharge current increases or the working pressure decreases, a diffuse current distribution gradually appears in the parallel-plate accelerator. Two regions are formed, i.e. the plasma front region and the plasma tail region. The diffuse current distribution phenomenon is more remarkable when the discharge current is higher or the working pressure is lower. The plasma front current distribution proportion decreases and the plasma front velocity increases with the increase of discharge current and the decrease of working pressure. However, the plasma velocity proportion increased is much lower than the discharge current proportion increased or working pressure proportion decreased. When the discharge current increases from 38–170 kA, the plasma velocity increases from 25.0 km/s to 33.6 km/s, with the velocity increment being only 34.4%. The plasma front region is subjected to both the Lorentz force and the thermal pressure of the plasma tail region.

Design and application of a paper-based optoelectronic nose for the on-site discrimination of essential oils using a chemometric web app.

Essential oils are appreciated worldwide for their pleasant aroma, in addition to their therapeutic, pharmacological, and cosmetic functions. For these reasons, adulteration is a common practice that decreases product quality causing economic and health issues. In this study, we present for the first time the application of a simple, inexpensive and disposable paper-based optoelectronic nose (i.e. colorimetric sensor array) to (i) discriminate sixteen different types of essential oils and (ii) detect adulterated samples. The colorimetric array was prepared by adding 1.5 μL of 9 chemo-responsive dyes with different chemical properties to each circular spot of the paper-based device. 1 mL of each essential oil was transferred to a flask and bubbled with synthetic air at an airflow of 200 mL min-1. Then, the optoelectronic nose was exposed to the airstream containing the volatiles from the sample for 5 minutes. Digital images from before and after exposure were obtained using a smartphone and the RGB values were extracted using appropriate software. The color changes provided a unique color map fingerprint for each essential oil. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) were successfully employed using a customized smartphone app, showing suitable discrimination of all studied essential oils as well as among adulterated and non-adulterated samples. The proof-of-concept showed the potential of the optoelectronic nose approach for the discrimination of different essential oils and the identification of adulterated samples, providing a valuable tool for quality control procedures.

Graphene oxide and reduced graphene oxide as additives in polysulfone hybrid membranes for gas permeation

Hybrid polymeric membranes with the addition of graphene and derivatives are currently being developed and studied due to the unique properties of this material, whose addition in membranes is related to the enhancement of physical and mechanical properties and separation performance. In this study, polysulfone (PSU) membranes containing graphene oxide (PSU/GO) and reduced graphene oxide (PSU/RGO) were developed at a concentration of 0.5 wt.%, and their morphology, physical-chemical and thermal properties, and separation performance were evaluated. Membrane morphology was evaluated by SEM, thermal stability by TGA/DTG, functional groups and material structure by FTIR, mechanical properties by pressure test, and gas permeation using synthetic air. Agglomeration of GO and RGO was verified, a factor that may have interfered with the performance of the membranes. There was no change in the thermal stability of the membranes with the presence of GO/RGO, nor the occurrence of new bands observed in FTIR spectra, indicating that the interactions between PSU and GO/RGO were physical. All membranes resisted the maximum system pressure (6 bar), and it was not possible to identify whether the addition of graphene-derived materials had a positive effect on the mechanical strength. PSU/GO membranes had a better performance regarding synthetic air permeability in the gas permeation test than PSU and PSU/RGO membranes, possibly due to the functional groups present in GO, which facilitated the mass transfer within the polymer structure.

Redox kinetics of NiO/YSZ for chemical-looping combustion and the effect of support on reducibility

This paper explores the reaction kinetics of NiO supported on YSZ (Yttria Stabilized Zirconia) as an oxygen carrier for chemical looping combustion. Nickel particles with size less than 1 μm mixed with YSZ nano-powders are used to prepare the solid mixture, with 45% mol of NiO. Redox reactivity and oxygen carrying capacity are measured in a laboratory scale fixed bed reactor in the temperature range 500–1000 °C with different concentrations of the reactive gasses. Samples are subjected to repeated redox cycles using synthetic air (O2+Ar) for oxidation, and H2/H2O/Ar mixtures for reduction. NiO/YSZ demonstrates superb cyclic regenerability starting with the 2nd cycle, with full utilization of its oxygen carrying capacity. Compared to pure nickel, pronounced improvement is achieved in the kinetics and oxygen utilization. Full reduction is achieved, and the presence of H2O does not affect the reduction rate. Reactivity is also determined as a function of conversion. Global models of redox conversion are developed, in which surface chemistry and solid diffusion are considered. Oxidation exhibits the characteristics of a shrinking-core model with internal reactions at the Ni/NiO interface being the rate limiting step, and it is weakly temperature dependent. Reduction with H2 generally exhibits surface chemistry limitation (adsorption-desorption), with surface product formation being the rate limiting step. YSZ significantly enhances ionic transport during oxidation and reduction. Reaction rate dependencies on conversion during the two steps suggest an optimal range for the oxygen carrying capacity of the material.

Learning Adaptive Probabilistic Models for Uncertainty-Aware Air Pollution Prediction

The air pollution problem has been a serious issue for public health and city development in recent years, which rises an urgent demand for accurate air pollution prediction models. Traditional time series prediction scheme has been challenged in such case because the air pollution signals can be highly dynamic and uncertain. Distinct latent physical processes and complex environment changes over time make it hard for one fixed model to give consistently good performance. Also probabilistic prediction and uncertainty-aware estimation are critical when the model is used for public decisions in practice. However, few previous works can simultaneously provide adaptive and probabilistic air pollution prediction abilities, which are important practical issues for the real-world implementation of data-driven air pollution prediction models. In this paper we propose an adversarial meta learning approach to address these concerns. After reformulating the target signals as a collection of independent but similar mini-tasks along time, we adversarially learn a meta model that includes an implicit generator to adaptively give more informative probabilistic predictions across tasks. We further provide a bayesian meta learning interpretation that recasts the proposed model as an approximate minimizer for the Wasserstein distance between a generative latent model and the true data distribution. Our model provides an algorithm that explicitly models how the prediction distribution is conditioned on underlying data patterns and simultaneously gives adaptive uncertainty estimation. Experiments on both synthetic and real-world air pollution datasets show that the proposed model can simultaneously provide better probabilistic and adaptive prediction while keeping stratifying point prediction error.

Hydrogen absorption of ultra-high strength aluminum-silicon coated 22MnB5 steels

The hot forming process allows to produce safety-relevant structural components in the automotive industry with strengths of 1500 MPa and higher. Generally, high strengths make material sensitive to hydrogen embrittlement. The heat treatment in the hot forming process chain is a potential source of diffusible hydrogen for hot-dipped aluminum-silicon coated boron-manganese steels. In the present work, the influence of different process gases and furnace dwell times during the heat treatment was investigated. Humidified process gases such as synthetic air, nitrogen, oxygen and carbon dioxide were used. The results of the thermal desorption mass spectrometry (TDMS) revealed a more pronounced hydrogen uptake for nitrogen and carbon dioxide gas atmosphere than for synthetic air and oxygen. Furthermore, different material conditions were investigated regarding their sensitivity to hydrogen absorption. The flat-rolled material tends to suffer a higher hydrogen absorption compared to the reference material when using humidified process gases. Materials being pretreated with dry synthetic air point at a relation between the duration time of the pretreatment and the content of absorbed hydrogen.

Multi‐Functional Cu‐BTC and ZIF‐67 Grown Chitosan Air Filters for Efficient NO and Particular Matter Removal

AbstractZeolitic imidazolate framework‐67 (ZIF67) or copper(II)‐benzene‐1,3,5‐tricarboxylate (CuBTC)‐based chitosan fibers grown in situ on fibers can be used in the development of effective air filters. In this context, herein, metal–organic frameworks (ZIF67 or CuBTC) are grown in situ on chitosan fibers (denoted as C‐ZIF67 or C‐CuBTC), and the NO gas adsorption performance, particular matter filtration efficiency, and antibacterial properties of the fabricated materials against E. coli and S. epidermidis are investigated. The specific surface areas of C‐ZIF67 and C‐CuBTC are 311.9 and 140.1 m2 g−1, respectively, whereas that of the untreated chitosan fibers is 0.1 m2 g−1. For C‐ZIF67, the NO adsorption efficiency rapidly increases up to 78%; specifically, 70% adsorption is maintained for 65 min. For C‐CuBTC, the NO adsorption efficiency rapidly increases up to 54% initially and substantially decreases to 41% after 10 min. Furthermore, C‐ZIF67 exhibits a 3.4 times higher NO adsorption capacity than that of C‐CuBTC. For C‐ZIF67 and C‐CuBTC, the filtration efficiencies against PMs are higher than 99%. However, C‐CuBTC shows a higher antibacterial activity (99.99%) against E. coli and S. epidermidis compared to C‐ZIF67. The C‐ZIF67 and C‐CuBTC, derived from renewable resources, can be good alternatives for commercial synthetic air filters because they are biodegradable, cost‐effective, and environment‐friendly.

Rare‐Earth Hydroxometalates Ba[RE(OH)5] with RE=Tb, Dy, Ho

AbstractColorless crystals of the new hydroxometalates Ba[RE(OH)5] with the rare‐earth elements RE=Tb, Dy, Ho were synthesized under ultra‐alkaline conditions in a KOH hydroflux at 200 °C. Single‐crystal X‐ray diffraction revealed that the three compounds crystallize isostructural in the monoclinic space group P21/n (no. 14). In the crystal structure, the rare‐earth cations are coordinated by the oxygen atoms of seven hydroxide anions, which define a distorted pentagonal bipyramid. These polyhedra share edges of their basal ring forming infinite chains that run parallel to the [010] direction. Hydrogen bonds connect the chains into layers parallel to the (101) plane. The Ba2+ cations are located between these layers and surrounded by nine oxygen atoms. Ba[Dy(OH)5] is paramagnetic and shows no luminescence under UV light. When heated in synthetic air or argon, water is released in well‐defined steps. Ba[Dy(OH)5] decomposes via DyOOH to Dy2O3, which then reacts with the remaining Ba(OH)2 to form BaDy2O4. Thus, the hydroxometalates can be used as carbon‐free precursors for oxides.

Thermal properties and decomposition mechanism of disubstituted fused 1,2,4-triazoles considered as potential anticancer and antibacterial agents

Thermal resistance is a very important parameter when assessing the therapeutic usefulness of potential pharmaceutics. Therefore, the thermal behaviour and the decomposition mechanism in the atmosphere of helium and synthetic air of disubstituted fused 1,2,4-triazoles—which may be potential anticancer and antibacterial agents—were studied with a use of simultaneous thermal analysis: thermogravimetry/differential scanning calorimetry (TG/DTG/DSC) coupled online with Fourier transform infrared spectroscopy. It was confirmed that the thermal stability of the tested compounds is directly depended on their structure and thus on the number of chlorine atoms as substituents. The pyrolysis process of disubstituted fused 1,2,4-triazoles in inert conditions runs in two main, non-well-separated stages connected with the emission of NH3, HCN, acetonitrile, aromatics with an OH group, aromatics with a NH2 groups, H2O, CO2 and alkene fragments. However, the thermal stability of those compounds in synthetic air atmosphere is comparable or lower than their thermal stability in helium atmosphere. The decomposition of the tested compounds runs through at least three main stages, resulting in the emission of the same type of volatiles as in inert conditions plus the additional emission of CO and some carbonyl fragments for compounds with no or one chlorine atom as a substituent. The results indicate a simultaneous cleavage of C–N, N–N and C–O bonds during heating of the tested disubstituted fused 1,2,4-triazoles in inert conditions and additional combustion process of pre-formed residues in oxidative conditions.

A comparison of thermo-oxidation kinetic measurements of Zircaloy-4 in light and heavy water steam

High temperature oxidation experiments of Zircaloy-4 have been previously reported using various gaseous environments including light water steam and synthetic air, but no experiments involving heavy water steam oxidation have been reported in the open literature. Understanding the reaction kinetics in heavy water steam is important for CANDU nuclear generating stations, which are moderated and cooled by heavy water. The long standing assumption has been that the oxidation behaviour is the same for both environments; the objective of this work is to validate that assumption. The oxidation behaviour of Zircaloy-4 was investigated in this work under light water steam and heavy water steam to compare the reaction kinetics at temperatures ranging from 500 ∘C to 1250 ∘C to simulate an accident scenario. For this work, a NETZSCH 449 F1 Simultaneous Thermal Analyzer was used to perform thermogravimetric measurements of Zircaloy-4 specimens to measure the mass changes and oxidation reaction rates. A comparison was then drawn and benchmarked to available data in the open literature for similar experiments. Additionally, Scanning Electron Microscopy and Energy-dispersive X-Ray Spectroscopy analyses were performed for a few specimens to analyse and identify oxidation behaviour over the specified temperature range.

A Multivariate Computational Approach With Hybrid Graphene Oxide Sensor Array for Partial Fulfillment of Breath Acetone Sensing

Breath analysis is becoming more prominent in the field of medical science because of its noninvasive nature. In the human breath, there exist thousands of volatile organic components; however, only a limited number are correlated with a specific disease. Acetone is the disease marker for diabetes, and an acetone concentration of more than 1800 ppb in a person’s breath indicates diabetes. In this study, different concentrations of acetone were detected in a dummy exhaled human breath consisting of a large number of interfering volatile organic compounds (VOCs), relative humidity (70%), and synthetic air. An array of six sensors comprised of hybridized graphene oxide (GO) field-effect transistors (FETs) was fabricated and tested for the detection of acetone within the concentration range of approximately 400 ppb to 80 ppm. A GO channel was hybridized with noble metal nanoparticles (NPs) like Au, Pd, and Pt along with WO3 flower-like nanostructures to enhance the acetone selective behavior under suitable back gate voltage in the FET structured sensors. A wide variety of feature vectors were extracted from the sensor data and used via linear discriminant analysis (LDA) and principal component analysis (PCA) to discriminate acetone with different stages of interfaces. Then, the exact acetone concentrations were quantified with a polynomial curve fitting in the sensitivity versus concentration characteristics of all the individual sensors. Acetone concentration in a complex VOC mixture was detected with an average 6.65% relative error by implementing the above technique.

SYNTHESIS AND WOUND HEALING PROPERTIES OF POLYVINYL ALCOHOL FILMS DOPED WITH METAL NANOPARTICLES OF Cu AND Ag

The skin recovery (wound healing) properties of materials based on polyvinyl alcohol (PVA) doped with metal nanoparticles (PVA-MNPs) and their chemical and physical characterization is reported. The synthesis of copper and silver metal nanoparticles supported in PVA was performed by Solvated Metal Atom Dispersed (SMAD) method using 2-ethoxyethanol as solvent. The average size of metal nanoclusters (PVA-Cu = 77 nm, PVA-Ag = 72 nm) was determined by TEM and the distribution of the inorganic phase in the hybrid material was analyzed by SEM-EDX. TGA performed in synthetic air atmosphere shows an improvement in the thermal stability by addition of nanometals to pure polymer, with the copper composite showing a higher thermo resistive capacity than the rest. Antibacterial activity against ATCC bacterial strains of Escherichia coli (E.C.), Staphylococcus aureus (S.A.), Staphylococcus epidermidis (S.E.) and Pseudomonas aeruginosa (P.A.) was determined. The silver compound showed antibacterial activity against all tested microorganisms, while the copper compound was active against S.E. Toxicological and wound healing tests were performed in Sprague Dawley rats with infested injuries on the back which were treated with PVA films doped with copper and silver. The recovery of injures infested with S. aureus is reported. This type of material could be used for biomedical applications, such as skin recovery processes in infected wounds or type I and II burns.

Systematic Review on Respiratory Toxicology Caused by Synthetic Air Fresheners

Abstract: The main objective of this comprehensive review research on the various kinds of respiratory illness caused by the synthetic air fresheners. Air fresheners are widely used in indoor built environmental settings such as businesses, schools, residences, transit, hotels, hospitals, care facilities, and a variety of private and governmental structures. In order to create a comfortable indoor atmosphere, air fresheners are made to add aroma to the air or to cover up odours. Air fresheners, however, can produce and emit a variety of potentially toxic air pollutants that can deteriorate air quality, regardless of their intended use. Volatile organic compounds (VOCs) found in air fresheners include ones that may be harmful air pollutants, carcinogens, or substances linked to adverse health consequences including asthma, COPD and so on. Air fresheners have been identified as a major source of volatile organic compounds in buildings from the perspective of indoor air quality. Air fresheners have been linked to negative health impacts include neonatal illness, asthma symptoms, mucosal symptoms, migraine headaches, and breathing problems. In this research review we mainly focused on synthetic air freshener, emits various kinds of VOC’s that caused different types of respiratory illness. This review also investigates a paradoxical effect that the synthetic air fresheners meant to enhance indoor environments may also present unanticipated & unidentified risk. Finally, we discussed about the International and National market size of the air freshener.

Oxygen and Carbon Dioxide Separation at Cathodes of Anion Exchange Membrane Cells

From the development of anion exchange membrane fuel cells it is known that airborne CO2 is easily absorbed in this type of membranes and has a detrimental effect on the conductivity of the membrane1. It was also found, however, that at sufficiently high current densities carbonate and hydrogen carbonate ions are flushed out of the membrane and ion conduction occurs predominantly via hydroxyl ions1. This behavior led to the idea of using AEM based cells for gas separation for two different type of applications. So, during the first waves of COVID-19 medical oxygen became a scarce resource. Local production of oxygen by separation from air is an interesting approach to overcome this issue. This should be feasible using an anion exchange membrane cell with an air side oxygen reduction electrode and an oxygen evolution electrode. The hope is that in combination of these two reactions the required cell voltage can be kept much below typical water electrolysis voltages so that operation with simple PV cells or modules is possible. At the same time the question is if current densities can be achieved at which the OH- transport and thus the anodic release of O2 dominates, as an enrichment of CO2 must be avoided for this application. On the opposite there are worries about the effect of increasing CO2 concentration in occupied confined rooms like vehicles. Here a device that removes CO2 from air without consuming much oxygen is desirable. The removal of CO2 from the air supply to AEM fuel cells by an additional cell placed upstream of the cathode inlet and downstream of the anode outlet was demonstrated by Matz at al.2. As for CO2 separation only, no hydrogen is available for the anode reaction here again the operation against an oxygen evolution electrode is required, optimized, however, towards the CO2 transport minimizing O2 transport.In this study for one type of AEM membrane and ionomer, namely Fumapem FAA3 and Fumion (both Fumatech BWT, Germany) the effect of different cathode electrodes and electrode materials as well as the effect of operation conditions towards the selectivity of oxygen or CO2 transport were investigated. For that purpose, test set-ups were used were the cathode side was supplied with synthetic air, compressed air or synthetic air with added CO2 and the anode side with an inert gas N2 or helium. Nass spectrometry and dedicated CO2 concentration sensors were used to determine the anodic release of O2 and CO2 as well as the reduction of O2 and CO2 concentrations on the cathode side.First measurements of the oxygen transfer using a cell with a silver cathode (Oxag, Gaskatel, Germany) and a nickel foam anode (Gaskatel, Germany) it was found that the oxygen transfer had a promising faradaic efficiency exceeding 80% (cf. Fig. 1). The cell voltage of 1.5 V at 90 mA cm-2 was however still too high for the application. Replacing the Oxag silver electrode by an industrial ORR electrode for alkaline cells did not yield an improvement (cf. fig 2). Increasing humidification to 100 % r.H. improved the current density (cf. Fig 3). Using high humidification conditions, the CO2 effect was studied by switching from synthetic air to pressured air and back and 160 mA cm-2. A rapid increase of the anodic CO2 concentration to values exceeding 2000 ppm was observed (cf. Fig. 4). Comparing CO2 transfer for cells with Oxag cathode and the commercial ORR cathode again showed that the latter would not improve the situation. It proves however, that the CO2 transfer rate can be influenced by the cathode catalyst. Regarding the CO2 separation test with synthetic air with added 3.85 Vol% of CO2 as cathode feed have shown that under such conditions, mainly CO2 is transported (cf. Fig. 5). In total it will be shown that CO2 separation with state-of-the-art materials is already possible. The use of O2 separation regarding onside production of medical O2 today fails due to still too high CO2 selectivity. The fact that CO2 selectivity seems to be dependent on the cathode catalyst may allow further optimization also valuable for AEMFC fuel cell developments.Acknowledgment: The work received financial support in parts from the Fraunhofer-Gesellschaft by the Demo-medVer project part project e3C-O2 as part of the Fraunhofer cs. Corona program. M. Inaba, Y. Matsui, M. Saito, A. Tasaka, K. Fukuta, S. Watanabe and H. Yanagi, Electrochemistry, 79, 322–325 (2011). 2. S. Matz, B. Setzler, C. M. Weiss, L. Shi, S. Gottesfeld and Y. Yan, Meet. Abstr., MA2020-02(34), 2227 (2020). Figure 1

Application of gas nanosensor for detection pheromone and its interferents compounds in vivo Euschistus heros (F.) stink bugs insects

This work aims to apply PANI.Ag cantilever nanosensor to detect volatiles from in vivo E. heros and interfering compounds. The stink bug insects were collected in crops and kept in an environment (chamber) that mimicked the soy culture. The study was carried out with male and female insects together and with male and female insects separated; with interfering compounds from stink bug Diceraeus furcatus; in addition, with synthetic compounds as tridecane and hexenyl (Z)− 3-acetate. The cantilever nanosensor exposed to the volatiles from males and females showed a reduction in the resonance frequency and did not show a response to the volatiles from the chamber that contained only food and water (without insects), and control (synthetic air). The response of the volatiles from the chamber containing female insects was similar to the chamber without insects and was very close to the control. In the chamber containing only males, a reduction in the resonance frequency resulted from the pheromone released by the insects. The resonance frequency did not change considerably when exposed to the volatiles from the environment with D. furcatus , when compared to the control, as well as to tridecane and hexenyl (Z)− 3-acetate compounds. Thus, the gas nanosensor was able to distinguish the volatile compounds released by male E. heros , making it a promising alternative for agriculture in integrated pest management. • Detection pheromone compounds from E. heros insects in vivo with nanosensor . • Volatile molecules from E. heros males and females. • The resonance frequency did not change when exposed to interferent compounds. • Agriculture integrated pest management.

The impact of the synthesis temperature on SnO2 morphology and sensitivity to CO2 under in-field conditions

The impact of the synthesis temperature on SnO 2 morphology and sensitivity to CO 2 under in-field conditions • SnO 2 is obtained by hydrothermal method, at different synthesis temperatures. • SnO 2 crystalline nanoparticles are faceted, with regular morphologies. • Main crystallographic planes (0 0 1), (1 0 1), (1 1 0) contain oxygen positions. • The sensing properties are evaluated under in-field conditions, RH = 0–50 %. • CO 2 concentration varies between 400 and 5000 ppm CO 2 . This letter highlights the role of synthesis temperature over the morpho-structural properties of SnO 2 . Specific crystalline nanoparticles with quasi-tetragonal and quasi-hexagonal morphologies are faceted, suggesting a high reactivity to atmospheric oxygen. This is a premise for the sensing ability of SnO 2 in detecting CO 2 . The in-field conditions are ensured by dynamic synthetic air flow with variable relative humidity, a wide range of CO 2 concentrations and potential interfering gases at their specific detection limits.

Optimization of thermal characteristics of axisymmetric synthetic air jet impingement on flat surface

The local heat transfer of axisymmetric synthetic air jet impinging on flat surface is investigated experimentally. Acoustic speaker is used for generation of synthetic air jet with cavity of cylindrical shape.The experiments is conducted for actuator frequency ranging from 50Hz to 400Hz, orifice diameter 2mm to 10mm, orifice plate thickness 2mm to 10mm, cavity diameter 50mm to 75mm, cavity depth 30mm to 60mm, jet to plate distance 16mm to 112mm. A steady heat flow is maintained on the flat surface. Local heat transfer characteristics on flat surface is found by thermal images using IR thermal imaging and thin foil technique.The experimental results reveals that the heat transfer is highly effected by frequency, orifice diameter, orifice plate thickness, jet to plate distance. However, cavity depth and cavity diameter has small influence on thermal performance.The higher cavity volume show more influence on heat transfer characteristics. An optimization of synthetic jet performance parameters is studied for maximum thermal performance interms of heat transfer characteristics.

Ag(μ‐en)][ReO4]: An Intermediate during Preparation of the Ethylene Epoxidation Catalyst

AbstractPreparation of a catalyst for the ethylene oxide production requires impregnation of a porous corundum support with an aqueous silver ethylene diamine oxalate complex solution, to which among others NH4[ReO4] is added. Here we report on [Ag(μ‐en)][ReO4] that precipitates from such a mixture. Single crystal structure analysis has revealed a striking similarity of the [Ag(μ‐en)]+ entity with the same complex cation encountered in[Ag(μ‐en)]2(C2O4)×2H2O. Silver is coordinated end‐on to the nitrogen atoms of the en ligands. The [ReO4]− anions are not bonded to the silver cations, but instead involved in N−H⋅⋅⋅O hydrogen bonds to the ethylene diamine molecules. The first step of thermal degradation occurs at approximately the same temperature for both, the main component precipitate [Ag(μ‐en)]2(C2O4)×2H2O and [Ag(μ‐en)][ReO4], warranting proximity of the rhenium promoter and the elemental silver deposit. At 300 °C, the temperature at which the catalyst for EO synthesis is commonly calcined, the decomposition product of plain [Ag(μ‐en)][ReO4] under synthetic air is Ag[ReO4], in full analogy to industrial manufacturing process for selected Re‐promoted EO catalyst formulations.