Ppm Ethylene Research Articles

Detailed experimental and kinetic modeling study of toluene/C2 pyrolysis in a single-pulse shock tube

Abstract A combined experimental and kinetic modeling study is carried out to explore the influences of acetylene and ethylene addition on the species formation from toluene pyrolysis. Experiments are conducted separately with four different argon-diluted binary toluene/C2 mixtures in a single pulse shock tube at a nominal pressure of 20 bar over a temperature range of 1150−1650 K. All the experimental mixtures contain about 100 ppm toluene and different amounts of C2 fuels (50, 216, 459 ppm acetylene and 516 ppm ethylene). Species concentrations as a function of the temperature are probed from the post-shock gas mixtures and analyzed through the gas chromatography/gas chromatography-mass spectrometry techniques. A kinetic model is developed, which successfully predicts the absolute species concentration measurements as well as the changes brought by the varied fuel compositions. With the neat fuel decomposition profiles as a reference, both fuel components exhibit increased reactivity in the pyrolysis of all studied binary mixtures, indicating the existence of obvious synergistic effects. In particular, such effects become more remarkable when increasing the initial acetylene concentration. This essentially results from the addition-elimination reaction of a toluene fuel radical and a C2 fuel molecule leading to a C9 molecule and a hydrogen atom. Indene is identified as the predominant C9 product in all studied cases, and its peak concentrations sharply increase with the initial acetylene contents in toluene-acetylene pyrolysis. On the other hand, indane, produced from the addition-elimination reaction between benzyl and ethylene, is only detected at trace levels in toluene/ethylene pyrolysis. This indicates a relatively weaker interaction between benzyl and ethylene, compared to that of benzyl and acetylene. Apart from the increased concentrations of hydrogen atoms and C9 aromatics, interactions between toluene and C2 fuels also directly result in a reduced level of C7 radicals in the reaction system. Overall, PAH species can be divided into two groups according to the way their peak concentrations varying with the initial fuel compositions. For those largely depending on benzyl reactions, such as bibenzyl, biphenylmethane, fluorene and phenanthrene, the peak concentrations decrease with the added C2 fuels. In contrast, increasing trends are observed in the peak concentrations of the PAHs which rely on indenyl as a precursor, including naphthalene, methyl-indene, benzofulvene and acenaphthalene.

Quality maintenance of broccoli by the use of 1-MCP treatments

AbstractBroccoli's high perishability and its sensitivity to negative quality changes (i.e., mass loss, ethylene induced degreening, abscission of leaves, and florets) generates quality problems during postharvest. Freshly harvested samples were stored at 5 and 21 °C after separately treated for 24 h with 625 ppb 1-methyl-cyclopropene (1-MCP), 24 h with 2 ppm ethylene and 1-MCP followed by ethylene. Quality maintenance effectivity of 1-MCP was investigated during cold and room storage by non-destructive optical methods (chlorophyll fluorescence and DA-index®) and by the evaluation of the visual physiological symptoms. The highly positive effects of 1-MCP treatment combined with cold storage were obviously proven on quality maintenance providing better retention of initial quality related to the initial mature green stage as chlorophyll content related DA-index®; Fm, Fv, Fv/Fm, and Fm/F0 chlorophyll fluorescence values. From the practical point of view, the rapid, and easy-to-use Sintéleia FRM01-F Vis/NIR DA-meter® could be applied relatively easy for the quality measurement of broccoli. The reproducibility of quality determination could be increased by the enhanced number of measuring points or using computer aided imaging methods (i.e., chlorophyll fluorescence imaging, machine vision system) providing global and more reliable information about quality changes.

Water-Resistant Pt Sites in Hydrophobic Mesopores Effective for Low-Temperature Ethylene Oxidation

The structure–activity relationship of silica-supported Pt catalysts in aerobic oxidation of 50 ppm ethylene was studied at 0 °C with a fixed-bed flow reactor and in situ characterization technique...

Pathogenesis and Persistence of Increased Epithelial Mucosubstances in the Nasal Airways of Rats and Mice Episodically Exposed to Ethylene.

Rats repeatedly exposed to high airborne concentrations of ethylene develop eosinophilic rhinitis and mucous cell hyperplasia/hypertrophy (MCH) in nasal respiratory epithelium. Mechanisms underlying these lesions are not well understood to inform occupational exposure guidelines. In this study, we determined (1) the nasal histopathology in rats episodically exposed to ethylene, (2) the ethylene-induced nasal histopathology in similarly exposed mice, and (3) how innate lymphoid cells (ILCs) play a role in ethylene-induced MCH. Animals were exposed to 0 or 10,000 ppm ethylene, 6 h/d, 5 d/wk, for 2 weeks and sacrificed 1 day or 2 weeks postexposure. Others received three 2-week exposure blocks separated by 2-week intervals of no exposure. Episodic exposure was chosen to aid in distinguishing irritant from immune responses. Mucous cell hyperplasia/hypertrophy was induced by ethylene in both species. Rats developed a mild, but transient, eosinophilic rhinitis. Mucous cell hyperplasia/hypertrophy was transient in mice, but persistent in rats. Increases in epithelial mucosubstances after 2 weeks of exposure were only present in ILC-sufficient mice, but not in ILC-deficient mice suggesting that ILCs play a role in MCH and overexpression of genes associated with mucus production/secretion. These findings in animals suggest that inhaled ethylene does not act as a sensitizing agent and will not induce allergen-like nasal airway disease.

Highly sensitive and selective ethylene gas sensors based on CeOx-SnO2 nanocomposites prepared by a Co-precipitation method

CeOx-SnO2 nanocomposites (NCs) with different Ce:Sn compositions of 0:100, 20:80, 25:75, 33:67, 50:50 and 100:0 were synthesized via a two-reactant co-precipitation method. The phase, morphology, particles size, elemental composition and chemical state of as-prepared CeOx-SnO2 nanoparticles (NPs) were characterized by X-ray diffraction, nitrogen adsorption, electron microscopy and X-ray spectroscopy. The results revealed that the highly crystalline solid solution phases structure of CeOx-SnO2 were formed exhibiting approximately round morphologies with average particles sizes of ~5–20 nm. The sensor properties towards ethylene gas were characterized in terms of response, response times, stability and selectivity. The gas-sensing data showed that the addition of CeOx to SnO2 provided significant enhancement of ethylene response and the CeOx-SnO2 NPs (Ce:Sn = 33:67) offered the highest response of 5.18 with a short response time of 12 s to 10 ppm ethylene at 350 °C. Additionally, the sensor exhibited a low minimum detectable ethylene concentration of 0.3 ppm, high ethylene selectivity and good stability. Therefore, the sensor based on coprecipitated CeOx-SnO2 NPs could ce a promising candidate for detection of ethylene in fruit-ripeness monitoring applications.

Rough SmFeO3 nanofibers as an optimization ethylene glycol gas sensor prepared by electrospinning

In this study, perovskite samarium ferrite (SmFeO3) nanofibers have been successfully fabricated by electrospinning route and calcination process. The as-prepared sample was characterized by various technologies. The results show that the surfaces of SmFeO3 nanofibers are of extreme depression and roughness, which increases contact area between gases and material surface, contributing to enhancing gas sensing properties. The sensor based on as-prepared SmFeO3 nanofibers owns good response and distinct selectivity to ethylene glycol, and response value reaches 18.19 to 100 ppm ethylene glycol at 240 °C, even to 5 ppm ethylene glycol with high response value of 2.18. In addition, the gas sensing mechanism based on hole accumulation layer model was explained in detail.

The application of zinc oxide layer as ethylene sensor

As an emerging n-type semiconductor, ZnO has been widely applied in sensor area. In this study, we prepared an ethylene sensor using ZnO layer on FTO glass substrate. The seed layer was deposited using simple electrodeposition method using voltage of -1.1 V for 2 hours in cold bath (6°C). The ZnO layer was further grown using CBD technique at 90°C for 2 hours. In order to observe the effect of structural manipulation on the sensor performance, some of the ZnO layer samples were undergoing hydrothermal treatment at 100ºC for 1 hour under 1 bar N2 gas. After annealing process, all ZnO layers were exposed with 50 ppm ethylene gas in closed chamber. Based on the results, it is shown that the optimum ZnO layer has been successfully identified the ethylene gas in concentration of 50 ppm, with response value of 2.40% at 200°C.

Exploring cold quarantine to mango fruit against fruit fly using artificial ripening

Mango quarantine is based mainly on heat treatment, with a possible deterioration of fruit quality. We studied the effects of cold quarantine (19 days storage at 2 °C) on fruit quality of commercial mango cvs. Keitt and Shelly for three consecutive years. Chilling injury (CI) occurs in mango fruit stored at temperatures lower than 12 °C. By reanalysing our previous transcriptome, we found that under sub-optimal temperature storage (5 °C), the fruit increases its ethylene biosynthesis and osmolarity by activating sugar metabolism, thereby probably reducing its freezing point. Similarly, ripe fruit with higher sugar concentration should be more resistant to cold-storage stress. Here, mango fruit was artificially ripened with 150 ppm ethylene. The control group, stored at 2 °C, suffered from severe CI, whereas the combined treatment of artificial ripening, modified atmosphere (fruit were enclosed in perforated bags) and subsequent low-temperature conditioning resulted in a significant reduction in CI to satisfactory levels for consumer acceptance (taste, aroma and texture). The combined treatment reduced lipid peroxidation and maintained flavour, leading to a novel cold-quarantine treatment for mango fruit. Thus, by reversing the supply chain and storing ripe and ready-to-eat fruit, cold quarantine was enabled for mango, and possibly other chilling-susceptible fruits.

Optimization of process parameters for banana ripening using ethylene gas

The study on organic ripening of banana (Musa sp. var ‘Robusta’) fruit was carried out to optimize the best suitable combination of ethylene concentration, temperature and relative humidity. Process parameters were optimized using the design-expert version 8.0.6 software (Stat-Ease Inc, Minneapolis, USA) and applying factorial methodology to the experimental data. Quality parameter of well ripen banana were taken as standard for comparing the experimental results. The temperature, relative humidity, ethylene gas concentration and duration of ripening were observed to have profound influence on ripening characteristics of banana fruit. Among all, the combination of 40°C temperature, 80% relative humidity and 90 ppm ethylene concentration was found optimum for producing ripening effect after 72 hours with quality parameters i.e. total soluble solid (17.68%), pH(4.79), L*(60.26) a* (12.35) and b* (37.73) which were very close to values of standard sample. The study concluded that ripening of banana can be performed with the help of ethylene gas in closed chamber within three days.

2D SnO2 Nanosheets: Synthesis, Characterization, Structures, and Excellent Sensing Performance to Ethylene Glycol.

Two dimensional (2D)SnO2 nanosheets were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide in a mixed solvent of absolute ethanol and deionized water at a lower temperature of 130 °C. The characterization results of the morphology, microstructure, and surface properties of the as-prepared products demonstrated that SnO2 nanosheets with a tetragonal rutile structure, were composed of oriented SnO2 nanoparticles with a diameter of 6–12 nm. The X-ray diffraction (XRD) and high-resolution transmission electron microscope (FETEM) results demonstrated that the dominant exposed surface of the SnO2 nanoparticles was (101), but not (110). The growth and formation was supposed to follow the oriented attachment mechanism. The SnO2 nanosheets exhibited an excellent sensing response toward ethylene glycol at a lower optimal operating voltage of 3.4 V. The response to 400 ppm ethylene glycol reaches 395 at 3.4 V. Even under the low concentration of 5, 10, and 20 ppm, the sensor exhibited a high response of 6.9, 7.8, and 12.0 to ethylene glycol, respectively. The response of the SnO2 nanosheets exhibited a linear dependence on the ethylene glycol concentration from 5 to 1000 ppm. The excellent sensing performance was attributed to the present SnO2 nanoparticles with small size close to the Debye length, the larger specific surface, the high-energy exposed facets of the (101) surface, and the synergistic effects of the SnO2 nanoparticles of the nanosheets.

Ethylene, 1-MCP and the Antitranspirant Effect of Active Compound-Film Forming Blend

Pot plant production in greenhouse is most of the time under high relative humidity and frequent irrigation, whereas during shipment and retailing plants may be exposed to high temperature and infrequent irrigation. These unfavorable conditions often cause water loss, desiccation of plants and short shelf life. To reduce the deteriorating effect of water loss, application of antitranspirants is one of the integral measures to take. In the first experiment, we evaluated the antitranspirant effect of two physiologically active gaseous compounds Ethylene and 1-MCP (1-methylcyclopropane) and their interaction with the successful active compound ABA (Abscisic acid). In the second experiment, with the aim of discovering a more potent antitranspirant, we evaluated the efficacy of an active compound-film forming blend. Excised leaves of Spathiphyllum sweet checo were sprayed with different preparations. Weight loss (transpiration) as gram of water per gram of initial leaf weight and stomatal conductance were measured. In the first experiment, 10 ppm Ethylene and 500 ppb 1-MCP found to reduce water loss conspicuously and negatively interacted with 1.5 mM ABA. In the second experiment, a potent mixture of active compound-film forming antitranspirants: ABA 1.5 mM + Leaf Shine 1:20 followed by SA (Salicylic acid) 5 mM + Leaf Shine 1:20 and SNP (Sodium nitroprusside) 200 µM + Leaf Shine 1:20 were discovered. In both experiments, significant positive correlations were found between weight loss and stomatal conductance (R= 0.975, 0.987, P<0.05).

The Analysis of β-cryptoxanthin and Zeaxanthin using HPLC in the Accumulation of Orange Color on Lowland Citrus

Citrus peel color is one of the main quality attributes which was caused by the accumulation of carotenoids and its derivatives, especially β-citraurine. It makes citrus peel color looks attractive (orange). The orange color is a mixture of β-cryptoxanthin with β-citraurin. The objectives of this study were (1) to observe the effect of precooling and duration of proper ethylene exposure in the formation of orange color on citrus peel, (2) to identify and determine the β-cryptoxanthin content and total chlorophyll on citrus peel. Citrus was from Tuban, East Java while the study was conducted at PKHT IPB and LIPI. Precooling and without precooling treatment prior to injection of 100 ppm of ethylene exposed at 15 °C, duration of exposure control (0), 24, and 48 hours. The results show that the best color of the Citrus Color Index (CCI) is the precooling treatment and the duration of ethylene exposure for 24 hours, which can reduce total chlorophyll content about 8 times and proved to increase β-cryptoxanthin pigment content five times in accelerating the formation of orange citrus reticulata peel color to bright orange. Degreening has no significant effect on total dissolved solids and the firmness level of citrus fruits.Keyword: β-cryptoxhantin; citrus; chlorophyll; degreening; ethylene zeaxanthin.

Effect of ethylene on physiological changes during ripening of mango (Mangifera indica L.) Cv. Kesar

The mango fruit Cv. Kesar were exposed to ethylene gas (100 ppm) for 12, 18 and 24h in fruit ripening chamber (29.4-31.9oC. with 65-84 % R.H.) and the untreated fruit was kept at ambient temperature (26-30oC with 54-62% R.H.). The fruits were then removed from the ripening chamber at the end of exposure period, packed in corrugated fibreboard boxes and then kept at ambient condition to study the ripening behaviour. In ethephon dip treatments, the mango fruits were treated with ethephon at the concentration of 500,750 and 1000 ppm for five minutes, drained, packed in corrugated fibreboard boxes and then kept at ambient condition. It was found that mango Cv. Kesar exposed to the ethylene gas in the ripening chamber and ethephon dip treatment triggered the ripening process. It was observed that mango fruits Cv. Kesar ripened by exposing them to 100 ppm ethylene gas in ripening chamber for 18 hrs and storage at ambient condition recorded the maximum shelf life of 6 days and showed better results in respect of high overall acceptability score of 8.77. Similarly, mango fruits Cv. Kesar ripened by ethephon dip treatment of 750 ppm for 5 minutes and storage at ambient condition recorded the maximum shelf life of 8 days and showed better results in respect of high overall acceptability score of 8.66, respectively. The cost of ripening chamber for 800 kg fruits on per day interest and ethylene gas was considered for calculating the cost of ripening. The cost was found to be Rs 0.69 per kg.

A physiologically based toxicokinetic model for inhaled ethylene and ethylene oxide in mouse, rat, and human

Ethylene (ET) is the largest volume organic chemical. Mammals metabolize the olefin to ethylene oxide (EO), another important industrial chemical. The epoxide alkylates macromolecules and has mutagenic and carcinogenic properties. In order to estimate the EO burden in mice, rats, and humans resulting from inhalation exposure to gaseous ET or EO, a physiological toxicokinetic model was developed. It consists of the compartments lung, richly perfused tissues, kidneys, muscle, fat, arterial blood, venous blood, and liver containing the sub-compartment endoplasmic reticulum. Modeled ET metabolism is mediated by hepatic cytochrome P450 2E1, EO metabolism by hepatic microsomal epoxide hydrolase or cytosolic glutathione S-transferase in various tissues. EO is also spontaneously hydrolyzed or conjugated with glutathione. The model was validated on experimental data collected in mice, rats, and humans. Modeled were uptake by inhalation, wash-in–wash-out effect in the upper respiratory airways, distribution into tissues and organs, elimination via exhalation and metabolism, and formation of 2-hydroxyethyl adducts with hemoglobin and DNA. Simulated concentration-time courses of ET or EO in inhaled (gas uptake studies) or exhaled air, and of EO in blood during exposures to ET or EO agreed excellently with measured data. Predicted levels of adducts with DNA and hemoglobin, induced by ET or EO, agreed with reported levels. Exposures to 10000 ppm ET were predicted to induce the same adduct levels as EO exposures to 3.95 (mice), 5.67 (rats), or 0.313 ppm (humans). The model is concluded to be applicable for assessing health risks from inhalation exposure to ET or EO.

Ethylene detection using TiO2–WO3 composite sensor for fruit ripening applications

PurposeThe purpose of this paper was to develop a chemo-resistive sensor based on TiO2–WO3 composite material to detect and estimate ethylene released from the fruit ripening process to ensure food safety.Design/methodology/approachThe ethylene sensor has been fabricated using TiO2–WO3 composite material through the sol-gel method.FindingsThe sensitivity of the sensor obtained using the pre-calibrated ethylene is found to be 46.2 per cent at 200 ppm ethylene concentration, and the proposed sensor could measure 8 ppm as the lowest concentration.Originality/valueThe sensor was tested for continuous ethylene detection during natural ripening of fruits and hence is useful for ensuring food safety through discrimination of the type of fruit ripening. A TiO2–WO3 composite ethylene sensor is developed for the first time.

The Triple Response Assay and Its Use to Characterize Ethylene Mutants in Arabidopsis.

Exposure of plants to ethylene results in drastic morphological changes. Seedlings germinated in the dark in the presence of saturating concentrations of ethylene display a characteristic phenotype known as the triple response. This phenotype is robust and easy to score. In Arabidopsis the triple response is usually evaluated at 3 days post germination in seedlings grown in the dark in rich media supplemented with 10 μM of the ethylene precursor ACC in air or in unsupplemented media in the presence of 10 ppm ethylene. The triple response in Arabidopsis consists of shortening and thickening of hypocotyls and roots and exaggeration of the curvature of apical hooks. The search for Arabidopsis mutants that fail to show this phenotype in ethylene or, vice versa, display the triple response in the absence of exogenously supplied hormone has allowed the identification of the key components of the ethylene biosynthesis and signaling pathways. Herein, we describe a simple protocol for assaying the triple response in Arabidopsis. The method can also be employed in many other dicot species, with minor modifications to account for species-specific differences in germination. We also compiled a comprehensive table of ethylene-related mutants of Arabidopsis, including many lines with auxin-related defects, as wild-type levels of auxin biosynthesis, transport, signaling, and response are necessary for the normal response of plants to ethylene.

Humidity Effects on Physiological Quality of Stored Tomatos and Bananas

Tomatoes harvested at both green and pink stages of maturity and bananas harvested at the three quarter green mature stage were stored at 20°C and relative humidity of 62%, 78% and 94% until full ripening. Bananas ripening was initiated by exposure to 10 ppm ethylene for 24 h at beginning of the study. The number of days to ripe, skin colour, firmness, titratable acidity, total soluble solid and weight loss of fruits were measured. The organoleptic characteristic of bananas was also evaluated. Ripening time was shorter in banana than in tomato; and in pink tomatoes than in green tomatoes. Whereas increasing air RH increased ripening time of tomatoes with less water loss and without effect on fruit color; the reverse was true in banana where ripening time was reduced with less weight loss, less firm and good eating quality fruits of high soluble solids content and flavor despite of the less yellow peel colour. Fruit firmness was in general higher in green than in pink tomatoes and in both it was maximum at medium RH; while that of bananas was maximum at low RH. The concentration of total soluble solids was about 4 times higher in bananas than in tomatoes; and in the latter it was comparable in pink and green tomatoes. Total soluble solids were non-significantly affected by RH in pink tomatoes; but peaked at medium RH in green tomatoes and bananas. Titratable acidity was comparable in pink and green tomatoes and was non-significantly affected by RH in pink tomatoes but increased by increasing RH in green tomatoes. Weight loss during storage was in general higher in bananas than in tomatoes and in both species it exhibited progressive decrease with the increase in RH with stronger effect in bananas than in tomatoes.

An electrochemical model for prediction of microvia filling process

The microvia filling process as encountered in the multi-layered printed circuit board manufacturing industry was investigated by electrochemical measurement and a multi-physics coupling technique in this paper. The effect of an accelerator on filling performance was investigated by cathode polarisation curves to obtain the suitable copper electroplating conditions. In the model, mass balance of adsorbed additives as a result of cathode surface shape change was considered. The electrodeposited layer thickness in the microvia from the additive-free solution and additive-assisted solution was calculated by the finite element method. The void-free microvia filling was finally achieved in acid copper electroplating solution consisting of base electrolyte, 200 ppm ethylene oxide–propylene oxide co-polymer and 1 ppm bis-(sodium-sulphopropyl)-disulphide, which was validated by experimental results.

Ethylene pre-harvest application in ‘Cabernet Sauvignon’ produced in the region of “Dom Pedrito” – RS

Thus this work was to evaluate the use of ethylene application in pre-harvest grapes of Cabernet Sauvignon cultivar. Applying ethylene by spraying with ethylene solution in different periods with the following treatments; (T1) without application of ethylene; (T2) 10 ppm of ethylene in the fruit only on the day of collection; (T3) two applications of 10 ppm ethylene (one day before harvest and once on the day of harvest) and; (T4) three applications of 10 ppm ethylene (two days prior to harvest, one day prior to harvest and the other on the day of harvest). For each treatment were made four replications in the field, with 07 plants each. The physicochemical analyses in must and wine as pH, total soluble solids (TSS), expressed acidity malic acid, expressed as acid into lactic acid, total acid and ethanol were made by infrared spectrometry Fourier transform (FTIR). There were significant differences between treatments in physical and chemical composition of must and wine. These preliminary results suggest that ethylene pre-harvest application modify somehow the malic acid content, modifying the total acidity and pH of the must and wine in Cabernet Sauvignon, promoting a slight modification in the TSS and thus in ethanol.

Proteomic analysis of differentially expressed proteins involved in ethylene-induced chilling tolerance in harvested banana fruit.

To better understand the mechanism involved in ethylene-induced chilling tolerance in harvested banana fruit, a gel-based proteomic study followed by MALDI-TOF-TOF MS was carried out. Banana fruit were treated with 500 ppm ethylene for 12 h and then stored at 6°C. During cold storage, the chilling tolerance was assessed and the proteins from the peel were extracted for proteomic analysis. It was observed that ethylene pretreatment significantly induced the chilling tolerance in harvested banana fruit, manifesting as increases in maximal chlorophyll fluorescence (Fv/Fm) and decreased electrolyte leakage. Sixty-four proteins spots with significant differences in abundance were identified, most of which were induced by ethylene pretreatment during cold storage. The up-regulated proteins induced by ethylene pretreatment were mainly related to energy metabolism, stress response and defense, methionine salvage cycle and protein metabolism. These proteins were involved in ATP synthesis, ROS scavenging, protective compounds synthesis, protein refolding and degradation, and polyamine biosynthesis. It is suggested that these up-regulated proteins might play a role in the ethylene-induced chilling tolerance in harvested banana fruit.