Use Of Ethylene Research Articles

Electrochemical Characteristics of Discrete, Uniform, and Monodispersed Hollow Mesoporous Carbon Spheres in Double‐Layered Supercapacitors

Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size.

Ethylene influences in vitro regeneration frequency in the FR13A rice harbouring the SUB1A gene

Many studies have examined the effects of ethylene on in vitro plant growth and development, often with controversial results. Ethylene accumulates in culture vessels due to both the release from the tissues and the physical entrapment due to the need for closed containers. This hormone has several effects on plant regeneration, depending on the plant species and even the cultivar. A prerequisite for ethylene use for in vitro culture is thus to formulate a specific protocol for the genotype of interest. In rice, ethylene is a key regulator of adaptation strategies to low oxygen environments. In particular, the SUBMERGENCE1A (SUB1A) gene, when present, drives the acclimation response which when activated by ethylene produced by submerged plants leads to adaptation through reduced plant growth and ethanolic fermentation enhancement. This gene is restricted to a limited number of rice for which a very specific response to ethylene is expected, whatever the source. This paper reports the regeneration differences between a SUB1A rice landrace (indica-aus, FR13A) and a non-SUB1A variety (japonica, Nipponbare). Our results suggest that regeneration protocols with exogenous ethylene precursors supply are required for the FR13A rice harbouring the SUB1A gene to overcome the problem of low regeneration efficiency.

Evidence of wettability variation on carbon nanofiber layers grown on oxidized silicon substrates

This paper describes how layers of carbon nanofibers (CNFs) with a controllable wettability can be synthesized by means of thermal catalytic chemical vapor deposition on nickel-based thin films on oxidized silicon supports. In order to achieve well-adhesive CNF-layers with a uniform surface coverage and tunable wettability without the necessity of post-synthesis treatments, a series of synthesis parameters is investigated: the pretreatment atmosphere (hydrogen or oxygen; 2h, 500°C), the use of ethylene (C2H4) or an ethylene/hydrogen (C2H4/H2) mixture as hydrocarbon source, and the growth time (in the range 5–60min).Fast and uniform CNF-growth is found on reduced Ni-based thin films using C2H4/H2 at a synthesis temperature of 635°C. The CNF-layers on Ni are superhydrophobic or highly hydrophobic for all growth times, but their adhesion to the support is poor for growth times >30min. In contrast, the adhesion of CNF-layers on Ni/Ta is excellent. Moreover, the wettability of these as-synthesized CNF-layers can be controlled by variation of the growth time: from superhydrophobic (⩽10min) to hydrophilic (⩾50min). CNF-layers with such tunable wettability can be easily integrated in flow channels of silicon-based microfluidic systems, thereby offering numerous applications.

High density polyethylene and poly(ethylene terephthalate) in situ sub-micro-fibril blends as a matrix for wood plastic composites

Wood plastic composites were prepared based on in situ formed poly(ethylene terephthalate) (PET) sub-micro-fibril reinforced high density polyethylene (HDPE) matrices, using a two-step reactive extrusion technology. The use of ethylene–glycidyl methacrylate (E-GMA) copolymer improved phase compatibility in the sub-micro-fibril blends (SMFBs) with 75% HDPE and 25% PET. Most of in situ formed PET fibrils were less than 500 nm in diameter. The PET fibrils obviously increased mechanical properties of the blend, especially the moduli. The subsequent addition of 40 wt.% wood flour did not influence the size and morphology of PET fibrils, and the fibrils and wood fibers had a synergic reinforcement effect on composite properties. Compared with the HDPE/wood composites, the SMFB/wood system had 65% higher tensile strength, 95% higher tensile modulus, 42% higher flexural strength, and 64% higher flexural modulus, respectively. The technology offers a way to use engineering plastics (i.e., PET) for high performance WPC manufacturing.

Synthesis, Growth Mechanism, and Electrochemical Properties of Hollow Mesoporous Carbon Spheres with Controlled Diameter

Hollow mesoporous carbon spheres with controllable diameters have been fabricated from core–shell structured mesoporous silica sphere templates using chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres with different diameters are obtained. The use of ethylene as the carbon precursor produces mesoporous graphitic hollow carbon spheres. The hollow carbon spheres have a relatively large degree of graphitization together with good meso-structural order and high specific surface area of 771 m2/g. The mechanism governing the formation of the hollow spheres is studied, and the importance of the surfactant (CTAB) is also clarified. CTAB accelerates the carbon deposition process, thus improving the product yield. These hollow carbon spheres that have good electrochemical properties are suitable for lithium ion batteries.

Pós-colheita de lichia 'Bengal' tratada com etileno e 1-metilciclopropeno

Objetivou-se determinar as respostas fisiológicas e bioquímicas associadas ao uso de etileno e 1-metilciclopropeno (1-MCP) na conservação pós-colheita de lichias, assim como a influência desses tratamentos isolados ou combinados no escurecimento desses frutos. Após a colheita, foram aplicados os seguintes tratamentos: sem aplicação de 1-MCP ou etileno; etileno (20µL L-1, por 6 horas); 1-MCP (300nL L-1, por 12 horas) e etileno (20µL L-1, por 6 horas) + 1-MCP (300nL L-1, por 6 horas). Após os tratamentos, os frutos foram armazenados a 5°C e 90% UR durante 30 dias, sendo avaliados a cada 10 dias (+3 dias de comercialização simulada a 25°C e 65% UR). Avaliou-se a produção de etileno, taxa respiratória, sólidos solúveis (SS), perda de massa fresca, coloração (luminosidade - L* e a*) e atividade da polifenoloxidase (PPO). A produção de etileno e taxa respiratória não apresentaram diferenças significativas entre os tratamentos e os SS decresceram ao longo do armazenamento, mas também sem diferenças entre os tratamentos. A atividade da enzima PPO foi aumentada, sendo correlacionada com os índices decrescentes de L* e a* presentes nos frutos, ocorrendo, paralelamente, aumento da perda de massa dos frutos. Conclui-se que o escurecimento do pericarpo da lichia está relacionado à perda de massa fresca e aumento da atividade da PPO e que nenhum dos tratamentos utilizados evitou o escurecimento dos frutos.

Gas-phase flame synthesis and properties of magnetic iron oxide nanoparticles with reduced oxidation state

Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane.

Microstructural Polymer Design through Coordinative Polymerization of Semi‐Crystalline Poly‐1‐Olefins

AbstractThe polymer micro structure of poly(butene‐1) can be designed by the introduction of comonomers like ethylene (poly(ethylene‐co‐butene‐1)) as well as the dedicated use of special polymerization catalysts. With the use of ethylene as comonomer the change of polymer micro structure also leads to changes in the macroscopic material parameters leading to polymers with a new application profile which are of special interest as hot melt adhesive raw materials. The use of dedicated polymerization catalysts allows the production of new poly(butene‐1) hot melt adhesive raw materials without the use of additional comonomers.

Advanced approach to polycyclics by a synergistic combination of enyne metathesis and Diels–Alder reaction

Enyne metathesis (EM) has widely been used to prepare various synthetic and natural products. Further, a sequential use of EM and Diels-Alder (DA) reactions generates highly functionalized and intricate polycarbocycles and heterocyclic frameworks. In this critical review we describe the application of a unique combination of EM and DA reactions to prepare various amino acid derivatives, natural products and heterocycles. Some of the heterocyclic targets include cyclic peroxides, siloxanes and various nitrogen (or oxygen) containing compounds. Use of ethylene and cyclooctadiene (COD) for improving the yield of EM products are also discussed (69 references).

Study of banana (Musa aaa Cavendish cv Nanica) trigger ripening for small scale process

The present work focuse on the impact of O2, CO2 and ethylene concentrations on ripening rate control of bananas as a contribution for the development of domestic equipments that could allow the user to drive the fruit shelf live. It represented the adjustment of metabolic activity rates in order to manage the maturity process. Ripening variables such as ethylene and CO2 concentrations and temperature were adjusted to accelerate or slow down the process, while the maturity degree was monitored through the physical and chemical parameters and sensorial analysis. Therefore, the objective of this work was to evaluate the influence of these parameters to manage the banana ripening. The optimum temperature was at 25 ºC of storage. The presence of oxygen, CO2 withdraws and ethylene injection were relevant for the ripening process. The "ready-to-eat" quality was achieved in 6 days in confined system. The use of ethylene as trigger was adequate to accelerate the ripening process with advantages in fruit color.

Evaluating stepping displacements of pedestrian concrete pavements connected by EPDM rubber and PVC joiners

Pedestrian concrete pavements (sidewalks) are usually made of continuous slabs with simple control joints at a specified interval. Simple control joints such as breaking score lines or saw cuts are created on the pedestrian concrete pavements mainly to relieve stresses resulting from friction and also to avoid displacement/unplanned cracking. However, these joints have no load transfer mechanism and therefore the concrete slab panels may have different vertical movements at the joint when the pavements are affected by tree root invasion or by soil movement. Such differential vertical movements at adjoining slabs can create tripping hazards to pedestrians. This paper presents the use of ethylene–propylene–diene terpolymer (EPDM) rubber and polyvinyl chloride (PVC) joiners for minimizing such tripping hazards. An experimental investigation for evaluating stepping displacements of concrete pavements connected by EPDM rubber and PVC joiners has been undertaken. Nonlinear finite element analysis models using ABAQUS have also been developed.

Tandem Action of Early−Late Transition Metal Catalysts for the Surface Coating of Multiwalled Carbon Nanotubes with Linear Low-Density Polyethylene

The homogeneous surface coating of multiwalled carbon nanotubes with linear low-density polyethylenes, containing from 3 to 34 branches per 1000 carbon atoms, has been achieved for the first time by combining the polymerization-filling technique (PFT) with tandem copolymerization catalysis. This method, which takes advantage of the use of ethylene as single monomer feed, allows for the breakup of the native nanotube bundles and provides an effective way to control the branching in the PEs produced at the nanotube surface. TEM micrographs of the composite materials have shown an interesting dependence of the PE-coating morphology on the experimental parameters of the tandem system.

Papaya Fruit Ripening: Response to Ethylene and 1-Methylcyclopropene (1-MCP)

Ripening affects the quality and nutritional contents of fleshy fruits, and papayas are climacteric fruits very susceptible to postharvest losses due to the fast softening caused by ethylene. This paper reports the changes in respiration, ethylene production, and pulp color and firmness, along with the contents of soluble sugars and major carotenoids, during ripening of 'Golden' papaya, an important Brazilian cultivar that has been exported to North American and European markets. The results obtained for nontreated and ethylene- or 1-MCP-treated papaya suggest that 1-MCP can decrease the quality of treated fruit and that even the use of ethylene for triggering or inducing homogeneous ripening can result in lower quality when compared to that of fruit allowed to ripe naturally.

All-Carbon Quaternary Centers via Catalytic Asymmetric Hydrovinylation

The highly enantioselective construction of an all-carbon stereocenter at the benzyl position has been accomplished. Using nickel catalysis with phosphoramidite ligand 1, the authors achieved high yields (over 90% in most cases), high selectivities (>95% for the benzyl position) and high ee values (>90% in most cases). The reaction proceeds at low temperature (-60 °C to -70 °C) and is complete within 4-14 hours. The use of ethylene as the vinyl source is also extrememly efficient.

RESPIRATORY AND STORAGE BEHAVIOR OF FRESH CUT ´TOMMY ATKINS´ MANGO

The respiratory and storage behavior of fresh cut 'Tommy Atkins' mango, naturally ripened (NR) or with use of ethylene (RE), were studied. Fruits were selected, washed and disinfected (200 mgCl.L -1 ) and stored for 12 hours at 10°C. After this period, they were processed under hygienic conditions at 10°C, packaged in polyethylene terephthalate (PET) trays or in styrofoam trays wrapped with stretchable polyvinyl chloride (PVC) film and stored for up to 15 days at 3°C. The products were evaluated regarding the evolution of internal atmosphere in the packing (O 2 and CO 2 ), development of weight, appearance, shelf life and consumer acceptability. The respiratory rate was measured before and after processing every two hours. The yield of 'Tommy Atkins' mango to produce fresh cut product was 48.09±0.95%. Increase of the respiration rate of both mango samples was verified one hour after the preparation (NR = 17.75 mL CO 2 .kg -1 .h -1 ; RE = 28.29 mL CO 2 .kg - 1 .h -1 ), followed by stabilization at 3.76 and 8.07 mL CO 2 /kg.h, respectively. The percentage of O 2 in packages was stable in all treatments, 15-20% in PVC trays, 18-20% in PET tray. The percentage of CO 2 was steady around 1.5-2.5%. The products lost fresh mass during the storage, from 0.06% to 0.30% for PET trays and from 0.15% to 1.61% for trays covered with PVC. The appearance was considered appropriate for commercialization until the 13 th day, whereas product from mangoes ripened with application of ethylene was for 11 days, presenting browning in the external surface. The naturally ripened mango presented the best flavor and consumer preference in relation to the mango ripened with application of ethylene for 11 days of storage. The control of hygienic conditions during the production and storage was good and with safety for until 10 days.

Efficient Synthesis of α-C-Galactosyl Ceramide Immunostimulants: Use of Ethylene-Promoted Olefin Cross-Metathesis

[reaction: see text] Olefin cross-metathesis has been used to prepare alpha-C-galactosylceramide derivatives. The metathesis process merged vinyl and propenyl glycosides with vinyl derivatives of phytosphingosine. The use of ethylene enhanced the yield of the methathesis step.

Chemical vapor deposition boron carbo–nitride deposited using dimethylamine borane with ammonia and ethylene

Amorphous boron carbo–nitride films, BCxNy, (0.05⩽x⩽1.51,0.05⩽y⩽0.67), were deposited on SiO2 at 360°C and 1Torr using dimethylamine borane [NH(CH3)2:BH3] with ammonia and/or ethylene. The film composition could be controlled by varying the flow of ammonia and ethylene. X-ray photoelectron spectroscopy indicated a change in bonding environments, increasing the B–N bonding with the addition of ammonia and increasing B–C and C–C bonding with the addition of ethylene. The film dielectric constant, k, was 4.62 without coreactant, decreased to 4.11 by adding ammonia and 3.66 upon adding ethylene. The index of refraction ranged from 2.069 to 1.826 with correlation to k depending on the coreactant added. The root mean square surface roughness ranged from 0.30to0.65nm, increasing with the use of ethylene. A 1μm film deposited at 3.60°C using C2H4 had a hardness of 8.7GPa and modulus of 71.3GPa.

Organosolv pulping of olive tree trimmings by use of ethylene glycol/soda/water mixtures

Abstract This paper reports on the influence of independent variables in the ethylene glycol/soda pulping of olive wood trimmings (165–195°C, 30–90 min, ethylene glycol concentration 5–15%, soda concentration 2.5–7.5% and liquid/solid ratio 4–6), on the yield and Kappa index of the pulps and the strength properties (breaking length, burst index and tear index) of paper sheets. By using a central composite factorial design, equations that relate each dependent variable to the different independent variables were obtained which reproduced the experimental results for the dependent variables with errors less than 12%. Using a temperature of 184°C, ethylene glycol and soda concentrations of 15% and 7%, respectively, a liquid/solid ratio of 5:1 and a cooking time of 30 min results in yield, Kappa index, breaking length, burst index and tear index values that depart by 14.3%, 8.2%, 17.1%, 17.0% and 2.3%, respectively, from their optimum levels. These conditions result in substantial savings in power consumption and immobilised capital investments as they involve a lower temperature, a lower liquid/solid ratio, and a shorter time than the maximum values tested.

Hydrophobic properties of ethylene–vinyl alcohol copolymer treated with plasma source ion implantation

AbstractThe industrial use of ethylene–vinyl alcohol copolymer (EVOH) film is limited because it is easily degraded by moisture. The plasma source ion implantation (PSII) technique with CF4 or CH4 gas was used for the EVOH film to improve the surface hydrophobic properties. Variables examined in implantation were ion energy (0–10 keV), treatment time (5 s–5 min), and ion species. The hydrophobic properties of EVOH films were greatly enhanced after a CF4 PSII treatment, as evidenced by an increased contact angle from 66° to above 100° at ‐5 keV, and remained relatively unchanged during the period of 28 days. X‐ray photoelectron spectroscopy, atomic force microscopy, and O2 permeability were used to characterize the surface properties of EVOH films treated with PSII. The improved hydrophobic properties were closely related to the formation of fluorine‐containing functional groups such as CF, CF2, and CF3 on the modified surface. The percentage distribution of carbon functional groups supports the role of CF2 and CF3 groups in surface modification. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2069–2075, 2004

The Role of Carbon Precursor in Boron Carbide Synthesis by Laser-CVD

This paper focuses on the synthesis of rhombohedral B4C (r-B4C) coatings by CO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive atmosphere of BCl3, H2 and CH4 or C2H4. The influence of the carbon precursor on the deposition kinetics is discussed. The use of ethylene as carbon precursor presents several advantages over the use of methane, which is the conventional carbon precursor in CVD processes. These advantages are mainly related to its high absorption coefficient at the laser wavelength and a higher sticking coefficient, which enables to attain higher deposition rates and film thickness control at lower carbon precursor concentration. Films with carbon content from 15 to 22 at.% were grown at a deposition rate as high as 0.12 ∝m.s -1 .