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Yabing Qi - One of the best experts on this subject based on the ideXlab platform.
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Air Exposure induced dopant redistribution and energy level shifts in spin coated spiro meotad films
Chemistry of Materials, 2015Co-Authors: Zafer Hawash, Sonia R Raga, Yabing QiAbstract:Doping properties of 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD) hole transport layer are investigated by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and atomic force microscopy under Air Exposure. XPS results reveal that 3 h Exposure of Li-bis(trifluoromethanesulfonyl)-imide (LiTFSI) doped spiro-MeOTAD to Air results in the migration of LiTFSI from the bottom to the top across the spiro-MeOTAD film. AFM images reveal the presence of pinholes with an average diameter of ∼135 nm and a density of ∼3.72 holes/μm2. In addition, cross-sectional scanning electron microscope images reveal that these pinholes form channels across the doped spiro-MeOTAD film. Optical microscopy and Fourier transform infrared microscopy images confirm the presence of large pinholes with diameters in the range of 1–20 μm and a density of ∼289 holes/mm2 as well. The presence of pinholes may play a major role in the migration processes of the LiTFSI within the spiro...
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Air Exposure induced gas molecule incorporation into spiro meotad films
Journal of Physical Chemistry Letters, 2014Co-Authors: Philip Schulz, James Endres, Gueorgui O Nikiforov, Yuichi Kato, Antoine Kahn, Yabing QiAbstract:Combined photoemission and charge-transport property studies of the organic hole transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD) under Air Exposure and controlled environments of O2, H2O + N2, and N2 (1 atm and under dark conditions) reveal the incorporation of gas molecules causing a decrease in charge mobility. Ultraviolet photoelectron spectroscopy shows the Fermi level shifts toward the highest occupied molecular orbital of spiro-MeOTAD when exposed to Air, O2, and H2O resembling p-type doping. However, no traces of oxidized spiro-MeOTAD+ are observed by X-ray photoelectron spectroscopy (XPS) and UV–visible spectroscopy. The charge-transport properties were investigated by fabricating organic field-effect transistors with the 10 nm active layer at the semiconductor–insulator interface exposed to different gases. The hole mobility decreases substantially upon Exposure to Air, O2, and H2O. In the case of N2, XPS reveals the incorporation of N2 molec...
Ann-therese Karlberg - One of the best experts on this subject based on the ideXlab platform.
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cinnamyl alcohol oxidizes rapidly upon Air Exposure
Contact Dermatitis, 2013Co-Authors: Ida Niklasso, Tamara Delaine, Nurul M Islam, Roge Karlsso, Kristina Luthma, Ann-therese KarlbergAbstract:Background. Cinnamyl alcohol and cinnamal are frequent fragrance contact allergens. Both are included in the European baseline fragrance mix I, which is used for screening of contact allergy in dermatitis patients. Objectives. The aim of this study was to investigate the autoxidation of cinnamyl alcohol and to identify the oxidation products formed on Air Exposure. We also wanted to evaluate the effect of autoxidation on the sensitization potency of cinnamyl alcohol. Methods. Samples of commercially available cinnamyl alcohol with and without purification were exposed to Air, and the autoxidation was followed by chemical analysis. The analysis was performed with mass spectrometry (LC/MS/MS). Sensitization potencies of compounds were determined with the murine local lymph node assay (LLNA) in mice. Results. Chemical analysis showed that the concentration of cinnamyl alcohol in the Air-exposed samples decreased rapidly over time, and that autoxidation products were formed. Cinnamal, epoxy cinnamyl alcohol and cinnamic acid were identified as oxidation products. According to our study, cinnamal and epoxy cinnamyl alcohol were the first autoxidation products formed. The epoxy cinnamyl alcohol was shown to be the oxidation product with the highest sensitization potency. The analysis of our samples of commercially available cinnamyl alcohol showed that there was already a content of 1.5% cinnamal at the start of the autoxidation experiments. Conclusion. Cinnamyl alcohol readily autoxidizes upon Air Exposure, and forms strong sensitizers as determined by the LLNA. Cinnamal was formed in the largest amounts, showing that cinnamal is not only formed via bioactivation, as has previously been shown. A highly sensitizing epoxide was also identified and quantified in the oxidation mixture.
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lavender oil lacks natural protection against autoxidation forming strong contact allergens on Air Exposure
Contact Dermatitis, 2008Co-Authors: Lina Hagvall, Maria Skold, Johanna Braredchristensson, Anna Borje, Ann-therese KarlbergAbstract:Background: Lavender oil is an essential oil frequently used as a fragrance ingredient and in traditional herbal medicine. We have previously studied the effect of Air oxidation on the skin sensitizing potency of the monoterpenes linalyl acetate, linalool and β-caryophyllene, the main constituents of lavender oil. Objective: The aim of this study was to investigate if the autoxidation observed for the single synthetic terpenes, resulting in strong contact allergens, will take place also in lavender oil. Methods: Lavender oil was exposed to Air and the autoxidation was followed by chemical analysis. The sensitizing potency before and after Air Exposure was investigated in mice using the local lymph node assay. Patients with patch test reactions to oxidized linalool were tested to investigate if Air-exposed lavender oil could elicit dermatitis in these individuals. Results: The terpenes oxidized in Air-exposed lavender oil at the same rates as the pure compounds exposed to Air, and the same oxidation products were identified. The sensitizing potency of lavender oil increased accordingly on Air Exposure. Patch testing showed positive reactions to Air-exposed lavender oil and also to oxidized linalyl acetate in patients with contact allergy to oxidized linalool. Conclusion: This study shows that lavender oil lacks natural protection against autoxidation, and that Air-exposed lavender oil can be an important source of Exposure to allergenic hydroperoxides.
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autoxidation of linalyl acetate the main component of lavender oil creates potent contact allergens
Contact Dermatitis, 2007Co-Authors: Maria Skold, Lina Hagvall, Ann-therese KarlbergAbstract:Background: Fragrances are among the most common causes of allergic contact dermatitis. We have in previous studies shown that linalool, present in lavender oil, autoxidizes on Air Exposure, forming allergenic oxidation products. Oxidized linalool was found to be a frequent cause of contact allergy in a patch test study on consecutive dermatitis patients. Linalyl acetate, the main component of lavender oil is commonly used as a fragrance chemical in scented products. Because of structural similarities, linalyl acetate should also be susceptible to oxidation on Air Exposure, forming similar oxidation products as linalool. Objective: The aim of the present study was to investigate the autoxidation of linalyl acetate and the influence of oxidation on its sensitizing potency. Methods: Analyses were performed using gas chromatography, nuclear magnetic resonance spectrometry and mass spectrometry. Sensitizing potencies of compounds were determined using the local lymph node assay (LLNA) in mice. Results: Analyses showed that the content of linalyl acetate decreased over time on Air Exposure and other compounds were formed. Hydroperoxides, an epoxide and an alcohol were identified as oxidation products from linalyl acetate. In the LLNA, linalyl acetate of high purity showed a weak sensitizing potency (EC3 25%). Autoxidation increased the sensitizing potency of linalyl acetate, and a 10 weeks oxidized sample gave an EC3 value of 3.6%. As for linalool, the hydroperoxides were shown to be the oxidation products with the highest sensitizing potency. Conclusion: It is concluded that autoxidation of the weakly allergenic linalyl acetate leads to formation of allergenic oxidation products.
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fragrance compound geraniol forms contact allergens on Air Exposure identification and quantification of oxidation products and effect on skin sensitization
Chemical Research in Toxicology, 2007Co-Authors: Lina Hagvall, Anna Borje, Carina Backtorp, Sophie Svensson, Gunnar Nyman, Ann-therese KarlbergAbstract:Fragrances are common causes of contact allergy. Geraniol (trans-3,7-dimethyl-2,6-octadiene-1-ol) is an important fragrance terpene. It is considered a weak contact allergen and is used for fragrance allergy screening among consecutive dermatitis patients. Analogous to other monoterpenes studied, such as limonene and linalool, geraniol has the potential to autoxidize on Air Exposure and form highly allergenic compounds. The aim of the present study was to investigate and propose a mechanism for the autoxidation of geraniol at room temperature. To investigate whether allergenic compounds are formed, the sensitizing potency of geraniol itself, Air-exposed geraniol, and its oxidation products was determined using the local lymph node assay in mice. The results obtained show that the allylic alcohol geraniol follows an oxidation pattern different from those of linalool and limonene, which autoxidize forming hydroperoxides as the only primary oxidation products. The autoxidation of geraniol follows two paths, originating from allylic hydrogen abstraction near the two double bonds. From geraniol, hydrogen peroxide is primarily formed together with aldehydes geranial and neral from a hydroxyhydroperoxide. In addition, small amounts of a hydroperoxide are formed, analogous to the formation of the major linalool hydroperoxide. The autoxidation of geraniol greatly influenced the sensitizing effect of geraniol. The oxidized samples had moderate sensitizing capacity, quite different from that of pure geraniol. The hydroperoxide formed is believed to be the major contributor to allergenic activity, together with the aldehydes geranial and neral. On the basis of the present study and previous experience, we recommend that the possibility of autoxidation and the subsequent formation of contact allergenic oxidation products are considered in risk assessments performed on fragrance terpenes.
H Beygi - One of the best experts on this subject based on the ideXlab platform.
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Air Exposure oxidation and photooxidation of solution phase treated pbs quantum dot thin films and solar cells
Solar Energy Materials and Solar Cells, 2019Co-Authors: H Beygi, Seyed Abdolkarim Sajjadi, Abolfazl Babakhani, Jeff F Young, Frank C J M Van VeggelAbstract:Abstract The Air Exposure oxidation mechanisms of PbS quantum dot (QD) thin films and solar cells are studied in the current paper. As a novel and advantageous method, QD thin films were prepared by the single-step deposition of colloidal QDs treated with different ligands of butylamine (BA), mercaptopropionic acid (MPA), tetrabutylammonium iodide (TBAI), methylammonium iodide (MAI) and methylammonium lead triiodide (MAPbI3, perovskite). Photoluminescence (PL) measurements evaluated the stability of different surface treated PbS QDs during the colloidal to thin film transformation, and over the Air Exposure times. Blue-shift and quenching the PL spectra suggested rapid oxidation of QD thin films at the first times of Air Exposure. However, the oxidation rates significantly reduced for the QD thin films treated with organic MPA and all the inorganic ligands. According to the X-ray photoelectron spectroscopy (XPS) studies, thin films oxidation accompanied with the formation of PbSO3 and PbSO4 compounds on the (100) facets of PbS QDs. Although MAPbI3 treatment led to the complete passivation of QDs in the Air, perovskite shelling partially oxidized to PbO and PbCO3 compounds. Furthermore, the PL enhancement phenomenon observed at the first times of Air Exposure for the TBAI and MAPbI3-treated QD thin films, as a result of their strong surface passivation as well as the photoenhancement and photoelectrification mechanisms. Eventually, p-n and p-i-n structured solar cells were fabricated by the single-step deposition of solution-phase treated PbS QD inks. In this case, inorganic surface treatments not only increased the power conversion efficiency (PCE) of solar cells, but also led to a high stability of fabricated devices in the Air environment (lower than 1% PCE loss after 500 h of storage in the Air).
Frank C J M Van Veggel - One of the best experts on this subject based on the ideXlab platform.
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Air Exposure oxidation and photooxidation of solution phase treated pbs quantum dot thin films and solar cells
Solar Energy Materials and Solar Cells, 2019Co-Authors: H Beygi, Seyed Abdolkarim Sajjadi, Abolfazl Babakhani, Jeff F Young, Frank C J M Van VeggelAbstract:Abstract The Air Exposure oxidation mechanisms of PbS quantum dot (QD) thin films and solar cells are studied in the current paper. As a novel and advantageous method, QD thin films were prepared by the single-step deposition of colloidal QDs treated with different ligands of butylamine (BA), mercaptopropionic acid (MPA), tetrabutylammonium iodide (TBAI), methylammonium iodide (MAI) and methylammonium lead triiodide (MAPbI3, perovskite). Photoluminescence (PL) measurements evaluated the stability of different surface treated PbS QDs during the colloidal to thin film transformation, and over the Air Exposure times. Blue-shift and quenching the PL spectra suggested rapid oxidation of QD thin films at the first times of Air Exposure. However, the oxidation rates significantly reduced for the QD thin films treated with organic MPA and all the inorganic ligands. According to the X-ray photoelectron spectroscopy (XPS) studies, thin films oxidation accompanied with the formation of PbSO3 and PbSO4 compounds on the (100) facets of PbS QDs. Although MAPbI3 treatment led to the complete passivation of QDs in the Air, perovskite shelling partially oxidized to PbO and PbCO3 compounds. Furthermore, the PL enhancement phenomenon observed at the first times of Air Exposure for the TBAI and MAPbI3-treated QD thin films, as a result of their strong surface passivation as well as the photoenhancement and photoelectrification mechanisms. Eventually, p-n and p-i-n structured solar cells were fabricated by the single-step deposition of solution-phase treated PbS QD inks. In this case, inorganic surface treatments not only increased the power conversion efficiency (PCE) of solar cells, but also led to a high stability of fabricated devices in the Air environment (lower than 1% PCE loss after 500 h of storage in the Air).
Giorgio Borreani - One of the best experts on this subject based on the ideXlab platform.
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Microbial Dynamics during Aerobic Exposure of Corn Silage Stored under Oxygen Barrier or Polyethylene Films
Applied and Environmental Microbiology, 2011Co-Authors: Paola Dolci, Ernesto Tabacco, Luca Simone Cocolin, Giorgio BorreaniAbstract:The aims of this study were to compare the effects of sealing forage corn with a new oxygen barrier film with those obtained by using a conventional polyethylene film. This comparison was made during both ensilage and subsequent Exposure of silage to Air and included chemical, microbiological, and molecular (DNA and RNA) assessments. The forage was inoculated with a mixture of Lactobacillus buchneri, Lactobacillus plantarum, and Enterococcus faecium and ensiled in polyethylene (PE) and oxygen barrier (OB) plastic bags. The oxygen permeability of the PE and OB films was 1,480 and 70 cm3 m−2 per 24 h at 23°C, respectively. The silages were sampled after 110 days of ensilage and after 2, 5, 7, 9, and 14 days of Air Exposure and analyzed for fermentation characteristics, conventional microbial enumeration, and bacterial and fungal community fingerprinting via PCR-denaturing gradient gel electrophoresis (DGGE) and reverse transcription (RT)-PCR-DGGE. The yeast counts in the PE and OB silages were 3.12 and 1.17 log10 CFU g−1, respectively, with corresponding aerobic stabilities of 65 and 152 h. Acetobacter pasteurianus was present at both the DNA and RNA levels in the PE silage samples after 2 days of Air Exposure, whereas it was found only after 7 days in the OB silages. RT-PCR-DGGE revealed the activity of Aspergillus fumigatus in the PE samples from the day 7 of Air Exposure, whereas it appeared only after 14 days in the OB silages. It has been shown that the use of an oxygen barrier film can ensure a longer shelf life of silage after aerobic Exposure.
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Dry matter and nutritional losses during aerobic deterioration of corn and sorghum silages as influenced by different lactic acid bacteria inocula
Journal of Dairy Science, 2011Co-Authors: Ernesto Tabacco, Federico Righi, A. Quarantelli, Giorgio BorreaniAbstract:The economic damage that results from aerobic deterioration of silage is a significant problem for farm profitability and feed quality. This paper quantifies the dry matter (DM) and nutritional losses that occur during the Exposure of corn and sorghum silages to Air over 14 d and assesses the possibility of enhancing the aerobic stability of silages through inoculation with lactic acid bacteria (LAB). The trial was carried out in Northern Italy on corn (50% milk line) and grain sorghum (early dough stage) silages. The crops were ensiled in 30-L jars, without a LAB inoculant (C), with a Lactobacillus plantarum inoculum (LP), and with a Lactobacillus buchneri inoculum (LB; theoretical rate of 1 × 10(6) cfu/g of fresh forage). The pre-ensiled material, the silage at silo opening, and the aerobically exposed silage were analyzed for DM content, fermentative profiles, yeast and mold count, starch, crude protein, ash, fiber components, 24-h and 48-h DM digestibility and neutral detergent fiber (NDF) degradability. The yield and nutrient analysis data of the corn and sorghum silages were used as input for Milk2006 to estimate the total digestible nutrients, net energy of lactation, and milk production per Mg of DM. The DM fermentation and respiration losses were also calculated. The inocula influenced the in vitro NDF digestibility at 24h, the net energy for lactation (NE(L)), and the predicted milk yield per megagram of DM, whereas the length of time of Air Exposure influenced DM digestibility at 24 and 48 h, the NE(L), and the predicted milk yield per megagram of DM in the corn silages. The inocula only influenced the milk yield per megagram of DM and the Air Exposure affected the DM digestibility at 24h, the NE(L), and the milk yield per megagram of DM in the sorghum silages. The milk yield, after 14 d of Air Exposure, decreased to 1,442, 1,418, and 1,277 kg/Mg of DM for C, LB, and LP corn silages, respectively, compared with an average value of 1,568 kg of silage at opening. In the sorghum silages, the milk yield, after 14 d of Air Exposure, decreased to 1,226, 1,278, and 1,250 kg/Mg of DM for C, LB, and LP, respectively. When the estimated milk yield per megagram of harvested DM of corn and sorghum silage were related to mold count, it was shown that the loss of potential milk production occurred when the mold count exceeded 4 log cfu/g of silage, and it was almost halved when the mold count reached values greater than 8 log cfu/g of silage. Inoculation with L. buchneri, at a rate of 1 × 10(6) cfu/g of fresh forage, enhanced the stability of the silage after Exposure to Air, and, consequently, contributed to maintaining the nutritional value of the harvested forage over time, for Air Exposure up to 7 d.
