-
Materials (Basel, Switzerland) Mar 2022Currently, catalytic processing of biorenewable raw materials into valuable products attracts more and more attention. In the present work, silica-supported FePO and...
Currently, catalytic processing of biorenewable raw materials into valuable products attracts more and more attention. In the present work, silica-supported FePO and Fe-Mo-O catalysts are prepared, their phase composition, and catalytic properties are studied in the process of selective oxidation of propylene glycol into valuable mono- and bicarbonyl compounds, namely, hydroxyacetone and methylglyoxal. A comparative analysis of the main routes of propylene glycol adsorption with its subsequent oxidative conversion into carbonyl products is carried out. The DFT calculations show that in the presence of adsorbed oxygen atom, the introduction of the phosphate moiety to the Fe-containing site strengthens the alcohol adsorption on the catalyst surface with the formation of the 1,2-propanedioxy (-OCH(CH)CHO-) intermediate at the active site. The introduction of the molybdenum moiety to the Fe-containing site in the presence of the adsorbed oxygen atom is also energetically favorable, however, the interaction energy is found by 100 kJ/mol higher compared to the case with phosphate moiety that leads to an increase in the propylene glycol conversion while maintaining high selectivity towards C products. The catalytic properties of the synthesized iron-containing catalysts are experimentally compared with those of Ag/SiO sample. The synthesized FePO/SiO and Fe-Mo-O/SiO catalysts are not inferior to the silver-containing catalyst and provide ~70% selectivity towards C products, while the main part of propylene glycol is converted into methylglyoxal in contrast to the Ag/SiO catalyst featuring the selective transformation of only the secondary C-OH group in the substrate molecule under the studied conditions with the formation of hydroxyacetone. Thus, supported Fe-Mo-O/SiO catalysts are promising for the selective oxidation of polyatomic alcohols under low-temperature conditions.
PubMed: 35269137
DOI: 10.3390/ma15051906 -
The Science of the Total Environment Oct 2021Glycol ethers, such as propylene glycol monomethyl ether (PGME) and propylene glycol monobuthyl ether (PGBE) are solvents found in many professional and domestic...
Glycol ethers, such as propylene glycol monomethyl ether (PGME) and propylene glycol monobuthyl ether (PGBE) are solvents found in many professional and domestic products. In biomonitoring studies, the type of materials used to collect, store, and transport these samples can greatly influence the analytical results because materials can adsorb the analyte. Plastic tubes generally have a hydrophobic internal surface that can reduce the concentration of certain chemicals and result in an underestimation of workers' exposures. The aim of this study was to assess whether the storage of PGME and PGBE spiked blood and urine samples led to different PGME and PGBE concentrations in vials made of glass and common plastics (polypropylene (PP), polyethylene (PE) or polystyrene (PS)). Glycol ether concentrations were quantified with headspace gas chromatography equipped with a flame ionization detector. Our results show stable urinary PGME and PGBE concentrations in PP, while up to 15% variations in urinary PGME for PE and PS. For PGME and PGBE in blood, we observed no statistically significant losses in glass, while losses were recorded for all types of plastic tested (PS, PP and PE). We conclude that biomonitoring samples should be collected in glass for blood and PP for urine.
Topics: Chromatography, Gas; Ether; Ethers; Flame Ionization; Humans; Solvents
PubMed: 34153747
DOI: 10.1016/j.scitotenv.2021.148196 -
Biology of Blood and Marrow... Dec 2020High-dose melphalan (Mel) conditioning before autologous hematopoietic cell transplantation (autoHCT) is standard of care for patients with transplantation-eligible...
High-dose melphalan (Mel) conditioning before autologous hematopoietic cell transplantation (autoHCT) is standard of care for patients with transplantation-eligible multiple myeloma. The traditional lyophilized Mel formulation has inadequate solubility and stability after reconstitution, leading to the use of propylene glycol (PG) as a solubilizing agent. A newer PG-free Mel preparation (Evomela) uses beta cyclodextrin captisol as a solubilizing agent and was approved by the United States Food and Drug Administration as a conditioning agent based on a single-phase IIb study showing bioequivalence. We compared the outcomes of consecutive patients with myeloma undergoing autoHCT using the 2 formulations of Mel for conditioning as our center switched from using the older formulation (PG-Mel) to the newer one (PGF-Mel). Of 294 autoHCT recipients, 162 received PG-Mel conditioning and 132 received PGF-Mel conditioning. The PGF-Mel group was older and had a lower average Karnofsky Performance Status score. PGF-Mel was associated with faster neutrophil recovery (median, 12 days versus 13 days; P < .001), fewer grade 3-4 infections within 30 days of autoHCT (1.5% versus 8.0%; P = .048), and a lower 30-day rehospitalization rate (6.8% versus 17.9%; P = .04), as confirmed by propensity-weighted analysis. No significant between-group differences were detected in mucositis, organ toxicity, myeloma response, or 100-day mortality.
Topics: Hematopoietic Stem Cell Transplantation; Humans; Melphalan; Multiple Myeloma; Myeloablative Agonists; Transplantation Conditioning; Transplantation, Autologous
PubMed: 32920204
DOI: 10.1016/j.bbmt.2020.08.030 -
Toxics Dec 2021It has been demonstrated that propylene glycol (PG), vegetable glycerin (VG), and flavoring chemicals can thermally degrade to form carbonyls during vaping, but less is...
It has been demonstrated that propylene glycol (PG), vegetable glycerin (VG), and flavoring chemicals can thermally degrade to form carbonyls during vaping, but less is known about carbonyl emissions produced by transformation of flavoring chemicals and the interactive effects among e-liquid constituents. This study characterized carbonyl composition and levels in vaping emissions of PG-VG (e-liquid base solvents) and four e-liquid formulations flavored with -2-hexenol, benzyl alcohol, l-(-)-menthol, or linalool. Utilizing gas chromatography (GC)- and liquid chromatography (LC)-mass spectrometry (MS) methods, 14 carbonyls were identified and quantified. PG-VG emitted highest levels of formaldehyde, acetaldehyde, and acrolein. However, flavored e-liquids contributed to the production of a wider variety of carbonyls, with some carbonyls directly corresponding to the oxidation of alcohol moieties in flavoring compounds (e.g., -2-hexenol and benzyl alcohol transformed into -2-hexenal and benzaldehyde, respectively). Detections of formaldehyde-GSH and -2-hexenal-GSH adducts signify interactions of carbonyls with biological nucleophiles. The global reactivity descriptors (, , , , and ) and condensed Fukui parameters (fk0, fk-, fk+, and dual-descriptor) were computed to elucidate site reactivities of selected simple and α,β-unsaturated carbonyls found in vaping emissions. Overall, this study highlights carbonyl emissions and reactivities and their potential health risk effects associated with vaping.
PubMed: 34941780
DOI: 10.3390/toxics9120345 -
Restorative Dentistry & Endodontics Nov 2022This study investigated the cytotoxicity, radiopacity, pH, and dentinal tubule penetration of a paste of 1.0% calcium-doped zinc oxide nanocrystals (ZnO:1.0Ca) combined...
OBJECTIVES
This study investigated the cytotoxicity, radiopacity, pH, and dentinal tubule penetration of a paste of 1.0% calcium-doped zinc oxide nanocrystals (ZnO:1.0Ca) combined with propylene glycol (PRG) or polyethylene glycol and propylene glycol (PEG-PRG).
MATERIALS AND METHODS
The pastes were prepared by mixing calcium hydroxide [Ca(OH)] or ZnO:1.0Ca with PRG or a PEG-PRG mixture. The pH was evaluated after 24 and 96 hours of storage in deionized water. Digital radiographs were acquired for radiopacity analysis and bubble counting of each material. The materials were labeled with 0.1% fluorescein and applied to root canals, and images of their dentinal tubule penetration were obtained using confocal laser scanning microscopy. RAW264.7 macrophages were placed in different dilutions of culture media previously exposed to the materials for 24 and 96 hours and tested for cell viability using the MTT assay. Analysis of variance and the Tukey test ( = 0.05) were performed.
RESULTS
ZnO:1.0Ca materials showed lower viability at 1:1 and 1:2 dilutions than Ca(OH) materials ( < 0.0001). Ca(OH) had higher pH values than ZnO:1.0Ca at 24 and 96 hours, regardless of the vehicle ( < 0.05). ZnO:1.0Ca pastes showed higher radiopacity than Ca(OH) pastes ( < 0.01). No between-material differences were found in bubble counting ( = 0.0902). The ZnO:1.0Ca pastes had a greater penetration depth than Ca(OH) in the apical third ( < 0.0001).
CONCLUSIONS
ZnO:1.0Ca medicaments presented higher penetrability, cell viability, and radiopacity than Ca(OH). Higher values of cell viability and pH were present in Ca(OH) than in ZnO:1.0Ca.
PubMed: 36518610
DOI: 10.5395/rde.2022.47.e38 -
International Journal of Environmental... Nov 2021To investigate passive vaping due to sub-ohm electronic cigarettes (e-cigs), aerosol number size distribution measurements (6 nm-10 µm) were performed during...
To investigate passive vaping due to sub-ohm electronic cigarettes (e-cigs), aerosol number size distribution measurements (6 nm-10 µm) were performed during volunteer-vaping sessions. E-liquids, with vegetable glycerin (VG) and propylene glycol (PG), with a VG/PG ratio of 50/50 (with nicotine) and 80/20 (without nicotine), were vaped with a double-coil, single aerosol exit hole at 25-80 W electric power, corresponding to 130-365 kW m heat fluxes and with an octa-coil, four aerosol exit holes atomizers, at 50-150 W electric power, corresponding to 133-398 kW m heat fluxes. At the lowest heat flux, lower particle number concentrations (N) were observed for the nicotine-liquid than for the nicotine-free liquid, also due to its higher content of PG, more volatile than VG. For the octa-coil atomizer, at 265 and 398 kW m, N decreased below the first-generation e-cig, whereas volume concentrations greatly increased, due to the formation of super micron droplets. Higher volume concentrations were observed for the 80/20 VG/PG liquid, because of VG vaporization and of its decomposition products, greater than for PG. For the double coil atomizer, increasing the electric power from 40 W (208 kW m) to 80 W (365 kW m) possibly led to a critical heat flow condition, causing a reduction of the number concentrations for the VG/PG 50/50 liquid, an increase for the 80/20 VG/PG liquid and a decrease of the volume concentrations for both of them. Coherently, the main mode was at about 0.1 µm on both metrics for both liquids. For the other tests, two main modes (1 and 2 µm) were observed in the volume size distributions, the latter becoming wider at 100 and 150 W (265 and 398 kW m), suggesting the increased emission of light condensable decomposition products. The lower aerosol emissions observed at 150 W than at 100 W suggest the formation of gas-phase decomposition products. The observation of low-count high-volume aerosols addresses the relevance of the volume metric upon measuring the second-hand concentration of the aerosols released by sub-ohm e-cigarettes.
Topics: Aerosols; Electronic Nicotine Delivery Systems; Humans; Nicotine; Propylene Glycol; Vaping
PubMed: 34770123
DOI: 10.3390/ijerph182111606 -
Nicotine & Tobacco Research : Official... Aug 2019Free radicals and carbonyls produced by electronic cigarettes (e-cigs) have the potential to inflict oxidative stress. Recently, Juul e-cigs have risen drastically in...
INTRODUCTION
Free radicals and carbonyls produced by electronic cigarettes (e-cigs) have the potential to inflict oxidative stress. Recently, Juul e-cigs have risen drastically in popularity; however, there is no data on nicotine and oxidant yields from this new e-cig design.
METHODS
Aerosol generated from four different Juul flavors was analyzed for carbonyls, nicotine, and free radicals. The e-liquids were analyzed for propylene glycol (PG) and glycerol (GLY) concentrations. To determine the effects of e-liquid on oxidant production, Juul pods were refilled with nicotine-free 30:70 or 60:40 PG:GLY with or without citral.
RESULTS
No significant differences were found in nicotine (164 ± 41 µg/puff), free radical (5.85 ± 1.20 pmol/puff), formaldehyde (0.20 ± 0.10 µg/puff), and acetone (0.20 ± 0.05 µg/puff) levels between flavors. The PG:GLY ratio in e-liquids was ~30:70 across all flavors with GLY being slightly higher in tobacco and mint flavors. In general, when Juul e-liquids were replaced with nicotine-free 60:40 PG:GLY, oxidant production increased up to 190% and, with addition of citral, increased even further.
CONCLUSIONS
Juul devices produce free radicals and carbonyls, albeit, at levels substantially lower than those observed in other e-cig products, an effect only partially because of a low PG:GLY ratio. Nicotine delivery by these devices was as high as or higher than the levels previously reported from cigarettes.
IMPLICATIONS
These findings suggest that oxidative stress and/or damage resulting from Juul use may be lower than that from cigarettes or other e-cig devices; however, the high nicotine levels are suggestive of a greater addiction potential.
Topics: Electronic Nicotine Delivery Systems; Flavoring Agents; Free Radicals; Humans; Nicotine; Oxidative Stress; Propylene Glycol
PubMed: 30346584
DOI: 10.1093/ntr/nty221 -
Heliyon Jun 2023This investigation dealt with the thermodynamic properties, saturated solubility values, and solvation behavior of deferiprone as an oral iron chelator agent in...
This investigation dealt with the thermodynamic properties, saturated solubility values, and solvation behavior of deferiprone as an oral iron chelator agent in non-aqueous mixtures of propylene glycol and 2-propanol using experimental measurements and mathematical correlations. The solubility of deferiprone demonstrated a positive correlation with both temperature and propylene glycol mass fraction. Four mathematical models were employed to correlate the solid-liquid equilibrium data, and the low mean relative deviation values of less than 3.6% illustrate the good agreement of computed data with the experimental data. The apparent thermodynamic behavior of deferiprone dissolution was also investigated according to van't Hoff and Gibbs equation.
PubMed: 37426787
DOI: 10.1016/j.heliyon.2023.e17402 -
Use of Propylene-Glycol as a Cosolvent for GnRH in Synchronization of Estrus and Ovulation in Sheep.Animals : An Open Access Journal From... May 2020The foreseen shortage of eCG for estrus synchronization in sheep makes necessary the development of alternative protocols. The aim of the present work was to evaluate...
The foreseen shortage of eCG for estrus synchronization in sheep makes necessary the development of alternative protocols. The aim of the present work was to evaluate the reproductive response of sheep in breeding season to the administration of GnRH using propylene-glycol as a cosolvent and the subcutaneous route for slowing and extending the release of GnRH, as well as the most adequate timing for such administration. In the present study, protocols based on a short-term CIDR treatment and a single subcutaneous dose of GnRH in propylene-glycol at 36 h after CIDR removal induced a similar ovarian response to protocols based on administration of eCG at CIDR removal or intramuscular GnRH in distilled water at 56 h after. In such protocol, 80% of the animals developed estrus in a narrow timing (75% between 36 and 48 h after CIDR removal), and all of them also ovulated in a narrow window (87.5% between 72 and 76 h after CIDR removal, with 62.5% between 72 and 76 h) and showed a similar ovulation rate and plasma progesterone concentrations at the induced estrous cycle. Hence, administration of GnRH in propylene-glycol may constitute an alternative to traditional protocols based on the administration of eCG.
PubMed: 32455785
DOI: 10.3390/ani10050897 -
Animals : An Open Access Journal From... Dec 2020Heat-stressed dairy animals increase their reliance on glucose. This elevated glucose demand is partially met by increasing the conversion of glucogenic amino acids (AA)...
Heat-stressed dairy animals increase their reliance on glucose. This elevated glucose demand is partially met by increasing the conversion of glucogenic amino acids (AA) in the liver. Propylene glycol (PG) is a glucogenic precursor and was not tested in dairy goats under thermoneutral (TN) and heat stress (HS) conditions simultaneously. We hypothesize that if HS-goats are fed with PG, they would get more glucose and consequently spare more glucogenic AA for milk protein synthesis rather than gluconeogenesis. Eight multiparous dairy goats (40.8 ± 1.1 kg body weight; 84 ± 1 days in milk) were used in a replicated 4 × 4 Latin square design of 4 periods; 21 d each (14 d adaptation, 5 d for measurements, and 2 d of transition). Goats were allocated to one of 4 treatments in a 2 × 2 factorial arrangement. Factors were control (CO) without PG or 5% of PG, and thermoneutral (TN; 15 to 20 °C) or heat stress (HS; 12 h/d at 37 °C and 12 h/d at 30 °C) conditions. Feed intake, rectal temperature, respiratory rate, milk yield, milk composition, and blood metabolites were measured. Compared to TN, HS goats had lower ( < 0.01) feed intake (-34%), fat-corrected milk (-15%), and milk fat (-15%). Heat-stressed goats also tended ( < 0.10) to produce milk with lower protein (-11%) and lactose (-4%) contents. Propylene glycol increased blood glucose (+7%; < 0.05), blood insulin (+37%; < 0.10), and body weight gain (+68%; < 0.05), but decreased feed intake (-9%; < 0.10) and milk fat content (-23%; < 0.01). Furthermore, blood non-esterified fatty acids (-49%) and β-hydroxybutyrate (-32%) decreased ( < 0.05) by PG. In conclusion, supplementation of heat-stressed dairy goats with propylene glycol caused milk fat depression syndrome, but reduced body weight loss that is typically observed under HS conditions. Supplementation with lower doses of PG would avoid the reduced feed intake and milk fat depression, but this should be tested.
PubMed: 33371268
DOI: 10.3390/ani10122449