Acetone Research Articles

Volatile compounds for biotechnological applications produced during competitive interactions between yeasts and fungi.

Fungi, yeasts and bacteria produce volatile compounds during their metabolism. In this study, the volatile compounds produced by yeast strains (Saccharomyces cerevisiae and Rhodotorula mucilaginosa) and fungal strains (Aspergillus carbonarius and Aspergillus ochraceus) during competitive interactions were investigated by solid-phase microextraction coupled with gas chromatography-mass spectrometry. Fifty-six volatile compounds were identified representing alcohols, aldehydes, esters, ketones, aromatic compounds, acids, furans, phenols, and nitrogen compounds, being the largest amount in the class of esters and alcohols. Eight compounds were identified only in interactive culture conditions such as 2-amino-1-propanol, isopropylamine, dimethylamine, pentyl propanoate, ethyl-2-aminopropanoate, acetone, oxalic acid, and β-elemene and five of these were produced in cocultures including A. carbonarius. These will be developed for future biotechnological applications such as in the pharmaceutical and biological industry to produce drugs. Antimicrobial and antifungal activities; Solvent and herbicide; flavoring ingredient; solvent, plastic synthesis, nail polish remover and thinner, pesticide and herbicide; important in the complexation of minerals in the soil; and plant-environment interactions, defending predators, pathogens, and competitors.

Low-Temperature Phase Equilibria in an Ethylene Glycol–Acetone System

An ethylene glycol (EG)–acetone (AC) system is studied via differential scanning calorimetry in the −140 to +40°С range of temperatures. A phase diagram is plotted over the range of concentrations. It is found that the mixtures in the system are supercooled by more than 30°C. Low-temperature melting is recorded in the region around −98°C, which corresponds to the eutectic point temperature. The devitrification of rapidly cooled samples is observed in the range of concentrations up to ~21 mol % AC, and the temperature of devitrification is determined (Tg ~ −120°C). The plotted phase diagram of the EG–AC system is compared to a water–acetone phase diagram.

Utilization of smartphones for the evaluation of Gr/Ni nanostructures magnetically controlled based on optical fibers surface plasmons.

In the suggested optical fiber-based magnetoplasmonic system, we investigated the magnetic properties of graphene/nickel nanostructures. The plasmonic mode changes under the magnetic field observed in the intensity diagrams over time. To be accessible, cheap, and portable, we used a smartphone as a detector and processor. Considering the ambient noise and the light source, it was reported that the intensity of the changes improved up to 5 times. Further, the clad corrosion experiment carried out by pure dimethyl ketone in an intensity modulation by a smartphone camera and 10 seconds suggested removing fluorine polymer clad.

Aluminium-catalysed synthesis of aryl enol ethers from phenols and dimethyl ketals.

We report an environmentally friendly, aluminium-catalysed, halide- and transition metal-free method for the synthesis of aryl enol ethers from phenols and dimethyl ketals that involves ketal exchange driven by the removal of methanol. The obtained aryl enol ethers were transformed into the corresponding diaryl ethers by Pd/C-catalysed dehydrogenation or DDQ oxidation.

Synergistic Catalytic Oxidation of Typical Volatile Organic Compound Mixtures on Mn-Based Catalysts: Significant Promotion Effect and Reaction Mechanism.

The miscellaneous volatile organic compounds (VOCs) in industrial flue gas streams usually demonstrate significant mutual inhibition effects, and the behavior of a particular VOC in mixtures is not clear, which hinders the application of catalytic technology. This study examines the catalytic oxidation and mixing effects of representative VOCs in industrial exhausts, consisting of acetone (AC), ethyl acetate (EA), and toluene (Tol), on common Mn-based catalysts (e.g., MnO2, Mn2O3, LaMnO3, and Mn3O4) by means of intrinsic activity evaluation, coadsorption, VOC temperature-programmed oxidation, in situ diffuse reflectance infrared Fourier transform spectroscopy, and gas chromatography-mass spectrometry. The results showed no inhibiting effect on the conversion of these VOCs when combusted together; instead, a significant mutual promotion effect was found, especially on Tol destruction, with a sharp decrease in the Tol T50 from 214 to 158 °C on MnO2. It is proposed for the first time that the addition of AC/EA in Tol combustion leads to the generation of o/m-methyl phenol, which changes the rate-determining step of the ring-opening process, thus elevating the conversion of Tol together with AC and EA in the mixture at low temperatures.

Characteristics, sources and health risk assessment of atmospheric carbonyls during multiple ozone pollution episodes in urban Beijing: Insights into control strategies

Carbonyls have attracted continuous attention due to their critical roles in atmospheric chemistry and their potential hazards to the ecological environment and human health. In this study, atmospheric carbonyls were measured during several ground-level-ozone (O3) pollution episodes at three urban sites (CRAES, IEP and BJUT) in Beijing in 2019 and 2020. Comparative analysis revealed that the carbonyl concentrations were 20.25 ± 6.91 ppb and 13.43 ± 5.13 ppb in 2019 and 2020 in Beijing, respectively, with a significant spatial trend from north to south, and carbonyl levels in urban Beijing were in an upper-intermediate range in China, and higher than those in other countries reported in the literature. A particularly noteworthy phenomenon is the consistency of carbonyl concentrations with variations in O3 concentrations. On O3 polluted days, the carbonyl concentrations were 1.3–1.5 times higher than those on non-O3 polluted days. Secondary formation contributed more to formaldehyde (FA) and acetaldehyde (AA) on O3 polluted days, while the anthropogenic emissions were more significant for acetone (AC) on non-O3 polluted days. Vehicle exhaust and solvent utilization were the main primary contributors to carbonyls. Due to reduced anthropogenic emissions caused by the COVID-19 lockdown and the “Program for Controlling Volatile Organic Compounds in 2020” in China, the contributions of primary emissions to carbonyls decreased in 2020 in Beijing. Human cancer risks to exposed populations from FA and AA increased with elevated O3 levels, and the risks still remained on non-O3 polluted days. The residents around the BJUT site might experience relatively higher human cancer risks than those around the other two sites. The findings in this study confirmed that atmospheric carbonyl pollution and its potential human health hazards cannot be ignored in urban Beijing; therefore, more strict control strategies for atmospheric carbonyls are urgently needed to better protect human health in Beijing in the future.

Regulating monolayer WO4 tetrahedral units to promote a sustainable 4,4-Bisphenol-A industrial process

Catalysts for 4,4-Bisphenol-A (BPA) production have moved from mineral acid (HCl) to bi-functional (-SO3H and -SH) resins, with high performance but limited lifespan while non-regenerable. How to achieve regenerable acidic catalysts with comparable performance as resin catalysts remains a challenge. Here, using a facile and rational approach, we present that the Indium and Titanium dual-doped W-based catalysts give full acetone (ACT) conversion within 2 h at > 96% 4,4-BPA selectivity, being higher than those over commercial resin catalysts. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) analysis reveal that the well-organized monolayer WO4 tetrahedral units promoted by In and Ti act as the active species, being highly stable up to 800 °C and regenerable via simple calcination. The performance has been validated via life test (> 8000 h) using crude phenol feedstock. This advance will give strong impacts on sustainable industrial processes beyond 4,4-BPA production, with great potential extending to other acid catalyzed reactions.

Experimental Study of the Reduction in Ceramide Content in Fingernails Due to Nail Polish Remover Use

The amount and distribution of ceramide, an intercellular lipid, in the fingernails of three Japanese women in their twenties were examined by high-performance liquid chromatography and antibody staining. In addition, the structural changes of fingernail cross sections were examined after fingernails were immersed in an acetone-based nail polish remover solution. The acetone-treated fingernails had a lower water content and higher water evaporation than the inner forearm skin and healthy fingernails, suggesting that they had compromised moisturizing and barrier functions and were more susceptible to roughness and damage. These results also suggest that, compared to healthy fingernails, rough fingernails are more prone to breakage and damage. Furthermore, it was found that the amount of ceramide decreased when fingernails were immersed in nail polish remover solution. The distribution showed ceramide to be present in the ventral and dorsal regions of the free edge of the fingernail plate. After immersion in nail polish remover, the three-layered structure of the free edge of the plate was intact, but the dorsal distal edge of the plate peeled off. Gaps were observed inside the free edge of the plate, which should have been layered. These results show that the frequent use of nail polish remover may worsen condition of fingernails.

Contribution of the Solvent Extraction Method for Phenolic Compounds, Flavonoids, and Fucoxanthin to the Antioxidative Properties in Extracts of Chaetoceros tenuissimus Meunier

Chaetoceros sp. has been found to possess significant amounts of valuable fucoxanthin, phenolics, and flavonoids, with enormous nutraceutical and antioxidant potential. The aim of this study was to employ ultrasound-assisted extraction to determine the antioxidant properties of extracts prepared from Chaetoceros tenuissimus using different solvents: Propylene glycol (PG), acetone (AC), and methanol (ME), with difference ultrasonication times (15 and 30 min). The total phenolic (TPC), flavonoid (TFC), and fucoxanthin (FUC) contents were evaluated. Antioxidant capacity was evaluated by DPPH and ABTS radical-scavenging assays and lipid peroxidation by TBARS. The FUC content was analyzed by HPLC-DAD. 30-min PG extract (PG-30) exhibited the highest TPC (2.75 ± 0.14 mg GAE.g−1 DW), and FUC (8.76 ± 0.06 mg FUC. g−1). Concerning total antioxidant capacity, PG-30 was the most effective against DPPH• (IC50 = 970.19 ± 7.70 µg. mL−1) and TBARS (IC50 = 717.05 ± 1.45 µg. mL−1), while 15-min PG extract (PG-15) presented the highest inhibitory activity against ABTS+• (IC50 = 150.02 ± 6.95 µg. mL−1). The study findings demonstrate that PG extracts of C. tenuissimus exhibit high potential antioxidant activity, likely associated with their content of FUC and phenolics, and could be used in cosmetic preparations and as phytonutrients. HIGHLIGHTS Chaetoceros tenuissimus Meunier from Chonburi province, Thailand High antioxidant activities of tenuissimus extracts by ultrasound assisted extraction with different solvents The correlation between chemical substances content and antioxidant activity GRAPHICAL ABSTRACT

Sensing properties of acetone gas on the two-dimensional orthorhombic diboron dinitride sheet: A DFT investigation

In recent years, the removal of various organic solvents from different mediums, particularly through nano-structured materials, has an important place in various industries, for example in producing novel versatile nano-adsorbents. Within this work, dispersion-corrected DFT is employed for investigating how the acetone (ACT) molecule is adsorbed on the o-B2N2 monolayer (o-B2N2ML) because computational methods have been considered as powerful tools to explore molecular systems at the atomic level and to explore the nature of interactions. Here, by investigating charge transports, density of states, electronic/energy properties, and orbitals, the experimental observations are inspected at the molecular level. A relationship is established between the sensor response (R) and its Eg (the energy gap between the HOMO and the LUMO). ACT interacts strongly with the o-B2N2ML with the energy of adsorption of −17.82 kcal/mol. The adsorption of ACT on o-B2N2ML is a strong physical adsorption. After ACT is adsorbed, there is an increase in the conductivity of these systems, which makes the application of o-B2N2ML as an electrical gas sensor possible. The sensor recovery time is 428 s, which is similar to the experimental value.

Exhaust emission reduction of a SI engine using acetone–gasoline fuel blends: Modeling, prediction, and whale optimization algorithm

Acetone–gasoline fuel is one potential favorable alternative option to regular gasoline fuel. This work attempts to mitigate pollution while simultaneously improving SI engine performance with acetone (AC) proportion in fuel mixture and varying engine speed. Acetone–gasoline alternative fuel was experimentally prepared by mixing 5–10 vol.% of acetone into ordinary gasoline. The experiments were performed in a spark ignition (SI) single-cylinder, four-stroke at variable engine speed. The engine performance was measured by an eddy current dynamometer (ECD), while the exhaust engine was measured by a gas analyzer connected to the gasoline engine. The proposed strategy, the integrated combined polynomial regression with whale optimization algorithm (WOA), was implemented. The results showed that the acetone blending of 10 % with gasoline (AC10: 10 vol. % acetone + 90 vol. % gasoline) decreases carbon monoxide (CO), unburned hydrocarbon (UHC), and nitrogen oxides (NOx), emissions by 26.3%, 30.3%, and 6.6%, respectively. Furthermore, the AC10 exhibited better engine brake power (BP) than pure gasoline, with an improvement of 4.39%. According to the optimization results, the BP was enhanced by AC10 to record 2.426 kW at 2887 rpm. In addition, engine emissions reduced to the lowest levels of 142.849 ppm, 0.426%, and 1088.178 ppm, in terms of UHC, CO, and NOx, respectively. The experiment results show that the WOA optimizer can accurately predict the optimal point in SI engine performance and emissions.

Cleaning and microstructural effects of amyl acetate on pulp chamber dentin impregnated with epoxy resin-based endodontic sealer.

To evaluate the cleaning potential of 95% ethanol, acetone, and amyl acetate solutions used solely or in association, to remove epoxy resin-based sealer residues from pulp chamber dentin and their microstructural effects. One hundred and eighty bovine incisor specimens were divided into nine groups according to the cleaning protocol: ET (ethanol); AC (acetone); AA (amyl acetate); E1: AA+AC; E2: AA+ET; E3: AC+ET; E4: AA+AC+ET; PC (positive control), and NC (negative control). All groups were impregnated with epoxy resin-sealer, except NC. Ninety specimens were divided into groups (n=10) for evaluation of persistence of residues and amount of open dentinal tubules by SEM analysis and evaluation of chemical compounds on the dentin surface after cleaning with electron dispersive spectroscopy. The others 90 specimens were submitted to Knoop microhardness evaluation. Persistence of residues data were submitted to the Kruskal Wallis and Dunn tests (α=0.05). Open dentinal tubules and microhardness data were submitted to one-way ANOVA and Mann Whitney tests (α=0.05). AA and E4 protocols showed the lowest persistence of residues. E4 group had the highest incidence of open dentinal tubules. E3 and E4 groups showed no changes in the atomic ratio Ca/P, which was similar to NC group. E4 group did not present W, an element presents in all the other groups. ET and E4 protocols showed the smallest reduction in dentin microhardness. The combination of amyl acetate, acetone and ethanol is the most effective and safe protocol to remove epoxy sealer residues on pulp chamber dentin. Moreover, it has the lowest microhardness reduction. The combined use of amyl acetate, acetone, and ethanol enhanced the cleaning of pulp chamber dentin with minimal microstructural damage.

First-principles kinetic Monte Carlo modeling of propylene epoxidation on the Ti2CuO6/Cu(111) and Cu2O(111) surfaces

Direct propylene epoxidation by molecular oxygen is one of the most important commercial selective oxidation reactions. Although the mixed metal oxide (Ti2CuO6/Cu(111)) with highly dispersed and stabilized Cu+ has high selectivity toward propylene oxide (PO), the reaction mechanism and the physical nature of stable Cu+ involved in Ti2CuO6/Cu(111) remain unclear. To better understand the key role of stabilized Cu+ active sites, the systematic kinetic Monte Carlo (kMC) studies of the propylene epoxidation reaction on Ti2CuO6/Cu(111) and Cu2O(111) surfaces are carried out. It was found that O2 is weakly bound to Ti2CuO6/Cu(111) due to the less active of Cu+ ions compared to that of Cu+ ions in Cu2O(111), which can exist stably. The current simulation demonstrates that the relatively stable Ti2CuO6/Cu(111) mixed oxide exhibits better PO selectivity and activity than Cu2O(111). The reasons for the different catalytic performance are revealed: For the primary chemistry of propylene epoxidation mechanism, Cu2O(111) favors the first allylic hydrogen stripping, while Ti2CuO6/Cu(111) has an excellent open-shell electronic structure character, which makes it more reactive toward the propylene double bond to form the oxametallacycle (OOMMP or OMMP). For the secondary chemistry of propylene epoxidation mechanism, the energy barrier of PO formation is smaller than that of propanal(PA)/acetone(AC) due to the larger difference in bonding affinity toward the O and C atoms. In contrast, the opposite trend holds for Cu2O(111). In addition, the surface species can be balanced quickly on Ti2CuO6/Cu(111). The catalyst surface is not poisoned because the surface species coverage is moderate, which means that Ti2CuO6/Cu(111) remains highly stable during the reaction processes. The Cu2O(111) has fewer active sites due to higher surface species coverage (i.e., catalyst poisoning). One may rationally design an efficient propylene epoxidation catalyst based on the present work, i.e., doping Cu into the stable spinels or perovskites such as Cu-modified LaCoO3 perovskites (LaCoxCu1−xO3−δ) may show the similar catalytic properties like that of Ti2CuO6/Cu(111).

Ethyl acetate from nail polish remover inhalation in a case of fatal voluntary intoxication

To describe a case of fatal voluntary intoxication involving ethyl acetate (EA) inhalation. A 57-year-old woman was found dead on her bed with a plastic bag over her head filled with cotton balls soaked with nail polish remover. Several empty nail polish remover bottles corresponding to a total volume of approximatly one liter of EA, were found near the body. Among her medical history, gastric banding, an orphan disease that required numerous orthopedic surgeries, depression and suicide attempts were notified. Medications were found at home such as venlafaxine, lorazepam, acetaminophen and zopiclone. At the autopsy, no traumatic injuries were observed. A non-specific asphyxia syndrome with organ congestion was notified with macroscopic lesions in favor of an acute or subacute pathological condition with obstruction of the upper airways by gastric contents up to the main bronchi resulting in pulmonary edema. Anoxia was confirmed by the findings of the microscopic examination. The following samples were available for toxicological analysis: peripheral and cardiac blood, urine, stomach content and bile. A comprehensive forensic toxicological expertise was carried out including investigation of illegal drugs, prescribed drugs, alcohol, volatile substances and other poisons like carbon monoxide with several screenings (immunoassay, gas chromatography-mass spectrometry and liquid chromatography-mass tandem) of various postmortem samples. Each substance detected was quantified by a validated method. Lorazepam, zopiclone and venlafaxine and metabolite were quantified by high-performance liquid chromatography with photodiode-array detection. EA, ethanol and methanol were quantified by gas chromatography and static headspace gas chromatography with flame ionization detector. Peripheral blood concentrations of lorazepam, zopiclone and venlafaxine and O-desmethyl-Venlafaxine were respectively at 55, 49, 414 and < 20 μg/L. EA and ethanol concentrations were at 0.033 and 2.58 g/L in peripheral blood, at 0.034 and 2.76 g/L in cardiac blood, at 0.069 and 2.33 g/L in urine, at 0.155 and 2.27 g/L in stomach content and at 0.014 and 2.87 g/L in bile. EA is commonly used as component in nail polish remover. After exposure to EA vapor, absorption is mainly respiratory and percutaneous. Distribution involves all organs but predominates in fatty tissues. EA is rapidly metabolized by plasma esterases resulting in ethanol and acetic acid synthesis. EA may cause drowsiness, sleepiness, unconsciousness, narcosis, stupor and central nervous system depression. These symptoms are potentiated with ethanol. In this case, the low ratio of EA to ethanol concentrations in all postmortem samples confirmed this rapid biotransformation. This was already mentioned in a case of accidental workplace exposure (Coopman. Forensic Sci Int 2005;154:92–95). Blood concentrations of prescribed drugs were here within the therapeutic range. An EA blood concentration of 0.033 g/L can therefore be considered lethal associated with an ethanol concentration around 2.6 g/L. To our knowledge, this is the first fatal case of voluntary intoxication with EA inhalation. The measured concentrations in all usual autopsy samples can be added to toxicological databases.

A shock tube experiment and an improved high-temperature diisopropyl ketone model by Bayesian optimization

Ignition delay times (IDTs) for di-isopropyl ketone (DIPK) were measured at pressures of 6 and 10 atm, equivalence ratios (ϕ) of 0.5, 1.0, and 2, and over a temperature range of 1100 - 1500 K. In the DIPK sub-model proposed by Barari et al., DIPK⇔IC3H7+IC3H7CO (R2) was erroneously written as DIPK⇔IC3H7+ IC4H7O and the consumption paths of dimethyl ketene (DMK) are missing. A DIPK sub-model was proposed on the basis of Barari model by correcting these errors, reassigning the rate coefficients of the DIPK unimolecular decomposition reactions (R1, R2), H-abstraction reactions by O˙H (R3, R4), fuel radical isomerization reaction (R5), and β-scission decomposition reactions (R5-R10) using the analogy method, and adopting the theoretical calculations of the H-abstraction reactions by H˙, C˙H3, and HO˙2 (R11-R16) provided by Allen et al.. The rate coefficients of R1-R10 were globally optimized by the Bayesian optimization algorithm using the experimental IDTs and profiles of DIPK and DMK. The optimized model well predicts not only the IDTs and profiles of DIPK and DMK, but also the laminar flame speeds and the profiles of many intermediates (propyne, propylene, and methyl ketene) and small species (H2, CO, CH4) during the pyrolysis of DIPK. The calculation using the method of Chen et al. shows that no optimized reaction violates the collision limit. The sensitivity and rate of production analysis were used to discuss the DIPK unimolecular decompositions, DIPK H-abstraction reactions, DIPK radicals isomerization and β-scission reactions, and the optimization of the DIPK sub-model.

Study on Hansen solubility parameters of nanodiamonds and its predictive role on dispersion states in polyethylene oxide casting with different solvent media

As one of the carbon-based nanomaterials with extremely superior and comprehensive performance, nanodiamonds (NDs) have very important research value and quite widespread commercial application prospects. The dispersion of NDs in different media greatly affects its actual performance. In this work, the dispersion state of NDs in 21 different kinds of solvents was investigated by observation method, dynamic light scattering (DLS) and ultraviolet-visible (UV–vis) light absorbance. The result showed that NDs are well dispersed in solvents with high polar component and appropriate hydrogen bond component parameters, such as dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF). Based on the dispersion tests, the Hansen solubility parameters (HSPs) of NDs were fitted by the Hansen sphere method using MATLAB software with results of δD = 17.5 MPa1/2, δP = 14.2 MPa1/2, δH = 10.5 MPa1/2, δt = 24.9 MPa1/2 and R0 = 9.5 MPa1/2. Three various kinds of solvents with different Hansen spatial distances (Ra) from the NDs, xylenes, acetone (ACE), and DMF, were further used to prepare polyethylene oxide (PEO) composites with 0.5 wt% NDs by casting, respectively. The composite prepared in the DMF with the smallest value of Ra among all the three, had a better dispersion of the fillers. The obtained HSPs of NDs enrich the database of HSPs of nanomaterials, which can not only guide us to choose suitable dispersion media of NDs, but also help us to evaluate the properties of NDs composites.

Synthesis and determination of pKa values of some new di-{2-ethoxy-6-[(3-substitue-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)azomethine]phenyl} terephthalates

In this study, seven novel di-{2-ethoxy-6-[(3-substitue-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)azomethine]phenyl} terephtalates (4a-g) were synthesized from the rections of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2a-g) with di-(2-formyl-6-ethoxyphenyl) terephtalate (3). The compounds 4a-g were characterized using by IR, 1H-NMR, 13C-NMR and UV spectral data. In addition, 4 type compounds were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as isopropanol, tert-butanol, dimethyl ketone, N,N-dimethylformamide and the half-neutralization potential values and the corresponding pKa values were determined for all cases.

Quantitative Phytochemical Screening and In-vitro Antioxidant Activities of Jatropha gossypifolia L. Leaf Extracts Aiming Antimicrobial and Therapeutical Applications

Total phenolic (polyphenols, flavonoids, and condensed tannins) contents and antioxidant property (DPPH, ABTS, FRAP) were evaluated in hexane (HE), acetone (AC), ethanol (ET), 70% (v/v) ethanol/water (EW), and powder extracts of Jatropha gossypifolia leaves using spectrophotometric methods. The lowest and highest contents of polyphenols (10.27 ± 0.36 and 21.23 ± 0.95 mg GAE/g), flavonoids (4.83 ±0.42 and 12.53 ±0.58 mg QE/g), and condensed tannins (3.03 ± 0.18 and 7.13 ± 0.12 mg CE/g) were recorded in powder and EW, respectively. EW exhibited the highest scavenging activities displayed by the lowest IC50 values (0.23±0.01 mg/mL DPPH and 0.2±0.03 mg/mL ABTS). Moreover, it recorded the highest reducing power (92.85±1.25 mg AAE/g), followed by HE (72.73±1.99 mg AAE/g) and AC (41.84±0.47 mg AAE/g). Relevant correlations were found between the polyphenols, flavonoids, condensed tannins and reducing antioxidant power (r = 0.986, p &lt; 0.01; r = 0.958, p &lt; 0.01; r =0.950, p &lt; 0.05; respectively). Based on their phytochemical and antioxidant properties, PCA classified the five extracts into three distinct clusters. The results of this study indicate that EW contains powerful bioactive molecules with noteworthy antiradical and electron donating properties. Therefore, it may be a promising candidate in the search for natural compounds with therapeutic and food/crop preservative applications.

Intermolecular interactions in binary mixtures of formamide and acetone

Trajectories from molecular dynamics simulations of binary mixtures of formamide (FA) and acetone (AT) have been analyzed across the entire concentration range by means of various pair distributions and topological network analysis techniques to probe the structure of the intermolecular interaction networks existing in these mixtures. Radial pair distributions clearly indicated H-bonding interactions between the two molecule types through acetone oxygen and the cis- and/or trans-hydrogens of formamide. Decomposition of pair energy distributions into possible intermolecular interaction types revealed that the most stable formamide-acetone dimers existing in the binary mixtures interact via an H-bonding. Orientational pair distributions have shown that both the AT-AT and the FA-FA pairs tend to adopt an antiparallel dipole orientation, as their respective pair interaction energies get smaller. And, the FA-AT pairs interacting stronger than −6.3 kcal/mol are found to adopt an orientation such that the angle between the dipole of AT and the C-N bond of FA is larger than 130°. Network neighborhood analysis evidently revealed that the formamides do not show a strong preference for either molecule types. As acetone mole fraction of the mixture is increased, the added ATs are found to be capable of substituting the formamides, to a great extent, in the region spanning their second-order neighborhood. Conversely, as formamide content of the mixture is increased, the added FAs fail to adequately substitute the ATs in the region spanning their second-order neighborhood. Guided by our molecular dynamics based observations regarding the different types of intermolecular interactions existing between formamide and acetone, five FA-AT dimeric structures are highlighted. Their interaction energies are computed with density functional theory at the mPW2PLYP/def2-TZVP level. The most stable dimer is found to have an interaction energy of −7.5 kcal/mol, to involve an O⋯HC hydrogen-bonding, and to have nearly coplanar formamide and acetone. In addition, the DFT structures and interaction energies of trimers of the form AT⋯FA⋯AT and FA⋯AT⋯FA are also reported.

Investigation of the oxygen coverage of propylene epoxidation on Ag(1 1 1) surfaces from DFT

The direct epoxidation of propylene on Ag(111) under different oxygen coverage conditions was systemically studied on the basis of density functional theory calculation and the general trends of oxygen coverage on the two parallel competitive reaction paths in propylene oxide (PO) formation: α-H stripping versus epoxidation and the generation of PO versus acetone (AC) were explored. Then, the PO formation selectivity was investigated. Results showed that increase in oxygen coverage enhanced the adsorption strength of adsorbed species, except the O* species. In the primary reaction of propylene epoxidation, high oxygen coverage facilitates the first α-H stripping process, and opposite trend was observed in epoxidation process. As for the secondary chemistry in propylene epoxidation, increase in oxygen coverage benefits PO and AC formation. The coverage of O* has considerable influences on the primary reaction but small influence on the secondary reaction. Although a high oxygen coverage benefits the first α-H stripping, the second α-H stripping has higher barrier than that in secondary chemistry, and thus the PO formation would be better than that of acrolein formation at higher oxygen coverage.