Effects of supercritical CO2 extraction parameters on chemical composition and free radical-scavenging activity of pomegranate (Punica granatum L.) seed oil

Pomegranate (Punica granatum L.) seed oil (PSO) was prepared by supercritical CO₂ (SC-CO₂) extraction technology. Changes in the yield, chemical composition and free radical-scavenging activity of PSO under different extraction parameters were investigated. The results of SC-CO₂ extraction revealed that extraction pressure was the dominant factor to affect the oil yield. PSO was characterized by a high content of punicic acid (approximately 60%) and γ-tocopherol (more than 300 mg/100 g oil). A slight increase in the contents of punicic acid, arachidic acid and gadoleic acid was observed under higher extraction pressure and temperature. At lower pressure or shorter extraction time, PSO with high amount of total tocopherols was obtained. PSO extracted by SC-CO₂ showed strong free radical-scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenz-thiazoline-6-sulfonic) diammonium salt (ABTS) radicals and its scavenging ability was correlated with the level of tocopherols in extracted oils.     

Lipase Catalyzed Synthesis of Medium-chain Biodiesel from Cinnamonum camphora Seed Oil

The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid (53.4%) and lauric acid (38.7%). With immobilized lipase Candida sp. 99–125 as catalyst, several important factors for reaction conditions were examined through orthogonal experiments. The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5 (oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at 170 r·min^− 1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.     

Transesterification of waste cooking palm oil by MnZr with supported alumina as a potential heterogeneous catalyst

The transesterification of waste cooking palm oil (WCPO) with methanol into fatty acid methyl esters (FAMEs) was investigated using solid acidic mixed oxide catalysts Mn_3.5xZr_0.5yAl_xO₃ prepared via coprecipitation. The effects of reaction temperature, time, molar methanol-to-oil ratio, and catalyst loading were investigated. The stability of the catalytic activity was examined via leaching and reusability tests through five consecutive batch runs. The catalyst achieved a FAME content of more than 93%, and the optimal reaction conditions are as follows: reaction temperature of 150 °C, reaction time of 5 h, molar methanol-to-WCPO ratio of 14:1, and catalyst loading of 2.5 wt.%.     

Chloride-induced corrosion of steel in cracked concrete – Part I: Experimental studies under accelerated and natural marine environments

Parallel corrosion experiments were carried out for 2¼ years by exposing one half of 210 beam specimens (120 × 130 × 375 mm long) to accelerated laboratory corrosion (cyclic wetting and drying) while the other half underwent natural corrosion in a marine tidal zone. Experimental variables were crack width w_cr (0, incipient crack, 0.4, 0.7 mm), cover c (20, 40 mm), binder type (PC, PC/GGBS, PC/FA) and w/b ratio (0.40, 0.55). Results show that corrosion rate (i_corr) was affected by the experimental variables in the following manner: i_corr increased with increase in crack width, and decreased with increase in concrete quality and cover depth. The results also show that the corrosion performance of concretes in the field under natural corrosion cannot be inferred from its performance in the laboratory under accelerated corrosion. Other factors such as corrosion process should be taken into account.     

Lipase-catalyzed acidolysis of canola oil with caprylic acid to produce medium-, long- and medium-chain-type structured lipids

Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids (SLs) containing medium-chain fatty acid (M) at position sn-1,3 and long-chain fatty acid (L) at the sn-2 position in a solvent-free system. Six commercial lipases from different sources were screened for their ability to incorporate caprylic acid into the canola oil. The sn-1,3 regiospecificity toward the glycerol backbone of canola oil of the lipases with relatively higher acidolysis activity was compared by investigating the fatty acid profiles of the products. The results showed that Lipozyme RM IM from Rhizomucor miehei resulted in the highest caprylic acid incorporation ability and the lowest acyl migration. The reaction parameters including substrate mole ratio, enzyme load, reaction time and temperature of Lipozyme RM IM were investigated. Incorporation of caprylic acid was higher when reactions were carried with 10% lipase of the total weight of substrates with a 1:4 mole ratio of oil and caprylic acid. The optimal time course and temperature for synthesis SLs were 15 h and 50–60 °C. Possible triacylglycerol species and physical properties of the SLs product obtained at relative optimal conditions were characterized.     

Chloride-induced corrosion of steel in cracked concrete—Part II: Corrosion rate prediction models

Chloride-induced corrosion rate (i_corr) prediction models for RC structures in the marine tidal zone that incorporate the influence of crack width (w_cr), cover (c) and concrete quality are proposed. Parallel corrosion experiments were carried out for 2¼ years by exposing one half of 210 beam specimens (120 × 130 × 375 mm long) to accelerated laboratory corrosion (cyclic wetting and drying) while the other half underwent natural corrosion in the tidal zone. Experimental variables were w_cr (0, incipient crack, 0.4, 0.7 mm), c (20, 40 mm), binder type (PC, PC/GGBS, PC/FA) and w/b ratio (0.40, 0.55). The two proposed models (one each for accelerated and natural i_corr) can aid not only in quantifying the propagation phase, but also provide a novel way to select c, w_cr and concrete quality.     

Photo-responsive liposomes decorated with hydrophobically modified poly(vinyl alcohol)–coumarin conjugate

Photo-responsive liposome was developed by modifying the surface of egg yolk phosphatidylcholine (egg PC) liposomes with hydrophobically modified poly(vinyl alcohol)–epoxypropoxy coumarin conjugate (HmPVA-EPC). Decanoyl chloride (DC) was used as a hydrophobic pendant for the hydrophobic modification of PVA. The fluorescence quenching of liposomes was more than 65% when the ratio of lipid/HmPVA-EPC was 1:0.01–1:0.1, but the value was less than 35% in the ratio range of 1:0.2–1:1. Under UV irradiation (λ = 254 nm), egg PC liposomes of which lipid/HmPVA-EPC ratio was 1:0.1 readily release their content for 60 min possibly due to the photo-dimerization of EPC residues.     

Investigation of the carbonation mechanism of CH and C-S-H in terms of kinetics,microstructure changes and moisture properties

The purpose of this article is to investigate the carbonation mechanism of CH and C-S-H within type-I cement-based materials in terms of kinetics, microstructure changes and water released from hydrates during carbonation. Carbonation tests were performed under accelerated conditions (10% CO₂, 25 °C and 65 ± 5% RH). Carbonation profiles were assessed by destructive and non-destructive methods such as phenolphthalein spray test, thermogravimetric analysis, and mercury intrusion porosimetry (destructive), as well as gamma-ray attenuation (non-destructive). Carbonation penetration was carried out at different ages from 1 to 16 weeks of CO₂ exposure on cement pastes of 0.45 and 0.6 w/c, as well as on mortar specimens (w/c = 0.50 and s/c = 2). Combining experimental results allowed us to improve the understanding of C-S-H and CH carbonation mechanism. The variation of molar volume of C-S-H during carbonation was identified and a quantification of the amount of water released during CH and C-S-H carbonation was performed.     

Estimating hydrogen sulfide solubility in ionic liquids using a machine learning approach

For the design and development of new processes of gas sweetening using ionic liquids (ILs), as promising candidates for amine solutions, an amazing model to predict the solubility of acid gases is of great importance. In this direction, in the current study, the capability of artificial neural networks (ANNs) trained with back propagation (BP) and particle swarm optimization (PSO), to correlate the solubility of H₂S in 11different ILs have been investigated. Different structures of three-layer feed forward neural network using acentric factor (ω), critical temperature (T_c), critical pressure (P_c) of ILs accompanied by pressure (P) and temperature (T), as input parameters, were examined and an optimized architecture has been proposed as 5–9–1.Implementation of these models for 465 experimental data points collected from the literature shows coefficient of determination (R²) of 0.99218 and mean squared error (MSE) of 0.00025 from experimental values for PSO-ANN predicted solubilities while the values of R² = 0.95151 and MSE = 0.00335 were obtained for BP-ANN model. Therefore, through PSO training algorithm we are able to attain significantly better results than with BP training procedure based on the statistical criteria.     

Nanocrystalline scandia-doped zirconia (ScSZ) powders prepared by a glycine–nitrate solution combustion route

Nanocrystalline scandia doped zirconia (ScSZ) powders were synthesized by a solution combustion route using glycine, zirconyl nitrate and scandia as the starting materials. The properties of the as-synthesized powders are strongly influenced by the molar ratio of glycine-to-nitrate (g/n), where with the g/n ratio increasing from 0.14 to 1.12, the crystallite sizes of the powders decrease from 15.9 to 7.9 nm. 11ScSZ powders of specific surface areas up to 29 m²/g can be obtained through adjusting the initial g/n to 0.56 or greater. Incorporation of an appropriate amount of PEG dispersant into the starting solution can reduce the tendency of hard agglomeration formation. Investigations showed that powders from start solutions with the PEG incorporation have better sinterability than that of powders without the initial PEG incorporation, e.g., with the incorporation of 1.5 wt.% PEG dispersant in the starting solution, the resultant powders can be sintered to over 96% of theoretical density at 1200 °C, which is nearly 100 °C lower than that of powders without the initial PEG incorporation.     

Electron beam irradiation of polycarbonate reinforced acrylonitrile butadiene rubber

The effects of electron beam irradiation and polycarbonate (PC) concentration on the properties of acrylonitrile butadiene rubber (NBR) were investigated. The electron beam irradiation doses were from 25 to 150 kGy, whereas the PC contents were from 10 to 30 phr. It was found that the mechanical properties of NBR such as tensile strength (TS), hardness and tear strength (Ts) were remarkably improved by the incorporation of PC, while elongation at break (E_b) and thermal properties were decreased. However, the improvement in TS of NBR/PC blends was strongly dependant on PC content, in which maximum improvements need higher doses. On the other hand, the maximum value of Ts for all the blend ratios was at 25 kGy, whereas the hardness increases with increasing irradiation dose. Moreover, it was observed that the fuel resistance of NBR/PC was higher than NBR and decreases by increasing the content of PC.     

Hydrolysis of triacylglyceridesin the presence of tin(IV) catalysts

Tin(IV)-based compounds (mono-n-butyltin hydroxide oxide (a), di-n-butyl-oxo-stannane (b), di-n-butyl tin dilaurate (c) and tin oxide (d)) were used as catalysts in the hydrolysis of triacylglycerides (TGs). The effects of the nature and amount of the catalysts, the nature of the TGs, the temperature and reaction time were evaluated. Compared with the usual industrial processes, these systems showed excellent activities at mild temperatures and pressures, and low amounts of catalyst (ca. 0.3% w/w_oil). Fatty acid (FA) conversions of ca. 97% were obtained at 180 °C, 4 h at oil:water:catalyst a molar ratio of 1:24:0.01 and, using soybean oil.     

Enhanced ferroelectric properties of Ce-substituted BiFeO3 thin films on LaNiO3/Si substrates prepared by sol–gel process

The effects of Ce substitution on the structural and electrical properties of multiferroic BiFeO₃ thin films grown on LaNiO₃/Si(1 0 0) substrates by a sol–gel process have been reported. X-ray diffraction data confirmed the substitutions of Ce into the Bi site with the elimination of all secondary phases under a substitution ratio x = 15%. The dielectric constants of the films increased from 90 to ～260 below 100 kHz with 5% molar Ce substitution and the films showed enhanced dielectric behavior. We observed a substantial increase in the remnant polarization (P_r) with Ce substitution and obtained a maximum value of ～71 μC/cm² by 5% molar Ce incorporation. The leakage current behavior at room temperature of the films was studied and it was found that the leakage current density decreased from 10^?6 to 10^?8 A/cm² for 5% molar Ce-substituted films under a field 150 kV/cm. The reduction of dc leakage current of Ce-substituted films is explained on the basis of relative phase stability and improved microstructure of the material.     

Synthesis and characterization of Ce–La oxides for the formation of dimethyl carbonate by transesterification of propylene carbonate

A series of cerium–lanthanum catalysts prepared using the co-precipitation method were investigated for transesterification of propylene carbonate (PC) with methanol to produce dimethyl carbonate (DMC). Synthesized catalysts were characterized by XRD, CO₂- and NH₃-TPD, N₂ adsorption/desorption and SEM–EDX techniques. Studies were carried out to study the effect of reaction conditions such as methanol/PC molar ratio (4–12), catalyst dose (2–10 wt.% of PC), reaction time (2–10 h) and temperature (140–180 °C) on the DMC yield. Highest PC conversion and DMC yield of 72% and 74%, respectively, were observed with catalysts having a 1:4 Ce/La molar ratio.     

High glass transition temperature bio-based copolyesters from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and isosorbide

New renewable copolymers were prepared from reactive bis-hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers (PHBHV-diol), isosorbide and 1,4-phenylene diisocyanate. First, microwave (MW)-assisted alcoholysis in the presence of ethylene glycol provides a rapid and straightforward method for engineering PHBHV-diol, with molar masses ranging from 700 to 4100 g mol^?1. These well-defined oligoesters were further used for the preparation of random copolymers of PHBHV-diol and isosorbide bridged with 1,4-phenylene diisocyanate via urethanization. The molar masses (M_n) of most copolyesters are about 10,000 g mol^?1 with polydispersities (DPI) in the range of 1.2–1.9. The dependence of the solid-state structures on the length of PHBHV block was carefully investigated. The incorporation of isosorbide units into the PHBHV backbone increased the glass-transition temperatures from +5 °C up to +34 °C.     

Synthesis and self-assembly of biomimetic phosphorylcholine-bound chitosan derivatives

Biomimetic N-phosphorylcholine (PC)-chitosan derivatives (PCCs) with a phosphoramide linkage between glucosamine and PC in various degree of substitution (DS) were synthesized through Atherton–Todd reaction and subsequently hydrolysis under the mild conditions, and structurally characterized by ¹H NMR, ³¹P NMR, FT-IR and GPC. The incorporation of zwitterionic PC groups modified the hydrophilic/hydrophobic balance of chitosan derivatives to induce the formation of nanosized micelles by self-assembly in neutral aqueous solution. Fluorescence measurements revealed that the critical aggregation concentration (CAC) of PCCs solutions increased with increasing the DS of PC. The physicochemical properties of PCCs aggregates in neutral aqueous solutions were investigated by AFM and dynamic light scattering (DLS). The results confirmed that the amphiphilic PCCs copolymers can self-assemble to form nanosized spherical micelles with zeta potential between 0 and 4 mV, suggesting that the PCCs nano-aggregates were mostly covered with electrically neutral zwitterionic PC groups. Furthermore, all the PCCs samples showed low toxicity against NIH/3T3 cells after incubated for 4 h or 24 h, indicating their safety for biomedical application.     

n-Butyl acrylate production by esterification of acrylic acid with n-butanol combined with pervaporation

In this study, the esterification reaction of acrylic acid and n-butanol to produce n-butyl acrylate and water was studied using the pervaporation–esterification hybrid process to perform the separation and reaction simultaneously to increase the conversion of limiting reactant. A Pervap 2201 polymeric membrane was used to separate water and also to shift the equilibrium. The Pervap 2201 membrane showed high selectivity to water in the n-butanol, acrylic acid, n-butyl acrylate, and water reaction system. The effects of temperature, the initial molar ratio of n-butanol to acrylic acid, catalyst loading, and the ratio of membrane area to reaction volume (S/V) were studied. The maximum conversion of acrylic acid was calculated as 96.3% at a temperature of 358 K, a molar ratio of 8, with a catalyst loading of 10 g/L and an S/V ratio of 70 m⁻¹.     

Structured phosphatidylcholine with elevated content of conjugated linoleic acid: Optimization by response surface methodology

Structured phosphatidylcholine was successfully produced by immobilized phospholipase A₁ catalyzed acidolysis of phosphatidylcholine and CLA. Response surface methodology was applied to optimize the reaction system using three process parameters: enzyme load, temperature, and substrates molar ratio. Optimal conditions obtained from the model were 15% enzyme load at 55°C for a 1:4 (PC/CLA) substrates molar ratio, which produced a yield of 85.8% of CLA incorporation. The total correlation coefficient (R²) was 0.92 and no lack of fit was detected. This suggests the fitness of the model obtained and it suggests that the model is sufficiently accurate to estimate the incorporation of CLA into PC. Practical applications: This study could contribute to process development for enzyme catalyzed phospholipid modification. By changing the fatty acid composition of lecithin, delivery of desired (beneficial) fatty acids could be better achieved. Additionally, emulsification properties of the phospholipids could open a wide area of applications in the food and cosmetic industries.     

Biodiesel production from waste cooking oil in a microtube reactor

Waste cooking oil (WCO) was used to produce biodiesel in a microtube reactor. First, the acid value of the WCO was reduced from 3.96 mg KOH/g to less than 1 mg KOH/g via acid catalyzed esterification. The effects of the methanol-to-WCO molar ratio (4.5:1–18:1), the H₂SO₄ concentration (0.5–2 wt.%), reaction temperature (55–70 °C), and reaction time (5–20 s) were studied. The optimal conditions were 9:1 methanol-to-WCO molar ratio, 1 wt.% H₂SO₄, 65 °C and 5 s of reaction time. Triglycerides in the product from the first step were transesterified with methanol and alkaline catalyst. Methyl ester content of the biodiesel was 91.76%.     

Crack profiles under a Vickers indent in silicon nitride ceramics with various microstructures

The effect of microstructure on crack morphology under a Vickers indentation was studied using 20 various silicon nitride ceramics including bearing-grade silicon nitrides. The indentation load was decreased from 98 N to 9.8 N and a transition of the crack types from half-penny crack to radial one was observed with both decoration method and serial sectioning technique. All of the indented samples possessed the half-penny cracks at the load of 98 N. The transition of crack profiles in the samples with coarse microstructure occurred when the load decreased from 49 N to 19.6 N, whereas the transition load for the sample with fine microstructure was ～9.8 N. Half-penny cracks were formed regardless of the microstructures when the ratio of the half of crack length to the half of diagonal size of an indentation, c/a, was above ～2. The dependence of the transition load on both Vickers hardness and fracture resistances was analyzed using Pajares's equation.