Oleic Acid Molecules Research Articles

Enhancing exciton-to-Mn2+ energy transfer and emission efficiency in Mn2+-doped CsPbCl3 perovskite nanocrystals via CaCl2 post-treatment

Mn2+-doped CsPbCl3 perovskite nanocrystals (NCs) exhibit a significant Stokes shift and emit bright orange-red light, making them promising candidates for optoelectronic devices. However, these NCs are prone to surface defects during multiple purification steps, which hinder the transfer of energy from excitons to Mn2+ and reduce luminescence efficiency. Herein, we introduce a post-treatment method using a CaCl2 ethanol solution to passivate surface defects in Mn2+-doped CsPbCl3 NCs. This treatment enhances the energy transfer from excitons to Mn2+ and boosts luminescence performance, achieving a photoluminescence quantum yield of up to 96 % and maintaining stability through several washing cycles. In this process, Ca2+ ions, as a Lewis acid, replace oleic acid molecules on NC surfaces, leading to stronger binding. The Cl− from the CaCl2 solution fill vacancies on NC surfaces, effectively passivating surface defects. This reduces non-radiative recombination centers, increases energy transfer efficiency from 83 % to 87 %, and accelerates the radiative recombination rates of excitons and Mn2+. The post-treated NCs also retain their PL against continuous heat and ultraviolet irradiation. The passivation of surface defects on perovskite NCs achieved through this post-processing strategy enhances the energy transfer from excitons to doped ions, providing guidance for achieving efficient and stable doped perovskite NCs.

Oleic acid treatment of rice grains reduces the starch digestibility: Formation, binding state and fine structure of starch-lipid complexes

Rice contains abundant starch and contributes to a rapid rise in postprandial blood glucose levels. Hence, it is crucial to directly modify rice grains for resistant starch (RS) content elevation while preserving their morphology. In this study, rice grains were treated with 6%–18% concentrations of oleic acid (OA) and 8–20 h of soaking time to promote the formation of starch-lipid complexes, thereby reducing rice digestibility. In OA-treated rice, the OA molecules exist in three binding states. OA-treated rice exhibited a significantly higher complexation index and OA content than natural rice. RS content increased from 20.50% to 32.46%. X-ray diffraction and NMR spectroscopy revealed the development of amylose-OA complexes within the rice grains and a V-crystalline structure of up to 3.62%. Raman spectroscopy and thermogravimetric analysis showed enhanced molecular ordering and structural stability of rice starch. Overall, OA treatment effectively promotes RS formation within rice grains, consequently reducing rice digestibility.

Macroscale Superlubricity with High Pressure Enabled by Partially Oxidized Violet Phosphorus for Engineering Steel

AbstractAs a novel cross‐structured 2D material, violet phosphorus (VP) promises to further develop the dynamic performance, energy efficiency, and service lifetime of mechanical components owing to its high strength and toughness, large carrier mobility, wide bandgap, and good friction‐reducing properties. In this work, the partially oxidized violet phosphorus nanosheets (oVP) are synthesized and employed as the lubricating additives in the poly alpha olefin (PAO) oil environment with less oleic acid (OA) improver, which can trigger the macroscale superlubricity on the diamond‐like carbon (DLC) film deposited steel surface at high loading pressures (>800 MPa) and sliding speeds (>0.1 m s−1). The friction coefficient (COF) of the steel‐DLC tribopair lubricated by the oVP‐PAO oil can reduce down to 0.0064 with little wear. At the high‐pressure sliding interface, the force‐thermal coupling action during the running‐in process promotes the cleavage and recombination of oVP nanosheets and OA molecules to form a reliable chemical adsorption tribofilm mainly composed of phosphorus oxides and amorphous carbon, which prevents the original asperities from direct contact and provides an ultralow shear strength. These findings suggest a new method to achieve macroscale oil‐based high‐pressure superlubricity for engineering steel through the lubrication and catalyzation effects of oVP.

Properties of waste vegetable oil recycled asphalt-binder: a molecular simulation study

ABSTRACT The aging of asphalt-binder during long-term use is an important reason for the decline in road performance of asphalt mixtures. In this study, waste vegetable oil (fried for 1-2h) was investigated as a rejuvenator of asphalt-binder. The optimisation effect of waste vegetable oil on the performance of asphalt-binder with different aging degrees (RTFOT, PAV15/20/48h) was evaluated by testing their conventional physical properties, high-temperature properties, and low-temperature properties. The molecular dynamics method was used to construct models, and the diffusion properties, solubility properties, adsorption energy, and asphaltene aggregation were calculated. The influences of linoelaidic acid and oleic acid molecules on aged asphalt-binder molecules were evaluated. The changes in the functional groups of the aged asphalt-binder after the addition of waste vegetable oil were analyzed by infrared spectrometry, and the changes in the microstructure of the aged asphalt-binder surface were observed by scanning electron microscopy. The results revealed that waste vegetable oil could regenerate aged asphalt-binder and significantly improve their physical and high-/low-temperature properties. Waste vegetable oil molecules are compatible with aged asphalt-binder molecules, improve their diffusion behaviour, enhance their adsorption capacity, and slightly reduce the aggregation of asphaltenes. Overall, waste vegetable oil shows great potential for the regeneration of aged asphalt-binder.

Oleic acid-modified layered double hydroxide for Pickering emulsions: (I) Interfacial properties

Layered double hydroxides (LDHs) are one type of potential emulsifiers for Pickering emulsions. Surface modification can regulate their surface properties, thereby affecting their emulsifying behavior. However, there is still a lack of full understanding of the impact of surface modification on their surface properties. In the current work, one Mg3Al-Cl LDH was modified using oleic acid (OA), obtaining six OA-modified products with different OA loadings. Their contact angles and relative dielectric constants were determined, and their surface properties including the interfacial free energies (γ) and solubility parameters (δ) were then estimated from the data. Their apparent molar volumes were estimated using the γ and δ data. OA molecules are coated on the LDH surface via the bidentate bonding mode to form monolayers. The OA modification has no obvious impact on the structure and morphology of LDH particles, but can significantly affect their surface properties. This work provides a better understanding of the dependence of surface properties of LDHs on the surface modification.

Controlled synthesis and tuned fluorescence properties of NaGdF4:Yb, Er up-conversion nanocrystals through one-step hydrothermal approach

The properties of NaGdF4:Yb, Er nanomaterials tuned by synthesis conditions have always been one of the research hotspots in the field of upconversion nanomaterials. In this work, NaGdF4:Yb, Er upconversion nanomaterials capped with oleic acid (OA) molecules were prepared by one-step hydrothermal method. Controlling the fluorescence properties of NaGdF4:Yb, Er nanomaterials by changing the synthesis conditions were principally investigated. The results showed that the crystalline state of the as-prepared upconversion nanomaterials tended to be intact and fluorescence emission capability enhanced when the reaction temperature increased from 140 °C to 160 °C, 180 °C and the reaction time extended from 6 h to 18 h. From 0.00 mmol to 0.75, 2.25, 5.00, 8.75, 12.50, 17.50 mmol of sodium hydroxide amount, the synthesized upconversion nanoparticles (UCNPs) transferred from orthorhombic GdF3 to hexagonal β-NaGdF4. And when the amount of sodium hydroxide was 2.25 mmol, the as-prepared nanoparticles exhibited stronger luminescence intensity. The ratio of Re3+ (Gd3+:Yb3+:Er3+) could also affect the properties of the as-prepared UCNPs. The nanomaterials emitted relatively stronger fluorescence when the ratio among Gd3+, Yb3+, Er3+ was 78:20:2. This work provides solid foundation for further theoretical study and practical application of NaGdF4:Yb, Er nanomaterials.

The Narrow Synthetic Window for Highly Homogenous InP Quantum Dots toward Narrow Red Emission.

Low-toxicity InP-based quantum dots (QDs) exhibit potential for replacing Cd/Pb-containing QDs in the visible and near-infrared regions. Despite advancements, further improvement relies on synthesizing homogeneous InP QDs to achieve a high color purity. In a commonly employed two-step "seed-mediated" synthetic approach, we demonstrate the high sensitivity of InP seed sizes and size distribution to the quantities of trioctylphosphine (TOP) and tris(trimethylsilyl)phosphine [(TMS)3P], attributed to the process of "self-focusing of size distribution" and enhanced reactivity of In-oleate through coordination with TOP. During growth, the processes of size focusing and defocusing are modulated by the accumulation of oleic acid and TOP molecules, as well as the amount of (TMS)3P in the growth precursor, which may relate to the dissolution process of InP magic size clusters. Through precise control, the best valley/depth ratio of InP QDs was 0.52 at the first absorption peak at 571 nm, resulting in luminescence with a full width at half-maximum of 35 at 620 nm with an absolute photoluminescence quantum yield around 90% after heteroepitaxial growth with ZnSe and ZnS shells.

Surface-Modified LDH Nanosheets with High Dispersibility in Oil for Friction and Wear Reduction.

Surface and interfacial engineering of nanomaterials is essential for improving dispersion stability in liquids. In this study, we report that oleic acid (OA)- and stearic acid (SA)-functionalized layered double hydroxide (LDH) nanosheets as lubricant additives can achieve high dispersion and reduce friction and wear. LDH is a typical layered structure, and OA and SA are long-chain organic molecules that are not only compatible with base oils but also act as friction-reducing agents. The OA and SA molecules were branched onto ZnMgAl LDH nanosheets using dehydration condensation between the exposed OH groups on the surface of LDH and the COOH groups on the OA and SA molecules. Compared with that of the pristine ZnMgAl LDH, the dispersion of OA-ZnMgAl LDH and SA-ZnMgAl LDH was significantly improved. The surface-modified LDH exhibited superior tribological properties and great stability due to the synergistic lubrication effect between OA, SA, and LDH. Even at an ultralow concentration (0.15 wt %), the coefficient of friction and wear volume were reduced by ∼65 and ∼99%, respectively, compared to those of the base oil. Due to the green and simple synthesis method and excellent tribological properties, surface-functionalized LDH has enormous possibilities for future industrial applications.

Influence of arylalkyl amines on the formation of hybrid CsPbBr3 nanocrystals via a modified LARP method.

Perovskite nanocrystals have attracted much attention in the last ten years due to their different applications, especially in the photovoltaic domain and LED performance. In this large family of perovskite nanocrystals, CsPbBr3 nanocrystals are attractive nanomaterials because they are good candidates for obtaining green emissions and exploring new synthesis routes. In this context, controlling the nanometric scale's morphology, particularly the size and monodispersity, is fundamental for exploring their photophysical properties and final applications. Currently, the nanometric size of nanocrystals is ensured by the presence of oleic acid and oleylamine molecules, in using Hot Injection (HI) or ligand-assisted reprecipitation (LARP) methods. If oleic acid plays a fundamental role, oleylamine can be easily substituted by other amino molecules, opening the way for the functionalization of CsPbBr3 nanocrystals and the obtention of new hybrid perovskite nanocrystal families. In this article, we describe the synthesis, by soft chemistry, of a new family of hybrid organic-inorganic CsPbBr3 nanocrystals, functionalized by aryl-alkylamine (AAA) molecules, through the modified LARP method. We highlight the mechanism for cutting submicron crystals into nanocrystals, using aryl-alkylamine molecules like scissors. The impact of these amino molecules on the final nanocrystals leads to different nanocrystal morphologies (nanocubes, nanosheets, or nanorods) and structures (monoclinic, rhombohedral, or tetragonal). In addition, this modified LARP method highlights, under certain experimental conditions, an unexpected formation of PbO ribbons.

Onion-like carbon nanoparticles as additives in lubricant oil deform inelastically during the wear testing for improved lubrication performances

Nano-carbon has been extensively investigated as an additive to lubricant oil for improved performance. It is still far from a final verdict as to how the physicochemical features of the carbon nanomaterials affect their lubrication efficacy. Here we report the use of onion-like carbon (OLC) particles with the size of 5–10 nm as additives to lubricant oil, and their role in regulating the lubrication is elucidated through characterizing the wear-induced changes to their physiochemistry. Multiple loads are chosen for the wear testing using the four-ball friction tester. Stable dispersion of the OLC particles in lubricant oil was attained by pre-coating the particles with oleic acid molecules. Results showed that the oil with the treated OLC particles of 0.125 wt% reduced the wear scar by 30 % in diameter and the wear volume by 77 %. It was surprisingly noted that incorporation of the OLC nanoparticles particularly alleviated the heavy loading wear by remarkably reducing the friction coefficient. Raman spectroscopy characterization suggested intact chemistry of the particles after the wear testing. However, curvature changes of the particles were seen as revealed by high resolution transmission electron microscopy after the wear testing, indicating inelastic deformation of the particles triggered by the wear-squeezing.

Effect of oleic acid on morphologies of BaTi5O11 nanocrystals synthesized by hydrothermal method

Abstract BaTi5O11 nanocrystals were synthesized by a hydrothermal method, and the effect of oleic acid (OA) in the Ba–Ti precursors on morphologies of BaTi5O11 nanocrystals was investigated. As the OA/(Ba2+ + Ti4+) molar ratio ranged from 0 to 8, single-phase BaTi5O11 nanocrystals were synthesized at 260 °C for 20 h. When OA reagent was not added to the precursors, rice-like BaTi5O11 nanocrystals were obtained. As the OA/(Ba2+ + Ti4+) molar ratio was 1, elongated lath-like BaTi5O11 nanocrystals were synthesized with the width of about 130 nm, thickness of about 50 nm and length of about 400 nm. With increasing the OA/(Ba2+ + Ti4+) molar ratio from 1 to 6, the grain size of elongated lath-like BaTi5O11 nanocrystals gradually decreased. As the OA content increased, the amount of adsorbed OA molecules on the surface of Ti(OH) x nucleus increased and hindered the reaction of Ba2+ ions with Ti(OH) x nucleus, which caused the decrease of grain size of lath-like BaTi5O11 nanocrystals. When the BaTi5O11 nanocrystals were synthesized at OA/(Ba2+ + Ti4+) molar ratio of 1, they had the largest dielectric constant (ε r) of 40.9 at 5 GHz.

DNA aptamer functionalized monodisperse Eu/Mn-WH nanoparticle for in vivo magnetic resonance and fluorescence imaging

Because of its biocompatibility, non-immunogenicity, bioactivity, and biodegradability, Whitlockite (WH) plays a crucial role in biomedical fields. However, a layer of oleic acid molecules is attached to the surface of WH synthesized by liquid–solid–solution (LSS) method, which hinders its application in biomedicine field. In this paper, we successfully synthesized hydrophilic nanoparticles with bright red fluorescence and excellent magnetic properties (Eu/Mn-WH-Apt NPs) via the ions doping and ligand exchange strategy. In vitro/vivo experiments show that Eu/Mn-WH-Apt nanoparticles have excellent biocompatibility, dispersion stability, tumor targeting ability, satisfactory fluorescence, and magnetic resonance imaging capabilities. Therefore, the prepared multifunctional Eu/Mn-WH-Apt NPs may provide a new strategy and insights for accurately diagnosing clinical cancer.

Study on the extraction and separation of precious metals from wastewater using a hydrophobic deep eutectic solvent

Efficient and sustainable recovery of precious metals from the acidic leaching solution of solid waste is considered to be the main solution to the scarcity of precious metal resources. In this study, a hydrophobic deep eutectic solvent (HDES) was synthesized using trioctylmethylammonium chloride (N263) and oleic acid (OA). HDES was then used for the efficient recovery of Ir, Pt, Ru, and Rh from leaching solution containing precious metals. The effects of different molar ratios between N263 and OA, the initial pH of the aqueous phase, the oscillation time, and the phase ratio O/A of the extraction process were investigated. The organic phases were characterized analytically using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, and electrospray ionization–mass spectrometry to further investigate the reaction mechanisms of the extraction process. The single-stage extraction percentages of Ir(IV), Ru(III), Pt(IV), and Rh(III) ions were 97.57%, 94.26%, 99.55%, and 15.1%, respectively. The high saturation extraction capacity of HDES enabled a high precious metal load, reaching 18.44 g L−1. Hydrogen bonds were formed between Cl-, which was bound by electrostatic force in the N263 structure, and H in the -COOH group in the OA molecule. During the extraction process, metal chloride complex ions replaced Cl- and entered the organic phase as 2[C17H33-COOH···N263+]IrCl62-, 3[C17H33-COOH···N263+]RuCl63-, 2[C17H33-COOH···N263+]PtCl62-, and 3[C17H33-COOH···N263+]RhCl63-. After scrubbing for effective removal of Cu and Fe in the loaded organic phase, different systems were used for stripping. The stripping percentage of precious metal ions reached more than 96.3%, providing efficient separation of the four precious metals from wastewater.

Raman and FTIR spectroscopy experimental and theoretical in magnetic nanoemulsion from Carapa Guianensis Aublet

This work brings Raman and Fourier transform infrared (FTIR) spectroscopy as a proposal for a vibrational characterization of Carapa Guianensis Aublet essential oil in natura and polymerized and of magnetic nanoemulsion. Calculation of computational chemistry based on the method density functional theory with B3LYP functional and 6-311+G(d,p) base set parameters was used to obtain theoretical frequencies and vibrational signatures of the oleic acid molecule. Results of Raman and Fourier transform infrared spectroscopy confirm bands of Carapa Guianensis Aublet essential oil present in polymerized oil and magnetic nanoemulsion studied. The density functional theory method shows that the bands 1099 cm-1, 1714 cm-1 and 1812 cm-1 explain the presence of vibrational modes of oleic acid in the samples. The density functional theory brought good conformation to the chosen molecule.

Production of Human Milk Fat Substitutes by Lipase-Catalyzed Acidolysis: Immobilization, Synthesis, Molecular Docking and Optimization Studies

Human milk fat (HMF) triacylglycerols (TAGs) mainly contain palmitic acid esterified at the sn-2 position while oleic and other unsaturated fatty acids are located at positions sn-1,3. This study aimed at the production of HMF substitutes (HMFS) by lipase-catalyzed acidolysis of tripalmitin with oleic acid, in a solvent-free medium. Burkholderia cepacia lipase (BCL) was immobilized in silica (prepared with protic or aprotic ionic liquids) by covalent binding or encapsulation and used as biocatalyst. The supports and immobilized biocatalysts were characterized by FTIR, TGA, and SEM. Molecular docking analysis showed that BCL preferentially attacks oleic acid rather than tripalmitin, due to the lower free energy of hydrophobic binding with this acid (−6.5 kcal·mol−1) than with tripalmitin (5.4 kcal·mol−1). Therefore, the tripalmitin attack by BCL and subsequent HMFS production only occurs after the binding to most of the oleic acid molecules. The highest acidolysis activity was obtained with BCL immobilized by covalent binding in prepared silica with aprotic ionic liquid. A central composite rotatable design, as a function of temperature (58–72 °C) and oleic acid/tripalmitin molar ratio (MR = 2:1–6.8:1), was performed for acidolysis optimization. Under optimized conditions (58 °C and MR = 4:1 or 60 °C and MR = 2:1), the oleic acid incorporation of 28 mol.% was achieved after 48 h.

Superlubricity induced by partially oxidized black phosphorus on engineering steel

Macroscale superlubricity has attracted increasing attention owing to its high significance in engineering and economics. We report the superlubricity of engineering materials by the addition of partially oxidized black phosphorus (oBP) in an oleic acid (OA) oil environment. The phosphorus oxides produced by active oxidation exhibit lower friction and quick deposition performance compared to BP particles. The H-bond (-COOH⋯O-P, or -COOH⋯O=P) formed between P-O bond (or P=O) and OA molecule could benefit the lubricating state and decrease the possibility of direct contact between rough peaks. The analysis of the worn surface indicates that a three-layer tribofilm consisting of amorphous carbon, BP crystal, and phosphorus oxide forms during the friction, which replaces the shear interface from the steel/steel to carbon—oBP/carbon—oBP layer and enables macroscale superlubricity.

Enhancing Charge Carrier Transport in the Carbon-Electrode-Based CsPbI2Br Perovskite Solar Cells via I/Br Homogenization Process Modulation and Oleic Acid Surface Passivation

The carbon-electrode-based CsPbI2Br perovskite solar cells (C-PSCs) are promising photovoltaic technology because of their enhanced stability and low cost. However, the CsPbI2Br film suffers from uneven surface morphology with stripes and the defect-rich surface, which are detrimental to the charge carrier transport between perovskite and carbon. Here, we demonstrate that the formation of stripes is directly related to the I/Br homogenization process during annealing. By introducing a pre-annealing treatment before high temperature annealing, the I/Br homogenization process is modulated and the stripe is successfully wiped off. Besides, enhanced charge carrier transport in the C-PSCs is achieved. Oleic acid (OA) is then introduced to modify the stripe-free perovskite film surface. It is revealed that the carboxyl group in the OA molecule can passivate the undercoordinated Pb ions, leading to further improved charge carrier transport. Eventually, a power conversion efficiency (PCE) of 15.57% is achieved, which is among the highest PCE for the CsPbX3-based C-PSCs. This work demonstrates that combining surface planarization with surface passivation is an effective strategy for developing highly efficient C-PSCs.

Tribological properties of metal-organic framework nanosheets functionalized by oleic acid

<p indent="0mm">Terephthalic acid and copper acetate were used as raw materials, and copper-based metal-organic framework (Cu-MOF) nanosheets were synthesized by ultrasonic-assisted self-assembly. Afterward, oleic acid (OA) molecules were successfully modified on the surface of Cu-MOF by ultrasonic treatment to acquire Cu-MOF@OA nanosheets. The morphology of Cu-MOF@OA maintained its sheet structure; however, the size of the nanosheets was reduced, and the agglomeration problem was considerably alleviated compared with Cu-MOF nanosheets. The Cu-MOF@OA nanosheets exhibited good dispersion stability in <sc>500 N</sc> base oil. The tribological tests indicated that Cu-MOF@OA showed the best tribological properties at the addition concentration of 1.0 wt.%. Moreover, the friction coefficient and wear volume were reduced to 3/5 and 1/6 of the base oil, respectively. Finally, scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the morphology and characteristic elements of wear scar lubricated by Cu-MOF@OA nanosheets and explore the lubrication mechanism. The results indicated that complex tribochemical reactions occur among Cu-MOF@OA, base oil, and iron substrate under the action of load and shear stress during the friction experiment, forming a tribofilm composed of nitrogenous substances, carbonaceous substances, and iron oxides, which reduce the friction and wear of metal surfaces.

Loading of alpha-tocopherol in a nonionic microemulsion: Phase behavior and structural characteristics

In this research, we present a systematic analysis of events inside single phase region of a nonionic microemulsion (ME) during incorporation of water and α-tocopherol (AT, a hydrophobic payload). The formulation was developed using α-tocopherol polyethylene glycol succinate, ethanol and oleic acid, respectively, as surfactant, cosurfactant and oil phase. Phase boundary was constructed using water titration method. Behavior of the formulation was studied at two points within the phase boundary. These points carried identical surfactant-cosurfactant mixture (Smix) but different oil content (labeled as DL1: 5% oil and DL2: 10 % oil). These compositions were sequentially challenged with water (in 5 % increments) and examined using dynamic light scattering, small angle neutron scattering and rheological techniques. Contrary to the reports on MEs composed with ionic components, we did not observe any significant effect of AT solubilization upon formulation’s microstructure or phase boundary at a dose of 15 mg/mL. However, swollen aggregates appeared as secondary peaks in light scattering data during water addition. We attribute it to reduction in Smix – oil ratio. As a result of this, oleic acid molecules were exposed to surfactant-poor aqueous phase. Similar observations were recorded at higher oil level. Rheological studies indicated towards weak association among hydrated droplets as a result of which the dispersion exhibited shear-thinning behavior. Despite these changes, the formulation could retain its isotropicity. The information on microstructural changes can be valuable in maximizing the payload inside microemulsion formulations.

Synergistic lubrication effects and tribological properties of graphene/oil-based lubricant systems

Graphene exhibits great potential as an additive to enhance the anti-wear and friction reduction capacity of moving mechanical components in a synergistic mechanism with the base oil. This paper considers the effect of different factors such as the number of base oil molecules, graphene content, normal load, sliding velocity and the presence of graphene. The synergistic mechanism of graphene and base oil is investigated by experiments and molecular dynamics (MD) simulations. The results show that the friction and wear reduction is due to the formation of the load-supporting graphene layers and sufficient base oil molecules between Fe slabs. Graphene can stably adsorb on the rubbing surfaces lubricated by the base oil, confirming that graphene can form a physical deposition film on rubbing surfaces. Low friction and wear can be achieved with higher sliding velocity and lower load. Furthermore, compared to the sliding velocity, the load significantly affects the mean square displacement of base oil and oleic acid molecules. These outcomes provide a better understanding of the tribological properties of graphene as a lubricant additive.