The purpose of this study is to explore the emulsion liquid membrane stability for acetaminophen (ACTP) removal from aqueous solution. In this work, the membrane phase was prepared by dissolving trioctylamine (TOA) with kerosene and Span80. The stability of the emulsion in terms of emulsion size, membrane breakage, and its efficiency in removing ACTP was considered for the optimization of parameters. Investigation on the stability of emulsion was carried out by manipulating the concentration of stripping agent, agitation speed, extraction time, and treat ratio. The best condition to produce a very stable emulsion was achieved at 0.1 M of stripping agent concentration, with 300 rpm of agitation speed for 3 min of extraction time with a treat ratio of 3:1. Eighty-five percent of ACTP successfully stripped into the emulsion with minimum membrane breakage of 0.17% through this experiment.
Chromobacterium violaceum (C. violaceum) is a Gram-negative, rod-shaped facultatively anaerobic bacterium implicated with recalcitrant human infections. Here, we evaluated the anti-QS and antibiofilm activities of ethyl acetate extracts of Passiflora edulis (P. edulis) on the likely inactivation of acyl-homoserine lactone (AHL)-regulated molecules in C. violaceum both by in vitro and in silico analyses. Our investigations showed that the sub-MIC levels were 2, 1, and 0.5 mg/mL, and the concentrations showed a marked reduction in violacein pigment production by 75.8, 64.6, and 35.2%. AHL quantification showed 72.5, 52.2, and 35.9% inhibitions, inhibitions of EPS production (72.8, 36.5, and 25.9%), and reductions in biofilm formation (90.7, 69.4, and 51.8%) as compared to a control. Light microscopy and CLSM analysis revealed dramatic reduction in the treated biofilm group as compared to the control. GC-MS analysis showed 20 major peaks whose chemical structures were docked as the CviR ligand. The highest docking score was observed for hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester bonds in the active site of CviR with a binding energy of -8.825 kcal/mol. Together, we found that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester remarkably interacted with CviR to inhibit the QS system. Hence, we concluded that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester of P. edulis could likely be evaluated for treating C. violaceum infections.
For the first time, the fabrication of novel nanorods by the addition of polyaniline (PANI) to polyethylene oxide (PEO) and polyvinyl alcohol (PVA) polymers through electrospinning method is investigated. Field emission scanning electron microscopy observations reveal the formation of nanofibers and nanorods having diameters in the range of 26.87-139.90 nm and 64.11-122.40 nm, respectively, and lengths in the range of 542.10 nm to 1.32 μm. Photoluminescence (PL) analysis shows the presence of peaks which are characteristic of isotactic polymers (363-412, 529-691 nm), 412-529 nm for PVA/PEO and 363-691 nm for PVA/PEO/PANI. PL spectra also show peak bonding at a wavelength of 552 nm. Manufacture of nanorods by electrospinning method gives better options for controlling the diameter and length of nanorods.
One of the techniques to increase oil recovery from hydrocarbon reservoirs is the injection of low salinity water. It is shown that the injection of low salinity water changes the wettability of the rock. However, there are argumentative debates concerning low salinity water effect on changing the wettability of the oil/brine/rock system in the oil reservoirs. In this regard, molecular dynamics simulation (MDS) as a tool to simulate the phenomena at the molecular level has been used for more than a decade. In this study, the Zisman plot (presented by KRUSS Company) was simulated through MDS, and then, contact angle experiments for n-decane interactions on the Bentheimer substrate in the presence of different concentrations of sodium ions were conducted. MDS was then used to simulate experiments and understand the wettability trend based on free-energy calculations. Hereafter, a new model was developed in this study to correlate free energies with contact angles. The developed model predicted the experimental results with high accuracy (R2 ∼ 0.98). A direct relation was observed between free energy and water contact angle. In contrast, an inverse relation was noticed between the ion concentration and the contact angle such that an increase in the ion concentration resulted in a decrease in the contact angle and vice versa. In other terms, increasing brine ionic concentrations in the presence of n-decane is linked to a decrease in free energies and an increase in the wetting state of a sandstone. The comparison between the developed model's predicted contact angles and experimental observations showed a maximum deviation of 14.32%, which is in satisfactory agreement to conclude that MDS can be used as a valuable and economical tool to understand the wettability alteration process.
Mn3O4 is considered to be a promising anode material for sodium-ion batteries (SIBs) because of its low cost, high capacity, and enhanced safety. However, the inferior cyclic stability of the Mn3O4 anode is a major challenge for the development of SIBs. In this study, a one-step solvothermal method was established to produce nanostructured Mn3O4 with an average particle size of 21 nm and a crystal size of 11 nm. The Mn3O4 obtained exhibits a unique architecture, consisting of small clusters composed of numerous tiny nanoparticles. The Mn3O4 material could deliver high capacity (522 mAh g-1 at 100 mA g-1), reasonable cyclic stability (158 mAh g-1 after 200 cycles), and good rate capability (73 mAh g-1 at 1000 mA g-1) even without further carbon coating, which is a common exercise for most anode materials so far. The sodium insertion/extraction was also confirmed by a reversible conversion reaction by adopting an ex situ X-ray diffraction technique. This simple, cost-effective, and environmentally friendly synthesis technique with good electrochemical performance shows that the Mn3O4 nanoparticle anode has the potential for SIB development.
The research presented here investigates the reaction mechanism of wollastonite in situ mineral carbonation for carbon dioxide (CO2) sequestration. Because wollastonite contains high calcium (Ca) content, it was considered as a suitable feedstock in the mineral carbonation process. To evaluate the reaction mechanism of wollastonite for geological CO2 sequestration (GCS), a series of carbonation experiments were performed at a range of temperatures from 35 to 90 °C, pressures from 1500 to 4000 psi, and salinities from 0 to 90,000 mg/L NaCl. The kinetics batch modeling results were validated with carbonation experiments at the specific pressure and temperature of 1500 psi and 65 °C, respectively. The results showed that the dissolution of calcium increases with increment in pressure and salinity from 1500 to 4000 psi and 0 to 90000 mg/L NaCl, respectively. However, the calcium concentration decreases by 49%, as the reaction temperature increases from 35 to 90 °C. Besides, it is clear from the findings that the carbonation efficiency only shows a small difference (i.e., ±2%) for changing the pressure and salinity, whereas the carbonation efficiency was shown to be enhanced by 62% with increment in the reaction temperature. These findings can provide information about CO2 mineralization of calcium silicate at the GCS condition, which may enable us to predict the fate of the injected CO2, and its subsurface geochemical evolution during the CO2-fluid-rock interaction.
With increased awareness on the importance of gloves arising from the COVID-19 pandemic, people are expected to continue using them even after the pandemic recedes. This scenario in a way increased the rubber solid waste disposal problem; therefore, the production of biodegradable gloves may be an option to overcome this problem. However, the need to study the shelf life of biodegradable gloves is crucial before commercialization. There are well-established models to address the failure properties of gloves as stated in the American Society for Testing and Material (ASTM) D7160. In this study, polysaccharide-based material-filled natural rubber latex (PFNRL) gloves, which are biodegradable gloves, were subjected to an accelerated aging process at different temperatures of 50-80 °C for 1-120 days. Prediction models based on Arrhenius and shift factors were used to estimate the shelf life of the PFNRL gloves. Based on the results obtained, the estimated time for the PFNRL gloves to retain 75% of their tensile strength at shelf temperature (30 °C) based on Arrhenius and shift factor models was 2.8 years. Verification on the activation energy based on the shift factor model indicated that the shelf life of PFNRL gloves is 2.9 years, which is only a 3.6% difference. The value obtained is aligned with the requirement in accordance with ASTM D7160, which states that only up to a maximum of 3 years' shelf life is allowed for the gloves under accelerated aging conditions.
The brain neurotransmitter level is associated with the pathology of various neurodegenerative diseases, and age-dependent increase in the blood level of vasopressin, human brain monoamine oxidase (hMAO) level, oxidative stress, and imbalance in aminergic signaling are common disease-modifying factors leading to various neurodegenerative disorders. Based on the reports of emodin in hMAO inhibition and antagonist effect on the vasopressin V1A receptor, in this study we synthesized six emodin derivatives and evaluated their effects on MAO activity and G protein-coupled receptors. Among them, 4-hydroxyemodin and 5-hydroxyemodin were potent inhibitors of hMAO, and 2-hydroxyemodin and 5-hydroxyemodin were good V1AR antagonists. In silico molecular docking simulation revealed that the hydroxyl group at C2, C4, and C5 of the respective compounds interacted with prime residues, which corroborates the in vitro effect. Likewise, these three derivatives were predicted to have good drug-like properties. Overall, our study demonstrates that the hydroxyl derivatives of emodin are multi-target-directed ligands that may act as leads for the design and development of a therapy for central nervous system disorders.
Partial least squares discriminant analysis (PLS-DA) is a well-known technique for feature extraction and discriminant analysis in chemometrics. Despite its popularity, it has been observed that PLS-DA does not automatically lead to extraction of relevant features. Feature learning and extraction depends on how well the discriminant subspace is captured. In this paper, discriminant subspace learning of chemical data is discussed from the perspective of PLS-DA and a recent extension of PLS-DA, which is known as the locality preserving partial least squares discriminant analysis (LPPLS-DA). The objective is twofold: (a) to introduce the LPPLS-DA algorithm to the chemometrics community and (b) to demonstrate the superior discrimination capabilities of LPPLS-DA and how it can be a powerful alternative to PLS-DA. Four chemical data sets are used: three spectroscopic data sets and one that contains compositional data. Comparative performances are measured based on discrimination and classification of these data sets. To compare the classification performances, the data samples are projected onto the PLS-DA and LPPLS-DA subspaces, and classification of the projected samples into one of the different groups (classes) is done using the nearest-neighbor classifier. We also compare the two techniques in data visualization (discrimination) task. The ability of LPPLS-DA to group samples from the same class while at the same time maximizing the between-class separation is clearly shown in our results. In comparison with PLS-DA, separation of data in the projected LPPLS-DA subspace is more well defined.
Nitrogen-infused wet oxidation at different temperatures (400-1000 °C) was employed to transform tantalum-hafnia to hafnium-doped tantalum oxide films. High-temperature wet oxidation at 1000 °C marked an onset of crystallization occurring in the film, accompanied with the formation of an interfacial oxide due to a reaction between the inward-diffusing hydroxide ions, which were dissociated from the water molecules during wet oxidation. The existence of nitrogen has assisted in controlling the interfacial oxide formation. However, high-temperature oxidation caused a tendency for the nitrogen to desorb and form N-H complex after reacting with the hydroxide ions. Besides, the presence of N-H complex implied a decrease in the passivation at the oxide-Si interface by hydrogen. As a consequence, defect formation would happen at the interface and influence the metal-oxide-semiconductor characteristics of the samples. In comparison, tantalum-hafnia subjected to nitrogen-infused wet oxidation at 600 °C has obtained the highest dielectric constant, the largest band gap, and the lowest slow trap density.
The objective of this study is to investigate the intermolecular interactions between the surfactants and the fractions of heavy crude oils. Two possible interactions were considered; polar and ionic interactions for two heavy crude oil-surfactant systems, and 20 surfactant-steam flooding tests were conducted on these crudes by testing nine surfactants (three anionic, three cationic, and three nonionic) with different tail lengths and charged head groups. The performance differences observed in each core flood were discussed through the additional analyses. To explain polar interactions, the pseudo blends of crude oil fractions (fractionation of saturates, aromatics, resins, and asphaltenes) were exposed to the surfactant solutions under vapor and liquid water conditions and their mutual interactions were visualized under an optical microscope. To explain ionic interactions, the charges on asphaltene surfaces were analyzed by zeta potential measurements before and after core flood tests on both the produced and the residual oil asphaltenes. The addition of surfactants improved the oil recovery when compared to steam injection alone. However, different oil recoveries were obtained with different surfactants. Further analyses showed that asphaltenes are key and the interaction of asphaltenes with other crude oil fractions or surfactants determines the success of surfactant-steam processes. The polar interactions favor the emulsion formation more; hence, if the polar interactions are more dominant than the ion interactions in the overall crude oil-surfactant system, the surfactant flooding process into heavy oil reservoir became more successful.
Density functional theory computational investigation was performed to study the electronic structures, muon sites, and the associated hyperfine interactions in [Au25(SR)18]0 and [Au25(SeR)18]0 where R is phenylethane. The calculated electronic structures show inhomogeneous spin density distribution and are also affected by different ligands. The two most stable muon sites near Au atoms in the thiolated system are MAu11 and MAu6. When the thiolate ligands were replaced by selenolate ligands, the lowest energy positions of muons moved to MAu6 and MAu5. Muons prefer to stop inside the Au12 icosahedral shell, away from the central Au and the staple motifs region. Muonium states at phenyl ring and S/Se atoms in the ligand were found to be stable and the Fermi contact fields are much larger as compared to the field experienced by muons near Au atoms.
A gold nanoparticle (AuNP) has a localized surface plasmon resonance peak depending on its size, which is often utilized for surface-enhanced Raman scattering (SERS). To obtain information on the cholesterol (Chol)-incorporated lipid membranes by SERS, AuNPs (5, 100 nm) were first functionalized by 1-octanethiol and then modified by lipids (AuNP@lipid). In membrane surface-enhanced Raman spectroscopy (MSERS), both signals from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and Chol molecules were enhanced, depending on preparation conditions (size of AuNPs and lipid/AuNP ratio). The enhancement factors (EFs) were calculated to estimate the efficiency of AuNPs on Raman enhancement. The size of AuNP100nm@lipid was 152.0 ± 12.8 nm, which showed an surface enhancement Raman spectrum with an EF2850 value of 111 ± 9. The size of AuNP5nm@lipid prepared with a lipid/AuNP ratio of 1.38 × 104 (lipid molecule/particle) was 275.3 ± 20.2 nm, which showed the highest enhancement with an EF2850 value of 131 ± 21. On the basis of fluorescent probe analyses, the membrane fluidity and polarity of AuNP@lipid were almost similar to DOPC/Chol liposome, indicating an intact membrane of DOPC/Chol after modification with AuNPs. Finally, the membrane properties of AuNP@lipid systems were also discussed on the basis of the obtained MSERS signals.
The antipyretic potential of viscosine, a natural product isolated from the medicinal plant Dodonaea viscosa, was investigated using yeast-induced pyrexia rat model, and its structure-activity relationship was investigated through molecular docking analyses with the target enzymes cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1). The in vivo antipyretic experiments showed a progressive dose-dependent reduction in body temperatures of the hyperthermic test animals when injected with viscosine. Comparison of docking analyses with target enzymes showed strongest bonding interactions (binding energy -17.34 kcal/mol) of viscosine with the active-site pocket of mPGES-1. These findings suggest that viscosine shows antipyretic properties by reducing the concentration of prostaglandin E2 in brain through its mPGES-1 inhibitory action and make it a potential lead compound for developing effective and safer antipyretic drugs for treating fever and related pathological conditions.
A combinative effect of two or more individual material properties, such as lattice parameters and chemical properties, has been well-known to generate novel nanomaterials with special crystal growth behavior and physico-chemical performance. This paper reports unusually high catalytic performance of AgPt nanoferns in the hydrogenation reaction of acetone conversion to isopropanol, which is several orders higher compared to the performance shown by pristine Pt nanocatalysts or other metals and metal-metal oxide hybrid catalyst systems. It has been demonstrated that the combinative effect during the bimetallisation of Ag and Pt produced nanostructures with a highly anisotropic morphology, i.e., hierarchical nanofern structures, which provide high-density active sites on the catalyst surface for an efficient catalytic reaction. The extent of the effect of structural growth on the catalytic performance of hierarchical AgPt nanoferns is discussed.
Several studies have shown that the mammalian target of rapamycin (mTOR) inhibitor; everolimus (EV) improves patient survival in several types of cancer. However, the meaningful efficacy of EV as a single agent for the treatment of colorectal cancer (CRC) has failed to be proven in multiple clinical trials. Combination therapy is one of the options that could increase the efficacy and decrease the toxicity of the anticancer therapy. This study revealed that the β-cyclodextrin (β-CD):FGF7 complex has the potential to improve the antiproliferative effect of EV by preventing FGF receptor activation and by enhancing EV cellular uptake and intracellular retention. Molecular docking techniques were used to investigate the possible interaction between EV, β-CD, and FGF7. Molecular docking insights revealed that β-CD and EV are capable to form a stable inclusion complex with FGF at the molecular level. The aqueous solubility of the inclusion complex was increased (3.1 ± 0.23 μM) when compared to the aqueous solubility of pure EV (1.7 ± 0.16 μM). In addition, the in vitro cytotoxic activity of a FGF7:β-CD:EV complex on Caco-2 cell line was investigated using real-time xCELLigence technology. The FGF7:β-CD:EV complex has induced apoptosis of Caco-2 cells and shown higher cytotoxic activity than the parent drug EV. With the multitargets effect of β-CD:FGF7 and EV, the antiproliferative effect of EV was remarkably improved as the IC50 value of EV was reduced from 9.65 ± 1.42 to 1.87 ± 0.33 μM when compared to FGF7:β-CD:EV complex activity. In conclusion, the findings advance the understanding of the biological combinational effects of the β-CD:FGF7 complex and EV as an effective treatment to combat CRC.
Many studies have investigated natural convection heat transfer from the outside surface of horizontal and vertical cylinders in both constant heat flux and temperature conditions. However, there are poor studies in natural convection from inclined cylinders. In this study, free convection heat transfer was examined experimentally from the outside surface of a cylinder for glycerol and water at various heat fluxes. The tests were performed at 10 different inclination angles of the cylinder, namely, φ = 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°, measured from the horizon. Our results indicated that the average Nusselt number reduces with the growth in the inclination of the cylinder to the horizon at the same heat flux, and the average Nusselt number enhanced with the growth in heat flux at the same angle. Also, the average Nusselt number of water is greater than that of glycerol. A new experimental model for predicting the average Nusselt number is suggested, which has a satisfactory accuracy for experimental data.
The K2NiF6 catalytic effect on the NaAlH4 dehydrogenation properties was studied in this work. The desorption temperature was studied using temperature-programmed desorption and exhibited a lower onset hydrogen release after doped with different wt % of K2NiF6 (5, 10, 15 and 20 wt %). It was found that the NaAlH4 doped with 5 wt % K2NiF6 showed the optimal value that can reduce the onset desorption temperature of about 160 °C compared to 190 °C for the milled NaAlH4. The NaAlH4 + 5 wt % K2NiF6 sample showed faster desorption kinetics where 1.5 wt % of hydrogen was released in 30 min at 150 °C. In contrast, the milled NaAlH4 only released about 0.2 wt % within the same time and temperature. From the Kissinger analysis, the apparent activation energy was 114.7 kJ/mol for the milled NaAlH4 and 89.9 kJ/mol for the NaAlH4-doped 5 wt % K2NiF6, indicating that the addition of K2NiF6 reduced the activation energy for hydrogen desorption of NaAlH4. It is deduced that the new phases of AlNi, NaF, and KH that were formed in situ during the dehydrogenation process are the key factors for the improvement of dehydrogenation properties of NaAlH4.
This article demonstrates a novel nanoscale surface modification method to enhance the selectivity of porous poly(dimethylsiloxane) (PDMS) in removing oil from water. The surface modification method is simple and low cost by using sugar as a sacrificial template for temporal adhering of carbon nanotubes (CNT) before addition of PDMS prepolymer to encapsulate the CNT on its surface once polymerized. The PDMS-CNT demonstrated a tremendous increase in absorption capacity up to 3-fold compared to previously reported absorbents composed solely of PDMS. Besides showcasing excellent absorption capacity, the PDMS-CNT also shows a faster absorption rate (25 s) as compared to that of pure PDMS (40 s). The enhanced absorption rate is due to the incorporation of CNT, which roughens the surface of the polymer at the nanoscale and lowers the surface energy of porous PDMS while at the same time increasing the absorbent hydrophobicity and oleophilicity. This property makes the absorbent unique in absorbing only oil but repelling water at the same time. The PDMS-CNT is an excellent absorbent material with outstanding recyclability and selectivity for removing oil from water.
This paper reports the synthesis of two-dimensional, hierarchical, porous, and (001)-faceted metal (Ag, Zn, and Al)-doped TiO2 nanostructures (TNSs) and the study of their photocatalytic activity. Two-dimensional metal-doped TNSs were synthesized using the hydrolysis of ammonium hexafluorotitanate in the presence of hexamethylenetetramine and metal precursors. Typical morphology of metal-doped TNSs is a hierarchical nanosheet that is composed of randomly stacked nanocubes (dimensions of up to 5 μm and 200 nm in edge length and thickness, respectively) and has dominant (001) facets exposed. Raman analysis and X-ray photoelectron spectroscopy results indicated that the Ag doping, compared to Zn and Al, much improves the crystallinity degree and at the same time dramatically lowers the valence state binding energy of the TNS and provides an additional dopant oxidation state into the system for an enhanced electron-transfer process and surface reaction. These are assumed to enhance the photocatalytic of the TNS. In a model of photocatalytic reaction, that is, rhodamine B degradation, the AgTNS demonstrates a high photocatalytic activity by converting approximately 91% of rhodamine B within only 120 min, equivalent to a rate constant of 0.018 m-1 and ToN and ToF of 94 and 1.57 min-1, respectively, or 91.1 mmol mg-1 W-1 degradation when normalized to used light source intensity, which is approximately 2 times higher than the pristine TNS and several order higher when compared to Zn- and Al-doped TNSs. Improvement of the crystallinity degree, decrease in the defect density and the photogenerated electron and hole recombination, and increase of the oxygen vacancy in the AgTNS are found to be the key factors for the enhancement of the photocatalytic properties. This work provides a straightforward strategy for the preparation of high-energy (001) faceted, two-dimensional, hierarchical, and porous Ag-doped TNSs for potential use in photocatalysis and photoelectrochemical application.