| 1. |
- Abitbol, Tiffany, et al.
(author)
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Isolation of Mixed Compositions of Cellulose Nanocrystals, Microcrystalline Cellulose, and Lignin Nanoparticles from Wood Pulps
- 2023
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:24, s. 21474-21484
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Journal article (peer-reviewed)abstract
- From a circular economyperspective, one-pot strategies for theisolation of cellulose nanomaterials at a high yield and with multifunctionalproperties are attractive. Here, the effects of lignin content (bleachedvs unbleached softwood kraft pulp) and sulfuric acid concentrationon the properties of crystalline lignocellulose isolates and theirfilms are explored. Hydrolysis at 58 wt % sulfuric acid resulted inboth cellulose nanocrystals (CNCs) and microcrystalline celluloseat a relatively high yield (>55%), whereas hydrolysis at 64 wt% gaveCNCs at a lower yield (<20%). CNCs from 58 wt % hydrolysis weremore polydisperse and had a higher average aspect ratio (1.5-2x),a lower surface charge (2x), and a higher shear viscosity (100-1000x).Hydrolysis of unbleached pulp additionally yielded spherical nanoparticles(NPs) that were <50 nm in diameter and identified as lignin bynanoscale Fourier transform infrared spectroscopy and IR imaging.Chiral nematic self-organization was observed in films from CNCs isolatedat 64 wt % but not from the more heterogeneous CNC qualities producedat 58 wt %. All films degraded to some extent under simulated sunlighttrials, but these effects were less pronounced in lignin-NP-containingfilms, suggesting a protective feature, but the hemicellulose contentand CNC crystallinity may be implicated as well. Finally, heterogeneousCNC compositions obtained at a high yield and with improved resourceefficiency are suggested for specific nanocellulose uses, for instance,as thickeners or reinforcing fillers, representing a step toward thedevelopment of application-tailored CNC grades.
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| 2. |
- Al-Hinai, Muna H., et al.
(author)
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Antimicrobial Activity Enhancement of Poly(ether sulfone) Membranes by in Situ Growth of ZnO Nanorods
- 2017
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In: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 2:7, s. 3157-3167
-
Journal article (peer-reviewed)abstract
- Composite poly(ether sulfone) membranes integrated with ZnO nanostructures either directly blended or grown in situ have enhanced antibacterial activity with improved functionality in reducing the biofouling in water treatment applications. The pore structure and surface properties of the composite were studied to investigate the effect of the addition of ZnO nanostructures. The hydrophilicity of the blended membranes increased with a higher content of ZnO nanoparticles in the membrane (2-6%), which could be further controlled by varying the growth conditions of ZnO nanorods on the polymer surface. Improved water flux, bovine serum albumin rejection, and inhibition of Escherichia coli bacterial growth under visible light irradiation was observed for the membranes decorated with ZnO nanorods compared to those in the membranes simply blended with ZnO nanoparticles. No regrowth of E. coli was recorded even 2 days after the incubation.
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| 3. |
- Al-Jayyousi, Hiba, et al.
(author)
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Exploring the Superior Anchoring Performance of the Two-Dimensional Nanosheets B2C4P2 and B3C2P3 for Lithium-Sulfur Batteries
- 2022
-
In: ACS Omega. - : American Chemical Society. - 2470-1343. ; 7:43, s. 38543-38549
-
Journal article (peer-reviewed)abstract
- Potential anchoring materials in lithium–sulfur batteries help overcome the shuttle effect and achieve long-term cycling stability and high-rate efficiency. The present study investigates the two-dimensional nanosheets B2C4P2 and B3C2P3 by employing density functional theory calculations for their promise as anchoring materials. The nanosheets B2C4P2 and B3C2P3 bind polysulfides with adsorption energies in the range from −2.22 to −0.75 and −2.43 to −0.74 eV, respectively. A significant charge transfer occurs from the polysulfides, varying from −0.74 to −0.02e and −0.55 to −0.02e for B2C4P2 and B3C2P3, respectively. Upon anchoring the polysulfides, the band gap of B3C2P3 reduces, leading to enhanced electrical conductivity of the sulfur cathode. Finally, the calculated barrier energies of B2C4P2 and B3C2P3 for Li2S indicate fast diffusion of Li when recharged. These enthralling characteristics propose that the nanosheets B2C4P2 and B3C2P3 could reduce the shuttle effect in Li–S batteries and significantly improve their cycle performance, suggesting their promise as anchoring materials.
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| 4. |
- Al-Shammari, Rusul M., et al.
(author)
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Single-Molecule Nonresonant Wide-Field Surface-Enhanced Raman Scattering from Ferroelectrically Defined Au Nanoparticle Microarrays
- 2018
-
In: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 3:3, s. 3165-3172
-
Journal article (peer-reviewed)abstract
- Single-molecule detection by surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that is of interest for the sensor development field. An important aspect of optimizing the materials used in SERS-based sensors is the ability to have a high density of "hot spots" that enhance the SERS sensitivity to the single-molecule level. Photodeposition of gold (Au) nanoparticles through electric-field-directed self-assembly on a periodically proton-exchanged lithium niobate (PPELN) substrate provides conditions to form well-ordered microscale features consisting of closely packed Au nanoparticles. The resulting Au nanoparticle microstructure arrays (microarrays) are plasmon-active and support nonresonant single-molecule SERS at ultralow concentrations (<10(-9)-10(-13) M) with excitation power densities <1 x 10(-3) W cm(-2) using wide-field imaging. The microarrays offer excellent SERS reproducibility, with an intensity variation of <7.5% across the substrate. As most biomarkers and molecules do not support resonance enhancement, this work demonstrates that PPELN is a suitable template for high-sensitivity, nonresonant sensing applications.
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| 5. |
- Alimohammadzadeh, Rana, et al.
(author)
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Mild and Versatile Functionalization of Nacre-Mimetic Cellulose Nanofibrils/Clay Nanocomposites by Organocatalytic Surface Engineering
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:31, s. 19363-19370
-
Journal article (peer-reviewed)abstract
- Development of surface-engineering strategies, which are facile, versatile, and mild, are highly desirable in tailor-made functionalization of high-performance bioinspired nanocomposites. We herein disclose for the first time a general organocatalytic strategy for the functionalization and hydrophobization of nacre-mimetic nanocomposites, which includes vide supra key aspects of surface engineering. The merging of metal-free catalysis and the design of nacre-mimetic nanocomposite materials were demonstrated by the organocatalytic surface engineering of cellulose nanofibrils/clay nanocomposites providing the corresponding bioinspired nanocomposites with good mechanical properties, hydrophobicity, and useful thia-, amino, and olefinic functionalities.
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| 6. |
- Alvarado Ávila, María Isabel, et al.
(author)
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Cerium Oxide on a Fluorinated Carbon-Based Electrode as a Promising Catalyst for Hypochlorite Production
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:42, s. 37465-37475
-
Journal article (peer-reviewed)abstract
- Sodium hypochlorite (NaOCl) is widely used as a disinfectant agent for water treatment and surface cleaning. A straightforward way to produce NaOCl is by the electrolysis of an aqueous sodium chloride (NaCl) solution. This process presents several side reactions decreasing its efficiency with hypochlorite reduction on the cathode surface being one of the main detrimental reactions. In this work, we have studied carbon-based electrodes modified with cerium oxide (CeO2), fluorine, and platinum nanoparticles as cathodes for hypochlorite production. Fluorination was carried out electrochemically; the polyol method was used to synthesize platinum nanoparticles; and the hydrothermal process was applied to form a CeO2 layer. Scanning electron microscopy, FTIR, and inductively coupled plasma (ICP) indicated the presence of cerium oxide as a film, fluorine groups on the substrate, and a load of 3.2 mg/cm2 of platinum nanoparticles and 2.7 mg/cm2 of CeO2. From electrochemical impedance spectroscopy, it was possible to demonstrate that incorporating platinum and fluorine decreases the charge transfer resistance by 16% and 28%, respectively. Linear sweep voltammetry showed a significant decrease in hypochlorite reduction when the substrate was doped with fluorine from -16.6 mA/cm2 at -0.6 V to -9.64 mA/cm2 that further reduced to -8.78 mA/cm2 with cerium oxide covered fluorinated electrodes. The performance of the cathode materials during hypochlorite production improved by 80% compared with pristine activated carbon cloth (ACC) electrodes. The improvement toward hindering NaOCl reduction is probably caused by the incorporation of a partial negative charge upon doping with fluorine.
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| 7. |
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| 8. |
- Amjad, Muhammad Raiees, et al.
(author)
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Carbonate Reservoir Quality Variations in Basins with a Variable Sediment Influx: A Case Study from the Balkassar Oil Field, Potwar, Pakistan
- 2023
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:4, s. 4127-4145
-
Journal article (peer-reviewed)abstract
- The carbonate reservoir quality is strongly reliant on the compaction process during sediment burial and other processes such as cementation and dissolution. Porosity and pore pressure are the two main factors directly affected by mechanical and chemical compactions. Porosity reduction in these carbonates is critically dependent on the overburden stress and subsidence rate. A variable sediment influx in younger basins may lead to changes in the reservoir quality in response to increasing lithostatic pressure. Deposition of molasse sediments as a result of the Himalayan orogeny caused variations in the sedimentation influx in the Potwar Basin of Pakistan throughout the Neogene times. The basic idea of this study is to analyze the carbonate reservoir quality variations induced by the compaction and variable sediment influx. The Sakesar Limestone of the Eocene age, one of the proven carbonate reservoirs in the Potwar Basin, shows significant changes in the reservoir quality, specifically in terms of porosity and pressure. A 3D seismic cube (10 km2) and three wells of the Balkassar field are used for this analysis. To determine the vertical and lateral changes of porosity in the Balkassar area, porosity is computed from both the log and seismic data. The results of both the data sets indicate 2–4% porosities in the Sakesar Limestone. The porosity reduction rate with respect to the lithostatic pressure computed with the help of geohistory analysis represents a sharp decrease in porosity values during the Miocene times. Pore pressure predictions in the Balkassar OXY 01 well indicate underpressure conditions in the Sakesar Limestone. The Eocene limestones deposited before the collision of the Indian plate had enough time for fluid expulsion and show underpressure conditions with high porosities.
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| 9. |
- Andersson, Hanna, 1979, et al.
(author)
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Assessing the Ability of Spectroscopic Methods to Determine the Difference in the Folding Propensities of Highly Similar beta-Hairpins
- 2017
-
In: Acs Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:2, s. 508-516
-
Journal article (peer-reviewed)abstract
- We have evaluated the ability of nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopies to describe the difference in the folding propensities of two structurally highly similar cyclic beta-hairpins, comparing the outcome to that of molecular dynamics simulations. NAMFIS-type NMR ensemble analysis and CD spectroscopy were observed to accurately describe the consequence of altering a single interaction site, whereas a single-site C-13 NMR chemical shift melting curve-based technique was not.
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| 10. |
- Andersson, Hanna, Dr. 1979-, et al.
(author)
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Binding of 2-(Triazolylthio)acetamides to Metallo-beta-lactamase CcrA Determined with NMR
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:34, s. 21570-21578
-
Journal article (peer-reviewed)abstract
- Metallo-beta-lactamase (MBL)-producing bacteria resistant to beta-lactam antibiotics are a serious threat to human health. Despite great efforts and important progress in the discovery of MBL inhibitors (MBLIs), there is none in clinical use. Herein, inhibitor complexes of the MBL CcrA were investigated by NMR spectroscopy to provide perspectives on the further development of 2-(triazolylthio)acetamide-type MBLIs. By using the NMR-based chemical shift perturbation (CSP) and direction of CSP methodologies together with molecular docking, the spatial orientation of three compounds in the CcrA active site was investigated (4-6). Inhibitor 6 showed the best binding affinity (K-d approximate to 2.3 +/- 0.3 mu M), followed by 4 (K-d approximate to 11 +/- 11 mu M) and 5 (K-d = 34 +/- 43 mu M), as determined from the experimental NMR data. Based on the acquired knowledge, analogues of other MBLIs (1-3) were designed and evaluated in silico with the purpose of examining a strategy for promoting their interactions with the catalytic zinc ions.
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| 11. |
- Antonio, Capezza, et al.
(author)
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Preparation and Comparison of Reduced Graphene Oxide and Carbon Nanotubes as Fillers in Conductive Natural Rubber for Flexible Electronics
- 2019
-
In: Omega. - : American Chemical Society (ACS). - 0030-2228 .- 1541-3764. ; 4:2
-
Journal article (peer-reviewed)abstract
- Conductive natural rubber (NR) nanocomposites were prepared by solvent-casting suspensions of reduced graphene oxide(rGO) or carbon nanotubes (CNTs), followed by vulcanization of the rubber composites. Both rGO and CNT were compatible as fillers in the NR as well as having sufficient intrinsic electrical conductivity for functional applications. Physical (thermal) and chemical reduction of GO were investigated, and the results of the reductions were monitored by X-ray photoelectron spectroscopy for establishing a reduction protocol that was useful for the rGO nanocomposite preparation. Field-emission scanning electron microscopy showed that both nanofillers were adequately dispersed in the main NR phase. The CNT composite displays a marked mechanical hysteresis and higher elongation at break, in comparison to the rGO composites for an equal fraction of the carbon phase. Moreover, the composite conductivity was always ca. 3-4 orders of magnitude higher for the CNT composite than for the rGO composites, the former reaching a maximum conductivity of ca. 10.5 S/m, which was explained by the more favorable geometry of the CNT versus the rGO sheets. For low current density applications though, both composites achieved the necessary percolation and showed the electrical conductivity needed for being applied as flexible conductors for a light-emitting diode.
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| 12. |
- Anusuyadevi, Prasaanth Ravi, et al.
(author)
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Floating Photocatalysts for Effluent Refinement Based on Stable Pickering Cellulose Foams and Graphitic Carbon Nitride (g-C3N4)
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:35, s. 22411-22419
-
Journal article (peer-reviewed)abstract
- The transfer of heterogeneous photocatalysis applications from the laboratory to real-life aqueous systems is challenging due to the higher density of photocatalysts compared to water, light attenuation effects in water, complicated recovery protocols, and metal pollution from metal-based photocatalysts. In this work, we overcome these obstacles by developing a buoyant Pickering photocatalyst carrier based on green cellulose nanofibers (CNFs) derived from wood. The air bubbles in the carrier were stable because the particle surfactants provided thermodynamic stability and the derived photocatalytic foams floated on water throughout the test period (4 weeks). A metal-free semiconductor photocatalyst, g-C3N4, was facilely embedded inside the foam by mixing the photocatalyst with the air-bubble suspension followed by casting and drying to produce solid foams. When tested under mild irradiation conditions (visible light, low energy LEDs) and no agitation, almost three times more dye was removed after 6 h for the floating g-C3N4-CNF nanocomposite foam, compared to the pure g-C3N4 powder residing on the bottom of a ca. 2 cm-high water pillar. The buoyancy and physicochemical properties of the carrier material were imperative to render escalated oxygenation, high photon utilization, and faster dye degradation. The reported assembly protocol is facile, general, and provides a new strategy for assembling green floating foams that can potentially carry a number of different photocatalysts.
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| 13. |
- Aouelela, Marwa H. A., et al.
(author)
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Synthesis and Characterization of Molybdenum- and Sulfur-Doped FeSe
- 2023
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:39, s. 36553-36561
-
Journal article (peer-reviewed)abstract
- During the past decade, two-dimensional (2D) layered materials opened novel opportunities for the exploration of exciting new physics and devices owing to their physical and electronic properties. Among 2D materials, iron selenide has attracted much attention from several physicists as they provide a fruitful stage for developing new superconductors. Chemical doping offers a powerful approach to manipulate and optimize the electronic structure and physical properties of materials. Here, to reveal how doping affects the physical properties in FeSe, we report on complementary measurements of molybdenum- and sulfur-doped FeSe with theoretical calculations. Mo0.1Fe0.9Se0.9S0.1 was synthesized by a one-step solid-state reaction method. Crystal structure and morphology were studied using powder X-ray diffraction and scanning electron microscopy. Thermal stability and decomposition behavior in doped samples were studied by thermogravimetric analysis, and to understand the microscopic influence of doping, we performed Raman spectroscopy. First-principles calculations of the electronic structure illustrate distinct changes of electronic structures of the substituted FeSe systems, which can be responsible for their superconducting properties.
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| 14. |
- Arkell, Karolina, et al.
(author)
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Mechanistic Modeling of Reversed-Phase Chromatography of Insulins with Potassium Chloride and Ethanol as Mobile-Phase Modulators
- 2017
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2, s. 136-146
-
Journal article (peer-reviewed)abstract
- The purpose of this study was to investigate the adsorption mechanism in reversed-phase chromatography (RPC) of proteins and to develop a model for the effect of dual mobile phase modulators—a salt and an organic solvent—on this process. Two different adsorption mechanisms were considered: (1) pure association of a protein molecule and one or more ligands and (2) displacement of the organic modulator, with which the adsorbent is saturated, by the protein upon association with one or more ligands. One model was then derived from each of the two considered mechanisms, combining thermodynamic theories on salting-in, RPC, and the solubility of proteins. The model was then applied to chromatographic data from an earlier report as well as supplementary data for solubility and vapor–liquid equilibria, and case-specific simplifications were made. We found that an adaptation of Kirkwood’s electrostatic theories to hydrophobic interaction chromatography describes the observed effect of KCl well. Combining chromatographic and solubility data for one of the insulins, we concluded that the variation in the activity coefficient of the insulin with respect to the concentration of ethanol alone cannot describe its effect on retention. Consequently, one or more other phenomena must affect the adsorption process. Our second model fits the retention data well, supporting the hypothesis that ethanol is directly involved in the adsorption mechanism in this case. Using additional experiments at a high-protein load, we extended the linear-range equilibrium model into a dynamic model for preparative conditions. This model shows good agreement with the high-load data for one of the insulin variants, without any additional effects of the modulator concentrations on the adsorption capacity.
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| 15. |
- Arkell, Karolina, et al.
(author)
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Mechanistic Modeling of Reversed-Phase Chromatography of Insulins within the Temperature Range 10–40 °C
- 2018
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 3:2, s. 1946-1954
-
Journal article (peer-reviewed)abstract
- In the many published theories on the retention in reversed-phase chromatography (RPC), the focus is generally on the effect of the concentration of the mobile phase modulator(s), although temperature is known to have a significant influence both on the retention and on the selectivity between the adsorbates. The aim of this study was to investigate and model the combined effects of the temperature and the modulator concentrations on RPC of three insulin variants. KCl and ethanol were used as mobile phase modulators, and the experiments were performed on two different adsorbents, with C18 and C4 ligands. The temperature dependence was investigated for the interval 10–40 °C and at two different concentrations of each modulator. The model is derived from the expression for the adsorption equilibrium, which assumes that ethanol is adsorbed to the ligands and displaced by the insulin molecules, similar to the displacement of counterions in the steric mass-action model for ion-exchange chromatography. A good model fit to the new linear-range retention data was achieved by only adding and calibrating three parameters for the temperature dependence of the equilibrium. We found that a lower temperature results in a longer retention time for all adsorbates, adsorbents, and modulator concentrations used in this study, indicating that the adsorption process is enthalpy-driven. A comparison of the different contributions to the temperature dependence revealed that the large contribution from the equilibrium constant is dampened by the significant contributions of the opposite sign from the changes in activity coefficients of insulins and ethanol. Neglect of these effects when comparing different adsorbents and modulators might yield incorrect conclusions because the equilibrium constant varies with both, whereas the activity coefficients should be independent of the adsorbent. As expected, the conditions that promote higher retention also give a higher selectivity between the adsorbates. Nonetheless, in relation to its effect on the retention, the influence of the KCl concentration on the selectivity was significantly stronger than that of the temperature or that of the ethanol concentration.
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| 16. |
- Arkhipov, Victor P., et al.
(author)
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Micelles of Oxyethylated Isononylphenols in Aqueous Solutions and Hydrophilic–Lipophilic Balance
- 2020
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:43, s. 28224-28232
-
Journal article (peer-reviewed)abstract
- We have measured the self-diffusion coefficients and calculated the effective hydrodynamic radii of micelles of ethoxylated isononylphenols in aqueous solutions in the presence of sodium chloride, as well as in their binary mutual mixtures, when approaching cloudy conditions. These cloudy conditions were created by an increase in temperature, a change in the concentration of an electrolyte in the solution, or a mutual ratio of neonols in their binary mixtures. The results are discussed within the concept of the hydrophilic–lipophilic balance.
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| 17. |
- Arkhipov, Victor P., et al.
(author)
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Rhamnolipid Biosurfactant: Use for the Removal of Phenol from Aqueous Solutions by Micellar Solubilization
- 2023
-
In: ACS Omega. - : American Chemical Society. - 2470-1343. ; 8:33, s. 30646-30654
-
Journal article (peer-reviewed)abstract
- Selective measurements of the self-diffusion coefficients of molecules of the biological surfactant rhamnolipid (RL) in individual aqueous solutions and in solutions with phenol as a solubilizate were carried out by nuclear magnetic resonance (NMR) diffusometry. Based on the obtained results, the solubilization characteristics of RLs were calculated. They are the fraction of solubilized phenol molecules, the phenol micelle-water distribution coefficient, the molar solubilization coefficient, the hydrodynamic radii of RL monomers and micelles, the aggregation numbers of micelles, and the solubilization capacity of micelles. Fraction of the solubilized phenol molecules increases and approaches 80-90% with increasing RL concentration. The solubilization capacity of the micelles increases from several units to 102 with an increase in both the concentration of RLs and the concentration of phenol in solution.
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| 18. |
- Arora, Neha, et al.
(author)
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NMR-Based Metabolomic Approach To Elucidate the Differential Cellular Responses during Mitigation of Arsenic(III, V) in a Green Microalga
- 2018
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 3:9, s. 11847-11856
-
Journal article (peer-reviewed)abstract
- Nuclear magnetic resonance (NMR)-based metabolomic approach is a high-throughput fingerprinting technique that allows a rapid snapshot of metabolites without any prior knowledge of the organism. To demonstrate the applicability of NMR-based metabolomics in the field of microalgal-based bioremediation, novel freshwater microalga Scenedesmus sp. IITRIND2 that showed hypertolerance to As(III, V) was chosen for evaluating the metabolic perturbations during arsenic stress in both its oxidation states As(III) and As(V). Using NMR spectroscopy, we were able to identify and quantify an array of ∼45 metabolites, including amino acids, sugars, organic acids, phosphagens, osmolytes, nucleotides, etc. The NMR metabolomic experiments were complemented with various biophysical techniques to establish that the microalga tolerated the arsenic stress using a complex interplay of metabolites. The two different arsenic states distinctly influenced the microalgal cellular mechanisms due to their altered physicochemical properties. Eighteen differentially identified metabolites related to bioremediation of arsenic were then correlated to the major metabolic pathways to delineate the variable stress responses of microalga in the presence of As(III, V).
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| 19. |
- Arza, Carlos R., et al.
(author)
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Synthesis, Thermal Properties, and Rheological Characteristics of Indole-Based Aromatic Polyesters
- 2019
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:12, s. 15012-15021
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Journal article (peer-reviewed)abstract
- Currently, there is an intensive development of bio-based aromatic building blocks to replace fossil-based terephthalates used for poly(ethylene terephthalate) production. Indole is a ubiquitous aromatic unit in nature, which has great potential as a bio-based feedstock for polymers or plastics. In this study, we describe the synthesis and characterization of new indole-based dicarboxylate monomers with only aromatic ester bonds, which can improve the thermal stability and glass-transition temperature (Tg) of the resulting polyesters. The new dicarboxylate monomers were polymerized with five aliphatic diols to yield 10 new polyesters with tunable chemical structures and physical properties. Particularly, the Tg values of the obtained polyesters can be as high as 113 °C, as indicated by differential scanning calorimetry and dynamic mechanical analysis. The polyesters showed decent thermal stability and distinct flow transitions as revealed by thermogravimetric analysis and rheology measurements.
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| 20. |
- Asimi Neisiani, Ali, et al.
(author)
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Technical and Economic Comparison between Sodium and Ammonium Agents in the Jarosite Precipitation Process─An Evaluation for Industrial Applications
- 2023
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In: ACS Omega. - : American Chemical Society. - 2470-1343. ; 8:39, s. 35442-36613
-
Journal article (peer-reviewed)abstract
- Iron content can cause severe challenges through zinc production from zinc sulfide concentrate. The zinc industry extensively uses the jarosite precipitation process (JPP) to precipitate dissolved iron and remove it before transferring the solution to downstream stages. Precipitating agents (PAs) play an essential role in the JPP. However, surprisingly, no study compares the efficiency of various PAs on an industrial scale. As an innovative approach, this investigation compares the technical and economic aspects of using various sodium and ammonium compounds (hydroxides, carbonates, bicarbonates, sulfates, and bisulfates) as typical PAs for the JPP at the Bafgh Zinc Smelting Company (BZSC) plant. Experimental results revealed that ammonium hydroxide, with 90.85% iron removal efficiency, had the highest performance, and sodium bisulfate and ammonium bisulfate had the lowest efficiency (74.54 and 77.13%, respectively). However, since ammonium hydroxide is a corrosive PA, it is not a promising alternative to sodium sulfate (with both economic and safety issues). Based on technical and economic assessments, sodium carbonate (84.31% iron removal efficiency) showed the highest potential for an efficient JPP.
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| 21. |
- Atif, Abdul-Raouf, 1996-, et al.
(author)
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Experimental Characterization and Mathematical Modeling of the Adsorption of Proteins and Cells on Biomimetic Hydroxyapatite
- 2022
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:1, s. 908-920
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Journal article (peer-reviewed)abstract
- Biomaterial development is a long process consisting of multiple stages of design and evaluation within the context of both in vitro and in vivo testing. To streamline this process, mathematical and computational modeling displays potential as a tool for rapid biomaterial characterization, enabling the prediction of optimal physicochemical parameters. In this work, a Langmuir isotherm-based model was used to describe protein and cell adhesion on a biomimetic hydroxyapatite surface, both independently and in a one-way coupled system. The results indicated that increased protein surface coverage leads to improved cell adhesion and spread, with maximal protein coverage occurring within 48 h. In addition, the Langmuir model displayed a good fit with the experimental data. Overall, computational modeling is an exciting avenue that may lead to savings in terms of time and cost during the biomaterial development process.
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| 22. |
- Aung, Su Htike, et al.
(author)
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2-(4-Butoxyphenyl)-N-hydroxyacetamide : An Efficient Preadsorber for Dye-Sensitized Solar Cells
- 2017
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:5, s. 1820-1825
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Journal article (peer-reviewed)abstract
- The effect of chemical modification of mesoporous TiO2 electrodes by 2-(4-butoxyphenyl)-N-hydroxyacetamide (BPHA) before dye adsorption is investigated in dye-sensitized solar cells (DSCs). Two organic dyes, LEG4 and Dyenamo blue, were used in combination with the cobalt (II/III) tris(bipyridine) redox couple. The photovoltaic performance of the DSCs is clearly enhanced by BPHA. Preadsorption of mesoporous TiO2 electrodes with BPHA lowered the amount of adsorbed dye but improved the shortcircuit current densities and the power conversion efficiencies by 10-20%, while keeping the open-circuit potential essentially unaffected. Notably, BPHA improved the LEG4 performance, whereas it has been reported for this dye that chenodeoxycholic acid as a coadsorbent lowers solar cell efficiency. Faster dye regeneration was found to be one reason for improved performance, but improved electron injection efficiency may also contribute to the favorable effect of BPHA.
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| 23. |
- Aziz, Anam, et al.
(author)
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Preparation and Evaluation of a Self-Emulsifying Drug Delivery System for Improving the Solubility and Permeability of Ticagrelor
- 2024
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 9:9, s. 10522-10538
-
Journal article (peer-reviewed)abstract
- Ticagrelor (TCG) is a BCS class IV antiplatelet drug used to prevent platelet aggregation in patients with acute coronary syndrome, having poor solubility and permeability. The goal of this study was to develop a self-nanoemulsifying drug delivery system (SNEDDS) of TCG to improve its solubility and permeability. The excipients were selected based on the maximum solubility of TCG and observed by UV spectrophotometer. Different combinations of oil, surfactant, and co-surfactant (1:1, 2:1, and 3:1) were used to prepare TCG-SNEDDS formulations, and pseudo-ternary phase diagrams were plotted. The nanoemulsion region was observed. Clove oil (10–20%), Tween-80 (45–70%), and PEG-400 (20–45%) were used as an oil, surfactant, and co-surfactant, respectively. The selected formulations (F1, F2, F3, F4, F5, and F6) were analyzed for ζ potential, polydispersity index (PDI), ζ size, self-emulsification test, cloud point determination, thermodynamic studies, entrapment efficiency, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), in vitro dissolution, ex vivo permeation, and pharmacodynamic study. The TCG-SNEDDS formulations exhibited ζ potential from −9.92 to −6.23 mV, a ζ average of 11.85–260.4 nm, and good PDI. The in vitro drug release in phosphate buffer pH 6.8 from selected TCG-SNEDDS F4 was about 98.45%, and F6 was about 97.86%, displaying improved dissolution of TCG in 0.1 N HCl and phosphate buffer pH 6.8, in comparison to 28.05% of pure TCG suspension after 12 h. While the in vitro drug release in 0.1 N HCl from F4 was about 62.03%, F6 was about 73.57%, which is higher than 10.35% of the pure TCG suspension. In ex vivo permeability studies, F4 also exhibited an improved apparent permeability of 2.7 × 10–6 versus 0.6708 × 10–6 cm2/s of pure drug suspension. The pharmacodynamic study in rabbits demonstrated enhanced antiplatelet activity from TCG-SNEDDS F4 compared to that from pure TCG suspension. These outcomes imply that the TCG-SNEDDS may serve as an effective means of enhancing TCG’s antiplatelet activity by improving the solubility and permeability of TCG.
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| 24. |
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| 25. |
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| 26. |
- Bashardanesh, Zahedeh, et al.
(author)
-
Rotational and Translational Diffusion of Proteins as a Function of Concentration
- 2019
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:24, s. 20654-20664
-
Journal article (peer-reviewed)abstract
- Atomistic simulations of three different proteins at different concentrations are performed to obtain insight into protein mobility as a function of protein concentration. We report on simulations of proteins from diluted to the physiological water concentration (about 70% of the mass). First, the viscosity was computed and found to increase by a factor of 7-9 going from pure water to the highest protein concentration, in excellent agreement with in vivo nuclear magnetic resonance results. At a physiological concentration of proteins, the translational diffusion is found to be slowed down to about 30% of the in vitro values. The slow-down of diffusion found here using atomistic models is slightly more than that of a hard sphere model that neglects the electrostatic interactions. Interestingly, rotational diffusion of proteins is slowed down somewhat more (by about 80-95% compared to in vitro values) than translational diffusion, in line with experimental findings and consistent with the increased viscosity. The finding that rotation is retarded more than translation is attributed to solvent-separated clustering. No direct interactions between the proteins are found, and the clustering can likely be attributed to dispersion interactions that are stronger between proteins than between protein and water. Based on these simulations, we can also conclude that the internal dynamics of the proteins in our study are affected only marginally under crowding conditions, and the proteins become somewhat more stable at higher concentrations. Simulations were performed using a force field that was tuned for dealing with crowding conditions by strengthening the protein-water interactions. This force field seems to lead to a reproducible partial unfolding of an alpha-helix in one of the proteins, an effect that was not observed in the unmodified force field.
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| 27. |
- Bayani, Amirhossein, et al.
(author)
-
Intercalation of Au Atoms into SiC(0001)/Buffer Interfaces : A First-Principles Density Functional Theory Study
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:24, s. 14842-14846
-
Journal article (peer-reviewed)abstract
- The process of Au intercalation into a SiC/buffer interface has been theoretically investigated here by using density functional theory (DFT) and the nudged elastic band (NEB) method. Energy barriers were at first calculated (using NEB) for the transfer of an Au atom through a free-standing graphene sheet. The graphene sheet was either of a nondefect character or with a defect in the form of an enlarged hexagonal carbon ring. Defects in the form of single and double vacancies were also considered. Besides giving a qualitative prediction of the relative energy barriers for the corresponding SiC/buffer interfaces, some of the graphene calculations also proved evidence of energy minima close to the graphene sheet. The most stable Au positions within the SiC/buffer interface were, therefore, calculated by performing geometry optimization with Au in the vicinity of the buffer layer. Based on these NEB and DFT calculations, two factors were observed to have a great influence on the Au intercalation process: (i) energy barrier and (ii) preferential bonding of Au to the radical C atoms at the edges of the vacancies. The energy barriers were considerably smaller in the presence of vacancies. However, the Au atoms preferred to bind to the edge atoms of these vacancies when approaching the buffer layer. It can thereby be concluded that the Au intercalation will only occur for a nondefect buffer layer when using high temperature and/or by using high-energy impacts by Au atoms. For this type of Au intercalation, the buffer layer will become completely detached from the SiC surface, forming a single layer of graphene with an intact Dirac point.
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| 28. |
- Behroozi Kohlan, Taha, et al.
(author)
-
Amphiphilic Polyoxazoline Copolymer-Imidazole Complexes as Tailorable Thermal Latent Curing Agents for One-Component Epoxy Resins
- 2023
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:49, s. 47173-47186
-
Journal article (peer-reviewed)abstract
- One-component epoxy resins (OCERs) are proposed to overcome the energy inefficiency and processing difficulties of conventional two-component epoxy resins by employing latent curing agents, specifically thermal latent curing agents (TLCs). Despite recent progress, the need for TLCs with a simple preparation method for different curing agents, epoxy resins, and process conditions remains. Here, tailorable TLCs were prepared by forming complexes between imidazole (Im) and amphiphilic polyoxazoline copolymers with tunable structures and properties by a solvent evaporation method. The obtained TLCs were manually mixed with DGEBA to prepare OCERs. The miscibility of the complexes with DGEBA was studied, considering the functionalities of copolymers. The curing behaviors of TLCs were compared using dynamic Differential Scanning Calorimetry (DSC) studies considering the side chain and composition of the copolymers, copolymer:Im ratio, and concentration of Im in DGEBA. The curing behavior of the promising OCERs was studied by isothermal DSC studies to investigate their stability at different temperatures and curing rate at elevated temperatures revealing the stability of these OCERs.
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| 29. |
- Bengtsson, Andreas, et al.
(author)
-
Continuous Stabilization and Carbonization of a Lignin–Cellulose Precursor to Carbon Fiber
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:19, s. 16793-16802
-
Journal article (peer-reviewed)abstract
- : The demand for carbon fibers (CFs) based onrenewable raw materials as the reinforcing fiber in composites forlightweight applications is growing. Lignin−cellulose precursorfibers (PFs) are a promising alternative, but so far, there is limitedknowledge of how to continuously convert these PFs underindustrial-like conditions into CFs. Continuous conversion is vitalfor the industrial production of CFs. In this work, we havecompared the continuous conversion of lignin−cellulose PFs (50wt % softwood kraft lignin and 50 wt % dissolving-grade kraft pulp)with batchwise conversion. The PFs were successfully stabilizedand carbonized continuously over a total time of 1.0−1.5 h,comparable to the industrial production of CFs from polyacrylonitrile. CFs derived continuously at 1000 °C with a relative stretch of−10% (fiber contraction) had a conversion yield of 29 wt %, a diameter of 12−15 μm, a Young’s modulus of 46−51 GPa, and atensile strength of 710−920 MPa. In comparison, CFs obtained at 1000 °C via batchwise conversion (12−15 μm diameter) with arelative stretch of 0% and a conversion time of 7 h (due to the low heating and cooling rates) had a higher conversion yield of 34 wt%, a higher Young’s modulus (63−67 GPa) but a similar tensile strength (800−920 MPa). This suggests that the Young’s moduluscan be improved by the optimization of the fiber tension, residence time, and temperature profile during continuous conversion,while a higher tensile strength can be achieved by reducing the fiber diameter as it minimizes the risk of critical defects.
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| 30. |
- Berntsson, Elina, et al.
(author)
-
Mercury Ion Binding to Apolipoprotein E Variants ApoE2, ApoE3, and ApoE4 : Similar Binding Affinities but Different Structure Induction Effects
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:33, s. 28924-28931
-
Journal article (peer-reviewed)abstract
- Mercury intoxication typically produces more severe outcomes in people with the APOE-ε4 gene, which codes for the ApoE4 variant of apolipoprotein E, compared to individuals with the APOE-ε2 and APOE-ε3 genes. Why the APOE-ε4 allele is a risk factor in mercury exposure remains unknown. One proposed possibility is that the ApoE protein could be involved in clearing of heavy metals, where the ApoE4 protein might perform this task worse than the ApoE2 and ApoE3 variants. Here, we used fluorescence and circular dichroism spectroscopies to characterize the in vitro interactions of the three different ApoE variants with Hg(I) and Hg(II) ions. Hg(I) ions displayed weak binding to all ApoE variants and induced virtually no structural changes. Thus, Hg(I) ions appear to have no biologically relevant interactions with the ApoE protein. Hg(II) ions displayed stronger and very similar binding affinities for all three ApoE isoforms, with KD values of 4.6 μM for ApoE2, 4.9 μM for ApoE3, and 4.3 μM for ApoE4. Binding of Hg(II) ions also induced changes in ApoE superhelicity, that is, altered coil–coil interactions, which might modify the protein function. As these structural changes were most pronounced in the ApoE4 protein, they could be related to the APOE-ε4 gene being a risk factor in mercury toxicity.
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| 31. |
- Bhagavathiachari, Muthuraaman, et al.
(author)
-
Polymer-doped molten salt mixtures as a new concept for electrolyte systems in dye-sensitized solar cells
- 2017
-
In: ACS Omega. - : American Chemical Society. - 2470-1343. ; 2:10, s. 6570-6575
-
Journal article (peer-reviewed)abstract
- A conceptually new polymer electrolyte for dye-sensitized solar cells is reported and investigated. The benefits of using this type of electrolyte based on ionic liquid mixtures (ILMs) and room temperature ionic liquids are highlighted. Impedance spectroscopy and transient electron measurements have been used to elucidate the background of the photovoltaic performance. Even though larger recombination losses were noted, the high ion mobility and conductivity induced in the ILMs by the added polymer result in enhanced overall conversion efficiencies.
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| 32. |
- Billinger, Erika, et al.
(author)
-
Characterization of Serine Protease Inhibitor from Solanum tuberosum Conjugated to Soluble Dextran and Particle Carriers
- 2019
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:19, s. 18456-18464
-
Research review (peer-reviewed)abstract
- A serine protease inhibitor was extracted from potato tubers. The inhibitor was conjugated to soluble, prefractionated dextran and titanium dioxide and zinc oxide nanoparticles. Conjugation to dextran was achieved by periodate oxidation of the dextran, followed by Schiff base coupling to inhibitor amino groups, and finally reduction, whereas the conjugation to the oxide particles was carried out by aminosilanization and carbonyldiimidazole activation. The inhibitory effect of the conjugated inhibitor was compared to that of free inhibitor in solution and with gelatin gel as a direct substrate. A certain degree of inhibitory activity was retained for both the dextran-conjugated and particle-conjugated inhibitors. In particular, the apparent Ki value of the dextran-conjugated inhibitor was found to be in the same range as that for free inhibitor. The dextran conjugate retained a higher activity than the free inhibitor after 1 month of storage at room temperature.
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| 33. |
- Bin, Li, et al.
(author)
-
Self-Assembly of Miktoarm Star Polyelectrolytes in Solutions with Various Ionic Strengths
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:24, s. 20791-20799
-
Journal article (peer-reviewed)abstract
- We studied the self-assembly of miktoarm star polyelectrolytes with different numbers of arms in solutions with various ionic strengths using coarse-grained molecular dynamic simulations. Spherical micelles are obtained for star polyelectrolytes with fewer arms, whereas wormlike clusters are obtained for star polyelectrolytes with more arms at a low ionic strength environment, with hydrophilic arms showing a stretched conformation. The number of clusters shows an overall decreasing tendency with increasing the number of arms in star polyelectrolytes due to strong electrostatic coupling between polycations and polyanions. The formation of wormlike clusters follows an overall stepwise pathway with an intermittent association–dissociation process for star polyelectrolytes with weak electrostatic coupling. These computational results can provide relevant physical insights to understand the self-assembly mechanism of star polyelectrolytes in solvents with various ionic strengths and to design star polyelectrolytes with functional groups that can fine-tune self-assembled structures for specific applications.
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| 34. |
- Björk, Emma
(author)
-
Surface Area Determination of Particle-Based Mesoporous Films Using Krypton Physisorption
- 2024
-
In: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 9:5, s. 5899-5902
-
Journal article (peer-reviewed)abstract
- One of the key characteristics of mesoporous films, making them attractive in many applications, is the surface enhancement gained by the porosity. Today, this attribute is rarely presented for particle-based mesoporous films. This work shows that krypton physisorption can be used to determine the available surface area of particle-based silica films synthesized by the direct growth (DiG) method. The surface area per substrate area of the films was measured to be 50-170 m(2)/m(2) and the surface area per film volume was 310-490 m(2)/cm(3) when the film thickness was varied between 100 and 520 nm. For comparison, a 105 nm thick film synthesized using dip-coating was used, as this technique renders more smooth films. The corresponding values for the dip-coated film was 90 m(2)/m(2) and 880 m(2)/cm(3), showing a higher surface area per film volume for the continuous film. The method is hence suitable for the characterization of mesoporous films synthesized with various techniques and can be used for the optimization of catalysts, drug delivery systems, and sensors.
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| 35. |
- Björnerbäck, Fredrik, et al.
(author)
-
Microporous Humins Synthesized in Concentrated Sulfuric Acid Using 5-Hydroxymethyl Furfural
- 2018
-
In: ACS OMEGA. - : American Chemical Society (ACS). - 2470-1343. ; 3:8, s. 8537-8545
-
Journal article (peer-reviewed)abstract
- A new class of highly porous organic sorbents called microporous humins is presented. These microporous humins are derived from sustainable and industrially abundant resources, have high heat of CO2 sorption, and could potentially be useful for the separation of carbon dioxide from gas mixtures. Their synthesis involves the polymerization of 5-hydroxymethyl furfural (HMF) in concentrated sulfuric acid and treatment with diethyl ether and heat. In particular, the porosities were tuned by the heat treatment. HMF is a potential platform chemical from biorefineries and a common intermediate in carbohydrate chemistry. A high uptake of CO2 (up to 5.27 mmol/g at 0 degrees C and 1 bar) and high CO2-over-N-2 and CO2-over-CH4 selectivities were observed. The microporous humins were aromatic and structurally amorphous, which was shown in a multipronged approach using C-13 nuclear magnetic resonance and Fourier transform infrared spectroscopies, elemental analysis, and wide-angle X-ray scattering.
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| 36. |
- Boberg, Mikael, et al.
(author)
-
Chiral Chromatographic Isolation on Milligram Scale of the Human African Trypanosomiasis Treatment D- and L-Eflornithine.
- 2020
-
In: ACS omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:37, s. 23885-23891
-
Journal article (peer-reviewed)abstract
- Eflornithine is a recommended treatment against the otherwise fatal parasitic disease late stage human African trypanosomiasis (HAT), also known as Gambian sleeping sickness. It is administered repeatedly as a racemic mixture intravenously (IV) together with oral nifurtimox. Racemic eflornithine has been investigated in clinical trials for oral dosing. However, due to low systemic exposures at a maximum tolerated oral dose, the drug is continued to be administered IV. The eflornithine enantiomers, D- and L-eflornithine, have different affinities to the target enzyme ornithine decarboxylase, suggesting that the pharmacodynamics of the enantiomers may differ. The aim of this study was to develop a method for isolation of d- and l-eflornithine from a racemic mixture. Several chiral stationary phases (CSPs) were evaluated for enantioselectivity using supercritical fluid chromatography (SFC) or high-performance liquid chromatography (HPLC). None of the tested CSPs rendered separation of the enantiomers in SFC mode. Separation of the enantiomers with SFC on the CSP Chiralpak IG was only achieved on an analytical scale after derivatization with ortho-phthalaldehyde (OPA). This was the first reported enantioselective SFC method for an eflornithine derivate. However, due to poor stability, the eflornithine-OPA derivates degraded and no chemically pure enantiomers were obtained. The CSP that showed enantioselectivity in HPLC mode was Chirobiotic R, which resulted in a successful isolation on a semipreparative milligram scale. The isolated eflornithine enantiomers will be tested in nonclinical in vitro and in vivo studies to support and assess the feasibility of a future clinical program with an oral HAT treatment.
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| 37. |
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| 38. |
- Botella, Pablo, et al.
(author)
-
Investigation on the Luminescence Properties of InMO4 (M = V5+, Nb5+, Ta5+) Crystals Doped with Tb3+ or Yb3+ Rare Earth Ions
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:5, s. 2148-2158
-
Journal article (peer-reviewed)abstract
- We explore the potential of Tb- and Yb-doped InVO4, InTaO4, and InNbO4 for applications as phosphors for light-emitting sources. Doping below 0.2% barely change the crystal structure and Raman spectrum but provide optical excitation and emission properties in the visible and near-infrared (NIR) spectral regions. From optical measurements, the energy of the first/second direct band gaps was determined to be 3.7/4.1 eV in InVO4, 4.7/5.3 in InNbO4, and 5.6/6.1 eV in InTaO4. In the last two cases, these band gaps are larger than the fundamental band gap (being indirect gap materials), while for InVO4, a direct band gap semiconductor, the fundamental band gap is at 3.7 eV. As a consequence, this material shows a strong self-activated photoluminescence centered at 2.2 eV. The other two materials have a weak self-activated signal at 2.2 and 2.9 eV. We provide an explanation for the origin of these signals taking into account the analysis of the polyhedral coordination around the pentavalent cations (V, Nb, and Ta). Finally, the characteristic green (5D4 → 7FJ) and NIR (2F5/2 → 2F7/2) emissions of Tb3+ and Yb3+ have been analyzed and explained.
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| 39. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(author)
-
Mechanical and Thermal Properties of Mixed PE Fractions from Post-Consumer Plastic Packaging Waste
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:49, s. 45181-45188
-
Journal article (peer-reviewed)abstract
- The functional properties of recycled post-consumer flexible polyethylene packaging waste have been studied using materials collected and sorted at a large-scale facility in Sweden. The studied fraction was used both as received and after simple laboratory washing in water with added sodium hydroxide at 40 °C. The materials were melt-compounded with a twin-screw extruder using two different temperature profiles and two screw configurations and injection-molded into slabs, whose thermal and mechanical properties were assessed. The results showed that the mechanical properties of injection-molded samples were not changed significantly either by the washing or by the temperature or screw configuration used in the compounding. Washing reduced the viscosity and molecular mass to a minor extent. As expected, the ash content of the compounded pellets was reduced by washing. The thermo-oxidative stability decreased with increasing compounding temperature and with washing.
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| 40. |
- Bu, Xiangning, et al.
(author)
-
Exploring the Relationships between Gas Dispersion Parameters and Differential Pressure Fluctuations in a Column Flotation
- 2021
-
In: ACS Omega. - : Elsevier. - 2470-1343. ; 6:34, s. 21900-21908
-
Journal article (peer-reviewed)abstract
- Flotation separation, which is the most important mineral beneficiation technique, is dependent on gas dispersion (hydrodynamic conditions). Thus, many investigations have focused on the precise determination of hydrodynamic conditions such as Reynolds number of the bubbles, bubble velocity, and bubble diameter. However, few studies have examined their relationships with pressure fluctuations in a column flotation. This study introduced the differential pressure fluctuations as an actual variable that could be considered to determine the collection zone’s hydrodynamic conditions in a cyclonic microbubble flotation column. In general, the outcomes indicated that superficial gas velocity had the most substantial relationship with the differential pressure fluctuations among other flotation factors (such as pump speed, superficial gas velocity, superficial water velocity, and frother dosage). Furthermore, a high coefficient of determination (R2 > 0.77) for the equation generated to assess the relationships demonstrated that differential pressure fluctuations could be used as a promising tool to determine the hydrodynamic parameters’ characteristics in the flotation columns.
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| 41. |
- Budnyak, Tetyana M., et al.
(author)
-
Electrostatic Deposition of the Oxidized Kraft Lignin onto the Surface of Aminosilicas : Thermal and Structural Characteristics of Hybrid Materials
- 2019
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:27, s. 22530-22539
-
Journal article (peer-reviewed)abstract
- In recent years, functional polymeric compounds have been widely used to modify the silica surface, which allows one to obtain the corresponding organomineral composites for broad application prospects. In this case, lignin-a cross-linked polyphenolic macromolecule-is of great interest according to its valuable properties and possible surplus as a by-product of pulp and paper industry and various biorefinery processes. Hybrid materials based on kraft softwood lignin and silica were obtained via the electrostatic attraction of oxidized lignin to the aminosilica surface with different porosities, which were prepared by the amination of the commercial silica gel with an average pore diameter of 6 nm, and the silica prepared in the lab with the oxidized kraft lignin and lignin-silica samples with an average pore diameter of 38 nm was investigated by physicochemical methods: two-dimensional nuclear magnetic resonance (NMR), P-31 NMR, Fourier transform infrared spectroscopy, thermogravimetric analysis in nitrogen and air atmosphere, scanning electron microscopy, and adsorption methods. After oxidation, the content of carboxylic groups almost doubled in the oxidized lignin, compared to that in the native one (0.74 mmol/g against 0.44 mmol/g, respectively). The lignin content was deposited onto the surface of aminosilica, depending on the porosity of the silica material and on the content of amino groups on its surface, giving lignin-aminosilica with 20% higher lignin content than the lignin-aminosilica gel. Both types of lignin-silica composites demonstrate a high sorptive capacity toward crystal violet dye. The suggested approach is an easy and low-cost way of synthesis of lignin-silica composites with unique properties. Such composites have a great potential for use as adsorbents in wastewater treatment processes.
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| 42. |
- Budnyak, Tetyana M., et al.
(author)
-
Membrane-Filtered Kraft Lignin-Silica Hybrids as Bio-Based Sorbents for Cobalt(II) Ion Recycling
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:19, s. 10847-10856
-
Journal article (peer-reviewed)abstract
- Efficient and sustainable recycling of cobalt(II) is of increasing importance to support technological development in energy storage and electric vehicle industries. A composite material based on membrane-filtered lignin deposited on nanoporous silica microparticles was found to be an effective and sustainable sorbent for cobalt(II) removal. This bio-based sorbent exhibited a high sorption capacity, fast kinetics toward cobalt(II) adsorption, and good reusability. The adsorption capacity was 18 mg Co(II) per gram of dry adsorbent at room temperature (22 degrees C) at near-neutral pH, three times higher than that of the summarized capacity of lignin or silica starting materials. The kinetics study showed that 90 min is sufficient for effective cobalt(II) extraction by the composite sorbent. The pseudo-second-order kinetics and Freundlich isotherm models fitted well with experimentally obtained data and confirmed heterogeneity of adsorption sites. The promising potential of the lignin-silica composites for industrial applications in the cobalt recovering process was confirmed by high values of desorption in mildly acidic solutions.
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| 43. |
- Busch, Michael, et al.
(author)
-
How to Predict the p Ka of Any Compound in Any Solvent
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:20, s. 17369-17383
-
Journal article (peer-reviewed)abstract
- Acid-base properties of molecules in nonaqueous solvents are of critical importance for almost all areas of chemistry. Despite this very high relevance, our knowledge is still mostly limited to the pKa of rather few compounds in the most common solvents, and a simple yet truly general computational procedure to predict pKa's of any compound in any solvent is still missing. In this contribution, we describe such a procedure. Our method requires only the experimental pKa of a reference compound in water and a few standard quantum-chemical calculations. This method is tested through computing the proton solvation energy in 39 solvents and by comparing the pKa of 142 simple compounds in 12 solvents. Our computations indicate that the method to compute the proton solvation energy is robust with respect to the detailed computational setup and the construction of the solvation model. The unscaled pKa's computed using an implicit solvation model on the other hand differ significantly from the experimental data. These differences are partly associated with the poor quality of the experimental data and the well-known shortcomings of implicit solvation models. General linear scaling relationships to correct this error are suggested for protic and aprotic media. Using these relationships, the deviations between experiment and computations drop to a level comparable to that observed in water, which highlights the efficiency of our method.
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| 44. |
- Cailotto, Simone, et al.
(author)
-
N-Doped Carbon Dot Hydrogels from Brewing Waste for Photocatalytic Wastewater Treatment
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:5, s. 4052-4061
-
Journal article (peer-reviewed)abstract
- The brewery industry annually produces huge amounts of byproducts that represent an underutilized, yet valuable, source of biobased compounds. In this contribution, the two major beer wastes, that is, spent grains and spent yeasts, have been transformed into carbon dots (CDs) by a simple, scalable, and ecofriendly hydrothermal approach. The prepared CDs have been characterized from the chemical, morphological, and optical points of view, highlighting a high level of N-doping, because of the chemical composition of the starting material rich in proteins, photoluminescence emission centered at 420 nm, and lifetime in the range of 5.5–7.5 ns. With the aim of producing a reusable catalytic system for wastewater treatment, CDs have been entrapped into a polyvinyl alcohol matrix and tested for their dye removal ability. The results demonstrate that methylene blue can be efficiently adsorbed from water solutions into the composite hydrogel and subsequently fully degraded by UV irradiation.
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| 45. |
- Calixto, Ana Rita, et al.
(author)
-
Recent Advances in Understanding Biological GTP Hydrolysis through Molecular Simulation
- 2020
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:9, s. 4380-4385
-
Research review (peer-reviewed)abstract
- GTP hydrolysis is central to biology, being involved in regulating a wide range of cellular processes. However, the mechanisms by which GTPases hydrolyze this critical reaction remain controversial, with multiple mechanistic possibilities having been proposed based on analysis of experimental and computational data. In this mini-review, we discuss advances in our understanding of biological GTP hydrolysis based on recent computational studies and argue in favor of solvent-assisted hydrolysis as a conserved mechanism among GTPases. A concrete understanding of the fundamental mechanisms by which these enzymes facilitate GTP hydrolysis will have significant impact both for drug discovery efforts and for unraveling the role of oncogenic mutations.
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| 46. |
- Capezza, Antonio Jose, et al.
(author)
-
Biodegradable Fiber-Reinforced Gluten Biocomposites for Replacement of Fossil-Based Plastics
- 2023
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 9:1, s. 1341-1351
-
Journal article (peer-reviewed)abstract
- Biocomposites based on wheat gluten and reinforced with carbon fibers were produced in line with the strive to replace fossil-based plastics with microplastic-free alternatives with competing mechanical properties. The materials were first extruded/compounded and then successfully injection molded, making the setup adequate for the current industrial processing of composite plastics. Furthermore, the materials were manufactured at very low extrusion and injection temperatures (70 and 140 degrees C, respectively), saving energy compared to the compounding of commodity plastics. The sole addition of 10 vol % fibers increased yield strength and stiffness by a factor of 2-4 with good adhesion to the protein. The biocomposites were also shown to be biodegradable, lixiviating into innocuous molecules for nature, which is the next step in the development of sustainable bioplastics. The results show that an industrial protein coproduct reinforced with strong fibers can be processed using common plastic processing techniques. The enhanced mechanical performance of the reinforced protein-based matrix herein also contributes to research addressing the production of safe materials with properties matching those of traditional fossil-based plastics.
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| 47. |
- Capezza, Antonio Jose, et al.
(author)
-
Superabsorbent and Fully Biobased Protein Foams with a Natural Cross-Linker and Cellulose Nanofibers
- 2019
-
In: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 4:19, s. 18257-18267
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Journal article (peer-reviewed)abstract
- The development of fully natural wheat gluten foams showing rapid and high uptake of water, sheep blood, and saline solution, while maintaining high mechanical stability in the swollen state, is presented. Genipin was added as a natural and polar cross-linker to increase the polarity of the protein chains, whereas cellulose nanofibers (CNFs) were added as a reinforcement/stiffener of the foams, alone or in combination with the genipin. The presence of only genipin resulted in a foam that absorbed up to 25 g of water per gram of foam and a more than 15 g uptake in only 8 min. In contrast, with CNF alone, it was not possible to maintain the mechanical stability of the foam during the water uptake and the protein foam disintegrated. The combination of CNF and genipin yielded a material with the best mechanical stability of the tested samples. In the latter case, the foam could be compressed repeatedly more than 80% without displaying any structural damage. The results revealed that a strong network had formed between the wheat gluten matrix, genipin, and cellulose in the foam structure. A unique feature of the absorbent/foam, in contrast to commercial superabsorbents, was that it was able to rapidly absorb nonpolar liquids (here, n-heptane) due to the open-cell structure. The capillary-driven absorption due to the open-cell structure, the high liquid absorption in the cell walls, and the mechanical properties (both in dry and swollen states) of these natural foams make them interesting as a sustainable replacement for a range of petroleum-based foam materials, including absorbent hygiene products such as sanitary pads.
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| 48. |
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| 49. |
- Cassimjee, Karim Engelmark, et al.
(author)
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Streamlined Preparation of Immobilized Candida antarctica Lipase B
- 2017
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:12, s. 8674-8677
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Journal article (peer-reviewed)abstract
- Candida antarctica lipase B (CalB) was efficiently expressed (6.2 g L-1) in Escherichia coli by utilizing an N-terminal tag cassette and the XylS/Pm expression system in a fed-batch bioreactor; subsequent direct binding to EziG from crude extracts resulted in an immobilized catalyst with superior activity to Novozym 435.
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| 50. |
- Ceylan, Fatma Duygu, et al.
(author)
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Combined Neutrase-Alcalase Protein Hydrolysates from Hazelnut Meal, a Potential Functional Food Ingredient
- 2023
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:1, s. 1618-1631
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Journal article (peer-reviewed)abstract
- Consumers' interest in functional foods has significantly increased in the past few years. Hazelnut meal, the main valuable byproduct of the hazelnut oil industry, is a rich source of proteins and bioactive peptides and thus has great potential to become a valuable functional ingredient. In this study, hazelnut protein hydrolysates obtained by a single or combined hydrolysis by Alcalase and Neutrase were mainly characterized for their physicochemical properties (SDS-PAGE, particle size distribution, Fourier-transform infrared (FTIR) spectroscopy, molecular weight distribution, etc.) and potential antiobesity effect (Free fatty acid (FFA) release inhibition), antioxidant activity (DPPH and ABTS methods), and emulsifying properties. The impact of a microfluidization pretreatment was also investigated. The combination of Alcalase with Neutrase permitted the highest degree of hydrolysis (DH; 15.57 ± 0.0%) of hazelnut protein isolate, which resulted in hydrolysates with the highest amount of low-molecular-weight peptides, as indicated by size exclusion chromatography (SEC) and SDS-PAGE. There was a positive correlation between the DH and the inhibition of FFA release by pancreatic lipase (PL), with a significant positive effect of microfluidization when followed by Alcalase hydrolysis. Microfluidization enhanced the emulsifying activity index (EAI) of protein isolates and hydrolysates. Low hydrolysis by Neutrase had the best effect on the EAI (84.32 ± 1.43 (NH) and 88.04 ± 2.22 m2/g (MFNH)), while a negative correlation between the emulsifying stability index (ESI) and the DH was observed. Again, the combined Alcalase-Neutrase hydrolysates displayed the highest radical scavenging activities (96.63 ± 1.06% DPPH and 98.31 ± 0.46% ABTS). FTIR results showed that the application of microfluidization caused the unfolding of the protein structure. The individual or combined application of the Alcalase and Neutrase enzymes caused a switch from the β-sheet organization of the proteins to α-helix structures. In conclusion, hazelnut meal may be a good source of bioactive and functional peptides. The control of its enzymatic hydrolysis, together with an appropriate pretreatment such as microfluidization, may be crucial to achieve the best suitable activity.
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