ACS Omega

Journal: ACS Omega

Abbreviation

ACS Omega

Publisher

American Chemical Society

ISSN

2470-1343

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Publications 1 - 10 of 47

Barium-Promoted Yttria-Zirconia-Supported Ni Catalyst forHydrogen Production via the Dry Reforming of Methane: Role ofBarium in the Phase Stabilization of Cubic ZrO2 br
Al-Fatesh, Ahmed Sadeq; Patel, Rutu; Srivastava, Vijay Kumar; et al. (2022)
ACS Omega
:developing cost-effective nonprecious active metal-basedcatalysts for syngas (H2/CO) production via the dry reforming of methane(DRM) for industrial applications has remained a challenge. Herein, weutilized a facile and scalable mechanochemical method to develop Ba-promoted (1-5 wt %) zirconia and yttria-zirconia-supported Ni-basedDRM catalysts. BET surface area and porosity measurements, infrared,ultraviolet-visible, and Raman spectroscopy, transmission electronmicroscopy, and temperature-programmed cyclic (reduction-oxidation-reduction) experiments were performed to characterize and elucidate thecatalytic performance of the synthesized materials. Among differentcatalysts tested, the inferior catalytic performance of 5Ni/Zr was attributedto the unstable monoclinic ZrO2support and weakly interacting NiOspecies whereas the 5Ni/YZr system performed better because of the stablecubic ZrO2phase and stronger metal-support interaction. It is establishedthat the addition of Ba to the catalysts improves the oxygen-endowing capacity and stabilization of the cubic ZrO2and BaZrO3phases. Among the Ba-promoted catalysts, owing to the optimal active metal particle size and excess ionic CO32-species, the5Ni4Ba/YZr catalyst demonstrated a high, stable H2yield (i.e., 79% with a 0.94 H2/CO ratio) for up to 7 h of time on stream. The5Ni4Ba/YZr catalyst had the highest H2formation rate, 1.14 mol g-1h-1and lowest apparent activation energy, 20.07 kJ/mol,among all zirconia-supported Ni catalyst systems
Passive Sampling Tool for Actinides in Spent Nuclear Fuel Pools
Chaplin, Joshua D.; Christl, Marcus; Straub, Marietta; et al. (2022)
ACS Omega
Spent nuclear fuel must be carefully managed to prevent pollution of the environment with radionuclides. Within the framework of correct radioactive waste management, spent fuel rods are stored in cooling pools to allow short-lived fission products to decay. If fuel rods leak, they liberate radionuclides into the cooling water; therefore, it is essential to determine radionuclide concentrations in the pool water for monitoring purposes and to plan the decommissioning process. In this work, we present, to our knowledge, the first passive sampling technique for measures of actinides in spent nudear fuel pools, based on recently developed diffusive gradients in thin-film (DGT) configurations. These samplers eliminate the need to retrieve and handle large samples of fuel pool water for radiochemical processing by immobilizing their targeted radionuclides in situ on the solid phase within the sampler. This is additionally the first application of the DGT technique for Cm measure. Herein, we make the calibrated effective diffusion coefficients of U, Pu, Am, and Cm in borated spent fuel pool water available. We tested these samplers in the fuel pool of a nuclear facility and measured samples using accelerator mass spectrometry to provide high-precision isotopic reports, allowing for the first independent implementation of a recently developed technique for dating nuclear fuel based on its Cm isotope signature.
Effect of Template Type on the Trametes versicolor Laccase-Catalyzed Oligomerization of the Aniline Dimer p-Aminodiphenylamine (PADPA)
Kashima, Keita; Fujisaki, Tomoyuki; Serrano-Luginbühl, Sandra; et al. (2019)
ACS Omega
Many previous studies have shown that (i) the oxidation of aniline or the aniline dimer p-aminodiphenylamine (PADPA) in a slightly acidic aqueous solution can be catalyzed with heme peroxidases or multicopper laccases and that (ii) subsequent reactions lead to oligomeric or polymeric products, which resemble chemically synthesized polyaniline in its conductive emeraldine salt form (PANI-ES), provided that (iii) an anionic “template” is present in the reaction medium. Good templates are anionic polyelectrolytes, micelles, or vesicles. Under optimal conditions, their presence directs the reactions in a positive way toward the desired formation of PANI-ES-type products. The effect of four different types of anionic templates on the formation of PANI-ES-like products from PADPA was investigated and compared by using Trametes versicolor laccase (TvL) as a catalyst in an aqueous pH 3.5 solution at room temperature. All four templates contain sulfonate groups: the sodium salt of the polyelectrolyte sulfonated polystyrene (SPS), micelles from sodium dodecylbenzenesulfonate (SDBS), vesicles from a 1:1 molar mixture of SDBS and decanoic acid, and vesicles from sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Although with all four templates, stable, inkjet-printable solutions or suspensions consisting of PANI-ES-type products were obtained under optimized conditions, considerably higher amounts of TvL were required with SDBS micelles to achieve comparable monomer conversion to PANI-ES-like products during the same time period when compared to those with SPS or the two types of vesicles. This makes SDBS micelles less attractive as templates for the investigated reaction. In situ UV/vis/near-infrared, electron paramagnetic resonance (EPR), and Raman spectroscopy measurements in combination with an high-performance liquid chromatography analysis of extracted reaction products, which were deprotonated and chemically reduced, showed seemingly small but significant differences in the composition of the mixtures obtained when reaching reaction equilibrium after 24 h. With the two vesicle systems, the content of unwanted substituted phenazine units was lower than in the case of SPS polyelectrolyte and SDBS micelles. The EPR spectra indicate a more localized, narrower distribution of electronic states of the paramagnetic centers of the PANI-ES-type products synthesized in the presence of the two vesicle systems when compared to that of the similar products obtained with the SPS polyelectrolyte and SDBS micelles as templates. Overall, the data obtained from the different complementary methods indicate that with the two vesicle systems structurally more uniform (regular) PANI-ES-type products formed. Among the two investigated vesicle systems, for the investigated reaction (oxidation of PADPA with TvL and O2), AOT appears a somewhat better choice as it leads to a higher content of the PANI-ES polaron form.
Peptide Conjugates of a 2′-O-Methoxyethyl Phosphorothioate Splice-Switching Oligonucleotide Show Increased Entrapment in Endosomes
Hill, Alyssa C.; Becker, J. Philipp; Slominski, Daria; et al. (2023)
ACS Omega
Antisense oligonucleotides (ASOs) are short, single-stranded nucleic acid molecules that alter gene expression. However, their transport into appropriate cellular compartments is a limiting factor in their potency. Here, we synthesized splice-switching oligonucleotides (SSOs) previously developed to treat the rare disease erythropoietic protoporphyria. Using chemical ligation-quantitative polymerase chain reaction (CL-qPCR), we quantified the SSOs in cells and subcellular compartments following free uptake. To drive nuclear localization, we covalently conjugated nuclear localization signal (NLS) peptides to a lead 2′-O-methoxyethyl phosphorothioate SSO using thiol–maleimide chemistry. The conjugates and parent SSO displayed similar RNA target-binding affinities. CL-qPCR quantification of the conjugates in cells and subcellular compartments following free uptake revealed one conjugate with better nuclear accumulation relative to the parent SSO. However, compared to the parent SSO, which altered the splicing of the target pre-mRNA, the conjugates were inactive at splice correction under free uptake conditions in vitro. Splice-switching activity could be conferred on the conjugates by delivering them into cells via cationic lipid-mediated transfection or by treating the cells into which the conjugates had been freely taken up with chloroquine, an endosome-disrupting agent. Our results identify the major barrier to the activity of the peptide–oligonucleotide conjugates as endosomal entrapment.
Celebrating a Decade of ACS Omega: Reflections from the Editorial Roundtable
Ganesh, Krishna N.; Banerjee, Sarbajit; Quina, Frank H.; et al. (2025)
ACS Omega
Composites of Copper Nanowires in Polyethylene: Preparation and Processing to Materials with NIR Dichroism
Nydegger, Mirco; Deshmukh, Rupali; Tervoort, Elena; et al. (2019)
ACS Omega
Agglomeration of copper nanowires (aspect ratios on the order of 1000) in polyethylene, commonly a major problem, could be prevented by modification of the nanowires with a surface layer of oleylamine. Nanocomposite films were prepared by mixing nanowire dispersions in organic solvents with polyethylene solutions followed by casting, drying, and sometimes hot pressing. Orientation of the copper nanowires by solid-state drawing of the composites at elevated temperatures led to preferential alignment of the nanowires in the drawing direction. This arrangement gave rise to a uniform dichroism in the near-infrared (NIR) region, which is uncommon in the case of the hitherto reported dichroic nanocomposites. The NIR dichroism is ascribed to the high aspect ratio of the metal wires. Hence, drawing of isotropic nanocomposites with metal wires may serve for the manufacture of NIR polarization filters.
From pH- to Light-Response: Postpolymerization Modification of Polymer Brushes Grafted onto Microporous Polymeric Membranes
Dübner, Matthias; Naoum, Maria-Eleni; Spencer, Nicholas D.; et al. (2017)
ACS Omega
A microporous pH- and light-responsive membrane that enables remote control over its interfacial properties has been fabricated. pH-Responsiveness was imparted to a porous polypropylene film via grafting of poly(methacrylic acid) brushes from the substrate using argon-plasma-induced free-radical graft polymerization. Morphological changes as a function of grafting level were analyzed using atomic force microscopy. Conversion into a light-responsive membrane was performed via postpolymerization modification to covalently attach photochromic spiropyran moieties to the grafted polymer brushes. Reversible switches in wettability and permeability were determined upon changing from acidic to basic pH or upon alternating UV- and visible-light irradiation. Additionally, light-responsive membranes show a switch in color upon UV exposure.
Development of Hierarchically Porous Ionomer Membranes for Versatile and Fast Metal Ion Conduction
Hänsel, Christian; Kundu, Dipan (2019)
ACS Omega
Innovative design concepts can play a key role in the realization of high-performance ionomer membranes that are capable of exclusive metal ion conduction and potentially applicable in electrochemical devices including sensors, fuel cells, and high-energy batteries. Herein, we report on the development of new ionomers, based on sulfonated poly(ether ether ketone) (SPEEK), engineered to conduct a variety of ions, namely, Li+, Na+, K+, Zn2+, and Mg2+, when soaked with nonaqueous solvents. Application of a facile phase-inversion method results in M-SPEEK (M = Li/Na/K/Zn/Mg) membranes with a hierarchical porous network, facilitating organic solvent infusion that is necessary to promote dissociation and rapid transport of cations between anionic sulfonate groups on the polymer chains. This strategy leads to membranes with alkali ion conductivities approaching 10–4 S cm–1 at room temperature, and near unity cation transference numbers (tM+ ≥ 0.9). Furthermore, an exceptionally high Zn-ion conductivity of 10–2 S cm–1 is obtained for the water-infused Zn-SPEEK membrane. In comparison, the dense membranes demonstrate 2–3 orders of magnitude lower conductivities because of insufficient solvent infusion. Preliminary electrochemical studies with solvent-infused ionomer membranes as the electrolyte look promising.
Hydrotalcite-Derived Mixed Oxides for the Synthesis of a Key Vitamin A Intermediate Reducing Waste
Coumans, Ferdy J.A.G.; Mitchell, Sharon; Schütz, Jan; et al. (2018)
ACS Omega
The synthesis of hydroxenin monoacetate, a key intermediate in the manufacture of vitamin A, relies on the undesirable use of stoichiometric amounts of organic bases such as pyridine. Although the final product (vitamin A acetate) can be produced from hydroxenin diacetate, using the monoacetylated intermediate improves the overall process yield. Aiming to identify more efficient, environmentally benign alternatives, this work first studies the homogeneous acetylation reaction using pyridine. The addition of the base is found to enhance the rate of hydroxenin monoacetate formation, confirming its catalytic role, but also yields non-negligible amounts of hydroxenin diacetate. On the basis of these insights, Mg- and Al-containing hydrotalcites are explored because of their broad scope as base catalysts and the ability to finely tune their properties. The reaction kinetics are greatly enhanced via controlled thermal activation, forming high surface area mixed metal oxides displaying Lewis basic sites. In contrast, a Brønsted basic material synthesized by the reconstruction of a mixed oxide performs similarly to the as-synthesized hydrotalcite. Variation of the Mg/Al ratio from 1 to 3 has no significant impact, but activity losses are observed at higher values because of a reduced number of basic sites. After optimizing the reaction conditions, hydroxenin monoacetate yields >60% are obtained in five consecutive cycles without the need for any intermediate treatment. The findings confirm the potential of hydrotalcite-derived materials as highly selective catalysts for the production of vitamins with reduced levels of organic waste.
Anisotropic Magnetic Resonance in Random Nanocrystal Quantum Dot Ensembles
Almeida, António J.S.; Sahu, Ayaskanta; Norris, David J.; et al. (2020)
ACS Omega
Magnetic anisotropy critically determines the utility of magnetic nanocrystals (NCs) in new nanomagnetism technologies. Using angular-dependent electron magnetic resonance (EMR), we observe magnetic anisotropy in isotropically arranged NCs of a nonmagnetic material. We show that the shape of the EMR angular variation can be well described by a simple model that considers magnetic dipole–dipole interactions between dipoles randomly located in the NCs, most likely due to surface dangling bonds. The magnetic anisotropy results from the fact that the energy term arising from the magnetic dipole–dipole interactions between all magnetic moments in the system is dominated by only a few dipole pairs, which always have an anisotropic geometric arrangement. Our work shows that magnetic anisotropy may be a general feature of NC systems containing randomly distributed magnetic dipoles.

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