| 1. |
- Bu, Xiangning, et al.
(författare)
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Exploring the Relationships between Gas Dispersion Parameters and Differential Pressure Fluctuations in a Column Flotation
- 2021
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Ingår i: ACS Omega. - : Elsevier. - 2470-1343. ; 6:34, s. 21900-21908
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Chipakwe, Vitalis, 1990-, et al.
(författare)
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Nanobubble-Assisted Flotation of Apatite Tailings : Insights on Beneficiation Options
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:21, s. 13888-13894
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Tidskriftsartikel (refereegranskat)abstract
- Processing of materials that originated from tailings of industrial plants (with a wide range of particle size distribution, “PSD”) without grinding has several advantages since mines are faced with a lot of pressure to minimize their environmental impacts. This article indicates that the introduction of submicron bubbles (known as nanobubbles, “NBs”) to conventional flotation could improve the separation efficiency of valuable minerals from their associated gangue phases. It was demonstrated that metallurgical responses (recovery, grade, selectivity, and kinetics) of NB flotation could improve compared to those of conventional tests. Various hydrodynamic cavitation setups for NB generation may lead to different metallurgical responses. In general, the addition of surfactants (frothers and collectors) for NB generation could increase both mass and water recoveries, which would be key factors on selectivity. Selectivity is also markedly dependent on the PSD of feed, and the selectivity of NB flotation is improved significantly by decreasing the feed size. In general, generation of NBs in the presence of a frother leads to higher flotation metallurgical responses than in the presence of a collector.
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| 3. |
- El Jamal, Sawsan, et al.
(författare)
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On the Stability of Uranium Carbide in Aqueous Solution-Effects of HCO3- and H2O2
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:37, s. 24289-24295
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Tidskriftsartikel (refereegranskat)abstract
- Uranium carbide (UC) is a candidate fuel material for future Generation IV nuclear reactors. As part of a general safety assessment, it is important to understand how fuel materials behave in aqueous systems in the event of accidents or upon complete barrier failure in a geological repository for spent nuclear fuel. As irradiated nuclear fuel is radioactive, it is important to consider radiolysis of water as a process where strongly oxidizing species can be produced. These species may display high reactivity toward the fuel itself and thereby influence its integrity. The most important radiolytic oxidant under repository conditions has been shown to be H2O2. In this work, we have studied the dissolution of uranium upon exposure of UC powder to aqueous solutions containing HCO3- and H2O2, separately and in combination. The experiments show that UC dissolves quite readily in aqueous solution containing 10 mM HCO3- and that the presence of H2O2 increases the dissolution further. UC also dissolves in pure water after the addition of H2O2, but more slowly than in solutions containing both HCO3- and H2O2. The experimental results are discussed in view of possible mechanisms.
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| 4. |
- Forghani Targhi, Bita, 1973, et al.
(författare)
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Biochemical Characterization and Storage Stability of Process Waters from Industrial Shrimp Production
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:46, s. 30960-30970
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Tidskriftsartikel (refereegranskat)abstract
- Shrimp boiling water (SBW) and shrimp peeling water (SPW), generated during shrimp processing, were characterized in terms of crude composition, volatile compounds, as well as nutritional and potentially toxic elements over a 13 month sampling period. The storage stability of both waters was also evaluated. Results showed that SBW contained on median 14.8 g/L protein and 2.2 g/L total fatty acids with up to 50% comprising eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Astaxanthin esters, which dominated the total astaxanthin, were 2.8 mg/L on median. SPW, on the other hand, contained on median 1.0 g/L of protein, 0.21 g/L of total fatty acids, and 1.2 mg/L astaxanthin esters. For both side-streams, essential amino acids were up to 50% of total amino acids. For SBW and SPW, the most abundant nutritional elements were Na, K, P, Ca, Cu, and Zn. The contents of all potentially toxic elements were below the detection limits, except for As. SBW was more stable at 4 °C compared to SPW as shown, e.g., by thiobarbituric acid reactive substances and relative changes in total volatile basic nitrogen. The extensive compositional mapping of SBW/SPW provides crucial knowledge necessary in the exploitation and value-adding of such side-streams into food or feed products.
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| 5. |
- Frisk, Junmei Hu, et al.
(författare)
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Biochemical Characterizations of Human TMPK Mutations Identified in Patients with Severe Microcephaly : Single Amino Acid Substitutions Impair Dimerization and Abolish Their Catalytic Activity
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:49, s. 33943-33952
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Tidskriftsartikel (refereegranskat)abstract
- Deoxythymidylate kinase (TMPK) is a key enzyme in the synthesis of deoxythymidine triphosphate (dTTP). Four TMPK variants (P81L, A99T, D128N, and a frameshift) have been identified in human patients who suffered from severe neurodegenerative diseases. However, the impact of these mutations on TMPK function has not been clarified. Here we show that in fibroblasts derived from a patient, the P81L and D128N mutations led to a complete loss of TMPK activity in mitochondria and extremely low and unstable TMPK activity in cytosol. Despite the lack of TMPK activity, the patient-derived fibroblasts apparently grew normal. To investigate the impact of the mutations on the enzyme function, the mutant TMPKs were expressed, purified, and characterized. The wild-type TMPK mainly exists as a dimer with high substrate binding affinity, that is, low Km value and high catalytic efficiency, that is, k(cat)/K-M. In contrast, all mutants were present as monomers with dramatically reduced substrate binding affinity and catalytic efficiencies. Based on the human TMPK structure, none of the mutated amino acids interacted directly with the substrates. By structural analysis, we could explain why the respective amino acid substitutions could drastically alter the enzyme structure and catalytic function. In conclusion, TMPK mutations identified in patients represent loss of function mutations but surprisingly the proliferation rate of the patient-derived fibroblasts was normal, suggesting the existence of an alternative and hitherto unknown compensatory TMPK-like enzyme for dTTP synthesis. Further studies of the TMPK enzymes will help to elucidate the role of TMPK in neuropathology.
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| 6. |
- Garskaite, Edita, et al.
(författare)
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The Accessibility of the Cell Wall in Scots Pine (Pinus sylvestris L.) Sapwood to Colloidal Fe3O4 Nanoparticles
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:33, s. 21719-21729
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a rapid and facile way to access the cell wall of wood with magnetic nanoparticles (NPs), providing insights into a method of wood modification to prepare hybrid bio-based functional materials. Diffusion-driven infiltration into Scots pine (Pinus sylvestris L.) sapwood was achieved using colloidal Fe3O4 nanoparticles. Optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray powder diffraction analyses were used to detect and assess the accessibility of the cell wall to Fe3O4. The structural changes, filling of tracheids (cell lumina), and NP infiltration depth were further evaluated by performing X-ray microcomputed tomography analysis. Fourier transform infrared spectroscopy was used to assess the chemical changes in Scots pine induced by the interaction of the wood with the solvent. The thermal stability of Fe3O4-modified wood was studied by thermogravimetric analysis. Successful infiltration of the Fe3O4 NPs was confirmed by measuring the magnetic properties of cross-sectioned layers of the modified wood. The results indicate the feasibility of creating multiple functionalities that may lead to many future applications, including structural nanomaterials with desirable thermal properties, magnetic devices, and sensors.
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| 7. |
- Hajizadeh, Solmaz, et al.
(författare)
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Synthesizing a Hybrid Nanocomposite as an Affinity Adsorbent through Surface-Initiated Atom Transfer Radical Polymerization Catalyzed by Myoglobin
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:15, s. 10462-10474
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid bifunctional core-shell nanostructure was synthesized for the first time via surface-initiated atom transfer radical polymerization (SI-ATRP) using myoglobin as a biocatalyst (ATRPase) in an aqueous solution. N-Isopropyl acrylamide (NIPA) and N-(3-aminopropyl)methacrylamide (APMA) were applied to graft flexible polymer brushes onto initiator-functionalized silica nanoparticles. Two different approaches were implemented to form the core-shell nanocomposite: (a) random copolymerization, Si@p(NIPA-co-APMA) and (b) sequential block copolymerization, Si@pNIPA-b-pAPMA. These nanocomposites can be used as versatile intermediates, thereby leading to different types of materials for targeted applications. In this work, a phenylboronic acid ligand was immobilized on the side chain of the grafted brushes during a series of postmodification reactions to create a boronate affinity adsorbent. The ability to selectively bind glycoproteins (ovalbumin and glycated hemoglobin) via boronic acid was assessed at two different temperatures (20 and 40 °C), where Si@pNIPA-b-APMABA (163 mg OVA/g of particle) displayed an approximately 1.5-fold higher capacity than Si@p(NIPA-co-APMA)BA (107 mg OVA/g of particle). In addition to selective binding to glycoproteins, the nanocomposites exhibited selective binding for myoglobin due to the molecular imprinting effect during the postmodification process, that is, 72 and 111 mg Mb/g for Si@p(NIPA-co-APMA)BA and Si@pNIPA-b-pAPMABA, respectively.
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| 8. |
- Honcharenko, Dmytro, et al.
(författare)
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New Alkyne and Amine Linkers for Versatile Multiple Conjugation of Oligonucleotides
- 2021
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Ingår i: ACS Omega. - : American Chemical Society. - 2470-1343. ; 6:1, s. 579-593
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Tidskriftsartikel (refereegranskat)abstract
- Oligonucleotide (ON) conjugates are increasingly important tools for various molecular diagnostics, nanotechnological applications, and for the development of nucleic acid-based therapies. Multiple labeling of ONs can further equip ON-conjugates and provide improved or additional tailored properties. Typically, the preparation of ON multiconjugates involves additional synthetic steps and/or manipulations in post-ON assembly. This report describes the simplified methodology allowing for multiple labeling of ONs on a solid support and is compatible with phosphodiester as well as phosphorothioate (PS) ONs. The current approach utilizes two novel alkyne- A nd amino-functionalized linker phosphoramidites that can be readily synthesized from a common aminodiol intermediate in three steps. The combination of new linkers provides orthogonal functionalities, which allow for multiple attachments of similar or varied moieties. The linkers are incorporated into ONs during automated solid-phase ON synthesis, and the conjugation with functional entities is achieved by either amide bond formation or by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The versatility of the approach is demonstrated by the synthesis of 5′-site ON multiconjugates with small molecules, peptides, and fatty acids as well as in the preparation of an internal peptide-ON conjugate.
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| 9. |
- Kaindl, Reinhard, et al.
(författare)
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Aerosol Jet Printing of Graphene and Carbon Nanotube Patterns on Realistically Rugged Substrates
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:50, s. 34301-34313
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Tidskriftsartikel (refereegranskat)abstract
- Direct-write additive manufacturing of graphene and carbon nanotube (CNT) patterns by aerosol jet printing (AJP) is promising for the creation of thermal and electrical interconnects in (opto)electronics. In realistic application scenarios, this however often requires deposition of graphene and CNT patterns on rugged substrates such as, for example, roughly machined and surface oxidized metal block heat sinks. Most AJP of graphene/CNT patterns has thus far however concentrated on flat wafer-or foil type substrates. Here, we demonstrate AJP of graphene and single walled CNT (SWCNT) patterns on realistically rugged plasma electrolytic-oxidized (PEO) Al blocks, which are promising heat sink materials. We show that AJP on the rugged substrates offers line resolution of down to similar to 40 mu m width for single AJP passes, however, at the cost of noncomplete substrate coverage including noncovered mu m-sized pores in the PEO Al blocks. With multiple AJP passes, full coverage including coverage of the pores is, however, readily achieved. Comparing archetypical aqueous and organic graphene and SWCNT inks, we show that the choice of the ink system drastically influences the nanocarbon AJP parameter window, deposit microstructure including crystalline quality, compactness of deposit, and inter/intrapass layer adhesion for multiple passes. Simple electrical characterization indicates aqueous graphene inks as the most promising choice for AJP-deposited electrical interconnect applications. Our parameter space screening thereby forms a framework for rational process development for graphene and SWCNT AJP on application-relevant, rugged substrates.
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| 10. |
- Khan, Inayat, et al.
(författare)
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Zinc-Coordination Polymer-Derived Porous Carbon-Supported Stable PtM Electrocatalysts for Methanol Oxidation Reaction
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:10, s. 6780-6790
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Tidskriftsartikel (refereegranskat)abstract
- Porous carbon (PC) is obtained by carbonizing a zinc-coordination polymer (MOF-5) at 950 °C and PtM (M = Fe, Co, Ni, Cu, Zn) nanoparticles (NPs), which are deposited on PC using the polyol method. Structural and morphological characterizations of the synthesized materials are carried out by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM), and the porosity was determined using a N2 adsorption/desorption technique. The results revealed that PtM NPs are alloyed in the fcc phase and are well dispersed on the surface of PC. The electrochemical results show that PtM/PC 950 catalysts have higher methanol oxidation reaction (MOR) performances than commercial Pt/C (20%) catalysts. After 3000 s of chronoamperometry (CA) test, the MOR performances decreased in the order of Pt1Cu1/PC 950 > Pt1Ni1/PC 950 > Pt1Fe1/PC 950 > Pt1Zn1/PC 950 > Pt1Co1/PC 950. The high MOR activities of the synthesized catalysts are attributed to the effect of M on methanol dissociative chemisorption and improved tolerance of Pt against CO poisoning. The high specific surface area and porosity of the carbon support have an additional effect in boosting the MOR activities. Screening of the first row transition metals (d5+n, n = 1, 2, 3, 4, 5) alloyed with Pt binary catalysts for MOR shows that Pt with d8 (Ni) and d9 (Cu) transition metals, in equivalent atomic ratios, are good anode catalysts for alcohol fuel cells.
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