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At least 1,117 records · Page 62

Quantum Chemical Simulation of the Interaction of Functional Groups in Polyurethanes with 3d-Metal Ions During Their Extraction from Aqueous Solutions

The interaction of the functional groups in the polyurethane foam adsorbent Penopurm{sup ®} with the cations of some 3d-metals upon their extraction from aqueous solutions has been studied by atomic emission spectroscopy, UV/Vis and vibrational IR spectroscopy, and quantum chemical simulation using density functional theory. Penopurm{sup ®} absorbs 3d-metal cations from aqueous solutions in the pH range 5–7. Some spectral criteria have been found indicating a predominant interaction of Ni{sup 2+} ions with various fragments of the polyurethane foam structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Application of Multivariate Curve Resolution–Alternate Least Square Technique on Extracting Pure Spectral Components from Multiple Emitting Systems: a Case Study

Multiple emitting components in a fluorophoric system often produce complicated emission spectra. Extracting the individual spectral information from the composite spectra is important in order to comprehend the photophysical processes occurring in the multifluorophoric systems. Although the combination of Principal Component Analysis and Multivariate Curve Resolution-Alternate Least Square (PCA/MCR-ALS) technique is a well-known approach for curve deconvolution, its applicability in the spectral deconvolution of vibronically and electronically mixed up emitting systems as well as systems merged up with multiple electronic bands without a priori knowledge of the individual emitting species, is not properly studied. The present work highlights the strength of PCA/MCR-ALS in retrieving pure spectral information from the set of complex spectra arising out of the regular variation of causative factors that result in the variation of spectral composition. The retrieval of the emission bands utilizing the PCA/MCR-ALS technique has been made without having a priori information of the emitting species present in the multifluorophoric systems and the resolved spectra correspond well with the fluorescence spectra of the individual chemical species. The common curve fitting methods such as Gaussian and Lorentzian techniques have been found to be unsuccessful in providing meaningful photophysical information through the retrieved spectra. A comparative study of the curve fitting techniques MCR-ALS, Gaussian and Lorentzian in a set of complicated emission spectra of (i) pyrene and its excimer, (ii) pyrene and its excimer in presence of benzo[a]pyrene, and (iii) fisetin in bile salt medium is presented herein in details.

74 ATOMIC AND MOLECULAR PHYSICS↗

Extraction of radium and actinium with Pb resin and Rose Bengal

The extraction of radium and actinium with Eichrom Pb resin and Rose Bengal has been studied. Radium and actinium both show a strong affinity (k’ > 10,000) for the resin at intermediate pHs (~ 5–7) from solutions with Rose Bengal. The pH range and magnitude of uptake for both radium and actinium is significantly increased by the presence of Rose Bengal compared to basic solutions without this counter ion. Additionally, radium uptake is extremely fast from basic solutions with and without Rose Bengal; actinium uptake is slower, particularly in solutions without Rose Bengal. Column studies show that despite the similar behavior of actinium and radium in this system, separations of these two elements with Pb resin and Rose Bengal solutions are possible with reasonable yields due to the differences in uptake kinetics.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Preventing Wetting Between Liquid Copper and Solid Steel: A Simple Extraction Technique

Copper contamination of end-of-life steel scrap is the main barrier to high-quality recycling. Preferential melting of copper from solid steel scrap is a potential extraction technique, which could be integrated into conventional scrap re-melting with little additional energy. However, previous investigations show removal of liquid copper is limited by its adherence to solid scrap. Preventing wetting between liquid copper and steel is essential to enable separation. The carbon content of steel, initial surface oxidation, and applied coatings effect wetting behavior, but have not been systematically studied. In this study, the individual and combined effects of these parameters on wetting behavior in an inert gaseous environment are observed with a heating microscope. Carbon content appears to be the most significant factor: blistering of the oxide scale on medium-carbon steels causes liquid copper to flow rapidly between the oxide and steel substrate. Liquid copper exhibited a stable droplet on low-carbon steel, regardless of the initial level of oxidation. The tested coatings did not consistently improve nonwetting behavior, but impaired the connection between the scale and steel substrate. This study confirms the potential of the preferential melting technique, but further investigation is needed to determine the most robust process conditions to handle diverse, fragmented scrap at an industrial scale.

36 MATERIALS SCIENCE↗

Techno-Economic Analysis of Magnesium Extraction from Seawater via a Catalyzed Organo-Metathetical Process

Magnesium (Mg) has many useful applications especially in various Mg alloys which can decrease weight while increasing strength. To increase the affordability and minimize environment consequence, a novel catalyzed organo-metathetical (COMET) process was proposed to extract Mg from seawater aiming to achieve significant reduction in total energy and production cost comparing with the melting salt electrolysis method currently adopted by US Mg LLC. A process flowsheet for a reference COMET process was set-up using Aspen Plus which included five key steps, anhydrous MgCl2 production, transmetallation, dibutyl Mg decomposition, n-BuLi regeneration, and LiCL electrolysis. The energy and production cost and CO2 emission were estimated based on the Aspen modeling using Aspen economic analyzer. Our results showed that it is possible to produce Mg from seawater with a production cost of $2.0/kg-Mg while consuming about 35.3 kWh/kg-Mg and releasing 7.0 kg CO2/kg-Mg. A simplified US Mg manufacturing process was also generated using Aspen and the cost and emission results were estimated for comparison purpose. Under our simulation conditions, the reference COMET process maintain a comparable CO2 emission rate and can save about 40% in production cost and save about 15% energy compared to the simplified US Mg process.

Liu, Jian (ORCID:0000000153297408)↗

Cantilever Functionalization Using Peroxidase Extract of Low Cost for Glyphosate Detection

A cantilever nanobiosensor functionalized with vegetable source of peroxidase was developed as an innovative way for glyphosate herbicide detection over a wide concentration range (0.01 to 10 mg L{sup −1}) using atomic force microscopy (AFM) technique. The extract obtained from zucchini (Cucurbita pepo source of peroxidase), with high enzymatic activity and stability has been used as bio-recognition element to develop a nanobiosensor. The polarization-modulated reflection absorption infrared spectroscopy (PM-RAIRS) demonstrated the deposition of enzyme on cantilever surface using self-assembled monolayers (SAM) by the presence of the amide I and II bands. The detection mechanism of glyphosate was based on the changes in surface tension caused by the analyte adsorption, resulting in a conformational change in the enzyme structure. In this way, the results of nanobiosensor demonstrate the potential of the sensing device for detecting glyphosate with a detection limit of 0.028 mg L{sup −1}.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Bistability analysis in mathematical model of M-phase control in Xenopus oocyte extracts

To gain more insight into the molecular mechanism that regulates eukaryotic cell cycle, we propose a modification to an existing Mathematical model of mitosis-promoting factor control in Xenopus oocyte extract. To achieve this, we redirect how cell exits from mitosis using ubiquitin ligase enzyme APCP:Cdc20 which is acting as a modifier in cyclin degradation. We present a modified wiring map using combination of mass action kinetics and Michaelis–Menten kinetics to represent the biochemical processes. This results in a system of non-linear ordinary differential equations. The equilibria of the system were analyzed analytically. Using MPF as a bifurcation parameter, we analytically derived conditions under which bistability can occur in the MPF activation module. We find that for bistability to occur, it is necessary that the rate of phosphorylation of Wee1 must be greater than the rate of its dephosphorylation and that the concentration of MPF must lie in certain range of parameter values. Numerical simulations conducted show that the time taken to exit the cell cycle is shorter than those published in some reports and the sensitivity analysis results suggest that the rate of synthesis of cyclin is the most sensitive parameter in the dynamics of cell cycle. Through numerical experiments, we found new parameter sets that will give rise to bistability in the MPF activation module.

97 MATHEMATICS AND COMPUTING↗

Reducing systematic bias in machine learning applications to J/ψ signal extraction in high-energy nuclear physics

Machine learning techniques are increasingly used in high-energy nuclear physics because they can exploit multivariate correlations more efficiently than conventional cut-based analyses. A central challenge is the construction of training samples that faithfully reproduce the detector response observed in data. Signal samples are usually derived from detector simulations; therefore, mismatches between simulation and data can degrade classifier performance and introduce systematic biases. This work presents two practical correction procedures, namely cumulative distribution function (CDF) mapping and a shift-and-scale transformation, to align simulated signal features with those measured in data. Their performance is demonstrated with $J$/$\psi$ yield measurements in $\sqrt{s_{nn}}$ = 200 GeV Ru+Ru and Zr+Zr collisions recorded by STAR. A set of self-consistency tests shows that these procedures substantially suppress the systematic bias associated with data-simulation discrepancies in machine-learning-based signal extraction.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Combinations of NIR, Raman spectroscopy and physicochemical measurements for improved monitoring of solvent extraction processes using hierarchical multivariate analysis models

The reliability of chemical processes can be greatly improved by implementing inline monitoring systems. Combining multivariate analysis with non-destructive sensors can enhance the process without interfering with the operation. Here, we present here hierarchical models using both principal component analysis and partial least square analysis developed for different chemical components representative of solvent extraction process streams. A training set of 380 samples and an external validation set of 95 samples were prepared and Near infrared and Raman spectral data as well as conductivity under variable temperature conditions were collected. The results from the models indicate that careful selection of the spectral range is important. By compressing the data through Principal Component Analysis (PCA), we lower the rank of the data set to its most dominant features while maintaining the key principal components to be used in the regression analysis. Within the studied data set, concentration of five chemical components were modeled; total nitrate (NO 3 - ), total acid (H + ), neodymium (Nd 3+ ), sodium (Na + ), and ionic strength (I.S.). The best overall model prediction for each of the species studied used a combined data set comprised of complementary techniques including NIR, Raman, and conductivity. Finally, our study shows that chemometric models are powerful but requires significant amount of carefully analyzed data to capture variations in the chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Automated extraction of interfacial dislocations and disconnections from atomistic data

Here we introduce Interfacial Line Defect Analysis (ILDA), a method for identifying and extracting interfacial dislocations and disconnections with little-to-no input from the user on the nature of the interface. By simply providing the orientations and coherency strains for the crystals in a coherent reference state of the interface, ILDA provides exact Burgers vectors. Alternatively, these orientations and strains can be estimated using local atomic deformation gradients, making ILDA fully automated and providing estimated Burgers vectors. ILDA also determines the step height associated with each defect line segment, in case the associated defect is a disconnection. The heart of the method is the identification of atoms residing at co-incidence sites between the two crystals and the construction of a surface mesh connecting these sites that is used to compose Burgers circuits and insert defect line segments. We demonstrate the performance of ILDA in two test cases: a twist grain boundary and a phase boundary.

36 MATERIALS SCIENCE↗

Amniotic membrane extracted proteins protect H9c2 cardiomyoblasts against hypoxia-induced apoptosis by modulating oxidative stress

Highlights: • Hypoxia induces cell injury and apoptosis in H9c2 cells. • AMPs pre-treatment reinforce the antioxidant and anti-apoptosis properties in H9c2 cells against hypoxia. • AMPs regulate ROS balance, caspase 3 activation and Bcl2 family protein expression in H9c2 cells. Protection of the cardiac cell against hypoxia-induced cell damage is one of the main approaches to preventing cardiovascular disease. Earlier studies have shown the cardioprotective effect of the human Amniotic Membrane (hAM) in animal model of cardiac injury. However, the effect of Amniotic Membrane Proteins (AMPs), extracted from hAM, on myocardial hypoxia injury remains unclear. So, our study aimed to investigate the protective effect of AMPs against hypoxia-induced cardiomyocytes apoptosis. H9c2 cardiomyocytes were pre-treated with AMPs followed by 24 h in hypoxia condition. Cell viability and apoptotic induction were detected by MTT and PI staining assay. Furthermore, the reactive oxygen species (ROS) generation, caspase-3 activity and malondialdehyde (MDA) were measured using the relevant kits. Moreover, apoptosis associated molecules and NF-kB p65 subunit, the master regulator of inflammation; expression was measured by western blotting. Our results indicated that AMPs increased the cellular viability of H9c2 cells during hypoxia and attenuated apoptotic induction. AMPs reduced hypoxia-induced ROS generation and as indicated by decreased MDA content. Moreover, AMPs decreased Bax/Bcl-2 ratios followed by reduction the caspase-3 activity; and further repressed the phosphorylated NF-kB p65. Altogether, suggesting that AMPs offers cardioprotective effects to H9c2 cell in hypoxia condition by modulating the gene involved in apoptosis and reducing oxidative stress and inflammatory response.

60 APPLIED LIFE SCIENCES↗

Green synthesis and characterization of silver nanoparticles using Enicostemma axillare (Lam.) leaf extract

Highlights: • Green synthesis of AgNPs is using Enicostemma axillare. • Characterization of AgNPs was done by TEM, SEM and XRD. • The synthesized AgNP solution was stable for more than two months. • The method was eco-friendly, benign and cost-effective. In the present article, the facile green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Enicostemma axillare (Lam.) has reported. This is a simple, cost-effective, stable for a long time and reproducible aqueous synthesis method to obtain a self-assembly Ag nanoparticles. The size and shape of Ag nanoparticles were characterized by XRD, TEM, and SEM-EDS. The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV–Vis spectrophotometer analysis. Zeta potential was confirmed by DLS study. The mean particle diameter of silver nanoparticles was calculated from the TEM, SEM and the size of the particles was measured between 15 and 20 nm. TEM analysis revealed the spherical shape of the particles. Crystalline nature of the nanoparticles in the face-centred cubic structure are confirmed by the peaks in the XRD pattern corresponding to (111), (200), (220) and (311) planes. This study showed the biogenic, environmentally friendly and cost-effective synthesis and characterization of the silver nanoparticles.

60 APPLIED LIFE SCIENCES↗

Physical model and experimental validation of a high temperature proton exchange membrane electrochemical hydrogen pump cell for efficient single-stage extraction of low concentration hydrogen gas

There is interest in valorization of existing natural gas infrastructure to facilitate the co-transportation of hydrogen via blending of hydrogen gas initially at limited concentrations of 1–20 vol% H2 and to subsequently extract hydrogen at fuel cell quality standards (SAE J2719/ISO14687-2). High temperature proton exchange membrane electrochemical hydrogen pump (HT-PEM EHP) based on phosphoric acid doped polybenzimidazole (PA-PBI) exhibits good performance at elevated temperatures (>120 °C), which provides desirable tolerance to non-methane natural gas constituents that are problematic for lower temperature based EHP. To better understand the suitability of the HT-PEM EHP for such gas separation processes, a two-dimensional model of EHP based on PA-PBI was developed. The model is validated for several relevant operating conditions and across cells with differing amounts of phosphoric acid content in the electrodes. Operando micro x-ray computed tomography (CT) imaging of an HT-PEM EHP was used to further validate physical parameters and assumptions of the model. The impacts of pressure, relative humidity of the anode feed, and concentration of feed gases on separation performance are investigated. This study shows that a specific energy of separation of 5.1 kWh/kg H2 at a hydrogen recovery factor (HRF) of 50 vol% can be achieved in a single stage with the EHP, producing fuel cell quality hydrogen purity of 99.99 vol% H2 from a 2 vol% H2/CH4 feed blend, while pressurizing the product H2 at a pressure ratio of 1.3 relative to feed pressure.

Stansberry, John M↗

Automated thermal extraction-desorption gas chromatography mass spectrometry: A multifunctional tool for comprehensive characterization of polymers and their degradation products

The TED-GC–MS analysis is a two-step method. A sample is first decomposed in a thermogravimetric analyzer (TGA) and the gaseous decomposition products are then trapped on a solid-phase adsorber. Subsequently, the solid-phase adsorber is analyzed with thermal desorption gas chromatography mass spectrometry (TDU-GC–MS). This method is ideally suited for the analysis of polymers and their degradation processes. A new entirely automated system is introduced which enables high sample throughput and reproducible automated fractioned collection of decomposition products. The fractionated collection together with low temperatures reduces the risk of contamination, improves instrumental stability and minimizes maintenance efforts. Through variation of the two main parameters (purge gas flow and heating rate) it is shown how the extraction process can be optimized. By measuring the decomposition products of polyethylene it is demonstrated that compounds with masses of up to 434 Da can be detected. This is achieved despite the low temperature (˜40 °C) of the solid-phase adsorber and the low thermal desorption temperature of 200 °C in the TDU unit. It is now shown that automated TED-GC–MS represents a new flexible multi-functional method for comprehensive polymer analyses. Comparable polymer characterization was previously only achievable through a combination of multiple independent analytical methods. This is demonstrated by three examples focused on practical challenges in materials analysis and identification: The first one is the analysis of wood plastic composites for which the decomposition processes of the polymer and the bio polymer (wood) could be clearly distinguished by fractionated collection using sequential adsorbers. Secondly, a fast quantitative application is shown by determining the weight concentrations of an unknown polyolefin blend through comparison with a reference material. Additionally, the determination of microplastic concentrations in environmental samples is becoming an increasingly important analytical necessity. It is demonstrated that with TED-GC–MS calibration curves showing good linearity for the most important precursors for microplastic, even complex matrix materials (suspended particulate matter) can be successfully analyzed.

36 MATERIALS SCIENCE↗

Extraction chromatography of 225 Ac and lanthanides on N,N-dioctyldiglycolamic acid /1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide solvent impregnated resin

The alpha-emitter 225 Ac (t 1/2 = 9.92 d) is currently under development for targeted alpha-particle therapy of cancer, and accelerator production of 225 Ac via proton irradiation of thorium targets requires robust separations of 225 Ac from chemically similar fission product lanthanides. Additionally, the lanthanide elements represent critical components in modern technologies, and radiolanthanides such as 140 Nd (t 1/2 = 3.37 d) also have potential application in the field of nuclear medicine. The ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf 2 ]), combined with the diglycolamide extractant, N,N-dioctyldiglycolamic acid (DODGAA), was adsorbed on macroporous resin support to produce a solvent impregnated resin (SIR) that was investigated for separations of 225 Ac and lanthanides. The equilibrium distribution coefficients (Kd) of the rare earth elements (Sc(III), Y(III), Ln(III)), 225 Ac(III), Th(IV), and U(VI) on the prepared DODGAA/[Bmim][NTf 2 ]-SIR were determined from batch adsorption experiments in HCl and HNO 3 media. The DODGAA/[Bmim][NTf2]-SIR exhibited preferential uptake of the heavier lanthanide elements while allowing for the separation of the lighter lanthanides. Column separations utilizing the DODGAA/[Bmim][NTf 2 ]-SIR were effective at separating the lighter lanthanides from each other, and separating 225 Ac from a mixture of lanthanides, 213 Bi, and 225 Ra without the need for additional complexing agents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Rare earth ion-adsorption clays in the presence of iron at basic pH: Adsorption mechanism and extraction method

In this work, the uptake mechanism and influence of iron (Fe) co-adsorption on the binding of rare-earth elements (REEs) on kaolinite have been investigated. REEs and varying concentrations of Fe were co-adsorbed onto kaolinite at pH 10.5. Inductively coupled plasma mass spectrometry (ICP-MS), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize how Fe co-adsorption influenced the uptake mechanism of REEs on kaolinite. Elemental analysis by ICP-MS revealed that the REE concentrations on kaolinite were unaffected by the presence of Fe. Crystal structure of kaolinite, determined by PXRD, was not altered after REE and Fe co-adsorption. XPS suggests that the adsorbed Fe is in the form of FeOOH, while the greatly attenuated REE XPS signals upon Fe co-adsorption implies that REEs are encapsulated by Fe species. Based on these results, we conclude that FeOOH layers were formed on top of REEs on the surface of kaolinite. Synthesized REE-Fe-kaolinite samples respond poorly to ion-exchange leaching, indicating that Fe is detrimental to the REE ion-exchange efficiency. The inhibition of ion-exchange REE extraction appears to be due to the passivating FeOOH layers. In contrast to ion-exchange methods, reductive leaching was found to dissolve the FeOOH passivating layers and liberate REEs such that they became available for ion-exchange leaching.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Potassium carbonate decomposition modeling within rotating detonation engines for direct power extraction applications

We report that recently, there has been a significant interest in detonation-based combustion systems, such as rotating detonation engines (RDE), due to potential performance advantages in propulsion and energy applications. This includes improvements in thermodynamic efficiency, inherently high gas velocities, and the possibility of achieving an increase in total pressure (i.e. pressure gain) through the combustion process. Due to approximating a constant volume combustion process, these devices also tend to exhibit extremely high local gas temperatures relative to a comparable constant pressure combustor. These advantages overlap well with desirable performance characteristics of direct power extraction (DPE) technologies, such as a magnetohydrodynamic (MHD) generator. Typically, in DPE systems hot combustion products are seeded with an easily ionizable material such as potassium carbonate (K 2 CO 3 ) in order to boost the electrical conductivity. However, due to the short gas residence times within an RDE, it was unclear whether forming an electrically conductive combustion plasma would be feasible for integration with a downstream MHD generator. A model is presented which describes the heating, decomposition, and ionization of solid K 2 CO 3 particles and aqueous solutions of K 2 CO 3 in water, for a given initial particle diameter. This model was combined with available computational fluid dynamics (CFD) data for an oxygen-methane RDE in a one-way coupled Eulerian-Lagrangian framework to predict particle trajectories and the corresponding heating, decomposition, and ionization histories. Electrical conductivities were computed using a previously developed model, and a method was proposed to determine an equivalent average electrical conductivity. Results show that particle sizes below ~30 µm are able to fully decompose before reaching the exit of the RDE. While the one-way coupled nature of the simulations precluded rigorous evaluation of the effects of seed material on detonability, a substantial temperature reduction is expected at the detonation wave front due to heating and decomposition. A preliminary comparison is presented between the RDE and an equivalent constant pressure adiabatic combustor, showing a potential performance advantage for the RDE.

42 ENGINEERING↗

Oil extraction in the Amazon basin and exposure to metals in indigenous populations

Highlights: • We assessed the body burdens of metals in two kukama communities after oil spills. • Median Hg levels were above values recommended by the Peruvian Ministry of Health. • 50% of the population had Hg levels higher than those recommended. • 17% of the study population had Cd levels higher than those recommended. • Oil spills may be a source of exposure to metals but other sources may contribute. Most oil extraction areas in the Peruvian Amazon are within indigenous territories. Poor environmental practices have exposed the indigenous population to metals. We conducted a survey in two indigenous Kukama communities to assess body burdens of metals after the occurrence of two major oil spills in 2014. Urine levels above those recommended by the Peruvian Ministry of Health were observed in 50% and 17% of the study population for mercury and cadmium, respectively.

54 ENVIRONMENTAL SCIENCES↗