Papers by Sergio Granados
We assess the suitability of potassium ferri-/ferrocyanide as an electroactive species for long-t... more We assess the suitability of potassium ferri-/ferrocyanide as an electroactive species for long-term utilization in aqueous organic redox flow batteries. A series of electrochemical and chemical characterization experiments was performed to distinguish between structural decomposition and apparent capacity fade of ferri-/ferrocyanide solutions used in the capacity-limiting side of a flow battery. Our results indicate that, in contrast with previous reports, no structural decomposition of ferri-/ferrocyanide occurs at tested pH values as high as 14 in the dark or in diffuse indoor light. Instead, an apparent capacity fade takes place due to an electroless reduction of ferricyanide to ferrocyanide, via electroless oxygen evolution reaction. We find that this parasitic process can be further exacerbated by carbon electrodes, with apparent capacity fade rates at pH 14 increasing with an increased ratio of carbon electrode surface area to total amount of ferricyanide in solution. Based o...
In this study, ABC-type triblock copolymers, poly(ethylene glycol)-b-poly(e-caprolactone)-b-poly(... more In this study, ABC-type triblock copolymers, poly(ethylene glycol)-b-poly(e-caprolactone)-b-poly(2-(2aminoethyl amino) ethyl methacrylate)s (PEG-PCL-PAEAE-MAs), composed of novel poly(2-(2-aminoethyl amino) ethyl methacrylate) (PAEAEMA) that have a primary and a secondary amino group in each monomeric unit, were synthesized successfully. It was found that the length of PAEAEMA segments did not have obvious influence on the DNA-binding capacity and other biophysical properties (size and zeta potential values of polymer/pDNA complexes) , but longer PAEAEMA chains led to a better buffering capacity. The triblock copolymers could mediate efficient gene expression that was similar to branched 25-kDa polyethylenimine (25 kDa PEI) in the absence of serum and even superior to 25 kDa PEI in the presence of serum in COS-7 cells. Low cytotoxicity of these polymers was also found in COS-7 cells. As a result, PEG-PCL-PAEAEMAs are attractive candidates as serum-tolerable gene carriers in biomedical field. V
The distinctive microstructures in bitumen and their indication of bitumen’s phase stability
Bulletin of the American Physical Society, 2019
Physical chemistry chemical physics : PCCP, 2021
Solid-acid catalysts functionalized with catalytic groups have attracted intense interest for con... more Solid-acid catalysts functionalized with catalytic groups have attracted intense interest for converting cellulose into soluble products. However, design of solid-7 acid catalysts has been guided by molecular level interactions and the actual mechanism of cellulose-solid-acid catalyst particles adsorption remains unknown. Here, colloidal stability theory, DLVO, is used to rationalize the design of solid acids for targeted cellulose adsorption. In nearly all cases, an energy barrier, arising from electrostatic repulsion and much larger than the energy associated with thermal fluctuations, prevents close contact between the solid acid and cellulose. Polymer-based solid-acid substrates such as polystyrene and Nafion are especially ineffective as their interaction with cellulose is dominated by the repulsive electrostatic force. Carbon and metal oxides have potential to be effective for cellulose-solid-acid interaction as their attractive van der Waals interaction can offset the repulsi...
Thermoreversible Ion Gels From Side-Chain Liquid Crystalline Brushes Diblock Copolymers
The chemo-microstructure-mechanical relationships for bitumne
The analysis of the insect community present on a decomposing corpse can often provide valuable f... more The analysis of the insect community present on a decomposing corpse can often provide valuable forensic insights, especially the estimation of the time of death, or postmortem interval (PMI). Life cycle of insect act as precise clocks which starts within few minutes or hours after death. When other methods are notable to provide appropriate information, life cycle of insects plays an immense role in Postmortem interval estimation. The present results highlight the particularities of local insect fauna from human corpses from Northern India (Punjab) and its dynamics on human corpses. The insects were collected from human corpses during autopsy procedure. Out of the 5 human case studies, 4 were males and 1female; their ages ranged from 26 years to 52 years. The cause of death was either homicide or suicide. The main objective of this study was to collect necrophagous insects colonizing the human corpses as well as to gather information about their potential role in crime investigation.
Synthesis and Characterization of Polyethyleneimine-Based Lithium Conducting Polymers to be Used inEnergy Storage
Metal oxide supported Ni-impregnated bifunctional catalysts for controlling char formation and maximizing energy recovery during catalytic hydrothermal liquefaction of food waste
Sustainable Energy & Fuels, 2021
Nickel (Ni)-impregnated metal oxide catalysts, Ni/CeZrOx, Ni/ZrO2, and Ni/CeO2, were investigated... more Nickel (Ni)-impregnated metal oxide catalysts, Ni/CeZrOx, Ni/ZrO2, and Ni/CeO2, were investigated to maximize energy recovery and reduce char yield during catalytic hydrothermal liquefaction (CHTL) of food waste.
Thermal optimization of a novel thermo-optically responsive SS-PCM coatings for building enclosures
Energy and Buildings, 2021
Abstract Building energy consumption constitutes approximately 40% of total energy usage in the U... more Abstract Building energy consumption constitutes approximately 40% of total energy usage in the US. zero energy buildings (ZEBs) have received much attention in the last decade as they can alleviate some of the negative impacts that buildings have on the environment. New materials and systems are emerging that can help regulate building enclosure heat losses and gains in a passive manner, possibly leading to more cost effective ZEBs. A novel thermo-optically responsive solid-solid phase change material (SS-PCM) coating has been developed to help offset heat gains or losses in building enclosures. The study investigates the optical and thermal processes of the SS-PCM, as well as the synergies among different layers within the enclosure system, through a series of numerical simulations. The impacts of the solar incoming angle and phase transition temperature on the absorptivity of the SS-PCM, which have a significant influence on the optical and thermal transfer processes, are explored. The feasibility and benefits of using the SS-PCM system in building enclosures under both warm and cold climates are investigated. Simulation results: (1) confirm the potential of the SS-PCM coatings to reduce undesirable heat exchange through building enclosure in all orientations and identify the roof as the preferred location of installing the SS-PCM system; (2) substantiate the thermal benefits of the system throughout the year and determine the optimal phase transition temperature of the SS-PCM with maximal energy saving; and (3) demonstrate more thermal benefits and energy saving of the SS-PCM coatings in warm climates compared to cold climates, which has been a challenge for most of existing passive solar facades.
Thermo-optically responsive polymeric solid-solid phase change materials as a passive thermoregulator
Quantification of Surface Reactivity and Step-Selective Etching Chemistry on Single-Crystal BiOI(001)
Langmuir, 2020
We synthesized single-crystal BiOI(001) via vapor transport, subjected the resulting crystals to ... more We synthesized single-crystal BiOI(001) via vapor transport, subjected the resulting crystals to a series of surface treatments, and quantified the resulting chemical states and electronics. Vapor transport methods included both physical vapor transport from single-source BiOI, as well as chemical vapor transport from Bi2O3 + BiI3 and from Bi + I2 + Bi2O3. Surface treatments included tape cleaving, rinsing in water, sonication in acetone, an aqueous HF etch, and a sequential HF etch with subsequent sonication in acetone. X-ray diffraction, XRD, and X-ray photoelectron spectroscopy, XPS, probed the resulting bulk crystalline species and interfacial chemical states, respectively. In comparison with overlayer models of idealized oxide-terminated or iodide-terminated BiOI(001), angle-resolved XPS elucidated surface terminations as a function of each treatment. Ultraviolet photoelectron spectroscopy, UPS, established work-function and Fermi-level energies for each treatment. Data reveal that HF etching yields interfacial BiI3 at BiOI(001) steps that is subsequently removed with acetone sonication. UPS establishes n-type behavior for the vapor-transport-synthesized BiOI, and surface work function and Fermi level shifts for each chemical treatment under study. We discuss the implications for processing BiOI nanofilms for PV and photocatalysis applications.
Analytica Chimica Acta, 2019
Selfplasticized, lumogallion-based fluorescent optical sensor for the determination of aluminium ... more Selfplasticized, lumogallion-based fluorescent optical sensor for the determination of aluminium (III) with ultra-low detection limits, Analytica Chimica Acta,
ACS Sensors, 2019
Although IUPAC has recommended a probabilistic approach to determining limit of detection (LOD) b... more Although IUPAC has recommended a probabilistic approach to determining limit of detection (LOD) based on false positive and false negative rates for more than 20 years, the LOD definition for ion selective electrodes (ISEs) long predates these recommendations and conflicts substantively with them. Although it is well known that the ISE LOD definition does not follow best practice, it continues to be used due to simplicity and a lack of available methods for estimating LOD for non-linear sensors. Here, we use ISEs as a model system for estimation of LOD for non-linear sensors that is consistent with broad IUPAC recommendations and justified using statistical theory. Using freely available software, the new approach and updated definition is demonstrated through theory, simulation, and an environmental application. The results show that the current LOD definition for ISEs performs substantially worse than the proposed definition when assessed against IUPAC recommendations, including ignoring sensor noise and LOD uncertainty, leading to bias of an order of magnitude or more. Further, the environmental application shows that the new definition, which includes estimates of LOD uncertainty, allows more objective assessment of sensor response and fitness for purpose.
Low-Temperature Route to 1, 2-Benzoylenebenzimidazole Ladder Structure
High Performance Polymers, 1999
Low-temperature catalytic conversion of N-(o-aminophenyl)phthalamic acid (I) was studied as a mod... more Low-temperature catalytic conversion of N-(o-aminophenyl)phthalamic acid (I) was studied as a model reaction for the synthesis of ladder poly(aroylenebenzimidazole)s. The treatment of I with acetic anhydride/pyridine or trifluoroacetic anhydride resulted in the selective and quantitative cyclodehydration to yield either imide or isoimide structures respectively. The imidization was accompanied by acylation of the ortho amino group to form lateral acetamide or
Stimuli-Responsive Polymers as Active Layers for Sensors
Principles, Methods, and Applications, 2015
Proton transport through polymeric membranes XINYU WANG,
Journal of Materials Chemistry A, 2019
Microbatteries with safe, non-corrosive electrolyte chemistries can have an immediate positive im... more Microbatteries with safe, non-corrosive electrolyte chemistries can have an immediate positive impact on modern life applications, such as ingestible electronic pills and system-on-chip bioelectronics. Here a safe, non-corrosive and non-flammable...
Bitumen’s microstructures are correlated with its bulk thermal and rheological properties
Fuel, 2019
Abstract Understanding of how the chemistry of asphalt binders (i.e., bitumens) affects their bul... more Abstract Understanding of how the chemistry of asphalt binders (i.e., bitumens) affects their bulk properties is critical for development of structure-related mechanical models and performance-based specifications for asphalt binders and asphalt-related applications. However, establishing the chemical-mechanical relationships that govern asphalt binders’ properties remains a challenge due to binders’ complex chemical makeup and the intriguing molecular interactions among binders’ various chemical constituents. Here, we investigate the effect of chemical composition on binders’ microstructure, thermal, and rheological behavior. Two virgin binders (i.e., ABD and AAD) from different crude oil origins were chosen and a series of derivative binders was made by remixing different weight ratios of the asphaltenes and the maltenes obtained from the two source binders. Thermal and rheological properties of all binders were measured using modulated differential scanning calorimetry and dynamic shear rheometry, respectively. Binders’ microscopic characteristics (e.g., microstructures and their contrast in phase images) were evaluated using atomic force microscopy. Our results show that bitumens’ characteristic microstructures, as a result of the complex molecular interactions among their various chemical components, are correlated with their bulk thermal and mechanical properties. Notably, the asphaltene/maltene ratio alone cannot predict a bitumen’s bulk properties. Instead, a bitumen’s distinctive microstructures along with its colloidal index, provide meaningful insights into effect of chemical composition on glass transition, phase stability, and rheological properties of the bitumen.
Reaction kinetics of red mud-fly ash based geopolymers: Effects of curing temperature on chemical bonding, porosity, and mechanical strength
Cement and Concrete Composites, 2018
Abstract The reaction kinetics of red mud-class F fly ash based geopolymer (RFFG) was investigate... more Abstract The reaction kinetics of red mud-class F fly ash based geopolymer (RFFG) was investigated through understanding the influence of curing temperature on the formation of geopolymer gel, porosity, and the development of mechanical properties. Chemical bonding, mineralogy, mechanical properties and porosity of RFFG during a curing period of up to 120 days were assessed with Fourier transform infrared spectroscopy, X-ray diffractometer, unconfined compression tests, and micro-CT and N2-BJH techniques, respectively. The geopolymer gels were found to develop via a three-stage process: dissolution–Al-rich gels (I), Al-rich gels–Si-rich gels (II) and Si-rich gels–tectosilicate networks (III). The mechanical strength is largely governed by the development of geopolymer gels and affected by porosity, both of which are influenced by curing temperature. The early mechanical strength of RFFG is enhanced by elevated curing temperatures, but the long-term strength can be compromised by higher porosity resulted from an excessively high curing temperature.
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Papers by Sergio Granados