Multifactor Uncertain Chemical Reaction Equation

The previous uncertain chemical reaction equation describes the time evolution of single reactions. But in many practical cases, a substance is consumed by several different reaction pathways. For the above considerations, this paper extends the discussion to multiple reactions. Specifically, by taking the decomposition of C2H5OH as an example, parallel reactions with one reactant are analyzed with the multifactor uncertain differential equation. The derived equation is called the multifactor uncertain chemical reaction equation. Following that, the parameters in the multifactor uncertain chemical reaction equation are estimated by the generalized moment estimation. Based on the multifactor uncertain chemical reaction equation, half-life of reaction is investigated. Finally, a numerical example is presented to illustrate the usefulness of the multifactor uncertain chemical reaction equation.

Shifts in Spiritual and Religious Self-Perceptions in the First Year of College

This study draws on an original national and longitudinal survey to examine patterns and predictors of change in religious and spiritual self-perceptions among over seven thousand college students in their first year on campus. The chapter identifies the personal characteristics, institutional contexts, and collegiate experiences that shaped students’ perceptions of themselves in relation to religion and spirituality. Twenty-eight percent of first-year students changed their self-perception in the first year of college; a switch to “spiritual but not religious” was the most common type of change. The study illuminates parallel reactions to religious and spiritual descriptors among certain groups. For example, both atheists and evangelical Christians were less likely than mainline Protestants to adopt the “religious but not spiritual” and “spiritual but not religious” labels. Lived experiences in the first year of college made a notable impact on students’ self-perceptions of spirituality.

Antioxidative Reactivity of L-Ascorbic Acid and D-Isoascorbic Acid Species towards Reduction of Hexachloroiridate (IV)

The pair [IrCl6]2–/[IrCl6]3– has been demonstrated to be a good redox probe in biological systems while L-ascorbic acid (AA) is one of the most important antioxidants. D-isoascorbic acid (IAA) is an epimer of AA and is widely used as an antioxidant in various foods, beverages, meat, and fisher products. Reductions of [IrCl6]2– by AA and IAA have been analyzed kinetically and mechanistically in this work. The reductions strictly follow overall second-order kinetics and the observed second-order rate constants were collected in the pH region of 0 ≤ pH ≤ 2.33 at 25.0°C. Spectrophotometric titration experiments revealed a well-defined 1 : 2 stoichiometry, namely Δ[AA] : Δ[Ir(IV)] or Δ[IAA] : Δ[Ir(IV)] = 1 : 2, indicating that L-dehydroascorbic acid (DHA) and D-dehydroisoascorbic acid (DHIA) were the oxidation products of AA and IAA, respectively. A reaction mechanism is suggested involving parallel reactions of [IrCl6]2– with three protolysis species of AA/IAA (fully protonated, monoanionic, and dianionic forms) as the rate-determining steps and formation of ascorbic/isoascorbic and ascorbate/isoascorbate radicals; in each of the steps, [IrCl6]2– acquires an electron via an outer-sphere electron transfer mode. Rate constants of the rate-determining steps have been derived or estimated. The fully protonated forms of AA and IAA display virtually identical reactivity whereas ascorbate and isoascorbate monoanions have a significant reactivity difference. The ascorbate and isoascorbate dianions are extremely reactive and their reactions with [IrCl6]2– proceed with the diffusion-controlled rate. The species versus pH and the species reactivity versus pH distribution diagrams were constructed endowing that the ascorbate/isoascorbate monoanionic form dominated the total reactivity at physiological pH. In addition, the value of pKa1 = 3.74 ± 0.05 for IAA at 25.0°C and 1.0 M ionic strength was determined in this work.

Reactor Selection for Upgrading Hemicelluloses: Conventional and Miniaturised Reactors for Hydrogenations

This work presents an advanced reactor selection strategy that combines elements of a knowledge-based expert system to reduce the number of feasible reactor configurations with elaborated and automatised process simulations to identify reactor performance parameters. Special focus was given to identify optimal catalyst loadings and favourable conditions for each configuration to enable a fair comparison. The workflow was exemplarily illustrated for the Ru/C-catalysed hydrogenation of arabinose and galactose to the corresponding sugar alcohols. The simulations were performed by using pseudo-2D reactor models implemented in Aspen Custom Modeler® and automatised by using the MS-Excel interface and VBA. The minichannel packings, namely wall-coated minichannel reactor (MCWR), minichannel reactor packed with catalytic particles (MCPR), and minichannel reactor packed with a catalytic open-celled foam (MCFR), outperform the conventional and miniaturised trickle-bed reactors (TBR and MTBR) in terms of space-time yield and catalyst use. However, longer reactor lengths are required to achieve 99% conversion of the sugars in MCWR and MCPR. Considering further technical challenges such as liquid distribution, packing the reactor, as well as the robustness and manufacture of catalysts in a biorefinery environment, miniaturised trickle beds are the most favourable design for a production scenario of galactitol. However, the minichannel configurations will be more advantageous for reaction systems involving consecutive and parallel reactions and highly exothermic systems.

Insight into Platinum Poisoning Effect on Cu-SSZ-13 in Selective Catalytic Reduction of NOx with NH3

Platinum’s (Pt) poisoning effect on Cu-SSZ-13 and its regeneration were investigated. The Pt enhanced the parallel reactions, such as NH3 oxidation and NO oxidation reactions, which decreased the deNOx activities. In the temperature range below 330 °C, the deactivation of Cu-SSZ-13 by Pt poisoning was primarily caused by the overconsumption of NH3, due to the enhanced NH3-selective oxidation reaction, while the formation of NOx in NH3 oxidation and NO oxidation into NO2 further aggravated the degradation when the temperature was above 460 °C. The non-selective NH3 oxidation and non-selective NOx catalytic reduction reactions resulted in increased N2O formation over Pt-doped samples. The transformation of Pt0 into PtOx after hydrothermal aging recovered the deNOx activities of the Pt-poisoned samples.

Kinetics of the Cationic bio-reduction involved in the biosynthesis of silver nanoparticles from Leea Coccinea Leaves

The resistance of microorganisms to conventional antimicrobials is one of the most serious health problems that affect not only the human, but also animals and plants, making the search for antimicrobial active ingredients a priority of global research. Green synthesis of antimicrobial silver nanoparticles (AgNPs) is a simple, cost-effective, rapid, reproducible, and environment friendly alternative for which numerous plant species have been reported for this purpose. Previous studies have shown the potential of Leea coccinea leaves in to the biosynthesis of antimicrobial silver nanoparticles. The current research aimed to study the kinetics of the reaction of synthesis of AgNPs by cationic bio-reduction from this botanical bioresource. A technology for the synthesis of AgNPs was established and the influence of operational parameters such as the bio-reduction conditions and the kinetics of the reaction were studied. AgNPs were characterized at different times by UV-VIS spectroscopic method, scanning electron microscopy, determination of particle size, and Z potential through Dynamic Light Scattering technique (DLS). Addition of tensoactive substances was evaluated for the stabilization of the suspension of nanoparticles. The results showed that spherical AgNPs smaller than 100 nm were obtained, which were visually identified by the formation of a dark brown complex with maximum absorption at 470 nm. Kinetic studies demonstrated the influence of the initial plant material on speed and performance, making evident a complex phenomenology with the possible occurrence of parallel reactions, which points to the possible reaction of different reducing compounds contained in this natural source. Addition of surface agents, such as SDS (0,5 %) or maltose (0,5 %), improved the stabilization in the aqueous medium, suggesting the continuation of studies to develop pharmaceuticals formulations based on AgNPs.

Dry Reforming of Methane over Carbon Fibre-Supported CeZrO2, Ni-CeZrO2, Pt-CeZrO2 and Pt-Ni-CeZrO2 Catalysts

Dry reforming of methane (DRM) is one of the most important processes allowing transformation of two most potent greenhouse gases into a synthesis gas. The CH4 and CO2 are converted at high temperatures in the presence of a metal catalyst (usually Ni, also promoted with noble metals, supported over various oxides). The DRM process is not widely used in the gas processing industry because of prompt deactivation of the catalyst owing to carbon deposition and the blockage of the metal active sites. This problem can be hindered by proper design of the catalyst in terms, e.g., of its composition and by providing strong interaction between active metal and catalytic support. The properties of the latter are also crucial for the catalyst’s performance in DRM and the occurrence of parallel reactions such as reverse water gas shift, CO2 deoxidation or carbon formation. In this paper we show for the first time the DRM performance of the ceria-zirconia and metal (Ni and/or Pt) supported on carbon fibres. The obtained Ni and Ni-Pt containing catalysts showed relatively high activity in the studied reaction and high resistance towards carbon deposition.

Repurposing Inflatable Packaging Pillows as Bioreactors: a Convenient Synthesis of Glucosone by Whole-Cell Catalysis Under Oxygen

Biocatalysis using molecular oxygen as the electron acceptor has significant potential for selective oxidations at low cost. However, oxygen is poorly soluble in water, and its slow rate of mass transfer in the aqueous phase is a major obstacle, even for laboratory-scale syntheses. Oxygen transfer can be accelerated by vigorous mechanical methods, but these are often incompatible with biological catalysts. Gentler conditions can be achieved with shallow, high surface area bag reactors that are designed for single use and generally for specialized cell culture applications. As a less-expensive alternative to these high-end bioreactors, we describe repurposing inflatable shipping pillows with resealable valves to provide high surface area mixing under oxygen for preparative synthesis of glucosone (D-arabino-hexos-2-ulose) from D-glucose using non-growing Escherichia coli whole cells containing recombinant pyranose 2-oxidase (POX) as catalyst. Parallel reactions permitted systematic study of the effects of headspace composition (i.e., air vs 100% oxygen), cell density, exogenous catalase, and reaction volume in the oxidation of 10% glucose. Importantly, only a single charge of 100% oxygen is required for stoichiometric conversion on a multi-gram scale in 18 h with resting cells, and the conversion was successfully repeated with recycled cells.

Lewis Acid-Facilitated Radiofluorination of MN3PU: A LRRK2 Radiotracer

Background: Temperature-sensitive radiopharmaceutical precursors require lower reaction temperatures (<100 °C) during nucleophilic radiofluorination in order to avoid compound thermolysis, often resulting in sub-optimal radiochemical yields (RCYs). To facilitate nucleophilic aromatic substitution (SNAr) of nucleofuges commonly used in radiofluorination (e.g., nitro group), we explored the use of Lewis acids as nucleophilic activators to accelerate [18F]fluoride incorporation at lower temperatures, and thereby increasing RCYs for thermolabile activated precursors. Lewis acid-assisted radiofluorination was exemplified on the temperature-sensitive compound 1-(4-(4-morpholino-7-neopentyl-7H-pyrrolo[2,3-d]pyrimidin-2-yl)phenyl)-3-(6-nitropyridin-3-yl)urea (MN3PU, compound 3) targeting leucine-rich repeat kinase 2 (LRRK2), an important target in the study of Parkinson’s disease and various cancers. Methods: To a vessel containing dried K[18F]F-K222 complex, a solution of precursor MN3PU ((3), 1 mg; 1.8 μmol) and Lewis acid (6 μL of 0.2 μmol: chromium II chloride (A), ferric nitrite (B) or titanocene dichloride (C)) in 500 μL of N,N-dimethylformamide (DMF) (with 10% t-BuOH for B) were added. Reactions were stirred for 25 min at 90 °C. In parallel, reactions were conducted without the addition of Lewis acids for baseline comparison. After purification via preconditioned Sep-Pak C18 plus cartridges, aliquots were analyzed by analytical radio-HPLC. Results: Non-decay corrected radiochemical yields (ndc RCYs) for [18F]FMN3PU (7) were improved from 1.7 ± 0.7% (no addition of Lewis acids) to 41 ± 1% using Cr(II) and 37 ± 0.7% using Ti(II)-based Lewis acids, with radiochemical purities of ≥96% and molar activities (Am) of up to 3.23 ± 1.7 Ci/μmol (120 ± 1.7 GBq/μmol). Conclusion: RCYs of [18F]FMN3PU (7) improved from ~5% using conventional nucleophilic radiofluorination, up to 41 ± 1% using Lewis-acid supported SNAr.