Amount Of Reaction Research Articles

Experimental analysis of a rotating cylinder electrode reactor: Hydrodynamics and mass transport

AbstractThis report deals with the hydrodynamic and mass transport characterization in an rotating cylinder electrode (RCE) in continuous and batch configuration employing relatively simple techniques like obtaining the mixing time, polarization, and residence time distribution (RTD) curves. For batch configuration, the limiting current and Sh values were higher than for continuous configuration, indicating that the mixing pattern is influenced by possible flow inhomogeneities during the operation as a continuous mixing stirrer. This could diminish the amount of electroactive reactant that reaches the electrode surface, due to the possible shrinking of recirculation zones during the rotation of the cylindrical stirrer, forming channeling and by‐pass flow zones. These results could evidence the existence of slight deviations from the ideal mixer and other non‐ideality flow zones associated with the width of curves upon analyzing age function through RTD curves, at the different flow rates employed in continuous configurations.

A Critical Look at the Evolution of Flow Analysis

The inception of flow analysis (FA) is closely related to the need for a better understanding of chemical reactions. At the beginning of the last century, these reactions were intensively investigated, and the main involved parameters were the reactant amounts and the available reaction time.¹ It was soon realized that solution mixing and detection were often time-dependent, so they were better accomplished on a fluidic basis.² This stimulated the development of simple flow-based instruments³ that allowed chemical reactions to be more efficiently investigated. The availability of commercial colorimetric detectors in the 1930s4 increased the demand for chemical analysis and, thus, the laboratory workload. This motivated the proposal of the AutoAnalyzer®, the first commercial air-segmented flow analyzer.5 It was intensively used for large-scale assays, persisted for several decades, and involved only a few manufacturing companies. As the implementation of official, recommended, or tentative methods was preferred, the AutoAnalyzer underwent a relatively slow evolution yet an amazing worldwide acceptance. Later on, flow analyzers without segmentation were proposed.6 An example is the flow injection analyzer, which involves precise sample insertion, controlled dispersion, and reproducible timing. Exploitation of these features improved the simplicity, versatility, and flexibility of the analyzer. Further evolution led to the emergence of the sequential injection analyzer and derived ones, which occasionally involved segmented and unsegmented streams. Nowadays, flow analysis is approaching maturity, as evidenced by the number of applications, books, book chapters, tutorials, thesis, academic courses, workshops, scientific articles, events, seminars, commercially available instruments (some of them specially designed for educational purposes), patents, etc. Intensive development of expert flow systems,7 usually exploiting manifold programming,8 is underway. Micro-flow analyzers are also being proposed, especially for large-scale assays under laboratory, in-situ and in-vivo conditions. Compliance with the principles of Green9 and White10 Analytical Chemistry has always been a positive factor for FA development. For a FA healthy evolution, inertia or setback should be avoided, and synergy rather than divergence should be ensured. To this end, flashback and consensus are relevant. Flashback permits the evaluation a particular situation in the past, whereas consensus is more related to future developments.

Statistical investigation of the experimental variables in the hydrosilylation reaction of a trimethylsiloxy‐terminated poly (methylhydro‐dimethyl)siloxane copolymer and an unsaturated polyethylene glycol using response surface methodology

The hydrosilylation reaction is a suitable route to prepare efficient, transparent, and low‐viscose silicone surfactants with low surface tension. Initial materials, the catalyst used, and experimental conditions are highly effective variables to achieve the maximum efficiency of the reaction, reduce the consumption of the catalyst, and prevent side reactions. To draw a comprehensive conclusion on the effect of these variables, a series of trimethylsiloxy‐terminated poly (methylhydro‐dimethyl)siloxanes copolymer (abbreviated as RSiH with different preceding numbers) and two unsaturated polyethylene glycols (UPEG200 and UPEG400) were selected, and the reactions in the presence of two platinum‐based catalysts, namely, hexachloroplatinic acid and ammonium hexachloroplatinate, were statistically studied by Design of Experiment. After initial pre‐investigations, the amounts of reactant and catalyst were subjected to analysis of variance using response surface methodology (RSM). Based on the results, low‐viscose and low‐surface tension silicone surfactants were obtained using UPEG400, RSiH105, and (NH4)2PtCl6 as catalysts, at temperatures over 170 °C. The best results were obtained with a relatively low concentration of the catalyst between 2.57 × 10−6 and 2.72 × 10−6 equivalent catalyst per UPEG. The relative equivalent ratio of [UPEG]/[RSiH] at the optimum condition was 1.6, which provided a surface tension below 21 mN/m together with a minimum amount of unreacted RSiH (less than 3%). The silicone surfactant was characterized as a pure product by a series of spectroscopic methods, such as FT‐IR and 1H NMR spectroscopies, as well as bromine number index. These excellent properties make this compound a new alternative in various industries.

Complex Droplet Microreactor for Highly Efficient and Controllable Esterification and Cascade Reactions.

A highly efficient complex emulsion microreactor has been successfully developed for multiphasic water-labile reactions, providing a powerful platform for atom economy and spatiotemporal control of reaction kinetics. Complex emulsions, composing a hydrocarbon phase (H) and a fluorocarbon phase (F) dispersed in an aqueous phase (W), are fabricated in batch scale with precisely controlled droplet morphologies. A biphasic esterification reaction between 2-bromo-1,2-diphenylethane-1-ol (BPO) and perfluoro-heptanoic acid (PFHA) is chosen as a reversible and water-labile reaction model. The conversion reaches up to 100 % under mild temperature without agitation, even with nearly equivalent amounts of reactants. This efficiency surpasses all reported single emulsion microreactors, i. e., 84~95 %, stabilized by various emulsifiers with different catalysts, which typically necessitate continuous stirring, a high excess of one reactant, and/or extended reaction time. Furthermore, over 3 times regulation threshold in conversion rate is attained by manipulating the droplet morphologies, including size and topology, e. g., transition from completely engulfed F/H/W double to partially engulfed (F+H)/W Janus. Addition-esterification, serving as a model for triple phasic cascade reaction, is also successfully implemented under agitating-free and mild temperature with controlled reaction kinetics, demonstrating the versatility and effectiveness of the complex emulsion microreactor.

Silane Gas Production Through Hydrolysis of Magnesium Silicide by Hydrochloric Acid

Monosilane (SiH4) is a common precursor for the production of high-purity silicon for solar PV applications. As an alternative to carbothermic reduction of silica to produce metallurgical grade silicon with subsequent conversion to silane, an alternative route over magnesiothermic reduction of silica to Mg2Si has been explored in our earlier work. In the current work, silane gas production through hydrolysis of Mg2Si in HCl acid solution was studied. Two sources of Mg2Si were chosen: a commercial Mg2Si source and a Mg2Si source produced through magnesiothermic reduction of high-purity natural quartz. Effects of various parameters on the hydrolysis of Mg2Si, including different experimental setups, temperature of the acid solution, acid concentration, reaction time, and relative amounts of reactants were studied. The evolution of produced gases was determined by two different methods: firstly, by passing the produced gas through a KOH solution to capture Si with subsequent analysis of the Si content in the KOH solution by inductively coupled plasma mass spectrometry and secondly, on-line gas analysis by GC–MS. The silane distribution between different silane species with reaction time was evaluated and the activation energy of silane formation was calculated. The results indicated comparable silane yields obtained from the on-line GC–MS method and KOH solution analysis method, as well as for commercial Mg2Si and the Mg2Si–MgO mixture produced through magnesiothermic reduction. Furthermore, adding HCl acid to Mg2Si in water led to higher SiH4 formation yield than adding Mg2Si to acid. However, the total silane yield for the two methods was similar at approximately 32%.Graphical

An efficient process for preparing regenerated magnets by dynamic recovery of Nd-Fe-B sintered magnet sludge

As a new technology for the short-process recovery of Nd–Fe–B sintered magnet sludge, the calcium thermal reduction diffusion method has attracted significant attention due to its low energy consumption, environmental friendliness, and high recovery rate. However, traditional calcium thermal reduction diffusion technology still has issues such as an insufficient reaction between the sludge and reducing agent after increasing the amount of reactants, the use of a large amount of reducing agent, and low recovery efficiency. Therefore, a novel dynamic calcium thermal reduction diffusion technology was proposed, with the calcium reduction diffusion of sludge and calcium undergoing a continuous mixing and diffusion state throughout the entire process, greatly improving the efficiency of the reaction. Compared with the traditional process, the amount of reactants was increased from a few grams to hundreds of grams, and the amount of reducing agent calcium was reduced by 25%. Subsequently, regenerated magnetic powder with a uniform particle size, good dispersion, and excellent magnetic properties was obtained. The saturation magnetization under a 3 T magnetic field was increased by 27.9% compared with the initial sludge. The maximum magnetic energy product of the magnet prepared by doping 50 wt% regenerated magnetic powder was 45 MGOe, which reached the highest level of the regenerated magnets prepared by recycling sludge. What is encouraging that this new technology had the advantage of achieving large-scale production and reducing production costs, providing a potential industrialization solution for the green and efficient recovery of Nd–Fe–B sintered magnet sludge.

Efficient Synthesis and HPLC-Based Characterization for Developing Vanadium-48-Labeled Vanadyl Acetylacetonate as a Novel Cancer Radiotracer for PET Imaging.

Bis(acetylacetonato)oxidovanadium(IV) [(VO(acac)2], generally known as vanadyl acetylacetonate, has been shown to be preferentially sequestered in malignant tissue. Vanadium-48 (48V) generated with a compact medical cyclotron has been used to label VO(acac)2 as a potential radiotracer in positron emission tomography (PET) imaging for the detection of cancer, but requires lengthy synthesis. Current literature protocols for the characterization of VO(acac)2 require macroscale quantities of reactants and solvents to identify products by color and to enable crystallization that are not readily adaptable to the needs of radiotracer synthesis. We present an improved method to produce vanadium-48-labeled VO(acac)2, [48V]VO(acac)2, and characterize it using high-performance liquid chromatography (HPLC) with radiation detection in combination with UV detection. The approach is suitable for radiotracer-level quantities of material. These methods are readily applicable for production of [48V]VO(acac)2. Preliminary results of preclinical, small-animal PET studies are presented.

Precision of Radiation Chemistry Networks: Playing Jenga with Kinetic Models for Liquid-Phase Electron Microscopy.

Liquid-phase transmission electron microscopy (LP-TEM) is a powerful tool to gain unique insights into dynamics at the nanoscale. The electron probe, however, can induce significant beam effects that often alter observed phenomena such as radiolysis of the aqueous phase. The magnitude of beam-induced radiolysis can be assessed by means of radiation chemistry simulations potentially enabling quantitative application of LP-TEM. Unfortunately, the computational cost of these simulations scales with the amount of reactants regarded. To minimize the computational cost, while maintaining accurate predictions, we optimize the parameter space for the solution chemistry of aqueous systems in general and for diluted HAuCl4 solutions in particular. Our results indicate that sparsened kinetic models can accurately describe steady-state formation during LP-TEM and provide a handy prerequisite for efficient multidimensional modeling. We emphasize that the demonstrated workflow can be easily generalized to any kinetic model involving multiple reaction pathways.

Competitive Specific Anchorage of Molecules onto Surfaces: Quantitative Control of Grafting Densities and Contamination by Free Anchors.

The formation of surfaces decorated with biomacromolecules such as proteins, glycans, or nucleic acids with well-controlled orientations and densities is of critical importance for the design of in vitro models, e.g., synthetic cell membranes and interaction assays. To this effect, ligand molecules are often functionalized with an anchor that specifically binds to a surface with a high density of binding sites, providing control over the presentation of the molecules. Here, we present a method to robustly and quantitatively control the surface density of one or several types of anchor-bearing molecules by tuning the relative concentrations of target molecules and free anchors in the incubation solution. We provide a theoretical background that relates incubation concentrations to the final surface density of the molecules of interest and present effective guidelines toward optimizing incubation conditions for the quantitative control of surface densities. Focusing on the biotin anchor, a commonly used anchor for interaction studies, as a salient example, we experimentally demonstrate surface density control over a wide range of densities and target molecule sizes. Conversely, we show how the method can be adapted to quality control the purity of end-grafted biopolymers such as biotinylated glycosaminoglycans by quantifying the amount of residual free biotin reactant in the sample solution.

Enhancing biodiesel production from urban sewage sludge: A novel industrial configuration and optimization model

In this work, a novel industrial configuration for the lipid extraction from sewage sludge was proposed. In detail, respect to conventional scheme based on direct extraction of lipids from wet sedimented sewage sludge using hexane, a preliminary centrifugation of sewage sludge prior to the extraction process was introduced. Economic and energetic balances for both configurations were evaluated using Aspen Plus simulator, including the post-treatment of exhausted sewage sludge obtained after the process. By centrifuging sewage sludge prior to the extraction process, overall costs can be reduced (27 % less), while preserving the same extraction efficiency for lipid recovery (80 %). Initial capital investments, amounts of reactants and total energy demand were sensibly reduced to achieve BEP of extracted lipids of 784 € ton-1 (vs 1.291 € ton-1 for conventional route). Finally, the economic feasibility of biodiesel production from lipids obtained from centrifuged sludge was evaluated by applying direct esterification with methanol and AlCl3·6H2O BEP of biodiesel produced of 1.186 € ton-1 was obtained with NPV of 27.5 M€ and DPP of 2.5 years. These values, show that biodiesel production from sewage sludge could be profitable considering only the proposed approach, fully unlocking the potential of waste in coherence with circular economy principles.

Interface and magnetic-dielectric synergy strategy to develop Fe3O4-Fe2CO3/multi-walled carbon nanotubes/reduced graphene oxide mixed-dimensional multicomponent nanocomposites for microwave absorption

Interfacial and/or magnetic-dielectric synergistic effects are important avenues to boost microwave absorption properties. In order to simultaneously utilize these effects, we elaborately designed mixed-dimensional Fe3O4-FeCO3/multi-walled carbon nanotubes (MWCNTs)/reduced graphene oxide (RGO) multicomponent nanocomposites (MCNCs) in large scale via a facile process of hydrothermal and freeze-drying. The microstructural investigation revealed that two-dimensional RGO, one-dimensional MWCNTs and zero-dimensional Fe3O4-FeCO3 nanoparticles were well bounded to generate the typical mixed-dimensional structure. By controlling the amounts of initial reactants, the Fe3O4-FeCO3/MWCNTs/RGO MCNCs displayed improved impedance matching features, polarization and conduction loss abilities, which lead to the evidently improved electromagnetic absorption properties. The Fe3O4-FeCO3/MWCNTs/RGO MCNCs simultaneously exhibited excellent absorption ability, large absorption bandwidth, low density and thin matching thickness. Generally, this work not only proposed an effective route to make the best of magnetic-dielectric synergy and interfacial strategy for exploiting novel microwave absorption materials, but also presented a simple approach to synthesize magnetic MWCNTs/RGO-based mixed-dimensional MCNCs.

Mitigation of arsenic and fluoride from water via porous polymeric network knitted with zirconium moiety in three-dimensional shape: Experimental and mathematical modeling investigation

The presence of toxic contaminants in water seriously threatens human health. Thus, in order to address the water pollution through toxic contaminants, a new type of cross-linked porous polymeric microsphere namely; poly(Zirconyl dimethacrylate) (pZrDMA), was successfully prepared by a single-step facile approach. The pZrDMA comprises an acrylate chain of zirconium moiety, which is a proficient adsorbent for arsenic and fluoride remediation. A series of pZrDMA were prepared by varying the relative amounts of reactants to get an appropriate composition. The pZrDMA having, a high surface area (SA: 392.12 m2 g−1) and porosity (Pore size: 0.93–2.36 µm), has exhibited maximum adsorption capacities (qe) of 4.26 mg g−1, 4.22 mg g−1 and 198.5 mg g−1 As(V), As(III) and F− respectively. The pZrDMA displayed high removal efficiency (>97 %) for all the ions over a wide pH range (2.0 ± 0.2 to 10 ± 0.2). The adsorption kinetic and isotherms are well described by the pseudo-second-order model (PSO), and Langmuir isotherm model for both toxic ions arsenic and fluoride. The multicomponent adsorption isotherm with arsenic and fluoride has also studied. The experimental data analysis using the ANN model provides a high accuracy of the model with larger correlation coefficient values (R > 0.99). The pore diffusion modeling predicted the breakthrough time of 174 h, 1542 h, and 1466 h for F−, As(V), and As (III), respectively.

Investigation of the decomposition mechanism of MTNP melt-cast explosive at different temperatures and pressures through ReaxFF/lg molecular dynamics simulations.

Thermal decomposition of 1-methyl-3,4,5-trinitropyrazole (MTNP), a melt-cast explosive, was investigated at different temperatures (2500, 2750, 3000, 3250, and 3500 K) and pressures (3000 K/0.5 GPa, 3000 K/1 GPa) using the ReaxFF/lg force field. The study aimed to analyze the changes in reactant quantities, initial reaction pathways, and final product yields. The results demonstrated that complete decomposition of MTNP molecules occurred within a timeframe of 200 ps, with shorter decomposition times observed as the temperature increased. The high-temperature thermal decomposition of MTNP was found to follow two primary reaction pathways. Reaction 1 involved denitration, while reaction 2 proceeded with nitro group isomerization. DFT calculations indicated that nitro group isomerization was the most favorable reaction. During the initial stages, higher quantities of NO2, NO, and N2 were observed compared to other species. This can be attributed to the relatively higher nitrogen and oxygen content in the MTNP structure. Among the five reaction temperatures, it was observed that the quantities of small molecules followed the order of NO2 > NO > N2 > CO. Moreover, with increasing temperature, the quantities of all four small molecules increased, indicating that higher temperatures promoted the progression of the reactions. However, as the pressure increased, there was a trend of initially increasing and then decreasing to zero for the quantities of NO2 and NO. This suggests that high temperature accelerated the high-temperature thermal decomposition of NO2 and NO, leading to a significant increase in the content of N2. A 3 × 5 × 5 supercell model of MTNP was constructed in Materials Studio, consisting of 75 unit cells and 300 MTNP molecules. The model was then subjected to a 20 ps geometric optimization using the Polak-Ribiere version of the conjugate gradient (CG) algorithm in the large-scale atomic/molecular massively parallel simulator (LAMMPS) under the isothermal-isobaric (NPT) ensemble at 1 atm pressure and 300 K temperature. Following the optimization, molecular dynamics simulations were performed on the model at five temperatures (2500, 2750, 3000, 3200, and 3500 K) under 1 atm using the NPT ensemble for a total duration of 1 ns. During the simulations, atomic trajectories, as well as information on atomic and molecular species, were output every 500 steps. Subsequently, a custom script was utilized to analyze the thermal decomposition pathways and products. A time step of 0.1 fs was employed for the calculations, and periodic boundary conditions were applied to eliminate boundary effects.

Research of the workability, mechanical and hydration mechanism of coal gangue-construction solid waste backfilling materials

In order to effectively address the issues of coal gangue emissions and the accumulation of construction solid waste, a combined treatment of coal gangue and construction solid waste can be implemented. In this study, a composite backfilling material was designed, with coal gangue and construction solid waste as the main aggregates. Through laboratory experiments, the time-dependent flow performance, mechanical properties, and microstructure of the material were analyzed under different proportions of factors including fly ash content, substitution rate of construction solid waste, mass concentration, and water reducing agent content. The research results indicate the following: The effects of reducing agent content, mass concentration, fly ash content, and substitution rate of construction solid waste on flow performance increased in that order. The addition of construction solid waste is negatively correlated with the strength of filling materials. The appropriate substitution ratios for FA, construction solid waste, mass concentration, and reducing agent were determined to be 21 %, 50 %, 80 %, and 0.6 %, respectively. The CH component in the material exhibited a trend of initially increasing and then decreasing, providing a large amount of reactants for secondary hydration reactions and strengthening the internal structure of the material. In the middle stage of hydration, FA and activators played an important role in the later stage by providing raw materials for secondary hydration, enriching the internal composition of the structure, and enhancing the backfilling performance of the backfilling material. This study can achieve the recycling and utilization of coal gangue and construction solid waste, and enhance the stability and bearing capacity of backfilling materials.

Hyporheic exchange and nitrogen cycle processes under the dual effects of flooding and heterogeneous streambed

In this study, we investigated the effects of media heterogeneity and flood processes on hyporheic exchange and nitrogen cycle processes in hyporheic zone adjacent to a natural in-stream gravel bar. We conducted field experiments and set a reactive transport model of surface-groundwater exchange based on the monitoring results. The flood process is obtained based on field monitoring, and the heterogeneous medium field is constructed using the SAR3DC method based on in-site experiment results. The results showed that both the heterogeneity of the medium and the flood process can enhance the spatial variability of velocity distribution, resulting in an increase of exchange flux, a decrease in lag time, and an extension of the migration path. For heterogeneous media, it is easier to form specific channels for high velocity flow, and the flow velocity within them is more sensitive to changes in media and hydrodynamic conditions, the direction of hyporheic exchange can be reversed in some specific channels. For the nitrogen cycle processes, the heterogeneous medium condition determines the source-sink functions and the direction of nitrate nitrogen reduction in hyporheic zone by providing a wider reaction space for reactants, reducing the lag time to 1/40 and increasing the migration path by 4 times. The flood process can increase the infiltration amounts of reactants by 5 times and reduce the lag time (time of particle entry into the hyporheic zone to migrate out) to 1/6. In general, under the effects of media heterogeneity and flood processes, the reaction rates and nitrate nitrogen reduction rates during the nitrogen cycle processes are decreasing and the hyporheic zone will face greater pollution risks.

Quantitative study of the adsorption sites and reaction mechanism of NH3-SCR on Cu-SSZ-39 and H-SSZ-39

Cu-SSZ-39 demonstrated exceptional resistance to hydrothermal aging during NH3-SCR. So far, the precise quantification of adsorption sites for various reactants on Cu-SSZ-39 remains uncertain. In this study, the quantitative analysis using a transient response method (TRM) allowed for determining the adsorption quantities of reactants, as well as the concentrations of various Cu species, and the reaction pathway on Cu-SSZ-39 and H-SSZ-39. Cu benefited N2 formation through NO reacting with adsorbed NH3, while NH4NO3 reacted with NO to form N2 instead of NO2 or N2O. On Cu-SSZ-39, the dominant pathway involved NO reacting with adsorbed NH3, resulting in the production of N2 and H2O, and another important pathway was “NH4NO3 fast path” (NH4NO3 + NO + *-ONH4 + * → 2 N2 + 3 H2O + 2 *-OH). O2 facilitated the reaction between NO and NH3. The numbers of Z2Cu2+and ZCu-OH were also determined by TRM. More Z2Cu2+ species caused its high hydrothermal stability.

Reactant enrichment in hollow void of Pt NPs@MnOx nanoreactors for boosting hydrogenation performance.

In confined mesoscopic spaces, the unraveling of a catalytic mechanism with complex mass transfer and adsorption processes such as reactant enrichment is a great challenge. In this study, a hollow nanoarchitecture of MnOx-encapsulated Pt nanoparticles was designed as a nanoreactor to investigate the reactant enrichment in a mesoscopic hollow void. By employing advanced characterization techniques, we found that the reactant-enrichment behavior is derived from directional diffusion of the reactant driven through the local concentration gradient and this increased the amount of reactant. Combining experimental results with density functional theory calculations, the superior cinnamyl alcohol (COL) selectivity originates from the selective adsorption of cinnamaldehyde (CAL) and the rapid formation and desorption of COL in the MnOx shell. The superb performance of 95% CAL conversion and 95% COL selectivity is obtained at only 0.5MPa H2 and 40min. Our findings showcase that a rationally designed nanoreactor could boost catalytic performance in chemoselective hydrogenation, which can be of great aid and potential in various application scenarios.

Synthesis of nucleus-satellite like Ag nanoparticles based on dielectric barrier discharge system for prolonged chemiluminescence imaging of mercury ions

Noble metal nanomaterials were unique in the field of chemiluminescence (CL) because of their high catalytic activity and surface plasmon resonance (SPR). Herein, polyhedral oligomeric silsesquioxanes modified silver nanoparticles (POSS-Ag NPs) were firstly synthesized by dielectric barrier discharge system within 40 min. Amino modified POSS (AE-POSS), as both a reducing agent and protective agent, was bonded to the surface of Ag NPs to stabilized Ag NPs through the three-dimensional framework structure to form “nucleus-satellite” like structures, which specially showed enhanced CL intensity due to increased specific surface area and SPR characteristics. Subsequently, a prolonged CL signal for over 1 h by POSS-Ag NPs - luminol system happened, which could be well observed in the CL imaging. The presence of Ag0/Ag+ and O2/·O2– charge cycling transfer on the surface of POSS-Ag NPs continuously provided large amounts of catalysts (Ag0) and CL reactants (Ag+), continuously reacting with luminol to greatly prolong the CL reaction time. Significantly, due to the mercury (Hg)-Ag alloys production in Ag NPs solution to inhibit catalytic and SPR effects, this intense and long-time CL system for the specific imaging detection of Hg2+ was developed. The detection limit of this method was 3 × 10−8 M. The enhanced prolonged CL phenomenon could improve the accuracy of chemical analysis and have promising applications in CL imaging.

Statistical analysis of randomized pseudo-first/second order kinetic models. Application to study the adsorption on cadmium ions onto tree fern

Adsorption kinetics are commonly modeled using pseudo-first order (PFO) and pseudo-second order (PSO) rate laws. Both models are formulated via differential equations whose coefficients are commonly treated as deterministic quantities, which are calculated from experimental data using regression techniques. In this paper, we propose a full randomization of both models by assuming that all the parameters of the PFO and PSO models are random variables with arbitrary densities. Then, we probabilistically solve both models by determining semi-explicit expressions of the first probability density functions of the corresponding solution stochastic processes, as well as the densities of the time until a fixed adsorbed amount of reactant has been reached for each model too. The analysis is conducted under very general assumptions and is based on extensive application of the so-called Random Variable Transformation (RVT) technique. Finally, we apply all the aforementioned theoretical findings to model the adsorption of cadmium ions onto tree fern, using real data. We compare the results obtained by the randomized PFO and PSO models, using a Bayesian and a randomized version of the least mean square method to assign reasonable densities to model parameters. After comparing the results, the PSO model is selected, and, we then show how the RVT technique can be applied to obtain further key information, such as the second probability density function, of the solution and the covariance function.

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1–1000 μm), using small amounts of samples and reactants, ca. 102–103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.