Concentration Of Sites Research Articles

Analysing the suitability of CaTiO3/Ca1–xSrxTiO3/SrTiO3 perovskite for fabrication of optoelectronic devices using QuantumATK tool: a study for electronic and optical properties

Calcium Titanate (CaTiO3) as a material has been researched for various applications like those in capacitors, piezoelectric devices and ceramic applications. Same has been possible owing to the exhibition of various characteristics of this material like high melting point (1,625 °C) and dielectric properties. However, only limited studies have been conducted to understand the impact of Strontium (Sr) doping and possibility of adopting this material into any kind of optoelectronic applications. This paper carries on an in-depth analysis on CaTiO3 and study effect of Sr as a dopant on its properties. Analysis has been carried out using Quantum ATK tool based on DFT approximations. CaTiO3 perovskite properties were studied by using the GGA (Generalized Gradient Approximation) and PBE (Perdew–Burke–Ernzerhof) functionals, which are used with the LCAO calculator. As a result of the inclusion of Sr at the Ca site, the electronic band structure of CaTiO3 was changed by the introduction of a gamma point. Bandgap of CaTiO3 was analysed to be dependent on the Sr site concentration and increased from 2.3 eV (Direct bandgap) to 2.3612 eV (Indirect bandgap), when Sr and Ca site concentration were equal, but it decreased with further increase in Sr site concentration to 1.7155 eV. Pure CaTiO3’s projected density of states changed after doping, providing evidence for the effects of the dopant on the system. As a result of an examination of the optical properties of both systems, it is found that CaTiO3 at 380 nm (close to infrared) exhibits an effective extinction coefficient (k) value of 0.78, whereas at 600 nm, the attenuation of light decreases to zero. This makes Sr doping in CaTiO3 another attractive candidate for optical devices in addition to its ability to change optical properties.

In Silico Acute Aquatic Hazard Assessment and Prioritization Using a Grouped Target Site Model: A Case Study of Organic Substances Reported in Permian Basin Hydraulic Fracturing Operations.

Hydraulic fracturing (HF) is commonly used to enhance onshore recovery of oil and gas during production. This process involves the use of a variety of chemicals to support the physical extraction of oil and gas, maintain appropriate conditions downhole (e.g., redox conditions, pH), and limit microbial growth. The diversity of chemicals used in HF presents a significant challenge for risk assessment. The objective of the present study is to establish a transparent, reproducible procedure for estimating 5th percentile acute aquatic hazard concentrations (e.g., acute hazard concentration 5th percentiles [HC5s]) for these substances and validating against existing toxicity data. A simplified, grouped target site model (gTSM) was developed using a database (n = 1696) of diverse compounds with known mode of action (MoA) information. Statistical significance testing was employed to reduce model complexity by combining 11 discrete MoAs into three general hazard groups. The new model was trained and validated using an 80:20 allocation of the experimental database. The gTSM predicts toxicity using a combination of target site water partition coefficients and hazard group-based critical target site concentrations. Model performance was comparable to the original TSM using 40% fewer parameters. Model predictions were judged to be sufficiently reliable and the gTSM was further used to prioritize a subset of reported Permian Basin HF substances for risk evaluation. The gTSM was applied to predict hazard groups, species acute toxicity, and acute HC5s for 186 organic compounds (neutral and ionic). Toxicity predictions and acute HC5 estimates were validated against measured acute toxicity data compiled for HF substances. This case study supports the gTSM as an efficient, cost-effective computational tool for rapid aquatic hazard assessment of diverse organic chemicals. Environ Toxicol Chem 2024;43:1161-1172. © 2024 ExxonMobil Petroleum and Chemical BV. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Research Progress of Extracellular Vesicles-Loaded Microneedle Technology.

Microneedles (MNs), renowned for their painless and minimally invasive qualities, exhibit significant potential for facilitating effective drug delivery, vaccination, and targeted sample extraction. Extracellular vesicles (EVs), serving as cargo for MNs, are naturally occurring nanovesicles secreted by cells and characterized by novel biomarkers, low immunogenicity, and cell-source-specific traits. MNs prove instrumental in extracting EVs from the sample fluid, thereby facilitating a promising diagnostic and prognostic tool. To harness the therapeutic potential of EVs in tissue repair, MNs with sustained delivery of EVs leverage micron-sized channels to enhance targeted site concentration, demonstrating efficacy in treating various diseases, such as Achillea tendinopathy, hair loss, spinal cord injury, and diabetic ulcers. EV-loaded MNs emerge as a promising platform for repair applications of skin, cardiac, tendon, hair, and spinal cord tissues. This review commences with an overview of MNs, subsequently delving into the role of EVs as cargo for MNs. The paper then synthesizes the latest advancements in the use of EV-loaded MNs for tissue regenerative repair, extending to research progress in extracting EVs from MNs for disease diagnosis and prognostic evaluations. It aims to offer valuable insights and forecast future research trajectories with the hope of inspiring innovative ideas among researchers in this field.

Cu3P Nanoarrays Derived from 7,7,8,8-Tetracyanoquinodimethane for High-Rate Electrocatalytic Oxygen Reactions of Lithium-Oxygen Batteries

Efficient electrocatalysis at the cathode is crucial for addressing the challenges faced by lithium-oxygen batteries (LOBs), including limited stability and low-rate capability. To develop an efficient cathode for aprotic LOBs, self-supported copper phosphide nanoarrays on carbon cloth are prepared at different heating rates via a phosphidation process using CuTCNQ nanoarrays. Different ramping rates have effects on particle size and intrinsic interaction, which in turn affect their catalytic properties. When phosphidation is carried out at a slow rate, it results in the formation of smaller, evenly distributed Cu3P particles on the nanoarrays (SG-Cu3P NAs/CC) compared to fast rate phosphidation (FG-Cu3P NAs/CC). As a result, SG-Cu3P NAs/CC exhibits lower resistance and a higher concentration of active sites than FG-Cu3P NAs/CC. The SG-Cu3P NAs/CC demonstrates LOBs with a low overpotential of 1.51 V at a high current rate of 1 mA cm−2 and a long cycle life of 115 cycles at 0.1 mA cm-2. The in situ Raman spectroscopy supports that Li2O2 is uniformly formed and decomposed on the SG-Cu3P NAs/CC surface. This study provides a compelling approach for the precise fabrication and analysis of binder-free, self-supported copper phosphides as highly efficient and stable materials for bifunctional oxygen electrocatalysis.

Synthesizing a transesterification catalyst via a condensation reaction and assessment of the mechanism using density functional theory

AbstractBACKGROUNDA solid acid (SPEI–EN–OHCMs) having dendritic –NH2 groups was prepared via oxidation of hydrothermal carbon microspheres (OHCMs) followed by a condensation reaction with the –NH2 groups of polyethyleneimine and sulfonation. The mechanism by which –COOH groups on the surfaces of OHCMs reacted with these –NH2 groups was assessed using density functional theory (DFT).RESULTActivation using a combination of 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS) was found to promote the formation of amide bonds such that –NH2 groups were bonded to the microsphere surfaces. This effect provided more bonding sites for –SO3H groups. The DFT results indicated that the energy barrier on the potential energy surface in the presence of EDC and NHS was lowered by 18.1 kcal mol−1. X‐ray photoelectron spectroscopy analyses also confirmed the introduction of –NH2 groups followed by –SO3H groups onto the surfaces of the OHCMs. The concentration of surface acid sites on SPEI–EN–OHCMs was found to be as high as 11.8 mmol g−1. Thermogravimetric data and elemental analysis results showed that the –SO3H groups on the SPEI–EN–OHCM surfaces were thermally stable below 180 °C.CONCLUSIONThe SPEI–EN–OHCMs catalyst was used to promote the transesterification reaction of waste frying oil with methanol. A trial with a methanol‐to‐oil molar ratio of 10:1 at 110 °C for 4 h gave a fatty acid methyl ester (FAME) yield of 92.3%. After four reuses, an SPEI–EN–OHCMs specimen provided a FAME yield of 54.3%. © 2024 Society of Chemical Industry (SCI).

Nitrogen-doped carbonaceous electrode modified by biological metal-organic framework for vanadium redox flow batteries

The biological metal-organic framework (Bio-MOF) is utilized to modify the carbonaceous electrode for the vanadium redox flow batteries. The microwave solvothermal method prepared the cobalt-based Bio-MOF on a graphite felt (GF) surface. Then, the nitrogen-doping graphite and porous structure formation were completed simultaneously during the carbonization process. Finally, electrochemical activation was conducted to remove cobalt metal from the GF electrode and raise the concentration of oxygen-containing functional group active sites. By in-situ Raman spectroscopy, the increase of disordered graphitic lattices could be observed by raising the potential from 0.6 V to 1.6 V. The microwave solvothermal method and electrochemical activation can effectively shorten the treatment time compared with the traditional solvothermal method and acidic etching processes. Among the carbonization parameters for Bio-MOF-covered GFs, maintaining the temperature at 900 °C for 2 h under an argon atmosphere is the most suitable. The annealed sample after electrochemical activation (BMDGF-900EA) displays 73.7 % energy efficiency at 120 mA cm−2 and possesses a 90 % retention rate of efficiency after 250 cycles at 180 mA cm−2. The superior performance results from more catalytic active sites, hydrophilic surface features, and larger specific surface area prove that this modification method derived from Bio-MOF indeed provides a novel and potential way to improve the VRFB performance.

Lanthanum partial substitution by basic cations in LaNiO3/CeO2 precursors to raise DFM performance for integrated CO2 capture and methanation

The influence of the adsorbent nature on the CO2 capture and in situ methanation efficiency of novel Dual Function Materials (DFMs) is studied. Several 20% La0.7A0.3NiO3/CeO2–type precursors, with La3+ partially substituted by basic metal oxides (Na, K, Ca and Ba) are prepared. Samples are deeply characterized before and after catalytic tests by XRD, N2 adsorption-desorption, H2-TPR, H2-TPD, STEM-EDS, XPS, CO2-TPD and H2-TPSR. Characterization results show that Ca2+ and Ba2+ cations accommodate better inside the perovskite structure, due to their similarity in oxidation state and ionic radius to La3+. Corresponding DFMs result in enhanced textural properties, more homogenous phase distribution and promoted surface basic sites accessibility and concentration. Finally, the higher proximity and interactions between CO2 adsorption and active sites enhances CH4 formation in a wider temperature window. The order of reactivity has been observed in terms of CH4 production: Ca-doped ≥ Ba-doped > non-doped ≫ Na-doped > K-doped. The 20% La0.7Ca0.3NiO3/CeO2-derived DFM improves methane production of the conventional 15% Ni-15% CaO/Al2O3 DFM (128.0 vs. 118.0 μmol CH4 g−1 at 400 ºC) in the presence of CO2 during the adsorption period, whereas the incorporation of O2 and/or NOx during the adsorption period shows similar detrimental effect in both cases. However, the partial confinement of Ni nanoparticles (NPs) on Ni-La2O3, Ni-CaO or La-Ce-O interfaces prevents synthesized DFM from deactivation and promotes its regenerability related to the conventional formulation. Thus, Ca doping emerges as the more effective way of tailoring CO2 adsorption and in-situ hydrogenation to CH4 efficiency of 20% LaNiO3/CeO2-derived DFMs.

Influence of two asphaltenes on the formation and development of mesophase in fluid catalytic cracking (FCC) slurry oil

Asphaltene constitutes the heaviest component in fluid catalytic cracking (FCC) slurry oil. Mesophase pitch are prepared from FCC slurry oil by adding two asphaltenes (CL-As/JB-As) with distinct structure, and the influence of asphaltenes on the formation of mesophase is investigated. The findings suggest that an addition of CL-As within the range of 0–20 wt% is advantageous for the development and formation of mesophase. The addition of JB-As less than 1 wt% facilitates the formation and development of mesophase, while the opposite is observed with JB-As greater than 1 wt%. This is due to the light fraction of JB-As (JB-As-L), which is similar to CL-As and possesses appropriate concentrations of reactive sites that promote the formation of mesophase. However, the prevalence of alkane-branched chains is most densely concentrated in the heavy fraction of JB-As (JB-As-H), which leads to an excessive concentration of reactive sites. The predominance of JB-As-H causes an increase of the system's viscosity in the early stage so that the collision of polycyclic aromatic hydrocarbon macromolecules is reduced and the formation of the mesophase is postponed eventually. This provides a profound understanding of the preparation of high-quality mesophase pitch by regulating the properties of raw materials.

Labile dissolved organic matter (DOM) and nitrogen inputs modified greenhouse gas dynamics: A source-to-estuary study of the Yangtze River

Although rivers are increasingly recognized as essential sources of greenhouse gases (GHG) to the atmosphere, few systematic efforts have been made to reveal the drivers of spatiotemporal variations of dissolved GHG (dGHG) in large rivers under increasing anthropogenic stress and intensified hydrological cycling. Here, through a source-to-estuary survey of the Yangtze River in March (spring) and October (autumn) of 2018, we revealed that labile dissolved organic matter (DOM) and nitrogen inputs remarkably modified the spatiotemporal distribution of dGHG. The average partial pressure of CO2 (pCO2), CH4 and N2O concentrations of all sampling sites in the Yangtze River were 1015 ± 225 μatm, and 87.5± 36.5 nmol L−1, and 20.3 ± 6.6 nmol L−1, respectively, significantly lower than the global average. In terms of longitudinal and seasonal variations, higher GHG concentrations were observed in the middle-lower reach in spring. The dominant drivers of spatiotemporal variations in dGHG were labile, protein-like DOM components and nitrogen level. Compared with the historical data of dGHG from published literature, we found a significant increase in N2O concentrations in the Yangtze River during 2004–2018, and the increasing trend was consistent with the rising riverine nitrogen concentrations. Our study emphasized the critical roles of labile DOM and nitrogen inputs in driving the spatial hotspots, seasonal variations and annual trends of dGHG. These findings can contribute to constraining the global GHG budget estimations and controls of GHG emission in large rivers in response to global change.

Impact of Sr Addition on Zirconia-Alumina-Supported Ni Catalyst for COx-Free CH4 Production via CO2 Methanation.

Zirconia-alumina-supported Ni (5Ni/10ZrO2+Al2O3) and Sr-promoted 5Ni/10ZrO2+Al2O3 are prepared, tested for carbon dioxide (CO2) methanation at 400 °C, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, surface area and porosity, infrared spectroscopy, and temperature-programmed reduction/desorption techniques. The CO2 methanation is found to depend on the dispersion of Nickel (Ni) sites as well as the extent of stabilization of CO2-interacted species. The Ni active sites are mainly derived from the reduction of 'moderately interacted NiO species'. The dispersion of Ni over 1 wt % Sr-promoted 5Ni/10ZrO2+Al2O3 is 1.38 times that of the unpromoted catalyst, and it attains 72.5% CO2 conversion (against 65% over the unpromoted catalyst). However, increasing strontium (Sr) loading to 2 wt % does not affect the Ni dispersion much, but the concentration of strong basic sites is increased, which achieves 80.6% CO2 conversion. The 5Ni4Sr/10ZrO2+Al2O3 catalyst has the highest density of strong basic sites and the highest concentration of active sites with maximum Ni dispersion. This catalyst displays exceptional performance and achieves approximately 80% CO2 conversion and 70% methane (CH4) yield for up to 25 h on steam. The unique acidic-basic profiles composed of strong basic and moderate acid sites facilitate the sequential hydrogenation of formate species in the COx-free CH4 route.

General purpose propofol target-controlled infusion using the marsh model with adjusted weight input.

We report a simple method for adjusting the weight input of the Marsh target-controlled infusion (TCI) model such that the resulting infusion regime closely mimics the behaviour of the Eleveld model, thereby making the Marsh model more precise for patients at the extremes of age and body mass index. To assess the performance of our method, we simulated 2768 subjects with diverse combinations of age, weight, height and sex undergoing a hypothetical four-hour propofol TCI using both the Marsh model with our weight adjustment and the Eleveld model. The weight adjusted Marsh model produced infusion regimes and corresponding effect site concentrations closely mimicking that of the Eleveld model at all time points, with median and maximum absolute performance errors less than 8.1% and 20.3%, respectively, across the entire cohort. Our weight adjustment method is a simple and robust way of improving the precision of the Marsh model in patients at extremes of age and body mass index, until general purpose TCI models for propofol, such as the Eleveld model, become more widely available in commercial infusion pumps.

Hierarchical Deep Reinforcement Learning-Based Propofol Infusion Assistant Framework in Anesthesia.

This article aims to provide a hierarchical reinforcement learning (RL)-based solution to the automated drug infusion field. The learning policy is divided into the tasks of: 1) learning trajectory generative model and 2) planning policy model. The proposed deep infusion assistant policy gradient (DIAPG) model draws inspiration from adversarial autoencoders (AAEs) and learns latent representations of hypnotic depth trajectories. Given the trajectories drawn from the generative model, the planning policy infers a dose of propofol for stable sedation of a patient under total intravenous anesthesia (TIVA) using propofol and remifentanil. Through extensive evaluation, the DIAPG model can effectively stabilize bispectral index (BIS) and effect site concentration given a potentially time-varying target sequence. The proposed DIAPG shows an increased performance of 530% and 15% when a human expert and a standard reinforcement algorithm are used to infuse drugs, respectively.

5Ni/MgO and 5Ni/MgO + MOx (M = Zr, Ti, Al) Catalyst for Hydrogen Production via Dry Reforming of Methane: Promotor-Free, Cost-Effective, and Handy Catalyst System

Utilization of CO2 as a promising oxidant under dry reforming methane (DRM) can mitigate two greenhouse gases (CO2 and CH4) together, as well as DRM reaction may be a source of H2 energy in future. The cost-effective and handy catalyst preparation procedures like mixing, drying and calcining may turn this reaction from lab to industry. In this line, herein, 5Ni/MgO and 5Ni/MgO + MOx (M = Zr, Ti, Al) catalysts were prepared, investigated for DRM and characterized by X-ray diffraction, Raman, temperature programmed reduction/desorption, thermogravimetry and transmission electron microscope. Among the prepared catalysts, the 5Ni/MgO + TiO2 catalyst exhibits the highest concentration of active Ni sites enhanced reducibility under oxidizing and reducing environments, but catalytic excellency is hindered by severe graphitic-type coke deposition. On the other hand, the 5Ni/MgO + Al2O3 catalyst predominantly comprises metallic Ni resulting from the reduction of “strongly interacted NiO”, expanded surface area and the highest concentration of easily accessible active sites, contributing to its superior performance (H2 yield ~ 71% up to 430 min time on stream) under oxidizing and reducing conditions during DRM. The outstanding performance of the 5Ni/MgO + Al2O3 catalyst marks a significant stride towards the development of an industrially viable, cost-effective, and convenient catalyst system for DRM.Graphical

Basic Properties of ZnO, Ga2O3, and MgO—Quantitative IR Studies

In our previous study, we elaborated a method of determination of concentrations of the basic sites O2− and OH− in a quantitative IR study of CO2 adsorption. Previous adsorption studies or TPD experiments only provided the total basicity without distinguishing between O2− and OH−. In this study, we determined the concentration of O2− and OH− on ZnO, Ga2O3, and MgO surfaces. The basicity of ZnO and MgO was found to be significantly higher than that of Ga2O3. The surface of ZnO was rich in O2−, the contribution of OH− was very small, and the Ga2O3 surface contained mainly OH−. For MgO, the contribution of O2− and OH− was comparable. According to the IR results, only a small fraction of all surface hydroxyls were sufficiently basic to react with CO2. The partial dehydroxylation changed the proportion of the concentrations of O2− and OH− on the oxides. We also elaborated upon a new method to determine the total concentration of basic sites via CO2 desorption monitored using IR. For all the oxides, we studied the sum of the concentrations of O2− and OH−, as determined in our quantitative IR studies, to find whether they were comparable with the total basicity determined in the desorption experiments.

Annealing of hydrogen trap sites in displacement-damaged EUROFER

For future fusion power plants, the reduced activation ferritic/martensitic (RAFM) steel EUROFER is considered to be the primary choice as a structural material for plasma facing components (PFC) of the first wall, such as the blanket modules. Its exposure to high energy fusion neutrons will lead to creation of radiation-induced defects, which could act as trapping sites for hydrogen isotopes (HI) and consequently, strongly affect HI diffusion and retention. For predictive simulations of HI retention, the concentration of these trap sites needs to be known as a function of the temperature. In this work, EUROFER samples are irradiated by 20 MeV W-ions at 290 K to create displacement damage. Subsequently, they are exposed to deuterium (D) plasma at 370 K to decorate the created defects. Partial thermal desorption spectroscopy (TDS) is conducted in 50 K steps up to 620 K. D depth profiles are determined by nuclear reaction analysis (NRA) after each partial-TDS step. Following this analysis, the defects are again decorated with D and the D depth profiles are measured again by NRA to monitor the evolution of the concentration of trap sites. Most of the D is lost already at 470 K due to thermal de-trapping. Full recovery of the displacement damage is reached at 620 K.

Hydrodeoxygenation of mixtures of biomass-derived model compound oxygenates over Pt/HY catalysts

In this study, a systematic analysis of the effect of three biomass pyrolysis oxygenates, viz., acetic acid, cyclopentanone and furfural, on the hydrodeoxygenation (HDO) of guaiacol is performed. Bifunctional Pt/HY catalysts with different Si/Al ratios were screened for the HDO of guaiacol. Guaiacol conversion and the cyclohexane yield increased with the concentration of acid sites in the zeolites. The presence of acetic acid and cyclopentanone did not affect the guaiacol conversion and the product selectivity, while guaiacol conversion decreased significantly in the presence of furfural. The effects of temperature, reaction time, and the guaiacol-furfural molar ratio on the HDO of guaiacol were studied. The time evolution of products showed that the furan ring opening influences the conversion of guaiacol.Quantum chemicaldensity functional theorycalculations using individual and binary model compounds revealed the decrease in adsorption energy of guaiacol over Pt (111) in the presence of furfural.

Creating Remarkably Moisture‐ and Air‐Stable Macromolecular Lewis Acid by Integrating Borane within the Polymer Chain: A Highly Active Catalyst for Homo(co)polymerization of Epoxides

AbstractBorane‐based Lewis acids (LA) play an indispensable role in the Lewis pair (LP) mediated polymerization. However, most borane‐based LPs are moisture‐ and air‐sensitive. Therefore, development of moisture and air‐stable borane‐based LP is highly desirable. To achieve this goal, the concept of “aggregation induced enlargement effects” by chemically linking multiple borane within a nanoscopic confinement was conceived to create macromolecular LA. Accordingly, an extremely moisture and air stable macromolecular borane, namely, PVP‐1B featuring poly(4‐vinylphenol) backbone, was constructed. The concentration of borane active site is greatly higher than average concentration due to local confinement. Therefore, an enhanced activity was observed. Moreover, the local LA aggregation effects allow its tolerance to air and large amount of chain transfer agent. Consequently, PVP‐1B showed remarkable efficiency for propylene oxide (PO) polymerization at 25 °C (TOF=27900 h−1). Furthermore, it enables generation of well‐defined telechelic poly (CHO‐alt‐CO2) diol (0.6–15.3 kg/mol) with narrow Đs via copolymerizing cyclohexene oxide and CO2 at 80 °C. This work indicates unifying multiple borane within a polymer in a macromolecular level shows superior catalytic performance than constructing binary, bi(multi)functional systems in a molecular level. This paves a new way to make functional polyethers.

Creating Remarkably Moisture- and Air-Stable Macromolecular Lewis Acid by Integrating Borane within the Polymer Chain: A Highly Active Catalyst for Homo(co)polymerization of Epoxides.

Borane-based Lewis acids (LA) play an indispensable role in the Lewis pair (LP) mediated polymerization. However, most borane-based LPs are moisture- and air-sensitive. Therefore, development of moisture and air-stable borane-based LP is highly desirable. To achieve this goal, the concept of "aggregation induced enlargement effects" by chemically linking multiple borane within a nanoscopic confinement was conceived to create macromolecular LA. Accordingly, an extremely moisture and air stable macromolecular borane, namely, PVP-1B featuring poly(4-vinylphenol) backbone, was constructed. The concentration of borane active site is greatly higher than average concentration due to local confinement. Therefore, an enhanced activity was observed. Moreover, the local LA aggregation effects allow its tolerance to air and large amount of chain transfer agent. Consequently, PVP-1B showed remarkable efficiency for propylene oxide (PO) polymerization at 25 °C (TOF=27900 h-1 ). Furthermore, it enables generation of well-defined telechelic poly (CHO-alt-CO2 ) diol (0.6-15.3 kg/mol) with narrow Đs via copolymerizing cyclohexene oxide and CO2 at 80 °C. This work indicates unifying multiple borane within a polymer in a macromolecular level shows superior catalytic performance than constructing binary, bi(multi)functional systems in a molecular level. This paves a new way to make functional polyethers.

Amino-grafted basic mesoporous silicas: a type of highly performant catalysts for the green synthesis of 2-amino-4H-chromenes

Novel series of amino-grafted mesoporous silica materials applied to the green and efficient synthesis of 2-amino-4H-chromenes, from salicylaldehydes and ethyl cyanoacetate, under mild and free-solvent conditions, is herein reported for the first time. These catalysts are easily prepared by using the post-synthetic method, by functionalizing the SBA-15 silica with the corresponding amino silanes. The observed catalytic performance is mainly controlled by the type and concentration of basic sites. The methodology herein reported could be considered as an environmentally friendly alternative for the selective chromene synthesis, which allows to achieve high yields in short reaction times using notably small amounts of the catalysts. The experimental results are also supported with theoretical calculations, which suggest that the amine groups at the silica surface are behind the observed catalytic performance with the assistance of the silica matrix.

Modelling and optimization of Li+ extraction from brine with high Mg/Li ratio by electrochemically switched ion exchange considering thermodynamics and dynamics simultaneously

Electrochemically switched ion exchange (ESIX) technology has been proven to be an efficient and environmental-friendly method for extracting Li+ from brine lakes. To deeply understand and mathematically express the underlying physical process of Li+ extraction in ESIX, a model is developed to describe Li+ extraction from brine lakes with a high Mg/Li mass ratio (500:1) by ESIX with an electrode coated with λ-MnO2 film. The kinetics and thermodynamics of the Li+ extraction process is considered simultaneously by coupling the Frumkin-Bulter-Volmer theory modified by electroactive site concentration with a modified Gouy-Chapman-Stern model. The local sensitivity analysis indicates that the performance of ESIX in Li+ adsorption is greatly influenced by cell voltage, film mass, and Stern capacitance of carbon black film, whereas these parameters have little effect on Mg2+ adsorption. The individual parameter analysis elucidates that the mass and Stern capacitance of carbon black film can regulate the potential drop distributions in different regions of ESIX system, resulting in a maximum Li+ extraction efficiency of 90.22 % due to the increased driving force in the faradic reaction and reduced charge transfer resistance. The optimization of combined parameters indicates that the optimum operation can be achieved at the conditions with a cell voltage ranging between 1.0 and 1.2 V, a Stern layer capacitance with electric double layer volume for carbon black film of 5.4 × 107 F/L, and an initial Li+ content of the treatment solution: carbon black film: λ-MnO2 film mass ratio of 0.1 kg: 9 kg: 8 kg.