Low Molar Ratio Research Articles

Optimization of Hybrid Microwave Curing Approach Based On the Performance of Metakaolin-Based Geopolymer Mortars

Geopolymer binders have been highlighted due to their low carbon emission during production and processing. While metakaolin and F-type fly ash are commonly used as raw materials for aluminosilicate-based geopolymers, the long heat-curing requirements for hardening and strength development still pose challenges. This paper investigates the possible use of a hybrid microwave curing technique to design a set-on-demand approach to reduce the duration of heat curing in metakaolin-based geopolymer. The experimental design was established for samples with three different molar ratios (MR; 1.3,1.5, and 1.7) containing metakaolin, fly ash, and silica fume. Samples were subjected to 3 different curing regimes: oven curing, microwave (MW) curing, and hybrid curing (a combination of optimized microwave and oven curing). The performance evaluation was based on compressive strength, dimensional stability, and alkali leaching (efflorescence). Implementing only MW curing resulted in a significant decrease in compressive strength compared to their counterpart oven-cured samples. The reduction of compressive strength was more pronounced at lower molar ratios. The design of a hybrid curing approach where a portion of oven curing was replaced by MW resulted in a higher strength development than those only cured with MW. Similarly, the efficiency of hybrid curing was more pronounced in samples having MR of 1.5 and 1.7. Using MW curing in the geopolymer binders did not affect the alkali leaching; however, it increased the material’s drying shrinkage. Results showed that replacing a portion of oven curing with microwave curing in a hybrid approach can increase the operation speed and the hardening rate without significantly decreasing compressive strength.

Metal-Nitrate-Catalyzed Levulinic Acid Esterification with Alkyl Alcohols: A Simple Route to Produce Bioadditives

This work developed an efficient route to produce fuel bioadditive alkyl levulinates. Special attention was paid to butyl levulinate, which is a bioadditive with an adequate carbon chain size to be blended with liquid fuels such as diesel or gasoline. In this process, levulinic acid was esterified with butyl alcohol using cheap and commercially affordable metal nitrates as catalysts, producing bioadditives at more competitive costs. Iron (III) nitrate was the most active and selective catalyst toward butyl levulinate among the salts evaluated. In solvent-free conditions, with a low molar ratio and catalyst load (1:6 acid to alcohol, 3 mol% of Fe (NO3)3), conversion and selectivity greater than 90% after an 8 h reaction was achieved. A comparison of the iron (III) nitrate with other metal salts demonstrated that its superior performance can be assigned to the highest Lewis acidity of Fe3+ cations. Measurements of pH allow the conclusion that a cation with high Lewis acidity led to a greater H+ release, which results in a higher conversion. Butyl levulinate and pseudobuty levulinate were always the primary and secondary products, respectively. The consecutive character of reactions between butyl alcohol and levulinic acid (formation of the pseudobutyl levulinate and its conversion to butyl levulinate) was verified by assessing the reactions at different temperatures and conversion rates. A variation in Fe(NO3)3 catalyst load impacted the conversion much more than reaction selectivity. The same effect was verified when the reactions were carried out at different temperatures. The reactivity of alcohols with different structures depended more on steric hindrance on the hydroxyl group than the size of the carbon chain. A positive aspect of this work is the use of a commercial iron nitrate salt as the catalyst, which has advantages over traditional mineral acids such as sulfuric and hydrochloric acids. This solid catalyst is not corrosive and avoids neutralization steps after reactions, minimizing the generation of residues and effluents.

Size-controlled synthesis of cobalt phosphide (Co2P) nanoparticles and their application in non-enzymatic glucose sensors via a carbon fiber/Co2P composite

In this study, we synthesized Co2P nanoparticles using a solid-state phosphorization method and evaluated the electrocatalytic response to glucose oxidation reaction (GORs). The influence of synthesis conditions on the particle size, morphology of Co2P species and formation of byproducts is discussed. A lower molar ratio of the phosphorus precursor leads to a decrease in the generation of byproducts. In addition, the calcination temperature and time greatly influence the purity level of the Co2P species and its particle size. Thus, we obtained three pure Co2P nanoparticles with different sizes and morphologies. Significant differences in their electrocatalytic activity against the GOR are observed depending on the size of the particles, being the smaller ones the most efficient. Based on Tafel analysis, a higher catalytic activity was observed for the carbon fibre (CF)/Co2P composite compared to Co2P, which presented a greater onset potential and low response in current density. Tafel slopes close to 120 mV/dec were obtained for both materials, indicating that the mechanism is independent of the type of Co2P-based material used. Finally, the performance of the GCE/CF/Co2P sensor was demonstrated by amperometric measurements, with a sensitivity of 409 µAmM-1cm-2, a linear range between 39.4 µM and 150 µM, and a detection limit of 0.97 µM, analytical characteristics better than those obtained for other cobalt phosphide-based sensors reported in the literature. In addition, the GCE/CF/Co2P sensor shows excellent selectivity and demonstrated to be competitive compared to other Co-based non-enzymatic glucose sensors.

Reduction of organic matter containing benzimidazole and toxicity in real livestock wastewater through advanced oxidation processes

Livestock wastewater (LWW) has a complex characteristic of high organic matter content, metals, nutrients, and pharmaceutical compounds. Advanced oxidation processes (AOP) are a potential option for treating this wastewater. This study evaluated real LWW and the performance of UV/H2O2 and UV/peroxymonosulfate (UV/PMS) for its treatment. The experiments were conducted in a UV photoreactor (16 mW/m2, λ = 254 nm). The oxidant agents (Ox) tested were H2O2 and PMS, each at low, medium, and high TOC/Ox molar ratios. A pretreatment based on chemical precipitation was implemented. Annually, the LWW showed total organic carbon (TOC) values of 859 ± 13.37 mg/L, 168.85 ± 1.62 mg/L of total Kjeldahl nitrogen (TKN), and toxicity of 96% v/v. In the dry season, albendazole (ABZ) (95.3 ± 35.16 mg/L), Cu (4.3 ± 0.23 mg/L), Fe (3.8 ± 0.38 mg/L), and suspended solids (SS) (1015 ± 586.9 mg/L) were identified, so pretreatment was implemented. The UV/PMS process with the lowest molar ratio [TOC/Ox 1:0.75] removed significantly lower TOC concentrations (p < 0.05), but toxicity decreased entirely. The study of mineralization and toxicity provided insight into the changes in LWW during treatment with AOP. Furthermore, it contributed to establishing the technical basis for implementing efficient treatment processes.

Topochemical Modulations from 1D Iron Fluoride Precursor to 3D Frameworks.

Topochemical reactions are powerful pathways to modify inorganic extended structures, but the present approaches are limited by the degrees of freedom to tune the structural connectivity and dimensionality. In this work, we unveil a new topochemical bottom-up approach to tailor three-dimensional (3D) iron fluoride frameworks from the same one-dimensional (1D) FeF3.3H2O (IF) precursor upon reacting with iodide-based reagents (AI; A+ = Na+, K+, and NH4+). To elucidate their formation mechanism, a series of topochemical reactions are performed by varying the concentration of precursors, reaction temperatures, and durations, and their corresponding products are analyzed through X-ray diffraction, nuclear magnetic resonance, and Mössbauer spectroscopy techniques. Although the lower molar ratio of AI:IF (≈0.25:1.0) produces the same hexagonal tungsten bronze (HTB)-type AxFeF3, the topochemical reactions with higher AI:IF ratios yield weberite-Na1.95Fe2F7, tetragonal tungsten bronze (TTB)-K0.58FeF3, and pyrochlore-NH4Fe2F6 phases. Our density functional theory calculations attribute the formation of iron fluoride phases to their thermodynamic stability. Moreover, kinetics also play an important role in enabling weberite and HTB fluorides with high purity, while the pyrochlore-NH4Fe2F6 retains a minor HTB-(NH4)xFeF3 impurity. Overall, this work shows a new possibility of modulating the low-dimensional precursor to attain 3D frameworks with different structural arrangements via topochemical approaches.

Catalytic Dechlorination of Three Organochlorides by Recyclable Nano-Palladium-Engineered Natural Sponge with Formic Acid

Catalytic dechlorination of organic chlorides by palladium (Pd) with HCOOH represents one of the most effective and promising techniques for environmental remediation. In this study, we adopted alkaline-modified porous natural sponge as support of a Pd nanocatalyst (Pd@M-Sponge) and HCOOH as a hydrogen source for the hydrodechlorination of florfenicol (FF), o-chlorophenol (o-CP), and p-chlorophenol (p-CP). Favorable conversion efficiency of FF, o-CP, and p-CP was achieved at 25 °C and atmospheric pressure attributed to the small diameter and high catalytic reactivity of the prepared Pd NPs, in addition to the slight internal mass transfer limitation of the prepared Pd@M-Sponge. High reaction rate constants were obtained even in the conditions of a low molar ratio of HCOOH to p-CP (10:1) and a high concentration of p-CP (500 mg/L). The prepared catalyst also demonstrated superior recyclability without any obvious decrease in catalytic reactivity in 20 successive p-CP dechlorination cycles. This work provides an ideal recyclable and cost-effective catalyst based on renewable and biocompatible natural material for the catalytic hydrodechlorination of chlorinated organic pollutants with formic acid and a new view for the exploration and designing of highly reactive and stable catalysts for hydrodechlorination.

Tuning CuMgAl-Layered Double Hydroxide Nanostructures to Achieve CH4 and C2+ Product Selectivity in CO2 Electroreduction.

Electrochemical CO2 reduction reaction (eCO2RR) over Cu-based catalysts is a promising approach for efficiently converting CO2 into value-added chemicals and alternative fuels. However, achieving controllable product selectivity from eCO2RR remains challenging because of the difficulty in controlling the oxidation states of Cu against robust structural reconstructions during the eCO2RR. Herein, we report a novel strategy for tuning the oxidation states of Cu species and achieving eCO2RR product selectivity by adjusting the Cu content in CuMgAl-layered double hydroxide (LDH)-based catalysts. In this strategy, the highly stable Cu2+ species in low-Cu-containing LDHs facilitated the strong adsorption of *CO intermediates and further hydrogenation into CH4. Conversely, the mixed Cu0/Cu+ species in high-Cu-containing LDHs derived from the electroreduction during the eCO2RR accelerated C-C coupling reactions. This strategy to regulate Cu oxidation states using LDH nanostructures with low and high Cu molar ratios produced an excellent eCO2RR performance for CH4 and C2+ products, respectively.

High H-abstraction efficiency of Ni(II)-Ni(III)-Ni(II) cycle mediated oxidation of aromatic contaminants by peroxydisulfate

Peroxydisulfate (PDS) activation has attracted great attention for the treatment of aromatic contaminants in wastewater. In this study, the synthesized β-Ni(OH)2 exhibits remarkable reactivity in the catalytic oxidation of aromatic contaminants of phenol and aniline under alkaline conditions at a low molar ratio of 2:1 between the initial PDS and aromatic contaminants, indicating that the aromatic contaminants have not been completely mineralized into CO2 and H2O. By means of quenching experiments, LSV analysis and various characterizations, we rule out the primary contributions of •OH, SO4•−, O2•−, 1O2 or the non-radically activated PDS complexes to the oxidation processes. Instead, the oxidation cycle of Ni(II)-Ni(III)-Ni(II) plays the predominant role. DFT calculations further reveal the strong adsorption of phenol (-1.217 eV) and aniline (-1.166 eV) on β-NiOOH surface, which subsequently initiates H-abstraction from phenol and aniline by β-NiOOH with low interaction barriers of 0.119 eV and 0.467 eV, respectively. The produced aromatic radicals then undergo polymerization to produce phenol and aniline polymers. This work provides new insight on PDS activation and offers an effective and cost-saving approach for the removal, recycling, and synthesis of aromatic polymers.

Formation of casein micelles from bovine caseins simulating human casein phosphorylation patterns: Micellar structure and in vitro infant gastrointestinal digestion

This study investigated the micellar structure and in vitro infant gastrointestinal digestion of formed casein micelles simulating human casein composition and phosphorylation patterns. Caseins were fractionated from bovine caseins and formulated according to human casein composition, i.e., β-, κ- and αs1-caseins with a ratio of 68:20:12. The formulated caseins were dephosphorylated for different times and were mixed to obtain mixed phosphorylation patterns (FC-MP) for β-casein, showing 0–5 phosphate groups comparable to human β-casein. The formulated caseins without dephosphorylation and with high dephosphorylation, showing 5 phosphate groups and 0–2 phosphate groups for β-casein, respectively, were categorized as high (FC-HP) and low phosphorylated (FC-LP). With the average mineral concentrations found in human milk, CaCl2, MgCl2, citrate and inorganic phosphate were added into the different formulated casein dispersions to obtain casein micelles (FM-HP, FM-MP and FM-LP). Compared to FM-HP, FM-MP was closer to human micelles in relation to particle size, micellar hydration, molar ratio of Ca:casein, morphology and internal structure, whereas FM-LP showed did not show a characteristic micellar structure and had a larger size and lower molar ratio of Ca:casein. For gastrointestinal digestion, FM-MP was closer to human micelles in terms of the gastric flocs, casein degradation rate, free amino groups, and molecular weight distribution of peptides compared to FM-HP, whereas FM-LP showed larger flocs and lower casein degradation rate. These results show the significance of post-translational phosphorylation in facilitating the assembly of caseins into micellar structures, indicating the potential to form human-like micelles for application in infant formulae.

Multifunctional asymmetric bi-ligand iron chelating agents towards low-cost, high performance, and stable zinc-iron redox flow battery

Zinc‑iron flow batteries hold great potential as stationary storage due to their attractive cost and abundance of materials; however, they still suffer from precipitation problems. This work demonstrates a novel asymmetric iron complex with bi-ligand from pyridine and disodium 4,5-dihydroxy-1,3-benzenedisulfonate (TIRON) to synergically reduces precipitation, improves the mass transport of the redox-active species, and lowers the electron transfer resistance. The low activation barrier of mixed complexes calculated via the Density Functional Theory (DFT) explains the ease of redox reaction, which is reflected in the low overpotential voltage in the Fe//Fe symmetrical cell. Moreover, no change in Raman and Fourier-transform infrared spectroscopy peaks after symmetrical cell cycling confirms the stability of the mixed complexes catholyte. Contrary to other works, our strategy requires a lower molar ratio of complexes per iron, while still yields a superior capacity of 6.81 Ah/L. From its outstanding capacity utilization, the overall cost of the electrolytes for the mixed complexes system is only $26.3/kWh, which is lower than the non-complex iron system at $42.9/kWh. Additionally, the mixed complexes battery can be operated stably for >200 cycles. Our perspective on eco-friendly and low-cost catholyte design accelerates development towards reliable stationary storage with high performance and stability.

Thermal Properties and Drying Shrinkage Performance of Palm Kernel Shell Ash and Rice Husk Ash-Based Geopolymer Concrete.

This study aims to develop suitable formulations of geopolymer concrete (GPC) by varying the percentages of the geopolymer with aggregates and evaluating the performances in thermal and mechanical properties of palm kernel shell ash (PKSA)-GPC compared to rice husk ash (RHA)-GPC and ordinary Portland cement concrete (OPCC). Preliminary tests were conducted to select the best mix design ratios before casting the specimens. Then, the performance of the PKSA-GPC, RHA-GPC and OPCC specimens was evaluated based on their thermal performance and drying shrinkage. The mix designs of PKSA-GPC 70:30, PKSA-GPC 60:40, PKSA-GPC 50:50 and PKSA-GPC 66.6:33.3 were found to produce an acceptable consistency, rheological and thixotropic behaviour for the development of the GPC. PKSA-GPC showed a better thermal performance than the RHA-GPC and OPCC due to their strong and dense intumescent layers and slow temperature increment upon exposure to a high flame temperature from ambient temperature to 169 °C. The low molar ratio of the Si/Al present in the PKSA-GPC created a thermally stable intumescent layer. In the drying shrinkage test, PKSA-GPC 60:40 and RHA-GPC 60:40 shared an equal drying shrinkage performance (5.040%) compared to the OPCC (8.996%). It was observed that microcrack formation could significantly contribute to the high shrinkage in the PKSA-GPC 50:50 and RHA-GPC 70:30 specimens. The findings of this study show that PKSA could be incorporated into GPC as a fire-retardant material due to its capability of prolonging the spread of fire upon ignition and acting as an alternative to the conventional OPCC.

Introduced gas regulating fast and highly exothermic reactions with in situ gas generation in microreactors

AbstractThe oxidation of cyclohexanol/cyclohexanone with nitric acid as a fast and highly exothermic process was hard to control at low molar ratios of oxidant to organic substrate even in microreactors. Process of runaway gas generation was observed due to the local hot spots, which decreased the selectivity of adipic acid. Additional gas was introduced into microreactors before the reaction, changing the previous wave annular flow to the uniform slug flow. Through the microscopic high‐speed photography and CFD simulation, it was found that the internal convection made the reactant molecules in the aqueous slug distribute evenly instead of gathering near the interface before, thus eliminating the local hot spots and stabilizing the hydrodynamic characteristics. The reaction performance was evaluated under different conditions, and a higher adipic acid selectivity of 93.6% was achieved at a molar ratio of 6.7 with the combination of microreactors and conventional reactors.

Exploring Whole Cells of Rhizopus oryzae for Efficient Synthesis of Emollient Esters: Bioesters for Cosmetics

Production of esters, organic compounds with emollient, emulsifying, and aromatic properties is growing due to high demand and their applications in the cosmetics industry. The synthesis of these compounds involves the reaction between a carboxylic acid and an alcohol, which can be catalyzed by lipases. In this context, the objective of this study was to produce mycelium-bound lipases of the fungus Rhizopus oryzae through submerged cultivation, with the aim of applying them in the synthesis of ethylene glycol oleate, ethylene glycol stearate, and isoamyl palmitate esters, which are relevant to the cosmetic industry. The influence of solvent usage (heptane), biocatalyst mass, and acid/alcohol molar ratio was evaluated in the esterification reactions. In the synthesis of the three tested esters, and in the presence of heptane solvent, an equimolar ratio (1:1) of each acid and alcohol with a concentration of 0.01 mol L-1 was utilized. The reactions were performed in agitated Erlenmeyer flasks at 40 °C with an agitation speed of 200 rpm. The lipolytic biomass of Rhizopus oryzae showed better performance in the synthesis of isoamyl palmitate, achieving a maximum conversion of 83% in 24 h of reaction using 0.30 g of lipolytic biomass and the solvent heptane. In addition, it was observed that higher concentrations of catalyst biomass (0.45 g) and lower molar ratios (1:1.5) of acid to alcohol resulted in a higher conversion of isoamyl palmitate ester, reaching conversions of 48.59 and 83.11%, respectively.

Single protein encapsulated SN38 for tumor-targeting treatment

BackgroundThe alkaloid camptothecin analog SN38 is a potent antineoplastic agent, but cannot be used directly for clinical application due to its poor water solubility. Currently, the prodrug approach on SN38 has resulted in 3 FDA-approved cancer therapeutics, irinotecan, ONIVYDE, and Trodelvy. However, only 2–8% of irinotecan can be transformed enzymatically in vivo into the active metabolite SN38, which severely limits the drug’s efficacy. While numerous drug delivery systems have been attempted to achieve effective SN38 delivery, none have produced drug products with antitumor efficacy better than irinotecan in clinical trials. Therefore, novel approaches are urgently needed for effectively delivering SN38 to cancer cells with better efficacy and lower toxicity.MethodsBased on the unique properties of human serum albumin (HSA), we have developed a novel single protein encapsulation (SPE) technology to formulate cancer therapeutics for improving their pharmacokinetics (PK) and antitumor efficacy and reducing their side effects. Previous application of SPE technology to doxorubicin (DOX) formulation has led to a promising drug candidate SPEDOX-6 (FDA IND #, 152154), which will undergo a human phase I clinical trial. Using the same SPE platform on SN38, we have now produced two SPESN38 complexes, SPESN38-5 and SPESN38-8. We conducted their pharmacological evaluations with respect to maximum tolerated dose, PK, and in vivo efficacy against colorectal cancer (CRC) and soft tissue sarcoma (STS) in mouse models.ResultsThe lyophilized SPESN38 complexes can dissolve in aqueous media to form clear and stable solutions. Maximum tolerated dose (MTD) of SPESN38-5 is 250 mg/kg by oral route (PO) and 55 mg/kg by intravenous route (IV) in CD-1 mice. SPESN38-8 has the MTD of 45 mg/kg by IV in the same mouse model. PK of SPESN38-5 by PO at 250 mg/kg gave mouse plasma AUC0-∞ of 0.05 and 4.5 nmol × h/mL for SN38 and SN38 glucuronidate (SN38G), respectively, with a surprisingly high molar ratio of SN38G:SN38 = 90:1. However, PK of SPESN38-5 by IV at 55 mg/kg yielded much higher mouse plasma AUC0-∞ of 19 and 28 nmol × h/mL for SN38 and SN38G, producing a much lower molar ratio of SN38G:SN38 = 1.5:1. Antitumor efficacy of SPESN38-5 and irinotecan (control) was evaluated against HCT-116 CRC xenograft tumors. The data indicates that SPESN38-5 by IV at 55 mg/kg is more effective in suppressing HCT-116 tumor growth with lower systemic toxicity compared to irinotecan at 50 mg/kg. Additionally, SPESN38-8 and DOX (control) by IV were evaluated in the SK-LMS-1 STS mouse model. The results show that SPESN38-8 at 33 mg/kg is highly effective for inhibiting SK-LMS-1 tumor growth with low toxicity, in contrast to DOX’s insensitivity to SK-LMS-1 with high toxicity.ConclusionSPESN38 complexes provide a water soluble SN38 formulation. SPESN38-5 and SPESN38-8 demonstrate better PK values, lower toxicity, and superior antitumor efficacy in mouse models, compared with irinotecan and DOX.

Ultrasonic-assisted synthesis of mono- and diacylglycerols and purification of crude glycerol derived from biodiesel production

Production of monoacylglycerols (MAGs) and diacylglycerols (DAGs) via glycerolysis of fatty acid methyl esters (FAME) with glycerol (G) using an ultrasonic bath and probe was investigated. The glycerolysis using an ultrasonic bath at the optimum condition: KOH 3 wt% of glycerol, ethanol 5.5% v/v solution, and ultrasonic frequency 35 kHz yielded only 3.30% MAGs and 11.47% DAGs because the temperature was limited at 80 °C. The effect of four variables including the molar ratio of G:FAME (2.5:1–3.5:1), KOH (2.5–3.5 wt% of G), time (45–75 min), and temperature (140–160 °C) for glycerolysis utilizing an ultrasonic probe was studied and optimized by response surface methodology (RSM) and box-Behnken design (BBD). The condition: 2.82:1 G:FAME mol:mol, KOH 3.18 wt% of glycerol, 46.33 min, and 155.66 °C was recommended to achieve the highest MAGs (53.32%). To produce the most DAGs, a lower molar ratio, higher temperature, and longer time were suggested. Purification of crude glycerol by a simple multi-step process was proposed and a yield of 45 ± 0.34% was obtained with glycerol purity up to 95%. Glycerolysis of the purified and pure glycerol gave identical contents of MAGs and DAGs. Crystallization was operated to purify MAGs by investigating crystallization temperatures and solvents. Two-step crystallization obtained up to 96% MAG content and the major product was mono-palmitin. The synthesis of MAGs and DAGs was successful through the utilization of an ultrasonic probe, and crystallization was an effective method for MAG purification.

The Potential of Dendrimers as Alzheimer’s Disease Nanotherapeutics – Evidence of Antiamyloidogenic Properties Against Aβ42

AbstractBackgroundToday, available therapies for Alzheimer’s disease (AD) fail to modify the disease progression for the major AD clinical stages [1]. Therefore, new therapeutic approaches are an urgent need. Within nanomedicine, the use of nanomaterials, and dendrimers in particular, pose as promising AD therapies [2]. Dendrimers are globular macromolecules, with a well‐defined and hyperbranched structure, controllable nanosize (&lt;15 nm) and multivalent surface. Due to their intrinsic characteristics, they are first‐in‐class for drug delivery as they can act as efficient and multivalent carriers of different therapeutic molecules. In addition, dendrimers can be used as a drug per se. Different types of dendrimers display antioxidant, anti‐inflammatory, anti‐prion and anti‐amyloidogenic properties [2]. With that in mind, a proprietary family of dendrimers was explored to hamper Aβ (1‐42) peptide aggregation.MethodThe dendrimer was synthesized following a divergent strategy up to generation 3 and characterized by nuclear magnetic resonance and Fourier‐transform infrared spectroscopy. To analyse the dendrimer’s effect on fibrillation, the aggregation kinetics of the Aβ (1‐42) peptide was studied by thioflavin T (ThT) in the presence of different dendrimer concentrations. The aggregates’ morphology was assessed by transmission electron microscopy. The cytotoxicity of dendrimers was evaluated in SH‐SY5Y cells by metabolic assays (resazurin).ResultThe dendrimers showed to interfere with Aβ fibrillation in a concentration‐dependent manner. Their behaviour was similar to fibrillation inhibitors that can break fibrils as well [3]. When at a lower molar ratio than Aβ, dendrimers hampered fibrillation and small/nonfibrillar aggregates were present. For a higher molar ratio (dendrimer/peptide ratio &gt;1), they promoted Aβ fibrillation as more fibrils were present. More importantly, they were shown non‐toxic for neuroblastoma cells.ConclusionIn conclusion, these results show that these dendrimers can interfere with Aβ fibrillation. Future studies will be performed to understand the mechanism of action of this new family of dendrimers.

Efficient Formation of N-(1-Deoxy-d-ribulos-1-yl)-Glutathione via Limited Oxidation and Degradation of Glutathione during the Atmospheric-Vacuum Thermal Reaction.

The efficient preparation of the ribose-glutathione (Rib-GSH) Amadori rearrangement product (RG-ARP) as a potent precursor of meaty flavor was studied through the atmospheric-vacuum thermal reaction. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that the oxidation and degradation of GSH occurred during the preparation of RG-ARP via the atmospheric thermal reaction, especially at a low molar ratio of Rib to GSH and high reaction temperature. The RG-ARP and the ARPs derived from the products of GSH oxidation and degradation with the participation of Rib were identified by MS/MS as N-(1-deoxy-d-ribulos-1-yl)-glutathione, N-(1-deoxy-d-ribulos-1-yl)-cysteinylglycine, and N-(1-deoxy-d-ribulos-1-yl)-glutathione disulfide. The selective formation of RG-ARP was disrupted due to the multiple consumption pathways of GSH and Rib. The removal of water and the reduction of oxygen content during vacuum dehydration exhibited an obvious inhibitory effect on the oxidation of cysteinyl and the cleavage of glutamyl, limiting the oxidation and degradation of GSH. Meanwhile, the rapid evaporation of water promoted the molecular collision between the reactants, which allowed the glycation reaction of GSH to be advanced and fragmentation of RG-ARP to be inhibited at a mild dehydration temperature. Accordingly, the atmospheric-vacuum thermal reaction was proposed to limit the generation of secondary byproducts and enhance the yield of RG-ARP, enabling the RG-ARP yield to reach 49.23% at 80 °C and a molar ratio of 2:1 (Rib/GSH) for 20 min.

Integrated understanding of acidic deep eutectic solvent choline chloride: Oxalic acid pretreatment to enhance the enzymatic hydrolysis of rape straw

Using choline chloride (ChCl) as hydrogen-bonded-acceptor (HBA) and oxalic acid (OA) as hydrogen-bonded-donor (HBD), deep eutectic solvents (DESs) with different HBD-to-HBA molar ratios were synthesized to pretreat rape straw (RS). The influence of DES treatment on the RS chemical composition, structure change, and enzymatic saccharification were explored. DESs with low molar ratio of HBD-to-HBA exhibited low viscosity, which enhanced the pretreatment efficiency. When HBA-to-HBD molar ratio was 1:3, the delignification and enzymatic digestion efficiency were only 60.6% and 41.8%. As the molar ratio of OA decreased, delignification and enzymatic digestion efficiency increased to 83.6% and 96% (ChCl:OA = 3:1, mol/mol). After pretreatment (severity factor LogR0 =2.66), the cellulose accessibility and crystallinity increased from 353.0 to 691.1 mg/g and 35.4–64.2%, respectively. The lignin surface area decreased from 596.3 to 201.9 m2/g. The significant increase in cellulose accessibility and the decrease in lignin surface area explained the efficient enzymatic hydrolysis efficiency.

Autothermal Reforming of Methane: A Thermodynamic Study on the Use of Air and Pure Oxygen as Oxidizing Agents in Isothermal and Adiabatic Systems

In this paper, we analyze the autothermal reforming (ATR) of methane through Gibbs energy minimization and entropy maximization methods to analyze isothermic and adiabatic systems, respectively. The software GAMS® 23.9 and the CONOPT3 solver were used to conduct the simulations and thermodynamic analyses in order to determine the equilibrium compositions and equilibrium temperatures of this system. Simulations were performed covering different pressures in the range of 1 to 10 atm, temperatures between 873 and 1073 K, steam/methane ratio was varied in the range of 1.0/1.0 and 2.0/1.0 and oxygen/methane ratios in the feed stream, in the range of 0.5/1.0 to 2.0/1.0. The effect of using pure oxygen or air as oxidizer agent to perform the reaction was also studied. The simulations were carried out in order to maintain the same molar proportions of oxygen as in the simulated cases considering pure oxygen in the reactor feed. The results showed that the formation of hydrogen and synthesis gas increased with temperature, average composition of 71.9% and 56.0% using air and O2, respectively. These results are observed at low molar oxygen ratios (O2/CH4 = 0.5) in the feed. Higher pressures reduced the production of hydrogen and synthesis gas produced during ATR of methane. In general, reductions on the order of 19.7% using O2 and 14.0% using air were observed. It was also verified that the process has autothermicity in all conditions tested and the use of air in relation to pure oxygen favored the compounds of interest, mainly in conditions of higher pressure (10 atm). The mean reductions with increasing temperature in the percentage increase of H2 and syngas using air under 1.5 and 10 atm, at the different O2/CH4 ratios, were 5.3%, 13.8% and 16.5%, respectively. In the same order, these values with the increase of oxygen were 3.6%, 6.4% and 9.1%. The better conditions for the reaction include high temperatures, low pressures and low O2/CH4 ratios, a region in which there is no swelling in terms of the oxygen source used. In addition, with the introduction of air, the final temperature of the system was reduced by 5%, which can help to reduce the negative impacts of high temperatures in reactors during ATR reactions.

Fine-tuning polyamide nanofiltration membrane for ultrahigh separation selectivity of Mg2+ and Li+

The extraction of lithium resources from salt-lake brine has garnered increasing attention, and a critical challenge is to achieve an effective separation of Mg2+ and Li+. This study focuses on addressing this challenge using isophthaloyl chloride (IPC) in combination with trimesoyl chloride for completing interfacial polymerization (IP) with polyallylamine. The product is an unexpectedly highly permeable and permselective polyamide nanofiltration (NF) membrane that is effective for Mg2+/Li+ separation. Adjusting the acyl chloride density with IPC influenced the IP reaction progress, thereby yielding a polyamide layer with fine-tuned properties. Various characterization results demonstrated a significant difference in the positive chargeability between the NF membranes doped with IPC and the blank NF membrane without IPC, whereas other properties remained comparable. The optimal NF membrane prepared with a low IPC molar ratio of 33% exhibited highly positively charged and high permeability characteristics. Considering the remarkable advancements in separation performance and simplified fabrication process, a fine-tuned strategy for designing highly positively charged NF membranes holds great practical potential for the industrial development of lithium extraction from salt-lake brines.