Reaction Solution Research Articles

Experimental detection of the diamino-pentazolium cation and theoretical exploration of derived high energy materials

In this work, we realized the detection of diamino-pentazolium cation (DAPZ+) in the reaction solution experimentally and proved it to be meta-diamino-pentazole based on the transition state theory. Quantum chemical methods were used to predict its spectral properties, charge distribution, stability and aromaticity. Considering that DAPZ+ has excellent detonation properties, it was further explored by assembling it with N5−, N3− and C(NO2)3− anions, respectively. The results show a strong interaction between DAPZ+ and the three anions, which will have a positive effect on its stability. Thanks to the high enthalpy of formation and density, the calculated detonation properties of the three systems are exciting, especially [DAPZ+][N5−] (D: 10,016 m·s−1; P: 37.94 GPa), whose actual detonation velocity may very likely exceed CL-20 (D: 9773 m·s−1). There is no doubt that this work will become the precursor for the theoretical exploration of new polynitrogen ionic compounds.

Introduction and Quantification of Sulfide Ion Defects in Highly Crystalline CdS for Photocatalysis Applications

To evaluate and diversify, control methods for surface defects in photocatalysts have surged because of their significant effect on carrier dynamics and reactivity. Sulfide photocatalysts, wherein anion defects act as electron traps, are not as extensively researched as oxide photocatalysts, and therefore, the knowledge of defects remains incomplete. Herein, simple treatments such as grinding, alkali immersion, and annealing are used to introduce surface defects into CdS, which is a representative sulfide photocatalyst. Moreover, Pt‐loaded CdS is prepared by reducing Pt ions using electrons trapped in the defects. The amount of defects on the CdS surface is successfully estimated by quantifying the amount of unreacted Pt ions through the absorbance of the reaction solution. The results indicate that the defect density can be increased using any of these employed methods. The surface state varies with the introduction method, leading to significant changes in photocatalytic activity. Grinding induces particle refinement and amorphization, alkali immersion induces oxidation and hydroxylation, and annealing enables the formation of a sulfurized surface. These surface conditions degrade the photocatalytic activity, and therefore, introduction of defects under relatively mild conditions is preferred. Herein, the sample calcined at 473 K shows the highest photocatalytic activity.

Effects of Antifoaming Agents on Manufacturing Silver Dendrites Through Fluoride-Assisted Galvanic Replacement Reaction

Abstract In fluoride-assisted galvanic replacement reaction (FAGRR), metallic dendrites are formed simultaneously with hydrogen gas. However, the presence of hydrogen bubbles impedes the reduction of metallic ions to form metallic dendrites. This study investigates the FAGRR approach to manufacturing Ag dendrites where ethanol is incorporated into an AgNO3 reaction solution. The findings of this study demonstrate the efficacy of ethanol as an antifoaming agent in enhancing the deposition of the Ag dendrites during the FAGRR process. The antifoaming effect of ethanol becomes more intense at higher concentrations of AgNO3. The introduction of ethanol into FAGRR can significantly improve processing efficiency and yield in the limited time for manufacturing science and engineering.

Ornated hydrangea-like M-MO/graphitic porous carbon derived via direct carbonization of MOFs for electrooxidation of methanol in alkaline DMFC

Due to their low operating temperature, ease of storage, transportation, and low greenhouse gas emissions, direct methanol fuel cells (DMFC) are considered the best choice of fuel cells for energy conversion. Although its theoretical thermodynamic energy conversion efficiency is ~97 %, its achievable energy conversion efficiency is still in the range of 30–40 %. To improve the reaction kinetics, it is important to look for an electrocatalyst with low cost and high efficiency. In the present study, direct carbonization of [Ni, Cu, and (Ni/Cu)] metal-organic framework (MOF) was carried out under a nitrogen gas flow at 800 °C for 2.5 h, where the MOF precursor was completely converted into graphitic porous carbon well ornamented with Metal/Metal oxides (M/MO). The as-prepared nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), Fourier transform infrared (FTIR), and the Brunauer–Emmett–Teller technique (BET). The prepared materials were used as electrocatalysts in a methanol oxidation reaction solution in an alkaline solution. The cyclic voltammetry (CV) measurements for Ni-MOF, Cu-MOF, (Ni/Cu) MOF, Ni-MOF800, Cu-MOF800, and (Ni/Cu)MOF800 showed excellent current densities of 17, 1.05, 44.25, 30, 11.56, and 53 mA∙cm−2, respectively at 0.6 V with a scan rate of 50 mV∙s−1. Whereas, the retention percent value is (96.2 %) for Ni-MOF, (93.1 %) for (Ni/Cu) MOF800, (96.7 %) for (Ni/Cu) MOF, (87.5 %) for Ni-MOF800, (97 %) for Cu-MOF, and (50.2 %) for Cu-MOF800 after an hour. Since M/MO/C800 demonstrated remarkable catalytic activity in relation to methanol oxidation and an abundance of cheap value, it is regarded as a promising candidate for future electrooxidation catalysis of MeOH in direct methanol fuel cells (DMFCs).

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

A lateral flow assay for miRNA-21 based on CRISPR/Cas13a and MnO2 nanosheets-mediated recognition and signal amplification.

The point-of-care testing (POCT) of miRNA has significant application in medical diagnosis, yet presents challenges due to their characteristics of high homology, low abundance, and short length, which hinders the achievement of quick detection with high specificity and sensitivity. In this study, a lateral flow assay based on the CRISPR/Cas13a system and MnO2 nanozyme was developed for highlysensitive detection of microRNA-21 (miR-21). The CRISPR/Cas13a cleavage system exhibits the ability to recognize the specific oligonucleotide sequence, where two-base mismatches significantly impact the cleavage activity of the Cas13a. Upon binding of the target to crRNA, the cleavage activity of Cas13a is activated, resulting in the unlocking of the sequence and initiating strand displacement, thereby enabling signal amplification to produce a new sequence P1. When applying the reaction solution to the lateral flow test strip, P1 mediates the capture of MnO2 nanosheets (MnO2 NSs) on the T zone, which catalyzes the oxidation of the pre-immobilized colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) on the T zone and generates the blue-green product (ox-TMB). The change in gray value is directly proportional to the concentration of miR-21, allowing for qualitative detection through visual inspection and quantitative measurement using ImageJ software. This method achieves the detection of miR-21 within a rapid 10-min timeframe, and the limit of detection (LOD) is 0.33pM. With the advantages of high specificity, simplicity, and sensitivity, the lateral flow test strip and the design strategy hold great potential for the early diagnosis of related diseases.

Bamboo leaf-derived biochar/iron silicate composite for an adsorption-degradation synergistic removal of ciprofloxacin

Antibiotics pose significant risks to both the environment and human health. Herein, we develop a collaborative strategy for the enhanced removal of a typical antibiotic, Ciprofloxacin (CIP), by using a bamboo leaf-derived biochar/iron silicate composite (BL-FeSi) with the assistance of peroxymonosulfate (PMS). The rationale behind the design is the construction of composited material with synergistic adsorption-catalysis functions, based on covalent bonding networks of the biochar and specific Fe(III)/Fe(II) redox chemistry of iron silicate in PMS activation system. H2 reduction of pristine BL-FeSi increases Fe(II) content and thus improves catalytic activity. Batch experiments demonstrate that the preferred BL-FeSi400 (H2 treatment at 400 °C) exhibits superior efficiency in activating PMS. The CIP removal efficiency is highly dependent on pH value of reaction solution. A remarkable 97% removal is achieved at pH = 5.5 (CIP: 60 mL, 20 mg/L; BL-FeSi400: 0.2 g/L, PMS: 0.2 g/L), and the pH increase to 11 results in 100% CIP removal. The BL-FeSi400 shows robust resistance to inorganic ions (NO3−, SO42−, HCO3−, and H2PO4−), and the catalytic activity remains consistently high (>82%) even after four consecutive cycles, making it highly promising for practical applications. It is found that both radical pathway (•OH and SO4•−) and non-radical pathway (1O2) contribute to CIP degradation in the BL-FeSi400/PMS system, while the active •OH dominates the oxidization process. The coupling of adsorption and degradation holds great potentials for effective removal of more organic contaminants.

Production of [211At]NaAt solution under GMP compliance for investigator-initiated clinical trial.

The alpha emitter astatine-211 (211At) is garnering attention as a novel targeted alpha therapy for patients with refractory thyroid cancer resistant to conventional therapy using beta emitter radioiodine (131I). Herein, we aimed to establish a robust method for the manufacturing and quality control of [211At]NaAt solution for intravenous administration under the good manufacturing practice guidelines for investigational products to conduct an investigator-initiated clinical trial. 211At was separated and purified via dry distillation using irradiated Bi plates containing 211At obtained by the nuclear reaction of 209Bi(4He, 2n)211At. After purification, the 211At trapped in the cold trap was collected in a reaction vessel using 15 mL recovery solution (1% ascorbic acid and 2.3% sodium hydrogen carbonate). After stirring the 211At solution for 1h inside a closed system, the reaction solution was passed through a sterile 0.22μm filter placed in a Grade A controlled area and collected in a product vial to prepare the [211At]NaAt solution. According to the 3-lot tests, decay collected radioactivity and radiochemical yield of [211At]NaAt were 78.8 ± 6.0 MBq and 40 ± 3%, respectively. The radiochemical purity of [211At]At- obtained via ion-pair chromatography at the end of synthesis (EOS) was 97 ± 1%, and remained > 96% 6h after EOS; it was detected at a retention time (RT) 3.2-3.3min + RT of I-. LC-MS analysis indicated that this principal peak corresponded with an astatide ion (m/z = 210.988046). In gamma-ray spectrometry, the 211At-related peaks were identified (X-ray: 76.9, 79.3, 89.3, 89.8, and 92.3keV; γ-ray: 569.7 and 687.0keV), whereas the peak at 245.31keV derived from 210At was not detected during the 22h continuous measurement. The target material, Bi, was below the 9 ng/mL detection limit in all lots of the finished product. The pH of the [211At]NaAt solution was 7.9-8.6; the concentration of ascorbic acid was 9-10mg/mL. Other quality control tests, including endotoxin and sterility tests, confirmed that the [211At]NaAt solution met all quality standards. We successfully established a stable method of [211At]NaAt solution that can be administered to humans intravenously as an investigational product.

Preparation technology comparison and performance evaluation of different protein A affinity chromatographic materials

Protein A affinity chromatographic materials are widely used in clinical medicine and biomedicine because of their specific interactions with immunoglobulin G (IgG). Both the characteristics of the matrix, such as its structure and morphology, and the surface modification method contribute to the affinity properties of the packing materials. The specific, orderly, and oriented immobilization of protein A can reduce its steric hindrance with the matrix and preserve its bioactive sites. In this study, four types of affinity chromatographic materials were obtained using agarose and polyglycidyl methacrylate (PGMA) spheres as substrates, and multifunctional epoxy and maleimide groups were used to fix protein A. The effects of the ethylenediamine concentration, reaction pH, buffer concentration, and other conditions on the coupling efficiency of protein A and adsorption performance of IgG were evaluated. Multifunctional epoxy materials were prepared by converting part of the epoxy groups of the agarose and PGMA matrices into amino groups using 0.2 and 1.6 mol/L ethylenediamine, respectively. Protein A was coupled to the multifunctional epoxy materials using 5 mmol/L borate buffer (pH 8) as the reaction solution. When protein A was immobilized on the substrates by maleimide groups, the agarose and PGMA substrates were activated with 25% (v/v) ethylenediamine for 16 h to convert all epoxy groups into amino groups. The maleimide materials were then converted into amino-modified materials by adding 3 mg/mL 3-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS) dissolved in dimethyl sulfoxide (DMSO) and then suspended in 5 mmol/L borate buffer (pH 8). The maleimide groups reacted specifically with the C-terminal of the sulfhydryl group of recombinant protein A to achieve highly selective fixation on both the agarose and PGMA substrates. The adsorption performance of the affinity materials for IgG was improved by optimizing the bonding conditions of protein A, such as the matrix type, matrix particle size, and protein A content, and the adsorption properties of each affinity material for IgG were determined. The column pressure of the protein A affinity materials prepared using agarose or PGMA as the matrix via the maleimide method was subsequently evaluated at different flow rates. The affinity materials prepared with PGMA as the matrix exhibited superior mechanical strength compared with the materials prepared with agarose. Moreover, an excellent linear relationship between the flow rate and column pressure of 80 mL/min was observed for this affinity material. Subsequently, the effect of the particle size of the PGMA matrix on the binding capacity of IgG was investigated. Under the same protein A content, the dynamic binding capacity of the affinity materials on the PGMA matrix was higher when the particle size was 44-88 μm than when other particle sizes were used. The properties of the affinity materials prepared using the multifunctional epoxy and maleimide-modified materials were compared by synthesizing affinity materials with different protein A coupling amounts of 1, 2, 4, 6, 8, and 10 mg/mL. The dynamic and static binding capacities of each material for bovine IgG were then determined. The prepared affinity material was packed into a chromatographic column to purify IgG from bovine colostrum. Although all materials showed specific adsorption selectivity for IgG, the affinity material prepared by immobilizing protein A on the PGMA matrix with maleimide showed significantly better performance and achieved a higher dynamic binding capacity at a lower protein grafting amount. When the protein grafting amount was 15.71 mg/mL, the dynamic binding capacity of bovine IgG was 32.23 mg/mL, and the dynamic binding capacity of human IgG reached 54.41 mg/mL. After 160 cycles of alkali treatment, the dynamic binding capacity of the material reached 94.6% of the initial value, indicating its good stability. The developed method is appropriate for the production of protein A affinity chromatographic materials and shows great potential in the fields of protein immobilization and immunoadsorption material synthesis.

Entire solutions with and without radial symmetry in balanced bistable reaction–diffusion equations

AbstractLet $$n\ge 2$$ n ≥ 2 be a given integer. In this paper, we assert that an n-dimensional traveling front converges to an $$(n-1)$$ ( n - 1 ) -dimensional entire solution as the speed goes to infinity in a balanced bistable reaction–diffusion equation. As the speed of an n-dimensional axially symmetric or asymmetric traveling front goes to infinity, it converges to an $$(n-1)$$ ( n - 1 ) -dimensional radially symmetric or asymmetric entire solution in a balanced bistable reaction–diffusion equation, respectively. We conjecture that the radially asymmetric entire solutions obtained in this paper are associated with the ancient solutions called the Angenent ovals in the mean curvature flows.

Surface-bound radicals enhancing detoxification of enrofloxacin during peroxymonosulfate oxidation: Activated carbon vs. alumina as catalyst carriers

Recent studies have found the presence of surface-bound radicals (Surf-R) during the heterogeneously catalyzed peroxymonosulfate (PMS), especially when the catalyst carriers possess a high adsorption capacity. However, the effects of Surf-R on the toxicity of transformation products (TPs) are still not well elucidated. In this study, Co and Mn were loaded onto commonly used carriers: activated carbon and alumina (CoMn@AC vs CoMn@Al2O3) to create comparable catalytic centers but distinct adsorption capacity, which was proved by material characterization (SEM, EDS, BET, XPS), adsorption and catalytic tests. Both images and quantitative analysis with 3D excitation-emission matrix fluorescence spectroscopy demonstrated that the reaction solutions of enrofloxacin from two catalysts composed differently when a same degradation efficiency was achieved. It was further found that the respiratory inhibition of CoMn@AC catalyzed samples was only 7–36% of the counterpart. 50 TPs were identified with UPLC-MS/MS, among which 31 TPs were possibly more toxic than enrofloxacin according to the calculation with the Toxicity Estimation Software Tool. CoMn@Al2O3 produced 14 unique toxic TPs while CoMn@AC only 4. The analysis with EPR revealed that both catalysts generated SO4•-, •OH, and 1O2; quenching tests proved a lot of Surf-R with CoMn@AC but not with CoMn@Al2O3. This study demonstrates the high potential of Surf-R to enhance the detoxification of organic contaminants during PMS oxidation and thus provides a reference for designing novel catalysts to achieve efficient contaminant degradation and detoxification.

Effect of small-molecule phenolic compounds on the removal of triclosan (TCS) by heat/persulfate process: Formation of cross-coupling products and implications for wastewater treatment

In this study, the effect of three small molecule phenolic compounds (SMPCs) (Phenol (PHOH), p-hydroxybenzoic acid (PHBA) and 3,5-dihydroxytoluene (DHT)) on the transformation of triclosan (TCS) in heat activated persulfate (heat/PS) process was investigated. TCS in single and mixed solutions were almost completely removed after 120 min of heat/PS treatment. Compared with single TCS system, the generation of cross-coupling products in the mixed system was beneficial for the removal of total organic carbon (TOC). Overall cytotoxicity and genotoxicity tests on mammalian cells showed that the reaction products in mixed phenol system was less toxic than those in the single TCS system, which confirmed the low toxicity of cross-coupling products. Product analysis was combined with theoretical calculations to propose a mechanism for the cross-coupling of coexisting phenolic pollutants that hydrogen on the phenolic hydroxyl groups of different pollutants was extracted by SO4•- to form phenoxy radicals, which coupled with each other to form cross-coupling products. Lowering the pH of the reaction solution can promote the occurrence of cross-coupling reaction, favoring the removal of TOC and the reduction of toxicity. These results will provide insights into the transformation of phenolic pollutants in water treatment for further control of environmental risks.

Reaction solution mediated photo-degradation process and mechanism of tetracycline via semiconductor-insulator composite ZnO:N-BaSO4

Research in contaminants photo-degradation has witnessed significant progress, recently insulator-based catalysts gaining prominence. In this study, N-containing p-type ZnO decorated BaSO4 (ZnO:N-BaSO4) were synthesized and presented a pseudo-first-order kinetic constant of 1.30 × 10−2 min−1 for TC degradation, surpassing that of ZnO:N and their physical mixture by four and seven-fold, respectively. Impressively, the electron transfer in ZnO:N/TC solution interface led to band bending on ZnO:N surface and realized the band matching between ZnO:N and BaSO4. Density functional theory (DFT) calculations unveiled that the strong Zn-O covalent interaction involving 4s states of Zn atoms and 2p states of O atoms, established a distinctive pathway for electron transfer from semiconductor to insulator. Moreover, the catalysts demonstrated robust activity and sustained long-term stability in real wastewater and surface water. This research illuminates the role of wastewater redox potential in semiconductor band adjustment and highlights abundant, eco-friendly insulators as co-catalysts for selective photo-degradation.

Preparation of a macroporous anion exchange chromatographic medium by polyamine grafting and evaluation of its protein-adsorption behavior

The macroporous anion exchange chromatographic medium (FastSep-PAA) was prepared through grafting polyallylamine (PAA) onto polyacrylate macroporous microspheres (FastSep-epoxy). The effects of the synthesis conditions, including the PAA concentration, reaction time, and reaction solution pH, on the ion exchange (IC) of the medium were investigated in detail. When the PAA concentration, reaction time, and reaction solution pH were increased, the IC of the medium increased, and optimal synthesis conditions were then selected in combination with changes of protein binding capacity. A scanning electron microscope was used to examine the surface morphology of the medium. The medium possessed high pore connectivity. Furthermore, the pore structure of the medium was preserved after the grafting of PAA onto the macroporous microspheres. This finding demonstrates that the density of the PAA ligands does not appear to have any discernible impact on the structure of the medium; that is, no difference in the structure of the medium is observed before and after the grafting of PAA onto the microspheres. The pore size and pore-size distribution of the medium before and after grafting were determined by mercury intrusion porosimetry and the nitrogen adsorption method to investigate the relationship between pore size (measured in the range of 300-1000 nm) and protein adsorption. When the pore size of the medium was increased, its protein binding capacity did not exhibit any substantial decrease. An increase in pore size may hasten the mass transfer of proteins within the medium. Among the media prepared, that with a pore size of 400 nm exhibited the highest dynamic-binding capacity (DBC: 70.3 g/L at 126 cm/h). The large specific surface area of the medium and its increased number of protein adsorption sites appeared to positively influence its DBC. When the flow rate was increased, the protein DBC decreased in media with original pore sizes of less than 700 nm. In the case of the medium with an original pore size of 1000 nm, the protein DBC was independent of the flow rate. The protein DBC decreased by 3.5% when the flow rate was increased from 126 to 628 cm/h. In addition, the protein DBC was maintained at 57.7 g/L even when the flow velocity was 628 cm/h. This finding reveals that the diffusion rate of protein molecules at this pore size is less restricted and that the prepared medium has excellent mass-transfer performance. These results confirm that the macroporous polymer anion exchange chromatographic medium developed in this study has great potential for the high-throughput separation of proteins.

Hydrophobization of surfaces on cellulose nanofibers by enzymatic grafting of partially 2-deoxygenated amylose

Recently, attention has been paid to cellulose nanofibers, such as 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibers (TOCN), as new bio-based materials. In addition, hydrophobized surface on TOCNs can be expected to provide new applications. Based on our previous finding that partially 2-deoxygenated (P2D)-amylose, which was synthesized by GP-catalyzed enzymatic copolymerization of D-glucal with α-d-glucose 1-phosphate (Glc-1-P) as comonomers, was hydrophobic, in this study, hydrophobization of surfaces on TOCNs was investigated by the GP-catalyzed enzymatic grafting of P2D-amylose chains on TOCNs. After maltooligosaccharide primers were modified on TOCNs, the GP-catalyzed enzymatic copolymerization of D-glucal with Glc-1-P was performed for grafting of P2D-amylose chains. 1H NMR spectroscopic analysis confirmed the production of P2D-amylose-grafted TOCNs with different 2-deoxyglucose/Glc unit ratios. The powder X-ray diffraction profiles of the products indicated that the entire crystalline structures were strongly affected by the unit ratios and chain lengths of the grafted polysaccharides. The SEM images observed differences in nanofiber diameter in the reaction solutions and surface morphology after film formation, due to grafting of P2D-amylose chains from TOCNs. The water contact angle measurement of a cast film prepared from the product indicated its hydrophobicity.

Efficient synthesis of tricaproin: catalyst and reaction optimization

Abstract This study presents a short communication on exploring, for the first time, a simple approach for the selective and highly effective synthesis of tricaproin by synergistically combining silicon tripolyphosphate and phosphoric acid in the catalytic esterification of glycerol with caproic acid. Results reveal that within the initial hour of the synthesis, the conversion in the presence of the proposed mixture achieved an efficiency of 62.99 %, whereas this figure for individual catalysts only modestly stopped at 27.50 and 11.74 %, respectively. Furthermore, the inherent shortcomings in the tricaprion synthesis, such as catalyst deactivation, resinification of the reaction solution, and generation of numerous by-products, were successfully addressed. The structure of the resultant tricaproin and the possible absence of undesired by-products were confirmed by NMR, mass spectrometry, FT-IR, and TLC. The optimal conditions for the synthesis were also investigated. The study not only contributes a practical and selective synthetic approach for tricaproin but also paves the way for exploring novel avenues to enhance the efficiency of the catalytic esterification.

Adsorption/photocatalytic degradation of Cefixime by the green Bi2WO6/g-C3N4/ZIF-67 dual S-scheme heterojunction: Artificial neural network, genetic algorithm, density functional theory, and toxicity assessments

This study investigated the photocatalytic adsorption, degradation, and mineralization of Cefixime (CFX) through hydrothermally synthesized Bi2WO6(36 %)/g-C3N4(54 %)/ZIF-67(10 %) dual S-scheme heterojunction (BCZ). Full characterization analysis for the fresh and reused photocatalyst was explored to study the formation of heterojunction, stability, and reusability of the BCZ. VB-XPS, Mott-Schottky plots, and UV–Vis DRS defined the band structure and electron transfer mechanism of BCZ. The effects of ten operating condition factors, including reaction time, initial concentration of CFX, the dosage of photocatalyst, reaction temperature, initial pH of the reaction, visible and UV intensity, and concentration of Na2SO4, NaOH, and NaCl in the reaction solution were experimentally investigated. These factors were then modeled through artificial neural networks (ANN). The number of neurons, training algorithm, and the type of activation functions in the ANN were optimized by mean squared error metric followed by the visualizations of the ANN predictions. Two cost functions (the ratio of instantaneous CFX concentration to initial CFX concentration (C/C0) and the ratio of photocatalyst dosage to the amount of CFX removed) were employed to optimize the value of these operating condition factors separately and simultaneously through single and multi-objective genetic algorithms. Coupling LC-MS results and DFT calculations, a degradation pathway for Cefixime was proposed and then analyzed by QSAR. The toxicity of the treated solution was investigated using the wheat seed culture, along with MIC and MBC testing conducted by E. coli and S. aureus, and its eco-friendliness was confirmed by TOC and COD. Furthermore, ICP-OES confirmed that BCZ is a green photocatalyst.

Porous Anisometric PNIPAM Microgels: Tailored Porous Structure and Thermal Response.

The porous structure of microgels significantly influences their properties and, thus, their suitability for various applications, in particular as building blocks for tissue scaffolds. Porosity is one of the crucial features for microgel-cell interactions and significantly increases the cells' accumulation and proliferation. Consequently, tailoring the porosity of microgels in an effortless way is important but still challenging, especially for nonspherical microgels. This work presents a straightforward procedure to fabricate complex-shaped poly(N-isopropyl acrylamide) (PNIPAM) microgels with tuned porous structures using the so-called cononsolvency effect during microgel polymerization. Therefore, the classical solvent in the reaction solution is exchanged from water to water-methanol mixtures in a stop-flow lithography process. For cylindrical microgels with a higher methanol content during fabrication, a greater degree of collapsing is observed, and their aspect ratio increases. Furthermore, the collapsing and swelling velocities change with the methanol content, indicating a modified porous structure, which is confirmed by electron microscopy micrographs. Furthermore, swelling patterns of the microgel variants occur during cooling, revealing their thermal response as a highly heterogeneous process. These results show a novel procedure to fabricate PNIPAM microgels of any elongated 2D shape with tailored porous structure and thermoresponsiveness by introducing the cononsolvency effect during stop-flow lithographypolymerization.

Aquatic photolysis of high-risk fluorinated liquid crystal monomers: Kinetics, toxicity evaluation, and mechanisms

Despite the frequent detection of fluorinated liquid-crystal monomers (FLCMs) in the environment, the level of understanding of their fate, toxicity, and transformation remains insufficient. Herein, we investigated the degradation kinetics and mechanism of an FLCM (4-cyano-3-fluorophenyl 4-ethylbenzoate, CEB-F) under ultraviolet (UV) photolysis in aquatic environment. Our findings demonstrated that the UV photolysis of CEB-F followed first-order kinetics. Photodegradation products were identified using liquid chromatography with mass spectrometry, and detailed reaction pathways were proposed. It is postulated that through the attack of reactive oxygen species, hydroxylation, and CO/C-F bond cleavage, CEB-F gradually degraded into small molecular compounds, releasing fluorine ions. Acute immobilization tests with Daphnia magna (D. magna) revealed significant acute toxicity of CEB-F, with LC50 values ranging from 1.023 to 0.0536 μM over 24 to 96 h, emphasizing the potential high risk of FLCMs in aquatic ecosystems if inadvertently discharged. Interestingly, we found that the toxicity of CEB-F photolysis reaction solutions was effectively reduced. Through catalase and acetylcholinesterase activities analysis along with molecular docking simulation, we proposed differences in the underlying toxicity mechanisms of CEB-F and its photolysis products to D. magna. These findings highlight the potential harmful effects of FLCMs on aquatic ecosystems and enrich our understanding of the photolysis behavior of FLCMs.

Development of Green and High-Throughput Microwell Spectrophotometric Methods for Determination of Galidesivir in Bulk Drug and Dosage Forms Based on Simple Oxidimetric Reactions With Inorganic Agents.

Galidesivir hydrochloride (GDV) is a new potent and safe antiviral drug used for the treatment of a broad spectrum of viral diseases, including COVID-19. In the literature, no analytical method exists for the determination of GDV in bulk or dosage form. The objective of this study was the investigation of oxidation reactions of GDV with five inorganic oxidizing reagents and the employment of the reactions in the development of five green microwell spectrophotometric methods (MW-SPMs) with simple procedure and high throughputs for determination of GDV in its bulk and dosage forms (capsules). The reactions were carried out in 96-well plates, and the absorbances of reaction solutions were measured by an absorbance microplate reader. Variables influencing the reactions were carefully investigated and optimized. Under the refined optimum conditions, Beer's law with excellent correlation coefficients (0.9992-0.9997) was followed in GDV concentrations in a general range of 5-700 µg/mL, and the limits of detection were ≥1.8 µg/mL. All validation parameters of all methods were acceptable. The methods were successfully applied to the analysis of GDV in bulk drug and capsules with high accuracy and precision; the recovery percentages were 98.6-101.2 ± 0.58-1.14%. The greenness of MW-SPMs was evaluated by three comprehensive metric tools, which demonstrated the adherence of MW-SPMs to the principles of the green analytical chemistry (GAC) approach. The proposed MW-SPMs combined the advantages of microwell-based practice and the use of common laboratory reagents for the analysis. The advantages of microwell analysis were the high throughput, readily available for semi-automation, reduced samples/reagents volume, precise measurements, and versatility. The advantages of using common laboratory reagents were the availability, consistency, compatibility, safety, and cost-effectiveness. Overall, the proposed MW-SPMs are versatile, valuable tools for the quantitation of GDV during its pharmaceutical manufacturing.