Optimal Reaction Conditions Research Articles

PEG modification increases thermostability and inhibitor resistance of Bst DNA polymerase.

Polyethylene glycol modification (PEGylation) is a widely used strategy to improve the physicochemical properties of various macromolecules, especially protein drugs. However, its application in enhancing the performance of enzymes for molecular biology remains underexplored. This study explored the PEGylation of Bst DNA polymerase, determining optimal modification reaction conditions. In comparison to the unmodified wild-type counterpart, the modified Bst DNA polymerase exhibited significantly improved of activity, thermal stability and inhibitor tolerance during loop-mediated isothermal amplification (LAMP). When applied for the detection of Salmonella in crude samples, the modified enzyme demonstrated a notably accelerated reaction rate. Therefore, PEGylation emerges as a viable strategy for refining DNA polymerases, helping in the development of novel molecular diagnostic reagents.

In Situ Carbon-Confined MoSe2 Catalyst with Heterojunction for Highly Selective CO2 Hydrogenation to Methanol

The synthesis of methanol from CO2 hydrogenation is an effective measure to deal with global climate change and an important route for the chemical fixation of CO2. In this work, carbon-confined MoSe2 (MoSe2@C) catalysts were prepared by in situ pyrolysis using glucose as a carbon source. The physico-chemical properties and catalytic performance of CO2 hydrogenation to yield methanol were compared with MoSe2 and MoSe2/C. The results of the structure characterization showed MoSe2 displayed few layers and a small particle size. Owing to the synergistic effect of the Mo2C-MoSe2 heterojunction and in situ carbon doping, MoSe2@C with a suitable C/Mo mole ratio in the precursor showed excellent catalytic performance in the synthesis of methanol from CO2 hydrogenation. Under the optimal catalyst MoSe2@C-55, the selectivity of methanol reached 93.7% at a 9.7% conversion of CO2 under optimized reaction conditions, and its catalytic performance was maintained without deactivation during a continuous reaction of 100 h. In situ diffuse infrared Fourier transform spectroscopy studies suggested that formate and CO were the key intermediates in CO2 hydrogenation to methanol.

Study on Catalytic Activity of Synthetic Cobalt, Nickel and Copper Complexes due to Preferred Structures Determined by X‐Ray Crystallography for Methyl Methacrylate Polymerization

AbstractWe have designed and synthesized two novel pyridyl‐quinoxaline ligands, L1 and L2, as well as twelve cobalt, nickel, and copper complexes, 1–6 and 1 a–6 a. Unexpectedly, high regularities in the synthesis of both ligands and complexes were found. Further X‐ray diffraction analyses revealed that the two ligands had similar geometrical configurations, and the structures of twelve complexes were regularly divided into two categories: binuclear and mononuclear, which would be beneficial for elucidating structure‐activity relationships of metal catalysts. In addition, the experimental results showed significant variations in the catalytic performance of methyl methacrylate polymerization with different catalysts. Under the optimum reaction conditions, the mononuclear copper complex 3 a displayed a remarkably high catalytic activity of 2.76×105 g ⋅ mol−1 h−1, generating Poly(methyl methacrylate) with molecular weight of Mn=8.55×105 g ⋅ mol−1 and molecular weight distribution of Đ=1.67.This outcome suggested that copper had the potential to serve as a promising catalytic metal center.

Enantioselective Silylative Desymmetrization of meso-Indane-1,3-diols Catalyzed by Chiral Guanidines

Chiral guanidine-catalyzed desymmetrization of meso-indan-1,3-diols was achieved via enantioselective silylation by using chlorosilanes in good yields with high selectivity. The combination of chlorosilanes and catalysts was determined by the substituents at the C-2 position on the substrate. It was found that the fused phenyl ring on the substrate was essential for achieving high selectivity. The proposed method was found to be applicable to several types of substrates under optimized reaction conditions. Double silylative kinetic resolution with additive Horeau amplification was observed to establish high selectivity.

In-silico-assisted derivatization of triarylboranes for the catalytic reductive functionalization of aniline-derived amino acids and peptides with H2

Cheminformatics-based machine learning (ML) has been employed to determine optimal reaction conditions, including catalyst structures, in the field of synthetic chemistry. However, such ML-focused strategies have remained largely unexplored in the context of catalytic molecular transformations using Lewis-acidic main-group elements, probably due to the absence of a candidate library and effective guidelines (parameters) for the prediction of the activity of main-group elements. Here, the construction of a triarylborane library and its application to an ML-assisted approach for the catalytic reductive alkylation of aniline-derived amino acids and C-terminal-protected peptides with aldehydes and H2 is reported. A combined theoretical and experimental approach identified the optimal borane, i.e., B(2,3,5,6-Cl4-C6H)(2,6-F2-3,5-(CF3)2-C6H)2, which exhibits remarkable functional-group compatibility toward aniline derivatives in the presence of 4-methyltetrahydropyran. The present catalytic system generates H2O as the sole byproduct.

Cu(I)‐Catalyzed Coupling Reactions of β‐Nitrostyrene, 1,3‐Dicarbonyl compound & Aryl amine: An Efficient Method For the Synthesis of Polysubstituted Pyrroles

AbstractA convenient Cu(I) Catalyzed three‐component coupling strategy for the synthesis of polysubstituted pyrroles is developed using simple and readily available building blocks like, 1, 3‐dicarbonyl compound, aryl amine, and β‐nitrostyrene. CuI has been rarely explored for the pyrrole ring synthesis and a comparative analysis of our current catalyst with a range of previously reported catalysts suggested that, CuI is one of the best catalysts for the multicomponent synthesis of polysubstituted pyrrole derivatives. Notably, this process has several advantages, including a simple and practical set‐up with hassle free reaction conditions, extensive substrate scope, short reaction time, high atom economy and environmentally favorable approach. This methodology provides an alternative approach to the highly substituted pyrroles and under optimized reaction conditions, polysubstituted pyrroles were formed in good to excellent yields. Cu(I) catalyzed Mannich reactions followed by Michael addition reactions along with subsequent intramolecular cyclization are believed to be the key steps of this reaction process.

Thermodynamic and environmental analysis of integrated supercritical water gasification of sewage sludge for power and hydrogen production

Supercritical water gasification is a promising process for treating sewage sludge (SS) to obtain hydrogen and electrical energy. Here, a novel thermodynamic equilibrium model for supercritical water gasification of sewage sludge was developed and the thermodynamic and environmental effects of operating parameters on the system were investigated. The sensitivity analysis revealed that the optimum reaction condition for the system was: reaction temperature of 750 °C, preheated water to SS ratio of 1, and SS concentration of 25 %. Under this condition, the system energy efficiency and exergy efficiency were 44.74 % and 46.51 %, respectively, with H2 production of 103.19 kg/h and power generation of 2526.2 kW. The energy and exergy efficiencies could be improved by reducing the preheated water to SS ratio and increasing the reaction temperature and SS concentration. The heat exchangers and the heater were the key units causing exergy losses, accounting for 40.3 % and 19.5 % of the total exergy losses, respectively. When utilizing carbon capture and storage (CCS), the global warming potential (GWP) value was only 0.31 kg CO2-eq under the optimal operating parameters, which was 61.44 % less than without CCS.

Green synthesized AgNPs as a probe for colorimetric detection of Hg (II) ions in aqueous medium and fluorescent imaging in liver cell lines and its antibacterial activity

The present research aimed at green synthesis of Ag nanoparticles (AgNPs) based colorimetric sensor using persimmon leaf extract (PLE) for selective detection of mercuric ion (Hg2+). Optimization of reaction conditions viz. pH, concentration of PLE, time was done and further AgNPs were characterized using UV, IR, FE-SEM, EDX, XRD and TEM analysis. The developed AgNPs were evaluated for the selective colorimetric detection of Hg2+ in aqueous medium and fluorescence imaging of Hg2+ ions in liver cell lines. Later, the antibacterial activity of AgNPs was performed against S. aureus and E. coli. The findings of the study revealed that PLE mediated AgNPs exhibited notable limit of detection up to 0.1 ppb, high efficiency, and stability. The antibacterial study indicated that developed AgNPs has impressive bacterial inhibiting properties against the tested bacterial strains. In conclusion, developed biogenic AgNPs has high selectivity and notable sensitivity towards Hg2+ ions and may be used as key tool water remediation.Graphical abstract

Kinetic Resolution of Cyclic Tertiary Alcohols with Lipase A from Candida Antarctica

AbstractEnzyme‐catalyzed acylative kinetic resolution (KR) and dynamic kinetic resolution (DKR) of racemic primary and secondary alcohols have been widely reported to produce esters with high enantiomeric purity. In contrast, similar KRs of tertiary alcohols have been reported for only a limited range of substrates and require prolonged reaction times of several days. To gain deeper insight into the substrate scope and increase the process efficiency, we examined the reaction conditions using commercially available immobilized lipase A from Candida antarctica and found that the addition of the heterogeneous, inorganic base sodium carbonate significantly increased the reaction rate while maintaining high enantioselectivity. The use of vinyl hexanoate as the acyl donor provided esters that were stable during chromatography purification. The optimized reaction conditions were then successfully applied to a range of cyclic tertiary alcohols containing tetralin, dihydroindene, chromane, and thiochromane skeletons having, in part, a substituent on the aromatic ring. In this study on the structure–reactivity relationship of enzymatic KR‐type reactions, we achieved >30 % conversion for various tertiary alcohols in 24 h at 25 °C, producing optically active esters with 88–99 % ee.

Microwave responsive copper-ferrite (CuFe2O4) encapsulated in molybdenum-disulfide (MoS2) nanoflower catalyst for antibiotic removal via persulfate oxidation

Microwave (MW) responsive copper-ferrite/molybdenum-disulfide (CuFe2O4/MoS2) nanoflower catalyst was implemented for rapid antibiotic metronidazole (MNZ) degradation via persulfate oxidation under MW irradiation. The catalyst was synthesized via co-precipitation followed by hydrothermal methods, and characterized by XRD, FTIR, SEM, TEM, VSM, XPS, and UV-DRS. As a first step, MW induced MNZ removal was studied at different initial mass of CuFe2O4/MoS2 (2.5–20%), where 5% CuFe2O4 in the nanocomposite performed the best. Within 5 min of MW irradiation, 100% MNZ removal was observed (Kobs ∼ 1.063 min−1) under the optimal reaction conditions (i.e., CuFe2O4/MoS2 dose ∼ 0.4 g/L; PS dose ∼ 100 mg/L; temperature ∼ 90 °C; and MW power ∼ 350 W). The MNZ removal was independent of solution pH 3–11, and the removal was by SO4•−and •OH radicals alongside the limited contribution from O2•−. PS and H2O were thermally decomposed to produce SO4•−and •OH radicals, whereas intrinsic semiconductor CFO/MS with a narrow bandgap of 1.53 eV allowed electrons to jump into conduction band from valance band to create SO4•− and O2•−. However, the performance of MW system was inhibited by the presence of anions in the order of Cl−< NO3− <CO32− <H2PO4−. Robustness of the CuFe2O4/MoS2 was proved via recyclability experiments, and MNZ removal was found to be dropped ∼ 4.89% at the end of 5th cycle. It was proposed that the absorbed MW energy was dissipated through various losses to generate ‘hotspots’ (>1200 °C) for MNZ removal. Synergistically, redox couples of transitional metals contributed to MNZ degradation.

Preparation CaO/MgO/Fe3O4 magnetite catalyst and catalytic test for biodiesel production

Biodiesel is a promising renewable fuel with lower emissions and environmental friendly. This research investigated the potential of a CaO/MgO/Fe3O4 nanomagnetic catalyst synthesized from dolomite and iron sand for biodiesel production from waste cooking oil. The influence of catalyst loading, Fe3O4:CaO/MgO mass ratio, and calcination temperature on biodiesel yield was investigated and the catalyst was characterized using XRD, SEM, and PSA techniques. The optimal reaction conditions were found at 1 % w/w catalyst loading, Fe3O4:CaO/MgO weight ratio of 1:7.5 w/w, and 1000 °C calcination temperature, which result in 95.640 % yield. The produced biodiesel has fulfill the quality standards for density and viscosity. This work also demonstrates the effectiveness of CaO/MgO/Fe3O4 nanomagnetic catalysts for sustainable biodiesel production from waste feedstock, offering a promising approach for waste management and cleaner fuel alternatives.

A novel signal amplified sandwich aptamer-based visual lateral flow assay based on self-assembly bifunctional nucleic acid for rapid and sensitive detection of CKMB

At present, rapid and sensitive detection of disease biomarkers is still the focus of early clinical diagnosis. As a rapid response to point-of-care testing (POCT), lateral flow assay (LFA) has been given serious attention. Unfortunately, due to the sensitivity limitations, LFA, especially AuNPs-based LFA, was difficult to play an important role in the detection of trace biomarkers. The combination of different signal amplification methods increases the complexity of operation and use, or prolongs the detection time, which sacrifices the advantages of fast and convenient of LFA. Hence, a novel sandwich aptamer-based visual LFA based on bifunctional nucleic acid (bFNA-LFA) was proposed for rapid and sensitive detection of creatine kinase MB (CKMB) in this study. Based on hybridization chain reaction (HCR) and nucleic acid hybridization, a bifunctional nucleic acid with target recognition and signal amplification was prepared, which effectively improved the sensitivity of CKMB detection without increasing the reaction time and depending on the detecting equipment. Under optimal reaction conditions, the limit of detection of 7.92 ng/mL was observed, which was 20 times lower than that of sandwich aptamer-based AuNPs LFA in the previous study. The proposed bFNA-LFA assay expanded a new idea in improving the sensitivity of LFA, and provided a reference for the subsequent application of nucleic acid nanomaterials in the detection of protein biomarkers.

Engineering a staggered type-II Bi2WO6/WO3 heterojunction with improved photocatalytic activity in wastewater treatment

In recent years, the removal organic pollutants from wastewater by advanced oxidation processes, especially photocatalysis, has become a meaningful approach due to its eco-friendliness and low cost. Herein, staggered type-II Bi2WO6/WO3 heterojunction photocatalysts were prepared by a facile hydrothermal route and investigated by modern physicochemical methods (X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption-desorption, and diffuse reflectance spectroscopy). The optimized BWOW-5 photocatalyst exhibited a H2O2-assisted photocatalytic methylene blue removal efficiency of 94.1% (k = 0.01414 min–1) within 180 min under optimal reaction conditions, which is much higher than that of unmodified Bi2WO6 and WO3 due to efficient separation of the photogenerated charge carriers. The trapping experiments demonstrate that photogenerated hydroxyl radicals and holes plays a key role in the photodegradation reaction. Moreover, the optimized BWOW-5 heterojunction photocatalyst exhibited excellent activity in the H2O2-assisted degradation of other pollutants, namely phenol, isoniazid, levofloxacin, and dibenzothiophene with the removal rate of 63.1, 73.6, 95.0, and 72.4%, respectively. This investigation offers a design strategy for Bi2WO6-based multifunctional photocatalytic composites with improved activity for organic pollutant degradation.

Assessment of the strength of Grignard Reagent for the synthesis of secondary and tertiary alcohols of terpenes using metal plate flow reactor

The secondary and tertiary alcohols of terpenes were synthesized from aldehydes, and ketones using allyl magnesium chloride by the continuous metal flow reactor method. The flow process was conducted using metal plate reactors of 10 ml capacity in the presence of solvent mixtures, instead of large amounts of pure solvent like tetrahydrofuran. The products were isolated, and confirmed using gas chromatography and Nuclear magnetic resonance techniques respectively. Subsequently, the optimization studies were conducted to obtain mild, and economical reaction conditions, by varying the amount of allyl magnesium chloride, temperature, pressure, retention time, and flow rates. A comparison between batch processes and flow processes proved the advantages of the flow process in terms of reproducibility and product yield without the requirement of excess reagents compared to the batch process. The product yield was found to be excellent (60-97%) and reproducible at (1-50) gram scale through flow process. The scope of the reaction was studied by synthesizing terpene alcohols using different carbonyl compounds at optimized reaction conditions, which resulted in high product yield. This research addresses a crucial gap in terpene alcohol synthesis, offering a scalable and environmentally friendly approach with broad applicability.

α-Zr(HPO4)2·H2O: As an effective and recoverable catalyst for the synthesis of a family of quinoxalines in semi-aqueous conditions

In our work, we have established a straightforward and friendly process for the preparation of a family of quinoxaline. This method relies on using α-Zr(HPO4)2·H2O as a catalyst and an ethanol/water mixture as an ecological solvent. Firstly, we prepared α-Zr(HPO4)2·H2O by a simple hydrothermal procedure and conducted comprehensive characterization employing various analytical methods. On the other hand, we produced the quinoxalines by means of a condensation reaction between 1,2-dicarbonyl compounds and various 1,2-diamines. The synthesized quinoxaline and its derivative products were characterized by melting point, proton, and carbon nuclear magnetic resonance analysis. As a result, the optimal reaction conditions that resulted in a high yield (97–98 %) were an amount of catalyst of 0.03 g, a stirring time of 8 min, a volume of solvent of 2 mL, and a reaction temperature of 50 °C. This approach is advantageous due to its simple and eco-friendly procedure, green solvent, quick reaction time, low cost, and high yields. Additionally, it offers the possibility to recycle the catalyst for a minimum of five cycles with no decrease in its catalytic activity.

One-step triplex TaqMan quantitative reverse transcription polymerase chain reaction for the detection of feline coronavirus, feline panleukopenia virus, and feline leukemia virus

Background and Aim: Feline coronavirus (FCoV), feline panleukopenia virus (FPV), and feline leukemia virus (FeLV) are prevalent throughout China and significantly threaten cat health. These viruses cause similar manifestations and pathological damage. Rapid and accurate diagnosis depends on detection in the laboratory. This study aimed to establish a reliable and rapid method for accurate detection of FCoV, FPV, and FeLV so that a definite diagnosis can be made and effective measures can be taken to prevent and control viral infection. Materials and Methods: We designed three pairs of specific primers and probes for the detection of FCoV 5′ untranslated region, FPV viral protein 2, and FeLV pol genes. Recombinant plasmid constructs were generated for use as standard plasmid constructs. Optimal reaction conditions, including primer and probe concentrations, reaction cycles, and annealing temperatures, were obtained on the basis of optimization tests. One-step triplex real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was successfully established to simultaneously detect FCoV, FPV, and FeLV. The specificity, sensitivity, and repeatability of the assay were analyzed, and its applicability was validated by testing 1175 clinical samples. Results: One-step triplex RT-qPCR had a high degree of specificity only for the detection of FCoV, FPV, and FeLV; it had high sensitivity with limits of detection of 139.904, 143.099, and 152.079 copies/reaction for p-FCoV, p-FPV, and p-FeLV standard plasmid constructs, respectively, and it had reliable repeatability with 0.06%–0.87% intra-assay coefficients of variations. A total of 1175 clinical samples were examined for FCoV, FPV, and FeLV using triplex RT-qPCR, and the FCoV, FPV, and FeLV positivity rates were 18.47%, 19.91%, and 47.57%, respectively. The clinical sensitivity and specificity of one-step triplex RT-qPCR were 93.07% and 97.99%, respectively. Conclusion: We developed a rapid and reliable one-step triplex RT-qPCR method for the detection of FCoV, FPV, and FeLV, which could be used as a diagnostic tool for clinical monitoring and diagnosis. Keywords: detection method, feline coronavirus, feline leukemia virus, feline panleukopenia virus, multiplex reverse transcription-quantitative polymerase chain reaction.

Remediation of petroleum hydrocarbon contaminated soils by nZVI coupled with electrokinetic activation of persulfate

This paper explores the use of nanoscale zero-valent iron (nZVI) coupled with electrically activated persulfate (nZVI-EK/PS) for remediating petroleum hydrocarbon-contaminated soil. The effects of persulfate (PS) dosage, nZVI dosage, and soil organic matter content on the remediation of petroleum hydrocarbons were investigated. The study concludes that persulfate (PS) and nanoscale zero-valent iron (nZVI) are the primary factors influencing the remediation of petroleum hydrocarbons in the nZVI-EK/PS system. The optimal reaction conditions of PS = 170 mmol and nZVI = 17 mmol increased the efficiency of petroleum hydrocarbon treatment to 40.45%, with the highest removal efficiency of petroleum hydrocarbons observed at position S2, reaching 48.5%. With the addition of organic matter at 5%, the efficiency of petroleum hydrocarbon treatment reached 50.08%, representing a 9.68% enhancement in the nZVI-EK/PS system. Furthermore, potential mechanisms for the degradation of petroleum hydrocarbons by the nZVI-EK/PS system were identified using gas chromatography-mass spectrometry (GC-MS). The degradation order of different components was found to be esters < alkenes < alkanes < phenols.

Catalytic Cracking of Oily Sludge using Nickel Metal Catalyst Embedded in Silica Derived from Adsorbent in a Gas Process Plant

Abstract. One of the Oily Sludge (OS) recycling methods is through catalytic cracking. This process involves the reaction breaking down large molecules into smaller ones with the help of a catalyst. Nickel (Ni) metal is often used as a catalyst because it can increase fuel liquid yield while reducing the coke formation. To enhance its performance, Ni metal can be embedded in a carrier material like Silica to form the Ni-Silica catalyst. In this research, OS sourced from a Gas Process Plant is treated with catalytic cracking using Ni-Silica, where the Silica used is derived from an Adsorbent activated with NaOH. Optimization of the cracking conditions is carried out using Response Surface Methodology (RSM) with a Box-Behnken design. The optimized cracking reaction conditions include temperature (713 K, 723 K, and 733 K), time (50 min, 60 min, and 70 min), and catalyst-to-OS ratio of 1:5, 1:6, and 1:7. Statistical analysis indicates that the relationship between the reaction condition variables and the Oil Liquid Product (OLP) falls into the moderate category, as shown by the coefficient of determination (R²) of 0.5. The calculated F-value for the deviation from the mathematical model is smaller than the F-Table value (9.2) at both 5% and 1% significance levels, with a value of 0.6. This indicates that the mathematical model generated can be accepted as the mathematical model within the range of reaction conditions in this study. Calculus analysis reveals that the optimum reaction conditions are a temperature of 717.34 K, a time of 58.58 min, and a catalyst-to-OS ratio of 1:6, 15. Canonical analysis indicates that for OLP, λ1= [-12.38], λ2= [-2.27], and λ3= [4.50], where lambda values indicate that the most sensitive response surface parameter for OLP is temperature, followed by the catalyst-to-sample ratio, and the least sensitive is reaction time.   Keywords: Catalytic Cracking, Ni Metal, OS, RSM, Silica

Combinatorial optimization of C4 olefin production conditions based on interpretable LSSVM&amp;TPE

Due to the complexity of the products from the ethanol coupling reaction, the C4 olefin yield tends to be low. Finding the optimal ethanol reaction conditions requires repeated manual experiments. In this paper, a novel learning framework based on least squares support vector machine and tree-structured parzen estimator is proposed to solve the optimization problem of C4 olefin production conditions. And shapley value is introduced to improve the interpretation ability of modeling method. The experimental results show that the proposed learning framework can obtain the combination of ethanol reaction conditions that maximized the C4 olefin yield It is nearly 17.30% higher compared to the current highest yield of 4472.81% obtained from manual experiments.

Manipulation of Electronic Effect and Assembly Architecture to Invoke Oxidation of Ethylbenzene by Hierarchical Co3O4 Wreaths.

A high-performance transition-metal oxide catalyst can be designed by appropriately integrating the concepts of morphology regulation and electronic structure modulation. In this work, hierarchical Co3O4 wreaths (CCW) enriched with oxygen vacancies (Ov) were facilely constructed for the selective oxidation of ethylbenzene (EB) to acetophenone (AP). Under the screened optimal reaction conditions, the CCW catalyst can offer a 79.1% conversion of EB (ri = 0.244 mol gcat-1 h-1) accompanied by a selectivity of 92.3% to AP. The good reaction performance can be attributed to the cooperation of defect engineering and architecture design, which can synergistically facilitate the EB oxidation performance by augmenting the intrinsic reactivity and accessibility of active sites. This work presents a reliable route to construct a high-performance transitional metal oxide catalyst via manipulation of electronic effect and assembly architecture for the selective oxidation of EB and beyond.