Ionic liquids (ILs) have gained increasing attention as solvents in chemical and biotechnological applications. Since alcohol dehydrogenases are of prime interest in industrial field, the present ...study has been conducted to study the influence of imidazolium based ionic liquids on kinetics, structure and stability of the thermophilic Thermoanaerobacter brockii (TBADH) alcohol dehydrogenase. Our results exhibited that the ionic liquids could affect kinetic parameters and stability, but not the tertiary structure. Through the determination of inhibition profile, which revealed mixed inhibition, Ki (affinity of IL for the enzyme) and KI (affinity of IL for enzyme–substrate complex) values were calculated. Structural analysis using crystallographic data from protein data bank elucidated the structural details responsible for different responses of alcohol dehydrogenases toward ionic liquids. Finally, enhanced stability in MImCl was discussed.
► Oxidoreductases have not been studied in ionic liquid media extensively. ► Thermophilic alcohol dehydrogenase is a NADP+ dependent oxidoreductase. ► Imidazolium based ionic liquids are similar in structure to NADP+. ► They stabilize alcohol dehydrogenase via active site preservation. ► Structural analysis revealed the reason for severe effect of ionic liquids on thermostable alcohol dehydrogenase.
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•Fe3O4@SiO2-Si(CH2)3N-acyclovir-Cu(I) as a recoverable and green catalyst was designed and synthesized.•Performing for C–N cross‐coupling reaction in cheap, sustainable, low toxicity ...and green solvent.•Used potassium carbonate and ethylene glycol (EG) as a deep eutectic solvent in reaction.•Catalytic activity and stability of nanoparticles were investigated by experimental and theoretical method.
A copper(I)‐acyclovir complex supported on magnetic was designed and successfully synthesized. Catalytic activity and stability of two structures of copper(I)‐acyclovir complex supported on magnetic were investigated by the theoretical method. The more active and stable copper(I)‐acyclovir complex supported on magnetic was applied as a catalyst for C–N cross‐coupling reaction with high yield in a deep eutectic solvent (DES) as a green solvent. Also, these nanoparticles could be easily recovered and reused for new rounds of reaction without any considerable loss in catalytic activity.
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•The detailed investigation of mechanism for organocatalytic generation of p-QDM.•The effect of substituents on the ε-functionalization were examined.•The optical properties of ...different p-QDM derivatives were discovered.•The role of NHC-catalyst and in-situ generated HCO3– base were assessed.•Rational tuning of chemical reactivity and optical properties of p-QDM compounds.
Recently, Ye and his co-worker reported a fascinating work that proposed a procedure for generation of p-quinodimethane (p-DQM) via N-heterocyclic carbene (NHC) catalysis for use in the organic synthesis. The remarkable point of this method is related to its capability for ε-functionalization. In this work, the detailed mechanism of NHC-catalyzed production of p-DQM and its ε-functionalization with different trifluoromethyl ketone (TFMK) derivatives were investigated using density functional theory (DFT). Indeed, the role of different substituents on the NHC part of p-QDM on the chemical reactivity and optical properties of this compound was examined. The optical properties and charge transfer indexes were evaluated using TD-DFT method. The results indicated that the chemical reactivity and optical properties of p-QDM compounds can be rationally controlled by the variation of different substituents on the NHC part of them. This computational study paves the way for rational applications of NHC-catalyzed p-QDM in organic synthesis.
Amides can be synthesized directly from aldehydes and amines in high yield using a catalyst. The reaction, involving aldehydes and amines, was carried out in a mixture containing choline chloride and ...aluminum nitrate as a solvent and a catalyst to produce amides. Such catalyst was far more effective compared to other current catalytic systems. The reaction consistently gave exceptionally remarkable results for various aldehyde and amine derivatives under the specified reaction conditions. This method offers several advantages, including easy separation of products, efficiency, environmentally safe nature of the solvent, and elimination of expensive and hazardous catalysts. These features emphasize the importance of such groundbreaking reactions. Due to the significant polar characteristics and insolubility of the resulting products in water, the addition of water into the reaction mixture facilitates the easy separation of the products from the reaction medium. Consequently, this particular ionic liquid method provides a simple route for the synthesis of these important compounds.
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A novel magnetic core–shell Fe2O3@proline–CuMgAl–L(ayered)D(ouble)H(ydroxide) was designed as an efficient bifunctional catalytic system. To this end, Cu (II) was combined with Mg and Al in the LDH ...structure and l‐proline was intercalated between LDH layers in order to perform a straightforward synthesis of quinolines and 2H‐indazoles as two important pharmaceutical N‐aryl‐substituted heterocyclic compounds. In this regard, a facile method was employed through consecutive condensation under a mild conditions in choline azide media, which played the role of a reagent and a solvent to avoid toxic solvents and hazardous azidation reagents. These techniques provided considerable improvement in terms of using green media, reducing starting materials, reaching higher yields and offering a shorter reaction time and lower temperature. In conclusion, it was found that the catalyst could be reused five times with no significant loss of activity.
A biocompatible Fe2O3@proline–Cu–LDH catalytic system including transition metal and organocatalyst was designed for the facile and one‐pot synthesis of quinolines and 2H‐indazoles as two important pharmaceutical N‐aryl substituted heterocyclic compounds. A simple procedure under choline azide media as deep eutectic solvent and reagent is presented.
The effects of three periods of exposure (12, 24 and 48 h) to different levels of putrescine (0, 0.2, 0.5, 1.0, 2.0 and 5.0 mg l⁻¹), as well as three incubation periods (24, 48 and 72 h) to different ...levels of cefotaxime and vancomycin (0, 50, 100, 200 and 500 mg l⁻¹) on microspore embryogenesis of rapeseed cv. ‘Hyola 401’ were assessed. Microspore embryogenesis was enhanced about threefold compared with untreated culture following 48 h treatment with 0.2 mg l⁻¹ putrescine. Putrescine treatment at 0.5 mg l⁻¹ for 48 h effectively induced root formation and increased normal plantlet regeneration by 92 % when microspore-derived embryos (MDEs) were transferred to regeneration medium. The highest embryo yield (184.2 embryos Petri dish⁻¹) was possible when induction medium was supplemented with 50 mg l⁻¹ cefotaxime for 24 h and the highest normal regeneration was observed in cultures exposed to 50 and 100 mg l⁻¹ at all durations tested. More abnormal MDEs (76 and 82 %) were observed when microspores treated with 200 and 500 mg l⁻¹ cefotaxime many of which failed to regenerate normally and resulted in callusing. Vancomycin at 100 mg l⁻¹ during the 48 h exposure increased the number of MDEs (181.6 embryos Petri dish⁻¹) in contrast to untreated cultures (93.6 embryos Petri dish⁻¹) but, normal plantlet regeneration decreased as vancomycin level increased and high callusing (84 and 90 %) was observed with 200 and 500 mg l⁻¹ for 72 h. Microspore embryogenesis and plant regeneration could be improved by putrescine, cefotaxime and vancomycin when appropriate levels and durations of incubation were selected.
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•Magnetic modified cellulose decorated with palladium nanoparticles was well synthesized.•A quantitative description of metal-ligand interactions was prepared.•High catalytic activity ...was obtained for Suzuki and Sonogashira reactions in deep eutectic solvent.•The nanocatalyst exhibited favorable stability and reusability.
A highly efficient metal-based nanocatalyst was developed by stabilization of palladium nanoparticles on magnetically retrievable phosphine-functionalized cellulose (Fe3O4@PFC-Pd(0)). The synthesized nanocatalyst was characterized by various techniques such as FT-IR, XRD, FE-SEM, TEM, EDX, UV–vis, ICP, TGA, BET and VSM. Moreover, to investigate the metal-ligand interactions present in the nanocatalyst, covalent and electrostatic interactions, density functional theory (DFT) and quantum theory of atoms in molecule (QTAIM) methods were employed. The catalytic efficacy of the nanoparticles was evaluated in Sonogashira and Suzuki coupling reactions in basic deep eutectic mixture, as a sustainable solvent. Due to the cooperative interactions of primary hydroxyl group of cellulose, phosphorus atom and phenyl ring of phosphine moiety with Pd atom, the nanocatalyst exhibits high activity and stability. The nanocatalyst can be easily recycled and reused at least five times without an appreciable loss of activity. Also, the other merits including short reaction times, short synthetic route to prepare catalyst, trace metal leaching to the reaction medium, cost-effective and eco-friendly conditions can be mentioned for the present approach.
This study came as an attempt to predict the foreign direct investment of the State of Qatar, depending on the model of artificial neural networks and the comparison between its models, because this ...type of model takes into account the non-linear and stochastic characteristics that characterize the financial and economic chains in general. A multi-layer artificial neural network was built consisting of three layers (the input layer, the hidden layer, the output layer), and the number of training passes was installed 999 times, and the network learning rate was 0.6 and the activation function used is the SIGMOID function using the back propagation algorithm. The MLP (4-10-1) model gave accurate results that are close to the actual values, and it also gave the lowest values for the error measurement criteria represented in the MAE, RMSE and MAPE standards. This reflects the strength of the predicted model, which is consistent with the results of most studies that have been conducted on the subject, both Arab and foreign. It turned out that the feed-forward artificial neural network model is superior to other network models, as the outputs of the hidden layer are inputs for the time following the next time, which can be relied upon as an appropriate method for future prediction of the GDP of the State of Qatar. Also, the forecast values are positive for the period (2020-2040), which encourages increased investor attraction and market recovery in subsequent periods.
Statistical process control (SPC) is a significant method to monitor processes and ensure quality. Control charts are the most important tools in SPC. As production processes and production parts ...become more complex, there is a need to design control charts using more complex distributions. One of the most important control charts to monitor the number of nonconformities in production processes is the C-chart, which uses the Poisson distribution as a quality characteristic distribution. However, to fit the Poisson distribution to the count data, equality of mean and variance should be satisfied. In some cases, such as biological and medical sciences, count data exhibit overdispersion, which means that the variance of data is greater than the mean. In such cases, we can use the Poisson–Lindley distribution instead of the Poisson distribution to model the count data. In this paper, we first discuss some important characteristics of the Poisson–Lindley distribution. Then, we present parametric and bootstrap control charts when the observations follow the Poisson–Lindley distribution and analyze their performance. Finally, we provide a simulated example and a real-world dataset to demonstrate the implementation of control charts. The results show the good performance of the proposed control charts.
The survey of reports regarding high concentrations of arsenic in soils and groundwater around the world, which refers to increase of arsenic exposure to the living organisms, has been increased. In ...this research work arsenic immobilization process using three iron amendments (soluble Fe(II), zero-valent iron (ZVI), and Fe (II)-modified zeolite (Fe-Z)) was modeled and optimized in a spiked soil by response surface methodology (RSM). Three factors including initial concentration of As(III) (20 to 580mgkg−1 of soil), amount of added Fe (0.5 to 2.5wt.% of soil for both Fe(II) and ZVI, 0.05 to 0.2wt.% of soil for loaded Fe on zeolite) and shaking time (15 to 960min) were selected as the independent factors on arsenic immobilization efficiency. The five-level central composite design (CCD) was used for experiment design and optimization model parameters. Variance analysis showed that CCD models were statistically significant for all amendments (p<0.01) with high accuracy (R2=0.98 for Fe(II), R2=0.89 for ZVI and R2=0.92 for Fe-Z) in predicting As(III) immobilization. Optimization results showed that at 200mgAskg−1 soil and 600minute shaking time, the immobilization of As(III) with Fe(II), ZVI and Fe-Z was 90.6%, 92% and 81.4%, respectively. However ZVI was most effective amendment, but with negligible difference in immobilization As(III), Fe(II) is more economical. In conclusion Fe(II) was more efficient and cost-effective than ZVI and Fe-Z in long-term immobilization.
![Fe2O3@[proline]–CuMgAl–LDH:...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0268-2605/small "Fe2O3@[proline]–CuMgAl–LDH: A magnetic bifunctional copper and organocatalyst system for one‐pot synthesis of quinolines and 2H‐indazoles in green media")
