Search

Wind energy has gained tremendous attention recently due to its abundance potential and to obviate the adverse impacts of fossil fuel consumption. However, the efficient development and operation of wind energy systems require precise and accurate wind speed prediction. To fulfill this aim, machine learning algorithms have shown its prowess in accurately predicting the wind speed and this study proposes an interpretable stacked ensemble with ridge regressor utilizing ML algorithms such as catboost (CB), gradient boost (GB), multilayer perceptron (MLP), and random forest (RF) as a base model. The base models' estimations are integrated by applying a ridge regressor to enhance the accuracy of wind speed estimation. The dataset consists of 87 600 samples from which 80% samples are used for training. The proposed approach provides interpretability of the prediction results through Shapley additive explanations and feature importance analysis. The result of the proposed method is calculated by comparing the estimation outcomes with each model such as CB, GB, MLP, and RF in terms of error metrics such as root mean squared error (RMSE) and mean absolute error (MAE). The proposed model outperforms the others due to a reduction of error in RMSE by 19.89% and MAE by 24% respectively. [ABSTRACT FROM AUTHOR]

This work presents synthesis and characterization of two cobalt‐based coordination polymers (CPs) prepared by using two positionally related pyridine‐2,6‐dicarboxamide fragment‐based ligands containing appended arylcarboxylic acid groups. While arylcarboxylate groups of ligands coordinate to the Co(II) ions to produce 2D CPs; the amidic N−H groups remain free and generate large cavities lined with hydrogen bonds. Such hydrogen bonding cavities based CPs were found to reversibly adsorb molecular iodine. The Lewis acidic Co(II) ions and metal‐coordinated labile solvent molecules in CPs promoted noteworthy heterogeneous catalysis for Friedel crafts reactions as well as multicomponent condensation reactions. [ABSTRACT FROM AUTHOR]

Mutual induced-fit is well known process in biological system and playing crucial role in enzymatic catalysis, peptide-bond synthesis, protein synthesis, etc..., proceeds by mutual interactions of two or more than two components. However, in an artificial system, to mimic such process is challenging, especially by purely organic components. In this report, we have shown importance of mutual induced-fit in signal amplification of hydrogen-bonded capsule formation. Two different types of highly flexible ligands (one N-bridged and another triazine-bridged) are used. N-bridged tripodal ligand acting as clip over the adduct obtained from triazine-bridged ligand, bringing the resultant adduct in the cone-shape conformation. The resulting cone-shape conformation undergo solvent polarity dependent hydrogen-bonded capsule formation as a sole product. In absence of N-bridged tripodal ligand, only 50% capsule formation is observed through ¹H NMR at 100 mM concentration. However, in the presence of N-bridged tripodal ligand, organic components undergo mutual interactions to opt the cone-shape conformation and 100% capsule is formed (independent of concentration). The complete process is characterized by IR-spectra, ¹H and 13C NMR spectra, concentration dependent ¹H NMR titration spectra, ¹H-¹H COSY, ¹H-¹H NOESY, DOSY NMR, high resolution ESI mass spectra, and also by energy-minimized structure. [ABSTRACT FROM AUTHOR]

Summary: A decentralized application runs on the blockchain network without the intervention of a central authority. Transparency in transactions and security in vehicular networks are the issues for central systems. The proposed system uses blockchain‐based smart contracts, which eliminate the requirement for any third‐party verification. Additionally, with signature verification and reduced overhead, smart contracts also help in a fast and secure transaction. This study suggests a trust‐based system paradigm where certificate authority (CA) is employed for vehicle registration. We also propose a blockchain‐based system that provides efficient two‐way authentication and key agreement through encryption and digital signatures. The analysis of the proposed model reveals that it is an efficient way of establishing distributed trust management, which helps in preserving vehicle privacy. The proposed scheme is tested in Automated Validation of Internet Security‐sensitive Protocols (AVISPA), and security parameters verification in Network Simulator 2(NS2) also shows that the proposed scheme is more effective in comparison with existing schemes in terms of authentication cost, storage cost, and overhead. [ABSTRACT FROM AUTHOR]

OsMADS29 (M29) is a crucial regulator of seed development in rice. The expression of M29 is strictly regulated at transcriptional as well as post‐transcriptional levels. The MADS‐box proteins are known to bind to DNA as dimers. However, in the case of M29, the dimerization also plays a vital role in its localization into the nucleus. The factor(s) that affect oligomerization and nuclear transport of MADS proteins have not yet been characterized. By using BiFC in transgenic BY‐2 cell lines and Yeast‐2‐hybrid assay (Y2H), we show that calmodulin (CaM) interacts with M29 in a Ca2+‐dependent manner. This interaction specifically takes place in the cytoplasm, probably in association with the endoplasmic reticulum. By generating domain‐specific deletions, we show that both sites in M29 are involved in this interaction. Further, by using BiFC‐FRET‐FLIM, we demonstrate that CaM may also help in the dimerization of two M29 monomers. Since most MADS proteins have CaM binding domains, the interaction between these proteins could be a general regulatory mechanism for oligomerization and nuclear transport. [ABSTRACT FROM AUTHOR]

Summary: In heterogeneous access network, Multiple‐Input Multiple‐Output (MIMO) radio‐over‐fiber (RoF) system is an efficient approach for multiple signal transmission with low cost and complexity. The performance of RoF fronthaul system in MIMO system will be varied with different nonlinear effects. By adjusting various transmission parameters, such as the input signal power or the laser bias current, the nonlinear impacts produced by the RoF system can be reduced. In this paper, a novel algorithm Improved Aquila Optimization (IAO) is proposed to optimize transmission circumstances of MIMO RoF system. It determines the appropriate bias current for both lasers and Radio Frequency (RF) signal power in a short period. The input signals are wavelength multiplexed with Intensity Modulation and Direct Detection (IM/DD) applied. The carrier as well as transmission frequency is governed by the MIMO‐Long‐Term Evolution (LTE) standard. The proposed system is implemented in MATLAB, and the performance is evaluated. The experimental results show that fast convergence and trade‐off between noise and nonlinearity are obtained with varying bandwidth. In the experimental scenario, the maximum Error Vector Magnitude (EVM) of 1.88, 3.14, and signal‐to‐noise ratio (SNR) of 3.204, and 2.698 was attained for both quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) modulation. [Correction added on 24 April 2023, after first online publication: the SNR values were corrected in the preceding sentence.] For 100 iterations, the processing time was reduced to 0.137 s. When compared with the conventional state‐of‐the‐art approaches, the accuracy and computational complexity of the proposed approach are improved. [ABSTRACT FROM AUTHOR]

The present work describes the s‐trichlorotriazine (TCT)‐mediated formation of highly functionalized ester‐based drugs, namely nafamostat mesylate and camostat mesylate. The TCT‐mediated activation of acids followed by the attack of a hydroxyl group (−OH group) resulted in the formation of ester. The high aqueous solubility of cyanuric acid eases the work‐up process and avoids repetitive washing process (better E‐factor). The present method also avoids using pyridine as a base, and instead of that, N‐methylmorpholine (NMM) was used for the coupling. Moreover, we have also demonstrated the synthesis of key intermediates namely, 4‐guanidinobenzoic acid and 6‐hydroxy‐2‐naphthimidamide from economical and readily available raw materials. The TCT‐mediated coupling provides many advantages in scalability, cost‐effectiveness and environmental friendly handling. [ABSTRACT FROM AUTHOR]

In this paper, we studied the effect of increasing the conjugation in compound 3 on the proton transfer and aggregation‐induced emission properties. Compound 3 exhibited the dual absorption peak at 420 nm and 320 nm, which was redshifted by 50 nm compared to compound 2 (previous report). Compound 3 emits exhibited a peak at 530 nm with a Stokes' shift of 110 nm after photoexcitation at 420 nm. In a high polarity medium, the absorption and emission spectra of compound 3 showed redshifts of 50 nm and 20 nm, respectively. Further, compound 3 displayed the aggregation‐induced emission enhancement in THF/H2O (60 % v/v). Additionally, the proton transfer process in compounds 2 and 3 was evaluated through theoretical calculations via determining the relative free energies of possible tautomeric forms. It was determined that the small energy barriers for compound 2 in the S1 state suggested the presence of the proton transfer process; however, high energy barriers and high stabilization and Boltzmann population of 3.KK tautomeric form at S0 and S1 state for compound 3 discommoded the proton transfer process. Further, the aggregated form of compound 3 (20 μM; CH3OH/HEPES buffer (4 : 1; v/v) pH=7.04) was utilized to recognize Cu2+ ions with the lowest detection limit of 1.5 nM and Stern‐Volmer binding constant of 2.8×105 M−1. A noted decrease in the hydrodynamic size of compound 3 from 400 nm to 40 nm in the presence of Cu2+ ions confirmed the disaggregation with a decrease in emission intensity. Compound 3 was also employed as a Cu2+ ions recognizer in different collected samples with good percentage recovery. [ABSTRACT FROM AUTHOR]

Increasing world population, industrialization, and economic development demand more energy at a global scale, and this challenge is being met with the exploitation of fossil fuels that cause CO2 and CH4 emissions and contribute towards earth's rising temperature. Microalgae are considered potential sources for CO2 abatement and for combating food insecurity by ensuring a nutritional food supply for the sustainable living of an increasing population. The CO2 utilization potential of microalgae has been continuously researched for augmentation through various photobioreactor and open raceway pond designs and developments. Apart from recognition for their nutritional importance, microalgae are finding the place in the market as 'functional foods' due to their bioactive components. In view of this, the present study highlights the status and current attempts being made for photobioreactor development, CO2 sequestration, and the production of industrially important microalgal metabolites. This review also explains the factors responsible for microalgal growth and provides research needs and recommendations to make microalgal CO2 sequestration and value‐added compounds production an industrially competitive process. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

A (4+1)‐annulation of arylidene heterocyclic‐N‐fused imidazolones with α‐carbonyl sulfoxonium ylides has been developed. The reaction enabled efficient access to a range of N‐heterocycle‐fused furans, such as secondary hydroxyl and the structural parts of drug/bioactive compounds. A unique triple‐role of α‐carbonyl sulfoxonium ylides and a characteristic stereo‐electronic functional behavior of the arylidene N‐fused imidazolones have been explored. [ABSTRACT FROM AUTHOR]

A base controlled operationally simple catalytic system for the regioselective arylation of 2‐aryl‐imidazo[1,2‐a]pyridine by Pd catalyzed C−H activation has been developed. Herein, we report Pd/Ag2CO3 promoted C8 arylation of the heterocycles by overriding the N‐chelation on O‐chelation. In this way, various examples have been synthesized in good to excellent yield. Furthermore, Pd/t‐BuOK system has been developed for the novel deformylative C3 arylation of 2‐aryl‐imidazo[1,2‐a]pyridine. The choice of the catalytic system is also demonstrated for heteroarylation. Both standardized protocols have been explored with broad substrate scope and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Highlights Bio‐based flexible dielectric substrates have gained tremendous attention for their potential to reduce environmental risks from nonbiodegradable electronic waste. The present study demonstrates the fabrication of facile, nontoxic, and biodegradable chitosan‐based flexible dielectric substrate using graphene nanoplatelet (GNP) as a nanofiller. The detailed impact of different concentrations of GNP (1, 2, and 3 wt%) into the chitosan (CS) matrix was studied on physicochemical, morphological, mechanical, electrical, and thermal properties. The fabricated CS/GNP composites showed improved mechanical strength, thermal stability, and electrical properties compared with unmodified CS film. The composites exhibited excellent thermal stability (200°C) with a promising biodegradation rate (within 6 days). The mechanical strength of the unmodified CS film was increased unequivocally with 2 wt% GNP loading with tensile strength of 23.56 Mpa. Furthermore, the current–voltage (I–V) characteristic curves for CS/GNP (2%) and CS/GNP (3%) showed similar current conduction and ohmic behavior in flat, bending, and flat‐after‐bending modes. The dielectric measurements revealed that the CS/GNP composite with 2 wt% filler exhibited optimal performance having permittivity (έ) of 32.71 (at 102 Hz) with low dielectric loss of 0.04 (at 106 Hz). These results suggest that the dielectric films offer strong prospects as an eco‐friendly alternative for various applications. Biodegradable chitosan‐based flexible dielectric films were prepared. Films were made using a simple solvent casting method with 1–3 wt% GNP filler. Optimum physicochemical and electrical properties were seen at 2 wt% GNP. CS/GNP (2%) film exhibited ohmic behavior in both flat and bending modes. Excellent dielectric properties were achieved at 2 wt% GNP filler. [ABSTRACT FROM AUTHOR]