Binding Thermodynamics and Dissociation Kinetics Analysis Uncover the Key Structural Motifs of Phenoxyphenol Derivatives as the Direct InhA Inhibitors and the Hotspot Residues of InhA

Given the current epidemic of multidrug-resistant tuberculosis, there is an urgent need to develop new drugs to combat drug-resistant tuberculosis. Direct inhibitors of the InhA target do not require activation and thus can overcome drug resistance caused by mutations in drug-activating enzymes. In this work, the binding thermodynamic and kinetic information of InhA to its direct inhibitors, phenoxyphenol derivatives, were explored through multiple computer-aided drug design (CADD) strategies. The results show that the van der Waals interactions were the main driving force for protein–ligand binding, among which hydrophobic residues such as Tyr158, Phe149, Met199 and Ile202 have high energy contribution. The AHRR pharmacophore model generated by multiple ligands demonstrated that phenoxyphenol derivatives inhibitors can form pi–pi stacking and hydrophobic interactions with InhA target. In addition, the order of residence time predicted by random acceleration molecular dynamics was consistent with the experimental values. The intermediate states of these inhibitors could form hydrogen bonds and van der Waals interactions with surrounding residues during dissociation. Overall, the binding and dissociation mechanisms at the atomic level obtained in this work can provide important theoretical guidance for the development of InhA direct inhibitors with higher activity and proper residence time

Metainformation And Workflow Management For Solving Complex Problems In Grid Environments

In this paper we discuss the semantics of process and case description necessary for the workflow management on a grid used for scientific applications and outline the structure of basic ontologies supporting the coordinated execution of complex tasks. We survey the core services provided by our environment and discuss in some detail the planning service

The Preparation of a Lignosulfonate/Chitosan–Graphene Oxide Hydrogel Biosorbent to Effectively Remove Cr(VI) from Wastewater: Adsorption Performance and Mechanisms

A lignosulfonate/chitosan–graphene oxide hydrogel (LCGH) composite was successfully synthesized to effectively remove Cr(VI) from wastewater. The physical–chemical properties of the prepared LCGH was characterized by SEM, FT-IR, XRD, XPS, and TGA. The results showed that LCGH had an cross-linked three-dimensional porous network structure that was conducive to Cr(VI) adsorption, resulting in a high Cr(VI) adsorption capacity (564.2 mg/g). Thermodynamic analysis showed that Cr(VI) adsorption on LCGH was spontaneous endothermic and fitted well with the pseudo-second-order kinetic and Langmuir models. The reaction mechanisms for Cr(VI) removal were hydrogen bond, electrostatic attraction, and π-π interaction. LCGH demonstrated good reproducibility and its adsorption capacity of Cr(VI) could still maintained at 85.4% after 5 cycles of regeneration. The biosorbent LCGH was a low-cost and eco-friendly material, which has a good prospect for Cr(VI) wastewater removal

Fabrication of Polyethyleneimine-Modified Nanocellulose/Magnetic Bentonite Composite as a Functional Biosorbent for Efficient Removal of Cu(Ⅱ)

A novel inorganic–organic biosorbent, polyethyleneimine (PEI)-modified nanocellulose cross-linked with magnetic bentonite, was prepared for the removal of Cu(Ⅱ) from water. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) showed that the amino and carboxyl groups were successfully grafted onto the nanocellulose structure. The adsorption performance of Cu(Ⅱ) with various factors, using the biosorbent, was investigated. The results show that the adsorption equilibrium could be reached within a short time (10 min), and the adsorption capacity of Cu(Ⅱ) reached up to 757.45 mg/g. The adsorption kinetics and adsorption isotherms were well-fitted with the pseudo-second-order and the Freundlich isotherm models, respectively. The adsorption process of the composite is mainly controlled by chemisorption, and functional group chelation and electrostatic force were the adsorption mechanisms; pore filling also has a great influence on the adsorption of Cu(Ⅱ). It was found that the prepared modified nanocellulose composite has great potential for the removal of heavy metals from water

The Preparation of a Lignosulfonate/Chitosan–Graphene Oxide Hydrogel Biosorbent to Effectively Remove Cr(VI) from Wastewater: Adsorption Performance and Mechanisms

A lignosulfonate/chitosan–graphene oxide hydrogel (LCGH) composite was successfully synthesized to effectively remove Cr(VI) from wastewater. The physical–chemical properties of the prepared LCGH was characterized by SEM, FT-IR, XRD, XPS, and TGA. The results showed that LCGH had an cross-linked three-dimensional porous network structure that was conducive to Cr(VI) adsorption, resulting in a high Cr(VI) adsorption capacity (564.2 mg/g). Thermodynamic analysis showed that Cr(VI) adsorption on LCGH was spontaneous endothermic and fitted well with the pseudo-second-order kinetic and Langmuir models. The reaction mechanisms for Cr(VI) removal were hydrogen bond, electrostatic attraction, and π-π interaction. LCGH demonstrated good reproducibility and its adsorption capacity of Cr(VI) could still maintained at 85.4% after 5 cycles of regeneration. The biosorbent LCGH was a low-cost and eco-friendly material, which has a good prospect for Cr(VI) wastewater removal

Research Progress on Adsorption of Arsenic from Water by Modified Biochar and Its Mechanism: A Review

Arsenic (As) is a non-metallic element, which is widely distributed in nature. Due to its toxicity, arsenic is seriously harmful to human health and the environment. Therefore, it is particularly important to effectively remove arsenic from water. Biochar is a carbon-rich adsorption material with advantages such as large specific surface area, high porosity, and abundant functional groups, but the original biochar has limitations in application, such as limited adsorption capacity and adsorption range. The modified biochar materials have largely enhanced the adsorption capacity of As in water due to their improved physicochemical properties. In this review, the changes in the physicochemical properties of biochar before and after modification were compared by SEM, XRD, XPS, FT-IR, TG, and other characterization techniques. Through the analysis, it was found that the adsorbent dosage and pH are the major factors that influence the As adsorption capacity of the modified biochar. The adsorption process of As by biochar is endothermic, and increasing the reaction temperature is conducive to the progress of adsorption. Results showed that the main mechanisms include complexation, electrostatic interaction, and precipitation for the As removal by the modified biochar. Research in the field of biochar is progressing rapidly, with numerous achievements and new types of biochar-based materials prepared with super-strong adsorption capacity for As. There is still much space for in-depth research in this field. Therefore, the future research interests and applications are put forward in this review

Are Roaming and Conventional Saddle Points for H₂CO and CH₃CHO Dissociation to Molecular Products Isolated from Each Other?

High-level ab initio calculations are performed to examine previously unexplored regions of full-dimensional potential energy surfaces that connect the conventional and recently reported “roaming” saddle points for the H₂CO and CH₃CHO unimolecular dissociations to form molecular products, H₂ + CO and CH₄ + CO, respectively. The aim of this investigation is to determine whether or not there are large barriers separating these saddle points and their associated intrinsic reaction pathways. The results are of fundamental significance in formulating statistical and reduced dimensionality dynamical approaches to model these reactions, including both pathways

Redox Couple Modulation in NASICON Phosphates toward High-Performance Cathodes for Na-Ion Batteries

Natrium superionic conductor (NASICON)-type phosphates have aroused a great interest as cathode materials for sodium-ion batteries (SIBs) by virtue of their stable 3-dimensional frameworks, flexible molecular formula tunability, and superior ionic conductivity. Nevertheless, the intrinsic low electronic conductivity and relatively low theoretical specific capacity place obstacles in their way toward achieving higher electrochemical performance. In addition, only 2-electron reactions in most NASICON cathodes and poor reversibility of high-voltage redox couples severely limit their energy density. To address the above tough issues, an in-depth understanding of transition metal selection, elements ratio optimization, and Na-storage mechanism is of paramount importance. Here, this mini review summarizes the latest progresses on the NASICON-type phosphate cathodes for SIBs from the perspective of redox couple modulation. NASICON cathodes featuring high operating voltage and multielectron reactions are discussed in detail. Finally, the remaining challenges and personal outlooks based on redox couple regulation are put forward, shedding light on the designing rules for high-energy and long-durability NASICON-type phosphate cathodes for SIBs in the future