The Application of Ionic Liquids in Dissolution and Separation of Lignocellulose

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Protein-Protein and Protein-DNA Interactions at The Bacteriophage T4 DNA Replication Fork. Characterization of a Fluorescently Labeled DNA Polymerase Sliding Clamp

The T4 DNA polymerase holoenzyme is composed of the polymerase enzyme complexed to the sliding clamp (the 45 protein), which is loaded onto DNA by an ATP-dependent clamp loader (the 44/62 complex). This paper describes a new method to directly investigate the mechanism of holoenzyme assembly using a fluorescently labeled cysteine mutant of the 45 protein. This protein possessed unaltered function yet produced substantial changes in probe fluorescence intensity upon interacting with other components of the holoenzyme. These fluorescence changes provide insight into the role of ATP hydrolysis in holoenzyme assembly. Using either ATP or the non-hydrolyzable ATP analog, adenosine 5′-O-(3-thiophosphate), events in holoenzyme assembly were assigned as either dependent or independent of ATP hydrolysis. A holoenzyme assembly mechanism is proposed in which the 44/62 complex mediates the association of the 45 protein with DNA in an ATP-dependent manner not requiring ATP hydrolysis. Upon ATP hydrolysis, the 44/62 complex triggers a conformational change in the 45 protein that may be attributed to the clamp loading onto DNA

Anti-electrostatic hydrogen bonding between anions of ionic liquids: A density functional theory study

Hydrogen bonds (HBs) play a crucial role in the physicochemical properties of ionic liquids (ILs). At present, HBs between cations and anions (Ca-An) or between cations (Ca-Ca) in ILs have been reported extensively. Here, we provided DFT evidences for the exists of HBs between anions (An-An) in the IL 1-(2-hydroxyethyl)-3-methylimidazolium 4-(2-hydroxyethyl)imidazolide [HEMIm][HEIm]. The thermodynamics stabilities of anionic, cationic, and H2O dimers together with ionic pairs were studied by potential energy scans. The results show that the cation-anion pair is the most stable one, while the HB in anionic dimer possesses similar thermodynamics stability to the water dimer. The further geometric, spectral and electronic structure analyses demonstrate that the inter-anionic HB meets the general theoretical criteria of traditional HBs. The strength order of four HBs in complexes is cation-anion pair > H2O dimer = cationic dimer > anionic dimer. The energy decomposition analysis indicates that induction and dispersion interactions are the crucial factors to overcome strong Coulomb repulsions, forming inter-anionic HBs. Lastly, the presence of inter-anionic HBs in ionic cluster has been confirmed by a global minimum search for a system containing two ionic pairs. Even though hydroxyl-functionalized cations are more likely to form HBs with anions, there still have inter-anionic HBs between hydroxyl groups in the low-lying structures. Our studies broaden the understanding of HBs in ionic liquids and support the recently proposed concept of anti-electrostatic HBs

Ionic Liquid Design and Process Simulation for Decarbonization of Shale Gas

Ionic liquids (ILs) have been receiving increasing attention as a potential decarbonization solvent. However, the enormous number of potential ILs that can be synthesized makes it a challenging task to search for the best IL for CO₂ removal from methane. In this work, a method was proposed to screen suitable ILs based on the COSMO-RS (conductor-like screening model for real solvents) model, an absorption mechanism, and experimental data. Besides the Henry’s constant, the viscosity and toxicity of ILs should also be taken into consideration for an industrial decarbonization process. Furthermore, process simulation was performed to evaluate the new IL-based decarbonization technology. Considering CO₂ solubility, CO₂/CH₄ selectivity and toxicity and viscosity of ILs, [bmim]­[NTf₂] has been screened to be the potential solvent among 90 classes of ILs. Based on reliable experimental data, a rigorous thermodynamic model was established. The simulation results have been found to agree well with the available experimental results. Two process flow sheet options, use of two single-stage flash operations or a multistage flash operation following the absorber, have been simulated and assessed. Compared with the well-known MDEA (methyldiethanolamine) process for CO₂ capture, the single-stage and multistage process alternatives would reduce the total energy consumption by 42.8% and 66.04%, respectively

Im/possible Lives: Gender, Class, Self-Fashioning, and Affinal Solidarity in Modern South Asia

Drawing on ethnographic research and employing a micro-historical approach that recognizes not only the transnational but also the culturally specific manifestations of modernity, this article centers on the efforts of a young woman to negotiate shifting and conflicting discourses about what a good life might consist of for a highly educated and high caste Hindu woman living at the margins of a nonetheless globalized world. Newly imaginable worlds in contemporary Mithila,South Asia, structure feeling and action in particularly gendered and classed ways, even as the capacity of individuals to actualize those worlds and the “modern” selves envisioned within them are constrained by both overt and subtle means. In the context of shifting cultural anchors, new practices of silence, literacy, and even behaviors interpreted as “mental illness” may become tactics in an individual’s negotiation of conflicting self-representations. The confluence of forces at play in contemporary Mithila, moreover, is creating new structures of feeling that may begin to reverse long-standing locally held assumptions about strong solidarities between natal families and daughters, on the one hand, and weak solidarities between affinal families and new daughters-in-law, on the other

Ionic Liquids as Bifunctional Cosolvents Enhanced CO₂ Conversion Catalysed by NADH-Dependent Formate Dehydrogenase

Efficient CO2 conversion by formate dehydrogenase is limited by the low CO2 concentrations that can be reached in traditional buffers. The use of ionic liquids was proposed as a manner to increase CO2 concentration in the reaction system. It has been found, however, that the required cofactor (NADH) heavily degraded during the enzymatic reaction and that acidity was the main reason. Acidity, indeed, resulted in reduction of the conversion of CO2 into formic acid and contributed to overestimate the amount of formic acid produced when the progression of the reaction was followed by a decrease in NADH absorbance (method N). Stability of NADH and the mechanism of NADH degradation was investigated by UV, NMR and by DFT calculations. It was found that by selecting neutral-basic ionic liquids and by adjusting the concentration of the ionic liquid in the buffer, the concentration of NADH can be maintained in the reaction system with little loss. Conversion of CO2 to methanol in BmimBF(4) (67.1%) was more than twice as compared with the conversion attained by the enzymatic reaction in phosphate buffer (24.3%)

In-situ synthesis of interconnected SWCNT/OMC framework on silicon nanoparticles for high performance lithium-ion batteries

AbstractIn spite of silicon has a superior theoretical capacity, the large volume expansion of Si anodes during Li+ insertion/extraction is the bottle neck that results in fast capacity fading and poor cycling performance. In this paper, we report a silicon, single-walled carbon nanotube, and ordered mesoporous carbon nanocomposite synthesized by an evaporation-induced self-assembly process, in which silicon nanoparticles and single-walled carbon nanotubes were added into the phenolic resol with F-127 for co-condensation. The ordered mesoporous carbon matrix and single-walled carbon nanotubes network could effectively accommodate the volume change of silicon nanoparticles, and the ordered mesoporous structure could also provide efficient channels for the fast transport of Li-ions. As a consequence, this hybrid material exhibits a reversible capacity of 861 mAh g−1 after 150 cycles at a current density of 400 mA g−1. It achieves significant improvement in the electrochemical performance when compared with the raw materials and Si nanoparticle anodes