Danielskondrup3150

In China, coal-to-liquid (CTL) lube base oils with ultrahigh viscosity index (VI) are very popular. Since it consists of chain alkanes only and can be precisely characterized by molecular structures alone, quantitative 13C nuclear magnetic resonance (NMR) data are used to generate the average structural parameters (ASPs) of CTL base oil. In this work, the ASPs and bulk properties of CTL base oils were tested and compared with those of mineral base oils. Based on the test results, the correlation between the unique property of CTL base oil VI and ASPs was analyzed. To eliminate the effect of significant multicollinearity among the input variables, statistical methods such as ordinary least-squares (OLS), stepwise regression, and ridge regression methods were used to build the VI prediction model. The main findings are as follows according to the 13C NMR spectrum, CTL base oils had a significantly higher content of isomeric chain alkanes (including several branching structures) than mineral base oil, while the content of cycloalkanes was zero; among several branched structures, the one with the largest difference in content is structure S67, which has the highest percentage in the iso-paraffin structures, all above 25.5% in CTL base oils and below 21.39% in mineral oils; according to the distillation curve of the simulated distillation (SimDist) analysis, CTL base oils with similar carbon number distribution showed lower boiling points, narrower distillation ranges, and higher distillation efficiencies than mineral base oil; correlation analysis showed that the average chain length (ACL), normal paraffins (NPs), and structure S67 caused the CTL base oil to exhibit a higher VI; and from 13C NMR data, the ridge regression model was used to obtain regression coefficients consistent with reality, and the expected VI could be well predicted with a correlation coefficient of 0.935.In order to cut off the chain reaction in the process of coal oxidation at low temperature (COLT), butylated hydroxytoluene (BHT) was used as an inhibitor to explore its inhibition effect and mechanism. In this paper, in situ Fourier transform infrared spectroscopy, electron paramagnetic resonance, and gas production of COLT experiments were conducted to compare the inhibited coal sample (BHT-Coal) with the raw coal. The results showed that BHT can effectively inhibit the formation of active free radicals, reduce the content of active alkoxy, carbonyl, and hydroxyl groups, increase the production temperature of CO, CO2, and C2H4, and reduce the concentration. The crossing point temperature increased from 132.3 to 157.4 °C, indicating that BHT can reduce the spontaneous combustion tendency of the raw coal. To explore the inhibition mechanism of BHT on COLT, five typical active free-radical models were established, and their active sites, active bonds, and thermodynamic parameters were calculated according to the density functional theory. The results showed that the highly active H atoms of the phenolic hydroxyl group in BHT can combine with active free radicals to generate stable compounds, and the activation energy of each reaction is small, which can occur under normal temperature and pressure. The inhibition mechanism of BHT is to reduce the concentration of the free radicals, so as to weaken the chain reaction strength during the COLT. This study provides a reference for the development and utilization of inhibitors.A characteristic feature of cytochromes P450* is that the complex formed between the ferrous heme iron and carbon monoxide generates an intense absorption band at 450 nm. This unique feature of P450s is due to the proximal thiolate Cys ligand coordinated to the heme iron. Various harsh treatments shift this band to 420 nm, thereby giving P420 which is most often associated with an inactive form of the enzyme. Various explanations have been put forward to explain the P450-to-P420 change ranging from protonation of the Cys heme ligand, displacement of the Cys ligand, or replacement of the Cys ligand with His. There are two crystal structures of the well-studied cytochrome P450cam that have a high fraction of P420. In one, P450cam is cross-linked to its redox partner, putidaredoxin (Pdx), and the second is P450cam crystallized in the absence of substrate. In both of these structures, a significant part of the substrate pocket is disordered and the poor quality of the electron density for the substrate indicates substantial disorder. However, in both structures there is no detectable change in the Cys-iron ligation or surrounding structure. These results indicate that the P450-to-P420 switch is due primarily to an opening and disordering around the substrate binding pocket and not ligand displacement or ligand swapping. Since it remains a possibility that ligand swapping could be responsible for P420 in some cases, we mutated to Gln the 3 His residues (352, 355, and 361) close enough to the proximal side of the heme that could possibly serve as heme ligands. The triple variant forms P420 which indicates that swapping Cys for His is not a requirement for the P450-to-P420 switch.Protein-ligand binding affinity reflects the equilibrium thermodynamics of the protein-ligand binding process. Binding/unbinding kinetics is the other side of the coin. Computational models for interpreting the quantitative structure-kinetics relationship (QSKR) aim at predicting protein-ligand binding/unbinding kinetics based on protein structure, ligand structure, or their complex structure, which in principle can provide a more rational basis for structure-based drug design. Thus far, most of the public data sets used for deriving such QSKR models are rather limited in sample size and structural diversity. To tackle this problem, we have compiled a set of 680 protein-ligand complexes with experimental dissociation rate constants (k off), which were mainly curated from the references accumulated for updating our PDBbind database. Three-dimensional structure of each protein-ligand complex in this data set was either retrieved from the Protein Data Bank or carefully modeled based on a proper template. The entire data set covers 155 types of protein, with their dissociation kinetic constants (k off) spanning nearly 10 orders of magnitude. To the best of our knowledge, this data set is the largest of its kind reported publicly. Utilizing this data set, we derived a random forest (RF) model based on protein-ligand atom pair descriptors for predicting k off values. We also demonstrated that utilizing modeled structures as additional training samples will benefit the model performance. The RF model with mixed structures can serve as a baseline for testifying other more sophisticated QSKR models. selleck The whole data set, namely, PDBbind-koff-2020, is available for free download at our PDBbind-CN web site (http//www.pdbbind.org.cn/download.php).Catalytic pyrolysis of triglycerides to aromatics over zeolites is an advanced technology for a high value-added utilization of renewable biomass resources. Therefore, in this research, the catalytic performance of M/HZSM-5 catalysts (M = Zn, Ga, In, Ni, and Mo) during the pyrolysis process of glycerol trioleate and the effect of the compositional difference of several woody oils and waste oils on aromatic formation were investigated. Results revealed that Zn/HZSM-5 with appropriate acidity and metal sites reached the maximum aromatics yield (56.13%) and significantly enhanced the catalytic stability. In addition, these renewable nonedible oils were effectively converted to aromatics over the Zn/HZSM-5 catalyst, the aromatic yield of jatropha oil reached up to 50.33%, and the unsaturation and double bond number of feedstocks were crucial for the production of aromatics. The utilization of biomass resources to produce high value-added aromatics can alleviate the problems caused by the shortage of fossil resources and achieve sustainable green development.Heterologous production of limonene in microorganisms through the mevalonate (MVA) pathway has traditionally imposed metabolic burden and reduced cell fitness, where imbalanced stoichiometries among sequential enzymes result in the accumulation of toxic intermediates. Although prior studies have shown that changes to mRNA stability, RBS strength, and protein homology can be effective strategies for balancing enzyme levels in the MVA pathway, testing different variations of these parameters often requires distinct genetic constructs, which can exponentially increase assembly costs as pathways increase in size. Here, we developed a multi-input transcriptional circuit to regulate the MVA pathway, where four chemical inducers, l-arabinose (Ara), choline chloride (Cho), cuminic acid (Cuma), and isopropyl β-d-1-thiogalactopyranoside (IPTG), each regulate one of four orthogonal promoters. We tested modular transcriptional regulation of the MVA pathway by placing this circuit in an engineered Escherichia coli "marionette" strain, which enabled systematic and independent tuning of the first three enzymes (AtoB, HMGS, and HMGR) in the MVA pathway. By systematically testing combinations of chemical inducers as inputs, we investigated relationships between the expressions of different MVA pathway submodules, finding that limonene yields are sensitive to the coordinated transcriptional regulation of HMGS and HMGR.Resolution is an important index for evaluating the reconstruction performance of temperature distributions in a combustion environment, and a higher resolution is necessary to obtain more precise combustion diagnoses. Tunable diode laser absorption tomography (TDLAT) has proven to be a powerful combustion diagnosis method for efficient detection. However, restricted by the line-of-sight (LOS) measurement, the reconstruction resolution of TDLAT was dependent on the size of the detection data, which made it difficult to obtain sufficient data for extreme environmental measurements. This severely limits the development of TDLAT in combustion diagnosis. To overcome this limitation, we proposed a super-resolution reconstruction method based on the super-resolution residual U-Net (SRResUNet) to improve the reconstruction resolution using a software method that could take full advantage of residual networks and U-Net to extract the deep features from the limited data of TDLAT to reconstruct the temperature distribution efficiently. A simulation study was conducted to investigate how the parameters would affect the performance of the super-resolution model and to optimize the reconstruction. The results show that our SRResUNet model can effectively improve the accuracy of reconstruction with super-resolution, with good antinoise performance, with the errors of 2-, 4-, and 8-times super-resolution reconstructions of approximately 5.3, 7.4, and 9.7%, respectively. The successful demonstration of SRResUNet in this work indicates the possible applications of other deep learning methods, such as enhanced super-resolution generative adversarial networks (ESRGANs) for limited-data TDLAT.Posttranslational modifications (PTMs) are decisive factors in the structure, function, and localization of proteins in prokaryotic and eukaryotic organisms. However, prokaryotic organisms lack subcellular organelles, and protein localization based on subcellular locations like cytoplasm, inner membrane, periplasm, and outer membrane can be accounted for functional characterization. We have identified 131 acetylated, 1182 citrullinated, 72 glutarylated, 5 palmitoylated, and 139 phosphorylated proteins from Triton X-114 fractionated proteins of Leptospira, the pathogen of re-emerging zoonotic disease leptospirosis. In total, 74.7% of proteins were found exclusively in different Triton X-114 fractions. Additionally, 21.9% of proteins in multiple fractions had one or more PTM specific to different Triton X-114 fractions. Altogether, 96.6% of proteins showed exclusiveness to different Triton X-114 fractions either due to the presence of the entire protein or with a specific PTM type or position. Further, the PTM distribution within Triton X-114 fractions showed higher acetylation in aqueous, glutarylation in detergent, phosphorylation in pellet, and citrullination in wash fractions representing cytoplasmic, outer membrane, inner membrane, and extracellular locations, respectively.