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The aim of this study was to investigate an effective approach for improving the dissolving pulp properties for making specialty fiber. The caustic and enzymatic treatment of the properties of dissolving pulp was conducted by analyzing the macromolecular structure and chemical composition. The results showed that the enzymatic treatment was more effective on influencing the macromolecular properties, while the caustic treatment had more influence on structural changing, mainly cellulose crystal structure and crystallinity. Meanwhile, to maintain a higher purity and higher brightness, caustic treatment would be beneficial in comparison with enzymatic treatment. The performance of caustic treated sample was evaluated in regarding to chemical composition and acetylation reaction performance, using commercial pulp as reference. The competitive feature of treated sample suggested its potential in future application. [ABSTRACT FROM AUTHOR]

We predicted water-octanol partition coefficients for the molecules in the SAMPL7 challenge with explicit solvent classical molecular dynamics (MD) simulations. Water hydration free energies and octanol solvation free energies were calculated with a windowed alchemical free energy approach. Three commonly used force fields (AMBER GAFF, CHARMM CGenFF, OPLS-AA) were tested. Special emphasis was placed on converging all simulations, using a criterion developed for the SAMPL6 challenge. In aggregate, over 1000 μ s of simulations were performed, with some free energy windows remaining not fully converged even after 1 μ s of simulation time. Nevertheless, the amount of sampling produced log P ow estimates with a precision of 0.1 log units or better for converged simulations. Despite being probably as fully sampled as can expected and is feasible, the agreement with experiment remained modest for all force fields, with no force field performing better than 1.6 in root mean squared error. Overall, our results indicate that a large amount of sampling is necessary to produce precise log P ow predictions for the SAMPL7 compounds and that high precision does not necessarily lead to high accuracy. Thus, fundamental problems remain to be solved for physics-based log P ow predictions. [ABSTRACT FROM AUTHOR]

All-atom molecular dynamics simulations with stratified alchemical free energy calculations were used to predict the octanol-water partition coefficient log P ow of eleven small molecules as part of the SAMPL6- log P blind prediction challenge using four different force field parametrizations: standard OPLS-AA with transferable charges, OPLS-AA with non-transferable CM1A charges, AMBER/GAFF, and CHARMM/CGenFF. Octanol parameters for OPLS-AA, GAFF and CHARMM were validated by comparing the density as a function of temperature, the chemical potential, and the hydration free energy to experimental values. The partition coefficients were calculated from the solvation free energy for the compounds in water and pure ("dry") octanol or "wet" octanol with 27 mol% water dissolved. Absolute solvation free energies were computed by thermodynamic integration (TI) and the multistate Bennett acceptance ratio with uncorrelated samples from data generated by an established protocol using 5-ns windowed alchemical free energy perturbation (FEP) calculations with the Gromacs molecular dynamics package. Equilibration of sets of FEP simulations was quantified by a new measure of convergence based on the analysis of forward and time-reversed trajectories. The accuracy of the log P ow predictions was assessed by descriptive statistical measures such as the root mean square error (RMSE) of the data set compared to the experimental values. Discarding the first 1 ns of each 5-ns window as an equilibration phase had a large effect on the GAFF data, where it improved the RMSE by up to 0.8 log units, while the effect for other data sets was smaller or marginally worsened the agreement. Overall, CGenFF gave the best prediction with RMSE 1.2 log units, although for only eight molecules because the current CGenFF workflow for Gromacs does not generate files for certain halogen-containing compounds. Over all eleven compounds, GAFF gave an RMSE of 1.5. The effect of using a mixed water/octanol solvent slightly decreased the accuracy for CGenFF and GAFF and slightly increased it for OPLS-AA. The GAFF and OPLS-AA results displayed a systematic error where molecules were too hydrophobic whereas CGenFF appeared to be more balanced, at least on this small data set. [ABSTRACT FROM AUTHOR]

This work introduces the interactive method of partitioned finite element and interface element (PFE/IE) to analyse the dynamic behaviours of structures with discontinuous deformations. The dynamic IE equations can be derived by combining the nonlinear equation based on the Newmark method and the dynamic equilibrium equation. The nodal displacement can be solved via PFE by combining the contact force into the total force vector; consequently, the failure state can be procured. PFE/IE improves the computational efficiency as nonlinear iteration is limited to the possible contact region. Dynamic results obtained with other techniques or experiments are introduced and compared to validate the accuracy and robustness of PFE/IE. [ABSTRACT FROM AUTHOR]

Despite tremendous success of molecular targeted therapy together with immunotherapy, only a small subset of patients can benefit from them. Chemotherapy remains the mainstay treatment for most of tumors including non-small cell lung cancer (NSCLC); however, non-selective adverse effects on healthy tissues and secondary resistance are the main obstacles. Meanwhile, the quiescent or dormant cancer stem-like cells (CSLCs) are resistant to antimitotic chemoradiotherapy. Complete remission can only be realized when both proliferative cancer cells and quiescent cancer stem cells are targeted. In the present research, we constructed a cooperatively combating conjugate (DTX-P7) composed of docetaxel (DTX) and a heptapeptide (P7), which specifically binds to cell surface Hsp90, and assessed the anti-tumor effects of DTX-P7 on non-small cell lung cancer. DTX-P7 preferentially suppressed tumor growth compared with DTX in vivo with a favorable distribution to tumor tissues and long circulation half-life. Furthermore, we revealed a distinctive mechanism whereby DTX-P7 induced unfolded protein response and eventually promoted apoptosis. More importantly, we found that DTX-P7 promoted cell cycle reentry of slow-proliferating CSLCs and subsequently killed them, exhibiting a "proliferate to kill" pattern. Collecitvely, by force of active targeting delivery of DTX via membrane-bound Hsp90, DTX-P7 induces unfolded protein response and subsequent apoptosis by degrading Hsp90, meanwhile awakens and kills the dormant cancer stem cells. Thus, DTX-P7 deserves further development as a promising anticancer therapeutic for treatment of various membrane-harboring Hsp90 cancer types. [ABSTRACT FROM AUTHOR]

This paper presents analysis of water jet flow state in an ecological tunnel in an abnormal condition and failure analysis of a temporary blocking gate of the ecological tunnel. Analysis consists of the determination of the hydrodynamic pressure on the gate by using experimental test and computational fluid dynamics, the calculation of stress distribution under different operating conditions using finite element method, and a simplified fatigue analysis. Results show that the water jet flow induces a vortex downstream the blocking gate, and under the large displacement and large dynamic stress the damage of gate begins with the local material failure and spreads to total damage with sandwich panel. [ABSTRACT FROM AUTHOR]

The dynamic stability evaluation of jointed rock slopes is a complex problem of solving nonlinear and uncertain systems. The interactive method of partitioned finite element and interface element is applied to the solution of the seismic response of jointed rock slopes under earthquake. The contact status of the weak interlayer can be calculated at each moment by the method. Since the balance of the slope slider can be inferred by contact status on weak interlayer, a novel criterion of rock slope instability based on the contact status of the contact surface is proposed. The criterion not only satisfies the requirement for the sudden change of residual deformation but also meets the completely broken of the weak interlayer. Since the interactive method can still converge in the state of slope failed, an adaptive strength reduction method is proposed to search for the safety factor automatically. To verify the effectiveness of the method, the dynamic stability of a classical rock jointed slope is calculated, and then compared with the result in the reference paper. Moreover, the proposed method is applied to analyze the dynamic stability of a high steep rock slope with complex internal joints and the safety factor is calculated successfully. [ABSTRACT FROM AUTHOR]

• A variable parameters constitutive model of concrete is proposed. • This model reflects progressive failure progress of concrete. • This model can more conducive to analysis multi-axial stress state. • This model can reflect the stress drop in the descending section better. A novel four-parameters damage constitutive model for concrete in strain space is proposed in this paper. It is based on the Heish-Ting-Chen constitutive model and is derived in the framework of the thermodynamics of irreversible process. Because tension damage is a major fracture mode in concrete used for hydraulic structures, an equivalent strain is introduced that converts the multi-axial strain state into the equivalent tension strain to determine the tension damage. Considering the change in the equations' parameters during progressive failure, a variable parameters constitutive model is established. The parameters of the damage constitutive model are obtained by the increasing section and the decreasing section of stress-strain curve and it is demonstrated that the proposed model performs better than the regular constitutive model in the decreasing section. The numerical implementations provide a good description of the failure process as well as an accurate prediction of the behaviour of concrete. [ABSTRACT FROM AUTHOR]