Optimization Design of Step Stress Accelerated Degradation Test for Motorized Spindle Based on Ds-Optimality

In the accelerated degradation test (ADT) of motorized spindles, it is necessary to apply a variety of stresses to simulate real working conditions. However, the traditional accelerated test scheme optimization method does not consider the weight of various stresses in the test, resulting in the evaluation accuracy of important stress parameters in the model being too low. In order to solve this problem, an optimal design method of the step stress accelerated degradation test (SSADT) scheme for motorized spindles is proposed based on Ds-optimality. Firstly, the fault tree analysis (FTA) method is used to analyze the collected fault data of motorized spindles and screen the main stress. Then, the accelerated degradation model is established by using drift Brownian motion. Based on the Ds-optimality, the optimization variables and constraints in the test are determined, and the optimization model is established with the objective of minimizing the estimated variance of the main stress parameters in the acceleration model; additionally, the optimization steps are given. Finally, an example is given to verify the effectiveness of the method. Sensitivity analysis of the optimization results shows that the method has good robustness

Highly Efficient and Reusable Montmorillonite/Fe3O4/Humic Acid Nanocomposites for Simultaneous Removal of Cr(VI) and Aniline

Recyclable nanomaterials are in great need to develop clean technology for applications in the removal of water contaminants. In this work, easily separable montmorillonite/Fe3O4/humic acid (MFH) nanocomposites were fabricated through a facile hydrothermal route. It was found the adsorption ability and stability of MFH was significantly enhanced due to the synergistic effects between montmorillonite, Fe3O4 nanoparticles and humic acid. The MFH nanocomposites are highly efficient and recyclable as they can remove at least 82.3% of Cr(VI) and 95.1% of aniline in six consecutive runs. The adsorption mechanism was investigated by analyzing the kinetic parameters of pseudo first-order, pseudo second-order, and intraparticle diffusion models and describing the equilibrium isotherms of Langmuir and Freundlich models. Results indicated different adsorption mechanisms of Cr(VI) and aniline by MFH. The readily synthesized MFH nanocomposites can act as effective and practical materials for environmental applications

Biological Characteristics, Genome-wide Characteristics of A Bacteriophage of Vibrio parahaemolyticus and Its Application in Food

Objective: The purpose of this study was to investigate the biological characteristics, whole genome, and antibacterial effect of V. parahaemolyticus phage 474x1 in food. Methods: The phage 474x1 was isolated from shrimp purchased from seafood market with V. parahaemolyticus strain 474 as host strain. The morphology of phage 474x1 was observed by transmission electron microscopy. One-step growth curve was determined, and its sensitivity to temperature and pH was assessed. The whole genome sequence of 474x1 was analyzed, and a phylogenetic tree was constructed based on the sequence of large subunit of phage terminase. The inhibitory effect of the phage on V. parahaemolyticus in shrimp meat was evaluated using the total colony count method. Results: A lytic phage against V. parahaemolyticus was isolated which named 474x1, and it could lyse 19 out of 23 strains of V. parahaemolyticus (82.61%). The phage had typical characteristics of a tailed bacteriophage in Myoviridae. The optimal multiplicity of infection (MOI) was 0.01, and the one-step growth curve showed that the latent period of 474x1 was 10 min, and the burst size was 115 PFU/cell. The phage was active over a wide range of temperature (30~60 ℃) and pH (4~11). The whole genome of 474x1 was 47830 bp long, and 69 open reading frames were predicted and annotated, including 14 genes with specific functions. Comparative genomics analysis showed that 474x1 had high homology with Vibrio phage Vp41s3, and phylogenetic analysis also indicated that 474x1 was most closely related to the phage Vp41s3. In the application experiment, the number of bacteria in the experimental group with MOI=1000 at 4 ℃ decreased by 0.39 lgCFU/mL compared to the control group at 3 h, while the experimental group with MOI=10000 at 4 ℃ decreased by 0.92 lgCFU/mL compared to the control group at 12 h. At 25 ℃, the number of bacteria in the MOI=1000 and MOI=10000 groups decreased by 1.04 lgCFU/mL and 1.82 lgCFU/mL at 6 h, respectively. The results indicated that phage 474x1 could significantly inhibit the growth of host bacteria in shrimp meat. Conclusion: A new V. parahaemolyticus phage was isolated from shrimp, which had large burst size, short latent period, and showed good stability below 60 ℃ and tolerated a wide range of pH. In addition, the phage had good bacteriostatic effect in food, laying a foundation for the prevention and control of pathogenic strains of V. parahaemolyticus

Erratum on “Probing the kinetics in supramolecular chemistry and molecular assembly by microfluidic-NMR spectroscopy” (Science China Chemistry, (2018), 61, 11, (1460-1464), 10.1007/s11426-018-9293-3)

In the above referenced publication [1], there is a mistake in the Supporting Information. The corrected caption of Figure S2 is: Figure S2 Isothermal titration calorimetry (ITC) data for the titration of 0.125 mM β-CD with 2.5 mM water-soluble viologen derivative (1-dodecyl-1′-methyl-4,4′-bipyridinium bromide iodide, DMV) in an aqueous solution at 25 °C. Based on the ITC result, 4:1 binding stoichiometry of complex C was confirmed. DMV is used as a model guest instead of didodecyl-4,4′-bipyridinium dibromide because the latter cannot be dissolved in water directly. DMV is prepared according to the literature [1].</p

Elucidation of the origin of chiral amplification in discrete molecular polyhedra

Chiral amplification in molecular self-assembly has profound impact on the recognition and separation of chiroptical materials, biomolecules, and pharmaceuticals. An understanding of how to control this phenomenon is nonetheless restricted by the structural complexity in multicomponent self-assembling systems. Here, we create chiral octahedra incorporating a combination of chiral and achiral vertices and show that their discrete nature makes these octahedra an ideal platform for in-depth investigation of chiral transfer. Through the construction of dynamic combinatorial libraries, the unique possibility to separate and characterise each individual assembly type, density functional theory calculations, and a theoretical equilibrium model, we elucidate that a single chiral unit suffices to control all other units in an octahedron and how this local amplification combined with the distribution of distinct assembly types culminates in the observed overall chiral amplification in the system. Our combined experimental and theoretical strategy can be applied generally to quantify discrete multi-component self-assembling systems

Probing the kinetics in supramolecular chemistry and molecular assembly by microfluidic-NMR spectroscopy

Microfluidic-NMR spectroscopy has been extended to study the kinetics in supramolecular chemistry and molecular assembly. Kinetics of a multicomponent host-guest supramolecular system containing viologen derivatives, β-cyclodextrins and cucurbit [7]urils are studied by a PMMA based microfluidic chip combined with a dedicated transmission line probe for NMR detection. By combining microfluidic technology with NMR spectroscopy, the amount of material required for a full kinetic study could be minimized. This is crucial in supramolecular chemistry, which often involves highly sophisticated and synthetically costly building blocks. The small size of the microfluidic structure is crucial in bringing the time scale for kinetic monitoring down to seconds. At the same time, the transmission line NMR probe provides sufficient sensitivity to work at low (2 mM) concentrations.</p

Elucidation of the origin of chiral amplification in discrete molecular polyhedra

\u3cp\u3eChiral amplification in molecular self-assembly has profound impact on the recognition and separation of chiroptical materials, biomolecules, and pharmaceuticals. An understanding of how to control this phenomenon is nonetheless restricted by the structural complexity in multicomponent self-assembling systems. Here, we create chiral octahedra incorporating a combination of chiral and achiral vertices and show that their discrete nature makes these octahedra an ideal platform for in-depth investigation of chiral transfer. Through the construction of dynamic combinatorial libraries, the unique possibility to separate and characterise each individual assembly type, density functional theory calculations, and a theoretical equilibrium model, we elucidate that a single chiral unit suffices to control all other units in an octahedron and how this local amplification combined with the distribution of distinct assembly types culminates in the observed overall chiral amplification in the system. Our combined experimental and theoretical strategy can be applied generally to quantify discrete multi-component self-assembling systems.\u3c/p\u3