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Self-regulation effect (SRE) is a unique phenomenon in laser blown powder directed energy deposition (DED), which can dynamically compensate the sloping deposition surface (within an acceptable tolerance) induced by the fluctuation of the fabricating process or part warpage. For this reason, the layer-thickness is varying in DED and strongly dependent on SRE determined by the powder standoff distance (PSD) and the inter-layer temperature (ILT), especially for cantilever structures easily deformed. However, previous numerical studies on the thermo-mechanical analyses of DED usually adopt a fixed layer-thickness, missing the reality of the printing process and impairing the credibility and prediction accuracy of simulation. In this study, an improved modelling process considering SRE in DED is proposed to enhance the high-fidelity simulation. Two single-walls were firstly fabricated by DED on the baseplates clamped as cantilevers, to quantify the relationship between the deposited layer-thickness and PSD based on in-situ measurement. Meanwhile, the relationship between ILT and the difference value of the deposited layer-thickness under different inter-layer dwell times also was investigated by combining simulations with experiments. Next, two 3D coupled thermo-mechanical finite element (FE) models with and without SRE were established to examine the proposed modelling strategy. Finally, the thermo-mechanical responses and the geometric dimension predicted by the two models were compared with experimental data. The results illustrate that, compared with the traditional model without SRE, the proposed model significantly improves the mechanical and geometric predictions of the DED parts.

Near-equiaxed β grain was achieved in the near-α Ti60 (Ti-5.7Al-4.0Sn-3.5Zr-0.4Mo-0.4Si-0.4Nb-1.0Ta-0.05C) titanium alloy via laser directed energy deposition (LDED). The microstructural evolution along the building direction and the room-temperature tensile properties along the horizontal and vertical directions (building direction) were systematically studied through SEM and OM. EBSD and XRD were utilized to accurately demonstrate the texture of the α and β phases. The results showed that the α phase presented a low texture intensity, which was ascribed to the weak textured β grain with near-equiaxed morphology, since there are Burgers orientation relationships during the β→α transition. In addition, numerical simulation, combined with the CET curve of Ti60 alloy considering the effect of multi-composition, was utilized to elucidate the formation mechanism of the near-equiaxed β grains. Furthermore, according to the solidification theory, we proposed that the solidification temperature range Δ T f was more accurate than the growth restriction factor Q in predicting the formation tendency of equiaxed β grain in different titanium alloys. Tensile results showed that the horizontal and vertical samples had similar strength, while the former exhibited larger elongation than the latter. The effect of the near-equiaxed β grain and the internal α phase on mechanical properties were revealed at last.

We demonstrate the fabrication of a flexible and conductive bioelectrode via the electrodeposition of IrO2 nanoparticles on a metalized polypropylene micromembrane (PPMM). The metalized PPMM is prepared by carrying out conformal electroless deposition of Au on individual polypropylene (PP) fibers of PPMM using both polydopamine and polyvinyl alcohol as the surface–modifying agents to improve the hydrophilicity of PPMM. Images from scanning and transmission electron microscopes, as well as analysis from energy dispersive X–ray spectrometer and X–ray photoelectron spectroscopy confirm the successful formation of IrO2 nanoparticles on individual PP fibers of metalized PPMM. For bio–stimulating purpose, the IrO2–coated PPMM reveals an impressive charge–storage–capacity of 54.6 mC/cm2 in cyclic voltammetry, In addition, under a symmetric bi–phasic current pulse, its charge–injection–capacity reaches 466 μC/cm2. Since the entire constituents for the IrO2–coated PPMM are bio−compatible, we envision its potential use as a bioelectrode in implantable biomedical devices.

Although TiO2 is a wide band gap semiconductor, it demonstrates photodegradation activity under visible light irradiation after dye sensitization. Compared with esterification between the surface hydroxyl group of TiO2 and the carboxylic group of dyes, electrostatic interaction between TiO2 and dye shows better photosensitized performance. In this work, Bi/Al co-doping anatase titania (Ti1-xBi2x/3Al2x/3O2 (0 ≤ x ≤ 0.3)) is designed to enhance the electrostatic interaction. The effect of Al ions is to enhance the solubility of Bi3+ into titania nanocrystals. A new band gap is generated after high concentration of Bi element doping, which not only promotes the absorption of visible light, but also improves the utilization of photogenerated carriers. Based on the results of transmission electron microscopy, light absorption, photodegradation activity and density functional theory calculations, it is found that bismuth dopant is the electron capture site. It first accumulates electrons through photocatalytic degradation reaction to enhance electrostatic adsorption between the catalyst and the positively charged dye molecules, and finally realizes high-efficiency photosensitization degradation of Rhodamine B. In addition, the sensitized titania has excellent photodegradation recyclability.

We demonstrate a facile and seedless wet chemical process to deposit RuO2 thin film on a glass slide. The process entails the use of dopamine and its oxidized form, polydopamine (PDA), as the reducing and chelating agent, as well as the adhesive agent bonding the RuO2 and glass slide. The formula starts with the oxidation of K2RuCl5 to prepare RuO4 solution, followed by its reduction by dopamine to form chelated RuO2 colloids for the deposition of amorphous RuO2 thin film containing 26.5 at% hydrous RuO2 and 73.5 at% RuO2. After a mild Ar annealing, the RuO2 thin film exhibits a rutile phase with (110) preferred orientation. Elemental analysis indicates incomplete pyrolysis of PDA. Results from X-ray absorption spectroscopy confirm the presence of RuO4 and its transformation to RuO2. Electrochemical analysis of the adsorbed dopamine molecules on an ITO substrate validates the oxidative behavior of dopamine. The bonding strength of RuO2 thin film is determined by a tape-peeling test in which both the as-deposited and annealed RuO2 thin films show robust adhesion to the glass substrate.

This paper designs an improved model predictive control (MPC) strategy for the flow field in a transonic wind tunnel to quickly mitigate the overshoot and smooth the input and output signals under model uncertainty. A flow field control model is established first, followed by model discretization and the general MPC structure. Then, an MPC robust tuning approach is presented, which includes a bending temporal matrix design, and an adaptive robust temporal tuning algorithm. The bending temporal matrix is proposed to reduce the variability in the input profile in the temporal domain by penalizing high-frequency components, thus indirectly smoothing the input and output trajectories. The proposed adaptive robust temporal tuning algorithm can obtain an optimal tuning ratio by maximizing the control performance index of the system under model uncertainty. Simulation results show that the improved MPC controller yields better performance than a traditional MPC controller in mitigating the overshoot and smoothing the input profiles.

Direct C(sp3)-H functionalization of N-unprotected aliphatic amines represents one of the most efficient and straightforward strategies for amine synthesis. Despite some recent progress in this field, the NH2-directed γ-C(sp3)-H arylation of primary aliphatic amines except α-amino esters remained an unmet challenge. In this report, we established a simple and efficient method for site-selective C(sp3)-H arylation of primary aliphatic amines by aryl iodides. In the presence of only 5 mol% Pd(OAc)2, a wide range of aliphatic amines including O-benzyl and O-silyl amino alcohols were arylated at γ- or δ-positions by aryl iodides containing a broad scope of functional groups. The synthetic application of this method had also been demonstrated by large-scale synthesis, the synthesis of a fingolimod analogue, and the conjugation with natural d -menthol and fluorescent 1,8-naphthalimide.

We developed a predictive model for the pipeline friction in the 520–730 m3/h transmission range using the multi-layer-perceptron–back-propagation (MLP–BP) method and analyzing the unit friction data after the pigging of a hot oil pipeline. In view of the shortcomings of the MLP–BP model, two optimization methods, the genetic algorithm (GA) and mind evolutionary algorithm (MEA), were used to optimize the MLP–BP model. The research results were applied to the standard friction prediction of three sections of a hot oil pipeline. After the GA and MEA optimizations, the average errors of the three sections were 0.0041 MPa for the GA and 0.0012 MPa for the MEA, and the mean-square errors were 0.083 and 0.067, respectively. The MEA-BP model prediction results were characterized by high precision and small dispersion. The MEA-BP prediction model was applied to the analysis of the wax formation 60 and 90 days after pigging. The analysis results showed that the model can effectively guide pipe pigging and optimization. There was little sample data for the individual transmission and oil temperature steps because the model was based on actual production data modeling and analysis, which may have affected the accuracy and adaptability of the model.

In this study, a novel mixed-mode online solid-phase extraction (SPE) method was developed to recover miscellaneous trace organic contaminants (TrOCs) from environmental water samples. Six kinds of sorbents, including C