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Base-promoted transition-metal-free α -alkylation of ketones with alcohols is an efficient, practical, and green method for the formation of new C C bonds. Here, we present a DFT study on NaOH/KOH-promoted selective autocatalyzed α -alkylation of ketones with alcohols. For the production of alkylated alcohol, the disodium alkoxide species Na1D is the mediator, and the transformation involves four stages: (I) aldehyde formation; (II) aldol condensation; (III) chalcone reduction to generate an alkylated ketone and an aldehyde; and (IV) reduction of the alkylated ketone to produce an alkylated alcohol. Stage I only occurs at the beginning of the reaction, and the subsequent reaction proceeds via the catalytic cycle cyc-Na involving stages II, III, and IV. The energetic span and the turnover frequency (TOF) of cyc-Na are 35.2 kcal/mol and 5.7 × 10 - 7 1/s, respectively. For the production of alkylated ketone, the dipotassium alkoxide species K1D is the mediator, and the transformation includes dioxygen-assisted oxidation of alkylated alcohol (stage V) and the above four stages. Stage I only takes place initially, too, but the subsequent reaction has two selectable channels. The main channel is the catalytic cycle cyc-K consisting of stages II and III. The energetic span and the TOF of cyc-K are 29.5 kcal/mol and 8.8 × 10 - 5 1/s, respectively. The side channel involves stages II, III, IV, and V, in which the apparent activation energy (AAE) is 34.1 kcal/mol. The calculations present the TOF-determining intermediates and the TOF-determining transition state, and uncover the essence of autocatalysis and the origins of the product selectivity. One important finding is the alkylated ketone selectivity may be enhanced by adding a small quantity of aldehyde corresponding to the alcohol reactant and lowering the reaction temperature.

Theoretical models and numerical simulations suggest that high mass star (with mass > 8 solar mass) can be formed either via monolithic collapse of a massive core or competitive accretion, but the dominant mechanism is currently unclear. Although recent high resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have detected physical and kinematic features, such as disks, outflows and filamentary structures surrounding the high mass young stellar objects (HMYSO), direct detection of the infalling gas towards the HMYSO is still the key to distinguish the different scenarios. Chemically fresh gas inflows have been detected towards low-mass stars being formed, which are consistent with the accretion-disk-outflow process. In this work we report the detection of a chemically fresh inflow which is feeding HMYSO growth in the nearby high mass star-forming region G352.63-1.07. High quality images of the dust and molecular lines from both ALMA and the Submillimeter Array (SMA) have consistently revealed a gravitationally-controlled gas inflow towards a rotating structure (disk or torus) around the HMYSO. The HMYSO is also observed to have an outflow, but it can be clearly separated from the inflow. These kinematic features provide observational evidence to support the conjecture that high-mass stars can be formed in a similar process to that observed in the low-mass counterparts. The chemically fresh infalling streamers could also be related with the disk configuration, fragmentation and accretion bursts that occur in both simulations and observations.

We report the detection of a chemically fresh inflow that is feeding high-mass young-stellar-object (HMYSO) growth in the nearby high-mass star-forming region G352.63 made with both the Atacama Large Millimeter/submillimeter Array (ALMA) and the Submillimeter Array (SMA). High-quality images of the dust and molecular lines from both ALMA and SMA have consistently revealed a gravitationally controlled cold (∼10 K) gas inflow of chemically fresh molecules (e.g., CCH and HC3N) toward the central HMYSO and its surrounding dense gas structure, which has a possible torus- or disk-like morphology. The HMYSO is also observed to have an outflow, which is nearly perpendicular to the torus and its parental filament, and thus can be clearly separated from the inflows. These kinematic features provide observational evidence to support the conjecture that the infalling streamers in high-mass star-forming regions could proceed in a similar process to that observed in low-mass counterparts. The chemically fresh infalling streamers could also be involved in the disk or torus configuration, fragmentation, and accretion bursts that occur in both simulations and observations.

For revealing the influences of thermomigration effect (TM) on the creep properties of interconnecting solder joints in electronic packaging industry, the creep behavior of Cu/Sn0.7Cu/Cu solder joints were researched under temperature gradient of 1043°C/cm and isothermal temperature of 100°C(median temperature) with different shear stress, respectively. It is approved that the creep lifetime of the solder joints is largely reduced under TM effect and this trend is more evident with shear stress increasing. It is also affirmed that since the creep fracture position shifts from the center to the hot end in the solder joints compared with that under isothermal temperature, this suggests that the mechanical properties in the solder joints are nonuniform. The degradation of the creep properties of the solder joints induced by TM effect will bring a new reliability issue in electronic packaging industry.

The research of microfluidic chip requires a series of auxiliary devices. The price of the instruments for microfluidic chip is relatively high, and these instruments may not meet the requirements of each study. So, it is very necessary to reform or develop some auxiliary devices. A simple and controllable gas control device was developed to control the PDMS pneumatic-activated micro valve in the present study. A group of components purchased from the market were assembed as the device, and the whole process was extremely simple. The performance of the device was tested on a pneumatic-activated micro valve chip. The results demonstrated that the developed device worked very well and can control the micro valve in the chip.

Microfluidic chip is the most active field and frontier of μTAS. In comparison to other aspects of research on microfluidic chips, the work on sample pretreatment units are in the preliminary stage. In this study, a microfluidic device for DNA Extraction by ImpetiCbead was devised and fabricated. The chip was used for DNA extraction from Human lymphocytes. The results demonstrated that the extracting effect was comparative basically with the method by the kit of ImpetiCbead. It might be integrated in a complex DNA analysis chip in the future.

Microfluidic chip is the most active field and frontier of μTAS. In comparison to other aspects of researches on microfluidic chips, the work on sample pretreatment units are in the preliminary stage. In this study, a microfluidic device for extraction was devised and fabricated. The extraction efficiency of the microfluidic device was investigated by two phase fluid 0.1% Rhodamine-B aqueous solution and Hexyl alcohol. The results demonstrated that the microfluidic chip worked well in the first two days and might be integrated in a complex chip as a potential tool for sample pretreatment.

A new method for controlling the steering and trajectory of the electric mobile robot is proposed. In order to control the robot’s position and heading, the path error and the heading error of the robot are taken into the control closed loop. On the basis of the self-adaptive PID control method combined with preview theory and fuzzy logic, a trajectory tracking control system is designed. Finally, experiments and simulation are conducted to test the control system. Both experimental and simulation results show that the mobile robot can approach the target trajectory quickly and then move along it, which confirm the validity and the efficiency of the trajectory tracking control system.

Exhaust manifold is the main heated part of the engine, which bears the alternating heat loads and vibration loads in the process of high speed rotation in the extremely bad working environment. According to the method of fluid-solid coupling, the temperature, stress, strain and failure process of the exhaust manifold is reproduced through Abaqus finite element analysis and practical fatigue failure analysis. Comparing the simulation results with the real situation, it is proved that the finite element model is reasonable and the solving conditions are accurate. The further study of the problem will provide theoretical basis for the subsequent materials and structure optimization of the exhaust manifold, which will have important reference for the thermal fatigue damage, life prediction and control under the high temperature and thermal shock.

In the past few years, we have performed a 22 GHz H2O maser survey towards hundreds of BGPS sources using the 25-meter Nanshan Radio Telescope (NSRT) of the Xinjiang Astronomical Observatory, and detected more than one hundred masers. Our aim is to study star formation activities associated with these sources, as well as search for any correlations that may exist between 22 GHz H2O masers and the evolutionary stage of high-mass star formation regions. The NSRT has been upgraded and have now an effective diameter of 26 meter. Besides, cryogenically cooled dual-beam receiver systems covering seven millimeter-wave observing bands have been installed on the NSRT. For the next step of maser observation, we will continue to do H2O and SiO masers survey of massive dust clumps and monitor some maser sources.

The FAD3000/50 safety valve is researched that is newly developed by Zhengzhou Coal Mining Machinery Group Co.,Ltd with high water-based pressure ultra great current capacity. The mathematical model is fistly established according to the study of its structure and the practical system on hydraulic support. The simulation computation has carried under the MATLAB software, and this simulation model has confirmed through the test result. After a comparison of multiple sets of simulation results, the influence of primary structure parameter’s change in safety valve to dynamic characteristics is gived.

The conical spring is one critical part of DANA MHR-3200 series Transmission, its structure is compact and it has good stability and used for bearing larger load and vibration attenuation. Using SolidWorks Simulation to conduct simulation analysis for the stiffness and modality of conical spring, acquire the deformation law of spring under service load, the stiffness curve with nonlinear characteristics, the first four orders natural frequencies and its modal shape, which will lay a foundation for the RE design of conical spring and provide basis for its reconfiguration and repair after lose efficacy.