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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.

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.