Reconciliation of Theoretical Lifetimes of the 5s5p^(3)P_(2)^(o) Metastable State for ^(88)Sr with Measurement: The Role of the Blackbody-Radiation-Induced Decay

We conducted measurement and calculation to resolve the long-standing large discrepancy in the metastable state lifetime for the ^(88)Sr atom between theoretical and experimental results. The present lifetime τ = 830_(-240)^(+600)s,measured using the magneto-optical trap as a photon amplifier to detect the weak decay events, is approximately60% larger than the previous experimental value τ = 520_(-140)^(+310)s. By considering the electron correlation effects in the framework of the multiconfiguration Dirac–Hartree–Fock theory, we obtained a theoretical lifetime of 1079(54) s, which lies in the range of measurements with error bars. Furthermore, we considered the higher-order electron correlation and Breit interaction to control the uncertainty of the theoretical calculation. The significant improvement in the agreement between calculations and measurements is attributed to the updated blackbody radiation-induced decay rate.

Theoretical calculation of the quadratic Zeeman shift coefficient of the^(3)P_(0)^(o)clock state for strontium optical lattice clock

In the weak-magnetic-field approximation,we derived an expression of quadratic Zeeman shift coefficient of^(3)P_(0)^(o)clock state for^(88)Sr and^(87)Sr atoms.By using this formula and the multi-configuration Dirac-Hartree-Fock theory,the quadratic Zeeman shift coefficients were calculated.The calculated values C_(2)=-23.38(5)MHz/T^(2) for^(88)Sr and the^(3)p_(0)^(o),F=9/2,M_(F)=±9/2 clock states for^(87)Sr agree well with the other available theoretical and experimental values,especially the most accurate measurement recently.In addition,the calculated values of the^(3)p_(0)^(o),F=9/2,M_(F)=±9/2 clock states were also determined in our^(87)Sr optical lattice clock.The consistency with measurements verifies the validation of our calculation model.Our theory is also useful to evaluate the second-order Zeeman shift of the clock transition,for example,the new proposed^(1)S_(0),F=9/2,M_(F)=±5/2-^(3)P_(0)^(o),F=9/2,M_(F)=±3/2 transitions.

FACTORS INFLUENCING FOOD-WASTE BEHAVIORS AT UNIVERSITY CANTEENS IN BEIJING,CHINA:AN INVESTIGATION BASED ON THE THEORY OF PLANNED BEHAVIOR

Food waste is a major social problem that contributes to the overutilization of natural resources,affecting economic progress and environmental protection.Food waste occurs throughout the whole process of the food supply chain,especially during the consumption stage.As a special group of consumers,the emerging adults at university may have unique food consumption patterns and their food waste behavior in university canteens deserves more attention.To understand the influential factors of the food-waste behavior of students in university canteens,a field survey was conducted at China Agricultural University canteen with 705 respondents.Based on the theory of planned behavior,this paper examines the influencing factors of student food-waste behavior from three dimensions:sociopsychological factors,individual characteristics and dining factors.The results indicate that the percentage of students who waste food is relatively low,at roughly 27%.Perceived behavior control,gender,monthly living expenses,BMI,mealtime,meal expectations and food portion were significantly correlated with student food-waste behavior,among which perceived behavior control had the most prominent correlation,followed by food portion.Behavioral intention,household location and palatability were not significantly correlated with student food-waste behavior.Therefore,it is necessary to promote publicity and education on reducing food waste on campus,reinforce the administration of the department of support service,and optimize the food portion in the canteen.

Enhancing alkyne semi-hydrogenation through engineering metal-support interactions of Pd on oxides

Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.

Characterization and Tribological Properties of Graphene/Copper Composites Fabricated by Electroless Plating and Powder Metallurgy

Self-lubricating copper matrix composites reinforced with graphene were prepared by electroless plating and powder metallurgy.The morphology and structure of graphene,Cu@graphene powder,and Cu@graphene/Cu composites were characterized and the tribological properties of Cu@graphene/Cu composites were investigated.The X-ray diffraction pattern of Cu@graphene confirms the coexistence of characteristic peaks of both copper and graphene,with a weakened characteristic peak of carbon impurity.The obtained morphology of Cu@graphene reveals that the surface of the graphene is completely covered with a uniform and compact copper layer with lots of copper nanoparticles.Raman and Fourier transform infrared spectroscopy analyses show that the oxygen functional groups and defects on the surface of the redox graphene can be reduced through the electroless plating process.The tribological results indicate that the coefficient of friction of Cu@graphene/Cu composites initially decreases and then increases with an increase in Cu@graphene content.The lowest coefficient of friction,which is about 29.47% lower than that of pure Cu,is achieved in the Cu@graphene/Cu composites with 3.0 wt%Cu@graphene.The chemical composition and topography of the wear tracks for Cu@graphene/Cu composites infer that the formation of a well-consolidated graphene-rich lubricious tribolayer at the contact surface and a higher microhardness work together to enhance the tribological performance of Cu@graphene/Cu composites.

Enhancing bioactivity and stability of polymer-based materialtissue interface through coupling multiscale interfacial interactions with atomic-thin TiO2 nanosheets

Stable and bioactive material-tissue interface(MTF)basically determines the clinical applications of biomaterials in wound healing,sustained drug release,and tissue engineering.Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials,most are still restricted by their stability and biocompatibility.Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material-tissue interfacial interactions with atomically thin TiO_(2)nanosheets.Resin modified with TiO_(2)nanosheets displays improved mechanical properties,hydrophilicity,and stability.Also,we confirm that this resin can effectively stimulate the adhesion,proliferation,and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell-resin interface model.TiO_(2)nanosheets can also enhance the interaction between demineralized dentinal collagen and resin.Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale.

Analysis of new drug registration and review in China in 2021

In recent years,China's pharmaceutical industry has undergone tremendous changes.The reform of pharmaceutical policies has led to a shift in the direction of drug research and development from generic to innovative,and the sustainable investment from the capital market into the pharmaceutical industry and the return of overseas pharmaceutical talents have together created a boom in drug research and development in China today.