Fragmentation Behavior and Ionization Potentials of Aluminum Clusters Al_n(n≤40)

Al2-Al40 clusters were studied by means of the all-electron DFT method. The properties of the aluminum clusters including binding energy, the second difference in energy, HOMO-LUMO gap, especially fragmentation energies and ionization potentials, were analyzed. The main products from the dissociations of aluminum cluster ions are shown to be Al ＋ Al^＋n-1 for the larger clusters, and Al^＋ ＋Aln-1 for the smaller ones. And, the calculated ionization potentials are consistent with the experiment data.

Behavioral fragmentation of waterfowl habitat and its landscape ecological design in Shuangtai-hekou Reserve,Liaoning,China

Behavioral fragmentation of wildlife habitat is discussed. Using “buffer” module in ARC/INFO, behavioral fragmentation habitat of Red crowned crane, Saunders gull, Oriental white stork and Siberian white crane was calculated in the Shuangtai hekou National Reserve, Liaoning Province, China. The result showed that breeding Red crowned crane, Siberian white crane and breeding Saunders gull are very sensitive to fragmentation factors. Suitable habitat is so little for more than 2000 Saunders gull to breed. The reserve only has a capacity of 38 pairs for breeding Red crowed crane. Two key measures were made. First, dismantles all the abandoned oil wells and recovers the original ecosystem to decrease the fragmentation effect, directly benefit to breeding or migration of Red crowned crane and Oriental white stork. Second, recovers the Suaeda tidal mud flat from artificial shrimp and crab pond in the kernel zone of the reserve to enlarge the habitat area of Saunders gull and Siberian white crane.

Experimental investigation on the characteristics of molten lead–bismuth non-eutectic alloy fragmentation in water

To study the interaction between molten noneutectic alloys and subcooled water during severe nuclear accidents,an experimental investigation was carried out by injecting molten lead–bismuth non-eutectic alloy(LBNE,70%Pb-30%Bi)into the water in a free-fall style using the visualized thermo-hydraulic characteristics in melt coolant interaction(VTMCI)facility.The effects of various experimental parameters,including water temperature,melt temperature,melt penetration velocity,and water depth,on the molten LBNE jet fragmentation characteristics were studied.The research shows that compared with lead–bismuth eutectic,larger fragments,less spherical fragments,and more porous debris beds are generated for LBNE.Higher water or melt temperatures facilitate molten LBNE fragmentation,resulting in higher debris bed sphericity and lower debris bed porosity.A higher melt temperature leads to smaller fragment sizes,except that a cake-like debris bed is formed for very high alloy superheat and very low water subcooling.More approximate spherical particles were generated in the film boiling zone than in the thermal interaction zone.Fragment size decreases with an increase in the melt penetration velocity,but the debris bed porosity and sphericity variation was not obvious.The effect of water depth on molten LBNE fragmentation behavior was not obvious under the current experimental conditions.Compared with other fragmentation theories,the Weber number theory better predicted the fragment volume mean diameter.In addition,a melt-jet behavior mode diagram that describes the competition between the hydrodynamic and thermal interactions and diagrams of debris bed porosity and sphericity that show the influence of thermal factors were analyzed in this study.

Empirical model of concrete block fragment behavior under explosion loads

Concrete structures undergo integral fragmentation under explosion loads. The fragmentation degree and particle-size distribution of concrete blocks under explosion loads must be considered during mining to ensure safety. In this study, the impulse is calculated based on the relationship between overpressure and time, and the impact energy of the explosion wave is obtained based on blast theory. Subsequently, the Mohr-Coulomb shear strength fracture criterion is introduced to determine the ultimate shear stress of the concrete materials, and an empirical model that can effectively calculate the energy consumption of concrete blocks under explosion loads is established. Furthermore, concrete fragments with different particle sizes under explosion scenarios are quantitatively predicted with the principle of energy conservation. Finally, explosion tests with different top standoff distances are conducted, and the concrete fragments after the explosion tests are recovered, sieved, weighed, and counted to obtain experimental data. The effectiveness of the fragment empirical model is verified by comparing the model calculation results with the experimental data. The proposed model can be used as a reference for civil blasting, protective engineering design, and explosion-damage assessment.

Deep chemical identification of phytoecdysteroids in Achyranthes bidentata Blume by UHPLC coupled with linear ion trap-Orbitrap mass spectrometry and targeted isolation

Achyranthes bidentata Blume is widely used as a traditional Chinese medicine with the effects of nourishing the liver and kidneys and strengthening muscles and bones.In this work,a rapid and simple strategy was developed for characterizing phytoecdysteroids by ultra-high-performance liquid chromatography coupled with liner ion trap-Orbitrap mass spectrometry using electrospray ionization in the negative mode.As a result,47 phytoecdysteroids were unambiguously or tentatively characterized.Among them,seven known compounds were identified according to the reference standards along with molecular formula,retention time and fragmentation patterns,while others were mostly potential new compounds.Through targeted isolation,the structures of three new compounds were determined by NMR spectra,which were consistent with LC-MS characterization.The present study provides an efficient method to deeply characterize phytoecdysteroids.