Orientation Bias of Self-Assembled Alkanes and Their Derivatives Under Dynamic Lateral Nanoconfinement Conditions

Self-assembled molecular networks(SAMNs)formed on crystalline solid substrates result from the spontaneous arrangement of individual molecules into structured patterns.The interaction between molecules and the substrate leads to a nonrandom orientation of SAMNs with respect to the substrate’s lattice.In the case of graphite,the sixfold rotational symmetry of the substrate results in an equivalent rotational degeneracy in the orientation of SAMNs.In this study,we explored how nanoconfinement,that is,the restriction of SAMN formation to nanometersized areas,known as nanocorrals,could impact and potentially alleviate the orientational degeneracy of SAMNs,with emphasis on the influence of molecule symmetry,size,and intermolecular interactions.To this end,we investigated the orientation distribution of n-alkanes and functionalized alkanes within nanocorrals,which were fabricated using scanning tunneling microscopy lithography(nanoshaving).We observed lifting of orientational degeneracy for long alkanes,contrary to shorter alkanes,which did not exhibit this orientation preference.Notably,functionalized alkanes with hydrogen bonding groups demonstrated preferential alignment regardless of length,highlighting the significance of stabilizing intermolecular interactions in the alignment process.This study discussed the underlying principles of the molecular packing process and shed light on the complexity of molecular self-assembly in nanoconfined spaces.

Experimental investigation on hard rock fragmentation of inserted tooth cutter using a newly designed indentation testing apparatus

This investigation aims to explore the effects of stress conditions and rock cutting rates on hard rock fragmentation through indentation tests on a newly designed triaxial testing apparatus.This apparatus was designed to realize a triaxial loading and indentation test of cylindrical specimens using inserted tooth cutter.The boreability and crushing efficiency of granite rock was investigated by analyzing the change rules of the thrusting force,penetration depth,characteristics of chippings and failure patterns.Several quantitative indexes were used to evaluate rock boreability in this investigation.The granite rock samples all had a chiselled pit and a crushed rock core.Under initial stress conditions,only flat-shape chippings were stripped from the rock surface when the thrusting force reached 20 kN.The rock cutting special energy had a close correlation with the initial stress conditions and inserted tooth shape.Moreover,a thrusting force prediction model was proposed in this paper.The contribution of this study is that for the first time the influence mechanism of the initial triaxial stress conditions on rock fragmentation is investigated using an inserted tooth and the newly designed testing apparatus.This study has a crucial importance for practical underground hard rock crushing in geoengineering.

Study on energy output rule on attenuation of small diameter charge detonation wave passing by air-gap

In order to study energy output rule on attenuation of small diameter charge detonation wave passing by air-gap,the detonation shock wave pressures of different charge diameters and confinements,which are attenuated in air-gap,are measured by using the manganin piezoresistance method.Thus the experiential attenuation rule of X booster explosive is obtained with confinement of 45# steel and polymethyl methacrylate(PMMA),the experiential relational expressions in charge diameter and air-gap thickness are gained.The results indicate that exponential rule is obtained in accordance with attenuation of small diameter charge detonation wave passing by air-gap,and the bigger charge diameter,the smaller modulus decay.By changing air-gap thickness,the detonation pressure is also changed.The detonation performance can be controlled by adjusting charge dimension,confinement and air-gap thickness.