Laboratory Observations of Linkage of Preslip Zones Prior to Stick-Slip Instability.

Field and experimental observations showed that preslip undergoes a transition from multiple to single preslip zones, which implies the existence of linkage of preslip zones before the fault instability. However, the observations of the linkage process, which is significant for understanding the mechanism of earthquake preparation, remains to be implemented due to the limitations of observation methods in previous studies. Detailed spatiotemporal evolutions of preslip were observed via a high-speed camera and a digital image correlation method in our experiments. The normalized length of preslip zones shows an increase trend while the normalized number of preslip zones (NN) shows an increase followed by a decrease trend, which indicate that the expansion of the preslip undergoes a transition from increase to linkage of the isolated preslip zones. The peak NN indicates the initiation of the linkage of preslip zones. Both the linkage of the preslip zones and the decrease in the normalized information entropy of fault displacement direction indicate the reduction of spatial complexity of preslip as the instability approaches. Furthermore, the influences of dynamic adjustment of stress along the fault and the interactions between the asperities and preslip on the spatial complexity of preslip were also observed and analyzed.

Growth inhibition against intracranial C6 glioma cells by stereotactic delivery of BCNU by controlled release from poly(D,L-lactic acid) nanoparticles.

Transferrin (Tf), an iron-transporting serum glycoprotein, which binds to receptors expressed at the surface of most proliferating cells with particularly high expression on erythroblasts and cancer cells, was chosen as the ligand to develop BCNU-loaded biodegradable poly(D,L-lactic acid) nanoparticles (NPs) containing a ligand, which specifically binds to glioma cells, and their anti-tumor ability was evaluated using a C6 glioma model. In vitro drug release behavior demonstrated that BCNU-loaded PLA NPs show certain sustained release characteristics. NPs with low molecular weight PLA showed a higher burst effect and a significantly faster drug release from PLA samples. The biodistribution of Tf-coated nanoparticles investigated by 99Tc-labeled SPECT showed that the surface-containing transferrin PLA nanoparticles were concentrated in the brain and no radioactive foci could be found outside the brain. Inhibition of tumor growth in the C6 tumor-bearing animal model showed that BCNU-loaded PLA NPs had stronger cytotoxicity and prolonged the average survival time of rats. Especially when treated at an early stage with a higher dosage of NPs, the average survival time of rats was prolonged 88.37%. Furthermore, one rat maintained normal behavior continuously for an observation period of up to 60 days.