Engineering The Neck Hinge Reshapes The Processive Movement of Kinesin-3

Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.

Application of modified discontinuous deformation analysis to dynamic modelling of the Baige landslide in the Jinsha River

Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.

Rapid onset hazards,fault-controlled landslides and multi-method emergency decision-making

Numerous large-scale fragmented bedrock landslides developed along major fault system is a world-wide phenomenon,which are often characterized with repeated reactivation throughout histories.Due to the large-scale and deep-seated features,it is normally difficult to control such landslides,which in turn pose great threat to local residents and infrastructures.Therefore,monitoring and forecasting these gigantic landslides has become a key protocol for risk reduction.This paper introduces such a typical massive landslide,named Yahuokou landslide,besides Min River in Zhouqu County,Gansu Province,China.Reactivated on July 16,2019 with a volume of approximately 4×106 m3,moving slowly and transitionally starting from top part,its toe had partially blocked the Min River and destroyed roads and houses eventually by August 11,2019.As to emergency response for such huge slowmoving landslide,there is no standard national protocols.Therefore,how to make effective emergency decision has become a challenge.Based on previous experiences,integrated multi-methods,including UAV imagery interpretation,we applied GNSS monitoring and field investigations in the early stages of landsliding,in order to assist the decisionmaking.The results show that the movement path of the current displacement is consistent with that of the 1989 reactivation event,and the slide body was separated into three relatively independent blocks with different sliding velocities and responses to rainfall.The upper and lower blocks appeared less affected by rainfall,while the middle block responded more to the changes in precipitations.It proves that the combined approaches using a variety of monitoring techniques can play an effective role in the monitoring of rapidly deformed transitional largescale landslides,and can also provide a set of reference methods for the emergency disposal of similar landslide hazards.

An estimation model for the fragmentation properties of brittle rock block due to the impacts against an obstruction

Mountain hazards with large masses of rock blocks in motion – such as rock falls, avalanches and landslides – threaten human lives and structures. Dynamic fragmentation is a common phenomenon during the movement process of rock blocks in rock avalanche, due to the high velocity and impacts against obstructions. In view of the energy consumption theory for brittle rock fragmentation proposed by Bond, which relates energy to size reduction, a theoretical model is proposed to estimate the average fragment size for a moving rock block when it impacts against an obstruction. Then, different forms of motion are studied, with various drop heights and slope angles for the moving rock block. The calculated results reveal that the average fragment size decreases as the drop height increases, whether for free-fall or for a sliding or rolling rock block, and the decline in size is rapid for low heights and slow for increasing heights in the corresponding curves. Moreover, the average fragment size also decreases as the slope angle increases for a slidingrock block. In addition, a rolling rock block has a higher degree of fragmentation than a sliding rock block, even for the same slope angle and block volume. Finally, to compare with others' results, the approximate number of fragments is estimated for each calculated example, and the results show that the proposed model is applicable to a relatively isotropic moving rock block.

Study on the pattern and mode of vertical crustal deformation during the seismogenic process of intraplate strong earthquakes

In this paper,the data of vertical crustal deformations associated with the Xingtai,Haicheng,Tangshan and Datong strong earthquakes in North China Block have been processed,analyzed and studied.The result shows that the seismogenic processes of strong earthquakes are accompanied by an evolution of crustal deformation as follows: ① The area of crustal deformation anomaly should be large in radius and extensive in range. ② There are both the 'field' and 'source' of crustal deformation anomaly,with the 'source' existing inside the'field' but differing from the 'field' distinctly. ③ The evolution process includes a number of steps.Firstly, movements in the 'field region transform from the normal state to an anomalous state to start the formation of field precursors.Secondly,movements in the 'source' region become outstandingly remarkable. Thirdly,anomalies in the 'field' region that surrounds the 'source' become increasingly intense.Fourthly,the 'source' region enters a state of immobilized-movement.Finally,an earthquake occurs. ④ There are usually one or more areas where the anomaly field forms a special pattern,mostly a four-quadrant distribution.The area which is'activated' first but becomes 'immobilized' afterwards often coincides with the source area.⑤ The appearance of an obviously immobilized area inside the obviously activated area is a precursory feature which suggests that an earthquake is impending.⑥ The longer the duration of immobilized-movement,the higher the magnitude of earthquake would be.The above might be the basic mode of vertical crustal deformation during the seismogenic process of strong intraplate earthquakes.

Subduction and retreating of the western Pacific plate resulted in lithospheric mantle replacement and coupled basin-mountain respond in the North China Craton

The North China Craton(NCC) witnessed Mesozoic vigorous tectono-thermal activities and transition in the nature of deep lithosphere. These processes took place in three periods:(1) Late Paleozoic to Early Jurassic(~170 Ma);(2) Middle Jurassic to Early Cretaceous(160-140 Ma);(3) Early Cretaceous to Cenozoic(140 Ma to present). The last two stages saw the lithospheric mantle replacement and coupled basin-mountain response within the North China Craton due to subduction and retreating of the Paleo-Pacific plate, and is the emphasis in this paper. In the first period,the subduction and closure of the PaleoAsian Ocean triggered the back-arc extension, syn-collisional compression and then post-collisional extension accompanied by ubiquitous magmatism along the northern margin of the NCC. Similar processes happened in the southern margin of the craton as the subduction of the Paleo-Tethys ocean and collision with the South China Block. These processes had caused the chemical modification and mechanical destruction of the cratonic margins. The margins could serve as conduits for the asthenosphere upwelling and had the priority for magmatism and deformation. The second period saw the closure of the Mongol-Okhotsk ocean and the shear deformation and magmatism induced by the drifting of the Paleo-Pacific slab. The former led to two pulse of N-S trending compression(Episodes A and B of the Yanshan Movement) and thus the pre-existing continental marginal basins were disintegrated into sporadically basin and range pro vince by the Mesozoic magmatic plutons and NE-SW trending faults.With the anticlockwise rotation of the Paleo-Pacific moving direction, the subduction-related magmatism migrated into the inner part of the craton and the Tanlu fault became normal fault from a sinistral one. The NCC thus turned into a back-arc extension setting at the end of this period. In the third period, the refractory subcontinental lithospheric mantle(SCLM) was firstly remarkably eroded and thinned by the subduction-induced asthenospheric upwelling, especially those beneath the weakzones(i.e.,cratonic margins and the lithospheric Tanlu fault zone). Then a slightly lithospheric thickening occurred when the upwelled asthenosphere got cool and transformed to be lithospheric mantle accreted(~125 Ma) beneath the thinned SCLM. Besides, the magmatism continuously moved southeastward and the extensional deformations preferentially developed in weak zones, which include the Early Cenozoic normal fault transformed from the Jurassic thrust in the Trans-North Orogenic Belt, the crustal detachment and the subsidence of Bohai basin caused by the continuous normal strike slip of the Tanlu fault, the Cenozoic graben basins originated from the fault depression in the Trans-North Orogenic Belt, the Bohai Basin and the Sulu Orogenic belt. With small block size, inner lithospheric weak zones and the surrounding subductions/collisions, the Mesozoic NCC was characterized by(1) lithospheric thinning and crustal detachment triggered by the subduction-induced asthenospheric upwelling.Local crustal contraction and orogenesis appeared in the Trans-North Orogenic Belt coupled with the crustal detachment;(2)then upwelled asthenosphere got cool to be newly-accreted lithospheric mantle and crustal grabens and basin subsidence happened, as a result of the subduction zone retreating. Therefore, the subduction and retreating of the western Pacific plate is the outside dynamics which resulted in mantle replacement and coupled basin-mountain respond within the North China Craton. We consider that the Mesozoic decratonization of the North China Craton,or the Yanshan Movement, is a comprehensive consequence of complex geological processes proceeding surrounding and within craton, involving both the deep lithospheric mantle and shallow continental crust.