Role of the mechanical microenvironment in cancer development and progression

Cross-talk between tumor cells and mechanical stress in the tumor microenvironment has been shown to be involved in carcinogenesis.High mechanical stress in tumors can alter the metabolism and behaviors of cancer cells and cause cancer cells to attain cancer stem-like cell properties,thus driving tumor progression and promoting metastasis.The mechanical signal is converted into a biochemical signal that activates tumorigenic signaling pathways through mechanotransduction.Herein,we describe the physical changes occurring during reprogramming of cancer cell metabolism,which regulate cancer stem cell functions and promote tumor progression and aggression.Furthermore,we highlight emerging therapeutic strategies targeting mechanotransduction signaling pathways.

Virtual Reconstruction of Long Bone Fracture in Car-to-pedestrian Collisions Using Multi-body System and Finite Element Method

Lower limb injures are frequently observed in passenger car traffic accidents.Previous studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics,which lack in-depth study on the fractures in stress analysis.This paper aims to investigate lower limb impact biomechanics in real-world car to pedestrian accidents and to predict fractures of long bones in term of stress parameter for femur,tibia,and fibula.For the above purposes,a 3D finite element(FE) model of human body lower limb(HBM-LL) is developed based on human anatomy.The model consists of the pelvis,femur,tibia,fibula,patella,foot bones,primary tendons,knee joint capsule,meniscus,and ligaments.The FE model is validated by comparing the results from a lateral impact between simulations and tests with cadaver lower limb specimens.Two real-world accidents are selected from an in-depth accident database with detailed information about the accident scene,car impact speed,damage to the car,and pedestrian injuries.Multi-body system(MBS) models are used to reconstruct the kinematics of the pedestrians in the two accidents and the impact conditions are calculated for initial impact velocity and orientations of the car and pedestrian during the collision.The FE model is used to perform injury reconstructions and predict the fractures by using physical parameters,such as von Mises stress of long bones.The calculated failure level of the long bones is correlated with the injury outcomes observed from the two accident cases.The reconstruction result shows that the HBM-LL FE model has acceptable biofidelity and can be applied to predict the risk of long bone fractures.This study provides an efficient methodology to investigate the long bone fracture suffered from vehicle traffic collisions.

Proposal and Verification of Simultaneous Measurement Method for Three Thermoelectric Properties with Film-Type Thermocouple Probe

A new simultaneous measurement method for the measurement of the three thermoelectric properties with a film-type thermocouple probe was proposed. Seebeck coefficient was measured using the steady-state condi-tion of the differential method. The electrical resistivity was measured us-ing the four-probe method and the thermal diffusivity is measured using the periodic heating method. The effectiveness of the proposed method was verified using constantan as a reference material. After describing the effectiveness of the method, the measurement of three thermoelectric properties of Bi0.3Sb1.7Te3, which is a thermoelectric material, was per-formed.

Targeting the mechano-microenvironment and liver cancer stem cells:a promising therapeutic strategy for liver cancer

Over the past 2 decades,cancer stem cells(CSCs)have been identified as the root cause of cancer occurrence,progression,chemoradioresistance,recurrence,and metastasis.Targeting CSCs is a novel therapeutic strategy for cancer management and treatment.Liver cancer(LC)is a malignant disease that can endanger human health.Studies are increasingly suggesting that changes in the liver mechanical microenvironment are a primary driver triggering the occurrence and development of liver cancer.In this review,we summarize current understanding of the roles of the liver mechano-microenvironment and liver cancer stem cells(LCSCs)in liver cancer progression.We also discuss the relationship between the mechanical heterogeneity of liver cancer tissues and LCSC recruitment and metastasis.Finally,we highlight potential mechanosensitive molecules in LCSCs and mechanotherapy in liver cancer.Understanding the roles and regulatory mechanisms of the mechano-microenvironment and LCSCs may provide fundamental insights into liver cancer progression and aid in further development of novel therapeutic strategies.

Microscale Infrared Observation of Liquid-Vapor Phase Change Process on the Surface of Porous Media for Loop Heat Pipe

Loop Heat Pipe (LHP) performance strongly depends on the performance of a wick that is porous media inserted in an evaporator. In this paper, the visualization results of thermo-fluid behavior on the surface of the wick with microscopic infrared thermography were reported. In this study, 2 different samples that simulated a part of wick in the evaporator were used. The wicks were made by different two materials: polytetrafluoroethylene (PTFE) and stainless steel (SUS). The pore radii of PTFE wick and SUS wick are 1.2 μm and 22.5 μm. The difference of thermo-fluid behavior that was caused by the difference of material was investigated. These two materials include 4 different properties: pore radius, thermal conductivity, permeability and porosity. In order to investigate the effect of the thermal conductivity on wick’s operating mode, the phase diagram on the q-keff plane was made. Based on the temperature line profiles, two operating modes: mode of heat conduction and mode of convection were observed. The effective thermal conductivity of the porous media has strong effect on the operating modes. In addition, the difference of heat leak through the wick that was caused by the difference of the material was discussed.

Dynamics and geometry of developing planar jets based on the invariants of the velocity gradient tensor

Based on the direct numerical simulation （DNS）, the developing planar jets under different initial conditions, e.g., the con- ditions of the exit Reynolds number and the exit mean velocity profile, are investigated. We mainly focus on the characteristics of the invariants of the velocity gradient tensor, which provides insights into the evolution of the dynamics and the geometry of the planar jets along with the flow transition. The results show that the initial flow near the jet exit is strongly predominated by the dissipation over the enstrophy, the flow transition is accompanied by a severe rotation and straining of the flow elements, where the vortex structure evolves faster than the fluid element deformation, in the fully-developed state, the irrotational dissipation is dominant and the most probable geometry of the fluid elements should remain between the biaxial stretching and the axisymmetric stretching. In addition, with a small exit Re and a parabolic profile for the exit mean streamwise velocity, the decay of the mean flow field and the magnitude of the turbulent variables will be strengthened in the process of the flow transition, however, a large exit Re will promote the flow transition to the fully-developed state. The cross-impact between the exit Re and the exit mean velocity profile is also observed in the present study.

Integrated in-process chatter monitoring and automatic suppression with adaptive pitch control in parallel turning

Simultaneous processes such as parallel turningor milling offer great opportunities for more efficientmanufacturing because of their higher material removalrates. To maximize their advantages, chatter suppressiontechnologies for simultaneous processes must be devel-oped. In this study, we constructed an automatic chattersuppression system with optimal pitch control for shared-surface parallel turning with rigid tools and a flexibleworkpiece, integrating in-process chatter monitoring basedon the cutting force estimation. The pitch angle betweentwo tools is tuned adaptively in a position control system inaccordance with the chatter frequency at a certain spindlespeed, in a similar manner as the design methodology forvariable-pitch cutters. The cutting force is estimatedwithout using an additional external sensor by employing amulti-encoder-based disturbance observer. In addition, thechatter frequency is measured during the process by per-forming a low-computational-load spectrum analysis at acertain frequency range, which makes it possible to cal-culate the power spectrum density in the control system ofthe machine tool. Thus, the constructed system for automatic chatter suppression does not require any addi-tional equipment.

VISUALIZATION OF TURBULENT REACTIVE JET BY USING DIRECT NUMERICAL SIMULATION

Direct numerical simulation(DNS)of turbulent planar jet with a second-order chemical reaction(A+B→R)is performed to investigate the processes of mixing and chemical reactions in spatially developing turbulent free shear flows.Reactant A is premixed into the jet flow,and reactant B is premixed into the ambient flow.DNS is performed at three different Damk¨ohler numbers(Da=0.1,1,and 10).Damk¨ohler number is a ratio of a time scale of a flow to that of chemical reactions,and in this study,the large Da means a fast chemical reaction,and the small Da means a slow chemical reaction.The visualization of velocity field shows that the jet flow is developed by entraining the ambient fluid.The visualization of concentration of reactant A shows that concentration of reactant A for Da=1 and 10 becomes very small in the downstream region because the chemical reaction consumes the reactants and reactant A is diffused with the jet development.By comparison of the profiles of chemical reaction rate and concentration of product R,it is found that product R for Da=10 is produced by the chemical reaction at the interface between the jet and the ambient fluids and is diffused into the jet flow,whereas product R for Da=0.1 is produced in the jet flow after reactants A and B are well mixed.