There is still a heavy burden of stomach cancer in China. The incidence and mortality patterns of stomach cancer show substantial gender and regional disparities. Great effort is needed to provide more accessible health services, sufficient financial resources, and adequate cancer-care infrastructure for the Chinese population, especially for people living in rural areas.

In thin films of Bi 2 Se 3 , the isospin sectors have nontrivial topological properties, which are conventionally characterized by the Z 2 index. The generalized isospin Chern number ͓E. Prodan, Phys. Rev. B 80, 125327 ͑2009͔͒ is calculated in the general case where the structural inversion symmetry is broken and the isospin operator ˆz is not conserved. The analytical formalism obtained reveals clearly the connection between the isospin Chern number and the Z 2 index. We further demonstrate that the topological characterization based on the isospin Chern number fully agrees with the characteristic spectrum of the edge states in different regimes.

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Strain engineering is a very effective method to continuously tune the electronic, topological, optical and thermoelectric properties of materials. In this work, strain-dependent phonon transport of recently-fabricated antimonene (Sb monolayers) under biaxial strain is investigated using a combination of first-principles calculations and the linearized phonon Boltzmann equation within the single-mode relaxation time approximation (RTA). It is found that the ZA dispersion of antimonene with strain less than -1% gives imaginary frequencies, which suggests that compressive strain can induce structural instability. Experimentally, it is possible to enhance structural stability by tensile strain. The calculated results show that lattice thermal conductivity increases with strain increasing from -1% to 6%, and lattice thermal conductivity at 6% strain is 5.6 times larger than that at -1% strain at room temperature. It is interesting that lattice thermal conductivity is inversely proportional to the buckling parameter h in a considered strain range. Such a strain dependence of lattice thermal conductivity is attributed to enhanced phonon lifetimes caused by increased strain, while group velocities have a decreased effect on lattice thermal conductivity with increasing strain. It is found that acoustic branches dominate the lattice thermal conductivity over the full strain range. The cumulative room-temperature lattice thermal conductivity at -1% strain converges to a maximum with the phonon mean free path (MFP) at 50 nm, while that at 6% strain becomes as large as 44 μm, which suggests that strain can give rise to very strong size effects on lattice thermal conductivity in antimonene. Finally, the increased lattice thermal conductivity caused by increasing strain can be explained by a reduced polarized covalent bond, inducing weak phonon anharmonicity. These results may provide guidance on fabrication techniques of group-VA element (As, Sb, Bi) monolayers, and offer perspectives on tuning lattice thermal conductivity by the size and strain for applications of thermal management and thermoelectricity.