Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

In order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting,dynamic Brazilian splitting tests were conducted on granite samples after thermal treatment at 25,200,400,and 600℃.Results show that the dynamic peak splitting strength of thermally damaged granite samples increases with increasing strain rate,showing obvious strain‐rate sensitivity.With increasing temperature,thermally induced cracks in granite transform from intergranular cracks to intragranular cracks,and to a transgranular crack network.Thermally induced damages reduce the dynamic peak splitting strength and the maximum absorbed energy while increasing the peak radial strain.The fracture mode of the thermally damaged granite under dynamic loads is mode Ⅱ splitting failure.By using the axial roughness index Z2 a,the distribution ranges of the wedge‐shaped failure zones and the tensile failure zones in the fracture surfaces under dynamic Brazilian splitting can be effectively identified.The radial roughness index Z_(2)^(r)is sensitive to the strain rate and temperature.It shows a linear correlation with the peak splitting strength and the maximum absorbed energy and a linear negative correlation with the peak radial strain.Z_(2)^(r)can be used to quantitatively estimate the dynamic parameters based on the models proposed.

Triangle mechanism in the decay process B_(0)→J/ψK^(0)f_(0)(980)(a_(0)(980))

The role of the triangle mechanism in the decay processes B_(0)→J/ψK^(0)f_(0)→J/ψK^(0)π^(+)π^(-)and B_(0)→J/ψK^(0)a_(0)→J/ψK^(0)π^(0)ηis probed.In these processes,the triangle singularity appears from the decay of B_(0)intoJ/ψ∅K^(0),and then,∅decays intoK^(0)K^(0)andK^(0)K^(0)merged into f_(0)or a_(0),which finally decay intoπ^(+)π^(-)andπ^(0)η,respectively.We find that this mechanism leads to a triangle singularity around M_(inv)(K^(0)f_(0)(a_(0)))≈1520 MeV and gives sizable branching fractions Br(B_(0)→J/ψK^(0)f_(0)→J/ψK^(0)π^(+)π^(-))=7.67×10^(-7)and Br(B_(0)→J/ψK^(0)a_(0)→J/ψK^(0)π^(0)η)=1.42×10^(-7).This investigation can help us obtain the information of the scalar mesonf_(0)(980)or a_(0)(980).

Dynamically reconfigurable subwavelength optical device for hydrogen sulfide gas sensing

The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable.Herein,a lithography-free,wide-angle,and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated,based on a reversible nanochemistry approach.The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide(CuO)thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas.Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90%at the wavelength of 1.79μm with the initial thickness of CuO taken as 150 nm.Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure,which show good agreement with experimental results.We believe that the proposed versatile approaches can be implemented for dynamic control management,allowing applications in tunable photonics,active displays,optical encryption,and gas sensing.