Thermoelastic analysis of multiple defects with the extended finite element method

In this paper, the extended finite element method (XFEM) is adopted to analyze the interaction between a single macroscopic inclusion and a single macroscopic crack as well as that between multiple macroscopic or microscopic defects under thermal/mechanical load. The effects of different shapes of multiple inclusions on the material thermomechanical response are investigated, and the level set method is coupled with XFEM to analyze the interaction of multiple defects. Further, the discretized extended finite element approximations in relation to thermoelastic problems of multiple defects under displacement or temperature field are given. Also, the interfaces of cracks or materials are represented by level set functions, which allow the mesh assignment not to conform to crack or material interfaces. Moreover, stress intensity factors of cracks are obtained by the interaction integral method or the M-integral method, and the stress/strain/stiffness fields are simulated in the case of multiple cracks or multiple inclusions. Finally, some numerical examples are provided to demonstrate the accuracy of our proposed method.

An Analytical Solution for Wave Propagation in a Pipe Pile with Multiple Defects

An analytical solution is developed in this paper to conduct the low-strain integrity testing for a pipe pile with multiple defects.The derived solution allows simulating the pipe pile as a three-dimensional model by considering the wave propagation in the vertical,circumferential and radial directions.Analytical solutions of the pile are obtained by the Laplace transform and separation of variables.Accordingly,time-domain responses of the solution are deduced by the inverse Fourier transform numerically.The solution is validated against the published solutions for an intact pile and a pile with a single defect.Parametric studies are conducted to identify and characterize the velocity responses on the top of pipe piles with multiple defects.Numerical results suggest that the reflected waves generated by the deep defects are affected by the secondary reflections from the shallow defects.A new detecting method is proposed to decrease the influence of high-frequency interferences and to predict the defective depth,which suggests putting the receiver at the point of 90°along the circumferential direction.

Novel biallelic TRNT1 mutations lead to atypical SIFD and multiple immune defects

Mutations in the gene encoding transfer RNA(tRNA)nucleotidyltransferase,CCAadding 1(TRNT1),an enzyme essential for the synthesis of the 30-terminal CCA sequence in tRNA molecules,are associated with a rare syndrome of congenital sideroblastic anemia,B cell immunodeficiency,periodic fevers,and developmental delay(SIFD).Clinical manifestations and immunological phenotypes were assessed in a Chinese patient with novel compound heterozygous mutations in TRNT1.The patient required multiple hospitalizations starting at the age of 2 years for recurrent fevers without an infective cause.During the febrile episode,the patient was found to have microcytic hypochromic anemia,B cell lymphopenia,and hypogammaglobulinemia.Targeted gene sequencing identified novel compound heterozygous mutations in the TRNT1 gene(c.525delT,p.Leu176X;c.938T>C,p.Leu313Ser).Immunophenotyping revealed increased CD8^+T cells,CD4^+ terminally differentiated effector memory helper T lymphocytes(CD4 TEMRA),and CD4^+ effector memory lymphocytes(CD4 EM).Analysis of CD4^+T subsets identified decreased T follicular helper cells(Tfh)with a biased phenotype to Th2-like cells.The patient also showed a lower percentage of switched memory B(smB)cells.Additionally,defects in the cytotoxicity of the patient’s NK andγτT cells were shown by CD107alpha expression.In conclusion,TRNT1 mutations may lead to multiple immune abnormality especially humoral and cytotoxicity defects,which indicate that SIFD is not only suffered‘Predominantly antibody deficiencies’in IUIS classification system,and further studies are needed to understand the pathogenesis of immunodeficiency in these patients.

Properties of single and multiple defect modes in one-dimensional photonic crystals containing left-handed metamaterials

Wave propagation is studied in structures consisting of alternate left- and right-handed layers. Bragg gap and zero-n gap appear in different frequency regions of the structure. The periodicity of the structure is broken by simply reversing the order of the layers in one half of the structure, resulting in defect modes located inside the zero-n gap and Bragg gap. These modes can be made very narrow by adding more layers in the structure. The defect mode located inside the zero-n gap is sensitive to the symmetry of the structure and insensitive to the angle of incidence of the incoming radiation. Multiple modes are also generated inside the gaps by repeating the structural pattern. Thus, a simple structure can be used for single and multiple modes that are imDortant for different applications.