A method for the determination of a-1-fetoprotein (AFP) in human serum by using a horseradish peroxidase (HRP) label in an enzymelinked immunosorbent assay (ELISA) is proposed. The method is based on the electrochemical determination of enzymatic reaction product with differential pulse voltammetry at a gold disk electrode. The assay consists of two successive steps. The ®rst step is a conventional HRP-mediated ELISA for the formation of electroactive 2,2 H -diaminoazobenzene by means of the o-phenylenediamine2 2H 2 O 2 2 2HRP system. At the second step, 2,2 H -diaminoazobenzene exhibits a sensitive voltammetric response at À0.19 V in pH 2.0 PBS. The peak current is proportional to the concentration of AFP in the range of 0.5±400 ngymL (R 0.9993) under optimum conditions. The sensitivity of this method is higher than that of the traditional spectrophotometric ELISA procedure. The proposed method has been applied to the clinical determination of AFP in human serum with satisfactory precision and accuracy.
The classical problem of a viscoelastic circular cylinder under its own weight is analysed in the Hamiltonian system. On the basis of the theory of state space for axisymmetric problems and the application of dual variables of stresses, the technology of variable separation can be used. Hence the fundamental solutions, zero eigenfunctions and non-zero eigenfunctions, are derived. Because of the integrity of the solution space, various boundary conditions can be described by certain combinations general eigenfunctions. By using the adjoint symplectic relations, the eigenfunction expansion approach is applied to satisfying the boundary conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.