  Topological one-dimensional superconductors can sustain in their extremities
zero energy modes that are protected by different kinds of symmetries. The
observation of these excitations in the form of Majorana fermions is one of the
most intensive quests in condensed matter physics. Their study is not only
interesting in itself, but also because they have promising applications in the
area of quantum computation. In this work we are interested in another class of
one dimensional topological systems, namely topological insulators. These also
present symmetry protected end modes with robust properties and do not require
the low temperatures necessary for topological superconductivity. We consider
the simplest kind of topological insulators, namely chains of atoms with
hybridized $sp$ orbitals. We study the transport properties of these chains in
the trivial, non-trivial topological phases and at the quantum topological
transition. We use a simple device consisting of two semi-infinite hybridized
$sp$-chains connected to a quantum dot and obtain the thermoelectric properties
of this system as a function of temperature and distance to the topological
transition. We show that the electrical conductance and the Wiedemann-Franz
ratio of the device at the topological transition have universal values at very
low temperatures. The thermopower gives direct evidence of fractional charges
in these systems.
