24,837 research outputs found
Black hole solution and strong gravitational lensing in Eddington-inspired Born-Infeld gravity
A new theory of gravity called Eddington-inspired Born-Infeld (EiBI) gravity
was recently proposed by Ba\~{n}ados and Ferreira. This theory leads to some
exciting new features, such as free of cosmological singularities. In this
paper, we first obtain a charged EiBI black hole solution with a nonvanishing
cosmological constant when the electromagnetic field is included in. Then based
on it, we study the strong gravitational lensing by the asymptotic flat charged
EiBI black hole. The strong deflection limit coefficients and observables are
shown to closely depend on the additional coupling parameter in the
EiBI gravity. It is found that, compared with the corresponding charged black
hole in general relativity, the positive coupling parameter will
shrink the black hole horizon and photon sphere. Moreover, the coupling
parameter will decrease the angular position and relative magnitudes of the
relativistic images, while increase the angular separation, which may shine new
light on testing such gravity theory in near future by the astronomical
instruments.Comment: 14 pages, 7 figures, 1 table. Two issues on the deflection angle and
photon sphere were corrected and clarifie
Recrystallized parylene as a mask for silicon chemical etching
This paper presents the first use of recrystallized
parylene as masking material for silicon chemical etch.
Recrystallized parylene was obtained by melting parylene C at
350°C for 2 hours. The masking ability of recrystallized parylene
was tested in HNA (hydrofluoric acid, nitric acid and acetic acid)
solution of various ratios, KOH (potassium hydroxide) solution
and TMAH (tetramethylammonium hydroxide) at different
temperatures and concentrations. It is found that interface
between parylene and the substrate can be attacked, which
results in undercuts. Otherwise, recrystallized parylene exhibited
good adhesion to silicon, complete protection of unexposed silicon
and silicon etching rates comparable to literature data
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