X.-C. Zhang

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We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a(More)
Cellular proliferation within the ventricular zone (VZ) may contribute to sex differences through the net addition of neurons in song control nuclei. To address this issue, we administered [(3)H]thymidine to Bengalese finches of both sexes, and estradiol benzoate (EB) to females 15 days post hatching. The birds were killed 2h later to examine thymidine(More)
—Polydimethylsiloxane (PDMS) is an important poly-meric material widely used in bio-MEMS devices such as micro-pillar arrays for cellular mechanical force measurements. The accuracy of such a measurement relies on choosing an appropriate material constitutive model for converting the measured structural deformations into corresponding reaction forces.(More)
We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The me-anderline displays(More)
We present novel metamaterial structures based upon various planar wallpaper groups, in both hexagonal and square unit cells. An investigation of metamaterials consisting of one, two, and three unique sub-lattices with resonant frequencies in the terahertz (THz) was performed. We describe the theory, perform simulations, and conduct experiments to(More)
We have fabricated resonant terahertz metamaterials on free-standing polyimide substrates. The low-loss polyimide substrates can be as thin as 5.5 µm yielding robust large-area metamaterials which are easily wrapped into cylinders with a radius of a few millimeters. Our results provide a path forward for creating multi-layer non-planar metamaterials at(More)
We investigate the interaction between terahertz waves and resonant antennas with sub-cycle temporal and λ/100 spatial resolution. Depositing antennas on a LiNbO₃ waveguide enables non-invasive electro-optic imaging, quantitative field characterization, and direct measurement of field enhancement (up to 40-fold). The spectral response is determined over a(More)
  • Kuo-Shen Chen, Arturo A Ayón, Xin Zhang, S Mark Spearing
  • 2009
—The ability to predict and control the influence of process parameters during silicon etching is vital for the success of most MEMS devices. In the case of deep reactive ion etching (DRIE) of silicon substrates, experimental results indicate that etch performance as well as surface morphology and post-etch mechanical behavior have a strong dependence on(More)
The sedative effects of music were evaluated using the bispectral index (BIS) during target-controlled infusion (TCI) propofol. A total of 110 women undergoing hysterectomy were randomly allocated to receive either music or no music. Propofol was administered using target-controlled infusion and the concentration adjusted gradually to achieve an observer's(More)
INTRODUCTION The value of gastric intramucosal pH (pHi) can be calculated from the tonometrically measured partial pressure of carbon dioxide ([Formula: see text]) in the stomach and the arterial bicarbonate content. Low pHi and increase of the difference between gastric mucosal and arterial [Formula: see text] ([Formula: see text] gap) reflect splanchnic(More)