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In this paper, a new microstrip stepped-impedance hairpin resonator with interdigital capacitor (IDC) slow-wave band-pass filter (BPF) using dielectric supported air-gapped microstrip line (DAML) of surface micromachining on GaAs substrate is proposed. Unlike conventional slow-wave filters, the proposed bandpass filters are designed to produce a narrow passband at the fundamental mode of the resonators with small size and a sharp skirt characteristic. The proposed slow-wave band-pass filter with IDC is designed to produce a passband of 7.7% at the fundamental frequency of 56 GHz. It shows insertion loss of 3.37 dB, return loss of better than 15 dB, and a stopband characteristic greater than 31 dB within 37.03–45.51 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1244–1247, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21667

A new microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) using aperture is proposed. This filter has the advantages of compact size and easy fabrication. Also, it provides a very sharp cutoff-frequency response with low insertion loss of 0.13 dB and wide-stopband characteristic. The filter is useful for many microwave-system applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 517–520, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21033

In this paper, a new microstrip stepped-impedance hairpin resonator (SIHR) slow-wave bandpass filter (BPF) using a dielectric-supported air-gapped microstrip line (DAML) via surface micromachining on GaAs substrate is proposed. The slow-wave periodic structures utilize the parallel- and series-resonance characteristics of the resonators to construct a band-pass filter. The proposed slow-wave band-pass filter is designed to produce a passband of 10% at the fundamental frequency of 60 GHz. It exhibits insertion loss of 2.23 dB, return loss of better than 15 dB, and a stopband greater than 35 dB. This filter is useful for many millimeter-wave system applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 86–89, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21089

In this paper, a new microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) using a defected ground structure (DGS) is proposed. The proposed SIR hairpin low-pass filter using DGS provides a very sharp cutoff frequency response with low insertion loss. Furthermore, the SIR hairpin low-pass filter can provide attenuation poles for the wide-stopband characteristic due to the resonance characteristic of the DGS. Design parameters for the SIR low-pass filter are derived based on stepped-impedance theory and the equivalent-circuit model for the DGS. The experimental results show excellent agreement with the theoretical simulation results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 405–408, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21364

Parasin I is a potent 19-residue antimicrobial peptide isolated from the skin mucus of wounded catfish (Parasilurus asotus). Here we describe the mechanism of parasin I production from histone H2A in catfish skin mucosa on epidermal injury. Cathepsin D is found to exist in the mucus as an inactive proenzyme (procathepsin D), and a metalloprotease, induced on injury, cleaves procathepsin D to generate active cathepsin D. This activated form of cathepsin D then cleaves the Ser19-Arg20 bond of histone H2A to produce parasin I. Immunohistochemical analysis reveals that unacetylated histone H2A, a precursor of parasin I, and procathepsin D are present in the cytoplasm of epithelial mucous cells and that parasin I is produced on the mucosal surface on epidermal injury. Western blot analysis shows that parasin I is also present in the skin mucus of other fish species. Furthermore, parasin I shows good antimicrobial activity against fish-specific bacterial pathogens. Taken together, these results indicate that cathepsin D and a metalloprotease participate in the production of parasin I from histone H2A and that parasin I contributes to the innate host defense of the fish against invading microorganisms.