The vp28 gene encoding an envelope protein (28 kDa) of white spot syndrome virus (WSSV) was amplified from WSSV-infected tiger shrimp that originated from Malaysia. Recombinant VP28 protein (r-28) was expressed in Escherichia coli and used as an antigen for preparation of monoclonal antibodies (MAbs). Three murine MAbs (6F6, 6H4 and 9C10) that were screened by r-28 antigen-based enzyme-linked immunosorbent assay (ELISA) were also able to recognize viral VP28 protein as well as r-28 on Western blot. Three non-overlapping epitopes of VP28 protein were determined using the MAbs in competitive ELISA; thus, an antigen-capture ELISA (Ac-ELISA) was developed by virtue of these MAbs. Ac-ELISA can differentiate WSSV-infected shrimp from uninfected shrimp and was further confirmed by a polymerase chain reaction (PCR) and Western blot. Approximately 400 pg of purified WSSV sample and 20 pg of r-28 could be detected by Ac-ELISA, which is comparable in sensitivity to PCR assay but more sensitive than Western blot in the detection of purified virus. Hemolymph and tissue homogenate samples collected from a shrimp farm in Malaysia during December 2000 and July 2001 were also detected by Ac-ELISA and PCR with corroborating results.
Thermal cycling failure of solder joints in surface-mount passive components represents a core bottleneck limiting the reliability of next-generation high-frequency communication systems. Conventional microwave dielectric ceramics exhibit low coefficients of thermal expansion (CTE, 5-12 ppm/°C), causing severe thermal mismatch with commercial SAC305 lead-free solder (21.9 ppm/°C) and copper conductors, which generates enormous thermal stress and induces solder joint cracking during temperature cycling. Herein, we report an intrinsically high-CTE microwave dielectric ceramic Na3P3O9 with a CTE of 22.25 ppm/°C, matching almost perfectly with SAC305 solder. At its optimal sintering temperature of 610 °C, this material simultaneously possesses an ultralow permittivity (εr = 4.88) and ultralow dielectric loss (on the order of 10-4). The physical origins of its excellent comprehensive properties are elucidated via crystal structure analysis and chemical bond theory. Finite element simulations reveal that under the standard electronic packaging thermal cycling condition of -40 to 125 °C, the thermal stress of solder joints on Na3P3O9 is only 54% of that on commercial A6M and 30% of that on conventional alumina. A Ku-band broadband dielectric resonator antenna designed using this material achieves an impedance bandwidth of 3.1 GHz and an in-band total efficiency of >87.2%, fully covering the transmit and receive bands of fixed-satellite and broadcasting satellite services and enabling transmit-receive integration for low Earth orbit satellite terminals. This work provides a high-CTE dielectric material system for addressing the solder joint reliability issue in high-frequency passive components.