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The theory for calculation and/or measurement of sound power based on the classical velocity-based radiation mode (V-mode) approach is well established for planar structures. However, the current V-mode theory is limited in scope in that it can only be applied to conventional motion sensors (i.e., accelerometers). In this study, in order to estimate the sound power of vibrating beam and plate structure by using polyvinylidene fluoride (PVDF) films as sensors, a PVDF-based radiation mode (C-mode) approach concept is introduced to determine the sound power radiation from the output signals of PVDF films of the vibrating structure. The proposed method is a hybrid of vibration measurement and numerical calculation of C-modes. The proposed C-mode approach has the following advantages: (1) compared to conventional motion sensors, the PVDF films are lightweight, flexible, and low-cost; (2) there is no need for special measuring environments, since the proposed method does not require the measurement of sound fields; (3) In low frequency range (typically with dimensionless frequency kl < 4), the radiation efficiencies of the C-modes fall off very rapidly with increasing mode order, furthermore, the shapes of the C-modes remain almost unchanged, which means that the computation load can be significantly reduced due to the fact only the first few dominant C-modes are involved in the low frequency range. Numerical simulations and experimental investigations were carried out to verify the accuracy and efficiency of the proposed method.

Merozoite surface antigen 1 (MSA1) is a promising candidate for vaccine development against malaria parasites. Here, we report the complete nucleotide sequence of the gene encoding the precursor to this major surface antigen of Plasmodium berghei strain ANKA using cDNA library screening and polymerase chain reaction techniques. A single open reading frame of 5,376 basepairs encoding a protein with a calculated molecular mass of 197 kD was defined. The protein contains a putative signal peptide of 19 amino acids, a membrane anchor sequence of 18 residues, and shows two epidermal growth factor-like domains rich in Cys residues at the C-terminus. There are four repeat sequences of oligopeptides in the molecule: tetrapeptide (Ser-Thr-Thr-Thr), tripeptide (Pro-Thr-Pro and Pro-Ala-Ala), and dipeptide (Ser-Gly). Furthermore, three nine-residue stretches of a motif (Ala-Ser-Asn-Pro-Gly-Ala-Ser-Ala-Ser) are located near each other. All of these repeat sequences are unexceptionally located in the variable regions when compared with other MSA1 molecules. The molecule displays 79% overall identity to the analogous antigen of P. yoelii yoelii strain YM, 70% to that of P. chabaudi chabaudi strain AS, and 38% to that of P. falciparum strain Wellcome.