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Objective This study was conducted to generate single stranded DNA oligonucleotides with selective affinity to bovine spermatozoa, assess its binding potential and explore its potential utility in trapping spermatozoa from suspensions. Methods A combinatorial library of 94 mer long oligonucleotide was used for systematic evolution of ligands by exponential enrichment (SELEX) with bovine spermatozoa. The amplicons from sixth and seventh rounds of SELEX were sequenced, and the reads were clustered employing cluster database at high identity with tolerance (CD-HIT) and FASTAptamer. The enriched nucleotides were predicted for secondary structures by Mfold, motifs by Multiple Em for Motif Elicitation and 5′ labelled with biotin/6-FAM to determine the binding potential and binding pattern. Results We generated 14.1 and 17.7 million reads from sixth and seventh rounds of SELEX respectively to bovine spermatozoa. The CD-HIT clustered 78,098 and 21,196 reads in the top ten clusters and FASTAptamer identified 2,195 and 4,405 unique sequences in the top three clusters from the sixth and seventh rounds, respectively. The identified oligonucleotides formed secondary structures with delta G values between −1.17 to −26.18 kcal/mol indicating varied stability. Confocal imaging with the oligonucleotides from the seventh round revealed different patterns of binding to bovine spermatozoa (fluorescence of the whole head, spot of fluorescence in head and mid- piece and tail). Use of a 5′-biotin tagged oligonucleotide from the sixth round at 100 pmol with 4×106 spermatozoa could trap almost 80% from the suspension. Conclusion The binding patterns and ability of the identified oligonucleotides confirms successful optimization of the SELEX process and generation of aptamers to bovine spermatozoa. These oligonucleotides provide a quick approach for selective capture of spermatozoa from complex samples. Future SELEX rounds with X- or Y- enriched sperm suspension will be used to generate oligonucleotides that bind to spermatozoa of a specific sex type.

This paper discusses the validation of Modal/method of MoMents (MoM) including cases when the apertures are made as big as the wall of the enclosure (equivalent to having one side of the cavity open). The validation is done using field computations involving bodies of arbitrary shape (FEKO), a commercially available code. The results show that Modal/MoM predicts the results close to the analytical results of Robinson et al. Electron. Lett., 32 (17), 1996; Robinson et al., IEEE Trans. Electromagn. Compat., 40 (3), 240-247, 1998 for single-aperture cases and for most double-aperture cases. Also, for the cases of considering oblique incident plane waves, through validation, it has been found that Modal/MoM can predict the shielding effectiveness close to measured results for smaller angles and not for larger angles of incidence due to the edge effects. In this work, the shielding effectiveness is calculated at only one point, the center of the cavity assuming it to be the worst case. This work discovers the limitation of Modal/MoM for certain applications. Index Terms--FEKO, MoM, shielding effectiveness, validation.

An electromagnetic susceptibility test within an ideal reverberation chamber is numerically simulated using the moment method (MM). The random field environment within the chamber is synthesized using a superposition of plane waves that are propagating in fixed directions determined rigorously from spectral sampling theory. Randomness is introduced in the complex field amplitudes associated with each plane wave. This approach yields field statistics within a designated test region that approach ideal. Moreover, the fixed propagation directions allow very efficient calculation of the currents induced at specific test points on an equipment-under-test due to the random field realizations. MM calculations show that the proposed sampling method yields a better prediction of the statistics of the induced current while requiring far less computation time than the currently used technique of superimposing randomly propagating plane waves to yield field realizations. [ABSTRACT FROM AUTHOR]