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Environmental DNA (eDNA) analysis is a revolutionary tool for non‐invasive, cost‐effective, and highly sensitive monitoring of species distribution and abundance; however, there remain some uncertainties related to eDNA detection and quantification, as well as limitations in terms of its ecological interpretation. Although these may be elucidated by better understanding the characteristics and dynamics of eDNA, insight into such basic eDNA information has been limited in this decade, contrary to the advancements in eDNA applications targeting various taxa and environments. This review compiled previous findings regarding the characteristics and dynamics of macrobial eDNA and provides insights into how the basic knowledge of eDNA can contribute to the refinement and development of eDNA analysis for biomonitoring and stock assessment. A literature survey revealed that studies on the cellular and molecular state of eDNA were particularly lacking (18/728 papers from 2008 to 2020), resulting in a limited understanding regarding the process of eDNA transport and degradation. This review highlighted a number of studies targeting various types of eDNA beyond short mitochondrial DNA fragments (nuclear eDNA, longer eDNA fragments, and larger eDNA particles) to show how information on the state of eDNA improves the reliability of species detection and accuracy of abundance estimation, as well as provide more detailed information on individuals other than their presence and abundance. Linking the state of eDNA to its application will advance the analysis of eDNA and improve its application as a tool for monitoring biodiversity, ecosystem function, and fisheries resources.

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The Na 2 O flux method was successfully applied in the single crystal synthesis of the magnetoplumbite-type strontium ferrite with La-Co co-substitution (Sr 1−x La x Fe 12−y Co y O 19), which is a familiar base material for commercial permanent magnets. The initial amount of Na 2 O flux was fixed in the molar ratio of Na/(Sr+La) = 5.17. Composition analysis revealed discordance between La and Co concentrations (x > y) in the obtained crystals, indicating that the extra charge introduced by the Co 2+ substitution for Fe 3+ is not compensated by La 3+ for Sr 2+. In the present growth condition, the necessary amount of La is nearly twice that of Co (y/x ≃ 0.55), suggesting valence instability of an appreciable amount of Fe 3+ to Fe 2+. Single crystalline magnetization measurements showed that the substitution markedly enhances the magnetic anisotropy and slightly raises the saturation magnetization. Remaining problems, which should be resolved before the experimental determination of the Co site occupation, are also discussed.

The adaptive array under directionally constrained minimization of power (DCMP) algorithm is improved by adding a "pseudonoise." It is effective to protect the desired signal from cancellation or distortion in such cases as 1) where a coberent interference is incident, or 2) where the desired signal direction for the constraint contains some pointing error, or 3) when the desired signal is broad band. The optimum amount of pseudonoise to be added is also discussed and its formula is given. This system is named "tamed adaptive antenna" since its killing capability is somewhat moderated so as not to hurt the desired signal.

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To specify preferential occupation sites of Co substituents and to clarify charge and spin states of Co ions in (La, Co)-cosubstituted hexagonal magnetoplumbite-type (M-type) Sr ferrite Sr1−xLaxFe12−yCoyO19 (x, y ≤ 0.4), 57 Fe and 59 Co nuclear magnetic resonance (NMR) spectra are measured under zero and external magnetic fields using powdered and single crystalline specimens. For comparison, NMR investigations of non-doped and La-or Co-doped M-type Sr ferrites are also performed. Ferrimagnetic M-type Sr ferrite contains the following five crystallographic Fe sites: the majority spin sites 12k, 2a, and 2b, and the minority spin sites 4f1 and 4f2. Based on 57 Fe and 59 Co NMR, a plausible model of (La, Co)-codoped Sr ferrite is deduced. To a considerable degree, the charge compensation between La 3+ and Co 2+ works in the equal (La, Co)-codoped case, where more than half of the Co ions are considered to be present in the minority spin 4f1 sites at the center of the oxygen tetrahedra, with the S=3/2 state carrying a small orbital moment owing to spin-orbit interaction. The remaining small number of high-spin Co 2+ (S=3/2, L=1) ions with unquenched orbital moments would be distributed to the other octahedral 12k, 2a, and 4f2 sites.

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