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The integrity of the digital image content is very important for special types of images. To better locate tampered regions in the image, this paper proposes a reversible watermarking technology for tamper localization based on SIFT. By dividing the original image into blocks, the feature information of each sub-block is computed as the authentication watermark. The carrier image is then processed to extract the feature region of the image, and the authentication watermark generated by each sub-block is embedded into the corresponding feature region through mapping. When the watermarked image is attacked, the related attack is detected by the invariant moment, and the sub-block feature value and the authentication watermark extracted from the feature region are calculated to determine if the sub-block has been tampered with, and if so, the position of the tampered region is given. The experimental result illustrates this scheme can detect and locate the tamper region effectively and accurately, and the scheme has certain robustness and invisibility. [ABSTRACT FROM AUTHOR]

Unique anatomical and physiological features have made hamster species desirable research models. Comparative genomics and phylogenetic analysis of the hamster family members to clarify their evolution and genetic relationship, can provide a genetic basis for the comprehension of the variable research results obtained using different hamster models. The Syrian golden hamster (Mesocricetus auratus) is the most widely used species. In this study, we sequenced the complete mitochondrial genome (mitogenome) of M. auratus, compared it with the mitogenome of other Cricetinae subfamily species, and defined its phylogenetic position in the Cricetidae family. Our results show that the mitogenome organization, gene arrangement, base composition, and genetic analysis of the protein coding genes (PCGs) of M. auratus are similar to those observed in previous reports on Cricetinae species. Nonetheless, our analysis clarifies some striking differences of M. auratus relative to other subfamily members, namely distinct codon usage frequency of TAT (Tyr), AAT (Asn), and GAA (Glu) and the presence of the conserved sequence block 3 (CSB-3) in the control region of M. auratus mitogenome and other hamsters (not found in Arvicolinae). These results suggest the particularity of amino acid codon usage bias of M. auratus and special regulatory signals for the heavy strand replication in Cricetinae. Additionally, Bayesian inference/maximum likelihood (BI/ML) tree shows that Cricetinae and Arvicolinae are sister taxa sharing a common ancestor, and Neotominae split prior to the split between Cricetinae and Arvicolinae. Our results support taxonomy revisions in Cricetulus kamensis and Cricetulus migratorius, and further revision is needed within the other two subfamilies. Among the hamster research models, Cricetulus griseus is the species with highest sequence similarity and closer genetic relationship with M. auratus. Our results show mitochondrial DNA diversity of M. auratus and other Cricetinae species and provide genetic basis for judgement of different hamster models, promoting the development and usage of hamsters with regional characteristics. [ABSTRACT FROM AUTHOR]

Sn1-xFexO2 (x=0, 1, 2, and 3 mol%) nanoparticles with rutile structure were chemically synthesized by a simple and reproducible uniform precipitation-hydrothermal method. Fe doping hardly changed the morphology of SnO2 nanoparticles, whereas the crystallite size decreased with the increase of Fe content. The results of high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) showed that the incorporation of Fe ions into the SnO2 resulted in lattice shrinkage and significant structural dislocation. X-ray photoelectron spectroscopy (XPS) revealed the presence of Fe3+ and Fe2+ in SnO2 nanoparticles, as well as the relative content of oxygen vacancies (VO) and tin interstitials (Sni) in the doping system. The optical band gap was found to decrease from 3.67 to 3.43 eV with an increase in Fe doping. Photoluminescence spectra (PL) further confirmed the existence of oxygen vacancies by studying defect levels in the forbidden zone. Magnetization measurements showed that Fe-doped samples exhibit the coexistence of ferromagnetic and paramagnetic behavior at room temperature. The ferromagnetic contribution may be attributed to the long-range ferromagnetic order produced by the interaction of a large number of bound magnetic polarons. Importantly, the saturation magnetization varied with the relative content of oxygen vacancies in the materials, and the saturation magnetization of 3% Fe-doped SnO2 nanoparticles with the highest VO/Sni value was up to 5.13×10−3 emu/g. [ABSTRACT FROM AUTHOR]

Ni-doped SnO2 dilute magnetic semiconductors were prepared by precipitation method. The obtained spherical nanoparticles are pure tetragonal rutile phase, and Ni ions promote the growth of SnO2 nanoparticles. The optical band gap energy of the SnO2 nanoparticles decreases from 3.14 to 2.84 eV when input x% Ni. The room-temperature photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) confirm the existence of surface oxygen vacancies caused by the large specific surface area and the introduction of Ni ions. All the synthesized Ni-doped SnO2 nanoparticles achieve room-temperature ferromagnetism, with a saturation magnetization of up to 2.95 × 10−3 emu/g at a dopant concentration of 2%. The interaction between oxygen vacancies and Ni2+ realizes the magnetic transition of nanoparticles from diamagnetic to ferromagnetic. [ABSTRACT FROM AUTHOR]

Two trinuclear oxo-centered iron(III) complexes [Fe3(μ3-O)Salox(L1)5(MeOH)2] (1) and [Fe3(μ3-O)Salox(L1)5(EtOH)2]·2EtOH·2H2O (2) (Salox = salicylaldoxime, L1 = o-nitrobenzoic acid) have been synthesized, and their X-ray crystal structures, spectroscopic properties (IR, UV-Vis, fluorescence), and magnetic properties have been characterized. In each complex, the three Fe(III) centers of the [Fe3O] moieties are joined together by a μ3-O unit to form an isosceles triangle, and each metal center has a distorted octahedral coordination geometry. The fluorescence emission intensities for the two complexes are much higher than those of the free proligands, suggesting that the [Fe3O] structural unit increases the rigidity of the ligands after coordination, and the enlarged conjugate system reduces the frontier orbitals energy gap. The nature of magnetic coupling within complexes 1 and 2 indicates both intramolecular strong and intermolecular weak antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]