The sidebands in the solid-state 13C NMR spectra of 13 polycyclic aromatic hydrocarbon compounds associated with kerogen structure were suppressed with cross polarization (CP), magic-angle spinning (MAS), and total sideband suppression (TOSS). The chemical shift values of these model compounds were obtained under various chemical circumstances, which were subsequently used to determine the chemical shifts of aliphatic and aromatic carbons in kerogen structure via CP/MAS/TOSS 13C NMR measurements. Dipolar dephasing (DD) was used to obtain the spectra of nonprotonated carbon, discriminating protonated and nonprotonated carbons in the aromatic cluster. Consequently, the structural parameters for different carbons were characterized. High-resolution solid-state 13C NMR measurements were conducted on a suite of kerogen macromolecules isolated from source rocks originated from the Kuqa depression, Awati River, and Kapusaliang River of the Tarim Basin in northwestern China to develop an NMR-associated method for monitoring the thermal alteration of kerogens. These rocks covered a broad maturity range, as indicated by the R o values of 0.52%−1.81%. Our results suggest that the aromaticity (f a) and aromatic cluster size (χb) are effective parameters for assessment of the thermal evolution of kerogens that resulted from the geological heating process undergone in the ancient sediments.

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In recent years, the Scalable Vocabulary Tree (SVT) has been shown to be effective in image recognition. However, in mobile landmark image recognition where the foreground is the landmark to be recognized while the background is cluttered, the current SVT framework ignores different local importance of image, hence restricting its performance. In this paper, we propose a new landmark recognition framework that can incorporate saliency information to improve the recognition performance relative to the baseline SVT method. Specifically, the saliency information is incorporated in three phases: image descriptor calculation, vocabulary tree generation, and image representation. We constructed a city-scale landmark dataset in Singapore, and the experimental results show that the proposed mobile landmark recognition by incorporating saliency information outperforms the baseline SVT recognition by about 9%.

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The hepatitis delta virus (HDV) is a small (∼1700 nucleotides) RNA pathogen which encodes only one open reading frame. Consequently, HDV is dependent on host proteins to replicate its RNA genome. Recently, we reported that ASF/SF2 binds directly and specifically to an HDV-derived RNA fragment which has RNA polymerase II promoter activity. Here, we localized the binding site of ASF/SF2 on the HDV RNA fragment by performing binding experiments using purified recombinant ASF/SF2 combined with deletion analysis and site-directed mutagenesis. In addition, we investigated the requirement of ASF/SF2 for HDV RNA replication using RNAi-mediated knock-down of ASF/SF2 in 293 cells replicating HDV RNA. Overall, our results indicate that ASF/SF2 binds to a purine-rich region distant from both the previously published initiation site of HDV mRNA transcription and binding site of RNAP II, and suggest that this protein is not involved in HDV replication in the cellular system used.