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A large number of archaeological wooden building poles have been excavated from the Hai Menkou site (Yunnan province, China). Lignin can be transformed and altered accompanied with significant loss of carbohydrates during this process. Elucidation of chemical and structural transformations of lignin is of primary importance for understanding both the nature of degradation processes and the structure of waterlogged archaeological wood, and crucial for developing proper consolidation technology and restoring artifacts of historical and cultural value. In this study, state-of-the-art analytical techniques, including SEM, FT-IR, XRD, CP-MAS 13 C NMR, 2D-HSQC NMR, 31 P-NMR, CRM, GPC and TG analysis, were all employed to elucidate the structural characteristics of lignin in waterlogged and reference Pinus wood. The results interpreted by NMR analysis demonstrated the depolymerization of lignin via cleavage of β- O -4, β-5, −OCH 3 and some LCC linkages, leading to a higher amount of free phenol OH groups in the lignin from the ancient waterlogged wood as compared to that of the reference wood. Microscopically, it was found that extensive degradation of carbohydrates in cell walls was mainly occurred in secondary cell walls, while the lignin concentrations were relatively increased in CCML and S regions in the plant cell wall of the ancient wood. [ABSTRACT FROM AUTHOR]

Background: The China-Myanmar border region presents a great challenge in malaria elimination in China, and it is essential to understand the relationship between malaria vulnerability and population mobility in this region. Methods: A community-based, cross-sectional survey was performed in five villages of Yingjiang county during September 2016. Finger-prick blood samples were obtained to identify asymptomatic infections, and imported cases were identified in each village (between January 2013 and September 2016). A stochastic simulation model (SSM) was used to test the relationship between population mobility and malaria vulnerability, according to the mechanisms of malaria importation. Results: Thirty-two imported cases were identified in the five villages, with a 4-year average of 1 case/year (range: 0–5 cases/year). No parasites were detected in the 353 blood samples from 2016. The median density of malaria vulnerability was 0.012 (range: 0.000–0.033). The average proportion of mobile members of the study population was 32.56% (range: 28.38–71.95%). Most mobile individuals lived indoors at night with mosquito protection. The SSM model fit the investigated data (χ2 = 0.487, P = 0.485). The average probability of infection in the members of the population that moved to Myanmar was 0.011 (range: 0.0048–0.1585). The values for simulated vulnerability increased with greater population mobility in each village. Conclusions: A high proportion of population mobility was associated with greater malaria vulnerability in the China-Myanmar border region. Mobile population-specific measures should be used to decrease the risk of malaria re-establishment in China. [ABSTRACT FROM AUTHOR]

Yunnan in SW China is a world renowned hotspot for diverse species of vascular plants such as ferns. However, fossil records of the Cenozoic ferns there are insufficient to clarify their phylogeny and historical biogeography from a geological perspective. Among these derived ferns, the monogeneric family Oleandraceae, with a pantropic distribution, is natural and distinctive; however, its origin and evolution remains unknown because of the absence of fossil records. In this study, we identified a new fossil species belonging to the genus Oleandra cav. (Oleandraceae s. s.) from the upper Miocene of Yunnan, China based on a detailed comparison of morphologically similar genera and within this genus. Oleandra bangmaii sp. n. is characterised by a simple fertile frond with an entire cartilaginous margin. Moreover, the venation system in this genus is unique and comprises a prominent midrib along with parallel, closely-spaced secondary free veins. The sori are dorsally borne, with round kidney-shaped indusia. It represents the first fossil occurrence of the genus Oleandra (Oleandraceae) within its extant distribution, suggesting that its fossil history has persisted for at least 10 Ma in Asia. Our finding, together with other existing evidence, suggests that the crown of eupolypods I (the node including families Oleandraceae, Davalliaceae and Polypodiaceae) has diversified and that the climate and vegetation of Yunnan have remained relatively stable since the late Miocene. [ABSTRACT FROM AUTHOR]