Mixed anion control of enhanced negative thermal expansion in the oxysulfide of PbTiO3.

The rare physical property of negative thermal expansion (NTE) is intriguing because materials with a large NTE over a wide temperature range can serve as high-performance thermal expansion compensators. However, the applications of NTE are hindered by the fact that most of the available NTE materials show small magnitudes of NTE, and/or NTE occurs only in a narrow temperature range. Herein, for the first time, we investigated the effect of anion substitution instead of general Pb/Ti-site substitutions on the thermal expansion properties of a typical ferroelectric NTE material, PbTiO3. Intriguingly, the substitution of S for O in PbTiO3 further increases the tetragonality of PbTiO3. Consequently, an unusually enhanced NTE with an average volumetric coefficient of thermal expansion of V = -2.50 × 10-5 K-1 was achieved over a wide temperature range (300-790 K), which is in contrast to that of pristine PbTiO3 (V = -1.99 × 10-5 K-1, RT-763 K). The intensified NTE is attributed to the enhanced hybridization between Pb/Ti and O/S atoms by the substitution of S, as evidenced by our theoretical investigations. We therefore demonstrate a new technique for introducing mixed anions to achieve a large NTE over a wide temperature range in PbTiO3-based ferroelectrics.

Agro-ecological product and its value realization pathway.

The value realization of agro-ecological products is of great significance to China's food security, ecological protection, and strategic blueprint. We reviewed the concepts and boundaries of agricultural ecosystem and agro-ecological products (including agricultural products, other ecosystem services and dis-services). Based on the emergy method, the agricultural ecosystem service quantification method was proposed and the ecosystem services and dis-services of typical agricultu-ral products per unit area in China were calculated. Further, the type-specific values realization pathways of the agro-ecological products were discussed. It was found that 1) the values of the agro-ecological products, which has been realized through market mechanism, can further be added by the means of increasing green degrees or special degree, and establishing agricultural industrial chains; 2) the values of the agro-ecological products, which have not yet been realized through market mechanism, should be compensated or realized through ecological product empowerment and regional shared brand quality commitment; 3) the values of the agro-ecological products can be preserved or increased through reducing the harmfulness of N, P, pesticides and insecticides to ecosystem and human health by multi-approaches-based GHG emission reduction, land nutrient management strategies, and rational landscape architecture; 4) some financial solutions can be promoted, e.g., cancellation of secondary agricultural subsidies, the establishment of ecological trading platform and the certification of ecological products. This study contributes to propose the value realization pathways of agro-ecological products, advance the development of green finance, and promote the modernization of natural resource management capabilities.

[Genetic diversity and phylogenetic analysis of Fusarium oxysporium strains isolated from the Cucurbitaceae hosts revealed by SRAPs]. / ç“œç±»æž¯èŽç— èŒé—ä¼ å¤šæ ·æ€§å’Œäº²ç¼˜å ³ç³»çš„SRAP分析.

Cucurbitaceae wilt of different hosts could be caused by Fusarium oxysporum. To clear the genetic diversity and phylogenetic relationship of F. oxysporum isolates from different Cucurbitaceae hosts and regions, genomic DNA of ninety-five strains of F. oxysporum isolated from different hosts and different regions were amplified by sequence-related amplified polymorphism (SRAP) molecular markers. All strains could be uniquely distinguished with 238 polymorphism bands which generated 100% of polymorphic ratio with 19 selective primer pairs. On average, each primer pairs amplified 12.5 loci and 12.5 polymorphic loci. A total of 166 bands of F. oxysporum f. sp. momordicae (FOM) were amplified, among which 145 polymorphic bands generated 87.4% of polymorphic ratio. On average, each primer combination amplified 8.7 loci and 7.7 polymorphic loci. This indicated that genetic variation of F. oxysporum was extensive. The genetic similarity coefficient of F. oxysporum was 0.68-0.99, and the average indexes of Nei's genetic diversity and Shannon were 0.2390 and 0.3718, respectively. Ninety-five strains of F. oxysporum were divided into four formae speciales from bitter gourd, cucumber, watermelon and melon, when the genetic similarity coefficient was 0.74. In SRAP dendrogram all the FOM isolates were gathered into one phylogenetic branch with the genetic similarity coefficient ranging from 0.78 to 0.99. The average indexes of Nei's genetic diversity and Shannon indices were 0.1811 and 0.2750, respectively. This indicated that genetic diversity of FOM was abundant, and the classification of phylogenetic group was related to geographic origin to some extent.

Vegetative Propagule Pressure and Water Depth Affect Biomass and Evenness of Submerged Macrophyte Communities.

Vegetative propagule pressure may affect the establishment and structure of aquatic plant communities that are commonly dominated by plants capable of clonal growth. We experimentally constructed aquatic communities consisting of four submerged macrophytes (Hydrilla verticillata, Ceratophyllum demersum, Elodea nuttallii and Myriophyllum spicatum) with three levels of vegetative propagule pressure (4, 8 and 16 shoot fragments for communities in each pot) and two levels of water depth (30 cm and 70 cm). Increasing vegetative propagule pressure and decreasing water level significantly increased the growth of the submerged macrophyte communities, suggesting that propagule pressure and water depth should be considered when utilizing vegetative propagules to re-establish submerged macrophyte communities in degraded aquatic ecosystems. However, increasing vegetative propagule pressure and decreasing water level significantly decreased evenness of the submerged macrophyte communities because they markedly increased the dominance of H. verticillata and E. nuttallii, but had little impact on that of C. demersum and M. spicatum. Thus, effects of vegetative propagule pressure and water depth are species-specific and increasing vegetative propagule pressure under lower water level can facilitate the establishment success of submerged macrophyte communities.

Sediment type affects competition between a native and an exotic species in coastal China.

Different types of sediments in salt marsh have different physical and chemical characters. Thus sediment type plays a role in plant competition and growth in salt marsh ecosystems. Spartina anglica populations have been increasingly confined to upper elevation gradients of clay, and the niche sediment has changed. Because the niches of S. anglica and the native species Scirpus triqueter overlap, we conducted a greenhouse experiment to test the hypothesis that plant competition has changed under different types of sediments. Biomass and asexual reproduction were analyzed, and inter- and intraspecific competition was measured by log response ratio for the two species in both monoculture and combination under three sediment types (sand, clay and mixture of sand and clay). For S. anglica, biomass, ramet number and rhizome length in combination declined significantly compared with those in monoculture, and the intensity of interspecific competition was significantly higher than that of intraspecific competition under all sediments. For S. triqueter, the intensities of intra- and interspecific competition were not significantly different. This indicates that S. triqueter exerts an asymmetric competitive advantage over S. anglica across all sediments, but especially clay. Thus the sediment type changes competition between S. anglica and S. triqueter.

[The role of transforming growth factor beta1 R II and interleukin 13 Ralpha2 in schistosomiasis-induced hepatic fibrosis].

Schistosomiasis hepatic fibrosis results from excessive deposition of extracellular matrix components which are produced from the activated hepatic stellate cells in liver. Cytokine network disorder is the essential cause of the development of schistosomiasis liver fibrosis. Transforming growth factor beta1 (TGF-beta1) and interleukin 13 (IL-13) promote fibrosis through hepatic stellate cell membrane-specific receptor. This paper reviews the effects of TGF-beta1 type II (TGF-beta1 R II) receptor and IL-13 receptor alpha2 (IL-13 Ralpha2) on hepatic fibrosis.