Hasil untuk "physics.gen-ph"

R. Bates

M. Wachstein, E. Meisel

D. Brookins

A. Gourine, V. Kasymov, N. Marina et al.

M. Wedborg, D. Turner, L. Anderson et al.

A. Savina, C. Jancic, S. Hugues et al.

Sung-Ching Chen, Yung-Chih Wu, F. Mi et al.

Y. Ohno, K. Maehashi, Y. Yamashiro et al.

R. Cardone, V. Casavola, S. Reshkin

C. Shih, Shangchao Lin, Richa Sharma et al.

J. Xiong, Yongqin Liu, Xiangui Lin et al.

Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4–1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r = 0.443, P = 0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments.

G. Jeppu, T. Clement

A. Bandodkar, V. Hung, W. Jia et al.

Matthew A. McBrian, Iman Saramipoor Behbahan, R. Ferrari et al.

A. Andrés-Bello, V. Barreto-Palacios, P. García-Segovia et al.

N. Revsbech, B. B. Jørgensen, T. Henry Blackburn et al.

D. Longo, P. Sun, Lorena Consolino et al.

Chemical exchange saturation transfer (CEST) is a novel contrast mechanism for magnetic resonance imaging (MRI). CEST MRI selectively saturates exchangeable protons that are transferred to MRI-detectable bulk water signal. MRI-CEST (pH)-responsive agents are probes able to map pH in the microenvironment in which they distribute. To minimize the confounding effects of contrast agent concentration, researchers have developed ratiometric CEST imaging, which investigates contrast agents containing multiple magnetically non-equivalent proton groups, whose prototropic exchange have different pH responses. However, conventional ratiometric CEST MRI imposes stringent requirements on the selection of CEST contrasts agents. In this study, a novel ratiometric pH MRI method based on the analysis of CEST effects under different radio frequency irradiation power levels was developed. The proposed method has been demonstrated using iobitridol, an X-ray contrast agent analog of iopamidol but containing a single set of amide protons, both in vitro and in vivo.

D. Lomiwes, M. Farouk, G. Wu et al.

T. Nishigaki, Omar José, A. L. González-Cota et al.

M. Averyanova, E. Cicala, P. Bertrand et al.