Charm Antiquark and Charm Quark in the Nucleon

We estimate the intrinsic charm contributions to the quark flavor and spin observables of the nucleon in the SU(4) quark meson fluctuation model. In this model, the charm or anticharm reside in the charmed mesons created by the nonperturbative quantum quark-meson fluctuations. The intrinsic charm content in the proton, $2\bar c/\sum(q+\bar q) \simeq 0.011\pm 0.008$, is almost one order of magnitude smaller than the intrinsic strange content. The intrinsic charm helicity is also small and negative, $\Delta c\simeq -(0.009\pm 0.006)$. The fraction of the total quark helicity carried by the charm is $|\Delta c/\Delta \Sigma|\simeq 0.021\pm 0.014$. The ratio of the charm with positive helicity to that with negative helicity is c_\up/c_\dw=35/67. For the intrinsic strange component, one has s_\up/s_\dw\simeq 7/13. A detail comparison of our predictions with data and other models or analyses is given. The intrinsic charm contribution to the Ellis-Jaffe sum rule is also discussed.Comment: Revised version, 5 new references, new discussion on $\eta'$ effect...etc. (revtex, 11 pages, 2 figures

Intrinsic Charm Flavor and Helicity Content in the Proton

Contributions to the quark flavor and spin observables from the intrinsic charm in the proton are discussed in the SU(4) quark meson fluctuation model. Our results suggest that the probability of finding the intrinsic charm in the proton is less than 1%. The intrinsic charm helicity is small and negative, $\Delta c \simeq -(0.003\sim 0.015)$. The fraction of the total quark helicity carried by the intrinsic charm is less than 2%, and c_\up/c_\dw=35/67.Comment: 4 pages, 2 tables (revised version

Identification two novel nacrein-like proteins involved in the shell formation of the Pacific oyster Crassostrea gigas

Nacrein-like proteins have carbonic anhydrase (CA)-like domains, but their coding regions are flanked by inserted repeat sequence, such as Gly-X-Asn. Reportedly, nacrein-like proteins show the highest similarity to human carbonic anhydrase 1(α-CA1), possess CA catalytic functions, and play a key role in shell biomineralization. In the present study, two novel nacrein-like proteins were firstly identified from the shell-forming mantle of the Pacific oyster Crassostrea gigas. With numerous analyses, it was identified and characterized that both the nacrein-like proteins F1 and F2 were secreted and most closely related to the nacrein-like protein of California mussel Mytilus californianus via phylogenetic analysis. RT-PCR analysis showed that the nacrein-like proteins F1 and F2 were expressed in multiple tissues and the expression levels remarkably rose after entering the spat stage, which were basically consistent with the increase of calcite fractions in the total shell volume. Surprisingly, the Gly-X-Asn repeat domain, which is distinctive in most nacrein-like proteins, was absent in the two newly identified nacrein-like proteins in C. gigas and replaced with a series of acidic amino acids (D/E). Regardless, nacrein-like proteins in mollusks seem to be vital to the deposition of calcium carbonate and likely perform diverse functions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11033-014-3298-z) contains supplementary material, which is available to authorized users

Evaluation of the DNDC Model to Estimate Soil Parameters, Crop Yield and Nitrous Oxide Emissions for Alternative Long-Term Multi-Cropping Systems in the North China Plain

Funding Information: Funding: National Natural Science Foundation of China (41830751), Hainan University Startup Fund (KYQD(ZR)-20098), the N Circle–a BBSRC-Newton Funded project (BB/N013484/1) and EU Horizon 2020 Programme (Super-G). We thank Bing Gao for providing measurement datasets and Xinping Chen for managing the field trial.Peer reviewedPublisher PD