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The hydrogen/carbon mono-oxide reduction method, based on the difference in thermodynamic stability of yttrium oxide, barium oxide and copper oxide, has been used to determine the oxygen non-stoichiometric fraction, the δ value, in single-phase superconducting YBa2Cu3O6.5+δ . The δ value was found to +0.27 for samples produced by directed reaction process under the given conditions. The present authors regard YBa2Cu3O6.77 as a copper-deficient non-stoichiometric compound.

A directed reaction process based on physico-chemical principles has been designed for producing single-phase 90 K “zero-resistance” superconducting compound YBa2Cu3O6.5+δ. The reliability of the process has been well proved by the stability and reproducibility of results in resistance and AC magnetic susceptibility measurements of seven samples taken randomly from three batches of products. X-ray diffraction, SEM and TEM examinations have identified the product as single-phase polycrystalline material of orthorhombic structure with lattice parameters a=3.89 Å, b=3.82 Å and c=11.65 Å. Many micro-twinned defects were observed under TEM along [110] axes. The nonstoichiometric fraction, δ value, was determined using a physico-chemical method.

Fibrinogen-related proteins (FREPs) are lectins with at least a fibrinogen-like domain. They are widespread in Mollusca and play an important role as immune pattern-recognition receptors. These diverse molecules provide interesting models for the study of the evolution of innate immunity. Although oysters are among the most studied mollusks, there have been few investigations of this gene family in oysters. This paper reports the cloning of the first oyster FREP, named CgFREP, from the Pacific oyster Crassostrea gigas. Five types of FREP (CgFREP-1 to CgFREP-5) were obtained based on a single pair of primers, confirming their high diversity. The proteins deduced from these FREPs contained 253–363 amino acids and were divided into three subfamilies based on sequence identities (cutoff point

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.

In China, the total reserves of vanadium, reported as V2O5, in stone coal is 118 Mt (130 million st). Recovering vanadium from such a large resource is very important to China’s vanadium industry. The technology now being used to recover vanadium from stone coal has the following two problems in the leaching process: a low recovery of vanadium and high acid consumption. To resolve these problems, a new leaching technology is proposed. The effects of factors such as H2SO4 concentration, liquid-solid ratio, temperature and time, and the types and additions of additives were studied. By adding 1.5% (by weight) CaF2 and leaching the roasted residue of stone coal with 5.4% (by weight) sulfuric acid at 90°C for 12 hours at a liquid-solid ratio of 2 mL/g, the leaching degree of vanadium reached 83.10%. This proposed leaching technology gives a feasible alternative for the processing of roasting residue of stone coal and can be applied in the comprehensive utilization of stone coal ores in China.

Heterosis between two stocks (A and B) of the bay scallop Argopecten irradians irradians (Lamarck, 1819) was studied by comparing performance in hatching success, larval survival, larval, spat and adult growth of reciprocal hybrid crosses (AB and BA) and that of two parental groups (AA and BB). Stock A is derived from the initial 1982 introduction from Connecticut, USA and expected to be highly inbred because of the small founder population (26 individuals) and the long breeding history (20 + generations). Stock B is the fourth generation from a 1999 introduction from Virginia and Massachusetts, USA, which is expected to have higher heterozygosity caused by a larger founder population (200 wild and 206 first generation cultured individuals) and a short breeding history. Both hybrid crosses demonstrated positive heterosis for all traits studied, although the magnitude of heterosis varied among traits and life history stages. Midparent heterosis was 7.9% for hatching success, 10.8% and 3.0% for lar...

Duplications and rearrangements of coding genes are major themes in the evolution of mitochondrial genomes, bearing important consequences in the function of mitochondria and the fitness of organisms. Yu et al. (BMC Genomics 2008, 9:477) reported the complete mt genome sequence of the oyster Crassostrea hongkongensis (16,475 bp) and found that a DNA segment containing four tRNA genes (trnK 1 , trnC, trnQ 1 and trnN), a duplicated (rrnS) and a split rRNA gene (rrnL5') was absent compared with that of two other Crassostrea species. It was suggested that the absence was a novel case of "tandem duplication-random loss" with evolutionary significance. We independently sequenced the complete mt genome of three C. hongkongensis individuals, all of which were 18,622 bp and contained the segment that was missing in Yu et al.'s sequence. Further, we designed primers, verified sequences and demonstrated that the sequence loss in Yu et al.'s study was an artifact caused by placing primers in a duplicated region. The duplication and split of ribosomal RNA genes are unique for Crassostrea oysters and not lost in C. hongkongensis. Our study highlights the need for caution when amplifying and sequencing through duplicated regions of the genome.