Orientation Relationship of the Intergrowth Al₁₃Fe₃ and Al₁₃Fe₄ Intermetallics Determined by Single-Crystal X-ray Diffraction

In the Al-Fe binary system, the Al13Fe3 phase as well as the Al13Fe4 phase has similar icosahedral building blocks like those appearing in quasicrystals. Therefore, it is of vital importance to clarify the formation process of these two phases. Coexistence of the Al13Fe3 and Al13Fe4 phases was discovered from the educts obtained with a nominal atomic ratio of Al/Fe of 9:2 by high-pressure sintering for the first time. Firstly, single crystal X-ray diffraction (SXRD) combined with a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) measurement capabilities were adopted to determine the detailed crystal structures of both phases, which were sharply refined with regard to Al13Fe3 and Al13Fe4. Secondly, the orientation relationship between Al13Fe3 and Al13Fe4 was directly deduced from the SXRD datasets and the coexistence structure model was consequently constructed. Finally, seven pairs of parallel atomic planes and their unique orientation relations were determined from the reconstructed reciprocal space precession images. In addition, the real space structure model of the intergrowth crystal along with one kind of interfacial atomic structure were constructed from the determined orientation relations between two phases

Periodic Mechanical Stress Stimulates the FAK Mitogenic Signal in Rat Chondrocytes Through ERK1/2 Activity

Background/Aims: The biological effects of periodic mechanical stress on chondrocytes have been studied extensively over the past few years. However, the mechanisms underlying chondrocyte mechanosensing and signaling in response to periodic mechanical stress remain to be determined. In the current study, we examined the effects of focal adhesion kinase (FAK) signaling on periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. Methods and Results: Periodic mechanical stress significantly induced sustained phosphorylation of FAK at Tyr397 and Tyr576/577. Reduction of FAK with targeted shRNA via transfection of NH2-terminal tyrosine phosphorylation-deficient FAK mutant Y397F or Y576F-Y577F abolished periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis, accompanied by attenuated ERK1/2 phosphorylation. However, activation of Src, PLCγ1 and Rac1 was not prevented upon FAK suppression. Furthermore, pretreatment with the Src-selective inhibitor, PP2, and shRNA targeted to Src or suppression of Rac1 with its selective inhibitor, NSC23766, blocked FAK phosphorylation at Tyr,576/577 but not Tyr,397 under periodic mechanical stress. Interestingly, FAK phosphorylation neither at Tyr397 nor at Tyr576/577 was affected by PLCγ1 depletion when periodic mechanical stress was applied. In addition, Tyr397 and Tyr576/577 phosphorylation levels were reduced upon pretreatment with a blocking antibody against integrin β1 under conditions of periodic mechanical stress. Conclusion: Our findings collectively suggest that periodic mechanical stress promotes chondrocyte proliferation and matrix synthesis through at least two pathways, integrin β1-Src-Rac1-FAK(Tyr576/577)-ERK1/2 and integrin β1-FAK (Tyr397)-ERK1/2

Inhibition of Chitosan with Different Molecular Weights on Barley-Borne Fusarium graminearum during Barley Malting Process for Improving Malt Quality

There are many Fusarium graminearum contaminations in barley that are often associated with malt and beer quality issues. Thus, it is important to find a biological antifungal agent to prevent the growth of F. graminearum during malting. Minimum inhibition concentration (MIC) of chitosan for mycelial growth and spore germination of F. graminearum was 2.6 g/L and 1.6 g/L, respectively, indicating that the F. graminearum strain was highly sensitive toward chitosan. Chitosan with a molecular weight of 102.7 kDa was added at 0.5 g/kg during the first steeping stage, resulting in the maximum inhibition rate of F. graminearm in barley. The biomass of F. graminearm and deoxynivalenol content in the infected barley at the end of germination with 0.5 g/kg chitosan treatment were decreased by 50.7% and 70.5%, respectively, when compared with the infected barley without chitosan. Chitosan could remove the negative effects of F. graminearm infection on barley germination and malt quality, which makes the application of chitosan during the steeping process as a potential antifungal agent in the malting process to protect from F. graminearum infection

Application of EPMA and LA-ICP-MS to Study Mineralogy of Arsenopyrite from the Haoyaoerhudong Gold Deposit, Inner Mongolia, China

BACKGROUND: The composition of major and trace elements in arsenopyrite can be used to identify the occurrence of elements and explore the remobilization and migration behaviour of elements in different stages. The Haoyaoerhudong gold deposit in Inner Mongolia is a super large gold deposit hosted in the black shales of the Bayan Obo Group. Gold-bearing minerals such as arsenopyrite and loellingite are present. Previous researchers have used the traditional powder dissolution method to analyze the isotope of the ore and discussed the source of ore-forming materials, but the migration and enrichment mechanism of gold has not been unraveled.OBJECTIVES: To understand the gold migration and enrichment process of this deposit.METHODS: Based on mineralogy, different types of arsenopyrite were analyzed by electron probe microanalyzer (EPMA) and inductively coupled plasma-mass spectrometry (ICP-MS). The data measured by EPMA was corrected by ZAF program, and the data measured by LA-ICP-MS was quantitatively calculated by "no internal standard-matrix normalized calibration".RESULTS: The results showed that loellingite was developed in arsenopyrite. They can be divided into Apy-Ⅰ1, Apy-Ⅰ2, Lo-Ⅰ in progressive shear deformation stage and Apy-Ⅱ1, Apy-Ⅱ2 and Lo-Ⅱ in post shear deformation stage. The major element composition of arsenopyrite in different generations was stable, with a small amount of Co and Ni and a trace amount of Sb, Te, Bi, Pb, Au and Ag. Cobalt was higher in Apy-Ⅱ1 and Apy-Ⅱ2, whereas Au, Bi, Pb and Te were obviously enriched in Apy-Ⅰ1. Loellingite was rich in As (64.06%-67.87%), Co (0.33%-4.98%), Ni (1.23%-6.37%). Trace elements such as Au, Te, Bi, Pb and Ag were more enriched in Lo-Ⅱ.CONCLUSIONS: Lo-Ⅱ is the most important gold-bearing mineral. The changes of temperature and sulfur fugacity lead to the precipitation of loellingite and native gold. Native gold is precipitated by remobilization and migration of "invisible gold" in early arsenopyrite and loellingite

3D profile micrographs from the center of the wear zone of the femoral head (a) and cup (c) in control group after 3MC wear test.

<p>More protein deposition, shallow grooves, less wear. 3D profile micrographs from the wear zone of the femoral head (b) and cup (d) in experimental group after 3MC wear test. Less protein deposition, deeper grooves, more wear.</p

Demographics of the cumulative volumetric wear of cups and heads.

<p>Demographics of the cumulative volumetric wear of cups and heads.</p

Integrin β1 Gene Therapy Enhances in Vitro Creation of Tissue-Engineered Cartilage Under Periodic Mechanical Stress

Background/Aims: Periodic mechanical stress activates integrin β1-initiated signal pathways to promote chondrocyte proliferation and matrix synthesis. Integrin β1 overexpression has been demonstrated to play important roles in improving the activities and functions of several non-chondrocytic cell types. Therefore, in the current study, we evaluated the effects of integrin β1 up-regulation on periodic mechanical stress-induced chondrocyte proliferation, matrix synthesis and ERK1/2 phosphorylation in chondrocyte monolayer culture, and evaluated the quality of tissue-engineered cartilage constructed in vitro under periodic mechanical stress combined with integrin β1 up-regulation. Methods and Results: Our results revealed that under periodic mechanical stress, pre-treatment with integrin β1-wild type vector significantly enhanced chondrocyte proliferation and matrix synthesis and promoted ERK1/2 phosphorylation in comparison to mock transfectants. Furthermore, when chondrocytes were seeded in PLGA scaffolds, more accumulated GAG and type II collagen tissue were detected after Lv-integrin β1 transfection compared with sham controls exposed to periodic mechanical stress. In contrast, in the Lv-shRNA-integrin β1 group, the opposite results were observed. Conclusion: Our findings collectively suggest that in addition to periodic mechanical stress, integrin β1 up-regulation in chondrocytes could further improve the quality of tissue-engineered cartilage