XRD and SEM analysis near the diffusion bonding interface of Mg/Al dissimilar materials

As sessile organisms, plants are unable to avoid being subjected to environmental stresses that negatively affect their growth and productivity Instead, they utilize various mechanisms at the morphological, physiological, and biochemical levels to alleviate the deleterious effects of such stresses Amongst these, secondary metabolites produced by plants represent an important component of the defense system Secondary metabolites, namely phenolics, terpenes, and nitrogen-containing compounds, have been extensively demonstrated to protect plants against multiple stresses, both biotic (herbivores and pathogenic microorganisms) and abiotic (eg drought, salinity, and heavy metals) The regulation of secondary metabolism by beneficial elements such as silicon (Si) is an important topic Silicon-mediated alleviation of both biotic and abiotic stresses has been well documented in numerous plant species Recently, many studies have demonstrated the involvement of Si in strengthening stress tolerance through the modulation of secondary metabolism In this review, we discuss Si-mediated regulation of the synthesis, metabolism, and modification of secondary metabolites that lead to enhanced stress tolerance, with a focus on physiological, biochemical, and molecular aspects Whilst mechanisms involved in Si-mediated regulation of pathogen resistance via secondary metabolism have been established in plants, they are largely unknown in the case of abiotic stresses, thus leaving an important gap in our current knowledge

Integration of silicon and secondary metabolites in plants: a significant association in stress tolerance.

The phase transition behaviors of non-metallic inclusions as a function of Ti content were investigated by monitoring changes in the microstructure and mechanical properties of high-strength low-alloy steel multipass weld metals Weld metals with Ti contents ranging from 0007 to 017 wt% were prepared using a gas metal arc welding process The inclusion analysis was performed based on thermodynamic calculations and transmission electron microscopy, accompanied by energy-dispersive spectrometry and selected area electron diffraction With increase in the Ti content of weld metals, the chaotic arrangement of ferrite laths in the columnar zone was transited to a well aligned arrangement and the impact toughness of the weld metals drastically deteriorated in response to the decrease in the Mn content of the inclusion The effective inclusion phase for intragranular nucleation contained considerable amounts of Mn and a Mn depleted zone was observed around the effective nucleant

Influence of Ti on non-metallic inclusion formation and acicular ferrite nucleation in high-strength low-alloy steel weld metals

Effect of cooling rate on microstructure, inclusions and mechanical properties of weld metal in simulated local dry underwater welding

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Solid-state bonding between Al and Cu by vacuum hot pressing

Ten new p-terphenyl derivatives, floricolins A–J (1–10), together with six known compounds (11–16), were isolated from the extract of the endolichenic fungus Floricola striata. Chemical structures of these compounds were elucidated using spectroscopic data (HRESIMS and NMR). Among them, 9 and 10 were enantiomeric mixtures, and their configurations were established by single-crystal X-ray diffraction analysis using Cu Kα radiation. Evaluation of the isolated compounds against Candida albicans revealed that the most active compound, 3 (MIC 8 μg/mL), exerted fungicidal action by destruction of the cell membrane.

p-Terphenyl Derivatives from the Endolichenic Fungus Floricola striata.

Eleven new p-terphenyls, floricolins K-U (1-11), together with 13 biosynthetically related known compounds (12-24) were isolated from an endolichenic fungus, Floricola striata. Their structures were elucidated by extensive spectroscopic analyses and single-crystal X-ray diffraction measurements. The newly isolated p-terphenyls inhibited the growth of A2780, MCF-7, and A549 cell lines. Further evaluation for the multidrug resistance (MDR) reversal activity of compound 5 revealed it enhanced the sensitivity of MCF-7/ADR cells toward adriamycin 39-fold at 10 μM through modulating P-glycoprotein-mediated drug exclusion.

Cytotoxic p-Terphenyls from the Endolichenic Fungus Floricola striata.

Dissimilar metals of copper (T2) and aluminium (1035) were brazed by vacuum brazing technology. Microstructure and phase constitution for the Cu/Al vacuum brazing were studied by means of metallography, electron probe microanalyser and X-ray diffraction. Experiment results indicated that an obvious transition layer of copper based solution was formed near the interface of copper and braze metal. The brazing seam zone mainly consists of various solid solutions between many elements and a few intermetallic compounds which are hard and brittle. This is favourable to the enhancing of service performance of the Cu/Al brazed joint. Process parameters of vacuum brazing are: brazing temperature T=425°C, vacuum level=10−3 Pa, holding time t=15 min.

Microstructure and phase constitution near interface of Cu/Al vacuum brazing

High strength low alloy steel was welded by gas shielded arc welding process without preheating. Microstructural characteristics of the weld metal, morphology of inclusions and crack propagation paths were investigated by means of optical microscopy and scanning electron microscopy. The chemical composition of the inclusion and element distribution across the inclusion were analysed via energy dispersive spectroscopy system. Results indicated relatively large inclusions with diameters of about 0·6–0·8 μm are much more effective in providing nucleation sites for acicular ferrite transformation and refining the microstructure within austenite grain than small ones with diameters of about 0·3–0·5 μm. When the main crack tip encountered inclusion, more crack paths would be initiated from the interface between inclusion and acicular ferrite plates.

Effects of inclusions on formation of acicular ferrite and propagation of crack in high strength low alloy steel weld metal

The isolation of the cytotoxic fractions from the endolichenic fungus Ophiosphaerella korrae yielded six new metabolites, including five polyketides (ophiofuranones A (1) and B (2), with unusual furopyran-3,4-dione-fused heterocyclic skeletons, ophiochromanone (3), ophiolactone (4), and ophioisocoumarin (5)), one sesquiterpenoid ophiokorrin (10), and nine known compounds. Their structures were established on the basis of the analysis of HRESIMS and NMR spectroscopic data. ECD calculations, GIAO NMR shift calculations and single-crystal X-ray diffraction were employed for the stereo-structure determination. A plausible biogenetic pathway for the ophiofuranones A (1) and B (2) was proposed. The cytotoxic assay suggested that the five known perylenequinones mainly contributed to the cytoxicity of the extract. Further phytotoxic studies indicated that ophiokorrin inhibited root elongation in the germination of Arabidopsis thaliana with an IC50 value of 18.06 μg mL−1.

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Yue-Lan Li

Papers

p-Terphenyl Derivatives from the Endolichenic Fungus Floricola striata.

Cytotoxic p-Terphenyls from the Endolichenic Fungus Floricola striata.

Microstructure and phase constitution near interface of Cu/Al vacuum brazing

Effects of inclusions on formation of acicular ferrite and propagation of crack in high strength low alloy steel weld metal

Secondary metabolites from the endolichenic fungus Ophiosphaerella korrae