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Summary Elevation in homocysteine (Hcy) level is associated with insulin resistance; however, the causality between them and the underlying mechanism remain elusive. Here, we show that Hcy induces insulin resistance and causes diabetic phenotypes by protein cysteine-homocysteinylation (C-Hcy) of the pro-insulin receptor (pro-IR). Mechanistically, Hcy reacts and modifies cysteine-825 of pro-IR in the endoplasmic reticulum (ER) and abrogates the formation of the original disulfide bond. C-Hcy impairs the interaction between pro-IR and the Furin protease in the Golgi apparatus, thereby hindering the cleavage of pro-IR. In mice, an increase in Hcy level decreases the mature IR level in various tissues, thereby inducing insulin resistance and the type 2 diabetes phenotype. Furthermore, inhibition of C-Hcy in vivo and in vitro by overexpressing protein disulfide isomerase rescues the Hcy-induced phenotypes. In conclusion, C-Hcy in the ER can serve as a potential pharmacological target for developing drugs to prevent insulin resistance and increase insulin sensitivity.

A new surface molecularly imprinted polymer (MIP) based on nano-TiO2 was developed using propazine (Pro) as a template molecule, ethyleneglycol dimethacrylate (EGDMA) as a crosslinker, methacrylic acid (MAA) as a functional monomer, and 2,2'-azobis (isobutyronitrile) (AIBN) as an initiator. Structures of the newly synthesized surface MIPs were characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The MIP had a good adsorption capacity and high recognition selectivity to propazine. Meanwhile, it exhibited a cross-selectivity for simazine (Sim) and atrazine (Atr). The MIPs were used as a solid phase extraction (SPE) material. Concomitant extraction, purification, and determination of three pesticides (Pro, Sim, and Atr) residues in water, soil, and maize plant and grain samples were performed by MIP-SPE coupled with high performance liquid chromatography (HPLC). The highly selective separation and enrichment of Pro, Atr, and Sim from the complex environmental media can be achieved. Thus, the newly developed technique provides an analytical platform to quantify the trace amount of Pro, Sim, and Atr residues in multi environmental media and food source.

The copper based electric contact materials with multicomponent substance were obtained by powder metallurgy. The hardness and density of the samples increase with adding proper amount of Y 2 O 3 . Adding 1.5 wt.% Y 2 O 3 the hardness of the sample reaches the maxim and the density of sample reaches the maximum by adding 2 wt.% Y 2 O 3 . In this paper, the effects of addition of Y 2 O 3 on the performance of copper based contact materials were studied by metallographic microscope, XRD, SEM in details. Moreover, the mechanism of the effects was discussed.

Si3N4/ Al–Mg composites reinforced by ceramic interpenetrating network structure had been fabricated via pressureless infiltration technology. The matrix and the reinforcement phase, form an interconnected interpenetrating network structure. The Al–Mg/Si3N4 system exhibits an excellent wettability under moderate conditions. The increasing of Mg content (2–10 wt%) resulted in an increased amount of infiltration, once Mg content beyond 10 wt% has an adverse effect. Light chemical reaction occurs in the interface of Al–Mg/Si3N4 system and the reaction productions reduce the surface tension of melt and impulse the advance of infiltration. Infiltration temperature and infiltration time were the key parameters, which turn into the infiltration impetus. The appropriate infiltration temperature is 1050 °C and the corresponding infiltration time is 15 min, prolonging the infiltration time continuously has no significance.

A multiphase reticulated porous ceramic (RPC) as Si3N4–Al2O3–SiO2 was fabricated by replication techniques. Proper volumes of additives and twice sinter- twice immerse process endow the RPC an excellent crack healing and submerging property. The compressive strength and fracture toughness improved owing to the crack bridging behavior. The existence of pores in struts in RPC blunt the crack tip and increased the external force needed to propagate the crack. The mechanisms play a beneficial role in enhancing the compressive strength and fracture strength. Si3N4 RPC with additives of 5%Al and 5% Al2O3 yielded the compressive strength of 9.8 MPa and fracture toughness of 0.3 MPa m1/2.

Metal matrix composites reinforced by three-dimensional (3-D) continuous network structure reinforcement (3DCNRMMC) are difficult to machine due to serious tool wear and poor surface roughness caused by the brittle and hard reinforcement which interpenetrate into ductile matrix. In order to achieve the approach of low cost of 3DCNRMMC, the machinability of it needs to be understood. The influences of three cutting parameters and volume fraction of reinforcement on cutting force were analyzed in detail. The results indicate that: (1) Due to the brittle phase(s) introduced into ductile matrix of composites, there is a large fluctuation of cutting force causing deterioration of machinability. The fluctuation ranges of cutting forces, initially increase rapidly with the increase of volume fraction of reinforcement and then decrease finally, are largest at the range of the volume fraction of 55–65%; (2) The influence of cutting parameters on cutting force is obvious. With the increases of cutting speed, cutting force decreases gradually unless cutting speed exceeds the value of 209 m/min. Cutting forces increase with increasing feed rate and depth of cut; (3) Owing to the large fluctuation of cutting force, there were some cratered surfaces caused by Si3N4 reinforcement pulling-out and flaking-off. Some brittle phase protruding from the machined surface caused the deterioration of machined surface.

One kind of three-dimensional network structure, reinforced aluminum magnesium matrix composites, has been prepared by pressure-assisted and vacuum-driven infiltration technology. The composites interpenetrated with ceramic have higher wear resistance than the metal matrix owing to their special topology structure. The reinforcement volume fraction has a large effect on abrasive wear. The wear rate decreases with the increase of the volume fraction of reinforcement and increases with the increase of sliding time and applied load. The wear mechanism of the composites (abrasive wear) differs greatly from the matrix alloy (adhesive wear).