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Dermatophagoides farinae, a domestic mite species, produces some of the most potent allergens that contribute to allergy in China and worldwide. We sought to clone and express the group 8 allergen of D. farinae (Der f 8) to investigate its IgE-binding reactivity. The full-length cDNA encoding Der f 8 was generated by using RT-PCR and 5' RACE, cloned into pCold-TF expression vector, confirmed by nucleotide sequencing, sub-cloned into pET-28b (+), and transfected into E. coli BL21 cells for expression. After purification by nickel affinity chromatography and identified by SDS-PAGE, the recombinant Der f 8 bound with sera from 40.9 % (9/22) of mite-allergic patients according to ELISA testing. Analysis of the recombinant DNA sequence revealed a 231 amino acid open reading frame encoding a protein with a derived molecular mass of 26.4 kDa and an isoelectric point of 6.84. The deduced amino acid sequence has nine phosphorylation sites, displaying strong homology with glutathione S-transferase, and its secondary structure comprises alpha helix (45.5 %), extended strand (11.3 %), and random coils (43.3 %). BLAST through the National Center for Biotechnology Information database and alignment identified similarity with group 8 allergens or glutathione S-transferases of Dermatophagoides pteronyssinus, Suidasia medanensis, Lepidoglyphus destructor, Glycyphagus domesticus, and Aleuroglyphus ovatus (64, 65, 53, 53, and 50 %, respectively). The first recombinant Der f 8 protein produced in full length successfully bound with patient IgE, demonstrating the importance of Der f 8 in mite allergy.

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Effects of Cr, Al and Hf, varied from 0 -32 wt.%, 1 -7.5 wt.% and 0.3 -1.5 wt.% respectively, on reactions between nickel base alloy melt and silicon oxide core were investigated in this paper. Role of temperature also was studied. Morphology and structures of reaction products were analyzed by scanning electron microscope (SEM) with the energy dispersive spectrometry (EDS) and the X-ray diffraction (XRD) technique. Amount of alumina in interface increased with Cr level, and formed a layer with thickness up to several microns in alloy of 32 wt.% Cr, and 1 wt.% Al. Reaction products in alloy without Hf were mainly alumina, while in alloy with Hf were mainly hafnium oxides and alumina. More hafnium oxides were formed in alloy with 1.5 wt.%Hf and 9 wt.% Cr, while more alumina formed in alloy with 0.3 wt.%Hf and 15 wt.%Cr, a double layer of reaction products formed at the temperature of 1540 ºC, which were composed of a hafnium oxide layer near the metal and a alumina layer above it. The result shows that Cr, Hf levels in the alloy and reaction temperature have the effect of accelerating interface reaction.