Studies on the Microstructural Evolution and Mechanical Properties of Superalloy Inconel 718 Induced by Low Plasticity Burnishing Coupled with Turning.

Mechanical surface treatments are needed to perform on components for fatigue life enhancement by introducing beneficial compressive residual stress and material strengthening. In this study, the combined turning with low plasticity burnishing (LPB) surface modification process was performed for the sake of improving mechanical properties of Inconel 718. Firstly, the evolution of microstructure and residual stress after the LPB process were analyzed with the aid of electron backscatter diffraction (EBSD) and X-ray diffraction (XRD), respectively. Secondly, the tensile behavior of treated samples was investigated through tension tests. Finally, the micro-strengthening mechanism of Inconel 718, induced by the LPB process, was revealed. The results show that the peak compressive stress is increased by a factor of 4.2 after the LPB process. The grain refinement induced by the LPB process is attributed to the increase of average misorientation and the formation of high angle grain boundaries (HAGBs). The enhanced yield strength depends on the decreased average spacing and the increased HAGBs.

A fluorescence detection scheme for ultra large molecules after gas phase separation.

A system was proposed to remove the upper mass limitation of mass spectrometry. In present study, ultra large molecules were separated in the gas phase by mass analyzer after electrospray ionization. Instead of conventional detection with electron multiplier, a laser-induced-fluorescence detection scheme was applied. The instrument sensitivity is independent of molecular weight, but related to the spectroscopic properties of the fluorophores presented by the large biomolecules.

Multiplexed flow cytometric immunoassay for influenza virus detection and differentiation.

Microsphere-based immunoassay by flow cytometry has gained popularity lately in protein detection and infectious disease diagnosis due to its capacity for multiplexed analysis and simple assay format. Here, we demonstrated the power of microsphere-based immunoassay for high-sensitivity detection and accurate differentiation of influenza viruses. The effects of sample volume and bead number on the assay sensitivity of viral antigen detection were studied. Compared to enzyme-linked immunosorbent assays, flow-based bead assays provided approximately 10-fold lower detection limit for viral particle detection and performed similarly for recombinant viral hemagglutinin protein detection. A four-plexed assay for influenza virus typing and influenza B virus sublineage characterization was developed to demonstrate the potential for multiplexed viral antigen detection and differentiation.

Binding and cytotoxicity of HPMA copolymer conjugates to lymphocytes mediated by receptor-binding epitopes.

PURPOSE: Studies on the recognition of epitopes presented on a template peptide showed the potential of nonapeptide-related sequences to act as biorecognition sites for the B-cell CD21 receptor. This study was intended to evaluate the capability of three epitope sequences to mediate specific cell binding and to enhance the cytotoxicity of HPMA copolymer conjugates. METHODS: HPMA copolymer conjugates were synthesized containing three different epitopes at various contents and either a fluorescent marker or doxorubicin (DOX). The binding and cytotoxicity of the conjugates to CD21+ Raji B cells and CD21- HSB-2 T cells were evaluated. RESULTS: The epitope-containing conjugates were found to bind to Raji cells at different apparent affinities depending on epitope structure and content. The conjugates generally possessed higher affinities for Raji cells than for HSB-2 cells. Targeted HPMA copolymer-DOX conjugates exhibited higher cytotoxicities than the nontargeted conjugate, likely indicative of enhanced internalization by receptor-mediated endocytosis. HSB-2 cells were more sensitive to both free and polymer-bound DOX than Raji cells; however, the enhancement of cytotoxicity of the conjugates by incorporation of epitopes was more pronounced for Raji cells. CONCLUSIONS: The results verified the concept of using receptor-binding epitopes as targeting moieties in HPMA copolymer conjugates for the delivery of anticancer drugs to lymphoma cells.

Presentation of epitopes on genetically engineered peptides and selection of lymphoma-targeting moieties based on epitope biorecognition.

A His-tagged coiled coil stem loop peptide with stable secondary structure was designed and biosynthesized. A series of oligopeptides related to the EBV envelope glycoprotein 350/220 N-terminal nonapeptide as potential CD21 receptor-binding epitopes were engineered into the loop region of the peptide scaffold. It was shown that these peptides had a stable alpha-helical coiled coil structure and assumed a monomeric form in PBS. Biorecognition of the epitopes was studied by immobilizing the epitope-containing peptides on complexed Ni2+-containing surfaces through His-Ni2+ chelation and incubating with purified soluble CD21 receptor or CD21+ cells. The results showed that the potential epitopes bound to CD21 and CD21+ cells at different affinities depending on oligopeptide structures. This approach allows for the evaluation of epitope biorecognizabilities and the selection of optimal oligopeptides among sequences for use as targeting moieties in the design of new lymphoma-targeting polymeric drug carriers.