Identification using Valanis model for beams with nonlinear bolted joint and boundary connection

Bolted joints are widely applied in assembled mechanical structures. This paper focuses on the nonlinear modeling and parameter identification of bolted beams. Two Valanis models are respectively used to describe the nonlinear behaviors of the bolted joint and the boundary connection. Experimental tests at low and high excitation levels are performed to reveal the dynamic characteristics of the bolted beams. The Young’s modulus of the beams is identified via experimental test with low excitation level; whereas the parameters of Valanis model are identified by using optimization technique in order to minimize the residual error between the measured and the simulation data at a high excitation level

Production and purification of the phosphoprotein of Nipah virus in Escherichia coli for use in diagnostic assays.

ABSTRACT Nipah Virus (NiV) is an emerging zoonotic paramyxovirus that can be fatal in humans and various types of animals. The phospho (P) protein of NiV plays an important role in RNA synthesis, replication, and genome synthesis. In this study, the NiV P gene was cloned into a pTrcHis2-TOPO vector and the recombinant protein containing a His-tag was produced in Escherichia coli. SDS-PAGE and Western blot analysis using the anti-His antibody confirmed the protein expression. An optimization study of E. coli fermentation showed that the optimal cultivation temperature was 37°C, while the optimal induction time for P protein expression was at 9 h with 1 mM IPTG. Solubility analysis showed that E. coli cultivated at 37°C produced the highest fraction (70%) of soluble P protein. The recombinant P protein was purified from clarified E. coli lysate using an immobilized metal affinity chromatography (IMAC) technique to a purity of 92.67%, with a purification factor of 11.58. The purified P protein strongly reacted with the anti-NiV swine sera collected during a NiV outbreak, suggesting its potential as a diagnostic reagent

Population genomic analysis of base composition evolution in Drosophila melanogaster.

The relative importance of mutation, selection, and biased gene conversion to patterns of base composition variation in Drosophila melanogaster, and to a lesser extent, D. simulans, has been investigated for many years. However, genomic data from sufficiently large samples to thoroughly characterize patterns of base composition polymorphism within species have been lacking. Here, we report a genome-wide analysis of coding and noncoding polymorphism in a large sample of inbred D. melanogaster strains from Raleigh, North Carolina. Consistent with previous results, we observed that AT mutations fix more frequently than GC mutations in D. melanogaster. Contrary to predictions of previous models of codon usage in D. melanogaster, we found that synonymous sites segregating for derived AT polymorphisms were less skewed toward low frequencies compared with sites segregating a derived GC polymorphism. However, no such pattern was observed for comparable base composition polymorphisms in noncoding DNA. These results suggest that AT-ending codons could currently be favored by natural selection in the D. melanogaster lineage

Fluorescent quantitation method for differentiating the nativity of green fluorescent protein

A gel imaging method was employed to quantitate the GFP that had been subjected to denaturation and degradation treatments. This method is able to differentiate the nativity of GFP by relating the observed changes in the position of fluorescent bands which is unable to be detected using the spectrofluorometric method