• 분석과학
• /
• 제17권4호
• /
• pp.315-321
• /
• 2004

The aim of this study was to investigate the evidential value of blue and black ballpoint pens on paper by nondestructive techniques. In this work, 21 blue and 22 black ballpoint pens which were purchased on different brands were analyzed by Raman Spectroscopy and Video Spectral Comparator (VSC). Surface-Enhanced Resonance Raman Spectroscopy (SERRS) with excitation at 685 nm and VSC with several spot light filters were used for the discrimination of ballpoint pen inks. In the SERR spectra, the ballpoint pen inks on paper could be shown sharp spectral bands and distinguished by their band shapes and relative intensities. In the blue and black ballpoint pen inks, the discriminating powers (DP) by SERRS were 0.85 and 0.67 and the DP by VSC were 0.88 and 0.90, respectively. The DP by combined sequence of techniques was all 0.97 in both black and blue ballpoint pen inks.

• 분석과학
• /
• 제18권6호
• /
• pp.460-468
• /
• 2005

The biotin-avidin complex, as a model recognition system, has been constructed through N-hydroxysuccinimide(NHS) reaction on a variety of substrates such as a smooth Au film, electrochemically roughened Au electrode and chemically modified mica. Stepwise self-assembled monolayers (SAMs) of biotin-avidin system were characterized by surface-enhanced resonance Raman scattering (SERRS) spectroscopy, atomic force microscopy (AFM) and surface plasmon resonance (SPR). A strong SERRS signal of rhodamine tags labeled in avidin from the SAMs on a roughened gold electrode indicated the successful complex formation of stepwise biotin-avidin recognition system. AFM images showed the circular shaped avidin aggregates (hexamer) with ca. $60{\AA}$ thick on the substrate, corresponding to one layer of avidin. The surface coverage and concentration of avidin molecules were estimated to be 90% and $7.5{\times}10^{-12}mol/cm^2$, respectively. SPR technique allowed one to monitor the surface reaction of the specific recognition with high sensitivity and precision.

• BMB Reports
• /
• 제42권4호
• /
• pp.223-226
• /
• 2009

We measured the pH-induced spectral changes of yeast iso-1-cytochrome c on silver nanoparticle surfaces using surface-enhanced resonance Raman scattering (SERRS) at 457.9 nm. At a pH of ~3, the Met80 ligand in yeast iso-1-cytochrome c is assumed to dissociate, leading to a marked conformational change as evidenced by the vibrational spectral shifts. The Soret band at ~410 nm in the UV-Vis spectrum shifted to ~396 nm at pH~3, indicating a transition from a low spin state to a high spin state from a weak interaction with a water molecule. Thus, SERRS spectroscopy can measure the pH-induced denaturalization of cyt c adsorbed on metal nanoparticle surfaces at a lower concentration with a better sensitivity than ordinary resonance Raman spectroscopy.

• 분석과학
• /
• 제8권4호
• /
• pp.699-705
• /
• 1995

Monolayers of hypericin, a photodynamic polycyclic quinoidal compound, were prepared at the air-water interface, and were transferred to metal substrates to form Langmuir-Blodgett (LB) monolayers. The structural characteristics of hypericin LB monolayers and self-assembled (SA) monolayers were investigated using surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Both the spectroscopic data and the surface pressure - area (${\pi}-A$) isotherms suggest that hypericin forms ${\pi}-{\pi}$ aggregates that orient vertically to the subphase surface. Whereas the ordering and orientation of control was less effective in SA monolayers, a higher structural regularity was attained in LB systems. The effect of subphase on the structural integrity of the monolayer was also investigated.

• Structural Engineering and Mechanics
• /
• 제74권6호
• /
• pp.723-735
• /
• 2020

This study is reported the adhesion failure in adhesive bonded composite and specifically for the T-joint structure. Three-dimensional finite element analysis has been performed using a commercial tool and the necessary outcomes are obtained via an eight noded solid element (Solid 185-element) from the library of ANSYS. The structural analysis input has been incurred through ANSYS parametric design language (APDL) code. The normal and shear stress distributions along different layers of the joint structure have been evaluated as the final outcomes. Based on the stress distributions, failure location in the composite joint structure has been identified by using the Tsai-Wu stress failure criterion. It has been found that the failure index is maximum at the interface between flange and web part of the joint (top layer) which indicates the probable location of failure initiation. This kind of failures are considered as adhesion failure and the failure propagation is governed by strain energy release rate (SERR) of fracture mechanics. The different adhesion failure lengths are also considered at the failure location to calculate the SERR values i.e. mode I fracture (opening), mode II fracture (sliding) and mode III fracture (tearing) along the failure front. Also, virtual crack closure technique (VCCT) principle of fracture mechanics steps is used to calculate the above said SERRs. It is found that the mode I SERR is more dominating compared to other two modes of failure for the joint considered. Finally, the influences of various parametric (geometrical and material) effect on SERR of the joint structure are evaluated and discussed in details.