Determination of Local Strain Distribution at the Level of the Constituents of Particle Reinforced Composite: An Experimental and Numerical Study

This paper is devoted to numerical and experimental investigation of the strain field at the level of the constituents of two-phase particle reinforced composite. The research aims to compare the strain distributions obtained experimentally with the results obtained by using a computational model based on the concept of the representative volume element. A digital image correlation method has been used for experimental determination of full-field strain. The numerical investigation was conducted by the finite element analysis of the representative volume element. Moreover, usage of the novel method of assessment of the speckle pattern applicability for the measurement of local fields by using the digital image correlation method has been proposed. In general, the obtained experimental and numerical results are in good agreement although some discrepancies between the results have been noticed and discussed.

Graphene-Based Materials as Strain Sensors in Glass Fiber/Epoxy Model Composites

The ability of graphene-based materials to act as strain sensors in glass fiber/epoxy model composites by using Raman spectroscopy has been investigated. The strain reporting performance of two types of graphene nanoplatelets (GNPs) was compared with that of graphene produced by chemical vapor deposition (CVD). The strain sensitivity of the thicker GNPs was impeded by their limited aspect ratio and weak interaction between flakes and fibers. The discontinuity of the GNP coating and inconsistency in properties among individual platelets led to scatter in the reported strains. In comparison, continuous and homogeneous CVD grown graphene was more accurate as a strain sensor and suitable for point-by-point strain reporting. The Raman mapping results of CVD graphene and its behavior under cyclic deformation show reversible and reliable strain sensing at low strain levels (up to 0.6% matrix strain), above which interfacial sliding of the CVD graphene layer was observed through an in situ Raman spectroscopic study.

Raman-based microarray readout: a review

For a quarter of a century, microarrays have been part of the routine analytical toolbox. Label-based fluorescence detection is still the commonest optical readout strategy. Since the 1990s, a continuously increasing number of label-based as well as label-free experiments on Raman-based microarray readout concepts have been reported. This review summarizes the possible concepts and methods and their advantages and challenges. A common label-based strategy is based on the binding of selective receptors as well as Raman reporter molecules to plasmonic nanoparticles in a sandwich immunoassay, which results in surface-enhanced Raman scattering signals of the reporter molecule. Alternatively, capture of the analytes can be performed by receptors on a microarray surface. Addition of plasmonic nanoparticles again leads to a surface-enhanced Raman scattering signal, not of a label but directly of the analyte. This approach is mostly proposed for bacteria and cell detection. However, although many promising readout strategies have been discussed in numerous publications, rarely have any of them made the step from proof of concept to a practical application, let alone routine use. Graphical Abstract Possible realization of a SERS (Surface-Enhanced Raman Scattering) system for microarray readout.

Dental materials citations: Part A, January to June 1997

OBJECTIVE

A search was conducted in biomedical journals published from January 1997 to June 1997 to identify all dental materials publications and sort them into major categories.

METHODS

Tables of contents for 79 journals for the period of January to June, 1997 were inspected and divided into 17 categories. Citations were analyzed by both frequency in journals and in categories, as well as compared to frequencies for previous years.

RESULTS

A total of 445 citations were detected in 79 journals for the period January 1997 to June 1997. Certain journals (n = 19) demonstrated a higher citation frequency (> or = 10 citations for 6 months) and represented 77.8% of all citations. The greatest number of citations continued to involve bonding (n = 97), resin-based restorative materials (composites; glass ionomers) (n = 95), prosthodontic materials (n = 51), and pulp protection/luting materials (n = 48). Frequencies by category were very similar to those for the last four years.

SIGNIFICANCE

The compiled literature citations provide a supplement for researchers and academicians seeking information in existing electronic databases.