Imaging Surface Displacements of Piezoelectric Composites

Studies over the last ten years have shown that composite piezoelectrics can have a significant advantage over monolithic materials for a number of applications, especially in transducers used in medical imaging. In conventional ceramics the Poisson effect lowers the thickness mode displacement that can occur in wide specimens at high frequencies. This effect is sometimes referred to as self pinning. In one specific type of composite (type 1–3) the proper incorporation of an array of rods made from a piezoelectric ceramic such as PZT in an inactive matrix such as epoxy will form a composite piezoelectric with much lower self pinning than occurs in a monolithic ceramic. For medical applications composite transducer materials may consist of rods as small as 100 microns across and separated by about 25 microns. For lower frequency applications, the rods may be as large as 1.0 mm and be separated by 4.0 mm or more. Characteristics of piezoelectric composite materials and the conventions used in naming them are described in a review article by Smith [1]

Evaluation of fiber-reinforced composites using noncontact laser air- transducer system

Ultrasonic evaluation of materials using a non-contact system is sometimes desirable, for example when the material is moving too quickly to allow conventional fluid couplants to be used, is contained in a hostile environment, or the material itself is absorbent or toxic. In such situations, a pulsed laser is ideal for generating a variety of ultrasonic transients [1], as longitudinal, shear, surface (Rayleigh) waves and plate (Lamb) waves are generated simultaneously. Several types of non-contact detector are also available, including various optical devices [2] such as interferometers and beam deflectors. The disadvantages of an entirely laser based system are cost, and the optical quality of the test material must be reasonably high

Split-intein mediated circular ligation used in the synthesis of cyclic peptide libraries in E-coli

Recent advances in chemical biology and the advantages presented by in vivo screening have highlighted the need for a robust and flexible biologically synthesized small-molecule library. Herein we describe a method for the biosynthesis of cyclic peptide libraries of up to 108 members in Escherichia coli using split-intein circular ligation of peptides and proteins (SICLOPPS). The method utilizes split-intein chemistry to cyclize randomized peptide sequences. The cyclic peptide library can potentially be of any size and the peptide itself may contain unlimited random residues. However, the library size is limited by the transformation efficiency of E. coli and random residues are generally limited to five, but additional amino acids can be used in the cyclic peptide backbone, varying the structure and ring size of the cyclic peptide. SICLOPPS libraries have been combined with a bacterial reverse two-hybrid system in our labs and used in the identification of inhibitors of several protein–protein interactions. This protocol is expected to take around 3–4 weeks to implement.<br/