Optimization of sensor design for Barkhausen noise measurement using finite element analysis

The effects of design parameters for optimizing the performance of sensors for magneticBarkhausen emission measurement are presented. This study was performed using finite element analysis. The design parameters investigated include core material, core-tip curvature, core length, and pole spacing. Considering a combination of permeability and saturation magnetization, iron was selected as the core material among other materials investigated. Although a flat core-tip would result in higher magnetic flux concentration in the test specimen, a curved core-tip is preferred. The sensor-to-specimen coupling is thereby improved especially for materials with different surface geometries. Smaller pole spacing resulted in higher flux concentration

An Integrated Multidisciplinary Nanoscience Concentration Certificate Program for STEM Education

Integration of nanoscience and nanotechnology curricula into the College of Science, Mathematics, and Technology (CSMT) at the University of Texas at Brownsville (UTB) is reported. The rationale for the established multidisciplinary Nanoscience Concentration Certificate Program (NCCP) is to: (i) develop nanotechnology-relevant courses within a comprehensive Science, Engineering and Technology curriculum, and, to offer students an opportunity to graduate with a certificate in nanoscience and nanotechnology; (ii) to contribute to students\u27 success in achieving student outcomes across all college\u27s majors, and, improve the breath, depth and quality of science, technology, engineering and mathematics (STEM) graduates\u27 education; (iii) through NCCP, recruit certificate- and associate-degree seeking students into four year programs in engineering and physical sciences. A long-term goal is to develop an ABET accredited bachelor program in nanoscience. This program is expected to reach out to a large group of undergraduate students in a coordinated manner, enhance students\u27 knowledge and skills, as well as facilitate efforts of individual faculty members in STEM education. The UTB NCCP is supported by the NSF NUE program, under which we are developing and offering seven upper-level interdisciplinary undergraduate courses. These courses and program are assessed and evaluated

Forced and self-excited oscillations of an optomechanical cavity

We experimentally study forced and self oscillations of an optomechanical cavity which is formed between a fiber Bragg grating that serves as a static mirror and between a freely suspended metallic mechanical resonator that serves as a moving mirror. In the domain of small amplitude mechanical oscillations, we find that the optomechanical coupling is manifested as changes in the effective resonance frequency, damping rate and cubic nonlinearity of the mechanical resonator. Moreover, self oscillations of the micromechanical mirror are observed above a certain optical power threshold. A comparison between the experimental results and a theoretical model that we have recently presented yields a good agreement. The comparison also indicates that the dominant optomechanical coupling mechanism is the heating of the metallic mirror due to optical absorption.Comment: 11 pages, 6 figure

Reversible Photoisomerization in Thin Surface Films from Azo-Functionalized Guanosine Derivatives

[Image: see text] Two novel azo-functionalized guanosine derivatives were synthesized, and their photoisomerization process was investigated in molecular monolayers at the air–water interface and in the Langmuir–Blodgett (LB) films on solid substrates. Measurements of surface pressure vs area isotherms, surface potential measurements, UV–visible (vis) absorption spectroscopy, Brewster angle microscopy (BAM), and atomic force microscopy (AFM) were performed. Despite not having a typical amphiphilic molecular structure, the derivatives formed stable films on the water surface. They could also undergo repeated photoisomerization in all of the investigated thin-film configurations. The observations suggest that in the films at the air–water interface, the molecules first exhibit a conformational change, and then they reorient to an energetically more favored orientation. In the LB films transferred onto solid substrates, the isomerization process occurs on a similar time scale as in solution. However, the isomerization efficiency is about an order of magnitude lower than that in solution. Our results show that DNA nucleobases functionalized with azobenzene moieties are suitable candidates for the fabrication of photoactive two-dimensional (2D) materials that can provide all beneficial functionalities of DNA-based compounds