B. K. McCoy

Spontaneous and field-induced mesomorphism of a silyl-terminated bent-core liquid crystal as determined from second-harmonic generation and resonant X-ray scattering

The polarity and structure of the phases of a liquid crystal constituted by thiophene-based bent-core molecules is investigated by means of optical second-harmonic generation (SHG), and resonant and conventional X-ray diffraction. The material studied is representative of a wide family of mesogens that contain silyl groups at the ends of the chains. These bulky terminal groups have been reported to give rise to smectic phases showing ferroelectric switching. However, the analysis of the SHG signal before and after application of electric fields has allowed us to establish unambiguously that the reported ferroelectricity is not intrinsic to the material but stabilized by the cell substrates once an electric field has been applied. In addition, the results obtained from resonant X-ray diffraction indicate that virgin samples have antiferroelectric undulated synclinic smectic structures.

Liquid crystal mesophases beyond commensurate four-layer periodicity

For more than one decade, were the only three confirmed commensurate SmC* variant phases with periodicities less than or equal four layers. In 2006, employing ellipsometry and resonant X-ray diffraction (RXRD), our research team first discovered a new liquid crystal mesophase having a six-layer periodicity in one ternary mixture which includes one sulfur-containing compound. From our ellipsometric results, this phase showed antiferroelectric-like optical response. This novel discovery inspired renewed interest to search for liquid crystal mesophases with commensurate periodicities greater than four layers. Soon after, another mesophase having a six-layer structure and showing a ferrielectric-like dielectric response, instead, was uncovered by RXRD measurements on a different binary mixture which has one bromine-containing compound. Meanwhile mesophases having a 5-, 8-, 12- or 15-layer periodicity were reported. However, numerous questions remain to be addressed associated with these unusual reported phases. Theoretical models giving rise to mesophases with periodicities greater than four layers have been developed; but, to date, none of them have provided satisfactory explanations of all the physical phenomena related to the mesophases exhibiting a six-layer structure. Moreover, the question “what is the source of long-range interactions between liquid-like smectic layers, which are responsible for establishing mesophases with long periodicities and mean-field behavior of the smectic-A–smectic-C transition?” remains unanswered for more than three decades.

Developing a Program-Level Faith Integration Curriculum: A Case Study From Physics

Integrating faith with academics possesses significant benefits for students, because it connects major disciplines to students’ personal values and goals, prepares students to be effective and faithful professionals in their discipline and vocation, and develops students’ understanding of the nature of their discipline. However, to access these advantages, thoughtful teaching to integrate faith with the discipline is required. This article describes the development and implementation process for a faith integration curriculum that parallels discipline-specific content throughout all courses in an undergraduate physics major. The physics faith integration curriculum encompasses four themes: characteristics of scientists, nature of science and scientific worldview, the role of science and technology in society, and theological implications of physics. Key topics within these themes are assigned to each course in the major. Each theme is introduced in first-year and sophomore courses and is further developed in upper-level courses. The process by which the faith integration curriculum has been developed and the theme-based structure of the curriculum may serve as a useful template for other disciplines and institutions.

Inquiry-based honors physics labs

We report on a new set of laboratories for our Freshman Honors Physics Course. The new labs are inquiry-based, and allow students to design, execute and analyze their own experiments. The students usually analyzed their experiments by simulating them, using realistic motion techniques in python or spreadsheets. Students presented their finished analyses to the rest of the class with Microsoft PowerPoint. The labs were quite successful, though we did not do any rigorous assessment.