Solvent Azeotropes in Art Conservation

Solvent mixtures are often fine-tuned by art conservators for the difficult tasks of safely removing yellowed varnishes and obfuscating dirt from oil paintings. These two goals are often loosely termed “picture cleaning.” Concern has been raised over the impact of differential evaporation rates for solvents in the cleaning mixture. Differential evaporation can lead to changes in the mixture’s potency over time and potentially lead to solvent mixtures on the surface of the artwork having solubility characteristics deleterious to artists’ oil paints. Azeotropic mixtures of solvents have been proposed as an alternative for maintaining consistent solvent composition. Azeotropes are specific mixtures of two or more solvents that behave as a single solvent and maintain a constant composition at their boiling point. The azeotropes that have appeared in the art conservation literature are taken from tables of azeotropic compositions in the CRC Handbook given at their boiling point. This research examines whether these solvent blends, in particular a hexane/isopropanol combination found to be an effective cleaner in the treatment of painted royal sleighs at the Palace of Versailles, in fact behave azeotropically under room temperature evaporation conditions. For the first time, the actual evaporation behavior of this purported azeotropic mixture will be explored in depth. A range of hexane/isopropanol mixtures around the boiling point azeotrope composition have been assessed for their room temperature vapor pressure and evaporation weight loss kinetics. Aliquots of the evaporating solutions are also being analyzed chemically using gas chromatography of both the liquid phase and the vapor phase in the headspace. This research aims to provide conservators information on the evaporation of purportedly azeotropic solvent blends and to suggest new approaches to the cleaning of oil paintings

Learning from lived experiences strengths and insights of bilingual immigrant teachers

The primary purpose of this study was to closely examine the livedexperiences of a group of seven bilingual and bicultural ELL paraeducators as they transition from support positions in schools and classrooms to certified teaching positions. The emphasis was to gain understanding about the ways in which the participants' own experiences as immigrants and English language learners specially equip them to be classroom teachers. A second purpose was to inform educational practice with regard to teacher preparation and at the classroom level. This was accomplished through exploration of insights gleaned from the participants' lived-experiences and examination of the qualities and strengths they bring with them to their work as teachers. A hermeneutic phenomenological research perspective served as the conceptual approach for considering a variety of data on each of the participants. Life story interviews, reflective contributions from participants, photographic portraits, and observations of their teaching provided the substance for written portraits of the participants. Analysis during the portraiture process and through a comparison of the portraits served to inform the findings of the study. Four general conclusions were generated. First, based on their personal experiences, bilingual immigrant teachers approach the profession from a culturally responsive perspective that not only influences their instructional practices but also their advocacy for students. Second, because of their vast experiences as immigrants, second language learners and paraeducators, educators such as the ones in this study have the potential to become leaders who can guide others - including preservice and inservice educators - in issues relating to the education and welfare of culturally and linguistically diverse students and their families. Third, as they transition into their new roles as teachers, certain sociocultural factors can present challenges for bilingual immigrant paraeducators that have the potential to hinder their inclusion into the staff or faculty. Finally, linguistically and culturally diverse teacher candidates benefit from having additional support systems such as a cohort model and mentors who have experienced similar challenges, not only during their teacher preparation programs but also throughout their first years of teaching

Selective Actuation and Sensing of Antisymmetric Lamb Wave Mode Using D15 Piezoelectric Transducers

Undetected damage in aircraft can lead to catastrophic failures and loss of life. Automated embedded damage detection systems can reduce manhours and downtime due to inspection. Ultrasonic inspection has become one of the most capable methods for thin plate-like structures, such as aircraft spars, stiffeners, and skins. Piezoelectric transducers can inspect structures by generating ultrasonic Lamb waves and sensing how they propagate. Many Lamb wave modes exist at a given frequency, which makes signal interpretation challenging. Selective actuation of a single mode simplifies the signal analysis. The A0 mode has the shortest wavelength, which increases sensitivity to small defects, and its group velocity is independent of composite structure layup. Recent research has found a shear-mode d15 piezoelectric transducer will selectively actuate the A0 mode when embedded at the neutral axis of a composite structure. Precise placement of the transducer at the neutral axis is difficult due to operator error, changing manufacturing environments, and design constraints. This work studies the relationship between off-axis d15 transducer placement and A0 mode selectivity through analytical, numerical, and experimental methods. A0 selectivity was found to be 12.7 dBV at the neutral axis but dropped 4.02 dBV when moved off-axis by 5.5% of the structure thickness, a drop of approximately 0.73 dBV/% of structure’s thickness from the neutral axis

From Silence to a Whisper to Active Participation: Using Literature Circles with ELL Students

This article discusses benefits of using literature circles with ELL students to strengthen literacy skills and student confidence. Highlighting one teacher\u27s implementation of literature circles, the authors present a candid examination of areas of initial weakness and describe strategies used for improvements in subsequent rounds. A discussion of specific student growth in oral communication, attitude toward reading and improved reading comprehension is included as well as lists of resources and strategies supporting effective literature circles

Is "User Friendly" really possible in library automation?

The term user friendly has become a buzzword. Everyone would probably agree that online library systems should be approachable. However, despite efforts to make system use easier, many first-time users still feel intimidated. The major cause of user fear may be the everyday jargon used by those persons who are the corporate keepers of the Holy Grail i.e., automated library systems. Often the words used in discussing online systems are overly expressive and needlessly violent in tone. Even the term user fits this situation because it sounds drug related rather than library related.published or submitted for publicatio

Elementary classroom libraries : the importance of multicultural children's literature

Quality children's literature is an imperative component of elementary literacy instruction. Students read and interact with numerous texts over their elementary career, and one of the most utilized book collections is the classroom library. Multicultural children's literature is a branch of literature that explores diverse experiences in which students of different cultures can see themselves, or books in which students are able to develop a respect and understanding of different cultures and worldviews. The dynamic connection of multicultural children's literature and the classroom library is introduced and explored in this paper. Through survey data, I analyze the perceptions of multicultural children's literature that current Indiana K-6 elementary educators hold and to what extent they include multicultural children's literature in their classroom libraries. A survey was conducted and analyzed to determine the average size of an elementary classroom library, the percentage of multicultural children's books in classroom libraries and the opinion of multicultural children's literature held by elementary teachers.Honors CollegeThesis (B.?

Selective Actuation and Sensing of Antisymmetric Lamb Wave Mode Using D15 Piezoelectric Transducers

Undetected damage in aircraft can lead to catastrophic failures and loss of life. Automated embedded damage detection systems can reduce manhours and downtime due to inspection. Ultrasonic inspection has become one of the most capable methods for thin plate-like structures, such as aircraft spars, stiffeners, and skins. Piezoelectric transducers can inspect structures by generating ultrasonic Lamb waves and sensing how they propagate. Many Lamb wave modes exist at a given frequency, which makes signal interpretation challenging. Selective actuation of a single mode simplifies the signal analysis. The A0 mode has the shortest wavelength, which increases sensitivity to small defects, and its group velocity is independent of composite structure layup. Recent research has found a shear-mode d15 piezoelectric transducer will selectively actuate the A0 mode when embedded at the neutral axis of a composite structure. Precise placement of the transducer at the neutral axis is difficult due to operator error, changing manufacturing environments, and design constraints. This work studies the relationship between off-axis d15 transducer placement and A0 mode selectivity through analytical, numerical, and experimental methods. A0 selectivity was found to be 12.7 dBV at the neutral axis but dropped 4.02 dBV when moved off-axis by 5.5% of the structure thickness, a drop of approximately 0.73 dBV/% of structure’s thickness from the neutral axis