Kitchen Chemistry: History and Development

A description of the history and development of the first Kitchen Chemistry science show, together with descriptions of most of the demonstrations

Restorative Dentistry: Dental composite depth of cure with halogen and blue light emitting diode technology

Objectives To test the hypothesis that a blue light emitting diode (LED) light curing unit (LCU) can produce an equal dental composite depth of cure to a halogen LCU adjusted to give an irradiance of 300 mWcm–2 and to characterise the LCU's light outputs. Materials and methods Depth of cure for three popular composites was determined using a penetrometer. The Student's t test was used to analyse the depth of cure results. A power meter and a spectrometer measured the light output. Results The spectral distribution of the LCUs differed strongly. The irradiance for the LED and halogen LCUs were 290 mWcm–2 and 455 mWcm–2, when calculated from the scientific power meter measurements. The LED LCU cured all three dental composites to a significantly greater (P < 0.05) depth than the halogen LCU. Conclusions An LED LCU with an irradiance 64% of a halogen LCU achieved a significantly greater depth of cure. The LCU's spectral distribution of emitted light should be considered in addition to irradiance as a performance indicator. LED LCUs may have a potential for use in dental practice because their performance does not significantly reduce with time as do conventional halogen LCUs

Kitchen Chemistry: practical chemistry with simple equipment and readily available materials

The Kitchen Chemistry Science Show uses readily available materials and unsophisticated equipment. The development of the show is outlined and each of the demonstrations is described in detail. For each demonstration there is an explanation of the demonstration and, where appropriate, a suggestion for an extension to a whole class activity. Indications of safety precautions are also discussed. Further development of the Kitchen Chemistry Outreach Project is then outlined with a description of future plans

Generating large question banks of graded questions with tailored feedback and its effect on student performance

Formative assessments have been developed to give students practice with simple mathematical manipulations necessary in physical chemistry. A series of computer programs has been used to generate large pools of questions to accompany a core undergraduate physical chemistry module. In each assessment the questions are graded to increase the cognitive load gradually and feedback is tailored to each individual response. Furthermore, the assessments are arranged in a “daisy chain” to ensure that one is completed before the next may be attempted. The difference in terminal examination results between cohorts prior and post intervention is presented. There appears to have been a positive effect on the examination performance of the post intervention students

The photochemistry and photophysics of a series of alpha octa(alkyl-substituted) silicon, zinc and palladium phthalocyanines

Photophysical and photochemical measurements have been made on a series of novel alpha octa(alkyl-substituted) silicon, zinc and palladium phthalocyanines for which the synthesis is outlined. Fluorescence quantum yields and lifetimes, triplet quantum yields and lifetimes and singlet delta oxygen quantum yields were measured in 1% v/v pyridine in toluene. The effects of varying central atom and addition of alkyl substituents relative to unsubstituted parent molecules, zinc phthalocyanine (ZnPc) and silicon phthalocyanine (SiPc), are discussed. All phthalocyanines studied exhibit absorption and emission maxima in the region of 680–750 nm with molar absorptivity of the Q-band 105 M−1 cm−1. The series of compounds also exhibited triplet quantum yields of 0.65–0.95 and singlet oxygen quantum yields of 0.49–0.93

Interrelation between protein intake, endogenous nitrogen excretion, and biological value of protein.

Digitized 2007 AES.Includes bibliographical references (page 14)

Endogenous nitrogen and basal energy relationships during growth.

Publication authorized March 15, 1935.Digitized by the MU Libraries Digitization Unit for the University of Missouri--Columbia on 2012-05. Original color tiffs converted to grayscale, 400 dpi, with editing to remove paper texture and image noise. Access versions: PDF 1.6v text searchable

Vibronic excitations of large molecules in solution studied by two-color pump–probe experiments on the 20 fs time scale

The ultrafast vibronic response of organic dye molecules in solution is studied in pump–probe experiments with 30 fs excitation pulses resonant to S0–Sn transitions. The molecular dynamics is probed either by pulses at the same spectral position or by 20 fs pulses overlapping with both the S0–S1 absorption and emission bands. Three contributions on distinctly different time scales are observed in the temporally and spectrally resolved two-color measurements. In the regime below 50 fs, a strong coherent coupling of the S0–Sn and the S0–S1 transitions occurs that is due to coherent vibrational motions in the electronic ground state. This signal is superimposed on the fast bleaching of the electronic ground state, resulting in a steplike increase of transmission. In the range of the S0–S1 emission band, one finds a subsequent picosecond rise of transmission that is due to stimulated emission from vibronic S1 states. The data demonstrate that the relaxation of Sn states directly populated by the pump pulses is much faster than the buildup of stimulated emission. This gives insight into different steps of intramolecular vibronic redistribution and is compared to the Sn–S1 relaxation in other molecules

Course of energy and nitrogen metabolism in the domestic fowl during 48-day fasts...

Publication authorized November 22, 1932.Digitized 2007 AES.Includes bibliographical references (page 28)

Endogenous urinary nitrogen and total creatinine excretion in rats as functions of dietary protein level, time on N-free diets, age, body weight, and basal metabolism.

Publication authorized June 1, 1933."This bulletin contains a part of the dissertation of Ural S. Ashworth, presented to the Graduate School of the University of Missouri, in partial fulfillment of the requirements for the degree of Doctor of Philosophy"--P. [4].Digitized 2007 AES.Includes bibliographical references (page 33)