A Comparative Study Of Directed Laboratory And Lecture Demonstration As Methods Of Instruction In Teaching Botany To High School Students

A controlled investigation of green plants as the most important food factories of the world has been made in order to contribute more information upon the issue. Stated more specifically, the problems of this experimental study were the following: To determine which of the two methods, if either, is superior as a procedure for learning. To determine whether laboratory experiments are more effective than lecture-demonstration in training students to think clearly, to correlate and retain facts; and finally, to draw logical conclusions. To determine, if possible, which method stimulated the greater amount of pupil interest

Reflection hologram solar spectrum-splitting filters

In this paper we investigate the use of holographic filters in solar spectrum splitting applications. Photovoltaic (PV) systems utilizing spectrum splitting have higher theoretical conversion efficiency than single bandgap cell modules. Dichroic band-rejection filters have been used for spectrum splitting applications with some success however these filters are limited to spectral control at fixed reflection angles. Reflection holographic filters are fabricated by recording interference pattern of two coherent beams at arbitrary construction angles. This feature can be used to control the angles over which spectral selectivity is obtained. In addition focusing wavefronts can also be used to increase functionality in the filter. Holograms fabricated in dichromated gelatin (DCG) have the benefit of light weight, low scattering and absorption losses. In addition, reflection holograms recorded in the Lippmann configuration have been shown to produce strong chirping as a result of wet processing. Chirping broadens the filter rejection bandwidth both spectrally and angularly. It can be tuned to achieve spectral bandwidth suitable for spectrum splitting applications. We explore different DCG film fabrication and processing parameters to improve the optical performance of the filter. The diffraction efficiency bandwidth and scattering losses are optimized by changing the exposure energy, isopropanol dehydration bath temperature and hardening bath duration. A holographic spectrum-splitting PV module is proposed with Gallium Arsenide (GaAs) and silicon (Si) PV cells with efficiency of 25.1% and 19.7% respectively. The calculated conversion efficiency with a prototype hologram is 27.94% which is 93.94% compared to the ideal spectrum-splitting efficiency of 29.74%

Comparing physicochemical properties of printed and hand cast biocements designed for ligament replacement

In order to combat the low regenerative capabilities of ligaments, full `bone to bone' replacements are required, which will integrate with bone while providing a smooth transition to the replacement soft tissue (tissues surrounding organs in the body, not being bone). This study investigated the use of three-dimensional powder printing technology to form calcium phosphate brackets, previously used for forming bespoke scaffold geometries, to 95±0·1% accuracy of their original computer aided design. The surface and internal structures of the printed samples were characterised both chemically and morphologically and compared with hand moulded cements in the dry state and after 3 days of immersion in phosphate buffered saline. X-ray diffraction, Raman spectroscopy and SEM all showed the presence of brushite in the hand moulded samples and brushite and monetite within the printed samples. Furthermore, the printed structures have a higher level of porosity in the dry state in comparison to the hand moulded samples (36±2·2% compared to 24±0·7%) despite exhibiting a compressive strength of almost double the hand cast material. Although the compressive strength of the printed cements decreases after the 3 day immersion, there was no significant difference between the printed and hand moulded cements under the same conditions. Three-dimensional powder printing technology has enabled the manufacture of bespoke calcium phosphate brackets with properties similar to those reported for hand moulded cements

Transistors

Contains reports on eight research projects.Lincoln Laboratory under Contract AF19(122)-45

Transistors

Contains reports on six research projects

Structural changes to resorbable calcium phosphate bioceramic aged <i>in vitro</i>

This work investigates the effect of mammalian cell culture conditions on 3D printed calcium phosphate scaffolds. The purpose of the studies presented was to characterise the changes in scaffold properties in physiologically relevant conditions. Differences in crystal morphologies were observed between foetal bovine serum-supplemented media and their unsupplemented analogues, but not for supplemented media containing tenocytes. Scaffold porosity was found to increase for all conditions studied, except for tenocyte-seeded scaffolds. The presence of tenocytes on the scaffold surface inhibited any increase in scaffold porosity in the presence of extracellular matrix secreted by the tenocytes. For acellular conditions the presence or absence of sera proteins strongly affected the rate of dissolution and the distribution of pore diameters within the scaffold. Exposure to high sera protein concentrations led to the development of significant numbers of sub-micron pores, which was otherwise not observed. The implication of these results for cell culture research employing calcium phosphate scaffolds is discussed

Determination of the physical environment within the Chlamydia trachomatis inclusion using ion-selective ratiometric probes

Chlamydia trachomatis is an obligate intracellular bacterium with a biphasic life cycle that takes place entirely within a membrane-bound vacuole termed an inclusion. The chlamydial inclusion is non-fusogenic with endosomal or lysosomal compartments but intersects a pathway involved in transport of sphingomyelin from the Golgi apparatus to the plasma membrane. The physical conditions within the mature chlamydial inclusion are unknown. We used ratiometric imaging with membrane-permeant, ion-selective fluorescent dyes for microanalyis of the physical environment within the inclusion. Determination of H + , Na + , K + and Ca 2 + concentrations using CFDA (carboxy fluorescein diacetate) or BCECF-AM (2 ′ ,7 ′ -bis (2-carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester, SBFI-AM, PBFI-AM and fura-PE3-acetomethoxyester (Fura-PE3-AM), respectively, indicated that all ions assayed within the lumenal space of the inclusion approximated the concentrations within the cytoplasm. Stimulation of purinergic receptors by addition of extracellular ATP triggered a dynamic Ca 2 + response that occurred simultaneously within the cytoplasm and interior of the inclusion. The chlamydial inclusion thus appears to be freely permeable to cytoplasmic ions. These results have implications for nutrient acquisition by chlamydiae and may contribute to the non-fusogenicity of the inclusion with endocytic compartments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72253/1/j.1462-5822.2002.00191.x.pd

Glycan labeling strategies and their use in identification and quantification

Most methods for the analysis of oligosaccharides from biological sources require a glycan derivatization step: glycans may be derivatized to introduce a chromophore or fluorophore, facilitating detection after chromatographic or electrophoretic separation. Derivatization can also be applied to link charged or hydrophobic groups at the reducing end to enhance glycan separation and mass-spectrometric detection. Moreover, derivatization steps such as permethylation aim at stabilizing sialic acid residues, enhancing mass-spectrometric sensitivity, and supporting detailed structural characterization by (tandem) mass spectrometry. Finally, many glycan labels serve as a linker for oligosaccharide attachment to surfaces or carrier proteins, thereby allowing interaction studies with carbohydrate-binding proteins. In this review, various aspects of glycan labeling, separation, and detection strategies are discussed

Glacial Geomorphology and Snow-Lines of Younger Quaternary around the Yari-Hotaka Mountain Range, Northern Alps, Central Japan

Glacial geomorphology and snow-lines of Younger Quaternary around the Yari- Hotaka Mountain Range, Northern Alps, Central Japan / M. Ito ; G. Vorndran. - In: Polarforschung. 53. 1983. S. 75-89

Strategisches Management im internationalen Wettbewerb: Rahmenbedingungen und Konzeptionsansaetze internationaler Unternehmensstrategien unter Beruecksichtigung verschiedenartiger Wettbewerbsumfelder

Available from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel A 190641 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman