title: Alkynyl and poly-ynyl derivatives of carbon-tricobalt clusters

authors: Antonova, Alla B.

subjects: carbon-tricobalt cluster

abstract: A series of alkynyl-tricobalt carbonyl clusters, Co₃(μ₃-CnR)(μ-dppm)(CO)₇ [R = But, Ph, C₆H₄I, C₆H₄C≡CPh, SiMe₃, Fc, Au(PPh₃)] containing three, five or seven carbons in the chain, have been prepared by elimination of phosphine–gold(I) halides in reactions between Co₃(μ₃-CBr)(μ-dppm)(CO)₇ and Au(C≡CR)(PPh₃) or between Co₃{μ₃-CC≡CAu(PR₃)} (μ-dppm)(CO)₇ (R = Ph, tol) and IC≡CR′ (R′ = SiMe₃, Fc). The use of poly-substituted arenes or ferrocenes has enabled preparation of the complexes 1,4-{(OC)₇(μ-dppm)Co₃ (μ₃-CC≡C)}₂C₆H₃X-5 (X = H, Br), 1,3,5-{(OC)₇(μ-dppm)Co₃(μ₃-CC≡C)}₃C₆H₃ and 1,1′-{(OC)₇(μ-dppm)Co₃ (μ₃-CC≡C)}₂Fc′ [Fc′ = Fe(η-C₅H₄-)₂]. The X-ray determined molecular structures of 12 of the complexes are reported.

text: Alkynyl and poly-ynyl derivatives of carbon-tricobalt clusters A series of alkynyl-tricobalt carbonyl clusters, Co₃(μ₃-CnR)(μ-dppm)(CO)₇ [R = But, Ph, C₆H₄I, C₆H₄C≡CPh, SiMe₃, Fc, Au(PPh₃)] containing three, five or seven carbons in the chain, have been prepared by elimination of phosphine–gold(I) halides in reactions between Co₃(μ₃-CBr)(μ-dppm)(CO)₇ and Au(C≡CR)(PPh₃) or between Co₃{μ₃-CC≡CAu(PR₃)} (μ-dppm)(CO)₇ (R = Ph, tol) and IC≡CR′ (R′ = SiMe₃, Fc). The use of poly-substituted arenes or ferrocenes has enabled preparation of the complexes 1,4-{(OC)₇(μ-dppm)Co₃ (μ₃-CC≡C)}₂C₆H₃X-5 (X = H, Br), 1,3,5-{(OC)₇(μ-dppm)Co₃(μ₃-CC≡C)}₃C₆H₃ and 1,1′-{(OC)₇(μ-dppm)Co₃ (μ₃-CC≡C)}₂Fc′ [Fc′ = Fe(η-C₅H₄-)₂]. The X-ray determined molecular structures of 12 of the complexes are reported.

year: 2006-04-01

title: Scaling acoustic directional couplers using 3D printing

authors: MacDonell, Marcus Scott Glengarry

subjects: Directional coupler

abstract: Acoustic directional couplers permit separation of forward and reverse sound pressure waves. This separation opens the way to traceable, precision acoustic reflection measurements. In order to span the audio spectrum, multiple couplers will be required as each coupler only operates slightly over one octave. To reach 20 kHz or above requires very small, mechanically-precise construction. We achieve this precision using 3D printing techniques.
The Lagasse design method was used by Pennington to create a coupler that operated over a designed range of 1-2 kHz. This design was scaled to create an acoustic directional coupler with a designed range of 10-20 kHz. Because frequency scales inversely with the size of the coupler, the coupler needs to be built with a very high degree of precision. The coupler was therefore designed and modeled in SolidWorks and 3D printed to high precision. 
Characterization of the couplers was achieved using two distinct methods. The first, a preliminary measurement method to test the hypothesis and the second, a high precision automated measurement. The automation was scripted in python on a Ubuntu Linux distribution.
Future work may include an Acoustic coupler to be used in ultrasound, to do this the coupler would need to be scaled a further 2.5 times. This would likely prove difficult as the wavelengths at 50 kHz are in the order of mm, comparable with those of electromagnetic waves at 44 GHz.

text: Scaling acoustic directional couplers using 3D printing Acoustic directional couplers permit separation of forward and reverse sound pressure waves. This separation opens the way to traceable, precision acoustic reflection measurements. In order to span the audio spectrum, multiple couplers will be required as each coupler only operates slightly over one octave. To reach 20 kHz or above requires very small, mechanically-precise construction. We achieve this precision using 3D printing techniques.
The Lagasse design method was used by Pennington to create a coupler that operated over a designed range of 1-2 kHz. This design was scaled to create an acoustic directional coupler with a designed range of 10-20 kHz. Because frequency scales inversely with the size of the coupler, the coupler needs to be built with a very high degree of precision. The coupler was therefore designed and modeled in SolidWorks and 3D printed to high precision. 
Characterization of the couplers was achieved using two distinct methods. The first, a preliminary measurement method to test the hypothesis and the second, a high precision automated measurement. The automation was scripted in python on a Ubuntu Linux distribution.
Future work may include an Acoustic coupler to be used in ultrasound, to do this the coupler would need to be scaled a further 2.5 times. This would likely prove difficult as the wavelengths at 50 kHz are in the order of mm, comparable with those of electromagnetic waves at 44 GHz.

year: 2015

title: Composition Portfolio

authors: Ulenberg, Phillippa

subjects: composition portfolio

abstract: The music written for this portfolio offers creative answers to some of the challenges facing contemporary New Zealand composition, including multiculturalism.This has involved in-depth research using a variety of methods. Engagement was undertaken with linguists and musicians from Malaysia and Korea, who not only assisted with texts, but also spoke knowledgeably about their cultural traditions and past and present musical genres. The inclusion of Chinese gu-zheng in several of the works was made possible with the assistance given by Chen Xi Yao, an excellent performer who comes from a long lineage of musicians. Attending concerts given by performers of the instruments that have been used in the portfolio was essential to understanding the sounds and uses of the instruments. In addition, on-line sources include many examples of the sounds. Attendance at workshops on Māori taonga pūoro also brought the additional honour, benefits and experience of making and playing the instruments, and the opportunities to meet and work with leading makers and performers of these musical treasures. Sources of Western classical music that have been particularly influential during the writing of the portfolio are orchestral works by Igor Stravinsky, Samuel Barber and Param Vir, and the song cycles of Alban Berg and Benjamin Britten. Luciano Berio’s virtuosic piece for solo bassoon was also instructive. Experiences of composition, reflection and scholarly research underpin the portfolio and have have informed the composition of each work.

text: Composition Portfolio The music written for this portfolio offers creative answers to some of the challenges facing contemporary New Zealand composition, including multiculturalism.This has involved in-depth research using a variety of methods. Engagement was undertaken with linguists and musicians from Malaysia and Korea, who not only assisted with texts, but also spoke knowledgeably about their cultural traditions and past and present musical genres. The inclusion of Chinese gu-zheng in several of the works was made possible with the assistance given by Chen Xi Yao, an excellent performer who comes from a long lineage of musicians. Attending concerts given by performers of the instruments that have been used in the portfolio was essential to understanding the sounds and uses of the instruments. In addition, on-line sources include many examples of the sounds. Attendance at workshops on Māori taonga pūoro also brought the additional honour, benefits and experience of making and playing the instruments, and the opportunities to meet and work with leading makers and performers of these musical treasures. Sources of Western classical music that have been particularly influential during the writing of the portfolio are orchestral works by Igor Stravinsky, Samuel Barber and Param Vir, and the song cycles of Alban Berg and Benjamin Britten. Luciano Berio’s virtuosic piece for solo bassoon was also instructive. Experiences of composition, reflection and scholarly research underpin the portfolio and have have informed the composition of each work.

year: 2011