Cracks in rubber under tension exceed the shear wave speed

The shear wave speed is an upper limit for the speed of cracks loaded in tension in linear elastic solids. We have discovered that in a non-linear material, cracks in tension (Mode I) exceed this sound speed, and travel in an intersonic range between shear and longitudinal wave speeds. The experiments are conducted in highly stretched sheets of rubber; intersonic cracks can be produced simply by popping a balloon.Comment: 4 pages, 5 eps figure

CO Reduction to CH_3OSiMe_3: Electrophile-Promoted Hydride Migration at a Single Fe Site

One of the major challenges associated with developing molecular Fischer–Tropsch catalysts is the design of systems that promote the formation of C–H bonds from H_2 and CO while also facilitating the release of the resulting CO-derived organic products. To this end, we describe the synthesis of reduced iron-hydride/carbonyl complexes that enable an electrophile-promoted hydride migration process, resulting in the reduction of coordinated CO to a siloxymethyl (LnFe-CH_2OSiMe_3) group. Intramolecular hydride-to-CO migrations are extremely rare, and to our knowledge the system described herein is the first example where such a process can be accessed from a thermally stable M(CO)(H) complex. Further addition of H_2 to LnFe-CH_2OSiMe_3 releases CH_3OSiMe_3, demonstrating net four-electron reduction of CO to CH_3OSiMe_3 at a single Fe site

Learn And Work: A Hybrid Educational Model For Engineering Education

Traditional models of education are undergoing significant change in recent times due to evolving graduate attributes, shaped in no small part by the changing demands of modern industrial practices. Technology is one of the key elements of the factory of the future. Advances in manufacturing and digital technologies facilitate automation and offer significant benefits in a variety of areas. Academic programmes that feature industrial work placement have long been a feature of engineering education in TU Dublin. The BSc in Process Instrumentation and Automation is a three-year programme that goes further in that it evenly balances on-campus instruction with work placement. The programme was specifically devised in response to industry feedback that had identified significant skills shortages in the areas of industrial instrumentation and automation. It is a hybrid between the apprenticeship model of education (www.apprenticeship.ie) and the traditional engineering degree model and directly addresses industry\u27s immediate need for experienced graduates. Participation in the programme is sponsored by Irish Medtech Skillnet, a learning network for companies in the medical technology and engineering sector that responds to the training needs of that sector. This is one step in the lifelong learning path of a modern graduate. This paper will provide a detailed critical review of the ‘learn and work’ model; strengths, challenges and opportunities offered by this mode of engineering education

Imiglucerase in the treatment of Gaucher disease: a history and perspective

The scientific and therapeutic development of imiglucerase (Cerezyme®) by the Genzyme Corporation is a paradigm case for a critical examination of current trends in biotechnology. In this article the authors argue that contemporary interest in treatments for rare diseases by major pharmaceutical companies stems in large part from an exception among rarities: the astonishing commercial success of Cerezyme. The fortunes of the Genzyme Corporation, latterly acquired by global giant Sanofi SA, were founded on the evolution of a blockbuster therapy for a single but, as it turns out, propitious ultra-orphan disorder: Gaucher disease

Dihydrogen Adduct (Co-H₂) Complexes Displaying H-atom and Hydride Transfer

The prototypical reactivity profiles of transition metal dihydrogen complexes (M‐H₂) are well‐characterized with respect to oxidative addition (to afford dihydrides, M(H)₂) and as acids, heterolytically delivering H⁺ to a base and H⁻ to the metal. In the course of this study we explored plausible alternative pathways for H₂ activation, namely direct activation through H‐atom or hydride transfer from the σ‐H₂ adducts. To this end, we describe herein the reactivity of an isostructural pair of a neutral S = ½ and an anionic S = 0 Co‐H₂ adduct, both supported by a trisphosphine borane ligand (P₃^B). The thermally stable metalloradical, (P₃^B)Co(H₂), serves as a competent precursor for hydrogen atom transfer to ᵗBu₃ArO·. What is more, its anionic derivative, the dihydrogen complex [(P₃^B)Co(H₂)]¹⁻, is a competent precursor for hydride transfer to BEt₃, establishing its remarkable hydricity. The latter finding is essentially without precedent among the vast number of M‐H₂ complexes known

Dihydrogen Adduct (Co-H₂) Complexes Displaying H-atom and Hydride Transfer

The prototypical reactivity profiles of transition metal dihydrogen complexes (M‐H₂) are well‐characterized with respect to oxidative addition (to afford dihydrides, M(H)₂) and as acids, heterolytically delivering H⁺ to a base and H⁻ to the metal. In the course of this study we explored plausible alternative pathways for H₂ activation, namely direct activation through H‐atom or hydride transfer from the σ‐H₂ adducts. To this end, we describe herein the reactivity of an isostructural pair of a neutral S = ½ and an anionic S = 0 Co‐H₂ adduct, both supported by a trisphosphine borane ligand (P₃^B). The thermally stable metalloradical, (P₃^B)Co(H₂), serves as a competent precursor for hydrogen atom transfer to ᵗBu₃ArO·. What is more, its anionic derivative, the dihydrogen complex [(P₃^B)Co(H₂)]¹⁻, is a competent precursor for hydride transfer to BEt₃, establishing its remarkable hydricity. The latter finding is essentially without precedent among the vast number of M‐H₂ complexes known

Disgustingly Queer: George Kuchar's Video Diaries

In the realm of underground film and video, George Kuchar is primarily discussed in connection with his twin brother, Mike, and their trash-spectacular narratives that injected the queer underground movement in the 1960s with a taste of the bizarre. Since their amicable split, George not only left their Bronx homestead to teach at the San Francisco Art Institute until his death in 2011, but also made a significant switch from 16mm film to video in 1985. By switching to this more affordable and accessible format, George embarked on what would become a vast body of diaristic videos. Kuchar kept some of the thematic foundations from his collaborative films with Mike, but instead focused on his cross-country travels, mainly his summer-long excursions in Oklahoma, on the lookout for tornadoes. In creating these personal videos, Kuchar presents himself as an affable, unserious person whose life is steeped in lowbrow culture or kitsch aesthetic. Kuchar focuses on the culturally and socially undervalued, and he is not interested in elevating its value status. Instead, he desires to join the muck. This thesis examines Kuchar's video diaries for their specifically queer investment in the debased and devalued. I consider them in relation to the affect of disgust, and I argue that these videos show disgust to be a complex response to "low" forms, whether aesthetic, cultural, or social. Disgust is conventionally understood as a gesture of refusal or aversion, a rejection of the object or value deemed disgusting. Kuchar's queer form of disgust, by contrast, savors impropriety and excess, and revels in the violation of boundaries.Englis

Characterisation of the heating mechanisms in a capacitively coupled argon RF discharge

A capacitively coupled rf plasma is investigated in the context of the heating mechanisms that sustain it under various conditions. These mechanisms are critically dependent on gas pressure, applied rf potential, rf current and discharge gap. Pressure ranges of 10 to 300 mTorr and rf potentials from a few Volts to several hundred Volts are investigated. The argon plasma is generated in two capacitively coupled rf systems. Plasma parameters are measured using a Langmuir probe. A microwave interferometer is used to compare density measurements with that of the probe. A current voltage monitor is used to measure the voltage, current and phase for the purpose of relating the control parameters to the plasma parameters. The design and construction of a retarding field energy analyser is presented. Plasma potential measurements using the analyser are compared with that of the Langmuir probe. Use of the analyser in electron collection mode has revealed a higher electron temperature behind the rf sheath than that measured by the Langmuir probe in the plasma. Transitions in the heating modes are investigated via plasma parameter and Electron Energy Probability Function (EEPF) measurement in the centre of the discharge. Particular attention is paid to the a-y transition. The relationship between the current voltage characteristic and the plasma parameters is considered. Pressure effects on the transition are determined. A model of the diffusion process in the capacitive rf discharge is devised and the resulting density profiles checked against known analytic solutions of the diffusion equation. A procedure to extract the ionisation profiles from experimental density measurements is devised using this model and a reconstruction algorithm. The twodimensional evolution of density and ionisation profiles is presented at low and high discharge powers over the 10 mTorr to 300 mTorr range. The total ionisation rate is compared with the theoretical ionisation rate calculated using simple particle balance equations. Disagreement in the ionisation rates is attributed to the use of unrealistic models and the assumption of uniform electron energy in the discharge. Spatially resolved EEPF measurements are made along the discharge axis. Rate coefficients for ionisation are calculated by integrating the product of the measured EEPF and the cross section for ionisation. Spatially resolved ionisation rates obtained from the coefficients are in good agreement with the measured ionisation rate profiles generated using the diffusion model and reconstruction algorithm