Nanoscale Phase Separation in Lithium Niobium Silicate Glass by Femtosecond Laser Irradiation

Understanding the phase transformation in glass and the morphology of related nanostructure after femtosecond laser irradiation is of great importance for fabricating functional optics, in which glass crystallization is involved to obtain nonlinear optical properties. We report on the crystallization inside lithium niobium silicate glass induced by fs laser irradiation. Energy‐dispersive X‐ray spectroscopy coupled to scanning transmission electron microscopy (STEM/EDS) and transmission electron microscopy confirm a nanoscale phase separation whereby LiNbO₃ crystals are embedded in lamella‐shaped frames of amorphous SiO₂. The obtained nanostructure may have applications in fabricating second‐order nonlinear optical devices.     

Magnetic Imaging of Cyanide‐Bridged Co‐ordination Nanoparticles Grafted on FIB‐Patterned Si Substrates

Prussian blue CsNiCr nanoparticles are used to decorate selected portions of a Si substrate. For successful grafting to take place, the Si surface needs first to be chemically functionalized. Low‐dose focused ion beam patterning on uniformly functionalized surfaces selects those portions that will not participate in the grafting process. Step‐by‐step control is assured by atomic force and high‐resolution scanning electron microscopy, revealing a submonolayer distribution of the grafted nanoparticles. By novel scanning Hall‐probe microscopy, an in‐depth investigation of the magnetic response of the nanoparticles to varying temperature and applied magnetic field is provided. The magnetic images acquired suggest that low‐temperature canted ferromagnetism is found in the grafted nanoparticles, similar to what is observed in the equivalent bulk material.     

On the implementation of the Opus coordination language

Opus is a new programming language designed to assist in coordinating the execution of multiple, independent program modules. With the help of Opus, coarse grained task parallelism between data parallel modules can be expressed in a clean and structured way. In this paper we address the problems of how to build a compilation and runtime support system that can efficiently implement the Opus constructs. Our design considers the often‐conflicting goals of efficiency and modular construction through software re‐use. In particular, we present the system requirements for an efficient Opus implementation, the Opus runtime system, and describe how they work together to provide the underlying services that the Opus compiler needs for a broad class of machines. Copyright © 2000 John Wiley & Sons, Ltd.     

Growth Kinetics and Characterization of Chromia Scales Formed on Ni–30Cr Alloy in Impure Argon at 700 °C

Oxidation of Metals - The oxidation of a Ni–30Cr alloy at 700 °C in impure argon was studied in order to provide new elements of understanding on chromia scale growth in low...     

Computer animation of human walking: a survey

This paper surveys the set of techniques developed in computer graphics for animating human walking. First we focus on the evolution from purely kinematic ‘knowledge‐based’ methods to approaches that incorporate dynamic constraints or use dynamic simulations to generate motion. Then we review the recent advances in motion editing that enable the control of complex animations by interactively blending and tuning synthetic or captured motions. Copyright © 1999 John Wiley & Sons, Ltd.     

Quartz resonator instabilities under cryogenic conditions

The phase noise of a quartz crystal resonator working at liquid helium temperatures is studied. Measurement methods and the device environment are explained. The phase noise is measured for different resonance modes, excitation levels, amount of operating time, device orientations in relation to the cryocooler vibration axis, and temperatures. Stability limits of a frequency source based on such devices are evaluated in the present measurement conditions. The sources of phase flicker and white noises are identified. Finally, the results are compared with previous works.     

Novel “Vibrating Wire Like” NEMS and MEMS Structures for Low Temperature Physics

Using microfabrication techniques, it has become possible to make mechanical devices with dimensions in the micro and even in the nano scale domain. Allied to low temperature techniques, these systems have opened a new path in physics with the ultimate goal of reaching the quantum nature of a macroscopic mechanical degree of freedom (LaHaye et al. in Science 304:74, 2004). Within this field, materials research plays a significant role. It ranges from the fundamental nature of the dissipation mechanisms at the lowest temperatures, to the non-linear behavior of mechanical oscillators. We present experimental results on cantilever structures mimicking the well known “vibrating wire” technique, which present many advantages as far as the mechanical studies are concerned: the measurement is phase-resolved, they can be magnetomotive and electrostatically driven, and support extremely large displacements. Moreover, these devices can be advantageously used to study quantum fluids, making the link with conventional low temperature physics.     

Kinetics and mechanism of the reaction between maleic anhydride and fatty acid esters and the structure of the products

Alkenyl succinic anhydrides (ASA) were obtained by reaction between maleic anhydride and high‐oleic sunflower oil (HOSO) esters. A kinetics study of the maleinization of alkyl esters indicated that the maleinization reaction was second order overall and first order with respect to the individual reactants, and the activation energy was 77.2 ± 3.3 kJ/mol in the investigated temperature range (185–225 °C). These results showed that the cis configuration and the central position of the double bond in HOSO esters facilitate the maleinization of the latter. On the contrary, the length of the linear ester moiety had no influence on the course of the maleinization reaction. Moreover, new evidence demonstrates that there are two different reaction mechanisms: ene‐reaction and addition in allylic position with a 2 : 1 ratio, respectively. This ratio was constant throughout the reaction, thus indicating that these mechanisms are independent.