Travelling fronts in integrodifferential equations

We provide results of the existence, uniqueness and asymptotic behavior of travelling-wave solutions for convolution equations involving different kinds of nonlinearities (bistable, ignition and monostable). We recover for these equations most of the known results about the standard equation $\text{?u}\text{?t}\text{+u″+f(u)=0}$. Some min–max formulas are also given. To cite this article: J. Coville, L. Dupaigne, C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Structural Aspects of 5‐methylthio‐1‐oxa‐6,6a δIV‐dithia‐2‐azapentalenes

Alkylation of 5‐[1‐hydroxyiminoalkyl]‐1,2‐dithiole‐3‐thiones using methyl iodide in the presence of sodium hydroxide gives derivatives which may be considered as being 5‐methylthio‐1‐oxa‐6,6a δ^IV‐dithia‐2‐azapentalenes with quantitative yields. The structure of oxadithiazapentalene attributed to the alkylation products is founded on X‐ray analysis and NMR and IR data.     

Development of a micromachined piezoelectric microphone for aeroacoustics applications

This paper describes the design, fabrication, and characterization of a bulk-micromachined piezoelectric microphone for aeroacoustic applications. Microphone design was accomplished through a combination of piezoelectric composite plate theory and lumped element modeling. The device consists of a 1.80-mm-diam, 3-microm-thick, silicon diaphragm with a 267-nm-thick ring of piezoelectric material placed near the boundary of the diaphragm to maximize sensitivity. The microphone was fabricated by combining a sol-gel lead zirconate-titanate deposition process on a silicon-on-insulator wafer with deep-reactive ion etching for the diaphragm release. Experimental characterization indicates a sensitivity of 1.66 microVPa, dynamic range greater than six orders of magnitude (35.7-169 dB, re 20 microPa), a capacitance of 10.8 nF, and a resonant frequency of 59.0 kHz.     

111 W, 110 MHz repetition-rate, passively mode-locked TEM00Nd:YVO4 master oscillator power amplifier pumped at 888 nm

We report on an 888 nm pumped passively mode-locked TEM(00)Nd:YVO(4) oscillator providing 56 W of average power at a repetition rate of 110 MHz with 33 ps pulse duration, further amplified to 111 W in a 52% optical efficiency single-pass amplifier stage, maintaining beam quality at M(2)=1.05. Frequency doubling in a LiB(3)O(5) crystal generated up to 87 W at 532 nm, while a third harmonic power of 35 W was achieved in a nonoptimized tripling configuration, corresponding to 80% and 33% conversion efficiency.     

QuickFF: A program for a quick and easy derivation of force fields for metal‐organic frameworks from ab initio input

QuickFF is a software package to derive accurate force fields for isolated and complex molecular systems in a quick and easy manner. Apart from its general applicability, the program has been designed to generate force fields for metal‐organic frameworks in an automated fashion. The force field parameters for the covalent interaction are derived from ab initio data. The mathematical expression of the covalent energy is kept simple to ensure robustness and to avoid fitting deficiencies as much as possible. The user needs to produce an equilibrium structure and a Hessian matrix for one or more building units. Afterward, a force field is generated for the system using a three‐step method implemented in QuickFF. The first two steps of the methodology are designed to minimize correlations among the force field parameters. In the last step, the parameters are refined by imposing the force field parameters to reproduce the ab initio Hessian matrix in Cartesian coordinate space as accurate as possible. The method is applied on a set of 1000 organic molecules to show the easiness of the software protocol. To illustrate its application to metal‐organic frameworks (MOFs), QuickFF is used to determine force fields for MIL‐53(Al) and MOF‐5. For both materials, accurate force fields were already generated in literature but they requested a lot of manual interventions. QuickFF is a tool that can easily be used by anyone with a basic knowledge of performing ab initio calculations. As a result, accurate force fields are generated with minimal effort. © 2015 Wiley Periodicals, Inc.     

Graphs with No Induced Five‐Vertex Path or Antipath

We prove that a graph G contains no induced ‐vertex path and no induced complement of a ‐vertex path if and only if G is obtained from 5‐cycles and split graphs by repeatedly applying the following operations: substitution, split unification, and split unification in the complement, where split unification is a new class‐preserving operation introduced here.     

Finding Alignment: The Perceptions and Integration of the Next Generation Science Standards Practices by Elementary Teachers

Preparing elementary‐level teachers to teach in alignment with the eight Next Generation Science Standards (NGSS) practices could prove to be a daunting endeavor. However, the process may be catalyzed by leveraging elements of teacher science instruction that inherently attend to the practice standards. In this study, we investigated the science instruction of three grade 3–5 elementary‐level teachers. We used observation, interviews, and surveys to determine the level to which the teachers perceived they taught and engaged in teaching science aligned with the eight NGSS practices. We found that the teachers were partially, and intrinsically implementing several of these practices in their instruction, and at the same time could not articulate the eight NGSS practices. Our results suggest there may be ample opportunity to build on the current science instruction of elementary‐level teachers to bring their instruction into alignment with the NGSS. We found that teachers’ perceive professional development, school culture, and access to additional instructional resources to be essential to their adoption of the NGSS practices.     

Chemical-garden formation, morphology, and composition. II. Chemical gardens in microgravity

We studied the growth of metal-ion silicate chemical gardens under Earth gravity (1 g) and microgravity (μg) conditions. Identical sets of reaction chambers from an automated system (the Silicate Garden Habitat or SGHab) were used in both cases. The μg experiment was performed on board the International Space Station (ISS) within a temperature-controlled setup that provided still and video images of the experiment downlinked to the ground. Calcium chloride, manganese chloride, cobalt chloride, and nickel sulfate were used as seed salts in sodium silicate solutions of several concentrations. The formation and growth of osmotic envelopes and microtubes was much slower under μg conditions. In 1 g, buoyancy forces caused tubes to grow upward, whereas a random orientation for tube growth was found under μg conditions.