Materials Literature
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We report an in situ observation of water condensation and evaporation on lotus leaf surfaces inside an environmental scanning electron microscope. The real-time observation shows, at the micrometer length scale, how water drops grow to large contact angles during water condensation, and decrease in size and contact a…
Aluminum hydride polymorphs (alpha-AlH3, beta-AlH3, and gamma-AlH3) were prepared by organometallic synthesis. Hydrogen capacities approaching 10 wt % at desorption temperatures less than 100 degrees C have been demonstrated with freshly prepared AlH3. The temperature-dependent rate constants were determined by measur…
We calculate the magnetic interactions between two nearest neighbor substitutional magnetic ions (Co or Mn) in ZnO by means of density functional theory and compare it with the available experimental data. Using the local spin density approximation we find a coexistence of ferro- and antiferromagnetic couplings for Zn…
We theoretically demonstrate that at a finite temperature, an effective wall thickness of a single walled carbon nanotube (SWNT) should be $W=W_s+W_d$, where $W_s$ is the static thickness defined as the extension of the outmost electronic orbit and $W_d$ the dynamic thickness due to thermal vibration of atoms. Both mo…
Artificially fabricated structures with periodically modulated parameters such as photonic crystals offer novel ways of controlling the flow of light due to the existence of a range of forbidden frequencies associated with a photonic band gap. It is believed that modulation of the refractive index in all three spatial…
We study the presence of ferromagnetism in the phase diagram of the two-dimensional honeycomb lattice close to half-filling (graphene) as a function of the strength of the Coulomb interaction and doping. We show that exchange interactions between Dirac fermions can stabilize a ferromagnetic phase at low doping when th…
Large-scale Ni-doped ZnO nanowire (NW) arrays are grown. The electrical conductivity of a single Ni-doped ZnO NW has been increased for 30 times. The photoluminescence (PL) spectrum of the doped ZnO NWs has a red shift, suggesting possible doping induced band edge bending. The doped NW arrays could be the basis for bu…
We found direct experimental evidence for an orbital switching in the V 3d states across the metal-insulator transition in VO2. We have used soft-x-ray absorption spectroscopy at the V L2,3 edges as a sensitive local probe and have determined quantitatively the orbital polarizations. These results strongly suggest tha…
We investigate, for two water models displaying a liquid–liquid critical point, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid–liquid critical point. We find a correlation between the dynamic crossover and the locus of specific heat maxima \documentclass[12p…
We show that post growth annealing of GaMnAs under As capping at temperatures in the range of 180-210 C leads to significant surface modifications. Depending on GaMnAs layer thickness and composition, we obtain either a smooth continuous reacted (MnAs) surface layer or 3D islands (quantum dots). The surface modificati…
Small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) were used to probe the final morphology of linear and novel branched poly(ethylene terephthalate) (PET) samples having undergone shear‐induced crystallization. The branched PET samples were produced via a reactive extrusion process designed…
In this study, an analysis has been made of electrochemical noise (EN) signals of potential and current obtained on immersing samples of the Alloy AA5083 (UNS A95083) in solutions of sodium chloride (NaCl). These signals have been processed using the calculation of the Hurst exponent, a tool derived from the theory of…
We studied the voltage–dependent liquid crystal (LC) dynamic stability corresponding to the pixel edge shape in the fringe field switching (FFS) mode. LC dynamics is very unstable near the edge of the pixel slit, where there is a horizontally different field direction compared with the active region, particularly when…
There has been extensive research activity since the discovery of fatigue free La-doped Bi 4 Ti 3 O 12 films on Pt electrodes. These films show superior ferroelectric properties and require a lower deposition temperature than the previously discovered SrBi 2 Ta 2 O 9 . Substitution of Bi by lanthanide elements other t…
In this research, a new method is developed for grading various types of yarn for appearance using image analysis and an artificial neural network. The images of standard yarn boards were analyzed by image analysis and four different faults factors were defined and measured for each series of yarn counts. For each ser…
In the variable pressure scanning electron microscope (VP-SEM) the incident electrons pass through a gaseous environment and the beam is scattered by these interactions. We show here that the experimental intensity profile of the scattered beam can be described as Gaussian in form to a high level of accuracy. This pro…
Le présent travail concerne la détermination des propriétés mécaniques des âmes nids d'abeilles de forme hexagonale et de leurs versions sur-expansées rectangulaires. Ces âmes en papiers Nomex® sont présentes sur les voiliers multicoques de courses océaniques entièrement réalisés à partir de sandwichs à peaux de tissu…
The microspinning technology has generally been used for cotton in the case of small scale spinning test methods (50 gram fibres). One type of silk fibre waste -pierced cocoonprepared previously as short silk fibre with cut length of 35 mm is blended with cotton fibre to obtain further data concerning two blending tec…
The electronic structure and plastic properties are investigated for a number of alkali halide crystals (CsCl, CsBr, CsI). First-principles calculations are carried out within the Hartree-Fock and density-functional theory approximations using several variants of the exchange-correlation functional, including the hybr…
Based on typification in Ehrenberg's original material, the nomenclature and taxonomy of Gyrosigma fasciola (Ehrenberg) J.W. Griffith et Henfrey are discussed. This diatom is compared to two morphologically similar taxa, Gyrosigma sulcatum (Grunow in Cleve & Grunow) Frenguelli and Gyrosigma arcuatum (Donkin) Sterrenbu…