Author
Pierre Wiltzius
Bio: Pierre Wiltzius is an academic researcher from University of California, Santa Barbara. The author has contributed to research in topics: Photonic crystal & Metamaterial. The author has an hindex of 7, co-authored 9 publications receiving 964 citations.
Papers
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TL;DR: In this article, the fractal dimension of colloidal aggregates of small silica particles is measured by both light and x-ray scattering, showing that the aggregates are fractal.
Abstract: Measurement of the fractal dimension, $D$, of colloidal aggregates of small silica particles is reported. We observe power-law decay of the structure factor $[S(k)\ensuremath{\sim}{k}^{\ensuremath{-}D}]$ by both light and x-ray scattering showing that the aggregates are fractal. $D$ is found to be 2.12\ifmmode\pm\else\textpm\fi{}0.05, which is intermediate between recent numerical results for the kinetic models of diffusion-limited aggregation ($D=2.5$) and cluster aggregation ($D=1.75$), but is rather close to the value for lattice animals ($D=2.0$), which are equilibrium structures.
637 citations
TL;DR: The 3D-template-directed epitaxy of group III-V materials, which enables formation of 3D structured optoelectronic devices and illustrates the power of this technique by fabricating an electrically driven 3D photonic crystal LED.
Abstract: Three-dimensional photonic devices are of interest as light emitters, detectors or waveguides. However, so far their fabrication has remained a challenge. The template-directed epitaxy of three-dimensional semiconductor structures now offers a new strategy for the realization of photonic devices, demonstrated by the realization of a three-dimensional photonic crystal light-emitting diode.
124 citations
TL;DR: In this article, a preuve experimentale du fait que, des solutions de polymeres flexibles sont caracterises par une longueur universelle dependant de la concentration qui est aisement mise en loi d'echelle pour etre independante de la masse moleculaire and de la qualite du solvant.
Abstract: Premiere preuve experimentale du fait que, des solutions de polymeres flexibles sont caracterises par une longueur universelle dependant de la concentration qui est aisement mise en loi d'echelle pour etre independante de la masse moleculaire et de la qualite du solvant
92 citations
TL;DR: In this paper, the authors report experimental results for a dynamic length scale as a function of polymer concentration for various molecular weight polystyrenes in the two solvents toluene and methyl ethyl ketone.
Abstract: We report experimental results for a dynamic length scale ${\ensuremath{\xi}}_{H}$ as a function of polymer concentration $c$ for various molecular weight polystyrenes in the two solvents toluene and methyl ethyl ketone. We find that the quantity $\frac{{\ensuremath{\xi}}_{H}}{{R}_{H}}$ is a function only of the reduced concentration $\mathrm{kc}$, where ${R}_{H}$ is the hydrodynamic radius and $k$ is determined from a virial expansion of the diffusion coefficient. However, the dynamic and static length scales are not proportional.
49 citations
TL;DR: Measurements of the osmotic susceptibility and correlation length for the pseudobinary mixture of guaiacol plus glycerol-water as a function of temperature and water content are reported.
Abstract: We report measurements of the osmotic susceptibility and correlation length for the pseudobinary mixture of guaiacol ($o$-methoxy phenol) plus glycerol-water as a function of temperature and water content $x[x\ensuremath{\equiv}\mathrm{weight}\mathrm{of}\mathrm{water}/(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{plus}\mathrm{weight}\mathrm{of}\mathrm{glycerol})]$. This system exhibits a limited two-phase region which vanishes for $xl{x}_{0}\ensuremath{\simeq}0.0137$. We observed a smooth transition from nearly Ising-type behavior for $x\ensuremath{\gtrsim}4{x}_{0}$ through a non-power-law regime to doubled exponents for $x\ensuremath{\simeq}{x}_{0}$ and saturating divergences with doubled exponents for $xl{x}_{0}$.
46 citations
Cited by
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
Journal Article•
TL;DR: In this article, a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators were developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of 3D micro-optical and micromechanical structures, including photonic-bandgap-type structures.
Abstract: Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.
1,833 citations
TL;DR: In this article, a review of colloidal processing of ceramics is presented with an emphasis on interparticle forces, suspension rheology, consolidation techniques, and drying behavior.
Abstract: Colloidal processing of ceramics is reviewed with an emphasis on interparticle forces, suspension rheology, consolidation techniques, and drying behavior. Particular attention is given to the scientific concepts that underpin the fabrication of particulate-derived ceramic components. The complex interplay between suspension stability and its structural evolution during colloidal processing is highlighted.
1,211 citations
TL;DR: In this article, the authors present a review of scattering and absorption of light by fractal aggregates, which are typically diffusion limited cluster aggregates with fractal dimensions of D.
Abstract: This paper presents a review of scattering and absorption of light by fractal aggregates. The aggregates are typically diffusion limited cluster aggregates (DLCA) with fractal dimensions of D
1,027 citations
Book•
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27 Oct 1994
TL;DR: The nature of fractals and the use of fractal instead of classical scaling concepts to describe the irregular surfaces, structures, and processes exhibited by physiological systems are described in this paper.
Abstract: The nature of fractals and the use of fractals instead of classical scaling concepts to describe the irregular surfaces, structures, and processes exhibited by physiological systems are described. The mathematical development of fractals is reviewed, and examples of natural fractals are cited. Relationships among power laws, noise, and fractal time signals are examined. >
968 citations