Showing papers by "Xiang Zhang published in 2009"
TL;DR: It is shown that breast cancer metastasis to the brain involves mediators of extravasation through non-fenestrated capillaries, complemented by specific enhancers of blood–brain barrier crossing and brain colonization.
Abstract: The molecular basis for breast cancer metastasis to the brain is largely unknown. Brain relapse typically occurs years after the removal of a breast tumour, suggesting that disseminated cancer cells must acquire specialized functions to take over this organ. Here we show that breast cancer metastasis to the brain involves mediators of extravasation through non-fenestrated capillaries, complemented by specific enhancers of blood-brain barrier crossing and brain colonization. We isolated cells that preferentially infiltrate the brain from patients with advanced disease. Gene expression analysis of these cells and of clinical samples, coupled with functional analysis, identified the cyclooxygenase COX2 (also known as PTGS2), the epidermal growth factor receptor (EGFR) ligand HBEGF, and the alpha2,6-sialyltransferase ST6GALNAC5 as mediators of cancer cell passage through the blood-brain barrier. EGFR ligands and COX2 were previously linked to breast cancer infiltration of the lungs, but not the bones or liver, suggesting a sharing of these mediators in cerebral and pulmonary metastases. In contrast, ST6GALNAC5 specifically mediates brain metastasis. Normally restricted to the brain, the expression of ST6GALNAC5 in breast cancer cells enhances their adhesion to brain endothelial cells and their passage through the blood-brain barrier. This co-option of a brain sialyltransferase highlights the role of cell-surface glycosylation in organ-specific metastatic interactions.
1,638 citations
TL;DR: The optical 'carpet' cloak is designed using quasi-conformal mapping to conceal an object that is placed under a curved reflecting surface by imitating the reflection of a flat surface and enables broadband and low-loss invisibility at a wavelength range of 1,400-1,800 nm.
Abstract: Invisibility devices have captured the human imagination for many years. Recent theories have proposed schemes for cloaking devices using transformation optics and conformal mapping. Metamaterials, with spatially tailored properties, have provided the necessary medium by enabling precise control over the flow of electromagnetic waves. Using metamaterials, the first microwave cloaking has been achieved but the realization of cloaking at optical frequencies, a key step towards achieving actual invisibility, has remained elusive. Here, we report the first experimental demonstration of optical cloaking. The optical 'carpet' cloak is designed using quasi-conformal mapping to conceal an object that is placed under a curved reflecting surface by imitating the reflection of a flat surface. The cloak consists only of isotropic dielectric materials, which enables broadband and low-loss invisibility at a wavelength range of 1,400-1,800 nm.
1,318 citations
TL;DR: Tumor self-seeding could explain the relationships between anaplasia, tumor size, vascularity and prognosis, and local recurrence seeded by disseminated cells following ostensibly complete tumor excision.
1,172 citations
TL;DR: In this article, a dielectric optical cloak is designed using quasi-conformal mapping to conceal an object that is placed under a curved reflecting surface which imitates the reflection of a flat surface.
Abstract: Invisibility or cloaking has captured human's imagination for many years. With the recent advancement of metamaterials, several theoretical proposals show cloaking of objects is possible, however, so far there is a lack of an experimental demonstration at optical frequencies. Here, we report the first experimental realization of a dielectric optical cloak. The cloak is designed using quasi-conformal mapping to conceal an object that is placed under a curved reflecting surface which imitates the reflection of a flat surface. Our cloak consists only of isotropic dielectric materials which enables broadband and low-loss invisibility at a wavelength range of 1400-1800 nm.
955 citations
TL;DR: The presence of strong chirality in the terahertz metamaterial lifts the degeneracy for the two circularly polarized waves and allows for the achievement of negative refractive index without requiring simultaneously negative permittivity and negative permeability.
Abstract: We experimentally demonstrate a chiral metamaterial exhibiting negative refractive index at terahertz frequencies. The presence of strong chirality in the terahertz metamaterial lifts the degeneracy for the two circularly polarized waves and allows for the achievement of negative refractive index without requiring simultaneously negative permittivity and negative permeability. The realization of terahertz chiral negative index metamaterials offers opportunities for investigation of their novel electromagnetic properties, such as negative refraction and negative reflection, as well as important terahertz device applications.
905 citations
TL;DR: It is reported that a gene expression signature of Src activation is associated with late-onset bone metastasis in breast cancer, independent of hormone receptor status or breast cancer subtype.
646 citations
TL;DR: The experimental demonstration of an acoustic hyperlens that magnifies subwavelength objects by gradually converting evanescent components into propagating waves and achieves deep-subwavelength resolution with low loss over a broad frequency bandwidth is reported.
Abstract: Like their optical counterparts, acoustic metamaterials are capable of manipulating sound waves in unusual ways. An acoustic hyperlens is now demonstrated that is capable of magnifying subwavelength acoustic waves, and could therefore find applications in medical imaging or underwater sonar. Acoustic metamaterials can manipulate sound waves in surprising ways, which include collimation, focusing, cloaking, sonic screening and extraordinary transmission1,2,3,4,5,6,7,8,9,10,11,12,13,14. Recent theories suggested that imaging below the diffraction limit using passive elements can be realized by acoustic superlenses or magnifying hyperlenses15,16. These could markedly enhance the capabilities in underwater sonar sensing, medical ultrasound imaging and non-destructive materials testing. However, these proposed approaches suffer narrow working frequency bands and significant resonance-induced loss, which hinders them from successful experimental realization. Here, we report the experimental demonstration of an acoustic hyperlens that magnifies subwavelength objects by gradually converting evanescent components into propagating waves. The fabricated acoustic hyperlens relies on straightforward cutoff-free propagation and achieves deep-subwavelength resolution with low loss over a broad frequency bandwidth.
623 citations
TL;DR: A distinct WNT/TCF signaling program through LEF1 and HOXB9 enhances the competence of lung adenocarcinoma cells to colonize the bones and the brain.
546 citations
TL;DR: A high-Q SPP whispering-gallery microcavity that is made by coating the surface of a high- Q silica microresonator with a thin layer of a noble metal is demonstrated and Q factors of 1,376 ± 65 can be achieved in the near infrared for surface-plasmonic whispering- gallery modes at room temperature.
Abstract: Surface plasmon polaritons (SPPs) are electron density waves excited at the interfaces between metals and dielectric materials (1). Owing to their highly localized electromagnetic fields, they may be used for the transport and manipulation of photons on subwavelength scales (2-9). In particular, plasmonic resonant cavities represent an application that could exploit this field compression to create ultrasmall-mode-volume devices. A key figure of merit in this regard is the ratio of cavity quality factor, Q (related to the dissipation rate of photons confined to the cavity), to cavity mode volume, V (refs 10, 11). However, plasmonic cavity Q factors have so far been limited to values less than 100 both for visible and near-infrared wavelengths (12-16). Significantly, such values are far below the theoretically achievable Q factors for plasmonic resonant structures. Here we demonstrate a high-Q SPP whispering-gallery microcavity that is made by coating the surface of a high-Q silica microresonator with a thin layer of a noble metal. Using this structure, Q factors of 1,376 ± 65 can be achieved in the near infrared for surface-plasmonic whispering-gallery modes at room temperature. This nearly ideal value, which is close to the theoretical metal-loss-limited Q factor, is attributed to the suppression and minimization of radiation and scattering losses that are made possible by the geometrical structure and the fabrication method. The SPP eigenmodes, as well as the dielectric eigenmodes, are confined within the whispering-gallery microcavity and accessed evanescently using a single strand of low-loss, tapered optical waveguide (17, 18). This coupling scheme provides a convenient way of selectively exciting and probing confined SPP eigenmodes. Up to 49.7 per cent of input power is coupled by phase-matching control between the microcavity SPP and the tapered fibre eigenmodes.
464 citations
TL;DR: In this paper, the authors link the newly emerged field of artificial optical materials to that of celestial mechanics, thus opening the way to investigate light phenomena reminiscent of orbital motion, strange attractors and chaos, in a controlled laboratory environment.
Abstract: Einstein’s general theory of relativity establishes equality between matter–energy density and the curvature of spacetime. As a result, light and matter follow natural paths in the inherent spacetime and may experience bending and trapping in a specific region of space. So far, the interaction of light and matter with curved spacetime has been predominantly studied theoretically and through astronomical observations. Here, we propose to link the newly emerged field of artificial optical materials to that of celestial mechanics, thus opening the way to investigate light phenomena reminiscent of orbital motion, strange attractors and chaos, in a controlled laboratory environment. The optical–mechanical analogy enables direct studies of critical light/matter behaviour around massive celestial bodies and, on the other hand, points towards the design of novel optical cavities and photon traps for application in microscopic devices and lasers systems. Black holes are difficult to study experimentally, owing to their distance from us and indeed their very nature. A theoretical study suggests that optical metamaterials that exhibit behaviour that is reminiscent of that of black holes, could enable us to learn more about these and other astrophysical objects.
340 citations
TL;DR: In this article, a surface enhanced molecular detection technique with zeptomole sensitivity was proposed that relies on resonant coupling of plasmonic modes of split ring resonators and infrared vibrational modes of a self-assembled monolayer of octadecanthiol molecules.
Abstract: We report a surface enhanced molecular detection technique with zeptomole sensitivity that relies on resonant coupling of plasmonic modes of split ring resonators and infrared vibrational modes of a self-assembled monolayer of octadecanthiol molecules Large near-field enhancements at the gap of split ring resonators allow for this resonant coupling when the molecular absorption peaks overlap spectrally with the plasmonic resonance Electromagnetic simulations support experimental findings
TL;DR: In this paper, Diethylenetriamine-bacterial cellulose (EABC) was synthesized by amination with diethylENetriamines on bacterial cellulose.
TL;DR: Compared with BC, CM-BC performs better adsorption, with the value of 9.67 mg (copper)/g, 22.56 mg (lead)/g for BC and 12.42 mg ( lead/g) forCM-BC, respectively, which closely follows pseudo-second-order rate model and the adsorptive isotherm data well follows the Langmuir model.
01 Jan 2009
TL;DR: In this paper, a hybridized plasmonic-waveguide system exhibiting behavior similar to that of the electromagnetically induced transparency is presented. But the authors focus on the coupling-induced cancellation of the plasmoric resonance.
Abstract: Plasmons in nanoscale structures represent an exciting new route toward efficient manipulation of photons, especially at subwavelength scales. Of particular interest are the hybridized plasmonic systems, in which the interaction among the plasmonic elements can be utilized to tailor the optical responses. Here we demonstrate a hybridized plasmonic-waveguide system exhibiting behavior similar to that of the electromagnetically induced transparency; namely, an ultranarrow transmission line width arising from a coupling-induced cancellation of the plasmonic resonance.
TL;DR: In situ synthesis of silver chloride (AgCl) nanoparticles was carried out under ambient conditions in nanoporous bacterial cellulose (BC) membranes as nanoreactors in this article.
TL;DR: A novel, all-plasmonic nanoscopic cavity exhibiting Q-factors up to 200 at visible frequencies and the occurrence of an optimum wavelength for plasmon storage in these cavities allows for the enhancement of weak optical processes such as spontaneous emission and nonlinear optics at nanoscale dimensions.
Abstract: We experimentally demonstrate a novel, all-plasmonic nanoscopic cavity exhibiting Q-factors up to 200 at visible frequencies. The Fabry-Perot type resonator uses tall metallic fins that reflect up to 98% of incident surface plasmon to concentrate light within a subwavelength cavity mode. High aspect ratio metal fins, constructed using lithography and electroplating, reduce surface plasmon scattering out of the surface, while a short cavity length reduces the propagation loss. A simple Fabry-Perot cavity model adapted for surface plasmon dispersion and reflection describes the underlying physics of the nanocavities and the results agree well with Johnson's and Christie's permittivity data. The occurrence of an optimum wavelength for plasmon storage in these cavities allows us to clearly visualize the fundamental trade-off between propagation loss and the spatial extent of surface plasmon polaritons. The subwavelength optical mode area within these cavities enables the enhancement of weak optical processes such as spontaneous emission and nonlinear optics at nanoscale dimensions.
TL;DR: In this article, the authors synthesized and stabilized CdS nanoparticles on unique bacterial cellulose (BC) nanofibers in situ, and the obtained nanocomposite material have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transformed infrared (FTIR), thermogravimetric analysis (TGA), ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy.
TL;DR: It is found that bound gradients of netrin-1 and brain-derived neurotrophic factor can polarize the initiation and turning of axons in cultured hippocampal neurons and the diffusive printing technique is useful for studying neuronal responses induced by bound protein gradients.
Abstract: Extracellular gradients of secreted guidance factors are known to guide axon pathfinding and neuronal migration. These factors are likely to bind to cell surfaces or extracellular matrix, but whether and how they may act in bound gradients remains mostly unclear. In this study, we have developed a new technique for rapid production of stable microscopic gradients of substrate-bound proteins by covalent bonding of the proteins with an epoxy-coated glass substrate while they are diffusing in an agarose gel. Using this method, we found that bound gradients of netrin-1 and brain-derived neurotrophic factor (BDNF) can polarize the initiation and turning of axons in cultured hippocampal neurons. Furthermore, bound BDNF gradient caused attractive and repulsive polarizing response on gradients of low- and high-average density of BDNF, respectively. This novel bidirectional response to BDNF depended on the basal level of cAMP in the neuron. Finally, our data showed that the neuron's attractive response to bound BDNF gradient depended on the absolute difference rather than the relative difference in the BDNF density across the neuron, with a minimal effective difference of 1-2 BDNF molecule/mum(2) on the substrate surface. Thus, substrate-bound guidance factors are highly effective in polarizing axon initiation and growth, and the diffusive printing technique is useful for studying neuronal responses induced by bound protein gradients.
TL;DR: This work experimentally demonstrate and quantitatively measure the nanofocusing of surface plasmon polaritons in tapered metallic V-grooves down to the deep subwavelength scale - approximately lambda/40 at wavelength of 1.5 micron - with almost 50% power efficiency.
Abstract: A major challenge in optics is how to deliver and concentrate light from the micron-scale into the nano-scale. Light can not be guided, by conventional mechanisms, with optical beam sizes significantly smaller than its wavelength due to the diffraction limit. On the other hand, focusing of light into very small volumes beyond the diffraction limit can be achieved by exploiting the wavelength scalability of surface plasmon polaritons. By slowing down an optical wave and shrinking its wavelength during its propagation, optical energy can be compressed and concentrated down to nanometer scale, namely, nanofocusing. Here, we experimentally demonstrate and quantitatively measure the nanofocusing of surface plasmon polaritons in tapered metallic V-grooves down to the deep subwavelength scale - approximately lambda/40 at wavelength of 1.5 micron - with almost 50% power efficiency.
TL;DR: The High Resolution Fly's Eye (HiRes) experiment has measured the flux of ultra-high energy cosmic rays using the stereoscopic air fluorescence technique as discussed by the authors, which can be analyzed in monocular mode, where each detector is treated separately, or in stereoscopic mode where they are considered together.
TL;DR: In this article, a hyperlens can be used for photolithography to generate deep subwavelength arbitrary patterns from diffraction-limited masks, which can be extended from cylindrical interfaces to arbitrary interfaces.
Abstract: We propose that a hyperlens can be used for photolithography to generate deep subwavelength arbitrary patterns from diffraction-limited masks. Numerical simulation shows that half-pitch resolution down to 20 nm is possible from a mask with 280 nm period at working wavelength 375 nm. We also extend the hyperlens projection concept from cylindrical interfaces to arbitrary interfaces. An example of a flat interface hyperlens is numerically demonstrated for lithography purposes.
TL;DR: The proposed waveguiding system inherently has no cutoff for any core width and height, paving the way toward the deep subwavelength transport of THz waves for integrated THz device applications.
Abstract: We propose a novel subwavelength terahertz (THz) waveguide based on the magnetic plasmon polariton mode guided by a narrow gap in a negative permeability metamaterial. Deep subwavelength waveguiding (
TL;DR: In this paper, the interaction between residual stress and fatigue crack growth rate has been investigated in middle tension and compact tension specimens machined from a variable polarity plasma arc welded aluminium alloy 2024-T351 plate.
TL;DR: In this paper, a simple and efficient method is presented for predicting fatigue crack growth rate in welded butt joints, based on the superposition rule of the linear elastic fracture mechanics, welding residual stress effect is accounted for by replacing the nominal stress ratio (R ) in the empirical laws by the effective stress intensity factor ratio ( R eff ).
TL;DR: A new class of nanoscale plasmonic sources based on subwavelength dielectric cavities embedded in a metal slab based on strong dispersion near the Fabry-Perot resonance is presented and the phase and amplitude of the generated plasmons are controlled at the subwa wavelength scale.
Abstract: We present a new class of nanoscale plasmonic sources based on subwavelength dielectric cavities embedded in a metal slab. Exploiting the strong dispersion near the Fabry−Perot resonance in such a resonator, we control the phase and the amplitude of the generated plasmons at the subwavelength scale. As an example, we present a subwavelength unidirectional plasmonic antenna utilizing interference between two plasmonic cavity sources with matched phase and amplitude.
TL;DR: In this paper, a review of recent developments in magnetic plasmonics arising from the coupling effect in metamaterials is given, where it is shown that the coupling between these units produces multiple discrete resonance modes due to hybridization.
Abstract: Magnetic metamaterials consist of magnetic resonators smaller in size than their excitation wavelengths. Their unique electromagnetic properties were characterized by the effective media theory at the early stage. However, the effective media model does not take into account the interactions between magnetic elements; thus, the effective properties of bulk metamaterials are the result of the “averaged effect” of many uncoupled resonators. In recent years, it has been shown that the interaction between magnetic resonators could lead to some novel phenomena and interesting applications that do not exist in conventional uncoupled metamaterials. In this paper, we will give a review of recent developments in magnetic plasmonics arising from the coupling effect in metamaterials. For the system composed of several identical magnetic resonators, the coupling between these units produces multiple discrete resonance modes due to hybridization. In the case of a system comprising an infinite number of magnetic elements, these multiple discrete resonances can be extended to form a continuous frequency band by strong coupling. This kind of broadband and tunable magnetic metamaterial may have interesting applications. Many novel metamaterials and nanophotonic devices could be developed from coupled resonator systems in the future. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the effectiveness of crack growth retarders bonded to integral metallic structures was investigated by both numerical modelling and experimental tests, and the authors concluded that by bonding discrete straps to an integral structure, the fatigue crack growth life can be significantly improved.
TL;DR: This work experimentally demonstrates plasmonic interference patterns that can be designed at will by shaping the edges in a metallic film that will have profound potentials in nanolithography, particle manipulation, and other related fields.
Abstract: A plasmonic interference pattern can be formed when multiple surface plasmon waves overlap coherently. Utilizing a sharp edge coupling mechanism, we experimentally demonstrate plasmonic interference patterns that can be designed at will by shaping the edges in a metallic film. The patterns can also be dynamically tailored by adjusting the wavelength, the polarization, and the incident angle of the excitation light beam. Possessing the subdiffraction limited feature resolution, this dynamical manipulation method of surface plasmon patterns will have profound potentials in nanolithography, particle manipulation, and other related fields.
TL;DR: The optical response of fishnet metamaterial can be modulated in femtosecond time scale, but the modulation magnitude is greatly enhanced through the plasmon resonance.
Abstract: We show by pump-probe spectroscopy that the optical response of a fishnet metamaterial can be modulated on the femtosecond time scale. The modulation dynamics is dominated by pump-induced changes in the constituting dielectric medium, but the strength of modulation is dramatically enhanced through the plasmon resonance. The pump-induced spectral responses of the metamaterial provide understanding on how the resonance is modified by pump excitation. Our study suggests that metamaterials can be used as high-speed amplitude/phase modulators with terahertz-bandwidth.