Showing papers by "Philips published in 2004"

Inkjet Printing of Polymers: State of the Art and Future Developments

Abstract: Inkjet printing is considered to be a key technology in the field of defined polymer deposition. This article provides an introduction to inkjet printing technology and a short overview of the available instrumentation. Examples of polymer inkjet printing are given, including the manufacturing of multicolor polymer light-emitting diode displays, polymer electronics, three-dimensional printing, and oral dosage forms for controlled drug release. Special emphasis is placed upon the utilized polymers and conditions, such as polymer structure, molar mass, solvents, and concentration. Studies on viscoelastic fluid jets and the formation of viscoelastic droplets under gravity indicate that strain hardening is the key parameter that determines the inkjet printability of polymer solutions.

Flexible active-matrix displays and shift registers based on solution-processed organic transistors.

Abstract: At present, flexible displays are an important focus of research1,2,3 Further development of large, flexible displays requires a cost-effective manufacturing process for the active-matrix backplane, which contains one transistor per pixel One way to further reduce costs is to integrate (part of) the display drive circuitry, such as row shift registers, directly on the display substrate Here, we demonstrate flexible active-matrix monochrome electrophoretic displays based on solution-processed organic transistors on 25-μm-thick polyimide substrates The displays can be bent to a radius of 1 cm without significant loss in performance Using the same process flow we prepared row shift registers With 1,888 transistors, these are the largest organic integrated circuits reported to date More importantly, the operating frequency of 5 kHz is sufficiently high to allow integration with the display operating at video speed This work therefore represents a major step towards 'system-on-plastic'

Quantum Transport in Semiconductor Nanostructures

Abstract: I. Introduction (Preface, Nanostructures in Si Inversion Layers, Nanostructures in GaAs-AlGaAs Heterostructures, Basic Properties). II. Diffusive and Quasi-Ballistic Transport (Classical Size Effects, Weak Localization, Conductance Fluctuations, Aharonov-Bohm Effect, Electron-Electron Interactions, Quantum Size Effects, Periodic Potential). III. Ballistic Transport (Conduction as a Transmission Problem, Quantum Point Contacts, Coherent Electron Focusing, Collimation, Junction Scattering, Tunneling). IV. Adiabatic Transport (Edge Channels and the Quantum Hall Effect, Selective Population and Detection of Edge Channels, Fractional Quantum Hall Effect, Aharonov-Bohm Effect in Strong Magnetic Fields, Magnetically Induced Band Structure).

Gate Insulators in Organic Field-Effect Transistors

Abstract: In this paper, we review recent progress in the understanding of insulator/semiconductor interfaces in organic field-effect transistors (OFETs). We would like to emphasize that the choice of gate insulator is as important for high-quality OFET devices as the semiconductor itself, especially because of the unique transport mechanisms operating in them. To date researchers have explored numerous organic and inorganic insulator materials, some of them designed to improve the morphology of the organic semiconductor (OSC). Surface treatments, particularly on inorganic insulators, have been shown to influence significantly molecular ordering and device performance. In addition, the deposition technique used for the insulator and semiconductor layers has a further impact on the active interface. Dielectric related effects are reviewed here for a variety of polymeric and molecular semiconductors reported in the literature, with an emphasis on electronic transport. We also review in more detail experiences at Phil...

Compositions that can produce polymers

Abstract: This invention provides a compositions that are useful for polymerizing at least one monomer into at least one polymer.

Carbazole Compounds as Host Materials for Triplet Emitters in Organic Light-Emitting Diodes: Tuning the HOMO Level without Influencing the Triplet Energy in Small Molecules

Abstract: A series of novel carbazole compounds was synthesized and tested for their suitability as host for triplet emitters in an organic-light emitting diode (OLED). In these compounds, a carbazole unit is either connected to other carbazole units to form carbazole dimers and trimers or to fluorene and oxadiazole derivatives to form mixed compounds. The HOMO level of carbazole compounds can be tuned by substitution at the 3, 6, and/or 9 positions. Making oligomers by connecting carbazole molecules via their 3 (3′) positions shifts the HOMO level to higher energy, while replacing alkyl groups at the 9 (9′) positions by aryl groups shifts the HOMO level to lower energy. Furthermore, it has been found that the triplet energy of these compounds is determined by the presence of poly(p-phenyl) chains in the molecular structure. By identifying the longest poly(p-phenyl) chain, one can predict whether a compound will be a suitable host for a high-energy triplet emitter. An overview of HOMO levels, singlet and triplet levels, and exchange energies is given for all carbazole compounds synthesized. Finally, OLEDs employing two selected carbazole compounds as host and fac-tris(2-phenylpyridine)-iridium (Ir(ppy) 3) as guest were constructed and characterized electrically.

Relating the morphology of poly(p-phenylene vinylene)/methanofullerene blends to solar-cell performance

Abstract: The performance of bulk-heterojunction solar cells based on a phase-separated mixture of donor and acceptor materials is known to be critically dependent on the morphology of the active layer. Here we use a combination of techniques to resolve the morphology of spin cast films of poly(p-phenylene vinylene)/methanofullerene blends in three dimensions on a nanometer scale and relate the results to the performance of the corresponding solar cells. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and depth profiling using dynamic time-of-flight secondary ion mass spectrometry (TOF-SIMS) clearly show that for the two materials used in this study, 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM) and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV), phase separation is not observed up to 50 wt.-% PCBM. Nanoscale phase separation throughout the film sets in for concentrations of more than 67 wt.-% PCBM, to give domains of rather pure PCBM in a homogenous matrix of 50:50 wt.-% MDMO-PPV/PCBM. Electrical characterization, under illumination and in the dark, of the corresponding photovoltaic devices revealed a strong increase of power conversion efficiency when the phase-separated network develops, with a sharp increase of the photocurrent and fill factor between 50 and 67 wt.-% PCBM. As the phase separation sets in, enhanced electron transport and a reduction of bimolecular charge recombination provide the conditions for improved performance. The results are interpreted in terms of a model that proposes a hierarchical build up of two cooperative interpenetrating networks at different length scales.

Spatially correlated charge transport in organic thin film transistors

Abstract: Hole mobility in organic ultrathin film field-effect transistors is studied as a function of the coverage. For layered sexithienyl films, the charge carrier mobility rapidly increases with increasing coverage and saturates at a coverage of about two monolayers. This shows that the first two molecular layers next to the dielectric interface dominate the charge transport. A quantitative analysis of spatial correlations shows that the second layer is crucial, as it provides efficient percolation pathways for carriers generated in both the first and the second layers. The upper layers do not actively contribute either because their domains are smaller than the ones in the second layer or because the carrier density is negligible.

Thermal management methods and apparatus for lighting devices

Abstract: Methods and systems are provided for providing active and passive thermal or cooling facilities for LED lighting systems, including radiating and convective thermal facilities, including fans, phase change materials, conductive polymers, potting compounds, vents, ducts, and other thermal facilities.

The spindle checkpoint, aneuploidy, and cancer

Abstract: Cancer cells contain abnormal number of chromosomes (aneuploidy), which is a prevalent form of genetic instability in human cancers. Defects in a cell cycle surveillance mechanism called the spindle checkpoint contribute to chromosome instability and aneuploidy. In response to straying chromosomes in mitosis, the spindle checkpoint inhibits the ubiquitin ligase activity of the anaphase-promoting complex or cyclosome (APC/C), thus preventing precocious chromosome segregation and ensuring the accurate partition of the genetic material. We review recent progress toward the understanding of the molecular mechanism of the spindle checkpoint and its role in guarding genome integrity at the chromosome level.

Tile lighting methods and systems

Abstract: A tile lighting system is provided in which an interior space of a tile is lit by LEDs, such as in a grid or edge-lit formation, and a light diffusing panel is disposed over the interior space. The tile lighting system can be combined with others to tile any surface, such as a floor, ceiling, wall, or building exterior. Lighting control signals can be supplied to generate a wide range of effects on the tile lighting units, including effects coordinated among different tile lighting units. Two- and three-dimensional embodiments are contemplated.

Acquiring 4D thoracic CT scans using a multislice helical method

Abstract: Respiratory motion degrades anatomic position reproducibility during imaging, necessitates larger margins during radiotherapy planning and causes errors during radiation delivery. Computed tomography (CT) scans acquired synchronously with the respiratory signal can be used to reconstruct 4D CT scans, which can be employed for 4D treatment planning to explicitly account for respiratory motion. The aim of this research was to develop, test and clinically implement a method to acquire 4D thoracic CT scans using a multislice helical method. A commercial position-monitoring system used for respiratory-gated radiotherapy was interfaced with a third generation multislice scanner. 4D cardiac reconstruction methods were modified to allow 4D thoracic CT acquisition. The technique was tested on a phantom under different conditions: stationary, periodic motion and non-periodic motion. 4D CT was also implemented for a lung cancer patient with audio-visual breathing coaching. For all cases, 4D CT images were successfully acquired from eight discrete breathing phases, however, some limitations of the system in terms of respiration reproducibility and breathing period relative to scanner settings were evident. Lung mass for the 4D CT patient scan was reproducible to within 2.1% over the eight phases, though the lung volume changed by 20% between end inspiration and end expiration (870 cm3). 4D CT can be used for 4D radiotherapy, respiration-gated radiotherapy, 'slow' CT acquisition and tumour motion studies.

Methods and apparatus for controlling illumination

Abstract: Methods and apparatus for controlling illumination. In one example, one or more multi-color light sources are controlled based on one or more interruptions of power supplied to the light source(s). In another example, a pool or spa is illuminated by one or more multi-color light sources that may be employed as individually and independently controllable devices that may be controlled based on one or more interruptions in power. In another example, the selection of a particular illumination program for such light sources (e.g., by one or more interruptions in power) is indicated to a user via the radiation generated by the light sources.

Experimental study of the impact of an ink-jet printed droplet on a solid substrate

Abstract: This paper reports on an experimental study of the impact of water droplets on a solid substrate, with a droplet radius between 18 and 42 μm. We optically measured the interface shape during impact. The measured impact sequences show the impact phenomenology, droplet radius as a function of time, and oscillation behavior in the later stages of impact. The measured radius during impact is compared with existing models, and some of the deficiencies of common models are shown. The measured oscillation frequency in the later stage of impact compares well with an available analytical model. In addition, we measured the volume of the small bubble, which forms in the initial impact stage, as a function of impact velocity. The measured volume compares reasonably well with an approximate model based on air entrapment.

Method for configuring and routing data within a wireless multihop network and a wireless network for implementing the same

Abstract: A method for configuring a wireless data packet network comprising a control node and multiple individual nodes includes the following steps: organizing the network into multiple bands Bi each band including individual nodes located i hops away from the control node; assigning a logical address to each individual node. A routing logical address is added to every data packet and each individual node compares its own logical address to the routing address of a received packet. In dependence on the result of the comparison, the packet is discarded, re-transmitted or processed in the node. The network is preferably a packet-hopping wireless network in which data packets are transferred from node to node over a common RF channel.

Social Reproduction and Child-rearing Practices: Social Class, Children's Agency, and the Summer Activity Gap

Abstract: This study contributes to the ongoing scholarly debate about the relative importance of parents' resources and values in influencing parents' child-rearing practices. Using ethnographic data on children's summer experiences, the authors examine how families from different ethnic and social-class backgrounds assemble child care and other activities for their children during summer vacation. The authors argue that social-class differences in the quality and quantity of children's activities do not stem largely from fundamental differences in parents' desires to help children develop or cultivate their skills and talents. Instead, these differences stem from parents' differential access to a wide range of resources, including money, the human capital to know how best to assess and improve children's skills, the cultural capital to know how best to cultivate children's talents, and the social capital to learn about and gain access to programs and activities. The authors also show that children's own values an...

System for ad hoc sharing of content items between portable devices and interaction methods therefor

Abstract: A user interface concept for wireless ad hoc content sharing between portable devices referred to as portable content containers (PCCs). A user-centered design approach is provided enabling users to share content such as music and photos. A variety of physical ways of establishing a secure connections between the PCC devices is provided. In addition, a clear view on the location of the content stored on the devices, and a drag & drop interface is provided. Use is made of separate spaces, each containing the corresponding content and includes a 'shared' space such that all connected users may transfer content to and from to their own personal devices. The use of a drag & drop interface in combination with the subdivision of the screen into several spaces, provided the user with a clear view on the content location. The close proximity of users is assumed and enhances social interaction.

Cardiac SSFP imaging at 3 Tesla

Abstract: Balanced steady-state free precession (SSFP) techniques provide excellent contrast between myocardium and blood at a high signal-to-noise ratio (SNR). Hence, SSFP imaging has become the method of choice for assessing cardiac function at 1.5T. The expected improvement in SNR at higher field strength prompted us to implement SSFP at 3.0T. In this work, an optimized sequence protocol for cardiac SSFP imaging at 3.0T is derived, taking into account several partly adverse effects at higher field, such as increased field inhomogeneities, longer T1, and power deposition limitations. SSFP contrast is established by optimizing the maximum amplitude of the radiofrequency (RF) field strength for shortest TR, as well as by localized linear or second-order shimming and local optimization of the resonance frequency. Given the increased SNR, sensitivity encoding (SENSE) can be employed to shorten breath-hold times. Short-axis, long-axis, and four-chamber cine views obtained in healthy adult subjects are presented, and three different types of artifacts are discussed along with potential methods for reducing them. Magn Reson Med 51:799–806, 2004. © 2004 Wiley-Liss, Inc.

Managing digital identity information

Abstract: A basic architecture for managing digital identity information in a network such as the World Wide Web is provided. A user of the architecture can organize his or her information into one or more profiles which reflect the nature of different relationships between the user and other entities, and grant or deny each entity access to a given profile. Various enhancements which may be provided through the architecture are also described, including tools for filtering email, controlling access to user web pages, locating other users and making one's own location known, browsing or mailing anonymously, filling in web forms automatically with information already provided once by hand, logging in automatically, securely logging in to multiple sites with a single password and doing so from any machine on the network, and other enhancements.

Light system manager

Abstract: Methods and systems are provided for lighting control, including a lighting system manager, a light show composer, a light system engine, and related facilities for the convenient authoring and execution of lighting shows using semiconductor-based illumination units.

Targeted nanoparticles for quantitative imaging of sparse molecular epitopes with MRI

Abstract: Before molecular imaging with MRI can be applied clinically, certain problems, such as the potential sparseness of molecular epitopes on targeted cell surfaces, and the relative weakness of conventional targeted MR contrast agents, must be overcome. Accordingly, the conditions for diagnostic conspicuity that apply to any paramagnetic MRI contrast agent with known intrinsic relaxivity were examined in this study. A highly potent paramagnetic liquid perfluorocarbon nanoparticle contrast agent ( approximately 250 nm diameter, >90,000 Gd3+/particle) was imaged at 1.5 T and used to successfully predict a range of sparse concentrations in experimental phantoms with the use of standard MR signal models. Additionally, we cultured and targeted the smooth muscle cell (SMC) monolayers that express "tissue factor," a glycoprotein of crucial significance to hemostasis and response to vascular injury, by conjugating an anti-tissue factor antibody fragment to the nanoparticles to effect specific binding. Quantification of the signal from cell monolayers imaged at 1.5 T demonstrated, as predicted via modeling, that only picomolar concentrations of paramagnetic perfluorocarbon nanoparticles were required for the detection and quantification of tissue factor at clinical field strengths. Thus, for targeted paramagnetic agents carrying high payloads of gadolinium, it is possible to quantify molecular epitopes present in picomolar concentrations in single cells with routine MRI.

Carbon nanotube electron sources and applications

Abstract: In this review we give an overview of the present status of research on carbon nanotube (CNT) field emitters and their applications. Several different construction principles of field-emission devices with CNTs are summarized. The emission mechanism is introduced and a detailed overview is given of the measured emission properties and related topics of CNT electron sources. We give also several examples of field-emission devices with CNT electron emitters that are presently being investigated in the academic world as well as in industry. Carbon nanotube electron sources clearly have interesting properties, such as low voltage operation, good stability, long lifetime and high brightness. The most promising applications are the field-emission display and high-resolution electron-beam instruments. But several hurdles remain, such as the manufacture of an electron source or an array of electron sources with exactly the desired properties in a reproducible manner.

Development of piezoelectric micromachined ultrasonic transducers

Abstract: Piezoelectric micromachined ultrasonic transducers (pMUTs) are an example of the application of MEMS technology to ultrasound generation and detection, which is expected to offer many advantages over conventional transducers. In this work, we investigate pMUTs through novel design and fabrication methods. A finite element (FE) model, with original tools to measure device performance, was developed to design and optimize pMUTs. A pMUT for the operating range of 2–10 MHz in water and having maximized energy coupling coefficient was modeled, designed, fabricated, and tested for its resonance frequency and coupling coefficient. The model predictions for the resonance frequency were in excellent agreement with the measured values, but not as good for the coupling coefficient due to the variability in the measured coupling coefficient. Compared to conventional ultrasonic transducers, pMUTs exhibit superior bandwidth, in excess of 100%, and offer considerable design flexibility, which allows their operation frequency and acoustic impedance to be tailored for numerous applications.

Remote wavelength conversion in an illumination device

Abstract: An illumination device uses a wavelength converting element, such as a phosphor layer, that is physically separated from a light source, such as one or more light emitting diodes, a Xenon lamp or a Mercury lamp The wavelength converting element is optically separated from the light source, so that the converted light emitted by the wavelength converting element is prevented from being incident on the light source Accordingly, the temperature limitations of the wavelength converting element are removed, thereby permitting the light source to be driven with an increased current to produce a higher radiance Moreover, by optically separating the wavelength converting element from the light source, the conversion and recycling efficiency of the device is improved, which also increases radiance

Human Bub1 protects centromeric sister-chromatid cohesion through Shugoshin during mitosis

Abstract: Sister chromatids in mammalian cells remain attached mostly at their centromeres at metaphase because of the loss of cohesion along chromosome arms in prophase. Here, we report that Bub1 retains centromeric cohesion in mitosis of human cells. Depletion of Bub1 or Shugoshin (Sgo1) in HeLa cells by RNA interference causes massive missegregation of sister chromatids that originates at centromeres. Surprisingly, loss of chromatid cohesion in Bub1 and Sgo1 RNA-interference cells does not appear to require the full activation of separase but, instead, triggers a mitotic arrest that depends on Mad2 and Aurora B. Bub1 maintains the steady-state levels and centromeric localization of Sgo1. Therefore, Bub1 protects centromeric cohesion through Shugoshin in mitosis.

Characterization of age-related effects in human skin: A comparative study that applies confocal laser scanning microscopy and optical coherence tomography.

Abstract: Skin structure and age-related changes in human skin were characterized in vivo by applying confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT). The overall effect of aging skin, derived from studies of volunteers belonging to two age groups, was found to be a significant decrease in the maximum thickness of the epidermis and flattening of the dermo-epidermal junction. At a certain depth in the dermis, well below the basal layer, a reflecting layer of fibrous structure is observed in CLSM images. The location of this layer strongly depends on age and is situated much deeper below the skin surface in younger than in older skin. In addition, large structural changes were observed with age. The OCT images show two bright reflecting layers. The first one is due to scattering at the skin surface. The second band appears to be caused by a layer of fibrous structure in the dermis. Direct comparison of CLSM and OCT suggests that the same fibrous layer is imaged by the two techniques. This layer might be due to the transition between the papillary and reticular dermis. A comparison of CLSM and OCT enables a better understanding of the images.