用于单芯片系统的改进型WXGA LCoS成像器

本文讨论用于单芯片时序混色的菲利浦DD-720硅基液晶(LCoS)片。这种芯片主要用于HDTV背投影机和多媒体系统。与菲利浦以前的单片LCoS设计相比，由于该芯片具有电接口接点较少、封装简单和温度传感器内置等许多特点，使其应用于投影系统时成本降低。     

Optimization of black oxide coating thickness as an adhesion promoter for copper substrate in plastic integrated-circuit packages

Copper-oxide coating applied onto the copper substrate has emerged as an alternative to metallic coatings to improve adhesion with polymeric adhesives and molding compounds. The interfacial-bond strengths between the black oxide-coated Cu substrate and epoxy-based, glob-top resin were measured in button-shear tests, and the failure mechanisms were identified from the fracture-surface examination. The emphasis was to establish the correlation between the coating thickness, the surface roughness, and the interfacial adhesion with respect to treatment time. It was found that at the initial stage of treatment a thin layer of flat, cuprous oxide developed, above which fibrillar-cupric oxide was formed with further treatment until saturation with densified fibrils at about 150 sec. The interfacial-bond strength between the oxide-coated copper substrate and glob-top resin increased gradually with increasing treatment time, until the bond strength reached a plateau constant after a treatment for about 150 sec. There was a functional similarity between the oxide thickness, the surface roughness, and the interface-bond strength with respect to treatment time. A treatment time of 150 sec is considered an optimal condition that can impart the highest interface adhesion.     

Shear elastic modulus estimation from indentation and SDUV on gelatin phantoms

Tissue mechanical properties such as elasticity are linked to tissue pathology state. Several groups have proposed shear wave propagation speed to quantify tissue mechanical properties. It is well known that biological tissues are viscoelastic materials; therefore, velocity dispersion resulting from material viscoelasticity is expected. A method called shearwave dispersion ultrasound vibrometry (SDUV) can be used to quantify tissue viscoelasticity by measuring dispersion of shear wave propagation speed. However, there is not a gold standard method for validation. In this study, we present an independent validation method of shear elastic modulus estimation by SDUV in three gelatin phantoms of differing stiffness. In addition, the indentation measurements are compared to estimates of elasticity derived from shear wave group velocities. The shear elastic moduli from indentation were 1.16, 3.40, and 5.6 kPa for a 7%, 10%, and 15% gelatin phantom, respectively. SDUV measurements were 1.61, 3.57, and 5.37 kPa for the gelatin phantoms, respectively. Shear elastic moduli derived from shear wave group velocities were 1.78, 5.2, and 7.18 kPa for the gelatin phantoms, respectively. The shear elastic modulus estimated from the SDUV, matched the elastic modulus measured by indentation. On the other hand, shear elastic modulus estimated by group velocity did not agree with indentation test estimations. These results suggest that shear elastic modulus estimation by group velocity will be bias when the medium being investigated is dispersive. Therefore, a rheological model should be used in order to estimate mechanical properties of viscoelastic materials.     

Insulator‐Conductor Type Transitions in Graphene‐Modified Silver Nanowire Networks: A Route to Inexpensive Transparent Conductors

Silver nanowire coatings are an attractive alternative to indium tin oxide for producing transparent conductors. To fabricate coatings with low sheet resistance required for touchscreen displays, a multi‐layer network of silver nanowires must be produced that may not be cost effective. This problem is counteracted here by modifying the electrical properties of an ultra‐low‐density nanowire network through local deposition of conducting graphene platelets. Unlike other solution‐processed materials, such as graphene oxide, our pristine graphene is free of oxygen functional groups, resulting in it being electrically conducting without the need for further chemical treatment. Graphene adsorption at inter‐wire junctions as well as graphene connecting adjacent wires contributes to a marked enhancement in electrical properties. Using our approach, the amount of nanowires needed to produce viable transparent electrodes could be more than 50 times less than the equivalent pristine high density nanowire networks, thus having major commercial implications. Using a laser ablation process, it is shown that the resulting films can be patterned into individual electrode structures, which is a pre‐requisite to touchscreen sensor fabrication.     

Hydrogen-bonded diketopyrrolopyrrole (DPP) pigments as organic semiconductors

Diketopyrrolopyrroles (DPPs) have recently gained attention as building-blocks for organic semiconducting polymers and small molecules, however the semiconducting properties of their hydrogen-bonded (H-bonded) pigment forms have not been explored. Herein we report on the performance of three archetypical H-bonded DPP pigments, which show ambipolar carrier mobilities in the range 0.01–0.06 cm²/V s in organic field-effect transistors. Their semiconducting properties are correlated with crystal structure, where an H-bonded crystal lattice supports close and relatively cofacial π–π stacking. To better understand transport in these systems, density functional theory calculations were carried out, indicating theoretical maximum ambipolar mobility values of ∼0.3 cm²/V s. Based on these experimental and theoretical results, H-bonded DPPs represent a viable alternative to more established DPP-containing polymers and small molecules where H-bonding is blocked by N-alkylation.     

Nanoimprint lithography fabrication of waveguide-integrated optical gratings with inexpensive stamps

We demonstrate that a replica grating can be effectively used as an inexpensive stamp for nanoimprint lithography to pattern diffractive optical couplers integrated with planar optical waveguides. Imprinted grating patterns were integrated with silicon oxynitride waveguide films to be used as an evanescent wave sensor in the input grating-coupler configuration. An anti-adhesion layer using an inexpensive, two-step chemical functionalization was developed for the stamps. The stamps were able to withstand imprint temperatures ranging from 140 to 190 °C and high fidelity imprints were obtained. The groove pattern was integrated in waveguide films by etch transfer and light-coupling properties of gratings with 1.2 μm pitch were tested using a λ = 1.55 μm laser. Compared to etched silicon masters, replica optical gratings provide uniform pattern density over their entire surface with no unstructured regions, are inexpensive, and readily available for R&D use.     

Explaining the Formation of Online News Startups in France and the United States: A Field Analysis

This article examines the differential formation of online news startups in Toulouse, France, and Seattle, United States. While Seattle is home to many startups, in Toulouse there have been just 4—and only 1 continues publishing. Drawing on Bourdieu's field theory, we argue that amount and types of capital held by journalists in the 2 cities varied as a result of differences in journalism's position in the field of power. These differences shaped the extent of startup formation in each city and structured journalists' capacities to convert their capital into the resources needed to form startups (e.g., funding, credentials, partnerships). These findings are positioned in relation to literatures on journalism innovation and comparative media.     

Photoresponsive Fiber Array: Toward Mimicking the Collective Motion of Cilia for Transport Applications

Remote transport of material is an utmost useful, but challenging, property expanding the design possibilities of many applications such as microfluidics or robotics where species can be carried without interfering with its environment. Nature has solved the problem of transport in e.g., the respiratory system by a concerted motion of cilia. This study addresses a new method to fabricate an array of small parallel fibers acting as cilia placed side by side on a substrate. The fibers consist of a crosslinked liquid crystal main chain polymer functionalized with coreactant azobenzene molecules. The fibers bend toward a light source in a concerted manner. When placed in a liquid, the cooperative bending motion of the fibers creates a flow able to efficiently carry objects. The proposed fabrication process of the fibers is scalable to large area and requires an optimized rheology which is achieved by converting low molecular weight reactive liquid crystal acrylate monomers to oligomers using a multiplication of the monomeric units by the Michael addition reaction with dithiol. The oligomer properties and the elasticity of the fibers are adjusted by changing the thiol spacer leading to optimized manufacturing and maximized optical response.     

Gas Pickering Emulsion Templated Hollow Carbon for High Rate Performance Lithium Sulfur Batteries

A CO₂ in water nanoparticle stabilized Pickering emulsion is used to template micrometer sized hollow porous nitrogen doped carbon particles for high rate performance lithium sulfur battery. For the first time, nanoparticles serve the dual role of an emulsion stabilizer and a pore template for the shell, directly utilizing in situ generated CO₂ bubbles as template for the core. The minimalistic nature of this method does not require expensive surfactants or additional core templates. Upon polymerization of melamine formaldehyde onto CO₂, a robust polymer/silica composite shell is formed and transformed into a porous shell upon washing. The micrometer‐sized hollow morphology in combination with its nitrogen rich porous shell demonstrates impressive rate capabilities of 670 and 500 mAh g^?1 even at a high rate of 7C and 9C, respectively. This material also possesses excellent cycle durability, exhibiting a low capacity decay of 0.088%/cycle over 300 cycles. Measurement of the shuttle current and impedance provides interesting insight into the polysulfide mass transfer mechanism of hollow structured sulfur hosts.