超低失真多层陶瓷电容相较于薄膜电容的优势

在滤波应用中,超低失真的表面贴装多层陶瓷电容(MLCC),已经成为模拟电路设计者在SMD塑料薄膜(薄膜片式)电容之外的另一种选择,它的体积更小、成本更低、也更为可靠。这些潜在的模拟电路应用实例包括:音响设备、无线设备、锁相环(PLL)和通信设备(如调制/解调器)等。这些新型电容的等效串连电阻(ESR)极低,因此非常适合于高效率的DC/DC变换器和高速微处理器应用。低失真电容的应用随着处理器速度的提高和工作电压的降低,噪声会给信号完整性带来严重的影响,除非能通过过滤或解耦的办法将其去除。在声频、射频、PLL和通信电路中,跟踪误差…     

Acrylic nonaqueous dispersion using butylated melamine-formaldehyde resin as dispersant

A series of acrylic nonaqueous dispersions were prepared by using various kinds of butylated melamine–formaldehyde (BMF) resins as dispersant. The functional group composition of BMF to form stable dispersion was butoxy group more than 13 mol/BMF 1 mol, and methylol group ranged from 1 to 2.5 mol/BMF 1 mol. It is concluded that the anchoring of BMF to acrylic copolymer was due to the formation of covalent bond between methylol group in BMF and hydroxy group in acrylic copolymer.     

Behavioral and electroantennogram responses of periplanone analogs

The biological activities of synthetic periplanone analogs, including four candidates of periplanone-A (P-A), were evaluated by behavioral and electroantennogram (EAG) assays. Among 16 periplanone analogs, six compounds evoked pheromonal activity from the male American cockroaches. The threshold dosages of these biological active analogs were 10–10⁵ times lower than that of the known periplanone mimic, germacrene-D. The conformation required for eliciting the pheromonal activity is discussed in terms of the structure-activity relationship of these analogs. Hauptmann's P-A elicited the strongest pheromonal activity among four candidates of P-A in our bioassay, suggesting that Hauptmann's P-A is a natural P-A produced from female cockroaches.     

The role of pressure on thin amorphous carbon films deposited using microwave surface wave plasma CVD

We report the effects of gas composition pressure (GCP) on the optical, structural and electrical properties of thin amorphous carbon (a-C) films grown on p-type silicon and quartz substrates by microwave surface wave plasma chemical vapor deposition (MW SWP CVD). The films, deposited at various GCPs ranging from 50 to 110 Pa, were studied by UV/VIS/NIR spectroscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and current–voltage characteristics. The optical band gap of the a-C film was tailored to a relatively high range, 2.3–2.6 eV by manipulating GCPs from 50 to 110 Pa. Also, spin density strongly depended on the band gap of the a-C films. Raman spectra showed qualitative structured changes due to sp³/sp² carbon bonding network. The surfaces of the films are found to be very smooth and uniform (RMS roughness < 0.5 nm). The photovoltaic measurements under light illumination (AM 1.5, 100 mW/cm²) show that short-circuit current density, open-circuit voltage, fill factor and photo-conversion efficiency of the film deposited at 50 Pa were 6.4 μA/cm², 126 mV, 0.164 and 1.4 × 10^− 4% respectively.     

Nitrogen incorporated diamond-like carbon films by microwave surface wave plasma CVD

Nitrogen incorporated diamond like carbon films have been deposited by microwave surface wave plasma chemical vapor deposition (MW-SWP-CVD), using methane (CH₄) as the source of carbon and with different nitrogen flow rates (N₂ / CH₄ flow ratios between 0 and 3). The influence of the nitrogen incorporation on the optical, structural properties and surface morphology of the carbon films were investigated using different spectroscopic techniques. The nitrogen has been incorporated into DLC:N films which was confirmed by the X-ray photoelectron spectroscopy (XPS) measurement. Moreover, the nitrogen incorporation was accompanied by a variation in the optical gap, which was attributed to the removal or creation of band tail states.     

Diamond-like carbon thin films by microwave surface-wave plasma CVD aimed for the application of photovoltaic solar cells

The nitrogen doped diamond-like carbon (DLC) thin films were deposited on quartz and silicon substrates by a newly developed microwave surface-wave plasma chemical vapor deposition, aiming the application of the films for photovoltaic solar cells. For film deposition, we used argon as carrier gas, nitrogen as dopant and hydrocarbon source gases, such as camphor (C₁₀H₁₆O) dissolved with ethyl alcohol (C₂H₅OH), methane (CH₄), ethylene (C₂H₄) and acetylene (C₂H₂). The optical and electrical properties of the films were studied using X-ray photoelectron spectroscopy, Nanopics 2100/NPX200 surface profiler, UV/VIS/NIR spectroscopy, atomic force microscope, electrical conductivity and solar simulator measurements. The optical band gap of the films has been lowered from 3.1 to 2.4 eV by nitrogen doping, and from 2.65 to 1.9 eV by experimenting with different hydrocarbon source gases. The nitrogen doped (flow rate: 5 sccm; atomic fraction: 5.16%) film shows semiconducting properties in dark (i.e. 8.1 × 10^{− 4} Ω^{− 1} cm^{− 1}) and under the light illumination (i.e. 9.9 × 10^{− 4} Ω^{− 1} cm^{− 1}). The surface morphology of the both undoped and nitrogen doped films are found to be very smooth (RMS roughness ≤ 0.5 nm). The preliminary investigation on photovoltaic properties of DLC (nitrogen doped)/p-Si structure show that open-circuit voltage of 223 mV and short-circuit current density of 8.3 × 10^{− 3} mA/cm². The power conversion efficiency and fill factor of this structure were found to be 3.6 × 10^{− 4}% and 17.9%, respectively. The use of DLC in photovoltaic solar cells is still in its infancy due to the complicated microstructure of carbon bondings, high defect density, low photoconductivity and difficulties in controlling conduction type. Our research work is in progress to realize cheap, reasonably high efficiency and environmental friendly DLC-based photovoltaic solar cells in the future.     

Synthesis of nitrogen incorporated diamond-like carbon thin films using microwave surface-wave plasma CVD

Nitrogenated diamond-like (DLC:N) carbon thin films have been deposited by microwave surface wave plasma chemical vapor deposition on silicon and quartz substrates, using argon gas, camphor dissolved in ethyl alcohol composition and nitrogen as plasma source. The deposited DLC:N films were characterized for their chemical, optical, structural and electrical properties through X-ray photoelectron spectroscopy, UV/VIS/NIR spectroscopy, Raman spectroscopy, atomic force microscope and current–voltage characteristics. Optical band gap decreased (2.7 to 2.4 eV) with increasing Ar gas flow rate. The photovoltaic measurements of DLC:N / p-Si structure show that the open-circuit voltage (V_oc) of 168.8 mV and a short-circuit current density (J_sc) of 8.4 μA/cm² under light illumination (AM 1.5 100 mW/cm²). The energy conversion efficiency and fill factor were found to be 3.4 × 10^{− 4}% and 0.238 respectively.     

Repeatedly foldable AMOLED display

In this study, a 5.9‐inch foldable active‐matrix organic light emitting diode (AMOLED) display was developed. A folding test was performed repeatedly. The display survived the folding test (100,000 folds) with a curvature radius of 2 mm. To protect an organic light emitting diode (OLED) against moisture, inorganic passivation layers are provided on the upper and lower sides of the flexible display. Using our transfer technology, high density passivation layers can be obtained. The measured water vapor transmission rate of the layer is 7 × 10^?6 g/m²?day or less, which improves OLED reliability. With these techniques, we have developed a book‐type display, which is repeatedly foldable like a book, and a tri‐fold display including a display area, which is foldable in three.     

Revolving Vernier Mechanism Controls Size of Linear Homomultimer

A new kind of the Vernier mechanism that is able to control the size of linear assembly of DNA origami nanostructures is proposed. The mechanism is realized by mechanical design of DNA origami, which consists of a hollow cylinder and a rotatable shaft in it connected through the same scaffold. This nanostructure stacks with each other by the shape complementarity at its top and bottom surfaces of the cylinder, while the number of stacking is limited by twisting angle of the shaft. Experiments have shown that the size distribution of multimeric assembly of the origami depends on the twisting angle of the shaft; the average lengths of the multimer are decamer, hexamer, and tetramer for 0°, 10°, and 20° twist, respectively. In summary, it is possible to affect the number of polymerization by adjusting the precise shape and movability of a molecular structure.     

Meshless analysis of potential problems in three dimensions with the hybrid boundary node method

Combining a modified functional with the moving least‐squares (MLS) approximation, the hybrid boundary node method (Hybrid BNM) is a truly meshless, boundary‐only method. The method may have advantages from the meshless local boundary integral equation (MLBIE) method and also the boundary node method (BNM). In fact, the Hybrid BNN requires only the discrete nodes located on the surface of the domain. The Hybrid BNM has been applied to solve 2D potential problems. In this paper, the Hybrid BNM is extended to solve potential problems in three dimensions. Formulations of the Hybrid BNM for 3D potential problems and the MLS approximation on a generic surface are developed. A general computer code of the Hybrid BNM is implemented in C++. The main drawback of the ‘boundary layer effect’ in the Hybrid BNM in the 2D case is circumvented by an adaptive face integration scheme. The parameters that influence the performance of this method are studied through three different geometries and known analytical fields. Numerical results for the solution of the 3D Laplace's equation show that high convergence rates with mesh refinement and high accuracy are achievable. Copyright © 2004 John Wiley & Sons, Ltd.