Fabrication & characterization of macroporous CdSe nanostructure via colloidal crystal templating with electrodeposition method

Large area ordered arrays of macroporous Cadmium Selenide (CdSe) nanostructure, which possesses high refractive index and negligible absorption in the visible spectrum critical for the realization of photonic band gaps, was prepared via colloidal templating by galvanostatic electrodeposition. This work investigates the effect of electrodeposition parameters on the macroporous CdSe nanostructure. Field Emission Scanning Electron Microscope (FESEM) images showed two and three dimensional porous structures, consisting of interconnected close-packed arrays of pores. For CdSe thin film of thickness less than 1/3 of the diameter of a polystyrene sphere, it showed a monolayer of circular pores. As for film thickness close to the diameter of the sphere, the pores adopted irregular rounded triangular shapes. When the film thickness was more than one layer of the colloidal polystyrene template, the pores were spherical and had the same diameter as the polystyrene spheres. X-ray Diffraction (XRD) showed that the CdSe films prepared had a cubic structure with nanometer grain size, which was smaller than the diameter of the template spheres as well as the diameter of the interconnected channels. A range of 45–70 nm thick CdSe films with > 90% optical transmittance showed that there was negligible absorption at wavelength of 750 nm. In addition, the CdSe thin film exhibited a band gap energy of 2.07 eV, blue-shifted from the characteristic 1.7 eV of CdSe. This blue-shift characteristic of the deposited CdSe film further indicated that it was nanocrystalline which is potentially useful in photonic applications.     

Efficient DSR route request flooding with directional antennas

In this paper, an efficient scheme for flooding the DSR route request in ad hoc networks using directional antennas is proposed. The scheme makes use of the local neighbor information provided by the neighbor discovery scheme. Route request packets are forwarded to selected representative neighbors using directional transmissions instead of being broadcast to all neighbors. Two strategies are proposed to efficiently select the representative neighbors: fixed branching and honeycomb strategies. The fixed branching strategy selects one representative neighbor in each predefined forwarding direction, while the honeycomb strategy selects representative neighbors to create a hexagonal tiling pattern. Simulation results show that the proposed strategies are able to achieve a high route discovery success rate while keeping the number of involved nodes and the number of transmissions low.     

Compensation of audio data with a high frequency components for realistic media FTV

Like the concept of free-viewpoint TV (FTV), the audio data should be rendered according to video data. However, on condition that minimum numbers of microphone are used, it is difficult to acquire accurate audio signal for rendering audio data to the image with the choice of view point. Especially, degradation of high frequency components (HFC) happens due to the characteristic of polar pattern for microphone. The degradation of HFC causes imperfection of signal restoration and leads to the degradation of clarity for hearing. In this paper, a compensation method for the degradation of HFC audio signal is proposed for producing an immersive audio effect at realistic media. Our experimental results show that low frequency components (LFC) of audio signal had a little directional degradation in spite of effect of the polar patterns of microphone and the compensation of HFC can be realized with adapting the attenuation inclination of LFC. This research is expected to be helpful for producing an immersive audio effect for a realistic media.     

DBN wavelet transform denoising method in soybean straw composition based on near-infrared rapid detection

In Hei Longjiang Province of China, ten million tons of soybean straws are produced every year, most of which are burned or discarded. The comprehensive utilization rate is less than 5 %. However, as a kind of high-quality raw material resources, the soybean straw is the main material when producing fuel ethanol and biodiesel. The traditional chemical detection technology was always applied to test the quality of straws’ internal components, which needs long time and high cost. Therefore, this research adopted near-infrared spectroscopy technology to establish models to achieve rapid detection of straw’s internal components. One hundred and fifty-two samples of straw were collected within Heilongjiang Province, and the main ingredients, lignin and hemicellulose, were chosen as the research objects. K-stone method is used to divide into calibration and validation sets. The correlation coefficient is adopted to select and validate characteristic bands. After removal of the abnormal sample by concentration of residual method, the emphasis is put on the effect of removal of spectrum noise by applying the wavelet transform. The experimental results are that the model has good stability under the full spectrum band 4000–12,000 cm^?1. After the removal of 3 lignin and 3 hemicellulose samples, respectively, the R ² of calibration set of lignin and hemicellulose models increased significantly, from 0.5836436 and 0.4994598 to 0.6994097 and 0.6943559, respectively. However, after the 5-layer decomposition of DB2 wavelet, the R ² increased to 0.8075574 and 0.8214309 separately. The validation set’s root mean square error prediction (RMSEP) fell from 0.7738772 and 0.3069899 to 0.5979685 and 0.2761462. After the conversion, the relative standard deviations (RSD) are 1.92 and 1.86 %, respectively. Unknown samples can be real-time predicted in short times after building the model, and the prediction process needs only 1960s. The experiments show that it is feasible to employ near-infrared spectroscopy method for rapid detection of straw components, which provides a new method to detect the straw ingredients rapidly in the future.     

A 1.8-V 2.4/5.15-GHz dual-band LCVCO in 0.18-/spl mu/m CMOS technology

A dual band, fully integrated, low phase-noise and low-power LC voltage-controlled oscillator (VCO) operating at the 2.4-GHz industrial scientific and medical band and 5.15-GHz unlicensed national information infrastructure band has been demonstrated in an 0.18-/spl mu/m CMOS process. At 1.8-V power supply voltage, the power dissipation is only 5.4mW for a 2.4-GHz band and 8mW for a 5.15-GHz band. The proposed VCO features phase-noise of -135dBc/Hz at 3-MHz offset frequency away from the carrier frequency of 2.74GHz and -126dBc/Hz at 3-MHz offset frequency away from 5.49GHz. The oscillator is tuned from 2.2 to 2.85GHz in the low band (2.4-GHz band) and from 4.4 to 5.7GHz in the high band (5.15-GHz band).     

Development of least-square-based two-dimensional finite-difference schemes and their application to simulate natural convection in a cavity

In this paper, two-dimensional mesh-free finite-difference schemes for solving incompressible viscous flows are presented. The method is based on the use of a weighted least-square approximation procedure together with a Taylor series expansion of the unknown function. Discretization error for derivatives is investigated analytically on the uniform mesh and the convergence property of the method is numerically tested. The role of the weighting function playing in the method is studied. Neumann-type boundary condition is treated by applying locally orthogonal boundary grids. Application to a problem of natural convection in a cavity is demonstrated on three different types of point distribution.     

A 20‐node hexahedron element with enhanced distortion tolerance

This paper presents a distortion resistant 20‐node hexahedron element that employs two different sets of shape functions for the trial and test functions. The formulation seeks to satisfy the continuity and completeness requirements by exploiting the intrinsic properties of these two sets of shape functions. Several test problems are used to assess the performance of the element under various mesh distortions. The ability of the proposed as well as the classical 20‐node element to maintain solution accuracy under severe mesh distortions has been studied. The proposed element exhibits a very high tolerance to mesh distortions. In particular, for problems involving linear and quadratic displacement fields, the element is capable of reproducing exact solution under all admissible geometrical distortions of the mesh. For test problems involving higher‐order displacement fields, the performance of the present element is in general better than that of the classical element. Copyright © 2004 John Wiley & Sons, Ltd.     

Real‐Time Imaging of Dynamic Cell Reprogramming with Nanosensors

Cellular reprogramming, the process by which somatic cells regain pluripotency, is relevant in many disease modeling, therapeutic, and drug discovery applications. Molecular evaluation of reprogramming (e.g., polymerase chain reaction, immunostaining) is typically disruptive, and only provides snapshots of phenotypic traits. Gene reporter constructs facilitate live‐cell evaluation but is labor intensive and may risk insertional mutagenesis during viral transfection. Herein, the utilization of a non‐integrative nanosensor is demonstrated to visualize key reprogramming events in situ within live cells. Principally based on sustained intracellular release of encapsulated molecular probes, nanosensors successfully monitored mesenchymal‐epithelial transition, pluripotency acquisition, and transdifferentiation events. Tracking the dynamic expression of four pivotal biomarkers (i.e., THY1, E‐CADHERIN, OCT4, and GATA4 mRNA), nanosensor signal showed great agreement with polymerase chain reaction and gene reporter imaging (R² > 0.9). Overall, such facile, versatile nanosensor enables real‐time monitoring of low‐frequency reprogramming events, thereby useful for high‐throughput assessment, optimization, and biomarker‐specific cell enrichment.     

Therapeutic‐Gas‐Responsive Hydrogel

Nitric oxide (NO) is a crucial signaling molecule with various functions in physiological systems. Due to its potent biological effect, the preparation of responsive biomaterials upon NO having temporally transient properties is a challenging task. This study represents the first therapeutic‐gas (i.e., NO)‐responsive hydrogel by incorporating a NO‐cleavable crosslinker. The hydrogel is rapidly swollen in response to NO, and not to other gases. Furthermore, the NO‐responsive gel is converted to enzyme‐responsive gels by cascade reactions from an enzyme to NO production for which the NO precursor is a substrate of the enzyme. The application of the hydrogel as a NO‐responsive drug‐delivery system is proved here by revealing effective protein drug release by NO infusion, and the hydrogel is also shown to be swollen by the NO secreted from the cultured cells. The NO‐responsive hydrogel may prove useful in many applications, for example drug‐delivery vehicles, inflammation modulators, and as a tissue scaffold.