热象无损检测技术应用

本文将热象无损检测技术应用于鉴定受测物结构和性质,并测出受测物中的缺陷,实验结果取得了较为满意的进展。     

奇异积分方程理论在迁移方程中的应用

本文利用奇异积分方程理论，对于具有非零边界条件的球对称模型的散射裂为函数，给出了直接求妥方法并给出了解的明显表达式。     

EFFECT OF CRYSTALLIZATION TEMPERATURE ON MCM-41 SYNTHESIS

在Ｎａ２ＯＳｉＯ２ＣＴＡＢＨ２Ｏ四元水热体系中系统地考察了晶化温度对中孔ＭＣＭ４１分子筛合成及其骨架结构的影响。实验结果表明，提高晶化温度虽然能明显加快晶化速率，缩短晶化时间，但同时样品的结晶度和中孔骨架结构的有序度却被迅速破坏。这些特点与传统沸石的合成过程完全不同，其原因主要是合成ＭＣＭ４ｌ时所用的模板剂及其在合成中所起的模板作用与传统沸石完全不同。相对低的晶化温度（如１００℃）有利于高质量和高热稳定性的中孔ＭＣＭ４ｌ分子筛的合成。     

2-芳基苯丙酸类药物在混合溶剂中的荧光光谱

测定了298K时2-芳基丙酸类药物普拉洛芬、酮洛芬、卡洛芬、萘普生在二元混合溶剂中的荧光光谱,采用Jouyban-Acree模型拟合了荧光强度（FI）数据,平均偏差为1.9％,当采用Yalkowsky方程拟合时,平均偏差达到13.5％.首次采用Jouyban-Acree模型拟合最大荧光发射波长,平均误差为0.3nm,而采用Yalkowsky方程时,误差为0.9nm.结果表明Jouyban-Acree模型能够很好预测混合水溶液中药物的荧光强度及荧光最大发射波长,当数据较少时,Yalkowsky方程也能预测混合溶剂中的最大发射波长.     

High-speed complex conjugate resolved retinal spectral domain optical coherence tomography using sinusoidal phase modulation

We demonstrate high-speed complex conjugate artifact (CCA) resolved imaging of human retina in vivo using spectral domain optical coherence tomography. This technique utilizes sinusoidal reference mirror modulation to implement high-speed integrating buckets acquisition and a quadrature projection reconstruction algorithm in postprocessing. This method is illustrated experimentally using sets of four integrating bucket phase scans, acquired at 52 kHz, for DC suppression of 73 dB and complex conjugate suppression of 35 dB. Densely sampled (3000 A-scans/image, acquired at 4.3 images/s) full-depth in vivo images of optic nerve head show CCA suppression for most image reflections to the noise floor.     

Four-dimensional scheduling for uplink dynamic bandwidth allocation in OFDM-PON

Orthogonal frequency division multiplexing passive optical network (OFDM-PON) has been considered a promising access solution to meet the variable bandwidth demand. In this paper, a novel scheduling for dynamic bandwidth allocation (DBA) at medium access control (MAC) layer is proposed for uplink transmission of OFDM-PON. In order to utilize the bandwidth efficiently, scheduling in four dimensions is adopted in the proposed DBA algorithm. Four dimensions stand for frequency domains, time domains, modulation formats and power allocations. The algorithm is quite flexible. Simulation results and analysis show that the proposed algorithm can efficiently utilize the OFDM bandwidth and make the system highly energy-efficient.     

Sonochemical fabrication of Fe3O4 nanoparticles on reduced graphene oxide for biosensors

This study synthesized Fe₃O₄ nanoparticles of 30–40 nm by a sonochemical method, and these particles were uniformly dispersed on the reduced graphene oxide sheets (Fe₃O₄/RGO). The superparamagnetic property of Fe₃O₄/RGO was evidenced from a saturated magnetization of 30 emu/g tested by a sample-vibrating magnetometer. Based on the testing results, we proposed a mechanism of ultrasonic waves to explain the formation and dispersion of Fe₃O₄ nanoparticles on RGO. A biosensor was fabricated by modifying a glassy carbon electrode with the combination of Fe₃O₄/RGO and hemoglobin. The biosensor showed an excellent electrocatalytic reduction toward H₂O₂ at a wide, linear range from 4 × 10^?6 to 1 × 10^?3 M (R² = 0.994) as examined by amperometry, and with a detection limit of 2 × 10^?6 M. The high performance of H₂O₂ detection is attributed to the synergistic effect of the combination of Fe₃O₄ nanoparticles and RGO, promoting the electron transfer between the peroxide and electrode surface.     

Externally applied stress sign and film elastic properties effects on brittle film fracture

Rectangular stainless steel samples with TiN film deposited on the front lateral surface were loaded in three-point bending to the maximum normal strain of 6%. Scanning electron microscopy showed that vertical cracks appeared in the tension zone when the tensile strain exceeded 1.5%, while horizontal cracks appeared in the compression zone when the compressive strain exceeded –2.9%. Film cracks in the compressive zone originate from the tensile stress imposed by the plastically deformed substrate due to the Poisson’s expansion. Taking plastic deformation and Poisson’s expansion of the substrate in compression into account, theoretical analysis of normal stress distribution along the cracked film segment in compression is presented. Substrate strain and film elastic properties affect film cracking in the compressive zone. At larger compressive strain, some transverse cracks along with buckling cause the film spallation. The presented method is useful for studying brittle film fracture with variable strain levels in a single sample.