Enhanced performance of PbPc photosensitive organic field effect transistors by inserting different-thickness pentacene inducing layers

Lead phthalocyanine (PbPc) based photosensitive organic field effect transistors (PhOFETs) with different-thickness pentacene inducing layers (INLs) inserted between SiO₂ and PbPc layer were fabricated and characterized. The photoelectric measurements demonstrate that the device with 2-nm-thick pentacene INL exhibits the largest photoresponsivity of 505.75 mA/W and maximum photo/dark current ratio of 405.35 in all devices. For this, we give an overall explanation that different-thickness INLs display different continuity and crystallinity and thus produce strong or weak template inducing. Especially, when the INL thickness (δ) is 2 nm a quasi-continuous and highly crystalline approximate-monolayer INL forms on SiO₂ surface, which may play a strong role of template inducing, thus causing its upper PbPc film to demonstrate the strongest triclinic (3 0 0) line and the strongest NIR absorption in series PbPc films. When δ = 1 nm, pentacene does not form a continuous film. And when δ = 5 or 10 nm, a continuous multilayer INL with a declined crystallinity due to possible lattice mismatch forms on SiO₂ surface and gives a weakened template inducing. Thereby, it can be recognized that inserting a pentacene INL can markedly enhance the performance of single layer PbPc PhOFET and the optimum INL thickness is proved ∼2 nm in present conditions.     

Recording and thermo developing of latent phase holograms in the photosensitive polymer material based on anthracylacetonatoboron difluoride

The diffraction efficiency of photoinduced gratings recorded in polymethylmethacrylate doped with anthracylacetonatoboron difluoride was shown to be increased from 8% to 70% due to the post-exposure heating of the material to 75 °C. Mechanism of the thermal development was determined to be the diffusion of the initial photoactive additives molecules and the photoproduct. This process shifts the minimum of the material frequency-contrast characteristic into the low-frequency region as well as significantly increases the amplitude of the refractive index modulation for gratings with the spatial frequencies up to 2500 mm⁻¹.     

The Basilica of Santa Maria di Collemaggio in L＇Aquila： Modern Provisional Measures

The case in analysis is Santa Maria di Collemaggio, the church symbol of the town of L＇Aquila and the most important example of Romanesque style in Abruzzi, tragically damaged by the earthquake in 2009. The following paper starts with an accurate analysis of the Basilica, whose historical, stylistical cultural characteristics make it an unicum in the whole urban environment. The authors tried to identify in which way these values have been compromised or altered after the earthquake through several analysis （surveys, historical researches etc.） aiming at the recognition of collapses, the cracks profile, the structural transformations caused by the provisional measures： the goal is to provide a kind of Basilica ＂cognitive manual＂ that will be useful for the future interventions. This first analysis allowed to understand many aspects： on the one hand, the constructive phases and which damages were caused by past careless interventions of restoration, drawing attention to the vulnerability elements of the Basilica; on the other hand, the innovative technologies and materials of the post-seismic provisional measures and their exact location.     

制孔分层损伤对CF/PEEK复合材料拉伸性能和表面应变分布的影响

目的 研究钻削制孔表面分层损伤与拉伸载荷下开孔碳纤维增强聚醚醚酮（CF/PEEK）复合材料表面应变分布的相关性。方法 通过对CF/PEEK复合材料层合板进行钻削制孔实验,分析不同进给速度对钻削温度、钻削轴向力、制孔出口表面分层和孔壁表面损伤的影响。采用数字图像相关技术（DIC）和力学实验相结合的方法,研究分层损伤程度对开孔CF/PEEK复合材料层合板拉伸性能和表面应变分布的影响。使用扫描电镜观测开孔试件的断裂形貌,分析开孔试件受拉伸载荷时的破坏模式。结果 随着进给速度的增加,钻削温度降低,钻削轴向力提高,出口表面分层和孔壁损伤程度加剧。随着分层损伤程度的增加,层合板的拉伸强度呈现出降低的趋势,试件的拉伸强度从558.4 MPa降低到525.63 MPa,降低了5.87%。在中应力和高应力状态下,试件x方向的最大负应变随着分层损伤程度的增加而增加。在高应力状态下,试件y方向的最大正应变随着分层损伤程度的增加而增加。试件的断裂方式主要是基体开裂、分层和纤维撕裂,断口有纤维脱落和纤维拔出,垂直于载荷方向的纤维破坏模式为剥离破坏,与载荷方向一致的纤维破坏模式为拉伸破坏。结论 钻削制孔表面分层损...     

Flood Damage Reduction

Abstract

A fundamental conflict occurs when a floodplain, fluvio-morphologically formed by the river for draining its high flows, is occupied and developed by humanity. Consequently, damages are experienced that are the inevitable costs of occupancy of the floodplain. A systematic methodology is suggested for formulating an optimal scheme for addressing any flood situation with its own unique characteristics. This methodology embraces all available measures, structural and non-structural, traditional and modern, in evolving the best scheme. Diverse flood situations in New Brunswick (Canada), the Nile River Basin and Bangladesh exemplify three flooding situations radically different in origin and character. Finally, some important conclusions are drawn and recommendations are made for approaching solutions to major flood problems     

光控介质谐振器稳频FET振荡器研究

本文报导我们对光控介质谐振器稳频MESFET振荡器的研究状况，包括被控介质谐振器模型的建立、电磁分析和实验研究。采用有限元法，借助Ansoft三维仿真软件分析从实际振荡器结构中提取出的叠层DR模型。应用二维阻抗边界条件处理光照下光敏材料的光学效应，得出明晰的物理概念，使复杂问题简化，并较好地验证了实验结果。     

东北地区夏季旱涝、低温冷害评估系统的设计与实现

通过对东北地区夏季旱涝及低温冷害对农业生产影响的研究，确立了在山区及平原地区旱涝、年度低温冷害发生的指标以及减产幅度。利用VB6.0编程语言和AUTHORWARE多媒体软件建成了东北夏季旱涝及低温冷害对农业生产影响评价系统和防御服务系统。该系统可利用预报气象信息对旱涝和低温冷害发生程度进行了预测和评价。     

Photopolymerization of thiol-allyl ether and thiol-acrylate coatings with visible light photosensitive systems

The photoinitiated polymerization reactions of thiol-allyl ether and thiol-acrylate mixtures under visible light in the presence of several visible photoinitiating systems have been investigated. Remarkable high yield of conversions as well as fast rates of polymerization are observed; a photoinitiating system based on Rose Bengal/Ferrocenium salt/hydroperoxide is particularly efficient. The role of a large variety of photoinitiating systems and the mechanisms involved in the initiation step are discussed.     

辽河油田热采井套损机理分析与治理措施

通过对辽河油田油水井套管损坏情况的全面调查与分析,找出了该油田稠油井套管损坏的主要原因,针对热采井及中深层套损严重井只能开窗侧钻的现状,提出了适用于热采套损井修复复产的治理技术,并对其原理进行了深入探讨.其中套损井加固密封工艺2002年度在曙光采油厂、锦州采油厂分别进行了5口井的现场试验,成功率达100%.     

Failure investigation and condition assessment using field metallography

In many cases it is not possible or practical to extract samples for a subsequent laboratory failure investigation. Examples of such cases are condition assessments of larger structures that have been exposed to fire and examination of cracks or defects observed in components such as pressure vessels which are still in operation. In other cases the first step of a failure investigation will be to gather a maximum of information on-site, prior to a laboratory examination. In all these situations field metallography represents a useful tool to obtain as much information as possible.

The most common field metallographic tools are briefly presented in the article.

Cases of failure investigations where field metallography has been an important tool will be presented. This includes:

• Assessment of defects in a pressure vessel in service at elevated temperature.

• Condition assessment of a ship hull damaged by fire during construction.

• Investigation of fractured wheel shaft on high speed train.