Al2O3—Si3N4—ZrO2多相复合材料在燃煤MHD发电中的应用

采用Ａｌ２Ｏ３基料，添加第二相（ＺｒＯ２，Ｓｉ３Ｎ４）和纤维相（ＺｒＯ２，（ｆ），以热压法制成Ａｌ２Ｏ３－Ｓｉ３Ｎ４－ＺｒＯ２多相复合材料。研究表明，新材料在青静态和动态试验中表现出良好的综合性能：１０７３Ｋ时的高温电阴率ｐ＝１．２４×１７＾７Ω．ｃｍ；静态熔渣最大腐蚀速率Ｖｓ＝０．１６μｍ／ｈ；动态最大腐蚀速率Ｖｄ＝０．４４９μｍ／ｈ。与Ａｌ２Ｏ３陶瓷相比，室温抗弯强度提高９３％，抗热震临界...     

Using patents and publications to assess R&D efficiency in the states of the USA

Even with the USA spending the largest amounts in R&D, its share in total patent grants worldwide has been declining. This decline is also evident in its share of world scientific publications. These developments have been termed by some as the “American Paradox”. Extant research on R&D efficiency and technological innovation capability has considered the USA as a homogeneous entity and has not focused at the sub-national level. This paper analyses the R&D efficiency of 50 US states and the District of Columbia. R&D efficiency is calculated as the ratio of patents granted and scientific publications to R&D expenditures. Only 14 states out of the 51 regions are found to exhibit positive changes in R&D efficiency between 2004 and 2008. Comparing this performance with that of the BRICS nations over the same period we find that Brazil, India, China and South Korea show significant improvements in R&D efficiency with India taking the lead. This research identifies the states in the US with the highest R&D efficiency and presents benchmarks which can be followed by policy interventions. The paper highlights the importance of conducting analyses of R&D efficiency using patents and publications at the sub-national level for informed policy making.     

Patent backlogs at USPTO and EPO: Systemic failure vs deliberate delays

This paper first describes the so-called patent backlogs and assesses the extent to which they might affect the examination process in major patent offices. Second it puts forward that the root causes of these backlogs in Europe and in the US are different. The backlog at the United States Patent and Trademark Office (USPTO) is three times larger than one at the European Patent Office (EPO) and is essentially due to very low fees and a weak rigor of the examination process. The observed long pendency at the EPO is more due to applicants’ strategic filing behaviors that aim at delaying the grant date, as it marks the start of high expenses due to translation requirements and multiple validation or renewal fees. Since the root causes of backlogs diverge between EPO and USPTO, their cure should also be different.     

基坑开挖爆破作用邻近压力燃气管道动力响应特性研究

确保复杂城市环境基坑爆破开挖工程中邻近压力燃气管道的安全性是关键性问题.依托武汉地铁8号线二期竖井基坑爆破开挖工程,利用现场监测数据建立ANSYS/LS-DYNA三维有限元数值计算模型,分析计算了不同运行压力条件下埋地燃气管道的动力响应特性.研究结果表明:实际工况下管道截面峰值合振速为0.453 cm/s,单元峰值vo...     

Fabrication of 1.55μm Si-Based Resonant Cavity Enhanced Photodetectors

A novel bonding method using silicate gel as bonding medium is developed.High reflective SiO2/Si mirrors deposited on silicon substrates by e-beam deposition are bonded to the active layers at a low temperature of 350℃ without any special treatment on bonding surfaces.The reflectivities of the mirrors can be as high as 99.9%.A Si.based narrow band response InGaAs photodetector is successfully fabricated,with a quantum efficiency of 22.6% at the peak wavelength of 1.54μm,and a full width at half maximum of about 27nm.This method has a great potential for industry processes.     

Investigation and scale-up of hot-melt coating of pharmaceuticals in fluidized beds

This study was performed to investigate and scale-up the hot-melt coating process in fluidized beds. A series of well-designed experiments was carried out in a pilot scale unit with 20 kg product capacity to investigate the effects of process variables on the efficiency of the coating of Cefuroxime Axetil with stearic acid. Results showed that the efficiency is at the highest when the fluidization air flow rate is adjusted by considering the changes in the amount of materials present in the unit as well as the changes in the terminal velocities of particles during the process.With the objective to scale-up the hot-melt coating process from pilot to production scale, a dynamic thermodynamic model based on conservation equations of mass and energy was developed. Predictive accuracy of the model was assessed by applying it to the pilot scale unit and comparing its predictions with the online measurements taken on the same unit. Results showed that the predictions of the model agree well with the measurements. Utilizing this model and taking several experiments performed in the pilot scale unit as a basis, scaling up of the hot-melt coating process was carried out. Comparisons of the model predictions with the measurements taken on the production scale unit (200 kg product capacity) revealed that the model is able to reproduce the product attributes and the outlet air temperatures across scales. Therefore, it proves to be a promising tool that can be used in the scale-up of the hot-melt coating processes in fluidized beds.     

Applying dry powder coatings to pharmaceutical powders using a comil for improving powder flow and bulk density

A method for applying nano-sized silicon dioxide guest particles onto host pharmaceutical particles (a.k.a. “dry-coating” or “nanocoating”) has been developed using conventional pharmaceutical processing equipment. It has been demonstrated that under selected conditions, a comil can be used to induce sufficient shear to disperse silicon dioxide particles onto the surfaces of host particles such as active pharmaceutical ingredients (API) without significant host particle attrition. In accordance with previous studies on dry coating, the dispersed silicon dioxide adheres to the host particle surface through van der Waals attractions, and reduces bulk powder cohesion. In this work, laboratory and pilot scale comils were used to dry coat pharmaceutical API and excipient powders with 1% w/w silicon dioxide by passing them through the mill with an appropriate combination of screen and impeller. In general, the uncoated powders exhibited poor flow and/or low bulk density. After dry coating with a comil, the powders exhibited a considerable and in some cases outstanding improvement in flow performance and bulk density. This coating process was successful at both the laboratory and pilot scale with similar improvements in flow. The superior performance of the coated powders translated to subsequent formulated blends, demonstrating the benefit of using nanocoated powders over uncoated powders. This particle engineering work describes the first successful demonstration of using a traditional pharmaceutical unit operation that can be run continuously to produce uniform nanocoating and highlights the substantial improvements to powder flow properties when this approach is used.     

Graphene-based polymer nanocomposites

Graphene-based materials are single- or few-layer platelets that can be produced in bulk quantities by chemical methods. Herein, we present a survey of the literature on polymer nanocomposites with graphene-based fillers including recent work using graphite nanoplatelet fillers. A variety of routes used to produce graphene-based materials are reviewed, along with methods for dispersing these materials in various polymer matrices. We also review the rheological, electrical, mechanical, thermal, and barrier properties of these composites, and how each of these composite properties is dependent upon the intrinsic properties of graphene-based materials and their state of dispersion in the matrix. An overview of potential applications for these composites and current challenges in the field are provided for perspective and to potentially guide future progress on the development of these promising materials.     

High internal phase emulsion templating as a route to well-defined porous polymers

The use of high internal phase emulsions (HIPEs) as templates to create highly porous materials (PolyHIPEs) is described. Polymerisation occurs around emulsion droplets, which create voids in the final material. The void fraction is very high and can reach levels of 0.99. Varying the emulsion composition can control features of the morphology of the resulting porous materials, such as the void diameter and degree of interconnection. Other parameters can also be varied, for example surface area can be increased from 3 to around 700 m² g⁻¹. Rubbery materials can be produced from hydrophobic elsatomers and PolyHIPEs with high thermo-oxidative stability are prepared from high performance materials such as poly(ether sulfone). The highly porous materials so produced are finding applications in areas such as solid supported organic chemistry, sensors, cell culturing and tissue engineering.     

Transmission electron microtomography in polymer research

This feature article summarizes recent advances in an emerging three-dimensional (3D) imaging technique, transmission electron microtomography (TEMT), and its applications to polymer-related materials, such as nanocomposites and block copolymer morphologies. With the recent developments made in TEMT, it is now possible to obtain truly quantitative 3D data with sub-nanometer resolution. A great deal of new structural information, which has never been obtained by conventional microscopy or various scattering methods, can be directly evaluated from the 3D volume data. It has also been demonstrated that, with the combination of TEMT and scattering methods, it becomes possible to study structures that have not yet been characterized. The structural information obtained from such 3D imaging provides a good opportunity not only to gain essential insight into the physics of self-assembling processes and the statistical mechanics of long chain molecules, but also to establish the “structure-property” relationship in polymeric materials.