Polymorphisms of the estrogen receptor alpha (ESR1) gene and the risk of Alzheimer's disease in a southern Chinese community

Background: Alzheimer's disease (AD) is a neurodegenerative disease with a higher prevalence in women. Expression of estrogen receptor 1 (ESR1) gene has been identified throughout the brain. Owing to the putative neuroprotective effects of estrogen, estro

The feasibility of milkfish (Chanos chanos) aquaculture in Solomon Islands

Fish is crucial to food and nutrition security in Solomon Islands, and demand is expected to increase due to a growing population. However, it is projected that current capture fisheries production will not meet this growing demand. Aquaculture has the potential to mitigate the capture fishery shortfall, and the Government of Solomon Islands is prioritizing aquaculture as a solution to meet future food and income needs. Aquaculture in Solomon Islands is still in early development. Mozambique tilapia (Oreochromis mossambicus) is farmed for household consumption, but its prolific reproductive rate and resulting slow growth limit its potential as a commercial aquaculture species. More productive fish species that are not indigenous to Solomon Islands but are successfully farmed overseas could be introduced; however, such a decision needs to take into account the potential ecological or social impacts. For land-based pond aquaculture, the only indigenous species that has been farmed extensively elsewhere is milkfish (Chanos chanos). This report presents a feasibility assessment for milkfish farming in Solomon Islands. It synthesizes the current knowledge about milkfish farming and presents results of a 4-year study on the potential for milkfish aquaculture in Solomon Islands.

Experimental investigation of turbine stator well rim seal, reingestion and interstage seal flows using gas concentration techniques and displacement measurements

Gas turbine engine performance requires effective and reliable internal cooling over the duty cycle of the engine. Life predictions for rotating components subject to the main gas path temperatures are vital. This demands increased precision in the specification of the internal air system flows which provide turbine stator well cooling and sealing. This in turn requires detailed knowledge of the flow rates through rim seals and interstage labyrinth seals. Knowledge of seal movement and clearances at operating temperatures is of great importance when prescribing these flows. A test facility has been developed at the University of Sussex, incorporating a two stage turbine rated at 400 kW with an individual stage pressure ratio of 1.7:1. The mechanical design of the test facility allows internal cooling geometry to be rapidly re-configured, while cooling flow rates of between 0.71 CW, ENT and 1.46 C W, ENT, may be set to allow ingress or egress dominated cavity flows. The main annulus and cavity conditions correspond to in cavity rotational Reynolds numbers of 1.71×106< Reφ <1.93×106. Displacement sensors have been used to establish hot running seal clearances over a range of stator well flow conditions, allowing realistic flow rates to be calculated. Additionally, gas seeding techniques have been developed, where stator well and main annulus flow interactions are evaluated by measuring changes in gas concentration. Experiments have been performed which allow rim seal and re-ingestion flows to be quantified. It will be shown that this work develops the measurement of stator well cooling flows and provides data suitable for the validation of improved thermo-mechanical and CFD codes, beneficial to the engine design process. Copyright © 2011 by Rolls-Royce plc.

Lift and the leading edge vortex

Leading edge vortices are considered to be important in generating the high lift coefficients observed in insect flight and may therefore be relevant to micro-air vehicles. A potential flow model of an impulsively started flat plate, featuring a leading edge vortex (LEV) and a trailing edge vortex (TEV) is fitted to experimental data in order to provide insight into the mechanisms that influence the convection of the LEV and to study how the LEV contributes to lift. The potential flow model fits the experimental data best with no bound circulation, which is in accordance with Kelvin's circulation theorem. The lift-to-drag ratio is well approximated by the function 'cot α' for α > 15°, which supports the tentative conclusion that shortly after an impulsive start, at post-stall angles of attack, lift is caused non-circulatory forces and by the action of the LEV as opposed to bound circulation. Copyright © 2012 by C. W. Pitt Ford.

Quantitative strain characterization of SiGe heterostructures by high-resolution transmission electron microscopy

We report the quantitative strain characterization in semiconductor heterostructures of silicon-germaniums (Si(0.76)Geo(0.24)) grown on Si substrate by an ultra-high vacuum chemical vapor deposition system. The relaxed SiGe virtual substrate has been achieved by thermal annealing of the SiGe film with an inserted Ge layer. Strain analysis was performed using a combination of high-resolution transmission electron microscopy and geometric phase analysis.

Unusual carrier thermalization in a dilute GaAs1-xNx alloy

Photoluminescence (PL) properties of the E-0, E-0+Delta(0), and E+ bands in an x=0.62% GaAs1-xNx alloy were investigated in detail, including their peak position, linewidth, and line shape dependences on the excitation energy, excitation power, and temperature, using micro-PL. The hot electrons within the E+ band are found to exhibit highly unusual thermalization, which results in a large blueshift in its PL peak energy by >2k(B)T, suggesting peculiar density of states and carrier dynamics of the E+ band.

Photoluminescence from the nitrogen-perturbed above-bandgap states in dilute GaAs1-xNx alloys: A microphotoluminescence study

Using microphotoluminescence (mu-PL), in dilute N GaAs1-xNx alloys, we observe a PL band far above the bandgap E-0 with its peak energy following the so-called E+ transition, but with contribution from perturbed GaAs host states in a broad spectral range (> 100 meV). This finding is in sharp contrast to the general understanding that E+ is associated with a well-defined conduction band level (either L-1c or N-x). Beyond this insight regarding the strong perturbation of the GaAs band structure caused by N incorporation, we demonstrate that a small amount of isoelectronic doping in conjunction with mu-PL allows direct observation of above-bandgap transitions that are not usually accessible by PL.

Replacement of methane from quartz sand-bearing hydrate with carbon dioxide-in-water emulsion

The replacement of CH4 from its hydrate in quartz sand with 90:10, 70:30, and 50:50 (W-CO2:W-H2O) carbon dioxide-in-water (C/W) emulsions and liquid CO2 has been performed in a cell with size of empty set 36 x 200 mm. The above emulsions were formed in a new emulsifier, in which the temperature and pressure were 285.2 K and 30 MPa, respectively, and the emulsions were stable for 7-12 h. The results of replacing showed that 13.1-27.1%, 14.1-25.5%, and 14.6-24.3% of CH4 had been displaced from its hydrate with the above emulsions after 24-96 It of replacement, corresponding to about 1.5 times the CH4 replaced with high-pressure liquid CO2. The results also showed that the replacement rate of CH4 with the above emulsions and liquid CO2 decreased from 0.543, 0.587, 0.608, and 0.348 1/h to 0.083, 0.077, 0.069, and 0.063 1/h with the replacement time increased from 24 to 96 h. It has been indicated by this study that the use of CO2 emulsions is advantageous compared to the use of liquid CO2 in replacing CH4 from its hydrate.

有机电磷光器件的研究

自1987年C.W.Tang等人首次报道以Alq_3为发光材料的多层结构有机电致发光器件以来，由于其简单工艺、低成本、主动发光、快速响应以及大面积和柔性可弯曲显示等特点，使其在未来的平板显示领域显示了诱人的应用前景，其研究倍受关注。近些年来，有机发光二极管己经开始商品化。其中，三重态电磷光有机发光材料以其在效率，亮度等方面的优秀性能表现，成为了该领域重要的研究课题。在众多的电磷光材料中，重金属铱的配合物的很多优点引起了广泛的研究。铱配合物电磷光不仅具备了磷光材料理论上可能达到了100％内量子效率的优势，还以其独特的金属一配体电荷跃迁发光性质实现了可见光范围内的全色发光。本论文主要研究了有机电磷光铱配合物的电致发光性能，从不同分子结构铱配合物在不同掺杂浓度下的优化、器件结构设计、母体材料选择以及电磷光发光器件的瞬态特性等方面进行了详细研究，开发出了高效率纯红光有机电磷光发光器件，实现了高效率单层电磷光聚合物发光二极管，用稀土配合物做电磷光掺杂的母体在一定程度上解决了电磷光器件在高电流密度下快速退化问题，对有机电磷光器件的三重态一三重态湮灭和激子衰减动力学过程有了初步认识。（1）研究了几种新型红光铱配合物的电致发光性能：①开发出了以毗嗦为配体的铱配合物，发现其发光光谱（光致和电致）均比哇琳为配体的铱配合物有大幅度的红移，如此制备出了主峰在677nm，色坐标为（0.71，0.28）的深红色有机电磷光器件，器件的外量子效率达到了5.5％以上；②比较了以嗯哇和噬哇为配体的配合物的电致发光性能，发现在结构相近的情况下，电负性越强的原子导致发射光谱蓝移，而在配体上引入高电负性O原子在一定程度上提高了器件的电致发光性能。（2）在高效有机发光器件的制备和结构优化等方面开展的一系列工作得到了如下结论：①不同取代基团配体铱配合物依赖于掺杂浓度，通过优化器件可以获得最好的电致发光性能。②用旋涂方法，通过对电子和空穴注入和传输的调控制备出了高效率单层有机电磷光发光器件，最大发光效率达到了25.2cd／A，由于减少了电子和空穴在磷光分子的直接俘获，避免了空间电荷积累引起的空间电场问题，使器件的电致发光性能得到了显著地提高。③研究了用稀土试络合物作为主体材料，掺杂一种铱配合物的电磷光有机发光二极管的电致发光性能，发现在较高的电流密度下，器件的电致发光效率仍然保持较好的稳定性，有效地降低了三重态一三重态湮灭引起的退化问题。（3）我们用瞬态电致发光方法详细研究了电磷光有机发光器件的三重态一三重态湮灭和激子衰减动力学过程，确定了不同取代基团苯基噬哇铱配合物的三重态激子的寿命τ、三重态一三重态湮灭常数K和饱和电流以及它们与器件电致发光效率的关系，这方面的研究对澄清有机发光器件的工作原理和退化机制，进一步改善器件性能具有重要意义。