烧结气氛对合成MgAl2O4-Ti(C,N)复合陶瓷的影响

以金属铝粉、钛白粉和轻烧MgO细粉为原料,通过设计100%焦炭粒(简称C气氛),10%钛白粉 90%焦炭粒(简称TC气氛),以及10%硅微粉 90%焦炭粒(简称SC气氛)3种埋粉条件下的高温烧结还原性气氛,采用X射线衍射仪(XRD)、扫描电镜(SEM)和微区电子探针分析(EPMA)等手段,研究了铝热还原氮化法(1600℃3h)制备MgAl2O4-Ti(C,N)复合陶瓷在不同烧结气氛下的相组成和显微结构的变化。结果表明在不同气氛下,烧后试样的主要物相均为MgAl2O4和Ti(C,N),Ti(C,N)可能会固溶氧,气氛对Ti(C,N)的影响较大。和单纯埋炭气氛下相比,在TC气氛下有助于Ti(C,N)的生成,但晶粒细小;在SC气氛下不利于Ti(C,N)的生成,且有玻璃相存在。     

强化单螺杆挤出机内层流混合的方法

综述了单螺杆挤出机内聚合物熔体层流混合机理的研究进展，对提高混合的措施进行了分析总结，指出了进一步强化混合效果的方法。     

UHMWPE混炼接枝马来酸酐研究

讨论了超高相对分子质量聚乙烯(UHMWPE)混炼接枝马来酸酐(MAH)过程中，单体MAH用量、引发剂DCP用量、交联抑制剂己内酰胺(CAILA)用量、流动改性剂硬脂酸钙(CaSt2)用量及混炼温度、时间等工艺条件对UHMWPE接枝率和凝胶含量的影响。用红外光谱表征了接枝物的存在。并用滴定分析法和重量分析法测定了接枝物UHMWPE～g～MAH的接枝率和凝胶含量。实验表明，MAH用量为5份、DCP为0．15份、CALA为0．1份、CaSt2为1份时。混炼温度175∽180℃。混炼时间14min时，可得到接枝率0．75％、凝胶含量1．48%的UHMWPE接枝物。     

构树皮丙酮抽出物的DEAE—Sephadex分离及GC—MS分析

利用ＤＥＡＥ—Ｓｅｐｈａｄｅｘ分离柱及ＧＣ—ＭＳ对构树皮丙酮抽出物 进行了分离和分析．在丙酮抽出物中中性组分占抽出物的５９．７％，弱酸性 组分和强酸性组分分别占２５．９％和１０．３％．中性组分中不皂化物占 ８９．２％，皂化物仅占８．４％．不皂化物的成分比较复杂，所检出的主要有 甾醇和甾酮类．皂化物中亚油酸占５０％，软脂酸占２１％．弱酸性组分中 ５０％以上是脂肪酸（亚油酸和软脂酸），而没有松香酸．     

化学镀镍石墨粉体的制备

采用化学镀方法在天然鳞片石墨颗粒表面镀镍,对镀镍石墨表面的形貌、成分、结构进行了观察和分析,对镀镍石墨的抗氧化性及表面电位进行了测定。结果表明:在石墨表面形成了较为均匀的镀层,镀层由非晶态的镍和磷组成;镀镍石墨粉体与氧气反应的峰值温度比没有化学镀处理的普通石墨粉体的提高了近80℃,抗氧化性提高;镀镍石墨粉体在水中的Zeta电位绝对值在pH>4.3的位置(等电位点pH=9附近除外)明显大于没有化学镀处理的普通石墨粉体的,分散性有很大的改善。     

钾长石含量对硬质粘土烧结的影响

以硬质粘土粉(w(Al2O3)>38%,粒度为0.002～0.11mm)和钾长石粉(w(K2O Na2O)=13.13%,粒度为0.005～0.11mm)为原料,配制成钾长石粉加入量分别为0、3.76%、5.30%和6.84%的试料(对应的w(K2O Na2O)分别为0.11%、0.6%、0.8%和1.0%),湿磨2h,烘干后以150MPa压力压制成20mm×10mm的试样,然后在1500～1600℃煅烧3h。对煅烧后试样进行了物理性能检测、物相分析和显微结构分析,以研究钾长石含量对粘土烧结的影响。结果表明:钾长石粉加入前后试样的烧结温度分别为1550℃和1500℃;加入钾长石能消除粘土原料煅烧过程中形成的方石英相,使烧成试样中只出现莫来石晶相;加入3.76%～6.84%钾长石粉的试样中莫来石含量达61%～66%,并且莫来石发育较好,呈针状,长度达8μm,直径约0.5μm。     

Trail-following responses of the Argentine ant,Iridomyrmex humilis (Mayr), to a synthetic trail pheromone component and analogs

Behavioral evidence indicates that (Z)-9-hexadecenal (Z9-16ALD) is a trail pheromone component ofIridomyrmex humilis, and that the true trail pheromone may be multicomponent. Trail-following responses ofI. humilis workers to several concentrations of syntheticZ9-16ALD, a constituent of the Pavan's gland, were found to be comparable to responses to gaster extract trails containing ca. 100 times lessZ9-16ALD. Of the five aldehyde analogs tested, only (Z)-7-hexadecenal (Z7-16ALD) elicited significant trail-following. However, following responses to severalZ9-16ALD-Z7-16ALD combinations were lower than responses toZ9-16ALD alone. Trails on filter paper of biologically relevant concentrations ofZ9-16ALD lose activity within 2 hr in the laboratory. The release rate ofZ9-16ALD measured from filter paper trails was 0.25 ± 0.10 pg/cm-sec. This was used to estimate the trail-following threshold for this compound of Argentine ant workers.     

Analysis of junction temperatures in high-power GaN-based LEDs

We presented the analysis of the incomplete conduction in bonding medium in high power GaN-based light-emitting diode (LED) packages. A numerical study was carried out with parametric model to understand the junction temperature variation due to bonding medium defects. Transient thermal measurement was performed to evaluate LED’s junction temperature. Thermal resistance from chip to lead frame was 20 K/W in our sample LED. It was suggested that only 60% of the surface area of the bonding medium was involved...     

Preparation of micro-patterned surfaces of Si-N-O films and their influence on adhesion behavior of endothelial cells

Microgrooves were prepared on Si(100) surface by photolithography and wet etching.Subsequently,Si-N-O films were deposited on the microgrooves by unbalanced magnetron sputtering(UBMS) and micro-patterned surfaces of Si-N-O films were obtained.The size of the micropatterns was measured by surface profilometer.The chemical composition of Si-N-O films were characterized by X-ray photoelectron spectrometry(XPS) and the wettability of the micropatterned surfaces was evaluated by contact angle measurement.The beh...     

A novel shaft-less double suction mini pump

A novel double suction shaft-less mini pump was developed for heat control of small energy systems in this study.The mini pump impeller with an exit diameter of 40 mm was combined with the motor rotor supported by the hybrid dynamic bearing.The specific speed of the pump was 125 min-1 m3 min-1 m.The hydraulic performance of the pump was investigated experimen-tally under four rotational speeds.From the test results,it was recognized that the pump could provide a flow discharge of 5 L/min and head of 1.5 m,w...