NiO-WO3纳米立方块的制备及在甲醛检测中的应用

采用一步水热合成法合成NiO-WO₃纳米立方块,以WO₃为主体,引入p型半导体NiO构建NiO-WO₃ p-n异质结。通过扫描电子显微镜(SEM)和X射线衍射仪(XRD)对相应的微观结构进行了分析表征,表明产物为单斜相WO₃,由尺寸大小均匀的纳米立方块组成,平均粒径100 nm左右,引入NiO后WO₃纳米立方块的形貌基本保持不变。 将NiO-WO₃纳米立方块制成气敏元件并测验了其对甲醛气体的敏感特性。 气敏测试结果表明,构建NiO-WO₃异质结可显著地提高WO₃传感器对甲醛气体的敏感特性。 特别是5％NiO-WO₃异质结纳米立方块结构传感器,其在200 ℃下对0.134 mg/L甲醛的灵敏度达到18.5,且具有快速响应-恢复特性、良好的稳定性及对甲醛的良好选择性。 传感器性能提升的原因主是界面处p-n异质结的形成和NiO的高催化活性。     

Epitaxial Growth and Characteristics of Nonpolar a-Plane InGaN Films with Blue-Green-Red Emission and Entire In Content Range

Nonpolar （11■0） plane In_xGa_1-x N epilayers comprising the entire In content （x） range were successfully grown on nanoscale Ga N islands by metal-organic chemical vapor deposition.The structural and optical properties were studied intensively.It was found that the surface morphology was gradually smoothed when x increased from 0.06 to 0.33,even though the crystalline quality was gradually declined,which was accompanied by the appearance of phase separation in the In_x      

Effect of coating thickness on the calibration and measurement uncertainty of a wide-band liquid crystal thermography

<正>The liquid crystal thermography is a high-resolution and non-intrusive optical technique for full-field temperature measurement.We present detailed calibration data for a wide-bandwidth thermochromic liquid crystal(TLC) to investigate the effect of the coating thickness on the hue-temperature characteristics and the measurement uncertainty of the TLC.It is found that the coating thickness has appreciable effect on the TLC hue-temperature curve.For TLC coatings with the thickness over 20μm,a thicker TLC coating shows a relatively smaller measurement uncertainty,but the effect of the coating thickness is non-distinctive on the measurement uncertainty.     

区间值不确定推理真值传播的计算方法

通过用方差定义左右修正量,将点值不确定推理真值传播计算方法推广到区间值情形,提出了一种区间值不确定推理真值传播计算方法.本文所提出的方法表达式简单,易于理解与计算.     

环GR(4,2)上一类负循环码的Gray象

研究了GR(4,2)上长为2~s的负循环码的Gray象,证明了GR(4,2)上长为2~s的负循环码的Gray象是F_4上长为2~(s+2)指数为2的准循环码.通过计算GR(2~a,m)上长为2~s的负循环码的齐次距离,确定了GR(4,2)上长为2~s的负循环码的Gray象的汉明距离.     

甲壳素富集固相反射分光光度法测定矿样中的铁

本文研究了一种新的固相分光光度法－固相反射分光光度法。论文从理论上推导出反射吸附值ＡＲ与物质相应的浓度Ｃ的定量关系。并以甲壳素为吸附剂，以铁，邻二氮菲和十二烷基磺酸钠的缔合物为被吸附物，进行了甲壳素相的反射分光光度法研究。     

Negative and Superluminal Group Velocity Propagation with Narrow Pulse in a Coaxial Photonic Crystal

We investigate the propagation of electric signal along a spatially periodic impedance mismatched transmission line group. Anomalous dispersion is caused by the periodically mismatched impedance structure and a forbidden band appears near 8 MHz in transmission. The group velocity of the amplitude-modulated signal is augmented up to infinity, even -3.89c （c the speed of light in vacuum） in the forbidden region with the amplitude of the modulated signal increasing. When the carrier sinusoid signal is modulated in amplitude by the modulating sinusoid signal, of which the peak is superimposed with a narrow pulse at fivefold frequency, the superluminal group velocity also occurs. The experiment failed to show whether the propagation velocity of narrow pulse exceeds c or not.     

等分圓周法

分圓周為n等分,或與此有聯繫的關於作正多角形的問題,在學校裏的教科書中,構成了平面幾何作圖問題的一部份。教師教給學生的,是利用圓規和直尺,把圓周分為3、4、6等份的方法;有時還講把圓周分成10或5等份的方法,並把能否等分圓周的高斯檢驗法,介紹給學生。當準確的作圖不能做到時,教師們便介紹一種近似的利用量角器分圓周的方法,墨守着教科書的成法,他們常常僅作到這一步為止。利用幾何的方法是可以準確地分圓周為3、5、6、15、17、及257等份的,然而這裏並沒有一個統一的方法;分圓周為15等份的方法是這樣,而分圓周為5或6等份的方法又是那樣,所有的方法都得記住,這對學生有何益處呢? 正由於這樣,從學校裏畢業的人,幾乎在任何時候,誰也不用把圓周分為5、10、17等份的幾何方法,他們往往純粹只利用量角器來分圓周     

相分离高分子共混薄膜退火和准淬火的原位原子力显微镜研究

近年来,高分子共混薄膜在选择性渗透膜、生物材料、润滑剂、粘结剂、光敏电阻平板印刷、光电器件及纳米尺寸表面图案化等方面的研究日益受到重视,应用前景也十分可观,然而,由于其相容性较差,高分子共混物常发生相分离,相对于本体,表面的分子链具有更大的自由度,因此表面高分子链的热运动状态与本体有很大差别,为控制因相分离而导致的相区尺寸,人们必须同时对相分离热力学及动力学行为进行研究。     

淬火和退火对称三嵌段共聚物薄膜形貌和结构的Monte Carlo模拟

嵌段共聚物薄膜淬火形貌与初始化时嵌段共聚物熔体的状态相关,淬火得到的有序形貌有时存在缺陷,而退火则可以消除这些缺陷形成更规整的层状结构,且退火得到的嵌段共聚物分子的均方回转半径等都小于淬火得到的.与淬火比较,退火使高分子链充分松弛,增加了薄膜中有利于提高材料物理力学性能的桥键含量.不同于受限自由表面间的对称二嵌段共聚物首先在表面区域形成有序结构,三嵌段共聚物则在薄膜内部先形成有序的层状结构.