离散数学实践教学研究与实践

本文从算法描述、实验课程体系建设、实际应用领域介绍以及实践教学模式等方面讨论了离散数学的实践教学。     

第二代超分子主体化合物环糊精化学研究的新进展

简要介绍了环糊精化学的产生、发展及应用,重点介绍了:(1)环糊精衍生物的自组装、包合及应用;(2)新型环糊精超分子聚集体的形成及应用;(3)环糊精的包合作用在医药学研究中的应用。并对环糊精化学的发展进行了展望。     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

Influence of Extrusion Speed on the Microstructure Evolution,Interface Bonding and Mechanical Response of Mg MB26/Al 7075 Composite Rod

The Mg MB26/Al 7075 composite rod,in which Mg MB26 serves as the sleeve and Al 7075 serves as the core,is fabricated via the process of co-extrusion.The influence of extrusion speed on the microstructure evolution,interface bonding and mechanical response of the Mg MB26/Al 7075 composite rod is investigated.The results show that the typical extrusion texture of Mg sleeve does not change during co-extrusion;however,the average grain size in the Mg sleeve slightly changes from 1.57 lm in the case of extrusion speed of 0.3 mm/s to 2.78 lm in the case of extrusion speed of2.1 mm/s.The thickness of interface transition layer increases significantly from 5.5 to 50 lm,and therefore,the interface bonding becomes deteriorative with increasing extrusion speed;in particular,many cavities emerge in the case of 1.2 and2.1 mm/s.     

ADSN多传感器定位的古民居自动绘图体系

便携快捷的无损绘图是ADSN(Ancient Dwellings Sensor Network)的重要功能。通过ADSN携带定位传感器与节点通信RSSI功能,完成对不同角色节点之间精确定位与测距,形成距离可知的拓扑。 RSSI信号散度测距与红外传感器的点到点精度定位校正近距离RSSI精度,与远程超声点对点精确测距形成远程RSSI校正,通过测距拟合使得RSSI测距在50米范围达到10CM的精度。通过部署功能性节点(ID)完成对民居的功能性区域采样,形成对不同功能区域定位;形成拓扑后,使用标准功能图样库进行匹配与修正,完成对古民居的实景绘图。实际应用证明了方法的实用性。     

化学工业中的新课题——绿色化学

绿色化学是从源头上防止污染的化学。通过现存环境治理的局限性和绿色化学在环境友好方面的巨大作用和潜力的介绍 ,导出绿色化学取代传统化学的必然性。     

Wetting and evaporation behaviors of molten Mg–Al alloy drops on partially oxidized α-SiC substrates

The wetting and evaporation behaviors of Mg–Al alloys over a full composition range on partially oxidized polycrystalline α-SiC substrates were studied in a flowing Ar atmosphere using an improved sessile drop method. The time dependence of the changes in contact angle and drop geometry was monitored and representative wetting stages were identified. The initial contact angles at 1173 K were 100° for pure Al and 76° for pure Mg, with the maximum value of 106° for the 7.6 mol.% Mg–Al alloy. The interfacial reaction and the evaporation of Mg led to the decrease in the apparent contact angle in the spreading stage and their respective contribution was evaluated. After the pinning of the triple line, the decrease in the contact angle resulted from the diminishing drop volume as a consequence of the Mg evaporation. The effects of Mg concentration on the wetting and evaporation behaviors were discussed. A mechanism for the time-dependent diminishing drop volume was proposed in light of the competition between the Mg evaporation and its diffusion from the drop bulk to the surface. Finally, the interfacial reaction was analyzed based on thermodynamic considerations.     

2，2-二甲基丙酸的应用及合成条件研究

2,2-二甲基丙酸是非常重要的化工原料和化学试剂,也是有机合成重要的原料和中间体,具有很高的工业应用价值,它的合成受到了国内外研究者的重视.研究在浓硫酸的作用下,通过异丁醇和甲酸为原料来制备2,2-二甲基丙酸,并确立了最佳工艺条件,即:反应温度控制在30℃-35℃之间,反应时间为3h,原料配比为:异丁醇:甲酸:硫酸=l:1.3:6(摩尔比).2,2-二甲基丙酸的收率可达87.5%,该工艺反应时间短,产率高,经济效益高.同时又从化工工艺,农药,医药和香料方面论述了2,2-二甲基丙酸在这些领域中的应用.     

Wetting and adhesion at Mg/MgO interfaces

The wetting of (100), (110), and (111) MgO single crystals by molten Mg was studied in a flowing Ar atmosphere at 1073 K using an improved sessile drop method. The results show that the contact angle and work of adhesion are mildly dependent on MgO substrate orientation. However, the work of separation calculated by density functional theory shows a sequence of (100) < (110) < (111). This discrepancy was explained by a model considering the possible effects of evaporation and deposition of Mg at the substrate surface on the interfacial adhesion. For Mg on the clean MgO surfaces, the adhesion consists primarily of Mg–O ionic bonds with some Mg–Mg metallic bonds. In addition, a small amount of covalent bonds are present in the metal slab adjacent to the Mg/MgO (110) and Mg/MgO (111) interfaces. The different work of separation at three interfaces depends on the strength and amounts of Mg–O and Mg–Mg bonds as well as on the surface free energy of respective planes. For the MgO surfaces pre-deposited by a monolayer of Mg atoms, the interfaces are dominated by the Mg–Mg bonds, thus mitigating the effect of substrate orientation on the wettability and adhesion.     

新型超分子化合物的合成自组装及应用研究的新进展

简要介绍了超分子化学的定义、概念、产生及应用,详细介绍了:①新型超分子化合物合成及自组装;②新型超分子化合物的合成及选择性识别作用;③超分子冠醚金属配合物的合成及应用。