氮掺杂有序介孔碳-Ni纳米复合材料的制备及电化学性能

以F127为模板剂,Ni Cl2为镍源,尿素为氮源,间苯二酚甲醛原位聚合树脂为碳源,分别采用均相法和两相法制备Ni-NOMC-1,Ni-N-OMC-2纳米复合材料。X射线衍射(XRD)、激光拉曼以及透射电子显微镜(TEM)等测试结果表明,复合材料具有有序介孔结构,Ni以金属微粒形式嵌于碳骨架中,提高了有序介孔碳的石墨化程度。X射线光电子能谱测试(XPS)表明尿素热解后以4种形式存在:sp3杂化与C结合的N原子,吡啶N原子,sp2杂化与C结合的N原子以及quaternary-N原子。Ni-N的共改性改变了碳载体的理化性质,有利于Pt纳米粒子的负载与分散。均相法制备的Ni-N-OMC-1复合材料微波负载Pt后,氧还原极限电流密度为5.32 m A·cm-2,氢氧化电化学活性面积高达138.53 m2·g-1,电化学催化活性优于商业20%Pt/C材料(4.49 m A·cm-2,96.98 m2·g-1)。     

吡罗昔康在纳米Fe_3O_4-石墨烯复合修饰玻碳电极上的电化学行为及电分析研究

采用纳米Fe3O4粒子(nano-Fe3O4)和石墨烯(Reduced Graphene Oxide,RGO)制备了nano-Fe3O4-RGO复合材料修饰玻碳电极(nano-Fe3O4-RGO/GCE),采用循环伏安法(cyclic voltammetry,CV),方波伏安法(square wave voltammetry,SWV),计时电流法(chronoamperometry,CA),计时库仑法(chronocoulometry,CC)研究了吡罗昔康(Piroxicam,PC)在此复合修饰电极上的电化学行为及电化学动力学性质。实验结果表明,与GCE相比,nano-Fe3O4-RGO/GCE对PC的电化学氧化作用有显著的促进作用,其氧化峰电流显著增加;对各种实验条件进行了优化,测得峰电流Ipa与PC浓度在2.0×10-6~2.0×10-4mol·L-1范围内呈良好的线性关系,检出限(S/N=3)为5.3×10-7mol·L-1,加标回收率为100.0%~104.0%。该方法快速,灵敏,并将nano-Fe3O4-RGO/GCE用于市售吡罗昔康片剂的测定,结果符合定量测定要求。     

元素分析仪测定土壤、沉积物样品碳氮含量的影响因素及数据校正

使用元素分析仪进行土壤、沉积物样品碳、氮含量检测时,样品前处理过程(烘干和酸化)、包样质量以及参考标准品等因素均会对检测结果造成影响.试验结果表明:酸化导致氮百分质量的测定结果降低2.6%~40.0%,碳百分质量的测定受包样质量的影响较大,使用的校正标准与被测样品越相似,校正结果越准确.     

SPATIAL AND SEASONAL DISTRIBUTIONS OF ATMOSPHERIC CARBONACEOUS AEROSOLS IN PEARL RIVER DELTA REGION, CHINA

Concentrations and spatial distributions of organic carbon (OC) and elemental carbon (EC) in atmospheric particles were measured at 8 sites in four cities (Hong Kong, Guangzhou, Shenzhen and Zhuhai) of Pearl River Delta Region (PRDR), China during 2001 winter period and 2002 summer period. PM2.5 (particie diameter smaller than 2.5 um) and PM10 (particie diameter smaller than 10 um) samples were collected on pre-fired quartz filters with mini-volume samplers and analyzed using thermal optical reflectance (TOR) method. The average PM2.5and PM10 Ievel were 60.1 and 93.1 μg·m-3, respectively, with PM2.5 constituting 65.3% of the PM10 mass. The average OC and EC concentrations in PM2.5 were 12.0 and 5.1 μg·m-3, respectively, while those in PM10 were 16.0 and 6.5 μg·m-3, respectively. The carbo-naceous aerosol accounted for 37.2% of the PM2.5 and 32.8% of the PM10. The highest concentrations of OC and EC were observed at Guangzhou city in both vvinter and summer seasons. The average OC/EC ratios were 2.     

直流射频等离子体增强化学气相沉积类金刚石碳薄膜的结构及摩擦学性能研究

利用直流射频等离子增强化学气相沉积技术在单晶硅表面制备了类金刚石碳薄膜．采用Raman光谱、红外光谱、x射线光电子能谱和原子力显微镜等研究了薄膜的微观结构和表面形貌,在UMT-2MT型摩擦磨损试验机上考察了薄膜在不同载荷与滑动速度下的摩擦学性能。结果表明：所制备的类金刚石碳薄膜具有典型的类金刚石结构特征,薄膜均匀、致密,表面粗糙度小,硬度较高;薄膜与Si3N4陶瓷球对摩时显示出良好的抗磨减摩性能;随着试验载荷与滑动速度的提高,薄膜的摩擦系数降低,耐磨寿命降低;薄膜的减摩抗磨性能同其在Si3N4陶瓷球偶件磨损表面形成的转移膜相关。     

碳包覆铁纳米颗粒的气相爆轰合成北大核心CSCD

以粉末状与气态二茂铁为原料,以氢气和氧气混合气体为爆轰能源,采用气相爆轰法进行了合成碳包覆铁纳米颗粒实验。XRD和TEM实验结果表明,采用两种不同状态的二茂铁,均得到了纳米碳包覆铁颗粒。该包覆颗粒的组成核为铁或铁碳化合物,外层壳主要由石墨碳组成,大部分球形纳米颗粒尺寸分布于5-30 nm之间。通过对比发现,采用气态二茂铁爆轰时,所得到的碳包铁粒度分布较为集中,壳层厚度比较均匀,且粒子具有较好的球形状。最后结合铁碳合金相图,从热处理角度对气相爆轰合成碳包覆铁纳米颗粒的机理进行了分析,得出产物中α-Fe与Fe_3C的形成过程。分析了碳包覆铁纳米颗粒的磁滞回线,其表现出硬磁性与顺磁性双重性质。     

MD simulation for nanocrystals

Molecular dynamic (MD) provided anab initio simulation for nano-scale mechanical behavior of materials, provided that the inter-atomic potential is accurately prescribed. MD is particularly suitable in simulating the formation, the deformation, and the evolution of nanocrystals under a fast strain rate. To tackle large scale system and nano-seconds time duration, parallel algorithm is desired. The present paper reviews the recent advances in MD simulation for nanocrystals rithm is desired. The present paper reviews the recent advances in MD simulation for nanocrstals with attention focused on the applications toward nanomechanics. The examined issues are: formation of nanocrystalline metals, nanoindentation on nancorystals, fast deformation of nanocrystals, orderdisorder transition, and nano-particle impact. The project supported by the National Natural Science Foundation of China (101212202 and 90205023)     

Investigation of operational parameters for an industrial CFB combustor of coal, biomass and sludge

The combustion of coal and/or biomass （sludge, wood waste, RDF, etc.） in a circulating fluidized bed has been a commercial topper for over 20 years, and references to principles and applications are numerous and widespread although few data are presented concerning the operation of large scale CFB-units. The authors studied the CFB-combustion at UPM-Kymmene （Ayr）, a major paper mill relying for its steam production upon the combustion of coal （80-85 %）, wood bark （5-10%） and wastewater treatment sludge （5-10%）. The maximum capacity of the CFB is 58 MWth. A complete diagnostic of the operation was made, and additional tests were performed to assess the operating mode. The plant schematics, relevant dimensions and process data are given. To assess the operation of the UPM-CFB, it is important to review essential design parameters and principles of CFB combustors, which will be discussed in detail to include required data, heat balance and flowrates, operating versus transport velocity, kinetics and conversion （including the possible effect of the Bouduard reaction if carbon is present）. Since the residence time in the riser and the cyclone efficiency determine the burnout of circulating fuel-particles, the UPM-CFB was subjected to a stimulus response technique using nickel oxide as tracer. Results illustrate the efficiency of the cyclone separation and the number of recycle loops for particles of a given size. Results will also be used to assess the cyclone operation and efficiency and to comment upon expected and measured carbon conversion.     

碳钢表面碳—氮共渗层在高速干摩擦条件下的摩擦学性能研究

对 2 0 # 钢试样进行碳 -氮共渗热处理 ,考察了共渗层在高速干摩擦条件下的摩擦学性能 ,并用扫描电子显微镜和X射线光电子能谱仪对其磨损表面形貌和元素化学状态进行了分析 .结果表明 :随着滑动速度的增加 ,2 0 # 钢表面碳 -氮共渗层的磨损率逐渐降低 ,当滑动速度达到 35m/s左右时 ,磨损率显著增大 .扫描电子显微镜和X射线光电子能谱分析结果表明 ,高速轻载干摩擦条件下 2 0 # 钢表面碳 -氮共渗层的摩擦学性能同磨损表面氧化物的形成和剥落密切相关 ,而磨损率的显著增加是由于磨损表面氧化物类型发生从Fe2 O3 到FeO的转变所致 .     

《发光学报》征稿内容

<正>《发光学报》是中国物理学会发光分会、中国科学院长春光学精密机械与物理研究所主办的,以发光学、凝聚态物质中的激发态过程为专业方向的综合性学术刊物。本刊适用于凝聚态物理、光学材料合成、环境保护、化学化工、国防、医药等领域的科学研