PDDA修饰纳米纤维素负载Pt复合物的制备及表征

以聚二甲基二烯丙基氯化铵修饰纳米纤维素(PDDA-CNCs)为载体,采用原位还原法在PDDA-CNCs载体上原位沉积Pt纳米粒子制备Pt/PDDA-CNCs复合物.利用X射线光电子能谱、Zeta电位、红外光谱、透射电镜和X射线衍射等测试方法对所制备样品的表面性质、形貌及晶型进行表征.分析结果表明,PDDA成功修饰到CNCs表明,Pt纳米粒子粒径均一且在PDDA-CNCs载体上分散性良好.     

Au/Cu_(1.94)S/ZnS纳米复合物的制备及其光催化性能研究

在油胺中合成Cu1.94S/ZnS,并将其分散到乙醇溶液中在磁力搅拌下与金纳米粒子复合,制备了Au/Cu1.94S/ZnS三元纳米复合物,利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、紫外可见分光光度计(UV-Vis)等分析测试手段对所得产物进行表征,考察了在可见光下Au/Cu1.94S/ZnS纳米复合物对染料RhB的光催化降解性质.结果显示:Au/Cu1.94S/ZnS纳米复合物具有优异的光降解性能.     

ZnS/PVA纳米复合薄膜的制备及其非线性三光子吸收研究

采用原位复合的方法制备出厚度为20μm的聚乙烯醇(PVA)与ZnS纳米微粒复合的薄膜,利用透射电镜(TEM)和X射线衍射(XRD)研究薄膜样品的微结构性能,证明已制备出立方晶相的针状ZnS纳米晶.用Z-扫描技术研究ZnS/PVA纳米复合薄膜的非线性光学性质,发现该薄膜对532 nm纳秒脉冲激光表现出较强的非线性吸收效应,而且非线性吸收强度随入射光强的增加而减少.该非线性吸收主要由纳米ZnS的三光子吸收引起,并伴随弱饱和吸收现象发生.     

ZnS纳米材料的光致发光和光催化性能

利用水热法制备ZnS纳米材料,通过X射线衍射(XRD)、扫描电子显微镜术(SEM)、光致发光(PL)对ZnS的结构及其物理性质进行研究,同时探讨退火对样品性能的影响.通过光谱分析发现,在400～650 nm附近有525 nm左右的绿光发射峰,该峰峰强随ZnS前驱体溶液中n(Zn(CH3COO)2)/n((NH2)2CS)的增加而明显减弱,从不同比例样品的对比可以得出525 nm处的绿光发射峰是由ZnS纳米结构中的锌空位而引起.制备的ZnS纳米颗粒有良好的光催化效果.对样品进行高温退火处理,发现样品退火后结晶度升高,PL绿光发射峰峰强明显降低,催化性能也从50%上升到70%,说明高温退火能有效修复ZnS纳米颗粒在制备过程中由于浓度不均而引起的锌空位.     

两种不同形貌的ZnO纳米粒子的制备和光学性质研究

以Zn(NO3)2·6H2O为原料,聚乙二醇(PEG)为结构导向剂,通过改变沉淀剂KOH的用量,制备了花瓣状和海胆状ZnO纳米粒子,用X射线衍射仪(XRD)、X射线能量扩散光谱仪(EDS)、透射电子显微镜(TEM)、高分辨扫描电子显微镜(HRSEM)对样品进行表征,研究了样品的激光拉曼散射光谱(Raman)、光致发光(PL)性质.结果表明,两种不同形貌的ZnO纳米粒子具有不同的光学活性.     

磁性聚苯乙烯微球的合成与表征

采用化学共沉淀法制备Fe3O4纳米粒子,并用聚乙二醇-6000对其表面改性,然后以苯乙烯(St)为单体,过氧化苯甲酰(BPO)为引发剂,采用分散聚合法,制备粒径小,磁含量高的磁性聚苯乙烯微球.X射线衍射(XRD)研究表明,所制备的Fe3O4粒子为面心立方结构.红外光谱测试(FT-IR)表明微球中存在苯乙烯和Fe3O4纳米粒子.透射电镜(TEM)观察表明,所制备的磁性聚苯乙烯微球的粒径约为100 nm.热重(TG)分析得到磁性聚苯乙烯微球磁性物质质量分数为14.5%.振动样品磁强计(VSM)测试结果表明,磁性聚苯乙烯纳米粒子的比饱和磁化强度为14.4 A·m2/kg,具有超顺磁性.     

电喷湿法制备二醋酸纤维素/硫化锌复合纳米粒子

二醋酸纤维素(CDA)/硫化铵((NH4)2S)复合溶液以丙酮为溶剂,在高压静电场力的作用下,喷射到对应的接收溶液ZnSO4中,通过水洗得到粒径分布比较均匀的CDA/ZnS复合纳米粒子.借助光学显微镜及扫描电镜(SEM)观察CDA/ZnS复合纳米粒子的微观形态,CDA质量分数大小较(NH4)2S质量分数对复合粒子粒径影响更大.利用透射电镜(TEM)观察发现ZnS被包覆在有机载体CDA小球中,尺寸大约为5～30nm.对试验产物进行X射线衍射(XRD)表征,证明产物同时含有CDA及ZnS.     

ZnS:Mn纳米晶的微结构和发光性能

以Na2S·9H2O为硫源,柠檬酸为稳定剂,采用溶剂热法制备了ZnS:Mn纳米晶.通过X射线衍射谱.拉曼光谱和光致发光谱分别研究了ZnS:Mn纳米晶的微结构和发光性能.结果表明:所制备的ZnS:Mn纳米晶均具有立方结构,颗粒尺寸约为2～4nm.掺杂Mn2+替代Zn2+处在置换状态.光致发光谱测试表明纯ZnS纳米晶仅存在...     

Zn1-xMnxS 纳米颗粒的制备及发光性质

水热法制备Mn离子掺杂的ZnS(ZnS∶Mn)纳米颗粒,研究不同比例掺杂Mn离子对Zn_(1-x)Mn_xS纳米颗粒光致发光性质的影响.通过X射线衍射(XRD)和透射电子显微镜(TEM)对样品的物相和形貌进行分析表征,结果显示Zn1-xMnxS(x=0、0.01、0.03、0.05、0.07、0.10)为六方纤锌矿结构的球形纳米晶,晶粒大小均匀,粒径在15~20nm之间.室温下,用350nm波长的紫外光激发Zn1-xMnxS纳米粒子,可以得到浅施主能级与锰t2能级之间的跃迁产生的蓝色发光,发光强度随锰掺杂量的增大先增强后减弱,发射峰位随锰掺杂量的变化有一定移动.究其原因可能与硫空位有关,硫空位影响ZnS的浅施主能级,锌锰比对硫空位的数量和能级位置有一定影响.     

微乳液法制备纳米二氧化硅

制备 OP-10/正辛醇/环己烷/氨水微乳液.在该微乳液中,由正硅酸乙酯在碱性条件下受控水解反应制备了 SiO2纳米粒子.通过红外光谱(FT-IR)、X射线衍射(XRD)、透射电镜(TEM)分别对样品结构及形貌尺寸进行了表征.探讨了水与表面活性剂摩尔比(R)、水与正硅酸乙酯摩尔比(H)对SiO2纳米粒子粒径的影响.结果表明制备的SiO2粒子为无定型球形颗粒,粒径为 80～105nm,SiO2纳米粒子粒径随着R和H的增大而增大.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the