煅烧温度对TiO_2粉体的微观结构及光催化特性的影响

以钛酸丁酯为原料,采用溶胶-凝胶法制备TiO2粉体。利用X射线衍射谱、拉曼光谱、红外光谱、扫描电子显微镜和紫外-可见光分光光度计分别研究煅烧温度对TiO2粉体的微观结构、颗粒形貌与紫外光光催化性能的影响。实验结果表明:随着煅烧温度的升高,TiO2粉体发生了锐钛矿到金红石结构的相变,相变温度大约在623K~673K,且等轴状颗粒的尺寸逐渐增加。同时发现锐钛矿结构的TiO2粉体对甲基橙的紫外光光催化活性最高,而无定形及金红石结构不利于粉体的紫外光光催化活性。     

钛网表面TiO2纳米管表征及光催化性能研究

采用阳极氧化的方法在钛网基体上制备了二氧钛纳米管.利用SEM、XRD、TEM和XPS对试样进行了表征,并对其紫外光光催化性能进行了测试.结果显示,以钛网为载体试样,SEM照片显示出特别的背脊结构.XRD分析表明TiO_2纳米管在热处理温度450℃与550℃之间发生了锐钛矿相向金红石相的转变.由XPS拟合分峰后表明,试样表面Ti元素存在方式有TiO_2和Ti_2O_3.经热处理TiO_2纳米管降解罗丹明B实验表明,锐钛矿与金红石混合结构较单纯锐钛矿结构光催化效率高,金红石含量存在一个最佳值.     

超细二氧化钛粉的制备

1 产品简介 二氧化钛,俗称钛白粉,英文名称Titanium oxide,分子式为TiO_2,分子量为61.90。 二氧化钛为白色或微黄色粉末,无臭、无味,其化学性质稳定,在一般条件下与大部分化学试剂不发生反应。难溶于水及其它溶剂。二氧化钛存在有三种不同的晶型:金红石型、锐钛矿型和板钛矿型。其晶型随温度呈如下变化:板钛矿→锐钛矿→金红石。二氧化钛三种晶型的主要性质见表1。     

不同酸处理钛酸锂的转型研究（英文）

详细研究了酸的种类和处理时间对钛酸锂转型的影响.结果显示当相同酸度的硫酸和盐酸用来对钛酸锂进行改性时,在盐酸介质中钛酸锂更容易转变为锐钛矿和金红石型二氧化钛.硫酸浓度越高,钛酸锂更容易转变为锐钛矿和金红石型二氧化钛;处理时间越长,更多的钛酸锂可以转变为锐钛矿和金红石型二氧化钛.硫酸根通过螯合双齿配位于二氧化钛,有利于稳定锐钛矿型晶相;亲电的H~+和高电负性的Cl~-影响Ti-O键,导致TiO_6八面体中的Ti-O键断裂和锐钛矿型二氧化钛发生结构重排形成金红石型二氧化钛.钛锂离子筛稳定的结构和晶相组成能够保证高效、循环往复地提取锂,从这一点来看,相比于盐酸,硫酸更适合作为洗脱剂来制备钛锂离子筛,并且低浓度的硫酸是更好的选择.     

纳米TiO_2晶型转化机制探讨

根据统计物理学方法推导出锐钛矿型TiO_2向金红石型TiO_2转化率关系式为InX_A=-v_0texp(-2U_x/kT),其中X_A为TiO_2中锐钛矿型的含量,v_0和U_x分别锐钛矿型TiO_2原子的振动频率和势函数,t、k和T分别为煅烧时间、玻兹曼常数和煅烧温度.TiO_2为三原子分子,理论上v_0和U_x计算十分复杂,本文通过在不同温度及时间下煅烧氨水水解TiOSO_4产物的方式制备了锐钛矿型、混晶型及金红石型纳米TiO_2粉末,将XRD分析所测数据及相应温度、时间条件代入转化率关系式,拟合求得:v_0=5.3×10~(10)/s,U_x=2.71×10~(-12)J.实验所测_A-t及X_A-T曲线与计算拟合曲线吻合较好,说明用氨水水解TiOSO_4产物的方式制备的锐钛矿型纳米TiO_2向金红石型纳米TiO_2的转化为扩散型转变.     

钕离子掺杂对TiO_2相组成和光催化活性的影响

用溶胶-凝胶法制备掺杂钕离子的TiO_2纳米粒子,并研究钕离子掺杂对TiO_2相结构和光催化活性的影响。结果表明:掺杂钕离子能抑制锐钛矿相向金红石相转变,并能抑制TiO_2晶粒长大;掺杂钕离子能提高TiO_2的光催化活性,掺杂量为0.069％时,光催化活性最高。     

金红石二氧化钛介电常数的光致增大效应

研究了紫外光照对金红石二氧化钛(TiO_2)和锐钛矿TiO_2介电性质的影响。利用阻抗分析仪,测量暗态和紫外光照下金红石TiO_2和锐钛矿TiO_2在40~106Hz的介电常数。测量结果表明:在50~400Hz,紫外光照可提高金红石TiO_2的介电常数约18%,降低介电损耗约7%。在相同光照和测量频率条件下,锐钛矿TiO_2的介电常数降低约10%。     

不同酸处理钛酸锂的转型研究

详细研究了酸的种类和处理时间对钛酸锂转型的影响. 结果显示当相同酸度的硫酸和盐酸用来对钛酸锂进行改性时,在盐酸介质中钛酸锂更容易转变为锐钛矿和金红石型二氧化钛. 硫酸浓度越高,钛酸锂更容易转变为锐钛矿和金红石型二氧化钛;处理时间越长,更多的钛酸锂可以转变为锐钛矿和金红石型二氧化钛. 硫酸根通过螯合双齿配位于二氧化钛,有利于稳定锐钛矿型晶相;亲电的H+和高电负性的Cl-影响Ti-O键,导致TiO6八面体中的Ti-O键断裂和锐钛矿型二氧化钛发生结构重排形成金红石型二氧化钛. 钛锂离子筛稳定的结构和晶相组成能够保证高效、循环往复地提取锂,从这一点来看,相比于盐酸,硫酸更适合作为洗脱剂来制备钛锂离子筛,并且低浓度的盐酸是更好的选择.     

TiO_2、Al_2O_3基燃烧催化剂的固态化学研究

研究了TiO_2烧结及相变过程的动力学、机理及载体TiO_2经Al2O_3改性后的热稳定性。考察了以纯TiO_2和改性TiO_2为载体所制催化剂的耐热性。结果表明,Tio_2的烧结为体积扩散过程,锐钛型TiO_2变为金红石型的核化-生长过程中,成核和生长的活化能分别为71kJ/mol和227kJ/mol,其中生长过程为晶界扩散。用共沉淀法在TiO_2中掺杂Al_2O_3能明显提高Tio_2的热稳定性。Cu-Mn-Ce-O/TiO_2催化剂在700℃高温处理时,催化活性反而升高,这可能与TiO_2的相变过程有关。     

减压过程中氯铅矿型TiO_2相稳定及晶体结构的第一性原理研究

利用基于密度泛函理论的GGA方法对氯铅矿型及相关的锐钛矿型和金红石型TiO_2进行了理论计算.首先,优化了这三种晶型TiO_2的晶体结构及相关参数,并计算分析了焓随压强的变化曲线,发现在减压至2.0 GPa时,氯铅矿型TiO_2直接相变为锐钛矿型.其次,通过拟合分析了三阶B-M状态方程获得它们的体弹模量B0与平衡体积V0,并与实验及其他理论计算符合的非常好.最后,我们通过比较相变前后晶体结构、体弹模量B0和平衡体积V0变化,并进一步讨论了氯铅矿型TiO_2的相变行为.同时,希望我们的结果能为相关实验研究提供一点理论参考.     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.