白蜡虫马氏管胞内结晶的研究

报道了白蜡虫马氏管胞内细胞质的绝大部分为两种矿质(尿酸结晶)所占据。一种为不 规则状结晶,占结晶总量的70%,大小不一,含有尿酸及Si、P、Cl、Fe、Cu、Zn和S等矿质元素。另一种为年轮状结晶,占结晶总量的30%,其体积较大,含尿酸及Cl、Ca、Al和Cu等矿质元素,起于线粒 体。结晶颗粒不排入管腔。因胞内存在大量结晶致使白蜡马氏管形 成以贮存排泄为主,溶质-水偶连排泄方式为辅的特有排泄方式。

Thermodynamics and kinetics analysis of in-situ synthesizing AlN

AIN powders were prepared by in-situ synthesis technique. It is a reaction of binary molten Al-Mg alloys with highly pure nitrogen. It was confirmed through thermodynamics calculation that Mg element in Al-Mg alloys can decrease oxygen content in the reacting system. Thus, nitridation reaction can be performed to form AIN. Moreover, an analysis of kinetics shows that the nitridation reaction of Al-Mg alloys can be accelerated and transferred rapidly with the increment of Mg content.

催化消除NO_x复合氧化物催化剂的研究

氮的氧化物(NOx)是大气中的一种重要的污染物，是酸雨的主要来源，目前氮氧化物的无毒处理已经是国际环保研究中最关键的课题之一。本论文选择了两种复合氧化物：一种是钙钛石结构的含Cu的层状复合氧化物；另一种是以水滑石为前体经焙烧后得的复合氧化物为催化剂对它们的物化性质和对催化消除NOx的活性进行了系统的研究，得到了一些有意义的结果。第一部分：钙钛石型结构的含Cu层状复合氧化物钙钛石复合氧化物由于具有独特的物理化学性质，长期以来一直受到固态物理、固体化学和催化领域的科技工作者的重视。尤其近年来对它们在催化消除NOx反应中的活性的研究引起了催化工作者的极大兴趣，这是由于，一方面，钙钛石类复合氧化物对处理NOx的反应活性比较高，有希望取代贵金属催化剂；另一方面，探讨复合氧化物的固态物理、化学性质与处理NOx反应催化性能的关系，有利于揭示处理NOx反应的催化作用本质，为寻找高效实用的催化剂提供理论依据。本论文系统研究了三个系列含Cu钙钛石型复合氧化物的固态物理化学性质和对NO-CO反应的催化性能，并讨论了二者的关系。主要的工作和结论如下：1) 以La_2CuO_4为模型化合物研究了制备方法对它的性质的影响：用四种制备方法：柠檬酸络合爆炸法，聚乙二醇凝胶法，聚丙烯酰胺凝胶法，DTPA络合法合成了La_2CuO_4。比较了四种方法的特点，和制备方法对La_2Cu0_4的结构的影响，并对所得La_2CuO_4在NO-CO反应中的催化活性的影响进行了研究。结果发现聚乙二醇凝胶法和DTPA络合法有利于形成好的晶形，而聚乙二醇凝胶法和聚丙烯酰胺凝胶法对NO-CO反应有较好的活性，这是由于由不同制备方法得到的样品中的缺陷的种类和含量不I司所致。2) La_(1-x)Ba_xCuO_(3-λ)系列中Ba含量对它的性质的影响：用柠檬酸络合法合成了LaBa_2Cu_3O_(7-λ)，LaBaCu_2O_(5-λ)，La_2BaCu_3O_(7-λ) La_4BaCu_5O_(13-λ)及YBa_2Cu_3O_(7-λ)五种钙钛石结构的复合氧化物。XRD分析表明此系列样品均为层状ABO_3结构（分别为二，三，五层）。用XPS和O_2-TPD对样品中的氧种进行了研究，结果显示样品中存在着两种活性氧种：α氧种和β氧种。在O_2-TPD中低温脱附的是α氧种，它可归属于化学吸附氧与样品中的氧空位的浓度有关。β氧种的脱附温度较高，它归属于晶格氧。利用H_2-TPR和化学分析的手段对样品中的金属离子和活性氧的稳定性进行了表征。结果显示大量的氧空位和Cu~(3+)存在于样品中，并且它们的浓度受Ba离子浓度的影响。此系列样品对CO还原NO的活性研究表明：它们的活性远远高于结构类似的Ln_2CuO_4和Ln_2NiO_4等复合氧化物，在低于300 ℃时N0转化率已接近100％．分析结果表明Cu~(3+)和氧空位对活性起很重要的作用。Ba离子的作用是：一方面使含Cu的ABO_3结构稳定；另一方面使样品更容易吸附NO。3) La_4BaCu_5O_(13-λ)中Mn或C0逐步取代Cu对样品性质的影响合成了两系列分别由Mn或Co逐步取代Cu的样品，XRD分析表明它们仍旧是钙钛石结构。通过XPS，O_2-TPD和化学分析方法对样品中的活性氧种进行了表征，结果表明，当Mn逐步取代Cu离子时，晶格氧增加，而吸附氧开始变化较小，当Mn含量大于Cu含量时，吸附氧迅速减少。在Co取代样品的O_(1s)的XPS谱中，氧种变化较Mn取代的小，这表明Co离子对样品中的氧空位含量的影响较Mn离子的小。氧化还原性能的研究表明当Cu离子被Mn或Co离子部分取代后，Cu离子变得更容易被还原，这表明Cu-M(Mn或CO)之间发生了协同作用，使Cu离子更活泼。当Mn或Co部分取代Cu离子之后，样品对CO还原NO反应的催化活性明显提高，当取代含量达到一定程度时（即X ≥ 3），催化活性迅速降低，这表明Cu离子在反应中起着很重要的作用，经过分析我们认为反应机理如下：Cu~(3+)-O~=-Cu~(3+) + CO → Cu~(2+)-□-Cu~(2+)+CO_2 Cu~(2+)-□-Cu~(2+) → Cu~(3+)-□-Cu~(2+) Cu~(3+)-□-Cu~(2+) + NO~-Cu~(3+)-NO-Cu~(2+) 2Cu~(3+)-NO-Cu~(2+) → 2Cu~(3+)-O~=-Cu~(3+) + N_2 式中□是氧空位，Cu~(3+)-□ 是F心。掺杂部分Mn或Co后，催化活性的提高可以归属于Cu-M之间发生的协同作用使Cu离子更活泼，表征结果表明Cu-Co之间的协同作用较Cu-Mn之间的弱（这可能是由于Co，Cu之间化学性质相似），但掺杂Co的样品的活性较掺杂Mn的要高，同时我们在反应中发现，Co含量较高的样品中反应产物中N_2O比掺杂Mn的样品高出许多，因此我们认为Co离子对反应中反应中间产物N_2O的生成比Mn离子要活性。第二部分以水滑石化合物为前体的复合氧化物水滑石类化合物属于一种阴离子粘土，由带正电荷的金属氧化物／氢氧化物和层间阴离子及水分子组成。以水滑石为母体经焙烧制得的氧化物催化剂用于氧化反应的实例尚不多，且大多用于液相催化反应。最近有文献报道含Co，Cu，Ni水滑石经焙烧后对N_2O分解有很好的活性，但还没有关于此类化合物应用于NO还原和分解的文献报道。我们首次将以水滑石为母体经焙烧制得的尖晶石催化剂用于催化消除NO_x的反应中，考察和表征了变更过渡金属离子时Co-M-Al系列和Mg-M-Al系列催化剂在CO还原NO，NO吸附和NO分解反应中的活性。1) 以Mg-M-Al水滑石为前体的催化剂用共沉淀法合成了一系列Mg-M-Al水滑石（M = Cr，Fe，Mn，Co，Ni，Cu；Mg/M/A1 = 3/1/1）。XRD表征表明所有化合物均为典型的水滑石化合物。通过TG-DTA考察了焙烧对样品的结构和组成的影响。450 ℃焙烧后所有样品的XRD图中仅能发现MgO相，表明过渡金属氧化物均匀地分散在MgO-Al_2O_3中，换句话说，所得样品焙烧后是过渡金属氧化物负载在MgO-Al_2O_3载体上。H_2-TPR研究进一步证实过渡金属氧化物在载体上得到了稳定。此系列样品对C0还原N0反应活性的测定表明Mg-Al-Cu样品表现出远远高于其它样品的活性，而Mg-Al和Mg-Ni-Al在550 ℃以下对反应几乎没有活性，其它样品表现出一定的活性。2) 以Co-M-Al水滑石为前体的催化剂体系经共沉淀法合成了Co-M-Al水滑石（M = 过渡金属），经焙烧后发现样品中有尖晶石相出现。比表面研究表明，在500-700 ℃之间比表面变化较小大约在80m~2/g左右，在更高温度焙烧后比表面迅速下降。此系列样品对NO的吸附性能研究表明Co-Al，C0-Ni-Al，Co-Cr-Al，Co-Fe-Al表现出较高的吸附性能，尤其是Co-Ni-Al在100 ℃对NO表现出100％的吸附；其它样品对NO的吸附较低。用过渡金属离子中d轨道电子在吸附前后的晶体场稳定化能的变化可以很好地解释此系列样品对NO的吸附性能。对NO分解的活性测定表明Co-Ni-A1，Co-Cr-A1和Co-Al表现出了较好的活性，其中Co-Ni-Al的活性最高。其它样品在600 ℃以下几乎没有活性。分析结果表明样品对NO分解有活性的催化剂必须具备两个条件：1：对NO有较好的吸附性能；2: NO分解后产生的氧可以容易的脱附。除Co-Al外，所有样品对CO还原NO表现出很高的活性：在150 ℃即有较高的NO转化率，在180 ℃NO转化率即可达到100％。催化剂的氧化还原性能在反应中起着很重要的作用，H_2-TPR研究发现掺杂其它过渡金属后Co离子的还原温度明显降低，表明Co离子得到了活化。3) 以Co-Cu-Al水滑石为前体的样品用共沉淀法合成了一系列Co/Cu/Al含量不同的水滑石化合物，包括Co/Cu/Al分别为7/1/1，3/1/1及1/1/1和仅含Co或Cu的Co/Al = 3/1，Cu/Al = 3/1等一系列样品。XRD结果表明除Cu-Al外其它样品经焙烧后均出现了尖晶石相。Cu-Al样品经焙烧后出现了CuO相表明样品为CuO负载于Al_2O_3上。NO和CO的TPD研究表明三组份样品对NO和CO的吸附明显高于二组份样品，而且含CO量高的样品对NO和CO的吸附能力更好，表明Co起较强的作用。在三组份样品的NO-TPD脱出物中发现有N_2O和N_2，表明NO在样品表面的吸附为活化吸附。对CO还原NO反应活性的研究表明，三组份样品的活性远远高于二组份样品，且含Co量高的样品活性较高，表明在此系列样品中Co离子起决定性作用，而Cu离子起助催化作用。通过对反应中各组份含量的变化分析，我们认为反应机理如下：CO + O-Cat → CO_2 + □-Cat NO + □-Cat → NO-Cat 2(NO-Cat) → N_2O + O-Cat + □-Cat N_2O + □-Cat → N_2O-Cat N_2_O-Cat → N_2 + O-Cat 2(N_2O-Cat) → N_2 + 2(O-Cat) O-Cat是样品中的晶格氧，在Co-Al中加入其它过渡金属离子使样品中的晶格氧得到活化，因此，催化活性得到提高。用以水滑石为前体，共沉淀法和固相反应法等三种制备方法合成了一系列Co-Cu-Al催化剂，发现以水滑石为前体的样品不论是对NO，CO的吸附性能还是对NO-CO反应的催化活性都远远高于其它方法制备的样品，这可能是由于水滑石可以起到一个模版作用，使Cu, Co离子分散的更均匀，以及使催化剂表面的含氧基团丰富。

Phase separation and crystallization in a melt-spun Ti45Zr35Ni17Cu3 alloy

Structure and crystallization behavior of amorphous and quasicrystalline Ti45Zr35Ni17Cu3 alloy have been studied. DSC trace of the amorphous alloy obtained during continuous heating to 1300 K shows distinctly an exothermic peak and two endothermic peaks.

Fabrication, thermal stability and mechanical properties of novel composite hardmetals obtained by solid-state reaction and hot-pressing sintering

A novel cemented carbides (W0.7Al0.3)C-0.65-Co with different cobalt contents were prepared by solid-state reaction and hot-pressing technique. Hot-pressing technique as a novel technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared with WC-Co. The density, operate cost of the novel material were lower than WC-Co system. The novel materials were easy to process nanoscale sintering and get the rounded particles in the bulk materials. There is almost no eta-phase in the (W0.7Al0.3)C-0.65-Co cemented carbides system although the carbon deficient get the astonished 35% value.

Fabrication, thermal stability and mechanical properties of novel (W0.5Al0.5)C-0.8-Co composite prepared by mechanical alloying and hot-pressing sintering

A novel cemented carbides (W0.5Al0.5)C-0.8-Co with different cobalt contents were prepared by mechanical alloying and hot-pressing technique. Hot-pressing technique as a common technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared to WC-Co. The density, operating cost of the novel material were much lower than WC-Co. There is almost no eta-phase in the (W0.5Al0.5)C-0.8-Co cemented carbides system although the carbon deficient get the value of 20%, and successfully got the nanostructured rounded (W0.5Al0.5)C-0.8 particles.

Nanostructured novel cemented hard alloy obtained by mechanical alloying and hot-pressing sintering and its applications

A novel cemented carbides (W0.8Al0.2)C-0.7-Co with different cobalt contents were prepared by mechanical alloying and hot-pressing technique. Hot-pressing technique as a common technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared with WC-Co. The density, operate cost of the novel material were much lower than WC-Co system. The novel materials were easy to process nanoscale sintering and get the rounded particles in the bulk materials.

Preparation and transport properties of a bulk icosahedral quasicrystalline Ti45Zr35Ni17Cu3 alloy

A bulk alloy which consists of the single icosahedral quasicrystalline phase (I-phase) in Ti45Zr35Ni17CU3 alloy has been fabricated by mechanical alloying and subsequent pulse discharge sintering technique. Crystallographic structure analyses show that the bulk alloy is an I-phase. The transport properties of the bulk alloy are examined, and the results show that the room-temperature thermal conductivity is 5.347 W K-(1) m(-1), and the electrical conductivity decreases with increasing the temperature from 300 to 450K. The Seebeck coefficient is negative at the temperature range from 300 to 360K, and changes to positive from 370 to 450K. Hall effect measurements indicate the bulk I-phase alloy has a high carrier concentration. The specific heat capacity increases when the temperature increases from 280 to 324 K.

Fabrication, microstructure and mechanical properties of novel cemented hard alloy obtained by mechanical alloying and hot-pressing sintering

A novel cemented carbides alloy (W0.4Al0.6)C-0.65-Co were prepared by mechanical alloying and hot-pressing sintering in this work. Hot-pressing (HP) as a common technique was performed to fabricate the bulk bodies of the hard alloys. The hardness, bending strength, density of the novel hard alloy are also tested, and it has superior mechanical properties. The hardness of (W0.4Al0.6)C-0.65-Co hard alloy was very high, and the density, operate cost of the novel material were much lower than WC-Co, more important is the aluminum dissolving is not decrease the strength compared with the WC-Co system. There is almost no eta-phase in the (W0.4Al0.6)C-0.65-Co cemented carbides system even the carbon deficient reaches the astonishing value of 35%. This novel property will give us more choice to design and gain new materials that we needed.

Processing, microstructure and mechanical properties of W50Al50 bulk alloy obtained by mechanical alloying and hot-pressing

The Al50W50 alloy bulk bodies were fabricated by using mechanical alloying and hot-pressing in this work. The Al50W50 alloy had excellent thermal stability up to 1300 degreesC under vacuum and Its optimum microhardness, bending strength and compressive strength were 10.21 GPa, 570 MPa and 2.07 GPa, respectively.

Electrochemical properties of amorphous and icosahedral quasicrystalline Ti45Zr35Ni17Cu3 powders

Ti45Zr35Ni17Cu3 amorphous and single icosahedral quasicrystalline powders were synthesized by mechanical alloying and subsequent annealing at 855 K. Microstructure and electrochemical properties of two alloy electrodes were characterized. When the temperature was enhanced from 303 to 343 K, the maximum discharge capacities increased from 86 to 329 mAh g(-1) and 76 to 312 mAh g(-1) for the amorphous and quasicrystalline alloy electrodes, respectively. Discharge capacities of two electrodes decrease distinctly with increasing cycle number. The I-phase is stable during charge/discharge cycles, and the main factors for its discharge capacity loss are the increase of the charge-transfer resistance and the pulverization of alloy particles. Besides the factors mentioned above, the formation of TiH2 and ZrH2 hydrides is another primary reason for the discharge capacity loss of the amorphous alloy electrode.

Preparation and mechanical properties of a bulk icosahedral quasicrystalline Ti45Zr35Ni17Cu3 alloy

A bulk Ti45Zr35Ni17Cu3 alloy, which consisted of the icosahedral quasicrystalline phase, was prepared by mechanical alloying(MA) and subsequent pulse discharge sintering. Ti45Zr35Ni17Cu3 amorphous powders (with particle size < 50 mu m) were obtained after mechanical alloying for more than 150 h from the mixture of the elemental powder. The transformation temperature range from amorphous phase to the quasicrystalline phase was from 400 K to 900 K. The mechanical properties of the bulk quasicrystalline alloy have been examined at room temperature. The Vickers hardness and compressive fracture strength were 620 +/- 40 and 1030 +/- 60 MPa, respectively. The bulk quasicrystalline alloy exhibited the elastic deformation by the compressive test. The fracture mode was brittle cleavage fracture.

SURFACE TENSION AND DENSITY OF NaCl-NaF-RE2O8 MELTS

Surface tension and density of NaCl-NaF-RE2O, melts have been measured by means of maximum buble pressure and Archimedes methods. The results are expressed by two mathematic models. Mass fraction of RE2O5 in the melts from 0.0 to 0.6% and that of NaF/NaCl, 50-90%. This investigation shows that there might be com plexes in the melts. The information obtained can be used as a reference in the preparation of Al-RE alloys.

特大暴雨下油松林根系对土壤元素迁移的影响

根际是元素由土壤进入植物体的主要界面，降水对根际土壤元素的迁移有显著影响。本文用原状土柱淋滤实验装置及大型挖掘剖面壁法，定量分析了特大暴雨下不同深度土层油松林根系影响土壤元素的稳定输出通量的剖面特征，旨在探索黄土区林木根系对土壤养分生物有效性的提高途径。研究结果表明，特大降雨条件下，油松林地的元素随土层深度增加呈明显的递减规律，在农地土壤剖面中变异不明显。油松林地元素稳定输出通量的平均值显著大于无根系土壤。油松林0-30cm土壤剖面中的元素输出通量占总剖面元素输出通量的96．32％；油松林根系对常量元素K、Na、Mg、Ca、有益元素Si、微量营养元素Mn有明显稳定强化作用的土层深度范围为0-30cm，对有益元素Al和微量元素Cu、Fe有明显稳定强化作用的土层深度范围为0-45cm。

贵州喀斯特山区植物营养元素含量特征

贵州喀斯特山区是我国乃至世界喀斯特分布面积最大的片区之一，由于其生态系统的脆弱性，加之人类活动的干扰，使得该区的植被退化较为严重。文章选择该区的12 种主要植物作为研究对象，对其营养元素进行了研究。结果表明：>1 000μg·g-1 的元素有N、P、K、Ca、Mg、S，100~1 000 μg·g-1 的元素有Fe、Mn、Al，10~100 μg·g-1 的元素有Zn、Sr，<10 μg·g-1的元素为Cu、Mo，其中Mo 含量最低，仅为0.17 μg·g-1。这些元素中，Ca、P、K 元素高于所报道的陆生植物的含量范围。元素含量特点是Ca>K>Mg 型。N、P、K、Mg 元素的频数分布为正态分布，Ca、Al、Fe、Mn、Cu、Zn、Sr、S 元素为对数正态分布。变异系数大于100%的元素有Al、Fe、Mn、Sr，变异系数小于60%的元素有N、P、K、Ca、Mg、S、Cu，其中Ca 的变异系数最小，仅为11.8%。不同生境下相同植物的营养元素含量有较大的差异，石灰土上植物的N、P、K、Ca、Mg、Al、Cu、Mo 元素含量要高于黄壤上植物的。元素间的相关分析表明：P 和K、P 和Cu、Al 和Fe、Al 和Zn、Fe 和Zn 元素具有显著相关关系；N 和P、P 和Mg、K 和Al、K 和Cu、Ca 和Sr、S 和Mo 元素具有一般相关关系。