Dynamic analysis of preferential orientation of arasonite crystals in nacre from mollusk shell

Based on the scanning electron microscope （SEM） observations, it is confirmed that the nacre is composed of aragonite crystals and organic matrix with interlaced arrangement, showing ordered ＂brick-mortar＂ structure. The dynamic analysis of preferential orientation of aragonite crystals in the nacre from the abalone （Haliotis diverscolor supertexta） with different shell ages is systematically investigated using X-ray diffraction （XRD） and high resolution transmission electron microscope （HRTEM）. Experiments reveal that, in the nacre from the juvenile mollusk shell, there exist three kinds of orientations of aragonite crystals： （113）, （002） and （012）. However, along with the growing of the mollusk shell, the intensity of （012） and （113） becomes weak, and the （002） becomes the preferred crystal orientation of aragonite in the nacre from the adult mollusk shell, which means that the c axis of aragonite crystals is perpendicular to the nacreous layers. The results obtained show that the nacre possesses a highly ordered structure at the micrometer/nanometer mulUscale levels.     

The relationship between nacreous layer color and CaCO3 crystal orientation

The pearl or nacreous layer of mollusk shell is composed of CaCO₃ aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials, we analyzed the crystal orientation of nacreous layers with different color prepared from fresh water clamsHyriopsis cumingii Lea by X-ray diffraction. The results show that the crystal CaCO₃ orientation on specific plane is responsible for the color of pearl and nacreous pearl color. Supported by National Natural Science Foundation of China and Morning Sunlight Program of Wuhan City Government. Jiang Xinnong: born in 1970, Lecturer     

Dynamic analysis of preferential orientation of aragonite crystals in nacre from mollusk shell

Based on the scanning electron microscope (SEM) observations, it is confirmed that the nacre is composed of aragonite crystals and organic matrix with interlaced arrangement, showing ordered "brick-mortar" structure. The dynamic analysis of preferential orientation of aragonite crystals in the nacre from the abalone (Haliotis diverscolor supertexta) with different shell ages is systematically investigated using X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). Experiments reveal that, in the nacre from the juvenile mollusk shell, there exist three kinds of orientations of aragonite crystals: (113), (002) and (012). However, along with the growing of the mollusk shell, the intensity of (012) and (113) becomes weak, and the (002) becomes the preferred crystal orientation of aragonite in the nacre from the adult mollusk shell, which means that the c axis of aragonite crystals is perpendicular to the nacreous layers. The results obtained show that the nacre possesses a highly ordered structure at the micrometer/nanometer multiscale levels.     

珍珠母堆垛微结构的力学性能和热稳定性

一直以来,软体动物贝壳内的珍珠母因为其由文石片和片间有机基质薄层堆垛而成的微结构及其卓越的力学行为而广受关注,但对贝壳珍珠母的多级结构,尤其是其中的两级有机基质结构的力学功能研究甚少.本文通过机械载荷和温度载荷组合来研究皱纹盘鲍（Haliotis Discus Hannai）贝壳内的珍珠母的结构和力学特性关联.发现文石片层间的有机基质的热解有效降低了珍珠母堆垛微结构的强度和韧性,并在250℃时使珍珠母的层叠堆垛结构完全崩溃,此时有机基质的热解量约为1.7wt%,仅为有机基质总量的40%.而力学性能试验比较发现,珍珠母堆垛微结构的热稳定远低于其基本组成单元——文石片纳米复合结构.另外,尽管有机基质薄层的黏着作用对珍珠母的力学性能具有积极意义,但珍珠母微结构本身的逐层交错堆垛设计机制是影响其刚度的决定性因素.     

Petrographic and geochemical characterization of seep carbonate from Alaminos Canyon,Gulf of Mexico

Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral （98%）. Peloids, clotted microfabirc and botryoidal aragonite are developed in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ^13C value of bioclasts in carbonate is from -4.9‰ to -0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ^13C value from -31.3‰ to -23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. ^14C analyses give the radiocarbon age of about 10 ka. Rare earth elements （REE） analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g^-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.     

微细针状碳酸钙的超重力法制备及表征

采用超重力反应结晶法,在旋转填充床(RPB)反应器中,以Ca(OH)2/CO2为反应物系,MgCl2作为晶形控制剂,在较短时间(约1h)内合成出了平均短轴为80～200nm、长径比为12～20且短轴及长径比分布较窄的微细针状碳酸钙;利用TEM、电子衍射、XRD、TG-DTA等手段对产品进行了表征.XRD分析表明,所制备微细针状碳酸钙为结晶态,含有文石及方解石两种晶型,文石相含量为73%.TG-DTA分析显示,所制备的微细针状碳酸钙起始分解温度为528℃,比重力场中合成的CaCO3分解温度降低了297℃.     

富含羧基的多肽基双亲水杂化共聚物控制碳酸钙的形成

结合N-羧基-环内酸酐开环聚合和"巯-炔"光点击反应制备了侧链富含羧基的多肽基双亲水杂化共聚物(PEO-b-PPLG-g-MPA)。该多肽基共聚物可以模拟蛋白质指导CaCO3在水溶液中的形成。圆二色谱(CD)揭示了多肽链段在水溶液中的构象变化;扫描电子显微镜(SEM)揭示了矿化过程中CaCO3的形貌变化;X-射线衍射(XRD)确认了CaCO3的晶型。结果表明,该聚合物可以有效地控制CaCO3的形貌,此时多肽链段呈无规线团构象,而不是更为有序的α-螺旋或β-折叠构象;多肽链段的含量只有达到足够的浓度时,才能有效地控制的CaCO3晶体的生长;CaCO3的形貌则可以通过调节多肽链段的长度、溶液的pH值等因素进行调控,其可以是表面光滑的微球、表面堆满了CaCO3小颗粒的超结构微球、纳米棒或呈"花瓣状"聚集的纳米棒。XRD则证明形成的CaCO3呈稳定的方解石晶型。     

Scalable synthesis and electrochemical performance of mesoporous graphene from calcium carbonate by magnesiothermic reaction

A novel scalable synthetic method of mesoporous graphene has been developed using the compressed mixture of Mg and excess CaCO₃ in a closed container. The generated solid oxide and unreacted CaCO₃ could act as mesopore-forming agents, and the closed container could prevent the carbon dioxide from CaCO₃ flow away. As a result, the graphenes with a large number of 2–30 ?nm mesopores and high utilization ratio of Mg achieved. The graphenes had high specific surface area and excellent electrochemical performance. In particular, the Mg utilization ratio was up to 53.3% in the preparation of graphene using 2:1 CaCO₃/Mg at 700 ?°C, which is superior to previous researches. The obtained mesoporous graphene exhibited high specific surface area of 743.7 ?m² ?g^-1, large specific capacitance of 140 ?F ?g^-1, and high capacitance retention rate of 64.3%.     

Synthesis of self-assembled needle-shaped calcium carbonate superstructures

Novel self-assembled calcium carbonate (CaCO₃) crystals exhibiting the morphology of well-defined needles were synthesized by a simple precipitation reaction in the presence of octadecyl dihydrogen phosphate (ODP) as a crystal additive. The CaCO₃ obtained by this method is hydrophobic, making it likely to be used widely in industry. The resulting products were characterized by powder X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle experiments. The results indicated that ODP plays an important role in determining the structure, morphology and hydrophobicity of CaCO₃ crystals.     

CaCO<Subscript>3</Subscript> film synthesis from ladle furnace slag: morphological change,new material properties,and Ca extraction efficiency

A rapidly air-cooled ladle furnace slag (RA-LFS), which is a type of steelmaking slag discharged from a steel mill, was used to synthesize CaCO₃ film. The CaCO₃ film with 35 cm2 of surface area was synthesized under atmospheric conditions, and the surface morphology of the CaCO₃ films was changed by using additives (CaCl₂ and ethylene glycol). Especially, the addition of CaCl₂ changed the surface morphology of CaCO₃ film with pore and induced new material properties, such as water adsorption. The (012) face of CaCO₃ film (calcite) was rapidly decreased by the addition of CaCl₂. The major components of RA-LFS were calcium (type of CaO, 53.9wt%) and aluminum (type of Al₂O₃, 37.9wt%), and the major crystal phases of RA-LFS were C₃S, C₁₂A₇, and C₃A. The calcium extraction efficiency of RA-LFS was significantly increased after the CaCO₃ film synthesis. The material properties (hardness and elastic modulus) and the thermal characteristics of the CaCO₃ films were analyzed by nano-indentation and thermogravimetry-differential thermal analysis. The synthesized CaCO₃ films from RA-LFS and Ca(OH)₂ (reagent) showed similarities in terms of their material properties and the decomposition temperature.     

Preparation and characterization of porous ceramics prepared by kaolinite gangue and Al(OH)<Subscript>3</Subscript> with double addition of MgCO<Subscript>3</Subscript> and CaCO<Subscript>3</Subscript>

Porous ceramics were prepared from kaolinite gangue and Al(OH)₃ with double addition of MgCO₃ and CaCO₃ by the pore-forming in-situ technique. The characterizations of porous ceramics were investigated by X-ray diffractometry, scanning electron microscopy, and mercury porosimetry measurements, etc. It is found that although the decomposition of MgCO₃ and CaCO₃ has little contribution to the porosity, the double addition of MgCO₃ and CaCO₃ strongly affects the formation of liquid phase, and then changes the phase compositions, pore characterization, and strength. The appropriate mode is the sample containing 1.17wt% MgCO₃ and 1.17wt% CaCO₃, which has high apparent porosity (41.0%), high crushing strength (53.5 MPa), high mullite content (76wt%), and small average pore size (3.24 μm).     

广西伊岭岩岩石(CaCO3)晶体结构、德拜温度以及硬度研究

本文从微观角度研究碳酸钙矿石的晶体结构与物理性能,为碳酸钙矿石的应用提供理论依据。利用X射线衍射(XRD)技术分析广西伊岭岩岩石2个样品(A_1、A_2)的相组成及其晶体结构,并利用带能谱仪的电子显微镜(SEM/EDS)测试这2个样品的各相成分。结果表明:广西伊岭岩岩石的主要成分为CaCO_3,其中A_1样品含有少量的K~+,A_2样品含有少量Na~+。通过Rietveld全谱图拟合晶体结构精修可知,K~+替代样品A_1主要物相CaCO_3中的Ca~(2+),使其点阵参数变大,单胞体积变大。同样A_2样品中的Na~+替代了样品中CaCO_3的Ca~(2+)位置,造成A_2中的CaCO_3点阵参数变小,单胞体积变小。德拜温度近似模型计算出2个样品的德拜温度分别为318.86K、324.82K。维氏硬度测试法测试出2个样品的硬度大小分别为132.6HV、148.9HV。     

碳酸钙填充β-成核PP复合材料的力学性能

为研究β-晶对碳酸钙填充PP复合材料力学性能的影响,该文采用负载β-成核剂的纳米碳酸钙(β-CC)混合纳米碳酸钙(CC)或微米碳酸钙(WC)填充PP制备了β-PP复合材料及其PP-g-MA、POE-g-MA和EVA-g-MA作为相容剂的增容复合材料。力学性能研究结果表明,随着CC和WC用量增加,PP拉伸强度降低、模量提高;β-CC填充PP复合材料模量提高,拉伸强度变化不大。PP-g-MA增容提高填充PP复合材料拉伸强度、杨氏模量和冲击强度;POE-g-MA增容明显提高冲击强度,EVA-g-MA增容降低拉伸性能。β-CC/PP复合材料冲击强度随着β-CC用量增加而提高,β-CC/CC/PP和β-CC/WC/PP冲击强度高于CC/PP(w(CC)/w(PP)=5/95)和WC/PP(w(WC)/w(PP)=5/95)复合材料归结于高韧性β-晶形成。     

Effects of soil stoichiometry of the CaCO<Subscript>3</Subscript>/available phosphorus ratio on plant density in <Emphasis Type="Italic">Artemisia ordosica</Emphasis> communities

In soil, CaCO3 can reduce the availability of phosphorus in arid and semi-arid regions, thereby influencing plant growth. However, the effects of soil stoichiometry of the CaCO3/available phosphorus ratio (CaCO3/AP ratio) on plant density are unknown. In this study, we examined 4 Artemisia ordosica communities located in arid and semi-arid regions, and performed a pot experiment with an orthogonal design to examine the relationships between the soil CaCO3/AP ratio and plant density. The results showed that the soil stoichiometry of the CaCO3/AP ratio had a greater effect on growth of A. ordosica than either CaCO3 or AP as single factor. The influence of the soil CaCO3/AP ratio on density of A. ordosica was related to the climatic zone and the types and/or amplitudes of increases in the soil CaCO3/AP ratio. When the soil CaCO3/AP ratio was within the same amplitude and was less than 2.5, the A. ordosica density increased in the semi-arid region, whereas the density decreased with increasing soil CaCO3/AP ratios in the arid region. In the semi-arid region, when the soil CaCO3/AP ratio was within the same amplitude and the increase in the soil CaCO3 content was greater than the increase in soil AP, the A. ordosica density increased with increasing soil CaCO3/AP ratios. This means that the relationship between the soil CaCO3/AP ratio and the A. ordosica density remained the same. In the arid region, an increase in the soil CaCO3/AP ratio as a result of increased soil CaCO3 content and decreased soil AP resulted in increased density of A. ordosica. Therefore, the relationship between soil CaCO3/AP ratios and density of A. ordosica was altered by these changes in soil chemistry. Thus, the soil stoichiometry of the CaCO3/AP ratio is an important factor affecting the density of A. ordosica in arid and semi-arid regions.     

海洋物理化学因素对造礁珊瑚生长的影响

通过对现有资料的分析,研究了环境单因子改变对造礁珊瑚的影响.珊瑚礁发育受海平面控制,形成与海平面动荡相适应的功能骨架.大气CO2浓度升高易引起海水CO23-浓度下降,降低CaCO3各种矿物(文石、方解石等)饱和度,减缓造礁珊瑚石灰化过程,对珊瑚礁生态系统赖以生存的海洋环境构成严重威胁.文石海的高x(Mg)/x(Ca)值不利于古代低镁方解石质四射珊瑚的生长,而对现代文石质的六射珊瑚有利.富营养化水体易诱发共生藻游离出珊瑚宿主,造成珊瑚白化甚至死亡.     

两种斜翅管表面碳酸钙垢初始阶段结垢特性

进行了3种强化管在不同碳酸钙溶液浓度和流速下的动态结垢实验,得到碳酸钙浓度、流速和不同管型对碳酸钙析晶垢结垢过程的影响.结果表明,碳酸钙浓度增大,使溶液中均相成核速率和所形成晶核的生长速率增大,使溶液换热表面界面的污垢晶粒浓度和成垢离子浓度均增大,前者使更多的污垢附着换热面,而后者使表面异相成核速率和生长速率增大.流速增大,使光管表面形成的晶核、污垢晶体和污垢热阻均减少,而诱导期延长;使平直和锯齿斜翅管初始成核增多,但诱导期延长,而结垢量和污垢热阻减小.平直和锯齿斜翅管在清洁状态和结垢状态下均具有比光管更大的总换热系数、更小的污垢热阻,尽管结垢量略多.在相同结垢状态下,锯齿斜翅管的结垢量和污垢热阻大于平直斜翅管的,但是,其总换热系数仍大于平直斜翅管.     

碳纳米管砂浆在干湿循环-碳酸化作用下的性能研究

针对水泥基材料抗碳酸化性能的需要,探究了多壁碳纳米管对砂浆抵抗碳酸化侵蚀性能的影响.测定了不同掺量多壁碳纳米管砂浆的力学性能,测试了干湿循环-碳酸化侵蚀后的力学性能、pH值和CaCO3 含量变化,并利用XRD和SEM进行了微观表征.实验结果表明:砂浆力学强度随多壁碳纳米管的掺量增加先增大后降低,最佳掺量为0. 05% ...     

Microstructure and improved mechanical properties of ultrafine-grained Mo-12Si-8.5B (at.%) alloys with addition of ZrB2

Multi-hierarchical Mo-12Si-8.5B-x Zr B_2(x=0,0.5,1.0,1.5,2.5 wt%)alloys consisting of three ultrafine-grained(UFG,0.47–0.81μm)phases of Mo_5Si B_2(T2),Mo_3Si and Mo solid solution(α-Mo)were prepared by mechanical alloying following hot pressing.Microstructure observations showed that the intermetallic phases(Mo_3Si and T2)distributed dispersedly in the continuousα-Mo matrix associated with the homogeneously embedded nanoscaled particles(10–225 nm)in the grain interiors and at the grain boundaries.The Mo-12Si-8.5B-x Zr B_2alloys exhibited monotonically increasing compressive strength to 3.13 GPa with increasing content of Zr B_2,and the fracture toughness increased about 27%and reached at 11.5 MPa m~(1/2)at 1.0 wt%Zr B_2,rendering the Mo-12Si-8.5B-1.0 wt%Zr B_2alloy possessing the best combined mechanical properties of high strength and high toughness.The underlying reason for the superior mechanical properties of the Mo-12Si-8.5B-x Zr B_2alloys is that the dispersedly distributed nanosized particles in the UFG multi-phased-matrix can not only effectively block the dislocation motion to increase the strength but also store the dislocations to increase the strain hardening ability during mechanical deformation.     

Synthesis, crystal structure and thermal behavior of Rb(NTO) · H2O

The Rb(NTO)·H₂O crystal has been synthesized by reaction of 3-nitro-1,2,4-triazole-5-one (NTO) with Rb₂CO₃ in aqueous solution. Its crystal structure has been determined. The crystal belongs to monoclinic system. Crystal structure data: space group P2₁ / n; a = 0.633 0(1), b = 0.824 1(2), c =1.296 4(3) nm; β= 97.90(1)°; V = 0.669 9 (2) nm³ , Z = 4, D_c = 2.306 g/cm³, μ= 7.365 nm^-1, F (000) = 448. An eight coordinated compound is formed between Rb⁺ with oxygen atoms and nitrogen atoms. A layer structure is formed by coordination bonds and hydrogen bonds. The thermal decomposition mechanism of this coordination compound is discussed .     

Preparation,crystal structure and quantum chemical investigation of [Li(NTO) (H2O)]

[Li(NTO)(H₂O)₂] was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one (NTO) and lithium hydroxide. The crystal structure of [Li(NTO)(H₂O)₂] was determined by single crystal diffraction analysis. The crystal is monoclinic, space group P2₁/n with crystal parameters of a = 0.742 0(2) nm, b = 0.344 9(1) nm,c = 2.490 6(3) nm, β= 94.89(1)°, Z = 4,D _c , = 1.799 g cm⁻³,V = 0.635 nm³, μ = 1.591 cm⁻¹, F(000) = 392. The finalR is 0.051. The MNDO MO calculation shows that the coordinate bonds of title compound possess certain extent of covalent character. O₂ atom of NTO anion is bonded to Li atom; the nitro group will be lost first when NTO is decomposed.