湖北省巴东县孔包汉墓发掘报告

20 0 2年底中山大学人类学系对湖北省巴东县沿渡河镇孔包汉墓进行抢救性发掘 ,共发现并清理三座凸字形券顶石室东汉晚期墓葬 ,均为多人单室家族合葬墓。出土大型陶质容器、铜镜、带钩、铜钱、手镯、指环、等 40余件 (组 )

湖北省巴东县孔包汉墓人骨鉴定

2 0 0 2年底 ,中山大学人类学系在湖北省巴东县沿渡河镇孔包村对三座东汉晚期石室墓进行了发掘。考古人员采集了墓室内的全部牙齿和尚未变成粉状的四肢长骨残段。 2 0 0 3年

Preparation and electrochemical lithium storage performance of porous silicon microsphere composite with metal modification and carbon coating

This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.

Preparation and properties of porous silicon carbide ceramics through coat-mix and composite additives process

The core-shell structure silicon-resin precursor powders were synthesized through coat-mix process and addition of Al2O3-SiO2-Y2O3 composite additives.A series of porous silicon carbide ceramics were produced after molding,carbonization and sintering.The phase,morphology,porosity,thermal conductivity,thermal expansion coefficient,and thermal shock resistance were analyzed.The results show that porous silicon carbide ceramics can be produced at low temperature.The grain size of porous silicon carbide ceramic is small,and the thermal conductivity is enhanced significantly.Composite additives also improve the thermal shock resistance of porous ceramics.The bending strength loss rate after 30 times of thermal shock test of the porous ceramics which were added Al2O3-SiO2-Y2O3 and sintered at 1 650 ℃ is only 6.5%.Moreover,the pore inside of the sample is smooth,and the pore size distribution is uniform.Composite additives make little effect on the thermal expansion coefficient of the porous silicon carbide ceramics.

Analyzing the mid-low porosity sandstone dry frame in central Sichuan based on effective medium theory

Tight gas sandstone reservoirs in Guang＇an are characterized by wide distribution and low abundance. Sandstone samples from this area usually have low porosity and poor connectivity. We analyze the observed velocity data of tight sandstone samples with the Mori- Tanaka model, and give the sandstone framework physical model in this area based on theory and experiment analysis. The matrix modulus was obtained by an empirical relationship and then the experiment data were compared with the values predicted by the Mori-Tanaka model with different pore shapes. The results revealed that the experiment data were close to the model with low pore aspect ratio. Considering the matrix modulus and pore shape variation, we find that, under the condition of small mineral composition change, the effective pore aspect ratio of these samples increased with porosity evidently.

Talc-Based Concrete for Sealing Borehole Optimized by Using Particle Packing Theory

The paper describes assessment of the performance of cement-poor concretes on the basis of packing theory. The concretes are intended for sealing segments of deep boreholes and have a small amount of cement for minimizing the mutual chemical impact on the contacting clay seals. The composition is examined by application of packing theory with respect to the cement/aggregate ratio and the gradation of the aggregate material which is crushed quartzite for providing high internal friction after maturation, as well as to talc added for fluidity and to the small amount of cement. Low porosity and micro-structural stability must be guaranteed for very long periods of time. The study exemplifies how packing theory assist designers in selecting optimal proportions of the various components. Optimum particle packing implies minimizing the porosity and thereby reducing the amount of cement paste needed to fill the voids between the aggregate particles. The use of talc as inorganic super-plasticizer since ordinary organic additives for reaching high fluidity at casting are undesirable, and since talc reacts with cement and provides high strength in along-term perspective.

The grain grading model and prediction of deleterious porosity of cement-based materials

The calculating model for the packing degree of spherical particles system was modified. The grain grading model of cement-based materials was established and could be applied in the global grading system as well as in the nano-fiber reinforced system. According to the grain grading model, two kinds of mortar were designed by using the global grain materials and nano-fiber materials such as fly ash, silica fume and NR powder. In this paper, the densities of two above systems cured for 90d were tested and the relationship of deleterious porosity and the total porosity of hardened mortar was discussed. Research results show that nano-fiber material such as NR powder can increase the density of cement-based materials. The relationship of deleterious porosity and the total porosity of hardened mortar accords with logarithmic curve. The deleterious porosity and the rationality of the grading can be roughly predicted through calculating the packing degree by the grain grading model of cement-based materials.

A Layer-Structured Metal-Organic Framework-Derived Mesoporous Carbon for Efficient Oxygen Reduction Reaction

Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.

多模态影像融合在颅底肿瘤的诊断、治疗中的应用价值

目的探讨多模态影像融合在颅底肿瘤的诊断、治疗中的应用价值。方法 9例颅底肿瘤术前均行DynaCTA检查及MRI薄层(2 mm)增强扫描检查,将多组影像数据输入工作站,采用"双容积重建"技术进行脑血管及MRI的影像融合,通过静态及动态融合影像观察肿瘤与脑结构、血管及颅骨的毗邻关系,并对肿瘤的诊断、手术治疗及预防血管并发症进行分析。结果 9例均获得满意的影像融合、具有很好的空间一致性,在一张影像上可以清晰显示病变及其周围脑结构、血管及颅骨解剖关系,提高精准性诊断,并应用于指导治疗策略、设计手术划及预防并发症。9例均恢复满意出院。结论多模态影像融合对提高颅底肿瘤的诊断精准性、提高肿瘤全切除率、降低病死率和残疾率效果肯定,对血管损伤并发症治疗疗效肯定。

Porous zinc(Ⅱ)-organic framework with potential open metal sites:Synthesis,structure and property

Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystallographic structural analysis reveals that complex 1 is a 3D porous framework containing a potential open metal site inside the pores.Topology analysis confirms that complex 1 is a two-fold interpenetrated(10,3)-b net with both metal ion and ligand acting as 3-connecting nodes.The thermal stability,variable temperature X-ray diffraction pattern and N2 adsorption property of the complex are investigated.

Phase-field modeling of void evolution and swelling in materials under irradiation

Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume change in irradiated materials. Important material processes, including the generation of defects such as vacancies and self-interstitials, their diffusion and annihilation, and void nucleation and evolution, have been taken into account in this model. The thermodynamic and kinetic properties, such as chemical free energy, interfacial energy, vacancy mobility, and annihilation rate of vacancies and interstitials, are expressed as a function of temperature and/or defect concentrations in a general manner. The model allows for parametric studies of critical void nucleus size, void growth kinetics, and void volume fraction evolutions. Our simulations demonstrated that void swelling displays a quasi-bell shape distribution with temperature often observed in experiments.

Carbon coated Au/TiO_2 mesoporous microspheres: a novel selective photocatalyst

Photocatalysts with desirable selectivity to transformation and purification of targeted pollutants are of great importance in water purification. Here, we demonstrate that selective photocatalysis can be realized by the assistance of gold-enhanced selective adsorption onto carbon-coated Au/TiO2 mesoporous microspheres （Au/TiO2@C-MM）, which were prepared via a surfactant-assisted two-step method that involved the assembly of oleic acid-stabilized titania and gold nanoparticles into colloidal spheres in an emulsion using sodium dodecyl sulfate as a surfactant and the conversion of the surfactants into carbon under annealing in Ar. Due to the negatively charged amorphous carbon, the mesoporous structure, and the surface plasmon resonance absorption of the Au components, the Au/TiO2@C-MM shows enhanced charge- and size-selective adsorption prop- erties, which enables the materials to have high selectivity in the photocatalytic process.