广西邕宁顶蛳山遗址出土黑色石料材质的光谱无损分析

石质材料鉴定是旧石器时代考古学研究的基础,因为石质种类会影响石器的制作技术、器物形态、工具类型,从而进一步制约遗址的石工业面貌乃至文化面貌。然而,仅从外观上对石器材质进行判定有很大的不确定性,特别是在鉴别黑曜石和玻璃陨石这类外观极其相似的天然玻璃质材料,大量案例表明人工目验的结果是不准确的,经常会出现误判的情况。因此,越来越多的研究开始借助现代科学仪器对石器材质进行鉴定。顶蛳山遗址作为岭南地区一处十分重要的石器时代遗址,为我们了解广西地区史前文化特征与内涵,探讨广西与周围地区史前文化交流提供了十分宝贵的资料。然而,对于出土在顶蛳山遗址中的大量黑色石器,发掘者们对这些石器的材质一直存疑。为了确定顶蛳山遗址出土黑色石料的材质,利用拉曼光谱、红外光谱和能量色散X射线荧光光谱(ED-XRF)等分析手段对其进行了原位无损材质鉴定。Raman分析表明,所有样品均为非晶态SiO_(2)类物质;同时样品的均在380 cm^(-1)处出现极强吸收峰,提示样品中可能含有黄铁矿。所有样品的红外光谱在1200~900 cm^(-1)处平滑且不见明显肩峰,同时在750~500 cm^(-1)处不见明显吸收峰,表明样品不含斜长石、石英等矿物,这与玻璃陨石的物相特征相吻合。ED-XRF结果表明,样品的主要成分是SiO_(2)和Al_(2)O_(3),且其碱土金属(RO)和铁含量高而碱金属含量低(R^(2)O),R^(2)O/RO小于1、K_(2)O/CaO的比值处于0.8~1.6之间,这些成分特征均与玻璃陨石相符。综合以上分析结果,可确定本文分析的石料样品均是玻璃陨石。分析结果对于进一步探讨顶蛳山遗址出土黑色石料的产地,顶蛳山遗址先民的活动范围及其与周边地区史前文化的交流与互动都具有重要参考价值。

Optimum blending of iron ore from Choghart stockpiles by using goal programming

Iron and steel industry is an important sector of Iran's economy.Choghart iron ore mine is an important iron ore producer of Iran steel industry.Phosphorous contained in the iron ore concentrates of Choghart mine has a detrimental effect on the steel making process,whereby this causes cracks to form in the refractory lining of blast furnaces.In the past,about 1.43 Mt of low-grade and 4.53 Mt of high-phosphorous materials had been transported to low grade and high phosphorous stockpiles,respectively,for future beneficiation.As a result of the progressive depletion of high-grade ore and establishment of beneficiation plant in Choghart,exploitation of these two stockpiles in this mine became an important issue.In this work,a linear goal programming(GP) model was developed in order to determine the optimum iron ore blend in terms of quality from low grade and high phosphorous stockpiles of Choghart mine.The model was solved by the SOLVER V.9 program.Results show that feeding with acceptable quality(w(Fe)≥50% and w(P)≤1.2%,mass fraction) materials can be blended from stockpiles that satisfy the needs of the Choghart processing line.

Effect of nano-hydroxyapatite/collagen composite and bone morphogenetic protein-2 on lumbar intertransverse fusion in rabbits

Objective: To investigate the effect of nano hydroxyapatite/collagen (nHA/collagen) composite as a graft extender and enhancer when combined with recombinant human bone morphogenetic protein 2 (rhBMP 2) on lumbar intertransverse fusion in rabbits. Methods: Sixty four adult female New Zealand white rabbits, aged 1 year and weighing 3.5 4.5 kg, underwent similar posterolateral intertransverse process arthrodesis and were randomly divided into 4 groups based on different grafts: autogenous cancellous bone alone (ACB group), nHA/collagen alone (HAC group), half autogenous cancellous bone and half nHA/collagen (ACB+HAC group) and nHA/collagen combined with rhBMP 2 (HAC+BMP group). The fusion masses were analyzed by manual palpation, radiography, biomechanical testing and histological examination. Results: Fusion was observed in 4 cases in the 6th week and in 5 cases in the 10th week after surgery in ACB group. No case showed fusion in HAC group. In ACB+HAC group, there was fusion in 3 cases in the 6th week and in 4 cases in the 10th week after surgery. In HAC+BMP group, fusion in 1 case was found in the 4th week, in 5 cases in the 6th week and in 6 cases in the 10th week after surgery. It suggested that ACB, ACB+HAC and HAC+BMP groups showed similar fusion ratio and mechanical strength in the 6th and 10th week after surgery. According to the microstructure analysis of the samples, nHA/collagen had no negative effect when implanted together with ilium autograft. In HAC+BMP group, new bone like tissue was observed in the 2nd week postoperatively, and nearly all of the implanted composites were replaced by mature bone matrix and new bones in 10th week postoperatively. Conclusions: The nHA/collagen, especially combined with rhBMP 2, is a promising bone substitute, for it has quick biodegradation, fine bone bending ability, and high osteoconductivity on posterolateral spinal fusion in rabbits.

Independent thickness and lateral size sorting of two-dimensional materials

Two-dimensional(2D)materials possess unique thickness-and lateral-size-dependent properties.Many efforts have been devoted to obtaining 2D materials with narrow structure heterogeneity while it is still challenging to independently control their thickness and lateral size,limiting their widespread applications.Here,we develop a three-step method which achieves independent thickness and lateral size sorting of 2D materials.Taking 2D h-BN flakes as an example,their thickness and lateral size are independently sorted to different fractions with thicknesses smaller than 6 nm.In addition,the 2D h-BN flakes possess narrow distributions of both thickness and lateral size.We further develop a force field extraction method and achieve scalable size sorting of 2D h-BN,which is universal for sorting other 2D materials including MoS2 and graphene oxide.This work reports an effective method to produce structure homogenous 2D materials and will help fundamental studies and applications of 2D materials where thickness and lateral size are of concern.

Preparation and degradation characteristic study of bone repair composite of DL-polylactic acid/hydroxyapatite/decalcifying bone matrix

To explore the preparative method an d study the degradation characteristics of bone repair composite of DL polylac tic acid (PDLLA)/hydroxyapatite(HA)/decalcifying bone matrix (DBM) in vitro. Methods: An emulsion blend method was developed to prepare the composite of PDLLA/HA/DBM in weight ratio of PDLLA:HA:DBM= 1.5 2 : 1 1.5 : 1. The dynamic changes of weight, biomechanical property and pH value of PDLLA/ HA/DBM and PDLLA in phosphate buffered saline (PBS, pH 7.4 ) were studied re spectively through degradation tests in vitro. Results: Without being heated, PDLLA, HA and DBM could be synt hesized with the emulsion blend method as bone composite of PDLLA/HA/DBM, which had both osteoconductive and osteoinductive effects. The diameter of the apertu re was 100 400 μm and the gap rate was 71.3 %. During degradation, the pH v alue of PDLLA solution decreased lightly within 2 weeks, but decreased obviously at the end of 4 weeks and the value was 4.0 . While the pH value of PDLLA/H A/DBM kept quite steady and was 6.4 at the end of 12 weeks. The weight of PDLLA changed little within 4 weeks, then changed obviously and was 50% of its initia l weight at the end of 12 weeks. While the weight of PDLLA/HA/DBM changed little within 5 weeks, then changed obviously and was 60% of the initial weight at the end of 12 weeks. The initial biomechanical strength of PDLLA was 1.33 MPa, decreased little within 3 weeks, then changed obviously and kept at 0.11 MP a at the end of 12 weeks. The initial biomechanical strength of PDLLA/HA/DBM was 1.7 MPa, decreased little within 4 weeks, then changed obviously and kept at 0.21 MPa at the end of 12 weeks. Conclusions: The emulsion blend method is a new method to prepa re bone repair materials. As a new bone repair material, PDLLA/HA/DBM is more su itable for regeneration and cell implantation, and the environment during its de gradation is advantageous to the growth of bone cells.

Graphitized nanocarbon-supported metal catalysts:synthesis,properties,and applications in heterogeneous catalysis

Graphitized nanocarbon materials can be an ideal catalyst support for heterogeneous catalytic systems. Their unique physical and chemical properties, such as large surface area, high adsorption capacity, excellent thermal and mechanical stability, outstanding electronic properties, and tunable porosity, allow the anchoring and dispersion of the active metals. Therefore, currently they are used as the key support material in many catalytic processes. This review summarizes recent relevant applications in supported catalysts that use graphitized nanocarbon as supports for catalytic oxidation, hydrogenation, dehydrogenation, and C-C coupling reactions in liquid-phase and gas-solid phase-reaction systems. The latest developments in specific features derived from the morphology and characteristics of graphitized na- nocarbon-supported metal catalysts are highlighted, as well as the differences in the catalytic behavior of graphitized nano- carbon-supported metal catalysts versus other related cata- lysts. The scientific challenges and opportunities in this field are also discussed.