菌液浸泡法在水泥基材料表面覆膜研究

选取一种碳酸盐矿化菌,利用其新陈代谢过程中发生的酶化反应分解底物生成CO2-3,通过适时引入Ca2+,最终在水泥石表面沉积一层致密而坚硬的碳酸钙保护层.研究了不同生长阶段的细菌和Ca2+浓度对所得碳酸钙层的物理、化学性能的影响,并通过测试毛细吸水系数表征试样表面覆膜后的抗渗效果.结果表明:细菌活性和Ca2+浓度对所沉积的碳酸钙的晶型和形貌均有很大程度的影响:经过菌液浸泡法表面覆膜的水泥石试样,其表面吸水系数大大降低,抗渗性能得到有效改善.     

MICP矿化产物中钙离子利用率的影响因素及微观物相分析

钙离子利用率是微生物诱导碳酸钙沉积矿化技术中一项重要指标和参数，待矿化钙离子能否参与到矿化反应和如何被利用是这项技术的关键。本文借助紫外线吸光度法、电导率法和EDTA滴定法等技术手段，分析了待胶结菌液浓度和脲酶活性的时变规律，阐述了不同胶结配比对矿化反应过程中钙离子利用率的影响。结果表明：在胶结过程中，细菌的浓度和脲酶活性会逐渐降低；在合理浓度范围内，钙离子利用率随菌液浓度以及胶结液浓度的增大而提高，最高可达99.73%。进而通过X射线衍射、扫描电镜检测来揭示矿化产物的形成机理，分析得出：球霰状碳酸钙晶体是钙离子在有机质的调控下依托细菌表面的成核位点富集矿化而成，矿化产物中碳酸钙晶体尺寸大小和形态受菌液和胶结液配比浓度的影响。本研究对于微生物诱导矿化反应生成碳酸钙在工程材料领域的应用具有一定的参考价值。     

碳酸根替代对磷灰石块体和涂层生物矿化的影响研究

应用体外实验方法(in vitro)研究了不同碳酸根替代量的磷灰石块体和电泳沉积涂层的生物矿化性能,通过XRD和SEM等手段分别研究了块体和电泳涂层样品的生物矿化过程.研究结果表明,碳酸根掺杂形成的磷灰石结晶程度差、晶粒尺寸小,利于块体的烧结致密及在SBF溶液中表面类骨碳酸羟基磷灰石矿化层(HCA)的形成.然而,碳酸根掺杂大大减少了涂层中气孔孔径和孔隙率,不利于矿化层的沉积生长,削弱了涂层的生物矿化性能.     

碳酸盐矿化菌株A固结土壤Cd2+的生物矿化过程

研究菌株A在Cd2 存在条件下的生物矿化行为以及所选用菌株修复Cd2 染土壤的效果.结果表明:菌株A的脲酶常数Km为1.231 mol/L,Cd2 浓度为0.595 mg/L时,菌株生长良好;随着Cd2 浓度的增加,细菌生长由促进变为抑制.细菌在Cd2 污染的水溶液和土壤中仍具有很强的酶活性.游离态Cd2 能够与细菌新陈代谢产物CO32-形成CdCO3不溶晶体沉淀.通过盆栽实验,经过菌株A对Cd2 污染土壤的处理,有效的降低土壤游离态Cd2 和植物体内Cd2 含量.在土壤、水资源处理方面,菌株A在生物矿化固结重金属有着广阔的应用前景.     

HA/TCP双相陶瓷的生物矿化研究

采用新型动态体外模拟系统对HA/TCP双相陶瓷进行了体外生物矿化性能研究,通过SEM、EDAX、FT-IR等测试手段研究并分析了模拟体液流速以及钙磷离子补充在矿化过程中对样品表面磷灰石晶体生长影响.研究发现,较低的模拟体液流速下样品表面形成针片状碳酸化羟基磷灰石晶体,而在较高的流速下,晶片交错生长,形成网状结构,将样品表面完全覆盖.同时,模拟体液Ca2+的及时补充也有助于矿化层的形成.     

水泥石表面微生物沉积碳酸钙覆膜的不同工艺

自然界中某些微生物可以通过其自身生命活动的不断精确重复在石材表面矿化覆膜.选用了一种碳酸盐矿化菌,在实验室内人为加速模拟这一微生物矿化过程,7 d内可在水泥石表面沉积出碳酸钙膜,与基材结合紧密.通过浸泡、喷涂、固载涂刷等多种工艺进行了微生物覆膜,并对覆膜层进行扫描电镜分析、厚度测量、以及覆膜后试件毛细吸水系数的对比结果发现:通过微环境的供给与优化,可以简化覆膜工艺,尤其以海藻酸钠或琼脂作为载体涂刷覆膜,其相比于喷涂法更能使菌株附着于水泥石表面生长,并在较长时间内保护菌株细胞内的酶活性.水泥石试件覆膜后毛细吸水系数可降低近90%,防护效果显著.     

生物矿化碳酸钙机理研究进展

生物矿化组织的微观分级结构主要取决于生物控制的分子过程,包括晶体生核、生长,以及矿物结构的堆积方式.生物分泌有机基质通过有机-无机界面处的晶格匹配、立体化学互补,电荷匹配等界面分子识别作用,调控着无机相的结晶过程,并最终形成了具有特定形态的晶体.本文综述了了国内外在模拟研究无机矿化作用机理方发展过程,研究现状.并指出要充分结合生物化学及基因工程来研究生物矿化的长期表达过程.     

微生物沉积碳酸钙修复水泥基材料表面缺陷

用涂刷技术,以琼脂作为载体将菌株和营养物质固载于水泥石表面,创造菌株生长、酶化和碳酸钙沉积的微环境,7 d后能在水泥石表面紧密附着生成厚度100μm左右的碳酸钙膜,其表面吸水率可以降低到覆膜前的15%以下;同时将高浓缩菌株与砂基材拌合,并混合尿素和Ca2 ,制备成浆体,注入到水泥石人造裂缝中,通过定时滴加修复营养液的方法,逐渐在裂缝砂粒之间矿化沉积出碳酸钙,最终将砂粒紧密胶结在裂缝内,达到裂缝修复的目的,28d抗压强度可恢复至84%,效果显著.通过涂抹工艺和注入工艺的实现,可在材料表面原位矿化沉积出方解石,增强了微生物修复在实际工程中应用的可操作性.     

碳酸钙生物矿化研究

文章综述了有序分子模板对碳酸钙晶体的调控研究进展.研究结果表明,通过选择合适的实验条件,可以有效调控碳酸钙晶体的晶型、形貌、尺寸,这为生物矿化机理研究提供了一些依据,同时为合成新型材料提供了方法和途径.     

氨基酸基质下碳酸钙的仿生合成

依据仿生合成的原理,以甘氨酸和酪氨酸作为有机基质,以尿素和氯化钙为原料,通过简单的水热合成法制备了碳酸钙晶体;利用XRD,SEM对产物进行表征,结果发现在不添加有机基质的溶液中得到树枝状的文石相碳酸钙晶体,添加甘氨酸溶液中得到方解石相碳酸钙,添加酪氨酸溶液中得到的方解石相和文石相碳酸钙混合晶体.并对碳酸钙晶须生长机理和两种氨基酸与碳酸钙的作用机理进行了初步探讨,氨基酸在水溶液中解离的带电荷的氨基和羧基对碳酸钙晶体成核和晶体生长起重要的作用,促进了方解石的成核生长;不同氨基酸等电点不同,R基结构不同也影响了碳酸钙晶体的最终形貌.     

Characteristics of processed shales affecting oil yield loss to coke

The objective of this research was to further examine coking during hot-solid recycle retorting. Specifically the relationship between process-induced macroporosity and the reactivity of the shale mineral matrix was investigated. Photomicrographs support a direct relation between coking and the development of macroporosity in oxidized substrates. As access to the mineral matrix increases, the effect of processing on its reactivity becomes more important. The coking activity of illite, the major mineral component of the shale used, increased slightly when heat-treated to 973 K, but further heat treatment to 1323 K decreased its reactivity. Coke deposited on combusted shale and illite either blocked access to and/or deactivated coking sites, significantly reducing substrate reactivity. Carbon removal from the illite by oxidation at 773 K increased reactivity threefold over untreated illite. Combusted shale had fewer active coking sites, as measured by temperature-programmed desorption analysis, than gasified shale. This was consistent with deactivation of the mineral matrix with increased temperature treatment. Results also indicated that deactivation of the mineral matrix was possible by heat and steam treatments. The data provided further evidence that the amount of oil yield loss to coke was primarily controlled by process-induced macroporosity, allowing access to a reactive mineral matrix.     

混凝土矿物掺合料的强度效应研究

矿物掺合料对混凝土具有重要的强度效应。本文认为掺有矿物掺合料的混凝土复合材料的强度由水泥混凝土基体（水泥浆体和砂石集料）产生的强度和帮物掺合料的物理和化学两方面效应对强度的贡献两部分构成，据此提出了全面估算混凝土矿物掺合料强度效应的新方法。并从理论和试验两方面分析了水胶化、掺合料掺量以有龄期对矿物掺合料强度效应的影响规律。     

矿物质负载方式对焦炭溶损反应的作用研究

比较了1 1种氧化物以添加和吸附两种方式负载到同种焦炭中对焦炭溶损反应作用的区别,并从催化作用、矿物质在焦炭中的分散方式和矿物质对焦炭显微结构作用三方面分析了导致作用不同的机理.同种矿物质无论以何种方式负载对炭的催化作用是相同的.吸附矿物质主要是均匀分散在焦炭表面,而添加矿物质则部分被炭基质包裹,两种方式提供的催化表面是不同的,添加到煤中的矿物质还可以通过对焦炭结构产生影响而导致对焦炭反应性的作用.     

超细改性矿物粉体增强硅橡胶

采用材料物理化学和复合材料的方法,系统地研究了８种矿物及其超细粉体和改性粉体与硅本的相互作用。结果表明,湍石、石英和硅灰石对硅橡胶基体具有较好的增强作用。粒径小、比面积大、长径比大等粉体性质好的填料,其增强性能高。界面粘附功与界面张力比值大的复合材料的力学性能好。具有表面活性基团（通过表面改性）、表面缺陷和一的表面羟基是提高粉体增强性能的重要因素。复合粉体的增强性能与粉休性质、混炼胶中的结合橡胶、     

Aluminosilicate coatings with enhanced heat- and corrosion resistance

This paper summarizes the results of development of heat- and acid resistant mineral coatings intended for protection of concrete structures and brickwork from exposure of acid media and elevated temperatures. The protective coatings are produced basing on the alkaline aluminosilicate bonds, in which the alkaline compounds are strongly bound into water insoluble hydroaluminosilicate complexes. On the contrary to the known-in-the-art mineral coatings based on cements containing slag and slag/ash, the coatings based on the alkaline aluminosilicates advantageously explore a correlation between corrosion resistance and phase composition due to the synthesis in the structure of the alkaline aluminosilicate matrix of high-silica zeolite-like phases (faujasite, chabazite and mordenite). The introduction into the alkaline aluminosilicate matrix of the formula Na₂O·Al₂O₃·6SiO₂·14.5H₂O of the acid resistant fillers, selected from mica, aluminosilicate microspheres and ground quartz sand taken in quantities of 3, 8 and 12 wt.% enabled to increase the acid resistance of the coatings by 1.25–1.5 fold compared to the known-in-the-art mineral analogs. Heat resistance of the coatings under study, in the conditions of alternate exposure of temperature (473 K) and vapors of oleum, may reach 100 cycles. The developed formulations of the anti-corrosion alkaline aluminosilicate coatings were successfully tried in 2007 in industrial conditions in repairing the deteriorated brickwork of the flue. After 5 years no sign of deterioration of the protective coating was reported.     

Influence of shear flow on the preparation of polymer layered silicate nanocomposites

In this paper the influence of melt-processing on the final polymer/layered silicate nanocomposite morphology is discussed. In particular the role of shear forces on the transformation of the original large clay agglomerates is of interest. Several polymer nanocomposites were prepared by melt-extrusion, involving polycaprolactone, poly(ethylene oxide), polyamide-12 or polyamide-6 as the matrix polymer. The nanocomposite morphology was characterised by X-ray diffraction and transmission electron microscopy and the clay tactoid morphology with polarised optical microscopy and scanning electron microscopy. The development of the tactoid and nanocomposite morphology during melt-mixing under shear was studied time-resolved by optical microscopy in conjunction with a rheometer and synchrotron X-ray scattering together with a Couette type flow cell. The shear forces in the melt-preparation of polymer layered mineral nanocomposites facilitate the break-up of large-sized agglomerates, whereas the extent of further exfoliation of the mineral layers is determined by the compatibility between the polymer matrix and the mineral layers rather than by shear forces.     

Normalized age applied to AAR occurring in concretes with or without mineral admixtures

This paper presents a method for assessing the normalized age factors, which allow accelerated alkali-aggregate reaction (AAR) tests performed at various temperatures (20, 40 and 60 °C) to be related to the conditions encountered in situ in concrete structures. The evaluation of normalized age factors is based on the comparison of many experimental results taken from the literature concerning laboratory tests and in situ measurements. The use of these factors permits us to evaluate, from the results of an accelerated test performed at 60 °C, the protection time against AAR that could be expected for in situ concretes containing mineral admixtures (silica fume and fly ashes). The results show that, in addition to the inhibitory action of mineral admixtures leading to a strong decrease in the final AAR-swelling, the protection against abnormal expansion caused by AAR increases significantly when mineral admixtures are used. Abnormal expansion is expected at 2-4 years for plain concrete compared to 7-50 years for concrete with mineral admixtures.     

A preliminary model of liberation from a binary system

In this first report, we present a preliminary model based on the simple binary system of component B occluded in a matrix of component A, for the case where fracture planes can pass with equal ease through A or B. By assuming that the volume fraction of B in AB in the overall matrix is small, which is realistic for many practical systems, the problem is reduced to a one-dimensional treatment which is conceptually easy to understand. The model was programmed for Monte Carlo simulation, and an analytical solution also developed based on the assumption using a synthetic ‘mineral—host matrix’ particle. Preliminary experimental confirmation using a synthetic ‘mineral—host matrix’ of known amount and size of B in AB is presented.     

Effect of organoclay chemistry and morphology on properties of poly(lactic acid) nanocomposites

Poly(lactic acid) (PLA) nanocomposites with different layered organoclays (variation in the surface treatment of silicate) and one special nanofiller (mixed mineral thixotrope) were melt-compounded using a semi-industrial co-rotating twin-screw extruder. Effects of the silicate surface treatment and shape on the structure as well on processing and utility properties in PLA matrix were investigated. The structural changes in polymer matrix were evaluated from dynamic experiments in the shear flow using low-amplitude oscillatory measurements. Moreover, new approach for morphological investigation of nanocomposites using small-angle X-ray scattering was presented. Concerning utility properties, tests of mechanical and barrier properties were performed to compare enhancement of PLA matrix due to incorporation of different nanoparticles. Surprisingly, filling the PLA matrix with mixed mineral thixotrope resulted into very high material performance (in particular, significant improvement in barrier properties) compared to filling with commercial layered silicates. In this way, new type of nanofiller for PLA applications has been successfully tested.     

巢湖三大优势资源的保护与开发

巢湖地区有着独特的区位优势,自然、人文和地质遗迹资源丰富。文章以矿产资源为切入点,以旅游资源为落脚点,从可持续发展的角度考虑,结合对巢湖地区矿产资源的开发与保护现状及其对环境地质(景观)的影响分析,认为这些不可再生的矿产资源并非巢湖的优势资源,巢湖风景名胜区、地质遗迹和人文资源才是巢湖真正的优势资源,并提出了对这三大优势资源的保护与开发建议。