A hydrated amorphous iron oxide nanoparticle as active water oxidation catalyst

Developing efficient water oxidation catalysts(WOCs)with earth‐abundant elements still remains a challenging task for artificial photosynthesis.Iron‐based WOC is a promising candidate because it is economically cheap,little toxic and environmentally friendly.In this study,we found that the catalytic water oxidation activity on amorphous iron‐based oxide/hydroxide(FeOx)can be decreased by an order of magnitude after the dehydration process at room temperature.Thermogravimetric analysis,XRD and Raman results indicated that the dehydration process of FeOx at room temperature causes the almost completely loss of water molecule with no bulk structural changes.Based on this finding,we prepared hydrated ultrasmall(ca.2.2 nm)FeOx nanoparticles of amorphous feature,which turns out to be extremely active as WOC with turnover frequency(TOF)up to 9.3 s^-1 in the photocatalytic Ru(bpy)3^2+‐Na2S2O8 system.Our findings suggest that future design of active iron‐based oxides as WOCs requires the consideration of their hydration status.

负载纳米TiO_(2)石英砂功能集料-水泥石的界面粘结性能

光催化水泥基材料是先进建筑功能材料的研究热点之一,但传统内掺法制备的TiO_(2)-水泥基复合材料中TiO_(2)有效利用率低、经济效益差。针对此问题,采用负载法制备纳米TiO_(2)功能集料(QST),并将QST集料负载于普通水泥砂浆表面。研究QST集料对水泥砂浆干缩性能的影响,通过拉拔法测试QST集料与水泥石的界面粘结力;采用SEM、EDS、MIP等微观测试方法,研究纳米TiO_(2)对集料-水泥石界面过渡区水化产物、孔结构的影响。结果表明:与普通石英砂集料相比,表面负载纳米TiO_(2)的石英砂功能集料可减少水泥砂浆的干缩,提高集料-水泥石的界面粘结力。在QST集料-水泥石的界面过渡区,纳米TiO_(2)促进了水泥浆体的水化,减少了界面过渡区Ca(OH)2的富集,细化并改善了界面过渡区的孔结构。

不同化学改性方法提高玉米芯骨料混凝土的性能

玉米芯具有较低的导热系数,可以作为天然的保温材料,用于混凝土砌块中。然而,由于玉米芯的多孔结构,导致玉米芯骨料混凝土的抗压强度偏低,亟需进行改性。为了推广玉米芯的规模化利用,该研究以玉米芯为原料改善混凝土砌块的性能,通过红外光谱、拉曼光谱和扫描电镜等测试手段,探讨了3种不同改性技术对玉米芯骨料混凝土水化产物化学键、分子结构、界面过渡区微观结构、抗压强度和导热系数的影响。结果表明:与环氧树脂改性相比,陶粒法改性和裹浆法改性不仅增加了玉米芯骨料混凝土界面过渡区的水化硅酸钙凝胶含量,同时也降低了界面过渡区的厚度,优化了混凝土砌块的微观结构、提高了混凝土砌块的抗压强度、降低了混凝土砌块的导热系数。其中,陶粒法改性技术的效果尤为明显。界面过渡区厚度水化硅酸钙特征峰由大到小顺序分别为陶粒法改性、裹浆法改性、环氧树脂改性。经过陶粒法改性、裹浆法改性和环氧树脂改性后,玉米芯骨料混凝土的界面过渡区分别为无明显界面过渡区、55~66 μm和93~101 μm之间。和未改性玉米芯骨料混凝土相比,掺30%陶粒法改性玉米芯骨料混凝土的抗压强度的导热系数分别降低了51.5%和32.2%。当掺入不超过15%的改性玉米芯骨料时,混凝土砌块满足国家标准GB/T8239-2014中对抗压强度的要求。为了改善玉米芯骨料混凝土砌块的综合性能,建议掺入不超过15%的陶粒法改性玉米芯骨料。研究结果为玉米芯在混凝土砌块中的大规模利用提供了依据,同时也为进一步改善混凝土砌块的相关性能提供了参考。

静态爆破剂水化速率对矿体力学及损伤作用机制研究

为了研究静态爆破剂水化速率对矿体力学及损伤作用机制,利用应力-损伤耦合模型进行了不同水化速率下矿体力学损伤数值模拟,分析了水化速率对矿体应力场及损伤区演化规律影响,揭示了钻孔布置模型对水化速率作用的机制。研究结果表明:静态爆破损伤区发育可以分为压实阶段、微损伤形成阶段、损伤区发育阶段、损伤区贯通阶段等4个阶段,其中损伤区发育、贯通阶段应力作用最为显著;矿体应力场及损伤区随着水化速率的增大而增加,并且在快速释能初期水化速率对应力场及损伤区影响差异性较小,快速释能后期水化速率对应力场及损伤区影响差异性显著;钻孔布置模型影响水化速率作用机制,其中单孔力学模型下水化速率促进膨胀压差异性,双孔力学模型下水化速率促进应力叠加,导向孔布置模型最为显著,初期水化速率加快应力运移,后期水化速率促进应力叠加,在时间维度和应力维度的共同作用下造成损伤区扩展、贯通;本次数值模拟和现场测试方案中,静态爆破剂水化速率1.8 MPa/min,钻孔直径113 mm,钻孔间距1000 mm,合理的孔间距与钻孔直径比η=9,导向孔布置模型可有效地致裂矿体、产生大量损伤区。该研究为提高静态爆破技术的致裂效果及施工布置提供了参考依据。

Characteristics of Gas Hydrate Stability Zone and Resource Evaluation in Okinawa Trough

According to the processing and interpretation of multichannel seismic reflection data in the area of Okinawa Trough, the BSR （bottom simulating reflector） was identified in 16 seismic profiles. By means of special processing technologies such as AVO and waveform inversion, the authors, for the first time, directly used the BSR to outline the distribution tendency of thickness of gas hydrate stability zone in the Trough and thought that the largest stability zone thickness was in the south and the smallest in the north. Then through calculation the authors got the thickness of hydrate stability zone and resource of the hydrate. This would be useful to the future hydrate exploration and resource evaluation in the Okinawa Trough.

产气微生物掺量对水泥基材料界面过渡区性能的影响

界面过渡区是混凝土结构中的薄弱部分,对混凝土的性能有重要影响。选用酵母菌作为产气微生物,研究了产气微生物掺量对水泥-骨料界面过渡区性能的影响。结果表明:酵母菌的加入加速了Ca(OH)_(2)的消耗,促进了CaCO_(3)、C-S-H等水化产物的生成,细化了界面过渡区结构,优化了界面过渡区产物组成,降低了界面过渡区宽度,并增加了显微硬度;当微生物掺量为80%时,界面过渡区的优化效果最佳,与无微生物时相比,界面过渡区的宽度减少了14.3%~15.4%,显微硬度增加了15.2%~25.1%。

多固废混凝土抗压性能及微观结构研究

为解决铁尾矿粉堆积问题,促进铁尾矿粉的资源化再利用,采用铁尾矿粉、钢渣粉、磷渣粉作为掺合料替代水泥制备混凝土,研究不同水胶比、铁尾矿粉研磨时间、掺合料掺量及掺合料配合比对混凝土抗压强度的影响。结果表明:水胶比为0.46促进了三元掺合料的后期水化反应,机械研磨2.0 h有助于提高铁尾矿粉活性,钢渣粉与磷渣粉有耦合作用,钢渣粉水化生成Ca(OH)_(2)有助于磷渣粉水化,当铁尾矿粉、磷渣粉、钢渣粉掺量分别为6.0%、8.0%、16.0%时,混凝土28 d强度达到45.0 MPa。微观分析表明,掺合料掺量为30%时试件孔隙率优于掺量20%的试件,增加掺合料掺量能改善混凝土孔结构。

铁基非晶纳米晶磁芯激光切割温度场仿真研究

为了明晰FeSiBCuNb非晶纳米晶磁芯激光切割过程的温度分布,采用熔融凝固模型、多相流模型,以及热源半径沿深度衰减的旋转体热源,在Fluent软件中通过生死单元法实现了激光切割的温度场模拟,得到了熔融切缝形貌。研究了激光功率和切割速度等工艺参数对切缝宽度和热影响区厚度的影响。结果表明:在厚度方向上磁芯被完全切开时,切缝宽度、热影响区厚度呈现上下窄、中间宽的形貌。随激光功率增大或切割速度减小,切缝宽度整体增大,厚度方向上切缝宽度更加不均匀。

基于分子动力学模拟的α-SiO_(2)纳米颗粒油-水界面吸附行为研究

纳米颗粒相界面吸附与自组装被广泛应用于石油采收、泡沫浮选、药物输送及新型功能材料等研究领域。然而,由于溶剂化力、静电斥力等多种相互作用所导致的吸附势垒,纳米颗粒自发吸附至界面的过程受到阻碍。基于分子动力学方法研究了α-SiO_(2)纳米颗粒相界面吸附动力学特征,深入分析了水化层结构及离子浓度对颗粒吸附行为的影响。首先,通过修饰表面基团获取了不同亲疏水性α-SiO_(2)纳米颗粒的吸附特征:纳米颗粒自发扩散至亚界面后会经历弛豫吸附至界面、快速吸附以及在界面区域经历一段弛豫后达到动态平衡三个过程。随后,从径向分布函数、角度分布、氢键密度分布等对纳米颗粒水化层结构以及氢键结构和进行了量化和比较,通过水化层内水分子驻留自相关函数以及氢键寿命分析了水化层结构及氢键结构的动力学特性。结果表明:水化层结构依赖于所作用颗粒的表面特性,与亲水表面相比,水分子在疏水表面具有明显的择优取向和更强的流动性;表面-水间氢键相互作用和水化层内特殊氢键结构是影响颗粒吸附的重要原因;不同离子效应可以通过共同作用干扰氢键结构以促进纳米颗粒相界面吸附。本研究为理解纳米颗粒相界面吸附动力学特性以及吸附壁垒形成机制提供参考,对于纳米颗粒相界面可控吸附在石油采收、新型功能材料等应用领域具有指导意义。

A Preliminary Study of the Gas Hydrate Stability Zone in the South China Sea

Based on the analysis of sea-bottom temperature and geothermal gradient, andby means of the phase boundary curve of gas hydrate and the sea-bottom temperature versus waterdepth curve in the South China Sea, this paper studies the temperature and pressure conditions forgas hydrate to keep stable. In a marine environment, methane hydrate keeps stable at water depthsgreater than 550 min the South China Sea. Further, the thickness of the gas hydrate stability zonein the South China Sea was calculated by using the phase boundary curve and temperature-depthequations. The result shows that gas hydrate have a better perspective in the southeast of theDongsha Islands. the northeast of the Xisha Islands and the north of the Nansha Islands for thickerstability zones.

Heat flow pattern,base of methane hydrates stability zones and BSRs in Shenhu Area,northern South China Sea

Using the collected 433 heat flow values, we estimated the bases of methane hydrate stability zone （BHSZ）, in northern South China Sea （NSCS）. Through comparing BHSZs with the depths of bottom simulating reflectors （BSRs）, in Shenhu Area （SA）, we found that there are big differences between them. In the north of SA, where the water depth is shallow, many slumps developed and the sedimentation rate is high, it appears great negative difference （as large as -192%）. However, to the southeast of SA, where the water depth is deeper, sedimentation rate is relatively low and uplift basement topography exists, it changes to positive difference （as large as ＋45%）. The differences change so great, which haven＇t been observed in other places of the world. After considering the errors from the process of heat flow measurement, the BSR depth, the relationship of thermal conductivity with the sediments depth, and the fluid flow activities, we conclude that the difference should be not caused by these errors. Such big disagreement may be due to the misunderstanding of BSR. The deviant ＂BSRs＂ could represent the paleo-BSRs or just gas-bearing sediment layers, such as unconformities or the specific strata where have different permeability, which are not hydraterelated BSRs.

Migration and accumulation characteristics of natural gas hydrates in the uplifts and their slope zones in the Qiongdongnan Basin,China

Various factors controlling the accumulation of natural gas hydrates(NGHs)form various enrichment and accumulation modes through organic combination.This study mainly analyzes the geological and geophysical characteristics of the NGHs occurrence in the uplifts and their slope zones within the deep-water area in the Qiongdongnan(QDN)Basin(also referred to as the study area).Furthermore,it investigates the dominant governing factors and models of NGHs migration and accumulation in the study area.The results are as follows.(1)The uplifts and their slope zones in the study area lie in the dominant pressure-relief direction of fluids in central hydrocarbon-rich sags in the area,which provide sufficient gas sources for the NGHs accumulation and enrichment through pathways such as gas chimneys and faults.(2)The top and flanks of gas chimneys below the bottom simulating reflectors(BSRs)show high-amplitude seismic reflections and pronounced transverse charging of free gas,indicating the occurrence of a large amount of gas accumulation at the heights of the uplifts.(3)Chimneys,faults,and high-porosity and high-permeability strata,which connect the gas hydrate temperature-pressure stability zones(GHSZs)with thermogenic gas and biogenic gas,form the main hydrate migration system.(4)The reservoir system in the study area comprises sedimentary interlayers consisting of mass transport deposits(MTDs)and turbidites.In addition,the reservoir system has developed fissure-and pore-filling types of hydrates in the pathways.The above well-matched controlling factors of hydrate accumulation enable the uplifts and their slope zones in the study area to become the favorable targets of NGHs exploration.

New indications of gas hydrate in the northeastern China permafrost zone

1.Objectives The Mohe Basin in Heilongjiang,China has a NEE thrust nappe belt,which was assembled by the root zone,middle thrust zone and thrust front,north-south and north-east normal faults with three tectonic activities of the Middle Jurassic to. Eocene,the Miocene,and the Early to Middle Pleistocene. The middle thrust zone and thrust front has a large number of folds,thrust faults,fractures and glutenites,which are the major structures of gas hydrate accumulation in the Mohe Basin.

Geothermal investigation of the thickness of gas hydrate stability zone in the north continental margin of the South China Sea

The exploration of unconventional and/or new energy resources has become the focus of energy research worldwide,given the shortage of fossil fuels.As a potential energy resource,gas hydrate exists only in the environment of high pressure and low temperature,mainly distributing in the sediments of the seafloor in the continental margins and the permafrost zones in land.The accurate determination of the thickness of gas hydrate stability zone is essential yet challenging in the assessment of the exploitation potential.The majority of previous studies obtain this thickness by detecting the bottom simulating reflectors（BSRs） layer on the seismic profiles.The phase equilibrium between gas hydrate stable state with its temperature and pressure provides an opportunity to derive the thickness with the geothermal method.Based on the latest geothermal dataset,we calculated the thickness of the gas hydrate stability zone（GHSZ） in the north continental margin of the South China Sea.Our results indicate that the thicknesses of gas hydrate stability zone vary greatly in different areas of the northern margin of the South China Sea.The thickness mainly concentrates on 200–300 m and distributes in the southwestern and eastern areas with belt-like shape.We further confirmed a certain relationship between the GHSZ thickness and factors such as heat flow and water depth.The thickness of gas hydrate stability zone is found to be large where the heat flow is relatively low.The GHSZ thickness increases with the increase of the water depth,but it tends to stay steady when the water depth deeper than 3 000 m.The findings would improve the assessment of gas hydrate resource potential in the South China Sea.

Influence of Hydrothermal Synthesis Conditions on the Formation of Calcium Silicate Hydrates:from Amorphous to Crystalline Phases

Hydrothermal treatment has been widely applied in the synthesis of well crystalline calcium silicate hydrate（CSH）, such as tobermorite and xonotlite. However, both morphology and crystallinity of CSH are greatly affected by the conditions of hydrothermal treatment including siliceous materials, temperature increase rate and isothermal periods. In this study, the influence of hydrothermal conditions on the growth of nano-crystalline CSH was investigated based on XRD analysis. Results showed that siliceous materials with amorphous nature（i e, nano silica powder） are beneficial to synthesize pure amorphous CSH, while the use of more crystallized siliceous materials（i e, diatomite and quartz powder） leads to producing crystalline CSH. Results also indicate that the formation of tobermorite and xonotlite is greatly affected by the temperature rise rate during hydrothermal treatment.

Internal structure of Longmenshan fault zone at Hongkou outcrop,Sichuan,China,that caused the 2008 Wenchuan earthquake

This paper reports the internal structures of the Beichuan fault zone of Longmenshan fault system that caused the 2008 Wenchuan earthquake, at an outcrop in Hongkou, Sichuan province, China. Present work is a part of comprehensive project of Institute of Geology, China Earthquake Administration, trying to understand deformation processes in Longmenshan fault zones and eventually to reproduce Wenchuan earthquake by modeling based on measured mechanical and transport properties. Outcrop studies could be integrated with those performed on samples recovered from fault zone drilling, during the Wenchuan Earthquake Fault Scientific Drilling （WFSD） Project, to understand along-fault and depth variation of fault zone properties. The hanging wall side of the fault zone consists of weakly-foliated, clayey fault gouge of about 1 m in width and of several fault breccia zones of 30-40 m in total width. We could not find any pseudotachylite at this outcrop. Displacement during the Wenchuan earthquake is highly localized within the fault gouge layer along narrower slipping-zones of about 10 to 20 mm in width. This is an important constraint for analyzing thermal pressurization, an important dynamic weakening mechanism of faults. Overlapping patterns of striations on slickenside surface suggest that seismic slip at a given time occurred in even narrower zone of a few to several millimeters, so that localization of deformation must have occurred within a slipping zone during coseismic fault motion. Fault breccia zones are bounded by thin black gouge layers containing amorphous carbon. Fault gouge contains illite and chlorite minerals, but not smectite. Clayey fault gouge next to coseismic slipping zone also contains amorphous carbon and small amounts of graphite. The structural observations and mineralogical data obtained from outcrop exposures of the fault zone of the Wenchuan earthquake can be compared with those obtained from the WFSD-1 and WFSD-2 boreholes, which have been drilled very close to the Hongkou outcrop. The presence of carbon and graphite, observed next to the slipping-zone, may affect the mechanical properties of the fault and also provide useful information about coseismic chemical changes.

Sedimentary characteristics comparison and genesis analysis of the deepwater channel in the hydrate enrichment zones on the north slope of the South China Sea

Natural gas hydrate(NGH) is one of the important clean energy at present and even in the future. The study of its sedimentary environment and minerogenetic condition has long been a hot issue that has received much concern from geologists all over the world. China has successfully obtained the samples of NGH in Shenhu and Dongsha sea areas in 2007, 2013 and 2015, respectively. From this, the continental slope north of the South China Sea becomes an important test site for the study of NGH sedimentary genesis and minerogenetic condition. NGH has been found in Shenhu, Dongsha and Qiongdongnan areas within the continental slope north of South China Sea,at different depths of water, with different sedimentary characteristics, gas genesis, and minerogenetic conditions.Using a seismic sedimentology theory, combining seismic facies results of each facies, sedimentary facies and evolution of each area are documented in turn establishing a sedimentary model by considering palaeogeomorphology, sea level change and tectonic movement. The channel system and MTD(Mass Transport Deposition) system among these three areas were compared focusing on the developing position, appearance and controlling factors. Relative location among three areas is firstly defined that Dongsha area in a nearprovenance steep upper slope, Shenhu area in a normal gentle slope and Qiongdongnan area in an awayprovenance flat plain. Besides, their channel systems are classified into erosional, erosional-aggradational and aggradational channel, and MTD systems into headwall domain, translational domain and toe domain.

New delineation of two favorable zones for gas hydrate in southem Qinghai and northern Tibet,China

1.ObjectivesSouthern Qinghai-northem Tibet permafrost region is a place having the most widespread and most developed permafrost in China with good mineralization conditions and prospecting potentials for gas hydrate (Zhu YH et al.,2011). In 2011,China Geological Survey initiated a special national program entitled "Gas hydrate resource exploration and trial mining",which signaled a prelude to a comprehensive gas hydrate survey in southern Qinghai-northern Tibet permafrost region.So far,appreciable progress has been made in the geological,geophysical,geochemical and drilling survey across a number of key blocks.This paper is intended to examine the fundamental conditions for gas hydrate mineralization based on previous findings,delineate favorable zones for gas hydrate mineralization,and to make contributions to the onshore gas hydrate resource exploration in China.

Nanoindentation Characteristics of Cement Paste and Interfacial Transition Zone in Mortar with Rice Husk Ash

The nanostructure of cementitious materials has important effects on concrete properties. The effects of rice husk ash（RHA） on cement hydration product phases and interfacial transition zone（ITZ） in mortar were investigated from the nano-scale structure perspective. The experimental results indicate that, with the increase of RHA dosages of samples, the volume fraction of high-density calcium-silicate-hydrate（HD C-S-H） in porosity and hydration product phases increases. The volume fractions of HD C-S-H in C-S-H of samples show an increasing trend with the increase of RHA dosages. RHA decreases the thickness of ITZ and increases the matrix elastic moduli of samples, however, the RHA dosoges hardly affect the thickness and elastic moduli.

新疆大石峡水利枢纽混凝土碱-硅酸反应抑制研究

新疆大石峡水利枢纽混凝土选用的骨料存在碱活性,可能导致工程产生碱骨料破坏问题,本文研究了当地粉煤灰和矿粉对碱-硅酸反应(ASR)的影响,并采用XRD和SEM-EDS测试分析了水化产物和界面过渡区的形态。结果表明:粉煤灰掺量≥20%(质量分数)或矿粉掺量≥40%(质量分数)都能显著抑制碱-硅酸反应;在纯水泥样品界面过渡区可以观察到无定形相,在含有粉煤灰或矿粉的样品中未观察到无定形相,这意味着碱-硅酸反应发生在纯水泥样品中;添加粉煤灰或矿粉降低了界面过渡区物相的Ca/Si摩尔比,抑制了碱-硅酸反应。