Dry Mix Slag—High-Calcium Fly Ash Binder. Part Two: Durability

This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na2CO3): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.

Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions

The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells, which is a major obstacle for deep petroleum and geothermal energy development. Previous attempts to address this problem has been unsatisfactory because they can only reduce the strength decline rate. This study presents a new solution to this problem by incorporating fly ash to the traditional silica-cement systems. The influences of fly ash and silica on the strength retrogression behavior of oil well cement systems directly set and cured under the condition of 200°C and 50 MPa are investigated. Test results indicate that the slurries containing only silica or fly ash experience severe strength retrogression from 2 to 30 d curing, while the slurries containing both fly ash and silica experience strength enhancement from 2 to 90 d. The strength test results are corroborated by further evidences from permeability tests as well as microstructure analysis of set cement. Composition of set cement evaluated by quantitative X-ray diffraction analyses with partial or no known crystal structure(PONKCS) method and thermogravimetry analyses revealed that the conversion of amorphous C-(A)-S-H to crystalline phases is the primary cause of long-term strength retrogression.The addition of fly ash can reduce the initial amount of C-(A)-S-H in the set cement, and its combined use with silica can prevent the crystallization of C-(A)-S-H, which is believed to be the working mechanism of this new admixture in improving long-term strength stability of oil well cement systems.

Dry Mix Slag—High-Calcium Fly Ash Binder. Part One: Hydration and Mechanical Properties

High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na2CO3 into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.

Lowering ash slagging and fouling tendency of high-alkali coal by hydrothermal pretreatment

High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.

Influence of fly ash on early-age cracking behavior of high-flowing concrete

The effects of quality and content of fly ash on the early-age cracking behavior of high-flowing concrete(HFC)were investigated.The early-age cracking behavior of the HFC was analyzed by combining the tests of evaporation capacity and electrical resistivity of the HFC.In these tests,a modified flat-type specimen was adopted.The results show that the HFC will have a lower evaporation capacity when it is mixed with fine fly ash,while it will have a higher evaporation capacity when grade III fly ash is used as mineral admixture.And the electrical resistivity rate of HFC reduces with the increase of the content of fly ash.A nonlinear relationship exists between the cracking time of HFC and the minimum electrical resistivity.The early-age cracking behavior of HFC with fly ash can be enhanced by appropriately increasing the fine particle content and MgO,K2O,and SO3 contents of fly ash.The optimal content of fly ash,which makes a satisfied early-age cracking behavior of HFC,is obtained.And when the content of fly ash exceeds a critical value,the early-age cracking behavior of HFC will rapidly decrease.

Synthesis of Mullite from High-alumina Fly Ash:a Case from the Jungar Power Plant in Inner Mongolia, Northern China

In this paper, an experimental study was conducted in order to test the feasibility of sintering mullite directly from the high-alumina fly ash, without adding any extra material. The results show that the mullite contents in most sintered samples are over 70%. The samples sintered from the beneficiated fly ash have a higher content of mullite than those from the as-received fly ash under the same synthetic conditions. To obtain an equal amount of mullite, a higher sintering temperature is needed for the beneficiated fly ash than for the as-received fly ash. Considering the physical properties of sintered mullite, the favorable sintering temperature is 1400℃ for the as-received fly ash and 1500℃ for the beneficiated fly ash. A higher sintering temperature and a shorter holding time are profitable to sintering mullite. The orthogonal test confirmed that the dominant factor affecting mullite synthesis is sintering temperature, and that the most profitable matching conditions are 200 MPa-1500℃-3 h for the as-received fly ash and 200 MPa-1500 ℃-4 h for the beneficiated fly ash.

基于高效解离-选择性絮凝耦合作用的煤气化渣提炭实验研究

煤气化渣是由煤气化工艺产生的一种富含铝硅酸盐、灰组分及残炭的大宗工业固体废弃物,其规模化生产对生态环境造成了严重的影响。因此,将煤气化渣进行炭-灰分离是实现其减量化、无害化和资源化利用的关键。以煤气化渣为研究对象,采用高效解离-选择性絮凝耦合作用的工艺,为实现煤气化渣更为合理、高效的资源化利用,减少煤气化渣带来的土壤、空气、水体资源等污染问题,对煤气化渣进行提炭实验研究。首先分析了煤气化渣的理化性质,其次采用单因素变量法探究了磨矿时间、pH、絮凝剂种类、絮凝剂用量、高速剪切转速对煤气化渣提炭实验的影响,以实现残余炭产品的高度富集。结果表明:原煤气化渣灰分质量分数为67.19%,普通湿筛筛上物料灰分质量分数为54.3%,当煤气化渣磨矿时间为5 s, pH为7,絮凝剂聚氧化乙烯用量为0.4 kg/t,在转速为4 000 r/min高速剪切15 min的条件下提炭效果最佳,最终可获得产率为26.6%、湿筛筛上灰分质量分数为43.3%的残炭产品。对比普通湿筛法,基于高效解离-选择性絮凝实验方法在普通湿筛的基础上灰分质量分数降低了11%,降灰效果明显。

微波灰化-高效液相色谱-电感耦合等离子体质谱(ICP-MS)法测定茶叶中的铬酸铅

为了准确测定茶叶中铬酸铅的含量,为市场监管提供判断依据,茶叶样品经微波灰化仪在500℃的条件下灰化50 min后,用0.25 mol/L的NaOH和0.14 mol/L的Na_(2)CO_(3)混合碱性提取液在90~95℃下不间断搅拌提取10 min,提取液经色谱柱分离后,用电感耦合等离子体质谱(ICP-MS)法测定^(52)Cr,建立了微波灰化-高效液相色谱-电感耦合等离子体质谱仪测定茶叶中铬酸铅的方法。研究表明,方法在5.00~500μg/L线性良好,相关系数为0.9998,方法检出限低至2.5 mg/kg,三水平加标回收率为91.3%~95.3%,精密度在1.1%~2.0%。与电炉灼烧茶叶相比,微波灰化具有检出限低、精密度高、准确度良好等特性,能够满足茶叶中铬酸铅的测定。

Accelerated Carbonation Assessment of High-Volume Fly Ash Concrete

The issue of concrete carbonation has gained importance in recent years due to the increase use in supplementary cementing materials (SCMs) in concrete mixtures. While there is general agreement that concrete carbonation progresses at maximum at a relative humidity of about 60%, the rate may differ in the case of cements blended with SCMs, especially with high-volume fly ash replacements. In this study, the effect of high-volume fly ash concrete exposed to low ambient relative humidity (RH) conditions (57%) and accelerated carbonation (4% CO2) is investigated. Twenty-three concrete mixtures were produced varying in cementitious contents (310, 340, 370, and 400 kg/m3), water-to-cementitious materials ratio (0.45 and 0.50), and fly ash content (0%, 15%, 30%, and 50%) using a low and high-calcium fly ash. The specimens were allowed 1 and 7 days of moist curing and monitored for their carbonation rate and depth through phenolphthalein measurements up to 105 days of exposure. The accelerated carbonation test results indicated that increasing the addition of fly ash also led to increasing the depth of carbonation. Mixtures incorporating high-calcium fly ash were also observed to be more resistant against carbonation than low-calcium fly ash due to the higher calcium oxide (CaO) content. However, mixtures incorporating high-volume additions (50%) specimens were fully carbonated regardless of the type of fly ash used. It was evident that the increase in the duration of moist curing from 1 day to 7 days had a positive effect, reducing the carbonation depth for both plain and blended fly ash concrete mixes, however, this effect was minimal in high-volume fly ash mixtures. The results demonstrated that the water-to-cementitious ratio (W/CM) had a more dramatic impact on carbonation resistance than the curing age for mixtures incorporating 30% or less fly ash replacement, whereas those mixtures incorporating 50% showed minor differences regardless of curing age or W/CM. Based on the compressive strength results, carbonation depth appeared to decrease with increase in compressive strength, but this correlation was not significant.

Dual-doping for enhancing chemical stability of functional anionic units in sulfide for high-performance all-solid-state lithium batteries

The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herein,we proposed an Al and O dual-doped strategy for Li_(3)PS_(4)SE to regulate the chemical/electrochemical stability of anionic PS_(4)^(3-)tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface.The optimized Li_(3.08)A_(10.04)P_(0.96)S_(3.92)O_(0.08)SE presents the highestσLi+of 3.27 mS cm^(-1),which is~6.8 times higher than the pristine Li_(3)PS_(4)and excellently inhibits the structural hydrolysis for~25 min@25%humidity at RT.DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities,e.g.,POS33-units.Moreover,Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE cycled stably in Li//Li symmetric cell over 1000 h@0.1 mA cm^(-2)/0.1 mA h cm^(-2),could be revealed to Li-Al alloy and Li_(2)Oat SE/Li interface impeding the growth of Li-dendrites during cycling.Resultantly,LNO@LCO/Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)/Li-In cell delivered initial discharge capacities of 129.8 mA h g^(-1)and 83.74%capacity retention over 300 cycles@0.2 C at RT.Moreover,the Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE presented>90%capacity retention over 200 and 300 cycles when the cell was tested with LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)cathode material vs.5 and 10 mg cm^(-2)@RT.

预先脱泥-精选工艺的应用效果分析

为解决当前针对高灰分、高泥化煤泥在实际分选操作中很难保证精煤的产率和质量的问题,在对选煤厂当前浮选工艺现状及其所存在的问题进行详细分析的基础上,对预先脱泥-精选工艺中的粗选浮选机类型进行确定,并对单独精选的分选效果进行分析。通过工业性试验验证了预先脱泥—粗选—精选—脱水等环节组成的浮选工艺对高灰分、高泥化煤泥的浮选效果和产品质量,达到了预期的目标。

MiR-142-3p Regulates ILC1s by Targeting HMGB1 via the NF-κB Pathway in a Mouse Model of Early Pregnancy Loss

Objective Innate lymphoid cells(ILCs)are a class of newly discovered immunocytes.Group 1 ILCs(ILC1s)are identified in the decidua of humans and mice.High mobility group box 1(HMGB1)is predicted to be one of the target genes of miR-142-3p,which is closely related to pregnancy-related diseases.Furthermore,miR-142-3p and HMGB1 are involved in regulating the NF-κB signaling pathway.This study aimed to examine the regulatory effect of miR-142-3p on ILC1s and the underlying mechanism involving HMGB1 and the NF-κB signaling pathway.Methods Mouse models of normal pregnancy and abortion were constructed,and the alterations of ILC1s,miR-142-3p,ILC1 transcription factor(T-bet),and pro-inflammatory cytokines of ILC1s(TNF-α,IFN-γand IL-2)were detected in mice from different groups.The targeting regulation of HMGB1 by miR-142-3p in ILC1s,and the expression of HMGB1 in normal pregnant mice and abortive mice were investigated.In addition,the regulatory effects of miR-142-3p and HMGB1 on ILC1s were detected in vitro by CCK-8,Annexin-V/PI,ELISA,and RT-PCR,respectively.Furthermore,changes of the NF-κB signaling pathway in ILC1s were examined in the different groups.For the in vivo studies,miR-142-3p-Agomir was injected in the uterus of abortive mice to evaluate the abortion rate and alterations of ILC1s at the maternal-fetal interface,and further detect the expression of HMGB1,pro-inflammatory cytokines,and the NF-κB signaling pathway.Results The number of ILC1s was significantly increased,the level of HMGB1 was significantly upregulated,and that of miR-142-3p was considerably downregulated in the abortive mice as compared with the normal pregnant mice(all P<0.05).In addition,miR-142-3p was found to drastically inhibit the activation of the NF-κB signaling pathway(P<0.05).The number of ILC1s and the levels of pro-inflammatory cytokines were significantly downregulated and the activation of the NF-κB signaling pathway was inhibited in the miR-142-3p Agomir group(all P<0.05).Conclusion miR-142-3p can regulate ILC1s by targeting HMGB1 via the NF-κB signaling pathway,and attenuate the inflammation at the maternal-fetal interface in abortive mice.

酸溶-电感耦合等离子体质谱法测定煤系样品中稀土元素的方法研究

煤和含煤岩系在特定地质条件下可以富集稀土等金属元素。煤及矸石燃烧后产生的飞灰,其金属元素富集度更高,有望成为稀土等关键矿产的替代来源之一。针对煤系样品有机物含量高、基体组成复杂等问题,本文通过溶样方式、消解酸体系、浸提液、质谱干扰及扣除等条件实验研究,利用高压密闭酸溶法和半密闭酸溶法建立了分别适用于煤和煤系样品中稀土元素的电感耦合等离子体质谱(ICP-MS)分析方法。结果表明,硝酸-氢氟酸高压密闭酸溶法能够实现煤中稀土元素的准确测定,但对煤飞灰和煤矸石的稀土元素回收率不稳定,不同样品稀土回收率在37%~123%之间。在原有消解酸体系中,加入硫酸和高氯酸或改用盐酸复溶,均不能有效地提高稀土元素的回收率。五酸半密闭酸溶可以实现煤飞灰、煤矸石等煤系样品中稀土元素的完全分解。利用X射线衍射(XRD)和扫描电子显微镜(SEM)技术对煤系样品中元素的赋存状态进行了初步解析,揭示了高铝矿物是造成煤矸石等煤系样品中稀土元素溶出率低的主要原因,为实验方案的制定和优化提供了理论依据。利用标准物质和实际样品开展了方法验证,所建方法具有良好的精密度(相对标准偏差为0.05%~9.98%)和正确度(相对误差为-10.2%~7.62%),检出限低,可以实现煤系样品中稀土元素的多元素准确测定,适用于大批量样品中稀土元素的分析测试。

高温对碳纤维增强粉煤灰-偏高岭土基地聚合物砂浆性能影响研究

研究了碳纤维增强粉煤灰-偏高岭土(FA-MK)基地聚合物砂浆经200、400、600℃处理后的力学性能、外观和微观形貌等,探讨了碳纤维对地聚合物砂浆耐高温性能的改善机理。结果表明:碳纤维的掺入可改善地聚合物砂浆的耐高温性能。20~600℃时,试件的抗压强度随碳纤维体积掺量的增加呈先上升后下降趋势;温度高于400℃时,试件的抗折强度随碳纤维体积掺量的增加呈上升趋势。就高温后力学性能而言,碳纤维的最佳体积掺量为0.50%。温度对试件力学性能影响显著,随着温度的升高,试件颜色由深变浅,力学性能先上升后下降。较高温度时,试件强度损失随高温持时的增加而逐渐加剧。结果表明,在较高温度下地聚合物内部N-A-S-H/C-A-S-H凝胶受热分解、砂浆基体内部裂缝增多及碳纤维熔断是试件强度下降的重要原因。

前列腺癌患者外周血中CD4^+CD25^(high)调节性T细胞及调节因子TGF-β1和COX-2的表达

目的:通过检测前列腺癌患者以及健康志愿者外周血中CD4+CD25high调节性T细胞、TGF-β1及COX-2的表达,初步探讨CD4+CD25high调节性T细胞在前列腺癌发病机制中的作用及其与TGF-β1和COX-2的相关性。方法:应用流式细胞术检测30例前列腺癌患者治疗前后(其中前列腺癌局限组11例,非局限组19例)及20例健康志愿者外周血单个核细胞(PBMC)中CD4+CD25high调节性T细胞占CD4+T细胞的比例;应用酶联免疫吸附试验(ELISA)检测其外周血清中TGF-β1和COX-2的表达。对前列腺癌患者上述指标进行术前术后对比分析,另对CD4+CD25high调节性T细胞与TGF-β1及COX-2的相关性进行分析;并探讨上述指标在前列腺癌患者局限组和非局限组间是否存在差异性。结果:流式细胞术检测显示,前列腺癌患者治疗前PBMC中CD4+CD25high调节性T细胞占CD4+T细胞的比例为(18.32±7.49)%,高于健康志愿者对照组(7.77±1.86)%(P<0.05)。前列腺癌患者治疗后其比值为(17.34±5.87)%,较治疗前稍减低,但两者相比无显著差异(P>0.05)。ELISA检测外周血清中TGF-β1和COX-2显示,前列腺癌组分别为(215.97±55.16)ng/ml和(6.88±5.14)ng/ml,对照组分别为(149.75±47.11)ng/ml和(5.65±2.69)ng/ml;前列腺癌患者外周血清中TGF-β1的表达水平高于健康志愿者对照组(P<0.05),COX-2的表达水平与对照组无显著差异(P>0.05)。通过多重线性回归分析表明,前列腺癌患者PBMC中CD4+CD25high调节性T细胞的表达与血清中TGF-β1和COX-2的表达无显著相关。前列腺癌局限组和非局限组外周血中CD4+CD25high调节性T细胞、TGF-β1及COX-2的表达均无显著性差异(P>0.05)。结论:前列腺癌患者PBMC中CD4+CD25high调节性T细胞可能参与前列腺癌的发生,其增殖机制与血清中TGF-β1和COX-2的表达无关,可能与肿瘤本身及肿瘤局部微环境相关。

Impact Properties of Engineered Cementitious Composites with High Volume Fly Ash Using SHPB Test

The split Hopkinson pressure bar （SHPB） testing with diameter 40 mm was used to investigate the dynamic mechanical properties of engineered cementitious composites （ECCs） with different fly ash content. The basic properties including deformation, energy absorption capacity, strain-stress relationship and failure patterns were discussed. The ECCs showed strain-rate dependency and kept better plastic flow during impact process compared with reactive powder concrete （RPC） and concrete, but the critical compressive strength was lower than that of RPC and concrete. The bridging effect of PVA fiber and addition of fly ash can significantly improve the deformation and energy absorption capacities of ECCs. With the increase of fly ash content in ECCs, the static and dynamic compressive strength lowered and the dynamic increase factor enhanced. Therefore, to meet different engineering needs, the content of fly ash can be an important index to control the static and dynamic mechanical properties of ECCs.

Static and Dynamic Leaching Experiments of Heavy Metals from Fly Ash-Based Geopolymers

The feasibility of high calcium fly ash （CFA）-based geopolymers to fix heavy metals were studied. The CFA-based geopolymers were prepared from CFA, flue gas desulfurization gypsum （FGDG）, and water treatment residual （WTR）. The static leaching showed that heavy metals concentrations from CFA- based geopolymers were lower than their maximum concentration limits according to the U.S. environmental protection law. And the encapsulated and fixed ratios of heavy metals by the CFA-based geopolymers were 96.02%-99.88%. The dynamic real-time leaching experiment showed that concentration of Pb （II） was less than 1.μg / L, Cr （VI） less than 3.25 mg / L, while Hg （II） less than 4.0 μg / L. Additionally, dynamic accumulated leaching concentrations were increased at the beginning of leaching process then kept stable. During the dynamic leaching process, heavy metals migrated and accumulated in an area near to the solid-solution interface. When small part of heavy metals in ＂the accumulated area＂ breached through the threshold value of physical encapsulation and chemical fixation they migrated into solution. The dynamic leaching ratios and effective diffusion coefficients of heavy metals from CFA-based geopolymer were very low and the long-term security of heavy metals in CFA-based geopolymer was safe.