Preparation and Performance of a Fluorine-Free and Alkali-Free Liquid Accelerator for Shotcrete

Based on aluminum sulfate,a fluorine-free and alkali-free liquid accelerator(FF-AF-A)was prepared in this study.The setting time and compressive strength of three cement types with different FF-AF-A dosages were fully investigated.The compatibility of the FF-AF-A with the superplasticizers were also investigated,and the early hydration behavior and morphology of the hydration products of reference cement paste with the FF-AF-A were explored by hydration heat,X-ray diffractometry(XRD),and scanning electron microscopy(SEM).Test results indicated that adding the FF-AF-A at 8 wt%of the cement weight resulted in 2 min 35 s initial setting time and 6 min 30 s final setting time.The 1-day compressive strength of the cement mortar with 8 wt%of FF-AF-A reached 13.5 MPa,which represents an increase of 35%as compared to the strength of cement mortar without the FF-AF-A,and the 28-day compressive strength ratio was 119%.In addition,the FF-AF-A also showed good compatibility with different superplasticizer dosages.The results show that,when the FF-AF-A was added to the cement paste,it promoted the formation of ettringite crystals due to the aluminum ions(Al^(3+))and sulfate ions(SO_(4)^(2-))reacted with gypsum in the cement,as well as promoted the hydration of tricalcium aluminate(C_(3)A)and tricalcium silicate(C3S)leading to the overall structure becomes more compact.As a consequence,the hydration heat rate of the cement sharply increased,the cement paste setting time is shortened,and the compressive strength of cement mortar is improved.

Design and Fabrication of a Bio-inspired Acceleration Sensor Using Liquid Mass Blocks

A linear acceleration sensor,which is inspired by the human balance organ,is designed and prepared. It uses a liquid mass-block and a symmetrical-electrodes metal-core polyvinylidene fluoride fiber(SMPF)as the sensor element. The output signal of the sensor has an exponential relationship with the excitation amplitude of the impacting vibration. It is capable of detecting the amplitude and the correct frequency for sinusoidal excitations using an exponential correlation. The experiments indicate that both the output signal of the sensor and the resonance frequency increase substantially with increasing diameter of the metal core. The first-order resonance frequencies of the sensors with 40,60,and 80 μm diameter metal wires are below 10 Hz,which is near the range of human body motion frequencies.

Separation-and-Recovery Technology for Organic Waste Liquid with a High Concentration of Inorganic Particles

The environmentally friendly and resourceful utilization of organic waste liquid is one of the frontiers of environmental engineering. With the increasing demand for chemicals, the problem of organic waste liq- uid with a high concentration of inorganic pollutants in the processing of petroleum, coal, and natural gas is becoming more serious. In this study, the high-speed self-rotation and flipping of particles in a three- dimensional cyclonic turbulent field was examined using a synchronous high-speed camera technique; the self-rotation speed was found to reach 2000-6000 rad.s 1. Based on these findings, a cyclonic gas- stripping method for the removal of organic matter from the pores of particles was invented. A techno- logical process was developed to recover organic matter from waste liquid by cyclonic gas stripping and classifying inorganic particles by means of airflow acceleration classification. A demonstration device was built in Sinopec＇s first ebullated-bed hydro-treatment unit for residual oil. Compared with the T-STAR fixed-bed gas-stripping technology designed in the United States, the maximum liquid-removal effi- ciency of the catalyst particles in this new process is 44.9% greater at the same temperature, and the time required to realize 95% liquid-removal efficiency is decreased from 1956.5 to 8.4 s. In addition, we achieved the classification and reuse of the catalyst particles contained in waste liquid according to their activity. A proposal to use this new technology was put forward regarding the control of organic waste liquid and the classification recovery of inorganic particles in an ebullated-bed hydro-treatment process for residual oil with a processing capacity of 2×106 t.a^1. It is estimated that the use of this new tech- nology will lead to the recovery of 3100 t.a 1 of diesel fuel and 647 t.a^1 of high-activity catalyst; in addi- tion, it will reduce the consumption of fresh catalyst by 518 t.a^1. The direct economic benefits of this process will be as high as 37.28 million CNY per year.

Comparison of properties of traditional and accelerated carbonated solidified/stabilized contaminated soils

The investigation of the long-term performance of solidified/stabilized （S/S） contaminated soils was carried out in a trial site in southeast UK. The soils were exposed to the maximum natural weathering for four years and sampled at various depths in a controlled manner. The chemical properties （e.g., degree of carbonation （DOC）, pH, electrical conductivity （EC）） and physical properties （e.g., moisture content （MC）, liquid limit CLL）, plastic limit （PL）, plasticity index （PI）） of the samples untreated and treated with the traditional and accelerated carbonated S/S processes were analyzed. Their variations on the depths of the soils were also studied. The result showed that the broad geotechnical properties of the soils, manifested in their PIs, were related to the concentration of the water soluble ions and in particular the free calcium ions. The samples treated with the accelerated carbonation technology （ACT）, and the untreated samples contained limited number of free calcium ions in solutions and consequently interacted with waters in a similar way. Compared with the traditional cement-based S/S technology, e.g., treatment with ordinary portland cement （OPC） or EnvirOceM, ACT caused the increase of the PI of the treated soil and made it more stable during long-term weathering. The PI values for the four soils ascended according to the order： the EnvirOceM soil, the OPC soil, the ACT soil, and the untreated soil while their pH and EC values descended according to the same order.

喷射混凝土用无碱液体速凝剂的现状与发展趋势

喷射混凝土常用于隧道、矿山井巷、城市地下空间等施工场景,已成为复杂工程施工必不可少的一种混凝土。速凝剂作为喷射混凝土必不可少的外加剂,经历了高碱粉体和低碱粉体的速凝剂时代,目前,无氯低碱液体速凝剂已得到大规模应用。然而,实际工程对速凝剂产品仍在不断提出更高的要求,液体速凝剂正朝着无氟无氯无碱的方向前进,从而继续推出更好的产品。本文回顾速凝剂的历史进程和发展,着重讨论速凝剂的作用机理,硫酸铝型无碱液体速凝剂主要组分的演变及由此带来的产品研制难题和对水泥基材料性能的影响,并论述课题组在无碱液体速凝剂与水泥的适应性研究方面取得的成果。

硫酸铝对高掺量流化床粉煤灰基泡沫混凝土性能的影响

随着新型循环流化床燃煤技术的发展,循环流化床粉煤灰(CFBFA)的排放量日益增加。结合我国北方地区冬季严寒时保温隔热材料需求量大的现状,采用高掺量CFBFA制备具有保温隔热性能的泡沫混凝土。针对泡沫混凝土存在的凝结时间长以及早期强度低等问题,本工作掺入硫酸铝进行改性,研究并分析了硫酸铝掺量对泡沫混凝土密度、强度和导热系数的影响。利用X射线衍射(XRD)、热重分析(TG)以及扫描电子显微镜(SEM)等研究了硫酸铝作用下CFBFA基泡沫混凝土的水化产物和微观形貌。此外,还利用3D轮廓仪分析了泡沫混凝土的孔隙结构。结果表明,硫酸铝促进了本体系早期AFt的生成,与基准组(硫酸铝掺量为0%(质量分数,下同))相比,15%硫酸铝掺量的CFBFA基泡沫混凝土的初凝时间缩短了470 min,10%硫酸铝掺量的泡沫混凝土3 d强度可达到10.43 MPa,导热系数为0.31 W·m^(-1)·K^(-1)。这种泡沫混凝土具有较快批量化生产的潜力。

无氟无氯无碱液体速凝剂的作用机理

速凝剂作为一种重要的混凝土外加剂,广泛应用于隧道、矿山井巷、堵漏抢修等工程中。综述了无氟无氯无碱液体速凝剂的由来,并重点揭示了硫酸铝型无氟无氯无碱液体速凝剂中硫酸铝对水泥水化的促进作用与机理,以及其它组分(包括酸、多醇类物质、醇胺类物质和硫酸镁等)对水泥水化的影响及机理。

Flow-Accelerated Corrosion in Pipe Wall Downstream of Orifice for Water and Air-Water Bubble Flows

An orifice is used widely as a flow meter or a contraction device in pipeline systems in hydro-power plants, thermal power plants, and chemical plants because of its simple construction, high reliability, and low cost. However, it is well known that flow-accelerated corrosion (FAC) occurs on the pipe wall downstream of the orifice. Some of the authors have examined FAC through experimental and numerical analyses and have reported that one of the major governing parameters of FAC for single-phase water flow is the pressure fluctuation p’ on the pipe wall, and also that pipe wall thinning rate TR can be estimated by p’. In addition, they have presented the effects of the ori-fice geometry on p’ or TR, and have described a method for suppressing p’ or TR. In the present study, FAC for a two-phase air-water bubble flow is examined and compared with the single-phase water flow experimentally. Further, it is shown that because p’ is also considered a governing parameter of FAC for a two-phase air-water bubble flow, TR can be estimated using p’. It is also indicated that, by using a downstream pipe with a smaller diameter than that of the upstream pipe, p’ or TR can be suppressed.

硫酸铝型无氟无碱液体速凝剂的制备

以硫酸铝和二乙醇胺为主要原料,将乙二醇、三乙醇胺作为辅料进行性能调节,通过优化各组分的用量,制备了一种新型无氟无碱液体速凝剂。使用基准水泥,对速凝剂的凝结时间和1d抗压强度进行了测定。结果显示,速凝剂掺量为7%时,4’12’’时达到初凝,9’23’’时达到终凝;1d的抗折强度和抗压强度分别为3.22MPa和12.39MPa。同时,该液体速凝剂对几种工程水泥也表现出了良好的适应性。

核酸提取装置的移液精度优化设计研究

为了提高核酸提取装置的移液精度和稳定性,以基于空气置换原理、活塞驱动方式的移液模块作为研究对象,提出了一种基于正弦函数的S型加减速曲线算法,并将其与匀加减速、抛物线型加减速曲线算法进行了仿真对比和实验验证。结果表明:采用基于正弦函数的S型加减速曲线算法的核酸提取装置,在移液量为10μL、20μL、50μL、100μL和200μL的不同工作条件下,移液精度均取得了显著的提升,同时实验数据的CV值满足JJG 646-2006移液器检定规程。

氟硅渣改性硫酸铝基无碱液体速凝剂对水泥性能的影响

本文采用氟硅渣对硫酸铝基无碱液体速凝剂进行了改性,并测试了氟硅渣改性后无碱液体速凝剂的性能指标。采用XRD、TG-DTG和SEM表征手段分析了氟硅渣改性硫酸铝基无碱液体速凝剂对水泥水化过程的作用机理。结果表明:随着氟硅渣用量的增加,砂浆的快凝效果和强度均呈先增大后减小的趋势;用氟硅渣改性无碱液体速凝剂时,氟硅渣的掺量以5.0%(质量分数)为宜,此时掺改性速凝剂水泥试件的初凝时间为1 min 20 s,终凝时间为5 min 20 s,1 d抗压强度为13.8 MPa,28 d抗压强度为52.4 MPa。氟硅渣中的二氧化硅与水泥水化产物氢氧化钙反应形成水化硅酸钙,有利于提高水泥的早期强度,但氟与氢氧化钙反应会产生大量的氟化钙沉淀,阻碍水泥水化硬化过程。

Development of an ultrathin liquid sheet target for laser ion acceleration at high repetition rates in the kilohertz range

A colliding microjet liquid sheet target system was developed and tested for pairs of round nozzles of 10,11 and 18μm in diameter.The sheet's position stability was found to be better than a few micrometers.Upon interaction with 50 mJ laser pulses,the 18μm jet has a resonance amplitude of 16μm at a repetition rate of 33 Hz,while towards 100 Hz it converges to 10μm for all nozzles.A white-light interferometric system was developed to measure the liquid sheet thickness in the target chamber both in air and in vacuum,with a measurement range of 182 nm±1μm and an accuracy of±3%.The overall shape and 3D shape of the sheet follow the Hasson±Peck model in air.In vacuum versus air,the sheet gradually loses 10%of its thickness,so the thinnest sheet achieved was below 200 nm at a vacuum level of 10±4mbar,and remained stable for several hours of operation.

药用弹性体密封件中3种秋兰姆类硫化促进剂的定量分析与风险评估

提出了超高效液相色谱-串联质谱法同时测定药用弹性体密封件中二硫化四甲基秋兰姆(TMTD)、二硫化四乙基秋兰姆(TETD)和二硫化四丁基秋兰姆(TBTD)含量的方法,并对其是否会与亚硝酸盐反应生成N-亚硝胺类致癌物进行了风险评估。称取1.00 g剪碎后的药用弹性体密封件样品,加入甲醇10 mL,超声提取40 min,提取液和甲醇洗涤液合并后经0.45μm微孔滤膜过滤,采用超高效液相色谱-三重四极杆质谱仪测定滤液中TMTD、TETD和TBTD的含量。以Eclipsepluse C_(18)色谱柱为固定相,以0.1%(体积分数)甲酸溶液-甲醇体系为流动相进行梯度洗脱;采用电喷雾离子源正离子模式和多反应监测模式进行质谱分析,外标法定量。结果表明:3种秋兰姆类硫化促进剂的质量浓度在一定范围内与峰面积呈线性关系,检出限(3S/N)为0.02~0.03 mg·kg^(-1);按照标准加入法对阴性样品进行加标回收试验,回收率为80.9%~103%,测定值的相对标准偏差(n=6)为2.4%~6.3%;方法用于6批实际样品分析,其中3批样品检出TETD,检出量为1.86~2.55 mg·kg^(-1),TMTD和TBTD均未检出;在酸性条件下,将上述3批阳性样品提取液与亚硝酸钠溶液进行反应,结果均检出N-亚硝基二乙胺,检出量为0.0190~0.0201 mg·kg^(-1),不符合法规要求,说明药用弹性体密封件产生N-亚硝胺类化合物的风险较高。

水溶剂加速萃取-超高效液相色谱串联质谱测定土壤中全氟羧酸

采用水溶剂加速萃取超高效液相色谱串联质谱法(UPLC-MS/MS)建立了土壤中6种全氟羧酸(PFCs)的分析方法,并对色谱分析条件、水溶剂萃取条件、固相萃取柱净化条件及实验材料选择等进行了优化。结果表明,以ACQUITY UPLC BEH C18色谱柱为分离柱,2.0 mmol/L乙酸铵水溶液为流动相A,甲醇为流动相B,梯度洗脱下可在9 min内完成6种PFCs的测试,检出限为0.03~0.4μg/kg。对实际土壤样品进行测定,加标回收率为90.7%~118%,相对标准偏差为5.6%~18.0%,精密度和准确度均较好。该方法前处理过程简单、易操作,仪器检测效率高、结果准确,能够满足土壤中PFCs的检测要求。

硫酸铝型无碱液体速凝剂组分及制备工艺研究现状

传统的碱性速凝剂虽然能在一定程度上满足工程需求,但其高粉尘排放和强腐蚀性等问题,限制了其应用的深度和广度,因此具备低碱性、优异的后期强度保留率等优势的无碱液体速凝剂,得到了国内外学术界和工程界的广泛关注。在无碱液体速凝剂的研究中,硫酸铝作为核心组分,凭借其丰富的铝离子和弱酸性特性,有效促进了水泥的水化,从而显著提升了速凝剂的性能。本文围绕硫酸铝型无碱液体速凝剂的组分研究及制备工艺展开论述,并对其未来发展趋势提出了展望,以期为硫酸铝型无碱液体速凝剂的技术进步和工程应用提供参考和建议。

旋转液体测量重力加速度的研究

利用FD-RLE-A型旋转液体综合实验仪,将之前的测量方法进行优化,减少了所测变量的个数,在相同的测量条件下使测量结果更加精确.给出一种简单快捷的调节激光束平行于转轴入射的方法.对用测旋转液体最低液面高度法和激光束平行转轴入射测斜率法测量重力加速度时如何选择旋转周期进行了研究.

硫酸铝型无碱速凝剂的合成及性能评价

喷射混凝土的凝结时间调节与早期强度发展和速凝剂的效能密不可分。本文通过甲酸、十八水硫酸铝、二乙醇胺、六水硝酸镁合成一种新型无碱液体速凝剂ALA,并对其促凝效能与作用机制进行研究。结果表明,ALA具有显著的促凝作用,随着ALA加量的增加,水泥砂浆的初终凝时间分别提前至4.6min和8.2min;ALA具有良好的温度适应性和外加剂相容性,与萘系/聚羧酸系减水剂协同作用时仍能发挥较好的促凝作用;ALA体系中引入的少量Mg^(2+),可与水泥水化产生的OH-结合并生成Mg(OH)_(2),这对固化水泥砂浆的体积收缩有一定的抑制作用;ALA中的Al^(3+)和SO_(4)^(2-)可在水化反应早期诱导大量钙矾石结晶沉积,以形成空间网络结构,促使水泥浆快速凝结。

加速溶剂萃取-固相萃取-超高效液相色谱-串联质谱法测定土壤中20种抗生素的含量

提出了加速溶剂萃取-固相萃取-超高效液相色谱-串联质谱法测定土壤中(氯霉素类、喹诺酮类、磺胺类和四环素类)20种抗生素含量的方法。土壤样品经除杂、脱水、冻干、研磨和过筛后,分取2.0 g,加入4 g硅藻土和20μL 1.00 mg·L^(−1)混合内标溶液。混合物经体积比1∶1的乙腈和乙二胺四乙酸二钠(Na2EDTA)-Mcllvaine缓冲液(pH 4)的混合液加速溶剂萃取后,收集萃取液,将其酸度调至pH 3.0,过HLB固相萃取柱。用10 mL水淋洗,10 mL体积比1∶1的甲醇和乙腈混合溶液洗脱柱子。收集洗脱液,将洗脱液氮吹至近干,用10%(体积分数)甲醇溶液定容至1.0 mL,过0.22μm滤膜,滤液供超高效液相色谱-串联质谱仪分析。在色谱分析中,以Kinetex C18色谱柱为固定相,以不同体积比的0.1%(体积分数)甲酸溶液和甲醇的混合溶液为流动相进行梯度洗脱。在质谱分析中,以电喷雾离子(ESI)源电离,多反应监测(MRM)模式检测,内标法定量。结果表明:20种抗生素在质量浓度0.50~250μg·L^(−1)内与其内标质量浓度的比值和峰面积比值呈线性关系,检出限(3.143s)为0.10~0.55μg·kg−1;2.0,10.0,100μg·kg^(−1)加标浓度水平下20种抗生素的回收率为60.0%~126%,测定值的相对标准偏差(n=6)为4.0%~19%。方法用于8个实际土壤样品的分析,检出了10种抗生素,检出量为2.2~75.6μg·kg−1。

高效液相色谱质谱法同时测定土壤中6种三唑类杀菌剂残留

建立加速溶剂萃取-高效液相色谱质谱法检测土壤中三唑醇、腈菌唑、三唑酮、戊唑醇、腈苯唑和氟菌唑残留的方法。6种三唑类杀菌剂在3.00~200μg·L^(-1)质量浓度范围内线性关系良好,样品加标回收率为87.5%~103.5%,6次测试结果相对标准偏差均小于5%。本方法操作简便快捷,测试结果准确可靠,检出限低,适用于土壤中痕量三唑类杀菌剂残留的检测。