纤维素纳米晶对胶凝复合材料耐酸性能的影响

Acid mine drainage presents an important threat to cementitious structures. This study is aimed at investigating the effect of cellulose nanocrystals (CNCs) on the acid resistance of cementitious composites. CNCs were added to mortar mixtures as additives at cement volume ratios of 0.2vol%, 0.4vol%, 1.0vol%, and 1.5vol%. After 28 d of standard curing, the samples were immersed in a sulfuric acid with a pH value of 2 for 75 d. The unconfined compressive strength (UCS) test, the density, water absorption, void volume test, and thermogravimetric analysis were carried out to investigate the properties of CNC mixtures before sulfuric acid immersion. It was found that the addition of CNC reduced the volume of permeable voids and increased the hydration degree and mechanical strength of the samples. Changes in mass and length were monitored during immersion to evaluate the acid resistance of mixtures. The mixture with 0.4vol% CNC showed a reduced mass change and length change indicating its improved acid resistance.     

搅拌铸造法制备和表征GNPs和CNTs增强Al 7075基复合材料

This study investigated the effects of adding graphene nanoplates (GNPs) and carbon nanotubes (CNTs) into the Al7075 matrix via the stir casting method on the microstructure and mechanical properties of the fabricated composites. By increasing the volume fraction of reinforcements, the fraction of porosity increased. The X-ray diffraction results showed that the addition of reinforcements into the Al7075 changed the dominant crystal orientation from (002) to (111). Field emission scanning electron microscopy images also showed the distribution of clustered reinforcements in the matrix. Between the two reinforcements, the addition of CNTs generated a lower fraction of porosities. Through the addition of 0.52vol% GNPs into the matrix, the hardness, ultimate tensile strength and uniform elongation increased by 44%, 32%, and 180%, respectively. Meanwhile, the presence of 0.71vol% CNTs in the matrix increased the hardness, tensile strength and uniform elongation by 108%, 129%, and 260%, respectively.     

机械合金化法制备的Cu/SiC纳米复合材料的组织、热性能和力学性能评估

Nano-sized silicon carbide (SiC: 0wt%, 1wt%, 2wt%, 4wt%, and 8wt%) reinforced copper (Cu) matrix nanocomposites were manufactured, pressed, and sintered at 775 and 875°C in an argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy were performed to characterize the microstructural evolution. The density, thermal expansion, mechanical, and electrical properties were studied. XRD analyses showed that with increasing SiC content, the microstrain and dislocation density increased, while the crystal size decreased. The coefficient of thermal expansion (CTE) of the nanocomposites was less than that of the Cu matrix. The improvement in the CTE with increasing sintering temperature may be because of densification of the microstructure. Moreover, the mechanical properties of these nanocomposites showed noticeable enhancements with the addition of SiC and sintering temperatures, where the microhardness and apparent strengthening efficiency of nanocomposites containing 8wt% SiC and sintered at 875°C were 958.7 MPa and 1.07 vol%?1, respectively. The electrical conductivity of the sample slightly decreased with additional SiC and increased with sintering temperature. The prepared Cu/SiC nanocomposites possessed good electrical conductivity, high thermal stability, and excellent mechanical properties.     

硫酸中香蕉皮还原低品位锰矿的浸出行为及动力学模型

Manganese was leached from a low-grade manganese ore (LGMO) using banana peel as the reductant in a dilute sulfuric acid medium. The effects of banana peel amount, H₂SO₄ concentration, reaction temperature, and time on Mn leaching from the complex LGMO were studied. A leaching efficiency of ~98% was achieved at a leaching time of 2 h, banana peel amount of 4 g, leaching temperature of 120°C, manganese ore amount of 5 g, and sulfuric acid concentration of 15vol%. The phase, microstructural, and chemical analyses of LGMO samples before and after the leaching process confirmed the successful leaching of manganese. Furthermore, the leaching process followed the shrinking core model and the leaching rate was controlled by a surface chemical reaction (1 ? (1 ? x)1/3 = kt) mechanism with an apparent activation energy of 40.19 kJ·mol?1.     

木质素—栲胶高强度堵剂的制备

木质素磺酸盐—磺化栲胶混合物(简称LT)可用于配制高强度油井堵剂,堵剂配方为LT14％～20％,尿素5％～8％,36％甲醛溶液11％～17％,硼砂1.0％～2.5％,亚硫酸钠1.0％,硅酸钠0.5％,在pH值5～7、温度40～50℃条件下,固化时间为2～25h,堵剂固结后的抗压强度高达1.2MPa,且具有良好的耐酸、耐盐和耐水性。     

不同条件下铱负载催化剂性能的比较研究

To discuss the potential role of iridium (Ir) nanoparticles loaded under atmospheric and high pressures, we prepared a series of catalysts with the same active phase but different contents of 10wt%, 20wt%, and 30wt% on gamma-alumina for decomposition of hydrazine. Under atmospheric pressure, the performance of the catalyst was better when 30wt% of the Ir nanoparticles was used with chelating agent that had greater selectivity of approximately 27%. The increase in the reaction rate from 175 to 220 h?1 at higher Ir loading (30wt%) was due to a good dispersion of high-number active phases rather than an agglomeration surface. As a satisfactory result of this investigation at high pressure, Ir catalysts with different weight percentages showed the same stability against crushing and activity with a characteristic velocity of approximately 1300 m/s.     

化学发光-酶联免疫高灵敏检测洛美沙星

建立了洛美沙星的化学发光-酶联免疫分析方法。实验对包被抗原的度盘浓度、洛美沙星抗体及辣根过氧化物酶标记的羊抗兔二抗的稀释倍数、酶标板的种类等进行了优化。在最佳实验条件下,测得的IC₅₀值为0.22ng／mL, 检测限为0.032ng／mL。该方法具有良好的特异性,在检测的10种代表性的喹诺酮类药物中,仅诺氟沙星和氟罗沙星交叉率高于1％(分别为:6.88％和2.16％)。将该方法应用于脱脂牛奶中添加洛美沙星回收率的测定,批内和批间回收率分别为:88.7％～103.4％和97.8％～107.2％,相应变异系数分别为:6.3％～8.6％和2.4％～8.0％。     

施用稻壳炭对黄棕壤氮磷淋失及微生物生物量碳氮含量的影响

【目的】为减少农田氮磷淋失,提高土壤肥力,探究高孔隙度的稻壳炭在增强黄棕壤对养分元素吸附的特征。【方法】采用室内土柱淋溶试验,研究不同稻壳炭施用量(质量占比分别为0、1%、4%、8%、12%)条件下,黄棕壤总氮(TN)、硝态氮(NO^-₃-N)、铵态氮(NH⁺₄-N)、总磷(TP)、磷酸根(PO^3-₄)及可溶性有机碳(DOC)的淋失变化,并对黄棕壤氮磷养分和土壤微生物生物量的变化进行分析。【结果】随着施用量的增加,稻壳炭对黄棕壤TN、NO^-₃-N、NH⁺₄-N、DOC淋失的抑制效应增强,最佳施用量为12%时,TN、NO^-₃-N、NH⁺₄-N及DOC的淋失量与对照相比分别减少了85.41%、85.16%、92.61%、32.02%; 随其施用量的增加,稻壳炭对黄棕壤中P淋失的抑制效应不显著,TP和PO^3-₄的淋失量反而增加,TN、NO^-₃-N、有效磷(AP)及土壤微生物生物量碳氮(SMBC、SMBN)含量增高,而NH⁺₄-N含量减少。【结论】稻壳炭可以有效抑制黄棕壤氮素及DOC的淋失,对磷素的淋失抑制效果不显著。     

基于多尺度区域块的糖尿病性视网膜病变级联检测

目前,基于形态学检测糖尿病性视网膜病变的算法复杂度较高,深度学习直接逐像素检测的方法虽然能够避免排除生理结构、手动设计特征的不足,但计算量大、分割速度较慢.为了解决上述问题,提出一种基于深度学习的级联检测框架.首先,分块检测眼底图像是否存在病变区域,然后对病变区域进行逐像素的分割,从而检测出微动脉瘤、出血点、硬渗出及软渗出4种病变.实验结果表明:在眼底图像公开数据库DIARETDB1中,4种病变的检测率分别为88.62%、94.91%、98.91%和92.91%.与形态学方法相比,微动脉瘤和出血点检测精度分别提高了17.39%和15.18%;与直接逐像素检测方法相比,平均检测时间仅为原来的1/4.     

新型高威力含铝硝铵炸药的研究

该文以一种含有大量微气泡、自身敏化的膨化硝酸铵为氧化剂,以木粉、燃料油和铝粉为还原剂,制成新型高威力含铝硝铵炸药,通过建构含C、H、O、N、Al元素工业炸药炸药方设计最优化的数学模型,计算得到含铝硝铵炸药的较佳配方为硝酸铵85.5%-89.5%、木粉3.5%-4.5%、复合油相2.0%-3.0%、铝粉5.0%-7.0%,该炸药的爆炸性能为：装药密度0.91-95g/cm^3,爆速3600-3800m/s,列爆距离12-14cm,猛度16-17mm,作功能力370-390mL,文中还讨论了含铝硝铵炸药中铝粉含量与爆炸性能的关系,结果显示当铝粉含量为6.5%-7.0%,炸药作功能力达到最大值。     

水溶性海星皂苷的分离纯化及其抗真菌活性研究

为了分离纯化出具有强抗真菌活性的水溶性海星皂苷,以罗氏海盘车(Asterias rollestoni)腕为实验材料,利用水抽提方法获得水溶性海星皂苷粗品,依次利用大孔树脂和硅胶柱层析对水溶性海星皂苷进行了纯化,并对其抗真菌活性进行了测定。研究结果发现,在30％、50％、70％、80％、95％乙醇溶液的大孔树脂柱层析洗脱组分中,70％乙醇溶液洗脱组分对白色念珠菌和裂殖酵母菌的抗真菌活性最强。70％乙醇溶液洗脱组分经硅胶柱层析进一步纯化后,得到了SF-1、SF-2、SF-3和SF-4四种纯化样品,其中SF-1纯化样品没有抗真菌活性,SF-2纯化样品具有极弱的抗真菌活性,SF-3和SF-4纯化样品均具有很强的抗真菌活性。SF-3纯化样品在高压液相柱层析(HPLC)图谱中仅显示单一洗脱峰,表明其纯度很高,可应用于高效抗真菌药物的研制。研究结果为利用水溶性海星皂苷研制高效抗真菌药物奠定了基础。     

Tuning Li3PO4 modification on the electrochemical performance of nickel-rich LiNi0.6Co0.2Mn0.2O2

Surface deterioration occurs more easily in nickel-rich cathode materials with the increase of nickel content. To simultaneously pre-vent deterioration of active cathode materials and improve the electrochemical performance of the nickel-rich cathode material, the surface of nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material is decorated with the stable structure and conductive Li3PO4 by a facile method. The LiNi0.6Co0.2Mn0.2O2–1wt％, 2wt％, 3wt％Li 3PO4 samples deliver a high-capacity retention of more than 85％ after 100 cycles at 1 C under a high voltage of 4.5 V. The effect of different coating amounts (0–5wt％) for the LiNi0.6Co0.2Mn0.2O2 cathode is analyzed in detail. Results show that 2wt％ coating of Li3PO4 gives better performance compared to other coating concentrations. Detailed analysis of the structure of the samples during the charge?discharge process is performed by in-situ X-ray diffraction. It is indicated that the modification for LiNi0.6Co0.2Mn0.2O2 cathode could protect the well-layered structure under high voltages. In consequence, the electrochemical performance of modified samples is greatly improved.     

高效液相色谱法检测鸡蛋中的三聚氰胺

建立了高效液相色谱法检测鸡蛋中三聚氰胺的方法。样品用1%三氯乙酸和2.2%乙酸铅超声提取。色谱柱为HypersilODS100×4.6mm,5μm;流动相为乙腈:辛烷磺酸钠离子对试剂(pH=3)=15:85(V/V);流速为1mL/min;检测波长为210nm;柱温为40℃。三聚氰胺在0.2μg/mL～10μg/mL范围内,有良好的线性关系。在空白样品中添加0.2μg/mL、0.4μg/mL、1.0μg/mL三个质量浓度的标准工作液,回收率在82.0%～104.0%,相对标准偏差为6.81%(n=9)。     

基于低镁烧结矿和熔剂性球团的综合炉料熔滴性能研究

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace slag. This study investigated the effect of MgO content in sinter on the softening–melting behavior of the mixed burden based on fluxed pellets. When the MgO content increased from 1.31wt% to 1.55wt%, the melting temperature of sinter increased to 1521°C. Such an increase was due to the formation of the high-melting-point slag phase. The reduction degradation index of sinter with 1.31wt% MgO content was better than that of others. The initial softening temperature of the mixed burden increased from 1104 to 1126°C as MgO content in sinter increased from 1.31wt% to 1.55wt%, and the melting temperature decreased from 1494 to 1460°C. The permeability index (S-value) of mixed burden decreased to 594.46 kPa·°C under a high MgO content with 1.55wt%, indicating that the permeability was improved. The slag phase composition of burden was mainly akermarite (Ca₂MgSiO₇) when the MgO content in sinter was 1.55wt%. The melting point of akermarite is 1450°C, which is lower than other phases.     

Reverse-transformation austenite structure control with micro/nanometer size

To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. The samples were first cold-rolled, and then samples deformed to different extents were annealed at different temperatures. The microstructure evolutions were analyzed by optical microscopy, scanning electron microscopy (SEM), magnetic measurements, and X-ray diffraction (XRD); the mechanical properties are also determined by tensile tests. The results showed that the fraction of stain-induced martensite was approximately 72% in the 90% cold-rolled steel. The micro/nanometric microstructure was obtained after reversion annealing at 820-870℃ for 60 s. Nearly 100% reversed austenite was obtained in samples annealed at 850℃, where grains with a diameter ≤ 500 nm accounted for 30% and those with a diameter >0.5 μm accounted for 70%. The micro/nanometer-grain steel exhibited not only a high strength level (approximately 959 MPa) but also a desirable elongation of approximately 45%.     

Two-stage reduction for the preparation of ferronickel alloy from nickel laterite ore with low Co and high MgO contents

The preparation of ferronickel alloy from the nickel laterite ore with low Co and high MgO contents was studied by using a pre-reduction-smelting method. The effects of reduction time, calcination temperature, quantity of reductant and calcium oxide (CaO), and pellet diameter on the reduction ratio of Fe and on the pellet strength were investigated. The results show that, for a roasting temperature >800℃, a roasting time >30 min, 1.5wt% added anthracite coal, 5wt% added CaO, and a pellet size of~10 mm, the reduction ratio of Fe exceeds 70% and the compressive strength of the pellets exceeds 10 kg per pellet. Reduction smelting experiments were performed by varying the smelting time, temperature, quantity of reductant and CaO, and reduction ratio of Fe in the pellets. Optimal conditions for the reduction smelting process are as follows:smelting time, 30-45 min; smelting temperature, 1550℃; quantity of reductant, 4wt%-5wt%; and quantity of CaO, 5wt%; leading to an Fe reduction ratio of 75% in the pellets. In addition, the mineral composition of the raw ore and that during the reduction process were investigated by process mineralogy.     

BP神经网络IF钢铝耗的预测模型

为了解决某钢厂IF钢冶炼RH精炼过程铝耗偏高问题,通过数理统计和BP神经网络相结合的方法建立了铝耗预测模型,并与多元线性回归模型进行比较,该模型具有更高准确度.该模型分析了不同冶炼工艺参数对铝耗的具体影响,并对相应工艺参数进行了优化.结果表明:脱碳结束氧活度或RH进站氧活度降低0.005％左右,每吨钢铝耗可降低0.07～0.08kg,铝脱氧有效利用系数为70.31％～80.35％;RH进站钢液温度增加35～40℃,铝耗降低1kg左右,铝热反应升温利用系数在97.4％左右;吹氧量小于100m3和大于100m3时,氧气与铝反应的比例分别为37.3％和74.6％左右,吹氧量每增加50m3,铝耗分别增加0.1kg和0.2kg左右.工艺参数优化后平均铝耗由1.359kg降低到1.113kg,降幅达18.1％.     

水溶性海星皂苷的分离纯化及其抗肿瘤活性研究

为利用废弃海星壳资源开发出纯天然抗肿瘤药物,通过AB-8型吸附树脂、常压硅胶与Sephadex LH-20葡聚糖凝胶的柱层析技术,从罗氏海盘车(Asterias rollestoni Bell)壳的水抽提液中分离纯化出水溶性海星皂苷,并对其体内外抑瘤活性进行了研究。分离纯化与性质鉴定的结果显示,所得水溶性海星皂苷的性质隶属于甾体皂苷,其纯化样品的纯度可高达99.6％;体外抑瘤活性检测结果证实,所得皂苷纯品对HeLa宫颈癌细胞、SGC-7901胃癌细胞、A-549肺癌细胞和Bel 7402肝癌细胞均具有显著的抑制活性。50mg／L皂苷对这4种癌细胞的抑制率分别为(92.06±2.60)％、(95.22±2.87)％、(95.04±3.30)％和(91。60±4。30)％,其IC50值分别为7.05、5.28、5.32、6.16mg／L。体内抑瘤活性检测结果证实,灌胃剂量为2、 5、 10μg／g的皂苷纯品对S180实体瘤荷瘤小鼠均具有显著的抑制活性,并具有浓度依赖性,10μg／g皂苷纯品的抑瘤率可高达46.27％,高于10μg／g抗肿瘤药物环磷酰胺(CTX)的抑瘤率(41.04％);同时,2、 5、 10μg／g的皂苷纯品还均能浓度依赖性地显著提高荷瘤小鼠的胸腺指数和脾指数。     

红松成熟胚愈伤组织诱导外植体选择及培养条件优化

【目的】通过培养条件的优化和适宜外植体类型的筛选,解决红松成熟胚愈伤组织诱导中存在的愈伤组织诱导率低、生长状态差、褐化率较高等问题,为建立红松成熟胚体胚发生体系奠定基础。【方法】用5种培养基类型、3种蔗糖浓度和9种植物生长调节剂组合,选择8种来源于成熟种子不同部位的外植体,对愈伤组织诱导的培养条件和适宜外植体类型进行优化和筛选。【结果】① 在5种培养基中,DCR培养基上愈伤组织诱导率高于其他培养基、生长状态好于其他培养基; ② 添加在DCR中的3种蔗糖浓度中,35 g/L时的愈伤组织诱导率最高(92.01%)、褐化率最低(17.01%); ③ DCR添加35 g/L蔗糖情况下,9种植物生长调节剂组合中NAA 2.0 mg/L + 6-BA 1.5 mg/L组合的愈伤组织诱导率最高、褐化率最低、生长状态最佳; ④ 在选出的优化培养条件下,8种来源外植体中,从裸胚上切离的下胚轴的愈伤组织诱导率高、褐化率低,且增殖能力强,具备胚性愈伤组织的形态解剖特征。【结论】红松成熟胚愈伤组织诱导的优化培养条件为DCR +蔗糖35 g/L + NAA 2.0 mg/L+ 6-BA 1.5 mg/L,适宜外植体裸胚上切离的下胚轴。     

Effects of SiO2 on the preparation and metallurgical properties of acid oxidized pellets

The effects of SiO₂ content on the preparation process and metallurgical properties of acid oxidized pellets, including compressive strength, reduction, and softening–melting behaviors, were systematically investigated.Mineralogical structures, elemental distribution, and pore size distribution were varied to analyze the mechanism of the effects.The results show that with an increase in SiO₂ content from 3.51 wt%to 7.18 wt%, compressive strength decreases from 3150 N/pellet to 2100 N/pellet and reducibility decreases from 76.5% to 71.4%.The microstructure showed that pellets with high SiO₂ content contained more magnetite in the mineralogical structures.Additionally, some liquid phases appeared, which hindered the continuous crystallization of hematite.Also, the softening–melting properties of the pellets clearly deteriorated as the SiO₂ content increased.With increasing SiO₂ content, the temperature range of the softening–melting zone decreased, and the maximum differential pressure and the comprehensive permeability index increased significantly.When acid oxidized pellets are used as the raw materials for blast furnace smelting, it should be combined with high basicity sinters to improve the softening–melting behaviors of the comprehensive charge.