Strengthening iron enrichment and dephosphorization of high-phosphorus oolitic hematite using high-temperature pretreatment

The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.

Formation and characterization of metallic iron grains in coal-based reduction of oolitic iron ore

To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the re- duced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumula- tive frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol^-1, and 922.05, respec- tively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.

Migration behaviors and kinetics of phosphorus during coal-based reduction of high-phosphorus oolitic iron ore

To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA)and using the basic principle of solid phase mass transfer,respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction,and the migration process could be divided into three stages:phosphorus diffusing from the slag to the metallic interface,the formation of Fe P compounds at the slag metal interface and P diffusing from the slag metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature,while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.

Properties of a reaction-bonded β-SiAlON ceramic doped with an FeMo alloy for application to molten aluminum environments

An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.

Strengthening leaching effect of Carlin-type gold via high-voltage pulsed discharge pretreatment

A high-voltage pulsed discharge(HVPD)pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic.Optimal results of the pretreatment experiments were obtained at the following operating conditions:a spherical gap spacing of 20 mm,pulse number of 100,and voltage of 30 kV.The leaching rate of gold was increased by 15.65%via the HVPD pretreatment.The mass fraction of–0.5+0.35 mm and–0.35+0.1 mm was increased by 10.97%and 6.83%compared to the untreated samples,respectively,and the Au grade of–0.1 mm was increased by 22.84%.However,the superiority of the HVPD pretreatment would be weakened by prolonged grinding time.Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation,accompanying by some pore formation.More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment,with the contact area between the leaching reagent and ore increased,the leaching reaction rate enhanced and the leaching effect strengthened.

Comparisons of Image Quality and ADCs in Breath-Hold, Respiratory-Triggered and Free-Breathing DWI of Pancreas at 3-T

Objective: To compare image quality and apparent diffusion coefficients (ADC) of the normal pancreas parenchymas in breath-hold, respiratory-triggered and free-breathing diffusion weighted imaging (DWI) at 3.0-Tesla. Methods: DWI of the pancreas was performed at 3.0-Tesla in 21 healthy volunteers with breath-hold, respiratory-triggered and free-breathing using b-values of 0 and 500 s/mm2. For all three sequences, two readers assigned an image quality score to images at b0 and b500, and two independent readers measured ADCs for the head, body and tail of pancreas. Image quality scores and ADCs of pancreas in the three DWIs were compared. Results: For b0, image quality scores was not significantly different among the three sequences (p = 0.103). For b500, image quality score was significantly lower in free-breathing DWI than breath-hold or respiratory-triggered DWI (p = 0.000), and not significantly different between breath-hold and respiratory-triggered DWI (p = 0.212). Mean ADCs differed significantly among the anatomical regions with the lowest values measured in the pancreatic tail both at breath-hold and respiratory-triggered DWIs whereas no significant difference was found at free-breathing DWI. Conclusion: Breath-hold or respiratory-triggered technique provided DW images of pancreas with acceptable quality at 3.0-Tesla. Breath-hold is the preferred DWI technique for ADC measurements of pancreas.

Application of dexmedetomidine in different doses in combined with propofol in the painless colonoscopy in the elder patients

Objective:To explore the anesthetic effect of dexmedetomidine (Dex) in different doses in combined with propofol on the painless colonoscopy in the elder patients.Methods: A total of 60 elder patients who were admitted in our hospital from November 2016 to October 2017 for selective painless fiber colonoscopy were included in the study and divided into the low dose group and high dose group according to Dex dose. The micro-infusion pump was used to inject Dex 10 min before examination. The load capacity in the low dose group was 0.25 μg/kg, while in the high dose group was 0.75 μg/kg. The pump injection was completed within 10 min, then a continuous pump injection was performed in a speed of 0.5 μg/kg/h until the check off. After the completion of Dex pumping, propofol (1-1.5 mg/kg) was slowly injected. MAP, HR, and SpO2 before medication (T0), 5 min after inserting the endoscope (T1), and the time after the examination being finished (T2) were recorded, respectively. The bioelectrical impedance technique was used to continuously monitor SV, CO, and SVR. The awakening time, propofol dose, and discharge time were recorded.Results: The comparison of MAP, HR, and SpO2 at T0 between the two groups was not statistically significant. MAP, HR, SV, CO, and SVR at T1 and T2 were significantly lower than those at T0, while the comparison of SpO2 was not significantly changed. MAP at T1 in the high dose group was significantly higher than that in the low dose group, while HR at T1 and T2 was significantly lower than that in the low dose group. SV, CO, and SVR at T1 and T2 in the high dose group was significantly higher than those in the low dose group. The awakening time in the high dose group was significantly shorter than that in the low dose group, and the propofol dose was significantly less than that in the low dose group, while the comparison of discharge time was not significantly different. Conclusions: Application of Dex in a high dose in the painless colonoscopy in the elder patients can reduce the propofol dose, and will not increase the inhibiting effect on respiration and circulation.

Effect of lollipop sucking on the recovery of gastrointestinal function in children after congenital choledochal cyst excision: A randomized controlled trial

This study is aimed to evaluate the effect of lollipop sucking on the recovery of gastrointestinal function in children after congenital choledochal cyst excision.58 children who had undergone congenital choledochal cyst excision were randomly divided into two groups:the controlled group and the experimental group.Children in the experimental group were allowed to suck on strawberry lollipops for 20e30 min once every four hours beginning six hours after the operation.The recovery time of bowel sounds and anal defecation was recorded and compared between experimental and control groups.Compared with the controlled group the recovery times of bowel sounds(41.75±7.38 h vs.51.43±5.02;p<0.001)and anal defecation(64.32±14.69 h vs.79.17±14.91 h;p<0.001)were significantly shorter in the experimental group.Results of the present study indicate that Sucking of lollipops by children after choledochal cyst excision facilitates the recovery of bowel movement and relieves postoperative abdominal distension.

Accessory navicular in children

Accessory navicular(AN)is a developmental variation of the secondary ossification center of the navicular tuberosity.Ten percent of patients with AN will have pain symptoms that affect walking and life.As the AN changes the position of the posterior tibial tendon insertion,children with AN often have posterior tibial tendon function insufficiency and flexible flat foot.Surgical treatment is often required after failure of conservative treatment.This article reviewed the etiology,clinical manifestations,complications,and treatment methods of AN.

红土镍矿深度还原-磁选工艺富集镍和铁（英文）

提出采用"深度还原-磁选"工艺从红土镍矿中富集镍和铁。结果表明,在还原温度1275℃、还原时间50 min、渣相碱度1.0、配碳系数2.5和磁场强度72 kA/m的条件下,可得到镍品位为6.96%、回收率为94.06%和铁品位为34.74%、回收率为80.44%的镍铁精矿产品。分析表明,还原温度和时间影响深度还原发生的可能性及反应进度,渣相碱度影响炉料中渣的组成及镍铁元素从基体中溢出富集形成镍铁颗粒的速度,深度还原反应过程中镍铁颗粒生成、聚集并逐渐长大,经磁选后可有效促进镍铁矿物与脉石矿物分离。

焊接参数对Ti_2AlNb合金电子束焊接接头焊缝形状和残余应力的影响（英文）

采用有限元数值模拟方法预测Ti_2AlNb合金电子束焊接接头的残余应力,并通过实验加以验证。对比模拟与实验结果,本文的数值计算方法具有良好的精度。结果表明,焊缝中心区域呈现三向拉应力状态;其他焊接参数相同条件下,聚焦电流对焊缝形状及尺寸具有显著影响,从而影响焊接残余应力水平;对于Ti_2AlNb合金厚板电子束熔透焊接头,焊缝中心具有1000MPa左右的厚度方向应力;增大熔宽可降低厚度方向应力,进而降低接头裂纹倾向。

Ti2AlNb合金电子束焊接头再热裂纹的形成机理（英文）

为了阐明Ti2AlNb合金焊缝中再热裂纹的特点及形成机理,对Ti2AlNb电子束环焊接头进行一系列的焊后热处理,并采用OM、SEM、XRD和TEM对接头的宏观组织和显微组织进行分析。结果表明,当Ti2AlNb电子束环焊接头加热到700℃左右时,再热裂纹主要沿焊缝原始晶界产生。热处理过程中,当温度升高经过O相单相区时焊缝组织由焊态的B2相几乎完全转变为O相;当温度继续升高进入B2+O双相区后,沿着原始晶界优先发生O→B2+O相转变。在焊接残余应力和相变应力综合形成的高拉应力作用下,B2+O双相和O相基体的界面上开始产生再热裂纹。

经氰化处理的黄铜矿和方铅矿的浮选行为与机理（英文）

研究了CN^-与黄铜矿和方铅矿之间的吸附作用,然后在丁基黄药(BX)体系下研究了氰化吸附后的黄铜矿、方铅矿的浮选试验。结果表明,CN^-与两种矿物表面存在化学吸附作用,并可用Langmuir等温模型近似描述。在pH值为6.5,丁基黄药用量为4.0 mg/L的适宜条件下,氰化后的黄铜矿和方铅矿的浮选回收率可分别达到82.1%和63.9%。尽管CN^-降低了黄铜矿、方铅矿表面的接触角,但丁基黄药能够提高氰化矿物表面的疏水性。CN^-对黄铜矿的抑制作用大于方铅矿。在pH值为4.2~8.4时,BX与氰化后的方铅矿表面的相互作用存在静电吸附;BX在氰化后的黄铜矿表面的吸附作用为化学吸附。

蛇纹石及六偏磷酸钠对硼镁石浮选的影响（英文）

为提高硼镁石浮选回收率,使用六偏磷酸钠减小蛇纹石对浮选的不利影响。通过浮选试验、zeta电位测试、傅里叶红外光谱分析、XPS分析及DLVO理论等手段,研究蛇纹石粒度、含量以及六偏磷酸钠(SHMP)对硼镁石浮选的影响,并对矿物颗粒间的相互作用以及六偏磷酸钠的作用机理进行分析。结果表明,蛇纹石与硼镁石颗粒间易发生团聚作用,且蛇纹石粒度对硼镁石浮选结果影响十分显著。与粗粒级蛇纹石相比,粒径小于38μm的蛇纹石能显著降低硼镁石的回收率。加入SHMP后,蛇纹石对硼镁石浮选的不利影响得到明显减弱。机理研究表明,SHMP能影响蛇纹石与硼镁石矿物表面电荷,从而阻碍颗粒间团聚的发生,使矿物颗粒在矿浆中呈良好的分散状态,有利于硼镁石的浮选。此外,SHMP通过氢键与化学吸附作用于蛇纹石表面,并生成一种络合物使蛇纹石的可浮性降低。

Geochemical characteristics and genetic mechanism of the high-N2 shale gas reservoir in the Longmaxi Formation, Dianqianbei Area, China

As an important pilot target for shale gas exploration and development in China,the Longmaxi Formation shale in the Dianqianbei Area is characterized by high content of nitrogen,which severely increases exploration risk.Accordingly,this study explores the genesis of shale gas reservoir and the mechanism of nitrogen enrichment through investigating shale gas compositions,isotope features,and geochemical characteristics of associated gases.The high-nitrogen shale gas reservoir in the Longmaxi Formation is demonstrated to be a typical dry gas reservoir.Specifically,the alkane carbon isotope reversal is ascribed to the secondary cracking of crude oil and the Rayleigh fractionation induced by the basalt mantle plume.Such a thermogenic oil-type gas reservoir is composed of both oil-cracking gas and kerogen-cracking gas.The normally high nitrogen content(18.05%-40.92%) is attributed to organic matter cracking and thermal ammoniation in the high-maturity stage.Specifically,the high heat flow effect of the Emeishan mantle plume exacerbates the thermal cracking of organic matter in the Longmaxi Formation shale,accompanied by nitrogen generation.In comparison,the abnormally high nitrogen content(86.79%-98.54%) is ascribed to the communication between the atmosphere and deep underground fluids by deep faults,which results in hydrocarbon loss and nitrogen intrusion,acting as the key factor for deconstruction of the primary shale gas reservoir.Results of this study not only enrich research on genetic mechanism of high-maturity N_@ shale gas reservoirs,but also provide theoretical guidance for subsequent gas reservoir resource evaluation and well-drilling deployment in this area.

Puerarin exhibits greater distribution and longer retention time in neurons than astrocytes in a co-cultured system

The phytoestrogen puerarin has been shown to protect neurons and astrocytes in the brain, and is therefore an attractive drug in the treatment of Alzheimer’s disease, Parkinson’s disease and cerebral ischemia. Whether puerarin exhibits the same biological processes in neurons and astro-cytesin vitro has rarely been reported. In this study, cortical neurons and astrocytes of newborn Sprague-Dawley rats were separated, identiifed and co-cultured in a system based on Transwell membranes. The retention time and distribution of puerarin in each cell type was detected by lfuorescence spectrophotometry and lfuorescence microscope. The concentration of puerarin in both co-cultured and separately cultured neurons was greater than that of astrocytes. Puerarin concentration reached a maximum 20 minutes after it was added. At 60 minutes after its addi-tion, a scant amount of drug was detected in astrocytes; however in both separately cultured and co-cultured neurons, the concentration of puerarin achieved a stable level of about 12.8 ng/mL. The results indicate that puerarin had a higher concentration and longer retention time in neu-rons than that observed in astrocytes.

Al-Mg合金孪晶变形的第一性原理研究（英文）

镁元素可以降低铝的本征层错能,因而Al-Mg合金被认为具备孪晶变形的潜力。然而在多种大变形Al-Mg合金中很难发现变形孪晶。为了探究Al-Mg合金的孪晶变形潜能,采用第一性原理计算研究镁和空位对铝广义层错能的影响。研究发现Mg和空位均具有层错Suzuki偏析特性,并且会降低Al的本征层错能。但是随着镁含量的提高,铝的本征层错能不会持续降低,孪晶特性参数τa也不会持续升高。基于Al-Mg合金的孪晶特性参数τa,我们预测即使在高固溶镁含量下,Al-Mg合金依然很难发生孪晶变形。镁和空位所引起的本征层错能的降低在一定程度上能够提高大变形Al-Mg合金的加工硬化速率并且促进变形带的形成。

Effect of dexmedetomidine on inflammatory factors and immune function in elderly patients undergoing laparoscopic radical resection of colorectal cancer

Objective:To investigate the effect of dexmedetomidine on inflammatory factors and immune function in elderly patients undergoing laparoscopic radical resection of colorectal cancer. Methods: From April 2016 to April 2017, 86 cases of elderly laparoscopic radical resection of colorectal cancer in our hospital were selected and randomly divided into the observation group and the control group. 2 groups of patients were open venous access, oxygen mask, monitoring heart rate (HR), blood pressure (BP), electrocardiogram (ECG), oxygen saturation (SpO2), bispectral index (BIS), after induction of anesthesia, the observation group was given dexmedetomidine 0.4 g/kg to 20 mL of normal saline control. Group of 20 mL saline, 15 min infusion is completed, and the observation group of dexmedetomidine in 0.4 g/kg - h continuous infusion of normal saline control group, continuous infusion, until the end of surgery. Before induction of anesthesia (T0), 2 h after operation beginning (T1), at the end of operation (T2), 24 h after operation (T3) in venous blood, using ELISA method for the determination of serum interleukin-2 receptor (sIL-2R) and interleukin-6 (IL-6), tumor necrosis factor alpha (the level of TNF-alpha);on preoperative and postoperative 4 h, 12 h, 24 h after operation in venous blood serum epinephrine ELISA method (E), norepinephrine (NE), endothelin-1 (ET-1) level;on preoperative and postoperative 4 h, 12 h after surgery, 24 h venous blood flow cytometry determination of CD3+, CD4+, CD8+, CD4+/CD8+.Results:compared with before operation, the observation group after 4 h, 12 h, 24 h NE, and the lower control group E, NE and ET-1 increased, the observation group after 4 h, 12 h, 24 h E, NE, ET-1 lower than that of the control group;compared with T0, 2 patients in group T2, T3 sIL-2R, IL-6, TNF-alpha were increased, the observation group T2, T3 sIL-2R, IL-6, TNF- were lower than that of the control group;compared with the preoperative, 2 group after 4 h, 12 h, 24 h CD3+, CD4+, CD8+ and CD4+/CD8+ decreased, the observation group after 4 h, 12 h, 24 h CD3+, CD4+, CD8+, CD4+/CD8+ higher than those in the control group.Conclusion: Dexmedetomidine has a good analgesic effect on elderly patients undergoing laparoscopic radical resection of colorectal cancer. It can effectively relieve the stress reaction and inflammatory reaction during perioperative period, and effectively improve the immune function of the patients.

气凝胶隔热层隔热性能计算与试验验证

为了研究气凝胶隔热层的隔热效果,首先基于三维热流固耦合分析方法,通过数值计算手段对气凝胶隔热层的隔热性能进行了计算,随后在进口为高温条件下进行了隔热性能试验,获得了隔热层在不同温度、不同燃气流量下的隔热特性规律。采用Matlab软件对内外壁温度之间的关联关系进行了数学公式拟合,并对前期数值计算结果和试验结果进行了对比,证明数值计算的正确性。

Effect of dexmedetomidine combined with propofol on stress response and early cognitive function in hypertensive patients undergoing painless gastroscopy

Objective:To investigate the effect of dexmedetomidine combined with propofol on stress response and early cognitive function in hypertensive patients undergoing painless gastroscopy. Methods: A total of 70 cases of hypertensive patients undergoing painless gastroscopy from March 2016 to March 2017 were selected as the subjects. They were randomly divided into the observation group and the control group. The control group was injected with physiological saline before injection and injected with propofol 2 mg/kg. The observation group was injected with propofol 0.4 g/kg before injection, and 1 mg/kg by intravenous injection of propofol. 2 groups of patients before administration (T0), after administration (T1), gastroscopy (T2), gastroscope examination at the end of the 10 min (T3) collected venous blood, plasma epinephrine by radioimmunoassay (E), norepinephrine (NE), cortisol (COR) levels of T0 records;T1, T2, T3 at the time of breathing (HR), mean arterial pressure (MAP);after 5 min, 30 min, 3 h, 6 h was evaluated with mini mental state examination (MMSE) to evaluate the cognitive function in early stage.Results: 2 groups of patients with T1, NE, COR levels of plasma E and T0 no significant difference, T2, T3, NE, COR and plasma E levels higher than the T0 level, the observation group T2, T3, NE, plasma E COR levels lower than the control group, there was statistical significance the difference between the 2 groups;the control group T1 HR is slower than T0, MAP less than T0, T2, T3 HR faster than T0, MAP is higher than T0, and the observation group HR and MAP each time point did not change significantly between the 2 groups was statistically significant the difference;after 5 min and 30 min compared with the preoperative MMSE score decreased 1 D, 3 h after operation, the 6 h gradually increased, but the observation group after 3 h MMSE score higher than the control group, the difference was statistically significant.Conclusion: Dexmedetomidine combined with propofol can reduce the stress reaction of patients with hypertension during painless gastroscopy, and reduce the early understanding of the occurrence of dysfunction, which is worthy of clinical promotion.