The Role of Rare Earth (Y) Ions on the Structural,Magnetic and Mechanical Properties of Co–Mg Nanoferrites

The current paper is an effort to investigate the impact of rare earth yttrium on magnetic and mechanical properties of novel Co–Mg–Y nanoparticles. A series of ferrite nanoparticles, with a constant amount of cobalt and magnesium, substituted with various amounts of Y³⁺ as Co_0.7Mg_0.3Y_xFe_2-xO₄ (labeled as CMYF nanoferrites) were prepared and studied. The prepared CMYF samples were well investigated for structure and morphology utilizing x-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), and Fourier-transform infrared (FTIR) analysis. The crystallite size of CMYF nanoferrites introduced an abnormal behavior with further Y³⁺ substitution, ranging from 33.33 to 66.89 nm. The nanoferrite Co_0.7Mg_0.3Y_0.08Fe_1.92O₄ (x?=?0.08) has the highest coercivity (1410 G) within all CMYF samples, with increasing ratio 36.10% than the pristine Co–Mg nanoferrite. Also, the nanoferrite Co_0.7Mg_0.3Y_0.1Fe_1.9O₄ (x?=?0.1) has the highest resistance to uniform compression with increasing ratio 8.21% than the pristine nanoferrite. Shear and Young moduli introduced a peculiar trend: decrease regularly for 0.0?≤?x?≤?0.08 and then increase for the nanoferrite with x?=?0.1. Poisson’s ratio values confirmed that all CMYF nanoferrites are stable, isotropic, and linear elastic materials. Hosselman and Fulrath’s model was utilized to correct elastic moduli to zero porosity, which confirmed that porosity is a significant parameter for CMYF nanoferrite elastic moduli determination. Therefore, we conclude that Co_0.7Mg_0.3Y_0.08Fe_1.92O₄ nanoferrite can be utilized in storage media applications and Co_0.7Mg_0.3Y_0.1Fe_1.9O₄ nanoferrite in diverse ferrite standard mechanical applications.

     

The Theoretical Summary and Mathematics Expression on the Regulation of Life in Meridian（Jingluo经络）Science

The meridian（Jingluo经络）is a core principle of traditional Chinese medicine．The meridian plays a central role in the regulation of human health and vitality．In the past５０years,the scientific evidence has been gathered via our physiological experiments to confirm the biological basis of the human meridian pathway phenomenon．Meridian Science has been established as a new branch of natural science to advance and promote the study of this important phenomenon for human life．In this paper,the authors describe the theoretical concept of the meridian and mathematics expression,its relationship to an efficient meridian circadian cycle,and its significance to human life．     

Effects of Sc(Zr) on the microstructure and mechanical properties of as-cast Al–Mg alloys

Both the addition of 0.6% Sc and simultaneous addition of 0.2% Sc and 0.1% Zr exerted a remarkable effect on grain refinement of as-cast Al–Mg alloys, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the formation of primary particles, which acted as heterogeneous nucleation sites for α-Al matrix during solidification. Primary particles formed in Al–Mg–Sc–Zr alloy could be identified as the eutectic structure consisting of multilayer of ‘Al₃(Sc,Zr)?+?α-Al?+?Al₃(Sc,Zr)’, with a ‘cellular-dendritic’ mode of growth. In addition, an attractive comprehensive property of as-cast Al–5Mg alloy due to the addition of 0.2% Sc and 0.1% Zr was obtained.     

Fe-Site Doping and Spin Effects on Phonon and Superconductivity in SrFe1−x Co x AsF (x=0,0.125)

First-principles calculations are performed for phonon spectra, phonon density of states and electron-phonon coupling constants of SrFe_1?x Co _x AsF (x=0,0.125) with tetragonal nonmagnetic (NM) and orthorhombic striped antiferromagnetic (SAF) structures. It is found that Co-doping in Fe-site harden phonons in NM structure and soften phonons in SAF structure, and spin interaction makes phonons soften in evidence. Electron-phonon coupling is enhanced by both doping and spin interaction in Fe-site, but does not large enough to produce experimental superconductivity, which rules out phonon mechanism superconductivity in SrFe_1?x Co _x AsF.     

Characteristics of In_(0.52)Al_(0.48)As Grown on InP(100) Substrates by Molecular Beam Epitaxy: Growth Optimisation and Effects of Si Doping

Growth of In0.52Al0.48As epilayers on InP (100) substrates by molecular beam epitaxy at a wide range of substrate tempreatures (470~550℃) and at different Si doping levels has been carried out. Low temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) analyses shaw a strong dependence of the PL and XRD linewidths, XRD intensity ratio (Lepi/Isub), and lattice-mismatch on the substrate temperature. The X-ray diffraction peaks of samples grown at law temperatures show a composition of smaller peaks, indicating the presence of disorder due to alloy clustering. Raman scattering measurements of the same samples show an additional higher energy mode at 273 cm-1 in addition to the InAs-like and AlAs-like longitudinal-optic (LO) phonon modes. Samples doped with Si show an inverted S-shaped dependence of the PL peak energy variation with the temperature which weakens at high doping levels due to a possible reduction in the donor binding energy. Supported be observations of a reduction in both the AlAs-like and InAs-like LO phonon frequencies and a broadening of the LO phonon line shape as the doping level is increased, the PL intensity also shows in increasing degrees at higher doping levels, a temperature dependence which is characteristic of disordered and amorphous materials.     

Computer-aided Prediction of the ZrO2 Nanoparticles’ Effects on Tensile Strength and Percentage of Water Absorption of Concrete Specimens

In the present paper,two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing ZrO2 nanoparticles have been developed at different ages of curing.For building these models,training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted.The data used in the multilayer feed forward neural networks models and input variables of genetic programming models were arranged in a format of eight input parameters that cover the cement content,nanoparticle content,aggregate type,water content,the amount of superplasticizer,the type of curing medium,age of curing and number of testing try.According to these input parameters,in the neural networks and genetic programming models,the split tensile strength and percentage of water absorption values of concretes containing ZrO2 nanoparticles were predicted.The training and testing results in the neural network and genetic programming models have shown that two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing ZrO2 nanoparticles.It has been found that neural network(NN) and gene expression programming(GEP) models will be valid within the ranges of variables.In neural networks model,as the training and testing ended when minimum error norm of network gained,the best results were obtained and in genetic programming model,when 4 genes were selected to construct the model,the best results were acquired.Although neural network have predicted better results,genetic programming is able to predict reasonable values with a simpler method rather than neural network.     

Influence of the Structure of (О-Phenylenoxymethylene)diphosphine Dioxides on Their Extraction Ability to U(VI), Th(IV), and REE(III) in Nitric Acid Media

Radiochemistry - Extraction of microquantites of U(VI), Th(IV), and REE(III) from nitric acid solutions with solutions of (o-phenyleneoxymethylene)diphosphine dioxides with phenyl and butyl...     

Effects of Cu and Al on the crystal structure and composition of η (MgZn2) phase in over-aged Al–Zn–Mg–Cu alloys

Heat treatable Al–Zn–Mg alloys can be strengthened by the precipitation of second phase particles. In this paper, Al–6.57%Zn–2.83%Mg and Al–6.57%Zn–2.83%Mg–3.92%Cu alloys (in wt%) in T7 state (140 °C for 96 h) have been prepared. The effects of Cu and Al on the concentration and structure of equilibrium η (MgZn₂) phase have been investigated by high resolution transmission electron microscopy, aberration-corrected scanning transmission electron microscopy, selected election diffraction pattern simulations, and first-principles calculations. The effects of Cu and Al substitution on the diffraction characteristics of the η phase and the general rule of Cu and Al substitution in the η phase have been discussed.     

Effects of Li addition on the corrosion behaviour and biocompatibility of Mg(Li)–Zn–Ca metallic glasses

Magnesium alloys with suitable corrosion behaviour and good mechanical properties are desired for biodegradable materials. In the current study, novel Mg–Li-based metallic glasses (MGs) demonstrate potential clinical applications as implantable biodegradable materials. The amorphous structure of MGs provides suitable elastic modulus with human bone. The enhanced corrosion resistance of MGs realises a uniform corrosion process, as well as maintains a stable acid-based environment, and increases cell proliferation. A schematic model is proposed to illustrate the corrosion mechanisms of MGs. Adding Li significantly improves the corrosion resistance of MGs. Both the indirect cytotoxicity and direct cell culture assays are conducted using transfected osteoblasts (hFOB) cells. Results show that the novel Mg–Li–Zn–Ca MGs have good biocompatibility.     

缓凝剂硼砂对磷酸镁水泥水化硬化特性的影响

为了探讨缓凝剂硼砂(B)对磷酸镁水泥(MPC)的作用机理,测试和分析了不同掺量硼砂(B)的磷酸镁水泥(MPC)浆体的凝结时间、pH值、体系温度以及硬化体的强度和微观结构。结果表明:硼砂在一定掺量范围内对磷酸镁水泥(MPC)浆体有较明显的吸热降温促进作用和调节pH值作用,两种作用均可减慢浆体的水化反应速度且进一步影响硬化体的微观结构形貌和强度。由此推论硼砂在磷酸镁水泥(MPC)浆体中,除在MgO表面形成保护膜外,还通过降低体系温度和调节浆体pH值进而减慢水化反应速度来延缓浆体的凝结,随着硼砂(B)掺量的变化,不同因素起主导作用。     

低水灰比对硅酸盐水泥水化程度的影响

研究了低水灰比硅酸盐水泥的水化程度，并利用XRD和SEM分析了其水化产物的微观结构。结果表明在低水灰比条件下，水泥的水化程度较低，其硬化水泥浆体中存在较多的未水化水泥；同时由于自身的密实性增强和体系的低孔隙率，使水泥水化产物的结晶、生长情况也受到影响。     

活化煤矸石对水泥水化的影响

研究了活化煤矸石-氢氧化钙体系的水化热、水化产物成分以及活化煤矸石水泥体系的水化过程、水化产物的微结构,结果表明,在石膏的激发下,活化煤矸石能够发生二次水化,与Ca（OH）2反应形成钙矾石、水化硅酸钙、水化铝酸钙等有利于提高水泥石强度的水化产物;活化煤矸石水泥硬化浆体中Ca（OH）2的含量在水化3d时最多,而后随龄期逐渐减少;阐明了活化煤矸石能够降低水化产物中氢氧化钙的含量、抑制氢氧化钙晶体的生长和聚集,并改善水泥石结构．     

水泥材料成型过程对硬化体结构与性能的影响

新拌水泥混凝土浆体常被抽象为含水的颗粒悬浮结构,这种抽象将复杂的成型过程过于简化,存在许多难以预知和不可量化的因素,给水泥基材料科学体系的架构造成技术障碍。分别综述了混凝土成型、水泥净浆成型共同存在的组分材料离析、泌水和夹杂气泡等缺陷,分析了组分分散效果对水泥水化硬化体结构与性能的影响。将水泥颗粒堆积体与其水化硬化体制备结合起来,通过压制绝干水泥颗粒堆积结构,再毛细吸水成型水泥水化硬化体,可以最大程度避免微观层面的离析、泌水及夹杂气泡等不易量化的因素对成型的影响,有利于模型化研究非均质、多层次复杂结构的演变与性能调控。     

Use of rice straw as biosorbent for removal of Cu(II), Zn(II), Cd(II) and Hg(II) ions in industrial effluents

Adsorption experiments were carried out using waste rice straw of several kinds as a biosorbent to adsorb Cu(II), Zn(II), Cd(II) and Hg(II) ions from aqueous solutions at room temperature. To achieve the best adsorption conditions the influence of pH and contact time were investigated. The isotherms of adsorption were fitted to the Freundlich equation. Based on the experimental data and Freundlich model, the adsorption order was Cd(II) > Cu(II) > Zn(II) > Hg(II) on the rice straw. This quick adsorption process reached the equilibrium before 1.5 h, with maximum adsorptions at pH 5.0. Thermodynamic aspects of the adsorption process were investigated. The biosorbent material was used in columns for the removal of ions Cu, Zn, Cd and Hg of real samples of industrial effluent and its efficiency was studied.     

含钡硫铝酸盐水泥的水化动力学与热力学研究

采用XRD和等温微量热法测试计算含钡硫铝酸盐水泥的水化动力学和热力学过程。结果表明,含钡硫铝酸盐水泥的水化过程主要受扩散过程控制,水化速率变化模式与铝酸钙、硅酸盐水泥类似。水化过程分为加速期、减速期和衰减期:在加速期,水化反应受成核反应控制,属自催化反应;从减速期开始,水化物在颗粒表面形成水化物薄膜,水化反应阻力加大,速率减缓;进入衰减期,水化反应完全受扩散过程控制。     

Removal of Zn(II), Cu(II), Ni(II), Ag(I) and Cr(VI) present in aqueous solutions by aluminium electrocoagulation

The performance of an electrocoagulation system with aluminium electrodes for removing heavy metal ions (Zn2+, Cu2+, Ni2+, Ag+, Cr2O7(2-)) on laboratory scale was studied systematically. Several parameters - such as initial metal concentration, numbers of metals present, charge loading and current density - and their influence on the electrocoagulation process were investigated. Initial concentrations from 50 to 5000 mg L(-1) Zn, Cu, Ni and Ag did not influence the removal rates, whereas higher initial concentrations caused higher removal rates of Cr. Increasing the current density accelerated the electrocoagulation process but made it less efficient. Zn, Cu and Ni showed similar removal rates indicating a uniform electrochemical behavior. The study gave indications on the removal mechanisms of the investigated metals. Zn, Cu, Ni and Ag ions are hydrolyzed and co-precipitated as hydroxides. Cr(VI) was proposed to be reduced first to Cr(III) at the cathode before precipitating as hydroxide.     

水泥熟料固化重金属Cu2+和Zn2+及水化浸出行为分析

危废处理是当前的热点问题,水泥窑协同处置作为一种有效的处理方式,逐步为社会所接受。多数的危废中包含Cu²⁺和Zn²⁺,文章研究了危废中重金属Cu²⁺和Zn²⁺在水泥熟料中的固化性能和在熟料中的分布,并探讨了重金属在水泥净浆中的浸出行为和环境安全性。通过熟料易烧性X射线衍射(XRD),矿物相分离萃取,浸出实验得出:Cu²⁺和Zn²⁺均改善了熟料易烧性;Cu²⁺促进了C₄AF的生成,同时也促进了C₃S晶粒的生长,并固溶在其中;Zn²⁺与熟料形成新的矿物相Ca₁₄Al₁₀Zn₆O₃₅。通过相对分布系数(D)和分配系数(K_f)说明Cu²⁺主要分布在硅酸盐相中,硅酸盐相固化Cu²⁺的能力强于中间相;Zn²⁺主要分布在中间相中,中间相固化Zn²⁺的能力强于硅酸盐相。掺量为2.0%的Cu²⁺和Zn²⁺在水泥净浆7 d龄期的浸出浓度最大,分别为1.724和0.387 mg·L^-1。水泥熟料固化Cu²⁺和Zn²⁺在水泥使用过程中不会对环境造成二次污染。     

含锶磷灰石骨水泥浆体的pH值及其固化体的体外细胞毒性评价

在线测量了自制含锶羟基磷灰石骨水泥(Sr-CPC)浆体在水化过程中的pH值实时变化以及各固化体在培养液中浸泡不同时间后其浸提液的pH值,并利用MTT比色法评价了该水泥固化体的体外细胞毒性.XRD与FTIR分析表明,固化体在SBF中浸泡24h后,水化产物为锶钙羟基磷灰石固溶体,而且该固溶体中含有与骨磷灰石类似的CO₃^2-;各水泥浆体pH值的在线测量表明,不同含锶量水泥浆体的pH基本在6.5-7.8之间变化,接近中性;体外细胞毒性试验表明,不同含锶量水泥固化体的细胞毒性为0或1级,且细胞毒性与各水泥固化体浸提液的浓度、作用时间有一定的关联性.     

Recovery of Cu(II) and Cd(II) by a chelating resin containing aspartate groups

A chelating resin, crosslinked poly(glycidyl methacrylate-aspartic acid) (PASP), was synthesized by anchoring sodium aspartate to crosslinked poly(glycidyl methacrylate) for the recovery of Cu2+ and Cd2+ from aqueous solutions. The resin was characterized by Fourier transform infrared spectroscopy, scanning electron microscope and mass balance. In non-competitive conditions, the adsorptions tended toward equilibrium at 60 min and the equilibrium adsorption capacities were 1.40 and 1.28 mmol/gPASP for Cu2+ and Cd2+, respectively. The adsorption isothermals of the metal ions by PASP followed the Freundlich isotherm. Adsorption of Cu2+ was affected slightly in the presence of NaNO3 (0-0.3M) but the uptake of Cd2+ decreased significantly in the same condition. Except pH> or =4.0, the adsorption capacity of each metal ion decreased with lowering of solution pH. The reusability of PASP in adsorptions was investigated for five successive adsorption-desorption operations. When the pH of Cu2+/Cd2+ mixture was 2 or 2.5, the competitive adsorption tests confirmed this resin had good adsorption selectivity for Cu2+ with the coexistence of Cd2+.