原子吸收法测定硅藻土中的铁,钙和镁

通过Al、SiO_2、HClO_4对Fe、Ca、Mg原子吸收法测定干扰的研究,对仪器工作条件、溶样方法的研究,建立了原子吸收法测定硅藻土中Fe、Ca、Mg的分析方法。此法测定Fe、Ca、Mg的相对标准偏差分别是Fe<2.0%、Ca<9.0%、Mg<10.0%,三元素回收率均在94-106%之间。     

The 7-line luminescence spectrum of (Neeh) in GaP:N,a correction

A new interpretation is given for the weak, green photoluminescence in GaP:N. The high energy part of this spectrum is due to the zero phonon recombination of excitons bound to neutral carbon and magnesium acceptors. The low energy part involves emission lines of unknown origin and a partial overlap of grating ghosts due to the nitrogen A-line.     

In situ analysis of magnesium alloy using a standoff and double-pulse laser-induced breakdown spectroscopy system

To monitor the components of molten magnesium alloy during the smelting process in real time and online, we designed a standoff double-pulse laser-induced breakdown spectroscopy (LIBS) analysis system that can perform focusing, collecting and imaging of long-range samples. First, we tested the system on solid standard magnesium alloy samples in the laboratory to establish a basis for the online monitoring of the components of molten magnesium alloy in the future. The experimental results show that the diameters of the focus spots are approximately 1 mm at a range of 3 m, the ablation depth of the double-pulse mode is much deeper than that of the single-pulse mode, the optimum interpulse delay of the double pulse is inconsistent at different ranges, and the spectral intensity decays rapidly as the range increases. In addition, the enhancement effect of the double pulse at 1.89 m is greater than that at 2.97 m, the maximum enhancement is 7.1-fold for the Y(I)550.35-nm line at 1.89 m, and the calibration results at 1.89 m are better than those at 2.97 m. At 1.89 m, the determination coefficients (R²) of the calibration curves are approximately 99% for Y, Pr, and Zr; the relative standard deviations (RSDs) are less than 10% for Y, Pr, and Zr; the root mean square errors (RMSEs) are less than 0.037% for Pr and Zr; the limits of detection (LODs) are less than 1000 ppm for Y, Pr, and Zr; and the LODs of Y, Pr, and Zr at 2.97 m are higher than those at 1.89 m. Additionally, we tested the system on molten magnesium alloy in a magnesium alloy plant. The calibration results of the liquid magnesium alloy are not as favorable as those of the sampling solid magnesium alloys. In particular, the RSDs of the liquid magnesium alloy are approximately 20% for Pr and La. However, with future improvements in the experimental conditions, the developed system is promising for the in situ analysis of molten magnesium alloy.     

重离子诱变酵母培养基的优化与研究

利用12C6+离子诱变技术对面包酵母菌种进行诱变,得到一株粗蛋白含量达到55% 以上的菌株,借助Minitab16.0,采用Plackett-Burman 实验设计法及响应面分析法,对诱变后面包酵母菌发酵培养基的成分进行了优化,得到3 个最为显著的主要影响因子:葡萄糖、酵母抽提物和硫酸镁。利用最陡爬坡实验逼近最大响应区域后,利用Box-Behnken 实验设计及响应面分析法进行回归分析。通过求解回归方程,得到优化发酵的条件为,葡萄糖:11.03 g/L、酵母抽提物:6.53 g/L、硫酸镁:5.59 g/L。面包酵母生物量为4.84 g/L,相比未进行优化时的生物量提高了15%。A mutant bread yeast strain with high protein content of 55% was gained by use of 12C6+ ions. The MINITAB 16.0 software, Plackett-Burman experimental design and response surface methodology were applied to optimize the culture medium for the irradiated yeast. The most important three factors which influenced the culture results were identified as glucose, magnesium sulphate and yeast extract. The path of the steepest ascent was undertaken to approach the optimal region of the three significant factors. Box-Behnken design and response surface methodology were used for the regression analysis. Finally, the optimal fermentation conditions were identified as glucose 11.03 g/L, yeast extract 6.53 g/L and magnesium sulphate 5.59 g/L by the regression analysis. It was found that the biomass of the bread yeasts reached 4.84 g/L and increased by 15% compared to original conditions.     

Analysis of the possibility of the spin-orbit origin of surface state splitting in thin Mg(0001) layers on W(110) and Mo(110)

A set of magnesium films ranging in thickness from submonolayer to a few tens of atomic layers grown on single-crystal W(110) has revealed film-thickness dependent splitting of states localized energywise close to the magnesium surface state. Literature refers to several models describing the origin of this splitting; in one case, it is treated as substrate-induced spin-orbit splitting, and in another, as due to formation of nondegenerate pairs of even and odd surface states penetrating deep into the film bulk. The proposed models draw upon studies of films more than five monolayers thick. A comparative investigation of the Mg/W(110) and Mg/Mo(110) systems has been carried out for magnesium films of different, starting from submonolayer, thicknesses, which did not substantiate the spin-orbit origin of this splitting and suggests instead formation on the substrate-film interface of hybridized states, with their variation with thickness being assigned to variation in the contribution due to the magnesium surface states. Original Russian Text ? A.M. Shikin, D.E. Marchenko, N.A. Vinogradov, G.V. Prudnikova, A.G. Rybkin, V.K. Adamchuk, O. Rader, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 3, pp. 572–583.     

Nuclear charge radii of (21-32)Mg

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on (24)Mg and (32)Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.     

FT-NIR法测定烟草中的镁

应用傅里叶变换近红外光谱分析技术,采用偏最小二乘法建立了近红外光谱与烟草中镁含量的数学模型。经检验,近红外测定值与化学测定值间的平均相对误差为9.09%。该技术简捷、快速、精密度高,可用于烟草中镁的快速测定。     

在铝镁合金的疲劳载荷过程中溶质原子与位错的交互作用

本文进行了淬火状态的、含0.52,0.91,3.46和5.15％Mg的铝合金的扭转疲劳试验,测定了相应的ΔE-N曲线和T_m-N曲线。实验结果指出,对于含镁量为0.52,0.91％的试样来说,当表面扭应变较小时,ΔE在起始时,随着应力循环数的增加而下降。当表面扭应变增大时,ΔE-N曲线始而变平,继而上升,直至达到一较高值才稳定下来。当试样中的含镁量为3.46％时,在扭应变不太大时,ΔE-N曲线的变化情况与Al-4％Cu合金的相象,不过当扭应变足够大时,ΔE起始时上升,并且经过一个峯值又下降。当含镁量增至5.15％时,ΔE-N曲线的表现已完全与Al-4％Cu合金的相象,在所用的最高表面扭应变下也并不表现出明显的峯值。对于所用的各种成分的试样来说,最大抗扭矩T_m起始总是上升的。上述结果都可以根据溶质镁原子在疲劳过程中渐渐进入位错,形成气团来解释。可以认为,在铝镁合金的情形,产生ΔE的因素以及影响ΔE的大小的因素,对于疲劳载荷的起始阶段来说,可能都主要是由于气团的作用。当含镁量较低时,对于足够高的表面扭应变来说,气团较为松动,位错能够拖着气团运动,从而需要作功,使ΔE和T_m都上升。但当合镁量较高时,或表面扭应变不太大时,在疲劳一起始就形成了能够对于位错起钉扎作用的足够浓的气团。继续进行疲劳时,进入位错的溶质原子将使位错的动性进一步降低,导致ΔE起始下降,T_m起始上升。此外,还对于经过不同时效处理的Al-0.52％Mg和Al-3.46％Mg合金进行了疲劳试验,观测到应变时效现象,这与上述的溶质原子气团模型相合。     

Dry sliding tribological behavior of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The dry sliding tribological behavior of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at energy density of 3.4 J/cm² with 10 shots is investigated by dry sliding wear tests in order to explore the effect of HIPIB irradiation on tribological property of magnesium alloy. Surface morphologies, composition and structure of the irradiated AZ31 magnesium alloys are examined by electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The results indicated that HIPIB irradiation led to the increase in surface microhardness and the reduction in friction coefficient and wear rate. Wear rate for both the original and the irradiated samples increased with increasing sliding load from 0.1 to 0.5 N. The transition from severe metallic wear to mild oxidative wear induced by HIPIB irradiation was observed by a combined analysis in surface morphology and chemical composition of wear tracks, mechanically mixed materials and wear debris, which is mainly attributed to the significant increase in microhardness resulting from grain refinement on the irradiated surface. In addition, defects induced by HIPIB irradiation promoted the diffusion of oxygen during sliding wear and therefore led to the formation of compact mixed materials and protective films on the wear tracks surface, which also contributes to the transition in wear mechanism of AZ31 magnesium alloy induced by HIPIB irradiation.     

多波长分光光度法同时测定钙和镁

本文提出了多波长线形回归分光光度法同时测定饮用水中的钙和镁 ,考察了最佳实验条件 ,并对钙、镁合成样品进行测定 ,其相对标准偏差分别为 1.17%和 1.95 % ,相对误差分别为± 0 .6 %和± 1.2 % ,对饮用水进行测定并进行加标回收实验 ,钙和镁回收率分别为 98.9%— 10 1.2 % ,99.6 %— 10 3.2 %。本方法简便、准确 ,结果令人满意     

Electroless deposition of Ni-W-P coating on AZ91D magnesium alloy

Ternary Ni-W-P alloy coating was deposited directly on AZ91D magnesium alloy by using an alkaline-citrate-based baths. Nickel sulfate and sodium tungstate were used as metal ion sources, respectively, and sodium hypophosphite was used as a reducing agent. The pH value of the electroless bath was tailored for magnesium alloy. The coating was characterized for its structure, morphology, microhardness and the corrosion properties. SEM observation showed the presence of dense and coarse nodules in the ternary coating. EDS analysis showed that the content of tungsten in the Ni-W-P alloy was 4.5 wt.%. Both the electrochemical analysis and the immersion test in 10% HCl solution revealed that the ternary Ni-W-P coating exhibited good corrosion resistance properties in protecting the AZ91D magnesium alloy.     

N‐σ versus π configuration in mono‐ and bis‐pyrrole and imidazole derivatives of alkaline earth metals

A theoretical study of the preferred N‐σ or π configuration of the mono‐ and bis‐pyrrole and imidazole derivatives of alkaline earth metals has been carried by means of DFT and ab initio methods, up to G2 computational level. The energetic results show that the beryllium derivatives prefer the N‐σ configuration while the calcium ones prefer the π one. In the case of magnesium, both configurations present similar stability. The calculated dissociation enthalpies correspond to the fact that the metallic atom is strongly bonded to the azoles in both configurations. The NBO analysis shows that the systems can be considered as formed by the azolates interacting with the charged metallic atom and thus the Natural Energy Decomposition Analysis (NEDA) indicates that the main attractive force is the electrostatic. Copyright © 2009 John Wiley & Sons, Ltd.     

溶液阴极辉光放电光谱信号的内标法定量分析研究

溶液阴极辉光放电-原子发射光谱是一种新颖的快速、高效、实时在线的元素分析方法,它可用于水体金属元素的检测。为提高其测量精确度和稳定性,将内标法应用于溶液阴极辉光放电-原子发射光谱技术。对K元素建立了标准定标曲线和以H_β为内标元素的定标曲线,内标法测得样品的相对误差和相对标准偏差分别为1.11%,2.14%,精确度和稳定性较之标准曲线法有一定的提高。实验考察了元素谱线强度在同一时段的波动情况,发现元素K和H_β的谱线强度变化趋势稍有不同,而同主族元素K和Rb,Ca和Mg的谱线强度有相同的变化趋势,提出选择与待测元素同主族且谱线强度变化趋势较为一致的元素作为内标元素能更大化校正实验波动的观点。同时探讨了K以Rb为内标元素、Ca以Mg为内标元素以及Mg以Ca为内标元素时的内标法测量的精确度和稳定性,得其相对误差分别为0.49%,0.02%和0.30%,相对标准偏差分别为1.11%,1.13%和0.87%,与标准曲线法和以H_β为内标元素的内标法相比效果更佳。测得自来水样品中Ca元素以Mg为内标的相对误差和相对标准偏差为0.58%,1.03%,Mg元素以Ca为内标的相对误差和相对标准偏差为1.57%和1.10%。研究结果表明,将溶液阴极辉光放电-原子发射光谱技术应用于水体金属元素检测时,内标法可以有效校正实验波动的影响,提高测量的精确度和稳定性。     

Preparation and characterization of blend polymer electrolyte film based on poly(vinyl alcohol)-poly(acrylonitrile)/MgCl<Subscript>2</Subscript> for energy storage devices

The development of magnesium electrolytes for battery applications has been the demand for electrochemical devices. To meet such demand, in this work solid blend polymer electrolytes were prepared using polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) (92.5PVA:7.5PAN) as host polymer, magnesium chloride (MgCl₂) of different molar mass percentage (m.m.%) (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6%) as salt and dimethylformamide (DMF) as solvent. Structural, vibrational, thermal, electrical, and electrochemical properties of the prepared electrolytes were investigated using different techniques such as X-ray diffraction pattern, FTIR spectroscopy analysis, differential scanning calorimetry (DSC), AC impedance measurement, and transference number measurement. X-ray diffraction studies confirm the minimum volume fraction of crystalline phase for the polymer electrolyte with 0.5 m.m.% of MgCl₂. FTIR confirms the complex formation between host polymer and salt. DSC analysis proves the thermal transition of the prepared films are affected by salt concentration. The optimized material with 0.5 m.m.% of MgCl₂ offers a maximum electrical conductivity of 1.01 × 10^?3 S cm^?1 at room temperature. The Mg²⁺ ion conduction in the blend polymer electrolyte is confirmed from transference number measurement. Electrochemical analysis demonstrates the promising characteristic of these polymer films suitable as electrolytes for primary magnesium batteries. Output potential and discharge characteristics have been analyzed for primary magnesium battery which is constructed using optimized conducting electrolyte.     

火焰原子吸收法测定高纯饱和氯化钠溶液中的微量Ca和Mg

建立了先用４０１型螯合树脂分离饱和氯化钠溶液中Ｃａ和Ｍｇ再用火焰原子吸收法测定Ｃａ和Ｍｇ的方法。采用优化法研究了从基体预先分离Ｃａ和Ｍｇ的操作条件,本法的相对标准偏差分别为６．５％和５．５％,回收率分别为９９％和９４％。     

Osteoblastic cell response on magnesium-incorporated apatite coatings

Magnesium is one of the most important bivalent ions associated with biological apatite. A series of magnesium-substituted calcium apatite coatings (Ca_10−xMg_x)(PO₄)₆(OH)₂, where x = 0, 0.50, 1.00, 1.50 and 2.00, are synthesized onto Ti6Al4V substrate by sol-gel dip-coating method to determine how magnesium influences the synthesis and the resulting structural and biological properties. X-ray diffraction (XRD) analysis shows that the incorporation of magnesium helps formation of Mg-containing β-TCP (β-TCMP) phase. X-ray photoelectron spectroscopy (XPS) is used to study the chemical composition and the results show that the apatite structure can only host magnesium less than ∼2.4 wt.% beyond which magnesium aggregates on the surfaces. The incorporation of magnesium slows down the dissolution of Ca²⁺ from the coating. The in vitro behavior of the coatings is evaluated with human osteosarcoma MG63 cells for cell morphology and proliferation. Similar cell morphologies are observed on all coatings. The cell proliferation results show that the incorporation of magnesium up to x = 2 has no adverse effect on cell growth.     

火焰原子吸收光谱法快速测定蜂蜜中的锰和镁

应用火焰原子吸收光谱法测定蜂蜜中锰和镁的含量,分别采用酸消解法和酸浸提法对样品进行预处理。探讨了酸浸提法快速测定蜂蜜中锰和镁的可行性。实验结果表明,两种预处理方法所获得的结果吻合。酸浸提法测定锰和镁的相对标准偏差分别为2.74%—3.47%和1.65%—1.69%;方法的回收率分别为98.0%和97.4%。     

Determination of the content and localization of magnesium in bioapatite of bone

Using x-ray diffraction, electrothermal atomization atomic absorption spectroscopy, and scanning electron microscopy with an x-ray microanalysis, we have studied the phase decomposition of biogenic and synthetic Mg-containing apatite at 900°C with formation of β-tricalcium-magnesium phosphate (β-TCMP). Employing simplified model representations, we obtained a relation that couples the initial Mg concentration with the degree of transformation of apatite into β-TCMP. It is shown that for the β-TCMP contents measured in bioapatite samples and on replacement of calcium by magnesium to about 8% in this phase the calculated range of Mg concentrations coincides with that available in literature sources (0.2–0.6 wt. %). A comparative investigation of the products of decomposition of biogenic and synthetic apatite by the methods of analysis of the composition and structure has established that the formation of β-TCMP is limited by both the insufficient concentration of magnesium and the small sizes of the crystals. The results of the investigations carried out together with the experimental data known from the literature are indicative of the nonuniform distribution of magnesium in the bulk of crystals of biogenic and synthetic apatite, with its predominant localization at the surface sites of the lattice. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 821–826, November–December, 2005.     

Intercalation of magnesium–urea complex into swelling clay

N fertilization is considered as a main source of N₂O and NO emission from agricultural soils. Especially, it is a great challenge to enhance urea efficiency without any deleterious effects on the environment because of massive application of urea. In this study, we attempted to stabilize urea in the interlayer space of montmorillonite (MMT) in order to reduce urea loss from soils. Urea was successfully intercalated in the form of urea–magnesium complexes. The stabilization of urea–magnesium complexes within the interlayer space was confirmed by a significant expansion of the interlayer space and the presence of urea–magnesium complexes. Urea degradation in soils was significantly delayed by application of the urea–magnesium complex intercalated into MMT. It is highly feasible that stabilization of urea within nanosized interlayer space would lead to considerable improvement of nitrogen efficiency in soils.     

几种典型烟火药剂的动摩擦系数测算

 摩擦作用对烟火药剂的生产以及使用过程的安全性至关重要,而动摩擦系数是定量研究烟火药剂摩擦做功能力的关键参数。基于MGY-1型摆式摩擦仪的物理模型,结合数值计算方法,得到了测算动摩擦系数的方法。利用该方法测算了硝酸钾、镁铝合金粉及硫磺3种常用烟火药剂单质以及硝酸钾/镁铝合金粉及硝酸钾/硫磺两种混合物的动摩擦系数。结果表明：5种烟火药剂的动摩擦系数为一个范围值;在硝酸钾中加入镁铝合金粉和硫磺后,混合粉末的动摩擦系数较硝酸钾单质减小。从理论上对产生这两种现象的原因进行了分析。